WorldWideScience

Sample records for duodenal mechanical behaviour

  1. Hormonal mechanisms of cooperative behaviour

    Science.gov (United States)

    Soares, Marta C.; Bshary, Redouan; Fusani, Leonida; Goymann, Wolfgang; Hau, Michaela; Hirschenhauser, Katharina; Oliveira, Rui F.

    2010-01-01

    Research on the diversity, evolution and stability of cooperative behaviour has generated a considerable body of work. As concepts simplify the real world, theoretical solutions are typically also simple. Real behaviour, in contrast, is often much more diverse. Such diversity, which is increasingly acknowledged to help in stabilizing cooperative outcomes, warrants detailed research about the proximate mechanisms underlying decision-making. Our aim here is to focus on the potential role of neuroendocrine mechanisms on the regulation of the expression of cooperative behaviour in vertebrates. We first provide a brief introduction into the neuroendocrine basis of social behaviour. We then evaluate how hormones may influence known cognitive modules that are involved in decision-making processes that may lead to cooperative behaviour. Based on this evaluation, we will discuss specific examples of how hormones may contribute to the variability of cooperative behaviour at three different levels: (i) within an individual; (ii) between individuals and (iii) between species. We hope that these ideas spur increased research on the behavioural endocrinology of cooperation. PMID:20679116

  2. [Oxidative stress in mechanism of psychosomatic disorders realization in duodenal ulcer in students].

    Science.gov (United States)

    Oparin, A G; Oparin, A A

    2005-01-01

    To study the role of oxidative stress in mechanism of psychosomatic disorders involvement in pathogenesis of ulcerogenesis. Psychosomatic disorders (PSD) and oxidative stress (OS) were assessed in 120 students with duodenal ulcer (DU) who had no concomitant pathology. Examination for PSD included interviewing by questionnaires. OS was judged by the level of lipid peroxidation products (malonic dialdehyde and dienic conjugates) and antioxidant activity--by glutathion peroxidase and superoxidedismutase. Melatonin was measured by enzyme immunoassay. A close correlation was discovered between the severity and features of PSD, lowering of melatonin, severity of OS and clinical features of the disease. DU students develop PSD which become leading factors of ulcerogenesis. One of the mechanisms of their participation in ulcerogenesis may be related with lowering of melatonin which is a potent stress regulator and corrector of lipid peroxidation and antioxidant activity.

  3. Mechanical behaviour of structural ceramics

    Directory of Open Access Journals (Sweden)

    Bueno, S.

    2007-06-01

    Full Text Available The use of ceramic materials in structural applications is limited by the lack of reliability associated with brittle fracture behaviour. In order to extend the structural use of ceramics, the design of microstructures which exhibit flaw tolerance due to toughening mechanisms which produce an increase in crack growth resistance during crack propagation has been proposed. This work is a review of the mechanical behaviour of structural ceramic materials and its characterisation. Firstly, the basic brittle fracture parameters and the statistical criteria to determine the probability of exceeding the safety factors demanded for a particular application are analysed. Then, the toughening mechanisms which can be developed in the materials through microstructural design as well as the mechanical characterisation of toughened ceramics are discussed. The experimental values of linear elastic fracture toughness parameters (critical stress intensity factor, KIC, and critical energy release rate, GIC are not intrinsic properties for toughened materials and depend on crack length and the loading system. In this work, the different mechanical parameters proposed to characterise such materials are reviewed. The following fracture parameters are analysed: work of fracture (γWOF, critical J-integral value (JIC and R-curve. For the determination, stable fracture tests are proposed in order to ensure that the energy provided during the test is no more than the necessary one for crack propagation.

    El uso de los materiales cerámicos en aplicaciones estructurales está limitado por la falta de fiabilidad asociada a su comportamiento frágil durante la fractura. Para extender su aplicación se ha propuesto el diseño de microestructuras que presenten tolerancia a los defectos debido a la actuación de mecanismos de refuerzo. Este trabajo es una puesta al día sobre el estudio del comportamiento mecánico de los materiales cerámicos estructurales y su

  4. Ingested Fish Bone: An Unusual Mechanism of Duodenal Perforation and Pancreatic Trauma

    Directory of Open Access Journals (Sweden)

    Dimitrios Symeonidis

    2012-01-01

    Full Text Available Ingestion of gastrointestinal foreign bodies represents a challenging clinical scenario. Increased morbidity is the price for the delayed diagnosis of complications and timely treatment. We present a case of 57-year-old female patient which was admitted in the emergency room department complaining of a mid-epigastric pain over the last twenty-four hours. Based on the patient's history, physical examination and elevated serum amylase levels, a false diagnosis of pancreatitis, was initially adopted. However, a CT scan confirmed the presence of a radiopaque foreign body in the pancreatic head and the presence of air bubbles outside the intestinal lumen. The patient was unaware of the ingestion of the foreign body. At laparotomy, after an oblique duodenotomy, a fish bone pinned in the pancreatic head after the penetration of the medial aspect of the second portion of the duodenal wall was identified and successfully removed. The patient had an uneventful postoperative recovery. Wide variation in clinical presentation characterizes the complicated fish bone ingestions. The strategically located site of penetration in the visceral wall is responsible for the often extraordinary gastrointestinal tract injury patterns. Increased level of suspicion is of paramount importance for the timely diagnosis and treatment.

  5. Duodenal lipoma associated with ectopic duodenal glands

    Directory of Open Access Journals (Sweden)

    Dianbo Cao

    2011-12-01

    Full Text Available Duodenal lipomas are relatively uncommon and are rarely responsible for clinical symptoms. Occasionally, searching for aetiology of gastrointestinal bleeding leads to the final diagnosis of duodenal lipomas. Here, we present the case of a 68-year-old woman who suffered with repeated melena and weight loss. Endoscopy, abdominal computed tomography (CT and histopathological outcomes are described in this case of duodenal lipoma with ectopic duodenal glands.

  6. Mechanical Behaviour of Materials Volume II Fracture Mechanics and Damage

    CERN Document Server

    François, Dominique; Zaoui, André

    2013-01-01

    Designing new structural materials, extending lifetimes and guarding against fracture in service are among the preoccupations of engineers, and to deal with these they need to have command of the mechanics of material behaviour. This ought to reflect in the training of students. In this respect, the first volume of this work deals with elastic, elastoplastic, elastoviscoplastic and viscoelastic behaviours; this second volume continues with fracture mechanics and damage, and with contact mechanics, friction and wear. As in Volume I, the treatment links the active mechanisms on the microscopic scale and the laws of macroscopic behaviour. Chapter I is an introduction to the various damage phenomena. Chapter II gives the essential of fracture mechanics. Chapter III is devoted to brittle fracture, chapter IV to ductile fracture and chapter V to the brittle-ductile transition. Chapter VI is a survey of fatigue damage. Chapter VII is devoted to hydogen embrittlement and to environment assisted cracking, chapter VIII...

  7. Mechanical behaviour of nanoparticles: Elasticity and plastic deformation mechanisms

    Indian Academy of Sciences (India)

    Celine Gerard; Laurent Pizzagalli

    2015-06-01

    Nano-objects often exhibit drastically different properties compared to their bulk counterpart, opening avenues for new applications in many fields, such as in advanced composite materials, nanomanufacturing, nanoelectromechanical systems etc. As such, related research topics have become increasingly prominent in recent years. In this review on the mechanical behaviour of nanoparticles, the main investigation approaches are first briefly presented. The main results in terms of elasticity and plastic deformation mechanisms are then reported and discussed.

  8. The mechanical behaviour of packed particulates

    Energy Technology Data Exchange (ETDEWEB)

    Dutton, R

    1998-01-01

    Within the Canadian Nuclear Fuel Waste Management program, the central concept is to package used fuel in containers that would be deposited in an underground vault in a plutonic rock formation. To provide internal mechanical support for the container, the reference design specifies it to be filled with a matrix of compacted particulate material (called 'packed particulate'), such as quartz sand granules. The focus of this report is on the mechanical properties of the packed-particulate material, based on information drawn from the extant literature. We first consider the packing density of particulate matrices to minimize the remnant porosity and maximize mechanical stability under conditions of external pressure. Practical methods, involving vibratory packing, are reviewed and recommendations made to select techniques to achieve optimum packing density. The behaviour of particulates under compressive loading has been of interest to the powder metallurgy industry (i.e., the manufacture of products from pressed/sintered metal and ceramic powders) since the early decades of this century. We review the evidence showing that in short timescales, stress induced compaction occurs by particle shuffling and rearrangement, elastic distortion, plastic yielding and microfracturing. Analytical expressions are available to describe these processes in a semiquantitative fashion. Time-dependent compaction, mainly via creep mechanisms, is more complex. Much of the theoretical and experimental information is confined to higher temperatures (> 500 degrees C), where deformation rates are more rapid. Thus, for the relatively low ambient temperatures of the waste container ({approx}100 degrees C), we require analytical techniques to extrapolate the collective particulate creep behaviour. This is largely accomplished by employing current theories of creep deformation, particularly in the form of Deformation Mechanism Maps, which allow estimation of creep rates over a wide

  9. Management of duodenal trauma

    Institute of Scientific and Technical Information of China (English)

    CHEN Guo-qing; YANG Hua

    2011-01-01

    Duodenal trauma is uncommon but nowadays seen more and more frequently due to the increased automobile accidents and violent events. The management of duodenal trauma can be complicated, especially when massive injury to the pancreatic-duodenal-biliary complex occurs simultaneously. Even the patients receive surgeries in time, multiple postoperative complications and high mortality are common. To know and manage duodenal trauma better, we searched the recent related literature in PubMed by the keywords of duodenal trauma, therapy, diagnosis and abdomen. It shows that because the diagnosis and management are complicated and the mortality is high,duodenal trauma should be treated in time and tactfully.And application of new technology can help improve the management. In this review, we discussed the incidence,diagnosis, management, and complications as well as mortality of duodenal trauma.

  10. Potentiodynamic behaviour of mechanically polished titanium electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Camara, O.R.; DePauli, C.P.; Giordano, M.C.

    1984-08-01

    The behaviour of titanium electrodes mechanically polished and/or anodically polarized at low positive potential in solutions at constant ionic strength between pH 0.3 and 11.0 is reported. The oxide electroformation potential on a mechanically polished electrode shows a complex dependence on the bulk solution pH. This dependence is similar to that obtained through acid-base titration with titanium as the indicating electrode. The formation of hydroxo-complexes on the spontaneously formed titanium oxide offers a possible explanation for the oxide electroformation potential dependence on pH. Anodic and cathodic wide current peaks are obtained between the potential of the hydrogen evolution and that of the massive oxide electroformation; the corresponding redox system becomes evident at pH 4.0 from the first potentiodynamic cycle. An interpretation of these processes involving the participation of non stoichiometric oxides and hydrogen ions is attempted.

  11. Mechanical behaviour of aluminum screws. Pt. 2. Cyclic behaviour; Tragfaehigkeit von Aluminiumschrauben. T. 2. Zyklische Tragfaehigkeit

    Energy Technology Data Exchange (ETDEWEB)

    Weber, J.O. [Deutscher Schraubenverband, Hagen (Germany); Marx, T. [Adam Opel AG, Ruesselsheim (Germany); Berger, C. [Zentrum fuer Konstruktionswerkstoffe, Institut fuer Werkstoffkunde der Technischen Universitaet Darmstadt (Germany); Arz, U.

    2011-03-15

    This article is the second part of a description of the mechanical behaviour of aluminum screws. The first part describes the mechanical behaviour under static conditions, while the second part details the cyclic behaviour. An overview of the influences to the cyclic behaviour of high strength aluminum screws made of the wrought alloys EN AW 6013, EN AW 6056 and EN AW 7075 is given. In some cases values for EN AW 6082 are presented.

  12. Mechanical Behaviour of the LHC Cryodipoles

    CERN Document Server

    Buenaventura, A; Skoczen, Blazej

    2000-01-01

    The LHC cryodipoles are slender and heavy objects more than 15-m long. The major components of the cryodipole assembly are the 28-tonne cold mass, supported on its three Glass-Fibre-Reinforced-Epoxy support posts and the 4-tonne vacuum vessel. The performance of the LHC depends very much upon the accurate positioning of the dipoles and the beam tubes, in particular to maximise the useful beam apertures. The cryodipoles will be conditioned and measured in surface assembly buildings, then handled and transported to their positions in the tunnel and, finally, aligned. This paper presents the static and dynamic studies of the cryodipole in different configurations. The tests and analyses carried out have led to a thorough understanding of the mechanical behaviour of the cryodipoles. From the static analysis, an hyperstatic supporting system is proposed in order to minimise the systematic deflections and the effects due to changing temperature conditions in the tunnel. The dynamic analysis has shown that the cryod...

  13. Investigations on mechanical behaviour of dental composites.

    Science.gov (United States)

    Ilie, Nicoleta; Hickel, Reinhard

    2009-12-01

    Since a direct comparison of composites efficacy in clinical studies is very difficult, our study aimed to analyse in laboratory tests under standardised and simulated clinical conditions a large variety of commercial composite materials belonging to eight different materials categories. Thus, 72 hybrid, nano-hybrid, micro-filled, packable, ormocer-based and flowable composites, compomers and flowable compomers were compared in terms of their mechanical behaviour. Flexural strength (FS), flexural modulus (FM), diametric tensile (DTS) and compressive strength (CS) were measured after the samples had been stored in water for 24 h at 37 degrees C. Results were statistically analysed using one-way ANOVA with Tukey HSD post hoc test (alpha = 0.05) as well as partial eta2 statistics. Large varieties between the tested materials within the same material category were found. The hybrid, nano-hybrid, packable and ormocer-based composites do not differ significantly among each other as a material type, reaching the highest FS values. Nano-hybrid composites are characterised by a good FS, the best DTS but a low FM. The lowest mechanical properties achieved the micro-filled hybrids. The flowable composites and compomers showed for all properties comparable result. Both flowable material categories do not differ significantly from the micro-filled composites for the most mechanical properties, showing only a higher DTS. The filler volume was shown to have the highest influence on the measured properties, inducing a maximum FS and FM at a level of 60%, whereas such dependence was not measured for DTS or CS. The influence of the type of material on the mechanical properties was significant but very low, showing the strongest influence on the CS.

  14. Mechanical Behaviour of the Wood Masonry

    Directory of Open Access Journals (Sweden)

    Fazia FOUCHAL

    2011-09-01

    Full Text Available In this paper we study the walls wood masonry behaviour. First, we propose a regulatory validation of the walls wood masonry behaviour subjected to vertical and horizontal loads according to Eurocode 5. Then we present the numerical application on the wall wood supported two floors level.

  15. Mechanical Behaviour of Materials Volume 1 Micro- and Macroscopic Constitutive Behaviour

    CERN Document Server

    François, Dominique; Zaoui, André

    2012-01-01

    Advances in technology are demanding ever-increasing mastery over the materials being used: the challenge is to gain a better understanding of their behaviour, and more particularly of the relations between their microstructure and their macroscopic properties.   This work, of which this is the first volume, aims to provide the means by which this challenge may be met. Starting from the mechanics of deformation, it develops the laws governing macroscopic behaviour – expressed as the constitutive equations – always taking account of the physical phenomena which underlie rheological behaviour. The most recent developments are presented, in particular those concerning heterogeneous materials such as metallic alloys, polymers and composites. Each chapter is devoted to one of the major classes of material behaviour.   As the subtitles indicate, Volume 1 deals with micro- and macroscopic constitutive behaviour and Volume 2 with damage and fracture mechanics. A third volume will be devoted to exercises and the...

  16. Duodenal stump leak following a duodenal switch: A case report

    Directory of Open Access Journals (Sweden)

    Lars Nelson

    2015-01-01

    Conclusion: Duodenal stump leaks must be diagnosed as early as possible, and treated appropriately with operative intervention. Regardless of the operative technique the key to appropriate treatment is stabilize the patient, repair the duodenal stump, and adequate drainage.

  17. Mechanical behaviour of aluminium-lithium alloys

    Indian Academy of Sciences (India)

    N Eswara Prasad; A A Gokhale; P Rama Rao

    2003-02-01

    Aluminium-lithium alloys hold promise of providing a breakthrough response to the crying need for lightweight alloys for use as structurals in aerospace applications. Considerable worldwide research has gone into developing a range of these alloys over the last three decades. As a result, substantial understanding has been developed of the microstructure-based micromechanisms of strengthening, of fatigue and fracture as well as of anisotropy in mechanical properties. However, these alloys have not yet greatly displaced the conventionally used denser Al alloys on account of their poorer ductility, fracture toughness and low cycle fatigue resistance. This review aims to summarise the work pertaining to study of structure and mechanical properties with a view to indicate the directions that have been and can be pursued to overcome property limitations.

  18. Micromechanical modelling of mechanical behaviour and strength of wood

    DEFF Research Database (Denmark)

    Mishnaevsky, Leon; Qing, Hai

    2008-01-01

    An overview of the micromechanical theoretical and numerical models of wood is presented. Different methods of analysis of the effects of wood microstructures at different scale levels on the mechanical behaviour, deformation and strength of wood are discussed and compared. Micromechanical models...

  19. Mechanical behaviour of adhesive joint under tensile and shear loading

    NARCIS (Netherlands)

    Jiang, X.; Kolstein, M.H.; Bijlaard, F.S.K.

    2013-01-01

    Due to various advantages of Fibre-Reinforced Polymer (FRP) decks, the FRP to steel composite bridge system is being increasingly used in new bridge structures as well as rehabilitation projects for old bridges. This paper focuses on the mechanical behaviours and failure modes of the adhesively-bond

  20. Believing versus interacting: Behavioural and neural mechanisms underlying interpersonal coordination

    DEFF Research Database (Denmark)

    Konvalinka, Ivana; Bauer, Markus; Kilner, James

    When two people engage in a bidirectional interaction with each other, they use both bottom-up sensorimotor mechanisms such as monitoring and adapting to the behaviour of the other, as well as top-down cognitive processes, modulating their beliefs and allowing them to make decisions. Most researc...

  1. Mechanical behaviour analyses of sap ascent in vascular plants

    Science.gov (United States)

    Perez-Diaz, Jose-Luis; Garcia-Prada, Juan-Carlos; Romera-Juarez, Fernando

    2010-01-01

    A pure mechanical anisotropic model of a tree trunk has been developed based on the 3D finite element method. It simulates the microscopic structure of vessels in the trunk of a European beech (Fagus sylvatica) in order to study and analyse its mechanical behaviour with different configurations of pressures in the conduits of xylem and phloem. The dependence of the strains at the inner bark was studied when sap pressure changed. The comparison with previously published experimental data leads to the conclusion that a great tensile stress—or ‘negative pressure’—must exist in the water column in order to achieve the measured strains if only the mechanical point of view is taken into account. Moreover, the model can help to design experiments where qualitatively knowing the strains and the purely mechanical behaviour of the tree is required. PMID:21886343

  2. Modelling the elastin, collagen and smooth muscle contribution to the duodenal mechanical behaviour in patients with systemic sclerosis

    DEFF Research Database (Denmark)

    Gao, F.; Liao, Donghua; Drewes, Asbjørn Mohr

    2009-01-01

    Abstract Systemic sclerosis (SS) is a connective tissue disease that involves the gastrointestinal tract. Previous experiments have shown abnormal intestinal motility, dilatation, wall stiffening and impaired smooth muscle function. Consequently, understanding the association between intestinal...

  3. Roxatidine in duodenal ulcer.

    OpenAIRE

    1995-01-01

    Roxatidine acetate is a new H2-receptor antagonist. A randomized double-blind clinical trial in fifty-three patients with endoscopically proven duodenal ulcers > 5 mm in diameter was undertaken to compare safety and efficacy of roxatidine with that of ranitidine. Twenty-six patients received roxatidine (75 mg bid) while 27 patients received ranitidine (150 mg bid) for 4 weeks. One patient in each group did not come for follow up. Roxatidine and ranitidine had comparable ulcer healing rates...

  4. Hydrogen influence on the mechanical behaviour of high strength steel

    Energy Technology Data Exchange (ETDEWEB)

    Herenu, Silvina [National Technology Univ. of San Nicolas (Argentina).; National Council of Scientific Research and Technology (Argentina); Armas, Alberto [National Univ. of Rosario (Argentina); Brandaleze, Elena [National Technology Univ. of San Nicolas (Argentina). Metallurgical Dept.; Mansilla, Graciela [National Technology Univ. of San Nicolas (Argentina).

    2010-07-01

    Though numerous studies have been devoted to hydrogen embrittlement in steels, up to date there is not a general agreement about the effect of hydrogen on the mechanical behaviour. The purpose of this paper is to analyze the influence of hydrogen on the mechanical response of high strength steels. Samples were cathodically charged with hydrogen, previous to low cyclic fatigue and tensile tests at room temperature. The presence of hydrogen produces softening effects on the cyclic behaviour and improvements in the fatigue life for low hydrogen contents. The stress-strain curves of tensile tests on pre-charged samples depend on the strain rate imposed. Both tensile and fatigue response could be explained by the hydrogen enhancement of dislocation mobility mechanism. (orig.)

  5. Histological Value of Duodenal Biopsies

    Directory of Open Access Journals (Sweden)

    Limci Gupta

    2005-01-01

    Full Text Available This study was performed to see the value of histopathological diagnosis in management of patients with duodenal biopsies; to look for correlation of histology and serology in suspected cases of coeliac disease; the reasons for taking duodenal biopsies and whether proper adequate histories are provided on the forms sent with request for histopathological view on duodenal biopsies. Here are the observations of the study followed by the discussion.

  6. Duodenal Intracellular Bicarbonate and the 'CF Paradox'

    Directory of Open Access Journals (Sweden)

    Kaunitz JD

    2001-07-01

    Full Text Available HCO(3(- secretion, which is believed to neutralize acid within the mucus gel, is the most studied duodenal defense mechanism. In general, HCO(3(- secretion rate and mucosal injury susceptibility correlate closely. Recent studies suggest that luminal acid can lower intracellular pH (pH(i of duodenal epithelial cells and that HCO(3(- secretion is unchanged during acid stress. Furthermore, peptic ulcers are rare in cystic fibrosis (CF, although, with impaired HCO(3(- secretion, increased ulcer prevalence is predicted, giving rise to the 'CF Paradox'. We thus tested the hypothesis that duodenal epithelial cell protection occurs as the result of pH(i regulation rather than by neutralization of acid by HCO(3(- in the pre-epithelial mucus. Cellular acidification during luminal acid perfusion, and unchanged HCO(3(- secretion during acid stress are inconsistent with pre-epithelial acid neutralization by secreted HCO(3(-. Furthermore, inhibition of HCO(3(- secretion by 5-nitro-2-(3-phenylpropylamino benzoic acid (NPPB despite preservation of pH(i and protection from acid-induced injury further question the pre-epithelial acid neutralization hypothesis. This decoupling of HCO(3(- secretion and injury susceptibility by NPPB (and possibly by CF further suggest that cellular buffering, rather than HCO(3(- exit into the mucus, is of primary importance for duodenal mucosal protection, and may account for the lack of peptic ulceration in CF patients.

  7. Analysis of the mechanical behaviour of the ITER magnet system

    Energy Technology Data Exchange (ETDEWEB)

    Jong, C.T.J.

    1996-03-01

    The International Thermonuclear Experimental Reactor (ITER) is a tokamak fusion device with the objective of demonstrating controlled ignition and an extended burn for a duration sufficient to achieve stationary conditions. The design of ITER will be based on extensive new design work supported by new physical and technological results. As part of the ITER Engineering Design Activities, the mechanical behaviour of the toroidal field coil (TF coil) system during normal operating conditions and fault conditions has to be analyzed. The displacements and/or stresses in the components must be limited to prevent mechanical failure of parts of the overall structure. These Engineering Design Activities are supported by R and D programs in the European Union. This final report describes the work carried out by ECN to develop a finite element model (FE model) of the TF-coil system which is suitable for the analysis of the mechanical behaviour and presents results obtained with this model. For the analysis of the mechanical behaviour, a large three dimensional (3D) non-linear finite element model has been developed. With this FE model a large number of load cases has been analyzed which correspond with several time points during multiple pulses. (orig./WL).

  8. Mechanical and frictional behaviour of nano-porous anodised aluminium

    Energy Technology Data Exchange (ETDEWEB)

    Tsyntsaru, N., E-mail: tintaru@phys.asm.md [Institute of Applied Physics of ASM, 5 Academy str., Chisinau, MD 2028 (Moldova, Republic of); Kavas, B., E-mail: bkavas@ford.com.tr [Istanbul Technical University, Department of Metallurgical and Materials Engineering, 34469 Maslak (Turkey); Ford Otomotiv San A.S., Istanbul (Turkey); Sort, J., E-mail: jordi.sort@uab.cat [Institució Catalana de Recerca i Estudis Avançats (ICREA) and Departament de Física, Universitat Autònoma de Barcelona, E-08193 Bellaterra (Spain); Urgen, M., E-mail: urgen@itu.edu.tr [Istanbul Technical University, Department of Metallurgical and Materials Engineering, 34469 Maslak (Turkey); Celis, J.-P., E-mail: jean-pierre.celis@mtm.kuleuven.be [KU Leuven, Dept. MTM, Kasteelpark Arenberg 44, B-3001 (Belgium)

    2014-12-15

    The porous structure of anodic aluminium oxide (AAO) can be used in versatile applications such as a lubricant reservoir in self-lubricating systems. Such systems are subjected to biaxial loading, which can induce crack formation and propagation, ultimately leading to catastrophic mechanical failure. In this study, the mechanical and tribological behaviour of AAO, prepared from two different types of electrolytes (sulphuric and oxalic acids), are studied in detail. The electrolytic conditions are adjusted to render highly tuneable average pore diameters (between 16 and 75 nm), with porosity levels ranging from 9% to 65%. Well-ordered porous AAO are produced by two-step anodization at rather low temperatures. Mechanical properties, mainly hardness and Young's modulus, are investigated using nanoindentation. Both the porosity degree and the composition of the electrolytic baths used to prepare the AAO have an influence on the mechanical properties. Ball-on-flat configuration was used to estimate the tribological behaviour under dry conditions. No major cracks were observed by scanning electron microscopy, neither after indentation or fretting tests. In the running-in period of tribology experiments the pores were filled with debris. This was followed by the formation of a highly adherent tribolayer – a third body consisting of fine worn particles originated from both the sample and the counterbody. Pore diameter and porosity percentage are found to strongly affect hardness and Young's modulus, but they do not have a major effect on the frictional behaviour. - Highlights: • Well-ordered porous AAO with pore diameters between 16 and 75 nm were produced. • Porosity and composition of electrolytic baths influence the mechanical properties. • Ball-on-flat configuration was used in tribological testing under dry conditions. • Adherent tribolayer consisting of fine worn particles prevents AAO from cracking. • Testing parameters are moreover essential

  9. Modeling the mechanical behaviour of CANDU fuel cladding

    Energy Technology Data Exchange (ETDEWEB)

    Holt, R.A. [Queen' s Univ., Dept. of Mechanical Engineering, Kingston, Ontario (Canada)

    2003-07-01

    Models for the mechanical behaviour of fuel cladding were developed in the period 1973-1983 by staff at AECL CRNL. The models for the mechanical properties of fuel cladding during normal operation were a by-product of programs during the period 1970-1975 to understand the origin of fuel-cladding defects caused by power ramps at Douglas Point and Pickering A. Models for accident conditions were, initially, based heavily on mechanical properties data generated by McGill University and Westinghouse Canada under contract to AECL in the late 1960's and early 1970's and attempts to interpret the data in terms of the underlying deformation mechanisms. The model for normal operating conditions was embodied in the ELESTRES/ELESIM series of codes, and the models for accident conditions were embodied in NIRVANA. (author)

  10. Mechanical behaviour of TWIP steel under shear loading

    Science.gov (United States)

    Vincze, G.; Butuc, M. C.; Barlat, F.

    2016-08-01

    Twinning induced plasticity steels (TWIP) are very good candidate for automotive industry applications because they potentially offer large energy absorption before failure due to their exceptional strain hardening capability and high strength. However, their behaviour is drastically influenced by the loading conditions. In this work, the mechanical behaviour of a TWIP steel sheet sample was investigated at room temperature under monotonic and reverse simple shear loading. It was shown that all the expected features of load reversal such as Bauschinger effect, transient strain hardening with high rate and permanent softening, depend on the prestrain level. This is in agreement with the fact that these effects, which occur during reloading, are related to the rearrangement of the dislocation structure induced during the predeformation. The homogeneous anisotropic hardening (HAH) approach proposed by Barlat et al. (2011) [1] was successfully employed to predict the experimental results.

  11. Economic recession and suicidal behaviour: Possible mechanisms and ameliorating factors.

    Science.gov (United States)

    Haw, Camilla; Hawton, Keith; Gunnell, David; Platt, Stephen

    2015-02-01

    A growing body of research evidence from countries around the world indicates that economic recession is associated with increases in suicide, particularly in males of working age. To explore contributory and ameliorating factors associated with economic recession and suicide and thereby stimulate further research in this area and encourage policy makers to consider how best to reduce the impact of recession on mental health and suicidal behaviour. We conducted a selective review of the worldwide literature focusing on possible risk factors, mechanisms and preventative strategies for suicidal behaviour linked to economic recession. A model of how recession might affect suicide rates is presented. A major and often prolonged effect of recession is on unemployment and job insecurity. Other important effects include those exerted by financial loss, bankruptcy and home repossession. It is proposed these factors may lead directly or indirectly to mental health problems such as depression, anxiety and binge drinking and then to suicidal behaviour. Countries with active labour market programmes and sustained welfare spending during recessions have less marked increases in suicide rates than those that cut spending on welfare and job-search initiatives for the unemployed. Other measures likely to help include targeted interventions for unemployed people, membership of social organisations and responsible media reporting. Good primary care and mental health services are needed to cope with increased demand in times of economic recession but some governments have in fact reduced healthcare spending as an austerity measure. The research evidence linking recession, unemployment and suicide is substantial, but the evidence for the other mechanisms we have investigated is much more tentative. We describe the limitations of the existing body of research as well as make suggestions for future research into the effects of economic recession on suicidal behaviour. © The Author

  12. Study on Mechanical and Physical Behaviour of Hybrid GFRP

    Directory of Open Access Journals (Sweden)

    Nor Bahiyah Baba

    2015-01-01

    Full Text Available The paper discusses the mechanical and physical behaviour of hybrid glass fibre reinforced plastic (GFRP. Hybrid GFRP was fabricated by three different types of glass fibre, namely, 3D, woven, and chopped, which were selected and combined with mixture of polyester resin and hardener. The hybrid GFRP was investigated by varying three parameters which were the composite volume fractions, hybrid GFRP arrangement, and single type fibre. The hybrid GFRP was fabricated by using open mould hand lay-up technique. Mechanical testing was conducted by tensile test for strength and stiffness whereas physical testing was performed using water absorption and hardness. These tests were carried out to determine the effect of mechanical and physical behaviour over the hybrid GFRP. The highest volume fraction of 0.5 gives the highest strength and stiffness of 73 MPa and 821 MPa, respectively. Varying hybrid fibre arrangement which is the arrangement of chopped-woven-3D-woven-chopped showed the best value in strength of 66.2 MPa. The stiffness is best at arrangement of woven-chopped-woven-chopped-woven at 690 MPa. This arrangement also showed the lowest water absorption of 4.5%. Comparing the single fibre type, woven had overtaken the others in terms of both mechanical and physical properties.

  13. Hybrid resection of duodenal tumors.

    Science.gov (United States)

    Poultsides, George A; Pappou, Emmanouil P; Bloom, George Peter; Orlando, Rocco

    2011-09-01

    The aim of this study was to review our experience with the hand-assisted laparoscopic management of duodenal tumors with no or low malignant potential and to compare this approach with published case reports of purely laparoscopic local duodenal resection. Eight cases of hand-assisted laparoscopic local duodenal resection performed from 2000 to 2008 were retrospectively reviewed. Hand-assistance was utilized for complete duodenal mobilization, and local duodenal resection was accomplished extracorporeally through the hand-access incision. Patient and tumor characteristics, operative time, length of stay, and complications were compared with 18 cases of totally laparoscopic local excision of duodenal tumors published since 1997. Patients with ampullary tumors were excluded. Compared with the purely laparoscopic approach, the hand-assisted technique was associated with shorter operative time (179 versus 131 minutes, P=.03) and was more commonly used for lesions located in the third portion of the duodenum (0% versus 37.5%, P=.02). Tumor size (2.9 cm versus 3.2 cm, P=.61) and length of hospital stay (5.9 versus 5.9 days, P=.96) were similar between the two groups. The rate of complications was also comparable (0% versus 12.5%, P=.31); 1 of 8 patients in the hand-assisted group developed an incisional hernia at the hand-access site. Hand-assisted laparoscopic local duodenal resection is a feasible, safe, and effective alternative to the totally laparoscopic approach. In addition to being associated with comparable length of hospital stay, hand-assistance can shorten operative time by facilitating duodenal mobilization as well as extracorporeal duodenal resection and closure.

  14. Roxatidine in duodenal ulcer.

    Directory of Open Access Journals (Sweden)

    Habibullah C

    1995-07-01

    Full Text Available Roxatidine acetate is a new H2-receptor antagonist. A randomized double-blind clinical trial in fifty-three patients with endoscopically proven duodenal ulcers > 5 mm in diameter was undertaken to compare safety and efficacy of roxatidine with that of ranitidine. Twenty-six patients received roxatidine (75 mg bid while 27 patients received ranitidine (150 mg bid for 4 weeks. One patient in each group did not come for follow up. Roxatidine and ranitidine had comparable ulcer healing rates (22/25 vs 22/26; roxatidine, however, resulted in greater reduction in the number and severity of night time pain episodes (p < 0.05. No adverse event was reported during 4 weeks of treatment with roxatidine. Thus roxatidine achieves the primary therapeutic goal of relief of pain better than ranitidine.

  15. Roxatidine in duodenal ulcer.

    Science.gov (United States)

    Habibullah, C M; Habeeb, M A; Singh, S P

    1995-01-01

    Roxatidine acetate is a new H2-receptor antagonist. A randomized double-blind clinical trial in fifty-three patients with endoscopically proven duodenal ulcers > 5 mm in diameter was undertaken to compare safety and efficacy of roxatidine with that of ranitidine. Twenty-six patients received roxatidine (75 mg bid) while 27 patients received ranitidine (150 mg bid) for 4 weeks. One patient in each group did not come for follow up. Roxatidine and ranitidine had comparable ulcer healing rates (22/25 vs 22/26); roxatidine, however, resulted in greater reduction in the number and severity of night time pain episodes (p roxatidine. Thus roxatidine achieves the primary therapeutic goal of relief of pain better than ranitidine.

  16. Paraganglioma gangliocítico duodenal Duodenal gangliocytic paraganglioma

    Directory of Open Access Journals (Sweden)

    C. Prieto

    2005-04-01

    Full Text Available Se presenta el caso de un varón de 85 años que ingresó por dolor abdominal e ictericia, por lo cual se le realizaron diversas exploraciones, apreciandose en 2ª porción duodenal una masa cuyo estudio histológico demostró que se trataba de un paraganglioma gangliocítico duodenal. Se describen las características clínicas de este infrecuente tumor y revisamos su diagnóstico y tratamiento.We present the case of an 85 year old male who was admitted to hospital with abdominal pain and jaundice. Different explorations were performed for this reason, with a mass observed in his 2nd duodenal portion. Histiological study showed that it was a duodenal gangliocytic paraganlioma. The clinical characteristics of this infrequent tumour are described and we review the diagnosis and treatment.

  17. Erosion wear behaviour and mechanism of abradable seal coating

    Institute of Scientific and Technical Information of China (English)

    冉丽萍

    2002-01-01

    The erosion wear behaviour and mechanism of several middle temperature seal coatings were investigated by a CMS-100 self-made vacuum sand erosion machine. The results show that the relationship between the erosion mass loss and the erosion time is linear, the coatings hold a maximum erosion rate at 60° impact angle, and the relationship between the erosion rate and the impact speed is an exponential function. The speed exponent increases with the increase of the impact angle. At 90° impact, indentations and extruded lips were generated on the coating surface subjected to impact. With repetitive impact by the abrasive particles, the extruded lips were work-hardened and peeled off, while flattened metal phase grains were impacted repeatedly, loosed and debonded. At 30° impact, the erosion wear of the coating is characterized by micro-cutting, plowing and tunneling via pores and non-metal phase. The model of the erosion mechanism is advanced on the basis of the above-mentioned erosion wear behaviour.

  18. Thermo-mechanical behaviour of a compacted swelling clay

    CERN Document Server

    Tang, Anh-Minh; Barnel, Nathalie

    2008-01-01

    Compacted unsaturated swelling clay is often considered as a possible buffer material for deep nuclear waste disposal. An isotropic cell permitting simultaneous control of suction, temperature and pressure was used to study the thermo-mechanical behaviour of this clay. Tests were performed at total suctions ranging from 9 to 110 MPa, temperature from 25 to 80 degrees C, isotropic pressure from 0.1 to 60 MPa. It was observed that heating at constant suction and pressure induces either swelling or contraction. The results from compression tests at constant suction and temperature evidenced that at lower suction, the yield pressure was lower, the elastic compressibility parameter and the plastic compressibility parameter were higher. On the other hand, at a similar suction, the yield pressure was slightly influenced by the temperature; and the compressibility parameters were insensitive to temperature changes. The thermal hardening phenomenon was equally evidenced by following a thermo-mechanical path of loading...

  19. Pretreated waste landfilling: relation between leachate characteristics and mechanical behaviour.

    Science.gov (United States)

    Boni, Maria Rosaria; Chiavola, Agostina; Sbaffoni, Silvia

    2006-01-01

    The present paper presents a part of a wider research effort aiming at studying the long-term behaviour of different pre-treated wastes once landfilled; in particular, this paper deals with the analysis of settlements and their correlation with the main leachate biochemical parameters (BOD, COD and pH). The municipal solid waste organic fraction (MSWOF) and bottom ash (BA) from incineration of municipal solid waste (MSW) were considered in the study and used to set up different semi-pilot landfill plants. Particularly, the FT plant contained 90 days aerobically biostabilized MSWOF, the FP plant was filled with 15 days aerobically biostabilized MSWOF and the MX plant with a 30-70% (by weight) mixture of BA and the same MSWOF used in the FP plant. The data obtained showed a faster mechanical and biological stabilization of the FT and MX plants, due to the less biodegradable organic fraction content initially present in the FT plant and to the presence of BA, having a stabilizing effect, in the MX plant. Besides, similar behaviour of FT and MX was observed, and also a strong correlation between the settlement and the biochemical parameters time profiles was identified.

  20. Investigation of the hydro-mechanical behaviour of fouled ballast

    Institute of Scientific and Technical Information of China (English)

    Yu-jun CUI; Trong Vinh DUONG; Anh Minh TANG; Jean-Claude DUPLA; Nicolas CALON; Alain ROBINET

    2013-01-01

    In this study,a fouled ballast taken from the site of Sénissiat,France,was investigated.For the hydraulic behaviour,a large-scale cell was developed allowing drainage and evaporation tests to be carried out with monitoring of both suction and volumetric water content at various positions of the sample.It was observed that the hydraulic conductivity of fouled ballast is decreasing with suction increase,as for common unsaturated soils.The effect of fines content was found to be negligible.For the mechanical behaviour,both monotonic and cyclic triaxial tests were carried out using a large-scale triaxial cell.Various water contents were considered.The results were interpreted in terms of shear strength and permanent axial strain.It appeared that the water content is an important factor to be accounted for since any increase of water content or degree of saturation significantly decreases the shear strength and increases the permanent strain.Constitutive modelling has been attempted based on the experimental results.The model in its current state is capable of describing the effects of stress level,cycle number and water content.

  1. Creep behaviour and creep mechanisms of normal and healing ligaments

    Science.gov (United States)

    Thornton, Gail Marilyn

    Patients with knee ligament injuries often undergo ligament reconstructions to restore joint stability and, potentially, abate osteoarthritis. Careful literature review suggests that in 10% to 40% of these patients the graft tissue "stretches out". Some graft elongation is likely due to creep (increased elongation of tissue under repeated or sustained load). Quantifying creep behaviour and identifying creep mechanisms in both normal and healing ligaments is important for finding clinically relevant means to prevent creep. Ligament creep was accurately predicted using a novel yet simple structural model that incorporated both collagen fibre recruitment and fibre creep. Using the inverse stress relaxation function to model fibre creep in conjunction with fibre recruitment produced a superior prediction of ligament creep than that obtained from the inverse stress relaxation function alone. This implied mechanistic role of fibre recruitment during creep was supported using a new approach to quantify crimp patterns at stresses in the toe region (increasing stiffness) and linear region (constant stiffness) of the stress-strain curve. Ligament creep was relatively insensitive to increases in stress in the toe region; however, creep strain increased significantly when tested at the linear region stress. Concomitantly, fibre recruitment was evident at the toe region stresses; however, recruitment was limited at the linear region stress. Elevating the water content of normal ligament using phosphate buffered saline increased the creep response. Therefore, both water content and fibre recruitment are important mechanistic factors involved in creep of normal ligaments. Ligament scars had inferior creep behaviour compared to normal ligaments even after 14 weeks. In addition to inferior collagen properties affecting fibre recruitment and increased water content, increased glycosaminoglycan content and flaws in scar tissue were implicated as potential mechanisms of scar creep

  2. Current perspectives on behavioural and cellular mechanisms of illness anorexia.

    Science.gov (United States)

    Asarian, Lori; Langhans, Wolfgang

    2005-12-01

    Here we review our current understanding of the integration of immune, neural, metabolic and endocrine signals involved in the generation of anorexia during acute infection, with the focus on anorexia elicited by peripheral administration of bacterial lipopolysaccharide (LPS). We chose to limit this review to peripheral LPS-anorexia because the mechanisms underlying this response may also be valid for anorexia during other types of acute or chronic infections, with slight differences in the duration of anorexia, levels of circulating concentrations of pro-inflammatory cytokines and hypermetabolism. Evidence so far indicates that LPS-anorexia is a complex response beneficial to host defence that involves both peripheral and central action of pro-inflammatory cytokines, other immune factors, such as prostanoids, and neurotransmitters, such as serotonin. One interesting characteristic of LPS-anorexia is its sexual differentiation, an aspect mainly mediated by the gonadal hormone estradiol. Understanding the behavioural and molecular mechanisms of LPS-anorexia may even provide useful leads for identifying mechanisms of eating disorders in humans.

  3. Chromosomal and methylation alterations in sporadic and familial adenomatous polyposis-related duodenal carcinomas.

    NARCIS (Netherlands)

    Berkhout, M.; Nagtegaal, I.D.; Cornelissen, S.J.B.; Dekkers, M.M.G.; Molengraft, F.J. van de; Peters, W.H.M.; Nagengast, F.M.; Krieken, J.H.J.M. van; Jeuken, J.W.M.

    2007-01-01

    Primary carcinomas of the small intestine are rare and the mechanism of their pathogenesis is poorly understood. Patients with familial adenomatous polyposis (FAP) have a high risk of developing duodenal carcinomas. The aim of this study is to gain more insight into the development of duodenal carci

  4. Hydro-mechanical behaviour of bentonite pellet mixtures

    Science.gov (United States)

    Hoffmann, C.; Alonso, E. E.; Romero, E.

    Granular mixtures made of high-density pellets of bentonite are being evaluated as an alternative buffer material for waste isolation. Ease of handling is an often-mentioned advantage. The paper described the experimental program performed to characterize the hydro-mechanical behaviour of compacted pellet’s mixtures used in the engineered barrier (EB) experiment. The material tested in the laboratory was based in the pellet’s mixtures actually used for the emplacement of the EB in situ experiment. Grain size distribution was adjusted to a maximum pellet size compatible with the specimen’s dimensions. Dry densities of statically compacted specimens varied in most of the cases in the range: 1.3-1.5 Mg/m 3. Pellets had a very high dry density, close to 2 Mg/m 3. The outstanding characteristic of these mixtures is its discontinuous porosity. Pore sizes of the compacted pellets vary around 10 nm. However the inter-pellet size of the pores is four to five orders of magnitude higher. This double porosity and the highly expansive nature of the pellets controlled all the hydraulic and mechanical properties of the mixture. Tests performed include infiltration tests using different water injection rates and mechanisms of water transfer (in liquid and vapour phases), suction controlled oedometer tests and swelling pressure tests. The interpretation of some of the tests performed required backanalysis procedures using a hydro-mechanical (HM) computer code. Material response was studied within the framework of the elastoplastic constitutive model proposed by Alonso et al. [Alonso, E.E., Gens, A., Josa, A., 1990. A constitutive model for partially saturated soils. Géotechnique 40 (3), 405-430] (Barcelona Basic Model, BBM). Parameters for the model were identified and also a set of hydraulic laws necessary to perform coupled HM analysis.

  5. MECHANICAL BEHAVIOUR OF ALUMINA-ZIRCONIA COMPOSITE BY SLURRY METHOD

    Directory of Open Access Journals (Sweden)

    JYOTI PRAKASH

    2011-02-01

    Full Text Available Alumina has got some excellent properties like chemical inertness, thermal and mechanical strength against hazardous environment. Alumina is a good ceramic material which is being used for structuralapplications. To enhance the toughness and strength of the body some Zirconia is also used with it. The use of Zirconia in alumina is known as toughening of alumina. One difficulty arises, when alumina and alumina toughened composite are sintered , because the low sinterability of Alumina-Zirconia forced the compact to give very low density body. To overcome this problem alumina and alumina composites are made from slurry method which gives nearly theoretical density. The combined effect of alumina and Zirconia on the phase transformation and microstructure development of heat-treated Alumina-Zirconia composites has been studied. Slurry is prepared by adding water, dispersant, binder and anti-foaming agent. In the present study, Sintering schedule is optimized and kept constant for all samples. After sintering, mechanical behaviour of the composite has been studied.

  6. Post Irradiation Mechanical Behaviour of Three EUROFER Joints

    Energy Technology Data Exchange (ETDEWEB)

    Lucon, E.; Leenaers, A.; Vandermeulen, W.

    2006-08-15

    The post-irradiation mechanical properties of three EUROFER joints (two diffusion joints and one TIG weld) have been characterized after irradiation to 1.8 dpa at 300 degrees Celsius in the BR-2 reactor. Tensile, KLST impact and fracture toughness tests have been performed. Based on the results obtained and on the comparison with data from EUROFER base material irradiated under similar conditions, the post-irradiation mechanical behaviour of both diffusion joints (laboratory and mock-up) appears similar to that of the base material. The properties of the TIG joint are affected by the lack of a post-weld heat treatment, which causes the material from the upper part of the weld to be significantly worse than that of the lower region. Thus, specimens from the upper layer exhibit extremely pronounced hardening and embrittlement caused by irradiation. The samples extracted from the lower layer show much better resistance to neutron exposure, although their measured properties do not match those of the diffusion joints. The results presented demonstrate that diffusion joining can be a very promising technique.

  7. CT of gastro-duodenal obstruction.

    Science.gov (United States)

    Millet, I; Doyon, F Curros; Pages, E; Faget, C; Zins, M; Taourel, P

    2015-10-01

    Gastro-duodenal obstruction encompasses a spectrum of benign and malignant disease. Historically, chronic peptic ulcer disease was the main cause of gastro-duodenal obstruction, whereas now malignant cause with gastric carcinomas for gastric obstruction and pancreatic tumors for duodenal obstruction predominate. This paper reviews the role of CT in diagnosing gastro-duodenal obstruction, its level, its cause by identifying intraluminal, parietal, or extrinsic process, and the presence of complication.

  8. Duodenal duplication cyst identified with MRCP

    Energy Technology Data Exchange (ETDEWEB)

    Carbognin, G.; Guarise, A.; Biasiutti, C.; Pagnotta, N.; Procacci, C. [Department of Radiology, University Hospital ' G.B. Rossi' , Verona (Italy)

    2000-08-01

    We report a case of a stalked cystic duodenal duplication. The lesion, hyperintense on T2-weighted GRE images, maintained the signal intensity after oral administration of a negative contrast agent (Lumirem, Guerbet, Aulnay-Sous-Bois, France), confirming its independence from the duodenal lumen. To our knowledge, this is the first demonstration of duodenal duplication by means of MR cholangiopancreatography. (orig.)

  9. Omeprazole promotes proximal duodenal mucosal bicarbonate secretion in humans.

    Science.gov (United States)

    Mertz-Nielsen, A; Hillingsø, J; Bukhave, K; Rask-Madsen, J

    1996-01-01

    The proton pump inhibitor, omeprazole, surprisingly resulted in higher rates of proximal duodenal mucosal bicarbonate secretion than previously reported using an H2 receptor antagonist for gastric acid inhibition. Gastroduodenal perfusions were performed in healthy volunteers to evaluate whether this incidental finding is explained by more potent gastric acid inhibition by omeprazole or might be caused by the different mode of drug action. Basal and stimulated gastric and duodenal bicarbonate secretion rates were measured in the same subjects in control experiments (n = 17) and after pretreatment with high dose omeprazole (n = 17) and ranitidine (n = 9), respectively, by use of a technique permitting simultaneous measurements. Concentrations of bicarbonate were measured in the respective effluents by the method of back titration. Both omeprazole and ranitidine completely inhibited gastric acid secretion (pH 6.9 v 6.8; p > 0.05). Omeprazole caused higher rates of basal (mean (SEM)) (597 (48) v 351 (39) mumol/h; p 0.05) duodenal bicarbonate secretion compared with control experiments. Also the combination of omeprazole and ranitidine increased (p = 0.05) duodenal bicarbonate secretion, while ranitidine alone caused no change in either basal or stimulated secretion. In the stomach basal as well as vagally stimulated bicarbonate secretion was independent of the means of acid inhibition. These results show that the proton pump inhibitor, omeprazole, promotes proximal duodenal mucosal bicarbonate secretion apparently independent of its gastric acid inhibitory effect. The mechanism of action remains speculative.

  10. Numerical modelling of the time-dependent mechanical behaviour of softwood

    DEFF Research Database (Denmark)

    Engelund, Emil Tang

    2010-01-01

    When using wood as a structural material it is important to consider its time-dependent mechanical behaviour and to predict this behaviour for decades ahead. For this purpose, several rheological mathematical models, spanning from fairly simple to very complex ones, have been developed over...... the microfibrils. This assumption is incorporated in the numerical model by only allowing non-elastic behaviour in shear deformation modes in the local coordinate system. The rate of shearing is described by deformation kinetics. The results indicate that time-dependent behaviour such as creep and relaxation...... mechanisms causing the observed mechanical behaviour. In this study, the mechanical behaviour of softwood tracheids is described using numerical modelling. The basic composition and orientation of the tracheid constituents is incorporated by establishing a local coordinate system aligned...

  11. Numerical modelling of the time-dependent mechanical behaviour of softwood

    DEFF Research Database (Denmark)

    Engelund, Emil Tang

    2010-01-01

    When using wood as a structural material it is important to consider its time-dependent mechanical behaviour and to predict this behaviour for decades ahead. For this purpose, several rheological mathematical models, spanning from fairly simple to very complex ones, have been developed over...... mechanisms causing the observed mechanical behaviour. In this study, the mechanical behaviour of softwood tracheids is described using numerical modelling. The basic composition and orientation of the tracheid constituents is incorporated by establishing a local coordinate system aligned...... the microfibrils. This assumption is incorporated in the numerical model by only allowing non-elastic behaviour in shear deformation modes in the local coordinate system. The rate of shearing is described by deformation kinetics. The results indicate that time-dependent behaviour such as creep and relaxation...

  12. Multiple giant duodenal ulcers associated with duodenal gastrinoma.

    Science.gov (United States)

    Fujihara, Shintaro; Mori, Hirohito; Nishiyama, Noriko; Kobayashi, Mitsuyoshi; Kobara, Hideki; Masaki, Tsutomu

    2012-02-01

    A 59-year-old Japanese man with a history of chronic hepatitis C and cirrhosis was admitted to hospital because of severe abdominal pain and diarrhea. His discomfort had begun 2 months earlier and was localized to the upper abdomen. Upper gastrointestinal endoscopy showed multiple ulcerative lesions from the duodenal bulb to the descending part of the duodenum, one of which was a giant ulcer that filled half of the intestinal lumen. Despite continuous intravenous lansoprazole therapy, his abdominal symptoms did not improve. Upper gastrointestinal endoscopy was again performed to detect the tumor, but it was difficult to observe the tumor with a conventional endoscope. We then inverted a transnasal endoscope into the duodenum, and this enabled us to detect a 15-mm submucosal tumor in the upper wall of the duodenal bulb. Examination of specimens from endoscopic ultrasonography fine-needle aspiration biopsy of the tumor revealed gastrinoma in the duodenal bulb. We decided to perform an operative resection. The patient's symptoms resolved after surgery, and he remained asymptomatic at follow-up 18 months later. Therefore, when it is difficult to detect the tumor directly by conventional endoscopy, we recommend that attempts be made to detect the tumor by inverting a transnasal endoscope into the duodenal bulb.

  13. Mechanisms and behavioural functions of structural coloration in cephalopods.

    Science.gov (United States)

    Mäthger, Lydia M; Denton, Eric J; Marshall, N Justin; Hanlon, Roger T

    2009-04-06

    Octopus, squid and cuttlefish are renowned for rapid adaptive coloration that is used for a wide range of communication and camouflage. Structural coloration plays a key role in augmenting the skin patterning that is produced largely by neurally controlled pigmented chromatophore organs. While most iridescence and white scattering is produced by passive reflectance or diffusion, some iridophores in squid are actively controlled via a unique cholinergic, non-synaptic neural system. We review the recent anatomical and experimental evidence regarding the mechanisms of reflection and diffusion of light by the different cell types (iridophores and leucophores) of various cephalopod species. The structures that are responsible for the optical effects of some iridophores and leucophores have recently been shown to be proteins. Optical interactions with the overlying pigmented chromatophores are complex, and the recent measurements are presented and synthesized. Polarized light reflected from iridophores can be passed through the chromatophores, thus enabling the use of a discrete communication channel, because cephalopods are especially sensitive to polarized light. We illustrate how structural coloration contributes to the overall appearance of the cephalopods during intra- and interspecific behavioural interactions including camouflage.

  14. Chaotic behaviour of Zeeman machines at introductory course of mechanics

    Science.gov (United States)

    Nagy, Péter; Tasnádi, Péter

    2016-05-01

    Investigation of chaotic motions and cooperative systems offers a magnificent opportunity to involve modern physics into the basic course of mechanics taught to engineering students. In the present paper it will be demonstrated that Zeeman Machine can be a versatile and motivating tool for students to get introductory knowledge about chaotic motion via interactive simulations. It works in a relatively simple way and its properties can be understood very easily. Since the machine can be built easily and the simulation of its movement is also simple the experimental investigation and the theoretical description can be connected intuitively. Although Zeeman Machine is known mainly for its quasi-static and catastrophic behaviour, its dynamic properties are also of interest with its typical chaotic features. By means of a periodically driven Zeeman Machine a wide range of chaotic properties of the simple systems can be demonstrated such as bifurcation diagrams, chaotic attractors, transient chaos and so on. The main goal of this paper is the presentation of an interactive learning material for teaching the basic features of the chaotic systems through the investigation of the Zeeman Machine.

  15. Behavioural and physiological mechanisms of polarized light sensitivity in birds

    Science.gov (United States)

    Muheim, Rachel

    2011-01-01

    Polarized light (PL) sensitivity is relatively well studied in a large number of invertebrates and some fish species, but in most other vertebrate classes, including birds, the behavioural and physiological mechanism of PL sensitivity remains one of the big mysteries in sensory biology. Many organisms use the skylight polarization pattern as part of a sun compass for orientation, navigation and in spatial orientation tasks. In birds, the available evidence for an involvement of the skylight polarization pattern in sun-compass orientation is very weak. Instead, cue-conflict and cue-calibration experiments have shown that the skylight polarization pattern near the horizon at sunrise and sunset provides birds with a seasonally and latitudinally independent compass calibration reference. Despite convincing evidence that birds use PL cues for orientation, direct experimental evidence for PL sensitivity is still lacking. Avian double cones have been proposed as putative PL receptors, but detailed anatomical and physiological evidence will be needed to conclusively describe the avian PL receptor. Intriguing parallels between the functional and physiological properties of PL reception and light-dependent magnetoreception could point to a common receptor system. PMID:21282180

  16. Behavioural and physiological mechanisms of polarized light sensitivity in birds.

    Science.gov (United States)

    Muheim, Rachel

    2011-03-12

    Polarized light (PL) sensitivity is relatively well studied in a large number of invertebrates and some fish species, but in most other vertebrate classes, including birds, the behavioural and physiological mechanism of PL sensitivity remains one of the big mysteries in sensory biology. Many organisms use the skylight polarization pattern as part of a sun compass for orientation, navigation and in spatial orientation tasks. In birds, the available evidence for an involvement of the skylight polarization pattern in sun-compass orientation is very weak. Instead, cue-conflict and cue-calibration experiments have shown that the skylight polarization pattern near the horizon at sunrise and sunset provides birds with a seasonally and latitudinally independent compass calibration reference. Despite convincing evidence that birds use PL cues for orientation, direct experimental evidence for PL sensitivity is still lacking. Avian double cones have been proposed as putative PL receptors, but detailed anatomical and physiological evidence will be needed to conclusively describe the avian PL receptor. Intriguing parallels between the functional and physiological properties of PL reception and light-dependent magnetoreception could point to a common receptor system.

  17. Coping styles and behavioural flexibility : towards underlying mechanisms

    NARCIS (Netherlands)

    Coppens, Caroline M; de Boer, Sietse F; Koolhaas, Jaap M

    2010-01-01

    A coping style (also termed behavioural syndrome or personality) is defined as a correlated set of individual behavioural and physiological characteristics that is consistent over time and across situations. This relatively stable trait is a fundamental and adaptively significant phenomenon in the b

  18. [Various mechanisms of cytoprotective effect of omeprazole and low intensity laser radiation on the gastroduodenal mucosa in the treatment of patients with duodenal ulcer].

    Science.gov (United States)

    Akhmadkhodzhaev, A M

    2002-01-01

    Clinical studies were made in 130 patients with duodenal ulcer in the phase of exacerbation of the disease. There were 98 men and 32 women who ranged from 17 to 50 years old. Results of examination of 7 essentially healthy subjects were regarded as control. The patients were divided into three groups. Group I patients (n = 48) received a conventional therapy; in group II patients, the adopted therapy was supplemented by omeprazol, 20 mg twice daily, group III patients (n = 43) were (in addition to the above therapeutic regimen) exposed to a session of endoscopic low-intensity laser irradiation (LILI) for 5 min (overall 6 to 8 LILI procedures). It has been ascertained that omeprazol exerts a cytoprotective effect on the mucozal barrier of the gastroduodenal zone brought about by increase in the synthesis of glucoproteins in the mucous membrane, improvement of the water-and-elastic properties, and enhancement of resistance of the mucosal barrier to the action of the aggressive factors. Administration of endoscopic LILI treatments in DU patients has also been found out to have a cytoprotective effect but superior to omeprazol. A protective action of LILI is believed to be caused by stimulation of synthesis of the most important components of glycoproteins. A cytoprotective effect of omeprazol and endoscopic LILI is ccompanied by a significant shortening of time for the clinical symptoms to get dispelled, the ulcer cicatrization frequency increased.

  19. Down-regulation of pancreatic and duodenal homeobox-1 by somatostatin receptor subtype 5: a novel mechanism for inhibition of cellular proliferation and insulin secretion by somatostatin

    Directory of Open Access Journals (Sweden)

    Charles eBrunicardi

    2014-06-01

    Full Text Available Somatostatin is a regulatory peptide and acts as an endogenous inhibitory regulator of the secretory and proliferative responses of target cells. Somatostatin’s actions are mediated by a family of seven transmembrane domain G protein-coupled receptors that comprise five distinct subtypes (SSTR1-5. SSTR5 is one of the major SSTRs in the islets of Langerhans. Homeodomain-containing transcription factor pancreatic and duodenal homeobox-1 (PDX-1 is essential for pancreatic development, β cell differentiation, maintenance of normal β cell functions in adults and tumorigenesis. Recent studies show that SSTR5 acts as a negative regulator for PDX-1 expression and that SSTR5 mediates somatostatin’s inhibitory effect on cell proliferation and insulin expression/excretion through down-regulating PDX-1 expression. SSTR5 exerts its inhibitory effect on PDX-1 expression at both the transcriptional level by down-regulating PDX-1 mRNA and the post-translational level by enhancing PDX-1 ubiquitination. Identification of PDX-1 as a transcriptional target for SSTR5 may help in guiding the choice of therapeutic cancer treatments.

  20. Modelling time-dependent mechanical behaviour of softwood using deformation kinetics

    DEFF Research Database (Denmark)

    Engelund, Emil Tang; Svensson, Staffan

    2010-01-01

    The time-dependent mechanical behaviour (TDMB) of softwood is relevant, e.g., when wood is used as building material where the mechanical properties must be predicted for decades ahead. The established mathematical models should be able to predict the time-dependent behaviour. However, these models...

  1. CLINICAL STUDY OF DUODENAL PERFORATION

    Directory of Open Access Journals (Sweden)

    Sambasiva Rao

    2016-04-01

    Full Text Available BACKGROUND The duodenal injury can pose a formidable challenge to the surgeon and failure to manage it properly may have devastating results. Over the centuries, there was little to offer the patient of acute abdomen beyond cupping, purgation and enemas, all of which did more harm than good. It was not until 1884 that Mikulicz made an attempt to repair a perforation. Recent statistics indicate roughly 10% of population develop gastric or duodenal ulcer in life time. Roughly 1-3% of population above the age of 20 years have some degree of peptic ulcer activity during any annual period. A detailed history with regards to the signs and symptoms of the patient, a meticulous examination, radiological and biochemical investigations help to arrive at a correct preoperative diagnosis. In this study, a sincere effort has been put to understand the demographic patterns, to understand the underlying aetiology and to understand the effectiveness of the standard methods of investigation and treatment in use today. METHODS This is a 24 months prospective study i.e., from September 2011 to September 2013 carried out at Dr. Pinnamaneni Siddhartha Institute of Medical Sciences & Research Foundation. The study included the patients presenting to Dr. Pinnamaneni Siddhartha Institute of Medical Sciences & Research Foundation to emergency ward with signs and symptoms of hollow viscus perforation. The sample size included 30 cases of duodenal perforation. RESULTS Duodenal ulcer perforation commonly occurs in the age group of 30-60 years, but it can occur in any age group. Majority of the patients were male. Smoking and alcohol consumption were risk factors in most cases (53.3% for the causation of duodenal ulcer perforation. Sudden onset of abdominal pain, situated at epigastrium and right hypochondrium was a constant symptom (100%. Vomiting, constipation and fever were not so common. CONCLUSION The emergency surgical management for perforated duodenal ulcer is by

  2. Numerical and experimental investigation of bump foil mechanical behaviour

    DEFF Research Database (Denmark)

    Larsen, Jon Steffen; Cerda Varela, Alejandro Javier; Santos, Ilmar

    2014-01-01

    Corrugated foils are utilized in air foil bearings to introduce compliance and damping thus accurate mathematical predictions are important. A corrugated foil behaviour is investigated experimentally as well as theoretically. The experimental investigation is performed by compressing the foil, be...

  3. Mechanical Behaviour of Bolted Joints Under Impact Rates of Loading

    Science.gov (United States)

    2012-01-01

    P., Pascoe , K., Polak, C., & Stroud, D. (1986). The Behaviour of Single-Lap Bolted Joints in CFRP Laminates. Composite Structures, 41-55...Interferometry. J Nondestruct Eval, 135-142. Smith, P., Pascoe , K., Polak, C., & Stroud, D. (1986). The Behaviour of Single-Lap Bolted Joints in...in [Kretsis & Matthews, 1985], [Smith, Pascoe , Polak, & Stroud, 1986],[Godwin & Matthews, 1980] UNCLASSIFIED UNCLASSIFIED implies that under

  4. Mechanical behaviour׳s evolution of a PLA-b-PEG-b-PLA triblock copolymer during hydrolytic degradation.

    Science.gov (United States)

    Breche, Q; Chagnon, G; Machado, G; Girard, E; Nottelet, B; Garric, X; Favier, D

    2016-07-01

    PLA-b-PEG-b-PLA is a biodegradable triblock copolymer that presents both the mechanical properties of PLA and the hydrophilicity of PEG. In this paper, physical and mechanical properties of PLA-b-PEG-b-PLA are studied during in vitro degradation. The degradation process leads to a mass loss, a decrease of number average molecular weight and an increase of dispersity index. Mechanical experiments are made in a specific experimental set-up designed to create an environment close to in vivo conditions. The viscoelastic behaviour of the material is studied during the degradation. Finally, the mechanical behaviour is modelled with a linear viscoelastic model. A degradation variable is defined and included in the model to describe the hydrolytic degradation. This variable is linked to physical parameters of the macromolecular polymer network. The model allows us to describe weak deformations but become less accurate for larger deformations. The abilities and limits of the model are discussed.

  5. Abdominal compartment syndrome from bleeding duodenal diverticulum

    Directory of Open Access Journals (Sweden)

    Vakhtang Tchantchaleishvili

    2012-01-01

    Full Text Available Duodenal diverticuli are acquired false diverticuli of unknown etiology. Although mostly asymptomatic, they can occasionally cause upper gastrointestinal hemorrhage, rarely with massive bleeding. In this report, we present (to the best of our knowledge the first reported case of duodenal diverticular bleeding, causing abdominal compartment syndrome. Albeit a rare event, duodenal diverticular bleeding should be included in the differential diagnosis of upper gastrointestinal bleeding. As with our case, a multidisciplinary approach to managing such patients is crucial.

  6. Mechanical Properties and Fracture Behaviour of Multilayer Alumina Composites

    Institute of Scientific and Technical Information of China (English)

    ZHENG Xinguo; ZHAO Fei; ZHANG Jinyong

    2015-01-01

    Adopting a ceramic/polymer multilayer structure design to simulate the structure of nacre is usually believed to be an effective way to increase the toughness of ceramic composites at the expense of the material's bending strength. However, in this study, we found that both the bending strength and the toughness could be improved simultaneously when using a certain Al2O3/Kevlar multilayer composite design compared to pure alumina samples with the same dimensions. The fracture behaviour of the Al2O3/Kevlar multilayer composite was studied to ifnd a reason for this improvement. The results showed that the complex and asymmetrical stresses occurring in the Kevlar-reinforced layers were the main reason for the differences in fracture behaviour. We expect our results to open up new ways for the design of future high performance ceramic composites.

  7. Aero dynamical and mechanical behaviour of the Savonius rotor

    Energy Technology Data Exchange (ETDEWEB)

    Aouachria, Z. [Batna Univ., (Algeria). Applied Energetic Physics Laboratory

    2009-07-01

    Although the Savonius wind turbine is not as efficient as the traditional Darrieus wind turbine, its rotor design has many advantages such as simple construction; acceptance of wind from all directions; high starting torque; operation at relatively low speed; and easy adaptation to urban sites. These advantages may outweigh its low efficiency and make it suitable for small-scale power requirements such as pumping and rural electrification. This paper presented a study of the aerodynamic behaviour of a Savonius rotor, based on blade pressure measurements. A two-dimensional analysis method was used to determine the aerodynamic strengths, which leads to the Magnus effect and the generation of the vibrations on the rotor. The study explained the vibratory behaviour of the rotor and proposed an antivibration system to protect the machine. 14 refs., 1 tab., 9 figs.

  8. Mechanisms of activation of maternal behaviour in mammals

    OpenAIRE

    Poindron, Pascal

    2005-01-01

    International audience; In mammals, the activation of maternal behaviour depends on internal maternal factors related with parturition. The nature of these factors may vary between species, although oestradiol, foetus expulsion and intracerebral oxytocin are the most commonly encountered. They induce a period of specific receptivity to some sensory cues provided by the neonate. These cues (tactile, olfactory, auditory, ...) also vary between species. The interactions between the mother and he...

  9. Numerical simulation of the non-isothermal mechanical behaviour of soils

    OpenAIRE

    Laloui, Lyesse; Cekerevac, Cane

    2008-01-01

    Research interest in the thermo-mechanical behaviour of soils is growing as a result of an increasing number of geomechanical problems involving thermal effects. This paper concerns the constitutive modelling of non- isothermal mechanical behaviour of clayey soils. An elastoplastic model is extended to non-isothermal conditions to account for non-linearities and hardening that occurs as a result of heating of soils. This constitutive model includes evolution of the yield limit ...

  10. High degree of duodenal inflammation in Nigerians with functional dyspepsia

    Directory of Open Access Journals (Sweden)

    Nwokediuko SC

    2013-12-01

    Full Text Available Sylvester Chuks Nwokediuko,1 Uchenna N Ijoma,1 Olive Obienu,1 Gideon E Anigbo,1 Okechukwu Okafor21Department of Medicine, 2Department of Morbid Anatomy, University of Nigeria Teaching Hospital, Ituku/Ozalla Enugu, NigeriaBackground: Functional dyspepsia (FD is a heterogeneous disorder associated with diverse pathophysiological mechanisms, including immune activation and low-grade mucosal inflammation. Genetic factors, physiological functions, and environmental factors may determine the relative importance of various pathophysiological mechanisms. This study was designed to determine the histological alterations in the duodenal mucosa of Nigerian patients with FD.Methods: Consecutive patients with dyspepsia seen over a 27-month period in two gastrointestinal endoscopy facilities in Enugu, South-East Nigeria were further evaluated with upper gastrointestinal endoscopy and duodenal mucosal biopsies if no lesion was found in the upper gastrointestinal tract. Patients with heartburn and/or regurgitation who did not have any dyspeptic symptoms and did not have any lesion in the upper gastrointestinal tract on endoscopy were presumed to have non-erosive reflux disease (NERD and they served as controls. The control subjects also had duodenal biopsies. The histopathological findings in the cases and controls were compared.Results: There were 68 patients with FD and 52 patients with NERD. The total inflammatory score was 242 in FD and 66 in NERD (Mann-Whitney U =1168, P=0.0011. Similarly, the scores for chronic inflammation, gastric metaplasia, neutrophilic activity, eosinophilic infiltration, and Helicobacter pylori were significantly higher in FD than NERD.Conclusion: Functional dyspepsia is associated with a high degree of inflammation in the duodenal mucosa. This may reflect the high prevalence of gastrointestinal infections in a tropical environment such as Nigeria. These findings may have therapeutic potential that further studies might elucidate

  11. Modelling the thermo-mechanical volume change behaviour of compacted expansive clays

    CERN Document Server

    Tang, Anh-Minh; 10.1680/geot.2009.59.3.185

    2009-01-01

    Compacted expansive clays are often considered as a possible buffer material in high-level deep radioactive waste disposals. After the installation of waste canisters, the engineered clay barriers are subjected to thermo-hydro-mechanical actions in the form of water infiltration from the geological barrier, heat dissipation from the radioactive waste canisters, and stresses generated by clay swelling under almost confined conditions. The aim of the present work is to develop a constitutive model that is able to describe the behaviour of compacted expansive clays under these coupled thermo-hydro-mechanical actions. The proposed model is based on two existing models: one for the hydro-mechanical behaviour of compacted expansive clays and another for the thermo-mechanical behaviour of saturated clays. The elaborated model has been validated using the thermo-hydro-mechanical test results on the compacted MX80 bentonite. Comparison between the model prediction and the experimental data show that this model is able...

