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Sample records for circumferential odscc degradation

  1. Status of the steam generator tube circumferential ODSCC degradation experienced at the Doel 4 plant

    Energy Technology Data Exchange (ETDEWEB)

    Roussel, G. [AIB-Vincotte Nuclear, Brussels (Belgium)

    1997-02-01

    Since the 1991 outage, the Doel Unit 4 nuclear power plant is known to be affected by circumferential outside diameter intergranular stress corrosion cracking at the hot leg tube expansion transition. Extensive non destructive examination inspections have shown the number of tubes affected by this problem as well as the size of the cracks to have been increasing for the three cycles up to 1993. As a result of the high percentage of tubes found non acceptable for continued service after the 1993 in-service inspection, about 1,700 mechanical sleeves were installed in the steam generators. During the 1994 outage, all the tubes sleeved during the 1993 outage were considered as potentially cracked to some extent at the upper hydraulic transition and were therefore not acceptable for continued service. They were subsequently repaired by laser welding. Furthermore all the tubes not sleeved during the 1993 outage were considered as not acceptable for continued service and were repaired by installing laser welded sleeves. During the 1995 outage, some unexpected degradation phenomena were evidenced in the sleeved tubes. This paper summarizes the status of the circumferential ODSCC experienced in the SG tubes of the Doel 4 plant as well as the other connected degradation phenomena.

  2. A REVIEW ON THE ODSCC OF STEAM GENERATOR TUBES IN KOREAN NPPS

    Directory of Open Access Journals (Sweden)

    HANSUB CHUNG

    2013-08-01

    Full Text Available The ODSCC detected in the TSP position of Ulchin 3&4 SGs are typical ODSCC of Alloy 600MA tubes. The causative chemical environment is formed by concentration of impurities inside the occluded region formed by the tube surface, egg crate strips, and sludge deposit there. Most cracks are detected at or near the line contacts between the tube surface and the egg crate strips. The region of dense crack population, as defined as between 4th and 9th TSPs, and near the center of hot leg hemisphere plane, coincided well with the region of preferential sludge deposition as defined by thermal hydraulics calculation using SGAP computer code. The cracks developed homogeneously in a wide range of SGs, so that the number of cracks detected each outage increased very rapidly since the first detection in the 8th refueling outage. The root cause assessment focused on investigation of the difference in microstructure and manufacturing residual stress in order to reveal the cause of different susceptibilities to ODSCC among identical six units. The manufacturing residual stress as measured by XRD on OD surface and by split tube method indicated that the high residual stress of Alloy 600MA tube played a critical role in developing ODSCC. The level of residual stress showed substantial variations among the six units depending on details of straightening and OD grinding processes. Youngwang 3&4 tubes are less susceptible to ODSCC than U3 and U4 tubes because semi-continuous coarse chromium carbides are formed along the grain boundary of Y3&4 tubes, while there are finer less continuous chromium carbides in U3 and U4. The different carbide morphology is caused by the difference in cooling rate after mill anneal. There is a possibility that high chromium content in the Y3&4 tubes, still within the allowable range of Alloy 600, has made some contribution to the improved resistance to ODSCC. It is anticipated that ODSCC in Y5&6 SGs will be retarded more considerably

  3. Assessment of the leak tightness integrity of the steam generator tubes affected by ODSCC at the tube support plates

    Energy Technology Data Exchange (ETDEWEB)

    Cuvelliez, Ch.; Roussel, G. [AIB-Vincotte Nuclear, Brussels (Belgium)

    1997-02-01

    An EPRI report gives a method for predicting a conservative value of the total primary-to-secondary leak rate which may occur during, a postulated steam generator depressurization accident such as a Main Steam Line Break (MSLB) in a steam generator with axial through-wall ODSCC at the TSP intersections. The Belgian utility defined an alternative method deviating somewhat from the EPRI method. When reviewing this proposed method, the Belgian safety authorities performed some calculations to investigate its conservatism. This led them to recommend some modifications to the EPRI method which should reduce its undue conservatism while maintaining the objective of conservatism in the offsite dose calculations.

  4. Structural and leakage integrity of tubes affected by circumferential cracking

    Energy Technology Data Exchange (ETDEWEB)

    Hernalsteen, P. [TRACTEBEL, Brussels (Belgium)

    1997-02-01

    In this paper the author deals with the notion that circumferential cracks are generally considered unacceptable. He argues for the need to differentiate two facets of such cracks: the issue of the size and growth rate of a crack; and the issue of the structural strength and leakage potential of the tube in the presence of the crack. In this paper the author tries to show that the second point is not a major concern for such cracks. The paper presents data on the structural strength or burst pressure characteristics of steam generator tubes derived from models and data bases of experimental work. He also presents a leak rate model, and compares the performance of circumferential and axial cracks as far as burst strength and leak rate. The final conclusion is that subject to improvement in NDE capabilities (sizing, detection, growth), that Steam Generator Defect Specific Management can be used to allow circumferentially degraded tubes to remain in service.

  5. 49 CFR 178.345-7 - Circumferential reinforcements.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Circumferential reinforcements. 178.345-7 Section... reinforcements. (a) A cargo tank with a shell thickness of less than 3/8 inch must be circumferentially... tank heads. (1) Circumferential reinforcement must be located so that the thickness and...

  6. Guided Circumferential Waves in Layered Poroelastic Cylinders

    Directory of Open Access Journals (Sweden)

    Shah S.A.

    2016-12-01

    Full Text Available The present paper investigates the propagation of time harmonic circumferential waves in a two-dimensional hollow poroelastic cylinder with an inner shaft (shaft-bearing assembly. The hollow poroelastic cylinder and inner shaft are assumed to be infinite in axial direction. The outer surface of the cylinder is stress free and at the interface, between the inner shaft and the outer cylinder, it is assumed to be free sliding and the interfacial shear stresses are zero, also the normal stress and radial displacements are continuous. The frequency equation of guided circumferential waves for a permeable and an impermeable surface is obtained. When the angular wave number vanish the frequency equation of guided circumferential waves for a permeable and an impermeable surface degenerates and the dilatational and shear waves are uncoupled. Shear waves are independent of the nature of surface. The frequency equation of a permeable and an impermeable surface for bore-piston assembly is obtained as a particular case of the model under consideration when the outer radius of the hollow poroelastic cylinder tends to infinity. Results of previous studies are obtained as a particular case of the present study. Nondimensional frequency as a function of wave number is presented graphically for two types of models and discussed. Numerical results show that, in general, the first modes are linear for permeable and impermeable surfaces and the frequency of a permeable surface is more than that of an impermeable surface.

  7. French steam generator tubes: an overview of degradations

    Energy Technology Data Exchange (ETDEWEB)

    Buisine, D.; Bouvier, O. de; Rupa, N.; Thebault, Y.; Barbe, V. [EDF-CEIDRE Nuclear Engineering Division (France); Pitner, P. [EDF-UNIE Generation Nuclear Operation Division (France)

    2011-07-01

    The various damages (corrosion, fatigue cracks, wear, ...) observed on steam generator (SG) tubes are presented here as well as the techniques used to characterize these damages. The SG are equipped with tubes of 3 materials: 600 MA, 600 TT and 690 TT. Concerning PWSCC of 600 MA and 600 TT tubes, beyond the damages usually observed (corrosion in expansion transition zone and in 600 MA tubes small radius U-bend zone), a new event is to be noted: the phenomenon of denting (presumably induced by the deposit of sludge on the tubesheet) has induced circumferential cracking of the tube expansion transition zone. Concerning ODSCC of 600 MA tubes, beyond the classically observed damages (IGA and IGSCC in expansion transition zone and in TSP crevice), a new event is to be noted: the occurrence of circumferential cracks in tube- TSP crevice. Concerning fatigue cracking, two events have to be noted at upper TSP level in Cruas 1 and Cruas 4 units and in Fessenheim 2 unit. The first (Cruas) was due to the blockage in the broached hole tube support plate which can create critical velocity ratios for some tubes and the second (Fessenheim) to high-cycle fatigue. Concerning wear damage, beyond what is usually observed in the U-bend zone facing the anti-vibration bars (AVB), a new event is to be noted: a wear at TSP level is observed on SG equipped with an economizer, the wear indications being located at TSP 7 and 8 level, on outer tubes close to the central lane. The number of tubes plugged for ODSCC has declined due to the progressive replacement of SG with Alloy 600 MA tubing. Starting in 2004, the increasing plugging of 690 tubing is mainly due to AVB wear. Since 2006, extensive preventive plugging campaigns for tubes at risk of high-cycle fatigue at the upper support plate are performed. Risk of high-cycle fatigue has consequently become the dominant mechanism inducing plugging. PWSCC is the second dominant mechanism which affects 600 MA and 600 TT tube bundles: extensive

  8. Inspection of circumferential IGA/SCC in Bruce Unit 4 SGs

    Energy Technology Data Exchange (ETDEWEB)

    Fluit, S.; Myderwyk, H.; King, P. [Babcock and Wilcox Canada Limited, Cambridge, Ontario (Canada); Durance, D.; Sedman, K. [Bruce Power, Tiverton, Ontario (Canada)

    2008-07-01

    Circumferential IGA/SCC has been detected in the roll-transition zone of tubes in Bruce A SGs for over a decade, but recently became more pronounced in Unit 4 BO4 in 2006 and the spring of 2007. A number of ET probes have been developed to detect and characterize this degradation, including C-3/8, +Point and X-Probe. Comparisons of the inspection results from these probes and metallurgical results from removed tubes have provided insight into the strengths and limitations of each probe and how the probes can complement each other. This paper will discuss the evolution of the ET inspection approach for circumferential IGA/SCC and how the results have been used in recent FFS assessments in the Bruce Unit 4 SGs. (author)

  9. CIRCUMFERENTIAL MFL IN-LINE INSPECTION FOR CRACKS IN PIPELINES

    Energy Technology Data Exchange (ETDEWEB)

    J.B. Nestleroth

    2003-06-01

    Circumferential MFL is a new implementation of a widely used technology that has potential to provide improved detection and quantification of axially oriented defects such as cracks, seam weld defects, mechanical damage, and groove corrosion. This implementation works by orienting the magnetic field around the pipe rather that along the axis. By orienting the magnetic field around the pipe (the circumferential direction), the axial defects that were magnetically transparent can disrupt more of the magnetic field and can be more easily detected. Initial implementations of circumferential MFL have found that flux leakage from cracks at the interior of the pipe is small, and the signals from cracks are difficult to detect. The objective of this project is to improve detection of cracks by changing the implementation along with using data from overlapping and complementary inspection techniques. Two technology enhancements were investigated: Combining high- and low-magnetization technology for stress detection; and Combining axial and circumferential MFL methods. Although a method combining high- and low-magnetization technology showed promise for characterizing gouges cause by third party excavation equipment, its commercial development was not successful for two reasons. First, the stress diminishes the crack signal, while the opening of the crack increases the signal. The stress-induced changes in flux leakage around cracks were small and any critical information on the severity of cracks and crack-like defects is difficult to distinguish from changes caused by the crack opening and other inspection variables. Second, it is difficult to magnetize pipe material in the circumferential direction. A relatively low, non-uniform magnetization level produced by the circumferential magnetizer makes detection of changes due to stress extremely difficult. This project also examined combining axial and circumferential MFL to improve crack detection and distinguish cracks for

  10. Circumferential gap propagation in an anisotropic elastic bacterial sacculus

    CERN Document Server

    Taneja, Swadhin; Rutenberg, Andrew D

    2013-01-01

    We have modelled stress concentration around small gaps in anisotropic elastic sheets, corresponding to the peptidoglycan sacculus of bacterial cells, under loading corresponding to the effects of turgor pressure in rod-shaped bacteria. We find that under normal conditions the stress concentration is insufficient to mechanically rupture bacteria, even for gaps up to a micron in length. We then explored the effects of stress-dependent smart-autolysins, as hypothesised by Arthur L Koch [Advances in Microbial Physiology 24, 301 (1983); Research in Microbiology 141, 529 (1990)]. We show that the measured anisotropic elasticity of the PG sacculus can lead to stable circumferential propagation of small gaps in the sacculus. This is consistent with the recent observation of circumferential propagation of PG-associated MreB patches in rod-shaped bacteria. We also find a bistable regime of both circumferential and axial gap propagation, which agrees with behavior reported in cytoskeletal mutants of B. subtilis. We con...

  11. GUIDED CIRCUMFERENTIAL WAVES IN DOUBLE-WALLED CARBON NANOTUBES

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A model of guided circumferential waves propagating in double-walled carbon nanotubes is built by the theory of wave propagation in continuum mechanics, while the van der Waals force between the inner and outer nanotube has been taken into account in the model. The dispersion curves of the guided circumferential wave propagation are studied, and some dispersion characteristics are illustrated by comparing with those of single-walled carbon nanotubes. It is found that in double-walled carbon nanotubes, the guided circumferential waves will propagate in more dispersive ways. More interactions between neighboring wave modes may take place. In particular, it has been found that a couple of wave modes may disappear at a certain frequency and that, while a couple of wave modes disappear, another new couple of wave modes are excited at the same wave number.

  12. Circumferential nonlocal effect on the buckling and vibration of nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Cheng Yuan, E-mail: cywang@ujs.edu.cn; Li, Xiao Hu; Luo, Ying

    2016-04-01

    The nonlocal beam theories are widely used to study the mechanics of cylindrical nanotubes (NTs). The one-dimensional models however are unable to account for the nonlocal effect in the circumferential direction, which may substantially affect the applicability of the nonlocal beam models. To address the issue this letter examines the circumferential nonlocal effect (CNE) on the buckling and vibration of the NTs. Here the CNE is characterized by the difference between the nonlocal beam model considering the axial nonlocal effect only and the nonlocal shell model with both axial and circumferential nonlocal effects. The aspect ratio and radius-dependence of the CNE are calculated for the singlewall carbon NTs selected as a typical example. The results show that the CNE is substantial for the buckling and vibration of the NTs with small radius (e.g., <1 nm) and aspect ratio (e.g., <15). It however decreases with the rising radius and the aspect ratio, and turns out to be small for relatively wide and long NTs. The nonlocal beam theories thus may overestimate the buckling load and vibration frequency for the thin and short NTs. - Highlights: • First revealed the substantial circumferential nonlocal effect (CNE) on nanotube buckling. • Achieved radius/aspect ratio-dependence of CNE on nanotube buckling and vibration. • Located the range of applicability of the nonlocal beam theory without CNE.

  13. A Critical Appraisal of Circumferential Resection Margins in Esophageal Carcinoma

    NARCIS (Netherlands)

    Pultrum, Bareld B.; Honing, Judith; Smit, Justin K.; van Dullemen, Hendrik M.; van Dam, Gooitzen M.; Groen, Henk; Hollema, Harry; Plukker, John Th. M.

    2010-01-01

    In esophageal cancer, circumferential resection margins (CRMs) are considered to be of relevant prognostic value, but a reliable definition of tumor-free CRM is still unclear. The aim of this study was to appraise the clinical prognostic value of microscopic CRM involvement and to determine the opti

  14. Recent evaluations of crack-opening-area in circumferentially cracked pipes

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, S.; Brust, F.; Ghadiali, N.; Wilkowski, G.; Miura, N.

    1997-04-01

    Leak-before-break (LBB) analyses for circumferentially cracked pipes are currently being conducted in the nuclear industry to justify elimination of pipe whip restraints and jet shields which are present because of the expected dynamic effects from pipe rupture. The application of the LBB methodology frequently requires calculation of leak rates. The leak rates depend on the crack-opening area of the through-wall crack in the pipe. In addition to LBB analyses which assume a hypothetical flaw size, there is also interest in the integrity of actual leaking cracks corresponding to current leakage detection requirements in NRC Regulatory Guide 1.45, or for assessing temporary repair of Class 2 and 3 pipes that have leaks as are being evaluated in ASME Section XI. The objectives of this study were to review, evaluate, and refine current predictive models for performing crack-opening-area analyses of circumferentially cracked pipes. The results from twenty-five full-scale pipe fracture experiments, conducted in the Degraded Piping Program, the International Piping Integrity Research Group Program, and the Short Cracks in Piping and Piping Welds Program, were used to verify the analytical models. Standard statistical analyses were performed to assess used to verify the analytical models. Standard statistical analyses were performed to assess quantitatively the accuracy of the predictive models. The evaluation also involved finite element analyses for determining the crack-opening profile often needed to perform leak-rate calculations.

  15. Circumferential evaluation of the neointima by optical coherence tomography after ABSORB bioresorbable vascular scaffold implantation

    DEFF Research Database (Denmark)

    Brugaletta, Salvatore; Radu, Maria D; Garcia-Garcia, Hector M

    2012-01-01

    To quantify the circumferential healing process at 6 and 12 months following scaffold implantation.......To quantify the circumferential healing process at 6 and 12 months following scaffold implantation....

  16. Circumferential buckling instability of a growing cylindrical tube

    KAUST Repository

    Moulton, D.E.

    2011-03-01

    A cylindrical elastic tube under uniform radial external pressure will buckle circumferentially to a non-circular cross-section at a critical pressure. The buckling represents an instability of the inner or outer edge of the tube. This is a common phenomenon in biological tissues, where it is referred to as mucosal folding. Here, we investigate this buckling instability in a growing elastic tube. A change in thickness due to growth can have a dramatic impact on circumferential buckling, both in the critical pressure and the buckling pattern. We consider both single- and bi-layer tubes and multiple boundary conditions. We highlight the competition between geometric effects, i.e. the change in tube dimensions, and mechanical effects, i.e. the effect of residual stress, due to differential growth. This competition can lead to non-intuitive results, such as a tube growing to be thinner and yet buckle at a higher pressure. © 2011 Elsevier Ltd. All rights reserved.

  17. Thermal shock in a circumferentially cracked hollow cylinder with cladding

    Science.gov (United States)

    Nied, H. F.

    1984-01-01

    An theoretical analysis is presented which demonstrates the effect of cladding on the thermal resistance of a circumferentially cracked hollow cylinder. The cladding is assumed to be bonded to the inner wall of the hollow cylinder. The axisymmetric circumferential crack may be either embedded in the cylinder wall or may be an edge crack which passes through the clad and opens into the inner wall of the hollow cylinder. The problem is formulated mathematically and a solution is found which is in the form of a single integral equation. The integral equation is solved numerically and yields estimates of transient temperature distributions, thermal stresses in the uncracked cylinder, and stress intensity factors as a function of time for various cladding thickness to cylinder wall thickness ratios. It is shown that yielding of the clad under certain conditions can result in a reduction in the magnitude of the stress intensity factor for the crack tip in the elastic base material.

  18. Circumferential fusion improves outcome in comparison with instrumented posterolateral fusion

    DEFF Research Database (Denmark)

    Videbaek, Tina S; Christensen, Finn B; Soegaard, Rikke;

    2006-01-01

    with respect to all four DPQ categories: daily activities, work/leisure, anxiety/depression, and social interest. The Oswestry Disability Index supported these results (P physical health (P ...STUDY DESIGN: Prospective randomized clinical study with a 5- to 9-year follow-up period. OBJECTIVE: The aim of the present study was to analyze the long-term outcome with respect to functional disability, pain, and general health of patients treated by means of circumferential lumbar fusion...... fusion (titanium Cotrel-Dubousset) or circumferential lumbar fusion (instrumented posterolateral fusion with anterior intervertebral support by a Brantigan cage). The primary outcome measure was the Dallas Pain Questionnaire (DPQ). The secondary outcome measures were the Oswestry Disability Index, the SF...

  19. Detection of a longitudinal defect in a pipe based on guided circumferential waves techniques

    Institute of Scientific and Technical Information of China (English)

    LI Longtao; HE Cunfu; WU Bin

    2005-01-01

    Based on elasticity theory, the multi-modes and disperse characteristics of guided circumferential waves in a pipe were investigated theoretically and experimentally, the disperse curves of guided circumferential waves were gotten by numerical calculations. The relationships between the angle of beam transducer, frequency and guided circumferential modes were analyzed by our guided wave experiment system. Then single guided circumferential mode was excited in the pipe (O.D 88.8 mm, I.D 80.8 mm). An artificial longitudinal defect (25 × 1 × 0.7 mm)on the surface of the pipe was detected by use of the single guided circumferential wave. The results show that single guided circumferential mode can be excited in the pipe by choosing special frequency and special angle beam transducer, similar to the excitation of Lamb wave in a plate, and it can be used to find the longitudinal defect on a pipe surface.

  20. Estimation of circumferential fiber shortening velocity by echocardiography.

    Science.gov (United States)

    Ruschhaupt, D G; Sodt, P C; Hutcheon, N A; Arcilla, R A

    1983-07-01

    The M-mode and two-dimensional echocardiograms of 40 young patients were analyzed to compare the mean circumferential fiber shortening velocity (Vcf) of the left ventricle calculated separately by two methods. The mean circumferential fiber shortening velocity was derived from the M-mode echocardiogram as minor axis shortening/ejection time and derived from the two-dimensional echocardiogram as actual circumference change/ejection time. With computer assistance, circumference was determined from the short-axis two-dimensional echocardiographic images during end-diastole and end-systole. Good correlations were obtained between the left ventricular diameter derived by M-mode echocardiography and the vertical axis during end-diastole (r = 0.79) and end-systole (r = 0.88) derived by two-dimensional echocardiography. Likewise, high correlations were noted between diameter and circumference in end-diastole (r = 0.89) and end-systole (r = 0.88). However, comparison of Vcf obtained by M-mode echocardiography with that obtained by two-dimensional echocardiography showed only fair correlation (r = 0.68). Moreover, the diameter/circumference ratio determined in end-diastole and end-systole differed significantly (p less than 0.001), possibly owing to the change in geometry of the ventricular sector image during systole. Although Vcf derived by M-mode echocardiography is a useful index of left ventricular performance, it does not truly reflect the circumference change during systole.

  1. DETERMINATION OF EFFICIENCY OF THE CIRCUMFERENTIAL DRAINAGE SYSTEM

    Directory of Open Access Journals (Sweden)

    Maciej Kroll

    2015-11-01

    Full Text Available One of the potential alternatives to improve the stability coefficient for an embankment structure is to flatten the filtration curve. As a result, we obtain lower body forces triggering the potential landslide and more advantageous soil strength parameters, which counteract landslide movements. In the case of waste dumps lowering the phreatic surface of waters is achieved thanks to the construction of auxiliary drainage systems, meeting the guidelines for their safe operation. The aim of this paper is to indicate a method facilitating the determination of the actual position of the phreatic surface within the deposited sediments and the assessment of efficiency of the circumferential drainage system in the waste dump. It was decided in this study to apply cone penetration test CPTU. The CPTU made it possible to measure dissipation of excess water pressure in pores identifying drainage conditions, which were compared with the results of piezometric measurements. The results of these tests made it possible to monitor changes in the position of the depression curve of supernatant waters in dams and to determine the efficiency of the circumferential drainage system.

  2. Characterization of mechanical and geometrical properties of a tube with axial and circumferential guided waves.

    Science.gov (United States)

    Yeh, Cheng-Hung; Yang, Che-Hua

    2011-05-01

    Guided waves propagating in cylindrical tubes are frequently applied for the characterization of material or geometrical properties of tubes. In a tube, guided waves can propagate in the axial direction and called axial guided waves, or in the circumferential direction called circumferential guided waves. Dispersion spectra for the axial and circumferential guided waves share some common behaviors and however exhibit some particular behaviors of their own. This study provides an investigation with theoretical modeling, experimental measurements, and a simplex-based inversion procedure to explore the similarity and difference between the axial guided waves and circumferential guided waves, aiming at providing useful information while axial and circumferential guided waves are applied in the area of material characterization. The sensitivity to the radius curvature for the circumferential guided waves dispersion spectra is a major point that makes circumferential guided waves different from axial guided waves. For the purpose of material characterization, both axial and circumferential guided waves are able to extract an elastic moduli and wall-thickness information from the dispersion spectra, however, radius information can only be extracted from the circumferential guided waves spectra.

  3. Low-frequency circumferential magnetization curves in magnetostrictive amorphous wires

    Energy Technology Data Exchange (ETDEWEB)

    Olivera, J. [Departamento de Fisica, Universidad de Oviedo, C/Calvo Sotelo s/n, 33007 Oviedo (Spain); Sanchez, M.L. [Departamento de Fisica, Universidad de Oviedo, C/Calvo Sotelo s/n, 33007 Oviedo (Spain); Prida, V.M. [Departamento de Fisica, Universidad de Oviedo, C/Calvo Sotelo s/n, 33007 Oviedo (Spain); Perez, M.J. [Departamento de Fisica, Universidad de Oviedo, C/Calvo Sotelo s/n, 33007 Oviedo (Spain); Santos, J.D. [Departamento de Fisica, Universidad de Oviedo, C/Calvo Sotelo s/n, 33007 Oviedo (Spain); Gorria, P. [Departamento de Fisica, Universidad de Oviedo, C/Calvo Sotelo s/n, 33007 Oviedo (Spain); Hernando, B. [Departamento de Fisica, Universidad de Oviedo, C/Calvo Sotelo s/n, 33007 Oviedo (Spain)]. E-mail: grande@pinon.ccu.uniovi.es; Sanchez Ll, J.L. [Laboratorio de Magnetismo, Facultad de Fisica-IMRE, Universidad de La Habana, La Habana 10400 (Cuba)

    2005-07-15

    Circumferential magnetization curves have been derived from the imaginary component of the impedance response in an Fe{sub 73.5}Si{sub 13.5}B{sub 9}Cu{sub 1}Nb{sub 3} amorphous wire. Measurements were performed at 1 kHz driving frequency, and 0.05- 20 mA{sub rms} current amplitude range. Axial DC fields from 0 to 100 Oe have been simultaneously applied in order to detect the magnetoinductive effect. The circular magnetization curves are compared with quasi-static longitudinal magnetization ones, and the results are analyzed on the basis of the core-shell model for a wire with positive magnetostriction.

  4. Transverse shear effect in a circumferentially cracked cylindrical shell

    Science.gov (United States)

    Delale, F.; Erdogan, F.

    1979-01-01

    The objectives of the paper are to solve the problem of a circumferentially-cracked cylindrical shell by taking into account the effect of transverse shear, and to obtain the stress intensity factors for the bending moment as well as the membrane force as the external load. The formulation of the problem is given for a specially orthotropic material within the framework of a linearized shallow shell theory. The particular theory used permits the consideration of all five boundary conditions as to moment and stress resultants on the crack surface. The effect of Poisson's ratio on the stress intensity factors and the nature of the out-of-plane displacement along the edges of the crack, i.e., bulging, are also studied.

  5. The use of circumferentially varying stagger guide vanes in an axial flow pump or compressor

    Science.gov (United States)

    Horlock, J. H.

    1990-04-01

    An actuator disk analysis is given of the flow through a guide vane and rotor combination. It is shown that changes in total pressure across the rotor are, in general, related to circumferential variations in guide vane outlet angle. In particular, known variations in inlet total pressure may be eliminated by suitable circumferential changes in guide vane stagger.

  6. Angular-profile tuning of guided waves in hollow cylinders using a circumferential phased array.

    Science.gov (United States)

    Li, Jian; Rose, Joseph L

    2002-12-01

    Angular-profile tuning of guided waves in hollow cylinders is implemented by using partial loading of the elements in a circumferentially placed phased array. Each partial loading element generates nonaxisymmetric guided waves in a pipe. In earlier work, numerical calculations and experiments have shown that, for nonaxisymmetric guided waves, circumferential distribution of particle displacements (i.e., the angular profile) changes with propagation distance, frequency, and mode. To change the angular profile at a certain distance, either frequency or mode has to be changed for a single partial loading element. This is not the case, however, for a circumferential phased array. The total angular profile of a circumferential array is the superposition of contributions from all elements. If given the knowledge of the angular profile for a single element, the total guided wave angular profile can be controlled and thus focused at any specific circumferential location by a circumferentially placed phased array with adjustable voltage level and phase inputs. This angular profile tuning technique can be used for implementing a circumferential scan with focused, guided wave beams, which leads to the detection of smaller defects as a result of stronger focused beams. Algorithms and specific nondestructive evaluation (NDE) applications for pipe inspection using this technique are discussed.

  7. Fracture behavior of short circumferentially surface-cracked pipe

    Energy Technology Data Exchange (ETDEWEB)

    Krishnaswamy, P.; Scott, P.; Mohan, R. [Battelle, Columbus, OH (United States)] [and others

    1995-11-01

    This topical report summarizes the work performed for the Nuclear Regulatory Comniission`s (NRC) research program entitled ``Short Cracks in Piping and Piping Welds`` that specifically focuses on pipes with short, circumferential surface cracks. The following details are provided in this report: (i) material property deteminations, (ii) pipe fracture experiments, (iii) development, modification and validation of fracture analysis methods, and (iv) impact of this work on the ASME Section XI Flaw Evaluation Procedures. The material properties developed and used in the analysis of the experiments are included in this report and have been implemented into the NRC`s PIFRAC database. Six full-scale pipe experiments were conducted during this program. The analyses methods reported here fall into three categories (i) limit-load approaches, (ii) design criteria, and (iii) elastic-plastic fracture methods. These methods were evaluated by comparing the analytical predictions with experimental data. The results, using 44 pipe experiments from this and other programs, showed that the SC.TNP1 and DPZP analyses were the most accurate in predicting maximum load. New Z-factors were developed using these methods. These are being considered for updating the ASME Section XI criteria.

  8. Nonlinear giant magnetoimpedance and the asymmetric circumferential magnetization process in soft magnetic wires

    Science.gov (United States)

    Gómez-Polo, C.; Duque, J. G. S.; Knobel, M.

    2004-07-01

    The magnetoimpedance effect and its nonlinear terms are analysed for a (Co0.94Fe0.06)72.5Si12.5B15 amorphous wire. In order to enhance the nonlinear contribution the sample was previously subjected to current annealing (Joule heating) to induce a circumferential anisotropy. The effect of the application of a torsional strain on the nonlinear magnetoimpedance is analysed in terms of the torsional dependence of the magnetic permeability, evaluated through experimental circumferential hysteresis loops. The results obtained clearly confirm the direct correlation between the asymmetric circumferential magnetization process and the occurrence of nonlinear second-harmonic terms in the magnetoimpedance voltage.

  9. Design of optical cloaks and illusion devices along a circumferential direction in curvilinear coordinates

    Science.gov (United States)

    Chen, Tungyang; Yu, Shang-Ru

    2010-11-01

    We propose a cloaking and illusion device of circumferential topology based on the concept of transformation optics. The device is capable to cloak an object and/or simultaneously generate illusion images along a circumferential direction in curvilinear orthogonal coordinates. This feature allows us to construct multiple illusions in different ways, irrespective of the profile and direction of incident wave. Particularly when the device is served as a building brick of a larger device, one can generate a circumferential array of illusions in a periodic or any preferred pattern. We demonstrate the effectiveness of the proposed illusion devices by carrying out full wave simulations based on finite element calculations.

  10. Reduced Circumferential Resection Margin Involvement in Rectal Cancer Surgery: Results of the Dutch Surgical Colorectal Audit

    NARCIS (Netherlands)

    Gietelink, L.; Wouters, M.W.; Tanis, P.J.; Deken, M.M.; Berge, M.G. Ten; Tollenaar, R.A.; Krieken, J.H.J.M. van; Noo, M.E. de

    2015-01-01

    BACKGROUND: The circumferential resection margin (CRM) is a significant prognostic factor for local recurrence, distant metastasis, and survival after rectal cancer surgery. Therefore, availability of this parameter is essential. Although the Dutch total mesorectal excision trial raised awareness ab

  11. Variation in circumferential resection margin: Reporting and involvement in the South-Netherlands

    NARCIS (Netherlands)

    Homan, J.; Bokkerink, G.M.J.; Aarts, M.J.; Lemmens, V.E.; Lijnschoten, G. van; Rutten, H.J.; Wijsman, J.H.; Nagtegaal, I.D.; Wilt, J.H.W. de

    2015-01-01

    BACKGROUND: Since the introduction of total mesorectal surgery the outcome of rectal cancer patients has improved significantly. Involvement of the circumferential resection margin (CRM) is an important predictor of increased local recurrence, distant metastases and decreased overall survival. Abdom

  12. Effect of surface contamination on osseointegration of dental implants surrounded by circumferential bone defects.

    LENUS (Irish Health Repository)

    Mohamed, Seif

    2010-05-01

    This study was designed to evaluate the effect of surface contamination on osseointegration of dental implants surrounded by a circumferential bone defect and to compare osseointegration around Osseotite with that around Nanotite implants.

  13. ISSLS prize winner: cost-effectiveness of two forms of circumferential lumbar fusion

    DEFF Research Database (Denmark)

    Freeman, Brian J C; Steele, Nicholas A; Sach, Tracey H

    2007-01-01

    STUDY DESIGN: Economic evaluation alongside a prospective, randomized controlled trial from a secondary care National Health Service (NHS) perspective. OBJECTIVE: To determine the cost-effectiveness of titanium cages (TC) compared with femoral ring allografts (FRA) in circumferential lumbar spina...

  14. Effect of strength matching on the reliability of welded pipe with circumferential surface crack

    Institute of Scientific and Technical Information of China (English)

    何柏林; 于影霞; 霍立兴; 张玉凤

    2004-01-01

    For different strength matching, the reliability index and failure probability of welded pressure pipe with circumferential surface crack were calculated using three dimensional stochastic finite element method. This method has overcome the shortcomings of conservative results in safety assessment with deterministic fracture mechanics method. The effects of external moment and the depth of the circumferential surface crack (a) on the reliability of pressure pipe were also calculated and discussed. The calculation results indicate that the strength matching has certain effect on the reliability of the welded pressure pipe with circumferential surface crack. The failure probability of welded pressure pipe with high strength matching is lower than that with low strength matching at the same conditions. The effects of strength matching on the failure probability and reliability index increased by adding external moment (M) and the depth of the circumferential surface crack (a).

  15. Understanding the link between circumferential dikes and eruptive fissures around calderas based on numerical and analog models

    Science.gov (United States)

    Corbi, Fabio; Rivalta, Eleonora; Pinel, Virginie; Maccaferri, Francesco; Acocella, Valerio

    2016-06-01

    Active calderas are seldom associated with circumferential eruptive fissures, but eroded magmatic complexes reveal widespread circumferential dikes. This suggests that, while the conditions to emplace circumferential dikes are easily met, mechanisms must prevent them from reaching the surface. We explain this discrepancy with experiments of air injection into gelatin shaped as a volcano with caldera. Analog dikes show variable deflection, depending on the competition between overpressure, Pe, and topographic unloading, Pl; when Pl/Pe = 4.8-5.3, the dikes propagate orthogonal to the least compressive stress. Due to the unloading, they become circumferential and stall below the caldera rim; buoyancy is fundamental for the further rise and circumferential fissure development. Numerical models quantitatively constrain the stress orientation within the gelatin, explaining the observed circumferential dikes. Our results explain how dikes propagate below the rim of felsic and mafic calderas, but only in the latter they are prone to feed circumferential fissures.

  16. Analyses of axial, lateral and circumferential deformations of rock specimen in triaxial compression

    Institute of Scientific and Technical Information of China (English)

    WANG Xue-bin

    2008-01-01

    The axial, lateral and circumferential strains were analyzed for a rock specimen subjected to shear failure in the form of a shear band bisecting the specimen in triaxial compression. Plastic deformation of the specimen stemmed from shear strain localization initiated at the peak shear stress. Beyond the onset of strain localization, the axial, lateral and circumferential strains were decomposed into two parts, respectively. One is the elas-tic strain described by general Hooke's law. The other is attributable to the plastic shear slips along shear band with a certain thickness dependent on the internal length of rock.The post-peak circumferential strain-axial strain curve of longer specimen is steeper than that of shorter specimen, as is consistent with the previous experiments. In elastic stage,the circumferential strain-axial strain curve exhibits nonlinear characteristic, as is in agreement with the previous experiment since confining pressure is loaded progressively until a certain value is reached. When the confining pressure is loaded completely, the circumferential strain-axial strain curve is linear in elastic and strain-softening stages. The predicted circumferential strain-axial strain curve in elastic and strain- softening stages agrees with the previous experiment.

  17. Accelerated circumferential strain quantification of the left ventricle using CIRCOME: simulation and factor analysis

    Science.gov (United States)

    Moghaddam, Abbas N.; Finn, J. Paul

    2008-03-01

    Circumferential strain of the left ventricle reflects myocardial contractility and is considered a key index of cardiac function. It is also an important parameter in the quantitative evaluation of heart failure. Circumferential compression encoding, CIRCOME, is a novel method in cardiac MRI to evaluate this strain non-invasively and quickly. This strain encoding technique avoids the explicit measurement of the displacement field and does not require calculation of strain through spatial differentiation. CIRCOME bypasses these two time-consuming and noise sensitive steps by directly using the frequency domain (k-space) information from radially tagged myocardium, before and after deformation. It uses the ring-shaped crown region of the k-space, generated by the taglines, to reconstruct circumferentially compression-weighted images of the heart before and after deformation. CIRCOME then calculates the circumferential strain through relative changes in the compression level of corresponding regions before and after deformation. This technique can be implemented in 3D as well as 2D and may be employed to estimate the overall global or regional circumferential strain. The main parameters that affect the accuracy of this method are spatial resolution, signal to noise ratio, eccentricity of the center of radial taglines their fading and their density. Also, a variety of possible image reconstruction and filtering options may influence the accuracy of the method. This study describes the pulse sequence, algorithm, influencing factors and limiting criteria for CIRCOME and provides the simulated results.

  18. Circumferential myocardial strain in cardiomyopathy with and without left bundle branch block

    Directory of Open Access Journals (Sweden)

    Zimetbaum Peter J

    2010-01-01

    Full Text Available Abstract Background Cardiac resynchronization therapy (CRT has been shown to decrease mortality in 60-70% of advanced heart failure patients with left bundle branch block (LBBB and QRS duration > 120 ms. There have been intense efforts to find reproducible non-invasive parameters to predict CRT response. We hypothesized that different left ventricular contraction patterns may exist in LBBB patients with depressed systolic function and applied tagged cardiovascular magnetic resonance (CMR to assess circumferential strain in this population. Methods We determined myocardial circumferential strain at the basal, mid, and apical ventricular level in 35 subjects (10 with ischemic cardiomyopathy, 15 with non-ischemic cardiomyopathy, and 10 healthy controls. Patterns of circumferential strain were analyzed. Time to peak systolic circumferential strain in each of the 6 segments in all three ventricular slices and the standard deviation of time to peak strain in the basal and mid ventricular slices were determined. Results Dyskinesis of the anterior septum and the inferior septum in at least two ventricular levels was seen in 50% (5 out of 10 of LBBB patients while 30% had isolated dyskinesis of the anteroseptum, and 20% had no dyskinesis in any segments, similar to all of the non-LBBB patients and healthy controls. Peak circumferential strain shortening was significantly reduced in all cardiomyopathy patients at the mid-ventricular level (LBBB 9 ± 6%, non-LBBB 10 ± 4% vs. healthy 19 ± 4%; both p Conclusions Septal dyskinesis exists in some patients with LBBB. Myocardial circumferential strain analysis enables detailed characterization of contraction patterns, strengths, and timing in cardiomyopathy patients with and without LBBB.

  19. Self-Reacting Friction Stir Welding for Aluminum Alloy Circumferential Weld Applications

    Science.gov (United States)

    Bjorkman, Gerry; Cantrell, Mark; Carter, Robert

    2003-01-01

    Friction stir welding is an innovative weld process that continues to grow in use, in the commercial, defense, and space sectors. It produces high quality and high strength welds in aluminum alloys. The process consists of a rotating weld pin tool that plasticizes material through friction. The plasticized material is welded by applying a high weld forge force through the weld pin tool against the material during pin tool rotation. The high weld forge force is reacted against an anvil and a stout tool structure. A variation of friction stir welding currently being evaluated is self-reacting friction stir welding. Self-reacting friction stir welding incorporates two opposing shoulders on the crown and root sides of the weld joint. In self-reacting friction stir welding, the weld forge force is reacted against the crown shoulder portion of the weld pin tool by the root shoulder. This eliminates the need for a stout tooling structure to react the high weld forge force required in the typical friction stir weld process. Therefore, the self-reacting feature reduces tooling requirements and, therefore, process implementation costs. This makes the process attractive for aluminum alloy circumferential weld applications. To evaluate the application of self-reacting friction stir welding for aluminum alloy circumferential welding, a feasibility study was performed. The study consisted of performing a fourteen-foot diameter aluminum alloy circumferential demonstration weld using typical fusion weld tooling. To accomplish the demonstration weld, weld and tack weld development were performed and fourteen-foot diameter rings were fabricated. Weld development consisted of weld pin tool selection and the generation of a process map and envelope. Tack weld development evaluated gas tungsten arc welding and friction stir welding for tack welding rings together for circumferential welding. As a result of the study, a successful circumferential demonstration weld was produced leading

  20. An analysis of the Circumferential Grooves Casing Treatment for transonic compressor flow

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The stall mechanism of the NASA Rotor 37 is investigated through the analysis of the critical flow structures near the stall under the transonic condition. The performance of the rotor with Circumferential Grooves Casing Treatment (CGCT) is also studied based on the Reynolds-Averaging Navier-Stokes approach. The study finds that stall margin improvement can be achieved without significant penalty on the efficiency for the two CGCT configurations applied. The effects of circumferential grooves on the critical flow structures are studied through the analysis of the tip leakage mass and momentum transport that further re-veal the CGCT mechanism.

  1. A second patient with MCA/MR syndrome with multiple circumferential skin creases.

    Science.gov (United States)

    Leonard, N J

    2002-09-15

    Symmetrical congenital circumferential skin creases are a rare feature described in only a few conditions. We report a case of a 29-month-old boy with symmetrical circumferential skin creases on arms, legs, and digits, and other features reminiscent of the single case reported by Cohen et al. [1993: Clin Dysmorphol 2:39-46] and reviewed by Elliott et al. [1996: Am J Med Genet 62:23-25]. The key features also include epicanthic folds, microphthalmia, microcornea, microcephaly, small, low-set posteriorly angulated ears with thick overfolded helices, cleft palate, and moderate-severe psychomotor developmental delay.

  2. Optimization of the axial compressor flow passage to reduce the circumferential distortion

    Science.gov (United States)

    Popov, G.; Kolmakova, D.; Shklovets, A.; Ermakov, A.

    2015-08-01

    This work is motivated by the necessity to reduce the effects of the flow circumferential distortion in the flow passage of the aircraft gas turbine engine (GTE). In previous research, the authors have proposed the approaches to decrease of the flow circumferential distortion arising from the mid-support racks of GTE compressor and having a negative impact on the blade rows, located upstream. In particular, the idea of introducing the circumferentially non-uniform blade pitch and profile stagger angle of guide vanes located in front of the support was contributed in order to redistribute the flow and decrease the dynamic stresses in the rotor wheel of the same stage. During the research presented in this paper, another principal of reduction of the flow circumferential distortion was chosen. Firstly, the variants of upgrading the existing support racks were found. Secondly, the new design of support was offered. Both the first and the second version of the support design variation took into account the availability of technological and structural limitations associated with the location of oil pipes, springs and others elements in the support racks. Investigations of modified design showed that the support with altered racks provides a reduction of dynamic stresses by 20% at resonance with the most dangerous harmonic, and the new design of support can give the decrease of 30%.

  3. Numerical Simulation of the Flow Field in Circumferential Grooved Liquid Seals

    Directory of Open Access Journals (Sweden)

    Meng Zhang

    2013-01-01

    Full Text Available Circumferential grooved liquid seals are utilized inside turbomachinery to provide noncontacting control of internal incompressible fluid leakage. Accurate prediction of the flow field is fundamental in producing robust and efficient designs. To validate the capabilities of the computational fluid dynamics FLUENT for incompressible fluid seal flow, comparisons of velocity parameters are made to the published experimental results and other CFD code for a circumferential grooved liquid seal. This work employs a pressure-based CFD code FLUENT to calculate the flow field in the seal, using four different turbulence models respectively. The velocity contours are compared with experimental values. It shows good overall agreement of the axial, radial, and azimuthal velocities in the through-flow jet, shear layer, and recirculation zone. Quantitative comparisons of velocity profiles at the center of the groove are made to experiment. This study verifies the prediction accuracy of three turbulence models. Various structures were considered to obtain a better understanding of the circumferential grooved liquid flow characteristics. The best groove structure to control leakage was also found within the limited designed seal. This study will provide a useful reference for designing the circumferential grooved liquid seal.

  4. Conventional CT for the prediction of an involved circumferential resection margin in primary rectal cancer

    NARCIS (Netherlands)

    Wolberink, Steven V. R. C.; Beets-Tan, Regina G. H.; de Haas-Kock, Danielle F. M.; Span, Mark M.; van de Jagt, Eric J.; van de Velde, Cornelis J. H.; Wiggers, Theo

    2007-01-01

    Purpose: To determine the accuracy of conventional computed tomography (CT) scan in the preoperative prediction of an involved circumferential resection margin (CRM) in primary rectal cancer. Methods: 125 patients with biopsy-proven adenocarcinoma of the rectum underwent CT of the abdomen before und

  5. Circumferential optical coherence tomography angiography imaging of the swine esophagus using a micromotor balloon catheter.

    Science.gov (United States)

    Lee, Hsiang-Chieh; Ahsen, Osman Oguz; Liang, Kaicheng; Wang, Zhao; Cleveland, Cody; Booth, Lucas; Potsaid, Benjamin; Jayaraman, Vijaysekhar; Cable, Alex E; Mashimo, Hiroshi; Langer, Robert; Traverso, Giovanni; Fujimoto, James G

    2016-08-01

    We demonstrate a micromotor balloon imaging catheter for ultrahigh speed endoscopic optical coherence tomography (OCT) which provides wide area, circumferential structural and angiographic imaging of the esophagus without contrast agents. Using a 1310 nm MEMS tunable wavelength swept VCSEL light source, the system has a 1.2 MHz A-scan rate and ~8.5 µm axial resolution in tissue. The micromotor balloon catheter enables circumferential imaging of the esophagus at 240 frames per second (fps) with a ~30 µm (FWHM) spot size. Volumetric imaging is achieved by proximal pullback of the micromotor assembly within the balloon at 1.5 mm/sec. Volumetric data consisting of 4200 circumferential images of 5,000 A-scans each over a 2.6 cm length, covering a ~13 cm(2) area is acquired in <18 seconds. A non-rigid image registration algorithm is used to suppress motion artifacts from non-uniform rotational distortion (NURD), cardiac motion or respiration. En face OCT images at various depths can be generated. OCT angiography (OCTA) is computed using intensity decorrelation between sequential pairs of circumferential scans and enables three-dimensional visualization of vasculature. Wide area volumetric OCT and OCTA imaging of the swine esophagus in vivo is demonstrated.

  6. Mechanical characterization of human aortas from pressurization testing and a paradigm shift for circumferential residual stress.

    Science.gov (United States)

    Labrosse, Michel R; Gerson, Eleanor R; Veinot, John P; Beller, Carsten J

    2013-01-01

    Material properties needed for accurate stress analysis of the human aorta are still incompletely known, especially as many reports have ignored the presence of residual stresses in the aortic wall. To contribute new material regarding these issues, we carried out measurements and pressurization testing on ascending, thoracic and abdominal aortic samples from 24 human subjects aged 38-77 years, and evaluated the opening angle describing the circumferential residual stress level present in the aorta. We determined material constants for the aorta by gender, anatomic location and age group, according to a simple phenomenological constitutive model. The unpressurized aortic radius positively correlated with age, and the circumferential and longitudinal stretch ratios under systemic pressure negatively correlated with age, confirming the known enlargement and stiffening of the aorta with aging. The opening angle was measured to range from a minimum of 89° to above 360° for extreme cases. For given aortic dimensions and material properties, analysis of the in vivo circumferential and longitudinal mural stress distributions indicated a profound influence of the opening angle. For instance, in the thoracic aorta of males aged 38-66, opening angles in the range of 0° to 80° (resp. 60°) may equalize the gradient of in vivo circumferential (resp. longitudinal) stress between the inner and outer layers of the aorta, as commonly expected; however, opening angles above 160° (resp. 120°) may cause the gradient of circumferential (resp. longitudinal) stress to reverse and increase compared to the case without residual stress, putting the maximum stresses toward the adventitia instead of the intima. Even though the analysis of the aortic wall excluded possible longitudinal residual stresses as well as material inhomogeneities, such as constitutive differences between the intimal, medial and adventitial layers, the experimental data reported herein are important to aortic

  7. Skin resurfacing in a circumferential full thickness burn to the penis: lessons learnt.

    Science.gov (United States)

    Jabir, Shehab; Frew, Quentin; Thompson, Richard; Dziewulski, Peter

    2013-08-13

    A circumferential full-thickness burn to the penis is a rarely encountered injury. However, when it does occur, it proves a management challenge to the plastic and burns surgeon in terms of reconstruction. This is due to the need of not only regaining adequate function of the organ, but also because of the need for a pleasing aesthetic outcome. Split-skin grafts have been utilised successfully to resurface full thickness burns of the penis and have given good results. Yet the success of split-skin grafts, especially those applied to an anatomically challenging region of the body such as the penis, depends on a number of carefully thought-out steps. We discuss the case of a circumferential full-thickness burn to the penis which was treated with split-skin grafting and highlight important pitfalls that the plastic and burns surgeon need to be aware of to ensure a successful outcome.

  8. Prediction of leakage and rotordynamic coefficients for the circumferential-groove pump seal using CFD analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung Ho; Ha, Tae Woong [Gachon University, Seongnam (Korea, Republic of)

    2016-05-15

    The circumferential-groove seal is commonly used in various turbopumps to reduce leakage. The main goal of this paper is to develop the method of three-dimensional CFD analysis for determining leakage and rotordynamic coefficients of the circumferential-groovepump seal. A relative coordinate system was defined for steady-state simulation to calculate the velocity and pressure distributions of the seal clearance at each rotor whirl speed. Instead of setting the inlet and outlet pressures as the boundary conditions in the three dimensional CFD analysis, as it is more commonly done, we used the inlet velocity and outlet pressure obtained from a preliminary two dimensional CFD analysis. For prediction leakage, the presented analysis shows improvement from the bulk-flow model analysis. For the prediction of rotordynamic coefficients of K, k and C, the presented analysis provides results in closer agreement with the experimental values than those of the bulk-flow model analysis at several rotor speeds.

  9. Circumferential mucosal dissection and esophageal perforation in a patient with eosinophilic esophagitis

    Institute of Scientific and Technical Information of China (English)

    Gennaro Liguori; Maurizio Cortale; Fabrizio Cimino; Michele Sozzi

    2008-01-01

    A young man with a previous history of episodes of mild solid food dysphagia was admitted with a total dysphagia.The esophagogastroduodenoscopy (EGDS) showed an extensive disruption of mucosal layer with a cul-de-sac in the lower part of the esophagus.Soon after the procedure,the patient suffered from an acute chest pain and subsequent CT scan demonstrated an intramural circumferential dissection of thoracic esophagus,and a mediastinal emphysema.An emergency right thoracotomy was performed,followed by a total esophagectomy with esophagogastroplasty and jejunostomy.The histopathology confirmed that mucosal and submucosal layers were circumferentially detached from muscular wall and showed an eosinophilic infiltration of the whole organ with necrosis and erosions of mucosal,submucosal and muscular layers.The diagnosis was esophageal perforation in eosinophilic esophagitis.

  10. [Echocardiographic longitudinal, radial, circumferential and rotational synchronization disturbance in predicting response to cardiac resynchronization therapy].

    Science.gov (United States)

    Sade, Leyla Elif

    2010-02-01

    Several echocardiographic methods have been proposed to assist patient selection for cardiac resynchronization therapy. Color-coded tissue Doppler is one of the most promising methods to quantify mechanical dyssynchrony. However, tissue Doppler data are affected by Doppler angle of incidence and tethering or translational motion. Furthermore tissue Doppler based modalities are good for longitudinal motion analysis but limited in other directions of wall motion such as radial, circumferential, and rotational. Speckle tracking is a more recent technique that allows accurate calculation of regional radial and circumferential strain as well as regional rotation for dyssynchrony analysis. Although no ideal echocardiographic method exists that integrates regional dyssynchrony data in all contraction directions as yet, technical refinements and advances in understanding of pathophysiology will help to improve the study of mechanical dyssynchrony.

