WorldWideScience

Sample records for sustain mechanical stress

  1. Mechanical integrity and sustainability of pre-stressed concrete bridge girders repaired by epoxy injection – phase 1.

    Science.gov (United States)

    2017-02-02

    At present, there is a need to assess the mechanical integrity and sustainability of pre-stressed concrete beams during the entire life cycle of the built infrastructure. According to the NCHRP (Tadros et al., 2010), further research to develop fi...

  2. Numerical investigation on effect of leaflet thickness on structural stresses developed in a bileaflet mechanical heart valve for its sustainable manufacturing

    Directory of Open Access Journals (Sweden)

    Abbas Syed Samar

    2017-01-01

    Full Text Available Flow induced structural stresses can cause mechanical prosthetic aortic valve to fail due to yielding. In this study, we have performed the structural analysis, especially the effect of leaflet thickness on equivalent stresses developed in a Bileaflet mechanical heart valve (BMHV due to blood flow through it has been investigated. The leaflet thickness varies from 0.5mm to 0.7mm, by 0.1mm. A fluid-structure interaction approach based on Arbitrary Lagrangian Eulerian (ALE technique has been employed with the aid of an user defined function (UDF. Results of the analysis show that high von Mises stresses are developed in BMHV with leaflet thickness of 0.5mm and 0.6mm, being 75% and 13% higher than allowable equivalent stress respectively. Such thinner leaflets are therefore, not sustainable to be replaced with diseased aortic valve.

  3. Molecular mechanisms in plant abiotic stress response

    Directory of Open Access Journals (Sweden)

    Poltronieri Palmiro

    2011-01-01

    Full Text Available Improved crop varieties are needed to sustain the food supply, to fight climate changes, water scarcity, temperature increase and a high variability of rainfalls. Variability of drought and increase in soil salinity have negative effects on plant growth and abiotic stresses seriously threaten sustainable agricultural production. To overcome the influence of abiotic stresses, new tolerant plant varieties and breeding techniques using assisted selection are sought. A deep understanding of the mechanisms that respond to stress and sustain stress resistance is required. Here is presented an overview of several mechanisms that interact in the stress response. Localised synthesis of plant hormones, second messengers and local effectors of abiotic stress response and survival, the signaling pathways regulated by plant hormones are today better understood. Metabolic networks in drought stress responses, long distance signaling, cross-talk between plant organs finalised to tissue-specific expression of abiotic stress relieving genes have been at the centre of most recent studies.

  4. Mechanical Stresses in Carotid Plaques

    DEFF Research Database (Denmark)

    Samuel, Samuel Alberg

    simulationer, som tillod beregning af longitudinelle stress-niveauer i den fibrøse kappe. Afhandlingen indeholder tre artikler, som beskriver denne metode. Den første; “Mechanical Stresses in Carotid Plaques using MRI-Based Fluid Structure Interaction Models”, beskriver i detaljer metoden til at danne de...

  5. Study on Clean Development Mechanism, Quantitative and Sustainable Mechanism

    Directory of Open Access Journals (Sweden)

    Donghai Yuan

    2015-01-01

    Full Text Available Aiming at the system and market problem of clean development mechanism (CDM, this study is carried out to establish the feasibility of certified emission reduction (CER quantitative evaluation method and reserve mechanism in host country at the United Nations Framework Convention on Climate Change (UNFCCC level. After the introduction of CER quantitative and sustainable mechanism, the amount of CER that can enter the market was cut to a quarter, which reduces about 75% of the expected CER supply. Market CER from the technology types of higher CER market share and lower support for sustainable development appears to have different degrees of reduction. As for the technology types of lower CER market share and higher support for sustainable development, the amount of market CER is maintained in line with prevailing scenario, and market CER supply becomes more balanced.

  6. Stress coping mechanisms in smoking psoriatics

    Directory of Open Access Journals (Sweden)

    Ilknur Altunay

    2013-09-01

    Conclusion: Smoking and nonsmoking psoriatic patients had similar stress coping strategies, except the subgroup seeking social support, and usually used positive ways of coping with stress. Psoriatic patients who smoke might employ smoking to avoid stressful situations. They would benefit from education on adopting healthy stress management and, in turn, developing mature stress coping mechanisms. Future prospective studies are required to address the exact causal link between smoking, psoriasis and psychiatric comorbidity, including stress coping mechanisms.

  7. Stress-Induced Neurodegeneration: Mechanisms and Interventions

    National Research Council Canada - National Science Library

    Meyerhoff, James

    2000-01-01

    ...) memory function has been localized to the hippocampus. Humans exposed to extreme stress for sustained periods have suffered deterioration of memory and inability to concentrate, as well as CNS atrophy...

  8. Molecular mechanisms in plant abiotic stress response

    OpenAIRE

    Poltronieri Palmiro; Bonsegna Stefania; De Domenico Stefania; Santino Angelo

    2011-01-01

    Improved crop varieties are needed to sustain the food supply, to fight climate changes, water scarcity, temperature increase and a high variability of rainfalls. Variability of drought and increase in soil salinity have negative effects on plant growth and abiotic stresses seriously threaten sustainable agricultural production. To overcome the influence of abiotic stresses, new tolerant plant varieties and breeding techniques using assisted selection are sought. A deep understanding of the m...

  9. "Omics" of maize stress response for sustainable food production: opportunities and challenges.

    Science.gov (United States)

    Gong, Fangping; Yang, Le; Tai, Fuju; Hu, Xiuli; Wang, Wei

    2014-12-01

    Maize originated in the highlands of Mexico approximately 8700 years ago and is one of the most commonly grown cereal crops worldwide, followed by wheat and rice. Abiotic stresses (primarily drought, salinity, and high and low temperatures), together with biotic stresses (primarily fungi, viruses, and pests), negatively affect maize growth, development, and eventually production. To understand the response of maize to abiotic and biotic stresses and its mechanism of stress tolerance, high-throughput omics approaches have been used in maize stress studies. Integrated omics approaches are crucial for dissecting the temporal and spatial system-level changes that occur in maize under various stresses. In this comprehensive analysis, we review the primary types of stresses that threaten sustainable maize production; underscore the recent advances in maize stress omics, especially proteomics; and discuss the opportunities, challenges, and future directions of maize stress omics, with a view to sustainable food production. The knowledge gained from studying maize stress omics is instrumental for improving maize to cope with various stresses and to meet the food demands of the exponentially growing global population. Omics systems science offers actionable potential solutions for sustainable food production, and we present maize as a notable case study.

  10. Controlling stress corrosion cracking in mechanism components of ground support equipment

    Science.gov (United States)

    Majid, W. A.

    1988-01-01

    The selection of materials for mechanism components used in ground support equipment so that failures resulting from stress corrosion cracking will be prevented is described. A general criteria to be used in designing for resistance to stress corrosion cracking is also provided. Stress corrosion can be defined as combined action of sustained tensile stress and corrosion to cause premature failure of materials. Various aluminum, steels, nickel, titanium and copper alloys, and tempers and corrosive environment are evaluated for stress corrosion cracking.

  11. Focal adhesions, stress fibers and mechanical tension

    Energy Technology Data Exchange (ETDEWEB)

    Burridge, Keith, E-mail: Keith_Burridge@med.unc.edu [Department of Cell Biology and Physiology, and Lineberger Comprehensive Cancer Center, 12-016 Lineberger, CB#7295, University of North Carolina, Chapel Hill, NC (United States); Guilluy, Christophe, E-mail: christophe.guilluy@univ-nantes.fr [Inserm UMR-S1087, CNRS UMR-C6291, L' institut du Thorax, and Université de Nantes, Nantes (France)

    2016-04-10

    Stress fibers and focal adhesions are complex protein arrays that produce, transmit and sense mechanical tension. Evidence accumulated over many years led to the conclusion that mechanical tension generated within stress fibers contributes to the assembly of both stress fibers themselves and their associated focal adhesions. However, several lines of evidence have recently been presented against this model. Here we discuss the evidence for and against the role of mechanical tension in driving the assembly of these structures. We also consider how their assembly is influenced by the rigidity of the substratum to which cells are adhering. Finally, we discuss the recently identified connections between stress fibers and the nucleus, and the roles that these may play, both in cell migration and regulating nuclear function. - Highlights: • The different types of stress fiber and focal adhesion are described. • We discuss the controversy about tension and assembly of these structures. • We describe the different models used to investigate assembly of these structures. • The influence of substratum rigidity is discussed. • Stress fiber connections to the nucleus are reviewed.

  12. Stress controls the mechanics of collagen networks

    Science.gov (United States)

    Licup, Albert James; Münster, Stefan; Sharma, Abhinav; Sheinman, Michael; Jawerth, Louise M.; Fabry, Ben; Weitz, David A.; MacKintosh, Fred C.

    2015-01-01

    Collagen is the main structural and load-bearing element of various connective tissues, where it forms the extracellular matrix that supports cells. It has long been known that collagenous tissues exhibit a highly nonlinear stress–strain relationship, although the origins of this nonlinearity remain unknown. Here, we show that the nonlinear stiffening of reconstituted type I collagen networks is controlled by the applied stress and that the network stiffness becomes surprisingly insensitive to network concentration. We demonstrate how a simple model for networks of elastic fibers can quantitatively account for the mechanics of reconstituted collagen networks. Our model points to the important role of normal stresses in determining the nonlinear shear elastic response, which can explain the approximate exponential relationship between stress and strain reported for collagenous tissues. This further suggests principles for the design of synthetic fiber networks with collagen-like properties, as well as a mechanism for the control of the mechanics of such networks. PMID:26195769

  13. Worldwide Research on Plant Defense against Biotic Stresses as Improvement for Sustainable Agriculture

    Directory of Open Access Journals (Sweden)

    Estela Gimenez

    2018-02-01

    Full Text Available Agriculture is the basis for food production on a global scale. Sustainable agriculture tries to improve or maintain the quality of food without compromising the environment. As sessile organisms, plants cannot avoid adverse environmental conditions and contact with other living organisms. The damage caused to plants by other living organisms such as parasites and pathogens (virus, bacteria, fungi, nematodes or insects brings about what is known as biotic stress. Plants are constantly exposed to biotic stress, which causes changes in plant metabolism involving physiological damages that lead to a reduction of their productivity. To fight biotic stress, plants have developed sophisticated defense mechanisms. Thus, understanding plant defense mechanisms might prevent important crop and economic losses. In this article, a bibliometric analysis of biotic stress is carried out. Different aspects of the publications are analyzed, such as publication type, research field, journal type, countries and their institutions, as well as the keyword occurrence frequency, and finally special attention is paid to the plant studied by the leading countries and institutions. As expected, journals selected by authors to publish their relevant findings are plant-specific journals. However, it should be noted that the fourth position, in terms of the number of publications per journal, is occupied by BMC Genomics journal. Such a journal considers mainly articles on genomics, which indicates the involvement of genetic factors in the control of biotic stress. Analysis of the keywords used in publications about biotic stress shows the great interest in the biotic–abiotic stress interaction, in the gene expression regulation in plants as well as phytohormones in the current research. In short, the great effort made by the scientific community in the biotic and abiotic stresses field with the aim to understand, regulate and control plant damages caused by biotic stress

  14. Endoplasmic Reticulum Stress and Apoptosis Mechanisms

    Directory of Open Access Journals (Sweden)

    G.Seyda Seydel

    2012-08-01

    Full Text Available Thhe endoplasmic reticulum (ER is the principal site for the synthesis, folding and maturation of most secreted proteins in the cell and essential for most cellular activities. Conditions that impair the folding capacity of the ER cause ER stress and induce a set of signaling pathways termed the unfolded protein response (UPR. If the protective mechanism activated by the UPR is not sufficient to restore normal ER function, cells die by apoptosis mechanism. Recent research suggests that ER stress and UPR play important roles in the metabolic disorders such as diabetes and obesity, cancer, immune response and in some neurodegenerative diseases such as Alzheimer, Parkinson, Huntington. Further studies on ER stress and UPR are necessary to clarify the exact role of this physiological mechanism and provide novel avenues to potential therapies. This review will provide an overview of ER stress, the UPR signaling pathways and ER stress induced apoptosis mechanism. [Archives Medical Review Journal 2012; 21(4.000: 221-235

  15. Peripheral and central mechanisms of stress resilience

    Science.gov (United States)

    Pfau, Madeline L.; Russo, Scott J.

    2014-01-01

    Viable new treatments for depression and anxiety have been slow to emerge, likely owing to the complex and incompletely understood etiology of these disorders. A budding area of research with great therapeutic promise involves the study of resilience, the adaptive maintenance of normal physiology and behavior despite exposure to marked psychological stress. This phenomenon, documented in both humans and animal models, involves coordinated biological mechanisms in numerous bodily systems, both peripheral and central. In this review, we provide an overview of resilience mechanisms throughout the body, discussing current research in animal models investigating the roles of the neuroendocrine, immune, and central nervous systems in behavioral resilience to stress. PMID:25506605

  16. Peripheral and central mechanisms of stress resilience

    Directory of Open Access Journals (Sweden)

    Madeline L. Pfau

    2015-01-01

    Full Text Available Viable new treatments for depression and anxiety have been slow to emerge, likely owing to the complex and incompletely understood etiology of these disorders. A budding area of research with great therapeutic promise involves the study of resilience, the adaptive maintenance of normal physiology and behavior despite exposure to marked psychological stress. This phenomenon, documented in both humans and animal models, involves coordinated biological mechanisms in numerous bodily systems, both peripheral and central. In this review, we provide an overview of resilience mechanisms throughout the body, discussing current research in animal models investigating the roles of the neuroendocrine, immune, and central nervous systems in behavioral resilience to stress.

  17. Key Sustainable Tourism Mechanisms for Poverty Reduction and ...

    African Journals Online (AJOL)

    Increasing populations, together with the impact of climate change, are resulting in greater competition for land and a necessity for sustainable land use. Tourism can provide a flow of benefits from conservation to rural communities to reduce poverty and promote biodiversity conservation. Three key mechanisms of ...

  18. WP/072 Is the Clean Development Mechanism Promoting Sustainable Development?

    DEFF Research Database (Denmark)

    Huang, Yongfu; He, Jingjing; Tarp, Finn

    One of the dual objectives of the Clean Development Mechanism (CDM) of the Kyoto Protocol is to promote sustainable development in the host countries. With different CDM indicators for 58 CDM host countries over 2005-10, this paper empirically assesses whether CDM project development fulfils...

  19. Devolution: A mechanism for scaling adoption of sustainable land ...

    African Journals Online (AJOL)

    Sustainable Land Management (SLM) technologies are known to improve food production and productivity in areas prone to high soil degradation, arising from water and soil nutrient losses. In eastern Africa, mechanisms for mitigation of this land degradation have been developed, but their uptake has been minimal.

  20. Mechanics of couple-stress fluid coatings

    Science.gov (United States)

    Waxman, A. M.

    1982-01-01

    The formal development of a theory of viscoelastic surface fluids with bending resistance - their kinematics, dynamics, and rheology are discussed. It is relevant to the mechanics of fluid drops and jets coated by a thin layer of immiscible fluid with rather general rheology. This approach unifies the hydrodynamics of two-dimensional fluids with the mechanics of an elastic shell in the spirit of a Cosserat continuum. There are three distinct facets to the formulation of surface continuum mechanics. Outlined are the important ideas and results associated with each: the kinematics of evolving surface geometries, the conservation laws governing the mechanics of surface continua, and the rheological equations of state governing the surface stress and moment tensors.

  1. Involvement of Mechanical Stress in Androgenetic Alopecia

    Science.gov (United States)

    Tellez-Segura, Rafael

    2015-01-01

    Context: Androgenetic alopecia (AGA) is a frequent disorder characterized by progressive hair miniaturization in a very similar pattern among all affected men. The pathogenesis is related to androgen-inducible overexpression of transforming growth factor β-1 from balding dermal papilla cells, which is involved in epithelial inhibition and perifollicular fibrosis. Recent research shows that hair follicle androgen sensitivity is regulated by Hic-5, an androgen receptor co-activator which may be activated by the mechanical stimulation. Moreover, the dermis of scalp susceptible to be affected by AGA is firmly bounded to the galea aponeurotica, so the physical force exerted by the occipitofrontalis muscle is transmitted to the scalp skin. Aims: To know whether mechanical stress supported by hair follicles is involved in AGA phenomenon. Materials and Methods: It is performed with a finite element analysis of a galea model and a schematic representation of AGA progression according to Hamilton–Norwood scale in order to establish the correlation between elastic deformation in scalp and clinical progression of male pattern baldness. Results: The result was a highly significant correlation (r: −0.885, P < 0.001) that clearly identifies a mechanical factor in AGA development. Conclusions: All these data suggest that mechanical stress determines AGA patterning and a stretch-induced and androgen-mediated mechanotransduction in dermal papilla cells could be the primary mechanism in AGA pathogenesis. PMID:26622151

  2. Plant Responses to Salt Stress: Adaptive Mechanisms

    Directory of Open Access Journals (Sweden)

    Jose Ramón Acosta-Motos

    2017-02-01

    Full Text Available This review deals with the adaptive mechanisms that plants can implement to cope with the challenge of salt stress. Plants tolerant to NaCl implement a series of adaptations to acclimate to salinity, including morphological, physiological and biochemical changes. These changes include increases in the root/canopy ratio and in the chlorophyll content in addition to changes in the leaf anatomy that ultimately lead to preventing leaf ion toxicity, thus maintaining the water status in order to limit water loss and protect the photosynthesis process. Furthermore, we deal with the effect of salt stress on photosynthesis and chlorophyll fluorescence and some of the mechanisms thought to protect the photosynthetic machinery, including the xanthophyll cycle, photorespiration pathway, and water-water cycle. Finally, we also provide an updated discussion on salt-induced oxidative stress at the subcellular level and its effect on the antioxidant machinery in both salt-tolerant and salt-sensitive plants. The aim is to extend our understanding of how salinity may affect the physiological characteristics of plants.

  3. Cold stress tolerance mechanisms in plants. A review

    OpenAIRE

    Yadav, Sudesh Kumar

    2010-01-01

    International audience; The human population is increasing at an alarming rate, whereas at the same time agricultural productivity is decreasing due to the effect of various environmental problems. In particular, cold stress is a serious threat to the sustainability of crop yields. Indeed, cold stress can lead to major crop losses. Various phenotypic symptoms in response to cold stress include poor germination, stunted seedlings, yellowing of leaves (chlorosis), reduced leaf expansion and wil...

  4. Mechanical stress regulation of plant growth and development

    Science.gov (United States)

    Mitchell, C. A.; Myers, P. N.

    1995-01-01

    The authors introduce the chapter with a discussion of lessons from nature, agriculture, and landscapes; terms and definitions; and an historical perspective of mechanical stress regulation of plant growth and development. Topics include developmental responses to mechanical stress; mechanical stress-environment interactions; metabolic, productivity, and compositional changes; hormonal involvement; mechanoperception and early transduction mechanisms; applications in agriculture; and research implications. The discussion of hormonal involvement in mechanical stress physiology includes ethylene, auxin, gibberellins, and other phytohormones. The discussion of applications in agriculture examines windbreaks, nursery practices, height control and conditioning, and enhancement of growth and productivity. Implications for research are related to handling plant materials, space biology, and future research needs.

  5. A Reformed CDM - including new mechanisms for sustainable development

    Energy Technology Data Exchange (ETDEWEB)

    Holm Olsen, K.; Fenhann, J.

    2009-07-01

    The annual CD4CDM Perspectives Series features a topic of pivotal importance to the global carbon market. The series seeks to communicate the diverse insights and visions of leading actors in the carbon market to better inform the decisions of professionals and policymakers in developing countries. The second theme of the series focuses on how the CDM can be reformed in a post-2012 climate regime, including new mechanism for sustainable development. Seventeen contributors from the private sector, Designated National Authorities, the Executive Board, research, and development agencies present their perspective on meeting challenges such as the unequal regional distribution of CDM projects, concerns about environmental integrity and technology transfer, complex governance procedures, and questions about the CDM's contribution to sustainable development. The new ideas and solutions to these challenges proposed by the authors in this edition of Perspectives have been solicited to help professionals and policy makers make the best decisions in the lead-up to COP 15 in Copenhagen and beyond. (au)

  6. Mechanisms of Stress-induced Visceral Pain

    OpenAIRE

    Greenwood-Van Meerveld, Beverley; Johnson, Anthony C

    2018-01-01

    Evidence suggests that long-term stress facilitates visceral pain through sensitization of pain pathways and promotes chronic visceral pain disorders such as the irritable bowel syndrome (IBS). This review will describe the importance of stress in exacerbating IBS-induced abdominal pain. Additionally, we will briefly review our understanding of the activation of the hypothalamic-pituitary-adrenal axis by both chronic adult stress and following early life stress in the pathogenesis of IBS. The...

  7. Learning to cope with stress: psychobiological mechanisms of stress resilience.

    Science.gov (United States)

    Cabib, Simona; Campus, Paolo; Colelli, Valentina

    2012-01-01

    Stress is the main non-genetic source of psychopathology. Therefore, the identification of neurobiological bases of resilience, the resistance to pathological outcomes of stress, is a most relevant topic of research. It is an accepted view that resilient individuals are those who do not develop helplessness, or other depression-like phenotypes, following a history of stress. In the present review, we discuss the phenotypic differences between mice of the inbred C57BL/6J and DBA/2J strains that could be associated with the strain-specific resistance to helplessness observable in DBA/2J mice. The reviewed results support the hypothesis that resilience to stress-promoted helplessness develops through interactions between a specific genetic makeup and a history of stress, and is associated with an active coping style, a bias toward the use of stimulus-response learning, and specific adaptive changes of mesoaccumbens dopamine transmission under stress. Finally, evidence that compulsivity represents a side effect of the neuroadaptive processes fostering resistance to develop depressive-like phenotypes under stress is discussed.

  8. Computational modeling of the mechanical modulation of the growth plate by sustained loading

    Directory of Open Access Journals (Sweden)

    Narváez-Tovar Carlos A

    2012-09-01

    Full Text Available Abstract This paper presents a computational model that describes the growth of the bone as a function of the proliferation and hypertrophy of chondrocytes in the growth plate. We have included the effects of the mechanical loads on the sizes of the proliferative and hypertrophic areas, the number of proliferative chondrocytes and the final size of the hypertrophic chondrocytes. The validation of the model was performed with experimental data published on other investigations about proximal tibia of rats, subjected to sustained axial stresses of 0.1 MPa, 0.0 MPa, -0.1 MPa and −0.2 MPa. Growth was simulated during 23 days, obtaining numerical errors between 2.77% and 3.73% with respect to experimental growth rates. The results obtained show that the model adequately simulates the behavior of the growth plate and the effect of mechanical loads over its cellular activity.

  9. EFL Foreign Teacher Stress in Korea: Causes and Coping Mechanisms

    Science.gov (United States)

    Brundage, Gregory C.

    2007-01-01

    Survey study of 53 foreign EFL teachers in Jeonju City, South Korea looks at causes of teacher stress and coping mechanisms between the years of 2004 and 2006. Results show foreign EFL teachers report moderate levels of stress and attribute stresses in roughly equal measures to student misbehavior and school director/administrative sources. Survey…

  10. induction of oxidative stress and antioxidative mechanisms

    African Journals Online (AJOL)

    Prof. Adipala Ekwamu

    calculatedfrom the extinction coefficient of 155. mM-1 cm-1. Polyamines were detected ..... stress exhibited marginal elevation in PRO levels as a function of time (Table 1). It has been reported that metal stress results in water deficit, which in turn, causes PRO accumulation (Sharma et al., 1998), thus contributing to osmotic.

  11. Mechanisms of yeast resistance to environmental stress 

    Directory of Open Access Journals (Sweden)

    Agata Piecuch

    2013-04-01

    Full Text Available Changes in environmental conditions might be a stress factor for yeast cells. There are several mechanisms of stress tolerance, developed by the cell, which activate when the stress appears. Different transcription factors coordinate the expression of stress response genes. Msn2/4p regulate the expression of the general stress response. Heat shock defense involves heat shock proteins (Hsp, controlled by Hsf1p. Osmotic shock induces the MAP kinase cascade (HOG, whereas the oxidative stress response requires the YAP network. Fungicide resistance is mediated mainly by the activity of membrane transporters and changes in the structure of the plasma membrane. 

  12. Examining the Mechanical Equilibrium of Microscopic Stresses in Molecular Simulations

    Science.gov (United States)

    Torres-Sánchez, Alejandro; Vanegas, Juan M.; Arroyo, Marino

    2015-06-01

    The microscopic stress field provides a unique connection between atomistic simulations and mechanics at the nanoscale. However, its definition remains ambiguous. Rather than a mere theoretical preoccupation, we show that this fact acutely manifests itself in local stress calculations of defective graphene, lipid bilayers, and fibrous proteins. We find that popular definitions of the microscopic stress violate the continuum statements of mechanical equilibrium, and we propose an unambiguous and physically sound definition.

  13. Plasma membrane mechanical stress activates TRPC5 channels.

    Directory of Open Access Journals (Sweden)

    Bing Shen

    Full Text Available Mechanical forces exerted on cells impose stress on the plasma membrane. Cells sense this stress and elicit a mechanoelectric transduction cascade that initiates compensatory mechanisms. Mechanosensitive ion channels in the plasma membrane are responsible for transducing the mechanical signals to electrical signals. However, the mechanisms underlying channel activation in response to mechanical stress remain incompletely understood. Transient Receptor Potential (TRP channels serve essential functions in several sensory modalities. These channels can also participate in mechanotransduction by either being autonomously sensitive to mechanical perturbation or by coupling to other mechanosensory components of the cell. Here, we investigated the response of a TRP family member, TRPC5, to mechanical stress. Hypoosmolarity triggers Ca2+ influx and cationic conductance through TRPC5. Importantly, for the first time we were able to record the stretch-activated TRPC5 current at single-channel level. The activation threshold for TRPC5 was found to be 240 mOsm for hypoosmotic stress and between -20 and -40 mmHg for pressure applied to membrane patch. In addition, we found that disruption of actin filaments suppresses TRPC5 response to hypoosmotic stress and patch pipette pressure, but does not prevent the activation of TRPC5 by stretch-independent mechanisms, indicating that actin cytoskeleton is an essential transduction component that confers mechanosensitivity to TRPC5. In summary, our findings establish that TRPC5 can be activated at the single-channel level when mechanical stress on the cell reaches a certain threshold.

  14. Measurements of residual stress in fracture mechanics coupons

    Energy Technology Data Exchange (ETDEWEB)

    Prime, Michael B [Los Alamos National Laboratory; Hill, Michael R [U.C. DAVIS; Nav Dalen, John E [HILL ENGINEERING

    2010-01-01

    This paper describes measurements of residual stress in coupons used for fracture mechanics testing. The primary objective of the measurements is to quantify the distribution of residual stress acting to open (and/or close) the crack across the crack plane. The slitting method and the contour method are two destructive residual stress measurement methods particularly capable of addressing that objective, and these were applied to measure residual stress in a set of identically prepared compact tension (C(T)) coupons. Comparison of the results of the two measurement methods provides some useful observations. Results from fracture mechanics tests of residual stress bearing coupons and fracture analysis, based on linear superposition of applied and residual stresses, show consistent behavior of coupons having various levels of residual stress.

  15. The impact of static stress change, dynamic stress change, and the background stress on aftershock focal mechanisms

    Science.gov (United States)

    Hardebeck, Jeanne L.

    2014-01-01

    The focal mechanisms of earthquakes in Southern California before and after four M ≥ 6.7 main shocks provide insight into how fault systems respond to stress and changes in stress. The main shock static stress changes have two observed impacts on the seismicity: changing the focal mechanisms in a given location to favor those aligned with the static stress change and changing the spatial distribution of seismicity to favor locations where the static stress change aligns with the background stress. The aftershock focal mechanisms are significantly aligned with the static stress changes for absolute stress changes of ≥ 0.02 MPa, for up to ~20 years following the main shock. The dynamic stress changes have similar, although smaller, effects on the local focal mechanisms and the spatial seismicity distribution. Dynamic stress effects are best observed at long periods (30–60 s) and for metrics based on repeated stress cycling in the same direction. This implies that dynamic triggering operates, at least in part, through cyclic shear stress loading in the direction of fault slip. The background stress also strongly controls both the preshock and aftershock mechanisms. While most aftershock mechanisms are well oriented in the background stress field, 10% of aftershocks are identified as poorly oriented outliers, which may indicate limited heterogeneity in the postmain shock stress field. The fault plane orientations of the outliers are well oriented in the background stress, while their slip directions are not, implying that the background stress restricts the distribution of available fault planes.

  16. Mapping the Indicators. An Analysis of Sustainable Development Requirements of Selected Market Mechanisms and Multilateral Institutions

    DEFF Research Database (Denmark)

    Arens, Christof; Mersmann, Florian; Beuermann, Christiane

    in achieving sustainable development based on their national development priorities and strategies. However, complying with the second objective turned out to be problematic. Registered projects appeared that had no proven sustainable development benefits, or even perceived negative impacts. Consequently....... A robust assessment of the impact of sustainable development in CDM projects is important to ensure the social and ecological integrity of the mechanism and compliance with the objectives of sustainable development as stated in the Kyoto Protocol. Research and best practice experience into how sustainable...... development issues are integrated into mitigation actions through the CDM Sustainable Development Tool and other respective standards can help inform the development of Nationally Appropriate Mitigation Actions and future mechanisms on sustainable development assessment methods. As sustainable development...

  17. Stressors and coping mechanisms associated with perceived stress in Latinos.

    Science.gov (United States)

    Perez, Sasha M; Gavin, Jennifer K; Diaz, Vanessa A

    2015-01-01

    To evaluate the relationship between causes of perceived stress and the coping mechanisms used by Latino adults with perceived stress. This cross-sectional survey was conducted on a convenience sample of 200 Latino adults (aged ≥18 years). They were recruited from clinics, migrant camps, community events, and churches located in Charleston, S.C. This survey included questions regarding causes of perceived stress, perceived stress (Perceived Stress Scale 10), coping mechanisms (Brief COPE), and depression (Perceived Health Questionnaire 9). High perceived stress (PSS ≥15) was the primary outcome measure. Coping mechanisms and stressors were secondary outcomes. Most (92%) of the sample was born outside the United States, and 66% reported high perceived stress. Stressors associated with high perceived stress included discrimination (P=.0010), lack of insurance (P=.0193), health problems (P=.0058), and lack of money (P=.0015). The most frequently utilized coping mechanisms were self-distraction (54.77%), active coping (69.85%), positive reframing (56.78%), planning (63.82%), acceptance (57.87%), and religion (57.79%). Latinos with higher perceived stress were more likely to report discrimination (OR: 3.401; 95%CI 1.285-9.004) and health problems (OR: 2.782; 95%CI 1.088-7.111) as stressors, and to use denial as a coping mechanism (OR: 2.904; 95%CI 1.280-6.589). An increased prevalence of perceived stress among the Latinos evaluated in this study was associated with using denial as a coping mechanism, and encountering discrimination and health problems as sources of perceived stress. Most individuals responded to stressors by utilizing a variety of both adaptive and maladaptive coping mechanisms.

  18. Stress-constrained topology optimization for compliant mechanism design

    DEFF Research Database (Denmark)

    de Leon, Daniel M.; Alexandersen, Joe; Jun, Jun S.

    2015-01-01

    This article presents an application of stress-constrained topology optimization to compliant mechanism design. An output displacement maximization formulation is used, together with the SIMP approach and a projection method to ensure convergence to nearly discrete designs. The maximum stress...... is approximated using a normalized version of the commonly-used p-norm of the effective von Mises stresses. The usual problems associated with topology optimization for compliant mechanism design: one-node and/or intermediate density hinges are alleviated by the stress constraint. However, it is also shown...

  19. Mechanical contribution to lumbar stress injuries in female gymnasts.

    Science.gov (United States)

    Hall, S J

    1986-12-01

    Because female gymnasts as a group display higher than average incidences of stress-related pathologies of the lumbar spine, it was of interest to evaluate mechanical factors which are potential contributors. Lumbar hyperextension and impact forces were quantified for performances of five commonly executed gymnastics skills by four competitive collegiate women gymnasts. The skills performed were the front walkover, the back walkover, and the front handspring, the back handspring, and the handspring vault. Wielke's (1983) radius method was used to quantify lumbar curvatures from film data during normal relaxed standing postures and during subject performances of the five selected skills. A force platform was used to monitor vertical and lateral ground reaction forces at the terminations of the respective skill performances. Of the skills examined, the handspring vault produced the highest vertical and lateral impact forces, and the back handspring and back walkover required the greatest amounts of lumbar hyperextension. During the front and back walkovers and during the back handspring, maximum lumbar hyperextension occurred very close to the time that impact force was sustained by either the hands or the feet.

  20. Neural traces of stress: cortisol related sustained enhancement of amygdala-hippocampal functional connectivity

    Directory of Open Access Journals (Sweden)

    Sharon eVaisvaser

    2013-07-01

    Full Text Available Stressful experiences modulate neuro-circuitry function, and the temporal trajectory of these alterations, elapsing from early disturbances to late recovery, heavily influences resilience and vulnerability to stress. Such effects of stress may depend on processes that are engaged during resting-state, through active recollection of past experiences and anticipation of future events, all known to involve the default mode network (DMN. By inducing social stress and acquiring resting-state fMRI before stress, immediately following it, and two hours later, we expanded the time-window for examining the trajectory of the stress response. Throughout the study repeated cortisol samplings and self-reports of stress levels were obtained from 51 healthy young males. Post-stress alterations were investigated by whole brain resting-state functional connectivity of two central hubs of the DMN: the posterior cingulate cortex and hippocampus. Results indicate a 'recovery' pattern of DMN connectivity, in which all alterations, ascribed to the intervening stress, returned to pre-stress levels. The only exception to this pattern was a stress-induced rise in amygdala-hippocampal connectivity, which was sustained for as long as two hours following stress induction. Furthermore, this sustained enhancement of limbic connectivity was inversely correlated to individual stress-induced cortisol responsiveness (AUCi and characterized only the group lacking such increased cortisol (i.e., non-responders. Our observations provide evidence of a prolonged post-stress response profile, characterized by both the comprehensive balance of most DMN functional connections and the distinct time and cortisol dependent ascent of intra-limbic connectivity. These novel insights into neuro-endocrine relations are another milestone in the ongoing search for individual markers in stress-related psychopathologies.

  1. Mechanical design of the stressed-lap polishing tool

    Science.gov (United States)

    Wang, Lei; Zhu, Yong-tian; Zhang, Qing-feng

    2005-12-01

    We present an overview of the engineering design of stressed lap developed at Nanjing Institute of Astronomical Optics and Technology. Stressed lap consists of two parts: active deformable lap, driving-adjusting mechanism. The finite element model for active deformable lap is constructed, and the performance of lap deforming is discussed. Descriptions about mechanical structure of driving-adjusting mechanism are given. Now, stressed-lap polishing tool has been used to accomplish a fast parabolic mirror in Nanjing. The φ910mm F/2 parabolic mirror has been figured to an accuracy of 22 nm.

  2. Mechanical Stress Promotes Cisplatin-Induced Hepatocellular Carcinoma Cell Death

    Science.gov (United States)

    Riad, Sandra; Bougherara, Habiba

    2015-01-01

    Cisplatin (CisPt) is a commonly used platinum-based chemotherapeutic agent. Its efficacy is limited due to drug resistance and multiple side effects, thereby warranting a new approach to improving the pharmacological effect of CisPt. A newly developed mathematical hypothesis suggested that mechanical loading, when coupled with a chemotherapeutic drug such as CisPt and immune cells, would boost tumor cell death. The current study investigated the aforementioned mathematical hypothesis by exposing human hepatocellular liver carcinoma (HepG2) cells to CisPt, peripheral blood mononuclear cells, and mechanical stress individually and in combination. HepG2 cells were also treated with a mixture of CisPt and carnosine with and without mechanical stress to examine one possible mechanism employed by mechanical stress to enhance CisPt effects. Carnosine is a dipeptide that reportedly sequesters platinum-based drugs away from their pharmacological target-site. Mechanical stress was achieved using an orbital shaker that produced 300 rpm with a horizontal circular motion. Our results demonstrated that mechanical stress promoted CisPt-induced death of HepG2 cells (~35% more cell death). Moreover, results showed that CisPt-induced death was compromised when CisPt was left to mix with carnosine 24 hours preceding treatment. Mechanical stress, however, ameliorated cell death (20% more cell death). PMID:25685789

  3. Mechanical Stress Promotes Cisplatin-Induced Hepatocellular Carcinoma Cell Death

    Directory of Open Access Journals (Sweden)

    Laila Ziko

    2015-01-01

    Full Text Available Cisplatin (CisPt is a commonly used platinum-based chemotherapeutic agent. Its efficacy is limited due to drug resistance and multiple side effects, thereby warranting a new approach to improving the pharmacological effect of CisPt. A newly developed mathematical hypothesis suggested that mechanical loading, when coupled with a chemotherapeutic drug such as CisPt and immune cells, would boost tumor cell death. The current study investigated the aforementioned mathematical hypothesis by exposing human hepatocellular liver carcinoma (HepG2 cells to CisPt, peripheral blood mononuclear cells, and mechanical stress individually and in combination. HepG2 cells were also treated with a mixture of CisPt and carnosine with and without mechanical stress to examine one possible mechanism employed by mechanical stress to enhance CisPt effects. Carnosine is a dipeptide that reportedly sequesters platinum-based drugs away from their pharmacological target-site. Mechanical stress was achieved using an orbital shaker that produced 300 rpm with a horizontal circular motion. Our results demonstrated that mechanical stress promoted CisPt-induced death of HepG2 cells (~35% more cell death. Moreover, results showed that CisPt-induced death was compromised when CisPt was left to mix with carnosine 24 hours preceding treatment. Mechanical stress, however, ameliorated cell death (20% more cell death.

  4. Dynamics of mechanical signal transmission through prestressed stress fibers.

    Directory of Open Access Journals (Sweden)

    Yongyun Hwang

    Full Text Available Transmission of mechanical stimuli through the actin cytoskeleton has been proposed as a mechanism for rapid long-distance mechanotransduction in cells; however, a quantitative understanding of the dynamics of this transmission and the physical factors governing it remains lacking. Two key features of the actin cytoskeleton are its viscoelastic nature and the presence of prestress due to actomyosin motor activity. We develop a model of mechanical signal transmission through prestressed viscoelastic actin stress fibers that directly connect the cell surface to the nucleus. The analysis considers both temporally stationary and oscillatory mechanical signals and accounts for cytosolic drag on the stress fibers. To elucidate the physical parameters that govern mechanical signal transmission, we initially focus on the highly simplified case of a single stress fiber. The results demonstrate that the dynamics of mechanical signal transmission depend on whether the applied force leads to transverse or axial motion of the stress fiber. For transverse motion, mechanical signal transmission is dominated by prestress while fiber elasticity has a negligible effect. Conversely, signal transmission for axial motion is mediated uniquely by elasticity due to the absence of a prestress restoring force. Mechanical signal transmission is significantly delayed by stress fiber material viscosity, while cytosolic damping becomes important only for longer stress fibers. Only transverse motion yields the rapid and long-distance mechanical signal transmission dynamics observed experimentally. For simple networks of stress fibers, mechanical signals are transmitted rapidly to the nucleus when the fibers are oriented largely orthogonal to the applied force, whereas the presence of fibers parallel to the applied force slows down mechanical signal transmission significantly. The present results suggest that cytoskeletal prestress mediates rapid mechanical signal transmission

  5. Salicylic acid-induced abiotic stress tolerance and underlying mechanisms in plants

    Science.gov (United States)

    Khan, M. Iqbal R.; Fatma, Mehar; Per, Tasir S.; Anjum, Naser A.; Khan, Nafees A.

    2015-01-01

    Abiotic stresses (such as metals/metalloids, salinity, ozone, UV-B radiation, extreme temperatures, and drought) are among the most challenging threats to agricultural system and economic yield of crop plants. These stresses (in isolation and/or combination) induce numerous adverse effects in plants, impair biochemical/physiological and molecular processes, and eventually cause severe reductions in plant growth, development and overall productivity. Phytohormones have been recognized as a strong tool for sustainably alleviating adverse effects of abiotic stresses in crop plants. In particular, the significance of salicylic acid (SA) has been increasingly recognized in improved plant abiotic stress-tolerance via SA-mediated control of major plant-metabolic processes. However, the basic biochemical/physiological and molecular mechanisms that potentially underpin SA-induced plant-tolerance to major abiotic stresses remain least discussed. Based on recent reports, this paper: (a) overviews historical background and biosynthesis of SA under both optimal and stressful environments in plants; (b) critically appraises the role of SA in plants exposed to major abiotic stresses; (c) cross-talks potential mechanisms potentially governing SA-induced plant abiotic stress-tolerance; and finally (d) briefly highlights major aspects so far unexplored in the current context. PMID:26175738

  6. Sustained attention ability in schizophrenia: Investigation of conflict monitoring mechanisms.

    Science.gov (United States)

    Hoonakker, Marc; Doignon-Camus, Nadège; Marques-Carneiro, José Eduardo; Bonnefond, Anne

    2017-09-01

    The main goal of the current study was to assess, with a time-on-task approach, sustained attention ability in schizophrenia, and to investigate conflict monitoring underlying this ability. Behavioral and event-related potentials data (N2 and P3a amplitudes) were recorded in a long-lasting sustained attention Go/NoGo task (sustained attention to response task, SART), over a period of 30min, in 29 patients with schizophrenia and 29 pair-matched healthy subjects. Our results revealed spared sustained attention ability in patients throughout the task. Impairment of conflict detection (N2) in patients was particularly significant at the end of the task. Furthermore, both schizophrenia and healthy subjects exhibited a decline in conflict detection from the beginning to the middle of the task. Whereas controls' conflict detection recovered in the last part of the task, patients' did not, suggesting a deficit in recovery processes reflecting a lack of additional resources sustained attention Go/NoGo task. Conflict resolution (P3a) was preserved throughout the task in both groups. Conflict monitoring processes are increasingly impaired in schizophrenia during a long-lasting sustained attention Go/NoGo task. This impairment at the end of the task may rely on deficit in recovery processes, rather than a deficit in conflict detection per se in schizophrenia. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

  7. An Evaluation Of Academic Stress And Coping Mechanism Among ...

    African Journals Online (AJOL)

    The study assessed and evaluated academic stress coping mechanisms adopted by married female students in Nigerian tertiary institutions. This was with the aim of exploring the influence of academic stress on married female students‟ academic performance and their coping strategies used to enhance their academic ...

  8. Surge Nozzle NDE Specimen Mechanical Stress Improvement Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Fredette, Lee F.

    2011-07-14

    The purpose of this project was to perform a finite element analysis of a pressurized water reactor pressurizer surge nozzle mock-up to predict both the weld residual stresses created in its construction and the final stress state after the application of the Mechanical Stress Improvement Process (MSIP). Strain gages were applied to the inner diameter of the mock-up to record strain changes during the MSIP. These strain readings were used in an attempt to calculate the final stress state of the mock-up as well.

  9. Stress Biology and Aging Mechanisms: Toward Understanding the Deep Connection Between Adaptation to Stress and Longevity

    Science.gov (United States)

    2014-01-01

    The rate of biological aging is modulated in part by genes interacting with stressor exposures. Basic research has shown that exposure to short-term stress can strengthen cellular responses to stress (“hormetic stress”). Hormetic stress promotes longevity in part through enhanced activity of molecular chaperones and other defense mechanisms. In contrast, prolonged exposure to stress can overwhelm compensatory responses (“toxic stress”) and shorten lifespan. One key question is whether the stressors that are well understood in basic models of aging can help us understand psychological stressors and human health. The psychological stress response promotes regulatory changes important in aging (e.g., increases in stress hormones, inflammation, oxidative stress, insulin). The negative effects of severe stress are well documented in humans. Potential positive effects of acute stress (stress resistance) are less studied, especially at the cellular level. Can stress resistance slow the rate of aging in humans, as it does in model organisms? If so, how can we promote stress resistance in humans? We urge a new research agenda embracing the continuum from cellular stress to psychological stress, using basic and human research in tandem. This will require interdisciplinary novel approaches that hold much promise for understanding and intervening in human chronic disease. PMID:24833580

  10. Behavioral effects of chronic adolescent stress are sustained and sexually dimorphic

    Science.gov (United States)

    Bourke, Chase H.; Neigh, Gretchen N.

    2011-01-01

    Evidence suggests that women are more susceptible to stress-related disorders than men. Animal studies demonstrate a similar female sensitivity to stress and have been used to examine the underlying neurobiology of sex-specific effects of stress. Although our understanding of the sex-specific effects of chronic adolescent stress has grown in recent years, few studies have reported the effects of adolescent stress on depressive-like behavior. The purpose of this study was to determine if a chronic mixed modality stressor (consisting of isolation, restraint, and social defeat) during adolescence (PND37-49) resulted in differential and sustained changes in depressive-like behavior in male and female Wistar rats. Female rats exposed to chronic adolescent stress displayed decreased sucrose consumption, hyperactivity in the elevated plus maze, decreased activity in the forced swim test, and a blunted corticosterone response to an acute forced swim stress compared to controls during both adolescence (PND48-57) and adulthood (PND96-104). Male rats exposed to chronic adolescent stress did not manifest significant behavioral changes at either the end of adolescence or in adulthood. These data support the proposition that adolescence may be a stress sensitive period for females and exposure to stress during adolescence results in behavioral effects that persist in females. Studies investigating the sex-specific effects of chronic adolescent stress may lead to a better understanding of the sexually dimorphic incidence of depressive and anxiety disorders in humans and ultimately improve prevention and treatment strategies. PMID:21466807

  11. Flexibility mechanisms and sustainable development: Lessons from five AIJ projects

    NARCIS (Netherlands)

    Gupta, J.; van Beukering, P.J.H.; van Asselt, H.D.; Brander, L.M.; Hess, S.M.; van der Leeuw, K.

    2008-01-01

    Do 'Activities Implemented Jointly' (AIJ) projects contribute to sustainable development in the host countries? Which factors have contributed to the success or failure of the projects? Five AIJ projects were examined, accounting for 90% of the total AIJ expenditure of the Dutch government. The

  12. Stress analysis in a functionally graded disc under mechanical loads ...

    Indian Academy of Sciences (India)

    Stress analysis in a functionally graded disc under mechanical loads and a steady state temperature distribution. HASAN ÇALLIO ˘GLU. Department of Mechanical Engineering, Pamukkale University, 20070,. Denizli, Turkey e-mail: hcallioglu@pau.edu.tr. MS received 25 November 2009; revised 12 August 2010; accepted.

  13. Development of Mechanical Stress Simulator for Surface-Mount Devices

    Science.gov (United States)

    Yamamoto, Keiji

    1995-04-01

    A mechanical stress simulator for surface-mount devices was developed, which employed the finite-element method. The moisture distribution stage can calculate the moisture distribution of the LSI package exposed to temperature and humidity conditions. The heat conduction stage determines the time-dependent temperature distribution of the package immersed in a solder bath. Using the moisture and temperature distributions thus calculated, the mechanical stress stage gives the mechanical stress distribution in the package. Two groups of samples were prepared for solder dipping experiments. In one group, after dry baking for initialization, samples absorbed moisture by exposure at 30°C 85% (absorption process). In the other group, samples were exposed at 85°C 85% for 168 h and then dry-baked at 70°C (desorption process). These two groups have different moisture distributions in their packages. The results of solder dipping experiments are analyzed from the calculated mechanical stress values. In the absorption process, calculated maximum von Mises equivalent stress over the sectional molding compound \\barσ_max increases monotonically with absorption time. Then, \\barσ_max approaches its saturated value as absorption time tends to infinity. In the desorption process, \\barσ_max decreases with desorption time and approaches the thermal stress value when desorption time tends to infinity. These calculations explain the effect of moisture distribution on package cracking.

  14. Polymers under mechanical stress- an NMR investigation

    Energy Technology Data Exchange (ETDEWEB)

    Boehme, Ute; Scheler, Ulrich [Leibniz Institute of Polymer Research Dresden (Germany); Xu, Bo; Leisen, Johannes; Beckham, Haskell W. [Georgia Institute of Technology, Atlanta, Georgia (United States)

    2010-07-01

    Low-field NMR using permanent magnets in Halbach arrangements permit NMR investigation without the limits present in high-field NMR. The lower field in conjunction with confined stray field permit the application of NMR, in particular relaxation NMR in a stretching apparatus and a rheometer. Crystalline and amorphous fraction of semi-crystalline polymers are distinguished by their transverse relaxation times. Upon mechanical load the relaxation times of the amorphous fraction changes as seen in in-situ measurements on polypropylene rods. During the formation of a neck the crystalline fraction becomes more prominent.

  15. Stress and Memory: Behavioral Effects and Neurobiological Mechanisms

    Science.gov (United States)

    Sandi, Carmen; Pinelo-Nava, M. Teresa

    2007-01-01

    Stress is a potent modulator of learning and memory processes. Although there have been a few attempts in the literature to explain the diversity of effects (including facilitating, impairing, and lack of effects) described for the impact of stress on memory function according to single classification criterion, they have proved insufficient to explain the whole complexity of effects. Here, we review the literature in the field of stress and memory interactions according to five selected classifying factors (source of stress, stressor duration, stressor intensity, stressor timing with regard to memory phase, and learning type) in an attempt to develop an integrative model to understand how stress affects memory function. Summarizing on those conditions in which there was enough information, we conclude that high stress levels, whether intrinsic (triggered by the cognitive challenge) or extrinsic (induced by conditions completely unrelated to the cognitive task), tend to facilitate Pavlovian conditioning (in a linear-asymptotic manner), while being deleterious for spatial/explicit information processing (which with regard to intrinsic stress levels follows an inverted U-shape effect). Moreover, after reviewing the literature, we conclude that all selected factors are essential to develop an integrative model that defines the outcome of stress effects in memory processes. In parallel, we provide a brief review of the main neurobiological mechanisms proposed to account for the different effects of stress in memory function. Glucocorticoids were found as a common mediating mechanism for both the facilitating and impairing actions of stress in different memory processes and phases. Among the brain regions implicated, the hippocampus, amygdala, and prefrontal cortex were highlighted as critical for the mediation of stress effects. PMID:18060012

  16. Stress and Memory: Behavioral Effects and Neurobiological Mechanisms

    Directory of Open Access Journals (Sweden)

    Carmen Sandi

    2007-01-01

    Full Text Available Stress is a potent modulator of learning and memory processes. Although there have been a few attempts in the literature to explain the diversity of effects (including facilitating, impairing, and lack of effects described for the impact of stress on memory function according to single classification criterion, they have proved insufficient to explain the whole complexity of effects. Here, we review the literature in the field of stress and memory interactions according to five selected classifying factors (source of stress, stressor duration, stressor intensity, stressor timing with regard to memory phase, and learning type in an attempt to develop an integrative model to understand how stress affects memory function. Summarizing on those conditions in which there was enough information, we conclude that high stress levels, whether intrinsic (triggered by the cognitive challenge or extrinsic (induced by conditions completely unrelated to the cognitive task, tend to facilitate Pavlovian conditioning (in a linear-asymptotic manner, while being deleterious for spatial/explicit information processing (which with regard to intrinsic stress levels follows an inverted U-shape effect. Moreover, after reviewing the literature, we conclude that all selected factors are essential to develop an integrative model that defines the outcome of stress effects in memory processes. In parallel, we provide a brief review of the main neurobiological mechanisms proposed to account for the different effects of stress in memory function. Glucocorticoids were found as a common mediating mechanism for both the facilitating and impairing actions of stress in different memory processes and phases. Among the brain regions implicated, the hippocampus, amygdala, and prefrontal cortex were highlighted as critical for the mediation of stress effects.

  17. Perinatal programming of neuroendocrine mechanisms connecting feeding behavior and stress

    Directory of Open Access Journals (Sweden)

    Sarah J Spencer

    2013-06-01

    Full Text Available Feeding behavior is closely regulated by neuroendocrine mechanisms that can be influenced by stressful life events. However, the feeding response to stress varies among individuals with some increasing and others decreasing food intake after stress. In addition to the impact of acute lifestyle and genetic backgrounds, the early life environment can have a life-long influence on neuroendocrine mechanisms connecting stress to feeding behavior and may partially explain these opposing feeding responses to stress. In this review I will discuss the perinatal programming of adult hypothalamic stress and feeding circuitry. Specifically I will address how early life (prenatal and postnatal nutrition, early life stress, and the early life hormonal profile can program the hypothalamic-pituitary-adrenal (HPA axis, the endocrine arm of the body’s response to stress long-term and how these changes can, in turn, influence the hypothalamic circuitry responsible for regulating feeding behavior. Thus, over- or under-feeding and / or stressful events during critical windows of early development can alter glucocorticoid (GC regulation of the HPA axis, leading to changes in the GC influence on energy storage and changes in GC negative feedback on HPA axis-derived satiety signals such as corticotropin-releasing-hormone. Furthermore, peripheral hormones controlling satiety, such as leptin and insulin are altered by early life events, and can be influenced, in early life and adulthood, by stress. Importantly, these neuroendocrine signals act as trophic factors during development to stimulate connectivity throughout the hypothalamus. The interplay between these neuroendocrine signals, the perinatal environment, and activation of the stress circuitry in adulthood thus strongly influences feeding behavior and may explain why individuals have unique feeding responses to similar stressors.

  18. Physiological, Biochemical, and Molecular Mechanisms of Heat Stress Tolerance in Plants

    Science.gov (United States)

    Hasanuzzaman, Mirza; Nahar, Kamrun; Alam, Md. Mahabub; Roychowdhury, Rajib; Fujita, Masayuki

    2013-01-01

    High temperature (HT) stress is a major environmental stress that limits plant growth, metabolism, and productivity worldwide. Plant growth and development involve numerous biochemical reactions that are sensitive to temperature. Plant responses to HT vary with the degree and duration of HT and the plant type. HT is now a major concern for crop production and approaches for sustaining high yields of crop plants under HT stress are important agricultural goals. Plants possess a number of adaptive, avoidance, or acclimation mechanisms to cope with HT situations. In addition, major tolerance mechanisms that employ ion transporters, proteins, osmoprotectants, antioxidants, and other factors involved in signaling cascades and transcriptional control are activated to offset stress-induced biochemical and physiological alterations. Plant survival under HT stress depends on the ability to perceive the HT stimulus, generate and transmit the signal, and initiate appropriate physiological and biochemical changes. HT-induced gene expression and metabolite synthesis also substantially improve tolerance. The physiological and biochemical responses to heat stress are active research areas, and the molecular approaches are being adopted for developing HT tolerance in plants. This article reviews the recent findings on responses, adaptation, and tolerance to HT at the cellular, organellar, and whole plant levels and describes various approaches being taken to enhance thermotolerance in plants. PMID:23644891

  19. Oxidative Stress-Mediated Atherosclerosis: Mechanisms and Therapies

    Science.gov (United States)

    Yang, Xinyu; Li, Yang; Li, Yanda; Ren, Xiaomeng; Zhang, Xiaoyu; Hu, Dan; Gao, Yonghong; Xing, Yanwei; Shang, Hongcai

    2017-01-01

    Atherogenesis, the formation of atherosclerotic plaques, is a complex process that involves several mechanisms, including endothelial dysfunction, neovascularization, vascular proliferation, apoptosis, matrix degradation, inflammation, and thrombosis. The pathogenesis and progression of atherosclerosis are explained differently by different scholars. One of the most common theories is the destruction of well-balanced homeostatic mechanisms, which incurs the oxidative stress. And oxidative stress is widely regarded as the redox status realized when an imbalance exists between antioxidant capability and activity species including reactive oxygen (ROS), nitrogen (RNS) and halogen species, non-radical as well as free radical species. This occurrence results in cell injury due to direct oxidation of cellular protein, lipid, and DNA or via cell death signaling pathways responsible for accelerating atherogenesis. This paper discusses inflammation, mitochondria, autophagy, apoptosis, and epigenetics as they induce oxidative stress in atherosclerosis, as well as various treatments for antioxidative stress that may prevent atherosclerosis. PMID:28878685

  20. Environmental stress in plants. Biochemical and physiological mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Cherry, J.H.

    1989-01-01

    Environmental stresses represent the most limiting factors to agricultural productivity. Environmental stresses impact not only crops which are presently being cultivated, but also are significant barriers to the introduction of crop plants into areas which are not at this time being used for agriculture. A significant problem for agriculture in the world is the major variation in crop yields from year to year due to variations in environmental stresses such as drought, flooding, salinity, and high and low temperatures. Presently, the many advances being made in plant cell and molecular biology offer new approaches to elucidate the physiological, biochemical and genetic mechanisms of tolerance to environmental stresses. We believe within the early years of the twenty-first century that many genetic lines of agronomic plants will be improved by the introduction of stable genes that provide resistance to most stresses. These new and improved genetic lines of crop plants will greatly stabilize agricultural productivity worldwide. (orig./EF).

  1. Mechanization and new technologies for the control and the sustainability of agricultural and forestry systems

    Directory of Open Access Journals (Sweden)

    The Editors

    2016-05-01

    Full Text Available Abstract Book of the Congress:Mechanization and new technologies for the control and the sustainability of agricultural and forestry systems Alghero, Italy, 29th May - 1st June 2016

  2. Effects of mechanical stresses on lithium ion batteries

    Science.gov (United States)

    Kim, Hyoncheol

    Structural batteries are multifunctional materials that are expected to perform multiple roles, i.e. power generation and mechanical support. Properly realized, the concept can dramatically improve gravimetric properties by elimination of parasitic masses tolerated in conventional devices. However, the significant structural loads that such batteries would be expected to bear, given their multiple roles, would exceed those experienced by conventional batteries, and thus must be studied and understood in the context of device safety, lifetime and cost. Key sources of mechanical stresses were identified and quantified in this effort, including manufacturing-induced loads, thermal loads, kinetic loads and structural loads. It was found that stresses due to compression during electrode fabrication can be as large as 2000 MPa, thus having the potential to induce mechanical failure of constituent materials, while stresses induced by structural loads in an unmanned vehicle example studied, were less than 1 MPa. Thermal stresses were found in one embodiment, to exceed 100 MPa, largely due to mechanical confinement of batteries embedded for structural support. Supporting experiments were conceived in this work to study the effect of loads on electrochemical performance. A novel design of a structural battery was developed, to simultaneously conduct mechanical and electrochemical experiments. Diffusion coefficients were determined while various loadings were applied. Also, stresses exerted on the battery were observed while the battery was charged and discharged. Statistically meaningful correlation was not observed for diffusion coefficients with respect to stresses, but forces applied to carbon fiber significantly varied during charging/discharging of batteries, and the magnitude of variance of force was strongly correlated with the number of charges. Molecular dynamics simulations, finally, were performed to examine findings from experiments. Diffusion coefficients of

  3. Effect of applied mechanical stress on absorption coefficient of compounds

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Manoj Kumar, E-mail: mkgupta.sliet@gmail.com [Department of Applied Sciences, Bhai Gurdas Institute of Engineering and Technology, Sangrur (India); Singh, Gurinderjeet; Dhaliwal, A. S.; Kahlon, K. S. [Department of Physics, Sant Longowal Institute of Engineering & Technology Deemed University, Longowal (Sangrur) India-148106 (India)

    2015-08-28

    The absorption coefficient of given materials is the parameter required for the basic information. The measurement of absorption coefficient of compounds Al{sub 2}O{sub 3}, CaCO{sub 3}, ZnO{sub 2}, SmO{sub 2} and PbO has been taken at different incident photon energies 26, 59.54, 112, 1173, 1332keV. The studies involve the measurements of absorption coefficient of the self supporting samples prepared under different mechanical stress. This mechanical stress is render in terms of pressure up to 0-6 ton by using hydraulic press. Measurements shows that absorption coefficient of a material is directly proportional to applied mechanical stress on it up to some extent then become independent. Experimentally measured results are in fairly good agreement with in theoretical values obtained from WinXCOM.

  4. Effects, tolerance mechanisms and management of salt stress in grain legumes.

    Science.gov (United States)

    Farooq, Muhammad; Gogoi, Nirmali; Hussain, Mubshar; Barthakur, Sharmistha; Paul, Sreyashi; Bharadwaj, Nandita; Migdadi, Hussein M; Alghamdi, Salem S; Siddique, Kadambot H M

    2017-09-01

    Salt stress is an ever-present threat to crop yields, especially in countries with irrigated agriculture. Efforts to improve salt tolerance in crop plants are vital for sustainable crop production on marginal lands to ensure future food supplies. Grain legumes are a fascinating group of plants due to their high grain protein contents and ability to fix biological nitrogen. However, the accumulation of excessive salts in soil and the use of saline groundwater are threatening legume production worldwide. Salt stress disturbs photosynthesis and hormonal regulation and causes nutritional imbalance, specific ion toxicity and osmotic effects in legumes to reduce grain yield and quality. Understanding the responses of grain legumes to salt stress and the associated tolerance mechanisms, as well as assessing management options, may help in the development of strategies to improve the performance of grain legumes under salt stress. In this manuscript, we discuss the effects, tolerance mechanisms and management of salt stress in grain legumes. The principal inferences of the review are: (i) salt stress reduces seed germination (by up to more than 50%) either by inhibiting water uptake and/or the toxic effect of ions in the embryo, (ii) salt stress reduces growth (by more than 70%), mineral uptake, and yield (by 12-100%) due to ion toxicity and reduced photosynthesis, (iii) apoplastic acidification is a good indicator of salt stress tolerance, (iv) tolerance to salt stress in grain legumes may develop through excretion and/or compartmentalization of toxic ions, increased antioxidant capacity, accumulation of compatible osmolytes, and/or hormonal regulation, (v) seed priming and nutrient management may improve salt tolerance in grain legumes, (vi) plant growth promoting rhizobacteria and arbuscular mycorrhizal fungi may help to improve salt tolerance due to better plant nutrient availability, and (vii) the integration of screening, innovative breeding, and the development of

  5. Persisting in papyrus: size, oxidative stress, and fitness in freshwater organisms adapted to sustained hypoxia.

    Science.gov (United States)

    Joyner-Matos, Joanna; Chapman, Lauren J

    2013-08-01

    Aquatic hypoxia is generally viewed as stressful for aerobic organisms. However, hypoxia may also benefit organisms by decreasing cellular stress, particularly that related to free radicals. Thus, an ideal habitat may have the minimum O2 necessary to both sustain aerobic metabolism and reduce the need to scavenge free radicals and repair free radical damage. The ability of aquatic organisms to sustain aerobic metabolism relates in part to the ability to maximize gas diffusion, which can be facilitated by small body size when O2 uptake occurs across the body surface, by a large gill surface area, or by the ability to use atmospheric air. We use water-breathing organisms in chronically hypoxic papyrus (Cyperus papyrus) swamps of East Africa to test the hypothesis that cellular-level benefits of hypoxia may translate into increased fitness, especially for small organisms. A review of recent studies of fingernail clams (Sphaerium sp.) shows that clams living in sustained hypoxia have minimized oxidative stress and that these cellular-level benefits may lead to increased fitness. We suggest that organisms in the extreme conditions in the papyrus swamps provide a unique opportunity to challenge the conventional classification of hypoxic habitats as 'stressful' and normoxic habitats as 'optimal.' Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Epigenetic and chromatin-based mechanisms in environmental stress adaptation and stress memory in plants.

    Science.gov (United States)

    Lämke, Jörn; Bäurle, Isabel

    2017-06-27

    Plants frequently have to weather both biotic and abiotic stressors, and have evolved sophisticated adaptation and defense mechanisms. In recent years, chromatin modifications, nucleosome positioning, and DNA methylation have been recognized as important components in these adaptations. Given their potential epigenetic nature, such modifications may provide a mechanistic basis for a stress memory, enabling plants to respond more efficiently to recurring stress or even to prepare their offspring for potential future assaults. In this review, we discuss both the involvement of chromatin in stress responses and the current evidence on somatic, intergenerational, and transgenerational stress memory.

  7. Molecular mechanisms of mTOR regulation by stress.

    Science.gov (United States)

    Heberle, Alexander Martin; Prentzell, Mirja Tamara; van Eunen, Karen; Bakker, Barbara Marleen; Grellscheid, Sushma Nagaraja; Thedieck, Kathrin

    2015-01-01

    Tumors are prime examples of cell growth in unfavorable environments that elicit cellular stress. The high metabolic demand and insufficient vascularization of tumors cause a deficiency of oxygen and nutrients. Oncogenic mutations map to signaling events via mammalian target of rapamycin (mTOR), metabolic pathways, and mitochondrial function. These alterations have been linked with cellular stresses, in particular endoplasmic reticulum (ER) stress, hypoxia, and oxidative stress. Yet tumors survive these challenges and acquire highly energy-demanding traits, such as overgrowth and invasiveness. In this review we focus on stresses that occur in cancer cells and discuss them in the context of mTOR signaling. Of note, many tumor traits require mTOR complex 1 (mTORC1) activity, but mTORC1 hyperactivation eventually sensitizes cells to apoptosis. Thus, mTORC1 activity needs to be balanced in cancer cells. We provide an overview of the mechanisms contributing to mTOR regulation by stress and suggest a model wherein stress granules function as guardians of mTORC1 signaling, allowing cancer cells to escape stress-induced cell death.

  8. Composite Overwrap Pressure Vessels: Mechanics and Stress Rupture Lifting Philosophy

    Science.gov (United States)

    Thesken, John C.; Murthy, Pappu L. N.; Phoenix, S. L.

    2009-01-01

    The NASA Engineering and Safety Center (NESC) has been conducting an independent technical assessment to address safety concerns related to the known stress rupture failure mode of filament wound pressure vessels in use on Shuttle and the International Space Station. The Shuttle s Kevlar-49 (DuPont) fiber overwrapped tanks are of particular concern due to their long usage and the poorly understood stress rupture process in Kevlar-49 filaments. Existing long term data show that the rupture process is a function of stress, temperature and time. However due to the presence of load sharing liners and the complex manufacturing procedures, the state of actual fiber stress in flight hardware and test articles is not clearly known. Indeed nonconservative life predictions have been made where stress rupture data and lifing procedures have ignored the contribution of the liner in favor of applied pressure as the controlling load parameter. With the aid of analytical and finite element results, this paper examines the fundamental mechanical response of composite overwrapped pressure vessels including the influence of elastic plastic liners and degraded/creeping overwrap properties. Graphical methods are presented describing the non-linear relationship of applied pressure to Kevlar-49 fiber stress/strain during manufacturing, operations and burst loadings. These are applied to experimental measurements made on a variety of vessel systems to demonstrate the correct calibration of fiber stress as a function of pressure. Applying this analysis to the actual qualification burst data for Shuttle flight hardware revealed that the nominal fiber stress at burst was in some cases 23 percent lower than what had previously been used to predict stress rupture life. These results motivate a detailed discussion of the appropriate stress rupture lifing philosophy for COPVs including the correct transference of stress rupture life data between dissimilar vessels and test articles.

  9. Composite Overwrap Pressure Vessels: Mechanics and Stress Rupture Lifing Philosophy

    Science.gov (United States)

    Thesken, John C.; Murthy, Pappu L. N.; Phoenix, Leigh

    2007-01-01

    The NASA Engineering and Safety Center (NESC) has been conducting an independent technical assessment to address safety concerns related to the known stress rupture failure mode of filament wound pressure vessels in use on Shuttle and the International Space Station. The Shuttle's Kevlar-49 fiber overwrapped tanks are of particular concern due to their long usage and the poorly understood stress rupture process in Kevlar-49 filaments. Existing long term data show that the rupture process is a function of stress, temperature and time. However due to the presence of load sharing liners and the complex manufacturing procedures, the state of actual fiber stress in flight hardware and test articles is not clearly known. Indeed non-conservative life predictions have been made where stress rupture data and lifing procedures have ignored the contribution of the liner in favor of applied pressure as the controlling load parameter. With the aid of analytical and finite element results, this paper examines the fundamental mechanical response of composite overwrapped pressure vessels including the influence of elastic-plastic liners and degraded/creeping overwrap properties. Graphical methods are presented describing the non-linear relationship of applied pressure to Kevlar-49 fiber stress/strain during manufacturing, operations and burst loadings. These are applied to experimental measurements made on a variety of vessel systems to demonstrate the correct calibration of fiber stress as a function of pressure. Applying this analysis to the actual qualification burst data for Shuttle flight hardware revealed that the nominal fiber stress at burst was in some cases 23% lower than what had previously been used to predict stress rupture life. These results motivate a detailed discussion of the appropriate stress rupture lifing philosophy for COPVs including the correct transference of stress rupture life data between dissimilar vessels and test articles.

  10. Intraplate stress field in South America from earthquake focal mechanisms

    Science.gov (United States)

    Assumpção, Marcelo; Dias, Fábio L.; Zevallos, Ivan; Naliboff, John B.

    2016-11-01

    We present an updated compilation of earthquake focal mechanisms in Brazil together with focal mechanisms from the sub-Andean region (mainly from global CMT catalogs). All earthquakes in the sub-Andean region show reverse (majority) or strike-slip faulting mechanisms. Focal mechanisms in Brazil show reverse, strike-slip and normal faulting. Focal mechanisms of nearby earthquakes in the same tectonic environment were grouped and inverted for the stress tensor. In the sub-Andean region, stresses are compressional, as expected, with the principal major compression (S1) roughly E-W, on average. A slight rotation of S1 can be observed and is controlled by the orientation of the Andean plateau. In the sub-Andean region, the intermediate principal stress (S2) is also compressional (i.e., larger than the lithostatic pressure, Sv), a feature that is not always reproduced in numerical models published in the literature. In mid-plate South America stresses seem to vary in nature and orientation. In SE Brazil and the Chaco-Pantanal basins, S1 tends to be oriented roughly E-W with S2 approximately equal to S3. This stress pattern changes to purely compressional (both SHmax and Shmin larger than Sv) in the São Francisco craton. A rotation of SHmax from E-W to SE-NW is suggested towards the Amazon region. Along the Atlantic margin, the regional stresses are very much affected by coastal effects (due to continent/ocean spreading stresses as well as flexural effects from sediment load at the continental margin). This coastal effect tends to make SHmax parallel to the coastline and Shmin (usually S3) perpendicular to the coastline. Few breakout data and in-situ measurements are available in Brazil and are generally consistent with the pattern derived from the earthquake focal mechanisms. Although numerical models of global lithospheric stresses tend to reproduce the main large-scale features in most mid-plate areas, the S1 rotation from ∼E-W in SE Brazil to SE-NW in the Amazon

  11. Elevated Shear Stress in Arteriovenous Fistulae: Is There Mechanical Homeostasis?

    Science.gov (United States)

    McGah, Patrick; Leotta, Daniel; Beach, Kirk; Aliseda, Alberto

    2011-11-01

    Arteriovenous fistulae are created surgically to provide access for dialysis in patients with renal failure. The current hypothesis is that the rapid remodeling occurring after the fistula creation is in part a process to restore the mechanical stresses to some preferred level (i.e. mechanical homeostasis). Given that nearly 50% of fistulae require an intervention after one year, understanding the altered hemodynamic stress is important in improving clinical outcomes. We perform numerical simulations of four patient-specific models of functioning fistulae reconstructed from 3D Doppler ultrasound scans. Our results show that the vessels are subjected to `normal' shear stresses away from the anastomosis; about 1 Pa in the veins and about 2.5 Pa in the arteries. However, simulations show that part of the anastomoses are consistently subjected to very high shear stress (>10Pa) over the cardiac cycle. These elevated values shear stresses are caused by the transitional flows at the anastomoses including flow separation and quasiperiodic vortex shedding. This suggests that the remodeling process lowers shear stress in the fistula but that it is limited as evidenced by the elevated shear at the anastomoses. This constant insult on the arterialized venous wall may explain the process of late fistula failure in which the dialysis access become occluded after years of use. Supported by an R21 Grant from NIDDK (DK081823).