  12. Traumatic duodenal hematoma in the pediatric patient.

    Science.gov (United States)

    Winthrop, A L; Wesson, D E; Filler, R M

    1986-09-01

    Twenty children with duodenal hematomas secondary to blunt trauma were treated between 1953 and 1983. The duodenal injury was isolated in ten cases and associated with intra-abdominal injuries in the others. In ten, the duodenal injury was suspected on admission and the diagnosis was confirmed within 24 hours by radiographic contrast studies. All ten were managed successfully with nasogastric suction and intravenous fluids. Ten patients underwent laparotomy for increasing abdominal tenderness and guarding. An isolated duodenal hematoma was found in four and treated by evacuation and/or gastroenterostomy. In five of the remaining six surgical patients, all of whom had multiple intra-abdominal injuries, the duodenum was left untouched. Three of these patients had postoperative contrast studies that showed early resolution of the duodenal hematoma. No duodenal stricture or leak developed in any patient. The children with isolated duodenal hematomas who were treated conservatively had a mean hospital stay of six days, whereas those treated surgically had a mean stay of 17 days. The ten patients with multiple intra-abdominal injuries had a mean hospital stay of 32 days. In this group, eight required total parenteral nutrition or nasojejunal feeds for nutritional support. In these patients, an isolated duodenal hematoma resulted in minimal morbidity and nonoperative management was usually successful. The presence of associated intra-abdominal injuries was responsible for the prolonged hospitalization and delayed return of normal intestinal function in some patients.

  13. Duodenal Transection without Pancreatic Injury following Blunt ...

    African Journals Online (AJOL)

    Journal of Surgical Technique and Case Report | Jul-Dec 2014 | Vol-6 | Issue-2. 67. Duodenal Transection ... Early interventions in duodenal injuries have improved outcome. Here we report a ... developed abdominal pain along with single episode of ... challenge to the surgeon and failure to manage it properly can result in ...

  14. Duodenal polyposis secondary to portal hypertensive duodenopathy

    Institute of Scientific and Technical Information of China (English)

    Ananta; Gurung; Philip; E; Jaffe; Xuchen; Zhang

    2015-01-01

    Portal hypertensive duodenopathy(PHD) is a recognized, but uncommon finding of portal hypertension in cirrhotic patients. Lesions associated with PHD include erythema, erosions, ulcers, telangiectasia, exaggerated villous pattern and duodenal varices. However, duodenal polyposis as a manifestation of PHD is rare. We report a case of a 52-year-old man who underwent esophagogastroduodenoscopy and was found with multiple small duodenal polyps ranging in size from 1-8 mm. Biopsy of the representative polyps revealed polypoid fragments of duodenal mucosa with villiform hyperplasia lined by reactive duodenal/gastric foveolar epithelium and underlying lamina propria showed proliferating ectatic and congested capillaries. The features were diagnostic of polyps arising in the setting of PHD.

  15. Perforated duodenal ulcer: Emerging pattern

    Directory of Open Access Journals (Sweden)

    Murtaza Ali Asger Calcuttawala

    2014-01-01

    Full Text Available Background: A total of 27 patients of perforated duodenal ulcer admitted in our institution between December 2010 and November 2012 were treated and studied. Materials and Methods: All patients were diagnosed on the basis of clinical and radiological findings, exploratory laparotomy was performed and simple closure of perforation with placement of Graham′s omental patch was carried out. This was followed by triple regimen for Helicobacter pylori eradication. Results: All patients were male, maximum incidence (61.54% was noted in the age group of 21-30, ′O′ +ve blood group was most commonly observed in our patients. Eight patients had history suggestive of acute acid peptic disease. Mean time interval between the start of symptoms and surgery was 43 h. No morbidity except minimal pleural effusion was seen in one case. There was no mortality in our series. Conclusion: We conclude that although a number of definitive surgeries have been described for acid peptic disease, but the requirement of such procedures has come down due to increasing use of H. pylori eradication therapy and proton pump inhibitors. However, surgery for complications especially for duodenal ulcer perforation has not reduced concomitantly. Incidence is greater in young males.

  16. Exploring associations between self-regulatory mechanisms and neuropsychological functioning and driver behaviour after brain injury.

    Science.gov (United States)

    Rike, Per-Ola; Johansen, Hans J; Ulleberg, Pål; Lundqvist, Anna; Schanke, Anne-Kristine

    2016-04-11

    The objective of this prospective one-year follow-up study was to explore the associations between self-regulatory mechanisms and neuropsychological tests as well as baseline and follow-up ratings of driver behaviour. The participants were a cohort of subjects with stroke and traumatic brain injury (TBI) who were found fit to drive after a multi-disciplinary driver assessment (baseline). Baseline measures included neuropsychological tests and ratings of self-regulatory mechanisms, i.e., executive functions (Behavior Rating Inventory of Executive Function-Adult Version; BRIEF-A) and impulsive personality traits (UPPS Impulsive Behavior Scale). The participants rated pre-injury driving behaviour on the Driver Behaviour Qestionnaire (DBQ) retrospectively at baseline and after one year of post-injury driving (follow-up). Better performance on neuropsychological tests was significantly associated with more post-injury DBQ Violations. The BRIEF-A main indexes were significantly associated with baseline and follow-up ratings of DBQ Mistakes and follow-up DBQ Inattention. UPPS (lack of) Perseverance was significantly associated with baseline DBQ Inattention, whereas UPPS Urgency was significantly associated with baseline DBQ Inexperience and post-injury DBQ Mistakes. There were no significant changes in DBQ ratings from baseline (pre-injury) to follow-up (post-injury). It was concluded that neuropsychological functioning and self-regulatory mechanisms are related to driver behaviour. Some aspects of driver behaviour do not necessarily change after brain injury, reflecting the influence of premorbid driving behaviour or impaired awareness of deficits on post-injury driving behaviour. Further evidence is required to predict the role of self-regulatory mechanisms on driver behaviour and crashes or near misses.

  17. Multi-objective behavioural mechanisms are adopted by foraging animals to achieve several optimality goals simultaneously.

    Science.gov (United States)

    Wajnberg, Eric

    2012-03-01

    1. Animals foraging for resources are under a variety of selective pressures, and separate optimality models have been developed predicting the optimal reproductive strategies they should adopt. 2. In most cases, the proximate behavioural mechanisms adopted to achieve such optimality goals have been identified. This is the case, for example, for optimal patch time and sex allocation in insect parasitoids. However, behaviours modelled within this framework have mainly been studied separately, even though real animals have to optimize some behaviours simultaneously. 3. For this reason, it would be better if proximate behavioural rules were designed to attain several goals simultaneously. Despite their importance, such multi-objective proximate rules remain to be discovered. 4. Based on experiments on insect parasitoids that simultaneously examine their optimal patch time and sex allocation strategies, it is shown here that animals can adopt multi-objective behavioural mechanisms that appear consistent with the two optimal goals simultaneously. 5. Results of computer simulations demonstrate that these behavioural mechanisms are indeed consistent with optimal reproductive strategies and have thus been most likely selected over the course of the evolutionary time.

  18. Mechanical behaviour of engineering materials. Metals, ceramics, polymers, and composites

    Energy Technology Data Exchange (ETDEWEB)

    Roesler, Joachim; Baeker, Martin [TU Braunschweig (Germany). Inst. fuer Werkstoffe; Harders, Harald

    2007-07-01

    How do engineering materials deform when bearing mechanical loads? To answer this crucial question, the book bridges the gap between continuum mechanics and materials science. The different kinds of material deformation (elasticity, plasticity, fracture, creep, fatigue) are explained in detail. The book also discusses the physical processes occurring during the deformation of all classes of engineering materials (metals, ceramics, polymers, and composites) and shows how these materials can be strengthened to meet the design requirements. It provides the knowledge needed in selecting the appropriate engineering material for a certain design problem.

  19. Mechanical properties and thermal behaviour of LLDPE/MWNTs nanocomposites

    Directory of Open Access Journals (Sweden)

    Tai Jin-hua

    2012-12-01

    Full Text Available Multi-walled carbon nanotubes (MWNTs were incorporated into a linear low-density polyethylene (LLDPE matrix through using screw extrusion and injection technique. The effect of different weight percent loadings of MWNTs on the morphology, mechanical, and thermal of LLDPE/MWNTs nanocomposite had been investigated. It was found that, at low concentration of MWNTs, it could uniformly disperse into a linear low-density polyethylene matrix and provide LLDPE/MWNTs nanocomposites much improved mechanical properties. Thermal analysis showed that a clear improvement of thermal stability for LLDPE/MWNTs nanocomposites increased with increasing MWNTs content.

  20. MECHANICAL BEHAVIOUR OF THERMOPLASTIC STARCH/MONTMORILLONITE/ALUMINA TRIHYDRATE NANOCOMPOSITES

    Directory of Open Access Journals (Sweden)

    FIRNAAZ AHAMED

    2016-09-01

    Full Text Available Thermoplastic starch (TPS is a biodegradable biopolymer that has exhibited great prospects to replace conventional synthetic polymers in commercial applications. However, one of the most critical limitations of TPS is the lack of crucial mechanical properties. This study proposes the novel combination of cassava starch, montmorillonite nanoclay (MMT and alumina trihydrate (ATH in the form of a nanocomposite which is expected to demonstrate improved mechanical properties. The nanocomposites were processed through melt-extrusion in twin-screw extruder where loadings of MMT and ATH were varied between 1 to 6 wt% and 26 to 37 wt%, respectively. The mechanical properties were evaluated through tensile testing according to ASTM D882. The fractured surfaces of the specimens were evaluated using scanning electron microscopy (SEM to further validate the mechanical properties of the nanocomposites. The melt viscosity and processability of the nanocomposites were also evaluated through melt flow index (MFI testing according to ASTM D1238. Presence of MMT and ATH in TPS demonstrated increase in Young’s modulus, maximum tensile stress and decrease in elongation at break up to 57.6 MPa, 5.1 MPa and 39.2%, respectively. In the presence of ATH, increase in loading of MMT continued to improve Young’s modulus and maximum tensile stress while declining elongation at break. Without ATH, MMT was only capable of improving mechanical strength up to a loading of 3 wt% where adverse effects were observed when the loading was further increased to 6 wt%. Increase in loadings of both MMT and ATH, simultaneously were found to depreciate the MFI and thus, the processability of the nanocomposites.

  1. On the hydro-mechanical behaviour of MX80 bentonite-based materials

    Directory of Open Access Journals (Sweden)

    Yu-Jun Cui

    2017-06-01

    Full Text Available Bentonite-based materials have been considered in many countries as engineered barrier/backfilling materials in deep geological disposal of high-level radioactive waste. During the long period of waste storage, these materials will play an essential role in ensuring the integrity of the storage system that consists of the waste canisters, the engineered barrier/backfill, the retaining structures as well as the geological barrier. Thus, it is essential to well understand the hydro-mechanical behaviours of these bentonite-based materials. This review paper presents the recent advances of knowledge on MX80 bentonite-based materials, in terms of water retention properties, hydraulic behaviour and mechanical behaviour. Emphasis is put on the effect of technological voids and the role of the dry density of bentonite. The swelling anisotropy is also discussed based on the results from swelling tests with measurements of both axial and radial swelling pressures on a sand-bentonite mixture compacted at different densities. Microstructure observation was used to help the interpretation of macroscopic hydro-mechanical behaviour. Also, the evolution of soil microstructure thus the soil density over time is discussed based on the results from mock-up tests. This evolution is essential for understanding the long-term hydro-mechanical behaviour of the engineered barrier/backfill.

  2. Mechanical behaviour of ferritic ODS steels - Temperature dependancy and anisotropy

    Science.gov (United States)

    Fournier, B.; Steckmeyer, A.; Rouffie, A.-L.; Malaplate, J.; Garnier, J.; Ratti, M.; Wident, P.; Ziolek, L.; Tournie, I.; Rabeau, V.; Gentzbittel, J. M.; Kruml, T.; Kubena, I.

    2012-11-01

    Ferritic 14%Cr and 18%Cr ODS steels produced at CEA in round bars or plates were tested mechanically. The present paper reports results obtained in tension, impact, fatigue, creep and toughness tests. These tests were carried out at various temperatures and in different directions. These materials show a pronounced anisotropy at all tested temperatures. No matter the loading, the transversal direction is always found to be far less resistant than the longitudinal one. This anisotropy is mainly observed in terms of damage mechanisms, with intergranular fracture preferentially occurring along the extrusion direction. This intergranular fracture mode leads to very low and anisotropic toughness values and to the absence of tertiairy creep stage, pointing out the unstable nature of fracture, even at high temperature. The unrealistically high values of the Norton exponent measured in creep suggests the existence of a threshold stress, which is consistent with the mainly kinematic nature of the stress as revealed by fatigue tests.

  3. Adenocarcinoma of the Minor Duodenal Papilla: Report of a Case

    Directory of Open Access Journals (Sweden)

    Kazuhiro Takami

    2011-04-01

    Full Text Available An 81-year-old male was found to have a duodenal tumor by screening upper gastrointestinal endoscopy. The tumor was located in the minor duodenal papilla. Pathological examination of the biopsy specimen revealed adenocarcinoma, and endoscopic ultrasound showed an elevated hypoechoic mass in the minor duodenal papilla. The preoperative diagnosis was therefore considered to be either adenocarcinoma of the minor duodenal papilla or duodenal cancer. We performed a subtotal stomach-preserving pancreaticoduodenectomy. Histopathological examination of the resected specimen showed the tumor cells to be primarily located in the submucosa of the minor duodenal papilla, with slight invasion into the pancreatic parenchyma through the accessory pancreatic duct. We therefore diagnosed a primary adenocarcima of the minor duodenal papilla. Adenocarcinoma of the minor duodenal papilla is considered to be a rare disease, but it may be underestimated because of the difficulty in distinguishing advanced adenocarcinoma of the minor duodenal papilla from primary duodenal cancer and cancer of the pancreatic head.

  4. Mechanical behaviour of copper 15% volume niobium microcomposite wires

    Directory of Open Access Journals (Sweden)

    Marcello Filgueira

    2001-01-01

    Full Text Available Cu-Nb microcomposites are attractive in magnet pulsed field technology applications due to their anomalous mechanism of mechanical strength and high electrical conductivity. In this sense, recently it was conceived the use of Cu 15% vol. Nb wires to operate as a high tensile strength cable for a diamond cutting tool (diamond wires for marble and granite slabbing. The multifilamentary Cu 15% vol. Nb composite was obtained using a new processing route, starting with niobium bars bundled into copper tubes, without arc melting. Cold working techniques, such as swaging and wire drawing, combined with heat treatments such as sintering and annealing, and tube restacking were employed. The tensile property of the composite was measured as a function of the niobium filaments dimensions and morphology into the copper matrix, in the several processing steps. An ultimate tensile strength (UTS of 960 MPa was obtained for an areal reduction (R = Ao/A, with Ao-initial cross section area, and A-final cross section area of 4x10(8 X, in which the niobium filaments reached thickness less than 20 nm. The anomalous mechanical strength increase is attributed to the fact that the niobium filaments acts as a barrier to copper dislocations.

  5. Acute Necrotizing Esophagitis Followed by Duodenal Necrosis.

    Science.gov (United States)

    Del Hierro, Piedad Magdalena

    2011-12-01

    Acute Necrotizing Esophagitis is an uncommon pathology, characterized by endoscopic finding of diffuse black coloration in esophageal mucosa and histological presence of necrosis in patients with upper gastrointestinal bleeding. The first case of acute necrotizing esophagitis followed by duodenal necrosis, in 81 years old woman with a positive history of Type 2 Diabetes Mellitus, Hypertension, and usual intake of Nonsteroidal Anti-inflammatory drugs, is reported. Although its etiology remains unknown, the duodenal necrosis suggests that ischemia could be the main cause given that the branches off the celiac axis provide common blood supply to the distal esophageal and duodenal tissue. The massive gastroesophagic reflux and NSAID intake could be involved.

  6. [ASSOCIATION OF DUODENAL DIVERTICULUM PRESENCE WITH CHOLEDOCHOLITHIASIS

    Science.gov (United States)

    Machado Mayurí, Alberto; Gómez, Aldo; Yriberry, Simón; Valdiviezo, Alfredo; Lozano, Adelina; Villena, Ovidio

    1998-01-01

    OBJECTIVES: The aim of this study was to investigate in aretrospective way the frequency of duodenal diverticulum and its association with choledocholithiasis. Methods:This study included 2728 consecutive patients who underwent ERCP during the period 1993-1997. Duodenal diverticulum was discovered in 122 cases (4.5%). In 22 patients cannulation was not achieved since it was not technically possible. Results: In 100 patients with successful cannulation, 54 cases with juxtapapillary diverticulum were encountered associated with choledocholithiasis. CONCLUSION: These data suggestthat duodenal diverticulum is associated with choledocholithiasis.

  7. Duodenal Perforation Precipitated by Scrub Typhus.

    Science.gov (United States)

    Rajat, Raghunath; Deepu, David; Jonathan, Arul Jeevan; Prabhakar, Abhilash Kundavaram Paul

    2015-01-01

    Scrub typhus is an acute febrile illness usually presenting with fever, myalgia, headache, and a pathognomonic eschar. Severe infection may lead to multiple organ failure and death. Gastrointestinal tract involvement in the form of gastric mucosal erosions and ulcerations owing to vasculitis resulting in gastrointestinal bleeding is common. This process may worsen a pre-existent asymptomatic peptic ulcer, causing duodenal perforation, and present as an acute abdomen requiring surgical exploration. We report the case of a patient with no previous symptoms or risk factors for a duodenal ulcer, who presented with an acute duodenal perforation, probably precipitated by scrub typhus infection.

  8. Duodenal perforation precipitated by scrub typhus

    Directory of Open Access Journals (Sweden)

    Raghunath Rajat

    2015-01-01

    Full Text Available Scrub typhus is an acute febrile illness usually presenting with fever, myalgia, headache, and a pathognomonic eschar. Severe infection may lead to multiple organ failure and death. Gastrointestinal tract involvement in the form of gastric mucosal erosions and ulcerations owing to vasculitis resulting in gastrointestinal bleeding is common. This process may worsen a pre-existent asymptomatic peptic ulcer, causing duodenal perforation, and present as an acute abdomen requiring surgical exploration. We report the case of a patient with no previous symptoms or risk factors for a duodenal ulcer, who presented with an acute duodenal perforation, probably precipitated by scrub typhus infection.

  9. Ampullary duodenal diverticulum and cholangitis

    Directory of Open Access Journals (Sweden)

    Joaquim Mendes Castilho Netto

    Full Text Available CONTEXT: Ampullary duodenal diverticulum complicated by cholangitis is little known in clinical practice, especially when there are no gallstones in the common bile duct or there is no biliary tree ectasia or hyperamylasemia. A case of this association is presented, in which the surgical treatment was a biliary-enteric bypass. CASE REPORT: A 74-year-old diabetic white woman was admitted to the Taubaté University Hospital, complaining of pain in the right upper quadrant, jaundice and fever with chills (Charcot's triad. She had had cholecystectomy 30 years earlier. She underwent clinical treatment with parenteral hydration, insulin, antibiotics and symptomatic drugs. Imaging examinations were provided for diagnosis: ultrasound, computed tomography and endoscopic retrograde cholangiopancreatography. The surgical treatment consisted of choledochojejunostomy utilizing a Roux-en-y loop. The postoperative period progressed without incidents, and a DISIDA scan demonstrated the presence of dynamic biliary excretion. The patient remained asymptomatic when seen at outpatient follow-up.

  10. Emerging complexity in a simple model of the mechanical behaviour of rocks

    CERN Document Server

    Amitrano, David

    2004-01-01

    We propose a mechanical model for the behaviour of rocks based on progressive damage at the elementary scale and elastic interaction. It allows us to simulate several experimental observations: mechanical behaviour ranging from brittle to ductile, fractal structure of the damage, powerlaw distribution of the damage avalanches. These macroscopic properties are not incorporated at the elementary scale, but are the results of the interaction between elements. This emerging complexity permits us to consider the strain rock process as a complex system characterized by non-linear dynamics.

  11. Endoscopic duodenal biopsy in children

    Directory of Open Access Journals (Sweden)

    El Mouzan Mohammad

    2006-01-01

    Full Text Available Background: Biopsy of the small bowel is frequently obtained by endoscopic forceps instead of the classical suction capsule, yet reports from developing countries are scarce. Aim of the study: to report our experience on the diagnostic value of this procedure in our community. Patients and methods: A retrospective analysis of all endoscopic duodenal biopsies (EDB, performed on all patients below 18 years of age. Data retrieved from the records included age, gender, nationality, indication for biopsy, the endoscopic findings, and the results of histopathology. Results: From 1993 to 2002, 241 endoscopic biopsies were performed on 241 consecutive children. Most of the children (96% were Saudi nationals, the age range between six weeks to 18 years, and male to female ratio was 0.7: 1. All of the biopsy material was adequate for routine histopathology. The commonest indications for biopsy were short stature and chronic diarrhea in 116/241 (48% and 102/241 (43% of the children respectively. Refractory rickets accounted for 11/241 (5% of the indications. The prevalence of villous atrophy was highest in children presenting with chronic diarrhea (40%, compared to short stature (22%. Other less common, but important findings were villous atrophy in three unusual conditions (one refractory rickets, one unexplained anemia, and one polyendocrinopathy, two cases of intestinal Giardia lamblia infestation, three cases of intestinal lymphangiectasis and one case of Mycobacterium avium intracellulare. Unexpected endoscopic findings were documented in 34/241 (14% of the children. Conclusions: Endoscopic duodenal biopsy is adequate not only for the diagnosis of villous atrophy, but also for the detection of other gastroenteropathies. Accordingly, when expertise and equipments are available, EDB should be the procedure of choice not only in industrialized but also in developing countries.

  12. Mechanical behaviour of new zirconia-hydroxyapatite ceramic materials

    Energy Technology Data Exchange (ETDEWEB)

    Delgado, J.A.; Morejon, L. [La Habana Univ. (Cuba). Centro de Biomateriales; Martinez, S. [Barcelona Univ. (Spain). Dept. Cristallografia, Mineralogia; Ginebra, M.P.; Carlsson, N.; Fernandez, E.; Planell, J.A. [Universidad Politecnica de Cataluna, Barcelona (Spain). CREB; Clavaguera-Mora, M.T.; Rodriguez-Viejo, J. [Universitat Autonoma de Barcelona (Spain). Dept. de Fisica

    2001-07-01

    In this work a new zirconia-hydroxyapatite ceramic material was obtained by uniaxial pressing and sintering in humid environment. The powder X-ray diffraction (XRD) patterns and infrared spectra (FT-IR) showed that the hydroxyapatite (HA) is the only calcium phosphate phase present. The fracture toughness for HA with 20 wt.% of magnesia partially stabilised zirconia (Mg-PSZ) was around 2.5 times higher than those obtained for HA pure, also the highest value of bending strength (160 MPa) was obtained for material reinforced with Mg-PSZ. For the MgPSZ-HA (20%) the fracture mechanism seems to be less transgranular. (orig.)

  13. Thermo-Mechanical Behaviour of Flax-Fibre Reinforced Epoxy Laminates for Industrial Applications

    Directory of Open Access Journals (Sweden)

    Giuseppe Pitarresi

    2015-11-01

    Full Text Available The present work describes the experimental mechanical characterisation of a natural flax fibre reinforced epoxy polymer composite. A commercial plain woven quasi-unidirectional flax fabric with spun-twisted yarns is employed in particular, as well as unidirectional composite panels manufactured with three techniques: hand-lay-up, vacuum bagging and resin infusion. The stiffness and strength behaviours are investigated under both monotonic and low-cycle fatigue loadings. The analysed material has, in particular, shown a typical bilinear behaviour under pure traction, with a knee yield point occurring at a rather low stress value, after which the material tensile stiffness is significantly reduced. In the present work, such a mechanism is investigated by a phenomenological approach, performing periodical loading/unloading cycles, and repeating tensile tests on previously “yielded” samples to assess the evolution of stiffness behaviour. Infrared thermography is also employed to measure the temperature of specimens during monotonic and cyclic loading. In the first case, the thermal signal is monitored to correlate departures from the thermoelastic behaviour with the onset of energy loss mechanisms. In the case of cyclic loading, the thermoelastic signal and the second harmonic component are both determined in order to investigate the extent of elastic behaviour of the material.

  14. Investigating the time-dependent behaviour of Boom clay under thermo-mechanical loading

    CERN Document Server

    Cui, Yu-Jun; Tang, Anh-Minh; Delage, Pierre; Li, Xiang-Ling; 10.1680/geot.2009.59.4.319

    2009-01-01

    Among the various laboratory studies to investigate the Thermo-Hydro-Mechanical (THM) behaviour of Boom clay, relatively few were devoted to the time dependent behaviour, limiting any relevant analysis of the long-term behaviour of the disposal facility. The present work aims at investigating the time-dependent behaviour of Boom clay under both thermal and mechanical loading. High-pressure triaxial tests at controlled temperatures were carried out for this purpose. The tests started with constant-rate thermal and/or mechanical consolidation and ended with isobar heating and/or isothermal compression at a constant stress rate or by step loading. Significant effects of temperature as well as of compression and heating rates were observed on the volume change behaviour. After being loaded to a stress lower than the pre-consolidation pressure (5 MPa) at a low temperature of 25\\degree C and at a rate lower than 0.2 kPa/min, the sample volume changes seemed to be quite small, suggesting a full dissipation of pore w...

  15. Duodenal diverticulitis. computed tomography findings; Diverticulities duodenal. Hallazgos en la TC

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, E.; Martin, S.; Garcia, J.; Dominguez, A. [Hospital Ramon y Cajal. Madrid (Spain)

    2001-07-01

    Duodenal diverticular occur very frequently among the general public. However, duodenal diverticulitis is a very uncommon clinical entity, the diagnosis of which requires radiological studies since the clinical signs cam mimic a great number of disease processes with different treatments. We present a case of duodenal diverticulitis in which the diagnosis according to ultrasound and computed tomography (CT) studies was confirmed intraoperatively. We also review the few cases of this entity reported in the literature. The CT findings are highly suggestive of duodenal diverticulitis given their similarity to those associated with diverticulitis at other sites. (Author) 5 refs,.

  16. Isotropic incompressible hyperelastic models for modelling the mechanical behaviour of biological tissues: a review.

    Science.gov (United States)

    Wex, Cora; Arndt, Susann; Stoll, Anke; Bruns, Christiane; Kupriyanova, Yuliya

    2015-12-01

    Modelling the mechanical behaviour of biological tissues is of vital importance for clinical applications. It is necessary for surgery simulation, tissue engineering, finite element modelling of soft tissues, etc. The theory of linear elasticity is frequently used to characterise biological tissues; however, the theory of nonlinear elasticity using hyperelastic models, describes accurately the nonlinear tissue response under large strains. The aim of this study is to provide a review of constitutive equations based on the continuum mechanics approach for modelling the rate-independent mechanical behaviour of homogeneous, isotropic and incompressible biological materials. The hyperelastic approach postulates an existence of the strain energy function--a scalar function per unit reference volume, which relates the displacement of the tissue to their corresponding stress values. The most popular form of the strain energy functions as Neo-Hookean, Mooney-Rivlin, Ogden, Yeoh, Fung-Demiray, Veronda-Westmann, Arruda-Boyce, Gent and their modifications are described and discussed considering their ability to analytically characterise the mechanical behaviour of biological tissues. The review provides a complete and detailed analysis of the strain energy functions used for modelling the rate-independent mechanical behaviour of soft biological tissues such as liver, kidney, spleen, brain, breast, etc.

  17. Mechanical behaviour and formation process of silkworm silk gut.

    Science.gov (United States)

    Cenis, José L; Madurga, Rodrigo; Aznar-Cervantes, Salvador D; Lozano-Pérez, A Abel; Marí-Buyé, Núria; Meseguer-Olmo, Luis; Plaza, Gustavo R; Guinea, Gustavo V; Elices, Manuel; Del Pozo, Francisco; Pérez-Rigueiro, José

    2015-12-14

    High performance silk fibers were produced directly from the silk glands of silkworms (Bombyx mori) following an alternative route to natural spinning. This route is based on a traditional procedure that consists of soaking the silk glands in a vinegar solution and stretching them by hand leading to the so called silkworm guts. Here we present, to the authors' best knowledge, the first comprehensive study on the formation, properties and microstructure of silkworm gut fibers. Comparison of the tensile properties and microstructural organization of the silkworm guts with those of naturally spun fibers allows gain of a deeper insight into the mechanisms that lead to the formation of the fiber, as well as the relationship between the microstructure and properties of these materials. In this regard, it is proved that an acidic environment and subsequent application of tensile stress in the range of 1000 kPa are sufficient conditions for the formation of a silk fiber.

  18. Identification of the mechanical behaviour of biopolymer composites using multistart optimisation technique

    KAUST Repository

    Brahim, Elhacen

    2013-10-01

    This paper aims at identifying the mechanical behaviour of starch-zein composites as a function of zein content using a novel optimisation technique. Starting from bending experiments, force-deflection response is used to derive adequate mechanical parameters representing the elastic-plastic behaviour of the studied material. For such a purpose, a finite element model is developed accounting for a simple hardening rule, namely isotropic hardening model. A deterministic optimisation strategy is implemented to provide rapid matching between parameters of the constitutive law and the observed behaviour. Results are discussed based on the robustness of the numerical approach and predicted tendencies with regards to the role of zein content. © 2013 Elsevier Ltd.

  19. Thermal cycling, oxidation behaviour and mechanical properties of graded and duplex PSZ TBC coatings

    Energy Technology Data Exchange (ETDEWEB)

    Musil, J. [SKODA, Plzen (Czech Republic); Alaya, M.; Oberacker, R. [Univ. of Karlsruhe (Germany)

    1995-07-01

    Plasma sprayed duplex and graded ZrO{sub 2} thermal barrier coatings (TBCs) on an Inconel 617 substrate with a NiCrAlY bond coat were investigated and compared with regard to their thermal cycling, oxidation behaviour and mechanical properties. On the basis of FE - calculations the stress distribution within thermally cycled coating systems was analyzed. The calculations show that the graded coating structure relaxes considerably the stresses resulting from the internal constraint due to thermal expansion difference between both metallic and ceramic materials and hence must lead to a better thermal cycling behaviour of the graded TBC systems. Mechanical tests confirm it. However, taking into account their poor oxidation behaviour, the lifetime of duplex TBC systems which are under steady-state thermal load conditions is much higher than that of graded ones.

  20. Mechanical behaviour of tape springs used in the deployment of reflectors around a solar panel

    Science.gov (United States)

    Dewalque, Florence; Collette, Jean-Paul; Brüls, Olivier

    2016-06-01

    In order to increase the production of power on small satellites, solar panels are commonly deployed and, in some cases, reflectors are added to improve the concentration factor on solar cells. In this work, reflectors are deployed by the means of compliant mechanisms known as tape springs. Their attractive characteristics are, among others, their passive behaviour, their self-locking capacity, their elastic deformations and their robustness. However, their mechanical behaviour is highly nonlinear and requires thorough analyses in order to develop predictive numerical models. It is shown here through parametric studies that the nonlinear behaviour of a tape spring is mainly governed by its geometry. Thus, for each specific application, its dimensions can be determined in order to minimise two critical features: the maximum stress affecting the structure and the maximum motion amplitude during deployment. In this paper, an optimisation procedure is proposed to meet these requirements.

  1. [Persistent duodenal septum in an adult].

    Science.gov (United States)

    Helwing, E; Echtermeyer, V; Otten, G

    1977-02-01

    A case of duodenal obstruction by a congenital duodenal web in a 34-year-old woman is presented. A mucosal diaphragm obstructed the duodenum. It showed an excentric opening of 0.8 cm diameter, but the dilated diaphragm caused a total stop during the last months. Despite a typical history, exact X-ray, and endoscopic examination, the correct preoperative diagnosis was not found, because nobody thought it possible, that a mucosal diapharm of the duodenum could persist for 34 years.

  2. Modeling of the mechanical behaviour of welded structures: behaviour laws and rupture criteria; Modelisation du comportement mecanique de structures soudees: lois de comportement et criteres de rupture

    Energy Technology Data Exchange (ETDEWEB)

    Paris, T.; Delaplanche, D. [CEA Valduc, Laboratoire Calcul et Simulations, 21120 Is-sur-Tille (France); Saanouni, K. [LASMIS-CNRS-FRE 2719, Universite de Technologie de Troyes BP 2060 - 10010 Troyes - (France)

    2006-07-01

    In the framework of the technological developments carried out in the CEA, the analysis of the mechanical behaviour of the heterogeneous welded bonds Ta/TA6V is a main preoccupation. Indeed, the welding of these two materials which cannot be distinguished by their mechanical and thermal properties induces strong microstructural heterogeneities in the melted zone. In order to characterize the behaviour of the welded joints and to develop a model of mechanical behaviour, a four points bending test on a notched specimen has been developed and implemented. This new test has allowed to obtain a macroscopic response of strength-displacement type but to analyze too more finely, with an optical extensometry and images correlation method, the influence of the heterogeneities on the local deformation of the welded joint. The confrontation of these results to a metallurgical study allows to validate the first conclusions deduced of the mechanical characterization tests and to conclude as for the local mechanisms governing the behaviour and the damage of the melted zone. The mechanical behaviour can be restored by an elasto-viscoplastic model with isotropic and non linear kinematic strain hardening coupled to this damage. The proposed model allows to identify the macroscopic behaviour of the weld bead. (O.M.)

  3. Tribo-mechanical behaviour of SiC filled glass-epoxy composites at ...

    African Journals Online (AJOL)

    Tribo-mechanical behaviour of SiC filled glass-epoxy composites at elevated temperatures. ... Username, Password, Remember me, or Register ... For instance, the introduction of ceramics such (SiC, Al2O3, TiC, etc.) as within the matrix ...

  4. Multiple early gastric cancer with duodenal invasion

    Directory of Open Access Journals (Sweden)

    Okino Tetsuya

    2007-10-01

    Full Text Available Abstract Background Early gastric cancers with duodenal invasion are rare, and no previous case of multiple early gastric cancer, one invading the duodenal bulb, has been reported. Case presentation A 79-year-old woman was investigated for upper abdominal discomfort. Endoscopic examination revealed an irregular nodulated lesion in the antrum area, and a reddish aggregated-type semi-circumferential nodulated lesion extending from the prepyloric area to the duodenal bulb through the normal mucosa with the antrum lesion. Biopsy revealed a tubular adenoma for the antrum lesion and a well-differentiated tubular adenocarcinoma for the prepyloric lesion. Distal gastrectomy with sufficient duodenal resection was performed. Microscopically, the antrum lesion appeared as a papillary adenocarcinoma, and the prepyloric lesion as a mainly papillary adenocarcinoma which partially invaded the submucosa without any sequential elongation for endoscopic findings. The lesion extended into the duodenal bulb, and was 12 mm in length from the oral end of Brunner's gland's area and limited within the duodenal mucosa. Conclusion Here, we present an unusual case of multiple early gastric cancer, one of which invaded the duodenum with relative wide mucosal spreading. This case illustrates that even early stage cancers located in the gastric antrum, particularly in the prepyloric area can invade the duodenum directly.

  5. Thermal stresses in hexagonal materials - heat treatment influence on their mechanical behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Gloaguen, D.; Freour, S.; Guillen, R.; Royer, J. [Nantes Univ., GeM, Institut de Recherche en Genie Civil et Mecanique, Ecole Centrale de Nantes, UMR CNRS 6183, 44 (France); Francois, M. [Universite de Technologie de Troyes, Lab. des Systemes Mecaniques et d' Ingenierie Simultanee (LASMIS), 10 - Troyes (France)

    2004-12-01

    Internal stresses due to anisotropic thermal and plastic properties were investigated in rolled zirconium and titanium. The thermal stresses induced by a cooling process were predicted using a self-consistent model and compared with experimental results obtained by X-ray diffraction. The study of the elastoplastic response during uniaxial loading was performed along the rolling and the transverse direction of the sheet, considering the influence of the texture and the thermal stresses on the mechanical behaviour. An approach in order to determine the thermal behaviour of phases embedded in two-phase materials is also presented. For zirconium, the residual stresses due to thermal anisotropy are rather important (equivalent to 35% of the yield stress) and consequently they play an important role on the elastoplastic transition contrary to titanium. The study of two-phase material shows the influence and the interaction of the second phase on the thermal behaviour in the studied phase.

  6. A cell-based computational model of early embryogenesis coupling mechanical behaviour and gene regulation.

    Science.gov (United States)

    Delile, Julien; Herrmann, Matthieu; Peyriéras, Nadine; Doursat, René

    2017-01-23

    The study of multicellular development is grounded in two complementary domains: cell biomechanics, which examines how physical forces shape the embryo, and genetic regulation and molecular signalling, which concern how cells determine their states and behaviours. Integrating both sides into a unified framework is crucial to fully understand the self-organized dynamics of morphogenesis. Here we introduce MecaGen, an integrative modelling platform enabling the hypothesis-driven simulation of these dual processes via the coupling between mechanical and chemical variables. Our approach relies upon a minimal 'cell behaviour ontology' comprising mesenchymal and epithelial cells and their associated behaviours. MecaGen enables the specification and control of complex collective movements in 3D space through a biologically relevant gene regulatory network and parameter space exploration. Three case studies investigating pattern formation, epithelial differentiation and tissue tectonics in zebrafish early embryogenesis, the latter with quantitative comparison to live imaging data, demonstrate the validity and usefulness of our framework.

  7. Size-Dependent Melting Behaviour of Nanometre-Sized Pb Particles Studied by Dynamic Mechanical Analysis

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao-Min; FEI Guang-Tao; CUI Ping

    2006-01-01

    Nanometre-sized (hereafter nano-)Pb particles embedded in an Al matrix are prepared by ball milling.It is found that the size of nano-Pb particles was decreased with increasing milling time.The melting behaviour of nano-Pb particles embedded in the Al matrix is studied by means of dynamic mechanical analysis,and a single internal friction peak in the vicinity of Pb melting temperature is observed.The onset temperature of the peak moves to lower temperature with the decrease of particles size and the internal friction peak height is increased,which indicates a size-dependent melting behaviour of nano-Pb particles.It is suggested that the size-dependent melting behaviour is associated with surface melting.

  8. A cell-based computational model of early embryogenesis coupling mechanical behaviour and gene regulation

    Science.gov (United States)

    Delile, Julien; Herrmann, Matthieu; Peyriéras, Nadine; Doursat, René

    2017-01-01

    The study of multicellular development is grounded in two complementary domains: cell biomechanics, which examines how physical forces shape the embryo, and genetic regulation and molecular signalling, which concern how cells determine their states and behaviours. Integrating both sides into a unified framework is crucial to fully understand the self-organized dynamics of morphogenesis. Here we introduce MecaGen, an integrative modelling platform enabling the hypothesis-driven simulation of these dual processes via the coupling between mechanical and chemical variables. Our approach relies upon a minimal `cell behaviour ontology' comprising mesenchymal and epithelial cells and their associated behaviours. MecaGen enables the specification and control of complex collective movements in 3D space through a biologically relevant gene regulatory network and parameter space exploration. Three case studies investigating pattern formation, epithelial differentiation and tissue tectonics in zebrafish early embryogenesis, the latter with quantitative comparison to live imaging data, demonstrate the validity and usefulness of our framework.

  9. Ultrastructural changes in non-specific duodenitis

    Institute of Scientific and Technical Information of China (English)

    Cheng-Xin Wang; Li-Jiang Liu; Jing Guan; Xiao-Ling Zhao

    2005-01-01

    AIM: To investigate the ultrastructural and morphological changes of non-specific duodenitis (NSD) in an attempt to grade them according to the extent of the lesions.METHODS: Biopsies were taken from the mucosa of duodenal bulb of 44 patients selected from the patients undergoing upper gastrointestinal endoscopy for epigastric discomforts. From each patient, two pinch biopsies on the same area were obtained from duodenal bulb. One was for scanning electron microscopy and the other was stained with hematoxylin-eosin, Warthin-Starry silver and both were then examined under light microscope. A total of 12 specimens (three from each degree of the normal and Ⅰ-Ⅲ of NSD diagnosed and graded by histology) selected from the 44patients were dehydrated, critical point dried, coated with gold palladium and examined under a JEOL JSM-30 scanning electron microscope (SEM) at 20 kV.RESULTS: According to the ultrastructural morphologic changes, non-specific duodenitis was divided into normal (as control group), mild, moderate and severe degrees according to results of SEM. The normal villi of duodenal bulb were less than 0.2 mm. There were inflammation cells,occasionally red blood cells and macrophages on the mucosal epithelial surface. Erosion and desquamation of epithelium could be seen. Three cases (25%, 3/12) had gastric metaplasia and Helicobacter pylori(H pylori) infection could be found in 5 cases (41.67%, 5/12) in duodenal bulb mucosa. The most distinctive feature was the ulcer-like defect on the surface of epithelial cells.CONCLUSION: Non-specific duodenitis is a separate entity disease caused by different factors. SEM is of value as an aid in the diagnosis of mucosal diseases of duodenum.

  10. Mechanical behaviour of cross-country ski racing poles during double poling.

    Science.gov (United States)

    Stöggl, Thomas; Karlöf, Lars

    2013-11-01

    The purpose of this study was to evaluate the behaviour of cross-country ski poles during double poling on a treadmill using three-dimensional kinematics. The results were compared with standard laboratory tests of the pole manufacturers. A total of 18 skiers were analysed at two speeds (85% and 95% of the maximal speed) at grades of 1.5% and 7%. Variables describing cycle characteristics, bending stiffness, bending behaviour, and trajectories of the pole markers were analysed. Triangular-shaped poles demonstrated the greatest stiffness and lowest variability in maximal bending. Softer poles demonstrated greater variability in bending behaviour and lost ground contact at high skiing speeds, which for some skiers resulted in failure to complete high-speed tests. Considerable variations in pole behaviour for similar poles between skiers were observed, which might be attributed to differences in technique, indicating that mechanical properties of the poles did not exclusively determine pole behaviour in the dynamic situation. The greatest magnitude of pole bending was in the middle part of the pole, which differed from the standard static pole analysis of the manufacturer. Increases in grade demonstrated the greatest effect on pole bending. Distinct differences from the pole manufacturers' laboratory measures were apparent, suggesting that basic pole testing might be adapted.

  11. On the origins of the anisotropic mechanical behaviour of extruded AA2017 aluminium alloy

    Indian Academy of Sciences (India)

    A MAY

    2017-04-01

    This paper presents some experimental investigations about the origins of the anisotropic behaviour in cyclic loadings of AA2017 aluminium alloy. In the first step, fatigue damage evolutions were quantified for controlled proportional cyclic loadings in axial and shear directions. In this stage, the aim was to confirm the anisotropic mechanical behaviour, which has recently been revealed. To this end, severalmodels of fatigue damage quantification were used. After a comparative study between the obtained results we confirmed the anisotropic nature of the used material. In the second step, microstructural investigations were performed in order to understand the origins of the anisotropic mechanical behaviour. We used scanning electron microscopy to analyse phases and precipitates inthe transversal and the longitudinal sections. It was deduced that the structure and the morphology of these entities are responsible for the anisotropic behaviour of the used aluminium alloy. Moreover, the results obtained usingKikushi diagrams, poles figure and inverse poles figures have also confirmed these conclusions. Indeed, these results have shown great differences in crystallographic texture of the material.

  12. Non-avoidance behaviour in enchytraeids to boric acid is related to the GABAergic mechanism.

    Science.gov (United States)

    Bicho, Rita C; Gomes, Susana I L; Soares, Amadeu M V M; Amorim, Mónica J B

    2015-05-01

    Soil invertebrates, e.g. enchytraeids, are known to be able to avoid unfavourable conditions, which gives them an important ecological advantage. These organisms possess chemoreceptors that can detect stressors, which in turn activate responses such as avoidance behaviour. We studied the avoidance behaviour in response to boric acid (BA) using enchytraeids. Results showed not only no avoidance, but that increasing concentrations seemed to have an "attraction" effect. To study the underlying mechanism, a selection of genes targeting for neurotransmission pathways (acetylcholinesterase (AChE) and gamma-aminobutyric acid receptor (GABAr)) were quantified via quantitative real-time polymerase chain reaction (qPCR). Evidences were that BA is neurotoxic via the GABAergic system mechanism where it acts as a GABA-associated protein receptor (GABAAR) antagonist possibly causing anaesthetic effects. This is the first time that (non)avoidance behaviour in invertebrates was studied in relation with the GABAergic system. We strongly recommend the combination of such gene and/or functional assay studies with the avoidance behaviour test as it can bring many advantages and important interpretation lines for ecotoxicity with minor effort.

  13. Prevalence, clinical, endoscopic and pathological features of duodenitis in children

    Science.gov (United States)

    Alper, Arik; Hardee, Steven; Rojas-velasquez, Danilo; Escalera, Sandra; Morotti, Raffaella A; Pashankar, Dinesh S.

    2015-01-01

    Objectives While gastritis and esophagitis are well studied in children, there is very limited literature on duodenitis in children. We aimed to assess the prevalence, etiology, clinical, endoscopic, and pathological features in a large cohort of unselected children with duodenitis. Methods We reviewed the pathology reports of all upper endoscopies performed at our institution over 5 years to identify children with duodenitis. Biopsy sections were reviewed to confirm the diagnosis of duodenitis. Demographic, clinical, endoscopic data and presence of associated gastritis and esophagitis were noted in all children with duodenitis. Etiology of duodenitis was correlated with the patient's clinical diagnosis. Results Out of 2772 children who had endoscopy, 352 had duodenitis with the prevalence rate of 12.7%. Gastritis was seen in 64% of children with duodenitis compared with 46% of children without duodenitis (P < 0.001). Common indications for endoscopy in children with duodenitis were abdominal pain, positive celiac serology and diarrhea. The most common etiology was celiac disease (32%), followed by Crohn's disease (13%), ulcerative colitis (3%), and Helicobacter pylori infection (6%). In 63% of cases, endoscopic appearance of duodenum was normal. Cryptitis, villous changes and cellular infiltration were noted on histology. Conclusions Prevalence of duodenitis is 12.7% in children undergoing endoscopy. Celiac disease and inflammatory bowel disease are common causes of duodenitis. Associated gastritis is common in children with duodenitis and correlation of endoscopic appearance with histology is poor. PMID:26252915

  14. Tangent Curve Function Description of Mechanical Behaviour of Bulk Oilseeds: A Review

    Directory of Open Access Journals (Sweden)

    Sigalingging R.

    2015-01-01

    Full Text Available The application of tangent curve mathematical model for description of mechanical behaviour of selected bulk oilseeds, namely jatropha, sunflower, rape, garden pea, and common bean in linear compression was reviewed. Based on the review analysis, the tangent curve function has been developed using MathCAD 14 software which employs the Levenberg-Marquardt algorithm for data fitting optimal for tangent curve approximation. Linear compression parameters including force (N, deformation (mm, energy (J, and/or volume energy (J-m-3 can equally be determined by the tangent model. Additionally, the theoretical dependency between force and deformation characteristic curves can be defined by the force coefficient of mechanical behaviour (N and deformation coefficient of mechanical behaviour (mm-1 of the tangent model. In conclusion, the review results, however, shows that the tangent curve mathematical model which is dependent on experimental boundary conditions is potentialy useful for theoretical description of mechanical properties and deformation characteristics of bulk oilseeds in axial compression.

  15. Influence of Water Content on the Mechanical Behaviour of Limestone: Role of the Clay Minerals Content

    Science.gov (United States)

    Cherblanc, F.; Berthonneau, J.; Bromblet, P.; Huon, V.

    2016-06-01

    The mechanical characteristics of various sedimentary stones significantly depend on the water content, where 70 % loss of their mechanical strengths can be observed when saturated by water. Furthermore, the clay fraction has been shown to be a key factor of their hydro-mechanical behaviour since it governs for instance the hydric dilation. This work aims at investigating the correlations between the clay mineral content and the mechanical weakening experienced by limestones when interacting with water. The experimental characterization focuses on five different limestones that exhibit very different micro-structures. For each of them, we present the determination of clay mineral composition, the sorption isotherm curve and the dependences of tensile and compressive strengths on the water content. It emerges from these results that, first, the sorption behaviour is mainly governed by the amount of smectite layers which exhibit the larger specific area and, second, the rate of mechanical strength loss depends linearly on the sorption capacity. Indeed, the clay fraction plays the role of a retardation factor that delays the appearance of capillary bridges as well as the mechanical weakening of stones. However, no correlation was evidenced between the clay content and the amplitude of weakening. Since the mechanisms whereby the strength decreases with water content are not clearly established, these results would help to discriminate between various hypothesis proposed in the literature.

  16. Research on the mechanical behaviour of an airplane component made by selective laser melting technology

    Directory of Open Access Journals (Sweden)

    Păcurar Răzvan

    2017-01-01

    Full Text Available The main objective of the presented research consists in the redesign of an airplane component to decrease its weight, without affecting the mechanical behaviour of the component, at the end. Femap NX Nastran and ANSYS FEA programs were used for the shape optimization and for the estimation of the mechanical behaviour of a fixing clamp that was used to sustain the hydraulic pipes that are passing through an airplane fuselage, taking into consideration two types of raw materials – Ti6Al4V and AlSi12 powder from which this component could be manufactured by using the selective laser melting (SLM technology. Based on the obtained results, the airplane component was finally manufactured from titanium alloy using the SLM 250 HL equipment that is available at SLM Solutions GmbH company from Luebeck, in Germany.

  17. Factors associated with gastro-duodenal disease in patients ...

    African Journals Online (AJOL)

    Factors associated with gastro-duodenal disease in patients undergoing ... recruit patients referred with upper gastro-intestinal symptoms for endoscopy. ... 64 had duodenal ulcer, 66 gastric ulcer, 27gastric cancer and 64 non-ulcer dyspepsia.

  18. Quantification of the passive and active biaxial mechanical behaviour and microstructural organization of rat thoracic ducts.

    Science.gov (United States)

    Caulk, Alexander W; Nepiyushchikh, Zhanna V; Shaw, Ryan; Dixon, J Brandon; Gleason, Rudolph L

    2015-07-06

    Mechanical loading conditions are likely to play a key role in passive and active (contractile) behaviour of lymphatic vessels. The development of a microstructurally motivated model of lymphatic tissue is necessary for quantification of mechanically mediated maladaptive remodelling in the lymphatic vasculature. Towards this end, we performed cylindrical biaxial testing of Sprague-Dawley rat thoracic ducts (n = 6) and constitutive modelling to characterize their mechanical behaviour. Spontaneous contraction was quantified at transmural pressures of 3, 6 and 9 cmH2O. Cyclic inflation in calcium-free saline was performed at fixed axial stretches between 1.30 and 1.60, while recording pressure, outer diameter and axial force. A microstructurally motivated four-fibre family constitutive model originally proposed by Holzapfel et al. (Holzapfel et al. 2000 J. Elast. 61, 1-48. (doi:10.1023/A:1010835316564)) was used to quantify the passive mechanical response, and the model of Rachev and Hayashi was used to quantify the active (contractile) mechanical response. The average error between data and theory was 8.9 ± 0.8% for passive data and 6.6 ± 2.6% and 6.8 ± 3.4% for the systolic and basal conditions, respectively, for active data. Multi-photon microscopy was performed to quantify vessel wall thickness (32.2 ± 1.60 µm) and elastin and collagen organization for three loading conditions. Elastin exhibited structural 'fibre families' oriented nearly circumferentially and axially. Sample-to-sample variation was observed in collagen fibre distributions, which were often non-axisymmetric, suggesting material asymmetry. In closure, this paper presents a microstructurally motivated model that accurately captures the biaxial active and passive mechanical behaviour in lymphatics and offers potential for future research to identify parameters contributing to mechanically mediated disease development. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  19. Numerical model for thermal and mechanical behaviour of a CANDU 37-element bundle

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, L.; MacKay, K. [Martec Limited, Halifax, Nova Scotia (Canada); Gibb, R. [Canadian Nuclear Safety Commission (CNSC), Ottawa, Ontario (Canada)

    2010-07-01

    Prediction of transient fuel bundle deformations is important for assessing the integrity of fuel and the surrounding structural components under different operating conditions including accidents. For numerical simulation of the interactions between fuel bundle and pressure tube, a reliable numerical bundle model is required to predict thermal and mechanical behaviour of the fuel bundle assembly under different thermal loading conditions. To ensure realistic representations of the bundle behaviour, this model must include all of the important thermal and mechanical features of the fuel bundle, such as temperature-dependent material properties, thermal viscoplastic deformation in sheath, fuel-to-sheath interactions, endplate constraints and contacts between fuel elements. In this paper, we present a finite element based numerical model for predicting macroscopic transient thermal-mechanical behaviour of a complete 37-element CANDU nuclear fuel bundle under accident conditions and demonstrate its potential for being used to investigate fuel bundle to pressure tube interaction in future nuclear safety analyses. This bundle model has been validated against available experimental and numerical solutions and applied to various simulations involving steady-state and transient loading conditions. (author)

  20. Westernblottinginthediagnosisof duodenal-biliary and pancreaticobiliary relfuxesinbiliarydiseases

    Institute of Scientific and Technical Information of China (English)

    Guo-Zhe Xian; Shuo-Dong Wu; Chun-Chih Chen; Yang Su

    2009-01-01

    BACKGROUND: Currently adopted diagnostic methods for duodenal-biliary and pancreaticobiliary relfuxes carry many lfaws, so the incidence of the two relfuxes demands further larger sample size studies. This study aimed to evaluate Western blotting for the diagnosis of relfuxes in biliary diseases. METHODS: An oral radionuclide 99mTc-DTPA test (radio-nuclide, RN) was conducted for the observation of duodenal-biliary relfux prior to measuring bile radioactivity and Western blotting for detecting bile enterokinase (EK). Pancreaticobiliary relfux was assessed by biochemical and Western blotting tests for biliary amylase activity and trypsin-1, respectively. In accordance with bile sample origin, our samples were classiifed into ductal bile and gall bile groups;based on each individual biliary disease, we further classiifed the ductal bile group into ifve sub-groups, and the gall bile group into four sub-groups. Western blotting was conducted to assess the two relfuxes in biliary diseases. RESULTS: Consistencies were noted between EK and RN tests when diagnosing duodenal-biliary relfux (P0.05); in the common bile duct cyst group, the EK positive rate was signiifcantly lower than the trypsin-1 positive rate (P CONCLUSIONS: Western blotting can accurately relfect duodenal-biliary and pancreaticobiliary relfuxes. EK has greater sensitivity than RN for duodenal-biliary relfux. The majority of biliary amylase and lipase comes from the pancreas in all biliary diseases;pancreaticobiliary relfux is the predominant source in the common bile duct cyst group and duodenal-biliary relfux is responsible for the ductal pigment stone group.

  1. Analysing hydro-mechanical behaviour of reinforced slopes through centrifuge modelling

    Science.gov (United States)

    Veenhof, Rick; Wu, Wei

    2017-04-01

    Every year, slope instability is causing casualties and damage to properties and the environment. The behaviour of slopes during and after these kind of events is complex and depends on meteorological conditions, slope geometry, hydro-mechanical soil properties, boundary conditions and the initial state of the soils. This study describes the effects of adding reinforcement, consisting of randomly distributed polyolefin monofilament fibres or Ryegrass (Lolium), on the behaviour of medium-fine sand in loose and medium dense conditions. Direct shear tests were performed on sand specimens with different void ratios, water content and fibre or root density, respectively. To simulate the stress state of real scale field situations, centrifuge model tests were conducted on sand specimens with different slope angles, thickness of the reinforced layer, fibre density, void ratio and water content. An increase in peak shear strength is observed in all reinforced cases. Centrifuge tests show that for slopes that are reinforced the period until failure is extended. The location of shear band formation and patch displacement behaviour indicate that the design of slope reinforcement has a significant effect on the failure behaviour. Future research will focus on the effect of plant water uptake on soil cohesion.

  2. Lubiprostone Stimulates Duodenal Bicarbonate Secretion in Rats

    OpenAIRE

    Mizumori, Misa; Akiba, Yasutada; Kaunitz, Jonathan D.

    2009-01-01

    Background Lubiprostone, a bicyclic fatty acid, is used for the treatment of chronic constipation. No published study has addressed the effect of lubiprostone on intestinal ion secretion in vivo. Aim The aim of this study was to test the hypothesis that lubiprostone augments duodenal HCO3 − secretion (DBS). Methods Rat proximal duodenal loops were perfused with pH 7.0 Krebs, control vehicle (medium-chain triglycerides), or lubiprostone (0.1–10 μM). We measured DBS with flow-through pH and CO2...

  3. Is duodenal biopsy appropriate in areas endemic for Helicobacter pylori?

    Science.gov (United States)

    Sahin, Abdurrahman; Cihangiroglu, Gulcin; Bilgic, Yilmaz; Calhan, Turan; Cengiz, Mustafa

    2017-01-01

    The primary reason for obtaining duodenal biopsy sample is to diagnose celiac disease. Helicobacter pylori (H. pylori) and drug injury are common causes of duodenitis. The aim of this retrospective study was to explore effects of H. pylori and drugs on duodenal mucosa. Duodenal biopsy samples of patients who underwent upper gastrointestinal endoscopy (UGIE) between February 2014 and December 2014 were retrospectively examined. Clinical symptoms, referral indications, endoscopic findings, H. pylori status, and drug history were recorded. Duodenal biopsy findings were compared based on presence of H. pylori and drug history. Of 2389 patients who underwent UGIE, 206 had duodenal biopsy. Eight patients (3.9%) were diagnosed with celiac disease. After excluding cases with celiac disease, 76 patients of remaining 198 patients (36.9%) had duodenal histopathological abnormality. H. pylori was found in 95 (47.9%) patients. Drug usage was less common (42%). Of patients who had histopathological duodenitis, 59% were H. pylori-infected. Rate of duodenitis was higher in H. pylori (+) group than in H. pylori (-) group (45% vs 27.1%; odds ratio, 2.4; 95% confidence interval, 1.3-4.4; p=0.005). There was no difference between groups regarding drug use in terms of histopathological duodenitis. H. pylori is the major contributor to duodenitis in high prevalence regions. Serological testing may be more appropriate before performing duodenal biopsy in patients with suspected celiac disease.

  4. MECHANICAL BEHAVIOUR OF MAIN FLOOR FOR WATER INRUSH IN LONGWALL MINING

    Institute of Scientific and Technical Information of China (English)

    钱鸣高; 缪协兴; 黎良杰

    1995-01-01

    In this paper a new mechanical model indicating the mechanical behaviour of main floor in longwall mining is proposed. In the model the unfractured main floor is considerel as an elastoplastic plate, and the combination of fractured blocks as a voussoir beam. Using the plastic limit theory of plates, the limit load acting on main floor and the position of its largest deformation are gotten. The stability conditions for the key blocks of the voussoir beam are analysed by “S-R” stability theory. The results of the theoretical analysis are important for the study on the water inrush from seam floor.

  5. Fracture mechanics behaviour of ductile cast iron and martensitic steel at elevated temperature

    Energy Technology Data Exchange (ETDEWEB)

    Udoh, A.; Klenk, A.; Roos, E. [Stuttgart Univ. (Germany). MPA; Sasikala, G. [Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam (India)

    2010-07-01

    Ductile cast iron is employed increasingly due to the advantages regarding foundry practice, design as well as economic advantages in the thermal machinery and power plant construction. It is employed preferably where higher toughness is required, e.g. in valves or thickwalled components of thermal or nuclear power plants. For this reason the safety and availability criteria for fracture mechanics assessment of components are necessary in addition to the conventional strength design. Alloys with silicon and molybdenum are developed for the application at higher temperatures. The increase in the thermal efficiency of fossil fired steam power plant that can be achieved by increasing the steam temperature and pressure has provided the incentive for development of the 9% chromium steels towards improved creep rupture strength. During the last twenty years, three such steels, P91 (9Cr-1Mo-VNb), E911 (9Cr-1Mo-1W-V-Nb) and P92 (9Cr-0,5Mo-1,8W-V-Nb), have been developed for commercial production. For application in piping systems and boiler construction sufficient reliable information concerning the long-term behaviour are necessary as well as knowledge about fracture mechanical behaviour in order to ensure integrity of components. Different methods to characterize fracture behaviour of ductile cast iron and martensitic steel at elevated temperature have been employed. The RBR method is a novel and simple method developed at IGCAR for characterizing the ductile fracture behaviour of materials from tensile tests of cylindrical specimens. Using the data evaluated at both institutes, a fracture mechanics characterisation by determining crack initiation and crack resistance by J{sub R}-curves and RBR parameters is presented. (orig.)

  6. Nanoscale grain growth behaviour of CoAl intermetallic synthesized by mechanical alloying

    Indian Academy of Sciences (India)

    S N Hosseini; M H Enayati; F Karimzadeh

    2014-05-01

    Grain growth behaviour of the nanocrystalline CoAl intermetallic compound synthesized by mechanical alloying has been studied by isothermal annealing at different temperatures and durations. X-ray diffraction method was employed to investigate structural evolutions during mechanical alloying and annealing processes. The disordered CoAl phase with the grain size of about 6 nm was formed via a gradual reaction during mechanical alloying. The results of isothermal annealing showed that the grain growth behaviour can be explained by the parabolic grain growth law. The grains were at nanometric scale after isothermal annealing up to 0.7 m. The grain growth exponent remained constant above 873 K indicating that grain growth mechanism does not change at high temperatures. The calculated activation energy indicated that the grain growth mechanism in the disordered CoAl phase at high temperatures was diffusing Co and Al atoms in two separate sublattices. Furthermore, an equation has been suggested to describe the grain growth kinetics of nanocrystalline CoAl under isothermal annealing at temperatures above 873 K (/m ≥ 0.5).

  7. Empathy as a driver of prosocial behaviour: highly conserved neurobehavioural mechanisms across species.

    Science.gov (United States)

    Decety, Jean; Bartal, Inbal Ben-Ami; Uzefovsky, Florina; Knafo-Noam, Ariel

    2016-01-19

    Empathy reflects the natural ability to perceive and be sensitive to the emotional states of others, coupled with a motivation to care for their well-being. It has evolved in the context of parental care for offspring, as well as within kinship bonds, to help facilitate group living. In this paper, we integrate the perspectives of evolution, animal behaviour, developmental psychology, and social and clinical neuroscience to elucidate our understanding of the proximate mechanisms underlying empathy. We focus, in particular, on processing of signals of distress and need, and their relation to prosocial behaviour. The ability to empathize, both in animals and humans, mediates prosocial behaviour when sensitivity to others' distress is paired with a drive towards their welfare. Disruption or atypical development of the neural circuits that process distress cues and integrate them with decision value leads to callous disregard for others, as is the case in psychopathy. The realization that basic forms of empathy exist in non-human animals is crucial for gaining new insights into the underlying neurobiological and genetic mechanisms of empathy, enabling translation towards therapeutic and pharmacological interventions.

  8. Empathy as a driver of prosocial behaviour: highly conserved neurobehavioural mechanisms across species

    Science.gov (United States)

    Decety, Jean; Bartal, Inbal Ben-Ami; Uzefovsky, Florina; Knafo-Noam, Ariel

    2016-01-01

    Empathy reflects the natural ability to perceive and be sensitive to the emotional states of others, coupled with a motivation to care for their well-being. It has evolved in the context of parental care for offspring, as well as within kinship bonds, to help facilitate group living. In this paper, we integrate the perspectives of evolution, animal behaviour, developmental psychology, and social and clinical neuroscience to elucidate our understanding of the proximate mechanisms underlying empathy. We focus, in particular, on processing of signals of distress and need, and their relation to prosocial behaviour. The ability to empathize, both in animals and humans, mediates prosocial behaviour when sensitivity to others' distress is paired with a drive towards their welfare. Disruption or atypical development of the neural circuits that process distress cues and integrate them with decision value leads to callous disregard for others, as is the case in psychopathy. The realization that basic forms of empathy exist in non-human animals is crucial for gaining new insights into the underlying neurobiological and genetic mechanisms of empathy, enabling translation towards therapeutic and pharmacological interventions. PMID:26644596

  9. Predicting Chemically Induced Duodenal Ulcer and Adrenal Necrosis with Classification Trees

    Science.gov (United States)

    Giampaolo, Casimiro; Gray, Andrew T.; Olshen, Richard A.; Szabo, Sandor

    1991-07-01

    Binary tree-structured statistical classification algorithms and properties of 56 model alkyl nucleophiles were brought to bear on two problems of experimental pharmacology and toxicology. Each rat of a learning sample of 745 was administered one compound and autopsied to determine the presence of duodenal ulcer or adrenal hemorrhagic necrosis. The cited statistical classification schemes were then applied to these outcomes and 67 features of the compounds to ascertain those characteristics that are associated with biologic activity. For predicting duodenal ulceration, dipole moment, melting point, and solubility in octanol are particularly important, while for predicting adrenal necrosis, important features include the number of sulfhydryl groups and double bonds. These methods may constitute inexpensive but powerful ways to screen untested compounds for possible organ-specific toxicity. Mechanisms for the etiology and pathogenesis of the duodenal and adrenal lesions are suggested, as are additional avenues for drug design.

  10. Cytomegalovirus duodenitis associated with life-threatening duodenal hemorrhage in an immunocompetent patient: A case report

    Directory of Open Access Journals (Sweden)

    Lucy Shen

    2017-01-01

    Conclusion: Presented is a rare case of life-threatening GI hemorrhage caused by CMV duodenitis in an immunocompetent patient. The patient failed endoscopic and interventional-radiology treatment options, and ultimately stabilized after surgical intervention.

  11. Duodenal obstruction following acute pancreatitis caused by a large duodenal diverticular bezoar

    Institute of Scientific and Technical Information of China (English)

    Ji Hun Kim; Jae Hyuck Chang; Sung Min Nam; Mi Jeong Lee; Il Ho Maeng; Jin Young Park; Yun Sun Im

    2012-01-01

    Bezoars are concretions of indigestible materials in the gastrointestinal tract.It generally develops in patients with previous gastric surgery or patients with delayed gastric emptying.Cases of periampullary duodenal divericular bezoar are rare.Clinical manifestations by a bezoar vary from no symptom to acute abdominal syndrome depending on the location of the bezoar.Biliary obstruction or acute pancreatitis caused by a bezoar has been rarely reported.Small bowel obstruction by a bezoar is also rare,but it is a complication that requires surgery.This is a case of acute pancreatitis and subsequent duodenal obstruction caused by a large duodenal bezoar migrating from a periampullary diverticulum to the duodenal lumen,which mimicked pancreatic abscess or microperforation on abdominal computerized tomography.The patient underwent surgical removal of the bezoar and recovered completely.

  12. Mechanical, thermal, rheological and morphological behaviour of irradiated PP/HA composites

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, C. [Universidad de Oriente, Nucleo de Anzoategui, Escuela de Ingenieria y Ciencias Aplicadas, Depto de Ingenieria Quimica, Puerto la Cruz (Venezuela); Albano, C. [Centro de Quimica, Laboratorio de Polimeros, Instituto Venezolano de Investigaciones Cientificas (IVIC), Caracas 1020A (Venezuela) and Universidad Central de Venezuela, Facultad de Ingenieria, Escuela de Ingenieria Quimica, Caracas 1041A (Venezuela)]. E-mail: calbano@ivic.ve; Karam, A. [Centro de Quimica, Laboratorio de Polimeros, Instituto Venezolano de Investigaciones Cientificas (IVIC), Caracas 1020A (Venezuela)]. E-mail: akaram@quimica.ivic.ve; Dominguez, N. [Centro de Quimica, Laboratorio de Polimeros, Instituto Venezolano de Investigaciones Cientificas (IVIC), Caracas 1020A (Venezuela); Sanchez, Y. [Centro de Quimica, Laboratorio de Polimeros, Instituto Venezolano de Investigaciones Cientificas (IVIC), Caracas 1020A (Venezuela); Gonzalez, G. [Centro Tecnologico, Instituto Venezolano de Investigaciones Cientificas (IVIC), Caracas 1020A (Venezuela)

    2005-07-01

    Hydroxyapatite (HA) reinforced polypropylene (PP) composites are being developed as bone graft materials. In this research, the effect of {gamma} irradiation on mechanical, rheological, thermal and morphological behaviour of PP-HA composites was studied. The melt flow index of polymer increased markedly when it was exposed to radiation. This is indicative of chain scission reaction as the predominant process. During the tensile testing, the composites exhibited brittle behaviour, showing no fluency point. Elongation at break showed a tendency to decrease with the increase in radiation dose while stress at break did not show significant variation with radiation dose. High HA content (>20%) and radiation dose (25 kGy) had significant influence on thermal stability.

  13. Mechanical and thermal behaviour of U-Mo and U-Nb-Zr Alloys

    Science.gov (United States)

    Lopes, Denise Adorno; Guisard Restivo, Thomaz Augusto; Padilha, Angelo Fernando

    2013-09-01

    Nuclear fuels composed of uranium alloys in monolithic and dispersed forms are being considered for research and compact power reactors due to their density properties (greater than 15 g-U/cm3) and fast heat transfer. U-Nb-Zr and U-Mo alloys are the most promising systems for plate fuel elements owing to their broad γ-phase stability field, which shows higher ductility and isotropic behaviour, allowing extensive fabrication capability. In the present work, γ-phase stabilized U-7.5Nb-2.5Zr and U-10Mo alloys were characterized by mechanical and thermal analyses for comparison of their behaviour under deformation and heat-treatment. The results demonstrate that the alloys have substantially different properties regarding deformation, kinetics phase transformation and recovery/recrystallization. The main results show that U-Nb-Zr is superior regarding fabrication capabilities although the γ-phase is less stable than U-Mo alloys.

  14. Mechanical Properties and Water Absorption Behaviour of Durian Rind Cellulose Reinforced Poly(lactic acid Biocomposites

    Directory of Open Access Journals (Sweden)

    Patpen Penjumras

    2015-01-01

    Full Text Available Environmental concerns have resulted in replacing petrochemically derived polymer with biodegradable renewable resource. In this study, mechanical properties and water absorption behaviour of durian rind cellulose reinforced poly(lactic acid biocomposites were investigated. Poly(lactic acid was mixed with 25 and 35 wt. % of durian rind cellulose that was derived from durian consumption wastes. The biocomposties were melt-blended at 165 and 175 °C with 15 min using a Brabender internal mixer followed by a hot compression moulding technique. The results showed that impact strength and modulus of Young increased with increasing of cellulose content but decreased at higher mixing temperature. Water absorption behaviour of biocomposites as function of days was also investigated. It was found that the water absorption amount of biocomposites increased with increasing of cellulose content and exposure time.    

