Science.gov

Sample records for damage formation due

  1. Radiation damage due to electromagnetic showers

    SciTech Connect

    Rakhno, Igor; Mokhov, Nikolai; Striganov, Sergei; /Fermilab

    2008-05-01

    Radiation-induced damage due to atomic displacements is essential to correctly predict the behavior of materials in nuclear reactors and at charged-particle accelerators. Traditionally the damage due to hadrons was of major interest. The recent increased interest in high-energy lepton colliders gave rise to the problem of prediction of radiation damage due to electromagnetic showers in a wide energy range--from a few hundred keV and up to a few hundred GeV. The report describes results of an electron- and positron-induced displacement cross section evaluation. It is based on detailed lepton-nucleus cross sections, realistic nuclear form-factors and a modified Kinchin-Pease damage model. Numerical data on displacement cross sections for various target nuclei is presented.

  2. Pipeline damage due to wave propagation

    SciTech Connect

    O'Rourke, M. ); Ayala, G. . Inst. de Ingenieria)

    1993-09-01

    Based on data from three US earthquakes Barenberg (1988) established an empirical relation between seismic wave propagation damage to cast iron pipe and peak horizontal particle velocity, V[sub max]. Additional data from the 1983 Coalinga earthquakes and two Mexican earthquakes suggest that damage ratios in repairs per kilometer, for some other common pipe materials (specifically asbestos cement, concrete, and prestressed concrete cylinder pipe) used for water transmission and distribution follow the same general trend as that for cast iron. The authors data does not include relatively flexible pipe materials such as ductile iron (DI). One expects that the wave propagation damage ratio for these materials to be somewhat less than that for the relatively brittle materials. The best case scenario overestimates observed damage by a factor of two for some of the data points and underestimates observed damage by a factor of three for a few others. When estimating expected water system damage due to future seismic activity, it is suggested that the characteristics of the given system (brittle or flexible pipe materials, relatively uniform or variable subsurface conditions, corrosive or noncorrosive soils) be considered. Although analytical estimates exist, they do not at present cover a broad enough range of damage mechanism to be of use to water officials in estimating seismic wave propagation damage to buried pipelines. However analytical procedures that quantify damage in terms of the relative axial extension or the axial compression force at a joint may prove useful in the future in establishing design criterion for seismically resistant pipe.

  3. Crater Formation Due to Lunar Plume Impingement

    NASA Technical Reports Server (NTRS)

    Marsell, Brandon

    2011-01-01

    Thruster plume impingement on a surface comprised of small, loose particles may cause blast ejecta to be spread over a large area and possibly cause damage to the vehicle. For this reason it is important to study the effects of plume impingement and crater formation on surfaces like those found on the moon. Lunar soil, also known as regolith, is made up of fine granular particles on the order of 100 microns.i Whenever a vehicle lifts-off from such a surface, the exhaust plume from the main engine will cause the formation of a crater. This crater formation may cause laterally ejected mass to be deflected and possibly damage the vehicle. This study is a first attempt at analyzing the dynamics of crater formation due to thruster exhaust plume impingement during liftoff from the moon. Though soil erosion on the lunar surface is not considered, this study aims at examining the evolution of the shear stress along the lunar surface as the engine fires. The location of the regions of high shear stress will determine where the crater begins to form and will lend insight into how big the crater will be. This information will help determine the probability that something will strike the vehicle. The final sections of this report discuss a novel method for studying this problem that uses a volume of fluid (VOF)ii method to track the movement of both the exhaust plume and the eroding surface.

  4. Formation of ion damage tracks. [in insulators

    NASA Technical Reports Server (NTRS)

    Tombrello, T. A.; Wie, C. R.; Itoh, N.; Nakayama, T.

    1984-01-01

    A new model is proposed to explain both localized damage regions and preferential etching of damage tracks caused by the passage of energetic ions in insulators. The formation of each region of extended defects is initiated by the Auger decay of a vacancy produced in an inner electronic shell of an atom of the insulator by an incident ion. This decay produces an intense source of ionization within a small volume around the decaying atom, which causes decomposition of the material in a manner similar to that observed in pulsed laser irradiation. The resulting chemical or crystalline modification of the material is the latent track, which can be preferentially etched due to its changed structure.

  5. Brittle dynamic damage due to earthquake rupture

    NASA Astrophysics Data System (ADS)

    Bhat, Harsha; Thomas, Marion

    2016-04-01

    The micromechanical damage mechanics formulated by Ashby and Sammis, 1990, and generalized by Deshpande and Evans 2008 has been extended to allow for a more generalized stress state and to incorporate an experimentally motivated new crack growth (damage evolution) law that is valid over a wide range of loading rates. This law is sensitive to both the crack tip stress field and its time derivative. Incorporating this feature produces additional strain-rate sensitivity in the constitutive response. The model is also experimentally verified by predicting the failure strength of Dionysus-Pentelicon marble over wide range of strain rates. We then implement this constitutive response to understand the role of dynamic brittle off-fault damage on earthquake ruptures. We show that off-fault damage plays an important role in asymmetry of rupture propagation and is a source of high-frequency ground motion in the near source region.

  6. Modelling direct tangible damages due to natural hazards

    NASA Astrophysics Data System (ADS)

    Kreibich, H.; Bubeck, P.

    2012-04-01

    Europe has witnessed a significant increase in direct damages from natural hazards. A further damage increase is expected due to the on-going accumulation of people and economic assets in risk-prone areas and the effects of climate change, for instance, on the severity and frequency of drought events in the Mediterranean basin. In order to mitigate the impact of natural hazards an improved risk management based on reliable risk analysis is needed. Particularly, there is still much research effort needed to improve the modelling of damage due to natural hazards. In comparison with hazard modelling, simple approaches still dominate damage assessments, mainly due to limitations in available data and knowledge on damaging processes and influencing factors. Within the EU-project ConHaz, methods as well as data sources and terminology for damage assessments were compiled, systemized and analysed. Similarities and differences between the approaches concerning floods, alpine hazards, coastal hazards and droughts were identified. Approaches for significant improvements of direct tangible damage modelling with a particular focus on cross-hazard-learning will be presented. Examples from different hazards and countries will be given how to improve damage data bases, the understanding of damaging processes, damage models and how to conduct improvements via validations and uncertainty analyses.

  7. Effect of tensile stress on cavitation damage formation in mercury

    NASA Astrophysics Data System (ADS)

    Naoe, Takashi; Kogawa, Hiroyuki; Yamaguchi, Yoshihito; Futakawa, Masatoshi

    2010-03-01

    Cavitation erosion or so called pitting damage was investigated under tensile stress conditions in mercury. In MW-class liquid metal spallation targets, pitting damage is a critical issue to satisfy required power and/or lifetime of the target vessel. Cavitation occurs by negative pressure which is induced through pressure wave propagation due to proton beam injection. Pitting damage is formed by microjet and/or shock wave during cavitation bubble collapse. A mercury target vessel suffers tensile stress due to thermal stress or welding. In order to investigate the effect of tensile stress on pitting damage formation, cavitation erosion tests were performed using stress imposed specimens in mercury. An ultrasonic vibratory horn and electro-Magnetic IMpact Testing Machine (MIMTM) were used to vary the cavitation intensity. In the incubation period of pitting damage, damaged area was slightly increased with increasing imposed tensile stress. In the steady state period, a mean depth of erosion was increased by the tensile stress. Additionally, in order to quantitatively evaluate the effect of tensile stress, an indentation test with Vickers indenter was carried out to quasi-statically simulate the impact load. From the measurement of the diagonal length of the indent aspect ratio and hardness, it is recognized that the threshold of the deformation, i.e. pitting damage formation, was decreased by the tensile stress.

  8. Modelling of elastoplastic damage in concrete due to desiccation shrinkage

    NASA Astrophysics Data System (ADS)

    Bourgeois, F.; Burlion, N.; Shao, J. F.

    2002-07-01

    We present a numerical modelling of elastoplastic damage due to drying shrinkage of concrete in the framework of mechanics of partially saturated porous media. An elastoplastic model coupled with isotropic damage is first formulated. Two plastic flow mechanisms are involved, controlled by applied stress and suction, respectively. A general concept of net effective stress is used in take into account effects of capillary pressure and material damage on stress-controlled plastic deformation. Damage evolution depends both on elastic and plastic strains. The model's parameters are determined or chosen from relevant experimental data. Comparisons between numerical simulations and experimental data are presented to show the capacity of model to reproduce mains features of concrete behaviour under mechanical loading and during drying shrinkage of concrete. An example of application concerning drying of a concrete wall is finally presented. The results obtained allow to show potential capacity of proposed model for numerical modelling of complex coupling processes in concrete structures.

  9. Exploring aggregate economic damage functions due to climate change

    SciTech Connect

    Dowlatabadi, H.; Kandlikar, M.; Patwardhan, A.

    1994-12-31

    A number of issues need to be considered when developing aggregated economic damage functions due to climate change. These include: (i) identification of production processes vulnerable to climate change, (ii) an understanding of the mechanism of vulnerability, (iii) the rate of technological advance and diffusion (iv) the issue of detection of damages and availability of response options. In this paper we will explore the implications of these considerations with the aid of an illustrative model. The findings suggest that there is a significant upward bias in damage functions calculated without consideration of these issues. Furthermore, this systematic bias is larger as climate change increases. We believe the approach explored here is a more suitable model for adoption in future integrated assessments of climate change.

  10. CO/sub 2/ formation damage study. Final report

    SciTech Connect

    Patton, J.T.

    1983-07-01

    The literature did provide insight into four possible damage mechanisms, namely: (1) precipitation of reservoir mineral in the vicinity around the producing well as carbon dioxide escapes from the water phase due to pressure draw down; (2) plugging of reservoir interstices by insoluble organic solids precipitated as the carbon dioxide dissolves in crude oil; (3) formation of an immobile gas phase, predominately CO/sub 2/, which would drastically lower the effective permeability to oil and, especially water; and (4) dissolution of cementation, especially carbonates or feldspars, that could allow fines to migrate in the reservoir and plug tiny flow passages. Each of these mechanisms was investigated in depth during the laboratory experiments. Occasional reports from industry suggested that the use of carbon dioxide to enhance the recovery of tertiary oil might be causing formation damage. This project was undertaken to define the mechanisms responsible for such occurrences. The objectives were threefold: (1) provide a comprehensive literature survey to elicit all that is currently known or suspected, relative to formation damage that might occur during the injection of carbon dioxide into an oil reservoir; (2) under simulated reservoir conditions, demonstrate in the laboratory each of the damage mechanisms and quantify the degree to which each mechanism could cause damage; and (3) for those damage mechanisms identified to be significant, develop a feasible remedy, easily applied in actual field operations. The third mechanism, related to the presence of an immobile gas phase, is a real problem but not unique to the injection of carbon dioxide. In the case of carbon dioxide, the damage should be self-correcting, as the solubility of carbon dioxide in water will eventually allow the water to dissolve away the gas and, hence, the blocking effect.

  11. Shear degradation in fiber reinforced laminates due to matrix damage

    NASA Astrophysics Data System (ADS)

    Salavatian, Mohammedmahdi

    The objective of this study was to develop and implement a shear modulus degradation model to improve the failure analysis of the fiber reinforced composite structures. Matrix damage, involving transverse and shear cracks, is a common failure mode for composite structures, yet little is known concerning their interaction. To understand the material behavior after matrix failure, the nonlinear response of the composite laminate was studied using pressure vessels made from a [+/-o] bias orientation, which tend to exhibit a matrix dominated failure. The result of this work showed laminate matrix hardening in shear and softening in the transverse direction. A modified Iosipescu coupon was proposed to study the evolution of shear and transverse damage and their mutual effects. The proposed method showed good agreement with tubular results and has advantages of simplified specimen fabrication using standard test fixtures. The proposed method was extended by introducing a novel experimental technique to study the shear degradation model under biaxial loading. Experimental results of the transverse modulus reduction were in good agreement with material degradation models, while the predicted shear modulus reduction was higher than experiment. The discrepancy between available models and observations was due to the presence of a traction between the crack surfaces. Accordingly, a closed form solution was proposed for the shear stress-strain field of a cracked laminate by replacing the cracks with cohesive zones. The constitutive equations of the crack laminate were derived including the effects of internal tractions and transverse stress on the shear modulus. The proposed analytical model was shown to be the most comprehensive model for shear modulus degradation reduction of the fiber reinforced laminates. A numerical implementation of the shear degradation model was done using continuum damage mechanics. Through this work it was shown the common assumption of a linear

  12. Irradiation creep due to SIPA under cascade damage conditions

    SciTech Connect

    Woo, C.H.; Garner, F.A.; Holt, R.A.

    1992-12-31

    This paper derives the relationships between void swelling and irradiation creep due to Stress-Induced Preferred Absorption (SIPA) and SIPA-Induced Growth (SIG) under cascade damage conditions in an irradiated pressurized tube. It is found that at low swelling rates irradiation creep is a major contribution to the total diametral strain rate of the tube, whereas at high swelling rates the creep becomes a minor contribution. The anisotropy of the corresponding dislocation structure is also predicted to decline as the swelling rate increases. The theoretical predictions are found to agree very well with experimental results.

  13. Excavation Damaged Zones In Rock Salt Formations

    SciTech Connect

    Jockwer, N.; Wieczorek, K.

    2008-07-01

    Salt formations have long been proposed as potential host rocks for nuclear waste disposal. After the operational phase of a repository the openings, e.g., boreholes, galleries, and chambers, have to be sealed in order to avoid the release of radionuclides into the biosphere. For optimising the sealing techniques knowledge about the excavation damaged zones (EDZ) around these openings is essential. In the frame of a project performed between 2004 and 2007, investigations of the EDZ evolution were performed in the Stassfurt halite of the Asse salt mine in northern Germany. Three test locations were prepared in the floor of an almost 20 year old gallery on the 800-m level of the Asse mine: (1) the drift floor as existing, (2) the new drift floor shortly after removing of a layer of about 1 m thickness of the floor with a continuous miner, (3) the new drift floor 2 years after cutting off the 1-m layer. Subject of investigation were the diffusive and advective gas transport and the advective brine transport very close to the opening. Spreading of the brine was tracked by geo-electric monitoring in order to gain information about permeability anisotropy. Results obtained showed that EDZ cut-off is a useful method to improve sealing effectiveness when constructing technical barriers. (authors)

  14. Assessment of damage to the desert surfaces of Kuwait due to the Gulf War

    SciTech Connect

    El-Baz, F. . Center for Remote Sensing); Al-Ajmi, D. . Environmental and Earth Sciences Div.)

    1993-01-01

    This is a preliminary report on a joint research project by Boston University and the Kuwait Institute for Scientific Research that commenced in April 1992. The project aim is to establish the extent and nature of environmental damage to the desert surface and coastal zone of Kuwait due to the Gulf War and its aftermath. Change detection image enhancement techniques were employed to enhance environmental change by comparison of Landsat Thematic Mapper images obtained before the wars and after the cessation of the oil and well fires. Higher resolution SPOT images were also utilized to evaluate the nature of the environmental damage to specific areas. The most prominent changes were due to: (1) the deposition of oil and course-grained soot on the desert surface as a result of oil rain'' from the plume that emanated from the oil well fires; (2) the formation of hundreds of oil lakes, from oil seepage at the damaged oil well heads; (3) the mobilization of sand and dust and (4) the pollution of segments of the coastal zone by the deposition of oil from several oil spills. Interpretation of satellite image data are checked in the field to confirm the observations, and to assess the nature of the damage. Final results will be utilized in establishing the needs for remedial action to counteract the harmful effects of the various types of damage to the environment of Kuwait.

  15. Study of Damages on Home Electric Appliances due to Lightning

    NASA Astrophysics Data System (ADS)

    Hosokawa, Takeshi; Yokoyama, Sigeru; Yokota, Tsutomu

    Lightning damages of home electric appliances occurred in 154houses of 6,024monitors, were gathered in summer and winter seasons of 1987-1991 and 1996-1997. Types of damaged home appliances are summarized and extent of the damages are investigated. Furthermore the magnitude of invading lightning currents and the path of the invasion were estimated by means of inspections of the inner circuits of damaged home appliances and the experimental verifications. These investigations can lead to the development of lightning protection methods for home electric appliances of this highly computerized society.

  16. A Kinetic Model for Cell Damage Caused by Oligomer Formation.

    PubMed

    Hong, Liu; Huang, Ya-Jing; Yong, Wen-An

    2015-10-06

    It is well known that the formation of amyloid fiber may cause invertible damage to cells, although the underlying mechanism has not been fully understood. In this article, a microscopic model considering the detailed processes of amyloid formation and cell damage is constructed based on four simple assumptions, one of which is that cell damage is raised by oligomers rather than mature fibrils. By taking the maximum entropy principle, this microscopic model in the form of infinite mass-action equations together with two reaction-convection partial differential equations (PDEs) has been greatly coarse-grained into a macroscopic system consisting of only five ordinary differential equations (ODEs). With this simple model, the effects of primary nucleation, elongation, fragmentation, and protein and seeds concentration on amyloid formation and cell damage have been extensively explored and compared with experiments. We hope that our results will provide new insights into the quantitative linkage between amyloid formation and cell damage.

  17. Damage in porous media due to salt crystallization.

    PubMed

    Shahidzadeh-Bonn, Noushine; Desarnaud, Julie; Bertrand, François; Chateau, Xavier; Bonn, Daniel

    2010-06-01

    We investigate the origins of salt damage in sandstones for the two most common salts: sodium chloride and sulfate. The results show that the observed difference in damage between the two salts is directly related to the kinetics of crystallization and the interfacial properties of the salt solutions and crystals with respect to the stone. We show that, for sodium sulfate, the existence of hydrated and anhydrous crystals and specifically their dissolution and crystallization kinetics are responsible for the damage. Using magnetic resonance imaging and optical microscopy we show that when water imbibes sodium sulfate contaminated sandstones, followed by drying at room temperature, large damage occurs in regions where pores are fully filled with salts. After partial dissolution, anhydrous sodium sulfate salt present in these regions gives rise to a very rapid growth of the hydrated phase of sulfate in the form of clusters that form on or close to the remaining anhydrous microcrystals. The rapid growth of these clusters generates stresses in excess of the tensile strength of the stone leading to the damage. Sodium chloride only forms anhydrous crystals that consequently do not cause damage in the experiments.

  18. Concept Formation Ability in Brain-Damaged and Normal Children

    ERIC Educational Resources Information Center

    Townes, Brenda D.; And Others

    1978-01-01

    Comparisons were made between 27 normal and 27 brain damaged children (5-8 years old) on a variety of concept formation tasks from the Reitan-Indiana Neuropsychological Test Battery for Children. (CL)

  19. Biological consequences of formation and repair of complex DNA damage.

    PubMed

    Magnander, Karin; Elmroth, Kecke

    2012-12-31

    Endogenous processes or genotoxic agents can induce many types of single DNA damage (single-strand breaks, oxidized bases and abasic sites). In addition, ionizing radiation induces complex lesions such as double-strand breaks and clustered damage. To preserve the genomic stability and prevent carcinogenesis, distinct repair pathways have evolved. Despite this, complex DNA damage can cause severe problems and is believed to contribute to the biological consequences observed in cells exposed to genotoxic stress. In this review, the current knowledge of formation and repair of complex DNA damage is summarized and the risks and biological consequences associated with their repair are discussed. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  20. Vibrometric Detection of Beam Damage Due to Inclusions

    DTIC Science & Technology

    2004-03-01

    fatigue cracks, thermal exposure, overstressing, etc. The central focus of SHM is to identify the presence of a change in structural integrity as...vibration monitoring for damage presence began with rotor cracking in machinery and railroad equipment, as presented by Dimaroganas (1970) and Nagy...Dousis, and Finch (1978). The latter work has been noted to explain that “the presence of cracks [in railroad wheels] causes some resonance

  1. Future Radiation Damage in Space due to South Atlantic Anomaly

    NASA Technical Reports Server (NTRS)

    Heirtzler, J. R.

    1999-01-01

    Predictions of radiation damage for Low Earth Orbit (LEO) satellites now use semi-empirical models developed from prior satellite data. From these models it is clear that the low field strength of the South Atlantic Anomaly (SAA) controls where the maximum radiation damage occurs. One may make an estimate of future radiation damage to LEO spacecraft if one can predict the future of the SAA. Although reliable maps of the geomagnetic field strength and its secular change have only been made in the last few decades, certain geomagnetic observatories in South America and Africa have recorded the geomagnetic field for a much longer time. These observatories show that the present geomagnetic field change has persisted for more than 100 years. In spite of the fact that a few observatories have shown sudden changes in secular variation, those around the SAA have shown a stable secular variation. Assuming that this will continue for the next 50 to 100 years one can show that the SAA will expand to cover most of the South Atlantic Ocean and will become much weaker. This will greatly intensify the radiation hazard in LEO, put significant new limitations on radiation-hardened hardware, severely restrict the length of time that humans can remain in orbit, and materially change the configuration of the radiation belts.

  2. Drill-in fluid reduces formation damage, increases production rates

    SciTech Connect

    Hands, N.; Kowbel, K.; Nouris, R.

    1998-07-13

    A sodium formate drill-in fluid system reduced formation damage, resulting in better-than-expected production rates for an off-shore Dutch development well. Programmed to optimize production capacity and reservoir drainage from a Rotliegend sandstone gas discovery, the 5-7/8-in. subhorizontal production interval was drilled and completed barefoot with a unique, rheologically engineered sodium formate drill-in fluid system. The new system, consisting of a sodium formate (NaCOOH) brine as the base fluid and properly sized calcium carbonate as the formation-bridging agent, was selected on the basis of its well-documented record in reducing solids impairment and formation damage in similar sandstone structures in Germany. The system was engineered around the low-shear-rate viscosity (LSRV) concept, designed to provide exceptional rheological properties. After describing the drilling program, the paper gives results on the drilling and completion.

  3. [Preventive measures against health damage due to chemicals in household products].

    PubMed

    Kaniwa, Masa-aki

    2010-01-01

    Chemicals in household products have been paid much attention as the main cause of health damage in consumers, such as allergic contact dermatitis. Preventive measures against health damage due to chemicals in fabrics, plastics and rubber products for household use, are reviewed, focusing on 1) the incidence of health damage due to household products, 2) causative product-chemical investigation, and 3) case studies on skin damage.

  4. The Damage To The Armour Layer Due To Extreme Waves

    NASA Astrophysics Data System (ADS)

    Oztunali Ozbahceci, Berguzar; Ergin, Aysen; Takayama, Tomotsuka

    2010-05-01

    The sea waves are not regular but random and chaotic. In order to understand this randomness, it is common to make individual wave analysis in time domain or spectral analysis in frequency domain. Characteristic wave heights like Hmax, H%2,H1-10, H1-3, Hmean are obtained through individual wave analysis in time domain. These characteristic wave heights are important because they are used in the design of different type of coastal structures. It is common to use significant wave height, H1-3,for the design of rubble mound structures. Therefore, only spectrally derived or zero-crossing significant wave height is usually reported for the rubble mound breakwaters without any information on larger waves. However, even the values of H1-3are similar; some train of irregular waves may exhibit a large fluctuation of instantaneous wave energy, while another train may not show such a fluctuation (Goda, 1998). Moreover, freak or rogue wave, simply defined as the wave exceeding at least twice the significant wave height may also occur. Those larger waves were called as extreme waves in this study and the effect of extreme waves on the damage to the armour layer of rubble mound breakwaters was investigated by means of hydraulic model experiment. Rock armored rubble mound breakwater model with 1:1.5 slope was constructed in the wave channel of Hydraulics Laboratory of the Disaster Prevention Research Institute of Kyoto University, Japan. The model was consisted of a permeable core layer, a filter and armour layer with two stones thicknesses. Size of stones were same for both of the slopes as Dn50(armour)=0.034m, Dn50(filter)=0.021m and Dn50(core)=0.0148m for armour, filter and core layers, respectively. Time series which are approximately equal to 1000 waves, with similar significant wave height but different extreme wave height cases were generated. In order to generate necessary time series in the wave channel, they were firstly computed by numerically. For the numerical

  5. Damage areas due to impact craters on LDEF aluminum panels

    NASA Technical Reports Server (NTRS)

    Coombs, Cassandra R.; Atkinson, Dale R.; Allbrooks, Martha; Wagner, J. D.

    1992-01-01

    spallation zone on the backside, approximately equal in size to that on the front side. Results from this study demonstrate that the impact damaged areas extend far beyond the actual craters in coated or painted surfaces. While the cratering damaged much greater than 1 percent of the total surface area, the total impact damage area exceeded 3 percent.

  6. Damage areas due to impact craters on LDEF aluminum panels

    NASA Astrophysics Data System (ADS)

    Coombs, Cassandra R.; Atkinson, Dale R.; Allbrooks, Martha; Wagner, J. D.

    1992-06-01

    spallation zone on the backside, approximately equal in size to that on the front side. Results from this study demonstrate that the impact damaged areas extend far beyond the actual craters in coated or painted surfaces. While the cratering damaged much greater than 1 percent of the total surface area, the total impact damage area exceeded 3 percent.

  7. Extra lethal damage due to residual incompletely repaired sublethal damage in hyperfractionated and continuous radiation treatment

    SciTech Connect

    Chen, J.; van de Geijn, J.; Goffman, T. )

    1991-05-01

    In the conventional linear--quadratic model of single-dose response, the {alpha} and {beta} terms reflect lethal damage created {ital during} the delivery of a dose, from two different presumed molecular processes, one linear with dose, the other quadratic. With the conventional one-fraction-per-day (or less) regimens, the sublethal damage (SLD), presumably repairing exponentially over time, is essentially completely fixed by the time of the next dose of radiation. If this assumption is true, the effects of subsequent fractions of radiation should be independent, that is, there should be little, if any, reversible damage left from previous fractions, at the time of the next dose. For multiple daily fractions, or for the limiting case, continuous radiation, this simplification may overlook damaged cells that have had insufficient time for repair. A generalized method is presented for accounting for extra lethal damage (ELD) arising from such residual SLD for hyperfractionation and continuous irradiation schemes. It may help to predict differences in toxicity and tumor control, if any, obtained with unconventional'' treatment regimens. A key element in the present model is the finite size and the dynamic character of the pool of sublethal damage. Besides creating the usual linear and quadratic components of lethal damage, each new fraction converts a certain fraction of the existing SLD into ELD, and creates some new SLD.

  8. Intracavity Optical Damage Due To Electrons, Ions And Ultraviolet Photons

    NASA Astrophysics Data System (ADS)

    Haglund, Richard F.

    1988-06-01

    Many of the damage problems experienced by intracavity laser optics, particularly for discharge-pumped and electron-beam-pumped laser systems, arise from the electronic interactions of low-energy electrons, ions and ultraviolet photons with the surface and near-surface regions of the optical material. We shall describe results of recent experiments which display some of the electronic mechanisms involved in these processes, through which incident electronic energy is absorbed, localized, transformed and ultimately dissipated in ways which change the surface composition and electronic structure of model wide bandgap optical materials. We consider discuss recent experimental results on the metallization of dielectric surfaces, the effects of adsorbed overlayers in inhibiting desorption of excited neutral atoms, and the effects of glass processing on response to electron and ion irradiation. We also point out some of the ways in which the changes in the optical surfaces wrought by the low-energy and low-intensity irradiation arising from the laser pumping mechanism can influence thermal, chemical and plasma properties of the surface in ways which alter the surface response to intense laser radiation.

  9. Probabilistic approach to damage of tunnel lining due to fire

    NASA Astrophysics Data System (ADS)

    Šejnoha, Jiří; Sýkora, Jan; Novotná, Eva; Šejnoha, Michal

    2017-09-01

    In this paper, risk is perceived as the probable damage caused by a fire in the tunnel lining. In its first part the traffic flow is described as a Markov chain of joint states consisting of a combination of trucks/buses (TB) and personal cars (PC) from adjoining lanes. The heat release rate is then taken for a measure of the fire power. The intensity λf reflecting the frequency of fires was assessed based on extensive studies carried out in Austria [1] and Italy [2, 3]. The traffic density AADT, the length of the tunnel L, the percentage of TBs, and the number of lanes are the remaining parameters characterizing the traffic flow. In the second part, a special combination of models originally proposed by Bažant and Thonguthai [4], and Künzel & Kiessl [5] for the description of transport processes in concrete at very high temperatures creates a basis for the prediction of the thickness of the spalling zone and the volume of concrete degraded by temperatures that exceed a certain temperature level. The model was validated against a macroscopic test on concrete samples placed into the furnace.

  10. Effects of restraint on expansion due to delayed ettringite formation

    SciTech Connect

    Bouzabata, Hassina; Multon, Stephane; Sellier, Alain; Houari, Hacene

    2012-07-15

    Delayed ettringite formation (DEF) is a chemical reaction that causes expansion in civil engineering structures. The safety level of such damaged structures has to be reassessed. To do this, the mechanical conditions acting on DEF expansions have to be analysed and, in particular, the variation of strength with expansion and the effect of restraint on the DEF expansion. This paper highlights several points: DEF expansion is isotropic in stress-free conditions, compressive stresses decrease DEF expansion in the direction subjected to restraint and lead to cracks parallel to the restraint, and expansion measured in the stress-free direction of restrained specimens is not modified. Thus restraint causes a decrease of the volumetric expansion and DEF expansion under restraint is anisotropic. Moreover, the paper examines the correlation between DEF expansion and concrete damage, providing data that can be used for the quantification of the effect of stresses on DEF induced expansion.

  11. Reducing formation damage through two-stage polymer filtration

    SciTech Connect

    Houchin, L.R.; Hudson, L.M.; Caothien, S.; Daddazio, G.; Hashemi, R.

    1986-01-01

    Formation damage resulting from the use of unfiltered polymers during gravel pack completion operations has been addressed as it relates to HEC completion fluids. However, other filtered polymer systems exhibit properties which, in specific applications, may out perform HEC systems. Thus, the performance characteristics of six commonly used polymer systems, hydroxyethyl cellulose (HEC), clarified xanthan gum (XC), HEC/XC blends, crosslinked carboxymethyl hydroxyethyl cellulose (CMHEC), hydroxypropyl guar (HPG), and standard xanthan gum (XCD), required additional evaluation. Fluid modelling was employed using a new two-stage filtration process (gel filtration) in which the viscosified fluids were optimally sheared and fine-filtered to improve sand placement efficiency and reduce formation damage. The data obtained from this study establishes mixing and filtration design criteria for optimizing completion techniques such as gravel packing, sand washing, polymer diverting, and lost circulation control.

  12. Damages and Expected Deaths Due to Excess NOx Emissions from 2009 to 2015 Volkswagen Diesel Vehicles.

    PubMed

    Holland, Stephen P; Mansur, Erin T; Muller, Nicholas Z; Yates, Andrew J

    2016-02-02

    We estimate the damages and expected deaths in the United States due to excess emissions of NOx from 2009 to 2015 Volkswagen diesel vehicles. Using data on vehicle registrations and a model of pollution transport and valuation, we estimate excess damages of $430 million and 46 excess expected deaths. Accounting for uncertainty about emissions gives a range for damages from $350 million to $500 million, and a range for excess expected deaths from 40 to 52. Our estimates incorporate significant local heterogeneity: for example, Minneapolis has the highest damages despite having fewer noncompliant vehicles than 13 other cities. Our estimated damages greatly exceed possible benefits from reduced CO2 emissions due to increased fuel economy.

  13. [Present status of gastrointestinal damage due to non-steroidal anti-inflammatory drugs (NSAIDs)].

    PubMed

    Inaba, Tomoki; Ishikawa, Shigenao; Miyoshi, Masatsugu; Kurahara, Koichi

    2013-06-01

    Non-steroidal anti-inflammatory drugs (NSAIDs) are roughly divided into a low-dose aspirin group used for primary and secondary prevention of cardiovascular events and non-aspirin NSAIDs used for treatment of bone and joint diseases. Both cause gastrointestinal damage directly or indirectly. In the present study, we reviewed gastrointestinal damage due to non-aspirin NSAIDs with respect to the esophagus, stomach/duodenum, small intestine and colon. Damage due to NSAIDs occurs in all digestive tracts and since the analgesic effect of NSIADs hides subjective symptoms, the symptoms are often not treated until they are advanced to a serious state. Further, patients receiving NSAIDs are mostly elderly and have complications so that the onset of the conditions is serious and prevention is important. It is necessary to investigate a method that is effective for preventing damage for all digestive tracts and the mechanisms of damage must be understood for this reason.

  14. Reducing Mechanical Formation Damage by Minimizing Interfacial Tension and Capillary Pressure in Tight Gas

    NASA Astrophysics Data System (ADS)

    Ahmed, Arshad; Talib Shuker, Muhannad; Rehman, Khalil; Bahrami, Hassan; Memon, Muhammad Khan

    2013-12-01

    Tight gas reservoirs incur problems and significant damage caused by low permeability during drilling, completion, stimulation and production. They require advanced improvement techniques to achieve flow gas at optimum rates. Water blocking damage (phase Trapping/retention of fluids) is a form of mechanical formation damage mechanism, which is caused by filtrate invasion in drilling operations mostly in fracturing. Water blocking has a noticeable impact on formation damage in gas reservoirs which tends to decrease relative permeability near the wellbore. Proper evaluation of damage and the factors which influence its severity is essential to optimize well productivity. Reliable data regarding interfacial tension between gas and water is required in order to minimize mechanical formation damage potential and to optimize gas production. This study was based on the laboratory experiments of interfacial tension by rising drop method between gas-brine, gas-condensate and gas-brine. The results showed gas condensate has low interfacial tension value 6 - 11 dynes/cm when compared to gas-brine and gas- diesel which were 44 - 58 dynes/cm and 14 - 19 dynes/cm respectively. In this way, the capillary pressure of brine-gas system was estimated as 0.488 psi, therefore diesel-gas system was noticed about 0.164 psi and 0.098 psi for condensate-gas system. A forecast model was used by using IFT values to predict the phase trapping which shows less severe phase trapping damage in case of condensate than diesel and brine. A reservoir simulation study was also carried out in order to better understand the effect of hysteresis on well productivity and flow efficiency affected due to water blocking damage in tight gas reservoirs.

  15. Energy Change due to Off-Fault Damage Evolution associated with Dynamic Fault Tip Growth

    NASA Astrophysics Data System (ADS)

    Suzuki, T.

    2010-12-01

    We theoretically study off-fault damage evolution effects on dynamic earthquake rupture, especially from a standpoint of energy change in a whole system. The importance of off-fault inelastic energy loss due to damage on dynamic earthquake rupture has attracted interests of many researchers in terms of, for example, rupture velocity reduction and crack tip growth cessation. The damage effect is found to be important on dynamic earthquake slip behavior in terms of porosity increase also in a series of our previous studies, Suzuki and Yamashita (2007; 2008; 2009; 2010). The mathematical formulation of Murakami and Kamiya (1997) is assumed in the present study; the damage tensor D is used to describe damage state in a medium. Damage, which consists of microcracks in a medium, has direction (defined as normal to the crack surface) and the magnitude (crack size), so that a scalar damage variable is insufficient to describe the damage state. We first analytically derive the equation system including the damage tensor and describing energy change in a whole system due to any dynamic elastic and inelastic deformation processes such as macroscopic crack extension and damage evolution. The change in the summation of strain and kinetic energies and damage energy is found to be equal to the summation of energy flowing out of the medium through the boundary and energy turning to heat and irreversibly lost based on the analytical expression; the damage energy is associated with surface energy released by damage evolution. The damage energy is confirmed to be equal to the summation of the loss in strain energy due to change in the elastic moduli and irreversibly lost energy. A mode III crack embedded in a medium causing damage is then assumed to study the off-fault damage effects on dynamic earthquake rupture. Spontaneous crack tip growth with the Coulomb fracture criterion is assumed and in such a case the rupture velocity can be sufficiently smaller than the terminal velocity

  16. CFD Assessment of Aerodynamic Degradation of a Subsonic Transport Due to Airframe Damage

    NASA Technical Reports Server (NTRS)

    Frink, Neal T.; Pirzadeh, Shahyar Z.; Atkins, Harold L.; Viken, Sally A.; Morrison, Joseph H.

    2010-01-01

    A computational study is presented to assess the utility of two NASA unstructured Navier-Stokes flow solvers for capturing the degradation in static stability and aerodynamic performance of a NASA General Transport Model (GTM) due to airframe damage. The approach is to correlate computational results with a substantial subset of experimental data for the GTM undergoing progressive losses to the wing, vertical tail, and horizontal tail components. The ultimate goal is to advance the probability of inserting computational data into the creation of advanced flight simulation models of damaged subsonic aircraft in order to improve pilot training. Results presented in this paper demonstrate good correlations with slope-derived quantities, such as pitch static margin and static directional stability, and incremental rolling moment due to wing damage. This study further demonstrates that high fidelity Navier-Stokes flow solvers could augment flight simulation models with additional aerodynamic data for various airframe damage scenarios.

  17. Study of damage formation and annealing of implanted III-nitride semiconductors for optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Faye, D. Nd.; Fialho, M.; Magalhães, S.; Alves, E.; Ben Sedrine, N.; Rodrigues, J.; Correia, M. R.; Monteiro, T.; Boćkowski, M.; Hoffmann, V.; Weyers, M.; Lorenz, K.

    2016-07-01

    An n-GaN/n-AlGaN/p-GaN light emitting diode (LED) structure was implanted with Eu ions. High temperature high pressure annealing at 1400 °C efficiently decreases implantation damage and optically activates the Eu ions. However, the electrical properties of the p-n junction deteriorate possibly due to the formation of conducting paths along dislocations during the extreme annealing conditions.

  18. A Study of the Crack Damage in Fuel-Filled Tank Walls Due to Ballistic Penetrators

    DTIC Science & Technology

    1976-03-01

    b----e~ REPORT , DOCUMENTATIONPAGE ____________________ I. ~ ~ ~ ~ ~ ~ ~ lp _MOR aUUE ACESO O3 I TATALOG ŘU01 R A Study of the Crack Damage in Fuel...ates es5 r ~~~Filled Tank’Wa~lls Due to Ballistic ____________ a. PaRPORMIMS 0960. REPORT NUMBS" Steven Lock/Fahrenkrog Naval Postgraduiate School...the accurate prediction of damage to the tank. due to a ball.istic projectile. This report presents a method for predicting the amount of cracking of a

  19. Shunt insufficiency due to knot formation in the peritoneal catheter.

    PubMed

    Fekete, Gábor; Nagy, Andrea; Pataki, István; Bognar, László; Novák, László

    2013-07-30

    The authors report a rare case of the peripheral obstruction of a ventriculoperitoneal shunt. Premature baby was operated on hydrocephalus due to germinal matrix bleeding. After two months of implantation of venticuloperitoneal shunt peripheral insufficiency of the system was emerged. During the shunt revision extensive knot formation became visible. We simply cut the catheter above the knot and the working shunt was replaced into the abdominal cavity. The postoperative course was uneventful and the baby was free of complaints for more than one year. The pathomechanism of knot formation is not clear thus the discovery of the problem during the operation is an unexpected event. In our opinion tight knot cannot be spontaneously formed intraabdominally. Loose knots can be developed and can reduce the capacity of liquor flow. We think that the knot tightens during pulling out. Longer peritoneal catheters can precipitate multiple looping and/or axial torquations and increase the peripheral resistance of the shunt. In such cases when the pulling out is challenged conversion to laparotomy is suggested.

  20. Grain damage, phase mixing and plate-boundary formation

    NASA Astrophysics Data System (ADS)

    Bercovici, David; Skemer, Philip

    2017-07-01

    The generation of plate tectonics on Earth relies on complex mechanisms for shear localization, as well as for the retention and reactivation of weak zones in the cold ductile lithosphere. Pervasive mylonitization, wherein zones of high deformation coincide with extensive mineral grain size reduction, is an important clue to this process. In that regard, the grain-damage model of lithospheric weakening provides a physical framework for both mylonitization and plate generation, and accounts for the competition between grain size reduction by deformation and damage, and healing by grain growth. Zener pinning at the evolving interface between mineral components, such as olivine and pyroxene, plays a key role in helping drive grains to small mylonitic sizes during deformation, and then retards their growth once deformation ceases. The combined effects of damage and pinning, however, rely on the efficiency of inter-grain mixing between phases (e.g., olivine and pyroxene) and grain dispersal, which likely depends on grain size itself. Here we present a new model for inter-grain mixing and damage and the onset of rapid mixing. The model considers the competition between the formation of new grains behind a receding interphase triple junction (e.g., olivine growing into a boundary between two pyroxene grains) and their severance or spalling during progressive deformation and damage. The newly formed grains of one phase are then transported along the opposing phase's grain-boundaries and the two phases become dispersed at the grain-scale in a growing mixed layer. The small intermixed grains also affect the grain evolution of the surrounding host grains by Zener pinning, and hence influence the rheology and growth of the mixed layer. As the grains in the mixed layer shrink, subsequently spalled new grains are also smaller, causing a feedback that leads to more rapid mixing and shear localization in the mixed layer. The early stages of mixing can be compared to laboratory

  1. Characterization of microstructural damage due to low-cycle fatigue by EBSD observation

    SciTech Connect

    Kamaya, Masayuki

    2009-12-15

    Electron backscatter diffraction (EBSD) in conjunction with scanning electron microscopy was used to assess the damage due to cyclic or uniform strain. Samples of Type 316 stainless steel after fatigue and tensile tests were prepared for EBSD observation and the misorientation angle between neighboring points (local misorientation) was evaluated. It was shown that the local misorientation developed due to the cyclic and uniform strain and that its spatial distribution was not uniform. In fatigue samples, the area of large local misorientation tended to form clusters, whereas it localized to the grain boundaries in the tensile samples, and the magnitude of local misorientation and the degree of the localization increased with the strain amplitude. The degree of localization was quantified via statistical processing of the measured data. It was also shown that the source of damage (cyclic or uniform strain) and the loading direction could be deduced from the EBSD observations of the damaged sample.

  2. Changes of color coordinates of biological tissue with superficial skin damage due to mechanical trauma

    NASA Astrophysics Data System (ADS)

    Pteruk, Vail; Mokanyuk, Olexander; Kvaternuk, Olena; Yakenina, Lesya; Kotyra, Andrzej; Romaniuk, Ryszard S.; Dussembayeva, Shynar

    2015-12-01

    Change of color coordinates of normal and pathological biological tissues is based on calculated spectral diffuse reflection. The proposed color coordinates of normal and pathological biological tissues of skin provided using standard light sources, allowing accurately diagnose skin damage due to mechanical trauma with a blunt object for forensic problems.

  3. APPLICABILITY OF A ACCUMULATED DAMAGE PARAMETER METHOD ON SOIL LIQUEFACTION DUE TOSEVERAL EARTHQUAKES

    NASA Astrophysics Data System (ADS)

    Izawa, Jun; Tanoue, Kazuya; Murono, Yoshitaka

    Severe soil liquefaction due to long duration earthquake with low acceleration occurred at Tokyo Bay area in the 2011 off the Pacific coast of Tohoku Earthquake. This phenomenon clearly shows that soil liquefaction is affected by properties of input waves. This paper describes effect of wave properties of earthquake on liquefaction using Effective Stress analysis with some earthquakes. Analytical result showedthat almost the same pore water pressure was observed due to both long durationearthquake with max acceleration of 150Gal and typical inland active fault earthquake with 891Gal. Additionally, lique-faction potentials for each earthquake were evaluated by simple judgment with accumulated damage parameter, which is used for design of railway structuresin Japan. As a result, it was found that accurate liquefaction resistance on large cyclic area is necessaryto evaluate liquefaction potential due to long duration earthquake with low acceleration with simple judgment with accumulated damage parameter.

  4. Formation of amorphous silicon by light ion damage

    SciTech Connect

    Shih, Y.C.

    1985-12-01

    Amorphization by implantation of boron ions (which is the lightest element generally used in I.C. fabrication processes) has been systematically studied for various temperatures, various voltages and various dose rates. Based on theoretical considerations and experimental results, a new amorphization model for light and intermediate mass ion damage is proposed consisting of two stages. The role of interstitial type point defects or clusters in amorphization is emphasized. Due to the higher mobility of interstitials out-diffusion to the surface particularly during amorphization with low energy can be significant. From a review of the idealized amorphous structure, diinterstitial-divacancy pairs are suggested to be the embryos of amorphous zones formed during room temperature implantation. The stacking fault loops found in specimens implanted with boron at room temperature are considered to be the origin of secondary defects formed during annealing.

  5. New perspectives on the damage estimation for buried pipeline systems due to seismic wave propagation

    SciTech Connect

    Pineda Porras, Omar Andrey

    2009-01-01

    Over the past three decades, seismic fragility fonnulations for buried pipeline systems have been developed following two tendencies: the use of earthquake damage scenarios from several pipeline systems to create general pipeline fragility functions; and, the use of damage scenarios from one pipeline system to create specific-system fragility functions. In this paper, the advantages and disadvantages of both tendencies are analyzed and discussed; in addition, a summary of what can be considered the new challenges for developing better pipeline seismic fragility formulations is discussed. The most important conclusion of this paper states that more efforts are needed to improve the estimation of transient ground strain -the main cause of pipeline damage due to seismic wave propagation; with relevant advances in that research field, new and better fragility formulations could be developed.

  6. Time evolution of damage due to environmentally assisted aging in a fiber bundle model

    NASA Astrophysics Data System (ADS)

    Lennartz-Sassinek, S.; Main, I. G.; Danku, Z.; Kun, F.

    2013-09-01

    Damage growth in composite materials is a complex process which is of interest in many fields of science and engineering. We consider this problem in a fiber bundle model where fibers undergo an aging process due to the accumulation of damage driven by the locally acting stress in a chemically active environment. By subjecting the bundle to a constant external load, fibers fail either when the load on them exceeds their individual intrinsic strength or when the accumulated internal damage exceeds a random threshold. We analyze the time evolution of the breaking process under low external loads where aging of fibers dominates. In the mean field limit, we show analytically that the aging system continuously accelerates in a way which can be characterized by an inverse power law of the event rate with a singularity that defines a failure time. The exponent is not universal; it depends on the details of the aging process. For localized load sharing, a more complex damage process emerges which is dominated by distinct spatial regions of the system with different degrees of stress concentration. Analytical calculations revealed that the final acceleration to global failure is preceded by a stationary accumulation of damage. When the disorder is strong, the accelerating phase has the same functional behavior as in the mean field limit. The analytical results are verified by computer simulations.

  7. Observation of earthquake ground motion due to aftershocks of the 2016 Kumamoto earthquake in damaged areas

    NASA Astrophysics Data System (ADS)

    Yamanaka, Hiroaki; Chimoto, Kosuke; Miyake, Hiroe; Tsuno, Seiji; Yamada, Nobuyuki

    2016-12-01

    We have conducted observation of earthquake ground motion due to aftershocks of the 2016 Kumamoto earthquake at 26 temporary stations in damaged areas of Kumamoto city, Mashiki town, Nishihara village and Minami-Aso village (partly in Aso city) in Kumamoto prefecture, Japan. Continuous recordings of ground acceleration were acquired in a period of about 1 month after the occurrence of the main shock on April 16, 2016. This preliminary analysis of the observed records clearly indicates strong effects of local geological condition in the heavily damaged districts in Mashiki town and Nishihara village. Spectral ratios of the ground motions at the stations in the severely damaged districts to those at the reference sites are characterized by large amplitudes at periods of 0.5-1 s. Peak ground velocities and seismic intensities are also large at the sites. Seismic intensities at the stations in the damaged districts are larger by an intensity of one at the maximum than those at the stations with the minor damage. The ground motions at the stations in Kumamoto city are rich in later phases with long duration suggesting basin effects. However, site amplification effects could not clearly be identified at the stations in the Minami-Aso area from the results in the conventional spectral ratio approach.[Figure not available: see fulltext.

  8. Nonstructural damages of reinforced concrete buildings due to 2015 Ranau earthquake

    NASA Astrophysics Data System (ADS)

    Adiyanto, Mohd Irwan; Majid, Taksiah A.; Nazri, Fadzli Mohamed

    2017-07-01

    On 15th June 2016 a moderate earthquake with magnitude Mw5.9 was occurred in Sabah, Malaysia. Specifically, the epicentre was located at 16 km northwest of Ranau. Less than two days after the first event, a reconnaissance mission took action to investigate the damages on buildings. Since the reinforced concrete buildings in Ranau were designed based on gravity and wind load only, a lot of minor to severe damages was occurred. This paper presents the damages on the nonstructural elements of reinforced concrete buildings due to Ranau earthquake. The assessment was conducted via in-situ field investigation covering the visual observation, taking photo, and interview with local resident. Based on in-situ field investigation, there was a lot of damages occurred on the nonstructural elements like the brick walls. Such damages cannot be neglected since it can cause injury and fatality to the victims. Therefore, it can be concluded that the installation of nonstructural elements should be reviewed for the sake of safety.

  9. Attenuation due to hysteretic damage in the free vibration of a beam

    SciTech Connect

    Mendelsohn, Daniel A.; Pecorari, Claudio

    2014-02-18

    We present an asymptotic analysis of nonlinear free vibration of a beam with a damage plane represented by nonlinear hysteretic bending and shear springs. The perturbation parameter is the product of the ratio of the nonlinear to linear parts of the stiffness times the amplitude of the free vibration. The loss of energy and ensuing attenuation due to hysteresis is accounted for by reducing the amplitude of vibration after each cycle by an amount such that the loss in total system energy equals the work done to traverse the hysteresis loop. A new Fourier representation for each cycle of the hysteresis and the deflection solution is used for this purpose and leads to higher harmonics, an evolving complex stiffness and corrected natural frequency that are linked to the attenuation. The frequency increases to its linear value from an initially reduced value. The damage parameter, frequency shift and fundamental amplitudes are presented as functions of the initial damage parameter and time (cycles of vibration). The amplitudes of several of the higher harmonics are also presented as functions of time. Many of the results exhibit sufficient sensitivity with respect to the damage parameter that they should be able to be used to characterize the damage.

  10. What to call spinal cord damage not due to trauma? Implications for literature searching

    PubMed Central

    New, Peter W.; Delafosse, Veronica

    2012-01-01

    Objectives To illustrate the importance of multiple search terms and databases when searching publications on spinal cord damage not due to trauma. To develop comprehensive search filter for this subject, compare the results for 2000–2009 with the Medical Subject Headings (MeSH) and Emtree term ‘spinal cord diseases’ and determine changes in the number of articles over this period. Design Literature searches and search filter development. Setting Australia. Interventions Titles and abstracts searched in MEDLINE and EMBASE (2000–2009) for articles involving humans using search terms ‘non-traumatic spinal cord injury’ and ‘nontraumatic spinal cord injury’ (concise search). Develop comprehensive search filter for ‘spinal cord damage not due to trauma’ and compare the results with the MeSH term ‘spinal cord diseases.’ Outcome measures Annual publications (2000–2009) identified in MEDLINE and EMBASE literature searches. Results Concise search identified 35 articles published during 2000–2009. More publications were identified using the term ‘nontraumatic spinal cord injury’ (n = 20) than ‘non-traumatic spinal cord injury’ (n = 16). Publications increased for both terms ‘spinal cord diseases’ (2000 = 279; 2009 = 415) and ‘spinal cord damage not due to trauma’ identified by the comprehensive search filter (2000 = 1251; 2009 = 1921). Conclusions Concise searches using terms ‘non-traumatic spinal cord injury’ and ‘nontraumatic spinal cord injury’ fail to identify relevant articles unless combinations of terms and databases are used. These are inadequate search terms for a comprehensive search. Further research is needed to validate our comprehensive search filter. An international consensus process is required to establish an agreed term for ‘spinal cord damage not due to trauma.’ PMID:22333497

  11. The distribution of DNA damage is defined by region-specific susceptibility to DNA damage formation rather than repair differences.

    PubMed

    Strand, Janne M; Scheffler, Katja; Bjørås, Magnar; Eide, Lars

    2014-06-01

    The cellular genomes are continuously damaged by reactive oxygen species (ROS) from aerobic processes. The impact of DNA damage depends on the specific site as well as the cellular state. The steady-state level of DNA damage is the net result of continuous formation and subsequent repair, but it is unknown to what extent heterogeneous damage distribution is caused by variations in formation or repair of DNA damage. Here, we used a restriction enzyme/qPCR based method to analyze DNA damage in promoter and coding regions of four nuclear genes: the two house-keeping genes Gadph and Tbp, and the Ndufa9 and Ndufs2 genes encoding mitochondrial complex I subunits, as well as mt-Rnr1 encoded by mitochondrial DNA (mtDNA). The distribution of steady-state levels of damage varied in a site-specific manner. Oxidative stress induced damage in nDNA to a similar extent in promoter and coding regions, and more so in mtDNA. The subsequent removal of damage from nDNA was efficient and comparable with recovery times depending on the initial damage load, while repair of mtDNA was delayed with subsequently slower repair rate. The repair was furthermore found to be independent of transcription or the transcription-coupled repair factor CSB, but dependent on cellular ATP. Our results demonstrate that the capacity to repair DNA is sufficient to remove exogenously induced damage. Thus, we conclude that the heterogeneous steady-state level of DNA damage in promoters and coding regions is caused by site-specific DNA damage/modifications that take place under normal metabolism. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Damage costs due to automotive air pollution and the influence of street canyons

    NASA Astrophysics Data System (ADS)

    Spadaro, Joseph V.; Rabl, Ari

    Using the methodology of the ExternE Project of the European Commission, we have evaluated the damage costs of automotive air pollution by way of two case studies in France: a trip across Paris, and a trip from Paris to Lyon. This methodology involves an analysis of the impact pathways, starting with the emissions (e.g., g/km of particles from tailpipe), followed by local and regional dispersion (e.g., incremental μg/m 3 of particles), calculation of the physical impacts using exposure-response functions (e.g., cases of respiratory hospital admissions), and finally multiplication by unit costs factors (e.g., ? per hospital admission). Damages are aggregated over all affected receptors in Europe. In addition to the local and regional dispersion calculations carried out so far by ExternE, we also consider the increased microscale impacts due to the trapping of pollutants in street canyons, using numerical simulations with the FLUENT software. We have evaluated impacts to human health, agricultural crops and building materials, due to particles, NO x, CO, HC and CO 2. Health impacts, especially reduced life expectancy, dominate in terms of cost. Damages for older cars (before 1997) range from 2 to 41 Euro cents/km, whereas for newer cars (since 1997), the range 1-9 Euro cents/km, and there is continuing progress in reducing the emissions further. In large cities, the particulate emissions of diesel cars lead to the highest damages, exceeding those of gasoline cars by a factor of 7. For cars before 1997 the order of magnitude of the damage costs is comparable to the price of gasoline, and the loss of life expectancy is comparable to that from traffic accidents.

  13. Experimental study on asphaltene adsorption onto formation rock: An approach to asphaltene formation damage prevention

    SciTech Connect

    Piro, G.; Barberis Canonica, L.; Galbariggi, G.; Bertero, L.; Carniani, C.

    1995-12-31

    In this paper, through a comparative study on Static vs Dynamic adsorption of asphaltene onto formation rock, it is reported how, for the particular asphaltene/formation rock system here considered, the Dynamic asphaltene adsorption onto formation rock is a continuous phenomenon by which the quantity of adsorbed asphaltene increases continuously. In the authors` opinion this rather remarkable adsorption behavior may contribute to asphaltene formation damage. In the hypothesis that prevention may represent a more economical approach than removal, in this work is also reported a possible prevention approach based on formation rock treatment by means of specific chemicals more apt than asphaltenes to be adsorbed onto rock. As preliminary demonstration, with the aim at assessing qualitatively the potential of their approach, the authors have pre-treated the rock by means of commercially available asphaltene dispersant and flocculation inhibitors. Albeit the chosen additives are not commercialized on the base of their specific adsorption feature, a prevention effect has been effectively found. Experimental set ups and procedures used as a base for a test able to rank chemicals with respect to their asphaltene adsorption inhibitive effects are also reported.

  14. Asphaltene adsorption onto formation rock: An approach to asphaltene formation damage prevention

    SciTech Connect

    Piro, G.; Canonico, L.B.; Galbariggi, G.; Bertero, L.; Carniani, C.

    1996-08-01

    In this paper, through a comparative study on static vs. dynamic adsorption of asphaltene onto formation rock, the authors report how, for the particular asphaltene/formation rock system considered, the dynamic asphaltene adsorption onto formation rock is a continuous phenomenon by which the quantity of adsorbed asphaltene increases continuously. In their opinion, this rather remarkable adsorption behavior may contribute to asphaltene formation damage. In the hypothesis that prevention may represent a more economical approach than removal, they also report a possible prevention approach based on formation rock treatment by means of specific chemicals more apt than asphaltenes to be adsorbed onto rock. As a preliminary demonstration, with the aim of assessing qualitatively the potential of their approach, they have pretreated the rock with commercially available asphaltene dispersant and flocculation inhibitors. Although the chosen additives are not commercialized on the basis of their specific adsorption feature, a modest prevention effect has been found. Experimental set-ups and procedures used as a base for a test to rank chemicals with respect to their asphaltene adsorption inhibitive effects are also reported.

  15. Damage Characteristics of the Logical Chip Module Due to Plasma Created by Hypervelocity Impacts

    NASA Astrophysics Data System (ADS)

    Tang, Enling; Wu, Jin; Wang, Meng; Zhang, Lijiao; Xiang, Shenghai; Xia, Jin; Liu, Shuhua; He, Liping; Han, Yafei; Xu, Mingyang; Zhang, Shuang; Yuan, Jianfei

    2016-04-01

    To researching the damage characteristics of typical logical chip modules in spacecraft due to plasma generated by hypervelocity impacts, we have established a triple Langmuir probe diagnostic system and a logical chips measurement system, which were used to diagnose plasma characteristic parameters and the logical chip module's logical state changes due to the plasma created by a 7075 aluminum projectile hypervelocity impact on the 2A12 aluminum target. Three sets of experiments were performed with the collision speeds of 2.85 km/s, 3.1 km/s and 2.20 km/s, at the same incident angles of 30 degrees and logical chip module's positions by using a two-stage light gas gun loading system, a plasma characteristic parameters diagnostic system and a logical chip module's logical state measurement system, respectively. Electron temperature and density were measured at given position and azimuth, and damage estimation was performed for the logical chip module by using the data acquisition system. Experimental results showed that temporary damage could be induced on logical chip modules in spacecraft by plasma generated by hypervelocity impacts under the given experimental conditions and the sensors' position and azimuth. supported by National Natural Science Foundation of China (Nos. 10972145, 11272218, 11472178), Program for Liaoning Excellent Talents in University of China (No. LR2013008), Open Foundation of Key Laboratory of Liaoning Weapon Science and Technology, Liaoning Province Talents Engineering Projects of China (No. 2012921044)

  16. Tharsis Formation by Chemical Plume Due to Giant Impact Event

    NASA Astrophysics Data System (ADS)

    Fleck, J.; Weeraratne, D. S.; Olson, P.

    2014-12-01

    Tharsis formed early in the history of Mars, likely during the Noachian but later than the hemispheric crustal dichotomy that it partially overprints (Johnson and Phillips, 2005; Solomon et al., 2005; Wenzel et al., 2004). It has been suggested that the crustal dichotomy may have been formed by a giant impact (Andrews-Hanna et al., 2008; Marinova et al., 2008; Nimmo et al., 2008). Several models have been proposed to explain a localized orogeny, but predict multiple, evenly-spaced plumes or have instability growth and rise times which are longer than Tharsis formation. We use fluid dynamic experiments to model the differentiation process during Mars accretion using low viscosity glucose syrup solutions and an emulsion of liquid gallium for the metal-rich magma ocean and a high viscosity glucose syrup for the mantle. Our experiments demonstrate the formation of metal-silicate diapirs from metal emulsion drops that form a pond at the base of the magma ocean. The diapirs descend through the underlying mantle with trailing conduit of low viscosity silicate material. The silicate material is buoyant and eventually ascends back through the conduit. Remaining emulsion drops that do not adhere with the diapir fall through the conduit, forcing the buoyant molten silicate material to exit the conduit laterally and ascend along a new trajectory. The time elapsed between diapir formation and ascent of the chemical plume in experiments scales with the time between the formation of the crustal dichotomy on Mars and the formation of Tharsis. Our model offers an explanation for the rapid formation of Tharsis on the edge of the crustal dichotomy via a single large upwelling event followed by smaller upwellings producing and the late stages of effusive volcanism observed in the Tharsis region.

  17. Direct participation of DNA in the formation of singlet oxygen and base damage under UVA irradiation.

    PubMed

    Yagura, Teiti; Schuch, André Passaglia; Garcia, Camila Carrião Machado; Rocha, Clarissa Ribeiro Reily; Moreno, Natália Cestari; Angeli, José Pedro Friedmann; Mendes, Davi; Severino, Divinomar; Bianchini Sanchez, Angelica; Di Mascio, Paolo; de Medeiros, Marisa Helena Gennari; Menck, Carlos Frederico Martins

    2017-07-01

    UVA light is hardly absorbed by the DNA molecule, but recent works point to a direct mechanism of DNA lesion by these wavelengths. UVA light also excite endogenous chromophores, which causes DNA damage through ROS. In this study, DNA samples were irradiated with UVA light in different conditions to investigate possible mechanisms involved in the induction of DNA damage. The different types of DNA lesions formed after irradiation were determined through the use of endonucleases, which recognize and cleave sites containing oxidized bases and cyclobutane pyrimidine dimers (CPDs), as well as through antibody recognition. The formation of 8-oxo-7,8-dihydro-2'-deoxyguanine (8-oxodG) was also studied in more detail using electrochemical detection. The results show that high NaCl concentration and concentrated DNA are capable of reducing the induction of CPDs. Moreover, concerning damage caused by oxidative stress, the presence of sodium azide and metal chelators reduce their induction, while deuterated water increases the amounts of oxidized bases, confirming the involvement of singlet oxygen in the generation of these lesions. Curiously, however, high concentrations of DNA also enhanced the formation of oxidized bases, in a reaction that paralleled the increase in the formation of singlet oxygen in the solution. This was interpreted as being due to an intrinsic photosensitization mechanism, depending directly on the DNA molecule to absorb UVA and generate singlet oxygen. Therefore, the DNA molecule itself may act as a chromophore for UVA light, locally producing a damaging agent, which may lead to even greater concerns about the deleterious impact of sunlight. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Characterization of space station multilayer insulation damage due to hypervelocity space debris impact

    NASA Technical Reports Server (NTRS)

    Rule, William Keith

    1990-01-01

    Four main tasks were accomplished. The first three tasks were related to the goal of measuring the degradation of the insulating capabilities of Space Station multilayer insulation (MLI) due to simulated space debris impacts at hypervelocities. The last task was associated with critically reviewing a Boeing document on the fracture characteristics of the Space Station pressure wall when subjected to a simulated hypervelocity space debris impact. In Task 1, a thermal test procedure for impact damaged MLI specimens was written. In Task 2, damaged MLI specimens were prepared. In Task 3, a computer program was written to simulate MLI thermal tests. In Task 4, the author reviewed a Boeing document describing hypervelocity impact testing on biaxially stressed plates.

  19. Mitochondrial Dysfunction Due to Oxidative Mitochondrial DNA Damage Is Reduced through Cooperative Actions of Diverse Proteins

    PubMed Central

    O'Rourke, Thomas W.; Doudican, Nicole A.; Mackereth, Melinda D.; Doetsch, Paul W.; Shadel, Gerald S.

    2002-01-01

    The mitochondrial genome is a significant target of exogenous and endogenous genotoxic agents; however, the determinants that govern this susceptibility and the pathways available to resist mitochondrial DNA (mtDNA) damage are not well characterized. Here we report that oxidative mtDNA damage is elevated in strains lacking Ntg1p, providing the first direct functional evidence that this mitochondrion-localized, base excision repair enzyme functions to protect mtDNA. However, ntg1 null strains did not exhibit a mitochondrial respiration-deficient (petite) phenotype, suggesting that mtDNA damage is negotiated by the cooperative actions of multiple damage resistance pathways. Null mutations in ABF2 or PIF1, two genes implicated in mtDNA maintenance and recombination, exhibit a synthetic-petite phenotype in combination with ntg1 null mutations that is accompanied by enhanced mtDNA point mutagenesis in the corresponding double-mutant strains. This phenotype was partially rescued by malonic acid, indicating that reactive oxygen species generated by the electron transport chain contribute to mitochondrial dysfunction in abf2Δ strains. In contrast, when two other genes involved in mtDNA recombination, CCE1 and NUC1, were inactivated a strong synthetic-petite phenotype was not observed, suggesting that the effects mediated by Abf2p and Pif1p are due to novel activities of these proteins other than recombination. These results document the existence of recombination-independent mechanisms in addition to base excision repair to cope with oxidative mtDNA damage in Saccharomyces cerevisiae. Such systems are likely relevant to those operating in human cells where mtDNA recombination is less prevalent, validating yeast as a model system in which to study these important issues. PMID:12024022

  20. The apparent explosion moment: Inferences of volumetric moment due to source medium damage by underground nuclear explosions

    NASA Astrophysics Data System (ADS)

    Patton, Howard J.; Taylor, Steven R.

    2011-03-01

    Classical explosion source theory relates isotropic seismic moment to the steady state level of the reduced displacement potential. The theoretical isotropic moment for an incompressible source region Mt is proportional to cavity volume Vc created by pressurization of materials around the point of energy release. Source medium damage due to nonlinear deformations caused by the explosion will also induce volume change Vd and radiate seismic waves as volumetric, double-couple, and compensated linear vector dipole (CLVD) body force systems. A new source model is presented where K is a relative measure of moment MCLVD with respect to the net moment from volumetric sources Vc and Vd. K values from moment tensor inversions steadily decrease from ˜2.5 at lower yields to ˜1.0 for the highest-yield shots on Pahute Mesa. A value of 1.0 implies MCLVD = 0 and, by inference, small Vd. We hypothesize that the extent to which damage adds (or subtracts) volumetric moment is controlled by material properties and dynamics of stress wave rebound, shock wave interactions with the free surface, gravitational unloading, and slapdown of spalled near-surface layers. This hypothesis is tested by comparing measurements of isotropic moment ?I with estimates of Mt based on Vc scaling relationships and velocity-density models. The results support the hypothesis and the conclusion that ?I represents the "apparent explosion moment" since it has contributions from direct effects due to cavity formation and indirect effects due to material damage. Implications for yield estimation using ?I are discussed in general and for the North Korean tests.

  1. Transient cnoidal waves explain the formation and geometry of fault damage zones

    NASA Astrophysics Data System (ADS)

    Veveakis, Manolis; Schrank, Christoph

    2017-04-01

    The spatial footprint of a brittle fault is usually dominated by a wide area of deformation bands and fractures surrounding a narrow, highly deformed fault core. This diffuse damage zone relates to the deformation history of a fault, including its seismicity, and has a significant impact on flow and mechanical properties of faulted rock. Here, we propose a new mechanical model for damage-zone formation. It builds on a novel mathematical theory postulating fundamental material instabilities in solids with internal mass transfer associated with volumetric deformation due to elastoviscoplastic p-waves termed cnoidal waves. We show that transient cnoidal waves triggered by fault slip events can explain the characteristic distribution and extent of deformation bands and fractures within natural fault damage zones. Our model suggests that an overpressure wave propagating away from the slipping fault and the material properties of the host rock control damage-zone geometry. Hence, cnoidal-wave theory may open a new chapter for predicting seismicity, material and geometrical properties as well as the location of brittle faults.

  2. Damage evaluation in metal structures subjected to high energy deposition due to particle beams

    NASA Astrophysics Data System (ADS)

    Scapin, Martina; Peroni, Lorenzo; Dallocchio, Alessandro

    2011-07-01

    The unprecedented energy intensities of modern hadron accelerators yield special problems with the materials that are placed close to or into the high intensity beams. The energy stored in a single beam of LHC particle accelerator is equivalent to about 80 kg of TNT explosive, stored in a transverse beam area with a typical value of 0.2 mm×0.2 mm. The materials placed close to the beam are used at, or even beyond, their damage limits. However, it is very difficult to predict structural efficiency and robustness accurately: beam-induced damage for high energy and high intensity occurs in a regime where practical experience does not exist. The interaction between high energy particle beams and metals induces a sudden non uniform temperature increase. This provokes a dynamic response of the structure entailing thermal stress waves and thermally induced vibrations or even the failure of the component. This study is performed in order to estimate the damage on a copper component due to the impact with a 7 TeV proton beam generated by LHC. The case study represents an accidental case consequent to an abnormal release of the beam: the energy delivered on the component is calculated using the FLUKA code and then used as input in the numerical simulations, that are carried out via the FEM code LS-DYNA.

  3. Dynamic maps of UV damage formation and repair for the human genome.

    PubMed

    Hu, Jinchuan; Adebali, Ogun; Adar, Sheera; Sancar, Aziz

    2017-06-27

    Formation and repair of UV-induced DNA damage in human cells are affected by cellular context. To study factors influencing damage formation and repair genome-wide, we developed a highly sensitive single-nucleotide resolution damage mapping method [high-sensitivity damage sequencing (HS-Damage-seq)]. Damage maps of both cyclobutane pyrimidine dimers (CPDs) and pyrimidine-pyrimidone (6-4) photoproducts [(6-4)PPs] from UV-irradiated cellular and naked DNA revealed that the effect of transcription factor binding on bulky adducts formation varies, depending on the specific transcription factor, damage type, and strand. We also generated time-resolved UV damage maps of both CPDs and (6-4)PPs by HS-Damage-seq and compared them to the complementary repair maps of the human genome obtained by excision repair sequencing to gain insight into factors that affect UV-induced DNA damage and repair and ultimately UV carcinogenesis. The combination of the two methods revealed that, whereas UV-induced damage is virtually uniform throughout the genome, repair is affected by chromatin states, transcription, and transcription factor binding, in a manner that depends on the type of DNA damage.

  4. Evaluating the PM damage cost due to urban air pollution and vehicle emissions in Seoul, Korea.

    PubMed

    Lee, Yong Jin; Lim, Young Wook; Yang, Ji Yeon; Kim, Chang Soo; Shin, Young Chul; Shin, Dong Chun

    2011-03-01

    This study evaluated the prospective damage costs of PM(2.5) inhalation. We performed a health risk assessment based on an exposure-response function to estimate the annual population risk in the Seoul metropolitan city, Korea. Also, we estimated a willingness-to-pay (WTP) amount for reducing the mortality rate in order to evaluate a statistical life value. We combined the annual population risk and the value-of-statistical-life to calculate the damage cost estimate. In the health risk assessment, we applied the PM(2.5) relative risk to evaluate the annual population risk. We targeted an exposure population of 5,401,369 persons who were over the age of 30. Using a Monte-Carlo simulation for uncertainty analysis, we estimated that the population risk of PM(2.5) inhalation during a year in Seoul is 2181 premature deaths for acute exposure and 18,510 premature deaths for chronic exposure. The monthly average WTP for 5/1000 mortality reduction over ten years is $20.20 USD (95% C.I: $16.60-24.50) and the implied value-of-statistical-life (VSL) is $485,000 USD (95% C.I: $398,000-588,000). The damage cost estimate due to risk from PM(2.5) inhalation in Seoul is about $1057 million USD per year for acute exposure, and $8972 million USD per year for chronic exposure. It is important to note that this cost estimate does not reflect all health damage cost estimates in this urban area. This recommendation is a model for evaluating a mortality risk reduction and as such we must re-evaluate an integrated application of morbidity risk. Copyright © 2010 Elsevier Ltd. All rights reserved.

  5. Loss of Homologous Recombination or Non-homologous End-joining Leads to Radial Formation Following DNA Interstrand Crosslink Damage

    PubMed Central

    Hanlon Newell, Amy E.; Hemphill, Aaron; Akkari, Yassmine M.N.; Hejna, James; Moses, Robb E.; Olson, Susan B.

    2008-01-01

    High levels of interstrand cross-link damage in mammalian cells cause chromatid breaks and radial formations recognizable by cytogenetic examination. The mechanism of radial formation observed following DNA damage has yet to be determined. Due to recent findings linking homologous recombination and non-homologous end-joining to the action of the Fanconi anemia pathway, we speculated that radials might be the result of defects in either of the pathways of DNA repair. To test this hypothesis, we have investigated the role of homologous recombination proteins RAD51 and RAD52, non-homologous end-joining proteins Ku70 and LIG4, and protein MRE11 in radial formation and cell survival following interstrand crosslink damage with mitomycin C. For the studies we used small inhibitory RNA to deplete the proteins from cells, allowing for evaluation of radial formation and cell survival. In transformed normal human fibroblasts, depletion of these proteins increased interstrand crosslink sensitivity as manifest by decreased cell survival and increased radial formation. These results demonstrate that inactivation of proteins from either of the two separate DNA repair pathways increases cellular sensitivity to interstrand crosslinks, indicating each pathway plays a role in the normal response to interstrand crosslink damage. We can also conclude that homologous recombination or non-homologous end-joining are not required for radial formation, since radials occur with depletion of these pathways. PMID:18758156

  6. Rock species formation due to deep-mantle melting

    NASA Astrophysics Data System (ADS)

    Fomin, Ilya; Tackley, Paul

    2017-04-01

    Melting and melting migration are processes leading to chemically distinct rock species from a homogeneous substrate in the Earth mantle. Iron-rich melts and corresponding rock species are proposed to result from magma ocean progressive crystallization [Labrosse et al., 2007], and modern geophysical models of ULVZ (e.g. [Beuchert & Schmeling, 2013]) discuss their presence at around the CMB today. We perform long-term (tens of millions of years) numerical simulations of the Earth's mantle for a plausible range of CMB temperatures to understands the possibility of melting and it's consequences. Our model of melting is based on experimental data and ab initio simulations. Physical properties (liquid-solid density differences) are adjusted with data of [de Koker et al., 2013; Mosenfelder et al., 2007; Stixrude & Lithgow-Bertelloni, 2011; Thomas & Asimow, 2013]. This model is included in StagYY numerical code (e.g. [Tackley, 2008]) to simulate mass and thermal fluxes within the Earth mantle. Melt segregation (rocks' permeability and velocities) is considered using equations listed in [Abe, 1995; Solomatov, Stevenson, 1993; Martin & Nokes, 1989]. Thermal effects (adiabatic heating and viscous dissipation) are considered. Viscous dissipation term includes Darcy flux term, but omits highly non-linear Brinkman contribution [Nield, 2007]. Modeling predicts formation of melt if temperature at CMB exceeds 4000-4050K. It's segregation and reequilibration results in sufficient volumes of slightly iron-enriched melt lighter than solid counterpart and moving upward. However, it's propagation is strongly controlled by temperature. Partial melting atop the molten layer results in formation of refractory iron-poor restite which delaminates and sink down, so that a layer of iron-depleted material forms underneath the molten layer. Our model applied to homogeneous pyrolitic mantle results in formation of layers of iron-depleted material with average FeO around 4.6 mol.% and iron

  7. Ion transport through macrocapillaries - Oscillations due to charge patch formation

    NASA Astrophysics Data System (ADS)

    Kulkarni, D. D.; Lyle, L. A. M.; Sosolik, C. E.

    2016-09-01

    We present results on ion transport through large bore capillaries (macrocapillaries) that probe both the geometric and ion-guided aspects of this ion delivery mechanism. We have demonstrated that guiding in macrocapillaries exhibits position- and angle-dependent transmission properties which are directly related to the capillary material (either metal or insulator) and geometry. Specifically, we have passed 1 keV Rb+ ions through glass and metal macrocapillaries, and have observed oscillations for the transmitted ion current passing through the insulating capillaries. Straightforward calculations show that these oscillations can be attributed to beam deflections from charge patches that form on the interior walls of the capillary. The absence of these oscillations in the metal capillary data serve as further confirmation of the role of charge patch formation.

  8. Vulnerability Assessment of Housing Damage in the Philippines Due to an Increase Increase in Typhoon Intensity

    NASA Astrophysics Data System (ADS)

    Esteban, Miguel; Stromberg, Per; Gasparatos, Alexandros

    2010-05-01

    south is almost unaffected due to its proximity to the equator. The estimation of the damage shows that the number of houses partially or totally destroyed could increase by up to 58% in certain regions by 2085. The historical damage data shows how the adaptive capacity values of each region given by Yusuf and Herminia (2009) are crucial to the amount of damage recorded. These authors defined this parameter as the degree to which adjustments in practices, processes or structures can moderate or offset potential damage or take advantage of opportunities from climate change. This clearly highlights the importance of mitigation measures to increase the resilience of communities in the future. This is a significant conclusion of the present paper, independent of whether tropical cyclones increase in intensity or not.

  9. Mechanisms of detonation formation due to a temperature gradient

    NASA Astrophysics Data System (ADS)

    Kapila, A. K.; Schwendeman, D. W.; Quirk, J. J.; Hawa, T.