  12. Lung stress and strain calculations in mechanically ventilated patients in the intensive care unit

    NARCIS (Netherlands)

    P. Blankman (Paul); D. Hasan (Djo); I.G. Bikker (Ido); D.A.M.P.J. Gommers (Diederik)

    2016-01-01

    textabstractBackground Stress and strain are parameters to describe respiratory mechanics during mechanical ventilation. Calculations of stress require invasive and difficult to perform esophageal pressure measurements. The hypothesis of the present study was: Can lung stress be reliably calculated

  13. Mechanical stresses and amorphization of ion-implanted diamond

    Science.gov (United States)

    Khmelnitsky, R. A.; Dravin, V. A.; Tal, A. A.; Latushko, M. I.; Khomich, A. A.; Khomich, A. V.; Trushin, A. S.; Alekseev, A. A.; Terentiev, S. A.

    2013-06-01

    Scanning white light interferometry and Raman spectroscopy were used to investigate the mechanical stresses and structural changes in ion-implanted natural diamonds with different impurity content. The uniform distribution of radiation defects in implanted area was obtained by the regime of multiple-energy implantation of keV He+ ions. A modification of Bosia's et al. (Nucl. Instrum. Meth. B 268 (2010) 2991) method for determining the internal stresses and the density variation in an ion-implanted diamond layer was proposed that suggests measuring, in addition to the surface swelling of a diamond plate, the radius of curvature of the plate. It is shown that, under multiple-energy implantation of He+, mechanical stresses in the implanted layer may be as high as 12 GPa. It is shown that radiation damage reaches saturation for the implantation fluence characteristic of amorphization of diamond but is appreciably lower than the graphitization threshold.

  14. Survival under stress: molecular mechanisms of metabolic rate ...

    African Journals Online (AJOL)

    Studies in my laboratory are analysing the molecular mechanisms and regulatory events that underlie transitions to and from hypometabolic states In systems including ... Our newest research targets two areas: the role of protein kinases in regulating metabolic adjustments and the role of stress-induced gene expression in ...

  15. Oxidative stress and diabetic neuropathy : pathophysiotogical mechanisms and treatment perspectives

    NARCIS (Netherlands)

    2002-01-01

    Increased oxidative stress is a mechanism that probably plays a major role in the development of diabetic complications, including peripheral neuropathy. This review summarises recent data from in vitro and in vivo studies that have been performed both to understand this aspect of the

  16. Plant resistance to cold stress: Mechanisms and environmental ...

    Indian Academy of Sciences (India)

    2004-10-28

    Oct 28, 2004 ... Home; Journals; Journal of Biosciences; Volume 29; Issue 4. Plant resistance to cold stress: Mechanisms and environmental signals triggering frost hardening and dehardening ... Keywords. Cold acclimation of plants; environmental signals; frost hardening; photoperiod; phytochrome; Scots pine ...

  17. Stress and coping mechanisms of nursing students during clinical ...

    African Journals Online (AJOL)

    Stress impacts negatively and positively depending on how effectively the individual experiencing the phenomenon is able to cope. The objective of this study was to identify the stressors in clinical practice for nursing students and the coping mechanisms used. Eighty-nine (89) students from the Department of Nursing, ...

  18. Mapping Nondominant Voices into Understanding Stress-Coping Mechanisms

    Science.gov (United States)

    Iwasaki, Yoshitaka; Bartlett, Judith; MacKay, Kelly; Mactavish, Jennifer; Ristock, Janice

    2008-01-01

    This study reports key findings from a research project, which examined the stress and coping mechanisms of several nondominant groups of individuals. The groups were based in Winnipeg, Manitoba, Canada and included (a) Aboriginal individuals with diabetes, (b) individuals with disabilities, and (c) gays and lesbians. Our analyses of personal…

  19. Stress regimes in the northwest of Iran from stress inversion of earthquake focal mechanisms

    Science.gov (United States)

    Afra, Mahsa; Moradi, Ali; Pakzad, Mehrdad

    2017-11-01

    Northwestern Iran is one of the seismically active regions with a high seismic risk in the world. This area is a part of the complex tectonic system due to the interaction between Arabia, Anatolia and Eurasia. The purpose of this study is to deduce the stress regimes in the northwestern Iran and surrounding regions from stress inversion of earthquake focal mechanisms. We compile 92 focal mechanisms data from the Global CMT catalogue and other sources and also determine the focal mechanisms of 14 earthquakes applying the moment tensor inversion. We divide the studied region into 9 zones using similarity of the horizontal GPS velocities and existing focal mechanisms. We implement two stress inversion methods, Multiple Inverse Method and Iterative Joint Inversion Method, which provide comparable results in terms of orientations of maximum horizontal stress axes SHmax. The similar results of the two methods should make us more confident about the interpretations. We consider zones of exclusion surrounding all the earthquakes according to independent focal mechanisms hypothesis. The hypothesis says that the inversion should involve events that are far enough from each other in order that any previous event doesn't affect the stress field near the earthquake under consideration. Accordingly we deal with the matter by considering zones of exclusion around all the events. The result of exclusion is only significant for eastern Anatolia. The stress regime in this region changes from oblique to strike slip faulting because of the exclusion. In eastern Anatolia, the direction of maximum horizontal stress is nearly north-south. The direction alters to east-west in Talesh region. Errors of σ1 are lower in all zones comparing with errors of σ2 and σ3 and there is a trade-off between data resolution and covariance of the model. The results substantiate the strike-slip and thrust faulting stress regimes in the northwest of Iran.

  20. STRATEGIES TO TEACH COSTING AND SUSTAINABLE DESIGN IN TODAY'S MECHANICAL ENGINEERING CURRICULUM

    Directory of Open Access Journals (Sweden)

    KIRALY Andrei

    2015-06-01

    Full Text Available Not a long time ago in “Eastern Economies”, especially in the mechanical design domain, words like costing or sustainability were practical neglected. Their importance is raising nowadays more and more and the author explains how it introduced them in mechanical engineers curriculum at the computer aided design discipline, because good habits must be implemented from young ages.

  1. Mechanism behind self-sustained oscillations in direct current glow discharges and in dusty plasmas

    CERN Document Server

    Cho, Sung Nae

    2013-01-01

    An alternative explanation to the mechanism behind self-sustained oscillations of ions in direct current (DC) glow discharges is provided. Such description is distinguished from the one provided by fluid models, where oscillations are attributed to positive feedback mechanism associated with photoionization of particles and photoemission of electrons from the cathode. Here, oscillations arise as consequence of interaction between an ion and surface charges induced by it at the bounding electrodes. Such mechanism provides an elegant explanation to why self-sustained oscillations occur only in the negative resistance region of the voltage-current characteristic curve in DC glow discharges. It is found that oscillation frequencies increase with ion's surface charge density, but at the rate which is significantly slower than it does with electric field. The presented mechanism also describes the self-sustained oscillations of ions in dusty plasmas, demonstrating that oscillations in dusty plasmas and DC glow disc...

  2. Neurobiological mechanisms supporting experience-dependent resistance to social stress.

    Science.gov (United States)

    Cooper, M A; Clinard, C T; Morrison, K E

    2015-04-16

    Humans and other animals show a remarkable capacity for resilience following traumatic, stressful events. Resilience is thought to be an active process related to coping with stress, although the cellular and molecular mechanisms that support active coping and stress resistance remain poorly understood. In this review, we focus on the neurobiological mechanisms by which environmental and social experiences promote stress resistance. In male Syrian hamsters, exposure to a brief social defeat stressor leads to increased avoidance of novel opponents, which we call conditioned defeat. Also, hamsters that have achieved dominant social status show reduced conditioned defeat as well as cellular and molecular changes in the neural circuits controlling the conditioned defeat response. We propose that experience-dependent neural plasticity occurs in the prelimbic (PL) cortex, infralimbic (IL) cortex, and ventral medial amygdala (vMeA) during the maintenance of dominance relationships, and that adaptations in these neural circuits support stress resistance in dominant individuals. Overall, behavioral treatments that promote success in competitive interactions may represent valuable interventions for instilling resilience. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

  3. A Simulation Framework for Exploring Socioecological Dynamics and Sustainability of Settlement Systems Under Stress in Ancient Mesopotamia and Beyond

    Science.gov (United States)

    Christiansen, J. H.; Altaweel, M. R.

    2007-12-01

    The presentation will describe an object-oriented, agent-based simulation framework being used to help answer longstanding questions regarding the development trajectories and sustainability of ancient Mesopotamian settlement systems. This multidisciplinary, multi-model framework supports explicit, fine-scale representations of the dynamics of key natural processes such as crop growth, hydrology, and weather, operating concurrently with social processes such as kinship-driven behaviors, farming and herding practices, social stratification, and economic and political activities carried out by social agents that represent individual persons, households, and larger-scale organizations. The framework has allowed us to explore the inherently coupled dynamics of modeled settlements and landscapes that are undergoing diverse social and environmental stresses, both acute and chronic, across multi-generational time spans. The simulation framework was originally used to address single-settlement scenarios, but has recently been extended to begin to address settlement system sustainability issues at sub-regional to regional scale, by introducing a number of new dynamic mechanisms, such as the activities of nomadic communities, that manifest themselves at these larger spatial scales. The framework is flexible and scalable and has broad applicability. It has, for example, recently been adapted to address agroeconomic sustainability of settlement systems in modern rural Thailand, testing the resilience and vulnerability of settled landscapes in the face of such perturbations as large-scale political interventions, global economic shifts, and climate change.

  4. Molecular mechanisms of ROS production and oxidative stress in diabetes.

    Science.gov (United States)

    Newsholme, Philip; Cruzat, Vinicius Fernandes; Keane, Kevin Noel; Carlessi, Rodrigo; de Bittencourt, Paulo Ivo Homem

    2016-12-15

    Oxidative stress and chronic inflammation are known to be associated with the development of metabolic diseases, including diabetes. Oxidative stress, an imbalance between oxidative and antioxidative systems of cells and tissues, is a result of over production of oxidative-free radicals and associated reactive oxygen species (ROS). One outcome of excessive levels of ROS is the modification of the structure and function of cellular proteins and lipids, leading to cellular dysfunction including impaired energy metabolism, altered cell signalling and cell cycle control, impaired cell transport mechanisms and overall dysfunctional biological activity, immune activation and inflammation. Nutritional stress, such as that caused by excess high-fat and/or carbohydrate diets, promotes oxidative stress as evident by increased lipid peroxidation products, protein carbonylation and decreased antioxidant status. In obesity, chronic oxidative stress and associated inflammation are the underlying factors that lead to the development of pathologies such as insulin resistance, dysregulated pathways of metabolism, diabetes and cardiovascular disease through impaired signalling and metabolism resulting in dysfunction to insulin secretion, insulin action and immune responses. However, exercise may counter excessive levels of oxidative stress and thus improve metabolic and inflammatory outcomes. In the present article, we review the cellular and molecular origins and significance of ROS production, the molecular targets and responses describing how oxidative stress affects cell function including mechanisms of insulin secretion and action, from the point of view of possible application of novel diabetic therapies based on redox regulation. © 2016 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.

  5. Cyanobacterial carbon concentrating mechanisms facilitate sustained CO2 depletion in eutrophic lakes

    Directory of Open Access Journals (Sweden)

    A. M. Morales-Williams

    2017-06-01

    Full Text Available Phytoplankton blooms are increasing in frequency, intensity, and duration in aquatic ecosystems worldwide. In many eutrophic lakes, these high levels of primary productivity correspond to periods of CO2 depletion in surface waters. Cyanobacteria and other groups of phytoplankton have the ability to actively transport bicarbonate (HCO3− across their cell membrane when CO2 concentrations are limiting, possibly giving them a competitive advantage over algae not using carbon concentrating mechanisms (CCMs. To investigate whether CCMs can maintain phytoplankton bloom biomass under CO2 depletion, we measured the δ13C signatures of dissolved inorganic carbon (δ13CDIC and phytoplankton particulate organic carbon (δ13Cphyto in 16 mesotrophic to hypereutrophic lakes during the ice-free season of 2012. We used mass–balance relationships to determine the dominant inorganic carbon species used by phytoplankton under CO2 stress. We found a significant positive relationship between phytoplankton biomass and phytoplankton δ13C signatures as well as a significant nonlinear negative relationship between water column ρCO2 and isotopic composition of phytoplankton, indicating a shift from diffusive uptake to active uptake by phytoplankton of CO2 or HCO3− during blooms. Calculated photosynthetic fractionation factors indicated that this shift occurs specifically when surface water CO2 drops below atmospheric equilibrium. Our results indicate that active HCO3− uptake via CCMs may be an important mechanism in maintaining phytoplankton blooms when CO2 is depleted. Further increases in anthropogenic pressure, eutrophication, and cyanobacteria blooms are therefore expected to contribute to increased bicarbonate uptake to sustain primary production.

  6. Cyanobacterial carbon concentrating mechanisms facilitate sustained CO2 depletion in eutrophic lakes

    Science.gov (United States)

    Morales-Williams, Ana M.; Wanamaker, Alan D., Jr.; Downing, John A.

    2017-06-01

    Phytoplankton blooms are increasing in frequency, intensity, and duration in aquatic ecosystems worldwide. In many eutrophic lakes, these high levels of primary productivity correspond to periods of CO2 depletion in surface waters. Cyanobacteria and other groups of phytoplankton have the ability to actively transport bicarbonate (HCO3-) across their cell membrane when CO2 concentrations are limiting, possibly giving them a competitive advantage over algae not using carbon concentrating mechanisms (CCMs). To investigate whether CCMs can maintain phytoplankton bloom biomass under CO2 depletion, we measured the δ13C signatures of dissolved inorganic carbon (δ13CDIC) and phytoplankton particulate organic carbon (δ13Cphyto) in 16 mesotrophic to hypereutrophic lakes during the ice-free season of 2012. We used mass-balance relationships to determine the dominant inorganic carbon species used by phytoplankton under CO2 stress. We found a significant positive relationship between phytoplankton biomass and phytoplankton δ13C signatures as well as a significant nonlinear negative relationship between water column ρCO2 and isotopic composition of phytoplankton, indicating a shift from diffusive uptake to active uptake by phytoplankton of CO2 or HCO3- during blooms. Calculated photosynthetic fractionation factors indicated that this shift occurs specifically when surface water CO2 drops below atmospheric equilibrium. Our results indicate that active HCO3- uptake via CCMs may be an important mechanism in maintaining phytoplankton blooms when CO2 is depleted. Further increases in anthropogenic pressure, eutrophication, and cyanobacteria blooms are therefore expected to contribute to increased bicarbonate uptake to sustain primary production.

  7. A cascade of recently discovered molecular mechanisms involved in abiotic stress tolerance of plants.

    Science.gov (United States)

    Saeed, Muhammad; Dahab, Abdel hafiz Adam; Wangzhen, Guo; Tianzhen, Zhang

    2012-04-01

    Today, agriculture is facing a tremendous threat from the climate change menace. As human survival is dependent on a constant supply of food from plants as the primary producers, we must aware of the underlying molecular mechanisms that plants have acquired as a result of molecular evolution to cope this rapidly changing environment. This understanding will help us in designing programs aimed at developing crop plant cultivars best suited to our needs of a sustainable agriculture. The field of systems biology is rapidly progressing, and new insight is coming out about the molecular mechanisms involved in abiotic stress tolerance. There is a cascade of changes in transcriptome, proteome, and metabolome of plants during these stress responses. We have tried to cover most pronounced recent developments in the field of "omics" related to abiotic stress tolerance of plants. These changes are very coordinated, and often there is crosstalk between different components of stress tolerance. The functions of various molecular entities are becoming more clear and being associated with more precise biological phenomenon.

  8. Mechanical and hypoxia stress can cause chondrocytes apoptosis through over-activation of endoplasmic reticulum stress.

    Science.gov (United States)

    Huang, Ziwei; Zhou, Min; Wang, Qian; Zhu, Mengjiao; Chen, Sheng; Li, Huang

    2017-12-01

    To examine the role of mechanical force and hypoxia on chondrocytes apoptosis and osteoarthritis (OA)-liked pathological change on mandibular cartilage through over-activation of endoplasmic reticulum stress (ERS). We used two in vitro models to examine the effect of mechanical force and hypoxia on chondrocytes apoptosis separately. The mandibular condylar chondrocytes were obtained from three-week-old male Sprague-Dawley rats. Flexcell 5000T apparatus was used to produce mechanical forces (12%, 0.5Hz, 24h vs 20%, 0.5Hz, 24h) on chondrocytes. For hypoxia experiment, the concentration of O 2 was down regulated to 5% or 1%. Cell apoptosis rates were quantified by annexin V and propidium iodide (PI) double staining and FACS analysis. Quantitative real-time PCR and western blot were performed to evaluate the activation of ERS and cellular hypoxia. Then we used a mechanical stress loading rat model to verify the involvement of ERS in OA-liked mandibular cartilage pathological change. Histological changes in mandibular condylar cartilage were assessed via hematoxylin & eosin (HE) staining. Immunohistochemistry of GRP78, GRP94, HIF-1α, and HIF-2α were performed to evaluate activation of the ERS and existence of hypoxia. Apoptotic cells were detected by the TUNEL method. Tunicamycin, 20% mechanical forces and hypoxia (1% O 2 ) all significantly increased chondrocytes apoptosis rates and expression of ERS markers (GRP78, GRP94 and Caspase 12). However, 12% mechanical forces can only increase the apoptotic sensitivity of chondrocytes. Mechanical stress resulted in OA-liked pathological change on rat mandibular condylar cartilage which included thinning cartilage and bone erosion. The number of apoptotic cells increased. ERS and hypoxia markers expressions were also enhanced. Salubrinal, an ERS inhibitor, can reverse these effects in vitro and in vivo through the down-regulation of ERS markers and hypoxia markers. We confirmed that mechanical stress and local hypoxia both

  9. Mechanism of Neonicotinoid Toxicity: Impact on Oxidative Stress and Metabolism.

    Science.gov (United States)

    Wang, Xu; Anadón, Arturo; Wu, Qinghua; Qiao, Fang; Ares, Irma; Martínez-Larrañaga, María-Rosa; Yuan, Zonghui; Martínez, María-Aránzazu

    2018-01-06

    Thousands of tons of neonicotinoids are widely used around the world as broad-spectrum systemic insecticides and veterinary drugs. Researchers originally thought that neonicotinoids exhibited low mammalian toxicity. However, following their widespread use, it became increasingly evident that neonicotinoids could have various toxic effects on vertebrates and invertebrates. The primary focus of this review is to summarize the research progress associated with oxidative stress as a plausible mechanism for neonicotinoid-induced toxicity as well as neonicotinoid metabolism. This review summarizes the research conducted over the past decade into the production of reactive oxygen species, reactive nitrogen species, and oxidative stress as aresult of neonicotinoid treatments, along with their correlation with the toxicity and metabolism of neonicotinoids. The metabolism of neonicotinoids and protection of various compounds against neonicotinoid-induced toxicity based on their antioxidative effects is also discussed. This review sheds new light on the critical roles of oxidative stress in neonicotinoid-induced toxicity to nontarget species.

  10. Physiological mechanisms through which heat stress compromises reproduction in pigs.

    Science.gov (United States)

    Ross, Jason W; Hale, Benjamin J; Seibert, Jacob T; Romoser, Matthew R; Adur, Malavika K; Keating, Aileen F; Baumgard, Lance H

    2017-09-01

    Seasonal variations in environmental temperatures impose added stress on domestic species bred for economically important production traits. These heat-mediated stressors vary on a seasonal, daily, or spatial scale, and negatively impact behavior and reduce feed intake and growth rate, which inevitably lead to reduced herd productivity. The seasonal infertility observed in domestic swine is primarily characterized by depressed reproductive performance, which manifests as delayed puberty onset, reduced farrowing rates, and extended weaning-to-estrus intervals. Understanding the effects of heat stress at the organismal, cellular, and molecular level is a prerequisite to identifying mitigation strategies that should reduce the economic burden of compromised reproduction. In this review, we discuss the effect of heat stress on an animal's ability to maintain homeostasis in multiple systems via several hypothalamic-pituitary-end organ axes. Additionally, we discuss our understanding of epigenetic programming and how hyperthermia experienced in utero influences industry-relevant postnatal phenotypes. Further, we highlight the recent recognized mechanisms by which distant tissues and organs may molecularly communicate via extracellular vesicles, a potentially novel mechanism contributing to the heat-stress response. © 2017 Wiley Periodicals, Inc.

  11. Mechanical Stress Measurement During Thin-Film Fabrication

    Science.gov (United States)

    Broadway, David M. (Inventor)

    2017-01-01

    A method and system are provided for determining mechanical stress experienced by a film during fabrication thereof on a substrate positioned in a vacuum deposition chamber. The substrate's first surface is disposed to have the film deposited thereon and the substrate's opposing second surface is a specular reflective surface. A portion of the substrate is supported. An optical displacement sensor is positioned in the vacuum deposition chamber in a spaced-apart relationship with respect to a portion of the substrate's second surface. During film deposition on the substrate's first surface, displacement of the portion of the substrate's second surface is measured using the optical displacement sensor. The measured displacement is indicative of a radius of curvature of the substrate, and the radius of curvature is indicative of mechanical stress being experienced by the film.

  12. The "footloose" mechanism: Iceberg decay from hydrostatic stresses

    Science.gov (United States)

    Wagner, Till J. W.; Wadhams, Peter; Bates, Richard; Elosegui, Pedro; Stern, Alon; Vella, Dominic; Abrahamsen, E. Povl; Crawford, Anna; Nicholls, Keith W.

    2014-08-01

    We study a mechanism of iceberg breakup that may act together with the recognized melt and wave-induced decay processes. Our proposal is based on observations from a recent field experiment on a large ice island in Baffin Bay, East Canada. We observed that successive collapses of the overburden from above an unsupported wavecut at the iceberg waterline created a submerged foot fringing the berg. The buoyancy stresses induced by such a foot may be sufficient to cause moderate-sized bergs to break off from the main berg. A mathematical model is developed to test the feasibility of this mechanism. The results suggest that once the foot reaches a critical length, the induced stresses are sufficient to cause calving. The theoretically predicted maximum stable foot length compares well to the data collected in situ. Further, the model provides analytical expressions for the previously observed "rampart-moat" iceberg surface profiles.

  13. Oxidative Stress in Disease and Aging: Mechanisms and Therapies 2016

    OpenAIRE

    Cabello-Verrugio, Claudio; Simon, Felipe; Trollet, Capucine; Santibañez, Juan F.

    2016-01-01

    International audience; Oxidative stress (OS) is an imbalance between the formation of reactive oxygen species (ROS) and antioxidant defense mechanisms. This phenomenon increases with age and affects the normal functioning of several tissues. Furthermore, numerous chronic diseases associated with older age, such as diabetes and cardiovascular, renal, pulmonary, and skeletal muscle disorders, are also directly related to OS. Considering this relationship, the aim of many ongoing studies is to ...

  14. Critical fracturing phenomenon in heterogeneous materials under external mechanical stress

    Science.gov (United States)

    Jei, Y.; Ouaskit, S.; Nassif et, R.; Boughaleb, Y.; Nechad, H.; El Guerjouma, R.

    2005-12-01

    We analyzed experiments designed for industrial applications in order to test the concept that in heterogeneous materials such as fiber composites concrete subjected to an external mechanical stress rupture is a genuine critical point. This prediction has been tested extensively on heterogeneous materials bases polymer from acoustic emission measurements. The investigating consists in simulating the two-dimensional model of a spring network. Also the bond percolation concept has been very helpful in the interpretation of the numerical results.

  15. Application of fracture mechanics to graphite under complex stress conditions

    Science.gov (United States)

    Yahr, G. T.; Valachovic, R. S.

    1974-01-01

    The purpose of this study was to examine the applicability of linear-elastic fracture mechanics to graphite under multiaxial stress conditions. The specimens were thick-walled graphite cylinders with flat heads which were internally pressurized. Two series of specimens were used. The first series had complete circumferential notches machined diagonally into the head-cylinder juncture region, while the second series was unnotched. The methods of linear-elastic fracture mechanics and a finite-element analysis were used to predict pressures to cause fracture for both notched and unnotched specimens.

  16. Chemical reactions modulated by mechanical stress: extended Bell theory.

    Science.gov (United States)

    Konda, Sai Sriharsha M; Brantley, Johnathan N; Bielawski, Christopher W; Makarov, Dmitrii E

    2011-10-28

    A number of recent studies have shown that mechanical stress can significantly lower or raise the activation barrier of a chemical reaction. Within a common approximation due to Bell [Science 200, 618 (1978)], this barrier is linearly dependent on the applied force. A simple extension of Bell's theory that includes higher order corrections in the force predicts that the force-induced change in the activation energy will be given by -FΔR - ΔχF(2)∕2. Here, ΔR is the change of the distance between the atoms, at which the force F is applied, from the reactant to the transition state, and Δχ is the corresponding change in the mechanical compliance of the molecule. Application of this formula to the electrocyclic ring-opening of cis and trans 1,2-dimethylbenzocyclobutene shows that this extension of Bell's theory essentially recovers the force dependence of the barrier, while the original Bell formula exhibits significant errors. Because the extended Bell theory avoids explicit inclusion of the mechanical stress or strain in electronic structure calculations, it allows a computationally efficient characterization of the effect of mechanical forces on chemical processes. That is, the mechanical susceptibility of any reaction pathway is described in terms of two parameters, ΔR and Δχ, both readily computable at zero force.

  17. Sustained action of developmental ethanol exposure on the cortisol response to stress in zebrafish larvae and adults.

    Science.gov (United States)

    Baiamonte, Matteo; Brennan, Caroline H; Vinson, Gavin P

    2015-01-01

    Ethanol exposure during pregnancy is one of the leading causes of preventable birth defects, leading to a range of symptoms collectively known as fetal alcohol spectrum disorder. More moderate levels of prenatal ethanol exposure lead to a range of behavioural deficits including aggression, poor social interaction, poor cognitive performance and increased likelihood of addiction in later life. Current theories suggest that adaptation in the hypothalamo-pituitary-adrenal (HPA) axis and neuroendocrine systems contributes to mood alterations underlying behavioural deficits and vulnerability to addiction. In using zebrafish (Danio rerio), the aim is to determine whether developmental ethanol exposure provokes changes in the hypothalamo-pituitary-interrenal (HPI) axis (the teleost equivalent of the HPA), as it does in mammalian models, therefore opening the possibilities of using zebrafish to elucidate the mechanisms involved, and to test novel therapeutics to alleviate deleterious symptoms. The results showed that developmental exposure to ambient ethanol, 20mM-50mM 1-9 days post fertilisation, had immediate effects on the HPI, markedly reducing the cortisol response to air exposure stress, as measured by whole body cortisol content. This effect was sustained in adults 6 months later. Morphology, growth and locomotor activity of the animals were unaffected, suggesting a specific action of ethanol on the HPI. In this respect the data are consistent with mammalian results, although they contrast with the higher corticosteroid stress response reported in rats after developmental ethanol exposure. The mechanisms that underlie the specific sensitivity of the HPI to ethanol require elucidation.

  18. Control mechanisms in the third-generation planning. Case study: Control to realize sustainable cities

    Science.gov (United States)

    Wicaksono, A. D.

    2017-06-01

    Since the last few years, Indonesia has experienced important events that bring significant changes to the social, political and economic life. The changes directly or indirectly impact the field of planning. With the challenging condition which grows fast and is more complex ahead, and the greater demands on the role of planning, it is required that planning should have higher quality. This paper seeks to answer some questions as follows: (i) How are changes in paradigm and also the development of planning model for the current transition era?, (ii) What is the best way to improve the quality of planning control on the last generation planning model to realize sustainable city?. Analysis steps that will be used to achieve the paper objectives are: (i) Review of planning and sustainable cities theory, (ii) Pattern recognition, (iii) Identifying control mechanisms and sustainable urban forms, (iv) conceptualization. Based on discussion about sustainable cities and control mechanism, some conclusions can be generated as follows: (i) The third generation planning model is based on the theory of expanded system, emphasizing on the constraint of capacity and the ability of planners within the context of larger environment, (ii) There are various theoretical studies that recommend prescriptive model or solution for sustainable urban form and structure. The concepts of Sustainable Cities can be grouped in Neotraditional Development, Urban Containment, Compact City and The Eco-City. The four models above have criteria, namely (i) high density; (ii) a high level of diversity; (iii) mixed land use; (iv) compactness; (5) sustainable transport; (6) passive solar design; (7) Greening Ecological Design. The three main activities in control mechanisms are: Monitoring and Recommendation; a comparative review of the facts (conditions that exist or are developing) with the purpose (expected conditions, set out in urban planning) and recommendations; Evaluation, a review on the

  19. Towards a new view of sustainable development: human well-being and environmental stress

    Science.gov (United States)

    Dietz, Thomas; Jorgenson, Andrew K.

    2014-03-01

    Understanding the relationship between human well-being and the stress economic activity places on the environment is a central challenge of sustainability research. Lamb et al (2014 Environ. Res. Lett. 9 014011) provide two important results that will influence future analyses. First, they show that the drivers of consumption that induce anthropogenic carbon emissions are similar to but not the same as the drivers of place-based (i.e., production driven) carbon emissions. Second, they show that a diverse set of countries are able to achieve high levels of human well-being while placing relatively little stress on the environment. Since the desire of low emission countries to increase emissions in pursuit of development is a major blockage point in international climate negotiations, the finding that emissions are decoupled from increased well-being is not only of scientific interest, it could also inform policy discussions.

  20. Does music influence stress in mechanically ventilated patients?

    Science.gov (United States)

    Chlan, Linda L; Engeland, William C; Savik, Kay

    2013-06-01

    Mechanically ventilated patients experience profound stress. Interventions are needed to ameliorate stress that does not cause adverse effects. The purpose of this study was to explore the influence of music on stress in a sample of patients over the duration of ventilatory support. Randomised controlled trial; randomised patients (56.8+16.9 years, 61% male, APACHE III 57.2+18.3) receiving ventilatory support to: (1) patient-directed music (PDM) where patients self-initiated music listening whenever desired from a preferred collection, (2) headphones only to block ICU noise, or (3) usual ICU care. Twenty-four hour urinary cortisol samples were collected from a sub-set of subjects with intact renal function and not receiving medications known to influence cortisol levels (n=65). 12 ICUs in the Midwestern United States. Urinary free cortisol (UFC), an integrative biomarker of stress. Controlling for illness severity, gender, and baseline UFC (29-45 mg/day), mixed models analysis revealed no significant differences among groups in UFC over the course of ventilatory support. While music did not significantly reduce cortisol, less profound spikes in UFC levels were observed but that, given the limitations of the research, this observation could have occurred merely by chance. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Mechanical stress as a regulator of cell motility

    Science.gov (United States)

    Putelat, T.; Recho, P.; Truskinovsky, L.

    2018-01-01

    The motility of a cell can be triggered or inhibited not only by an applied force but also by a mechanically neutral force couple. This type of loading, represented by an applied stress and commonly interpreted as either squeezing or stretching, can originate from extrinsic interaction of a cell with its neighbors. To quantify the effect of applied stresses on cell motility we use an analytically transparent one-dimensional model accounting for active myosin contraction and induced actin turnover. We show that stretching can polarize static cells and initiate cell motility while squeezing can symmetrize and arrest moving cells. We show further that sufficiently strong squeezing can lead to the loss of cell integrity. The overall behavior of the system depends on the two dimensionless parameters characterizing internal driving (chemical activity) and external loading (applied stress). We construct a phase diagram in this parameter space distinguishing between static, motile, and collapsed states. The obtained results are relevant for the mechanical understanding of contact inhibition and the epithelial-to-mesenchymal transition.

  2. Response mechanisms of Brachiaria brizantha cultivars to water deficit stress

    Directory of Open Access Journals (Sweden)

    Patricia Menezes Santos

    2013-11-01

    Full Text Available Two cultivars of Brachiaria brizantha (Hochst ex. A. Rich Stapf. (Syn. Urochloa were evaluated for their adaptation to water deficit and the stress response mechanisms in a greenhouse experiment. The experimental design was in completely randomized blocks with a 2 × 2 × 4 factorial arrangement. The Marandu and BRS Piatã cultivars were evaluated under two water availability conditions, with or without water restriction. The harvests were carried out 0, 7, 14 and 28 days after the start of water restriction. For both cultivars, the water deficit stress caused a reduction in shoot biomass and leaf area and an increase in the percentage of roots in the deeper soil layers. The B. brizantha cv. Marandu reached critical levels of leaf water potential in a shorter period of water restriction than did the B. brizantha cv. BRS Piatã. The osmoregulation and deepening of the root system are mechanisms of adaptation to water stress observed in both Marandu and BRS Piatã cultivars. Besides that, the Marandu cultivar also increases its leaf senescence and, consequentially, decreases its leaf area, as a response to water deficit.

  3. Green Concrete from Sustainable Recycled Coarse Aggregates: Mechanical and Durability Properties

    OpenAIRE

    Neeraj Jain; Mridul Garg; A. K. Minocha

    2015-01-01

    Present investigations deal with the development of green concrete (M 30 grade) using recycled coarse aggregates for sustainable development. Characterization of recycled coarse aggregates showed that physical and mechanical properties are of inferior quality and improvement in properties was observed after washing due to removal of old weak mortar adhered on its surface. The influence of natural coarse aggregates replacement (50 and 100%) with recycled coarse aggregate on various mechanical ...

  4. McKenzie treatment versus mulligan sustained natural apophyseal glides for chronic mechanical low back pain

    OpenAIRE

    Waqqar, Saira; Shakil-ur-Rehman, Syed; Ahmad, Shakeel

    2016-01-01

    Background and Objective: Chronic mechanical low back pain is common among different age groups and genders. Different manual therapy techniques combined with exercise therapy and electrotherapy modalities play an important role in its management. Our objective was to compare the effects of McKenzie extension exercisesprogram (EEP) versus Mulligan Sustained Natural Apophyseal Glides (SNAGs) for chronic mechanical low back pain (CMLBP). Methods: This randomized control trial (RCT) was conducte...

  5. Advances in functional genomics for investigating salinity stress tolerance mechanisms in cereals

    Directory of Open Access Journals (Sweden)

    Megan C Shelden

    2013-05-01

    Full Text Available Abiotic stresses such as low water availability and high salinity are major causes of cereal crop yield losses and significantly impact on sustainability. Wheat and barley are two of the most important cereal crops (after maize and rice and are grown in increasingly hostile environments with soil salinity and drought both expected to increase this century, reducing the availability of arable land. Barley and wheat are classified as glycophytes (salt-sensitive, yet they are more salt-tolerant than other cereal crops such as rice and so are good models for studying salt-tolerance in cereals. The exploitation of genetic variation of phenotypic traits through plant breeding could significantly improve growth of cereals in salinity-affected regions, thus leading to improved crop yields. Genetic variation in phenotypic traits for abiotic stress tolerance have been identified in land races and wild germplasm but the molecular basis of these differences is often difficult to determine due to the complex genetic nature of these species. High-throughput functional genomics technologies, such as transcriptomics, metabolomics, proteomics and ionomics are powerful tools for investigating the molecular responses of plants to abiotic stress. The advancement of these technologies has allowed for the identification and quantification of transcript /metabolites in specific cell types and/or tissues. Using these new technologies on plants will provide a powerful tool to uncovering genetic traits in more complex species such as wheat and barley and provide novel insights into the molecular mechanisms of salinity stress tolerance.

  6. Stress-related alterations of acyl and desacyl ghrelin circulating levels: mechanisms and functional implications

    Science.gov (United States)

    Stengel, Andreas; Wang, Lixin; Taché, Yvette

    2011-01-01

    Ghrelin is the only known peripherally produced and centrally acting peptide hormone that stimulates food intake and digestive functions. Ghrelin circulates as acylated and desacylated forms and recently the acylating enzyme, ghrelin-O-acyltransferase (GOAT) and the de-acylating enzyme, thioesterase 1/lysophospholipase 1 have been identified adding new layers of complexity to the regulation of ghrelin. Stress is known to alter gastrointestinal motility and food intake and was recently shown to modify circulating ghrelin and GOAT levels with differential responses related to the type of stressors including a reduction induced by physical stressors (abdominal surgery and immunological/endotoxin injection, exercise) and elevation by metabolic (cold exposure, fasting and caloric restriction) and psychological stressors. However, the pathways underlying the alterations of ghrelin under these various stress conditions are still largely to be defined and may relate to stress-associated autonomic changes. There is evidence that alterations of circulating ghrelin may contribute to the neuroendocrine and behavioral responses along with sustaining the energetic requirement needed upon repeated exposure to stressors. A better understanding of these mechanisms will allow targeting components of ghrelin signaling that may improve food intake and gastric motility alterations induced by stress. PMID:21782868

  7. Sustaining mechanism of small-scale turbulent eddies in a precessing sphere

    Science.gov (United States)

    Horimoto, Yasufumi; Goto, Susumu

    2017-11-01

    It has been known for a long time that fully developed turbulence is sustained in a precessing container. The aim of the present study is to reveal the sustaining mechanism of turbulence in a precessing sphere by means of laboratory experiments. We conduct experiments using a Newtonian fluid (water) and viscoelastic fluids (dilute solutions of surfactant, cetyltrimethyl ammonium chloride, and polymers, polyethylene oxide) to understand the sustaining mechanism of turbulence of Newtonian fluids by examining turbulence modifications due to the surfactant and polymer additives. When the Reynolds number based on the spin angular velocity and radius of the sphere is fixed, the most developed turbulence is sustained with the Poincaré number (the precession rate) being about 0.1. The key ingredient of the developed turbulence is a pair of large-scale vortex tubes which robustly exists in the flow. Assuming that these vortex tubes sustain small-scale turbulent eddies through an energy cascading process, we can explain all our experimental observations. Concerning the turbulence modification by the additives, the time-scale criteria by Lumley [J. Polymer Sci.: Macromol. Rev. 7, 263 (1973), 10.1002/pol.1973.230070104] and the refined theory by Tabor and de Gennes [Europhys. Lett. 2, 519 (1986), 10.1209/0295-5075/2/7/005] explain the experimental result that the pair of large-scale vortex tubes survives even when small-scale turbulent eddies are drastically suppressed by the surfactant additive.

  8. Memory-induced mechanism for self-sustaining activity in networks

    Science.gov (United States)

    Allahverdyan, A. E.; Steeg, G. Ver; Galstyan, A.

    2015-12-01

    We study a mechanism of activity sustaining on networks inspired by a well-known model of neuronal dynamics. Our primary focus is the emergence of self-sustaining collective activity patterns, where no single node can stay active by itself, but the activity provided initially is sustained within the collective of interacting agents. In contrast to existing models of self-sustaining activity that are caused by (long) loops present in the network, here we focus on treelike structures and examine activation mechanisms that are due to temporal memory of the nodes. This approach is motivated by applications in social media, where long network loops are rare or absent. Our results suggest that under a weak behavioral noise, the nodes robustly split into several clusters, with partial synchronization of nodes within each cluster. We also study the randomly weighted version of the models where the nodes are allowed to change their connection strength (this can model attention redistribution) and show that it does facilitate the self-sustained activity.

  9. Stiffness-Controlled Thermoresponsive Hydrogels for Cell Harvesting with Sustained Mechanical Memory.

    Science.gov (United States)

    Fan, Xingliang; Zhu, Lu; Wang, Ke; Wang, Bingjie; Wu, Yaozu; Xie, Wei; Huang, Chengyu; Chan, Barbara Pui; Du, Yanan

    2017-03-01

    Most mechanobiological investigations focused on in situ mechanical regulation of cells on stiffness-controlled substrates with few downstream applications, as it is still challenging to harvest and expand mechanically primed cells by enzymatic digestion (e.g., trypsin) without interrupting cellular mechanical memory between passages. This study develops thermoresponsive hydrogels with controllable stiffness to generate mechanically primed cells with intact mechanical memory for augmented wound healing. No significant cellular property alteration of the fibroblasts primed on thermoresponsive hydrogels with varied stiffness has been observed through thermoresponsive harvesting. When reseeding the harvested cells for further evaluation, softer hydrogels are proven to better sustain the mechanical priming effects compared to rigid tissue culture plate, which indicates that both the stiffness-controlled substrate and thermoresponsive harvesting are required to sustain cellular mechanical memory between passages. Moreover, epigenetics analysis reveals that thermoresponsive harvesting could reduce the rearrangement and loss of chromatin proteins compared to that of trypsinization. In vivo wound healing using mechanically primed fibroblasts shows featured epithelium and sebaceous glands, which indicates augmented skin recovery compared with trypsinized fibroblasts. Thus, the thermoresponsive hydrogel-based cell harvesting system offers a powerful tool to investigate mechanobiology between cell passages and produces abundant cells with tailored mechanical priming properties for cell-based applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. MANAGING SUSTAINABLE DEVELOPMENT OF MEAT PROCESSING PLANTS AS PART OF THE MECHANISM OF STRATEGIC PLANNING

    Directory of Open Access Journals (Sweden)

    I. S. Gusev

    2015-01-01

    Full Text Available Studies have proven that, at present one of the priority research areas as part of the Development Strategy of the Food Processing Industry of the Russian Federation until 2020 is to develop effective mechanisms for sustainable socio-economic development of industrial enterprises. This article investigated the logic of strategic planning within the framework of sustainable economic growth, analyzed the structure of strategic planning, study the subject of strategic planning in the management of sustainable development of enterprises, justified the basic principles of strategic planning for the effective management of sustainable development of industrial enterprises, as well as the complex of organizational tactical activities of operational management strategy for sustainable development of the enterprise. The observation revealed that currently there was a high need for the framework of the branch, departmental and state programs implemented in industrial management of scientific and methodological approaches of strategic planning. Studies have shown that these approaches in its conceptual entity should be based on the growth potential of the sustainable development of meat processing plants in space and time in order to achieve high competitive advantages. Conducted a systematic analysis of industry conditions proved that the problem of sustainable operation and development of meat processing enterprises as a problem of management and control is relatively new, unexplored and highly relevant. On the contrary, it is the basis of modern management strategy and management is a concept and methodology of the so-called adaptive enterprise development under the action of various external and internal factors, risks that may threaten its economic stability and sustainability.

  11. Hindered dissolution of fibrin formed under mechanical stress.

    Science.gov (United States)

    Varjú, I; Sótonyi, P; Machovich, R; Szabó, L; Tenekedjiev, K; Silva, M M C G; Longstaff, C; Kolev, K

    2011-05-01

    Recent data indicate that stretching forces cause a dramatic decrease in clot volume accompanied by gross conformational changes of fibrin structure. The present study attempts to characterize the lytic susceptibility of fibrin exposed to mechanical stress as a model for fibrin structures observed in vivo. The relevance of stretched fibrin models was substantiated by scanning electron microscopic (SEM) evaluation of human thrombi removed during surgery, where surface fibrin fibers were observed to be oriented in the direction of shear forces, whereas interior fibers formed a random spatial meshwork. These structural variations were modeled in vitro with fibrin exposed to adjustable mechanical stress. After two- and three-fold longitudinal stretching (2 × S, 3 × S) the median fiber diameter and pore area in SEM images of fibrin decreased two- to three-fold. Application of tissue plasminogen activator (tPA) to the surface of model clots, which contained plasminogen, resulted in plasmin generation which was measured in the fluid phase. After 30-min activation 12.6 ± 0.46 pmol mm(-2) plasmin was released from the non-stretched clot (NS), 5.5 ± 1.11 pmol mm(-2) from 2 × S and 2.3 ± 0.36 pmol mm(-2) from 3 × S clot and this hampered plasmin generation was accompanied by decreased release of fibrin degradation products from stretched fibrins. Confocal microscopic images showed that a green fluorescent protein-fusion variant of tPA accumulated in the superficial layer of NS, but not in stretched fibrin. Mechanical stress confers proteolytic resistance to fibrin, which is a result of impaired plasminogen activation coupled to lower plasmin sensitivity of the denser fibrin network. © 2011 International Society on Thrombosis and Haemostasis.

  12. Loss of Sustained Activity in the Ventromedial Prefrontal Cortex in Response to Repeated Stress in Individuals with Early-Life Emotional Abuse: Implications for Depression Vulnerability

    Directory of Open Access Journals (Sweden)

    Lihong eWang

    2013-06-01

    Full Text Available Repeated psychosocial stress in early life has significant impact on both behavior and neural function which, together, increase vulnerability to depression. However, neural mechanisms related to repeated stress remain unclear. We hypothesize that early-life stress may result in a reduced capacity for cognitive control in response to a repeated stressor, particularly in individuals who developed maladaptive emotional processing strategies, namely trait rumination. Individuals who encountered early-life stress but have adaptive emotional processing, namely trait mindfulness, may demonstrate an opposite pattern. Using a mental arithmetic task to induce mild stress and a mindful breathing task to induce a mindful state, we tested this hypothesis by examining blood perfusion changes over time in healthy young men. We found that subjects with early-life stress, particularly emotional abuse, failed to sustain neural activation in the orbitofrontal and ventromedial prefrontal cortex (vmPFC over time. Given that the vmPFC is known to regulate amygdala activity during emotional processing, we subsequently compared the perfusion in the vmPFC and the amygdala in depression-vulnerable (having early life stress and high in rumination and resilient (having early life stress and high in mindfulness subjects. We found that depression-vulnerable subjects had increased amygdala perfusion and reduced vmPFC perfusion during the later runs than that during the earlier stressful task runs. In contrast, depression resilient individuals showed the reverse pattern. Our results indicate that the vmPFC of depression-vulnerable subjects may have a limited capacity to inhibit amygdala activation to repeated stress over time, whereas the vmPFC in resilient individuals may adapt to stress quickly. This pilot study warrants future investigation to clarify the stress-related neural activity pattern dynamically to identify depression vulnerability at an individual level.

  13. The clean development mechanism's contribution to sustainable development: A review of the literature

    DEFF Research Database (Denmark)

    Olsen, Karen Holm

    2007-01-01

    The challenges of how to respond to climate change and ensure sustainable development are currently high on the political agenda among the world's leading nations. The Clean Development Mechanism (CDM) is part of the global carbon market developing rapidly as part of the Kyoto response towards...... the mitigation of global warming. One of the aims of the CDM is to achieve sustainable development in developing countries, but uncertainty prevails as to whether the CDM is doing what it promises to do. Close to 200 studies on the CDM have been carried out since its birth in 1997 including peer...

  14. Adhesive fracture mechanics. [stress analysis for bond line interface

    Science.gov (United States)

    Bennett, S. J.; Devries, K. L.; Williams, M. L.

    1974-01-01

    In studies of fracture mechanics the adhesive fracture energy is regarded as a fundamental property of the adhesive system. It is pointed out that the value of the adhesive fracture energy depends on surface preparation, curing conditions, and absorbed monolayers. A test method reported makes use of a disk whose peripheral part is bonded to a substrate material. Pressure is injected into the unbonded central part of the disk. At a certain critical pressure value adhesive failure can be observed. A numerical stress analysis involving arbitrary geometries is conducted.

  15. Stress begets stress: Three studies of the daily behavioral and affective mechanisms of spillover

    OpenAIRE

    Sears, Meredith

    2015-01-01

    The studies that make up this dissertation adopt process-oriented approaches to examine the mechanisms by which daily stressors result in disruptions to interpersonal relationships. To do so, all three studies made use of daily diaries or momentary survey assessment techniques to measure changes in stressors, cognition, behavior and affect across multiple time points. Each study also examined individual- and couple-level factors that were hypothesized to affect recovery from stressful events....

  16. Mechanics of Intracellular Stress Fibers: A Short Review

    Science.gov (United States)

    Ikai, Atsushi; Watanabe-Nakayama, Takahiro; Machida, Shinichi; Saito, Masakazu; Afrin, Rehana

    2011-08-01

    The mechanical response of living cells against external stimuli depends largely on the physical and biochemical properties of an intracellular structure called cytoskeleton. Three main kinds of filamentous protein structures, namely, microtubules, intermediate filaments, and actin thin filaments comprise the cytoskeleton. In the case of cells cultured on an adhesive substrate, the development of actin-based cytoskeleton, especially linearly bundled actin filaments called stress fibers (SFs), is well established. SFs are formed close to the cell membrane with one or both of their ends associated with the transmembrane structure called the focal adhesion (FA). In this article, we review some fundamental facts about SFs in live cells starting from the early description of the bundled filaments as observed under optical and electron microscopies. The morphology, chemical components, and biological functions of SFs, and recent work on the mechanical nature of SFs are reviewed.

  17. Can the Clean Development Mechanism attain both cost-effectiveness and sustainable development objectives?

    Energy Technology Data Exchange (ETDEWEB)

    Kolshus, Hans H; Vevatne, Jonas; Torvanger, Asbjoern; Aunan, Kristin

    2001-06-01

    The Clean Development Mechanism (CDM), as defined in the Kyoto Protocol, has two objectives: to promote sustainable development in host developing countries, and to improve global cost-effectiveness by assisting developed countries in meeting their Kyoto targets. The aim of this paper is to explore the background of the CDM and discuss to what extent its current design allows it to achieve its dual objective. The first part of the paper is a literature review that includes descriptions of the flexibility mechanisms under the Kyoto Protocol; the CDM's market potential, and the issues of cost-effectiveness and sustainable development. In the second part of the paper, we discuss to what extent there is a conflict between cost-effectiveness and sustain ability, and whether the two objectives of the CDM can be achieved simultaneously. We develop a set of indicators to evaluate non-carbon benefits of CDM projects on the environment, development, and. equity, and show how these indicators can be used in practice by looking at case studies of CDM project candidates in the energy sector from Brazil and China. We demonstrate that for some CDM projects there is a trade-off between cost-effectiveness, in terms of a low quota price, and a high score on sustain ability indicators. We have reason to believe that the size of the CDM market in some studies is over-estimated since transaction costs and the challenge of promoting sustainable development are not fully accounted for. Also, we find that the proposed set of indicators can be a necessary tool to assure that sustain ability impacts of CDM projects are taken into consideration. (author)

  18. Built-In Mechanical Stress in Viral Shells

    Science.gov (United States)

    Carrasco, C.; Luque, A.; Hernando-Pérez, M.; Miranda, R.; Carrascosa, J.L.; Serena, P.A.; de Ridder, M.; Raman, A.; Gómez-Herrero, J.; Schaap, I.A.T.; Reguera, D.; de Pablo, P.J.

    2011-01-01

    Mechanical properties of biological molecular aggregates are essential to their function. A remarkable example are double-stranded DNA viruses such as the ϕ29 bacteriophage, that not only has to withstand pressures of tens of atmospheres exerted by the confined DNA, but also uses this stored elastic energy during DNA translocation into the host. Here we show that empty prolated ϕ29 bacteriophage proheads exhibit an intriguing anisotropic stiffness which behaves counterintuitively different from standard continuum elasticity predictions. By using atomic force microscopy, we find that the ϕ29 shells are approximately two-times stiffer along the short than along the long axis. This result can be attributed to the existence of a residual stress, a hypothesis that we confirm by coarse-grained simulations. This built-in stress of the virus prohead could be a strategy to provide extra mechanical strength to withstand the DNA compaction during and after packing and a variety of extracellular conditions, such as osmotic shocks or dehydration. PMID:21320456

  19. The 'footloose' mechanism: Iceberg decay from hydrostatic stresses

    Science.gov (United States)

    Wagner, T. J. W.; Wadhams, P.; Bates, C. R.; Elosegui, P.; Stern, A. A.; Vella, D.; Abrahamsen, E. P.; Crawford, A. J.; Nicholls, K. W.

    2014-12-01

    We study a mechanism of iceberg breakup that may act together with the recognized melt and wave-induced decay processes. Our proposal is based on observations from a recent field experiment on a large ice island in Baffin Bay, East Canada. We observed that successive collapses of the overburden from above an unsupported wavecut at the iceberg waterline created a submerged foot fringing the berg. The buoyancy stresses induced by such a foot may be sufficient to cause moderate-sized bergs to break off from the main berg. A mathematical model is developed to test the feasibility of this mechanism. The results suggest that once the foot reaches a critical length, the induced stresses are sufficient to cause calving. The theoretically predicted maximum stable foot length compares well to the data collected in situ. Further, the model provides analytical expressions for the previously observed 'rampart-moat' iceberg surface profiles. Finally, we comment on the implications for the calving of icebergs from shelf fronts, where similar underwater 'feet' have been observed.

  20. Responses to combined abiotic and biotic stress in tomato are governed by stress intensity and resistance mechanism

    NARCIS (Netherlands)

    Kissoudis, Christos; Sri Sunarti, Sri; De Wiel, Van Clemens; Visser, Richard G.F.; Linden, van der Gerard; Bai, Yuling

    2016-01-01

    Stress conditions in agricultural ecosystems can occur at variable intensities. Different resistance mechanisms against abiotic stress and pathogens are deployed by plants. Thus, it is important to examine plant responses to stress combinations under different scenarios. Here, we evaluated the

  1. Supplementary data: Responses to combined abiotic and biotic stress in tomato are governed by stress intensity and mechanism of resistance

    NARCIS (Netherlands)

    Kissoudis, C.; Sri Sunarti, Sri; Wiel, van de C.C.M.; Visser, R.G.F.; Linden, van der C.G.; Bai, Y.

    2016-01-01

    Stress conditions in agricultural ecosystems can occur in variable intensities. Different resistance mechanisms to abiotic stress and pathogens are deployed by plants. Thus, it is important to examine plant responses to stress combinations under different scenarios. Here, we evaluated the effect of

  2. Molecular Mechanisms behind Free Radical Scavengers Function against Oxidative Stress.

    Science.gov (United States)

    Ahmadinejad, Fereshteh; Geir Møller, Simon; Hashemzadeh-Chaleshtori, Morteza; Bidkhori, Gholamreza; Jami, Mohammad-Saeid

    2017-07-10

    Accumulating evidence shows that oxidative stress is involved in a wide variety of human diseases: rheumatoid arthritis, Alzheimer's disease, Parkinson's disease, cancers, etc. Here, we discuss the significance of oxidative conditions in different disease, with the focus on neurodegenerative disease including Parkinson's disease, which is mainly caused by oxidative stress. Reactive oxygen and nitrogen species (ROS and RNS, respectively), collectively known as RONS, are produced by cellular enzymes such as myeloperoxidase, NADPH-oxidase (nicotinamide adenine dinucleotide phosphate-oxidase) and nitric oxide synthase (NOS). Natural antioxidant systems are categorized into enzymatic and non-enzymatic antioxidant groups. The former includes a number of enzymes such as catalase and glutathione peroxidase, while the latter contains a number of antioxidants acquired from dietary sources including vitamin C, carotenoids, flavonoids and polyphenols. There are also scavengers used for therapeutic purposes, such as 3,4-dihydroxyphenylalanine (L-DOPA) used routinely in the treatment of Parkinson's disease (not as a free radical scavenger), and 3-methyl-1-phenyl-2-pyrazolin-5-one (Edaravone) that acts as a free radical detoxifier frequently used in acute ischemic stroke. The cell surviving properties of L-DOPA and Edaravone against oxidative stress conditions rely on the alteration of a number of stress proteins such as Annexin A1, Peroxiredoxin-6 and PARK7/DJ-1 (Parkinson disease protein 7, also known as Protein deglycase DJ-1). Although they share the targets in reversing the cytotoxic effects of H₂O₂, they seem to have distinct mechanism of function. Exposure to L-DOPA may result in hypoxia condition and further induction of ORP150 (150-kDa oxygen-regulated protein) with its concomitant cytoprotective effects but Edaravone seems to protect cells via direct induction of Peroxiredoxin-2 and inhibition of apoptosis.

  3. Molecular Mechanisms behind Free Radical Scavengers Function against Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Fereshteh Ahmadinejad

    2017-07-01

    Full Text Available Accumulating evidence shows that oxidative stress is involved in a wide variety of human diseases: rheumatoid arthritis, Alzheimer’s disease, Parkinson’s disease, cancers, etc. Here, we discuss the significance of oxidative conditions in different disease, with the focus on neurodegenerative disease including Parkinson’s disease, which is mainly caused by oxidative stress. Reactive oxygen and nitrogen species (ROS and RNS, respectively, collectively known as RONS, are produced by cellular enzymes such as myeloperoxidase, NADPH-oxidase (nicotinamide adenine dinucleotide phosphate-oxidase and nitric oxide synthase (NOS. Natural antioxidant systems are categorized into enzymatic and non-enzymatic antioxidant groups. The former includes a number of enzymes such as catalase and glutathione peroxidase, while the latter contains a number of antioxidants acquired from dietary sources including vitamin C, carotenoids, flavonoids and polyphenols. There are also scavengers used for therapeutic purposes, such as 3,4-dihydroxyphenylalanine (L-DOPA used routinely in the treatment of Parkinson’s disease (not as a free radical scavenger, and 3-methyl-1-phenyl-2-pyrazolin-5-one (Edaravone that acts as a free radical detoxifier frequently used in acute ischemic stroke. The cell surviving properties of L-DOPA and Edaravone against oxidative stress conditions rely on the alteration of a number of stress proteins such as Annexin A1, Peroxiredoxin-6 and PARK7/DJ-1 (Parkinson disease protein 7, also known as Protein deglycase DJ-1. Although they share the targets in reversing the cytotoxic effects of H2O2, they seem to have distinct mechanism of function. Exposure to L-DOPA may result in hypoxia condition and further induction of ORP150 (150-kDa oxygen-regulated protein with its concomitant cytoprotective effects but Edaravone seems to protect cells via direct induction of Peroxiredoxin-2 and inhibition of apoptosis.

  4. Design of sustained release fine particles using two-step mechanical powder processing: particle shape modification of drug crystals and dry particle coating with polymer nanoparticle agglomerate.

    Science.gov (United States)

    Kondo, Keita; Ito, Natsuki; Niwa, Toshiyuki; Danjo, Kazumi

    2013-09-10

    We attempted to prepare sustained release fine particles using a two-step mechanical powder processing method; particle-shape modification and dry particle coating. First, particle shape of bulk drug was modified by mechanical treatment to yield drug crystals suitable for the coating process. Drug crystals became more rounded with increasing rotation speed, which demonstrates that powerful mechanical stress yields spherical drug crystals with narrow size distribution. This process is the result of destruction, granulation and refinement of drug crystals. Second, the modified drug particles and polymer coating powder were mechanically treated to prepare composite particles. Polymer nanoparticle agglomerate obtained by drying poly(meth)acrylate aqueous dispersion was used as a coating powder. The porous nanoparticle agglomerate has superior coating performance, because it is completely deagglomerated under mechanical stress to form fine fragments that act as guest particles. As a result, spherical drug crystals treated with porous agglomerate were effectively coated by poly(meth)acrylate powder, showing sustained release after curing. From these findings, particle-shape modification of drug crystals and dry particle coating with nanoparticle agglomerate using a mechanical powder processor is expected as an innovative technique for preparing controlled-release coated particles having high drug content and size smaller than 100 μm. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Understanding water deficit stress-induced changes in the basic metabolism of higher plants - biotechnologically and sustainably improving agriculture and the ecoenvironment in arid regions of the globe.

    Science.gov (United States)

    Shao, Hong-Bo; Chu, Li-Ye; Jaleel, C Abdul; Manivannan, P; Panneerselvam, R; Shao, Ming-An

    2009-01-01

    Water is vital for plant growth, development and productivity. Permanent or temporary water deficit stress limits the growth and distribution of natural and artificial vegetation and the performance of cultivated plants (crops) more than any other environmental factor. Productive and sustainable agriculture necessitates growing plants (crops) in arid and semiarid regions with less input of precious resources such as fresh water. For a better understanding and rapid improvement of soil-water stress tolerance in these regions, especially in the water-wind eroded crossing region, it is very important to link physiological and biochemical studies to molecular work in genetically tractable model plants and important native plants, and further extending them to practical ecological restoration and efficient crop production. Although basic studies and practices aimed at improving soil water stress resistance and plant water use efficiency have been carried out for many years, the mechanisms involved at different scales are still not clear. Further understanding and manipulating soil-plant water relationships and soil-water stress tolerance at the scales of ecology, physiology and molecular biology can significantly improve plant productivity and environmental quality. Currently, post-genomics and metabolomics are very important in exploring anti-drought gene resources in various life forms, but modern agriculturally sustainable development must be combined with plant physiological measures in the field, on the basis of which post-genomics and metabolomics have further practical prospects. In this review, we discuss physiological and molecular insights and effects in basic plant metabolism, drought tolerance strategies under drought conditions in higher plants for sustainable agriculture and ecoenvironments in arid and semiarid areas of the world. We conclude that biological measures are the bases for the solutions to the issues relating to the different types of

  6. Mechanical-tactile stimulation (MTS) during neonatal stress prevents hyperinsulinemia despite stress-induced adiposity in weanling rat pups

    OpenAIRE

    Moyer-Mileur, Laurie J.; Haley, Shannon; Gulliver, Kristina; Thomson, Anne; Slater, Hillarie; Barrett, Brett; Joss-Moore, Lisa A; Callaway, Christopher; McKnight, Robert A.; Moore, Barry; Lane, Robert H.

    2011-01-01

    Stress in early life negatively influences growth quality through perturbations in body composition including increased fat mass. At term (40 weeks) preterm infants have greater fat mass and abdominal visceral adipose tissue than term-born infants. Mechanical-tactile stimulation (MTS) attenuates the stress response in preterm infants and rodents. We tested the hypothesis that MTS, administered during an established model of neonatal stress, would decrease stress-driven adiposity and prevent a...

  7. On the initiation of sustained slip-weakening ruptures by localized stresses

    KAUST Repository

    Galis, Martin

    2014-12-10

    Numerical simulations of dynamic earthquake rupture require an artificial initiation procedure, if they are not integrated in long-term earthquake cycle simulations. A widely applied procedure involves an \\'overstressed asperity\\', a localized region stressed beyond the static frictional strength. The physical properties of the asperity (size, shape and overstress) may significantly impact rupture propagation. In particular, to induce a sustained rupture the asperity size needs to exceed a critical value. Although criteria for estimating the critical nucleation size under linear slip-weakening friction have been proposed for 2-D and 3-D problems based on simplifying assumptions, they do not provide general rules for designing 3-D numerical simulations. We conduct a parametric study to estimate parameters of the asperity that minimize numerical artefacts (e.g. changes of rupture shape and speed, artificial supershear transition, higher slip-rate amplitudes). We examine the critical size of square, circular and elliptical asperities as a function of asperity overstress and background (off-asperity) stress. For a given overstress, we find that asperity area controls rupture initiation while asperity shape is of lesser importance. The critical area obtained from our numerical results contrasts with published theoretical estimates when background stress is low. Therefore, we derive two new theoretical estimates of the critical size under low background stress while also accounting for overstress. Our numerical results suggest that setting the asperity overstress and area close to their critical values eliminates strong numerical artefacts even when the overstress is large. We also find that properly chosen asperity size or overstress may significantly shorten the duration of the initiation. Overall, our results provide guidelines for determining the size of the asperity and overstress to minimize the effects of the forced initiation on the subsequent spontaneous

  8. Promoting sustainable development or legitimising free trade? Civil society mechanisms in EU trade agreements

    OpenAIRE

    Orbie, Jan; Martens, Deborah; Oehri, Myriam; Van Den Putte, Lore

    2017-01-01

    This study critically reflects on the involvement of civil society actors in the sustainable development chapters of recent EU trade agreements. It discusses how civil society mechanisms may legitimise the underlying neoliberal orientation of the agreements through co-optation of critical actors. Starting from a critical perspective and drawing on evidence from innovative survey data, qualitative interviews and participatory observations, it concludes that, despite overall criticism, there is...

  9. Regional mechanical properties and stress analysis of the human anterior lens capsule.

    Science.gov (United States)

    Pedrigi, R M; David, G; Dziezyc, J; Humphrey, J D

    2007-06-01

    The lens capsule of the eye functions, in part, as a deformable support through which the ciliary body applies tractions that can alter lens curvature and corresponding refractive power during the process of accommodation. Although it has long been recognized that characterization of the mechanical properties of the lens capsule is fundamental to understanding this physiologic process as well as clinical interventions, prior data have been limited by one-dimensional testing of excised specimens despite the existence of multiaxial loading in vivo. In this paper, we employ a novel experimental approach to study in situ the regional, multiaxial mechanical behavior of both normal and diabetic human anterior lens capsules. Furthermore, we use these data to calculate material parameters in a nonlinear stress-strain relation via a custom sub-domain inverse finite element method (FEM). These parameters are then used to predict capsular stresses in response to imposed loads using a forward FEM model. Our results for both normal and diabetic human eyes show that the anterior lens capsule exhibits a nonlinear pseudoelastic behavior over finite strains that is typical of soft tissues, and that strains are principal relative to meridional and circumferential directions. Experimental data and parameter estimation suggest further that the capsule is regionally anisotropic, with the circumferential direction becoming increasingly stiffer than the meridional direction towards the equator. Although both normal and diabetic lens capsules exhibited these general characteristic behaviors, diabetic capsules were significantly stiffer at each distension. Finally, the forward FEM model predicted a nearly uniform, equibiaxial stress field during normalcy that will be perturbed by cataract surgery. Such mechanical perturbations may be an underlying modulator of the sustained errant epithelial cell behavior that is observed well after cataract surgery and may ultimately contribute to

  10. Damage of rat liver tissue caused by repeated and sustained +Gz exposure and the mechanism thereof

    Directory of Open Access Journals (Sweden)

    Wen-bing LI

    2014-03-01

    Full Text Available Objective  To explore the mechanisms of positive acceleration (+Gz on the damage of rat liver tissue and the effect of +Gz on the expression of JNK/c-Jun in liver cells. Methods  Twenty four male Wistar rats were randomly divided into 4 groups (n=6: control, +2Gz, +6Gz and +10Gz group. With prone position, the rats in control group were fixed to the turning arm of centrifuge with head towards the axis for 5 minutes. The fixation method in +2Gz, +6Gz and +10Gz group was the same as in the control group. The increase rate of acceleration was 1G/s with a peak-time of 3 minutes, and each +Gz exposure repeated 5 times with an interval of 30 minutes. HE staining was used to observe the morphological changes of liver tissue, fluorescence real-time quantitative PCR to detect the expression of hepatic c-Jun mRNA, and Western blotting to detect the hepatic protein expression of p-c-Jun, c-Jun, p-JNK and JNK. Plasma aspartate aminotransferase (AST and alanine aminotransferase (ALT were determined. Results  The levels of serum ALT and AST increased significantly in +6Gz and, especially, the +10Gz group than in control group and +2Gz group (P<0.05. The same situation also existed in the increase of c-Jun mRNA expression (P<0.05. Hepatic c-jun and p-c-Jun (c-Jun activated form protein expression increased with the increase of G value. Compared with control group, no change was found in JNK protein expression in the other three groups, but the expression of p-JNK (activated form of JNK increased in +6Gz and +10Gz groups (P<0.05. HE staining showed the disorganized liver cells with irregular shapes, the unclear cell gap and the vacuolar changes in +6Gz and +10Gz groups. Conclusions  Repeated and sustained +Gz may cause enhanced expression of c-Jun/ p-c-Jun and p-JNK in hepatic cells. JNK/c-Jun signaling pathway may play an important role in the process of hepatic stress injury. DOI: 10.11855/j.issn.0577-7402.2014.03.15

  11. A test to assess the mechanical power sustainable during everyday activities in older people.

    Science.gov (United States)

    Capodaglio, Edda Maria; Saibene, Franco

    2003-01-01

    to define with a simple test the power sustainable by older people during everyday occupations. nine healthy subjects (65-71 years) performed two series of 5-6 trials on bicycle and arm ergometers at constant power. Throughout the exercise they reported their evaluation of the effort, referred either to perceived whole body exertion or to the working muscles, using Borg's category-ratio, CR10, scale. The exercise was interrupted when CR7 was attained. From a linear regression of the individual data of the work done from the start of each trial to the transition from CR4 to CR5, corresponding to 'somewhat heavy' and 'heavy', and the corresponding duration it was possible to calculate the slope of the work/time relationship. This was considered as the value of power sustainable for leg or arm muscles. on average the sustainable power for the work done on the bicycle ergometer represented 55% of the maximal mechanical power. During the control trial on the bicycle ergometer at a power corresponding to their sustainable power the subjects were able to exercise for 30 min without symptoms of fatigue or discomfort, with an average CR of 3. The average heart rate was 114 bpm and the blood lactate concentration at the end of the exercise was always lower than 4 mmol/l. Sustainable power calculated for the arm muscles was about one quarter that of the leg muscles, but all subjects reported the evaluation of the effort as more difficult. the determination of power sustainable for the leg muscles with this simple test appears reliable and accurate.

  12. Sustained action of developmental ethanol exposure on the cortisol response to stress in zebrafish larvae and adults.

    Directory of Open Access Journals (Sweden)

    Matteo Baiamonte

    Full Text Available Ethanol exposure during pregnancy is one of the leading causes of preventable birth defects, leading to a range of symptoms collectively known as fetal alcohol spectrum disorder. More moderate levels of prenatal ethanol exposure lead to a range of behavioural deficits including aggression, poor social interaction, poor cognitive performance and increased likelihood of addiction in later life. Current theories suggest that adaptation in the hypothalamo-pituitary-adrenal (HPA axis and neuroendocrine systems contributes to mood alterations underlying behavioural deficits and vulnerability to addiction. In using zebrafish (Danio rerio, the aim is to determine whether developmental ethanol exposure provokes changes in the hypothalamo-pituitary-interrenal (HPI axis (the teleost equivalent of the HPA, as it does in mammalian models, therefore opening the possibilities of using zebrafish to elucidate the mechanisms involved, and to test novel therapeutics to alleviate deleterious symptoms.The results showed that developmental exposure to ambient ethanol, 20mM-50mM 1-9 days post fertilisation, had immediate effects on the HPI, markedly reducing the cortisol response to air exposure stress, as measured by whole body cortisol content. This effect was sustained in adults 6 months later. Morphology, growth and locomotor activity of the animals were unaffected, suggesting a specific action of ethanol on the HPI. In this respect the data are consistent with mammalian results, although they contrast with the higher corticosteroid stress response reported in rats after developmental ethanol exposure. The mechanisms that underlie the specific sensitivity of the HPI to ethanol require elucidation.

  13. Mechanically tuned nanocomposite coating on titanium metal with integrated properties of biofilm inhibition, cell proliferation, and sustained drug delivery.