  15. Mechanical and thermal behaviour of U–Mo and U–Nb–Zr Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Denise Adorno [LABMAT, Centro Tecnológico da Marinha em São Paulo, Rod. Sorocaba-Iperó km 12.5, 18560-000 Iperó, SP (Brazil); Guisard Restivo, Thomaz Augusto, E-mail: guisard@dglnet.com.br [UNISO, Universidade de Sorocaba, Rod. Raposo Tavares km 92.5, 18023-000 Sorocaba, SP (Brazil); Escola Politécnica USP, Av. Prof. Mello Moraes, 2463 05508-030 São Paulo, SP (Brazil); Padilha, Angelo Fernando [Escola Politécnica USP, Av. Prof. Mello Moraes, 2463 05508-030 São Paulo, SP (Brazil)

    2013-09-15

    Nuclear fuels composed of uranium alloys in monolithic and dispersed forms are being considered for research and compact power reactors due to their density properties (greater than 15 g-U/cm{sup 3}) and fast heat transfer. U–Nb–Zr and U–Mo alloys are the most promising systems for plate fuel elements owing to their broad γ-phase stability field, which shows higher ductility and isotropic behaviour, allowing extensive fabrication capability. In the present work, γ-phase stabilized U–7.5Nb–2.5Zr and U–10Mo alloys were characterized by mechanical and thermal analyses for comparison of their behaviour under deformation and heat-treatment. The results demonstrate that the alloys have substantially different properties regarding deformation, kinetics phase transformation and recovery/recrystallization. The main results show that U–Nb–Zr is superior regarding fabrication capabilities although the γ-phase is less stable than U–Mo alloys.

  16. The complicated duodenal diverticulum: retrospective analysis of 11 cases.

    Science.gov (United States)

    de Perrot, Thomas; Poletti, Pierre-Alexandre; Becker, Christoph D; Platon, Alexandra

    2012-01-01

    A series of rare complicated duodenal diverticula were reported with emphasis on causes for misdiagnosis. Patients with a discharge diagnosis of complicated duodenal diverticulum were retrospectively obtained. Computed tomographic (CT) reports and findings were reviewed. Complications consisted of diverticulitis (n=2), perforation (n=7), or obstructive cholangitis (n=2). CT imaging demonstrated a duodenal diverticular structure with findings due to the kind of complications. At the time of CT interpretation, a complicated duodenal diverticulum was suspected in 5 out of 11 patients. Awareness of the duodenal diverticulum and complications may improve the diagnostic value of CT in this setting. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Duodenal organ injury severity (OIS) and outcome.

    Science.gov (United States)

    Kline, G; Lucas, C E; Ledgerwood, A M; Saxe, J M

    1994-07-01

    The effect of organ injury severity on outcome was assessed in 101 patients treated for duodenal trauma. Most patients were men (89%) and victims of penetrating wounds (93%). Grade I is minor hematoma or incomplete perforation; Grade II is major hematoma or small complete perforation; Grade III is large perforation excluding ampulla; Grade IV is large perforation at ampulla; Grade V is duodenopancreatic crunch. The injuries were as follows: Grade I (5 patients), Grade II (31), Grade III (40), Grade IV (12), and Grade V (13). Fourteen patients exsanguinated from associated vessel injury; each had Grade IV or Grade V injury. All 36 patients with Grade I and Grade II injury had primary repair; the single death was due to liver necrosis. Most (31 patients) Grade III injuries and three Grade IV injuries were treated by primary repair alone; the three deaths were unrelated to the duodenal injury. Other major injuries were treated by duodenal exclusion (4 patients), duodenal diverticulization (6), or resection (4); the single death was unrelated to the duodenum. Primary closure is favored for minor injuries and most Grade III injuries. Severe injuries may require exclusion, diverticulization, or resection.

  18. Duodenal Amyloidosis Masquerading as Iron Deficiency Anemia

    Science.gov (United States)

    Hurairah, Abu

    2016-01-01

    The present study is a unique illustration of duodenal amyloidosis initially manifesting with iron deficiency anemia. It underscores the importance of clinical suspicion of amyloidosis while performing upper gastrointestinal endoscopy with a biopsy to establish the definite diagnosis in patients with unexplained iron deficiency anemia. PMID:27625911

  19. Endoscopic biopsy: Duodenal ulcer penetrating into liver

    Institute of Scientific and Technical Information of China (English)

    Baybora Kircali; Tülay Saricam; Aysegul Ozakyol; Eser Vardareli

    2005-01-01

    @@ TO THE EDITOR We have read with interest the recent report by E Kayacetin and S Kayacetin of Gastric ulcer penetrating to liver diagnosed by endoscopic biopsy[1] since we diagnosed the duodenal ulcer which penetrated into liver similarly. This is a rather unusual case because of the fifth case in the literature and responding to medical therapy.

  20. Adult duodenal intussusception associated with congenital malrotation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Enteroenteric intussusception is a condition in which full-thickness bowel wall becomes telescoped into the lumen of distal bowel. In adults, there is usually an abnormality acting as a lead point, usually a Meckels' diverticulum, a hamartoma or a tumour. Duodenoduodenal intussusception is exceptionally rare because the retroperitoneal situation fixes the duodenal wall.The aim of this report is to describe the first published case of this condition. A patient with duodeno-duodenal intussusception secondary to an ampullary lesion is reported. A 66 year-old lady presented with intermittent abdominal pain, weight loss and anaemia. Ultrasound scanning showed dilated bile and pancreatic ducts.CT scanning revealed intussusception involving the full-thickness duodenal wall. The lead point was an ampullary villous adenoma. Congenital partial (type Ⅱ)malrotation was found at operation and this abnormality permitted excessive mobility of the duodenal wall such that intussusception was possible. This condition can be diagnosed using enhanced CT. Intussusception can be complicated by bowel obstruction, ischaemia or bleeding,and therefore the underlying cause should be treated as soon as possible.

  1. Effects of suspension-induced osteopenia on the mechanical behaviour of mouse long bones

    Science.gov (United States)

    Simske, S. J.; Greenberg, A. R.; Luttges, M. W.; Spooner, B. S. (Principal Investigator)

    1991-01-01

    Whereas most studies of tail-suspension induced osteopenia have utilized rat femora, the present study investigated the effects of a 14 day tail-suspension on the mechanical behaviour of mice femora, tibiae and humeri. Force-deflection properties were obtained via three-point bending for long bones from suspended and control mice. Whole bone behaviour was characterized by converting the force-deflection values to stiffness, strength, ductility and energy parameters which were not normalized for specimen geometry. The effects of a systematic variation in the deflection rate over the range 0.1-10 mm min-1 were also evaluated. Statistical analysis indicated that the primary effect of the tail-suspension period was lowered bone mass which was manifested mechanically through lower values of the bone strength parameters. These effects were similar in the bones of both the fore and hind limbs. The results also demonstrated that the stiffness, ductility and energy characteristics were much less influenced by the tail-suspension. Whereas a significant dependence of the bone strength values upon deflection rate was observed for the femora and humeri, the other mechanical parameters were less sensitive. Based upon the nature of the physical and mechanical changes observed in the long bones following tail-suspension, the mouse appears to be a suitable animal model for the study of osteopenia.

  2. Mechanical behaviour of PEM fuel cell catalyst layers during regular cell operation

    Directory of Open Access Journals (Sweden)

    Maher A.R. Sadiq Al-Baghdadi

    2010-11-01

    Full Text Available Damage mechanisms in a proton exchange membrane fuel cell are accelerated by mechanical stresses arising during fuel cell assembly (bolt assembling, and the stresses arise during fuel cell running, because it consists of the materials with different thermal expansion and swelling coefficients. Therefore, in order to acquire a complete understanding of the mechanical behaviour of the catalyst layers during regular cell operation, mechanical response under steady-state hygro-thermal stresses should be studied under real cell operating conditions and in real cell geometry (three-dimensional. In this work, full three-dimensional, non-isothermal computational fluid dynamics model of a PEM fuel cell has been developed to investigate the behaviour of the cathode and anode catalyst layers during the cell operation. A unique feature of the present model is to incorporate the effect of hygro and thermal stresses into actual three-dimensional fuel cell model. In addition, the temperature and humidity dependent material properties are utilize in the simulation for the membrane. The model is shown to be able to understand the many interacting, complex electrochemical, transport phenomena, and deformation that have limited experimental data.

  3. Wear Resistance and Mechanical Behaviour of Epoxy/Mollusk Shell Biocomposites developed for Structural Applications

    Directory of Open Access Journals (Sweden)

    I.O. Oladele

    2016-09-01

    Full Text Available Epoxy resin is one of the strongest commercially exploitable thermosetting polymers in the polymer family; however its expensive nature in comparison with other thermosetting polymers such as vinylester and polyester limits its applications as a structural material. Inexpensive fillers on the other hand, especially those derived from agro-industrial wastes are very important in reducing the overall cost of polymer composites and furthermore influential in enhancing some of their engineering properties. In the present study, the wear resistance and mechanical behaviour of epoxy polymer matrix filled with <75 and 75 μm calcined particles of African land snail shells have been comparatively investigated. The wear resistance and the mechanical behaviour of the composites were studied via Taber Abraser and INSTRON universal testing machine. Also, the elemental constituents of the calcined snail shell and the epoxy biocomposites were characterized by X-Ray Fluorescence Spectroscopy and Scanning Electron Microscopy/Energy Dispersion Spectroscopy. From the experimental results, it was observed that, at the highest filler loading, smaller particle size presented a biocomposite with significant enhancement in wear and mechanical properties. However, it was also observed that increase in particle size showed no significant enhancement in the mechanical properties of the biocomposites.

  4. Influence of temperature on patch residence time in parasitoids: physiological and behavioural mechanisms.

    Science.gov (United States)

    Moiroux, Joffrey; Abram, Paul K; Louâpre, Philippe; Barrette, Maryse; Brodeur, Jacques; Boivin, Guy

    2016-04-01

    Patch time allocation has received much attention in the context of optimal foraging theory, including the effect of environmental variables. We investigated the direct role of temperature on patch time allocation by parasitoids through physiological and behavioural mechanisms and its indirect role via changes in sex allocation and behavioural defences of the hosts. We compared the influence of foraging temperature on patch residence time between an egg parasitoid, Trichogramma euproctidis, and an aphid parasitoid, Aphidius ervi. The latter attacks hosts that are able to actively defend themselves, and may thus indirectly influence patch time allocation of the parasitoid. Patch residence time decreased with an increase in temperature in both species. The increased activity levels with warming, as evidenced by the increase in walking speed, partially explained these variations, but other mechanisms were involved. In T. euproctidis, the ability to externally discriminate parasitised hosts decreased at low temperature, resulting in a longer patch residence time. Changes in sex allocation with temperature did not explain changes in patch time allocation in this species. For A. ervi, we observed that aphids frequently escaped at intermediate temperature and defended themselves aggressively at high temperature, but displayed few defence mechanisms at low temperature. These defensive behaviours resulted in a decreased patch residence time for the parasitoid and partly explained the fact that A. ervi remained for a shorter time at the intermediate and high temperatures than at the lowest temperature. Our results suggest that global warming may affect host-parasitoid interactions through complex mechanisms including both direct and indirect effects on parasitoid patch time allocation.

  5. Mechanical and Corrosion Behaviour of Zn-27Al Based Composites Reinforced with Groundnut Shell Ash and Silicon Carbide

    OpenAIRE

    K.K. Alaneme; B.O. Fatile; J.O. Borode

    2014-01-01

    The mechanical and corrosion behaviour of Zn-27Al alloy based composites reinforced with groundnut shell ash and silicon carbide was investigated. Experimental test composite samples were prepared by melting Zn-27Al alloy with pre-determined proportions of groundnut ash and silicon carbide as reinforcements using double stir casting. Microstructural examination, mechanical properties and corrosion behaviour were used to characterize the composites produced. The results show that hardness and ...

  6. A cell-based computational model of early embryogenesis coupling mechanical behaviour and gene regulation

    Science.gov (United States)

    Delile, Julien; Herrmann, Matthieu; Peyriéras, Nadine; Doursat, René

    2017-01-01

    The study of multicellular development is grounded in two complementary domains: cell biomechanics, which examines how physical forces shape the embryo, and genetic regulation and molecular signalling, which concern how cells determine their states and behaviours. Integrating both sides into a unified framework is crucial to fully understand the self-organized dynamics of morphogenesis. Here we introduce MecaGen, an integrative modelling platform enabling the hypothesis-driven simulation of these dual processes via the coupling between mechanical and chemical variables. Our approach relies upon a minimal ‘cell behaviour ontology' comprising mesenchymal and epithelial cells and their associated behaviours. MecaGen enables the specification and control of complex collective movements in 3D space through a biologically relevant gene regulatory network and parameter space exploration. Three case studies investigating pattern formation, epithelial differentiation and tissue tectonics in zebrafish early embryogenesis, the latter with quantitative comparison to live imaging data, demonstrate the validity and usefulness of our framework. PMID:28112150

  7. Mechanical and wear behaviour of steel chips reinforced Zn27Al composites

    Directory of Open Access Journals (Sweden)

    Kenneth Kanayo ALANEME

    2016-12-01

    Full Text Available The mechanical and wear behaviour of Zn27Al alloy reinforced with steel machining chips (an industrial waste was investigated. Two step stir casting process was used to produce the Zn27Al based composites consisting of 5, 7.5 and 10 wt.% of the steel machining chips while unreinforced Zn27Al alloy and a composition consisting of 5 wt.% alumina were also prepared as control samples. Microstrutural analysis; mechanical and wear behaviour were assessed for these composites. The results show that the hardness and wear resistance of the composites increased with increase in weight percent of the steel chips from 5 to 10 wt.%. The UTS, strain to fracture, and the fracture toughness were however highest for the 5 wt.% steel chips reinforced composite grade; and decreased with increase in the weight percent of the steel chips from 5 to 10 wt.%. Generally the Zn27Al alloy based composites reinforced with steel machining chips, exhibited superior mechanical and wear properties in comparison to the unreinforced Zn27Al alloy and the 5 wt.% alumina reinforced Zn27Al alloy composite.

  8. A comparative study of the effects of constructional elements on the mechanical behaviour of dragonfly wings

    Science.gov (United States)

    Rajabi, H.; Rezasefat, M.; Darvizeh, A.; Dirks, J.-H.; Eshghi, Sh.; Shafiei, A.; Mostofi, T. Mirzababaie; Gorb, S. N.

    2016-01-01

    Although wings of insects show a large variation in morphology, they are all made from a network of irregular veins interconnected through membranous areas. Depending on their shape, size, and position, wing veins are usually divided into three different groups: longitudinal veins, cross-veins and ambient veins. The veins together with the membrane and some other elements such as spines, nodus and pterostigma can be considered as the wing's "constructional elements". In spite of rather extensive literature on dragonfly wing structure, the role of each of these elements in determining the wing's function remains mostly unknown. As this question is difficult to answer in vivo using biomechanical experiments on actual wings, this study was undertaken to reveal the effects of the constructional elements on the mechanical behaviour of dragonfly wings by applying numerical simulations. An image processing technique was used to develop 12 finite element models of the insect wings with different constructional elements. The mechanical behaviour of these models was then simulated under normal and shear stresses due to tension, bending and torsion. A free vibration analysis was also performed to determine the resonant frequencies and the mode shapes of the models. For the first time, a quantitative comparison was carried out between the mechanical effects selectively caused by different elements. Our results suggest that the complex interactions of veins, membranes and corrugations may considerably affect the dynamic deformation of the insect wings during flight.

  9. Order information coding in working memory: Review of behavioural studies and cognitive mechanisms

    Directory of Open Access Journals (Sweden)

    Barbara Dolenc

    2014-06-01

    Full Text Available Executive processes, such as coding for sequential order, are of extreme importance for higher-order cognitive tasks. One of the significant questions is, how order information is coded in working memory and what cognitive mechanisms and processes mediate it. The aim of this review paper is to summarize results of studies that explore whether order and item memory are two separable processes. Furthermore, we reviewed evidence for each of the proposed cognitive mechanism that might mediate order processing. Previous behavioural and neuroimaging data suggest different representation and processing of item and order information in working memory. Both information are maintained and recalled separately and this separation seems to hold for recognition as well as for recall. To explain the result of studies of order coding, numerous cognitive mechanisms were proposed. We focused on four different mechanisms by which order information might be coded and retrieved, namely inter-item associations, direct coding, hierarchical coding and magnitude coding. Each of the mechanisms can explain some of the aspect of order information coding, however none of them is able to explain all of the empirical findings. Due to its complex nature it is not surprising that a single mechanism has difficulties accounting for all the behavioral data and order memory may be more accurately characterized as the result of a set of mechanisms rather than a single one. Moreover, the findings beget a question of whether different types of memory for order information might exist.

  10. Duodenal Bulb Mucosa with Hypertrophic Gastric Oxyntic Heterotopia in Patients with Zollinger Ellison Syndrome

    Directory of Open Access Journals (Sweden)

    Emil Kohan

    2009-01-01

    Full Text Available Objectives. Zollinger-Ellison Syndrome (ZES results in hypersecretion of gastric acid (via gastrinoma leading to peptic ulcers, diarrhea, and abdominal pain. We describe the novel discovery of hypertrophic, heterotopic gastric mucosa in the proximal duodenal bulb in patients with ZES, which we hypothesize results in an increased incidence of postbulbar ulcers in patients with ZES (a mechanism previously unreported. We determined the incidence of the novel finding of duodenal gastric oxyntic hypertrophic heterotopia (GOH in patients with ZES. Methods. Seven patients with ZES were enrolled. The diagnosis of ZES was established by hypergastrinemia, gastric acid hypersecretion, and a positive secretin test or based on biopsy specimens (evaluated via tissue staining. Basal acid output (BAO and baseline gastrin secretion were determined by established methods. Endoscopic examinations with methylene blue staining and biopsy of the gastric and duodenal mucosa were conducted in all patients every 3–6 months for an average of 5 years. Results. The duodenal mucosa demonstrated hypertrophic GOH in 5 out of 7 patients with ZES and an intact stomach and duodenum. Biopsies from the bowel mucosa demonstrated patchy replacement of surface epithelium by gastric-type epithelium with hypertrophic oxyntic glands in the lamina propria in 5 patients. Two of the patients had no evidence of GOH in the duodenal bulb. Patients with GOH had an average serum gastrin level of 1245 pg/mL and BAO of 2.92 mEq/hr versus 724 pg/mL and 0.8 mEq/hr in patients without GOH. Conclusions. This study demonstrated the presence of duodenal mucosa with GOH in 5 out of 7 patients with ZES and an intact stomach and duodenum. The presence of hypertrophic and heterotopic gastric mucosa is proposed to result from increased gastrin levels and may contribute to the increased incidence of postbulbar ulcers in these patients.

  11. Neonatal Duodenal Obstruction: A 15-Year Experience

    Directory of Open Access Journals (Sweden)

    Kamal Nain Rattan

    2016-04-01

    Full Text Available Background: Congenital duodenal obstruction is one of the commonest causes of neonatal intestinal obstruction. We are presenting our 15-year experience by analyzing clinical spectrum and outcome in neonates with duodenal obstruction admitted at our center. Material and Methods: The hospital records of all neonates admitted with duodenal obstruction from June 2000 to June 2015 were reviewed. The patient records were analyzed for antenatal diagnosis, age, sex, clinical presentation, diagnosis, associated anomalies, surgical procedures performed; postoperative morbidity and mortality. We excluded from our study malrotation of gut associated with congenital diaphragmatic hernia and abdominal wall defects. Results: A total of 81 patients were admitted, out of which 56 were males and 25 were females. Polyhydramnios was detected in 24 (30% pregnancies. Average birth weight was 2.1±1.0Kg and average gestational age was 38 (SD±1 weeks with 17 (21% preterm neonates. Presenting features were vomiting in 81(100% which was bilious in 81% and non bilious in 19%, epigastric fullness in 56 (69% and dehydration in 18 (22% and failure to thrive in 16 (19%. Most common cause of obstruction was duodenal atresia in 38 (46.9%, followed by malrotation of gut in 33 (40.7%, and annular pancreas in 4 cases. Depending upon site of location, infra-ampullary obstruction was the most common in 64 (79%, supra-ampullary in 9 (7.4% and ampullary 8 neonates. Both duodenal atresia and malrotation of gut was present in 4 cases. X-ray abdomen was most commonly used investigation to confirm the diagnosis. All cases were managed surgically by open laparotomy. Eleven (13.5% patients died due to sepsis and associated congenital anomalies. Conclusion: Congenital duodenal obstruction most commonly presents in early neonatal period with features of upper GIT obstruction like vomiting and epigastrium fullness as in our series. Early antenatal diagnosis and surgical interventions hold the

  12. A numerical study on the mechanical properties and the processing behaviour of composite high strength steels

    Energy Technology Data Exchange (ETDEWEB)

    Muenstermann, Sebastian [RWTH Aachen (Germany). Dept. of Ferrous Metallurgy; Vajragupta, Napat [RWTH Aachen (Germany). Materials Mechanics Group; Weisgerber, Bernadette [ThyssenKrupp Steel Europe AG (Germany). Patent Dept.; Kern, Andreas [ThyssenKrupp Steel Europe AG (Germany). Dept. of Quality Affairs

    2013-06-01

    The demand for lightweight construction in mechanical and civil engineering has strongly promoted the development of high strength steels with excellent damage tolerance. Nowadays, the requirements from mechanical and civil engineering are even more challenging, as gradients in mechanical properties are demanded increasingly often for components that are utilized close to the limit state of load bearing capacity. A metallurgical solution to this demand is given by composite rolling processes. In this process components with different chemical compositions were jointed, which develop after heat treatment special properties. These are actually evaluated in order to verify that structural steels with the desired gradients in mechanical properties can be processed. A numerical study was performed aiming to numerically predict strenght and toughness properties, as well as the procesing behaviour using Finite Element (FE) simulations with damage mechanics approaches. For determination of mechanical properties, simulations of tensile specimen, SENB sample, and a mobile crane have been carried out for different configurations of composite rolled materias out of high strebght structural steels. As a parameter study, both the geometrical and the metallurgical configurations of the composite rolled steels were modified. Thickness of each steel layer and materials configuration have been varied. Like this, a numerical procedure to define optimum tailored configurations of high strenght steels could be established.

  13. Evolutionary Psychology: How Psychological Mechanisms Shaped by Natural Selection for Ancestral Environments Produce Current Behaviours

    Institute of Scientific and Technical Information of China (English)

    Charles Crawford

    2009-01-01

    The central purpose of this paper is to explain how Darwin's theory of evolution by natural selection can be used in understanding current human behaviour. First, Darwin's logic is briefly described. Development is an important issue when applying evolutionary theory to human behaviour. The notion of innate developmental orga-nization of psychological mechanisms is introduced. The possible social and political outcomes produced when differ-ent levels of innate developmental organization are paired with different beliefs about it are considered. The notion of psychological mechanisms as evolved adaptations is considered in some detail. Then I discuss different ways evo-htionists think about how genes are involved in the development of adaptations. The paper concludes with a frame-work for considering how ancestral adaptations function in current environments and outlines some ways of studying them. In China and many other parts of the world people desire a more harmonious society. Ⅰ hope that this paper will be of some small help in achieving this great task.

  14. A new experimental setup to characterize the dynamic mechanical behaviour of ballistic yarns

    Science.gov (United States)

    Chevalier, C.; Kerisit, C.; Boussu, F.; Coutellier, D.; Faderl, N.; Klavzar, A.

    2016-10-01

    Fabrics have been widely used as part of ballistic protections since the 1970s and the development of new ballistic solutions made from fabrics need numerical simulations, in order to predict the performance of the ballistic protection. The performances and the induced mechanisms in ballistic fabrics during an impact depend on the weaving parameters and also on the inner parameters of the yarns used inside these structures. Thus, knowing the dynamic behaviour of yarn is essential to determine the ballistic behaviour of fabrics during an impact. Two major experimental devices exist and are used to test ballistic yarns in a dynamic uniaxial tension. The first one corresponds to the Split Hopkinson Tensile Bars device, which is commonly used to characterize the mechanical properties of materials in uniaxial tension and under high loading. The second one is the transversal impact device. The real conditions of ballistic impact can be realized with this device. Then, this paper deals with a new experimental setup developed in our laboratory and called the ‘tensile impact test for yarn’ (TITY) device. With this device, specific absorbed energy measurements of para-aramid yarns (336 Tex, Twaron™, 1000 filaments) have been carried out and revealed that static and dynamic properties of para-aramid are different.

  15. Mechanical Behaviour of Inconel 718 Thin-Walled Laser Welded Components for Aircraft Engines

    Directory of Open Access Journals (Sweden)

    Enrico Lertora

    2014-01-01

    Full Text Available Nickel alloys are very important in many aerospace applications, especially to manufacture gas turbines and aero engine components, where high strength and temperature resistance are necessary. These kinds of alloys have to be welded with high energy density processes, in order to preserve their high mechanical properties. In this work, CO2 laser overlap joints between Inconel 718 sheets of limited thickness in the absence of postweld heat treatment were made. The main application of this kind of joint is the manufacturing of a helicopter engine component. In particular the aim was to obtain a specific cross section geometry, necessary to overcome the mechanical stresses found in these working conditions without failure. Static and dynamic tests were performed to assess the welds and the parent material fatigue life behaviour. Furthermore, the life trend was identified. This research pointed out that a full joint shape control is possible by choosing proper welding parameters and that the laser beam process allows the maintenance of high tensile strength and ductility of Inconel 718 but caused many liquation microcracks in the heat affected zone (HAZ. In spite of these microcracks, the fatigue behaviour of the overlap welds complies with the technical specifications required by the application.

  16. Mechanical Characterization and Water Absorption Behaviour of Interwoven Kenaf/PET Fibre Reinforced Epoxy Hybrid Composite

    Directory of Open Access Journals (Sweden)

    Yakubu Dan-mallam

    2015-01-01

    Full Text Available The development of interwoven fabric for composite production is a novel approach that can be adopted to address the challenges of balanced mechanical properties and water absorption behaviour of polymer composites. In this paper, kenaf and PET (polyethylene terephthalate fibre were selected as reinforcing materials to develop the woven fabric, and low viscosity epoxy resin was chosen as the matrix. Vacuum infusion process was adopted to produce the hybrid composite due to its superior advantages over hand lay-up technique. The weight percentage composition of the Epoxy/kenaf/PET hybrid composite was maintained at 70/15/15 and 60/20/20, respectively. A significant increase in tensile strength and elastic modulus of approximately 73% and 53% was recorded in relation to neat epoxy. Similarly, a substantial increase in flexural, impact, and interlaminar properties was also realized in relation to neat epoxy. This enhancement in mechanical properties may be attributed to the interlocking structure of the interwoven fabric, individual properties of kenaf and PET fibres, strong interfacial bonding, and resistance of the fibres to impact loading. The water absorption of the composites was studied by prolonged exposure in distilled water, and the moisture absorption pattern was found to follow Fickian behaviour.

  17. High Strain-Rate Mechanical Behaviour of a Copper Matrix Composite for Nuclear Applications

    CERN Document Server

    Peroni, L

    2012-01-01

    Aim of this work is the investigation of mechanical behaviour of an alumina dispersion strengthened copper, known by the trade name GLIDCOP®, subjected to dynamic loads: it is a composite material with a copper matrix strengthened with aluminium oxide ceramic particles. Since the particle content is quite small the material keeps the OFE copper physical properties, such as thermal and electrical conductivity, but with a higher yield strength, like a mild-carbon steel. Besides, with the addition of aluminium oxide, the good mechanical properties are retained also at high temperatures and the resistance to thermal softening is increased: the second phase blocks the dislocation movement preventing the grain growth. Thanks to these properties GLIDCOP® finds several applications in particle accelerator technologies, where problems of thermal management, combined with structural requirements, play a key role. Currently, it is used for the construction of structural and functional parts of the particle beam collim...

  18. Mechanical and microstructural behaviour of Y{sub 2}O{sub 3} ODS EUROFER 97

    Energy Technology Data Exchange (ETDEWEB)

    Castro, V. de [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain)]. E-mail: mvcastro@fis.uc3m.es; Leguey, T. [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Munoz, A. [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Monge, M.A. [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Fernandez, P. [CIEMAT, Avda. Complutense 22, 28040 Madrid (Spain); Lancha, A.M. [CIEMAT, Avda. Complutense 22, 28040 Madrid (Spain); Pareja, R. [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain)

    2007-08-01

    Two small ingots of the steel EUROFER 97, one containing 0.25 wt% Y{sub 2}O{sub 3} and the other Y{sub 2}O{sub 3} free, have been produced by consolidating mechanically milled powder by hot isostatic pressing at 1373 K for 2 h under 200 MPa. For comparison, a third ingot was consolidated under identical conditions but using un-milled EUROFER powder. Microhardness, tensile and Charpy tests, along with TEM observations, have been performed on these materials in the as-HIPed condition and after different heat treatments. The mechanical behaviour and the microstructural characteristics of these materials suggest that the origin of the reduced impact properties of the oxide dispersion strengthened EUROFER could be the premature formation of carbides during quenching following the HIP process. This would be enhanced by the high density of structural defects produced by milling, as these favour the fast diffusion and segregation of carbon.

  19. UNDERSTANDING THE MECHANICAL PROPERTIES OF SINGLE MICRO-PARTICLES AND THEIR COMPACTION BEHAVIOUR

    Institute of Scientific and Technical Information of China (English)

    Siaw Fung Yap; Michael Adams; Jonathan Seville; Zhibing Zhang

    2006-01-01

    The compaction of particulate materials to form tablets is increasingly employed as a final dosage form for functional products due to its simplicity and low cost. However, the functionality of some products may be impaired due to the high compression pressures required. The general aim of the current study is to understand the relationship between the mechanical properties of single feed particles (<100μm) and their compaction behaviour in order to produce tablets at low compression pressure with acceptable strength. The materials studied were pharmaceutical excipients, comprising three enteric polymer particles and three different powders in the form of agglomerates. The mechanical properties of the individual particles or agglomerates were determined by a micromanipulation technique. The samples were also compacted in cylindrical tableting dies. It was observed that there was a strong correlation between the forces required to cause the fracture of the single particles and those derived from the compaction measurements as determined using an existing analysis.

  20. Mechanical behaviour near grain boundaries of He-implanted UO2 ceramic polycrystals

    Science.gov (United States)

    Ibrahim, M.; Castelier, É.; Palancher, H.; Bornert, M.; Caré, S.; Micha, J.-S.

    2017-01-01

    For studying the micromechanical behaviour of UO2 and characterising the intergranular interaction, polycrystals are implanted with helium ions, inducing strains in a thin surface layer. Laue X-ray micro-diffraction is used to measure the strain field in this implanted layer with a spatial resolution of about 1 μm. It allows a 2D mapping of the strain field in a dozen of grains. These measurements show that the induced strain depends mainly on the crystal orientation, and can be evaluated by a semi-analytical mechanical model. A mechanical interaction of the neighbouring grains has also been evidenced near the grain boundaries, which has been well reproduced by a finite element model. This interaction is shown to increase with the implantation energy (i.e. the implantation depth): it can be neglected at low implantation energy (60 keV), but not at higher energy (500 keV).

  1. Mechanical behaviour study on SBR/EVA composite for FDM feedstock fabrication

    Science.gov (United States)

    Raveverma, P.; Ibrahim, M.; Sa'ude, N.; Yarwindran, M.; Nasharuddin, M.

    2017-04-01

    This paper presents the research development of a new SBR/EVA composite flexible feedstock material by the injection moulding machine. The material consists of poly (ethylene-co-vinyl acetate) in styrene butadiene rubber cross-linked by Dicumyl Peroxide. In this study, the mechanical behaviour of injection moulded SBR/EVA composite with different blend ratio investigated experimentally. The formulations of blend ratio with several combinations of a new SBR/EVA flexible feedstock was done by volume percentage (vol. %). Based on the result obtained from the mechanical testing done which is tensile and hardness the composite of SBR/EVA has the high potency to be fabricated as the flexible filament feedstock. The ratio of 80:20 which as an average hardness and tensile strength proved to be the suitable choice to be fabricated as the flexible filament feedstock. The study has reached its goals on the fabricating and testing a new PMC which is flexible.

  2. Endoscopic treatment of duodenal varices with cyanoacrylate

    Directory of Open Access Journals (Sweden)

    Ana Mora-Soler

    2013-12-01

    Full Text Available Background: the duodenum is the most common location for ectopic varices. Bleeding is rare, but when it appears, it is massive and difficult to control. Material and methods: retrospective description of five clinical cases of digestive bleeding secondary to duodenal varices that we observed between the years 2011 and 2012, together with their clinical characteristics, endoscopic diagnosis, endoscopic treatment with cyanoacrylate injection and the posterior follow-up and assessment of new bleeding. Results: all five patients were treated with an endoscopic cyanoacrylate injection and two of the patients experienced a digestive rebleeding. Three of the patients died during the follow-up period, only one due to cause digestive bleeding. Conclusion: in conclusion we can state that endoscopic treatment of duodenal varices with cyanoacrylate is technically possible, and it permits us to control the first bleeding before doing other definitive treatments, if the patient condition allows it.

  3. Pancreatic-induced Intramural Duodenal Haematoma

    Directory of Open Access Journals (Sweden)

    Julius K. Ma

    2008-04-01

    Full Text Available Spontaneous intramural duodenal haematoma (IDH is an uncommon pathology and it is usually related to anticoagulant therapy. Other causes include various pancreatic diseases, connective tissue disease, peptic ulcer disease and pancreaticoduodenal aneurysm. IDH of pancreatic origin has been infrequently reported. The disease course can be life-threatening and serious complications may occur, including gastric outlet obstruction, duodenal perforation and septicaemia. A case of pancreatic-induced IDH is presented, for which pancreaticoduodenectomy was performed as definitive treatment. In general, medical treatment with continuous nasogastric aspiration and total parenteral nutrition is recommended as initial management strategy. Surgical interventions (evacuation of blood clot or surgical resection are reserved for patients in whom medical treatment fails or complications occur.

  4. Duodenal damage complicating percutaneous access to kidney

    OpenAIRE

    Antonio Corrêa Lopes Neto; Marcos Tobias-Machado; Roberto Vaz Juliano; Marco Aurélio Lipay; Milton Borrelli; Eric Roger Wroclawski

    2000-01-01

    CONTEXT: Since the first percutaneous nephrostomy performed by Goodwin in 1954, technical advances in accessing the kidneys via percutaneous puncture have increased the use of this procedure and thus the complications too. Among these complications, digestive tract damage is not common. DESIGN: Case report. CASE REPORT: We report a duodenal lesion that was corrected using surgical exploration and we touch on the therapeutic options, which may be conservative or interventionist. We chose conse...

  5. Duodenal Perforation Precipitated by Scrub Typhus

    OpenAIRE

    Raghunath Rajat; David Deepu; Arul Jeevan Jonathan; Abhilash Kundavaram Paul Prabhakar

    2015-01-01

    Scrub typhus is an acute febrile illness usually presenting with fever, myalgia, headache, and a pathognomonic eschar. Severe infection may lead to multiple organ failure and death. Gastrointestinal tract involvement in the form of gastric mucosal erosions and ulcerations owing to vasculitis resulting in gastrointestinal bleeding is common. This process may worsen a pre-existent asymptomatic peptic ulcer, causing duodenal perforation, and present as an acute abdomen requiring surgical explora...

  6. Portal hypertensive duodenal polyp: A case report

    Institute of Scientific and Technical Information of China (English)

    Jean-David Zeitoun; Ariane Chryssostalis; Benoit Terris; Frederic Prat; Marianne Gaudric; Stanislas Chaussade

    2007-01-01

    Abnormalities of gastric mucosa in patients with portal hypertension are well documented. Manifestations of portal hypertension in small bowel and colon are less common. Colonic polypoid lesions microscopically consisting of a normal mucosa, with dilatation of submucosal vessels, have been described. We here report the first case of portal hypertensive duodenal polyp, responsible for gastro-intestinal bleeding.Endoscopic treatment turned out to be successful.

  7. [Perforated duodenal diverticulum: report of a case].

    Science.gov (United States)

    Gulotta, G; Agosta, G; Romano, G

    2001-01-01

    After the colon, the duodenum is the most common site of diverticula. Duodenal diverticula can be divided into two types: intraluminal or extraluminal. The latter are more frequent, with a prevalence ranging from 0.6 to 27% in relation to the diagnostic methods utilized. Females are more often affected than males. About 70-75% of extraluminal duodenal diverticula are located in a circular area centred around the ampulla of Vater within a radius of 2-3 cm; these are defined as periampullary or juxtapapillary. Perforation is the rarest type of complication and can simulate different clinical conditions. CT plays a fundamental role in diagnosis also in relation to the different diverticular topography. Perforation is an indication for emergency surgery. The authors describe the clinical case of a duodenal diverticulum containing the outlet of the papilla, complicated by perforation; CT showed retroduodenal fluid and free air. Emergency surgery with an external biliary drainage, naso-biliary probe, and a diverticulo-jejunostomy on a Roux-en-Y defunctionalised loop, resolved the condition.

  8. Effect of carbonate content on the mechanical behaviour of clay fault-gouges

    Science.gov (United States)

    Bakker, Elisenda; Niemeijer, André; Hangx, Suzanne; Spiers, Chris

    2015-04-01

    Carbon dioxide capture and storage (CCS) in depleted oil and gas reservoirs is considered to be the most promising technology to achieve large-scale reduction in anthropogenic emissions. In order to retain the stored CO2 from the atmosphere for the very long-term, i.e. on timescales of the order of 103-104 years, it is essential to maintain the integrity of the caprock, and more specifically of any faults penetrating the seal. When selecting suitable CO2-storage reservoirs, pre-exisiting faults within the caprock require close attention, as changes in the stress state resulting from CO2-injection may induce fault slip motion which might cause leakage. Little is known about the effect of fluid-rock interactions on the mineral composition, mechanical properties and the integrity and sealing capacity of the caprock. Previous studies on the effect of mineral composition on the frictional properties of fault gouges have shown that friction is controlled by the dominant phase unless there is a frictionally weak, through-going fabric. However, the effect on stability is less clear. Since long-term CO2-exposure might cause chemical reactions, potentially resulting in the dissolution or precipitation of carbonate minerals, a change in mineralogy could affect the mechanical stability of a caprock significantly. Calcite, for example, is known to be prone to micro-seismicity and shows a transition from velocity-strengthening to velocity-weakening behaviour around 100-150°C. Therefore, we investigated the effect of varying clay:carbonate ratios on fault friction behaviour, fault reactivation potential and slip stability, i.e. seismic vs. aseismic behaviour. Three types of simulated fault gouges were used: i) carbonate-free, natural clay-rich caprock samples, consisting of predominantly phyllosilicates (~80%) and quartz ~20%), ii) pure calcite, and iii) mixtures of carbonate-free clay-rich caprock and pure calcite, with predetermined clay:carbonate ratios. For the natural clay

  9. Real-time and non-invasive measurements of cell mechanical behaviour with optical coherence phase microscopy

    Science.gov (United States)

    Gillies, D.; Gamal, W.; Downes, A.; Reinwald, Y.; Yang, Y.; El Haj, A.; Bagnaninchi, P. O.

    2017-02-01

    There is an unmet need in tissue engineering for non-invasive, label-free monitoring of cell mechanical behaviour in their physiological environment. Here, we describe a novel optical coherence phase microscopy (OCPM) set-up which can map relative cell mechanical behaviour in monolayers and 3D systems non-invasively, and in real-time. 3T3 and MCF-7 cells were investigated, with MCF-7 demonstrating an increased response to hydrostatic stimulus indicating MCF-7 being softer than 3T3. Thus, OCPM shows the ability to provide qualitative data on cell mechanical behaviour. Quantitative measurements of 6% agarose beads have been taken with commercial Cell Scale Microsquisher system demonstrating that their mechanical properties are in the same order of magnitude of cells, indicating that this is an appropriate test sample for the novel method described.

  10. Microstructural, mechanical and electrochemical behaviour of a 7017 Al–Zn–Mg alloy of different tempers

    Energy Technology Data Exchange (ETDEWEB)

    Rout, Prasanta Kumar, E-mail: prasantonnet55@yahoo.com; Ghosh, M.M.; Ghosh, K.S., E-mail: ksghosh2001@yahoo.co.uk

    2015-06-15

    The aim of the investigation is to assess the microstructural features and associated physical, mechanical and electrochemical properties of a 7017 Al–Zn–Mg alloy of various tempers. A 7017 Al–Zn–Mg alloy was subjected to different ageing schedules to produce under-(T4), peak-(T6), over-(T7) and highly over-aged tempers. Optical microscopy, hardness measurement, electrical conductivity measurement, tensile testing and SEM fractographs, differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and electrochemical polarization studies have been used to characterize the alloy tempers. Hardness measurement and tensile testing showed the characteristic age hardening phenomenon of aluminium alloys. Optical and TEM micrographs have revealed the variation in size of matrix strengthening η′ (MgZn{sub 2}) and also the size and distribution of grain boundary η (MgZn{sub 2}) precipitate with ageing time. DSC thermograms exhibiting exothermic and endothermic peaks indicated the characteristic solid state reaction sequence of the 7017 alloy. Potentiodynamic polarization study of the 7017 alloy of various tempers in 3.5 wt.% NaCl solution at near neutral pH showed typical active metal dissolution behaviour, but at pH 12 an active–passive–transpassive transition behaviour has been observed. - Graphical abstract: TEM micrograph of the 7017 aluminium alloy of various tempers (a, b) under aged (T4), (c, d) peak aged (T6), (e, f) over aged (T7) and (g, h) highly over-aged. Display Omitted - Highlights: • 7017 Al-Zn-Mg alloy was subjected to different artificial ageing treatments. • Characterization of 7017 alloy tempers by hardness, tensile, DSC, TEM and electrochemical behaviour. • Structure-properties relationship of the 7017 Al-Zn-Mg alloy of various tempers.

  11. Dynamic tensile behaviour and deformational mechanism of C5191 phosphor bronze under high strain rates deformation

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Dao-chun [College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); College of Mechanical and Electrical Engineering, Taizhou Vocational & Technical College, Taizhou 318000 (China); Chen, Ming-he, E-mail: meemhchen@nuaa.edu.cn [College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Wang, Lei; Cheng, Hu [College of Mechanical Engineering, Taizhou University, Taizhou 318000 (China)

    2016-01-01

    High speed stamping process is used to high strength and high electrical conductivity phosphor bronze with extremely high strain rates more than 10{sup 3} s{sup −1}. This study on the dynamic tensile behaviour and deformational mechanism is to optimise the high speed stamping processes and improve geometrical precision in finished products. Thus, the tensile properties and deformation behaviour of C5191 phosphor bronze under quasi-static tensile condition at a strain rate of 0.001 s{sup −1} by electronic universal testing machine, and dynamic tensile condition at strain rate of 500, 1000 and 1500 s{sup −1} by split Hopkinson tensile bar (SHTB) apparatus were studied. The effects of strain rate and the deformation mechanism were investigated by means of SEM and TEM. The results showed that the yield strength and tensile strength of C5191 phosphor bronze under high strain rates deformation increased by 32.77% and 11.07% respectively compared with quasi-static condition, the strain hardening index increases from 0.075 to 0.251, and the strength of the material strain rates sensitivity index change from 0.005 to 0.022, which presented a clear sensitive to strain rates. Therefore, it is claimed that the dominant deformation mechanism was changed by the dislocation motion under different strain rates, and the ability of plastic deformation of C5191 phosphor bronze increased due to the number of movable dislocations increased significantly, started multi-line slip, and the soft effect of adiabatic temperature rise at the strain rate ranging from 500 to 1500 s{sup −1}.

  12. Multiaxial mechanical behaviour of the passive ureteral wall: experimental study and mathematical characterisation.

    Science.gov (United States)

    Sokolis, Dimitrios P

    2012-01-01

    There is a scarcity of data regarding the mechanical properties of the ureter, although this would facilitate our understanding of its physiology and pathophysiology, and the development of suitable biomaterials for replacement. There is hence an urgent need for multiaxial experimental data and methodical constitutive formulations, which we aim at presenting through this report. The zero-stress state of wall tissue, serving as the starting geometry for biomechanical analyses, was accordingly determined and the 3D passive behaviour of ureteral specimens, isolated from healthy rabbits, was studied under a physiologic range of finite inflation and longitudinal extension. Two most-commonly employed descriptors of soft tissue behaviour were chosen to fit the material response: the Fung-type strain-energy function (SEF) and its combination with a quadratic function. Both SEFs were tested in the thick-walled setting, with incompressibility enforced explicitly or via a Lagrange multiplier. The deformational response of the ureter exhibited an exponential and not the sigmoidal dependency on pressure that requests implementation of two-term SEFs. Indeed, the four-parameter Fung-type SEF resulted in reasonable fit of both the external radius and longitudinal force vs. lumen pressure data, and fitting accuracy was not improved when attempting the seven-parameter Fung-type or biphasic SEFs. There were also serious over-parameterisation problems with those models, favouring the implementation of the SEF with the smallest number of parameters. The material parameters optimised revealed significant mechanical anisotropy, with longitudinal properties being stiffer than circumferential ones under equibiaxial stress states. We conclude that ureter displays a nonlinear anisotropic mechanical response that is well-characterised by the four-parameter Fung-type SEF.

  13. Russell body duodenitis with immunoglobulin kappa lightchain restriction

    Institute of Scientific and Technical Information of China (English)

    William R Munday; Lucy Harn Kapur; Mina Xu; Xuchen Zhang

    2015-01-01

    Russell bodies are eosinophilic intracytoplasmicglobules which are likely the result of disturbedsecretion of immunoglobulins that accumulate withinthe plasma cell. Russell body collections have beenidentified within the stomach, known as Russellbody gastritis. Similar lesions within the duodenumare referred to as Russell body duodenitis, whichis rare. Several Russell body gastritis case reportsare associated with Helicobacter pylori . However,the etiology of Russell body duodenitis remainsunclear. Here we report the first case of Russell bodyduodenitis with immunoglobulin light chain restrictionin a background of peptic duodenitis.

  14. Perforated duodenal diverticulum caused by Bezoar: A case report

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eun Jung; Moon, Sung Kyoung; Park, Seong Jin; Lim, Joo Won; Lee, Dong Ho; Ko, Young Tae [Dept. of Radiology, College of Medicine, Kyung Hee University, Seoul (Korea, Republic of)

    2013-11-15

    Duodenal diverticulum is common, but its perforation is a rare complication. Duodenal diverticulum perforation requires prompt treatments because of its high mortality rate. However, an accurate diagnosis is difficult to make due to nonspecific symptoms and signs. It can be misdiagnosed as pancreatitis, cholecystitis, or peptic ulcer. Herein, we report a case of perforated duodenal diverticulum caused by bezoar in a 33-year-old woman whom was diagnosed by abdomen computed tomography and ultrasonography.

  15. A DYNAMIC MECHANICAL ANALYSIS STUDY OF THE TRANSITION BEHAVIOUR OF Ⅰ-PP/EPDM BLENDS

    Institute of Scientific and Technical Information of China (English)

    DONG Lisong; ZHUANG Yugang; LI Shichun; FENG Zhiliu

    1992-01-01

    The transition behaviour of the blends of isotactic polypropylene (i-PP ) with ethylene-propylene terpolymer (EPDM) containing 42 wt% propylene was investigated by dynamic mechanical analysis technique (DMA). Owing to its high propylene content, EPDM is compatible with i-PP to some degree. The interaction between the two components was strengthened. As expected, for partially compatible system the glass transition temperature of i-PP in the blends shifted to lower temperature. It was found that there existed two transitions, αEPDM and βEPDM, for the EPDM used in this work.The former was considered to be the glass transition of the random chain segments of EPDM, while the latter the local motion of the long ethylene sequences in EPDM. The unusual transition behaviour of αEPDM in the blends was explained in terms of the greater thermal expansion of EPDM and the compatibility of the two components. On the other hand, the β EPDM changed with the composition of the blends in a regular manner.

  16. Tribological behaviour of mechanically synthesized titanium-boron carbide nanostructured coating.

    Science.gov (United States)

    Aliofkhazraei, M; Rouhaghdam, A Sabour

    2012-08-01

    In this paper, titanium-boron carbide (Ti/B4C) nanocomposite coatings with different B4C nanoparticles contents were fabricated by surface mechanical attrition treatment (SMAT) method by using B4C nanoparticles with average nanoparticle size of 40 nm. The characteristics of the nanopowder and coatings were evaluated by microhardness test, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Friction and wear performances of nanocomposite coatings and pure titanium substrate were comparatively investigated, with the effect of the boron carbide content on the friction and wear behaviours to be emphasized. The results show the microhardness, friction and wear behaviours of nanocomposite coatings are closely related with boron carbide nanoparticle content. Nanocomposite coating with low B4C content shows somewhat (slight) increased microhardness and wear resistance than pure titanium substrate, while nanocomposite coating with high B4C content has much better (sharp increase) wear resistance than pure titanium substrate. The effect of B4C nanoparticles on microhardness and wear resistance was discussed.

  17. Modelling of the mechanical behaviour of two pure PTFE powders during their compaction at room temperature

    Science.gov (United States)

    Frédy, Carole; Canto, Rodrigo B.; Schmitt, Nicolas; Roux, Stéphane; Billardon, René

    2013-06-01

    Since PolyTetraFluoroEthylene (PTFE) is not melt processible because of its very high melt viscosity, parts made of this material are generally manufactured by cold compaction of powder material followed by sintering of the green compact. The aim of this study is to identify 3-D constitutive equations suitable for the finite element analysis of PTFE powder compaction. To exhibit the influence of their geometrical aspect on their mechanical behaviour, two pure PTFE resins were tested, viz. a free flowing pelletized resin and a granular fine cut resin. To study the behaviour of these powders during their compaction along different loading paths, a novel triaxial device has been designed and installed on a six-actuator triaxial testing machine. The results obtained for hydrostatic loading were favourably compared with results obtained by isostatic pressing. Various complex loading paths were also investigated. Full 3D elasto-viscoplastic non-associated constitutive equations, viz. a non-linear Drucker-Prager/cap type model, could be identified.

  18. Diagnosis and treatment of 34 cases of blunt duodenal injuries

    Institute of Scientific and Technical Information of China (English)

    BAO Shi-ting; WANG San-ming

    2007-01-01

    Objective: To summarize the experience on diagnosis and treatment of blunt duodenal injuries, and thus to improve the therapeutic skills. Methods: Clinical data of 34 cases of blunt duodenal injuries admitted to our hospital from 1990 to 2006 were retrospectively analyzed. Results: Among them, 28 cases were cured, 20 cases presented with complications, and 6 cases died. The causes of death were: duodenal or pancreatic fistula in 2 cases, intra- and retroperitoneal infection complicating septicopyemia in 2, disseminated intravascular coagulation in 1 and multiple organ failure in 1. Conclusions: Misdiagnosis and missed diagnosis predispose to happen for blunt duodenal injuries. Early recognition and surgical intervention are critical to a successful rescue.

  19. Russell body duodenitis with immunoglobulin kappa light chain restriction.

    Science.gov (United States)

    Munday, William R; Kapur, Lucy Harn; Xu, Mina; Zhang, Xuchen

    2015-01-16

    Russell bodies are eosinophilic intracytoplasmic globules which are likely the result of disturbed secretion of immunoglobulins that accumulate within the plasma cell. Russell body collections have been identified within the stomach, known as Russell body gastritis. Similar lesions within the duodenum are referred to as Russell body duodenitis, which is rare. Several Russell body gastritis case reports are associated with Helicobacter pylori. However, the etiology of Russell body duodenitis remains unclear. Here we report the first case of Russell body duodenitis with immunoglobulin light chain restriction in a background of peptic duodenitis.

  20. High-resolution analysis of the duodenal interdigestive phase III in humans.

    Science.gov (United States)

    Castedal, M; Abrahamsson, H

    2001-10-01

    To study the spatial organization of the propagating pressure waves of duodenal phase III, we performed fasting antroduodenal high-resolution manometry with a 16-channel catheter in 12 healthy subjects. The phase III pressure waves diverged in an anterograde and retrograde direction from the start site of each pressure wave. The pressure waves maintained this configuration as the activity front moved distally in the duodenum. The start site of the pressure waves moved gradually to a point approximately 12 cm (median) distal to the pylorus and remained at this point for about 40% of the phase III time before moving further distally. The length of retrograde pressure wave propagation increased to 6 cm (median) as the pressure wave origin moved aborally to a point 10-14 cm distal to the pylorus, and then decreased when the origin of pressure waves reached the distal end of the duodenum. Bidirectional pressure waves dominated in both retrograde and anterograde activity fronts. Three pressure-wave mechanisms behind the duodenal phase IV were observed. Isolated pyloric pressure waves were absent during late duodenal phase III retroperistalsis. Thus, a number of new features of the duodenal phase III-related motility were observed using high-temporospatial resolution recordings.

  1. Mechanical Behaviour of Glassy Composite Seals for IT-SOFC Application

    DEFF Research Database (Denmark)

    Nielsen, Karsten Agersted; Solvang, Mette; Nielsen, Sofie Birkedal Lund

    2007-01-01

    Glass-based sealants have been developed with emphasis on filler material and surface treatment of the sealing components in order to optimise their mechanical and functional behaviour during the initial sealing process as well as during thermal cycling of the SOFC-stack after exposure to operating...... conditions. The bonding strength and microstructure of the interfaces between composite seals and interconnect materials were investigated as a function of surface treatment of the sealing surfaces, glass matrix composition, sealing pressure and temperature. The initial sealing performance and resistance...... to thermal cycling were then investigated on selected combinations of materials after ageing. Strongest bonding between sodium aluminosilicate glass composite and steel surfaces was obtained for sealing at 850°C. For the strongest interface, having shear strength of 2.35 MPa, rupture occurred in the glass...

  2. Coupled phenomenological and fracture mechanics approach to assess the fracture behaviour of TWC piping component

    Energy Technology Data Exchange (ETDEWEB)

    Saxena, Sanjeev, E-mail: san_bpl@yahoo.co [Advanced Materials and Processes Research Institute (AMPRI), CSIR Concern, Hoshangabad Road, Bhopal 462026 (India); Ramakrishnan, N. [Advanced Materials and Processes Research Institute (AMPRI), CSIR Concern, Hoshangabad Road, Bhopal 462026 (India); Chouhan, J.S. [Civil Engineering Department, Samrat Ashok Technological Institute, Vidisha (India)

    2010-04-15

    The present study demonstrates the numerical prediction of experimental specimen J-R curve using Gurson-Tvergaard-Needleman phenomenologically based material model. The predicted specimen J-R curve is used to determine the geometric independent initiation fracture toughness (J{sub SZWc}) value that compares well with experimental result. Using the experimentally determined and numerically predicted J{sub SZWc} values and specimen J-R curves, the accuracy of predicting the fracture behaviour of the cracked component is judged. Thus the present study proposed a coupled phenomenological and fracture mechanics approach to predict the crack initiation and instability stages in cracked piping components using numerically predicted specimen J-R curve obtained from tensile specimens testing data.

  3. Identifying the nonlinear mechanical behaviour of micro-speakers from their quasi-linear electrical response

    Science.gov (United States)

    Zilletti, Michele; Marker, Arthur; Elliott, Stephen John; Holland, Keith

    2017-05-01

    In this study model identification of the nonlinear dynamics of a micro-speaker is carried out by purely electrical measurements, avoiding any explicit vibration measurements. It is shown that a dynamic model of the micro-speaker, which takes into account the nonlinear damping characteristic of the device, can be identified by measuring the response between the voltage input and the current flowing into the coil. An analytical formulation of the quasi-linear model of the micro-speaker is first derived and an optimisation method is then used to identify a polynomial function which describes the mechanical damping behaviour of the micro-speaker. The analytical results of the quasi-linear model are compared with numerical results. This study potentially opens up the possibility of efficiently implementing nonlinear echo cancellers.

  4. Keep your eyes on development - The behavioural and neurophysiological development of visual mechanisms underlying form processing

    Directory of Open Access Journals (Sweden)

    Carlijn eVan Den Boomen

    2012-03-01

    Full Text Available Visual form perception is essential for correct interpretation of, and interaction with, our environment. Form perception depends on visual acuity and processing of specific form characteristics, such as luminance contrast, spatial frequency, colour, orientation, depth and even motion information. As other cognitive processes, form perception matures with age. This paper aims at providing a concise overview of our current understanding of the typical development, from birth to adulthood, of form-characteristic processing, as measured both behaviourally and neurophysiologically. Two main conclusions can be drawn. First, the current literature conveys that for most reviewed characteristics a developmental pattern is apparent. These trajectories are discussed in relation to the organisation of the visual system. The second conclusion is that significant gaps in the literature exist for several age-ranges. To complete our understanding of the typical and, by consequence, atypical development of visual mechanisms underlying form processing, future research should uncover these missing segments.

  5. Growth, photoluminescence, thermal and mechanical behaviour of Ethyltriphenylphosphonium bromide dihydrate crystal

    Science.gov (United States)

    Parthasarathy, M.; Gopalakrishnan, R.

    2013-10-01

    Single crystal of Ethyltriphenylphosphonium bromide dihydrate (ETPB) was grown by slow evaporation solution growth technique. The grown crystal was confirmed by single crystal X-ray diffraction. The functional groups and vibrational frequencies were identified using FT-IR and FT-Raman spectral analyses. Optical properties were studied by UV-Visible and photoluminescence spectroscopic techniques to explore its efficacy towards device fabrication. Thermal characteristics of ETPB were studied using the TGA/DTA and DSC response curves. The mechanical behaviour of the grown crystal was studied using Vicker's microhardness tester and the work hardening coefficient was evaluated. The second harmonic generation of the title compound was tested by Kurtz-Perry powder technique.

  6. Production and Mechanical Behaviour of Biomedical CoCrMo Alloy

    Institute of Scientific and Technical Information of China (English)

    O.Sahin; A.Riza Tuncdemir; H.Ali Cetinkara; H.Salih Guder; E.Sahin

    2011-01-01

    Cobalt-based alloy(Co-30Cr-5.5Mo)is produced by the investment casting process.This alloy complies with the ASTM F75 standard and is widely used in the manufacturing of orthopedic implants because of its high strength,good corrosion resistance and excellent biocompatibility properties.SEM,XRD and microhardness tests are used to examine the mechanical properties of the material.The examined material exhibits the behaviour of indentation size effect(ISE).Our results reveal that Vickers and Knoop microhardness are dependent on indentation test load.The traditional Meyer's law,the proportional specimen resistance(PSR)model and the Hays-Kendall model(HK)are used to analyze the load dependence of the hardness.As a result,the Hays-Kendall model is found to be the most effective to determine the load-independent hardness HLI of CoCrMo alloy.%Cobalt-based alloy (Co-30Cr-5.5Mo) is produced by the investment casting process. This alloy complies with the ASTM F75 standard and is widely used in the manufacturing of orthopedic implants because of its high strength, good corrosion resistance and excellent biocompatibility properties. SEM, XRD and microhardness tests are used to examine the mechanical properties of the material. The examined material exhibits the behaviour of indentation size effect (ISE). Our results reveal that Vickers and Knoop microhardness are dependent on indentation test load. The traditional Meyer's law, the proportional specimen resistance (PSR) model and the Hays-Kendall model (HK) are used to analyze the load dependence of the hardness. As a result, the Hays-Kendall model is found to be the most effective to determine the load-independent hardness ifLI of CoCrMo alloy.

  7. Experimental approach and modelling of the mechanical behaviour of graphite fuel elements subjected to compression pulses

    Science.gov (United States)

    Forquin, P.

    2010-06-01

    Among the activities led by the Generation IV International Forum (GIF) relative to the future nuclear systems, the improvement of recycling of fuel elements and their components is a major issue. One of the studied systems by the GIF is the graphite-moderated high-temperature gas cooled reactor (HTGR). The fuel elements are composed of fuel roads half-inch in diameter named compacts. The compacts contain spherical particles made of actinide kernels about 500 m in diameter coated with three layers of carbon and silicon carbide, each about 50 m thick, dispersed in a graphite matrix. Recycling of compacts requires first a separation of triso-particles from the graphite matrix and secondly, the separation of the triso-coating from the kernels. This aim may be achieved by using pulsed currents: the compacts are placed within a cell filled by water and exposed to high voltage between 200 - 500 kV and discharge currents from 10 to 20 kA during short laps of time (about 2 µs) [1-2]. This repeated treatment leads to a progressive fragmentation of the graphite matrix and a disassembly of the compacts. In order to improve understanding of the fragmentation properties of compacts a series of quasi-static and dynamic experiments have been conducted with similar cylindrical samples containing 10% (volume fraction) of SiC particles coated in a graphite matrix. First, quasi-static compression tests have been performed to identify the mechanical behaviour of the material at low strain-rates (Fig.1). The experiments reveal a complex elasto-visco-plastic behaviour before a brittle failure. The mechanical response is characterised by a low yield stress (about 1 MPa), a strong strain-hardening in the loading phase and marked hysteresis-loops during unloading-reloading stages. Brittle failure is observed for axial stress about 13 MPa. In parallel, a series of flexural tests have been performed with the aim to characterise the quasi-static tensile strength of the particulate

  8. Experimental approach and modelling of the mechanical behaviour of graphite fuel elements subjected to compression pulses

    Directory of Open Access Journals (Sweden)

    Forquin P.

    2010-06-01

    Full Text Available Among the activities led by the Generation IV International Forum (GIF relative to the future nuclear systems, the improvement of recycling of fuel elements and their components is a major issue. One of the studied systems by the GIF is the graphite-moderated high-temperature gas cooled reactor (HTGR. The fuel elements are composed of fuel roads half-inch in diameter named compacts. The compacts contain spherical particles made of actinide kernels about 500 m in diameter coated with three layers of carbon and silicon carbide, each about 50 m thick, dispersed in a graphite matrix. Recycling of compacts requires first a separation of triso-particles from the graphite matrix and secondly, the separation of the triso-coating from the kernels. This aim may be achieved by using pulsed currents: the compacts are placed within a cell filled by water and exposed to high voltage between 200 – 500 kV and discharge currents from 10 to 20 kA during short laps of time (about 2 µs [1-2]. This repeated treatment leads to a progressive fragmentation of the graphite matrix and a disassembly of the compacts. In order to improve understanding of the fragmentation properties of compacts a series of quasi-static and dynamic experiments have been conducted with similar cylindrical samples containing 10% (volume fraction of SiC particles coated in a graphite matrix. First, quasi-static compression tests have been performed to identify the mechanical behaviour of the material at low strain-rates (Fig.1. The experiments reveal a complex elasto-visco-plastic behaviour before a brittle failure. The mechanical response is characterised by a low yield stress (about 1 MPa, a strong strain-hardening in the loading phase and marked hysteresis-loops during unloading-reloading stages. Brittle failure is observed for axial stress about 13 MPa. In parallel, a series of flexural tests have been performed with the aim to characterise the quasi-static tensile strength of the

  9. Characterization of the thermo-mechanical behaviour of Hemp fibres intended for the manufacturing oh high performance composites

    CERN Document Server

    Placet, Vincent

    2009-01-01

    In this paper, the thermo-mechanical behaviour of hemp fibres (Cannabis sativa L.) is investigated using a Dynamic Mechanical Analyser. Experiments are performed at a frequency of 1 Hz in the temperature range of 20 to 220\\degree C. When a periodic solicitation is applied to an elementary fibre, an increase of the fibre rigidity and a reduction of the damping capacity are observed. These evolutions aim at stabilization after an identified number of cycles, traducing a phenomenon of "adaptation". This specific mechanical behaviour certainly involves biochemical and/or structural modifications in the material organisation as microfibrils reorientation. In addition, the behaviour of hemp fibres is affected by temperature. Temperature acts as an activation factor but also as a degradation factor of the viscoelastic properties of fibres. The rigidity and the endurance of fibres are highly affected by thermal treatment at temperature above 150\\degree C to 180\\degree C. Taking into account these results, polypropyle...

  10. Effects of selected casting methods on mechanical behaviour of Al-Mg-Si alloy

    Directory of Open Access Journals (Sweden)

    Henry Kayode TALABI

    2014-11-01

    Full Text Available This study investigated the effects of selected casting methods on mechanical behaviour of Al-Mg-Si alloy. The casting methods used was spin, sand and die casting, these were done with a view to determine which of the casting methods will produce the best properties. The pure aluminium scrap, magnesium and silicon were subjected to chemical analysis using spectrometric analyzer, thereafter the charge calculation to determine the amount needed to be charged into the furnace was properly worked out and charged into the crucible furnace from which as-cast aluminium was obtained. The mechanical properties of the casting produced were assessed by hardness and impact toughness test. The optical microscopy and experimental density and porosity were also investigated. From the results it was observed that magnesium and silicon were well dispersed in aluminium matrix of the spin casting. It was observed from visual examination after machining that there were minimal defects. It was also observed that out of the three casting methods, spin casting possesses the best mechanical properties (hardness and impact toughness.

  11. The effects of tantalum addition on the microtexture and mechanical behaviour of tungsten for ITER applications

    Energy Technology Data Exchange (ETDEWEB)

    Tejado, E., E-mail: elena.tejado@mater.upm.es [Departamento de Ciencia de Materiales-CIME, ETSI Caminos, Canales y Puertos, Universidad Politécnica de Madrid, Madrid (Spain); Centro Nacional de Investigaciones Metalúrgicas (CSIC), Madrid (Spain); Carvalho, P.A. [Associação Euratom/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); ICEMS, Departamento de Bioengenharia, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Munoz, A. [Departamento de Física, Universidad Carlos III, Leganés (Spain); Dias, M. [Associação Euratom/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Correia, J.B. [Associação Euratom/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); LNEG, Laboratório Nacional de Energia e Geologia, Estrada do Paço do Lumiar, 1649-038 Lisboa (Portugal); and others

    2015-12-15

    Tungsten (W) and its alloys are very promising materials for producing plasma-facing components (PFCs) in the fusion power reactors of the near future, even as a structural part in them. However, whereas the properties of pure tungsten are suitable for a PFC, its structural applications are still limited due to its low toughness, ductile to brittle transition temperature and recrystallization behaviour. Therefore, many efforts have been made to improve its performance by alloying tungsten with other elements. Hence, in this investigation, the thermo-mechanical performance of two new tungsten-tantalum materials has been evaluated. Materials with W–5wt.%Ta and W–15wt.%Ta were processed by mechanical alloying (MA) and later consolidation by hot isostatic pressing (HIP), with distinct settings for each composition. Thus, it was possible to determine the relationship between the microstructure and the addition of Ta with the macroscopic mechanical properties. These were measured by means of hardness, flexural strength and fracture toughness, in the temperature range of 300–1473 K. The microstructure and the fracture surfaces features of the tested materials were analysed by Field Emission Scanning Electron Microscopy (FESEM).

  12. Effect of microstructure on the mechanical and damping behaviour of dragonfly wing veins.

    Science.gov (United States)

    Rajabi, H; Shafiei, A; Darvizeh, A; Dirks, J-H; Appel, E; Gorb, S N

    2016-02-01

    Insect wing veins are biological composites of chitin and protein arranged in a complex lamellar configuration. Although these hierarchical structures are found in many 'venous wings' of insects, very little is known about their physical and mechanical characteristics. For the first time, we carried out a systematic comparative study to gain a better understanding of the influence of microstructure on the mechanical characteristics and damping behaviour of the veins. Morphological data have been used to develop a series of three-dimensional numerical models with different material properties and geometries. Finite-element analysis has been employed to simulate the mechanical response of the models under different loading conditions. The modelling strategy used in this study enabled us to determine the effects selectively induced by resilin, friction between layers, shape of the cross section, material composition and layered structure on the stiffness and damping characteristics of wing veins. Numerical simulations suggest that although the presence of the resilin-dominated endocuticle layer results in a much higher flexibility of wing veins, the dumbbell-shaped cross section increases their bending rigidity. Our study further shows that the rubber-like cuticle, friction between layers and material gradient-based design contribute to the higher damping capacity of veins. The results of this study can serve as a reference for the design of novel bioinspired composite structures.

  13. The effects of tantalum addition on the microtexture and mechanical behaviour of tungsten for ITER applications

    Science.gov (United States)

    Tejado, E.; Carvalho, P. A.; Munoz, A.; Dias, M.; Correia, J. B.; Mardolcar, U. V.; Pastor, J. Y.

    2015-12-01

    Tungsten (W) and its alloys are very promising materials for producing plasma-facing components (PFCs) in the fusion power reactors of the near future, even as a structural part in them. However, whereas the properties of pure tungsten are suitable for a PFC, its structural applications are still limited due to its low toughness, ductile to brittle transition temperature and recrystallization behaviour. Therefore, many efforts have been made to improve its performance by alloying tungsten with other elements. Hence, in this investigation, the thermo-mechanical performance of two new tungsten-tantalum materials has been evaluated. Materials with W-5wt.%Ta and W-15wt.%Ta were processed by mechanical alloying (MA) and later consolidation by hot isostatic pressing (HIP), with distinct settings for each composition. Thus, it was possible to determine the relationship between the microstructure and the addition of Ta with the macroscopic mechanical properties. These were measured by means of hardness, flexural strength and fracture toughness, in the temperature range of 300-1473 K. The microstructure and the fracture surfaces features of the tested materials were analysed by Field Emission Scanning Electron Microscopy (FESEM).

  14. Walking with insects. Molecular mechanisms behind parasitic manipulation of host behaviour

    NARCIS (Netherlands)

    Houte, van S.; Ros, V.I.D.; Oers, van M.M.

    2013-01-01

    Parasitic infections are often followed by changes in host behaviour. Numerous and exquisite examples of such behavioural alterations are known, covering a broad spectrum of parasites and hosts. Most descriptions of such parasite-induced changes in host behaviour are observational reports, while exp

  15. Health Behaviours As a Mechanism in the Prospective Relation between Workplace Reciprocity and Absenteeism: A Bridge too Far ?