  11. In vivo vascular wall shear rate and circumferential strain of renal disease patients.

    Science.gov (United States)

    Park, Dae Woo; Kruger, Grant H; Rubin, Jonathan M; Hamilton, James; Gottschalk, Paul; Dodde, Robert E; Shih, Albert J; Weitzel, William F

    2013-02-01

    This study measures the vascular wall shear rate at the vessel edge using decorrelation based ultrasound speckle tracking. Results for nine healthy and eight renal disease subjects are presented. Additionally, the vascular wall shear rate and circumferential strain during physiologic pressure, pressure equalization and hyperemia are compared for five healthy and three renal disease subjects. The mean and maximum wall shear rates were measured during the cardiac cycle at the top and bottom wall edges. The healthy subjects had significantly higher mean and maximum vascular wall shear rate than the renal disease subjects. The key findings of this research were that the mean vascular wall shear rates and circumferential strain changes between physiologic pressure and hyperemia that was significantly different between healthy and renal disease subjects.

  12. Influence of the heart rate on mean circumferential shortening velocity: echocardiographic study of 183 normal subjects.

    Science.gov (United States)

    Mangiarotti, R; Martinotti, R; Monzani, V; Sardella, F; Pierini, A; Pastori, M; Randazzo, A

    1986-01-01

    Echocardiography was used to explore the influence of independent variables (age, body surface area and heart rate) on the mean circumferential shortening velocity (MVCF) in 183 healthy subjects. Multiple stepwise regression analysis shows that heart rate is the only variable of the three just mentioned that influences MVCF. A regression equation is evolved and proposed as an index of MVCF correction for varying heart rates.

  13. Selective radiofrequency therapy as a non-invasive approach for contactless body contouring and circumferential reduction.

    Science.gov (United States)

    Fajkošová, Kateřina; Machovcová, Alena; Onder, Meltem; Fritz, Klaus

    2014-03-01

    In this study, the efficacy of non-contact, selective radiofrequency (RF) were evaluated for body contouring as non-invasive fat and circumferential reduction of the abdomen. 40 healthy (36 female, 4 male) subjects showing significant volume of subcutaneous fat tissue on the abdomen and waistline were included. Once a week for 30 minutes, 4 sessions were performed. The applicator was placed on a supplied spacer covering the treatment area. Maximum power was 200W, which induced heat in the fat and connective tissue layer. The homogeneity of heat distribution and temperature of the skin surface were controlled. The circumferential reduction was measured at the baseline and after the last treatment. The photographs and adverse effects were recorded. Participants completed the self-evaluation questionnaires and rated their level of satisfaction. All subjects tolerated the treatments well. The only side effect was mild to moderate erythema. 35 subjects finished the protocol as planned and 5 subjects dropped off due to events not related to the study. 32 subjects had a 1-13 cm decrease in abdominal circumference and 3 subjects did not show significant response (0-1 cm). Most likely, a very thin fat layer was the reason for lack of response (the non-responding group was the thinnest patient group). No significant differences were found between men and women. The average decrease of 4.93 cm was calculated as a result of circumferential reduction statistical evidence. This study demonstrates that the selective RF system designed for contactless deep tissue heating is a painless, safe, and effective treatment for non-surgical body contouring and circumferential fat reduction.

  14. Numerical Investigation of Inlet Distortion on an Axial Flow Compressor Rotor with Circumferential Groove Casing Treatment

    Institute of Scientific and Technical Information of China (English)

    Huang Jian; Wu Hu

    2008-01-01

    On the base of an assumed steady inlet circumferential total pressure distortion, three-dimensional time-dependent numerical simulations are conducted on an axial flow subsonic compressor rotor. The performances and flow fields of a compressor rotor, either casing treated or untreated, are investigated in detail either with or without inlet pressure distortion. Results show that the circumferential groove casing treatment can expand the operating range of the compressor rotor either with or without inlet pressure distortion at the expense of a drop in peak isentropic efficiency. The casing treatment is capable of weakening or even removing the tip leakage vortex effectively either with or without inlet distortion. In clean inlet circumstances, the enhancement and forward movement of tip leakage vortex cause the untreated compressor rotor to stall. By contrast, with circumferential groove casing, the serious flow separation on the suction surface leads to aerodynamic stalling eventually. In the presence of inlet pressure distortion, the blade loading changes from passage to passage as the distorted inflow sector is traversed. Similar to the clean inlet circumstances, with a smooth wall casing, the enhancement and forward movement of tip leakage vortex are still the main factors which lead to the compressor rotor stalling eventu-ally. When the rotor works under near stall conditions, the blockage resulting from the tip leakage vortex in all the passages is very seri-ous. Especially in several passages, flow-spillage is observed. Compared to the clean inlet circumstances, circumferential groove casing treatment can also eliminate the low energy zone in the outer end wall region effectively.

  15. Circumferential-wave phase velocities for empty, fluid-immersed spherical metal shells

    DEFF Research Database (Denmark)

    Überall, Herbert; Ahyi, A. C.; Raju, P. K.

    2002-01-01

    -loaded, evacuated spherical metal shells of aluminum, stainless steel, and tungsten carbide. In particular, the characteristic upturn of the dispersion curves of low-order shell-borne circumferential waves (A or A0 waves) which takes place on spherical shells when the frequency tends towards very low values......, is demonstrated here for all cases of the metals under consideration. ©2002 Acoustical Society of America....

  16. Nonlinear vibrations and energy exchange of single-walled carbon nanotubes. Circumferential flexural modes

    Science.gov (United States)

    Strozzi, Matteo; Smirnov, Valeri V.; Manevitch, Leonid I.; Milani, Massimo; Pellicano, Francesco

    2016-10-01

    In this paper, the nonlinear vibrations and energy exchange of single-walled carbon nanotubes (SWNTs) are studied. The Sanders-Koiter theory is applied to model the nonlinear dynamics of the system in the case of finite amplitude of vibration. The SWNT deformation is described in terms of longitudinal, circumferential and radial displacement fields. Simply supported, clamped and free boundary conditions are considered. The circumferential flexural modes (CFMs) are investigated. Two different approaches based on numerical and analytical models are compared. In the numerical model, an energy method based on the Lagrange equations is used to reduce the nonlinear partial differential equations of motion to a set of nonlinear ordinary differential equations, which is solved by using the implicit Runge-Kutta numerical method. In the analytical model, a reduced form of the Sanders-Koiter theory assuming small circumferential and tangential shear deformations is used to get the nonlinear ordinary differential equations of motion, which are solved by using the multiple scales analytical method. The transition from energy beating to energy localization in the nonlinear field is studied. The effect of the aspect ratio on the analytical and numerical values of the nonlinear energy localization threshold for different boundary conditions is investigated. Time evolution of the total energy distribution along the axis of a simply supported SWNT

  17. Circumferential phased array of shear-horizontal wave magnetostrictive patch transducers for pipe inspection.

    Science.gov (United States)

    Kim, Hoe Woong; Lee, Joo Kyung; Kim, Yoon Young

    2013-02-01

    Several investigations report effective uses of magnetostrictive patch transducers to generate and measure longitudinal and torsional guided waves in a pipe. They can be used to form a phased array for the circumferential inspection of pipes. Although there are circumferential phased arrays employing piezoelectric transducers or EMAT's, no magnetostrictive patch transducer based array system has been attempted. In this investigation, we aim to develop a circumferential phased magnetostrictive patch transducer (PMPT) array that can focus shear-horizontal waves at any target point on a cylindrical surface of a pipe. For the development, a specific configuration of a PMPT array employing six magnetostrictive patch transducers is proposed. A wave simulation model is also developed to determine time delays and amplitudes of signals generated by the transducers of the array. This model should be able to predict accurately the angular profiles of shear-horizontal waves generated by the transducers. For wave focusing, the time reversal idea will be utilized. The wave focusing ability of the developed PMPT array is tested with multiple-crack detection experiments. Imaging of localized surface inspection regions is also attempted by using wave signals measured by the developed PMPT array system.

  18. Soft Sensor for Oxide Scales on the Steam Side of Superheater Tubes under Uneven Circumferential Load

    Directory of Open Access Journals (Sweden)

    Qing Wei Li

    2015-01-01

    Full Text Available A soft sensor for oxide scales on the steam side of superheater tubes of utility boiler under uneven circumferential loading is proposed for the first time. First finite volume method is employed to simulate oxide scales growth temperature on the steam side of superheater tube. Then appropriate time and spatial intervals are selected to calculate oxide scales thickness along the circumferential direction. On the basis of the oxide scale thickness, the stress of oxide scales is calculated by the finite element method. At last, the oxide scale thickness and stress sensors are established on support vector machine (SMV optimized by particle swarm optimization (PSO with time and circumferential angles as inputs and oxide scale thickness and stress as outputs. Temperature and stress calculation methods are validated by the operation data and experimental data, respectively. The soft sensor is applied to the superheater tubes of some power plant. Results show that the soft sensor can give enough accurate results for oxide scale thickness and stress in reasonable time. The forecasting model provides a convenient way for the research of the oxide scale failure.

  19. Lumbar extracavitary corpectomy with a single stage circumferential arthrodesis: surgical technique and clinical series.

    Science.gov (United States)

    Singh, Kern; Park, Daniel K

    2012-07-01

    Circumferential arthrodesis and reconstruction is necessary after a lumbar corpectomy in the setting of malignancy and infection. The advent of expandable cage technology now allows for safe anterior column reconstruction via a posterior approach with no transection and minimal retraction of the lumbar spinal nerve roots. Fifteen patients underwent a single-stage, circumferential corpectomy and anterior spinal reconstruction with an expandable cage via a midline, posterior, lateral lumbar extracavitary approach. Posterior segmental pedicle screw fixation and iliac crest bone graft was used in all cases. Fifteen lumbar extracavitary corpectomy nerve root-sparing procedures have been performed to date, with at least 1-year follow-up (12 tumors/3 infections). No patient suffered any neurological complications. One patient suffered from a postoperative myocardial infarction 10 days after the procedure. Two patients had medical complications that were treated without sequelae. We present a technical description and case series of patients undergoing a single-stage, circumferential corpectomy and anterior spinal reconstruction with an expandable cage via a midline, posterior, lateral lumbar extracavitary approach with at least 1-year follow-up. The technique is safe, technically feasible, and obviates an anterior approach in this oftentimes critically ill patient population.

  20. Functional evaluation of repairs to circumferential labral lesions of the glenoid - Case series

    Directory of Open Access Journals (Sweden)

    Alexandre Tadeu do Nascimento

    Full Text Available ABSTRACT OBJECTIVE: To evaluate the clinical results among patients undergoing arthroscopic repair of circumferential labral lesions. METHODS: This was a retrospective study on 10 patients who underwent arthroscopic repair to circumferential labral lesions of the shoulder, between September 2012 and September 2015. The patients were evaluated by means of the Carter-Rowe score, DASH score, UCLA score, visual analog scale (VAS for pain and Short-Form 36 (SF36. The average age at surgery was 29.6 years. The mean follow-up was 27.44 months (range: 12-41.3. RESULTS: The mean score was 16 points for DASH; 32 points for UCLA, among which six patients (60% had excellent results, three (30% good and one (10% poor; 1.8 points for VAS, among which nine patients (90% had minor pain and one (10% moderate pain; 79.47 for SF-36; and 92.5 for Carter-Rowe, among which nine patients (90% had excellent results and one (10% good. Joint degeneration was present in one case (10%, of grade 1. We did not observe any significant complications, except for grade 1 glenohumeral arthrosis, which one patient developed after the operation. CONCLUSION: Arthroscopic repair of circumferential labral lesions of the shoulder through use of absorbable anchors is effective, with improvements in all scores applied, and it presents low complication rates. Cases associated with glenohumeral dislocation have lower long-term residual pain.

  1. Numerical Simulation for Three-Dimensional (3D) Unsteady State Temperature Field in Circumferential Laser Oxygen Cutting of Pipes

    Institute of Scientific and Technical Information of China (English)

    Kaijin HUANG; Dawen ZENG; Changsheng XIE; Desheng XU

    2003-01-01

    A 3D unsteady state numerical model of heat transfer in the circumferential laser oxygen cutting of pipes wasdeveloped. In order to minimize the computing time required for solving the finite difference equations as much aspossible, the alternating direct

  2. On guided circumferential waves in soft electroactive tubes under radially inhomogeneous biasing fields

    Science.gov (United States)

    Wu, Bin; Su, Yipin; Chen, Weiqiu; Zhang, Chuanzeng

    2017-02-01

    Soft electroactive (EA) tube actuators and many other cylindrical devices have been proposed recently in literature, which show great advantages over those made from conventional hard solid materials. However, their practical applications may be limited because these soft EA devices are prone to various failure modes. In this paper, we present an analysis of the guided circumferential elastic waves in soft EA tube actuators, which has potential applications in the in-situ nondestructive evaluation (NDE) or online structural health monitoring (SHM) to detect structural defects or fatigue cracks in soft EA tube actuators and in the self-sensing of soft EA tube actuators based on the concept of guided circumferential elastic waves. Both circumferential SH and Lamb-type waves in an incompressible soft EA cylindrical tube under inhomogeneous biasing fields are considered. The biasing fields, induced by the application of an electric voltage difference to the electrodes on the inner and outer cylindrical surfaces of the EA tube in addition to an axial pre-stretch, are inhomogeneous in the radial direction. Dorfmann and Ogden's theory of nonlinear electroelasticity and the associated linear theory for small incremental motion constitute the basis of our analysis. By means of the state-space formalism for the incremental wave motion along with the approximate laminate technique, dispersion relations are derived in a particularly efficient way. For a neo-Hookean ideal dielectric model, the proposed approach is first validated numerically. Numerical examples are then given to show that the guided circumferential wave propagation characteristics are significantly affected by the inhomogeneous biasing fields and the geometrical parameters. Some particular phenomena such as the frequency veering and the nonlinear dependence of the phase velocity on the radial electric voltage are discussed. Our numerical findings demonstrate that it is feasible to use guided circumferential

  3. Posterior-Only Circumferential Decompression and Reconstruction in the Surgical Management of Lumbar Vertebral Osteomyelitis

    Science.gov (United States)

    Skovrlj, Branko; Guzman, Javier Z.; Caridi, John; Cho, Samuel K.

    2015-01-01

    Study Design Case report. Objective The purpose of this report is to discuss the surgical management of lumbar vertebral osteomyelitis with a spinal epidural abscess (SEA) and present a single-stage, posterior-only circumferential decompression and reconstruction with instrumentation using an expandable titanium cage and without segmental nerve root sacrifice as an option in the treatment of this disease process. Methods We report a 42-year-old man who presented with 3 days of low back pain and chills who rapidly decompensated with severe sepsis following admission. Magnetic resonance imaging of his lumbosacral spine revealed intramuscular abscesses of the left paraspinal musculature and iliopsoas with SEA and L4 vertebral body involvement. The patient failed maximal medical treatment, which necessitated surgical treatment as a last resort for infectious source control. He underwent a previously undescribed procedure in the setting of SEA: a single-stage, posterior-only approach for circumferential decompression and reconstruction of the L4 vertebral body with posterior segmental instrumented fixation. Results After the surgery, the patient's condition gradually improved; however, he suffered a wound dehiscence necessitating a surgical exploration and deep wound debridement. Six months after the surgery, the patient underwent a revision surgery for adjacent-level pseudarthrosis. At 1-year follow-up, the patient was pain-free and off narcotic pain medication and had returned to full activity. Conclusion This patient is the first reported case of lumbar osteomyelitis with SEA treated surgically with a single-stage, posterior-only circumferential decompression and reconstruction with posterior instrumentation. Although this approach is more technically challenging, it presents another viable option for the treatment of lumbar vertebral osteomyelitis that may reduce the morbidity associated with an anterior approach. PMID:26835214

  4. Magnetic resonance imaging characterization of circumferential and longitudinal strain under various coronary interventions in swine

    Institute of Scientific and Technical Information of China (English)

    Mohammed; SA; Suhail; Mark; W; Wilson; Steven; W; Hetts; Maythem; Saeed

    2013-01-01

    AIM:To compare the acute changes in circumferential and longitudinal strain after exposing a coronary artery to various interventions in swine.METHODS:Percutaneous balloon angioplasty catheter was guided to location aid device(LAD)under X-ray fluoroscopy to create different patterns of ischemic insults.Pigs(n=32)were equally divided into 4 groups:controls,90 min LAD occlusion/reperfusion,LAD microembolization,and combined LAD occlusion/microembolization/reperfusion.Three days after interventions,cine,tagged and viability magnetic resonance imaging(MRI)were acquired to measure and compare left and right circumferential strain,longitudinal strain and myocardial viability,respectively.Measurements were obtained using HARP and semi-automated threshold method and statistically analyzed using unpaired t-test.Myocardial and vascular damage was characterized microscopically.RESULTS:Coronary microemboli caused greater impairment in l left ventricular(LV)circumferential strain and dyssynchrony than LAD occlusion/reperfusion despite the significant difference in the extent of myocardial damage.Microemboli also caused significant decrease in peak systolic strain rate of remote myocardium and LV dyssynchrony.Cine MRI demonstrated the interaction between LV and right ventricular(RV)at 3 d after interventions.Compensatory increase in RV free wall longitudinal strain was seen in response to all interventions.Viability MRI,histochemical staining and microscopy revealed different patterns of myocardial damage and microvascular obstruction.CONCLUSION:Cine MRI revealed subtle changes in LV strain caused by various ischemic insults.It also demonstrated the interaction between the right and left ventricles after coronary interventions.Coronary microemboli with and without acute myocardial infarction(AMI)cause complex myocardial injury and ventricular dysfunction that is not replicated in solely AMI.

  5. Investigations on an Axial Flow Fan Stage subjected to Circumferential Inlet Flow Distortion and Swirl

    Institute of Scientific and Technical Information of China (English)

    M.Govardhan; K.Viswanath

    1997-01-01

    The combined effects of swirl and circumferential inlet flow distortion on the flow field of an axial flow fan stage are reported in this paper,The study involves measurements at the inlet of the rotor and exit of the rotor and stator atdesign and off design flow conditions.The study indicated that at the design flow condition,swirl had caused deterioration of the performance in addition to that caused by distortion.Pressure rise imparted in the distortion zone is hogher than in the free zone.The attenuation of distortion is high in the presence of swirl.

  6. Estimation of leak rate through circumferential cracks in pipes in nuclear power plants

    Directory of Open Access Journals (Sweden)

    Jai Hak Park

    2015-04-01

    Full Text Available The leak before break (LBB concept is widely used in designing pipe lines in nuclear power plants. According to the concept, the amount of leaking liquid from a pipe should be more than the minimum detectable leak rate of a leak detection system before catastrophic failure occurs. Therefore, accurate estimation of the leak rate is important to evaluate the validity of the LBB concept in pipe line design. In this paper, a program was developed to estimate the leak rate through circumferential cracks in pipes in nuclear power plants using the Henry–Fauske flow model and modified Henry–Fauske flow model. By using the developed program, the leak rate was calculated for a circumferential crack in a sample pipe, and the effect of the flow model on the leak rate was examined. Treating the crack morphology parameters as random variables, the statistical behavior of the leak rate was also examined. As a result, it was found that the crack morphology parameters have a strong effect on the leak rate and the statistical behavior of the leak rate can be simulated using normally distributed crack morphology parameters.

  7. Mutations in Either TUBB or MAPRE2 Cause Circumferential Skin Creases Kunze Type

    Science.gov (United States)

    Isrie, Mala; Breuss, Martin; Tian, Guoling; Hansen, Andi Harley; Cristofoli, Francesca; Morandell, Jasmin; Kupchinsky, Zachari A.; Sifrim, Alejandro; Rodriguez-Rodriguez, Celia Maria; Dapena, Elena Porta; Doonanco, Kurston; Leonard, Norma; Tinsa, Faten; Moortgat, Stéphanie; Ulucan, Hakan; Koparir, Erkan; Karaca, Ender; Katsanis, Nicholas; Marton, Valeria; Vermeesch, Joris Robert; Davis, Erica E.; Cowan, Nicholas J.; Keays, David Anthony; Van Esch, Hilde

    2015-01-01

    Circumferential skin creases Kunze type (CSC-KT) is a specific congenital entity with an unknown genetic cause. The disease phenotype comprises characteristic circumferential skin creases accompanied by intellectual disability, a cleft palate, short stature, and dysmorphic features. Here, we report that mutations in either MAPRE2 or TUBB underlie the genetic origin of this syndrome. MAPRE2 encodes a member of the microtubule end-binding family of proteins that bind to the guanosine triphosphate cap at growing microtubule plus ends, and TUBB encodes a β-tubulin isotype that is expressed abundantly in the developing brain. Functional analyses of the TUBB mutants show multiple defects in the chaperone-dependent tubulin heterodimer folding and assembly pathway that leads to a compromised yield of native heterodimers. The TUBB mutations also have an impact on microtubule dynamics. For MAPRE2, we show that the mutations result in enhanced MAPRE2 binding to microtubules, implying an increased dwell time at microtubule plus ends. Further, in vivo analysis of MAPRE2 mutations in a zebrafish model of craniofacial development shows that the variants most likely perturb the patterning of branchial arches, either through excessive activity (under a recessive paradigm) or through haploinsufficiency (dominant de novo paradigm). Taken together, our data add CSC-KT to the growing list of tubulinopathies and highlight how multiple inheritance paradigms can affect dosage-sensitive biological systems so as to result in the same clinical defect. PMID:26637975

  8. Fracture behavior of circumferentially surface-cracked elbows. Technical report, October 1993--March 1996

    Energy Technology Data Exchange (ETDEWEB)

    Kilinski, T.; Mohan, R.; Rudland, D.; Fleming, M. [and others

    1996-12-01

    This report presents the results from Task 2 of the Second International Piping Integrity Research Group (IPIRG-2) program. The focus of the Task 2 work was directed towards furthering the understanding of the fracture behavior of long-radius elbows. This was accomplished through a combined analytical and experimental program. J-estimation schemes were developed for both axial and circumferential surface cracks in elbows. Large-scale, quasi-static and dynamic, pipe-system, elbow fracture experiments under combined pressure and bending loads were performed on elbows containing an internal surface crack at the extrados. In conjunction with the elbow experiments, material property data were developed for the A106-90 carbon steel and WP304L stainless steel elbow materials investigated. A comparison of the experimental data with the maximum stress predictions using existing straight pipe fracture prediction analysis methods, and elbow fracture prediction methods developed in this program was performed. This analysis was directed at addressing the concerns regarding the validity of using analysis predictions developed for straight pipe to predict the fracture stresses of cracked elbows. Finally, a simplified fitting flaw acceptance criteria incorporating ASME B2 stress indices and straight pipe, circumferential-crack analysis was developed.

  9. Experimental investigation on circumferential and axial temperature gradient over fuel channel under LOCA

    Science.gov (United States)

    Yadav, Ashwini Kumar; kumar, Ravi; Gupta, Akhilesh; Chatterjee, Barun; Mukhopadhyay, Deb; Lele, H. G.

    2014-06-01

    In a nuclear reactor temperature rises drastically in fuel channels under loss of coolant accident due to failure of primary heat transportation system. Present investigation has been carried out to capture circumferential and axial temperature gradients during fully and partially voiding conditions in a fuel channel using 19 pin fuel element simulator. A series of experiments were carried out by supplying power to outer, middle and center rods of 19 pin fuel simulator in ratio of 1.4:1.1:1. The temperature at upper periphery of pressure tube (PT) was slightly higher than at bottom due to increase in local equivalent thermal conductivity from top to bottom of PT. To simulate fully voided conditions PT was pressurized at 2.0 MPa pressure with 17.5 kW power injection. Ballooning initiated from center and then propagates towards the ends and hence axial temperature difference has been observed along the length of PT. For asymmetric heating, upper eight rods of fuel simulator were activated and temperature difference up-to 250 °C has been observed from top to bottom periphery of PT. Such situation creates steep circumferential temperature gradient over PT and could lead to breaching of PT under high pressure.

  10. Smooth muscle-like tissue constructs with circumferentially oriented cells formed by the cell fiber technology.

    Directory of Open Access Journals (Sweden)

    Amy Y Hsiao

    Full Text Available The proper functioning of many organs and tissues containing smooth muscles greatly depends on the intricate organization of the smooth muscle cells oriented in appropriate directions. Consequently controlling the cellular orientation in three-dimensional (3D cellular constructs is an important issue in engineering tissues of smooth muscles. However, the ability to precisely control the cellular orientation at the microscale cannot be achieved by various commonly used 3D tissue engineering building blocks such as spheroids. This paper presents the formation of coiled spring-shaped 3D cellular constructs containing circumferentially oriented smooth muscle-like cells differentiated from dedifferentiated fat (DFAT cells. By using the cell fiber technology, DFAT cells suspended in a mixture of extracellular proteins possessing an optimized stiffness were encapsulated in the core region of alginate shell microfibers and uniformly aligned to the longitudinal direction. Upon differentiation induction to the smooth muscle lineage, DFAT cell fibers self-assembled to coiled spring structures where the cells became circumferentially oriented. By changing the initial core-shell microfiber diameter, we demonstrated that the spring pitch and diameter could be controlled. 21 days after differentiation induction, the cell fibers contained high percentages of ASMA-positive and calponin-positive cells. Our technology to create these smooth muscle-like spring constructs enabled precise control of cellular alignment and orientation in 3D. These constructs can further serve as tissue engineering building blocks for larger organs and cellular implants used in clinical treatments.

  11. Smooth muscle-like tissue constructs with circumferentially oriented cells formed by the cell fiber technology.

    Science.gov (United States)

    Hsiao, Amy Y; Okitsu, Teru; Onoe, Hiroaki; Kiyosawa, Mahiro; Teramae, Hiroki; Iwanaga, Shintaroh; Kazama, Tomohiko; Matsumoto, Taro; Takeuchi, Shoji

    2015-01-01

    The proper functioning of many organs and tissues containing smooth muscles greatly depends on the intricate organization of the smooth muscle cells oriented in appropriate directions. Consequently controlling the cellular orientation in three-dimensional (3D) cellular constructs is an important issue in engineering tissues of smooth muscles. However, the ability to precisely control the cellular orientation at the microscale cannot be achieved by various commonly used 3D tissue engineering building blocks such as spheroids. This paper presents the formation of coiled spring-shaped 3D cellular constructs containing circumferentially oriented smooth muscle-like cells differentiated from dedifferentiated fat (DFAT) cells. By using the cell fiber technology, DFAT cells suspended in a mixture of extracellular proteins possessing an optimized stiffness were encapsulated in the core region of alginate shell microfibers and uniformly aligned to the longitudinal direction. Upon differentiation induction to the smooth muscle lineage, DFAT cell fibers self-assembled to coiled spring structures where the cells became circumferentially oriented. By changing the initial core-shell microfiber diameter, we demonstrated that the spring pitch and diameter could be controlled. 21 days after differentiation induction, the cell fibers contained high percentages of ASMA-positive and calponin-positive cells. Our technology to create these smooth muscle-like spring constructs enabled precise control of cellular alignment and orientation in 3D. These constructs can further serve as tissue engineering building blocks for larger organs and cellular implants used in clinical treatments.

  12. Nonlinear Local Bending Response and Bulging Factors for Longitudinal and Circumferential Cracks in Pressurized Cylindrical Shells

    Science.gov (United States)

    Young, Richard D.; Rose, Cheryl A.; Starnes, James H., Jr.

    2000-01-01

    Results of a geometrically nonlinear finite element parametric study to determine curvature correction factors or bulging factors that account for increased stresses due to curvature for longitudinal and circumferential cracks in unstiffened pressurized cylindrical shells are presented. Geometric parameters varied in the study include the shell radius, the shell wall thickness, and the crack length. The major results are presented in the form of contour plots of the bulging factor as a function of two nondimensional parameters: the shell curvature parameter, lambda, which is a function of the shell geometry, Poisson's ratio, and the crack length; and a loading parameter, eta, which is a function of the shell geometry, material properties, and the applied internal pressure. These plots identify the ranges of the shell curvature and loading parameters for which the effects of geometric nonlinearity are significant. Simple empirical expressions for the bulging factor are then derived from the numerical results and shown to predict accurately the nonlinear response of shells with longitudinal and circumferential cracks. The numerical results are also compared with analytical solutions based on linear shallow shell theory for thin shells, and with some other semi-empirical solutions from the literature, and limitations on the use of these other expressions are suggested.

  13. Effects of inlet circumferential fluctuation on the sweep aerodynamic performance of axial fans/compressors

    Science.gov (United States)

    Gui, Xingmin; Zhu, Fang; Wan, Ke; Jin, Donghai

    2013-10-01

    Swept blades have been widely used in the transonic fan/compressor of aircraft engines with the aids of 3D CFD simulation since the design concept of controlling the shock structure was firstly proposed and successfully tested by Dr. Wennerstrom in the 1980s. However, some disadvantage phenomenon has also been induced by excessively 3D blade geometries on the structure stress insufficiency, vibration and reliability. Much confusion in the procedure of design practice leading us to recognize a new view on the flow mechanism of sweep aerodynamical induction: the new radial equilibrium established by the influence of inlet circumferential fluctuation (CF) changes the inlet flows of blading and induces the performance modification of axial fans/compressors blade. The view is verified by simplified models through numerical simulation and circumferentially averaged analysis in the present paper. The results show that the CF source items which originate from design parameters, such as the spanwise distributions of the loading and blading geometries, contribute to the changing of averaged incidence spanwise distribution, and further more affect the performance of axial fans/compressors with swept blades.

  14. Effects of circumferential rigid wrist orthoses in rehabilitation of patients with radius fracture at typical site

    Directory of Open Access Journals (Sweden)

    Đurović Aleksandar

    2005-01-01

    Full Text Available Background. The use of orthoses is a questionable rehabilitation method for patients with the distal radius fracture at typical site. The aim of this study was to compare the effects of the rehabilitation on patients with radius fracture at the typical site, who wore circumferential static wrist orthoses, with those who did not wear them. Methods. Thirty patients were divided into 3 equal groups, 2 experimental groups, and 1 control group. The patients in the experimental groups were given the rehabilitation program of wearing serially manufactured (off-the-shelf, as well as custom-fit orthoses. Those in the control group did not wear wrist orthoses. Evaluation parameters were pain, edema, the range of the wrist motion, the quality of cylindrical, spherical, and pinch-spherical grasp, the strength of pinch and hand grasp, and patient's assessment of the effects of rehabilitation. Results. No significant difference in the effects of rehabilitation on the patients in experimental groups as opposed to control group was found. Patients in the first experimental group, and in control group were more satisfied with the effects of rehabilitation, as opposed to the patients in the second experimental group (p<0,05. Conclusion. The effects of circumferential static wrist orthoses in the rehabilitation of patients with distal radius fracture at the typical site were not clinically significant. There was no significant difference between the custom and off-the-shelf orthoses.

  15. COMPUTATIONAL AND EXPERIMENTAL STUDY ON TIP LEAKAGE VORTEX OF CIRCUMFERENTIAL SKEWED BLADES

    Institute of Scientific and Technical Information of China (English)

    LI Yang; OUYANG Hua; DU Zhaohui

    2007-01-01

    In the steady operation condition, the experiments and the numerical simulations are used to investigate the tip leakage flow fields in three low pressure axial flow fans with three kinds of circumferential skewed rotors, including the radial rotor, the forward-skewed rotor and the backward-skewed rotor. The three-dimensional viscous flow fields of the fans are computed. In the experiments, the two-dimensional plane particle image velocimetry (PIV) system is used to measure the flow fields in the tip region of three different pitchwise positions of each fan. The results show that the computational results agree well with the experimental data in the flow field of the tip region of each fan. The tip leakage vortex core segments based on method of the eigenmode analysis can display clearly some characteristics of the tip leakage vortex, such as the origination position of tip leakage vortex, the development of vortex strength, and so on. Compared with the radial rotor, the other two skewed rotors can increase the stability of the tip leakage vortex and the increment in the forward-skewed rotor is more than that in the backward-skewed one. Among the tip leakage vortices of the three rotors, the velocity of the vortex in the forward-skewed rotor is the highest in the circumferential direction and the lowest in the axial direction.

  16. Reduction of longitudinal axial residual stresses in near-root region of circumferential joint of steam pipeline in technological way

    Directory of Open Access Journals (Sweden)

    V. M. Prokhorenko

    2013-10-01

    Full Text Available The paper proposes a variant for solving the problem of reduction of longitudinal residual stresses in near-root region of a circumferential welded joint of section of steam pipeline by FEM simulation of the stress-strain state of repaired section of a circumferential weld in the zone of lack of root penetration on a thin-wall shell of 89 mm diameter and 6 mm wall thickness from steel 20. The result of solving the problem is total distribution of stresses and residual plastic deformations in the repaired zone.

  17. Tip clearance flow interaction with circumferential groove casing treatment in a transonic axial compressor

    Science.gov (United States)

    Ross, Mark Hamilton

    Experimental and computational studies were conducted to study the role of the tip leakage flow in axial compressor stall and the relationship between the tip clearance flow flow field and surge margin extension from circumferential groove casing treatment. The CFD results were used to identify the existence of an interface between the approach ow and the tip-leakage flow. The experiments used a surface streaking visualization method to identify the time-averaged location of this interface as a line of zero axial shear stress at the casing. The axial position of this line, denoted xzs, moved upstream with decreasing ow coefficient in both the experiments and computations. The line was consistently located at the rotor leading edge plane at the stalling flow coefficient, regardless of in flow boundary condition. These results were successfully modeled using a control volume approach that balanced the reverse axial momentum ux of the tip-leakage flow with the momentum flux of the approach fluid. Non-uniform tip clearance measurements demonstrated that movement of the interface upstream of the rotor leading edge plane leads to the generation of short length scale rotating disturbances. Therefore, stall was interpreted as a critical point in the momentum flux balance of the approach ow and the reverse axial momentum flux of the tip-leakage flow. Experimental measurements of surge margin extension from seven CGCT configurations with a fixed groove geometry demonstrated that the contribution of individual grooves in a multi-groove casing to surge margin extension is an (a) additive and (b) linear function of the smooth wall tip clearance axial momentum ux at the location of a each groove. Extending the axial momentum model to include the in uence of a CGCT showed that circumferential grooves reduce the tip leakage flow axial momentum through radial transport. The equivalent force due to a circumferential groove was demonstrated to be related to the smooth wall tip

  18. Propagation of S-polarized surface polaritons circumferentially around a locally cylindrical surface

    Energy Technology Data Exchange (ETDEWEB)

    Polanco, J. [Department of Physics, University of Texas, El Paso, TX 79968 (United States); Fitzgerald, R.M., E-mail: rfitzgerald@utep.edu [Department of Physics, University of Texas, El Paso, TX 79968 (United States); Maradudin, A.A. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States)

    2012-04-02

    The dispersion relation is derived and solved for s-polarized surface polaritons propagating circumferentially around a portion of a cylindrical interface between vacuum and an isotropic dielectric. In the case that the dielectric is convex toward the vacuum these modes are found to be radiative, and consequently are attenuated as they propagate on the cylindrical surface. When the dielectric is concave toward the vacuum the resulting surface polaritons are nonradiative and propagate unattenuated on the cylinder. Such modes do not exist in the case of a planar interface between a homogeneous isotropic dielectric and vacuum. -- Highlights: ► New surface wave. ► Many-branched dispersion curve. ► More nodes in fields as frequency grows.

  19. Crack shape developments and leak rates for circumferential complex-cracked pipes

    Energy Technology Data Exchange (ETDEWEB)

    Brickstad, B.; Bergman, M. [SAQ Inspection Ltd., Stockholm (Sweden)

    1997-04-01

    A computerized procedure has been developed that predicts the growth of an initial circumferential surface crack through a pipe and further on to failure. The crack growth mechanism can either be fatigue or stress corrosion. Consideration is taken to complex crack shapes and for the through-wall cracks, crack opening areas and leak rates are also calculated. The procedure is based on a large number of three-dimensional finite element calculations of cracked pipes. The results from these calculations are stored in a database from which the PC-program, denoted LBBPIPE, reads all necessary information. In this paper, a sensitivity analysis is presented for cracked pipes subjected to both stress corrosion and vibration fatigue.

  20. Circumferential resonance modes of solid elastic cylinders excited by obliquely incident acoustic waves.

    Science.gov (United States)

    Fan, Ying; Honarvar, Farhang; Sinclair, Anthony N; Jafari, Mohammad-Reza

    2003-01-01

    When an immersed solid elastic cylinder is insonified by an obliquely incident plane acoustic wave, some of the resonance modes of the cylinder are excited. These modes are directly related to the incidence angle of the insonifying wave. In this paper, the circumferential resonance modes of such immersed elastic cylinders are studied over a large range of incidence angles and frequencies and physical explanations are presented for singular features of the frequency-incidence angle plots. These features include the pairing of one axially guided mode with each transverse whispering gallery mode, the appearance of an anomalous pseudo-Rayleigh in the cylinder at incidence angles greater than the Rayleigh angle, and distortional effects of the longitudinal whispering gallery modes on the entire resonance spectrum of the cylinder. The physical explanations are derived from Resonance Scattering Theory (RST), which is employed to determine the interior displacement field of the cylinder and its dependence on insonification angle.

  1. Amniotic membrane grafts for the prevention of esophageal stricture after circumferential endoscopic submucosal dissection.

    Directory of Open Access Journals (Sweden)

    Maximilien Barret

    Full Text Available The prevention of esophageal strictures following circumferential mucosal resection remains a major clinical challenge. Human amniotic membrane (AM is an easily available material, which is widely used in ophthalmology due to its wound healing, anti-inflammatory and anti-fibrotic properties. We studied the effect of AM grafts in the prevention of esophageal stricture after endoscopic submucosal dissection (ESD in a swine model.In this prospective, randomized controlled trial, 20 swine underwent a 5 cm-long circumferential ESD of the lower esophagus. In the AM Group (n = 10, amniotic membrane grafts were placed on esophageal stents; a subgroup of 5 swine (AM 1 group was sacrificed on day 14, whereas the other 5 animals (AM 2 group were kept alive. The esophageal stent (ES group (n = 5 had ES placement alone after ESD. Another 5 animals served as a control group with only ESD.The prevalence of symptomatic strictures at day 14 was significantly reduced in the AM group and ES groups vs. the control group (33%, 40% and 100%, respectively, p = 0.03; mean esophageal diameter was 5.8±3.6 mm, 6.8±3.3 mm, and 2.6±1.7 mm for AM, ES, and control groups, respectively. Median (range esophageal fibrosis thickness was 0.87 mm (0.78-1.72, 1.19 mm (0.28-1.95, and 1.65 mm (0.7-1.79 for AM 1, ES, and control groups, respectively. All animals had developed esophageal strictures by day 35.The anti-fibrotic effect of AM on esophageal wound healing after ESD delayed the development of esophageal stricture in our model. However, this benefit was of limited duration in the conditions of our study.

  2. Quantitative lymphoscintigraphy in post-mastectomy lymphedema: correlation with circumferential measurements

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Joon Young; Lee, Kyung Han; Kim, Sang Eun; Kim, Byung Tae; Hwang, Jee Hea; Lee, Byung Boong [Samsung Medical Center, Seoul (Korea, Republic of)

    1997-07-01

    An objective measure for the severity and progression is important for the management of lymphedema. To evaluate the usefulness of lympho-scintigraphy in this regard, we compared various quantitative indices from upper extremity lymphoscintigraphy with circumferential measurements, before and after physiotheraphy. Upper extremity lymphoscintigraphy was performed in 38 patients with unilateral postmastectomy lymphedema. Tc-99m antimony sulfide colloid (37 MBq) was injected s.c. into the second and third interdigital spaces. The injection sites were imaged immediately after injection. After standardized exercise for 15 min, upper extremity images were acquired 30 min, 1 hr and 2 hr after injection. The clearance of the injection site (CL), and % uptake in regional lymph nodes (%LN) and soft tissue of the extremity (i.e., the degree of dermal backflow) (%EXT) compared to the initial injection site were calculated. Circumference of each extremity was measured at 7 levels; the severity of lymphedema was expressed as the percentage difference of total circumferential difference (TCD) between healthy and edematous extremities compared to the total circumference of healthy extremity (%TCD). In 19 patients who received physiotherapy, the therapeutic effect was measured by % decrease of TCD (%DTCD) before and after therapy (Raines. et al., 1977). The quantitative indices calculated in the image at 2 hr p.i. had better correlation with either %TCD or %DTCD than those from earlier images (Table). The CL, %LN and %EXT of edematous extremity had a significant correlation with TCD. The %EXT was correlated best with either TCD or %DTCD. The results suggest that the %EXT which corresponds to the degree of dermal backflow may be a simple and useful quantitative index for evaluating the severity and progression in lymphedema and predicting the effect of therapy.

  3. Development of a used fuel cladding damage model incorporating circumferential and radial hydride responses

    Science.gov (United States)

    Chen, Qiushi; Ostien, Jakob T.; Hansen, Glen

    2014-04-01

    At the completion of the fuel drying process, used fuel Zry4 cladding typically exhibits a significant population of δ-hydride inclusions. These inclusions are in the form of small platelets that are generally oriented both circumferentially and radially within the cladding material. There is concern that radially-oriented hydride inclusions may weaken the cladding material and lead to issues during used fuel storage and transportation processes. A high fidelity model of the mechanical behavior of hydrides has utility in both designing fuel cladding to be more resistant to this hydride-induced weakening and also in suggesting modifications to drying, storage, and transport operations to reduce the impact of hydride formation and/or the avoidance of loading scenarios that could overly stress the radial inclusions. We develop a mechanical model for the Zry4-hydride system that, given a particular morphology of hydride inclusions, allows the calculation of the response of the hydrided cladding under various loading scenarios. The model treats the Zry4 matrix material as J2 elastoplastic, and treats the hydrides as platelets oriented in predefined directions (e.g., circumferentially and radially). The model is hosted by the Albany analysis framework, where a finite element approximation of the weak form of the cladding boundary value problem is solved using a preconditioned Newton-Krylov approach. Instead of forming the required system Jacobian operator directly or approximating its action with a differencing operation, Albany leverages the Trilinos Sacado package to form the Jacobian via automatic differentiation. We present results that describe the performance of the model in comparison with as-fabricated Zry4 as well as HB Robinson fuel cladding. Further, we also present performance results that demonstrate the efficacy of the overall solution method employed to host the model.

  4. Development of a used fuel cladding damage model incorporating circumferential and radial hydride responses

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Qiushi, E-mail: qiushi@clemson.edu [Glenn Department of Civil Engineering, Clemson University, Clemson, SC 29634 (United States); Ostien, Jakob T., E-mail: jtostie@sandia.gov [Mechanics of Materials Dept. 8256, Sandia National Laboratories, P.O. Box 969, Livermore, CA 94551-0969 (United States); Hansen, Glen, E-mail: gahanse@sandia.gov [Computational Multiphysics Dept. 1443, Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87185-1321 (United States)

    2014-04-01

    At the completion of the fuel drying process, used fuel Zry4 cladding typically exhibits a significant population of δ-hydride inclusions. These inclusions are in the form of small platelets that are generally oriented both circumferentially and radially within the cladding material. There is concern that radially-oriented hydride inclusions may weaken the cladding material and lead to issues during used fuel storage and transportation processes. A high fidelity model of the mechanical behavior of hydrides has utility in both designing fuel cladding to be more resistant to this hydride-induced weakening and also in suggesting modifications to drying, storage, and transport operations to reduce the impact of hydride formation and/or the avoidance of loading scenarios that could overly stress the radial inclusions. We develop a mechanical model for the Zry4-hydride system that, given a particular morphology of hydride inclusions, allows the calculation of the response of the hydrided cladding under various loading scenarios. The model treats the Zry4 matrix material as J{sub 2} elastoplastic, and treats the hydrides as platelets oriented in predefined directions (e.g., circumferentially and radially). The model is hosted by the Albany analysis framework, where a finite element approximation of the weak form of the cladding boundary value problem is solved using a preconditioned Newton–Krylov approach. Instead of forming the required system Jacobian operator directly or approximating its action with a differencing operation, Albany leverages the Trilinos Sacado package to form the Jacobian via automatic differentiation. We present results that describe the performance of the model in comparison with as-fabricated Zry4 as well as HB Robinson fuel cladding. Further, we also present performance results that demonstrate the efficacy of the overall solution method employed to host the model.

  5. Circumferential electrocautery of the patella in primary total knee replacement without patellar replacement: a meta-analysis and systematic review

    Science.gov (United States)

    Fan, Lihong; Ge, Zhaogang; Zhang, Chen; Li, Jia; Yu, Zefeng; Dang, Xiaoqian; Wang, Kunzheng

    2015-03-01

    The purpose of this meta-analysis and systematic review was to identify and assess whether circumferential electrocautery is useful for improving outcomes after primary total knee replacement(TKR). We searched MEDLINE, EMBASE, PubMed, SpringerLink, Web of Knowledge, OVID CINAHL, OVID EBM and Google Scholar and included articles published through January 2014. A total of 6 articles met the inclusion criteria. Of the 776 cases included in the analysis, 388 cases involved patellar denervation, and 388 cases were designated as the control group. The meta-analysis revealed no significant difference in the incidence of anterior knee pain (AKP, p = 0.18) or in the visual analogue scale score (VAS, p = 0.23) between the two groups. In addition, AKSS Function Score indicated no significant difference between the two groups (p = 0.28). However, the OKS (p = 0.02), patellar score (p = 0.01), AKSS-Knee Score (p = 0.004), range of motion (ROM, p < 0.0001) and WOMAC Score (p = 0.0003) indicated that circumpatellarelectrocautery improved clinical outcomes compared with non-electrocautery. The results indicate that circumferential electrocautery of the patella does not significantly improve AKP compared with non-electrocautery techniques but that circumferential electrocautery significantly improves patients' knee function after surgery. Therefore, we believe that circumferential electrocautery is beneficial to the outcome of primary TKR surgery without patellar replacement.

  6. Initial experience with circumferential pulmonary vein ablation guided by fusion of magnetic resonance imaging with three-dimensional electroanatomic mapping

    Institute of Scientific and Technical Information of China (English)

    TANG Kai; MA Jian; MA Fu-sheng; JlA Yu-he; ZHANG Shu

    2006-01-01

    @@ Catheter ablation for the treatment of atrial fibrillation (AF) has been a focal target of electrophysiological study in recent years. Up to date,circumferential pulmonary vein ablation (CPVA)guided by three-dimensional (3-D) electroanatomic mapping (Carto, USA) has been one of the most favourable procedures for the treatment of AF.

  7. Burn-out, Circumferential Film Flow Distribution and Pressure Drop for an Eccentric Annulus with Heated Rod

    DEFF Research Database (Denmark)

    Andersen, P. S.; Jensen, A.; Mannov, G.

    1974-01-01

    Measurements of (1) burn-out, (2) circumferential film flow distribution, and (3) pressure drop in a 17 × 27.2 × 3500 mm concentric and eccentric annulus geometry are presented. The eccentric displacement was varied between 0 and 3 mm. The working fluid was water. Burn-out curves at 70 bar...... flow variation on burn-out is discussed....

  8. Modeling and numerical investigation of the inlet circumferential fluctuations of swept and bowed blades

    Science.gov (United States)

    Tang, Mingzhi; Jin, Donghai; Gui, Xingmin

    2017-02-01

    The circumferential fluctuation (CF) source terms induced by the inviscid blade force can affect the inlet distribution of flow parameters and radial equilibrium of swept and bowed blades. However, these phenomena cannot be adequately described by throughflow methods based on the axisymmetric assumption. A transport model for the CF stresses is proposed and correlated to the distribution of circulation to reflect the effect of the inviscid blade force. To investigate the effect of the inlet CFs on swept and bowed blades, the model is integrated into a throughflow model and applied to a series of cascades with different sweep and bow angles. For swept cascades, the CF source terms change the distributions of incidence angles, as well as the radial equilibrium at the inlet of the blade passage. And the influence is enhanced as the absolute value of the sweep angle increases. For bowed cascades, the distributions of incidence angles are also altered. For both cases, the model can offer a good prediction of the inlet CF source terms, and prove to exert a better prediction of blade design key parameters such as flow angles.

  9. The Prognostic Value of Circumferential Resection Margin Involvement in Patients with Extraperitoneal Rectal Cancer.

    Science.gov (United States)

    Shin, Dong Woo; Shin, Jin Yong; Oh, Sung Jin; Park, Jong Kwon; Yu, Hyeon; Ahn, Min Sung; Bae, Ki Beom; Hong, Kwan Hee; Ji, Yong Il

    2016-04-01

    The prognostic influence of circumferential resection margin (CRM) status in extraperitoneal rectal cancer probably differs from that of intraperitoneal rectal cancer because of its different anatomical and biological behaviors. However, previous reports have not provided the data focused on extraperitoneal rectal cancer. Therefore, the aim of this study was to examine the prognostic significance of the CRM status in patients with extraperitoneal rectal cancer. From January 2005 to December 2008, 248 patients were treated for extraperitoneal rectal cancer and enrolled in a prospectively collected database. Extraperitoneal rectal cancer was defined based on tumors located below the anterior peritoneal reflection, as determined intraoperatively by a surgeon. Cox model was used for multivariate analysis to examine risk factors of recurrence and mortality in the 248 patients, and multivariate logistic regression analysis was performed to identify predictors of recurrence and mortality in 135 patients with T3 rectal cancer. CRM involvement for extraperitoneal rectal cancer was present in 29 (11.7%) of the 248 patients, and was the identified predictor of local recurrence, overall recurrence, and death by multivariate Cox analysis. In the 135 patients with T3 cancer, CRM involvement was found to be associated with higher probability of local recurrence and mortality. In extraperitoneal rectal cancer, CRM involvement is an independent risk factor of recurrence and survival. Based on the results of the present study, it seems that CRM involvement in extraperitoneal rectal cancer is considered an indicator for (neo)adjuvant therapy rather than conventional TN status.

  10. Performance comparison for oil-water heat transfer of circumferential overlap trisection helical baffle heat exchanger

    Institute of Scientific and Technical Information of China (English)

    王伟晗; 程道来; 刘涛; 刘颖昊

    2016-01-01

    The performance tests were conducted on oil–water heat transfer in circumferential overlap trisection helical baffle heat exchangers with incline angles of 12°, 16°, 20°, 24° and 28°, and compared with a segmental baffle heat exchanger. The results show that the shell side heat transfer coefficientho and pressure dropΔpo both increase while the comprehensive indexho/Δpo decreases with the increase of the mass flow rate of all schemes. And the shell side heat transfer coefficient, pressure drop and the comprehensive indexho/Δpo decrease with the increase of the baffle incline angle at a certain mass flow rate. The average values of shell side heat transfer coefficient and the comprehensive indexho/Δpo of the 12° helical baffled scheme are above 50% higher than those of the segmental one correspondingly, while the pressure drop value is very close and the ratios of the average values are about 1.664 and 1.596, respectively. The shell-side Nusselt numberNuo and the comprehensive index Nuo·Euzo−1 increase with the increase of Reynolds number of the shell side axial in all schemes, and the results also demonstrate that the small incline angled helical scheme has better comprehensive performance.

  11. Feasibility of radial and circumferential strain analysis using 2D speckle tracking echocardiography in cats

    Science.gov (United States)

    TAKANO, Hiroshi; ISOGAI, Tomomi; AOKI, Takuma; WAKAO, Yoshito; FUJII, Yoko

    2014-01-01

    The purpose of the present study is to investigate the feasibility of strain analysis using speckle tracking echocardiography (STE) in cats and to evaluate STE variables in cats with hypertrophic cardiomyopathy (HCM). Sixteen clinically healthy cats and 17 cats with HCM were used. Radial and circumferential strain and strain rate variables in healthy cats were measured using STE to assess the feasibility. Comparisons of global strain and strain variables between healthy cats and cats with HCM were performed. Segmental assessments of left ventricle (LV) wall for strain and strain rate variables in cats with HCM were also performed. As a result, technically adequate images were obtained in 97.6% of the segments for STE analysis. Sedation using buprenorphine and acepromazine did not affect any global strain nor strain rate variable. In LV segments of cats with HCM, reduced segmental radial strain and strain rate variables had significantly related with segmental LV hypertrophy. It is concluded that STE analysis using short axis images of LV appeared to be clinically feasible in cats, having the possibility to be useful for detecting myocardial dysfunctions in cats with diseased heart. PMID:25373881

  12. Vascular Repair by Circumferential Cell Therapy Using Magnetic Nanoparticles and Tailored Magnets.

    Science.gov (United States)

    Vosen, Sarah; Rieck, Sarah; Heidsieck, Alexandra; Mykhaylyk, Olga; Zimmermann, Katrin; Bloch, Wilhelm; Eberbeck, Dietmar; Plank, Christian; Gleich, Bernhard; Pfeifer, Alexander; Fleischmann, Bernd K; Wenzel, Daniela

    2016-01-26

    Cardiovascular disease is often caused by endothelial cell (EC) dysfunction and atherosclerotic plaque formation at predilection sites. Also surgical procedures of plaque removal cause irreversible damage to the EC layer, inducing impairment of vascular function and restenosis. In the current study we have examined a potentially curative approach by radially symmetric re-endothelialization of vessels after their mechanical denudation. For this purpose a combination of nanotechnology with gene and cell therapy was applied to site-specifically re-endothelialize and restore vascular function. We have used complexes of lentiviral vectors and magnetic nanoparticles (MNPs) to overexpress the vasoprotective gene endothelial nitric oxide synthase (eNOS) in ECs. The MNP-loaded and eNOS-overexpressing cells were magnetic, and by magnetic fields they could be positioned at the vascular wall in a radially symmetric fashion even under flow conditions. We demonstrate that the treated vessels displayed enhanced eNOS expression and activity. Moreover, isometric force measurements revealed that EC replacement with eNOS-overexpressing cells restored endothelial function after vascular injury in eNOS(-/-) mice ex and in vivo. Thus, the combination of MNP-based gene and cell therapy with custom-made magnetic fields enables circumferential re-endothelialization of vessels and improvement of vascular function.