    2002-12-01

    Emergence of a detonation in a homogeneous, exothermically reacting medium can be deemed to occur in two phases. The first phase processes the medium so as to create conditions ripe for the onset of detonation. The actual events leading up to preconditioning may vary from one experiment to the next, but typically, at the end of this stage the medium is hot and in a state of nonuniformity. The second phase consists of the actual formation of the detonation wave via chemico-gasdynamic interactions. This paper considers an idealized medium with simple, rate-sensitive kinetics for which the preconditioned state is modelled as one with an initially prescribed linear gradient of temperature. Accurate and well-resolved numerical computations are carrried out to determine the mode of detonation formation as a function of the size of the initial gradient. For shallow gradients, the result is a decelerating supersonic reaction wave, a weak detonation, whose trajectory is dictated by the initial temperature profile, with only weak intervention from hydrodynamics. If the domain is long enough, or the gradient less shallow, the wave slows down to the Chapman-Jouguet speed and undergoes a swift transition to the ZND structure. For sharp gradients, gasdynamic nonlinearity plays a much stronger role. Now the path to detonation is through an accelerating pulse that runs ahead of the reaction wave and rearranges the induction-time distribution there to one that bears little resemblance to that corresponding to the initial temperature gradient. The pulse amplifies and steepens, transforming itself into a complex consisting of a lead shock, an induction zone, and a following fast deflagration. As the pulse advances, its three constituent entities attain progressively higher levels of mutual coherence, to emerge as a ZND detonation. For initial gradients that are intermediate in size, aspects of both the extreme scenarios appear in the path to detonation. The novel aspect of this study

  10. Damage to apparel layers and underlying tissue due to hand-gun bullets.

    PubMed

    Carr, Debra; Kieser, Jules; Mabbott, Alexander; Mott, Charlotte; Champion, Stephen; Girvan, Elizabeth

    2014-01-01

    Ballistic damage to the clothing of victims of gunshot wounds to the chest can provide useful forensic evidence. Anyone shot in the torso will usually be wearing clothing which will be damaged by the penetrating impact event and can reportedly be the source of some of the debris in the wound. Minimal research has previously been reported regarding the effect of bullets on apparel fabrics and underlying tissue. This paper examines the effect of ammunition (9 mm full metal jacket [FMJ] DM11 A1B2, 8.0 g; and soft point flat nose Remington R357M3, 10.2 g) on clothing layers that cover the torso (T-shirt, T-shirt plus hoodie, T-shirt plus denim jacket) and underlying structures represented by porcine thoracic wall (skin, underlying tissue, ribs). Impacts were recorded using a Phantom V12 high speed camera. Ejected bone debris was collected before wound tracts were dissected and measured; any debris found was recovered for further analysis. Size and mass of bony debris was recorded; fibre debris recovered from the wound and impact damage to fabrics were imaged using scanning electron microscopy (SEM). Remington R357M3 ammunition was characteristically associated with stellate fabric damage; individual fibres were less likely to show mushrooming. In contrast, 9 mm FMJ ammunition resulted in punch-out damage to fabric layers, with mushrooming of individual fibres being more common. Entry wound sizes were similar for both types of ammunition and smaller than the diameter of the bullet that caused them. In this work, the Remington R357M3 ammunition resulted in larger exit wounds due to the bullet construction which mushroomed. That fabric coverings did not affect the amount of bony debris produced is interesting, particularly given there was some evidence that apparel layers affected the size of the wound. Recent work has suggested that denim (representative of jeans) can exacerbate wounding caused by high-velocity bullet impacts to the thigh when the bullet does not

  11. Jet Formation in Solar Atmosphere due to Magnetic Reconnection

    NASA Astrophysics Data System (ADS)

    González-Avilés, J. J.; Guzmán, F. S.; Fedun, V.

    2017-02-01

    Using numerical simulations, we show that jets with features of type II spicules and cool coronal jets corresponding to temperatures of 104 K can be formed as a result of magnetic reconnection in a scenario with magnetic resistivity. For this, we model the low chromosphere–corona region using the C7 equilibrium solar atmosphere model, assuming that resistive MHD rules the dynamics of the plasma. The magnetic field configurations we analyze correspond to two neighboring loops with opposite polarity. The formation of a high-speed and sharp structure depends on the separation of the loops’ feet. We analyze the cases where the magnetic field strength of the two loops is equal and different. In the first case, with a symmetric configuration the jets rise vertically, whereas in an asymmetric configuration the structure shows an inclination. With a number of simulations carried out under a 2.5D approach, we explore various properties of the excited jets, namely, inclination, lifetime, and velocity. The parameter space involves a magnetic field strength between 20 and 40 G, and the resistivity is assumed to be uniform with a constant value of the order {10}-2{{Ω }}\\cdot m.

  12. Noise due to tip vortex formation on lifting rotors

    NASA Technical Reports Server (NTRS)

    George, A. R.; Najjar, F. E.; Kim, Y. N.

    1980-01-01

    The high frequency broadband noise radiated by the local separated flow at rotor blade tips is analyzed. The aeroacoustic model is based on the convection of the tip region's separated flow pressure fluctuations past the trailing edge of the blade. The tip vortex formation and separation are modeled from available experimental studies. The separated flow pressure fluctuations are estimated using available separated flow experimental data and correlations. The trailing edge noise was approximated using a point dipole model. The point dipole strengths were evaluated by a method based on the trailing edge noise theory of Amiet. The point dipole approach compares favorably to stationary airfoil trailing edge noise analyses and experiments except near the plane of the airfoil. The rotor tip separation noise results are compared to other noise mechanism calculations and to experiments. The tip noise mechanism is shown to be quite important in the high frequency range. It is likely to be the major contributor to high frequency broadband noise for heavily loaded rotors with low turbulence inflow.

  13. Pattern formation due to non-linear vortex diffusion

    NASA Astrophysics Data System (ADS)

    Wijngaarden, Rinke J.; Surdeanu, R.; Huijbregtse, J. M.; Rector, J. H.; Dam, B.; Einfeld, J.; Wördenweber, R.; Griessen, R.

    Penetration of magnetic flux in YBa 2Cu 3O 7 superconducting thin films in an external magnetic field is visualized using a magneto-optic technique. A variety of flux patterns due to non-linear vortex diffusion is observed: (1) Roughening of the flux front with scaling exponents identical to those observed in burning paper including two distinct regimes where respectively spatial disorder and temporal disorder dominate. In the latter regime Kardar-Parisi-Zhang behavior is found. (2) Fractal penetration of flux with Hausdorff dimension depending on the critical current anisotropy. (3) Penetration as ‘flux-rivers’. (4) The occurrence of commensurate and incommensurate channels in films with anti-dots as predicted in numerical simulations by Reichhardt, Olson and Nori. It is shown that most of the observed behavior is related to the non-linear diffusion of vortices by comparison with simulations of the non-linear diffusion equation appropriate for vortices.

  14. Surface damage of metallic implants due to mechanical loading and chemical reactions

    NASA Astrophysics Data System (ADS)

    Ryu, Jaejoong

    The present study investigates interfacial damage mechanism of modular implants due to synergetic action of mechanical contact loading and corrosion. Modular implants are manufactured such that surfaces have a characteristic degree of roughness determined by tool tip size and motion of tool path or feeding speed. The central hypothesis for this work is that during contact loading of metallic implants, mechanisms of damage and dissolution are determined by contact loads, plastic deformation, residual stresses and environmental conditions at the nanoscale surface asperities; while during subsequent rest periods, mechanism of metallic dissolution is determined by the environmental conditions and residual stress field induced due to long range elastic interactions of the plastically deformed asperities. First part of the thesis is focused on investigating the mechanisms underlying surface roughness evolution due to stress-assisted dissolution during the rest period. The latter part is focused on investigating material removal mechanisms during single asperity contact of implant surfaces. Experimental study was performed to elucidate the roughness evolution mechanism by combined effect of multi-asperity contact and environmental corrosion. Cobalt-chromium-molybdenum specimen was subjected to either contact loading alone or alternating contact loading and exposure to reactive environment. Roughness of the specimen surface was monitored by optical profilometry and Fast Fourier Transform (FFT) calculation was used to characterize the evolving behavior of roughness modes. Finite element analysis (FEA) was employed to identify influences of surface morphological configurations and contact pressures on the residual stress development. Analytical model of multi-asperity contact has been developed for prediction of residual stress field for different roughness configurations during varying magnitude of contact loads based on elastic inclusion theory. Experimental results

  15. Mesoscopic structure formation in condensed matter due to vacuum fluctuations

    NASA Astrophysics Data System (ADS)

    Sen, Siddhartha; Gupta, Kumar S.; Coey, J. M. D.

    2015-10-01

    An observable influence of zero-point fluctuations of the vacuum electromagnetic field on bound electrons is well known in the hydrogen atom, where it produces the Lamb shift. Here, we adapt an approach used to explain the Lamb shift in terms of a slight expansion of the orbits due to interaction with the zero-point field and apply it to assemblies of N electrons that are modeled as independent atomically bound two-level systems. The effect is to stabilize a collective ground-state energy, which leads to a prediction of novel effects at room temperature for quasi-two-dimensional systems over a range of parameters in the model, namely, N , the two-level excitation energy ℏ ω and the ionization energy ℏ ω +ɛ . Some mesoscopic systems where these effects may be observable include water sheaths on protein or DNA, surfaces of gaseous nanobubbles, and the magnetic response of inhomogeneous, electronically dilute oxides. No such effects are envisaged for uniform three-dimensional systems.

  16. Periodic fluctuations in deep water formation due to sea ice

    NASA Astrophysics Data System (ADS)

    Saha, R.

    2012-12-01

    During the last ice age, several abrupt warming events took place, known as Dansgaard-Oeschger (D-O) events. Their effects were felt globally, although the North Atlantic experienced the largest temperature increase. The leading hypothesis to explain their occurrence postulates that the warming was caused by abrupt disruptions of the North Atlantic Current due to meltwater discharge from destabilized ice sheets (Heinrich events). However, the number of warming events outnumber the those of ice-sheet collapse. Thus, the majority of D-O events are not attributed to surface freshwater anomalies, and the underlying mechanism behind their occurrence remain unexplained. Using a simple dynamical model of sea ice and an overturning circulation, I show the existence of self-sustained relaxation oscillations in the overturning circulation. The insulating effect of sea ice is shown to paradoxically lead to a net loss of heat from the top layer of the polar ocean when sea ice retreats. Repeated heat loss results in a denser top layer and a destabilized water column, which triggers convection. The convective state pulls the system out of its preferred mode of circulation, setting up relaxation oscillations. The period of oscillations in this case is linked to the geometry of the ocean basin, if solar forcing is assumed to remain constant. If appropriate glacial freshwater forcing is applied to the model, a pattern of oscillation is produced that bears remarkable similarity to the observed fluctuations in North Atlantic climate between 50,000 and 30,000 years before present.; Comparison of NGRIP δ 18-O (proxy for near surface air temperature) between 50,000 and 30,000 years before present, showing Bond cycles (left) with the model output when forced with appropriate glacial freshwater forcing (right).

  17. Mechanical Properties and Elastic Constants Due to Damage Accumulation and Amorphization in SiC

    SciTech Connect

    Gao, Fei; Weber, William J.

    2004-06-28

    Damage accumulation due to cascade overlap, which was simulated previously, has been used to study the changes of elastic constants, bulk and elastic moduli as a function of dose. These mechanical properties generally decrease with increasing dose, and the rapid decrease at low-dose level indicates that point defects and small clusters play an important role in the changes of elastic constants rather than topological disorder. The internal strain relaxation has no effect on the elastic constants, C11 and C12, in perfect SiC, but it has a significant influence on all elastic constants calculated in damaged SiC. The elastic constants in the cascade-amorphized (CA) SiC decrease about 19%, 29% and 46% for C11, C12 and C44, respectively. The bulk modulus decrease 23% and the elastic modulus decreases 29%, which is consistent with experimental measurements. The stability of both the perfect SiC and CA-SiC under hydrostatic tension has been also investigated. All mechanical properties in the CA-SiC exhibit behavior similar to that in perfect SiC, but the critical stress at which the CA-SiC becomes structurally unstable is one order of magnitude smaller than that for perfect SiC.

  18. Evolution of damage fraction due to dense ionizing irradiation on TiO2 film

    NASA Astrophysics Data System (ADS)

    Kumar, Avesh; Kanjilal, D.; Mohanty, T.

    2013-10-01

    The evolution of damage fraction during dense ionizing irradiation at various fluences using 100 MeV Ag ion is studied. Irradiation induced modification of surface roughness and surface potential of titanium dioxide nanocrystalline thin films are estimated. TiO2 thin films deposited on Si (1 0 0) substrate were irradiated by 100 MeV Ag ion beam with varying fluences. Ion bombardment generates point and extended defects in TiO2 thin films due to dense electronic excitation. The surface morphology and surface roughness of irradiated and pristine thin films were measured using atomic force microscopy. The changes in surface potential of pristine as well as Ag ion beam irradiated thin films were measured from contact potential difference between TiO2 thin film (one electrode) of unknown work function and Au (reference electrode) of known work function using scanning Kelvin probe microscopy. The defect size and damage fraction are calculated from exponential fitting of variation of both contact surface potential difference and roughness exponent with fluence.

  19. Myelinosome formation represents an early stage of oligodendrocyte damage in multiple sclerosis and its animal model

    PubMed Central

    Romanelli, Elisa; Merkler, Doron; Mezydlo, Aleksandra; Weil, Marie-Theres; Weber, Martin S.; Nikić, Ivana; Potz, Stephanie; Meinl, Edgar; Matznick, Florian E. H.; Kreutzfeldt, Mario; Ghanem, Alexander; Conzelmann, Karl-Klaus; Metz, Imke; Brück, Wolfgang; Routh, Matthew; Simons, Mikael; Bishop, Derron; Misgeld, Thomas; Kerschensteiner, Martin

    2016-01-01

    Oligodendrocyte damage is a central event in the pathogenesis of the common neuroinflammatory condition, multiple sclerosis (MS). Where and how oligodendrocyte damage is initiated in MS is not completely understood. Here, we use a combination of light and electron microscopy techniques to provide a dynamic and highly resolved view of oligodendrocyte damage in neuroinflammatory lesions. We show that both in MS and in its animal model structural damage is initiated at the myelin sheaths and only later spreads to the oligodendrocyte cell body. Early myelin damage itself is characterized by the formation of local myelin out-foldings—‘myelinosomes'—, which are surrounded by phagocyte processes and promoted in their formation by anti-myelin antibodies and complement. The presence of myelinosomes in actively demyelinating MS lesions suggests that oligodendrocyte damage follows a similar pattern in the human disease, where targeting demyelination by therapeutic interventions remains a major open challenge. PMID:27848954

  20. Damage in Monolithic Thin-Film Photovoltaic Modules Due to Partial Shade

    SciTech Connect

    Silverman, Timothy J.; Mansfield, Lorelle; Repins, Ingrid; Kurtz, Sarah

    2016-09-01

    The typical configuration of monolithic thin-film photovoltaic modules makes it possible for partial shade to place one or more cells in such a module in reverse bias. Reverse bias operation leads to high voltage, current density, and power density conditions, which can act as driving forces for failure. We showed that a brief outdoor shadow event can cause a 7% permanent loss in power. We applied an indoor partial shade durability test that moves beyond the standard hot spot endurance test by using more realistic mask and bias conditions and by carefully quantifying the permanent change in performance due to the stress. With the addition of a pass criterion based on change in maximum power, this procedure will soon be proposed as a part of the module-type qualification test. All six commercial copper indium gallium diselenide and cadmium telluride modules we tested experienced permanent damage due to the indoor partial shade test, ranging from 4% to 14% loss in maximum power. We conclude by summarizing ways to mitigate partial shade stress at the cell, module, and system levels.

  1. Defective motion processing in children with cerebral visual impairment due to periventricular white matter damage.

    PubMed

    Weinstein, Joel M; Gilmore, Rick O; Shaikh, Sumera M; Kunselman, Allen R; Trescher, William V; Tashima, Lauren M; Boltz, Marianne E; McAuliffe, Matthew B; Cheung, Albert; Fesi, Jeremy D

    2012-07-01

    We sought to characterize visual motion processing in children with cerebral visual impairment (CVI) due to periventricular white matter damage caused by either hydrocephalus (eight individuals) or periventricular leukomalacia (PVL) associated with prematurity (11 individuals). Using steady-state visually evoked potentials (ssVEP), we measured cortical activity related to motion processing for two distinct types of visual stimuli: 'local' motion patterns thought to activate mainly primary visual cortex (V1), and 'global' or coherent patterns thought to activate higher cortical visual association areas (V3, V5, etc.). We studied three groups of children: (1) 19 children with CVI (mean age 9y 6mo [SD 3y 8mo]; 9 male; 10 female); (2) 40 neurologically and visually normal comparison children (mean age 9y 6mo [SD 3y 1mo]; 18 male; 22 female); and (3) because strabismus and amblyopia are common in children with CVI, a group of 41 children without neurological problems who had visual deficits due to amblyopia and/or strabismus (mean age 7y 8mo [SD 2y 8mo]; 28 male; 13 female). We found that the processing of global as opposed to local motion was preferentially impaired in individuals with CVI, especially for slower target velocities (p=0.028). Motion processing is impaired in children with CVI. ssVEP may provide useful and objective information about the development of higher visual function in children at risk for CVI. © The Authors. Journal compilation © Mac Keith Press 2011.

  2. Clusters of DNA damage induced by ionizing radiation: Formation of short DNA fragments. I. Theoretical modeling

    SciTech Connect

    Holley, W.R.; Chatterjee, A.

    1996-02-01

    We have developed a general theoretical model for the interaction of ionizing radiation with chromatin. Chromatin is modeled as a 30-nm-diameter solenoidal fiber composed of 20 turns of nucleosomes, 6 nucleosomes per turn. Charged-particle tracks are modeled by partitioning the energy deposition between primary track core, resulting from glancing collisions with 100 eV or less per event, and {delta} rays due to knock-on collisions involving energy transfers > 100 eV. A Monte Carlo simulation incorporates damages due to the following molecular mechanisms: (1) ionization of water molecules leading to the formation of {circ}OH, {circ}H, e{sub aq}, etc.; {circ}OH attack on sugar molecules leading to strand breaks; {circ}OH attack on bases; direct ionization of the sugar molecules leading to strand breaks; direct ionization of the bases. Our calculations predict significant clustering of damage both locally, over regions up to 40 hp and over regions extending to several kilobase pairs. A characteristic feature of the regional damage predicted by our model is the production of short fragments of DNA associated with multiple nearby strand breaks. Such fragments have subsequently been detected experimentally and are reported in an accompanying paper after exposure to both high- and low-LET radiation. The overall measured yields agree well quantitatively with the theoretical predictions. Our theoretical results predict the existence of a strong peak at about 85 bp, which represents the revolution period about the nucleosome. Other peaks at multiples of about 1,000 bp correspond to the periodicity of the particular solenoid model of chromatin used in these calculations. Theoretical results in combination with experimental data on fragmentation spectra may help determine the consensus or average structure of the chromatin fibers in mammalian DNA. 27 refs., 7 figs.

  3. The effect of solids concentration and formation characteristics on formation damage and permeability recovery

    SciTech Connect

    Ismail, A.R.; Arshad, A.M.; Peden, J.M.

    1994-12-31

    An experimental study has been made to investigate the effect of solids concentration and filter media on fluid loss and permeability recovery of cores. KCl-polymer muds of different barite concentrations and different types of core were used to perform the tests. Filtration tests showed that fluid loss increased as solids concentration in the mud increased. Increasing the solids concentration in the mud appears to improve permeability recovery when the cores were backflushed. However, high spurt loss and poor permeability recovery were observed if muds containing polymer materials were used without the addition of solid particles. Filtration and permeability restoration are not only affected by the size, shape and solids concentration in the mud but also to the pore size distribution and core characteristics. Detailed observation using scanning electron microscope was used to identify the solids impairment at the core face. Therefore, to reduce formation damage and improve recovery, suitable size, shape and concentration of solids in the mud must be properly selected.

  4. Partial interruption of axonal transport due to microtubule breakage accounts for the formation of periodic varicosities after traumatic axonal injury.

    PubMed

    Tang-Schomer, Min D; Johnson, Victoria E; Baas, Peter W; Stewart, William; Smith, Douglas H

    2012-01-01

    Due to their viscoelastic nature, white matter axons are susceptible to damage by high strain rates produced during traumatic brain injury (TBI). Indeed, diffuse axonal injury (DAI) is one of the most common features of TBI, characterized by the hallmark pathological profiles of axonal bulbs at disconnected terminal ends of axons and periodic swellings along axons, known as "varicosities." Although transport interruption underlies axonal bulb formation, it is unclear how varicosities arise, with multiple sites accumulating transported materials along one axon. Recently, axonal microtubules have been found to physically break during dynamic stretch injury of cortical axons in vitro. Here, the same in vitro model was used in parallel with histopathological analyses of human brains acquired acutely following TBI to examine the potential role of mechanical microtubule damage in varicosity formation post-trauma. Transmission electron microscopy (TEM) following in vitro stretch injury revealed periodic breaks of individual microtubules along axons that regionally corresponded with undulations in axon morphology. However, typically less than a third of microtubules were broken in any region of an axon. Within hours, these sites of microtubule breaks evolved into periodic swellings. This suggests axonal transport may be halted along one broken microtubule, yet can proceed through the same region via other intact microtubules. Similar axonal undulations and varicosities were observed following TBI in humans, suggesting primary microtubule failure may also be a feature of DAI. These data indicate a novel mechanism of mechanical microtubule damage leading to partial transport interruption and varicosity formation in traumatic axonal injury.

  5. Experimental and theoretical modeling of shrinkage damage formation in fiber composites

    NASA Astrophysics Data System (ADS)

    Korotkov, V. N.; Rozenberg, B. A.

    1998-03-01

    The cure of a thermoset matrix in the formation of composites is always accompanied by chemical shrinkage that generates internal stresses. In composites with high fiber content, the matrix is cured under three-dimensionally constrained conditions. The results of the previous experimental and theoretical modeling of formation of shrinkage damage under these conditions in epoxy-amine systems are briefly discussed. The effect of the model geometry (tube and plate models), scale factor, cure schedule, and chemical structure of composites is analyzed. A theoretical model for predicting the possibility of formation of shrinkage damage in fiber composites is proposed. A regular square structure was considered. Analysis showed that the maximum level of shrinkage stress in the matrix at the ultimate fiber fraction ϕ+ was close to the stress level σ+ in an experimental long tube model, where the formation of shrinkage damage took place. The experimental results for the short tube model showed that the shrinkage damage in epoxy-amine systems occurred up to approximately σ+/3. The damage development took place within the whole range of fiber content from ϕ+ to ϕ* (where the shrinkage stress level was about σ+/3). In the long tube model, cohesive defects always nucleated inside the matrix. The damage grew, reached the inner surface of the tube, and then extended as adhesive debondings. A similar situation is expected in composites with a high fiber content. The damage considered is local, and the total monolithic character of a composite product is conserved.

  6. Damage formation mechanisms of Si and Ge substrates by ion bombardment

    NASA Astrophysics Data System (ADS)

    Matsukuma, Masaaki; Morimoto, Tamotsu; Isobe, Michiro; Karahashi, Kazuhiro; Hamaguchi, Satoshi

    2015-09-01

    Recently the choice of materials for most advanced semiconductor devices, which typically have three dimensional (3D) structures rather than planer ones, has been changing from silicon to III-V compounds or germanium. Such changes have brought renewed interest in physical damages caused by ion bombardment because, in typical gate etching processes of 3D devices, the channel surfaces are exposed directly to the ion irradiation from the plasma. The angles of ion incidence on 3D device gates can be much larger than those on 2D planer devices. Therefore a better control of the damage layer formation on modern 3D devices requires a better understanding of the damage formation mechanisms on such new materials and structures. In this study, damage formation processes by energetic ion bombardment have been simulated for Si/Ge/SiGe substrates by molecular dynamics (MD) simulations and dependence of ion induced damages on species of incident ions and their doses has been examined. Based on the simulations results, damage formation mechanisms will be discussed and a semi-analytical model to predict the damage extent formed by ion bombardment will be also presented.

  7. Damage assessment through changes in mode shapes due to non-proportional damping

    NASA Astrophysics Data System (ADS)

    Iezzi, F.; Spina, D.; Valente, C.

    2015-07-01

    Modal parameters are often used for the structural damage assessment in the dynamic field. Usually, the changes in the modal parameters between different states are assumed as measures of damage. The frequencies are easy to identify, but in some circumstances they are not sensitive to damage and moreover they are mainly a global measure. On the contrary, the mode shapes are more suited for damage localization, but they are generally hard to identify accurately. The energy dissipation, and hence the damping, increases with damage. This feature is stable and has a monotonic behaviour, therefore, damping can be confidently used as an alternative or complementary measure for damage assessment in spite of the accuracy of its identification. However, the damping by itself suffers of the same drawbacks as the frequencies. The joint use of damping and mode shapes is an effective procedure for the damage identification. In the real world the damping is of nonproportional type and the measured mode shapes are complex. It is assumed that an increase of damage causes a modification of non-proportional damping and a variation of the modal complexity. The extent of modal complexity between two different structural states can be used to identify the damage through appropriate indicators. A number of such indicators is introduced and discussed. The effectiveness and sensitivity of the damage indicators are tested on theoretical and pseudo-experimental data.

  8. Damage formation and annealing at low temperatures in ion implanted ZnO

    SciTech Connect

    Lorenz, K.; Alves, E.; Wendler, E.; Bilani, O.; Wesch, W.; Hayes, M.

    2005-11-07

    N, Ar, and Er ions were implanted into ZnO at 15 K within a large fluence range. The Rutherford backscattering technique in the channeling mode was used to study in situ the damage built-up in the Zn sublattice at 15 K. Several stages in the damage formation were observed. From the linear increase of the damage for low implantation fluences, an upper limit of the Zn displacement energy of 65 eV could be estimated for [0001] oriented ZnO. Annealing measurements below room temperature show a significant recovery of the lattice starting at temperatures between 80 and 130 K for a sample implanted with low Er fluence. Samples with higher damage levels do not reveal any damage recovery up to room temperature, pointing to the formation of stable defect complexes.

  9. Estimated crop yield losses due to surface ozone exposure and economic damage in India.

    PubMed

    Debaje, S B

    2014-06-01

    In this study, we estimate yield losses and economic damage of two major crops (winter wheat and rabi rice) due to surface ozone (O3) exposure using hourly O3 concentrations for the period 2002-2007 in India. This study estimates crop yield losses according to two indices of O3 exposure: 7-h seasonal daytime (0900-1600 hours) mean measured O3 concentration (M7) and AOT40 (accumulation exposure of O3 concentration over a threshold of 40 parts per billion by volume during daylight hours (0700-1800 hours), established by field studies. Our results indicate that relative yield loss from 5 to 11% (6-30%) for winter wheat and 3-6% (9-16%) for rabi rice using M7 (AOT40) index of the mean total winter wheat 81 million metric tons (Mt) and rabi rice 12 Mt production per year for the period 2002-2007. The estimated mean crop production loss (CPL) for winter wheat are from 9 to 29 Mt, account for economic cost loss was from 1,222 to 4,091 million US$ annually. Similarly, the mean CPL for rabi rice are from 0.64 to 2.1 Mt, worth 86-276 million US$. Our calculated winter wheat and rabi rice losses agree well with previous results, providing the further evidence that large crop yield losses occurring in India due to current O3 concentration and further elevated O3 concentration in future may pose threat to food security.

  10. Finite element analysis of cornea thermal damage due to pulse incidental far IR laser.

    PubMed

    Shibib, Khalid Salem

    2013-05-01

    Due to the wide use of laser systems in human activities, an accidental event of laser exposure may occur where the most susceptible part to injury is the eye. A typical invisible pulsed, far IR, CO2 laser beam was used as an intrabeam accidentally struck an eye leading to raise its temperature to a limit where a pain sensation was started followed by aversion response with a delay of 0.25 s. At this time, the laser beam was assumed to terminate with respect to the cornea. The finite element method (FEM) was used successfully to predict, numerically, the temperature distribution through the anterior part of the eye when subjected to the laser beam. The FEM program was written using Visual Basic 6 coding. The effects of laser parameters such as laser beam profile, pulse width, and repetition rate on the temperature distribution and the consequential thermal damage were studied. The efficiency of the constructed computer program of the present work was examined by the comparison of the predicted results with those obtained from previously published experimental and theoretical works. The comparison shows good agreements.

  11. Lamb wave interaction at debondings due to impact damage in complex stiffened CFRP structures

    NASA Astrophysics Data System (ADS)

    Eckstein, B.; Moix Bonet, M.; Bach, M.; Fritzen, C.-P.

    2017-04-01

    The increasing usage of Carbon Fiber Reinforced Plastics (CFRP) for primary aerospace structures involves dealing with the principal susceptibility of composite laminates to impact loads as well as the occurrence of barely visible impact damages. One special case among the variety of impact sources is the so called blunt impact, which may cause primarily damage to the internal structure. Thus, the assessment of debonding of stiffening elements in CFRP structures poses an attractive application case for Structural Health Monitoring by Guided Ultrasonic Waves. Wave propagation phenomena at impact damages as well as the utilized signal processing to extract a damage related feature (i.e. damage index) contribute to the sensitivity and thus to the reliability of SHM systems. This work is based on data from the EU-funded project SARISTU, where a generic CFRP door surrounding fuselage panel with an integrated sensor network has been built and tested by introducing a large number of impact damages. Wave interaction of stringer debondings of different size and morphology in omega-stringer stiffened structures are examined to highlight the factors contributing to the sensitivity. Common damage indicator formulations for use with imaging algorithms, such as the Reconstruction Algorithm for the Probabilistic Inspection of Damage (RAPID), are applied on data from various damage cases. Furthermore, the difference in detectability of debondings and delaminations as well as the implications on imaging algorithms are examined.

  12. Cell damage extent due to irradiation with nanosecond laser pulses under cell culturing medium and dry environment

    NASA Astrophysics Data System (ADS)

    Pérez-Gutiérrez, Francisco G.; Guillen, Gabriel; Evans, Rodger; Camacho-López, Santiago; Aguilar, Guillermo

    2009-02-01

    Cell mono-layers were irradiated with nanosecond laser pulses under two distinct scenarios: (a) with culturing medium positioning the beam waist at different stand-off distances γ and (b) without cell culturing medium, positioning the beam waist directly on top of the cell mono-layer. Damaged cells were marked with Trypan Blue, a vital cell marker. Three different zones of damage were identified: (1) a zone of complete cell clearance, surrounded by (2) a ring of dead cells marked with Trypan Blue and (3) the rest of the cell culture where the cells remain alive and viable. Different hydrodynamic mechanisms damage cells as it was shown by high speed video for γ=0 and comparison with time resolved imaging. The cell damage mechanism has its origin on the optical breakdown plasma formation. For the case with culturing medium, a combination of plasma formation and shear stresses are responsible for cell damage; wheras for the case without cell culturing medium, the plasma formation is the only mechanism of interaction between laser pulses and cells. The rapidly expanding plasma generates shock waves whose pressure is most likely responsible for the cell detachment observed.

  13. Radiation damage in silicon due to albedo neutrons emitted from hadronic beam dumps (Fe and U)

    SciTech Connect

    Gabriel, T.A.; Bishop, B.L.

    1987-01-01

    Calculations have been carried out to determine the level of radiation damage that can be expected from albedo neutrons when 1- and 5-GeV negative pions are incident on iron and uranium beam dumps. The calculated damage data are presented in several ways including neutron fluence above 0.111 MeV, 1 MeV equivalent neutron fluence, damage energy deposition, and DPA or displacements per atom. Details are presented as to the method of calculation. 14 refs., 1 fig., 1 tab.

  14. Geochemical modeling of scale formation, and formation damage during production from sulfate and carbonate mineral-bearing reservoirs

    SciTech Connect

    Macgowan, D.B.; Dunn, T.L.; Surdam, R.C. )

    1991-03-01

    The physical and chemical processes that affect reservoir fluids during production can be modeled by methodologies similar to those used for modeling clastic diagenesis. That these processes may result in formation damage and scale formation make them of interest to production geologists and engineers. Pathway modeling, based upon a series of critical divides, predicts which reactions are likely to occur between formation, production tubing, and reservoir fluids. Thermodynamic equilibria modeling calculates direction and magnitude of possible reactions. Integration of these approaches with observations of patterns of scale formation, production line, and formation damage yield a model capable of predicting the magnitude and direction of reactions that may produce negative impacts on reservoir production. Critical divides characterizing these processes in carbonate and sulfate mineral-bearing reservoirs include: (1) presence or absence of sulfate-bearing minerals within the production volume; (2) presence of iron within production line or formation; (3) ratio of concentration of bicarbonate to hydrogen sulfide; (4) capacity of aqueous and solid phases to buffer formation fluid pH; and (5) magnitude of pressure and temperature drops during production. The model qualitatively predicts: (1) likelihood of sulfide, sulfate, or carbonate mineral precipitation during production; (2) souring of the reservoir; and (3) corrosion of production tubing. The model has been developed from production histories for Weber Sandstone reservoirs, Colorado and Wyoming, and has been applied to examples of reservoir production from Tensleep and Minnelusa reservoirs in Wyoming.

  15. DNA damage-induced centrosome amplification occurs via excessive formation of centriolar satellites.

    PubMed

    Löffler, H; Fechter, A; Liu, F Y; Poppelreuther, S; Krämer, A

    2013-06-13

    Centrosome amplification is a frequent phenomenon in malignancies and may facilitate tumorigenesis by promoting chromosomal instability. On the other hand, a centrosome inactivation checkpoint comprising centrosome amplification leading to elimination of cells by mitotic catastrophe has been described in response to DNA damage by ionizing radiation or cytostatic drugs. So far, the exact nature of DNA damage-induced centrosome amplification, which might be overduplication or fragmentation of existing centrosomes, has been controversial. To solve this controversy, we have established a method to distinguish between these two possibilities using A549 cells expressing photoconvertible CETN2-Dendra2. In response to various DNA-damaging treatments, centrosome amplification but not fragmentation was observed. Moreover, centrosome amplification was preceded by excessive formation of centrin-containing centriolar satellites, which were identified as de novo-generated atypical centrin dots staining positive for centriolar satellite markers but negative or only weakly positive for other established centrosomal markers, and which could be verified as centriolar satellites using immunogold electron microscopy. In line with this notion, disruption of dynein-mediated recruitment of centrosomal proteins via centriolar satellites suppressed centrosome amplification after DNA damage, and excessive formation of centriolar satellites could be inhibited by interference with Chk1, a known mediator of centrosome amplification in response to DNA damage. In conclusion, we provide a model in which a Chk1-mediated DNA damage checkpoint induces excessive formation of centriolar satellites constituting assembly platforms for centrosomal proteins, which subsequently leads to centrosome amplification.

  16. Death, Disease, and Dirty Power. Mortality and health damage due to air pollution from power plants

    SciTech Connect

    Schneider, Conrad G.

    2000-10-01

    The Clean Air Task Force, on behalf of the Clear the Air campaign, commissioned Abt Associates to quantify the health impacts of fine particle air pollution, commonly known as soot, from power plants, as well as the expected benefits (avoidable deaths, hospitalizations, etc.) of policies that would reduce fine particle pollution from power plants. The health effects analyzed include death, hospitalizations, emergency room visits, asthma attacks, and a variety of lesser respiratory symptoms. This report summarizes the findings of the Abt Associates study, reviews the contribution of power plants to fine particle pollution, and discusses policies that will reduce power plant fine particle pollution and thus save thousands of lives. Key findings include: Fine particle pollution from US power plants cuts short the lives of over 30,000 people each year. In more polluted areas, fine particle pollution can shave several years off its victims' lives. Hundreds of thousands of Americans suffer from asthma attacks, cardiac problems and upper and lower respiratory problems associated with fine particles from power plants. The elderly, children, and those with respiratory disease are most severely impacted by fine particle pollution from power plants. Metropolitan areas with large populations near coal-fired power plants feel their impacts most acutely - their attributable death rates are much higher than in areas with few or no coal-fired power plants. Power plants outstrip all other polluters as the largest source of sulfates - the major component of fine particle pollution - in the US Approximately two-thirds (over 18,000) of the deaths due to fine particle pollution from power plants could be avoided by implementing policies that cut power plant sulfur dioxide and nitrogen oxide pollution 75 percent below 1997 emission levels. Fine particle pollution is responsible for increased risk of death and shortened life spans. Abt Associates' findings are based on a body of well

  17. Formation of plasma induced surface damage in silica glass etching for optical waveguides

    NASA Astrophysics Data System (ADS)

    Choi, D. Y.; Lee, J. H.; Kim, D. S.; Jung, S. T.

    2004-06-01

    Ge, B, P-doped silica glass films are widely used as optical waveguides because of their low losses and inherent compatibility with silica optical fibers. These films were etched by ICP (inductively coupled plasma) with chrome etch masks, which were patterned by reactive ion etching (RIE) using chlorine-based gases. In some cases, the etched surfaces of silica glass were very rough (root-mean square roughness greater than 100 nm) and we call this phenomenon plasma induced surface damage (PISD). Rough surface cannot be used as a platform for hybrid integration because of difficulty in alignment and bonding of active devices. PISD reduces the etch rate of glass and it is very difficult to remove residues on a rough surface. The objective of this study is to elucidate the mechanism of PISD formation. To achieve this goal, PISD formation during different etching conditions of chrome etch mask and silica glass was investigated. In most cases, PISD sources are formed on a glass surface after chrome etching, and metal compounds are identified in theses sources. Water rinse after chrome etching reduces the PISD, due to the water solubility of metal chlorides. PISD is decreased or even disappeared at high power and/or low pressure in glass etching, even if PISD sources were present on the glass surface before etching. In conclusion, PISD sources come from the chrome etching process, and polymer deposition on these sources during the silica etching cause the PISD sources to grow. In the area close to the PISD source there is a higher ion flux, which causes an increase in the etch rate, and results in the formation of a pit.

  18. Laser induced damage in multilayer dielectric gratings due to ultrashort laser pulses. Revision 1

    SciTech Connect

    Shore, B.W.; Stuart, B.C.; Feit, M.D.; Rubenchik, A.M.; Perry, M.D.

    1995-07-11

    Chirped pulse amplification is increasingly used to produce intense ultrashort laser pulses. When high-efficiency gratings are the dispersive element, as in the LLNL Petawatt laser, their susceptibility to laser induced damage constitutes a limitation on the peak intensities that can be reached. To obtain robust gratings, it is necessary to understand the causes of short-pulse damage, and to recognize the range of design options for high efficiency gratings. Metal gratings owe their high efficiency to their high conductivity. To avoid the inevitable light absorption that accompanies conductivity, we have developed designs for high efficiency rejection gratings that use only transparent dielectric materials. These combine the reflectivity of a multi-layer dielectric stack with a diffraction grating. We report here our present understanding of short-pulse laser induced damage, as it applies to dielectric gratings.

  19. Laser induced damage in multilayer dielectric gratings due to ultrashort laser pulses

    SciTech Connect

    Shore, B.W.; Stuart, B.C.; Feit, M.D.; Rubenchik, A.M.; Perry, M.D.

    1995-05-26

    Chirped pulse amplification is increasingly used to produce intense ultrashort laser pulses. When high-efficiency gratings are the dispersive element, as in the LLNL Petawatt laser, their susceptibility to laser induced damage constitutes a limitation on the peak intensities that can be reached. To obtain robust gratings, it is necessary to understand the causes of short-pulse damage, and to recognize the range of design options for high efficiency gratings. Metal gratings owe their high efficiency to their high conductivity. To avoid the inevitable light absorption that accompanies conductivity, we have developed designs for high efficiency reflection gratings that use only transparent dielectric materials. These combine the reflectivity of a multilayer dielectric stack with a diffraction grating. We report here our present understanding of short-pulse laser induced damage, as it applies to dielectric gratings.

  20. Evaluation of Surface Damage of Organic Films due to Irradiation with Energetic Ion Beams

    SciTech Connect

    Hada, Masaki; Hontani, Yusaku; Ichiki, Kazuya; Seki, Toshio; Ibuki, Sachi; Ninomiya, Satoshi; Matsuo, Jiro; Aoki, Takaaki

    2011-01-07

    The surface of L-leucine films irradiated with an Ar{sub 5000} cluster ion beam (5 keV) was characterized by using the X-ray reflective (XRR) measurement method, atomic force microscopy (AFM) and ellipsometry. No significant damage was detected on the surface of the L-leucine films irradiated with the Ar cluster ion beam. Therefore, the large cluster-low-energy (about 1 eV/atom) beam would be suitable for low-damage etching of organic materials.

  1. Adverse effects of the antimalaria drug, mefloquine: due to primary liver damage with secondary thyroid involvement?

    PubMed Central

    Croft, Ashley M; Herxheimer, Andrew

    2002-01-01

    Background Mefloquine is a clinically important antimalaria drug, which is often not well tolerated. We critically reviewed 516 published case reports of mefloquine adverse effects, to clarify the phenomenology of the harms associated with mefloquine, and to make recommendations for safer prescribing. Presentation We postulate that many of the adverse effects of mefloquine are a post-hepatic syndrome caused by primary liver damage. In some users we believe that symptomatic thyroid disturbance occurs, either independently or as a secondary consequence of the hepatocellular injury. The mefloquine syndrome presents in a variety of ways including headache, gastrointestinal disturbances, nervousness, fatigue, disorders of sleep, mood, memory and concentration, and occasionally frank psychosis. Previous liver or thyroid disease, and concurrent insults to the liver (such as from alcohol, dehydration, an oral contraceptive pill, recreational drugs, and other liver-damaging drugs) may be related to the development of severe or prolonged adverse reactions to mefloquine. Implications We believe that people with active liver or thyroid disease should not take mefloquine, whereas those with fully resolved neuropsychiatric illness may do so safely. Mefloquine users should avoid alcohol, recreational drugs, hormonal contraception and co-medications known to cause liver damage or thyroid damage. With these caveats, we believe that mefloquine may be safely prescribed in pregnancy, and also to occupational groups who carry out safety-critical tasks. Testing Mefloquine's adverse effects need to be investigated through a multicentre cohort study, with small controlled studies testing specific elements of the hypothesis. PMID:11914150

  2. Speech and language therapy for dysarthria due to non-progressive brain damage.

    PubMed

    Sellars, C; Hughes, T; Langhorne, P

    2001-01-01

    Dysarthria is a common sequel of non-progressive brain damage (typically stroke and traumatic brain damage). Impairment-based therapy and a wide variety of compensatory management strategies are undertaken by speech and language therapists with this patient population. To determine the efficacy of speech and language therapy interventions for adults with dysarthria following non-progressive brain damage. This review has drawn on the search strategies developed for the following Cochrane Groups as a whole: Stroke, Injuries, and Infectious Diseases. Relevant trials were identified in the Specialised Registers of Controlled Trials (see Review Group Details for more information). We also searched the trials register of the Cochrane Rehabilitation and Related Therapies Field. The Cochrane Controlled Trials Register, MEDLINE, EMBASE, CINAHL, PsycLIT, and Linguistics and Language Behavior Abstracts were electronically searched. Hand-searching of The International Journal of Language and Communication Disorders and of reference lists from relevant articles and conference proceedings was also undertaken. Colleagues were approached to identify other possible published and unpublished studies. Date of most recent searches: May 2000. Unconfounded randomised controlled trials. One reviewer assessed trial quality. Two co-reviewers were available to examine any potential trials for possible inclusion in the review. No trials of the required standard were identified. There is no evidence of the quality required by this review to support or refute the effectiveness of Speech and Language Therapy interventions for dysarthria following non-progressive brain damage. There is an urgent need for good quality research in this area.

  3. Speech and language therapy for dysarthria due to nonprogressive brain damage: a systematic Cochrane review.

    PubMed

    Sellars, Cameron; Hughes, Thomas; Langhorne, Peter

    2002-02-01

    Dysarthria is a common sequel of nonprogressive brain damage (typically stroke and traumatic brain damage). Impairment-based therapy and a wide variety of compensatory management strategies are undertaken by speech and language therapists with this patient population. To determine the efficacy of speech and language therapy interventions for adults with dysarthria following nonprogressive brain damage. Systematic review. This review has drawn on the search strategies developed for the following Cochrane Groups as a whole: Stroke, Injuries, and Infectious Diseases. Relevant trials were identified in the Specialised Registers of Controlled Trials. We also searched the trials register of the Cochrane Rehabilitation and Related Therapies Field. The Cochrane Controlled Trials Register, MEDLINE, EMBASE, CINAHL, PsycLIT, and Linguistics and Language Behavior Abstracts were electronically searched. Hand-searching of the International Journal of Language and Communication Disorders and of reference lists from relevant articles and conference proceedings was also undertaken. Colleagues were approached to identify other possible published and unpublished studies. Unconfounded randomized controlled trials. One reviewer assessed trial quality. Two co-reviewers were available to examine any potential trials for possible inclusion in the review. No trials of the required standard were identified. There is no evidence of the quality required by this review to support or refute the effectiveness of speech and language therapy interventions for dysarthria following nonprogressive brain damage. There is an urgent need for good quality research in this area.

  4. DNA damage due to thermomechanical effects caused by heavy ions propagating in tissue

    NASA Astrophysics Data System (ADS)

    Surdutovich, Eugene; Yakubovich, Alexander V.; Solov'yov, Andrey V.

    2013-11-01

    We describe a multiscale approach to the physics of ion-beam cancer therapy, an approach suggested in order to understand the interplay of a large number of phenomena involved in radiation damage scenario occurring on a range of temporal, spatial, and energy scales. Then we focus the discussion on the shock waves on a nanoscale caused by ions propagating in tissue.

  5. Means of quantifying material loss due to corrosion damage using thermographic data

    NASA Astrophysics Data System (ADS)

    Rajic, Nikolas

    1998-03-01

    A method base don an inverse solution of the 1D heat conduction equation is applied to the general problem of estimating the local thickness of a structure form measurements of its thermal response to a flash excitation. Results are presented which demonstrate the efficacy of the method when applied to specimens with simulated corrosion damage.

  6. Characterization of damage due to stress corrosion cracking in carbon steel using nonlinear surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Zeitvogel, D. T.; Matlack, K. H.; Kim, J.-Y.; Jacobs, L. J.; Singh, P. M.; Qu, J.

    2013-01-01

    Cold rolled carbon steel 1018C is widely used in pressurized fuel pipelines. In these structures, stress corrosion cracking (SCC) can pose a significant problem because cracks initiate late in the lifetime and often unexpectedly, but grow fast once they get started. To ensure a safe operation it is crucial that any damage can be detected before the structural stability is reduced by large cracks. In the early stages of SCC, microstructural changes occur which in many cases increase the acoustic nonlinearity of the material. Therefore, an initially monochromatic Rayleigh wave is distorted and measurable higher harmonics are generated. Different levels of stress corrosion cracking is induced in five specimens. For each specimen, nonlinear ultrasonic measurements are performed before and after inducing the damage. For the measurements, oil coupled wedge transducers are used to generate and detect tone burst Rayleigh wave signals. The amplitudes of the received fundamental and second harmonic waves are measured at varying propagation distances to obtain a measure for the acoustic nonlinearity of the specimens. The results show a damage-dependent increase in nonlinearity for early stages of damage, indicating the feasibility of this nonlinear ultrasonic method to detect the initiation of stress corrosion cracking.

  7. Partial Interruption of Axonal Transport Due to Microtubule Breakage Accounts for the Formation of Periodic Varicosities after Traumatic Axonal Injury

    PubMed Central

    Tang-Schomer, Min D.; Johnson, Victoria E.; Baas, Peter W.; Stewart, William; Smith, Douglas H.

    2012-01-01

    Due to their viscoelastic nature, white matter axons are susceptible to damage by high strain rates produced during traumatic brain injury (TBI). Indeed, diffuse axonal injury (DAI) is one of the most common features of TBI, characterized by the hallmark pathological profiles of axonal bulbs at disconnected terminal ends of axons and periodic swellings along axons, known as “varicosities.” Although transport interruption underlies axonal bulb formation, it is unclear how varicosities arise, with multiple sites accumulating transported materials along one axon. Recently, axonal microtubules have been found to physically break during dynamic stretch-injury of cortical axons in vitro. Here, the same in vitro model was used in parallel with histopathological analyses of human brains acquired acutely following TBI to examine the potential role of mechanical microtubule damage in varicosity formation post-trauma. Transmission electron microscopy (TEM) following in vitro stretch-injury revealed periodic breaks of individual microtubules along axons that regionally corresponded with undulations in axon morphology. However, typically less than a third of microtubules were broken in any region of an axon. Within hours, these sites of microtubule breaks evolved into periodic swellings. This suggests axonal transport may be halted along one broken microtubule, yet can proceed through the same region via other intact microtubules. Similar axonal undulations and varicosities were observed following TBI in humans, suggesting primary microtubule failure may also be a feature of DAI. These data indicate a novel mechanism of mechanical microtubule damage leading to partial transport interruption and varicosity formation in traumatic axonal injury. PMID:22079153

  8. Modeling crater formation in femtosecond-pulse laser damage from basic principles.

    PubMed

    Mitchell, Robert A; Schumacher, Douglass W; Chowdhury, Enam A

    2015-05-15

    We present the first fundamental simulation method for the determination of crater morphology due to femtosecond-pulse laser damage. To this end we have adapted the particle-in-cell (PIC) method commonly used in plasma physics for use in the study of laser damage and developed the first implementation of a pair potential for PIC codes. We find that the PIC method is a complementary approach to modeling laser damage, bridging the gap between fully ab-initio molecular dynamics approaches and empirical models. We demonstrate our method by modeling a femtosecond-pulse laser incident on a flat copper slab for a range of intensities.

  9. Speech and language therapy for dysarthria due to non-progressive brain damage.

    PubMed

    Sellars, C; Hughes, T; Langhorne, P

    2002-01-01

    Dysarthria is a common sequel of non-progressive brain damage (typically stroke and traumatic brain damage). Impairment-based therapy and a wide variety of compensatory management strategies are undertaken by speech and language therapists with this patient population. To determine the efficacy of speech and language therapy interventions for adults with dysarthria following non-progressive brain damage. This review has drawn on the search strategies developed for the following Cochrane Groups as a whole: Stroke, Injuries, Movement Disorders and Infectious Diseases. Relevant trials were identified in the Specialised Registers of Controlled Trials (see Review Group details for more information). We also searched the trials register of the Cochrane Rehabilitation and Related Therapies Field. The Trials Registers were last searched in December 2001. The Cochrane Controlled Trials Register (Cochrane Library 2002, Issue 1), MEDLINE (1966-December 2001), EMBASE (1980-December 2001), CINAHL (1983-December 2001), PsycINFO (1974-February 2002) and Linguistics and Language Behavior Abstracts (1983-October 2001) were searched electronically. We handsearched the International Journal of Language and Communication Disorders (1966-2002, Issue 1) and selected conference proceedings, and scanned the reference lists of relevant articles. Colleagues were approached to identify other possible published and unpublished studies. Unconfounded randomised controlled trials. One reviewer assessed trial quality. Two co-reviewers were available to examine any potential trials for possible inclusion in the review. No trials of the required standard were identified. There is no evidence of the quality required by this review to support or refute the effectiveness of Speech and Language Therapy interventions for dysarthria following non-progressive brain damage. There is an urgent need for good quality research in this area.

  10. Speech and language therapy for dysarthria due to non-progressive brain damage.

    PubMed

    Sellars, C; Hughes, T; Langhorne, P

    2005-07-20

    Dysarthria is a common sequel of non-progressive brain damage (typically stroke and traumatic brain damage). Impairment-based therapy and a wide variety of compensatory management strategies are undertaken by speech and language therapists with this patient population. To determine the efficacy of speech and language therapy interventions for adults with dysarthria following non-progressive brain damage. We searched the trials registers of the following Cochrane Groups: Stroke, Injuries, Movement Disorders and Infectious Diseases. We also searched the trials register of the Cochrane Rehabilitation and Related Therapies Field. The trials registers were last searched in September 2004. The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 2, 2004), MEDLINE (1966 to September 2004), EMBASE (1980 to September 2004), CINAHL (1983 to September 2004), PsycINFO (1974 to October 2004), and Linguistics and Language Behavior Abstracts (1983 to December 2004) were searched electronically. We handsearched the International Journal of Language and Communication Disorders (1966 to 2005, Issue 1) and selected conference proceedings, and scanned the reference lists of relevant articles. We approached colleagues and speech and language therapy training institutions to identify other possible published and unpublished studies. Unconfounded randomised controlled trials (RCTs). One author assessed trial quality. Two co-authors were available to examine any potential trials for possible inclusion in the review. No trials of the required standard were identified. There is no evidence of the quality required by this review to support or refute the effectiveness of speech and language therapy interventions for dysarthria following non-progressive brain damage. Despite the recent commencement of a RCT of optimised speech and language therapy for communication difficulties after stroke, there continues to be an urgent need for good quality research in this

  11. Obesity-exposed oocytes accumulate and transmit damaged mitochondria due to an inability to activate mitophagy.

    PubMed

    Boudoures, Anna L; Saben, Jessica; Drury, Andrea; Scheaffer, Suzanne; Modi, Zeel; Zhang, Wendy; Moley, Kelle H

    2017-06-01

    Mitochondria are the most prominent organelle in the oocyte. Somatic cells maintain a healthy population of mitochondria by degrading damaged mitochondria via mitophagy, a specialized autophagy pathway. However, evidence from previous work investigating the more general macroautophagy pathway in oocytes suggests that mitophagy may not be active in the oocyte. This would leave the vast numbers of mitochondria - poised to be inherited by the offspring - vulnerable to damage. Here we test the hypothesis that inactive mitophagy in the oocyte underlies maternal transmission of dysfunctional mitochondria. To determine whether oocytes can complete mitophagy, we used either CCCP or AntimycinA to depolarize mitochondria and trigger mitophagy. After depolarization, we did not detect co-localization of mitochondria with autophagosomes and mitochondrial DNA copy number remained unchanged, indicating the non-functional mitochondrial population was not removed. To investigate the impact of an absence of mitophagy in oocytes with damaged mitochondria on offspring mitochondrial function, we utilized in vitro fertilization of high fat high sugar (HF/HS)-exposed oocytes, which have lower mitochondrial membrane potential and damaged mitochondria. Here, we demonstrate that blastocysts generated from HF/HS oocytes have decreased mitochondrial membrane potential, lower metabolites involved in ATP generation, and accumulation of PINK1, a mitophagy marker protein. This mitochondrial phenotype in the blastocyst mirrors the phenotype we show in HF/HS exposed oocytes. Taken together, these data suggest that the mechanisms governing oocyte mitophagy are fundamentally distinct from those governing somatic cell mitophagy and that the absence of mitophagy in the setting of HF/HS exposure contributes to the oocyte-to-blastocyst transmission of dysfunctional mitochondria. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  12. Damages in American Samoa due to the 29 September 2009 Samoa Islands Region Earthquake Tsunami

    NASA Astrophysics Data System (ADS)

    Okumura, Y.; Takahashi, T.; Suzuki, S.

    2009-12-01

    A large earthquake of Mw 8.0 occurred in Samoa Islands Region in the early morning on 29 September 2009 (local time). A Large Tsunami generated by the earthquake hit Samoa, American Samoa, Tonga. Total 192 people were died or missing in these three countries (22 October 2009). The authors surveyed in Tutuila Island, American Samoa from 6 to 8 in October 2009 with the aim to find out damages in the disaster. In American Samoa, death and missing toll was 35. The main findings are as follows; first, human damages were little for tsunami run-up height of about 4 to 6 meters and tsunami arrival time of about 20 minutes. We can suppose that residents evacuated quickly after feeling shaking or something. Secondly, houses were severely damaged in some low elevation coastal villages such as Amanave, Leone, Pago Pago, Tula and so on. Third, a power plant and an airport, which are important infrastructures in relief and recovery phase, were also severely damaged. Inundation depth at the power plant was 2.31 meters. A blackout in the daytime lasted when we surveyed. On the other hand, the airport could use already at that time. But it was closed on the first day in the disaster because of a lot of disaster debris on the runway carried by tsunami. Inundation depth at the airport fence was measured in 0.7 to 0.8 meters. Other countries in the south-western Pacific region may have power plants or airports with similar risk, so it should be assessed against future tsunami disasters. Inundated thermal power plant in Pago Pago Debris on runway in Tafuna Airport (Provided by Mr. Chris Soti, DPA)

  13. Analysis of progressive damage in thin circular laminates due to static-equivalent impact loads

    NASA Technical Reports Server (NTRS)

    Shivakumar, K. N.; Elber, W.; Illg, W.

    1983-01-01

    Clamped circular graphite/epoxy plates (25.4, 38.1, and 50.8 mm radii) with an 8-ply quasi-isotropic layup were analyzed for static-equivalent impact loads using the minimum-total-potential-energy method and the von Karman strain-displacement equations. A step-by-step incremental transverse displacement procedure was used to calculate plate load and ply stresses. The ply failure region was calculated using the Tsai-Wu criterion. The corresponding failure modes (splitting and fiber failure) were determined using the maximum stress criteria. The first-failure mode was splitting and initiated first in the bottom ply. The splitting-failure thresholds were relatively low and tended to be lower for larger plates than for small plates. The splitting-damage region in each ply was elongated in its fiber direction; the bottom ply had the largest damage region. The calculated damage region for the 25.4-mm-radius plate agreed with limited static test results from the literature.

  14. Severe esophageal damage due to button battery ingestion: can it be prevented?

    PubMed

    Yardeni, D; Yardeni, H; Coran, A G; Golladay, E S

    2004-07-01

    Batteries represent less than 2% of foreign bodies ingested by children, but in the last 2 decades, the frequency has continuously increased. Most ingestions have an uneventful course, but those that lodge in the esophagus can lead to serious complications and even death. Medline was used to search the English medical literature, combining "button battery" and "esophageal burn" as keywords. Cases were studied for type, size, and source of the batteries; duration and location of the battery impaction in the esophagus; symptoms; damage caused by the battery; and outcome. Nineteen cases of esophageal damage have been reported since 1979. Batteries less than 15 mm in diameter almost never lodged in the esophagus. Only 3% of button batteries were larger than 20 mm but were responsible for the severe esophageal injuries in this series. These data suggest that manufacturers should replace large batteries with smaller ones and thus eliminate most of the complications. When the battery remains in the esophagus, endoscopic examination and removal done urgently will allow assessment of the esophageal damage, and treatment can be tailored accordingly. There is a need for more public education about the dangers of battery ingestion; this information should be included as part of the routine guidelines for childproofing the home.

  15. Constitutive Modeling for Particle-Dispersed Composites with Degradation Due to Interfacial Damage

    SciTech Connect

    Chang, Huajian

    2002-07-01

    The composite materials are susceptible to interfacial delamination. The overall properties of composites will degrade dramatically if the interface between the particles and the matrix material undertakes interfacial damage. In present paper, the effects of interfacial delamination on the macro properties of composites are evaluated by the Equivalent Inclusion Method (EIM) with some modifications and supplementation on the conventional one, which was originally proposed by Eshelby. The meso-local behaviors of particle, matrix, as well as their interface are theoretically modeled, and the relationships between these behaviors and the macro stress/stress field are established. Upon modeling the damaged interface with spring layers and making equivalent of stress and strain inside a real particle to those inside the corresponding virtual inclusion, a modified Eshelby tensor and the damage-relevant tensor of the inclusions are derived explicitly. These tensors can be conveniently incorporated into the constitutive model, and make it available to assess the effects of delamination. Some numerical calculations are carried out to verify the performance of the present model. (author)

  16. Pre-treatment with glutamine reduces genetic damage due to cancer treatment with cisplatin.

    PubMed

    Oliveira, R J; Sassaki, E S; Monreal, A C D; Monreal, M T F D; Pesarini, J R; Mauro, M O; Matuo, R; Silva, A F; Zobiole, N N; Siqueira, J M; Ribeiro, L R; Mantovani, M S

    2013-12-02

    Cisplatin is an effective antineoplastic drug. However, it provokes considerable collateral effects, including genotoxic and clastogenic activity. It has been reported that a diet rich in glutamine can help inhibit such collateral effects. We evaluated this activity in 40 Swiss mice, distributed into eight experimental groups: G1 - Control group (PBS 0.1 mL/10 g body weight); G2 - cisplatin group (cisplatin 6 mg/kg intraperitoneally); G3, G4, G5 - glutamine groups (glutamine at 150, 300, and 600 mg/kg, respectively; orally); G6, G7, G8 - Pre-treatment groups (glutamine at 150, 300, and 600 mg/kg, respectively; orally and cisplatin 6 mg/kg intraperitonially). For the micronucleus assay, samples of blood were collected (before the first use of the drugs at T0, then 24 (T1) and 48 (T2) hours after the first administration). For the comet assay, blood samples were collected only at T2. The damage reduction percentages for the micronucleus assay were 90.0, 47.3, and 37.3% at T1 and 46.0, 38.6, and 34.7% at T2, for G6, G7, and G8 groups, respectively. For the comet assay, the damage reduction percentages were 113.0, 117.4, and 115.0% for G6, G7, and G8, respectively. We conclude that glutamine is able to prevent genotoxic and clastogenic damages caused by cisplatin.

  17. Computational Hydrocode Study of Target Damage due to Fragment-Blast Impact

    SciTech Connect

    Hatch-Aguilar, T; Najjar, F; Szymanski, E

    2011-03-24

    A target's terminal ballistic effects involving explosively generated fragments, along with the original blast, are of critical importance for many different security and safety related applications. Personnel safety and protective building design are but a few of the practical disciplines that can gain from improved understanding combined loading effects. Traditionally, any engineering level analysis or design effort involving explosions would divide the target damage analysis into two correspondingly critical areas: blast wave and fragment related impact effects. The hypothesis of this paper lies in the supposition that a linear combination of a blast-fragment loading, coupled with an accurate target response description, can lead to a non-linear target damage effect. This non-linear target response could then stand as the basis of defining what a synergistic or combined frag-blast loading might actually look like. The table below, taken from Walters, et. al. categorizes some of the critical parameters driving any combined target damage effect and drives the evaluation of results. Based on table 1 it becomes clear that any combined frag-blast analysis would need to account for the target response matching similar ranges for the mechanics described above. Of interest are the critical times upon which a blast event or fragment impact loading occurs relative to the target's modal response. A blast, for the purposes of this paper is defined as the sudden release of chemical energy from a given material (henceforth referred to as an energetic material) onto its surrounding medium. During the coupling mechanism a discrete or discontinuous shockwave is generated. This shockwave travels outward from the source transferring energy and momentum to any surrounding objects including personnel and engineering structures. From an engineering perspective blast effects are typically characterized by way of physical characteristics such as Peak Pressure (PP), Time of Arrival (TOA

  18. A damage mechanics approach for quantifying stress changes due to brittle failure of porous rocks

    NASA Astrophysics Data System (ADS)

    Jacquey, Antoine B.; Cacace, Mauro; Blöcher, Guido; Milsch, Harald; Scheck-Wenderoth, Magdalena

    2016-04-01

    Natural fault zones or man-made injection or production of fluid impact the regional stress distribution in Earth's crust and can be responsible for localized stress discontinuities. Understanding the processes controlling fracturing of the porous rocks and mechanical behaviour of fault zones is therefore of interest for several applications including geothermal energy production. In this contribution, we will present a thermodynamically consistent visco-poroelastic damage model which can deal with the multi-scale and multi-physics nature of the physical processes controlling the deformation of porous rocks during and after brittle failure. Deformation of a porous medium is crucially influenced by the changes in the effective stress. Considering a strain-formulated yield cap and the compaction-dilation transition, three different regimes can be identified: quasi-elastic deformation, cataclastic compaction with microcracking (damage accumulation) and macroscopic brittle failure with dilation. The governing equations for deformation, damage accumulation/healing and fluid flow have been implemented in a fully-coupled finite-element-method based framework (MOOSE). The MOOSE framework provides a powerful and flexible platform to solve multiphysics problems implicitly and in a tightly coupled manner on unstructured meshes which is of interest for such non-linear context. To illustrate the model, simulation of a compaction experiment of a sandstone leading to shear failure will be presented which allows to quantify the stress drop accompanying the failure. Finally, we will demonstrate that this approach can also be used at the field scale to simulate hydraulic fracturing and assess the resulting changes in the stress field.

  19. Damage initiation, progression and failure of polymer matrix composites due to manufacturing induced defects

    NASA Astrophysics Data System (ADS)

    Chowdhury, Khairul Alam

    In polymer matrix composites (PMCs) manufacturing processes can induce defects, e.g., voids, fiber misalignment, irregular fiber distribution in the cross-section and broken fibers. The effects of such defects can be beneficial or deleterious depending on whether they cause failure suppression or enhancement by localized deformation processes e.g., crazing, shear yielding and fiber-matrix debonding. In this study, a computational approach is formulated and implemented to develop solutions for general boundary-value problems for PMC microstructures that accounts for micromechanics-based constitutive relations including fine scale mechanisms of material failure. The defects considered are voids, and the microstructure is explicitly represented by a distribution of fibers and voids embedded in a polymer matrix. Fiber is modeled as a linearly elastic material while the polymer matrix is modeled as an elastic-viscoplastic material. Two distinct models for the matrix behavior are implemented: (i) Drucker-Prager type Bodner model that accounts for rate and pressure-sensitivity, and (ii) improved macromolecular constitutive model that also accounts for temperature dependence, small-strain softening and large-strain hardening. Damage is simulated by the Gearing-Anand craze model as a reference model and by a new micromechanical craze model, developed to account for craze initiation, growth and breakdown. Critical dilatational energy density criterion is utilized to predict fiber-matrix debonding through cavitation induced matrix cracking. An extensive parametric study is conducted in which the roles of void shape, size and distribution relative to fiber in determining damage initiation and evolution are investigated under imposed temperature and strain rate conditions. Results show there are significant effects of voids on microstructural damage as well as on the overall deformational and failure response of composites.

  20. Gonadal damage due to radioactive iodine (I131) treatment for thyroid carcinoma.

    PubMed Central

    Ahmed, S. R.; Shalet, S. M.

    1985-01-01

    Papillary carcinoma of the thyroid is the most common type of thyroid cancer and is associated with a good prognosis. Complications of treatment with surgery and radioiodine are uncommon. We report the case of a 13 year old boy who developed testicular damage following treatment with radioactive iodine 350 mCi for a papillary carcinoma of the thyroid. Four years after radioiodine treatment there has been no suggestion of recovery of spermatogenesis. Detailed follow-up studies of similarly treated young patients are required to define the incidence of this complication and to determine its reversibility. PMID:4022871

  1. Skeletal muscle damage and impaired regeneration due to LPL-mediated lipotoxicity

    PubMed Central

    Tamilarasan, K P; Temmel, H; Das, S K; Al Zoughbi, W; Schauer, S; Vesely, P W; Hoefler, G

    2012-01-01

    According to the concept of lipotoxicity, ectopic accumulation of lipids in non-adipose tissue induces pathological changes. The most prominent effects are seen in fatty liver disease, lipid cardiomyopathy, non-insulin-dependent diabetes mellitus, insulin resistance and skeletal muscle myopathy. We used the MCK(m)-hLPL mouse distinguished by skeletal and cardiac muscle-specific human lipoprotein lipase (hLPL) overexpression to investigate effects of lipid overload in skeletal muscle. We were intrigued to find that ectopic lipid accumulation induced proteasomal activity, apoptosis and skeletal muscle damage. In line with these findings we observed reduced Musculus gastrocnemius and Musculus quadriceps mass in transgenic animals, accompanied by severely impaired physical endurance. We suggest that muscle loss was aggravated by impaired muscle regeneration as evidenced by reduced cross-sectional area of regenerating myofibers after cardiotoxin-induced injury in MCK(m)-hLPL mice. Similarly, an almost complete loss of myogenic potential was observed in C2C12 murine myoblasts upon overexpression of LPL. Our findings directly link lipid overload to muscle damage, impaired regeneration and loss of performance. These findings support the concept of lipotoxicity and are a further step to explain pathological effects seen in muscle of obese patients, patients with the metabolic syndrome and patients with cancer-associated cachexia. PMID:22825472

  2. Variation of the enhanced biologically damaging solar UV due to clouds.

    PubMed

    Parisi, Alfio V; Downs, Nathan

    2004-07-01

    The variation of the biologically damaging solar UV (UVBE) enhanced by clouds above that of clear sky UVBE has been investigated. This was undertaken for summer through to winter for SZA of 5 to 60 degrees employing an integrated automatic cloud and spectral UV measurement system that recorded the solar UV spectra and the sky images at five minute intervals. The UVBE calculated with action spectra with higher relative effectiveness in the UVA produced the lower percentage of cloud enhanced cases. The DNA UVBE provided the highest percentage of cloud enhanced cases compared to the total number of UV scans with 2.2% cloud enhanced cases. As a comparison, the plant and fish melanoma UVBE provided the lowest percentage of cloud enhanced cases with 0.6 to 0.8% cloud enhanced cases. For the cases of cloud enhanced UVBE, the average ratio of the measured UVBE to calculated cloud free UVBE for the photokeratitis, cataracts, plant, generalized plant damage and fish melanoma action spectra was 1.21 to 1.25. In comparison, the highest value of 1.4 was for the DNA action spectrum.

  3. A systematic approach for the prevention and treatment of formation damage caused by asphaltene deposition

    SciTech Connect

    Leontaritis, K.J.; Amaefule, J.O.; Charles, R.E. )

    1994-08-01

    Asphaltene plugging is a known cause of near-wellbore formation damage. Deposited asphaltenes can reduce effective hydrocarbon mobility by (1) blocking the pore throats; (2) adsorbing onto the rock, thereby altering the formation wettability from water-wet to oil-wet; and (3) increasing hydrocarbon viscosity by nucleating water-in-oil emulsions. Asphaltene flocculation and deposition can be avoided in some, but not all, cases. Some formation damage resulting from asphaltene plugging is permanent and hence must be prevented rather than treated. Prevention of asphaltene-induced formation damage should be started in the early stages of drilling and well completion, once the oil is known to be asphaltenic. This paper presents a systematic approach to successful diagnosis, prevention, and mitigation of asphaltene problems during recovery of asphaltenic oils. A mechanism of asphaltene flocculation and deposition is proposed and analyzed, and the previously defined concept of asphaltene deposition envelope is further refined. Diagnostic technology is presented that can test the compatibility of drilling and completion fluids with any asphaltenic oil. Important issues that need to be considered in the design of treatments for asphaltene removal are discussed. Finally, the paper presents a methodology for restoring unfavorable wettability changes caused by asphaltene deposition.

  4. Signaling molecules regulating phenotypic conversions of astrocytes and glial scar formation in damaged nerve tissues.

    PubMed

    Koyama, Yutaka

    2014-12-01

    Phenotypic conversion of astrocytes from resting to reactive (i.e., astrocytic activation) occurs in numerous brain disorders. Astrocytic activation in severely damaged brain regions often leads to glial scar formation. Because astrocytic activation and glial scar largely affect the vulnerability and tissue repair of damaged brain, numerous studies have been made to clarify mechanisms regulating the astrocytic phenotype. The phenotypic conversion is accompanied by the increased expression of intermediate filament proteins and the induction of hypertrophy in reactive astrocytes. Severe brain damage results in proliferation and migration of reactive astrocytes, which lead to glial scar formations at the injured areas. Gliogenesis from neural progenitors in the adult brain is also involved in astrocytic activation and glial scar formation. Recent studies have shown that increased expression of connexin 43, aquaporin 4, matrix metalloproteinase 9, and integrins alter the function of astrocytes. The transcription factors: STAT3, OLIG2, SMAD, NF-κB, and Sp1 have been suggested to play regulatory roles in astrocytic activation and glial scar formation. In this review, I discuss the roles of these key molecules regulating the pathophysiological functions of reactive astrocytes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Inflammatory damage on respiratory and nervous systems due to hRSV infection.

    PubMed

    Bohmwald, Karen; Espinoza, Janyra A; Becerra, Daniela; Rivera, Katherine; Lay, Margarita K; Bueno, Susan M; Riedel, Claudia A; Kalergis, Alexis M

    2015-10-01

    The exacerbated inflammatory response elicited by human Respiratory Syncytial Virus (hRSV) in the lungs of infected patients causes a major health burden in the pediatric and elderly population. Since the discovery of hRSV, the exacerbated host immune-inflammatory response triggered by this virus has been extensively studied. In this article, we review the effects on the airways caused by immune cells and cytokines/chemokines secreted during hRSV infection. While molecules such as interferons contribute at controlling viral infection, IL-17 and others produce damage to the hRSV-infected lung. In addition to affecting the airways, hRSV infection can cause significant neurologic abnormalities in the host, such as seizures and encephalopathy. Although the origin of these symptoms remains unclear, studies from patients suffering neurological alteration suggest an involvement of the inflammatory response against hRSV.

  6. [Damage to implants due to high-frequency electrocautery : analysis of four fractured hip endoprostheses shafts].

    PubMed

    Konrads, C; Wente, M N; Plitz, W; Rudert, M; Hoberg, M

    2014-12-01

    In revision surgery of joints, high-frequency electrocauterization instruments are used for homeostasis and dissection of soft tissue. If there is contact of these instruments with the metal implants, flashover can occur. This can lead to thermal microstructural changes in the material and as a consequence may reduce the fatigue strength of the implant. Four cases of hip revision surgeries were analysed. In all cases flashovers occurred and secondarily, the titanium hip endoprosthesis stem broke in the neck section of the prosthesis. The conducted investigations showed that contact between the high-frequency instrument and the anterolateral aspect of the endoprosthesis neck had occurred. Electrothermal implant damage was found in the broken area. If in hip revision surgery the stem is not to be replaced, contact between high-frequency instruments and the metal implant should be avoided.

  7. Patterns of venous reflux and obstruction in patients with skin damage due to chronic venous disease.

    PubMed

    Labropoulos, Nicos; Patel, Parag J; Tiongson, Jay E; Pryor, Landon; Leon, Luis R; Tassiopoulos, Apostolos K

    2007-01-01

    Identified were characteristics of individuals with skin damage related to chronic venous disease. Patients with chronic venous disease (n = 164) were evaluated with duplex ultrasound imaging and were placed in classes 4, 5, and 6 according to the CEAP classification. Their findings were compared with 100 class 2 controls. The prevalence of deep venous thrombosis was higher in the study group (23.7%) versus controls (5.1%; P < .0001), as was the prevalence of deep, perforator, and combined patterns of disease (P < .0001, P < .0007, and P < .0001). The mean duration of disease in controls 2 was shorter compared with the study group (P = .0019). The prevalence of reflux and obstruction within the study group was higher than in controls (P = .0021). Skin changes accurately reflect severity of chronic venous disease. Superficial and perforator vein reflux is the major cause of disease.

  8. Stress and Damage in Polymer Matrix Composite Materials Due to Material Degradation at High Temperatures

    NASA Technical Reports Server (NTRS)

    McManus, Hugh L.; Chamis, Christos C.

    1996-01-01

    This report describes analytical methods for calculating stresses and damage caused by degradation of the matrix constituent in polymer matrix composite materials. Laminate geometry, material properties, and matrix degradation states are specified as functions of position and time. Matrix shrinkage and property changes are modeled as functions of the degradation states. The model is incorporated into an existing composite mechanics computer code. Stresses, strains, and deformations at the laminate, ply, and micro levels are calculated, and from these calculations it is determined if there is failure of any kind. The rationale for the model (based on published experimental work) is presented, its integration into the laminate analysis code is outlined, and example results are given, with comparisons to existing material and structural data. The mechanisms behind the changes in properties and in surface cracking during long-term aging of polyimide matrix composites are clarified. High-temperature-material test methods are also evaluated.

  9. Melatonin reduces mortality and oxidatively mediated hepatic and renal damage due to diquat treatment.

    PubMed

    Xu, Jingming; Sun, Shichun; Wei, Wei; Fu, Jianmin; Qi, Wenbo; Manchester, Lucien C; Tan, Dun-Xian; Reiter, Russel J

    2007-03-01

    The bipyridyl herbicide, diquat, is a potent prooxidant that generates superoxide anions through redox cycling in vivo. Exposure to elevated levels of this compound causes acute hepatic and renal toxicity as well as death in rodents. In the present study, we investigated whether melatonin, a free radical scavenger and antioxidant, could protect against diquat-induced hepatic and renal damage and whether the indole would improve survival of Kunming mice given a lethal dose of diquat. When mice were intraperitoneally (i.p.) given a single dose of diquat (50 mg/kg body weight), liver and kidney injuries were observed at 6 hr as indicated by elevated serum levels of both alanine aminotransferase (ALT) activity and blood urea nitrogen (BUN). In addition, lipid peroxidation levels in both liver and kidney showed significant increases as shown by elevated concentrations of F(2)-isoprostanes. The administration of melatonin (20 mg/kg) 30 min before the diquat injection resulted in a significant reduction in serum levels of ALT and BUN as well as hepatic and renal F(2)-isoprostanes levels. For the survival study, 75 mg/kg diquat was administered i.p. into mice to induce acute death. Without melatonin treatment, 10 of 23 (43.5%) mice died within 24 hr after diquat injection. Pretreatment with melatonin (20 mg/kg) 30 min prior to the injection of diquat and thereafter at 4-hr intervals until the end of the observation period (24 hr), reduced the death rate to two of 22 (9.1%) mice. Chi-squared test revealed a significant difference with P < or = 0.05. In conclusion, melatonin, a broad spectrum antioxidant, reduces hepatic and renal damage and lowers the death rate in diquat-treated mice.