    Directory of Open Access Journals (Sweden)

    Bart De Clercq

    Full Text Available The persistent lack of evidence on causal mechanisms between social capital and health threatens the credibility of the social capital-health association. The present study aims to address this ongoing problem by investigating whether health behaviours (i.e. smoking, alcohol consumption, and physical activity mediate the prospective relation between workplace reciprocity and future sickness absence.A cohort of 24,402 Belgian employees was followed up during 12 months for sickness absence. Workplace reciprocity was measured with four indicators-colleague help, colleague interest, supervisor help, and supervisor concern. Three types of multilevel mediation models were applied.Overall, workplace reciprocity negatively related to high sickness absence (≥ 10 days mainly independently from health behaviours. Uniquely, colleague interest positively related to smoking (OR = 1.058, 95% CI = 1.019, 1.098 and smoking in turn, positively related to sickness absence (OR = 1.074, 95% CI = 1.047, 1.101. No behavioural pathways could be identified between company-level reciprocity and sickness absence, and company-level health-related behaviours did not mediate the relation between company-level reciprocity and individual sickness absence.These results suggest that both social capital and health behaviours are relevant for employee health, but health behaviours seem not to be the underlying explanatory mechanism between workplace reciprocity and health.

  16. [Duodenal complications of rheumatoid purpura. Endoscopic aspects].

    Science.gov (United States)

    Chapoy, P; Guidon, M J; Louchet, E

    1984-01-01

    The aim of this work was to describe the endoscopic features and clinical outcome of the duodenal complications in anaphylactoid purpura. Over a 3-year period, 20 patients were hospitalized in our unit because of purpura rheumatica. Duodenal complications occurred in 5 cases warranting endoscopic assessment. All patients had bilious vomiting and epigastric pain, constantly associated with low-grade purpuric rash. Plasma factor XIII concentrations were always decreased. The duodenal complication was suspected radiologically in 2 cases when "thumbprint" impressions were seen. Petechiae, oedema and intramural hematoma with superficial erosions were present endoscopically in 3 cases. The lesions were severe and extensive, involving the entire duodenum in 3 cases and the jejunum in one case. In one patient, there was a stricture of the upper part of the second duodenum. Treatment consisted of parenteral nutrition (using a central catheter: 3 cases, or a peripheral vein: 2 cases) and cimetidine (30 mg/kg.bw). The clinical outcome was favorable in 4 patients; the symptoms vanished and the endoscopic lesions were reversible (including the stricture) with restitutio ad integrum after 10 days. The last patient died the 8th day of treatment, 3 days after digestive improvement; the cause of death was probably iatrogenic and related to accidental migration of the central catheter. These results suggest that endoscopic examination should be performed in all patients with anaphylactoid purpura presenting with bilious vomiting. Endoscopy seems to be of great value in deciding if parenteral nutrition is indicated--or not--and perhaps in order to contraindicate the use of steroid therapy in the case of ulcerated hematomas.

  17. Unusual duodenal perforation following endoscopic retrograde cholangiopancreatography

    Directory of Open Access Journals (Sweden)

    Martin Kobborg

    2011-02-01

    Full Text Available Perforation is a known but rare complication to Endoscopic retrograde cholangiopancreatography (ERCP with endoscopic sphincterotomy (ES. Most of the perforations are located in the periampullary area due to ES. This report presents an unusual perforation in the third part of the duodenum following ES. The patient an eigthy-sixt-year-old man underwent ERCP with ES. The patient had Magnetic Resonance Cholangio-pancreatography (MRCP and Computerized Tomography (CT verified cholelithiasis and intra- and extrahepatic cholestasis. The perforation was not found under the ERCP procedure but was clinically revealed when the patient developed pneumoscrotum after the procedure. A CT-scan with oral contrast later confirmed the duodenal perforation.

  18. Duodenal Metastasis of Malignant Pleural Mesothelioma

    Directory of Open Access Journals (Sweden)

    Huang-Chi Chen

    2008-12-01

    Full Text Available Metastatic malignant mesothelioma of the pleura is uncommon at the time of initial diagnosis. The gastrointestinal lumen is rarely found at autopsy in patients with widespread disease. Here, we describe an extremely rare case of isolated duodenal metastasis of sarcomatoid mesothelioma of the pleura in a 73-year-old man, without memory of any direct exposure to asbestos. The possibility of gastrointestinal tract metastasis should be considered in the presence of anemia or positive occult blood test in patients with malignant pleural mesothelioma.

  19. Mechanism of cooperative behaviour in systems of slow and fast molecular motors.

    Science.gov (United States)

    Larson, Adam G; Landahl, Eric C; Rice, Sarah E

    2009-06-28

    Two recent theoretical advances have described cargo transport by multiple identical motors and by multiple oppositely directed, but otherwise identical motors [M. J. Muller, S. Klumpp and R. Lipowsky, Proc. Natl. Acad. Sci. U. S. A., 2008, 105(12), 4609-4614; S. Klumpp and R. Lipowsky, Proc. Natl. Acad. Sci. U. S. A., 2005, 102(48), 17284-17289]. Here, we combine a similar theoretical approach with a simple experiment to describe the behaviour of a system comprised of slow and fast molecular motors having the same directionality. We observed the movement of microtubules by mixtures of slow and fast kinesin motors attached to a glass coverslip in a classic sliding filament assay. The motors are identical, except that the slow ones contain five point mutations that collectively reduce their velocity approximately 15-fold without compromising maximal ATPase activity. Our results indicate that a small fraction of fast motors are able to accelerate the dissociation of slow motors from microtubules. Because of this, a sharp, highly cooperative transition occurs from slow to fast microtubule movement as the relative number of fast motors in the assay is increased. Microtubules move at half-maximal velocity when only 15% of the motors in the assay are fast. Our model indicates that this behaviour depends primarily on the relative motor velocities and the asymmetry between their forward and backward dissociation forces. It weakly depends on the number of motors and their processivity. We predict that movement of cargoes bound to two types of motors having very different velocities will be dominated by one or the other motor. Therefore, cargoes can potentially undergo abrupt changes in movement in response to regulatory mechanisms acting on only a small fraction of motors.

  20. Duodenal adenocarcinoma in a 10-year-old boy

    Directory of Open Access Journals (Sweden)

    Zouari Mohamed

    2014-01-01

    Full Text Available Gastrointestinal malignancies are extremely rare in the paediatric population and duodenal cancers represent an even more unusual entity. It represents 0.3-1% of all gastrointestinal tumours. A case report of a 10-year-old boy with duodenal adenocarcinoma is reported and the difficulties of diagnosing and treating this rare tumour are discussed.

  1. Duodenal adenocarcinoma in a 10-year-old boy.

    Science.gov (United States)

    Mohamed, Zouari; Habib, Bouthour; Rabia, Ben Abdallah; Youssef, Hlel; Riath, Ben Malek; Youssef, Gharbi; Nejib, Kaabar

    2014-01-01

    Gastrointestinal malignancies are extremely rare in the paediatric population and duodenal cancers represent an even more unusual entity. It represents 0.3-1% of all gastrointestinal tumours. A case report of a 10-year-old boy with duodenal adenocarcinoma is reported and the difficulties of diagnosing and treating this rare tumour are discussed.

  2. Duodenal pseudolymphoma: A case report and review of literature

    Institute of Scientific and Technical Information of China (English)

    Yong-Heng Huang; Tian-Zhu Long; Zhi-Yu Xiao; Hua Ye; Yun-Le Wan; Jie Wang

    2011-01-01

    We report a rare case of duodenal pseudolymphoma without any symptoms. The lesion located in front of the head of the pancreas was found accidentally during a medical examination. The findings of computed tomography and positron emission tomography-computed tomography suggested a stromal tumor or malignant lymphoma. Surgical resection was performed. The lesions were pathologically diagnosed as duodenal pseudolymphoma.

  3. The anisotropic mechanical behaviour of electro-spun biodegradable polymer scaffolds: Experimental characterisation and constitutive formulation.

    Science.gov (United States)

    Limbert, Georges; Omar, Rodaina; Krynauw, Hugo; Bezuidenhout, Deon; Franz, Thomas

    2016-01-01

    Electro-spun biodegradable polymer fibrous structures exhibit anisotropic mechanical properties dependent on the degree of fibre alignment. Degradation and mechanical anisotropy need to be captured in a constitutive formulation when computational modelling is used in the development and design optimisation of such scaffolds. Biodegradable polyester-urethane scaffolds were electro-spun and underwent uniaxial tensile testing in and transverse to the direction of predominant fibre alignment before and after in vitro degradation of up to 28 days. A microstructurally-based transversely isotropic hyperelastic continuum constitutive formulation was developed and its parameters were identified from the experimental stress-strain data of the scaffolds at various stages of degradation. During scaffold degradation, maximum stress and strain in circumferential direction decreased from 1.02 ± 0.23 MPa to 0.38 ± 0.004 MPa and from 46 ± 11 % to 12 ± 2 %, respectively. In longitudinal direction, maximum stress and strain decreased from 0.071 ± 0.016 MPa to 0.010 ± 0.007 MPa and from 69 ± 24 % to 8 ± 2 %, respectively. The constitutive parameters were identified for both directions of the non-degraded and degraded scaffold for strain range varying between 0% and 16% with coefficients of determination r(2)>0.871. The six-parameter constitutive formulation proved versatile enough to capture the varying non-linear transversely isotropic behaviour of the fibrous scaffold throughout various stages of degradation.

  4. Microstructure, consolidation and mechanical behaviour of Mg/n-TiC composite

    Directory of Open Access Journals (Sweden)

    N. Vijay Ponraj

    2016-09-01

    Full Text Available In this work, the microstructure, consolidation and mechanical properties of pure magnesium, magnesium based composite containing with different fractions (5, 10, 15 wt% of Titanium carbide nanoparticles (n-TiC were fabricated via powder metallurgy technique. The fabricated composites exhibited homogeneous distribution of TiC with little porosity. Microstructure of the composite and powders was studied using X-ray diffraction, Scanning electron microscope, and Transmission electron microscope. Microstructural characterization of the materials exposed that the accumulation of nanosized titanium carbide reinforcement enhanced the homogenization during mechanical blending. The relative density, compressibility, green compressive strength, sinterability and hardness of the nanocomposites were also examined. The effect of reinforcement on the densification was studied and reported in terms of the relative density and consolidation behaviour of the Magnesium matrix with n-TiC was studied and best compacted fit obtained through the Heckel, Panelli Ambrosio Filho and Ge equations. The compressive strength of the composite significantly increases from 230 MPa to 389 MPa with content of n-TiC and sintering temperature. Experiments have been performed under different conditions of temperature, n-TiC Content, and compacting pressure.

  5. Investigation on effect of fibre hybridization and orientation on mechanical behaviour of natural fibre epoxy composite

    Indian Academy of Sciences (India)

    P KALIAPPAN; R KESAVAN; B VIJAYA RAMNATH

    2017-08-01

    Nowadays bio fibre composites play a vital role by replacing conventional materials used in automotive andaerospace industries owing to their high strength to weight ratio, biodegradability and ease of production. This paper aimsto find the effect of fibre hybridization and orientation on mechanical behaviour of composite fabricated with neem, abacafibres and epoxy resin. Here, three varieties of composites are fabricated namely, composite 1 which consists of abaca fibreand glass fibre, composite 2, which consists of neem fibre and glass fibre, whereas composite 3 consists of abaca, neem fibresand glass fibres. In all the above three varieties, fibres are arranged in three types of orientations namely, horizontal (type I),vertical (type II) and 45$^{\\circ}$ inclination (type III). The result shows that composites made up of abaca and neem fibres withinclined orientation (45$^{\\circ}$) have better mechanical properties when compared with other types of composites. In addition, morphological analysis is carried out using scanning electron microscope to know the fibre distribution, fibre pull out, fibre breakage and crack propagation on tested composites.

  6. Composition dependent mechanical behaviour of S53P4 bioactive glass putty for bone defect grafting.

    Science.gov (United States)

    van Gestel, N A P; Hulsen, D J W; Geurts, J; Hofmann, S; Ito, K; Arts, J J; van Rietbergen, B

    2017-05-01

    To improve the handling properties of S53P4 bioactive glass granules for clinical applications, bioactive glass putty formulations were developed. These formulations contain both granules and a synthetic binder to form an injectable material that is easy to shape. To explore its applicability in load-bearing bone defect grafting, the relation between the putty composition and its mechanical behaviour was assessed in this study. Five putty formulations with variations in synthetic binder and granule content were mechanically tested in confined compression. The results showed that the impaction strains significantly decreased and the residual strains significantly increased with an increasing binder content. The stiffness of all tested formulations was found to be in the same range as the reported stiffness of cancellous bone. The measured creep strains were low and no significant differences between formulations were observed. The stiffness significantly increased when the samples were subjected to a second loading stage. The residual strains calculated from this second loading stage were also significantly different from the first loading stage, showing an increasing difference with an increasing binder content. Since residual strains are detrimental for graft layer stability in load-bearing defects, putty compositions with a low binder content would be most beneficial for confined, load-bearing bone defect grafting.

  7. Retrospective analysis of duodenal injuries: A comprehensive overview

    Directory of Open Access Journals (Sweden)

    Sanjay Pandey

    2011-01-01

    Full Text Available Background/Aim: Duodenal injury is an uncommon finding, accounting for about about 3 - 5% of abdominal trauma, mainly resulting from both penetrating and blunt trauma, and is associated with significant mortality (6 - 25% and morbidity (30 - 60%. Patients and Methods : Retrospective analysis was performed in terms of presentation, management, morbidity and mortality on 14 patients of duodenal injuries out of a total of 172 patients of abdominal trauma attending Subharti Medical College. Results: Epigastric pain (100% along with vomiting (100% is the usual presentation of duodenal injuries in blunt abdominal trauma, especially to the upper abdomen. Computed tomography (CT was diagnostic in all cases. Isolated duodenal injury is a rare finding and the second part is mostly affected. Conclusion: Duodenal injury should always be suspected in blunt upper abdominal trauma, especially in those presenting with epigastric pain and vomiting. Investigation by CT and early surgical intervention in these patients are valuable tools to reduce the morbidity and mortality.

  8. Presentation and Surgical Management of Duodenal Duplication in Adults

    Directory of Open Access Journals (Sweden)

    Caroline C. Jadlowiec

    2015-01-01

    Full Text Available Duodenal duplications in adults are exceedingly rare and their diagnosis remains difficult as symptoms are largely nonspecific. Clinical presentations include pancreatitis, biliary obstruction, gastrointestinal bleeding from ectopic gastric mucosa, and malignancy. A case of duodenal duplication in a 59-year-old female is presented, and her treatment course is reviewed with description of combined surgical and endoscopic approach to repair, along with a review of historic and current recommendations for management. Traditionally, gastrointestinal duplications have been treated with surgical resection; however, for duodenal duplications, the anatomic proximity to the biliopancreatic ampulla makes surgical management challenging. Recently, advances in endoscopy have improved the clinical success of cystic intraluminal duodenal duplications. Despite these advances, surgical resection is still recommended for extraluminal tubular duplications although combined techniques may be necessary for long tubular duplications. For duodenal duplications, a combined approach of partial excision combined with mucosal stripping may offer advantage.

  9. High CO₂ and marine animal behaviour: potential mechanisms and ecological consequences.

    Science.gov (United States)

    Briffa, Mark; de la Haye, Kate; Munday, Philip L

    2012-08-01

    Exposure to pollution and environmental change can alter the behaviour of aquatic animals and here we review recent evidence that exposure to elevated CO₂ and reduced sea water pH alters the behaviour of tropical reef fish and hermit crabs. Three main routes through which behaviour might be altered are discussed; elevated metabolic load, 'info-disruption' and avoidance behaviour away from polluted locations. There is clear experimental evidence that exposure to high CO₂ disrupts the ability to find settlement sites and shelters, the ability to detect predators and the ability to detect prey and food. In marine vertebrates and marine crustaceans behavioural change appears to occur via info-disruption. In hermit crabs and other crustaceans impairment of performance capacities might also play a role. We discuss the implications for such behavioural changes in terms of potential impacts at the levels of population health and ecosystem services, and consider future directions for research.

  10. Physico-mechanical and dissolution behaviours of ibuprofen crystals crystallized in the presence of various additives

    Directory of Open Access Journals (Sweden)

    A Nokhodchi

    2010-06-01

    Full Text Available "n  "n Background and the purpose of the study: The success of any direct-tableting procedure is strongly affected by the quality of the crystals used in the process. Ibuprofen is a poorly compactible drug with a high tendency for capping. In order to use ibuprofen in direct compression formulations, physico-mechanical properties of ibuprofen should be improved considerably. The aim of the present investigation was to employ crystallization techniques in order to improve the physico-mechanical properties of ibuprofen for direct compression. "nMethods:The experimental methods involved the preparation of ibuprofen crystals by solvent change technique. Ibuprofen was dissolved in ethanol and crystallized out with water in the absence or presence of various hydrophilic additives (PEG 6000, 8000, Brij 98P and polyvinyl alcohol 22000, PVA 22000 with different concentrations. The physico-mechanical properties of the ibuprofen crystals were studied in terms of flow, density, tensile strength and dissolution behaviour. Morphology of ibuprofen crystals was studied by scanning electron microscopic (SEM. Solid state of the recrystallized particles was also investigated using differential scanning calorimeter (DSC and FT-IR. "nResults:Ibuprofen samples crystallized in the presence of PEG 6000 and 8000 and PVA showed remarkable increase in the tensile strengths of the directly compressed tablets, while some other additives, i.e. Brij 98P did not produce improved ibuprofen crystals. Ibuprofen powders made from particles obtained in the presence of PVA and Brij 98P showed similar dissolution profiles to the commercial ibuprofen particles. DSC and FT-IR results ruled out any significant interaction between ibuprofen and additives except for the samples crystallized in the presence of PEG 8000. Conclusion:The crystal habit of ibuprofen can be altered successfully by the crystallization technique which was developed in this study. The crystals developed in the

  11. Effect of hydrogen on the mechanical behaviour of carbon-alloyed Fe3Al-based iron aluminides

    Indian Academy of Sciences (India)

    M Sen; R Balasubramaniam

    2002-06-01

    The effect of hydrogen on the mechanical behaviour of two carbon-alloyed iron aluminides was studied. Weakening of some carbide–metal interfaces in the presence of hydrogen was indicated. The effect of cathodic hydrogen charging on the microstructure has also been addressed.

  12. Models of the behaviour of (thermally stressed) microbial spores in foods: Tools to study mechanisms of damage and repair

    NARCIS (Netherlands)

    ter Beek, A.; Hornstra, L.M.; Pandey, R.; Kallemeijn, W.W.; Smelt, J.P.P.M.; Manders, E.M.M.; Brul, S.

    2011-01-01

    The ‘Omics’ revolution has brought a wealth of new mechanistic insights in many fields of biology. It offers options to base predictions of microbial behaviour on mechanistic insight. As the cellular mechanisms involved often turn out to be highly intertwined it is crucial that model development aim

  13. Dispersebility degree influence of glass fibre E in the mechanical behaviour and workability of plaster

    Directory of Open Access Journals (Sweden)

    del Río Merino, M.

    2001-03-01

    Full Text Available Although there are many research studies about plaster strengthened with glass fibre E in Spain, there are no publications which advise the users (plasterers, manufacturers of prefabricated blocks or suspended ceilings, etc about the most appropriated types of fibre E in respect to its dispersebility degree in the matrix, its lengths, the percentage, or even the type of strengthening, etc. The study of the use of this strengthener is to achieve an improvement in the mechanical behaviour of plaster as well as better conditions in the paste workability. The company Vetrotex, with the technical personnel and together with the Department of Architectural Constructions and their control (E. U. A. T. M. have started a serious research on plaster strengthened with E fibre. Conclusions shown in this first article are about the influence of the dispersebility degree of glass fibres in the mechanical behaviour of the compound as well as its workability. The degree of dispersibility of the fibres in the matrix is closely related to the type of covering used in the production of the strengthening fibres.

    Aunque existen muchos trabajos de investigación sobre el refuerzo del yeso con fibra de vidrio E en España, no hay publicaciones que asesoren a los usuarios (aplicadores de yeso proyectado, fabricantes de prefabricados como bloques o falsos techos, etc. de los tipos défibra de vidrio E más adecuados, atendiendo a su grado de dispersabilidad en la matriz, las longitudes, el porcentaje, e incluso el tipo de refuerzo, etc., a efectos de conseguir un aumento del comportamiento mecánico del yeso/escayola y unas ciertas condiciones de trabajabilidad de la pasta. La empresa Vetrotex, a través de sus técnicos y en colaboración con el Departamento de Construcciones Arquitectónicas y su control (E. U. A. T. M., decide acometer un estudio en profundidad de la escayola reforzada con fibra de vidrio E. En este primer artículo se presentan las

  14. Behavioural alterations from exposure to Cu, phenanthrene, and Cu-phenanthrene mixtures: linking behaviour to acute toxic mechanisms in the aquatic amphipod, Hyalella azteca.

    Science.gov (United States)

    Gauthier, Patrick T; Norwood, Warren P; Prepas, Ellie E; Pyle, Greg G

    2016-01-01

    Phenanthrene (PHE) and Cu are two contaminants commonly co-occurring in marine and freshwater environments. Mixtures of PHE and Cu have been reported to induce more-than-additive lethality in the amphipod, Hyalella azteca, a keystone aquatic invertebrate, yet little is understood regarding the interactive toxic mechanisms that mediate more-than-additive toxicity. Understanding the interactions among toxic mechanisms among Cu and PHE will allow for better predictive power in assessing the ecological risks of Cu-PHE mixtures in aquatic environments. Here we use behavioural impairment to help understand the toxic mechanisms of Cu, PHE, and Cu-PHE mixture toxicity in the aquatic amphipod crustacean, Hyalella azteca. Our principal objective was to link alterations in activity and ventilation with respiratory rates, oxidative stress, and neurotoxicity in adult H. azteca. Adult amphipods were used for all toxicity tests. Amphipods were tested at sublethal exposures of 91.8- and 195-μgL(-1) Cu and PHE, respectively, and a Cu-PHE mixture at the same concentrations for 24h. Neurotoxicity was measured as acetylcholinesterase (AChE) activity, where malathion was used as a positive control. Oxidative stress was measured as reactive oxygen species (ROS) production. Phenanthrene-exposed amphipods exhibited severe behavioural impairment, being hyperstimulated to the extent that they were incapable of coordinating muscle movements. In addition, respiration and AChE activity in PHE-exposed amphipods were increased and reduced by 51% and 23% respectively. However, ROS did not increase following exposure to phenanthrene. In contrast, Cu had no effect on amphipod behaviour, respiration or AChE activity, but did lead to an increase in ROS. However, co-exposure to Cu antagonized the PHE-induced reduction in ventilation and negated any increase in respiration. The results suggest that PHE acts like an organophosphate pesticide (e.g., malathion) in H. azteca following 24h sublethal

  15. Mechanical behaviour of glass fiber weaven UD/high fluidity PA-based polymers for automotive applications

    Science.gov (United States)

    Dana, Hossein Ramezani; Gomina, Moussa; Bréard, Joël; Orange, Gilles

    2016-10-01

    This experimental work addresses the mechanical behavior of weaven UD glass fiber-thermoplastic composites designed for layered materials to be used in the automotive industry. The investigation was implemented in terms of the formulation of the PA66-based thermoplastic resins, the architecture of the fibrous reinforcement (warp spacer) and the glass fiber content. Longitudinal and transverse tensile tests results demonstrate the excellent mechanical behavior of these composites, which correlates with the rheological/permeability properties and wettability behaviour.

  16. Retrogression, reaging, and mechanical behaviour of a 1441 Al-Li-Cu-Mg-Zr alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, K.S. [Dept. of Metallurgical and Materials Engineering, National Inst. of Tech., Warangal (India); Das, K.; Chatterjee, U.K. [Dept. of Metallurgical and Materials Engineering, Indian Inst. of Tech., Kharagpur (India)

    2005-12-01

    A 1441 Al-Li-Cu-Mg-Zr alloy was subjected to retrogression treatment and the retrogressed states were immediately reaged to various tempers. Hardness measurement, tensile testing, and SEM fractography have been carried out to conventional peak-aged, retrogressed, retrogressed and reaged (RRA), and over-aged tempers of the alloy. Retrogression treatment applied to peak-aged tempered alloys resulted in a decrease in hardness and tensile strength, an increase of ductility, and a serration phenomenon in the plastic region. These are primarily due to the dissolution of matrix strengthening {delta}' precipitates into solid solution upon retrogression treatment. Retrogressed states have been reaged to various under-, peak-, and over-aged tempers. Reaging the retrogressed state to peak-aged temper has resulted in attaining the original peak-aged strength and ductility value. SEM fractography study has been carried out and fracture surfaces exhibited predominantly intergranular fracture in presence of few dimples. TEM and DSC studies have been carried out to observe the microstructural changes upon RRA treatment and to explain the mechanical behaviour of the alloy. (orig.)

  17. Computational modelling of cell chain migration reveals mechanisms that sustain follow-the-leader behaviour.

    Science.gov (United States)

    Wynn, Michelle L; Kulesa, Paul M; Schnell, Santiago

    2012-07-07

    Follow-the-leader chain migration is a striking cell migratory behaviour observed during vertebrate development, adult neurogenesis and cancer metastasis. Although cell-cell contact and extracellular matrix (ECM) cues have been proposed to promote this phenomenon, mechanisms that underlie chain migration persistence remain unclear. Here, we developed a quantitative agent-based modelling framework to test mechanistic hypotheses of chain migration persistence. We defined chain migration and its persistence based on evidence from the highly migratory neural crest model system, where cells within a chain extend and retract filopodia in short-lived cell contacts and move together as a collective. In our agent-based simulations, we began with a set of agents arranged as a chain and systematically probed the influence of model parameters to identify factors critical to the maintenance of the chain migration pattern. We discovered that chain migration persistence requires a high degree of directional bias in both lead and follower cells towards the target. Chain migration persistence was also promoted when lead cells maintained cell contact with followers, but not vice-versa. Finally, providing a path of least resistance in the ECM was not sufficient alone to drive chain persistence. Our results indicate that chain migration persistence depends on the interplay of directional cell movement and biased cell-cell contact.

  18. Growth behaviour and mechanical properties of PLL/HA multilayer films studied by AFM.

    Science.gov (United States)

    Uzüm, Cagri; Hellwig, Johannes; Madaboosi, Narayanan; Volodkin, Dmitry; von Klitzing, Regine

    2012-01-01

    Scanning- and colloidal-probe atomic force microscopy were used to study the mechanical properties of poly(L-lysine)/hyaluronan (PLL/HA)(n) films as a function of indentation velocity and the number of polymer deposition steps n. The film thickness was determined by two independent AFM-based methods: scratch-and-scan and newly developed full-indentation. The advantages and disadvantages of both methods are highlighted, and error minimization techniques in elasticity measurements are addressed. It was found that the film thickness increases linearly with the bilayer number n, ranging between 400 and 7500 nm for n = 12 and 96, respectively. The apparent Young's modulus E ranges between 15 and 40 kPa and does not depend on the indenter size or the film bilayer number n. Stress relaxation measurements show that PLL/HA films have a viscoelastic behaviour, regardless of their thickness. If indentation is performed several times at the same lateral position on the film, a viscous/plastic deformation takes place.

  19. The structural and mechanical behaviours of Boron-doped ZnO nanostructures

    Science.gov (United States)

    Senol, Abdulkadir; Demirozu Senol, Sevim; Ozturk, Ozgur; Asikuzun, Elif; Tasci, Ahmet Tolga; Terzioglu, Cabir

    2015-03-01

    Undoped and Boron (B)-doped Zinc Oxide (ZnO) nanopowders were synthesized by Hydrothermal method. The structural and mechanical behaviours of B doped ZnO (Zn1-xBx O, x =0, 0.05, 0.07, 0.11) were systematically examined. The crystal structure, phases, sizes and microstructure of Zn1-xBx O powder samples characterized by using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Microhardness values of all B doped ZnO powders were measured with different loads (0.245, 0.490, 0.980, 1.960 ve 2.940 N) using a digital Vickers microhardness tester. The experimental microhardness data were used to determine elastic modules, yield strength, and fracture toughness value of the samples. Additionally, the experimental results were analyzed using the various theoretical models namely, Kick's Law, Elastic/Plastic Deformation (EPD) models, Proportional Specimen Resistance (PSR), and Hays-Kendall (HK) approach. The Vickers microhardness measurements revealed that hardness of Zn1-xBx O powder samples increased with B doping. This research partially supported by Abant Izzet Baysal University Scientific Research Projects Coordination Department under the Grant No. BAP-2013.03.02.609.

  20. Computer Simulation of the Mechanical Behaviour of Implanted Biodegradable Stents in a Remodelling Artery

    Science.gov (United States)

    Boland, Enda L.; Grogan, James A.; Conway, Claire; McHugh, Peter E.

    2016-04-01

    Coronary stents have revolutionised the treatment of coronary artery disease. While coronary artery stenting is now relatively mature, significant scientific and technological challenges still remain. One of the most fertile technological growth areas is biodegradable stents; here, there is the possibility to generate stents that will break down in the body once the initial necessary scaffolding period is past (6-12 months) (Grogan et al. in Acta Biomater 7:3523, 2011) and when the artery has remodelled (including the formation of neo-intima). A stent angioplasty computational test-bed has been developed by the authors, based on the Abaqus software (DS-SIMULIA, USA), capable of simulating stent tracking, balloon expansion, recoil and in vivo loading in a atherosclerotic artery model. Additionally, a surface corrosion model to simulate uniform and pitting corrosion of biodegradable stents and a representation of the active response of the arterial tissue following stent implantation, i.e. neointimal remodelling, has been developed. The arterial neointimal remodelling simulations with biodegradable stent corrosion demonstrate that the development of new arterial tissue around the stent struts has a substantial effect on the mechanical behaviour of degrading stents.

  1. Comparison of the Mechanical Behaviour of Selected Oilseeds under Compression Loading

    Directory of Open Access Journals (Sweden)

    David HERAK

    2012-11-01

    Full Text Available The present study provides information about the comparison of mechanical behaviour of selected oil bearing crops namely rapeseeds (Brassica napus L., sunflower seeds (Helianthus annus L. and jatropha seeds (Jatropha curcas L. under compression loading. In this research, the compression device ZDM 50 with a chart recorder and a pressing vessel with diameter 100 mm were used to determine the relationship between the magnitude of the pressing force and deformation characteristics of the oilseed crops pressed at initial height 80 mm. From the compression test, the amounts of true deformation, maximal deformation energy and compressive force of the pressed samples were calculated and also mathematical equations describing the limit deformation, maximal deformation ratio, energy ratio and oil point deformation ratio were determined. The oil point position on the deformation curve, that is, the first leakage of oil from the pressing vessel of the various oilseeds was determined and compared. Based on the measured amounts rapeseeds achieved the highest values followed by jatropha seed and then sunflower seed. The amount of deformation energy required for the seed deformation gives the indication the amount of energy needed for obtaining the oil from the seed. It was found that the measured amounts as well as the oil point position on the force-deformation curve of the pressed samples showed varying results due to the seeds physical and inherent characteristics.

  2. The simulation of mechanical and thermal behaviour of CANDU fuel channel in thermal transient conditions

    Energy Technology Data Exchange (ETDEWEB)

    Maria Mihalache; Vasile Radu; Margarit Pavelescu [INR-Pitesti (Romania)

    2006-07-01

    Full text of publication follows: In certain LOCA conditions in a CANDU-6 NPP (high temperature and high pressure), the pressure tube of fuel channel may balloon by creep into contact with the calandria tube. After the contact moment, a radial heat transfer to the moderator through the contact area is occurring. When the temperature of calandria tube walls increases, the contact area is drying and the heat transfer becomes inefficiently. Thus, the fuel channel could lose its integrity. This paper presents a computer code, DELOCA, developed in INR-Pitesti, which simulate the transient thermo-mechanical behaviour of CANDU fuel channel before and after contact. The code contains few models: alloy creep, heat transfer by conduction through the cylindrical walls, channel failure criteria and calculus of heat transfer at the calandria tube - moderator interface. This code evaluates the contact, dry-out and channel failure moments. In this paper, the simulation results calculated at different temperature increasing rates are presented. Also, the contact moments in different axial-circumferential segments for the postulated accident Rupture of Inlet Header of 5% (RIH5%) were presented. The simulations predict the strain and stress state in the circumferential-axial elements. The input data was furnished by the Cathena thermo-hydraulic code. Also, the results of RIH5% accident are presented in comparison with the results of same simulation with Cathena Code. (authors)

  3. Dynamic Mechanical Behaviour of Ultra-high Performance Fiber Reinforced Concretes

    Institute of Scientific and Technical Information of China (English)

    LAI Jianzhong; SUN Wei

    2008-01-01

    Ultra-high performance fiber reinforced concretes (UHPFRC) were prepared by replacing 60% of cement with ultra-fine industrial waste powder.The dynamic mechanical behaviour of UHPFRC with different fiber volume fraction was researched on repeated compressive impact in four kinds of impact modes through split Hopkinson pressure bar (SHPB).The experimental results show that the peak stress and elastic modulus decrease and the strain rate and peak strain increase gradually with the increasing of impact times.The initial material damage increases and the peak stress of the specimen decreases from the second impact with the increasing of the initial incident wave.Standard strength on repeated impact is defined to compare the ability of resistance against repeated impact among different materials.The rate of reduction of standard strength is decreased by fiber reinforcement under repeated impact.The material damage is reduced and the ability of repeated impact resistance of UHPFRC is improved with the increasing of fiber volume fraction.

  4. Dynamic mechanical behaviour and dislocation substructure evolution of Inconel 718 over wide temperature range

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Woei-Shyan, E-mail: wslee@mail.ncku.edu.tw [Department of Mechanical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Lin, Chi-Feng [National Center for High-Performance Computing, Hsin-Shi Tainan County 744, Taiwan (China); Chen, Tao-Hsing [Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 807, Taiwan (China); Chen, Hong-Wei [Department of Mechanical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China)

    2011-07-25

    A compressive split-Hopkinson pressure bar and transmission electron microscope (TEM) are used to investigate the mechanical behaviour and microstructural evolution of Inconel 718 at strain rates ranging from 1000 to 5000 s{sup -1} and temperatures between -150 and 550 deg. C. The results show that the flow stress increases with an increasing strain rate or a reducing temperature. The strain rate effect is particularly pronounced at strain rates greater than 3000 s{sup -1} and a deformation temperature of -150 deg. C. A significant thermal softening effect occurs at temperatures between -150 and 25 deg. C. The microstructural observations reveal that the strengthening effect in deformed Inconel 718 alloy is a result primarily of dislocation multiplication. The dislocation density increases with increasing strain rate, but decreases with increasing temperature. By contrast, the dislocation cell size decreases with increasing strain rate, but increases with increasing temperature. It is shown that the correlation between the flow stress, the dislocation density and the dislocation cell size is well described by the Bailey-Hirsch constitutive equations.

  5. Aging Behaviour and Mechanical Performance of 18-Ni 300 Steel Processed by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Riccardo Casati

    2016-09-01

    Full Text Available An 18-Ni 300 grade maraging steel was processed by selective laser melting and an investigation was carried out on microstructural and mechanical behaviour as a function of aging condition. Owing to the rapid cooling rate, the as-built alloy featured a full potential for precipitate strengthening, without the need of a solution treatment prior to aging. The amount of reversed austenite found in the microstructure increased after aging and revealed to depend on aging temperature and time. Similarly to the corresponding wrought counterpart, also in the selective laser-melted 18-Ni 300 alloy, aging promoted a dramatic increase in strength with respect to the as-built condition and a drop in tensile ductility. No systematic changes were found in tensile properties as a function of measured amount of austenite. It is proposed that the submicrometric structure and the phase distribution inherited by the rapid solidification condition brought by selective laser melting are such that changes in tensile strength and ductility are mainly governed by the effects brought by the strengthening precipitates, whereas the concurrent reversion of the γ-Fe phase in different amounts seems to play a minor role.

  6. Effect of Calcium Sulphate Nanoparticles on Fusion, Mechanical and Thermal Behaviour Polyvinyl Chloride (pvc)

    Science.gov (United States)

    Patil, C. B.; Shisode, P. S.; Kapadi, U. R.; Hundiwale, D. G.; Mahulikar, P. P.

    Calcium Sulphate [CaSO4] was synthesized by in-situ deposition technique and its nano size (60 to 100 nm) was confirmed by Transmission Electron Microscopy (TEM). Composites of the filler CaSO4 (micro and nano) and the matrix poly (vinyl chloride) (PVC) were prepared with different filler loading (0-5 wt. %) by melt mixing. The Brabender torque rheometer equipped with an internal mixer was used for preparation and evaluation of fusion behaviour of composites of different formulations. The effect of nano and micro-CaSO4 content on the structure and properties of composites was studied. The nanostructures and dispersion were studied by wide angle X-ray diffraction (WAXD) and scanning electron microscopy (SEM). The mechanical and thermal properties of PVC/ micro and nano-CaSO4 composites were characterized using Universal Testing Machine (UTM) and Thermo Gravimetric Analyzer (TGA). From the results of WAXD and SEM the flocculation of CaSO4 nanoparticles were observed on the surfaces of PVC matrix. The thermal analysis results showed that the first thermal degradation onset (T onset) of PVC/nano-CaSO4 composites for 1 wt. % of filler were higher as compared with corresponding microcomposites and pristine PVC. However, the tensile strength was decreasing with increasing filler content while, it shows increment in magnitude at 1 and 2 wt. % of nano-CaSO4 as compared with corresponding micro-CaSO4 as well as pristine PVC.

  7. Quasi-morphine abstinence behaviour GABA-ergic mechanisms and their localization

    NARCIS (Netherlands)

    J.W. van der Laan

    1981-01-01

    textabstractDi-n-propylacetate (DPA), generally known to be an anti-epileptic drug, induces a behavioural syndrome in rats resembling morphine abstinence behaviour, which is called, therefore, quasi-morphine abstinence beh~viour. An increase in GABA-ergic activity is probably responsible for this be

  8. The dynamical integrity concept for interpreting/ predicting experimental behaviour: from macro- to nano-mechanics.

    Science.gov (United States)

    Lenci, Stefano; Rega, Giuseppe; Ruzziconi, Laura

    2013-06-28

    The dynamical integrity, a new concept proposed by J.M.T. Thompson, and developed by the authors, is used to interpret experimental results. After reviewing the main issues involved in this analysis, including the proposal of a new integrity measure able to capture in an easy way the safe part of basins, attention is dedicated to two experiments, a rotating pendulum and a micro-electro-mechanical system, where the theoretical predictions are not fulfilled. These mechanical systems, the former at the macro-scale and the latter at the micro-scale, permit a comparative analysis of different mechanical and dynamical behaviours. The fact that in both cases the dynamical integrity permits one to justify the difference between experimental and theoretical results, which is the main achievement of this paper, shows the effectiveness of this new approach and suggests its use in practical situations. The men of experiment are like the ant, they only collect and use; the reasoners resemble spiders, who make cobwebs out of their own substance. But the bee takes the middle course: it gathers its material from the flowers of the garden and field, but transforms and digests it by a power of its own. Not unlike this is the true business of philosophy (science); for it neither relies solely or chiefly on the powers of the mind, nor does it take the matter which it gathers from natural history and mechanical experiments and lay up in the memory whole, as it finds it, but lays it up in the understanding altered and digested. Therefore, from a closer and purer league between these two faculties, the experimental and the rational (such as has never been made), much may be hoped. (Francis Bacon 1561-1626) But are we sure of our observational facts? Scientific men are rather fond of saying pontifically that one ought to be quite sure of one's observational facts before embarking on theory. Fortunately those who give this advice do not practice what they preach. Observation and theory get

  9. Mechanical behaviour of alkali-activated blast furnace slag-activated metakaolin blended pastes. Statistical study

    Directory of Open Access Journals (Sweden)

    Higuera, I.

    2012-06-01

    Full Text Available The study and development of alternative, more ecoefficient binders than portland cement are attracting a good deal of scientific and technological interest. Binders obtained from the chemical interaction between calcium silico-aluminous materials and highly alkaline solutions are one of several types of such possible cements. The present paper discusses the mechanical behaviour and mineralogical composition of blended pastes made from NaOH-activated vitreous blast furnace slag and metakaolin. The aim of the study was to determine how parameters such as the slag/metakaolin ratio, activating solution concentration and curing temperature affect strength development in these binders. A statistical study was conducted to establish the impact of each variable and model strength behaviour in these alkaline cements. The conclusion drawn is that activator concentration and the slag/metakaolin ratio are both determinant parameters.

    El estudio y desarrollo de cementos alternativos y más eco-eficientes que el cemento Portland es un tema de gran impacto a nivel científico y tecnológico. Entre esos posibles cementos se encuentran los cementos alcalinos que son materiales conglomerantes obtenidos por la interacción química de materiales silico-aluminosos cálcicos y disoluciones fuertemente alcalinas. En el presente trabajo se estudia el comportamiento mecánico y la composición mineralógica de mezclas de escoria vítrea de horno alto y metacaolín activadas alcalinamente con disoluciones de NaOH. El objetivo de este estudio es conocer cómo afectan parámetros tales como la relación escoria/metacaolín, la concentración de la disolución activadora y la temperatura de curado, al desarrollo resistente de las mezclas. A través del estudio estadístico realizado se ha podido establecer la influencia de cada variable y modelizar el comportamiento resistente de estos cementos alcalinos. Se concluye que la concentración del activador y la relaci

  10. Duodenal obstruction due to a preduodenal portal vein

    Directory of Open Access Journals (Sweden)

    MNC Vilakazi

    2014-01-01

    Full Text Available An infant presented with clinical signs and symptoms suggestive of a pyloric stenosis. On abdominal ultrasound, pyloric stenosis was excluded, and other causes for proximal duodenal obstruction, such as a duodenal web or annular pancreas, were suspected. At surgery, the cause was found to be due to an anterior portal vein or preduodenal portal vein, compressing the duodenum. There were no associated findings such as midgut malrotation, duodenal web and congenital anomalies. The treatment was a diamond-shaped duodeno-duodenostomy anterior to the portal vein. The patient improved after surgery.

  11. Duodenal Bleeding from Metastatic Renal Cell Carcinoma

    Science.gov (United States)

    Rustagi, Tarun; Rangasamy, Priya; Versland, Mark

    2011-01-01

    Massive upper gastrointestinal bleeding due to malignancy is relatively uncommon and the duodenum is the least frequently involved site. Duodenal metastasis is rare in renal cell carcinoma (RCC) and early detection, especially in case of a solitary mass, helps in planning further therapy. We report a case of intractable upper gastrointestinal bleeding from metastatic RCC to the duodenum. The patient presented with melena and anemia, 13 years after nephrectomy for RCC. On esophagogastroduodenoscopy, a submucosal mass was noted in the duodenum, biopsies of which revealed metastatic RCC. In conclusion, metastasis from RCC should be considered in nephrectomized patients presenting with gastrointestinal symptoms and a complete evaluation, especially endoscopic examination followed by biopsy, is suggested. PMID:21577373

  12. Duodenal Bleeding from Metastatic Renal Cell Carcinoma

    Directory of Open Access Journals (Sweden)

    Tarun Rustagi

    2011-04-01

    Full Text Available Massive upper gastrointestinal bleeding due to malignancy is relatively uncommon and the duodenum is the least frequently involved site. Duodenal metastasis is rare in renal cell carcinoma (RCC and early detection, especially in case of a solitary mass, helps in planning further therapy. We report a case of intractable upper gastrointestinal bleeding from metastatic RCC to the duodenum. The patient presented with melena and anemia, 13 years after nephrectomy for RCC. On esophagogastroduodenoscopy, a submucosal mass was noted in the duodenum, biopsies of which revealed metastatic RCC. In conclusion, metastasis from RCC should be considered in nephrectomized patients presenting with gastrointestinal symptoms and a complete evaluation, especially endoscopic examination followed by biopsy, is suggested.

  13. Duodenal bleeding from metastatic renal cell carcinoma.

    Science.gov (United States)

    Rustagi, Tarun; Rangasamy, Priya; Versland, Mark

    2011-04-20

    Massive upper gastrointestinal bleeding due to malignancy is relatively uncommon and the duodenum is the least frequently involved site. Duodenal metastasis is rare in renal cell carcinoma (RCC) and early detection, especially in case of a solitary mass, helps in planning further therapy. We report a case of intractable upper gastrointestinal bleeding from metastatic RCC to the duodenum. The patient presented with melena and anemia, 13 years after nephrectomy for RCC. On esophagogastroduodenoscopy, a submucosal mass was noted in the duodenum, biopsies of which revealed metastatic RCC. In conclusion, metastasis from RCC should be considered in nephrectomized patients presenting with gastrointestinal symptoms and a complete evaluation, especially endoscopic examination followed by biopsy, is suggested.

  14. Thyroid Storm Precipitated by Duodenal Ulcer Perforation

    Directory of Open Access Journals (Sweden)

    Shoko Natsuda

    2015-01-01

    Full Text Available Thyroid storm is a rare and life-threatening complication of thyrotoxicosis that requires prompt treatment. Thyroid storm is also known to be associated with precipitating events. The simultaneous treatment of thyroid storm and its precipitant, when they are recognized, in a patient is recommended; otherwise such disorders, including thyroid storm, can exacerbate each other. Here we report the case of a thyroid storm patient (a 55-year-old Japanese male complicated with a perforated duodenal ulcer. The patient was successfully treated with intensive treatment for thyroid storm and a prompt operation. Although it is believed that peptic ulcer rarely coexists with hyperthyroidism, among patients with thyroid storm, perforation of a peptic ulcer has been reported as one of the causes of fatal outcome. We determined that surgical intervention was required in this patient, reported despite ongoing severe thyrotoxicosis, and reported herein a successful outcome.

  15. Ice shedding from overhead electrical lines by mechanical breaking : a ductile model for viscoplastic behaviour of atmospheric ice

    Energy Technology Data Exchange (ETDEWEB)

    Eskandarian, M.

    2005-07-01

    The mechanical characteristics of power line components need improvement in order to avoid power failures during severe ice storms. Atmospheric icing of overhead power lines creates electrical and mechanical problems in the transmission network. The successful development of anti-icing and de-icing techniques requires good knowledge of the adherence and bulk strength characteristics of atmospheric ice. This study presented a model for viscoplastic behaviour of porous atmospheric ice in the ductile region. The model was then modified to consider the effects of cracking activities to predict the material behaviour in transition and brittle regions. The following general methodologies were followed in this research for describing the ductile behaviour of porous atmospheric ice: instantaneous elastic strain; delayed viscoelastic strain; and, permanent plastic strain. The scientific contributions of this study include a classification of atmospheric ice structure on power lines on the basis of its grain shape and c-axis orientation. This thesis also presented 3 computer codes in Maple Mathematical Program for determining the elastic moduli of various types of freshwater ice; a poroelastic model for modifying the elastic moduli of porous atmospheric ice; a cap-model plasticity for various types of porous atmospheric ice; new freshwater ice yield envelopes in ductile regions that take porosity into account by means of an elliptical moving cap; and a newly developed user-defined material subroutine for viscoplastic behaviour of atmospheric ice in ductile region including the poroelastic, viscoelastic, and cap-model plasticity.

  16. Mechanisms of zinc incorporation in aluminosilicate crystalline structures and the leaching behaviour of product phases.

    Science.gov (United States)

    Tang, Yuanyuan; Shih, Kaimin

    2015-01-01

    This study quantitatively evaluates a waste-to-resource strategy of blending zinc-laden sludge and clay material for low-cost ceramic products. Using ZnO as the simulated zinc-laden sludge to sinter with kaolinite, both zinc aluminate spinel (ZnAl₂O₄) and willemite (Zn₂SiO₄) phases were formed during the sintering process. To analyse the details of zinc incorporation reactions, γ-Al₂O₃and quartz were further used as precursors to observe ZnAl₂O₄and Zn₂SiO₄formations. By firing the ZnO mixtures and their corresponding precursors at 750-1350°C for 3 h, the efficiency of zinc transformation was determined through Rietveld refinement analyses of X-ray diffraction data. The results also show different incorporation behaviour for kaolinite and mullite precursors during the formation of ZnAl2O₄and Zn2SiO₄in the system. In addition, with a competitive formation between ZnAl₂O₄and Zn₂SiO₄, the ZnAl₂O₄spinel phase is predominant at temperatures higher than 1050°C. This study used a prolonged leaching test modified from the US Environmental Protection Agency's toxicity characteristic leaching procedure to evaluate ZnO, ZnAl₂O₄, and Zn₂SiO₄product phases. The zinc concentrations in ZnO and Zn₂SiO₄leachates were about two orders of magnitude higher than that of ZnAl₂O₄ leachate at the end of the experiment, indicating that ZnAl₂O₄formation is the preferred stabilization mechanism for incorporating zinc in ceramic products.

  17. Mechanical behaviour of steel fibre-reinforced alkali activated slag concrete

    Directory of Open Access Journals (Sweden)

    Puertas, F.

    2009-03-01

    Full Text Available This study addressed the mechanical behaviour of a steel fibre-reinforced alternative concrete made from waterglass (Na2SiO3.nH2O+NaOH- activated Colombian blast furnace slag. The mixes studied were prepared with 400 kg of cement and the fibres were added in proportions of 40 and 120 kg per cubic metre of concrete. 7-, 14- and 28-day concrete was tested for compressive, splitting tensile and flexural strength. The results obtained showed that adding steel fibre to alkaline concrete lowered early age compressive strength, and that this decline was more intense with rising volumes of steel. Flexural and splitting tensile strength grew, however, enhancing the toughness of the material. As a general rule, the mechanical strength of the plain and fibre-reinforced alkaline concretes studied was higher than exhibited by conventional ordinary Portland cement concrete prepared with similar proportions of cement and fibre.En este estudio se investigó el comportamiento mecánico de hormigones alternativos reforzados con fibras de acero, basados en una escoria siderúrgica colombiana activada alcalinamente con waterglass (Na2SiO3.nH2O+NaOH. Las mezclas en estudio fueron preparadas con 400 kg de cemento y las fibras fueron incorporadas en proporciones de 40 kg y 120 kg por metro cúbico de hormigón, respectivamente. Se evaluó el comportamiento mecánico de los hormigones frente a esfuerzos de compresión, tracción indirecta y flexión a edades de curado de 7, 14 y 28 días. Los resultados obtenidos indican que la incorporación de fibras de acero en los hormigones alcalinos reduce la resistencia a la compresión a edades tempranas siendo superior la pérdida de resistencia a mayores volúmenes de fibra incorporados, mientras que la resistencia a la flexión y tracción indirecta se incrementan significativamente, mejorando la tenacidad del material. En términos generales, es posible concluir que el comportamiento mecánico exhibido por los hormigones

  18. Mechanical behaviour of the Krafla geothermal reservoir: Insight into an active magmatic hydrothermal system

    Science.gov (United States)

    Eggertsson, Guðjón H.; Lavallée, Yan; Kendrick, Jackie E.

    2017-04-01

    Krafla volcano, located in North-East Iceland, holds an active magmatic hydrothermal system. Since 1978, this system has been exploited for geothermal energy. Today it is exploited by Landsvirkjun National Power of Iceland and the system is generating 60 MWg from 18 wells, tapping into fluids at 200-300°C. In order to meet further demands of environmentally sustainable energy, Landsvirkjun aims to drill deeper and source fluids in the super-heated, super high-enthalpy system which resides deeper (at 400-600°C). In relation to this, the first well of the Icelandic Deep Drilling Project (IDDP) was drilled in Krafla in 2009. Drilling stopped at a depth of 2.1 km, when the drill string penetrated a rhyolitic magma body, which could not be bypassed despite attempts to side-track the well. This pioneering effort demonstrated that the area close to magma had great energy potential. Here we seek a constraint on the mechanical properties of reservoir rocks overlying the magmatic systems to gain knowledge on these systems to improve energy extraction. During two field surveys in 2015 and 2016, and through information gathered from drilling of geothermal wells, five main rock types were identified and sampled [and their porosities (i.e., storage capacities) where determined with a helium-pycnometer]: basalts (5-60% porosity), hyaloclastites (geothermal reservoir. Uniaxial and triaxial compressive strength tests have been carried out, as well as indirect tensile strength tests using the Brazilian disc method, to measure the rock strengths. The results show that the rock strength is inversely proportional to the porosity and strongly affected by the abundance of microcracks; some of the rocks are unusually weak considering their porosities, especially at low effective pressure as constrained at Krafla. The results also show that the porous lithologies may undergo significant compaction at relatively low loads (i.e., depth). Integration of the observed mechanical behaviour and

  19. Thermo-hydro-mechanical behaviour of Boom clay; Comportement thermo-hydro-mecanique de l'argile de Boom

    Energy Technology Data Exchange (ETDEWEB)

    Le, T.T

    2008-01-15

    This thesis studied the thermo-hydro-mechanical properties of Boom clay, which was chosen to be the host material for the radioactive waste disposal in Mol, Belgium. Firstly, the research was concentrated on the soil water retention properties and the hydro-mechanical coupling by carrying out axial compression tests with suction monitoring. The results obtained permitted elaborating a rational experimental procedure for triaxial tests. Secondly, the systems for high pressure triaxial test at controlled temperature were developed to carry out compression, heating, and shearing tests at different temperatures. The obtained results showed clear visco-elasto-plastic behaviour of the soil. This behaviour was modelled by extending the thermo-elasto-plastic model of Cui et al. (2000) to creep effect. (author)

  20. Effect of Heat Assisted Bath Sonication on the Mechanical and Thermal Deformation Behaviours of Graphene Nanoplatelets Filled Epoxy Polymer Composites

    Directory of Open Access Journals (Sweden)

    Jin-Luen Phua

    2016-01-01

    Full Text Available Graphene nanoplatelets (GNP filled epoxy composites ranged from 0.2 to 5 vol.% were prepared in this study using simple heat assisted bath sonication for better GNP dispersion and exfoliation. The effects of GNP filler loading via heat assisted bath sonication on the mechanical properties and thermal deformation behaviour were investigated. Improvements on flexural strength and fracture toughness up to 0.4 vol.% filler loading were recorded. Further addition of GNP filler loading shows a deteriorating behaviour on the mechanical properties on the composites. The bulk electrical conductivity of the epoxy composites is greatly improved with the addition of GNP filler loading up to 1 vol.%. The thermal expansion of epoxy composites is reduced with the addition of GNP; however poor thermal stability of the composites is observed.

  1. Post-operative duodenal fistula: percutaneous treatment and review

    Directory of Open Access Journals (Sweden)

    D.Huerta

    2015-04-01

    Full Text Available Duodenal fistula is a complex condition, relatively frequent presentation, being in most cases of postoperative origin. Among the latter, 6% to 11% are secondary to surgical treatment of perforated duodenal ulcer, and more unusual, as a complication of cholecystectomy. Two cases treated percutaneous at the Polyclinic Bank city of Buenos Aires are presented. The first, a female patient with a duodenal fistula as a postoperative complication of a perforated duodenal ulcer and the second one patient male with the same pathology but as a complication of cholecystectomy. Percutaneous treatment of this disease has been reported sporadically without having proven its usefulness. Once diagnosed the same Fistulography and obliteration were performed percutaneously achieving complete remission of the disease.

  2. Duodenal injuries due to trauma: Review of the literature.

    Science.gov (United States)

    García Santos, Esther; Soto Sánchez, Ana; Verde, Juan M; Marini, Corrado P; Asensio, Juan A; Petrone, Patrizio

    2015-02-01

    Duodenal injuries constitute a challenge to the Trauma Surgeon, mainly due to their retroperitoneal location. When identified, they present associated with other abdominal injuries. Consequently, they have an increased morbidity and mortality. At best estimates, duodenal lesions occur in 4.3% of all patients with abdominal injuries, ranging from 3.7% to 5%, and because of their anatomical proximity to other organs, they are rarely an isolated injury. The aim of this paper is to present a concise description of the anatomy, diagnosis, surgical management and treatment of complications of duodenal trauma, and an analysis of complications and mortality rates of duodenal injuries based on a 46-year review of the literature. Copyright © 2014 AEC. Publicado por Elsevier España, S.L.U. All rights reserved.

  3. Duodenal metastases of renal cell carcinoma: a case report

    Institute of Scientific and Technical Information of China (English)

    HE Xiang-hui; LU Ning; ZHANG Rui; ZHU Li-wei

    2010-01-01

    @@ Malignancy accounts for about 5% of upper gastrointestinal hemorrhage and needs to be treated by surgical intervention. Duodenal metastases are a rare and peculiar cause of upper gastrointestinal bleeding.

  4. Duodenal gangliocytic paraganglioma: A case report and literature review

    Directory of Open Access Journals (Sweden)

    Tyler J. Loftus

    2015-01-01

    Conclusion: Localized duodenal gangliocytic paragangliomas are best managed by resection with negative margins. In cases in which the tumor is resected with negative margins, it appears to be safe to embark on a course of surveillance and forego adjuvant therapy.

  5. Helicobacter pylori in duodenal ulcer disease and its eradication

    Directory of Open Access Journals (Sweden)

    Sengupta S

    2002-01-01

    Full Text Available Antral biopsy specimens were processed for Helicobacter pylori by Gram staining, rapid urease test (RUT and culture from 25 patients with symptoms of duodenal ulcer, amongst whom the positivity rate was 84%. Follow up of 16 patients after appropriate therapy showed complete regression of the disease in 87.5% of cases whereas in 12.5% of cases a decrease in the extent of duodenal ulceration was noted.

  6. Isolated duodenal rupture due to blunt abdominal trauma

    Directory of Open Access Journals (Sweden)

    Celik Atilla

    2006-01-01

    Full Text Available Duodenal rupture following blunt abdominal trauma is rare and it usually seen with other abdominal organ injuries. It represents approximately 2% to 20% of patients with blunt abdominal injury and often occurs after blows to the upper abdomen, or abdominal compression from high-riding seat belts. Two cases of blunt duodenal rupture successfully treated surgically, are presented with their preoperative diagnosis and final out comes.

  7. Therapeutic angiography for giant bleeding gastro-duodenal artery pseudoaneurysm

    Institute of Scientific and Technical Information of China (English)

    Ram; Elazary; Mahmoud; Abu-Gazala; Avraham; Schlager; Noam; Shussman; Avraham; I; Rivkind; Allan; I; Bloom

    2010-01-01

    We present the case of an 18-year-old female transferred to our center from an outside hospital due to persistent gastrointestinal bleeding. Two weeks prior to her transfer she underwent duodenal omentopexy for a perforated duodenal peptic ulcer. The patient underwent a computed tomography angiogram which identified the source of bleeding as a giant gastroduodenal artery (GDA) pseudoaneurysm. The patient was taken to interventional radiology where successful microcoil embolization was performed. We present ...

  8. Malignant transformation of ectopic pancreatic cells in the duodenal wall

    Institute of Scientific and Technical Information of China (English)

    Roberto; Bini; Paolo; Voghera; Alberto; Tapparo; Raffaele; Nunziata; Andrea; Demarchi; Matteo; Capocefalo; Renzo; Leli

    2010-01-01

    Ectopic pancreas (EP) is the relatively uncommon presence of pancreatic tissue outside the normal location of the pancreas. This condition is usually asymptomatic and rarely complicated by pancreatitis and malignant transformation. A few cases of neoplastic phenomena that developed from EP into the duodenal wall are described in the literature. Herein we report a case of gastric outlet obstruction due to adenocarcinoma arising from EP of the duodenal wall. The patient underwent a Whipple's procedure and had...

  9. Omeprazole promotes proximal duodenal mucosal bicarbonate secretion in humans.

    OpenAIRE

    Mertz-Nielsen, A; Hillingsø, J; Bukhave, K; Rask-Madsen, J

    1996-01-01

    The proton pump inhibitor, omeprazole, surprisingly resulted in higher rates of proximal duodenal mucosal bicarbonate secretion than previously reported using an H2 receptor antagonist for gastric acid inhibition. Gastroduodenal perfusions were performed in healthy volunteers to evaluate whether this incidental finding is explained by more potent gastric acid inhibition by omeprazole or might be caused by the different mode of drug action. Basal and stimulated gastric and duodenal bicarbonate...

  10. Clarification of the mechanical behaviour of spinal motion segments through a three-dimensional poroelastic mixed finite element model.

    Science.gov (United States)

    Wu, J S; Chen, J H

    1996-04-01

    The purpose of this study is to clarify the mechanical behaviour of spinal motion segments through a proper numerical model. The model constructed can give correct information and provide medical fields with valuable guidance in solving clinical problems occurring in the spine. A three-dimensional poroelastic finite element model of spinal motion segments is constructed and a mixed formulation is introduced. The geometry of the model is automatically formed from a series of CT-scanning images. Vertebral column, intervertebral joint, facet joints and ligaments are all included in the model. The contact surface of facet joints is considered as the inclined boundary. Such inclination is imposed when the contact surface is under compression. Ligaments surrounding the vertebral body and the intervertebral disc are put into the model when they are under tension. Iteration is implemented in the computing process to meet such boundary characteristics of facet joints and ligaments. Prediction of the mechanical behaviour in the segment under long term creep loading, is demonstrated using the current algorithm. Results show that the model and corresponding numerical procedures developed here can simulate the mechanical behaviour of the spinal motion segments properly.

  11. Simultaneous use of different communication mechanisms leads to spatial sorting and unexpected collective behaviours in animal groups.

    Science.gov (United States)

    Eftimie, Raluca

    2013-11-21

    Communication among individuals forms the basis of social interactions in every animal population. In general, communication is influenced by the physiological and psychological constraints of each individual, and in large aggregations this means differences in the reception and emission of communication signals. However, studies on the formation and movement of animal aggregations usually assume that all individuals communicate with neighbours in the same manner. Here, we take a new approach on animal aggregations and use a nonlocal mathematical model to investigate theoretically the simultaneous use of two communication mechanisms by different members of a population. We show that the use of multiple communication mechanisms can lead to behaviours that are not necessarily predicted by the behaviour of subpopulations that use only one communication mechanism. In particular, we show that while the use of one communication mechanism by the entire population leads to deterministic movement, the use of multiple communication mechanisms can lead in some cases to chaotic movement. Finally, we show that the use of multiple communication mechanisms leads to the sorting of individuals inside aggregations: individuals that are aware of the location and the movement direction of all their neighbours usually position themselves at the centre of the groups, while individuals that are aware of the location and the movement direction of only some neighbours position themselves at the edges of the groups. © 2013 Elsevier Ltd. All rights reserved.

  12. Oleoylethanolamide dose-dependently attenuates cocaine-induced behaviours through a PPARα receptor-independent mechanism.

    Science.gov (United States)

    Bilbao, Ainhoa; Blanco, Eduardo; Luque-Rojas, María Jesús; Suárez, Juan; Palomino, Ana; Vida, Margarita; Araos, Pedro; Bermúdez-Silva, Francisco J; Fernández-Espejo, Emilio; Spanagel, Rainer; Rodríguez de Fonseca, Fernando

    2013-01-01

    Oleoylethanolamide (OEA) is an acylethanolamide that acts as an agonist of nuclear peroxisome proliferator-activated receptor alpha (PPARα) to exert their biological functions, which include the regulation of appetite and metabolism. Increasing evidence also suggests that OEA may participate in the control of reward-related behaviours. However, direct experimental evidence for the role of the OEA-PPARα receptor interaction in drug-mediated behaviours, such as cocaine-induced behavioural phenotypes, is lacking. The present study explored the role of OEA and its receptor PPARα on the psychomotor and rewarding responsiveness to cocaine using behavioural tests indicative of core components of addiction. We found that acute administration of OEA (1, 5 or 20 mg/kg, i.p.) reduced spontaneous locomotor activity and attenuated psychomotor activation induced by cocaine (20 mg/kg) in C57Bl/6 mice. However, PPARα receptor knockout mice showed normal sensitization, although OEA was capable of reducing behavioural sensitization with fewer efficacies. Furthermore, conditioned place preference and reinstatement to cocaine were intact in these mice. Our results indicate that PPARα receptor does not play a critical, if any, role in mediating short- and long-term psychomotor and rewarding responsiveness to cocaine. However, further research is needed for the identification of the targets of OEA for its inhibitory action on cocaine-mediated responses.

  13. [Perforated duodenal diverticula. Case report and treatment options].

    Science.gov (United States)

    Guardado-Bermúdez, Fernando; Ardisson-Zamora, Fernando Josafat; Rojas-González, Juan Daniel; Medina-Benítez, Alberto; Corona-Suárez, Fernando

    2013-01-01

    the presence of duodenal diverticula was first described in 1710 by Chromel. Duodenal diverticulum is the second most common site of diverticula in the digestive tract. Anatomically duodenal diverticula are located in 10 to 67% in the second portion of duodenum, and its finding in most cases incidental. About 90% of patients appear asymptomatic, manifesting symptoms mostly once established complications such as: gastrointestinal bleeding and perforation. 78-years-old woman who attended our Emergency department with dyspnea, moderate epigastralgia, abdominal bloating, constipation and difficulty to pass gas; Laparotomy was performed to identify duodenal diverticulum in the third portion of the duodenum with a perforation of 5 mm in its cupula. It proceeds with diverticulectomy. The diagnosis of duodenal diverticulum as a cause of acute abdomen must be considered in our differential diagnosis in acute abdomen supported by imaging and endoscopy. The surgical management of duodenal diverticulum, in particular the resection of the diverticulum, remains as the recommendation for treatment with less morbidity and a good recovery.

  14. Duodenal White Spots Mimicking Intestinal Candidiasis: Report of Case

    Directory of Open Access Journals (Sweden)

    Ozgur Turk

    2015-12-01

    Full Text Available Duodenal white spots are mentioned in these nonspecific lesions until recently. Although there is not enough studies about duedonal white spots yet; these lesions described in a separate syndrome. Here now we reported a case that we diagnosed multiple Duodenal white spots mimicking intestinal candidiasis. Clinical manifestation and endoscopic appearance of lesions gave rise to thought intestinal candidiasis histopathological examination revealed us several duodenitis. There was no evidence of fungal infection in PAS staining. Early after endoscopy patient took treatment of Lansoprozole at the 30 mg dose and bismuth salicylate. Patients compliant declined and control endoscopy exposed white duodenal spots cleared away three months later. Duodenal white spots are becoming to be designated as a separate disease even a syndrome. Etiology of duodenal white spots must be determined carefully during endoscopy. Sometimes it is difficult to make the correct diagnosis by appearance of lesion; in such cases histopathological examination can be useful both differential diagnosis of disease and determination of etiological factor. [J Contemp Med 2015; 5(4.000: 249-252

  15. Functional dyspepsia is associated with duodenal eosinophilia in an Australian paediatric cohort.

    Science.gov (United States)

    Wauters, L; Nightingale, S; Talley, N J; Sulaiman, B; Walker, M M

    2017-05-01

    The pathophysiology of functional dyspepsia (FD) remains unknown. Duodenal eosinophil infiltration has been reported. To assess the association between dyspeptic symptoms and duodenal eosinophilia in children undergoing upper gastrointestinal endoscopy. In this retrospective cohort study, children with normal upper endoscopy and routine histology at a single tertiary paediatric centre between 2010 and 2014 were included. FD was defined as epigastric pain or discomfort >2 months without response to acid suppression. Controls presented with nonerosive reflux disease, dysphagia or rumination syndrome. Intramucosal eosinophil counts were compared between the groups using uni- and multivariate regression analyses. Thirty-six cases and 36 nonmatched controls were identified. Atopic history (39% vs. 25%) and psychological comorbidity (53% vs. 39%; both P = 0.2) were frequent in cases and controls. Self-reported nausea (64% vs. 17%; P 112 eosinophils per mm(2) predictive for FD (OR: 33.6, 95% CI: 7.1-159.0; P eosinophilia was associated with weight loss (OR: 7.1, 95% CI: 1.1-45.5; P = 0.04). Functional dyspepsia in children is strongly associated with duodenal eosinophilia, in the absence of endoscopic or routine histological findings. Frequent atopic and psychological comorbidity illustrate likely multifactorial mechanisms. © 2017 John Wiley & Sons Ltd.