  13. Interactions of a propeller with a stator-induced circumferentially varying flow

    Energy Technology Data Exchange (ETDEWEB)

    Farnsworth, John [Rensselaer Polytechnic Institute, Mechanical Aerospace and Nuclear Engineering, Troy, NY (United States); US Air Force Academy, Department of Aeronautics, Colorado Springs, CO (United States); Amitay, Michael [Rensselaer Polytechnic Institute, Mechanical Aerospace and Nuclear Engineering, Troy, NY (United States); Rensselaer Polytechnic Institute, Center for Flow Physics and Control (CeFPaC), Troy, NY (United States); Beal, David; Huyer, Stephen A. [Naval Undersea Warfare Center, Division, Vehicle Dynamics and Signature Control, Newport, RI (United States)

    2012-02-15

    The interactions of a circumferentially varying stator cascade and a downstream fixed pitch propeller were investigated experimentally. The global performance of the components and the coupled system were systematically investigated through force and moment measurements on the propulsor model in a water tunnel. In addition, the wake of the cyclic stator cascade with and without the propeller was investigated downstream from a propulsor model using the Stereoscopic PIV technique. A cyclic distribution of the stators' deflections resulted in non-axisymmetric distributions of the flow field downstream of the stator array. The stator distribution alone produced a significant side force that increased linearly with stator pitch amplitude. When a propeller was incorporated downstream from the cyclic cascade, the side force from the stator cascade was reduced, but a small normal force and pitching moment were created. The generation of these secondary forces and moments can be related to the redistribution of the tangential flow from the cyclic cascade into the axial direction by the retreating and advancing blade states of the fixed pitch propeller. (orig.)

  14. Leak before break behaviour of austenitic and ferritic pipes containing circumferential defects

    Energy Technology Data Exchange (ETDEWEB)

    Stadtmueller, W.; Sturm, D.

    1997-04-01

    Several research projects carried out at MPA Stuttgart to investigate the Leak-before-Break (LBB) behavior of safety relevant pressure bearing components are summarized. Results presented relate to pipes containing circumferential defects subjected to internal pressure and external bending loading. An overview of the experimentally determined results for ferritic components is presented. For components containing postulated or actual defects, the dependence of the critical loading limit on the defect size is shown in the form of LBB curves. These are determined experimentally and/or by calculation for through-wall slits, and represent the boundary curve between leakage and massive fracture. For surface defects and a given bending moment and internal pressure, no fracture will occur if the length at leakage remains smaller than the critical defect length given by the LBB curve for through-wall defects. The predictive capability of engineering calculational methods are presented by way of example. The investigation programs currently underway, testing techniques, and initial results are outlined.

  15. Error Modeling and Compensation of Circular Motion on a New Circumferential Drilling System

    Directory of Open Access Journals (Sweden)

    Qiang Fang

    2015-01-01

    Full Text Available A new flexible circumferential drilling system is proposed to drill on the fuselage docking area. To analyze the influence of the circular motion error to the drilling accuracy, the nominal forward kinematic model is derived using Denavit-Hartenberg (D-H method and this model is further developed to model the kinematic errors caused by circular positioning error and synchronization error using homogeneous transformation matrices (HTM. A laser tracker is utilized to measure the circular motion error of the two measurement points at both sides. A circular motion compensation experiment is implemented according to the calculated positioning error and synchronization error. Experimental results show that the positioning error and synchronization error were reduced by 65.0% and 58.8%, respectively, due to the adopted compensation, and therefore the circular motion accuracy is substantially improved. Finally, position errors of the two measurement points are analyzed to have little influence on the measurement result and the validity of the proposed compensation method is proved.

  16. Circumferential 2D-strain imaging for the prediction of long term response to cardiac resynchronization therapy

    Directory of Open Access Journals (Sweden)

    Baumann Gert

    2008-06-01

    Full Text Available Abstract Background Cardiac Resynchronization Therapy (CRT leads to hemodynamic and clinical improvement in heart failure patients. The established methods to evaluate myocardial asynchrony analyze longitudinal and radial myocardial function. This study evaluates the new method of circumferential 2D-strain imaging in the prediction of the long-term response to CRT. Methods and results 38 heart failure patients (NYHA II-III, QRS > 120 ms, LVEF Conclusion There is a significant decrease in the circumferential 2D-strain derived delays after CRT, indicating that resynchronization induces improvement in all three dimensions of myocardial contraction. However, the resulting predictive values of 2D strain delays are not superior to longitudinal and radial 2D-strain or TDI delays.

  17. Comparison of treatment for 153 cases of circumferential facial paralysis by low-power laser and galvan acupuncture

    Science.gov (United States)

    Li, Hai-Ling; Zhuo, Qing-shan

    1993-03-01

    Seventy-six patients were treated by low power He-Ne laser irradiation on Yangbai, Sibai, and other related acupoints. The other 77 cases were treated by Galvan-acupuncture with infrared radiation on the same acupoints. There was little difference between the therapeutic effects of these two groups (P > 0.05). However, the laser group had a much shorter treatment time than the other group. According to the theory of traditional Chinese medicine, circumferential facial paralysis is caused by exposure to cold which blocks the channel of vital energy resulting in the damage of bodily function. Acupuncture and moxibustion on certain acupoints can warm up the channels and remove the stasis allowing vital energy to pass through their passages to regulate bodily functions. Laser can do the same effectively with much less time. The laser therapy also features painlessness, safeness, and is free of bacteria. Circumferential facial paralysis is a common disease, which is clinically treated by acupuncture with reliable results. However, acupuncture is not fit for children who are not cooperative and those patients who are afraid of the pain accompanied with acupuncture. So we applied low power laser irradiation in the treatment of circumferential facial paralysis starting in 1985. The results were favorable. And the treatment time was shortened. The treatment procedures are reported.

  18. SYNERGY OF WALL SHEAR STRESS AND CIRCUMFERENTIAL STRESS IN STRAIGHT ARTERIES

    Institute of Scientific and Technical Information of China (English)

    QIN Kai-rong; XU Zhe; WU Hao; JIANG Zong-lai; LIU Zhao-rong

    2005-01-01

    The Wall Shear Stress (WSS) generated by blood flow and Circumferential Stress (CS) driven by blood pressure have been thought to play an important role in blood flow-dependent phenomena such as angiogenesis, vascular remodeling, and atherosgenesis.The WSS and CS in straight arteries were calculated by measuring the blood pressure, center-line velocity, wall thickness, and radius of vessels.The WSS and CS in the time domain were then decomposed into the amplitude and phase in the frequency domain.The CS amplitude to the WSS amplitude ratio (referred as stress amplitude ratio, Zs) and the phase difference between the CS and the WSS (referred as stress phase difference, SPA) in the frequency domain were calculated to characterize the synergy of the CS and WSS.Numerical results demonstrated that the CS is not in phase with the WSS, a time delay in the time domain or a stress phase difference in the frequency domain between the WSS and the CS exists.Theoretical analysis demonstrated that the Zs and SPA are primarily determined by the local factors (blood viscosity, local inertial effects, local geometry, local elasticity) and the input impedance of whole downstream arterial beds.Because the arterial input impedance has been shown to reflect the physiological and pathological states of whole downstream arterial beds, the stress amplitude ratio Zs and stress phase difference SPA would be thought to be the appropriate indices to reflect the effects of states of whole downstream arterial beds on the local blood flow-dependent phenomena such as angiogenesis, vascular remodeling, and atherosgenesis.

  19. Measurement of the circumferential mechanical properties of the umbilical vein: experimental and numerical analyses.

    Science.gov (United States)

    Karimi, Alireza; Navidbakhsh, Mahdi; Rezaee, Taraneh; Hassani, Kamran

    2015-01-01

    Coronary artery disease is responsible for almost 30% of all deaths worldwide. The saphenous vein and umbilical vein (UV) are the most common veins using for treatment as a coronary artery bypass graft (CABG). The mechanical properties of UV belonging to its long-term patency for CABG are very important. However, there is a lack of knowledge on the linear elastic and nonlinear hyperelastic mechanical properties of the UV. In this study, three stress definitions (second Piola-Kichhoff stress, engineering stress and true stress) and four strain definitions (Almansi-Hamel strain, Green-St Venant strain, engineering strain and true strain) are used to determine the elastic modulus, maximum stress and strain of eight human UVs under circumferential loading. The nonlinear mechanical behaviour of the UV is computationally investigated using Mooney-Rivlin hyperelastic model. A numerical finite element analysis is also carried out to simulate the constitutive modelling versus its numerical results. The results show that the Almansi-Hamel strain definition overestimates the elastic modulus while Green-St Venant strain definition underestimates the elastic modulus at different stress definitions. The true stress-true strain definition, which gives more accurate measurements of the tissue's response using the instantaneous values, reveals the Young's modulus and maximum stress of 2.18 and 6.01 MPa, respectively. The Mooney-Rivlin material model is well represented by the nonlinear mechanical behaviour of the UV. The findings of this study could have implications not only for understanding the extension and rupture mechanism of UV but also for interventions and surgeries, including balloon angioplasty, bypass and stenting.

  20. The Interaction between Fluid Wall Shear Stress and Solid Circumferential Strain Affects Endothelial Gene Expression.

    Science.gov (United States)

    Amaya, Ronny; Pierides, Alexis; Tarbell, John M

    2015-01-01

    Endothelial cells lining the walls of blood vessels are exposed simultaneously to wall shear stress (WSS) and circumferential stress (CS) that can be characterized by the temporal phase angle between WSS and CS (stress phase angle - SPA). Regions of the circulation with highly asynchronous hemodynamics (SPA close to -180°) such as coronary arteries are associated with the development of pathological conditions such as atherosclerosis and intimal hyperplasia whereas more synchronous regions (SPA closer to 0°) are spared of disease. The present study evaluates endothelial cell gene expression of 42 atherosclerosis-related genes under asynchronous hemodynamics (SPA=-180 °) and synchronous hemodynamics (SPA=0 °). This study used a novel bioreactor to investigate the cellular response of bovine aortic endothelial cells (BAECS) exposed to a combination of pulsatile WSS and CS at SPA=0 or SPA=-180. Using a PCR array of 42 genes, we determined that BAECS exposed to non-reversing sinusoidal WSS (10±10 dyne/cm2) and CS (4 ± 4%) over a 7 hour testing period displayed 17 genes that were up regulated by SPA = -180 °, most of them pro-atherogenic, including NFκB and other NFκB target genes. The up regulation of NFκB p50/p105 and p65 by SPA =-180° was confirmed by Western blots and immunofluorescence staining demonstrating the nuclear translocation of NFκB p50/p105 and p65. These data suggest that asynchronous hemodynamics (SPA=-180 °) can elicit proatherogenic responses in endothelial cells compared to synchronous hemodynamics without shear stress reversal, indicating that SPA may be an important parameter characterizing arterial susceptibility to disease.

  1. The Interaction between Fluid Wall Shear Stress and Solid Circumferential Strain Affects Endothelial Gene Expression.

    Directory of Open Access Journals (Sweden)

    Ronny Amaya

    Full Text Available Endothelial cells lining the walls of blood vessels are exposed simultaneously to wall shear stress (WSS and circumferential stress (CS that can be characterized by the temporal phase angle between WSS and CS (stress phase angle - SPA. Regions of the circulation with highly asynchronous hemodynamics (SPA close to -180° such as coronary arteries are associated with the development of pathological conditions such as atherosclerosis and intimal hyperplasia whereas more synchronous regions (SPA closer to 0° are spared of disease. The present study evaluates endothelial cell gene expression of 42 atherosclerosis-related genes under asynchronous hemodynamics (SPA=-180 ° and synchronous hemodynamics (SPA=0 °. This study used a novel bioreactor to investigate the cellular response of bovine aortic endothelial cells (BAECS exposed to a combination of pulsatile WSS and CS at SPA=0 or SPA=-180. Using a PCR array of 42 genes, we determined that BAECS exposed to non-reversing sinusoidal WSS (10±10 dyne/cm2 and CS (4 ± 4% over a 7 hour testing period displayed 17 genes that were up regulated by SPA = -180 °, most of them pro-atherogenic, including NFκB and other NFκB target genes. The up regulation of NFκB p50/p105 and p65 by SPA =-180° was confirmed by Western blots and immunofluorescence staining demonstrating the nuclear translocation of NFκB p50/p105 and p65. These data suggest that asynchronous hemodynamics (SPA=-180 ° can elicit proatherogenic responses in endothelial cells compared to synchronous hemodynamics without shear stress reversal, indicating that SPA may be an important parameter characterizing arterial susceptibility to disease.

  2. Single-stage Posterior Spondylectomy,Circumferential Decompression and Reconstruction Using Mesh Cage for Spinal Tumors

    Institute of Scientific and Technical Information of China (English)

    Yong Zhu; Hong Zhao; Giu-xing Qiu; Jian-guo Zhang; Ye Tian; Shu-gang Li; Suo-mao Yuan

    2009-01-01

    Objective To explore the feasibility and clinical results of circumferential decompression and threecolumn reconstruction through single-stage posterior transpedicular approach for spinal tumor treatment.Methods Totally,24 patients with spinal tumor underwent tumor resection and spinal reconstruction through single-stage posterior transpedicular approach.Preoperatively,according to the Frankel classification,12 patients were grade E,9 grade D,and 3 grade C.Anterior column was reconstructed with non-expandable titanium cages.Posterior segmental instrumentation was used to maintain the stability of spine in all cases.Anterior and posterolateral fusion was performed with autograft and allogenic bone.The following data were followed up in these patients:deformity angle,local recurrence,neurological function,and spinal bony fusion.Results The average operating time and blood loss was 5.6 hours and 3 400 ml respectively.No intraoperative and postoperative complications were observed in this group.Postoperatively,21 patients were Frankel grade E,2 grade D,and 1 grade C.Four patients reported significant functional restoration and twenty patients reported complete resolution of pain.At follow-up(range,6-42 months),implant failure or recurrent neurological symptoms was not found.Conclusions The tumor resection and spinal reconstruction through single-stage posterior transpedicular approach is a safe and effective technique for the treatment of spinal tumor.It can fully decompress the neurological structures,correct the kyphosis,and achieve early weight-bearing.This technique can improve life quality for the patients with spinal tumor.

  3. Control of circumferential wall stress and luminal shear stress within intact vascular segments perfused ex vivo.

    Science.gov (United States)

    El-Kurdi, Mohammed S; Vipperman, Jeffrey S; Vorp, David A

    2008-10-01

    Proportional, integral, and derivative (PID) controllers have proven to be robust in controlling many applications, and remain the most widely used control system architecture. The purpose of this work was to use this architecture for designing and tuning two PID controllers. The first was used to control the physiologic arterial circumferential wall stress (CWS) and the second to control the physiologic arterial shear stress (SS) imposed on intact vascular segments that were implanted into an ex vivo vascular perfusion system (EVPS). In order to most accurately control the stresses imposed onto vascular segments perfused ex vivo, analytical models were derived to calculate the CWS and SS. The mid-vein-wall CWS was calculated using the classical Lame solution for thick-walled cylinders in combination with the intraluminal pressure and outer diameter measurements. Similarly, the SS was calculated using the Hagen-Poiseuille equation in combination with the flow rate and outer diameter measurements. Performance of each controller was assessed by calculating the root mean square of the error (RMSE) between the desired and measured process variables. The performance experiments were repeated ten times (N=10) and an average RMSE was reported for each controller. RMSE standard deviations were calculated to demonstrate the reproducibility of the results. Sterile methods were utilized for making blood gas and temperature measurements in order to maintain physiologic levels within the EVPS. Physiologic blood gases (pH, pO(2), and pCO(2)) and temperature within the EVPS were very stable and controlled manually. Blood gas and temperature levels were recorded hourly for several (N=9) 24 h perfusion experiments. RMSE values for CWS control (0.427+/-0.027 KPa) indicated that the system was able to generate a physiologic CWS wave form within 0.5% error of the peak desired CWS over each cardiac cycle. RMSE values for SS control (0.005+/-0.0007 dynescm(2)) indicated that the system

  4. K{sub I}-T estimation for embedded flaws in pipes - Part II: Circumferentially oriented cracks

    Energy Technology Data Exchange (ETDEWEB)

    Qian Xudong, E-mail: cveqx@nus.edu.s [Department of Civil Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576 (Singapore)

    2010-04-15

    This paper, in parallel to the investigation on axially embedded cracks reported in the companion paper, presents a numerical study on the linear-elastic K{sub I} and T-stress values over the front of elliptical cracks circumferentially embedded in the wall of a pipe/cylindrical structure, under a uniform pressure applied on the inner surface of the pipe. The numerical procedure employs the interaction-integral approach to compute the linear-elastic stress-intensity factor (SIF) K{sub I} and T-stress values for embedded cracks with practical sizes at different locations in the wall of the pipe. The parametric study covers a wide range of geometric parameters for embedded cracks in the pipe, including: the wall thickness to the inner radius ratio (t/R{sub i}), the crack depth over the wall thickness ratio (a/t), the crack aspect ratio (a/c) and the ratio of the distance from the centerline of the crack to the outer surface of the pipe over the pipe wall thickness (e{sub M}/t). The parametric investigation identifies a significant effect of the remaining ligament length on both the T-stress and K{sub I} values at the crack-front location (denoted by point O) nearest to the outer surface of the pipe and at the crack-front location (denoted by point I) nearest to the inner surface of the pipe. The numerical investigation establishes the database to derive approximate functions from a nonlinear curve-fitting procedure to predict the T-stress and K{sub I} values at three critical front locations of the circumferentially embedded crack in a pipe: points O, I and M. The proposed T-stress and K{sub I} functions utilize a combined second-order polynomial and a power-law expression, which presents a close agreement with the T-stress and K{sub I} values computed from the very detailed finite element models. The comparison between the circumferentially embedded crack and the axially embedded crack indicates that both the T-stress and K{sub I} values at crack-front points O and

  5. Contribution to the Evaluation of the Circumferentially-Cracked Round Bar for Fracture Toughness Determination of Reactor Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Scibetta, M

    1999-06-01

    The subject of this PhD dissertation is the use of the Circumferentially-Cracked Round Bar (CRB) for fracture toughness measurements. The main advantages of CRB are the relatively small size requirements of the testing specimens, the low cost to machine the specimen, the rotating bending fatigue allowing for easy precracking of specimens, the use of standard tensile test fixture and the axisymmetry of the specimen that avoids time consuming 3D finite element calculations. An in-depth study of the most widely used precracking technique for CRB, namely the rotating bending fatigue, is made.

  6. Quantitative circumferential strain analysis using adenosine triphosphate-stress/rest 3-T tagged magnetic resonance to evaluate regional contractile dysfunction in ischemic heart disease

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Masashi, E-mail: m.nakamura1230@gmail.com [Department of Radiology, Ehime University Graduate School of Medicine, Shitsukawa, Toon-city, Ehime 791-0295 (Japan); Kido, Tomoyuki [Department of Radiology, Saiseikai Matsuyama Hospital, Ehime 791-0295 (Japan); Kido, Teruhito; Tanabe, Yuki; Matsuda, Takuya; Nishiyama, Yoshiko; Miyagawa, Masao; Mochizuki, Teruhito [Department of Radiology, Ehime University Graduate School of Medicine, Shitsukawa, Toon-city, Ehime 791-0295 (Japan)

    2015-08-15

    Highlights: • Infarcted segments could be differentiated from non-ischemic and ischemic segments with high sensitivity and specificity under at rest conditions. • The time-to-peak circumferential strain values in infarcted segments were more significantly delayed than those in non-ischemic and ischemic segments. • Both circumferential strain and circumferential systolic strain rate values under ATP-stress conditions were significantly lower in ischemic segments than in non-ischemic segments. • Subtracting stress and rest circumferential strain had a higher diagnostic capability for ischemia relative to only utilizing rest or ATP-stress circumferential strain values. • A circumferential strain analysis using tagged MR can quantitatively assess contractile dysfunction in ischemic and infarcted myocardium. - Abstract: Purpose: We evaluated whether a quantitative circumferential strain (CS) analysis using adenosine triphosphate (ATP)-stress/rest 3-T tagged magnetic resonance (MR) imaging can depict myocardial ischemia as contractile dysfunction during stress in patients with suspected coronary artery disease (CAD). We evaluated whether it can differentiate between non-ischemia, myocardial ischemia, and infarction. We assessed its diagnostic performance in comparison with ATP-stress myocardial perfusion MR and late gadolinium enhancement (LGE)-MR imaging. Methods: In 38 patients suspected of having CAD, myocardial segments were categorized as non-ischemic (n = 485), ischemic (n = 74), or infarcted (n = 49) from the results of perfusion MR and LGE-MR. The peak negative CS value, peak circumferential systolic strain rate (CSR), and time-to-peak CS were measured in 16 segments. Results: A cutoff value of −12.0% for CS at rest allowed differentiation between infarcted and other segments with a sensitivity of 79%, specificity of 76%, accuracy of 76%, and an area under the curve (AUC) of 0.81. Additionally, a cutoff value of 477.3 ms for time-to-peak CS at rest

  7. Correlation among bioimpedance analysis, sonographic and circumferential measurement in assessment of breast cancer-related arm lymphedema.

    Science.gov (United States)

    Choi, Y H; Seo, K S

    2014-09-01

    New approaches for assessment of lymphedema using ultrasonography (US) have been introduced recently and are reported to be reliable and simple. Ultrasonography provides detailed information about physical properties of the tissue in addition to volume and size. There have been only limited studies comparing bioimpedance analysis (BIA), US, and circumferential measurement (CM), which is considered a standard measurement. The aim of this study was to determine the relationship between US, BIA, and CM. Twenty-eight patients with lymphedema after breast cancer surgery underwent BIA, US, and CM. Impedance, which reflects the amount of extracellular fluid, was measured with 1 kHz frequency in affected and unaffected arms. Circumferences were measured at 10cm proximal and distal to the elbow and a truncated cone method used to calculate estimated volumes for upper arm and forearm. We found that interlimb forearm subcutis thickness differences measured by US were highly correlated with CM measurements and that interlimb upper arm subcutis thickness differences measured by US were moderately correlated with CM measurements and BIA ratios. However, the interlimb ratio of compressibility measured by US showed no or only weak correlation with impedance measurements and circumferential measurements. Our results also show that compressibility measured by US could not be predicted from BIA or CM measurements despite a high degree of concordance among subcutis thickness measured by US, CM, and BIA.

  8. Measurement of the longitudinal and circumferential muscular activity associated with peristalsis using a single fibre grating array

    Science.gov (United States)

    Arkwright, J. W.; Blenman, N. G.; Underhill, I. D.; Maunder, S. A.; Spencer, N. J.; Costa, M.; Brooks, S. J.; Szczesniak, M. M.; Dinning, P. G.

    2010-09-01

    Diagnostic catheters based on fibre Bragg gratings (FBG's) are proving to be highly effective for measurement of the muscular activity associated with peristalsis in the human gut. The primary muscular contractions that generate peristalsis are circumferential in nature; however, it has long been known that there is also a component of longitudinal contractility present, acting in harmony with the circumferential component to improve the overall efficiency of material movement. To date, there have been relatively few reports on the measurement or inference of longitudinal contractions in humans and all have been limited to detection at a single location only. This is due to the lack of a viable recording technique suitable for real-time in-vivo measurement of this type of activity over extended lengths of the gut. We report the detection of longitudinal motion in lengths of excised mammalian colon using an FBG technique that should be viable for similar detection in humans. The longitudinal sensors have been combined with our previously reported FBG pressure sensing elements to form a composite catheter that allows the relative phase between the two components to be detected. The catheter output has been validated using digital video mapping in an ex-vivo animal preparation using lengths of rabbit ileum.

  9. Circumferential fusion is dominant over posterolateral fusion in a long-term perspective: cost-utility evaluation of a randomized controlled trial in severe, chronic low back pain

    DEFF Research Database (Denmark)

    Soegaard, Rikke; Bünger, Cody E; Christiansen, Terkel

    2007-01-01

    STUDY DESIGN: Cost-utility evaluation of a randomized, controlled trial with a 4- to 8-year follow-up. OBJECTIVE: To investigate the incremental cost per quality-adjusted-life-year (QALY) when comparing circumferential fusion to posterolateral fusion in a long-term, societal perspective. SUMMARY...... demonstrated clinical superiority over the posterolateral fusion group in functional outcome (P dominant over posterolateral fusion, that is, for each QALY gained...... the circumferential approach could alter the dominance; however, still the probability of cost-effectiveness was >0.85 given a threshold for willingness to pay of U.S. $50,000 per QALY. CONCLUSION: Circumferential fusion is dominant over instrumented posterolateral fusion, that is, both being significantly cheaper...

  10. Early posterior spinal canal decompression and circumferential reconstruction of rotationally unstable thoracolumbar burst fractures with neurological deficit

    Institute of Scientific and Technical Information of China (English)

    ZHENG Guo-quan; WANG Yan; TANG Pei-fu; ZHANG Yong-gang; ZHANG Xue-song; GUO Yi-zhu; TAO Sheng

    2013-01-01

    Background Among the various treatments of neurologically involved unstable thoracolumbar burst fractures,the combination of anterior and posterior instrumentation provides the most stable reconstruction.However,the use of both approaches on a trauma patient may increase the morbidity.This study is a retrospective matched cohort study to evaluate the advantages of a single stage posterior approach for spinal canal decompression in combination with circumferential reconstruction by comparing the clinical and radiographic results.Methods From March 2005 to September 2009,patients with matched type spinal fracture,ages at surgery,and involved levels in our institute underwent either a single stage posterior approach (group one,n=12) or traditional combined approach (group two,n=14) for spinal canal decompression and circumferential reconstruction were reviewed.Pre-and post-operative X-ray films were reviewed and changes in Cobb angle of thoracolumbar spine were documented.Intra-operative,post-operative,and general complications were registered.Results The mean follow-up was (27.7±9.6) months (range,14 to 56 months) in group one and (29.2±7.4) months (range,20 to 60 months) in group two (P >0.05).The mean operation time was 214 minutes (range,186-327 minutes) in group one and 284 minutes (range,219-423 minutes) in group two (P <0.05).The average volume of intraoperative blood loss was 1856 ml (range,1250-3480 ml) in group one and 2453 ml (range,1600-3680 ml) in group two (P <0.05).There was no statistical difference between the groups one and two in average vertebral body height loss at the injured level and the average Cobb angle in sagittal plane before and immediately after surgery.Postoperatively,there was an epidural hematoma in one patient in group one and two patients in group two.Bony union after stabilization was obtained in all patients,without loosening or breakage of screws.Loss of correction (5°) was seen in 1 patient in group one at the 6th month

  11. Analytical and experimental investigations into the controlled energy absorption characteristics of thick-walled tubes with circumferential grooves

    Energy Technology Data Exchange (ETDEWEB)

    Darvizeh, Abolfazl [Islamic Azad University, Bandar-e Anzali (Iran, Islamic Republic of); Darvizeh, Mansour; Ansari, Reza; Meshkinzar, Ata [University of Guilan, Rasht (Iran, Islamic Republic of)

    2014-10-15

    In this paper, the energy absorption characteristics of grooved circular tubes are investigated under quasi-static loading condition. For experiments, thick-walled tubes with circumferential grooves are prepared. The grooves divide the thick-walled tube into several shorter thin-walled portions. Specimens are subjected to axial crushing load to observe the effect of distribution of circular grooves on the deformation mechanism and energy absorption capacity. Geometrical parameters of the specimens are designed utilizing the Taguchi method to cover a reasonably wide range of groove length-to-wall thickness ratios. An analytical approach based on the concept of energy dissipation through the plastic hinges is applied. Taking the effect of strain hardening into account, the obtained analytical results are in good agreement with the experimental ones. The agreement between analytical and experimental results may indicate the validity of the proposed analytical approach. Desirable mechanism of deformation observed justifies the pre-forming method for obtaining favorable energy absorption characteristics.

  12. Transverse shear effects on the stress-intensity factor for a circumferentially cracked, specially orthotropic cylindrical shell

    Science.gov (United States)

    Delale, F.; Erdogan, F.

    1977-01-01

    The problem of a cylindrical shell containing a circumferential through crack is considered by taking into account the effect of transverse shear deformations. The formulation is given for a specially orthotropic material within the confines of a linearized shallow shell theory. The particular theory used permits the consideration of all five boundary conditions regarding moment and stress resultants on the crack surface. Consequently, aside from multiplicative constants representing the stress intensity factors, the membrane and bending components of the asymptotic stress fields near the crack tip are found to be identical. The stress intensity factors are calculated separately for a cylinder under a uniform membrane load, and that under a uniform bending moment. Sample results showing the nature of the out-of-plane crack surface displacement and the effect of the Poisson's ratio are presented.

  13. Experimental investigation on fracture toughness of Al6061–graphite by using Circumferential Notched Tensile Specimens

    Directory of Open Access Journals (Sweden)

    Saleemsab Doddamani

    2017-01-01

    Full Text Available This paper presents the experimental work carried out on the fracture behavior of aluminium 6061 (Al6061 and graphite particulate composites. The required specimens are prepared using stir casting method with graphite proportions ranging from 3 to 12 % by weight. The fracture behavior of Al6061-graphite particulate composites produced using stir casting method, was investigated by conducting experiments on Universal Testing Machine (UTM. Circumferential Notched Tensile (CNT specimens were utilized to evaluate the fracture toughness of the composites. From the experiment the fracture toughness KIC= 15.85MPa m1/2 is obtained for Al6061-9% Graphite. Further, the experimental results revealed that, except 12% graphite, the fracture toughness of Al6061-graphite was observed to increases with an increase in weight percentage of graphite. The experimental results reinforce that Al6061-graphite particulate MMCs are suitable for automotive and aerospace applications requiring high fracture toughness apart from good wear resistance.

  14. Task IV: Development of Circumferential Inlet Distortion through a Representative Eleven Stage High-speed Axial Compressor

    Science.gov (United States)

    Tan, Choon-Sooi; Suder, Kenneth (Technical Monitor)

    2003-01-01

    The concepts and the procedure developed in Task I and Task III were used to determine the response of an eleven-stage high-speed compressor to an inlet distortion of 180 deg. circumferential extent for contrasting against its performance under uniform inlet flow. Using the computed results at the inlet to and outlet of the compressor, the computed total pressure ratio and efficiency for the clean condition are determined to be 14.22 and 76.9 percent respectively. As for the distorted case, these are determined to be 10.35 and 71.8 percent respectively, showing deterioration 76.9 percent vs 71.8 percent). The physical consistency of the computed flow field was assessed as a means of demonstrating the applicability and utility of the body force representation for inlet distortion computations. Specifically the computed evolution of the distorted pattern in static pressure and total pressure from compressor inlet to exit is examined. For the eleven-stage compressor examined here, the deterioration in performance has been found to be particularly severe in the last 2 stages. This suggests that the last two stages could be redesigned to alleviate the observed deterioration thus making the compressor performance insensitive to circumferential inlet distortion. This can potentially be accomplished by first determining what should the body force distribution of the last two stages should be to achieve minimal or no deterioration in performance in the last two stages. One can then in principle proceed to determine the blade design to yield such a body force distribution.

  15. CFD Study of the Hydrocarbon Boost Low-Pressure Inducer and Kicker in the Presence of a Circumferential Groove

    Science.gov (United States)

    Coker, Robert

    2011-01-01

    Results are presented of a computational fluid dynamics (CFD) study done in support of Marshall Space Flight Center's (MSFC) sub-scale water flow experiments of the Hydrocarbon Boost (HCB) Oxidizer Turbopump (OTP) being developed by the Air Force Research Laboratory (AFRL) and Aerojet. A circumferential groove may be added to the pump to reduce synchronous cavitation and subsequent bearing loads at a minimal performance cost. However, the energy may reappear as high order cavitation (HOC) that spans a relatively large frequency range. Thus, HOC may have implications for the full-scale OTP inducer in terms of reduced structural margin at higher mode frequencies. Simulations using the LOCI/Stream CFD program were conducted in order to explore the fluid dynamical impact of the groove on the low-pressure inducer and kicker. It was found that the circumferential groove has minimal head performance impact, but causes back-flowing high-swirl fluid to interact with the nearly-axial incoming fluid just above the inducer blades. The high-shear interface between the fluids is Kelvin-Helmholtz unstable, resulting in trains of low pressure regions or 'pearls' forming near the upstream edge of the groove. When the static pressure in these regions becomes low enough and they get cut by the blade leading edge, HOC is thought to occur. Although further work is required, the numerical models indicate that HOC will occur in the runbox of the AFRL/Aerojet HCB OTP. Comparisons to the ongoing water flow experiments will be discussed, as well as possible designs that may mitigate HOC while continuing to reduce synchronous cavitation. December 2011 MSS/LPS/SPS Joint Subcommittee Meeting ABSTRACT SUBMITTAL FORM

  16. OUTCOME OF POSTEROLATERAL FUSION VERSUS CIRCUMFERENTIAL FUSION WITH CAGE FOR LUMBAR STENOSIS AND LOW DEGREE LUMBAR SPONDYLOLISTHESIS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Objective To evaluate the outcome of two methods for stabilization and fusion: posterolateral fusion and circumferential fusion involving posterior lumbar interbody fusion for lumbar stenosis with Grades 1 and 2 lumbar spondylolisthesis. Methods From April 1998 to April 2003, 45 patients suffering from lumbar stenosis with low degree lumbar spondylolisthesis treated in our hospital were retrospectively reviewed and assigned to two groups. Among them, 24 patients (group A) were treated with instrumented posterolateral fusion and 21 patients (group B) with instrumented circumferential fusion. The two groups were compared for clinical and radiological outcomes. Results All patients were followed up for 12 to 72 months. In group A, results showed preoperative clinical symptoms disappeared completely in 12 of 24 patients, and pain relief was seen in 91.7% (22/24). Two cases suffered from residual symptoms. Twenty-two cases obtained complete reduction of olisthy vertebral bodies, and anatomical reduction rate was 91.7%. No infection or neurological complication occurred in this group. In group B, results showed preoperative clinical symptoms disappeared completely in 13 of 21 patients, and pain relief was seen in 90. 5% ( 19/21 ). One case suffered from residual symptoms. Twenty cases obtained complete reduction of the olisthy vertebral bodies, and anatomical reduction rate was 95.2%. Four cases of infection or neurological complication occurred in this group. Both groups indicated no significant difference in clinical outcomes and anatomical reduction rate during followup. But group A had better intraoperative circumstances and postoperative outcome than group B, while group B had better postoperative parameters in X-ray of Angle of Slipping and Disc Index than group A.Conclusions The first choice of surgical method for lumbar stenosis with low degree lumbar spondylolisthesis is instrumented posterolateral fusion. Only when patients suffer from severe preoperative disc

  17. Fracture problem for an external circumferential crack in a functionally graded superconducting cylinder subjected to a parallel magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Z. [Department of Engineering Mechanics, Shijiazhuang Tiedao University, Shijiazhuang 050043 (China); Gao, S.W. [College of Civil Engineering, Hebei Institute of Architecture and Civil Engineering, Zhangjiakou 075000 (China); Feng, W.J., E-mail: wjfeng9999@126.com [Department of Engineering Mechanics, Shijiazhuang Tiedao University, Shijiazhuang 050043 (China)

    2016-02-15

    Highlights: • External circumferential crack problem of superconducting cylinder is investigated. • A functionally graded superconducting cylinder is analyzed. • The magnetically impermeable crack surface condition is applied. • The generalized Irie-Yamafuji critical state model outside the crack region is adopted. - Abstract: In this study, the multiple isoparametric finite element method (MIFEM) is used to investigate external circumferential crack problem of a functionally graded superconducting cylinder subjected to electromagnetic forces. The superconducting cylinder is composed by Bi2223/Ag composite with material parameters varying. A crack reference region is defined to reflect the effects of crack on flux and current densities, and the magnetically impermeable crack surface condition and the generalized Irie–Yamafuji critical state model outside the crack region are adopted. The distributions of magnetic flux density in the superconducting cylinder are obtained analytically for both the zero-field cooling (ZFC) and the field cooling (FC) activation processes. Based on the MIFEM, the stress intensity factors (SIFs) at crack fronts in the process of field ascent and/or descent are then numerically calculated. It is interesting to note from numerical results that for the present crack model in the ZFC activation process, the crack is easily propagate and grow with the applied field increases, and that in the field descent process of either the ZFC case or FC case, the crack generally does not propagate. In addition, in the field ascent process of the ZFC case, the SIFs depend on not only the crack depths and model parameters but also the applied field. The present study should be helpful to the design and application of high-temperature superconductors with external edge cracks.

  18. Total hip replacement using hemi-circumferential interposition acetabuloplasty for acetabular deficiency in post-Perthes deformities: technique and long-term results

    NARCIS (Netherlands)

    D. Haverkamp; H. Eijer; R.K. Marti

    2006-01-01

    We describe a technique of hemi-circumferential interposition grafting that allows placement of the cup in the anatomical position of the original acetabulum in the rare cases of post-Perthes or Perthes-like deformities of the femoral head combined with a steep and shallow acetabulum. This technique

  19. Polysaccharide Degradation

    Science.gov (United States)

    Stone, Bruce A.; Svensson, Birte; Collins, Michelle E.; Rastall, Robert A.

    An overview of current and potential enzymes used to degrade polysaccharides is presented. Such depolymerases are comprised of glycoside hydrolases, glycosyl transferases, phosphorylases and lyases, and their classification, active sites and action patterns are discussed. Additionally, the mechanisms that these enzymes use to cleave glycosidic linkages is reviewed as are inhibitors of depolymerase activity; reagents which react with amino acid residues, glycoside derivatives, transition state inhibitors and proteinaceous inhibitors. The characterization of various enzymes of microbial, animal or plant origin has led to their widespread use in the production of important oligosaccharides which can be incorporated into food stuffs. Sources of polysaccharides of particular interest in this chapter are those from plants and include inulin, dextran, xylan and pectin, as their hydrolysis products are purported to be functional foods in the context of gastrointestinal health. An alternative use of degraded polysaccharides is in the treatment of disease. The possibility exists to treat bacterial exopolysaccharide with lyases from bacteriophage to produce oligosaccharides exhibiting bioactive sequences. Although this area is currently in its infancy the knowledge is available to investigate further.

  20. Failure analysis of retired steam generator tubings

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hong Pyo; Kim, J. S.; Hwang, S. S. and others

    2005-04-15

    Degradation of steam generator leads to forced outage and extension of outage, which causes increase in repair cost, cost of purchasing replacement power and radiation exposure of workers. Steam generator tube rupture incident occurred in Uljin 4 in 2002, which made public sensitive to nuclear power plant. To keep nuclear energy as a main energy source, integrity of steam generator should be demonstrated. Quantitative relationship between ECT(eddy current test) signal and crack size is needed in assesment of integrity of steam generator in pressurized water reactor. However, it is not fully established for application in industry. Retired steam generator of Kori 1 has many kinds of crack such as circumferential and axial primary water stress corrosion crack and outer diameter stress corrosion crack(ODSCC). So, it can be used in qualifying and improving ECT technology and in condition monitoring assesment for crack detected in ISI(in service inspection). In addition, examination of pulled tube of Kori 1 retired steam generator will give information about effectiveness of non welded sleeving technology which was employed to repair defect tubes and remedial action which was applied to mitigate ODSCC. In this project, hardware such as semi hot lab. for pulled tube examination and modification transportation cask for pulled tube and software such as procedure of transportation of radioactive steam generator tube and non-destructive and destructive examination of pulled tube were established. Non-destructive and destructive examination of pulled tubes from Kori 1 retired steam generator were performed in semi hot lab. Remedial actions applied to Kori 1 retired steam generator, PWSCC trend and bulk water chemistry and crevice chemistry in Kori 1 were evaluated. Electrochemical decontamination technology for pulled tube was developed to reduce radiation exposure and enhance effectiveness of pulled tube examination. Multiparameter algorithm developed at ANL, USA was

  1. Radiofrequency Ablation Mapping with Circumferential Catheter for Paroxys-mal Atrial Fibrillation Originating From the Pulmonary Veins

    Institute of Scientific and Technical Information of China (English)

    刘震; 吴书林; 杨平珍; 方咸宏; 李海杰; 陈泗林; 詹贤章; 薛玉梅

    2002-01-01

    Objectives To assessed thefeasibility and effectiveness of electrophysiologicalmapping of pulmonary veins with a circumferential 10-electrode catheter and radiofrequency catheter abla-tion therapy for patients with paroxysmal atrial fibril-lation. Background Standard mapping and ablationof focal sources of atrial fibrillation are associated withvery long procedure times and low efficacy. Mappingand ablation pulmonary veins guide with a circularcatheter could overcome these limitations. Methods16 patients [male 11, female 5, mean age (51 +14.5) years] with paroxysmal atrial fibrillation refrac-tory to antiarrhythmic drugs were included in thisgroup. A circumferential 10-electrode catheter wasused to pulmonary vein mapping during sinus rhythm orCSd pacing to determine the origin of atrial prematurecontractions. When the ablative target pulmonary veinwas found, the pulmonary vein potentials' distributionand activation were assessment pulmonary veins' ostialablation was performed at the segments showing earliestactivation of pulnonary vein potentials. The end pointwas designed: 1 ) elimination of pulmonary vein po-tential; 2) pulmonary vein potential dissociation fromatrial waves; 3) atrial ectopic beats disappear. ResultsA total of 36 pulmonary veins were ablated, in-cluding 16 left superior, 12 right superior, 7 left in-ferior and 1 right inferior. 1 pulmonary vein in 2 pa-tients was ablated, 2 pulmonary veins in 8 patientswere ablated, 3 pulmonary veins were ablated in 5patients and 4 pulmonary veins were ablated in 1 pa-tient. Procedure duration and fluoroscopy time respec-tively were 186.7 _+ 63.8 min and 51.5 + 15.0 min.During the follow-up 1- 12 months, 11 patients(68.7 % ) were free of AF without any antiarrhythmicdrugs, 2 of them were reablation, effective in 3/16(18.7%) and unsuccessful in 2/16 (12.6%) . 2cases recurred with atrial premature, 1 was treated withamiodarone and the other was repeat electrophysiologi-cal mapping and ablation, 5 cases with

  2. EXPERIMENTAL RESEARCH ON AERODYNAMIC PERFORMANCE AND EXIT FLOW FIELD OF LOW PRESSURE AXIAL FLOW FAN WITH CIRCUMFERENTIAL SKEWED BLADES

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this article, the low pressure axial flow fan with circumferential skewed rotor blade, including the radial blade, the forward-skewed blade and the backward-skewed blade, was studied with experimental methods. The aerodynamic performance of the rotors was measured. At the design condition at outlet of the rotors, detailed flow measurements were performed with a five-hole probe and a Hot-Wire Anemometer (HWA). The results show that compared to the radial rotor, the forward-skewed rotor demonstrates a wider Stable Operating Range (SOR), is able to reduce the total pressure loss in the hub region and make main loading of blade accumulating in the mid-span region. There is a wider wake in the upper mid-span region of the forward-skewed rotor. Compared to the radial rotor, in the backward-skewed rotor there is higher total pressure loss near the hub and shroud regions and lower loss in the mid-span region. In addition, the velocity deficit in the wake is lower at mid-span of the backward-skewed rotor than the forward-skewed rotor.

  3. Wall thickness measurement using resonant phenomena of circumferential Lamb waves generated by plural transducer elements located evenly on girth

    Science.gov (United States)

    Nishino, Hideo; Iwata, Kodai; Ishikawa, Masashi

    2016-07-01

    We present a novel method of measuring the pipe wall thickness using the resonance of the circumferential (C-) Lamb wave generated by a piezoelectric ring-shaped sensor (PS). The PS is a special device for an axially propagating torsional wave; however, the C-Lamb waves are generated simultaneously as spurious signals owing to the structure of the PS. Particularly under resonant conditions, the C-Lamb waves are dominantly generated, distorting the axially propagating wave. In this method, these troublesome spurious signals are used effectively for the measurement of the wall thickness under the PS location that is a dead zone of the PS itself. The method can compensate for its drawback, namely, the dead zone problem, without using additional instruments. In this study, the mechanisms of the generation and resonance of the C-Lamb waves were first explained. Secondly, the principle of the wall thickness estimation utilizing the resonance of the C-Lamb waves was proposed. Finally, experimental verifications were carried out. The estimated wall thicknesses agreed very well (maximum 1.5% error) with those measured by a micrometer caliper under suitable resonant conditions.

  4. Effect of anxiety and depression on the recurrence of persistent atrial fibrillation after circumferential pulmonary vein ablation

    Institute of Scientific and Technical Information of China (English)

    YU Sheng-bo; HU Wei; ZHAO Qing-yan; QIN Mu; HUANG He; CUI Hong-ying; HUANG Cong-xin

    2012-01-01

    Background The effects of anxiety and depression on the recurrence of persistent atrial fibrillation (AF) after circumferential pulmonary vein ablation (CPVA) are not clear.Whether CPVA can alleviate the anxiety and depression symptoms of persistent AF patients is unknown.Methods One hundred and sixty-four patients with persistent AF,of which 43 treated with CPVA (CPVA group) and 103 treated with anti-arrhythmics drugs (medicine group),were enrolled.The Zung Self-Rating Anxiety Scale (SAS),and Zung Self-Rating Depression Scale (SDS) were assessed before and 12 months after treatment in all patients.Results The scores of SAS (40.33±7.90 vs.49.76±9.52,P <0.01) and SDS (42.33±8.73 vs.48.17±8.77,P <0.01)decreased 12 months after CPVA.Over 12 months follow-up,AF relapsed in 17 patients in CPVA group.Compared with the data in the recurrent group (17 patients),the scores of SAS and SDS were significantly lower in the non-recurrent group (26 patients) at baseline.The results of multivariate Logistic regression analysis showed normal scores of SAS and SDS were the independent risk factors of AF recurrence after CPVA.Conclusions Anxiety and depression increase the recurrence risk of persistent AF after CPVA.CPVA can ameliorate the anxiety and depression symptoms in patients with persistent AF.

  5. New matrix method for response analysis of circumferentially stiffened non-circular cylindrical shells under harmonic pressure

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Based on the governing equation of vibration of a kind of cylindrical shells written in a matrix differential equation of the first order, a new matrix method is presented for steady-state vibration analysis of a noncircular cylindrical shell simply supported at two ends and circumferentially stiffened by rings under harmonic pressure. Its difference from the existing works by Yamada and Irie is that the matrix differential equation is solved by using the extended homogeneous capacity precision integration approach other than the Runge-Kutta-Gill integration method. The transfer matrix can easily be determined by a high precision integration scheme. In addition, besides the normal interacting forces, which were commonly adopted by researchers earlier, the tangential interacting forces between the cylindrical shell and the rings are considered at the same time by means of the Dirac-δ function. The effects of the exciting frequencies on displacements and stresses responses have been investigated. Numerical results show that the proposed method is more efficient than the aforementioned method.

  6. Nondestructive Evaluation of Functionally Graded Subsurface Damage on Cylinders in Nuclear Installations Based on Circumferential SH Waves

    Directory of Open Access Journals (Sweden)

    Zhen Qu

    2016-01-01

    Full Text Available Subsurface damage could affect the service life of structures. In nuclear engineering, nondestructive evaluation and detection of the evaluation of the subsurface damage region are of great importance to ensure the safety of nuclear installations. In this paper, we propose the use of circumferential horizontal shear (SH waves to detect mechanical properties of subsurface regions of damage on cylindrical structures. The regions of surface damage are considered to be functionally graded material (FGM and the cylinder is considered to be a layered structure. The Bessel functions and the power series technique are employed to solve the governing equations. By analyzing the SH waves in the 12Cr-ODS ferritic steel cylinder, which is frequently applied in the nuclear installations, we discuss the relationship between the phase velocities of SH waves in the cylinder with subsurface layers of damage and the mechanical properties of the subsurface damaged regions. The results show that the subsurface damage could lead to decrease of the SH waves’ phase velocity. The gradient parameters, which represent the degree of subsurface damage, can be evaluated by the variation of the SH waves’ phase velocity. Research results of this study can provide theoretical guidance in nondestructive evaluation for use in the analysis of the reliability and durability of nuclear installations.

  7. Hyaluronate degradation affects ventricular function of the early postlooped embryonic rat heart in situ.

    Science.gov (United States)

    Baldwin, H S; Lloyd, T R; Solursh, M

    1994-02-01

    Hyaluronic acid is the major glycosaminoglycan of the early cardiac extracellular matrix or "cardiac jelly," yet little is known about its role in the ontogeny of early ventricular performance. To investigate the in situ effect of hyaluronate degradation on ventricular function, whole rat embryos were cultured in rat serum alone (control embryos) or rat serum plus 20 TRU/mL of Streptomyces hyaluronidase (treatment embryos) from gestational day 9.5 (before formation of the heart tube) through initial looping of the heart. Cardiac function was measured before looping (24 hours in culture) and immediately after looping (36 hours in culture) by video motion analysis of the external wall motion of the bulbus cordis and primitive ventricle. Degradation of hyaluronic acid in the treated embryos was confirmed by Alcian blue staining at pH 2.5. Significant increases in heart rate, circumferential shortening fraction, maximum velocity of circumferential contraction, and maximum velocity of circumferential relaxation were observed with looping in both control and treatment embryos. Although there was minimal difference in ventricular performance between control and treatment embryos before looping, there was a significant increase in all parameters of ventricular performance in the hyaluronidase-treated embryos immediately after looping of the heart. Endocardial cushions were absent in hyaluronidase-treated embryos, and an additional group of embryos cultured in the presence of Streptomyces hyaluronidase for 48 to 72 hours failed to develop endocardial cushions. These experiments are the first to (1) document a quantifiable increase in ventricular performance during early cardiac looping and (2) demonstrate that hyaluronate degradation results in abnormal endocardial cushion formation and altered ventricular performance of the postlooped heart.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. Accuracy of High-Resolution MRI with Lumen Distention in Rectal Cancer Staging and Circumferential Margin Involvement Prediction

    Energy Technology Data Exchange (ETDEWEB)

    Iannicelli, Elsa; Di Renzo, Sara [Radiology Institute, Faculty of Medicine and Psychology, University of Rome, Sapienza, Sant' Andrea Hospital, Rome 00189 (Italy); Department of Surgical and Medical Sciences and Translational Medicine, Faculty of Medicine and Psychology, University of Rome, Sapienza, Sant' Andrea Hospital, Rome 00189 (Italy); Ferri, Mario [Department of Surgical and Medical Sciences and Translational Medicine, Faculty of Medicine and Psychology, University of Rome, Sapienza, Sant' Andrea Hospital, Rome 00189 (Italy); Pilozzi, Emanuela [Department of Clinical and Molecular Sciences, Faculty of Medicine and Psychology, University of Rome, Sapienza, Sant' Andrea Hospital, Rome 00189 (Italy); Di Girolamo, Marco; Sapori, Alessandra [Radiology Institute, Faculty of Medicine and Psychology, University of Rome, Sapienza, Sant' Andrea Hospital, Rome 00189 (Italy); Department of Surgical and Medical Sciences and Translational Medicine, Faculty of Medicine and Psychology, University of Rome, Sapienza, Sant' Andrea Hospital, Rome 00189 (Italy); Ziparo, Vincenzo [Department of Surgical and Medical Sciences and Translational Medicine, Faculty of Medicine and Psychology, University of Rome, Sapienza, Sant' Andrea Hospital, Rome 00189 (Italy); David, Vincenzo [Radiology Institute, Faculty of Medicine and Psychology, University of Rome, Sapienza, Sant' Andrea Hospital, Rome 00189 (Italy); Department of Surgical and Medical Sciences and Translational Medicine, Faculty of Medicine and Psychology, University of Rome, Sapienza, Sant' Andrea Hospital, Rome 00189 (Italy)

    2014-07-01

    To evaluate the accuracy of magnetic resonance imaging (MRI) with lumen distention for rectal cancer staging and circumferential resection margin (CRM) involvement prediction. Seventy-three patients with primary rectal cancer underwent high-resolution MRI with a phased-array coil performed using 60-80 mL room air rectal distention, 1-3 weeks before surgery. MRI results were compared to postoperative histopathological findings. The overall MRI T staging accuracy was calculated. CRM involvement prediction and the N staging, the accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were assessed for each T stage. The agreement between MRI and histological results was assessed using weighted-kappa statistics. The overall MRI accuracy for T staging was 93.6% (k = 0.85). The accuracy, sensitivity, specificity, PPV and NPV for each T stage were as follows: 91.8%, 86.2%, 95.5%, 92.6% and 91.3% for the group ≤ T2; 90.4%, 94.6%, 86.1%, 87.5% and 94% for T3; 98,6%, 85.7%, 100%, 100% and 98.5% for T4, respectively. The predictive CRM accuracy was 94.5% (k = 0.86); the sensitivity, specificity, PPV and NPV were 89.5%, 96.3%, 89.5%, and 96.3% respectively. The N staging accuracy was 68.49% (k = 0.4). MRI performed with rectal lumen distention has proved to be an effective technique both for rectal cancer staging and involved CRM predicting.