  10. Formate can differentiate between hyperhomocysteinemia due to impaired remethylation and impaired transsulfuration

    PubMed Central

    Lamarre, Simon G.; Molloy, Anne M.; Reinke, Stacey N.; Sykes, Brian D.; Brosnan, Margaret E.

    2012-01-01

    Formate can differentiate between hyperhomocysteinemia due to impaired remethylation and impaired transsulfuration. Am J Physiol Endocrinol Metab 301: E000–E000, 2011. First published September 20, 2011; 10.1152/ajpendo.00345.2011.—We carried out a 1H-NMR metabolomic analysis of sera from vitamin B12-deficient rats. In addition to the expected increases in methylmalonate and homocysteine (Hcy), we observed an approximately sevenfold increase in formate levels, from 64 μM in control rats to 402 μM in vitamin B12-deficient rats. Urinary formate was also elevated. This elevation of formate could be attributed to impaired one-carbon metabolism since formate is assimilated into the one-carbon pool by incorporation into 10-formyl-THF via the enzyme 10-formyl-THF synthase. Both plasma and urinary formate were also increased in folate-deficient rats. Hcy was elevated in both the vitamin B12- and folate-deficient rats. Although plasma Hcy was also elevated, plasma formate was unaffected in vitamin B6-deficient rats (impaired transsulfuration pathway). These results were in accord with a mathematical model of folate metabolism, which predicted that reduction in methionine synthase activity would cause increased formate levels, whereas reduced cystathionine β-synthase activity would not. Our data indicate that formate provides a novel window into cellular folate metabolism, that elevated formate can be a useful indicator of deranged one-carbon metabolism and can be used to discriminate between the hyperhomocysteinemia caused by defects in the remethylation and transsulfuration pathways. PMID:21934042

  11. NEK8 regulates DNA damage-induced RAD51 foci formation and replication fork protection

    PubMed Central

    Abeyta, Antonio; Castella, Maria; Jacquemont, Celine; Taniguchi, Toshiyasu

    2017-01-01

    ABSTRACT Proteins essential for homologous recombination play a pivotal role in the repair of DNA double strand breaks, DNA inter-strand crosslinks and replication fork stability. Defects in homologous recombination also play a critical role in the development of cancer and the sensitivity of these cancers to chemotherapy. RAD51, an essential factor for homologous recombination and replication fork protection, accumulates and forms immunocytochemically detectable nuclear foci at sites of DNA damage. To identify kinases that may regulate RAD51 localization to sites of DNA damage, we performed a human kinome siRNA library screen, using DNA damage-induced RAD51 foci formation as readout. We found that NEK8, a NIMA family kinase member, is required for efficient DNA damage-induced RAD51 foci formation. Interestingly, knockout of Nek8 in murine embryonic fibroblasts led to cellular sensitivity to the replication inhibitor, hydroxyurea, and inhibition of the ATR kinase. Furthermore, NEK8 was required for proper replication fork protection following replication stall with hydroxyurea. Loading of RAD51 to chromatin was decreased in NEK8-depleted cells and Nek8-knockout cells. Single-molecule DNA fiber analyses revealed that nascent DNA tracts were degraded in the absence of NEK8 following treatment with hydroxyurea. Consistent with this, Nek8-knockout cells showed increased chromosome breaks following treatment with hydroxyurea. Thus, NEK8 plays a critical role in replication fork stability through its regulation of the DNA repair and replication fork protection protein RAD51. PMID:27892797

  12. Modeling dose deposition and DNA damage due to low-energy β(-) emitters.

    PubMed

    Alloni, D; Cutaia, C; Mariotti, L; Friedland, W; Ottolenghi, A

    2014-09-01

    One of the main issues of low-energy internal emitters concerns the very short ranges of the beta particles, versus the dimensions of the biological targets. Depending on the chemical form, the radionuclide may be more concentrated either in the cytoplasm or in the nucleus of the target cell. Consequently, since in most cases conventional dosimetry neglects this issue it may overestimate or underestimate the dose to the nucleus and hence the biological effects. To assess the magnitude of these deviations and to provide a realistic evaluation of the localized energy deposition by low-energy internal emitters, the biophysical track-structure code PARTRAC was used to calculate nuclear doses, DNA damage yields and fragmentation patterns for different localizations of radionuclides in human interphase fibroblasts. The nuclides considered in the simulations were tritium and nickel-63, which emit electrons with average energies of 5.7 (range in water of 0.42 μm) and 17 keV (range of 5 μm), respectively, covering both very short and medium ranges of beta-decay products. The simulation results showed that the largest deviations from the conventional dosimetry occur for inhomogeneously distributed short-range emitters. For uniformly distributed radionuclides selectively in the cytoplasm but excluded from the cell nucleus, the dose in the nucleus is 15% of the average dose in the cell in the case of tritium but 64% for nickel-63. Also, the numbers of double-strand breaks (DSBs) and the distributions of DNA fragments depend on subcellular localization of the radionuclides. In the low- and medium-dose regions investigated here, DSB numbers are proportional to the nuclear dose, with about 50 DSB/Gy for both studied nuclides. In addition, DSB numbers on specific chromosomes depend on the radionuclide localization in the cell as well, with chromosomes located more peripherally in the cell nucleus being more damaged by short-ranged emitters in cytoplasm compared with chromosomes

  13. Ovarian damage due to cyst removal: a comparison of endometriomas and dermoid cysts.

    PubMed

    Perlman, Signe; Kjer, Jens J

    2016-03-01

    Surgical treatment of endometriomas and potential damage to the ovary have been debated. Studies have described the inconsistent risk of unintended removal of ovarian tissue when a cystectomy of an endometrioma is performed. We evaluated the risk of inadvertently removed ovarian tissue during surgery by comparing specimens of endometriomas and dermoid cysts removed laparoscopically. The material included 326 women in a retrospective cohort study at Rigshospitalet, University hospital in Copenhagen, Denmark from 2011 to 2013. Surgery was performed laparoscopically for 393 benign cysts with a diagnosis of either endometrioma (n = 294) or dermoid cyst (n = 99). The microscopic existence of ovarian tissue in the cystectomy specimens were compared and correlation between CA 125 and size of cysts was examined. In total, 80.3% endometrioma cystectomies disclosed ovarian stroma compared with 17.2% of the resected dermoid cysts (p < 0.001). The difference was found despite skilled laparoscopic surgeons performing the procedure in the endometriosis cohort. A significant positive correlation between the size of endometriomas and the value of CA 125 was found (p < 0.009). The risk of removal of ovarian tissue during laparoscopic surgery is significantly higher for endometriomas than for dermoid cysts. © 2016 Nordic Federation of Societies of Obstetrics and Gynecology.

  14. [Interferon-alpha and liver fibrosis in patients with chronic damage due to hepatitis C virus].

    PubMed

    Gonzalez-Huezo, María Sarai; Gallegos-Orozco, Juan Fernando

    2003-01-01

    The present review focuses on the published information published regarding the effects of interferon alpha therapy on liver fibrosis in patients with chronic liver damage secondary to hepatitis C infection. Data reviewed included results of the in vitro effects of interferon on hepatic cell line cultures with regards to indirect markers of fibrosis, activation of hepatic stellate cells and oxidative stress response. In the clinical arena, there is current clear evidence of a favorable histological outcome in patients with sustained viral response to interferon therapy. For this reason, the current review focuses more on the histological outcomes regarding liver fibrosis in patients who have not attained viral response to therapy (non-responders) or who already have biopsy defined cirrhosis. Data in these patients were analyzed according to the results of objective testing of fibrosis through the assessment of liver biopsy and its change during time, specially because the morbidity and mortality of this disease is directly related to the complications of liver cirrhosis and not necessarily to the persistence of the hepatitis C virus. Lastly, it is concluded that the process of liver fibrosis/cirrhosis is a dynamic one and that there is some evidence to support the usefulness of interferon alpha therapy as a means to halt or retard the progression of hepatic fibrosis. The result of current clinical trials in which interferon therapy is being used to modify the progression of fibrosis in non-responders or cirrhotic patients is eagerly awaited.

  15. Damage in graphene due to electronic excitation induced by highly charged ions

    NASA Astrophysics Data System (ADS)

    Hopster, J.; Kozubek, R.; Ban-d'Etat, B.; Guillous, S.; Lebius, H.; Schleberger, M.

    2014-06-01

    Graphene is expected to be rather insensitive to ion irradiation. We demonstrate that single layers of exfoliated graphene sustain significant damage from irradiation with slow highly charged ions. We have investigated the ion induced changes of graphene after irradiation with highly charged ions of different charge states (q = 28-42) and kinetic energies ({{E}_{\\text{kin}}} = 150-450 keV). Atomic force microscopy images reveal that the ion induced defects are not topographic in nature but are related to a significant change in friction. To create these defects, a minimum charge state is needed. In addition to this threshold behaviour, the required minimum charge state as well as the defect diameter show a strong dependency on the kinetic energy of the projectiles. From the linear dependency of the defect diameter on the projectile velocity we infer that electronic excitations triggered by the incoming ion in the above-surface phase play a dominant role for this unexpected defect creation in graphene.

  16. Recent Advances in Targeted, Self-Assembling Nanoparticles to Address Vascular Damage Due to Atherosclerosis

    PubMed Central

    Chung, Eun Ji; Tirrell, Matthew

    2016-01-01

    Self-assembling nanoparticles functionalized with targeting moieties have significant potential for atherosclerosis nanomedicine. While self-assembly allows for easy construction (and degradation) of nanoparticles with therapeutic or diagnostic functionality, or both, the targeting agent can direct them to a specific molecular marker within a given stage of the disease. Therefore, supramolecular nanoparticles have been investigated in the last decade as molecular imaging agents or explored as nanocarriers that can decrease the systemic toxicity of drugs by producing accumulation predominantly in specific tissues of interest. In this review, we first describe the pathogenesis of atherosclerosis and the damage caused to vascular tissue, as well as the current diagnostic and treatment options. Then we provide an overview of targeted strategies using self-assembling nanoparticles and include liposomes, high density lipoproteins, protein cages, micelles, proticles, and perfluorocarbon nanoparticles. Finally, we elaborate on and provide an overview of current challenges, limitations, and future applications for personalized medicine in the context of atherosclerosis of self-assembling nanoparticles. PMID:26085109

  17. Electrothermic damage to the nail due to arcing in high-voltage discharge.

    PubMed

    Bielefeld, Lena; Mierdel, Katrin; Pollak, Stefan; Perdekamp, Markus Große

    2013-12-10

    The burn effects in high-voltage electrocutions are manifold ranging from inconspicuous marks to deep charring. Apart from lesions caused by direct contact with a live conductor, the victim's body may suffer flash burns from arcing resulting in extensive scattered or confluent heat damage of the skin. In such cases, the nail plates of fingers and toes may undergo thermal changes which up to now have not been mentioned in the pertinent literature. Macroscopically, the nail shows a yellowish discoloration with tiny and closely arranged verruciform elevations. Histologically, the uppermost layer of the nail plate is interspersed with small vacuoles resembling micro-blisters as seen in the corneal layer of common electric marks. The surface of the nail is coated with a thin film of carbonaceous material. Based on an accidental high-voltage electrocution recently observed by the authors, attention is also drawn to the possible occurrence of contact burns from metal objects heated by the current as this finding is usually described only in victims of lightning strikes and not in the context of high-voltage discharges of technical electricity.

  18. Formation of clustered DNA damage after high-LET irradiation: a review.

    PubMed

    Hada, Megumi; Georgakilas, Alexandros G

    2008-05-01

    Radiation can cause as well as cure cancer. The risk of developing radiation-induced cancer has traditionally been estimated from cancer incidence among survivors of the atomic bombs in Hiroshima and Nagasaki.(1)) These data provide the best estimate of human cancer risk over the dose range for low linear energy transfer (LET) radiations, such as X- or gamma-rays. The situation of estimating the real biological effects becomes even more difficult in the case of high LET particles encountered in space or as the result of domestic exposure to alpha-particles from radon gas emitters or other radioactive emitters like uranium-238. Complex DNA damage, i.e., the signature of high-LET radiations comprises of closely spaced DNA lesions forming a cluster of DNA damage. The two basic groups of complex DNA damage are double strand breaks (DSBs) and non-DSB oxidative clustered DNA lesions (OCDL). Theoretical analysis and experimental evidence suggest an increased complexity and severity of complex DNA damage with increasing LET (linear energy transfer) and a high mutagenic or carcinogenic potential. Data available on the formation of clustered DNA damage (DSBs and OCDL) by high-LET radiations are often controversial suggesting a variable response to dose and type of radiation. The chemical nature and cellular repair mechanisms of complex DNA damage have been much less characterized than those of isolated DNA lesions like an oxidized base or a single strand break especially in the case of high-LET radiation. This review will focus on the induction of clustered DNA damage by high-LET radiations presenting the earlier and recent relative data.

  19. Formation of Clustered DNA Damage after High-LET Irradiation: A Review

    NASA Technical Reports Server (NTRS)

    Hada, Megumi; Georgakilas, Alexandros G.

    2008-01-01

    Radiation can cause as well as cure cancer. The risk of developing radiation-induced cancer has traditionally been estimated from cancer incidence among survivors of the atomic bombs in Hiroshima and Nagasaki. These data provide the best estimate of human cancer risk over the dose range for low linear energy transfer (LET) radiations, such as X- or gamma-rays. The situation of estimating the real biological effects becomes even more difficult in the case of high LET particles encountered in space or as the result of domestic exposure to particles from radon gas emitters or other radioactive emitters like uranium-238. Complex DNA damage, i.e., the signature of high-LET radiations comprises by closely spaced DNA lesions forming a cluster of DNA damage. The two basic groups of complex DNA damage are double strand breaks (DSBs) and non-DSB oxidative clustered DNA lesions (OCDL). Theoretical analysis and experimental evidence suggest there is increased complexity and severity of complex DNA damage with increasing LET (linear energy transfer) and a high mutagenic or carcinogenic potential. Data available on the formation of clustered DNA damage (DSBs and OCDL) by high-LET radiations are often controversial suggesting a variable response to dose and type of radiation. The chemical nature and cellular repair mechanisms of complex DNA damage have been much less characterized than those of isolated DNA lesions like an oxidized base or a single strand break especially in the case of high-LET radiation. This review will focus on the induction of clustered DNA damage by high-LET radiations presenting the earlier and recent relative data.

  20. [Recombinant Trichinella spiralis-53000 protein alleviates liver damage due to lipopolysaccharides via M2 macrophage activation].

    PubMed

    Chen, Zhibin; Tang, Hao; Li, Zhenyu; Liang, Yanbing; Wu, Jingguo; Zeng, Lijin; Yang, Qing; Liang, Huaping; Ma, Zhongfu

    2014-08-01

    To evaluate if recombinant Trichinella spiralis-53 000 protein (rTsP53) could alleviate liver damage caused by lipopolysaccharides (LPS) via M2 macrophage activation. Sixty male BALB/c mice were randomly divided into LPS group, LPS + phosphate buffer saline (PBS) group and rTsP53 intervention group by random number table, with 20 mice in each group. Intraperitoneal injection of 15 μg/kg LPS was performed for all the mice in the three groups after 8 hours of fasting. The mice in LPS + PBS group were injected with PBS after 1 hour of LPS injection. The mice in the rTsP53 intervention group were injected with rTsP53 (5 mg/kg) after 1 hour of LPS injection. After 48 hours all the mice were sacrificed. Peritoneal macrophages were harvested and flow cytometry (FCM) was used to detect markers CCR7 (M1) and CD206 (M2) of macrophages. Hepatic tissue was harvested for pathological study after hematoxylin-eosin (HE) staining, and double staining immunofluorescence was used to detect F4/80⁺ HLA-DR⁺ and F4/80⁺ CD163⁺. Peripheral blood serum was harvested to detect the levels of aspartate transaminase (AST) and alanine transaminase (ALT). Compared with LPS and LPS + PBS groups, survival rate of mice of rTsP53 intervention group was significantly elevated (90% vs. 25%, 30%, both P<0.01), and the pathological injury of the liver was significantly ameliorated, and the hepatic structure was better preserved. The transaminase in rTsP53 intervention group was significantly lower than that of LPS and LPS + PBS groups (ALT: 97.7 ± 8.5 U/L vs. 181.7 ± 19.5 U/L, 173.7 ± 17.2 U/L; AST: 142.7 ± 12.1 U/L vs. 235.7 ± 9.9 U/L, 213.7 ± 6.7 U/L, all P<0.05), FITC-CD206⁺ proportion of peritoneal macrophage was significantly higher [(17.75 ± 0.30)% vs. (1.38 ± 0.13)%, (1.36 ± 0.05)%, both P<0.05] while PE-CCR7(+) proportion [(6.89 ± 0.11)% vs. (15.30 ± 0.64)%, (14.96 ± 0.93)%, both P<0.05] was significantly lower. Fluorescence intensity of macrophages with F4/80⁺ CD163

  1. Cardiotoxic (Arrhythmogenic) Effects of 1,1-Difluoroethane Due to Electrolyte Imbalance and Cardiomyocyte Damage.

    PubMed

    Joshi, Kaushal; Barletta, Michael; Wurpel, John

    2017-03-03

    Inhalant abuse is the intentional inhalation of chemical vapors to attain euphoric effects. Many common household products are abused by inhalation and one is 1,1-difluoroethane (DFE), which is a halogenated hydrocarbon used in refrigeration, dust-off spray, and airbrush painting. Although many human DFE abuse cases have been studied, the etiology and mechanism of sudden death is still unknown. In this study, an animal model was used to simulate the human conditions of DFE inhalation abuse that results in sudden death.Current research targets mechanistic studies involving electrolyte changes and cardiomyocyte damage after DFE administration in vivo. To investigate these changes, Sprague Dawley rats (N = 6) were exposed to 30 seconds of 20 L/min of DFE in multiple doses. Isoflurane acted as a control. Two additional groups, epinephrine and epinephrine + DFE, were included to simulate the clinical condition of DFE abuse. Plasma sodium, potassium, calcium, and magnesium levels were measured, followed by lactate dehydrogenase, creatine kinase, and cardiac troponin I levels. In addition, oxidative stress markers were also evaluated in all animal groups. Electrolyte levels showed a significant rise in plasma potassium and magnesium levels for the treated groups. In addition, lactate dehydrogenase, creatine kinase, and cardiac troponin I levels in DFE and epinephrine + DFE administered rats were significantly elevated as compared with control. Some oxidative stress makers were also elevated significantly in treatment groups. Furthermore, histopathological analysis showed hyperemia/congestion in treated rats.These results support cardiotoxic effects indicating that DFE results in fatal arrhythmias, and the study can be important during clinical cases involving inhalant abuse.

  2. Estimation of the Past and Future Infrastructure Damage Due the Permafrost Evolution Processes

    NASA Astrophysics Data System (ADS)

    Sergeev, D. O.; Chesnokova, I. V.; Morozova, A. V.

    2015-12-01

    The geocryological processes such as thermokarst, frost heaving and fracturing, icing, thermal erosion are the source of immediate danger for the structures. The economic losses during the construction procedures in the permafrost area are linked also with the other geological processes that have the specific character in cold regions. These processes are swamping, desertification, deflation, flooding, mudflows and landslides. Linear transport structures are most vulnerable component of regional and national economy. Because the high length the transport structures have to cross the landscapes with different permafrost conditions that have the different reaction to climate change. The climate warming is favorable for thermokarst and the frost heaving is linked with climate cooling. In result the structure falls in the circumstances that are not predicted in the construction project. Local engineering problems of structure exploitation lead to global risks of sustainable development of regions. Authors developed the database of geocryological damage cases for the last twelve years at the Russian territory. Spatial data have the attributive table that was filled by the published information from various permafrost conference proceedings. The preliminary GIS-analysis of gathered data showed the widespread territorial distribution of the cases of negative consequences of geocryological processes activity. The information about maximum effect from geocryological processes was validated by detailed field investigation along the railways in Yamal and Transbaicalia Regions. Authors expect the expanding of database by similar data from other sectors of Arctic. It is important for analyzing the regional, time and industrial tendencies of geocryological risk evolution. Obtained information could be used in insurance procedures and in information systems of decisions support in different management levels. The investigation was completed with financial support by Russian

  3. Valuation of damages to recreational trout fishing in the Upper Northeast due to acidic deposition

    SciTech Connect

    Englin, J.E.; Cameron, T.A.; Mendelsohn, R.E.; Parsons, G.A.; Shankle, S.A.

    1991-04-01

    This report documents methods used to estimate economic models of changes in recreational fishing due to the acidic deposition. The analysis was conducted by Pacific Northwest Laboratory (PNL) and its subcontractors for the US Environmental Protection Agency (EPA) and the US Department of Energy (DOE) in support of the National Acidic Precipitation Assessment Program (NAPAP). The primary data needed to estimate these models were collected in the 1989 Aquatic Based Recreation Survey (ABRS), which was jointly funded by the DOE and the EPA's Office of Policy Planning and Evaluation. 11 refs., 5 figs., 15 tabs.

  4. Damaged Neocortical Perineuronal Nets Due to Experimental Focal Cerebral Ischemia in Mice, Rats and Sheep.

    PubMed

    Härtig, Wolfgang; Mages, Bianca; Aleithe, Susanne; Nitzsche, Björn; Altmann, Stephan; Barthel, Henryk; Krueger, Martin; Michalski, Dominik

    2017-01-01

    As part of the extracellular matrix (ECM), perineuronal nets (PNs) are polyanionic, chondroitin sulfate proteoglycan (CSPG)-rich coatings of certain neurons, known to be affected in various neural diseases. Although these structures are considered as important parts of the neurovascular unit (NVU), their role during evolution of acute ischemic stroke and subsequent tissue damage is poorly understood and only a few preclinical studies analyzed PNs after acute ischemic stroke. By employing three models of experimental focal cerebral ischemia, this study was focused on histopathological alterations of PNs and concomitant vascular, glial and neuronal changes according to the NVU concept. We analyzed brain tissues obtained 1 day after ischemia onset from: (a) mice after filament-based permanent middle cerebral artery occlusion (pMCAO); (b) rats subjected to thromboembolic MACO; and (c) sheep at 14 days after electrosurgically induced focal cerebral ischemia. Multiple fluorescence labeling was applied to explore simultaneous alterations of NVU and ECM. Serial mouse sections labeled with the net marker Wisteria floribunda agglutinin (WFA) displayed largely decomposed and nearly erased PNs in infarcted neocortical areas that were demarcated by up-regulated immunoreactivity for vascular collagen IV (Coll IV). Subsequent semi-quantitative analyses in mice confirmed significantly decreased WFA-staining along the ischemic border zone and a relative decrease in the directly ischemia-affected neocortex. Triple fluorescence labeling throughout the three animal models revealed up-regulated Coll IV and decomposed PNs accompanied by activated astroglia and altered immunoreactivity for parvalbumin, a calcium-binding protein in fast-firing GABAergic neurons which are predominantly surrounded by neocortical PNs. Furthermore, ischemic neocortical areas in rodents simultaneously displayed less intense staining of WFA, aggrecan, the net components neurocan, versican and the cartilage link

  5. Bulk damage and absorption in fused silica due to high-power laser applications

    NASA Astrophysics Data System (ADS)

    Nürnberg, F.; Kühn, B.; Langner, A.; Altwein, M.; Schötz, G.; Takke, R.; Thomas, S.; Vydra, J.

    2015-11-01

    Laser fusion projects are heading for IR optics with high broadband transmission, high shock and temperature resistance, long laser durability, and best purity. For this application, fused silica is an excellent choice. The energy density threshold on IR laser optics is mainly influenced by the purity and homogeneity of the fused silica. The absorption behavior regarding the hydroxyl content was studied for various synthetic fused silica grades. The main absorption influenced by OH vibrational excitation leads to different IR attenuations for OH-rich and low-OH fused silica. Industrial laser systems aim for the maximum energy extraction possible. Heraeus Quarzglas developed an Yb-doped fused silica fiber to support this growing market. But the performance of laser welding and cutting systems is fundamentally limited by beam quality and stability of focus. Since absorption in the optical components of optical systems has a detrimental effect on the laser focus shift, the beam energy loss and the resulting heating has to be minimized both in the bulk materials and at the coated surfaces. In collaboration with a laser research institute, an optical finisher and end users, photo thermal absorption measurements on coated samples of different fused silica grades were performed to investigate the influence of basic material properties on the absorption level. High purity, synthetic fused silica is as well the material of choice for optical components designed for DUV applications (wavelength range 160 nm - 260 nm). For higher light intensities, e.g. provided by Excimer lasers, UV photons may generate defect centers that effect the optical properties during usage, resulting in an aging of the optical components (UV radiation damage). Powerful Excimer lasers require optical materials that can withstand photon energy close to the band gap and the high intensity of the short pulse length. The UV transmission loss is restricted to the DUV wavelength range below 300 nm and

  6. Hypochlorite-induced damage to nucleosides: formation of chloramines and nitrogen-centered radicals.

    PubMed

    Hawkins, C L; Davies, M J

    2001-08-01

    Stimulated monocytes and neutrophils generate hypochlorite (HOCl) via the release of the enzyme myeloperoxidase and hydrogen peroxide. HOCl is a key bactericidal agent, but can also damage host tissue. As there is a strong link between chronic inflammation and some cancers, we have investigated HOCl damage to DNA bases. We show that reaction of HOCl with the exocyclic -NH(2) groups of cytidine, adenosine, and guanosine, and the ring NH groups of all bases, yields chloramines (RNHCl/RR'NCl). These are the major initial products. Chloramine decay can be accelerated by UV light and metal ions, and these reactions, together with thermal decomposition, give rise to nucleoside-derived nitrogen-centered radicals. Evidence is presented for the rapid addition of pyrimidine-derived nitrogen-centered radicals to another parent molecule to give dimers. Experiments with nucleoside mixtures show that the propensity for radical formation is cytidine > adenosine = guanosine > uridine = thymidine. These data are inconsistent with the selectivity of HOCl attack and the stability of the resulting chloramines, but can be rationalized if chlorine transfer between bases is rapid and yields the most stable chloramine, with such transfer preceding radical formation. Thus, though thymidine is the major initial site of chloramine formation, rapid chlorine atom transfer generates cytidine and adenosine chloramines. These reactions rationalize the preferential formation of chlorinated cytidine and adenosine in DNA.

  7. Pessimum effect of externally applied chlorides on expansion due to delayed ettringite formation: Proposed mechanism

    SciTech Connect

    Ekolu, S.O. . E-mail: s.ekolu@utoronto.ca; Thomas, M.D.A.; Hooton, R.D.

    2006-04-15

    Mortars and concretes were subjected to a heat treatment cycle consisting of a pre-set period of 4 h at 23 deg. C followed by accelerated curing at 95 deg. C prior to storage at room temperature in water or limewater, 0.5 M, 2.8 M sodium chloride solutions. It was found that the specimens stored in 0.5 M sodium chloride solution gave a much greater expansion than those stored in limewater or 2.8 M sodium chloride solution. This pessimum influence of chlorides on expansion due to delayed ettringite formation deviates from the commonly held view that chlorides mitigate sulphate attack in concretes. The mechanism of the pessimum effect of chlorides on expansion due to delayed ettringite formation, and the final products of the associated phase transformations have been proposed. X-ray diffraction and differential thermal analysis techniques were used to follow phase transformations.

  8. Geodynamically unusual settings of sedimentary rock and ore formation due to tectonic-decompression effects

    SciTech Connect

    Goryainov, P.M.

    1984-05-01

    The traditional views of terrigenous rocks as products of classical sedimentary cycle, ''mobilization-transport-deposition,'' are not universal. Detrital rocks are sometimes formed due to flaking and fracturation of rocks of rising blocks. The process is produced by tectonic-decompression mechanisms - the origination of a gradient of excessive stress and its discharge. It is incorrect to classify rocks created by this phenomenon with weathering crusts. The origins of certain terrigenous rocks, as well as products of low-temperature chemical processing, are connected with deep-volume decompression (brecciation, stockwork formation, formation of pipes and columns of igneous rocks, and chamber pegmatite and karst formation). The ore concentrations associated with such entities and appearing as stratiform deposits are most likely not exogenous, but they complete the endogenous history of the block concerned. The means and methods tested on typical endogenous deposits may therefore prove valuable in predicting certain varieties of stratiform deposits.

  9. [Formation causes of wind damage to Robinia pseudoacacia plantation in Yellow River Delta].

    PubMed

    Cao, Bang-Hua; Zhang, Yu-Juan; Mao, Pei-Li; Li, Cheng-Bo

    2012-08-01

    Based on the investigation of the gale-caused damage to the Robinia pseudoacacia plantation in the Yellow River Delta in June-July 2010, this paper measured the morphological indexes and root system characteristics of fallen trees, gap sizes, and soil compactness, aimed to analyze the formation causes of the wind damage to the plantation. Wind-falling was the main form of the wind damage to the R. pseudoacacia plantation, and the damage was more serious for the trees with the diameter at breast height of 15-20 cm. For the fallen trees, their tree height and their crown width, height, and taper degree increased significantly with the increase of the diameter at breast height, while the height under branch, the ratio of crown width to height, and the ratio of the height under branch to tree height showed no significant change. With the increase of diameter class, root length had a rapid increase first but a slow increase then, while root mass increased gradually. With increasing forest gap area, the number of fallen trees decreased after an initial increase, being the maximum in the gap areas of 100-150 m2. Soil compactness increased with soil depth, but did not show significant changes with the stand diameter class. Increased tree shape factors and suppressed root growth resulting from the increased diameter could be the main factors causing wind-falling, and forest gap played a promotion role.

  10. Cellular responses and gene expression profile changes due to bleomycin-induced DNA damage in human fibroblasts in space

    PubMed Central

    Kidane, Yared; Feiveson, Alan; Stodieck, Louis; Karouia, Fathi; Ramesh, Govindarajan; Rohde, Larry; Wu, Honglu

    2017-01-01

    Living organisms in space are constantly exposed to radiation, toxic chemicals or reactive oxygen species generated due to increased levels of environmental and psychological stresses. Understanding the impact of spaceflight factors, microgravity in particular, on cellular responses to DNA damage is essential for assessing the radiation risk for astronauts and the mutation rate in microorganisms. In a study conducted on the International Space Station, confluent human fibroblasts in culture were treated with bleomycin for three hours in the true microgravity environment. The degree of DNA damage was quantified by immunofluorescence staining for γ-H2AX, which is manifested in three types of staining patterns. Although similar percentages of these types of patterns were found between flight and ground cells, there was a slight shift in the distribution of foci counts in the flown cells with countable numbers of γ-H2AX foci. Comparison of the cells in confluent and in exponential growth conditions indicated that the proliferation rate between flight and the ground may be responsible for such a shift. We also performed a microarray analysis of gene expressions in response to bleomycin treatment. A qualitative comparison of the responsive pathways between the flown and ground cells showed similar responses with the p53 network being the top upstream regulator. The microarray data was confirmed with a PCR array analysis containing a set of genes involved in DNA damage signaling; with BBC3, CDKN1A, PCNA and PPM1D being significantly upregulated in both flight and ground cells after bleomycin treatment. Our results suggest that whether microgravity affects DNA damage response in space can be dependent on the cell type and cell growth condition. PMID:28248986

  11. Semiconductor structural damage attendant to contact formation in III-V solar cells

    NASA Technical Reports Server (NTRS)

    Fatemi, Navid S.; Weizer, Victor G.

    1991-01-01

    In order to keep the resistive losses in solar cells to a minimum, it is often necessary for the ohmic contacts to be heat treated to lower the metal-semiconductor contact resistivity to acceptable values. Sintering of the contacts, however can result in extensive mechanical damage of the semiconductor surface under the metallization. An investigation of the detailed mechanisms involved in the process of contact formation during heat treatment may control the structural damage incurred by the semiconductor surface to acceptable levels, while achieving the desired values of contact resistivity for the ohmic contacts. The reaction kinetics of sintered gold contacts to InP were determined. It was found that the Au-InP interaction involves three consecutive stages marked by distinct color changes observed on the surface of the Au, and that each stage is governed by a different mechanism. A detailed description of these mechanisms and options to control them are presented.

  12. ASCIZ regulates lesion-specific Rad51 focus formation and apoptosis after methylating DNA damage

    PubMed Central

    McNees, Carolyn J; Conlan, Lindus A; Tenis, Nora; Heierhorst, Jörg

    2005-01-01

    Nuclear Rad51 focus formation is required for homology-directed repair of DNA double-strand breaks (DSBs), but its regulation in response to non-DSB lesions is poorly understood. Here we report a novel human SQ/TQ cluster domain-containing protein termed ASCIZ that forms Rad51-containing foci in response to base-modifying DNA methylating agents but not in response to DSB-inducing agents. ASCIZ foci seem to form prior to Rad51 recruitment, and an ASCIZ core domain can concentrate Rad51 in focus-like structures independently of DNA damage. ASCIZ depletion dramatically increases apoptosis after methylating DNA damage and impairs Rad51 focus formation in response to methylating agents but not after ionizing radiation. ASCIZ focus formation and increased apoptosis in ASCIZ-depleted cells depend on the mismatch repair protein MLH1. Interestingly, ASCIZ foci form efficiently during G1 phase, when sister chromatids are unavailable as recombination templates. We propose that ASCIZ acts as a lesion-specific focus scaffold in a Rad51-dependent pathway that resolves cytotoxic repair intermediates, most likely single-stranded DNA gaps, resulting from MLH1-dependent processing of base lesions. PMID:15933716

  13. ASCIZ regulates lesion-specific Rad51 focus formation and apoptosis after methylating DNA damage.

    PubMed

    McNees, Carolyn J; Conlan, Lindus A; Tenis, Nora; Heierhorst, Jörg

    2005-07-06

    Nuclear Rad51 focus formation is required for homology-directed repair of DNA double-strand breaks (DSBs), but its regulation in response to non-DSB lesions is poorly understood. Here we report a novel human SQ/TQ cluster domain-containing protein termed ASCIZ that forms Rad51-containing foci in response to base-modifying DNA methylating agents but not in response to DSB-inducing agents. ASCIZ foci seem to form prior to Rad51 recruitment, and an ASCIZ core domain can concentrate Rad51 in focus-like structures independently of DNA damage. ASCIZ depletion dramatically increases apoptosis after methylating DNA damage and impairs Rad51 focus formation in response to methylating agents but not after ionizing radiation. ASCIZ focus formation and increased apoptosis in ASCIZ-depleted cells depend on the mismatch repair protein MLH1. Interestingly, ASCIZ foci form efficiently during G1 phase, when sister chromatids are unavailable as recombination templates. We propose that ASCIZ acts as a lesion-specific focus scaffold in a Rad51-dependent pathway that resolves cytotoxic repair intermediates, most likely single-stranded DNA gaps, resulting from MLH1-dependent processing of base lesions.

  14. The effect of green tea on oxidative damage and tumour formation in Lobund-Wistar rats.

    PubMed

    O'Sullivan, Jacintha; Sheridan, Juliette; Mulcahy, Hugh; Tenniswood, Martin; Morrissey, Colm

    2008-11-01

    A number of epidemiological studies suggest that the consumption of green tea reduces the incidence of prostate cancer. As the major catechins present in green tea are potent antioxidants, we hypothesized that genetic and cellular damage induced by oxygen free radicals could be significantly reduced by potent antioxidants in green tea, thus reducing the cumulative genetic and cellular damage with age, and slowing or preventing tumour formation. Long-term administration of a decaffeinated green tea extract to Lobund-Wistar rats for periods up to 26 months almost halved the incidence of primary tumours in the genitourinary tract when compared with an age-matched cohort receiving just water. We observed no inhibition of DNA adduct formation or lipid peroxidation in animals consuming green tea compared with animals consuming deionized water. The decrease in tumour formation was associated with an increase in 8-hydroxy-2'deoxyguanosine and 4-hydroxynonenal content (markers of DNA adduct formation and lipid peroxidation, respectively) in the epithelium of the ventral prostate in aging animals. In addition, there was an increase in 8-hydroxy-2'deoxyguanosine expression, but no change in 4-hydroxynonenal expression in the seminal vesicles of older animals. An age-associated increase in expression of the antioxidant enzymes manganese superoxide dismutase and catalase in the epithelium of the ventral prostate of aging animals was observed. Furthermore, there was also an increase in manganese superoxide dismutase expression, but no change in catalase expression in the seminal vesicles of older animals. These data demonstrate that consumption of green tea decreases the incidence of genitourinary tract tumours in the Lobund-Wistar rat, but has no effect on age-associated DNA adduct formation and lipid peroxidation in the ventral prostate and seminal vesicles of the aging rat.

  15. Diamond formation due to a pH drop during fluid–rock interactions

    PubMed Central

    Sverjensky, Dimitri A.; Huang, Fang

    2015-01-01

    Diamond formation has typically been attributed to redox reactions during precipitation from fluids or magmas. Either the oxidation of methane or the reduction of carbon dioxide has been suggested, based on simplistic models of deep fluids consisting of mixtures of dissolved neutral gas molecules without consideration of aqueous ions. The role of pH changes associated with water–silicate rock interactions during diamond formation is unknown. Here we show that diamonds could form due to a drop in pH during water–rock interactions. We use a recent theoretical model of deep fluids that includes ions, to show that fluid can react irreversibly with eclogite at 900 °C and 5.0 GPa, generating diamond and secondary minerals due to a decrease in pH at almost constant oxygen fugacity. Overall, our results constitute a new quantitative theory of diamond formation as a consequence of the reaction of deep fluids with the rock types that they encounter during migration. Diamond can form in the deep Earth during water–rock interactions without changes in oxidation state. PMID:26529259

  16. Diamond formation due to a pH drop during fluid–rock interactions

    SciTech Connect

    Sverjensky, Dimitri A.; Huang, Fang

    2015-11-03

    Diamond formation has typically been attributed to redox reactions during precipitation from fluids or magmas. Either the oxidation of methane or the reduction of carbon dioxide has been suggested, based on simplistic models of deep fluids consisting of mixtures of dissolved neutral gas molecules without consideration of aqueous ions. The role of pH changes associated with water–silicate rock interactions during diamond formation is unknown. Here we show that diamonds could form due to a drop in pH during water–rock interactions. We use a recent theoretical model of deep fluids that includes ions, to show that fluid can react irreversibly with eclogite at 900 °C and 5.0 GPa, generating diamond and secondary minerals due to a decrease in pH at almost constant oxygen fugacity. Overall, our results constitute a new quantitative theory of diamond formation as a consequence of the reaction of deep fluids with the rock types that they encounter during migration. Diamond can form in the deep Earth during water–rock interactions without changes in oxidation state.

  17. Diamond formation due to a pH drop during fluid–rock interactions

    DOE PAGES

    Sverjensky, Dimitri A.; Huang, Fang

    2015-11-03

    Diamond formation has typically been attributed to redox reactions during precipitation from fluids or magmas. Either the oxidation of methane or the reduction of carbon dioxide has been suggested, based on simplistic models of deep fluids consisting of mixtures of dissolved neutral gas molecules without consideration of aqueous ions. The role of pH changes associated with water–silicate rock interactions during diamond formation is unknown. Here we show that diamonds could form due to a drop in pH during water–rock interactions. We use a recent theoretical model of deep fluids that includes ions, to show that fluid can react irreversibly withmore » eclogite at 900 °C and 5.0 GPa, generating diamond and secondary minerals due to a decrease in pH at almost constant oxygen fugacity. Overall, our results constitute a new quantitative theory of diamond formation as a consequence of the reaction of deep fluids with the rock types that they encounter during migration. Diamond can form in the deep Earth during water–rock interactions without changes in oxidation state.« less

  18. Telomeres in ICF syndrome cells are vulnerable to DNA damage due to elevated DNA:RNA hybrids

    PubMed Central

    Sagie, Shira; Toubiana, Shir; Hartono, Stella R.; Katzir, Hagar; Tzur-Gilat, Aya; Havazelet, Shany; Francastel, Claire; Velasco, Guillaume; Chédin, Frédéric; Selig, Sara

    2017-01-01

    DNA:RNA hybrids, nucleic acid structures with diverse physiological functions, can disrupt genome integrity when dysregulated. Human telomeres were shown to form hybrids with the lncRNA TERRA, yet the formation and distribution of these hybrids among telomeres, their regulation and their cellular effects remain elusive. Here we predict and confirm in several human cell types that DNA:RNA hybrids form at many subtelomeric and telomeric regions. We demonstrate that ICF syndrome cells, which exhibit short telomeres and elevated TERRA levels, are enriched for hybrids at telomeric regions throughout the cell cycle. Telomeric hybrids are associated with high levels of DNA damage at chromosome ends in ICF cells, which are significantly reduced with overexpression of RNase H1. Our findings suggest that abnormally high TERRA levels in ICF syndrome lead to accumulation of telomeric hybrids that, in turn, can result in telomeric dysfunction. PMID:28117327

  19. Analysis of linear elasticity and non-linearity due to plasticity and material damage in woven and biaxial braided composites

    NASA Astrophysics Data System (ADS)

    Goyal, Deepak

    Textile composites have a wide variety of applications in the aerospace, sports, automobile, marine and medical industries. Due to the availability of a variety of textile architectures and numerous parameters associated with each, optimal design through extensive experimental testing is not practical. Predictive tools are needed to perform virtual experiments of various options. The focus of this research is to develop a better understanding of linear elastic response, plasticity and material damage induced nonlinear behavior and mechanics of load flow in textile composites. Textile composites exhibit multiple scales of complexity. The various textile behaviors are analyzed using a two-scale finite element modeling. A framework to allow use of a wide variety of damage initiation and growth models is proposed. Plasticity induced non-linear behavior of 2x2 braided composites is investigated using a modeling approach based on Hill's yield function for orthotropic materials. The mechanics of load flow in textile composites is demonstrated using special non-standard postprocessing techniques that not only highlight the important details, but also transform the extensive amount of output data into comprehensible modes of behavior. The investigations show that the damage models differ from each other in terms of amount of degradation as well as the properties to be degraded under a particular failure mode. When compared with experimental data, predictions of some models match well for glass/epoxy composite whereas other's match well for carbon/epoxy composites. However, all the models predicted very similar response when damage factors were made similar, which shows that the magnitude of damage factors are very important. Full 3D as well as equivalent tape laminate predictions lie within the range of the experimental data for a wide variety of braided composites with different material systems, which validated the plasticity analysis. Conclusions about the effect of

  20. Ventriculoperitoneal shunt blockage due to spontaneous knot formation in the peritoneal catheter. Case report.

    PubMed

    Eftekhar, Behzad; Hunn, Andrew

    2008-02-01

    The authors report the third case of ventriculoperitoneal shunt blockage due to spontaneous knot formation in the peritoneal catheter that had been placed in a 3.5-year-old boy 8 months earlier. On surgical exploration a double knot was found 10 cm from the distal end of the peritoneal catheter. Although the underlying mechanism remains unknown, the authors used the analogy of related physical studies and true knot formation in the umbilical cord and determined the possible causes as related to the catheter, volume and configuration of the abdomen, and kinetics of the catheter movements. If further study should reveal a significantly higher incidence of this complication, the authors suggest further in vitro studies, designed to investigate the optimal characteristics and safe range of length of peritoneal catheters in different situations.

  1. Prediction of subsidence: Relationship between lowering of formation pressure and subsidence due to fluid withdrawal

    SciTech Connect

    Serebryakov, V.A.; Chilingar, G.V.

    2000-06-01

    Abnormally low formation pressures develop in petroleum reservoirs during intensive oil and gas production or in aquifers as a result of water extraction. A simple method is presented for calculating (predicting) the amount of compaction (and resulting subsidence) from the pressure drop in formation due to production, i.e., the increase in the effective pressure p{sub e} (p{sub e} = p{sub t} {minus} p{sub p}, where p{sub t} is the total overburden pressure and p{sub p} is the fluid or pore pressure). This work is based on extensive data collected in Russia. For example, large petroliferous areas in Western Siberia became marshlands as a result of fluid withdrawal. One should remember that sophisticated methods, such as FSMT (direct measurement of rock compaction by wireline tools in situ) and GPS (measurement of surface subsidence by satellite microwave Doppler techniques), are not yet available in many areas of the world.

  2. Chemical aspects of iron colloid plugging in quartz sands and implications for formation damage

    SciTech Connect

    Potter, J.M.; Dibble, W.E.

    1985-09-01

    A research direction having great potential for better understanding of formation damage is the influence of colloid plugging on fluid flow behavior in porous media. Using flow through experimental equipment, we have explored the dependence of the degree of ferric oxyhydroxide colloid plugging of quartz sand packs on the solution pH and anion type at a constant temperature of 208/sup 0/F (97.7/sup 0/C). At a pH of 5, permeability reductions were greatest in the order PO/sup 3//sub 4/-, SO/sup 2//sub 4/-, and Cl-. This order was reversed at a pH of 9. The results suggest that plugging occurs by two fundamentally different mechanisms. First, flocculation/coagulation of the ferric hydroxide leads to formation of filter cake in the low-pH case. Second, colloid/quartz surface interaction produces a more uniform accumulation of colloid throughout the core at higher pH's.

  3. Dynamics of seed magnetic island formation due to geometrically coupled perturbations

    SciTech Connect

    Hegna, C.C.; Callen, J.D.; LaHaye, R.J.

    1998-06-01

    Seed magnetic island formation due to a dynamically growing external source in toroidal confinement devices is modeled as an initial value forced reconnection problem. For an external source whose amplitude grows on a time scale quickly compared to the Sweet-Parker time of resistive magnetohydrodynamics, the induced reconnection is characterized by a current sheet and a reconnected flux amplitude which lags in time the source amplitude. This suggests that neoclassical tearing modes, whose excitation requires a seed magnetic island, are more difficult to cause in high Lundquist number plasmas.

  4. Microcolumn Formation due to Induced-Charge Electroosmosis in a Floating Mode

    NASA Astrophysics Data System (ADS)

    Sugioka, Hideyuki; Dan, Hironobu; Hanazawa, Yuya

    2017-10-01

    Self-organization of particles is important since it may provide new functional materials. Previously, by using two-dimensional multiphysics simulations, we theoretically showed microcolumn formation due to induced-charge electroosmosis (ICEO). In this study, we experimentally demonstrate that gold leaves on a water surface move slowly and dynamically form a microcolumn due to a hydrodynamic interaction under an ac electric field. Further, by numerically analyzing video data, we show the time evolutions of the maximum cluster length and the maximum cluster area. In addition, by cluster analysis, we show the dependences of the average velocity on the applied voltage and frequency to clarify the phenomena. We believe that our findings make a new stage in the development of new functional materials on a water surface.

  5. Advances in detecting localized road damage due to sinkholes induced by engineering works using high resolution RASARSAT-2 data

    NASA Astrophysics Data System (ADS)

    Chen, J.; Zebker, H. A.; Lakshmi, V.

    2016-12-01

    Sinkholes often occur in karst terrains such as found in central and eastern Pennsylvania. Voids produced by dissolution of carbonate rocks can result in soil transport leading to localized, gradual or rapid, sinking of the land surface. A cluster of sinkholes developed in 2000 around a small rural community beside Bushkill creek near a limestone quarry, and severely destroyed road bridges and railway tracks. At a cost of $6 million, the Pennsylvania DoT replaced the bridge, which was damaged again in 2004 by newly developed sinkholes likely associated with quarry's pumping activity. Here we present high-resolution spaceborne interferometric radar images of sinkhole development on this community. We show that this technique may be used to monitor regions with high sinkhole damage risk and assist future infrastructure route planning, especially in rural areas where hydrogeologic information is limited. Specifically, we processed 66 RADARSAT-2 interferograms to extract deformation occurred over Bushkill creek between Jun. 2015 and Mar. 2016 with a temporal resolution of 24 days. We advanced recent persistent scatterer techniques to preserve meter-level spatial resolution in the interferograms while minimizing temporal decorrelation and phase unwrapping error. We observe periodic deformation due to pumping activity at the quarry and localized subsidence along Bushkill creek that is co-located with recent reported sinkholes. We plan to use the automatic processing techniques developed for this study to study road damage in another region in Pennsylvania, along Lewiston Narrows, and also to monitor urban infrastructure improvements in Seattle, both again with RASARSAT-2 data. Our results demonstrate that recent advances in satellite geodesy can be transferred to benefit society beyond the science community.

  6. Endogenous alpha-oxoaldehydes and formation of protein and nucleotide advanced glycation endproducts in tissue damage.

    PubMed

    Thornalley, Paul J

    2007-01-01

    Human and other biological tissues face a continual threat of damage by alpha-oxoaldehydes formed endogenously. Glyoxal, methylglyoxal and 3-deoxyglucosone are formed by the degradation of glycolytic intermediates, glycated proteins and lipid peroxidation. They are potent glycating agents of protein and nucleotides leading to the formation of advanced glycation endproducts (AGEs). With proteins, they are arginine residue-directed glycating agents forming mainly hydroimidazolones, found at 0.1-1% of total arginine residues in tissues (2-20% of proteins modified). With nucleotides, imidazopurinone- and N2-carboxyalkyl- derivatives of deoxyguanosine are formed, found at 0.1-0.8 per 10(6) nucleotides in DNA. Glycation occurs in all tissues and body fluids. Cellular proteolysis of AGE-modified proteins and DNA releases glycated amino acids and nucleosides. Glycated amino acids and nucleosides are released into plasma, undergo glomerular filtration and are excreted in urine. The damage to tissue protein and nucleotides by alpha-oxoaldehydes is suppressed by the metabolism of alpha-oxoaldehyde glycating agents by the glutathione-dependent enzyme, glyoxalase I, and aldo-keto reductases. These enzymatic activities are part of the enzymatic defence against glycation. Tissue damage by alpha-oxoaldehyde glycation is implicated in diabetic and non-diabetic vascular disease, renal failure, cirrhosis, Alzheimer's disease, arthritis and ageing.

  7. Peroxynitrite formation in nitric oxide-exposed submitochondrial particles: Detection, oxidative damage and catalytic removal by Mn-porphyrins

    PubMed Central

    Valez, Valeria; Cassina, Adriana; Batinic-Haberle, Ines; Kalyanaraman, Balaraman; Ferrer-Sueta, Gerardo; Radi, Rafael

    2012-01-01

    Peroxynitrite (ONOO−) formation in mitochondria may be favored due to the constant supply of superoxide radical (O2•−) by the electron transport chain plus the facile diffusion of nitric oxide (•NO) to this organelle. Herein, a model system of submitochondrial particles (SMP) in the presence of succinate plus the respiratory inhibitor antimycin A (to increase O2•− rates) and the •NO-donor NOC-7 was studied to directly establish and quantitate peroxynitrite by a multiplicity of methods including chemiluminescence, fluorescence and immunochemical analysis. While all the tested probes revealed peroxynitrite at near stoichiometric levels with respect to its precursor radicals, coumarin boronic acid (a probe that directly reacts with peroxynitrite) had the more straightforward oxidation profile from O2•−-forming SMP as a function of the •NO flux. Interestingly, immunospintrapping studies verified protein radical generation in SMP by peroxynitrite. Substrate-supplemented SMP also reduced Mn(III)porphyrins (MnP) to Mn(II)P under physiologically-relevant oxygen levels (3–30 μM); then, Mn(II)P were capable to reduce peroxynitrite and protect SMP from the inhibition of complex I-dependent oxygen consumption and protein radical formation and nitration of membranes. The data directly support the formation of peroxynitrite in mitochondria and demonstrate that MnP can undergo a catalytic redox cycle to neutralize peroxynitrite-dependent mitochondrial oxidative damage. PMID:23142682

  8. Modification of the Kozeny-Carman equation to quantify formation damage by fines in clean unconsolidated porous media

    NASA Astrophysics Data System (ADS)

    Krauss, Eva D.

    Accurately estimating formation permeability as a function of porosity, grain size, and the quantity and structure of fines is important for increasing hydrocarbon extraction from rock formations. Accurate formation permeability estimation can provide insight into the factors that lead to formation damage due to fines deposition. The Kozeny-Carman equation can be used to estimate the permeability of unconsolidated media as a function of porosity and grain size, but does not account for the structure of fines. In this study, I show how incorporating a dimensionless bulk factor into the Kozeny-Carman equation can be used to quantify the permeability reduction resulting from deposition of fines in the pore space. I consider several experimental studies from the literature that use a variety of porosities, fluids, fines (differentiated by diameter and type), porous media, and flow velocities. Results indicate that for all of the experiments analyzed, when other variables are held constant, experiments conducted at higher flow velocity result in less plugging. The bulk value was adjusted in the Kozeny-Carman equation to obtain a line of best fit. The root mean square method was used to obtain the best bulk factor value that calculated a curve which had the best match for the experimental data. Fitted values of the bulk factor were then correlated with the Peclet number to investigate how the structure of fines in the pore space, quantified by the bulk factor, depends on the characteristics of the porous media, the depositing colloids, and the flow velocity. For a particular experimental set, at a lower Peclet Number, higher bulk factors are observed, when diffusive transport dominates, which I speculate results from the presence of more dendritic deposits. At higher Peclet Numbers, lower bulk factors are observed, when advective transport dominates, which I speculate results from deposits that are more compact. By understanding the flow velocity dependence of

  9. Honey bee (Apis mellifera) drones survive oxidative stress due to increased tolerance instead of avoidance or repair of oxidative damage.

    PubMed

    Li-Byarlay, Hongmei; Huang, Ming Hua; Simone-Finstrom, Michael; Strand, Micheline K; Tarpy, David R; Rueppell, Olav

    2016-10-01

    Oxidative stress can lead to premature aging symptoms and cause acute mortality at higher doses in a range of organisms. Oxidative stress resistance and longevity are mechanistically and phenotypically linked; considerable variation in oxidative stress resistance exists among and within species and typically covaries with life expectancy. However, it is unclear whether stress-resistant, long-lived individuals avoid, repair, or tolerate molecular damage to survive longer than others. The honey bee (Apis mellifera L.) is an emerging model system that is well-suited to address this question. Furthermore, this species is the most economically important pollinator, whose health may be compromised by pesticide exposure, including oxidative stressors. Here, we develop a protocol for inducing oxidative stress in honey bee males (drones) via Paraquat injection. After injection, individuals from different colony sources were kept in common social conditions to monitor their survival compared to saline-injected controls. Oxidative stress was measured in susceptible and resistant individuals. Paraquat drastically reduced survival but individuals varied in their resistance to treatment within and among colony sources. Longer-lived individuals exhibited higher levels of lipid peroxidation than individuals dying early. In contrast, the level of protein carbonylation was not significantly different between the two groups. This first study of oxidative stress in male honey bees suggests that survival of an acute oxidative stressor is due to tolerance, not prevention or repair, of oxidative damage to lipids. It also demonstrates colony differences in oxidative stress resistance that might be useful for breeding stress-resistant honey bees.

  10. The protective effect of L-carnitine against hippocampal damage due to experimental formaldehyde intoxication in rats.

    PubMed

    Ozmen, E; Ozsoy, S Y; Donmez, N; Ozsoy, B; Yumuşak, N

    2014-07-01

    We investigated the protective effects of L-carnitine on hippocampus tissue damage in rats during experimental formaldehyde (FA) intoxication. Male Wistar albino rats were assigned into four groups: (1) control (C), (2) formaldehyde (FA), (3) formaldehyde + 0.5 g/kg of L-carnitine (FA + 0.5 LC) (4) formaldehyde + 1 g/kg L-carnitine (FA + 1 LC). At the end of the 14 day trial period, animals were sacrificed by decapitation under anesthesia. The hippocampus tissue samples were extracted to measure MDA, GSH and SOD activity. Neuronal degeneration was assessed based on histopathological (hematoxylin and eosin) and immunohistochemical (anti-ubiquitin) examination. To detect oxidative stress, specimens were reacted with anti-Cu/Zn-SOD antibody. After administering L-carnitine with FA to the animals, the activities of SOD and GSH increased, but the levels of MDA decreased in hippocampus tissue. Neuronal degeneration was observed in the FA group. L-carnitine administration reduced neuronal degeneration and histological structure was similar to controls. After FA application, degenerated hippocampus neurons were stained with anti-ubiquitin and Cu/Zn-SOD antibodies; weakly positive staining was observed in L- carnitine-treated groups. L-carnitine may be useful for preventing oxidative damage in the hippocampus tissue due to formaldehyde intoxication.

  11. Modelling biofilm-induced formation damage and biocide treatment in subsurface geosystems

    PubMed Central

    Ezeuko, C C; Sen, A; Gates, I D

    2013-01-01

    Biofilm growth in subsurface porous media, and its treatment with biocides (antimicrobial agents), involves a complex interaction of biogeochemical processes which provide non-trivial mathematical modelling challenges. Although there are literature reports of mathematical models to evaluate biofilm tolerance to biocides, none of these models have investigated biocide treatment of biofilms growing in interconnected porous media with flow. In this paper, we present a numerical investigation using a pore network model of biofilm growth, formation damage and biocide treatment. The model includes three phases (aqueous, adsorbed biofilm, and solid matrix), a single growth-limiting nutrient and a single biocide dissolved in the water. Biofilm is assumed to contain a single species of microbe, in which each cell can be a viable persister, a viable non-persister, or non-viable (dead). Persisters describe small subpopulation of cells which are tolerant to biocide treatment. Biofilm tolerance to biocide treatment is regulated by persister cells and includes ‘innate’ and ‘biocide-induced’ factors. Simulations demonstrate that biofilm tolerance to biocides can increase with biofilm maturity, and that biocide treatment alone does not reverse biofilm-induced formation damage. Also, a successful application of biological permeability conformance treatment involving geologic layers with flow communication is more complicated than simply engineering the attachment of biofilm-forming cells at desired sites. PMID:23164434

  12. Mutism and auditory agnosia due to bilateral insular damage--role of the insula in human communication.

    PubMed

    Habib, M; Daquin, G; Milandre, L; Royere, M L; Rey, M; Lanteri, A; Salamon, G; Khalil, R

    1995-03-01

    We report a case of transient mutism and persistent auditory agnosia due to two successive ischemic infarcts mainly involving the insular cortex on both hemispheres. During the 'mutic' period, which lasted about 1 month, the patient did not respond to any auditory stimuli and made no effort to communicate. On follow-up examinations, language competences had re-appeared almost intact, but a massive auditory agnosia for non-verbal sounds was observed. From close inspection of lesion site, as determined with brain resonance imaging, and from a study of auditory evoked potentials, it is concluded that bilateral insular damage was crucial to both expressive and receptive components of the syndrome. The role of the insula in verbal and non-verbal communication is discussed in the light of anatomical descriptions of the pattern of connectivity of the insular cortex.

  13. Late aneurysm formation of Valsalva sinus after aortic valve replacement due to Takayasu's arteritis.

    PubMed

    Funada, Akira; Kanzaki, Hideaki; Nagano, Nobutaka; Sugano, Yasuo; Ohara, Takahiro; Hasegawa, Takuya; Ishibashi-Ueda, Hatsue; Kitakaze, Masafumi; Anzai, Toshihisa

    2015-07-01

    Takayasu's arteritis (TA) is an inflammatory disease of unknown etiology involving the aorta and its branches, and also causes aortic regurgitation (AR). One of the most serious but rare complications after aortic valve replacement (AVR) in TA is aneurysm formation of the sinus of Valsalva. A 64-year-old woman had undergone AVR with a prosthetic valve for AR due to TA 4 years earlier and had received an implanted permanent pacemaker for complete atrioventricular block (AVB) 2 years later. Aortography 4 years postoperatively demonstrated aneurysm formation (47 mm in diameter) at the sinus of Valsalva although preoperative aortography showed severe AR without dilatation of the sinus of Valsalva. We recommended reoperation for the aneurysm but the patient refused. The perioperative histopathological examination revealed extensive destruction of the medial elastic fibers. Both the fragility of the sinus of Valsalva and the residual inflammation could have caused the patient's aneurysm formation. Moreover, extension of TA into the ventricular septum or mechanical compression of the aneurysm against the conduction system might have caused her progressive AVB. Close and lifelong follow-up for patients with TA regarding development of aneurysm after surgical treatment is indispensable when fragility of the aortic root had been confirmed.

  14. Formation of close binary black holes merging due to gravitational-wave radiation

    NASA Astrophysics Data System (ADS)

    Tutukov, A. V.; Cherepashchuk, A. M.

    2017-10-01

    The conditions for the formation of close-binary black-hole systems merging over the Hubble time due to gravitational-wave radiation are considered in the framework of current ideas about the evolution of massive close-binary systems. The original systems whose mergers were detected by LIGO consisted of main-sequence stars with masses of 30-100 M ⊙. The preservation of the compactness of a binary black hole during the evolution of its components requires either the formation of a common envelope, probably also with a low initial abundance of metals, or the presence of a "kick"—a velocity obtained during a supernova explosion accompanied by the formation of a black hole. In principle, such a kick can explain the relatively low frequency of mergers of the components of close-binary stellar black holes, if the characteristic speed of the kick exceeds the orbital velocities of the system components during the supernova explosion. Another opportunity for the components of close-binary systems to approach each other is related to their possible motion in a dense molecular cloud.

  15. Thermo-elasto-visco-plastic constitutive equations fully coupled with ductile damage. Application to metal cutting by chip formation

    NASA Astrophysics Data System (ADS)

    Lestriez, P.; Cherouat, A.; Saanouni, K.; Mariage, J. F.

    2004-06-01

    A fully coupled (strong coupling) thermo-elasto-visco-plastic-damage constitutive equations based on the state variables under large plastic deformation developed for metal forming simulation are presented. The relevant numerical aspects concerning either the local integration scheme as well as the global resolution strategy are discussed. This model is implemented into ABAQUS/EXPLICIT using the Vumat user subroutine. Applications are made to the orthogonal metal cutting by chip formation and segmentation. The interaction between hardening plasticity, ductile damage and thermal effects are carefully analyzed. The numerical results obtained with this procedure based on the damage coupling are compared with those obtained with the classical procedure neglecting the damage effect.

  16. Forecasting and modelling ice layer formation on the snowpack due to freezing precipitations in the Pyrenees

    NASA Astrophysics Data System (ADS)

    Quéno, Louis; Vionnet, Vincent; Cabot, Frédéric; Vrécourt, Dominique; Dombrowski-Etchevers, Ingrid

    2017-04-01

    In the Pyrenees, freezing precipitations in altitude occur at least once per winter, leading to the formation of a pure ice layer on the surface of the snowpack. It may lead to accidents and fatalities among mountaineers and skiers, with sometimes a higher human toll than avalanches. Such events are not predicted by the current operational systems for snow and avalanche hazard forecasting. A crowd-sourced database of surface ice layer occurrences is first built up, using reports from Internet mountaineering and ski-touring communities, to mitigate the lack of observations from conventional observation networks. A simple diagnostic of freezing precipitation is then developed, based on the cloud water content and screen temperature forecast by the Numerical Weather Prediction model AROME, operating at 2.5-km resolution. The performance of this diagnostic is assessed for the event of 5-6 January 2012, with a good representation of altitudinal and spatial distributions of the ice layer. An evaluation of the diagnostic for major events over five winters gives good skills of detection compared to the occurrences reported in the observation database. A new modelling of ice formation on the surface of the snowpack due to impinging supercooled water is added to the detailed snowpack model Crocus. It is combined to the atmospheric diagnostic of freezing precipitations and resulting snowpack simulations over a winter season capture well the formation of the main ice layers. Their influence on the snowpack stratigraphy is also realistically simulated. These simple methods enable to forecast the occurrence of surface ice layer formations with good confidence and to simulate their evolution within the snowpack, even if an accurate estimation of freezing precipitation amounts remains the main challenge.

  17. Inhomgeneous Dust Formation due to Turbulent Motion in Brown Dwarf Atmospheres

    NASA Astrophysics Data System (ADS)

    Helling, Ch.; Oevermann, M.; Lüttke, M.; Klein, R.; Sedlmayr, E.

    2001-05-01

    Brown Dwarfs are very faint, low mass star-like objects possibly bridging the gap between stars and planets. Their interior is dominated by convective energy transport which deposits energy, momentum, and matter into the atmosphere. Brown Dwarf atmospheres furthermore provide favorable conditions for the gas--solid phase transition due to their low temperatures and high densities since they are cool and compact objects. Brown Dwarfs are therefore an excellent test bed to study dust formation under turbulent conditions. In Brown Dwarfs, dust-free convective cells originating from the interior convective zone travel radially outward and decay into smaller and smaller eddies. Following Kolmogoroff's assumption, energy is transfered from the largest scales into smaller and smaller scales until the energy is finally dissipated on the Kolmogoroff scale (η ≈ 10-2cm for lref≈104cm) by the viscosity of the gas. Considering that the large scale turbulent motions have a characteristic Mach number M≈ 1, resulting acoustic waves create a turbulent temperature and density field in the atmosphere which influences the dust complex due to its high temperature and density sensitivity. Combining asymptotic techniques and time-dependent, multi-dimensional numerical simulations, we show that on microscopic scales acoustic waves can initiate dust nucleation in otherwise dust-hostile environments. An instable feedback loop occurs which is started by small temperature disturbances which allow the first dust particles to form. These particles grow to macroscopic sizes and thereby intensify the temperature decrease due to the radiative cooling which in turn re-initiates and henceforth intensifies dust formation. This runaway effect is stopped if all condensible material is consumed or the radiative equilibrium is reached.

  18. The hot-spot p53R172H mutant promotes formation of giant spermatogonia triggered by DNA damage.

    PubMed

    Xue, Y; Raharja, A; Sim, W; Wong, E S M; Rahmat, S A B; Lane, D P

    2017-04-06

    Overexpression of mutant p53 is a common finding in most cancers but testicular tumours accumulate wild-type p53 (wtp53). In contrast to the accepted concept that p53 homozygous mutant mice do not accumulate mutant p53 in normal cells, our study on a mutant p53 mouse model of Li-Fraumeni syndrome harbouring the hot-spot p53R172H mutation described an elevated level of mutant p53 in non-cancerous mouse tissues. Here we use detailed immunohistochemical analysis to document the expression of p53R172H in mouse testis. In developing and adult testes, p53R172H was expressed in gonocytes, type A, Int, B spermatogonia as well as in pre-Sertoli cells and Leydig cells but was undetectable in spermatocytes and spermatids. A similar staining pattern was demonstrated for wtp53. However, the intensity of wtp53 staining was generally weaker than that of p53R172H, which indicates that the expression of p53R172H can be a surrogate marker of p53 gene transcription. Comparing the responses of wtp53 and p53R172H to irradiation, we found persistent DNA double-strand breaks in p53R172H testes and the formation of giant spermatogonia (GSG) following persistent DNA damage in p53R172H and p53-null mice. Strikingly, we found that p53R172H promotes spontaneous formation of GSG in non-stressed p53R172H ageing mice. Two types of GSG: Viable and Degenerative GSG were defined. We elucidate the factors involved in the formation of GSG: the loss of p53 function is a requirement for the formation of GSG whereas DNA damage acts as a promoting trigger. The formation of GSG does not translate to higher efficacy of testicular tumorigenesis arising from mutant p53 cells, which might be due to the presence of delayed-onset of p53-independent apoptosis.

  19. Probabilistic analysis and fatigue damage assessment of offshore mooring system due to non-Gaussian bimodal tension processes

    NASA Astrophysics Data System (ADS)

    Chang, Anteng; Li, Huajun; Wang, Shuqing; Du, Junfeng

    2017-08-01

    Both wave-frequency (WF) and low-frequency (LF) components of mooring tension are in principle non-Gaussian due to nonlinearities in the dynamic system. This paper conducts a comprehensive investigation of applicable probability density functions (PDFs) of mooring tension amplitudes used to assess mooring-line fatigue damage via the spectral method. Short-term statistical characteristics of mooring-line tension responses are firstly investigated, in which the discrepancy arising from Gaussian approximation is revealed by comparing kurtosis and skewness coefficients. Several distribution functions based on present analytical spectral methods are selected to express the statistical distribution of the mooring-line tension amplitudes. Results indicate that the Gamma-type distribution and a linear combination of Dirlik and Tovo-Benasciutti formulas are suitable for separate WF and LF mooring tension components. A novel parametric method based on nonlinear transformations and stochastic optimization is then proposed to increase the effectiveness of mooring-line fatigue assessment due to non-Gaussian bimodal tension responses. Using time domain simulation as a benchmark, its accuracy is further validated using a numerical case study of a moored semi-submersible platform.

  20. The formation of bronchocutaneous fistulae due to retained epicardial pacing wires: A literature review

    PubMed Central

    Patris, Vasileios; Argiriou, Michalis; Salem, Agni-Leila; Giakoumidakis, Konstantinos; Baikoussis, Nikolaos G.; Charitos, Christos

    2016-01-01

    Temporary epicardial pacing wires during open-heart surgery are routinely used both for diagnostic and treatment purposes. In complicated cases where patients are unstable or the wires are difficult to remove, the pacing wires are cut at the skin level and allowed to retract by themselves. This procedure rarely causes complications. However, there have been cases reporting that retained pacing wires are linked to the formation of sterno-bronchial fistulae, which may present a while after the date of operation and are usually infected. This review aims to study the cases presenting sterno-bronchial fistulae due to retained epicardial pacing wires and to highlight the important factors associated with these. It is important to note these complications, as fistulae may cause a variety of problems to the patient if undiagnosed and left untreated. With the aid of scans such as fistulography, fistulae can be identified and treated and will improve the patients’ health dramatically. PMID:27716700

  1. Honey Bee (Apis mellifera) Drones Survive Oxidative Stress due to Increased Tolerance instead of Avoidance or Repair of Oxidative Damage

    PubMed Central

    Li-Byarlay, Hongmei; Huang, Ming Hua; Simone-Finstrom, Michael; Strand, Micheline K.; Tarpy, David R.; Rueppell, Olav

    2016-01-01

    Oxidative stress can lead to premature aging symptoms and cause acute mortality at higher doses in a range of organisms. Oxidative stress resistance and longevity are mechanistically and phenotypically linked; considerable variation in oxidative stress resistance exists among and within species and typically covaries with life expectancy. However, it is unclear whether stress-resistant, long-lived individuals avoid, repair, or tolerate molecular damage to survive longer than others. The honey bee (Apis mellifera L.) is an emerging model system that is well-suited to address this question. Furthermore, this species is the most economically important pollinator, whose health may be compromised by pesticide exposure, including oxidative stressors. Here, we develop a protocol for inducing oxidative stress in honey bee males (drones) via Paraquat injection. After injection, individuals from different colony sources were kept in common social conditions to monitor their survival compared to saline-injected controls. Oxidative stress was measured in susceptible and resistant individuals. Paraquat drastically reduced survival but individuals varied in their resistance to treatment within and among colony sources. Longer-lived individuals exhibited higher levels of lipid peroxidation than individuals dying early. In contrast, the level of protein carbonylation was not significantly different between the two groups. This first study of oxidative stress in male honey bees suggests that survival of an acute oxidative stressor is due to tolerance, not prevention or repair, of oxidative damage to lipids. It also demonstrates colony differences in oxidative stress resistance that might be useful for breeding stress-resistant honey bees. PMID:27422326

  2. Stratospheric denitrification due to polar aerosol formation: Implications for a future atmosphere with increased CO2

    NASA Astrophysics Data System (ADS)

    Pitari, Giovanni; Ricciardulli, Lucrezia

    The amount of stratospheric denitrification produced by NAT aerosol formation is studied with a photochemical two-dimensional model which includes the effects of zonal asymmetries of the temperature field. The model photochemistry is coupled with a microphysical code for aerosol formation and growth, so that the permanent loss of stratospheric nitric acid and water vapor may be taken into account. The model results for nitric acid relative to the atmospheric chemical composition of 1980 are compared with LIMS data. We show that the level of denitrification may rise substantially if the polar vortex cools down, as it could be the case in a future atmosphere richer in carbon dioxide. A three-dimensional model is used to calculate the temperature perturbation due to an increase of CO2 from 335 ppmv of 1980 (baseline) up to 500 ppmv (predicted for 2050). The photochemical model adopting these new temperatures predicts an average 20% HNO3 column decrease poleward of 45N with respect to baseline. One consequence is that the relative weight of the NOx catalytic cycle for O3 destruction decreases with respect to the present atmosphere.

  3. Conduction Channel Formation and Dissolution Due to Oxygen Thermophoresis/Diffusion in Hafnium Oxide Memristors

    SciTech Connect

    Kumar, Suhas; Wang, Ziwen; Huang, Xiaopeng; Kumari, Niru; Davila, Noraica; Strachan, John Paul; Vine, David; Kilcoyne, A. L. David; Nishi, Yoshio; Williams, R. Stanley

    2016-12-27

    Due to the favorable operating power, endurance, speed, and density., transition-metal-oxide memristors, or resistive random-access memory (RRAM) switches, are under intense development for storage-class memory. Their commercial deployment critically depends on predictive compact models based on understanding nanoscale physiocochemical forces, which remains elusive and controversial owing to the difficulties in directly observing atomic motions during resistive switching, Here, using scanning transmission synchrotron X-ray spectromicroscopy to study in situ switching of hafnium oxide memristors, we directly observed the formation of a localized oxygen-deficiency-derived conductive channel surrounded by a low-conductivity ring of excess oxygen. Subsequent thermal annealing homogenized the segregated oxygen, resetting the cells toward their as-grown resistance state. We show that the formation and dissolution of the conduction channel are successfully modeled by radial thermophoresis and Fick diffusion of oxygen atoms driven by Joule heating. This confirmation and quantification of two opposing nanoscale radial forces that affect bipolar memristor switching are important components for any future physics-based compact model for the electronic switching of these devices.

  4. Activation of DNA damage response pathways as a consequence of anthracycline-DNA adduct formation.

    PubMed

    Forrest, Robert A; Swift, Lonnie P; Rephaeli, Ada; Nudelman, Abraham; Kimura, Ken-Ichi; Phillips, Don R; Cutts, Suzanne M

    2012-06-15

    The cytotoxicity of doxorubicin, a clinically used anti-neoplastic drug, can be enhanced by formaldehyde (either endogenous or exogenous) to promote the formation of doxorubicin-DNA adducts. Formaldehyde supplies the carbon required for the covalent linkage of doxorubicin to one strand of DNA, with hydrogen bonds stabilising the doxorubicin mono-adduct to the other strand of DNA, to act much like an interstrand crosslink. Interstrand crosslinks present a major challenge for cellular repair processes, requiring the activation of numerous DNA damage response proteins for resolution of the resulting DNA intermediates and damage. This work investigates DNA damage response proteins activated by doxorubicin-DNA adducts. Although p53 was phosphorylated at Serine 15 in response to adducts, long term growth inhibition of mammalian cells was not affected by p53 status. Using siRNA technology and kinase inhibitors we observed enhanced cellular sensitivity to doxorubicin-DNA adducts when the activity of the signalling protein kinases ATM and ATR were lost. Cells synchronised using a double thymidine block were sensitised to adduct-initiated cell death upon ATR knockdown, but relatively unaffected by ATM knockdown. Loss of ATR was associated with abrogation of a drug-induced G(2)/M block and induction of mitotic catastrophe, while loss of ATM was associated with drug-induced apoptosis in non-synchronised cells. These proteins may therefore be potential drug targets to achieve synergistic cytotoxic responses to doxorubicin-DNA adduct forming therapies. The analysis of these protein kinases with respect to cell cycle progression indicates that ATR is required for G(2)/M checkpoint responses while ATM appears to function in G(1) mediated responses to anthracycline adducts. Copyright © 2012 Elsevier Inc. All rights reserved.

  5. Chronic heat treatment causes skin wrinkle formation and oxidative damage in hairless mice.

    PubMed

    Shin, Mi Hee; Seo, Jo-Eun; Kim, Yeon Kyung; Kim, Kyu Han; Chung, Jin Ho

    2012-01-01

    We have previously demonstrated that heat shock could induce expression of matrix metalloproteinases (MMPs) in skin cells. These results implicated that chronic heat treatment may cause skin wrinkles. Therefore, in the present study, we investigated the effects of chronic heat treatment (43 °C, 30 min, 3 times/week, 6 weeks) on wrinkle formation in skin of hairless mice. We found that repetitive heat treatment induced skin wrinkles after a period of 6 weeks in skin of hairless mice. Histologically, heat treatment resulted in increased thickness of the epidermis and dermis. And repetitive heat treatment resulted in significantly increased expression of MMP-13 protein and mRNA, but not MMP-2 and -9, in skin of hairless mice. We also demonstrated that activities of antioxidant enzymes, catalase, and superoxide dismutase (SOD), were reduced by chronic heat treatment. In addition, oxidative damage was increased in skin of mice after chronic exposure to heat shock. Taken together, our results suggested that chronic exposure of the skin to heat can cause skin wrinkling. And, increase of MMP-13, decrease of antioxidant enzymes activity, and consequent oxidative damage by chronic heat treatment may play an important role in development of skin aging in hairless mice. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  6. Decrease in corneal damage due to benzalkonium chloride by the addition of sericin into timolol maleate eye drops.