  16. Helicobacter pylori and gastric or duodenal ulcer.

    Science.gov (United States)

    2016-01-01

    In patients with gastric or duodenal ulcer associated with Helicobacter pylori, treatment of the infection improves healing and prevents complications and recurrences. The drug regimen generally consists of a high-dose proton-pump inhibitor (PPI) such as omeprazole plus antibiotics. Using the standard Prescrire methodology, we conducted a review of the literature in order to determine the standard empirical antibiotic regimen for H. pylori infection in adults with gastric or duodenal ulcer in France. In 2015, due to an increase in H. pylori resistance to clarithromycin, a 7-day course of the PPI + clarithromycin + amoxicillin combination is effective in only about 70% of cases. A Cochrane systematic review and meta-analysis of trials involving thousands of patients suggests that prolonging treatment with a PPI + amoxicillin + clarithromycin or a PPI + amoxicillin + metronidazole to 10 or 14 days improves the rate of H. pylori eradication by 5% to 10%. A metanalysis of seven trials including a total of about 1000 patients showed that combination therapy with a PPI + amoxicillin + clarithromycin + metronidazole for 5 days eradicates H. pylori in about 90% of cases, compared to about 80% of cases with a PPI + amoxicillin + clarithromycin given for 7 days. Sequential treatment with amoxicillin for 5 days, followed by clarithromycin + metronidazole for 5 days, has also been tested in thousands of patients. Efficacy and adverse effects were similar to those observed when the same antibiotics were taken simultaneously for 5 days. In randomised trials, replacing clarithromycin or amoxicillin with a fluoroquinolone yielded conflicting results. In 2009, nearly 20% of H. pylori isolates were resistant to levofloxacin in France. Tetracycline has only been evaluated in combination with bismuth. The few available data on doxycycline suggest that its efficacy is similar to that of tetracycline. A fixed-dose combination of bismuth subcitrate potassium + metronidazole

  17. Impact of Offshore Wind Energy Plants on the Soil Mechanical Behaviour of Sandy Seafloors

    Science.gov (United States)

    Stark, Nina; Lambers-Huesmann, Maria; Zeiler, Manfred; Zoellner, Christian; Kopf, Achim

    2010-05-01

    Over the last decade, wind energy has become an important renewable energy source. Especially, the installation of offshore windfarms offers additional space and higher average wind speeds than the well-established windfarms onshore. Certainly, the construction of offshore wind turbines has an impact on the environment. In the framework of the Research at Alpha VEntus (RAVE) project in the German offshore wind energy farm Alpha Ventus (north of the island Borkum in water depths of about 30 m) a research plan to investigate the environmental impact had been put into place. An ongoing study focuses on the changes in soil mechanics of the seafloor close to the foundations and the development of scour. Here, we present results of the first geotechnical investigations after construction of the plants (ca. 1 - 6 months) compared to geotechnical measurements prior to construction. To study the soil mechanical behaviour of the sand, sediment samples from about thirty different positions were measured in the laboratory to deliver, e.g., grain size (0.063 - 0.3 mm), friction angles (~ 32°), unit weight (~ 19.9 kN/m³) and void ratios (~ 0.81). For acoustic visualisation, side-scan-sonar (towed and stationary) and multibeam-echosounders (hull mounted) were used. Data show a flat, homogenous seafloor prior to windmill erection, and scouring effects at and in the vicinity of the foundations afterwards. Geotechnical in-situ measurements were carried out using a standard dynamic Cone Penetration Testing lance covering the whole windfarm area excluding areas in a radius 50 %) occur above all close to the foundations. Furthermore, patterns of relatively soft zones (qsbc.: 50 - 80 kPa) and hard zones (qsbc. > 100 kPa) were mapped during the high-resolution surveys close to the foundation. Beside that, a very soft sediment layer (0.03 - 0.05 m) drapes most of the soft zones. This may be recently eroded and re-deposited sediment, whereas the hard zones may indicate areas of sediment

  18. Experimental characterization and mechanical behaviour modelling of molybdenum-titanium carbide composite for high temperature applications

    Energy Technology Data Exchange (ETDEWEB)

    Cedat, D.; Libert, M.; Rey, C.; Clavel, M.; Schmitt, J.H. [Ecole Cent Paris, MSSMAT, F-92295 Chatenay Malabry (France); Le Flem, M. [CEA Saclay, DEN, DANS, DMN, SRMA, 91 - Gif-sur-Yvette (France); Fandeur, O. [CEA Saclay, DEN, DANS, DM2S, SEMT, LM2S, 91 - Gif-sur-Yvette (France)

    2009-03-15

    Simulations of the elastic-viscoplastic behaviour of ceramic-metal composite, over the temperature range 298-993 K, are performed on realistic aggregates built up from electron back scatter diffraction methods. Physical based constitutive models are developed in order to characterize the deformation behaviour of body centered cubic (bcc) metal and face centered cubic (fcc) ceramic under various temperatures. While the ceramic keeps elastic, the viscoplastic behaviour of the metal part is described with a dislocation - based model, implemented in the finite element code ABAQUS, in order to compute local strain and stress fields during compressive tests. It is shown that the adopted constitutive laws are able to give back local complex experimental evidence on weak points of the microstructure. (authors)

  19. Experimental characterization and mechanical behaviour modelling of MoTiC composite for high temperature applications

    Energy Technology Data Exchange (ETDEWEB)

    Cedat, D.; Rey, C.; Clavel, M.; Schmitt, J.H. (MSSMAT, CNRS, Chatenay-Malabry (France)); Fandeur, O. (CEA DEN/DANS/DM2S/SEMT/LM2S, Gif-sur-Yvette (France)); Le Flem, M. (CEA DEN/DANS/DMN/SRMA, Gif-sur-Yvette (France))

    2008-10-15

    Simulations of the elastic-viscoplastic behaviour of ceramic-metal composite, over the temperature range 298-993K, are performed on realistic aggregates built up from Electron Back Scatter Diffraction methods. While the ceramic keeps elastic, the viscoplastic behaviour of the metal part is described with a dislocation-based model, implemented in the finite element code ABAQUS, in order to compute local strain and stress fields during compressive tests. It is shown that the adopted constitutive laws are able to give back local complex experimental evidence on weak points of the microstructure. (au)

  20. Numerical modelling of suffusion by discrete element method: a new internal stability criterion based on mechanical behaviour of eroded soil

    Science.gov (United States)

    Abdoulaye Hama, Nadjibou; Ouahbi, Tariq; Taibi, Said; Souli, Hanène; Fleureau, Jean-Marie; Pantet, Anne

    2017-06-01

    Non-cohesive soils subjected to a flow may have a behavior in which fine particles migrate through the interstices of the solid skeleton formed by the large particles. This phenomenon is termed internal instability, internal erosion or suffusion, and can occur both in natural soil deposits and also in geotechnical structures such as dams, dikes or barrages. Internal instability of a granular material is its inability to prevent the loss of its fine particles under flow effect. It is geometrically possible if the fine particles can migrate through the pores of the coarse soil matrix and results in a change in its mechanical properties. In this work, we uses the three-dimensional Particle Flow Code (PFC3D/DEM) to study the stability/instability of granular materials and their mechanical behavior. Kenney and Lau criterion sets a safe boundary for engineering design. However, it tends to identify stable soils as unstable ones. The effects of instability and erosion, simulated by clipping fine particles from the grading distribution, on the mechanical behaviour of glass ball samples were analysed. The mechanical properties of eroded samples, in which erosion is simulated and gives a new approach for internal stability. A proposal for a new internal stability criterion is established, it is deduced from the analysis of relations between the mechanical behaviour and internal stability, including material contractance.

  1. Microstructure, mechanical behaviour and fracture of pure tungsten wire after different heat treatments

    DEFF Research Database (Denmark)

    Zhao, P.; Riesch, J.; Höschen, T.

    2017-01-01

    and that embrittlement is caused by the loss of the preferable elongated grain structure rather than by recrystallization. In addition, a detailed evaluation of the plastic deformation behaviour during tensile test gives guidance to the design and optimization of tungsten fibre-reinforced composites....

  2. Cognitive Mechanisms and Behaviours Involved in Other than Institutional Learning and Using Principles of Decision

    Science.gov (United States)

    1980-02-01

    Task Oriented Group" pp 291-321 in The Simulation of flumai Behaviour, NATO Conierence of 1967 in Paris published (Ed De Bresson , F and Montmollin, Hi...K.Kianear, G E R (1976) C3 at Sea. In Procs. Workshop on Decision Information for Tactical Commanders, Spublished by Robert h Thrall and Assocs

  3. The Dynamics of Chinese Face Mechanisms and Classroom Behaviour: A Case Study

    Science.gov (United States)

    Wu, Xiaoxin

    2009-01-01

    Research on cross-cultural psychology, anthropology and sociology reveals that the impact of face on social interactions is both pervasive and powerful in Asia. Face, however, has not gained general acceptance as an important theoretical concept in the literature on Asian (Chinese in particular) classroom behaviour and management. This article…

  4. The Formation of Conservation-Based Behaviour of Mechanical Engineering Students through Contextual Learning Approach

    Science.gov (United States)

    Sudarman; Djuniadi; Sutopo, Yeri

    2017-01-01

    This study was aimed to figure out: (1) the implementation of contextual learning approaches; (2) the learning outcome of conservation education using contextual approach on the internship program preparation class; (3) the conservation-based behaviour of the internship program participants; (4) the contribution of conservation education results…

  5. Mechanical behaviour of a fibrous scaffold for ligament tissue engineering: finite elements analysis vs. X-ray tomography imaging.

    Science.gov (United States)

    Laurent, Cédric P; Latil, Pierre; Durville, Damien; Rahouadj, Rachid; Geindreau, Christian; Orgéas, Laurent; Ganghoffer, Jean-François

    2014-12-01

    The use of biodegradable scaffolds seeded with cells in order to regenerate functional tissue-engineered substitutes offers interesting alternative to common medical approaches for ligament repair. Particularly, finite element (FE) method enables the ability to predict and optimise both the macroscopic behaviour of these scaffolds and the local mechanic signals that control the cell activity. In this study, we investigate the ability of a dedicated FE code to predict the geometrical evolution of a new braided and biodegradable polymer scaffold for ligament tissue engineering by comparing scaffold geometries issued from FE simulations and from X-ray tomographic imaging during a tensile test. Moreover, we compare two types of FE simulations the initial geometries of which are issued either from X-ray imaging or from a computed idealised configuration. We report that the dedicated FE simulations from an idealised reference configuration can be reasonably used in the future to predict the global and local mechanical behaviour of the braided scaffold. A valuable and original dialog between the fields of experimental and numerical characterisation of such fibrous media is thus achieved. In the future, this approach should enable to improve accurate characterisation of local and global behaviour of tissue-engineering scaffolds.

  6. Mechanical behaviour of granular materials used in analogue modelling: insights from grain characterisation, ring-shear tests and analogue experiments

    Science.gov (United States)

    Panien, Marion; Schreurs, Guido; Pfiffner, Adrian

    2006-09-01

    The mechanical behaviour of several dry granular materials is investigated through ring-shear tests, grain characterisation, and simple analogue experiments analysed by X-ray computed tomography. An improved knowledge of granular materials is essential to determine their suitability as analogues for upper crustal rocks in experimental models and to compare analogue and numerical experiments. The ring-shear tests show that the granular materials have an elastic/frictional plastic behaviour with strain-hardening preceding failure at peak strength, followed by strain softening until a dynamic-stable value is reached. This is similar to the behaviour exhibited by experimentally deformed rocks. The physical characteristics of the grains determine the amount of diffuse deformation before failure, the percentage of strain softening and act on the thickness of the shear zones before broadening. Initial shear zone width in extensional and contractional experiments is between 11 and 16 times the mean grain size. The angle of internal friction defining one of the mechanical properties of granular materials and thus fault dip is not only related to physical characteristics of the grains and to the handling technique used (e.g. sieving or pouring), but also to the overburden and to the experimental setup used.

  7. Amylase: creatinine clearance ratio and urinary excretion of lysozyme in acute pancreatitis and acute duodenal perforation.

    Science.gov (United States)

    Berger, G M; Cowlin, J; Turner, T J

    1976-09-18

    The amylase:creatinine clearance ratio in patients suffering from acute pancreatitis or acute duodenal perforation was higher than normal in both groups of patients. These findings cast doubt on the value of this parameter as a specific index of acute pancreatitis. The mechanism or mechanisms underlying the increased amylase excretion have not been determined. However, the markedly elevated urinary excretion of lysozyme observed in some patients suggests, by analogy, that diminished tubular reabsorption of amylase may contribute towards the elevated amylase:creatinine ratio.

  8. The terminal web of the duodenal enterocyte.

    Science.gov (United States)

    Leeson, T S

    1982-06-01

    The terminal web-brush border complex of rodent duodenal enterocytes has been studied by electron microscopy to investigate its structure in relation to currently accepted models of motility in this region. The main adherens zone is composed chiefly of a fine feltwork of 5 to 7 nm filaments, some of which originate in zonulae adherentes. In some cells, this is not a complete layer or sheet. Passing into it from its deep aspect are 10 nm tonofilaments, which also form the basal zone. The filament density in the basal zone is less than that of the adherens zone, and many of the tonofilaments are associated with spot desmosomes. The apical zone contains a loose meshwork of 5 to 7 nm filaments with more filaments lying adjacent to plasmalemmae of the zonula occludens. The core of each microvillus contains a bundle of 17 to 48 microfilaments, 5-7 nm in diameter, apparently attached to the apical plasmalemma and with some slender cross filaments between core filaments and the plasmalemma. In the main, these core bundles of microfilaments pass deeply into and often through the adherens zone of the terminal web where they terminate abruptly. Filaments of the terminal web appear to interconnect microfilaments of adjacent core bundles but without positive evidence of 'splaying' of microfilaments of a core bundle within the adherens zone. These findings are discussed in relation to movement of microvilli.

  9. Perforated duodenal ulcer in Asir central hospital

    Directory of Open Access Journals (Sweden)

    Jastaniah Suleiman

    1997-01-01

    Full Text Available In a study of 27 cases of perforated duodenal ulcer seen at Asir Central Hospital over a period of seven years, two patients were females and 25 males. The highest incidence was in the fourth decade and the average age was 36.3 years. The Saudi-foreigner ratio was 1:2.9 in an area where the Saudi-foreigner population ratio was 1:3. Nine patients (33.3% were previously diagnosed as having peptic ulcer and had received treatment at one time or the other before perforation. Eighteen patients (66.7% were first diagnosed to peptic ulcer after the perforation. All the identified perforations were located anteriorly and anterosuperiorly. Only one case occurred in the second part of duodenum. The rest occurred in the first part. Two patients were treated successfully conservatively. The month perforations occurred most was the month of Shaaban. The fasting period during the month of Ramadhan did not show any increase in the prevalence of perforation in this hospital.

  10. Vitamin D-enhanced duodenal calcium transport.

    Science.gov (United States)

    Wongdee, Kannikar; Charoenphandhu, Narattaphol

    2015-01-01

    For humans and rodents, duodenum is a very important site of calcium absorption since it is exposed to ionized calcium released from dietary complexes by gastric acid. Calcium traverses the duodenal epithelium via both transcellular and paracellular pathways in a vitamin D-dependent manner. After binding to the nuclear vitamin D receptor, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] upregulates the expression of several calcium transporter genes, e.g., TRPV5/6, calbindin-D9k, plasma membrane Ca(2+)-ATPase1b, and NCX1, thereby enhancing the transcellular calcium transport. This action has been reported to be under the regulation of parathyroid-kidney-intestinal and bone-kidney-intestinal axes, in which the plasma calcium and fibroblast growth factor-23 act as negative feedback regulators, respectively. 1,25(OH)2D3 also modulates the expression of tight junction-related genes and convective water flow, presumably to increase the paracellular calcium permeability and solvent drag-induced calcium transport. However, vitamin D-independent calcium absorption does exist and plays an important role in calcium homeostasis under certain conditions, particularly in neonatal period, pregnancy, and lactation as well as in naturally vitamin D-impoverished subterranean mammals.

  11. Models of the behaviour of (thermally stressed) microbial spores in foods: tools to study mechanisms of damage and repair.

    Science.gov (United States)

    Ter Beek, Alex; Hornstra, Luc M; Pandey, Rachna; Kallemeijn, Wouter W; Smelt, Jan P P M; Manders, Erik M M; Brul, Stanley

    2011-06-01

    The 'Omics' revolution has brought a wealth of new mechanistic insights in many fields of biology. It offers options to base predictions of microbial behaviour on mechanistic insight. As the cellular mechanisms involved often turn out to be highly intertwined it is crucial that model development aims at identifying the level of complexity that is relevant to work at. For the prediction of microbiologically stable foods insight in the behaviour of bacterial spore formers is crucial. Their chances of germination and likelihood of outgrowth are major food stability indicators, as well as the transition from outgrowth to first cell division and vegetative growth. Current available technology to assess these parameters in a time-resolved manner at the single spore level will be discussed. Tools to study molecular processes operative in heat induced damage will be highlighted.

  12. Non-linear viscoelastic method to study the mechanical behaviour of case-bonded composite modified double base propellant charges

    Energy Technology Data Exchange (ETDEWEB)

    Meili, G.; Dubroca, G.; Pasquier, M.; Thepenier, J.

    1982-06-01

    The paper discusses a method for the mechanical testing of casebonded composite modified double base charges (CMDB) subjected to thermal cycling. The method proposed to determine stresses and safety margins takes into account the non-linear viscoelastic behaviour and the compressibility of the propellant. The non-linear behaviour is derived from tensile testing. The equations of equilibrium are solved numerically by deviding the grain web into many layers. The nonlinearities mainly concern the modulus; a multiaxial criterion and the time-temperature shift factors are used. At each time-step and for each layer the temperature, the reduced time, the non-linear factor, the Poisson's ratio and the damage according to the concept of Farris are calculated. Different charges (star, wagon wheel, finocyl) were subjected to various types of thermal cycles. The comparison between prediction and experimentation is acceptable even for complex histories in strain and temperature.

  13. Effect of sucralfate on gastric emptying in duodenal ulcer patients

    Energy Technology Data Exchange (ETDEWEB)

    Petersen, J.M.; Caride, V.J.; Prokop, E.K.; Troncale, F.; McCallum, R.W.

    1985-05-01

    Duodenal ulcer (DU) patients may have accelerated gastric emptying (GE) suggesting that there is an increase in unbuffered gastric acid reaching the duodenum contributing to DU disease. Aluminum-containing antacids were shown to delay GE. The authors' aim was to investigate whether another aluminum-containing compound, Sucralfate, affects GE in normal and DU patients. Nine normal volunteers and 10 patients with documented DU disease were studied. For each test the subject ingested a meal composed of chicken liver Tc-99m-S-C mixed with beef stew and eaten with 4 oz. of water labelled with 100..mu..Ci of III-in-DTPA. On two separate days, subjects received 1 gram of Sucralfate (190 mg of aluminum per gram) or placebo in a randomized double-blind fashion one hour prior to the test meal. GE of liquids and solids in normal subjects was not significantly changed by Sucralfate. Sucralfate in the DU patients significantly slowed liquid emptying in the initial 40 min and solid food throughout the study compared to placebo (p<0.05). This paper summarizes that; GE of solids but not liquids is accelerated in DU patients compared to normal subjects; and sucralfate delays GE of both liquid and solid components of a meal in DU patients but has no effect on GE in normals. The authors conclude that a slowing of gastric emptying possibly mediated by aluminum ions, may be one mechanism by which Sucralfate enhances healing and decreases recurrence of DU.

  14. Formulation and evaluation of omeprazole tablets for duodenal ulcer

    Directory of Open Access Journals (Sweden)

    Choudhury A

    2010-01-01

    Full Text Available Omeprazole pellets containing mucoadhesive tablets were developed by direct punch method. Three mucoadhesive polymers namely hydroxypropylemethylcellulose K4M, sodium carboxy methylcellulose, carbopol-934P and ethyl cellulose were used for preparation of tablets which intended for prolong action may be due to the attachment with intestinal mucosa for relief from active duodenal ulcer. Mucoadhesive tablets were coated with respective polymer and coated with Eudragit L100 to fabricate enteric coated tablets. The prepared tablets were evaluated for different physical parameters and dissolution study were performed in three dissolution mediums like 0.1N hydrochloric acid for 2h, pH 6.5 and pH 7.8 phosphate buffer solution for 12hr. Sodium carboxymethylcellulose showed above 95% release within 10 h where as carbopol-934P showed slow release about 88% to 92% over a period of 12 h. having excellent mucoadhesive strength but ethyl cellulose containing tablets showed less than 65% release. The release mechanism of all formulation was diffusion controlled confirmed from Higuchi′s plot. Thus, the present study concluded that, carbopol-934P containing mucoadhesive tablets of omeprazole pellets can be used for local action in the ulcer disease as well as for oral controlled release drug delivery.

  15. [Frequency, diagnosis and dependance of duodenitis upon the morphological status of the gastric mucosa (author's transl)].

    Science.gov (United States)

    Konstantinidis, T; Wagner, P K

    1978-08-01

    In a attempt to prove the dependence of duodenitis upon the morphological status of the gastric mucosa, a biopsy of the corpus, antrum, and duodenal canal had been made of 354 patients. In 56 cases, a superficial duodenitis was histologically verified; however, this infection had not contaminated the Brunner' glands. A duodenitis was found to be more often associated with surface gastritis of the corpus and antrum than it was with atropic gastritis. A duodenitis was discovered by a biopsy in 16 patients possessing a normal antrum mucosa and in 25 patients having a normal corpus mucosa, thus proving the possibility of isolated duodenitis.

  16. Assay of gastrin and somatostatin in gastric antrum tissues of children with chronic gastritis and duodenal ulcer

    Institute of Scientific and Technical Information of China (English)

    Xiao-Zhi Xie; Zhi-Guang Zhao; Dan-Si Qi; Zong-Min Wang

    2006-01-01

    AIM: To study the expressions of gastrin (GAS) and somatostatin (SS) in gastric antrum tissues of children with chronic gastritis and duodenal ulcer and their role in pathogenic mechanism.METHODS: Specimens of gastric antrum mucosa from 83 children were retrospectively analyzed. Expressions of GAS and SS in gastric antrum tissues were assayed by the immunohistochemical En Vision method.RESULTS: The expressions of GAS in chronic gastritis Hp+ group (group A), chronic gastritis Hp- group (group B), the duodenal ulcer Hp+group (group C), duodenal ulcer Hp- group (group D), and normal control group (group E) were 28.50+4.55, 19.60+2.49, 22.69+2.71,25.33 + 4.76, and 18.80 + 2.36, respectively. The value in groups A-D was higher than that in group E. The difference was not statistically significant. The expressions of SS in groups A-E were 15.47 + 1.44, 17.29 + 2.04,15.30 + 1.38, 13.11 + 0.93 and 12.14 + 1.68, respectively.The value in groups A-D was higher than that in group E.The difference was also not statistically significant.CONCLUSION: The expressions of GAS and SS are increased in children with chronic gastritis and duodenal ulcer.

  17. A pure bending machine to identify the mechanical behaviour of thin sheets

    OpenAIRE

    Arnold, Gilles; Calloch, Sylvain; Dureisseix, David; Billardon, René

    2003-01-01

    International audience; It is now commonly accepted that the so-called Baushinger effect has to be taken into account for accurate springback predictions during sheet metal forming simulations. Baushinger effect can be modelled through the introduction of a kinematic hardening law in the material model. The identification of such a behaviour requires to perform tests such that the material is subjected to reversal loadings. In the case of thin sheets, tension-compression tests are impossible ...

  18. Prevalence and Clinical, Endoscopic, and Pathological Features of Duodenitis in Children.

    Science.gov (United States)

    Alper, Arik; Hardee, Steven; Rojas-Velasquez, Danilo; Escalera, Sandra; Morotti, Raffaella A; Pashankar, Dinesh S

    2016-02-01

    Although gastritis and esophagitis are well studied in children, there is very limited literature on duodenitis in children. We aimed to assess the prevalence, etiology, clinical, endoscopic, and pathological features in a large cohort of unselected children with duodenitis. We reviewed the pathology reports of all the upper endoscopies performed at our institution during 5 years to identify children with duodenitis. Biopsy sections were reviewed to confirm the diagnosis of duodenitis. Demographic, clinical, endoscopic data, and the presence of associated gastritis and esophagitis were noted in all of the children with duodenitis. The etiology of duodenitis was correlated with the patients' clinical diagnosis. Out of 2772 children who had endoscopy, 352 had duodenitis with the prevalence rate of 12.7%. Gastritis was seen in 64% of children with duodenitis compared with 46% of children without duodenitis (P < 0.001). Common indications for endoscopy in children with duodenitis were abdominal pain, positive celiac serology, and diarrhea. The most common etiology was celiac disease (32%), followed by Crohn disease (13%), ulcerative colitis (3%), and Helicobacter pylori infection (6%). In 63% of cases, the endoscopic appearance of duodenum was normal. Cryptitis, villous changes, and cellular infiltration were noted on histology. Prevalence of duodenitis is 12.7% in children undergoing endoscopy. Celiac disease and inflammatory bowel disease are common causes of duodenitis. Associated gastritis is common in children with duodenitis, and the correlation of endoscopic appearance with histology is poor.

  19. Mechanical behaviour of wood T-joints. Experimental and numerical investigation

    Directory of Open Access Journals (Sweden)

    C.L. dos Santos

    2015-01-01

    Full Text Available Results of a double-shear single-dowel wood connection tested under monotonic quasi-static compression loading are presented and discussed in this paper. The wood used in this study was a pine wood, namely the Pinus pinaster species, which is one of the most important Portuguese species. Each connection (specimen consists of three wood members: a centre member, loaded in compression along the parallel-tograin direction and two simply supported side members, loaded along the perpendicular-to-grain direction (Tconnection. The load transfer between wood members was assured by means of a steel dowel, which is representative of the most common joining technique applied for structural details in wooden structures. The complete load-slip behaviour of the joint is obtained until failure. In particular, the values of the stiffness, the ultimate loads and the ductility were evaluated. Additionally, this investigation proposed non-linear 3D finite element models to simulate the T-joint behaviour. The interaction between the dowel and the wood members was simulated using contact finite elements. A plasticity model, based on Hill’s criterion, was used to simulate the joint ductility and cohesive damage modelling was applied to simulate the brittle failure modes (splitting observed in the side members of the joint. The simulation procedure allowed a satisfactory description of the non-linear behaviour of the T-joint including the collapse prediction.

  20. Primary duodenal neoplasms: A retrospective clinico-pathological analysis

    Science.gov (United States)

    Bal, Amanjit; Joshi, Kusum; Vaiphei, Kim; Wig, JD

    2007-01-01

    AIM: To analyze the clinico-pathological spectrum of primary duodenal neoplasms. METHODS: A total of 55 primary duodenal neoplasms reported in the last 10 years after excluding ampullary and periampullary tumors were included in the study. Clinical details were noted and routine hematoxylin and eosin stained paraffin sections were studied for histological subtyping of the tumors. RESULTS: On histopathological examination primary duodenal neoplasms were categorized as: epithelial tumor in 27 cases (49.0%) including 10 cases of adenoma, 15 cases of adenocarcinoma, and 2 cases of Brunner gland adenoma; mesenchymal tumor in 9 cases (16.3%) consisting of 4 cases of gastrointestinal stromal tumor, 4 cases of smooth muscle tumor and I case of neurofibroma; lymphoproliferative tumor in 12 cases (21.8%), and neuroendocrine tumor in 7 cases (12.7%). CONCLUSION: Although non-ampullary/periampullary duodenal adenocarcinomas are rare, they constitute the largest group. Histopathological examination of primary duodenal tumors is important for correct histological subtyping. PMID:17373748

  1. Primary duodenal neoplasms:A retrospective clinico-pathological analysis

    Institute of Scientific and Technical Information of China (English)

    Amanjit Bal; Kusum Joshi; Kim Vaiphei; JD Wig

    2007-01-01

    AIM:To analyze the clinico-pathological spectrum of primary duodenal neoplasms.METHODS:A total of 55 primary duodenal neoplasms reported in the last 10 years after excluding ampullary and periampullary tumors were included in the study.Clinical details were noted and routine hematoxylin and eosin stained paraffin sections were studied for histological subtyping of the tumors.RESULTS:On histopathological examination primary duodenal neoplasms were categorized as:epithelial tumor in 27 cases(49.0%)including 10 cases of adenoma,15 cases of adenocarcinoma,and 2 cases of Brunner gland adenoma;mesenchymal tumor in 9 cases (16.3%)consisting of 4 cases of gastrointestinal stromal tumor,4 cases of smooth muscle tumor and I case of neurofibroma;lymphoproliferative tumor in 12 cases (21.8%),and neuroendocrine tumor in 7 cases(12.7%).CONCLUSION:Although non-ampullary/periampullary duodenal adenocarcinomas are rare,they constitute the largest group.Histopathological examination of primary duodenal tumors is important for correct histological subtyping.

  2. Lifing the thermo-mechanical fatigue (TMF behaviour of the polycrystalline nickel-based superalloy RR1000

    Directory of Open Access Journals (Sweden)

    Jones Jonathan

    2014-01-01

    Full Text Available Microstructural damage and subsequent failures resulting from thermo-mechanical fatigue (TMF loading within the temperature range 300–700 ∘C are investigated for the polycrystalline nickel superalloy, RR1000. Strain controlled TMF experiments were conducted over various mechanical strain ranges, encompassing assorted phase angles, using hollow cylindrical test pieces. The paper explores two scenarios; the first where the mechanical strain range is held constant and comparisons of the fatigue life are made for different phase angle tests, and secondly, the difference between the behaviour of In-phase (IP and − 180 ∘ Out-Of-Phase (OOP tests over a variety of applied strain ranges. It is shown that different lifing approaches are currently required for the two scenarios, with a mean stress based approach being more applicable in the first case, whereas a Basquin-type model proves more appropriate in the second.

  3. Does Ramadan Fasting Increase duodenal ulcer perforation?

    Directory of Open Access Journals (Sweden)

    Abdoulhossein Davoodabadi

    2016-03-01

    Full Text Available Introduction: In Ramadan, healthy adult Muslims are obliged to fast. Prolonged fasting increase gastric acid and pepsin levels, which promote the risk of duodenal ulcer perforation (DUP. Effects of Ramadan fasting on DUP have not been thoroughly studied yet, and the limited number of studies investigating the impact of Ramadan fasting on DUP yielded discrepant results. This study aimed to evaluate DUP frequency during Ramadan 2011-2015 and compare it with other months. Methods: This cross-sectional study was performed in 82 patients undergoing surgery due to DUP during July 2011-September 2015. The demographics, history of addiction, use of nonsteroidal and antiinflammatory drugs, previous history of acid peptic disease, as well as complications and outcomes of treatment were recorded and analyzed, and the obtained results were compared between Ramadan and other lunar months. Results: The majority of patients were male (86.6%, 71 patients, with a mean age of 43.9±16.5 years (age range: 20-75 years. Male to female ratio was 6:1. Cases with less than 30 years of age were less frequent (22%, 18 patients. DUP was more frequent during Rajab with nine cases (11%, while during Ramadan, six cases were reported, the difference between Ramadan and other months regarding the incidence of DUP was not significant (P=0.7. Risk factors such as smoking (60% and addiction (44%; especially to crystal and crack were noted. Consumption of nonsteroidal antiinflammatory drugs in 20 (24% patients, and use of antacids in 17 (25% patients. Distribution of DUP in different blood types was as follows: O+=41%, A+=28%, B+=23%, AB=5%, and O-=3%; moreover, post-operative Helicobacter pylori antibody was present in 67% of the patients. Conclusion: Ramadan fasting did not escalate DUP incidence, and those with DUP risk factors can fast with the use of antacids.

  4. An unusual case of duodenal perforation caused by a blister pack: A case report and literature review

    Directory of Open Access Journals (Sweden)

    Si-Yuan Yao

    2015-01-01

    Conclusion: Unnoticed ingestion of blister packs can cause duodenal perforation. Although prompt management is necessary, duodenal perforation, especially in the third portion, may be potentially fatal.

  5. Duodenal adenocarcinoma: Advances in diagnosis and surgical management

    Institute of Scientific and Technical Information of China (English)

    Jordan M Cloyd; Elizabeth George; Brendan C Visser

    2016-01-01

    Duodenal adenocarcinoma is a rare but aggressive malignancy. Given its rarity, previous studies have traditionally combined duodenal adenocarcinoma(DA) with either other periampullary cancers or small bowel adenocarcinomas, limiting the available data to guide treatment decisions. Nevertheless, management primarily involves complete surgical resection when technically feasible. Surgery may require pancreaticoduodenectomy or segmental duodenal resection; either are acceptable options as long as negative margins are achievable and an adequate lymphadenectomy can be performed. Adjuvant chemotherapy and radiation are important components of multi-modality treatment for patients at high risk of recurrence. Further research would benefit from multiinstitutional trials that do not combine DA with other periampullary or small bowel malignancies. The purpose of this article is to perform a comprehensive review of DA with special focus on the surgical management and principles.

  6. Acyclovir in the prevention of duodenal ulcer recurrence

    DEFF Research Database (Denmark)

    Rune, S J; Linde, J; Bonnevie, O;

    1990-01-01

    This study tests the hypothesis that reactivation of a latent herpes simplex virus infection may be a cause of recurrent duodenal ulceration. Patients with recently healed duodenal ulcer were entered into a double blind, randomised study of maintenance treatment with the antiviral drug acyclovir...... (400 mg bid) versus placebo, to determine if suppression of herpes virus infection would influence the natural history of the ulcer disease. One hundred and fifteen patients entered the trial and 76 patients completed it according to the protocol. Endoscopy was performed when ulcer symptoms recurred...... and at the end of the 25 week trial period. In the acyclovir group the cumulated relapse rate was 63% compared with 56% in the placebo group (NS). This result suggests that reactivation of herpes simplex virus is not a cause of recurrent duodenal ulcer....

  7. Tratamiento laparoscópico de la membrana duodenal

    Directory of Open Access Journals (Sweden)

    Luis Ricardo García-Vázquez

    Full Text Available La membrana duodenal congénita se presenta con mayor frecuencia en la región ampular, y se expresa clínicamente como obstrucción intestinal durante el periodo neonatal. En algunos escenarios el diagnóstico de esta condición clínica pasa inadvertida cuando dicha membrana es incompleta, como en los casos de membrana duodenal fenestrada. En consecuencia, se modifica la forma de presentación y se dificulta su diagnóstico temprano. Se cuenta con distintos accesos terapéuticos para esta enfermedad, desde los abiertos, hasta los endoscópicos y laparoscópicos. Se presenta el caso de una lactante con diagnóstico tardío de membrana duodenal fenestrada, que se trató quirúrgicamente mediante acceso laparoscópico.

  8. A newborn with duodenal atresia and a gastric perforation

    Directory of Open Access Journals (Sweden)

    Akcora Bulent

    2010-01-01

    Full Text Available Congenital duodenal atresia complicated by gastric perforation (GP is a very rare and a very mortal condition. Only three newborns could be cured in the reported 13 cases. We report a successfully treated newborn with this complicated disease. A 2-day-old male was hospitalized with prediagnosis of duodenal obstruction. Twelve hours later, significant abdominal distention occurred promptly. At laparotomy, GP and preampullary duodenal atresia were detected. Gastrorrhaphy and duodenoduodenostomy were performed in the same operation. The patient was discharged on the 15th postoperative day. This complicated disease can be treated by early diagnosis and surgical intervention. We choose one-stage operation because of the clean peritoneal cavity. However, generalized peritonitis may require two-stage operation in delayed cases.

  9. Laparoscopic gastric partitioning gastrojejunostomy for an unresectable duodenal malignant tumor

    Directory of Open Access Journals (Sweden)

    Matsumoto Toshifumi

    2005-01-01

    Full Text Available As a palliative bypass for unresectable gastric or periampullary cancer, gastrojejunostomy (GJ is sometimes associated with postoperative delayed gastric emptying. We report the successful laparoscopic application of this procedure in a 78-year-old man with duodenal obstruction. Computed tomography revealed a mass in the duodenum along with multiple masses in the liver. A radiological image showed an ulcerative tumour in the third portion of the duodenum occluding the lumen. He was diagnosed as having an unresectable duodenal cancer with multiple liver metastases. He needed palliative bypass surgery. Laparoscopically, the stomach was partially divided using an endoscopic autosuture device, and end-to-side GJ was performed successfully. He was given a normal diet on the fourth postoperative day, and there was no delayed gastric emptying. Laparoscopic gastric partitioning GJ is a feasible and safe procedure to prevent postoperative delayed gastric emptying in case of malignant duodenal obstruction.

  10. A Rare Cause of Acute Pancreatitis: Intramural Duodenal Hematoma

    Directory of Open Access Journals (Sweden)

    Hemant Goyal

    2012-01-01

    Full Text Available We describe an interesting case of intramural duodenal hematoma in an otherwise healthy male who presented to emergency room with gradually progressive abdominal pain, nausea, and vomiting. This condition was missed on initial evaluation and patient was discharged from emergency room with diagnosis of acute gastritis. After 3 days, patient came back to emergency room and abdominal imaging studies were conducted which showed that patient had intramural duodenal hematoma associated with gastric outlet obstruction and pancreatitis. Hematoma was the cause of acute pancreatitis as pancreatic enzymes levels were normal at the time of first presentation, but later as the hematoma grew in size, it caused compression of pancreas and subsequent elevation of pancreatic enzymes. We experienced a case of pancreatitis which was caused by intramural duodenal hematoma. This case was missed on initial evaluation. We suggest that physicians should be more vigilant about this condition.

  11. Upper gastrointestinal barium evaluation of duodenal pathology: A pictorial review

    Institute of Scientific and Technical Information of China (English)

    Pankaj; Gupta; Uma; Debi; Saroj; Kant; Sinha; Kaushal; Kishor

    2014-01-01

    Like other parts of the gastrointestinal tract(GIT), duodenum is subject to a variety of lesions both congenital and acquired. However, unlike other parts of the GIT viz. esophagus, rest of the small intestine and large intestine, barium evaluation of duodenal lesions is technically more challenging and hence not frequently reported. With significant advances in computed tomography technology, a thorough evaluation including intraluminal, mural and extramural is feasible in a single non-invasive examination. Notwithstanding, barium evaluation still remains the initial and sometimes the only imaging study in several parts of the world. Hence,a thorough acquaintance with the morphology of various duodenal lesions on upper gastrointestinal barium examination is essential in guiding further evaluation. We reviewed our experience with various common and uncommon barium findings in duodenal abnormalities.

  12. Study of nerve fibers nature reinforcing duodenal contractions by electrical stimulation of sympathetic nerve

    Directory of Open Access Journals (Sweden)

    Sveshnikov D.S.

    2011-09-01

    Full Text Available The subject of the article is to investigate the mechanism of increased reactions by electrical stimulation of the sympathetic nerve. Materials and methods: Experiments on dogs have shown that stimulant reactions during blockade of a-adrenergic by phentolamine and (3-adrenergic receptors with propranolol were completely eliminated by lizer-gol —the blocker of 5-HT12-receptors. Results: Infusion of lizergol did not influence on duodenal motor activity and the function of the vagus nerve. Conclusion: Effector neuron is found out to be serotonergic and its action is provided by 5-HT1 2 receptors

  13. A RETROSPECTIVE STUDY ON DUODENAL ULCER PERFORATION AND OUTCOME

    Directory of Open Access Journals (Sweden)

    Parameshwara Chaldiganahalli

    2016-02-01

    Full Text Available INTRODUCTION Duodenal ulcer disease which was once so common 3-4 decades ago has drastically decreased in its incidence due to invent of PPIs and anti H. Pylori therapy. But percentage of patients with complications of duodenal ulcer has not shown a similar decline. In spite of understanding the disease effective resuscitation and prompt surgery there is still High incidence of morbidity and mortality. Hence in this study an attempt is made to analyse the various factors which effect the morbidity, mortality of patients with duodenal ulcer perforation and management of the same. AIMS The objective is to study, 1. The factors responsible for duodenal ulcer perforation. 2. The factors that affect the post-operative outcome. 3. Morbidity, mortality after surgery. MATERIALS AND METHODS Fifty patient’s case sheets were selected retrospectively who were diagnosed as duodenal ulcer perforation, admitted in MIMS Hospital, Mandya. Between 2012 to 2014 patients underwent Graham's omentoplasty. All the data related to the objectives of the study were collected. RESULTS Majority of patients belong to the. Age group of 30-50 years and commonly males Most of the perforations occur in first part of duodenum low socio-economic group, O+ve blood group with maximum seasonal incidence in October-January All cases were managed by Graham's omentoplasty. Four per cent of mortality noted. CONCLUSION Duodenal ulcer perforation is one of the common acute abdominal emergencies. The peak incidence between 30 and 50 years, majority cases males, common in lower socio–economic group, unskilled workers, maximum incidence period October-January, increased morbidity and mortality when perforation time period >24 hours, maximum in patient with blood group o+, early diagnosis and septicaemia management necessary for patients better prognosis, emergency procedure is Graham’s omentoplasty (perforations<2cm with H. pylori eradication treatment. Mortality noticed in longer

  14. A Statistical Approach To Prediction Of The CMM Drift Behaviour Using A Calibrated Mechanical Artefact

    Directory of Open Access Journals (Sweden)

    Cuesta Eduardo

    2015-09-01

    Full Text Available This paper presents a multivariate regression predictive model of drift on the Coordinate Measuring Machine (CMM behaviour. Evaluation tests on a CMM with a multi-step gauge were carried out following an extended version of an ISO evaluation procedure with a periodicity of at least once a week and during more than five months. This test procedure consists in measuring the gauge for several range volumes, spatial locations, distances and repetitions. The procedure, environment conditions and even the gauge have been kept invariables, so a massive measurement dataset was collected over time under high repeatability conditions. A multivariate regression analysis has revealed the main parameters that could affect the CMM behaviour, and then detected a trend on the CMM performance drift. A performance model that considers both the size of the measured dimension and the elapsed time since the last CMM calibration has been developed. This model can predict the CMM performance and measurement reliability over time and also can estimate an optimized period between calibrations for a specific measurement length or accuracy level.

  15. Experiments on thermo-hydro-mechanical behaviour of Opalinus Clay at Mont Terri rock laboratory, Switzerland

    Directory of Open Access Journals (Sweden)

    Paul Bossart

    2017-06-01

    Full Text Available Repositories for deep geological disposal of radioactive waste rely on multi-barrier systems to isolate waste from the biosphere. A multi-barrier system typically comprises the natural geological barrier provided by the repository host rock – in our case the Opalinus Clay – and an engineered barrier system (EBS. The Swiss repository concept for spent fuel and vitrified high-level waste (HLW consists of waste canisters, which are emplaced horizontally in the middle of an emplacement gallery and are separated from the gallery wall by granular backfill material (GBM. We describe here a selection of five in-situ experiments where characteristic hydro-mechanical (HM and thermo-hydro-mechanical (THM processes have been observed. The first example is a coupled HM and mine-by test where the evolution of the excavation damaged zone (EDZ was monitored around a gallery in the Opalinus Clay (ED-B experiment. Measurements of pore-water pressures and convergences due to stress redistribution during excavation highlighted the HM behaviour. The same measurements were subsequently carried out in a heater test (HE-D where we were able to characterise the Opalinus Clay in terms of its THM behaviour. These yielded detailed data to better understand the THM behaviours of the granular backfill and the natural host rock. For a presentation of the Swiss concept for HLW storage, we designed three demonstration experiments that were subsequently implemented in the Mont Terri rock laboratory: (1 the engineered barrier (EB experiment, (2 the in-situ heater test on key-THM processes and parameters (HE-E experiment, and (3 the full-scale emplacement (FE experiment. The first demonstration experiment has been dismantled, but the last two ones are on-going.

  16. Delayed duodenal hematoma and pancreatitis from a seatbelt injury.

    Science.gov (United States)

    Deambrosis, Katherine; Subramanya, Manjunath S; Memon, Breda; Memon, Muhammed A

    2011-02-01

    Traumatic duodenal hematoma is a rare condition that is encountered in the paediatric age group following blunt abdominal trauma. It poses both a diagnostic and therapeutic challenge. The main concern is increased morbidity secondary to delayed diagnosis and associated occult injuries to the adjacent structures. Most of these hematomas resolve spontaneously with conservative management, and the prognosis is good. We present a case of a 15-year-old boy who had a delayed presentation of duodenal hematoma and acute pancreatitis, which was treated conservatively with complete resolution.

  17. Delayed Duodenal Hematoma and Pancreatitis from a Seatbelt Injury

    Directory of Open Access Journals (Sweden)

    DeAmbrosis, Katherine

    2011-02-01

    Full Text Available Traumatic duodenal hematoma is a rare condition that is encountered in the paediatric age group following blunt abdominal trauma. It poses both a diagnostic and therapeutic challenge. The main concern is increased morbidity secondary to delayed diagnosis and associated occult injuries to the adjacent structures. Most of these hematomas resolve spontaneously with conservative management, and the prognosis is good. We present a case of a 15-year-old boy who had a delayed presentation of duodenal hematoma and acute pancreatitis, which was treated conservatively with complete resolution. [West J Emerg Med. 2011;12(1:128-130.

  18. A Lethal Complication of Endoscopic Therapy: Duodenal Intramural Hematoma

    Directory of Open Access Journals (Sweden)

    Turan Calhan

    2015-01-01

    Full Text Available Duodenal intramural hematoma (DIH usually occurs in childhood and young adults following blunt abdominal trauma. It may also develop in the presence of coagulation disorders and may rarely be an iatrogenic outcome of endoscopic procedures. Management of DIH is usually a conservative approach. A case of intramural duodenal hematoma that developed following endoscopic epinephrine sclerotherapy and/or argon plasma coagulation and that was nonresponsive to conservative therapy in a patient with chronic renal failure who died from sepsis is being discussed in this report. Clinicians should be aware of such possible complications after endoscopic hemostasis in patients with coagulation disorders.

  19. Gastric outlet obstruction from duodenal lipoma in an adult

    Directory of Open Access Journals (Sweden)

    Promise N Wichendu

    2013-01-01

    Full Text Available The duodenum is a rare site for gastrointestinal lipoma with less than 230 cases reported in the literature. Although, peptic ulcer disease remains the most common benign cause of gastric outlet obstruction (GOO, duodenal lipomas remain a rare, but possible cause of GOO and could pose a diagnostic challenge, especially in countries where access to endoscopy and modern imaging techniques poses a challenge. The authors present a case of GOO in a 40-year-old male, secondary to a duodenal lipoma. It was successfully treated by a transduodenal resection through a midline laparotomy. The histology report confirmed it was a submucosal lipoma.

  20. Isolated perforation of a duodenal diverticulum following blunt abdominal trauma

    Directory of Open Access Journals (Sweden)

    Metcalfe Matthew

    2010-01-01

    Full Text Available Only 10% of duodenal diverticula are symptomatic. We present the case of a man who fell from a height of 6 ft, landing on his abdomen and presenting 4 h later with severe back pain and a rigid abdomen. At laparotomy, a perforated retroperitoneal duodenal diverticulum was found and repaired with an omental patch. No other injury was noted. Not only is this perforation unusual, but the absence of other injuries sustained during this minor blunt trauma makes this case unique. This case highlights the need for a high index of suspicion when managing patients with back or abdominal pain following minor trauma.

  1. MRI findings of intrinsic and extrinsic duodenal abnormalities and variations

    Energy Technology Data Exchange (ETDEWEB)

    Atman, Ebru Dusunceli; Erden, Ayse; Ustuner, Evren; Uzun, Caglar; Bektas, Mehmet [Ankara University School of Medicine, Ankara (Turkmenistan)

    2015-12-15

    This pictorial review aims to illustrate the magnetic resonance imaging (MRI) findings and presentation patterns of anatomical variations and various benign and malignant pathologies of the duodenum, including sphincter contraction, major papilla variation, prominent papilla, diverticulum, annular pancreas, duplication cysts, choledochocele, duodenal wall thickening secondary to acute pancreatitis, postbulbar stenosis, celiac disease, fistula, choledochoduodenostomy, external compression, polyps, Peutz-Jeghers syndrome, ampullary carcinoma and adenocarcinoma. MRI is a useful imaging tool for demonstrating duodenal pathology and its anatomic relationships with adjacent organs, which is critical for establishing correct diagnosis and planning appropriate treatment, especially for surgery.

  2. The incidence and prognosis of true duodenal carcinomas

    DEFF Research Database (Denmark)

    Buchbjerg, Thomas; Fristrup, C.; Mortensen, M. B.

    2015-01-01

    Introduction Primary duodenal carcinoma (PDC) is a rare gastrointestinal tumor. The difficult distinction between PDC and other types of carcinoma (e.g. within the periampullary region) is reflected in the scarce literature on true duodenal carcinomas. However, this distinction may be important...... the criteria for true PDC. The incidence was 5.4 per 1,000,000, and the pathological classification was: Adenocarcinoma 87%, mucinous adenocarcinoma 7%, carcinoma 4% and signet ring cell carcinoma 1%. Intended curative resection was performed in 28 patients (39%) (22 Whipple procedures and 6 local resections...

  3. Duodenal intussusception secondary to web presenting as recurrent pancreatitis in a 7-year-old girl

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Long H. [University of Connecticut School of Medicine, Farmington, CT (United States); Kaweah Delta Healthcare District, Graduate Medical Education, Visalia, CA (United States); Villalona, Gustavo A. [Yale School of Medicine, Department of Surgery, Section of Pediatric Surgery, New Haven, CT (United States); SSM Health Cardinal Glennon Children' s Hospital, Department of Pediatric Surgery, St. Louis, MO (United States); Cowles, Robert A. [Yale School of Medicine, Department of Surgery, Section of Pediatric Surgery, New Haven, CT (United States); Silva, Cicero T. [Yale School of Medicine, Department of Diagnostic Imaging, Section of Pediatric Radiology, 333 Cedar St., P.O. Box 208042, New Haven, CT (United States)

    2016-03-15

    Duodenal intussusception is a rare entity in children, with 32 cases reported in the English literature to our knowledge. Most reported cases are associated with endoluminal tubes or polyps, and the presenting symptoms are chronic and nonspecific. We report a case of duodenal intussusception in a 7-year-old girl secondary to a duodenal web and review the imaging findings. (orig.)

  4. Mechanical and Corrosion Behaviour of Zn-27Al Based Composites Reinforced with Groundnut Shell Ash and Silicon Carbide

    Directory of Open Access Journals (Sweden)

    K.K. Alaneme

    2014-06-01

    Full Text Available The mechanical and corrosion behaviour of Zn-27Al alloy based composites reinforced with groundnut shell ash and silicon carbide was investigated. Experimental test composite samples were prepared by melting Zn-27Al alloy with pre-determined proportions of groundnut ash and silicon carbide as reinforcements using double stir casting. Microstructural examination, mechanical properties and corrosion behaviour were used to characterize the composites produced. The results show that hardness and ultimate tensile strength of the hybrid composites decreased with increase in GSA content. Although the % Elongation somewhat decreased with increase the GSA content, the trend was not as consistent as that of hardness and tensile strength. The fracture toughness of the hybrid composites however, increased with increase in the GSA content of the composites. In 3.5 % NaCl solution, the composites were resistant to corrosion with some of the hybrid composite grades containing GSA exhibiting relatively superior corrosion resistance to the grades without GSA. In 0.3M H2SO4 solution, the composites were generally a bit more susceptible to corrosion (compared to 3.5 % NaCl solution, but the effect of GSA content on the corrosion resistance of the composites was not consistent for the Zn-27Al alloy based composites.

  5. Modelling the mechanical behaviour of pit membranes in bordered pits with respect to cavitation resistance in angiosperms.

    Science.gov (United States)

    Tixier, Aude; Herbette, Stephane; Jansen, Steven; Capron, Marie; Tordjeman, Philippe; Cochard, Hervé; Badel, Eric

    2014-08-01

    Various correlations have been identified between anatomical features of bordered pits in angiosperm xylem and vulnerability to cavitation, suggesting that the mechanical behaviour of the pits may play a role. Theoretical modelling of the membrane behaviour has been undertaken, but it requires input of parameters at the nanoscale level. However, to date, no experimental data have indicated clearly that pit membranes experience strain at high levels during cavitation events. Transmission electron microscopy (TEM) was used in order to quantify the pit micromorphology of four tree species that show contrasting differences in vulnerability to cavitation, namely Sorbus aria, Carpinus betulus, Fagus sylvatica and Populus tremula. This allowed anatomical characters to be included in a mechanical model that was based on the Kirchhoff-Love thin plate theory. A mechanistic model was developed that included the geometric features of the pits that could be measured, with the purpose of evaluating the pit membrane strain that results from a pressure difference being applied across the membrane. This approach allowed an assessment to be made of the impact of the geometry of a pit on its mechanical behaviour, and provided an estimate of the impact on air-seeding resistance. The TEM observations showed evidence of residual strains on the pit membranes, thus demonstrating that this membrane may experience a large degree of strain during cavitation. The mechanical modelling revealed the interspecific variability of the strains experienced by the pit membrane, which varied according to the pit geometry and the pressure experienced. The modelling output combined with the TEM observations suggests that cavitation occurs after the pit membrane has been deflected against the pit border. Interspecific variability of the strains experienced was correlated with vulnerability to cavitation. Assuming that air-seeding occurs at a given pit membrane strain, the pressure predicted by the model

  6. Effects of fibre content on mechanical properties and fracture behaviour of short carbon fibre reinforced geopolymer matrix composites

    Indian Academy of Sciences (India)

    Tiesong Lin; Dechang Jia; Meirong Wang; Peigang He; Defu Liang

    2009-02-01

    Geopolymer matrix composites reinforced with different volume fractions of short carbon fibres (Cf/geopolymer composites) were prepared and the mechanical properties, fracture behaviour and microstructure of as-prepared composites were studied and correlated with fibre content. The results show that short carbon fibres have a great strengthening and toughening effect at low volume percentages of fibres (3.5 and 4.5 vol.%). With the increase of fibre content, the strengthening and toughening effect of short carbon fibres reduce, possibly due to fibre damage, formation of high shear stresses at intersect between fibres and strong interface cohesion of fibre/matrix under higher forming pressure. The property improvements are primarily based on the network structure of short carbon fibre preform and the predominant strengthening and toughening mechanisms are attributed to the apparent fibre bridging and pulling-out effect.

  7. Attenuation of cysteamine-induced duodenal ulcer with Cochinchina momordica seed extract through inhibiting cytoplasmic phospholipase A2/5-lipoxygenase and activating γ-glutamylcysteine synthetase.

    Science.gov (United States)

    Choi, Ki-Seok; Kim, Eun-Hee; Hong, Hua; Ock, Chan Young; Lee, Jeong Sang; Kim, Joo-Hyun; Hahm, Ki-Baik

    2012-04-01

    Cysteamine is a reducing aminothiol used for inducing duodenal ulcer through mechanisms of oxidative stress related to thiol-derived H(2)O(2) reaction. Cochinchina momordica saponins have been suggested to be protective against various gastric diseases based on their cytoprotective and anti-inflammatory mechanisms. This study was aimed to document the preventive effects of Cochinchina momordica seed extract against cysteamine-induced duodenal ulcer as well as the elucidation of its pharmacological mechanisms. Cochinchina momordica seed extract (50, 100, 200 mg/kg) was administrated intragastrically before cysteamine administration, after which the incidence of the duodenal ulcer, ulcer size, serum gastrin level, and the ratio of reduced glutathione (GSH)/oxidized glutathione disulfide (GSSG) as well as biochemical and molecular measurements of cytoplasmic phospholipase A(2) (cPLA(2)), cyclooxygenase-2 (COX-2), 5-lipoxygenase and the expression of proinflammatory genes including IL-1β, IL-6, COX-2 were measured in rat model. Additional experiments of electron spin resonance measurement and the changes of glutathione were performed. Cochinchina momordica seed extract effectively prevented cysteamine-induced duodenal ulcer in a dose-dependent manner as reflected with significant decreases in either duodenal ulcerogenesis or perforation accompanied with significantly decreased in serum gastrin in addition to inflammatory mediators including cPLA(2), COX-2, and 5-lipoxygenase. Cochinchina momordica seed extract induced the expression of γ-glutamylcysteine synthetase (γ-GCS)-related glutathione synthesis as well as significantly reduced the expression of cPLA(2). Cochinchina momordica seed extract preserved reduced glutathione through increased expressions of γ-GCS. Cochinchina momordica seed extracts exerted significantly protective effect against cysteamine-induced duodenal ulcer by either cPLA2 inhibition or glutathione preservation. © 2012 Journal of

  8. Enhancement of the electrochemical behaviour and biological performance of Ti–25Ta–5Zr alloy by thermo-mechanical processing

    Energy Technology Data Exchange (ETDEWEB)

    Cimpean, Anisoara [Department of Biochemistry and Molecular Biology, University of Bucharest, Spl. Independentei, 91-95, 050095 Bucharest (Romania); Vasilescu, Ecaterina; Drob, Paula [Department of Electrochemistry and Corrosion, Institute of Physical Chemistry “Ilie Murgulescu” of Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Cinca, Ion, E-mail: ion_cinca@hotmail.com [Faculty of Material Science and Engineering, Politehnica University, Spl. Independentei 313, 060042 Bucharest (Romania); Vasilescu, Cora; Anastasescu, Mihai [Department of Electrochemistry and Corrosion, Institute of Physical Chemistry “Ilie Murgulescu” of Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Mitran, Valentina [Department of Biochemistry and Molecular Biology, University of Bucharest, Spl. Independentei, 91-95, 050095 Bucharest (Romania); Drob, Silviu Iulian [Department of Electrochemistry and Corrosion, Institute of Physical Chemistry “Ilie Murgulescu” of Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania)

    2014-05-01

    A new Ti–25Ta–5Zr alloy based only on non-toxic and non-allergic elements was elaborated in as-cast and thermo-mechanical processed, recrystallized states (XRD and SEM) in order to be used as candidate material for implant applications. Its long-term interactions with Ringer–Brown and Ringer solutions of different pH values and its cytocompatibility were determined. The thermo-mechanically processed alloy has nobler electrochemical behaviour than as-cast alloy due to finer microstructure obtained after the applied treatment. Corrosion and ion release rates presented the lowest values for the treated alloy. Nyquist and Bode plots displayed higher impedance values and phase angles for the processed alloy, denoting a more protective passive film. SEM micrographs revealed depositions from solutions that contain calcium, phosphorous and oxygen ions (EDX analysis), namely calcium phosphate. An electric equivalent circuit with two time constants was modelled. Cell culture experiments with MC3T3-E1 pre-osteoblasts demonstrated that thermo-mechanically processed Ti–25Ta–5Zr alloy supports a better cell adhesion and spreading, and enhanced cell proliferation. Altogether, these data indicate that thermo-mechanical treatment endows the alloy with improved anticorrosion and biological performances. - Highlights: • Ti–25Ta–5Zr alloy exhibited noble electrochemical, passive behaviour in simulated biofluids. • An electric equivalent circuit with two time constants was modelled. • Corrosion rates show the lowest values for the recrystallized Ti–25Ta–5Zr alloy. • In vitro tests revealed good cytocompatibility of as-cast and processed alloy. • Recrystallized treatment endows the alloy with superior biological performances.

  9. Job satisfaction as a unified mechanism for agent behaviour on a labour market with referral hiring

    OpenAIRE

    Tarvid, Alexander

    2014-01-01

    Existing agent-based labour-market models include a very simplistic mechanism of choosing vacancies. This paper proposes to use job satisfaction as a unified mechanism for deciding on both starting to work on a particular job and quitting the current job. An enhanced job satisfaction mechanism consisting of monetary, social, content, and career components is proposed. As an illustrative context, a labour-market model with referral hiring and informal job search through own social networks is ...

  10. Researches of mechanical behaviour of the bone micro volumes and porous ceramics under uniaxial compression

    Science.gov (United States)

    Kolmakova, T. V.; Buyakova, S. P.; Kulkov, S. N.

    2017-02-01

    The research results of the mechanics are presented and the effective mechanical characteristics under uniaxial compression of the simulative micro volume of the compact bone are defined subject to the direction of the collagen-mineral fibers, porosity and mineral content. The experimental and computer studies of the mechanics are performed and the effective mechanical characteristics of the porous zirconium oxide ceramics are defined. The recommendations are developed on the selection of the ceramic samples designed to replace the fragment of the compact bone of a definite structure and mineral content.

  11. Role of central histaminergic mechanism in behavioural depression (swimming despair) in mice.

    Science.gov (United States)

    Nath, C; Gulati, A; Dhawan, K N; Gupta, G P

    1988-01-01

    The role of the central histaminergic system in depression was studied by using swimming despair test in mice - a behavioural model of depression. In this test, immobility of mice reflects a state of depression. Intracerebral (ic) injection of histamine (50-200 micrograms) increased significantly the immobility. The H1-receptor blocker mepyramine (2.5-20 mg/kg ip) had no effect while H2-receptor blocker cimetidine (100-200 micrograms ic) caused a significant decrease in immobility. The histamine induced facilitation was blocked completely by cimetidine and antidepressant drugs-imipramine and desipramine, but remained unaffected in mice pretreated with mepyramine or atropine. The H2 agonist impromidine (20-40 micrograms ic) also enhanced significantly, the immobility which was blocked by cimetidine and antidepressant drugs. It has been concluded that central H2-receptors facilitate depression and antidepressant drugs block central H2-receptors.

  12. Shock machine for the mechanical behaviour of hip prostheses: a description of performance capabilities

    CERN Document Server

    Uribe, Juliana; Forest, Bernard; 10.1002/ls.167

    2012-01-01

    The aim of this study was to describe the behaviour of a shock machine designed for testing hip prostheses. A microseparation between head and cup occurs inducing a shock of several times the body weight, leading to fracture of ceramic femoral components. Femoral heads and cups of diameter 32 mm manufactured from alumina were tested in dry and wet conditions. Implants were subjected to shocks with a load profile of 9 kN load at 2 Hz and various microseparations. Position is monitored and force is measured with two acquisition systems. The working range and the device capabilities were investigated. Only cups tested in dry conditions failed. Observations by scanning electron microscopy revealed intergranular and transgranular fractures. Two wear stripes were observed on the heads. Three-dimensional roughness of wear stripes was measured. Since experimental results are in good agreement with retrieved femoral heads, the shocks machine reproduces the in vivo degradations.

  13. Novel deployment of a covered duodenal stent in open surgery to facilitate closure of a malignant duodenal perforation

    Directory of Open Access Journals (Sweden)

    Psaila Josephine

    2009-10-01

    Full Text Available Abstract Background Its a dilemma to attempt a palliative procedure to debulk the tumour and/or prevent future obstructive complications in a locally advanced intra abdominal malignancy. Case presentation A 38 year old Vietnamese man presented with a carcinoma of the colon which had invaded the gallbladder and duodenum with a sealed perforation of the second part of the duodenum. Following surgical exploration, it was evident that primary closure of the perforated duodenum was not possible due to the presence of unresectable residual tumour. Conclusion We describe a novel technique using a covered duodenal stent deployed at open surgery to aid closure of a malignant duodenal perforation.

  14. Optimising mechanical behaviour of new advanced steels based on fine non-equilibrium microstructures

    NARCIS (Netherlands)

    HajyAkbary, F.

    2015-01-01

    This Ph.D. thesis investigates the relation between microstructural and mechanical properties of Advanced High Strength Steels (AHSS), with the goal of developing a microstructure with optimised mechanical properties. Among different grades of AHSS, Quenching and Partitioning (Q&P) steel which is co

  15. Optimising mechanical behaviour of new advanced steels based on fine non-equilibrium microstructures

    NARCIS (Netherlands)

    HajyAkbary, F.

    2015-01-01

    This Ph.D. thesis investigates the relation between microstructural and mechanical properties of Advanced High Strength Steels (AHSS), with the goal of developing a microstructure with optimised mechanical properties. Among different grades of AHSS, Quenching and Partitioning (Q&P) steel which is

  16. Mechanical behaviour of dacite from Mount St. Helens (USA): A link between porosity and lava dome extrusion mechanism (dome or spine)?

    Science.gov (United States)

    Heap, M. J.; Russell, J. K.; Kennedy, L. A.

    2016-12-01

    There is a rich diversity in lava dome morphology, from blocky domes and lobes to imposing spine and whaleback structures. The latter extrude via seismically active, gouge-rich conduit-margin faults, a manifestation of a brittle failure mode. Brittle versus ductile behaviour in volcanic rocks is known to be porosity dependent, and therefore offers a tantalising link between the properties of the material near the conduit margin and the extrusion mechanism (dome or spine). We test this hypothesis by complementing published data on the mechanical behaviour of dacites from the 2004-2008 spine-forming eruption at Mount St. Helens (MSH) with new data on dacite lavas collected from the 1980 dome. The 1980 dacite samples were deformed at room temperature under a range of pressures (i.e., depths) to investigate their mechanical behaviour and failure mode (brittle or ductile). Low-porosity dacite (porosity 0.19) is brittle up to an effective pressure of 30 MPa (depth 1 km) and is ductile at 40 MPa (depth 1.5 km). High-porosity dacite (porosity 0.32) is ductile above an effective pressure of 5 MPa (depth 200 m). Samples deformed in the brittle regime show well-developed ( 1 mm) shear fracture zones comprising broken glass and crystal fragments. Samples deformed in the ductile regime feature anastomosing bands of collapsed pores. The combined dataset is used to explore the influence of strain rate, temperature, and porosity on the mechanical behaviour and failure mode of dacite. A decrease in strain rate does not influence the strength of dacite at low temperature, but reduces strength at high temperature (850 °C). Due to the extremely low glass content of these materials, such weakening is attributed to the increased efficiency of subcritical crack growth at high temperature. However, when strain rate is kept constant, temperature does not significant impact strength reflecting the highly crystallised nature of dacite from MSH. Dacite from the 2004-2008 eruption is stronger

  17. Effect of oral epidermal growth factor on mucosal healing in rats with duodenal ulcer

    Institute of Scientific and Technical Information of China (English)

    Jane CJ Chao; Kuo-Yu Liu; Sheng-Hsuan Chen; Chia-Lang Fang; Chih-Wei Tsao

    2003-01-01

    AIM: To investigate the effect of epidermal growth factor (EGF) on mucosal healing in rats with duodenal ulcer.METHODS: Male Sprague-Dawley rats were randomly divided into sham operation without EGF, sham operation with EGF, duodenal ulcer without EGF, or duodenal ulcer with EGF groups. Additionally, normal rats without operation served as the control group. Duodenal ulcer was induced in rats by 300 mL/L acetic acid. Rats with EGF were orally administered at a dose of 60 μg/kg/day in drinking water on the next day of operation (day 1). Healing of duodenal ulcer was detected by haematoxylin and eosin staining. Cell growth of damaged mucosa was determined by the contents of nucleic acids and proteins. The level of EGF in duodenal mucosa was measured by ELISA.RESULTS: The pathological results showed that duodenal ulcer rats with EGF improved mucosal healing compared with those without EGF after day 5. Duodenal ulcer rats with EGF significantly increased duodenal DNA content compared with those without EGF on day 15 (6.44±0.54mg/g VS 1.45±0.52 mg/g mucosa, P<0.05). Duodenal RNA and protein contents did not differ between duodenal ulcer rats with and without EGF during the experimental period.Sham operation and duodenal ulcer rats with EGF significantly increased duodenal mucosal EGF content compared with those without EGF on day 5 (76.0±13.7 ng/g VS 35.7±12.9ng/g mucosa in sham operation rats, and 68.3±10.9 ng/gVS 28.3±9.2 ng/g mucosa in duodenal ulcer rats, P<0.05).CONCLUSION: Oral EGF can promote mucosal healing of the rats with duodenal ulcer by stimulating mucosal proliferation accompanied by an increase in mucosal EGF content.

  18. Duodenal atresia in association with situs inversus abdominus

    Directory of Open Access Journals (Sweden)

    Raghu Shankar

    2012-01-01

    Full Text Available We report a rare association of duodenal atresia with situs inversus abdominus in a newborn. The infantogram revealed "reverse double-bubble sign" without dextrocardia. The sonography and echocardiography confirmed the diagnosis of situs inversus abdominus with multiple cardiac anomalies. Laparotomy and a duodenoduodenostomy were carried out.

  19. Gastric pneumatosis associated with duodenal stenosis and malrotation

    Energy Technology Data Exchange (ETDEWEB)

    Kawano, Shoji [Dept. of Paediatrics, Kawasaki Medical School, Okayama (Japan); Dept. of Paediatrics, Shimonoseki Municipal Hospital, Yamaguchi (Japan); Tanaka, Hiroyuki; Daimon, Yusuke; Niizuma, Takahiro; Terada, Kihei; Kataoka, Naoki [Dept. of Paediatrics, Kawasaki Medical School, Okayama (Japan); Iwamura, Yoshinobu; Aoyama, Kohji [Department of Paediatric Surgery, Kawasaki Medical School, Okayama (Japan)

    2001-09-01

    Pneumatosis intestinalis, which is linear or cystic gas within the bowel wall, is usually found in premature babies in association with necrotizing enterocolitis. Gastric pneumatosis defined as intramural gas of the stomach is a rare sign during infancy. We report an infant with Down's syndrome and a duodenal web with obvious gastric pneumatosis. (orig.)

  20. Spontaneous oesophageal rupture with duodenal atresia in a newborn infant.

    OpenAIRE

    1981-01-01

    A newborn infant with spontaneous oesophageal rupture associated with duodenal atresia is described. The diagnosis was established by the pattern of hydropneumothorax on the chest x-ray film and by the aspiration of gastric juice by thoracocentesis. Necropsy showed a tear, which extended from the oesophagogastric junction to the upper portion of the stomach.

  1. Orientation-dependent mechanical behaviour of electrodeposited copper with nanoscale twins.

    Science.gov (United States)

    Mieszala, Maxime; Guillonneau, Gaylord; Hasegawa, Madoka; Raghavan, Rejin; Wheeler, Jeffrey M; Mischler, Stefano; Michler, Johann; Philippe, Laetitia

    2016-09-21

    The mechanical properties of electrodeposited copper with highly-oriented nanoscale twins were investigated by micropillar compression. Uniform nanotwinned copper films with preferred twin orientations, either vertical or horizontal, were obtained by controlling the plating conditions. In addition, an ultrafine grained copper film was synthesized to be used as a reference sample. The mechanical properties were assessed by in situ SEM microcompression of micropillars fabricated with a focused ion beam. Results show that the mechanical properties are highly sensitive to the twin orientation. When compared to the ultrafine grained sample, an increase of 44% and 130% in stress at 5% offset strain was observed in quasi-static tests for vertically and horizontally aligned twins, respectively. Inversely strain rate jump microcompression testing reveals higher strain sensitivity for vertical twins. These observations are attributed to a change in deformation mechanism from dislocation pile-ups at the twin boundary for horizontal twins to dislocations threading inside the twin lamella for vertical twins.

  2. Mechanical and dynamic mechanical behaviour of novel glass–natural fibre intra-ply woven polyester composites

    Indian Academy of Sciences (India)

    M RAJESH; JEYARAJ PITCHAIMANI

    2017-07-01

    A novel intra-ply woven fabric polyester composite with glass fibre yarns in one direction and natural fibre yarns in another direction of basket-type woven fabric has been investigated for mechanical and dynamic mechanical characteristics. Individual glass fibre woven fabric, natural fibres woven fabric and intraplynatural fibres woven fabric composites are also investigated for the comparison purpose. Results reveal that the intra-ply woven fabric hybridization enhances impact and damping properties of the composite significantly than the tensile and flexural properties. Intra-ply woven fabrics with glass fibre yarns in warp direction and jute fibre yarns in weft direction (WGWJ) exhibit better impact properties compared with woven fabric with other combinations. Dynamic mechanical analysis results reveal that intra-ply woven fabric composite with glass fibreyarns in warp direction and jute and banana fibre yarns in weft direction (WGWJAB) gives higher damping characteristics due to the multi-level interaction between fibre–fibre and fibre–matrix interactions.

  3. Duodenal Toxicity After Fractionated Chemoradiation for Unresectable Pancreatic Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, Patrick; Das, Prajnan; Pinnix, Chelsea C.; Beddar, Sam; Briere, Tina; Pham, Mary; Krishnan, Sunil; Delclos, Marc E. [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Crane, Christopher H., E-mail: ccrane@mdanderson.org [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)

    2013-03-01

    Purpose: Improving local control is critical to improving survival and quality of life for patients with locally advanced unresectable pancreatic cancer (LAPC). However, previous attempts at radiation dose escalation have been limited by duodenal toxicity. In order to guide future studies, we analyzed the clinical and dosimetric factors associated with duodenal toxicity in patients undergoing fractionated chemoradiation for LAPC. Methods and Materials: Medical records and treatment plans of 106 patients with LAPC who were treated with chemoradiation between July 2005 and June 2010 at our institution were reviewed. All patients received neoadjuvant and concurrent chemotherapy. Seventy-eight patients were treated with conventional radiation to 50.4 Gy in 28 fractions; 28 patients received dose-escalated radiation therapy (range, 57.5-75.4 Gy in 28-39 fractions). Treatment-related toxicity was graded according to Common Terminology Criteria for Adverse Events, version 4.0. Univariate and multivariate analyses were performed to assess prognostic influence of clinical, pathologic, and treatment-related factors by using Kaplan-Meier and Cox regression methods. Results: Twenty patients had treatment-related duodenal toxicity events, such as duodenal inflammation, ulceration, and bleeding. Four patients had grade 1 events, 8 had grade 2, 6 had grade 3, 1 had grade 4, and 1 had grade 5. On univariate analysis, a toxicity grade ≥2 was associated with tumor location, low platelet count, an absolute volume (cm{sup 3}) receiving a dose of at least 55 Gy (V{sub 55} {sub Gy} > 1 cm{sup 3}), and a maximum point dose >60 Gy. Of these factors, only V{sub 55} {sub Gy} ≥1 cm{sup 3} was associated with duodenal toxicity on multivariate analysis (hazard ratio, 6.7; range, 2.0-18.8; P=.002). Conclusions: This study demonstrates that a duodenal V{sub 55} {sub Gy} >1 cm{sup 3} is an important dosimetric predictor of grade 2 or greater duodenal toxicity and establishes it as a

  4. Mechanical behaviour of membrane electrode assembly (MEA during cold start of PEM fuel cell from subzero environment temperature

    Directory of Open Access Journals (Sweden)

    Maher A.R. Sadiq Al-Baghdadi

    2015-01-01

    Full Text Available Durability is one of the most critical remaining issues impeding successful commercialization of broad PEM fuel cell transportation energy applications. Automotive fuel cells are likely to operate with neat hydrogen under load-following or load-levelled modes and be expected to withstand variations in environmental conditions, particularly in the context of temperature and atmospheric composition. In addition, they are also required to survive over the course of their expected operational lifetimes i.e., around 5,500 hrs, while undergoing as many as 30,000 startup/shutdown cycles. Cold start capability and survivability of proton exchange membrane fuel cells (PEM in a subzero environment temperature remain a challenge for automotive applications. A key component of increasing the durability of PEM fuel cells is studying the behaviour of the membrane electrode assembly (MEA at the heart of the fuel cell. The present work investigates how the mechanical behaviour of MEA are influenced during cold start of the PEM fuel cell from subzero environment temperatures. Full three-dimensional, non-isothermal computational fluid dynamics model of a PEM fuel cell has been developed to simulate the stresses inside the PEM fuel cell, which are occurring during fuel cell assembly (bolt assembling, and the stresses arise during fuel cell running due to the changes of temperature and relative humidity. The model is shown to be able to understand the many interacting, complex electrochemical, transport phenomena, and stresses distribution that have limited experimental data.