  9. Sparing Sphincters and Laparoscopic Resection Improve Survival by Optimizing the Circumferential Resection Margin in Rectal Cancer Patients.

    Science.gov (United States)

    Keskin, Metin; Bayraktar, Adem; Sivirikoz, Emre; Yegen, Gülcin; Karip, Bora; Saglam, Esra; Bulut, Mehmet Türker; Balik, Emre

    2016-02-01

    The goal of rectal cancer treatment is to minimize the local recurrence rate and extend the disease-free survival period and survival. For this aim, obtainment of negative circumferential radial margin (CRM) plays an important role. This study evaluated predictive factors for positive CRM status and its effect on patient survival in mid- and distal rectal tumors.Patients who underwent curative resection for rectal cancer were included. The main factors were demographic data, tumor location, surgical technique, neoadjuvant therapy, tumor diameter, tumor depth, lymph node metastasis, mesorectal integrity, CRM, the rate of local recurrence, distant metastasis, and overall and disease-free survival. Statistical analyses were performed by using the Chi-squared test, Fisher exact test, Student t test, Mann-Whitney U test and the Mantel-Cox log-rank sum test.A total of 420 patients were included, 232 (55%) of whom were male. We observed no significant differences in patient characteristics or surgical treatment between the patients who had positive CRM and who had negative CRM, but a higher positive CRM rate was observed in patients undergone abdominoperineal resection (APR) (P CRM status. Logistic regression analysis revealed that APR (P CRM status. Moreover, positive CRM was associated with decreased 5-year overall and disease-free survival (P = 0.002 and P = 0.004, respectively).This large single-institution series demonstrated that APR and open resection were independent predictive factors for positive CRM status in rectal cancer. Positive CRM independently decreased the 5-year overall and disease-free survival rates.

  10. The May 2005 eruption of Fernandina volcano, Galápagos: The first circumferential dike intrusion observed by GPS and InSAR

    KAUST Repository

    Chadwick, William W Jr

    2010-12-15

    The May 2005 eruption of Fernandina volcano, Galápagos, occurred along circumferential fissures parallel to the caldera rim and fed lava flows down the steep southwestern slope of the volcano for several weeks. This was the first circumferential dike intrusion ever observed by both InSAR and GPS measurements and thus provides an opportunity to determine the subsurface geometry of these enigmatic structures that are common on Galápagos volcanoes but are rare elsewhere. Pre- and post- eruption ground deformation between 2002 and 2006 can be modeled by the inflation of two separate magma reservoirs beneath the caldera: a shallow sill at ~1 km depth and a deeper point-source at ~5 km depth, and we infer that this system also existed at the time of the 2005 eruption. The co-eruption deformation is dominated by uplift near the 2005 eruptive fissures, superimposed on a broad subsidence centered on the caldera. Modeling of the co-eruption deformation was performed by including various combinations of planar dislocations to simulate the 2005 circumferential dike intrusion. We found that a single planar dike could not match both the InSAR and GPS data. Our best-fit model includes three planar dikes connected along hinge lines to simulate a curved concave shell that is steeply dipping (~45-60°) toward the caldera at the surface and more gently dipping (~12-14°) at depth where it connects to the horizontal sub-caldera sill. The shallow sill is underlain by the deep point source. The geometry of this modeled magmatic system is consistent with the petrology of Fernandina lavas, which suggest that circumferential eruptions tap the shallowest parts of the system, whereas radial eruptions are fed from deeper levels. The recent history of eruptions at Fernandina is also consistent with the idea that circumferential and radial intrusions are sometimes in a stress-feedback relationship and alternate in time with one another. © 2010 Springer-Verlag.

  11. Magnetic resonance-derived circumferential strain provides a superior and incremental assessment of improvement in contractile function in patients early after ST-segment elevation myocardial infarction

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Dennis T.L.; Psaltis, Peter J. [University of Adelaide, Discipline of Medicine, Adelaide (Australia); South Australian Health and Medical Research Institute (SAHMRI), Adelaide (Australia); Monash Cardiovascular Research Centre, Department of Medicine (Monash Medical Centre)Monash University and Monash Heart, Clayton, VIC (Australia); Leong, Darryl P.; Weightman, Michael J.; Richardson, James D.; Worthley, Matthew I.; Worthley, Stephen G. [University of Adelaide, Discipline of Medicine, Adelaide (Australia); Dundon, Benjamin K.; Leung, Michael C.H.; Meredith, Ian T. [Monash Cardiovascular Research Centre, Department of Medicine (Monash Medical Centre)Monash University and Monash Heart, Clayton, VIC (Australia)

    2014-06-15

    We evaluate whether circumferential strain derived from grid-tagged CMR is a better method for assessing improvement in segmental contractile function after STEMI compared to late gadolinium enhancement (LGE). STEMI patients post primary PCI underwent baseline CMR (day 3) and follow-up (day 90). Cine, grid-tagged and LGE images were acquired. Baseline LGE infarct hyperenhancement was categorised as ≤25 %, 26-50 %, 51-75 % and >75 % hyperenhancement. The segmental baseline circumferential strain (CS) and circumferential strain rate (CSR) were calculated from grid-tagged images. Segments demonstrating an improvement in wall motion of ≥1 grade compared to baseline were regarded as having improved segmental contractile-function. Forty-five patients (aged 58 ± 12 years) and 179 infarct segments were analysed. A baseline CS cutoff of -5 % had sensitivity of 89 % and specificity of 70 % for detection of improvement in segmental-contractile-function. On receiver-operating characteristic analysis for predicting improvement in contractile function, AUC for baseline CS (0.82) compared favourably to LGE hyperenhancement (0.68), MVO (0.67) and baseline-CSR (0.74). On comparison of AUCs, baseline CS was superior to LGE hyperenhancement and MVO in predicting improvement in contractile function (P < 0.001). On multivariate-analysis, baseline CS was the independent predictor of improvement in segmental contractile function (P < 0.001). Grid-tagged CMR-derived baseline CS is a superior predictor of improvement in segmental contractile function, providing incremental value when added to LGE hyperenhancement and MVO following STEMI. (orig.)

  12. Assessment of circumferential endocardial extent of myocardial edema and infarction in patients with reperfused acute myocardial infarction: a cardiovascular magnetic resonance study.

    Science.gov (United States)

    Ota, Shingo; Tanimoto, Takashi; Hirata, Kumiko; Orii, Makoto; Shiono, Yasutsugu; Shimamura, Kunihiro; Ishibashi, Kohei; Yamano, Takashi; Ino, Yasushi; Kitabata, Hironori; Yamaguchi, Tomoyuki; Kubo, Takashi; Imanishi, Toshio; Akasaka, Takashi

    2014-01-01

    T2 weighted (T2W) images on cardiovascular magnetic resonance (CMR) visualizes myocardial edema, which reflects the myocardial area at risk (AAR) in reperfused acute myocardial infarction (AMI). Late gadolinium enhancement (LGE) demonstrates myocardial infarction. LGE images cover the whole left ventricle, but T2W images are obtained from a few slices of the left ventricle due to the long sequence time, so the quantification of AAR of the entire left ventricle is difficult. We hypothesize that we can quantify AAR with only LGE images if there is a strong correlation between the circumferential endocardial extent of myocardial edema and infarction. Thirty patients with first AMI were enrolled. All patients underwent successfully reperfusion therapy and CMR was performed within the first week after the event. We measured the circumferential extent of edema and infarction on short-axis views (T2 angle and LGE angle), respectively. A total of 82 short-axis slices showed transmural edema on T2W images. Corresponding LGE images were analyzed for the circumferential extent of infarction. The median [interquartile range] of T2 angle and DE angle were 147° [116°-219°] and 134° [104°-200°] in patients with LAD culprit lesion, 91° [87°-101°] and 85° [80°-90°] in LCX, and 110° [94°-123°] and 104° [89°-118°] in RCA, respectively. T2 angle was well correlated with LGE angle (r = 0.99, P infarction in reperfused AMI. Thus, T2 weighted imaging can be skipped to quantify the amount of AAR.

  13. Circumferential decompression via the posterior approach for the surgical treatment of multilevel thoracic ossification of the posterior longitudinal ligaments: a single institution comparative study

    Institute of Scientific and Technical Information of China (English)

    Liu Xiao; Zhu Bin; Liu Xiaoguang; Liu Zhongjun; Dang Gengting

    2014-01-01

    Background The treatment strategies for multilevel thoracic ossification of the posterior longitudinal ligaments (T-OPLL) were rarely reported.The aim of this study was to investigate the clinical outcomes and complications of circumferential decompression for multilevel T-OPLL and compare two different methods in the management of the OPLL (resection or floating).Methods Data of sequentially treated patients who received surgical treatment for thoracic spinal stenosis caused by multilevel T-OPLL from January 2005 to February 2012 were retrospectively reviewed.Based on the surgical approaches applied,the patients were divided into two groups.Group A consisted the patients who received posterior decompression and group B consisted the patients who received circumferential decompression via the posterior approach.Group B was further divided into two subgroups:subgroup 1 (the resection group) where the OPLL was completely resected and subgroup 2 (the floating group) where the OPLL was floated.Results A total of 49 patients were included in the study.Fourteen patients with single posterior decompression were included in group A and 35 patients who received circumferential decompression were included in group B.In group B,29 patients had complete resection of the ossified posterior longitudinal ligaments,while the other six underwent a flotation procedure.The follow-up data were available in 39 patients.Mean JOA scores improved from 5.4 ± 1.8 to 7.5 ± 2.8 in group A and from 3.7 ± 1.8 to 7.9 ± 2.4 in group B.The main complications included cerebrospinal fluid (CSF) leakage and postoperative neurologic deterioration (ND).Twenty-three of the 25 cases with postoperative CSF leakage achieved a complete recovery at the last follow-up and 12 of the 15 cases with ND achieved some neurological improvement at the last follow-up.Conclusions Circumferential decompression via the posterior approach is an effective surgical method for thoracic spinal stenosis caused by

  14. PEM fuel cell degradation

    Energy Technology Data Exchange (ETDEWEB)

    Borup, Rodney L [Los Alamos National Laboratory; Mukundan, Rangachary [Los Alamos National Laboratory

    2010-01-01

    The durability of PEM fuel cells is a major barrier to the commercialization of these systems for stationary and transportation power applications. While significant progress has been made in understanding degradation mechanisms and improving materials, further improvements in durability are required to meet commercialization targets. Catalyst and electrode durability remains a primary degradation mode, with much work reported on understanding how the catalyst and electrode structure degrades. Accelerated Stress Tests (ASTs) are used to rapidly evaluate component degradation, however the results are sometimes easy, and other times difficult to correlate. Tests that were developed to accelerate degradation of single components are shown to also affect other component's degradation modes. Non-ideal examples of this include ASTs examining catalyst degradation performances losses due to catalyst degradation do not always well correlate with catalyst surface area and also lead to losses in mass transport.

  15. Muscle transposition and circumferential vacuum-assisted closure to salvage the knee joint in transtibial amputation of the leg: case report.

    Science.gov (United States)

    Tuncer, Serdar; Karaca, Sinan

    2011-06-01

    Degloving injury is the avulsion of the skin off the underlying muscle and bone, which may also involve the latter structures in high-energy trauma. This study reports the case of a 33-year-old male patient who sustained a motorcycle accident and presented with hypovolemic shock, multiple fractures, and multiplanar degloving injury of the leg. The foot and distal leg was not salvageable, and a transtibial amputation with anterior transposition of the posterior compartment muscles was performed; however, a circumferential skin necrosis involving the stump and the knee joint occurred. The wound granulated rapidly using circumferential vacuum-assisted closure therapy and subsequently repaired with split thickness skin grafts. The authors found the topical negative pressure using the Vacuum Assisted Closure (VAC) technique Trademark KCI, Texas, USA, method to be helpful in the care of lower extremity degloving injury, enabling less frequent dressing changes and facilitating formation of granulation tissue with rapid preparation of the wound bed for salvage of the knee joint.

  16. Circumferential lesion formation around the pulmonary veins in the left atrium with focused ultrasound using a 2D-array endoesophageal device: a numerical study

    Energy Technology Data Exchange (ETDEWEB)

    Pichardo, Samuel; Hynynen, Kullervo [Imaging Research-Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Room C713, Toronto, ON M4N 3M5 (Canada)

    2007-08-21

    Atrial fibrillation (AF) is the most frequently sustained cardiac arrhythmia affecting humans. The electrical isolation by ablation of the pulmonary veins (PVs) in the left atrium (LA) of the heart has been proven as an effective cure of AF. The ablation consists mainly in the formation of a localized circumferential thermal coagulation of the cardiac tissue surrounding the PVs. In the present numerical study, the feasibility of producing the required circumferential lesion with an endoesophageal ultrasound probe is investigated. The probe operates at 1 MHz and consists of a 2D array with enough elements (114 x 20) to steer the acoustic field electronically in a volume comparable to the LA. Realistic anatomical conditions of the thorax were considered from the segmentation of histological images of the thorax. The cardiac muscle and the blood-filled cavities in the heart were identified and considered in the sound propagation and thermal models. The influence of different conditions of the thermal sinking in the LA chamber was also studied. The circumferential ablation of the PVs was achieved by the sum of individual lesions induced with the proposed device. Different scenarios of lesion formation were considered where ultrasound exposures (1, 2, 5 and 10 s) were combined with maximal peak temperatures (60, 70 and 80 {sup 0}C). The results of this numerical study allowed identifying the limits and best conditions for controlled lesion formation in the LA using the proposed device. A controlled situation for the lesion formation surrounding the PVs was obtained when the targets were located within a distance from the device in the range of 26 {+-} 7 mm. When combined with a maximal temperature of 70 {sup 0}C and an exposure time between 5 and 10 s, this distance ensured preservation of the esophageal structures, controlled lesion formation and delivery of an acoustic intensity at the transducer surface that is compatible with existing materials. With a peak

  17. Thraustochytrid protists degrade hydrocarbons

    Digital Repository Service at National Institute of Oceanography (India)

    Raikar, M.T.; Raghukumar, S.; Vani, V.; David, J.J.; Chandramohan, D.

    Rev, 54 (1990) 305-315. 12 Fedorak P M & Westlake D W S, Microbial degradation of aromatics and saturates in Prudhoe Bay crude oil as determined by glass capillary gas chromatography, Can J Microbiol, (1981) 432-443. 13 Atlas R M, Microbial... degradation of petroleum hydrocarbons: An environmental perspective, Microbiol Rev, 45 (1981) 180-209. 14 Atlas R M, Microbial hydrocarbon degradation- Bioremediation of oil spills, J Chem Tech Biotechnol, 52 (1991) 149-156 15 Venkateswaran K, Iwabuchi T...

  18. Is crack branching under shear loading caused by shear fracture? ——A critical review on maximum circumferential stress theory

    Institute of Scientific and Technical Information of China (English)

    孙宗颀

    2001-01-01

    When a crack is subjected to shear force, crack branching usually occurs. Theoretical study shows that the crack branching under shear loading is caused by tensile stress, but not caused by shear fracture. The co-plane shear fracture could be obtained if compressive stress with given direction is applied to the specimen, subsequently, calculated shear fracture toughness, KⅡ C, is larger than KⅠ C. A prerequisite of possible occurrence of mode Ⅱ fracture was proposed. The study of shear fracture shows that the maximum circumferential stress theory considered its criterion as a parametric equation of a curve in KⅠ, KⅡ plane is incorrect; the predicted ratio KⅡ C/KⅠ C=0.866 is incorrect too.

  19. Self-Expandable Stent for Repairing Coarctation of the Left-Circumferential Aortic Arch with Right-sided Descending Aorta and Aberrant Right Subclavian Artery with Kommerell's Aneurysm.

    Science.gov (United States)

    Khajali, Zahra; Sanati, Hamid Reza; Pouraliakbar, Hamidreza; Mohebbi, Bahram; Aeinfar, Kamran; Zolfaghari, Reza

    2017-01-01

    Endovascular treatment offers a great advantage in the management of main arteries stenoses. However, simultaneous presence of a group of anomalies may complicate the situation. Here we present a case of 21-year-old man with aortic coarctation. Radiographic imaging and angiography demonstrated aortic coarctation of the left-circumferential aortic arch, right-sided descending aorta, and Kommerell's diverticulum at the origin of right subclavian artery. These anomalies have rarely been reported to concurrently exist in the same case and the treatment is challenging. Percutaneous treatment for repair of aortic coarctation was successfully performed with deployment of self-expanding nitinol stents. Follow-up demonstrated the correction of blood pressure and improvement of the symptoms. It appears that deployment of self-expandable nitinol stents present a viable option for the management of coarcted aorta in patients having all or some of these anomalies together.

  20. Syntrophy in Methanogenic Degradation

    NARCIS (Netherlands)

    Worm, P.; Müller, N.; Plugge, C.M.; Stams, A.J.M.; Schink, B.

    2010-01-01

    This chapter deals with microbial communities of bacteria and archaea that closely cooperate in methanogenic degradation and perform metabolic functions in this community that neither one of them could carry out alone. The methanogenic degradation of fatty acids, alcohols, most aromatic compounds, a

  1. Rate of NDF degradation

    DEFF Research Database (Denmark)

    Weisbjerg, Martin Riis; Koukolová, V; Lund, Peter

    2007-01-01

    Degradation profiles for NDF were estimated for 83 samples of grass/grass-clover, 27 samples of cereal whole crop and 14 samples of maize whole crop.......Degradation profiles for NDF were estimated for 83 samples of grass/grass-clover, 27 samples of cereal whole crop and 14 samples of maize whole crop....

  2. Batteries: Imaging degradation

    Science.gov (United States)

    Shearing, Paul R.

    2016-11-01

    The degradation and failure of Li-ion batteries is strongly associated with electrode microstructure change upon (de)lithiation. Now, an operando X-ray tomography approach is shown to correlate changes in the microstructure of electrodes to cell performance, and thereby predict degradation pathways.

  3. Silk structure and degradation.

    Science.gov (United States)

    Liu, Bin; Song, Yu-wei; Jin, Li; Wang, Zhi-jian; Pu, De-yong; Lin, Shao-qiang; Zhou, Chan; You, Hua-jian; Ma, Yan; Li, Jin-min; Yang, Li; Sung, K L Paul; Zhang, Yao-guang

    2015-07-01

    To investigate the structure of silk and its degradation properties, we have monitored the structure of silk using scanning electron microscopy and frozen sections. Raw silk and degummed raw silk were immersed in four types of degradation solutions for 156 d to observe their degradation properties. The subcutaneous implants in rats were removed after 7, 14, 56, 84, 129, and 145 d for frozen sectioning and subsequent staining with hematoxylin and eosin (H.E.), DAPI, Beta-actin and Collagen I immunofluorescence staining. The in vitro weight loss ratio of raw silk and degummed raw silk in water, PBS, DMEM and DMEM containing 10% FBS (F-DMEM) were, respectively, 14%/11%, 12.5%/12.9%, 11.1%/14.3%, 8.8%/11.6%. Silk began to degrade after 7 d subcutaneous implantation and after 145 d non-degraded silk was still observed. These findings suggest the immunogenicity of fibroin and sericin had no essential difference. In the process of in vitro degradation of silk, the role of the enzyme is not significant. The in vivo degradation of silk is related to phagocytotic activity and fibroblasts may be involved in this process to secrete collagen. This study also shows the developing process of cocoons and raw silk.

  4. Intermittent degradation and schizotypy

    Directory of Open Access Journals (Sweden)

    Matthew W. Roché

    2015-06-01

    Full Text Available Intermittent degradation refers to transient detrimental disruptions in task performance. This phenomenon has been repeatedly observed in the performance data of patients with schizophrenia. Whether intermittent degradation is a feature of the liability for schizophrenia (i.e., schizotypy is an open question. Further, the specificity of intermittent degradation to schizotypy has yet to be investigated. To address these questions, 92 undergraduate participants completed a battery of self-report questionnaires assessing schizotypy and psychological state variables (e.g., anxiety, depression, and their reaction times were recorded as they did so. Intermittent degradation was defined as the number of times a subject’s reaction time for questionnaire items met or exceeded three standard deviations from his or her mean reaction time after controlling for each item’s information processing load. Intermittent degradation scores were correlated with questionnaire scores. Our results indicate that intermittent degradation is associated with total scores on measures of positive and disorganized schizotypy, but unrelated to total scores on measures of negative schizotypy and psychological state variables. Intermittent degradation is interpreted as potentially derivative of schizotypy and a candidate endophenotypic marker worthy of continued research.

  5. SPECIFIC DEGRADATION OF WATERSHEDS

    Institute of Scientific and Technical Information of China (English)

    Boubacar KANE; Pierre Y.JULIEN

    2007-01-01

    An extensive database of reservoir sedimentation surveys throughout continental United States is compiled and analyzed to determine specific degradation SD relationships as function of mean annual rainfall R, drainage area A, and watershed slope S. The database contains 1463 field measurements and specific degradation relationships are defined as function of A, R and S. Weak trends and significant variability in the data are noticeable. Specific degradation measurements are log normally distributed with respect to R, A, and S and 95% confidence intervals are determined accordingly. The accuracy of the predictions does not significantly increase as more independent variables are added to the regression analyses.

  6. Degradation of fluorotelomer alcohols

    DEFF Research Database (Denmark)

    Ellis, David A; Martin, Jonathan W; De Silva, Amila O

    2004-01-01

    Human and animal tissues collected in urban and remote global locations contain persistent and bioaccumulative perfluorinated carboxylic acids (PFCAs). The source of PFCAs was previously unknown. Here we present smog chamber studies that indicate fluorotelomer alcohols (FTOHs) can degrade...

  7. Purex diluent degradation

    Energy Technology Data Exchange (ETDEWEB)

    Tallent, O.K.; Mailen, J.C.; Pannell, K.D.

    1984-02-01

    The chemical degradation of normal paraffin hydrocarbon (NPH) diluents both in the pure state and mixed with 30% tributyl phosphate (TBP) was investigated in a series of experiments. The results show that degradation of NPH in the TBP-NPH-HNO/sub 3/ system is consistent with the active chemical agent being a radical-like nitrogen dioxide (NO/sub 2/) molecule, not HNO/sub 3/ as such. Spectrophotometric, gas chromatographic, mass spectrographic, and titrimetric methods were used to identify the degradation products, which included alkane nitro and nitrate compounds, alcohols, unsaturated alcohols, nitro alcohols, nitro alkenes, ketones, and carboxylic acids. The degradation rate was found to increase with increases in the HNO/sub 3/ concentration and the temperature. The rate was decreased by argon sparging to remove NO/sub 2/ and by the addition of butanol, which probably acts as a NO/sub 2/ scavenger. 13 references, 11 figures.

  8. How do polymers degrade?

    Science.gov (United States)

    Lyu, Suping

    2011-03-01

    Materials derived from agricultural products such as cellulose, starch, polylactide, etc. are more sustainable and environmentally benign than those derived from petroleum. However, applications of these polymers are limited by their processing properties, chemical and thermal stabilities. For example, polyethylene terephthalate fabrics last for many years under normal use conditions, but polylactide fabrics cannot due to chemical degradation. There are two primary mechanisms through which these polymers degrade: via hydrolysis and via oxidation. Both of these two mechanisms are related to combined factors such as monomer chemistry, chain configuration, chain mobility, crystallinity, and permeation to water and oxygen, and product geometry. In this talk, we will discuss how these materials degrade and how the degradation depends on these factors under application conditions. Both experimental studies and mathematical modeling will be presented.

  9. Bacteria and lignin degradation

    Institute of Scientific and Technical Information of China (English)

    Jing LI; Hongli YUAN; Jinshui YANG

    2009-01-01

    Lignin is both the most abundant aromatic (phenolic) polymer and the second most abundant raw material.It is degraded and modified by bacteria in the natural world,and bacteria seem to play a leading role in decomposing lignin in aquatic ecosystems.Lignin-degrading bacteria approach the polymer by mechanisms such as tunneling,erosion,and cavitation.With the advantages of immense environmental adaptability and biochemical versatility,bacteria deserve to be studied for their ligninolytic potential.

  10. Polyanhydride degradation and erosion.

    Science.gov (United States)

    Göpferich, A; Tessmar, J

    2002-10-16

    It was the intention of this paper to give a survey on the degradation and erosion of polyanhydrides. Due to the multitude of polymers that have been synthesized in this class of material in recent years, it was not possible to discuss all polyanhydrides that have gained in significance based on their application. It was rather the intention to provide a broad picture on polyanhydride degradation and erosion based on the knowledge that we have from those polymers that have been intensively investigated. To reach this goal this review contains several sections. First, the foundation for an understanding of the nomenclature are laid by defining degradation and erosion which was deemed necessary because many different definitions exist in the current literature. Next, the properties of major classes of anhydrides are reviewed and the impact of geometry on degradation and erosion is discussed. A complicated issue is the control of drug release from degradable polymers. Therefore, the aspect of erosion-controlled release and drug stability inside polyanhydrides are discussed. Towards the end of the paper models are briefly reviewed that describe the erosion of polyanhydrides. Empirical models as well as Monte-Carlo-based approaches are described. Finally it is outlined how theoretical models can help to answer the question why polyanhydrides are surface eroding. A look at the microstructure and the results from these models lead to the conclusion that polyanhydrides are surface eroding due to their fast degradation. However they switch to bulk erosion once the device dimensions drop below a critical limit.

  11. Fibro-porous poliglecaprone/polycaprolactone conduits: synergistic effect of composition and in vitro degradation on mechanical properties.

    Science.gov (United States)

    Patel, Harsh N; Garcia, Roman; Schindler, Carrie; Dean, Derrick; Pogwizd, Steven M; Singh, Raj; Vohra, Yogesh K; Thomas, Vinoy

    2015-04-01

    Blends of poliglecaprone (PGC) and polycaprolactone (PCL) of varying compositions were electrospun into tubular conduits and their mechanical, morphological, thermal and in vitro degradation properties were evaluated under simulated physiological conditions. Generally, mechanical strength, modulus and hydrophilic nature were enhanced by the addition of PGC to PCL. An in vitro degradation study in phosphate-buffered saline (pH 7.3) was carried out for up to 1 month to understand the hydrolytic degradation effect on the mechanical properties in both the longitudinal and circumferential directions. Pure PCL and 4:1 PCL/PGC blend scaffolds exhibited considerable elastic stiffening after a 1 month in vitro degradation. Fourier transform infrared spectroscopic and DSC techniques were used to understand the degradation behavior and the changes in structure and crystallinity of the polymeric blends. A 3:1 PCL/PGC blend was concluded to be a judicious blend composition for tubular grafts based on overall results on the mechanical properties and performance after a 1 month in vitro degradation study.

  12. DDE remediation and degradation.

    Science.gov (United States)

    Thomas, John E; Ou, Li-Tse; All-Agely, Abid

    2008-01-01

    DDT and its metabolites, DDD and DDE, have been shown to be recalcitrant to degradation. The parent compound, DDT, was used extensively worldwide starting in 1939 and was banned in the United States in 1973. The daughter compound, DDE, may result from aerobic degradation, abiotic dehydrochlorination, or photochemical decomposition. DDE has also occurred as a contaminant in commercial-grade DDT. The p,p'-DDE isomer is more biologically active than the o,p-DDE, with a reported half-life of -5.7 years. However, when DDT was repeatedly applied to the soil, the DDE concentration may remain unchanged for more than 20 yr. Remediation of DDE-contaminated soil and water may be done by several techniques. Phytoremediation involves translocating DDT, DDD, and DDE from the soil into the plant, although some aquatic species (duckweed > elodea > parrot feather) can transform DDT into predominantly DDD with some DDE being formed. Of all the plants that can uptake DDE, Cucurbita pepo has been the most extensively studied, with translocation values approaching "hyperaccumulation" levels. Soil moisture, temperature, and plant density have all been documented as important factors in the uptake of DDE by Cucurbita pepo. Uptake may also be influenced positively by amendments such as biosurfactants, mycorrhizal inoculants, and low molecular weight organic acids (e.g., citric and oxalic acids). DDE microbial degradation by dehalogenases, dioxygenases, and hydrolases occurs under the proper conditions. Although several aerobic degradation pathways have been proposed, none has been fully verified. Very few aerobic pure cultures are capable of fully degrading DDE to CO2. Cometabolism of DDE by Pseudomonas sp., Alicaligens sp., and Terrabacter sp. grown on biphenyl has been reported; however, not all bacterial species that produce biphenyl dioxygenase degraded DDE. Arsenic and copper inhibit DDE degradation by aerobic microorganisms. Similarly, metal chelates such as EDTA inhibit the

  13. Drift Degradation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    D. Kicker

    2004-09-16

    Degradation of underground openings as a function of time is a natural and expected occurrence for any subsurface excavation. Over time, changes occur to both the stress condition and the strength of the rock mass due to several interacting factors. Once the factors contributing to degradation are characterized, the effects of drift degradation can typically be mitigated through appropriate design and maintenance of the ground support system. However, for the emplacement drifts of the geologic repository at Yucca Mountain, it is necessary to characterize drift degradation over a 10,000-year period, which is well beyond the functional period of the ground support system. This document provides an analysis of the amount of drift degradation anticipated in repository emplacement drifts for discrete events and time increments extending throughout the 10,000-year regulatory period for postclosure performance. This revision of the drift degradation analysis was developed to support the license application and fulfill specific agreement items between the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Department of Energy (DOE). The earlier versions of ''Drift Degradation Analysis'' (BSC 2001 [DIRS 156304]) relied primarily on the DRKBA numerical code, which provides for a probabilistic key-block assessment based on realistic fracture patterns determined from field mapping in the Exploratory Studies Facility (ESF) at Yucca Mountain. A key block is defined as a critical block in the surrounding rock mass of an excavation, which is removable and oriented in an unsafe manner such that it is likely to move into an opening unless support is provided. However, the use of the DRKBA code to determine potential rockfall data at the repository horizon during the postclosure period has several limitations: (1) The DRKBA code cannot explicitly apply dynamic loads due to seismic ground motion. (2) The DRKBA code cannot explicitly apply loads due to thermal

  14. Learning Curve in a Western Training Center of the Circumferential En Bloc Esophageal Endoscopic Submucosal Dissection in an In Vivo Animal Model

    Directory of Open Access Journals (Sweden)

    Miguel A. Tanimoto

    2011-01-01

    Full Text Available Aim. Evaluate the feasibility to overcome the learning curve in a western training center of the en bloc circumferential esophageal (ECE- ESD in an in vivo animal model. Methods. ECE-ESD was performed on ten canine models under general anesthesia on artificial lesions at the esophagus marked with coagulation points. After the ESD each canine model was euthanized and surgical resection of the esophagus and stomach was carried out according to “the Principles of Humane Experimental Technique, Russel and Burch.” The specimen was fixed with needles on cork submerged in formalin with the esophagus and stomach then delivered to the pathology department to be analyzed. Results. ECE-ESD was completed without complications in the last 3/10 animal models. Mean duration for the procedures was 192±35 minutes (range 140–235 minutes. All the procedures were done at the animal lab surgery room with cardio pulmonary monitoring and artificial ventilation by staff surgery members and a staff member of the Gastroenterology department trained during 1999–2001 at the Fujigaoka hospital of the Showa U. in Yokohama, Japan, length (range 15–18 mm and 51±6.99 width (range 40–60 mm. Conclusion. ECE-ESD training is feasible in canine models for postgraduate endoscopy fellows.

  15. Safety and effectiveness of a circumferential clip-based vascular closure device for hemostasis in off-label applications: Comparison with standard applications

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Chan; Kim, Chang Won [Dept. of Radiology, Pusan National University School of Medicine, Pusan National University Hospital, Busan (Korea, Republic of); Jeon, Ung Bae [Dept. of Radiology, Pusan National University School of Medicine, Yangsan Pusan National University Hospital, Yangsan (Korea, Republic of)

    2016-09-15

    We investigated the efficacy and safety of a circumferential nitinol clip based arterial closure device following arteriotomy, especially in off-label applications. Consecutive patients who underwent the procedure with arteriotomy from January 2011 to February 2014 were included in this study. We defined standard use as the use of StarClose for retrograde puncture of the common femoral artery (CFA) and off-label use as the use of StarClose for retrograde puncture of the superficial femoral artery (SFA), antegrade puncture of the CFA or SFA, puncture of the brachial artery or puncture of the vascular graft. The procedures performed included percutaneous transluminal angioplasty and thrombolysis. Technical success was defined as complete hemostasis achieved within 3 minute after the closure. Complications, and laboratory findings associated with coagulation function, were also investigated. There were 146 cases of standard applications and 111 cases of off-label applications. Technical success was achieved in all cases. The off-label group comprised the use of StarClose for retrograde puncture of the SFA (n = 19), antegrade puncture of the CFA or SFA (n = 74), brachial artery puncture (n = 5), larger sheath than 6 Fr (n = 7) and vascular graft puncture (n = 6). Minor complications were noted in both groups (standard group: 7.5%, off-label group: 2.7%). Off-label use of StarClose is safe and feasible.

  16. Learning Curve in a Western Training Center of the Circumferential En Bloc Esophageal Endoscopic Submucosal Dissection in an In Vivo Animal Model

    Science.gov (United States)

    Tanimoto, Miguel A.; Torres-Villalobos, Gonzalo; Fujita, Rikiya; Santillan-Doherty, Patricio; Albores-Saavedra, Jorge; Chable-Montero, Fredy; Martin-del-Campo, Luis A.; Vasquez, Lucia; Bravo-Reyna, Carlos; Villanueva, Octavio; Villalobos, Jose J.; Uribe, Misael; Valdovinos, Miguel A.

    2011-01-01

    Aim. Evaluate the feasibility to overcome the learning curve in a western training center of the en bloc circumferential esophageal (ECE-) ESD in an in vivo animal model. Methods. ECE-ESD was performed on ten canine models under general anesthesia on artificial lesions at the esophagus marked with coagulation points. After the ESD each canine model was euthanized and surgical resection of the esophagus and stomach was carried out according to “the Principles of Humane Experimental Technique, Russel and Burch.” The specimen was fixed with needles on cork submerged in formalin with the esophagus and stomach then delivered to the pathology department to be analyzed. Results. ECE-ESD was completed without complications in the last 3/10 animal models. Mean duration for the procedures was 192 ± 35 minutes (range 140–235 minutes). All the procedures were done at the animal lab surgery room with cardio pulmonary monitoring and artificial ventilation by staff surgery members and a staff member of the Gastroenterology department trained during 1999–2001 at the Fujigaoka hospital of the Showa U. in Yokohama, Japan, length (range 15–18 mm) and 51 ± 6.99 width (range 40–60 mm). Conclusion. ECE-ESD training is feasible in canine models for postgraduate endoscopy fellows. PMID:21976950

  17. Numerical Study on the Effect of Single Shallow Circumferential Groove Casing Treatment on the Flow Field and the Stability of a Transonic Compressor

    Directory of Open Access Journals (Sweden)

    Mohsen Agha Seyed Mirzabozorg

    2017-01-01

    Full Text Available The present research investigates the effect of the location and the width of single shallow circumferential groove casing treatment on the flow field and the stability improvement of NASA Rotor 37 utilizing the help of computational fluid dynamics. At first, steady state simulation of Rotor37 was presented for smooth casing (without groove. Then, forty five various grooved casing were simulated and compared with the smooth casing. The results indicated that narrow grooves had slight effect on the adiabatic efficiency but as the width of the groove was increased, a decline in efficiency was observed. The investigation on the stall margin revealed that narrow grooves next to the leading edge could improve the stall margin by a reduction in the size of vortex breakdown zone. Medium-width grooves displayed an effective role in delaying the separation- produced by shock wave and boundary layer interaction- on the blade suction side near the casing. This type of grooves could improve the stall margin more than narrow grooves when located on the top of separation zone near the blade suction side. Wide grooves had negative effect on the stall margin and caused a significant drop in the efficiency and the total pressure ratio of the compressor.

  18. Status report on a NDT round robin on austenitic circumferential pipe welds; Statusbericht zu einem ZfP-Ringversuch an austenitischen Rohrleitungs-Rundschweissnaehten

    Energy Technology Data Exchange (ETDEWEB)

    Hesselmann, W. [PreussenElektra AG, Hannover (Germany); Maier, H.J.; Knoch, P.; Mletzko, U. [MPA, Stuttgart (Germany)

    1996-12-31

    Since fall 1993, a study is performed at MPA Stuttgart in cooperation with the Czech Association of large power plant operators, on non-destructive evaluation of austenitic circumferential pipe welds. The status report presents the project concept and the current progress. The project tasks until now cover NDE of 15 welds. Results are given of ultrasonic tests carried out by 9 institutions, X-ray film evaluations by 23 individuals, and further examinations analysed in comparison to the destructive verification tests (metallography). (orig./MM) [Deutsch] Seit Herbst 1993 wird an der MPA Stuttgart in Zusammenarbeit mit der Technischen Vereinigung der Grosskraftwerksbetreiber e.V. (VGB) eine Untersuchung ueber die zerstoerungsfreie Pruefung (ZfP) von austenitischen Rohrleitungs-Rundschweissnaehten durchgefuehrt. Dieser Statusbericht zeigt die Konzeption und den gegenwaertigen Stand des Programms. Das Vorhaben umfasst bis jetzt zerstoerungsfreie Pruefungen an 15 Naehten. Berichtet wird ueber Ultraschall-Pruefungen durch 9 Institutionen, ueber Roentgenfilm-Auswertungen durch 23 Personen sowie ueber weitere Untersuchungen im Vergleich mit der vollstaendigen zerstoerenden Verifizierung (Metallografie). (orig./MM)

  19. Predictors of circumferential resection margin involvement in surgically resected rectal cancer: A retrospective review of 23,464 patients in the US National Cancer Database

    Science.gov (United States)

    Al-Sukhni, Eisar; Attwood, Kristopher; Gabriel, Emmanuel; Nurkin, Steven J.

    2017-01-01

    Introduction The circumferential resection margin (CRM) is a key prognostic factor after rectal cancer resection. We sought to identify factors associated with CRM involvement (CRM+). Methods A retrospective review was performed of the National Cancer Database, 2004–2011. Patients with rectal cancer who underwent radical resection and had a recorded CRM were included. Multivariable analysis of the association between clinicopathologic characteristics and CRM was performed. Tumor patients, 13.3% were CRM+. Factors associated with CRM+ were diagnosis later in the study period, lack of insurance, advanced stage, higher grade, undergoing APR, and receiving radiation. Nearly half of CRM+ patients did not receive neoadjuvant therapy. CRM+ patients who did not receive neoadjuvant therapy were more likely to be female, older, with more comorbidities, smaller tumors, earlier clinical stage, advanced pathologic stage, and CEA-negative disease compared to those who received it. Conclusions Factors associated with CRM+ include features of advanced disease, undergoing APR, and lack of health insurance. Half of CRM+ patients did not receive neoadjuvant treatment. These represent cases where CRM status may be modifiable with appropriate pre-operative selection and multidisciplinary management. PMID:26906328

  20. Modeling of guided circumferential SH and Lamb-type waves in open waveguides with semi-analytical finite element and Perfectly Matched Layer method

    Science.gov (United States)

    Matuszyk, Paweł J.

    2017-01-01

    The circumferential guided waves (CGW) are of increasing interest for non-destructive inspecting pipes or other cylindrical structures. If such structures are buried underground, these modes can also deliver some valuable information about the surrounding medium or the quality of the contact between the pipe and the embedding medium. Toward this goal, the detailed knowledge of the dispersive characteristics of CGW is required; henceforth, the robust numerical method has to be established, which allows for the extensive study of the propagation of these modes under different loading conditions. Mathematically, this is the problem of the propagation of guided waves in an open waveguide. This problem differs significantly from the corresponding problem of a closed waveguide both in physical and numerical aspect. The paper presents a combination of semi-analytical finite element method with Perfectly Matched Layer technique for a class of coupled acoustics/elasticity problems with application to modeling of CGW. We discuss different aspects of our algorithm and validate the proposed approach against other established methods available in the literature. The presented numerical examples positively verify the robustness of the proposed method.

  1. Geologic interpretations of seismic data Route 128 (Northern Circumferential Highway) cut, and Hopkins Street grade separation stations 1-18 in Wakefield, Mass.

    Science.gov (United States)

    May, James E.; Lineham, Rev. Daniel

    1950-01-01

    The completion of a segment of the Northern Circumferential Highway, Route 126, in Wakefield, Mass., requires an underpass bridge at Hopkins Street, Station 5+50. The plan of the project shows approximately 1800 feet if approach cuts between stations 1 and 18. In October 1945 a preliminary seismic study was made of a segment of this cut between stations 6+50 and 13+30. Four profiles were made at this time and a report was submitted by Newton E. Chute and Rev. Daniel Linhan (file report of January 15). This work showed a relatively shallow (in general, 6 to 12 feet in depth) somewhat irregular bedrock surface between stations 6+50 and 13+50. That data indicated that much of this segment of the cut will be in bedrock. In order to obtain more complete data for the preparation of detailed estimates on the amount of bedrock to be excavated for this segment of the cut, and also to obtain sufficient data for the unexplored segment of the cut, 21 additional seismic traverses were made in September 1949. The present report contains only the results obtained from this later work. The work was performed as a part of a cooperative program of the Massachusetts Department of Public Works and the United States Geological Survey.

  2. Mathematical treatment of melting and solidification of phase change materials between circumferentially finned tubes. Analytische Behandlung des Schmelzens und Erstarrens von Latentwaermespeichermaterialien in Rippenrohrgeometrien

    Energy Technology Data Exchange (ETDEWEB)

    Heinisch, M.

    1987-01-01

    The following study deals with the theoretical investigation of heat transfer in a latent heat store. The object of the investigation is a heat exchanger element with a circumferentially finned tube, in which the space between the fins is filled with storage material. An analytical method, employing Green's function, was developed for this arrangement in order to solve the two dimensional (r,z-coordinates) transient heat conduction in inhomogenous materials with simultaneous phase change. When compared with other well-known analytical methods, the most important advantages are that the Fourier heat conduction equation and the boundary conditions at the phase front are simultaneously fulfilled by the final solution, as well as the fact that the initial temperature is independent of a given phase change temperature. A fundamental advantage can also be seen in the very small number of time steps for calculating the transient charging/discharging processes and hence shorter calculation times. Two special extreme cases were designed where the results agree well with literature data. In comparison with the numerically calculated melting and solidification behaviour only small variations were observed.

  3. Motor degradation prediction methods

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, J.R.; Kelly, J.F.; Delzingaro, M.J.

    1996-12-01

    Motor Operated Valve (MOV) squirrel cage AC motor rotors are susceptible to degradation under certain conditions. Premature failure can result due to high humidity/temperature environments, high running load conditions, extended periods at locked rotor conditions (i.e. > 15 seconds) or exceeding the motor`s duty cycle by frequent starts or multiple valve stroking. Exposure to high heat and moisture due to packing leaks, pressure seal ring leakage or other causes can significantly accelerate the degradation. ComEd and Liberty Technologies have worked together to provide and validate a non-intrusive method using motor power diagnostics to evaluate MOV rotor condition and predict failure. These techniques have provided a quick, low radiation dose method to evaluate inaccessible motors, identify degradation and allow scheduled replacement of motors prior to catastrophic failures.

  4. Antifoam degradation testing

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, D. P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL); Zamecnik, J. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL); Newell, D. D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL); Williams, M. S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL)

    2015-08-20

    This report describes the results of testing to quantify the degradation products resulting from the dilution and storage of Antifoam 747. Antifoam degradation is of concern to the Defense Waste Processing Facility (DWPF) due to flammable decomposition products in the vapor phase of the Chemical Process Cell vessels, as well as the collection of flammable and organic species in the offgas condensate. The discovery that hexamethyldisiloxane is formed from the antifoam decomposition was the basis for a Potential Inadequacy in the Safety Analysis declaration by the DWPF.

  5. 管间界面特性对周向超声导波传播特性的影响∗%Influence of the interfacial prop erties on guided circumferential wave propagation in the circular tub e structure

    Institute of Scientific and Technical Information of China (English)

    高广健; 邓明晰; 李明亮; 刘畅

    2015-01-01

    The mathematical expressions both of displacement and stress fields of circumferential wave propagation in circular tube structure with a weak interface are derived on condition that the interfacial properties between the two circular tubes are characterized by the interfacial spring model. Based on the said displacement and stress expressions derived, the dispersion equation of ultrasonic guided circumferential wave (UGCW) modes is formally presented by using the corresponding mechanical boundary conditions. According to the technique of modal expansion analysis for waveguide excitation, for a given excitation source used to generate circumferential wave in circular tube structure, the corresponding field of circumferential wave propagation can be decomposed into a series of UGCW modes. Using the reciprocity relations and mode orthogonality, the analytical expression of UGCW mode expansion coefficient is derived, which is closely related to the given excitation source for UGCW generation and the interfacial properties between the two tubes. The influences of change in the interfacial property on dispersion and acoustic field of the UGCW propagation are numerically analyzed. In the cases of perfect and sliding interfaces, for a given UGCW mode, the relative change rate of phase velocity is defined, and then its curve versus frequency is calculated, through which the specific frequency can be determined where the UGCW phase velocity appears to be most sensitive to the change in the interfacial property. For a given UGCW mode and driving frequency, it is numerically found that the displacement field on the outside surface of the circular tube structure changes sensitively and monotonically with change in interfacial property between the tubes. Clearly, through choosing the appropriate driving frequency and the mode of UGCW propagation, both the UGCW phase velocity and the displacement field on the outside surface of the circular tube structure will be monotonic and

  6. Analysis of circumferential and longitudinal left ventricular systolic function in patients with non-ischemic chronic heart failure and preserved ejection fraction (from the CARRY-IN-HFpEF study).

    Science.gov (United States)

    Cioffi, Giovanni; Senni, Michele; Tarantini, Luigi; Faggiano, Pompilio; Rossi, Andrea; Stefenelli, Carlo; Russo, Tiziano Edoardo; Alessandro, Selmi; Furlanello, Francesco; de Simone, Giovanni

    2012-02-01

    Heart failure with preserved left ventricular ejection fraction (HFpEF) is implicitly attributed to diastolic dysfunction, often recognized in elderly patients with hypertension, diabetes, and renal dysfunction. In these patients, left ventricular circumferential and longitudinal shortening is often impaired despite normal ejection fraction. The aim of this prospective study was to analyze circumferential and longitudinal shortening and their relations in patients with nonischemic HFpEF. Stress-corrected midwall shortening (sc-MS) and mitral annular peak systolic velocity (S') were measured in 60 patients (mean age 73 ± 13 years) with chronic nonischemic HFpEF in stable New York Heart Association functional class II or III and compared to the values in 120 healthy controls and 120 patients with hypertension without HFpEF. Sc-MS was classified as low if HFpEF, 27% of patients with hypertension, and 2% of controls; isolated low S' was detected in 11% of patients with HFpEF, 7% of patients with hypertension, and 5% of controls; and combined low sc-MS and low S' was detected in 26% of patients with HFpEF, 9% of patients with hypertension, and 5% of controls (HFpEF vs others, all p values HFpEF. The relation between sc-MS and S' was nonlinear (cubic). Changes in S' within normal values corresponded to negligible variations in sc-MS, whereas the progressive decrease below 8.5 cm/s was associated with substantial decrease in sc-MS. In conclusion, circumferential and/or longitudinal systolic dysfunction is present in most patients with HFpEF. Circumferential shortening normalized by wall stress identifies more patients with concealed left ventricular systolic dysfunction than longitudinal shortening.

  7. Application of structural reliability to multi-circumferential cracking in steam generator tubes; Application de la fiabilite des structures a la multifissuration circonferentielle des tubes de generateur de vapeur

    Energy Technology Data Exchange (ETDEWEB)

    Ardillon, E.; Riffard, T. [Electricite de France (EDF), 78 - Chatou (France). Direction des Etudes et Recherches

    1997-12-31

    The COMPROMIS Code, developed by Electricite de France, is a probabilistic software tool concerned with assessment of probability of occurrence of a Steam Generator (SG) tube rupture caused by multi-circumferential cracking. It involves the calculation of low probabilities, for which Monte Carlo stratified sampling was selected. After a short description of the physical model, this paper presents the implementation of the numerical methods, some outputs of the code and sensitivity results of the rupture probability to input parameters. (author). 7 refs.

  8. Detection of pump degradation

    Energy Technology Data Exchange (ETDEWEB)

    Greene, R.H.; Casada, D.A.; Ayers, C.W. [and others

    1995-08-01

    This Phase II Nuclear Plant Aging Research study examines the methods of detecting pump degradation that are currently employed in domestic and overseas nuclear facilities. This report evaluates the criteria mandated by required pump testing at U.S. nuclear power plants and compares them to those features characteristic of state-of-the-art diagnostic programs and practices currently implemented by other major industries. Since the working condition of the pump driver is crucial to pump operability, a brief review of new applications of motor diagnostics is provided that highlights recent developments in this technology. The routine collection and analysis of spectral data is superior to all other technologies in its ability to accurately detect numerous types and causes of pump degradation. Existing ASME Code testing criteria do not require the evaluation of pump vibration spectra but instead overall vibration amplitude. The mechanical information discernible from vibration amplitude analysis is limited, and several cases of pump failure were not detected in their early stages by vibration monitoring. Since spectral analysis can provide a wealth of pertinent information concerning the mechanical condition of rotating machinery, its incorporation into ASME testing criteria could merit a relaxation in the monthly-to-quarterly testing schedules that seek to verify and assure pump operability. Pump drivers are not included in the current battery of testing. Operational problems thought to be caused by pump degradation were found to be the result of motor degradation. Recent advances in nonintrusive monitoring techniques have made motor diagnostics a viable technology for assessing motor operability. Motor current/power analysis can detect rotor bar degradation and ascertain ranges of hydraulically unstable operation for a particular pump and motor set. The concept of using motor current or power fluctuations as an indicator of pump hydraulic load stability is presented.