    PubMed

    Nagai, Noriaki; Ito, Yoshimasa; Okamoto, Norio; Shimomura, Yoshikazu

    2013-01-01

    We investigated the protective effects of sericin on corneal damage due to benzalkonium chloride (BAC) used as a preservative in commercially available timolol maleate eye drops using rat debrided corneal epithelium and a human cornea epithelial cell line (HCE-T). Corneal wounds were monitored using a fundus camera TRC-50X equipped with a digital camera; eye drops were instilled into the rat eyes five times a day after corneal epithelial abrasion. The viability of HCE-T cells was calculated by TetraColor One; and Escherichia coli (ATCC 8739) were used to measure antimicrobial activity. The reducing effects on transcorneal penetration and intraocular pressure (IOP) of the eye drops were determined using rabbits. The corneal wound healing rate and rate constants (kH) as well as cell viability were higher following treatment with 0.005% BAC solution containing 0.1% sericin than in the case of treatment with BAC solution alone; the antimicrobial activity was approximately the same for BAC solutions with and without sericin. In addition, the kH for rat eyes instilled with commercially available timolol maleate eye drops containing 0.1% sericin was significantly higher than that of eyes instilled with timolol maleate eye drops without sericin, and the addition of sericin did not affect the corneal penetration or IOP reducing effect of commercially available timolol maleate eye drops. A preservative system comprising BAC and sericin may provide effective therapy for glaucoma patients requiring long-term anti-glaucoma agents.

  7. Acute glutaraldehyde mucosal injury of the upper aerodigestive tract due to damage to the working channel of an endoscope.

    PubMed

    Krishna, Priya D; Statham, Melissa McCarty; Rosen, Clark A

    2010-03-01

    Glutaraldehyde (Cidex) is a commonly used agent for cold sterilization of endoscopes despite its known irritative, allergic, and carcinogenic potential. This report details the clinical course of 2 patients who suffered acute glutaraldehyde exposure during office injection procedures. Clinical records of 2 outpatients undergoing office injection procedures were reviewed. One patient underwent bilateral injections of hydroxyapatite, and 1 underwent voice gel injection. Both patients developed acute mucosal injury in the form of supraglottitis and laryngitis. Both patients required inpatient admission with airway monitoring (1 requiring admission to the intensive care unit) and were treated with steroids and antibiotics. The same channel endoscope was used for both procedures and was noted after careful examination to have retained glutaraldehyde inside the scope due to a perforation of the lining of the working channel. Glutaraldehyde can cause acute mucosal injury to supraglottic and glottic structures, and diligent procedures must be maintained for flushing the channels and monitoring glutaraldehyde retention in the channels. Great care should be taken to avoid damage to the lining of working channels from instrumentation.

  8. Mono and sequential ion irradiation induced damage formation and damage recovery in oxide glasses: Stopping power dependence of the mechanical properties

    NASA Astrophysics Data System (ADS)

    Mir, A. H.; Monnet, I.; Toulemonde, M.; Bouffard, S.; Jegou, C.; Peuget, S.

    2016-02-01

    Simple and complex borosilicate glasses were irradiated with single and double ion beams of light and heavy ions over a broad fluence and stopping power range. As a result of the heavy ion irradiation (U, Kr, Au), the hardness was observed to diminish and saturate after a decrease by 35 ± 1%. Unlike slow and swift heavy ion irradiation, irradiation with light ions (He,O) induced a saturation hardness decrease of 18 ± 1% only. During double ion beam irradiation; where glasses were first irradiated with a heavy ion (gold) and then by a light ion (helium), the light ion irradiation induced partial damage recovery. As a consequence of the recovery effect, the hardness of the pre-irradiated glasses increased by 10-15% depending on the chemical composition. These results highlight that the nuclear energy loss and high electronic energy loss (≥4 keV/nm) result in significant and similar modifications whereas light ions with low electronic energy loss (≤1 keV/nm) result in only mild damage formation in virgin glasses and recovery in highly pre-damaged glasses. These results are important to understand the damage formation and recovery in actinide bearing minerals and in glasses subjected to self-irradiation by alpha decays.

  9. Type VII collagen deficiency causes defective tooth enamel formation due to poor differentiation of ameloblasts.

    PubMed

    Umemoto, Hiroko; Akiyama, Masashi; Domon, Takanori; Nomura, Toshifumi; Shinkuma, Satoru; Ito, Kei; Asaka, Takuya; Sawamura, Daisuke; Uitto, Jouni; Uo, Motohiro; Kitagawa, Yoshimasa; Shimizu, Hiroshi

    2012-11-01

    Recessive dystrophic epidermolysis bullosa (RDEB) is caused by mutations in the gene encoding type VII collagen (COL7), a major component of anchoring fibrils in the epidermal basement membrane zone. Patients with RDEB present a low oral hygiene index and prevalent tooth abnormalities with caries. We examined the tooth enamel structure of an RDEB patient by scanning electron microscopy. It showed irregular enamel prisms, indicating structural enamel defects. To elucidate the pathomechanisms of enamel defects due to COL7 deficiency, we investigated tooth formation in Col7a1(-/-) and COL7-rescued humanized mice that we have established. The enamel from Col7a1(-/-) mice had normal surface structure. The enamel calcification and chemical composition of Col7a1(-/-) mice were similar to those of the wild type. However, transverse sections of teeth from the Col7a1(-/-) mice showed irregular enamel prisms, which were also observed in the RDEB patient. Furthermore, the Col7a1(-/-) mice teeth had poorly differentiated ameloblasts, lacking normal enamel protein-secreting Tomes' processes, and showed reduced mRNA expression of amelogenin and other enamel-related molecules. These enamel abnormalities were corrected in the COL7-rescued humanized mice expressing a human COL7A1 transgene. These findings suggest that COL7 regulates ameloblast differentiation and is essential for the formation of Tomes' processes. Collectively, COL7 deficiency is thought to disrupt epithelial-mesenchymal interactions, leading to defective ameloblast differentiation and enamel malformation in RDEB patients. Copyright © 2012 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  10. Formation of Cyclic Steps due to the Surge-type Turbidity Currents in a Flume Experiment

    NASA Astrophysics Data System (ADS)

    Yokokawa, M.

    2016-12-01

    Supercritical turbidity currents often form crescentic step-like wavy structures, which have been found at the submarine canyons, and deltaic environments. Field observations of turbidity currents and seabed topography on the Squamish delta in British Columbia, Canada revealed that cyclic steps formed by the surge-type turbidity currents (e.g., Hughes Clarke et al., 2012a; 2012b; 2014). The high-density portion of the flow, which affects the sea floor morphology, lasted only 30-60 seconds. The questions arise if we can reconstruct paleo-flow condition from the morphologic features of these steps. We don't know answers right now because there have been no experiments about the formative conditions of cyclic steps due to the "surge-type" turbidity currents. Here we did preliminary experiments on the formation of cyclic steps due to the multiple surge-type density currents, and compare the morphology of the steps with those of Squamish delta. First of all, we measured wave length and wave height of each step from profiles of each channels of Squamish delta from the elevation data and calculated the wave steepness. Wave steepness of active steps ranges about 0.05 to 0.15, which is relatively larger compare with those of other sediment waves. And in general, wave steepness is larger in the proximal region. The experiments had been performed at Osaka Institute of Technology. A flume, which is 7.0 m long, 0.3 m deep and 2 cm wide, was suspended in a larger tank, which is 7.6 m long, 1.2 m deep and 0.3 m wide, filled with water. The inner flume tilted at 7 degrees. Mixture of salt water (1.17 g/cm3) and plastic particles (1.5 g/cm3, 0.1-0.18 mm in diameter), whose weight ratio is 10:1, poured into the upstream end of the inner flume from head tank for 5 seconds. Discharge of the mixture was 240mL/s, thus for 5seconds 1200mL of mixture was released into the inner flume. We made 130 surges. As a result, four steps were formed ultimately, which were moving toward upstream

  11. Spontaneous Formation of Eutectic Crystal Structures in Binary and Ternary Charged Colloids due to Depletion Attraction

    NASA Astrophysics Data System (ADS)

    Toyotama, Akiko; Okuzono, Tohru; Yamanaka, Junpei

    2016-03-01

    Crystallization of colloids has extensively been studied for past few decades as models to study phase transition in general. Recently, complex crystal structures in multi-component colloids, including alloy and eutectic structures, have attracted considerable attention. However, the fabrication of 2D area-filling colloidal eutectics has not been reported till date. Here, we report formation of eutectic structures in binary and ternary aqueous colloids due to depletion attraction. We used charged particles + linear polyelectrolyte systems, in which the interparticle interaction could be represented as a sum of the electrostatic, depletion, and van der Waals forces. The interaction was tunable at a lengthscale accessible to direct observation by optical microscopy. The eutectic structures were formed because of interplay of crystallization of constituent components and accompanying fractionation. An observed binary phase diagram, defined by a mixing ratio and inverse area fraction of the particles, was analogous to that for atomic and molecular eutectic systems. This new method also allows the adjustment of both the number and wavelengths of Bragg diffraction peaks. Furthermore, these eutectic structures could be immobilized in polymer gel to produce self-standing materials. The present findings will be useful in the design of the optical properties of colloidal crystals.

  12. Spontaneous Formation of Eutectic Crystal Structures in Binary and Ternary Charged Colloids due to Depletion Attraction

    PubMed Central

    Toyotama, Akiko; Okuzono, Tohru; Yamanaka, Junpei

    2016-01-01

    Crystallization of colloids has extensively been studied for past few decades as models to study phase transition in general. Recently, complex crystal structures in multi-component colloids, including alloy and eutectic structures, have attracted considerable attention. However, the fabrication of 2D area-filling colloidal eutectics has not been reported till date. Here, we report formation of eutectic structures in binary and ternary aqueous colloids due to depletion attraction. We used charged particles + linear polyelectrolyte systems, in which the interparticle interaction could be represented as a sum of the electrostatic, depletion, and van der Waals forces. The interaction was tunable at a lengthscale accessible to direct observation by optical microscopy. The eutectic structures were formed because of interplay of crystallization of constituent components and accompanying fractionation. An observed binary phase diagram, defined by a mixing ratio and inverse area fraction of the particles, was analogous to that for atomic and molecular eutectic systems. This new method also allows the adjustment of both the number and wavelengths of Bragg diffraction peaks. Furthermore, these eutectic structures could be immobilized in polymer gel to produce self-standing materials. The present findings will be useful in the design of the optical properties of colloidal crystals. PMID:26984298

  13. Spontaneous Formation of Eutectic Crystal Structures in Binary and Ternary Charged Colloids due to Depletion Attraction.

    PubMed

    Toyotama, Akiko; Okuzono, Tohru; Yamanaka, Junpei

    2016-03-17

    Crystallization of colloids has extensively been studied for past few decades as models to study phase transition in general. Recently, complex crystal structures in multi-component colloids, including alloy and eutectic structures, have attracted considerable attention. However, the fabrication of 2D area-filling colloidal eutectics has not been reported till date. Here, we report formation of eutectic structures in binary and ternary aqueous colloids due to depletion attraction. We used charged particles + linear polyelectrolyte systems, in which the interparticle interaction could be represented as a sum of the electrostatic, depletion, and van der Waals forces. The interaction was tunable at a lengthscale accessible to direct observation by optical microscopy. The eutectic structures were formed because of interplay of crystallization of constituent components and accompanying fractionation. An observed binary phase diagram, defined by a mixing ratio and inverse area fraction of the particles, was analogous to that for atomic and molecular eutectic systems. This new method also allows the adjustment of both the number and wavelengths of Bragg diffraction peaks. Furthermore, these eutectic structures could be immobilized in polymer gel to produce self-standing materials. The present findings will be useful in the design of the optical properties of colloidal crystals.

  14. Siderophile Element Depletion in the Angrite Parent Body (APB) Mantle: Due to Core Formation?

    NASA Technical Reports Server (NTRS)

    Righter, K.

    2008-01-01

    The origin of angrites has evaded scientists due in part to unusual mineralogy, oxidized character, and small numbers of samples. Increased interest in the origin of angrites has stemmed from the recovery of approximately 10 new angrites in the past decade. These new samples have allowed meteoriticists to recognize that angrites are compositionally diverse, old, and record very early differentiation. Also, a magma ocean has been proposed to have been involved in APB early differentiation, but this remains untested for siderophile elements which are commonly cited as one of the main lines of evidence for magma oceans on the early Earth, Moon, Mars and eucrite parent body (e.g., [6]). And recent suggestions that angrites may or may not be from Mercury have also peaked interest in these achondrites. Given all of this background, a detailed understanding of the early differentiation process is desired. Previous efforts at examining siderophile element (SE) concentrations with respect to core formation processes in the APB have not resulted in any definite conclusions regarding segregation of a metallic core. The goal of this study is to summarize what is known about SE concentrations in the suite, estimate depletions of SE compared to chondrites, and apply metal/silicate experimental partition coefficients to assess whether the APB had a core.

  15. Formation of mixed layers and compounds on beryllium due to C + and CO + bombardment

    NASA Astrophysics Data System (ADS)

    Goldstrass, P.; Linsmeier, Ch.

    2001-03-01

    Compound formation on a clean beryllium single crystal (0 0 0 1) during bombardment with 5 keV C + and 3 and 5 keV CO + ions is studied by means of in situ X-ray photoelectron spectroscopy (XPS). In combination with in situ Rutherford backscattering analysis (RBS), TRIDYN computer simulation, and measurements of the weight change of the sample due to the bombardment, models for the sample composition changes and erosion mechanisms are derived for both ion species. In the case of C + bombardment a carbon layer builds up on top of the beryllium. The transition region from pure beryllium to pure carbon consists partly of Be 2C and the beryllium erosion stops as the covering carbon layer develops. During CO + bombardment a deposition/erosion equilibrium is established. After initial C and O accumulation, the beryllium substrate is covered by a ternary mixture layer of about 10 nm thickness containing BeO, elementary carbon and C-O compounds. Be 2C is present only at low fluences and before the equilibrium is established. The erosion of beryllium proceeds and a chemical erosion process limits the deposited amounts of carbon and oxygen via emission of CO.

  16. Irreversible fouling of membrane bioreactors due to formation of a non-biofilm gel layer.

    PubMed

    Poorasgari, E; Larsen, P; Zheng, X; Nielsen, P H; Keiding, K; Christensen, M L

    2014-01-01

    Extra-cellular polymeric substances (EPS), known to contribute to fouling in membrane bio-reactors (MBRs), are generally divided into bound and free EPS. The free EPS are able to form a gel layer on the membrane active surface. The mechanisms involved in formation of such layer and its effects on performance of the MBR membranes were studied. The free EPS, extracted by centrifugation and microfiltration, contained a significant amount of humic-like substances. Under static contact to the membrane, adsorption of humic-like substances to the membrane occurred and could be explained by conventional adsorption kinetics. Due to static adsorption, surface roughness of the membrane declined significantly, indicating that adsorbed matters to the membrane filled the cavities of the membrane surface. Filtration of the free EPS caused 50% water flux decline. The fouling resistance linearly increased with the amount of the humic-like substances retained during filtration as predicted by gel growth theory. A low pressure backwash could re-establish the water flux only up to 70%.

  17. Damage Zones and Microcrack Formation Associated with Laboratory Produced Extension Fractures

    NASA Astrophysics Data System (ADS)

    Bradley, E. E.; Boutt, D. F.; Goodwin, L. B.

    2011-12-01

    Both joint sets and fault-related fractures serve as important conduits for fluid flow. In the former case, they can strongly influence both permeability and permeability anisotropy, with implications for production of water, hydrocarbons and contaminant transport. The latter can affect issues of fluid flow, such as whether a given fault seals or leaks, as well as fault mechanics. These fractures are commonly interpreted as Natural Hydraulic Fractures (NHFs), i.e., fractures produced when pore fluid pressure exceeds the tensile strength of the rock. Various mathematical models have been a rich source of hypotheses to explain the formation and propagation of these fractures, but have provided only limited information about fracture spacing and nothing about processes of fracture initiation in originally intact rock. Recent laboratory experiments of French (2009) have advanced our understanding of mechanical controls on fracture initiation and spacing. Here, detailed analysis of both through-going fracture surfaces and microcrack distributions in experimentally deformed samples provide a deeper understanding of NHF processes and resulting geometric features in porous siliciclastic sedimentary rocks. We studied fractures in a homogeneous, isotropic, fine to medium-grained quartz arenite, a homogeneous, anisotropic, coarse-grained quartz-rich siltstone, and a heterogeneous, isotropic, medium-grained quartz arenite. Both homogeneous samples developed a single, through-going fracture surrounded by a halo, or damage zone, of microcracks during the experiment. The fracture in the homogenous isotropic sample formed in the center of the sample where the pore fluid pressure was highest. It is the most planar fracture in the three samples, and has a microcrack damage zone that is symmetrical and extends nearly 2 cm to either side of the fracture. The homogeneous anisotropic sample's fracture formed away from the location of maximum pore fluid pressure, and was apparently

  18. Clusters of DNA damage induced by ionizing radiation: formation of short DNA fragments. II. Experimental detection

    NASA Technical Reports Server (NTRS)

    Rydberg, B.; Chatterjee, A. (Principal Investigator)

    1996-01-01

    The basic 30-nm chromatin fiber in the mammalian cell consists of an unknown (possibly helical) arrangement of nucleosomes, with about 1.2 kb of DNA per 10-nm length of fiber. Track-structure considerations suggest that interactions of single delta rays or high-LET particles with the chromatin fiber might result in the formation of multiple lesions spread over a few kilobases of DNA (see the accompanying paper: W.R. Holley and A. Chatterjee, Radiat. Res. 145, 188-199, 1996). In particular, multiple DNA double-strand breaks and single-strand breaks may form. To test this experimentally, primary human fibroblasts were labeled with [3H]thymidine and exposed at 0 degrees C to X rays or accelerated nitrogen or iron ions in the LET range of 97-440 keV/microns. DNA was isolated inside agarose plugs and subjected to agarose gel electrophoresis under conditions that allowed good separation of 0.1-2 kb size DNA. The bulk of DNA remained in the well or migrated only a small distance into the gel. It was found that DNA fragments in the expected size range were formed linearly with dose with an efficiency that increased with LET. A comparison of the yield of such fragments with the yield of total DNA double-strand breaks suggests that for the high-LET ions a substantial proportion (20-90%) of DNA double-strand breaks are accompanied within 0.1-2 kb by at least one additional DNA double-strand break. It is shown that these results are in good agreement with theoretical calculations based on treating the 30-nm chromatin fiber as the target for ionizing particles. Theoretical considerations also predict that the clusters will contain numerous single-strand breaks and base damages. It is proposed that such clusters be designated "regionally multiply damaged sites." Postirradiation incubation at 37 degrees C resulted in a decline in the number of short DNA fragments, suggesting a repair activity. The biological significance of regionally multiply damaged sites is presently unknown.

  19. Clusters of DNA damage induced by ionizing radiation: formation of short DNA fragments. II. Experimental detection

    NASA Technical Reports Server (NTRS)

    Rydberg, B.; Chatterjee, A. (Principal Investigator)

    1996-01-01

    The basic 30-nm chromatin fiber in the mammalian cell consists of an unknown (possibly helical) arrangement of nucleosomes, with about 1.2 kb of DNA per 10-nm length of fiber. Track-structure considerations suggest that interactions of single delta rays or high-LET particles with the chromatin fiber might result in the formation of multiple lesions spread over a few kilobases of DNA (see the accompanying paper: W.R. Holley and A. Chatterjee, Radiat. Res. 145, 188-199, 1996). In particular, multiple DNA double-strand breaks and single-strand breaks may form. To test this experimentally, primary human fibroblasts were labeled with [3H]thymidine and exposed at 0 degrees C to X rays or accelerated nitrogen or iron ions in the LET range of 97-440 keV/microns. DNA was isolated inside agarose plugs and subjected to agarose gel electrophoresis under conditions that allowed good separation of 0.1-2 kb size DNA. The bulk of DNA remained in the well or migrated only a small distance into the gel. It was found that DNA fragments in the expected size range were formed linearly with dose with an efficiency that increased with LET. A comparison of the yield of such fragments with the yield of total DNA double-strand breaks suggests that for the high-LET ions a substantial proportion (20-90%) of DNA double-strand breaks are accompanied within 0.1-2 kb by at least one additional DNA double-strand break. It is shown that these results are in good agreement with theoretical calculations based on treating the 30-nm chromatin fiber as the target for ionizing particles. Theoretical considerations also predict that the clusters will contain numerous single-strand breaks and base damages. It is proposed that such clusters be designated "regionally multiply damaged sites." Postirradiation incubation at 37 degrees C resulted in a decline in the number of short DNA fragments, suggesting a repair activity. The biological significance of regionally multiply damaged sites is presently unknown.

  20. Clusters of DNA damage induced by ionizing radiation: Formation of short DNA fragments. II. Experimental detection

    SciTech Connect

    Rydberg, B.

    1996-02-01

    The basic 30-nm chromatin fiber in the mammalian cell consists of an unknown (possibly helical) arrangement of nucleosomes, with about 1.2 kb of DNA per 10-nm length of fiber. Track-structure considerations suggest that interactions of single {delta} rays or high-LET particles with the chromatin fiber might result in the formation of multiple lesions spread over a few kilobases of DNA. In particular, multiple DNA double-strand breaks and single-strand breaks may form. To test this experimentally, primary human fibroblasts were labeled with [{sup 3}H]thymidine and exposed at 0{degrees}C to X rays or accelerated nitrogen or iron ions in the LET range of 97-440 keV/pm. DNA was isolated inside agarose plugs and subjected to agarose gel electrophoresis under conditions that allowed good separation of 0.1-2 kb size DNA. The bulk of DNA remained in the well or migrated only a small distance into the gel. It was found that DNA fragments in the expected size range were formed linearly with dose with an efficiency that increased with LET. A comparison of the yield of such fragments with the yield of total DNA double-strand breaks suggests that for the high-LET ions a substantial proportion (20-90%) of DNA double-strand breaks are accompanied within 0.1-2 kb by at least one additional DNA double-strand break. It is shown that these results are in good agreement with theoretical calculations based on treating the 30-nm chromatin fiber as the target for ionizing particles. Theoretical considerations also predict that the clusters will contain numerous single-strand breaks and base damages. It is proposed that such clusters be designated {open_quotes}regionally multiply damaged sites.{close_quotes} Postirradiation incubation at 37{degrees}C resulted in a decline in the number of short DNA fragments, suggesting a repair activity. The biological significance of regionally multiply damaged sites is presently unknown. 34 refs., 6 figs., 1 tab.

  1. Dysbaric osteonecrosis: a consequence of intravascular bubble formation, endothelial damage, and platelet thrombosis.

    PubMed

    Slichter, S J; Stegall, P; Smith, K; Huang, T W; Harker, L A

    1981-10-01

    formation. Since the diving characteristics of increasing depth and inadequate decompression were associated with both the most severe consumption and the highest frequency of intravascular bubble formation, we postulate that intravascular bubbles, formed during hyperbaria, produce osteonecrosis, perhaps through the following sequence: (1) bubble-related endothelial cell damage; (2) platelet thrombus formation with secondary fibrin deposition; (3) microvascular occlusion; and (4) platelet-dependent arterial narrowing through intimal lesion formation. The role of antithrombotic therapy in the prevention of dysbaric osteonecrosis remains to be determined.

  2. In field damage of high and low cyanogenic cassava due to a generalist insect herbivore Cyrtomenus bergi (Hemiptera: Cydnidae).

    PubMed

    Riis, Lisbeth; Bellotti, Anthony Charles; Castaño, Oscar

    2003-12-01

    The hypothesis that cyanogenic potential in cassava roots deters polyphagous insects in the field is relevant to current efforts to reduce or eliminate the cyanogenic potential in cassava. To test this hypothesis, experiments were conducted in the field under natural selection pressure of the polyphagous root feeder Cyrtomenus bergi Froeschner (Hemiptera: Cydnidae). A number of cassava varieties (33) as well as 13 cassava siblings and their parental clone, each representing a determined level of cyanogenic potential (CNP), were scored for damage caused by C. bergi and related to CNP and nonglycosidic cyanogens, measured as hydrogen cyanide. Additionally, 161 low-CNP varieties (< 50 ppm hydrogen cyanide, fresh weight) from the cassava germplasm core collection at Centro Internacional de Agricultura Tropical (CIAT) were screened for resistance/tolerance to C. bergi. Low root damage scores were registered at all levels of CNP. Nevertheless, CNP and yield (or root size) partly explained the damage in cassava siblings (r2 = 0.82) and different cassava varieties (r2 = 0.42), but only when mean values of damage scores were used. This relation was only significant in one of two crop cycles. A logistic model describes the underlying negative relation between CNP and damage. An exponential model describes the underlying negative relation between root size and damage. Damage, caused by C. bergi feeding, released nonglycosidic cyanogens, and an exponential model fits the underlying positive relation. Fifteen low-CNP clones were selected for potential resistance/tolerance against C. bergi.

  3. Development of advanced drilling, completion, and stimulation systems for minimum formation damage and improved efficiency: A program overview

    SciTech Connect

    Layne, A.W.; Yost, A.B. II

    1994-07-01

    The Department of Energy`s (DOE) Natural Gas Resource and Extraction Program consists of industry/government co-sponsored research, development, and demonstration (RD&D) projects, which focus on gas recovery from both conventional and nonconventional resources. The Drilling, Completion, and Stimulation (DCS) Project focuses on advanced, non-damaging technology systems and equipment for improving gas recovery from conventional and nonconventional reservoirs. As operators move from development of current day economically attractive gas-field development to the lower permeability geologic regions of domestic onshore plays, increasing the emphasis on minimum formation damage DCS will permit economic development of gas reserves. The objective of the Project is to develop and demonstrate cost-effective, advanced technology to accelerate widespread use and acceptance of minimum formation damage DCS systems. The goal of this product development effort is to reduce costs and improve the overall efficiency of vertical, directional, and horizontally drilled wells in gas formations throughout the US. The current focus of the Project is on the development of underbalanced drilling technology and minimum formation damage stimulation technology concurrently with the appropriate completion hardware to improve the economics of domestic natural gas field development. Ongoing drilling technology projects to be discussed include development of an electromagnetic measurement while drilling system for directional and horizontal drilling in underbalanced drilling applications and the development of a steerable air percussion drilling system for hard formation drilling and improved penetration rates. Ongoing stimulation technology projects to be discussed include introduction of carbon dioxide/sand fracturing technology for minimal formation damage.

  4. TRANSGENIC OVEREXPRESSION OF NEUROGLOBIN ATTENUATES FORMATION OF SMOKE INHALATION-INDUCED OXIDATIVE DNA DAMAGE, IN VIVO, IN THE MOUSE BRAIN

    PubMed Central

    Lee, Heung Man; Greeley, George H.; Englander, Ella W.

    2011-01-01

    Acute inhalation of combustion smoke causes neurological deficits in survivors. Inhaled smoke includes carbon monoxide, noxious gases and hypoxic environment, which disrupt oxygenation and generate free radicals. To replicate a smoke inhalation scenario, we developed experimental model of acute exposure to smoke for the awake mouse/rat and detected induction of biomarkers of oxidative stress. These include inhibition of mitochondrial respiratory complexes and formation of oxidative DNA damage in the brain. DNA damage is likely to contribute to neuronal dysfunction and progression of brain injury. In search for strategies to attenuate the smoke initiated brain injury, we produced a transgenic mouse overexpressing the neuronal globin protein, neuroglobin. Neuroglobin was found neuroprotective in diverse models of ischemic/hypoxic/toxic brain injuries. Here, we report lesser inhibition of respiratory complex I and reduced formation of smoke-induced DNA damage in neuroglobin transgene when compared to the wild-type mouse brain. DNA damage was assessed using the standard comet assay, as well as a modified comet assay done in conjunction with an enzyme, which excises oxidized guanines that form readily under conditions of oxidative stress. Both comet assays revealed that overexpressed neuroglobin attenuates the formation of oxidative DNA damage, in vivo, in the brain. These findings suggest that elevated neuroglobin exerts neuroprotection in part, by decreasing the impact of acute smoke inhalation on integrity of neuronal DNA. PMID:22001746

  5. A method for computing the damage level due to the exposure to an airborne chemical with a time-varying concentration.

    PubMed

    Acquesta, Alejandro D; Sánchez, Erica Yanina; Porta, Andres; Jacovkis, Pablo M

    2011-09-01

    The calculation of damage level due to the exposure to a toxic cloud is usually not included in most popular software, or it is included using techniques that do not take into account the variation in concentration over a period of time. In this work, a method is introduced for calculating the temporal evolution of the potential damage level and to obtain a more precise and descriptive estimation of this level. The proposed goal is: to estimate the maximum and minimum damage level experienced by a population due to the exposure to an airborne chemical with a time-varying concentration; to be able to assess the damage level experienced in a progressive way, as the exposure to the airborne chemical occurs. The method relies on transformations of time-concentration pairs on a continuum of damage level curves based on the available guideline levels, obtaining maximum and minimum approximations of the expected damage level for any exposure duration. Consequently, applying this method to transport model output data and demographic information, damage evolution in relation to time and space can be predicted, as well as its effect on the local population, which enables the determination of threat zones. The comparison between the proposed method and the current (Spanish and ALOHA) ones showed that the former can offer a more precise estimation and a more descriptive approach of the potential damage level. This method can be used by atmospheric dispersion models to compute damage level and graphically display the regions exposed to each guideline level on area maps.

  6. Ku80 Counters Oxidative Stress-Induced DNA Damage and Cataract Formation in the Human Lens.

    PubMed

    Smith, Andrew John Oliver; Ball, Simon Sidney Robert; Manzar, Kamal; Bowater, Richard Peter; Wormstone, Ian Michael

    2015-12-01

    Oxidative stress in the human lens leads to a wide range of damage including DNA strand breaks, which are likely to contribute to cataract formation. The protein Ku80 is a fundamental component of the nonhomologous end-joining pathway that repairs DNA double strand breaks. This study investigates the putative impact of Ku80 in cataract prevention in the human lens. The present study used the human lens epithelial cell line FHL124 and whole human lens organ culture. Targeted siRNA was used to deplete Ku80, with Western blot and immunocytochemistry employed to assess Ku80 expression levels. Oxidative stress was induced with hydrogen peroxide and DNA strand breaks measured by alkaline comet assay and γH2AX foci counts. Visual quality of whole human lenses was measured with image analysis software. Expression of Ku80 was predominately found in the cell nucleus of both FHL124 cells and native human lens epithelium. Treatment of FHL124 cells and whole lens cultures with siRNA targeted against Ku80 resulted in a significant knockdown at the protein level. Application of oxidative stress (30 μM H2O2) created more DNA strand breaks when added to Ku80 knockdown cells than in scrambled siRNA control cells as determined by the alkaline comet assay and the number of γH2AX foci. In whole lens cultures, exposure to 1 mM H2O2 resulted in more lens opacity in Ku80 knockdown lenses than match-paired controls. Depletion of Ku80 in the lens through acute change or a consequence of aging is likely to increase levels of DNA strand breaks, which could negatively influence physiological function and promote lens opacity. It is therefore feasible that Ku80 plays a role in retarding cataract formation.

  7. Calcium phosphate formation due to pH-induced adsorption/precipitation switching along salinity gradients

    NASA Astrophysics Data System (ADS)

    Oxmann, J. F.; Schwendenmann, L.

    2014-07-01

    Mechanisms governing phosphorus (P) speciation in coastal sediments remain unknown due to the diversity of coastal environments and poor analytical specificity for P phases. We investigated P speciation along salinity gradients comprising diverse ecosystems in a P-enriched estuary. To determine P load effects on P speciation we compared the high P site with a P-unenriched site. To improve analytical specificity, octacalcium phosphate (OCP), authigenic apatite (carbonate fluorapatite; CFAP) and detrital apatite (fluorapatite) were quantitated in addition to Al/Fe-bound P (Al/Fe-P) and Ca-bound P (Ca-P). Sediment pH primarily affected P fractions across ecosystems and independent of the P status. Increasing pH caused a pronounced downstream transition from adsorbed Al/Fe-P to mineral Ca-P. Downstream decline in Al/Fe-P was counterbalanced by the precipitation of Ca-P. This marked upstream-to-downstream switch occurred at near-neutral sediment pH and was enhanced by increased P loads. Accordingly, the site comparison indicated two location-dependent accumulation mechanisms at the P-enriched site, which mainly resulted in elevated Al/Fe-P at pH < 6.6 (upstream; adsorption) and elevated Ca-P at pH > 6.6 (downstream; precipitation). Enhanced Ca-P precipitation by increased loads was also evident from disproportional accumulation of metastable Ca-P (Ca-PMmeta). The average Ca-Pmeta concentration was six-fold, whereas total Ca-P was only twofold higher at the P-enriched site compared to the P-unenriched site. Species concentrations showed that these largely elevated Ca-Pmeta levels resulted from transformation of fertilizer-derived Al/Fe-P to OCP and CFAP due to decreasing acidity from land to the sea. Formation of OCP and CFAP results in P retention in coastal zones, which may lead to substantial inorganic P accumulation by anthropogenic P input in near-shore sediments.

  8. Authigenic apatite and octacalcium phosphate formation due to adsorption-precipitation switching across estuarine salinity gradients

    NASA Astrophysics Data System (ADS)

    Oxmann, J. F.; Schwendenmann, L.

    2015-02-01

    Mechanisms governing phosphorus (P) speciation in coastal sediments remain largely unknown due to the diversity of coastal environments and poor analytical specificity for P phases. We investigated P speciation across salinity gradients comprising diverse ecosystems in a P-enriched estuary. To determine P load effects on P speciation we compared the high P site with a low P site. Octacalcium phosphate (OCP), authigenic apatite (carbonate fluorapatite, CFAP) and detrital apatite (fluorapatite) were quantitated in addition to Al/Fe-bound P (Al/Fe-P) and Ca-bound P (Ca-P). Gradients in sediment pH strongly affected P fractions across ecosystems and independent of the site-specific total P status. We found a pronounced switch from adsorbed Al/Fe-P to mineral Ca-P with decreasing acidity from land to sea. This switch occurred at near-neutral sediment pH and has possibly been enhanced by redox-driven phosphate desorption from iron oxyhydroxides. The seaward decline in Al/Fe-P was counterbalanced by the precipitation of Ca-P. Correspondingly, two location-dependent accumulation mechanisms occurred at the high P site due to the switch, leading to elevated Al/Fe-P at pH < 6.6 (landward; adsorption) and elevated Ca-P at pH > 6.6 (seaward; precipitation). Enhanced Ca-P precipitation by increased P loads was also evident from disproportional accumulation of metastable Ca-P (Ca-Pmeta) at the high P site. Here, sediments contained on average 6-fold higher Ca-Pmeta levels compared with the low P site, although these sediments contained only 2-fold more total Ca-P than the low P sediments. Phosphorus species distributions indicated that these elevated Ca-Pmeta levels resulted from transformation of fertilizer-derived Al/Fe-P to OCP and CFAP in nearshore areas. Formation of CFAP as well as its precursor, OCP, results in P retention in coastal zones and can thus lead to substantial inorganic P accumulation in response to anthropogenic P input.

  9. Electron Microscopy Study of Stainless Steel Radiation Damage Due to Long-Term Irradation by Alpha Particles Emitted From Plutonium

    SciTech Connect

    Unlu, Kenan; Rios-Martinez, Carlos; Saglam, Mehmet; Hart, Ron R.; Shipp, John D.; Rennie, John

    1998-04-16

    Radiation damage and associated surface and microstructural changes produced in stainless steel encapsulation by high-fluence alpha particle irradiations from weapons-grade plutonium of 316-stainless steel are being investigated.

  10. Primary Radiation Damage Formation in Metals in State-of-the-art Report on Structural Materials Modelling

    SciTech Connect

    Stoller, Roger E; Nordlund, Kai; Melerba, L

    2016-01-01

    The processes that give rise to changes in the microstructure and the physical and mechanical properties of materials exposed to energetic particles are initiated by essentially elastic collisions between atoms in what has been called an atomic displacement cascade. The formation and evolution of this primary radiation damage mechanism are described to provide an overview of how stable defects are formed by displacement cascades, as well as the nature and morphology of the defects themselves. The impact of the primary variables cascade energy and irradiation temperature are discussed, along with a range of secondary factors that can influence damage formation.Radiation-induced changes in microstructure and mechanical properties in structural materials are the result of a complex set of physical processes initiated by the collision between an energetic particle (neutron or ion) and an atom in the lattice. This primary damage event is called an atomic displacement cascade. The simplest description of a displacement cascade is to view it as a series of many billiard-ball-like elastic collisions among the atoms in the material. This chapter describes the formation and evolution of this primary radiation damage mechanism to provide an overview of how stable defects are formed by displacement cascades, as well as the nature and morphology of the defects themselves. The impact of the relevant variables such as cascade energy and irradiation temperature is discussed, and defect formation in different materials is compared.

  11. Damage formation, fatigue behavior and strength properties of ZrO2-based ceramics

    NASA Astrophysics Data System (ADS)

    Kozulin, A. A.; Narikovich, A. S.; Kulkov, S. N.; Leitsin, V. N.; Kulkov, S. S.

    2016-08-01

    It is suggested that a non-destructive testing technique using a three-dimensional X-ray tomography be applied to detecting internal structural defects and monitoring damage formation in a ceramic composite structure subjected to a bending load. Three-point bending tests are used to investigate the fatigue behavior and mechanical and physical properties of medical-grade ZrO2-based ceramics. The bending strength and flexural modulus are derived under static conditions at a loading rate of 2 mm/min. The fatigue strength and fatigue limit under dynamic loading are investigated at a frequency of 10 Hz in three stress ranges: 0.91-0.98, 0.8-0.83, and 0.73-0.77 MPa of the static bending strength. The average values of the bending strength and flexural modulus of sintered specimens are 43 MPa and 22 GPa, respectively. The mechanical properties of the ceramics are found to be similar to those of bone tissues. The testing results lead us to conclude that the fatigue limit obtained from 105 stress cycles is in the range 33-34 MPa, i.e. it accounts for about 75% of the static bending strength for the test material.

  12. Damage formation, fatigue behavior and strength properties of ZrO{sub 2}-based ceramics

    SciTech Connect

    Kozulin, A. A. Kulkov, S. S.; Narikovich, A. S.; Leitsin, V. N.; Kulkov, S. N.

    2016-08-02

    It is suggested that a non-destructive testing technique using a three-dimensional X-ray tomography be applied to detecting internal structural defects and monitoring damage formation in a ceramic composite structure subjected to a bending load. Three-point bending tests are used to investigate the fatigue behavior and mechanical and physical properties of medical-grade ZrO{sub 2}-based ceramics. The bending strength and flexural modulus are derived under static conditions at a loading rate of 2 mm/min. The fatigue strength and fatigue limit under dynamic loading are investigated at a frequency of 10 Hz in three stress ranges: 0.91–0.98, 0.8–0.83, and 0.73–0.77 MPa of the static bending strength. The average values of the bending strength and flexural modulus of sintered specimens are 43 MPa and 22 GPa, respectively. The mechanical properties of the ceramics are found to be similar to those of bone tissues. The testing results lead us to conclude that the fatigue limit obtained from 10{sup 5} stress cycles is in the range 33–34 MPa, i.e. it accounts for about 75% of the static bending strength for the test material.

  13. Laser-induced damage characteristics in fused silica surface due to mechanical and chemical defects during manufacturing processes

    NASA Astrophysics Data System (ADS)

    Li, Yaguo; Yuan, Zhigang; Wang, Jian; Xu, Qiao

    2017-06-01

    Mechanical and chemical defects incurred by grinding and polishing as well as post-processing have been recognized as the most influential culprits that hamper the elevation of laser power/energy in high peak power/energy laser systems. In order to find out the causes for limiting the operational power of laser systems, the effects of these defects on laser damage and removal and mitigation of the defects were investigated in detail in the article. Cracks and scratches were created, annealed, etched and damaged so as to reveal the likely effects of mechanical defects on damage and potential techniques to reduce their influence. The results show that HF-based etching can open and smooth cracks/scratches, improving laser-induced damage threshold (LIDT) at scratches by up to >250%. Thermal annealing did heal, to some extent, cracks but the LIDT is little improved. Both HF-etching and leaching proves to be effective in removing metallic contamination during polishing process and handling of optics, which can "contribute" to damage/damage density in fused silica. However, HF-based etching may degrade surface roughness, from <1 nm to >20 nm under some conditions when >20 μm material was etched away while the surface roughness was perceptibly altered by leaching (<1 nm to 1-2 nm). Although the LIDT might not be directly correlated to each individual kind of metallic contaminants or surface roughness, it is found that the surfaces with the highest LIDT's have some distinguished characteristics: clean surface (almost no metallic contamination) plus very smooth surface (RMS surface roughness: <5 nm). By removing metallic contamination and scratches, surface damage threshold of fused silica can exceed >30 J/cm2 (355 nm @3 ns, beam diameter 400 μm @1/e2), a significant progress.

  14. Analysis of core damage frequency due to external events at the DOE (Department of Energy) N-Reactor

    SciTech Connect

    Lambright, J.A.; Bohn, M.P.; Daniel, S.L. ); Baxter, J.T. ); Johnson, J.J.; Ravindra, M.K.; Hashimoto, P.O.; Mraz, M.J.; Tong, W.H.; Conoscente, J.P. ); Brosseau, D.A. )

    1990-11-01

    A complete external events probabilistic risk assessment has been performed for the N-Reactor power plant, making full use of all insights gained during the past ten years' developments in risk assessment methodologies. A detailed screening analysis was performed which showed that all external events had negligible contribution to core damage frequency except fires, seismic events, and external flooding. A limited scope analysis of the external flooding risk indicated that it is not a major risk contributor. Detailed analyses of the fire and seismic risks resulted in total (mean) core damage frequencies of 1.96E-5 and 4.60E-05 per reactor year, respectively. Detailed uncertainty analyses were performed for both fire and seismic risks. These results show that the core damage frequency profile for these events is comparable to that found for existing commercial power plants if proposed fixes are completed as part of the restart program. 108 refs., 85 figs., 80 tabs.

  15. Utilization of biologically generated acid for drilling fluid damage removal and uniform acid placement across long formation intervals

    SciTech Connect

    Almond, S.W.; Harris, R.E.; Penny, G.S.

    1995-12-31

    A method of drilling damage removal is presented which uses biologically generated acid (BGA) as the stimulation fluid. The BGA solution is not reactive during the actual pumping stage which allows its displacement into the reservoir to be controlled by the relatively low permeability of the near wellbore damage. Catalytic generation of acid occurs at a controlled rate once the BGA has been injected into the formation and results in uniform damage removal around the near wellbore region. The ability of BGA to be generated under a variety of temperature and pressure conditions and the compatibility evaluation of BGA with a variety of commonly used oil and water based drilling muds is first presented to establish some of the operational guidelines for BGA use. Drilling damage removal studies utilizing the modified API linear conductivity flow cell and carbonate material with BGA is presented to demonstrate the effectiveness of this stimulation fluid. Dual core flow test data is then presented which shows BGA`s ability and HCL`s inability to remove drilling damage over long horizontal intervals in carbonate formations.

  16. Phosphoramide mustard exposure induces DNA adduct formation and the DNA damage repair response in rat ovarian granulosa cells

    PubMed Central

    Ganesan, Shanthi; Keating, Aileen F.

    2015-01-01

    Phosphoramide mustard (PM), the ovotoxic metabolite of the anti-cancer agent cyclophosphamide (CPA), destroys rapidly dividing cells by forming NOR-G-OH, NOR-G and G-NOR-G adducts with DNA, potentially leading to DNA damage. A previous study demonstrated that PM induces ovarian DNA damage in rat ovaries. To investigate whether PM induces DNA adduct formation, DNA damage and induction of the DNA repair response, rat spontaneously immortalized granulosa cells (SIGCs) were treated with vehicle control (1% DMSO) or PM (3 or 6 μM) for 24 or 48 h. Cell viability was reduced (P < 0.05) after 48 h of exposure to 3 or 6 μM PM. The NOR-G-OH DNA adduct was detected after 24 h of 6 μM PM exposure, while the more cytotoxic G-NOR-G DNA adduct was formed after 48 h by exposure to both PM concentrations. Phosphorylated H2AX (γH2AX), a marker of DNA double stranded break occurrence, was also increased by PM exposure, coincident with DNA adduct formation. Additionally, induction of genes (Atm, Parp1, Prkdc, Xrcc6, and Brca1) and proteins (ATM, γH2AX, PARP-1, PRKDC, XRCC6, and BRCA1) involved in DNA repair were observed in both a time- and dose-dependent manner. These data support that PM induces DNA adduct formation in ovarian granulosa cells, induces DNA damage and elicits the ovarian DNA repair response. PMID:25497287

  17. Identification of the formation phases of filamentary damage induced by nanosecond laser pulses in bulk fused silica

    SciTech Connect

    Shen, Chao; Xu, Zhongjie; Chambonneau, Maxime E-mail: jiangtian198611@163.com; Cheng, Xiang'ai; Jiang, Tian E-mail: jiangtian198611@163.com

    2015-09-14

    Employing a pump-probe polarization-based two-frame shadowgraphy setup, the formation of filamentary damage induced in bulk fused silica by a nanosecond pulse at 1064 nm is investigated with a picosecond probe. Three different phases are exhibited in the damage experiments. The first phase is the formation of a micrometric plasma channel along the laser direction during the beginning of the pulse likely caused by multi-photon ionization. This channel exhibits growth during ∼400 ps, and the newly grown plasma is discrete. Then, during the end of the pulse, this channel evolves into a tadpole-like morphology showing an elliptical head upstream the laser flux followed by a thin tail. This observed asymmetry is attributed to shielding effects caused by both the plasma and hot modified silica. Once the damage shows its almost final morphology, a last phase consists in the launch of a pressure wave enlarging it after the laser pulse. The physical mechanisms that might be involved in the formation of plasma channels are discussed. The experimental data are first confronted to the moving breakdown model which overestimates the filamentary damage length. Finally, taking into account the temporal shape of the laser pulses, the coupling between Kerr-induced self-focusing and stimulated Brillouin scattering is discussed to interpret the observations.

  18. Acoustic and Electrical Property Changes Due to Microbial Growth and Biofilm Formation in Porous Media

    EPA Science Inventory

    A laboratory study was conducted to investigate the effect of microbial growth and biofilm formation on compressional waves, and complex conductivity during stimulated microbial growth. Over the 29 day duration of the experiment, compressional wave amplitudes and arrival times f...

  19. Acoustic and Electrical Property Changes Due to Microbial Growth and Biofilm Formation in Porous Media

    EPA Science Inventory

    A laboratory study was conducted to investigate the effect of microbial growth and biofilm formation on compressional waves, and complex conductivity during stimulated microbial growth. Over the 29 day duration of the experiment, compressional wave amplitudes and arrival times f...

  20. Formation, Accumulation, and Hydrolysis of Endogenous and Exogenous Formaldehyde-Induced DNA Damage

    PubMed Central

    Yu, Rui; Lai, Yongquan; Hartwell, Hadley J.; Moeller, Benjamin C.; Doyle-Eisele, Melanie; Kracko, Dean; Bodnar, Wanda M.; Starr, Thomas B.; Swenberg, James A.

    2015-01-01

    Formaldehyde is not only a widely used chemical with well-known carcinogenicity but is also a normal metabolite of living cells. It thus poses unique challenges for understanding risks associated with exposure. N2-hydroxymethyl-dG (N2-HOMe-dG) is the main formaldehyde-induced DNA mono-adduct, which together with DNA-protein crosslinks (DPCs) and toxicity-induced cell proliferation, play important roles in a mutagenic mode of action for cancer. In this study, N2-HOMe-dG was shown to be an excellent biomarker for direct adduction of formaldehyde to DNA and the hydrolysis of DPCs. The use of inhaled [13CD2]-formaldehyde exposures of rats and primates coupled with ultrasensitive nano ultra performance liquid chromatography-tandem mass spectrometry permitted accurate determinations of endogenous and exogenous formaldehyde DNA damage. The results show that inhaled formaldehyde only reached rat and monkey noses, but not tissues distant to the site of initial contact. The amounts of exogenous adducts were remarkably lower than those of endogenous adducts in exposed nasal epithelium. Moreover, exogenous adducts accumulated in rat nasal epithelium over the 28-days exposure to reach steady-state concentrations, followed by elimination with a half-life (t1/2) of 7.1 days. Additionally, we examined artifact formation during DNA preparation to ensure the accuracy of nonlabeled N2-HOMe-dG measurements. These novel findings provide critical new data for understanding major issues identified by the National Research Council Review of the 2010 Environmental Protection Agency’s Draft Integrated Risk Information System Formaldehyde Risk Assessment. They support a data-driven need for reflection on whether risks have been overestimated for inhaled formaldehyde, whereas underappreciating endogenous formaldehyde as the primary source of exposure that results in bone marrow toxicity and leukemia in susceptible humans and rodents deficient in DNA repair. PMID:25904104

  1. Dose rate effects on damage formation in ion-implanted gallium arsenide

    SciTech Connect

    Haynes, T.E.; Holland, O.W.

    1990-09-01

    The residual damage in GaAs was measured by ion channeling following implantation of either 100 keV {sup 30}Si{sup +} at temperatures of 300K or 77K, or 360 keV {sup 120}Sn{sup +} at 300K. For room-temperature Si implants and fluences between 1 and 10 {times} 10{sup 14} Si/cm{sup 2}, the amount of damage created was strongly dependent upon the ion current density, which was varied between 0.05 and 12 {mu}A/cm{sup 2}. Two different stages of damage growth were identified by an abrupt increase in the damage growth rate as a function of fluence, and the threshold fluence for the onset of the second stage was found to be dependent on the dose rate. The dose rate effect on damage was substantially weaker for {sup 120}Sn{sup +} implants and was negligible for Si implants at 77K. The damage was found to be most sensitive to the average current density, demonstrating that the defects which are the precursors to the residual dose-rate dependent damage have active lifetimes of at least 3 {times} 10{sup {minus}4} s. The dose rate effect and its variation with ion mass and temperature are discussed in the context of homogeneous nucleation and growth of damage during ion irradiation.

  2. Evidence of authigenic vivianite formation in a recent lake sediment due to an iron amendment

    NASA Astrophysics Data System (ADS)

    Rothe, Matthias; Frederichs, Thomas; Eder, Michaela; Kleeberg, Andreas; Hupfer, Michael

    2014-05-01

    Pore water chemistry and equilibrium calculations indicated supersaturation of the ferrous iron phosphate mineral vivianite throughout the upper 30 cm of the iron-rich lake sediments of dimictic lake Groß-Glienicker See, Berlin (Germany). Phosphorus (P) bound in the crystal lattice of the mineral is supposed to be immobilized since vivianite is stable under anoxic, reducing sedimentary conditions. Thus, vivianite formation can be an important process contributing to P retention during early diagenesis. Application of a heavy-liquid separation enabled to identify vivianite by means of X-ray diffraction. Electron micrographs showed spherical nodules consisting of platy- and needle-shaped crystal aggregates with diameters between 50 and 120 μm. Inclusions of diatom shells and other organic debris confirmed the authigenic origin of the dark blue coloured nodules. Vivianite deposits were restricted to the upper 22 cm of the sediment although supersaturation even increased in subjacent pore waters. The high enrichment of vivianite aggregates after sediment preparation combined with magnetic hysteresis measurements allowed to assess the significance of vivianite formation for P burial in aquatic systems. From our results we conclude that vivianite formation was triggered by an artificial iron amendment more than 20 years ago that aimed at reducing the P content of the lake's water body. Furthermore, our results indicate that vivianite formation is located closely beneath the sediment-water interface and that equilibrium calculations, i.e. supersaturated pore water, alone cannot serve as a reliable predictor for the in situ formation of vivianite.

  3. The Cartography of UV-induced DNA Damage Formation and DNA Repair.

    PubMed

    Hu, Jinchuan; Adar, Sheera

    2017-01-01

    DNA damage presents a barrier to DNA-templated biochemical processes, including gene expression and faithful DNA replication. Compromised DNA repair leads to mutations, enhancing the risk for genetic diseases and cancer development. Conventional experimental approaches to study DNA damage required a researcher to choose between measuring bulk damage over the entire genome, with little or no resolution regarding a specific location, and obtaining data specific to a locus of interest, without a global perspective. Recent advances in high-throughput genomic tools overcame these limitations and provide high-resolution measurements simultaneously across the genome. In this review, we discuss the available methods for measuring DNA damage and their repair, focusing on genomewide assays for pyrimidine photodimers, the major types of damage induced by ultraviolet irradiation. These new genomic assays will be a powerful tool in identifying key components of genome stability and carcinogenesis. © 2016 The American Society of Photobiology.

  4. Deposit formation due to instability and contamination of raw materials in alkali-treated light distillates

    SciTech Connect

    Hessam, K.

    1986-01-01

    Alkali treating of petroleum distillates is carried out to obtain the advantages of the product purity and to improve performance. The use and quality of alkaline solutions must be controlled since metal ions present as impurities can catalyze low temperature oxidation and polymerization of olefinic compounds; leading to formation of heavy emulsions which tend to deposit in hydrocarbon phases and eventually to block the handling systems. The effects of the variable factors ''time, temperature, antioxidant and anticorrosion additives'' were studied. The addition of a small amount of methanol was found to retard the deposit formation.

  5. Final Report - Modeling the Physics of Damage Cluster Formation in a Cellular Environment Modeling the Physics of Damage Cluster Formation in a Cellular Environment

    SciTech Connect

    L.H. Toburen, Principal Investigator; J.L. Shinpaugh; M. Dingfelder; and G. Lapicki; Co-Investigators

    2007-01-07

    Modern tools of radiobiology are leading to many new discoveries regarding how cells and tissues respond to radiation exposure. We can now irradiate single cells and observe responses in adjacent cells. We can also measure clusters of radiation damage produced in DNA. Our primary objective has been to understand the underling physics associated with these new biological responses. The primary tools available to describe the initial spatial pattern of damage formed by the absorption of ionizing radiation are based on Monte Carlo simulation of the structure of charged particle tracks. Although many Monte Carlo codes exist and considerable progress is being made in the incorporation of detailed macromolecular target structures into these codes, much of the interaction physics is still based on gas phase measurements and/or untested theoretical calculations that focus on water as the transport medium. Our objectives were threefold, (1) to expand the applicability of Monte Carlo track structure simulation to tissue-like material beyond the current focus on water, (2) to incorporate the most recent experimental information on electron interactions in biologically relevant material, and (3) to compare recent measurements of electron emissions induced by charged particles in thin foils with Monte Carlo predictions. We addressed these research objectives in three ways. First we applied theoretical techniques, similar to those used to derive data for water, to obtain cross sections for other condensed phase materials. This served two purposes. One was to provide testability of the theoretical technique by comparison to existing experimental data for electron transport (similar data does not exist for water), and the other was to expand the target database for use in modeling tissue. Second, we carefully reviewed published data, and ongoing experiments, for electron interaction cross-sections in biologically relevant condensed phase material. Results for low-energy electron

  6. Reactivity of Damaged Pyrimidines: DNA Cleavage via Hemiaminal Formation at the C4 Positions of the Saturated Thymine of Spore Photoproduct and Dihydrouridine

    PubMed Central

    2015-01-01

    Described here are mechanistic details of the chemical reactivities of two modified/saturated pyrimidine residues that represent naturally occurring forms of DNA damage: 5-thyminyl-5,6-dihydrothymine, commonly referred to as the “spore photoproduct” (SP), and 5,6-dihydro-2′-deoxyuridine (dHdU), formed via ionizing radiation damage to cytosine under anoxic conditions and also serving as a general model of saturated pyrimidine residues. It is shown that due to the loss of the pyrimidine C5–C6 double bond and consequent loss of ring aromaticity, the C4 position of both these saturated pyrimidines is prone to the formation of a hemiaminal intermediate via water addition. Water addition is facilitated by basic conditions; however, it also occurs at physiological pH at a slower rate. The hemiaminal species so-formed subsequently converts to a ring-opened hydrolysis product through cleavage of the pyrimidine N3–C4 bond. Further decomposition of this ring-opened product above physiological pH leads to DNA strand break formation. Taken together, these results suggest that once the aromaticity of a pyrimidine residue is lost, the C4 position becomes a “hot spot” for the formation of a tetrahedral intermediate, the decay of which triggers a cascade of elimination reactions that can under certain conditions convert a simple nucleobase modification into a DNA strand break. PMID:25127075

  7. Impaired representation of geometric relationships in humans with damage to the hippocampal formation.

    PubMed

    Finke, Carsten; Ostendorf, Florian; Braun, Mischa; Ploner, Christoph J

    2011-01-01

    The pivotal role of the hippocampus for spatial memory is well-established. However, while neurophysiological and imaging studies suggest a specialization of the hippocampus for viewpoint-independent or allocentric memory, results from human lesion studies have been less conclusive. It is currently unclear whether disproportionate impairment in allocentric memory tasks reflects impairment of cognitive functions that are not sufficiently supported by regions outside the medial temporal lobe or whether the deficits observed in some studies are due to experimental factors. Here, we have investigated whether hippocampal contributions to spatial memory depend on the spatial references that are available in a certain behavioral context. Patients with medial temporal lobe lesions affecting systematically the right hippocampal formation performed a series of three oculomotor tasks that required memory of a spatial cue either in retinal coordinates or relative to a single environmental reference across a delay of 5000 ms. Stimulus displays varied the availability of spatial references and contained no complex visuo-spatial associations. Patients showed a selective impairment in a condition that critically depended on memory of the geometric relationship between spatial cue and environmental reference. We infer that regions of the medial temporal lobe, most likely the hippocampal formation, contribute to behavior in conditions that exceed the potential of viewpoint-dependent or egocentric representations. Apparently, this already applies to short-term memory of simple geometric relationships and does not necessarily depend on task difficulty or integration of landmarks into more complex representations. Deficient memory of basic geometric relationships may represent a core deficit that contributes to impaired performance in allocentric spatial memory tasks.

  8. Phosphoramide mustard exposure induces DNA adduct formation and the DNA damage repair response in rat ovarian granulosa cells

    SciTech Connect

    Ganesan, Shanthi Keating, Aileen F.

    2015-02-01

    Phosphoramide mustard (PM), the ovotoxic metabolite of the anti-cancer agent cyclophosphamide (CPA), destroys rapidly dividing cells by forming NOR-G-OH, NOR-G and G-NOR-G adducts with DNA, potentially leading to DNA damage. A previous study demonstrated that PM induces ovarian DNA damage in rat ovaries. To investigate whether PM induces DNA adduct formation, DNA damage and induction of the DNA repair response, rat spontaneously immortalized granulosa cells (SIGCs) were treated with vehicle control (1% DMSO) or PM (3 or 6 μM) for 24 or 48 h. Cell viability was reduced (P < 0.05) after 48 h of exposure to 3 or 6 μM PM. The NOR-G-OH DNA adduct was detected after 24 h of 6 μM PM exposure, while the more cytotoxic G-NOR-G DNA adduct was formed after 48 h by exposure to both PM concentrations. Phosphorylated H2AX (γH2AX), a marker of DNA double stranded break occurrence, was also increased by PM exposure, coincident with DNA adduct formation. Additionally, induction of genes (Atm, Parp1, Prkdc, Xrcc6, and Brca1) and proteins (ATM, γH2AX, PARP-1, PRKDC, XRCC6, and BRCA1) involved in DNA repair were observed in both a time- and dose-dependent manner. These data support that PM induces DNA adduct formation in ovarian granulosa cells, induces DNA damage and elicits the ovarian DNA repair response. - Highlights: • PM forms ovarian DNA adducts. • DNA damage marker γH2AX increased by PM exposure. • PM induces ovarian DNA double strand break repair.

  9. Dysfunction of Endothelial Progenitor Cells from Smokers and Chronic Obstructive Pulmonary Disease Patients Due to Increased DNA Damage and Senescence

    PubMed Central

    Paschalaki, Koralia E; Starke, Richard D; HU, Yanhua; Mercado, Nicolas; Margariti, Andriana; Gorgoulis, Vassilis G; Randi, Anna M; Barnes, Peter J

    2013-01-01

    Cardiovascular disease (CVD) is a major cause of death in smokers, particularly in those with chronic obstructive pulmonary disease (COPD). Circulating endothelial progenitor cells (EPC) are required for endothelial homeostasis, and their dysfunction contributes to CVD. To investigate EPC dysfunction in smokers, we isolated and expanded blood outgrowth endothelial cells (BOEC) from peripheral blood samples from healthy nonsmokers, healthy smokers, and COPD patients. BOEC from smokers and COPD patients showed increased DNA double-strand breaks and senescence compared to nonsmokers. Senescence negatively correlated with the expression and activity of sirtuin-1 (SIRT1), a protein deacetylase that protects against DNA damage and cellular senescence. Inhibition of DNA damage response by silencing of ataxia telangiectasia mutated (ATM) kinase resulted in upregulation of SIRT1 expression and decreased senescence. Treatment of BOEC from COPD patients with the SIRT1 activator resveratrol or an ATM inhibitor (KU-55933) also rescued the senescent phenotype. Using an in vivo mouse model of angiogenesis, we demonstrated that senescent BOEC from COPD patients are dysfunctional, displaying impaired angiogenic ability and increased apoptosis compared to cells from healthy nonsmokers. Therefore, this study identifies epigenetic regulation of DNA damage and senescence as pathogenetic mechanisms linked to endothelial progenitors' dysfunction in smokers and COPD patients. These defects may contribute to vascular disease and cardiovascular events in smokers and could therefore constitute therapeutic targets for intervention. PMID:23897750

  10. Star Formation In The Centers Of Galaxies Due To Secular Evolution

    NASA Astrophysics Data System (ADS)

    Fisher, David; Drory, Niv; Kormendy, John

    2006-05-01

    The two fundamental channels for disk galaxy evolution are environmentally driven hierarchical clustering (galaxy mergers) and internally driven secular evolution. Ellipticals and "classical bulges" are believed to form by mergers. "Pseudobulges" are observed to be more disk-like than classical bulges: they are flatter, they rotate very rapidly, and they have embedded bars, spiral structure, and ongoing star formation. They are the likely products of slow ("secular") rearrangement of disks by bars and oval distortions. Note that pseudobulges can form only if it has been a long time since the last major merger. This qualitative picture is well supported by observations. But, what is the relative importance of mergers and secular evolution in building bulges -- quantitatively? We propose to measure star formation rates in classical bulges and pseudobulges using the far-infrared fluxes observed with MIPS. Additionally, we use mid-infared IRAC imaging to resolve star-forming substructure within these bulges. To measure star formation rates we use published warm dust SED calibrations (Dale and Helou 2002; Wu et al 2005) as well as any that are still under development. Our purpose is to measure pseudobulge growth rates in Sa, Sb, and Sbc galaxies, and to tie together star formation rates with other indicators of secular evolution. Estimating pseudobulge growth time is the necessary next step in determing the relative importance of major mergers and secular evolution in bulge formation. A key to our strategy is the choice of galaxy sample. We propose to observe matched triples of the nearest giant galaxies that have strong, weak, and no obvious driving agents for internal evolution; i.e. galaxies that are barred, globally oval, and unbarred, respectively. Our sample will provide a valuable augmentation of archive data, completing observations of triples where necessary. The result is to increase the return of previous investments for a wider variety of science

  11. Small bowel obstruction due to phytobezoar formation within meckel diverticulum: CT findings

    SciTech Connect

    Frazzini, V.I. Jr.; English, W.J.; Bashist, B.; Moore, E.

    1996-05-01

    Intestinal obstruction due to a phytobezoar within a Meckel diverticulum is exceedingly rare, with only seven reported cases in the surgical literature. The most important precipitating factor is the ingestion of agents high in fiber and cellulose. Small bowel obstruction in all but one case was due to retrograde propagation of the bezoar into the small bowel lumen. We report the clinical and CT findings in such a patient following a vegetarian diet. 14 refs., 2 figs.

  12. Estimating Damage Cost of Net Primary Production due to Climate Change and Ozone(O3) Effect

    NASA Astrophysics Data System (ADS)

    Park, J. H.; Lee, D. K.; Park, C.; Sung, S.; Kim, H. G.; Mo, Y.; Kim, S.; Kil, S.

    2016-12-01

    Forests are absorbing and storing carbon dioxide (CO2) through photosynthesis. The forests are not only preventing global warming but also influencing temperature, precipitation and humidity (Costanza et al., 1997; de Groot et al., 2002). Also the forests are recognized as a carbon sink internationally (van Kooten, 2009). The Korean Government supports the economic activity such as carbon offset projects in accordance with 'ACT ON THE MANAGEMENT AND IMPROVEMENT OF CARBON SINK' Article27 (Korea Forest Service, 2013) and aims to make a policy which improves the CO2 capacity of forest for Paris Agreement discussed in UNFCCC COP21, December 2015 (Korea Forest Service, 2015). However, the social-economic activities make to increase aerosols as well as greenhouse gases significantly since the industrial revolution, as a result, the chemical composition of the atmosphere has changed significantly. According to the resent studies, not only CO2 but atmospheric chemistries such as ozone (O3), aerosol and black carbon can be an important factor causing climate change (Hansen et al., 2007; IPCC, 2007). In the past, acid rain affected on forest, but in these days, O3, nitrogen oxide (NOX) and sulfur oxide (SOX) are the most threatening factors on forest ecosystem (Lee et al, 2011). In particular, O3accounts for most of the photochemical products and causes a direct significant impact or damage on the plant because of high toxicity (Han et al., 2006). The research questions of this study are "How does O3 effects on forest productivity in the present and future? " What is the damage cost by the O3 effect in the future? In this study, we developed a statistical model using the parameters which effect on the forest productivity. We estimated the forest productivity using on the derived model in the present and future on a SSP scenarios. Lastly, we evaluated the economic effect or damage cost of O3effect by introducing the concept of climate insurance. The average forest

  13. Formation, Accumulation, and Hydrolysis of Endogenous and Exogenous Formaldehyde-Induced DNA Damage.

    PubMed

    Yu, Rui; Lai, Yongquan; Hartwell, Hadley J; Moeller, Benjamin C; Doyle-Eisele, Melanie; Kracko, Dean; Bodnar, Wanda M; Starr, Thomas B; Swenberg, James A

    2015-07-01

    Formaldehyde is not only a widely used chemical with well-known carcinogenicity but is also a normal metabolite of living cells. It thus poses unique challenges for understanding risks associated with exposure. N(2-)hydroxymethyl-dG (N(2)-HOMe-dG) is the main formaldehyde-induced DNA mono-adduct, which together with DNA-protein crosslinks (DPCs) and toxicity-induced cell proliferation, play important roles in a mutagenic mode of action for cancer. In this study, N(2)-HOMe-dG was shown to be an excellent biomarker for direct adduction of formaldehyde to DNA and the hydrolysis of DPCs. The use of inhaled [(13)CD2]-formaldehyde exposures of rats and primates coupled with ultrasensitive nano ultra performance liquid chromatography-tandem mass spectrometry permitted accurate determinations of endogenous and exogenous formaldehyde DNA damage. The results show that inhaled formaldehyde only reached rat and monkey noses, but not tissues distant to the site of initial contact. The amounts of exogenous adducts were remarkably lower than those of endogenous adducts in exposed nasal epithelium. Moreover, exogenous adducts accumulated in rat nasal epithelium over the 28-days exposure to reach steady-state concentrations, followed by elimination with a half-life (t1/2) of 7.1 days. Additionally, we examined artifact formation during DNA preparation to ensure the accuracy of nonlabeled N(2)-HOMe-dG measurements. These novel findings provide critical new data for understanding major issues identified by the National Research Council Review of the 2010 Environmental Protection Agency's Draft Integrated Risk Information System Formaldehyde Risk Assessment. They support a data-driven need for reflection on whether risks have been overestimated for inhaled formaldehyde, whereas underappreciating endogenous formaldehyde as the primary source of exposure that results in bone marrow toxicity and leukemia in susceptible humans and rodents deficient in DNA repair. © The Author 2015

  14. Optical doping and damage formation in AlN by Eu implantation

    NASA Astrophysics Data System (ADS)

    Lorenz, K.; Alves, E.; Gloux, F.; Ruterana, P.; Peres, M.; Neves, A. J.; Monteiro, T.

    2010-01-01

    AlN films grown on sapphire were implanted with 300 keV Eu ions to fluences from 3×1014 to 1.4×1017 atoms/cm2 in two different geometries: "channeled" along the c-axis and "random" with a 10° angle between the ion beam and the surface normal. A detailed study of implantation damage accumulation is presented. Strong ion channeling effects are observed leading to significantly decreased damage levels for the channeled implantation within the entire fluence range. For random implantation, a buried amorphous layer is formed at the highest fluences. Red Eu-related photoluminescence at room temperature is observed in all samples with highest intensities for low damage samples (low fluence and channeled implantation) after annealing. Implantation damage, once formed, is shown to be stable up to very high temperatures.

  15. Formation of laves phase in a refractory austenitic steel due to long-term heating

    NASA Astrophysics Data System (ADS)

    Tarasenko, L. V.; Shal'kevich, A. B.

    2011-07-01

    Steels of the Fe - Cr - Ni -Mo - Nb - Al - C system are studied by methods of phase physicochemical analysis and electron microscopy with the aim to determine the causes of changes in mechanical properties after long-term heating at a temperature of 600 - 700°C. Grain-boundary formation of particles of a Laves phase is shown to cause decrease in the impact toughness and transformation of particles of γ'-phase under conditions of creep. The effect of alloying elements on the chemical composition of the multicomponent Laves phase is studied depending on the temperatures of hardening, aging, and subsequent heating. Concentration correspondence between the chemical composition of the austenite and the intermetallic tcp phase formed in aging is discovered. A computational scheme for predicting the possibility of formation of Laves phases in multicomponent alloys is suggested.

  16. Electromagnetic radiation due to naked singularity formation in self-similar gravitational collapse

    SciTech Connect

    Mitsuda, Eiji; Yoshino, Hirotaka; Tomimatsu, Akira

    2005-04-15

    Dynamical evolution of test fields in background geometry with a naked singularity is an important problem relevant to the Cauchy horizon instability and the observational signatures different from black hole formation. In this paper we study electromagnetic perturbations generated by a given current distribution in collapsing matter under a spherically symmetric self-similar background. Using the Green's function method, we construct the formula to evaluate the outgoing energy flux observed at the future null infinity. The contributions from 'quasinormal' modes of the self-similar system as well as 'high-frequency' waves are clarified. We find a characteristic power-law time evolution of the outgoing energy flux which appears just before naked singularity formation and give the criteria as to whether or not the outgoing energy flux diverges at the future Cauchy horizon.

  17. Characteristics of magnetic island formation due to resistive interchange instability in helical plasma

    SciTech Connect

    Ueda, R.; Matsumoto, Y.; Itagaki, M.; Oikawa, S.; Watanabe, K. Y.; Sato, M.

    2014-05-15

    Focusing attention on the magnetic island formation, we investigate the characteristics of the resistive interchange magnetohydrodynamics instabilities, which would limit a high beta operational regime in helical type fusion reactors. An introduction of a new index, i.e., the ratio of the magnetic fluctuation level to the radial displacement, enables us to make a systematic analysis on the magnetic island formation in the large helical device-like plasmas during the linear growth phase; (i) the interchange instability with the second largest growth rate makes the magnetic island larger than that with the largest growth rate when the amplitude of the radial displacement in both cases is almost the same as each other; (ii) applied to a typical tearing instability, the index is smaller than that for the interchange instability with the second largest growth rate.

  18. Underground Excavation Behaviour of the Queenston Formation: Tunnel Back Analysis for Application to Shaft Damage Dimension Prediction

    NASA Astrophysics Data System (ADS)

    Perras, Matthew A.; Wannenmacher, Helmut; Diederichs, Mark S.

    2015-07-01

    The Niagara Tunnel Project (NTP) is a 10.1 km long water-diversion tunnel in Niagara Falls, Ontario, which was excavated by a 7.2 m radius tunnel boring machine. Approximately half the tunnel length was excavated through the Queenston Formation, which locally is a shale to mudstone. Typical overbreak depths ranged between 2 and 4 m with a maximum of 6 m observed. Three modelling approaches were used to back analyse the brittle failure process at the NTP: damage initiation and spalling limit, laminated anisotropy modelling, and ubiquitous joint approaches. Analyses were conducted for three tunnel chainages: 3 + 000, 3 + 250, and 3 + 500 m because the overbreak depth increased from 2 to 4 m. All approaches produced similar geometries to those measured. The laminated anisotropy modelling approach was able to produced chord closures closest to those measured, using a joint normal to shear stiffness ratio between 1 and 2. This understanding was applied to a shaft excavation model in the Queenston Formation at the proposed Deep Geological Repository (DGR) site for low and intermediate level nuclear waste storage in Canada. The maximum damage depth was 1.9 m; with an average of 1.0 m. Important differences are discussed between the tunnel and shaft orientation with respect to bedding. The models show that the observed normalized depth of failure at the NTP would over-predict the depth of damage expected in the Queenston Formation at the DGR.

  19. Changes in the halo formation rates due to features in the primordial spectrum

    SciTech Connect

    Hazra, Dhiraj Kumar

    2013-03-01

    Features in the primordial scalar power spectrum provide a possible roadway to describe the outliers at the low multipoles in the WMAP data. Apart from the CMB angular power spectrum, these features can also alter the matter power spectrum and, thereby, the formation of the large scale structure. Carrying out a complete numerical analysis, we investigate the effects of primordial features on the formation rates of the halos. We consider a few different inflationary models that lead to features in the scalar power spectrum and an improved fit to the CMB data, and analyze the corresponding imprints on the formation of halos. Performing a Markov Chain Monte Carlo analysis with the WMAP seven year data and the SDSS halo power spectrum from LRG DR7 for the models of our interest, we arrive at the parameter space of the models allowed by the data. We illustrate that, inflationary potentials, such as the quadratic potential with sinusoidal modulations and the axion monodromy model, which generate certain repeated, oscillatory features in the inflationary perturbation spectrum, do not induce a substantial difference in the number density of halos at their best fit values, when compared with, say, a nearly scale invariant spectrum as is generated by the standard quadratic potential. However, we find that the number density and the formation rates of halos change by about 13–22% for halo masses ranging over 10{sup 4}–10{sup 14} M{sub s}un, for potential parameters that lie within 2-σ around the best fit values arrived at from the aforesaid joint constraints. We briefly discuss the implications of our results.

  20. Self-consistent orogenic wedge formation and shear zone propagation due to thermal softening

    NASA Astrophysics Data System (ADS)

    Jaquet, Yoann; Duretz, Thibault; Schmalholz, Stefan M.

    2016-04-01

    We present two dimensional numerical simulations of orogenic wedge formation for a viscoelastoplastic lithosphere under compression. The thermo-mechanical model is based on the principle of energy conservation and includes temperature-dependent rheologies. With this approach, shear zones caused by thermal softening develop spontaneously in the absence of strain softening. The initial locus of shear localization is controlled by either lateral temperature variations (100°C) at the model base or by lateral variations in crustal thickness. The first episode of strain localization occurs after 15% bulk shortening. With ongoing strain, a series of shear zones arise and propagate towards the foreland leading to the self-consistent formation of an orogenic wedge. We investigate the impact of bulk shortening rates, erosion and rheology on the dynamics of wedge formation, the associated topography and uplift rates. The maximum topography reaches up to 10 km and the surface morphology evolves according to shear zone activation and deactivation. Uplift rates are transient and peak values are maintained only on very short time scales. A running average of the uplift rate versus time curves with a time-window of 4 My provides average uplift rates in the order of a few millimeters per year. Erosion is an important parameter for the formation and the evolution of the wedge (e.g. can control the spacing of shear zones by modifying crustal thickness). Rheological parameters, such as the friction angle or the upper crustal viscosity, control the occurrence of strain localization. Bulk shortening rates between 10-15 and 10-16 s-1 do not have a major impact on the resulting wedge structure.

  1. Changes in the halo formation rates due to features in the primordial spectrum

    NASA Astrophysics Data System (ADS)

    Hazra, Dhiraj Kumar

    2013-03-01

    Features in the primordial scalar power spectrum provide a possible roadway to describe the outliers at the low multipoles in the WMAP data. Apart from the CMB angular power spectrum, these features can also alter the matter power spectrum and, thereby, the formation of the large scale structure. Carrying out a complete numerical analysis, we investigate the effects of primordial features on the formation rates of the halos. We consider a few different inflationary models that lead to features in the scalar power spectrum and an improved fit to the CMB data, and analyze the corresponding imprints on the formation of halos. Performing a Markov Chain Monte Carlo analysis with the WMAP seven year data and the SDSS halo power spectrum from LRG DR7 for the models of our interest, we arrive at the parameter space of the models allowed by the data. We illustrate that, inflationary potentials, such as the quadratic potential with sinusoidal modulations and the axion monodromy model, which generate certain repeated, oscillatory features in the inflationary perturbation spectrum, do not induce a substantial difference in the number density of halos at their best fit values, when compared with, say, a nearly scale invariant spectrum as is generated by the standard quadratic potential. However, we find that the number density and the formation rates of halos change by about 13-22% for halo masses ranging over 104-1014 Msolar, for potential parameters that lie within 2-σ around the best fit values arrived at from the aforesaid joint constraints. We briefly discuss the implications of our results.