  5. Role of Silicon Dioxide Filler on Mechanical and Dry Sliding Wear Behaviour of Glass-Epoxy Composites

    Directory of Open Access Journals (Sweden)

    Naveed Anjum

    2013-01-01

    Full Text Available The mechanical properties and dry sliding wear behaviour of glass fabric reinforced epoxy (G-E composite with varying weight percentage of silicon dioxide (SiO2 filler have been studied in the present work. The influence of sliding distance, velocity, and applied normal load on dry sliding wear behaviour has been considered using Taguchi's L9 orthogonal array. Addition of SiO2 increased the density, hardness, flexural, and impact strengths of G-E composite. Results of dry sliding wear tests showed increasing wear volume with increase in sliding distance, load, and sliding velocity for G-E and SiO2 filled G-E composites. Taguchi's results indicate that the sliding distance played a significant role followed by applied load, sliding velocity, and SiO2 loading. Scanning electron micrographs of the worn surfaces of composite samples at different test parameters show smooth surface, microploughing, and fine grooves under low load and velocity. However, severe damage of matrix with debonding and fiber breakage was seen at high load and velocity especially in unfilled G-E composite.

  6. Studies on crystallization behaviour and mechanical properties of Al–Ni–La metallic glasses

    Indian Academy of Sciences (India)

    K L Sahoo; Rina Sahu; M Ghosh; S Chatterjee

    2008-06-01

    Alloy ingots with nominal composition, Al92–Ni8La ( = 4 to 6) and Al94–Ni6La ( = 6, 7), were prepared by induction melting in a purified Ar atmosphere. Each ingot was inductively re-melted and rapidly solidified ribbons were obtained by ejecting the melt onto a rotating copper wheel in an argon atmosphere. The crystallization behaviour of melt-spun amorphous ribbon was investigated by means of differential scanning calorimetry (DSC), X-ray diffractometry and transmission electron microscopy. DSC showed that Al86Ni8La6 alloy undergoes a three-stage and rest of the alloys undergo a two-stage crystallization process upon heating. The phases responsible for each stage of crystallization were identified. During the first crystallization stage fcc-Al precipitates for low La-containing alloys and for higher La-containing alloys a bcc metastable phase precipitates. The second crystallization stage is due to formation of intermetallic compounds along with fcc-Al. Microhardness of all the ribbons was examined at different temperatures and correlated with structural evolutions. Precipitation strengthening of nano-size fcc-Al is responsible for maximum hardness in these annealed alloys.

  7. Electrochemical behaviour of N-acetyl-L-cysteine on gold electrode - A tentative reaction mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Barus, C.; Gros, P.; Comtat, M. [Laboratoire de Genie Chimique, UMR 5503, Universite Paul Sabatier, Departement Procedes Electrochimiques, 31062 Toulouse Cedex 9 (France); Daunes-Marion, S.; Tarroux, R. [Societe Pierre Fabre Dermo-Cosmetique, Service Pharmocochimie, Allee Camille Soula, Vigoulet Auzil, BP 74, 31322 Castanet Tolosan (France)

    2007-11-01

    The electrochemical behaviour of N-acetyl-L-cysteine (NAC) has been investigated by linear and cyclic voltammetry on gold electrode at room temperature. The results showed two oxidation peaks under acid and neutral conditions and only one in basic medium. For each oxidation, as many electron was exchanged as proton. The influence of both the concentration and the potential scan rate on the peak currents highlighted a diffusion-controlled phenomenon for the first peak and an adsorption-limited reaction rate for the second one. The diffusion coefficient of NAC in solution and the surface concentration of the adsorbed species at pH 3 and 7 were close to 2 x 10{sup -4} to 2 x 10{sup -5} cm{sup 2} s{sup -1} and 6 x 10{sup -9} to 6 x 10{sup -10} mol cm{sup -2}, respectively. Film transfer experiments resulted in an irreversible adsorption of NAC on gold electrode, and the formation of a self-assembled monolayer (SAM). (author)

  8. Electrochemical behaviour of N-acetyl-L-cysteine on gold electrode-A tentative reaction mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Barus, C. [Laboratoire de Genie Chimique, UMR 5503, Universite Paul Sabatier, Departement Procedes Electrochimiques, 31062 Toulouse Cedex 9 (France)], E-mail: barus@chimie.ups-tlse.fr; Gros, P.; Comtat, M. [Laboratoire de Genie Chimique, UMR 5503, Universite Paul Sabatier, Departement Procedes Electrochimiques, 31062 Toulouse Cedex 9 (France); Daunes-Marion, S.; Tarroux, R. [Societe Pierre Fabre Dermo-Cosmetique, Service Pharmocochimie, Allee Camille Soula, Vigoulet Auzil, BP 74, 31322 Castanet Tolosan (France)

    2007-11-01

    The electrochemical behaviour of N-acetyl-L-cysteine (NAC) has been investigated by linear and cyclic voltammetry on gold electrode at room temperature. The results showed two oxidation peaks under acid and neutral conditions and only one in basic medium. For each oxidation, as many electron was exchanged as proton. The influence of both the concentration and the potential scan rate on the peak currents highlighted a diffusion-controlled phenomenon for the first peak and an adsorption-limited reaction rate for the second one. The diffusion coefficient of NAC in solution and the surface concentration of the adsorbed species at pH 3 and 7 were close to 2 x 10{sup -4} to 2 x 10{sup -5} cm{sup 2} s{sup -1} and 6 x 10{sup -9} to 6 x 10{sup -10} mol cm{sup -2}, respectively. Film transfer experiments resulted in an irreversible adsorption of NAC on gold electrode, and the formation of a self-assembled monolayer (SAM)

  9. Influence of the Geometric Parameters on the Mechanical Behaviour of Fabric Reinforced Composite Laminates

    Science.gov (United States)

    Axinte, Andrei; Taranu, Nicolae; Bejan, Liliana

    2016-10-01

    A polymer fabric reinforced composite is a high performance material, which combines strength of the fibres with the flexibility and ductility of the matrix. For a better drapeability, the tows of fibres are interleaved, resulting the woven fabric, used as reinforcement. The complex geometric shape of the fabric is of paramount importance in establishing the deformability of the textile reinforced composite laminates. In this paper, an approach based on Classical Lamination Theory ( CLT), combined with Finite Element Methods ( FEM), using Failure Analysis and Internal Load Redistribution, is utilised, in order to compare the behaviour of the material under specific loads. The main goal is to analyse the deformability of certain types of textile reinforced composite laminates, using carbon fibre satin as reinforcement and epoxy resin as matrix. This is accomplished by studying the variation of the in-plane strains, given the fluctuation of several geometric parameters, namely the width of the reinforcing tow, the gap between two consecutive tows, the angle of laminae in a multi-layered configuration and the tows fibre volume fraction.

  10. Insights into the Mechanical Behaviour of a Layered Flexible Tactile Sensor

    Directory of Open Access Journals (Sweden)

    Julián Castellanos-Ramos

    2015-10-01

    Full Text Available This paper shows realizations of a piezoresistive tactile sensor with a low cost screen-printing technology. A few samples were fabricated for different materials used as insulator between the conductive layers and as top layer or cover. Both can be used to tune the sensitivity of the sensor. However, a large influence is also observed of the roughness at the contact interface on the sensitivity and linearity of the output, as well as on mismatching between the outputs from different taxels. The roughness at the contact interface is behind the transduction principle of the sensor, but it also limits its performance if the wavelength of the roughness is comparable or even longer than the size of the contacts. The paper shows experimental results that confirm this relationship and discusses its consequences in sensor response related to the materials chosen for the insulator and the cover. Moreover, simulations with FEA tools and with simple models are used to support the discussions and conclusions obtained from the experimental data. This provides insights into the sensor behaviour that are shared by other sensors based on the same principle.

  11. Abnormal duodenal loop demonstrated by X-ray. Correlation to symptoms and prognosis of dyspepsia

    Energy Technology Data Exchange (ETDEWEB)

    Thommesen, P.; Funch-Jensen, P.

    1986-01-01

    The occurrence of dyspeptic symptoms has previously been correlated with the shape of the duodenal loop in patients with X-ray-negative dyspepsia. An abnormal duodenal loop was associated with a significantly higher incidence of symtoms provoked by meals, vomiting, regurgitations, heartburn, and the irritable bowel syndrome. 89% of these patients (26 patients with a normal duodenal loop and 39 patients with abnormal duodenal loop) were available for a 5-year follow-up study of symptomatic outcome. The incidence of symptoms provoked by meals was still significantly higher in patients with an abnormal duodenal loop, and there was also a significant difference concerning symptomatic outcome. Approximately 75% of the patients with a normal duodenal loop had improved, and 25% had unchanged clinical conditions. Approximately 50% of the patients with an abnormal duodenal loop had improved, and 50% had an unchanged or even deteriorated clinical condition.

  12. Endoscopic treatment of sporadic small duodenal and ampullary neuroendocrine tumors.

    Science.gov (United States)

    Gincul, Rodica; Ponchon, Thierry; Napoleon, Bertrand; Scoazec, Jean-Yves; Guillaud, Olivier; Saurin, Jean-Christophe; Ciocirlan, Mihai; Lepilliez, Vincent; Pioche, Mathieu; Lefort, Christine; Adham, Mustapha; Pialat, Jean; Chayvialle, Jean-Alain; Walter, Thomas

    2016-11-01

    Background and study aim: As duodenal neuroendocrine tumors (NETs) are rare, their optimal management has not been clearly established. The aim of this study was to evaluate the feasibility and outcome of endoscopic treatment of duodenal NETs. Patients and methods: We reviewed the files of all patients who underwent endoscopic resection of a sporadic duodenal or ampullary NET between 1996 and 2014 at two centers. Results: A total of 29 patients with 32 uT1N0M0 NETs < 20 mm were included. Treatment consisted of endoscopic mucosal resection in 19 cases, and cap aspiration in 13 cases. Prior submucosal saline injection was used in 15 cases. Mortality was 3 % (one severe bleeding). Morbidity was 38 % (11/29). At post-resection analysis, mean tumor size was 8.9 mm (range 3 - 17 mm), 29 lesions were stage pT1, one was pT2, and 2 were pTx because of piecemeal resection. All NETs were well differentiated. A total of 27 lesions were classified as grade 1 and 5 were grade 2. The resection was R0, R1, and Rx for 16, 14, and 2 lesions, respectively. Three R1 patients underwent additional surgical treatment, with no residual tumor on the surgical specimen but with positive metastatic lymph nodes in two cases. One patient was lost to follow-up. Finally, 24 patients were included in the follow-up analysis. The median follow-up period was 56 months (range 6 - 175 months). Two patients presented a tumor recurrence during the follow-up period. Conclusions: Endoscopic treatment of small duodenal NETs was associated with significant morbidity, a difficulty in obtaining an R0 specimen, and the risk of lymph node metastasis. Nevertheless, it represents an interesting alternative in small grade 1 duodenal lesions and in patients at high surgical risk.

  13. Loss of intestinal O-glycans promotes spontaneous duodenal tumors.

    Science.gov (United States)

    Gao, Nan; Bergstrom, Kirk; Fu, Jianxin; Xie, Biao; Chen, Weichang; Xia, Lijun

    2016-07-01

    Mucin-type O-glycans, primarily core 1- and core 3-derived O-glycans, are the major mucus barrier components throughout the gastrointestinal tract. Previous reports identified the biological role of O-glycans in the stomach and colon. However, the biological function of O-glycans in the small intestine remains unknown. Using mice lacking intestinal core 1- and core 3-derived O-glycans [intestinal epithelial cell C1galt1(-/-);C3GnT(-/-) or double knockout (DKO)], we found that loss of O-glycans predisposes DKO mice to spontaneous duodenal tumorigenesis by ∼1 yr of age. Tumor incidence did not increase with age; however, tumors advanced in aggressiveness by 20 mo. O-glycan deficiency was associated with reduced luminal mucus in DKO mice before tumor development. Altered intestinal epithelial homeostasis with enhanced baseline crypt proliferation characterizes these phenotypes as assayed by Ki67 staining. In addition, fluorescence in situ hybridization analysis reveals a significantly lower bacterial burden in the duodenum compared with the large intestine. This phenotype is not reduced with antibiotic treatment, implying O-glycosylation defects, rather than bacterial-induced inflammation, which causes spontaneous duodenal tumorigenesis. Moreover, inflammatory responses in DKO duodenal mucosa are mild as assayed with histology, quantitative PCR for inflammation-associated cytokines, and immunostaining for immune cells. Importantly, inducible deletion of intestinal O-glycans in adult mice leads to analogous spontaneous duodenal tumors, although with higher incidence and heightened severity compared with mice with O-glycans constitutive deletion. In conclusion, these studies reveal O-glycans within the small intestine are critical determinants of duodenal cancer risk. Future studies will provide insights into the pathogenesis in the general population and those at risk for this rare but deadly cancer.

  14. A study of the annealing and mechanical behaviour of electrodeposited Cu-Ni multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Pickup, C.J.

    1997-08-01

    The mechanical strength of electrodeposited Cu-Ni multilayers is known to vary with deposition wavelength. Since layered coatings are harder and more resistant to wear and abrasion than non-layered coatings, this technique is of industrial interest. Optimisation of the process requires a better understanding of the strengthening mechanisms and the microstructural changes which affect such mechanisms. The work presented in this thesis presents the characterisation a series of Cu-Ni multilayers, covering a wide range of thicknesses of the individual layers in the multilayer, using X-ray diffraction, cross-section TEM, hardness testing and tensile testing. Further, the effects of high temperature annealing on interdiffusion and on changes in internal stresses are documented. (au). 176 refs.

  15. Modeling of mechanical behaviour of HSLA low carbon bainitic steel thermomechanically processed

    Science.gov (United States)

    Santos, D. B.; Rodrigues, P. C. M.; Cota, A. B.

    2003-10-01

    A comparative study of the microstructure characterization and mechanical properties was done in a HSLA low carbon (0.08%) bainitic steel containing boron, developed by industry as a bainitic steel grade APIX80. The steel was submitted to two different thermomechanical processes. In the first one, controlled rolling followed by accelerated cooling was applied in laboratory mill. In the second processing, specimens of the same steel were submitted to hot torsion testing. The influence of cooling conditions like start cooling temperature, cooling rates and finish cooling temperature on the microstructure and mechanical properties were investigated. The final microstructure obtained was a complex mixture of polygonal ferrite, perlite, bainite and martensite/retained austenite constituent. The use of multiple regression analysis allowed the establishment of quantitative relationships between the accelerated cooling variables and mechanical properties of the steel available from Vickers microhardness and tensile tests.

  16. Thermo-Mechanical Behaviour of Turbine Disc Assembly in the Presence of Residual Stresses

    Science.gov (United States)

    Maricic, Luke Anthony

    A comprehensive three dimensional coupled thermo-mechanical finite element study is performed on turbine blade attachments in gas turbine engines. The effects of the self-generated centrifugal forces of the disc and the associated blades, thermal loads, and shot peening residual are all considered in this thesis. Three aspects of the work were accordingly examined. The first was concerned with the coupled thermo-mechanical stress analysis and load sharing between the teeth of the fir-tree root. The second was devoted to the development of a complete model incorporating the effect of shot peening residual stresses upon the developed stress state. The effectiveness of shot peening treatment in response to cyclic thermo-mechanical loadings at the contact interface has also been studied. The third was concerned with the validation of some aspects of the developed models analytically using closed form solutions and experimentally using photoelasticity.

  17. Optimising mechanical behaviour of new advanced steels based on fine non-equilibrium microstructures

    OpenAIRE

    HajyAkbary, F.

    2015-01-01

    This Ph.D. thesis investigates the relation between microstructural and mechanical properties of Advanced High Strength Steels (AHSS), with the goal of developing a microstructure with optimised mechanical properties. Among different grades of AHSS, Quenching and Partitioning (Q&P) steel which is composed of thin films of retained austenite between carbon depleted martensite laths, is selected. Different Q&P microstructures were developed in a 0.3C-1.6Si-3.5Mn (wt.%) steel with non-homogenous...

  18. Impaired nocifensive behaviours and mechanical hyperalgesia, but enhanced thermal allodynia in pituitary adenylate cyclase-activating polypeptide deficient mice.

    Science.gov (United States)

    Sándor, K; Kormos, V; Botz, B; Imreh, A; Bölcskei, K; Gaszner, B; Markovics, A; Szolcsányi, J; Shintani, N; Hashimoto, H; Baba, A; Reglodi, D; Helyes, Z

    2010-10-01

    Pituitary adenylate cyclase-activating polypeptide-38 (PACAP-38) and its receptors (PAC1 and VPAC) have been shown in the spinal dorsal horn, dorsal root ganglia and sensory nerve terminals. Data concerning the role of PACAP in central pain transmission are controversial and we have recently published its divergent peripheral effects on nociceptive processes. The aim of the present study was to investigate acute somatic and visceral nocifensive behaviours, partial sciatic nerve ligation-evoked chronic neuropathic, as well as resiniferatoxin-induced inflammatory thermal and mechanical hyperalgesia in PACAP deficient (PACAP(-/-)) mice to elucidate its overall function in pain transmission. Neuronal activation was investigated with c-Fos immunohistochemistry. Paw lickings in the early (0-5 min) and late (20-45 min) phases of the formalin test were markedly reduced in PACAP(-/-) mice. Acetic acid-evoked abdominal contractions referring to acute visceral chemonociception was also significantly attenuated in PACAP knockout animals. In both models, the excitatory role of PACAP was supported by markedly greater c-Fos expression in the periaqueductal grey and the somatosensory cortex. In PACAP-deficient animals neuropathic mechanical hyperalgesia was absent, while c-Fos immunopositivity 20 days after the operation was significantly higher. In this chronic model, these neurons are likely to indicate the activation of secondary inhibitory pathways. Intraplantarly injected resiniferatoxin-evoked mechanical hyperalgesia involving both peripheral and central processes was decreased, but thermal allodynia mediated by only peripheral mechanisms was increased in PACAP(-/-) mice. These data clearly demonstrate an overall excitatory role of PACAP in pain transmission originating from both exteroceptive and interoceptive areas, it is also involved in central sensitization. This can be explained by the signal transduction mechanisms of its identified receptors, both PAC1 and VPAC

  19. A combined microstructural and petrophysical study to analyse the mechanical behaviour of shales in the Flysch units, Glarus Alps, Switzerland

    Science.gov (United States)

    Akker, Vénice; Kaufmann, Josef; Berger, Alfons; Herwegh, Marco

    2017-04-01

    Crustal scale deformation is strongly controlled by the rheological behaviour of sheet-silicate-rich rock types. As these rocks have low rock strength, facilitated by the strong crystallographically controlled mechanical anisotropy and interstitial pore fluid in the aggregate, they are able to accommodate considerable amounts of strain. A close relationship is expected between microstructure, porosity and permeability as function of metamorphic conditions and strain gradients. Thereby, fluids set free by compaction, mineral reactions or deformation play an important role. Rising industries in underground storage such as nuclear waste disposal, shale gas exploration or geological carbon sequestration make use of the advantageous properties of such rock types. Therefore, there is a great demand for research on the interaction of these processes. This study uses samples from Flysch-units of the Glarus Alps (Switzerland) collected along a metamorphic gradient (150-400°C) to unravel the link between the mechanical behaviour of these sheet-silicate-rich rocks at geological conditions and their present-day physical parameters. Investigations include two topics: (1) characterization of such rock types in terms of mineralogy, microstructure and petrophysical properties; and (2) possible reconstruction of deformation processes from microstructures. Quantitative information on the porosity, i.e. the pore sizes, distribution and their interconnectivity is crucial for both topics. Porosity is therefore estimated by: (1) image analysis of high resolution SEM images, (2) He-pycnometry, and (3) Hg-porosimetry. In a first step, differences in their present day physical parameters between low and high temperature sampling sites are shown. The variations inside and between the investigated samples is partly due to initial sedimentological heterogeneity and partly to the changes along the metamorphic gradient. This study will demonstrate how the characterized present day porosity

  20. Effect of CO2-induced reactions on the mechanical behaviour of fractured wellbore cement

    NARCIS (Netherlands)

    Wolterbeek, T.K.T.; Hangx, S.J.T.; Spiers, C.J.

    2016-01-01

    Geomechanical damage, such as fracturing of wellbore cement, can severely impact well integrity in CO2 storage fields. Chemical reactions between the cement and CO2-bearing fluids may subsequently alter the cement’s mechanical properties, either enhancing or inhibiting damage accumulation during ong

  1. Using Formal Game Design Methods to Embed Learning Outcomes into Game Mechanics and Avoid Emergent Behaviour

    Science.gov (United States)

    Grey, Simon; Grey, David; Gordon, Neil; Purdy, Jon

    2017-01-01

    This paper offers an approach to designing game-based learning experiences inspired by the Mechanics-Dynamics-Aesthetics (MDA) model (Hunicke et al., 2004) and the elemental tetrad model (Schell, 2008) for game design. A case for game based learning as an active and social learning experience is presented including arguments from both teachers and…

  2. MECHANICAL BEHAVIOUR OF ABACA-GLASS-BANANA FIBRE REINFORCED HYBRID COMPOSITES

    Directory of Open Access Journals (Sweden)

    H. VENKATASUBRAMANIAN

    2015-08-01

    Full Text Available Hybrid composites comprising of natural and synthetic fibres with phenolic resin is one of the present composite manufacturing techniques for achieving enhanced mechanical properties. In this study Abaca-banana-glass composites has been fabricated and its mechanical properties were analysed. Tensile, flexural and impact strength were investigated in the process of mechanical characterisation. Matrix material used is a phenolic resin of Ortho-Phthalic acid. The manufacture of the composite is done by hand layup technique where the fibre content is varied through volume fraction of 0.4 to 0.5. Setup is arranged in such a way that glass fibre is arranged on the top and bottom layers of the laminate which adds up strength and produces a better surface finish, where in the natural fibre is sandwiched in intermediate layers within the glass fibre. Fibre orientation and the detailed internal structure of matrix were studied by using SEM photography. The results showed that Abaca-banana-glass hybrid composite has better tensile property, Banana-glass composite has the best flexural property and Abaca-glass composite has the best impact property. The results obtained show a substantial increase in mechanical properties and hence these hybrid composites can be used as an effective alternative for synthetic fibres and can be used as an alternate for different industrial application.

  3. Viscoelastic behaviour of hydrogel-based composites for tissue engineering under mechanical load.

    Science.gov (United States)

    Kocen, Rok; Gasik, Michael; Gantar, Ana; Novak, Saša

    2017-03-06

    Along with biocompatibility, bioinductivity and appropriate biodegradation, mechanical properties are also of crucial importance for tissue engineering scaffolds. Hydrogels, such as gellan gum (GG), are usually soft materials, which may benefit from the incorporation of inorganic particles, e.g. bioactive glass, not only due to the acquired bioactivity, but also due to improved mechanical properties. They exhibit complex viscoelastic properties, which can be evaluated in various ways. In this work, to reliably evaluate the effect of the bioactive glass (BAG) addition on viscoelastic properties of the composite hydrogel, we employed and compared the three most commonly used techniques, analyzing their advantages and limitations: monotonic uniaxial unconfined compression, small amplitude oscillatory shear (SAOS) rheology and dynamic mechanical analysis (DMA). Creep and small amplitude dynamic strain-controlled tests in DMA are suggested as the best ways for the characterization of mechanical properties of hydrogel composites, whereas the SAOS rheology is more useful for studying the hydrogel's processing kinetics, as it does not induce volumetric changes even at very high strains. Overall, the results confirmed a beneficial effect of BAG (nano)particles on the elastic modulus of the GG-BAG composite hydrogel. The Young's modulus of 6.6 ± 0.8 kPa for the GG hydrogel increased by two orders of magnitude after the addition of 2 wt.% BAG particles (500-800 kPa).

  4. Mechanical behaviour of degradable phosphate glass fibres and composites-a review.

    Science.gov (United States)

    Colquhoun, R; Tanner, K E

    2015-12-23

    Biodegradable materials are potentially an advantageous alternative to the traditional metallic fracture fixation devices used in the reconstruction of bone tissue defects. This is due to the occurrence of stress shielding in the surrounding bone tissue that arises from the absence of mechanical stimulus to the regenerating bone due to the mismatch between the elastic modulus of bone and the metal implant. However although degradable polymers may alleviate such issues, these inert materials possess insufficient mechanical properties to be considered as a suitable alternative to current metallic devices at sites of sufficient mechanical loading. Phosphate based glasses are an advantageous group of materials for tissue regenerative applications due to their ability to completely degrade in vivo at highly controllable rates based on the specific glass composition. Furthermore the release of the glass's constituent ions can evoke a therapeutic stimulus in vivo (i.e. osteoinduction) whilst also generating a bioactive response. The processing of these materials into fibres subsequently allows them to act as reinforcing agents in degradable polymers to simultaneously increase its mechanical properties and enhance its in vivo response. However despite the various review articles relating to the compositional influences of different phosphate glass systems, there has been limited work summarising the mechanical properties of different phosphate based glass fibres and their subsequent incorporation as a reinforcing agent in degradable composite materials. As a result, this review article examines the compositional influences behind the development of different phosphate based glass fibre compositions intended as composite reinforcing agents along with an analysis of different potential composite configurations. This includes variations in the fibre content, matrix material and fibre architecture as well as other novel composites designs.

  5. Hydro mechanical coupling for non linear behaviour laws. Application to petroleum problems; Couplage hydromecanique pour des lois de comportement non lineaires Application a des problemes petroliers

    Energy Technology Data Exchange (ETDEWEB)

    Longuemare, P.

    1996-11-28

    The aim of this study is to provide a better description of the rock contribution to fluid flows in sedimentary basins and petroleum reservoirs. After a study of the mechanical behaviour of high porosity chalks and shales, we present the elaboration of an elastoplastic constitutive model for the description of their behaviour under various strain and stress paths. This model is introduced in a coupled poro-mechanical approach and used to study the advantages of a good description of strain and stress paths in petroleum reservoirs and sedimentary basins studies. Hydro-mechanical modelling of the behaviour of petroleum reservoir allowed us to analyse the influence of boundary limit conditions on stress paths recovery rates. The study of sedimentary basins showed the importance of the consideration of the evolution of the porosity with time due to the time-scale difference between the laboratory and the field data. (author) 58 refs.

  6. Mechanical and cold hypersensitivity in nerve-injured C57BL/6J mice is not associated with fear-avoidance- and depression-related behaviour.

    Science.gov (United States)

    Hasnie, F S; Wallace, V C J; Hefner, K; Holmes, A; Rice, A S C

    2007-06-01

    Neuropathic pain is associated with significant co-morbidity, including anxiety and depression, which impact considerably on the overall patient experience. However, pain co-morbidity symptoms are rarely assessed in animal models of neuropathic pain. To improve the clinical validity of a widely used rodent model of traumatic peripheral neuropathy, we have investigated fear-avoidance- and depression-related behaviours in nerve-injured and sham-operated mice over a 4 week period. Male C57BL/6J mice were subjected to partial sciatic nerve ligation (PSNL) or sham surgery and were assessed on days 7, 14, and 28 after operation. Withdrawal thresholds to punctate mechanical and cooling stimuli were measured. Mice were tested on the novel open-field and elevated plus-maze tests for fear-avoidance behaviour, and on the tail suspension test for depression-related behaviour. Hypersensitivity to punctate mechanical and cool stimuli was evident up to day 28 after PSNL. However, there was no change in fear-avoidance- or depression-related behaviours regardless of interval after-surgery. These data demonstrate that pain behaviour in nerve-injured C57BL/6J mice was not associated with alterations in emotion-related behaviours.

  7. Mechanical behaviour of pressed and sintered titanium alloys obtained from prealloyed and blended elemental powders.

    Science.gov (United States)

    Bolzoni, L; Esteban, P G; Ruiz-Navas, E M; Gordo, E

    2012-10-01

    The applicability of irregular prealloyed Ti-6Al-4V powder for the fabrication of titanium products by pressing and sintering and its employment as a master alloy to obtain the Ti-3Al-2.5V alloy was studied. To this end, the starting powders were characterised by dilatometry, differential thermal analysis and XRD. Green samples were obtained by cold uniaxial pressing, and the evolution of the microstructure over the sintering temperature range 900-1400°C was studied. The variation of the final density and mechanical properties with the sintering temperature was considered. Based on the study carried out, it can be stated that more reliable powders are needed to open the titanium market to new applications. A relative density of 95% and diverse microstructural features and mechanical properties equivalent to those of biomedical devices can be obtained by the pressing and sintering route.

  8. Wear Behaviour of A356/TiAl3 in Situ Composites Produced by Mechanical Alloying

    Directory of Open Access Journals (Sweden)

    Seda Çam

    2016-02-01

    Full Text Available In this study, the effects of in situ TiAl3 particles on dry sliding wear behavior of A356 aluminum alloy (added Ti composites were investigated. The wear samples were prepared by adding different amounts of Ti (4%, 6%, and 8% into A356 powder alloy by mechanical alloying. The mechanically alloyed powders were cold pressed at 600 MPa and sintered 530 °C for 1 h in argon atmosphere and cooled in the furnace. After the sintering process, the samples were characterized. The results show that AlTi and TiAl3 intermetallic phases were formed and their amount increased depending on the amount of Ti added into A356 powder alloy. Out of the samples sintered with different titanium amounts (1 h at 530 °C, the highest hardness value and, accordingly, the lowest wear amount, were observed in the alloy containing 8% Ti.

  9. Impact behaviour of nylon-rubber blends: 5. Influence of the mechanical properties of the elastomer

    OpenAIRE

    Borggreve, R.J.M.; Gaymans, R.J.; Schuijer, J.

    1989-01-01

    Blends of 90wt% nylon-6 and 10wt% impact modifier were prepared. As impact modifiers were used: EPDM (ethylene propylene diene monomer) rubber, EPM (ethylene propylene monomer) rubber, polyethylene, four poly(ether esters) and some commercial impact modifers. EPDM, EPM and polyethylene were functionalized with maleic anhydride. The mechanical properties of the impact modifiers were tested with both a torsion pendulum test and a tensile test. The notched impact strength of the blends was measu...

  10. The mechanical and microstructural behaviour of calcite-dolomite composites: An experimental investigation

    OpenAIRE

    Kushnir, Alexandra R. l.; Kennedy, L. A.; Misra, Santanu; Benson, Philip; White, J C

    2015-01-01

    The styles and mechanisms of deformation associated with many variably dolomitized limestone shear systems are strongly controlled by strain partitioning between dolomite and calcite. Here, we present experimental results from the deformation of four composite materials designed to address the role of dolomite on the strength of limestone. Composites were synthesized by hot isostatic pressing mixtures of dolomite (Dm) and calcite powders (% Dm: 25%-Dm, 35%-Dm, 51%-Dm, and 75%-Dm). In all comp...

  11. Thermo-mechanical behaviour of heavy-duty disc brake systems

    OpenAIRE

    Chen, J. P.

    2001-01-01

    In heavy-duty disc brake systems, braking is a transient, non-linear and asymmetrical thermo-mechanical process. Surface cracking, rather than wear, is the major factor limiting the brake disc's life. The disc material (cast-iron), heat transfer boundary conditions and pad-disc frictional reactions are characteristically non-linear and asymmetrical during the friction process. Non-uniform deformation and surface cracks in brake discs result from the accumulation of excess...

  12. Characterization and corrosion behaviour of CoNi alloys obtained by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Olvera, S. [Instituto Politécnico Nacional, ESIQIE, Departamento de Ingeniería en Metalurgia y Materiales, México, D. F. (Mexico); Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química-Física Aplicada, 28049 Madrid (Spain); Sánchez-Marcos, J. [Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química-Física Aplicada, 28049 Madrid (Spain); Palomares, F.J. [Instituto de Ciencia de Materiales de Madrid, ICMM-CSIC, Cantoblanco, 28049 Madrid (Spain); Salas, E. [Spline Spanish CRG Beamline at the European Synchrotron Radiation Facilities, ESRF, BP 220-38043, Grenoble Cedex (France); Arce, E.M. [Instituto Politécnico Nacional, ESIQIE, Departamento de Ingeniería en Metalurgia y Materiales, México, D. F. (Mexico); Herrasti, P., E-mail: pilar.herrasti@uam.es [Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química-Física Aplicada, 28049 Madrid (Spain)

    2014-07-01

    CoNi alloys including Co{sub 30}Ni{sub 70}, Co{sub 50}Ni{sub 50} and Co{sub 70}Ni{sub 30} were prepared via mechanical alloying using Co and Ni powders. The crystallinity and short-range order were studied using X-ray diffraction and X-ray absorption spectroscopy. The results show that the milling process increases the number of vacancies, especially around the Co atoms, while the milling time decreases the crystalline size and enhances the crystallinity. X-ray photoelectron spectroscopy was used to characterise the chemical composition of the samples surface. The magnetic properties were analysed using zero-field cooling, field cooling and a magnetic hysteresis loops. The magnetic saturation moment is approximately 1.05 μ{sub B}/atom; this value decreases with the mechanical alloying time, and it is proportional to the cobalt concentration. The polarization and impedance curves in different media (NaCl, H{sub 2}SO{sub 4} and NaOH) showed similar corrosion resistance values. The corrosion resistance increased in the order NaCl, H{sub 2}SO{sub 4} and NaOH. A good passivation layer was formed in NaOH due to the cobalt and nickel oxides on the particle surfaces. - Highlights: • Ni{sub x}Co{sub 100-x} alloys were synthesized by mechanical alloying • Milling time decrease size and enhances crystallinity. • Oxygen is not present in a significant percentage in bulk but is detected on the surface. • Magnetic saturation moment is 1.05 mB/atom and decrease with mechanical allowing time • Corrosion resistance is higher in NaOH than in NaCl or HCl solutions.

  13. New methodology for mechanical characterization of human superficial facial tissue anisotropic behaviour in vivo.

    Science.gov (United States)

    Then, C; Stassen, B; Depta, K; Silber, G

    2017-02-21

    Mechanical characterization of human superficial facial tissue has important applications in biomedical science, computer assisted forensics, graphics, and consumer goods development. Specifically, the latter may include facial hair removal devices. Predictive accuracy of numerical models and their ability to elucidate biomechanically relevant questions depends on the acquisition of experimental data and mechanical tissue behavior representation. Anisotropic viscoelastic behavioral characterization of human facial tissue, deformed in vivo with finite strain, however, is sparse. Employing an experimental-numerical approach, a procedure is presented to evaluate multidirectional tensile properties of superficial tissue layers of the face in vivo. Specifically, in addition to stress relaxation, displacement-controlled multi-step ramp-and-hold protocols were performed to separate elastic from inelastic properties. For numerical representation, an anisotropic hyperelastic material model in conjunction with a time domain linear viscoelasticity formulation with Prony series was employed. Model parameters were inversely derived, employing finite element models, using multi-criteria optimization. The methodology provides insight into mechanical superficial facial tissue properties. Experimental data shows pronounced anisotropy, especially with large strain. The stress relaxation rate does not depend on the loading direction, but is strain-dependent. Preconditioning eliminates equilibrium hysteresis effects and leads to stress-strain repeatability. In the preconditioned state tissue stiffness and hysteresis insensitivity to strain rate in the applied range is evident. The employed material model fits the nonlinear anisotropic elastic results and the viscoelasticity model reasonably reproduces time-dependent results. Inversely deduced maximum anisotropic long-term shear modulus of linear elasticity is G∞,max(aniso)=2.43kPa and instantaneous initial shear modulus at an

  14. Bioactivity and mechanical behaviour of cobalt oxide-doped bioactive glass

    Indian Academy of Sciences (India)

    Vikash Kumar Vyas; Arepalli Sampath Kumar; Sunil Prasad; S P Singh; Ram Pyare

    2015-08-01

    Bioactive glasses are materials capable of bonding implants to tissues. 45S5 Bio-glass® is one such material capable of bonding strongly to bone within 6 weeks. It develops a hydroxy-carbonate apatite layer on the implant that is chemically and crystallographically equivalent to the mineral phase of bone. However, it suffers from a mechanical weakness and low fracture toughness due to an amorphous glass network and is not suitable for load-bearing applications. In order to improve its mechanical strength and bioactivity, the present work explores the effects of cobalt oxide additions. Bioactivity of the glass samples was assessed through their hydroxyapatite formation ability by immersing them in the simulated body fluid for different soaking periods. The formation of hydroxyapatite was confirmed by Fourier transform infrared spectrometry, pH measurement and microstructure evaluation through scanning electron microscopy. Densities and mechanical properties of the samples were found to increase considerably with an increase in the concentration of cobalt oxide.

  15. Sintering behaviour and mechanical properties of Cr3C2–NiCr cermets

    Indian Academy of Sciences (India)

    A Özer; Y K Tür

    2013-10-01

    Cr3C2–NiCr cermets are used as metal cutting tools due to their relatively high hardness and low sintering temperatures. In this study, a powder mixture consisting of 75 wt% Cr3C2–25 wt% NiCr was sintered at four different temperatures and characterized for itsmicrostructure and mechanical properties. The highest relative density obtained was 97% when sintered at 1350 °C. As the relative density increased, elastic modulus, transverse rupture strength, fracture toughness and hardness of the samples reached to a maximum of 314 GPa, 810 MPa, 10.4 MPa.m1/2 and 11.3 GPa, respectively. However, sintering at 1400 °C caused further grain growth and pore coalescence which resulted in decreasing density and degradation of all mechanical properties. Fracture surface investigation showed that the main failure mechanism was the intergranular fracture of ceramic phase accompanied by the ductile fracture of the metal phase which deformed plastically during crack propagation and enhanced the fracture toughness.

  16. Water Absorption Behaviour and Its Effect on the Mechanical Properties of Flax Fibre Reinforced Bioepoxy Composites

    Directory of Open Access Journals (Sweden)

    E. Muñoz

    2015-01-01

    Full Text Available In the context of sustainable development, considerable interest is being shown in the use of natural fibres like as reinforcement in polymer composites and in the development of resins from renewable resources. This paper focuses on eco-friendly and sustainable green composites manufacturing using resin transfer moulding (RTM process. Flax fibre reinforced bioepoxy composites at different weight fractions (40 and 55 wt% were prepared in order to study the effect of water absorption on their mechanical properties. Water absorption test was carried out by immersion specimens in water bath at room temperature for a time duration. The process of water absorption of these composites was found to approach Fickian diffusion behavior. Diffusion coefficients and maximum water uptake values were evaluated; the results showed that both increased with an increase in fibre content. Tensile and flexural properties of water immersed specimens were evaluated and compared to dry composite specimens. The results suggest that swelling of flax fibres due to water absorption can have positive effects on mechanical properties of the composite material. The results of this study showed that RTM process could be used to manufacture natural fibre reinforced composites with good mechanical properties even for potential applications in a humid environment.

  17. Mechanical behaviour of the Oman metamorphic sole: rheology of amphibolites at lower crustal conditions during subduction initiation

    Science.gov (United States)

    Soret, Mathieu; Agard, Philippe; Ildefonse, Benoît; Dubacq, Benoît; Prigent, Cécile; Yamato, Philippe

    2017-04-01

    Amphibolites are commonly found in the middle to lower continental crust and along oceanic transform faults and detachments. Amphibolites are also the main component of metamorphic soles beneath highly strained peridotites at the base of large-scale ophiolites as exemplified in Oman. Metamorphic soles are crustal slivers stripped from the slab during early subduction and underplated below the upper plate (future ophiolite) mantle when the subduction interface is still young and warm (i.e. during the first million years -My- of intra-oceanic subduction). Understanding the rheological behaviour of amphibolitic rocks is therefore of major interest to model and quantify deformation and strain localisation in varied geodynamical environments. This contribution focuses on the deformation mechanisms of amphibole through a microstructural and petrological study of garnet-bearing and garnet-free clinopyroxene-bearing amphibolites, using EBSD analysis. The first aim is to test the influence of progres- sive changes in PT conditions during deformation and of the appearance/disappearance of anhydrous minerals (plagioclase, clinopyroxene and garnet) on the mechanical behaviour of mafic amphibolites. The second aim is to track deformation mechanisms during early subduction, through the study of these metamorphosed oceanic rocks, commonly 10-100 m thick, which range from high- to low-grade away from the contact with the peridotites (i.e. from 800 ± 100˚C - 0.9 ± 0.2 GPa to 500 ± 100˚C - 0.5 ± 0.1 GPa) and are essentially mafic at the top). Our study points out the existence of two major steps of deformation in the high-temperature amphibolite slices of the metamorphic soles during the early subdduction dynamics. These two steps witness important mechanical coupling and progressive strain localization at plate interface under cooling and hydrated conditions after subduction initiation. During the accretion of the first slice of metamorphic sole at 850 ± 50˚C (the garnet

  18. Composite model to reproduce the mechanical behaviour of methane hydrate bearing soils

    Science.gov (United States)

    De la Fuente, Maria

    2016-04-01

    Methane hydrate bearing sediments (MHBS) are naturally-occurring materials containing different components in the pores that may suffer phase changes under relative small temperature and pressure variations for conditions typically prevailing a few hundreds of meters below sea level. Their modelling needs to account for heat and mass balance equations of the different components, and several strategies already exist to combine them (e.g., Rutqvist & Moridis, 2009; Sánchez et al. 2014). These equations have to be completed by restrictions and constitutive laws reproducing the phenomenology of heat and fluid flows, phase change conditions and mechanical response. While the formulation of the non-mechanical laws generally includes explicitly the mass fraction of methane in each phase, which allows for a natural update of parameters during phase changes, mechanical laws are, in most cases, stated for the whole solid skeleton (Uchida et al., 2012; Soga et al. 2006). In this paper, a mechanical model is proposed to cope with the response of MHBS. It is based on a composite approach that allows defining the thermo-hydro-mechanical response of mineral skeleton and solid hydrates independently. The global stress-strain-temperature response of the solid phase (grains + hydrate) is then obtained by combining both responses according to energy principle following the work by Pinyol et al. (2007). In this way, dissociation of MH can be assessed on the basis of the stress state and temperature prevailing locally within the hydrate component. Besides, its structuring effect is naturally accounted for by the model according to patterns of MH inclusions within soil pores. This paper describes the fundamental hypothesis behind the model and its formulation. Its performance is assessed by comparison with laboratory data presented in the literature. An analysis of MHBS response to several stress-temperature paths representing potential field cases is finally presented. References

  19. CISM course on mechanical behaviour of soils under environmentally induced cyclic loads

    CERN Document Server

    Wood, David; Mechanical Behaviour of Soils Under Environmentally Induced Cyclic Loads

    2012-01-01

    The book gives a comprehensive description of the mechanical response of soils (granular and cohesive materials) under cyclic loading. It provides the geotechnical engineer with the theoretical and analytical tools necessary for the evaluation of settlements developng with time under cyclic, einvironmentally idncued loads (such as wave motion, wind actions, water table level variation) and their consequences for the serviceability and durability of structures such as the shallow or deep foundations used in offshore engineering, caisson beakwaters, ballast and airport pavements and also to interpret monitoring data, obtained from both natural and artificial slopes and earth embankments, for the purposes of risk assessment and mitigation.

  20. Influence of nickel addition on magnetic and electro-mechanical behaviour of permalloys

    Indian Academy of Sciences (India)

    Kiran Gupta; K K Raina; S K Sinha

    2006-08-01

    Magnetic and electro-mechanical investigations have been carried out in two Ni–Fe permalloys under hydrogen atmosphere by varying annealing temperature. These alloys have been characterized for various magnetic parameters like peak permeability, coercivity and core loss under changed annealing profile conditions. The magnetic properties of Ni-rich (Ni ∼ 82%) alloy at 100 Hz were found to be better than the low Ni (Ni ∼ 47%) alloy. The alloys were tested for watch movement and found that the battery life of the watch movement improved by 38% using Ni-rich permalloy.

  1. Geometrical and material parameters to assess the macroscopic mechanical behaviour of fresh cranial bone samples

    OpenAIRE

    AUPERRIN, Audrey; Delille, Rémi; LESUEUR, Denis; BRUYERE, Karine; Masson, Catherine; Drazetic, Pascal

    2014-01-01

    The present study aims at providing quantitative data for the personalisation of geometrical and 21 mechanical characteristics of the adult cranial bone to be applied to head FE models. A set of 351 22 cranial bone samples, harvested from 21 human skulls, were submitted to three-point bending tests 23 at 10 mm/min. For each of them, an apparent elastic modulus was calculated using the beam's 24 theory and a density-dependant beam inertia. Thicknesses, apparent densities and percentage of ash ...

  2. Experimental testing of the sorption-mechanical coupled behaviour of polyethylene into pressurized hydrogen

    Directory of Open Access Journals (Sweden)

    Comyn M.

    2010-06-01

    Full Text Available Coupling between pressurized gas sorption and tensile behavior was studied in a polyethylene (PE. Tensile and creep tests into hydrogen (30 bars and nitrogen (30 bars atmosphere were compared to experiments into atmospheric air. Gaseous environment was shown to have noticeable influence neither on the modulus / yield stress in tension, nor on the long term creep behavior. Mechanical consequence of a long term aging into hydrogen atmosphere was also investigated in samples previously exposed to hydrogen at various aging conditions (temperature, pressure, duration. No deleterious effect on the tensile properties of PE was evidenced.

  3. Mechanical and corrosion behaviour of EUROFER 97 steel exposed to Pb-17Li

    Energy Technology Data Exchange (ETDEWEB)

    Benamati, G.; Fazio, C. E-mail: concetta@brasimone.enea.it; Ricapito, I

    2002-12-01

    Corrosion and tensile samples of the EUROFER 97 steel were exposed to Pb-17Li in the LIFUS II loop at 480 deg. C. The specimens were extracted after 1500, 3000 and 4500 h exposure. After extraction, weight change measurements and metallurgical analysis were performed on the corrosion specimens, while tensile tests were performed at 480 deg. C. The results showed that EUROFER 97 underwent uniform corrosion and the mechanical properties seem to be unaffected or only slightly affected by the liquid metal. In this paper, the results are reported and discussed also with reference to previous similar work.

  4. EFFECT OF CLIMATIC FACTOR ON THE MECHANICAL BEHAVIOUR OF AEOLIAN BLADES: APPLICATION OF HYBRID COMPOSITE MATERIALS

    Directory of Open Access Journals (Sweden)

    F. Mili

    2015-08-01

    Full Text Available The great interest which the wind power brings in the development of the various economic sectors encourages to contribute in the improvement of the hydrothermal and mechanical performances of the blades of wind rotors with horizontal axis. The use of composite materials involves a profit of substantial weight, strength to the directional constraints that the blade will undergo during its work and a reduction of the aerodynamic and mechanical losses. The adoption of composite materials with unidirectional reinforcement carbon/epoxy makes it possible to get for the structure a high wear resistance and a reduction of the phenomenon of bearing pressure created around the airfoil of the blade moving relative compared to the speed of the wind. The evaluation of the behavior of such composites with [+θ/- θ]4S stacking sequence, with the combined effect of the temperature, the moisture and the tensile effort constitutes the principal axis of this contribution. In order to minimize the costs, our analysis will direct towards hybrid composite materials glass-carbon/epoxy being presented in the form of symmetrical laminates [+q/0°]2S and antisymmetric [+q/0°/90°/-q]. The results obtained showed that their use contributes to the improvement of their thermomechanical behavior by involving profits of performance, weight, cost savings and energy.

  5. Dynamic Mechanical Analysis and Three-Body Abrasive Wear Behaviour of Thermoplastic Copolyester Elastomer Composites

    Directory of Open Access Journals (Sweden)

    Hemanth Rajashekaraiah

    2014-01-01

    Full Text Available Various amounts of short fibers (glass and carbon and particulate fillers like polytetrafluoroethylene (PTFE, silicon carbide (SiC, and alumina (Al2O3 were systematically introduced into the thermoplastic copolyester elastomer (TCE matrix for reinforcement purpose. The mechanical properties such as storage modulus, loss modulus, and Tan δ by dynamic mechanical analysis (DMA and three-body abrasive wear performance on a dry sand rubber wheel abrasion tester have been investigated. For abrasive wear study, the experiments were planned according to L27 orthogonal array by considering three factors and three levels. The complex moduli for TCE hybrid composites were pushed to a higher level relative to the TCE filled PTFE composite. At lower temperatures (in the glassy region, the storage modulus increases with increase in wt.% of reinforcement (fiber + fillers and the value is maximum for the composite with 40 wt.% reinforcement. The loss modulus and damping peaks were also found to be higher by the incorporation of SiC and Al2O3 microfillers. The routine abrasive wear test results indicated that TCE filled PTFE composite exhibited better abrasion resistance. Improvements in the abrasion resistance, however, have not been achieved by short-fiber and particlaute filler reinforcements. From the Taguchi’s experimental findings, optimal combination of control factors were obtained for minimum wear volume and also predictive correlations were proposed. Further, the worn surface morphology of the samples was discussed.

  6. Effect of composition on mechanical behaviour of diamond-like carbon coatings modified with titanium

    Energy Technology Data Exchange (ETDEWEB)

    Caschera, D., E-mail: daniela.caschera@ismn.cnr.i [Institute for the Study of Nanostructured Materials, ISMN - CNR, P.O. Box 10, 00015 Monterotondo Stazione (Italy); Federici, F.; Pandolfi, L.; Kaciulis, S. [Institute for the Study of Nanostructured Materials, ISMN - CNR, P.O. Box 10, 00015 Monterotondo Stazione (Italy); Sebastiani, M.; Bemporad, E. [Dip.to di Ingegneria Industriale e Meccanica, Universita di Roma Tre, Via Vasca Navale 84, 00146 Roma (Italy); Padeletti, G. [Institute for the Study of Nanostructured Materials, ISMN - CNR, P.O. Box 10, 00015 Monterotondo Stazione (Italy)

    2011-03-01

    In this study, diamond-like carbon (DLC) films modified with titanium were deposited by plasma decomposition of metallorganic precursor, titanium isopropoxide in CH{sub 4}/H{sub 2}/Ar gas atmosphere. The obtained films were composed of amorphous titanium oxide and nanocrystalline titanium carbide, embedded in an amorphous hydrogenated (a-C:H) matrix. The TiC/TiO{sub 2} ratio in the DLC matrix was found to be dependent on the deposition parameters. The dependence of the films chemical composition on gas mixture and substrate temperature was investigated by X-ray photoelectron spectroscopy, whereas the crystallinity of TiC nanoparticles and their dimension were evaluated by X-ray diffraction. The size of TiC crystallites varied from 10 to 35 nm, depending on the process parameters. The intrinsic hardness of 10-13 GPa, elastic modulus of 170-200 GPa and hardness-to-modulus ratio of obtained coatings were measured by the nanoindentation technique. Obtained results demonstrated a correlation of mechanical properties with the chemical composition and the ratio of amorphous/crystalline phases in the films. In particular, the formation of nanocrystalline TiC with atomic concentration not exceeding 10% and with grain size between 10 nm and 15 nm resulted in significantly enhanced mechanical properties of composite material in comparison with ordinary DLC films.

  7. Microstructural evolution and mechanical behaviour of surface hardened low carbon hot rolled steel

    Energy Technology Data Exchange (ETDEWEB)

    Tewary, N.K. [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur, Howrah 711103 (India); Syed, B. [R and D Division, Tata Steel Limited, Jamshedpur 831007 (India); Ghosh, S.K., E-mail: skghosh@metal.becs.ac.in [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur, Howrah 711103 (India); Kundu, S. [R and D Division, Tata Steel Limited, Jamshedpur 831007 (India); Shariff, S.M.; Padmanabham, G. [Centre for Laser Processing, ARCI-Hyderabad, Balapur PO, AP 500005 (India)

    2014-06-01

    Surface hardening of low carbon hot rolled C–Mn steel has been successfully performed by high power diode laser with an achievable case depth of about 300 μm. The laser treated samples have been characterised using optical microscope, scanning electron microscope, transmission electron microscope, and X-ray diffraction techniques. Higher hardness level is achieved in laser surface hardened zone (≈300 HV) than in the base alloy region (≈140 HV). The variation in hardness as a function of distance across the laser tracks is observed during multi-track laser hardening. Laser hardened steel sheets show enhanced mechanical strength (YS: 383–443 MPa, UTS: 476–506 MPa) with the lowering of percentage total elongation (23–28%) compared to the base alloy (YS: 351 MPa, UTS: 450 MPa and total elongation is 32%). Strain hardening exponent (‘n’) has been evaluated from true tensile stress–strain diagram and it shows a similar nature for both base alloy and laser treated steels. The microstructure in the base alloy region consists of a mixture of ferrite and pearlite, whereas predominantly lath martensite is present in the laser hardened surface layer. The improvement of mechanical strength is discussed in terms of the formation of this hardened layer on the surface.

  8. The influence of the masonry mechanical properties in the structural behaviour of the Leon`s cathedral

    Directory of Open Access Journals (Sweden)

    Gálvez Ruiz, J. C.

    2009-06-01

    Full Text Available Mechanical and physical properties of the masonry have a considerable bearing on the structural behaviour. Ancient buildings, like Leon’s cathedral, show uncertainty about real condition of the material and even structural compounds. These uncertainties make it difficult to assessment the bearing capacity of the structure and the affect of the restorations. This paper shows a study to select the most influential material’s parameters on the structural behaviour. The study is based on a sensitiveness analysis.The study starts with a structural analysis to select the most responsible areas of the transversal structural section. Then, the structural calculation is done by modifying the value of the material’s parameters in the expected scatter band. The statistical study provides the most influential parameters on the structural masonry behaviour. Finally the conclusions are proponed.Las propiedades de un material como la fábrica influyen de forma determinante en el comportamiento de la estructura. En una estructura histórica, como la catedral de León, se añade la incertidumbre del estado real del material y la composición de sus elementos estructurales. Estos aspectos dificultan la evaluación de la capacidad resistente de la estructura y la incidencia de actuaciones de reparación o remodelación. Este trabajo presenta el estudio realizado para seleccionar, mediante un análisis de sensibilidad del comportamiento de la estructura, cuáles son las variables del material que más afectan al comportamiento estructural de la catedral.El estudio se inicia con el análisis estructural de la sección tipo para identificar las zonas de mayor responsabilidad. A continuación se hace el estudio estructural con la combinación de todas las variables, especialmente las dependientes de los materiales, modificando su valor. Mediante un tratamiento estadístico de los resultados, se determina qué parámetros de los adoptados afectan más al

  9. Towards mosquito sterile insect technique programmes: exploring genetic, molecular, mechanical and behavioural methods of sex separation in mosquitoes.

    Science.gov (United States)

    Gilles, Jeremie R L; Schetelig, Marc F; Scolari, Francesca; Marec, František; Capurro, Margareth L; Franz, Gerald; Bourtzis, Kostas

    2014-04-01

    When considering a mosquito release programme, one of the first issues to be addressed is how to eliminate/separate the females. The greatest number of options might eventually be available for those who can use transgenic mosquitoes, but the inherent characteristics of the target species may also provide possibilities for interim measures until more efficient methods can be developed. Differences in intrinsic size, in behaviour and in development rate between females and males are often available and useful for sexing. Efficient species-specific systems for eliminating females at the embryo stage have been developed, but most have since been discarded due to lack of use. Ideal systems specifically kill female embryos using some treatment that can be manipulated during production. Such killing systems are far more efficient than using intrinsic sexual differences, but they systems require selectable genetic markers and sex-linkage created by rare random chromosomal rearrangements. While intrinsic sexual differences should not be considered as long-term candidates for the development of robust and efficient sexing approaches, in the absence of these, the accessibility and integration of less efficient systems can provide a stop-gap measure that allows rapid start up with a minimum of investment. The International Atomic Energy Agency is funding over a 5 year period (2013-2018) a new Coordinated Research Project on "Exploring Genetic, Molecular, Mechanical and Behavioural Methods of Sex Separation in Mosquitoes" to network researchers and to address the critical need of genetic sexing strains for the implementation of the sterile insect technique (using radiation-sterilised or transgenic male mosquitoes) and for insect incompatibility technique programmes against disease-transmitting mosquitoes. Copyright © 2013 International Atomic Energy Agency. Published by Elsevier B.V. All rights reserved.

  10. Influence of free water content on the compressive mechanical behaviour of cement mortar under high strain rate

    Indian Academy of Sciences (India)

    Jikai Zhou; Xudong Chen; Longqiang Wu; Xiaowei Kan

    2011-06-01

    The effect of free water content upon the compressive mechanical behaviour of cement mortar under high loading rate was studied. The uniaxial rapid compressive loading testing of a total of 30 specimens, nominally 37 mm in diameter and 18.5 mm in height, with five different saturations (0%, 25%, 50%, 75% and 100%, respectively) were executed in this paper. The technique ‘Split Hopkinson pressure bar’ (SHPB) was used. The impact velocity was 10 m/s with the corresponding strain rate as 102/s. Water-cement ratio of 0.5 was used. The compressive behaviour of the materials was measured in terms of the maximum stress, Young’s modulus, critical strain at maximum stress and ultimate strain at failure. The data obtained from test indicates that the similarity exists in the shape of strain–stress curves of cement mortars with different water content, the upward section of the stress–strain curve shows bilinear characteristics, while the descending stage (softening state) is almost linear. The dynamic compressive strength of cement mortar increased with the decreasing of water content, the dynamic compressive strength of the saturated specimens was 23% lower than that of the totally dry specimens. With an increase in water content, the Young’s modulus first increases and then decreases, the Young’s modulus of the saturated specimens was 23% lower than that of the totally dry specimens. No significant changes occurred in the critical and ultimate strain value as the water content is changed.

  11. May 1939 „Electoral Campaign”: Mechanisms, Procedures and Electoral Behaviour

    Directory of Open Access Journals (Sweden)

    Florin Grecu

    2012-06-01

    Full Text Available The elections from 1st – 2nd of June 1939, during the authoritarian monarchy, 1938-1940, emphasised habits, methods and electoral mechanisms specific to any authoritarian regimes. The Maire was the one organising the elections, mainly because he was also making the electoral lists and in charge with the train transportation of the citizens to the voting precinct; trough the telephone network, the results of the elections were communicated to the Interior Ministry, who was to be informed at any moment about the data given by the Maire and also the voting and occasional incidents occurring during the elections. The need of control above the citizen’s vote represented the main mission of the local authorities during the day of the voting, precisely by the repression organs, The Police and the Constabulary.

  12. An experimental evaluation of the fully coupled hysteretic electro-mechanical behaviour of piezoelectric actuators

    Energy Technology Data Exchange (ETDEWEB)

    Butcher, Mark [Department of Engineering, CERN, 1211 Geneva (Switzerland); Davino, Daniele, E-mail: davino@unisannio.it [Department of Engineering, University of Sannio, Benevento (Italy); Giustiniani, Alessandro; Masi, Alessandro [Department of Engineering, CERN, 1211 Geneva (Switzerland)

    2016-04-01

    Piezoelectrics are the most commonly used of the multifunctional smart materials in industrial applications, because of their relatively low cost and ease of use in electric and electronic oriented applications. Nevertheless, while datasheets usually give just small signal quasi-static parameters, their full potential can only be exploited only if a full characterization is available because the maximum stroke or the higher piezo coupling coefficients are available at different electro-mechanical biases, where often small signal analysis is not valid. In this paper a method to get the quasi-static fully coupled characterization is presented. The method is tested on a commercial piezo actuator but can be extended to similar devices.

  13. Experimental study of the hydro-mechanical behaviour of unsaturated argillaceous rocks

    Directory of Open Access Journals (Sweden)

    Espitia Jairo Martin

    2016-01-01

    Full Text Available The aim of this paper is to study the influence of total suction on some physical/mechanical properties related to argillaceous rocks from the Colombian Andes. A wetting path was applied to the rocks using the vapor transfer technique with continuous recording of mass and deformations. Uniaxial compression tests were conducted on specimens at different levels of suction. In addition, microstructural observations are carried out using a Mercury Intrusion Porosimeter Apparatus. Results from the laboratory tests indicate that anisotropic deformations took place during the wetting path. Also, total suction contributed to a considerable and non-linear reduction in the compressional wave velocity, peak compressive stress, and elastic modulus of the tested samples. Microstructural analysis indicated the influence of the size and number of the pores in the samples on their high levels of suction.

  14. Investigation on actuation and thermo-mechanical behaviour of Shape Memory Alloy spring using hot water

    Science.gov (United States)

    Chouhan, Priya; Nath, Tameshwer; Lad, B. K.; Palani, I. A.

    2016-09-01

    In this paper, hot water is used as an actuation media for Shape memory alloy and its impact on the morphology of structure of Nitinol Shape Memory Alloy (SMA), is presented. With hot water actuation as the temperature reaches 70-80°C, spring gets fully compressed for the first few cycles followed by a displacement loss in actuation. This actuation loss is then studied with different characterization methods such as Thermo Gravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM). With SEM results, it can be inferred that the energy source is not deteriorating the structure. Results observed from TGA shows high oxygen content at lower temperature limits with hot water actuation which suggest the need of conducting experiments in inert atmosphere. As a possible mechanism, a new actuation medium is introduced and various results can be seen in the paper discussed below.

  15. Geometrical and material parameters to assess the macroscopic mechanical behaviour of fresh cranial bone samples.

    Science.gov (United States)

    Auperrin, Audrey; Delille, Rémi; Lesueur, Denis; Bruyère, Karine; Masson, Catherine; Drazétic, Pascal

    2014-03-21

    The present study aims at providing quantitative data for the personalisation of geometrical and mechanical characteristics of the adult cranial bone to be applied to head FE models. A set of 351 cranial bone samples, harvested from 21 human skulls, were submitted to three-point bending tests at 10 mm/min. For each of them, an apparent elastic modulus was calculated using the beam's theory and a density-dependant beam inertia. Thicknesses, apparent densities and percentage of ash weight were also measured. Distributions of characteristics among the different skull bones show their symmetry and their significant differences between skull areas. A data analysis was performed to analyse potential relationship between thicknesses, densities and the apparent elastic modulus. A specific regression was pointed out to estimate apparent elastic modulus from the product of thickness by apparent density. These results offer quantitative tools in view of personalising head FE models and thus improve definition of local injury criteria for this body part.

  16. submitter An experimental evaluation of the fully coupled hysteretic electro-mechanical behaviour of piezoelectric actuators

    CERN Document Server

    Butcher, Mark; Giustiniani, Alessandro; Masi, Alessandro

    2016-01-01

    Piezoelectrics are the most commonly used of the multifunctional smart materials in industrial applications, because of their relatively low cost and ease of use in electric and electronic oriented applications. Nevertheless, while datasheets usually give just small signal quasi-static parameters, their full potential can only be exploited only if a full characterization is available because the maximum stroke or the higher piezo coupling coefficients are available at different electro-mechanical biases, where often small signal analysis is not valid. In this paper a method to get the quasi-static fully coupled characterization is presented. The method is tested on a commercial piezo actuator but can be extended to similar devices.

  17. Mechanical behaviour of glass fibre reinforced composite at varying strain rates

    Science.gov (United States)

    Acharya, Saikat; Mondal, D. K.; Ghosh, K. S.; Mukhopadhyay, A. K.

    2017-03-01

    Here we report the results of compressive split Hopkinson pressure bar experiments (SHPB) conducted on unidirectional glass fibre reinforced polymer (GFRP) in the strain rate regime 5  ×  102–1.3  ×  103 s‑1. The maximum compressive strength of GFRP was found to increase by as much as 55% with increase in strain rate. However, the corresponding relative strain to failure response was measured to increase only marginally with increase in strain rates. Based on the experimental results and photomicrographs obtained from FE-SEM based post mortem examinations, the failure phenomena are suggested to be associated with increase in absorption of energy from low to high strain rates. Attempts have been made to explain these observations in terms of changes in deformation mechanisms primarily as a function of strain rates.

  18. Effect of coating mild steel with CNTs on its mechanical properties and corrosion behaviour in acidic medium

    Science.gov (United States)

    Abdulmalik Abdulrahaman, Mahmud; Kamaldeeen Abubakre, Oladiran; Ambali Abdulkareem, Saka; Oladejo Tijani, Jimoh; Aliyu, Ahmed; Afolabi, Ayo Samuel

    2017-03-01

    The study investigated the mechanical properties and corrosion behaviour of mild steel coated with carbon nanotubes at different coating conditions. Multi-walled carbon nanotubes (MWCNTs) were synthesized via the conventional chemical vapour deposition reaction using bimetallic Fe–Ni catalyst supported on kaolin, with acetylene gas as a carbon source. The HRSEM/HRTEM analysis of the purified carbon materials revealed significant reduction in the diameters of the purified MWCNT bundles from 50 nm to 2 nm and was attributed to the ultrasonication assisted dispersion with surfactant (gum arabic) employed in purification process. The network of the dispersed MWCNTs was coated onto the surfaces of mild steel samples, and as the coating temperature and holding time increased, the coating thickness reduced. The mechanical properties (tensile strength, yield strength, hardness value) of the coated steel samples increased with increase in coating temperature and holding time. Comparing the different coating conditions, coated mild steels at the temperature of 950 °C for 90 min holding time exhibited high hardness, yield strength and tensile strength values compared to others. The corrosion current and corrosion rate of the coated mild steel samples decreased with increase in holding time and coating temperature. The lowest corrosion rate was observed on sample coated at 950 °C for 90 min.

  19. The impact of the amount of polypropylene fibres on spalling behaviour and residual mechanical properties of Reactive Powder Concretes

    Directory of Open Access Journals (Sweden)

    Hager I.

    2013-09-01

    Full Text Available In this paper, an experimental study on the spalling behaviour and mechanical properties of Reactive Powder Concretes (RPCs in high temperature are presented. The research program was established to evaluate the impact of low melting temperature polypropylene fibres PP on mechanical properties evolution with temperature but also to verify the effectiveness of their addition to prevent spalling. Three sets of RPC specimens were prepared for this study with different amount of PP fibres (no fibres, 1.0 kg/m3 and 2.0 kg/m3. The addition of PP fibres reduces the initial compressive strength of the RPC material by approx. 14% no significant influence on modulus of elasticity was observed. Addition of 1 kg/m3 of PP fibres in RPC, seem not to give a sufficient protection against occurrence of spalling phenomenon. By adding 2 kg/m3 of PP fibres the risk of spalling is significantly reduced.

  20. The Role of Dietary Polyphenols on Adult Hippocampal Neurogenesis: Molecular Mechanisms and Behavioural Effects on Depression and Anxiety

    Directory of Open Access Journals (Sweden)

    Gisele Pereira Dias

    2012-01-01

    Full Text Available Although it has been long believed that new neurons were only generated during development, there is now growing evidence indicating that at least two regions in the brain are capable of continuously generating functional neurons: the subventricular zone and the dentate gyrus of the hippocampus. Adult hippocampal neurogenesis (AHN is a widely observed phenomenon verified in different adult mammalian species including humans. Factors such as environmental enrichment, voluntary exercise, and diet have been linked to increased levels of AHN. Conversely, aging, stress, anxiety and depression have been suggested to hinder it. However, the mechanisms underlying these effects are still unclear and yet to be determined. In this paper, we discuss some recent findings addressing the effects of different dietary polyphenols on hippocampal cell proliferation and differentiation, models of anxiety, and depression as well as some proposed molecular mechanisms underlying those effects with particular focus on those related to AHN. As a whole, dietary polyphenols seem to exert positive effects on anxiety and depression, possibly in part via regulation of AHN. Studies on the effects of dietary polyphenols on behaviour and AHN may play an important role in the approach to use diet as part of the therapeutic interventions for mental-health-related conditions.

  1. Behavioural evidence for separate mechanisms of audiovisual temporal binding as a function of leading sensory modality.