  9. Electroanatomical systems to guided circumferential pulmonary veins ablation for atrial fibrillation: initial experience from comparison between the Ensite/NavX and CARTO system

    Institute of Scientific and Technical Information of China (English)

    LIU Xu; WANG Xin-hua; GU Jia-ning; ZHOU Li; QIU Jian-hua

    2005-01-01

    Background The circumferential pulmonary vein ablation (CPVA) has been proved effective for atrial fibrillation (AF) treatment and is becoming more widely accepted and practiced. This study aims to evaluate the characteristics of the CARTO and the Ensite/NavX system and draw a comparison between them on the aspects of procedural parameters and clinical effectiveness.Methods Seventy-five cases with paroxysmal or chronic symptomatic AF were randomly assigned to CPVA procedure guided by the Ensite/NavX system (group Ⅰ, n=40) and by the CARTO system (group Ⅱ, n=35). After successful transseptal procedure, the geometry of left atrium was created under the guidance of the two systems. Radiofrequency energy was applied to circumferentially ablate tissues out of pulmonary veins' (PVs') ostia. In cases with chronic AF, linear ablation was applied to modify the substrate of left atrium (LA). The endpoint of the procedure was complete PVs isolation. Results Seventy-five cases underwent the procedure successfully. The total procedure and fluoroscopic durations in group Ⅱ were significantly shorter than in group Ⅰ [(150±23) min and (18±17) min versus (170±34) min and (25±16) min, P=0.03 and 0.04, respectively]. There was no significant difference in the fluoroscopic and procedure durations for geometry creation between group Ⅰ and group Ⅱ [(8±4) min and (16±11) min versus (5±4) min and (14±8) min, respectively]. The fluoroscopic durations for CPVA were (15±5) min in group Ⅰ versus (10±6) min in group Ⅱ (P=0.05), and the CPVA procedural durations were significantly shorter in group Ⅱ than in group Ⅰ [(18±11) min versus (25±10) min, P=0.04]. AF was terminated by radio frequency delivery in 14 cases (35%) in group Ⅰ versus 5 cases (14%) in group Ⅱ (P=0.035). After CPVA complete PV isolation was attained in 26 cases (65%) in group Ⅰ versus 11 cases (31%) in group Ⅱ (P=0.004). During a mean follow-up of 7 months, 32 (80%) cases in group

  10. A randomized prospective comparison of CartoMerge and CartoXP to guide circumferential pulmonary vein isolation for the treatment of paroxysmal atrial fibrillation

    Institute of Scientific and Technical Information of China (English)

    TANG Kai; MA Jian; ZHANG Shu; ZHANG Jing-ying; WEI Yi-dong; CHEN Yan-qing; YU Xue-jing; XU Ya-wei

    2008-01-01

    Background CartoXP and CartoMerge have been used to treat atrial fibrillation(AF)for several years.Our randomized prospective study compared clinical outcomes of these two versions of three dimensional electroanatomic mapping system in guiding catheter ablation for paroxysmal atrial fibrillation (PAF).Methods Eighty-one patients with symptomatic,drug refractory PAF were randomly assigned to CartoMerge group (n=42,mean age(54.5±13.1)years,history of AF=3.2 years)or CartoXP group(n=39,mean age(59.8±15.6)years,history of AF=2.9 years).All patients underwent 64-slice computed tomography(MSCT)1 to 3 days prior to ablation procedure.Using CartoMergeTM Image Integration Module,3D anatomical images of the left atrium(LA)and pulmonary veins(PVs)derived from MSCT of CartoMerge group were established and merged with the electroanatomical map.The integrated images were used to guide the procedure of circumferential pulmonary vein isolation (CPVI).In the other group,CPVI was guided just by CartoXP.The endpoint of CPVI in both groups was abolition or dissociation of pulmonary vein potentials(PVPs).Results Mapping points to establish the electroanatomical model of the LA/PVs were 48.7±13.4 in CartoMerge group and 62.5±15.7 in CartoXP group(P<0.001).Mean distance between mapping points and the MSCT surfaces in CartoMerge group was(1.59±0.33)mm.Accomplishment of abolition or dissociation of PVPs was achieved 95.2% in CartoMerge group and 92.3% in CartoXP group.Durations of procedure and exposure to X-ray were(156±25)minutes,(179±21)minutes(P<0.001) and(19.6±7.5)minutes,(28.5±12.8)minutes(P<0.001),respectively.After a follow-up with duration of(11.9±3.1)months vs (12.4±3.6)months post the first ablation procedure,patients free of AF were 33(78.6%)in CartoMerge group and 29(74.4%) in CartoXP group(P>0.50).No patient suffered pulmonary vein stenosis,alrioesophageal fistula,stroke or death.Conclusion Compared to CartoXP,CartoMerge shortened the catheter ablation

  11. Initial experience with circumferential pulmonary vein isolation guided by Overlay Ref and CartoMerge in the treatment of paroxysmal atrial fibrillation

    Institute of Scientific and Technical Information of China (English)

    TANG Kai; ZHAO Dong-dong; ZHANG Jing-ying; CHEN Yan-qing; XU Ya-wei

    2010-01-01

    Background CartoMerge has been widely used in guiding circumferential pulmonary vein isolation (CPVI) for the treatment of paroxysmal atrial fibrillation (PAF).However, the procedure of landmarks selection varies among operators according to their experience.Techniques have to be established to standardize this procedure.We propose that Overlay Ref could facilitate this procedure.This paper aimed to report our initial experience with CPVI guided by Overlay Ref and CartoMerge for the treatment of PAF.Methods Fifty-nine patients with PAF were enrolled in this study.Using Overlay Ref technique, a reference image (inverted) was faded into the live fluoroscopic image.Landmarks of CartoMerge were selected from anatomic points of the top of superior pulmonary veins (PVs) and the bottom of inferior PVs guided by Overlay Ref image.Overlay Ref images were also used to guide the ablation procedure combining with CartoMerge.Results All patients were successfully mapped by CartoMerge guided by Overlay Ref.The distance between the mapping points and the CT surfaces was (1.42±0.67) mm for the patients as a whole.This led to a successful rate of 96%for isolation of pulmonary veins.Duration of ablation procedure was (92±17) minutes.And the total duration of procedure was (139±32) minutes.CartoMerge could also be performed just with 3 paries to 4 paries selected landmarks guided by Overlay Ref without a full anatomic model constructed by Carto.Then, the total duration of procedure could be shortened to (115±38) minutes.Conclusions Overlay Ref technique can facilitate the catheter ablation of PAF and can help to standardize the procedure of landmarks selection.

  12. Distance between the rectal wall and mesorectal fascia measured by MRI: Effect of rectal distension and implications for preoperative prediction of a tumour-free circumferential resection margin

    Energy Technology Data Exchange (ETDEWEB)

    Slater, A. [Department of Specialist Radiology, University College Hospital, London (United Kingdom); Halligan, S. [Department of Specialist Radiology, University College Hospital, London (United Kingdom); Taylor, S.A. [Department of Specialist Radiology, University College Hospital, London (United Kingdom); Marshall, M. [Intestinal Imaging Centre, St Mark' s Hospital, Northwick Park, London (United Kingdom)

    2006-01-15

    Aim: To determine the effect of rectal distension, used by some workers to facilitate staging, on mesorectal tissues. Subjects and methods: Ninety-seven consecutive rectal cancer staging MRI examinations were identified of which 76 were analysable: 48 studies were performed using rectal insufflation of 100 ml room air and 28 were performed without distension. Median age was 69 and 72 years, respectively. In each patient a single experienced observer measured the distance from the outer rectal wall to the inner margin of the mesorectal fascia at four locations (12, 3, 6 and 9 o'clock), excluding sites of tumour involvement, from the T1-weighted axial image at the level of the sacro-coccygeal junction. The two groups of measurements were compared using Mann-Whitney test statistic, and frequencies then categorized into <5 mm or {>=}5 mm, and compared using Fisher's exact test. Results: The median distance between the rectal wall and mesorectal fascia in the distended group was approximately half that found in the non-distended group, and significantly lower at the 3, 6 and 9 o'clock positions (p<0.001). 68/167 (41%) of measurements were 5 mm or less, compared with 19/104 (18%) in the non-distended group (p<0.001). Conclusion: Rectal distension before MRI significantly reduces the distance between the rectal wall and mesorectal fascia. Although this is advocated to facilitate visualization of the primary tumour, it potentially affects the accuracy with which a clear circumferential resection margin can be predicted.

  13. N-acetylcysteine for the prevention of stricture after circumferential endoscopic submucosal dissection of the esophagus: a randomized trial in a porcine model

    Directory of Open Access Journals (Sweden)

    Barret Maximilien

    2012-05-01

    Full Text Available Abstract Background Circumferential endoscopic submucosal dissection (CESD of the esophagus would allow for both the eradication of Barrett’s esophagus and its related complications, such as advanced neoplasia. However, such procedures generally induce inflammatory repair resulting in a fibrotic stricture. N-acetylcysteine (NAC is an antioxidant that has shown some efficacy against pulmonary and hepatic fibrosis. The aim of our study was to evaluate the benefit of NAC in the prevention of esophageal cicatricial stricture after CESD in a swine model. Animals and methods Two groups of six pigs each were subjected to general anesthesia and CESD: after randomization, a first group received an oral NAC treatment regimen of 100 mg/kg/day, initiated one week before the procedure, whereas a second group was followed without any prophylactic treatment. Follow-up endoscopies took place seven, fourteen, twenty-one, and twenty-eight days after CESD. Necropsy, histological assessment of esophageal inflammation, and fibrosis were performed on day 28. Results The median esophageal lumen diameter on day 21 (main judgment criterion was 4 mm (range 2 to 5 in group 1 and 3 mm (range 1 to 7 in group 2 (P = 0.95. No significant difference was observed between the two groups regarding clinical evaluation (time before onset of clinically significant esophageal obstruction, number of dilations, esophageal inflammation and fibrosis, or oxidative stress damage on immunohistochemistry. Conclusions Despite its antioxidant effect, systemic administration of NAC did not show significant benefit on esophageal fibrosis in our animal model of esophageal wound healing within the experimental conditions of this study. Since the administered doses were relatively high, it seems unlikely that NAC might be a valuable option for the prevention of post-endoscopic esophageal stricture.

  14. 周向多爆炸成型弹丸战斗部仿真%Simulation Study of Circumferential MEFP Warhead

    Institute of Scientific and Technical Information of China (English)

    张利; 彭雪琴

    2014-01-01

    为了提高多爆炸成形弹丸(MEFP)对武装直升机、巡航导弹及空地制导武器等目标的毁伤能力,通过在炸药周向布置多个药型罩、轴向布置多层结构的办法,设计了一种新型多枚爆炸成形弹丸战斗部,分析了弹丸成型过程中的力学特性并利用动力学仿真软件模拟了成形过程。毁伤计算结果表明:该型战斗部所形成的单个EFP在穿透10 mm 装甲后仍具有较高的剩余动能,对轻型装甲目标具有较高的毁伤效能,研究结果可为小口径MEFP战斗部设计提供参考。%To strength the multiple explosively formed projectiles’(MEFP)damage effect on such targets like armed helicopters,cruise missiles and ground guided weapons,liners this paper designed were cir-cumferential layered with multi-layers along the axial.After the analysis on the EFP’s mechanical proper-ties during the forming process,the dynamic simulation software was adopted to reappear this forming process.De Marre formula calculation results show:the single EFP’s residual kinetic energy was signifi-cant even after it penetrated 10mm armor plate.The result of this paper indicates that MEFP warhead has impressive prospect to damage the abovementioned targets,and it will provide valuable reference for the Small-Caliber of the EFP’s warhead.

  15. Experimental investigation of extending stall-free mechanism of three-dimensional flow in circumferential skewed axial fans%周向弯曲叶片内部三维流动扩稳机理的实验研究

    Institute of Scientific and Technical Information of China (English)

    金光远; 欧阳华; 杜朝辉

    2013-01-01

    In this paper,the three-dimensional flow field at downstream of lower pressure axial fans with circumferential forward-skewed,backward-skewed blades are successfully measured using a hot-wire CTA system at off-design conditions.An X hot-wire probe is used to obtain three-dimensional velocity.Based on measurement results,the evolution of three-dimensional flow in these fans according to flow rate,and the effect of circumferential skewed blades on transporting of boundary layer at off-design conditions are discussed.The measurement results show that as flow rate decreases,three-dimensional flow structure is changed by circumferential skewed blades; the obvious suppression of passage flow is found near shroud and hub region,which is benefitial to improve stable operation range of circumferential skewed rotors; as centrifugal force increases,blade radial force Fr of circumferential forward-skewed blade has a positive effect on pressure gratitude,and seems to be efficient to control the velocity and direction of boundary layer movement.%对带有周向前弯和周向后弯叶片的低压轴流风机,采用双丝热线技术实验研究了周向弯曲叶片出口三维流动随流量降低变化规律.基于测量结果,详细阐述了周向弯曲叶片流道内三维流动结构的演化发展过程,分析非设计工况下叶片弯掠对流动的影响规律,结合径向平衡方程讨论了周向弯曲叶片对变工况边界层迁移的控制.结果表明:小流量工况下,周向弯曲叶片显著改变了流道内流动结构,且明显改善上下端壁区域的流通性,对于扩大稳定工作范围有着积极的作用;由于旋转离心力的增大,Fr对于径向压力梯度影响也发生变化,从而改变边界层的迁移方向和速度.

  16. Endocytic collagen degradation

    DEFF Research Database (Denmark)

    Madsen, Daniel H.; Jürgensen, Henrik J.; Ingvarsen, Signe;

    2012-01-01

    it crucially important to understand both the collagen synthesis and turnover mechanisms in this condition. Here we show that the endocytic collagen receptor, uPARAP/Endo180, is a major determinant in governing the balance between collagen deposition and degradation. Cirrhotic human livers displayed a marked......Fibrosis of the liver and its end-stage, cirrhosis, represent major health problems worldwide. In these fibrotic conditions, activated fibroblasts and hepatic stellate cells display a net deposition of collagen. This collagen deposition is a major factor leading to liver dysfunction, thus making...... up-regulation of uPARAP/Endo180 in activated fibroblasts and hepatic stellate cells located close to the collagen deposits. In a hepatic stellate cell line, uPARAP/Endo180 was shown to be active in, and required for, the uptake and intracellular degradation of collagen. To evaluate the functional...

  17. TALSPEAK Solvent Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Leigh R. Martin; Bruce J. Mincher

    2009-09-01

    Understanding the radiolytic degradation behavior of organic molecules involved in new or existing schemes for the recycle of used nuclear fuels is of significant interest for sustaining a closed nuclear fuel cycle. Here we have conducted several lines of investigation to begin understanding the effects of radiolysis on the aqueous phase of the TALSPEAK process for the separation of the trivalent lanthanides from the trivalent actinides. Using the 60-Co irradiator at the INL, we have begun to quantify the effects of radiation on the aqueous phase complexants used in this separation technique, and how this will affect the actinide lanthanide separation factor. In addition we have started to develop methodologies for stable product identification, a key element in determining the degradation pathways. We have also introduced a methodology to investigate the effects of alpha radiolysis that has previously received limited attention.

  18. Nylon separators. [thermal degradation

    Science.gov (United States)

    Lim, H. S.

    1977-01-01

    A nylon separator was placed in a flooded condition in K0H solution and heated at various high temperatures ranging from 60 C to 110 C. The weight decrease was measured and the molecular weight and decomposition product were analyzed to determine: (1) the effect of K0H concentration on the hydrolysis rate; (2) the effect of K0H concentration on nylon degradation; (3) the activation energy at different K0H concentrations; and (4) the effect of oxygen on nylon degradation. The nylon hydrolysis rate is shown to increase as K0H concentration is decreased 34%, giving a maximum rate at about 16%. Separator hydrolysis is confirmed by molecular weight decrease in age of the batteries, and the reaction of nylon with molecular oxygen is probably negligible, compared to hydrolysis. The extrapolated rate value from the high temperature experiment correlates well with experimental values at 35 degrees.

  19. Detection of pump degradation

    Energy Technology Data Exchange (ETDEWEB)

    Casada, D. [Oak Ridge National Lab., TN (United States)

    1995-04-01

    There are a variety of stressors that can affect the operation of centrifugal pumps. Although these general stressors are active in essentially all centrifugal pumps, the stressor level and the extent of wear and degradation can vary greatly. Parameters that affect the extent of stressor activity are manifold. In order to assure the long-term operational readiness of a pump, it is important to both understand the nature and magnitude of the specific degradation mechanisms and to monitor the performance of the pump. The most commonly applied method of monitoring the condition of not only pumps, but rotating machinery in general, is vibration analysis. Periodic or continuous special vibration analysis is a cornerstone of most pump monitoring programs. In the nuclear industry, non-spectral vibration monitoring of safety-related pumps is performed in accordance with the ASME code. Pump head and flow rate are also monitored, per code requirements. Although vibration analysis has dominated the condition monitoring field for many years, there are other measures that have been historically used to help understand pump condition; advances in historically applied technologies and developing technologies offer improved monitoring capabilities. The capabilities of several technologies (including vibration analysis, dynamic pressure analysis, and motor power analysis) to detect the presence and magnitude of both stressors and resultant degradation are discussed.

  20. Biogeochemical Cycles in Degraded Lands

    Science.gov (United States)

    Davidson, Eric A.; Vieira, Ima Celia G.; ReisdeCarvalho, Claudio Jose; DeanedeAbreuSa, Tatiana; deSouzaMoutinho, Paulo R.; Figueiredo, Ricardo O.; Stone, Thomas A.

    2004-01-01

    The objectives of this project were to define and describe the types of landscapes that fall under the broad category of "degraded lands" and to study biogeochemical cycles across this range of degradation found in secondary forests. We define degraded land as that which has lost part of its capacity of renovation of a productive ecosystem, either in the context of agroecosystems or as native communities of vegetation. This definition of degradation permits evaluation of biogeochemical constraints to future land uses.

  1. Circumferential ′ Woolly Hair Naevus

    Directory of Open Access Journals (Sweden)

    Thadeus J

    1998-01-01

    Full Text Available Woolly hair naevus presents as a circumscribed area of tightly coiled hair since birth, in an individual of non-negroid origin. We report a 10 year old boy of Indian origin who presented with woolly hair in the periphery of the scalp and normal straight hair in the center-mimicking a straight hair naevus.

  2. Ordered bulk degradation via autophagy

    DEFF Research Database (Denmark)

    Dengjel, Jörn; Kristensen, Anders Riis; Andersen, Jens S

    2008-01-01

    at proteasomal and lysosomal degradation ample cross-talk between the two degradation pathways became evident. Degradation via autophagy appeared to be ordered and regulated at the protein complex/organelle level. This raises several important questions such as: can macroautophagy itself be specific and what...

  3. Bacterial degradation of detergent compounds.

    Science.gov (United States)

    Goodnow, R A; Harrison, A P

    1972-10-01

    A survey for surfactant degradation among aerobic bacteria has been undertaken. Tests have been made in peptone medium where such a degradation, if it occurs, will be gratuitous. Tallow-alkyl-sulfate, alkyl-ethoxylate-sulfate, and linear-alkyl-benzene-sulfonate were used. Forty-five strains of 34 species in 19 genera degrade one or more of these detergent compounds. With some species, the surfactant inhibits degradation without inhibiting growth, whereas with one species slight degradation took place even at a toxic concentration of surfactant.

  4. Bacterial Degradation of Pesticides

    DEFF Research Database (Denmark)

    Knudsen, Berith Elkær

    This PhD project was carried out as part of the Microbial Remediation of Contaminated Soil and Water Resources (MIRESOWA) project, funded by the Danish Council for Strategic Research (grant number 2104-08-0012). The environment is contaminated with various xenobiotic compounds e.g. pesticides......D student, to construct fungal-bacterial consortia in order to potentially stimulate pesticide degradation thereby increasing the chance of successful bioaugmentation. The results of the project are reported in three article manuscripts, included in this thesis. In manuscript I, the mineralization of 2...

  5. Photothermal degradation studies

    Science.gov (United States)

    Liang, R. H.

    1985-01-01

    Key reaction intermediates of photooxidation identified and characterized by laser flash Electron Spin Resonance (ESR) spectroscopy were discussed. Effects of temperature and ultraviolet intensity were studied in order to develop meaningful accelerated testing procedures for encapsulant evaluation. In a program to study the failure of Tedlar/ethylene vinyl acetate (EVA)/stainless steel modules, failure modes similar to those observed outdoors in real-time conditions were simulated in accelerated testing. An experimental technique was developed to quantitatively assess the extent of degradation.

  6. Rat myocardial protein degradation.

    Science.gov (United States)

    Steer, J H; Hopkins, B E

    1981-07-01

    1. Myocardial protein degradation rates were determined by following tyrosine release from rat isolated left hemi-atria in vitro. 2. After two 20 min preincubations the rate of tyrosine release from hemi-atria was constant for 4 h. 3. Skeletal muscle protein degradation was determined by following tyrosine release from rat isolated hemi-diaphragm (Fulks, Li & Goldberg, 1975). 4. Insulin (10(-7) M) inhibited tyrosine release from hemi-atria and hemi-diaphragm to a similar extent. A 48 h fast increased tyrosine release rate from hemi-diaphragm and decreased tyrosine release rate from hemi-atria. Hemi-diaphragm tyrosine release was inhibited by 15 mmol/l D-glucose but a variety of concentrations of D-glucose (0, 5, 15 mmol/l) had no effect on tyrosine release from hemi-atria. Five times the normal plasma levels of the branched-chain amino acids leucine, isoleucine and valine had no effect on tyrosine release from either hemi-atria or hemi-diaphragm.

  7. Clinical study of microsplint and circumferential wiring in the treatment of mandibular body fracture in children%微型夹板配合环颌结扎治疗儿童下颌体部骨折的研究

    Institute of Scientific and Technical Information of China (English)

    姜刚勇

    2015-01-01

    目的:探讨微型夹板配合环颌结扎固定在儿童下颌骨体部骨折治疗中的应用。方法:选择2009~2012年儿童下颌体部骨折23例,采用微型夹板配合环颌结扎固定,观察其疗效。结果:微型夹板配合环颌结扎固定方法对儿童下颌骨骨折进行治疗具有不损伤恒牙胚,骨折复位良好、固定稳固、不影响进食,便于口腔清洁的特点。结论:微型夹板配合环颌结扎固定是治疗儿童下颌骨体部骨折的有效方法。%Objective:To evaluate the application of microsplint and circumferential wiring in the treatment of mandibular body frac-ture in children.Methods:23 children with mandibular body fracture were treated by microsplint and circumferential wiring from 2009 to 2012,the effects of treatment were assessed.Results:Treatment with microsplint and circumferential wiring did not injure perma-nent teeth germ.It showed many features,such as easy reduction of fractured bone segments,stable fixation,without interfere with eat-ing and benefit of mouth clearness.Conclusion:Microsplin and cicumferential wiring is effective for the treatment of mandibular body fracture in children.

  8. Thermal battery degradation mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Missert, Nancy A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brunke, Lyle Brent [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    Diffuse reflectance IR spectroscopy (DRIFTS) was used to investigate the effect of accelerated aging on LiSi based anodes in simulated MC3816 batteries. DRIFTS spectra showed that the oxygen, carbonate, hydroxide and sulfur content of the anodes changes with aging times and temperatures, but not in a monotonic fashion that could be correlated to phase evolution. Bands associated with sulfur species were only observed in anodes taken from batteries aged in wet environments, providing further evidence for a reaction pathway facilitated by H2S transport from the cathode, through the separator, to the anode. Loss of battery capacity with accelerated aging in wet environments was correlated to loss of FeS2 in the catholyte pellets, suggesting that the major contribution to battery performance degradation results from loss of active cathode material.

  9. DEGRADATION OF SHAPE MEMORY EFFECT

    OpenAIRE

    VanderMeer, R.

    1982-01-01

    An important parameter for deciding whether or not a SME alloy is suitable for practical applications is the magnitude of the strain reversa1 accompanying martensite reversion. This research is concerned with elucidating metallurgical factors that cause degradation of this heat-activated recovery strain, ER. After explaining what is meant by degradation, two manifestations of degradation recently identified in near-monotectoid uranium-niobium alloys will be described. The first was associated...

  10. Aerobic degradation of polychlorinated biphenyls

    Energy Technology Data Exchange (ETDEWEB)

    Pieper, D.H. [Dept. of Environmental Microbiology, German Research Center for Biotechnology, Braunschweig (Germany)

    2005-04-01

    The microbial degradation of polychlorinated biphenyls (PCBs) has been extensively studied in recent years. The genetic organization of biphenyl catabolic genes has been elucidated in various groups of microorganisms, their structures have been analyzed with respect to their evolutionary relationships, and new information on mobile elements has become available. Key enzymes, specifically biphenyl 2,3-dioxygenases, have been intensively characterized, structure/sequence relationships have been determined and enzymes optimized for PCB transformation. However, due to the complex metabolic network responsible for PCB degradation, optimizing degradation by single bacterial species is necessarily limited. As PCBs are usually not mineralized by biphenyl-degrading organisms, and cometabolism can result in the formation of toxic metabolites, the degradation of chlorobenzoates has received special attention. A broad set of bacterial strategies to degrade chlorobenzoates has recently been elucidated, including new pathways for the degradation of chlorocatechols as central intermediates of various chloroaromatic catabolic pathways. To optimize PCB degradation in the environment beyond these metabolic limitations, enhancing degradation in the rhizosphere has been suggested, in addition to the application of surfactants to overcome bioavailability barriers. However, further research is necessary to understand the complex interactions between soil/sediment, pollutant, surfactant and microorganisms in different environments. (orig.)

  11. Transcellular degradation of axonal mitochondria.

    Science.gov (United States)

    Davis, Chung-ha O; Kim, Keun-Young; Bushong, Eric A; Mills, Elizabeth A; Boassa, Daniela; Shih, Tiffany; Kinebuchi, Mira; Phan, Sebastien; Zhou, Yi; Bihlmeyer, Nathan A; Nguyen, Judy V; Jin, Yunju; Ellisman, Mark H; Marsh-Armstrong, Nicholas

    2014-07-01

    It is generally accepted that healthy cells degrade their own mitochondria. Here, we report that retinal ganglion cell axons of WT mice shed mitochondria at the optic nerve head (ONH), and that these mitochondria are internalized and degraded by adjacent astrocytes. EM demonstrates that mitochondria are shed through formation of large protrusions that originate from otherwise healthy axons. A virally introduced tandem fluorophore protein reporter of acidified mitochondria reveals that acidified axonal mitochondria originating from the retinal ganglion cell are associated with lysosomes within columns of astrocytes in the ONH. According to this reporter, a greater proportion of retinal ganglion cell mitochondria are degraded at the ONH than in the ganglion cell soma. Consistently, analyses of degrading DNA reveal extensive mtDNA degradation within the optic nerve astrocytes, some of which comes from retinal ganglion cell axons. Together, these results demonstrate that surprisingly large proportions of retinal ganglion cell axonal mitochondria are normally degraded by the astrocytes of the ONH. This transcellular degradation of mitochondria, or transmitophagy, likely occurs elsewhere in the CNS, because structurally similar accumulations of degrading mitochondria are also found along neurites in superficial layers of the cerebral cortex. Thus, the general assumption that neurons or other cells necessarily degrade their own mitochondria should be reconsidered.

  12. Contribution of ethylamine degrading bacteria to atrazine degradation in soils.

    Science.gov (United States)

    Smith, Daniel; Crowley, David E

    2006-11-01

    Bacterial communities that cooperatively degrade atrazine commonly consist of diverse species in which the genes for atrazine dechlorination and dealkylation are variously distributed among different species. Normally, the first step in degradation of atrazine involves dechlorination mediated by atzA, followed by stepwise dealkylation to yield either N-ethylammelide or N-isopropylammelide. As the liberated alkylamine moieties are constituents of many organic molecules other than atrazine, it is possible that a large number of alkylamine-degrading bacteria other than those previously described might contribute to this key step in atrazine degradation. To examine this hypothesis, we isolated 82 bacterial strains from soil by plating soil water extracts on agar media with ethylamine as a sole carbon source. Among the relatively large number of isolates, only 3 were able to degrade N-ethylammelide, and in each case were shown to carry the atzB gene and atzC genes. The isolates, identified as Rhizobium leguminosarum, Flavobacterium sp., and Arthrobacter sp., were all readily substituted into an atrazine-degrading consortium to carry out N-ethylammelide degradation. The distribution of these genes among many different species in the soil microbial population suggests that these genes are highly mobile and over time may lead to generation of various atrazine-degrading consortia.

  13. Research of Isolation and Degradation Conditions of Petroleum Degrading Marine

    Science.gov (United States)

    Fangrui, Guo

    2017-01-01

    A novel petroleum-degrading microbial strain was isolated from sediment samples in estuary of Bohai Sea estuary beaches. The strain was primarily identified as Alcanivorax sp. and named Alcanivorax sp. H34. Effect of PH values, temperature, nitrogen and phosphorus concentrations on degradation of H34 were investigated. The paraffinic components average degradation rate of H34 ungrowth cells under optimized conditions was studied. The results showed that the optimal growth conditions of H34 are were temperature of 30°C, initial PH of 7.0, nitrogen concentration of 3g/L, phosphorus concentration of 3g/L, and paraffinic components average degradation rates of H34 ungrowth cells was 41.6%, while total degradation rate was 45.5%.

  14. ASSAYING OF AUTOPHAGIC PROTEIN DEGRADATION

    NARCIS (Netherlands)

    C. Bauvy; A.J. Meijer; P. Codogno

    2009-01-01

    Macroautophagy is a three-step process: (1) autophagosomes form and mature, (2) the autophagosomes fuse with lysosomes, and (3) the autophagic cargo is degraded in the lysosomes. It is this lysosomal degradation of the autophagic cargo that constitutes the autophagic flux. As in the case of metaboli

  15. Experimental Investigation of Unsteady Flow in Circumferential Skewed Axial Fans at Off-design Conditions%叶片弯掠轴流风扇内瞬态流动的试验研究

    Institute of Scientific and Technical Information of China (English)

    金光远; 欧阳华; 杜朝辉

    2013-01-01

    对带有周向前弯和周向后弯叶片的低压轴流风扇,采用NI采集平台和双丝热线采集单元相结合的测量技术试验研究非设计工况下周向弯曲叶片的内部不稳定流动发展规律.对若干工况叶轮进出口三维流场进行详细测量,基于测量结果分析轴向、周向和径向方向的平均速度及湍流脉动速度,获得叶片周向弯曲叶轮内变工况下瞬态流场特性;通过对湍流度、雷诺应力和速度频谱分析,考察非设计工况下叶片周向弯曲叶轮固有的瞬态特性影响,分析进口来流扰动特征.研究结果显示NI采集平台和双丝热线采集单元整合的试验测量系统,成功测量低压周向弯曲叶轮变工况下的进出口三维流场,为多场同步测量提供技术参考;变工况下弯掠叶片对上下端壁区的不稳定流动具有显著的抑制作用,对于扩大稳定工作范围有着积极的作用;进口来流较高的湍流度主要存在近上下端壁区域,周向弯曲叶片对来流湍流度的影响主要集中在这两个区域;这些扰动主要集中于低频段,并呈宽频特性.%The unsteady characteristic of the inner flow to lower pressure axial fans with circumferential forward-skewed blades, backward-skewed blades is investigated experimentally at off-design conditions. The unsteady three-dimensional flow in circumferential skewed rotors upstream and downstream according to flow rates is successfully measured with a NI data collection platform and a hot-wire CTA unit (with a X probe). Based on the measurement results, axial, circumferential and radial components of the averaged velocity and turbulent velocity are analyzed to obtain the aerodynamic performance of circumferential skewed rotors; and the turbulent intensity, Reynold tensor and velocity spectrum are discussed to investigate the intrinsic unsteady flow in these rotors. The results show that the three-dimensional flow is captured by this measure system

  16. Degradation of carbofuran by ozonation.

    Science.gov (United States)

    Suneethi, S; Joseph, Kurian

    2009-04-01

    Degradation of commercial grade carbofuran (2, 3 dihydro-2, 2-dimethyl-7 benzo furanyl-N-methyl carbamate) in aqueous solution by ozone oxidation was investigated using bench scale experiments. The degradation rate was strongly influenced by the ozone dosage, pH, initial concentration of carbofuran and contact time of ozonation. Carbofuran solution of 200ppm concentration was degraded by 79% within 10 minutes consuming 87 mg of ozone at pH 4. The associated TOC reduction was observed to be 53%. Ammonium (20 mg/L) and nitrate (30 mg/L) ions were detected in the effluent as degradation products of ozonation. The results support the effectiveness of ozonation for degradation of organic pesticides such as carbofuran.

  17. Bacterial degradation of aminopyrine.

    Science.gov (United States)

    Blecher, H; Blecher, R; Wegst, W; Eberspaecher, J; Lingens, F

    1981-11-01

    1. Four strains of bacteria growing with aminopyrine as sole source of carbon were isolated from soil and were identified as strains of Phenylobacterium immobilis. 2. Strain M13 and strain E, the type species of Phenylobacterium immobilis (DSM 1986), which had been isolated by enrichment with chloridazon (5-amino-4-chloro-2-phenyl-2H-pyridazin-3-one) were used to investigate the bacterial degradation of aminopyrine. 3. Three metabolites were isolated and identified as: 4-(dimethylamino)-1,2-dihydro-1,5-dimethyl-2-(2,3-dihydro-2,3-dihydroxy-4,6-cyc lohexadien-1-yl)-3H-pyrazol-3-one, 4-(dimethylamino)-1,2-dihydro-1,5-dimethyl-2-(2,3-dihydroxyphenyl)-3H-pyrazol-3 -one and 4-(dimethylamino)-1,2-dihydro-1,5-dimethyl-3H-pyrazol-3-one. 4. An enzyme extract from cells of strain m13 was shown to further metabolize the catechol derivative of aminopyrine, with the formation of 2-pyrone-6-carboxylic acid. 5. Results indicate that the benzene ring of aminopyrine is the principal site of microbial metabolism.

  18. Enzymatic degradation of endomorphins.

    Science.gov (United States)

    Janecka, Anna; Staniszewska, Renata; Gach, Katarzyna; Fichna, Jakub

    2008-11-01

    Centrally acting plant opiates, such as morphine, are the most frequently used analgesics for the relief of severe pain, even though their undesired side effects are serious limitation to their usefulness. The search for new therapeutics that could replace morphine has been mainly focused on the development of peptide analogs or peptidomimetics with high selectivity for one receptor type and high bioavailability, that is good blood-brain barrier permeability and enzymatic stability. Drugs, in order to be effective, must be able to reach the target tissue and to remain metabolically stable to produce the desired effects. The study of naturally occurring peptides provides a rational and powerful approach in the design of peptide therapeutics. Endogenous opioid peptides, endomorphin-1 and endomorphin-2, are two potent and highly selective mu-opioid receptor agonists, discovered only a decade ago, which display potent analgesic activity. However, extensive studies on the possible use of endomorphins as analgesics instead of morphine met with failure due to their instability. This review deals with the recent investigations that allowed determine degradation pathways of endomorphins in vitro and in vivo and propose modifications that will lead to more stable analogs.

  19. Influence of pH on Morphology and Structure during Hydrolytic Degradation of the Segmented GL-b-[GL-co-TMC-co-CL]-b-GL Copolymer

    Directory of Open Access Journals (Sweden)

    Yolanda Márquez

    2015-09-01

    Full Text Available Hydrolytic degradation in media having a continuous variation of pH from 2 to 12 was studied for a copolymer having two polyglycolide hard blocks and a middle soft segment constituted by glycolide, trimethylene carbonate, and ɛ-caprolactone units. The last units were susceptible to cross-linking reactions by γ irradiation that led to an increase of the molecular weight of the sample. Nevertheless, the susceptibility to hydrolytic degradation was enhanced with respect to non-irradiated samples and consequently such samples were selected to analyze the degradation process through weight loss measurements and the evaluation of changes on molecular weight, morphology, and SAXS patterns. Results reflected the different hydrolytic mechanisms that took place in acid and basic media and the different solubilization of the degradation products. Thus, degradation was faster and solubilization higher in the basic media. In this case, fibers showed a high surface erosion and the formation of both longitudinal and deep circumferential cracks that contrasted with the peeling process detected at intermediate pHs (from 6 to 8 and the absence of longitudinal cracks at low pHs. SAXS measurements indicated that degradation was initiated through the hydrolysis of the irregular molecular folds placed on the amorphous interlamellar domains but also affected lamellar crystals at the last stages. Subsequent heating processes performed with degraded samples were fundamental to reveal the changes in microstructure that occurred during degradation and even the initial lamellar arrangement. In particular, the presence of interfibrillar domains and the disposition of lamellar domains at different levels along the fiber axis for a determined cross-section were evidenced.

  20. Photoassisted Fenton degradation of polystyrene.

    Science.gov (United States)

    Feng, Hui-Min; Zheng, Jia-Chuan; Lei, Ngai-Yu; Yu, Lei; Kong, Karen Hoi-Kuan; Yu, Han-Qing; Lau, Tai-Chu; Lam, Michael H W

    2011-01-15

    Fenton and photoassisted Fenton degradation of ordinary hydrophobic cross-linked polystyrene microspheres and sulfonated polystyrene beads (DOWEX 50WX8) have been attempted. While the Fenton process was not able to degrade these polystyrene materials, photoassisted Fenton reaction (mediated by broad-band UV irradiation from a 250 W Hg(Xe) light source) was found to be efficient in mineralizing cross-linked sulfonated polystyrene materials. The optimal loadings of the Fe(III) catalyst and the H(2)O(2) oxidant for such a photoassisted Fenton degradation were found to be 42 μmol-Fe(III) and 14.1 mmol-H(2)O(2) per gram of the sulfonated polystyrene material. The initial pH for the degradation was set at pH 2.0. This photoassisted Fenton degradation process was also able to mineralize commonly encountered polystyrene wastes. After a simple sulfonation pretreatment, a mineralization efficiency of >99% (by net polymer weight) was achieved within 250 min. The mechanism of this advanced oxidative degradation process was investigated. Sulfonate groups introduced to the surface of the treated polystyrene polymer chains were capable of rapidly binding the cationic Fe(III) catalyst, probably via a cation-exchange mechanism. Such a sorption of the photoassisted Fenton catalyst was crucial to the heterogeneous degradation process.

  1. Performance Degradation of LSCF Cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Alinger, Matthew

    2013-09-30

    This final report summarizes the progress made during the October 1, 2008 - September 30, 2013 period under Cooperative Agreement DE-NT0004109 for the U. S. Department of Energy/National Energy Technology Laboratory (USDOE/NETL) entitled “Performance Degradation of LSCF Cathodes”. The primary objective of this program is to develop a performance degradation mitigation path for high performing, cost-effective solid oxide fuel cells (SOFCs). Strategies to mitigate performance degradation are developed and implemented. In addition, thermal spray manufacturing of SOFCs is explored. Combined, this work establishes a basis for cost-effective SOFC cells.

  2. 牙龈环切辅助牙周炎患牙正畸压入的效果观察%Effect of periodontitis involved teeth intrusion after circumferential supracrestal fibrotomy

    Institute of Scientific and Technical Information of China (English)

    袁建桥; 张月兰; 刘林嶓; 蔡留意; 张志伟

    2013-01-01

    Aim:To investigate the effect of intrusion of the teeth at the aligning and leveling stage after circumferen -tial supracrestal fibrotomy.Methods:During aligning and leveling stage of orthodontic therapy , 34 teeth with attachment loss were treated based on circumferential supracrestal fibrotomy .Parallel periapical radiographic technique was used to measure changes in crown-root ratio and cemento-enamel junction and alveolar crest height before and after treatment .Re-sults: The aligning and leveling stage of the orthodontic treatment with circumferential supracrestal fibrotomy spent 6-9 months.The overjet was improved ,the overbite became normal, the curve of spee was decreased ,and the periodontal health maintained as well.Specifically, the average amount of intrusion into the bone was about (0.73 ±0.56) mm, and crown-root ratio was improved by (13 ±12)%.Conclusion: The orthodontic treatment with circumferential supracrestal fibrotomy and the teeth intrusion is helpful for prognosis of periodontitis.%目的:探讨牙龈环切辅助牙周炎患牙正畸压低对牙周炎患牙预后的影响.方法:选取34颗伴有附着丧失的牙周炎患牙,牙周基础治疗后开展正畸治疗,在排齐整平阶段配合牙龈环切术,治疗前后使用平行投照根尖片来测量牙冠和牙根比例的变化以及釉牙骨质界-牙槽嵴顶高度的变化量.结果:牙龈环切辅助正畸经过6~9个月完成排齐整平,患牙覆盖改善,覆牙合正常,牙弓spee曲线减小,牙龈无红肿,牙周袋无加深,无明显探诊出血.患牙平均被压入(0.73±0.56)mm,冠根比例改善了(13±12)%.结论:牙龈环切术辅助牙周炎的正畸压入治疗有利于牙周炎的预后.

  3. 变工况下周向弯曲风扇叶顶涡声特性%Research of Aerodynamic Noise Source in Tip Region of Axial Fans with Circumferential Skewed Blades at Off-Design Conditions

    Institute of Scientific and Technical Information of China (English)

    金光远; 欧阳华; 胡彬彬; 吴亚东; 杜朝辉

    2011-01-01

    Aerodynamic noise source generated by tip leakage flow in circumferential skewed axial fans was studied by CFD simulation and experiments under off-design conditions. Relationship between tip leakage flow and aerodynamic noise was analyzed based on vortex-sound theory of low speed homentropic flow. Synergy between acoustic source and tip leakage vortex was discussed. Pressure test on casing wall and acoustic far field test were conducted to find how the different circumferential skewed direction control acoustic characteristics. The results show that the acoustic source generated by tip leakage vortex of circumferential skewed blades is an important noise source under off-design conditions. The angle between velocity vector and vortex vector controls the strength and the distribution of the acoustic source in tip clearance region. The acoustic source in tip clearance region is related with the acoustic far field under off-design conditions.%采用计算流体力学数值方法研究变工况下周向弯曲低压轴流风扇的叶顶泄漏流动特性,结合涡声理论分析泄漏涡与声源的协同特性,分析叶片不同周向弯曲方向对协同性的影响,并通过近场机匣壁面动态压力测量和远场声学测量,验证叶片周向弯曲方向对近远场声学特性的控制规律.研究表明,泄漏涡声源是周向弯曲叶轮小流量工况下的重要声源,速度矢量与涡矢量的夹角值控制叶顶区域声源强度和分布.近远场实验结果表明,泄漏涡声源与远场声学关系密切.

  4. Bacterial isolates degrading aliphatic polycarbonates.

    Science.gov (United States)

    Suyama, T; Hosoya, H; Tokiwa, Y

    1998-04-15

    Bacteria that degrade an aliphatic polycarbonate, poly(hexamethylene carbonate), were isolated from river water in Ibaraki. Prefecture, Japan, after enrichment in liquid medium containing poly(hexamethylene carbonate) suspensions as carbon source, and dilution to single cells. Four of the strains, 35L, WFF52, 61A and 61B2, degraded poly(hexamethylene carbonate) on agar plate containing suspended poly(hexamethylene carbonate). Degradation of poly(hexamethylene carbonate) was confirmed by gel permeation chromatography. Besides poly(hexamethylene carbonate), the strains were found to degrade poly(tetramethylene carbonate). The strains were characterized morphologically, physiologically, and by 16S rDNA sequence analysis. Strains 35L and WFF52 were tentatively identified as Pseudomonas sp. and Variovorax sp., respectively, while strains 61A and 61B2 constitute an unidentified branch within the beta subclass of the Proteobacteria.

  5. Ecosystemic approaches to land degradation

    Energy Technology Data Exchange (ETDEWEB)

    Puigdefabregas, J.; Barrio, G. del; Hill, J.

    2009-07-01

    Land degradation is recognized as the main outcome of desertification. However available procedures for its assessment are still unsatisfactory because are often too costly for surveying large areas and rely on specific components of the degradation process without being able to integrate them in a unique process. One of the objectives of De Survey project is designing and implementing operational procedures for desertification surveillance, including land degradation. A strategic report was compiled and reproduced here for selecting the most appropriate approaches to the project conditions. The report focuses on using attributes of ecosystem maturity as a natural way to integrate the different drivers of land degradation in simple indices. The review surveys different families of attributes concerned with water and energy fluxes through the ecosystem, its capacity to sustain biomass and net primary productivity, and its capacity to structure the space. Finally, some conclusions are presented about the choice criteria of the different approaches in the framne of operational applications. (Author) 20 refs.

  6. Chitin Degradation In Marine Bacteria

    DEFF Research Database (Denmark)

    Paulsen, Sara; Machado, Henrique; Gram, Lone

    2015-01-01

    Introduction: Chitin is the most abundant polymer in the marine environment and the second most abundant in nature. Chitin does not accumulate on the ocean floor, because of microbial breakdown. Chitin degrading bacteria could have potential in the utilization of chitin as a renewable carbon...... and nitrogen source in the fermentation industry.Methods: Here, whole genome sequenced marine bacteria were screened for chitin degradation using phenotypic and in silico analyses.Results: The in silico analyses revealed the presence of three to nine chitinases in each strain, however the number of chitinases...... chitin regulatory system.Conclusions: This study has provided insight into the ecology of chitin degradation in marine bacteria. It also served as a basis for choosing a more efficient chitin degrading production strain e.g. for the use of chitin waste for large-scale fermentations....

  7. Plant biomass degradation by fungi.

    Science.gov (United States)

    Mäkelä, Miia R; Donofrio, Nicole; de Vries, Ronald P

    2014-11-01

    Plant biomass degradation by fungi has implications for several fields of science. The enzyme systems employed by fungi for this are broadly used in various industrial sectors such as food & feed, pulp & paper, detergents, textile, wine, and more recently biofuels and biochemicals. In addition, the topic is highly relevant in the field of plant pathogenic fungi as they degrade plant biomass to either gain access to the plant or as carbon source, resulting in significant crop losses. Finally, fungi are the main degraders of plant biomass in nature and as such have an essential role in the global carbon cycle and ecology in general. In this review we provide a global view on the development of this research topic in saprobic ascomycetes and basidiomycetes and in plant pathogenic fungi and link this to the other papers of this special issue on plant biomass degradation by fungi.

  8. Mathematical modelling of paper degradation in books

    OpenAIRE

    Nimmo, A J

    2015-01-01

    Paper cannot be prevented from degrading and does not necessarily degrade uniformly across its volume. It has been established that as paper degrades, VOCs (Volatile Organic Compounds) are produced. This body of work studies paper degradation with respect to the role VOCs play. The thesis investigates how a VOC a ecting the paper's acidity can in turn a ect the degradation rate and through modelling the VOC concentration pro le, the degradation pro le is found. To create the model from a chem...

  9. Working session 1: Tubing degradation

    Energy Technology Data Exchange (ETDEWEB)

    Kharshafdjian, G. [Atomic Energy of Canada, Mississauga, Ontario (Canada); Turluer, G. [IPSN, Fontenay-aux-Roses (France)

    1997-02-01

    A general introductory overview of the purpose of the group and the general subject area of SG tubing degradation was given by the facilitator. The purpose of the session was described as to {open_quotes}develop conclusions and proposals on regulatory and technical needs required to deal with the issues of SG tubing degradation.{close_quotes} Types, locations and characteristics of tubing degradation in steam generators were briefly reviewed. The well-known synergistic effects of materials, environment, and stress and strain/strain rate, subsequently referred to by the acronym {open_quotes}MESS{close_quotes} by some of the group members, were noted. The element of time (i.e., evolution of these variables with time) was emphasized. It was also suggested that the group might want to consider the related topics of inspection capabilities, operational variables, degradation remedies, and validity of test data, and some background information in these areas was provided. The presentation given by Peter Millet during the Plenary Session was reviewed; Specifically, the chemical aspects and the degradation from the secondary side of the steam generator were noted. The main issues discussed during the October 1995 EPRI meeting on secondary side corrosion were reported, and a listing of the potential SG tube degradations was provided and discussed.

  10. Sonolytic degradation of 2-chlorobiphenyl

    Institute of Scientific and Technical Information of China (English)

    张光明; 华天星; 常爱敏

    2004-01-01

    The sonolytic degradation of 2-chlorobiphenyl was investigated. Mass spectroscopy was used to detect the products of sonolytic degradation of 2-chlorobiphenyl. The results show that the products of sonolytic degradation, such as biphenyl, ethyl benzene, diethylbiphenyl, dibutylbiphenyl, phenol, propylphenol and di-tert-butyl phenol are produced by thermolysis and hydroxyl free radical reactions, in which biphenyl counts for almost 40%(mole fraction) of the mother compound and others are at trace level. Rapid accumulation of chloride ion shows quick dechlorination, and 78% organic chlorine is converted into chloride ion. Free radical scavengers, bicarbonate and carbonate, decrease the reaction rate of sonolytic degradation of 2-chlorobiphenyl significantly, and the pseudo 1st order rate constant of sonolytic degradation of 2-chlorobiphenyl decreases linearly with the natural logarithm of the concentration of the added free radical scavenger, showing that the pyrolysis and hydroxyl free radical reaction are the two major pathways for the sonolytic degradation of 2-chlorobiphenyl, in which the hydroxyl radical concentration is estimated to be 1 × 10 10mol/L.

  11. Numerical Simulation of Transonic Fan Under Circumferential Inlet Distortion Using Harmonic Balance Method%跨声风扇周向畸变流动的谐波平衡法计算

    Institute of Scientific and Technical Information of China (English)

    杜鹏程; 宁方飞

    2012-01-01

    Simulating the unsteady flow of transonic fan under circumferential inlet distortion using conventional dual time stepping method would need multiple blade passages or the whole annulus in order to apply the direct periodic condition.Also,the initial transients of the solution cost most of the computation time to decay until it reaches a periodic steady state.This makes unsteady solutions extremely time consuming and hampers its application in fan blading design process.A fast calculation method is needed to estimate the impact of the circumferential inlet distortion on the fan aerodynamic performance.Therefore,the computation feasibility and the computation speed for the unsteady calculation of the fan under circumferential inlet distortion using harmonic balance method which adopts the phase shift condition were studied.Both the sine wave form and the square wave form inlet total pressure distortion were considered.For the sine wave form inlet distortion,only a small numbers of harmonics were needed to obtain comparable results to the dual time stepping method and a maximum factor of 48 speed-up could be achieved.As for the square wave form inlet distortion,more harmonics should be adopted to get accurate results and only a factor of 7 speed-up was achieved.The results demonstrate that the harmonic balance method can apply to the unsteady calculation of transonic fan under circumferential inlet distortion effectively and reduce the computation time significantly.%研究了采用"相位延迟"边界条件的谐波平衡法用于周向进气畸变计算的可行性及其计算效率,考虑了进气总压畸变形式为正弦波和方波的两种情况。对于正弦波形式的进气总压畸变采用较少阶数的谐波计算就可得到和双时间推进法相近的计算结果,计算速度最大可以提高48倍。对于方波形式的进气畸变,则需要采用更多阶数的谐波计算才能还原得到较准确的非定常流场,计算速度提高了7

  12. 斑点追踪技术评价缺血心肌短轴缩短率和圆周应变%Evaluation of Regional Shortening Fraction and Circumferential Strain in Patients with Myocardial Ischemia by Speckle Tracking Imaging

    Institute of Scientific and Technical Information of China (English)

    何艳; 王东平; 陈金国; 张娜; 杨体霞; 张军; 周利民

    2012-01-01

    目的 运用斑点追踪技术(STI)测量缺血心肌的短轴缩短率和圆周应变值,探讨其在诊断心肌缺血,评价心肌功能中的应用价值.方法 对29例心肌缺血患者(冠状动脉狭窄≥75%)和28例正常对照组(冠状动脉没有狭窄)分别行超声心动图检查,采集并记录左室短轴观(二尖瓣水平)的高帧频动态二维灰阶图像,应用二维应变分析软件进行脱机分析,系统自动将左室短轴分为前间隔、前壁、侧壁、后壁、下壁、后间隔6个节段,并给出应变曲线,分别测量各节段心肌的短轴缩短率和圆周应变值.结果 正常对照组的圆周应变曲线是负向峰值曲线,短轴缩短率曲线是正向峰值曲线,整组曲线排列较整齐;而心肌缺血组的应变曲线形态不规则.心肌缺血组圆周应变和短轴缩短率均低于正常对照组,差异有统计学意义(P<0.05).结论 斑点追踪技术能对心肌的二维应变进行定量分析,为临床诊断心肌缺血,评价心肌功能提供了无创性新方法.%Objective To evaluate the clinical value of speckle tracking imaging in the measurement of regional shortening fraction and circumferential strain in patients with myocardial ischemia. Methods Twenty-nine patients with myocardial ischemia and twenty-eight healthy subjects underwent echocardiography,high frame rate two-dimensional images were recorded from the left ventricular short-axis views at the levels of mitral annulus, regional shortening fraction and circumferential strain were measured in the left ventricular short-axis views using two-dimensional strain software. Results Circumferential strain curve, regional shortening fraction curve in healthy group changed regularly, while in myocardial ischemia patients, the curve changed irregularly. Regional shortening fraction and circumferential strain in myocardial ischemia patients showed significant reduction compared with normal myocardium(P<0.05). Conclusion Speckle

  13. 超声衍射时差法检测汽水管道环焊缝根部腐蚀减薄%Time-of-Flight-Diffraction Testing of Steam and Water Piping Circumferential Weld Roots Local Wall-thinning

    Institute of Scientific and Technical Information of China (English)

    钟志民; 张维; 汪明辉

    2016-01-01

    The field feedbacks show that the industry should pay more attention to secondary loop steam and water piping circumferential weld root flow-accelerated corrosion(FAC)in Nuclear Power Plants from field feedbacks. Without effective inspection and supervision, it will lead to serious consequences such as high energy pipe leakage or rupture. The weld root Ultrasonic Time of Flight Diffraction(TOFD) inspection principle and testing results were discussed in detail. It was shown that TOFD can be applied to inspect local wall-thinning ,caused by flow-accelerated corrosion, at circumferential weld roots of secondary loop steam & water piping in nuclear power plants.%工程经验反馈表明,过往关注较少的核电站二回路汽水管道环焊缝根部由流动加速腐蚀引起的局部减薄现象应引起业界重视,如不进行有效的检测和监督,也会导致高能管道泄漏或破裂.本文重点探讨了核电站二回路汽水管道环焊缝根部局部减薄超声衍射时差法的检测原理、试验情况.结果表明,超声衍射时差法可用于检测流动加速腐蚀引起的汽水管道环焊缝根部局部减薄.