  2. On the formation and ordering of ``superabundant`` vacancies in palladium due to hydrogen absorption

    SciTech Connect

    Oates, W.A.; Wenzl, H.

    1995-07-15

    The formation of superabundant vacancies in metals can be driven by hydrogen incorporation on the interstitial sublattice. In order to achieve this, it is essential to have a sufficiently high hydrogen chemical potential so that effectively all the available interstitial sites are occupied. The concomitant formation of high concentrations of vacancies on the metal sublattice is then controlled by the coupling of the vacancy chemical potentials on the metal and interstitial sublattices by the Schottky equilibrium condition. This formation of excessive concentrations of vacancies on the host metal lattice is expected to be a general phenomenon which, if the system can achieve vacancy equilibrium with external or internal sinks, will occur as soon as the interstitial sublattice approaches complete filling. This means that the hydrogen/metal ratio will exceed that normally expected for a complete filling of the interstitial sites being considered. Once a high concentration of vacancies has been formed, then an effective repulsive interaction between the vacancies on the metal sublattice may give rise to vacancy ordering at lower temperatures. This interpretation is in good agreement with the experimental results of Fukai and Okuma for the Pd-H system. The authors estimate that they have reached a hydrogen/metal ratio of {approx} 1.2, which they have shown to be quite feasible at the H{sub 2}(g) pressures and temperatures used in their experiments.

  3. Periodic Colony Formation of Bacteria Due to their Cell Reproduction and Movement

    NASA Astrophysics Data System (ADS)

    Itoh, H.; Wakita, J.; Watanabe, K.; Matsuyama, T.; Matsushita, M.

    We have experimentally investigated periodic pattern formation produced by bacterial species Proteus mirabilis, which forms concentric-ring-like colonies by repeating migration and rest alternately on the surface of a solid agar medium. We distinguish three phases (initial lag phase, the following migration and consolidation phases that appear alternately) for the colony growth. Here we mainly used physical approaches in order to try to understand the formation of concentric-ring-like colonies, such as cutting the part of a colony during its growth. Global chemical signals governing the colony formation from the center were not found. We also checked phase entrainment quantitatively by letting two colonies collide with each other and confirmed that it does not take place in macroscopic scales. When we cut a colony just behind the migrating front shortly after the migration started, the migration ended earlier and the following consolidation lasted longer. However, the following cycles were not influenced by the cut, i.e., the following migration and consolidation phases were both found to return normal. The cut results in the stop of supply of cell population to the migrating front by internal waves. In fact the cell population on the new terrace during the first migration after the cut was less than that without cut. Furthermore, the cell population density was found to be recovered to the ordinary value by the end of the consolidation. All these experimental results suggest that the most important factor for the repetition of migration and consolidation phases is the cell population density.

  4. Void formation in amorphous germanium due to high electronic energy deposition

    SciTech Connect

    Gaertner, K.; Joehrens, J.; Steinbach, T.; Schnohr, C. S.; Wesch, W.; Ridgway, M. C.

    2011-06-01

    The effect of high electronic energy deposition in amorphous germanium has been studied experimentally by Au irradiation with ion energies of up to 185 MeV and different angles of incidence and by molecular dynamics computer simulations. In both cases, the energy deposition leads to void formation accompanied by strong swelling of the amorphous germanium. The simulation results prove that the formation of the voids is mainly based on a shock wave mechanism and the swelling is determined by the competing processes of the formation and growth of voids on the one hand and the shrinking and annihilation of voids on the other hand. In full agreement between experiment and simulation, the amount of the swelling is a linear function of the total energy deposited into electronic processes and there exists a threshold value of the electronic energy loss per ion and depth for swelling. A comparison of the threshold values obtained by the experiment and the simulation suggests that approximately 20% of the energy deposited into electronic processes is converted into atomic motion.

  5. Radiation damage of the Kokchetav diamonds due to α-particles from zircon - for proper understanding of spectroscopic variations of metamorphic diamonds

    NASA Astrophysics Data System (ADS)

    Shimizu, R.; Ogasawara, Y.

    2013-12-01

    .g., Orwa et al., 2000). Therefore our results strongly suggest that radiation damage predominantly due to α-particle emission from radioactive decay of actinides (mainly U) in zircon is a principal factor that is responsible for the spectral variations. Radiation damage (metamictization) is probably a common phenomenon among microdiamonds in zircon in diamond-bearing rocks from the Kokchetav Massif (c.f., Shimizu & Ogasawara, 2011; Smith et al., 2011). To discuss the genesis of diamond from its Raman, PL or CL spectra, microdiamonds contained in actinides-bearing minerals (e.g., zircon) should be treated with the most careful attention because radiation damage after the formation does influence the spectra significantly.

  6. Alterations of domains in the plasmatic membrane due to damages of the perinuclear theca of pig preserved spermatozoa.

    PubMed

    Orozco Benítez, María Guadalupe; Lemus Flores, Clemente; Hernández Ballesteros, Juan Antonio; Navarrete Méndez, Raúl; Juárez-Mosqueda, María de Lourdes

    2008-05-15

    Samples of semen from 12 pigs, three from Yorkshire, Landrace, Duroc and Mexican Hairless each where obtained to study cryopreservation methods. Three stages of boar semen cryopreservation were evaluated: none (fresh stage), cooling at 5 degrees C and freezing at -196 degrees C then thawing to 56 degrees C for 12 sec. Perinuclear theca damage and domain alterations were selected as indices of seminal quality, as measured by electronic and fluorescence microcopy, respectively according to two lineal models considering by separately the effect of semen preservation and breed. Integrity and absence of perinuclear theca significantly (p < 0.001) decreased and increased, respectively according to a decrease in temperature of cryopreservation, from 87.4 to 58.8% and from 0.8 to 26.2%, respectively. This same significant (p < 0.001) effect was found for acrosomal and post-acrosomal membrane distribution of domains, from 92.1 to 76.8% and from 3.1 to 13.1% in this same order. Slight but highly significant (p < 0.001) differences were observed when theca integrity was evaluated as affected by breed, with highest and lowest values for Yorkshire and Pel6n Mexicano pigs, respectively. No breed effect was encountered for presence of acrosomal domains. A strong interdependence was found between perinuclear theca damage and domain distribution. In this connection, a highly significant (p < 0.001) positive, interdependence was observed between the theca damage and acrosomal domain (r = 0.87), while this same relationship was although highly significant (p < 0.001), negative in nature for equatorial and post-acrosonal domains (r = -0.77 and -0.85, respectively). This experiment confirmed that cryopreservation methods may severely affect semen quality of pigs and that genotype may further influence these same indices. More research is needed for improving methods of preservation of pig semen quality, from the point of view of perinuclear theca and domain characteristics of

  7. Two-dimensional nonlinear finite element analysis of well damage due to reservoir compaction, well-to-well interactions, and localization on weak layers

    SciTech Connect

    Hilbert, L.B. Jr.; Fredrich, J.T.; Bruno, M.S.; Deitrick, G.L.; Rouffignac, E.P. de

    1996-05-01

    In this paper the authors present the results of a coupled nonlinear finite element geomechanics model for reservoir compaction and well-to-well interactions for the high-porosity, low strength diatomite reservoirs of the Belridge field near Bakersfield, California. They show that well damage and failures can occur under the action of two distinct mechanisms: shear deformations induced by pore compaction, and subsidence, and shear deformations due to well-to-well interactions during production or water injection. They show such casting damage or failure can be localized to weak layers that slide or slip under shear due to subsidence. The magnitude of shear displacements and surface subsidence agree with field observations.

  8. Formation of lithospheric shear zones: Effect of temperature on two-phase grain damage

    NASA Astrophysics Data System (ADS)

    Mulyukova, Elvira; Bercovici, David

    2017-09-01

    Shear localization in the lithosphere is a characteristic feature of plate tectonic boundaries, and is evident in the presence of small grain mylonites. Localization and mylonitization in the ductile portion of the lithosphere can arise when its polymineralic material deforms by a grain-size sensitive rheology in combination with Zener pinning, which can impede, or possibly even reverse, grain growth and thus promotes a self-softening feedback mechanism. However, the efficacy of this mechanism is not ubiquitous and depends on lithospheric conditions such as temperature and stress. Therefore, we explore the conditions under which self-weakening takes place, and, in particular, the effect of temperature and deformation state (stress or strain-rate) on these conditions. In our model, the lithosphere-like polymineralic material is deformed in a two-dimensional simple shear driven by constant stress or strain rate. The mineral grains evolve to a stable size, which is obtained when the rate of coarsening by normal grain growth and the rate of grain size reduction by damage are in balance. Damage involves processes by which some of the deformational energy gets transferred into surface energy. This can happen by (i) dynamic recrystallization (grain damage) and (ii) stretching, deforming and stirring the material interface (interface damage). The influence of temperature enters through rheological laws (which govern the rate of work and damage), grain growth kinetics, and the damage partitioning fraction, which is the fraction of deformational work that goes into creating new surface energy. We demonstrate that a two-phase damage model, in which the partitioning fraction depends on both temperature and roughness of the interface between the phases, can successfully match the field data, including the reported correlation of grain size and temperature, the increasing dominance of dislocation creep at higher temperatures and a large range of grain sizes observed across the

  9. Extent, perception and mitigation of damage due to high groundwater levels in the city of Dresden, Germany

    NASA Astrophysics Data System (ADS)

    Kreibich, H.; Thieken, A. H.; Grunenberg, H.; Ullrich, K.; Sommer, T.

    2009-07-01

    Flood risk analysis and management plans mostly neglect groundwater flooding, i.e. high groundwater levels. However, rising groundwater may cause considerable damage to buildings and infrastructure. To improve the knowledge about groundwater flooding and support risk management, a survey was undertaken in the city of Dresden (Saxony, Germany), resulting in 605 completed interviews with private households endangered by high groundwater levels. The reported relatively low flood impact and damage of groundwater floods in comparison with mixed floods was reflected by its scarce perception: Hardly anybody thinks about the risk of groundwater flooding. The interviewees thought that public authorities and not themselves, should be mainly responsible for preparedness and emergency response. Up to now, people do not include groundwater risk in their decision processes on self protection. The implementation of precautionary measures does not differ between households with groundwater or with mixed flood experience. However, less households undertake emergency measures when expecting a groundwater flood only. The state of preparedness should be further improved via an intensified risk communication about groundwater flooding by the authorities. Conditions to reach the endangered population are good, since 70% of the interviewed people are willing to inform themselves about groundwater floods. Recommendations for an improved risk communication are given.

  10. Repair of UVB-induced DNA damage is reduced in melanoma due to low XPC and global genome repair

    PubMed Central

    Budden, Timothy; Davey, Ryan J.; Vilain, Ricardo E.; Ashton, Katie A.; Braye, Stephen G.; Beveridge, Natalie J.; Bowden, Nikola A.

    2016-01-01

    UVB exposure leads to DNA damage, which when unrepaired induces C>T transitions. These mutations are found throughout the melanoma genome, particularly in non-transcribed regions. The global genome repair (GGR) branch of nucleotide excision repair (NER) is responsible for repairing UV-induced DNA damage across non-transcribed and silent regions of the genome. This study aimed to examine the relationship between UVB and GGR in melanoma. DNA repair capacity and relative expression of NER in melanocytes and melanoma cell lines before and after treatment with UVB was quantified. Transcript expression from 196 melanomas was compared to clinical parameters including solar elastosis and whole transcriptome data collected. Melanoma cell lines showed significantly reduced DNA repair when compared to melanocytes, most significantly in the S phase of the cell cycle. Expression of GGR components XPC, DDB1 and DDB2 was significantly lower in melanoma after UVB. In the melanoma tumours, XPC expression correlated with age of diagnosis and low XPC conferred significantly poorer survival. The same trend was seen in the TCGA melanoma dataset. Reduced GGR in melanoma may contribute to the UV mutation spectrum of the melanoma genome and adds further to the growing evidence of the link between UV, NER and melanoma. PMID:27487145

  11. Investigations of Pulmonary Epithelial Cell Damage due to Air-Liquid Interfacial Stresses in a Microgravity Environment

    NASA Technical Reports Server (NTRS)

    Gaver, Donald P., III; Bilek, A. M.; Kay, S.; Dee, K. C.

    2004-01-01

    Pulmonary airway closure is a potentially dangerous event that can occur in microgravity environments and may result in limited gas exchange for flight crew during long-term space flight. Repetitive airway collapse and reopening subjects the pulmonary epithelium to large, dynamic, and potentially injurious mechanical stresses. During ventilation at low lung volumes and pressures, airway instability leads to repetitive collapse and reopening. During reopening, air must progress through a collapsed airway, generating stresses on the airway walls, potentially damaging airway tissues. The normal lung can tolerate repetitive collapse and reopening. However, combined with insufficient or dysfunctional pulmonary surfactant, repetitive airway collapse and reopening produces severe lung injury. Particularly at risk is the pulmonary epithelium. As an important regulator of lung function and physiology, the degree of pulmonary epithelial damage influences the course and outcome of lung injury. In this paper we present experimental and computational studies to explore the hypothesis that the mechanical stresses associated with airway reopening inflict injury to the pulmonary epithelium.

  12. Aldh2 knockout mice were more sensitive to DNA damage in leukocytes due to ethyl tertiary butyl ether exposure.

    PubMed

    Weng, Zuquan; Suda, Megumi; Ohtani, Katsumi; Mei, Nan; Kawamoto, Toshihiro; Nakajima, Tamie; Wang, Rui-Sheng

    2011-01-01

    To clarify the genotoxicity of ethyl tertiary butyl ether (ETBE), a gasoline additive, male and female C57BL/6 mice of Aldh2+/+ and Aldh2-/- genotypes, aged 8 wk, were exposed to 0, 500, 1,750, or 5,000 ppm ETBE for 6 h/day, 5 d per week for 13 wk. DNA damage in leukocytes was measured by the alkaline comet assay and expressed quantitatively as Tail Intensity (TI). For male mice, TI was significantly higher in all three groups exposed to ETBE than in those without exposure within Aldh2-/- mice, whereas within Aldh2+/+ mice, TI increased only in those exposed to 5,000 ppm of ETBE as compared with mice without exposure. For female mice, a significant increase in TI values was observed in the group exposed to 5,000 ppm of ETBE as compared with those without exposure within Aldh2-/- mice; TI in Aldh2-/- mice exposed to 1,750 and 5,000 ppm was significantly higher than in Aldh2+/+ mice without exposure. TI did not significantly increase in any of the groups exposed to ETBE within female Aldh2+/+ mice. Based on the results we suggest that Aldh2-/- mice are more sensitive to DNA damage caused by ETBE than Aldh2+/+ mice and that males seem more susceptible to this effect than females.

  13. Protective effects of melatonin and vitamin E in brain damage due to gamma radiation: an experimental study.

    PubMed

    Erol, Fatih S; Topsakal, Cahide; Ozveren, M Faik; Kaplan, Metin; Ilhan, Nevin; Ozercan, I Hanifi; Yildiz, Oguz G

    2004-01-01

    Gamma radiation is known to cause serious damage in the brain, and many agents have been used for neuroprotection. In this study, lipid peroxidation levels and histopathological changes in brain tissues of whole-body irradiated rats with likely radiation injury were compared to those with melatonin and vitamin E protection. Forty rats in four equal groups were used. The control group received neither radiation nor medication. The remaining groups received doses of 720 cGy in two equal fractions 12 h apart. The second group received radiation but no medication, the third received radiation plus 100 mg/kg per day of vitamin E i.p., and the fourth received radiation plus 100 mg/kg per day of melatonin i.p. over 5 days. On the 10th postoperative day, all the rats were decapitated and specimens from parietal cortices were analyzed for tissue malondialdehyde (MDA) levels and histopathological changes. Increases in MDA were relatively well prevented by melatonin treatment but less so with vitamin E therapy. On histopathological examination, melatonin significantly reduced the rates of edema, necrosis, and neuronal degeneration, whereas vitamin E reduced only necrosis. Neither substance was capable of preventing vasodilatation. In conclusion, melatonin may be useful in preventing the pathological changes of secondary brain damage as a result of free oxygen radicals generated by irradiation.

  14. Retinal Afferent Ingrowth to Neocortical Transplants in the Adult Rat Superior Colliculus is due to the Regeneration of Damaged Axons

    PubMed Central

    Ross, D. T.; Das, G. D.

    1994-01-01

    Retinal afferent ingrowth to embryonic neural transplants in the adult rat superior colliculus may represent either sprouting of intact axons or the regeneration of transected axons. If ingrowth represents regeneration of damaged retinofugai axons, then lesions that axotomize more retinofugal axons at the transplantation site should induce greater retinal afferent ingrowth. Alternately, if ingrowth represents terminal or collateral sprouting of intact retinofugal axons at or near the transplant/host optic layer interface, then the magnitude of retinal afferent ingrowth should be directly related to the total area of this interface. To test between these two hypotheses surgical knife wounds were made either parallel (in the sagittal plane) or perpendicular (in the transverse plane) to the course of axons in the stratum opticum, embryonic neocortical tissue was transplanted at the coordinates of these tectal slits, and retinal afferent ingrowth visualized 1-90 days after surgery using anterogradely transported HRP. A zone of traumatic reaction (ztr) in the optic layers was seen in every case, characterized by hypertrophied axons and swollen terminal clubs at 1 day. Between 30 and 90 days the damaged retinofugal axons in the zone formed dense fascicles and neuroma-like tangles. Retinal afferent ingrowth occurred only across transplant interface regions with the ztr. The magnitude of ingrowth was directly related to the area of the ztr interface and not the total optic layer interface area. Retinal afferent ingrowth appears to reflect the intrinsic regenerative capacity of adult mammalian retinal ganglion cells and not sprouting of undamaged axons. PMID:7703292

  15. Loss of transmittance in fluoropolymer films due to laser-induced damage at 1053 and 351-nm

    SciTech Connect

    Whitman, P.; Milam, D.; Norton, M.; Sell, W.

    1997-12-01

    Thick fluoropolymer films are being evaluated as a potential `disposable` debris shield to protect high-peak-power laser optics from x-ray and target debris generated in inertial-confinement fusion-ignition experiments, Two obstacles to implementation are optical uniformity and damage threshold. To understand the damage characteristics, transmittance of single 1053- or 351-nm laser pulses has been measured for commercial fluoropolymer films in vacuum. Samples were tested at fluences up to 105 J/cm2 at 1053-nm and 13 J/cm2 at 351-nm. Both the total transmitted energy for a single shot and the temporal energy transmittance profile during the shot were measured as a function of fluence. In addition, the total focusable transmitted energy was recorded for 351 -nm pulses. Results show that transmittance decreases slowly during a single-pulse irradiation, allowing much of the energy to be transmitted at fluences which cause noticeable degradation to the film. The film transmits greater than 90% of the 351-nm energy delivered in a beam with spatial average fluence of 8 J/cm2 with modulation up to 15 J/cm2. For 1053-nm laser light, the films do not begin to exhibit noticeable transmittance loss until average fluences exceed 40 J/cm2.

  16. Blob Formation and Ejection in Coronal Jets due to the Plasmoid and Kelvin-Helmholtz Instabilities

    NASA Astrophysics Data System (ADS)

    Ni, Lei; Zhang, Qing-Min; Murphy, Nicholas A.; Lin, Jun

    2017-05-01

    We perform 2D resistive magnetohydrodynamic simulations of coronal jets driven by flux emergence along the lower boundary. The reconnection layers are susceptible to the formation of blobs that are ejected in the jet. Our simulation with low plasma β (Case I) shows that magnetic islands form easily and propagate upward in the jet. These islands are multithermal and thus are predicted to show up in hot channels (335 Å and 211 Å) and the cool channel (304 Å) in observations by the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory. The islands have maximum temperatures of 8 MK, lifetimes of 120 s, diameters of 6 Mm, and velocities of 200 km s-1. These parameters are similar to the properties of blobs observed in extreme-ultraviolet (EUV) jets by AIA. The Kelvin-Helmholtz instability develops in our simulation with moderately high plasma β (Case II) and leads to the formation of bright vortex-like blobs above the multiple high magnetosonic Mach number regions that appear along the jet. These vortex-like blobs can also be identified in the AIA channels. However, they eventually move downward and disappear after the high magnetosonic Mach number regions disappear. In the lower plasma β case, the lifetime for the jet is shorter, the jet and magnetic islands are formed with higher velocities and temperatures, the current-sheet fragments are more chaotic, and more magnetic islands are generated. Our results show that the plasmoid instability and Kelvin-Helmholtz instability along the jet are both possible causes of the formation of blobs observed at EUV wavelengths.

  17. Equatorial disk formation around rotating stars due to ram pressure confinement by the stellar wind

    NASA Technical Reports Server (NTRS)

    Bjorkman, J. E.; Cassinelli, J. P.

    1993-01-01

    The axisymmetric 2D supersonic solution of a rotating, radiation-driven stellar wind presently obtained by a simple approximation predicts the formation of a dense equatorial disk, when the star's rotation rate lies above a threshold value that depends on the ratio of the wind's terminal speed to the escape speed of the star. The disk is formed because the trajectories of the wind leaving the stellar surface at high latitudes carry it down to the equatorial plane; there, the material passes through a standing oblique shock atop the disk; it is therefore the ram pressure of the polar wind that compresses and confines the disk.

  18. Anhelation due to formation of tuberculomas at the medulla oblongata during chemotherapy of tuberculous meningitis.

    PubMed

    Ge, Pengfei; Zhang, Xiaojie; Zhong, Yangping; Bian, Xinchao; Fu, Shuanglin; Luo, Yinan

    2012-01-01

    Formation of tuberculoma is a rare response of neurotuberculosis in patients regularly and adequately treated with anti-tuberculous drugs. We report a 13-year-old girl with two tuberculomas which formed in the dorsal part of the medulla oblongata during chemotherapy for tuberculous meningitis. The tuberculomas were both removed via a suboccipital midline approach and were demonstrated by pathological findings but the girl died of cardiac arrest that was thought to be caused by postoperative medulla oblongata oedema. In combination with a literature review, we discuss the clinical features and treatment options of brainstem tuberculomas.

  19. Acceleration of raindrop formation due to the tangling-clustering instability in a turbulent stratified atmosphere

    NASA Astrophysics Data System (ADS)

    Elperin, T.; Kleeorin, N.; Krasovitov, B.; Kulmala, M.; Liberman, M.; Rogachevskii, I.; Zilitinkevich, S.

    2015-07-01

    Condensation of water vapor on active cloud condensation nuclei produces micron-size water droplets. To form rain, they must grow rapidly into at least 50- to 100 -μ m droplets. Observations show that this process takes only 15-20 min. The unexplained physical mechanism of such fast growth is crucial for understanding and modeling of rain and known as "condensation-coalescence bottleneck in rain formation." We show that the recently discovered phenomenon of the tangling clustering instability of small droplets in temperature-stratified turbulence [Phys. Fluids 25, 085104 (2013), 10.1063/1.4816643] results in the formation of droplet clusters with drastically increased droplet number densities. The mechanism of the tangling clustering instability is much more effective than the previously considered by us the inertial clustering instability caused by the centrifugal effect of turbulent vortices. This is the reason of strong enhancement of the collision-coalescence rate inside the clusters. The mean-field theory of the droplet growth developed in this study can be useful for explanation of the observed fast growth of cloud droplets in warm clouds from the initial 1 -μ m -size droplets to 40- to 50 -μ m -size droplets within 15-20 min.

  20. Conduction Channel Formation and Dissolution Due to Oxygen Thermophoresis/Diffusion in Hafnium Oxide Memristors.

    PubMed

    Kumar, Suhas; Wang, Ziwen; Huang, Xiaopeng; Kumari, Niru; Davila, Noraica; Strachan, John Paul; Vine, David; Kilcoyne, A L David; Nishi, Yoshio; Williams, R Stanley

    2016-12-27

    Transition-metal-oxide memristors, or resistive random-access memory (RRAM) switches, are under intense development for storage-class memory because of their favorable operating power, endurance, speed, and density. Their commercial deployment critically depends on predictive compact models based on understanding nanoscale physicochemical forces, which remains elusive and controversial owing to the difficulties in directly observing atomic motions during resistive switching, Here, using scanning transmission synchrotron X-ray spectromicroscopy to study in situ switching of hafnium oxide memristors, we directly observed the formation of a localized oxygen-deficiency-derived conductive channel surrounded by a low-conductivity ring of excess oxygen. Subsequent thermal annealing homogenized the segregated oxygen, resetting the cells toward their as-grown resistance state. We show that the formation and dissolution of the conduction channel are successfully modeled by radial thermophoresis and Fick diffusion of oxygen atoms driven by Joule heating. This confirmation and quantification of two opposing nanoscale radial forces that affect bipolar memristor switching are important components for any future physics-based compact model for the electronic switching of these devices.

  1. Ionic liquid effects on a multistep process. Increased product formation due to enhancement of all steps.

    PubMed

    Keaveney, Sinead T; Haines, Ronald S; Harper, Jason B

    2015-09-07

    The reaction of a series of substituted benzaldehydes with hexylamine was examined in acetonitrile and an ionic liquid. In acetonitrile, as the electron withdrawing nature of the substituent increases, the overall addition-elimination process becomes faster as does the build-up of the aminol intermediate. Under equivalent conditions in an ionic liquid, less intermediate build up is observed, and the effect on the rate on varying the substituent is different to that in acetonitrile. Extensive kinetic analysis shows that the ionic liquid solvent increases the rate constant of all steps of the reaction, resulting in faster product formation relative to acetonitrile; these effects increase with the proportion of ionic liquid in the reaction mixture. Differences in the equilibrium position of the addition step in the ionic liquid were found to account for both the decrease in intermediate build up relative to acetonitrile, as well as the differing trend in the overall rate of product formation as the substituent was changed. The microscopic origins of these ionic liquid effects were probed through temperature dependent analyses, highlighting the subtle balance of interactions between the ionic liquid and species along the reaction coordinate, particularly the importance of charge development in the transition state.

  2. Extended asymmetric hot region formation due to shockwave interactions following void collapse in shocked high explosive

    SciTech Connect

    Shan, Tzu -Ray; Wixom, Ryan R.; Thompson, Aidan P.

    2016-08-01

    In both continuum hydrodynamics simulations and also multimillion atom reactive molecular dynamics simulations of shockwave propagation in single crystal pentaerythritol tetranitrate (PETN) containing a cylindrical void, we observed the formation of an initial radially symmetric hot spot. By extending the simulation time to the nanosecond scale, however, we observed the transformation of the small symmetric hot spot into a longitudinally asymmetric hot region extending over a much larger volume. Performing reactive molecular dynamics shock simulations using the reactive force field (ReaxFF) as implemented in the LAMMPS molecular dynamics package, we showed that the longitudinally asymmetric hot region was formed by coalescence of the primary radially symmetric hot spot with a secondary triangular hot zone. We showed that the triangular hot zone coincided with a double-shocked region where the primary planar shockwave was overtaken by a secondary cylindrical shockwave. The secondary cylindrical shockwave originated in void collapse after the primary planar shockwave had passed over the void. A similar phenomenon was observed in continuum hydrodynamics shock simulations using the CTH hydrodynamics package. Furthermore, the formation and growth of extended asymmetric hot regions on nanosecond timescales has important implications for shock initiation thresholds in energetic materials.

  3. Methemoglobin and sulfhemoglobin formation due to benzocaine and lidocaine in macaques

    SciTech Connect

    Martin, D.G.; Woodard, C.L.; Gold, M.B.; Watson, C.E.; Baskin, S.I.

    1993-05-13

    Benzocaine (BNZ) and lidocaine (LC) are commonly used topical (spray) anesthetics approved for use in humans. BNZ has structural similarities to methemoglobin (MHb) forming drugs that are current candidates for cyanide prophylaxis, while LC has been reported to increase MHb in man. We therefore, compared MHb and sulfhemoglobin (SHb) production in three groups of Macaques (Macaca mulata, Chinese rhesus and Indian rhesus, and Macaca nemistrina, Pig-tailed Macaques) after exposure to BNZ and LC. Formation of SHb, unlike MHb, is not thought to be reversible and is considered to be toxic. MHb and SHb levels were measured periodically on a CO-Oximeter. All rhesus (n=8) were dosed intratrachealy/intranasaly with 56 mg and 280 mg BNZ and with 40 mg of LC in a randomized cross-over design. Pig-tailed macaques (n=6) were dosed with BNZ intranasaly 56 mg and with 40 mg of LC. Since no differences in the peak MHb or time to peak (mean +/- SD) were observed among the three macaque subspecies, the data were pooled. LC did not cause MHb or SHb formation above baseline in any monkey.

  4. Extended asymmetric hot region formation due to shockwave interactions following void collapse in shocked high explosive

    DOE PAGES

    Shan, Tzu -Ray; Wixom, Ryan R.; Thompson, Aidan P.

    2016-08-01

    In both continuum hydrodynamics simulations and also multimillion atom reactive molecular dynamics simulations of shockwave propagation in single crystal pentaerythritol tetranitrate (PETN) containing a cylindrical void, we observed the formation of an initial radially symmetric hot spot. By extending the simulation time to the nanosecond scale, however, we observed the transformation of the small symmetric hot spot into a longitudinally asymmetric hot region extending over a much larger volume. Performing reactive molecular dynamics shock simulations using the reactive force field (ReaxFF) as implemented in the LAMMPS molecular dynamics package, we showed that the longitudinally asymmetric hot region was formed bymore » coalescence of the primary radially symmetric hot spot with a secondary triangular hot zone. We showed that the triangular hot zone coincided with a double-shocked region where the primary planar shockwave was overtaken by a secondary cylindrical shockwave. The secondary cylindrical shockwave originated in void collapse after the primary planar shockwave had passed over the void. A similar phenomenon was observed in continuum hydrodynamics shock simulations using the CTH hydrodynamics package. Furthermore, the formation and growth of extended asymmetric hot regions on nanosecond timescales has important implications for shock initiation thresholds in energetic materials.« less

  5. Extended asymmetric hot region formation due to shockwave interactions following void collapse in shocked high explosive

    SciTech Connect

    Shan, Tzu -Ray; Wixom, Ryan R.; Thompson, Aidan P.

    2016-08-01

    In both continuum hydrodynamics simulations and also multimillion atom reactive molecular dynamics simulations of shockwave propagation in single crystal pentaerythritol tetranitrate (PETN) containing a cylindrical void, we observed the formation of an initial radially symmetric hot spot. By extending the simulation time to the nanosecond scale, however, we observed the transformation of the small symmetric hot spot into a longitudinally asymmetric hot region extending over a much larger volume. Performing reactive molecular dynamics shock simulations using the reactive force field (ReaxFF) as implemented in the LAMMPS molecular dynamics package, we showed that the longitudinally asymmetric hot region was formed by coalescence of the primary radially symmetric hot spot with a secondary triangular hot zone. We showed that the triangular hot zone coincided with a double-shocked region where the primary planar shockwave was overtaken by a secondary cylindrical shockwave. The secondary cylindrical shockwave originated in void collapse after the primary planar shockwave had passed over the void. A similar phenomenon was observed in continuum hydrodynamics shock simulations using the CTH hydrodynamics package. Furthermore, the formation and growth of extended asymmetric hot regions on nanosecond timescales has important implications for shock initiation thresholds in energetic materials.

  6. Extended asymmetric hot region formation due to shockwave interactions following void collapse in shocked high explosive

    NASA Astrophysics Data System (ADS)

    Shan, Tzu-Ray; Wixom, Ryan R.; Thompson, Aidan P.

    2016-08-01

    In both continuum hydrodynamics simulations and also multimillion atom reactive molecular dynamics simulations of shockwave propagation in single crystal pentaerythritol tetranitrate (PETN) containing a cylindrical void, we observed the formation of an initial radially symmetric hot spot. By extending the simulation time to the nanosecond scale, however, we observed the transformation of the small symmetric hot spot into a longitudinally asymmetric hot region extending over a much larger volume. Performing reactive molecular dynamics shock simulations using the reactive force field (ReaxFF) as implemented in the LAMMPS molecular dynamics package, we showed that the longitudinally asymmetric hot region was formed by coalescence of the primary radially symmetric hot spot with a secondary triangular hot zone. We showed that the triangular hot zone coincided with a double-shocked region where the primary planar shockwave was overtaken by a secondary cylindrical shockwave. The secondary cylindrical shockwave originated in void collapse after the primary planar shockwave had passed over the void. A similar phenomenon was observed in continuum hydrodynamics shock simulations using the CTH hydrodynamics package. The formation and growth of extended asymmetric hot regions on nanosecond timescales has important implications for shock initiation thresholds in energetic materials.

  7. Acceleration of raindrop formation due to the tangling-clustering instability in a turbulent stratified atmosphere.

    PubMed

    Elperin, T; Kleeorin, N; Krasovitov, B; Kulmala, M; Liberman, M; Rogachevskii, I; Zilitinkevich, S

    2015-07-01

    Condensation of water vapor on active cloud condensation nuclei produces micron-size water droplets. To form rain, they must grow rapidly into at least 50- to 100-μm droplets. Observations show that this process takes only 15-20 min. The unexplained physical mechanism of such fast growth is crucial for understanding and modeling of rain and known as "condensation-coalescence bottleneck in rain formation." We show that the recently discovered phenomenon of the tangling clustering instability of small droplets in temperature-stratified turbulence [Phys. Fluids 25, 085104 (2013)] results in the formation of droplet clusters with drastically increased droplet number densities. The mechanism of the tangling clustering instability is much more effective than the previously considered by us the inertial clustering instability caused by the centrifugal effect of turbulent vortices. This is the reason of strong enhancement of the collision-coalescence rate inside the clusters. The mean-field theory of the droplet growth developed in this study can be useful for explanation of the observed fast growth of cloud droplets in warm clouds from the initial 1-μm-size droplets to 40- to 50-μm-size droplets within 15-20 min.

  8. Early amygdala or hippocampus damage influences adolescent female social behavior during group formation.

    PubMed

    Moadab, Gilda; Bliss-Moreau, Eliza; Bauman, Melissa D; Amaral, David G

    2017-02-01

    This study continues a longitudinal analysis of rhesus macaque social behavior following bilateral neonatal ibotenic acid lesions of the amygdala or hippocampus, or sham operations. The social behavior of female subjects was evaluated at a critical developmental time point-the transition to adulthood. At approximately 4 years of age, female subjects were housed in small groups with other female subjects and reproductively viable adult males. As compared with neurologically intact control animals and animals with early amygdala damage, animals with early hippocampal damage were more social with their female peers. In contrast, as compared with control animals, animals with early amygdala damage spent less time with the males, engaged less frequently in behaviors typical of reproductive consortships, had higher frequencies of self-directed stereotypies, and became pregnant later. Males also generated fewer communicative signals toward animals with early amygdala damage than to control animals and animals with early hippocampus damage. Rates of sexual behavior were generally low for all animals, and there were no lesion-based differences in their frequencies. Discriminant function analyses demonstrated that patterns of affiliative social behaviors differed across the 3 experimental groups, both in terms of the social behaviors directed to the males, and the social behaviors generated by the males toward the females. In 4 of the 5 social groups, amygdala-lesioned animals were lowest ranked, potentially contributing to reduced sociability interactions with males. Other potential mechanisms and the experiments needed to elucidate them are discussed. (PsycINFO Database Record

  9. Phosphoramide mustard exposure induces DNA adduct formation and the DNA damage repair response in rat ovarian granulosa cells.

    PubMed

    Ganesan, Shanthi; Keating, Aileen F

    2015-02-01

    Phosphoramide mustard (PM), the ovotoxic metabolite of the anti-cancer agent cyclophosphamide (CPA), destroys rapidly dividing cells by forming NOR-G-OH, NOR-G and G-NOR-G adducts with DNA, potentially leading to DNA damage. A previous study demonstrated that PM induces ovarian DNA damage in rat ovaries. To investigate whether PM induces DNA adduct formation, DNA damage and induction of the DNA repair response, rat spontaneously immortalized granulosa cells (SIGCs) were treated with vehicle control (1% DMSO) or PM (3 or 6μM) for 24 or 48h. Cell viability was reduced (P<0.05) after 48h of exposure to 3 or 6μM PM. The NOR-G-OH DNA adduct was detected after 24h of 6μM PM exposure, while the more cytotoxic G-NOR-G DNA adduct was formed after 48h by exposure to both PM concentrations. Phosphorylated H2AX (γH2AX), a marker of DNA double stranded break occurrence, was also increased by PM exposure, coincident with DNA adduct formation. Additionally, induction of genes (Atm, Parp1, Prkdc, Xrcc6, and Brca1) and proteins (ATM, γH2AX, PARP-1, PRKDC, XRCC6, and BRCA1) involved in DNA repair were observed in both a time- and dose-dependent manner. These data support that PM induces DNA adduct formation in ovarian granulosa cells, induces DNA damage and elicits the ovarian DNA repair response. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Causes and circumstances of damage to people in Calabria (Italy) due to hydrogeological events in the period 1980-2014

    NASA Astrophysics Data System (ADS)

    Aceto, Luigi; Pasqua, A. Aurora; Petrucci, Olga

    2017-04-01

    Damaging Hydrogeological Events (DHE) can be defined as rainy periods during which landslides and floods can damage people. We investigates the effects of DHE on people in Calabria (southern Italy) ,in the period 1980-2014, using data coming from the systematic survey of regional daily newspapers. Data about "fatalities", people "injured" and people "involved" (not killed neither hurt) are stored in the database named PEOPLE, made of five sections: 1) event identification, 2) victim identification, 3) type of victim's involvement, 4) victim-event interaction, and 5) effects on victim. The outcomes highlight vulnerability factors related to gender and age: males were killed more frequently (75%) than females (25%), and fatalities were older (average age 49 years) than injured (40.1 years) and involved people (40.5 years). The average age of females killed (67.5 years), injured (43.4 years) and involved (44.6 years) were higher than the same values assessed for males, maybe indicating that younger females tend to be more cautious than coetaneous males, while older females show an intrinsic greater vulnerability. Involved people were younger than injured and fatalities, perhaps because younger people showed greater promptness to react in dangerous situations. In the study region, floods caused more fatalities (67.9%), injured (55%) and involved people (55.3%) than landslides. Fatalities and injured mainly occurred outdoor, especially along roads, and the most dangerous dynamic seems to be dragged by flood, causing the majority of fatalities. The present work is the progression of the described research, and it has been carried out by enlarging the database to a 34-year period, from 1980 to 2014. The aim is to validate the conclusions drawn for the 2000-2014 period and to investigate if and how the gender and age vulnerability factors of Calabrian people have been changing throughout the study period.

  11. An assessment of the resolution limitation due to radiation-damage in X-ray diffraction microscopy

    DOE PAGES

    Howells, M. R.; Beetz, T.; Chapman, H. N.; ...

    2008-11-17

    X-ray diffraction microscopy (XDM) is a new form of x-ray imaging that is being practiced at several third-generation synchrotron-radiation x-ray facilities. Nine years have elapsed since the technique was first introduced and it has made rapid progress in demonstrating high-resolution three-dimensional imaging and promises few-nm resolution with much larger samples than can be imaged in the transmission electron microscope. Both life- and materials-science applications of XDM are intended, and it is expected that the principal limitation to resolution will be radiation damage for life science and the coherent power of available x-ray sources for material science. In this paper wemore » address the question of the role of radiation damage. We use a statistical analysis based on the so-called "dose fractionation theorem" of Hegerl and Hoppe to calculate the dose needed to make an image of a single life-science sample by XDM with a given resolution. We find that for simply-shaped objects the needed dose scales with the inverse fourth power of the resolution and present experimental evidence to support this finding. To determine the maximum tolerable dose we have assembled a number of data taken from the literature plus some measurements of our own which cover ranges of resolution that are not well covered otherwise. The conclusion of this study is that, based on the natural contrast between protein and water and "Rose-criterion" image quality, one should be able to image a frozen-hydrated biological sample using XDM at a resolution of about 10 nm.« less

  12. An assessment of the resolution limitation due to radiation-damage in x-ray diffraction microscopy

    PubMed Central

    Howells, M. R.; Beetz, T.; Chapman, H. N.; Cui, C.; Holton, J. M.; Jacobsen, C. J.; Kirz, J.; Lima, E.; Marchesini, S.; Miao, H.; Sayre, D.; Shapiro, D. A.; Spence, J. C. H.; Starodub, D.

    2010-01-01

    X-ray diffraction microscopy (XDM) is a new form of x-ray imaging that is being practiced at several third-generation synchrotron-radiation x-ray facilities. Nine years have elapsed since the technique was first introduced and it has made rapid progress in demonstrating high-resolution three-dimensional imaging and promises few-nm resolution with much larger samples than can be imaged in the transmission electron microscope. Both life- and materials-science applications of XDM are intended, and it is expected that the principal limitation to resolution will be radiation damage for life science and the coherent power of available x-ray sources for material science. In this paper we address the question of the role of radiation damage. We use a statistical analysis based on the so-called “dose fractionation theorem” of Hegerl and Hoppe to calculate the dose needed to make an image of a single life-science sample by XDM with a given resolution. We find that for simply-shaped objects the needed dose scales with the inverse fourth power of the resolution and present experimental evidence to support this finding. To determine the maximum tolerable dose we have assembled a number of data taken from the literature plus some measurements of our own which cover ranges of resolution that are not well covered otherwise. The conclusion of this study is that, based on the natural contrast between protein and water and “Rose-criterion” image quality, one should be able to image a frozen-hydrated biological sample using XDM at a resolution of about 10 nm. PMID:20463854

  13. An assessment of the resolution limitation due to radiation-damage in X-ray diffraction microscopy

    SciTech Connect

    Howells, M. R.; Beetz, T.; Chapman, H. N.; Cui, C.; Holton, J. M.; Jacobsen, C. J.; Kirz, J.; Lima, E.; Marchesini, S.; Miao, H.; Sayre, D.; Shapiro, D. A.; Spence, J. C.H.; Starodub, D.

    2008-11-17

    X-ray diffraction microscopy (XDM) is a new form of x-ray imaging that is being practiced at several third-generation synchrotron-radiation x-ray facilities. Nine years have elapsed since the technique was first introduced and it has made rapid progress in demonstrating high-resolution three-dimensional imaging and promises few-nm resolution with much larger samples than can be imaged in the transmission electron microscope. Both life- and materials-science applications of XDM are intended, and it is expected that the principal limitation to resolution will be radiation damage for life science and the coherent power of available x-ray sources for material science. In this paper we address the question of the role of radiation damage. We use a statistical analysis based on the so-called "dose fractionation theorem" of Hegerl and Hoppe to calculate the dose needed to make an image of a single life-science sample by XDM with a given resolution. We find that for simply-shaped objects the needed dose scales with the inverse fourth power of the resolution and present experimental evidence to support this finding. To determine the maximum tolerable dose we have assembled a number of data taken from the literature plus some measurements of our own which cover ranges of resolution that are not well covered otherwise. The conclusion of this study is that, based on the natural contrast between protein and water and "Rose-criterion" image quality, one should be able to image a frozen-hydrated biological sample using XDM at a resolution of about 10 nm.

  14. Scenario-based assessment of buildings damage and population exposure due to tsunamis for the town of Alexandria, Egypt

    NASA Astrophysics Data System (ADS)

    Pagnoni, G.; Armigliato, A.; Tinti, S.

    2015-08-01

    Alexandria is the second biggest city in Egypt as regards population, is a key economic area in northern Africa and has a very important tourist activity. Historical catalogues indicate that it was severely affected by a number of tsunami events. In this work we assess the tsunami hazard by running numerical simulations of tsunami impact in Alexandria through the Worst-case Credible Tsunami Scenario Analysis (WCTSA). We identify three main seismic sources: the Western Hellenic Arc (WHA - reference event AD 365, Mw = 8.5), the Eastern Hellenic Arc (EHA - reference event 1303, Mw = 8.0) and the Cyprus Arc (CA - hypothetical scenario earthquake with Mw = 8.0), inferred from the tectonic setting and from historical tsunami catalogues. All numerical simulations are carried out by means of the code UBO-TSUFD, developed and maintained by the Tsunami Research Team of the University of Bologna. Relevant tsunami metrics are computed for each scenario and then used to build aggregated fields such as the maximum flood depth and the maximum inundation area. We find that the case that produces the most relevant flooding in Alexandria is the EHA scenario, with wave heights up to 4 m. The aggregate fields are used for a building vulnerability assessment according to a methodology developed in the frame of the EU-FP6 project SCHEMA and further refined in this study, based on the adoption of a suitable building damage matrix and on water inundation depth. It is found that in the districts of El Dekhila and Al Amriyah, to the south-west of the port of Dekhila over 12 000 buildings could be affected and hundreds of them could incur in consequences ranging from important damage to total collapse. It is also found that in the same districts tsunami inundation covers an area of about 15 km2 resulting in more than 150 000 residents being exposed.

  15. Histopathology of Incontinence-Associated Skin Lesions: Inner Tissue Damage Due to Invasion of Proteolytic Enzymes and Bacteria in Macerated Rat Skin

    PubMed Central

    Mugita, Yuko; Minematsu, Takeo; Huang, Lijuan; Nakagami, Gojiro; Kishi, Chihiro; Ichikawa, Yoshie; Nagase, Takashi; Oe, Makoto; Noguchi, Hiroshi; Mori, Taketoshi; Abe, Masatoshi; Sugama, Junko; Sanada, Hiromi

    2015-01-01

    A common complication in patients with incontinence is perineal skin lesions, which are recognized as a form of dermatitis. In these patients, perineal skin is exposed to digestive enzymes and intestinal bacterial flora, as well as excessive water. The relative contributions of digestive enzymes and intestinal bacterial flora to skin lesion formation have not been fully shown. This study was conducted to reveal the process of histopathological changes caused by proteases and bacterial inoculation in skin maceration. For skin maceration, agarose gel containing proteases was applied to the dorsal skin of male Sprague-Dawley rats for 4 h, followed by Pseudomonas aeruginosa inoculation for 30 min. Macroscopic changes, histological changes, bacterial distribution, inflammatory response, and keratinocyte proliferation and differentiation were examined. Proteases induced digestion in the prickle cell layer of the epidermis, and slight bleeding in the papillary dermis and around hair follicles in the macerated skin without macroscopic evidence of erosion. Bacterial inoculation of the skin macerated by proteolytic solution resulted in the formation of bacteria-rich clusters comprising numerous microorganisms and inflammatory cells within the papillary dermis, with remarkable tissue damage around the clusters. Tissue damage expanded by day 2. On day 3, the proliferative keratinocyte layer was elongated from the bulge region of the hair follicles. Application of proteases and P. aeruginosa induced skin lesion formation internally without macroscopic erosion of the overhydrated area, suggesting that the histopathology might be different from regular dermatitis. The healing process of this lesion is similar to transepidermal elimination. PMID:26407180

  16. Centerline Bed Elevation Profile of Sand Bed Channel due to Bar Formation

    NASA Astrophysics Data System (ADS)

    Tholibon, D. A.; Ariffin, J.; Abdullah, J.; Muhamad, N. S.

    2016-07-01

    Numerous data on bar formation have been accumulated yet the methods to predict bar geometry especially bar height are still insufficient. Objectives of this study to determine the trend in term of a significant difference of centreline bed elevation profile along the longitudinal distance. This can be investigate by carried out an experimental work in an erodible sand bed channel using a large-scale physical river model. The study included the various hydraulic characteristics with steady flow rates and sediment supply. An experimental work consists of four matrices of flow rate and channel width with other variables namely grains size and bed slope were kept constant. Analysis have included the discussion on a significant difference of centreline bed elevation profile along the longitudinal distance. As a conclusion the higher velocity in the smaller channel width have induced erosion of the banks that resulted in elevation increase while the larger flow rates have contributed to higher elevation.

  17. Formation of electric dipoles in pea stem tissue due to an electric field

    NASA Astrophysics Data System (ADS)

    Ahmadi, Fatemeh; Farahani, Elham

    2016-07-01

    For examining the effect of an electrical field (DC) on pea seed, we exposed the pea seeds to electric fields with intensities 1, 4 and 7 kV/cm for 30, 230, 430 and 630 seconds. The tests were repeated three times, and each iteration had 5 seeds. Then, the seeds were moved to packaged plates. Finally, microscopic observation of the pea stem tissue showed that the application of a DC electrical field caused a deformation in the pea stem tissue. The results led us to examine the deformation of the tissue theoretically and to address that deformation as an electrostatic problem. In this regard, we modeled the pea stem based on the formation of electric dipoles. Then, theoretically, we calculated the force acting on each xylem section by coding, and the results were consistent with the experimental data.

  18. Organogel Formation Due to the Self-Assembly of Dibenzylidene Sorbitol

    NASA Astrophysics Data System (ADS)

    Wilder, Elizabeth; Hall, Carol; Khan, Saad; Spontak, Richard

    2002-03-01

    Dibenzylidene sorbitol (DBS) is a small organic molecule that is capable of inducing gelation in a variety of organic solvents and polymers at low concentrations. In this study, a combination of rheological studies, electron microscopy, and computational methods were employed to probe the mechanisms involved in DBS-induced gelation. Rheological tests on DBS/poly(ethylene glycol) (PEG) gels reveal that as DBS concentration is increased, the gels exhibit greater elastic moduli, shorter gelation times, and maintain their connectivity at higher temperatures. Comparison of methoxy-capped PEG gels with hydroxy-capped PEG gels reveals that polar end groups interfere with network formation resulting in slower gelation times. Electron microscopy and tomography on DBS networks in poly(ethyl methacrylate) show that at low concentrations, DBS associates into small aggregates, while at higher concentrations fibrillar growth is evident. Molecular mechanical energy calculations suggest that DBS networks may form through a combination of intermolecular hydrogen bonding and pi-interactions.

  19. Formation of electron kappa distributions due to interactions with parallel propagating whistler waves

    SciTech Connect

    Tao, X. Lu, Q.

    2014-02-15

    In space plasmas, charged particles are frequently observed to possess a high-energy tail, which is often modeled by a kappa-type distribution function. In this work, the formation of the electron kappa distribution in generation of parallel propagating whistler waves is investigated using fully nonlinear particle-in-cell (PIC) simulations. A previous research concluded that the bi-Maxwellian character of electron distributions is preserved in PIC simulations. We now demonstrate that for interactions between electrons and parallel propagating whistler waves, a non-Maxwellian high-energy tail can be formed, and a kappa distribution can be used to fit the electron distribution in time-asymptotic limit. The κ-parameter is found to decrease with increasing initial temperature anisotropy or decreasing ratio of electron plasma frequency to cyclotron frequency. The results might be helpful to understanding the origin of electron kappa distributions observed in space plasmas.

  20. Simulation of surface profile formation in oxygen laser cutting of mild steel due to combustion cycles

    NASA Astrophysics Data System (ADS)

    Ermolaev, G. V.; Kovalev, O. B.

    2009-09-01

    A physicomathematical model of cyclic iron combustion in an oxygen flow during oxygen laser cutting of metal sheets is developed. The combustion front is set into motion by focused laser radiation and a heterogeneous oxidation reaction in oxygen. The burning rate is limited by oxygen supply from the gas phase towards the metal surface, and the interface motion depends on the local temperature. A 3D numerical simulation predicts wavy structures on the metal surface; their linear sizes depend on the scanning speed of the laser beam, the thickness of the produced liquid oxide film and the parameters of the oxygen jet flow. Simulation results help in understanding the mechanism of striation formation during oxygen gas-laser cutting of mild steel and are in qualitative agreement with experimental findings.

  1. Free radical formation in vivo and hepatotoxicity due to anesthesia with halothane

    SciTech Connect

    Plummer, J.L.; Beckwith, A.L.; Bastin, F.N.; Adams, J.F.; Cousins, M.J.; Hall, P.

    1982-09-01

    In vivo studies were undertaken to determine whether free radical formation in the liver during administration of various halogenated anesthetics is associated with hepatotoxicity of these agents in an animal model. In addition to the anesthetics halothane, enflurane, and isoflurane, carbon tetrachloride was studied as an example of a hepatotoxic halogenated compound acting by a free radical mechanism. Free radicals were trapped in vivo during anesthesia as stable adducts using the spin trap, alpha-phenyl-t-butyl nitrone. These adducts were extracted from the liver and studied by electron spin resonance spectrometry. Free radicals were detected after administration of halothane or carbon tetrachloride, compounds which were hepatotoxic under the conditions of the experiment, but were not found after anesthesia induced with enflurane or isoflurane, anesthetics which were not hepatotoxic under identical conditions. The free radical trapped after alpha-phenyl-t-butyl nitrone treatment of halothane-anesthetized rats appeared to be a metabolic intermediate of halothane.

  2. Arteriovenous fistula failure due to two straight shunts formation at draining vein.

    PubMed

    Tong, YanQing; Qi, WanLi; Sun, Min

    2013-01-01

    A 48-year-old asian man was admitted to hospital for the consideration of hemodialysis (HD). An adequate site was decided on for the AVF after Doppler ultrasonography examination of radial artery and cephalic vein. The AVF was formed under local anaesthetic at his right wrist. When seen at the clinic appointment one month later, the AVF was not working. The subsequent Doppler ultrasonography examination revealed two straight shunts at draining vein. The failure of AVF is due to impaired outflow following reduction of the resistance between draining vein and peripheral venous system.

  3. Reduction of Liquid Clad Formation Due to Solid State Diffusion in Clad Brazing Sheet

    NASA Astrophysics Data System (ADS)

    Benoit, Michael J.; Whitney, Mark A.; Wells, Mary A.; Winkler, Sooky

    2016-12-01

    Warm forming operations have shown promise in expanding automotive heat exchanger designs by increasing forming limits of clad brazing sheet. The impact of isothermal holds below the clad melting temperature on subsequent brazeability has not previously been studied in detail. The effect of these holds on brazeability, as measured by the clad thickness loss due to solid state diffusion of Si out of the clad layer prior to clad melting, was assessed through parallel DSC and optical microscopy measurements, as well as through the use of a previously developed model. EPMA measurements were also performed to support the other measures. Overall, the same trends were predicted by DSC, microscopy, and the theoretical model; however, the DSC predictions were unable to accurately predict remaining clad thickness prior to melting, even after correcting the data for clad-core interactions. Microscopy measurements showed very good agreement with the model predictions, although there were slight discrepancies at short hold times due to the inability of the model to account for clad loss during heating to the brazing temperature. Further microscopy measurements showed that when the heating rate is set below a critical value, there is a reduction in the clad thickness from the as-received condition.

  4. Amelioration of oxidative DNA damage in mouse peritoneal macrophages by Hippophae salicifolia due to its proton (H+) donation capability: Ex vivo and in vivo studies

    PubMed Central

    Chakraborty, Mainak; Karmakar, Indrajit; Haldar, Sagnik; Das, Avratanu; Bala, Asis; Haldar, Pallab Kanti

    2016-01-01

    Introduction: The present study evaluates the antioxidant effect of methanol extract of Hippophae salicifolia (MEHS) bark with special emphasis on its role on oxidative DNA damage in mouse peritoneal macrophages. Material and Methods: In vitro antioxidant activity was estimated by standard antioxidant assays whereas the antioxidant activity concluded the H+ donating capacity. Mouse erythrocytes’ hemolysis and peritoneal macrophages’ DNA damage were determined spectrophotometrically. In vivo antioxidant activity of MEHS was determined in carbon tetrachloride-induced mice by studying its effect on superoxide anion production in macrophages cells, superoxide dismutase in the cell lysate, DNA damage, lipid peroxidation, and reduces glutathione. Results: The extract showed good in vitro antioxidant activities whereas the inhibitory concentrations values ranged from 5.80 to 106.5 μg/ml. MEHS significantly (P < 0.05) attenuated the oxidative DNA damage. It also attenuated the oxidative conversion of hemoglobin to methemoglobin and elevation of enzymatic and nonenzymatic antioxidant in cells. Conclusion: The result indicates MEHS has good in vitro-in vivo antioxidant property as well as the protective effect on DNA and red blood cell may be due to its H+ donating property. PMID:27413349

  5. Agenesis of the Corpus Callosum Due to Defective Glial Wedge Formation in Lhx2 Mutant Mice.

    PubMed

    Chinn, Gregory A; Hirokawa, Karla E; Chuang, Tony M; Urbina, Cecilia; Patel, Fenil; Fong, Jeanette; Funatsu, Nobuo; Monuki, Edwin S

    2015-09-01

    Establishment of the corpus callosum involves coordination between callosal projection neurons and multiple midline structures, including the glial wedge (GW) rostrally and hippocampal commissure caudally. GW defects have been associated with agenesis of the corpus callosum (ACC). Here we show that conditional Lhx2 inactivation in cortical radial glia using Emx1-Cre or Nestin-Cre drivers results in ACC. The ACC phenotype was characterized by aberrant ventrally projecting callosal axons rather than Probst bundles, and was 100% penetrant on 2 different mouse strain backgrounds. Lhx2 inactivation in postmitotic cortical neurons using Nex-Cre mice did not result in ACC, suggesting that the mutant phenotype was not autonomous to the callosal projection neurons. Instead, ACC was associated with an absent hippocampal commissure and a markedly reduced to absent GW. Expression studies demonstrated strong Lhx2 expression in the normal GW and in its radial glial progenitors, with absence of Lhx2 resulting in normal Emx1 and Sox2 expression, but premature exit from the cell cycle based on EdU-Ki67 double labeling. These studies define essential roles for Lhx2 in GW, hippocampal commissure, and corpus callosum formation, and suggest that defects in radial GW progenitors can give rise to ACC.

  6. Modelling of cloud formation due to air-sea interactions in an energy-active zone

    NASA Astrophysics Data System (ADS)

    Kondratyev, K. Ya.; Khvorostyanov, V. I.

    1989-02-01

    A mesoscale 3D numerical model is described, with which detailed calculations have been made of turbulence and wind characteristics in the atmospheric boundary layer (ABL), as well as cloud particle size distribution, longwave and solar radiation fluxes and flux divergences, and atmosphere-ocean heat exchange. Based on numerical experiments simulating winter conditions of the Newfoundland energy-active zone of the ocean (EAZO), atmosphere-ocean energy exchange is investigated. It is shown that the basic mechanisms for the EAZO formation involve the following processes: (i) at the hydrological front between cold and warm ocean currents, the fluxes of sensible and latent heat grow significantly; (ii) at this front, in a particular synoptic situation, overcast low-level cloudiness forms, screening solar radiation so that in winter, the radiation budget at the front is reduced, and the radiative flux into the ocean is less than the energy release to the atmosphere; (iii) frequent occurrence of such synoptic situations with cloudiness decreases the oceanic enthalpy and creates negative SST anomalies. The transport of these anomalies by currents to the western coasts of the continents causes anomalies of weather and climate.

  7. Subsurface deuterium bubble formation in W due to low-energy high flux deuterium plasma exposure

    NASA Astrophysics Data System (ADS)

    Jia, Y. Z.; Liu, W.; Xu, B.; Qu, S. L.; Shi, L. Q.; Morgan, T. W.

    2017-03-01

    The deuterium (D) bubbles formed in W exposed to high flux D plasma were researched by scanning electron microscopy and transmission electron microscopy. After D plasma exposure at 500 K and 1000 K, a layer of nano-sized bubbles were homogenously distributed in W subsurface region. The D bubbles were homogenously nucleated due to the high D concentration, and the nucleation process is not related to the vacancy defects. At low temperature (500 K), D bubbles can grow by surface blistering, which caused different nano scale morphologies on different surfaces. At high temperature (1000 K), D bubbles mainly grow by vacancy clustering, which caused pinholes on the surface.

  8. Formation of a chronic pain syndrome due to mesh shrinkage after laparoscopic intraperitoneal onlay mesh (IPOM).

    PubMed

    Klein, Fritz; Ospina, Carlos; Rudolph, Birgit; Wüstefeld, Joost; Denecke, Timm; Neuhaus, Peter; Schmidt, Sven-Christian

    2012-10-01

    The case of a 58-year-old male patient who developed a chronic pain syndrome after laparoscopic intraperitoneal onlay mesh for treatment of a large symptomatic umbilical hernia combined with rectus diastasis is reported. Twelve months after an uncomplicated initial surgery, the patient presented with progressive signs of a foreign body sensation and pain in the anterior abdominal wall. Computed tomography examination revealed no pathologic findings but a marked shrinkage of the mesh implant. Because of further progressive symptoms, explorative laparotomy was performed. Mesh shrinkage and adhesions with a surrounding chronic tissue reaction were found as the cause of the pain syndrome. This case demonstrates a case of a chronic pain syndrome due to mesh shrinkage 12 months after initial ventral hernia repair. Mesh shrinkage should therefore be taken into consideration in patients with progressive pain chronic syndromes after laparoscopic ventral hernia repair.

  9. Decrease in Corneal Damage due to Benzalkonium Chloride by the Addition of Mannitol into Timolol Maleate Eye Drops.

    PubMed

    Nagai, Noriaki; Yoshioka, Chiaki; Tanino, Tadatoshi; Ito, Yoshimasa; Okamoto, Norio; Shimomura, Yoshikazu

    2015-01-01

    We investigated the protective effects of mannitol on corneal damage caused by benzalkonium chloride (BAC), which is used as a preservative in commercially available timolol maleate eye drops, using rat debrided corneal epithelium and a human cornea epithelial cell line (HCE-T). Corneal wounds were monitored using a fundus camera TRC-50X equipped with a digital camera; eye drops were instilled into rat eyes five times a day after corneal epithelial abrasion. The viability of HCE-T cells was calculated by TetraColor One; and Escherichia coli (ATCC 8739) were used to measure antimicrobial activity. The reducing effects on transcorneal penetration and intraocular pressure (IOP) of the eye drops were determined using rabbits. The corneal wound healing rate and rate constant (kH), as well as cell viability, were higher following treatment with 0.005% BAC solution containing 0.5% mannitol than in the case BAC solution alone; the antimicrobial activity was approximately the same for BAC solutions with and without mannitol. In addition, the kH for rat eyes instilled with commercially available timolol maleate eye drops containing 0.5% mannitol was significantly higher than that for eyes instilled with timolol maleate eye drops without mannitol, and the addition of mannitol did not affect the corneal penetration or IOP reducing effect of the timolol maleate eye drops. A preservative system comprising BAC and mannitol may provide effective therapy for glaucoma patients requiring long-term treatment with anti-glaucoma agents.

  10. Effects on detection of radical formation in skin due to solar irradiation measured by EPR spectroscopy.

    PubMed

    Albrecht, Stephanie; Ahlberg, Sebastian; Beckers, Ingeborg; Kockott, Dieter; Lademann, Jürgen; Paul, Victoria; Zastrow, Leonhard; Meinke, Martina C

    2016-10-15

    In various research projects, oxidative stress in irradiated skin was investigated by measuring the production of free radical using EPR spectroscopy. However, comparison of the obtained measuring results proved to be difficult as different preparation parameters were used for those measurements. In the present study the influence of the preparation parameters on the detected radical production was methodically investigated. For this purpose, porcine skin was exposed in situ to UV and VIS-NIR radiation, respectively, while being measured in an X band EPR spectrometer. Prior to the measurements, the skin had been treated with the spin trap N-tert-Butyl-α-phenylnitrone (PBN) and the spin marker 3-(Carboxyl)-2,2,5,5-tetramethyl-1-pyrrolidinyloxy (PCA). The two methods were investigated for quantitative comparability, for advantages and disadvantages and for errors potentially affecting the evaluation of the results. A significant influence of the preparation parameters (concentration and amount of substance) on the detected radical formations could be found. This influence had a nonlinear effect on the detected radical production. 120μl of incubated amount for 1M PBN and for PCA at a concentration of 0.6 and 1.5mM were determined to be the optimum parameters. The incubated skin samples were 1cm in diameter and 300μm thick. Between 22 and 37°C the incubation temperature showed no significant influence on the detected radical production. For the first time it could be demonstrated for PCA-incubated skin that the radiation-induced radical production depends exclusively on the irradiation dose, provided the preparation parameters and the spectral region are kept constant. In addition, the radical production in the UVB-UVA and VIS-NIR spectral regions was measured in PCA- and PBN-treated excised porcine skin. It was found that PBN and PCA provide comparable results for the relative quantity and kinetics of radical production.

  11. Solar Wind Strahl Observations and Their Implication to the Core-Halo Formation due to Scattering

    NASA Technical Reports Server (NTRS)

    Vinas, Adolfo F.

    2011-01-01

    A study of the kinetic properties of the strahl electron velocity distribution functions (VDF?s) in the solar wind is presented. This study focuses on the mechanisms that control and regulate the electron VDF?s and the stability of the strahl electrons in the solar wind; mechanisms that are not yet well understood. Various parameters are investigated such as the strahl-electron density, temperature anisotropy, and electron heat-flux. These parameters are used to investigate the stability of the strahl population. The analysis check for whether the strahl electrons are constrained by some instability (e.g., the whistler or KAW instabilities), or are maintained by other types of processes. The electron heat-flux and temperature anisotropy are determined by modeling of the 3D-VDF?s from which the moments properties of the various populations are obtained. The results of this study have profound implication on the current hypothesis about the probable formation of the solar wind halo electrons produced from the scattering of the strahl population. This hypothesis is strengthened by direct observations of the strahl electrons being scattered into the core-halo in an isolated event. The observation implies that the scattering of the strahl is not a continuous process but occurs in bursts in regions where conditions for wave growth providing the scattering are optimum. Sometimes, observations indicate that the strahl component is anisotropic (Tper/Tpal approx. 2). This provides a possible free energy source for the excitation of whistler waves as a possible scattering mechanism, however this condition is not always observed. The study is based on high time resolution data from the Cluster/PEACE electron spectrometer.

  12. Permeability evolution of fractured limestone due to reactive flow: Observation and prediction of wormhole formation

    NASA Astrophysics Data System (ADS)

    Deng, H.; Fitts, J. P.; Crandall, D.; McIntyre, D.; Peters, C. A.

    2014-12-01

    Fractures in porous media provide preferential pathways for flow and solute transport. Their hydraulic properties are critical parameters for determining fluid migration and leakage, and are subject to alterations when exposed to reactive flow, e.g. CO2-acidfied brine in the case of carbon storage. Our previous studies have shown how mineral heterogeneity could lead to increased roughness that mitigates the increase in fracture permeability. This study shows that, even in rocks with mineral homogeneity, fracture geometry is subject to complex alterations. In this presentation, we report an experimental study of CO2-acidified brine in fractured Indiana Limestone, with comprehensive characterization of effluent chemistry analyzed by ICP-OES, and 3D geometry evolution using micro-computed topography (xCT). Significant carbonate dissolution was observed but the reaction extent revealed by the effluent chemistry was less than what was predicted by simple reaction transport models. xCT imaging revealed the formation of wormhole channels in the fracture, and the channels grew larger downstream and more prominent over time. Using the fracture geometries derived from the xCT images, we simulated the flow field and inferred the evolution of fracture hydraulic properties. To interpret the process of wormholing and its impacts on fracture hydraulic properties, we used reactive transport modeling to simulate the interplay between fracture geometry, fluid flow and geochemical reactions. Our simulations predicted that wormholes were formed in fractures with initial roughness representative of natural subsurface systems. The presence of wormholes caused a disproportionately larger permeability increase than would be expected given the extent of volume change.

  13. Parametric studies on confinement of radionuclides in the excavated damaged zone due to bentonite type and temperature change

    NASA Astrophysics Data System (ADS)

    Borrelli, R. A.; Thivent, Olivier; Ahn, Joonhong

    A parametric study is presented in this paper in order to examine the potential of the extruding bentonite into a fracture in the EDZ to confine radionuclides. Radionuclide migration of cesium and neptunium were studied at elevated temperatures and for a sodium- and calcium-type bentonite. Parameter values were obtained based on empirical studies for hydraulic conductivity, molecular diffusion, and sorption. Results indicate extrusion speed is affected by temperature changes. Elevated temperatures also affect radionuclide migration. For Cs, migration is enhanced due to decreasing sorption, while Np migration is inhibited due to increasing sorption. The potential to confine radionuclides is favorable, and the choice of bentonite does not seem to affect radionuclide confinement in the extruding region.

  14. Influence of age on brain edema formation, secondary brain damage and inflammatory response after brain trauma in mice.

    PubMed

    Timaru-Kast, Ralph; Luh, Clara; Gotthardt, Philipp; Huang, Changsheng; Schäfer, Michael K; Engelhard, Kristin; Thal, Serge C

    2012-01-01

    After traumatic brain injury (TBI) elderly patients suffer from higher mortality rate and worse functional outcome compared to young patients. However, experimental TBI research is primarily performed in young animals. Aim of the present study was to clarify whether age affects functional outcome, neuroinflammation and secondary brain damage after brain trauma in mice. Young (2 months) and old (21 months) male C57Bl6N mice were anesthetized and subjected to a controlled cortical impact injury (CCI) on the right parietal cortex. Animals of both ages were randomly assigned to 15 min, 24 h, and 72 h survival. At the end of the observation periods, contusion volume, brain water content, neurologic function, cerebral and systemic inflammation (CD3+ T cell migration, inflammatory cytokine expression in brain and lung, blood differential cell count) were determined. Old animals showed worse neurological function 72 h after CCI and a high mortality rate (19.2%) compared to young (0%). This did not correlate with histopathological damage, as contusion volumes were equal in both age groups. Although a more pronounced brain edema formation was detected in old mice 24 hours after TBI, lack of correlation between brain water content and neurological deficit indicated that brain edema formation is not solely responsible for age-dependent differences in neurological outcome. Brains of old naïve mice were about 8% smaller compared to young naïve brains, suggesting age-related brain atrophy with possible decline in plasticity. Onset of cerebral inflammation started earlier and primarily ipsilateral to damage in old mice, whereas in young mice inflammation was delayed and present in both hemispheres with a characteristic T cell migration pattern. Pulmonary interleukin 1β expression was up-regulated after cerebral injury only in young, not aged mice. The results therefore indicate that old animals are prone to functional deficits and strong ipsilateral cerebral inflammation

  15. Influence of Age on Brain Edema Formation, Secondary Brain Damage and Inflammatory Response after Brain Trauma in Mice

    PubMed Central

    Timaru-Kast, Ralph; Luh, Clara; Gotthardt, Philipp; Huang, Changsheng; Schäfer, Michael K.; Engelhard, Kristin; Thal, Serge C.

    2012-01-01

    After traumatic brain injury (TBI) elderly patients suffer from higher mortality rate and worse functional outcome compared to young patients. However, experimental TBI research is primarily performed in young animals. Aim of the present study was to clarify whether age affects functional outcome, neuroinflammation and secondary brain damage after brain trauma in mice. Young (2 months) and old (21 months) male C57Bl6N mice were anesthetized and subjected to a controlled cortical impact injury (CCI) on the right parietal cortex. Animals of both ages were randomly assigned to 15 min, 24 h, and 72 h survival. At the end of the observation periods, contusion volume, brain water content, neurologic function, cerebral and systemic inflammation (CD3+ T cell migration, inflammatory cytokine expression in brain and lung, blood differential cell count) were determined. Old animals showed worse neurological function 72 h after CCI and a high mortality rate (19.2%) compared to young (0%). This did not correlate with histopathological damage, as contusion volumes were equal in both age groups. Although a more pronounced brain edema formation was detected in old mice 24 hours after TBI, lack of correlation between brain water content and neurological deficit indicated that brain edema formation is not solely responsible for age-dependent differences in neurological outcome. Brains of old naïve mice were about 8% smaller compared to young naïve brains, suggesting age-related brain atrophy with possible decline in plasticity. Onset of cerebral inflammation started earlier and primarily ipsilateral to damage in old mice, whereas in young mice inflammation was delayed and present in both hemispheres with a characteristic T cell migration pattern. Pulmonary interleukin 1β expression was up-regulated after cerebral injury only in young, not aged mice. The results therefore indicate that old animals are prone to functional deficits and strong ipsilateral cerebral inflammation

  16. White Layer Formation Due to Phase Transformation to Orthogonal machine of AISI 1045 Annealed Steel

    SciTech Connect

    Han, Sangil; Melkote, Shreyes N; Haluska, Dr. Michael S; Watkins, Thomas R

    2008-01-01

    It is commonly believed that the white layer formed during machining of steels is caused primarily by a thermally induced phase transformation resulting from rapid heating and quenching. As a result, it is often assumed that if the temperature at the tool flank-workpiece interface exceeds the nominal phase transformation temperature for the steel, a white layer forms. However, no attempt has been made to actually measure the temperatures produced at the tool flank-workpiece interface and correlate it with microstructural evidence of phase transformation. This paper aims to address these limitations through suitably designed experiments and analysis. Orthogonal machining tests were performed on AISI 1045 annealed steel at different cutting speeds and tool flank wear. During machining, temperature measurements at the tool flank-workpiece interface were made using an exposed thermocouple technique. Metallographic studies of the machined sub-surface and X-ray diffraction (XRD) measurements were performed to determine the presence and depth of white layer, and the presence of the retained austenite phase in the machined surface layer, respectively. Analysis of the data shows that the white layer can form due to phase transformation at temperatures below the nominal austenitization temperature of the steel. Possible causes of this result are presented.

  17. [Fungal infectivities of implanted catheters due to Candida sp. Biofilms formation and resistance].

    PubMed

    Seddiki, S M L; Boucherit-Otmani, Z; Boucherit, K; Kunkel, D

    2015-06-01

    Candidemia are the most common fungal infections in hospitals. However, the catheters are subject to be altered by Candida biofilms which increase the risk of invasive nosocomial infections due to the high resistance to antifungal agents. Therefore, the minimum inhibitory concentrations of planktonic (MIC) and sessile cells (CIMS) were evaluated. To review the in vivo biofilms structures of Candida sp. formed on the inner and/or external surfaces of collected catheters, we used scanning electron microscopy (SEM). The level of biofilm resistance was assessed against two conventional antifungal agents: amphotericin B (AmB), which belongs to the class of polyenes, and fluconazole (FLZ) which is an azole. The SEM observation of biofilms of Candida sp. reveals complex structures. Compared to MICs, the calculation of CIMS showed an increase of 32 times with AmB and of 128 times with FLZ. Catheters offer an ideal surface to Candida sp. to form biofilms. This complex structure induces the increase of the resistance of sessile cells against two antifungal agents, AmB and FLZ. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  18. Bottomwater formation due to hydrothermal activity in Frolikha Bay, Lake Baikal, eastern Siberia

    SciTech Connect

    Kipfer, R.; Aeschbach-Hertig, W.; Hofer, M.; Hohmann, R.; Imboden, D.M.

    1996-03-01

    Hydrothermal water enters Frolikha Bay, a well-known site of high geothermal heat flux in the northern part of Lake Baikal, at 400 m depth. On the basis of CTD profiles, the hydrothermal water is identified as forming an anomalous bottom layer with a higher temperature (>0.15{degrees}C) and salinity (>2.5 mg{center_dot}kg{sup {minus}1}) than the overlying water. Due to the entrainment of lake water, a distinct dense water layer up to 40 m thick, stabilised by its slightly higher salinity, becomes established close to the bottom of the bay. The density current thus generated flows out of the bay towards the deeper parts of the basin. Since helium isotope analysis shows that the geochemical characteristics of the hydrothermal water are similar to those of water from nearby hot springs on land, the bottomwater of Frolikha Bay is easily interpreted in terms of the mixing of ordinary fresh water from the lake and hydrothermal water carrying isotopically heavy He from the continental crust. Because of its high crustal He content, a similar hydrothermal component may even be identified in the open water of the northern basin. 39 refs., 6 figs., 3 tabs.

  19. Output switching in a semiconductor circular ring resonator due to solitons wave formation

    NASA Astrophysics Data System (ADS)

    Shih, Ming Chang; Yen, Chun Liang

    2014-01-01

    Here we demonstrated the phenomena of switching of the coupling in an InGaAlP multiple-quantum-well semiconductor circular ring resonator due to the generation of solitons wave guiding. The fabricated device is consisted of a circular ridge waveguide ring resonator with diameter range from 150 to 250 µm with two Y-junction directional couplers for output coupling of clockwise/counter clockwise (CW/CCW) modes. Ridge waveguide of 1.1 and 0.8 µm depth were fabricated to study the effect in solitons generation. It showed that for the 1.1 µm etched depth waveguide, CW and CCW modes in the ring resonator were coupled out through each Y-junction couplers respectively. However, for the 0.8 µm depth waveguide when spatial solitons was formed, coupling of the CCW modes in the circular ring resonator was switched from Y-junction coupler to the spatial solitons guiding terminal. Measurements of light-current (L-I) and spectral characteristics were studied to enunciate the mechanism of output modes switching in circular ring resonator.

  20. Measurement of changes in impedance of DNA nanowires due to radiation induced structural damage. A novel approach for a DNA-based radiosensitive device

    NASA Astrophysics Data System (ADS)

    Heimbach, Florian; Arndt, Alexander; Nettelbeck, Heidi; Langner, Frank; Giesen, Ulrich; Rabus, Hans; Sellner, Stefan; Toppari, Jussi; Shen, Boxuan; Baek, Woon Yong

    2017-08-01

    The ability of DNA to conduct electric current has been the topic of numerous investigations over the past few decades. Those investigations indicate that this ability is dependent on the molecular structure of the DNA. Radiation-induced damages, which lead to an alteration of the molecular structure, should therefore change the electrical impedance of a DNA molecule. In this paper, the damage due to ionising radiation is shown to have a direct effect on the electrical transport properties of DNA. Impedance measurements of DNA samples were carried out by an AC impedance spectrometer before, during and after irradiation. The samples comprised of DNA segments, which were immobilized between gold electrodes with a gap of 12 μm. The impedance of all DNA samples exhibited rising capacitive behaviour with increasing absorbed dose.