    Science.gov (United States)

    Cecere, Roberto; Gross, Joachim; Thut, Gregor

    2016-06-01

    The ability to integrate auditory and visual information is critical for effective perception and interaction with the environment, and is thought to be abnormal in some clinical populations. Several studies have investigated the time window over which audiovisual events are integrated, also called the temporal binding window, and revealed asymmetries depending on the order of audiovisual input (i.e. the leading sense). When judging audiovisual simultaneity, the binding window appears narrower and non-malleable for auditory-leading stimulus pairs and wider and trainable for visual-leading pairs. Here we specifically examined the level of independence of binding mechanisms when auditory-before-visual vs. visual-before-auditory input is bound. Three groups of healthy participants practiced audiovisual simultaneity detection with feedback, selectively training on auditory-leading stimulus pairs (group 1), visual-leading stimulus pairs (group 2) or both (group 3). Subsequently, we tested for learning transfer (crossover) from trained stimulus pairs to non-trained pairs with opposite audiovisual input. Our data confirmed the known asymmetry in size and trainability for auditory-visual vs. visual-auditory binding windows. More importantly, practicing one type of audiovisual integration (e.g. auditory-visual) did not affect the other type (e.g. visual-auditory), even if trainable by within-condition practice. Together, these results provide crucial evidence that audiovisual temporal binding for auditory-leading vs. visual-leading stimulus pairs are independent, possibly tapping into different circuits for audiovisual integration due to engagement of different multisensory sampling mechanisms depending on leading sense. Our results have implications for informing the study of multisensory interactions in healthy participants and clinical populations with dysfunctional multisensory integration. © 2016 The Authors. European Journal of Neuroscience published by Federation

  2. Coupling between mechanical and neural behaviour in the human first dorsal interosseous muscle.

    Science.gov (United States)

    Hudson, Anna L; Taylor, Janet L; Gandevia, Simon C; Butler, Jane E

    2009-02-15

    The neural drive to a muscle and its biomechanical properties determine the force at a joint. These factors may be centrally linked. We studied the relationship between the ability of first dorsal interosseous muscle (FDI) to generate index flexion force around the metacarpophalangeal joint and the neural drive it receives in a voluntary contraction. The role of FDI was assessed in two thumb postures, thumb 'down' (thumb abducted) and thumb 'up' (thumb extended), and at different thumb carpometacarpal angles. These postures were designed to change acutely the flexion moment arm for FDI. The flexion twitch force evoked by supramaximal stimulation of the ulnar nerve was measured in the two postures and the change in moment arm was assessed by ultrasonography. Subjects also made voluntary flexion contractions of the index finger of approximately 5 N in both postures during which neural drive to FDI and the long finger flexor muscles was measured using surface EMG. Recordings of FDI EMG were normalized to the maximal M wave. Five of the 15 subjects also had a radial nerve block to eliminate any co-contraction of the extensor muscles, and extensor muscle EMG was monitored in subjects without radial nerve block. Compared to thumb up, flexion twitch force was approximately 60% greater, and the flexion moment arm was approximately 50% greater with the thumb down. There was minimal effect of altered carpometacarpal angle on flexion twitch force for either thumb posture. During voluntary flexion contractions, normalized FDI EMG was approximately 28% greater with thumb down, compared to thumb up, with no consistent change in neural drive to the long flexors. Hence, the contribution of FDI to index finger flexion can be altered by changes in thumb position. This is linked to changes in neural drive to FDI such that neural drive increases when the mechanical contribution increases, and provides a central mechanism to produce efficient voluntary movements.

  3. Early Rupture of an Ultralow Duodenal Stump after Extended Surgery for Gastric Cancer with Duodenal Invasion Managed by Tube Duodenostomy and Cholangiostomy

    Directory of Open Access Journals (Sweden)

    Konstantinos Blouhos

    2013-01-01

    Full Text Available When dealing with gastric cancer with duodenal invasion, gastrectomy with distal resection of the duodenum is necessary to achieve negative distal margin. However, rupture of an ultralow duodenal stump necessitates advanced surgical skills and close postoperative observation. The present study reports a case of an early duodenal stump rupture after subtotal gastrectomy with resection of the whole first part of the duodenum, complete omentectomy, bursectomy, and D2+ lymphadenectomy performed for a pT3pN2pM1 (+ number 13 lymph nodes adenocarcinoma of the antrum. Duodenal stump rupture was managed successfully by end tube duodenostomy, without omental patching, and tube cholangiostomy. Close assessment of clinical, physical, and radiological signs, output volume, and enzyme concentration of the tube duodenostomy, T-tube, and closed suction drain, which was placed near the tube duodenostomy site to drain the leak around the catheter, dictated postoperative management of the external duodenal fistula.

  4. Analysis of Gastric and Duodenal Eosinophils in Children with Abdominal Pain Related Functional Gastrointestinal Disorders According to Rome III Criteria.

    Science.gov (United States)

    Lee, Eun Hye; Yang, Hye Ran; Lee, Hye Seung

    2016-07-30

    Abdominal pain-related functional gastrointestinal disorder (AP-FGID) is common in children and adults. However, the mechanism of AP-FGID is not clearly known. Recently, micro-inflammation, especially eosinophilia in the gastrointestinal tract, was suggested in the pathophysiology of AP-FGID in adults. The aim of this study was to evaluate the association of gastric and duodenal eosinophilia with pediatric AP-FGID. In total, 105 pediatric patients with AP-FGID were recruited and classified into 4 subgroups based on the Rome III criteria. Eosinophil counts in the gastric and duodenal tissues of children with AP-FGID were compared to those from normal pathology references or those of children with Helicobacter pylori infection. Tissue eosinophil counts were also compared among the 4 subtypes of AP-FGID. Eosinophil counts in the gastric antrum and body were significantly higher in children with AP-FGID than normal reference values. Duodenal eosinophil counts were higher in children with AP-FGID, but not significantly when compared with normal reference values. There were no significant differences in eosinophil counts of the stomach or duodenum among the 4 subtypes of AP-FGID. Eosinophils counts in the gastric antrum and body were significantly higher in children with H. pylori infection than in those with AP-FGID. Duodenal eosinophilia was prominent in cases of H. pylori infection, but not statistically significant when compared with AP-FGID. Our study revealed that gastric eosinophilia is associated with AP-FGID in children, regardless of the subtype of functional abdominal pain. This suggests some contribution of gastrointestinal eosinophils in the development of pediatric AP-FGID.

  5. Symptomatic duodenal perforation by inferior vena cava filter.

    Science.gov (United States)

    Baptista Sincos, Anna Pw; Sincos, Igor R; Labropoulos, Nicos; Donegá, Bruno C; Klepacz, Andrea; Aun, Ricardo

    2017-01-01

    Objectives Duodenal perforation by an inferior vena cava filter is rare and life threatening. Our objective is to find out number of occurrences and compare diagnosis and treatments. Method The reference list of Malgor's review in 2012 was considered as well as all new articles with eligible features. Search was conducted on specific databases: MEDLINE, Web of Sciences, and Literatura Latino-Americana e do Caribe em Ciências da Saúde. Results Most of the patients presented with upper abdominal pain and the use of radiologic studies was crucial for diagnosis. The most common treatment was laparotomy with filter or strut removal plus duodenum repair. However, clinical conditions of patients must be considered and the endovascular technique with endograft deployment into inferior vena cava may be an alternative. Conclusion Duodenal perforation by an inferior vena cava filter is uncommon and in high-risk surgical patients endovascular repair must be considered.

  6. Epidermal growth factor inhibits cysteamine-induced duodenal ulcers

    DEFF Research Database (Denmark)

    Poulsen, Steen Seier

    1983-01-01

    The effect of the duodenal ulcerogen cysteamine on secretion of epidermal growth factor from Brunner's gland pouches was studied in the rat. Total output of immunoreactive epidermal growth factor was reduced to approximately 55%, compared with controls, 5 h after administration of cysteamine (300...... mg/kg, s.c.). Furthermore, measurements on tissue extracts of the pouches revealed that 5 h after cysteamine treatment, Brunner's glands were depleted of epidermal growth factor. The effect on ulcer development of intraduodenally applied exogenous epidermal growth factor (1 micrograms/kg . h) also...... factor used, when tested on chronic fistula rats, had no effect on acid secretion and did not influence bicarbonate secretion from Brunner's gland pouches. These results demonstrate that epidermal growth factor has a cytoprotective effect on the duodenal mucosa, and it is suggested that inhibition...

  7. Total Robotic Biliopancreatic Diversion with Duodenal Switch Technique.

    Science.gov (United States)

    Antanavicius, Gintaras; Mohammed, Ricardo; Van Houtte, Olivier

    2016-12-31

    The use of robotic bariatric surgery has increased significantly since its advent in 1999. Its utility and safety has been demonstrated in the literature for all bariatric procedures, including most recently the biliopancreatic diversion with duodenal switch (BPDDS). The robotic-assisted biliopancreatic diversion with duodenal switch (RBPDDS) was first described by Sudan et al. in 2007 with the use of the robot primarily for the duodeno-ileal anastomosis, then in 2015, the same authors described 59 cases of totally RBPDDS using the robot for the most of the operation, but still utilizing laparoscopic staplers. Robotic staplers were introduced recently and it became possible to utilize robot throughout the entire procedure without relying on stapling performed by an assistant. Described here is the technique of a total RBPDDS utilizing robotic staplers.

  8. An Unusual Cause of Duodenal Obstruction: Persimmon Phytobezoar.

    Science.gov (United States)

    Fan, Shengxian; Wang, Jing; Li, Yousheng

    2016-12-01

    Duodenal phytobezoar, an unusual cause of acute duodenal obstruction, is rarely seen. The most common cause of this type of bezoar is persimmon. It frequently arises from underlying gastrointestinal tract pathologies (gastric surgery, etc.). Here, we report the case of a 66-year-old man who had undergone distal gastrectomy with Billroth I reconstruction for gastric cancer and experienced severe epigastric discomfort, abdominal pain, and vomiting for a few days. The abdominal computed tomography scan showed a large-sized mass in the horizontal portion of the duodenum. On following endoscopic examination, a large phytobezoar was revealed in the duodenum. He was treated with endoscopic fragmentation combined with nasogastric Coca-Cola. The patient tolerated the procedure well and resumed a normal oral diet 3 days later.

  9. Lipase assay in duodenal juice using a conductimetric method.

    Science.gov (United States)

    Ballot, C; Favre-Bonvin, G; Wallach, J M

    1984-11-15

    Lipase activity in duodenal juice is known to undergo important variations in pathologic states, especially in cases of chronic pancreatitis. Almost all of the current assay methods are based on the measurement of hydrolysis of olive oil or triolein, mainly by potentiometry. As we have developed a conductimetric method for enzyme activity measurements, we have applied it to lipase assay. A higher experimental conductimetric sensitivity is obtained when liberated acids have a short chain (higher limiting equivalent conductivity). We have therefore used triacetin as a substrate and compared out method with potentiometry (pH-stat) and spectrophotometry. The correlation coefficients of both methods with conductimetry were 0.94 and 0.97, respectively, indicating that the conductimetric method may be used for lipase assay in duodenal juice, using triacetin as a substrate.

  10. Duodenal gossypiboma: a case report and literature review.

    Science.gov (United States)

    Velasco-Mata, Stephany; Díaz-Gómez, Marialy; Cova-Bianco, Tamarys; Hopp-Mora, Evelyn; Rodriguez-Rojas, Roselin; Chirinos-Malave, Yeirama; Carreiro-Rodriguez, Manuel

    2015-09-01

    Gossypiboma is a retained surgical cotton matrix material in the body after a surgical procedure. Cases are rarely reported due to medico-legal concerns. Although infrequent, it causes serious morbidity and even mortality if left undiagnosed. We present the case of a trans-mural migration of gossypiboma and a review of the literature. Gossypiboma's trans-duodenal migration is a rare complication of retained gauzes. Cases reported in the literature were easy to diagnose based on clinical grounds and endoscopic studies.

  11. An uncommon cause of gastro-duodenal ulceration

    Institute of Scientific and Technical Information of China (English)

    Sebastian Mallach; Uwe Ramp; Andreas Erhardt; Marcus Schmitt; Dieter H(a)ussinger

    2008-01-01

    Gastrointestinal ulcers occur frequently and are mainly caused by H pylori infection.In this report, we present a rare case of gastro-duodenal ulcer following selective internal radiation therapy (SIRT).SIRT is a palliative treatment for unresectable liver tumours.During SIRT,90Y-microspheres are infused into the hepatic artery.Pretreatment evaluation for the presence of arterial shunts to neighbouring organs should be determined in order to avoid complications of SIRT.

  12. Gallstone ileus of duodenum with huge duodenal stone

    OpenAIRE

    Mohammad Ehsan; Mohammad Reza Ahangaran

    2006-01-01

    Gastrointestinal obstruction by a gallstone is an uncommon but important complication of biliary stone disease which mostly affects the elderly. The classic triad of radiological features includes pneumobilia, ectopic gallstone and evidence of intestinal obstruction. Terminal ileum is the most common site of obstruction, followed by jejunum and gastric outlet. We present a case of duodenal gallstone ileus of a large, fluid-density mixed biliary stone with a peripheral rim of hyperdensity (ver...

  13. Peptic Ulcer Disease Different Pathogenesis of Duodenal and Gastric Ulcer

    OpenAIRE

    Hendra Koncoro; I Dewa Nyoman Wibawa

    2015-01-01

    Despite decrease frequency of Helicobacter pylori (H. pylori) due to eradication therapy, peptic ulcer disease as a manifestation of this infection is still remain a health burden. Understanding the physiology of gastric acid secretion and its alteration by H. pylori induced inflammation will aid physician in differentiating peptic ulcer disease based on its location. Duodenal ulcer and gastric ulcer disease are two common condition that usually found in peptic ulcer. Recognition of symptoms ...

  14. An Unusual Cause of Gastrointestinal Bleeding: Duodenal Lipoma

    Directory of Open Access Journals (Sweden)

    R. Kadaba

    2011-04-01

    Full Text Available Common causes of chronic upper gastrointestinal bleeding include oesophageal varices, gastroduodenal ulcers and malignancy, and patients mostly present with iron deficiency type anaemia. We present the case of a 60-year-old lady who presented with iron deficiency anaemia and on investigation was found to have a large duodenal polyp requiring surgical excision. On histological examination, the polyp was revealed to be a lipoma. We review the recent literature and formulate a management plan for this rare entity.

  15. Surface analysis and mechanical behaviour mapping of vertically aligned CNT forest array through nanoindentation

    Science.gov (United States)

    Koumoulos, Elias P.; Charitidis, C. A.

    2017-02-01

    Carbon nanotube (CNT) based architectures have increased the scientific interest owning to their exceptional performance rendering them promising candidates for advanced industrial applications in the nanotechnology field. Despite individual CNTs being considered as one of the most known strong materials, much less is known about other CNT forms, such as CNT arrays, in terms of their mechanical performance (integrity). In this work, thermal chemical vapor deposition (CVD) method is employed to produce vertically aligned multiwall (VA-MW) CNT carpets. Their structural properties were studied by means of scanning electron microscopy (SEM), X-Ray diffraction (XRD) and Raman spectroscopy, while their hydrophobic behavior was investigated via contact angle measurements. The resistance to indentation deformation of VA-MWCNT carpets was investigated through nanoindentation technique. The synthesized VA-MWCNTs carpets consisted of well-aligned MWCNTs. Static contact angle measurements were performed with water and glycerol, revealing a rather super-hydrophobic behavior. The structural analysis, hydrophobic behavior and indentation response of VA-MWCNTs carpets synthesized via CVD method are clearly demonstrated. Additionally, cycle indentation load-depth curve was applied and hysteresis loops were observed in the indenter loading-unloading cycle due to the local stress distribution. Hardness (as resistance to applied load) and modulus mapping, at 200 nm of displacement for a grid of 70 μm2 is presented. Through trajection, the resistance is clearly divided in 2 regions, namely the MWCNT probing and the in-between area MWCNT - MWCNT interface.

  16. Leaching behaviour and mechanical properties of copper flotation waste in stabilized/solidified products.

    Science.gov (United States)

    Mesci, Başak; Coruh, Semra; Ergun, Osman Nuri

    2009-02-01

    This research describes the investigation of a cement-based solidification/stabilization process for the safe disposal of copper flotation waste and the effect on cement properties of the addition of copper flotation waste (CW) and clinoptilolite (C). In addition to the reference mixture, 17 different mixtures were prepared using different proportions of CW and C. Physical properties such as setting time, specific surface area and compressive strength were determined and compared to a reference mixture and Turkish standards (TS). Different mixtures with the copper flotation waste portion ranging from 2.5 to 12.5% by weight of the mixture were tested for copper leachability. The results show that as cement replacement materials especially clinoptilolite had clear effects on the mechanical properties. Substitution of 5% copper flotation waste for Portland cement gave a similar strength performance to the reference mixture. Higher copper flotation waste addition such as 12.5% replacement yielded lower strength values. As a result, copper flotation waste and clinoptilolite can be used as cementitious materials, and copper flotation waste also can be safely stabilized/solidified in a cement-based solidification/stabilization system.

  17. The mechanics of swallowing and the muscular control of diverse behaviours in gopher snakes.

    Science.gov (United States)

    Moon, B R

    2000-09-01

    Snakes are excellent subjects for studying functional versatility and potential constraints because their movements are constrained to vertebral bending and twisting. In many snakes, swallowing is a kind of inside-out locomotion. During swallowing, vertebral bends push food from the jaws along a substantial length of the body to the stomach. In gopher snakes (Pituophis melanoleucus) and king snakes (Lampropeltis getula), swallowing often begins with lateral bending of the head and neck as the jaws advance unilaterally over the prey. Axial movement then shifts to accordion-like, concertina bending as the prey enters the oesophagus. Once the prey is completely engulfed, concertina bending shifts to undulatory bending that pushes the prey to the stomach. The shift from concertina to undulatory bending reflects a shift from pulling the prey into the throat (or advancing the mouth over the prey) to pushing it along the oesophagus towards the stomach. Undulatory kinematics and muscular activity patterns are similar in swallowing and undulatory locomotion. However, the distinct mechanical demands of internal versus external force exertion result in different duty factors of muscle activity. Feeding and locomotor movements are thus integral functions of the snake axial system.

  18. Influence of clay swelling on the mechanical behaviour of Egyptian Helwan limestone

    Science.gov (United States)

    Aly, Nevin

    2016-04-01

    Clay minerals exist naturally in the majority of different Egyptian limestones types. Changes in the dimensions of clays during swelling / shrinking process induced by changes in the environmental conditions can result in acceleration the deterioration of the hosting stone. Petrographic investigation by scanning - electron microscope (SEM) of Helwan limestone (biomicritic limestone) revealed distribution of a typical smectite morphology (curled - leaf shape) beside abundance of glauconite pellets within the stone material. The clay frication extracted from Helwan reached 10% and oriented aggregates samples were analyzed by X- ray diffraction (XRD) and confirmed the identification of smectite as the main mineral in the clay frication. To study the effect of the clay content on the mechanical behavior of Helwan limestone, hygric swelling test was performed at first by using displacement sensor and then the effect of multiple wetting/ drying cycles on the stone strength was determined using unconfined compressive strength (UCS). Results revealed that there was a significant correlation between degree of swelling of the clay and strength of the limestone.

  19. Influence of processing on the microstructure and mechanical behaviour of Mo-Si-B alloys

    Energy Technology Data Exchange (ETDEWEB)

    Krueger, M [Otto von Guericke University Magdeburg, Institute for Materials and Joining Technology, PO Box 4120, D-39016 Magdeburg (Germany); Saage, H [University of Applied Sciences Landshut, Mechanical Engineering, D- 84036 Landshut (Germany); Heilmaier, M [Technical University Darmstadt, Department Materials Science, D-64287 Darmstadt (Germany); Boening, M; Kestler, H, E-mail: m.heilmaier@phm.tu-darmstadt.d [Plansee SE, Technology Center, A-6600 Reutte in Tyrol (Austria)

    2010-07-01

    Mo-Si-B materials consisting of a Mo(Si) solid solution and the intermetallic phases Mo{sub 3}Si and Mo{sub 5}SiB{sub 2} (T2) were prepared by mechanical alloying (MA) as the crucial step of a powdermetallurgical process. After consolidation via an industrial processing route (cold isostatic pressing, sintering, hot isostatic pressing) the resulting microstructures of Mo-Si-B alloys up to 45% of intermetallic phases reveal a continuous {alpha}-Mo matrix with embedded, homogeneously distributed intermetallic particles. Clearly, increasing the amount of Mo solid solution reduces the BDTT (demonstrated by three point bending tests between room temperature and 1200{sup 0}C), however, values below 900{sup 0}C could not be obtained due to grain boundary embrittlement caused by Si segregation. Alloying with Zr was proven by Auger analysis in Mo-Si solid solutions to reduce this segregation. Therefore, in a second trial Zr as a (micro-) alloying element was added. The influence of microalloying on ductility and strength is comparatively discussed with reference compositions Mo-6Si-5B and Mo-9Si-8B.

  20. The mechanism of cathodic electrodeposition of epoxy coatings and the corrosion behaviour of the electrodeposited

    Directory of Open Access Journals (Sweden)

    VESNA B. MISKOVIC-STANKOVIC

    2002-05-01

    Full Text Available The model of organic film growth on a cathode during electrodeposition process proposes the current density-time and film thickness-time relationships and enables the evaluation of the rate contants for the electrochemical reaction of OH– ion evolution and for the chemical reaction of organic film deposition. The dependences of film thickness and rate constants on the applied voltage, bath temperature and resin concentration in the electrodeposition bath have also been obtained. The deposition parameters have a great effect on the cathodic electrodeposition process and on the protective properties of the obtained electrodeposited coatings. From the time dependences of the pore resistance, coating capacitance and relative permittivity, obtained from impedance measurements, the effect of applied voltage, bath temperature and resin concentration on the protective properties of electrodeposited coatings has been shown. Using electrochemical impedance spectroscopy, thermogravimetric analysis, gravimetric liquid sorption experiments, differential scanning calorimetry and optical miscroscopy, the corrosion stability of epoxy coatings was investigated. A mechanism for the penetration of electrolyte through an organic coating has been suggested and the shape and dimensions of the conducting macropores have been determined. It was shown that conduction through a coating depends only on the conduction through the macropores, although the quantity of electrolyte in the micropores of the polymer net is about one order of magnitude greater than that inside the conducting macropores.

  1. Dynamics of micromechanisms controlling the mechanical behaviour of industrial single crystal superalloys

    Indian Academy of Sciences (India)

    M Benyoucef; A Coujou; F Pettinari-Sturmel; S Raujol; B Boubker; N Clément

    2003-02-01

    When deforming bulk material, micromechanisms involving moving defects result in mechanical characteristics observed at a macroscopic scale. In situ straining of microsamples in a Transmission Electron Microscope. provides the unique advantage of observing the dislocation dynamics involved in such microdeformation processes under the combined effects of stress and temperature. Here the efficiency of this technique is illustrated by describing the different obstacles controlling the movement of dislocations in a two-phase industrial single crystal superalloy. At 25° and 850°C, different core structures of the moving dislocations as well as several ways of crossing obstacles are described, which concern the movement of dislocations in channels, at $\\gamma /\\gamma' $ interfaces and while shearing $\\gamma' $ precipitates. From these observations, a quantitative analysis is developed leading to the evaluation of the critical propagation stresses involved in the channels of the matrix and when crossing the interfaces. This allows to discuss the various sites of resistance opposed to the dislocation movements and controlling the macroscopic deformation.

  2. Effect of chain conformation on micro-mechanical behaviour of MEH–PPV thin film

    Indian Academy of Sciences (India)

    P Wang; L L Wu; D Zhang; H Q Zhang

    2013-10-01

    The morphology, photoluminescent properties and micro-mechanical character of poly[2-methoxy-5-(2'-ethylhexyloxy)--phenylene vinylene] (MEH–PPV) thin films prepared from toluene (T film) and chloroform (C film) were studied by transmission electron microscopy (TEM), absorption, photoluminescence spectrophotometry and nanoindentation test. The morphological feature of worm-like entities which appeared in T film was ∼10–20 nm in length and 3–5 nm in width. The C film displayed the continuous cotton fibre-shaped morphology. In contrast with C film, the band-edge absorption and maximum emission for T film shifted to the longer wavelength. An analysis fromTEM photograph, absorption and photoluminescence spectra indicated that different chain conformation presented in these two kinds of films. The nanoindentation test showed that the elastic modulus and indentation hardness of T film under the same experimental parameter (load: 50–200 N, loading rate: 20 N/s and holding time: 20 s) decreased by 33.3 ± 0.3 and 8.9 ± 0.5%, respectively comparing with C film. In addition, critical bending radius of these two films based on the flexible base was also evaluated from the obtained experimental results.

  3. Spring-like leg behaviour, musculoskeletal mechanics and control in maximum and submaximum height human hopping.

    Science.gov (United States)

    Bobbert, Maarten F; Richard Casius, L J

    2011-05-27

    The purpose of this study was to understand how humans regulate their 'leg stiffness' in hopping, and to determine whether this regulation is intended to minimize energy expenditure. 'Leg stiffness' is the slope of the relationship between ground reaction force and displacement of the centre of mass (CM). Variations in leg stiffness were achieved in six subjects by having them hop at maximum and submaximum heights at a frequency of 1.7 Hz. Kinematics, ground reaction forces and electromyograms were measured. Leg stiffness decreased with hopping height, from 350 N m(-1) kg(-1) at 26 cm to 150 N m(-1) kg(-1) at 14 cm. Subjects reduced hopping height primarily by reducing the amplitude of muscle activation. Experimental results were reproduced with a model of the musculoskeletal system comprising four body segments and nine Hill-type muscles, with muscle stimulation STIM(t) as only input. Correspondence between simulated hops and experimental hops was poor when STIM(t) was optimized to minimize mechanical energy expenditure, but good when an objective function was used that penalized jerk of CM motion, suggesting that hopping subjects are not minimizing energy expenditure. Instead, we speculated, subjects are using a simple control strategy that results in smooth movements and a decrease in leg stiffness with hopping height.

  4. Effects of multiple vein microjoints on the mechanical behaviour of dragonfly wings: numerical modelling.

    Science.gov (United States)

    Rajabi, H; Ghoroubi, N; Darvizeh, A; Appel, E; Gorb, S N

    2016-03-01

    Dragonfly wings are known as biological composites with high morphological complexity. They mainly consist of a network of rigid veins and flexible membranes, and enable insects to perform various flight manoeuvres. Although several studies have been done on the aerodynamic performance of Odonata wings and the mechanisms involved in their deformations, little is known about the influence of vein joints on the passive deformability of the wings in flight. In this article, we present the first three-dimensional finite-element models of five different vein joint combinations observed in Odonata wings. The results from the analysis of the models subjected to uniform pressures on their dorsal and ventral surfaces indicate the influence of spike-associated vein joints on the dorsoventral asymmetry of wing deformation. Our study also supports the idea that a single vein joint may result in different angular deformations when it is surrounded by different joint types. The developed numerical models also enabled us to simulate the camber formation and stress distribution in the models. The computational data further provide deeper insights into the functional role of resilin patches and spikes in vein joint structures. This study might help to more realistically model the complex structure of insect wings in order to design more efficient bioinspired micro-air vehicles in future.

  5. The goose is (half) cooked: a consideration of the mechanisms and interpersonal context is needed to elucidate the effects of personal financial incentives on health behaviour.

    Science.gov (United States)

    Hagger, Martin S; Keatley, David A; Chan, Derwin C K; Chatzisarantis, Nikos L D; Dimmock, James A; Jackson, Ben; Ntoumanis, Nikos

    2014-02-01

    While we agree that personal financial incentives (PFIs) may have some utility in public health interventions to motivate people in the uptake and persistence of health behaviour, we disagree with some of the sentiments outlined by Lynagh et al. (Int J Behav Med 20:114-120, 2012). Specifically, we feel that the article gives a much stronger impression that PFIs will likely lead to long-term behaviour change once the incentive has been removed than is warranted by current research. This claim has not received strong empirical support nor is it grounded in psychological theory on the role of incentives and motivation. We also feel that the presentation of some of the tenets of self-determination theory by the authors is misleading. Based on self-determination theory, we propose that PFIs, without sufficient consideration of the mechanisms by which external incentives affect motivation and the interpersonal context in which they are presented, are unlikely to lead to persistence in health behaviour once the incentive is removed. We argue that interventions that adopt PFIs as a strategy to promote health-behaviour change should incorporate strategies in the interpersonal context to minimise the undermining effect of the incentives on intrinsic motivation. Interventions should present incentives as informational regarding individuals' competence rather than as purely contingent on behavioural engagement and emphasise self-determined reasons for pursuing the behaviour.

  6. Perforated duodenal ulcer: a rare complication of deferasirox in children.

    Science.gov (United States)

    Yadav, Sunil Kumar; Gupta, Vipul; El Kohly, Ashraf; Al Fadhli, Wasmi

    2013-01-01

    Duodenal ulcer perforation in pediatric age group is an uncommon entity; hence, it is not usually considered in the differential diagnosis of acute abdomen in these patients. It is important for the emergency physician to consider perforated peptic ulcer in the differential diagnosis of children presenting with acute abdominal pain, gastrointestinal bleeding, or shock. We report a 6½-year-old male child with thalassemia major who presented to emergency room with an acute abdomen and shock, who was subsequently found to have a perforated duodenal ulcer, probably related to use of oral chelating agent, deferasirox. Although, gastrointestinal symptoms like nausea, vomiting, and abdominal pain has been mentioned as infrequent adverse event in the scientific product information of deferasirox, in our current knowledge this is the first case report of perforated duodenal ulcer after oral deferasirox. The severity of this event justifies the reporting of this case. This patient had an atypical presentation in that there were no signs or symptoms of peptic ulcer disease before perforation and shock he was successfully managed with open surgery after initial resuscitation and stabilization of his general condition.

  7. Childhood chronic gastritis and duodenitis: Role of altered sensory neuromediators

    Science.gov (United States)

    Islek, Ali; Yilmaz, Aygen; Elpek, Gulsum Ozlem; Erin, Nuray

    2016-01-01

    AIM To investigate the roles of the neuropeptides vasoactive intestinal peptide (VIP), substance P (SP), and calcitonin gene-related peptide (CGRP) in chronic gastritis and duodenitis in children. METHODS Biopsy samples from the gastric and duodenal mucosa of 52 patients and 30 control subjects were obtained. Samples were taken for pathological examination, immunohistochemical staining, enzyme activity measurements and quantitative measurements of tissue peptide levels. RESULTS We observed differential effects of the disease on peptide levels, which were somewhat different from previously reported changes in chronic gastritis in adults. Specifically, SP was increased and CGRP and VIP were decreased in patients with gastritis. The changes were more prominent at sites where gastritis was severe, but significant changes were also observed in neighboring areas where gastritis was less severe. Furthermore, the degree of changes was correlated with the pathological grade of the disease. The expression of CD10, the enzyme primarily involved in SP hydrolysis, was also decreased in patients with duodenitis. CONCLUSION Based on these findings, we propose that decreased levels of VIP and CGRP and increased levels of SP contribute to pathological changes in gastric mucosa. Hence, new treatments targeting these molecules may have therapeutic and preventive effects. PMID:27729741

  8. War, traffic and iatrogenic injuries of D3 duodenal segment

    Directory of Open Access Journals (Sweden)

    Ignjatović Dragan

    2005-01-01

    Full Text Available Background. Injuries of the duodenum at the level of aortomesenteric clamp (segment D3 are with a high incidence of death due to the development of fistula and peritonitis. In three successfully managed cases, we applied the biliary surgery method. Case reports. All three cases were with the injuries of D3 duodenal segment. The first patient suffered from the blast perforation of duodenum at the level of the aortomesenteric clamp which occurred at the 7th day after the injury. The second patient suffered from the duodenal injury caused in a traffic accident. The third patient suffered from an iatrogenic injury at the beginning of D3 duodenal segment inflicted during ureterolithotomy. The described surgical procedure included basically the suture to narrow the site of the injury, then lateroterminal anastomosis with the Roux-en-Y jejunal flexure and, finally, the placement of a silicone prosthesis starting from the duodenum through the site of injury and the Roux-en-Y out. Octreotide and the total parenteral nutrition were administered to the patients postoperatively. Conclusion. The use of the releasing silicone prosthesis in all three patients provided the repair of the site of the injury with anastomosed Reux-en-Y jejunum.

  9. Childhood chronic gastritis and duodenitis: Role of altered sensory neuromediators.

    Science.gov (United States)

    Islek, Ali; Yilmaz, Aygen; Elpek, Gulsum Ozlem; Erin, Nuray

    2016-10-07

    To investigate the roles of the neuropeptides vasoactive intestinal peptide (VIP), substance P (SP), and calcitonin gene-related peptide (CGRP) in chronic gastritis and duodenitis in children. Biopsy samples from the gastric and duodenal mucosa of 52 patients and 30 control subjects were obtained. Samples were taken for pathological examination, immunohistochemical staining, enzyme activity measurements and quantitative measurements of tissue peptide levels. We observed differential effects of the disease on peptide levels, which were somewhat different from previously reported changes in chronic gastritis in adults. Specifically, SP was increased and CGRP and VIP were decreased in patients with gastritis. The changes were more prominent at sites where gastritis was severe, but significant changes were also observed in neighboring areas where gastritis was less severe. Furthermore, the degree of changes was correlated with the pathological grade of the disease. The expression of CD10, the enzyme primarily involved in SP hydrolysis, was also decreased in patients with duodenitis. Based on these findings, we propose that decreased levels of VIP and CGRP and increased levels of SP contribute to pathological changes in gastric mucosa. Hence, new treatments targeting these molecules may have therapeutic and preventive effects.

  10. Treatment of duodenal ulcer with pirenzepine and cimetidine.

    Science.gov (United States)

    Brunner, H; Dittrich, H; Kratochvil, P; Brandstätter, G; Hentschel, E; Schütze, K; Tragl, K H; Kern, H; Löffelmann, K; Zeiler, H

    1984-01-01

    The purpose of this single blind controlled multicentre trial was to compare the relative effectiveness of pirenzepine and cimetidine in healing endoscopically proven duodenal ulcers. One hundred and twenty six patients with duodenal ulcer were treated with a daily dose of 100 mg pirenzepine (50 mg each before breakfast and before the evening meal), and 128 patients were treated with 1000 mg cimetidine (200 mg with breakfast, lunch, and evening meal and 400 mg at bedtime). Endoscopy was repeated after four weeks by an endoscopist who had not been informed about the treatment. Pirenzepine showed a healing rate of 64.3%, cimetidine one of 73.4%. This difference is not statistically significant (one-sided test: chi 1(2) = 2.48). After four weeks a higher proportion of first ulcers than of recurrent lesions was healed. Pain relief was rapidly achieved with both drugs. A significant trend in favour of cimetidine may, however, not be clinically relevant considering the small difference in the absolute numbers of pain free days and nights. Adverse effects were rare and reversible. We conclude that the efficacy of pirenzepine is similar to that of cimetidine in healing duodenal ulcers. PMID:6363220

  11. Perforated duodenal ulcer: An unusual manifestation of allergic eosinophilic gastroenteritis.

    Science.gov (United States)

    Riggle, Kevin M; Wahbeh, Ghassan; Williams, Elizabeth M; Riehle, Kimberly J

    2015-11-28

    Spontaneous perforation of a duodenal ulcer secondary to allergic eosinophilic gastroenteritis (EGE) has not been previously reported. We present such a case in a teenager who presented with peritonitis. After exploration and operative repair of his ulcer, he continued to experience intermittent abdominal pain, and further evaluation revealed eosinophilic gastroenteritis in the setting of multiple food allergies. His EGE resolved after adhering to a restrictive diet. Both duodenal ulcers and EGE are very rarely seen in pediatric patients. EGE has a variable presentation depending on the layer(s) of bowel wall affected and the segment of the gastrointestinal tract that is involved. Once diagnosed, it may respond to dietary changes in patients with recognized food allergies, or to steroids in patients in whom an underlying cause is not identified. Our case highlights the need to keep EGE in the differential diagnosis when treating pediatric patients with duodenal ulcers. The epidemiology, pathophysiology, and treatment of EGE are also discussed, along with a review of the current literature.

  12. Superoxide dismutase phenotypes in duodenal ulcers: A genetic marker?

    Directory of Open Access Journals (Sweden)

    Sulekha S

    2006-01-01

    Full Text Available Background:Cu-Zn superoxide dismutases are antioxidative defensive enzymes that catalyze the reduction of superoxide anions to hydrogen peroxide. Aim:The study focuses on the association of electromorph of superoxide dismutase with duodenal ulcers, which result due to an imbalance between aggressive and defensive factors. Materials and Methods:Endoscopically confirmed 210 duodenal ulcer patients and 185 healthy individuals for comparative analysis were considered for the present study. Phenotyping of superoxide dismutase was carried out by subjecting the RBC membranes to polyacrylamide gel electrophoresis, using appropriate staining protocols. Results:Statistical analysis of SOD phenotypes revealed a significant increase of SOD AFNx012 allele and Superoxide dismutases (SOD 2-2 phenotype in duodenal ulcer group. Among these individuals, a predominance of Helicobacter pylori infection was observed. The increased preponderance of homozygotes can be explained on the basis of reduced and altered enzyme activity, which may lead to disturbance in homeostasis of antioxidant/oxidant culminating in high lipid peroxidative gastric mucosal tissue damage and ulceration. No variation in the distribution of SOD phenotypes with respect to Helicobacter pylori indicates the role of Mn-SOD rather than Cu-Zn SOD in the Helicobacter pylori infected cases as reported earlier. Conclusions:Superoxide dismutase as a genetic marker / gene modifier, encoding for an antioxidant enzyme in maintaining tissue homeostasis of the gastric mucosa is discussed.

  13. Situs inversus totalis with perforated duodenal ulcer: a case report

    Directory of Open Access Journals (Sweden)

    Khan Faiz

    2011-07-01

    Full Text Available Abstract Introduction Situs inversus is an uncommon anomaly. Situs inversus viscerum can be either total or partial. Total situs inversus, also termed as mirror image dextrocardia, is characterized by a heart on the right side of the midline while the liver and the gall bladder are on the left side. Patients are usually asymptomatic and have a normal lifespan. The exact etiology is unknown but an autosomal recessive mode of inheritance has been speculated. The first case of perforated duodenal ulcer with situs inversus was reported in 1986; here, we report the second case of this nature in the medical literature. Case presentation A 22-year-old Pakistani man presented with severe epigastric and left hypochondrial pain. Examination and investigations (chest X-ray and ultrasonography confirm peritonitis in a case of situs inversus totalis. On exploratory laparotomy, a diagnosis of situs inversus totalis with perforated duodenal ulcer was confirmed. Graham's patch closure of the duodenal ulcer was performed with absorbable sutures, and a thorough peritoneal lavage was also performed; an incidental appendectomy was also performed to avoid further diagnostic problems. Our patient had an uneventful recovery. Conclusions A diagnostic dilemma arises whenever abdominal pathology occurs in patients with situs inversus. Although an uncommon anomaly, to choose a proper surgical incision site for abdominal exploration pre-operative recognition of the condition is important.

  14. Perforated duodenal ulcer: A rare complication of deferasirox in children

    Science.gov (United States)

    Yadav, Sunil Kumar; Gupta, Vipul; El Kohly, Ashraf; Al Fadhli, Wasmi

    2013-01-01

    Duodenal ulcer perforation in pediatric age group is an uncommon entity; hence, it is not usually considered in the differential diagnosis of acute abdomen in these patients. It is important for the emergency physician to consider perforated peptic ulcer in the differential diagnosis of children presenting with acute abdominal pain, gastrointestinal bleeding, or shock. We report a 6½-year-old male child with thalassemia major who presented to emergency room with an acute abdomen and shock, who was subsequently found to have a perforated duodenal ulcer, probably related to use of oral chelating agent, deferasirox. Although, gastrointestinal symptoms like nausea, vomiting, and abdominal pain has been mentioned as infrequent adverse event in the scientific product information of deferasirox, in our current knowledge this is the first case report of perforated duodenal ulcer after oral deferasirox. The severity of this event justifies the reporting of this case. This patient had an atypical presentation in that there were no signs or symptoms of peptic ulcer disease before perforation and shock he was successfully managed with open surgery after initial resuscitation and stabilization of his general condition. PMID:23833377

  15. Perforated duodenal ulcer: A rare complication of deferasirox in children

    Directory of Open Access Journals (Sweden)

    Sunil Kumar Yadav

    2013-01-01

    Full Text Available Duodenal ulcer perforation in pediatric age group is an uncommon entity; hence, it is not usually considered in the differential diagnosis of acute abdomen in these patients. It is important for the emergency physician to consider perforated peptic ulcer in the differential diagnosis of children presenting with acute abdominal pain, gastrointestinal bleeding, or shock. We report a 6½-year-old male child with thalassemia major who presented to emergency room with an acute abdomen and shock, who was subsequently found to have a perforated duodenal ulcer, probably related to use of oral chelating agent, deferasirox. Although, gastrointestinal symptoms like nausea, vomiting, and abdominal pain has been mentioned as infrequent adverse event in the scientific product information of deferasirox, in our current knowledge this is the first case report of perforated duodenal ulcer after oral deferasirox. The severity of this event justifies the reporting of this case. This patient had an atypical presentation in that there were no signs or symptoms of peptic ulcer disease before perforation and shock he was successfully managed with open surgery after initial resuscitation and stabilization of his general condition.

  16. The effects of strain amplitude and localization on viscoelastic mechanical behaviour of human abdominal fascia.

    Science.gov (United States)

    Kirilova-Doneva, Miglena; Pashkouleva, Dessislava; Kavardzhikov, Vasil

    2016-01-01

    The purpose of the paper is to examine and compare the viscoelastic mechanical properties of human transversalis and umbilical fasciae according to chosen strain levels. A sequence of relaxation tests of finite deformation ranging from 4 to 6% strain with increment 0.3% was performed at strain rate 1.26 mm/s. Initial and equilibrium stresses T0, Teq, initial modulus E and equilibrium modulus Eeq, reduction of the stress during relaxation process ΔT, as well as the ratio (1 - Eeq /E) were calculated. The range in which parameters change their values are (0.184-1.74 MPa) for initial stress, (0.098-0.95 MPa) for equilibrium stress, (43.5-4.6 MPa) for initial modulus E. For Eeq this interval is (23.75-2.45 MPa). There are no statistically significant differences between the values of these parameters according to localization. The differences in viscoelastic properties of both fasciae are demonstrated by reduction of the stress during relaxation process and ratio (1 - Eeq /E). The values of ΔT and (1 - Eeq /E) ratio for umbilical fascia are significantly greater than that of fascia transversalis. An increase of 2% in strain leads to change of the normalized relaxation ratio of fasciae between 28%-66%. There is a weak contribution of viscous elements in fascia transversalis samples during relaxation, while in umbilical fascia the contribution of viscous component increases with strain level to 0.66 at 5.3% strain. This study adds new data for the material properties of human abdominal fascia. The results demonstrate that in chosen range of strain there is an influence of localization on visco-elastic tissue properties.

  17. Modelling the mechanical behaviour of heterogeneous Ta/TA6V welded joints: behaviour and failure criteria; Modelisation du comportement mecanique des liaisons soudees heterogenes Ta/TA6V: comportement et critere de rupture

    Energy Technology Data Exchange (ETDEWEB)

    Paris, Th

    2008-12-15

    As laser welding of two different materials (heterogeneous welding) leads to a joint having a characteristic size close to the millimetre, i.e. much smaller than that of a structure, and as such a junction displays completely different mechanical properties because of the metallurgical transformations induced by intense thermal loading, the aim of this research thesis is to develop a behaviour model, flexible and robust enough, to represent all together the mechanical behaviours of the Ta, the TA6V and the melted zone. This model must be able to take plasticity and visco-plasticity into account, and also to provide a failure criterion through damage mechanics and its coupling with the behaviour. The author first reports the experimental characterization of the base materials (Ta and TA6V) by using tensile tests under different strain rates and different directions, relaxation tests and fatigue shear tests. He also characterizes the melted zone by describing the influence of a thermal treatment (induced by welding) on the formation of the melted zone, and by using different tests: four point bending on notched specimens, nano-indentation test, and longitudinal tensile test. In a second part, the author develops the model within the framework of continuum thermodynamics, and explores the numerical issues. The last part deals with the validation of the model for the concerned materials (Ta and TA6V) and melted zone.

  18. Anisotropic mechanical behaviour of sedimentary basins inferred by advanced radar interferometry above gas storage fields

    Science.gov (United States)

    Teatini, P.; Gambolati, G.; Ferretti, A.

    2010-12-01

    Natural gas is commonly stored underground in depleted oil and gas fields to provide safe storage capacity and deliverability to market areas where production is limited, or to take advantage of seasonal price swings. In response to summer gas injection and winter gas withdrawal the reservoir expands and contracts with the overlying land that moves accordingly. Depending on the field burial depth, a few kilometres of the upper lithosphere are subject to local three-dimensional deformations with the related cyclic motion of the ground surface being both vertical and horizontal. Advanced Persistent Scatterer Interferometry (PSI) data, obtained by combining ascending and descending RADARSAT-1 images acquired from 2003 to 2008 above gas storage fields located in the sedimentary basin of the Po river plain, Italy, provide reliable measurement of these seasonal vertical ups and downs as well as horizontal displacements to and from the injection/withdrawal wells. Combination of the land surface movements together with an accurate reconstruction of the subsurface geology made available by three-dimensional seismic surveys and long-time records of fluid pore pressure within the 1000-1500 m deep reservoirs has allowed for the development of an accurate 3D poro-mechanical finite-element model of the gas injection/removal occurrence. Model calibration based on the observed cyclic motions, which are on the range of 10-15 mm and 5-10 mm in the vertical and horizontal west-east directions, respectively, helps characterize the nonlinear hysteretic geomechanical properties of the basin. First, using a basin-scale relationship between the oedometric rock compressibility cM in virgin loading conditions versus the effective intergranular stress derived from previous experimental studies, the modeling results show that the ratio s between loading and unloading-reloading cM is about 4, consistent with in-situ expansions measured by the radioactive marker technique in similar reservoirs

  19. Ambient CO2, fish behaviour and altered GABAergic neurotransmission: exploring the mechanism of CO2-altered behaviour by taking a hypercapnia dweller down to low CO2 levels.

    Science.gov (United States)

    Regan, Matthew D; Turko, Andy J; Heras, Joseph; Andersen, Mads Kuhlmann; Lefevre, Sjannie; Wang, Tobias; Bayley, Mark; Brauner, Colin J; Huong, Do Thi Thanh; Phuong, Nguyen Thanh; Nilsson, Göran E

    2016-01-01

    Recent studies suggest that projected rises of aquatic CO2 levels cause acid-base regulatory responses in fishes that lead to altered GABAergic neurotransmission and disrupted behaviour, threatening fitness and population survival. It is thought that changes in Cl(-) and HCO3 (-) gradients across neural membranes interfere with the function of GABA-gated anion channels (GABAA receptors). So far, such alterations have been revealed experimentally by exposing species living in low-CO2 environments, like many oceanic habitats, to high levels of CO2 (hypercapnia). To examine the generality of this phenomenon, we set out to study the opposite situation, hypothesizing that fishes living in typically hypercapnic environments also display behavioural alterations if exposed to low CO2 levels. This would indicate that ion regulation in the fish brain is fine-tuned to the prevailing CO2 conditions. We quantified pH regulatory variables and behavioural responses of Pangasianodon hypophthalmus, a fish native to the hypercapnic Mekong River, acclimated to high-CO2 (3.1 kPa) or low-CO2 (0.04 kPa) water. We found that brain and blood pH was actively regulated and that the low-CO2 fish displayed significantly higher activity levels, which were reduced after treatment with gabazine, a GABAA receptor blocker. This indicates an involvement of the GABAA receptor and altered Cl(-) and HCO3 (-) ion gradients. Indeed, Goldman calculations suggest that low levels of environmental CO2 may cause significant changes in neural ion gradients in P. hypophthalmus. Taken together, the results suggest that brain ion regulation in fishes is fine-tuned to the prevailing ambient CO2 conditions and is prone to disruption if these conditions change.

  20. Association of Duodenal Atresia, Malrotation, and Atrial Septal Defect in a Down-Syndrome Patient

    Directory of Open Access Journals (Sweden)

    R Angotti

    2016-04-01

    Full Text Available Duodenal atresia is the frequent cause of neonatal intestinal obstruction. The association between duodenal atresia, intestinal malrotation, cardiac anomalies and Down syndrome is infrequently reported. We present a prenatally suspected case of duodenal atresia which was associated with malrotation and atrial septal defect in a patient of Down syndrome. Duodenotomy and resection of web was performed in addition to Ladd’s procedure. Postoperative course remained uneventful.

  1. Ectopic Opening of the Common Bile Duct into the Duodenal Bulb: A Case Report

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Seong Su; Park, Soo Youn [Catholic University St. Vincent' s Hospital, Suwon (Korea, Republic of)

    2009-08-15

    An ectopic opening of the common bile duct into the duodenal bulb is a very rare congenital malformation of the bile duct, which may cause a recurrent duodenal ulcer or biliary diseases including choledocholithiasis or cholangitis. ERCP plays major role in the diagnosis of this biliary malformation. We report a case of an ectopic opening of the common bile duct into the duodenal bulb, which was detected on the upper gastrointestinal series.

  2. Management of biliary and duodenal complications of chronic pancreatitis.

    Science.gov (United States)

    Vijungco, Joseph D; Prinz, Richard A

    2003-11-01

    Biliary stricture and duodenal obstruction have been increasingly recognized as complications of chronic pancreatitis. The anatomical relationship of the distal common bile duct and the duodenum with the head of the pancreas is the main factor for their involvement in chronic pancreatitis. In hospitalized patients with pancreatitis, the incidence of biliary stricture and duodenal obstruction is reported to be about 6% and 1.2%, respectively. For patients requiring an operation for chronic pancreatitis the incidence increases to 35% for biliary stricture and 12% for duodenal obstruction. Fibrosis around the distal common bile duct can cause stenosis with obstruction of bile flow. Clinically, the presentation of these patients ranges from being asymptomatic with elevated alkaline phosphatase or bilirubin, or both, to being septic with cholangitis. Jaundice, cholangitis, hyperbilirubinemia, and persistent elevation of serum alkaline phosphatase occur more frequently in patients with pancreatitis with a biliary stricture. A twofold elevation of alkaline phosphatase is a marker of possible common duct stenosis in patients with chronic pancreatitis. The incidence of both biliary cirrhosis and cholangitis in these patients is about 10%. ERCP reveals a characteristic long, smoothly tapered stricture of the intrapancreatic common bile duct. In duodenal obstruction, the factors that convert self-limiting edema to chronic fibrosis and stricture formation are unknown, but ischemia superimposed on inflammation may be the major cause. These patients present with a prolonged history of nausea and vomiting. Barium studies typically show a long constricting lesion of the duodenum, and endoscopy reveals reactive inflammatory changes in a narrowed duodenum. Operation is indicated in patients with common bile duct strictures secondary to chronic pancreatitis when there is evidence of cholangitis, biliary cirrhosis, common duct stones, progression of stricture, elevation of alkaline

  3. A CLINICAL STUDY ON PATIENTS WITH DUODENAL ULCER PERFORATION

    Directory of Open Access Journals (Sweden)

    Kishore Babu

    2016-03-01

    Full Text Available INTRODUCTION Perforated duodenal ulcer, the most catastrophic complication was Associated with high mortality in the past due to late presentation of the patients, delay in surgery and lack of antibiotics. Various authors state that the incidence of peptic ulcer disease and perforation has been declining for the past 3 decades. Because of advances in the medical therapy of peptic ulcer with a wide range of drugs the management of peptic ulcer disease has been changing and the role of surgery has been declining. Perforation is usually seen in 3rd and 4th decades with a male preponderance and the epidemiological trend is not the same worldwide. Incidence is slightly declining in western countries. The present study has been done during the period between 2013 and 2014 in S. V. R. R. Government general hospital Tirupati. AIMS AND OBJECTIVES The aim of the present study is to analyze the probable factors for increase in incidence of duodenal ulcer perforation, with particular emphasis on assessment of impact of H2 receptor antagonists and Proton Pump inhibitors on the incidence of perforation. STUDY SETTING S. V. Medical College, Department of General Surgery, Tirupati. STUDY PERIOD Patients attending S. V. Medical College, Department of General Surgery with perforation during the period from November 2013 to October 2014. INCLUSION CRITERIA Patients between age group of more than 14 years presenting with pain abdomen and who are diagnosed to have peritonitis due to duodenal ulcer perforation. EXCLUSION CRITERIA Patients with peritonitis due causes other than duodenal ulcer. STUDY METHOD Prospective Observational study among the selected patients. Total numbers of peptic ulcer cases that were admitted in this hospital and treated either medically or surgically were noted. The details of their clinical history and findings, investigation reports, operative findings, post-operative complications were recorded. Simple closure was performed for all the

  4. Clinical diagnosis and surgical treatment of pancreatic and/or duodenal injuries

    Institute of Scientific and Technical Information of China (English)

    Zekuan Xu; Leyao Lian; Yi Miao; Xunliang Liu

    2005-01-01

    Objective: To investigate the points of the clinical diagnosis and surgical treatment for pancreatic and/or duodenal injuries. Methods: Clinical data of 30 patients who suffered from pancreatic and/or duodenal injuries were reviewed. Results: There were 29 cases who received surgical management. Of the 30 cases, 22 cases were cured, seven cases died, and postoperative complications occurred in 16 cases. The cure rate was 73.3%. Conclusion: Pancreatic and/or duodenal injuries are severe abdominal injuries and difficult to treat. The mortality and complication rate are high. The keys to successful treatments for pancreatic and/or duodenal injuries are early diagnosis, careful exploration and proper operational management.

  5. Inhibition of misleading heuristics as a core mechanism for typical cognitive development: evidence from behavioural and brain-imaging studies.

    Science.gov (United States)

    Borst, Grégoire; Aïte, Ania; Houdé, Olivier

    2015-04-01

    Cognitive development is generally conceived as incremental with knowledge of increasing complexity acquired throughout childhood and adolescence. However, several studies have now demonstrated not only that infants possess complex cognitive abilities but also that older children, adolescents, and adults tend to make systematic errors even in simple logical reasoning tasks. Therefore, one of the main issues for any theory of typical cognitive development is to provide an explanation of why at some age and in some contexts children, adolescents, and adults do not express a knowledge or cognitive principle that they already acquired when they were younger. In this review, we present convergent behavioural and neurocognitive evidence that cognitive development is more similar to a non-linear dynamic system than to a linear, stage-like system. In this theoretical framework, errors can emerge in problems similar to the ones infants or young children were succeeding when older children, adolescents, and adults rely on a misleading heuristic rather than on the correct logical algorithm to solve such problems. And the core mechanism for overcoming these errors is inhibitory control (i.e. the ability to inhibit the misleading heuristics). Therefore, typical cognitive development relies not only on the ability to acquire knowledge of incremental complexity but also to inhibit previously acquired knowledge.

  6. Complex associative memory processing and sleep: a systematic review and meta-analysis of behavioural evidence and underlying EEG mechanisms.

    Science.gov (United States)

    Chatburn, Alex; Lushington, Kurt; Kohler, Mark J

    2014-11-01

    The beneficial influence of sleep on memory consolidation is well established; however, the mechanisms by which sleep can dynamically consolidate new memories into existing networks for the continued environmental adaptation of the individual are unclear. The role of sleep in complex associative memory is an emerging field and the literature has not yet been systematically reviewed. Here, we systematically review the published literature on the role of sleep in complex associative memory processing to determine (i) if there is reasonable published evidence to support an active role for sleep facilitating complex associative processes such rule and gist extraction and false memory; (ii) to determine which sleep physiological events and states impact these processes, and to quantify the strength of these relationships through meta-analysis. Twenty-seven studies in healthy adults were identified which combined indicate a moderate effect of sleep in facilitating associative memory as tested behaviourally. Studies which have measured sleep physiology have reported mixed findings. Significant associations between sleep electrophysiology and outcome appear to be based largely on mode of acquisition. We interpret these findings as supporting reactivation based models of associative processing.

  7. Effect of post weld heat treatment on the mechanical and corrosion behaviour of welded Al-Fe-Si alloy joints

    Directory of Open Access Journals (Sweden)

    Isiaka Oluwole OLADELE

    2017-06-01

    Full Text Available Al-Fe-Si alloy was joined by shielded metal arc welding (SMAW process and the effects of post weld heat treatment (PWHT on the mechanical (tensile and hardness properties, corrosion behaviour and microstructure of the welded joints were investigated. The welded samples were divided into as-weld (AW, PWHT, base metal (BM and heat treated base metal (HT BM samples. Artificial aging was carried out on part of the welded sample at 177 °C with holding time of 8 hours to obtain the PWHT samples. The various samples were subjected to tensile, hardness and corrosion tests while microstructures of the fractured surfaces were viewed under optical microscope. From the results, it was observed that corrosion susceptibility of the alloy in 3.5 wt% NaCl solution was highly reduced after PWHT. The hardness was reduced after PWHT while the yield strength and joint efficiency was improved compared to the AW sample. The improvement in corrosion resistance, yield strength and joint efficiency are 78, 8.4 and 8.7 %, respectively.

  8. Analytical solutions of the mechanical behaviour of rock with applications to a repository for spent nuclear fuel

    Energy Technology Data Exchange (ETDEWEB)

    Jussila, P.

    1997-10-01

    Mechanical behaviour of rock is one of the main research areas of disposal of spent nuclear fuel. Various calculation programs designed to solve the problem are utilized by the planners of spent fuel disposal. The results of the numerical approaches can be validated by comparing them to the analytical solution of a simplified problem. As a basis for this study, we used Kirsch`s equations, which give the planar solution to the stress field developing around a horizontal tunnel of a circular cross section. Kirsch`s equations and the corresponding deformation (strain) and displacement fields were derived for a tunnel with and without a circular support. The rock mass was assumed to be a continuous, homogeneous and isotropic medium obeying Hooke`s law, and the time-dependent aspects of the fields were taken into account by applying the Poynting-Thomson model to the interaction between rock and a support. The Matlab code was used to calculate and visualize the results. As a result of this study, we state that the tangential, tensile stresses at the sides of the tunnel are of the same order of magnitude as the tensile strength of rock, which influences the fracturing. With a support, the effects can be moderately reduced. 7 refs.

  9. On the Genetics of Avian Personalities: mechanism and structure of behavioural strategies in the great tit (Parus major)

    NARCIS (Netherlands)

    Oers, C.H.J. van

    2003-01-01

    The need for evolutionary studies on quantitative traits that integrate genetics, development and fitness consequences is increasing. Due to the complexity, coherence and variability of behavioural traits, evolutionary biologists are therefore more and more attracted to the study of behaviour. The

  10. On the Genetics of Avian Personalities: mechanism and structure of behavioural strategies in the great tit (Parus major)

    NARCIS (Netherlands)

    Oers, C.H.J. van

    2003-01-01

    The need for evolutionary studies on quantitative traits that integrate genetics, development and fitness consequences is increasing. Due to the complexity, coherence and variability of behavioural traits, evolutionary biologists are therefore more and more attracted to the study of behaviour. The u

  11. Mechanisms of health: Education and health-related behaviours partially mediate the relationship between conscientiousness and self-reported physical health.

    Science.gov (United States)

    Lodi-Smith, Jennifer; Jackson, Joshua; Bogg, Tim; Walton, Kate; Wood, Dustin; Harms, Peter; Roberts, Brent W

    2010-03-01

    The personality trait of conscientiousness is an important predictor of health and longevity. The present research examined how conscientiousness, in combination with educational attainment and health-related behaviours, predicted self-reported physical health across adulthood. These relations were investigated in two studies, one using a large, representative sample of Illinois residents (N = 617) and the other using a community sample with a multi-method assessment of conscientiousness (N = 274). Across both studies, structural path analyses provided evidence for a model wherein conscientiousness predicted health, in part, through its relationship to both educational attainment and health-related behaviours. The findings suggest conscientiousness predicts health through a diverse set of mechanisms including, but not limited to, educational attainment and health-related behaviours.

  12. Microstructure-mechanical behaviour relationship in alumina-calcium exaluminate composites; Relaciones microestructura-comportamiento mecanico en materiales de alumina-hexaluminato calcico

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Herencia, A. J.; Moreno, R.; Baudin, C.

    2001-07-01

    The grain growth behaviour of dense alumina materials has been modified by the addition of calcium hexaluminate particles. Maximum dispersion has been obtained by colloidal processing routes. The influence of sintering temperature (1500-1600 degree centigree) on the size and shape of the alumina grains has been established. The mechanical behaviour of three composite materials with the same composition ({approx}10 vol% CA{sub 6}) and large microstructural differences has been studied in comparison with that of monophasic alumina of the same grain size. The influence of grain size and shape on toughness has been established. R-curve behaviour has been detected during fracture of the material with the alumina grains presenting the largest shape factor. (Author) 18 refs.

  13. Mechanical behaviour of Astm A 297 grade Hp joints welded using different processes; Comportamento mecanico de juntas de aco ASTM A297 grau HP soldadas por diferentes processos

    Energy Technology Data Exchange (ETDEWEB)

    Emygdio, Paulo Roberto Oliveira; Zeemann, Annelise [Tecmetal Consultoria S/C Ltda (Brazil); Almeida, Luiz Henrique de [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia

    1996-12-31

    The influence of different arc welding processes on mechanical behaviour was studied for cast heat resistant stainless steel welded joints, in the as welded conditions. ASTM A 297 grade HP with niobium and niobium/titanium additions were welded following three different welding procedures, using shielded metal arc welding gas tungsten arc welding and plasma arc welding, in six welded joints. The welded joint mechanical behaviour was evaluated by ambient temperature and 870 deg C tensile tests; and creep tests at 900 deg C and 50 MPa. Mechanical test results showed that the welding procedure qualification following welding codes is not suitable for high temperature service applications. (author) 7 refs., 2 figs., 8 tabs.

  14. Wave behaviour and noncomplementary particle behaviour in the same experiment

    Energy Technology Data Exchange (ETDEWEB)

    Rangwala, Sadiq (Tata Institute of Fundamental Research, Bombay 400 005 (India)); Roy, S.M. (Tata Institute of Fundamental Research, Bombay 400 005 (India))

    1994-07-11

    Grangier, Roger and Aspect have recently performed beautiful experiments, which show that the same single photon source shows wave behaviour or particle behaviour depending on the experimental arrangement. We propose experiments in which quantum mechanics predicts wave behaviour and noncomplementary particle behaviour in the same experiment. ((orig.))

  15. Wave behaviour and noncomplementary particle behaviour in the same experiment

    Science.gov (United States)

    Rangwala, Sadiq; Roy, S. M.

    1994-07-01

    Grangier, Roger and Aspect have recently performed beautiful experiments, which show that the same single photon source shows wave behaviour or particle behaviour depending on the experimental arrangement. We propose experiments in which quantum mechanics predicts wave behaviour and noncomplementary particle behaviour in the same experiment.

  16. Stereomicroscopic and ultrastructural characterization of propionitrile-induced duodenal ulcer in the rat

    DEFF Research Database (Denmark)

    Poulsen, Steen Seier

    1978-01-01

    Acute duodenal ulcer produced by subcutaneous injection of propionitrile in rats was studied by stereo, light, and electron microscopy in order to gain insight into the localization and mechanism of initial cell injury. Stereomicroscopy revealed an initial fissuring and splitting of the tips...... of the villus folds within 4 hours after two injections of propionitrile. This was followed by sloughing of the epithelium, shortening and effacement of the villus folds, and within 24 hours the appearance of discrete ulcers in the mucosa of the proximal duodenum. In most of the rats, two ulcers developed......: the first and larger ulcer was on the antimesenteric side of the duodenum, and the other, a small and more superficial one, was on the opposite wall. Ultrastructural lesions appeared in the absorptive epithelial cells of the proximal duodenum within 5 hours following a single dose of propionitrile...

  17. Mechanistic comparison between gastric bypass vs. duodenal switch with sleeve gastrectomy in rat models.

    Directory of Open Access Journals (Sweden)

    Yosuke Kodama

    Full Text Available BACKGROUND: Both gastric bypass (GB and duodenal switch with sleeve gastrectomy (DS have been widely used as bariatric surgeries, and DS appears to be superior to GB. The aim of this study was to better understand the mechanisms leading to body weight loss by comparing these two procedures in experimental models of rats. METHODS: Animals were subjected to GB, DS or laparotomy (controls, and monitored by an open-circuit indirect calorimeter composed of comprehensive laboratory animal monitoring system and adiabatic bomb calorimeter. RESULTS: Body weight loss was greater after DS than GB. Food intake was reduced after DS but not GB. Energy expenditure was increased after either GB or DS. Fecal energy content was increased after DS but not GB. CONCLUSION: GB induced body weight loss by increasing energy expenditure, whereas DS induced greater body weight loss by reducing food intake, increasing energy expenditure and causing malabsorption in rat models.

  18. Disturbance and recovery of trunk mechanical and neuromuscular behaviours following repetitive lifting: influences of flexion angle and lift rate on creep-induced effects.

    Science.gov (United States)

    Toosizadeh, Nima; Bazrgari, Babak; Hendershot, Brad; Muslim, Khoirul; Nussbaum, Maury A; Madigan, Michael L

    2013-01-01

    Repetitive lifting is associated with an increased risk of occupational low back disorders, yet potential adverse effects of such exposure on trunk mechanical and neuromuscular behaviours were not well described. Here, 12 participants, gender balanced, completed 40 min of repetitive lifting in all combinations of three flexion angles (33, 66, and 100% of each participant's full flexion angle) and two lift rates (2 and 4 lifts/min). Trunk behaviours were obtained pre- and post-exposure and during recovery using sudden perturbations. Intrinsic trunk stiffness and reflexive responses were compromised after lifting exposures, with larger decreases in stiffness and reflexive force caused by larger flexion angles, which also delayed reflexive responses. Consistent effects of lift rate were not found. Except for reflex delay no measures returned to pre-exposure values after 20 min of recovery. Simultaneous changes in both trunk stiffness and neuromuscular behaviours may impose an increased risk of trunk instability and low back injury. An elevated risk of low back disorders is attributed to repetitive lifting. Here, the effects of flexion angle and lift rate on trunk mechanical and neuromuscular behaviours were investigated. Increasing flexion angle had adverse effects on these outcomes, although lift rate had inconsistent effects and recovery time was more than 20 min.

  19. Selective action of an atypical neuroleptic on the mechanisms related to the development of cocaine addiction: a pre-clinical behavioural study.

    Science.gov (United States)

    Marinho, Eduardo A V; Oliveira-Lima, Alexandre J; Wuo-Silva, Raphael; Santos, Renan; Baldaia, Marilia A; Hollais, André W; Longo, Beatriz M; Berro, Laís F; Frussa-Filho, Roberto

    2014-04-01

    An increased function in the mesolimbic dopaminergic system has been extensively associated with the rewarding effects of both natural stimuli and drugs of abuse. Thus, dopamine receptor blockers, such as neuroleptic drugs, can be proposed as candidates for potential therapeutic approaches to treat drug dependence. Notwithstanding, this therapeutic potential of neuroleptics critically depends on a selective action on the specific mechanisms related to the development of addiction. We compared the effects of different doses of haloperidol, ziprasidone and aripiprazole (first-, second- and third-generation neuroleptics, respectively) on spontaneous locomotor activity of mice in a novel environment, hyperlocomotion induced by acute cocaine administration and cocaine-induced locomotor sensitization by a two-injection protocol. Whereas high doses of haloperidol abolished the three behavioural paradigms without selectivity, low doses of ziprasidone selectively abolished the development of the behavioural sensitization phenomenon. Finally, low doses of aripiprazole inhibited acute cocaine-induced hyperlocomotion and behavioural sensitization without modifying spontaneous locomotor activity. Thus, aripiprazole at lower doses was the most selective antipsychotic drug concerning the inhibition of the development of behavioural sensitization to cocaine. Because locomotor sensitization in rodents has been proposed to share plastic mechanisms with drug addiction in humans, our data provide relevant suggestions to the clinical practice.

  20. Duodenal intraepithelial T lymphocytes in patients with functional dyspepsia

    Institute of Scientific and Technical Information of China (English)

    Gilles Gargala; Stéphana Lecleire; Arnaud Frangois; Serge Jacquot; Pierre Déchelotte; Jean Jacques Ballet; Loic Favennec; Philippe Ducrotté

    2007-01-01

    AIM:To quantify the intraepithelial lymphocytes (IELs) and to document the membrane expression of CD4,CD8,TCRγδ and adhesion and/or activation-associated molecules (CD103,CD28,CD44,CD69,HLA-DR,CD95/Fas) in the duodenal mucosa of patients with functional dyspepsia (FD) in order to provide arguments for an immunological process in FD.METHODS:Twenty-six FD patients according to Rome Ⅱ criteria (20 were H pylori negative) were studied and compared to 12 healthy adults.IELs were isolated from five duodenal biopsy samples,then quantified by microscopy and flow cytometry while the membrane phenotypes were determined by cytofluorometry.RESULTS:Duodenal histological examination was normal.In H pylori negative patients,the number of IELs was not different from that in healthy controls.Median percentage expression of CD4,CD8,or TCRγδ and CD103,CD44,CD28,CD69 on CD3+ IELs,among the adhesion/activation associated molecules tested,was not different from that in healthy controls.In contrast,the median percentage expression of CD95/Fas [22(9-65) vs 45(19-88),P=0.03] and HLADR expressing CD3+ IELs [4(0-30) vs 13(4-42),P=0.041 was signifcantly lower in the H pylori negative FD group than in healthy controls,respectively.The number of IELs was significantly greater in H pylori positive FD patients than in healthy controls [median ratio for 100 enterocytes 27.5 (6.7-62.5) vs 10.8 (3-33.3), P = 0.02] due to a higher number of CD8+ CD3+ IELs.CONCLUSION: In H pylori negative FD patients, the phenotypic characterization of IELs suggests that we cannot exclude a role of IELs in FD.

  1. Tests and analysis of mechanical behaviours of rock bolt components for China’s coal mine roadways

    Institute of Scientific and Technical Information of China (English)

    Hongpu Kang; Jinghe Yang; Xianzhi Meng

    2015-01-01

    A series of laboratory tests were performed to study the mechanical behaviours of newly developed high strength rock bolt components, including rebar, thread, plate, and domed washer. The characteristics of deformation and damage of each component were presented. The stress distribution of plate and domed washer was investigated through finite element modelling. The numerical results show that the yield and tensile strengths of the developed high strength rebar are 33.6%e58.3% and 17.2%e28.7% greater than those of the conventional rebar, respectively. The increase in yield strength was higher than that in tensile strength, suggesting an increase in yield to tensile strength ratio and a decrease in elongation. It is well-known that the thread processing may not be of high precision and accuracy as expected, which is characterised as rough thread surface, non-identical tooth height, toe stripping, and cracks in the surface. Hardening during thread processing tends to increase the thread yield and tensile strengths. In this paper, the typical deformation process of arch-shaped plate is classified into five stages. The tested plates exhibited distinct deformation characteristics and bearing capacities due to variations in shape, size, material and presence of washer. It was observed that uneven bottom surface, low bearing arch and large radius of the transitional arc connecting bearing arch and bottom surface were the major reasons ac-counting for low load-bearing capacity of plates. The performance of domed washer has a close relation with the shape, size, strength, and deformation compatibility with plate. Stress concentration was observed on the periphery of the contact surface between domed washer and plate, which is significantly influenced by the strength of domed washer and is considered to be 20%e30%higher than that of plate. Finally, a case study in the Datong coal mining district was presented, and the support pattern and effect of the developed rock bolt

  2. Analysis of the moisture effect on the mechanical behaviour of an adhesively bonded joint under proportional multi-axial loads

    OpenAIRE

    Arnaud, N.; Creac' Hcadec, R; Cognard, J. Y.; Davies, Peter; Le Gac, Pierre-Yves

    2015-01-01

    The objective of the study is to identify the 3D behaviour of an adhesive in an assembly, and to take into account the effect of ageing in a marine environment. To that end, three different tests were employed. Gravimetric analyses were used to determine the water diffusion kinetics in the adhesive. Bulk tensile tests were performed to highlight the effects of humid ageing on the adhesive behaviour. Modified Arcan tests were performed for several ageing times to obtain the experimental databa...