  14. 内置式环形耐压液舱不同周向范围的应力分析%Stress analysis of inner annular pressure tank with different circumferential range

    Institute of Scientific and Technical Information of China (English)

    吴春芳; 吴梵; 刘令

    2016-01-01

    为研究内置式环形耐压液舱在液舱周向范围变化时的力学规律,采用 ANSYS有限元法对单壳体内置式耐压液舱进行了强度计算,对液舱与外界是否连通两种载荷工况下的应力情况进了比较分析。结果表明:在两种载荷工况下,液舱周向范围的变化对液舱应力变化的影响规律相同,但液舱内外相连通时的应力值更高;液舱周向范围280°左右时对结构的变形最为有利。%In order to research the mechanics law of inner annular pressure tank with the change in its circumferential range,a strength compilation method of mono-shell inner pressure tank is carried out based on finite element.The stress situations under two kinds of payloads conditions in the tank are compared and analyzed.The result shows that under the two different conditions,the change of tank circumferential range has the same effect on the change of tank shell stress according to the rule.The stress′value is greater when the liquid is connected to the outside.It is most favorable for the struc-ture′s deformation when the range is about 280°.

  15. Redox regulation of insulin degradation by insulin-degrading enzyme.

    Directory of Open Access Journals (Sweden)

    Crystal M Cordes

    Full Text Available Insulin-degrading enzyme (IDE is a thiol sensitive peptidase that degrades insulin and amyloid β, and has been linked to type 2 diabetes mellitus and Alzheimer's disease. We examined the thiol sensitivity of IDE using S-nitrosoglutathione, reduced glutathione, and oxidized glutathione to distinguish the effects of nitric oxide from that of the redox state. The in vitro activity of IDE was studied using either partially purified cytosolic enzyme from male Sprague-Dawley rats, or purified rat recombinant enzyme. We confirm that nitric oxide inhibits the degrading activity of IDE, and that it affects proteasome activity through this interaction with IDE, but does not affect the proteasome directly. Oxidized glutathione inhibits IDE through glutathionylation, which was reversible by dithiothreitol but not by ascorbic acid. Reduced glutathione had no effect on IDE, but reacted with partially degraded insulin to disrupt its disulfide bonds and accelerate its breakdown to trichloroacetic acid soluble fragments. Our results demonstrate the sensitivity of insulin degradation by IDE to the redox environment and suggest another mechanism by which the cell's oxidation state may contribute to the development of, and the link between, type 2 diabetes and Alzheimer's disease.

  16. Photovoltaic failure and degradation modes: PV failure and degradation modes

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Dirk C. [National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway Golden Colorado 80401 USA; Silverman, Timothy J. [National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway Golden Colorado 80401 USA; Wohlgemuth, John H. [National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway Golden Colorado 80401 USA; Kurtz, Sarah R. [National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway Golden Colorado 80401 USA; VanSant, Kaitlyn T. [Colorado School of Mines, 1500 Illinois Street Golden Colorado 8040 USA

    2017-01-30

    The extensive photovoltaic field reliability literature was analyzed and reviewed. Future work is prioritized based upon information assembled from recent installations, and inconsistencies in degradation mode identification are discussed to help guide future publication on this subject. Reported failure rates of photovoltaic modules fall mostly in the range of other consumer products; however, the long expected useful life of modules may not allow for direct comparison. In general, degradation percentages are reported to decrease appreciably in newer installations that are deployed after the year 2000. However, these trends may be convoluted with varying manufacturing and installation quality world-wide. Modules in hot and humid climates show considerably higher degradation modes than those in desert and moderate climates, which warrants further investigation. Delamination and diode/j-box issues are also more frequent in hot and humid climates than in other climates. The highest concerns of systems installed in the last 10 years appear to be hot spots followed by internal circuitry discoloration. Encapsulant discoloration was the most common degradation mode, particularly in older systems. In newer systems, encapsulant discoloration appears in hotter climates, but to a lesser degree. Thin-film degradation modes are dominated by glass breakage and absorber corrosion, although the breadth of information for thin-film modules is much smaller than for x-Si.

  17. Biodegradability of degradable plastic waste.

    Science.gov (United States)

    Agamuthu, P; Faizura, Putri Nadzrul

    2005-04-01

    Plastic waste constitutes the third largest waste volume in Malaysian municipal solid waste (MSW), next to putrescible waste and paper. The plastic component in MSW from Kuala Lumpur averages 24% (by weight), whereas the national mean is about 15%. The 144 waste dumps in the country receive about 95% of the MSW, including plastic waste. The useful life of the landfills is fast diminishing as the plastic waste stays un-degraded for more than 50 years. In this study the compostability of polyethylene and pro-oxidant additive-based environmentally degradable plastics (EDP) was investigated. Linear low-density polyethylene (LLDPE) samples exposed hydrolytically or oxidatively at 60 degrees C showed that the abiotic degradation path was oxidative rather than hydrolytic. There was a weight loss of 8% and the plastic has been oxidized as shown by the additional carbonyl group exhibited in the Fourier transform infra red (FTIR) Spectrum. Oxidation rate seemed to be influenced by the amount of pro-oxidant additive, the chemical structure and morphology of the plastic samples, and the surface area. Composting studies during a 45-day experiment showed that the percentage elongation (reduction) was 20% for McD samples [high-density polyethylene, (HDPE) with 3% additive] and LL samples (LLDPE with 7% additive) and 18% reduction for totally degradable plastic (TDP) samples (HDPE with 3% additive). Lastly, microbial experiments using Pseudomonas aeroginosa on carbon-free media with degradable plastic samples as the sole carbon source, showed confirmatory results. A positive bacterial growth and a weight loss of 2.2% for degraded polyethylene samples were evident to show that the degradable plastic is biodegradable.

  18. Compendium of photovoltaic degradation rates: Photovoltaic degradation rates

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Dirk C. [National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway Golden CO 80401 USA; Kurtz, Sarah R. [National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway Golden CO 80401 USA; VanSant, Kaitlyn [Colorado School of Mines, 1500 Illinois Street Golden CO 8040 USA; Newmiller, Jeff [DNV GL, 2420 Camino Ramon, Suite 300 San Ramon CA 95483 USA

    2016-02-07

    Published data on photovoltaic (PV) degradation measurements were aggregated and re-examined. The subject has seen an increased interest in recent years resulting in more than 11 000 degradation rates in almost 200 studies from 40 different countries. As studies have grown in number and size, we found an impact from sampling bias attributable to size and accuracy. Because of the correlational nature of this study we examined the data in several ways to minimize this bias. We found median degradation for x-Si technologies in the 0.5-0.6%/year range with the mean in the 0.8-0.9%/year range. Hetero-interface technology (HIT) and microcrystalline silicon (..mu..c-Si) technologies, although not as plentiful, exhibit degradation around 1%/year and resemble thin-film products more closely than x-Si. Several studies showing low degradation for copper indium gallium selenide (CIGS) have emerged. Higher degradation for cadmium telluride (CdTe) has been reported, but these findings could reflect a convolution of less accurate studies and longer stabilization periods for some products. Significant deviations for beginning-of-life measurements with respect to nameplate rating have been documented over the last 35 years. Therefore, degradation rates that use nameplate rating as reference may be significantly impacted. Studies that used nameplate rating as reference but used solar simulators showed less variation than similar studies using outdoor measurements, even when accounting for different climates. This could be associated with confounding effects of measurement uncertainty and soiling that take place outdoors. Hotter climates and mounting configurations that lead to sustained higher temperatures may lead to higher degradation in some, but not all, products. Wear-out non-linearities for the worst performing modules have been documented in a few select studies that took multiple measurements of an ensemble of modules during the lifetime of the system. However, the majority

  19. Hydrocarbon degradation by antarctic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Cavanagh, J.A.E.; Nichols, P.D.; McMeekin, T.A.; Franzmann, P.D. [Univ. of Tasmania (Australia)] [and others

    1996-12-31

    Bacterial cultures obtained from sediment samples collected during a trial oil spill experiment conducted at Airport beach, Eastern Antarctica were selectively enriched for n-alkane-degrading and phenanthrenedegrading bacteria. Samples were collected from a control site and sites treated with different hydrocarbon mixtures - Special Antarctic blend (SAB), BP-Visco and orange roughy oils. One set of replicate sites was also treated with water from Organic Lake which had previously been shown to contain hydrocarbon-degrading bacteria. No viable bacteria were obtained from samples collected from sites treated with orange roughy oil. Extensive degradation of n-alkanes by enrichment cultures obtained from sites treated with SAB and BP-Visco occurred at both 25{degrees}C and 10{degrees}C. Extensive degradation of phenanthrene also occurred in enrichment cultures from these sites grown at 25{degrees}C. Concurrent increases of polar lipid in these cultures were also observed. The presence of 1,4-naphthaquinone and 1-naphthol during the growth of the cultures on phenanthrene is unusual and warrants further investigation of the mechanism of phenanthrene-degradation by these Antarctic bacteria.

  20. Secondary degradation mechanisms - A theoretical approach to remedial actions

    Energy Technology Data Exchange (ETDEWEB)

    Rudling, P. [Advanced Nuclear Technology, Uppsala (Sweden)

    2001-04-01

    A failed BWR fuel rod may degrade either by developing long axial cracks and/or transversal breaks. The tendency of failed BWR rods to degrade depends on the fuel design and reactor operation of the failed rod. The knowledge of the degradation mechanisms may be used to develop secondary degradation resistant fuel and/or to mitigate the degradation tendencies during operation of failed fuel. Literature data from three different categories has been analysed: Open literature data on failed BWR rods that have and have not degraded; Data generated in experimental reactors where primary failures have been simulated either by drilling a hole in the intact cladding before the test or by letting water/steam into the rod from a capsule connected to the otherwise intact rod. In addition data related to hydrogen production in the pellet-cladding gap in a failed rod and the subsequent hydrogen ingress and finally the hydride formation in zirconium alloys; Open literature data out-of-pile material tests to improve the knowledge of the secondary degradation mechanisms. To get an idea of the degradation mechanisms one may first characterise the failed fuel rods in commercial BWRs that form axial splits, transversal breaks and also failed rods that do not degrade at all. Considering axial splits in BWRs, they seem to occur mostly for failed fuel rods with intermediate and high burnups, i.e., in rods with small pellet-cladding gaps, that have been subjected to a power ramp. Such data indicate that the axial crack propagation rate is larger than 0.16 mm/h. It is also clear that the axial cracks formed in commercial reactors show mostly brittle cleavage features at reactor operating temperature even though the hydrogen content in the fuel cladding is low, 150-300 wtppm. Macroscopically the brittle cleavage fractures are characterised by: a fracture surface that is perpendicular to the main tensile stress direction i.e., in the cladding circumferential direction, no or very little clad

  1. Secondary degradation mechanisms - A theoretical approach to remedial actions

    Energy Technology Data Exchange (ETDEWEB)

    Rudling, P. [Advanced Nuclear Technology, Uppsala (Sweden)

    2001-04-01

    A failed BWR fuel rod may degrade either by developing long axial cracks and/or transversal breaks. The tendency of failed BWR rods to degrade depends on the fuel design and reactor operation of the failed rod. The knowledge of the degradation mechanisms may be used to develop secondary degradation resistant fuel and/or to mitigate the degradation tendencies during operation of failed fuel. Literature data from three different categories has been analysed: Open literature data on failed BWR rods that have and have not degraded; Data generated in experimental reactors where primary failures have been simulated either by drilling a hole in the intact cladding before the test or by letting water/steam into the rod from a capsule connected to the otherwise intact rod. In addition data related to hydrogen production in the pellet-cladding gap in a failed rod and the subsequent hydrogen ingress and finally the hydride formation in zirconium alloys; Open literature data out-of-pile material tests to improve the knowledge of the secondary degradation mechanisms. To get an idea of the degradation mechanisms one may first characterise the failed fuel rods in commercial BWRs that form axial splits, transversal breaks and also failed rods that do not degrade at all. Considering axial splits in BWRs, they seem to occur mostly for failed fuel rods with intermediate and high burnups, i.e., in rods with small pellet-cladding gaps, that have been subjected to a power ramp. Such data indicate that the axial crack propagation rate is larger than 0.16 mm/h. It is also clear that the axial cracks formed in commercial reactors show mostly brittle cleavage features at reactor operating temperature even though the hydrogen content in the fuel cladding is low, 150-300 wtppm. Macroscopically the brittle cleavage fractures are characterised by: a fracture surface that is perpendicular to the main tensile stress direction i.e., in the cladding circumferential direction, no or very little clad

  2. Clad Degradation - FEPs Screening Arguments

    Energy Technology Data Exchange (ETDEWEB)

    E. Siegmann

    2004-03-17

    The purpose of this report is to document the screening of the cladding degradation features, events, and processes (FEPs) for commercial spent nuclear fuel (CSNF). This report also addresses the effect of some FEPs on both the cladding and the CSNF, DSNF, and HLW waste forms where it was considered appropriate to address the effects on both materials together. This report summarizes the work of others to screen clad degradation FEPs in a manner consistent with, and used in, the Total System Performance Assessment-License Application (TSPA-LA). This document was prepared according to ''Technical Work Plan for Waste Form Degradation Modeling, Testing, and Analyses in Support of LA'' (BSC 2004a [DIRS 167796]).

  3. Radiation degradation of silk protein

    Energy Technology Data Exchange (ETDEWEB)

    Pewlong, W.; Sudatis, B. [Office of Atomic Energy for Peace, Bangkok (Thailand); Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2000-03-01

    Silk fibroin fiber from the domesticated silkworm Bombyx mori was irradiated using an electron beam accelerator to investigate the application of the radiation degradation technique as a means to solubilize fibroin. The irradiation caused a significant degradation of the fiber. The tensile strength of fibroin fiber irradiated up to 2500 kGy decreased rapidly with increasing dose. The presence of oxygen in the irradiation atmosphere enhanced degradation of the tensile strength. The solubilization of irradiated fibroin fiber was evaluated using the following three kinds of solutions: a calcium chloride solution(CaCl{sub 2}/C{sub 2}H{sub 5}OH/H{sub 2}O=1:2:8 in mole ratio), a hydrochloric acid (0.5 N) and a distilled water. Dissolution of fibroin fiber into these solutions was significantly enhanced by irradiation. Especially, an appreciable amount of water soluble proteins was extracted by a distilled water. (author)

  4. Photocatalytic degradation investigation of dicofol

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Photocatalytic degradation of dicofol was investigated on TiO2 nano particles(TiO2-NPs)under UV light irradiation.It was shown that dicofol could be completely degraded into inorganic chloride ion under the condition of 0.25 mg/mL TiO2-NPs,2 h irradiation of 400 W high pressure mercury lamp with a wavelength of 365 nm and air at a rate of 100 mL/min.The effects of the experimental conditions,including the amount of TiO2-NPs,irradiation time and the intensity of light,were studied.The apparent photodegradation rate constant was 0.167/min under the optimal condition.The photocatalytic degradation mechanism of dicofol was also discussed.

  5. Bacterial degradation of fungicide captan.

    Science.gov (United States)

    Megadi, Veena B; Tallur, Preeti N; Mulla, Sikandar I; Ninnekar, Harichandra Z

    2010-12-22

    The phthalimide fungicide captan has been widely used to control plant pathogenic fungi. A strain of Bacillus circulans utilized the fungicide captan as sole source of carbon and energy. The organism degraded captan by a pathway involving its initial hydrolysis to yield cis-1,2,3,6-tetrahydrophthalimide, a compound without fungicidal activity. The formation of this compound was confirmed by HPLC, IR, NMR, and mass spectral analysis. The results also revealed that cis-1,2,3,6-tetrahydrophthalimide was further degraded to o-phthalic acid by a protocatechuate pathway. These findings indicated that there was a complete mineralization of fungicide captan by B. circulans.

  6. The Science of Battery Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, John P. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Physics; El Gabaly Marquez, Farid [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Physics; McCarty, Kevin [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Physics; Sugar, Joshua Daniel [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Physics; Talin, Alec A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Physics; Fenton, Kyle R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Power Sources Design and Development; Nagasubramanian, Ganesan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Power Sources Design and Development; Harris, Charles Thomas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Nanosystems Synthesis/Analysis; Jungjohann, Katherine Leigh [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Nanosystems Synthesis/Analysis; Hayden, Carl C. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Combustion Chemistry Dept.; Kliewer, Christopher Jesse [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Combustion Chemistry Dept.; Hudak, Nicholas S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Power Sources Research and Development; Leung, Kevin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Nanostructure Physics; McDaniel, Anthony H. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Hydrogen and Combustion Technology; Tenney, Craig M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Chemical and Biological Systems; Zavadil, Kevin R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Materials Lab.

    2015-01-01

    This report documents work that was performed under the Laboratory Directed Research and Development project, Science of Battery Degradation. The focus of this work was on the creation of new experimental and theoretical approaches to understand atomistic mechanisms of degradation in battery electrodes that result in loss of electrical energy storage capacity. Several unique approaches were developed during the course of the project, including the invention of a technique based on ultramicrotoming to cross-section commercial scale battery electrodes, the demonstration of scanning transmission x-ray microscopy (STXM) to probe lithium transport mechanisms within Li-ion battery electrodes, the creation of in-situ liquid cells to observe electrochemical reactions in real-time using both transmission electron microscopy (TEM) and STXM, the creation of an in-situ optical cell utilizing Raman spectroscopy and the application of the cell for analyzing redox flow batteries, the invention of an approach for performing ab initio simulation of electrochemical reactions under potential control and its application for the study of electrolyte degradation, and the development of an electrochemical entropy technique combined with x-ray based structural measurements for understanding origins of battery degradation. These approaches led to a number of scientific discoveries. Using STXM we learned that lithium iron phosphate battery cathodes display unexpected behavior during lithiation wherein lithium transport is controlled by nucleation of a lithiated phase, leading to high heterogeneity in lithium content at each particle and a surprising invariance of local current density with the overall electrode charging current. We discovered using in-situ transmission electron microscopy that there is a size limit to lithiation of silicon anode particles above which particle fracture controls electrode degradation. From electrochemical entropy measurements, we discovered that entropy

  7. Operationalizing measurement of forest degradation

    DEFF Research Database (Denmark)

    Dons, Klaus; Smith-Hall, Carsten; Meilby, Henrik

    2015-01-01

    Quantification of forest degradation in monitoring and reporting as well as in historic baselines is among the most challenging tasks in national REDD+ strategies. However, a recently introduced option is to base monitoring systems on subnational conditions such as prevalent degradation activities...... thresholding was found acceptable at both locations. We used supervised classification and manual digitizing for KBM delineation and found acceptable delineation accuracy at both sites with RMSEs of 25–32% compared to ground measurements. Regression of charcoal production on KBM area delineated from QB...

  8. The Science of Battery Degradation.

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, John P; Fenton, Kyle R [Sandia National Laboratories, Albuquerque, NM; El Gabaly Marquez, Farid; Harris, Charles Thomas [Sandia National Laboratories, Albuquerque, NM; Hayden, Carl C.; Hudak, Nicholas [Sandia National Laboratories, Albuquerque, NM; Jungjohann, Katherine Leigh [Sandia National Laboratories, Albuquerque, NM; Kliewer, Christopher Jesse; Leung, Kevin [Sandia National Laboratories, Albuquerque, NM; McDaniel, Anthony H.; Nagasubramanian, Ganesan [Sandia National Laboratories, Albuquerque, NM; Sugar, Joshua Daniel; Talin, Albert Alec; Tenney, Craig M [Sandia National Laboratories, Albuquerque, NM; Zavadil, Kevin R. [Sandia National Laboratories, Albuquerque, NM

    2015-01-01

    This report documents work that was performed under the Laboratory Directed Research and Development project, Science of Battery Degradation. The focus of this work was on the creation of new experimental and theoretical approaches to understand atomistic mechanisms of degradation in battery electrodes that result in loss of electrical energy storage capacity. Several unique approaches were developed during the course of the project, including the invention of a technique based on ultramicrotoming to cross-section commercial scale battery electrodes, the demonstration of scanning transmission x-ray microscopy (STXM) to probe lithium transport mechanisms within Li-ion battery electrodes, the creation of in-situ liquid cells to observe electrochemical reactions in real-time using both transmission electron microscopy (TEM) and STXM, the creation of an in-situ optical cell utilizing Raman spectroscopy and the application of the cell for analyzing redox flow batteries, the invention of an approach for performing ab initio simulation of electrochemical reactions under potential control and its application for the study of electrolyte degradation, and the development of an electrochemical entropy technique combined with x-ray based structural measurements for understanding origins of battery degradation. These approaches led to a number of scientific discoveries. Using STXM we learned that lithium iron phosphate battery cathodes display unexpected behavior during lithiation wherein lithium transport is controlled by nucleation of a lithiated phase, leading to high heterogeneity in lithium content at each particle and a surprising invariance of local current density with the overall electrode charging current. We discovered using in-situ transmission electron microscopy that there is a size limit to lithiation of silicon anode particles above which particle fracture controls electrode degradation. From electrochemical entropy measurements, we discovered that entropy

  9. Environmental Degradation of Solar Reflectors

    Science.gov (United States)

    Bouquet, F. L.

    1985-01-01

    Report presents results of study of atmospheric degradation of large solar reflectors for power generators. Three general types of reflective surfaces investigated. Report also describes computer buildup and removal (by rain and dew) of contamination from reflectors. Data used to determine effects of soil buildup and best method and frequency of washing at various geographic locations.

  10. Photoelectrocatalytic degradation of Rose Bengal

    Institute of Scientific and Technical Information of China (English)

    LIU Hui-ling; ZHOU Ding; LI Xiang-zhong; YUE Ping-tao

    2003-01-01

    An innovative photoelectrode, TiO2/Ti mesh electrode, was prepared by galvanostaticanodisation. The morphology and the crystalline texture of the TiO2 film on mesh electrode were examined by scanning electronic microscopy and Raman spectroscopy respectively. The examination results indicated that the structure and properties of the film depended on anodisation rate, and the anatase was the dominant component under the controlled experimental conditions. Degradation of Rose Bengal(RB) in photocatalytic(PC) and photoelectrocatalytic(PEC) reaction was investigated, the results demonstrated that electric biasing could improve the efficiency of photocatalytic reaction. The measurement results of TOC in photoelectrocatalytic degradation showed that the mineralisation of RB was complete relatively. The comparison between the degradation efficiency of RB in PEC process and that in aqueous TiO2 dispersion was conducted. The results showed that the apparent first-order rate constant of RB degradation in PEC process was larger than that in aqueous dispersion with 0.1%-0.3% TiO2 powder, but was smaller than that in aqueous dispersion with 1.0% TiO2.

  11. Polymeric Materials - introduction and degradation

    DEFF Research Database (Denmark)

    Kontogeorgis, Georgios

    1999-01-01

    These notes support the polymer part of the courses 91742 and 91762 (Materials and Corrosion/degradation of materials) taught in IFAKthey contain a short introduction on group contribution methods for estimating properties of polymers, polymer thermodynamics, viscoelasticity models as well...

  12. Photothermal degradation studies of encapsulants

    Science.gov (United States)

    Liang, R. H.

    1984-01-01

    The reliability physics program at JPL is outlined. The overall objectives and approaches are given in the program. The objectives, approaches and conclusions are given for two specific parts of the programs. These two parts are mechanistic studies of photothermal degradation and performance characteristics of materials with respect to photothermal stresses.

  13. Plant biomass degradation by fungi

    NARCIS (Netherlands)

    Mäkelä, Miia R; Donofrio, Nicole; de Vries, Ronald P; van den Brink, J.

    2014-01-01

    Plant biomass degradation by fungi has implications for several fields of science. The enzyme systems employed by fungi for this are broadly used in various industrial sectors such as food & feed, pulp & paper, detergents, textile, wine, and more recently biofuels and biochemicals. In addition, the

  14. 袖状蒂岛状环形包皮瓣尿道成形术一期修复会阴型尿道下裂%One-stage urethroplasty with circumferential vascular pedicle preputial island flap for perineal hypospadias

    Institute of Scientific and Technical Information of China (English)

    朱再生; 吴汉; 李瑞阳; 汪定海

    2010-01-01

    Objective To report the treatment of perineal hypospadias with one-stage urethroplaty with circumferential vascular pedicle preputial island flap. Methods A circumferential incision was made proximal to the corona and the urethral plate to correct chordee. A U-shaped skin incision was then made surrounding the meatus, and extended to the dorsal prepuce and parallel to the first incision. The tissue between the prepuce and dartos was dissected on the dorsum of penis to fix the prepuce as a neourethra.After mobilizing the loop shaped skin flap through the button-hole of the pedicle, the internal and external sides of the loop were sutured to construct a new urethra, the catheter was removed 10-14 days (mean,12.8 days ) after operation. Results Since 1997, 22 patients with perineal hypospadias were treated.Primary healing was achieved in 18 cases(81.8% ). Fistula happened in 4 patients. Among them, one case with meatal stenosis was treated with dilatation. Another 3 patients were reoperated. The neourethral flap was 3.50-18.00 cm (mean, 9.43 cm) in length. All patients were followed up for more than 6 months. Good cosmetic appearance was achieved in 72. 7% (16/22) of the patients. Conclusions The circumferential vascular pedicle preputial island flap has advantages of good blood supply and autograft for new meatus, which allows the chordee correction and urethroplaty at one stage. It is a good method for the treatment of perineal hypospadias with severe chordee and penoscrotal transposition.%目的 探讨袖状蒂岛状环形包皮瓣尿道成形术一期修复会阴型尿道下裂的临床效果.方法 距冠状沟0.5 cm处环形切开包皮内板和尿道板,脱套以纠正阴茎下曲.沿尿道板两侧平行切开,近端绕尿道口后会合,呈U形,远端环绕包皮到背侧,使新尿道皮瓣呈环状.解剖供应皮瓣的深层皮下组织与阴茎皮肤,形成血管蒂.经纽扣样孔隙,转移环状皮瓣至腹侧.缝合岛状环形皮瓣的内、外缘,形

  15. Treatment of periodontal disease by double circumferential fibrotomy combined with orthodontic method%二次嵴上纤维环切术结合正畸治疗牙周病的临床观察

    Institute of Scientific and Technical Information of China (English)

    董莹丽; 张月兰; 袁建桥

    2015-01-01

    目的:探讨二次嵴上纤维环切术对牙周病患牙牙周附着的影响。方法:选取4例共22颗前牙患有中度牙周炎的成人患者,一侧患牙施行1次嵴上纤维环切(T1组),另一侧行2次环切(T2组)。排齐整平阶段前后分别拍摄患牙的平行投照 X 线片,测量釉牙骨质界至牙槽嵴顶的距离(CEJ-AC),冠根比和牙根长度。并检测患牙的相关牙周指数。采用配对 t 检验进行统计学分析。结果:T2组 CEJ-AC 和冠根比下降大于 T1组(P <0.01),牙周指数的变化与 T1组相比无统计学差异(P >0.05)。结论:二次牙龈环切能增加患牙的牙周附着及牙槽骨相对高度,合理的正畸压入不会造成牙周炎患牙牙根吸收。%Objective:To explore the effects of double circumferential fibrotomy(CF)in the improvement of periodontal attachment of the teeth with periodontal disease.Methods:22 migrated incisors of 4 adults were randomly assigned to one-time CF group (T1 )and double CF group(T2)by center line.Periapical intraoral radiographic examination was performed using paralleling technique at pre-and post-leveling-alignment stage of the teeth.Root length,crown-root ratio and the distance of CEJ-AC were measured.The periodontal in-dicators were also recorded during the orthodontic treatment.Data were statistically analysed by comparative t-test.Results:CEJ-AC and crown root ratio reduction was greater in T2 group than those in T1 group(P 0.05).Conclusion:Double circumferential fibrotomy can improve periodontal attachment, reasonable orthodontic force does not lead to remarkable root resorption of the periodontitis inflicted teeth.

  16. Basis椎弓根螺钉固定加环形植骨融合治疗腰椎滑脱%Basis pedicle screw fixation and posterior instrumented circumferential fusion for the treatment of lumbar spondylolisthesis

    Institute of Scientific and Technical Information of China (English)

    董福龙; 申才良; 张建湘; 汤健; 杨庆国; 江曙

    2011-01-01

    Objective To summarize curative effects of the decompressive laminectomy by posterior approach, reduc tion of spondylolisthesis fixed with Basis pedicle screw and posterior instrumented circumferential fusion in the treat ment of lumbar spondylolisthesis. Methods Thirty-two patients with lumbar spondylolisthesis treated with posterior instrumented circumferential fusion were studied retrospectively. Results All the patients received follow-up for 4 ~ 25 months. Symptoms were disappeared after operations in all the patients. The postoperative X-ray films showed that 29 patients obtained complete reduction,3 partly reduction. This surgical methods produced satisfactory outcomes with the 100% osseous fusion. All the bone grafts were fusion, without screws loosening or breakage or internal fixation loosing was found. Based on Hou Shu-xun Criteria for therapeutical evalution, the efficacy was as follows: excellent in 23 cases,good in 7,and fair in 2,the rate of excellent and good was 94%. Conclusions Posterior instrumented cir cumferential fusion with Basis pedicle screw is an effective method for treating severe lumbar spondylolisthesis.%目的 探讨后路腰椎管减压、Basis椎弓根螺钉系统复位固定加环形植骨融合治疗腰椎滑脱症的疗效.方法 对32例腰椎滑脱症患者行后路腰椎管减压Basis椎弓根螺钉复位固定加环形植骨融合术.结果 32例均获随访,时间4~25个月.患者术后症状均消失,X线片示29例滑脱完全复位,3例部分复位.所有患者均达骨性融合,无椎弓根钉松动、断裂及再滑脱现象.根据侯树勋等疗效评定标准评定:优23例,良7例,可2例,优良率94%.结论 Basis椎弓根固定系统复位固定加环形植骨融合治疗腰椎滑脱症临床疗效满意,可作为治疗严重腰椎滑脱的首选方法.

  17. Microstructural degradation in compound tubes

    Energy Technology Data Exchange (ETDEWEB)

    Salonen, J.; Auerkari, P. [VTT Manufacturing Technology, Espoo (Finland)

    1996-12-31

    In order to quantify microstructural degradation at high temperatures, samples of SA 210 / AISI 304 L compound tube material were annealed in the temperature range 540-720 deg C for 1 to 1 000 hours. The hardness of the annealed material was measured and the micro structure of the samples was investigated with optical and scanning electron microscopy. Microstructural degradation was characterised by the carbide structure in the ferritic-pearlitic base material and by the depth of decarburised and carburised zones of the compound tube interface. The observed changes were quantified in terms of their time and temperature dependence and diffusion coefficients of the process. The results can be used in estimating the extent of thermal exposure of high-temperature components after long-term service or after incidences of overheating. (orig.) (4 refs.)

  18. Radiation degradation of silk protein

    Energy Technology Data Exchange (ETDEWEB)

    Wachiraporn Pewlong; Boonya Sudatis [Office of Atomic Energy for Peace, Bangkok (Thailand); Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2000-09-01

    Silk fibroin fiber from the domesticated silkworm Bombyx mori was irradiated in the dose range up to 2500 kGy using an electron beam accelerator to apply the radiation degradation technique as a means to solubilize fibroin. The tensile strength of irradiated fibroin fiber decreased with increasing dose and the presence of oxygen in the irradiation atmosphere enhanced the degradation. The solubilization of irradiated fibroin fiber was evaluated using the following three kinds of solutions: calcium chloride solution (CaCl{sub 2}/C{sub 2}H{sub 5}OH/H{sub 2}O = 1 : 2 : 8 in mole ratio), hydrochloric acid (0.5N) and distilled water. Dissolution of fibroin fiber into these solutions was significantly enhanced by irradiation. Especially, an appreciable amount of water-soluble protein was extracted by distilled water. (author)

  19. Learner intuitions about energy degradation

    CERN Document Server

    Daane, Abigail R; Vokos, Stamatis

    2013-01-01

    A primary learning goal for energy in K-12 science instruction is that energy cannot be created or destroyed. However, learners' everyday ideas about energy often involve energy being "used up" or "wasted." In physics, the concept of energy degradation can connect those everyday ideas to the principle of energy conservation. Learners' spontaneous discussions of aspects of energy degradation and the second law of thermodynamics include ideas concerning the inaccessibility, usefulness and dispersion of energy. These ideas have motivated us to introduce new learning goals into our K-12 teacher professional development courses. We identify alignments between these learning goals and learners' informal ideas and discuss instructional implications created by these alignments. Our aim is to create stronger ties between formal physics knowledge and sociopolitical issues by making these learning goals a priority in our professional development.

  20. PEM Degradation Investigation Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Dan Stevenson; Lee H Spangler

    2010-10-18

    This project conducted fundamental studies of PEM MEA degradation. Insights gained from these studies were disseminated to assist MEA manufacturers in understanding degradation mechanisms and work towards DOE 2010 fuel cell durability targets.

  1. Numerical Simulation Study of Natural Convection Heat Transfer Performance of Circumferential Finned Tube%环形翅片管自然对流传热特性的数值模拟研究

    Institute of Scientific and Technical Information of China (English)

    李家乐

    2013-01-01

    利用FLUENT数值模拟方法,研究了自然对流条件下环形翅片管几何参数对其对流换热性能的影响.结果表明:随翅片间距的增大,单位长度散热量先增大后减小,表面平均自然对流换热系数及单位面积散热量先增大后基本稳定不变;翅片厚度对换热性能的影响随间距变化而变化.通过模拟计算,为自然对流条件下翅片管的优化设计提供了参考.%Applying numerical simulation, the paper studies the effect of fin spacing and fin thickness of circumferential finned tube on natural convection heat transfer performance. The results indicate that, with the increase of fin spacing, unit length heat dissipating capacity increases at the previous period and decreases at the later period. The average surface convection coefficient of heat transfer and unit surface area heat dissipating capacity increase at first and then keep constant. The effect of fin thickness on heat transfer performance changes along with the fin spacing. By simulation, it provides reference to the optimization design of finned tube.

  2. Meta-analysis of lumbar posterolateral fusion versus circumferential fusion in the treatment of the lumbar disease%腰椎后外侧融合与360°融合的系统评价

    Institute of Scientific and Technical Information of China (English)

    崔璀; 朱悦; 韩秀鑫

    2009-01-01

    目的 对腰椎后外侧融合与360°融合治疗腰椎疾病的疗效进行系统对比评价.方法 计算机检索MEDLINE(1966.1-2007.12,Ovid检索平台)、EMBASE(1984.1-2007.12)、Cochrance Central Register of Controlled Trial(4th Quarter 2007)、中国生物医学文献数据库(1986.1-2007.12)等,手工检索Spine、European SPine Jurnal、The Journat of Bone and Joint Surgery、、、等相关期刊,检索两种融合术式的相关病例研究结果、综述等相关内容,并评价纳入研究的方法学质量,采用RevMan 5.0,5.0软件对总体疗效、融合率、二次手术率、并发症发生率、平均手术时间、手术出血量进行荟萃分析.结果 有4个临床随机对照试验(RCT)符合纳入标准,共437例患者.在融合率[OR 0.47,95%CI(0.24,0.94)]、并发症发生率[OR 0.53,95%CI(0.32,0.87)]、术中出血量[加权均数差值(WMD)=-349.95,95%CI(-561.64,-138.26)]方面,360°融合组要高于后外侧融合组,差异具有统计学意义(P=0.030、0.010、0.001);在二次手术率[OR 2.28,95%CI(1.30,3.98)]方面,后外侧融合组要高于360°融合组,差异具有统计学意义(P=0.004);在总体疗效[OR 1.04,95%CI(0.64,1.68)]和手术时间[WMD=-90.24,95%CI(-190.20,9.71)]上,两组差异无统计学意义(P=0.870、0.080).结论 360°融合组相比于后外侧融合组,能显著提高融合率,降低二次手术率,但并发症、术中出血量也显著高于后者.本研究结果尚需要多中心大样本RCT进一步证实.%Objective To evaluate the efficacy of lumbar posterolateral fusion versus circumferential fusion in the treatment of the lumbar disease. Methods Searched MEDLINE(January, 1966 to December, 2007), EMBASE (January, 1984 to December, 2007), Coehrance Central Register of Controlled Trial (4th Quarter 2007), The China Biological Medicine Database (1984 to December, 2007), and hand searched several related journals, such as Spine, European Spine Journal, The Journal of Bone and Joint Surgery, Chinese

  3. Regeneración ósea de un defecto circunferencial de tres paredes con hueso autólogo Autologous bone regeneration of an circumferential three walls defect

    Directory of Open Access Journals (Sweden)

    N. Escudero Castaño

    2008-08-01

    Full Text Available La periodontitis provoca, a lo largo de su proceso evolutivo, un deterioro de los tejidos periodontales, entreellos del hueso alveolar. En la mayoría de las ocasiones, la progresión de esta enfermedad puede ocasionar defectos óseos. Su tratamiento consistirá en la eliminación de los factores etiológicos y recuperar, en la medida de loposible, la estructura perdida mediante diferentes técnicas regenerativas o resectivas. En el presente artículo, se muestra una opción para el tratamiento de un defecto óseo circunferencial de tres paredes, comparándolo condiferentes alternativas de tratamiento para combatir este defecto.The periodontal disease causes, along the evolutive process of the illness, a damage of periodontal tissues,including the alveolar bone; in many times, the evolution of the pathology makes irregular bone deformities. The treatment of that disease could be to eliminate the etiological factors and to recuperate as much as possible, the missed structure with regenerative and resectives techniques. In this article, we will set up a clinical case where we will describe a treatment option of a circumferential bone defect and we will compare that treatment with others alternatives.

  4. Flow accelerated organic coating degradation

    Science.gov (United States)

    Zhou, Qixin

    Applying organic coatings is a common and the most cost effective way to protect metallic objects and structures from corrosion. Water entry into coating-metal interface is usually the main cause for the deterioration of organic coatings, which leads to coating delamination and underfilm corrosion. Recently, flowing fluids over sample surface have received attention due to their capability to accelerate material degradation. A plethora of works has focused on the flow induced metal corrosion, while few studies have investigated the flow accelerated organic coating degradation. Flowing fluids above coating surface affect corrosion by enhancing the water transport and abrading the surface due to fluid shear. Hence, it is of great importance to understand the influence of flowing fluids on the degradation of corrosion protective organic coatings. In this study, a pigmented marine coating and several clear coatings were exposed to the laminar flow and stationary immersion. The laminar flow was pressure driven and confined in a flow channel. A 3.5 wt% sodium chloride solution and pure water was employed as the working fluid with a variety of flow rates. The corrosion protective properties of organic coatings were monitored inline by Electrochemical Impedance Spectroscopy (EIS) measurement. Equivalent circuit models were employed to interpret the EIS spectra. The time evolution of coating resistance and capacitance obtained from the model was studied to demonstrate the coating degradation. Thickness, gloss, and other topography characterizations were conducted to facilitate the assessment of the corrosion. The working fluids were characterized by Fourier Transform Infrared Spectrometer (FTIR) and conductivity measurement. The influence of flow rate, fluid shear, fluid composition, and other effects in the coating degradation were investigated. We conclude that flowing fluid on the coating surface accelerates the transport of water, oxygen, and ions into the coating, as

  5. Applications and extensions of degradation modeling

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, F.; Subudhi, M.; Samanta, P.K. (Brookhaven National Lab., Upton, NY (United States)); Vesely, W.E. (Science Applications International Corp., Columbus, OH (United States))

    1991-01-01

    Component degradation modeling being developed to understand the aging process can have many applications with potential advantages. Previous work has focused on developing the basic concepts and mathematical development of a simple degradation model. Using this simple model, times of degradations and failures occurrences were analyzed for standby components to detect indications of aging and to infer the effectiveness of maintenance in preventing age-related degradations from transforming to failures. Degradation modeling approaches can have broader applications in aging studies and in this paper, we discuss some of the extensions and applications of degradation modeling. The application and extension of degradation modeling approaches, presented in this paper, cover two aspects: (1) application to a continuously operating component, and (2) extension of the approach to analyze degradation-failure rate relationship. The application of the modeling approach to a continuously operating component (namely, air compressors) shows the usefulness of this approach in studying aging effects and the role of maintenance in this type component. In this case, aging effects in air compressors are demonstrated by the increase in both the degradation and failure rate and the faster increase in the failure rate compared to the degradation rate shows the ineffectiveness of the existing maintenance practices. Degradation-failure rate relationship was analyzed using data from residual heat removal system pumps. A simple linear model with a time-lag between these two parameters was studied. The application in this case showed a time-lag of 2 years for degradations to affect failure occurrences. 2 refs.

  6. Applications and extensions of degradation modeling

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, F.; Subudhi, M.; Samanta, P.K. [Brookhaven National Lab., Upton, NY (United States); Vesely, W.E. [Science Applications International Corp., Columbus, OH (United States)

    1991-12-31

    Component degradation modeling being developed to understand the aging process can have many applications with potential advantages. Previous work has focused on developing the basic concepts and mathematical development of a simple degradation model. Using this simple model, times of degradations and failures occurrences were analyzed for standby components to detect indications of aging and to infer the effectiveness of maintenance in preventing age-related degradations from transforming to failures. Degradation modeling approaches can have broader applications in aging studies and in this paper, we discuss some of the extensions and applications of degradation modeling. The application and extension of degradation modeling approaches, presented in this paper, cover two aspects: (1) application to a continuously operating component, and (2) extension of the approach to analyze degradation-failure rate relationship. The application of the modeling approach to a continuously operating component (namely, air compressors) shows the usefulness of this approach in studying aging effects and the role of maintenance in this type component. In this case, aging effects in air compressors are demonstrated by the increase in both the degradation and failure rate and the faster increase in the failure rate compared to the degradation rate shows the ineffectiveness of the existing maintenance practices. Degradation-failure rate relationship was analyzed using data from residual heat removal system pumps. A simple linear model with a time-lag between these two parameters was studied. The application in this case showed a time-lag of 2 years for degradations to affect failure occurrences. 2 refs.

  7. Nylon biodegradation by lignin-degrading fungi.

    OpenAIRE

    Deguchi, T; Kakezawa, M; Nishida, T

    1997-01-01

    The biodegradation of nylon by lignin-degrading fungi was investigated. The fungus IZU-154 significantly degraded nylon-66 membrane under ligninolytic conditions. Nuclear magnetic resonance analysis showed that four end groups, CHO, NHCHO, CH3, and CONH2, were formed in the biodegraded nylon-66 membranes, suggesting that nylon-66 was degraded oxidatively.

  8. Degradation analysis of thin film photovoltaic modules

    Energy Technology Data Exchange (ETDEWEB)

    Radue, C., E-mail: chantelle.radue@nmmu.ac.z [Department of Physics, PO Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Dyk, E.E. van [Department of Physics, PO Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa)

    2009-12-01

    Five thin film photovoltaic modules were deployed outdoors under open circuit conditions after a thorough indoor evaluation. Two technology types were investigated: amorphous silicon (a-Si:H) and copper indium gallium diselenide (CIGS). Two 14 W a-Si:H modules, labelled Si-1 and Si-2, were investigated. Both exhibited degradation, initially due to the well-known light-induced degradation described by Staebler and Wronski [Applied Physics Letters 31 (4) (1977) 292], and thereafter due to other degradation modes such as cell degradation. The various degradation modes contributing to the degradation of the a-Si:H modules will be discussed. The initial maximum power output (P{sub MAX}) of Si-1 was 9.92 W, with the initial light-induced degradation for Si-1 approx30% and a total degradation of approx42%. For Si-2 the initial P{sub MAX} was 7.93 W, with initial light-induced degradation of approx10% and a total degradation of approx17%. Three CIGS modules were investigated: two 20 W modules labelled CIGS-1 and CIGS-2, and a 40 W module labelled CIGS-3. CIGS-2 exhibited stable performance while CIGS-1 and CIGS-3 exhibited degradation. CIGS is known to be stable over long periods of time, and thus the possible reasons for the degradation of the two modules are discussed.

  9. Serological studies on chloridazon-degrading bacteria.

    Science.gov (United States)

    Layh, G; Böhm, R; Eberspächer, J; Lingens, F

    1983-01-01

    Agglutination tests and immunofluorescence tests with antisera against four strains of chloridazon-degrading bacteria revealed the serological uniformity of a group of 22 chloridazon-degrading bacterial strains. No serological relationship could be found between chloridazon-degrading bacteria and representatives of other Gram-negative bacteria. This was demonstrated by agglutination tests, including testing of the antiserum against Acinetobacter calcoaceticus, and by immunofluorescence tests, including testing of the sera against Pseudomonas and Acinetobacter strains. The tests were performed with 31 representatives of different Gram-negative bacteria, and with 22 strains of chloridazon-degrading bacteria as antigens. Differences in the extent of agglutination reactions and antibody titres among chloridazon-degrading bacterial strains together with cross-adsorption xperiments, suggest a rough classification of chloridazon-degrading bacteria into two subgroups. On the basis of immunofluorescence data, a linkage-map was worked out to represent serological relationships in the group of chloridazon-degrading strains.

  10. Protease-degradable electrospun fibrous hydrogels

    Science.gov (United States)

    Wade, Ryan J.; Bassin, Ethan J.; Rodell, Christopher B.; Burdick, Jason A.

    2015-03-01

    Electrospun nanofibres are promising in biomedical applications to replicate features of the natural extracellular matrix (ECM). However, nearly all electrospun scaffolds are either non-degradable or degrade hydrolytically, whereas natural ECM degrades proteolytically, often through matrix metalloproteinases. Here we synthesize reactive macromers that contain protease-cleavable and fluorescent peptides and are able to form both isotropic hydrogels and electrospun fibrous hydrogels through a photoinitiated polymerization. These biomimetic scaffolds are susceptible to protease-mediated cleavage in vitro in a protease dose-dependent manner and in vivo in a subcutaneous mouse model using transdermal fluorescent imaging to monitor degradation. Importantly, materials containing an alternate and non-protease-cleavable peptide sequence are stable in both in vitro and in vivo settings. To illustrate the specificity in degradation, scaffolds with mixed fibre populations support selective fibre degradation based on individual fibre degradability. Overall, this represents a novel biomimetic approach to generate protease-sensitive fibrous scaffolds for biomedical applications.

  11. STRUCTURAL PERFORMANCE OF DEGRADED REINFORCED CONCRETE MEMBERS.

    Energy Technology Data Exchange (ETDEWEB)

    Braverman, J.I.; Miller, C.A.; Ellingwood, B.R.; Naus, D.J.; Hofmayer, C.H.; Bezler, P.; Chang, T.Y.

    2001-03-22

    This paper describes the results of a study to evaluate, in probabilistic terms, the effects of age-related degradation on the structural performance of reinforced concrete members at nuclear power plants. The paper focuses on degradation of reinforced concrete flexural members and shear walls due to the loss of steel reinforcing area and loss of concrete area (cracking/spalling). Loss of steel area is typically caused by corrosion while cracking and spalling can be caused by corrosion of reinforcing steel, freeze-thaw, or aggressive chemical attack. Structural performance in the presence of uncertainties is depicted by a fragility (or conditional probability of failure). The effects of degradation on the fragility of reinforced concrete members are calculated to assess the potential significance of various levels of degradation. The fragility modeling procedures applied to degraded concrete members can be used to assess the effects of degradation on plant risk and can lead to the development of probability-based degradation acceptance limits.

  12. Single gene retrieval from thermally degraded DNA

    Indian Academy of Sciences (India)

    Lianwen Zhang; Lianwen Zhang

    2005-12-01

    To simulate single gene retrieval from ancient DNA, several related factors have been investigated. By monitoring a 889 bp polymerase chain reaction (PCR) product and genomic DNA degradation, we find that heat and oxygen (especially heat) are both crucial factors influencing DNA degradation. The heat influence, mainly represented by temperature and heating time, affects the DNA degradation via DNA depurination followed by cleavage of nearby phosphodiesters. The heating time influence is temperature-dependent. By reactive oxygen species (ROS) scavenging and 1,3-diphenyl-isobenzofuran (DPBF) bleaching experiments the influence of oxygen on DNA thermal degradation was shown to occur via a singlet oxygen pathway. A comparative study of the thermal degradation of cellular DNA and isolated DNA showed that cellular lipids can aggravate DNA thermal degradation. These results confirm the possibility of gene amplification from thermally degraded DNA. They can be used to evaluate the feasibility of the retrieval of single gene from ancient remains.

  13. Starch-degrading polysaccharide monooxygenases.

    Science.gov (United States)

    Vu, Van V; Marletta, Michael A

    2016-07-01

    Polysaccharide degradation by hydrolytic enzymes glycoside hydrolases (GHs) is well known. More recently, polysaccharide monooxygenases (PMOs, also known as lytic PMOs or LPMOs) were found to oxidatively degrade various polysaccharides via a copper-dependent hydroxylation. PMOs were previously thought to be either GHs or carbohydrate binding modules (CBMs), and have been re-classified in carbohydrate active enzymes (CAZY) database as auxiliary activity (AA) families. These enzymes include cellulose-active fungal PMOs (AA9, formerly GH61), chitin- and cellulose-active bacterial PMOs (AA10, formerly CBM33), and chitin-active fungal PMOs (AA11). These PMOs significantly boost the activity of GHs under industrially relevant conditions, and thus have great potential in the biomass-based biofuel industry. PMOs that act on starch are the latest PMOs discovered (AA13), which has expanded our perspectives in PMOs studies and starch degradation. Starch-active PMOs have many common structural features and biochemical properties of the PMO superfamily, yet differ from other PMO families in several important aspects. These differences likely correlate, at least in part, to the differences in primary and higher order structures of starch and cellulose, and chitin. In this review we will discuss the discovery, structural features, biochemical and biophysical properties, and possible biological functions of starch-active PMOs, as well as their potential application in the biofuel, food, and other starch-based industries. Important questions regarding various aspects of starch-active PMOs and possible economical driving force for their future studies will also be highlighted.

  14. Degradation of Acenaphthene by Ozone

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Objective To investigate the oxidation of acenaphthene (Ace), a polycyclic aromatic hydrocarbon (PAH) with a saturated C-C bond by ozone and to characterize the intermediate products of ozonation. Methods Ozone was generated from filtered dry oxygen by an ozone generator and continually bubbled into a reactor containing 1g/L Ace dissolved in an acetonitrile/water solvent mixture (90/10, v/v) at a rate of 0.5 mg/s. HPLC was used to analyze the Ace concentration. Total organic carbon (TOC) was used to measure the amount of water soluble organic compounds. GC-MS was used to identify the ozonized products. Oxygen uptake rate (OUR) of activated sludge was used to characterize the biodegradability of ozonized products. Results During the ozonation process, Ace was degraded, new organic compounds were produced and these intermediate products were difficult mineralize by ozone, with increasing TOC of soluble organics. The ozonized products were degraded by activated sludge more easily than Ace. Conclusion Ozonation decomposes the Ace and improves its biodegradability. The ozonation combined with biological treatment is probably an efficient and economical way to mineralize acenaphthene in wastewater.

  15. Environmental Degradation: Causes and Consequences

    Directory of Open Access Journals (Sweden)

    Swati Tyagi

    2014-08-01

    Full Text Available The subject of environmental economics is at the forefront of the green debate: the environment can no longer be viewed as an entity separate from the economy. Environmental degradation is of many types and have many consequences. To address this challenge a number of studies have been conducted in both developing and developed countries applying different methods to capture health benefits from improved environmental quality. Minimizing exposure to environmental risk factors by enhancing air quality and access to improved sources of drinking and bathing water, sanitation and clean energy is found to be associated with significant health benefits and can contribute significantly to the achievement of the Millennium Development Goals of environmental sustainability, health and development. In this paper, I describe the national and global causes and consequences of environmental degradation and social injustice. This paper provides a review of the literature on studies associated with reduced environmental risk and in particular focusing on reduced air pollution, enhanced water quality and climate change mitigation.

  16. Early detection of materials degradation

    Science.gov (United States)

    Meyendorf, Norbert

    2017-02-01

    Lightweight components for transportation and aerospace applications are designed for an estimated lifecycle, taking expected mechanical and environmental loads into account. The main reason for catastrophic failure of components within the expected lifecycle are material inhomogeneities, like pores and inclusions as origin for fatigue cracks, that have not been detected by NDE. However, material degradation by designed or unexpected loading conditions or environmental impacts can accelerate the crack initiation or growth. Conventional NDE methods are usually able to detect cracks that are formed at the end of the degradation process, but methods for early detection of fatigue, creep, and corrosion are still a matter of research. For conventional materials ultrasonic, electromagnetic, or thermographic methods have been demonstrated as promising. Other approaches are focused to surface damage by using optical methods or characterization of the residual surface stresses that can significantly affect the creation of fatigue cracks. For conventional metallic materials, material models for nucleation and propagation of damage have been successfully applied for several years. Material microstructure/property relations are well established and the effect of loading conditions on the component life can be simulated. For advanced materials, for example carbon matrix composites or ceramic matrix composites, the processes of nucleation and propagation of damage is still not fully understood. For these materials NDE methods can not only be used for the periodic inspections, but can significantly contribute to the material scientific knowledge to understand and model the behavior of composite materials.