    Science.gov (United States)

    Mishra, Sandeep K; Teotia, Arun K; Kumar, Ashok; Kannan, Sanjeevi

    2017-01-01

    The clinical success of coated implants in executing biological functions inclusive of sustainable drug release and long term antibacterial activity without antibiotics is critical. To this aim, a nanohybrid of silver nanoparticles (AgNPs) cored in polyvinyl alcohol nanocapsules (Ag-PVA NCs) embedded in chitosan (CS) matrix loaded with anti-inflammatory drug naproxen was prepared. The synthesized nanohybrids that were subjected to coatings on (3-aminopropyl)triethoxysilane (APTES) treated titanium (Ti) metal exhibited dual role of excellent inhibition on biofilm formation and sustained drug release. These dual characteristics are achieved mainly based on intrinsic antibacterial property of AgNPs and differential entrapment of drug in PVA polymeric shell of AgNPs and CS matrix. The coatings also demonstrated enhanced mechanical properties with increasing inorganic filler and stress shielding on Ti metal. The biocompatibility tests involving adhesion, proliferation and differentiation of osteoblast cells demonstrated the efficacy of Ag-PVA NCs embedded in CS matrix as a suitable coating material for orthopedic applications. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Spatio-temporal Dynamics and Mechanisms of Stress Granule Assembly.

    Directory of Open Access Journals (Sweden)

    Daisuke Ohshima

    2015-06-01

    Full Text Available Stress granules (SGs are non-membranous cytoplasmic aggregates of mRNAs and related proteins, assembled in response to environmental stresses such as heat shock, hypoxia, endoplasmic reticulum (ER stress, chemicals (e.g. arsenite, and viral infections. SGs are hypothesized as a loci of mRNA triage and/or maintenance of proper translation capacity ratio to the pool of mRNAs. In brain ischemia, hippocampal CA3 neurons, which are resilient to ischemia, assemble SGs. In contrast, CA1 neurons, which are vulnerable to ischemia, do not assemble SGs. These results suggest a critical role SG plays in regards to cell fate decisions. Thus SG assembly along with its dynamics should determine the cell fate. However, the process that exactly determines the SG assembly dynamics is largely unknown. In this paper, analyses of experimental data and computer simulations were used to approach this problem. SGs were assembled as a result of applying arsenite to HeLa cells. The number of SGs increased after a short latent period, reached a maximum, then decreased during the application of arsenite. At the same time, the size of SGs grew larger and became localized at the perinuclear region. A minimal mathematical model was constructed, and stochastic simulations were run to test the modeling. Since SGs are discrete entities as there are only several tens of them in a cell, commonly used deterministic simulations could not be employed. The stochastic simulations replicated observed dynamics of SG assembly. In addition, these stochastic simulations predicted a gamma distribution relative to the size of SGs. This same distribution was also found in our experimental data suggesting the existence of multiple fusion steps in the SG assembly. Furthermore, we found that the initial steps in the SG assembly process and microtubules were critical to the dynamics. Thus our experiments and stochastic simulations presented a possible mechanism regulating SG assembly.

  15. Stress relaxation insensitive designs for metal compliant mechanism threshold accelerometers

    Directory of Open Access Journals (Sweden)

    Carlos Vilorio

    2015-12-01

    Full Text Available We present two designs for metal compliant mechanisms for use as threshold accelerometers which require zero external power. Both designs rely on long, thin flexures positioned orthogonally to a flat body. The first design involves cutting or stamping a thin spring-steel sheet and then bending elements to form the necessary thin flexors. The second design uses precut spring-steel flexure elements mounted into a mold which is then filled with molten tin to form a bimetallic device. Accelerations necessary to switch the devices between bistable states were measured using a centrifuge. Both designs showed very little variation in threshold acceleration due to stress relaxation over a period of several weeks. Relatively large variations in threshold acceleration were observed for devices of the same design, most likely due to variations in the angle of the flexor elements relative to the main body of the devices.

  16. DNA replication stress: from molecular mechanisms to human disease.

    Science.gov (United States)

    Muñoz, Sergio; Méndez, Juan

    2017-02-01

    The genome of proliferating cells must be precisely duplicated in each cell division cycle. Chromosomal replication entails risks such as the possibility of introducing breaks and/or mutations in the genome. Hence, DNA replication requires the coordinated action of multiple proteins and regulatory factors, whose deregulation causes severe developmental diseases and predisposes to cancer. In recent years, the concept of "replicative stress" (RS) has attracted much attention as it impinges directly on genomic stability and offers a promising new avenue to design anticancer therapies. In this review, we summarize recent progress in three areas: (1) endogenous and exogenous factors that contribute to RS, (2) molecular mechanisms that mediate the cellular responses to RS, and (3) the large list of diseases that are directly or indirectly linked to RS.

  17. Coping Mechanisms Utah Agriculture Teachers Use to Manage Teaching Related Stress

    Science.gov (United States)

    Lawver, Rebecca G.; Smith, Kasee L.

    2014-01-01

    The purpose of this study was to examine the level of occupational stress among Utah agriculture teachers, and to determine the coping mechanisms utilized to manage teaching related stressful events. Teachers were asked to rank their level of occupational stress according to the scale used by the American Psychological Association Stress in…

  18. Nontypeable Haemophilus influenzae induces sustained lung oxidative stress and protease expression.

    Directory of Open Access Journals (Sweden)

    Paul T King

    Full Text Available Nontypeable Haemophilus influenzae (NTHi is a prevalent bacterium found in a variety of chronic respiratory diseases. The role of this bacterium in the pathogenesis of lung inflammation is not well defined. In this study we examined the effect of NTHi on two important lung inflammatory processes 1, oxidative stress and 2, protease expression. Bronchoalveolar macrophages were obtained from 121 human subjects, blood neutrophils from 15 subjects, and human-lung fibroblast and epithelial cell lines from 16 subjects. Cells were stimulated with NTHi to measure the effect on reactive oxygen species (ROS production and extracellular trap formation. We also measured the production of the oxidant, 3-nitrotyrosine (3-NT in the lungs of mice infected with this bacterium. NTHi induced widespread production of 3-NT in mouse lungs. This bacterium induced significantly increased ROS production in human fibroblasts, epithelial cells, macrophages and neutrophils; with the highest levels in the phagocytic cells. In human macrophages NTHi caused a sustained, extracellular production of ROS that increased over time. The production of ROS was associated with the formation of macrophage extracellular trap-like structures which co-expressed the protease metalloproteinase-12. The formation of the macrophage extracellular trap-like structures was markedly inhibited by the addition of DNase. In this study we have demonstrated that NTHi induces lung oxidative stress with macrophage extracellular trap formation and associated protease expression. DNase inhibited the formation of extracellular traps.

  19. From rainfed agriculture to stress-avoidance irrigation: II. Sustainability, crop yield, and profitability

    Science.gov (United States)

    Vico, Giulia; Porporato, Amilcare

    2011-02-01

    The optimality of irrigation strategies may be sought with respect to a number of criteria, including water requirements, crop yield, and profitability. To explore the suitability of different demand-based irrigation strategies, we link the probabilistic description of irrigation requirements under stochastic hydro-climatic conditions, provided in a companion paper [Vico G, Porporato A. From rainfed agriculture to stress-avoidance irrigation: I. A generalized irrigation scheme with stochastic soil moisture. Adv Water Resour 2011;34(2):263-71], to crop-yield and economic analyses. Water requirements, application efficiency, and investment costs of different irrigation methods, such as surface, sprinkler and drip irrigation systems, are described via a unified conceptual and theoretical approach, which includes rainfed agriculture and stress-avoidance irrigation as extreme cases. This allows us to analyze irrigation strategies with respect to sustainability, productivity, and economic return, using the same framework, and quantify them as a function of climate, crop, and soil parameters. We apply our results to corn ( Zea mays), a food staple and biofuel source, which is currently mainly irrigated through surface systems. As our analysis shows, micro-irrigation maximizes water productivity, but more traditional solutions may be more profitable at least in some contexts.

  20. Sustainable Development Mechanism of Food Culture’s Translocal Production Based on Authenticity

    Directory of Open Access Journals (Sweden)

    Guojun Zeng

    2014-10-01

    Full Text Available Food culture is a kind of non-material culture with authenticity. To achieve sustainable development of translocal heritage and food culture, we must protect its authenticity. By selecting the cases of the Dongbeiren Flavor Dumpling Restaurant and the Daozanjia Northeast Dumpling Restaurant and using the in-depth interview method, this study discusses how northeastern Cuisine in Guangzhou balances the inheritance and innovation of authenticity, how producers and customers negotiate, and how to realize sustainable development. The main conclusions are: first, there are two different paths of translocal food culture production, which are “authentic food culture production” and “differentiated food culture production”. Second, what translocal enterprises produce is not objective authenticity, but constructive authenticity, or even existential authenticity. Third, compared with differentiated food culture production, authentic food culture production is helpful for the sustainable development of local food culture production. It protects the locality while transmitting and developing the local culture. Fourth, translocal food culture production is a process in which the producers and consumers continue to interact to maintain a state of equilibrium, which informs the sustainable development mechanism with a high degree of authenticity.

  1. Stress echocardiography in patients who experienced mechanical ventilation weaning failure.

    Science.gov (United States)

    Ruiz-Bailén, Manuel; Cobo-Molinos, Jesús; Castillo-Rivera, Ana; Pola-Gallego-de-Guzmán, María Dolores; Cárdenas-Cruz, Antonio; Martínez-Amat, Antonio; Sevilla-Martínez, María; Hernández-Caballero, Clara

    2017-06-01

    Critically ill patients may suffer varying degrees of temporary myocardial dysfunction during respiratory weaning that could play an important role in weaning failure. In this study, we tried to assess the existence of temporary diastolic dysfunction during respiratory weaning. Inclusion period is from 2006 to 2015. In this study, we included 181 ventilated patients with cardiogenic shock that were being weaned from mechanical ventilation. Twenty of those patients were successfully weaned from mechanical ventilation, and the rest (161) experienced complications in their weaning process. All patients had a left ventricular ejection fraction >0.45 and E/E' ratio≤8, did not require vasoactive drugs at that time, and did not have remaining significant ischemic disease. We divided our patients into 3 groups, as follows: A, patients who could not tolerate a T-tube and required pressure-support ventilation (82); B, patients who successfully tolerated a T-tube period (20); and C, patients who could not tolerate spontaneous breathing modes of mechanical ventilation and remained on assisted mechanical ventilation. We performed stress echocardiography for the last two groups; using dobutamine to assess diastolic function and using ephedrine to evaluate functional mitral regurgitation (MR). We estimated pulmonary capillary wedge pressure through the E/E' ratio and the flow in the pulmonary veins. In group A (ie, those patients who could not tolerate a T-tube trial), we observed an increase in the E/E' ratio (6.32±0.77 vs 15.2±6.65; P=.0001) and a worsening of strain (S) and strain rate (SR) (-13.6±1.80 vs -11.88±5.6, P=.0001; and -1.3±1.28 vs -0.95±0.38, P=.0001; respectively). We did not observe a change in the E/E' ratio during stress echocardiogram on those patients with successful weaning from mechanical ventilation (7.41±0.43 vs 8.38±4.57, P=.001). However, we did see in this group an increased peak velocity of the S wave and of SR (-16.11±08.72 vs -19.89±5

  2. Integrin-dependent activation of the JNK signaling pathway by mechanical stress.

    Directory of Open Access Journals (Sweden)

    Andrea Maria Pereira

    Full Text Available Mechanical force is known to modulate the activity of the Jun N-terminal kinase (JNK signaling cascade. However, the effect of mechanical stresses on JNK signaling activation has previously only been analyzed by in vitro detection methods. It still remains unknown how living cells activate the JNK signaling cascade in response to mechanical stress and what its functions are in stretched cells.We assessed in real-time the activity of the JNK pathway in Drosophila cells by Fluorescence Lifetime Imaging Microscopy (FLIM, using an intramolecular phosphorylation-dependent dJun-FRET (Fluorescence Resonance Energy Transfer biosensor. We found that quantitative FRET-FLIM analysis and confocal microscopy revealed sustained dJun-FRET biosensor activation and stable morphology changes in response to mechanical stretch for Drosophila S2R+ cells. Further, these cells plated on different substrates showed distinct levels of JNK activity that associate with differences in cell morphology, integrin expression and focal adhesion organization.These data imply that alterations in the cytoskeleton and matrix attachments may act as regulators of JNK signaling, and that JNK activity might feed back to modulate the cytoskeleton and cell adhesion. We found that this dynamic system is highly plastic; at rest, integrins at focal adhesions and talin are key factors suppressing JNK activity, while multidirectional static stretch leads to integrin-dependent, and probably talin-independent, Jun sensor activation. Further, our data suggest that JNK activity has to coordinate with other signaling elements for the regulation of the cytoskeleton and cell shape remodeling associated with stretch.

  3. Improved Mechanical Properties and Sustained Release Behavior of Cationic Cellulose Nanocrystals Reinforeced Cationic Cellulose Injectable Hydrogels.

    Science.gov (United States)

    You, Jun; Cao, Jinfeng; Zhao, Yanteng; Zhang, Lina; Zhou, Jinping; Chen, Yun

    2016-09-12

    Polysaccharide-based injectable hydrogels have several advantages in the context of biomedical use. However, the main obstruction associated with the utilization of these hydrogels in clinical application is their poor mechanical properties. Herein, we describe in situ gelling of nanocomposite hydrogels based on quaternized cellulose (QC) and rigid rod-like cationic cellulose nanocrystals (CCNCs), which can overcome this challenge. In all cases, gelation immediately occurred with an increase of temperature, and the CCNCs were evenly distributed throughout the hydrogels. The nanocomposite hydrogels exhibited increasing orders-of-magnitude in the mechanical strength, high extension in degradation and the sustained release time, because of the strong interaction between CCNCs and QC chains mediated by the cross-linking agent (β-glycerophosphate, β-GP). The results of the in vitro toxicity and in vivo biocompatibility tests revealed that the hydrogels did not show obvious cytotoxicity and inflammatory reaction to cells and tissue. Moreover, DOX-encapsulated hydrogels were injected beside the tumors of mice bearing liver cancer xenografts to assess the potential utility as localized and sustained drug delivery depot systems for anticancer therapy. The results suggested that the QC/CCNC/β-GP nanocomposite hydrogels had great potential for application in subcutaneous and sustained delivery of anticancer drug to increase therapeutic efficacy and improve patient compliance.

  4. Improving environmental sustainability of concrete products: Investigation on MWC thermal and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Becchio, Cristina; Corgnati, Stefano Paolo; Kindinis, Andrea [Department of Energetics (DENER), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Pagliolico, Simonetta [Department of Materials Science and Engineering Chemistry (DISMIC), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy)

    2009-11-15

    This research focuses on the possibility of constituting a more sustainable lightweight concrete, Mineralized Wood Concrete (MWC), substituting natural aggregates with wastes from woodworking activities. Exploiting this type of aggregates, a triple purpose has been achieved: preservation of natural raw materials, reuse of wastes and energy saving. Furthermore, the use of wood aggregates is a way to try to develop a sustainable concrete characterized by high thermal inertia, high thermal resistance and low weight. In this paper, effects of the addition of wood aggregates on mechanical and thermal properties of concrete are studied. Mechanical performances have been investigated with compressive strength tests, while a one-dimensional heat flow model has been used to predict the thermal conductivity of MWC. The use of MWC can be associated with the idea of a different typology of relatively heavy building envelope: this union could competitively answer to the demand of well-insulated building envelope and concurrently characterized by high thermal mass. From this union, a series of other values can be derived: low weight, environmentally friendly, easily industrialized and easy on-site casting. Consequently, applications of wood concrete in building constructions may be an interesting solution in order to improve sustainability and building energy efficiency. (author)

  5. Mechanisms involved in regulation of osteoclastic differentiation by mechanical stress-loaded osteoblasts

    Energy Technology Data Exchange (ETDEWEB)

    Kaneuji, Takeshi [Division of Oral and Maxillofacial Reconstructive Surgery, Department of Oral and Maxillofacial Surgery, Kyushu Dental College, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu 803-8580 (Japan); Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental College, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu 803-8580 (Japan); Ariyoshi, Wataru; Okinaga, Toshinori; Toshinaga, Akihiro [Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental College, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu 803-8580 (Japan); Takahashi, Tetsu [Division of Oral and Maxillofacial Reconstructive Surgery, Department of Oral and Maxillofacial Surgery, Kyushu Dental College, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu 803-8580 (Japan); Oral Bioresearch Center, Kyushu Dental College, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu 803-8580 (Japan); Nishihara, Tatsuji, E-mail: tatsujin@kyu-dent.ac.jp [Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental College, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu 803-8580 (Japan); Oral Bioresearch Center, Kyushu Dental College, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu 803-8580 (Japan)

    2011-04-29

    Highlights: {yields} Effect of compressive force on osteoblasts were examined. {yields} Compressive force induced OPG expression and suppressed osteoclastogenesis. {yields} This enhancement of OPG is dependent on Wnt/Ca2+ signal pathway. -- Abstract: Mechanical stress is known to be important for regulation of bone turnover, though the detailed mechanisms are not fully understood. In the present study, we examined the effect of mechanical stress on osteoblasts using a novel compression model. Mouse osteoblastic MC3T3-E1 cells were embedded in three-dimensional (3D) gels and cultured with continuous compressive force (0-10.0 g/cm{sup 2}) for 48 h, and the conditioned medium were collected. RAW264.7 cells were then incubated with the conditioned medium for various times in the presence of receptor activator of nuclear factor-{kappa}B ligand (RANKL). Conditioned medium was found to inhibit the differentiation of RAW264.7 cells into osteoclasts induced by RANKL via down-regulation of the expression of tumor necrosis factor receptor-associated factor 6 (TRAF6), phosphorylation of I{kappa}B{alpha}, and nuclear translocation of p50 and p65. Interestingly, the conditioned medium also had a high level of binding activity to RANKL and blocked the binding of RANK to RANKL. Furthermore, the binding activity of conditioned medium to RANKL was reduced when the 3D gel was supplemented with KN-93, an inhibitor of non-canonical Wnt/Ca{sup 2+} pathway. In addition, expression level of osteoprotegerin (OPG) mRNA was increased in time- and force-dependent manners, and remarkably suppressed by KN-93. These results indicate that osteoblastic cells subjected to mechanical stress produce OPG, which binds to RANKL. Furthermore, this binding activity strongly inhibited osteoclastogenesis through suppression of TRAF6 and the nuclear factor-kappa B (NF-{kappa}B) signaling pathway, suggesting that enhancement of OPG expression induced by mechanical stress is dependent on non-canonical Wnt

  6. Large-amplitude internal waves sustain coral health during thermal stress

    Science.gov (United States)

    Schmidt, Gertraud M.; Wall, Marlene; Taylor, Marc; Jantzen, Carin; Richter, Claudio

    2016-09-01

    Ocean warming is a major threat for coral reefs causing widespread coral bleaching and mortality. Potential refugia are thus crucial for coral survival. Exposure to large-amplitude internal waves (LAIW) mitigated heat stress and ensured coral survival and recovery during and after an extreme heat anomaly. The physiological status of two common corals, Porites lutea and Pocillopora meandrina, was monitored in host and symbiont traits, in response to LAIW-exposure throughout the unprecedented 2010 heat anomaly in the Andaman Sea. LAIW-exposed corals of both species survived and recovered, while LAIW-sheltered corals suffered partial and total mortality in P. lutea and P. meandrina, respectively. LAIW are ubiquitous in the tropics and potentially generate coral refuge areas. As thermal stress to corals is expected to increase in a warming ocean, the mechanisms linking coral bleaching to ocean dynamics will be crucial to predict coral survival on a warming planet.

  7. Thermal stability of nafion membranes under mechanical stress

    Energy Technology Data Exchange (ETDEWEB)

    Quintilii, M.; Struis, R. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    The feasibility of adequately modified fluoro-ionomer membranes (NAFION{sup R}) is demonstrated for the selective separation of methanol synthesis products from the raw reactor gas at temperatures around 200{sup o}C. For an economically relevant application of this concept on a technical scale the Nafion membranes should be thin ({approx_equal}10 {mu}m) and thermally stable over a long period of time (1-2 years). In cooperation with industry (Methanol Casale SA, Lugano (CH)), we test the thermal stability of Nafion hollow fibers and supported Nafion thin sheet membranes at temperatures between 160 and 200{sup o}C under mechanical stress by applying a gas pressure difference over the membrane surface ({Delta}P{<=} 40 bar). Tests with the hollow fibers revealed that Nafion has visco-elastic properties. Tests with 50 {mu}m thin Nafion sheets supported by a porous metal carrier at 200{sup o}C and {Delta}P=39 bar showed no mechanical defects over a period of 92 days. (author) 5 figs., 4 refs.

  8. Exploring mechanisms for mobilising industrial sustainability models across different industrial locations

    DEFF Research Database (Denmark)

    Jacobsen, Ole Morten Noel Brings

    2009-01-01

    Industrial symbiosis is a model of sustainability which suggests that agglomerations of industries can achieve considerable environmental benefits by engaging in inter-organisational waste recycling, energy cascading and water recovery. This article considers how such a complex inter......-organisational model for environmental management can be mobilised across different industrial localities. It is suggested that companies engaged in industrial symbiosis activities at one production locality may be more inclined to engage in symbiotic activities when entering a new production locality. The industrial...... symbiosis model may in this way be mobilised across industrial localities as part of the global corporate search for marked access and cost reductions. This suggestion is supported by an illustrative case study shedding some light on the mechanisms for mobilising sustainability models across localities....

  9. A mechanism for sustained groundwater pressure changes induced by distant earthquakes

    Science.gov (United States)

    Brodsky, E.E.; Roeloffs, E.; Woodcock, D.; Gall, I.; Manga, M.

    2003-01-01

    Large sustained well water level changes (>10 cm) in response to distant (more than hundreds of kilometers) earthquakes have proven enigmatic for over 30 years. Here we use high sampling rates at a well near Grants Pass, Oregon, to perform the first simultaneous analysis of both the dynamic response of water level and sustained changes, or steps. We observe a factor of 40 increase in the ratio of water level amplitude to seismic wave ground velocity during a sudden coseismic step. On the basis of this observation we propose a new model for coseismic pore pressure steps in which a temporary barrier deposited by groundwater flow is entrained and removed by the more rapid flow induced by the seismic waves. In hydrothermal areas, this mechanism could lead to 4 ?? 10-2 MPa pressure changes and triggered seismicity.

  10. Cell wall pectic arabinans influence the mechanical properties of Arabidopsis thaliana inflorescence stems and their response to mechanical stress.

    Science.gov (United States)

    Verhertbruggen, Yves; Marcus, Susan E; Chen, Jianshe; Knox, J Paul

    2013-08-01

    Little is known of the dynamics of plant cell wall matrix polysaccharides in response to the impact of mechanical stress on plant organs. The capacity of the imposition of a mechanical stress (periodic brushing) to reduce the height of the inflorescence stem of Arabidopsis thaliana seedlings has been used to study the role of pectic arabinans in the mechanical properties and stress responsiveness of a plant organ. The arabinan-deficient-1 (arad1) mutation that affects arabinan structures in epidermal cell walls of inflorescence stems is demonstrated to reduce the impact on inflorescence stem heights caused by mechanical stress. The arabinan-deficient-2 (arad2) mutation, that does not have detectable impact on arabinan structures, is also shown to reduce the impact on stem heights caused by mechanical stress. The LM13 linear arabinan epitope is specifically detected in epidermal cell walls of the younger, flexible regions of inflorescence stems and increases in abundance at the base of inflorescence stems in response to an imposed mechanical stress. The strain (percentage deformation) of stem epidermal cells in the double mutant arad1 × arad2 is lower in unbrushed plants than in wild-type plants, but rises to wild-type levels in response to brushing. The study demonstrates the complexity of arabinan structures within plant cell walls and also that their contribution to cell wall mechanical properties is a factor influencing responsiveness to mechanical stress.

  11. Shared and unique responses of plants to multiple individual stresses and stress combinations: physiological and molecular mechanisms

    Directory of Open Access Journals (Sweden)

    Prachi ePandey

    2015-09-01

    Full Text Available In field conditions, plants are often simultaneously exposed to multiple biotic and abiotic stresses resulting in substantial yield loss. Plants have evolved various physiological and molecular adaptations to protect themselves under stress combinations. Emerging evidences suggest that plant responses to a combination of stresses are unique from individual stress responses. In addition, plants exhibit shared responses which are common to individual stresses and stress combination. In this review, we provide an update on the current understanding of both unique and shared responses. Specific focus of this review is on heat-drought stress as a major abiotic stress combination and, drought-pathogen and heat-pathogen as examples of abiotic-biotic stress combinations. We also comprehend the current understanding of molecular mechanisms of cross talk in relation to shared and unique molecular responses for plant survival under stress combinations. Thus, the knowledge of shared responses of plants from individual stress studies and stress combinations can be utilized to develop varieties with broad spectrum stress tolerance.

  12. Shared and unique responses of plants to multiple individual stresses and stress combinations: physiological and molecular mechanisms.

    Science.gov (United States)

    Pandey, Prachi; Ramegowda, Venkategowda; Senthil-Kumar, Muthappa

    2015-01-01

    In field conditions, plants are often simultaneously exposed to multiple biotic and abiotic stresses resulting in substantial yield loss. Plants have evolved various physiological and molecular adaptations to protect themselves under stress combinations. Emerging evidences suggest that plant responses to a combination of stresses are unique from individual stress responses. In addition, plants exhibit shared responses which are common to individual stresses and stress combination. In this review, we provide an update on the current understanding of both unique and shared responses. Specific focus of this review is on heat-drought stress as a major abiotic stress combination and, drought-pathogen and heat-pathogen as examples of abiotic-biotic stress combinations. We also comprehend the current understanding of molecular mechanisms of cross talk in relation to shared and unique molecular responses for plant survival under stress combinations. Thus, the knowledge of shared responses of plants from individual stress studies and stress combinations can be utilized to develop varieties with broad spectrum stress tolerance.

  13. On the relative significance of lithospheric weakening mechanisms for sustained plate tectonics

    Science.gov (United States)

    Araceli Sanchez-Maes, Sophia

    2018-01-01

    Plate tectonics requires the bending of strong plates at subduction zones, which is difficult to achieve without a secondary weakening mechanism. Two classes of weakening mechanisms have been proposed for the generation of ongoing plate tectonics, distinguished by whether or not they require water. Here we show that the energy budget of global subduction zones offers a simple yet decisive test on their relative significance. Theoretical studies of mantle convection suggest bending dissipation to occupy only 10-20 % of total dissipation in the mantle, and our results indicate that the hydrous mechanism in the shallow part of plates is essential to satisfy the requirement. Thus, surface oceans are required for the long-term operation of plate tectonics on terrestrial worlds. Establishing this necessary and observable condition for sustained plate tectonics carries important implications for planetary habitability at large.

  14. Sustainability of Recycled ABS and PA6 by Banana Fiber Reinforcement: Thermal, Mechanical and Morphological Properties

    Science.gov (United States)

    Singh, Rupinder; Kumar, Ranvijay; Ranjan, Nishant

    2018-01-01

    In the present study efforts have been made to prepare functional prototypes with improved thermal, mechanical and morphological properties from polymeric waste for sustainability. The primary recycled acrylonitrile butadiene styrene (ABS) and polyamide 6 (PA6) has been selected as matrix material with bio-degradable and bio-compatible banana fibers (BF) as reinforcement. The blend (in form of feed stock filament wire) of ABS/PA6 and BF was prepared in house by conventional twin screw extrusion (TSE) process. Finally feed stock filament of ABS/PA6 reinforced with BF was put to run on open source fused deposition modelling based three dimensional printer (without any change in hardware/software of the system) for printing of functional prototypes with improved thermal/mechanical/morphological properties. The results are supported by photomicrographs, thermographs and mechanical testing.

  15. Mechanization of Conservation Agriculture for Smallholders: Issues and Options for Sustainable Intensification

    Directory of Open Access Journals (Sweden)

    Brian Sims

    2015-05-01

    Full Text Available Conservation agriculture (CA is an increasingly adopted production system to meet the goals of sustainable crop production intensification in feeding a growing world population whilst conserving natural resources. Mechanization (especially power units, seeders, rippers and sprayers is a key input for CA and smallholder farmers often have difficulties in making the necessary investments. Donors may be able to provide mechanization inputs in the short term, but this is not a sustainable solution as a machinery input supply chain needs to be built up to continue availability after external interventions cease. Local manufacture should be supported, as was the case in Brazil, but this is a slow development process, especially in sub-Saharan Africa. A more immediate solution is to equip and train CA service provision entrepreneurs. With the right equipment, selected for the needs of their local clientele, and the right technical and business management training, such entrepreneurs can make a livelihood by supplying high quality CA and other mechanization services on a fully costed basis. Elements of the required training, based on extensive field experience, are provided. To catalyse the growth of CA providers’ business, the market can be stimulated for an initial period by issuing e-vouchers for services and inputs.

  16. Mechanical Pre-Stressing a Transducer through a Negative DC Biasing Field

    Science.gov (United States)

    2017-04-21

    NUWC-NPT Technical Report 12,224 21 April 2017 Mechanical Pre-Stressing a Transducer through a Negative DC Biasing Field Stephen C...TITLE AND SUBTITLE Mechanical Pre-Stressing a Transducer through a Negative DC Biasing Field 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c...with regards to the feasibility of using a negative DC biasing approach to apply a mechanical compressive stress to a transducer’s piezoelectric

  17. Stress and Coping Mechanism Towards Menstrual Cycle Disorder to Teenager Girl

    OpenAIRE

    Astuti, Vitaria Wahyu; Mesarini, Bisma Ayu

    2013-01-01

    Everyone has experienced stress and become motivated to do coping mechanism. The purpose of this study to analyze the relationship between stress and coping mechanisms of the menstrual cycle disorders. The design used was cross sectional. The populations were grade IV student at STIKES RS Baptis Kediri. The samples were 35 respondents using purposive sampling. The independent variable was coping mechanism. The dependent variable was level of stress towards period disorders. Data were collec...

  18. Stress and PTSD Mechanisms as Targets for Pharmacotherapy of Alcohol Abuse, Addiction and Relapse

    Science.gov (United States)

    2017-10-01

    AWARD NUMBER: W81XWH-13-1-0126 TITLE: Stress and PTSD Mechanisms as Targets for Pharmacotherapy of Alcohol Abuse, Addiction and Relapse PRINCIPAL...10/27/2017 2. REPORT TYPE Annual 3. DATES COVERED 30 Sep 2016 — 29 Sep 2017 4. TITLE AND SUBTITLE Stress and PTSD Mechanisms as Targets for...insights into mechanism; (2) suppression of noradrenergic signaling decreases alcohol drinking in rats with a history of traumatic stress , but not in

  19. Stress Management in Education: Warning Signs and Coping Mechanisms

    Science.gov (United States)

    Sorenson, Richard D.

    2007-01-01

    Only in recent years have researchers begun to study stress in the workplace. Psychologists and other stress analysts have discovered that the most trying professions are those that involve high pressure and serious responsibilities, often beyond the control of the individuals employed. Most interesting, the American Institute of Stress revealed…

  20. Aetiology and mechanisms of injury in medial tibial stress syndrome: Current and future developments.

    Science.gov (United States)

    Franklyn, Melanie; Oakes, Barry

    2015-09-18

    Medial tibial stress syndrome (MTSS) is a debilitating overuse injury of the tibia sustained by individuals who perform recurrent impact exercise such as athletes and military recruits. Characterised by diffuse tibial anteromedial or posteromedial surface subcutaneous periostitis, in most cases it is also an injury involving underlying cortical bone microtrauma, although it is not clear if the soft tissue or cortical bone reaction occurs first. Nuclear bone scans and magnetic resonance imaging (MRI) can both be used for the diagnosis of MTSS, but the patient's history and clinical symptoms need to be considered in conjunction with the imaging findings for a correct interpretation of the results, as both imaging modalities have demonstrated positive findings in the absence of injury. However, MRI is rapidly becoming the preferred imaging modality for the diagnosis of bone stress injuries. It can also be used for the early diagnosis of MTSS, as the developing periosteal oedema can be identified. Retrospective studies have demonstrated that MTSS patients have lower bone mineral density (BMD) at the injury site than exercising controls, and preliminary data indicates the BMD is lower in MTSS subjects than tibial stress fracture (TSF) subjects. The values of a number of tibial geometric parameters such as cross-sectional area and section modulus are also lower in MTSS subjects than exercising controls, but not as low as the values in TSF subjects. Thus, the balance between BMD and cortical bone geometry may predict an individual's likelihood of developing MTSS. However, prospective longitudinal studies are needed to determine how these factors alter during the development of the injury and to find the detailed structural cause, which is still unknown. Finite element analysis has recently been used to examine the mechanisms involved in tibial stress injuries and offer a promising future tool to understand the mechanisms involved in MTSS. Contemporary accurate diagnosis

  1. COMPANY SUSTAINABILITY PROVISION ORGANIZATIONAL MECHANISM AS ALTERNATIVE TO ANTI-CRISIS MANAGEMENT

    Directory of Open Access Journals (Sweden)

    A. D. Bobryshev

    2012-01-01

    Full Text Available Experience available for practical implementation of anti-crisis company (particularly industrial enterprise management methods under conditions of proceeding destruction of scientifi c and technical potential of the country proves their ineff ectiveness, so other theoretical and practical solutions capable of changing the situation are to be searched. In this respect, creation of an organizational mechanism for a company to function sustainably through minimization of the infl uence of crisis phenomena consequences on activities of the company seems to have good prospects.

  2. Mix design and mechanical performance of geopolymer binder for sustainable construction and building material

    Science.gov (United States)

    Saeli, Manfredi; Novais, Rui M.; Seabra, Maria Paula; Labrincha, João A.

    2017-11-01

    Sustainability in construction is a major concern worldwide, due to the huge volume of materials and energy consumed by this sector. Associated supplementing industries (e.g. Portland cement production) constitute a significant source of CO2 emissions and global warming. Valorisation and reuse of industrial wastes and by-products make geopolymers a solid and sustainable via to be followed as a valid alternative to Portland cement. In this work the mix design of a green fly ash-based geopolymer is evaluated as an environmentally friendly construction material. In the pursuit of sustainability, wastes from a regional kraft pulp industry are exploited for the material processing. Furthermore, a simple, reproducible, and low-cost manufacture is used. The mix design is hence optimised in order to improve the desirable mechanical performance of the material intended for structural applications in construction. Tests indicate that geopolymers may efficiently substitute the ordinary Portland cement as a mortar/concrete binder. Furthermore, valorisation and reuse of wastes in geopolymers is a suboptimal way of gaining financial surplus for the involved industrial players, while contributes for the implementation of a desirable circular economy.

  3. Mathematical modeling of sustainable synaptogenesis by repetitive stimuli suggests signaling mechanisms in vivo.

    Directory of Open Access Journals (Sweden)

    Hiromu Takizawa

    Full Text Available The mechanisms of long-term synaptic maintenance are a key component to understanding the mechanism of long-term memory. From biological experiments, a hypothesis arose that repetitive stimuli with appropriate intervals are essential to maintain new synapses for periods of longer than a few days. We successfully reproduce the time-course of relative numbers of synapses with our mathematical model in the same conditions as biological experiments, which used Adenosine-3', 5'-cyclic monophosphorothioate, Sp-isomer (Sp-cAMPS as external stimuli. We also reproduce synaptic maintenance responsiveness to intervals of Sp-cAMPS treatment accompanied by PKA activation. The model suggests a possible mechanism of sustainable synaptogenesis which consists of two steps. First, the signal transduction from an external stimulus triggers the synthesis of a new signaling protein. Second, the new signaling protein is required for the next signal transduction with the same stimuli. As a result, the network component is modified from the first network, and a different signal is transferred which triggers the synthesis of another new signaling molecule. We refer to this hypothetical mechanism as network succession. We build our model on the basis of two hypotheses: (1 a multi-step network succession induces downregulation of SSH and COFILIN gene expression, which triggers the production of stable F-actin; (2 the formation of a complex of stable F-actin with Drebrin at PSD is the critical mechanism to achieve long-term synaptic maintenance. Our simulation shows that a three-step network succession is sufficient to reproduce sustainable synapses for a period longer than 14 days. When we change the network structure to a single step network, the model fails to follow the exact condition of repetitive signals to reproduce a sufficient number of synapses. Another advantage of the three-step network succession is that this system indicates a greater tolerance of parameter

  4. Oxidative Stress in Neurodegenerative Diseases: Mechanisms and Therapeutic Perspectives

    Directory of Open Access Journals (Sweden)

    Ailton Melo

    2011-01-01

    Full Text Available The incidence and prevalence of neurodegenerative diseases (ND increase with life expectancy. This paper reviews the role of oxidative stress (OS in ND and pharmacological attempts to fight against reactive oxygen species (ROS-induced neurodegeneration. Several mechanisms involved in ROS generation in neurodegeneration have been proposed. Recent articles about molecular pathways involved in ROS generation were reviewed. The progress in the development of neuroprotective therapies has been hampered because it is difficult to define targets for treatment and determine what should be considered as neuroprotective. Therefore, the attention was focused on researches about pharmacological targets that could protect neurons against OS. Since it is necessary to look for genes as the ultimate controllers of all biological processes, this paper also tried to identify gerontogenes involved in OS and neurodegeneration. Since neurons depend on glial cells to survive, recent articles about the functioning of these cells in aging and ND were also reviewed. Finally, clinical trials testing potential neuroprotective agents were critically reviewed. Although several potential drugs have been screened in in vitro and in vivo models of ND, these results were not translated in benefit of patients, and disappointing results were obtained in the majority of clinical trials.

  5. Exercise as a Stress Coping Mechanism in a Pharmacy Student Population.

    Science.gov (United States)

    Garber, Mathew C

    2017-04-01

    Objective. To assess the coping mechanisms used by pharmacy students and their relationship to perceived stress. Methods. Data were gathered utilizing the Perceived Stress Scale (PSS10) and Brief COPE with the additional coping mechanisms of exercise and use of prescribed medications. Results. A survey that was sent to 368 students had an 81% response rate. Perceived stress was significantly higher than standard populations, but consistent with other pharmacy student populations. The most frequently reported coping mechanisms were the adaptive strategies of active coping, acceptance and planning. Maladaptive strategies of behavioral disengagement, venting and self-blame were significantly associated with higher perceived stress scores and the new addition of an exercise coping mechanism significantly associated with lower perceived stress scores. Use of prescribed medications was not significantly associated with perceived stress levels. Conclusion. Inclusion of exercise as a coping mechanism may be beneficial in similar populations.

  6. Soil memory as a potential mechanism for encouraging sustainable plant health and productivity.

    Science.gov (United States)

    Lapsansky, Erin R; Milroy, Arwen M; Andales, Marie J; Vivanco, Jorge M

    2016-04-01

    The unspecified components of plant-microbe and plant-microbiome associations in the rhizosphere are complex, but recent research is simplifying our understanding of these relationships. We propose that the strong association between hosts, symbionts, and pathogens could be simplified by the concept of soil memory, which explains how a plant could promote their fecundity and protect their offspring through tightly associated relationships with the soil. Although there are many questions surrounding the mechanisms of this phenomenon, recent research has exposed evidence of its existence. Along with evidence from observations and mechanisms related to soil memory, we report means to utilize our understanding as sustainable protection for agricultural crops and propose future research questions. Copyright © 2016. Published by Elsevier Ltd.

  7. Sustainable Agricultural Mechanization for Smallholders: What Is It and How Can We Implement It?

    Directory of Open Access Journals (Sweden)

    Brian Sims

    2017-06-01

    Full Text Available Smallholder farmers are the main producers of the world’s food and they will have to increase production by up to 100 percent by 2050 to feed the growing population. This must be achieved while preserving natural resources and that is why sustainable agricultural mechanization (SAM will be fundamental to the process. SAM is climate-smart and environmentally benign and essentially means no-till conservation agriculture, which requires specific mechanization inputs. Principally, these are seeders and planters capable of penetrating soil surface vegetative cover to deposit seed and fertilizer at the required depth and spacing; and equipment for management of cover crops and weeds. Mechanization is required not only for crop production, but also for processing and along the entire value chain. Mechanization inputs are usually expensive and so specialist service provision will be the indicated way forward. This will need collaboration from both the private and public sectors and will involve public-private partnerships to be developed in one form or another. Given the poor track record of public sector mechanization provision, the delivery of SAM should be firmly in the hands of the private sector that should be committed to SAM principles or otherwise be incentivized to the concept through smart subsidies. Improved information flows via smallholder farmer-friendly innovation platforms; and continuing development and testing of SAM technologies via regional centres of excellence will both be required—especially for sub-Saharan Africa.

  8. Dysregulated stress signal sensitivity and inflammatory disinhibition as a pathophysiological mechanism of stress-related chronic fatigue.

    Science.gov (United States)

    Strahler, Jana; Skoluda, Nadine; Rohleder, Nicolas; Nater, Urs M

    2016-09-01

    Chronic stress and its subsequent effects on biological stress systems have long been recognized as predisposing and perpetuating factors in chronic fatigue, although the exact mechanisms are far from being completely understood. In this review, we propose that sensitivity of immune cells to glucocorticoids (GCs) and catecholamines (CATs) may be the missing link in elucidating how stress turns into chronic fatigue. We searched for in vitro studies investigating the impact of GCs or CATs on mitogen-stimulated immune cells in chronically stressed or fatigued populations, with 34 original studies fulfilling our inclusion criteria. Besides mixed cross-sectional findings for stress- and fatigue-related changes of GC sensitivity under basal conditions or acute stress, longitudinal studies indicate a decrease with ongoing stress. Research on CATs is still scarce, but initial findings point towards a reduction of CAT sensitivity under chronic stress. In the long run, resistance of immune cells to stress signals under conditions of chronic stress might translate into self-maintaining inflammation and inflammatory disinhibition under acute stress, which in turn lead to fatigue. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Spartan Release Engagement Mechanism (REM) stress and fracture analysis

    Science.gov (United States)

    Marlowe, D. S.; West, E. J.

    1984-01-01

    The revised stress and fracture analysis of the Spartan REM hardware for current load conditions and mass properties is presented. The stress analysis was performed using a NASTRAN math model of the Spartan REM adapter, base, and payload. Appendix A contains the material properties, loads, and stress analysis of the hardware. The computer output and model description are in Appendix B. Factors of safety used in the stress analysis were 1.4 on tested items and 2.0 on all other items. Fracture analysis of the items considered fracture critical was accomplished using the MSFC Crack Growth Analysis code. Loads and stresses were obtaind from the stress analysis. The fracture analysis notes are located in Appendix A and the computer output in Appendix B. All items analyzed met design and fracture criteria.

  10. A comprehensive investigation into the effect of temperature variation on the mechanical properties of sustainable concrete

    Directory of Open Access Journals (Sweden)

    El Mir Abdulkader

    2017-01-01

    Full Text Available Minimizing the production energy and resources consumption are the key principle for engineering sustainability. In the case of concrete structures, this concept can be achieved by the use of materials in the most efficient way considering in the mix design the optimal mechanical and durability properties. The substitution of ordinary Portland cement for other supplementary cementitious materials is assessing the possibility of enhancing the sustainability and decreasing the environmental impact of concrete. Mass concrete is rich in cementitious materials which results in high temperature within the concrete, hence several hazards such as cracking or temperature differences between the interior and the surface of concrete could be prevented. An experimental study evaluated on several one cubic meter sized concrete elements in which during the primary phase of hydration, the temperature variation is recorded in several location offsets with respect to time. Thermal variations results are analyzed in accordance with the cement type, CO2 emission production of cement, compressive strength, water tightness, drying shrinkage and rapid chloride migration coefficient. The results indicate that slag cement CEM III/B 32.5, that incorporates highest amount of slag, ensured improved mechanical, thermal and durability properties in comparison with ordinary Portland cement CEM I 32.5.

  11. Polymer excipients enable sustained drug release in low pH from mechanically strong inorganic geopolymers.

    Science.gov (United States)

    Jämstorp, Erik; Yarra, Tejaswi; Cai, Bing; Engqvist, Håkan; Bredenberg, Susanne; Strømme, Maria

    2012-01-01

    Improving acid resistance, while maintaining the excellent mechanical stability is crucial in the development of a sustained and safe oral geopolymer dosage form for highly potent opioids. In the present work, commercially available Methacrylic acid-ethyl acrylate copolymer, Polyethylene-glycol (PEG) and Alginate polymer excipients were included in dissolved or powder form in geopolymer pellets to improve the release properties of Zolpidem, herein acting as a model drug for the highly potent opioid Fentanyl. Scanning electron microscopy, compression strength tests and drug release experiments, in gastric pH 1 and intestinal pH 6.8 conditions, were performed. The polymer excipients, with an exception for PEG, reduced the drug release rate in pH 1 due to their ability to keep the pellets in shape, in combination with the introduction of an insoluble excipient, and thereby maintain a barrier towards drug diffusion and release. Neither geopolymer compression strength nor the release in pH 6.8 was considerably impaired by the incorporation of the polymer excipients. The geopolymer/polymer composites combine high mechanical strength and good release properties under both gastric and intestinal pH conditions, and are therefore promising oral dosage forms for sustained release of highly potent opioids.

  12. Mechanical-tactile stimulation (MTS) during neonatal stress prevents hyperinsulinemia despite stress-induced adiposity in weanling rat pups.

    Science.gov (United States)

    Moyer-Mileur, Laurie J; Haley, Shannon; Gulliver, Kristina; Thomson, Anne; Slater, Hillarie; Barrett, Brett; Joss-Moore, Lisa A; Callaway, Christopher; McKnight, Robert A; Moore, Barry; Lane, Robert H

    2011-03-01

    Stress in early life negatively influences growth quality through perturbations in body composition including increased fat mass. At term (40 weeks) preterm infants have greater fat mass and abdominal visceral adipose tissue than term-born infants. Mechanical-tactile stimulation (MTS) attenuates the stress response in preterm infants and rodents. We tested the hypothesis that MTS, administered during an established model of neonatal stress, would decrease stress-driven adiposity and prevent associated metabolic imbalances in rat pups. Pups received one of three treatments from postnatal days 5 to P9: Neonatal Stress (Stress; n=20) = painful stimulus and hypoxic/hyperoxic challenge during 60 min of maternal separation; MTS (n=20) = neonatal stress+10 min of MTS; or Control (n=20). Body weight, DXA whole body fat mass (g), MRI subcutaneous and visceral adipose tissue, and fasting adiponectin, leptin, glucose, insulin, and corticosterone were measured at weaning (P21). Stress and MTS weight gain (g/d) were accelerated following neonatal stress with greater fat mass, abdominal subcutaneous adipose tissue, serum adiponectin, leptin, and fasting glucose at weaning (P21). Male Stress and MTS pups had greater visceral adipose tissue depot. Male and female Stress pups were hyperinsulinemic. In summary, neonatal stress compromised body composition by increasing fat mass and abdominal subcutaneous adipose tissue depot, and in males, visceral adipose tissue depot. Importantly, MTS prevented hyperinsulinemia despite of stress-induced adiposity. We conclude that MTS during neonatal stress has the potential to minimize metabolic consequences associated with stress-driven perturbations in fat mass and abdominal adipose depots. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  13. Influence of effective stress coefficient on mechanical failure of chalk

    DEFF Research Database (Denmark)

    Alam, Mohammad Monzurul; Fabricius, Ida Lykke; Hjuler, M.L.

    2012-01-01

    The Effective stress coefficient is a measure of how chalk grains are connected with each other. The stiffness of chalk may decrease if the amount of contact cements between the grains decreases, which may lead to an increase of the effective stress coefficient. We performed CO2 injection in chal...... precise failure strength of chalk during changed stress state and under the influence of chemically reactive fluids during production of hydrocarbon and geological storage CO2....

  14. Measuring Propellant Stress Relaxation Modulus Using Dynamic Mechanical Analyzer

    Science.gov (United States)

    2017-03-29

    Article 3. DATES COVERED (From - To) 04 August 2016 – 29 March 2017 4. TITLE AND SUBTITLE Measuring Propellant Stress Relaxation Modulus Using Dynamic...ERC 14. ABSTRACT A method for determining the stress relaxation master curve of solid rocket propellants was developed. The propellant was tested in... stress relaxation modulus, Mpa; E∞ = long-term equilibrium modulus, Mpa; E0 = storage modulus, Mpa; E0 0 = loss modulus, Mpa; F = Fisher test

  15. Stress and the social brain: behavioural effects and neurobiological mechanisms

    OpenAIRE

    Sandi Carmen; Haller József

    2015-01-01

    Stress often affects our social lives. When undergoing high level or persistent stress individuals frequently retract from social interactions and become irritable and hostile. Predisposition to antisocial behaviours — including social detachment and violence — is also modulated by early life adversity; however the effects of early life stress depend on the timing of exposure and genetic factors. Research in animals and humans has revealed some of the structural functional and molecular chang...

  16. Adult Literacy Education Program Administrators' Perceptions of Occupational Stress and Coping Mechanisms

    Science.gov (United States)

    Engelmann, Stephanie

    2014-01-01

    Job performance may be adversely affected by stress. Job stress is a primary contributor to serious physical and emotional health consequences. This quantitative study examined adult literacy program administrator perceptions of occupational stress and coping mechanisms related to job satisfaction, job efficacy, career longevity, and overall…

  17. Stress and the social brain: behavioural effects and neurobiological mechanisms.

    Science.gov (United States)

    Sandi, Carmen; Haller, József

    2015-05-01

    Stress often affects our social lives. When undergoing high-level or persistent stress, individuals frequently retract from social interactions and become irritable and hostile. Predisposition to antisocial behaviours - including social detachment and violence - is also modulated by early life adversity; however, the effects of early life stress depend on the timing of exposure and genetic factors. Research in animals and humans has revealed some of the structural, functional and molecular changes in the brain that underlie the effects of stress on social behaviour. Findings in this emerging field will have implications both for the clinic and for society.

  18. Mechanisms of Nanoparticle-Induced Oxidative Stress and Toxicity

    National Research Council Canada - National Science Library

    Manke, Amruta; Wang, Liying; Rojanasakul, Yon

    2013-01-01

    .... Oxidative stress induced by engineered NP is due to acellular factors such as particle surface, size, composition, and presence of metals, while cellular responses such as mitochondrial respiration...

  19. Mechanical stress activates neurites and somata of myenteric neurons

    Directory of Open Access Journals (Sweden)

    Eva Maria Kugler

    2015-09-01

    Full Text Available The particular location of myenteric neurons, sandwiched between the 2 muscle layers of the gut, implies that their somata and neurites undergo mechanical stress during gastrointestinal motility. Existence of mechanosensitive enteric neurons (MEN is undoubted but many of their basic features remain to be studied. In this study, we used ultra-fast neuroimaging to record activity of primary cultured myenteric neurons of guinea pig and human intestine after von Frey hair evoked deformation of neurites and somata. Independent component analysis was applied to reconstruct neuronal morphology and follow neuronal signals. Of the cultured neurons 45% (114 out of 256, 30 guinea pigs responded to neurite probing with a burst spike frequency of 13.4 Hz. Action potentials generated at the stimulation site invaded the soma and other neurites. Mechanosensitive sites were expressed across large areas of neurites. Many mechanosensitive neurites appeared to have afferent and efferent functions as those that responded to deformation also conducted spikes coming from the soma. Mechanosensitive neurites were also activated by nicotine application. This supported the concept of multifunctional MEN. 14% of the neurons (13 out of 96, 18 guinea pigs responded to soma deformation with burst spike discharge of 17.9 Hz. Firing of MEN adapted rapidly (RAMEN, slowly (SAMEN or ultra-slowly (USAMEN. The majority of MEN showed SAMEN behavior although significantly more RAMEN occurred after neurite probing. Cultured myenteric neurons from human intestine had similar properties. Compared to MEN, dorsal root ganglion neurons were activated by neurite but not by soma deformation with slow adaptation of firing. We demonstrated that MEN exhibit specific features very likely reflecting adaptation to their specialized functions in the gut.

  20. Measurement of the uniaxial mechanical properties of rat skin using different stress-strain definitions.

    Science.gov (United States)

    Karimi, A; Navidbakhsh, M

    2015-05-01

    The mechanical properties of skin tissue may vary according to the anatomical locations of a body. There are different stress-strain definitions to measure the mechanical properties of skin tissue. However, there is no agreement as to which stress-strain definition should be implemented to measure the mechanical properties of skin at different anatomical locations. Three stress definitions (second Piola-Kichhoff stress, engineering stress, and true stress) and four strain definitions (Almansi-Hamel strain, Green-St. Venant strain, engineering strain, and true strain) are employed to determine the mechanical properties of skin tissue at back and abdomen locations of a rat body. The back and abdomen skins of eight rats are excised and subjected to a series of tensile tests. The elastic modulus, maximum stress, and strain of skin tissues are measured using three stress definitions and four strain definitions. The results show that the effect of varying the stress definition on the maximum stress measurements of the back skin is significant but not when calculating the elastic modulus and maximum strain. No significant effects are observed on the elastic modulus, maximum stress, and strain measurements of abdomen skin by varying the stress definition. In the true stress-strain diagram, the maximum stress (20%), and elastic modulus (35%) of back skin are significantly higher than that of abdomen skin. The true stress-strain definition is favored to measure the mechanical properties of skin tissue since it gives more accurate measurements of the skin's response using the instantaneous values. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  1. Determining the stress field in active volcanoes using focal mechanisms

    Directory of Open Access Journals (Sweden)

    Bruno Massa

    2016-11-01

    Full Text Available Stress inversion of seismological datasets became an essential tool to retrieve the stress field of active tectonics and volcanic areas. In particular, in volcanic areas, it is able to put constrains on volcano-tectonics and in general in a better understanding of the volcano dynamics. During the last decades, a wide range of stress inversion techniques has been proposed, some of them specifically conceived to manage seismological datasets. A modern technique of stress inversion, the BRTM, has been applied to seismological datasets available at three different regions of active volcanism: Mt. Somma-Vesuvius (197 Fault Plane Solutions, FPSs, Campi Flegrei (217 FPSs and Long Valley Caldera (38,000 FPSs. The key role of stress inversion techniques in the analysis of the volcano dynamics has been critically discussed. A particular emphasis was devoted to performances of the BRTM applied to volcanic areas.

  2. Determining the stress field in active volcanoes using focal mechanisms

    Science.gov (United States)

    Massa, Bruno; D'Auria, Luca; Cristiano, Elena; De Matteo, Ada

    2016-11-01

    Stress inversion of seismological datasets became an essential tool to retrieve the stress field of active tectonics and volcanic areas. In particular, in volcanic areas, it is able to put constrains on volcano-tectonics and in general in a better understanding of the volcano dynamics. During the last decades, a wide range of stress inversion techniques has been proposed, some of them specifically conceived to manage seismological datasets. A modern technique of stress inversion, the BRTM, has been applied to seismological datasets available at three different regions of active volcanism: Mt. Somma-Vesuvius (197 Fault Plane Solutions, FPSs), Campi Flegrei (217 FPSs) and Long Valley Caldera (38,000 FPSs). The key role of stress inversion techniques in the analysis of the volcano dynamics has been critically discussed. A particular emphasis was devoted to performances of the BRTM applied to volcanic areas.

  3. Earthquakes focal mechanism and stress field pattern in the northeastern part of Egypt

    Directory of Open Access Journals (Sweden)

    Emad K. Mohamed

    2015-12-01

    The inversion technique scheme is used also in the present study for determining the regional stress field parameters for earthquake focal mechanism solutions based on the grid search method of Gephart and Forsyth (1984. The Results of the stress tensor using focal mechanisms of recent earthquakes show a prevailed tension stress field in N52°E, N41°E and N52°E for the northern Red Sea, Gulf of Suez and Gulf of Aqaba zone respectively.

  4. Mechanisms Underlying Stress Fracture and the Influence of Sex and Race/Ethnicity

    Science.gov (United States)

    2017-10-01

    AWARD NUMBER: W81XWH-16-1-0652 TITLE: Mechanisms Underlying Stress Fracture and the Influence of Sex and Race/Ethnicity PRINCIPAL INVESTIGATOR...5a. CONTRACT NUMBER W81XWH-16-1-0652 Mechanisms Underlying Stress Fracture and the Influence of Sex and Race/Ethnicity 5b. GRANT NUMBER W81XWH...to stress fracture risk. In particular, in Study 1, we will perform advanced skeletal imaging along with gait-assessments in subjects with history of

  5. A Model for Sustainable Building Energy Efficiency Retrofit (BEER) Using Energy Performance Contracting (EPC) Mechanism for Hotel Buildings in China

    Science.gov (United States)

    Xu, Pengpeng

    Hotel building is one of the high-energy-consuming building types, and retrofitting hotel buildings is an untapped solution to help cut carbon emissions contributing towards sustainable development. Energy Performance Contracting (EPC) has been promulgated as a market mechanism for the delivery of energy efficiency projects. EPC mechanism has been introduced into China relatively recently, and it has not been implemented successfully in building energy efficiency retrofit projects. The aim of this research is to develop a model for achieving the sustainability of Building Energy Efficiency Retrofit (BEER) in hotel buildings under the Energy Performance Contracting (EPC) mechanism. The objectives include: • To identify a set of Key Performance Indicators (KPIs) for measuring the sustainability of BEER in hotel buildings; • To identify Critical Success Factors (CSFs) under EPC mechanism that have a strong correlation with sustainable BEER project; • To develop a model explaining the relationships between the CSFs and the sustainability performance of BEER in hotel building. Literature reviews revealed the essence of sustainable BEER and EPC, which help to develop a conceptual framework for analyzing sustainable BEER under EPC mechanism in hotel buildings. 11 potential KPIs for sustainable BEER and 28 success factors of EPC were selected based on the developed framework. A questionnaire survey was conducted to ascertain the importance of selected performance indicators and success factors. Fuzzy set theory was adopted in identifying the KPIs. Six KPIs were identified from the 11 selected performance indicators. Through a questionnaire survey, out of the 28 success factors, 21 Critical Success Factors (CSFs) were also indentified. Using the factor analysis technique, the 21 identified CSFs in this study were grouped into six clusters to help explain project success of sustainable BEER. Finally, AHP/ANP approach was used in this research to develop a model to

  6. Is the microscopic stress computed from molecular simulations in mechanical equilibrium?

    Science.gov (United States)

    Torres-Sánchez, Alejandro; Vanegas, Juan M.; Arroyo, Marino

    The microscopic stress field connects atomistic simulations with the mechanics of materials at the nano-scale through statistical mechanics. However, its definition remains ambiguous. In a recent work we showed that this is not only a theoretical problem, but rather that it greatly affects local stress calculations from molecular simulations. We find that popular definitions of the local stress, which are continuously being employed to understand the mechanics of various systems at the nanoscale, violate the continuum statements of mechanical equilibrium. We exemplify these facts in local stress calculations of defective graphene, lipid bilayers, and fibrous proteins. Furthermore, we propose a new physical and sound definition of the microscopic stress that satisfies the continuum equations of balance, irrespective of the many-body nature of the inter-atomic potential. Thus, our proposal provides an unambiguous link between discrete-particle models and continuum mechanics at the nanoscale.

  7. Mechanisms of ER Stress-Mediated Mitochondrial Membrane Permeabilization.

    LENUS (Irish Health Repository)

    Gupta, Sanjeev

    2010-01-01

    During apoptosis, the process of mitochondrial outer membrane permeabilization (MOMP) represents a point-of-no-return as it commits the cell to death. Here we have assessed the role of caspases, Bcl-2 family members and the mitochondrial permeability transition pore on ER stress-induced MOMP and subsequent cell death. Induction of ER stress leads to upregulation of several genes such as Grp78, Edem1, Erp72, Atf4, Wars, Herp, p58ipk, and ERdj4 and leads to caspase activation, release of mitochondrial intermembrane proteins and dissipation of mitochondrial transmembrane potential (DeltaPsim). Mouse embryonic fibroblasts (MEFs) from caspase-9, -2 and, -3 knock-out mice were resistant to ER stress-induced apoptosis which correlated with decreased processing of pro-caspase-3 and -9. Furthermore, pretreatment of cells with caspase inhibitors (Boc-D.fmk and DEVD.fmk) attenuated ER stress-induced loss of DeltaPsim. However, only deficiency of caspase-9 and -2 could prevent ER stress-mediated loss of DeltaPsim. Bcl-2 overexpression or pretreatment of cells with the cell permeable BH4 domain (BH4-Tat) or the mitochondrial permeability transition pore inhibitors, bongkrekic acid or cyclosporine A, attenuated the ER stress-induced loss of DeltaPsim. These data suggest a role for caspase-9 and -2, Bcl-2 family members and the mitochondrial permeability transition pore in loss of mitochondrial membrane potential during ER stress-induced apoptosis.

  8. Catecholamines in stress: molecular mechanisms of gene expression.

    Science.gov (United States)

    Sabban, Esther L

    2007-06-01

    The catecholamines play key roles in orchestrating the response to stress. While this is crucial to handle emergency situations, stress becomes maladaptive when prolonged or repeated, increasing allosteric load and susceptibility to a wide range of serious diseases. The time frame of the regulation of gene expression, especially as it relates to catecholamine (CA) biosynthetic enzymes are compared in three crucial catecholaminergic locations, the adrenal medulla, sympathetic ganglia and locus coeruleus in male animals. The adrenal medulla displays very rapid response to stress and gene profiling reveals a wide repertoire of target genes, many of them activated by single and not by repeated stress. In contrast to the adrenal medulla, the sympathetic ganglia are especially responsive to activation of the HPA axis, and ACTH may have a direct effect. The locus coeruleus, origin of most of the noradrenergic neurons innervating much of the brain, displays activation of additional signalling pathways and transcription factor with repeated compared to single exposure to stress. Most of the studies have been performed in males. However, there is considerable evidence that females respond differently to stress. Estradiol can regulate TH, DBH and GTPCH gene expression, as well as to modulate its response to other second messenger such as cAMP. Prior treatment with estradiol was found to alter the response of CA biosynthetic enzymes to stress. This emphasizes the tissue and sex specific features of the mechanistic underpinning of the adaptation or maladaptation of the catecholaminergic systems to stress and provides the basis for specific interventions. Key words: Adrenal medulla - Catecholamine biosynthesis - Estrogen - Sympathetic ganglia - Locus coeruleus - Stress - Transcription factors.

  9. Structural and Mechanical Characterization of Sustainable Composites Based on Recycled and Stabilized Fly Ash

    Directory of Open Access Journals (Sweden)

    Stefano Besco

    2014-08-01

    Full Text Available This paper reports the results on the use of an innovative inert, based on stabilized fly ash from municipal solid waste incineration as a filler for polypropylene. The starting material, which contains large quantities of leachable Pb and Zn, was stabilized by means of an innovative process using rice husk ash as a waste silica source, together with other fly ashes, such as coal fly ash and flue gas desulfurization residues. The use of all waste materials to obtain a new filler makes the proposed technology extremely sustainable and competitive. The new composites, obtained by using the stabilized material as a filler for polypropylene, were characterized and their mechanical properties were also investigated. A comparison with a traditional polypropylene and calcium carbonate based compound was also done. This research activity was realized in the frame of the COSMOS-RICE project, financed by the EU Commission.

  10. Potentiality of Soybean Proteomics in Untying the Mechanism of Flood and Drought Stress Tolerance

    Directory of Open Access Journals (Sweden)

    Zahed Hossain

    2014-03-01

    Full Text Available Dissecting molecular pathways at protein level is essential for comprehensive understanding of plant stress response mechanism. Like other legume crops, soybean, the world’s most widely grown seed legume and an inexpensive source of protein and vegetable oil, is also extremely sensitive to abiotic stressors including flood and drought. Irrespective of the kind and severity of the water stress, soybean exhibits a tight control over the carbon metabolism to meet the cells required energy demand for alleviating stress effects. The present review summarizes the major proteomic findings related to changes in soybean proteomes in response to flood and drought stresses to get a clear insight into the complex mechanisms of stress tolerance. Furthermore, advantages and disadvantages of different protein extraction protocols and challenges and future prospects of soybean proteome study are discussed in detail to comprehend the underlying mechanism of water stress acclimation.

  11. Potentiality of Soybean Proteomics in Untying the Mechanism of Flood and Drought Stress Tolerance.

    Science.gov (United States)

    Hossain, Zahed; Komatsu, Setsuko

    2014-03-07

    Dissecting molecular pathways at protein level is essential for comprehensive understanding of plant stress response mechanism. Like other legume crops, soybean, the world's most widely grown seed legume and an inexpensive source of protein and vegetable oil, is also extremely sensitive to abiotic stressors including flood and drought. Irrespective of the kind and severity of the water stress, soybean exhibits a tight control over the carbon metabolism to meet the cells required energy demand for alleviating stress effects. The present review summarizes the major proteomic findings related to changes in soybean proteomes in response to flood and drought stresses to get a clear insight into the complex mechanisms of stress tolerance. Furthermore, advantages and disadvantages of different protein extraction protocols and challenges and future prospects of soybean proteome study are discussed in detail to comprehend the underlying mechanism of water stress acclimation.

  12. Potentiality of Soybean Proteomics in Untying the Mechanism of Flood and Drought Stress Tolerance

    Science.gov (United States)

    Hossain, Zahed; Komatsu, Setsuko

    2014-01-01

    Dissecting molecular pathways at protein level is essential for comprehensive understanding of plant stress response mechanism. Like other legume crops, soybean, the world’s most widely grown seed legume and an inexpensive source of protein and vegetable oil, is also extremely sensitive to abiotic stressors including flood and drought. Irrespective of the kind and severity of the water stress, soybean exhibits a tight control over the carbon metabolism to meet the cells required energy demand for alleviating stress effects. The present review summarizes the major proteomic findings related to changes in soybean proteomes in response to flood and drought stresses to get a clear insight into the complex mechanisms of stress tolerance. Furthermore, advantages and disadvantages of different protein extraction protocols and challenges and future prospects of soybean proteome study are discussed in detail to comprehend the underlying mechanism of water stress acclimation. PMID:28250373

  13. Volume Fraction Optimization of Functionally Graded Composite Plates for Stress Reduction and Thermo-Mechanical Buckling

    Science.gov (United States)

    Na, Kyung-Su; Kim, Ji-Hwan

    2008-02-01

    The volume fraction optimization of Functionally Graded Material (FGM) composite plate is investigated for stress reduction and thermo-mechanical buckling. Material properties are assumed to be temperature dependent and varied continuously in the thickness direction. The 3-D finite element is adopted using an 18-node solid element to analyze the plate model more accurately for the variation of material properties and temperature field in the thickness direction. Tensile and compressive stress ratios of the structure under mechanical load are evaluated for stress analysis. Temperature at each node is obtained by solving the steady-state heat transfer problem in the thermo-mechanical buckling analysis, and Newton-Raphson method is used for nonlinear analysis. Tensile stress ratios, compressive stress ratios and critical temperatures are analyzed for various thickness ratios and volume fraction distributions in the numerical study. Finally, the optimal design of FGM composite plate is investigated by considering the stress and the critical temperature.

  14. Translating the "Banana Genome" to Delineate Stress Resistance, Dwarfing, Parthenocarpy and Mechanisms of Fruit Ripening.

    Science.gov (United States)

    Dash, Prasanta K; Rai, Rhitu

    2016-01-01

    Evolutionary frozen, genetically sterile and globally iconic fruit "Banana" remained untouched by the green revolution and, as of today, researchers face intrinsic impediments for its varietal improvement. Recently, this wonder crop entered the genomics era with decoding of structural genome of double haploid Pahang (AA genome constitution) genotype of Musa acuminata. Its complex genome decoded by hybrid sequencing strategies revealed panoply of genes and transcription factors involved in the process of sucrose conversion that imparts sweetness to its fruit. Historically, banana has faced the wrath of pandemic bacterial, fungal, and viral diseases and multitude of abiotic stresses that has ruined the livelihood of small/marginal farmers' and destroyed commercial plantations. Decoding structural genome of this climacteric fruit has given impetus to a deeper understanding of the repertoire of genes involved in disease resistance, understanding the mechanism of dwarfing to develop an ideal plant type, unraveling the process of parthenocarpy, and fruit ripening for better fruit quality. Further, injunction of comparative genomics will usher in integration of information from its decoded genome and other monocots into field applications in banana related but not limited to yield enhancement, food security, livelihood assurance, and energy sustainability. In this mini review, we discuss pre- and post-genomic discoveries and highlight accomplishments in structural genomics, genetic engineering and forward genetic accomplishments with an aim to target genes and transcription factors for translational research in banana.

  15. Relaxation phenomena of electrical signal emissions from rock following application of abrupt mechanical stress

    Directory of Open Access Journals (Sweden)

    George Hloupis

    2012-04-01

    Full Text Available

    The emission of electrical signals during application of mechanical stress to brittle geo-materials (the so-called pressure-stimulated current; PSC can provide significant information regarding the mechanical status of a studied rock sample. PSCs originate as a result of the opening of cracks and microfractures in rock. In this study, such electrical signal emissions are detected and studied when rock samples are subjected to step-wise mechanical stress, increased from low stress levels vL up to higher stress levels vH. This increase is performed at high stress rates and consequently the stress is maintained practically constant for a long period. During this time, the applied stress reaches its maximum value, and the emitted PSC decays gradually and relaxes back to a minimum value. The conducted experiments suggest that the characteristics of the relaxation processes of the PSC depend directly on the high level of the applied stress that is maintained constant after the application of each stress step. Analysis of the macroscopic parameters that characterize the relaxation phenomenon of the PSC provides clear information regarding the proximity of the applied stress to the fracture limit of the rock sample.

  16. Green Concrete from Sustainable Recycled Coarse Aggregates: Mechanical and Durability Properties

    Directory of Open Access Journals (Sweden)

    Neeraj Jain

    2015-01-01

    Full Text Available Present investigations deal with the development of green concrete (M 30 grade using recycled coarse aggregates for sustainable development. Characterization of recycled coarse aggregates showed that physical and mechanical properties are of inferior quality and improvement in properties was observed after washing due to removal of old weak mortar adhered on its surface. The influence of natural coarse aggregates replacement (50 and 100% with recycled coarse aggregate on various mechanical and durability properties of hardened concrete were discussed and compared with controls at different w/c ratio. Improvements in all the engineering properties of hardened concrete were observed using washed recycled coarse aggregates. The compressive strength of 28-day hardened concrete containing 100% washed recycled aggregate was slightly lower (7% than concrete prepared with natural aggregates. Water absorption, carbonation, and rapid chloride penetration test were conducted to assess the durability of the concrete. Concrete was found moderately permeable for chloride ions penetration and no carbonation was observed in all the concrete mixes studied.

  17. Stress and Coping Mechanisms Among Breast Cancer Patients and ...

    African Journals Online (AJOL)

    Sitwala

    the leading cause of cancer mortality, representing. 14.1%. In Zambia, it is second to cervical cancer and its incidence is steadily increasing. A diagnosis of cancer regardless of stage is a stressful event impacting on all facets of the patient's life and that of her family caregivers. To minimize the impact, adaptive coping ...

  18. Induction of oxidative stress and antioxidative mechanisms in ...

    African Journals Online (AJOL)

    Relative to leaves, roots accumulated ~12-fold higher amounts of Zn. Oxidative stress markers, H2O2, malondialdehyde, ascorbate, proline, soluble sugars, putrescine and spermidine were elevated in both tissues, whereas, glutathione and spermine levels showed a steady decline. Total phenol increased in roots, but ...