  1. Spatial Distribution of Adult Anthonomus grandis Boheman (Coleoptera: Curculionidae) and Damage to Cotton Flower Buds Due to Feeding and Oviposition.

    PubMed

    Grigolli, J F J; Souza, L A; Fernandes, M G; Busoli, A C

    2016-12-12

    The cotton boll weevil Anthonomus grandis Boheman (Coleoptera: Curculionidae) is the main pest in cotton crop around the world, directly affecting cotton production. In order to establish a sequential sampling plan, it is crucial to understand the spatial distribution of the pest population and the damage it causes to the crop through the different developmental stages of cotton plants. Therefore, this study aimed to investigate the spatial distribution of adults in the cultivation area and their oviposition and feeding behavior throughout the development of the cotton plants. The experiment was conducted in Maracaju, Mato Grosso do Sul, Brazil, in the 2012/2013 and 2013/2014 growing seasons, in an area of 10,000 m(2), planted with the cotton cultivar FM 993. The experimental area was divided into 100 plots of 100 m(2) (10 × 10 m) each, and five plants per plot were sampled weekly throughout the crop cycle. The number of flower buds with feeding and oviposition punctures and of adult A. grandis was recorded throughout the crop cycle in five plants per plot. After determining the aggregation indices (variance/mean ratio, Morisita's index, exponent k of the negative binomial distribution, and Green's coefficient) and adjusting the frequencies observed in the field to the distribution of frequencies (Poisson, negative binomial, and positive binomial) using the chi-squared test, it was observed that flower buds with punctures derived from feeding, oviposition, and feeding + oviposition showed an aggregated distribution in the cultivation area until 85 days after emergence and a random distribution after this stage. The adults of A. grandis presented a random distribution in the cultivation area.

  2. Hypochlorite-induced damage to DNA, RNA, and polynucleotides: formation of chloramines and nitrogen-centered radicals.

    PubMed

    Hawkins, Clare L; Davies, Michael J

    2002-01-01

    Stimulated monocytes and neutrophils generate hypochlorite (HOCl) via the release of the enzyme myeloperoxidase and hydrogen peroxide. HOCl is a key bactericidal agent, but can also damage host tissue. As there is a strong link between chronic inflammation and some cancers, we have investigated HOCl damage to DNA, RNA, and polynucleotides. Reaction of HOCl with these materials is shown to yield multiple semistable chloramines (RNHCl/RR'NCl), which are the major initial products, and account for 50-95% of the added HOCl. These chloramines decay by thermal and metal-ion catalyzed processes, to give nucleoside-derived, nitrogen-centered, radicals. The latter have been characterized by EPR spin trapping. The propensity for radical formation with polynucleotides is cytidine > adenosine = guanosine > uridine = thymidine. The rates of decay, and yield of radicals formed, are dependent on the nature of the nucleobase on which they are formed, with chloramines formed from ring heterocyclic amine groups being less stable than those formed on exocyclic amines (RNH2 groups). Evidence is presented for chlorine transfer from the former, kinetically favored, sites to the more thermodynamically favored exocyclic amines. EPR experiments have also provided evidence for the rapid addition of pyrimidine-derived nitrogen-centered radicals to other nucleobases to give dimers and the oxidation of DNA by radicals derived from preformed nucleoside chloramines. Direct reaction of HOCl with plasmid DNA gives rise to single- and double-strand breaks via chloramine-mediated reactions. Preformed nucleoside chloramines also induce plasmid cleavage, though this only occurs to a significant extent with unstable thymidine- and uridine-derived chloramines, where radical formation is rapid. Overall the data rationalize the preferential formation of chlorinated 2'-deoxycytidine and 2'-deoxyadenosine in DNA and suggest that DNA damage induced by HOCl, and preformed chloramines, occurs at sequence

  3. Novel mechanism of premature battery failure due to lithium cluster formation in implantable cardioverter-defibrillators.

    PubMed

    Pokorney, Sean D; Greenfield, Ruth Ann; Atwater, Brett D; Daubert, James P; Piccini, Jonathan P

    2014-12-01

    Battery failure is an uncommon complication of implantable cardioverter-defibrillators (ICDs), but unanticipated battery depletion can have life-threatening consequences. The purpose of this study was to describe the prevalence of a novel mechanism of battery failure in St. Jude Medical Fortify and Unify ICDs. Cases of premature Fortify battery failure from a single center are reported. A search (January 1, 2010 through November 30, 2013) for Fortify and Unify premature batter failure was conducted of the Food and Drug Administration's Manufacturer and User Facility Device Experience Database (MAUDE). These findings were supplemented with information provided by St. Jude Medical. Premature battery failure for 2 Fortify ICDs in our practice were attributed to the presence of lithium clusters near the cathode, causing a short circuit and high current drain. The prevalence of this mechanism of premature battery failure was 0.6% in our practice. A MAUDE search identified 39 cases of Fortify (30) and Unify (9) premature battery depletion confirmed by the manufacturer, representing a 0.03% prevalence. Four additional Fortify and 2 Unify cases were identified in MAUDE as suspected premature battery depletion, but in these cases the pulse generator was not returned to the manufacturer for evaluation. St. Jude Medical identified 10 cases of premature battery failure due to lithium clusters in Fortify devices (9) and Unify devices (1), representing a 0.004% prevalence. The deposition of lithium clusters near the cathode is a novel mechanism of premature battery failure. The prevalence of this problem is unknown. Providers should be aware of this mechanism for patient management. Copyright © 2014 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  4. Fibrinogen triggers astrocyte scar formation by promoting the availability of active TGF-β after vascular damage

    PubMed Central

    Schachtrup, Christian; Ryu, Jae K.; Helmrick, Matthew; Vagena, Eirini; Galanakis, Dennis K.; Degen, Jay L.; Margolis, Richard U.; Akassoglou, Katerina

    2010-01-01

    Scar formation in the nervous system begins within hours after traumatic injury and is characterized primarily by reactive astrocytes depositing proteoglycans that inhibit regeneration. A fundamental question in CNS repair has been the identity of the initial molecular mediator that triggers glial scar formation. Here we show that the blood protein fibrinogen, which leaks into the CNS immediately after blood-brain barrier (BBB) disruption or vascular damage, serves as an early signal for the induction of glial scar formation via the TGF-β/Smad signaling pathway. Our studies revealed that fibrinogen is a carrier of latent TGF-β and induces phosphorylation of Smad2 in astrocytes that leads to inhibition of neurite outgrowth. Consistent with these findings, genetic or pharmacologic depletion of fibrinogen in mice reduces active TGF-β, Smad2 phosphorylation, glial cell activation and neurocan deposition following cortical injury. Furthermore, stereotactic injection of fibrinogen into the mouse cortex is sufficient to induce astrogliosis. Inhibition of the TGF-β receptor pathway abolishes the fibrinogen-induced effects on glial scar formation in vivo and in vitro. These results identify fibrinogen as a primary astrocyte activation signal, provide evidence that deposition of inhibitory proteoglycans is induced by a blood protein that leaks in the CNS after vasculature rupture, and point to TGF-β as a molecular link between vascular permeability and scar formation. PMID:20427645

  5. HDAC inhibitor sodium butyrate sensitizes E1A+Ras-transformed cells to DNA damaging agents by facilitating formation and persistence of γH2AX foci.

    PubMed

    Abramova, Maria V; Svetlikova, Svetlana B; Kukushkin, Alexander N; Aksenov, Nikolai D; Pospelova, Tatiana V; Pospelov, Valery A

    2011-12-15

    HDAC inhibitors (HDACi) suppress the growth of tumor cells due to induction of cell cycle arrest, senescence or apoptosis. Recent data demonstrate that HDACi can interfere with DNA Damage Response (DDR) thereby sensitizing the cells to DNA damaging agents. Here, we show that HDACi sodium butyrate (NaBut) potentiates the formation of γH2AX foci predominantly in S-phase E1A+Ras cells. Accumulation of γH2AX foci sensitizes the cells toward such DNA damaging agents as irradiation (IR) and adriamycin. In fact, NaBut potentiates the persistence of γH2AX foci induced by genotoxic agents. The synergizing effects depend on DNA damaging factors and on the order of NaBut treatment. Indeed, NaBut treatment for 24 h leads to an accumulation of G 1-phase cells and a lack of S-phase cells, therefore, adriamycin, a powerful S-phase-specific inhibitor, when added to NaBut-treated cells, is unable to substantially add γH2AX foci. In contrast, IR produces both single- and double-strand DNA breaks at any stage of the cell cycle and was shown to increase γH2AX foci in NaBut-treated cells. Further, a lifetime of IR-induced γH2AX foci depends on the subsequent presence of HDACi. Correspondingly, NaBut withdrawal leads to the extinction of IR-induced γH2AX foci. This necessitates HDACi to hold the IR-induced γH2AX foci unrepaired. However, the IR-induced γH2AX foci persist after long-term NaBut treatment (72 h) even after washing the drug. Thus, although signaling pathways regulating H2AX phosphorylation in NaBut-treated cells remain to be investigated, the obtained results show that NaBut potentiates effects of DNA damaging agents by facilitating formation and persistence of γH2AX foci.

  6. Formation of singlet oxygen and protection against its oxidative damage in Photosystem II under abiotic stress.

    PubMed

    Pospíšil, Pavel; Prasad, Ankush

    2014-08-01

    Photosystem II (PSII) is exposed to various abiotic stresses associated with adverse environmental conditions such as high light, heat, heavy metals or mechanical injury. Distinctive functional response to adverse environmental conditions is formation of singlet oxygen ((1)O2). In this review, recent progress on mechanistic principles on (1)O2 formation under abiotic stresses is summarized. Under high light, (1)O2 is formed by excitation energy transfer from triplet chlorophylls to molecular oxygen formed by the spin conversion via photosensitization Type II reaction in the PSII antenna complex or by the recombination of (1)[P680(+)Pheo(-)] radical pair in the PSII reaction center. Apart from well-described (1)O2 formation by excitation energy transfer, (1)O2 formation by decomposition of dioxetane and tetroxide is summarized as a potential source of (1)O2 in PSII under heat, heavy metals and mechanical stress. The description of mechanistic principles on (1)O2 formation under abiotic stress allows us to understand how plants respond to adverse environmental conditions in vivo.

  7. Impacts of plasma-induced damage due to UV light irradiation during etching on Ge fin fabrication and device performance of Ge fin field-effect transistors

    NASA Astrophysics Data System (ADS)

    Mizubayashi, Wataru; Noda, Shuichi; Ishikawa, Yuki; Nishi, Takashi; Kikuchi, Akio; Ota, Hiroyuki; Su, Ping-Hsun; Li, Yiming; Samukawa, Seiji; Endo, Kazuhiko

    2017-02-01

    We investigated the impacts of plasma-induced damage due to UV light irradiation during etching on Ge fin fabrication and the device performance of Ge fin field-effect transistors (Ge FinFETs). UV light irradiation during etching affected the shape of the Ge fin and the surface roughness of the Ge fin sidewall. A vertical and smooth Ge fin could be fabricated by neutral beam etching without UV light irradiation. The performances of Ge FinFETs fabricated by neutral beam etching were markedly improved as compared to those of Ge FinFETs fabricated by inductively coupled plasma etching, in which the UV light has an impact.

  8. Impairment of vitamin D metabolism due to environmental cadmium exposure, and possible relevance to sex-related differences in vulnerability to the bone damage

    SciTech Connect

    Tsuritani, Ikiko; Honda, Ryumon; Ishizaki, Masao; Yamada, Yuichi ); Kido, Teruhiko; Nogawa, Koji )

    1992-12-01

    To determine whether depleted serum 1[alpha],25-dihydroxyvitamin D (VD) concentrations are associated with cadmium (Cd)-induced renal damage, the relationships between four indices of renal function and two indicators of bone metabolism, that is, serum VD and parathyroid hormone (PTH) concentrations, were analyzed in 30 male and 44 female subjects exposed to environmental Cd. Also, these associations were compared in male and female subjects to evaluate sex-related differences in vulnerability to the bone damage observed in Cd-exposed persons. Serum VD decreased significantly with declines in creatinine clearance and percentage tubular reabsorption of phosphate, and with increases in serum creatinine and serum [beta][sub 2]-microglobulin ([beta][sub 2]m) concentrations in the female subjects exposed to Cd, but not in the male subjects. The correlation between serum VD and PTH levels was also significant only in the females. Correlation coefficients between serum [beta][sub 2]m and VD and those between serum PTH and VD in both sexes were significantly different. These results suggest that renal damage due to Cd exposure leads to the decreases in the serum VD level and increases in serum PTH level, and that the more marked changes in serum VD and PTH in the women may play a role in the development of sex-related differences in Cd-induced bone injury.

  9. Reduced-Order Modeling and Wavelet Analysis of Turbofan Engine Structural Response Due to Foreign Object Damage "FOD" Events

    NASA Technical Reports Server (NTRS)

    Turso, James A.; Lawrence, Charles; Litt, Jonathan S.

    2007-01-01

    The development of a wavelet-based feature extraction technique specifically targeting FOD-event induced vibration signal changes in gas turbine engines is described. The technique performs wavelet analysis of accelerometer signals from specified locations on the engine and is shown to be robust in the presence of significant process and sensor noise. It is envisioned that the technique will be combined with Kalman filter thermal/ health parameter estimation for FOD-event detection via information fusion from these (and perhaps other) sources. Due to the lack of high-frequency FOD-event test data in the open literature, a reduced-order turbofan structural model (ROM) was synthesized from a finite-element model modal analysis to support the investigation. In addition to providing test data for algorithm development, the ROM is used to determine the optimal sensor location for FOD-event detection. In the presence of significant noise, precise location of the FOD event in time was obtained using the developed wavelet-based feature.

  10. Reduced-Order Modeling and Wavelet Analysis of Turbofan Engine Structural Response Due to Foreign Object Damage "FOD" Events

    NASA Technical Reports Server (NTRS)

    Turso, James A.; Lawrence, Charles; Litt, Jonathan S.

    2007-01-01

    The development of a wavelet-based feature extraction technique specifically targeting FOD-event induced vibration signal changes in gas turbine engines is described. The technique performs wavelet analysis of accelerometer signals from specified locations on the engine and is shown to be robust in the presence of significant process and sensor noise. It is envisioned that the technique will be combined with Kalman filter thermal/ health parameter estimation for FOD-event detection via information fusion from these (and perhaps other) sources. Due to the lack of high-frequency FOD-event test data in the open literature, a reduced-order turbofan structural model (ROM) was synthesized from a finite-element model modal analysis to support the investigation. In addition to providing test data for algorithm development, the ROM is used to determine the optimal sensor location for FOD-event detection. In the presence of significant noise, precise location of the FOD event in time was obtained using the developed wavelet-based feature.

  11. Reduced-Order Modeling and Wavelet Analysis of Turbofan Engine Structural Response Due to Foreign Object Damage (FOD) Events

    NASA Technical Reports Server (NTRS)

    Turso, James; Lawrence, Charles; Litt, Jonathan

    2004-01-01

    The development of a wavelet-based feature extraction technique specifically targeting FOD-event induced vibration signal changes in gas turbine engines is described. The technique performs wavelet analysis of accelerometer signals from specified locations on the engine and is shown to be robust in the presence of significant process and sensor noise. It is envisioned that the technique will be combined with Kalman filter thermal/health parameter estimation for FOD-event detection via information fusion from these (and perhaps other) sources. Due to the lack of high-frequency FOD-event test data in the open literature, a reduced-order turbofan structural model (ROM) was synthesized from a finite element model modal analysis to support the investigation. In addition to providing test data for algorithm development, the ROM is used to determine the optimal sensor location for FOD-event detection. In the presence of significant noise, precise location of the FOD event in time was obtained using the developed wavelet-based feature.

  12. The Role of Inspiratory Muscle Training in Sickle Cell Anemia Related Pulmonary Damage due to Recurrent Acute Chest Syndrome Attacks

    PubMed Central

    Camcıoğlu, Burcu; Boşnak-Güçlü, Meral; Karadallı, Müşerrefe Nur; Akı, Şahika Zeynep; Türköz-Sucak, Gülsan

    2015-01-01

    Background. The sickling of red blood cells causes a constellation of musculoskeletal, cardiovascular, and pulmonary manifestations. A 32-year-old gentleman with sickle cell anemia (SCA) had been suffering from recurrent acute chest syndrome (ACS). Aim. To examine the effects of inspiratory muscle training (IMT) on pulmonary functions, respiratory and peripheral muscle strength, functional exercise capacity, and quality of life in this patient with SCA. Methods. Functional exercise capacity was evaluated using six-minute walk test, respiratory muscle strength using mouth pressure device, hand grip strength using hand-held dynamometer, pain using Visual Analogue Scale, fatigue using Fatigue Severity Scale, dyspnea using Modified Medical Research Council Scale, and health related quality of life using European Organization for Research and Treatment of Cancer QOL measurement. Results. A significant improvement has been demonstrated in respiratory muscle strength, functional exercise capacity, pain, fatigue, dyspnea, and quality of life. There was no admission to emergency department due to acute chest syndrome in the following 12 months after commencing regular erythrocytapheresis. Conclusion. This is the first report demonstrating the beneficial effects of inspiratory muscle training on functional exercise capacity, respiratory muscle strength, pain, fatigue, dyspnea, and quality of life in a patient with recurrent ACS. PMID:26060589

  13. Oxidative damage of U937 human leukemic cells caused by hydroxyl radical results in singlet oxygen formation.

    PubMed

    Rác, Marek; Křupka, Michal; Binder, Svatopluk; Sedlářová, Michaela; Matušková, Zuzana; Raška, Milan; Pospíšil, Pavel

    2015-01-01

    The exposure of human cells to oxidative stress leads to the oxidation of biomolecules such as lipids, proteins and nuclei acids. In this study, the oxidation of lipids, proteins and DNA was studied after the addition of hydrogen peroxide and Fenton reagent to cell suspension containing human leukemic monocyte lymphoma cell line U937. EPR spin-trapping data showed that the addition of hydrogen peroxide to the cell suspension formed hydroxyl radical via Fenton reaction mediated by endogenous metals. The malondialdehyde HPLC analysis showed no lipid peroxidation after the addition of hydrogen peroxide, whereas the Fenton reagent caused significant lipid peroxidation. The formation of protein carbonyls monitored by dot blot immunoassay and the DNA fragmentation measured by comet assay occurred after the addition of both hydrogen peroxide and Fenton reagent. Oxidative damage of biomolecules leads to the formation of singlet oxygen as conformed by EPR spin-trapping spectroscopy and the green fluorescence of singlet oxygen sensor green detected by confocal laser scanning microscopy. It is proposed here that singlet oxygen is formed by the decomposition of high-energy intermediates such as dioxetane or tetroxide formed by oxidative damage of biomolecules.

  14. Oxidative Damage of U937 Human Leukemic Cells Caused by Hydroxyl Radical Results in Singlet Oxygen Formation

    PubMed Central

    Rác, Marek; Křupka, Michal; Binder, Svatopluk; Sedlářová, Michaela; Matušková, Zuzana; Raška, Milan; Pospíšil, Pavel

    2015-01-01

    The exposure of human cells to oxidative stress leads to the oxidation of biomolecules such as lipids, proteins and nuclei acids. In this study, the oxidation of lipids, proteins and DNA was studied after the addition of hydrogen peroxide and Fenton reagent to cell suspension containing human leukemic monocyte lymphoma cell line U937. EPR spin-trapping data showed that the addition of hydrogen peroxide to the cell suspension formed hydroxyl radical via Fenton reaction mediated by endogenous metals. The malondialdehyde HPLC analysis showed no lipid peroxidation after the addition of hydrogen peroxide, whereas the Fenton reagent caused significant lipid peroxidation. The formation of protein carbonyls monitored by dot blot immunoassay and the DNA fragmentation measured by comet assay occurred after the addition of both hydrogen peroxide and Fenton reagent. Oxidative damage of biomolecules leads to the formation of singlet oxygen as conformed by EPR spin-trapping spectroscopy and the green fluorescence of singlet oxygen sensor green detected by confocal laser scanning microscopy. It is proposed here that singlet oxygen is formed by the decomposition of high-energy intermediates such as dioxetane or tetroxide formed by oxidative damage of biomolecules. PMID:25730422

  15. Nucleosomes Suppress the Formation of Double-strand DNA Breaks during Attempted Base Excision Repair of Clustered Oxidative Damages*

    PubMed Central

    Cannan, Wendy J.; Tsang, Betty P.; Wallace, Susan S.; Pederson, David S.

    2014-01-01

    Exposure to ionizing radiation can produce multiple, clustered oxidative lesions in DNA. The near simultaneous excision of nearby lesions in opposing DNA strands by the base excision repair (BER) enzymes can produce double-strand DNA breaks (DSBs). This attempted BER accounts for many of the potentially lethal or mutagenic DSBs that occur in vivo. To assess the impact of nucleosomes on the frequency and pattern of BER-dependent DSB formation, we incubated nucleosomes containing oxidative damages in opposing DNA strands with selected DNA glycosylases and human apurinic/apyrimidinic endonuclease 1. Overall, nucleosomes substantially suppressed DSB formation. However, the degree of suppression varied as a function of (i) the lesion type and DNA glycosylase tested, (ii) local sequence context and the stagger between opposing strand lesions, (iii) the helical orientation of oxidative lesions relative to the underlying histone octamer, and (iv) the distance between the lesion cluster and the nucleosome edge. In some instances the binding of a BER factor to one nucleosomal lesion appeared to facilitate binding to the opposing strand lesion. DSB formation did not invariably lead to nucleosome dissolution, and in some cases, free DNA ends resulting from DSB formation remained associated with the histone octamer. These observations explain how specific structural and dynamic properties of nucleosomes contribute to the suppression of BER-generated DSBs. These studies also suggest that most BER-generated DSBs will occur in linker DNA and in genomic regions associated with elevated rates of nucleosome turnover or remodeling. PMID:24891506

  16. Field observations of seismic velocity changes caused by shaking-induced damage and healing due to mesoscopic nonlinearity

    NASA Astrophysics Data System (ADS)

    Gassenmeier, M.; Sens-Schönfelder, C.; Eulenfeld, T.; Bartsch, M.; Victor, P.; Tilmann, F.; Korn, M.

    2016-03-01

    To investigate temporal seismic velocity changes due to earthquake related processes and environmental forcing in Northern Chile, we analyse 8 yr of ambient seismic noise recorded by the Integrated Plate Boundary Observatory Chile (IPOC). By autocorrelating the ambient seismic noise field measured on the vertical components, approximations of the Green's functions are retrieved and velocity changes are measured with Coda Wave Interferometry. At station PATCX, we observe seasonal changes in seismic velocity caused by thermal stress as well as transient velocity reductions in the frequency range of 4-6 Hz. Sudden velocity drops occur at the time of mostly earthquake-induced ground shaking and recover over a variable period of time. We present an empirical model that describes the seismic velocity variations based on continuous observations of the local ground acceleration. The model assumes that not only the shaking of large earthquakes causes velocity drops, but any small vibrations continuously induce minor velocity variations that are immediately compensated by healing in the steady state. We show that the shaking effect is accumulated over time and best described by the integrated envelope of the ground acceleration over the discretization interval of the velocity measurements, which is one day. In our model, the amplitude of the velocity reduction as well as the recovery time are proportional to the size of the excitation. This model with two free scaling parameters fits the data of the shaking induced velocity variation in remarkable detail. Additionally, a linear trend is observed that might be related to a recovery process from one or more earthquakes before our measurement period. A clear relationship between ground shaking and induced velocity reductions is not visible at other stations. We attribute the outstanding sensitivity of PATCX to ground shaking and thermal stress to the special geological setting of the station, where the subsurface material

  17. Global crop yield reductions due to surface ozone exposure: 1. Year 2000 crop production losses and economic damage

    NASA Astrophysics Data System (ADS)

    Avnery, Shiri; Mauzerall, Denise L.; Liu, Junfeng; Horowitz, Larry W.

    2011-04-01

    Exposure to elevated concentrations of surface ozone (O 3) causes substantial reductions in the agricultural yields of many crops. As emissions of O 3 precursors rise in many parts of the world over the next few decades, yield reductions from O 3 exposure appear likely to increase the challenges of feeding a global population projected to grow from 6 to 9 billion between 2000 and 2050. This study estimates year 2000 global yield reductions of three key staple crops (soybean, maize, and wheat) due to surface ozone exposure using hourly O 3 concentrations simulated by the Model for Ozone and Related Chemical Tracers version 2.4 (MOZART-2). We calculate crop losses according to two metrics of ozone exposure - seasonal daytime (08:00-19:59) mean O 3 (M12) and accumulated O 3 above a threshold of 40 ppbv (AOT40) - and predict crop yield losses using crop-specific O 3 concentration:response functions established by field studies. Our results indicate that year 2000 O 3-induced global yield reductions ranged, depending on the metric used, from 8.5-14% for soybean, 3.9-15% for wheat, and 2.2-5.5% for maize. Global crop production losses totaled 79-121 million metric tons, worth $11-18 billion annually (USD 2000). Our calculated yield reductions agree well with previous estimates, providing further evidence that yields of major crops across the globe are already being substantially reduced by exposure to surface ozone - a risk that will grow unless O 3-precursor emissions are curbed in the future or crop cultivars are developed and utilized that are resistant to O 3.

  18. Thiourea protects against copper-induced oxidative damage by formation of a redox-inactive thiourea-copper complex.

    PubMed

    Zhu, Ben-Zhan; Antholine, William E; Frei, Balz

    2002-06-15

    Although thiourea has been used widely to study the role of hydroxyl radicals in metal-mediated biological damage, it is not a specific hydroxyl radical scavenger and may also exert antioxidant effects unrelated to hydroxyl radical scavenging. Thus, we investigated the effects of thiourea on copper-induced oxidative damage to bovine serum albumin (1 mg/ml) in three different copper-containing systems: Cu(II)/ascorbate, Cu(II)/H(2)O(2), and Cu(II)/H(2)O(2)/ascorbate [Cu(II), 0.1 mM; ascorbate, 1 mM; H(2)O(2), 1 mM]. Oxidative damage to albumin was measured as protein carbonyl formation. Thiourea (0.1-10 mM) provided marked and dose-dependent protection against protein oxidation in all three copper-containing systems. In contrast, only minor protection was observed with dimethyl sulfoxide and mannitol, even at concentrations as high as 100 mM. Strong protection was also observed with dimethylthiourea, but not with urea or dimethylurea. Thiourea also significantly inhibited copper-catalyzed oxidation of ascorbate, and competed effectively with histidine and 1,10-phenanthroline for binding of cuprous, but not cupric, copper, as demonstrated by both UV-visible and low temperature electron spin resonance measurements. We conclude that the protection by thiourea against copper-mediated protein oxidation is not through scavenging of hydroxyl radicals, but rather through the chelation of cuprous copper and the formation of a redox-inactive thiourea-copper complex.

  19. A case of tricuspid valve endocarditis due to Cardiobacterium hominis which emphasizes the shift between the poverty of clinical symptoms and the severity of cardiac damages.

    PubMed

    Molet, Lucie; Revest, Matthieu; Fournet, Maxime; Donal, Erwan; Bonnaure-Mallet, Martine; Minet, Jacques; Le Bars, Hervé

    2016-12-01

    Infectious endocarditis due to Cardiobacterium hominis is an uncommon event, accounting for less than 2% of all cases of infectious endocarditis. The infection of the tricuspid valve as it is reported here is extremely rare. We report the case of a tricuspid endocarditis due to Cardiobacterium hominis in a 56 year-old man who was admitted to hospital with pelvic and scapular pain. The diagnosis was established through positive blood cultures and echographic detection of a large tricuspid vegetation. Despite efficient antibiotic therapy, valve replacement was required. The clinical course of Cardiobacterium endocarditis is usually subacute, and the diagnosis may therefore be delayed. This case emphasizes the shift between the poverty of clinical symptoms and severity of cardiac damages, what we could call the Cardiobacterium paradox.

  20. Radiation-induced damage to cellular DNA: Chemical nature and mechanisms of lesion formation

    NASA Astrophysics Data System (ADS)

    Cadet, Jean; Wagner, J. Richard

    2016-11-01

    This mini-review focuses on the recent identification of several novel radiation-induced single and tandem modifications in cellular DNA. For this purpose accurate high-performance electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) was applied allowing their quantitative measurement and unambiguous characterization. Exposure of human cells to gamma rays led to the formation of several modified bases arising from the rearrangement of the pyrimidine ring of thymine, cytosine and 5-methylcytosine subsequent to initial addition of an hydroxyl radical (•OH) to the 5,6-ethylenic bond. In addition, 5-hydroxymethylcytosine, an novel epigenetic mark, and 5-formylcytosine, were found to be generated consecutively to •OH-mediated hydrogen abstraction from the methyl group of 5-methylcytosine. Relevant mechanistic information on one-oxidation reactions of cellular DNA was also gained from the detection of 5-hydroxycytosine and guanine-thymine intra-strand adducts whose formation is rationalized by the generation of related base radical cation. Attempts to search for the radiation-induced formation of purine 5‧,8-cyclo-2‧-deoxyribonucleosides were unsuccessful with the exception of trace amounts of (5‧S)-5‧,8-cyclo-2‧-deoxyadenosine.

  1. Enhanced Light Emission due to Formation of Semi-polar InGaN/GaN Multi-quantum Wells.

    PubMed

    Zhao, Wan-Ru; Weng, Guo-En; Wang, Jian-Yu; Zhang, Jiang-Yong; Liang, Hong-Wei; Sekiguchi, Takashi; Zhang, Bao-Ping

    2015-12-01

    InGaN/GaN multi-quantum wells (MQWs) are grown on (0001) sapphire substrates by metal organic chemical vapor deposition (MOCVD) with special growth parameters to form V-shaped pits simultaneously. Measurements by atomic force microscopy (AFM) and transmission electron microscopy (TEM) demonstrate the formation of MQWs on both (0001) and ([Formula: see text]) side surface of the V-shaped pits. The latter is known to be a semi-polar surface. Optical characterizations together with theoretical calculation enable us to identify the optical transitions from these MQWs. The layer thickness on ([Formula: see text]) surface is smaller than that on (0001) surface, and the energy level in the ([Formula: see text]) semi-polar quantum well (QW) is higher than in the (0001) QW. As the sample temperature is increased from 15 K, the integrated cathodoluminescence (CL) intensity of (0001) MQWs increases first and then decreases while that of the ([Formula: see text]) MQWs decreases monotonically. The integrated photoluminescence (PL) intensity of (0001) MQWs increases significantly from 15 to 70 K. These results are explained by carrier injection from ([Formula: see text]) to (0001) MQWs due to thermal excitation. It is therefore concluded that the emission efficiency of (0001) MQWs at high temperatures can be greatly improved due to the formation of semi-polar MQWs.

  2. Response of thyroid follicular cells to gamma irradiation compared to proton irradiation. I. Initial characterization of DNA damage, micronucleus formation, apoptosis, cell survival, and cell cycle phase redistribution

    NASA Technical Reports Server (NTRS)

    Green, L. M.; Murray, D. K.; Bant, A. M.; Kazarians, G.; Moyers, M. F.; Nelson, G. A.; Tran, D. T.

    2001-01-01

    The RBE of protons has been assumed to be equivalent to that of photons. The objective of this study was to determine whether radiation-induced DNA and chromosome damage, apoptosis, cell killing and cell cycling in organized epithelial cells was influenced by radiation quality. Thyroid-stimulating hormone-dependent Fischer rat thyroid cells, established as follicles, were exposed to gamma rays or proton beams delivered acutely over a range of physical doses. Gamma-irradiated cells were able to repair DNA damage relatively rapidly so that by 1 h postirradiation they had approximately 20% fewer exposed 3' ends than their counterparts that had been irradiated with proton beams. The persistence of free ends of DNA in the samples irradiated with the proton beam implies that either more initial breaks or a quantitatively different type of damage had occurred. These results were further supported by an increased frequency of chromosomal damage as measured by the presence of micronuclei. Proton-beam irradiation induced micronuclei at a rate of 2.4% per gray, which at 12 Gy translated to 40% more micronuclei than in comparable gamma-irradiated cultures. The higher rate of micronucleus formation and the presence of larger micronuclei in proton-irradiated cells was further evidence that a qualitatively more severe class of damage had been induced than was induced by gamma rays. Differences in the type of damage produced were detected in the apoptosis assay, wherein a significant lag in the induction of apoptosis occurred after gamma irradiation that did not occur with protons. The more immediate expression of apoptotic cells in the cultures irradiated with the proton beam suggests that the damage inflicted was more severe. Alternatively, the cell cycle checkpoint mechanisms required for recovery from such damage might not have been invoked. Differences based on radiation quality were also evident in the alpha components of cell survival curves (0.05 Gy(-1) for gamma rays, 0

  3. Response of thyroid follicular cells to gamma irradiation compared to proton irradiation. I. Initial characterization of DNA damage, micronucleus formation, apoptosis, cell survival, and cell cycle phase redistribution

    NASA Technical Reports Server (NTRS)

    Green, L. M.; Murray, D. K.; Bant, A. M.; Kazarians, G.; Moyers, M. F.; Nelson, G. A.; Tran, D. T.

    2001-01-01

    The RBE of protons has been assumed to be equivalent to that of photons. The objective of this study was to determine whether radiation-induced DNA and chromosome damage, apoptosis, cell killing and cell cycling in organized epithelial cells was influenced by radiation quality. Thyroid-stimulating hormone-dependent Fischer rat thyroid cells, established as follicles, were exposed to gamma rays or proton beams delivered acutely over a range of physical doses. Gamma-irradiated cells were able to repair DNA damage relatively rapidly so that by 1 h postirradiation they had approximately 20% fewer exposed 3' ends than their counterparts that had been irradiated with proton beams. The persistence of free ends of DNA in the samples irradiated with the proton beam implies that either more initial breaks or a quantitatively different type of damage had occurred. These results were further supported by an increased frequency of chromosomal damage as measured by the presence of micronuclei. Proton-beam irradiation induced micronuclei at a rate of 2.4% per gray, which at 12 Gy translated to 40% more micronuclei than in comparable gamma-irradiated cultures. The higher rate of micronucleus formation and the presence of larger micronuclei in proton-irradiated cells was further evidence that a qualitatively more severe class of damage had been induced than was induced by gamma rays. Differences in the type of damage produced were detected in the apoptosis assay, wherein a significant lag in the induction of apoptosis occurred after gamma irradiation that did not occur with protons. The more immediate expression of apoptotic cells in the cultures irradiated with the proton beam suggests that the damage inflicted was more severe. Alternatively, the cell cycle checkpoint mechanisms required for recovery from such damage might not have been invoked. Differences based on radiation quality were also evident in the alpha components of cell survival curves (0.05 Gy(-1) for gamma rays, 0

  4. Response of thyroid follicular cells to gamma irradiation compared to proton irradiation. I. Initial characterization of DNA damage, micronucleus formation, apoptosis, cell survival, and cell cycle phase redistribution.

    PubMed

    Green, L M; Murray, D K; Bant, A M; Kazarians, G; Moyers, M F; Nelson, G A; Tran, D T

    2001-01-01

    The RBE of protons has been assumed to be equivalent to that of photons. The objective of this study was to determine whether radiation-induced DNA and chromosome damage, apoptosis, cell killing and cell cycling in organized epithelial cells was influenced by radiation quality. Thyroid-stimulating hormone-dependent Fischer rat thyroid cells, established as follicles, were exposed to gamma rays or proton beams delivered acutely over a range of physical doses. Gamma-irradiated cells were able to repair DNA damage relatively rapidly so that by 1 h postirradiation they had approximately 20% fewer exposed 3' ends than their counterparts that had been irradiated with proton beams. The persistence of free ends of DNA in the samples irradiated with the proton beam implies that either more initial breaks or a quantitatively different type of damage had occurred. These results were further supported by an increased frequency of chromosomal damage as measured by the presence of micronuclei. Proton-beam irradiation induced micronuclei at a rate of 2.4% per gray, which at 12 Gy translated to 40% more micronuclei than in comparable gamma-irradiated cultures. The higher rate of micronucleus formation and the presence of larger micronuclei in proton-irradiated cells was further evidence that a qualitatively more severe class of damage had been induced than was induced by gamma rays. Differences in the type of damage produced were detected in the apoptosis assay, wherein a significant lag in the induction of apoptosis occurred after gamma irradiation that did not occur with protons. The more immediate expression of apoptotic cells in the cultures irradiated with the proton beam suggests that the damage inflicted was more severe. Alternatively, the cell cycle checkpoint mechanisms required for recovery from such damage might not have been invoked. Differences based on radiation quality were also evident in the alpha components of cell survival curves (0.05 Gy(-1) for gamma rays, 0

  5. Inhibition of Hsp90 acts synergistically with topoisomerase II poisons to increase the apoptotic killing of cells due to an increase in topoisomerase II mediated DNA damage

    PubMed Central

    Barker, Catherine R.; McNamara, Anne V.; Rackstraw, Stephen A.; Nelson, David E.; White, Mike R.; Watson, Alastair J. M.; Jenkins, John R.

    2006-01-01

    Topoisomerase II plays a crucial role during chromosome condensation and segregation in mitosis and meiosis and is a highly attractive target for chemotherapeutic agents. We have identified previously topoisomerase II and heat shock protein 90 (Hsp90) as part of a complex. In this paper we demonstrate that drug combinations targeting these two enzymes cause a synergistic increase in apoptosis. The objective of our study was to identify the mode of cell killing and the mechanism behind the increase in topoisomerase II mediated DNA damage. Importantly we demonstrate that Hsp90 inhibition results in an increased topoiosmerase II activity but not degradation of topoisomerase II and it is this, in the presence of a topoisomerase II poison that causes the increase in cell death. Our results suggest a novel mechanism of action where the inhibition of Hsp90 disrupts the Hsp90–topoisomerase II interaction leading to an increase in and activation of unbound topoisomerase II, which, in the presence of a topoisomerase II poison leads to the formation of an increased number of cleavable complexes ultimately resulting in rise in DNA damage and a subsequent increase cell death. PMID:16504968

  6. Authigenic albite formation due to water-rock interactions - Case study: Magnus oilfield (UK, Northern North Sea)

    NASA Astrophysics Data System (ADS)

    Mu, Nana; Fu, Yunjiao; Schulz, Hans-Martin; van Berk, Wolfgang

    2016-01-01

    It is the aim of this contribution to test whether organic-inorganic interactions could induce the formation of authigenic albite. This concept and related results are being compared with modelling scenarios which are purely based on inorganic geochemical reactions. In order to unravel the pathway of authigenic albite formation, this paper presents results of a multidisciplinary study from imaging, geochemistry, mineralogy, and hydrogeochemical modelling. The Jurassic reservoir sandstones of the Magnus oilfield (UK, North Sea) were chosen as a test site. Albite occurs with 4-18 wt.% in the Magnus sandstones and its contents vary with depth. However, albite contents increase with increasing K-feldspar contents and decreasing grain size. It occurs in three forms: (1) as lamellae in perthite, (2) as overgrowth on/in corroded feldspar, and, (3) as cloudy replacing albite patches in K-feldspar. The albite overgrowth has the highest chemical purity (100% albite) whilst albite lamellae and replacing albite patches are slightly less pure (containing 1-4% anorthite). Albite appears non-altered, and has a euhedral morphology and dull cathodoluminescence. It commonly co-occurs with corroded K-feldspar grains. The precipitation of diagenetic albite in the Magnus sandstones is attributed to deep burial 80 Ma ago and may have continued until today at temperatures between 90-120 °C. The results of hydrogeochemical modelling offer two possible pathways for the authigenic albite formation: (1) Dissolution of unstable minerals (such as kaolinite and chalcedony) coupled to reduction of ferric iron minerals by products generated during oil generation, migration and degradation; (2) Dissolution of non-end member feldspar, such as K-feldspar with 10% albite, coupled to illite formation can account for trace amounts of albite due to an elevated Na+/K+ activity ratio in the pore water.

  7. Heat-induced formation of reactive oxygen species and 8-oxoguanine, a biomarker of damage to DNA

    PubMed Central

    Bruskov, Vadim I.; Malakhova, Lyudmila V.; Masalimov, Zhaksylyk K.; Chernikov, Anatoly V.

    2002-01-01

    Heat-induced formation of 8-oxoguanine was demonstrated in DNA solutions in 10–3 M phosphate buffer, pH 6.8, by enzyme-linked immunosorbent assays using monoclonal antibodies against 8-oxoguanine. A radiation-chemical yield of 3.7 × 10–2 µmol J–1 for 8-oxoguanine production in DNA upon γ-irradiation was used as an adequate standard for quantitation of 8-oxoguanine in whole DNA. The initial yield of heat-induced 8-oxoguanine exhibits first order kinetics. The rate constants for 8-oxoguanine formation were determined at elevated temperatures; the activation energy was found to be 27 ± 2 kcal/mol. Extrapolation to 37°C gave a value of k37 = 4.7 × 10–10 s–1. Heat-induced 8-oxoguanine formation and depurination of guanine and adenine show similarities of the processes, which implies that heat-mediated generation of reactive oxygen species (ROS) should occur. Heat-induced production of H2O2 in phosphate buffer was shown. The sequence of reactions of thermally mediated ROS formation have been established: activation of dissolved oxygen to the singlet state, generation of superoxide radicals and their dismutation to H2O2. Gas saturation (O2, N2 and Ar), D2O, scavengers of 1O2, O2–• and OH• radicals and metal chelators influenced heat-induced 8-oxoguanine formation as they affected thermal ROS generation. These findings imply that heat acts via ROS attack leading to oxidative damage to DNA. PMID:11884633

  8. Acoustic Emission Activity and Spatial Distribution of Damage Associated with Compaction Band Formation

    NASA Astrophysics Data System (ADS)

    Baud, P.; Klein, E.; Wong, T.

    2001-12-01

    Compaction band has been observed as a localized failure mode in porous sandstones, at stress states that are associated with the transitional regime from brittle faulting to distributed cataclastic flow. Detailed microstructural observations were conducted on the Bentheim, Berea, Boise, Darley Dale and Rothbach sandstones with porosities ranging from 13% to 35% to delineate and quantify the spatial distribution of damage associated with the development of compaction bands. Significant grain crushing and porosity reduction are evident in the localized bands, with crack densities up to 5 times greater than those in areas outside the bands. Two different patterns of strain localization can be distinguished: diffuse conjugate shears at relatively high angles, and discrete compaction bands subperpendicular to the maximum compression direction. Whereas the development of diffuse bands is characterized by the continuous accumulation of acoustic emissions (AE), discrete bands are associated with episodic surges in AE that are characterized by an overall strain hardening trend punctuated by episodic stress drops. The number of discrete bands correlates with the number of AE surges and stress drops. Preliminary permeability measurements indicate appreciable reductions of permeability during compaction band development.

  9. Large-diameter coiled tubing completions decrease risk of formation damage

    SciTech Connect

    Norton, V. ); Edens, F. ); Coker, G. ); King, G. )

    1992-07-20

    Amoco Production Co. has used large-diameter coiled tubing strings to avoid damaging gas wells with kill fluids. The coiled tubing is stripped in the gas well under pressure. In Amoco's case, the gas flows up the tubing/casing annulus. The coiled tubing string provides a way to blow down the well whenever the well loads up with liquids from completion, workover, or naturally produced fluids. This paper reports that to date, Amoco has installed coiled tubing in four wells. The oldest has 18 months of service. Although some turbine longevity questions must be answered, the first four completions have proven fast and trouble free. The basic equipment for handling coil tubing is shown. The transport trailer and tubing injector head are similar to standard servicing equipment and not considered experimental. The production tubing reel is capable of carrying 14,000 ft of 2-in tubing or 18,000 ft of 1 3/4-in. tubing. For shallower wells, multiple tubing strings can be would on the same spool. Because of handling difficulties of large tubing, spools must be wound at the factory. Most of the largest sizes are made to order, making lead time a necessary consideration.

  10. Process of cortical network formation and impact of early brain damage.

    PubMed

    Kiss, Jozsef Z; Vasung, Lana; Petrenko, Volodymyr

    2014-04-01

    The aim is to review mechanisms that are central to the formation of proper cortical circuitry and relevant to perinatal brain injury and premature birth. Clinical investigations using noninvasive imaging techniques suggest that impaired connectivity of cortical circuitry is associated with perinatal adverse conditions. Recent experimental and translational studies revealed developmental mechanisms that are critical for circuit formation and potentially at risk in the perinatal period. These include existence of last wave genesis, migration and integration of gamma-aminobutyric acid (GABA) interneurons in the perinatal period; maturation of GABA interneuron networks that are central to critical period plasticity; transient connections by subplate neurons that guide thalamocortical connectivity, and a perineuronal microglia network that maintains axonal growth and neuronal survival as well as executing synaptic pruning. In addition, recent work has demonstrated that birth plays a key role in triggering the maturation cascade of cortical circuits. Altered maturation of cortical circuits is an increasingly recognized aspect of perinatal injury and premature birth. Potential mechanisms are revealed but further translational studies are required to associate fine changes at the cellular and molecular level with imaging data in experimental models.

  11. Spermine participates in oxidative damage of guanosine and 8-oxoguanosine leading to deoxyribosylurea formation.

    PubMed

    Hosford, Mandy E; Muller, James G; Burrows, Cynthia J

    2004-08-11

    Oxidation of single- or double-stranded DNA containing a 7,8-dihydro-8-oxoguanosine lesion with the one-electron oxidant Na2IrCl6 in the presence of spermine led to formation of a covalent adduct that was analyzed by gel electrophoresis, HPLC, ESI-MS, and UV-vis. The adduct was labile to heat, exhibiting a t1/2 of 12 h at 37 degrees C, and the ultimate hydrolysis product was characterized as a deoxyribosylurea lesion. Data from model studies with 1,3-diaminopropane vs 1,4-diaminobutane are consistent with initial formation of a C5 spermine adduct from a dehydro-8-oxoguanosine intermediate, followed by rearrangement to a spiroaminal subject to slow hydrolysis at C4 of the purine. Spermine adducts could also be formed from oxidation of the analogous G-containing oligomer from reaction with singlet oxygen, albeit in lower yield. These results are surprising in light of the traditional view that spermine is radioprotective against DNA oxidation.

  12. THEOS-2 Orbit Design: Formation Flying in Equatorial Orbit and Damage Prevention Technique for the South Atlantic Magnetic Anomaly (SAMA)

    NASA Astrophysics Data System (ADS)

    Pimnoo, Ammarin

    2016-07-01

    Geo-Informatics and Space Technology Development Agency (GISTDA) has initiative THEOS-2 project after the THEOS-1 has been operated for more than 7 years which is over the lifetime already. THEOS-2 project requires not only the development of earth observation satellite(s), but also the development of the area-based decision making solution platform comprising of data, application systems, data processing and production system, IT infrastructure improvement and capacity building through development of satellites, engineering model, and infrastructures capable of supporting research in related fields. The developing satellites in THEOS-2 project are THAICHOTE-2 and THAICHOTE-3. This paper focuses the orbit design of THAICHOTE-2 & 3. It discusses the satellite orbit design for the second and third EOS of Thailand. In this paper, both THAICHOTE will be simulated in an equatorial orbit as a formation flying which will be compared the productive to THAICHOTE-1 (THEOS-1). We also consider a serious issue in equatorial orbit design, namely the issue of the geomagnetic field in the area of the eastern coast of South America, called the South Atlantic Magnetic Anomaly (SAMA). The high-energy particles of SAMA comprise a radiation environment which can travel through THAICHOTE-2 & 3 material and deposit kinetic energy. This process causes atomic displacement or leaves a stream of charged atoms in the incident particles' wake. It can cause damage to the satellite including reduction of power generated by solar arrays, failure of sensitive electronics, increased background noise in sensors, and exposure of the satellite devices to radiation. This paper demonstrates the loss of ionizing radiation damage and presents a technique to prevent damage from high-energy particles in the SAMA.

  13. Indoor damage of aged porous natural stone due to thermohygric stress: a case study of opuka stone altar from the St. Vitus Cathedral, Prague (Czech Republic)

    NASA Astrophysics Data System (ADS)

    Prikryl, Richard; Prikrylova, Jirina; Racek, Martin; Kreislova, Kateřina; Weishauptova, Zuzana

    2016-04-01

    Opuka stone (extremely fine-grained clayey-calcareous silicite) used for a carved stone altar located in the interior of the St. Vitus Cathedral (Prague, Czech Republic) was affected by decay phenomena (formation of the case-hardened surface, its later blistering, flaking and/or powdering of stone substrate) which are similar to those observed in outdoor environments. Through the detailed analytical study (optical microscopy and scanning electron microscopy with energy dispersive spectrometry and x-ray elemental mapping of cross-sections of surface layers, x-ray diffraction of surface layers, ion-exchange chromatography for water-soluble salts, mercury porosimetry) and analysis of long-term indoor environmental monitoring (temperature, relative humidity, sulphur and nitrogen oxides deposition), it has been found that observed decay phenomena, which are manifested on microscale by brittle damage and formation of mode I (tensile) cracks along the exposed surface of the stone, can be interpreted as a result from thermohygric stress occurring on the interface between case hardened surface layer and stone substrate.

  14. Pseudotumour formation due to tribocorrosion at the taper interface of large diameter metal on polymer modular total hip replacements.

    PubMed

    Cook, Richard B; Bolland, Benjamin J R F; Wharton, Julian A; Tilley, Simon; Latham, Jeremy M; Wood, Robert J K

    2013-09-01

    We present an in-depth failure analysis of two large diameter bearing metal-on-polymer (MoP) modular total hip replacements, which have required revision surgery due to pseudotumour formation. The failure analysis showed a discrete pattern of material loss from the distal end of the head taper/stem trunnion interface. We postulate that the use of a proximal contacting taper design had provided insufficient mechanical locking between the head and the stem, enabling the head to toggle on the trunnion. In addition, the difference in angle between the taper and the trunnion formed a crevice between the two components. Through a combination of crevice environment, mechanically assisted corrosion, mechanical wear and erosion; debris and metal-ions have been released resulting in the adverse local tissue reactions (ALTR).

  15. Analysis of the internal structure of a carbonate damage zone: Implications for the mechanisms of fault breccia formation and fluid flow

    NASA Astrophysics Data System (ADS)

    Hausegger, Stefan; Kurz, Walter; Rabitsch, Robert; Kiechl, Eva; Brosch, Franz-Josef

    2010-09-01

    A segment of the Salzach-Ennstal fault zone (Talhof fault, Eastern Alps) shows evidence for joint nucleation by layer-parallel shear, causing the formation of joint-bounded slices oriented at high angles (65-85°) with respect to the shear zone boundary (SZB). Subsequent slice rotation resulted in joint reactivation as antithetic shears, slice kinking, and breaking-up of the individual slices into smaller fragments. The latter process, due to the longitudinal constraint of slices with impeded shear zone widening, marked the transition to cataclasite formation and fault core evolution during shear localization. Cataclasites were subsequently cemented and underwent continuous shear deformation by re-fracturing. Cement precipitation from fluids therefore played a fundamental role in the evolution of the fault zone, with a cyclic change between an open and a closed permeability system during fault evolution. Stable isotope compositions (δ 13C, δ 18O) of fault rock cements indicate a continuous equilibration between protolith-derived fragments and cements precipitated from those fluids. This points to limited fluid amounts, only temporally replenished by meteoric water, and a hydraulic gradient that directed fluid flow from the damage zone towards the fault core.

  16. Role of base damage in aberration formation: interaction of aphidicolin and x-rays

    SciTech Connect

    Bender, M.A.; Preston, R.J.

    1981-01-01

    The base analog cytosine arabinoside (CA) is an inhibitor of DNA synthesis that is able to induce chromosomal aberrations not only in the DNA synthetic (S) phase of the cell cycle but in cells in the pre- (G/sub 0/ or G/sub 1/) and in the post-DNA-synthetic (G/sub 2/) phases of the cell cycle as well. Incubation of human peripheral lymphocytes in CA following either G/sub 0/ or G/sub 2/ x irradiation causes a synergistic increase in chromosomal aberration frequency. CA is believed to preferentially inhibit DNA polymerase ..cap alpha... It is suggested that it is inhibition of the repair of x-ray-induced base damage that is responsible for the synergistic effect on chromosomal aberration production observed with x-ray and CA treatment of human peripheral lymphocytes. It has also been observed that CA induces sister chromatid exchanges (SCE) in mammalian cells when present during normal DNA replication and that it also interacts synergistically with uv in the induction of SCE. A number of other inhibitors of DNA synthesis were also tested, one, aphidicolin (APC), did produce effects similar to CA at the same concentration. Aphidicolin is a tetracyclic diterpinoid that inhibits the growth of eukaryotic cells by inhibition of DNA synthesis. This action has been shown to result from specific inhibition of DNA polymerase ..cap alpha.., but not of polymerases ..beta.. or ..gamma... Unlike CA, it seems likely that APC inhibits by binding to and inactivating the DNA-..cap alpha.. polymerase complex. Because both CA and APC are ..cap alpha.. polymerase inhibitors and because both interact synergistically with uv in the production of SCE, studies were conducted to determine whether APC also shares other cytogenetic properties of CA. Results to date have shown that, like CA, APC is clastogenic in both G/sub 0/ and G/sub 2/, and it also interacts synergistically with x rays to increase chromosomal aberration production in both G/sub 0/ and G/sub 2/. (ERB)

  17. A giant and insidious subphrenic biloma formation due to gallbladder perforation mimicking biliary cystic tumor: A case report

    PubMed Central

    Ji, Guwei; Zhu, Feipeng; Wang, Ke; Jiao, Chenyu; Shao, Zicheng; Li, Xiangcheng

    2017-01-01

    Gallbladder perforation (GBP) represents a rare, but potentially life-threatening, complication of acute cholecystitis. GBP is subdivided into three categories whereas the development of biloma is extremely rare. The present case study reports on a 40-year-old man with a 10-year history of calculus cholecystitis, who was referred to The First Affiliated Hospital of Nanjing Medical University (Nanjing, China) for the surgical treatment of an emerging massive hepatic entity with insidious symptoms and normal laboratory tests. A preoperative imaging study demonstrated the collection with internal septations and mural nodules, but no visible communication with the biliary system. Given the suspected biliary cystic tumor, a laparotomy was performed and the lumen was scattered with papillae. An intraoperative frozen section examination illustrated a simple hepatic cyst. Biochemical analysis of the collection and histopathology of the gallbladder and capsule substantiated the diagnosis of biloma formation due to GBP. The purpose of the present case report was to demonstrate how a pinhole-sized perforation with extravasation of unconcentrated bile from the gallbladder may result in insidious clinical presentation and an undetected leak site. According to the clinicopathological characteristics and composition, formation of biloma should be classified as type IV GBP. To differentiate bilomas with intracystic septations and mural nodules from BCTs is difficult via a preoperative examination, and the definitive diagnosis should be based on a histological examination. Laparotomy with frozen section examination may be the optimal approach in such a case. PMID:28123732

  18. Influence of subcascade formation on displacement damage at high PKA energies

    SciTech Connect

    Stoller, R.E.; Greenwood, L.R.

    1997-08-01

    The design of first generation fusion reactors will have to be rely on radiation effects data obtained from experiments conducted in fission reactors. Two issues must be addressed to use this data with confidence. The first is differences in the neutron energy spectrum, and the second is differences in nuclear transmutation rates. Differences in the neutron energy spectra are reflected in the energy spectra of the primary knockon atoms (PKA). The issue of PKA energy effects has been addressed through the use of displacement cascade simulations using the method of molecular dynamics (MD). Although MD simulations can provide a detailed picture of the formation and evolution of displacement cascades, they impose a substantial computational burden. However, recent advances in computing equipment permit the simulation of high energy displacement events involving more than one-million atoms; the results presented here encompass MD cascade simulation energies from near the displacement threshold to as high as 40 keV. Two parameters have been extracted from the MD simulations: the number of point defects that remain after the displacement event is completed and the fraction of the surviving interstitials that are contained in clusters. The MD values have been normalized to the number of atomic displacements calculated with the secondary displacement model by Norgett, Robinson, and Torrens (NRT).

  19. Investigation of mud density and weighting materials effect on drilling fluid filter cake properties and formation damage

    NASA Astrophysics Data System (ADS)

    Fattah, K. A.; Lashin, A.

    2016-05-01

    Drilling fluid density/type is an important factor in drilling and production operations. Most of encountered problems during rotary drilling are related to drilling mud types and weights. This paper aims to investigate the effect of mud weight on filter cake properties and formation damage through two experimental approaches. In the first approach, seven water-based drilling fluid samples with same composition are prepared with different densities (9.0-12.0 lb/gal) and examined to select the optimum mud weight that has less damage. The second approach deals with investigating the possible effect of the different weighting materials (BaSO4 and CaCO3) on filter cake properties. High pressure/high temperature loss tests and Scanning Electron Microscopy (SEM) analyses were carried out on the filter cake (two selected samples). Data analysis has revealed that mud weigh of 9.5 lb/gal has the less reduction in permeability of ceramic disk, among the seven used mud densities. Above 10.5 ppg the effect of the mud weight density on formation damage is stabilized at constant value. Fluids of CaCO3-based weighting material, has less reduction in the porosity (9.14%) and permeability (25%) of the filter disk properties than the BaSO4-based fluid. The produced filter cake porosity increases (from 0.735 to 0.859) with decreasing of fluid density in case of drilling samples of different densities. The filtration loss tests indicated that CaCO3 filter cake porosity (0.52) is less than that of the BaSO4 weighted material (0.814). The thickness of the filter cake of the BaSO4-based fluid is large and can cause some problems. The SEM analysis shows that some major elements do occur on the tested samples (Ca, Al, Si, and Ba), with dominance of Ca on the expense of Ba for the CaCO3 fluid sample and vice versa. The less effect of 9.5 lb/gal mud sample is reflected in the well-produced inter-particle pore structure and relatively crystal size. A general recommendation is given to

  20. Cloning, localization and focus formation at DNA damage sites of canine Ku70.

    PubMed

    Koike, Manabu; Yutoku, Yasutomo; Koike, Aki

    2017-03-23

    Understanding the molecular mechanisms of DNA double-strand break (DSB) repair machinery, specifically non-homologous DNA-end joining (NHEJ), is crucial for developing next-generation radiotherapies and common chemotherapeutics for human and animal cancers. The localization, protein-protein interactions and post-translational modifications of core NHEJ factors, might play vital roles for regulation of NHEJ activity. The human Ku heterodimer (Ku70/Ku80) is a core NHEJ factor in the NHEJ pathway and is involved in sensing of DSBs. Companion animals, such as canines, have been proposed to be an excellent model for cancer research, including development of chemotherapeutics. However, the post-translational modifications, localization and complex formation of canine Ku70 have not been clarified. Here, we show that canine Ku70 localizes in the nuclei of interphase cells and that it is recruited quickly at laser-microirradiated DSB sites. Structurally, two DNA-PK phosphorylation sites (S6 and S51), an ubiquitination site (K114), two canonical sumoylation consensus motifs, a CDK phosphorylation motif, and a nuclear localization signal (NLS) in the human Ku70 are evolutionarily conserved in canine and mouse species, while the acetylation sites in human Ku70 are partially conserved. Intriguingly, the primary candidate nucleophile (K31) required for 5'dRP/AP lyase activity of human and mouse Ku70 is not conserved in canines, suggesting that canine Ku does not possess this activity. Our findings provide insights into the molecular mechanisms of Ku-dependent NHEJ in a canine model and form a platform for the development of next-generation common chemotherapeutics for human and animal cancers.

  1. Cloning, localization and focus formation at DNA damage sites of canine Ku70

    PubMed Central

    KOIKE, Manabu; YUTOKU, Yasutomo; KOIKE, Aki

    2017-01-01

    Understanding the molecular mechanisms of DNA double-strand break (DSB) repair machinery, specifically non-homologous DNA-end joining (NHEJ), is crucial for developing next-generation radiotherapies and common chemotherapeutics for human and animal cancers. The localization, protein-protein interactions and post-translational modifications of core NHEJ factors, might play vital roles for regulation of NHEJ activity. The human Ku heterodimer (Ku70/Ku80) is a core NHEJ factor in the NHEJ pathway and is involved in sensing of DSBs. Companion animals, such as canines, have been proposed to be an excellent model for cancer research, including development of chemotherapeutics. However, the post-translational modifications, localization and complex formation of canine Ku70 have not been clarified. Here, we show that canine Ku70 localizes in the nuclei of interphase cells and that it is recruited quickly at laser-microirradiated DSB sites. Structurally, two DNA-PK phosphorylation sites (S6 and S51), an ubiquitination site (K114), two canonical sumoylation consensus motifs, a CDK phosphorylation motif, and a nuclear localization signal (NLS) in the human Ku70 are evolutionarily conserved in canine and mouse species, while the acetylation sites in human Ku70 are partially conserved. Intriguingly, the primary candidate nucleophile (K31) required for 5’dRP/AP lyase activity of human and mouse Ku70 is not conserved in canines, suggesting that canine Ku does not possess this activity. Our findings provide insights into the molecular mechanisms of Ku-dependent NHEJ in a canine model and form a platform for the development of next-generation common chemotherapeutics for human and animal cancers. PMID:28163277

  2. Morphostructural Damage in Food-Spoiling Bacteria due to the Lemon Grass Oil and Its Vapour: SEM, TEM, and AFM Investigations

    PubMed Central

    Tyagi, Amit Kumar; Malik, Anushree

    2012-01-01

    In this study, antimicrobial activity and morphostructural damages due to lemon grass oil (LGO) and its vapour (LGOV) against Escherichia coli strains were investigated. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of LGO were determined by broth-dilution method to be 0.288 mg/mL and 0.567 mg/mL, respectively. Furthermore, the zone of inhibition (45 mm) due to the vapour phase antimicrobial efficacy evaluated using disc volatilization assay was compared with that using disc diffusion assay (i.e., 13.5 mm for the same dose of oil). The morphological and ultrastructural alterations in LGO- and LGOV-treated E. coli cells were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic-force microscopy (AFM). In SEM observation, LGO-treated cells appeared to be aggregated and partially deformed, while LGOV-treated cells lost their turgidity, and the cytoplasmic material completely leaked from the cells. In TEM observation, extensive intracytoplasmic changes and various abnormalities were observed in LGOV-treated cells more than LGO-treated cells. Significant variations in the height and root mean square values of untreated, LGO-, and LGOV-treated E. coli cells were noticed by AFM. Present results indicate that LGO is highly effective against E. coli in vapour phase. PMID:23082083

  3. Decreased Xylitol Formation during Xylose Fermentation in Saccharomyces cerevisiae Due to Overexpression of Water-Forming NADH Oxidase

    PubMed Central

    Zhang, Guo-Chang; Ding, Wen-Tao

    2012-01-01

    The recombinant xylose-fermenting Saccharomyces cerevisiae strain harboring xylose reductase (XR) and xylitol dehydrogenase (XDH) from Scheffersomyces stipitis requires NADPH and NAD+, creates cofactor imbalance, and causes xylitol accumulation during growth on d-xylose. To solve this problem, noxE, encoding a water-forming NADH oxidase from Lactococcus lactis driven by the PGK1 promoter, was introduced into the xylose-utilizing yeast strain KAM-3X. A cofactor microcycle was set up between the utilization of NAD+ by XDH and the formation of NAD+ by water-forming NADH oxidase. Overexpression of noxE significantly decreased xylitol formation and increased final ethanol production during xylose fermentation. Under xylose fermentation conditions with an initial d-xylose concentration of 50 g/liter, the xylitol yields for of KAM-3X(pPGK1-noxE) and control strain KAM-3X were 0.058 g/g xylose and 0.191 g/g, respectively, which showed a 69.63% decrease owing to noxE overexpression; the ethanol yields were 0.294 g/g for KAM-3X(pPGK1-noxE) and 0.211 g/g for the control strain KAM-3X, which indicated a 39.33% increase due to noxE overexpression. At the same time, the glycerol yield also was reduced by 53.85% on account of the decrease in the NADH pool caused by overexpression of noxE. PMID:22156411

  4. Formation of Island Arc-Trench System due to Plate Subduction on the Basis of Elastic Dislocation Theory

    NASA Astrophysics Data System (ADS)

    Fukahata, Y.; Matsu'ura, M.

    2015-12-01

    The most conspicuous cumulative deformation in subduction zones is the formation of island arc-trench system. A pair of anomalies in topography and free-air gravity, high in the arc and low around the trench, is observed without exceptions all over the world. Since the 1960s, elastic dislocation theory has been widely used to interpret coseismic crustal deformation. For the modeling of longer-term crustal deformation, it is necessary to consider viscoelastic properties of the asthenosphere. By simply applying elastic-viscoelastic dislocation theory to plate subduction, Matsu'ura and Sato (1989, GJI) have shown that some crustal deformation remains after the completion of one earthquake cycle, which means that crustal deformation accumulates with time in a long term due to plate subduction. In fact, by constructing a plate interface model in and around Japan, Hashimoto, Fukui and Matsu'ura (2004, PAGEOPH) have demonstrated that the computed vertical displacements due to steady plate subduction well explain the observed free-air gravity anomaly pattern. Recently, we got a lucid explanation of crustal deformation due to plate subduction. In subduction zones, oceanic plates bend and descend into the mantle. Because the bending of oceanic plates is usually not spontaneous, there exists kinematic interaction between the oceanic and overriding plates, which causes cumulative deformation of the overriding plate. This may be understood based on the law of action and reaction: one is bending of an oceanic plate and the other is deformation of the overriding plate. As a special case, it is useful to consider plate subduction along a part of true circle. In this case, crustal deformation due to steady subduction is solely caused by the effect of gravity, because dislocation along a circle does not cause any intrinsic internal deformation. When an oceanic plate is descending along an arcuate plate interface from the right-hand side, according to dislocation theory, the oceanic

  5. Formation of fold and thrust belts on Venus due to horizontal shortening of a laterally heterogeneous lithosphere

    NASA Technical Reports Server (NTRS)

    Zuber, M. T.; Parmentier, E. M.; Neumann, G. A.

    1994-01-01

    An outstanding question relevant to understanding the tectonics of Venus is the mechanism of formation of fold and thrust belts, such as the mountain belts that surround Lakshmi Planum in western Ishtar Terra. These structures are typically long (hundreds of km) and narrow (many tens of km), and are often located at the margins of relatively high (km-scale) topographic rises. Previous studies have attempted to explain fold and thrust belts in various areas of Venus in the context of viscous and brittle wedge theory. However, while wedge theory can explain the change in elevation from the rise to the adjacent lowland, it fails to account for a fundamental aspect of the deformation, i.e., the topographic high at the edge of the rise. In this study we quantitatively explore the hypothesis that fold and thrust belt morphology on Venus can alternatively be explained by horizontal shortening of a lithosphere that is laterally heterogeneous, due either to a change in thickness of the lithosphere or the crust. Lateral heterogeneities in lithosphere structure may arise in response to thermal thinning or extensive faulting, while variations in crustal thickness may arise due to either spatially variable melting of mantle material or by horizontal shortening of the crust. In a variable thickness lithosphere or crust that is horizontally shortened, deformation will tend to localize in the vicinity of thickness heterogeneity, resulting in a higher component of dynamic topography there as compared to elsewhere in the shortening lithosphere. This mechanism may thus provide a simple explanation for the topographic high at the edge of the rise.

  6. Predicting Formation Damage in Aquifer Thermal Energy Storage Systems Utilizing a Coupled Hydraulic-Thermal-Chemical Reservoir Model

    NASA Astrophysics Data System (ADS)

    Müller, Daniel; Regenspurg, Simona; Milsch, Harald; Blöcher, Guido; Kranz, Stefan; Saadat, Ali

    2014-05-01

    In aquifer thermal energy storage (ATES) systems, large amounts of energy can be stored by injecting hot water into deep or intermediate aquifers. In a seasonal production-injection cycle, water is circulated through a system comprising the porous aquifer, a production well, a heat exchanger and an injection well. This process involves large temperature and pressure differences, which shift chemical equilibria and introduce or amplify mechanical processes. Rock-fluid interaction such as dissolution and precipitation or migration and deposition of fine particles will affect the hydraulic properties of the porous medium and may lead to irreversible formation damage. In consequence, these processes determine the long-term performance of the ATES system and need to be predicted to ensure the reliability of the system. However, high temperature and pressure gradients and dynamic feedback cycles pose challenges on predicting the influence of the relevant processes. Within this study, a reservoir model comprising a coupled hydraulic-thermal-chemical simulation was developed based on an ATES demonstration project located in the city of Berlin, Germany. The structural model was created with Petrel, based on data available from seismic cross-sections and wellbores. The reservoir simulation was realized by combining the capabilities of multiple simulation tools. For the reactive transport model, COMSOL Multiphysics (hydraulic-thermal) and PHREEQC (chemical) were combined using the novel interface COMSOL_PHREEQC, developed by Wissmeier & Barry (2011). It provides a MATLAB-based coupling interface between both programs. Compared to using COMSOL's built-in reactive transport simulator, PHREEQC additionally calculates adsorption and reaction kinetics and allows the selection of different activity coefficient models in the database. The presented simulation tool will be able to predict the most important aspects of hydraulic, thermal and chemical transport processes relevant to

  7. Potential formation of bromophenols in Barcelona's tap water due to daily salt mine discharges and occasional phenol spills

    SciTech Connect

    Ventura, F.; Rivera, J.

    1986-02-01

    The presence of phenol and chlorinated phenols in drinking water has been shown to affect both taste and odor and to cause negative effects on health. The priority pollutants list issued by E.P.A. includes eleven of these compounds as suspected carcinogens. Little attention has been focussed on the presence of bromophenols. The presence of volatile brominated organic compounds has been demonstrated when bromide is present, due to chlorination. Similarly, brominated phenols might be formed during chlorination in the water works. More than 3 million inhabitants in the area of Barcelona drink water taken from Llobregat river. Quality of this raw water is strongly influenced by high contents of bromide coming from salt mines located in the upper course of the river. Phenol and phenolic compounds are usually found in raw water in the ppb range but occasional spills may increase the phenol content up to parts per million. This study shows the possibility of formation of bromophenols during normal chlorination conditions at Barcelona's water works plant.

  8. Localized sub-glacial deep karst formation due to water infiltration into glacier crevasses: A case study from Asiago, Italy

    NASA Astrophysics Data System (ADS)

    Tisato, Nicola; Frehner, Marcel; Busellato, Leonardo; Grasselli, Giovanni

    2015-04-01

    In karstic plateaus, deep karst phenomena (e.g. abysses) are the preferential pathways for surface water to penetrate the Earth's crust. After percolation along diaclases and meanders, the infiltrated water often springs at the foot of the karstic plateau, potentially representing a valuable water resource. Thus, it is crucial to understand the formation and distribution of deep karst phenomena, for instance to predict karstic groundwater flow paths or to preserve water resources from pollution. The role of glaciers in enhancing the formation of deep karst is not yet clear. On the one hand, chilly water retains more CO2 which increases its acidity and efficiency in corroding carbonates. On the other hand, glaciers obliterate the soil and vegetation covering the developing karst decreasing the quantity of humic acids dissolved in the surface water. Nevertheless, ice-caps may play a key role in controlling how and where surface water can access the developing karstic system. Due to the presence of a glacier, some sub-glacial areas may not be reached by surface water, which prevents karstification, while other areas may be connected to intra- or sub-glacial flow paths possibly leading to localized kartification in these areas. Here we investigate the relationship between sub-glacial topography and the development of preferred intra-glacier flow paths and how this relationship leads to localized sub-glacial karstification. As a case study site, we use the karstic plateau of Asiago in Northern Italy. The Asiago plateau (https://goo.gl/maps/bLezx) is mainly composed of Permian to Cretaceous rocks. The northern and southern boundaries of the plateau are marked by two Alpine trusts, which uplifted the plateau during the Alpine orogeny to ~1500 m above the Po flood plain delimiting the plateau to the South. The Asiago plateau extends for ~600 km2 and contains ~2100 natural caves, including many significantly deep caves such as the deepest cave of Veneto: the 1011 m deep

  9. Insight to UV-induced formation of laser damage on LiB(3)O(5) optical surfaces during long-term sum-frequency generation.

    PubMed

    Möller, S; Andresen, A; Merschjann, C; Zimmermann, B; Prinz, M; Imlau, M

    2007-06-11

    Microscopic investigations of UV-induced formation of laser damage on LiB(3)O(5) optical surfaces during long-term sum-frequency generation (SFG) uncovers a significant growth of a SiO(2)-amorphous layer spatially limited to the illuminated area. The layer gives rise to a catastrophic break-down of the LiB(3)O(5)-output surface upon long-term laser operation even at intensities far below the laser-induced damage threshold. The interaction of UV laser light, LiB(3)O(5) surface and foreign atoms in the ambient atmosphere is discussed in the frame of a two-step process for surface-damage formation.

  10. Oxidative damage-related genes AKR1C3 and OGG1 modulate risks for lung cancer due to exposure to PAH-rich coal combustion emissions.

    PubMed

    Lan, Qing; Mumford, Judy L; Shen, Min; Demarini, David M; Bonner, Matthew R; He, Xingzhou; Yeager, Meredith; Welch, Robert; Chanock, Stephen; Tian, Linwei; Chapman, Robert S; Zheng, Tongzhang; Keohavong, Phouthone; Caporaso, Neil; Rothman, Nathaniel

    2004-11-01

    Lung cancer rates among men and particularly among women, almost all of whom are non-smokers, in Xuan Wei County, China are among the highest in China and have been causally associated with exposure to indoor smoky coal emissions that contain very high levels of polycyclic aromatic hydrocarbons (PAHs). As such, this population provides a unique opportunity to study the pathogenesis of PAH-induced lung cancer that is not substantially influenced by the large number of other carcinogenic constituents of tobacco smoke. Aldo-keto reductases (AKRs) activate PAH dihydrodiols to yield their corresponding reactive and redox-active o-quinones, which can then generate reactive oxygen species that cause oxidative DNA damage. We therefore examined the association between single nucleotide polymorphisms (SNPs) in four genes (AKR1C3-Gln5His, NQO1-Pro187Ser, MnSOD-Val16Ala and OGG1-Ser326Cys) that play a role in the generation, prevention or repair of oxidative damage and lung cancer risk in a population-based, case-control study of 119 cases and 113 controls in Xuan Wei, China. The AKR1C3-Gln/Gln genotype was associated with a 1.84-fold [95% confidence interval (CI) = 0.98-3.45] increased risk and the combined OGG1-Cys/Cys and Ser/Cys genotypes were associated with a 1.93-fold (95% CI = 1.12-3.34) increased risk of lung cancer. Subgroup analysis revealed that the effects were particularly elevated among women who had relatively high cumulative exposure to smoky coal. SNPs in MnSOD and NQO1 were not associated with lung cancer risk. These results suggest that SNPs in the oxidative stress related-genes AKR1C3 and OGG1 may play a role in the pathogenesis of lung cancer in this population, particularly among heavily exposed women. However, due to the small sample size, additional studies are needed to evaluate these associations within Xuan Wei and other populations with substantial exposure to PAHs.

  11. Enhanced formation of secondary air pollutants and aggravation of urban smog due to crop residue burning emissions in North India

    NASA Astrophysics Data System (ADS)

    Sarkar, Chinmoy; Kumar, Vinod; Sinha, Vinayak

    2013-04-01

    implications for the oxidizing capacity of the atmosphere increased from an average value of 14 /s (N.F.E.) to 40 /s (F.E.) just due to CO, NOx and the measured aromatics. The observed increase in ozone was 10ppbV higher after sunrise on the day after the fire plume was sampled and driven by the sudden NOx availability at a site that normally falls in a NOx limited ozone production regime. The strong pollutant enhancements in carcinogenic aromatic hydrocarbons that are also highly reactive and fuel ozone and secondary organic aerosol formation when accompanied by the high NOx and CO levels resulting from crop residue burning in N. India, clearly highlight the need to address the practice of crop residue burning which strongly alters the composition and chemistry of the atmosphere with adverse effects on both air quality and health. This study is the first from within India to combine fast in-situ PTR-MS VOC emission tracer measurements with online measurements of primary pollutants and MODIS satellite data. Further targeted studies employing a comprehensive measurement suite of both aerosol and gas species are needed to assess the full impact of crop residue burning on atmospheric chemistry and regional air quality. Acknowledgement: We thank the IISER Mohali Atmospheric Chemistry Facility for data and the Ministry of Human Resource Development (MHRD),India and IISER Mohali for funding the facility. Vinod Kumar acknowledges the DST INSPIRE Fellowship programme. Chinmoy Sarkar thanks the Max Planck-DST India Partner Group on Tropospheric OH reactivity and VOCs for funding support.