  17. 周向重叠三分螺旋折流板换热器性能比较%Performance comparison of circumferential overlap trisection helical baffle heat exchanger

    Institute of Scientific and Technical Information of China (English)

    董聪; 陈亚平; 吴嘉峰; 操瑞兵

    2013-01-01

    Numerical simulation of flow and heat transfer performances were conducted in respect for four helical baffle heat exchangers with identical equilateral triangle tube layout and approximate spiral pitch but different baffle shapes and assembly configurations,i.e.,a trisection circumferential overlap baffle scheme with the baffle incline angle of 20° (20°TCO),a quadrant circumferential overlap baffle scheme with the baffle incline angle of 18° (18°QCO),a quadrant end-to-end baffle scheme with the baffle incline angle of 18° (18°QEE),and a continuous helical baffle scheme with the baffle helix angle of 18.4° (18.4°CH).The velocity-vector superimposed pressure or velocity nephograms meridian slices and the unfolded concentric hexagonal slices and the curves of local average heat fluxes on nine heat transfer tubes within a 60° sector region and on the four concentric heat transfer tube layers were presented.The results show that each baffle chamber contains secondary flow and there exists reverse leakage at the V-notch region,but the leakage of 20°TCO scheme is the least of the four schemes.Among the four schemes,the 20°TCO scheme has the highest shell-side heat transfer factor jo,friction coefficient fo and average comprehensive index (jo/fo) ; the 18°QCO scheme has the second highest values of both shell-side heat transfer factor joand friction coefficient fo; although,the 18.4°CH scheme has the lowest shell-side friction coefficient fo,its shell-side heat transfer factor jo and average comprehensive index (jo/fo) are the lowest.%对采用正三角形布管且螺距相同的4种螺旋折流板换热器方案,即倾斜角为20°三分周向重叠(20°TCO)、倾斜角为18°四分周向重叠(18°QCO)、倾斜角为18°首尾相连(18°QEE)以及螺旋角为18.4°的连续(18.4°CH)螺旋折流板换热器的流动和传热性能进行数值模拟.给出了子午切面、同心正六边形切面上速度矢量叠加压力或速度云图分布以及60

  18. 颈动脉圆周应变在心血管危险分层中的临床应用价值%Clinical application value of carotid circumferential strain in cardiovascular risk stratification

    Institute of Scientific and Technical Information of China (English)

    黄锡藩; 谭志伟; 刘彩娟; 梁可建; 严家兴

    2015-01-01

    目的:采用超声二维斑点追踪手段对不存在颈动脉粥样硬化斑块的患者进行颈动脉整体圆周应变检测,分析其颈动脉弹性,评价颈动脉圆周应变应用于心血管危险分层工作中的作用。方法:选取88例心内科住院患者,按照 Framingham 危险评分(FRS)将其划分为低危组、中危组以及高危组。对所有患者的颈总动脉收缩期峰值 CS 以及颈动脉内中膜厚度 IMT 进行测量,针对 CS 给予脉压差校正处理(CS/ PP),分析 CS、CS/ PP 以及 IMT 之间的关系。结果:CS、CS/ PP 以及 IMT 三者在低危组和中危组患者中的比较差异明显,在低危组以及高危组间比较差异显著,具有统计学意义( P ﹤0.05);CS/ PP 在三组患者间比较差异明显,具有统计学意义(P ﹤0.05)。结论:采用超声二维斑点追踪技术能够实现对颈动脉弹性情况的有效反映,利用 IMT 以及CS 能够针对患者颈动脉硬化进行结构评价以及功能评估,预测冠状动脉具体病变情况。%Objective Carotid global circumferential strain detection was conducted on the patients without carotid atherosclerotic plaque by using two - dimensional ultrasound speckle tracking methods to analyze the carotid elasticity and evaluate roles of the carotid circumferen-tial strain in the cardiovascular risk stratification. Method Eighty eight cases of the hospitalized patients in the department of cardiology of our hospital were randomly selected. According to the Framingham risk score(FRS),they were divided into low risk group,medium risk group and high risk group. Carotidartery peak systolic(CS)and intima - media thickness(IMT)of all the patients were measured. Based on CS,correc-tion and treatment of pulse pressure difference was given to analyze the relationship between CS,CS/ PP and IMT. Results There were obvious differences of CS,CS/ PP and IMT between the low risk group and the medium risk group

  19. Research on Ultrasonic Flexible Phased Array Technology for Circumferential Testing of Ultra-high Pressure Crystal Kettle%超高压水晶釜周向检测超声柔性相控阵技术研究

    Institute of Scientific and Technical Information of China (English)

    钟海见; 郭伟灿; 凌张伟

    2016-01-01

    针对内外径之比通常小于0.6的超高压水晶釜超声检测技术,常规的周向超声检测技术存在灵敏度低、缺陷定位困难等技术难点,同时国内外还没有相应的检测标准和成熟的检测工艺。相对于常规超声技术,相控阵技术可以在不更换探头的情况下,实现整个检测区域多角度、多方向扫查和动态聚焦检测,并结合实时成像技术,直观地显示缺陷的位置、分布、尺寸等信息。在试验研究的基础上,提出超高压水晶釜周向超声柔性相控阵检测技术,提出的柔性探头可以良好匹配超高压水晶釜圆柱表面,根据曲面形状设计聚焦法则,可以有效解决超高压水晶釜周向超声检测的技术难题。试验结果表明,柔性相控阵技术对超高压水晶釜的表面和内部缺陷均具有较高的检测精度和可靠性。%For the ultra-high pressure crystal kettle with the ratio of inner radius to outer radius less than 0.6,the conventional circumferential ultrasonic testing could not receive satisfied performance,because of the low sensitivity,locating defects difficultly.Comparing to conventional ultrasonic testing,ultrasonic phased array technology could realized the multi-angle,multi-direction scanning and dynamic focusing de-tection in the entire detecting region without replacement of probe and can visually display the location, distribution,size of defects utilizing the real time imaging technology.Based on the experimental study,the circumferential ultrasonic phased array technique is proposed for ultra-high pressure crystal kettle.A flexi-ble probe is designed which can be good match to the surface of ultra-high pressure crystal kettle.The fo-cal law is designed based on the curved shape and can effective excite the probe.The experimental result show that the flexible phased array technology proposed in this paper has high detection precision and re-liability for the detection of

  20. 周向长弧形弹簧双质量飞轮静刚度理论模型研究%Study on Static Stiffness Model of Long Circumferential Spring Dual Mass Flywheel

    Institute of Scientific and Technical Information of China (English)

    胡伟; 江征风; 曾荣; 陈雷; 王立伟

    2014-01-01

    The static stiffness model of circumferential arc spring dual mass flywheel (DMF-CS) was established based on the feature of changeable helix angle of arc spring.Based on the theoretical equations of the spring curve,according to periodical changing characteristics of the helix angle,the relation between transferred torque and total deformation of the arc spring was figured out using relat-ed mechanics theory.Applying the static stiffness test bench of DMF-CS,the experimental study was carried out.The theoretical and experimental results were compared,which validated the feasibility and accuracy of the established model.Meanwhile,the established model was compared with other theoretical models,which show that this model improves the precision of the static stiffness calcula-tion.%以弧形弹簧自身变螺旋角的特征为基础建立了周向长弧形弹簧双质量飞轮静刚度理论模型。基于弧形弹簧曲线方程,根据弧形弹簧螺旋角成周期变化的特点,结合相关力学理论推导出弧形弹簧传递扭矩与总变形之间的关系(弹簧静刚度)。应用周向长弧形弹簧双质量飞轮静刚度实验台进行了试验研究,试验结果与理论结果的对比验证了该静刚度理论模型的可行性与准确性;对比多种其他静刚度理论模型,该方法提高了静刚度计算精度。

  1. Ametryne degradation by ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Debora Cristina de; Mori, Manoel Nunes; Duarte, Celina Lopes [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mails: deboracandrade@globo.com; mnmori@ipen.br; clduarte@ipen.br; Melo, Rita Paiva [Technological and Nuclear Institute (ITN), Sacavem (Portugal)]. E-mail: ritamelo@itn.pt

    2007-07-01

    Ametryne may be released to the environment during its manufacture, transport, storage, formulation and use as selective herbicide for the control of annual broadleaf and grass weeds. It is applied as an aqueous suspension for preemergence or post-directed applications on crops. Depending on the pesticide formulation and type of application, ametryne residues may be detectable in water, soil and on the surfaces for months or years. The herbicide used to this study was Ametryne (commercial name, Gesapax 500), commonly used on field crops and on corn and commercialized since 1975. Ametryne was analyzed by gas chromatography (GC Shimadzu 17A), after extraction with hexane/dichloromethane (1:1 v/v) solution. The calibration curve was obtained with a regression coefficient of 0.9871. In addition, the relative standard deviation was lower than 10%. The radiation-processing yield was evaluated by the destruction G-value (Gd) (Eq. 1), that is defined by the number of destroyed molecules by absorption of 100 eV of energy from ionizing radiation. Different concentrations of the herbicide (11.4 mol L{sup -1}; 22.7 mol L{sup -1}; 34.1 mol L{sup -1} and 45.5 mol L{sup -1}) were irradiated at the AECL 'Gammacell 220' {sup 60}Co source, with 1 kGy, 3 kGy, 6 kGy, 9 kGy, 12 kGy, 15 kGy and 30 kGy absorbed doses. After irradiation processing, the ametryne highest reduction rate occurs at low doses of radiation: at 6 kGy more than 85-90% of all ametryne compounds were removed. Two products of incomplete degradation of ametryne were identified as s-triazyne isomers. However, further work is needed in order to fully understand the ametryne degradation mechanisms the degradation yield of ametryne depends on its initial concentration and the process seems to be more efficient at higher concentrations. (author)

  2. Bacteria-mediated bisphenol A degradation.

    Science.gov (United States)

    Zhang, Weiwei; Yin, Kun; Chen, Lingxin

    2013-07-01

    Bisphenol A (BPA) is an important monomer in the manufacture of polycarbonate plastics, food cans, and other daily used chemicals. Daily and worldwide usage of BPA and BPA-contained products led to its ubiquitous distribution in water, sediment/soil, and atmosphere. Moreover, BPA has been identified as an environmental endocrine disruptor for its estrogenic and genotoxic activity. Thus, BPA contamination in the environment is an increasingly worldwide concern, and methods to efficiently remove BPA from the environment are urgently recommended. Although many factors affect the fate of BPA in the environment, BPA degradation is mainly depended on the metabolism of bacteria. Many BPA-degrading bacteria have been identified from water, sediment/soil, and wastewater treatment plants. Metabolic pathways of BPA degradation in specific bacterial strains were proposed, based on the metabolic intermediates detected during the degradation process. In this review, the BPA-degrading bacteria were summarized, and the (proposed) BPA degradation pathway mediated by bacteria were referred.

  3. Y-Irradiation Degradation of Methamidophos

    Institute of Scientific and Technical Information of China (English)

    ZHAO Renbang; BAO Huaying; XIA Lingyun

    2009-01-01

    The irradiation degradation of methamidophos in aqueous solutions by 60Co-γ rays was investigated.The effects of absorbed doses,saturated gas,and the additive of H2O2 on the degradation were also studied.The results showed that the increased with the increase of the irradiation dosage.At certain irradiation dosage,methamidophos could be degraded completely.The degradation rate of methamidophos in the solution saturated with oxygen was higher than those saturated with other gases,which reached 100% when the absorbed dose was 8 kGy.H2O2 degraded methamidophos slowly when it was used alone,but could accelerate the degradation obviously when it was used with irradiation together.

  4. Kinetic study and mechanism of Niclosamide degradation

    Science.gov (United States)

    Zaazaa, Hala E.; Abdelrahman, Maha M.; Ali, Nouruddin W.; Magdy, Maimana A.; Abdelkawy, M.

    2014-11-01

    A spectrophotometric kinetic study of Niclosamide alkaline degradation as a function of drug concentration, alkaline concentration and temperature has been established utilizing double divisor-ratio spectra spectrophotometric method. The developed method allowed determination of Niclosamide in presence of its alkaline degradation products; namely; 2-chloro-4-nitro aniline (DEG I) and 5-chloro salicylic acid (DEG II) with characterization of its degradation mechanism. It was found that degradation kinetic of Niclosamide followed pseudo-first order under the established experimental conditions with a degradation rate constant (k) of 0.0829 mol/h and half life (t1/2) of 8.35 h. The overall degradation rate constant as a function of the temperature under the given conditions obeyed Arrhenius equation where the activation energy was calculated to be 3.41 kcal/mol.

  5. Microbial degradation of pyridine using Pseudomonas sp. and isolation of plasmid responsible for degradation.

    Science.gov (United States)

    Mohan, S Venkata; Sistla, Srinivas; Guru, R Kumar; Prasad, K Krishna; Kumar, C Suresh; Ramakrishna, S V; Sarma, P N

    2003-01-01

    Pseudomonas (PI2) capable of degrading pyridine was isolated from the mixed population of the activated sludge unit which was being used for treating complex effluents, the strain was characterized. Aerobic degradation of pyridine was studied with the isolated strain and the growth parameters were evaluated. Pyridine degradation was further conformed by chromatography (HPLC) analysis. The process parameters like biomass growth and dissolved oxygen consumption were monitored during pyridine degradation. In order to conform with the plasmid capability to degrade pyridine, the requisite plasmid was isolated and transferred to DH 5alpha Escherichia coli. The subsequent biodegradation studies revealed the ability of the transformed plasmid capability to degrade the pyridine.

  6. ENHANCEMENT OF RESISTANCE TO OXIDATIVE DEGRADATION OF NATURAL RUBBER THROUGH LATEX DEGRADATION

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    A fully characterised natural rubber latex was subjected to mechanical degradation by stirring at intervals. The resistance to oxidative degradation of the different samples were studied by measuring the Plasticity retention indices (PRI).The results show that there is an enhancement of the PRI from 57% for the undegraded rubber to 79% for the one-hour degraded sample. Further degradation resulted in decrease of PRI as time of degradation increased. Therefore, the one-hour degraded sample is a special rubber with high oxidation resistance which is of great importance in engineering.

  7. Microbial degradation of petroleum hydrocarbons.

    Science.gov (United States)

    Varjani, Sunita J

    2017-01-01

    Petroleum hydrocarbon pollutants are recalcitrant compounds and are classified as priority pollutants. Cleaning up of these pollutants from environment is a real world problem. Bioremediation has become a major method employed in restoration of petroleum hydrocarbon polluted environments that makes use of natural microbial biodegradation activity. Petroleum hydrocarbons utilizing microorganisms are ubiquitously distributed in environment. They naturally biodegrade pollutants and thereby remove them from the environment. Removal of petroleum hydrocarbon pollutants from environment by applying oleophilic microorganisms (individual isolate/consortium of microorganisms) is ecofriendly and economic. Microbial biodegradation of petroleum hydrocarbon pollutants employs the enzyme catalytic activities of microorganisms to enhance the rate of pollutants degradation. This article provides an overview about bioremediation for petroleum hydrocarbon pollutants. It also includes explanation about hydrocarbon metabolism in microorganisms with a special focus on new insights obtained during past couple of years.

  8. Bacterial Degradation of Aromatic Compounds

    Directory of Open Access Journals (Sweden)

    Qing X. Li

    2009-01-01

    Full Text Available Aromatic compounds are among the most prevalent and persistent pollutants in the environment. Petroleum-contaminated soil and sediment commonly contain a mixture of polycyclic aromatic hydrocarbons (PAHs and heterocyclic aromatics. Aromatics derived from industrial activities often have functional groups such as alkyls, halogens and nitro groups. Biodegradation is a major mechanism of removal of organic pollutants from a contaminated site. This review focuses on bacterial degradation pathways of selected aromatic compounds. Catabolic pathways of naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, and benzo[a]pyrene are described in detail. Bacterial catabolism of the heterocycles dibenzofuran, carbazole, dibenzothiophene, and dibenzodioxin is discussed. Bacterial catabolism of alkylated PAHs is summarized, followed by a brief discussion of proteomics and metabolomics as powerful tools for elucidation of biodegradation mechanisms.

  9. The Degraded Poisson Wiretap Channel

    CERN Document Server

    Laourine, Amine

    2010-01-01

    Providing security guarantees for wireless communication is critically important for today's applications. While previous work in this area has concentrated on radio frequency (RF) channels, providing security guarantees for RF channels is inherently difficult because they are prone to rapid variations due small scale fading. Wireless optical communication, on the other hand, is inherently more secure than RF communication due to the intrinsic aspects of the signal propagation in the optical and near-optical frequency range. In this paper, secure communication over wireless optical links is examined by studying the secrecy capacity of a direct detection system. For the degraded Poisson wiretap channel, a closed-form expression of the secrecy capacity is given. A complete characterization of the general rate-equivocation region is also presented. For achievability, an optimal code is explicitly constructed by using the structured code designed by Wyner for the Poisson channel. The converse is proved in two dif...

  10. Permafrost degradation in West Greenland

    DEFF Research Database (Denmark)

    Foged, Niels Nielsen; Ingeman-Nielsen, Thomas

    2012-01-01

    Important aspects of civil engineering in West Greenland relate to the presence of permafrost and mapping of the annual and future changes in the active layer due to the ongoing climatically changes in the Arctic. The Arctic Technology Centre (ARTEK) has worked more than 10 years on this topic......, Kangerlussuaq, Sisimiut and Nuuk. They are situated in continuous, discontinuous and sporadic permafrost zones. We will show examples of detoriation of permafrost related to present local scale climate observations and large scale climate and permafrost simulations modeled numerically with the GIPL model driven...... by HIRHAM climate projections for Greenland up to 2075. The engineering modelling is based on a risk assessment methodology based on a flow diagram which classify the risk of permafrost degradation causing settlement and stability problems for buildings and infrastructures based on relatively simple...

  11. CELLULOSE DEGRADATION BY OXIDATIVE ENZYMES

    Directory of Open Access Journals (Sweden)

    Maria Dimarogona

    2012-09-01

    Full Text Available Enzymatic degradation of plant biomass has attracted intensive research interest for the production of economically viable biofuels. Here we present an overview of the recent findings on biocatalysts implicated in the oxidative cleavage of cellulose, including polysaccharide monooxygenases (PMOs or LPMOs which stands for lytic PMOs, cellobiose dehydrogenases (CDHs and members of carbohydrate-binding module family 33 (CBM33. PMOs, a novel class of enzymes previously termed GH61s, boost the efficiency of common cellulases resulting in increased hydrolysis yields while lowering the protein loading needed. They act on the crystalline part of cellulose by generating oxidized and non-oxidized chain ends. An external electron donor is required for boosting the activity of PMOs. We discuss recent findings concerning their mechanism of action and identify issues and questions to be addressed in the future.

  12. Controlled enzyme catalyzed heteropolysaccharide degradation

    DEFF Research Database (Denmark)

    Rasmussen, Louise Enggaard

    The work presented in this PhD thesis has provided a better understanding of the enzyme kinetics and quantitative phenomena of the hydrolysis of xylan substrates by selected pure enzyme preparations. Furthermore, the options for producing specific substituted xylooligosaccharides from selected...... substrates by specific xylanase treatment have been examined. The kinetics of the enzymatic degradation of water-extractable wheat arabinoxylan (WE-AX) during designed treatments with selected monocomponent enzymes was investigated by monitoring the release of xylose and arabinose. The results of different...... between -xylosidase and the α-L-arabinofuranosidases on the xylose release were low as compared to the effect of xylanase addition with β-xylosidase, which increased the xylose release by ~25 times in 30 minutes. At equimolar addition levels of the four enzymes, the xylanase activity was thus rate...

  13. Durability Improvements Through Degradation Mechanism Studies

    Energy Technology Data Exchange (ETDEWEB)

    Borup, Rodney L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mukundan, Rangachary [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Spernjak, Dusan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Baker, Andrew M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lujan, Roger W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Langlois, David Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ahluwalia, Rajesh [Argonne National Lab. (ANL), Argonne, IL (United States); Papadia, D. D. [Argonne National Lab. (ANL), Argonne, IL (United States); Weber, Adam Z. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kusoglu, Ahmet [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Shi, Shouwnen [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); More, K. L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Grot, Steve [Ion Power, New Castle, DE (United States)

    2015-08-03

    The durability of polymer electrolyte membrane (PEM) fuel cells is a major barrier to the commercialization of these systems for stationary and transportation power applications. By investigating cell component degradation modes and defining the fundamental degradation mechanisms of components and component interactions, new materials can be designed to improve durability. To achieve a deeper understanding of PEM fuel cell durability and component degradation mechanisms, we utilize a multi-institutional and multi-disciplinary team with significant experience investigating these phenomena.

  14. Thermal degradation of organo-soluble polyimides

    Institute of Scientific and Technical Information of China (English)

    黄俐研; 史燚; 金熹高

    1999-01-01

    The thermal degradation behavior of two organo-soluble polyimides was investigated by high resolution pyrolysis-gas chromatography/mass spectrometry. The pyrolyzates of the polymers at various temperatures were identified and characterized quantitatively. The relationship between the polymer structure and pyrolyzate distribution was discussed. The kinetic parameters of the thermal degradation were calculated based on thermogravimetric measurements. Finally, the thermal degradation mechanism for the polymers was suggested.

  15. CLAD DEGRADATION - FEPS SCREENING ARGUMENTS

    Energy Technology Data Exchange (ETDEWEB)

    R. Schreiner

    2004-10-21

    The purpose of this report is to evaluate and document the screening of the clad degradation features, events, and processes (FEPs) with respect to modeling used to support the Total System Performance Assessment-License Application (TSPA-LA). This report also addresses the effect of certain FEPs on both the cladding and the commercial spent nuclear fuel (CSNF), DOE-owned spent nuclear fuel (DSNF), and defense high-level waste (DHLW) waste forms, as appropriate to address the effects on multiple materials and both components (FEPs 2.1.09.09.0A, 2.1.09.11.0A, 2.1.11.05.0A, 2.1.12.02.0A, and 2.1.12.03.0A). These FEPs are expected to affect the repository performance during the postclosure regulatory period of 10,000 years after permanent closure. Table 1-1 provides the list of cladding FEPs, including their screening decisions (include or exclude). The primary purpose of this report is to identify and document the analysis, screening decision, and TSPA-LA disposition (for included FEPs) or screening argument (for excluded FEPs) for these FEPs related to clad degradation. In some cases, where a FEP covers multiple technical areas and is shared with other FEP reports, this report may provide only a partial technical basis for the screening of the FEP. The full technical basis for shared FEPs is addressed collectively by the sharing FEP reports. The screening decisions and associated TSPA-LA dispositions or screening arguments from all of the FEP reports are cataloged in a project-specific FEPs database.

  16. On-Orbit Degradation of Solar Instruments

    Science.gov (United States)

    BenMoussa, A.; Gissot, S.; Schühle, U.; Del Zanna, G.; Auchère, F.; Mekaoui, S.; Jones, A. R.; Walton, D.; Eyles, C. J.; Thuillier, G.; Seaton, D.; Dammasch, I. E.; Cessateur, G.; Meftah, M.; Andretta, V.; Berghmans, D.; Bewsher, D.; Bolsée, D.; Bradley, L.; Brown, D. S.; Chamberlin, P. C.; Dewitte, S.; Didkovsky, L. V.; Dominique, M.; Eparvier, F. G.; Foujols, T.; Gillotay, D.; Giordanengo, B.; Halain, J. P.; Hock, R. A.; Irbah, A.; Jeppesen, C.; Judge, D. L.; Kretzschmar, M.; McMullin, D. R.; Nicula, B.; Schmutz, W.; Ucker, G.; Wieman, S.; Woodraska, D.; Woods, T. N.

    2013-11-01

    We present the lessons learned about the degradation observed in several space solar missions, based on contributions at the Workshop about On-Orbit Degradation of Solar and Space Weather Instruments that took place at the Solar Terrestrial Centre of Excellence (Royal Observatory of Belgium) in Brussels on 3 May 2012. The aim of this workshop was to open discussions related to the degradation observed in Sun-observing instruments exposed to the effects of the space environment. This article summarizes the various lessons learned and offers recommendations to reduce or correct expected degradation with the goal of increasing the useful lifespan of future and ongoing space missions.

  17. On-Orbit Degradation of Solar Instruments

    CERN Document Server

    BenMoussa, A; Schühle, U; Del Zanna, G; Auchère, F; Mekaoui, S; Jones, A R; Walton, D; Eyles, C J; Thuillier, G; Seaton, D; Dammasch, I E; Cessateur, G; Meftah, M; Andretta, V; Berghmans, D; Bewsher, D; Bolsée, D; Bradley, L; Brown, D S; Chamberlin, P C; Dewitte, S; Didkovsky, L V; Dominique, M; Eparvier, F G; Foujols, T; Gillotay, D; Giordanengo, B; Halain, J -P; Hock, R A; Irbah, A; Jeppesen, C; Judge, D L; Kretzschmar, M; McMullin, D R; Nicula, B; Schmutz, W; Ucker, G; Wieman, S; Woodraska, D; Woods, T N; 10.1007/s11207-013-0290-z

    2013-01-01

    We present the lessons learned about the degradation observed in several space solar missions, based on contributions at the Workshop about On-Orbit Degradation of Solar and Space Weather Instruments that took place at the Solar Terrestrial Centre of Excellence (Royal Observatory of Belgium) in Brussels on 3 May 2012. The aim of this workshop was to open discussions related to the degradation observed in Sun-observing instruments exposed to the effects of the space environment. This article summarizes the various lessons learned and offers recommendations to reduce or correct expected degradation with the goal of increasing the useful lifespan of future and ongoing space missions.

  18. Photovoltaic Degradation Rates -- An Analytical Review

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, D. C.; Kurtz, S. R.

    2012-06-01

    As photovoltaic penetration of the power grid increases, accurate predictions of return on investment require accurate prediction of decreased power output over time. Degradation rates must be known in order to predict power delivery. This article reviews degradation rates of flat-plate terrestrial modules and systems reported in published literature from field testing throughout the last 40 years. Nearly 2000 degradation rates, measured on individual modules or entire systems, have been assembled from the literature, showing a median value of 0.5%/year. The review consists of three parts: a brief historical outline, an analytical summary of degradation rates, and a detailed bibliography partitioned by technology.

  19. Simulating Degradation Data for Prognostic Algorithm Development

    Data.gov (United States)

    National Aeronautics and Space Administration — PHM08 Challenge Dataset is now publicly available at the NASA Prognostics Respository + Download INTRODUCTION - WHY SIMULATE DEGRADATION DATA? Of various challenges...

  20. Residual stress simulation of circumferential welded joints

    Directory of Open Access Journals (Sweden)

    Melicher R.

    2007-11-01

    Full Text Available Residual stresses are an important consideration in the component integrity and life assessment of welded structure. The welding process is very complex time dependent physical phenomenon with material nonlinearity. The welding is a thermal process with convection between fluid flow and welding body, between welding bodyand environment. Next type of boundary conditions is radiation and thermo-mechanical contact on the outer surface of gas pipe in the near of weld. The temperature variation so obtained is utilised to find the distribution of the stress field.In this paper, a brief review of weld simulation and residual stress modelling using the finite element method (FEM by commercial software ANSYS is presented. Thermo-elastic-plastic formulations using a von Mises yield criterion with nonlinear kinematics hardening has been employed. Residual axial and hoop stresses obtained from the analysis have been shown. The commercial FEM code ANSYS was used for coupled thermalmechanical analysis.

  1. Accelerated propor tional degradation hazards-odds model in accelerated degradation test

    Institute of Scientific and Technical Information of China (English)

    Tingting Huang; Zhizhong Li

    2015-01-01

    An accelerated proportional degradation hazards-odds model is proposed. It is a non-parametric model and thus has path-free and distribution-free properties, avoiding the errors caused by faulty assumptions of degradation paths or distribution of degra-dation measurements. It is established based on a link function which combines the degradation cumulative hazard rate function and the degradation odds function through a transformation pa-rameter, and this makes the accelerated proportional degradation hazards model and the accelerated proportional degradation odds model special cases of it. Hypothesis tests are discussed, and the proposed model is applicable when some model assumptions are satisfied. This model is utilized to estimate the reliability of minia-ture bulbs under low stress levels based on the degradation data obtained under high stress levels to validate the effectiveness of this model.

  2. Mechanisms of humic substances degradation by fungi

    Science.gov (United States)

    Chen, Y.; Hadar, Y.; Grinhut, T.

    2012-04-01

    Humic substances (HS) are formed by secondary synthesis reactions (humification) during the decay process and transformation of biomolecules originating from plants and other dead organisms. In nature, HS are extremely resistant to biological degradation. Thus, these substances are major components in the C cycle and in the biosphere and therefore, the understanding of the process leading to their formation and transformation and degradation is vital. Fungi active in the decomposition process of HS include mainly ascomycetes and basidiomycetes that are common in the upper layer of forest and grassland soils. Many basidiomycetes belong to the white-rot fungi (WRF) and litter-decomposing fungi (LDF). These fungi are considered to be the most efficient lignin degraders due to their nonspecific oxidizing enzymes: manganese peroxidase (MnP), lignin peroxidase (LiP) and laccase. Although bacteria dominate compost and participate in the turnover of HS, their ability to degrade stable macromolecules such as lignin and HS is limited. The overall objectives of this research were to corroborate biodegradation processes of HS by WRF. The specific objectives were: (i) To isolate, identify and characterize HS degrading WRF from biosolids (BS) compost; (ii) To study the biodegradation process of three types of HS, which differ in their structure, by WRF isolated from BS compost; and (iii) To investigate the mechanisms of HA degradation by WRF using two main approaches: (a) Study the physical and chemical analyses of the organic compounds obtained from direct fungal degradation of HA as well as elucidation of the relevant enzymatic reactions; and (b) Study the enzymatic and biochemical mechanisms involved during HA degradation. In order to study the capability of fungi to degrade HS, seventy fungal strains were isolated from biosolids (BS) compost. Two of the most active fungal species were identified based on rDNA sequences and designated Trametes sp. M23 and Phanerochaetesp., Y6

  3. Aflatoxin B₁ degradation by a Pseudomonas strain.

    Science.gov (United States)

    Sangare, Lancine; Zhao, Yueju; Folly, Yawa Minnie Elodie; Chang, Jinghua; Li, Jinhan; Selvaraj, Jonathan Nimal; Xing, Fuguo; Zhou, Lu; Wang, Yan; Liu, Yang

    2014-10-23

    Aflatoxin B1 (AFB1), one of the most potent naturally occurring mutagens and carcinogens, causes significant threats to the food industry and animal production. In this study, 25 bacteria isolates were collected from grain kernels and soils displaying AFB1 reduction activity. Based on its degradation effectiveness, isolate N17-1 was selected for further characterization and identified as Pseudomonas aeruginosa. P. aeruginosa N17-1 could degrade AFB₁, AFB₂ and AFM₁ by 82.8%, 46.8% and 31.9% after incubation in Nutrient Broth (NB) medium at 37 °C for 72 h, respectively. The culture supernatant of isolate N17-1 degraded AFB₁ effectively, whereas the viable cells and intra cell extracts were far less effective. Factors influencing AFB1 degradation by the culture supernatant were investigated. Maximum degradation was observed at 55 °C. Ions Mn²⁺ and Cu²⁺ were activators for AFB1 degradation, however, ions Mg²⁺, Li⁺, Zn²⁺, Se²⁺, Fe³⁺ were strong inhibitors. Treatments with proteinase K and proteinase K plus SDS significantly reduced the degradation activity of the culture supernatant. No degradation products were observed based on preliminary LC-QTOF/MS analysis, indicating AFB₁ was metabolized to degradation products with chemical properties different from that of AFB₁. The results indicated that the degradation of AFB₁ by P. aeruginosa N17-1 was enzymatic and could have a great potential in industrial applications. This is the first report indicating that the isolate of P. aeruginosa possesses the ability to degrade aflatoxin.

  4. Biochar degradation in different soils

    Science.gov (United States)

    Wilske, B.; Bai, M.; Eckhardt, C.; Kammann, C.; Kraft, P.; Bach, M.; Frede, H.-G.; Breuer, L.

    2012-04-01

    Current expectations in biochar products (BC) are numerous, e.g., including improved soil fertility & plant growth, support to combat desertification, and an increase in the carbon sequestration of soils. Costs for biochar production & application must be covered by a positive budget of benefits, which may crucially depend on the residence time (or half life T1/2, yr) of BC in soils. The objective of the present study was to assess the biodegradation rates of BC in different soils by means of a cost-efficient and standardized laboratory method. Investigated BC were from the source material of the C4 plant Miscanthus, and converted via (1) pyrolysis (pyrBC) and (2) hydrothermal carbonization (htcBC). The high-labelling of the educt allowed the quantification of degradation by measurement of the 13CO2 efflux. The pyrBC and htcBC were mixed with four different agricultural soils ranging in texture from sand to loam and in soil organic carbon (SOC) from 0.63% to 2.53%. Four samples of each BC-soil combination (1% BC wt/wt in a 300-g sample mixture) and soil-only reference were incubated in 1-L glass bottles at 40% water holding capacity and 25° C. Biodegradation of BC was monitored weekly over a period of 7 months using an automated open-dynamic chamber system. The system couples the batch of samples to microprocessor- controlled valves, by which flushing is provided for the batch, while individual samples are consecutively connected through to a wavelength scan cavity ring down spectrometer (WS-CRDS). Net 13CO2 efflux from BC was obtained by subtracting the 13CO2 efflux from "soil-only" samples. T1/2 was calculated based on the ln(k)-based algorithm recently suggested by Zimmerman et al. (2010). Results show an orders-of-magnitude larger T1/2 of BC in poor sandy soil than in SOC-richer soils (T1/2 up to 106 yrs) but not a statistically clear trend of biodegradability along the four-point SOC gradient. This was similar in both BC types, although T1/2 was generally

  5. Photo-degradation of imidazolium ionic liquids

    OpenAIRE

    Katoh, Ryuzi; Takahashi, Kenji

    2009-01-01

    Degradation of imidazolium ionic liquid, [bmim+][TFSA-] and iodide solution of [bmim+][TFSA-] by UV-laser irradiation has been studied through ground-state absorption and transient absorption spectroscopy. We found that excited state [bmim+]* undergoes degradation efficiently. © 2009 Elsevier Ltd. All rights reserved.

  6. Genetic engineering of sulfur-degrading Sulfolobus

    Energy Technology Data Exchange (ETDEWEB)

    Ho, N.W.Y.

    1991-01-01

    The objectives of the proposed research is to first establish a plasmid-mediated genetic transformation system for the sulfur degrading Sulfolobus, and then to clone and overexpress the genes encoding the organic-sulfur-degrading enzymes from Sulfolobus- as well as from other microorganisms, to develop a Sulfolobus-based microbial process for the removal of both organic and inorganic sulfur from coal.

  7. Photolytic degradation of decabromodiphenyl ethane (DBDPE).

    Science.gov (United States)

    Wang, Jing; Chen, Shejun; Nie, Xin; Tian, Mi; Luo, Xiaojun; An, Taicheng; Mai, Bixian

    2012-10-01

    The photolytic degradation of decabromodiphenyl ethane (DBDPE), an alternative flame retardant to decabromodiphenyl ether, was investigated in a variety of matrixes (n-hexane, tetrahydrofuran, methanol/water, humic acid/water, and silica gel) by irradiation under ultraviolet light and in n-hexane under natural light. Photolytic degradation of DBDPE occurs in all the matrixes investigated within the irradiation period (n-hexane (t(1/2)=16.6 min)>humic acid/water (30silica gel (t(1/2)=75.9 min)>methanol/water (t(1/2)>240 min). The reaction in tetrahydrofuran, n-hexane, and silica gel matrixes can be described by the pseudo first order kinetics. Nevertheless, the matrixes have little effect on the degradation product distributions of DBDPE. A numbers of debrominated intermediates were identified. The degradation involves the initial formation of nona-BDPEs and the subsequent decomposition of these congeners to lower brominated congeners (octa- and hepta-BDPEs) within the irradiation time. To our knowledge, the present work is the first attempt to investigate the photolytic degradation kinetics and the identification of intermediates, as well as the degradation mechanism, during the degradation of DBDPE. Further research is needed to understand the photolytic degradation pattern of DBDPE in the natural environment.

  8. Degradation mechanisms in organic photovoltaic devices

    NARCIS (Netherlands)

    Grossiord, N.; Kroon, J.M.; Andriessen, H.A.J.M.; Blom, P.W.M.

    2012-01-01

    In the present review, the main degradation mechanisms occurring in the different layer stacking (i.e. photoactive layer, electrode, encapsulation film, interconnection) of polymeric organic solar cells and modules are discussed. Bulk and interfacial, as well as chemical and physical degradation mec

  9. Microbial Degradation of Indole and Its Derivatives

    Directory of Open Access Journals (Sweden)

    Pankaj Kumar Arora

    2015-01-01

    Full Text Available Indole and its derivatives, including 3-methylindole and 4-chloroindole, are environmental pollutants that are present worldwide. Microbial degradation of indole and its derivatives can occur in several aerobic and anaerobic pathways; these pathways involve different known and characterized genes. In this minireview, we summarize and explain the microbial degradation of indole, indole-3-acetic acid, 4-chloroindole, and methylindole.

  10. Environmental Degradation of High Temperature Composites

    Science.gov (United States)

    1992-04-01

    A study was performed to assess the effect of galvanic corrosion phenomena on the strength of graphite/bismaleimide( BMI ) composites . The results...indicate that degradation occurred in BMI composites galvanically coupled to aluminum alloys. The mechanism responsible for the degradation involves

  11. Numerical Simulation of Flow Field in End Face Seal with Circumferential Waviness%端面周向波度密封中流场的数值模拟

    Institute of Scientific and Technical Information of China (English)

    孙赫; 张秋翔; 蔡纪宁; 李双喜

    2011-01-01

    建立端面周向波度密封密封端面间液膜流场的数值模型,采用计算流体力学软件FLUENT对密封间隙中的液膜进行三维数值模拟,得到液膜流场的压力分布,求得密封的泄漏量、开启力和刚度等密封特性参数,分析密封几何参数(如波幅、波数、密封环坝区的宽度与密封环宽度之比)对密封性能的影响.结果表明:随着液膜厚度的增加,开启力减小,泄漏量增大;密封几何参数对密封特性参数的影响存在一定的规律,如波幅越大、波数越多,密封环端面的流体动压效应越明显,而随密封环坝区的宽度与密封环宽度之比的增加,开启力、泄漏量和刚度都减小.%A theoretical analysis model of fluid film flow between the seal faces was established for the end face seal with circumferential waviness. By using the hydromechanics software FLUENT, a three-dimensional numerical simulation was performed for the liquid film of the seal gap, the pressure distribution of the liquid film flow was got, and the seal characteristic parameters, such as leakage, opening force and stiffness of seal were obtained. The effect of seal geometric parameters, such as wave amplitude, wave number and the rate of breadth of seal dam zone and seal breadth, on seal performance was analyzed. Results show that with the increase of fluid film thickness, the opening force is reduced and the leakage increased. There is certain law existed between the seal geometric parameters and the seal characteristic parameters, that there is obvious hydrodynamic pressure effect in seal ring end face for the seal with big wave amplitude and more wave number. With the increase of the rate of breadth of seal dam zone and seal breadth, the opening force, leakage and stiffness are reduced.

  12. Degradation of ochratoxin a by Brevibacterium species.

    Science.gov (United States)

    Rodriguez, Hector; Reveron, Ines; Doria, Francesca; Costantini, Antonella; De Las Rivas, Blanca; Muňoz, Rosario; Garcia-Moruno, Emilia

    2011-10-12

    The ability to degrade ochratoxin A was studied in different bacteria with a well-known capacity to transform aromatic compounds. Strains belonging to Rhodococcus, Pseudomonas, and Brevibacterium genera were grown in liquid synthetic culture medium containing ochratoxin A. Brevibacterium spp. strains showed 100% degradation of ochratoxin A. Ochratoxin α was detected and identified by high-performance liquid chromatography-mass spectrometry (HPLC-MS) as a degradation product in the cell-free supernatants. The degradation of ochratoxin A is of public concern for food and environmental safety, because it could contribute to the development of new biological ochratoxin A detoxification systems in foodstuffs. In this study, the degradation of ochratoxin A by bacteria belonging to the food chain was demonstrated for the first time.

  13. [Photochemical degradation of chlorpyrifos in water].

    Science.gov (United States)

    Wu, Xiangwei; Hua, Rimao; Tang, Feng; Li, Xuede; Cao, Haiqun; Yue, Yongde

    2006-07-01

    In this paper, the effects of different light sources, temperature, pH, and water quality on the photochemical degradation of clilorpyrifos in water were examined under natural and simulated solar irradiation. The results showed that the photochemical degradation of chlorpyrifos in water followed the first order reaction, and its half-life was 0.62, 6.92, 19.74 and 22.50 h under high pressure mercury lamp (HPML), xenon lamp (XL), ultraviolet lamp (UV), and sunlight (SL) irradiation, respectively. Temperature had a significant effect on the degradation rate of chlorpyrifos, which was increased with increasing temperature and reached the maximum at 35 degrees C. The degradation rate of chlorpyrifos was stable both in acid and in neutral buffer solution, but enhanced in alkaline buffer solution. Water quality also had a significant effect, with a decreasing degradation rate of chlorpyrifos in the sequence of distilled water > tap water > river water > lake wate > paddy water.

  14. Afforestation of degraded grass land

    Energy Technology Data Exchange (ETDEWEB)

    Basappa, B.

    1983-01-01

    The suitability of 11 species was tested for planting on degraded land at Kogilemane in Belur Taluk, Karnataka. The soil was alkaline with no humus, litter or topsoil. The original vegetation was grass with the stemless palm Phoenix acaulis, still present at 600 plants per acre. Seedlings 4-6 months old and raised in polythene bags were planted in pits in July 1981; Bambusa vulgaris was planted as 8-month-old cuttings. No fertilizer was applied. The most successful species after the first season was Acacia auriculiformis. Satisfactory survival and growth were also obtained with Cassia siamea, Peltoforum ferruginum, Leucaena leucocephala (although this was later heavily damaged by wild rabbits) and Toona ciliata. The bamboo survived well but there was no culm formation during the experiment. In 1982 only 3 of the species were tested: A. auriculiformis, L. leucocephala (because of its fast growth rate) and Casuarina equisetifolia (which performed badly in 1981 but is suited to alkaline soils). All 3 species performed satisfactorily.

  15. Degradation of triclocarban by a triclosan-degrading Sphingomonas sp. strain YL-JM2C.

    Science.gov (United States)

    Mulla, Sikandar I; Hu, Anyi; Wang, Yuwen; Sun, Qian; Huang, Shir-Ly; Wang, Han; Yu, Chang-Ping

    2016-02-01

    Bacterial degradation plays a vital role in determining the environmental fate of micropollutants like triclocarban. The mechanism of triclocarban degradation by pure bacterium is not yet explored. The purpose of this study was to identify metabolic pathway that might be involved in bacterial degradation of triclocarban. Triclosan-degrading Sphingomonas sp. strain YL-JM2C was first found to degrade up to 35% of triclocarban (4 mg L(-1)) within 5 d. Gas chromatography-mass spectrometry detected 3,4-dichloroaniline, 4-chloroaniline and 4-chlorocatechol as the major metabolites of the triclocarban degradation. Furthermore, total organic carbon results confirmed that the intermediates, 3,4-dichloroaniline (4 mg L(-1)) and 4-chloroaniline (4 mg L(-1)) could be degraded up to 77% and 80% by strain YL-JM2C within 5 d.

  16. Degradation of Soil Nutrients in Southeast China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A total of 2190 soil nutrient data in the Second National Soil Survey of China were collected to assess the degradation of soil nutrients in the hilly region of Southeast China. The definition of soil nutrient degradation is suggested firstly, then the evaluation criteria are set up and the current status of degradation of red soil and latosol is assessed. The percentages of areas in four grades of soil nutrient degradation, i.e., slightly deficient, medium deficient, severely deficient and extremely deficient, were 21.3%, 43.3%, 16.2% and 3.0% for soil total N; 0.7%, 6.4%, 16.7% and 76.2% for soil available P; and 25.4%, 26.3%, 8.6% and 5.0% for soil available K, respectively. The severity of soil nutrient degradation was in the order of P > N > K. The major factors leading to the degradation of soil nutrients in quantity include soil erosion, leaching and the consumption by crops. And the principal factor affecting the degradation of soil nutrients in availability is the fixation of N, P and K, especially the fixation of phosphorus. The average amount of P fixed by soils is 408 mg kg-1, and upland soils can fix more P than paddy soils.

  17. Microbial Aspects of Anaerobic BTEX Degradation

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Combined with conventional methods, developments in both geochemical (delineation of redox processes) and molecular microbial methods (analysis of 16S rDNA genes and functional genes) have allowed us to study in details microorganisms and genes involved in the anaerobic degradation of benzene, toluene, ethylbenzene and xylene (BTEX) under specific redox conditions. This review summarizes recent research in this field. The potential for anaerobic BTEX degradation is widely spread. Specific groups of microorganisms appear to be involved in degradation under different redox conditions. Members of the Azoarcus/Thauera cluster perform BTEX degradation under denitrifying conditions, Geobacteraceae under Fe (III) reducing conditions and Desulfobacteriaceae under sulfate reducing conditions. The information so far obtained on biochemistry and molecular genetics of BTEX degradation indicates that each BTEX compound is funneled into the central benzyol-CoA pathway by a different peripheral pathway. The peripheral pathways of per BTEX compound show similarities among different physiological groups of microorganisms. We also describe how knowledge obtained on the microbial aspects of BTEX degradation can be used to enhance and monitor anaerobic BTEX degradation.

  18. Radiation degradation of alginate and chitosan

    Energy Technology Data Exchange (ETDEWEB)

    Nagasawa, Naotsugu; Mitomo, Hiroshi [Department of Biological and Chemical Engineering, Faculty of Engineering, Gunma University, Kiryu, Gunma (Japan); Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2000-03-01

    Alginate and chitosan were irradiated in solid or aqueous solution condition with Co{sup 60} gamma rays in the dose range of 20 to 500 kGy. Degradation was observed both in solid and solution conditions. The degradation in solution was remarkably greater than that in solid. For example, the molecular weight of alginate in 4%(w/v) solution decreased from 2 x 10{sup 5} for 0 kGy to 6 x 10{sup 3} for 50 kGy irradiation while the equivalent degradation by solid irradiation required 500 kGy. The activated species from irradiated water must be responsible for the degradation in solution. The degradation was also accompanied with the color change of alginate: the color became deep brown for highly degraded alginate. UV spectra showed a distinct absorption peak at 265 nm for colored alginates, increasing with dose. The fact that discoloration of colored alginate was caused on exposure to ozone suggests a formation of double bond in pyranose-ring by scission of glycosidic bond. Degradation behavior of chitosan in irradiation was almost the same as that of alginate. (author)

  19. Mycotoxin-degradation profile of Rhodococcus strains.

    Science.gov (United States)

    Cserháti, M; Kriszt, B; Krifaton, Cs; Szoboszlay, S; Háhn, J; Tóth, Sz; Nagy, I; Kukolya, J

    2013-08-16

    Mycotoxins are secondary fungal metabolites that may have mutagenic, carcinogenic, cytotoxic and endocrine disrupting effects. These substances frequently contaminate agricultural commodities despite efforts to prevent them, so successful detoxification tools are needed. The application of microorganisms to biodegrade mycotoxins is a novel strategy that shows potential for application in food and feed processing. In this study we investigated the mycotoxin degradation ability of thirty-two Rhodococcus strains on economically important mycotoxins: aflatoxin B1, zearalenone, fumonisin B1, T2 toxin and ochratoxin A, and monitored the safety of aflatoxin B1 and zearalenone degradation processes and degradation products using previously developed toxicity profiling methods. Moreover, experiments were performed to analyse multi-mycotoxin-degrading ability of the best toxin degrader/detoxifier strains on aflatoxin B1, zearalenone and T2 toxin mixtures. This enabled the safest and the most effective Rhodococcus strains to be selected, even for multi-mycotoxin degradation. We concluded that several Rhodococcus species are effective in the degradation of aromatic mycotoxins and their application in mycotoxin biodetoxification processes is a promising field of biotechnology.

  20. Degradation diagnostics for lithium ion cells

    Science.gov (United States)

    Birkl, Christoph R.; Roberts, Matthew R.; McTurk, Euan; Bruce, Peter G.; Howey, David A.

    2017-02-01

    Degradation in lithium ion (Li-ion) battery cells is the result of a complex interplay of a host of different physical and chemical mechanisms. The measurable, physical effects of these degradation mechanisms on the cell can be summarised in terms of three degradation modes, namely loss of lithium inventory, loss of active positive electrode material and loss of active negative electrode material. The different degradation modes are assumed to have unique and measurable effects on the open circuit voltage (OCV) of Li-ion cells and electrodes. The presumptive nature and extent of these effects has so far been based on logical arguments rather than experimental proof. This work presents, for the first time, experimental evidence supporting the widely reported degradation modes by means of tests conducted on coin cells, engineered to include different, known amounts of lithium inventory and active electrode material. Moreover, the general theory behind the effects of degradation modes on the OCV of cells and electrodes is refined and a diagnostic algorithm is devised, which allows the identification and quantification of the nature and extent of each degradation mode in Li-ion cells at any point in their service lives, by fitting the cells' OCV.

  1. Thermal Degradation of Lignocellulosic Fuels: Biopolymers Contribution

    OpenAIRE

    Leroy, Valérie; Leoni, Eric; Cancellieri, Dominique

    2010-01-01

    In wildland fire modelling and forest fuel hazard studies, the thermal degradation of the solid is a fundamental stage. Two ways are suitable: the first one considers the thermal degradation of the whole fuel giving a complex mixture of gas, tars and chars; the second one considers the thermal degradation as the sum of the contributions from the principal components of the fuel. Our aim was to verify the validity of the second approach. DSC analyses were performed in order to get the enthalpy...

  2. Kinetic Parameters of Thermal Degradation of Polymers

    Institute of Scientific and Technical Information of China (English)

    朱新生; 程嘉祺

    2003-01-01

    The derivative expressions between activation energy (E) and the temperature at the maximum mass loss rate(Tmax) and between activation energy (E) and exponent (N) were deduced in the light of Arrhenius theory. It was found that the increase of activation energy results in the decrease of exponent and the increase of Tmax. The kinetic parameters were involved in the analysis of the thermal degradation of several polymers. The degradation kinetics of these polymers well complied with the prediction of the derivative expressions for the polymer degradation with single mechanism dominated.

  3. CHANNEL WIDENING DURING DEGRADATION OF ALLUVIAL RIVERS

    Institute of Scientific and Technical Information of China (English)

    Guangqian WANG; Junqiang XIA

    2001-01-01

    This paper first describes the phenomenon of channel widening during degradation of alluvial rivers,explains the mechanisms of channel widening, and analyzes the stability of cohesive riverbank. Then a one-dimensional mathematical model is developed to simulate the transport of non-uniform suspended sediments, with a sub-model for the simulation of channel widening, and is used to study the process of channel widening during degradation. The effects of different incident flow and sediment conditions and different riverbank material characteristics on channel widening and bed degradation are compared.Finally, main factors that control the deformation processes are identified.

  4. Aqueous thermal degradation of gallic acid

    Science.gov (United States)

    Snow Boles, Jennifer; Crerar, David A.; Grissom, Grady; Key, Tonalee C.

    1988-02-01

    Aqueous thermal degradation experiments show gallic acid, a naturally occurring aromatic carboxylic compound, decomposes rapidly at temperatures between 105° and 150°C, with an activation energy of 22.9 or 27.8 kcal/ mole, depending on pH of the starting solution. Pyrogallol is the primary product identified, indicating degradation via decarboxylation and a carbanion transition state. Relatively rapid degradation of vanillic, phthalic, ellagic and tannic acids has also been observed, suggesting that these and perhaps other aromatic acids could be short-lived in deep formation waters.

  5. Autonomous valve for detection of biopolymer degradation

    DEFF Research Database (Denmark)

    Keller, Stephan Urs; Noeth, Nadine-Nicole; Fetz, Stefanie

    2009-01-01

    We present a polymer microvalve that allows the detection of biopolymer degradation without the need of external energy. The valve is based on a polymer container filled with a colored marker solution and closed by a thin lid. This structure is covered by a film of poly(L-lactide) and degradation...... of the biopolymer triggers the release of the color which is detected visually. The autonomous valve has potential for the fast testing of biopolymer degradation under various environmental conditions or by specific enzymes....