  19. Contact mechanical analysis of O-ring stresses

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyung Kyu

    2007-02-15

    The purpose of this project is to develop the approximate solutions of contact traction and internal stress of an O-ring by using a two dimensional elasticity for enhancing the design and failure prediction technology. Investigated were the applicability of Lindley's formulae of contact force prediction and the Hertz theory. Three cases of O-ring installation were considered. The approximate solution of contact tractions and internal stresses of each case were derived. The key results are summarized as follows: 1. It is verified that Lindley's formulae predicts the relationship between the fractional compression and contact force. 2. In the case of Case I, II and III without internal pressure, it is found that a function form of the contact traction is the Hertzian. So it is possible to express the traction with a Hertzian form and correction factors. 3. The internal stresses are derived in the case of the Hertzian traction profile. The stresses at the center of O-ring show a satisfactory result when compared with the finite element result.

  20. Mechanically induced martensitic transformation as a stress driven process

    NARCIS (Netherlands)

    Geijselaers, Hubertus J.M.; Perdahcioglu, Emin Semih

    2009-01-01

    Combined shear-tension tests at room temperature performed on a 12Cr9Ni4Mo low carbon austenitic stainless steel have been reviewed and evaluated under the assumption that the martensitic transformation is exclusively stress driven. It is shown that the start of the transformation is very well

  1. What molecular mechanism is adapted by plants during salt stress ...

    African Journals Online (AJOL)

    Salt stress harmfully shocks agricultural yield throughout the world affecting production whether it is for subsistence or economic outcomes. The plant response to salinity consists of numerous processes that must function in coordination to alleviate both cellular hyper-osmolarity and ion disequilibrium. Salt tolerance and ...

  2. Influence of Rice Husk Ash on Mechanical Properties and Stress ...

    African Journals Online (AJOL)

    An attempt has been made in the investigation reported in this paper to study the influence of rice husk ash on the fresh, hardened properties and stress-strain behaviour of standard grade (M 30) SCC. Three SCC mixes with optimized quantities of mineral admixtures like fly ash(FA), ground granulated blast furnace slag ...

  3. Yielding to Stress: Recent Developments in Viscoplastic Fluid Mechanics

    Science.gov (United States)

    Balmforth, Neil J.; Frigaard, Ian A.; Ovarlez, Guillaume

    2014-01-01

    The archetypal feature of a viscoplastic fluid is its yield stress: If the material is not sufficiently stressed, it behaves like a solid, but once the yield stress is exceeded, the material flows like a fluid. Such behavior characterizes materials common in industries such as petroleum and chemical processing, cosmetics, and food processing and in geophysical fluid dynamics. The most common idealization of a viscoplastic fluid is the Bingham model, which has been widely used to rationalize experimental data, even though it is a crude oversimplification of true rheological behavior. The popularity of the model is in its apparent simplicity. Despite this, the sudden transition between solid-like behavior and flow introduces significant complications into the dynamics, which, as a result, has resisted much analysis. Over recent decades, theoretical developments, both analytical and computational, have provided a better understanding of the effect of the yield stress. Simultaneously, greater insight into the material behavior of real fluids has been afforded by advances in rheometry. These developments have primed us for a better understanding of the various applications in the natural and engineering sciences.

  4. Mechanisms of Nanoparticle-Induced Oxidative Stress and Toxicity

    Science.gov (United States)

    Wang, Liying

    2013-01-01

    The rapidly emerging field of nanotechnology has offered innovative discoveries in the medical, industrial, and consumer sectors. The unique physicochemical and electrical properties of engineered nanoparticles (NP) make them highly desirable in a variety of applications. However, these novel properties of NP are fraught with concerns for environmental and occupational exposure. Changes in structural and physicochemical properties of NP can lead to changes in biological activities including ROS generation, one of the most frequently reported NP-associated toxicities. Oxidative stress induced by engineered NP is due to acellular factors such as particle surface, size, composition, and presence of metals, while cellular responses such as mitochondrial respiration, NP-cell interaction, and immune cell activation are responsible for ROS-mediated damage. NP-induced oxidative stress responses are torch bearers for further pathophysiological effects including genotoxicity, inflammation, and fibrosis as demonstrated by activation of associated cell signaling pathways. Since oxidative stress is a key determinant of NP-induced injury, it is necessary to characterize the ROS response resulting from NP. Through physicochemical characterization and understanding of the multiple signaling cascades activated by NP-induced ROS, a systemic toxicity screen with oxidative stress as a predictive model for NP-induced injury can be developed. PMID:24027766

  5. The mechanisms behind stress: from populations to genes in nematodes

    NARCIS (Netherlands)

    Alda Alvarez, O.

    2006-01-01

    The increasing presence of abiotic stress factors in ecosystems over the past few decades has become an issue of major concern. The growing awareness of the detrimental effects that processes such as climatic change or chemical contamination can have on ecosystems and the species that inhabit them

  6. Methoxetamine produces rapid and sustained antidepressant effects probably via glutamatergic and serotonergic mechanisms.

    Science.gov (United States)

    Botanas, Chrislean Jun; Bryan de la Peña, June; Custodio, Raly James; Joy Dela Peña, Irene; Kim, Mikyung; Woo, Taeseon; Kim, Hee Jin; Kim, Hye In; Chang Cho, Min; Lee, Yong Sup; Cheong, Jae Hoon

    2017-11-01

    Depression afflicts around 16% of the world's population, making it one of the leading causes of disease burden worldwide. Despite a number of antidepressants available today, the delayed onset time and low remission rate of these treatments are still a major challenge. The N-methyl-D-aspartate (NMDA) receptor antagonist ketamine has shown to produce rapid and sustained antidepressant effects and has paved the way for a new generation of glutamate-based antidepressants. Methoxetamine (MXE) is a ketamine analogue that acts as an NMDA receptor antagonist and a serotonin reuptake inhibitor. However, no studies have evaluated the antidepressant effects of MXE. Here, we assessed whether MXE produces antidepressant effects and explored possible mechanisms underlying its effects. Mice were treated with MXE (2.5, 5, or 10 mg/kg) and their behavior was evaluated 30 min and 24 h later in an array of behavioral experiments used for screening antidepressant drugs. A separate group of mice were treated with NBQX, an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, or ketanserin, a 5HT2 receptor antagonist, before MXE (5 mg/kg) administration in the forced swimming test (FST). We also investigated the effect of MXE on glutamatergic- and serotonergic-related genes in the mouse hippocampus using quantitative real-time PCR. MXE produced antidepressant effects 30 min after treatment that persisted for 24 h. Both NBQX and ketanserin blocked the antidepressant effects of MXE in the FST. MXE also altered hippocampal glutamatergic- and serotonergic gene expressions. These results suggest that MXE has rapid and sustained antidepressant effects, possibly mediated by the glutamatergic and serotonergic system. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Biological mechanisms of premature ovarian failure caused by psychological stress based on support vector regression

    OpenAIRE

    Wang, Xiu-feng; Zhang, Lei; Wu, Qing-hua; Min, Jian-Xin; Ma, Na; Luo, Lai-Cheng

    2015-01-01

    Psychological stress has become a common and important cause of premature ovarian failure (POF). Therefore, it is very important to explore the mechanisms of POF resulting from psychological stress. Sixty SD rats were randomly divided into control and model groups. Biomolecules associated with POF (β-EP, IL-1, NOS, NO, GnRH, CRH, FSH, LH, E2, P, ACTH, and CORT) were measured in the control and psychologically stressed rats. The regulation relationships of the biomolecules were explored in the...

  8. Thermal mechanical stress modeling of GCtM seals

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Steve Xunhu [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Chambers, Robert [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    Finite-element thermal stress modeling at the glass-ceramic to metal (GCtM) interface was conducted assuming heterogeneous glass-ceramic microstructure. The glass-ceramics were treated as composites consisting of high expansion silica crystalline phases dispersed in a uniform residual glass. Interfacial stresses were examined for two types of glass-ceramics. One was designated as SL16 glass -ceramic, owing to its step-like thermal strain curve with an overall coefficient of thermal expansion (CTE) at 16 ppm/ºC. Clustered Cristobalite is the dominant silica phase in SL16 glass-ceramic. The other, designated as NL16 glass-ceramic, exhibited clusters of mixed Cristobalite and Quartz and showed a near-linear thermal strain curve with a same CTE value.

  9. Adaptive translation as a mechanism of stress response and adaptation

    OpenAIRE

    Pan, Tao

    2013-01-01

    The composition of the cellular proteome is commonly thought to strictly adhere to the genetic code. However, accumulating evidence indicates that cells also regulate the synthesis of mutant protein molecules that deviate from the genetic code. Production of mutant proteins varies in amounts and specificity and generally occurs when cells are stressed or undergo environmental adaptation. The deliberate synthesis of protein mutants suggests that some of these proteins can be useful in cellular...

  10. Emotion Dysregulation as a Mechanism Linking Stress Exposure to Adolescent Aggressive Behavior

    Science.gov (United States)

    Herts, Kate L.; McLaughlin, Katie A.; Hatzenbuehler, Mark L.

    2012-01-01

    Exposure to stress is associated with a wide range of internalizing and externalizing problems in adolescents, including aggressive behavior. Extant research examining mechanisms underlying the associations between stress and youth aggression has consistently identified social information processing pathways that are disrupted by exposure to…

  11. Mechanisms of Stress Resistance and Gene Regulation in the Radioresistant Bacterium Deinococcus radiodurans.

    Science.gov (United States)

    Agapov, A A; Kulbachinskiy, A V

    2015-10-01

    The bacterium Deinococcus radiodurans reveals extraordinary resistance to ionizing radiation, oxidative stress, desiccation, and other damaging conditions. In this review, we consider the main molecular mechanisms underlying such resistance, including the action of specific DNA repair and antioxidation systems, and transcription regulation during the anti-stress response.

  12. Increased endoplasmic reticulum stress in mouse osteocytes with aging alters Cox-2 response to mechanical stimuli

    NARCIS (Netherlands)

    Chalil, S.; Jaspers, R.T.; Manders, R.J.; Klein-Nulend, J.; Bakker, A.D.; Deldicque, L.

    2015-01-01

    Aging reduces bone mass as well as the anabolic response of bone to mechanical stimuli, resulting in osteopenia. Endoplasmic reticulum (ER) stress impairs the response of myogenic cells to anabolic stimuli, and is involved in sarcopenia, but whether ER stress also contributes to osteopenia is

  13. An Integrated Review of Psychological Stress in Parkinson's Disease: Biological Mechanisms and Symptom and Health Outcomes

    Science.gov (United States)

    2016-01-01

    Parkinson's disease (PD) is characterized by complex symptoms and medication-induced motor complications that fluctuate in onset, severity, responsiveness to treatment, and disability. The unpredictable and debilitating nature of PD and the inability to halt or slow disease progression may result in psychological stress. Psychological stress may exacerbate biological mechanisms believed to contribute to neuronal loss in PD and lead to poorer symptom and health outcomes. The purpose of this integrated review is to summarize and appraise animal and human research studies focused on biological mechanisms, symptom, and health outcomes of psychological stress in PD. A search of the electronic databases PubMed/Medline and CINAHL from 1980 to the present using the key words Parkinson's disease and stress, psychological stress, mental stress, and chronic stress resulted in 11 articles that met inclusion criteria. The results revealed significant associations between psychological stress and increased motor symptom severity and loss of dopamine-producing neurons in animal models of PD and between psychological stress and increased symptom severity and poorer health outcomes in human subjects with PD. Further research is needed to fully elucidate the underlying biological mechanisms responsible for these relationships, for the ultimate purpose of designing targeted interventions that may modify the disease trajectory. PMID:28058129

  14. Mechanisms of silicon-mediated alleviation of drought and salt stress in plants: a review.

    Science.gov (United States)

    Rizwan, Muhammad; Ali, Shafaqat; Ibrahim, Muhammad; Farid, Mujahid; Adrees, Muhammad; Bharwana, Saima Aslam; Zia-Ur-Rehman, Muhammad; Qayyum, Muhammad Farooq; Abbas, Farhat

    2015-10-01

    Drought and salinity are the main abiotic stresses limiting crop yield and quality worldwide. Improving food production in drought- and salt-prone areas is the key to meet the increasing food demands in near future. It has been widely reported that silicon (Si), a second most abundant element in soil, could reduce drought and salt stress in plants. Here, we reviewed the emerging role of Si in enhancing drought and salt tolerance in plants and highlighted the mechanisms through which Si could alleviate both drought and salt stress in plants. Silicon application increased plant growth, biomass, photosynthetic pigments, straw and grain yield, and quality under either drought or salt stress. Under both salt and drought stress, the key mechanisms evoked are nutrient elements homeostasis, modification of gas exchange attributes, osmotic adjustment, regulating the synthesis of compatible solutes, stimulation of antioxidant enzymes, and gene expression in plants. In addition, Si application decreased Na(+) uptake and translocation while increased K(+) uptake and translocation under salt stress. However, these mechanisms vary with plant species, genotype, growth conditions, duration of stress imposed, and so on. This review article highlights the potential for improving plant resistance to drought and salt stress by Si application and provides a theoretical basis for application of Si in saline soils and arid and semiarid regions worldwide. This review article also highlights the future research needs about the role of Si under drought stress and in saline soils.

  15. Impaired Functional Connectivity in the Prefrontal Cortex: A Mechanism for Chronic Stress-Induced Neuropsychiatric Disorders

    Directory of Open Access Journals (Sweden)

    Ignacio Negrón-Oyarzo

    2016-01-01

    Full Text Available Chronic stress-related psychiatric diseases, such as major depression, posttraumatic stress disorder, and schizophrenia, are characterized by a maladaptive organization of behavioral responses that strongly affect the well-being of patients. Current evidence suggests that a functional impairment of the prefrontal cortex (PFC is implicated in the pathophysiology of these diseases. Therefore, chronic stress may impair PFC functions required for the adaptive orchestration of behavioral responses. In the present review, we integrate evidence obtained from cognitive neuroscience with neurophysiological research with animal models, to put forward a hypothesis that addresses stress-induced behavioral dysfunctions observed in stress-related neuropsychiatric disorders. We propose that chronic stress impairs mechanisms involved in neuronal functional connectivity in the PFC that are required for the formation of adaptive representations for the execution of adaptive behavioral responses. These considerations could be particularly relevant for understanding the pathophysiology of chronic stress-related neuropsychiatric disorders.

  16. Microseismicity derived fault-planes and their relationship to focal mechanism, stress inversion, and geologic data

    Science.gov (United States)

    Urbancic, Theodore I.; Trifu, Cezar-Ioan; Young, R. Paul

    1993-11-01

    General stress and faulting trends have been retrieved through the analysis of mining induced microseismic events (M less than 0) at two sites, related to an m(sub N) 2.6 rockburst, and an excavation at depth. A comparison of results obtained through principal component analysis (PCA) of seismicity, focal mechanism, and stress inversion, with in-situ measurements of stress and structural mapping data, show that: under stable stress conditions, the P, B, T, and stress inversion axes are consistent with in-situ measurements of stresses; stress inversion and PCA fault-planes lie within 10 to 20 deg of the most significant mapped features at the sites; and the PCA technique provides a robust approach for the determination of fault-planes.

  17. NSAIDS and the Osteogenic Response to Mechanical Stress in Premenopausal Women

    National Research Council Canada - National Science Library

    Kohrt, Wendy M

    2004-01-01

    ...) use on the osteogenic response to 9 months of exercise training in 102 women. The scientific rationale for this study centers on the knowledge that the osteogenic response to mechanical stress is a prostaglandin (PG...

  18. Stress and PTSD Mechanisms as Targets for Pharmacotherapy of Alcohol Abuse, Addiction, and Relapse

    Science.gov (United States)

    2015-10-01

    AWARD NUMBER: W81XWH-13-1-0126 TITLE: Stress and PTSD Mechanisms as Targets for Pharmacotherapy of Alcohol Abuse, Addiction , and Relapse...DATES COVERED 30 Sep 2014 - 29 Sep 2015 4. TITLE AND SUBTITLE Stress and PTSD Mechanisms as Targets for Pharmacotherapy of Alcohol Abuse, Addiction ...system in pathological anxiety: a focus on panic with relevance to generalized anxiety and phobias. Biol Psychiatry 46:1205-18. Stevens DR

  19. The Lund University Checklist for Incipient Exhaustion: a prospective validation of the onset of sustained stress and exhaustion warnings.

    Science.gov (United States)

    Österberg, Kai; Persson, Roger; Viborg, Njördur; Jönsson, Peter; Tenenbaum, Artur

    2016-09-29

    The need for instruments that can assist in detecting the prodromal stages of stress-related exhaustion has been acknowledged. The aim of the present study was to evaluate whether the Lund University Checklist for Incipient Exhaustion (LUCIE) could accurately and prospectively detect the onset of incipient exhaustion and to what extent work stressor exposure and private burdens were associated with increasing LUCIE scores. Using surveys, 1355 employees were followed for 11 quarters. Participants with prospectively elevated LUCIE scores were targeted by three algorithms entailing 4 quarters: (1) abrupt onset to a sustained Stress Warning (n = 18), (2) gradual onset to a sustained Stress Warning (n = 42), and (3) sustained Exhaustion Warning (n = 36). The targeted participants' survey reports on changes in work situation and private life during the fulfillment of any algorithm criteria were analyzed, together with the interview data. Participants untargeted by the algorithms constituted a control group (n = 745). Eighty-seven percent of participants fulfilling any LUCIE algorithm criteria (LUCIE indication cases) rated a negative change in their work situation during the 4 quarters, compared to 48 % of controls. Ratings of negative changes in private life were also more common in the LUCIE indication groups than among controls (58 % vs. 29 %), but free-text commentaries revealed that almost half of the ratings in the LUCIE indication groups were due to work-to-family conflicts and health problems caused by excessive workload, assigned more properly to work-related negative changes. When excluding the themes related to work-stress-related private life compromises, negative private life changes in the LUCIE indication groups dropped from 58 to 32 %, while only a negligible drop from 29 to 26 % was observed among controls. In retrospective interviews, 79 % of the LUCIE indication participants confirmed exclusively/predominantly work stressors

  20. The Lund University Checklist for Incipient Exhaustion: a prospective validation of the onset of sustained stress and exhaustion warnings

    Directory of Open Access Journals (Sweden)

    Kai Österberg

    2016-09-01

    Full Text Available Abstract Background The need for instruments that can assist in detecting the prodromal stages of stress-related exhaustion has been acknowledged. The aim of the present study was to evaluate whether the Lund University Checklist for Incipient Exhaustion (LUCIE could accurately and prospectively detect the onset of incipient exhaustion and to what extent work stressor exposure and private burdens were associated with increasing LUCIE scores. Methods Using surveys, 1355 employees were followed for 11 quarters. Participants with prospectively elevated LUCIE scores were targeted by three algorithms entailing 4 quarters: (1 abrupt onset to a sustained Stress Warning (n = 18, (2 gradual onset to a sustained Stress Warning (n = 42, and (3 sustained Exhaustion Warning (n = 36. The targeted participants’ survey reports on changes in work situation and private life during the fulfillment of any algorithm criteria were analyzed, together with the interview data. Participants untargeted by the algorithms constituted a control group (n = 745. Results Eighty-seven percent of participants fulfilling any LUCIE algorithm criteria (LUCIE indication cases rated a negative change in their work situation during the 4 quarters, compared to 48 % of controls. Ratings of negative changes in private life were also more common in the LUCIE indication groups than among controls (58 % vs. 29 %, but free-text commentaries revealed that almost half of the ratings in the LUCIE indication groups were due to work-to-family conflicts and health problems caused by excessive workload, assigned more properly to work-related negative changes. When excluding the themes related to work-stress-related private life compromises, negative private life changes in the LUCIE indication groups dropped from 58 to 32 %, while only a negligible drop from 29 to 26 % was observed among controls. In retrospective interviews, 79 % of the LUCIE indication participants

  1. Work related stress and coping mechanisms among bankers in Lagos, Nigeria.

    Science.gov (United States)

    Olatona, F A; Ezeobika, E N; Okafor, I P; Owoeye, O B A

    2014-03-01

    This study assessed knowledge, prevalence, associated factors and mechanisms of coping with stress among bankers in Lagos State. It was a descriptive cross sectional study. A two stage sampling technique was used to select two hundred and twenty seven (227) respondents. Data was collected using a structured self administered questionnaire. The analysis was done using Epi-info version 2002 software and Chi Square was used to determine association between variables at p value 0.05. Fischer's Exact test was used where Chi-square was not valid. The age range of respondents was between 20 and 49 years while the mean age was 31.3 +/- 5.0 years. Only 3.6% had good level of knowledge about stress, 42.2% had fair level while more than half of the respondents had poor level of knowledge about stress (54.3%). Majority (67.0%) of the respondents were moderately stressed while one quarter (24.7%) were highly stressed. Majority (92.4%) of the respondents used good coping mechanisms though 69.5% of the respondents also used bad coping mechanisms. A greater proportion of those who had poor knowledge about stress were stressed or highly stressed (p = 0.002). A statistically significant association was also found between the departments in the bank and level of stress of the respondents (p = 0.002). The prevalence of stress was high among the bank workers studied. It is recommended that effective stress management programmes are implemented to address the problem of stress among bank workers.

  2. Development and Validation of Mechanical Engineering Trade Skills Assessment Instrument for Sustainable Job Security in Yobe State

    Science.gov (United States)

    Adamu, Gishua Garba; Dawha, Josphine Musa; Kamar, Tiamiyu Salihu

    2015-01-01

    Mechanical Engineering Trade Skills Assessment Instrument (METSAI) is aimed at determining the extent to which students have acquired practical skills before graduation that will enable them get employment for sustainable job security in Yobe state. The study employed instrumentation research design. The populations of the study were 23 mechanical…

  3. Self-assembly of amphiphilic Janus dendrimers into mechanically robust supramolecular hydrogels for sustained drug release.

    Science.gov (United States)

    Nummelin, Sami; Liljeström, Ville; Saarikoski, Eve; Ropponen, Jarmo; Nykänen, Antti; Linko, Veikko; Seppälä, Jukka; Hirvonen, Jouni; Ikkala, Olli; Bimbo, Luis M; Kostiainen, Mauri A

    2015-10-05

    Compounds that can gelate aqueous solutions offer an intriguing toolbox to create functional hydrogel materials for biomedical applications. Amphiphilic Janus dendrimers with low molecular weights can readily form self-assembled fibers at very low mass proportion (0.2 wt %) to create supramolecular hydrogels (G'≫G'') with outstanding mechanical properties and storage modulus of G'>1000 Pa. The G' value and gel melting temperature can be tuned by modulating the position or number of hydrophobic alkyl chains in the dendrimer structure; thus enabling exquisite control over the mesoscale material properties in these molecular assemblies. The gels are formed within seconds by simple injection of ethanol-solvated dendrimers into an aqueous solution. Cryogenic TEM, small-angle X-ray scattering, and SEM were used to confirm the fibrous structure morphology of the gels. Furthermore, the gels can be efficiently loaded with different bioactive cargo, such as active enzymes, peptides, or small-molecule drugs, to be used for sustained release in drug delivery. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. An Independent Review and Accountability Mechanism for the Sustainable Development Goals

    Science.gov (United States)

    2016-01-01

    Abstract The Framework Convention on Global Health (FCGH), a proposed global treaty to be rooted in the right to health and aimed at health equity, could establish a nuanced, layered, and multi-faceted regime of compliance with, and accountability to, the right to health. In so doing, it would significantly strengthen accountability for the health-related Sustainable Development Goals (SDGs), which it would encompass. Legally binding, the FCGH could facilitate accountability through the courts and catalyze comprehensive domestic accountability regimes, requiring national strategies that include transparency, community and national mechanisms for accountability and participation and an enabling environment for social empowerment. A “Right to Health Capacity Fund” could ensure resources to implement these strategies. Inclusive national processes could establish targets, benchmarks, and indicators consistent with FCGH guidance, with regular reporting to a treaty body, which could also hear individual cases. State reports could be required to include plans to overcome implementation gaps, subjecting poorly complying states to penalties and targeted capacity building measures. Regional special rapporteurs could facilitate compliance through regular country visits, while also responding to serious violations. And reaching beyond government compliance, from capacity building to the courts and contractual obligations, the FCGH could establish nationally enforceable right to health obligations on the private sector. PMID:27781005

  5. Role and mechanism of endoplasmic reticulum stress and Ca2+ overload in pulmonary endothelial cell damage induced by heat stress

    Directory of Open Access Journals (Sweden)

    Bao-jun YU

    2017-08-01

    Full Text Available Objective To observe the effect of different temperatures on endoplasmic reticulum stress, calcium overload, mitochondria and cell damage in pulmonary microvascular endothelial cells (PMVEC induced by heat stress, and clarify the mechanism of endothelial cell injury in the process of heat stress to provide experimental basis for clinical prevention and treatment of heat stree. Methods Heat stress model of PMVEC cell was set up. Control group cells were incubated at 37℃, 5%CO2, while heat stress group cells were incubated at 39℃, 41℃, 43℃ for 2h, respectively, then further incubated at 37℃, 5%CO2 for 6h. Pretreatment of cells with 20μmol/L BAPTA-AM or 50μmol/L CsA before heat stress at 43℃. The protein levels of p-PERK, PERK p-eIF2a, eIF2a, ATF4 and GRP78 were analyzed by Western blotting. Intracellular Ca2+, mitochondrial membrane potential and the changes in mitochondrial permeability transition pore were investigated by flow cytometry. The change of caspase-3 was detected by Caspase Assay Kit. Millicell-ERS Volt-Ohm Meter and Accessories was used for determining the changes of transepithelium electrical resistance (TER. Results Compared with the control group, with the increase of heat stress temperature (41-43℃, the phosphorylation of p-PERK and p-eIF2a protein and the expressions of ATF4 and GRP78 proteins were gradually activated, intracellular Ca2+ increased, MPTP pore was opened, mitochondrial membrane potential decreased, cell permeability increased and apoptosis occurred, and it was the most obvious in the 43℃ heat stress group, and the difference was statistically significant (P<0.05. Pretreatment with Ca2+ inhibitors promoted the recovery of the MPTP hole, mitochondrial membrane potential and cell permeability, and reduced the occurrence of apoptosis. While pretreatment with the mitochondrial protective agent did not reduce the release of Ca2+, but it could promote the recovery of cell permeability and reduce the

  6. Sustainability in Agricultural Mechanization: Assessment of a Combined Photovoltaic and Electric Multipurpose System for Farmers

    Directory of Open Access Journals (Sweden)

    Toufic El Asmar

    2009-11-01

    Full Text Available This study is dedicated to the assessment of the possibility of replacing fossil fuels with renewable energy as a source of power in modern agriculture. We examined the use of a completely sustainable agricultural mechanization system based on a renewable energy system and a battery powered, multi-purpose agricultural vehicle. This assessment is based on the RAMseS project, financed by the European Commission under the 6th Framework Program, which has led to the actual manufacturing of the system, at present being tested in Lebanon. In the present study, we assess the environmental and economic performance of the RAMseS system. We evaluate the external costs by means of a specific model that takes into account the life-cycle cost (LCC, economical indexes, and life-cycle emissions for the vehicle during its life span. The results are compared with those of a standard vehicle based on the internal combustion engine (ICEV. The results show that the RAMseS system can avoid the emission of about 23 ton of CO2equ per year. The life cycle cost (LCC assessment using MATLAB software shows that the LCC for the RAMseS vehicle and the ICEV are the same for a fuel unit price (pf of 1.45 €/L. Finally, we show that almost 52 % of the RAMseS LCC is due to the batteries of the electric vehicle. A 50% decrease in batteries unit cost would cause the LCC of two system to be the same at a fuel cost of 0.8 €/L. The final result is that the RAMseS system remains—at present— marginally more expensive than an equivalent system based on conventional fuels and internal combustion engines. Nevertheless, with the gradual depletion of fossil fuels, all electric agricultural mechanized system provide an alternative solution that is dependent only on renewable energy and recyclable resources.

  7. The effect of fluid mechanical stress on cellular arachidonic acid metabolism

    Science.gov (United States)

    Mcintire, L. V.; Frangos, J. A.; Rhee, B. G.; Eskin, S. G.; Hall, E. R.

    1987-01-01

    The effect of sublytic levels of mechanical perturations of cells on cell metabolism were investigated by analyzing the products of arachidonic acid (used as a marker metabolite) in blood platelets, polymorphonuclear leucocytes, and cultured umbilical-vein endothelial cells after the suspensions of these cells were subjected to a shear stress in a modified viscometer. It is shown that the sublytic levels of mechanical stress stimulated the arachidonic acid metabolism in all these cell types. Possible biological implications of this stress-metabolism coupling are discussed.

  8. Perceived Stress, Stressors, and Coping Mechanisms among Doctor of Pharmacy Students

    Directory of Open Access Journals (Sweden)

    Jennifer W. Beall

    2015-11-01

    Full Text Available The primary purpose of this study was to examine perceived stress in doctor of pharmacy students during their first, second, and third years of their program in a fully implemented new curriculum. The secondary objectives were to determine if there is a relationship between perceived stress and certain demographic variables, to compare student pharmacist perceived stress to the perceived stress in the general population, and to examine student reported stressors during pharmacy school and coping strategies employed for those stressors. A previously validated survey (Perceived Stress Scale-10 was given to first, second, and third year student pharmacists. Females exhibited higher mean stress scores than males. The under 22 years and over 32 years age categories exhibited higher mean stress scores than the 22 to 26 year old student population. There was no significant difference in perceived stress scores between classes of the program. Only a portion of the variation in stress scores was predicted by gender, age, marital status, race, and year in curriculum. Stress scores among these student pharmacists are higher overall than those in previously published probability samples in the general population. Class assignments and completing electronic portfolios were the top stressors reported. Spending time with family and friends was the most frequent coping mechanism reported. Programming related to stress reduction (particularly among female and nontraditional age students appears warranted.

  9. Perceived Stress, Stressors, and Coping Mechanisms among Doctor of Pharmacy Students.

    Science.gov (United States)

    Beall, Jennifer W; DeHart, Renee M; Riggs, Robert M; Hensley, John

    2015-11-25

    The primary purpose of this study was to examine perceived stress in doctor of pharmacy students during their first, second, and third years of their program in a fully implemented new curriculum. The secondary objectives were to determine if there is a relationship between perceived stress and certain demographic variables, to compare student pharmacist perceived stress to the perceived stress in the general population, and to examine student reported stressors during pharmacy school and coping strategies employed for those stressors. A previously validated survey (Perceived Stress Scale-10) was given to first, second, and third year student pharmacists. Females exhibited higher mean stress scores than males. The under 22 years and over 32 years age categories exhibited higher mean stress scores than the 22 to 26 year old student population. There was no significant difference in perceived stress scores between classes of the program. Only a portion of the variation in stress scores was predicted by gender, age, marital status, race, and year in curriculum. Stress scores among these student pharmacists are higher overall than those in previously published probability samples in the general population. Class assignments and completing electronic portfolios were the top stressors reported. Spending time with family and friends was the most frequent coping mechanism reported. Programming related to stress reduction (particularly among female and nontraditional age students) appears warranted.

  10. Stress-restress evokes sustained iNOS activity and altered GABA levels and NMDA receptors in rat hippocampus

    DEFF Research Database (Denmark)

    Harvey, Brian H; Oosthuizen, Frasia; Brand, Linda

    2004-01-01

    RATIONALE: Stress-related glucocorticoid and glutamate release have been implicated in hippocampal atrophy evident in patients with post-traumatic stress disorder (PTSD). Glutamatergic mechanisms activate nitric oxide synthase (NOS), while gamma-amino-butyric acid (GABA) may inhibit both...... glutamatergic and nitrergic transmission. Animal studies support a role for NOS in stress. OBJECTIVES: We have studied the role of NOS and glucocorticoids, as well as inhibitory and excitatory transmitters, in a putative animal model of PTSD that emphasizes repeated trauma. METHODS: Hippocampal NOS activity, N......-methyl-D-aspartate (NMDA) receptor binding characteristics and GABA levels were studied in Sprague-Dawley rats 21 days after exposure to a stress-restress paradigm, using radiometric analysis, radioligand studies and high-performance liquid chromatography (HPLC) analysis with electrochemical detection, respectively...

  11. Aetiology and mechanisms of injury in medial tibial stress syndrome: Current and future developments

    OpenAIRE

    Franklyn, Melanie; Oakes, Barry

    2015-01-01

    Medial tibial stress syndrome (MTSS) is a debilitating overuse injury of the tibia sustained by individuals who perform recurrent impact exercise such as athletes and military recruits. Characterised by diffuse tibial anteromedial or posteromedial surface subcutaneous periostitis, in most cases it is also an injury involving underlying cortical bone microtrauma, although it is not clear if the soft tissue or cortical bone reaction occurs first. Nuclear bone scans and magnetic resonance imagin...

  12. A cross-sectional study of the effects of load carriage on running characteristics and tibial mechanical stress: implications for stress fracture injuries in women

    Science.gov (United States)

    2017-03-23

    effects of load carriage on running characteristics and tibial mechanical stress : implications for stress -fracture injuries in women Chun Xu1, Amy Silder2...Ju Zhang3, Jaques Reifman1* and Ginu Unnikrishnan1Abstract Background: Load carriage is associated with musculoskeletal injuries, such as stress ...kinematics and kinetics of the body, as well as the tibial mechanical stress during running. We also compared the biomechanics of walking (studied

  13. Mechanical stress regulates insulin sensitivity through integrin-dependent control of insulin receptor localization.

    Science.gov (United States)

    Kim, Jung; Bilder, David; Neufeld, Thomas P

    2018-01-15

    Insulin resistance, the failure to activate insulin signaling in the presence of ligand, leads to metabolic diseases, including type 2 diabetes. Physical activity and mechanical stress have been shown to protect against insulin resistance, but the molecular mechanisms remain unclear. Here, we address this relationship in the Drosophila larval fat body, an insulin-sensitive organ analogous to vertebrate adipose tissue and livers. We found that insulin signaling in Drosophila fat body cells is abolished in the absence of physical activity and mechanical stress even when excess insulin is present. Physical movement is required for insulin sensitivity in both intact larvae and fat bodies cultured ex vivo. Interestingly, the insulin receptor and other downstream components are recruited to the plasma membrane in response to mechanical stress, and this membrane localization is rapidly lost upon disruption of larval or tissue movement. Sensing of mechanical stimuli is mediated in part by integrins, whose activation is necessary and sufficient for mechanical stress-dependent insulin signaling. Insulin resistance develops naturally during the transition from the active larval stage to the immotile pupal stage, suggesting that regulation of insulin sensitivity by mechanical stress may help coordinate developmental programming with metabolism. © 2018 Kim et al.; Published by Cold Spring Harbor Laboratory Press.

  14. Cadherin-11 modulates cell morphology and collagen synthesis in periodontal ligament cells under mechanical stress.

    Science.gov (United States)

    Feng, Lishu; Zhang, Yimei; Kou, Xiaoxing; Yang, Ruili; Liu, Dawei; Wang, Xuedong; Song, Yang; Cao, Haifeng; He, Danqing; Gan, Yehua; Zhou, Yanheng

    2017-03-01

    To examine the role of cadherin-11, an integral membrane adhesion molecule, in periodontal ligament cells (PDLCs) under mechanical stimulation. Human PDLCs were cultured and subjected to mechanical stress. Cadherin-11 expression and cell morphology of PDLCs were investigated via immunofluorescence staining. The mRNA and protein expressions of cadherin-11 and type I collagen (Col-I) of PDLCs were evaluated by quantitative real-time polymerase chain reaction and Western blot, respectively. Small interfering RNA was used to knock down cadherin-11 expression in PDLCs. The collagen matrix of PDLCs was examined using toluidine blue staining. Cadherin-11 was expressed in PDLCs. Mechanical stress suppressed cadherin-11 expression in PDLCs with prolonged force treatment time and increased force intensity, accompanied by suppressed β-catenin expression. Simultaneously, mechanical stress altered cell morphology and repressed Col-I expression in a time- and dose-dependent manner in PDLCs. Moreover, knockdown of cadherin-11 with suppressed β-catenin expression resulted in altered PDLC morphology and repressed collagen expression, which were consistent with the changes observed under mechanical stress. Results of this study suggest that cadherin-11 is expressed in PDLCs and modulates PDLC morphology and collagen synthesis in response to mechanical stress, which may play an important role in the homeostasis and remodeling of the PDL under mechanical stimulation.

  15. Unraveling mechanisms of toxicant-induced oxidative stress in cardiovascular disease.

    Science.gov (United States)

    Dugas, Tammy R

    2018-02-01

    To date, numerous clinical studies examining correlations between oxidative stress biomarkers and cardiovascular diseases (CVD) have repeatedly suggested a role for oxidant injury in the pathogenesis of diseases such as atherosclerosis. Despite this, antioxidant supplementation trials have not demonstrated a reduction in disease progression. Nevertheless, small animal and epidemiological studies have linked exposures to certain toxicants with increased CVD risk involving putative oxidative stress mechanisms. A few prototypical vascular toxicants will be discussed as examples of toxicants that likely act via oxidative stress mechanisms. For discussion, we will classify these toxicants as those that induce direct (e.g., arsenic, nucleoside reverse transcriptase inhibitors) versus indirect (particulate matter, ozone) oxidative stress mechanisms, and those that likely induce CVD through both direct and indirect mechanisms (cigarette smoke). Finally, new findings in oxidative stress research, including the emerging importance of reactive sulfur species, hydrogen peroxide as a presumed endothelium-derived hyperpolarizing factors, etc., will be discussed, as well as the need to determine the role of toxicants in modulating these newly identified pathways. Moreover, given the lack of success in conclusively demonstrating the roles of oxidative stress in CVD risk stratification, research probing the roles of toxicant exposures in propagating CVD pathogenesis may be a novel approach for more conclusively delineating the causal role of oxidative stress in CVD initiation and progression.

  16. Mechanisms of silicon-mediated alleviation of abiotic stresses in higher plants: a review.

    Science.gov (United States)

    Liang, Yongchao; Sun, Wanchun; Zhu, Yong-Guan; Christie, Peter

    2007-05-01

    Although silicon (Si) is the second most abundant element both on the surface of the Earth's crust and in soils, it has not yet been listed among the essential elements for higher plants. However, the beneficial role of Si in stimulating the growth and development of many plant species has been generally recognized. Silicon is known to effectively mitigate various abiotic stresses such as manganese, aluminum and heavy metal toxicities, and salinity, drought, chilling and freezing stresses. However, mechanisms of Si-mediated alleviation of abiotic stresses remain poorly understood. The key mechanisms of Si-mediated alleviation of abiotic stresses in higher plants include: (1) stimulation of antioxidant systems in plants, (2) complexation or co-precipitation of toxic metal ions with Si, (3) immobilization of toxic metal ions in growth media, (4) uptake processes, and (5) compartmentation of metal ions within plants. Future research needs for Si-mediated alleviation of abiotic stresses are also discussed.

  17. Effects of Mechanical Stress and Plant Density on Mechanical Characteristics, Growth, and Lifetime Reproduction of Tobacco Plants

    NARCIS (Netherlands)

    Anten, N.P.R.; Casado-Garcia, R.; Nagashima, H.

    2005-01-01

    Plastic increases in stem elongation in dense vegetation are generally believed to be induced by canopy shading, but because plants protect each other from wind, shielding (reduced mechanical stress) could also play a role. To address this issue, tobacco Nicotiana tabacum plants were subjected to

  18. A methodology to incorporate life cycle analysis and the triple bottom line mechanism for sustainable management of industrial enterprises

    Science.gov (United States)

    Wang, Ling; Lin, Li

    2004-02-01

    Since 1970"s, the environmental protection movement has challenged industries to increase their investment in Environmentally Conscious Manufacturing (ECM) techniques and management tools. Social considerations for global citizens and their descendants also motivated the examination on the complex issues of sustainable development beyond the immediate economic impact. Consequently, industrial enterprises have started to understand sustainable development in considering the Triple Bottom Line (TBL): economic prosperity, environmental quality and social justice. For the management, however, a lack of systematic ECM methodologies hinders their effort in planning, evaluating, reporting and auditing of sustainability. To address this critical need, this research develops a framework of a sustainable management system by incorporating a Life Cycle Analysis (LCA) of industrial operations with the TBL mechanism. A TBL metric system with seven sets of indices for the TBL elements and their complex relations is identified for the comprehensive evaluation of a company"s sustainability performance. Utilities of the TBL indices are estimated to represent the views of various stakeholders, including the company, investors, employees and the society at large. Costs of these indices are also captured to reflect the company"s effort in meeting the utilities. An optimization model is formulated to maximize the economic, environmental and social benefits by the company"s effort in developing sustainable strategies. To promote environmental and social consciousness, the methodology can significantly facilitate management decisions by its capabilities of including "non-business" values and external costs that the company has not contemplated before.

  19. Potential mechanisms for a role of metabolic stress in hypertrophic adaptations to resistance training.

    Science.gov (United States)

    Schoenfeld, Brad J

    2013-03-01

    It is well established that regimented resistance training can promote increases in muscle hypertrophy. The prevailing body of research indicates that mechanical stress is the primary impetus for this adaptive response and studies show that mechanical stress alone can initiate anabolic signalling. Given the dominant role of mechanical stress in muscle growth, the question arises as to whether other factors may enhance the post-exercise hypertrophic response. Several researchers have proposed that exercise-induced metabolic stress may in fact confer such an anabolic effect and some have even suggested that metabolite accumulation may be more important than high force development in optimizing muscle growth. Metabolic stress pursuant to traditional resistance training manifests as a result of exercise that relies on anaerobic glycolysis for adenosine triphosphate production. This, in turn, causes the subsequent accumulation of metabolites, particularly lactate and H(+). Acute muscle hypoxia associated with such training methods may further heighten metabolic buildup. Therefore, the purpose of this paper will be to review the emerging body of research suggesting a role for exercise-induced metabolic stress in maximizing muscle development and present insights as to the potential mechanisms by which these hypertrophic adaptations may occur. These mechanisms include increased fibre recruitment, elevated systemic hormonal production, alterations in local myokines, heightened production of reactive oxygen species and cell swelling. Recommendations are provided for potential areas of future research on the subject.

  20. McKenzie treatment versus mulligan sustained natural apophyseal glides for chronic mechanical low back pain

    Science.gov (United States)

    Waqqar, Saira; Shakil-ur-Rehman, Syed; Ahmad, Shakeel

    2016-01-01

    Background and Objective: Chronic mechanical low back pain is common among different age groups and genders. Different manual therapy techniques combined with exercise therapy and electrotherapy modalities play an important role in its management. Our objective was to compare the effects of McKenzie extension exercisesprogram (EEP) versus Mulligan Sustained Natural Apophyseal Glides (SNAGs) for chronic mechanical low back pain (CMLBP). Methods: This randomized control trial (RCT) was conducted at Riphah Physical Rehabilitation Centre, Pakistan Railways General Hospital Rawalpindi, from 1st July to 31st December 2014. The inclusion criteria was patients of both gender and age range 30-70 years with minimum 4 weeks history of CMLBP. A total of 37 patients were screened out as per inclusion criteria and randomly placed into two groups. Twenty patients in group A were treated with Mulligan SNAGs and 17 patients in group B with McKenzie EEP for four weeks at two session per week and single session per day. Visual Analogue Scale (VAS), Oswestry Disability Scale (ODI) and lumber Range of Motion (ROM) were used as an assessment tools and were measured at baseline and at the completion 4 weeks intervention. The data was analyzed with SPSS to draw the statistical and clinical significance of both interventions. Results: At the completion of 4 weeks intervention the pre and post statistical analysis revealed that clinically the McKenzie EEP improved pain (mean 9.12 to 1.46) and disability (73.82 to 6.24) slightly more than Mulligan SNAGs (pain: from 8.85 to 2.55, disability 73.75 to 7.05), while the Mulligan SNAGs improved lumbar ROM more effectively than McKenzie EEP in all directions including flexion, extension, side bending and rotation. Statistically there was no significant difference between the effects of two interventions in managing pain and disability, and improving Lumber ROM. Conclusion: McKenzie EEP is clinically slightly more effective in the management of pain

  1. McKenzie treatment versus mulligan sustained natural apophyseal glides for chronic mechanical low back pain.

    Science.gov (United States)

    Waqqar, Saira; Shakil-Ur-Rehman, Syed; Ahmad, Shakeel

    2016-01-01

    Chronic mechanical low back pain is common among different age groups and genders. Different manual therapy techniques combined with exercise therapy and electrotherapy modalities play an important role in its management. Our objective was to compare the effects of McKenzie extension exercisesprogram (EEP) versus Mulligan Sustained Natural Apophyseal Glides (SNAGs) for chronic mechanical low back pain (CMLBP). This randomized control trial (RCT) was conducted at Riphah Physical Rehabilitation Centre, Pakistan Railways General Hospital Rawalpindi, from 1(st) July to 31(st) December 2014. The inclusion criteria was patients of both gender and age range 30-70 years with minimum 4 weeks history of CMLBP. A total of 37 patients were screened out as per inclusion criteria and randomly placed into two groups. Twenty patients in group A were treated with Mulligan SNAGs and 17 patients in group B with McKenzie EEP for four weeks at two session per week and single session per day. Visual Analogue Scale (VAS), Oswestry Disability Scale (ODI) and lumber Range of Motion (ROM) were used as an assessment tools and were measured at baseline and at the completion 4 weeks intervention. The data was analyzed with SPSS to draw the statistical and clinical significance of both interventions. At the completion of 4 weeks intervention the pre and post statistical analysis revealed that clinically the McKenzie EEP improved pain (mean 9.12 to 1.46) and disability (73.82 to 6.24) slightly more than Mulligan SNAGs (pain: from 8.85 to 2.55, disability 73.75 to 7.05), while the Mulligan SNAGs improved lumbar ROM more effectively than McKenzie EEP in all directions including flexion, extension, side bending and rotation. Statistically there was no significant difference between the effects of two interventions in managing pain and disability, and improving Lumber ROM. McKenzie EEP is clinically slightly more effective in the management of pain and disability as compared with Mulligan SNAGs

  2. Understanding the fluid mechanics behind transverse wall shear stress.

    Science.gov (United States)

    Mohamied, Yumnah; Sherwin, Spencer J; Weinberg, Peter D

    2017-01-04

    The patchy distribution of atherosclerosis within arteries is widely attributed to local variation in haemodynamic wall shear stress (WSS). A recently-introduced metric, the transverse wall shear stress (transWSS), which is the average over the cardiac cycle of WSS components perpendicular to the temporal mean WSS vector, correlates particularly well with the pattern of lesions around aortic branch ostia. Here we use numerical methods to investigate the nature of the arterial flows captured by transWSS and the sensitivity of transWSS to inflow waveform and aortic geometry. TransWSS developed chiefly in the acceleration, peak systolic and deceleration phases of the cardiac cycle; the reverse flow phase was too short, and WSS in diastole was too low, for these periods to have a significant influence. Most of the spatial variation in transWSS arose from variation in the angle by which instantaneous WSS vectors deviated from the mean WSS vector rather than from variation in the magnitude of the vectors. The pattern of transWSS was insensitive to inflow waveform; only unphysiologically high Womersley numbers produced substantial changes. However, transWSS was sensitive to changes in geometry. The curvature of the arch and proximal descending aorta were responsible for the principal features, the non-planar nature of the aorta produced asymmetries in the location and position of streaks of high transWSS, and taper determined the persistence of the streaks down the aorta. These results reflect the importance of the fluctuating strength of Dean vortices in generating transWSS. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Limits on crustal differential stress in southern California from topography and earthquake focal mechanisms

    Science.gov (United States)

    Luttrell, Karen; Smith-Konter, Bridget

    2017-10-01

    The in situ crustal stress field fundamentally governs, and is affected by, the active tectonic processes of plate boundary regions, yet questions remain about the characteristics of this field and the implications for active faults in the upper crust. We estimate the magnitude of differential stress at seismogenic depth in southern California by balancing in situ orientation indicated by earthquake focal mechanisms against the stress imposed by topography, which tends to resist the motion of strike-slip faults. Our results indicate that most regions require differential stress of at least 20 MPa at seismogenic depth. In the areas of most rugged topography along the San Andreas Fault System, differential stress at seismogenic depth must exceed 62 MPa consistent with differential stress estimates from complimentary methods. This furthermore suggests pore pressure must be less than lithostatic and that coefficient of friction cannot be very low (i.e. coefficient of static friction >0.3).

  4. Sustainable water use and management options in a water-stressed river basin in Kenya

    Science.gov (United States)

    Hirpa, Feyera; Dadson, Simon; Dyer, Ellen; Barbour, Emily; Charles, Katrina; Hope, Robert

    2017-04-01

    Sustainable water resource is critical for maintaining healthy ecosystems and supporting socio-economic sectors. Hydro-climatic change and variability, population growth as well as new infrastructure developments create water security risks. Therefore, evidence-based management decisions are necessary to improve water security and meet the future water demands of multiple competing sectors. In this work we perform water resource modelling in order to investigate the impact of increasing water demand (expanding agriculture, booming industry, growing population) on the sustainable water use in Turkwel river basin, located in arid north-western Kenya. We test different management options to determine those that meet the water demands of the concerned sectors whilst minimising environmental impact. We perform scenario analysis using Water Evaluation And Planning (WEAP) model to explore different ranges of climate conditions, population growth rates, irrigation scale, reservoir operations, and economic development. The results can be used as a scientific guideline for the policy makers who decide the alternative management options that ensure the sustainable water use in the basin. The work is part of the REACH - improving water security for the poor program (http://reachwater.org.uk/), aiming to support a pathway to sustainable growth and poverty reduction

  5. Hepatitis C Virus Infection Induces Autophagy as a Prosurvival Mechanism to Alleviate Hepatic ER-Stress Response

    Directory of Open Access Journals (Sweden)

    Srikanta Dash

    2016-05-01

    Full Text Available Hepatitis C virus (HCV infection frequently leads to chronic liver disease, liver cirrhosis and hepatocellular carcinoma (HCC. The molecular mechanisms by which HCV infection leads to chronic liver disease and HCC are not well understood. The infection cycle of HCV is initiated by the attachment and entry of virus particles into a hepatocyte. Replication of the HCV genome inside hepatocytes leads to accumulation of large amounts of viral proteins and RNA replication intermediates in the endoplasmic reticulum (ER, resulting in production of thousands of new virus particles. HCV-infected hepatocytes mount a substantial stress response. How the infected hepatocyte integrates the viral-induced stress response with chronic infection is unknown. The unfolded protein response (UPR, an ER-associated cellular transcriptional response, is activated in HCV infected hepatocytes. Over the past several years, research performed by a number of laboratories, including ours, has shown that HCV induced UPR robustly activates autophagy to sustain viral replication in the infected hepatocyte. Induction of the cellular autophagy response is required to improve survival of infected cells by inhibition of cellular apoptosis. The autophagy response also inhibits the cellular innate antiviral program that usually inhibits HCV replication. In this review, we discuss the physiological implications of the HCV-induced chronic ER-stress response in the liver disease progression.

  6. Mechanical Alterations Associated with Repeated Treadmill Sprinting under Heat Stress.

    Science.gov (United States)

    Girard, Olivier; Brocherie, Franck; Morin, Jean-Benoit; Racinais, Sébastien; Millet, Grégoire P; Périard, Julien D

    2017-01-01

    Examine the mechanical alterations associated with repeated treadmill sprinting performed in HOT (38°C) and CON (25°C) conditions. Eleven recreationally active males performed a 30-min warm-up followed by three sets of five 5-s sprints with 25-s recovery and 3-min between sets in each environment. Constant-velocity running for 1-min at 10 and 20 km.h-1 was also performed prior to and following sprinting. Mean skin (37.2±0.7 vs. 32.7±0.8°C; Pvertical stiffness were lower (-2.6±1.6% and -5.5±5.5%; both Pvertical (-2.6±5.5%; Pvertical stiffness (-12.9±2.3%; Pvertical stiffness during repeated sprinting; however without exacerbating mechanical alterations. The absence of changes in constant-velocity running patterns suggests a strong link between fatigue-induced velocity decrements during sprinting and mechanical alterations.

  7. Mechanical Stresses and Forces in Stereocilia Bundles of Inner and Outer Hair Cells

    Science.gov (United States)

    Mueller, R.; Maier, H.; Boehnke, F.; Arnold, W.

    2003-02-01

    The precise mechanism of mechanoelectrical transduction in stereocilia bundles is not known. It is very difficult to measure the extremely small stresses, which occur at the stereocilia bundles. Therefore we developed 3-D finite element models of stereocilia bundles (guinea pig) to obtain quantitative results. The stereocilia bundles of the outer hair cells show a characteristic W-form. Therefore, it is interesting to compare the mechanical behavior of the stereocilia bundle of an outer hair cell with that of an inner hair cell with its linear arrangement. Our analysis provides estimates of forces and stresses on the transducer channels of mammalian hair bundles, although the model does not include active mechanisms yet.

  8. Indirect Measurement of Energy Density of Soft PZT Ceramic Utilizing Mechanical Stress

    Science.gov (United States)

    Unruan, Muangjai; Unruan, Sujitra; Inkong, Yutthapong; Yimnirun, Rattikorn

    2017-11-01

    This paper reports on an indirect measurement of energy density of soft PZT ceramic utilizing mechanical stress. The method works analogous to the Olsen cycle and allows for a large amount of electro-mechanical energy conversion. A maximum energy density of 350 kJ/m3/cycle was found under 0-312 MPa and 1-20 kV/cm of applied mechanical stress and electric field, respectively. The obtained result is substantially higher than the results reported in previous studies of PZT materials utilizing a direct piezoelectric effect.

  9. Transcutaneous mechanical nerve stimulation using perineal vibration: a novel method for the treatment of female stress urinary incontinence

    DEFF Research Database (Denmark)

    Sønksen, Jens; Ohl, Dana A; Bonde, Birthe

    2007-01-01

    We defined basic guidelines for transcutaneous mechanical nerve stimulation in modifying pelvic floor responses in women and determined the efficacy of transcutaneous mechanical nerve stimulation in treating stress urinary incontinence.......We defined basic guidelines for transcutaneous mechanical nerve stimulation in modifying pelvic floor responses in women and determined the efficacy of transcutaneous mechanical nerve stimulation in treating stress urinary incontinence....

  10. A thermo-mechanical stress prediction model for contemporary planar sodium sulfur (NaS) cells

    Science.gov (United States)

    Jung, Keeyoung; Colker, Jeffrey P.; Cao, Yuzhe; Kim, Goun; Park, Yoon-Cheol; Kim, Chang-Soo

    2016-08-01

    We introduce a comprehensive finite-element analysis (FEA) computational model to accurately predict the thermo-mechanical stresses at heterogeneous joints and components of large-size sodium sulfur (NaS) cells during thermal cycling. Quantification of the thermo-mechanical stress is important because the accumulation of stress during cell assembly and/or operation is one of the critical issues in developing practical planar NaS cells. The computational model is developed based on relevant experimental assembly and operation conditions to predict the detailed stress field of a state-of-the-art planar NaS cell. Prior to the freeze-and-thaw thermal cycle simulation, residual stresses generated from the actual high temperature cell assembly procedures are calculated and implemented into the subsequent model. The calculation results show that large stresses are developed on the outer surface of the insulating header and the solid electrolyte, where component fracture is frequently observed in the experimental cell fabrication process. The impacts of the coefficients of thermal expansion (CTE) of glass materials and the thicknesses of cell container on the stress accumulation are also evaluated to improve the cell manufacturing procedure and to guide the material choices for enhanced thermo-mechanical stability of large-size NaS cells.

  11. Mechanisms of sustaining a radio-frequency atmospheric pressure planar discharge

    Science.gov (United States)

    Wang, Lei; Dinescu, Gheorghe; Deng, Xiaolong; Ionita, Eusebiu-Rosini; Leys, Christophe; Nikiforov, Anton Yu

    2017-07-01

    The time behavior of an atmospheric pressure planar discharge sustained in He gas was investigated experimentally and through two dimensional (2D) discharge simulation. The 30 mm long uniform α-mode discharge was observed at radio frequency (RF) input power below 35 W. The gas temperature of 375 ± 50 K in the discharge core was estimated by emission spectroscopy of OH(A-X) emission. A sheath region of about 100-150 μm width near both electrodes was observed during the whole RF cycle. However, there were differences in emission dynamics among various species detected in the discharge. OH(A) emission does not follow the RF voltage temporal variation. Strong He emission was always detected near the cathode, which was consistent with the 2D discharge simulation results. He-excited species production was found mainly due to the electron impact process. The simulation showed that both the electron and ion density vary from 1.88 × 1017 m-3 to 1.92 × 1017 m-3, and the electron temperature was about 1.85 eV in the plasma bulk. The ion temperature stayed close to the rotational temperature of OH radicals, and only increased near the sheath region to 0.65 eV. It was found that the mechanism of the sheath formation in atmospheric pressure discharge strongly correlates with the dynamics of the electron density and electron temperature variation in the gap, and the process is similar to low pressure RF capacitively coupled discharges. The high uniformity of the discharge and the upscale possibility to any desirable size are considered beneficial for industrial applications of the source, which is key for processes of thin coating deposition and polymer modification.

  12. Cortical and spinal mechanisms of task failure of sustained submaximal fatiguing contractions.

    Directory of Open Access Journals (Sweden)

    Petra S Williams

    Full Text Available In this and the subsequent companion paper, results are presented that collectively seek to delineate the contribution that supraspinal circuits have in determining the time to task failure (TTF of sustained submaximal contractions. The purpose of this study was to compare adjustments in supraspinal and spinal excitability taken concurrently throughout the performance of two different fatigue tasks with identical mechanical demands but different TTF (i.e., force-matching and position-matching tasks. On separate visits, ten healthy volunteers performed the force-matching or position-matching task at 15% of maximum strength with the elbow flexors to task failure. Single-pulse transcranial magnetic stimulation (TMS, paired-pulse TMS, paired cortico-cervicomedullary stimulation, and brachial plexus electrical stimulation were delivered in a 6-stimuli sequence at baseline and every 2-3 minutes throughout fatigue-task performance. Contrary to expectations, the force-matching task TTF was 42% shorter (17.5 ± 7.9 min than the position-matching task (26.9 ± 15.11 min; p0.05. Therefore, failure occurred after a similar mean decline in motorneuron excitability developed (p0.10 and an index of upstream excitation of the motor cortex remained constant (p>0.40. Together, these results suggest that as fatigue develops prior to task failure, the increase in corticospinal excitability observed in relationship to the decrease in spinal excitability results from a combination of decreasing intracortical inhibition with constant levels of intracortical facilitation and upstream excitability that together eventually fail to provide the input to the motor cortex necessary for descending drive to overcome the spinal cord resistance, thereby contributing to task failure.

  13. Cortical and Spinal Mechanisms of Task Failure of Sustained Submaximal Fatiguing Contractions

    Science.gov (United States)

    Williams, Petra S.; Hoffman, Richard L.; Clark, Brian C.

    2014-01-01

    In this and the subsequent companion paper, results are presented that collectively seek to delineate the contribution that supraspinal circuits have in determining the time to task failure (TTF) of sustained submaximal contractions. The purpose of this study was to compare adjustments in supraspinal and spinal excitability taken concurrently throughout the performance of two different fatigue tasks with identical mechanical demands but different TTF (i.e., force-matching and position-matching tasks). On separate visits, ten healthy volunteers performed the force-matching or position-matching task at 15% of maximum strength with the elbow flexors to task failure. Single-pulse transcranial magnetic stimulation (TMS), paired-pulse TMS, paired cortico-cervicomedullary stimulation, and brachial plexus electrical stimulation were delivered in a 6-stimuli sequence at baseline and every 2–3 minutes throughout fatigue-task performance. Contrary to expectations, the force-matching task TTF was 42% shorter (17.5±7.9 min) than the position-matching task (26.9±15.11 min; pmuscle fatigue (p = 0.59). There were no task-specific differences for the total amount or rate of change in the neurophysiologic outcome variables over time (p>0.05). Therefore, failure occurred after a similar mean decline in motorneuron excitability developed (p0.10) and an index of upstream excitation of the motor cortex remained constant (p>0.40). Together, these results suggest that as fatigue develops prior to task failure, the increase in corticospinal excitability observed in relationship to the decrease in spinal excitability results from a combination of decreasing intracortical inhibition with constant levels of intracortical facilitation and upstream excitability that together eventually fail to provide the input to the motor cortex necessary for descending drive to overcome the spinal cord resistance, thereby contributing to task failure. PMID:24667484

  14. Sustainable mechanical biological treatment of solid waste in urbanized areas with low recycling rates.

    Science.gov (United States)

    Trulli, Ettore; Ferronato, Navarro; Torretta, Vincenzo; Piscitelli, Massimiliano; Masi, Salvatore; Mancini, Ignazio

    2018-01-01

    Landfill is still the main technological facility used to treat and dispose municipal solid waste (MSW) worldwide. In developing countries, final dumping is applied without environmental monitoring and soil protection since solid waste is mostly sent to open dump sites while, in Europe, landfilling is considered as the last option since reverse logistic approaches or energy recovery are generally encouraged. However, many regions within the European Union continue to dispose of MSW to landfill, since modern facilities have not been introduced owing to unreliable regulations or financial sustainability. In this paper, final disposal activities and pre-treatment operations in an area in southern Italy are discussed, where final disposal is still the main option for treating MSW and the recycling rate is still low. Mechanical biological treatment (MBT) facilities are examined in order to evaluate the organic stabilization practices applied for MSW and the efficiencies in refuse derived fuel production, organic waste stabilization and mass reduction. Implementing MBT before landfilling the environmental impact and waste mass are reduced, up to 30%, since organic fractions are stabilized resulting an oxygen uptake rate less than 1600 mgO2 h-1 kg-1VS, and inorganic materials are exploited. Based on experimental data, this work examines MBT application in contexts where recycling and recovery activities have not been fully developed. The evidence of this study led to state that the introduction of MBT facilities is recommended for developing regions with high putrescible waste production in order to decrease environmental pollution and enhance human healthy. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Neural mechanisms of impaired fear inhibition in posttraumatic stress disorder

    Directory of Open Access Journals (Sweden)

    Tanja eJovanovic

    2011-07-01

    Full Text Available Posttraumatic stress disorder (PTSD can develop in some individuals who are exposed to an event that causes extreme fear, horror, or helplessness (APA, 1994. PTSD is a complex and heterogeneous disorder, which is often co-morbid with depression, substance abuse, and anxiety disorders such as panic or social phobia. Given this complexity, progress in the field can be greatly enhanced by focusing on phenotypes that are more proximal to the neurobiology of the disorder. Such neurobiological intermediate phenotypes can provide investigative tools to increase our understanding of the roots of the disorder and develop better prevention or intervention programs. In the present paper, we argue that the inhibition of fear responses is an intermediate phenotype that is related to both the neurocircuitry associated with the disorder, and is linked to its clinical symptoms. An advantage of focusing on fear inhibition is that the neurobiology of fear has been well investigated in animal models providing the necessary groundwork in understanding alterations. Furthermore, because many paradigms can be tested across species, fear inhibition is an ideal translational tool. Here we review both the behavioral tests and measures of fear inhibition and the related neurocircuitry in neuroimaging studies with both healthy and clinical samples.

  16. Convergent Neuronal Plasticity and Metaplasticity Mechanisms of Stress, Nicotine, and Alcohol.

    Science.gov (United States)

    Ostroumov, Alexey; Dani, John A

    2018-01-06

    Stress and tobacco smoking are risk factors for alcoholism, but the underlying neural mechanisms are not well understood. Although stress, nicotine, and alcohol have broad, individual effects in the brain, some of their actions converge onto the same mechanisms and circuits. Stress and nicotine augment alcohol-related behaviors, in part via modulation of alcohol-evoked neuronal plasticity and metaplasticity mechanisms. Stress modulates alcohol-evoked plasticity via the release of signaling molecules that influence synaptic transmission. Nicotine also activates some of the same signaling molecules, cells, and circuits, producing a convergence of both stress and nicotine onto common plasticity mechanisms that influence alcohol self-administration. We describe several forms of alcohol-induced plasticity, including classic Hebbian plasticity at glutamatergic synapses, and we highlight less appreciated forms, such as non-Hebbian and GABAergic synaptic plasticity. Risk factors such as stress and nicotine initiate lasting neural changes that modify subsequent alcohol-induced synaptic plasticity and increase the vulnerability to alcohol addiction.

  17. Exploring canopy structure and function as a potential mechanism of sustain carbon sequestration in aging forests

    Science.gov (United States)

    Fotis, A. T.; Curtis, P.; Ricart, R.

    2013-12-01

    The notion that old-growth forests reach carbon neutrality has recently been challenged, but the mechanisms responsible for continued productivity have remained elusive. Increases in canopy structural complexity, defined by high horizontal and vertical variability in leaf distribution (rugosity), has been proposed as a mechanism for sustained high rates of above ground net primary production (ANPPw) in forests up to ~170 years by enhancing light use efficiency (LUE) and nitrogen use efficiency (NUE). However, a detailed understanding of how rugosity affects resource distribution within and among trees leading to greater LUE and NUE is not known. We propose that leaves in high rugosity plots receive greater photosynthetic photon flux density (PPFD) than leaves in low rugosity plots, causing shifts from shade- to sun- adapted leaves into deeper portions of the canopy, which is thought to increase the photosynthetic capacity of individuals and lead to higher carbon assimilation in forests. The goal of this research was to: 1) quantify different canopy structural characteristics using a portable canopy LiDAR (PCL) and; 2) assess how these structural characteristics affect resource distribution and subsequent changes in leaf morphological, physiological and biochemical traits in three broadleaf species (e.g., Acer rubrum, Quercus rubra and Fagus grandifolia) and one conifer species (e.g., Pinus strobus) at different levels in the canopy in plots with similar leaf are index (LAI) but highly contrasting rugosity levels. We found that gap fraction had a strong positive correlation with rugosity. High rugosity plots had a bimodal distribution of LAI that was concentrated at the top and bottom of the canopy with an open midstory (between 10-50% of total canopy height) whereas low rugosity plots had a more even distribution of leaves. Leaf mass per area (LMA) of all broadleaved species had a strong positive correlation with cumulative gap fraction (P. strobus had a relatively

  18. No sustained attention differences in a longitudinal randomized trial comparing mindfulness based stress reduction versus active control.

    Directory of Open Access Journals (Sweden)

    Donal G MacCoon

    Full Text Available Mindfulness Based Stress Reduction (MBSR is a secular form of meditation training. The vast majority of the extant literature investigating the health effects of mindfulness interventions relies on wait-list control comparisons. Previous studies have found that meditation training over several months is associated with improvements in cognitive control and attention.We used a visual continuous performance task (CPT to test the effects of eight weeks of mindfulness training on sustained attention by comparing MBSR to the Health Enhancement Program (HEP, a structurally equivalent, active control condition in a randomized, longitudinal design (ClinicalTrials.gov, NCT01301105 focusing on a non-clinical population typical of MBSR participants. Researchers were blind to group assignment. 63 community participants were randomized to either MBSR (n = 31 or HEP (n = 32. CPT analyses were conducted on 29 MBSR participants and 25 HEP participants. We predicted that MBSR would improve visual discrimination ability and sustained attention over time on the CPT compared to HEP, with more home practice associated with greater improvements. Our hypotheses were not confirmed but we did find some evidence for improved visual discrimination similar to effects in partial replication of other research. Our study had sufficient power to demonstrate that intervention groups do not differ in their improvement over time in sustained attention performance. One of our primary predictions concerning the effects of intervention on attentional fatigue was significant but not interpretable.Attentional sensitivity is not affected by mindfulness practice as taught in MBSR, but it is unclear whether mindfulness might positively affect another aspect of attention, vigilance. These results also highlight the relevant procedural modifications required by future research to correctly investigate the role of sustained attention in similar samples.ClinicalTrials.gov, NCT

  19. Mindfulness-Based Stress Reduction in Post-treatment Breast Cancer Patients: Immediate and Sustained Effects Across Multiple Symptom Clusters.

    Science.gov (United States)

    Reich, Richard R; Lengacher, Cecile A; Alinat, Carissa B; Kip, Kevin E; Paterson, Carly; Ramesar, Sophia; Han, Heather S; Ismail-Khan, Roohi; Johnson-Mallard, Versie; Moscoso, Manolete; Budhrani-Shani, Pinky; Shivers, Steve; Cox, Charles E; Goodman, Matthew; Park, Jong

    2017-01-01

    Breast cancer survivors (BCS) face adverse physical and psychological symptoms, often co-occurring. Biologic and psychological factors may link symptoms within clusters, distinguishable by prevalence and/or severity. Few studies have examined the effects of behavioral interventions or treatment of symptom clusters. The aim of this study was to identify symptom clusters among post-treatment BCS and determine symptom cluster improvement following the Mindfulness-Based Stress Reduction for Breast Cancer (MBSR(BC)) program. Three hundred twenty-two Stage 0-III post-treatment BCS were randomly assigned to either a six-week MBSR(BC) program or usual care. Psychological (depression, anxiety, stress, and fear of recurrence), physical (fatigue, pain, sleep, and drowsiness), and cognitive symptoms and quality of life were assessed at baseline, six, and 12 weeks, along with demographic and clinical history data at baseline. A three-step analytic process included the error-accounting models of factor analysis and structural equation modeling. Four symptom clusters emerged at baseline: pain, psychological, fatigue, and cognitive. From baseline to six weeks, the model demonstrated evidence of MBSR(BC) effectiveness in both the psychological (anxiety, depression, perceived stress and QOL, emotional well-being) (P = 0.007) and fatigue (fatigue, sleep, and drowsiness) (P < 0.001) clusters. Results between six and 12 weeks showed sustained effects, but further improvement was not observed. Our results provide clinical effectiveness evidence that MBSR(BC) works to improve symptom clusters, particularly for psychological and fatigue symptom clusters, with the greatest improvement occurring during the six-week program with sustained effects for several weeks after MBSR(BC) training. Name and URL of Registry: ClinicalTrials.gov. Registration number: NCT01177124. Copyright © 2016. Published by Elsevier Inc.

  20. Mapping of Mechanical Strains and Stresses around Quiescent Engineered Three-Dimensional Epithelial Tissues

    Science.gov (United States)

    Gjorevski, Nikolce; Nelson, Celeste M.