  12. The DNA unwinding element binding protein DUE-B interacts with Cdc45 in preinitiation complex formation.

    PubMed

    Chowdhury, A; Liu, G; Kemp, M; Chen, X; Katrangi, N; Myers, S; Ghosh, M; Yao, J; Gao, Y; Bubulya, P; Leffak, M

    2010-03-01

    Template unwinding during DNA replication initiation requires the loading of the MCM helicase activator Cdc45 at replication origins. We show that Cdc45 interacts with the DNA unwinding element (DUE) binding protein DUE-B and that these proteins localize to the DUEs of active replication origins. DUE-B and Cdc45 are not bound at the inactive c-myc replicator in the absence of a functional DUE or at the recently identified ataxin 10 (ATX10) origin, which is silent before disease-related (ATTCT)(n) repeat length expansion of its DUE sequence, despite the presence of the origin recognition complex (ORC) and MCM proteins at these origins. Addition of a heterologous DUE to the ectopic c-myc origin, or expansion of the ATX10 DUE, leads to origin activation, DUE-B binding, and Cdc45 binding. DUE-B, Cdc45, and topoisomerase IIbeta binding protein 1 (TopBP1) form complexes in cell extracts and when expressed from baculovirus vectors. During replication in Xenopus egg extracts, DUE-B and Cdc45 bind to chromatin with similar kinetics, and DUE-B immunodepletion blocks replication and the loading of Cdc45 and a fraction of TopBP1. The coordinated binding of DUE-B and Cdc45 to origins and the physical interactions of DUE-B, Cdc45, and TopBP1 suggest that complexes of these proteins are necessary for replication initiation.

  13. Listeriolysin O Membrane Damaging Activity Involves Arc Formation and Lineaction -- Implication for Listeria monocytogenes Escape from Phagocytic Vacuole

    PubMed Central

    Ruan, Yi; Rezelj, Saša; Bedina Zavec, Apolonija; Anderluh, Gregor; Scheuring, Simon

    2016-01-01

    Listeriolysin-O (LLO) plays a crucial role during infection by Listeria monocytogenes. It enables escape of bacteria from phagocytic vacuole, which is the basis for its spread to other cells and tissues. It is not clear how LLO acts at phagosomal membranes to allow bacterial escape. The mechanism of action of LLO remains poorly understood, probably due to unavailability of suitable experimental tools that could monitor LLO membrane disruptive activity in real time. Here, we used high-speed atomic force microscopy (HS-AFM) featuring high spatio-temporal resolution on model membranes and optical microscopy on giant unilamellar vesicles (GUVs) to investigate LLO activity. We analyze the assembly kinetics of toxin oligomers, the prepore-to-pore transition dynamics and the membrane disruption in real time. We reveal that LLO toxin efficiency and mode of action as a membrane-disrupting agent varies strongly depending on the membrane cholesterol concentration and the environmental pH. We discovered that LLO is able to form arc pores as well as damage lipid membranes as a lineactant, and this leads to large-scale membrane defects. These results altogether provide a mechanistic basis of how large-scale membrane disruption leads to release of Listeria from the phagocytic vacuole in the cellular context. PMID:27104344

  14. Damage evolution and waveguide formation in SrTiO3 crystal irradiated by tens of MeV Si ions

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Huang, Q.; Qiao, M.; Wang, T. J.; Song, H. L.; Liu, P.; Wang, X. L.

    2017-09-01

    In this work, lattice damage behavior and optical waveguide formation in SrTiO3 crystal induced by swift ion irradiation have been studied. SrTiO3 crystal with (1 0 0) surface normal zone axis direction has been irradiated by 20 MeV Si3+ ions with a fluence of 1 × 1015 cm-2 at 300 K. Subsequently, structural damage induced by nuclear or electronic energy loss processes along ion penetration path has been analyzed by complementary characterization techniques, and the results indicate that the produced lattice damage in this case should be attributed to the nuclear energy loss. Utilizing the change of refractive index in lattice damage region, waveguide structure has been successfully prepared and the related optical properties have been studied through various coupling techniques. The iWKB (inverse Wentzel-Kramers-Brillouin)-reconstructed refractive-index profile of irradiation region appears reasonable correspondence (symmetrical inversion) with SRIM-simulated dpa profile, which also proves that lattice damage and waveguide formation in SrTiO3 should be ascribed to the nuclear energy loss during tens of MeV Si-ion irradiation process.

  15. Thermally enhanced formation of photon-induced damage on GaN films in Cl2 plasma

    NASA Astrophysics Data System (ADS)

    Liu, Zecheng; Asano, Atsuki; Imamura, Masato; Ishikawa, Kenji; Takeda, Keigo; Kondo, Hiroki; Oda, Osamu; Sekine, Makoto; Hori, Masaru

    2017-09-01

    Deep ultraviolet (UV) photons emitted from Cl2 plasmas become a critical cause of degradation in both photoluminescence (PL) properties and surface stoichiometry as a result of plasma-induced damage on GaN films in Cl2 plasma etching at high temperatures. The damages were formed thermally by photon-irradiations of plasma UV emissions with wavelengths of ˜258-306 nm from Cl2 plasma at temperatures greater than 500 °C. The damage were observed with a depth of approximately 3.2 nm. The PL property degraded by the UV emission-induced damage at an early period of plasma etching and reached a constant value.

  16. A Role for the Host DNA Damage Response in Hepatitis B Virus cccDNA Formation-and Beyond?

    PubMed

    Schreiner, Sabrina; Nassal, Michael

    2017-05-22

    Chronic hepatitis B virus (HBV) infection puts more than 250 million people at a greatly increased risk to develop end-stage liver disease. Like all hepadnaviruses, HBV replicates via protein-primed reverse transcription of a pregenomic (pg) RNA, yielding an unusually structured, viral polymerase-linked relaxed-circular (RC) DNA as genome in infectious particles. Upon infection, RC-DNA is converted into nuclear covalently closed circular (ccc) DNA. Associating with cellular proteins into an episomal minichromosome, cccDNA acts as template for new viral RNAs, ensuring formation of progeny virions. Hence, cccDNA represents the viral persistence reservoir that is not directly targeted by current anti-HBV therapeutics. Eliminating cccDNA will thus be at the heart of a cure for chronic hepatitis B. The low production of HBV cccDNA in most experimental models and the associated problems in reliable cccDNA quantitation have long hampered a deeper understanding of cccDNA molecular biology. Recent advancements including cccDNA-dependent cell culture systems have begun to identify select host DNA repair enzymes that HBV usurps for RC-DNA to cccDNA conversion. While this list is bound to grow, it may represent just one facet of a broader interaction with the cellular DNA damage response (DDR), a network of pathways that sense and repair aberrant DNA structures and in the process profoundly affect the cell cycle, up to inducing cell death if repair fails. Given the divergent interactions between other viruses and the DDR it will be intriguing to see how HBV copes with this multipronged host system.

  17. Mechanisms of freezing damage.

    PubMed

    Pegg, D E

    1987-01-01

    Freezing of aqueous systems involves numerous simultaneous changes but this review concentrates on direct effects of the formation of ice and the consequent concentration of solutes in the remaining liquid phase. It is generally believed that cell injury at low cooling rates is principally due to the concentration of both intracellular and extracellular electrolytes and that cryoprotectants act by reducing this build-up. New experimental data are presented to support this explanation; we find that the extent of damage to human red blood cells during freezing in solutions of sodium chloride/glycerol/water can be quantitatively accounted for by the increase in solute concentration. However, we also show that a given degree of damage occurs at lower concentrations of solute in the presence of higher concentrations of glycerol; it appears that glycerol contributes an element of damage itself. Recently published studies from Mazur's laboratory have suggested that the dominant damaging factor at low cooling rates is actually the reduction of the quantity of unfrozen water rather than the corresponding increase in salt concentration that accompanies freezing. These data are re-evaluated, and it is argued that the experimental results could equally well be explained by a susceptibility of cells to shrinkage and re-expansion as the concentration of external impermeant solutes first increases during freezing and then decreases during thawing. It is concluded that external ice probably has no directly damaging effect upon dilute suspensions of cells. However, it is also argued that ice is directly damaging whenever it forms intracellularly, and also when it forms extracellularly in densely packed cell suspensions. In the latter case the damage is probably due to recrystallization of the ice masses during thawing. Extracellular ice also has a directly damaging effect when tissues and organs are frozen. The difficulties of designing experimental methods that will yield

  18. Formation of ghost images due to metal objects on the surface of the patient's face: A pictorial essay

    PubMed Central

    Ramos, Bárbara Couto; da Silva Izar, Bruna Raquel; Pereira, Jéssica Lourdes Costa; Souza, Priscilla Sena; Valerio, Claudia Scigliano; Tuji, Fabrício Mesquita

    2016-01-01

    Panoramic radiographs are a relatively simple technique that is commonly used in all dental specialties. In panoramic radiographs, in addition to the formation of real images of metal objects, ghost images may also form, and these ghost images can hinder an accurate diagnosis and interfere with the accuracy of radiology reports. Dentists must understand the formation of these images in order to avoid making incorrect radiographic diagnoses. Therefore, the present study sought to present a study of the formation of panoramic radiograph ghost images caused by metal objects in the head and neck region of a dry skull, as well as to report a clinical case n order to warn dentists about ghost images and to raise awareness thereof. An understanding of the principles of the formation of ghost images in panoramic radiographs helps prevent incorrect diagnoses. PMID:27051642

  19. Formation of ghost images due to metal objects on the surface of the patient's face: A pictorial essay.

    PubMed

    Ramos, Bárbara Couto; da Silva Izar, Bruna Raquel; Pereira, Jéssica Lourdes Costa; Souza, Priscilla Sena; Valerio, Claudia Scigliano; Tuji, Fabrício Mesquita; Manzi, Flávio Ricardo

    2016-03-01

    Panoramic radiographs are a relatively simple technique that is commonly used in all dental specialties. In panoramic radiographs, in addition to the formation of real images of metal objects, ghost images may also form, and these ghost images can hinder an accurate diagnosis and interfere with the accuracy of radiology reports. Dentists must understand the formation of these images in order to avoid making incorrect radiographic diagnoses. Therefore, the present study sought to present a study of the formation of panoramic radiograph ghost images caused by metal objects in the head and neck region of a dry skull, as well as to report a clinical case n order to warn dentists about ghost images and to raise awareness thereof. An understanding of the principles of the formation of ghost images in panoramic radiographs helps prevent incorrect diagnoses.

  20. From art to science: the functional damage due to thumb osteoarthritis finely described by Velazquez 300 years before its clinical description.

    PubMed

    Villafañe, J H; Cantero-Tellez, R; Negrini, S; Berjano, P

    2017-09-21

    Velazquez showed to know the entity of thumb osteoarthritis by finely describing it in one of his paintings. The concepts of anatomical damage, loss of strenght, and functional impairment are transmitted to the observer.

  1. Experimental study of 351-nm and 527-nm laser-initiated surface damage on fused silica surfaces due to typical contaminants

    SciTech Connect

    Honig, J; Norton, M A; Hollingsworth, W G; Donohue, E E; Johnson, M A

    2004-11-08

    Optics damage under high-intensity illumination may be the direct result of laser light interaction with a contaminant on the surface. Contaminants of interest are small particles of the materials of construction of large laser systems and include aluminum, various absorbing glasses, and fused silica. In addition, once a damage site occurs and begins to grow, the ejecta from the growing damage site create contamination on nearby optic surfaces and may initiate damage on these surfaces via a process we call ''fratricide.'' We report on a number of experiments that we have performed on fused silica optics that were deliberately contaminated with materials of interest. The experiments were done using 527-nm light as well as 351-nm light. We have found that many of the contaminant particles are removed by the interaction with the laser and the likelihood of removal and/or damage is a function of both fluence and contaminant size. We have developed an empirical model for damage initiation in the presence of contaminants.

  2. Flexure with damage

    NASA Astrophysics Data System (ADS)

    Manaker, David M.; Turcotte, Donald L.; Kellogg, Louise H.

    2006-09-01

    Ductile behaviour in rocks is often associated with plasticity due to dislocation motion or diffusion under high pressures and temperatures. However, ductile behaviour can also occur in brittle materials. An example would be cataclastic flow associated with folding at shallow crustal levels. Engineers utilize damage mechanics to model the continuum deformation of brittle materials. In this paper we utilize a modified form of damage mechanics that includes a yield stress. Here, damage represents a reduction in frictional strength. We use this empirical approach to simulate bending of the lithosphere through the problem of plate flexure. We use numerical simulations to obtain quasi-static solutions to the Navier equations of elasticity. We use the program GeoFEST v. 4.5 (Geophysical Finite Element Simulation Tool), developed by NASA Jet Propulsion Laboratory, to generate solutions for each time step. When the von Mises stress exceeds the critical stress on an element we apply damage to reduce the shear modulus of the element. Damage is calculated at each time step by a power-law relationship of the ratio of the critical stress to the von Mises stress and the critical strain to the von Mises strain. This results in the relaxation of the material due to increasing damage. To test our method, we apply our damage rheology to a semi-infinite plate deforming under its own weight. Where the von Mises stress exceeds the critical stress, we simulate the formation of damage and observe the time-dependent relaxation of the stress and strain to near the yield strength. We simulate a wide range of behaviours from slow relaxation to instantaneous failure, over timescales that span six orders of magnitude. Using this method, stress relaxation produces perfectly plastic behaviour in cases where failure does not occur. For cases of failure, we observe a rapid increase in damage, analogous to the acceleration of microcrack formation and acoustic emissions prior to failure. Thus

  3. Numerical simulation of advection fog formation on multi-disperse aerosols due to combustion-related pollutants

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Liaw, G. S.

    1980-01-01

    The effects of multi-disperse distribution of the aerosol population are presented. Single component and multi-component aerosol species on the condensation/nucleation processes which affect the reduction in visibility are described. The aerosol population with a high particle concentration provided more favorable conditions for the formation of a denser fog than the aerosol population with a greater particle size distribution when the value of the mass concentration of the aerosols was kept constant. The results were used as numerical predictions of fog formation. Two dimensional observations in horizontal and vertical coordinates, together with time-dependent measurements were needed as initial values for the following physical parameters: (1)wind profiles; (2) temperature profiles; (3) humidity profiles; (4) mass concentration of aerosol particles; (5) particle size distribution of aerosols; and (6) chemical composition of aerosols. Formation and dissipation of advection fog, thus, can be forecasted numerically by introducing initial values obtained from the observations.

  4. The effects of environmental enrichment and beak-trimming during the rearing period on subsequent feather damage due to feather-pecking in laying hens.

    PubMed

    Hartcher, K M; Tran, K T N; Wilkinson, S J; Hemsworth, P H; Thomson, P C; Cronin, G M

    2015-05-01

    This experiment investigated effects of environmental enrichment and beak-trimming during the rearing period on behavior in rearing and plumage damage later in life. Treatments were applied in a 2 × 2 factorial arrangement. Half of the birds were beak-trimmed at 1 d of age using an infra-red laser. A follow-up light-trim was performed at 11 wk of age with a hot blade. Environmental enrichment consisted of pecking strings, whole oats in the litter, and greater litter depth. Sixteen pens of 50 ISA Brown laying hens were used. Four pullets were selected from each pen as focal birds and observed in their home pens between 3 and 14 wk of age. Plumage damage was scored at the end of the experiment in wk 43. Beak-trimmed birds performed less ground-pecking (P = 0.003), less severe feather-pecking (P = 0.021) and more gentle feather-pecking (P = 0.018) than their non-trimmed counterparts during the rearing period. These birds also exhibited less feather damage in wk 43 (P < 0.001). The results indicate that gentle feather-pecking during rearing is not related to plumage damage when older. Additionally, higher rates of ground-pecking and severe feather-pecking during rearing may be predictive of plumage damage later in life. There was no effect of enrichment on plumage damage. It was concluded that while there was no effect on enrichment, beak-trimming appeared to be effective in reducing plumage damage in wk 43.

  5. Effect of 800 keV argon ions pre-damage on the helium blister formation of tungsten exposed to 60 keV helium ions

    NASA Astrophysics Data System (ADS)

    Chen, Zhe; Han, Wenjia; Yu, Jiangang; Zhu, Kaigui

    2016-04-01

    This study aims to investigate the effect of Ar8+ ions pre-damage on the following He2+ irradiation behavior of polycrystalline tungsten. We compared the irradiation resistance performance against 60 keV He2+ ions of undamaged tungsten samples with that of pre-damaged samples which were preliminarily exposed to 800 keV Ar8+ ions at a fluence of 4 × 1019 ions m-2. The experimental results indicate that the helium blistering of tungsten could be effectively relieved by the Ar8+ ions pre-damage, while the retention of helium around low energy desorption sites in the pre-damaged tungsten was larger than that of the undamaged samples. A strong orientation dependence of blistering had been observed, with the blister occurred preferentially on the surface of grains with normal direction close to <111>. The Ar8+ ions irradiation-induced damage altered the morphology of helium bubbles in tungsten exposed to the following He2+ irradiation significantly. The intensity of helium release peaks at relatively low temperatures (<600 K) was enhanced due to Ar8+ ions pre-damage.

  6. Formation of higher-order nuclear Rad51 structures is functionally linked to p21 expression and protection from DNA damage-induced apoptosis.

    PubMed

    Raderschall, Elke; Bazarov, Alex; Cao, Jiangping; Lurz, Rudi; Smith, Avril; Mann, Wolfgang; Ropers, Hans-Hilger; Sedivy, John M; Golub, Efim I; Fritz, Eberhard; Haaf, Thomas

    2002-01-01

    After exposure of mammalian cells to DNA damage, the endogenous Rad51 recombination protein is concentrated in multiple discrete foci, which are thought to represent nuclear domains for recombinational DNA repair. Overexpressed Rad51 protein forms foci and higher-order nuclear structures, even in the absence of DNA damage, in cells that do not undergo DNA replication synthesis. This correlates with increased expression of the cyclin-dependent kinase (Cdk) inhibitor p21. Following DNA damage, constitutively Rad51-overexpressing cells show reduced numbers of DNA breaks and chromatid-type chromosome aberrations and a greater resistance to apoptosis. In contrast, Rad51 antisense inhibition reduces p21 protein levels and sensitizes cells to etoposide treatment. Downregulation of p21 inhibits Rad51 foci formation in both normal and Rad51-overexpressing cells. Collectively, our results show that Rad51 expression, Rad51 foci formation and p21 expression are interrelated, suggesting a functional link between mammalian Rad51 protein and p21-mediated cell cycle regulation. This mechanism may contribute to a highly effective recombinational DNA repair in cell cycle-arrested cells and protection against DNA damage-induced apoptosis.

  7. Effects of the feeding of wild Yeso sika deer (Cervus nippon yesoensis) on the prevention of damage due to bark stripping and the use of feeding sites.

    PubMed

    Masuko, Takayoshi; Souma, Kousaku; Kudo, Hirofumi; Takasaki, Yukari; Fukui, Emi; Kitazawa, Reiko; Nishida, Rikihiro; Niida, Toshimitsu; Suzuki, Teiji; Nibe, Akio

    2011-08-01

    Feeding sites for wild Yeso sika deer around Lake Akan, Japan, were established. Effects on the number of deer using the feeding sites, the prevention of bark stripping damage, the amount of feeding, and eating time in a 5-year period (1999-2003) were evaluated. The number of deer using feeding sites increased with years during the feeding period. The damaged tree ratio after the initiation of feeding markedly decreased compared with 16.5% before the initiation of feeding. After the start of feeding, there were no trees with damage the entire circumference. According to tree species, the number of damaged trees of Ulmus laciniata Mayr as a percentage of all investigated trees was high (5.2%). The total amount of beet pulp feeding increased with the feeding year, showing 4.5-fold increase. At feeding sites in deer culling, eating behavior was observed during the night. The preventive effects on bark stripping damage continued during the 5-year feeding period. However, with the course of feeding years, the number of deer using feeding sites and the level of feeding increased. 2011 The Authors. Animal Science Journal © 2011 Japanese Society of Animal Science.

  8. Protective effect of early placement of nasogastric tube with solid dilator on tissue damage and stricture formation after caustic esophageal burns in rabbits.

    PubMed

    Defagó, Victor; Moyano, Jimena; Bernhardt, Celina; Sambuelli, Gabriela; Cuestas, Eduardo

    2015-08-01

    The ingestion of caustic substances remains an important public health issue worldwide. Children represent 80% of the ingestion injury population globally. Accidental alkaline material accounts for most caustic ingestions. There is no conclusive evidence of tissue damage and stricture protection of a nasogastric-tube with a solid dilator in the literature, therefore it was hypothesized that early intraesophageal tube placement does not cause additional histopathologic damage and prevents strictures. An exploratory study on experimental caustic esophageal burns in a rabbit model was designed. In the treated group a silicone tube was placed immediately after causing the burns, while the untreated group followed the natural course of the burn. On the twenty-secondday, an esophagectomy was performed on all animals for microscopic (Histopathologic Damage Score and Stenosis Index) and macroscopic analysis. Forty animals were randomly divided into two groups. The Histopathologic Damage Score was 3.7±1.1 in the treated group versus 3.9±1.2 in the untreated group (p=.9690). The Stenosis Index was 0.6±0.1 in treated rabbits versus 2.3±0.2 in untreated (p<.0001). The early placement of an intraesophageal tube with solid dilator prevents stenosis formation and does not produce greater tissue damage. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Formation of high-stress phase and extrusion of polyethylene due to nanoconfinements during Ziegler-Natta polymerization inside nanochannels.

    PubMed

    Nair, Sujith; Naredi, Prabhat; Kim, Seong H

    2005-06-30

    Polyethylene nanofibers were synthesized by heterogeneous Ziegler-Natta polymerization inside nanochannels of robust anodized aluminum oxide (AAO) membranes. The polymerization catalysts were chemisorbed at the inner wall of the nanochannels and monomers were provided through diffusion from the outside. Polyethylene is produced inside the nanochannels in the 10-20 mum region from the channel entrance. Polyethylene fibers were extruded from the nanochannels up to 3-5 mum during the polymerization. X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared analyses indicated formation of a highly stressed crystalline structure although the polymerization was carried out without any external pressure or mechanical work. The highly stressed phase formation inside nanochannels and some degree of polyethylene nanofiber extrusion from nanochannels were attributed to catalytic production of excess amounts of polyethylene inside nanoconfined templates.

  10. Kinetics of the formation of ozone and nitrogen oxides due to a pulsed microwave discharge in air

    NASA Astrophysics Data System (ADS)

    Larin, V. F.; Rumiantsev, S. A.

    1989-03-01

    The paper presents results of a numerical simulation of the kinetics of plasma-chemical processes induced by a single microwave pulse in the stratosphere. It is shown that the gas temperature is one of the main factors influencing the concentration ratio of ozone and nitrogen oxides formed under the effect of a microwave pulse. Long pulses, producing considerable gas heating, favor the formation of nitrogen oxides.

  11. Rupture of pluronic micelles by di-methylated β-cyclodextrin is not due to polypseudorotaxane formation.

    PubMed

    Valero, Margarita; Grillo, Isabelle; Dreiss, Cécile A

    2012-02-02

    Spectroscopic measurements (uv/vis absorbance and fluorescence) and time-resolved small-angle neutron scattering experiments (TR-SANS) were used to follow the breakdown of Pluronic micelles by heptakis(2,6-di-O-methyl)-β-cyclodextrin (DIMEB) over time in order to elucidate the mechanism of micellar rupture, generally attributed to polypseudotorotaxane (PR) formation between the cyclodextrin and the central hydrophobic PPO block. The spectroscopic measurements with two different probes (methyl orange and nile red) suggest that very rapid changes (on the order of seconds) take place when mixing DIMEB with F127 Pluronic and that no displacement of the probe from the cyclodextrin cavity occurs, which is in disagreement with PR formation. TR-SANS measurements demonstrate for the first time that the micelles are broken down in less than 100 ms, which categorically rules out PR formation as the mechanism of rupture. In addition, the same mechanism is demonstrated with other Pluronics, P85 and P123. In the latter case, after micellar rupture, lamellar structures are seen to form over a longer period of time, thus suggesting that after the instantaneous micellar disruption, further, longer-scale rearrangements are not excluded.

  12. Spatial Dependence of DNA Damage in Bacteria due to Low-Temperature Plasma Application as Assessed at the Single Cell Level

    NASA Astrophysics Data System (ADS)

    Privat-Maldonado, Angela; O'Connell, Deborah; Welch, Emma; Vann, Roddy; van der Woude, Marjan W.

    2016-10-01

    Low temperature plasmas (LTPs) generate a cocktail of reactive nitrogen and oxygen species (RNOS) with bactericidal activity. The RNOS however are spatially unevenly distributed in the plasma. Here we test the hypothesis that this distribution will affect the mechanisms underpinning plasma bactericidal activity focussing on the level of DNA damage in situ. For the first time, a quantitative, single cell approach was applied to assess the level of DNA damage in bacteria as a function of the radial distance from the centre of the plasma jet. Salmonella enterica on a solid, dry surface was treated with two types of LTP: an atmospheric-pressure dielectric barrier discharge plasma jet (charged and neutral species) and a radio-frequency atmospheric-pressure plasma jet (neutral species). In both cases, there was an inverse correlation between the degree of DNA damage and the radial distance from the centre of the plasma, with the highest DNA damage occurring directly under the plasma. This trend was also observed with Staphylococcus aureus. LTP-generated UV radiation was eliminated as a contributing factor. Thus valuable mechanistic information can be obtained from assays on biological material, which can inform the development of LTP as a complementary or alternative therapy for (topical) bacterial infections.

  13. OXIDATIVE DAMAGE-RELATED GENES AKR1C3 AND OGG1 MODULATE RISKS FOR LUNG CANCER DUE TO EXPOSURE TO PAH-RICH COAL COMBUSTION EMISSIONS

    EPA Science Inventory

    We studied polymorphisms in genes that generate, prevent, or repair oxidative damage and lung cancer risk among 118 cases and 113 controls in Xuan Wei China, where extremely high lung cancer rates are caused by indoor exposure to smoky coal. SOD2-Vak16Ala and NQO1-Pro 187Ser were...

  14. OXIDATIVE DAMAGE-RELATED GENES AKR1C3 AND OGG1 MODULATE RISKS FOR LUNG CANCER DUE TO EXPOSURE TO PAH-RICH COAL COMBUSTION EMISSIONS

    EPA Science Inventory

    We studied polymorphisms in genes that generate, prevent, or repair oxidative damage and lung cancer risk among 118 cases and 113 controls in Xuan Wei China, where extremely high lung cancer rates are caused by indoor exposure to smoky coal. SOD2-Vak16Ala and NQO1-Pro 187Ser were...

  15. Spatial Dependence of DNA Damage in Bacteria due to Low-Temperature Plasma Application as Assessed at the Single Cell Level

    PubMed Central

    Privat-Maldonado, Angela; O’Connell, Deborah; Welch, Emma; Vann, Roddy; van der Woude, Marjan W.

    2016-01-01

    Low temperature plasmas (LTPs) generate a cocktail of reactive nitrogen and oxygen species (RNOS) with bactericidal activity. The RNOS however are spatially unevenly distributed in the plasma. Here we test the hypothesis that this distribution will affect the mechanisms underpinning plasma bactericidal activity focussing on the level of DNA damage in situ. For the first time, a quantitative, single cell approach was applied to assess the level of DNA damage in bacteria as a function of the radial distance from the centre of the plasma jet. Salmonella enterica on a solid, dry surface was treated with two types of LTP: an atmospheric-pressure dielectric barrier discharge plasma jet (charged and neutral species) and a radio-frequency atmospheric-pressure plasma jet (neutral species). In both cases, there was an inverse correlation between the degree of DNA damage and the radial distance from the centre of the plasma, with the highest DNA damage occurring directly under the plasma. This trend was also observed with Staphylococcus aureus. LTP-generated UV radiation was eliminated as a contributing factor. Thus valuable mechanistic information can be obtained from assays on biological material, which can inform the development of LTP as a complementary or alternative therapy for (topical) bacterial infections. PMID:27759098

  16. Positive regulation of meiotic DNA double-strand break formation by activation of the DNA damage checkpoint kinase Mec1(ATR).

    PubMed

    Gray, Stephen; Allison, Rachal M; Garcia, Valerie; Goldman, Alastair S H; Neale, Matthew J

    2013-07-31

    During meiosis, formation and repair of programmed DNA double-strand breaks (DSBs) create genetic exchange between homologous chromosomes-a process that is critical for reductional meiotic chromosome segregation and the production of genetically diverse sexually reproducing populations. Meiotic DSB formation is a complex process, requiring numerous proteins, of which Spo11 is the evolutionarily conserved catalytic subunit. Precisely how Spo11 and its accessory proteins function or are regulated is unclear. Here, we use Saccharomyces cerevisiae to reveal that meiotic DSB formation is modulated by the Mec1(ATR) branch of the DNA damage signalling cascade, promoting DSB formation when Spo11-mediated catalysis is compromised. Activation of the positive feedback pathway correlates with the formation of single-stranded DNA (ssDNA) recombination intermediates and activation of the downstream kinase, Mek1. We show that the requirement for checkpoint activation can be rescued by prolonging meiotic prophase by deleting the NDT80 transcription factor, and that even transient prophase arrest caused by Ndt80 depletion is sufficient to restore meiotic spore viability in checkpoint mutants. Our observations are unexpected given recent reports that the complementary kinase pathway Tel1(ATM) acts to inhibit DSB formation. We propose that such antagonistic regulation of DSB formation by Mec1 and Tel1 creates a regulatory mechanism, where the absolute frequency of DSBs is maintained at a level optimal for genetic exchange and efficient chromosome segregation.

  17. Nanograin formation and reaction-induced fracturing due to decarbonation: Implications for the microstructures of fault mirrors

    NASA Astrophysics Data System (ADS)

    Pluymakers, A.; Røyne, A.

    2017-10-01

    Principal slip zones often contain highly reflective surfaces referred to as fault mirrors, shown to consist of a nanogranular coating. There is currently no consensus on how the nanograins form, or why they survive weathering on a geological time-scale. To simplify the complex system of a natural fault zone, where slip and heat generation are inherently coupled, we investigated the effect of elevated temperatures on carbonate rock surfaces, as well as their resistance to water exposure. This allows us to isolate the role of the decarbonation process in the formation of nanograins. We used cleaved crystals of Iceland spar calcite, manually polished dolomite protolith, as well as natural dolomite fault mirror surfaces. The samples were heated to 200-800 °C in a ∼5 h heating cycle, followed by slow cooling (∼12 h) to room temperature. Subsequently, we imaged the samples using scanning electron microscopy and atomic force microscopy. Nanograin formation on all sample surfaces was pervasive at and above 600 °C. The Foiana fault mirror samples were initially coated with aligned naturally-formed nanograins, but display a non-directional nanogranular coating after heating. The nanograins that were formed by heating rapidly recrystallized to bladed hydroxides upon exposure to deionized water, whereas the nanograins on unheated fault mirror samples remained unchanged in water. This shows that the nanograins formed by heating alone are different from those formed in fault zones, and calls for a better characterization of nanograins and their formation mechanisms. Furthermore, we find a characteristic star-shaped crack pattern associated with reacted regions of the carbonate surfaces. The existence of this pattern implies that the mechanical stresses set up by the decarbonation reaction can be sufficiently large to drive fracturing in these systems. We propose that this mechanism may contribute to grain size reduction in fault zones.

  18. Vitamin U has a protective effect on valproic acid-induced renal damage due to its anti-oxidant, anti-inflammatory, and anti-fibrotic properties.

    PubMed

    Gezginci-Oktayoglu, Selda; Turkyilmaz, Ismet Burcu; Ercin, Merve; Yanardag, Refiye; Bolkent, Sehnaz

    2016-01-01

    The aim of present study was to investigate the effect of vitamin U (vit U, S-methylmethionine) on oxidative stress, inflammation, and fibrosis within the context of valproic acid (VPA)-induced renal damage. In this study, female Sprague Dawley rats were randomly divided into four groups: Group I consisted of intact animals, group II was given vit U (50 mg/kg/day, by gavage), group III was given VPA (500 mg/kg/day, intraperitonally), and group IV was given VPA + vit U. The animals were treated by vit U 1 h prior to treatment with VPA every day for 15 days. The following results were obtained in vit U + VPA-treated rats: (i) the protective effect of vit U on renal damage was shown by a significant decrease in histopathological changes and an increase in Na(+)/K(+)-ATPase activity; (ii) anti-oxidant property of vit U was demonstrated by a decrease in malondialdehyde levels and xanthine oxidase activity and an increase in glutathione levels, catalase and superoxide dismutase activities; (iii) anti-inflammatory property of vit U was demonstrated by a decrease in tumor necrosis factor-α, interleukin-1β, monocyte chemoattractant protein-1 levels, and adenosine deaminase activity; (iv) anti-fibrotic effect of vit U was shown by a decrease in transforming growth factor-β, collagen-1 levels, and arginase activity. Collectively, these data show that VPA is a promoter of inflammation, oxidative stress, and fibrosis which resulted in renal damage. Vit U can be proposed as a potential candidate for preventing renal damage which arose during the therapeutic usage of VPA.

  19. Choice of Cell Source in Cell-Based Therapies for Retinal Damage due to Age-Related Macular Degeneration: A Review.

    PubMed

    John, Sudhakar; Natarajan, Sundaram; Parikumar, Periyasamy; Shanmugam P, Mahesh; Senthilkumar, Rajappa; Green, David William; Abraham, Samuel J K

    2013-01-01

    Background. Age-related macular degeneration (AMD) is a complex disorder that affects primarily the macula involving the retinal pigment epithelium (RPE) but also to a certain extent the photoreceptor layer and the retinal neurons. Cell transplantation is a promising option for AMD and clinical trials are underway using different cell types. Methods. We hypothesize that instead of focusing on a particular cell source for concurrent regeneration of all the retinal layers and also to prevent exhaustive research on an array of cell sources for regeneration of each layer, the choice should depend on, precisely, which layer is damaged. Results. Thus, for a damage limited to the retinal pigment epithelial (RPE) layer, the choice we suggest would be RPE cells. When the damage extends to rods and cones, the choice would be bone marrow stem cells and when retinal neurons are involved, relatively immature stem cell populations with an inherent capacity to yield neuronal lineage such as hematopoietic stem cells, embryonic stem cells, or induced pluripotent stem cells can be tried. Conclusion. This short review will prove to be a valuable guideline for those working on cell therapy for AMD to plan their future directions of research and therapy for this condition.

  20. The coffee constituent chlorogenic acid induces cellular DNA damage and formation of topoisomerase I- and II-DNA complexes in cells.

    PubMed

    Burgos-Morón, Estefanía; Calderón-Montaño, José Manuel; Orta, Manuel Luis; Pastor, Nuria; Pérez-Guerrero, Concepción; Austin, Caroline; Mateos, Santiago; López-Lázaro, Miguel

    2012-08-01

    Chlorogenic acid (CGA) is a plant polyphenol with known antioxidant properties. Although some studies suggest that CGA has anticancer properties, others indicate that this dietary constituent may cause DNA damage and induce carcinogenic effects. Because CGA is widely consumed in the form of coffee, it is important to further evaluate the putative DNA-damaging activity of CGA. Here we have employed two standard techniques commonly used for DNA damage detection (the comet assay and the γ- H2AX focus assay) and observed that CGA (0.5-5 mM) induces DNA damage in normal and cancer cells. We report for the first time that CGA induces high levels of topoisomerase I- and topoisomerase II-DNA complexes in cells (TARDIS assay). Catalase pretreatment abolished the formation of these topoisomerase-DNA complexes and reduced the cytotoxic activity of CGA, therefore indicating that hydrogen peroxide plays an important role in these activities. Lung cancer cells (A549) were more sensitive than normal lung fibroblasts (MRC5) to the cytotoxic activity of CGA, supporting previous findings that CGA may induce selective killing of cancer cells. Taking into consideration our results and the pharmacokinetic profile of CGA, the possible cancer preventive, carcinogenic and therapeutic potential of this dietary agent are discussed.

  1. Alpha, beta-unsaturated lactones 2-furanone and 2-pyrone induce cellular DNA damage, formation of topoisomerase I- and II-DNA complexes and cancer cell death.

    PubMed

    Calderón-Montaño, José Manuel; Burgos-Morón, Estefanía; Orta, Manuel Luis; Pastor, Nuria; Austin, Caroline A; Mateos, Santiago; López-Lázaro, Miguel

    2013-09-12

    The alpha, beta-unsaturated lactones 2-furanone and 2-pyrone are part of the chemical structure of a variety of naturally occurring compounds (e.g., cardenolides, bufadienolides, acetogenins, coumarins, and food-flavoring furanones), some of which have shown anticancer activity and/or DNA damaging effects. Here we report that 2-furanone and 2-pyrone induce cellular DNA damage (assessed by the comet assay and the gamma-H2AX focus assay) and the formation of topoisomerase I- and topoisomerase II-DNA complexes in cells (visualized and quantified in situ by the TARDIS assay). Cells mutated in BRCA2 (deficient in homologous recombination repair) were significantly hypersensitive to the cytotoxic activity of 2-pyrone, therefore suggesting that BRCA2 plays an important role in the repair of DNA damage induced by this lactone. Both lactones were cytotoxic in A549 lung cancer cells at lower concentrations than in MRC5 non-malignant lung fibroblasts. The possible involvement of 2-furanone and 2-pyrone in the anticancer and DNA-damaging activities of compounds containing these lactones is discussed. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  2. Vortex Ring Formation Characteristics in Synthetic Jet due to Changes of Excitation Frequency in the ½-Ball Cavity Actuator

    NASA Astrophysics Data System (ADS)

    Kosasih, Engkos A.; Harinaldi; Trisno, Ramon

    2017-04-01

    A jet flow that contains vortex ring has a large energy compared to a regular jet. As one of the causes of the aerodynamic drag to the vehicle, the flow separation that occurs behind the bluff body must be controlled, so that aerodynamic drag can be significantly reduced. This study is a basic work on the development of turbulent flow separation control for aerodynamic purpose, especially in the design of the vehicle body. The main objective of this study is to analyze the performance of the synthetic jet (SJA) as one of flow control tool to reduce separation area. To get the maximum performance of the synthetic jet actuator, the research starts by characterizing the actuator. Characterization of ½ ball-shaped cavity is done with excitation frequency changes and orifice diameter of 3, 5 and 8 mm. The study was conducted using computational and experimental methods. The experimental data was obtained by testing synthetic jet actuator with providing sinusoidal signal to drive the membrane and at the orifice end a hotwire probe that is set and plugged into a CTA (Constant Temperature Anemometry) to obtain the speed velocity of the exhaust jet. Computational methods used a commercial CFD software (FLUENT 6.3) with a Reynolds Stress Model as a model of turbulence. Each of these calculations or measurements was conducted under the same conditions. The research result is displayed in frequency testing curve to get the maximum velocity of the jet stream. The results are further indicative of the synthetic jet actuator capability to generate vortex rings. In the experimental results, the determination of ring vortex formation taken from the calculation of the flow velocity, while the CFD simulations, the formation of vortex rings can be seen from the visualization of the flow contour. Vortex ring formed from this ½ -ball cavity, occurred at 3 mm and 5 mm orifice diameter, while the 8 mm orifice diameter cavity cannot form a ring vortex.

  3. Porous media deformation due to fluid flow: From hydrofracture formation to seismic liquefaction, a numerical and experimental study

    NASA Astrophysics Data System (ADS)

    Toussaint, R.; Turkaya, S.; Eriksen, F.; Clément, C.; Sanchez-Colina, G.; Maloy, K. J.; Flekkoy, E.; Aharonov, E.; Lengliné, O.; Daniel, G.; Altshuler, E.; Batista-Leyva, A.; Niebling, M.

    2016-12-01

    We present here the deformation of porous media in two different situations: 1. The formation of channels and fracture during pressurization of pore fluids, as happens during eruptions or injection of fluids and gas into soils and rocks. 2. The liquefaction of soils at different degrees of saturations during Earthquakes. The formation of channels during hydrofracture and pneumatic fractures is studied in laboratory experiments and in numerical models. The experiments are done on different types of porous media in Hele-Shaw cells, where fluid is injected at controlled overpressures, and various boundary conditions are used. Using fast cameras, we determine the strain and velocity fields from the images. We also record the characteristics of micro-seismic emissions during the process, and link this seismic record features and the direct image of the displacement responsible for the seismic sources in the medium. We also carry out numerical simulations, using coupled fluid/solid hydrid models that capture solid stress, pore pressure, solid and fluid elasticity - a full poro-elasto-plastic model using granular representation of the solid and a continuous one for the fluid.Next, Soil liquefaction is a significant natural hazard associated with earthquakes. Some of its devastating effects include tilting and sinking of buildings and bridges, and destruction of pipelines. Conventional geotechnical engineering assumes liquefaction occurs via elevated pore pressure. This assumption guides construction for seismically hazardous locations, yet evidence suggests that liquefaction strikes also under currently unpredicted conditions. We show, using theory, simulations and experiments, another mechanism for liquefaction in saturated soils, without high pore fluid pressure and without special soils, whereby liquefaction is controlled by buoyancy forces. This new mechanism enlarges the window of conditions under which liquefaction is predicted to occur, and may explain previously

  4. Osteogenesis imperfecta due to mutations in non-collagenous genes: lessons in the biology of bone formation.

    PubMed

    Marini, Joan C; Reich, Adi; Smith, Simone M

    2014-08-01

    Osteogenesis imperfecta or 'brittle bone disease' has mainly been considered a bone disorder caused by collagen mutations. Within the last decade, however, a surge of genetic discoveries has created a new paradigm for osteogenesis imperfecta as a collagen-related disorder, where most cases are due to autosomal dominant type I collagen defects, while rare, mostly recessive, forms are due to defects in genes whose protein products interact with collagen protein. This review is both timely and relevant in outlining the genesis, development, and future of this paradigm shift in the understanding of osteogenesis imperfecta. Bone-restricted interferon-induced transmembrane (IFITM)-like protein (BRIL) and pigment epithelium-derived factor (PEDF) defects cause types V and VI osteogenesis imperfecta via defective bone mineralization, while defects in cartilage-associated protein (CRTAP), prolyl 3-hydroxylase 1 (P3H1), and cyclophilin B (CYPB) cause types VII-IX osteogenesis imperfecta via defective collagen post-translational modification. Heat shock protein 47 (HSP47) and FK506-binding protein-65 (FKBP65) defects cause types X and XI osteogenesis imperfecta via aberrant collagen crosslinking, folding, and chaperoning, while defects in SP7 transcription factor, wingless-type MMTV integration site family member 1 (WNT1), trimeric intracellular cation channel type b (TRIC-B), and old astrocyte specifically induced substance (OASIS) disrupt osteoblast development. Finally, absence of the type I collagen C-propeptidase bone morphogenetic protein 1 (BMP1) causes type XII osteogenesis imperfecta due to altered collagen maturation/processing. Identification of these multiple causative defects has provided crucial information for accurate genetic counseling, inspired a recently proposed functional grouping of osteogenesis imperfecta types by shared mechanism to simplify current nosology, and has prodded investigations into common pathways in osteogenesis imperfecta. Such

  5. Formation of a unilateral form deprivation myopia (FDM) due to a congenital eyelid entropium with a consecutive corneal ulcer: an illustrated case report.

    PubMed

    Schellenbeck, M; Hartmann, Chr; Schwarz, E C

    2002-06-01

    Eye growth is regulated by a precise, sharp image of a distant object on the photoreceptor layer. A variety of laboratory investigations report that translucent occluders may induce axial eye elongation in animals. This axial growth is also called form deprivation myopia (FDM). In our pediatric ophthalmology clinic we observed the clinical correlate of FDM in a male infant with unilateral corneal ulcer due to a congenital tarsal malformation. Examination in the postnatal period under anesthesia revealed identical axial length in both eyes. Refraction of the affected eye could not be measured due to severe corneal ulcer. During an observation period of two years, the deep corneal opacification of the affected eye induced unilateral disproportionate axial elongation with formation of myopia. Formation of FDM may complicate treatment of amblyopia following unilateral media opacification. Periodic measurements of refraction should be performed to allow appropriate correction.

  6. Measurements of thermal electron heating and the formation of a non-Maxwellian energy distribution due to ion acoustic turbulence

    SciTech Connect

    Hargreaves, T.A.

    1982-01-01

    The interaction of intense microwaves with an inhomogeneous plasma is studied in the U.C. Davis Prometheus III Device. P-polarized microwaves (f = 1.2 GHz, P/sub 0/ less than or equal to 5 KW) are incident on an essentially collisionless plasma with a long scale length in an oversized waveguide. For modest powers, large amplitude ion acoustic turbulence is observed on the underdense plasma shelf due to a combination of the parametric decay and the electron drift instabilities. Suprathermal and thermal electrons are strongly heated in this region with the thermal heating due to scattering with the ion turbulence. Since the cross section for interaction decreases rapidly as the electron energy increases, the low energy electrons are preferentially heated. The electron distribution function is measured and agrees with theory; the power absorption is reduced by up to a factor of two compared to a Maxwellian distribution. After the microwaves have been measured to decay, the electron distribution function is seen to relax back to its initial Maxwellian form. This occurs, as theory predicts, roughly on the electron-electron collision time scale.

  7. On the possibility of solar dust ring formation due to increased dust-ion drag from coronal mass ejections

    NASA Astrophysics Data System (ADS)

    Misconi, N. Y.; Pettera, L. E.

    1995-07-01

    Model calculations of circumsolar dust are conducted taking into account the increased ion drag due to the interaction of F-coronal dust with CMEs inside 8 Rs. The choice of 8 Rs is not arbitrary, after considering the severe plasma environment inside this region. Dust particles are allowed to spiral inward towards the Sun via the Poynting-Robertson drag, and the characteristics of the CMEs are applied in order to numerically compute the increased ion drag on F-coronal dust. The results show that the spiraling time would roughly be cut in half for dust particles inside 8 Rs. Differences in the spiraling time due to the dependence of the magnitude of increased ion drag on dust particle size, creates separation in the heliocentric distance of the orbits of small (> 10 μm) vs. larger particles. This result could create conditions where a dust ring or rings may appear as a transient feature, which would explain former citing of such dust rings by observers and their absence by others.

  8. Large Crystal Toxin Formation in Chromosomally Engineered Bacillus thuringiensis subsp. aizawai Due to σE Accumulation

    PubMed Central

    Buasri, Wasin

    2012-01-01

    Seven distinct Bacillus thuringiensis subsp. aizawai integrants were constructed that carried the chitinase (chiBlA) gene from B. licheniformis under the control of the cry11Aa promoter and terminator with and without p19 and p20 genes. The toxicity of B. thuringiensis subsp. aizawai integrants against second-instar Spodoptera litura larvae was increased 1.8- to 4.6-fold compared to that of the wild-type strain (BTA1). Surprisingly, the enhanced toxicity in some strains of B. thuringiensis subsp. aizawai integrants (BtaP19CS, BtaP19CSter, and BtaCAT) correlated with an increase in toxin formation. To investigate the role of these genes in toxin production, the expression profiles of the toxin genes, cry1Aa and chiBlA, as well as their transcriptional regulators (sigK and sigE), were analyzed by quantitative real-time RT-PCR (qPCR) from BTA1, BtaP19CS, and BtaCAT. Expression levels of cry1Aa in these two integrants increased about 2- to 3-fold compared to those of BTA1. The expression of the transcription factor sigK also was prolonged in the integrants compared to that of the wild type; however, sigE expression was unchanged. Western blot analysis of σE and σK showed the prolonged accumulation of σE in the integrants compared to that of BTA1, resulting in the increased synthesis of pro-σK up to T17 after the onset of sporulation in both BtaP19CS and BtaCAT compared to that of T13 in BTA1. The results from qPCR indicate clearly that the cry1Aa promoter activity was influenced most strongly by σE, whereas cry11Aa depended mostly on σK. These results on large-crystal toxin formation with enhanced toxicity should provide useful information for the generation of strains with improved insecticidal activity. PMID:22267677

  9. Air exposure behavior of the semiterrestrial crab Neohelice granulata allows tolerance to severe hypoxia but not prevent oxidative damage due to hypoxia-reoxygenation cycle.

    PubMed

    de Lima, Tábata Martins; Geihs, Márcio Alberto; Nery, Luiz Eduardo Maia; Maciel, Fábio Everton

    2015-11-01

    The air exposure behavior of the semi-terrestrial crab Neohelice granulata during severe hypoxia was studied. This study also verified whether this behavior mitigates possible oxidative damage, namely lipoperoxidation, caused by hypoxia and reoxygenation cycles. The lethal time for 50% of the crabs subjected to severe hypoxia (0.5 mgO2 · L(-1)) with free access to air was compared to that of crabs subjected to severe hypoxia without access to air. Crabs were placed in aquaria divided into three zones: water (when the animal was fully submersed), land (when the animal was completely emerged) and intermediate (when the animal was in contact with both environments) zones. Then the crabs were held in this condition for 270 min, and the time spent in each zone was recorded. Lipid peroxidation (LPO) damage to the walking leg muscles was determined for the following four experimental conditions: a--normoxic water with free access to air; b--hypoxic water without access to air; c--hypoxic water followed by normoxic water without air access; and d--hypoxic water with free access to air. When exposed to hypoxic water, N. granulata spent significantly more time on land, 135.3 ± 17.7 min, whereas control animals (exposed to normoxic water) spent more time submerged, 187.4 ± 20.2 min. By this behavior, N. granulata was able to maintain a 100% survival rate when exposed to severe hypoxia. However, N. granulata must still return to water after periods of air exposure (~ 14 min), causing a sequence of hypoxia/reoxygenation events. Despite increasing the survival rate, hypoxia with air access does not decrease the lipid peroxidation damage caused by the hypoxia and reoxygenation cycle experienced by these crabs.

  10. Intrusion of Fukushima-derived radiocaesium into subsurface water due to formation of mode waters in the North Pacific.

    PubMed

    Kaeriyama, Hideki; Shimizu, Yugo; Setou, Takashi; Kumamoto, Yuichiro; Okazaki, Makoto; Ambe, Daisuke; Ono, Tsuneo

    2016-02-26

    The Fukushima Dai-ichi Nuclear Power Plant accident in March 2011 released radiocaesium ((137)Cs and (134)Cs) into the North Pacific Ocean. Meridional transects of the vertical distribution of radiocaesium in seawater were measured along 147 °E and 155 °E in October-November 2012, 19 months after the accident. These measurements revealed subsurface peaks in radiocaesium concentrations at locations corresponding to two mode waters, Subtropical Mode Water and Central Mode Water. Mode water is a layer of almost vertically homogeneous water found over a large geographical area. Here we show that repeated formation of mode water during the two winter seasons after the Fukushima accident and subsequent outcropping into surface water transported radiocaesium downward and southward to subtropical regions of the North Pacific. The total amount of Fukushima-derived (134)Cs within Subtropical Mode Water, decay-corrected to April 2011, was estimated to be 4.2 ± 1.1 PBq in October-November 2012. This amount of (134)Cs corresponds to 22-28% of the total amount of (134)Cs released to the Pacific Ocean.

  11. Intrusion of Fukushima-derived radiocaesium into subsurface water due to formation of mode waters in the North Pacific

    PubMed Central

    Kaeriyama, Hideki; Shimizu, Yugo; Setou, Takashi; Kumamoto, Yuichiro; Okazaki, Makoto; Ambe, Daisuke; Ono, Tsuneo

    2016-01-01

    The Fukushima Dai-ichi Nuclear Power Plant accident in March 2011 released radiocaesium (137Cs and 134Cs) into the North Pacific Ocean. Meridional transects of the vertical distribution of radiocaesium in seawater were measured along 147 °E and 155 °E in October–November 2012, 19 months after the accident. These measurements revealed subsurface peaks in radiocaesium concentrations at locations corresponding to two mode waters, Subtropical Mode Water and Central Mode Water. Mode water is a layer of almost vertically homogeneous water found over a large geographical area. Here we show that repeated formation of mode water during the two winter seasons after the Fukushima accident and subsequent outcropping into surface water transported radiocaesium downward and southward to subtropical regions of the North Pacific. The total amount of Fukushima-derived 134Cs within Subtropical Mode Water, decay-corrected to April 2011, was estimated to be 4.2 ± 1.1 PBq in October–November 2012. This amount of 134Cs corresponds to 22–28% of the total amount of 134Cs released to the Pacific Ocean. PMID:26915424

  12. Enhanced photoelectrochemical performance of WO3/Ti photoanode due to in situ formation of a thin interfacial composite layer

    NASA Astrophysics Data System (ADS)

    Lee, Won Jae; Shinde, Pravin S.; Go, Geun Ho; Doh, Chil Hoon

    2013-04-01

    Nanostructured WO3 thin films were prepared on titanium sheet substrates using a doctor blade technique. X-ray diffraction, Raman and field emission scanning electron microscopy studies revealed that the synthesized WO3 films are having monoclinic crystal structure, porous, polycrystalline with average grain size of ∼50 nm. The photoelectrochemical responses of WO3 films prepared on treated Ti sheets were recorded in 0.5 M H2SO4 electrolyte under simulated 100 mW/cm2 illumination. WO3 film prepared on polished Ti sheet showed considerable enhancement in photocurrent as compared to WO3 films made on unpolished and pre-oxidized Ti sheets. These results suggest that in situ formation of a thin WOx-TiOy interfacial composite layer and improved adhesion of WO3 nanoparticles owing to increased reactive sites on polished Ti substrate play a significant role in enhancing the photoresponse. Such photoanodes are potential candidates in photoelectrochemical water splitting system for hydrogen generation.

  13. Intrusion of Fukushima-derived radiocaesium into subsurface water due to formation of mode waters in the North Pacific

    NASA Astrophysics Data System (ADS)

    Kaeriyama, Hideki; Shimizu, Yugo; Setou, Takashi; Kumamoto, Yuichiro; Okazaki, Makoto; Ambe, Daisuke; Ono, Tsuneo

    2016-02-01

    The Fukushima Dai-ichi Nuclear Power Plant accident in March 2011 released radiocaesium (137Cs and 134Cs) into the North Pacific Ocean. Meridional transects of the vertical distribution of radiocaesium in seawater were measured along 147 °E and 155 °E in October-November 2012, 19 months after the accident. These measurements revealed subsurface peaks in radiocaesium concentrations at locations corresponding to two mode waters, Subtropical Mode Water and Central Mode Water. Mode water is a layer of almost vertically homogeneous water found over a large geographical area. Here we show that repeated formation of mode water during the two winter seasons after the Fukushima accident and subsequent outcropping into surface water transported radiocaesium downward and southward to subtropical regions of the North Pacific. The total amount of Fukushima-derived 134Cs within Subtropical Mode Water, decay-corrected to April 2011, was estimated to be 4.2 ± 1.1 PBq in October-November 2012. This amount of 134Cs corresponds to 22-28% of the total amount of 134Cs released to the Pacific Ocean.

  14. Oxide formation on NbAl{sub 3} and TiAl due to ion implantation of {sup 18}O

    SciTech Connect

    Hanrahan, R.J. Jr.; Verink, E.D. Jr.; Withrow, S.P.; Ristolainen, E.O.

    1993-12-31

    Surface modification by ion implantation of {sup 18}O ions was investigated as a technique for altering the high-temperature oxidation of aluminide intermetallic compounds and related alloys. Specimens of NbAl{sub 3} and TiAl were implanted to a dose of 1 {times} 10{sup 18} ions/cm{sup 2} at 168 keV. Doses and accelerating energies were calculated to obtain near-stoichiometric concentrations of oxygen. Use of {sup 18}O allowed the implanted oxygen profiles to be measured using secondary ion mass spectroscopy (SIMS). The near surface oxides formed were studied using x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy. Specimens were also examined using x-ray diffraction and SEM. This paper presents results for specimens examined in the as-implanted state. The oxide formed due to implantation is a layer containing a mixture of Nb or Ti and amorphous Al oxides.

  15. Osteogenesis Imperfecta due to Mutations in Non-Collagenous Genes-Lessons in the Biology of Bone Formation

    PubMed Central

    Marini, Joan C.; Reich, Adi; Smith, Simone M.

    2014-01-01

    Purpose of Review Osteogenesis imperfecta (OI), or “brittle bone disease”, has mainly been considered a bone disorder caused by collagen mutations. Within the last decade, however, a surge of genetic discoveries has created a new paradigm for OI as a collagen-related disorder, where autosomal dominant type I collagen defects cause most cases, while rare, mostly recessive forms are due to defects in genes whose protein products interact with collagen protein. This review is both timely and relevant in outlining the genesis, development and future of this paradigm shift in the understanding of OI. Recent Findings BRIL and PEDF defects cause types V and VI OI via defective bone mineralization, while defects in CRTAP, P3H1 and CyPB cause types VII-IX via defective collagen post-translational modification. Hsp47 and FKBP65 defects cause types X and XI OI via aberrant collagen crosslinking, folding and chaperoning, while defects in SP7, WNT1, TRIC-B and OASIS disrupt osteoblast development. Finally, absence of the type I collagen C-propeptidase BMP1 causes type XII OI due to altered collagen maturation/processing. Summary Identification of these multiple causative defects has provided crucial information for accurate genetic counseling, inspired a recently proposed functional grouping of OI types by shared mechanism to simplify current nosology, and should prod investigations into common pathways in OI. Such investigations could yield critical information on cellular and bone tissue mechanisms and translate to new mechanistic insight into clinical therapies for patients. PMID:25007323

  16. Combined inhibition of 20-hydroxyeicosatetraenoic acid formation and of epoxyeicosatrienoic acids degradation attenuates hypertension and hypertension-induced end-organ damage in Ren-2 transgenic rats

    PubMed Central

    Čertíková Chábová, Věra; Walkowska, Agnieszka; Kompanowska-Jezierska, Elzbieta; Sadowski, Janusz; Kujal, Petr; Vernerová, Zdena; Vaňourková, Zdenka; Kopkan, Libor; Kramer, Herbert J.; Falck, John R.; Imig, John D.; Hammock, Bruce D.; Vaněčková, Ivana; Červenka, Luděk

    2010-01-01

    Recent studies have shown that the renal cytochrome P-450 metabolites of arachidonic acid: the vasoconstrictor 20-hydroxyeicosatetraenoic acid (20-HETE), and the vasodilator epoxyeicosatrienoic acids (EETs) play an important role in the pathophysiology of angiotensin II (ANG II)-dependent forms of hypertension and the associated target organ damage. The present studies were performed in Ren-2 renin transgenic rats (TGR) to evaluate the effects of chronic selective inhibition of 20-HETE formation or elevation of the level of EETs, alone or in combination, on the course of hypertension and hypertension-associated end-organ damage. Both young (30 days of age) prehypertensive TGR and adult (190 days of age) TGR with established hypertension were examined. Normotensive Hannover Sprague-Dawley (HanSD) rats served as controls. The rats were treated with N-methylsulfonyl-12,12-dibromododec-11-enamide to inhibit 20-HETE formation and/or with N-cyclohexyl-N-dodecyl urea to inhibit soluble epoxide hydrolase and prevent degradation of EETs. Inhibition in TGR rats of 20-HETE formation combined with enhanced bioavailability of EETs attenuated the development of hypertension, cardiac hypertrophy, proteinuria, glomerular hypertrophy and sclerosis as well as renal tubulointerstitial injury. This was also associated with an attenuation of the responsiveness of the systemic and renal vascular beds to ANG II without modifying their responses to norepinephrine. Our data suggest that altered production and/or action of 20-HETE and EETs plays a permissive role in the development of hypertension and hypertension-associated end-organ damage in this model of ANG II-dependent hypertension. This information provides a basis for a search of new therapeutic approaches to the treatment of hypertension. PMID:20050826

  17. SUMO regulates p21Cip1 intracellular distribution and with p21Cip1 facilitates multiprotein complex formation in the nucleolus upon DNA damage.

    PubMed

    Brun, Sonia; Abella, Neus; Berciano, Maria T; Tapia, Olga; Jaumot, Montserrat; Freire, Raimundo; Lafarga, Miguel; Agell, Neus

    2017-01-01

    We previously showed that p21Cip1 transits through the nucleolus on its way from the nucleus to the cytoplasm and that DNA damage inhibits this transit and induces the formation of p21Cip1-containing intranucleolar bodies (INoBs). Here, we demonstrate that these INoBs also contain SUMO-1 and UBC9, the E2 SUMO-conjugating enzyme. Furthermore, whereas wild type SUMO-1 localized in INoBs, a SUMO-1 mutant, which is unable to conjugate with proteins, does not, suggesting the presence of SUMOylated proteins at INoBs. Moreover, depletion of the SUMO-conjugating enzyme UBC9 or the sumo hydrolase SENP2 changed p21Cip1 intracellular distribution. In addition to SUMO-1 and p21Cip1, cell cycle regulators and DNA damage checkpoint proteins, including Cdk2, Cyclin E, PCNA, p53 and Mdm2, and PML were also detected in INoBs. Importantly, depletion of UBC9 or p21Cip1 impacted INoB biogenesis and the nucleolar accumulation of the cell cycle regulators and DNA damage checkpoint proteins following DNA damage. The impact of p21Cip1 and SUMO-1 on the accumulation of proteins in INoBs extends also to CRM1, a nuclear exportin that is also important for protein translocation from the cytoplasm to the nucleolus. Thus, SUMO and p21Cip1 regulate the transit of proteins through the nucleolus, and that disruption of nucleolar export by DNA damage induces SUMO and p21Cip1 to act as hub proteins to form a multiprotein complex in the nucleolus.

  18. SUMO regulates p21Cip1 intracellular distribution and with p21Cip1 facilitates multiprotein complex formation in the nucleolus upon DNA damage

    PubMed Central

    Brun, Sonia; Abella, Neus; Berciano, Maria T.; Tapia, Olga; Jaumot, Montserrat; Freire, Raimundo; Lafarga, Miguel

    2017-01-01

    We previously showed that p21Cip1 transits through the nucleolus on its way from the nucleus to the cytoplasm and that DNA damage inhibits this transit and induces the formation of p21Cip1-containing intranucleolar bodies (INoBs). Here, we demonstrate that these INoBs also contain SUMO-1 and UBC9, the E2 SUMO-conjugating enzyme. Furthermore, whereas wild type SUMO-1 localized in INoBs, a SUMO-1 mutant, which is unable to conjugate with proteins, does not, suggesting the presence of SUMOylated proteins at INoBs. Moreover, depletion of the SUMO-conjugating enzyme UBC9 or the sumo hydrolase SENP2 changed p21Cip1 intracellular distribution. In addition to SUMO-1 and p21Cip1, cell cycle regulators and DNA damage checkpoint proteins, including Cdk2, Cyclin E, PCNA, p53 and Mdm2, and PML were also detected in INoBs. Importantly, depletion of UBC9 or p21Cip1 impacted INoB biogenesis and the nucleolar accumulation of the cell cycle regulators and DNA damage checkpoint proteins following DNA damage. The impact of p21Cip1 and SUMO-1 on the accumulation of proteins in INoBs extends also to CRM1, a nuclear exportin that is also important for protein translocation from the cytoplasm to the nucleolus. Thus, SUMO and p21Cip1 regulate the transit of proteins through the nucleolus, and that disruption of nucleolar export by DNA damage induces SUMO and p21Cip1 to act as hub proteins to form a multiprotein complex in the nucleolus. PMID:28582471

  19. Formation of a fibrin based gelatinous coat over repairing rat gastric epithelium after acute ethanol damage: interaction with adherent mucus.

    PubMed Central

    Sellers, L A; Allen, A; Bennett, M K

    1987-01-01

    A gelatinous coat, heterogeneous in appearance, was formed over damaged rat gastric mucosa recovering from acute ethanol injury. This coat, in places 1.6 mm thick (median thickness 680 microns), was 10 times thicker than the translucent layer of adherent mucus (median thickness 70 microns) covering the undamaged mucosa. Immunohistochemistry and periodic acid Schiff staining showed this gelatinous coat to be predominantly a fibrin gel with an exterior layer rich in mucus and necrotic cells. The plasma clotting time was significantly decreased in vitro by pig gastric mucus gel and soluble mucus glycoprotein (90% and 13% respectively) suggesting that in vivo the mucus layer remaining after epithelial damage could act as a template for fibrinogen-fibrin conversion. These results show that a fibrin based gelatinous coat, quite distinct from the adherent mucus layer and with considerable protective potential could be formed over the repairing rat gastric mucosa after acute ethanol damage. Images Fig. 1 Fig. 2 Fig. 4 Fig. 5 Fig. 6 Fig. 7 PMID:3653751

  20. [Cytogenetic damage to the corneal epithelium of mice due to the in vivo exposure to ionizing radiation with different levels of linear energy transfer].

    PubMed

    Vorozhtsova, S V; Bulynina, T M; Molokanov, A G; Ivanov, A A

    2015-01-01

    Damages to corneal epithelium cells were studied in mice irradiated by protons with the energies of 10, 25, 50 and 645 MeV, 60Co γ-quanta and accelerated ions of boron, carbon and neon with the energies of 7.5; 2.5 and 6.0 MeV/nucleon, respectively. X-rays (180 keV) were used as a standard radiation. Animals were exposed to a single dose in the range from 25 to 760 cGy. The mitotic index and aberrant mitoses were counted in corneal preparations in 24 hrs after irradiation. No matter the type of radiation, the mitotic index had an inverse dose dependence, i.e. the higher the dose, the lower the mitotic index. Exposure to all types of radiation resulted in a sharp increase in the number of chromosomal aberrations in the corneal epithelium; frequency of aberrations was a function of dose and type of radiation. The number of chromosomal aberrations displayed a peculiar direct dose dependence irrespective of type of radiation; however, heavy ions of carbon and boron are the most damaging to the cytogenetic apparatus of epithelial cells. Protons at the Bragg peak and ensuing fall, and of 50 MeV also contribute to the production of chromosomal aberrations as compared with sparsely ionizing gamma- and X-rays and high-energy protons with low linear energy transfer. Coefficients of relative biological effectiveness were calculated based on the mitotic index and evidence of aberrant mitosis.

  1. Disruption of the ECM33 gene in Candida albicans prevents biofilm formation, engineered human oral mucosa tissue damage and gingival cell necrosis/apoptosis.

    PubMed

    Rouabhia, Mahmoud; Semlali, Abdelhabib; Chandra, Jyotsna; Mukherjee, Pranab; Chmielewski, Witold; Ghannoum, Mahmoud A

    2012-01-01

    In this study we demonstrated that ΔCaecm33 double mutant showed reduced biofilm formation and causes less damage to gingival mucosa tissues. This was confirmed by the reduced level of necrotic cells and Bax/Bcl2 gene expression as apoptotic markers. In contrast, parental and Caecm33 mutant strains decreased basement membrane protein production (laminin 5 and type IV collagen). We thus propose that ECM33 gene/protein represents a novel target for the prevention and treatment of infections caused by Candida.

  2. Disruption of the ECM33 Gene in Candida albicans Prevents Biofilm Formation, Engineered Human Oral Mucosa Tissue Damage and Gingival Cell Necrosis/Apoptosis

    PubMed Central

    Rouabhia, Mahmoud; Semlali, Abdelhabib; Chandra, Jyotsna; Mukherjee, Pranab; Chmielewski, Witold; Ghannoum, Mahmoud A.

    2012-01-01

    In this study we demonstrated that ΔCaecm33 double mutant showed reduced biofilm formation and causes less damage to gingival mucosa tissues. This was confirmed by the reduced level of necrotic cells and Bax/Bcl2 gene expression as apoptotic markers. In contrast, parental and Caecm33 mutant strains decreased basement membrane protein production (laminin 5 and type IV collagen). We thus propose that ECM33 gene/protein represents a novel target for the prevention and treatment of infections caused by Candida. PMID:22665950

  3. Changes in the Physicochemical Properties of Piperine/β-Cyclodextrin due to the Formation of Inclusion Complexes

    PubMed Central

    Ezawa, Toshinari; Inoue, Yutaka; Tunvichien, Sujimon; Suzuki, Rina; Kanamoto, Ikuo

    2016-01-01

    Piperine (PP) is a pungent component in black pepper that possesses useful biological activities; however it is practically insoluble in water. The aim of the current study was to prepare a coground mixture (GM) of PP and β-cyclodextrin (βCD) (molar ratio of PP/βCD = 1/1) and subsequently evaluate the solubility of PP and physicochemical properties of the GM. DSC thermal behavior of the GM showed the absence of melting peak of piperine. PXRD profile of the GM exhibited halo pattern and no characteristic peaks due to PP and βCD were observed. Based on Job's plot, the PP/βCD complex in solution had a stoichiometric ratio of 1/1. Raman spectrum of the GM revealed scattering peaks assigned for the benzene ring (C=C), the methylene groups (CH2), and ether groups (C-O-C) of PP that were broaden and shifted to lower frequencies. SEM micrographs showed that particles in the GM were agglomerated and had rough surface, unlike pure PP and pure βCD particles. At 15 min of dissolution testing, the amount dissolved of PP in the GM was dramatically increased (about 16 times) compared to that of pure PP. Moreover the interaction between PP and βCD cavity was detected by 1H-1H NMR nuclear Overhauser effect spectroscopy NMR spectroscopy. PMID:26998357

  4. Functional MRI for characterization of renal perfusion impairment and edema formation due to acute kidney injury in different mouse strains

    PubMed Central

    Chen, Rongjun; Gutberlet, Marcel; Jang, Mi-Sun; Meier, Martin; Mengel, Michael; Hartung, Dagmar; Wacker, Frank; Rong, Song; Hueper, Katja

    2017-01-01

    Purpose The purpose was to characterize acute kidney injury (AKI) in C57BL/6 (B6)- and 129/Sv (Sv)-mice by noninvasive measurement of renal perfusion and tissue edema using functional MRI. Methods Different severities of AKI were induced in B6- and Sv-mice by renal ischemia reperfusion injury (IRI). Unilateral clamping of the renal pedicle for 35 min (moderate AKI) or 45 min (severe AKI) was done. MRI (7-Tesla) was performed 1, 7 and 28 days after surgery using a flow alternating inversion recovery (FAIR) arterial spin labeling (ASL) sequence. Maps of perfusion and T1-relaxation time were calculated. Relative MRI-parameters of the IRI kidney compared to the contralateral not-clipped kidney were compared between AKI severities and between mouse strains using unpaired t-tests. In addition, fibrosis was assessed by Masson Trichrome and collagen IV staining. Results After moderate AKI relative perfusion impairment was significantly higher in B6- than in Sv-mice at d7 (55±7% vs. 82±8%, p<0.05) and d28 (76±7% vs. 102±3%, p<0.01). T1-values increased in the early phase after AKI in both mouse strains. T1-increase was more severe after prolonged ischemia times of 45 min compared to 35 min in both mouse strains, measured in the renal cortex and outer stripe of outer medulla. Kidney volume loss (compared to the contralateral kidney) occurred already after 7 days but proceeded markedly towards 4 weeks in severe AKI. Early renal perfusion impairment was predictive for later kidney volume loss. The progression to chronic kidney disease (CKD) in the severe AKI model was similar in both mouse strains as revealed by histology. Conclusion Quantification of renal perfusion and tissue edema by functional MRI allows characterization of strain differences upon AKI. Renal perfusion impairment was stronger in B6- compared to Sv-animals following moderate AKI. Prolonged ischemia times were associated with more severe perfusion impairment and edema formation in the early phase and

  5. High risk of fistula formation in vacuum-assisted closure therapy in patients with open abdomen due to secondary peritonitis-a retrospective analysis.

    PubMed

    Mintziras, Ioannis; Miligkos, Michael; Bartsch, Detlef Klaus

    2016-08-01

    The aim of this study was to evaluate the efficacy of vacuum-assisted closure therapy in patients with open abdomen due to secondary peritonitis and to identify possible risk factors of fistula formation. The hospital OPS-database (time period 2005-2014) was searched to identify patients treated with an open abdomen due to secondary peritonitis, who underwent vacuum-assisted closure therapy. Medical records were retrospectively analyzed for patients' characteristics, cause of peritonitis, duration of vacuum therapy, number of relaparotomies, fascial closure rates, and risk factors of fistula formation. Forty-three patients (19 male, 24 female) with a median age of 65 years (range 24-90 years) were identified. The major cause of secondary peritonitis was anastomotic leakage after intestinal anastomosis or bowel perforation, the median APACHE II score was 11. Median duration of VAC treatment was 12 days (range 3-88 days). Twenty of 43 (47 %) patients died from septic complications. Delayed fascial closure was obtained by suturing in 20 of 43 patients (47 %). Overall 16 of 43 (37 %) patients developed enteroatmospheric fistulas. Re-explorations after starting VAC treatment and duration of VAC therapy were significantly associated with the occurrence of enteroatmospheric fistulas (p < 0.001). ROC curve analysis determined the optimal duration of VAC therapy to reduce the risk of fistula formation at 13 days. Long-term VAC treatment of patients with an open abdomen due to secondary peritonitis results in a relatively low fascial closure rate and a high risk of fistula formation.

  6. Scenario-based assessment of buildings' damage and population exposure due to earthquake-induced tsunamis for the town of Alexandria, Egypt

    NASA Astrophysics Data System (ADS)

    Pagnoni, G.; Armigliato, A.; Tinti, S.

    2015-12-01

    Alexandria is the second biggest city in Egypt with regards to population, is a key economic area in northern Africa and has very important tourist activity. Historical records indicate that it was severely affected by a number of tsunami events. In this work we assess the tsunami hazard by running numerical simulations of tsunami impact in Alexandria through the worst-case credible tsunami scenario analysis (WCTSA). We identify three main seismic sources: the western Hellenic Arc (WHA - reference event AD 365, Mw = 8.5), the eastern Hellenic Arc (EHA - reference event 1303, Mw = 8.0) and the Cyprus Arc (CA - hypothetical scenario earthquake with Mw = 8.0), inferred from the tectonic setting and from historical tsunami catalogues. All numerical simulations are carried out in two sea level conditions (mean sea level and maximum high-tide sea level) by means of the code UBO-TSUFD, developed and maintained by the Tsunami Research Team of the University of Bologna. Relevant tsunami metrics are computed for each scenario and then used to build aggregated fields such as the maximum flood depth and the maximum inundation area. We find that the case that produces the most relevant flooding in Alexandria is the EHA scenario, with wave heights up to 4 m. The aggregate fields are used for a building vulnerability assessment according to a methodology developed in the framework of the EU-FP6 project SCHEMA and further refined in this study, based on the adoption of a suitable building damage matrix and on water inundation depth. It is found that in the districts of El Dekhila and Al Amriyah, to the south-west of the port of Dekhila, over 12 000 (13 400 in the case of maximum high tide) buildings could be affected and hundreds of them could sustain damaging consequences, ranging from critical damage to total collapse. It is also found that in the same districts tsunami inundation covers an area of about 15 km2, resulting in more than 150 000 (165 000 in the case of maximum high

  7. Mineralogical and chemical assessment of concrete damaged by the oxidation of sulfide-bearing aggregates: Importance of thaumasite formation on reaction mechanisms

    SciTech Connect

    Rodrigues, A.; Duchesne, J.; Fournier, B.; Durand, B.; Rivard, P.; Shehata, M.

    2012-10-15

    Damages in concrete containing sulfide-bearing aggregates were recently observed in the Trois-Rivieres area (Quebec, Canada), characterized by rapid deterioration within 3 to 5 years after construction. A petrographic examination of concrete core samples was carried out using a combination of tools including: stereomicroscopic evaluation, polarized light microscopy, scanning electron microscopy, X-ray diffraction and electron microprobe analysis. The aggregate used to produce concrete was an intrusive igneous rock with different metamorphism degrees and various proportions of sulfide minerals. In the rock, sulfide minerals were often surrounded by a thin layer of carbonate minerals (siderite). Secondary reaction products observed in the damaged concrete include 'rust' mineral forms (e.g. ferric oxyhydroxides such as goethite, limonite (FeO (OH) nH{sub 2}O) and ferrihydrite), gypsum, ettringite and thaumasite. In the presence of water and oxygen, pyrrhotite oxidizes to form iron oxyhydroxides and sulphuric acid. The acid then reacts with the phases of the cement paste/aggregate and provokes the formation of sulfate minerals. Understanding both mechanisms, oxidation and internal sulfate attack, is important to be able to duplicate the damaging reaction in laboratory conditions, thus allowing the development of a performance test for evaluating the potential for deleterious expansion in concrete associated with sulfide-bearing aggregates.

  8. Ion beam damage assessment and waveguide formation induced by energetic Si-ion irradiation in lanthanum aluminate crystal

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Huang, Q.; Crespillo, M. L.; Qiao, M.; Liu, P.; Wang, X. L.

    2017-02-01

    Lanthanum aluminate (LaAlO3) crystal has emerged as one of the most valuable functional-materials, and its physical, electronic and optical properties strongly depend on the crystal structure, which can be easily altered in an irradiation environment and therefore affect the performance of LaAlO3-based devices. On the other hand, the preparation of LaAlO3 waveguide is also a scientific challenge for its potential application prospects in optoelectronics field. In this work, the damage evolution behavior of LaAlO3 crystal under Si-ion irradiation has been discussed in detail utilizing complementary characterization techniques, and then, single-mode waveguide of LaAlO3 crystal in the visible band can be obtained based on ion-irradiation-induced lattice damage behavior. Waveguide optical-coupling techniques are used to show its competitive features. Thus, novel optical waveguides with optimized features in LaAlO3 crystals can be tailored by a proper selection of ion mass, energy and fluence using the modification of the target material during ion irradiation process.