  3. Microcirculatory remodeling in marginal zone of duodenal ulcer after bleeding

    Directory of Open Access Journals (Sweden)

    Sulayeva О.N.

    2009-01-01

    Full Text Available To estimate objectively vessels network remodeling in duodenal mucosa after ulcer bleeding the morphometric analysis of marginal ulcer zone biopsies was performed in 32 patients. It was shown that reparation is accompanied with chronic inflammation and acute alteration of microcirculation. Injection hemostasis led to enhancement of microcirculation, development of edema and ischemic alteration of mucosal tissues. Acute neutrophilic infiltration during 1 day was changed on 3 day with granular tissue development and angiogenesis stimulation. Intensification and prolongation of angiogenesis paral-leled with lymphocytes infiltration after 7 days resulted to villi dysmorphogenesis and changes in cellular content of intestinal epithelium.

  4. Intraoperative methods to stage and localize pancreatic and duodenal tumors.

    Science.gov (United States)

    Norton, J A

    1999-01-01

    Intraoperative methods to stage and localize tumors have dramatically improved. Advances include less invasive methods to obtain comparable results and precise localization of previously occult tumors. The use of new technology including laparoscopy and ultrasound has provided some of these advances, while improved operative techniques have provided others. Laparoscopy with ultrasound has allowed for improved staging of patients with pancreatic cancer and exclusion of patients who are not resectable for cure. We performed laparoscopy with ultrasound on 50 consecutive patients with adenocarcinoma of the pancreas or liver who appeared to have resectable tumors based on preoperative computed tomography. 22 patients (44%) were found to be unresectable because of tumor nodules on the liver and/or peritoneal surfaces or unsuspected distant nodal or liver metastases. The site of disease making the patient unresectable was confirmed by biopsy in each case. Of the 28 remaining patients in whom laparoscopic ultrasound predicted to be resectable for cure, 26 (93%) had all tumor removed. Thus laparoscopy with ultrasound was the best method to select patients for curative surgery. Intraoperative ultrasound (IOUS) has been a critical method to identify insulinomas that are not palpable. Nonpalpable tumors are most commonly in the pancreatic head. Because the pancreatic head is thick and insulinomas are small, of 9 pancreatic head insulinomas only 3 (33%) were palpable. However, IOUS precisely identified each (100%). Others have recommended blind distal pancreatectomy for individuals with insulinoma in whom no tumor can be identified. However, our data suggest that this procedure is contraindicated as these occult tumors are usually within the pancreatic head. Recent series suggest that previously missed gastrinomas are commonly in the duodenum. IOUS is not able to identify these tumors, but other methods can. Of 27 patients with 31 duodenal gastrinomas, palpation identified 19

  5. Peptic Ulcer Disease Different Pathogenesis of Duodenal and Gastric Ulcer

    Directory of Open Access Journals (Sweden)

    Hendra Koncoro

    2015-12-01

    Full Text Available Despite decrease frequency of Helicobacter pylori (H. pylori due to eradication therapy, peptic ulcer disease as a manifestation of this infection is still remain a health burden. Understanding the physiology of gastric acid secretion and its alteration by H. pylori induced inflammation will aid physician in differentiating peptic ulcer disease based on its location. Duodenal ulcer and gastric ulcer disease are two common condition that usually found in peptic ulcer. Recognition of symptoms and its pathogenesis may lead physician to understand the fate of each condition in the future. This article reviews concept of peptic ulcer pathogenesis according to ulcer etiology.

  6. Gallstone ileus of duodenum with huge duodenal stone

    Directory of Open Access Journals (Sweden)

    Mohammad Ehsan

    2006-12-01

    Full Text Available Gastrointestinal obstruction by a gallstone is an uncommon but important complication of biliary stone disease which mostly affects the elderly. The classic triad of radiological features includes pneumobilia, ectopic gallstone and evidence of intestinal obstruction. Terminal ileum is the most common site of obstruction, followed by jejunum and gastric outlet. We present a case of duodenal gallstone ileus of a large, fluid-density mixed biliary stone with a peripheral rim of hyperdensity (very fine calcification in CT scan. KEY WORDS: Gallstone ileus, duodenum, intestinal obstruction.

  7. SUPERIOR MESENTERIC ARTERY SYNDROME - AN UNUSUAL CAUSE OF DUODENAL OBSTRUCTION

    OpenAIRE

    Sahu SK, , , , , , ,; Singh PK; Ray J; Uniyal M; Sharma C; Sekhar C; Kapruwan H; Sachan PK

    2012-01-01

    Superior mesenteric artery (SMA) arising from aorta at the level of first lumbar vertebra usually takes an angular downward course from ventral surface of aorta. It is through this vascular angle that the 3rd part of duodenum passes at the level of 4th lumbar vertebra. Fat and lymphatics around SMA maintains the angle at 25° to 60° with a mean of 450 and provide protection against duodenal compression. In Superior Mesenteric Artery Syndrome, the SMA-aorta angle in narrowed down to 7° to 22° w...

  8. MULTIPLE ASSOCIATED ANOMALIES IN PATIENTS OF DUODENAL ATRESIA: A CASE SERIES

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    Bilal Mirza

    2012-04-01

    Full Text Available Duodenal atresia has been reported in association with various malformations and syndromes common being Down syndrome, malrotation, and annular pancreas. Its association with multiple anomalies is rare and scarcely reported in literature. Herein 3 cases of duodenal atresia associated with multiple congenital anomalies are being reported.

  9. Upper gastrointestinal bleeding from duodenal vascular ectasia in a patient with cirrhosis

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    We report a cirrhotic patient with duodenal vascular ectasia and spontaneous bleeding. The bleeding was successfully controlled with argon plasma coagulation.Duodenal vascular ectasia may be a cause of upper gastrointestinal bleeding in patients with cirrhosis, and argon plasma coagulation may be effective and safe to achieve hemostasis of this lesion.

  10. [The prognostic value of gastric metaplasia in the duodenal mucosa in patients with Helicobacter pylori positive duodenal bulb ulcer].

    Science.gov (United States)

    Marshalko, O V; Konorev, M R

    2008-01-01

    The predictive value of gastric metaplasia in the duodenal mucosa in patients Helicobacter pylori-positive patients with duodenal bulb ulcer (DBU) was investigated. One hundred and twenty four randomly selected patients with DBU were included in this prospective study. The detection of Helicobacter pylori (HP) in the stomach and duodenum was carried out with Giemsa (using standard visual analogue scale), rapid urease test (standard Jatrox-HP test, Rohm Pharma, Germany), and polymerase chain reaction (PCR) to detect the specific fragment of ureC HP gene (Helicopol II, Lytech, Russia). Regions of gastric metaplasia of the duodenum were confirmed by periodic acid-Schiff and alcian blue (Serva) staining (pH 1.0; 2.5) Duodenal ulcer (DU) complications were registered within 8 to 10 years. Estimation of the predictive factor (gastric metaplasia in the duodenum) was carried out in patients with non-complicated DU (Group 1; n = 73), and with such complications as bleeding, perforation, penetration, pyloroduodenal stenosis (Group 2; n = 51) which were revealed within the 8 to 10 years of observation. Gastric metaplasia in the duodenum was found in 64 or 87.7% of the 73 patients with non-complicated DU and in 5 or 9.8% of the 51 patients with complicated DU within 8 to 10 years of observation. The following facts about the predictive factor for the prognosis of DU complication were found: the sensitivity of 83.6%, the specificity of 92.8%, the predictive accuracy of 88.7%, the relative risk of the predicted outcome of 7.5, the relative risk of a different outcome of 0.11, the odds ration of 65.4. The study revealed a high and significant (p gastric metaplasia in the duodenum as a marker of non-complicated clinical course of DU in HP-positive patients within an 8 to 10-year period.

  11. Endoscopic Management of a Primary Duodenal Carcinoid Tumor

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    Albin Abraham

    2012-03-01

    Full Text Available Carcinoids are rare, slow-growing tumors originating from a variety of different neuroendocrine cell types. They are identified histologically by their affinity for silver salts and by positive reactions to neuroendocrine markers such as neuron-specific enolase, synaptophysin and chromogranin. They can present with various clinical symptoms and are difficult to diagnose. We present the case of a 43-year-old woman who was referred for evaluation of anemia. Upper endoscopy showed a duodenal bulb mass around 1 cm in size. Histopathological and immunohistochemistry staining were consistent with the diagnosis of a carcinoid tumor. Further imaging and endoscopic studies showed no other synchronous carcinoid lesions. Endoscopic ultrasound (EUS revealed a 1 cm lesion confined to the mucosa and no local lymphadenopathy. Successful endoscopic mucosal resection of the mass was performed. Follow-up surveillance 6 months later with EUS and Octreoscan revealed no new lesions suggestive of recurrence. No consensus guidelines exist for the endoscopic management of duodenal carcinoid tumors. However, endoscopic resection is safe and preferred for tumors measuring 1 cm or less with no evidence of invasion of the muscularis layer.

  12. Further experience with epigastric pain reproduction test in duodenal ulceration.

    Science.gov (United States)

    Earlam, R J

    1972-06-17

    Further evidence is presented that the epigastric pain of duodenal ulceration, situated between the rib margins and just below the xiphisternum, arises from the lower oesophagus.One-hundred patients with duodenal ulceration were divided into those with epigastric pain (61) and those with pain in the upper abdomen but not in the epigastrium (39). Perfusion of 0.1 N HCl into the lower oesophagus reproduced epigastric pain in 53 of the 61 with epigastric pain (mean 37 ml) but in none of the 39 without (mean 125 ml). All those who had been woken by epigastric pain at night in the previous four weeks had a positive test.In five the test remained positive even though the acid was neutralized by a continuous perfusion of alkali just below the gastro-oesophageal junction. In another five 200 ml 0.1 N HCl instilled into the stomach for 21 minutes did not reproduce epigastric pain, even though 30 ml perfused for three minutes into the lower oesophagus did.

  13. Duodenal pseudomelanosis (pseudomelanosis duodeni: a rare endoscopic finding

    Directory of Open Access Journals (Sweden)

    Aloísio Felipe-Silva

    2011-12-01

    Full Text Available Duodenal pseudomelanosis (or pseudomelanosis duodeni is a rare benigncondition characterized by black-brown speckled pigmentation of the duodenalmucosa. Collections of pigment−laden macrophages are found in the tips ofduodenal villi. The pigment is thought to be mostly composed of ferrous sulfide.Histochemichal stains for iron (Perl’s prussian blue or melanin (Masson-Fontana may be positive, but are usually negative or unpredictable. Duodenalpseudomelanosis occurs predominantly in middle-aged to old adults andmore commonly in females. It is associated with chronic renal failure, arterialhypertension, diabetes mellitus and gastrointestinal bleeding. Medications suchas ferrous sulfate, hydralazine, propranolol, hydrochlorothiazide and furosemideare thought to play a role as well. We report a case of a 86-year-old femalewho presented with a history of watery diarrhea and melena. The patient had ahistory of high blood pressure and ischemic stroke episodes. She was on multiplemedication including hidralazine, captopril, hydrochlorthiazide and aspirin. She wasdehydrated, her blood pressure was 96 × 60 mmHg and neurologic examinationshowed complete left hemiplegia with central VII nerve palsy. Laboratory testsshowed normal serum electrolytes and renal function. Hemoglobin level was10.7 g%. An upper endoscopy showed multiple diminutive black spots throughoutthe distal duodenal bulb and second portion. Histology showed multiple foci ofa brown-black granular pigment inside macrophages within the tips of the villi(pseudomelanosis. Stains for iron and melanin were negative. She was treatedwith omeprazol, parenteral fluid replacement with saline and partial fasting. Aftercomplete recovery she was discharged for ambulatory follow up.

  14. Roxatidine acetate in the long term maintenance of duodenal ulcers.

    Science.gov (United States)

    Brunner, G

    1988-01-01

    A non-comparative multicentre study of 105 patients with healed duodenal ulcers was conducted to determine the effect on ulcer recurrence of 6 months' maintenance treatment with roxatidine acetate 75 mg daily. All patients had previously received roxatidine acetate treatment. 31 patients out of 89 had 32 relapsed ulcers after 6 months of treatment, which represents an overall relapse rate of around 30%; the relapse rate in smokers was double that of non-smokers. The overall incidence of epigastric pain did not increase significantly over the period of the trial, although some patients complained of mild pain when they entered the study despite having endoscopically confirmed healed ulcers. At the end of the study continuous poor appetite and pyrosis were reported by 17% and 6% of patients, respectively. Side effects, which included constipation and diarrhoea, were reported by 4 patients, 1 of whom withdrew from therapy. There were no clinically significant changes in laboratory values. Thus, maintenance treatment with roxatidine acetate 75 mg daily proved a safe and effective method of preventing symptomatic duodenal ulcer relapse.

  15. Giant Brunner’s Gland Adenoma of the Duodenal Bulb Presenting with Ampullary and Duodenal Obstruction Mimicking Pancreatic Malignancy

    Directory of Open Access Journals (Sweden)

    Vishal Gupta

    2011-07-01

    Full Text Available Context Brunner’s gland adenoma is a rare benign duodenal neoplasm. It usually presents with luminal obstruction or gastrointestinal bleeding. In rare cases, it may mimic a pancreatic malignancy and may present with obstructive jaundice. Case report A 65-year-old female presented with a two-month history of abdominal pain, early satiety and retrosternal burning pain. Liver function tests showed elevated enzymes with normal bilirubin. Imaging studies revealed a large mass in relation to the uncinate process of the pancreas and the distal duodenum along with the dilated common bile duct and the main pancreatic duct. Initial endoscopic evaluation failed to make a correct diagnosis. Repeat endoscopic evaluation combined with endoscopic sonography, however, revealed a large polypoid mass arising from the duodenal bulb. The patient underwent a transduodenal polypectomy. A diagnosis of Brunner’s gland adenoma was made on histopathological examination. Conclusion Giant Brunner’s adenoma may have unusual presentations. It may present with the features of ampullary obstruction mimicking periampullary or pancreatic malignancies. Extensive preoperative evaluation is required to reach a correct diagnosis in order to avoid more extensive surgery.

  16. Patients with Helicobacter pylori positive and negative duodenal ulcers have distinct clinical characteristics

    Institute of Scientific and Technical Information of China (English)

    Kent-Man Chu; Ka-Fai Kwok; Simon Law; Kam-Ho Wong

    2005-01-01

    AIM: To assess the clinical characteristics of Helicobacterpylori(H pylori) negative duodenal ulcer.METHODS: Patients with an endoscopic diagnosis of duodenal ulcer between 1996 and 2002 were included in the present study. Patients were considered to be negative for Hpylori, if both histological examination and rapid urease test of biopsy specimens were negative. A comparison was made between patients with H pyloripositive and negative duodenal ulcers.RESULTS: A total of 1 343 patients were studied. Their mean age was 54.7±0.5 years. There was a male preponderance (M:F = 2.5:1). Three hundred and ninetyeight patients (29.6%) did not have H pylori infection. The annual proportion of patients with H pylori negative duodenal ulcers increased progressively from 1996 to2002. On multivariate analysis, patients with H pylorinegative duodenal ulcer were more likely to be older, have concomitant medical problem, pre-existing malignancy, recent surgery, underlying sepsis, or taken non-steroidal anti-inflammatory drugs. In terms of clinical presentations, patients with H pylori negative duodenal ulcer were more likely to present with bleeding, multiple ulcers and larger ulcers.CONCLUSION: The proportion of patients with H pylori negative duodenal ulcers is on the rise because of a continued drop in incidence of H pylori positive duodenalulcers in recent years. Such patients have distinct clinical characteristics and it is important to ascertain the H pylori status before starting eradication therapy.

  17. Regulation of duodenal bicarbonate secretion during stress by corticotropin-releasing factor and beta-endorphin.

    Science.gov (United States)

    Lenz, H J

    1989-02-01

    Proximal duodenal mucosal bicarbonate secretion is an important factor in the pathogenesis of duodenal ulcer disease. To examine the central nervous system regulation of duodenal bicarbonate secretion, an animal model was developed that allowed cerebroventricular and intravenous injections as well as collection of duodenal perfusates in awake, freely moving rats. The hypothalamic peptide corticotropin-releasing factor (CRF) and stress (physical restraint) significantly stimulated duodenal bicarbonate secretion. These responses were abolished by pretreatment of the animals with the CRF receptor antagonist alpha-helical CRF-(9-41), hypophysectomy, and naloxone. In contrast, blockade of autonomic efferents by surgical and pharmacological means did not prevent the stimulatory effects of stress and CRF. Intravenous, but not cerebroventricular, administration of beta-endorphin that produced plasma concentrations of beta-endorphin that were similar to those produced by exogenous CRF and stress significantly stimulated duodenal bicarbonate secretion. These results indicate that endogenous CRF released during stress and exogenously administered CRF stimulate duodenal bicarbonate secretion by release of beta-endorphin from the pituitary, thus, demonstrating a functional hypothalamus-pituitary-gut axis.

  18. Effects of omeprazole and eradication of Helicobacter pylori on gastric and duodenal mucosal enzyme activities and DNA in duodenal ulcer patients.

    Science.gov (United States)

    Vetvik, K; Schrumpf, E; Mowinckel, P; Aase, S; Andersen, K J

    1994-11-01

    Duodenal and gastric content of mucosal enzymes in duodenal ulcer (DU) patients differs from that of controls. The purpose of this study has been to examine the effect of omeprazole and eradication of Helicobacter pylori on mucosal enzymes in DU patients. The enzyme activities of seven gastric and duodenal mucosal marker enzymes from the brush border, lysosomes, and mitochondria have been studied. In study I the measurements were made in 29 patients with an active DU before and after 14 days of omeprazole treatment. In study II 22 duodenal ulcer patients were given bismuth subnitrate, oxytetracycline, and metronidazole (triple therapy) for 2 weeks to eradicate H. pylori. Biopsy specimens were taken from the duodenum and the stomach for enzyme measurements and histologic assessment. In study II additional specimens were obtained from the prepyloric region for urease tests and culture of H. pylori. The ulcer healing rates were more than 90% after both omeprazole and triple therapy. H. pylori was eradicated in 86% after triple therapy. The activities of the brush-border enzymes lactase, neutral-alpha-glucosidase, alkaline phosphatase, leucyl-beta-naphthylamidase, and gamma-glutamyltransferase (gamma-GT) increased significantly in the duodenal bulb and the descending duodenum during treatment with omeprazole. No changes in duodenal enzyme activity were detected after triple therapy, whereas a significant fall in gamma-GT and acid phosphatase activities was seen in the stomach. The mucosal DNA in the gastric antrum decreased both after treatment with omeprazole and after triple therapy. A similar decrease in mucosal DNA of the gastric antrum was demonstrated after both omeprazole and triple therapy with bismuth subnitrate, oxytetracycline, and metronidazole. Omeprazole also affects the content of duodenal mucosal enzymes, whereas triple therapy particularly affects the gastric mucosal enzyme activity.

  19. Prevalence of non- Helicobacter pylori duodenal ulcer in Karachi,Pakistan

    Institute of Scientific and Technical Information of China (English)

    Javed Yakoob; Wasim Jafri; Nadim Jafri; Muhammad Islam; Shahab Abid; Saeed Hamid; Hasnain AliShah; Hizbullah Shaikh

    2005-01-01

    AIM: To determine the prevalence of non-Helicobacter pylori (H pylori)-related duodenal ulcer in patients with acid-peptic diseases.METHODS: Medical records of patients who attended the Gastroenterology Department at Aga Khan University Hospital from 1999 to 2001 and had endoscopic diagnosis of duodenal ulcers were reviewed. Duodenal ulcer associated with H pylori was diagnosed on the basis of endoscopy,rapid urease test and histopathology whereas histories of aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs) related duodenal ulcers. Non-H pylori, non-NSAID duodenal ulcers were those without H pylori infection and history of NSAID intake. Co-morbid conditions associated were noted.RESULTS: Of 2 260 patients, 10% (217/2 260) had duodenal ulcer. Duodenal ulcer related to H pylori infectionaccounted for 53% (116/217), NSAID-related 10% (22/217),non-H pylori non-NSAID 29% (62/217), and 8% (17/217) had both Hpyloriinfection and histories of NSAID intake. Fifteen percent (18/116)_patients had past histories of peptic ulcer disease in Hpyloriinfection, while 8% (5/62) in non-Hpylorinon-NSAID ulcer. Co-morbid conditions in H pylori infection were seen in 23% (27/116) and 34%(21/62) in non-H pylori non-NSAID ulcer.CONCLUSION: Incidence of H pylori infection related with duodenal ulcer is common. In the presence of co-morbids, non-Hpyloriand non-NSAID duodenal ulcer is likely to be present.

  20. Proteomic analysis of Eimeria acervulina sporozoite proteins interaction with duodenal epithelial cells by shotgun LC-MS/MS.

    Science.gov (United States)

    Zhang, ZhenChao; Wang, Shuai; Huang, JingWei; Liu, LianRui; Lu, MingMin; Li, MengHui; Sui, YuXia; Xu, LiXin; Yan, RuoFeng; Song, XiaoKai; Li, XiangRui

    2015-08-01

    Although it has been known for many years that Eimeria acervulina (E. acervulina) initiates infection by invading the duodenal epithelial cells of chicken, the key protein molecules and the mechanisms of the parasite in invading are unknow. In this study, we found that 85 proteins of E. acervulina could bind with the chicken duodenal epithelial cells from Eimeria protein database. Among them, sixteen were identified only in Eimeria spp. correlation with invasion and evasion and 69 proteins were found in Eimeria spp. with more than 2 unique pep count. Nine out of the 16 proteins and 41 out of the 69 proteins were annotated according to Gene Ontology Annotation in terms of molecular function, biological process, and cellular localization. Most of the 9 annotated proteins occurred in binding, catalytic activity and cellular process whereas, 29 (70.73%) out of the 41 proteins had binding activity and 20 proteins (48.78%) had catalytic activity. The findings provided an insight into the interactive relationship between E. acervulina and host cells and will shed new lights on the understanding of molecular mechanisms of E. acervulina invasion and pathogenesis.

  1. Study of the hydro-mechanical behaviour of expanded graphite gaskets; Etude du comportement et de l`etancheite de joints en graphite expnase

    Energy Technology Data Exchange (ETDEWEB)

    Patron, E. [Electricite de France (EDF), Direction des Etudes et Recherches, 92 - Clamart (France)

    1997-12-31

    The poro-mechanical behaviour models developed by O. Coussy permit to consider various phenomena observed experimentally: thermo-hydro-mechanical couplings, plasticity, etc. The aim of this study is to implement the simplest poro-mechanical model (i.e. the isotropic linear poro-elastic model) to model the gasket hydro-mechanical behaviour. First, isotropic poro-elastic characteristics of expanded graphite have been estimated from these tests conducted at Departement Mecanique et Technologie des Composants (MTC) and data from literature. Then, analytical solutions of the tightness tests developed at the MTC Department have been carried out. These calculations provide a first estimation of porosity variations during a tightness tests with metal/metal contact or in elastic recovery, and during a `hot thermal transient`. Thickness controlled numerical calculations have proved the analytical calculations relevance. With regard to simulation of tests with metal/metal contact or `hot thermal transient`, stress controlled numerical calculations have pointed out: - a greater vertical displacement on the inner side of the graphite ring and - a z dependence of the radial displacement and thus a porous differential variation between the upper and lower faces of the ring. (author). 21 refs.

  2. Congenital duodenal obstruction with situs inversus totalis: Report of a rare association and discussion

    Directory of Open Access Journals (Sweden)

    Sharma Satendra

    2008-01-01

    Full Text Available This report is to present and discuss an extremely rare association of situs inversus with duodenal atresia in an 11-day-old male neonate born full term and weighing 1.9 kg. The baby presented with recurrent bilious vomiting. Babygram revealed situs inversus and duodenal obstruction. Echocardiography showed dextrocardia with a small ASD. Exploration confirmed a duodenal diaphragm with a central perforation between the third and fourth part of the duodenum and situs inversus. The literature search revealed 20 cases reported so far.

  3. First case reported of Bouveret's syndrome associated to duodenal and biliary perforation to retroperitoneum

    Directory of Open Access Journals (Sweden)

    María Victoria Vieiro-Medina

    Full Text Available We present the case of a 69 year old woman with a history of cholecystitis, who consulted for severe abdominal pain, nausea and vomiting. Abdominal CT showed duodenal obstruction caused by a gallstone, cholecystoduodenal fistula and pneumobilia, what is known as Bouveret's syndrome, a rare form of gallstone ileus. Additionally, she presented free duodenal and vesicular perforation to retroperitoneum at the same level of the cholecystoduodenal transit point. The patient underwent a difficult cholecystectomy, enterolithotomy, repair of the duodenal defect, extensive washing and drainage of the retroperitoneum. The postoperative course was uneventful except for a laparotomy infection.

  4. Upper gastrointestinal hemorrhage due to duodenal stromal tumor

    Directory of Open Access Journals (Sweden)

    Parreira José Gustavo

    2003-01-01

    Full Text Available BACKGROUND: Gastrointestinal stromal tumor represents a rare neoplasm that originates in the muscular wall of the hollow viscera. AIM: To report gastrointestinal stromal tumor as a source of upper gastrointestinal bleeding, which required urgent surgical control. PATIENT/METHOD: A man with 61 years old was admitted to the emergency service sustaining hematemesis and melena. Endoscopy showed active bleeding from a tumor in the second portion of the duodenum, which was controlled by heater probe cauterization. Surgery was performed through a median laparotomy. A local resection of a 4 cm tumor in the second portion of the duodenum was carried out, together with a primary end-to-end anastomosis and a duodenal diverticulization. No complications happened during the post-operative period. Morphologic examination showed gastrointestinal stromal tumor with no atypical mitosis and a preserved capsule. CONCLUSION: Albeit not being common, gastrointestinal stromal tumors can represent a source of substantial gastrointestinal hemorrhage.

  5. Functional characterization of serotonin receptor subtypes in human duodenal secretion

    DEFF Research Database (Denmark)

    Engelmann, Bodil Elisabeth; Bindslev, Niels; Poulsen, Steen Seier;

    2006-01-01

    of dyspeptic patients with or without Helicobacter pylori infection, and to determine the 5-HT receptor subtypes functionally involved. Biopsies from the second part of duodenum were obtained from 43 dyspeptic patients during routine endoscopy. Biopsies were mounted in modified Ussing chambers with air suction......: ketanserin, ondansetron, or SB-204070 (1-butyl-4 piperidinmethyl-8-amino-7-chloro-2,3-dihydro-1,4-benzodioxin-5-carboxylate HCl). Histological examination was performed on duodenal biopsies. Helicobacter urease testing and histological examination determined Helicobacter pylori infection. 5-HT induced a dose......-dependent and bumetanide-sensitive short-circuit current, which was independent of the presence of Helicobacter pylori infection. All the three 5-HT receptor antagonists failed to significantly effect basal and 5-HT-induced short-circuit current. Our results indicate that in human duodenum 1) 5-HT is a potent stimulator...

  6. Duodenal perforation as result of blunt abdominal trauma in childhood.

    Science.gov (United States)

    Hartholt, Klaas Albert; Dekker, Jan Willem T

    2015-12-23

    Blunt abdominal trauma may cause severe intra-abdominal injuries, while clinical findings could be mild or absent directly after the trauma. The absence of clinical findings could mislead physicians into underestimating the severity of the injury at the primary survey, and inevitably leads to a delay in the diagnosis. The Blunt Abdominal Trauma in Children (BATiC) score may help to identify children who are at a high risk for intra-abdominal injuries in an early stage and requires additional tests directly. A case of a 10-year-old girl with a duodenal perforation after a blunt abdominal trauma is presented. A delay in diagnosis may lead to an increased morbidity and mortality rate. A low admission threshold for children with abdominal pain after a blunt trauma is recommended.

  7. [Effects of halothane and isoflurane on the canine duodenal paraneurons].

    Science.gov (United States)

    Sato, K; Noguchi, R; Taga, K; Shimoji, K; Fujita, T

    1988-05-01

    Administration of amino acid solution (50 mM tryptophane and phenylalanine in saline) into the canine duodenum is known to cause an increase in pancreatic secretion. This response is mediated by the excitation of duodenal endocrine cells, paraneurons, which release cholecystokinin (CCK) into the systemic circulation in response to intraluminal amino acid stimuli. Pancreatic secretory cells are then evoked by the CCK in the blood to secrete the juice into the duodenum. The authors investigated the effects of two general anesthetics, halothane and isoflurane, on this response. Nine mongrel dogs were subjected to this study. Each dog underwent laparotomy under nitrous oxide (75%)-oxygen (25%) anesthesia with pancuronium (GO-Pb). The duodenal loop was exposed and two polyethylene cannulae (18Fr) were introduced into the loop. Proximal cannula was for the administration of the amino acid solution into the loop, and distal one was for drainage of the solution. The pancreatic duct was inserted with a polyethylene catheter, through which pancreatic juice was collected and measured for the volume and protein output by spectrophotometry. After these surgical procedures, the pancreatic secretory response to intraluminal amino acid stimuli was examined under GO-Pb (Control). Then halothane (1.0%) (Group 1, four dogs) or isoflurane (2.0%) (Group 2, five dogs) was administered for 30 min and the same response was tested. The pancreatic secretory response to intraluminal amino acid stimulus was suppressed by the surgical concentrations of both halothane (1.0%) and isoflurane (2.0%). Neither halothane nor isoflurane suppressed the pancreatic secretory response evoked by intravenous CCK infusion (10 Ivy Dog Units.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. Metallurgical and mechanical behaviours of PWR fuel cladding tube oxidised at high temperature; Comportements metallurqigue et mecanique des materiaux de gainage du combustible REP oxydes a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Stern, A

    2007-12-15

    Zirconium alloys are used as cladding materials in Pressurized Water Reactors (PWR). As they are submitted to very extreme conditions, it is necessary to check their behaviour and especially to make sure they meet the safety criteria. They are therefore studied under typical in service-loadings but also under accidental loadings. In one of these accidental scenarios, called Loss of Coolant Accident (LOCA) the cladding temperature may increase above 800 C, in a steam environment, and decrease before a final quench of the cladding. During this temperature transient, the cladding is heavily oxidised, and the metallurgical changes lead to a decrease of the post quench mechanical properties. It is then necessary to correlate this drop in residual ductility to the metallurgical evolutions. This is the problem we want to address in this study: the oxidation of PWR cladding materials at high temperature in a steam environment and its consequences on post quench mechanical properties. As oxygen goes massively into the metallic part - a zirconia layer grows at the same time - during the high temperature oxidation, the claddings tubes microstructure shows three different phases that are the outer oxide layer (zirconia) and the inner metallic phases ({alpha}(O) and 'ex {beta}') - with various mechanical properties. In order to reproduce the behaviour of this multilayered material, the first part of this study consisted in creating samples with different - but homogeneous in thickness - oxygen contents, similar to those observed in the different phases of the real cladding. The study was especially focused on the {beta}-->{alpha} phase transformation upon cooling and on the resulting microstructures. A mechanism was proposed to describe this phase transformation. For instance, we conclude that for our oxygen enriched samples, the phase transformation kinetics upon cooling are ruled by the oxygen partitioning between the two allotropic phases. Then, these materials

  9. Physiological and genetic correlates of boldness: characterising the mechanisms of behavioural variation in rainbow trout, Oncorhynchus mykiss.

    Science.gov (United States)

    Thomson, Jack S; Watts, Phillip C; Pottinger, Tom G; Sneddon, Lynne U

    2011-01-01

    Bold, risk-taking animals have previously been putatively linked with a proactive stress coping style whereas it is suggested shyer, risk-averse animals exhibit a reactive coping style. The aim of this study was to investigate whether differences in the expression of bold-type behaviour were evident within and between two lines of rainbow trout, Oncorhynchus mykiss, selectively bred for a low (LR) or high (HR) endocrine response to stress, and to link boldness and stress responsiveness with the expression of related candidate genes. Boldness was determined in individual fish over two trials by measuring the latency to approach a novel object. Differences in plasma cortisol concentrations and the expression of eight novel candidate genes previously identified as being linked with divergent behaviours or stress were determined. Bold and shy individuals, approaching the object within 180 s or not approaching within 300 s respectively, were evident within each line, and this was linked with activity levels in the HR line. Post-stress plasma cortisol concentrations were significantly greater in the HR line compared with the LR line, and six of the eight tested genes were upregulated in the brains of LR fish compared with HR fish. However, no direct relationship between boldness and either stress responsiveness or gene expression was found, although clear differences in stress physiology and, for the first time, gene expression could be identified between the lines. This lack of correlation between physiological and molecular responses and behavioural variation within both lines highlights the complexity of the behavioural-physiological complex.

  10. Analysis of the thermo-mechanical behaviour of the DEMO Water-Cooled Lithium Lead breeding blanket module under normal operation steady state conditions

    Energy Technology Data Exchange (ETDEWEB)

    Di Maio, P.A.; Arena, P. [Dipartimento di Energia, Ingegneria dell’Informazione e Modelli Matematici, Università di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Aubert, J. [CEA Saclay, DEN/DANS/DM2S/SEMT, 91191 Gif sur Yvette Cedex (France); Bongiovì, G. [Dipartimento di Energia, Ingegneria dell’Informazione e Modelli Matematici, Università di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Chiovaro, P., E-mail: pierluigi.chiovaro@unipa.it [Dipartimento di Energia, Ingegneria dell’Informazione e Modelli Matematici, Università di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Giammusso, R. [ENEA – C.R. Brasimone, 40032 Camugnano (Italy); Li Puma, A. [CEA Saclay, DEN/DANS/DM2S/SEMT, 91191 Gif sur Yvette Cedex (France); Tincani, A. [ENEA – C.R. Brasimone, 40032 Camugnano (Italy)

    2015-10-15

    Highlights: • A DEMO WCLL blanket module thermo-mechanical behaviour has been investigated. • Two models of the WCLL blanket module have been set-up adopting a code based on FEM. • The water flow domain in the module has been considered. • A set of uncoupled steady state thermo-mechanical analyses has been carried out. • Critical temperature is not overcome. Safety verifications are generally satisfied. - Abstract: Within the framework of DEMO R&D activities, a research cooperation has been launched between ENEA, the University of Palermo and CEA to investigate the thermo-mechanical behaviour of the outboard equatorial module of the DEMO1 Water-Cooled Lithium Lead (WCLL) blanket under normal operation steady state scenario. The research campaign has been carried out following a theoretical–computational approach based on the Finite Element Method (FEM) and adopting a qualified commercial FEM code. In particular, two different 3D FEM models (Model 1 and Model 2), reproducing respectively the central and the lateral poloidal–radial slices of the WCLL blanket module, have been set up. A particular attention has been paid to the modelling of water flow domain, within both the segment box channels and the breeder zone tubes, to simulate realistically the coolant-box thermal coupling. Results obtained are herewith reported and critically discussed.

  11. Normal villous architecture with increased intraepithelial lymphocytes: a duodenal manifestation of Crohn disease.

    Science.gov (United States)

    Patterson, Emily R; Shmidt, Eugenia; Oxentenko, Amy S; Enders, Felicity T; Smyrk, Thomas C

    2015-03-01

    To assess a possible association between inflammatory bowel disease (IBD) and the histologic finding in duodenal biopsy specimens of increased intraepithelial lymphocytes (IELs) with normal villous architecture. We identified all patients with duodenal biopsy specimens obtained between 2000 and 2010 showing increased IELs and normal architecture. Among the 74 such patients who also had IBD, we characterized the clinical features of IBD and reviewed all available upper gastrointestinal biopsy specimens. Fifty-eight patients had Crohn disease, 13 had ulcerative colitis, and three had IBD, type unclassified. No duodenal sample with increased IELs had other histologic features of IBD. Among gastric biopsy specimens from 34 patients with Crohn disease, nearly half (16) had focal gastritis. We propose that Crohn disease be included in the differential diagnosis for increased IELs with normal villous architecture in duodenal biopsy specimens, particularly when gastric biopsy specimens show focal gastritis. Copyright© by the American Society for Clinical Pathology.

  12. Computer simulation of flow and mixing at the duodenal stump after gastric resection

    Institute of Scientific and Technical Information of China (English)

    Nenad Filipovic; Aleksandar Cvetkovic; Velibor Isailovic; Zoran Matovic; Mirko Rosic; Milos Kojic

    2009-01-01

    AIM: To investigate the flow and mixing at the duodenal stump after gastric resection, a computersimulation was implemented.METHODS: Using the finite element method, two different Billroth ? procedure cases (A and B) were modeled. Case A was defined with a shorter and almost straight duodenal section, while case B has a much longer and curved duodenal section. Velocity,pressure and food concentration distribution were determined and the numerical results were compared with experimental observations.RESULTS: The pressure distribution obtained by numerical simulation was in the range of the recorded experimental results. Case A had a more favorable pressure distribution in comparison with case B.However, case B had better performance in terms of food transport because of more continual fooddistribution,as well as better emptying of the duodenal section.

  13. Increased tissue concentration of neuropeptide Y in the duodenal mucosa in coeliac disease

    Energy Technology Data Exchange (ETDEWEB)

    Sjoelund, K.; Ekman, R. (Lund Univ. (Sweden))

    1989-01-01

    Neuropeptide Y (NPY) is localized to intestinal nerve fibres, of which there are few in normal duodenal mucosa. In the duodenal mucosa of 10 patients with coeliac disease and in a control group of 21 patients with other gastrointestinal symptoms, but with normal function of the small intestine, we studied the frequency of such fibres by immunohistochemistry and the tissue concentration of NPY by radioimmunoassay. Patients with coeliac disease had an increased number of NPY nerve fibres and significantly elevated tissue concentrations compared with the control group. The eluted fractions obtained by high-pressure liquid chromatography of duodenal extracts showed the same immunoreactive components in the two groups. This study therefore suggested proliferation of the peptide-containing nerve system in coeliac disease. The increased NPY levels in the duodenal mucosa may be of functional significance for the disease symptoms. 24 refs.

  14. Chronic diarrhea due to duodenal candidiasis in a patient with a history of kidney transplantation.

    Science.gov (United States)

    Nouri-Majalan, Nader; Moghaddasi, Sarasadat; Qane, Mohammad Davud; Shefaie, Farzane; Masoumi Dehshiri, Roghayyeh; Amirbaigy, Mohammad Kassem; Baghbanian, Mahmoud

    2014-11-01

    Candida infection in the small intestine is uncommon. We report an unusual case of duodenal candidiasis that presented as chronic diarrhea in a patient who had previously undergone kidney transplantation. A 60-year-old man presented with profuse watery diarrhea that had lasted 6 months 13 years after kidney transplantation. Upper gastrointestinal endoscopy results indicated candidiasis within the esophagus and duodenum. Biopsy results revealed active duodenitis with hyphal and yeast forms of Candida overlying the duodenal epithelium in periodic acid Schiff staining. The patient was successfully treated with fluconazole. After 6 months of follow-up, the patient had no complaint of diarrhea. Duodenal candidiasis may be the result of chronic diarrhea in patients with a history of kidney transplantation.

  15. Massive duodenal variceal bleed; complication of extra hepatic portal hypertension: Endoscopic management and literature review

    Institute of Scientific and Technical Information of China (English)

    Christopher; Steevens; Maisa; Abdalla; Truptesh; H; Kothari; Vivek; Kaul; Shivangi; Kothari

    2015-01-01

    Bleeding from duodenal varices is reported to be a catastrophic and often fatal event. Most of the cases in the literature involve patients with underlying cirrhosis. However, approximately one quarter of duodenal variceal bleeds is caused by extrahepatic portal hypertension and they represent a unique population given their lack of liver dysfunction. The authors present a case where a 61-year-old male with history of remote crush injury presented with bright red blood per rectum and was found to have bleeding from massive duodenal varices. Injection sclerotherapy with ethanolamine was performed and the patient experienced a favorable outcome with near resolution of his varices on endoscopic follow-up. The authors conclude that sclerotherapy is a reasonable first line therapy and review the literature surrounding the treatment of duodenal varices secondary to extrahepatic portal hypertension.

  16. Modeling data for pancreatitis in presence of a duodenal diverticula using logistic regression

    Science.gov (United States)

    Dineva, S.; Prodanova, K.; Mlachkova, D.

    2013-12-01

    The presence of a periampullary duodenal diverticulum (PDD) is often observed during upper digestive tract barium meal studies and endoscopic retrograde cholangiopancreatography (ERCP). A few papers reported that the diverticulum had something to do with the incidence of pancreatitis. The aim of this study is to investigate if the presence of duodenal diverticula predisposes to the development of a pancreatic disease. A total 3966 patients who had undergone ERCP were studied retrospectively. They were divided into 2 groups-with and without PDD. Patients with a duodenal diverticula had a higher rate of acute pancreatitis. The duodenal diverticula is a risk factor for acute idiopathic pancreatitis. A multiple logistic regression to obtain adjusted estimate of odds and to identify if a PDD is a predictor of acute or chronic pancreatitis was performed. The software package STATISTICA 10.0 was used for analyzing the real data.

  17. [Functional state of the gastro-duodenal area in gastro-esophageal reflux disease].

    Science.gov (United States)

    Vakhrushev, Ia M; Potapova, L O

    2007-01-01

    The complex study of stomach and duodenal function was performed in 150 patients with GERD. It was revealed that 84,3% of patients had increased stomach acid-production. In GERD exacerbation we found the disturbance of gastric mucosa decreasing protective properties of esophageal, stomach and duodenal mucosa. The patients had increased intragastral and intraduodenal pressure leading to decreasing of closing function of pylorus. Due to dynamic gastroscintigraphy the slowing of stomach evacuation was revealed in 69,2% patients, the acceleration - in 7,7% patients. The prevalence of bradyperistalsis was found in elecrogastromyography. The role of hormones (gastrin, insulin, cortisol, thyrotrophin, thyroxin) in disorders of gastro-duodenal complex function was shown. The complex investigation of gastro-duodenal complex function opens the pathophysiologic base of GERD and these data may be used in the choice of adequate therapy.

  18. [A case of pancreatic and duodenal fistula after total gastrectomy successfully treated with coagulation factor XIII].

    Science.gov (United States)

    Nishino, Hitoe; Kojima, Kazuhiro; Oshima, Hirokazu; Nakagawa, Koji; Fumura, Masao; Kikuchi, Norio

    2013-11-01

    Pancreatic fistula( PF) is a challenging postoperative complication. We report a case of PF following gastrectomy successfully treated using intravenous coagulation factor XIII( FXIII).A 78-year-old man with early gastric cancer underwent total gastrectomy with Roux-en-Y reconstruction. PF developed postoperatively, following which, leakage from the duodenal stump was observed. Percutaneous drainage and re-operative surgery were performed. A somatostatin analogue, antibiotic drugs, and gabexate mesilate were administrated along with nutritional support. The pancreatic and duodenal fistula had been producing duodenal juice for over 30 days since the re-operative surgery. As suspected, reduced FXIII activity was confirmed in the patient. After administering FXIII for 5 days, the amount of duodenal juice from the fistula markedly reduced, and the fistula closed immediately afterwards. The results of our study suggest that administration of FXIII could be a reasonable and effective treatment for patients with pancreatic or/and enterocutaneous fistula who are resistant to standard treatments.

  19. Inflammatory Duodenal Polyposis Associated with Primary Immunodeficiency Disease: A Novel Case Report

    Science.gov (United States)

    Shera, Irfan Ali; Khurshid, Sheikh Mudassir

    2017-01-01

    Agammaglobulinemia is a rare form of B-cell primary immunodeficiency disease characterized by reduced levels of IgG, IgA, or IgM and recurrent bacterial infections. Agammaglobulinemia is most commonly associated with diffuse nodular lymphoid hyperplasia. Duodenal polyps are a rare entity; however, due to wide use of esophagogastroduodenoscopy, incidental diagnosis of duodenal polyps appears to be increasing. Although inflammatory duodenal polyposis has been reported in the literature, its association with common variable immunodeficiency has not been reported till date to the best of our knowledge. We report a case of a 59-year-old male with chronic symptoms of agammaglobulinemia associated with inflammatory duodenal polyposis. PMID:28163721

  20. Effect of cysteamine on cytosolic somatostatin binding sites in rabbit duodenal mucosa.

    Science.gov (United States)

    Gonzalez-Guijarro, L; Lopez-Ruiz, M P; Bodegas, G; Prieto, J C; Arilla, E

    1987-04-01

    Administration of cysteamine in rabbits elicited a rapid depletion of both duodenal mucosa and plasma somatostatin. A significant reduction was observed within 5 min, returning toward control values by 150 min. The depletion of somatostatin was associated with an increase in the binding capacity and a decrease in the affinity of both high- and low-affinity binding sites present in cytosol of duodenal mucosa. Incubation of cytosolic fraction from control rabbits with 1 mM cysteamine did not modify somatostatin binding. Furthermore, addition of cysteamine at the time of binding assay did not affect the integrity of 125I-Tyr11-somatostatin. It is concluded that in vivo administration of cysteamine to rabbits depletes both duodenal mucosa and plasma somatostatin and leads to up-regulation of duodenal somatostatin binding sites.

  1. Effects of Ginkgo biloba extract on cytoprotective factors in rats with duodenal ulcer

    Institute of Scientific and Technical Information of China (English)

    Jane C.-J. Chao; Huei-Chen Hung; Sheng-Hsuan Chen; Chia-Lang Fang

    2004-01-01

    AIM: To investigate the effects of Ginkgo biloba extract on cytoprotective factors in rats with duodenal ulcer.METHODS: Sprague-Dawley rats were randomly divided into four groups: sham operation without ginkgo, sham operation with ginkgo, duodenal ulcer without ginkgo, and duodenal ulcer with ginkgo. Rats with duodenal ulcer were induced by 500 mL/L acetic acid. Rats with ginkgo were intravenously injected with Ginkgo biloba extract from the tail at a dose of 0.5 mg/(kg.d) for 7 and 14 days.RESULTS: Pathological result showed that duodenal ulcer rats with ginkgo improved mucosal healing and inflammation compared with those without ginkgo after 7 d treatment. After 14 d treatment, duodenal ulcer rats with ginkgo significantly increased weight gain (34.0±4.5 g versus 24.5±9.5 g,P<0.05) compared with those without ginkgo. Duodenal ulcer rats significantly increased cell proliferation (27.4l±4.0and 27.8±2.3 BrdU-labeled cells in duodenal ulcer rats with and without ginkgo versus 22.4±3.5 and 20.8±0.5 BrdUlabeled cells in sham operation rats with and without ginkgo,P<0.05) compared with sham operation rats. Mucosal prostaglandin E2 concentration significantly increased by 129% (P<0.05) in duodenal ulcer rats with ginkgo compared with that in those without ginkgo. Duodenal ulcer rats without ginkgo significantly decreased superoxide dismutase activity in the duodenal mucosa and erythrocytes (19.4±6.7 U/mg protein versus 38.1±18.9 U/mg protein in the duodenal mucosa,and 4.87±1.49 U/mg protein versus 7.78±2.16 U/mg protein in erythrocytes, P<0.05) compared with sham operation rats without ginkgo. However, duodenal ulcer rats with ginkgo significantly increased erythrocyte superoxide dismutase activity (8.22±1.92 U/mg protein versus 4.87±1.49 U/mg protein,P<0.05) compared with those without ginkgo. Duodenal ulcer rats without ginkgo significantly increased plasma lipid peroxides (4.18±1. 12 μmol/mL versus 1.60±1.10 μmol/mL and 1.80±0.73

  2. Endoscopic Injection of a Ruptured Duodenal Varix with N-butyl-2-cyanoacrylate

    Directory of Open Access Journals (Sweden)

    Paulo Salgueiro

    2014-04-01

    Conclusions: The presented case supports endoscopic injection sclerotherapy with N-butyl-2-cyanoacrylate as a treatment option for ruptured duodenal varices that, despite being a rare event, when it occurs, is often fatal.

  3. Inflammatory Duodenal Polyposis Associated with Primary Immunodeficiency Disease: A Novel Case Report

    Directory of Open Access Journals (Sweden)

    Irfan Ali Shera

    2017-01-01

    Full Text Available Agammaglobulinemia is a rare form of B-cell primary immunodeficiency disease characterized by reduced levels of IgG, IgA, or IgM and recurrent bacterial infections. Agammaglobulinemia is most commonly associated with diffuse nodular lymphoid hyperplasia. Duodenal polyps are a rare entity; however, due to wide use of esophagogastroduodenoscopy, incidental diagnosis of duodenal polyps appears to be increasing. Although inflammatory duodenal polyposis has been reported in the literature, its association with common variable immunodeficiency has not been reported till date to the best of our knowledge. We report a case of a 59-year-old male with chronic symptoms of agammaglobulinemia associated with inflammatory duodenal polyposis.

  4. Duodenal Villous Atrophy in a TTG-Negative Patient Taking Olmesartan: A Case Report and Review of the Literature

    Directory of Open Access Journals (Sweden)

    Tasha Kulai

    2016-01-01

    Full Text Available Olmesartan, an angiotensin II receptor antagonist used to treat hypertension, is associated with few adverse effects. Here, a case of severe sprue-like enteropathy and acute kidney injury is described in a 68-year-old male taking olmesartan for 3-4 years. He presented to hospital with a five-week history of diarrhea, vomiting, and a 20 lb weight loss. Anti-TTG was negative with a normal IgA. Biopsies of the distal duodenum and duodenal cap revealed marked blunting of the villi with near complete villous atrophy of the biopsies from the bulb. There was an increase in intraepithelial lymphocytes as well as neutrophils in the surface epithelium. The patient’s diarrhea improved upon discontinuation of olmesartan and he returned to his previous weight. Repeat endoscopy four months later demonstrated complete resolution of inflammatory change with normal villous architecture. Long-term olmesartan use is associated with severe sprue-like enteropathy. The mechanism of intestinal injury is unknown. Duodenal biopsy results may mimic other enteropathies such as celiac disease. Physicians should consider medications as potential etiologies of enteropathy.

  5. Perforated duodenal ulcer a rare cause of acute abdomen in infancy: A report of two cases

    Directory of Open Access Journals (Sweden)

    Kadian Yogender

    2008-01-01

    Full Text Available Duodenal ulcer perforation is very uncommon in infants and children, that is why it is not usually considered in the differential diagnosis of acute abdomen in this age group. Moreover, the diagnosis of this condition is usually overlooked because of vague and variable symptoms and low index of suspicion on the part of the treating physicians. In this brief report, we are reporting two cases of successfully managed perforated duodenal ulcer in infancy.

  6. Gastric Duplication Cyst in Association with Duodenal Atresia in a Neonate

    Science.gov (United States)

    Mirshemirani, Alireza; Roshanzamir, Fatollah; Razavi, Sajad; Sarafi, Mehdi

    2016-01-01

    Concurrence of duodenal atresia and gastric duplication cyst is extremely rare entity. We report a 6-day-old female neonate who presented with neonatal intestinal obstruction. X-ray abdomen showed double bubble sign. At laparotomy, a huge cystic structure attached to greater curvature of the stomach along with duodenal atresia of second part of duodenum was found. The cystic structure was excised and duodeno-duodenostomy performed. Histopathology report confirmed it gastric duplication cyst. PMID:26816679

  7. Helicobacter pylori: the primary cause of duodenal ulceration or a secondary infection?

    Institute of Scientific and Technical Information of China (English)

    M Hobsley; Fl Tovey

    2001-01-01

    @@INTRODUCTION It is generally accepted that Helicobacter pylori ( H.pylori) infection has a role in duodenal ulceration .Eradicaton of H .pylori accelerates healing compared with placebo in the absence of control of gastric secretion and reduces ulcer recurrence .There is increasing evidence ,however ,that is may not be the primary cause of duodenal ulceration ,but that is may be a secondary factor in a nnmber of cases .This possibility is supported by four sets of observations : 1 Geographical distribution:

  8. Helicobacter pylori virulence factors in duodenal ulceration: A primary cause or a secondary infection causing chronicity

    Institute of Scientific and Technical Information of China (English)

    Frank I Tovey; Michael Hobsley; John Holton

    2006-01-01

    Reports from countries with a high prevalence of Helicobacter pylori (H pylori) infection do not show a proportionately high prevalence of duodenal ulceration,suggesting the possibility that H pylori cannot be a primary cause of duodenal ulceration. It has been mooted that this discrepancy might be explained by variations in the prevalence of virulence factors in different populations. The aim of this paper is to determine whether the published literature gives support to this possibility. The relevant literature was reviewed and analyzed separately for countries with a high and low prevalence of H pylori infection and virulence factors. Although virulent strains of H pylori were significantly more often present in patients with duodenal ulcer than without the disease in countries with a low prevalence of H pyloriinfection in the population, there was no difference in the prevalence of virulence factors between duodenal ulcer, non- ulcer dyspepsia or normal subjects in many countries, where the prevalence of both H pylori infection and of virulence factors was high.In these countries, the presence of virulence factors was not predictive the clinical outcome. To explain the association between virulence factors and duodenal ulcer in countries where H pylori prevalence is low,only two papers were found that give little support to the usual model proposed, namely that organisms with the virulence factors are more likely than those without them to initiate a duodenal ulcer. We offer an alternative hypothesis that suggests virulence factors are more likely to interfere with the healing of a previously produced ulcer. The presence of virulence factors only correlates with the prevalence of duodenal ulcer in countries where the prevalence of H pylori is low. There is very little evidence that virulence factors initiate duodenal ulceration, but they may be related to failure of the ulcer to heal.

  9. Dopamine enhances duodenal epithelial permeability via the dopamine D5 receptor in rodent.

    Science.gov (United States)

    Feng, X-Y; Zhang, D-N; Wang, Y-A; Fan, R-F; Hong, F; Zhang, Y; Li, Y; Zhu, J-X

    2017-05-01

    The intestinal barrier is made up of epithelial cells and intercellular junctional complexes to regulate epithelial ion transport and permeability. Dopamine (DA) is able to promote duodenal epithelial ion transport through D1-like receptors, which includes subtypes of D1 (D1 R) and D5 (D5 R), but whether D1-like receptors influence the duodenal permeability is unclear. FITC-dextran permeability, short-circuit current (ISC ), Western blot, immunohistochemistry and ELISA were used in human D5 R transgenic mice and hyperendogenous enteric DA (HEnD) rats in this study. Dopamine induced a downward deflection in ISC and an increase in FITC-dextran permeability of control rat duodenum, which were inhibited by the D1-like receptor antagonist, SCH-23390. However, DA decreased duodenal transepithelial resistance (TER), an effect also reversed by SCH-23390. A strong immunofluorescence signal for D5 R, but not D1 R, was observed in the duodenum of control rat. In human D5 R knock-in transgenic mice, duodenal mucosa displayed an increased basal ISC with high FITC-dextran permeability and decreased TER with a lowered expression of tight junction proteins, suggesting attenuated duodenal barrier function in these transgenic mice. D5 R knock-down transgenic mice manifested a decreased basal ISC with lowered FITC-dextran permeability. Moreover, an increased FITC-dextran permeability combined with decreased TER and tight junction protein expression in duodenal mucosa were also observed in HEnD rats. This study demonstrates, for the first time, that DA enhances duodenal permeability of control rat via D5 R, which provides new experimental and theoretical evidence for the influence of DA on duodenal epithelial barrier function. © 2016 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

  10. Duodenal ileus caused by a calf feeding nipple in a cow

    OpenAIRE

    2011-01-01

    Abstract Background The aim of this report was to describe duodenal obstruction caused by a rubber foreign body in a cow. Case Presentation The clinical, biochemical and ultrasonographic findings in a five-year-old Swiss Braunvieh cow with duodenal ileus caused by a calf feeding nipple are described. The main clinical signs were anorexia, ruminal tympany, decreased faecal output and abomasal reflux syndrome. Ultrasonographic examination revealed reticular hyperactivity and a dilated duodenum....

  11. Characterisation and Modelling of the Non Linear Mechanical Behaviour of Sepcarb NB41 Carbon/Carbon Composite

    Energy Technology Data Exchange (ETDEWEB)

    Abbe, F. [Snecma Prop Solide SAFRAN Grp, F-33187 Le Haillan (France); Herb, V.; Camus, G.; Martin, E. [Univ Bordeaux 1, Lab Composites Thermostruct, CNRS SPS CEA UB1, F-33600 Pessac (France)

    2009-08-15

    Design and optimization of a plasma facing component calls for dedicated constitutive laws which can handle the non linear behaviour typical of composite materials when applying this class of materials. This paper depicts the different phases of characterization and modelling which are required. Compared to a classical elastic analysis, this approach provides a more realistic estimate of the stress distribution within a thermally loaded PFC as demonstrated by finite element computations performed on a plasma facing component with a macro-bloc (R) geometry. (authors)

  12. Behavioural consequences of p-glycoprotein deficiency in mice, with special focus on stress-related mechanisms.

    Science.gov (United States)

    Schoenfelder, Y; Hiemke, C; Schmitt, U

    2012-05-01

    P-glycoprotein (P-gp), an efflux transporter localised in the blood-brain barrier, limits the access of multiple xenobiotics to the central nervous system. Whether it is also implemented in the transport of the endogenous glucocorticoid corticosterone is a matter of debate. The P-gp knockout mouse model [abcb1a/b (-/-)] has been shown to differ in the functioning of the hypothalamic-pituitary adrenal (HPA) axis. In the present study, we investigated the behaviour of abcb1a/b (-/-) and wild-type mice with respect to stress-related tests and the effects of corticosterone. Behavioural activities were assessed in the open field (OF) test for 4 days, and in the forced swimming test (FST) and tail suspension test (TST) under naïve and stressed conditions. The FST was also conducted after exogenous corticosterone injection (0.25 and 2.5 mg/kg). Moreover, the elevated plus maze test and the RotaRod test (RotaRod Advanced; TSE Systems, Bad Homburg, Germany) were assessed. Brain corticosterone levels were determined by an immunoassay and expression of glucocorticoid receptors by western blot analysis. Abcb1a/1b (-/-) mice showed significantly decreased brain corticosterone levels and elevated glucocorticoid receptor expression. Behavioural analysis revealed a significantly decreased activity in the OF test on the first 2 days in abcb1a/1b (-/-) mice compared to wild-type mice, although the differences disappeared under habituation. Immobility time in the FST was significantly decreased in abcb1a/1b (-/-) mice under basal and under stressed conditions, whereas immobility in the TST was significantly elevated in these mice under all conditions. Injection of exogenous corticosterone resulted in significant reductions of immobility in the FST in abcb1a/1b (-/-) mice, whereas wild-type mice did not respond to the same doses. There were no differences in the elevated plus maze test and RotaRod test. The results obtained in the present study demonstrate that a P-gp deficiency has

  13. Influence of isothermal ageing on mechanical behaviour in Ni-rich Ti-Zr-Ni shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sandu, A.M. [Department of Production Systems Engineering, Toyohashi University of Technology, Tempaku-cho, Hibarigaoka 1-1, Toyohashi, Aichi 441-8580 (Japan)]. E-mail: adrian@martens.pse.tut.ac.jp; Tsuchiya, K. [Department of Production Systems Engineering, Toyohashi University of Technology, Tempaku-cho, Hibarigaoka 1-1, Toyohashi, Aichi 441-8580 (Japan); Yamamoto, S. [Department of Production Systems Engineering, Toyohashi University of Technology, Tempaku-cho, Hibarigaoka 1-1, Toyohashi, Aichi 441-8580 (Japan); Todaka, Y. [Department of Production Systems Engineering, Toyohashi University of Technology, Tempaku-cho, Hibarigaoka 1-1, Toyohashi, Aichi 441-8580 (Japan); Umemoto, M. [Department of Production Systems Engineering, Toyohashi University of Technology, Tempaku-cho, Hibarigaoka 1-1, Toyohashi, Aichi 441-8580 (Japan)

    2006-12-15

    effect of isothermal ageing on compression cycling, martensitic transformation temperatures and microstructure was investigated for a Ti-6 mol.%Zr-53 mol.%Ni alloy. The ageing behaviour of the microstructures was a two-stage process, i.e., an enhancement of diffuse scattering in electron diffraction pattern, most likely related to development of short-range order (SRO) structure, and then fine coherent precipitation followed by coarsening. Microstructures with fine coherent precipitates or well-developed SRO offer the best superelastic properties.

  14. Divertículo duodenal perforado como causa de abdomen agudo quirúrgico Perforated duodenal diverticulum as cause of surgical acute abdomen

    Directory of Open Access Journals (Sweden)

    Nizahel Estévez Álvarez

    2011-12-01

    Full Text Available La enfermedad diverticular duodenal es considerada en el ámbito de la cirugía de vías digestivas como inusual. Por su parte, la complicación menos frecuente referida en la literatura médica lo constituye la perforación aguda, y cuando esta ocurre siempre se practicará tratamiento quirúrgico de urgencia. Resulta polémico llegar a un consenso general que dirija la metodología diagnóstica, debido a su atípica forma de presentación. La tomografía abdominal ha resultado de gran utilidad en el diagnóstico de esta entidad. Se reportan tasas de mortalidad altas (25-30 % originadas, generalmente, por la dificultad diagnóstica frente a esta enfermedad. Se presenta un nuevo caso de divertículo duodenal perforado en una paciente, del sexo femenino, de 60 años de edad. La técnica quirúrgica empleada en esta oportunidad consistió en la exclusión duodenal y el drenaje del retroperitoneo.The duodenal diverticular disease is considered within surgery of digestive tracts as unusual. The less frequent complication referred in medical literature is the acute perforation and when it occurs always will be carried out the emergency surgical treatment. It is polemic to arrive to a general consensus directing the diagnostic methodology due to its atypical way of presentation. The abdominal tomography has been very useful in diagnosis of this entity. Authors report high mortality rates (25-30 % in general originated by the diagnostic difficulty in face of this disease. A new case of perforated duodenal diverticulum of a female sex patient aged 60. The surgical technique used in this opportunity was the duodenal exclusion and the retroperitoneal drainage.

  15. Duodenal Wedge Resection for Large Gastrointestinal Stromal Tumour Presenting with Life-Threatening Haemorrhage

    Directory of Open Access Journals (Sweden)

    Alexander Shaw

    2013-01-01

    Full Text Available Background. Duodenal gastrointestinal stromal tumours (GISTs are an uncommon malignancy of the gastrointestinal (GI tract. We present a case of life-threatening haemorrhage caused by a large ulcerating duodenal GIST arising from the third part of the duodenum managed by a limited duodenal wedge resection. Case Presentation. A 61-year-old patient presented with acute life-threatening gastrointestinal bleeding. After oesophagogastroduodenoscopy failed to demonstrate the source of bleeding, a 5 cm ulcerating exophytic mass originating from the third part of the duodenum was identified at laparotomy. A successful limited wedge resection of the tumour mass was performed. Histopathology subsequently confirmed a duodenal GIST. The patient remained well at 12-month followup with no evidence of local recurrence or metastatic spread. Conclusion. Duodenal GISTs can present with life-threatening upper GI haemorrhage. In the context of acute haemorrhage, even relatively large duodenal GISTs can be treated by limited wedge resection. This is a preferable alternative to duodenopancreatectomy with lower morbidity and mortality but comparable oncological outcome.

  16. A brief analysis of patients suffering from stomach or duodenal ulcers in Almaty hospital №1

    Directory of Open Access Journals (Sweden)

    Aryzbekova Aliya

    2015-12-01

    Full Text Available Peptic ulcers are a serious problem worldwide, and affect about 4 million people each year. Their etiology is connected with the presence of Helicobacter pylori, the act of smoking, drinking alcohol, being stress, and taking excessively nonsteroidal anti-inflammatory drugs, as well as steroids. The most common symptoms are abdominal pain, nausea, chest pain and fatigue, while less frequent symptoms include vomiting and weight loss. Helicobacter pylori is responsible for about 80% of gastric and 90% of duodenal ulcer cases. In this work, an analysis is made of a correlation between stomach or duodenal ulcer and gender, residence and number of patients hospitalized in the Almaty hospital №1, from 2009-2012, in order to learn about trends in the incidence of these diseases in Kazakhstan. A total number of 950 patients with stomach and duodenal ulcers, in 2009-2012, were questioned. The patient’s residence, gender and stomach or duodenal ulcer problem were taken into account in the study. The result of this work reveals that the largest amount of hospitalized patients suffering from stomach or duodenal ulcers came from urban areas. Moreover, more women than men suffered from peptic ulcers. Furthermore, the number of patients admitted to the hospital due to duodenal ulcers did not show any variation throughout the study. However, the least number of patients suffering from gastric ulcers was noticed in December 2009, and the greatest was in October and November 2011. The obtained data show that ulcers are a serious problem in Kazakhstan.

  17. Successful mucosal incision-assisted biopsy for the histological diagnosis of duodenal lymphoma: A case report

    Science.gov (United States)

    MORISHITA, ASAHIRO; MORI, HIROHITO; KOBARA, HIDEKI; NISHIYAMA, NORIKO; FUJIHARA, SHINTARO; YACHIDA, TATSUO; AYAKI, MAKI; MATSUNAGA, TAE; SAKAMOTO, TEPPEI; MAEDA, EMIKO; NOMURA, TAKAKO; TANI, JOJI; MIYOSHI, HISAAKI; YONEYAMA, HIROHITO; HIMOTO, TAKASHI; KAGAWA, SEIKO; HABA, REIJI; MASAKI, TSUTOMU

    2016-01-01

    Tissue sampling of primary duodenal lymphoma is essential for its histological diagnosis. Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA), which is frequently used for submucosal tumor (SMT)-like duodenal tumors, is adequate for cytological diagnosis, but not for histological diagnosis. Therefore, in the present study, a mucosal incision-assisted biopsy (MIAB) was performed in an 81-year-old woman for the diagnosis of an SMT-like duodenal mass, as tissue sampling for histological analysis using a regular endoscopic biopsy had failed to establish a definite diagnosis of malignant lymphoma. EUS-FNA had also led to poor tissue sampling due to the difficult location of the duodenal tumor. The pathological examination of biopsy samples using MIAB revealed the presence of a diffuse proliferation of atypical lymphocytes, and the expression of cluster of differentiation (CD)20 and CD79a, but no expression of CD3 in the tumor specimens. The patient was diagnosed with diffuse large B-cell lymphoma. To the best of knowledge, this is first report of a case using MIAB as a sampling method for the histological diagnosis of SMT-like primary duodenal lymphoma. This case suggests that MIAB may be an essential method for obtaining tissue samples from SMT-like duodenal tumors. PMID:26870243

  18. The atomic world spooky? It ain't necessarily so! emergent quantum mechanics, how the classical laws of nature can conspire to cause quantum-like behaviour

    CERN Document Server

    van Holten, Theo

    2017-01-01

    The present book takes the discovery that quantum-like behaviour is not solely reserved to atomic particles one step further. If electrons are modelled as vibrating droplets instead of the usually assumed point objects, and if the classical laws of nature are applied, then exactly the same behaviour as in quantum theory is found, quantitatively correct! The world of atoms is strange and quantum mechanics, the theory of this world, is almost magic. Or is it? Tiny droplets of oil bouncing round on a fluid surface can also mimic the world of quantum mechanics. For the layman - for whom the main part of this book is written - this is good news. If the everyday laws of nature can conspire to show up quantum-like phenomena, there is hope to form mental pictures how the atomic world works. The book is almost formula-free, and explains everything by using many sketches and diagrams. The mathematical derivations underlying the main text are kept separate in a -peer reviewed - appendix. The author, a retired professor ...

  19. Mechanical behaviour and functional properties of porous Ti-45 at. % Ni alloy produced by self-propagating high-temperature synthesis

    Science.gov (United States)

    Resnina, N.; Belyaev, S.; Voronkov, A.; Gracheva, A.

    2016-05-01

    The mechanical behaviour and shape memory effects were studied in the porous Ti-45.0 at. % Ni alloy produced by self-propagating high-temperature synthesis. It is shown that the porous Ti-45.0 at % Ni alloy is deformed by the same mechanisms as a cast Ti50Ni50 alloy. At low temperatures, the deformation of the porous alloy is realised via martensite reorientation at a low yield limit and by dislocation slip at a high yield limit. At high temperatures (in the austenite B2 phase) the porous Ti-45.0 at % Ni alloy is deformed by the stress-induced martensite at a low yield limit and by dislocation slip at a high yield limit. The pseudoelasticity effect is not found in this alloy, while the transformation plasticity and the shape memory effects are observed on cooling and heating under a constant load. The values of the transformation plasticity, and the shape memory effects, depend linearly on the stress acting on cooling and heating. The temperatures of the martensitic transformation increase linearly when the stress rises up to 80 MPa. The porous Ti-45.0 at % Ni alloy accumulates an irreversible strain on cooling and heating and demonstrates unstable functional behaviour during thermal cycling.

  20. Duodenal stenting for malignant gastric outlet obstruction:Prospective study

    Institute of Scientific and Technical Information of China (English)

    Eduardo Guimar(a)es Hourneaux Moura; Flávio Coelho Ferreira; Spencer Cheng; Diogo Turiani Hourneaux Moura; Paulo Sakai; Bruno Zilberstain

    2012-01-01

    AIM:To evaluate the results of duodenal stenting for palliation of gastroduodenal malignant obstruction by using a gastric outlet obstruction score (GOOS).METHODS:A prospective,non-randomized study was performed at a tertiary center between August 2005 and April 2010.Patients were eligible if they had malignant gastric outlet obstruction (GOO) and were not candidates for surgical treatment.Medical history and patient demographics were collected at baseline.Scheduled interviews were made on the day of the procedure and 15,30,90 and 180 d later or unscheduled as necessary.RESULTS:Fifteen patients (6 male,9 female; median age 61 years) with GOO who had undergone duodenal stenting were evaluated.Ten patients had metastasis at baseline (66.6%) and 14 were unable to accept oral intake (93.33%),including 7 patients who were using a feeding tube.Laboratory data showed biliary obstruction in eight cases (53.33%); all were submitted to biliary drainage.Two patients developed obstructive symptoms due to tumor ingrowth after 30 d and another due to tumor overgrowth after 180 d.Two cases of stent migration occurred.A good response to treatment was observed,with a mean time of approximately 1 d (19 h) until toleration of a liquid diet and slightly more than 2 d for both soft solids (51 h) and a solid food/normal diet (55 h).The mean time to first failure to maintain liquid intake (GOOS ≥ 1) was 93 d.During follow-up,the mean time to first failure to maintain the previously achieved GOOS of 2-3 (solid/semi-solid food),considered technical failure,was 71 d.On the basis of oral intake a GOOS is defined:0 for no oral intake; 1 for liquids only; 2 for soft solids only; 3 for lowresidue or full diet.CONCLUSION:Enteral stenting to alleviate gastroduodenal malignant obstruction improves quality of life in patients with limited life expectancy,which can be evaluated by using a GOO scoring system.