    2012-01-01

    Understanding how physical signals guide biological processes requires qualitative and quantitative knowledge of the mechanical forces generated and sensed by cells in a physiologically realistic three-dimensional (3D) context. Here, we used computational modeling and engineered epithelial tissues of precise geometry to define the experimental parameters that are required to measure directly the mechanical stress profile of 3D tissues embedded within native type I collagen. We found that to calculate the stresses accurately in these settings, we had to account for mechanical heterogeneities within the matrix, which we visualized and quantified using confocal reflectance and atomic force microscopy. Using this technique, we were able to obtain traction forces at the epithelium-matrix interface, and to resolve and quantify patterns of mechanical stress throughout the surrounding matrix. We discovered that whereas single cells generate tension by contracting and pulling on the matrix, the contraction of multicellular tissues can also push against the matrix, causing emergent compression. Furthermore, tissue geometry defines the spatial distribution of mechanical stress across the epithelium, which communicates mechanically over distances spanning hundreds of micrometers. Spatially resolved mechanical maps can provide insight into the types and magnitudes of physical parameters that are sensed and interpreted by multicellular tissues during normal and pathological processes. PMID:22828342

  1. The level of stress and coping mechanism adopted by I Year B.Sc. nursing students

    Directory of Open Access Journals (Sweden)

    C Viji Prasad

    2013-01-01

    Full Text Available Background: Stress is a fact of life that every human deals with on a daily basis. In the transitional nature of student life in professional courses like nursing, initial period of course is stressful and it adversely affects the emotional, physical, social, and academic functions. Even though the perception and response to stress and way of coping differs individually, it may produce questionable behavioral patterns in student nurses during the course of their study like feeling of loneliness, nervousness, sleeplessness, and worrying. Thus, the student nurse faces a lot of challenges and problems at the time of I Year. Objectives: The present study aimed to determine the level of stress and coping mechanisms adopted by I Year B.Sc. nursing students. Materials and Methods: A total of 60 I Year B.Sc. nursing students were selected by using non-probability convenient sampling technique. The tools used for data collection were perceived stress scale, structured coping scale, and socio- demographic proforma. Results: The studies revealed that majority of students (95.1% were in the age group of 17-19 years. The results showed that only one student (1.7% has severe stress, 46.7% has moderate stress, and remaining 51.6% has mild stress, and majority of the students (100 had average coping. There was no significant correlation (-1.167 between stress and coping mechanism of I Year B.Sc. nursing students. Conclusion: Majority of students had mild stress and average coping. The nurse administrator should plan and organize educational program for nursing students, in order to prepare them to cope up with any stressful situations. Hence, the researcher emphasizes the need for more research to improve the knowledge and by applying the research finding for future.

  2. [Stress fractures].

    Science.gov (United States)

    Uhl, M

    2016-07-01

    Bone stress injuries are due to repetitive mechanical overuse of the skeleton and occur as a result of microscopic lesions sustained when bone is subjected to repeated submaximal stress. Over time accumulation of such injuries can lead to bone failure and fractures. Stress-related bone injuries are relatively common among otherwise healthy persons who have recently started new or intensified forms of physical training activities. Stress injuries lead to typical findings on radiography, bone scintigraphy, computed tomography (CT) and magnetic resonance imaging (MRI) and need to be discriminated from other conditions, in particular infections and neoplasms. Stress fractures must be differentiated from insufficiency fractures that occur in bones with reduced mechanical resistance or disturbed structure.

  3. Molecular mechanism of the priming by jasmonic acid of specific dehydration stress response genes in Arabidopsis.

    Science.gov (United States)

    Liu, Ning; Avramova, Zoya

    2016-01-01

    Plant genes that provide a different response to a similar dehydration stress illustrate the concept of transcriptional 'dehydration stress memory'. Pre-exposing a plant to a biotic stress or a stress-signaling hormone may increase transcription from response genes in a future stress, a phenomenon known as 'gene priming'. Although known that primed transcription is preceded by accumulation of H3K4me3 marks at primed genes, what mechanism provides for their appearance before the transcription was unclear. How augmented transcription is achieved, whether/how the two memory phenomena are connected at the transcriptional level, and whether similar molecular and/or epigenetic mechanisms regulate them are fundamental questions about the molecular mechanisms regulating gene expression. Although the stress hormone jasmonic acid (JA) was unable to induce transcription of tested dehydration stress response genes, it strongly potentiated transcription from specific ABA-dependent 'memory' genes. We elucidate the molecular mechanism causing their priming, demonstrate that stalled RNA polymerase II and H3K4me3 accumulate as epigenetic marks at the JA-primed ABA-dependent genes before actual transcription, and describe how these events occur mechanistically. The transcription factor MYC2 binds to the genes in response to both dehydration stress and to JA and determines the specificity of the priming. The MEDIATOR subunit MED25 links JA-priming with dehydration stress response pathways at the transcriptional level. Possible biological relevance of primed enhanced transcription from the specific memory genes is discussed. The biotic stress hormone JA potentiated transcription from a specific subset of ABA-response genes, revealing a novel aspect of the JA- and ABA-signaling pathways' interactions. H3K4me3 functions as an epigenetic mark at JA-primed dehydration stress response genes before transcription. We emphasize that histone and epigenetic marks are not synonymous and argue

  4. Mechanical Alterations Associated with Repeated Treadmill Sprinting under Heat Stress.

    Directory of Open Access Journals (Sweden)

    Olivier Girard

    Full Text Available Examine the mechanical alterations associated with repeated treadmill sprinting performed in HOT (38°C and CON (25°C conditions.Eleven recreationally active males performed a 30-min warm-up followed by three sets of five 5-s sprints with 25-s recovery and 3-min between sets in each environment. Constant-velocity running for 1-min at 10 and 20 km.h-1 was also performed prior to and following sprinting.Mean skin (37.2±0.7 vs. 32.7±0.8°C; P<0.001 and core (38.9±0.2 vs. 38.8±0.3°C; P<0.05 temperatures, together with thermal comfort (P<0.001 were higher following repeated sprinting in HOT vs. CON. Step frequency and vertical stiffness were lower (-2.6±1.6% and -5.5±5.5%; both P<0.001 and contact time (+3.2±2.4%; P<0.01 higher in HOT for the mean of sets 1-3 compared to CON. Running distance per sprint decreased from set 1 to 3 (-7.0±6.4%; P<0.001, with a tendency for shorter distance covered in HOT vs. CON (-2.7±3.4%; P = 0.06. Mean vertical (-2.6±5.5%; P<0.01, horizontal (-9.1±4.4%; P<0.001 and resultant ground reaction forces (-3.0±2.8%; P<0.01 along with vertical stiffness (-12.9±2.3%; P<0.001 and leg stiffness (-8.4±2.7%; P<0.01 decreased from set 1 to 3, independently of conditions. Propulsive power decreased from set 1 to 3 (-16.9±2.4%; P<0.001, with lower propulsive power values in set 2 (-6.6%; P<0.05 in HOT vs. CON. No changes in constant-velocity running patterns occurred between conditions, or from pre-to-post repeated-sprint exercise.Thermal strain alters step frequency and vertical stiffness during repeated sprinting; however without exacerbating mechanical alterations. The absence of changes in constant-velocity running patterns suggests a strong link between fatigue-induced velocity decrements during sprinting and mechanical alterations.

  5. Influence of Rapid Freeze-Thaw Cycling on the Mechanical Properties of Sustainable Strain-Hardening Cement Composite (2SHCC

    Directory of Open Access Journals (Sweden)

    Seok-Joon Jang

    2014-02-01

    Full Text Available This paper provides experimental results to investigate the mechanical properties of sustainable strain-hardening cement composite (2SHCC for infrastructures after freeze-thaw actions. To improve the sustainability of SHCC materials in this study, high energy-consumptive components—silica sand, cement, and polyvinyl alcohol (PVA fibers—in the conventional SHCC materials are partially replaced with recycled materials such as recycled sand, fly ash, and polyethylene terephthalate (PET fibers, respectively. To investigate the mechanical properties of green SHCC that contains recycled materials, the cement, PVA fiber and silica sand were replaced with 10% fly ash, 25% PET fiber, and 10% recycled aggregate based on preliminary experimental results for the development of 2SHCC material, respectively. The dynamic modulus of elasticity and weight for 2SHCC material were measured at every 30 cycles of freeze-thaw. The effects of freeze-thaw cycles on the mechanical properties of sustainable SHCC are evaluated by conducting compressive tests, four-point flexural tests, direct tensile tests and prism splitting tests after 90, 180, and 300 cycles of rapid freeze-thaw. Freeze-thaw testing was conducted according to ASTM C 666 Procedure A. Test results show that after 300 cycles of freezing and thawing actions, the dynamic modulus of elasticity and mass loss of damaged 2SHCC were similar to those of virgin 2SHCC, while the freeze-thaw cycles influence mechanical properties of the 2SHCC material except for compressive behavior.

  6. Reproduction in shark-attacked sea turtles is supported by stress-reduction mechanisms.

    Science.gov (United States)

    Jessop, Tim; Sumner, Joanna; Lance, Val; Limpus, Col

    2004-02-07

    Vertebrates exhibit varied behavioural and physiological tactics to promote reproductive success. We examined mechanisms that could enable female loggerhead turtles to undertake nesting activities and maintain seasonal reproduction despite recent shark injuries of varying severity. We proposed that endocrinal mechanisms that regulate both a turtle's stress response and reproductive ability are modified to promote successful and continued reproduction. Irrespective of the degree of injury, females did not exhibit increased levels of the stress hormone corticosterone, nor decreased levels of the reproductive steroid testosterone; hormone responses consistent with stress. When exposed to a capture stressor, females with shark injury did not exhibit any greater corticosterone response than controls. In addition, breeding females showed a reduced corticosterone stress response compared to non-breeding females. Reduced endocrinal responses following shark injury, and during breeding in general may, in part, enable females to maintain behavioural and physiological commitment to reproduction.

  7. Oxidative stress-related mechanisms affecting response to aspirin in diabetes mellitus.

    Science.gov (United States)

    Santilli, Francesca; Lapenna, Domenico; La Barba, Sara; Davì, Giovanni

    2015-03-01

    Type 2 diabetes mellitus (T2DM) is a major cardiovascular risk factor. Persistent platelet activation plays a key role in atherothrombosis in T2DM. However, current antiplatelet treatments appear less effective in T2DM patients vs nondiabetics at similar risk. A large body of evidence supports the contention that oxidative stress, which characterizes DM, may be responsible, at least in part, for less-than-expected response to aspirin, with multiple mechanisms acting at several levels. This review discusses the pathophysiological mechanisms related to oxidative stress and contributing to suboptimal aspirin action or responsiveness. These include: (1) mechanisms counteracting the antiplatelet effect of aspirin, such as reduced platelet sensitivity to the antiaggregating effects of NO, due to high-glucose-mediated oxidative stress; (2) mechanisms interfering with COX acetylation especially at the platelet level, e.g., lipid hydroperoxide-dependent impaired acetylating effects of aspirin; (3) mechanisms favoring platelet priming (lipid hydroperoxides) or activation (F2-isoprostanes, acting as partial agonists of thromboxane receptor), or aldose-reductase pathway-mediated oxidative stress, leading to enhanced platelet thromboxane A2 generation or thromboxane receptor activation; (4) mechanisms favoring platelet recruitment, such as aspirin-induced platelet isoprostane formation; (5) modulation of megakaryocyte generation and thrombopoiesis by oxidative HO-1 inhibition; and (6) aspirin-iron interactions, eventually resulting in impaired pharmacological activity of aspirin, lipoperoxide burden, and enhanced generation of hydroxyl radicals capable of promoting protein kinase C activation and platelet aggregation. Acknowledgment of oxidative stress as a major contributor, not only of vascular complications, but also of suboptimal response to antiplatelet agents in T2DM, may open the way to designing and testing novel antithrombotic strategies, specifically targeting

  8. THE MECHANISMS OF STRESS REACTIONS BY PERSONS OF DANGEROUS PROFESSIONS: METHODOLOGY OF PSYCHOPHYSIOLOGICAL RESEARCH

    Directory of Open Access Journals (Sweden)

    D. I. Tishakin

    2013-01-01

    Full Text Available In this article we are describe an experimental research dedicated to study of psychophysiological mechanisms of self-regulation by persons of dangerous professions. The study was conducted on a group of cadets of the military university. The methodology base includes the methods of psycho-diagnostics, psychophysiological testing, and specially designed protocols of stress-testing are modeled the stress situation. There short analysis of performed experiment is given by psychophysiological research position also conducts in article.

  9. Integrating Classical with Emerging Concepts for Better Understanding of Salinity Stress Tolerance Mechanisms in Rice

    Directory of Open Access Journals (Sweden)

    Navdeep Kaur

    2017-07-01

    Full Text Available Rice is an important cereal crop responsible for world's food security. The sensitivity of rice plants toward a range of abiotic stresses is a prime challenge for its overall growth and productivity. Among these, salinity is a major stress which results in a significant loss of global rice yield annually. For finding straightforward and strict future solutions in order to assure the food security to growing world population, understanding of the various mechanisms responsible for salt stress tolerance in rice is of paramount importance. In classical studies, identification of salt tolerant cultivars and the genetic markers linked to salt tolerance and breeding approaches have been given emphasis. It further affirmed on the identification of various pathways regulating the complex process of salt stress adaptation. However, only limited success has been achieved in these approaches as salt tolerance is a complex process and is governed by multiple factors. Hence, for better understanding of salt tolerance mechanisms, a comprehensive approach involving physiological, biochemical and molecular studies is much warranted. Modern experimental and genetic resources have provided a momentum in this direction and have provided molecular insights into different salt stress responsive pathways at the signaling and regulatory level. The integrative knowledge of classical and modern research of the understanding of salt stress adaptive pathways can help the researchers for designing effective strategies to fight against salt stress. Hence, the present review is focused on the understanding of the salt stress tolerance mechanisms in rice through the consolidative knowledge of classical and modern concepts. It further highlights the emerging new trends of salt stress adaptive pathways in rice.

  10. Thermo-mechanical stress analysis of cryopreservation in cryobags and the potential benefit of nanowarming.

    Science.gov (United States)

    Solanki, Prem K; Bischof, John C; Rabin, Yoed

    2017-06-01

    Cryopreservation by vitrification is the only promising solution for long-term organ preservation which can save tens of thousands of lives across the world every year. One of the challenges in cryopreservation of large-size tissues and organs is to prevent fracture formation due to the tendency of the material to contract with temperature. The current study focuses on a pillow-like shape of a cryobag, while exploring various strategies to reduce thermo-mechanical stress during the rewarming phase of the cryopreservation protocol, where maximum stresses are typically found. It is demonstrated in this study that while the level of stress may generally increase with the increasing amount of CPA filled in the cryobag, the ratio between width and length of the cryobag play a significant role. Counterintuitively, the overall maximum stress is not found when the bag is filled to its maximum capacity (when the filled cryobag resembles a sphere). Parametric investigation suggests that reducing the initial rewarming rate between the storage temperature and the glass transition temperature may dramatically decrease the thermo-mechanical stress. Adding a temperature hold during rewarming at the glass transition temperature may reduce the thermo-mechanical stress in some cases, but may have an adverse effect in other cases. Finally, it is demonstrated that careful incorporation of volumetric heating by means on nanoparticles in an alternating magnetic field, or nanowarming, can dramatically reduce the resulting thermo-mechanical stress. These observations display the potential benefit of a thermo-mechanical design of the cryopreservation protocols in order to prevent structural damage. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Subcellular and supracellular mechanical stress prescribes cytoskeleton behavior in Arabidopsis cotyledon pavement cells

    Science.gov (United States)

    Sampathkumar, Arun; Krupinski, Pawel; Wightman, Raymond; Milani, Pascale; Berquand, Alexandre; Boudaoud, Arezki; Hamant, Olivier; Jönsson, Henrik; Meyerowitz, Elliot M

    2014-01-01

    Although it is a central question in biology, how cell shape controls intracellular dynamics largely remains an open question. Here, we show that the shape of Arabidopsis pavement cells creates a stress pattern that controls microtubule orientation, which then guides cell wall reinforcement. Live-imaging, combined with modeling of cell mechanics, shows that microtubules align along the maximal tensile stress direction within the cells, and atomic force microscopy demonstrates that this leads to reinforcement of the cell wall parallel to the microtubules. This feedback loop is regulated: cell-shape derived stresses could be overridden by imposed tissue level stresses, showing how competition between subcellular and supracellular cues control microtubule behavior. Furthermore, at the microtubule level, we identified an amplification mechanism in which mechanical stress promotes the microtubule response to stress by increasing severing activity. These multiscale feedbacks likely contribute to the robustness of microtubule behavior in plant epidermis. DOI: http://dx.doi.org/10.7554/eLife.01967.001 PMID:24740969

  12. Mechanical-Stress Analytical Modeling for the Design of Coils in Power Applications

    Directory of Open Access Journals (Sweden)

    Bellan D.

    2014-12-01

    Full Text Available Modern electrical-power systems are often exploited for transmitting high-frequency carrier signals for communications purposes. Series-connected air-core coils represent the fundamental component allowing such applications by providing a proper filtering in the frequency domain. They must be designed, however, to withstand also the line short-circuit current. When a high-magnitude current flows through a coil, strong mechanical stresses are produced within the conductor, leading to possible damage of the coil. In this paper, an approximate analytical model is derived for the relationship between the maximum mechanical stress and the electrical/geometrical parameters of the coil. Such a model provides the guidelines for a fast and safe coil design, whereas numerical simulations are only needed for the design refinement. The presented approach can be extended to other applications such as, for example, the mechanical stress resulting from the inrush currents in the coils of power transformers.

  13. Mechanisms of Local Stress Sensing in Multifunctional Polymer Films Using Fluorescent Tetrapod Nanocrystals.

    Science.gov (United States)

    Raja, Shilpa N; Zherebetskyy, Danylo; Wu, Siva; Ercius, Peter; Powers, Alexander; Olson, Andrew C K; Du, Daniel X; Lin, Liwei; Govindjee, Sanjay; Wang, Lin-Wang; Xu, Ting; Alivisatos, A Paul; Ritchie, Robert O

    2016-08-10

    Nanoscale stress-sensing can be used across fields ranging from detection of incipient cracks in structural mechanics to monitoring forces in biological tissues. We demonstrate how tetrapod quantum dots (tQDs) embedded in block copolymers act as sensors of tensile/compressive stress. Remarkably, tQDs can detect their own composite dispersion and mechanical properties with a switch in optomechanical response when tQDs are in direct contact. Using experimental characterizations, atomistic simulations and finite-element analyses, we show that under tensile stress, densely packed tQDs exhibit a photoluminescence peak shifted to higher energies ("blue-shift") due to volumetric compressive stress in their core; loosely packed tQDs exhibit a peak shifted to lower energies ("red-shift") from tensile stress in the core. The stress shifts result from the tQD's unique branched morphology in which the CdS arms act as antennas that amplify the stress in the CdSe core. Our nanocomposites exhibit excellent cyclability and scalability with no degraded properties of the host polymer. Colloidal tQDs allow sensing in many materials to potentially enable autoresponsive, smart structural nanocomposites that self-predict impending fracture.

  14. Understanding brassinosteroid-regulated mechanisms to improve stress tolerance in plants: a critical review.

    Science.gov (United States)

    Nawaz, Fahim; Naeem, Muhammad; Zulfiqar, Bilal; Akram, Asim; Ashraf, Muhammad Yasin; Raheel, Muhammad; Shabbir, Rana Nauman; Hussain, Rai Altaf; Anwar, Irfan; Aurangzaib, Muhammad

    2017-07-01

    Brassinosteroids (BRs) are steroidal plant hormones involved in regulation of physiological and molecular processes to ameliorate various biotic and abiotic stresses. Exogenous application of BRs to improve stress tolerance in plants has recently become a high research priority. Several studies have revealed the involvement of these steroidal hormones in upregulation of stress-related defense genes and their cross talk with other metabolic pathways. This is likely to stimulate research on many unanswered questions regarding their role in enhancing the ability of plants to tolerate adverse environmental conditions. Thus, this review appraises new insights on mechanisms mediating BR-regulated changes in plants, focused mainly on their involvement in regulation of physiological and molecular mechanisms under stress conditions. Herein, examples of BR-stimulated modulation of antioxidant defense system and upregulation of transcription factors in plants exposed to various biotic (bacterial, viral, and fungal attack) and abiotic stresses (drought, salinity, heat, low temperature, and heavy metal stress) are discussed. Based on these insights, future research in the current direction can be helpful to increase our understanding of BR-mediated complex and interrelated processes under stress conditions.

  15. Environmental Sustainability of Agriculture Stressed by Changing Extremes of Drought and Excess Moisture: A Conceptual Review

    Directory of Open Access Journals (Sweden)

    Elaine Wheaton

    2017-06-01

    Full Text Available As the climate changes, the effects of agriculture on the environment may change. In the future, an increasing frequency of climate extremes, such as droughts, heat waves, and excess moisture, is expected. Past research on the interaction between environment and resources has focused on climate change effects on various sectors, including agricultural production (especially crop production, but research on the effects of climate change using agri-environmental indicators (AEI of environmental sustainability of agriculture is limited. The aim of this paper was to begin to address this knowledge gap by exploring the effects of future drought and excess moisture on environmental sustainability of agriculture. Methods included the use of a conceptual framework, literature reviews, and an examination of the climate sensitivities of the AEI models. The AEIs assessed were those for the themes of soil and water quality, and farmland management as developed by Agriculture and Agri-Food Canada. Additional indicators included one for desertification and another for water supply and demand. The study area was the agricultural region of the Canadian Prairie Provinces. We found that the performance of several indicators would likely decrease in a warming climate with more extremes. These indicators with declining performances included risks for soil erosion, soil salinization, desertification, water quality and quantity, and soil contamination. Preliminary trends of other indicators such as farmland management were not clear. AEIs are important tools for measuring climate impacts on the environmental sustainability of agriculture. They also indicate the success of adaptation measures and suggest areas of operational and policy development. Therefore, continued reporting and enhancement of these indicators is recommended.

  16. Trophic mechanisms for exercise-induced stress resilience: Potential role of interactions between BDNF and galanin

    Directory of Open Access Journals (Sweden)

    Philip V Holmes

    2014-07-01

    Full Text Available Current concepts of the neurobiology of stress-related disorders such as anxiety and depression emphasize disruptions in neural plasticity and neurotrophins. The potent trophic actions of exercise therefore represent not only an effective means for prevention and treatment of these disorders, they also afford the opportunity to employ exercise paradigms as a basic research tool to uncover the neurobiological mechanisms underlying these disorders. Novel approaches to studying stress-related disorders focus increasingly on trophic factor signaling in corticolimbic circuits that both mediate and regulate cognitive, behavioral, and physiological responses to deleterious stress. Recent evidence demonstrates that the neural plasticity supported by these trophic mechanisms is vital for establishing and maintaining resilience to stress. Therapeutic interventions that promote these mechanisms, be they pharmacological, behavioral, or environmental, may therefore prevent or reverse stress-related mental illness by enhancing resilience. The present paper will provide an overview of trophic mechanisms responsible for the enhancement of resilience by voluntary exercise with an emphasis on BDNF, galanin, and interactions between these two trophic factors.

  17. Stress, deformation, conservation, and rheology: a survey of key concepts in continuum mechanics

    Science.gov (United States)

    Major, J.J.

    2013-01-01

    This chapter provides a brief survey of key concepts in continuum mechanics. It focuses on the fundamental physical concepts that underlie derivations of the mathematical formulations of stress, strain, hydraulic head, pore-fluid pressure, and conservation equations. It then shows how stresses are linked to strain and rates of distortion through some special cases of idealized material behaviors. The goal is to equip the reader with a physical understanding of key mathematical formulations that anchor continuum mechanics in order to better understand theoretical studies published in geomorphology.

  18. The pathology of cellular anti-stress mechanisms: a new frontier.

    Science.gov (United States)

    Macario, Alberto J L; Conway de Macario, Everly

    2004-12-01

    Exposure to stressors is an omnipresent variable for all living organisms, which have evolved anti-stress mechanisms to deal with the consequences of stress. The chaperoning systems are among these mechanisms, and their central components are the molecular chaperones that play important roles in protein biogenesis. Recent data suggest that failure of the chaperoning systems due to defective chaperones, for example, leads to pathology. Consequently, medical researchers and practitioners must now also consider the chaperoning systems, both as potentially major players in pathogenesis and as diagnostic-prognostic indicators.

  19. The influence of strengthening mechanisms on stress relaxation in thin aluminum metallization

    Energy Technology Data Exchange (ETDEWEB)

    Gorrell, J.; Holloway, P. [Univ. of Florida, Gainesville, FL (United States). Dept. of Materials Science and Engineering; Jerman, H. [EG and G IC Sensors, Milpitas, CA (United States)

    1997-05-01

    The objective of this research is to identify ways of strengthening aluminum thin films for use in bimetallic actuators. With the development of microelectromechanical systems there is a need for stronger aluminium thin films that resist stress relaxation. A number of strengthening mechanisms are used extensively for bulk aluminum alloys, but very few have been used to improve the performance of thin films. Pure aluminum, standard microelectronics metallization (Al-.04Cu-.017Si), alloy T201 (Al-.046Cu-.006Ag-.004Mn-.003Mg-.003Ti), and alloy 2090 (Al-.026Cu-.021Li-.001Zr) were electron beam evaporated or sputter deposited onto (100) silicon substrates. Stress versus temperature and stress relaxation were measured in the films. Pure aluminum and AlSiCu alloy films exhibited plastic deformation at low stresses and low temperatures. The T201 and 2090 films exhibited residual elastic stresses at room temperature of 350 MPa and 500 MPa, and did not plastically deform until 240 C at 100 MPa stress, or 270 C at 200 MPa stress, respectively. The T201 film also showed a low stress relaxation rate. The authors speculate that solid solution strengthening caused the increase in strength of the T201 film, and that age hardening caused the increase in strength of the 2090 film.

  20. [Effects of stress on hippocampal Glu-NMDAR pathway in rats and mechanism of zinc protection].

    Science.gov (United States)

    Geng, Zhan-hui; Cheng, Yi-yong; Ma, Xiu-ling; Li, Shu-tian; Wang, Yong-hui; Shi, Hui-ling

    2003-05-01

    To observe the effects of stress on Glu uptake and NMDAR of hippocampus synaptosome in rats with different zinc status. Stress model was established by photoelectric stimulus. The behaviors of rats were tested in open-field case. 3H-L-Glu was taken as radioligand to detect the NMDAR binding. Glu uptake was determined with radioimmunoassay. Compared with CT rats, ZD rats performed less movement in open-field test, both Bmax of NMDAR and 3H-L-Glu uptake of hippocampus in these rats were significantly decreased. Compared with corresponding non-stressed groups, the stressed groups appeared longer latency and less movement in open-field test. Increased Bmax of NMDAR and decreased 3H-L-Glu uptake were observed in all stressed rats, but only in SZD rats these indices showed statistical difference. Abnormal behaviors of rats induced by photoelectric stress were observed in open-field test, which was more serious in zinc deficiency rats. It is supposed that the Glu-NMDAR pathway is involved in the process of stress reaction. As it shows in our experiment, the changes of Bmax of NMDAR and 3H-L-Glu uptake of hippocampus synaptosome seems to be a part of the mechanisms of stress action.

  1. Creep and stress rupture of oxide dispersion strengthened mechanically alloyed Inconel alloy MA 754

    Science.gov (United States)

    Howson, T. E.; Tien, J. K.; Stulga, J. E.

    1980-01-01

    The creep and stress rupture behavior of the mechanically alloyed oxide dispersion strengthened nickel-base alloy MA 754 was studied at 760, 982 and 1093 C. Tensile specimens with a fine, highly elongated grain structure, oriented parallel and perpendicular to the longitudinal grain direction were tested at various stresses in air under constant load. It was found that the apparent stress dependence was large, with power law exponents ranging from 19 to 33 over the temperature range studied. The creep activation energy, after correction for the temperature dependence of the elastic modulus, was close to but slightly larger than the activation energy for self diffusion. Rupture was intergranular and the rupture ductility as measured by percentage elongation was generally low, with values ranging from 0.5 to 16 pct. The creep properties are rationalized by describing the creep rates in terms of an effective stress which is the applied stress minus a resisting stress consistent with the alloy microstructure. Values of the resisting stress obtained through a curve fitting procedure are found to be close to the values of the particle by-pass stress for this oxide dispersion strengthened alloy, as calculated from the measured oxide particle distribution.

  2. Mechanisms of Residual Stress Generation in Mechanical Surface Treatment: the Role of Cyclic Plasticity and Texture

    Science.gov (United States)

    2015-08-24

    silicon substrates", Surface and Coatings Technology , vol. 176, no. 1, pp. 124-130. Clauer, A. 1996, Laser shock peening for fatigue resistance...Li Base Products for Aerospace and Space Applications", Metallurgical and Materials Transactions A, vol. 43, no. 9, pp. 3325-3337. Rodopoulos, C.A...34, Optics and Laser Technology , vol. 45, no. 1, pp. 389-394. Sticchi, M., Schnubel, D., Kashaev, N. & Huber, N. 2014, " Review of Residual Stress

  3. Increased endoplasmic reticulum stress in mouse osteocytes with aging alters Cox-2 response to mechanical stimuli.

    Science.gov (United States)

    Chalil, Sreeda; Jaspers, Richard T; Manders, Ralph J; Klein-Nulend, Jenneke; Bakker, Astrid D; Deldicque, Louise

    2015-02-01

    Aging reduces bone mass as well as the anabolic response of bone to mechanical stimuli, resulting in osteopenia. Endoplasmic reticulum (ER) stress impairs the response of myogenic cells to anabolic stimuli, and is involved in sarcopenia, but whether ER stress also contributes to osteopenia is unknown. Therefore, we tested whether ER stress exists in bones of aged mice, and whether this impairs the osteocyte response to mechanical stimulation. Primary osteocytes were obtained from long bones of adult (8 months) and old (24-26 months) mice, treated with or without the pharmacological ER stress inducer tunicamycin, and either or not subjected to mechanical loading by pulsating fluid flow (PFF). The osteocyte response to PFF was assessed by measuring cyclooxygenase-2 (Cox-2) mRNA levels and nitric oxide (NO) production. mRNA levels of ER stress markers were higher in old versus adult osteocytes (+40% for activating transcription factor-4, +120% for C/EBP homologous protein, and +120% for spliced X-box binding protein-1, p Cox-2 response to PFF was fourfold decreased in cells from old bones (p Cox-2 expression by threefold in cells from adult bones (p < 0.01). PFF increased NO production by 50% at 60 min in osteocytes from old versus adult bones (p < 0.01). In conclusion, our data indicate that the expression of several ER stress markers was higher in osteocytes from bones of old compared to adult mice. Since ER stress altered the response of osteocytes to mechanical loading, it could be a novel factor contributing to osteopenia.

  4. Mechanical stress impairs mitosis progression in multi-cellular tumor spheroids.

    Directory of Open Access Journals (Sweden)

    Annaïck Desmaison

    Full Text Available Growing solid tumors are subjected to mechanical stress that influences their growth rate and development. However, little is known about its effects on tumor cell biology. To explore this issue, we investigated the impact of mechanical confinement on cell proliferation in MultiCellular Tumor Spheroids (MCTS, a 3D culture model that recapitulates the microenvironment, proliferative gradient, and cell-cell interactions of a tumor. Dedicated polydimethylsiloxane (PDMS microdevices were designed to spatially restrict MCTS growth. In this confined environment, spheroids are likely to experience mechanical stress as indicated by their modified cell morphology and density and by their relaxation upon removal from the microdevice. We show that the proliferation gradient within mechanically confined spheroids is different in comparison to MCTS grown in suspension. Furthermore, we demonstrate that a population of cells within the body of mechanically confined MCTS is arrested at mitosis. Cell morphology analysis reveals that this mitotic arrest is not caused by impaired cell rounding, but rather that confinement negatively affects bipolar spindle assembly. All together these results suggest that mechanical stress induced by progressive confinement of growing spheroids could impair mitotic progression. This study paves the way to future research to better understand the tumor cell response to mechanical cues similar to those encountered during in vivo tumor development.

  5. Confronting Future Risks of Global Water Stress and Sustainability: Avoided Changes Versus Adaptive Actions

    Science.gov (United States)

    Schlosser, C. A.; Strzepek, K. M.; Gao, X.; Fant, C.; Paltsev, S.; Monier, E.; Sokolov, A. P.; Winchester, N.; Chen, H.; Kicklighter, D. W.; Ejaz, Q.

    2016-12-01

    We examine the fate of global water resources under a range of self-consistent socio-economic projections using the MIT Integrated Global System Model (IGSM) under a range of plausible mitigation and adaptation scenarios of development to the water-energy-land systems and against an assessment of the results from the UN COP-21 meeting. We assess the trends of an index of managed water stress as well as unmet water demands as simulated by the Water Resource System within the IGSM framework (IGSM-WRS). The WRS is forced by the simulations of the global climate response, variations in regional climate pattern changes, as well as the socio-economic drivers from the IGSM scenarios. We focus on the changes in water-stress metrics in the coming decades and going into the latter half of this century brought about by our projected climate and socio-economic changes, as well as the total (additional) populations affected by increased stress. We highlight selected basins to demonstrate sensitivities and interplay between supply and demand, the uncertainties in global climate sensitivity as well as regional climate change, and their implications to assessing and reducing water risks and the populations affected by water scarcity. We also evaluate the impact of explicitly representing irrigated land and water scarcity in an economy-wide model on food prices, bioenergy production and deforestation both with and without a global carbon policy. We highlight the importance of adaptive measures that will be required, worldwide, to meet surface-water shortfalls even under more aggressive and certainly under intermediate climate mitigation pathways - and further analyses is presented in this context quantifying risks averted and their associated costs. In addition, we also demonstrate that the explicit representation of irrigated land within this intergrated modeling frameowork has a small impact on food, bioenergy and deforestation outcomes within the scenarios considered

  6. Group cognitive behaviour therapy for military service-related post-traumatic stress disorder: effectiveness, sustainability and repeatability.

    Science.gov (United States)

    Khoo, Andrew; Dent, Michael T; Oei, Tian P S

    2011-08-01

    The aim of this study was to assess 12 month outcomes of Australian combat veterans with post-traumatic stress disorder (PTSD) who participated in a 6 week group-based CBT programme at the Toowong Private Hospital. The study population included 496 consecutive admissions to the programme between 1999 and 2008. Self-report measures of PTSD, depression, anxiety, anger, alcohol use, relationship satisfaction and quality of life parameters were collected at intake and 3, 6 and 12 months post intake. Statistically significant and sustained improvements were noted in 12 month outcome measures for PTSD, depression, anxiety, alcohol use, anger, and quality of life. PTSD symptom reduction occurred consistently each year for 9 years and exhibited an aggregated effect size of 0.68. This naturalistic research demonstrates that treatment administered under clinical conditions produces equivocal magnitudes of positive change in terms of PTSD symptoms when compared with existing efficacy data in individual and group treatments. Further, these symptomatic gains are sustainable and consistently reproducible. The benefits noted from group therapy were seen as independent of whether or not individual treatment was in place.

  7. Effects of Nitrogen Supply on Water Stress and Recovery Mechanisms in Kentucky Bluegrass Plants.

    Science.gov (United States)

    Saud, Shah; Fahad, Shah; Yajun, Chen; Ihsan, Muhammad Z; Hammad, Hafiz M; Nasim, Wajid; Amanullah; Arif, Muhammad; Alharby, Hesham

    2017-01-01

    Non-irrigated crops in temperate and irrigated crops in arid regions are exposed to an incessant series of drought stress and re-watering. Hence, quick and efficient recuperation from drought stress may be amongst the key determinants of plant drought adjustment. Efficient nitrogen (N) nutrition has the capability to assuage water stress in crops by sustaining metabolic activities even at reduced tissue water potential. This study was designed to understand the potential of proper nutrition management by studying the morphological and physiological attributes, and assimilation of nitrogen in Kentucky bluegrass under drought stress. In present study, one heterogeneous habitat and four treatments homogenous habitats each with four replications were examined during field trial. Drought stress resulted in a significant reduction in the nitrogen content of both mother and first ramets, maximum radius, above and below ground mass, number of ramets per plot, leaf water contents and water potential and increased the carbon content and the C:N ratio in both homogenous and heterogeneous plots compared to well-watered and nutritional conditions. Observation using electron microscopy showed that drought stress shrunk the vessel diameter, circumference and xylem area, but increased the sieve diameter, and phloem area in the leaf crosscutting structure of Kentucky bluegrass, first, second, and third ramet leaf. Thus, it can be concluded that water stress markedly reduced all the important traits of Kentucky bluegrass, however, proper nutritional management treatment resulted in the best compensatory performance under drought assuaging its adversity up to some extent and may be considered in formulating good feasible and cost-effective practices for the environmental circumstances related to those of this study.

  8. Effects of Nitrogen Supply on Water Stress and Recovery Mechanisms in Kentucky Bluegrass Plants

    Science.gov (United States)

    Saud, Shah; Fahad, Shah; Yajun, Chen; Ihsan, Muhammad Z.; Hammad, Hafiz M.; Nasim, Wajid; Amanullah; Arif, Muhammad; Alharby, Hesham

    2017-01-01

    Non-irrigated crops in temperate and irrigated crops in arid regions are exposed to an incessant series of drought stress and re-watering. Hence, quick and efficient recuperation from drought stress may be amongst the key determinants of plant drought adjustment. Efficient nitrogen (N) nutrition has the capability to assuage water stress in crops by sustaining metabolic activities even at reduced tissue water potential. This study was designed to understand the potential of proper nutrition management by studying the morphological and physiological attributes, and assimilation of nitrogen in Kentucky bluegrass under drought stress. In present study, one heterogeneous habitat and four treatments homogenous habitats each with four replications were examined during field trial. Drought stress resulted in a significant reduction in the nitrogen content of both mother and first ramets, maximum radius, above and below ground mass, number of ramets per plot, leaf water contents and water potential and increased the carbon content and the C:N ratio in both homogenous and heterogeneous plots compared to well-watered and nutritional conditions. Observation using electron microscopy showed that drought stress shrunk the vessel diameter, circumference and xylem area, but increased the sieve diameter, and phloem area in the leaf crosscutting structure of Kentucky bluegrass, first, second, and third ramet leaf. Thus, it can be concluded that water stress markedly reduced all the important traits of Kentucky bluegrass, however, proper nutritional management treatment resulted in the best compensatory performance under drought assuaging its adversity up to some extent and may be considered in formulating good feasible and cost-effective practices for the environmental circumstances related to those of this study. PMID:28642781

  9. Pulsatile Hyperglycaemia Induces Vascular Oxidative Stress and GLUT 1 Expression More Potently than Sustained Hyperglycaemia in Rats on High Fat Diet

    DEFF Research Database (Denmark)

    Rakipovski, Gunaj; Lykkesfeldt, Jens; Raun, Kirsten

    2016-01-01

    expression of glucose transporter 1 (GLUT1), gp-91(PHOX) and super oxide dismutase (SOD), while only the PLG group showed increased accumulation of oxidative stress and oxidised low density lipoprotein (oxLDL) in aorta. Conclusion Pulsatile hyperglycaemia induced relatively higher levels of oxidative stress...... systemically and in aorta in particular than overt sustained hyperglycaemia thus supporting the clinical observations that pulsatile hyperglycaemia is an independent risk factor for diabetes related macrovascular complications....

  10. The mechanics of delamination in fiber-reinforced composite materials. I - Stress singularities and solution structure

    Science.gov (United States)

    Wang, S. S.; Choi, I.

    1983-01-01

    The fundamental mechanics of delamination in fiber composite laminates is studied. Mathematical formulation of the problem is based on laminate anisotropic elasticity theory and interlaminar fracture mechanics concepts. Stress singularities and complete solution structures associated with general composite delaminations are determined. For a fully open delamination with traction-free surfaces, oscillatory stress singularities always appear, leading to physically inadmissible field solutions. A refined model is introduced by considering a partially closed delamination with crack surfaces in finite-length contact. Stress singularities associated with a partially closed delamination having frictional crack-surface contact are determined, and are found to be different from the inverse square-root one of the frictionless-contact case. In the case of a delamination with very small area of crack closure, a simplified model having a square-root stress singularity is employed by taking the limit of the partially closed delamination. The possible presence of logarithmic-type stress singularity is examined; no logarithmic singularity of any kind is found in the composite delamination problem. Numerical examples of dominant stress singularities are shown for delaminations having crack-tip closure with different frictional coefficients between general (1) and (2) graphite-epoxy composites. Previously announced in STAR as N84-13221

  11. Oxidative stress is required for mechanical ventilation-induced protease activation in the diaphragm

    Science.gov (United States)

    Smuder, Ashley J.; Wu, Min; Hudson, Matthew B.; Nelson, W. Bradley; Powers, Scott K.

    2010-01-01

    Prolonged mechanical ventilation (MV) results in diaphragmatic weakness due to fiber atrophy and contractile dysfunction. Recent work reveals that activation of the proteases calpain and caspase-3 is required for MV-induced diaphragmatic atrophy and contractile dysfunction. However, the mechanism(s) responsible for activation of these proteases remains unknown. To address this issue, we tested the hypothesis that oxidative stress is essential for the activation of calpain and caspase-3 in the diaphragm during MV. Cause-and-effect was established by prevention of MV-induced diaphragmatic oxidative stress using the antioxidant Trolox. Treatment of animals with Trolox prevented MV-induced protein oxidation and lipid peroxidation in the diaphragm. Importantly, the Trolox-mediated protection from MV-induced oxidative stress prevented the activation of calpain and caspase-3 in the diaphragm during MV. Furthermore, the avoidance of MV-induced oxidative stress not only averted the activation of these proteases but also rescued the diaphragm from MV-induced diaphragmatic myofiber atrophy and contractile dysfunction. Collectively, these findings support the prediction that oxidative stress is required for MV-induced activation of calpain and caspase-3 in the diaphragm and are consistent with the concept that antioxidant therapy can retard MV-induced diaphragmatic weakness. PMID:20203072

  12. Effects of the three-dimensional residual stresses on the mechanical properties of arterial walls.

    Science.gov (United States)

    Zheng, Xianbing; Ren, Jiusheng

    2016-03-21

    Effects of the three-dimensional residual stresses on the mechanical properties of arterial walls are analyzed in this paper, based on the model which considered the bending and stretching both in the circumferential and axial directions of the three distinct arterial layers. Moreover, different constitutive models are proposed to quantify the nonlinear mechanics of the three distinct layers and the important constituents, i.e. elastin, collagen fibers and smooth muscle cells (SMCs), are all taken into account. The stress distributions and pressure-radius curves of the arterial wall are given in details. Results demonstrate that the maximum values of the circumferential stress and the corresponding stress gradient in the media under the mean arterial pressure are reduced significantly as a consequence of the SMCs. The bending in the axial direction of the media and the opening angle of the intima have an obvious impact on the mechanical behaviors of arterial walls. This study may not only develop the understanding of effects of the three-dimensional residual stresses on the arterial wall response, but also can increase the accuracy of the analyses for patient-specific studies used for the treatments of arterial diseases. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Non-Contact Technique for Determining the Mechanical Stress in thin Films on Wafers by Profiler

    Science.gov (United States)

    Djuzhev, N. A.; Dedkova, A. A.; E Gusev, E.; Makhiboroda, M. A.; Glagolev, P. Y.

    2017-04-01

    This paper presents an algorithm for analysis of relief for the purpose of calculating mechanical stresses in a selected direction on the plate in the form of software package Matlab. The method allows for the measurement sample in the local area. It provides a visual representation of the data and allows to get stress distribution on wafer surface. Automated analysis process reduces the likelihood of errors researcher. Achieved time saving during processing results. In carrying out several measurements possible drawing card plate to predict yield crystals. According to this technique done in measurement of mechanical stresses of thermal silicon oxide film on a silicon substrate. Analysis of the results showed objectivity and reliability calculations. This method can be used for selecting the optimal parameters of the material deposition conditions. In software of device-technological simulation TCAD defined process time, temperature and oxidation of the operation of the sample environment for receiving the set value of the dielectric film thickness. Calculated thermal stresses are in the system silicon-silicon oxide. There is a good correlation between numerical simulations and analytical calculation. It is shown that the nature of occurrence of mechanical stress is not limited to the difference of thermal expansion coefficients of materials.

  14. The Best of Two Worlds. Article 6 mechanisms shall contribute to Sustainable Development Goals (SDGs)

    DEFF Research Database (Denmark)

    Olsen, Karen Holm; Soezer, Alexandra

    2016-01-01

    The Paris Agreement and the UN Sustainable Development Goals (SDGs) were two milestone achievements in 2015. The Intended Nationally Determined Contributions (INDCs) put forward by Parties before the Climate Conference in Paris will have to be fully embedded in the 2030 agenda to achieve truly...

  15. Stress, burnout and depression: A systematic review on DNA methylation mechanisms.

    Science.gov (United States)

    Bakusic, Jelena; Schaufeli, Wilmar; Claes, Stephan; Godderis, Lode

    2017-01-01

    Despite that burnout presents a serious burden for modern society, there are no diagnostic criteria. Additional difficulty is the differential diagnosis with depression. Consequently, there is a need to dispose of a burnout biomarker. Epigenetic studies suggest that DNA methylation is a possible mediator linking individual response to stress and psychopathology and could be considered as a potential biomarker of stress-related mental disorders. Thus, the aim of this review is to provide an overview of DNA methylation mechanisms in stress, burnout and depression. In addition to state-of-the-art overview, the goal of this review is to provide a scientific base for burnout biomarker research. We performed a systematic literature search and identified 25 pertinent articles. Among these, 15 focused on depression, 7 on chronic stress and only 3 on work stress/burnout. Three epigenome-wide studies were identified and the majority of studies used the candidate-gene approach, assessing 12 different genes. The glucocorticoid receptor gene (NR3C1) displayed different methylation patterns in chronic stress and depression. The serotonin transporter gene (SLC6A4) methylation was similarly affected in stress, depression and burnout. Work-related stress and depressive symptoms were associated with different methylation patterns of the brain derived neurotrophic factor gene (BDNF) in the same human sample. The tyrosine hydroxylase (TH) methylation was correlated with work stress in a single study. Additional, thoroughly designed longitudinal studies are necessary for revealing the cause-effect relationship of work stress, epigenetics and burnout, including its overlap with depression. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Mechanical-magnetic-electric coupled behaviors for stress-driven Terfenol-D energy harvester

    Directory of Open Access Journals (Sweden)

    Shuying Cao

    2017-05-01

    Full Text Available The stress-driven Terfernol-D energy harvester exhibits the nonlinear mechanical-magnetic-electric coupled (MMEC behaviors and the eddy current effects. To analyze and design the device, it is necessary to establish an accurate model of the device. Based on the effective magnetic field expression, the constitutive equations with eddy currents and variable coefficients, and the dynamic equations, a nonlinear dynamic MMEC model for the device is founded. Comparisons between the measured and calculated results show that the model can describe the nonlinear coupled curves of magnetization versus stress and strain versus stress under different bias fields, and can provide the reasonable data trends of piezomagnetic coefficients, Young’s modulus and relative permeability for Terfenol-D. Moreover, the calculated power results show that the model can determine the optimal bias conditions, optimal resistance, suitable proof mass, suitable slices for the maximum energy extraction of the device under broad stress amplitude and broad frequency.

  17. Oxidative Stress-Mediated Skeletal Muscle Degeneration: Molecules, Mechanisms, and Therapies

    Directory of Open Access Journals (Sweden)

    Min Hee Choi

    2016-01-01

    Full Text Available Oxidative stress is a loss of balance between the production of reactive oxygen species during cellular metabolism and the mechanisms that clear these species to maintain cellular redox homeostasis. Increased oxidative stress has been associated with muscular dystrophy, and many studies have proposed mechanisms that bridge these two pathological conditions at the molecular level. In this review, the evidence indicating a causal role of oxidative stress in the pathogenesis of various muscular dystrophies is revisited. In particular, the mediation of cellular redox status in dystrophic muscle by NF-κB pathway, autophagy, telomere shortening, and epigenetic regulation are discussed. Lastly, the current stance of targeting these pathways using antioxidant therapies in preclinical and clinical trials is examined.

  18. [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.

  19. Utilization of Different Omic Approaches to Unravel Stress Response Mechanisms in the Parasite Entamoeba histolytica

    Directory of Open Access Journals (Sweden)

    Shruti Nagaraja

    2018-02-01

    Full Text Available During its life cycle, the unicellular parasite Entamoeba histolytica is challenged by a wide variety of environmental stresses, such as fluctuation in glucose concentration, changes in gut microbiota composition, and the release of oxidative and nitrosative species from neutrophils and macrophages. The best mode of survival for this parasite is to continuously adapt itself to the dynamic environment of the host. Our ability to study the stress-induced responses and adaptive mechanisms of this parasite has been transformed through the development of genomics, proteomics or metabolomics (omics sciences. These studies provide insights into different facets of the parasite's behavior in the host. However, there is a dire need for multi-omics data integration to better understand its pathogenic nature, ultimately paving the way to identify new chemotherapeutic targets against amebiasis. This review provides an integration of the most relevant omics information on the mechanisms that are used by E. histolytica to resist environmental stresses.

  20. Mechanical Characterization of Thermomechanical Matrix Residual Stresses Incurred During MMC Processing

    Science.gov (United States)

    Castelli, Michael G.

    1998-01-01

    In recent years, much effort has been spent examining the residual stress-strain states of advanced composites. Such examinations are motivated by a number of significant concerns that affect composite development, processing, and analysis. The room-temperature residual stress states incurred in many advanced composite systems are often quite large and can introduce damage even prior to the first external mechanical loading of the material. These stresses, which are induced during the cooldown following high-temperature consolidation, result from the coefficient of thermal expansion mismatch between the fiber and matrix. Experimental techniques commonly used to evaluate composite internal residual stress states are non-mechanical in nature and generally include forms of x-ray and neutron diffraction. Such approaches are usually complex, involving a number of assumptions and limitations associated with a wide range of issues, including the depth of penetration, the volume of material being assessed, and erroneous effects associated with oriented grains. Furthermore, and more important to the present research, these techniques can assess only "single time" stress in the composite. That is, little, if any, information is obtained that addresses the time-dependent point at which internal stresses begin to accumulate, the manner in which the accumulation occurs, and the presiding relationships between thermoelastic, thermoplastic, and thermoviscous behaviors. To address these critical issues, researchers at the NASA Lewis Research Center developed and implemented an innovative mechanical test technique to examine in real time, the time-dependent thermomechanical stress behavior of a matrix alloy as it went through a consolidation cycle.

  1. Shedding Light on the Mechanisms Underlying Health Disparities Through Community Participatory Methods: The Stress Pathway

    Science.gov (United States)

    Schetter, Christine Dunkel; Schafer, Peter; Lanzi, Robin Gaines; Clark-Kauffman, Elizabeth; Raju, Tonse N. K.; Hillemeier, Marianne M.

    2015-01-01

    Health disparities are large and persistent gaps in the rates of disease and death between racial/ethnic and socioeconomic status subgroups in the population. Stress is a major pathway hypothesized to explain such disparities. The Eunice Kennedy Shriver National Institute of Child Health and Human Development formed a community/research collaborative—the Community Child Health Network—to investigate disparities in maternal and child health in five high-risk communities. Using community participation methods, we enrolled a large cohort of African American/Black, Latino/Hispanic, and non-Hispanic/White mothers and fathers of newborns at the time of birth and followed them over 2 years. A majority had household incomes near or below the federal poverty level. Home interviews yielded detailed information regarding multiple types of stress such as major life events and many forms of chronic stress including racism. Several forms of stress varied markedly by racial/ethnic group and income, with decreasing stress as income increased among Caucasians but not among African Americans; other forms of stress varied by race/ethnicity or poverty alone. We conclude that greater sophistication in studying the many forms of stress and community partnership is necessary to uncover the mechanisms underlying health disparities in poor and ethnic-minority families and to implement community health interventions. PMID:26173227

  2. Mechanical Stress Downregulates MHC Class I Expression on Human Cancer Cell Membrane

    DEFF Research Database (Denmark)

    La Rocca, Rosanna; Tallerico, Rossana; Hassan, Almosawy Talib

    2014-01-01

    In our body, cells are continuously exposed to physical forces that can regulate different cell functions such as cell proliferation, differentiation and death. In this work, we employed two different strategies to mechanically stress cancer cells. The cancer and healthy cell populations were tre...

  3. Causes of excitation-induced muscle cell damage in isometric contractions: mechanical stress or calcium overload?

    DEFF Research Database (Denmark)

    Fredsted, Anne; Gissel, Hanne; Madsen, Klavs

    2007-01-01

    Prolonged or unaccustomed exercise leads to muscle cell membrane damage, detectable as release of the intracellular enzyme lactic acid dehydrogenase (LDH). This is correlated to excitation-induced influx of Ca2+, but it cannot be excluded that mechanical stress contributes to the damage. We here ...

  4. Clonal plasticity of aquatic plant species submitted to mechanical stress: escape versus resistance strategy

    NARCIS (Netherlands)

    Puijalon, S.; Bouma, T.J.; Van Groenendael, J.M.; Bornette, G.

    2008-01-01

    Background and Aims: The plastic alterations of clonal architecture are likely to have functional consequences, as they affect the spatial distribution of ramets over patchy environments. However, little is known about the effect of mechanical stresses on the clonal growth. The aim of the present

  5. The influence of initial defects on mechanical stress and deformation distribution in oxidized silicon

    Directory of Open Access Journals (Sweden)

    Kulinich O. A.

    2008-10-01

    Full Text Available The near-surface silicon layers in silicon – dioxide silicon systems with modern methods of research are investigated. It is shown that these layers have compound structure and their parameters depend on oxidation and initial silicon parameters. It is shown the influence of initial defects on mechanical stress and deformation distribution in oxidized silicon.

  6. Interpersonal Stress Generation as a Mechanism Linking Rumination to Internalizing Symptoms in Early Adolescents

    Science.gov (United States)

    McLaughlin, Katie A.; Nolen-Hoeksema, Susan

    2012-01-01

    Rumination is a risk factor for depressive and anxiety symptoms in adolescents. Previous investigations of the mechanisms linking rumination to internalizing problems have focused primarily on cognitive factors. We investigated whether interpersonal stress generation plays a role in the longitudinal relationship between rumination and…

  7. Comparison of bruises ad mortality, stress parameters, and meat quality in manually and mechanically caught broilers.

    NARCIS (Netherlands)

    Nijdam, E.; Delezie, E.; Lambooij, E.; Nabuurs, M.J.A.; Decuypere, M.P.; Stegeman, J.A.

    2005-01-01

    A field trial was conducted to compare manual catching of broilers with a mechanical catching method. Both methods were compared with respect to the incidence of bruises and dead on arrival, stress parameters, and meat quality. Also the dynamics of corticosterone, glucose, and lactate were

  8. Endogenous reward mechanisms and their importance in stress reduction, exercise and the brain

    Science.gov (United States)

    Stefano, George B.

    2010-01-01

    Stress can facilitate disease processes and causes strain on the health care budgets. It is responsible or involved in many human ailments of our time, such as cardiovascular illnesses, particularly related to the psychosocial stressors of daily life, including work. Besides pharmacological or clinical medical treatment options, behavioral stress reduction is much-needed. These latter approaches rely on an endogenous healing potential via life-style modification. Hence, research has suggested different ways and approaches to self-treat stress or buffer against stressors and their impacts. These self-care-centred approaches are sometimes referred to as mind-body medicine or multi-factorial stress management strategies. They consist of various cognitive behavioral techniques, as well as relaxation exercises and nutritional counselling. However, a critical and consistent element of modern effective stress reduction strategies are exercise practices. With regard to underlying neurobiological mechanisms of stress relief, reward and motivation circuitries that are imbedded in the limbic regions of the brain are responsible for the autoregulatory and endogenous processing of stress. Exercise techniques clearly have an impact upon these systems. Thereby, physical activities have a potential to increase mood, i.e., decrease psychological distress by pleasure induction. For doing so, neurobiological signalling molecules such as endogenous morphine and coupled nitric oxide pathways get activated and finely tuned. Evolutionarily, the various activities and autoregulatory pathways are linked together, which can also be demonstrated by the fact that dopamine is endogenously converted into morphine which itself leads to enhanced nitric oxide release by activation of constitutive nitric oxide synthase enzymes. These molecules and mechanisms are clearly stress-reducing. PMID:22371784

  9. Endogenous reward mechanisms and their importance in stress reduction, exercise and the brain.

    Science.gov (United States)

    Esch, Tobias; Stefano, George B

    2010-06-30

    Stress can facilitate disease processes and causes strain on the health care budgets. It is responsible or involved in many human ailments of our time, such as cardiovascular illnesses, particularly related to the psychosocial stressors of daily life, including work. Besides pharmacological or clinical medical treatment options, behavioral stress reduction is much-needed. These latter approaches rely on an endogenous healing potential via life-style modification. Hence, research has suggested different ways and approaches to self-treat stress or buffer against stressors and their impacts. These self-care-centred approaches are sometimes referred to as mind-body medicine or multi-factorial stress management strategies. They consist of various cognitive behavioral techniques, as well as relaxation exercises and nutritional counselling. However, a critical and consistent element of modern effective stress reduction strategies are exercise practices. With regard to underlying neurobiological mechanisms of stress relief, reward and motivation circuitries that are imbedded in the limbic regions of the brain are responsible for the autoregulatory and endogenous processing of stress. Exercise techniques clearly have an impact upon these systems. Thereby, physical activities have a potential to increase mood, i.e., decrease psychological distress by pleasure induction. For doing so, neurobiological signalling molecules such as endogenous morphine and coupled nitric oxide pathways get activated and finely tuned. Evolutionarily, the various activities and autoregulatory pathways are linked together, which can also be demonstrated by the fact that dopamine is endogenously converted into morphine which itself leads to enhanced nitric oxide release by activation of constitutive nitric oxide synthase enzymes. These molecules and mechanisms are clearly stress-reducing.

  10. Maize water status and physiological traits as affected by root endophytic fungus Piriformospora indica under combined drought and mechanical stresses.

    Science.gov (United States)

    Hosseini, Fatemeh; Mosaddeghi, Mohammad Reza; Dexter, Anthony Roger; Sepehri, Mozhgan

    2018-02-16

    Under combined drought and mechanical stresses, mechanical stress primarily controlled physiological responses of maize. Piriformospora indica mitigated the adverse effects of stresses, and inoculated maize experienced less oxidative damage and had better adaptation to stressful conditions. The objective of this study was to investigate the effect of maize root colonization by an endophytic fungus P. indica on plant water status, physiological traits and root morphology under combined drought and mechanical stresses. Seedlings of inoculated and non-inoculated maize (Zea mays L., cv. single cross 704) were cultivated in growth chambers filled with moistened siliceous sand at a matric suction of 20 hPa. Drought stress was induced using PEG 6000 solution with osmotic potentials of 0, - 0.3 and - 0.5 MPa. Mechanical stress (i.e., penetration resistances of 1.05, 4.23 and 6.34 MPa) was exerted by placing weights on the surface of the sand medium. After 30 days, leaf water potential (LWP) and relative water content (RWC), root and shoot fresh weights, root volume (RV) and diameter (RD), leaf proline content, leaf area (LA) and catalase (CAT) and ascorbate peroxidase (APX) activities were measured. The results show that exposure to individual drought and mechanical stresses led to higher RD and proline content and lower plant biomass, RV and LA. Moreover, increasing drought and mechanical stress severity increased APX activity by about 1.9- and 3.1-fold compared with the control. When plants were exposed to combined stresses, mechanical stress played the dominant role in controlling plant responses. P. indica-inoculated plants are better adapted to individual and combined stresses. The inoculated plants had greater RV, LA, RWC, LWP and proline content under stressful conditions. In comparison with non-inoculated plants, inoculated plants showed lower CAT and APX activities which means that they experienced less oxidative stress induced by stressful conditions.

  11. CDM (Clean development mechanism) like instrument for sustainable development?; MDL (mecanismo de desenvolvimento limpo) como instrumento para o desenvolvimento sustentavel?

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, Kamyla Borges da; Walter, Arnaldo Cesar Silva; Varella, Fabiana Karla de Oliveira; Streb, Cleci Schalemberger [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Fac. de Engenharia Mecanica. Curso de Pos-Graduaco em Planejamento de Sistemas Energeticos], e-mail: kamyla@fem.unicamp.br

    2004-07-01

    The intensification of the greenhouse effect, caused mainly by the anthropogenic activities, such as the intensive use of fossil fuels, reveals itself as a challenge to governments and international organizations. The institution of an international legal framework, resulted from the implementation of the United Nations Framework Convention on Climate Change and the Kyoto Protocol, is allowing the development of some mitigation instruments, such as the clean development mechanism (CDM). The article's purpose is to assess the social and economic aspects that are leading to the climate change process and to analyze the instruments foreseen in the international legal system to face this global concern, in special, the CDM as a tool to achieve sustainable development practices. In this way, the authors aims to demonstrate the connection and interdependence between those instruments and the sustainable development. (author)

  12. Sustained anxiety increases amygdala–dorsomedial prefrontal coupling: a mechanism for maintaining an anxious state in healthy adults

    Science.gov (United States)

    Vytal, Katherine E.; Overstreet, Cassie; Charney, Danielle R.; Robinson, Oliver J.; Grillon, Christian

    2014-01-01

    Background Neuroimaging research has traditionally explored fear and anxiety in response to discrete threat cues (e.g., during fear conditioning). However, anxiety is a sustained aversive state that can persist in the absence of discrete threats. Little is known about mechanisms that maintain anxiety states over a prolonged period. Here, we used a robust translational paradigm (threat of shock) to induce sustained anxiety. Recent translational work has implicated an amygdala–prefrontal cortex (PFC) circuit in the maintenance of anxiety in rodents. To explore the functional homologues of this circuitry in humans, we used a novel paradigm to examine the impact of sustained anticipatory anxiety on amygdala–PFC intrinsic connectivity. Methods Task-independent fMRI data were collected in healthy participants during long-duration periods of shock anticipation and safety. We examined intrinsic functional connectivity. Results Our study involved 20 healthy participants. During sustained anxiety, amygdala activity was positively coupled with dorsomedial PFC (DMPFC) activity. High trait anxiety was associated with increased amygdala–DMPFC coupling. In addition, induced anxiety was associated with positive coupling between regions involved in defensive responding, and decreased coupling between regions involved in emotional control and the default mode network. Limitations Inferences regarding anxious pathology should be made with caution because this study was conducted in healthy participants. Conclusion Findings suggest that anticipatory anxiety increases intrinsic amygdala–DMPFC coupling and that the DMPFC may serve as a functional homologue for the rodent prefrontal regions by sustaining anxiety. Future research may use this defensive neural context to identify bio-markers of risk for anxious pathology and target these circuits for therapeutic intervention. PMID:24886788

  13. Perspectives on deciphering mechanisms underlying plant heat stress response and thermotolerance

    Directory of Open Access Journals (Sweden)

    Kamila Lucia Bokszczanin

    2013-08-01

    Full Text Available Global warming is a major threat for agriculture and food safety and in many cases the negative effects are already apparent. The current challenge of basic and applied plant science is to decipher the molecular mechanisms of heat stress response and thermotolerance in detail and use this information to identify genotypes that will withstand unfavorable environmental conditions. Nowadays X-omics approaches complement the findings of previous targeted studies and highlight the complexity of heat stress response mechanisms giving information for so far unrecognized genes, proteins and metabolites as potential key players of thermotolerance. Even more, roles of epigenetic mechanisms and the involvement of small RNAs in thermotolerance are currently emerging and thus open new directions of yet unexplored areas of plant heat stress response. In parallel it is emerging that although the whole plant is vulnerable to heat, specific organs are particularly sensitive to elevated temperatures. This has redirected research from the vegetative to generative tissues. The sexual reproduction phase is considered as the most sensitive to heat and specifically pollen exhibits the highest sensitivity and frequently an elevation of the temperature just a few degrees above the optimum during pollen development can have detrimental effects for crop production. Compared to our knowledge on heat stress response of vegetative tissues, the information on pollen is still scarce. Nowadays, several techniques for high-throughput X-omics approaches provide major tools to explore the principles of pollen heat stress response and thermotolerance mechanisms in specific genotypes. The collection of such information will provide an excellent support for improvement of breeding programs to facilitate the development of tolerant cultivars. The review aims at describing the current knowledge of thermotolerance mechanisms and the technical advances which will foster new insights into

  14. Evaluating chemical-, mechanical-, and bio-pulping processes and their sustainability characterization using life cycle assessment

    Science.gov (United States)

    Tapas K. Das; Carl Houtman

    2004-01-01

    Pulp and paper manufacturing constitutes one of the largest industry segments in the United States in term of water and energy usage and total discharges to the environment. More than many other industries, however, this industry plays an important role in sustainable development because its chief raw material— wood fiber—is renewable. This industry provides an example...

  15. Electricity Pricing Mechanism in a Sustainable Environment: A Review and a System Dynamics Modeling Approach

    OpenAIRE

    Tziogas, C; Georgiadis, P; Tsolakis, N; Yakinthos, C

    2017-01-01

    Electricity is an undisputed factor supporting human development, while further supporting social wellbeing and fostering economic growth of modern societies. Therefore, the electricity market provides a vivid policy-making arena for the EU regulators, where on-going structural reforms are promoted with the aim to encapsulate and accommodate sustainability aspects. Notably, the EU Member States have adopted the strategic roadmap “Europe 2020” toward reducing greenhouse gas emissions and energ...

  16. Expression of HSPs: an adaptive mechanism during long-term heat stress in goats ( Capra hircus)

    Science.gov (United States)

    Dangi, Satyaveer Singh; Gupta, Mahesh; Dangi, Saroj K.; Chouhan, Vikrant Singh; Maurya, V. P.; Kumar, Puneet; Singh, Gyanendra; Sarkar, Mihir

    2015-08-01

    Menacing global rise in surface temperature compelled more focus of research over understanding heat stress response mechanism of animals and mitigation of heat stress. Twenty-four goats divided into four groups ( n = 6) such as NHS (non-heat-stressed), HS (heat-stressed), HS + VC (heat-stressed administered with vitamin C), and HS + VE + Se (heat-stressed administered with vitamin E and selenium). Except NHS group, other groups were exposed to repeated heat stress (42 °C) for 6 h on 16 consecutive days. Blood samples were collected at the end of heat exposure on days 1, 6, 11, and 16. When groups compared between days, expression of all heat shock proteins (HSPs) showed a similar pattern as first peak on day 1, reached to basal level on the sixth day, and followed by second peak on day 16. The relative messenger RNA (mRNA) and protein expression of HSP 60, HSP70, and HSP90 was observed highest ( P < 0.05) in HS group, followed by antioxidant-administered group on days 1 and 16, which signifies that antioxidants have dampening effect on HSP expression. HSP105/110 expression was highest ( P < 0.05) on day 16. We conclude that HSP expression pattern is at least two-peak phenomenon, i.e., primary window of HSP protection on the first day followed by second window of protection on day 16. HSP60, HSP70, and HSP90 play an important role during the initial phase of heat stress acclimation whereas HSP105/110 joins this cascade at later phase. Antioxidants may possibly attenuate the HSP expression by reducing the oxidative stress.

  17. Cellular and exosome mediated molecular defense mechanism in bovine granulosa cells exposed to oxidative stress.

    Science.gov (United States)

    Saeed-Zidane, Mohammed; Linden, Lea; Salilew-Wondim, Dessie; Held, Eva; Neuhoff, Christiane; Tholen, Ernst; Hoelker, Michael; Schellander, Karl; Tesfaye, Dawit

    2017-01-01

    Various environmental insults including diseases, heat and oxidative stress could lead to abnormal growth, functions and apoptosis in granulosa cells during ovarian follicle growth and oocyte maturation. Despite the fact that cells exposed to oxidative stress are responding transcriptionally, the potential release of transcripts associated with oxidative stress response into extracellular space through exosomes is not yet determined. Therefore, here we aimed to investigate the effect of oxidative stress in bovine granulosa cells in vitro on the cellular and exosome mediated defense mechanisms. Bovine granulosa cells were aspirated from ovarian follicles and cultured in DMEM/F-12 Ham culture medium supplemented with 10% exosome-depleted fetal bovine serum. In the first experiment sub-confluent cells were treated with 5 μM H2O2 for 40 min to induce oxidative stress. Thereafter, cells were subjected to ROS and mitochondrial staining, cell proliferation and cell cycle assays. Furthermore, gene and protein expression analysis were performed in H2O2-challenged versus control group 24 hr post-treatment using qRT-PCR and immune blotting or immunocytochemistry assay, respectively. Moreover, exosomes were isolated from spent media using ultracentrifugation procedure, and subsequently used for RNA isolation and qRT-PCR. In the second experiment, exosomes released by granulosa cells under oxidative stress (StressExo) or those released by granulosa cells without oxidative stress (NormalExo) were co-incubated with bovine granulosa cells in vitro to proof the potential horizontal transfer of defense molecules from exosomes to granulosa cells and investigate any phenotype changes. Exposure of bovine granulosa cells to H2O2 induced the accumulation of ROS, reduced mitochondrial activity, increased expression of Nrf2 and its downstream antioxidant genes (both mRNA and protein), altered the cell cycle transitions and induced cellular apoptosis. Granulosa cells exposed to oxidative

  18. Dissolution Condensation Mechanism of Stress Corrosion Cracking in Liquid Metals: Driving Force and Crack Kinetics

    Science.gov (United States)

    Glickman, Evgeny E.

    2011-02-01

    Stress corrosion cracking (SCC) in aqueous solution is driven by exothermic reactions of metal oxidation. This stimulus, as well as classical mechanisms of SCC, does not apply to SCC in liquid metals (LMs). In the framework of the dissolution-condensation mechanism (DCM), we analyzed the driving force and crack kinetics for this nonelectrochemical mode of SCC that is loosely called "liquid metal embrittlement" (LME). According to DCM, a stress-induced increase in chemical potential at the crack tip acts as the driving force for out-of-the-tip diffusion mass transfer that is fast because diffusion in LMs is very fast and surface energy at the solid-liquid interface is small. In this article, we review two versions of DCM mechanism, discuss the major physics behind them, and develop DCM further. The refined mechanism is applied then to the experimental data on crack velocity V vs stress intensity factor, the activation energy of LME, and alloying effects. It is concluded that DCM provides a good conceptual framework for analysis of a unified kinetic mechanism of LME and may also contribute to SCC in aqueous solutions.

  19. More cells, bigger cells or simply reorganization? Alternative mechanisms leading to changed internode architecture under contrasting stress regimes

    NARCIS (Netherlands)

    Huber, Heidrun; de Brouwer, Jan; von Wettberg, Eric J.; During, Heinjo J.|info:eu-repo/dai/nl/068848625; Anten, Niels P. R.|info:eu-repo/dai/nl/138797862

    Shading and mechanical stress (MS) modulate plant architecture by inducing different developmental pathways. Shading results in increased stem elongation, often reducing whole-plant mechanical stability, while MS inhibits elongation, with a concomitant increase in stability. Here, we examined how

  20. More cells, bigger cells or simply reorganization? Alternative mechanisms leading to changed internode architecture under contrasting stress regimes

    NARCIS (Netherlands)

    Huber, H.; Brouwer, de J.H.F.; Wettberg, von E.J.; During, H.J.; Anten, N.P.R.

    2014-01-01

    Shading and mechanical stress (MS) modulate plant architecture by inducing different developmental pathways. Shading results in increased stem elongation, often reducing whole-plant mechanical stability, while MS inhibits elongation, with a concomitant increase in stability. Here, we examined how

  1. Oxidative Stress-Related Mechanisms and Antioxidant Therapy in Diabetic Retinopathy

    Directory of Open Access Journals (Sweden)

    Cheng Li

    2017-01-01

    Full Text Available Diabetic retinopathy (DR is one of the most common microvascular complications of diabetes and is the leading cause of blindness in young adults. Oxidative stress has been implicated as a critical cause of DR. Metabolic abnormalities induced by high-glucose levels are involved in the development of DR and appear to be influenced by oxidative stress. The imbalance between reactive oxygen species (ROS production and the antioxidant defense system activates several oxidative stress-related mechanisms that promote the pathogenesis of DR. The damage caused by oxidative stress persists for a considerable time, even after the blood glucose concentration has returned to a normal level. Animal experiments have proved that the use of antioxidants is a beneficial therapeutic strategy for the treatment of DR, but more data are required from clinical trials. The aims of this review are to highlight the improvements to our understanding of the oxidative stress-related mechanisms underlying the development of DR and provide a summary of the main antioxidant therapy strategies used to treat the disease.