  9. The selection and application of loss control materials to minimize formation damage in gravel packed completions for a North Sea field

    SciTech Connect

    Hodge, R.M.; MacKinlay, W.M.; Landrum, W.R.

    1995-12-31

    This paper describes a laboratory evaluation of Loss Control Materials (LCM) commonly used to control fluid-loss during completions and workovers and the development of on-site Quality Control procedures for monitoring the performance of the LCM at the well site. In addition to the laboratory results, case histories are provided detailing application of the findings in gravel-packed completions. Conoco has recently completed five gravel-packed wells in the North Sea. The gravel packs were conducted in two stages: a perforation pre-pack and an annular gravel pack. During this completion procedure, LCM was used to wash excess gravel out of the casing following the pre-pack and to control fluid-loss. Analysis of the first completion indicated production was restricted through the completion. Subsequent evaluation of the completion procedure and LCM products indicated the most likely source of formation damage was residual LCM filter-cake. Laboratory tests monitoring fluid-loss control, rheology, and formation damage were performed on commonly-used LCM candidates. These candidates included sized-salt formulations, sized-calcium carbonate systems, and polymers from a variety of commercial suppliers. In addition to the evaluation of LCM products, remedial treatment options and a new delayed-release breaker were tested.

  10. Preventive effects of an original combination of grape seed polyphenols with amine fluoride on dental biofilm formation and oxidative damage by oral bacteria.

    PubMed

    Furiga, A; Roques, C; Badet, C

    2014-04-01

    To investigate the preventive effects of an original combination of a grape seed extract (GSE) with an amine fluoride (Fluorinol(®) ) on dental plaque formation and oxidative damage caused by oral bacteria. The antibacterial activity of the compounds was assessed using the broth macrodilution method, and their antiplaque activity was evaluated on a multispecies biofilm grown on saliva-coated hydroxyapatite discs. The effect on glucosyltransferases activity was analysed through reductions in the overall reaction and the quantity of insoluble glucan synthesized. The combination of 2000 μg ml(-1) of GSE with 10·2 mg ml(-1) of Fluorinol(®) significantly decreased the biofilm formation (up to 4·76 log10 of reduction) and inhibited by 97·4% the insoluble glucan synthesis by glucosyltransferases. The antioxidant activity of this combination, alone or incorporated into a formulated mouthwash (Eludril daily(®) ), was determined using the Trolox equivalent antioxidant capacity assay (TEAC), and both showed significantly greater antioxidant capacity than vitamin C. The GSE/Fluorinol(®) combination showed both a significant antiplaque activity and an important antioxidant capacity in vitro, without any bactericidal effects. This is, to our knowledge, the first report on the properties of an original combination of a polyphenolic extract with amine fluoride that could be used for the prevention of oral diseases and oxidative damage associated. © 2013 The Society for Applied Microbiology.

  11. Motor and sensory neuropathy due to myelin infolding and paranodal damage in a transgenic mouse model of Charcot–Marie–Tooth disease type 1C

    PubMed Central

    Lee, Samuel M.; Sha, Di; Mohammed, Anum A.; Asress, Seneshaw; Glass, Jonathan D.; Chin, Lih-Shen; Li, Lian

    2013-01-01

    Charcot–Marie–Tooth disease type 1C (CMT1C) is a dominantly inherited motor and sensory neuropathy. Despite human genetic evidence linking missense mutations in SIMPLE to CMT1C, the in vivo role of CMT1C-linked SIMPLE mutations remains undetermined. To investigate the molecular mechanism underlying CMT1C pathogenesis, we generated transgenic mice expressing either wild-type or CMT1C-linked W116G human SIMPLE. Mice expressing mutant, but not wild type, SIMPLE develop a late-onset motor and sensory neuropathy that recapitulates key clinical features of CMT1C disease. SIMPLE mutant mice exhibit motor and sensory behavioral impairments accompanied by decreased motor and sensory nerve conduction velocity and reduced compound muscle action potential amplitude. This neuropathy phenotype is associated with focally infolded myelin loops that protrude into the axons at paranodal regions and near Schmidt–Lanterman incisures of peripheral nerves. We find that myelin infolding is often linked to constricted axons with signs of impaired axonal transport and to paranodal defects and abnormal organization of the node of Ranvier. Our findings support that SIMPLE mutation disrupts myelin homeostasis and causes peripheral neuropathy via a combination of toxic gain-of-function and dominant-negative mechanisms. The results from this study suggest that myelin infolding and paranodal damage may represent pathogenic precursors preceding demyelination and axonal degeneration in CMT1C patients. PMID:23359569

  12. Reactivity of damaged pyrimidines: formation of a Schiff base intermediate at the glycosidic bond of saturated dihydrouridine.

    PubMed

    Jian, Yajun; Lin, Gengjie; Chomicz, Lidia; Li, Lei

    2015-03-11

    DNA glycosylases catalyze the first step of the base excision repair (BER) pathway. The chemistry used by these enzymes for deglycosylation has been largely considered as the chemistry of the oxocarbenium ion, e.g., direct rupture of the C1'-N1 bond resulting in an oxocarbenium ion intermediate. Here we present mechanistic studies revealing the 2'-deoxyribose isomerization and subsequent deglycosylation processes in two pyrimidine lesions: 5,6-dihydro-2'-deoxyuridine (dHdU) and 5,6-dihydrothymidine (dHT), formed via ionizing radiation damage to 2'-deoxycytidine and thymidine, respectively, under anoxic conditions. Acid or heat treatment of these two lesions leads to the production of two pairs of C1' epimers containing a pyranose and a furanose, respectively, indicating that both lesions favor the rupture of the C1'-O4' bond, resulting in a Schiff base intermediate at the N-glycosidic bond. Such a Schiff base intermediate was trapped and characterized by either Pd-catalyzed hydrogenation or thiol-mediated addition reaction. In contrast, in undamaged 2'-deoxyuridine and thymidine, reactions at elevated temperatures lead to the release of nucleobases most likely via the traditional oxocarbenium ion pathway. DFT calculations further support the experimental findings, suggesting that the oxocarbenium ion intermediate is responsible for the deglycosylation process if the integrity of the pyrimidine ring is maintained, while the Schiff base intermediate is preferred if the C5═C6 bond is saturated. Currently, the oxocarbenium ion pathway is indicated to be solely responsible for the deglycosylation in BER enzymes, however our results suggest an alternative Schiff base mechanism which may be responsible for the repair of saturated pyrimidine damages.

  13. Poly (ADP-Ribose) Polymerase is Involved in the Repair of DNA Damage Due to Sulfur Mustard by a Mechanism Other Than DNA Ligase I Activation

    DTIC Science & Technology

    2004-11-16

    agents including sulfur mustard (SM). We observed concurrent activation of PARP and DNA ligase in SM-exposed human epidermal keratinocytes (HEK...Previous reports from other laboratories suggested that DNA ligase activation could be due to its modification by PARP. In humans, there are three distinct...DNA ligases, I, II and IV of which DNA ligase I participates in DNA replication and repair. By metabolically labeling HEK using 3H-adenosine

  14. Acidification due to microbial dechlorination near a trichloroethene DNAPL is overcome with pH buffer or formate as electron donor: experimental demonstration in diffusion-cells.

    PubMed

    Philips, Jo; Maes, Nele; Springael, Dirk; Smolders, Erik

    2013-04-01

    Acidification due to microbial dechlorination of trichloroethene (TCE) can limit the bio-enhanced dissolution of TCE dense non-aqueous phase liquid (DNAPL). This study related the dissolution enhancement of a TCE DNAPL to the pH buffer capacity of the medium and the type of electron donor used. In batch systems, dechlorination was optimal at pH7.1-7.5, but was completely inhibited below pH6.2. In addition, dechlorination in batch systems led to a smaller pH decrease at an increasing pH buffer capacity or with the use of formate instead of lactate as electron donor. Subsequently, bio-enhanced TCE DNAPL dissolution was quantified in diffusion-cells with a 5.5 cm central sand layer, separating a TCE DNAPL layer from an aqueous top layer. Three different pH buffer capacities (2.9 mM-17.9 mM MOPS) and lactate or formate as electron donor were applied. In the lactate fed diffusion-cells, the DNAPL dissolution enhancement factor increased from 1.5 to 2.2 with an increase of the pH buffer capacity. In contrast, in the formate fed diffusion-cells, the DNAPL dissolution enhancement factor (2.4±0.3) was unaffected by the pH buffer capacity. Measurement of the pore water pH confirmed that the pH decreased less with an increased pH buffer capacity or with formate instead of lactate as electron donor. These results suggest that the significant impact of acidification on bio-enhanced DNAPL dissolution can be overcome by the amendment of a pH buffer or by applying a non acidifying electron donor like formate. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Early Stages of Hyaline Membrane Formation Detected in Alveolar Mouths in Diffuse Alveolar-Damage-Associated Diseases: A Detailed Immunohistochemical Study.

    PubMed

    Ohtsuki, Yuji; Fujita, Jiro; Yoshinouchi, Takeo; Enzan, Hideaki; Iguchi, Mitsuko; Lee, Gang-Hong; Furihata, Mutsuo

    2015-10-01

    To study the early stages of hyaline membrane (HM) formation, diffuse alveolar damage (DAD) was thoroughly investigated using immunohistochemical methods in 15 autopsy cases, which consisted of various types of interstitial pneumonias and pulmonary diseases derived from nonmalignant or malignant diseases. Alveolar mouths (AMs) that were presumed to be normal were ultrastructurally examined in detail, by using pulmonary tissues in the pneumothorax. It is interesting to note that during the initial stages of HM formation in AMs, fragmented eosinophilic masses were closely attached to AMs as irregular fragments or by a cap-like structure. The ultrastructure revealed some distance between the capillary spaces and surface epithelium of the AMs, indicating that the epithelial cells at the AMs might be often easily damaged even by minor stimuli; they can be considered as "locus minoris resistentiae." HMs were found to be formed initially at the site of AMs derived from fragmented eosinophilic masses in not only pulmonary but also extrapulmonary diseases, including both nonmalignant and malignant diseases. These irregular eosinophilic masses, representing the early shape of HMs, were immunohistochemically positive for the epithelial membrane antigens, namely, surfactant protein A and factor VIII antigen, and occasionally for KL-6 and cytokeratins. These results suggested that fragmented irregular masses represent the initial phase of HM formation. Five of 15 cases were focally negative for KL-6 at the initial irregular mass of HMs. Because KL-6 is one of the fundamental components of pulmonary surface elements, it needs to be studied further by detailed clinicopathological examination. © The Author(s) 2015.

  16. Examining food additives and spices for their anti-oxidant ability to counteract oxidative damage due to chronic exposure to free radicals from environmental pollutants

    NASA Astrophysics Data System (ADS)

    Martinez, Raul A., III

    The main objective of this work was to examine food additives and spices (from the Apiaceae family) to determine their antioxidant properties to counteract oxidative stress (damage) caused by Environmental pollutants. Environmental pollutants generate Reactive Oxygen species and Reactive Nitrogen species. Star anise essential oil showed lower antioxidant activity than extracts using DPPH scavenging. Dill Seed -- Anethum Graveolens -the monoterpene components of dill showed to activate the enzyme glutathione-S-transferase , which helped attach the antioxidant molecule glutathione to oxidized molecules that would otherwise do damage in the body. The antioxidant activity of extracts of dill was comparable with ascorbic acid, alpha-tocopherol, and quercetin in in-vitro systems. Black Cumin -- Nigella Sativa: was evaluated the method 1,1-diphenyl2-picrylhhydrazyl (DPPH) radical scavenging activity. Positive correlations were found between the total phenolic content in the black cumin extracts and their antioxidant activities. Caraway -- Carum Carvi: The antioxidant activity was evaluated by the scavenging effects of 1,1'-diphenyl-2-picrylhydrazyl (DPPH). Caraway showed strong antioxidant activity. Cumin -- Cuminum Cyminum - the major polyphenolic were extracted and separated by HPTLC. The antioxidant activity of the cumin extract was tested on 1,1'-diphenyl-2- picrylhydrazyl (DPPH) free radical scavenging. Coriander -- Coriandrum Sativum - the antioxidant and free-radical-scavenging property of the seeds was studied and also investigated whether the administration of seeds curtails oxidative stress. Coriander seed powder not only inhibited the process of Peroxidative damage, but also significantly reactivated the antioxidant enzymes and antioxidant levels. The seeds also showed scavenging activity against superoxides and hydroxyl radicals. The total polyphenolic content of the seeds was found to be 12.2 galic acid equivalents (GAE)/g while the total flavonoid content

  17. New petrophysical magnetic methods MACC and MAFM in permeability characterisation of petroleum reservoir rock cleaning, flooding modelling and determination of fines migration in formation damage

    NASA Astrophysics Data System (ADS)

    Ivakhnenko, O. P.

    2012-04-01

    Potential applications of magnetic techniques and methods in petroleum engineering and petrophysics (Ivakhnenko, 1999, 2006; Ivakhnenko & Potter, 2004) reveal their vast advantages for the petroleum reservoir characterisation and formation evaluation. In this work author proposes for the first time developed systematic methods of the Magnetic Analysis of Core Cleaning (MACC) and Magnetic Analysis of Fines Migration (MAFM) for characterisation of reservoir core cleaning and modelling estimations of fines migration for the petroleum reservoir formations. Using example of the one oil field we demonstrate results in application of these methods on the reservoir samples. Petroleum reservoir cores samples have been collected within reservoir using routine technique of reservoir sampling and preservation for PVT analysis. Immediately before the MACC and MAFM studies samples have been exposed to atmospheric air for a few days. The selected samples have been in detailed way characterised after fluid cleaning and core flooding by their mineralogical compositions and petrophysical parameters. Mineralogical composition has been estimated utilizing XRD techniques. The petrophysical parameters, such as permeability and porosity have been measured on the basis of total core analysis. The results demonstrate effectiveness and importance of the MACC and MAFM methods for the routine core analysis (RCAL) and the special core analysis (SCAL) in the reservoir characterisation, core flooding and formation damage analysis.

  18. K-134, a Phosphodiesterase 3 Inhibitor, Prevents Brain Damage by Inhibiting Thrombus Formation in a Rat Cerebral Infarction Model

    PubMed Central

    Yoshida, Hideo; Ashikawa, Yuka; Itoh, Shinsuke; Nakagawa, Takashi; Asanuma, Akimune; Tanabe, Sohei; Inoue, Yoshihiro; Hidaka, Hiroyoshi

    2012-01-01

    Background K-134 is a more potent antiplatelet drug with a selective inhibitory effect on phosphodiesterase 3 (PDE3) compared with its analogue, cilostazol. Objectives This study was performed to compare the ameliorating effects of K-134 and cilostazol on brain damage in an experimental photothrombotic cerebral infarction model. Methods and Results We investigated the effects of oral preadministration of PDE3 inhibitors in a rat stroke model established by photothrombotic middle cerebral artery (MCA) occlusion. K-134 significantly prolonged MCA occlusion time at doses >10 mg/kg, and reduced cerebral infarct size at 30 mg/kg in the stroke model (n = 12, 87.5±5.6 vs. 126.8±7.5 mm3, P<0.01), indicating its potent antithrombotic effect. On the other hand, the effects of cilostazol on MCA occlusion time and cerebral infarct size are relatively weak even at the high dosage of 300 mg/kg. Furthermore, K-134 blocked rat platelet aggregation more potently than cilostazol in vitro. Also in an arteriovenous shunt thrombosis model, K-134 showed an antithrombotic effect greater than cilostazol. Conclusions These findings suggest that K-134, which has strong antithrombotic activity, is a promising drug for prevention of cerebral infarction associated with platelet hyperaggregability. PMID:23110051

  19. K-134, a phosphodiesterase 3 inhibitor, prevents brain damage by inhibiting thrombus formation in a rat cerebral infarction model.

    PubMed

    Yoshida, Hideo; Ashikawa, Yuka; Itoh, Shinsuke; Nakagawa, Takashi; Asanuma, Akimune; Tanabe, Sohei; Inoue, Yoshihiro; Hidaka, Hiroyoshi

    2012-01-01

    K-134 is a more potent antiplatelet drug with a selective inhibitory effect on phosphodiesterase 3 (PDE3) compared with its analogue, cilostazol. This study was performed to compare the ameliorating effects of K-134 and cilostazol on brain damage in an experimental photothrombotic cerebral infarction model. We investigated the effects of oral preadministration of PDE3 inhibitors in a rat stroke model established by photothrombotic middle cerebral artery (MCA) occlusion. K-134 significantly prolonged MCA occlusion time at doses >10 mg/kg, and reduced cerebral infarct size at 30 mg/kg in the stroke model (n = 12, 87.5±5.6 vs. 126.8±7.5 mm(3), P<0.01), indicating its potent antithrombotic effect. On the other hand, the effects of cilostazol on MCA occlusion time and cerebral infarct size are relatively weak even at the high dosage of 300 mg/kg. Furthermore, K-134 blocked rat platelet aggregation more potently than cilostazol in vitro. Also in an arteriovenous shunt thrombosis model, K-134 showed an antithrombotic effect greater than cilostazol. These findings suggest that K-134, which has strong antithrombotic activity, is a promising drug for prevention of cerebral infarction associated with platelet hyperaggregability.

  20. A geminivirus betasatellite damages the structural and functional integrity of chloroplasts leading to symptom formation and inhibition of photosynthesis

    PubMed Central

    Bhattacharyya, Dhriti; Gnanasekaran, Prabu; Kumar, Reddy Kishore; Kushwaha, Nirbhay Kumar; Sharma, Veerendra Kumar; Yusuf, Mohd Aslam; Chakraborty, Supriya

    2015-01-01

    Geminivirus infection often causes severe vein clearing symptoms in hosts. Recently a betasatellite has emerged as a key regulator of symptom induction. To understand the host–betasatellite interactions in the process of symptom development, a systematic study was carried out involving symptoms induced by a betasatellite associated with radish leaf curl disease (RaLCB) in Nicotiana benthamiana. It has been found that βC1 protein localized to chloroplasts of host cells, and RaLCB lacking βC1, which failed to produce symptoms, had no effect on chloroplast ultrastructure. Vein flecking induced by transiently expressed βC1 was associated with chloroplast ultrastructure. In addition, the betasatellite down-regulates expression of genes involved in chlorophyll biosynthesis as well as genes involved in chloroplast development and plastid translocation. Interestingly, the expression of key host genes involved in chlorophyll degradation remains unaffected. Betasatellite infection drastically reduced the numbers of active reaction centres and the plastoquinol pool size in leaves exhibiting vein clearing symptoms. Betasatellite-mediated impediments at different stages of chloroplast functionality affect the photosynthetic efficiency of N. benthamiana. To the best of the authors’ knowledge, this is the first evidence of a chloroplast-targeting protein encoded by a DNA virus which induces vein clearing and structurally and functionally damages chloroplasts in plants. PMID:26113193

  1. A geminivirus betasatellite damages the structural and functional integrity of chloroplasts leading to symptom formation and inhibition of photosynthesis.

    PubMed

    Bhattacharyya, Dhriti; Gnanasekaran, Prabu; Kumar, Reddy Kishore; Kushwaha, Nirbhay Kumar; Sharma, Veerendra Kumar; Yusuf, Mohd Aslam; Chakraborty, Supriya

    2015-09-01

    Geminivirus infection often causes severe vein clearing symptoms in hosts. Recently a betasatellite has emerged as a key regulator of symptom induction. To understand the host-betasatellite interactions in the process of symptom development, a systematic study was carried out involving symptoms induced by a betasatellite associated with radish leaf curl disease (RaLCB) in Nicotiana benthamiana. It has been found that βC1 protein localized to chloroplasts of host cells, and RaLCB lacking βC1, which failed to produce symptoms, had no effect on chloroplast ultrastructure. Vein flecking induced by transiently expressed βC1 was associated with chloroplast ultrastructure. In addition, the betasatellite down-regulates expression of genes involved in chlorophyll biosynthesis as well as genes involved in chloroplast development and plastid translocation. Interestingly, the expression of key host genes involved in chlorophyll degradation remains unaffected. Betasatellite infection drastically reduced the numbers of active reaction centres and the plastoquinol pool size in leaves exhibiting vein clearing symptoms. Betasatellite-mediated impediments at different stages of chloroplast functionality affect the photosynthetic efficiency of N. benthamiana. To the best of the authors' knowledge, this is the first evidence of a chloroplast-targeting protein encoded by a DNA virus which induces vein clearing and structurally and functionally damages chloroplasts in plants. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  2. Nrf2 regulates an adaptive response protecting against oxidative damage following diquat-mediated formation of superoxide anion.

    PubMed

    Osburn, William O; Wakabayashi, Nobunao; Misra, Vikas; Nilles, Tricia; Biswal, Shyam; Trush, Michael A; Kensler, Thomas W

    2006-10-01

    Mouse embryonic fibroblasts derived from Nrf2-/- mice (N0) and Nrf2+/+ mice (WT) have been used to characterize both basal and diquat (DQ)-induced oxidative stress levels and to examine Nrf2 activation during exposure to DQ-generated superoxide anion. Microarray analysis revealed that N0 cells have similar constitutive mRNA expression of genes responsible for the direct metabolism of reactive oxygen species but decreased expression of genes responsible for the production of reducing equivalents, repair of oxidized proteins and defense against lipid peroxidation, compared to WT cells. Nonetheless, the basal levels of ROS flux and oxidative damage biomarkers in WT and N0 cells were not different. Diquat dibromide (DQ), a non-electrophilic redox cycling bipyridylium herbicide, was used to generate intracellular superoxide anion. Isolated mitochondria from both cell lines exposed to DQ produced equivalent amounts of ROS, indicating a similar cellular capacity to generate ROS. However, N0 cells exposed to DQ for 24-h exhibited markedly decreased cell viability and aconitase activity as well as increased lipid peroxidation and glutathione oxidation, relative to WT cells. 2',7'-Dichlorofluorescein fluorescence was not increased in WT and N0 cells after 30-min of DQ exposure. However, increased levels of ROS were detected in N0 cells but not WT cells after 13-h of DQ treatment. Additionally, total glutathione concentrations increased in WT, but not N0 cells following a 24-h exposure to DQ. DQ exposure resulted in activation of an antioxidant response element-luciferase reporter gene, as well as induction of Nrf2-regulated genes in WT, but not N0 cells. Thus the enhanced sensitivity of N0 cells does not reflect basal differences in antioxidative capacity, but rather an impaired ability to mount an adaptive response to sustained oxidative stress.

  3. Nrf2 Regulates an Adaptive Response Protecting Against Oxidative Damage Following Diquat-Mediated Formation of Superoxide Anion

    PubMed Central

    Osburn, William O.; Wakabayashi, Nobunao; Misra, Vikas; Nilles, Tricia; Biswal, Shyam; Trush, Michael A.; Kensler, Thomas W.

    2006-01-01

    Mouse embryonic fibroblasts derived from Nrf2 −/− mice (N0) and Nrf2 +/+ mice (WT) have been used to characterize both basal and diquat (DQ)-induced oxidative stress levels and to examine Nrf2 activation during exposure to DQ-generated superoxide anion. Microarray analysis revealed that N0 cells have similar constitutive mRNA expression of genes responsible for the direct metabolism of reactive oxygen species but decreased expression of genes responsible for the production of reducing equivalents, repair of oxidized proteins and defense against lipid peroxidation, compared to WT cells. Nonetheless, the basal levels of ROS flux and oxidative damage biomarkers in WT and N0 cells were not different. Diquat dibromide (DQ), a non-electrophilic redox cycling bipyridylium herbicide, was used to generate intracellular superoxide anion. Isolated mitochondria from both cell lines exposed to DQ produced equivalent amounts of ROS, indicating a similar cellular capacity to generate ROS. However, N0 cells exposed to DQ for 24-hr exhibited markedly decreased cell viability and aconitase activity as well as increased lipid peroxidation and glutathione oxidation, relative to WT cells. 2′,7′-Dichlorofluorescein fluorescence was not increased in WT and N0 cells after 30-min of DQ exposure. However, increased levels of ROS were detected in N0 cells but not WT cells after 13-hr of DQ treatment. Additionally, total glutathione concentrations increased in WT, but not N0 cells following a 24-hr exposure to DQ. DQ exposure resulted in activation of an antioxidant response element-luciferase reporter gene, as well as induction of Nrf2-regulated genes in WT, but not N0 cells. Thus the enhanced sensitivity of N0 cells does not reflect basal differences in antioxidative capacity, but rather an impaired ability to mount an adaptive response to sustained oxidative stress. PMID:16962985

  4. Global crop yield reductions due to surface ozone exposure: 2. Year 2030 potential crop production losses and economic damage under two scenarios of O 3 pollution

    NASA Astrophysics Data System (ADS)

    Avnery, Shiri; Mauzerall, Denise L.; Liu, Junfeng; Horowitz, Larry W.

    2011-04-01

    We examine the potential global risk of increasing surface ozone (O 3) exposure to three key staple crops (soybean, maize, and wheat) in the near future (year 2030) according to two trajectories of O 3 pollution: the Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios (IPCC SRES) A2 and B1 storylines, which represent upper- and lower-boundary projections, respectively, of most O 3 precursor emissions in 2030. We use simulated hourly O 3 concentrations from the Model for Ozone and Related Chemical Tracers version 2.4 (MOZART-2), satellite-derived datasets of agricultural production, and field-based concentration:response relationships to calculate crop yield reductions resulting from O 3 exposure. We then calculate the associated crop production losses and their economic value. We compare our results to the estimated impact of O 3 on global agriculture in the year 2000, which we assessed in our companion paper [Avnery et al., 2011]. In the A2 scenario we find global year 2030 yield loss of wheat due to O 3 exposure ranges from 5.4 to 26% (a further reduction in yield of +1.5-10% from year 2000 values), 15-19% for soybean (reduction of +0.9-11%), and 4.4-8.7% for maize (reduction of +2.1-3.2%) depending on the metric used, with total global agricultural losses worth 17-35 billion USD 2000 annually (an increase of +6-17 billion in losses from 2000). Under the B1 scenario, we project less severe but still substantial reductions in yields in 2030: 4.0-17% for wheat (a further decrease in yield of +0.1-1.8% from 2000), 9.5-15% for soybean (decrease of +0.7-1.0%), and 2.5-6.0% for maize (decrease of + 0.3-0.5%), with total losses worth 12-21 billion annually (an increase of +1-3 billion in losses from 2000). Because our analysis uses crop data from the year 2000, which likely underestimates agricultural production in 2030 due to the need to feed a population increasing from approximately 6 to 8 billion people between 2000 and 2030, our

  5. Mechanistic investigation of the formation damaging characteristics of mixed metal hydroxide drill-in fluids and comparison with polymer-base fluids

    SciTech Connect

    Fraser, L.J.; Reid, D.P.; Williamson, D.

    1995-12-31

    Mixed metal hydroxide (MMH) fluids are highly thixotropic and have shown exceptional abilities in the areas of hole cleaning, suspension, and maintenance of good hole gauge even through very poorly consolidated sandstones. When a drill-in fluid based on an MMH has been used in reservoir sections, the ease of cleanup and the production rates have both exceeded expectations. Results have been better than those achieved on offsets where more conventional fluids have been used. Laboratory results have also shown properly formulated MMH fluids to have a low potential for formation damage. The primary objectives of the laboratory project presented in this paper were to (1) investigate the mechanisms by which filter cakes develop against sandstone faces, (2) study the natures of the cakes produced with different types of drill-in fluids, and (3) investigate the implications for cake cleanup. In a group of unweighted fluids an MMH fluid was found to be unique in its ability to form a predominantly external cake. It was further shown that the strong interactions between the MMH crystals and the bentonite platelets, which interactions provide the characteristic high shear thinning and almost instantaneous gelling behavior of such fluids, also contribute to the avoidance of damaging internal cake formation. This study demonstrates by dynamic fluid-loss measurements, imaging of dried filter cakes using an SEM, and direct imaging of wet filter cakes using an environmental SEM that the fluid is able to form mineral bridges over pore throats in a wide range of reservoir rocks. The external cake formed by the MMH fluid is easily removed by wash fluids or simply by application of backpressure as occurs when a well is brought on to production.

  6. The laser driven short-term heating balloon catheter: Relation between the chronic neointimal hyperplasia formation and thermal damage to arterial smooth muscle cells.

    PubMed

    Shimazaki, Natsumi; Hayashi, Tomoaki; Kunio, Mie; Igami, Yuka; Arai, Tsunenori; Sakurada, Masami

    2010-01-01

    We proposed a novel laser-driven short-term heating angioplasty to realize restenosis-suppressive angioplasty for peripheral artery disease. In this study, we investigated the chronic intimal hyperplasia formation after the short-term heating dilatation in vivo, as well as the thermal damage calculation on arterial smooth muscle cells (SMCs). The prototype short-term heating balloon catheter with 5.0, 5.5, 6.0 mm φ in balloon diameter and 25 mm in balloon length were employed. The short-term heating dilatation was performed in porcine iliac arteries with dilatation conditions of 75°C (N=4) and 65°C (N=5) as peak balloon temperature, 18 ± 4s as heating duration, 3.5 atm as balloon dilatation pressure. Four weeks after the balloon dilatation, the balloon-dilated artery segments were extracted and were stained with HE and picrosirius red for histological observation. In the case of 75°C as the peak balloon temperature, neointimal hyperplasia formation was significantly reduced. In this case, the SMCs density in the artery media measured from the HE-stained specimen was 20% lower than that in the reference artery. According to the thermal damage calculation, it was estimated that the SMCs lethality in artery media after the short-term heating angioplasty was 20% in the case of 75°C as the peak balloon temperature. We demonstrated that the short-term heating dilatation reduced the number of SMCs in artery media. We think this SMCs reduction might contribute to the suppression of chronic neointimal hyperplasia.

  7. The Effects of Topically Applied Glycolic Acid and Salicylic Acid on Ultraviolet Radiation-Induced Erythema, DNA Damage and Sunburn Cell Formation in Human Skin

    PubMed Central

    Kornhauser, Andrija; Wei, Rong-Rong; Yamaguchi, Yuji; Coelho, Sergio G.; Kaidbey, Kays; Barton, Curtis; Takahashi, Kaoruko; Beer, Janusz Z.; Miller, Sharon A.; Hearing, Vincent J.

    2009-01-01

    Background α-Hydroxy acids (αHA) are reported to reduce signs of aging in the skin and are widely used cosmetic ingredients. Several studies suggest that αHA can increase the sensitivity of skin to ultraviolet radiation. More recently, β-hydroxy acids (βHA), or combinations of αHA and βHA have also been incorporated into antiaging skin care products. Concerns have also arisen about increased sensitivity to ultraviolet radiation following use of skin care products containing β-HA. Objective To determine whether topical treatment with glycolic acid, a representative αHA, or with salicylic acid, a βHA, modifies the short-term effects of solar simulated radiation (SSR) in human skin. Methods Fourteen subjects participated in this study. Three of the four test sites on the mid-back of each subject were treated daily Monday - Friday, for a total of 3.5 weeks, with glycolic acid (10%), salicylic acid (2%), or vehicle (control). The fourth site received no treatment. After the last treatment, each site was exposed to SSR, and shave biopsies from all 4 sites were obtained. The endpoints evaluated in this study were erythema (assessed visually and instrumentally), DNA damage and sunburn cell formation. Results Treatment with glycolic acid resulted in increased sensitivity of human skin to SSR, measured as an increase in erythema, DNA damage and sunburn cell formation. Salicylic acid did not produce significant changes in any of these biomarkers. Conclusions Short-term topical application of glycolic acid in a cosmetic formulation increased the sensitivity of human skin to SSR, while a comparable treatment with salicylic acid did not. PMID:19411163

  8. Global Crop Yield Reductions due to Surface Ozone Exposure: Crop Production Losses and Economic Damage in 2000 and 2030 under Two Future Scenarios of O3 Pollution

    NASA Astrophysics Data System (ADS)

    Avnery, S.; Mauzerall, D. L.; Liu, J.; Horowitz, L. W.

    2011-12-01

    Field studies demonstrate that exposure to elevated concentrations of surface ozone (O3) may cause substantial reductions in the agricultural yields of many crops. As emissions of O3 precursors rise in many parts of the world over the next few decades, yield reductions from O3 exposure may increase the challenges of feeding a global population projected to grow from approximately 6 to 8 billion people between 2000 and 2030. This study estimates global yield reductions of three key staple crops (soybean, maize, and wheat) due to surface ozone exposure in 2000 and 2030 according to two trajectories of O3 pollution: the Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios (IPCC SRES) A2 and B1 storylines, which represent upper- and lower-boundary projections, respectively, of most O3 precursor emissions in 2030. Our results indicate that year 2000 O3-induced global yield reductions ranged, depending on the O3 exposure metric used, from 3.9-15% for wheat, 8.5-14% for soybean, and 2.2-5.5% for maize. Global crop production losses totaled 79-121 million metric tons, worth 11-18 billion annually (USD2000). In the 2030-A2 scenario we find global O3-induced yield loss of wheat to be 5.4-26% (a further reduction in yield of +1.5-10% from year 2000 values), 15-19% for soybean (reduction of +0.9-11%), and 4.4-8.7% for maize (reduction of +2.1-3.2%) depending on the metric used, with total global agricultural losses worth 17-35 billion USD2000 annually (an increase of +6-17 billion in losses from 2000). Under the 2030-B1 scenario, we project less severe but still substantial reductions in yields: 4.0-17% for wheat (a further decrease in yield of +0.1-1.8% from 2000), 9.5-15% for soybean (decrease of +0.7-1.0%), and 2.5-6.0% for maize (decrease of+ 0.3-0.5%), with total losses worth 12-21 billion annually (an increase of +$1-3 billion in losses from 2000). Because our analysis uses crop data from the year 2000, which likely underestimates agricultural

  9. Therapeutic Effect of Human Adipose Tissue-Derived Mesenchymal Stem Cells in Experimental Corneal Failure Due to Limbal Stem Cell Niche Damage.

    PubMed

    Galindo, Sara; Herreras, José M; López-Paniagua, Marina; Rey, Esther; de la Mata, Ana; Plata-Cordero, María; Calonge, Margarita; Nieto-Miguel, Teresa

    2017-10-01

    Limbal stem cells are responsible for the continuous renewal of the corneal epithelium. The destruction or dysfunction of these stem cells or their niche induces limbal stem cell deficiency (LSCD) leading to visual loss, chronic pain, and inflammation of the ocular surface. To restore the ocular surface in cases of bilateral LSCD, an extraocular source of stem cells is needed to avoid dependence on allogeneic limbal stem cells that are difficult to obtain, isolate, and culture. The aim of this work was to test the tolerance and the efficacy of human adipose tissue-derived mesenchymal stem cells (hAT-MSCs) to regenerate the ocular surface in two experimental models of LSCD that closely resemble different severity grades of the human pathology. hAT-MSCs transplanted to the ocular surface of the partial and total LSCD models developed in rabbits were well tolerated, migrated to inflamed tissues, reduced inflammation, and restrained the evolution of corneal neovascularization and corneal opacity. The expression profile of the corneal epithelial cell markers CK3 and E-cadherin, and the limbal epithelial cell markers CK15 and p63 was lost in the LSCD models, but was partially recovered after hAT-MSC transplantation. For the first time, we demonstrated that hAT-MSCs improve corneal and limbal epithelial phenotypes in animal LSCD models. These results support the potential use of hAT-MSCs as a novel treatment of ocular surface failure due to LSCD. hAT-MSCs represent an available, non-immunogenic source of stem cells that may provide therapeutic benefits in addition to reduce health care expenses. Stem Cells 2017;35:2160-2174. © 2017 AlphaMed Press.

  10. 3-Nitrobenzanthrone (3-NBA) induced micronucleus formation and DNA damage in human hepatoma (HepG2) cells.

    PubMed

    Lamy, Evelyn; Kassie, Fekadu; Gminski, Richard; Schmeiser, Heinz H; Mersch-Sundermann, Volker

    2004-01-15

    3-Nitrobenzanthrone (3-NBA), identified in diesel exhaust and in airborne particulate matter, is a potent mutagen in Salmonella, induces micronuclei formation in mice and in human cells and DNA adducts in rats. In the present study, we investigated the genotoxic potency of 3-NBA in human HepG2 cells using the micronucleus (MN) assay and the single cell gel electrophoresis (SCGE). 3-NBA caused a genotoxic effect at concentrations > or =12 nM in both assays. In the micronucleus assay, we found 98.7+/-10.3 MN/1000 BNC at a concentration of 100 nM 3-NBA in comparison to 27.3+/-0.6 MN/1000 BNC with the negative control. At the same concentration, the DNA-migration (SCGE) showed an Olive tail moment (OTM) of 2.7+/-0.45 and %DNA in the tail of 8.28+/-0.76; OTM and %DNA in the tail of cells treated with the negative control were 0.73+/-0.08 and 2.81+/-0.30, respectively. The results are discussed under consideration of former studies.

  11. Radiation-induced surge of macrophage foam cell formation, oxidative damage, and cytokine release is attenuated by a nanoformulation of curcumin.

    PubMed

    Soltani, Behrooz; Bodaghabadi, Narges; Ghaemi, Nasser; Sadeghizadeh, Majid

    2017-03-01

    the expression of SR-A and ABCA1 genes, seemed to be independent of its antioxidant effect, since they were still observed in BSO-pretreated macrophages, depleted of GSH. DNC treatment suppresses IR-induced oxidative damage, inflammation, and foam cell formation in macrophages through multiple mechanisms.

  12. Thermal properties of Central Aare granite for temperatures up to 500°C: Irreversible changes due to thermal crack formation

    NASA Astrophysics Data System (ADS)

    Kant, Michael A.; Ammann, Jens; Rossi, Edoardo; Madonna, Claudio; Höser, Dragana; Rudolf von Rohr, Philipp

    2017-01-01

    Thermal diffusivity, heat capacity, and thermal conductivity of Central Aare granite are reported in the temperature range from 25°C to 500°C. Each rock sample underwent three consecutive heating and cooling cycles. Significant irreversible changes in the properties due to thermal crack formation could be observed. After the first thermal cycle, both thermal diffusivity and conductivity dropped to about 75% of the initial value at room temperature, whereas the heat capacity did not show an irreversible decay. For subsequent thermal cycles, no further permanent changes of the investigated properties could be observed. From the conducted measurements, accurate correlations are derived, offering a platform for precise high-temperature experiments and other research on Central Aare granite and similar granitic rocks. The report shows that the assumption of constant thermal properties leads to significant inaccuracies at elevated temperatures, especially if thermal cycles are present.

  13. [Chronic Heart Failure Due to Formation of Giant Left Ventricular Pseudoaneurysm After Painless Myocardial Infarction in a Female Patient With Diabetes].

    PubMed

    Katkova, L A; Furman, N V; Dolotovskaya, P V; Dovgalevsky, Ya P; Sakharova, N K; Panteleeva, E A; Parshina, E A

    2016-09-01

    Rupture of the free wall of the left ventricle with the formation of a false aneurysm (pseudoaneurysm, PA) - is a rare complication of acute myocardial infarction. Given the high risk of rupture of the PA and other life-threatening consequences (progressive heart failure, thromboembolic events), as well as the absence of pathognomonic signs and the difficulty in determining treatment strategy (feasibility and timing of surgery), early diagnosis of this complication appears to be especially important. We present here an overview of literature data on prevalence, specific features of diagnostics, and problems related to selection of method of treatment of PA. A case f congestive heart failure due to PA of the left ventricle as a result of painless myocardial infarction in 65-year-old patient with diabetes is also presented.

  14. Formation of DNA-damaging N-nitroso compounds from the interaction of calcium-channel blockers with nitrite.

    PubMed

    Martelli, Antonietta; Robbiano, Luigi; Grossi, Sarah; Mattioli, Francesca; Brambilla, Giovanni

    2007-09-05

    A large number of drugs have been shown to react with nitrite to give genotoxic-carcinogenic N-nitroso compounds (NOC). However, the majority of drugs remain to be examined in this respect, among which calcium-channel blockers, all theoretically nitrosatable and widely used in the therapy of hypertension and other cardiovascular diseases. In this preliminary investigation, seven calcium-channel blockers have been examined either for their in vitro nitrosation according to the procedure recommended by the WHO, or for occurrence of liver DNA fragmentation, as detected by the Comet assay, in rats given by gavage 1/2 LD50 of the drug and 80 mg/kg of sodium nitrite. After 6h incubation the yields of NOC formed in vitro from nicardipine, nifedipine, nimodipine and nitrendipine ranged from 37 to 45% of the theoretical one, whereas the yields of NOC formed from diltiazem, gallopamil and verapamil ranged from 2 to 5%. In vivo, as compared with the effect of the same dose of the drug alone, a significant increase of both tail length and tail moment, indicative of an increased frequency of DNA single-strand breaks and alkali-labile sites, was produced in rat liver DNA by the administration with nitrite of gallopamil, nifedipine, nimodipine and nitrendipine, the ratio [tail length of drug+NaNO(2)/tail length of drug alone] being 3.2 for nimodipine, 3.1 for gallopamil 2.2 for nifedipine, and 2.1 for nitrendipine. Even if present, the increase in the degree of DNA fragmentation did not reach the statistical significance in rats given with nitrite nicardipine, diltiazem and verapamil. Further studies should be performed to investigate the formation of NOC in conditions simulating those occurring in the stomach of humans treated with a therapeutic dose, and to quantitate their genotoxic potency.

  15. In vitro effects of fluor-hydroxyapatite, fluorapatite and hydroxyapatite on colony formation, DNA damage and mutagenicity.

    PubMed

    Jantová, S; Theiszová, M; Letasiová, S; Birosová, L; Palou, T M

    2008-04-30

    The number of biomaterials used in biomedical applications has rapidly increased in the past two decades. Fluorapatite (FA) is one of the inorganic constituents of bone or teeth used for hard-tissue repairs and replacements. Fluor-hydroxyapatite (FHA) is a new synthetically prepared composite that in its structure contains the same molecular concentration of OH(-) groups and F(-) ions. The aim of this experimental investigation was to evaluate cytotoxic, genotoxic and mutagenic effects of FHA and FA eluates on Chinese hamster V79 cells and to compare them with the effects of hydroxyapatite (HA) eluate. Cytotoxicity of the biomaterials tested was evaluated by use of the cell colony-formation assay and by direct counting of the cells in each colony. Genotoxicity was assessed by single-cell gel electrophoresis (comet assay) and mutagenicity was evaluated by the Hprt gene-mutation assay and in bacterial mutagenicity tests using Salmonella typhimurium TA100. The results show that the highest test concentrations of the biomaterials (100% and 75% eluates) induced very weak inhibition of colony growth (about 10%). On the other hand, the reduction of cell number per colony induced by these concentrations was in the range from 43% to 31%. The comet assay showed that biomaterials induced DNA breaks, which increased with increasing test concentrations in the order HA

  16. Mitigation of environmental impacts due to ghat road formation in Palamalai Hills, South India, by optimizing cut and fill volumes using GPS and GIS techniques.

    PubMed

    Arulmozhi, R; Subramani, T; Sukumar, S

    2015-01-01

    Formation of new roads generally brings about adverse impact on the environment, and in the case of hill roads, the impact is diverse and effective measures are required to mitigate it. The common problems in hill road formation are tree cutting, destruction of canopies, change in land use pattern, soil erosion, slope instability, induced landslides, invasion of foreign species, and so on. Removal of trees and vegetations causes rapid soil erosion, landslides, and invasion of foreign species posing danger to the survival of weak native species. Dumping of surplus earth materials on the valley side poses a significant threat to the environment as it would cause induced landslides. Using the cut earth for filling in road formation and dumping, the surplus cut earth in safe locations will reduce environmental degradation considerably. Conventionally, hill road alignments are finalized using traditional survey methods using ghat tracer, compass, and leveling surveys which require enormous complicated field and office works. Any revision to reduce the quantum of earthwork is difficult in this method due to its complex nature. In the present study at Palamalai Hills, South India, an alignment for a length of 7.95 km was prepared by traditional methods using ghat tracer and total station instruments for survey works. The earthwork quantities were ascertained from the longitudinal profile of the alignment. A GPS survey was also conducted along the alignment to examine its utility in alignment modification. To modify the stretches, where the earthwork cutting and filling are above normal and unbalanced and result in surplus earth, repeated GPS surveys were conducted along different paths to optimize the earthwork. The earthwork quantities of the original alignment were analyzed, and its correlation with environmental effect and the usefulness of the GPS survey in this task are presented in this paper.

  17. Study of crater formation and its characteristics due to impact of a cluster projectile on a metal surface by molecular dynamics approach

    NASA Astrophysics Data System (ADS)

    Naspoori, Srujan Kumar; Kammara, Kishore K.; Kumar, Rakesh

    2017-04-01

    Impingement of energetic particles/ions on material surfaces is of great interest as these impacts give rise to various interesting phenomena, such as sputtering, back-scattering, crater formation, emission of electrons and photons from material surfaces etc. Surface erosion occurring in the plasma-facing material of nuclear fusion reactors reduce their performance and this motivated the course of the current work in understanding the underlying physics of solid-particle interactions. In the present work, we have studied sputtering, crater formation and its characteristics on the surface of a plasma-facing material due to the impact of a low to high energy dust particle (a conglomerate of a few to a thousand atoms) using the molecular dynamics method. Sputtering yield, excavated atoms from the crater, crater depth, height of crater rim, radius and aspect ratio of the crater are calculated for a range of incident energies (10 eV to 10 keV), and the variation of these parameters with varying size (formed of 14, 32, 64 atoms) of dust particle at different temperatures of the target material are computed.

  18. Hypochlorite-induced damage to proteins: formation of nitrogen-centred radicals from lysine residues and their role in protein fragmentation.

    PubMed Central

    Hawkins, C L; Davies, M J

    1998-01-01

    Stimulated monocytes and neutrophils generate hypochlorite (HOCl) via the release of the enzyme myeloperoxidase and hydrogen peroxide. HOCl damages proteins by reaction with amino acid side-chains or backbone cleavage. Little information is available about the mechanisms and intermediates involved in these reactions. EPR spin trapping has been employed to identify radicals on proteins, peptides and amino acids after treatment with HOCl. Reaction with HOCl gives both high- and low-molecular-mass nitrogen-centred, protein-derived radicals; the yield of the latter increases with both higher HOCl:protein ratios and enzymic digestion. These radicals, which arise from lysine side-chain amino groups, react with ascorbate, glutathione and Trolox. Reaction of HOCl-treated proteins with excess methionine eliminates radical formation, which is consistent with lysine-derived chloramines (via homolysis of N-Cl bonds) being the radical source. Incubation of HOCl-treated proteins, after removal of excess oxidant, gives rise to both nitrogen-centred radicals, over a period of hours, and time-dependent fragmentation of the protein. Treatment with excess methionine or antioxidants (Trolox, ascorbate, glutathione) protects against fragmentation; urate and bilirubin do not. Chloramine formation and nitrogen-centred radicals are therefore key species in HOCl-induced protein fragmentation. PMID:9620862

  19. Cretaceous to Miocene thrusting and wrenching along the central South Carpathians due to a corner effect during collision and orocline formation

    NASA Astrophysics Data System (ADS)

    Ratschbacher, Lothar; Linzer, Hans-Gert; Moser, Franz; Strusievicz, Robert-Octavian; Bedelean, Horia; Har, Nicolae; Mogoş, Petru-Adrian

    1993-08-01

    Field studies in the Romanian South Carpathians (longitude 22.5° to 24.2°E and latitude 45.2° to 45.6°N) demonstrate (1) Cretaceous top-to-NE shearing parallel to the present strike of the thrust system connected with coaxial flattening within the generally northwest dipping foliation, (2) Paleogene ductile-brittle dextral wrenching, E-W compression (σ1: 87±15°), and basin formation (Petroşani basin) along the Cerna-Jiu fault system, (3) large-scale Miocene dextral wrenching along the northern margin of Moesia (σ1: 143±16°), and (4) probably Pliocene-early Pleistocene N-S compression (σ1: 205±25°). We discuss the tectonics of the South Carpathians stressing the corner effect of the Moesian foreland promontory during convergence and formation of the Carpathian orocline. Up to the late Early Cretaceous, subduction of oceanic crust was active between Europe-Moesia on one side and East Carpathia-Rhodopia on the other side. Collision and intracontinental deformation occurred during the late Early and Late Cretaceous. The pinning of the thrust front at the western tip of Moesia and the foreland recess north of it caused superposition of thrusting and wrenching during collision and lateral translation, tangential stretching during orocline formation, and spreading into the recess. Further convergence during the early Tertiary resulted in dislocation of the previously welded East Carpathian-Rhodopian and Moesian fragments along the Cerna-Jiu fault system and the further northeast translation of the western segment. The intramontane Petroşani basin opened as a northeasterly propagating, transient pull-apart structure along the Cerna-Jiu fault system, which acquired a curved, northwesterly convex, transtensional trace due to the shape of the Moesian promontory. Tightening of the Carpathian orocline and/or rearrangement of the microplate geometry during the formation of the Pannonian basin system led to large-scale dextral wrenching along the northern margin of

  20. 3(omega) Damage: Growth Mitigation

    SciTech Connect

    Kozlowski, M; Demos, S; Wu, Z-L; Wong, J; Penetrante, B; Hrubesh, L

    2001-02-22

    prevailing hypothesis for the growth mechanism of laser-initiated damage involves a synergism of some means for absorption of 3{omega} light at the damage site and local field enhancement due to cracks. A proposed mechanism for damage growth involves an initial damage at a precursor resulting in the transformation of basically non-absorbing SiO{sub 2} to form an absorbing layer of d-SiOx. In this context d-SiOx implies SiO{sub 2} modified in terms of either the formation of other stoichiometries (eg., SiO, Si, or more generally SiOx with 0due to cracks. The FY00 effort continued the identification of the absorbing species and the characterization of damage morphology while emphasizing the development of growth mitigation techniques directed at removing both the absorbing species and the cracks. We applied a variety of analytical tools to characterize the damage morphology, including; photoluminescence (PL) spectroscopy, optical and photothermal microscopies, high resolution transmission electron microscopy (TEM) and electron-spin-resonance (ESR) spectroscopy, x-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), x-ray micro-tomography (XMT) and cathodo-luminescence (CL). The objective of the surface damage mitigation effort is to experimentally validate methods that could effectively stop the growth of 3{omega} laser-initiated damage. A specific goal is to obtain data and information on successful methods for fused silica optics, which would be sufficient to enable the down-selection to a single approach. Future effort could then be focused on developing a primary method for actual implementation on NIF. It is also the intent of this study to prioritize the remaining successful methods, so that there will be a back-up selection if the primary method fails

  1. [Activation of deoxyribonucleotide synthesis by radioprotectants and antioxidants as a key stage in formation of body resistance to DNA-damaging factors].

    PubMed

    Sharygin, V L; Pulatova, M K; Shliakova, T G; Mitrokhin, Iu I; Todorov, I N

    2005-01-01

    -term administration of high antioxidant doses inhibited synthesis of dNTPs, DNA, and proteins. Radioprotectants and antioxidants affected the pool of blood protein Fe3+-transferrin controlling the synthesis of iron-containing ribonucleotide reductase activity in hematopoietic organs, and hence, the iron-dependent stage in DNA synthesis--dNTP synthesis. Activation of protein synthesis in organs by the studied substances increased the pools of Fe3+-transferrin and Cu2+-ceruloplasmin in the blood, which activated dNTP and DNA synthesis. Activated synthesis of dNTP, DNA, and proteins in the organs and increased pools of studied plasma proteins underlay the formation of body resistance to DNA-damaging factors.

  2. Permeability decline due to flow of dilute suspensions through porous media

    SciTech Connect

    Nasr-El-Din, H.A.

    1996-12-31

    Suspension flow in porous media is encountered in many industrial applications. In the oil industry, suspended solids present in injected waters cart cause significant damage around the wellbore or deep in the formation. Depending on tire physical properties of tire solid particles, the porous medium, and operating conditions, solids can form external or internal filter cake, or just flow through the media without causing any damage. External filter cake formation causes a fast and sharp drop in permeability or injectivity of the formation. Reversing the flow direction can recover some of the damaged permeability. Internal filter cake formation cases a gradual or steady drop in permeability. Reversing the flow direction will not recover tire damaged permeability. Increasing solids concentration or particle size will cause more damage to formation. Injection of low-salinity water into sandstone reservoirs can trigger fines migration and clay swelling. Both factors can damage the formation. Injection of water that is incompatible with the formation brine may cause precipitation of insoluble sulfates that cart plug the formation. Stimulation (or acidizing) the formation cart also produce solid particles that can damage the formation. Corrosion by-products (e.g., iron sulfide) cart block the flow paths and reduce the permeability of the formation. Many experimental and modeling studies to predict formation damage due to flow of suspensions in porous media are discussed in this chapter. Solids can be present in injected waters or be generated in the formation. More research is needed to predict flow of suspensions in porous media when solid particles invade and are generated in tire formation simultaneously. 71 refs., 19 figs.

  3. Determination of oxidative DNA base damage by gas chromatography-mass spectrometry. Effect of derivatization conditions on artifactual formation of certain base oxidation products.

    PubMed

    England, T G; Jenner, A; Aruoma, O I; Halliwell, B

    1998-10-01

    GC-MS is a widely used tool to measure oxidative DNA damage because of its ability to identify a wide range of base modification products. However, it has been suggested that the derivatization procedures required to form volatile products prior to GC-MS analysis can sometimes produce artifactual formation of certain base oxidation products, although these studies did not replicate previously-used reaction conditions, e.g. they failed to remove air from the derivatization vials. A systematic examination of this problem revealed that levels of 8-hydroxyguanine, 8-hydroxyadenine, 5-hydroxycytosine and 5-(hydroxymethyluracil) in commercial calf thymus DNA determined by GC-MS are elevated by increasing the temperature at which derivatization is performed in our laboratory. In particular, 8-hydroxyguanine levels after silylation at 140 degrees C were raised 8-fold compared to derivatization at 23 degrees C. Experiments on the derivatization of each undamaged base revealed that the artifactual oxidation of guanine, adenine, cytosine and thymine respectively was responsible. Formation of the above products was potentiated by not purging with nitrogen prior to derivatization. Increasing the temperature to 140 degrees C or allowing air to be present during derivatization did not significantly increase levels of the other oxidized bases measured. This work suggests that artifactual oxidation during derivatization is restricted to certain products (8-hydroxyguanine, 8-hydroxyadenine, 5-hydroxycytosine and 5-[hydroxymethyluracil]) and can be decreased by reducing the temperature of the derivatization reaction to 23 degrees C and excluding as much air possible. Despite some recent reports, we were easily able to detect formamidopyrimidines in acid-hydrolyzed DNA. Artifacts of derivatization are less marked than has been claimed in some papers and may vary between laboratories, depending on the experimental procedures used, in particular the efficiency of exclusion of O2 during

  4. Assessment of selective homing and contribution to vessel formation of cryopreserved peripherally injected bone marrow mononuclear cells following experimental myocardial damage.

    PubMed

    Ciulla, M M; Ferrero, S; Montelatici, E; Gianelli, U; Braidotti, P; Calderoni, S; Paliotti, R; Annoni, G; De Camilli, E; Busca, G; Magrini, F; Bosari, S; Lazzari, L; Rebulla, P

    2006-09-01

    In view of a potential clinical use we aimed this study to assess the selective homing to the injured myocardium and the definitive fate of peripherally injected labeled and previously cryopreserved Bone Marrow Mononuclear cells (BMMNCs). The myocardial damage (cryoinjury) was produced in 59 rats (45 treated, 14 controls). From 51 donor rats 4.4 x 10(9) BMMNCs were isolated and cryopreserved (slow-cooling protocols); the number of CD34+ and the viability of pooled cells was assessed by flow-cytometry analysis before and after cryopreservation and simulated delivery through a 23G needle. Seven days after injury, BMMNCs were thawed, labeled with PKH26 dye and peripherally injected (20 x 10(6) cells in 500 microl) in recipient rats. Two weeks after experimental injury, the heart, lungs, liver, kidneys, spleen and thymus were harvested to track transplanted cells. Except a small amount in the spleen, PKH26+ cells were found only in the infarcted myocardium of the treated animals. Typical vascular structures CD34+ were found in the infarcted areas of all animals; treated rats showed a significantly higher number of these structures if compared with untreated. Morphological ultra-structural examination of infarcted areas confirmed in treated rats the presence of early-stage PKH26+ vascular structures derived from injected BMMNCs. The estimated mean CD34+ cells loss due to the cryopreservation procedure and to the system of delivery was 0.24% and 0.1%, respectively, confirming the feasibility of the procedure. This study supports the possible therapeutic use of cryopreserved peripherally injecetd BMMNCs as a source of CD34+ independent vascular structures following myocardial damage.

  5. THE K-REGION DIHYDRODIOL OF BENZO[A]PYRENE INDUCES DNA DAMAGE AND MORPHOLOGICAL CELL TRANSFORMATION IN C3H10T1/2CL8 MOUSE EMBRYO CELLS WITHOUT THE FORMATION OF DETECTABLE STABLE COVALENT DNA ADDUCTS

    EPA Science Inventory

    The K -region dihydrodiol ofbenzo[ a ]pyrene induces DNA damage and morphological cell transformation in C3HlOTY2CL8 mouse embryo cells without the formation of detectable stable covalent DNA adducts

    Benzo[ a ]pyrene (B[ a ]P) is the most thoroughly studied polycyclic aro...

  6. THE K-REGION DIHYDRODIOL OF BENZO[A]PYRENE INDUCES DNA DAMAGE AND MORPHOLOGICAL CELL TRANSFORMATION IN C3H10T1/2CL8 MOUSE EMBRYO CELLS WITHOUT THE FORMATION OF DETECTABLE STABLE COVALENT DNA ADDUCTS

    EPA Science Inventory

    The K -region dihydrodiol ofbenzo[ a ]pyrene induces DNA damage and morphological cell transformation in C3HlOTY2CL8 mouse embryo cells without the formation of detectable stable covalent DNA adducts

    Benzo[ a ]pyrene (B[ a ]P) is the most thoroughly studied polycyclic aro...

  7. Inhibition of mTOR by Rapamycin Results in Auditory Hair Cell Damage and Decreased Spiral Ganglion Neuron Outgrowth and Neurite Formation In Vitro

    PubMed Central

    Leitmeyer, Katharina; Glutz, Andrea; Radojevic, Vesna; Setz, Cristian; Huerzeler, Nathan; Bumann, Helen; Bodmer, Daniel; Brand, Yves

    2015-01-01

    Rapamycin is an antifungal agent with immunosuppressive properties. Rapamycin inhibits the mammalian target of rapamycin (mTOR) by blocking the mTOR complex 1 (mTORC1). mTOR is an atypical serine/threonine protein kinase, which controls cell growth, cell proliferation, and cell metabolism. However, less is known about the mTOR pathway in the inner ear. First, we evaluated whether or not the two mTOR complexes (mTORC1 and mTORC2, resp.) are present in the mammalian cochlea. Next, tissue explants of 5-day-old rats were treated with increasing concentrations of rapamycin to explore the effects of rapamycin on auditory hair cells and spiral ganglion neurons. Auditory hair cell survival, spiral ganglion neuron number, length of neurites, and neuronal survival were analyzed in vitro. Our data indicates that both mTOR complexes are expressed in the mammalian cochlea. We observed that inhibition of mTOR by rapamycin results in a dose dependent damage of auditory hair cells. Moreover, spiral ganglion neurite number and length of neurites were significantly decreased in all concentrations used compared to control in a dose dependent manner. Our data indicate that the mTOR may play a role in the survival of hair cells and modulates spiral ganglion neuronal outgrowth and neurite formation. PMID:25918725

  8. Influence of stellar multiplicity on planet formation. I. Evidence of suppressed planet formation due to stellar companions within 20 au and validation of four planets from the Kepler multiple planet candidates

    SciTech Connect

    Wang, Ji; Fischer, Debra A.; Xie, Ji-Wei; Barclay, Thomas

    2014-03-01

    The planet occurrence rate for multiple stars is important in two aspects. First, almost half of stellar systems in the solar neighborhood are multiple systems. Second, the comparison of the planet occurrence rate for multiple stars to that for single stars sheds light on the influence of stellar multiplicity on planet formation and evolution. We developed a method of distinguishing planet occurrence rates for single and multiple stars. From a sample of 138 bright (K{sub P} < 13.5) Kepler multi-planet candidate systems, we compared the stellar multiplicity rate of these planet host stars to that of field stars. Using dynamical stability analyses and archival Doppler measurements, we find that the stellar multiplicity rate of planet host stars is significantly lower than field stars for semimajor axes less than 20 AU, suggesting that planet formation and evolution are suppressed by the presence of a close-in companion star at these separations. The influence of stellar multiplicity at larger separations is uncertain because of search incompleteness due to a limited Doppler observation time baseline and a lack of high-resolution imaging observation. We calculated the planet confidence for the sample of multi-planet candidates and find that the planet confidences for KOI 82.01, KOI 115.01, KOI 282.01, and KOI 1781.02 are higher than 99.7% and thus validate the planetary nature of these four planet candidates. This sample of bright Kepler multi-planet candidates with refined stellar and orbital parameters, planet confidence estimation, and nearby stellar companion identification offers a well-characterized sample for future theoretical and observational study.

  9. Alterations in platelet Ca2+ signalling in diabetic patients is due to increased formation of superoxide anions and reduced nitric oxide production.

    PubMed

    Schaeffer, G; Wascher, T C; Kostner, G M; Graier, W F

    1999-02-01

    Increased aggregation of platelets might contribute to the development of vascular complication in diabetes mellitus. In this study release of superoxide anions, intracellular Ca2+ signalling and nitric oxide formation stimulated by the receptor-dependent agonist adenosine 5 '-diphosphate (ADP) and the receptor-independent stimulus thapsigargin, were compared in platelets isolated from patients with Type II (non-insulin-dependent) diabetes mellitus and healthy control subjects. Diabetes augmented intracellular Ca2+ release and Ca2+ entry to ADP by 40 and 44% (control subjects: n = 11; diabetic: n = 6), while the median effective concentration (EC50) of ADP to initiate Ca2+ signalling was similar in both groups. The effect of thapsigargin on Ca2+ concentration was increased by 69% in diabetic patients (control subjects: n = 22; diabetic patients: n = 9). In addition, release of superoxide anions was 70% greater in diabetic patients (control subjects: n = 9; diabetic patients: n = 6). Treatment of platelets from control subjects with the superoxide anion-generating mixture xanthine oxidase and hypoxanthine or buthioninesulphoximine (BSO) mimicked the effect of diabetes on platelet Ca2+ signalling. The antioxidant glutathione normalized enhanced Ca2+ response in the diabetic group (control subjects: n = 5: diabetic patients: n = 6). Basal and thapsigargin-evoked nitric oxide synthase activity was reduced in the diabetic group by 85 and 64%, respectively (control subjects: n = 13; diabetic subjects: n = 13). The nitric oxide-donor 2-(N,N-diethylamino)-diazenolate-2-oxide sodium (DEA/NO) normalized enhanced Ca2+ signalling in platelets preincubated with xanthine oxidase and hypoxanthine (n = 12) and in those from diabetics (control subjects: n = 6; diabetic patients: n = 6). Inhibition of nitric oxide synthase by N-nitro-L-arginine (L-NA) augmented thapsigargin-induced Ca2+ signalling by 51% (n = 8). These data indicate that in diabetes platelet Ca2+ signalling might be

  10. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Spatial self-organisation of a defect generation wave and laser-induced formation of ordered and crystallographic-oriented regions of optical damage in crystals

    NASA Astrophysics Data System (ADS)

    Emel'yanov, Vladimir I.; Rogacheva, Aleksandra V.

    2004-06-01

    The spatial self-organisation of a defect generation wave (DGW) in laser-excited crystalline semiconductors and dielectrics is considered. It is shown that due to the elastic crystal anisotropy, for a Gaussian intensity distribution of exciting laser radiation, the DGW is focused along the crystallographic axes, resulting in the production of optical damage 'stars'.

  11. In Situ TEM Observations of Sn-Containing Silicon Nanowires Undergoing Reversible Pore Formation Due to Fast Lithiation/Delithiation Kinetics

    SciTech Connect

    Lu, Xiaotang; Bogart, Timothy D.; Gu, Meng; Wang, Chong M.; Korgel, Brian

    2015-09-03

    In situ transmission electron microscopy (TEM) studies were carried out to observe directly in real time the lithiation and delithiation of silicon (Si) nanowires with significant amounts of tin (Sn). The incorporation of Sn significantly enhances the lithiation rate compared to typical Si nanowires. For instance, surface diffusion is enhanced by two orders of magnitude and the bulk lithiation rate by one order of magnitude, resulting in a sequential surface-then-core lithiation mechanism. Pore formation was observed in the nanowires during delithiation, most likely as a result of the fast delithiation kinetics of the nanowires. Pore formation was reversible and the pores disappeared during subsequent lithiation. When an amorphous Si shell was applied to the nanowires, pore formation was not observed during the in situ TEM experimences. Ex situ TEM analysis of Sn-containing Si nanowires cycled in coin cell batteries also showed that the application of an a-Si shell significantly retards pore formation in these nanowires.

  12. Effect of Low Temperature on Fatigue Crack Formation and Microstructure-Scale Growth from Corrosion Damage in Al-Zn-Mg-Cu

    NASA Astrophysics Data System (ADS)

    Burns, James T.; Gangloff, Richard P.

    2013-05-01

    The strong effect of cold temperature on the fatigue resistance of 7075-T651 is established. As temperature decreases from 296 K to 183 K (23 °C to -90 °C), the formation life for cracking about pit and EXCO corrosion perimeters increases, microstructure scale crack growth rates decrease in the range from 20 to 500 μm beyond the corrosion topography, and long crack growth rates similarly decline. Fatigue crack surface features correlate with reduced hydrogen embrittlement with decreasing temperature fed by localized H produced during precorrosion for pit and EXCO-proximate cracks, as well as by crack tip H produced by water vapor reaction during stressing for all crack sizes. The importance of the former H source increases with decreasing temperature for cracks sized below 200 μm. Decreasing temperature to 223 K (-50 °C) eliminates the contribution of environmental H through interaction of reduced water vapor pressure in equilibrium with ice and reduced H diffusion. The Knudsen flow model and exposure parameter, P_{{{{H}}2 {{O}}}}/f , enables improved modeling of temperature dependent crack propagation, but does not fully describe low temperature fatigue behavior due to possible rate limitation by H diffusion. Further decreases in MSC da/dN to 183 K (-90 °C) are related to reduced mobility of the corrosion-precharged H which may associate with vacancies from dissolution. Crack formation, and growth rates correlate with either elastic stress intensity range or cyclic crack tip opening displacement, and are available to predict corrosion effects on airframe fatigue for the important low temperature regime.

  13. The non-major histocompatibility complex quantitative trait locus Cia10 contains a major arthritis gene and regulates disease severity, pannus formation, and joint damage.

    PubMed

    Brenner, Max; Meng, Hsiang-Chi; Yarlett, Nuriza C; Griffiths, Marie M; Remmers, Elaine F; Wilder, Ronald L; Gulko, Pércio S

    2005-01-01

    To construct rats congenic for the chromosome 2 arthritis-regulatory quantitative trait locus Cia10, originally identified in a (DA x ACI)F(2) intercross rat strain that had been assessed for collagen-induced arthritis (CIA), and to determine the effect of this congenic interval on arthritis severity, joint histologic structure, and cytokine transcription in rats with pristane-induced arthritis (PIA). A 52.6-MB interval derived from the ACI (CIA- and PIA-resistant) strain and containing the Cia10 interval was introgressed into the DA (arthritis-susceptible) background through genotype-guided congenic breeding. Homozygous male and female DA.ACI(Cia10) congenic rats were studied for their susceptibility to and severity of PIA, and were compared with same-sex DA rats. Histologic analyses were done on hind paws collected on day 32 following the pristane injection. Levels of interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNFalpha) messenger RNA (mRNA) were measured with real-time polymerase chain reaction on synovial tissues from day-32 ankles. Both male and female DA.ACI(Cia10) congenic rats developed a significantly milder form of arthritis, with a 95% and 92% reduction in the arthritis severity index compared with DA male and female controls, respectively (males P < or = 0.001 and females P = 0.003). DA.ACI(Cia10) congenic rat synovial tissue was more likely to preserve its normal histologic architecture, including minimal to no cartilage and bone erosions, synovial hyperplasia, and pannus formation, and reduced numbers of vessels (angiogenesis), when compared with DA synovial tissue. There was a 2.7- and 2.4-fold reduction in the amount of IL-1beta and TNFalpha mRNA, respectively, in the synovial tissue of DA.ACI(Cia10) congenic rats compared with DA rats. Sequencing analyses of complementary DNA for the Cia10-predicted candidate gene Ptpn8, the rat homolog of the rheumatoid arthritis (RA)-susceptibility gene PTPN22, revealed no polymorphisms between

  14. Effect of reaction pH and CuSO4 addition on the formation of catechinone due to oxidation of (+)-catechin.

    PubMed

    Matsubara, T; Wataoka, I; Urakawa, H; Yasunaga, H

    2013-08-01

    A novel hair dyeing technique being milder and safer for a human body is desired. The oxidation product of (+)-catechin, catechinone, was invented as a safer dyestuff for hair colouring under such the situation. The preparation of catechinone by a chemical oxidation is a practical way and the objective of the study is clarify the effect of the solution pH and in the presence or absence of Cu(2+) on the formation rate and yield of catechinone in order to improve the efficiency of the dye formation. The catechinone formation was monitored by ultraviolet-visible spectroscopy. Catechinone was prepared chemically from (+)-catechin in aqueous solution with O2 gas introduced over a pH range of 7.1-11.7. The rate and amount of the dye formation increase with increasing pH. Dissociation of the hydroxyl group of the catechol part of (+)-catechin is significant for the oxidation of (+)-catechin and promotes the dye production. This is because the deprotonated (+)-catechin has a higher reactivity with O2 . The production of catechinone is accelerated by the addition of CuSO4 and the production rate reaches the maximum at pH = 8.8. (+)-Catechin - Cu(2+) complexes are formed and the formation promotes the oxidation of the catechol part of (+)-catechin at pH ≤ 8.8. On the other hand, the complex becomes too stable to proceed for the oxidation reaction at pH > 8.8.

  15. ATM mediates interdependent activation of p53 and ERK through formation of a ternary complex with p-p53 and p-ERK in response to DNA damage.

    PubMed

    Heo, Jee-In; Oh, Soo-Jin; Kho, Yoon-Jung; Kim, Jeong-Hyeon; Kang, Hong-Joon; Park, Seong-Hoon; Kim, Hyun-Seok; Shin, Jong-Yeon; Kim, Min-Ju; Kim, Minju; Kim, Sung Chan; Park, Jae-Bong; Kim, Jaebong; Lee, Jae-Yong

    2012-08-01

    DNA damage in eukaryotic cells induces signaling pathways mediated by the ATM, p53 and ERK proteins, but the interactions between these pathways are not completely known. To address this issue, we performed a time course analysis in human embryonic fibroblast cells treated with DNA-damaging agents. DNA damage induced the phosphorylation of p53 at Ser 15 (p-p53) and the phosphorylation of ERK (p-ERK). Inhibition of p53 by a dominant negative mutant or in p53(-/-) fibroblast cells abolished ERK phosphorylation. ERK inhibitor prevented p53 phosphorylation, indicating that phosphorylations of p53 and p-ERK are interdependent each other. A time course analysis showed that ATM interacted with p-p53 and p-ERK in early time (0.5 h) and interaction between ATM-bound p-p53 and p-ERK or ATM-bound p-ERK and p-p53 occurred in late time (3 h) of DNA damage. These results indicate that ATM mediates interdependent activation of p53 and ERK through formation of a ternary complex between p-p53 and p-ERK in response to DNA damage to cause growth arrest.

  16. War Damage Assessment

    NASA Technical Reports Server (NTRS)

    1994-01-01

    During and after the Persian Gulf war, hundreds of "oil lakes" were created in Kuwait by oil released from damaged wells. The lakes are a hazard to the Kuwait atmosphere, soil and ground water and must be carefully monitored. Boston University Center for Remote Sensing, assisted by other organizations, has accurately mapped the lakes using Landsat and Spot imagery. The war damage included the formation of over 300 oil lakes, oil pollution and sand dune movement. Total damage area is over 5,400 square kilometers - 30 percent of Kuwait's total surface area.

  17. EFFECTS OF LASER RADIATION ON MATTER: Efficient surface-erosion plasma formation in air due to the action of pulse-periodic laser radiation

    NASA Astrophysics Data System (ADS)

    Min'ko, L. Ya; Chumakou, A. N.; Bosak, N. A.

    1990-11-01

    A study was made of the interaction of a series of periodic laser (λ = 1.06 μm) pulses with a number of materials (aluminum, copper, graphite, ebonite) in air at laser radiation power densities q = 107-109 W/cm2 and repetition frequencies f<=50 kHz. The radiation was concentrated in spots of ~ 10 - 2 cm2 area. Efficient formation of plasma as a result of laser erosion (q > 2 × 108 W/cm2, f>=5 kHz) was observed. A screening layer of an air plasma created by the first pulse of the series was expelled from the interaction zone and this was followed by erosion plasma formation under conditions of slight screening of the target during the action of the subsequent laser pulses.

  18. Pseudomonas aeruginosa Exhibits Deficient Biofilm Formation in the Absence of Class II and III Ribonucleotide Reductases Due to Hindered Anaerobic Growth

    PubMed Central

    Crespo, Anna; Pedraz, Lucas; Astola, Josep; Torrents, Eduard

    2016-01-01

    Chronic lung infections by the ubiquitous and extremely adaptable opportunistic pathogen Pseudomonas aeruginosa correlate with the formation of a biofilm, where bacteria grow in association with an extracellular matrix and display a wide range of changes in gene expression and metabolism. This leads to increased resistance to physical stress and antibiotic therapies, while enhancing cell-to-cell communication. Oxygen diffusion through the complex biofilm structure generates an oxygen concentration gradient, leading to the appearance of anaerobic microenvironments. Ribonucleotide reductases (RNRs) are a family of highly sophisticated enzymes responsible for the synthesis of the deoxyribonucleotides, and they constitute the only de novo pathway for the formation of the building blocks needed for DNA synthesis and repair. P. aeruginosa is one of the few bacteria encoding all three known RNR classes (Ia, II, and III). Class Ia RNRs are oxygen dependent, class II are oxygen independent, and class III are oxygen sensitive. A tight control of RNR activity is essential for anaerobic growth and therefore for biofilm development. In this work we explored the role of the different RNR classes in biofilm formation under aerobic and anaerobic initial conditions and using static and continuous-flow biofilm models. We demonstrated the importance of class II and III RNR for proper cell division in biofilm development and maturation. We also determined that these classes are transcriptionally induced during biofilm formation and under anaerobic conditions. The molecular mechanism of their anaerobic regulation was also studied, finding that the Anr/Dnr system is responsible for class II RNR induction. These data can be integrated with previous knowledge about biofilms in a model where these structures are understood as a set of layers determined by oxygen concentration and contain cells with different RNR expression profiles, bringing us a step closer to the understanding of this

  19. The Role of Carbides in Formation of Surface Layer on Steel X153CrMoV12 Due to Low-Pressure Nitriding (Vacuum Nitriding)

    NASA Astrophysics Data System (ADS)

    Januszewicz, B.; Wołowiec, E.; Kula, P.

    2015-05-01

    The mechanism of formation of surface layer on steel X153CrMoV12 in the process of vacuum nitriding (low-pressure nitriding) in a universal vacuum furnace in an atmosphere of dissociated ammonia at a pressure of 30 × 102 Pa (30 mbar) is studied by the methods of light microscopy and measurement of microhardness. The chemical composition of the nitrided layers is determined.

  20. Batch tests on mineral deposit formation due to co-mingling of leachates derived from municipal solid wastes and waste-to-energy combustion residues.

    PubMed

    Cardoso, Antonio J; Levine, Audrey D

    2009-02-01

    Deposit formation in leachate collection systems can be problematic for landfill operations. Deposits from municipal solid waste (MSW) derived leachates are impacted by microbial activity and biofilm development, whereas leachates generated from co-disposal of MSW with combustion residues (CR) from waste-to-energy (WTE) facilities and other mineral-rich waste materials are more prone to forming dense mineral deposits dominated by calcium carbonate. In this study, leachates from laboratory lysimeters containing either WTE-CR or shredded MSW were mixed at different volumetric ratios. The mixed leachates were incubated for 5 weeks in batch tests to evaluate the potential for formation of precipitates. Although mineral precipitates have been reported to form in landfills with no co-disposal practices, in this study mineral precipitates did not form in either the WTE-CR derived leachate or the MSW derived leachate, but formed in all leachate mixtures. Mineral precipitates consisted of calcium carbonate particles, with the highest yield from a 1:1