  2. Human serum albumin and oxidative stress in preeclamptic women and the mechanism of albumin for stress reduction.

    Science.gov (United States)

    Kinoshita, Hiroyuki; Watanabe, Kazushi; Azma, Toshiharu; Feng, Guo-Gang; Akahori, Takahiko; Hayashi, Hisaki; Sato, Motohiko; Fujiwara, Yoshihiro; Wakatsuki, Akihiko

    2017-08-01

    The present study to address one of the mechanisms in preeclampsia, examined whether levels of oxidative stress, human serum albumin, and endothelial function correlate in pregnant women and whether human serum albumin reduces levels of superoxide produced by NADPH oxidase activation in the human vascular smooth muscle cells. Pregnant women with (Preeclampsia group, n = 33) and without preeclampsia (Normal group, n = 37) were recruited to determine levels of reactive oxygen species (serum diacron-reactive oxygen metabolite [d-ROM]), and the flow-mediated dilation (FMD). Human coronary arterial smooth muscle cells or omental arteries were subjected to evaluate isometric force recordings, levels of superoxide, western immunoblotting, and immunohistochemistry. The superoxide scavenging assay was also performed in a cell-free system. Women in the preeclampsia group demonstrated lower FMD and higher serum d-ROM values than those in the normal group. There were the inverse correlations between serum levels of d-ROM and the degree of FMD and between serum levels of albumin and those of d-ROM. D-glucose reduced the levcromakalim-induced dilation of human omental arteries, and it increased levels of superoxide and the recruitment of the NADPH oxidase subunit p47phox in human coronary arterial smooth muscle cells. Human serum albumin (0.05 to 0.5 g/dL) prevented these alterations whereas it exerted no superoxide scavenging effect. Serum albumin relates to oxidative stress inversely, but to the endothelial function positively, in pregnant women. Human serum albumin appears to reduce oxidative stress via NADPH oxidase inhibition in the human vascular smooth muscle, indicating that the serum level may be a critical determinant of vascular oxidative stress in some human diseases.

  3. Elastic stress transmission and transformation (ESTT) by confined liquid: A new mechanics for fracture in elastic lithosphere of the earth

    Science.gov (United States)

    Xu, Xing-Wang; Peters, Stephen; Liang, Guang-He; Zhang, Bao-Lin

    2016-01-01

    We report on a new mechanical principle, which suggests that a confined liquid in the elastic lithosphere has the potential to transmit a maximum applied compressive stress. This stress can be transmitted to the internal contacts between rock and liquid and would then be transformed into a normal compressive stress with tangential tensile stress components. During this process, both effective compressive normal stress and tensile tangential stresses arise along the liquid–rock contact. The minimum effective tensile tangential stress causes the surrounding rock to rupture. Liquid-driven fracture initiates at the point along the rock–liquid boundary where the maximum compressive stress is applied and propagates along a plane that is perpendicular to the minimum effective tensile tangential stress and also is perpendicular to the minimum principal stress.

  4. Mechanisms of food processing and storage-related stress tolerance in Clostridium botulinum.

    Science.gov (United States)

    Dahlsten, Elias; Lindström, Miia; Korkeala, Hannu

    2015-05-01

    Vegetative cultures of Clostridium botulinum produce the extremely potent botulinum neurotoxin, and may jeopardize the safety of foods unless sufficient measures to prevent growth are applied. Minimal food processing relies on combinations of mild treatments, primarily to avoid deterioration of the sensory qualities of the food. Tolerance of C. botulinum to minimal food processing is well characterized. However, data on effects of successive treatments on robustness towards further processing is lacking. Developments in genetic manipulation tools and the availability of annotated genomes have allowed identification of genetic mechanisms involved in stress tolerance of C. botulinum. Most studies focused on low temperature, and the importance of various regulatory mechanisms in cold tolerance of C. botulinum has been demonstrated. Furthermore, novel roles in cold tolerance were shown for metabolic pathways under the control of these regulators. A role for secondary oxidative stress in tolerance to extreme temperatures has been proposed. Additionally, genetic mechanisms related to tolerance to heat, low pH, and high salinity have been characterized. Data on genetic stress-related mechanisms of psychrotrophic Group II C. botulinum strains are scarce; these mechanisms are of interest for food safety research and should thus be investigated. This minireview encompasses the importance of C. botulinum as a food safety hazard and its central physiological characteristics related to food-processing and storage-related stress. Special attention is given to recent findings considering genetic mechanisms C. botulinum utilizes in detecting and countering these adverse conditions. Copyright © 2014 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  5. Mechanism of oxidative stress involved in the toxicity of ZnO nanoparticles against eukaryotic cells

    Directory of Open Access Journals (Sweden)

    M. Saliani

    2016-01-01

    Full Text Available ZnO NPs (zinc oxide nanoparticles has generated significant scientific interest as a novel antibacterial and anticancer agent. Since oxidative stress is a critical determinant of ZnO NPs-induced damage, it is necessary to characterize their underlying mode of action. Different structural and physicochemical properties of ZnO NPs such as particle surface, size, shape, crystal structure, chemical position, and presence of metals can lead to changes in biological activities including ROS (reactive oxygen species production. However, there are some inconsistencies in the literature on the relation between the physicochemical features of ZnO NPs and their plausible oxidative stress mechanism. Herein, the possible oxidative stress mechanism of ZnO NPs was reviewed. This is worthy of further detailed evaluations in order to improve our understanding of vital NPs characteristics governing their toxicity. Therefore, this study focuses on the different reported oxidative stress paradigms induced by ZnO NPs including ROS generated by NPs, oxidative stress due to the NPs-cell interaction, and role of the particle dissolution in the oxidative damage. Also, this study tries to characterize and understand the multiple pathways involved in oxidative stress induced by ZnO NPs. Knowledge about different cellular signaling cascades stimulated by ZnO NPs lead to the better interpretation of the toxic influences induced by the cellular and acellular parameters. Regarding the potential benefits of toxic effects of ZnO NPs, in-depth evaluation of their toxicity mechanism and various effects of these nanoparticles would facilitate their implementation for biomedical applications.

  6. Microarray analysis of regional cellular responses to local mechanical stress in acute lung injury.

    Science.gov (United States)

    Simon, Brett A; Easley, R Blaine; Grigoryev, Dmitry N; Ma, Shwu-Fan; Ye, Shui Q; Lavoie, Tera; Tuder, Rubin M; Garcia, Joe G N

    2006-11-01

    Human acute lung injury is characterized by heterogeneous tissue involvement, leading to the potential for extremes of mechanical stress and tissue injury when mechanical ventilation, required to support critically ill patients, is employed. Our goal was to establish whether regional cellular responses to these disparate local mechanical conditions could be determined as a novel approach toward understanding the mechanism of development of ventilator-associated lung injury. We utilized cross-species genomic microarrays in a unilateral model of ventilator-associated lung injury in anesthetized dogs to assess regional cellular responses to local mechanical conditions that potentially contribute pathogenic mechanisms of injury. Highly significant regional differences in gene expression were observed between lung apex/base regions as well as between gravitationally dependent/nondependent regions of the base, with 367 and 1,544 genes differentially regulated between these regions, respectively. Major functional groupings of differentially regulated genes included inflammation and immune responses, cell proliferation, adhesion, signaling, and apoptosis. Expression of genes encoding both acute lung injury-associated inflammatory cytokines and protective acute response genes were markedly different in the nondependent compared with the dependent regions of the lung base. We conclude that there are significant differences in the local responses to stress within the lung, and consequently, insights into the cellular responses that contribute to ventilator-associated lung injury development must be sought in the context of the mechanical heterogeneity that characterizes this syndrome.

  7. Investigation of the impact of mechanical stress on the properties of silicon strip sensors

    CERN Document Server

    Affolder, Tony; The ATLAS collaboration

    2017-01-01

    The new ATLAS tracker for phase II will be composed of silicon pixel and strip sensor modules. The strip sensor module consists of silicon sensors, boards and readout chips. Adhesives are used to connect the modular components thermally and mechanically. It was shown that the silicon sensor is exposed to mechanical stress, due to temperature difference between construction and operation. Mechanical stress can damage the sensor and can change the electrical properties. The thermal induced tensile stress near to the surface of a silicon sensor in a module was simulated and the results are compared to a cooled module. A four point bending setup was used to measure the maximum tensile stress of silicon detectors and to verify the piezoresistive effects on two recent development sensor types used in ATLAS (ATLAS07 and ATLAS12). Changes in the interstrip, bulk and bias resistance and capacitance as well as the coupling capacitance and the implant resistance were measured. The Leakage current was observed to decreas...

  8. Stress Induced Mechano-electrical Writing-Reading of Polymer Film Powered by Contact Electrification Mechanism

    Science.gov (United States)

    Goswami, Sumita; Nandy, Suman; Calmeiro, Tomás R.; Igreja, Rui; Martins, Rodrigo; Fortunato, Elvira

    2016-01-01

    Mechano-electrical writing and reading in polyaniline (PANI) thin film are demonstrated via metal-polymer contact electrification mechanism (CEM). An innovative conception for a non-destructive self-powered writable-readable data sheet is presented which can pave the way towards new type of stress induced current harvesting devices. A localized forced deformation of the interface has been enacted by pressing the atomic force microscopic probe against the polymer surface, allowing charge transfer between materials interfaces. The process yields a well-defined charge pattern by transmuting mechanical stress in to readable information. The average of output current increment has been influenced from 0.5 nA to 15 nA for the applied force of 2 nN to 14 nN instead of electrical bias. These results underscore the importance of stress-induced current harvesting mechanism and could be scaled up for charge patterning of polymer surface to writable-readable data sheet. Time evolutional current distribution (TECD) study of the stress-induced patterned PANI surface shows the response of readability of the recorded data with time.

  9. Genetic mechanism for building evolution reflecting stress histories of residents and environmental factors

    Science.gov (United States)

    Nishikawa, Saya; Mita, Akira

    2014-03-01

    Conventional architectural design has a lot to do with the intuition and experience of designers. And residences are not always suit to its residents and surrounding environment. If we can extract residents' preferences and demands about comfort of each resident from histories of past life and reflect these information in next design, it's possible to make living space more comfortable. This thesis proposes genetic and evolutional system for architectural design information, which is applied evolutionary adaption. Specifically, I applied genetic mechanism which base sequence of DNA plays a role, epigenetic mechanism which chemical modification plays a role and evolutionary mechanism with natural selection. Proposed system firstly accumulates discomfort of residents, shortcoming of living space and usage of equipment as "comfort stress", "safety stress" and "energy saving stress", and modifies performance value of related performance items of building depending on the stress accumulation. Then this system processes selection according to the characteristics of the site for candidates of next generation of architectural design information which are generated via crossing and mutation. The data-set selected in this way is regarded as the performance value of next architectural design, and system suggests architectural specification to the residents.

  10. Preventive Effects of Poloxamer 188 on Muscle Cell Damage Mechanics Under Oxidative Stress.

    Science.gov (United States)

    Wong, Sing Wan; Yao, Yifei; Hong, Ye; Ma, Zhiyao; Kok, Stanton H L; Sun, Shan; Cho, Michael; Lee, Kenneth K H; Mak, Arthur F T

    2017-04-01

    High oxidative stress can occur during ischemic reperfusion and chronic inflammation. It has been hypothesized that such oxidative challenges could contribute to clinical risks such as deep tissue pressure ulcers. Skeletal muscles can be challenged by inflammation-induced or reperfusion-induced oxidative stress. Oxidative stress reportedly can lower the compressive damage threshold of skeletal muscles cells, causing actin filament depolymerization, and reduce membrane sealing ability. Skeletal muscles thus become easier to be damaged by mechanical loading under prolonged oxidative exposure. In this study, we investigated the preventive effect of poloxamer 188 (P188) on skeletal muscle cells against extrinsic oxidative challenges (H2O2). It was found that with 1 mM P188 pre-treatment for 1 h, skeletal muscle cells could maintain their compressive damage threshold. The actin polymerization dynamics largely remained stable in term of the expression of cofilin, thymosin beta 4 and profilin. Laser photoporation demonstrated that membrane sealing ability was preserved even as the cells were challenged by H2O2. These findings suggest that P188 pre-treatment can help skeletal muscle cells retain their normal mechanical integrity in oxidative environments, adding a potential clinical use of P188 against the combined challenge of mechanical-oxidative stresses. Such effect may help to prevent deep tissue ulcer development.

  11. Toward an understanding of mechanism of aging-induced oxidative stress in human mesenchymal stem cells.

    Science.gov (United States)

    Benameur, Laila; Charif, Naceur; Li, Yueying; Stoltz, Jean-François; de Isla, Natalia

    2015-01-01

    Under physiological conditions, there is a production of limited range of free radicals. However, when the cellular antioxidant defence systems, overwhelm and fail to reverse back the free radicals to their normal basal levels, there is a creation of a condition of redox disequilibrium termed "oxidative stress", which is implicated in a very wide spectrum of genetic, metabolic, and cellular responses. The excess of free radicals can, cause unfavourable molecular alterations to biomolecules through oxidation of lipids, proteins, RNA and DNA, that can in turn lead to mutagenesis, carcinogenesis, and aging. Mesenchymal stem cells (MSCs) have been proven to be a promising source of cells for regenerative medicine, and to be useful in the treatment of pathologies in which tissue damage is linked to oxidative stress. Moreover, MSCs appeared to efficiently manage oxidative stress and to be more resistant to oxidative insult than normal somatic cells, making them an interesting and testable model for the role of oxidative stress in the aging process. In addition, aging is accompanied by a progressive decline in stem cell function, resulting in less effective tissue homeostasis and repair. Also, there is an obvious link between intracellular reactive oxygen species levels and cellular senescence. To date, few studies have investigated the promotion of aging by oxidative stress on human MSCs, and the mechanism by which oxidative stress induce stem cell aging is poorly understood. In this context, the aim of this review is to gain insight the current knowledge about the molecular mechanisms of aging-induced oxidative stress in human MSCs.

  12. Physiological Mechanism of Enhancing Salt Stress Tolerance of Perennial Ryegrass by 24-Epibrassinolide

    Directory of Open Access Journals (Sweden)

    Wenli Wu

    2017-06-01

    Full Text Available Brassinosteroids (BR regulate plant tolerance to salt stress but the mechanisms underlying are not fully understood. This study was to investigate physiological mechanisms of 24-epibrassinolide (EBR's impact on salt stress tolerance in perennial ryegrass (Lolium perenne L. The grass seedlings were treated with EBR at 0, 10, and 100 nM, and subjected to salt stress (250 mM NaCl. The grass irrigated with regular water without EBR served as the control. Salt stress increased leaf electrolyte leakage (EL, malondialdehyde (MDA, and reduced photosynthetic rate (Pn. Exogenous EBR reduced EL and MDA, increased Pn, chlorophyll content, and stomatal conductance (gs. The EBR applications also alleviated decline of superoxide dismutase (SOD and catalase (CAT and ascorbate peroxidase (APX activity when compared to salt treatment alone. Salt stress increased leaf abscisic acid (ABA and gibberellin A4 (GA4 content but reduced indole-3-acetic acid (IAA, zeatin riboside (ZR, isopentenyl adenosine (iPA, and salicylic acid (SA. Exogenous EBR at 10 nm and 100 nM increased ABA, and iPA content under salt stress. The EBR treatment at 100 nM also increased leaf IAA, ZR, JA, and SA. In addition, EBR treatments increased leaf proline and ions (K+, Mg2+, and Ca2+ content, and reduced Na+/K+ in leaf tissues. The results of this study suggest that EBR treatment may improve salt stress tolerance by increasing the level of selected hormones and antioxidant enzyme (SOD and CAT activity, promoting accumulation of proline and ions (K+, Ca2+, and Mg2+ in perennial ryegrass.

  13. Proteomics study reveals the molecular mechanisms underlying water stress tolerance induced by Piriformospora indica in barley.

    Science.gov (United States)

    Ghabooli, Mehdi; Khatabi, Behnam; Ahmadi, Farajolah Shahriary; Sepehri, Mozhgan; Mirzaei, Mehdi; Amirkhani, Ardeshir; Jorrín-Novo, Jesús V; Salekdeh, Ghasem Hosseini

    2013-12-06

    Piriformospora indica is a mutualistic root endophytic fungus, which transfers several benefits to hosts including enhance plant growth and increase yield under both normal and stress conditions. It has been shown that P. indica root-colonization enhances water stress tolerance based on general and non-specific plant-species mechanism. To better understand the molecular mechanism of P. indica-mediated drought stress tolerance, we designed a set of comparative experiments to study the impact of P. indica on barely plants cultivar "Golden Promise" grown under different drought levels [Filed capacity (F.C.) and 25% F.C.]. P. indica enhanced root and shoot biomass of colonized plants under both well-watered and water-deficit conditions. Proteome analysis of P. indica-colonized barley leaves under well-treated and water-deficit conditions resulted in detection of 726 reproducibly protein spots. Mass spectrometry analysis resulted in the identification of 45 differentially accumulated proteins involved in photosynthesis, reactive oxygen scavenging, metabolisms, signal transduction, and plant defense responses. Interestingly, P. indica increased the level of proteins involved in photosynthesis, antioxidative defense system and energy transport. We propose that P. indica-mediated drought stress tolerance in barely is through photosynthesis stimulation, energy releasing and enhanced antioxidative capacity in colonized plants. Plant mutualistic symbionts offer long-term abiotic stress tolerance through the host adaptation to environmental stress. There have been a few published proteomic studies of plant symbionts to drought, and this is thought to be the first proteomic analysis, demonstrating the impact of endophyte on barley plant under drought stress. For some of identified proteins like TCTP and PCNA, a connection to physiological function in plants is novel, and can be the best candidates for sources of drought tolerance in future studies. © 2013.

  14. Oxytocin and Stress-related Disorders: Neurobiological Mechanisms and Treatment Opportunities

    Science.gov (United States)

    Sippel, Lauren M.; Allington, Casey E.; Pietrzak, Robert H.; Harpaz-Rotem, Ilan; Mayes, Linda C.; Olff, Miranda

    2017-01-01

    Novel pharmacotherapies that improve outcomes for individuals with stress-related psychiatric disorders are needed. The neurohormone oxytocin (OT) is a promising candidate given its influence on the social–emotional brain. In this review, we present an overview of evidence supporting OT’s utility for treating major depressive disorder and posttraumatic stress disorder. We first discuss endogenous OT, which research suggests is not yet a reliable biomarker of stress-related disorders. Second, we review effects of intranasal (IN) OT on processes relevant to stress-related disorders in healthy populations (anhedonia, reward processing, psychosocial stress reactivity, fear/anxiety, and social behavior) and their neurobiological mechanisms (e.g., the salience network and hypothalamic–pituitary–adrenal axis). Third, we present the sparse but promising findings from clinical populations, followed by discussion of critical moderating variables to consider in the service of maximizing the therapeutic potential of OT (e.g., patient sex and child maltreatment). We also identify heterogeneous findings and limitations of existing research, including reliance on single-dose studies in psychiatrically healthy samples and unanswered questions regarding the effectiveness of IN drug delivery and dosing schedules. Well-controlled multidose studies including women and measures of potentially moderating variables are sorely needed and would inform our understanding of the utility of OT for preventing and treating stress-related psychiatric disorders. PMID:28649672

  15. Influence of solder joint length to the mechanical aspect during the thermal stress analysis

    Science.gov (United States)

    Tan, J. S.; Khor, C. Y.; Rahim, Wan Mohd Faizal Wan Abd; Ishak, Muhammad Ikman; Rosli, M. U.; Jamalludin, Mohd Riduan; Zakaria, M. S.; Nawi, M. A. M.; Aziz, M. S. Abdul; Ani, F. Che

    2017-09-01

    Solder joint is an important interconnector in surface mount technology (SMT) assembly process. The real time stress, strain and displacement of the solder joint is difficult to observe and assess the experiment. To tackle these problems, simulation analysis was employed to study the von Mises stress, strain and displacement in the thermal stress analysis by using Finite element based software. In this study, a model of leadless electronic package was considered. The thermal stress analysis was performed to investigate the effect of the solder length to those mechanical aspects. The simulation results revealed that solder length gives significant effect to the maximum von Mises stress to the solder joint. Besides, changes in solder length also influence the displacement of the solder joint in the thermal environment. The increment of the solder length significantly reduces the von Mises stress and strain on the solder joint. Thus, the understanding of the physical parameter for solder joint is important for engineer prior to designing the solder joint of the electronic component.

  16. Lung stress and strain calculations in mechanically ventilated patients in the intensive care unit.

    Science.gov (United States)

    Blankman, P; Hasan, D; Bikker, I G; Gommers, D

    2016-01-01

    Stress and strain are parameters to describe respiratory mechanics during mechanical ventilation. Calculations of stress require invasive and difficult to perform esophageal pressure measurements. The hypothesis of the present study was: Can lung stress be reliably calculated based on non-invasive lung volume measurements, during a decremental Positive end-expiratory pressure (PEEP) trial in mechanically ventilated patients with different diseases? Data of 26 pressure-controlled ventilated patients admitted to the ICU with different lung conditions were retrospectively analyzed: 11 coronary artery bypass graft (CABG), 9 neurology, and 6 lung disorders. During a decremental PEEP trial (from 15 to 0 cmH2 O in three steps) end-expiratory lung volume (EELV) measurements were performed at each PEEP step, without interruption of mechanical ventilation. Strain, specific elastance, and stress were calculated for each PEEP level. Elastance was calculated as delta PEEP divided by delta PEEP volume, whereas specific elastance is elastance times the FRC. Stress was calculated as specific elastance times the strain. Global strain was divided into dynamic (tidal volume) and static (PEEP) strain. Strain calculations based on FRC showed mainly changes in static component, whereas calculations based on EELV showed changes in both the static and dynamic component of strain. Stress calculated from EELV measurements was 24.0 ± 2.7 and 13.1 ± 3.8 cmH2 O in the lung disorder group at 15 and 5 cmH2 O PEEP. For the normal lungs, the stress values were 19.2 ± 3.2 and 10.9 ± 3.3 cmH2 O, respectively. These values are comparable to earlier publications. Specific elastance calculations were comparable in patients with neurologic and lung disorders, and lower in the CABG group due to recruitment in this latter group. Stress and strain can reliably be calculated at the bedside based on non-invasive EELV measurements during a decremental PEEP trial in patients with different diseases.

  17. Comparing maximum rate and sustainability of pacing by mechanical vs. electrical stimulation in the Langendorff-perfused rabbit heart.

    Science.gov (United States)

    Quinn, T Alexander; Kohl, Peter

    2016-12-01

    Mechanical stimulation (MS) represents a readily available, non-invasive means of pacing the asystolic or bradycardic heart in patients, but benefits of MS at higher heart rates are unclear. Our aim was to assess the maximum rate and sustainability of excitation by MS vs. electrical stimulation (ES) in the isolated heart under normal physiological conditions. Trains of local MS or ES at rates exceeding intrinsic sinus rhythm (overdrive pacing; lowest pacing rates 2.5±0.5 Hz) were applied to the same mid-left ventricular free-wall site on the epicardium of Langendorff-perfused rabbit hearts. Stimulation rates were progressively increased, with a recovery period of normal sinus rhythm between each stimulation period. Trains of MS caused repeated focal ventricular excitation from the site of stimulation. The maximum rate at which MS achieved 1:1 capture was lower than during ES (4.2±0.2 vs. 5.9±0.2 Hz, respectively). At all overdrive pacing rates for which repetitive MS was possible, 1:1 capture was reversibly lost after a finite number of cycles, even though same-site capture by ES remained possible. The number of MS cycles until loss of capture decreased with rising stimulation rate. If interspersed with ES, the number of MS to failure of capture was lower than for MS only. In this study, we demonstrate that the maximum pacing rate at which MS can be sustained is lower than that for same-site ES in isolated heart, and that, in contrast to ES, the sustainability of successful 1:1 capture by MS is limited. The mechanism(s) of differences in MS vs. ES pacing ability, potentially important for emergency heart rhythm management, are currently unknown, thus warranting further investigation. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Cardiology.

  18. Understanding lithospheric stresses: systematic analysis of controlling mechanisms with applications to the African Plate

    Science.gov (United States)

    Medvedev, Sergei

    2016-10-01

    Many mechanisms control the state of stress within Earth plates. First-order well-known mechanisms include stresses induced by lateral variations of lithospheric density structure, sublithospheric tractions, ridge push and subduction pull. In this study, we attempt to quantify the influence of these mechanisms to understand the origin of stresses in the lithosphere, choosing the African plate (TAP) as an example. A finite-element based suite, Proshell, was developed to combine several data sets, to estimate the gravitational potential energy (GPE) of the lithosphere and to calculate stresses acting on the real (non-planar) geometry of TAP. We introduce several quantitative parameters to measure the degree of fit between the model and observations. Our modelling strategy involves nine series of numerical experiments. We start with the simplest possible model and then, step by step, build it up to be a more physically realistic model, all the while discussing the influence of each additional component. The starting (oversimplified) model series (1) is based on the CRUST2 data set for the crust and a half-space-cooling approximation of the lithospheric mantle. We then describe models (series 2-5) that account for lithospheric mantle density heterogeneities to build a more reliable GPE model. The consecutive series involve basal traction from the convective mantle (series A, C) and the rheological heterogeneity of the TAP via variations in its effective elastic thickness (series B, C). The model quality reflects the increase in complexity between series with an improving match to observed stress regimes and directions. The most complex model (series D) also accounts for the bending stresses in the elastic lithosphere and achieves a remarkably good fit to observations. All of our experiments were based on the iteration of controlling parameters in order to achieve the best fit between modelled and observed stresses, always considering physically feasible values. This

  19. The Stress and Vascular Catastrophes in Newborn Rats: Mechanisms Preceding and Accompanying the Brain Hemorrhages.

    Science.gov (United States)

    Semyachkina-Glushkovskaya, Oxana; Borisova, Ekaterina; Abakumov, Maxim; Gorin, Dmitry; Avramov, Latchezar; Fedosov, Ivan; Namykin, Anton; Abdurashitov, Arkady; Serov, Alexander; Pavlov, Alexey; Zinchenko, Ekaterina; Lychagov, Vlad; Navolokin, Nikita; Shirokov, Alexander; Maslyakova, Galina; Zhu, Dan; Luo, Qingming; Chekhonin, Vladimir; Tuchin, Valery; Kurths, Jürgen

    2016-01-01

    In this study, we analyzed the time-depended scenario of stress response cascade preceding and accompanying brain hemorrhages in newborn rats using an interdisciplinary approach based on: a morphological analysis of brain tissues, coherent-domain optical technologies for visualization of the cerebral blood flow, monitoring of the cerebral oxygenation and the deformability of red blood cells (RBCs). Using a model of stress-induced brain hemorrhages (sound stress, 120 dB, 370 Hz), we studied changes in neonatal brain 2, 4, 6, 8 h after stress (the pre-hemorrhage, latent period) and 24 h after stress (the post-hemorrhage period). We found that latent period of brain hemorrhages is accompanied by gradual pathological changes in systemic, metabolic, and cellular levels of stress. The incidence of brain hemorrhages is characterized by a progression of these changes and the irreversible cell death in the brain areas involved in higher mental functions. These processes are realized via a time-depended reduction of cerebral venous blood flow and oxygenation that was accompanied by an increase in RBCs deformability. The significant depletion of the molecular layer of the prefrontal cortex and the pyramidal neurons, which are crucial for associative learning and attention, is developed as a consequence of homeostasis imbalance. Thus, stress-induced processes preceding and accompanying brain hemorrhages in neonatal period contribute to serious injuries of the brain blood circulation, cerebral metabolic activity and structural elements of cognitive function. These results are an informative platform for further studies of mechanisms underlying stress-induced brain hemorrhages during the first days of life that will improve the future generation's health.

  20. Concept of Sustained Ordering and an ATP-related Mechanism of Life’s Origin

    Directory of Open Access Journals (Sweden)

    Erik M. Galimov

    2009-05-01

    Full Text Available This paper shows that the steadystate of a system of conjugated reactions, which are characterized by disproportionation of entropy and proceed in the domain of linear interactions, is an attractor of ordering. Such systems are primed to produce ordering, and life is a specific manifestation of the sustained ordering inherent to the chemistry of carbon. The adenosine triphospate (ATP molecule has properties which makes ATP hydrolysis to be most appropriate to form such a system in primitive world. Hence, ATP is suggested to play a key role in prebiological evolution. Principles of the origin and evolution of life following from the concept of ordering are stated.

  1. The effects of mechanical stress and spectral shading on the growth and allocation of ten genotypes of a stoloniferous plant

    NARCIS (Netherlands)

    Liu, Yun; Schieving, F.; Stuefer, J.F.; Anten, N.P.R.

    2007-01-01

    † Background and Aims Because plants protect each other from wind, stand density affects both the light climate and the amount of mechanical stress experienced by plants. But the potential interactive effects of mechanical stress and canopy shading on plant growth have rarely been investigated and

  2. Mechanical stress downregulates MHC class I expression on human cancer cell membrane.

    Directory of Open Access Journals (Sweden)

    Rosanna La Rocca

    Full Text Available In our body, cells are continuously exposed to physical forces that can regulate different cell functions such as cell proliferation, differentiation and death. In this work, we employed two different strategies to mechanically stress cancer cells. The cancer and healthy cell populations were treated either with mechanical stress delivered by a micropump (fabricated by deep X-ray nanolithography or by ultrasound wave stimuli. A specific down-regulation of Major Histocompatibility Complex (MHC class I molecules expression on cancer cell membrane compared to different kinds of healthy cells (fibroblasts, macrophages, dendritic and lymphocyte cells was observed, stimulating the cells with forces in the range of nano-newton, and pressures between 1 and 10 bar (1 bar = 100.000 Pascal, depending on the devices used. Moreover, Raman spectroscopy analysis, after mechanical treatment, in the range between 700-1800 cm(-1, indicated a relative concentration variation of MHC class I. PCA analysis was also performed to distinguish control and stressed cells within different cell lines. These mechanical induced phenotypic changes increase the tumor immunogenicity, as revealed by the related increased susceptibility to Natural Killer (NK cells cytotoxic recognition.

  3. Mechanical Stress Downregulates MHC Class I Expression on Human Cancer Cell Membrane

    KAUST Repository

    La Rocca, Rosanna

    2014-12-26

    In our body, cells are continuously exposed to physical forces that can regulate different cell functions such as cell proliferation, differentiation and death. In this work, we employed two different strategies to mechanically stress cancer cells. The cancer and healthy cell populations were treated either with mechanical stress delivered by a micropump (fabricated by deep X-ray nanolithography) or by ultrasound wave stimuli. A specific down-regulation of Major Histocompatibility Complex (MHC) class I molecules expression on cancer cell membrane compared to different kinds of healthy cells (fibroblasts, macrophages, dendritic and lymphocyte cells) was observed, stimulating the cells with forces in the range of nano-newton, and pressures between 1 and 10 bar (1 bar = 100.000 Pascal), depending on the devices used. Moreover, Raman spectroscopy analysis, after mechanical treatment, in the range between 700–1800 cm−1, indicated a relative concentration variation of MHC class I. PCA analysis was also performed to distinguish control and stressed cells within different cell lines. These mechanical induced phenotypic changes increase the tumor immunogenicity, as revealed by the related increased susceptibility to Natural Killer (NK) cells cytotoxic recognition.

  4. Thermo-mechanical stress effect on 1-3 piezocomposite power transducer performance.

    Science.gov (United States)

    Richard, C; Lee, H S; Guyomar, D

    2004-04-01

    This paper deals with the emission performance of 1-3 piezoelectric composite power transducers made with a hard PZT (Navy III) and epoxy resins with a high glass-rubber transition temperature. Following the "dice and fill" technique, various composite transducers with 30 and 50% PZT volume fractions were fabricated with an air backing and no front matching layer with resonance operating frequencies around 500 kHz. The transducers were first evaluated under isothermal conditions, with a low emission duty cycle. Efficiencies as high as 95% were monitored as a function of the instantaneous input power up to a 60 W/cm(2) density. The effect of the polymer matrix mechanical losses and the fabrication conditions is then discussed. For the transducer thermal stability, the case of long duty cycle or continuous emission was considered in a second evaluation. In this case the transducer working temperature and axial radiated pressure were monitored as functions of the input power density up to 40 W/cm(2). It is shown that the transducer efficiency and working temperature were strongly dependent on the type of resin used but also on the PZT material, even for hard PZT compositions. A composite transducer configuration with strongly improved thermal stability was investigated demonstrating a working temperature higher than 90 degrees C and an extended power range (30-40 W/cm(2)). The composite thermal breakdown mechanism was analyzed and the effect of the curing-induced thermo-mechanical stresses on the PZT mechanical losses was considered in relation to the composite working temperature. Measurements of the composite mechanical losses versus the temperature were obtained and related to the variation of the PZT mechanical losses with the stresses due to the composite transducer temperature change. It is found that the thermally induced stress can strongly influence the PZT ceramic mechanical losses and that it can be the reason for a thermal breakdown taking place at a

  5. Mechanism of dynamic reorientation of cortical microtubules due to mechanical stress

    CERN Document Server

    Muratov, Alexander

    2015-01-01

    Directional growth caused by gravitropism and corresponding bending of plant cells has been explored since 19th century, however, many aspects of mechanisms underlying the perception of gravity at the molecular level are still not well known. Perception of gravity in root and shoot gravitropisms is usually attributed to gravisensitive cells, called statocytes, which exploit sedimentation of macroscopic and heavy organelles, amyloplasts, to sense the direction of gravity. Gravity stimulus is then transduced into distal elongation zone, which is several mm far from statocytes, where it causes stretching. It is suggested that gravity stimulus is conveyed by gradients in auxin flux. We propose a theoretical model that may explain how concentration gradients and/or stretching may indirectly affect the global orientation of cortical microtubules, attached to the cell membrane and induce their dynamic reorientation perpendicular to the gradients. In turn, oriented microtubules arrays direct the growth and orientatio...

  6. Sustained release of diclofenac from polymer-containing suppository and the mechanism involved.

    Science.gov (United States)

    Azechi, Y; Ishikawa, K; Mizuno, N; Takahashi, K

    2000-11-01

    Sustained release of diclofenac sodium (DcNa) from suppositories composed of triglycerides and polymer was investigated by dissolution testing through an artificial membrane. DcNa was slowly released from a suppository containing carboxyvinyl polymer (CVP), and the extent of the release decreased with the amount of CVP added. Little effect was noted with the addition of other water-soluble polymers, such as hydroxyethylcellulose (HEC), xanthan gum, and polyvinylalcohol (PVA). When sodium benzoate was used instead of DcNa, a similar result was obtained with the addition of CVP. The result of release rate analysis together with the viscosity and pH in these cases showed that the reduction of solubility and diffusion due to sodium exchange between DcNa and CVP played an important role in the sustained release from the suppository. Also, in comparison with the results when CVP was not used, the plasma concentration profile of diclofenac after the administration of CVP suppository displayed a twofold longer half-life time.

  7. Ischemia in tumors induces early and sustained phosphorylation changes in stress kinase pathways but does not affect global protein levels

    Energy Technology Data Exchange (ETDEWEB)

    Mertins, Philipp; Yang, Feng; Liu, Tao; Mani, DR; Petyuk, Vladislav A.; Gillette, Michael; Clauser, Karl; Qiao, Jana; Gritsenko, Marina A.; Moore, Ronald J.; Levine, Douglas; Townsend, Reid; Erdmann-Gilmore, Petra; Snider, Jacqueline E.; Davies, Sherri; Ruggles, Kelly; Fenyo, David; Kitchens, R. T.; Li, Shunqiang; Olvera, Narcisco; Dao, Fanny; Rodriguez, Henry; Chan, Daniel W.; Liebler, Daniel; White, Forest; Rodland, Karin D.; Mills, Gordon; Smith, Richard D.; Paulovich, Amanda G.; Ellis, Matthew; Carr, Steven A.

    2014-07-01

    Advances in quantitative mass spectrometry (MS)-based proteomics have sparked efforts to characterize the proteomes of tumor samples to provide complementary and unique information inaccessible by genomics. Tumor samples are usually not accrued with proteomic characterization in mind, raising concerns regarding effects of undocumented sample ischemia on protein abundance and phosphosite stoichiometry. Here we report the effects of cold ischemia time on clinical ovarian cancer samples and patient-derived basal and luminal breast cancer xenografts. Tumor tissues were excised and collected prior to vascular ligation, subjected to accurately defined ischemia times up to 60 min, and analyzed by quantitative proteomics and phosphoproteomics using isobaric tags and high-performance, multidimensional LC-MS/MS. No significant changes were detected at the protein level in each tumor type after 60 minutes of ischemia, and the majority of the >25,000 phosphosites detected were also stable. However, large, reproducible increases and decreases in protein phosphorylation at specific sites were observed in up to 24% of the phosphoproteome starting as early as 5 minutes post-excision. Early and sustained activation of stress response, transcriptional regulation and cell death pathways were observed in common across tumor types. Tissue-specific changes in phosphosite stability were also observed suggesting idiosyncratic effects of ischemia in particular lineages. Our study provides insights into the information that may be obtained by proteomic characterization of tumor samples after undocumented periods of ischemia, and suggests caution especially in interpreting activation of stress pathways in such samples as they may reflect sample handling rather than tumor physiology.

  8. Sugarcane Water Stress Tolerance Mechanisms and Its Implications on Developing Biotechnology Solutions

    Directory of Open Access Journals (Sweden)

    Thais H. S. Ferreira

    2017-06-01

    Full Text Available Sugarcane is a unique crop with the ability to accumulate high levels of sugar and is a commercially viable source of biomass for bioelectricity and second-generation bioethanol. Water deficit is the single largest abiotic stress affecting sugarcane productivity and the development of water use efficient and drought tolerant cultivars is an imperative for all major sugarcane producing countries. This review summarizes the physiological and molecular studies on water deficit stress in sugarcane, with the aim to help formulate more effective research strategies for advancing our knowledge on genes and mechanisms underpinning plant response to water stress. We also overview transgenic studies in sugarcane, with an emphasis on the potential strategies to develop superior sugarcane varieties that improve crop productivity in drought-prone environments.

  9. [Central and peripheral mu-opioid systems in the mechanisms of emotional stress].

    Science.gov (United States)

    Sudakov, S K; Bashkatova, V G; Kolpakov, A A; Umriukhin, A E

    2011-01-01

    The aim of the work was to study effect of peripheral administration of mu-opioid receptor ligands unable to penetrate through the hematoencephalic barrier on the measures of emotionality in rats and on the release of beta-endorphins from nerve endings of the anterior cingulate cortex during emotional stress. The mu-opioid receptor agonist loperimide mostly acted as an anxiolytic whereas the receptor antagonist methylnaloxon showed depressive activity. Lifetime microdialysis and subsequent immunoenzyme assay demonstrated that intraventricular infusion of loperamide and methylnaloxon decreased and increased respectively the surge of beta-endorphin into the intercellular space. Immobilization-induced emotional stress insignificantly increased the beta-endorphin level in the cingulate cortex. Peripheral administration of loperamide but not methylnaloxon markedly increased the release of the neuropeptide during stress. These findings confirm the hypothesis of the authors about reciprocal interaction of central and peripheral components of the endogenous opioid system and explain the mechanism of antistress action of loperamide.

  10. Formulation of Deformation Stress Fields and Constitutive Equations in Rational Mechanics

    CERN Document Server

    Jianhua, Xiao

    2010-01-01

    In continuum mechanics, stress concept plays an essential role. For complicated materials, different stress concepts are used with ambiguity or different understanding. Geometrically, a material element is expressed by a closed region with arbitral shape. The internal region is acted by distance dependent force (internal body force), while the surface is acted by surface force. Further more, the element as a whole is in a physical background (exterior region) which is determined by the continuum where the element is embedded (external body force). Physically, the total energy can be additively decomposed as three parts: internal region energy, surface energy, and the background energy. However, as forces, they cannot be added directly. After formulating the general forms of physical fields, the deformation tensor is introduced to formulate the force variations caused by deformation. As the force variation is expressed by the deformation tensor, the deformation stress concept is well formulated. Furthermore, a...

  11. A mechanical property and stress corrosion evaluation of 431 stainless steel alloy

    Science.gov (United States)

    Montano, J. W.

    1973-01-01

    The mechanical properties of type 431 stainless steel in two conditions: annealed bar and hardened and tempered bar are presented. Test specimens, manufactured from approximately 1.0 inch (2.54 cm) diameter bar stock, were tested at temperatures of 80 F (+26.7 C), 0 F (-17.8 C), -100 F (-73 C), and -200 F (-129 C). The test data indicated excellent tensile strength, notched/unnotched tensile ratio, ductility, shear, and impact properties at all testing temperatures. Results of the alternate immersion stress corrosion tests on stressed and unstressed longitudinal tensile specimens 0.1250 inch (0.3175 cm) diameter and transverse C-ring specimens, machined from 1.0 inch (2.54 cm) diameter bar stock, indicated that the material is not susceptible to stress corrosion cracking when tested in a 3.5 percent NaCl solution for 180 days.

  12. Embryonic oxidative stress as a mechanism of teratogenesis with special emphasis on diabetic embryopathy.

    Science.gov (United States)

    Ornoy, Asher

    2007-07-01

    Reactive oxygen species (ROS) are involved in the etiology of numerous diseases including cardio-vascular diseases and diabetes mellitus. There is evidence that several teratogens affect the developing embryo by increasing its oxidative stress and, because of its relatively weak antioxidant defense, especially at the early stages of organogenesis, result in severe embryonic damage. This mechanism seems to operate in diabetes-induced embryonic damage as well as in the mechanism of teratogenicity caused by ionizing radiation, hypoxia, alcohol and cocaine use and cigarette smoking. We studied the role of oxidative stress in diabetic induced embryopathy, both in vivo and in vitro. Under diabetic condition there was a significant decrease in the activity of endogenous antioxidant enzymes and of vitamins C and E in the embryos and their yolk sacs. The lowest activity was observed in the malformed experimental embryos when compared to experimental embryos without anomalies. Similar results were obtained in the Cohen diabetic rats, where the diabetic prone (CDs) rats were unable to increase their antioxidant enzyme activity in spite of the diabetes. Studies performed by other investigators show similar results. Human and animal studies show that the main mechanism of fetal damage induced by high levels of ionizing irradiation, cocaine and alcohol abuse, hypoxia and cigarette smoking is also by increased embryonic oxidative stress. Similarly, several drugs exert their teratogenic activity via embryonic oxidative stress. Abnormal placentation may also cause enhanced placental oxidative stress, resulting in embryonic death, preeclampsia or congenital anomalies. Inability of the developing embryo to cope with that stress may result in embryonic death and/or congenital anomalies. Animal studies also show that a variety of antioxidants are effective in decreasing the damaging effects of heightened oxidative stress induced by teratogens. Effective antioxidants, which might also

  13. How stress and temperature conditions affect rock-fluid chemistry and mechanical deformation

    Directory of Open Access Journals (Sweden)

    Anders eNermoen

    2016-02-01

    Full Text Available We report the results from a series of chalk flow-through-compaction experiments performed at three effective stresses (0.5 MPa, 3.5 MPa and 12.3 MPa and two temperatures (92℃ and and 130℃. The results show that both stress and temperature are important to both chemical alteration and mechanical deformation. The experiments were conducted on cores drilled from the same block of outcrop chalks from the Obourg quarry within the Saint Vast formation (Mons, Belgium. The pore pressure was kept at 0.7 MPa for all experiments with a continuous flow of 0.219 M MgCl2 brine at a constant flow rate; 1 original pore volume (PV per day. The experiments have been performed in tri-axial cells with independent control of the external stress (hydraulic pressure in the confining oil, pore pressure, temperature, and the injected flow rate. Each experiment consists of two phases; a loading phase where stress-strain dependencies are investigated (approx. 2 days, and a creep phase that lasts for more than 150-160 days. During creep, the axial deformation was logged, and the effluent samples were collected for ion chromatography analyses. Any difference between the injected and produced water chemistry gives insight into the rock-fluid interactions that occur during flow through of the core. The observed effluent concentration shows a reduction in Mg2+, while the Ca2+ concentration is increased. This, together with SEM-EDS analysis, indicates that magnesium-bearing mineral phases are precipitated leading to dissolution of calcite, an observation . This is in-line with other flow-through experiments reported earlier. The observed dissolution and precipitation are sensitive to the effective stress and test temperature. Typically. H, higher stress and temperature lead to increased concentration differences of Mg2+ and Ca2+ concentration changes.. The observed strain can be partitioned additively into a mechanical and chemical driven component.

  14. Mechanisms of stress, energy homeostasis and insulin resistance in European adolescents--the HELENA study.

    Science.gov (United States)

    Huybrechts, I; De Vriendt, T; Breidenassel, C; Rogiers, J; Vanaelst, B; Cuenca-García, M; Moreno, L A; González-Gross, M; Roccaldo, R; Kafatos, A; Clays, E; Bueno, G; Beghin, L; Sjöstrom, M; Manios, Y; Molnár, D; Pisa, P T; De Henauw, S

    2014-10-01

    Stress is hypothesized to facilitate the development of obesity, whose the foundations are already set during childhood and adolescence. We investigated the relationship between the stress-system, selected mechanisms of energy homeostasis and insulin resistance (IR) in a sample of European adolescents. Within HELENA-CSS, 723 adolescents (12.5-17.5 years) from 10 European cities provided all the necessary data for this study. Fasting blood samples were collected for cortisol, leptin, insulin and glucose analysis. HOMA-IR was calculated from insulin and glucose concentrations. Adolescents' body fat (BF) %, age and duration of exclusive breastfeeding were assessed. For boys and girls separately, the relationship of cortisol with leptin, insulin, glucose and HOMA-IR was examined by computing Pearson correlation coefficients and Hierarchical Linear Models (HLMs), with 'city' as cluster unit, adjusting for age, BF% and duration of exclusive breastfeeding. In boys, Pearson correlation coefficients illustrated positive correlations of cortisol with insulin (r = 0.144; p = 0.013), glucose (r = 0.315; p adolescents' age, BF% and duration of exclusive breastfeeding after computing HLMs. This study suggests that the stress-system is positively related to mechanisms of energy homeostasis and IR in European adolescents, and reveals a potential small gender difference in this relationship. The hypothesis that stress might facilitate the development of obesity during adolescence is supported. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. An Impact of Mechanical Stress in Coal Briquettes on Sorption of Carbon Dioxide

    Science.gov (United States)

    Wierzbicki, Mirosław

    2017-09-01

    The presence of gases (methane or carbon dioxide) in hard coal is connected with numerous threats for miners employed in underground mining facilities. When analyzing the coal-methane system, it is necessary to determine the relationship between pressure and gas sorption. Such a relationship should be determined under conditions similar to the natural ones - when it comes to both temperature and pressure. The present paper discusses the results of research conducted with the use of coal briquettes under the state of mechanical stress. Carbon dioxide sorption isotherms were determined for different values of stress affecting the coal material. For five coal samples collected in different mines of the Upper Silesian Coal Basin, Langmuir's sorption isotherms were determined. The results point to significant impact that mechanical stress has upon the sorption process. It is about 1 percent of the value obtained for coal not subjected to stress per 1 MPa. The research results can also prove useful when analyzing hard coal seams from the perspective of their carbon dioxide sequestration abilities.

  16. The stress corrosion resistance and the cryogenic temperature mechanical properties of annealed Nitronic 60 bar material

    Science.gov (United States)

    Montano, J. W. L.

    1977-01-01

    Ambient and cryogenic temperature mechanical properties and the ambient temperature stress corrosion properties of annealed, straightened, and centerless ground Nitronic 60 stainless steel alloy bar material are presented. The mechanical properties of longitudinal specimens were evaluated at test temperatures from ambient to liquid hydrogen. The tensile test data indicated increasing strength with decreasing temperature to -196 C. Below liquid nitrogen temperature the smooth tensile and notched tensile strengths decreased slightly while the elongation and reduction of area decreased drastically. The Charpy V-notched impact energy decreased steadily with decreasing test temperature. Stress corrosion tests were performed on longitudinal tensile specimens and transverse C-ring specimens exposed to: alternate immersion in a 3.5% NaCl bath; humidity cabinet; and a 5% salt spray atmosphere. The longitudinal tensile specimens experienced no corrosive attack. Approximately 3/4 of the transverse C-rings exposed to alternate immersion and to salt spray experienced a pitting attack on the top and bottom ends. Additional stress corrosion tests were performed on transverse tensile specimens. No failures occurred in the 90% stressed specimens exposed for 90 days in the alternate immersion and salt spray environments

  17. Blood markers of oxidative stress predict weaning failure from mechanical ventilation

    Science.gov (United States)

    Verona, Cléber; Hackenhaar, Fernanda S; Teixeira, Cassiano; Medeiros, Tássia M; Alabarse, Paulo V; Salomon, Tiago B; Shüller, Ártur K; Maccari, Juçara G; Condessa, Robledo Leal; Oliveira, Roselaine P; Rios Vieira, Silvia R; Benfato, Mara S

    2015-01-01

    Patients undergoing mechanical ventilation (MV) often experience respiratory muscle dysfunction, which complicates the weaning process. There is no simple means to predict or diagnose respiratory muscle dysfunction because diagnosis depends on measurements in muscle diaphragmatic fibre. As oxidative stress is a key mechanism contributing to MV-induced respiratory muscle dysfunction, the aim of this study was to determine if differences in blood measures of oxidative stress in patients who had success and failure in a spontaneous breathing trial (SBT) could be used to predict the outcome of MV. This was a prospective analysis of MV-dependent patients (≥72 hrs; n = 34) undergoing a standard weaning protocol. Clinical, laboratory and oxidative stress analyses were performed. Measurements were made on blood samples taken at three time-points: immediately before the trial, 30 min. into the trial in weaning success (WS) patients, or immediately before return to MV in weaning failure (WF) patients, and 6 hrs after the trial. We found that blood measures of oxidative stress distinguished patients who would experience WF from patients who would experience WS. Before SBT, WF patients presented higher oxidative damage in lipids and higher antioxidant levels and decreased nitric oxide concentrations. The observed differences in measures between WF and WS patients persisted throughout and after the weaning trial. In conclusion, WF may be predicted based on higher malondialdehyde, higher vitamin C and lower nitric oxide concentration in plasma. PMID:25854285

  18. Effect of mechanical stress on current-voltage characteristics of thin film polycrystalline diamond Schottky diodes

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, G.; Charlson, E.M.; Charlson, E.J.; Stacy, T.; Meese, J.M. (Department of Electrical and Computer Engineering, University of Missouri, Columbia, Missouri 65211 (United States)); Popovici, G.; Prelas, M. (Department of Nuclear Engineering, University of Missouri, Columbia, Missouri 65211 (United States))

    1993-02-15

    Schottky diodes utilized for mechanical stress effect studies were fabricated using aluminum contacts to polycrystalline diamond thin films grown by a hot-filament-assisted chemical vapor deposition process. Compressive stress was found to have a large effect on the forward biased current-voltage characteristics of the diode, whereas the effect on the reverse biased characteristics was relatively small. This stress effect on the forward biased diamond Schottky diode was attributed to piezojunction and piezoresistance effects that dominated the diode current-voltage characteristics in the small and large bias regions, respectively. At a large constant forward bias current, a good linear relationship between output voltage and applied force was observed for force of less than 10 N, as predicted by the piezoresistance effect. The measured force sensitivity of the diode was as high as 0.75 V/N at 1 mA forward bias. Compared to either silicon or germanium junction diodes and tunnel diodes, polycrystalline diamond Schottky diodes not only are very stress sensitive but also have good linearity. This study shows polycrystalline diamond Schottky diodes have potential as mechanical sensors.

  19. Performance of a TiN-coated monolithic silicon pin-diode array under mechanical stress

    Energy Technology Data Exchange (ETDEWEB)

    VanDevender, B.A., E-mail: brent.vandevender@pnnl.gov [Center for Experimental Nuclear Physics and Astrophysics and Department of Physics, University of Washington, Seattle, WA 98195 (United States); Bodine, L.I.; Myers, A.W.; Amsbaugh, J.F.; Howe, M.A.; Leber, M.L.; Robertson, R.G.H.; Tolich, K.; Van Wechel, T.D.; Wall, B.L. [Center for Experimental Nuclear Physics and Astrophysics and Department of Physics, University of Washington, Seattle, WA 98195 (United States)

    2012-05-01

    The Karlsruhe Tritium Neutrino Experiment (KATRIN) will detect tritium {beta}-decay electrons that pass through its electromagnetic spectrometer with a highly segmented monolithic silicon pin-diode focal-plane detector (FPD). This pin-diode array will be on a single piece of 500-{mu}m-thick silicon, with contact between titanium nitride (TiN)-coated detector pixels and front-end electronics made by spring-loaded pogo pins. The pogo pins will exert a total force of up to 50 N on the detector, deforming it and resulting in mechanical stress up to 50 MPa in the silicon bulk. We have evaluated a prototype pin-diode array with a pogo-pin connection scheme similar to the KATRIN FPD. We find that pogo pins make good electrical contact to TiN and observe no effects on detector resolution or reverse-bias leakage current which can be attributed to mechanical stress.

  20. Synaptic rewiring of stress-sensitive neurons by early-life experience: a mechanism for resilience?

    Science.gov (United States)

    Singh-Taylor, Akanksha; Korosi, Aniko; Molet, Jenny; Gunn, Benjamin G; Baram, Tallie Z

    2015-01-01

    Genes and environment interact to influence cognitive and emotional functions throughout life. Early-life experiences in particular contribute to vulnerability or resilience to a number of emotional and cognitive illnesses in humans. In rodents, early-life experiences directly lead to resilience or vulnerability to stress later in life, and influence the development of cognitive and emotional deficits. The mechanisms for the enduring effects of early-life experiences on cognitive and emotional outcomes are not completely understood. Here, we present emerging information supporting experience-dependent modulation of the number and efficacy of synaptic inputs onto stress-sensitive neurons. This synaptic 'rewiring', in turn, may influence the expression of crucial neuronal genes. The persistent changes in gene expression in resilient versus vulnerable rodent models are likely maintained via epigenetic mechanisms. Thus, early-life experience may generate resilience by altering synaptic input to neurons, which informs them to modulate their epigenetic machinery.

  1. Changes in permeability caused by transient stresses: field observations, experiments, and mechanisms

    Science.gov (United States)

    Manga, Michael; Beresnev, Igor; Brodsky, Emily E.; Elkhoury, Jean E.; Elsworth, Derek; Ingebritsen, Steve E.; Mays, David C.; Wang, Chi-Yuen

    2012-01-01

    Oscillations in stress, such as those created by earthquakes, can increase permeability and fluid mobility in geologic media. In natural systems, strain amplitudes as small as 10–6 can increase discharge in streams and springs, change the water level in wells, and enhance production from petroleum reservoirs. Enhanced permeability typically recovers to prestimulated values over a period of months to years. Mechanisms that can change permeability at such small stresses include unblocking pores, either by breaking up permeability-limiting colloidal deposits or by mobilizing droplets and bubbles trapped in pores by capillary forces. The recovery time over which permeability returns to the prestimulated value is governed by the time to reblock pores, or for geochemical processes to seal pores. Monitoring permeability in geothermal systems where there is abundant seismicity, and the response of flow to local and regional earthquakes, would help test some of the proposed mechanisms and identify controls on permeability and its evolution.

  2. Molecular mechanisms of Saccharomyces cerevisiae stress adaptation and programmed cell death in response to acetic acid

    Directory of Open Access Journals (Sweden)

    Sergio eGiannattasio

    2013-02-01

    Full Text Available Beyond its classical biotechnological applications such as food and beverage production or as a cell factory, the yeast Saccharomyces cerevisiae is a valuable model organism to study fundamental mechanisms of cell response to stressful environmental changes. Acetic acid is a physiological product of yeast fermentation and it is a well-known food preservative due to its antimicrobial action. Acetic acid has recently been shown to cause yeast cell death and aging. Here we shall focus on the molecular mechanisms of S. cerevisiae stress adaptation and programmed cell death in response to acetic acid. We shall elaborate on the intracellular signaling pathways involved in the cross-talk of pro-survival and pro-death pathways underlying the importance of understanding fundamental aspects of yeast cell homeostasis to improve the performance of a given yeast strain in biotechnological applications.

  3. The world's road to water scarcity: shortage and stress in the 20th century and pathways towards sustainability.

    Science.gov (United States)

    Kummu, M; Guillaume, J H A; de Moel, H; Eisner, S; Flörke, M; Porkka, M; Siebert, S; Veldkamp, T I E; Ward, P J

    2016-12-09

    Water scarcity is a rapidly growing concern around the globe, but little is known about how it has developed over time. This study provides a first assessment of continuous sub-national trajectories of blue water consumption, renewable freshwater availability, and water scarcity for the entire 20th century. Water scarcity is analysed using the fundamental concepts of shortage (impacts due to low availability per capita) and stress (impacts due to high consumption relative to availability) which indicate difficulties in satisfying the needs of a population and overuse of resources respectively. While water consumption increased fourfold within the study period, the population under water scarcity increased from 0.24 billion (14% of global population) in the 1900s to 3.8 billion (58%) in the 2000s. Nearly all sub-national trajectories show an increasing trend in water scarcity. The concept of scarcity trajectory archetypes and shapes is introduced to characterize the historical development of water scarcity and suggest measures for alleviating water scarcity and increasing sustainability. Linking the scarcity trajectories to other datasets may help further deepen understanding of how trajectories relate to historical and future drivers, and hence help tackle these evolving challenges.

  4. Approach to Operational Experimental Estimation of Static Stresses of Elements of Mechanical Structures

    Science.gov (United States)

    Sedov, A. V.; Kalinchuk, V. V.; Bocharova, O. V.

    2018-01-01

    The evaluation of static stresses and strength of units and components is a crucial task for increasing reliability in the operation of vehicles and equipment, to prevent emergencies, especially in structures made of metal and composite materials. At the stage of creation and commissioning of structures to control the quality of manufacturing of individual elements and components, diagnostic control methods are widely used. They are acoustic, ultrasonic, X-ray, radiation methods and others. The using of these methods to control the residual life and the degree of static stresses of units and parts during operation is fraught with great difficulties both in methodology and in instrumentation. In this paper, the authors propose an effective approach of operative control of the degree of static stresses of units and parts of mechanical structures which are in working condition, based on recording the changing in the surface wave properties of a system consisting of a sensor and a controlled environment (unit, part). The proposed approach of low-frequency diagnostics of static stresses presupposes a new adaptive-spectral analysis of a surface wave created by external action (impact). It is possible to estimate implicit stresses of structures in the experiment due to this approach.

  5. Introduction of Enhanced Compressive Residual Stress Profiles in Aerospace Components Using Combined Mechanical Surface Treatments

    Science.gov (United States)

    Gopinath, Abhay; Lim, Andre; Nagarajan, Balasubramanian; Cher Wong, Chow; Maiti, Rajarshi; Castagne, Sylvie

    2016-11-01

    Mechanical surface treatments such as Shot Peening (SP) and Deep Cold Rolling (DCR) are being used to introduce Compressive Residual Stress (CRS) at the surface and subsurface layers of aerospace components, respectively. This paper investigates the feasibility of a combined introduction of both the surface and sub-surface compressive residual stress on Ti6Al4V material through a successive application of the two aforementioned processes, one after the other. CRS profiles between individual processes were compared to that of combination of processes to validate the feasibility. It was found out that shot peening introduces surface compressive residual stress into the already deep cold rolled sample, resulting in both surface and sub-surface compressive residual stresses in the material. However the drawback of such a combination would be the increased surface roughness after shot peening a deep cold rolled sample which can be critical especially in compressor components. Hence, a new technology, Vibro-Peening (VP) may be used as an alternative to SP to introduce surface stress at reduced roughness.

  6. Metabolic profiles of flooding-tolerant mechanism in early-stage soybean responding to initial stress.

    Science.gov (United States)

    Wang, Xin; Zhu, Wei; Hashiguchi, Akiko; Nishimura, Minoru; Tian, Jingkui; Komatsu, Setsuko

    2017-08-01

    Metabolomic analysis of flooding-tolerant mutant and abscisic acid-treated soybeans suggests that accumulated fructose might play a role in initial flooding tolerance through regulation of hexokinase and phosphofructokinase. Soybean is sensitive to flooding stress, which markedly reduces plant growth. To explore the mechanism underlying initial-flooding tolerance in soybean, mass spectrometry-based metabolomic analysis was performed using flooding-tolerant mutant and abscisic-acid treated soybeans. Among the commonly-identified metabolites in both flooding-tolerant materials, metabolites involved in carbohydrate and organic acid displayed same profile at initial-flooding stress. Sugar metabolism was highlighted in both flooding-tolerant materials with the decreased and increased accumulation of sucrose and fructose, respectively, compared to flooded soybeans. Gene expression of hexokinase 1 was upregulated in flooded soybean; however, it was downregulated in both flooding-tolerant materials. Metabolites involved in carbohydrate/organic acid and proteins related to glycolysis/tricarboxylic acid cycle were integrated. Increased protein abundance of phosphofructokinase was identified in both flooding-tolerant materials, which was in agreement with its enzyme activity. Furthermore, sugar metabolism was pointed out as the tolerant-responsive process at initial-flooding stress with the integration of metabolomics, proteomics, and transcriptomics. Moreover, application of fructose declined the increased fresh weight of plant induced by flooding stress. These results suggest that fructose might be the critical metabolite through regulation of hexokinase and phosphofructokinase to confer initial-flooding stress in soybean.

  7. The influence of acute stress on attention mechanisms and its electrophysiological correlates

    Directory of Open Access Journals (Sweden)

    Jessica eSänger

    2014-10-01

    Full Text Available For the selection of relevant information out of a continuous stream of information, which is a common definition of attention, two core mechanisms are assumed: a competition-based comparison of the neuronal activity in sensory areas and the top-down modulation of this competition by frontal executive control functions. Those control functions are thought to bias the processing of information towards the intended goals. Acute stress is thought to impair these frontal functions through the release of cortisol.In the present study, subjects had to detect a luminance change of a stimulus and ignore more salient but task irrelevant orientation changes. Before the execution of this task, subjects underwent a socially evaluated cold pressor test (SECPT or a non-stressful control situation. The SECPT revealed reliable stress response with a significant increase of cortisol and alpha-amylase. Stressed subjects showed higher error rates than controls, particularly in conditions which require top-down control processing to bias the less salient target feature against the more salient and spatially separated distracter.By means of the EEG, subjects who got stressed showed a reduced allocation to the relevant luminance change apparent in a modulation of the N1pc. The following N2pc, which reflects a re-allocation of attentional resources, supports the error pattern. There was only an N2pc in conditions, which required to bias the less salient luminance change. Moreover, this N2pc was decreased as a consequence of the induced stress. These results allow the conclusion that acute stress impairs the intention-based attentional allocation and enhances the stimulus-driven selection, leading to a strong distractibility during attentional information selection.

  8. The effects of kratom on restraint-stress-induced analgesia and its mechanisms of action.

    Science.gov (United States)

    Vázquez López, José Luis; Schild, Lorenz; Günther, Thomas; Schulz, Stefan; Neurath, Hartmud; Becker, Axel

    2017-06-09

    Mitragyna speciosa and its extracts are called kratom (dried leaves, extract). They contain several alkaloids with an affinity for different opioid receptors. They are used in traditional medicine for the treatment of different diseases, as a substitute by opiate addicts, and to mitigate opioid withdrawal symptoms. Apart from their medical properties, they are used to enhance physical endurance and as a means of overcoming stress. The aim of this study was to determine the mechanisms underlying the effects of kratom on restraint-stress-induced analgesia which occurs during or following exposure to a stressful or fearful stimulus. To gain further insights into the action of kratom on stress, we conducted experiments using restraint stress as a test system and stress-induced analgesia as a test parameter. Using transgenic mu opioid-receptor (MOR) deficient mice, we studied the involvement of this receptor type. We used nor-binaltorphimine (BNT), an antagonist at kappa opioid receptors (KOR), to study functions of this type of receptor. Membrane potential assay was also employed to measure the intrinsic activity of kratom in comparison to U50,488, a highly selective kappa agonist. Treatment with kratom diminished stress-induced analgesia in wildtype and MOR knockout animals. Pretreatment of MOR deficient mice with BNT resulted in similar effects. In comparison to U50,488, kratom exhibited negligible intrinsic activity at KOR alone. The results suggest that the use of kratom as a pharmacological tool to mitigate withdrawal symptoms is related to its action on KOR. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

  9. Under Stress: Social Coping Mechanisms for Survival among the Working Professionals

    OpenAIRE

    Ms. Coral Barboza; Dr. Babu Thomas

    2016-01-01

    The nature of work of professionals and their family life may very often expose them to high level of stress which has the potential of affecting their productive and earning capacity. Coping strategies have been the subject of many studies and various suggestions have been made regarding the most appropriate way to categorise them in terms of function and efficacy (Amble, 2006; Buys et al., 2010). The goal of the current study was to examine how social coping mechanisms are helpful to employ...

  10. Involvement of epigenetic mechanisms in the development of posttraumatic stress disorder

    Directory of Open Access Journals (Sweden)

    Tomaž Zupanc

    2012-03-01

    victims with no childhood abuse were found. It was suggested that changes in glucocorticoid system are mediated by tissue-specific changes in gene expression. Recent studies suggest that epigenetic mechanisms may play an important role in the interplay between stress exposure and genetic vulnerability. Conclusions: Integrating epigenetics into a model that permits prior experience to have a central role in determining individual differences is also consistent with a developmental perspective of PTSD vulnerability.

  11. EFFECT OF MINDFULLNESS MEDITATION ON STRESS LEVEL AND COPING MECHANISM IN CANCER PATIENTS

    OpenAIRE

    Wahyu Werdani, Yesiana Dwi

    2017-01-01

    Cancer patients have a tendency to experience mental disorders, because the physical changes cause frustration and despair. It impacts on anxiety, depression, and social isolation. The purpose of this study was to analyze the influence of mindfullness meditation to stress levels and coping mechanisms in cancer patients. This study used pre experimental approach with one group pre-test post-test design. Samples were 32 cancer patients with composmentis condition in Indonesian Cancer Foundation...

  12. Mechanical spectroscopy of thermal stress relaxation in aluminium alloys reinforced with short alumina fibres

    Energy Technology Data Exchange (ETDEWEB)

    Carreno-Morelli, E.; Schaller, R. [Ecole Polytechnique Federale, Lausanne (Switzerland). Inst. de Genie Atomique; Urreta, S.E.

    1998-05-01

    The mechanical behaviour under low temperature thermal cycling of aluminium-based composites reinforced with short Al{sub 2}O{sub 3} SAFFIL fibres has been investigated by mechanical spectroscopy (mechanical loss and elastic shear modulus measurements). A mechanical loss maximum has been observed during cooling which originates in the relaxation of thermal stresses at the interfaces due to the differential thermal expansion between matrix and reinforcement. The maximum height increases with the volumetric fibre content. In addition, if the matrix strength is increased by the appropriated choice of alloy and thermal treatment, the maximum diminishes and shifts to lower temperatures. No damage accumulation at the interfaces has been detected during long period thermal cycling in the range 100 to 500 K. A description of the damping behaviour is made in terms of the development of microplastic zones which surround the fibres. (orig.) 9 refs.

  13. Circuit and synaptic mechanisms of repeated stress: Perspectives from differing contexts, duration, and development

    Directory of Open Access Journals (Sweden)

    Kevin G. Bath

    2017-12-01

    Full Text Available The current review is meant to synthesize research presented as part of a symposium at the 2016 Neurobiology of Stress workshop in Irvine California. The focus of the symposium was “Stress and the Synapse: New Concepts and Methods” and featured the work of several junior investigators. The presentations focused on the impact of various forms of stress (altered maternal care, binge alcohol drinking, chronic social defeat, and chronic unpredictable stress on synaptic function, neurodevelopment, and behavioral outcomes. One of the goals of the symposium was to highlight the mechanisms accounting for how the nervous system responds to stress and their impact on outcome measures with converging effects on the development of pathological behavior. Dr. Kevin Bath's presentation focused on the impact of disruptions in early maternal care and its impact on the timing of hippocampus maturation in mice, finding that this form of stress drove accelerated synaptic and behavioral maturation, and contributed to the later emergence of risk for cognitive and emotional disturbance. Dr. Scott Russo highlighted the impact of chronic social defeat stress in adolescent mice on the development and plasticity of reward circuity, with a focus on glutamatergic development in the nucleus accumbens and mesolimbic dopamine system, and the implications of these changes for disruptions in social and hedonic response, key processes disturbed in depressive pathology. Dr. Kristen Pleil described synaptic changes in the bed nuclei of the stria terminalis that underlie the behavioral consequences of allostatic load produced by repeated cycles of alcohol binge drinking and withdrawal. Dr. Eric Wohleb and Dr. Ron Duman provided new data associating decreased mammalian target of rapamycin (mTOR signaling and neurobiological changes in the synapses in response to chronic unpredictable stress, and highlighted the potential for the novel antidepressant ketamine to rescue

  14. Plasticity of the MAPK signaling network in response to mechanical stress.

    Directory of Open Access Journals (Sweden)

    Andrea M Pereira

    Full Text Available Cells display versatile responses to mechanical inputs and recent studies have identified the mitogen-activated protein kinase (MAPK cascades mediating the biological effects observed upon mechanical stimulation. Although, MAPK pathways can act insulated from each other, several mechanisms facilitate the crosstalk between the components of these cascades. Yet, the combinatorial complexity of potential molecular interactions between these elements have prevented the understanding of their concerted functions. To analyze the plasticity of the MAPK signaling network in response to mechanical stress we performed a non-saturating epistatic screen in resting and stretched conditions employing as readout a JNK responsive dJun-FRET biosensor. By knocking down MAPKs, and JNK pathway regulators, singly or in pairs in Drosophila S2R+ cells, we have uncovered unexpected regulatory links between JNK cascade kinases, Rho GTPases, MAPKs and the JNK phosphatase Puc. These relationships have been integrated in a system network model at equilibrium accounting for all experimentally validated interactions. This model allows predicting the global reaction of the network to its modulation in response to mechanical stress. It also highlights its context-dependent sensitivity.

  15. Effects of mechanical stress and vitreous samples in retinal pigment epithelial cells.

    Science.gov (United States)

    Takahashi, Eri; Fukushima, Ayako; Haga, Akira; Inomata, Yasuya; Ito, Yasuhiro; Fukushima, Mikiko; Tanihara, Hidenobu

    2016-02-12

    In rhegmatogenous retinal detachment (RRD), scattered RPE cells from the basement membrane into the vitreous cavity undergo an epithelial mesenchymal transition (EMT) and form the intraocular fibrous membrane in response to vitreous fluid. We investigated whether exposure to vitreous samples was associated with EMT-associated signals and mesenchymal characters. Human vitreous samples were collected from patients with RRD, epiretinal membrane (ERM), or macular hole (MH). We evaluated the effects of vitreous on ARPE-19 cells in suspension cultures using poly 2-hydroxyethyl methacrylate-coated dishes and three-dimensional (3D) Matrigel cultures. We found that exposure to vitreous samples did not induce morphological changes or accelerate wound closure in monolayers. Several samples showed increased phosphorylation of Smad2 and nuclear translocation of nuclear factor-κB. Mechanical stress triggered an elevation of phosphorylation levels in Smad2. In addition, exposure to vitreous fluid increased the phosphorylation of p38 mitogen-activated protein kinase in cell suspension cultures after mechanical stress. Moreover, ARPE-19 cells showed a stellate invasive phenotype in 3D Matrigel cultures with vitreous samples. In this study, we demonstrated that mechanical stress and vitreous were associated with EMT-associated signals and invasive phenotypes in 3D cultures but not in monolayers. These results have important implications for the role of vitreous humor in the induction of EMT and intraocular fibrosis. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Mechanical Stress Results in Immediate Accumulation of Glucosinolates in Fresh-Cut Cabbage

    Directory of Open Access Journals (Sweden)

    Tomaž Požrl

    2015-01-01

    Full Text Available The intensity of mechanical stress and the temperature significantly affect the levels of individual and total glucosinolates in shredded white cabbage (cv. Galaxy. Mild processing (shredding to 2 mm thickness at 8°C resulted in the accumulation of glucosinolates (40% increase in comparison with unshredded cabbage, which was already seen 5 min after the mechanical stress. Severe processing (shredding to 0.5 mm thickness at 20°C, however, resulted in an initial 50% decrease in glucosinolates. The glucosinolates accumulated in all of the cabbage samples 30 min from processing, resulting in higher levels than in unshredded cabbage, except for the severe processing at 20°C where the increase was not sufficient to compensate for the initial loss. Glucobrassicin and neoglucobrassicin were the major glucosinolates identified in the cabbage samples. Mechanical stress resulted in an increase in the relative proportion of glucobrassicin and in a decrease in neoglucobrassicin.

  17. A mechanical property and stress corrosion evaluation of Custom 455 stainless steel alloy

    Science.gov (United States)

    Montano, J. W.

    1972-01-01

    The mechanical and stress corrosion properties are presented of vacuum melted Custom 455 stainless steel alloy bar (1.0-inch diameter) and sheet (0.083-inch thick) material aged at 950 F, 1000 F, and 1050 F. Low temperature mechanical properties were determined at temperatures of 80 F, 0 F, -100 F, and -200 F. For all three aging treatments, the ultimate tensile and 0.2 percent offset yield strengths increased with decreasing test temperatures while the elongation held fairly constant down to -100 F and decreased at -200 F. Reduction in Area decreased moderately with decreasing temperature for the longitudinal round (0.250-inch diameter) specimens. Notched tensile strength and charpy V-notched impact strength decreased with decreasing test temperature. For all three aging treatments, no failures were observed in the unstressed specimens or the specimens stressed to 50, 75, and 100 percent of their yield strengths for 180 days of alternate immersion testing in a 3.5 percent NaCl solution. As indicated by the results of tensile tests performed after alternate immersion testing, the mechanical properties of Custom 455 alloy were not affected by stress or exposure under the conditions of the evaluation.

  18. Mechanisms of autoprotection and the role of stress-proteins in natural defenses, autoprotection, and salutogenesis.

    Science.gov (United States)

    Schaefer, J; Nierhaus, K H; Lohff, B; Peters, T; Schaefer, T; Vos, R

    1998-08-01

    We hypothesize that in all physiotherapeutically oriented procedures of naturotherapy -- such as helio-, climate-, thalasso- or hydrotherapy or certain forms of physical exercise -- the transient expression of stress-proteins (heat-shock proteins, HSPs) is an important element of salutogenesis. These therapeutical procedures all cause a transitory 'disturbance' by an unspecific stressor that leads to functional responses. These functional responses can be trained and thus increase the forces and the capacity for resistance of the organism. The autoprotective mechanisms which we want to deal with in more detail are based on the functions of the heat-shock proteins (HSPs, stress-response proteins, 'chaperones') and represent archaic autoprotective responses. In addition, more complex mechanisms of autoprotection seem to have evolved that may play a role in the natural defenses against disease and which show a hierarchy of various genomically conserved strategies with different time-constants and time windows. This becomes apparent by studying autoprotective responses of the cardiovascular system of warm-blooded animals under ischemic stress. Recent extensive experimental protocols and clinical observations in elucidating the molecular basis of cardiac ischemia show that powerful autoprotective mechanisms are involved in the phenomena of 'hibernation', 'stunning', and 'ischemic preconditioning'. The system of the heat-shock proteins may therefore be regarded as a basic model for the principle of autoprotection and salutogenesis.

  19. Degradation mechanism of AlGaN/GaN HEMTs during high temperature operation stress

    Science.gov (United States)

    Chen, Y. Q.; Liao, X. Y.; Zeng, C.; Peng, C.; Liu, Y.; Li, R. G.; En, Y. F.; Huang, Y.

    2018-01-01

    The degradation behavior and its physical mechanism of AlGaN/GaN high electron mobility transistors (HEMTs) during high temperature operation (HTO) stress were investigated in this paper. The results show that the gate leakage current of AlGaN/GaN HEMTs after 1000 h HTO stress is two orders of magnitude larger than that of the fresh ones. The maximum transconductance of the AlGaN/GaN HEMTs obviously decreases from 0.31 to 0.21 s after 1000 h HTO stress, which indicates the gate degraded seriously. The mechanism for the gate degradation could be attributed to the Au diffusion that degrades the barrier. Moreover, the output characteristics are also deteriorated seriously, and the maximum variation of drain-to-source current is up to 119 mA under the conditions of gate-to-source voltage of 0 V and drain-to-source voltage of 5 V. The reason for the deterioration of output characteristics could be attributed to two mechanisms of gate degradation and structural damage such as pit-like, crack-like damages. The results may be useful in the design and application of AlGaN/GaN HEMTs.

  20. Effects of mechanical stress and vitreous samples in retinal pigment epithelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Eri, E-mail: eritakahashi@fc.kuh.kumamoto-u.ac.jp; Fukushima, Ayako; Haga, Akira; Inomata, Yasuya; Ito, Yasuhiro; Fukushima, Mikiko; Tanihara, Hidenobu

    2016-02-12

    In rhegmatogenous retinal detachment (RRD), scattered RPE cells from the basement membrane into the vitreous cavity undergo an epithelial mesenchymal transition (EMT) and form the intraocular fibrous membrane in response to vitreous fluid. We investigated whether exposure to vitreous samples was associated with EMT-associated signals and mesenchymal characters. Human vitreous samples were collected from patients with RRD, epiretinal membrane (ERM), or macular hole (MH). We evaluated the effects of vitreous on ARPE-19 cells in suspension cultures using poly 2-hydroxyethyl methacrylate-coated dishes and three-dimensional (3D) Matrigel cultures. We found that exposure to vitreous samples did not induce morphological changes or accelerate wound closure in monolayers. Several samples showed increased phosphorylation of Smad2 and nuclear translocation of nuclear factor-κB. Mechanical stress triggered an elevation of phosphorylation levels in Smad2. In addition, exposure to vitreous fluid increased the phosphorylation of p38 mitogen-activated protein kinase in cell suspension cultures after mechanical stress. Moreover, ARPE-19 cells showed a stellate invasive phenotype in 3D Matrigel cultures with vitreous samples. In this study, we demonstrated that mechanical stress and vitreous were associated with EMT-associated signals and invasive phenotypes in 3D cultures but not in monolayers. These results have important implications for the role of vitreous humor in the induction of EMT and intraocular fibrosis.

  1. Micro-environmental mechanical stress controls tumor spheroid size and morphology by suppressing proliferation and inducing apoptosis in cancer cells.

    Directory of Open Access Journals (Sweden)

    Gang Cheng

    Full Text Available Compressive mechanical stress produced during growth in a confining matrix limits the size of tumor spheroids, but little is known about the dynamics of stress accumulation, how the stress affects cancer cell phenotype, or the molecular pathways involved.We co-embedded single cancer cells with fluorescent micro-beads in agarose gels and, using confocal microscopy, recorded the 3D distribution of micro-beads surrounding growing spheroids. The change in micro-bead density was then converted to strain in the gel, from which we estimated the spatial distribution of compressive stress around the spheroids. We found a strong correlation between the peri-spheroid solid stress distribution and spheroid shape, a result of the suppression of cell proliferation and induction of apoptotic cell death in regions of high mechanical stress. By compressing spheroids consisting of cancer cells overexpressing anti-apoptotic genes, we demonstrate that mechanical stress-induced apoptosis occurs via the mitochondrial pathway.Our results provide detailed, quantitative insight into the role of micro-environmental mechanical stress in tumor spheroid growth dynamics, and suggest how tumors grow in confined locations where the level of solid stress becomes high. An important implication is that apoptosis via the mitochondrial pathway, induced by compressive stress, may be involved in tumor dormancy, in which tumor growth is held in check by a balance of apoptosis and proliferation.

  2. Coral bleaching under thermal stress: putative involvement of host/symbiont recognition mechanisms.

    Science.gov (United States)

    Vidal-Dupiol, Jeremie; Adjeroud, Mehdi; Roger, Emmanuel; Foure, Laurent; Duval, David; Mone, Yves; Ferrier-Pages, Christine; Tambutte, Eric; Tambutte, Sylvie; Zoccola, Didier; Allemand, Denis; Mitta, Guillaume

    2009-08-04

    Coral bleaching can be defined as the loss of symbiotic zooxanthellae and/or their photosynthetic pigments from their cnidarian host. This major disturbance of reef ecosystems is principally induced by increases in water temperature. Since the beginning of the 1980s and the onset of global climate change, this phenomenon has been occurring at increasing rates and scales, and with increasing severity. Several studies have been undertaken in the last few years to better understand the cellular and molecular mechanisms of coral bleaching but the jigsaw puzzle is far from being complete, especially concerning the early events leading to symbiosis breakdown. The aim of the present study was to find molecular actors involved early in the mechanism leading to symbiosis collapse. In our experimental procedure, one set of Pocillopora damicornis nubbins was subjected to a gradual increase of water temperature from 28 degrees C to 32 degrees C over 15 days. A second control set kept at constant temperature (28 degrees C). The differentially expressed mRNA between the stressed states (sampled just before the onset of bleaching) and the non stressed states (control) were isolated by Suppression Subtractive Hybridization. Transcription rates of the most interesting genes (considering their putative function) were quantified by Q-RT-PCR, which revealed a significant decrease in transcription of two candidates six days before bleaching. RACE-PCR experiments showed that one of them (PdC-Lectin) contained a C-Type-Lectin domain specific for mannose. Immunolocalisation demonstrated that this host gene mediates molecular interactions between the host and the symbionts suggesting a putative role in zooxanthellae acquisition and/or sequestration. The second gene corresponds to a gene putatively involved in calcification processes (Pdcyst-rich). Its down-regulation could reflect a trade-off mechanism leading to the arrest of the mineralization process under stress. Under thermal stress

  3. Coral bleaching under thermal stress: putative involvement of host/symbiont recognition mechanisms

    Directory of Open Access Journals (Sweden)

    Tambutte Sylvie

    2009-08-01

    Full Text Available Abstract Background Coral bleaching can be defined as the loss of symbiotic zooxanthellae and/or their photosynthetic pigments from their cnidarian host. This major disturbance of reef ecosystems is principally induced by increases in water temperature. Since the beginning of the 1980s and the onset of global climate change, this phenomenon has been occurring at increasing rates and scales, and with increasing severity. Several studies have been undertaken in the last few years to better understand the cellular and molecular mechanisms of coral bleaching but the jigsaw puzzle is far from being complete, especially concerning the early events leading to symbiosis breakdown. The aim of the present study was to find molecular actors involved early in the mechanism leading to symbiosis collapse. Results In our experimental procedure, one set of Pocillopora damicornis nubbins was subjected to a gradual increase of water temperature from 28°C to 32°C over 15 days. A second control set kept at constant temperature (28°C. The differentially expressed mRNA between the stressed states (sampled just before the onset of bleaching and the non stressed states (control were isolated by Suppression Subtractive Hybridization. Transcription rates of the most interesting genes (considering their putative function were quantified by Q-RT-PCR, which revealed a significant decrease in transcription of two candidates six days before bleaching. RACE-PCR experiments showed that one of them (PdC-Lectin contained a C-Type-Lectin domain specific for mannose. Immunolocalisation demonstrated that this host gene mediates molecular interactions between the host and the symbionts suggesting a putative role in zooxanthellae acquisition and/or sequestration. The second gene corresponds to a gene putatively involved in calcification processes (Pdcyst-rich. Its down-regulation could reflect a trade-off mechanism leading to the arrest of the mineralization process under stress

  4. Sustained Inflation at Birth Did Not Alter Lung Injury from Mechanical Ventilation in Surfactant-Treated Fetal Lambs

    Science.gov (United States)

    Hillman, Noah H.; Kemp, Matthew W.; Miura, Yuichiro; Kallapur, Suhas G.; Jobe, Alan H.

    2014-01-01

    Background Sustained inflations (SI) are used with the initiation of ventilation at birth to rapidly recruit functional residual capacity and may decrease lung injury and the need for mechanical ventilation in preterm infants. However, a 20 second SI in surfactant-deficient preterm lambs caused an acute phase injury response without decreasing lung injury from subsequent mechanical ventilation. Hypothesis A 20 second SI at birth will decrease lung injury from mechanical ventilation in surfactant-treated preterm fetal lambs. Methods The head and chest of fetal sheep at 126±1 day GA were exteriorized, with tracheostomy and removal of fetal lung fluid prior to treatment with surfactant (300 mg in 15 ml saline). Fetal lambs were randomized to one of four 15 minute interventions: 1) PEEP 8 cmH2O; 2) 20 sec SI at 40 cmH2O, then PEEP 8 cmH2O; 3) mechanical ventilation with 7 ml/kg tidal volume; or 4) 20 sec SI then mechanical ventilation at 7 ml/kg. Fetal lambs remained on placental support for the intervention and for 30 min after the intervention. Results SI recruited a mean volume of 6.8±0.8 mL/kg. SI did not alter respiratory physiology during mechanical ventilation. Heat shock protein (HSP) 70, HSP60, and total protein in lung fluid similarly increased in both ventilation groups. Modest pro-inflammatory cytokine and acute phase responses, with or without SI, were similar with ventilation. SI alone did not increase markers of injury. Conclusion In surfactant treated fetal lambs, a 20 sec SI did not alter ventilation physiology or markers of lung injury from mechanical ventilation. PMID:25419969

  5. Oxidative stress protection and stomatal patterning as components of salinity tolerance mechanism in quinoa (Chenopodium quinoa).

    Science.gov (United States)

    Shabala, Lana; Mackay, Alex; Tian, Yu; Jacobsen, Sven-Erik; Zhou, Daowei; Shabala, Sergey

    2012-09-01

    Two components of salinity stress are a reduction in water availability to plants and the formation of reactive oxygen species. In this work, we have used quinoa (Chenopodium quinoa), a dicotyledonous C3 halophyte species displaying optimal growth at approximately 150 mM NaCl, to study mechanisms by which halophytes cope with the afore-mentioned components of salt stress. The relative contribution of organic and inorganic osmolytes in leaves of different physiological ages (e.g. positions on the stem) was quantified and linked with the osmoprotective function of organic osmolytes. We show that the extent of the oxidative stress (UV-B irradiation) damage to photosynthetic machinery in young leaves is much less when compared with old leaves, and attribute this difference to the difference in the size of the organic osmolyte pool (1.5-fold difference under control conditions; sixfold difference in plants grown at 400 mM NaCl). Consistent with this, salt-grown plants showed higher Fv/Fm values compared with control plants after UV-B exposure. Exogenous application of physiologically relevant concentrations of glycine betaine substantially mitigated oxidative stress damage to PSII, in a dose-dependent manner. We also show that salt-grown plants showed a significant (approximately 30%) reduction in stomatal density observed in all leaves. It is concluded that accumulation of organic osmolytes plays a dual role providing, in addition to osmotic adjustment, protection of photosynthetic machinery against oxidative stress in developing leaves. It is also suggested that salinity-induced reduction in stomatal density represents a fundamental mechanism by which plants optimize water use efficiency under saline conditions. Copyright © Physiologia Plantarum 2012.

  6. Overlapping mechanisms of stress-induced relapse to opioid use disorder and chronic pain: Clinical implications

    Directory of Open Access Journals (Sweden)

    Udi E Ghitza

    2016-05-01

    Full Text Available Over the past two decades, a steeply growing number of persons with chronic non-cancer pain have been using opioid analgesics chronically to treat it, accompanied by a markedly increased prevalence of individuals with opioid-related misuse, opioid use disorders, emergency department visits, hospitalizations, admissions to drug treatment programs, and drug overdose deaths. This opioid misuse and overdose epidemic calls for well-designed randomized-controlled clinical trials into more skillful and appropriate pain management and for developing effective analgesics which have lower abuse liability and are protective against stress induced by chronic non-cancer pain. However, incomplete knowledge regarding effective approaches to treat various types of pain has been worsened by an under-appreciation of overlapping neurobiological mechanisms of stress, stress-induced relapse to opioid use, and chronic non-cancer pain in patients presenting for care for these conditions. This insufficient knowledge base has unfortunately encouraged common prescription of conveniently-available opioid pain-relieving drugs with abuse liability, as opposed to treating underlying problems using team-based multidisciplinary, patient-centered, collaborative-care approaches for addressing pain and co-occurring stress and risk for opioid use disorder. This paper reviews recent neurobiological findings regarding overlapping mechanisms of stress-induced relapse to opioid misuse and chronic non-cancer pain, and then discusses these in the context of key outstanding evidence gaps and clinical-treatment research directions which may be pursued to fill these gaps. Such research directions, if conducted through well-designed randomized controlled trials, may substantively inform clinical practice in general medical settings on how to effectively care for patients presenting with pain-related distress and these common co-occurring conditions.

  7. Clonal Plasticity of Aquatic Plant Species Submitted to Mechanical Stress: Escape versus Resistance Strategy

    Science.gov (United States)

    Puijalon, Sara; Bouma, Tjeerd J.; Van Groenendael, Jan; Bornette, Gudrun

    2008-01-01

    Background and Aims The plastic alterations of clonal architecture are likely to have functional consequences, as they affect the spatial distribution of ramets over patchy environments. However, little is known about the effect of mechanical stresses on the clonal growth. The aim of the present study was to investigate the clonal plasticity induced by mechanical stress consisting of continuous water current encountered by aquatic plants. More particularly, the aim was to test the capacity of the plants to escape this stress through clonal plastic responses. Methods The transplantation of ramets of the same clone in two contrasting flow velocity conditions was carried out for two species (Potamogeton coloratus and Mentha aquatica) which have contrasting clonal growth forms. Relative allocation to clonal growth, to creeping stems in the clonal biomass, number and total length of creeping stems, spacer length and main creeping stem direction were measured. Key Results For P. coloratus, plants exposed to water current displayed increased total length of creeping stems, increased relative allocation to creeping stems within the clonal dry mass and increased spacer length. For M. aquatica, plants exposed to current displayed increased number and total length of creeping stems. Exposure to current induced for both species a significant increase of the proportion of creeping stems in the downstream direction to the detriment of creeping stems perpendicular to flow. Conclusions This study demonstrates that mechanical stress from current flow induced plastic variation in clonal traits for both species. The responses of P. coloratus could lead to an escape strategy, with low benefits with respect to sheltering and anchorage. The responses of M. aquatica that may result in a denser canopy and enhancement of anchorage efficiency could lead to a resistance strategy. PMID:18854376

  8. Genomic Comparison of Indigenous African and Northern European Chickens Reveals Putative Mechanisms of Stress Tolerance Related to Environmental Selection Pressure.

    Science.gov (United States)

    Fleming, Damarius S; Weigend, Steffen; Simianer, Henner; Weigend, Annett; Rothschild, Max; Schmidt, Carl; Ashwell, Chris; Persia, Mike; Reecy, James; Lamont, Susan J

    2017-05-05

    Global climate change is increasing the magnitude of environmental stressors, such as temperature, pathogens, and drought, that limit the survivability and sustainability of livestock production. Poultry production and its expansion is dependent upon robust animals that are able to cope with stressors in multiple environments. Understanding the genetic strategies that indigenous, noncommercial breeds have evolved to survive in their environment could help to elucidate molecular mechanisms underlying biological traits of environmental adaptation. We examined poultry from diverse breeds and climates of Africa and Northern Europe for selection signatures that have allowed them to adapt to their indigenous environments. Selection signatures were studied using a combination of population genomic methods that employed FST , integrated haplotype score (iHS), and runs of homozygosity (ROH) procedures. All the analyses indicated differences in environment as a driver of selective pressure in both groups of populations. The analyses revealed unique differences in the genomic regions under selection pressure from the environment for each population. The African chickens showed stronger selection toward stress signaling and angiogenesis, while the Northern European chickens showed more selection pressure toward processes related to energy homeostasis. The results suggest that chromosomes 2 and 27 are the most diverged between populations and the most selected upon within the African (chromosome 27) and Northern European (chromosome 2) birds. Examination of the divergent populations has provided new insight into genes under possible selection related to tolerance of a population's indigenous environment that may be baselines for examining the genomic contribution to tolerance adaptions. Copyright © 2017 Fleming et al.

  9. Genomic Comparison of Indigenous African and Northern European Chickens Reveals Putative Mechanisms of Stress Tolerance Related to Environmental Selection Pressure

    Directory of Open Access Journals (Sweden)

    Damarius S. Fleming

    2017-05-01

    Full Text Available Global climate change is increasing the magnitude of environmental stressors, such as temperature, pathogens, and drought, that limit the survivability and sustainability of livestock production. Poultry production and its expansion is dependent upon robust animals that are able to cope with stressors in multiple environments. Understanding the genetic strategies that indigenous, noncommercial breeds have evolved to survive in their environment could help to elucidate molecular mechanisms underlying biological traits of environmental adaptation. We examined poultry from diverse breeds and climates of Africa and Northern Europe for selection signatures that have allowed them to adapt to their indigenous environments. Selection signatures were studied using a combination of population genomic methods that employed FST, integrated haplotype score (iHS, and runs of homozygosity (ROH procedures. All the analyses indicated differences in environment as a driver of selective pressure in both groups of populations. The analyses revealed unique differences in the genomic regions under selection pressure from the environment for each population. The African chickens showed stronger selection toward stress signaling and angiogenesis, while the Northern European chickens showed more selection pressure toward processes related to energy homeostasis. The results suggest that chromosomes 2 and 27 are the most diverged between populations and the most selected upon within the African (chromosome 27 and Northern European (chromosome 2 birds. Examination of the divergent populations has provided new insight into genes under possible selection related to tolerance of a population’s indigenous environment that may be baselines for examining the genomic contribution to tolerance adaptions.

  10. Translating the “Banana Genome” to Delineate Stress Resistance, Dwarfing, Parthenocarpy and Mechanisms of Fruit Ripening

    Directory of Open Access Journals (Sweden)

    Prasanta K Dash

    2016-10-01

    Full Text Available Evolutionary frozen, genetically sterile and globally iconic fruit Banana entered the genomics era with decoding of structural genome of double haploid Pahang (AA genome constitution genotype of M. acuminata. This wonder crop, as of today, remains untouched by the green revolution and researchers face intrinsic impediments for varietal improvement to enhance its yield. The complex genome of banana was decoded by hybrid sequencing strategies revealed panoply of genes and transcription factors involved in the process of sucrose conversion that imparts sweetness to its fruit. Banana has historically faced the wrath of pandemic bacterial, fungal and viral diseases and multitude of abiotic stresses that has ruined the livelihood of small and marginal farmers’ and destroyed commercial plantations. Decoding of its structural genome has given impetus to a deeper understanding of the repertoire of genes involved in disease resistance, understanding the mechanism of dwarfing to develop an ideal plant type, unravelling the process of parthenocarpy for better fruit quality, and fruit ripening in this climacteric fruit. Injunction of comparative genomics research will usher in to integrate information from its decoded genome and other monocots into field applications in banana related but not limited to yield enhancement, food security, livelihood assurance, and energy sustainability. In this mini review, we discuss pre- and post-genomic discoveries and highlight accomplishments in structural genomics, genetic engineering and forward genetic accomplishments with an aim to target genes and transcription factors for translational research in banana.

  11. Thermal-Mechanical Stress Analysis of PWR Pressure Vessel and Nozzles under Grid Load-Following Mode: Interim Report on the Effect of Cyclic Hardening Material Properties and Pre-existing Cracks on Stress Analysis Results

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, Subhasish [Argonne National Lab. (ANL), Argonne, IL (United States); Soppet, William [Argonne National Lab. (ANL), Argonne, IL (United States); Majumdar, Saurin [Argonne National Lab. (ANL), Argonne, IL (United States); Natesan, Ken [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-03-15

    This report provides an update on an assessment of environmentally assisted fatigue for light water reactor components under extended service conditions. This report is a deliverable under the work package for environmentally assisted fatigue as part of DOE’s Light Water Reactor Sustainability Program. In a previous report (September 2015), we presented tensile and fatigue test data and related hardening material properties for 508 low-alloys steel base metal and other reactor metals. In this report, we present thermal-mechanical stress analysis of the reactor pressure vessel and its hot-leg and cold-leg nozzles based on estimated material properties. We also present results from thermal and thermal-mechanical stress analysis under reactor heat-up, cool-down, and grid load-following conditions. Analysis results are given with and without the presence of preexisting cracks in the reactor nozzles (axial or circumferential crack). In addition, results from validation stress analysis based on tensile and fatigue experiments are reported.

  12. Endoplasmic reticulum stress-sensing mechanism is activated in Entamoeba histolytica upon treatment with nitric oxide.

    Directory of Open Access Journals (Sweden)

    Julien Santi-Rocca

    Full Text Available The Endoplasmic Reticulum stores calcium and is a site of protein synthesis and modification. Changes in ER homeostasis lead to stress responses with an activation of the unfolded protein response (UPR. The Entamoeba histolytica endomembrane system is simple compared to those of higher eukaryotes, as a canonical ER is not observed. During amoebiasis, an infection of the human intestine and liver by E. histolytica, nitric oxide (NO triggers an apoptotic-like event preceded by an impairment of energy production and a loss of important parasite pathogenic features. We address the question of how this ancient eukaryote responds to stress induced by immune components (i.e. NO and whether stress leads to ER changes and subsequently to an UPR. Gene expression analysis suggested that NO triggers stress responses marked by (i dramatic up-regulation of hsp genes although a bona fide UPR is absent; (ii induction of DNA repair and redox gene expression and iii up-regulation of glycolysis-related gene expression. Enzymology approaches demonstrate that NO directly inhibits glycolysis and enhance cysteine synthase activity. Using live imaging and confocal microscopy we found that NO dramatically provokes extensive ER fragmentation. ER fission in E. histolytica appears as a protective response against stress, as it has been recently proposed for neuron self-defense during neurologic disorders. Chronic ER stress is also involved in metabolic diseases including diabetes, where NO production reduces ER calcium levels and activates cell death. Our data highlighted unique cellular responses of interest to understand the mechanisms of parasite death during amoebiasis.

  13. Targeting Cellular Stress Mechanisms and Metabolic Homeostasis by Chinese Herbal Drugs for Neuroprotection

    Directory of Open Access Journals (Sweden)

    Hsiao-Chien Ting

    2018-01-01

    Full Text Available Traditional Chinese medicine has been practiced for centuries in East Asia. Herbs are used to maintain health and cure disease. Certain Chinese herbs are known to protect and improve the brain, memory, and nervous system. To apply ancient knowledge to modern science, some major natural therapeutic compounds in herbs were extracted and evaluated in recent decades. Emerging studies have shown that herbal compounds have neuroprotective effects or can ameliorate neurodegenerative diseases. To understand the mechanisms of herbal compounds that protect against neurodegenerative diseases, we summarize studies that discovered neuroprotection by herbal compounds and compound-related mechanisms in neurodegenerative disease models. Those compounds discussed herein show neuroprotection through different mechanisms, such as cytokine regulation, autophagy, endoplasmic reticulum (ER stress, glucose metabolism, and synaptic function. The interleukin (IL-1β and tumor necrosis factor (TNF-α signaling pathways are inhibited by some compounds, thus attenuating the inflammatory response and protecting neurons from cell death. As to autophagy regulation, herbal compounds show opposite regulatory effects in different neurodegenerative models. Herbal compounds that inhibit ER stress prevent neuronal death in neurodegenerative diseases. Moreover, there are compounds that protect against neuronal death by affecting glucose metabolism and synaptic function. Since the progression of neurodegenerative diseases is complicated, and compound-related mechanisms for neuroprotection differ, therapeutic strategies may need to involve multiple compounds and consider the type and stage of neurodegenerative diseases.

  14. Immunohistochemical expression of heat shock proteins in the mouse periodontal tissues due to orthodontic mechanical stress*

    Directory of Open Access Journals (Sweden)

    Muraoka R

    2010-11-01

    Full Text Available Abstract The histopathology of periodontal ligament of the mouse subjected to mechanical stress was studied. Immunohistochemical expressions of HSP27 and pHSP27 were examined. Experimental animals using the maxillary molars of ddY mouse by Waldo method were used in the study. A separator was inserted to induce mechanical stress. After 10 minutes, 20 minutes, 1 hour, 3 hours, 9 hours and 24 hours, the regional tissues were extracted, fixed in 4% paraformaldehyde and 0.05 M phosphate-buffered fixative solution. Paraffin sections were made for immunohistochemistry using HSP27 and p-HSP27. In the control group, the periodontal ligament fibroblasts expressed low HSP27 and p-HSP27. However, in the experimental group, periodontal ligament fibroblasts expressed HSP27 10 minutes after mechanical load application in the tension side. The strongest expression was detected 9 hours after inducing mechanical load. p-HSP27 was also expressed in a time-dependent manner though weaker than HSP27. The findings suggest that HSP27 and p-HSP27 were expressed for the maintenance of homeostasis of periodontal ligament by the activation of periodontal ligament fibroblasts on the tension side. It also suggests that these proteins act as molecular chaperones for osteoblast activation and maintenance of homeostasis.

  15. Mechanical stress as the common denominator between chronic inflammation, cancer and Alzheimer’s disease

    Directory of Open Access Journals (Sweden)

    Marcel eLevy Nogueira

    2015-09-01

    Full Text Available The pathogenesis of common diseases such as Alzheimer’s disease (AD and cancer are currently poorly understood. Inflammation is a common risk factor for cancer and AD. Recent data, provided by our group and from others, demonstrate that increased pressure and inflammation are synonymous. There is a continuous increase in pressure from inflammation to fibrosis and then cancer. This in line with the numerous papers reporting high interstitial pressure in cancer. But most authors focus on the role of pressure in the lack of delivery of chemotherapy in the center of the tumor. Pressure may also be a key factor in carcinogenesis. Increased pressure is responsible for oncogene activation and cytokine secretion. Accumulation of mechanical stress plays a key role in the development of diseases of old age such as cardiomyopathy, atherosclerosis and osteoarthritis. Growing evidence suggest also a possible link between mechanical stress in the pathogenesis of AD. The aim of this review is to describe environmental and endogenous mechanical factors possibly playing a pivotal role in the mechanism of chronic inflammation, AD and cancer.

  16. Causes, Effects of Stress and the Coping Mechanism of the Bachelor of Science in Information Technology Students in a Philippine University

    National Research Council Canada - National Science Library

    Generoso N. Mazo

    2015-01-01

    .... This study sought to determine the causes of stress, the effects of stress, and the stress coping mechanisms of Bachelor of Science in Information Technology students in the Leyte Normal University, Tacloban City...

  17. Focal mechanism and stress analyses for main tectonic zones in Albania

    Science.gov (United States)

    Dushi, Edmond; Koçi, Rexhep; Begu, Enkela; Bozo, Rrezart

    2017-04-01

    In this study, a number of 33 moderate earthquakes for the period 2013-2015, ranging in magnitude within 2.2 ≤ MW ≤ 4.9 and located within the Albanian territory, have been analyzed. As an earthquake prone country, situated at the frontal collision boundary between Adria microplate and Eurasian tectonic plate, Albania is characterized frequently by micro earthquakes, many moderate and seldom by strong ones. It is evidenced that the whole territory is divided in two different tectonic domains, correspondingly the outer and the inner domain, showing different stress regime as clearly evidenced based on earthquake focal mechanism and geodetic studies. Although strong earthquakes are clearly related to faults in tectonically active areas, moderate events are more frequent revealing valuable information on this purpose. All the studied events are selected to be well-recorded by a maximum possible number of the local broadband (BB) seismological stations of Albanian Seismological Network (ASN), although regional stations have been used as well to constrain the solution. Earthquakes are grouped according to their location, within three well-defined tectonic zones, namely: Adriatic-Ionian (AI), Lushnja-Elbasani-Dibra (LED) and Ohrid-Korça (OK). For each event, the seismic moment M0is determined, through spectral analyses. Moment values vary ranging 1012 - 1015 Nm, for the Adriatic-Ionian (AI) outer zone; 1013 - 1016 Nm, for the Lushnja-Elbasani-Dibra (LED) transversal zone, which cuts through both the outer and the inner domains and 1012 - 1014 Nm, for the Ohrid-Korça (OK), north-south trending inner zone. Focal mechanism solutions (FMS) have been determined for each earthquake, based on the robust first motion polarities method, as applied in the FOCMEC (Seisan 10.1) routine. Using the Michael's linear bootstrap invertion on FMS, a stress analysis is applied. Results show the minimum compressional stress directions variation: σ1 370/270, σ23030/80 and σ31980

  18. Mechanisms of Action Involved in Ozone Therapy: Is healing induced via a mild oxidative stress?

    Directory of Open Access Journals (Sweden)

    Sagai Masaru

    2011-12-01

    Full Text Available Abstract The potential mechanisms of action of ozone therapy are reviewed in this paper. The therapeutic efficacy of ozone therapy may be partly due the controlled and moderate oxidative stress produced by the reactions of ozone with several biological components. The line between effectiveness and toxicity of ozone may be dependent on the strength of the oxidative stress. As with exercise, it is well known that moderate exercise is good for health, whereas excessive exercise is not. Severe oxidative stress activates nuclear transcriptional factor kappa B (NFκB, resulting in an inflammatory response and tissue injury via the production of COX2, PGE2, and cytokines. However, moderate oxidative stress activates another nuclear transcriptional factor, nuclear factor-erythroid 2-related factor 2 (Nrf2. Nrf2 then induces the transcription of antioxidant response elements (ARE. Transcription of ARE results in the production of numerous antioxidant enzymes, such as SOD, GPx, glutathione-s-transferase(GSTr, catalase (CAT, heme-oxygenase-1 (HO-1, NADPH-quinone-oxidoreductase (NQO-1, phase II enzymes of drug metabolism and heat shock proteins (HSP. Both free antioxidants and anti-oxidative enzymes not only protect cells from oxidation and inflammation but they may be able to reverse the chronic oxidative stress. Based on these observations, ozone therapy may also activate Nrf2 via moderate oxidative stress, and suppress NFκB and inflammatory responses. Furthermore, activation of Nrf2 results in protection against neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases. Mild immune responses are induced via other nuclear transcriptional factors, such as nuclear factor of activated T-cells (NFAT and activated protein-1 (AP-1. Additionally, the effectiveness of ozone therapy in vascular diseases may also be explained by the activation of another nuclear transcriptional factor, hypoxia inducible factor-1α (HIF-1a, which is also induced via

  19. Mechanisms of Action Involved in Ozone Therapy: Is healing induced via a mild oxidative stress?

    Science.gov (United States)

    Sagai, Masaru; Bocci, Velio

    2011-12-20

    The potential mechanisms of action of ozone therapy are reviewed in this paper. The therapeutic efficacy of ozone therapy may be partly due the controlled and moderate oxidative stress produced by the reactions of ozone with several biological components. The line between effectiveness and toxicity of ozone may be dependent on the strength of the oxidative stress. As with exercise, it is well known that moderate exercise is good for health, whereas excessive exercise is not.Severe oxidative stress activates nuclear transcriptional factor kappa B (NFκB), resulting in an inflammatory response and tissue injury via the production of COX2, PGE2, and cytokines. However, moderate oxidative stress activates another nuclear transcriptional factor, nuclear factor-erythroid 2-related factor 2 (Nrf2). Nrf2 then induces the transcription of antioxidant response elements (ARE). Transcription of ARE results in the production of numerous antioxidant enzymes, such as SOD, GPx, glutathione-s-transferase(GSTr), catalase (CAT), heme-oxygenase-1 (HO-1), NADPH-quinone-oxidoreductase (NQO-1), phase II enzymes of drug metabolism and heat shock proteins (HSP). Both free antioxidants and anti-oxidative enzymes not only protect cells from oxidation and inflammation but they may be able to reverse the chronic oxidative stress. Based on these observations, ozone therapy may also activate Nrf2 via moderate oxidative stress, and suppress NFκB and inflammatory responses. Furthermore, activation of Nrf2 results in protection against neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases. Mild immune responses are induced via other nuclear transcriptional factors, such as nuclear factor of activated T-cells (NFAT) and activated protein-1 (AP-1).Additionally, the effectiveness of ozone therapy in vascular diseases may also be explained by the activation of another nuclear transcriptional factor, hypoxia inducible factor-1α (HIF-1a), which is also induced via moderate oxidative

  20. Faulting mechanisms and stress regime at the European HDR site of Soultz-sous-Forets, France

    Energy Technology Data Exchange (ETDEWEB)

    Cuenot, Nicolas; Charlety, Jean; Haessler, Henri [Institut de Physique du Globe de Strasbourg, Ecole et Observatoire des Sciences de la Terre (IPGS-EOST), 5 rue Rene Descartes, 67084 Strasbourg Cedex (France); Dorbath, Louis [Institut de Physique du Globe de Strasbourg, Ecole et Observatoire des Sciences de la Terre (IPGS-EOST), 5 rue Rene Descartes, 67084 Strasbourg Cedex (France); Institut de Recherche pour le Developpement, Laboratoire des Mecanismes et Transferts en Geologie (IRD, LMTG), 14 Avenue Edouard Belin, 31400 Toulouse (France)

    2006-10-15

    The state of stress and its implications for shear on fault planes during fluid injection are crucial issues for the HDR (Hot Dry Rock) or EGS (Enhanced or Engineered Geothermal System) concept. This is especially true for hydraulic stimulation experiments, aimed at enhancing the connectivity of a borehole to the natural fracture network, since they tend to induce the shearing of fractures, which is controlled by the local stress regime. During the 2000 and 2003 stimulation tests at Soultz-sous-Forets, France, about 10,000 microearthquakes were located with a surface seismological network. Hundreds of double-couple (DC) focal mechanisms were automatically determined from first-motion polarities using the FPFIT program [Reasenberg, P.A., Oppenheimer, D., 1985. FPFIT, FPPLOT and FPPAGE: Fortran computer programs for calculating and displaying earthquake fault-plane solutions. US Geological Survey Open-File Report 85-739, 25 pp.]. The majority of these mechanisms indicate normal-faulting movement with a more or less pronounced strike-slip component. Some quasi-pure strike-slip events also occurred, especially in the deeper part of the stimulated rock volume, at more than 5 km depth. Although we found a double-couple solution for all events, we tried to observe and quantify the proportion of the non-double-couple (NDC) component in the seismic moment tensor for several microseisms from the 2003 data. The study shows that the NDC is higher for the events in the vicinity of the injection well than for the events far from the well. We used the method of Rivera and Cisternas [Rivera, L., Cisternas, A., 1990. Stress tensor and fault-plane solutions for a population of earthquakes. Bull. Seismol. Soc. Am. 80, 600-614.] to perform the inversion of the deviatoric part of the stress tensor from P-wave polarities. This method was applied to different datasets from the 2000 test, taken from the shallower and deeper parts of the stimulated region. The results show a stable

  1. Mechanisms of Action Involved in Ozone Therapy: Is healing induced via a mild oxidative stress?

    Science.gov (United States)

    2011-01-01

    The potential mechanisms of action of ozone therapy are reviewed in this paper. The therapeutic efficacy of ozone therapy may be partly due the controlled and moderate oxidative stress produced by the reactions of ozone with several biological components. The line between effectiveness and toxicity of ozone may be dependent on the strength of the oxidative stress. As with exercise, it is well known that moderate exercise is good for health, whereas excessive exercise is not. Severe oxidative stress activates nuclear transcriptional factor kappa B (NFκB), resulting in an inflammatory response and tissue injury via the production of COX2, PGE2, and cytokines. However, moderate oxidative stress activates another nuclear transcriptional factor, nuclear factor-erythroid 2-related factor 2 (Nrf2). Nrf2 then induces the transcription of antioxidant response elements (ARE). Transcription of ARE results in the production of numerous antioxidant enzymes, such as SOD, GPx, glutathione-s-transferase(GSTr), catalase (CAT), heme-oxygenase-1 (HO-1), NADPH-quinone-oxidoreductase (NQO-1), phase II enzymes of drug metabolism and heat shock proteins (HSP). Both free antioxidants and anti-oxidative enzymes not only protect cells from oxidation and inflammation but they may be able to reverse the chronic oxidative stress. Based on these observations, ozone therapy may also activate Nrf2 via moderate oxidative stress, and suppress NFκB and inflammatory responses. Furthermore, activation of Nrf2 results in protection against neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases. Mild immune responses are induced via other nuclear transcriptional factors, such as nuclear factor of activated T-cells (NFAT) and activated protein-1 (AP-1). Additionally, the effectiveness of ozone therapy in vascular diseases may also be explained by the activation of another nuclear transcriptional factor, hypoxia inducible factor-1α (HIF-1a), which is also induced via moderate

  2. Light-sustained cooperative mechanisms observed at liquid junctions of chalcopyrite semiconductors

    Science.gov (United States)

    Cattarin, S.; Tributsch, H.

    1988-07-01

    Electrochemical oscillations previously shown to occur during hydrogen peroxide reduction of natural samples of copper-containing sulfides (e.g. Cu 5FeS 4) have also been produced with synthetic chalcopyrites (CuMeX 2 with Me=Fe, In, X=S, Se). It is possible partly to control this cooperative phenomenon by photoexcitation of p-type CuInS 2 and p-type CuInSe 2, semiconductor electrodes. With illumination as a key factor in the control of cooperative phenomena it should be possible to explore non-linear photoelectrochemical mechanisms with possible applications to solar energy conversion. The cooperative phenomenon studied involves the interaction of electrons with copper (in oxidation states I, II and III) and oxygen and thus might be related to the cooperative mechanism causing high-temperature superconduction in copper oxide phases.

  3. Stress

    Science.gov (United States)

    ... natural disaster. This type of stress can cause post-traumatic stress disorder (PTSD). Different people may feel stress in different ways. Some people experience digestive symptoms. Others may have headaches, sleeplessness, depressed mood, anger, ...

  4. Effect of Alkane Chain Length on Crystallization in Emulsions during Supercooling in Quiescent Systems and under Mechanical Stress

    Directory of Open Access Journals (Sweden)

    Serghei Abramov

    2018-01-01

    Full Text Available Crystallization behavior of hexadecane (C16H34, octadecane (C18H38, eicosane (C20H42, and docosane (C22H46 dispersions of similar mean droplet diameter (x50.2 ≈ 15 µm was investigated in quiescent systems and compared to crystallization under mechanical stress. In quiescent systems, the required supercooling decreased with increasing chain length of the alkanes to initiate crystallization. Crystallization of alkane dispersions under mechanical stress resulted in similar onset crystallization supercooling, as during quiescent crystallization. Increase of mechanical stress did not affect the onset crystallization supercooling within alkane dispersions.

  5. Deformation and Failure Mechanism of Roadway Sensitive to Stress Disturbance and Its Zonal Support Technology

    Directory of Open Access Journals (Sweden)

    Qiangling Yao

    2016-01-01

    Full Text Available The 6163 haulage roadway in the Qidong coal mine passes through a fault zone, which causes severe deformation in the surrounding rock, requiring repeated roadway repairs. Based on geological features in the fault area, we analyze the factors affecting roadway deformation and failure and propose the concept of roadway sensitive to stress disturbance (RSSD. We investigate the deformation and failure mechanism of the surrounding rocks of RSSD using field monitoring, theoretical analysis, and numerical simulation. The deformation of the surrounding rocks involves dilatation of shallow rocks and separation of deep rocks. Horizontal and longitudinal fissures evolve to bed separation and fracture zones; alternatively, fissures can evolve into fracture zones with new fissures extending to deeper rock. The fault affects the stress field of the surrounding rock to ~27 m radius. Its maximum impact is on the vertical stress of the rib rock mass and its minimum impact is on the vertical stress of the floor rock mass. Based on our results, we propose a zonal support system for a roadway passing through a fault. Engineering practice shows that the deformation of the surrounding rocks of the roadway can be effectively controlled to ensure normal and safe production in the mine.

  6. Adaptation of grapevine flowers to cold involves different mechanisms depending on stress intensity.

    Directory of Open Access Journals (Sweden)

    Mélodie Sawicki

    Full Text Available Grapevine flower development and fruit set are influenced by cold nights in the vineyard. To investigate the impact of cold stress on carbon metabolism in the inflorescence, we exposed the inflorescences of fruiting cuttings to chilling and freezing temperatures overnight and measured fluctuations in photosynthesis and sugar content. Whatever the temperature, after the stress treatment photosynthesis was modified in the inflorescence, but the nature of the alteration depended on the intensity of the cold stress. At 4°C, photosynthesis in the inflorescence was impaired through non-stomatal limitations, whereas at 0°C it was affected through stomatal limitations. A freezing night (-3°C severely deregulated photosynthesis in the inflorescence, acting primarily on photosystem II. Cold nights also induced accumulation of sugars. Soluble carbohydrates increased in inflorescences exposed to -3°C, 0°C and 4°C, but starch accumulated only in inflorescences of plants treated at 0 and -3°C. These results suggest that inflorescences are able to cope with cold temperatures by adapting their carbohydrate metabolism using mechanisms that are differentially induced according to stress intensity.

  7. Mechanisms of carbon nanotube-induced toxicity: Focus on oxidative stress

    Energy Technology Data Exchange (ETDEWEB)

    Shvedova, Anna A., E-mail: ats1@cdc.gov [Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, University of Rome “Tor Vergata”, Rome (Italy); Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, University of Rome “Tor Vergata”, Rome (Italy); Pietroiusti, Antonio [Department of Biopathology, University of Rome “Tor Vergata”, Rome (Italy); Fadeel, Bengt [Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm (Sweden); Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA (United States); Kagan, Valerian E. [Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA (United States)

    2012-06-01

    Nanotechnologies are emerging as highly promising technologies in many sectors in the society. However, the increasing use of engineered nanomaterials also raises concerns about inadvertent exposure to these materials and the potential for adverse effects on human health and the environment. Despite several years of intensive investigations, a common paradigm for the understanding of nanoparticle-induced toxicity remains to be firmly established. Here, the so-called oxidative stress paradigm is scrutinized. Does oxidative stress represent a secondary event resulting inevitably from disruption of biochemical processes and the demise of the cell, or a specific, non-random event that plays a role in the induction of cellular damage e.g. apoptosis? The answer to this question will have important ramifications for the development of strategies for mitigation of adverse effects of nanoparticles. Recent examples of global lipidomics studies of nanoparticle-induced tissue damage are discussed along with proteomics and transcriptomics approaches to achieve a comprehensive understanding of the complex and interrelated molecular changes in cells and tissues exposed to nanoparticles. We also discuss instances of non-oxidative stress-mediated cellular damage resulting from direct physical interference of nanomaterials with cellular structures. -- Highlights: ► CNT induced non-random oxidative stress associated with apoptosis. ► Non-oxidative mechanisms for cellular toxicity of carbon nanotubes. ► Biodegradation of CNT by cells of innate immune system. ► “Omics”-based biomarkers of CNT exposures.

  8. Transcriptomic profiling revealed the regulatory mechanism of Arabidopsis seedlings response to oxidative stress from cryopreservation.

    Science.gov (United States)

    Ren, Li; Zhang, Di; Chen, Guan-qun; Reed, Barbara M; Shen, Xiao-hui; Chen, Huo-ying

    2015-12-01

    Elevated antioxidant status and positive abiotic stress response in dehydration enhance cell resistance to cryoinjury, and controlling oxidative damage via reactive oxygen species homeostasis maintenance leads to high survival. Cryoprotectants are important for cell survival in cryopreservation, but high concentrations can also cause oxidative stress. Adding vitamin C to the cryoprotectant doubled the survival ratio in Arabidopsis thaliana 60-h seedlings (seedlings after 60-h germination) cryopreservation. In this study, the metabolites and transcriptional profiling of 60-h seedlings were analyzed in both the control cryopreservation procedure (CCP) and an improved cryopreservation procedure (ICP) to reveal the mechanism of plant cell response to oxidative stress from cryopreservation. Reactive oxygen species (ROS) and peroxidation levels reached a peak after rapid cooling-warming in CCP, which were higher than that in ICP. In addition, gene regulation was significantly increased in CCP and decreased in ICP during rapid cooling-warming. Before cryogenic treatment, the number of specifically regulated genes was nearly 10 times higher in ICP dehydration than CCP dehydration. Among these genes, DREBs/CBFs were beneficial to cope with cryoinjury, and calcium-binding protein, OXI1, WRKY and MYB family members as key factors in ROS signal transduction activated the ROS-producing and ROS-scavenging networks including AsA-GSH and GPX cycles involved in scavenging H2O2. Finally, elevated antioxidant status and oxidative stress response in the improved dehydration enhanced seedling resistance to cryogenic treatment, maintained ROS homeostasis and improved cell recovery after cryopreservation.

  9. Incision and stress regulation in borderline personality disorder: neurobiological mechanisms of self-injurious behaviour.

    Science.gov (United States)

    Reitz, Sarah; Kluetsch, Rosemarie; Niedtfeld, Inga; Knorz, Teresa; Lis, Stefanie; Paret, Christian; Kirsch, Peter; Meyer-Lindenberg, Andreas; Treede, Rolf-Detlef; Baumgärtner, Ulf; Bohus, Martin; Schmahl, Christian

    2015-08-01

    Patients with borderline personality disorder frequently show non-suicidal self-injury (NSSI). In these patients, NSSI often serves to reduce high levels of stress. Investigation of neurobiological mechanisms of NSSI in borderline personality disorder. In total, 21 women with borderline personality disorder and 17 healthy controls underwent a stress induction, followed by either an incision into the forearm or a sham treatment. Afterwards participants underwent resting-state functional magnetic resonance imaging while aversive tension, heart rate and heart rate variability were assessed. We found a significant influence of incision on subjective and objective stress levels with a stronger decrease of aversive tension in the borderline personality disorder group following incision than sham. Amygdala activity decreased more and functional connectivity with superior frontal gyrus normalised after incision in the borderline personality disorder group. Decreased stress levels and amygdala activity after incision support the assumption of an influence of NSSI on emotion regulation in individuals with borderline personality disorder and aids in understanding why these patients use self-inflicted pain to reduce inner tension. © The Royal College of Psychiatrists 2015.

  10. Mechanisms of age-related cognitive change and targets for intervention: social interactions and stress.

    Science.gov (United States)

    Kremen, William S; Lachman, Margie E; Pruessner, Jens C; Sliwinski, Martin; Wilson, Robert S

    2012-06-01

    The effects of biological and physical factors on cognitive aging are widely studied. Less is known about the role of psychosocial factors such as stress and social relationships for cognitive functioning. Speakers in Session IV of the Summit focused on possible mechanisms linking social interactions and stressful experiences to cognitive changes with aging. Elevated cortisol, repetitive thinking, negative emotions, neuroticism, chronic stress, and early life adversity were negatively associated with memory and other cognitive dimensions in later life. In contrast, supportive social relationships were found to be positively related to cognitive functioning. Some evidence was provided for multidirectional, causal relationships involving stress and negative affect as both antecedents and consequences of cognitive decline. The findings contribute to understanding the potential underlying causal processes linking psychosocial factors and cognitive aging with a developmental focus on the etiology of declines and onset of cognitive impairments. This work provides an important foundation for future research to identify modifiable factors and to design interventions to minimize cognitive declines and optimize cognitive health in adulthood.

  11. Glucocorticoid Mechanisms of Functional Connectivity Changes in Stress-Related Neuropsychiatric Disorders.

    Science.gov (United States)

    Hall, Baila S; Moda, Rachel N; Liston, Conor

    2015-01-01

    Stress-especially chronic, uncontrollable stress-is an important risk factor for many neuropsychiatric disorders. The underlying mechanisms are complex and multifactorial, but they involve correlated changes in structural and functional measures of neuronal connectivity within cortical microcircuits and across neuroanatomically distributed brain networks. Here, we review evidence from animal models and human neuroimaging studies implicating stress-associated changes in functional connectivity in the pathogenesis of PTSD, depression, and other neuropsychiatric conditions. Changes in fMRI measures of corticocortical connectivity across distributed networks may be caused by specific structural alterations that have been observed in the prefrontal cortex, hippocampus, and other vulnerable brain regions. These effects are mediated in part by glucocorticoids, which are released from the adrenal gland in response to a stressor and also oscillate in synchrony with diurnal rhythms. Recent work indicates that circadian glucocorticoid oscillations act to balance synapse formation and pruning after learning and during development, and chronic stress disrupts this balance. We conclude by considering how disrupted glucocorticoid oscillations may contribute to the pathophysiology of depression and PTSD in vulnerable individuals, and how circadian rhythm disturbances may affect non-psychiatric populations, including frequent travelers, shift workers, and patients undergoing treatment for autoimmune disorders.

  12. Novel mechanical bioreactor for concomitant fluid shear stress and substrate strain.

    Science.gov (United States)

    Van Dyke, William S; Sun, Xuanhao; Richard, A Benjamin; Nauman, Eric A; Akkus, Ozan

    2012-04-30

    The two main types of mechanical stimuli used in cellular-level bone mechanotransduction studies are substrate strain and flow-induced shear stress. A subset of studies has investigated which of these stimuli induces the primary mechanotransduction effect on bone cells. The shortcomings of these experiments are twofold. First, in some experiments the magnitude of one loading type is able to be quantitatively measured while the other loading mode is only estimated. Second, the two loading modes are compared using different bioreactors, representing different cellular environments and substrates to which the cells are attached. In addition, none of these studies utilized bioreactors which apply controlled magnitudes of substrate strain and flow-induced shear stress differentially and simultaneously. This study presents the design of a multimodal loading device which can apply substrate stretch and fluid flow simultaneously while allowing for real-time cell imaging. The mechanical performance of the bioreactor is validated in this study by correlating the output levels of flow-induced shear stress and substrate strain with the input levels of displacement and displacement rate. The magnitudes of cross-talk loading (i.e. flow-induced strain, and strain-induced fluid flow) are also characterized and shown to be magnitudes lower than physiological levels of loading estimated to occur in bone in vivo. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Cadmium stress in rice: toxic effects, tolerance mechanisms, and management: a critical review.

    Science.gov (United States)

    Rizwan, Muhammad; Ali, Shafaqat; Adrees, Muhammad; Rizvi, Hina; Zia-Ur-Rehman, Muhammad; Hannan, Fakhir; Qayyum, Muhammad Farooq; Hafeez, Farhan; Ok, Yong Sik

    2016-09-01

    Cadmium (Cd) is one of the main pollutants in paddy fields, and its accumulation in rice (Oryza sativa L.) and subsequent transfer to food chain is a global environmental issue. This paper reviews the toxic effects, tolerance mechanisms, and management of Cd in a rice paddy. Cadmium toxicity decreases seed germination, growth, mineral nutrients, photosynthesis, and grain yield. It also causes oxidative stress and genotoxicity in rice. Plant response to Cd toxicity varies with cultivars, growth condition, and duration of Cd exposure. Under Cd stress, stimulation of antioxidant defense system, osmoregulation, ion homeostasis, and over production of signaling molecules are important tolerance mechanisms in rice. Several strategies have been proposed for the management of Cd-contaminated paddy soils. One such approach is the exogenous application of hormones, osmolytes, and signaling molecules. Moreover, Cd uptake and toxicity in rice can be decreased by proper application of essential nutrients such as nitrogen, zinc, iron, and selenium in Cd-contaminated soils. In addition, several inorganic (liming and silicon) and organic (compost and biochar) amendments have been applied in the soils to reduce Cd stress in rice. Selection of low Cd-accumulating rice cultivars, crop rotation, water management, and exogenous application of microbes could be a reasonable approach to alleviate Cd toxicity in rice. To draw a sound conclusion, long-term field trials are still required, including risks and benefit analysis for various management strategies.

  14. Characterization of Mechanical Properties and Residual Stress in API 5L X80 Steel Welded Joints

    Science.gov (United States)

    de Sousa Lins, Amilton; de Souza, Luís Felipe Guimarães; Fonseca, Maria Cindra

    2018-01-01

    The use of high-strength and low-alloy steels, high design factors and increasingly stringent safety requirements have increased the operating pressure levels and, consequently, the need for further studies to avoid and prevent premature pipe failure. To evaluate the possibility of improving productivity in manual arc welding of this type of steel, this work characterizes the mechanical properties and residual stresses in API 5L X80 steel welded joints using the SMAW and FCAW processes. The residual stresses were analyzed using x-ray diffraction with the sin2 ψ method at the top and root of the welded joints in the longitudinal and transverse directions of the weld bead. The mechanical properties of the welded joints by both processes were characterized in terms of tensile strength, impact toughness and Vickers microhardness in the welded and shot peening conditions. A predominantly compressive residual stress was found, and shot peening increased the tensile strength and impact toughness in both welded joints.

  15. Mechanical stress, fracture risk and beak evolution in Darwin's ground finches (Geospiza)

    Science.gov (United States)

    Soons, Joris; Herrel, Anthony; Genbrugge, Annelies; Aerts, Peter; Podos, Jeffrey; Adriaens, Dominique; de Witte, Yoni; Jacobs, Patric; Dirckx, Joris

    2010-01-01

    Darwin's finches have radiated from a common ancestor into 14 descendent species, each specializing on distinct food resources and evolving divergent beak forms. Beak morphology in the ground finches (Geospiza) has been shown to evolve via natural selection in response to variation in food type, food availability and interspecific competition for food. From a mechanical perspective, however, beak size and shape are only indirectly related to birds' abilities to crack seeds, and beak form is hypothesized to evolve mainly under selection for fracture avoidance. Here, we test the fracture-avoidance hypothesis using finite-element modelling. We find that across species, mechanical loading is similar and approaches reported values of bone strength, thus suggesting pervasive selection on fracture avoidance. Additionally, deep and wide beaks are better suited for dissipating stress than are more elongate beaks when scaled to common sizes and loadings. Our results illustrate that deep and wide beaks in ground finches enable reduction of areas with high stress and peak stress magnitudes, allowing birds to crack hard seeds while limiting the risk of beak failure. These results may explain strong selection on beak depth and width in natural populations of Darwin's finches. PMID:20194171

  16. Stress optimization of leaf-spring crossed flexure pivots for an active Gurney flap mechanism

    Science.gov (United States)

    Freire Gómez, Jon; Booker, Julian D.; Mellor, Phil H.

    2015-04-01

    The EU's Green Rotorcraft programme is pursuing the development of a functional and airworthy Active Gurney Flap (AGF) for a full-scale helicopter rotor blade. Interest in the development of this `smart adaptive rotor blade' technology lies in its potential to provide a number of aerodynamic benefits, which would in turn translate into a reduction in fuel consumption and noise levels. The AGF mechanism selected employs leaf-spring crossed flexure pivots. These provide important advantages over bearings as they are not susceptible to seizing and do not require maintenance (i.e. lubrication or cleaning). A baseline design of this mechanism was successfully tested both in a fatigue rig and in a 2D wind tunnel environment at flight-representative deployment schedules. For full validation, a flight test would also be required. However, the severity of the in-flight loading conditions would likely compromise the mechanical integrity of the pivots' leaf-springs in their current form. This paper investigates the scope for stress reduction through three-dimensional shape optimization of the leaf-springs of a generic crossed flexure pivot. To this end, a procedure combining a linear strain energy formulation, a parametric leaf-spring profile definition and a series of optimization algorithms is employed. The resulting optimized leaf-springs are proven to be not only independent of the angular rotation at which the pivot operates, but also linearly scalable to leaf-springs of any length, minimum thickness and width. Validated using non-linear finite element analysis, the results show very significant stress reductions relative to pivots with constant cross section leaf-springs, of up to as much as 30% for the specific pivot configuration employed in the AGF mechanism. It is concluded that shape optimization offers great potential for reducing stress in crossed flexure pivots and, consequently, for extending their fatigue life and/or rotational range.

  17. Bioactive Glass Nanoparticles as a New Delivery System for Sustained 5-Fluorouracil Release: Characterization and Evaluation of Drug Release Mechanism

    Directory of Open Access Journals (Sweden)

    Abeer M. El-Kady

    2015-01-01

    Full Text Available Bioactive glass nanoparticles were synthesized and tested for the first time as a new delivery system for sustained 5-fluorouracil (5-FU release. They were characterized by TEM, DTA, TGA, and FT-IR. The porosity % and specific surface area of glass nanoparticles were 85.59% and 378.36 m2/g, respectively. The in vitro bioactivity evaluation confirmed that bioactive glass disks prepared from these nanoparticles could induce hydroxyapatite layer over their surfaces in simulated body fluid. The in vitro drug release experiment indicated that glass nanoparticles could serve as long-term local delivery vehicles for sustained 5-FU release. The release profile of 5-FU showed an initial fast release stage followed by a second stage of slower release. The initial burst release of 5-FU in the first day was about 23% (28.92 mg·L−1 of the total amount of loaded 5-FU, while the final cumulative percentage of the 5-FU released after 32 days was about 45.6% (57.31 mg·L−1 of the total amount of loaded 5-FU. The application of different mathematical models indicated that 5-FU was released by diffusion controlled mechanism and suggested that its release rate was dependent on glass particles dissolution, changes of surface area as well as diameter of glass particles, and concentration of loaded drug.

  18. Eco-design of low energy mechanical milling through implementation of quality function deployment and design for sustainability

    Science.gov (United States)

    Rashid, Muhammad Hanif Abd; Nor, Nik Hisyamudin Muhd; Selamat, Siti Norhana; Hassan, Mohd Fahrul; Rahim, Abd Khalil Abd; Ahmad, Mohd Fauzi; Ismail, Al Emran; Omar, Badrul; Mokhtar, Mohd Faiz; Turan, Faiz Mohd; Yokoyama, Seiji

    2017-04-01

    Malaysia as a developing country favor energy demand by years which created mainly from fossil fuel. Unfortunately, the action leads to significant increment in carbon dioxide (CO2) emission that causing the global warming. The most promising mitigation strategy is by deploying Carbon Capture and Storage (CCS) technology where mineral carbonation was identified as the safest method for permanent storage and does not require continuous monitoring. Accordingly, National Green Technology was launched in 2009 to support the growth of green technology development in Malaysia as a carbon mitigation strategy. Thus, this paper aims to propose the development of a conceptual eco-design for Low Energy Mechanical Milling (LEMM). The concept was proposed by using the Quality Function Deployment (QFD) tool with combination of sustainability determinants (DFS) namely economic, environmental and social which evaluated using Solidworks 2015 sustainability assessment. The results show the new product targets for LEMM in prior on energy consumption (MJ), selling price (MYR), material cost (MYR), carbon footprint (kg CO2) with weightage of 5.2, 4.2, 3.6 and 3.6 respectively. The implementation of DFS criteria into the QFD promote to reduce material used by 16%, 35% reduction of carbon footprint, 28% less energy consumption, 28% lower air acidification, 77% of water eutrophication declined and increased recyclability by 15%.

  19. Root ABA Accumulation in Long-Term Water-Stressed Plants is Sustained by Hormone Transport from Aerial Organs.

    Science.gov (United States)

    Manzi, Matías; Lado, Joanna; Rodrigo, María Jesús; Zacarías, Lorenzo; Arbona, Vicent; Gómez-Cadenas, Aurelio

    2015-12-01

    The reduced pool of the ABA precursors, β,β-carotenoids, in roots does not account for the substantial increase in ABA content in response to water stress (WS) conditions, suggesting that ABA could be transported from other organs. Basipetal transport was interrupted by stem-girdling, and ABA levels were determined in roots after two cycles of WS induced by transplanting plants to dry perlite. Leaf applications of isotope-labeled ABA and reciprocal grafting of ABA-deficient tomato mutants were used to confirm the involvement of aerial organs on root ABA accumulation. Disruption of basipetal transport reduced ABA accumulation in roots, and this decrease was more severe after two consecutive WS periods. This effect was linked to a sharp decrease in the β,β-carotenoid pool in roots in response to water deficit. Significant levels of isotope-labeled ABA were transported from leaves to roots, mainly in plants subjected to water dehydration. Furthermore, the use of different ABA-deficient tomato mutants in reciprocal grafting combinations with wild-type genotypes confirmed the involvement of aerial organs in the ABA accumulation in roots. In conclusion, accumulation of ABA in roots after long-term WS periods largely relies on the aerial organs, suggesting a reduced ability of the roots to synthesize ABA from carotenoids. Furthermore, plants are able to transport ABA basipetally to sustain high hormone levels in roots. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  20. System-Level Heat Transfer Analysis, Thermal- Mechanical Cyclic Stress Analysis, and Environmental Fatigue Modeling of a Two-Loop Pressurized Water Reactor. A Preliminary Study

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, Subhasish [Argonne National Lab. (ANL), Argonne, IL (United States); Soppet, William [Argonne National Lab. (ANL), Argonne, IL (United States); Majumdar, Saurin [Argonne National Lab. (ANL), Argonne, IL (United States); Natesan, Ken [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-01-03

    This report provides an update on an assessment of environmentally assisted fatigue for light water reactor components under extended service conditions. This report is a deliverable in April 2015 under the work package for environmentally assisted fatigue under DOE's Light Water Reactor Sustainability program. In this report, updates are discussed related to a system level preliminary finite element model of a two-loop pressurized water reactor (PWR). Based on this model, system-level heat transfer analysis and subsequent thermal-mechanical stress analysis were performed for typical design-basis thermal-mechanical fatigue cycles. The in-air fatigue lives of components, such as the hot and cold legs, were estimated on the basis of stress analysis results, ASME in-air fatigue life estimation criteria, and fatigue design curves. Furthermore, environmental correction factors and associated PWR environment fatigue lives for the hot and cold legs were estimated by using estimated stress and strain histories and the approach described in NUREG-6909. The discussed models and results are very preliminary. Further advancement of the discussed model is required for more accurate life prediction of reactor components. This report only presents the work related to finite element modelling activities. However, in between multiple tensile and fatigue tests were conducted. The related experimental results will be presented in the year-end report.

  1. Investigation of Deposit Formation Mechanisms for Engine In-cylinder Combustion and Exhaust Systems Using Quantitative Analysis and Sustainability Study

    Science.gov (United States)

    Ye, Z.; Meng, Q.; Mohamadian, H. P.; Wang, J. T.; Chen, L.; Zhu, L.

    2007-06-01

    The formation of SI engine combustion deposits is a complex phenomenon which depends on various factors of fuel, oil, additives, and engine. The goal of this study is to examine the effects of operating conditions, gasoline, lubricating oil, and additives on deposit formation. Both an experimental investigation and theoretical analysis are conducted on a single cylinder engine. As a result, the impact of deposits on engine performance and exhaust emissions (HC, NO x ) has been indicated. Using samples from a cylinder head and exhaust pipe as well as switching gases via the dual-gas method (N2, O2), the deposit formation mechanism is thoroughly investigated via the thermogravity analysis approach, where the roles of organic, inorganic, and volatile components of fuel, additives, and oil on deposit formation are identified from thermogravity curves. Sustainable feedback control design is then proposed for potential emission control and performance optimization

  2. Shear stress magnitude and duration modulates matrix composition and tensile mechanical properties in engineered cartilaginous tissue.

    Science.gov (United States)

    Gemmiti, Christopher V; Guldberg, Robert E

    2009-11-01

    Cartilage tissue-engineering strategies aim to produce a functional extracellular matrix similar to that of the native tissue. However, none of the myriad approaches taken have successfully generated a construct possessing the structure, composition, and mechanical properties of healthy articular cartilage. One possible approach to modulating the matrix composition and mechanical properties of engineered tissues is through the use of bioreactor-driven mechanical stimulation. In this study, we hypothesized that exposing scaffold-free cartilaginous tissue constructs to 7 days of continuous shear stress at 0.001 or 0.1 Pa would increase collagen deposition and tensile mechanical properties compared to that of static controls. Histologically, type II collagen staining was evident in all construct groups, while a surface layer of type I collagen increased in thickness with increasing shear stress magnitude. The areal fraction of type I collagen was higher in the 0.1-Pa group (25.2 +/- 2.2%) than either the 0.001-Pa (13.6 +/- 3.8%) or the static (7.9 +/- 1.5%) group. Type II collagen content, as assessed by ELISA, was also higher in the 0.1-Pa group (7.5 +/- 2.1%) compared to the 0.001-Pa (3.0 +/- 2.25%) or static groups (3.7 +/- 3.2%). Temporal gene expression analysis showed a flow-induced increase in type I and type II collagen expression within 24 h of exposure. Interestingly, while the 0.1-Pa group showed higher collagen content, this group retained less sulfated glycosaminoglycans in the matrix over time in bioreactor culture. Increases in both tensile Young's modulus and ultimate strength were observed with increasing shear stress, yielding constructs possessing a modulus of nearly 5 MPa and strength of 1.3 MPa. This study demonstrates that shear stress is a potent modulator of both the amount and type of synthesized extracellular matrix constituents in engineered cartilaginous tissue with corresponding effects on mechanical function. Copyright 2009 Wiley

  3. Mechanisms underlying hemodynamic and neuroendocrine stress reactivity at different phases of the menstrual cycle.

    Science.gov (United States)

    Gordon, Jennifer L; Girdler, Susan S

    2014-04-01

    This study examined the association of menstrual cycle phase with stress reactivity as well as the hormonal and neuroendocrine mechanisms contributing to cycle effects. Fifty-seven women underwent a modified Trier Social Stress Test during the early follicular, late follicular, and luteal phases of the menstrual cycle. Greater increases in cardiac index (CI) and greater decreases in vascular resistance index (VRI) during speech were observed in the luteal phase relative to other phases, while greater increases in epinephrine (EPI) was observed during the late follicular and luteal phases compared to the early follicular phase. Luteal phase estradiol predicted luteal EPI reactivity but not CI or VRI reactivity, while luteal phase EPI reactivity predicted luteal phase CI and VRI reactivity. Thus, cycle-related changes in EPI reactivity may be a stronger determinant of cycle effects on hemodynamic reactivity than sex hormones per se. Copyright © 2014 Society for Psychophysiological Research.

  4. The DARTNet Institute: Seeking a Sustainable Support Mechanism for Electronic Data Enabled Research Networks.

    Science.gov (United States)

    Pace, Wilson D; Fox, Chester H; White, Turner; Graham, Deborah; Schilling, Lisa M; West, David R

    2014-01-01

    Clinical data research networks require large investments in infrastructure support to maintain their abilities to extract, transform, and load data from varied data sources, expand electronic data sources and develop learning communities. This paper outlines a sustainable business model of ongoing infrastructure support for clinical data research activities. The DARTNet Institute is a not-for-profit 501(c)(3) organization that serves as a support entity for multiple practice-based research networks. Several clinical data research networks working closely with a professional society began collaborating to support shared goals in 2008. This loose affiliation called itself the "DARTNet Collaborative." In 2011, the DARTNet Institute incorporated as an independent, not-for-profit entity. The business structure allows DARTNet to advocate for all partners without operating its own practice-based research network, serve as a legal voice for activities that overlap multiple partners, share personnel resources through service contracts between partners, and purchase low-cost (nonprofit rate) software. DARTNet's business model relies upon four diverse sources of revenue: (1) DARTNet licenses and provides access to a propriety software system that extracts, transforms, and loads data from all major electronic health records (EHRs) utilized in the United States, and which also provides clinical decision support for research studies; (2) DARTNet operates a recognized, national professional-society-quality improvement registry that enables organizations to fulfill Meaningful Use 2 criteria; (3) DARTNet provides access to data for research activities that are funded by direct research dollars, provided at prices that generate excess revenue; and (4) DARTNet provides access to large primary care datasets for observational studies and pregrant analyses such as for sample size development. The ability of the system to support pragmatic trials will be described. The DARTNet model

  5. An intense elastico-mechanoluminescence material CaZnOS:Mn2+ for sensing and imaging multiple mechanical stresses.

    Science.gov (United States)

    Zhang, Jun-Cheng; Xu, Chao-Nan; Kamimura, Sunao; Terasawa, Yujin; Yamada, Hiroshi; Wang, Xusheng

    2013-06-03

    The elastico-mechanoluminescence (EML) properties of CaZnOS:Mn2+ are investigated. The CaZnOS:Mn2+/epoxy resin composite can simultaneously "feel" (sense) and "see" (image) various types of mechanical stress over a wide energy and frequency range (ultrasonic vibration, impact, friction and compression) as an intense red emission (610 nm) from Mn2+ ions. Further, the accurate linear relation between emission intensity and different stress parameters (intensity, energy and deformation rate) are confirmed. The EML mechanism is explained using a piezoelectrically induced trapped carrier excitation mode. All the results imply that CaZnOS:Mn2+ has potential as a stress probe to sense and image multiple mechanical stresses and decipher the stress intensity distribution.

  6. Chronic restraint stress in rats causes sustained increase in urinary corticosterone excretion without affecting cerebral or systemic oxidatively generated DNA/RNA damage

    DEFF Research Database (Denmark)

    Jorgensen, Anders; Maigaard, Katrine; Wörtwein, Gitta

    2013-01-01

    Increased oxidatively generated damage to nucleic acids (DNA/RNA) may be a common mechanism underlying accelerated aging in psychological stress states and mental disorders. In the present study, we measured the urinary excretion of corticosterone and markers of systemic oxidative stress on nucleic...... of nucleic acid damage from oxidation were affected by stress. In contrast, cerebral DNA repair enzymes exhibited a general trend towards an induction, which was significant for hippocampal Nudt1. The results and their implications for stress sensitivity and resilience are discussed....... acids, 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo), respectively, in rats subjected to chronic restraint stress. To reliably collect 24h urine samples, the full 3-week restraint stress paradigm was performed in metabolism cages. We further determined frontal...

  7. Stress.

    Science.gov (United States)

    Chambers, David W

    2008-01-01

    We all experience stress as a regular, and sometimes damaging and sometimes useful, part of our daily lives. In our normal ups and downs, we have our share of exhaustion, despondency, and outrage--matched with their corresponding positive moods. But burnout and workaholism are different. They are chronic, dysfunctional, self-reinforcing, life-shortening habits. Dentists, nurses, teachers, ministers, social workers, and entertainers are especially susceptible to burnout; not because they are hard-working professionals (they tend to be), but because they are caring perfectionists who share control for the success of what they do with others and perform under the scrutiny of their colleagues (they tend to). Workaholics are also trapped in self-sealing cycles, but the elements are ever-receding visions of control and using constant activity as a barrier against facing reality. This essay explores the symptoms, mechanisms, causes, and successful coping strategies for burnout and workaholism. It also takes a look at the general stress response on the physiological level and at some of the damage American society inflicts on itself.

  8. Human serum albumin and oxidative stress in preeclamptic women and the mechanism of albumin for stress reduction

    Directory of Open Access Journals (Sweden)

    Hiroyuki Kinoshita

    2017-08-01

    Significance: Serum albumin relates to oxidative stress inversely, but to the endothelial function positively, in pregnant women. Human serum albumin appears to reduce oxidative stress via NADPH oxidase inhibition in the human vascular smooth muscle, indicating that the serum level may be a critical determinant of vascular oxidative stress in some human diseases.

  9. Global Gene Expression Analysis Reveals Crosstalk between Response Mechanisms to Cold and Drought Stresses in Cassava Seedlings

    OpenAIRE

    Li, Shuxia; Yu, Xiang; Cheng, Zhihao; Yu, Xiaoling; Ruan, Mengbin; Li, Wenbin; Peng, Ming

    2017-01-01

    Abiotic stress negatively impacts cassava (Manihot esculenta) growth and yield. Several molecular mechanisms of plant response to cold and drought have been identified and described in the literature, however, little is known about the crosstalk of the responses of cassava to these two stresses. To elucidate this question, transcriptome analysis of cassava seedlings under cold or PEG-simulated drought stress treatment was performed. Our results showed that 6103 and 7462 transcripts were signi...

  10. Interactive effects of spectral shading and mechanical stress on the expression and costs of shade avoidance.

    Science.gov (United States)

    Anten, Niels P R; von Wettberg, Eric J; Pawlowski, Marcin; Huber, Heidrun

    2009-02-01

    The interacting effects of different environmental cues in determining a plant's phenotype and performance are poorly understood aspects of phenotypic plasticity. We examined the interacting effects of shading and mechanical stress (MS) on growth, reproduction, and mechanical stability. We subjected 10 grassland genotypes and 10 forest genotypes of Impatiens capensis to two levels of spectral shading and two levels of MS. Shade induced the production of taller, thinner internodes, but this response was inhibited by MS. This interactive effect was stronger in the grassland genotypes than in the forest genotypes, indicating that shade avoidance can be suppressed by MS and that the degree of this suppression differs between habitats. Among genotypes, greater plasticity in shade-induced internode elongation resulted in a larger reduction in the ability of plants to carry their own weight. This suggests that the occurrence of mechanical constraints may strongly contribute to the selection against shade-induced elongation responses in forest understory genotypes. Our results show that combined responses to different environmental cues can result in a fine-tuning of phenotypic expression by plants by maintaining the potential to strongly respond to single environmental cues but also by preventing potential future costs resulting from poor adaptation to other stresses.

  11. Effect of mean stress and amplitude stress on mechanical stress-strain response of chopped strand mat (CSM) composite under cyclic load

    Science.gov (United States)

    Fatinah, T. S.; Basaruddin, K. S.; Rahman, A. S. Abd; Majid, M. S. Abdul

    2017-09-01

    This paper presents a study on the effect of mean stress and amplitude stress on chopped strand mat (CSM) composite material under cyclic load. Specimen of CSM was prepared by hand lay-up process. The uniaxial tensile test was conducted to obtain the stress strain curve of CSM. In order to investigate the effect of mean and amplitude stress on CSM, a simulation using ANSYS workbench was employed. Ten loading cases for varying amplitude stress with constant mean stress and another ten cases of varying mean stress with constant amplitude stress were performed. The results suggest that the mean and amplitude stress contribute to material failure under cyclic load. Failure of CSM more sensitive for the case with varying mean stress compared to varying amplitude stress.

  12. Regional Stress Field in the Maghreb Region From an Updated Focal Mechanism Catalog (1954-2014)

    Science.gov (United States)

    Lamara, Samir; Friederich, Wolfgang

    2015-04-01

    In order to investigate the regional stress field in the Maghreb region we construct a focal mechanism catalog for earthquakes that occurred from 1954 to 2014. To this intent, all available moment tensor solutions of past earthquakes obtained from different sources were checked, compared and corrected. Furthermore, the focal solutions of all recent earthquakes with magnitude down to 4 and for which data is available were calculated using a new method based on waveform fitting of observed seismograms and synthetics calculated for a range of fault angles and hypocenter depths. Observed seismograms of all stations for a given earthquake were thus collected, processed and subject to a rigorous quality control according to the corresponding signal-to-noise ratio. An average 1-D earth model for the Maghreb-western Mediterranean region was also constructed to calculate synthetics. The misfits between these observed seismograms and a set of synthetics calculated for every value of fault angles (strike, dip and rake) and hypocenter depths were calculated after respectively, a phase fitting obtained by shifting the seismograms to the best cross-correlation between data and synthetics, and amplitudes scaling. The best configuration of fault angles and hypocenter depths was then selected according to the smallest average misfit over all stations. If a systematic time shift was noticeable for all stations or most of them, an additional relocation step was done to obtain the most accurate earthquake's epicenter. Most of the earthquakes included in the catalog define several spatial clusters for which the assumption of homogeneous stress can be fulfilled. Hence, a stress inversion for each cluster was performed and a stress ratio indicating the dominance of compressional or tensional stresses as well as the directions and dips of the tensional, intermediate and compressional axis were obtained.

  13. Stress Field in Brazil with Focal Mechanism: Regional and Local Patterns

    Science.gov (United States)

    Dias, F.; Assumpcao, M.

    2013-05-01

    The knowledge of stress field is fundamental not only to understand driving forces and plate deformation but also in the study of intraplate seismicity. The stress field in Brazil has been determined mainly using focal mechanisms and a few breakout data and in-situ measurements. However the stress field still is poorly known in Brazil. The focal mechanisms of recent earthquakes (magnitude lower than 5 mb) were studied using waveform modeling. We stacked the record of several teleseismic stations ( delta > 30°) stacked groups of stations separated according to distance and azimuth. Every record was visually inspected and those with a good signal/noise ratio (SNR) were grouped in windows of ten degrees distance and stacked. The teleseismic P-wave of the stacked signals was modeled using the hudson96 program of Herrmann seismology package (Herrmann, 2002) and the consistency of focal mechanism with the first-motion was checked. Some events in central Brazil were recorded by closer stations (~ 1000 km) and the moment tensor was determined with the ISOLA code (Sokos & Zahradnik, 2008). With the focal mechanisms available in literature and those obtained in this work, we were able to identify some patterns: the central region shows a purely compressional pattern (E-W SHmax), which is predicted by regional theoretical models (Richardson & Coblentz, 1996 and the TD0 model of Lithgow & Bertelloni, 2004). Meanwhile in the Amazon we find an indication of SHmax oriented in the SE-NW direction, probably caused by the Caribbean plate interaction (Meijer, 1995). In northern coastal region, the compression rotates following the coastline, which indicates an important local component related to spreading effects at the continental/oceanic transition (Assumpção, 1998) and flexural stresses caused by sedimentary load in Amazon Fan. We determine the focal mechanism of several events in Brazil using different techniques according to the available data. The major difficulty is to

  14. Study of Tectonic Tremor in Depth: Triggering Stress Observation and Model of the Triggering Mechanism

    Science.gov (United States)

    Wang, Tien-Huei

    Non-volcanic tremor (NVT) has been discovered in recent years due to advances in seismic instruments and increased density of seismic networks. The NVT is a special kind of seismic signal indicative of the physical conditions and the failure mechanism on the source on the fault where NVT occurs. The detection methods used and the sensitivity of them relies on the density, distance and instrumentation of the station network available. How accurately the tremor is identified in different regions varies greatly among different studies. Therefore, there has not been study that rigorously documents tectonic tremors in different regions under limited methods and data. Meanwhile, many incidences of NVTs are observed during or after small but significant strain change induced by teleseismic, regional or local earthquake. The understanding of the triggering mechanisms critical for tremor remains unclear. In addition, characteristics of the triggering of NVT in different regions are rarely compared because of the short time frame after the discovery of the triggered NVTs. We first explore tectonic tremor based on observations to learn about its triggering, frequency of occurrence, location and spectral characteristics. Then, we numerically model the triggering of instability on the estimated tremor-source, under assumptions fine-tuned according to previous studies (Thomas et al., 2009; Miyazawa et al., 2005; Hill, 2008; Ito, 2009; Rubinstein et al., 2007; Peng and Chao, 2008). The onset of the slip reveals that how and when the external loading triggers tremor. It also holds the information to the background stress conditions under which tremor source starts with. We observe and detect tremor in two regions: Anza and Cholame, along San Jacinto Fault (SJF) and San Andreas Fault (SAF) respectively. These two sections of the faults, relative to general fault zone on which general earthquakes occur, are considered transition zones where slip of slow rates occurs. Slip events

  15. Improved clean development mechanism and joint implementation to promote holistic sustainable development - an integrated policy and methodology for international energy collaboration

    Energy Technology Data Exchange (ETDEWEB)

    Kua Harn Wei

    2007-07-01

    The current Clean Development Mechanism/Joint Implementation framework does not emphasize on wholistic sustainability of energy projects. The Golden Standard was a good example of how this framework can be fine-tuned. However, it does not explicitly incentivize the adoption of the sustainability standards it outlines. A 4-element integrated policy strategy is proposed. A Sustainability Assessment Matrix is constructed to evaluate project proposals' sustainability performance. The Probational Sustainability Performance Demand requires continual monitoring of this performance of approved projects throughout a designated probation period. The involved countries will be awarded Sustainability Credits (measured with the matrix) in installments according to their performance within this period. The Probational Emission Reduction Demand requires investing countries to meet moderated emission reduction targets in order for them to claim the certified emission reductions/ emission reduction credits and their share of Sustainability Credits. These credits are converted into Sustainability Assistance Funds, which can be channeled back to finance either the approved projects or independent renewable energy projects in the involved countries. The MIT Energy Cost Model is used to estimate the required amount and identify the forms of such assistance package. Finally, an integrated policymaking framework is suggested to execute and monitor these interconnected policy elements. (auth)

  16. Hot Press as a Sustainable Direct Recycling Technique of Aluminium: Mechanical Properties and Surface Integrity

    Science.gov (United States)

    Lajis, Mohd Amri; Ahmad, Azlan

    2017-01-01

    Meltless recycling technique has been utilized to overcome the lack of primary resources, focusing on reducing the usage of energy and materials. Hot press was proposed as a novel direct recycling technique which results in astoundingly low energy usage in contrast with conventional recycling. The aim of this study is to prove the technical feasibility of this approach by characterizing the recycled samples. For this purpose, AA6061 aluminium chips were recycled by utilizing hot press process under various operating temperature (Ts = 430, 480, and 530 °C) and holding times (ts = 60, 90, and 120 min). The maximum mechanical properties of recycled chip are Ultimate tensile strength (UTS) = 266.78 MPa, Elongation to failure (ETF) = 16.129%, while, for surface integrity of the chips, the calculated microhardness is 81.744 HV, exhibited at Ts = 530 °C and ts = 120 min. It is comparable to theoretical AA6061 T4-temper where maximum UTS and microhardness is increased up to 9.27% and 20.48%, respectively. As the desired mechanical properties of forgings can only be obtained by means of a final heat treatment, T5-temper, aging after forging process was employed. Heat treated recycled billet AA6061 (T5-temper) are considered comparable with as-received AA6061 T6, where the value of microhardness (98.649 HV) at 175 °C and 120 min of aging condition was revealed to be greater than 3.18%. Although it is quite early to put a base mainly on the observations in experimental settings, the potential for significant improvement offered by the direct recycling methods for production aluminium scrap can be clearly demonstrated. This overtures perspectives for industrial development of solid state recycling processes as environmentally benign alternatives of current melting based practices. PMID:28771207

  17. Piezoelectric Pre-Stressed Bending Mechanism for Impact-Driven Energy Harvester

    Science.gov (United States)

    Abdal, A. M.; Leong, K. S.

    2017-06-01

    This paper experimentally demonstrates and evaluates a piezoelectric power generator bending mechanism based on pre-stressed condition whereby the piezoelectric transducer being bended and remained in the stressed condition before applying a force on the piezoelectric bending structure, which increase the stress on the piezoelectric surface and hence increase the generated electrical charges. An impact force is being exerted onto bending the piezoelectric beam and hence generating electrical power across an external resistive load. The proposed bending mechanism prototype has been manufactured by employing 3D printer technology in order to conduct the evaluation. A free fall test has been conducted as the evaluation method with varying force using a series of different masses and different fall heights. A rectangular piezoelectric harvester beam with the size of 32mm in width, 70mm in length, and 0.55mm in thickness is used to demonstrate the experiment. It can be seen from the experiment that the instantaneous peak to peak AC volt output measured at open-circuit is increasing and saturated at about of 70V when an impact force of about 80N is being applied. It is also found that a maximum power of about 53mW is generated at an impact force of 50N when it is connected to an external resistive load of 0.7KΩ. The reported mechanism is a promising candidate in the application of energy harvesting for powering various wireless sensor nodes (WSN) which is the core of Internet of Things (IoT).

  18. Mechanical Stress Changes the Complex Interplay Between HO-1, Inflammation and Fibrosis, During Excisional Wound Repair.

    Science.gov (United States)

    Cremers, Niels A J; Suttorp, Maarten; Gerritsen, Marlous M; Wong, Ronald J; van Run-van Breda, Coby; van Dam, Gooitzen M; Brouwer, Katrien M; Kuijpers-Jagtman, Anne Marie; Carels, Carine E L; Lundvig, Ditte M S; Wagener, Frank A D T G

    2015-01-01

    Mechanical stress following surgery or injury can promote pathological wound healing and fibrosis, and lead to functional loss and esthetic problems. Splinted excisional wounds can be used as a model for inducing mechanical stress. The cytoprotective enzyme heme oxygenase-1 (HO-1) is thought to orchestrate the defense against inflammatory and oxidative insults that drive fibrosis. Here, we investigated the activation of the HO-1 system in a splinted and non-splinted full-thickness excisional wound model using HO-1-luc transgenic mice. Effects of splinting on wound closure, HO-1 promoter activity, and markers of inflammation and fibrosis were assessed. After seven days, splinted wounds were more than three times larger than non-splinted wounds, demonstrating a delay in wound closure. HO-1 promoter activity rapidly decreased following removal of the (epi)dermis, but was induced in both splinted and non-splinted wounds during skin repair. Splinting induced more HO-1 gene expression in 7-day wounds; however, HO-1 protein expression remained lower in the epidermis, likely due to lower numbers of keratinocytes in the re-epithelialization tissue. Higher numbers of F4/80-positive macrophages, αSMA-positive myofibroblasts, and increased levels of the inflammatory genes IL-1β, TNF-α, and COX-2 were present in 7-day splinted wounds. Surprisingly, mRNA expression of newly formed collagen (type III) was lower in 7-day wounds after splinting, whereas, VEGF and MMP-9 were increased. In summary, these data demonstrate that splinting delays cutaneous wound closure and HO-1 protein induction. The pro-inflammatory environment following splinting may facilitate higher myofibroblast numbers and increase the risk of fibrosis and scar formation. Therefore, inducing HO-1 activity against mechanical stress-induced inflammation and fibrosis may be an interesting strategy to prevent negative effects of surgery on growth and function in patients with orofacial clefts or in patients with

  19. Mechanical massage and mental training programmes affect employees' anxiety, stress susceptibility and detachment-a randomised explorative pilot study

    National Research Council Canada - National Science Library

    Muller, Jasmin; Handlin, Linda; Harlén, Mikael; Lindmark, Ulrika; Ekström, Anette

    2015-01-01

    .... One not yet evidence-based preventive method designed to help employees keep healthy and be less stressed is an armchair with built-in mechanical massage and mental training programmes, This study...

  20. Which Factors Can Protect Against Range Stress in Everyday Usage of Battery Electric Vehicles? Toward Enhancing Sustainability of Electric Mobility Systems.

    Science.gov (United States)

    Franke, Thomas; Rauh, Nadine; Günther, Madlen; Trantow, Maria; Krems, Josef F

    2016-02-01

    The objective of the present research was to advance understanding of factors that can protect against range anxiety, specifically range stress in everyday usage of battery electric vehicles (BEVs). Range anxiety is a major barrier to the broad adoption of sustainable electric mobility systems. To develop strategies aimed at overcoming range anxiety, a clear understanding of this phenomenon and influencing factors is needed. We examined range anxiety in the form of everyday range stress (ERS) in a field study setting. Seventy-two customers leased a BEV for 3 months. The field study was specifically designed to enable examination of factors that can contribute to lower ERS. In particular, study design and sample recruitment were targeted at generating vehicle usage profiles that would lead to relatively frequent experience of situations requiring active management of range resources and thereby potentially leading to experienced range stress. Less frequent encounter with critical range situations, higher practical experience, subjective range competence, tolerance of low range, and experienced trustworthiness of the range estimation system were related to lower ERS. Moreover, range stress was found to be related to range satisfaction and BEV acceptance. The results underline the importance of the human factors perspective to overcome range anxiety and enhance sustainability of electric mobility systems. Trustworthiness should be employed as a key benchmark variable in the design of range estimation systems, and assistance systems should target increasing drivers' adaptive capacity (i.e., resilience) to cope with critical range situations. © 2015, Human Factors and Ergonomics Society.

  1. Three-dimensional elastic--plastic stress and strain analyses for fracture mechanics: complex geometries

    Energy Technology Data Exchange (ETDEWEB)

    Bellucci, H.J.

    1975-11-01

    The report describes the continuation of research into capability for three-dimensional elastic-plastic stress and strain analysis for fracture mechanics. A computer program, MARC-3D, has been completed and was used to analyze a cylindrical pressure vessel with a nozzle insert. A method for generating crack tip elements was developed and a model was created for a cylindrical pressure vessel with a nozzle and an imbedded flaw at the inside nozzle corner. The MARC-3D program was again used to analyze this flawed model. Documentation for the use of the MARC-3D computer program has been included as an appendix.

  2. Mechanisms of Mycotoxin-induced Dermal Toxicity and Tumorigenesis Through Oxidative Stress-related Pathways.

    Science.gov (United States)

    Doi, Kunio; Uetsuka, Koji

    2014-04-01

    Among the many mycotoxins, T-2 toxin, citrinin (CTN), patulin (PAT), aflatoxin B1 (AFB1) and ochratoxin A (OTA) are known to have the potential to induce dermal toxicity and/or tumorigenesis in rodent models. T-2 toxin, CTN, PAT and OTA induce apoptosis in mouse or rat skin. PAT, AFB1 and OTA have tumor initiating properties, and OTA is also a tumor promoter in mouse skin. This paper reviews the molecular mechanisms of dermal toxicity and tumorigenesis induced in rodent models by these mycotoxins especially from the viewpoint of oxidative stress-mediated pathways.

  3. Simulation of Weld Mechanical Behavior to Include Welding-Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes

    Science.gov (United States)

    2015-11-01

    2011, Vol. 88, pg. 45-56. 7. Z.H. Guo, X.Y. Ou, G.W. Shuai, and Y.H. Chen, Numerical Simulation of Temperature Field for TIG Welding of Aluminum Alloy...Memorandum Simulation of Weld Mechanical Behavior to Include Welding -Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes... Weld Mechanical Behavior to Include Welding -Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes by Charles R. Fisher

  4. Simulation of Weld Mechanical Behavior to Include Welding Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes

    Science.gov (United States)

    2015-11-01

    2011, Vol. 88, pg. 45-56. 7. Z.H. Guo, X.Y. Ou, G.W. Shuai, and Y.H. Chen, Numerical Simulation of Temperature Field for TIG Welding of Aluminum Alloy...Memorandum Simulation of Weld Mechanical Behavior to Include Welding -Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes... Weld Mechanical Behavior to Include Welding -Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes by Charles R. Fisher

  5. Admixtures in Cement-Matrix Composites for Mechanical Reinforcement, Sustainability, and Smart Features.

    Science.gov (United States)

    Bastos, Guillermo; Patiño-Barbeito, Faustino; Patiño-Cambeiro, Faustino; Armesto, Julia

    2016-11-30

    For more than a century, several inclusions have been mixed with Portland cement-nowadays the most-consumed construction material worldwide-to improve both the strength and durability required for construction. The present paper describes the different families of inclusions that can be combined with cement matrix and reviews the achievements reported to date regarding mechanical performance, as well as two other innovative functionalities of growing importance: reducing the high carbon footprint of Portland cement, and obtaining new smart features. Nanomaterials stand out in the production of such advanced features, allowing the construction of smart or multi-functional structures by means of thermal- and strain-sensing, and photocatalytic properties. The first self-cleaning concretes (photocatalytic) have reached the markets. In this sense, it is expected that smart concretes will be commercialized to address specialized needs in construction and architecture. Conversely, other inclusions that enhance strength or reduce the environmental impact remain in the research stage, in spite of the promising results reported in these issues. Despite the fact that such functionalities are especially profitable in the case of massive cement consumption, the shift from the deeply established Portland cement to green cements still has to overcome economic, institutional, and technical barriers.

  6. Sustainable and smart keratin hydrogel with pH-sensitive swelling and enhanced mechanical properties.

    Science.gov (United States)

    Peralta Ramos, María Luz; González, Joaquín Antonio; Fabian, Lucas; Pérez, Claudio Javier; Villanueva, María Emilia; Copello, Guillermo Javier

    2017-09-01

    Protein based hydrogels are a very interesting type of biomaterials with many probed strengths related to their source and chemical structure. Biocompatibility and biodegradability are accompanied by affordability when it comes to low cost sources. The main keratin source is agroindustrial waste, such as feathers, horns, hooves, hair and wool. Thus, the main cost of keratin hydrogels derives from their processing. Here is presented a new strategy for the obtaining of a keratin hydrogel with enhanced mechanical properties using low cost reagents. This keratin hydrogel is stiff enough to allow handling without special cares and also presenting a reversible pH-responsive behavior. The minimum swelling is observed at low pH due to a collapsed and disordered protein network with water tightly adsorbed to the hydrophilic sites. The swelling rises significantly above pH6 and the maximum swelling appears above pH8 where an expanded network allows water to enter to the pores. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Sustainable power generation in microbial fuel cells using bicarbonate buffer and proton transfer mechanisms.

    Science.gov (United States)

    Fan, Yanzhen; Hu, Hongqiang; Liu, Hong

    2007-12-01

    Phosphate buffer solution has been commonly used in MFC studiesto maintain a suitable pH for electricity-generating bacteria and/or to increase the solution conductivity. However, addition of a high concentration of phosphate buffer in MFCs could be expensive, especially for wastewater treatment. In this study, the performances of MFCs with cloth electrode assemblies (CEA) were evaluated using bicarbonate buffer solutions. A maximum power density of 1550 W/m3 (2770 mW/ m2) was obtained at a current density of 0.99 mA/cm2 using a pH 9 bicarbonate buffer solution. Such a power density was 38.6% higher than that using a pH 7 phosphate buffer at the same concentration of 0.2 M. Based on the quantitative comparison of free proton transfer rates, diffusion rates of pH buffer species, and the current generated, a facilitated proton transfer mechanism was proposed for MFCs in the presence of the pH buffers. The excellent performance of MFCs using bicarbonate as pH buffer and proton carrier indicates that bicarbonate buffer could be served as a low-cost and effective pH buffer for practical applications, especially for wastewater treatment.

  8. Direct effect of infliximab on intestinal mucosa sustains mucosal healing: exploring new mechanisms of action.

    Science.gov (United States)

    Petito, Valentina; Lopetuso, Loris Riccardo; Arena, Vincenzo; Stigliano, Egidio; Boninsegna, Alma; Bibbò, Stefano; Poscia, Andrea; Alfieri, Sergio; Rosa, Fausto; Amato, Arianna; Cammarota, Giovanni; Papa, Alfredo; Sgambato, Alessandro; Gasbarrini, Antonio; Scaldaferri, Franco

    2016-04-01

    Infliximab is effective in inflammatory bowel disease through several mechanisms, possibly acting at the mucosal level. To assess the role of infliximab on intestinal mucosa and whether it contributes to mucosal healing. Human colonic mucosal biopsies were incubated with or without infliximab. Cultured biopsies were evaluated for histological staining, CD68, CD3, E-cadherin and phospho-extracellular signal-regulated kinases (ERK) expression, and apoptosis. A scratch assay and MTT assay were performed with Caco2 cells in the presence of infliximab and/or tumour necrosis factor (TNF)-α or treated with supernatants obtained from human peripheral blood mononuclear cells or human intestinal fibroblasts treated with TNF-α and infliximab alone or in association. Infliximab-treated biopsies displayed a better histological appearance, reduced inflammation with an increase of E-cadherin, phospho-ERK and apoptosis. Supernatants showed lower TNF-α, IL-17, IL-6 and IL-8 concentration, with an increase in fibroblast-growth-factor. Motility at scratch assay and proliferation at MTT assay of Caco2 cells displayed differential modulation by TNF-α and infliximab, directly or through supernatants of human intestinal fibroblasts and human peripheral blood mononuclear cells exposed to them. Infliximab contributes to the mucosal healing process by acting directly at an intestinal mucosal level; infliximab indirectly affects epithelial cell migration and proliferation by acting on both fibroblasts and leukocytes. Copyright © 2015 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

  9. Integrin β1 Gene Therapy Enhances in Vitro Creation of Tissue-Engineered Cartilage Under Periodic Mechanical Stress

    Directory of Open Access Journals (Sweden)

    Wenwei Liang

    2015-10-01

    Full Text Available Background/Aims: Periodic mechanical stress activates integrin β1-initiated signal pathways to promote chondrocyte proliferation and matrix synthesis. Integrin β1 overexpression has been demonstrated to play important roles in improving the activities and functions of several non-chondrocytic cell types. Therefore, in the current study, we evaluated the effects of integrin β1 up-regulation on periodic mechanical stress-induced chondrocyte proliferation, matrix synthesis and ERK1/2 phosphorylation in chondrocyte monolayer culture, and evaluated the quality of tissue-engineered cartilage constructed in vitro under periodic mechanical stress combined with integrin β1 up-regulation. Methods and Results: Our results revealed that under periodic mechanical stress, pre-treatment with integrin β1-wild type vector significantly enhanced chondrocyte proliferation and matrix synthesis and promoted ERK1/2 phosphorylation in comparison to mock transfectants. Furthermore, when chondrocytes were seeded in PLGA scaffolds, more accumulated GAG and type II collagen tissue were detected after Lv-integrin β1 transfection compared with sham controls exposed to periodic mechanical stress. In contrast, in the Lv-shRNA-integrin β1 group, the opposite results were observed. Conclusion: Our findings collectively suggest that in addition to periodic mechanical stress, integrin β1 up-regulation in chondrocytes could further improve the quality of tissue-engineered cartilage.

  10. Mechanical properties and environmental stress cracking resistance of rubber toughened polyester/kenaf composite

    Directory of Open Access Journals (Sweden)

    2010-02-01

    Full Text Available In this study rubber-toughened polyester-kenaf fibre composites were prepared by adding various percentages of kenaf fibre in unsaturated polyester resin and subsequently cross linked using a mixture of organic peroxide methyl ethyl ketone and cobalt octanoate. Three percent (3% of liquid natural rubber (LNR were added as a toughening agent. The mechanical properties of the composites were evaluated by impact and flexural testing. Environmental stress cracking resistance (ESCR of polyester-kenaf composite in acid and base medium was also studied. It was found that the addition of LNR increased impact strength by about 66% and flexural strength by 70%. Measurement of ESCR shows that the composite has the fastest diffusion rate in acid medium, followed by that in base medium and then without medium. Bonding mechanisms were assessed by scanning electron microscope and FTIR analysis.

  11. Ferroelectric behavior of a lead titanate nanosphere due to depolarization fields and mechanical stresses

    Energy Technology Data Exchange (ETDEWEB)

    Andrade Landeta, J.; Lascano, I.

    2017-07-01

    A theorical model has been developed based on the theory of Ginzburg-Landau-Devonshire to study and predict the effects the decreasing of size particle in a nanosphere of PbTiO3 subjected to the action of depolarization fields and mechanical stress. It was considered that the nanosphere is surrounded by a layer of space charges on its surface, and containing 180° domains generated by minimizing free energy of depolarization. Energy density of depolarization, wall domain and electro-elastic energy have been incorporated into the free energy of the theory Ginzburg-Landau-Devonshire. Free energy minimization was performed to determine the spontaneous polarization and transition temperature system. These results show that the transition temperature for nanosphere is substantially smaller than the corresponding bulk material. Also, it has been obtained that the stability of the ferroelectric phase of nanosphere is favored for configurations with a large number of 180° domains, with the decreasing of thickness space charge layer, and the application of tensile stress and decreases with compressive stress. (Author)

  12. Oxidative Stress in Hypoxic-Ischemic Encephalopathy: Molecular Mechanisms and Therapeutic Strategies

    Directory of Open Access Journals (Sweden)

    Mingyi Zhao

    2016-12-01

    Full Text Available Hypoxic-ischemic encephalopathy (HIE is one of the leading causes of morbidity and mortality in neonates. Because of high concentrations of sensitive immature cells, metal-catalyzed free radicals, non-saturated fatty acids, and low concentrations of antioxidant enzymes, the brain requires high levels of oxygen supply and is, thus, extremely sensitive to hypoxia. Strong evidence indicates that oxidative stress plays an important role in pathogenesis and progression. Following hypoxia and ischemia, reactive oxygen species (ROS production rapidly increases and overwhelms antioxidant defenses. A large excess of ROS will directly modify or degenerate cellular macromolecules, such as membranes, proteins, lipids, and DNA, and lead to a cascading inflammatory response, and protease secretion. These derivatives are involved in a complex interplay of multiple pathways (e.g., inflammation, apoptosis, autophagy, and necrosis which finally lead to brain injury. In this review, we highlight the molecular mechanism for oxidative stress in HIE, summarize current research on therapeutic strategies utilized in combating oxidative stress, and try to explore novel potential clinical approaches.

  13. Tuning of redox regulatory mechanisms, reactive oxygen species and redox homeostasis under salinity stress

    Directory of Open Access Journals (Sweden)

    Hossain eSazzad

    2016-05-01

    Full Text Available Soil salinity is a crucial environmental constraint which limits biomass production at many sites on a global scale. Saline growth conditions cause osmotic and ionic imbalances, oxidative stress and perturb metabolism, e.g. the photosynthetic electron flow. The plant ability to tolerate salinity is determined by multiple biochemical and physiological mechanisms protecting cell functions, in particular by regulating proper water relations and maintaining ion homeostasis. Redox homeostasis is a fundamental cell property. Its regulation includes control of reactive oxygen species (ROS generation, sensing deviation from and readjustment of the cellular redox state. All these redox related functions have been recognized as decisive factors in salinity acclimation and adaptation. This review focuses on the core response of plants to overcome the challenges of salinity stress through regulation of ROS generation and detoxification systems and to maintain redox homeostasis. Emphasis is given to the role of NADH oxidase (RBOH, alternative oxidase (AOX, the plastid terminal oxidase (PTOX and the malate valve with the malate dehydrogenase isoforms under salt stress. Overwhelming evidence assigns an essential auxiliary function of ROS and redox homeostasis to salinity acclimation of plants.

  14. HCV Core Protein Uses Multiple Mechanisms to Induce Oxidative Stress in Human Hepatoma Huh7 Cells

    Science.gov (United States)

    Ivanov, Alexander V.; Smirnova, Olga A.; Petrushanko, Irina Y.; Ivanova, Olga N.; Karpenko, Inna L.; Alekseeva, Ekaterina; Sominskaya, Irina; Makarov, Alexander A.; Bartosch, Birke; Kochetkov, Sergey N.; Isaguliants, Maria G.

    2015-01-01

    Hepatitis C virus (HCV) infection is accompanied by the induction of oxidative stress, mediated by several virus proteins, the most prominent being the nucleocapsid protein (HCV core). Here, using the truncated forms of HCV core, we have delineated several mechanisms by which it induces the oxidative stress. The N-terminal 36 amino acids of HCV core induced TGFβ1-dependent expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidases 1 and 4, both of which independently contributed to the production of reactive oxygen species (ROS). The same fragment also induced the expression of cyclo-oxygenase 2, which, however, made no input into ROS production. Amino acids 37–191 of HCV core up-regulated the transcription of a ROS generating enzyme cytochrome P450 2E1. Furthermore, the same fragment induced the expression of endoplasmic reticulum oxidoreductin 1α. The latter triggered efflux of Ca2+ from ER to mitochondria via mitochondrial Ca2+ uniporter, leading to generation of superoxide anions, and possibly also H2O2. Suppression of any of these pathways in cells expressing the full-length core protein led to a partial inhibition of ROS production. Thus, HCV core causes oxidative stress via several independent pathways, each mediated by a distinct region of the protein. PMID:26035647

  15. Polyphenol Stilbenes: Molecular Mechanisms of Defence against Oxidative Stress and Aging-Related Diseases

    Directory of Open Access Journals (Sweden)

    Mika Reinisalo

    2015-01-01

    Full Text Available Numerous studies have highlighted the key roles of oxidative stress and inflammation in aging-related diseases such as obesity, type 2 diabetes, age-related macular degeneration (AMD, and Alzheimer’s disease (AD. In aging cells, the natural antioxidant capacity decreases and the overall efficiency of reparative systems against cell damage becomes impaired. There is convincing data that stilbene compounds, a diverse group of natural defence phenolics, abundant in grapes, berries, and conifer bark waste, may confer a protective effect against aging-related diseases. This review highlights recent data helping to clarify the molecular mechanisms involved in the stilbene-mediated protection against oxidative stress. The impact of stilbenes on the nuclear factor-erythroid-2-related factor-2 (Nrf2 mediated cellular defence against oxidative stress as well as the potential roles of SQSTM1/p62 protein in Nrf2/Keap1 signaling and autophagy will be summarized. The therapeutic potential of stilbene compounds against the most common aging-related diseases is discussed.

  16. Skin aging and oxidative stress: Equol's anti-aging effects via biochemical and molecular mechanisms.

    Science.gov (United States)

    Lephart, Edwin D

    2016-11-01

    Oxygen in biology is essential for life. It comes at a cost during normal cellular function, where reactive oxygen species (ROS) are generated by oxidative metabolism. Human skin exposed to solar ultra-violet radiation (UVR) dramatically increases ROS production/oxidative stress. It is important to understand the characteristics of human skin and how chronological (intrinsic) aging and photo-aging (extrinsic aging) occur via the impact of ROS production by cascade signaling pathways. The goal is to oppose or neutralize ROS insults to maintain good dermal health. Botanicals, as active ingredients, represent one of the largest categories used in dermatology and cosmeceuticals to combat skin aging. An emerging botanical is equol, a polyphenolic/isoflavonoid molecule found in plants and food products and via gastrointestinal metabolism from precursor compounds. Introductory sections cover oxygen, free radicals (ROS), oxidative stress, antioxidants, human skin aging, cellular/molecular ROS events in skin, steroid enzymes/receptors/hormonal actions and genetic factors in aging skin. The main focus of this review covers the characteristics of equol (phytoestrogenic, antioxidant and enhancement of extracellular matrix properties) to reduce skin aging along with its anti-aging skin influences via reducing oxidative stress cascade events by a variety of biochemical/molecular actions and mechanisms to enhance human dermal health. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Effects of mechanical ventilation with different tidal volume on oxidative stress and antioxidant in lung.

    Science.gov (United States)

    Sun, Zhen-Tao; Yang, Chun-Yao; Miao, Li-Jun; Zhang, Shan-Feng; Han, Xue-Ping; Ren, Su-En; Sun, Xue-Qing; Cao, Ya-Nan

    2015-06-01

    The aim of this study was to investigate the changes in oxidative stress and antioxidants in lung tissue under different tidal volume ventilation conditions. Forty-eight male Wistar rats were randomized into four groups, namely, group C, the control group, which was not ventilated, and groups C1, C2 and C3, the treatment groups, which were ventilated for 2 h with tidal volumes of 8, 30 and 42 ml/kg, respectively. The right middle lobe was assayed for malondialdehyde (MDA), the right posterior lobe was assayed using Western blotting for Nrf2, GCLm and SrX1 and the left lobe was assayed for Nrf2, GCLm and SrX1 mRNA. The MDA levels were increased in the three treatment groups, with MDA levels highest in group C3 and lowest in group C1 (C3 > C2 > C1) (all P C2 > C1) (all P 0.05). A Western blot analysis showed that Nrf2, GCLm and SrX1 expression was highest in group C3 and lowest in group C1 (C3 > C2 > C1) (all P 0.05). Oxidative stress and antioxidant enzyme levels in the lungs of rats were positively associated with the tidal volumes of mechanical ventilation, suggesting that higher tidal volumes cause more severe oxidative stress and increased antioxidant responses.

  18. Polyphenol Stilbenes: Molecular Mechanisms of Defence against Oxidative Stress and Aging-Related Diseases.

    Science.gov (United States)

    Reinisalo, Mika; Kårlund, Anna; Koskela, Ali; Kaarniranta, Kai; Karjalainen, Reijo O

    2015-01-01

    Numerous studies have highlighted the key roles of oxidative stress and inflammation in aging-related diseases such as obesity, type 2 diabetes, age-related macular degeneration (AMD), and Alzheimer's disease (AD). In aging cells, the natural antioxidant capacity decreases and the overall efficiency of reparative systems against cell damage becomes impaired. There is convincing data that stilbene compounds, a diverse group of natural defence phenolics, abundant in grapes, berries, and conifer bark waste, may confer a protective effect against aging-related diseases. This review highlights recent data helping to clarify the molecular mechanisms involved in the stilbene-mediated protection against oxidative stress. The impact of stilbenes on the nuclear factor-erythroid-2-related factor-2 (Nrf2) mediated cellular defence against oxidative stress as well as the potential roles of SQSTM1/p62 protein in Nrf2/Keap1 signaling and autophagy will be summarized. The therapeutic potential of stilbene compounds against the most common aging-related diseases is discussed.

  19. Proteomic Characterization of Armillaria mellea Reveals Oxidative Stress Response Mechanisms and Altered Secondary Metabolism Profiles

    Directory of Open Access Journals (Sweden)

    Cassandra Collins

    2017-09-01

    Full Text Available Armillaria mellea is a major plant pathogen. Yet, the strategies the organism uses to infect susceptible species, degrade lignocellulose and other plant material and protect itself against plant defences and its own glycodegradative arsenal are largely unknown. Here, we use a combination of gel and MS-based proteomics to profile A. mellea under conditions of oxidative stress and changes in growth matrix. 2-DE and LC-MS/MS were used to investigate the response of A. mellea to H2O2 and menadione/FeCl3 exposure, respectively. Several proteins were detected with altered abundance in response to H2O2, but not menadione/FeCl3 (i.e., valosin-containing protein, indicating distinct responses to these different forms of oxidative stress. One protein, cobalamin-independent methionine synthase, demonstrated a common response in both conditions, which may be a marker for a more general stress response mechanism. Further changes to the A. mellea proteome were investigated using MS-based proteomics, which identified changes to putative secondary metabolism (SM enzymes upon growth in agar compared to liquid cultures. Metabolomic analyses revealed distinct profiles, highlighting the effect of growth matrix on SM production. This establishes robust methods by which to utilize comparative proteomics to characterize this important phytopathogen.

  20. Hypoxia and Reoxygenation: a Possible Mechanism for Placental Oxidative Stress in Preeclampsia

    Directory of Open Access Journals (Sweden)

    Tai-Ho Hung

    2006-09-01

    Full Text Available Preeclampsia is a human pregnancy-specific disorder that is diagnosed by the new appearance of hypertension and proteinuria after 20 weeks' gestation. It is a leading cause of perinatal morbidity and mortality, and the only intervention that effectively reverses the syndrome is delivery. Oxidative stress of the placenta is considered to be a key intermediary step in the pathogenesis of preeclampsia, but the cause for the stress remains unknown. Hypoxia-reoxygenation (H/R injury, as a result of intermittent placental perfusion secondary to deficient trophoblast invasion of the endometrial arteries, is a possible mechanism. In this review, we present evidence to show that there is a plausible basis from which to assume that blood flow in the intervillous space will be intermittent in all normal pregnancies. The intermittency will be exacerbated by impaired conversion of the spiral arteries, or by the presence of atherotic changes that reduce their caliber as seen in preeclampsia. Placental oxidative stress can be the consequences of fluctuations in oxygen concentrations after H/R through the actions of reactive oxygen species. On this basis, there will be a complete spectrum of placental changes among the normal, the late onset and the early onset preeclamptic states. Viewing the syndrome as a continuum of H/R insults provides new insight into the pathophysiology of pregnancy that will hopefully lead to improved clinical interventions.

  1. HCV Core Protein Uses Multiple Mechanisms to Induce Oxidative Stress in Human Hepatoma Huh7 Cells

    Directory of Open Access Journals (Sweden)

    Alexander V. Ivanov

    2015-05-01

    Full Text Available Hepatitis C virus (HCV infection is accompanied by the induction of oxidative stress, mediated by several virus proteins, the most prominent being the nucleocapsid protein (HCV core. Here, using the truncated forms of HCV core, we have delineated several mechanisms by which it induces the oxidative stress. The N-terminal 36 amino acids of HCV core induced TGF\\(\\upbeta\\1-dependent expression of nicotinamide adenine dinucleotide phosphate (NADPH oxidases 1 and 4, both of which independently contributed to the production of reactive oxygen species (ROS. The same fragment also induced the expression of cyclo-oxygenase 2, which, however, made no input into ROS production. Amino acids 37–191 of HCV core up-regulated the transcription of a ROS generating enzyme cytochrome P450 2E1. Furthermore, the same fragment induced the expression of endoplasmic reticulum oxidoreductin 1\\(\\upalpha\\. The latter triggered efflux of Ca2+ from ER to mitochondria via mitochondrial Ca2+ uniporter, leading to generation of superoxide anions, and possibly also H2O2. Suppression of any of these pathways in cells expressing the full-length core protein led to a partial inhibition of ROS production. Thus, HCV core causes oxidative stress via several independent pathways, each mediated by a distinct region of the protein.

  2. Comparative proteomics of contrasting maize genotypes provides insights into salt-stress tolerance mechanisms.

    Science.gov (United States)

    Luo, Meijie; Zhao, Yanxin; Wang, Yuandong; Shi, Zi; Zhang, Panpan; Zhang, Yunxia; Song, Wei; Zhao, Jiuran

    2017-12-01

    Salt stress is a major abiotic factor limiting maize yield. To characterize the mechanism underlying maize salt tolerance, we compared the seedling root proteomes of salt-tolerant Jing724 and salt-sensitive D9H. The germination rate and growth parameter values (weight and length) were higher for Jing724 than for D9H under saline conditions. Using an iTRAQ-based method, we identified 513 differentially regulated proteins (DRPs), with 83 and 386 DRPs specific to Jing724 and D9H, respectively. In salt-stressed Jing724, the DRPs were primarily associated with the pentose phosphate pathway, glutathione metabolism, and nitrogen metabolism. Key DRPs, such as glucose-6-phosphate 1-dehydrogenase, NADPH-producing dehydrogenase, glutamate synthase, and glutamine synthetase, were identified based on pathway enrichment and protein-protein interaction analyses. Moreover, salt-responsive proteins in Jing724 seedlings were implicated in energy management, maintenance of redox homeostasis, detoxification of ammonia, regulation of osmotic homeostasis, stress defense and adaptation, biotic cross-tolerance, and regulation of gene expression. Quantitative analyses of superoxide dismutase activity, malondialdehyde content, relative electrolyte leakage, and proline content were consistent with the predicted changes based on DRP functions. Furthermore, changes in the abundance of eight representative DRPs were correlated with the corresponding mRNA levels. Our results may be useful for elucidating the molecular networks mediating salt tolerance.

  3. Anisotropic stress relief mechanism in epitaxial La0.67Sr0.33MnO3 films

    Science.gov (United States)

    Vailionis, Arturas; Boschker, Hans; Houwman, Evert; Koster, Gertjan; Rijnders, Guus; Blank, Dave H. A.

    2009-10-01

    We report an anisotropic misfit stress relief mechanism in thin La0.67Sr0.33MnO3 (LSMO) films coherently grown on NdGaO3(110) substrates. These results are uniquely related to the orthorhombicity of the LSMO. The x-ray diffraction measurements and quantitative simulations demonstrate that biaxial mismatch stress is relieved differently along in-plane directions perpendicular to each other: in the [11¯0] direction stress is accommodated by decrease of the γ angle of the orthorhombic LSMO unit cell, while in the [001] direction stress is partially relieved by periodic lattice modulations.

  4. Influence of constant current stress on the conduction mechanisms of reverse leakage current in UV-A light emitting diodes

    Science.gov (United States)

    Wang, Yingzhe; Zheng, Xuefeng; Dai, Feng; Zhu, Jiaduo; Li, Peixian; Ma, Xiaohua; Hao, Yue

    2017-12-01

    The influence of constant current stress on the conduction mechanism of reverse leakage current in ultraviolet (UV) light emitting diodes (LEDs) in the UV-A spectral range has been investigated for the first time using temperature-dependent current-voltage measurement from 370 K to 55 K. Below 220 K, variable range hopping mechanism dominates in UV-A LEDs. While, above 220 K, the leakage current is attributed to Poole-Frenkel emission mechanism within the bias range of -3 ∼ -6 V. With the increasing of the reverse bias, the conduction mechanism transforms from Poole-Frenkel emission to space-charge-limited conduction mechanism. In particular, applying electrical stress yields an alteration of the transition voltage from -7.5 V to -6.5 V. We propose that stress could lead to a reduction of the thermal activation energy, and therefore alters the transition voltage.

  5. Stress-induced formation mechanism of stacking fault tetrahedra in nano-cutting of single crystal copper

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Quanlong [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Center for Precision Engineering, Harbin Institute of Technology, Harbin 150001 (China); Bai, Qingshun [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Chen, Jiaxuan, E-mail: wangquanlong0@hit.edu.cn [Center for Precision Engineering, Harbin Institute of Technology, Harbin 150001 (China); Guo, Yongbo [Center for Precision Engineering, Harbin Institute of Technology, Harbin 150001 (China); Xie, Wenkun [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Center for Precision Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2015-11-15

    Graphical abstract: In this paper, molecular dynamics simulation is performed to study the distribution of dislocation defects and local atomic crystal structure of single crystal copper. The stress distribution is investigated which is calculated by virial stress and analyzed by static pressure. The results are shown in (a)–(d). It is indicated that the compressive stress mainly spreads over the shear-slip zone, and the tensile stress is consisted in flank friction zone, shown in (a). The high tensile stress in subsurface is the source of stress, shown in (b). By the driven action of the stress source, the initial stair-rod dislocation nucleates. Then the dislocation climbs along four {1 1 1} planes under the stress driven action, shown in (d). Finally, the SFT is formed by the interaction of the compressive stress and the tensile stress which come from the shear-slip zone and friction zone, respectively. Besides, stair-rod dislocation, stacking faults and dislocation loop are also nucleated in the subsurface, shown in (c). Dislocation distribution, local atomic crystal structure state and stress-induced formation process of SFT by atomic. - Highlights: • A novel defect structure “stress-induced stacking fault tetrahedra” is revealed. • Atomic structural evolution and stress state distribution of the SFT are studied. • The stress-induced formation mechanism of the SFT is proposed. - Abstract: Stacking fault tetrahedra commonly existed in subsurface of deformed face center cubic metals, has great influence on machining precision and surface roughness in nano-cutting. Here we report, a stacking fault tetrahedra is formed in subsurface of workpiece during nano-cutting. The variation of cutting force and subsurface defects distribution are studied by using molecular dynamics simulation. The stress distribution is investigated which is calculated by virial stress and analyzed by static compression. The result shows that the cutting force has a rapidly

  6. Exopolysaccharides produced by lactic acid bacteria: from health-promoting benefits to stress tolerance mechanisms.

    Science.gov (United States)

    Caggianiello, Graziano; Kleerebezem, Michiel; Spano, Giuseppe

    2016-05-01

    A wide range of lactic acid bacteria (LAB) is able to produce capsular or extracellular polysaccharides, with various chemical compositions and properties. Polysaccharides produced by LAB alter the rheological properties of the matrix in which they are dispersed, leading to typically viscous and "ropy" products. Polysaccharides are involved in several mechanisms such as prebiosis and probiosis, tolerance to stress associated to food process, and technological properties of food. In this paper, we summarize the beneficial properties of exopolysaccharides (EPS) produced by LAB with particular attention to prebiotic properties and to the effect of exopolysaccharides on the LAB-host interaction mechanisms, such as bacterial tolerance to gastrointestinal tract conditions, ability of ESP-producing probiotics to adhere to intestinal epithelium, their immune-modulatory activity, and their role in biofilm formation. The pro-technological aspect of exopolysaccharides is discussed, focusing on advantageous applications of EPS in the food industry, i.e., yogurt and gluten-free bakery products, since it was found that these microbial biopolymers positively affect the texture of foods. Finally, the involvement of EPS in tolerance to stress conditions that are commonly encountered in fermented beverages such as wine is discussed.

  7. Maximum-power-point tracking with reduced mechanical stress applied to wind-energy-conversion-systems

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, L.G. [Departamento de Electronica y Comunicaciones, Universidad de los Andes, nucleo la Hechicera, 5101 Merida (Venezuela); Figueres, E.; Garcera, G. [Grupo de Sistemas Electronicos Industriales, Universidad Politecnica de Valencia, Camino de vera s/n, 46022 Valencia (Spain); Carranza, O. [Escuela Superior de Computo, Instituto Politecnico Nacional, Av. Juan de Dios Batiz s/n, 07738 DF (Mexico)

    2010-07-15

    This paper presents an improved maximum-power-point tracking algorithm for wind-energy-conversion-systems. The proposed method significantly reduces the turbine mechanical stress with regard to conventional techniques, so that both the maintenance needs and the medium time between failures are expected to be improved. To achieve these objectives, a sensorless speed control loop receives its reference signal from a modified Perturb and Observe algorithm, in which the typical steps on the reference speed have been substituted by a fixed and well-defined slope ramp signal. As a result, it is achieved a soft dynamic response of both the torque and the speed of the wind turbine, so that the whole system suffers from a lower mechanical stress than with conventional P and O techniques. The proposed method has been applied to a wind turbine based on a permanent magnet synchronous generator operating at variable speed, which is connected to the distribution grid by means of a back to back converter. (author)

  8. Irregular focal mechanisms observed at Salton Sea Geothermal Field: Possible influences of anthropogenic stress perturbations

    Science.gov (United States)

    Crandall-Bear, Aren; Barbour, Andrew J.; Schoenball, Martin; Schoenball, Martin

    2018-01-01

    At the Salton Sea Geothermal Field (SSGF), strain accumulation is released through seismic slip and aseismic deformation. Earthquake activity at the SSGF often occurs in swarm-like clusters, some with clear migration patterns. We have identified an earthquake sequence composed entirely of focal mechanisms representing an ambiguous style of faulting, where strikes are similar but deformation occurs due to steeply-dipping normal faults with varied stress states. In order to more accurately determine the style of faulting for these events, we revisit the original waveforms and refine estimates of P and S wave arrival times and displacement amplitudes. We calculate the acceptable focal plane solutions using P-wave polarities and S/P amplitude ratios, and determine the preferred fault plane. Without constraints on local variations in stress, found by inverting the full earthquake catalog, it is difficult to explain the occurrence of such events using standard fault-mechanics and friction. Comparing these variations with the expected poroelastic effects from local production and injection of geothermal fluids suggests that anthropogenic activity could affect the style of faulting.

  9. WAXS studies of heat - mechanically modified amorphous PET fibers. Role of the tensile stress

    Science.gov (United States)

    Velev, V.; Popov, A.; Kyurkchiev, P.; Veleva, L.; Pencheva, M.

    2014-12-01

    The present work is devoted to the investigation of the structure developments in as- spun amorphous poly (ethylene terephthalate) (PET) filaments occurred as a result of heat mechanically modification. The degree of crystallinity of the untreated samples was 1,7 %. The thermal deformation experiments were carried out under isothermal conditions. PET yarn was annealed during 10 min at constant temperature of 80°C after which the sample is subjected to a well-defined constant tensile stress for 120 s at the same temperature. The mechanical load is gravitationally in the range from 0 MPa to 30 MPa and with increment step of 3 MPa. Using of wide angle X-ray scattering (WAXS) were investigated the structural rearrangements in the studied samples caused by the fibers treatments. Dependences between the strain force values and the running in the specimen's structure development are established. And in particular, it was found that a small increase of the tensile stress from 3 MPa to 6 MPa leads to a massive increase in the fibers degree of crystallinity with more than 33%.

  10. Study on tracheal collapsibility, compliance, and stress by considering nonlinear mechanical property of cartilage.

    Science.gov (United States)

    Teng, Zhongzhao; Ochoa, Ignacio; Li, Zhiyong; Liao, Zijie; Lin, Yihan; Doblare, Manuel

    2009-11-01

    Tracheal cartilage has been widely regarded as a linear elastic material either in experimental studies or in analytic and numerical models. However, it has been recently demonstrated that, like other fiber-oriented biological tissues, tracheal cartilage is a nonlinear material, which displays higher strength in compression than in extension. Considering the nonlinearity requires a more complex theoretical frame work and costs more to simulate. This study aims to quantify the deviation due to the simplified treatment of the tracheal cartilage as a linear material. It also evaluates the improved accuracy gained by considering the nonlinearity. Pig tracheal rings were used to exam the mechanical properties of cartilage and muscular membrane. By taking into account the asymmetric shape of tracheal cartilage, the collapse behavior of complete rings was simulated, and the compliance of airway and stress in the muscular membrane were discussed. The results obtained were compared with those assuming linear mechanical properties. The following results were found: (1) Models based on both types of material properties give a small difference in representing collapse behavior; (2) regarding compliance, the relative difference is big, ranging from 10 to 40% under negative pressure conditions; and (3) the difference in determining stress in the muscular membrane is small too: transmural pressure is lower than -0.5 kPa. The results obtained in this study may be useful in both understanding the collapse behavior of trachea and in evaluating the error induced by the simplification of treating the tracheal cartilage as a linear elastic material.

  11. Dissecting Regional Variations in Stress Fiber Mechanics in Living Cells with Laser Nanosurgery

    Energy Technology Data Exchange (ETDEWEB)

    Tanner, Kandice; Boudreau, Aaron; Bissell, Mina J; Kumar, Sanjay

    2010-03-02

    The ability of a cell to distribute contractile stresses across the extracellular matrix in a spatially heterogeneous fashion underlies many cellular behaviors, including motility and tissue assembly. Here we investigate the biophysical basis of this phenomenon by using femtosecond laser nanosurgery to measure the viscoelastic recoil and cell-shape contributions of contractile stress fibers (SFs) located in specific compartments of living cells. Upon photodisruption and recoil, myosin light chain kinase-dependent SFs located along the cell periphery display much lower effective elasticities and higher plateau retraction distances than Rho-associated kinase-dependent SFs located in the cell center, with severing of peripheral fibers uniquely triggering a dramatic contraction of the entire cell within minutes of fiber irradiation. Image correlation spectroscopy reveals that when one population of SFs is pharmacologically dissipated, actin density flows toward the other population. Furthermore, dissipation of peripheral fibers reduces the elasticity and increases the plateau retraction distance of central fibers, and severing central fibers under these conditions triggers cellular contraction. Together, these findings show that SFs regulated by different myosin activators exhibit different mechanical properties and cell shape contributions. They also suggest that some fibers can absorb components and assume mechanical roles of other fibers to stabilize cell shape.

  12. Lithium-ion battery aging mechanisms and life model under different charging stresses

    Science.gov (United States)

    Gao, Yang; Jiang, Jiuchun; Zhang, Caiping; Zhang, Weige; Ma, Zeyu; Jiang, Yan

    2017-07-01

    The charging time-consuming and lifespan of lithium-ion batteries have always been the bottleneck for the tremendous application of electric vehicles. In this paper, cycle life tests are conducted to reveal the influence of different charging current rates and cut-off voltages on the aging mechanism of batteries. The long-term effects of charging current rates and cut-off voltages on capacity degradation and resistance increase are compared. The results show that there exists a critical charging current and a critical charging cut-off voltage. When the charging stress exceeds the critical value, battery degradation speed will be greatly accelerated. Furthermore, battery aging mechanisms at various charging currents and cut-off voltages are investigated using incremental capacity analysis. It is indicated that charging current and cut-off voltage should be reduced to retard battery degradation when the battery degrades to a certain extent. The time when the loss of electrode material accelerates is taken as the crisis to reduce charging current and the time when the loss of lithium inventory accelerates is taken as the crisis to reduce charging cut-off voltage. Moreover, an experiential model quantitatively describing the relationship between capacity degradation rate and charging stresses at different aging states is established.

  13. The Capacity-Building Stewardship Model: assessment of an agricultural network as a mechanism for improving regional agroecosystem sustainability

    Directory of Open Access Journals (Sweden)

    Alison J. Duff

    2017-03-01

    Full Text Available Working lands have potential to meet agricultural production targets while serving as reservoirs of biological diversity and as sources of ecological services. Yet agricultural policy creates disincentives for this integration of conservation and production goals. While necessary, the development of a policy context that promotes agroecosystem sustainability will take time, and successful implementation will depend on a receptive agricultural audience. As the demands placed on working lands grow, there is a need for regional support networks that build agricultural producers' capacity for land stewardship. We used a social-ecological system framework to illustrate the Healthy Grown Potato Program as an agricultural network case study. Our Capacity-Building Stewardship Model reflects a 20-year experience working in collaboration with potato growers certified under an ecolabel in Wisconsin, USA. The model applies an evolving, modular farm stewardship standard to the entire farm - croplands and noncroplands. The model demonstrates an effective process for facilitating communication and shared learning among program participants, including agricultural producers, university extension specialists, nonprofit conservation partners, and industry representatives. The limitation of the model in practice has been securing funding to support expansion of the program and to ensure that the ecolabel standard is responsive to changes in the social-ecological system. Despite this constraint, the Capacity-Building Stewardship Model reveals an important mechanism for building regional commitment to conservation, with agricultural producers in a leadership role as architects, adopters, and advocates for stewardship behavior. Our experience provides important insight for the application of agri-environment schemes on private lands. The durability of a conservation ethic on working farms is likely to be enhanced when networks engage and support producers in an

  14. Mechanism of H2S-mediated protection against oxidative stress in Escherichia coli.

    Science.gov (United States)

    Mironov, Alexander; Seregina, Tatyana; Nagornykh, Maxim; Luhachack, Lyly G; Korolkova, Natalya; Lopes, Liubov Errais; Kotova, Vera; Zavilgelsky, Gennady; Shakulov, Rustem; Shatalin, Konstantin; Nudler, Evgeny

    2017-06-06

    Endogenous hydrogen sulfide (H2S) renders bacteria highly resistant to oxidative stress, but its mechanism remains poorly understood. Here, we report that 3-mercaptopyruvate sulfurtransferase (3MST) is the major source of endogenous H2S in Escherichia coli Cellular resistance to H2O2 strongly depends on the activity of mstA, a gene that encodes 3MST. Deletion of the ferric uptake regulator (Fur) renders ∆mstA cells hypersensitive to H2O2 Conversely, induction of chromosomal mstA from a strong pLtetO-1 promoter (P tet -mstA) renders ∆fur cells fully resistant to H2O2 Furthermore, the endogenous level of H2S is reduced in ∆fur or ∆sodA ∆sodB cells but restored after the addition of an iron chelator dipyridyl. Using a highly sensitive reporter of the global response to DNA damage (SOS) and the TUNEL assay, we show that 3MST-derived H2S protects chromosomal DNA from oxidative damage. We also show that the induction of the CysB regulon in response to oxidative stress depends on 3MST, whereas the CysB-regulated l-cystine transporter, TcyP, plays the principle role in the 3MST-mediated generation of H2S. These findings led us to propose a model to explain the interplay between l-cysteine metabolism, H2S production, and oxidative stress, in which 3MST protects E. coli against oxidative stress via l-cysteine utilization and H2S-mediated sequestration of free iron necessary for the genotoxic Fenton reaction.

  15. Exploring the molecular mechanism of acute heat stress exposure in broiler chickens using gene expression profiling.

    Science.gov (United States)

    Luo, Q B; Song, X Y; Ji, C L; Zhang, X Q; Zhang, D X

    2014-08-10

    The process of heat regulation is complex and its exact molecular mechanism is not fully understood. In this study, to investigate the global gene regulation response to acute heat exposure, gene microarrays were exploited to analyze the effects of heat stress on three tissues (brain, liver, leg muscle) of the yellow broiler chicken (Gallus gallus). We detected 166 differentially expressed genes (DEGs) in the brain, 219 in the leg muscle and 317 in the liver. Six of these genes were differentially expressed in all three tissues and were validated by qRT-PCR, and included heat shock protein genes (HSPH1, HSP25), apoptosis-related genes (RB1CC1, BAG3), a cell proliferation and differentiation-related gene (ID1) and the hunger and energy metabolism related gene (PDK). All these genes might be important factors in chickens suffering from heat stress. We constructed gene co-expression networks using the DEGs of the brain, leg muscle and liver and two, four and two gene co-expression modules were identified in these tissues, respectively. Functional enrichment of these gene modules revealed that various functional clusters were related to the effects of heat stress, including those for cytoskeleton, extracellular space, ion binding and energy metabolism. We concluded that these genes and functional clusters might be important factors in chickens under acute heat stress. Further in-depth research on the newly discovered heat-related genes and functional clusters is required to fully understand their molecular functions in thermoregulation. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Growth and stress response mechanisms underlying post-feeding regenerative organ growth in the Burmese python.

    Science.gov (United States)

    Andrew, Audra L; Perry, Blair W; Card, Daren C; Schield, Drew R; Ruggiero, Robert P; McGaugh, Suzanne E; Choudhary, Amit; Secor, Stephen M; Castoe, Todd A

    2017-05-02

    Previous studies examining post-feeding organ regeneration in the Burmese python (Python molurus bivittatus) have identified thousands of genes that are significantly differentially regulated during this process. However, substantial gaps remain in our understanding of coherent mechanisms and specific growth pathways that underlie these rapid and extensive shifts in organ form and function. Here we addressed these gaps by comparing gene expression in the Burmese python heart, liver, kidney, and small intestine across pre- and post-feeding time points (fasted, one day post-feeding, and four days post-feeding), and by conducting detailed analyses of molecular pathways and predictions of upstream regulatory molecules across these organ systems. Identified enriched canonical pathways and upstream regulators indicate that while downstream transcriptional responses are fairly tissue specific, a suite of core pathways and upstream regulator molecules are shared among responsive tissues. Pathways such as mTOR signaling, PPAR/LXR/RXR signaling, and NRF2-mediated oxidative stress response are significantly differentially regulated in multiple tissues, indicative of cell growth and proliferation along with coordinated cell-protective stress responses. Upstream regulatory molecule analyses identify multiple growth factors, kinase receptors, and transmembrane receptors, both within individual organs and across separate tissues. Downstream transcription factors MYC and SREBF are induced in all tissues. These results suggest that largely divergent patterns of post-feeding gene regulation across tissues are mediated by a core set of higher-level signaling molecules. Consistent enrichment of the NRF2-mediated oxidative stress response indicates this pathway may be particularly important in mediating cellular stress during such extreme regenerative growth.

  17. Transcriptomic analysis of Pak Choi under acute ozone exposure revealed regulatory mechanism against ozone stress.

    Science.gov (United States)

    Zhang, Lu; Xu, Bin; Wu, Tao; Wen, Mu-Xuan; Fan, Lian-Xue; Feng, Zhao-Zhong; Paoletti, Elena

    2017-12-08

    Ground-level ozone (O3) is one of the major air pollutants, which cause oxidative injury to plants. The physiological and biochemical mechanisms underlying the responses of plants to O3 stress have been well investigated. However, there are limited reports about the molecular basis of plant responses to O3. In this study, a comparative transcriptomic analysis of Pak Choi (Brassica campestris ssp. chinensis) exposed to different O3 concentrations was conducted for the first time. Seedlings of Pak Choi with five leaves were exposed to non-filtered air (NF, 31 ppb) or elevated O3 (E-O3, 252 ppb) for 2 days (8 h per day, from 9:00-17:00). Compared with plants in the NF, a total of 675 differentially expressed genes (DEGs) were identified in plants under E-O3, including 219 DEGs with decreased expressions and 456 DEGs with increased expressions. Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that O3 stress invoked multiple cellular defense pathways to mitigate the impaired cellular integrity and metabolism, including 'glutathione metabolism', 'phenylpropanoid biosynthesis', 'sulfur metabolism', 'glucosinolate biosynthesis', 'cutin, suberine and wax biosynthesis' and others. Transcription factors potentially involved in this cellular regulation were also found, such as AP2-ERF, WRKY, JAZ, MYB etc. Based on the RNA-Seq data and previous studies, a working model was proposed integrating O3 caused reactive oxygen burst, oxidation-reduction regulation, jasmonic acid and downstream functional genes for the regulation of cellular homeostasis after acute O3 stress. The present results provide a valuable insight into the molecular responses of Pak Choi to acute O3 stress and the specific DEGs revealed in this study could be used for further functional identification of key allelic genes determining the O3 sensitivity of Pak Choi.

  18. Dissection of Ire1 functions reveals stress response mechanisms uniquely evolved in Candida glabrata.

    Directory of Open Access Journals (Sweden)

    Taiga Miyazaki

    2013-01-01

    Full Text Available Proper protein folding in the endoplasmic reticulum (ER is vital in all eukaryotes. When misfolded proteins accumulate in the ER lumen, the transmembrane kinase/endoribonuclease Ire1 initiates splicing of HAC1 mRNA to generate the bZIP transcription factor Hac1, which subsequently activates its target genes to increase the protein-folding capacity of the ER. This cellular machinery, called the unfolded protein response (UPR, is believed to be an evolutionarily conserved mechanism in eukaryotes. In this study, we comprehensively characterized mutant phenotypes of IRE1 and other related genes in the human fungal pathogen Candida glabrata. Unexpectedly, Ire1 was required for the ER stress response independently of Hac1 in this fungus. C. glabrata Ire1 did not cleave mRNAs encoding Hac1 and other bZIP transcription factors identified in the C. glabrata genome. Microarray analysis revealed that the transcriptional response to ER stress is not mediated by Ire1, but instead is dependent largely on calcineurin signaling and partially on the Slt2 MAPK pathway. The loss of Ire1 alone did not confer increased antifungal susceptibility in C. glabrata contrary to UPR-defective mutants in other fungi. Taken together, our results suggest that the canonical Ire1-Hac1 UPR is not conserved in C. glabrata. It is known in metazoans that active Ire1 nonspecifically cleaves and degrades a subset of ER-localized mRNAs to reduce the ER load. Intriguingly, this cellular response could occur in an Ire1 nuclease-dependent fashion in C. glabrata. We also uncovered the attenuated virulence of the C. glabrata Δire1 mutant in a mouse model of disseminated candidiasis. This study has unveiled the unique evolution of ER stress response mechanisms in C. glabrata.

  19. Research on Formation Mechanism of Dynamic Response and Residual Stress of Sheet Metal Induced by Laser Shock Wave

    Science.gov (United States)

    Feng, Aixin; Cao, Yupeng; Wang, Heng; Zhang, Zhengang

    2018-01-01

    In order to reveal the quantitative control of the residual stress on the surface of metal materials, the relevant theoretical and experimental studies were carried out to investigate the dynamic response of metal thin plates and the f