  6. ANTI-BIOFOULING BY DEGRADATION OF POLYMERS

    Institute of Scientific and Technical Information of China (English)

    Chun-feng Ma; Hong-jun Yang; Guang-zhao Zhang

    2012-01-01

    Copolymers of methyl methacrylate (MMA) and acrylate terminated poly(ethylene oxide-co-ethylene carbonate)(PEOC) macromonomer (PEOCA) were synthesized,and the degradation of the polymers was investigated by use of quartz crystal microbalance with dissipation (QCM-D).It is shown that the polymeric surface exhibits degradation in seawater depending on the content of the side chains.Field tests in seawater show that the surface constructed by the copolymer can effectively inhibit marine biofouling because it can be self-renewed due to degradation of the copolymer.

  7. Microfluidic Assessment of Frying Oil Degradation

    Science.gov (United States)

    Liu, Mei; Xie, Shaorong; Ge, Ji; Xu, Zhensong; Wu, Zhizheng; Ru, Changhai; Luo, Jun; Sun, Yu

    2016-06-01

    Monitoring the quality of frying oil is important for the health of consumers. This paper reports a microfluidic technique for rapidly quantifying the degradation of frying oil. The microfluidic device generates monodispersed water-in-oil droplets and exploits viscosity and interfacial tension changes of frying oil samples over their frying/degradation process. The measured parameters were correlated to the total polar material percentage that is widely used in the food industry. The results reveal that the steady-state length of droplets can be used for unambiguously assessing frying oil quality degradation.

  8. Rising population and environmental degradation.

    Science.gov (United States)

    Mitra, A

    Environmental degradation is becoming an increasingly ominous threat to the well-being of India's population, and excessive population growth is the primary cause of environmental deterioration. Population growth increases the need to produce consumer products and this need, in turn, intensifies the trend to over-exploit and misuse environmental resources. Efforts to control population growth through contraceptive technology and the expansion of family planning services and to control environmental deterioration via technology and management will meet with little success. A prerequisite for controlling these dual problems is the improvement of living conditions for the masses. Only when individuals acquire a sense of security and have the prospect of acquiring a share in the resources of the country will they be willing to conserve and renew resources and to limit their fertility. Viewed from this prospective, various factors and trends in India can be assessed as either negative or positive. Positive factors, i.e., those which enhance economic oppotunities and security for the general population, include the recent achievement of economic grothw in the country's agricultural and industrial sectors, the growth in technological knowledge, and the expansion of the rural and urban infrastructure. Negative factors include 1) the increase in income inequality, 2) the refusal to grant distributive justice to the masses, 3) the lack of education which impedes public understanding and awareness of environmental issues and promotes under utilization of community and social services, 4) the high unemployment rate which prevents individuals from developing a sense of responsibility and self respect; and 5) the refusal of the government to establish fuel policies to halt the growing problem of deforestation. Major environmental problems include pollution and congestion associated with the geographical concentration of industry; the destruction of the forests which leads to

  9. Hot carrier degradation in semiconductor devices

    CERN Document Server

    2015-01-01

    This book provides readers with a variety of tools to address the challenges posed by hot carrier degradation, one of today’s most complicated reliability issues in semiconductor devices.  Coverage includes an explanation of carrier transport within devices and book-keeping of how they acquire energy (“become hot”), interaction of an ensemble of colder and hotter carriers with defect precursors, which eventually leads to the creation of a defect, and a description of how these defects interact with the device, degrading its performance. • Describes the intricacies of hot carrier degradation in modern semiconductor technologies; • Covers the entire hot carrier degradation phenomenon, including topics such as characterization, carrier transport, carrier-defect interaction, technological impact, circuit impact, etc.; • Enables detailed understanding of carrier transport, interaction of the carrier ensemble with the defect precursors, and an accurate assessment of how the newly created defects imp...

  10. Bacterial degradation of monocyclic aromatic amines

    Directory of Open Access Journals (Sweden)

    Pankaj Kumar Arora

    2015-08-01

    Full Text Available Aromatic amines are an important group of industrial chemicals, which are widely used for manufacturing of dyes, pesticides, drugs, pigments, and other industrial products. These compounds have been considered highly toxic to human beings due to their carcinogenic nature. Three groups of aromatic amines have been recognized: monocyclic, polycyclic and heterocyclic aromatic amines. Bacterial degradation of several monocyclic aromatic compounds has been studied in a variety of bacteria, which utilizes monocyclic aromatic amines as their sole source of carbon and energy. Several degradation pathways have been proposed and the related enzymes and genes have also been characterized. Many reviews have been reviewed toxicity of monocyclic aromatic amines; however, there is lack of review on biodegradation of monocyclic aromatic amines. The aim of this review is to summarize bacterial degradation of monocyclic aromatic amines. This review will increase our current understanding of biochemical and molecular basis of bacterial degradation of monocyclic aromatic amines.

  11. Microbial assisted High Impact Polystyrene (HIPS) degradation.

    Science.gov (United States)

    Mohan, Arya J; Sekhar, Vini C; Bhaskar, Thallada; Nampoothiri, K Madhavan

    2016-08-01

    The efficacy of newly isolated Pseudomonas and Bacillus strains to degrade brominated High Impact Polystyrene (HIPS) was investigated. Viability of these cultures while using e-plastic as sole carbon source was validated through Triphenyl Tetrazolium Chloride (TTC). Four days incubation of HIPS emulsion with Bacillus spp. showed 94% reduction in turbidity and was 97% with Pseudomonas spp. Confirmation of degradation was concluded by HPLC, NMR, FTIR, TGA and weight loss analysis. NMR spectra of the degraded film revealed the formation of aliphatic carbon chain with bromine and its release. FTIR analysis of the samples showed a reduction in CH, CO and CN groups. Surface changes in the brominated HIPS film was visualized through SEM analysis. Degradation with Bacillus spp showed a weight loss of 23% (w/w) of HIPS film in 30days.

  12. Photocatalytic Degradation of Organic Contaminants in Water

    Science.gov (United States)

    Photocatalytic treatment of organics, including regulated and contaminants of emerging concern, has been an important area of this field. Details are provided on the mechanism of degradation, reaction intermediates, kinetics, and nanointerfacial adsorption phenomena. The degradat...

  13. Photochemical degradation of crude oil in seawater

    Institute of Scientific and Technical Information of China (English)

    YANG Guipeng; ZHANG Li; SUN Xiaojing; JING Weiwen

    2006-01-01

    Photochemical degradation of crude oil in seawater is an important issue in marine environmental protection and is studied in this work. Results showed that petroleum hydrocarbons could be effectively degraded by the irradiation of high-pressure mercury light or natural sunlight. Photochemical reaction was controlled by various factors including light source, aquatic medium, heavy metal ion and photo-sensitizer. The rate of photo-degradation was fast at the initial stage of exposure, exhibiting a first-order reaction kinetic behavior. However, after irradiation for a few hours, the concentration of water-soluble fraction (WSF) of petroleum hydrocarbons stabilized. For all experimental conditions, the range of the photo-degradation rate is from 0.001 3 to 0.005 7/min.

  14. Enzymatic degradation of multiwalled carbon nanotubes.

    Science.gov (United States)

    Zhao, Yong; Allen, Brett L; Star, Alexander

    2011-09-01

    Because of their unique properties, carbon nanotubes and, in particular, multiwalled carbon nanotubes (MWNTs) have been used for the development of advanced composite and catalyst materials. Despite their growing commercial applications and increased production, the potential environmental and toxicological impacts of MWNTs are not fully understood; however, many reports suggest that they may be toxic. Therefore, a need exists to develop protocols for effective and safe degradation of MWNTs. In this article, we investigated the effect of chemical functionalization of MWNTs on their enzymatic degradation with horseradish peroxidase (HRP) and hydrogen peroxide (H(2)O(2)). We investigated HRP/H(2)O(2) degradation of purified, oxidized, and nitrogen-doped MWNTs and proposed a layer-by-layer degradation mechanism of nanotubes facilitated by side wall defects. These results provide a better understanding of the interaction between HRP and carbon nanotubes and suggest an eco-friendly way of mitigating the environmental impact of nanotubes.

  15. Uncertainty Analysis for Photovoltaic Degradation Rates (Poster)

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, D.; Kurtz, S.; Hansen, C.

    2014-04-01

    Dependable and predictable energy production is the key to the long-term success of the PV industry. PV systems show over the lifetime of their exposure a gradual decline that depends on many different factors such as module technology, module type, mounting configuration, climate etc. When degradation rates are determined from continuous data the statistical uncertainty is easily calculated from the regression coefficients. However, total uncertainty that includes measurement uncertainty and instrumentation drift is far more difficult to determine. A Monte Carlo simulation approach was chosen to investigate a comprehensive uncertainty analysis. The most important effect for degradation rates is to avoid instrumentation that changes over time in the field. For instance, a drifting irradiance sensor, which can be achieved through regular calibration, can lead to a substantially erroneous degradation rates. However, the accuracy of the irradiance sensor has negligible impact on degradation rate uncertainty emphasizing that precision (relative accuracy) is more important than absolute accuracy.

  16. Sonophotocatalytic Degradation of Amines in Water

    Science.gov (United States)

    Verman, Mayank; Pankaj

    Hazardous effects of various amines, produced in the environment from the partial degradation of azo dyes and amino acids, adversely affect the quality of human life through water, soil and air pollution and therefore needed to be degraded. A number of such studies are already available in the literature, with or without the use of ultrasound, which have been summarized briefly. The sonochemical degradation of amines and in the combination with a photocatalyst, TiO2 has also been discussed. Similar such degradation studies for ethylamine (EA), aniline (A), diphenylamine (DPA) and naphthylamine (NA) in the presence of ultrasound, TiO2 and rare earths (REs); La, Pr, Nd, Sm and Gd, in aqueous solutions at 20 kHz and 250 W power have been carried out and reported, to examine the combinatorial efficacy of ultrasound in the presence of a photocatalyst and rare earth ions with reactive f-electrons.

  17. Plant Wall Degradative Compounds and Systems

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The present invention relates to cell wall degradative systems, in particular to systems containing enzymes that bind to and/or depolymerize cellulose. These systems...

  18. Degradation of microcystin by gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J.B. [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); Zheng, Z. [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China)], E-mail: zzheng@nju.edu.cn; Yang, G.J. [State Power Environmental Protection Research Institute, Nanjing 210031 (China); Zhao, Y.F. [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China)

    2007-09-21

    The radiolysis of microcystins by gamma irradiation and effects of additives were studied. The degradation value of microcystin-LR was 98.8% at the dose of 8 kGy, while all microcystin-RR could be removed at 5 kGy. Na{sub 2}CO{sub 3} and H{sub 2}O{sub 2} as additives could enhance the degradation efficiency of microcystins. Furthermore, the increase of Na{sub 2}CO{sub 3} would result in the increase of the degradation efficiencies. However, the addition of Triton X-100, NaNO{sub 3} and NaNO{sub 2} inhibited the degradation value of microcystins. The effects of additives were more obvious when the lower doses were selected.

  19. Degradation of microcystin by gamma irradiation

    Science.gov (United States)

    Zhang, J. B.; Zheng, Z.; Yang, G. J.; Zhao, Y. F.

    2007-09-01

    The radiolysis of microcystins by gamma irradiation and effects of additives were studied. The degradation value of microcystin-LR was 98.8% at the dose of 8 kGy, while all microcystin-RR could be removed at 5 kGy. Na 2CO 3 and H 2O 2 as additives could enhance the degradation efficiency of microcystins. Furthermore, the increase of Na 2CO 3 would result in the increase of the degradation efficiencies. However, the addition of Triton X-100, NaNO 3 and NaNO 2 inhibited the degradation value of microcystins. The effects of additives were more obvious when the lower doses were selected.

  20. Degraded core analysis for the PWR

    Energy Technology Data Exchange (ETDEWEB)

    Gittus, J.H.

    1987-10-01

    The paper presents an analysis of the probability and consequences of degraded core accidents for the PWR. The article is based on a paper which was presented by the author to the Sizewell-B public inquiry. Degraded core accidents are examined with respect to:- the initiating events, safety plant failure, and processes with a bearing on containment failure. Accident types and frequencies are discussed, as well as the dispersion of radionuclides. Accident risks, i.e. individual and societal risks in degraded core accidents are assessed from:- the amount of radionuclides released, the weather, the population distribution, and the accident frequencies. Uncertainties in the assessment of degraded core accidents are also summarized. (U.K.).

  1. Degradation of crude oil by marine cyanobacteria

    Digital Repository Service at National Institute of Oceanography (India)

    Raghukumar, C.; Vipparty, V.; David, J.J.; Chandramohan, D.

    The marine cyanobacteria Oscillatoria salina Biswas, Plectonema terebrans Bornet et Flanhault and Aphanocapsa sp. degraded Bombay High crude oil when grown in artificial seawater nutrients as well as in plain natural seawater. Oil removals...

  2. Modelling sulfamethoxazole degradation under different redox conditions

    Science.gov (United States)

    Sanchez-Vila, X.; Rodriguez-Escales, P.

    2015-12-01

    Sulfamethoxazole (SMX) is a low adsorptive, polar, sulfonamide antibiotic, widely present in aquatic environments. Degradation of SMX in subsurface porous media is spatially and temporally variable, depending on various environmental factors such as in situ redox potential, availability of nutrients, local soil characteristics, and temperature. It has been reported that SMX is better degraded under anoxic conditions and by co-metabolism processes. In this work, we first develop a conceptual model of degradation of SMX under different redox conditions (denitrification and iron reducing conditions), and second, we construct a mathematical model that allows reproducing different experiments of SMX degradation reported in the literature. The conceptual model focuses on the molecular behavior and contemplates the formation of different metabolites. The model was validated using the experimental data from Barbieri et al. (2012) and Mohatt et al. (2011). It adequately reproduces the reversible degradation of SMX under the presence of nitrite as an intermediate product of denitrification. In those experiments degradation was mediated by the transient formation of a diazonium cation, which was considered responsible of the substitution of the amine radical by a nitro radical, forming the 4-nitro-SMX. The formation of this metabolite is a reversible process, so that once the concentration of nitrite was back to zero due to further advancement of denitrification, the concentration of SMX was fully recovered. The forward reaction, formation of 4-nitro SMX, was modeled considering a kinetic of second order, whereas the backward reaction, dissociation of 4-nitro-SMX back to the original compound, could be modeled with a first order degradation reaction. Regarding the iron conditions, SMX was degraded due to the oxidation of iron (Fe2+), which was previously oxidized from goethite due to the degradation of a pool of labile organic carbon. As the oxidation of iron occurred on the

  3. [Forest degradation/decline: research and practice].

    Science.gov (United States)

    Zhu, Jiao-Jun; Li, Feng-Qin

    2007-07-01

    As one of the most critical environmental problems in the 21st century, forest degradation has been facing worldwide. There are many definitions about forest degradation, but its common features are the permanent loss of forests, stand structure destructed, forest quality decreased, and forest functions lowered. Forest decline or tree decline in fact is one of the causes of forest degradation, which includes the general reduction of trees in vigor, low level growth of trees in productivity, death of trees, and even, decline of soil fertility. Many researches indicated that deforestation is the permanent loss of forests in area, which is shifted to other land uses. Deforestation is the product of the interactions between environmental, social, economic, cultural, and political forces at work in any given country/region, and thus, more and more attention is focused on the negative socioeconomic and environmental effects after forest degradation, especially on the reduction of forest area induced by deforestation. The effects of any decisions or policies in national and international levels on forest degradation induced by deforestation have been paid attention as well. How to make efforts and strengthen the worldwide cooperation to combat the forest degradation induced by deforestation must be challenged to find appropriate solutions. There are many researches on forest decline, because of its complexity and uncertainties. The major causes of forest decline include: 1) pollution from both industry and agriculture, 2) stress factors, e.g., desiccation, 3) changes in stand dynamics, 4) decline disease of forest or diseases of complex etiology, 5) degradation of productivity and/or soil fertility in pure plantation forests. Forest degradation in China is similar to that all over the world, but with the characteristics in forest components, i.e., 1) secondary forests are the major forest resources, 2) China has the most plantation forests in the world, some of which have

  4. Degradation In Relation To Environmental Conditions

    Science.gov (United States)

    Putters, B.

    One of the parts of the natural attenuation capacity of the soil is its degradation ca- pacity. Usually, the degradation capacity is determined by monitoring contaminant concentrations in the field. However, it is desirable to estimate the degradation ca- pacity of a soil beforehand. For such an estimate, the factors which have the highest influence on the degradation process of a specific contaminant must be known. To find the soil parameters which dominate the degradation behaviour of contaminants in the subsurface, an approach is proposed. The approach consists of 3 steps 1. Derive expected patterns of behaviour under different environmental conditions from litera- ture review. 2. Collect data from published degradation experiments. 3. Explore the dataset by means of statistical techniques. The expected patterns of behaviour are used as guidelines for the exploration of the dataset. Three types of results are derived from dataset exploration: 1. The degree of influence of a variable on the degradation rate is found by application of the analysis- of-variance technique. 2. Factors, summarizing the variables under consideration, can be derived by application of principal components analysis. 3. Relationships can be quantified for the whole dataset or for subsets of the dataset by regression analysis. The approach has been applied to atrazine degradation experiments (see also abstract EGS02-A-01204 for poster presentation). The results will be used as an example and to illustrate problems and solutions during processing. This project is part of a Ph.D. study carried out in the framework of Delft Cluster during the period 1999-2003.

  5. Soil Degradation: Will Humankind Ever Learn?

    OpenAIRE

    Douglas L. Karlen; Charles W. Rice

    2015-01-01

    Soil degradation is a global problem caused by many factors including excessive tillage, inappropriate crop rotations, excessive grazing or crop residue removal, deforestation, mining, construction and urban sprawl. To meet the needs of an expanding global population, it is essential for humankind to recognize and understand that improving soil health by adopting sustainable agricultural and land management practices is the best solution for mitigating and reversing current soil degradation t...

  6. Hydrogen degradation of high strength weldable steels

    OpenAIRE

    J. Ćwiek

    2007-01-01

    Purpose: Purpose of this paper is presentation of hydrogen degradation issue of high strength steels andespecially their welded joints. Establishing of applicable mechanisms of hydrogen-enhanced cracking was theaim of performed research.Design/methodology/approach: High strength quenched and tempered steels grade S690Q were used. Weldedjoints were prepared with typical technology used in shipyards. Susceptibility to hydrogen degradation in seawater under cathodic polarization was evaluated wi...

  7. Degradation and recovery of Caribbean coral reefs

    OpenAIRE

    Paredes, Gustavo Adolfo

    2009-01-01

    Coral reef ecosystems worldwide have been seriously impacted by human activities. The current deteriorated state of coral reef communities is the result of a long history of exploitation. The scientific community has recognized the extent of degradation, its consequences, and how little we have done to avoid further degradation only in the last two decades. Marine reserves are one of the main conservation actions that could help to reduce the impacts of human activities on the ecosystem, part...

  8. Photochemical processes for atrazine degradation: methodological approach.

    Science.gov (United States)

    Héquet, V; Gonzalez, C; Le Cloirec, P

    2001-12-01

    Numerous studies have been carried out on s-triazines, and more specifically on atrazine, with the long-term objective of resolving the problems caused by these herbicides: removing them from drinking water. However, applications have remained too limited. So far, processes based on photochemical degradation have been little implemented. We, therefore, investigated the development of photochemical processes, emphasizing their capacity to degrade triazine by photolytic and photocatalytic mode. The study sought to assess the performance of these ssstems. Experiments ts showed that according to a medium pressure mercury source (UV-Vis irradiation), the photolytic degradation of atrazine was very efficient, with a best atrazine degradation half-life shorter that 5 min. The main degradation pathway was deshalogenation. The photocatalytic degradation of atrazine under irradiation over 290 nm in the presence of titanium dioxide was shown to be efficient too, with a half-life of about 20 min. In this case an experimental design was conducted so as to assess the influence of various parameters: pH, water medium, and amount of catalyst. There has been observational evidence for the efficiency of the processes investigated here and for potential technological developments as regards drinking water treatment.

  9. Soil Degradation: Will Humankind Ever Learn?

    Directory of Open Access Journals (Sweden)

    Douglas L. Karlen

    2015-09-01

    Full Text Available Soil degradation is a global problem caused by many factors including excessive tillage, inappropriate crop rotations, excessive grazing or crop residue removal, deforestation, mining, construction and urban sprawl. To meet the needs of an expanding global population, it is essential for humankind to recognize and understand that improving soil health by adopting sustainable agricultural and land management practices is the best solution for mitigating and reversing current soil degradation trends. This research editorial is intended to provide an overview for this Special Issue of Sustainability that examines the global problem of soil degradation through reviews and recent research studies addressing soil health in Africa, Australia, China, Europe, India, North and South America, and Russia. Two common factors—soil erosion and depletion of soil organic matter (SOM—emerge as consistent indicators of how “the thin layer covering the planet that stands between us and starvation” is being degraded. Soil degradation is not a new problem but failing to acknowledge, mitigate, and remediate the multiple factors leading to it is no longer a viable option for humankind. We optimistically conclude that the most promising strategies to mitigate soil degradation are to select appropriate land uses and improve soil management practices so that SOM is increased, soil biology is enhanced, and all forms of erosion are reduced. Collectively, these actions will enable humankind to “take care of the soil so it can take care of us”.

  10. Hydrocarbon degradation by Antarctic coastal bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Cavanagh, J.E. [University of Tasmania, Hobart (Australia). Antarctic Cooperative Research Centre; CSIRO Div of Marine Research, Hobart (Australia); University of Tasmania, Hobart (Australia). Dept. of Agricultural Science; Nichols, P.D. [University of Tasmania, Hobart (Australia). Antarctic Cooperative Research Centre; CSIRO Div. of Marine Research, Hobart (Australia); Franzmann, P.D. [CSIRO Land and Water, Wembley (Australia); McMeekin, T.A. [University of Tasmania, Hobart (Australia). Antarctic Cooperative Research Centre

    1999-07-01

    Bacterial cultures obtained through selective enrichment of beach sand collected 60 days and one year after treatment of sites in a pilot oil spill trial conducted at Airport Beach, Vestfold Hills, East Antarctica, were examined for the ability to degrade n-alkanes and phenanthrene. The effects of different hydrocarbon mixtures (Special Antarctic Blend [SAB] and BP-Visco), (fish oil [orange roughy]) and inoculation of replicate sites with water from Organic Lake, (previously shown to contain hydrocarbon-degrading bacteria) on the indigenous microbial population, were examined. Of the cultures obtained, those from sites treated with SAB and BP-Visco degraded n-alkanes most consistently and typically to the greatest extent. Two mixed cultures obtained from samples collected at 60 days and two isolates obtained from these cultures extensively degraded phenanthrene. 1-Hydroxy-naphthoic acid formed the major phenanthrene metabolite. Lower levels of salicyclic acid, 1-naphthol, 1,4-naphthaquinone and phenanthrene 9-10 dihydrodiol were detected in extracts of phenanthrene grown cultures. This study shows that under laboratory conditions indigenous Antarctica bacteria can degrade n-alkanes and the more recalcitrant polycyclic aromatic hydrocarbon, phenanthrene. The enrichment of hydrocarbon degrading microorganisms in Antarctic ecosystems exposed to hydrocarbons, is relevant for the long term fate of hydrocarbon spills in this environment. (author)

  11. Mask degradation monitoring with aerial mask inspector

    Science.gov (United States)

    Tseng, Wen-Jui; Fu, Yung-Ying; Lu, Shih-Ping; Jiang, Ming-Sian; Lin, Jeffrey; Wu, Clare; Lifschitz, Sivan; Tam, Aviram

    2013-06-01

    As design rule continues to shrink, microlithography is becoming more challenging and the photomasks need to comply with high scanner laser energy, low CDU, and ever more aggressive RETs. This give rise to numerous challenges in the semiconductor wafer fabrication plants. Some of these challenges being contamination (mainly haze and particles), mask pattern degradation (MoSi oxidation, chrome migration, etc.) and pellicle degradation. Fabs are constantly working to establish an efficient methodology to manage these challenges mainly using mask inspection, wafer inspection, SEM review and CD SEMs. Aerial technology offers a unique opportunity to address the above mask related challenges using one tool. The Applied Materials Aera3TM system has the inherent ability to inspect for defects (haze, particles, etc.), and track mask degradation (e.g. CDU). This paper focuses on haze monitoring, which is still a significant challenge in semiconductor manufacturing, and mask degradation effects that are starting to emerge as the next challenge for high volume semiconductor manufacturers. The paper describes Aerial inspector (Aera3) early haze methodology and mask degradation tracking related to high volume manufacturing. These will be demonstrated on memory products. At the end of the paper we take a brief look on subsequent work currently conducted on the more general issue of photo mask degradation monitoring by means of an Aerial inspector.

  12. Structural elucidation of gemifloxacin mesylate degradation product.

    Science.gov (United States)

    Paim, Clésio Soldateli; Führ, Fernanda; Martins, Magda Targa; Gnoatto, Simone; Bajerski, Lisiane; Garcia, Cássia Virginia; Steppe, Martin; Schapoval, Elfrides Eva Scherman

    2016-03-01

    Gemifloxacin mesylate (GFM), chemically (R,S)-7-[(4Z)-3-(aminomethyl)-4-(methoxyimino)-1-pyrrolidinyl]-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid methanesulfonate, is a synthetic broad-spectrum antibacterial agent. Although many papers have been published in the literature describing the stability of fluorquinolones, little is known about the degradation products of GFM. Forced degradation studies of GFM were performed using radiation (UV-A), acid (1 mol L(-1) HCl) and alkaline conditions (0.2 mol L(-1) NaOH). The main degradation product, formed under alkaline conditions, was isolated using semi-preparative LC and structurally elucidated by nuclear magnetic resonance (proton - (1) H; carbon - (13) C; correlate spectroscopy - COSY; heteronuclear single quantum coherence - HSQC; heteronuclear multiple-bond correlation - HMBC; spectroscopy - infrared, atomic emission and mass spectrometry techniques). The degradation product isolated was characterized as sodium 7-amino-1-pyrrolidinyl-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylate, which was formed by loss of the 3-(aminomethyl)-4-(methoxyimino)-1-pyrrolidinyl ring and formation of the sodium carboxylate. The structural characterization of the degradation product was very important to understand the degradation mechanism of the GFM under alkaline conditions. In addition, the results highlight the importance of appropriate protection against hydrolysis and UV radiation during the drug-development process, storage, handling and quality control.

  13. Microbial PAH-Degradation in Soil: Degradation Pathways and Contributing Factors

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xu-Xiang; CHENG Shu-Pei; ZHU Cheng-Jun; SUN Shi-Lei

    2006-01-01

    Adverse effects on the environment and high persistence in the microbial degradation and environmental fate of polycyclic aromatic hydrocarbons (PAHs) are motivating interest. Many soil microorganisms can degrade PAHs and use various metabolic pathways to do so. However, both the physio-chemical characteristics of compounds as well as the physical, chemical, and biological properties of soils can drastically influence the degradation capacity of naturally occurring microorganisms for field bioremediation. Modern biological techniques have been widely used to promote the efficiency of microbial PAH-degradation and make the biodegradation metabolic pathways more clear. In this review microbial degradation of PAHs in soil is discussed, with emphasis placed on the main degradation pathways and the environmental factors affecting biodegradation.

  14. A thermo-degradable hydrogel with light-tunable degradation and drug release.

    Science.gov (United States)

    Hu, Jingjing; Chen, Yihua; Li, Yunqi; Zhou, Zhengjie; Cheng, Yiyun

    2017-01-01

    The development of thermo-degradable hydrogels is of great importance in drug delivery. However, it still remains a huge challenge to prepare thermo-degradable hydrogels with inherent degradation, reproducible, repeated and tunable dosing. Here, we reported a thermo-degradable hydrogel that is rapidly degraded above 44 °C by a facile chemistry. Besides thermo-degradability, the hydrogel also undergoes rapid photolysis with ultraviolet light. By embedding photothermal nanoparticles or upconversion nanoparticles into the gel, it can release the entrapped cargoes such as dyes, enzymes and anticancer drugs in an on-demand and dose-tunable fashion upon near-infrared light exposure. The smart hydrogel works well both in vitro and in vivo without involving sophisticated syntheses, and is well suited for clinical cancer therapy due to the high transparency and non-invasiveness features of near-infrared light.

  15. Degradation of diclofenac by UV-activated persulfate process: Kinetic studies, degradation pathways and toxicity assessments.

    Science.gov (United States)

    Lu, Xian; Shao, Yisheng; Gao, Naiyun; Chen, Juxiang; Zhang, Yansen; Xiang, Huiming; Guo, Youluo

    2017-03-21

    Diclofenac (DCF) is the frequently detected non-steroidal pharmaceuticals in the aquatic environment. In this study, the degradation of DCF was evaluated by UV-254nm activated persulfate (UV/PS). The degradation of DCF followed the pseudo first-order kinetics pattern. The degradation rate constant (kobs) was accelerated by UV/PS compared to UV alone and PS alone. Increasing the initial PS dosage or solution pH significantly enhanced the degradation efficiency. Presence of various natural water constituents had different effects on DCF degradation, with an enhancement or inhibition in the presence of inorganic anions (HCO3(-) or Cl(-)) and a significant inhibition in the presence of NOM. In addition, preliminary degradation mechanisms and major products were elucidated using LC-MS/MS. Hydroxylation, decarbonylation, ring-opening and cyclation reaction involving the attack of SO4(•)(-) or other substances, were the main degradation mechanism. TOC analyzer and Microtox bioassay were employed to evaluate the mineralization and cytotoxicity of solutions treated by UV/PS at different times, respectively. Limited elimination of TOC (32%) was observed during the mineralization of DCF. More toxic degradation products and their related intermediate species were formed, and the UV/PS process was suitable for removing the toxicity. Of note, longer degradation time may be considered for the final toxicity removal.

  16. Degradation and induction specificity in actinomycetes that degrade p-nitrophenol.

    OpenAIRE

    1993-01-01

    We have isolated two soil bacteria (identified as Arthrobacter aurescens TW17 and Nocardia sp. strain TW2) capable of degrading p-nitrophenol (PNP) and numerous other phenolic compounds. A. aurescens TW17 contains a large plasmid which correlated with the PNP degradation phenotype. Degradation of PNP by A. aurescens TW17 was induced by preexposure to PNP, 4-nitrocatechol, 3-methyl-4-nitrophenol, or m-nitrophenol, whereas PNP degradation by Nocardia sp. strain TW2 was induced by PNP, 4-nitroca...

  17. Abeta-degrading enzymes in Alzheimer's disease.

    Science.gov (United States)

    Miners, James Scott; Baig, Shabnam; Palmer, Jennifer; Palmer, Laura E; Kehoe, Patrick G; Love, Seth

    2008-04-01

    In Alzheimer's disease (AD) Abeta accumulates because of imbalance between the production of Abeta and its removal from the brain. There is increasing evidence that in most sporadic forms of AD, the accumulation of Abeta is partly, if not in some cases solely, because of defects in its removal--mediated through a combination of diffusion along perivascular extracellular matrix, transport across vessel walls into the blood stream and enzymatic degradation. Multiple enzymes within the central nervous system (CNS) are capable of degrading Abeta. Most are produced by neurons or glia, but some are expressed in the cerebral vasculature, where reduced Abeta-degrading activity may contribute to the development of cerebral amyloid angiopathy (CAA). Neprilysin and insulin-degrading enzyme (IDE), which have been most extensively studied, are expressed both neuronally and within the vasculature. The levels of both of these enzymes are reduced in AD although the correlation with enzyme activity is still not entirely clear. Other enzymes shown capable of degrading Abetain vitro or in animal studies include plasmin; endothelin-converting enzymes ECE-1 and -2; matrix metalloproteinases MMP-2, -3 and -9; and angiotensin-converting enzyme (ACE). The levels of plasmin and plasminogen activators (uPA and tPA) and ECE-2 are reported to be reduced in AD. Reductions in neprilysin, IDE and plasmin in AD have been associated with possession of APOEepsilon4. We found no change in the level or activity of MMP-2, -3 or -9 in AD. The level and activity of ACE are increased, the level being directly related to Abeta plaque load. Up-regulation of some Abeta-degrading enzymes may initially compensate for declining activity of others, but as age, genetic factors and diseases such as hypertension and diabetes diminish the effectiveness of other Abeta-clearance pathways, reductions in the activity of particular Abeta-degrading enzymes may become critical, leading to the development of AD and CAA.

  18. Self-degradable Cementitious Sealing Materials

    Energy Technology Data Exchange (ETDEWEB)

    Sugama, T.; Butcher, T., Lance Brothers, Bour, D.

    2010-10-01

    A self-degradable alkali-activated cementitious material consisting of a sodium silicate activator, slag, Class C fly ash, and sodium carboxymethyl cellulose (CMC) additive was formulated as one dry mix component, and we evaluated its potential in laboratory for use as a temporary sealing material for Enhanced Geothermal System (EGS) wells. The self-degradation of alkali-activated cementitious material (AACM) occurred, when AACM heated at temperatures of {ge}200 C came in contact with water. We interpreted the mechanism of this water-initiated self-degradation as resulting from the in-situ exothermic reactions between the reactants yielded from the dissolution of the non-reacted or partially reacted sodium silicate activator and the thermal degradation of the CMC. The magnitude of self-degradation depended on the CMC content; its effective content in promoting degradation was {ge}0.7%. In contrast, no self-degradation was observed from CMC-modified Class G well cement. For 200 C-autoclaved AACMs without CMC, followed by heating at temperatures up to 300 C, they had a compressive strength ranging from 5982 to 4945 psi, which is {approx}3.5-fold higher than that of the commercial Class G well cement; the initial- and final-setting times of this AACM slurry at 85 C were {approx}60 and {approx}90 min. Two well-formed crystalline hydration phases, 1.1 nm tobermorite and calcium silicate hydrate (I), were responsible for developing this excellent high compressive strength. Although CMC is an attractive, as a degradation-promoting additive, its addition to both the AACM and the Class G well cement altered some properties of original cementitious materials; among those were an extending their setting times, an increasing their porosity, and lowering their compressive strength. Nevertheless, a 0.7% CMC-modified AACM as self-degradable cementitious material displayed the following properties before its breakdown by water; {approx}120 min initial- and {approx}180 min final

  19. Microbial Degradation of Aniline by Bacterial Consortium

    Institute of Scientific and Technical Information of China (English)

    JIAN-LONG WANG; ZE-YU MAO; WEI-ZHONG WU

    2003-01-01

    Objective To investigate the characteristics of microbial degradation of aniline by a stable bacterial consortium. Methods The bacterial consortium was isolated from activated sludge treating chemical wastewater using aniline as the sole source of carbon and nitrogen by enrichment and isolation technique. The biomass was measured as optical density (OD) at 510 nm using a spectrophotometer. Aniline concentrations were determined by spectrophotometer. The intermediates of aniline degradation were identified by GC/MS method. Results The bacterial consortium could grow at a range of aniline concentrations between 50 and 500 mg/L. The optimal pH and temperature for aniline degradation were determined to be 7.0 and 30, respectively. The presence of NH4NO3 as an additional nitrogen source (100-500 mg/L) had no adverse effect on bacterial growth and aniline degradation. The presence of heavy metal ions, such as Co2+, Zn2+, Ni2+, Mn2+ and Cu2+ had an inhibitory effect on aniline degradation. Conclusions The isolated bacterial consortium candegrade aniline up to 500 mg/L effectively and tolerate some heavy metal ions that commonly exist in chemical wastewater. It has a potential to be applied in the practical treatment of aniline-containingwastewater.

  20. Photocatalytic degradation of molinate in aqueous solutions.

    Science.gov (United States)

    Bizani, E; Lambropoulou, D; Fytianos, K; Poulios, I

    2014-11-01

    In this study, the degradation of molinate through heterogeneous photocatalysis, using two different types of the semiconductor TiO2 as photocatalyst, as well as through homogeneous treatment, applying the photo-Fenton reaction, has been investigated. As far as heterogeneous photocatalysis is concerned, the degradation of the pesticide follows apparent first-order kinetics, while the type of the catalyst and the pH value of the solution affect the degradation rate. The effect of the addition of electron scavengers (H2O2 and K2S2O8) was also studied. In the case of photo-Fenton-assisted system, the degradation also follows pseudo-first-order kinetics. Parameters such as iron's and electron scavenger's concentration and inorganic ions strongly affect the degradation rate. The extent of pesticide mineralization was investigated using dissolved organic carbon (DOC) measurements. The toxicity of the treated solution was evaluated using the Microtox test based on the luminescent bacteria Vibrio fischeri. The detoxification and mineralization efficiency was found to be dependent on the system studied, and although it did not follow the rate of pesticide disappearance, it took place in considerable extent. The study of the photodegradation treatment was completed by the determination of the intermediate by-products formed during the process, which was carried out using LC-MS/MS technique and led to similar compounds with both processes.

  1. Degradable polymeric materials for osteosynthesis: Tutorial

    Directory of Open Access Journals (Sweden)

    D Eglin

    2008-12-01

    Full Text Available This report summarizes the state of the art and recent developments and advances in the use of degradable polymers devices for osteosynthesis. The current generation of biodegradable polymeric implants for bone repair utilising designs copied from metal implants, originates from the concept that devices should be supportive and as “inert” substitute to bone tissue. Today degradable polymeric devices for osteosynthesis are successful in low or mild load bearing applications. However, the lack of carefully controlled randomized prospective trials that document their efficacy in treating a particular fracture pattern is still an issue. Then, the choice between degradable and non-degradable devices must be carefully weighed and depends on many factors such as the patient age and condition, the type of fracture, the risk of infection, etc. The improvement of the biodegradable devices mechanical properties and their degradation behaviour will have to be achieved to broaden their use. The next generation of biodegradable implants will probably see the implementation of the recent gained knowledge in cell-material interactions and cells therapy, with a better control of the spatial and temporal interfaces between the material and the surrounding bone tissue.

  2. Degradation of textile dyes by cyanobacteria

    Directory of Open Access Journals (Sweden)

    Priscila Maria Dellamatrice

    Full Text Available Abstract Dyes are recalcitrant compounds that resist conventional biological treatments. The degradation of three textile dyes (Indigo, RBBR and Sulphur Black, and the dye-containing liquid effluent and solid waste from the Municipal Treatment Station, Americana, São Paulo, Brazil, by the cyanobacteria Anabaena flos-aquae UTCC64, Phormidium autumnale UTEX1580 and Synechococcus sp. PCC7942 was evaluated. The dye degradation efficiency of the cyanobacteria was compared with anaerobic and anaerobic-aerobic systems in terms of discolouration and toxicity evaluations. The discoloration was evaluated by absorption spectroscopy. Toxicity was measured using the organisms Hydra attenuata, the alga Selenastrum capricornutum and lettuce seeds. The three cyanobacteria showed the potential to remediate textile effluent by removing the colour and reducing the toxicity. However, the growth of cyanobacteria on sludge was slow and discoloration was not efficient. The cyanobacteria P. autumnale UTEX1580 was the only strain that completely degraded the indigo dye. An evaluation of the mutagenicity potential was performed by use of the micronucleus assay using Allium sp. No mutagenicity was observed after the treatment. Two metabolites were produced during the degradation, anthranilic acid and isatin, but toxicity did not increase after the treatment. The cyanobacteria showed the ability to degrade the dyes present in a textile effluent; therefore, they can be used in a tertiary treatment of effluents with recalcitrant compounds.

  3. Inhibitors and pathways of hepatocytic protein degradation.

    Science.gov (United States)

    Seglen, P O; Gordon, P B; Grinde, B; Solheim, A; Kovács, A L; Poli, A

    1981-01-01

    On the basis of experiments using amino acids and various inhibitors (lysosomotropic amines, leupeptin, chymostatin, vanadate, vinblastine, anoxia, methylaminopurines), five different modes of endogenous protein degradation in isolated rat hepatocytes can be distinguished. The two non-lysosomal (amine-resistant) mechanisms preferentially degrade relatively labile (short-lived) proteins: one of these mechanisms is energy-dependent and chymostatin-sensitive, the other is not. Of the three lysosomal (amine-sensitive) mechanisms, one--quantitatively minor--is amino acid-resistant and preferentially degrades labile proteins. The two amino acid-sensitive mechanisms each seen account for about one-half of the degradation of relatively stable (long-lived) proteins; one of them is suppressed by leucine and apparently corresponds to the formation of electron microscopically visible autophagosomes; the other may represent a different type of autophagy, inhibited by asparagine and glutamine. A new class of inhibitors, the purine derivatives (methylated 6-aminopurines, and 6-mercaptopurines) appear to specifically suppress autophagic/lysosomal protein degradation, and may help to further elucidate the mechanisms of autophagy.

  4. Accelerated degradation studies of encapsulation polymers

    Science.gov (United States)

    Weiss, Karl-Anders; Huelsmann, Jan Philip; Kaltenbach, Thomas; Philipp, Daniel; Schuhmacher, Tanja; Wirth, Jochen; Koehl, Michael

    2008-08-01

    The estimation of PV-modules lifetime facilitates the further development and helps to lower risks for producers and investors. One base for this extensive testing and simulation work is the knowledge of the chemical degradation processes and their kinetics, as well as of the permeation of water and oxygen into the module, especially of the encapsulant. Besides ethylen-vinylacetate copolymer (EVA), which is the dominant material for encapsulation, new materials become available and need the assessment of their properties and the durability impact. Accelerated durability tests were performed on different EVA materials. The paper reports on several measurement methods for analysis of the polymers that were used, FT-IR with attenuated total reflection (ATR), and Raman microscopy, e.g. It is very important to identify degradation products and intermediates in order to identify the leading degradation processes and their kinetics as well as potential interactions between different processes. Another important factor for the degradation of the PV-modules and the concerned polymers in particular is the permeation of reactive substances, especially of water vapor, into and inside the modules. The paper shows results of permeation measurements of the new materials, as well as FEM-based numerical simulations of the humidity diffusion within a PV-module what is an important step towards the calculation of the chemical degradation using numerical simulation tools in the future.

  5. Quantitative accelerated degradation testing: Practical approaches

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadian, S. Hossein, E-mail: seyed-h.mohammadian.1@ulaval.c [Centre Interuniversitaire de Recherche sur les Reseaux d' Entreprise, la Logistique et le Transport (CIRRELT), Departement de Genie Mecanique, Pavillon Adrien-Pouliot, Universite Laval, Quebec, G1V 0A6 (Canada) and Centre Interdisciplinaire de Recherche en Readaptation et en Integration Sociale (CIRRIS), Institut de Readaptation en Deficience Physique de Quebec, 525 Boul. Hamel, Quebec, G1M 2S8 (Canada); Ait-Kadi, Daoud, E-mail: Daoud.Aitkadi@gmc.ulaval.c [Centre Interuniversitaire de Recherche sur les Reseaux d' Entreprise, la Logistique et le Transport (CIRRELT), Departement de Genie Mecanique, Pavillon Adrien-Pouliot, Universite Laval, Quebec, G1V 0A6 (Canada); Centre Interdisciplinaire de Recherche en Readaptation et en Integration Sociale (CIRRIS), Institut de Readaptation en Deficience Physique de Quebec, 525 Boul. Hamel, Quebec, G1M 2S8 (Canada); Routhier, Francois, E-mail: Francois.Routhier@rea.ulaval.c [Centre Interdisciplinaire de Recherche en Readaptation et en Integration Sociale (CIRRIS), Institut de Readaptation en Deficience Physique de Quebec, 525 Boul. Hamel, Quebec, G1M 2S8 (Canada)

    2010-02-15

    The concept of accelerated testing by tracking degradation of samples over test time needs to be developed for reliability estimation. This paper aims at proposing practical approaches to conduct accelerated degradation testing on new and available used samples. For this purpose, product failure is related to a suitable physical property. Then, its failure time is defined as the expected time in which its property reaches the critical level. Degradation model of field samples returned from service due to a degrading failure mode has been estimated based on the least square method, and available gap between manufacturer criterion and user's claim (to report a failure) has also been discussed. For a product under some stresses, a general formula has been proposed by the superposition principle in order to estimate its degradation for independent and dependent failure modes. If used samples are available, and acceleration factor of the related test is unknown, partial aging method has been presented to considerably shorten the test time.

  6. Degradation behavior of poly(glycerol sebacate).

    Science.gov (United States)

    Pomerantseva, Irina; Krebs, Nicholas; Hart, Alison; Neville, Craig M; Huang, Albert Y; Sundback, Cathryn A

    2009-12-15

    Poly(glycerol sebacate) (PGS), a promising scaffold material for soft tissue engineering applications, is a soft, tough elastomer with excellent biocompatibility. However, the rapid in vivo degradation rate of PGS limits its use as a scaffold material. To determine the impact of crosslink density on degradation rate, a family of PGS materials was synthesized by incrementally increasing the curing time from 42 to 144 h, at 120 degrees C and 10 mTorr vacuum. As expected, PGS became a stiffer, tougher, and stronger elastomer with increasing curing time. PGS disks were subcutaneously implanted into rats and periodically harvested; only mild tissue responses were observed and the biocompatibility remained excellent. Regardless of crosslink density, surface erosion degradation was observed. The sample dimensions linearly decreased with implantation time, and the mass loss rates were constant after 1-week implantation. As surface erosion degradation frequently correlates with enzymatic digestion, parallel in vitro digestion studies were conducted in lipase solutions which hydrolyze ester bonds. Enzymatic digestion played a significant role in degrading PGS, and the mass loss rates were not a function of curing time. Alternative chemistry approaches will be required to decrease the enzymatic hydrolysis rate of the ester bonds in PGS polymers.

  7. Anaerobic microbial degradation of organochlorine insecticides Aldrin

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, T.C.; Yen, J.H.; Wang, Y.S. [National Taiwan Univ. (Taiwan)

    2004-09-15

    Aldrin (1,2,3,4,10,10-hexachloro-1,4,4a,5,8,8a-hexahydro-1,4-endo-exo-5,8-dimethanonnaphthalene), a cyclodiene organochlorine insecticide, was banned by nations and classified as B2 carcinogen by United States Environmental Protection Agency (EPA). Because of its chemical stability and lipophilicity, aldrin is regarded as a persistent and recalcitrant compound. Aldrin is easily adsorbed to soil and sediment after spreading to the environments, furthermore, it may be accumulated in animal's tissue or milk and then cause adverse effects by food-chain. The dissipation process of aldrin in environments has continuously been paid much attention by researchers. In general, the dissipation of aldrin has been thought as relating to three mechanisms: photo-degradation, chemical hydrolysis, and microbial degradation. And it has been well known that microbial degradation is the most important agent for breakdown of organochlorine pesticides. There has been shown that aldrin could be transformed to its metabolites, such as dieldrin or photo-dieldrin, by microorganisms under aerobic conditions, however, limited information has been shown under anaerobic conditions. For this reason, the degradation potential of aldrin by anaerobic microorganisms obtained from indigenous river sediment was evaluated, and the effect of environmental factors such as temperatures and nutrients on the aldrin degradation was also investigated in this study.

  8. [Effects of nitrogen and phosphorus fertilizer on atrazine degradation and detoxification by degrading strain HB-5].

    Science.gov (United States)

    Su, Jun; Zhu, Lu-Sheng; Li, Xu-Hua; Wang, Jun; Xie, Hui; Wang, Jin-Hua; Wang, Qi; Jia, Wen-Tao

    2010-10-01

    An atrazine-degrading strain HB-5 was used as a bacteria for biodegradation. Treatments of soil with nitrogen single, phosphate single and nitrogen phosphate together with HB-5 were carried out for degradation and eco-toxicity test; then, relationship between atrazine degradation rate and soil available nitrogen, available phosphorus were discussed. Atrazine residues were determined by HPLC; available nitrogen was determined with alkaline hydrolysis diffusion method; available phosphorus was determined with 0.5 mol/L-NaHCO3 extraction and molybdenum stibium anti-color method, and toxicity test was carried out with micronucleus test of Vicia faba root tip cells. The results showed that: After separately or together application, nitrogenous and phosphorous fertilizers could significantly accelerate atrazine degradation than soil with HB-5 only. On day 5, the order of atrazine degradation was ANP > AP > AN > A; 7 days later, no statistically significant differences were found between treatments. The available nitrogen and phosphorus level in soil reduced as the degradation rate increased in the soil. The soil of eco-toxicity test results indicated that the eco-toxicity significantly reduced with the degradation of atrazine by HB-5, and the eco-toxicity on treatments of soil with fertilizer were all below the treatments without fertilizer. On day 5, the order of eco-toxicity was ANP atrazine degradation in soil but also could reduce the soil eco-toxicity effects that atrazine caused. All these results could be keystone of atrazine pollution remediation in contaminated soil in the future.

  9. Hydrocarbon degradation, plant colonization and gene expression of alkane degradation genes by endophytic Enterobacter ludwigii strains

    Energy Technology Data Exchange (ETDEWEB)

    Yousaf, Sohail [AIT Austrian Institute of Technology GmbH, Bioresources Unit, A-2444 Seibersdorf (Austria); Afzal, Muhammad [AIT Austrian Institute of Technology GmbH, Bioresources Unit, A-2444 Seibersdorf (Austria); National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad (Pakistan); Reichenauer, Thomas G. [AIT Austrian Institute of Technology GmbH, Environmental Resources and Technologies Unit, A-2444 Seibersdorf (Austria); Brady, Carrie L. [Forestry and Agricultural Biotechnology Institute, Department of Microbiology and Plant Pathology, University of Pretoria, Pretoria (South Africa); Sessitsch, Angela, E-mail: angela.sessitsch@ait.ac.at [AIT Austrian Institute of Technology GmbH, Bioresources Unit, A-2444 Seibersdorf (Austria)

    2011-10-15

    The genus Enterobacter comprises a range of beneficial plant-associated bacteria showing plant growth promotion. Enterobacter ludwigii belongs to the Enterobacter cloacae complex and has been reported to include human pathogens but also plant-associated strains with plant beneficial capacities. To assess the role of Enterobacter endophytes in hydrocarbon degradation, plant colonization, abundance and expression of CYP153 genes in different plant compartments, three plant species (Italian ryegrass, birdsfoot trefoil and alfalfa) were grown in sterile soil spiked with 1% diesel and inoculated with three endophytic E. ludwigii strains. Results showed that all strains were capable of hydrocarbon degradation and efficiently colonized the rhizosphere and plant interior. Two strains, ISI10-3 and BRI10-9, showed highest degradation rates of diesel fuel up to 68% and performed best in combination with Italian ryegrass and alfalfa. All strains expressed the CYP153 gene in all plant compartments, indicating an active role in degradation of diesel in association with plants. - Highlights: > E. ludwigii strains efficiently colonized plants in a non-sterile soil environment. > E. ludwigii strains efficiently expressed alkane degradation genes in plants. > E. ludwigii efficiently degraded alkane contaminations and promoted plant growth. > E. ludwigii interacted more effectively with Italian ryegrass than with other plants. > Degradation activity varied with plant and microbial genotype as well as with time. - Enterobacter ludwigii strains belonging to the E. cloacae complex are able to efficiently degrade alkanes when associated with plants and to promote plant growth.

  10. Optimized cultivation of highly-efficient degradation bacterial strains and their degradation ability towards pyrene

    Institute of Scientific and Technical Information of China (English)

    HOU Shuyu; ZHANG Qingmin; DUO Miao; ZHANG Yang; SUN Hongwen

    2007-01-01

    Two bacterial strains,Pyl and Py4,have been tamed and isolated through long cultivation with polycyclic aromatic hydrocarbon-pyrene as the single carbon source.It has been proven that they are both highly-efficient pyrene degrading bacteria and both Bacillus sp..The pyrene degradation ability of separated Pyl,Py4 and the consortium of equal Pyl and Py4 was studied in this project.It is shown that pyrene degradation rates were 88% in 10hr by Py1,84% in 14hr by Py4,and 88% in 8hr by the consortium.It was also determined that the best degradation temperatures were 37℃ and pH 7.0 respectively.The influence of different nutrient substrates added in the degradation experiments was also studied.It was shown that sodium salicylate,sodium acetate and yeast exuact had obvious simulative effect,but glucose had no obvious effect.

  11. Degradation and induction specificity in actinomycetes that degrade p-nitrophenol

    Energy Technology Data Exchange (ETDEWEB)

    Hanne, L.F.; Kirk, L.L.; Appel, S.M.; Narayan, A.D.; Bains, K.K. (California State Univ., Chico, CA (United States))

    1993-10-01

    We have isolated two soil bacteria (identified as Arthrobacter aurescens TW17 and Nocardia sp. strain TW2) capable of degrading p-nitrophenol (PNP) and numerous other phenolic compounds. A. aurescens TW17 contains a large plasmid which correlated with the PNP degradation phenotype. Degradation of PNP by A. aurescens TW 17 was induced by preexposure to PNP, 4-nitrocatechol, 3-methyl-4-nitrophenol, or m-nitrophenol, whereas PNP degradation by Nocardia sp. strain TW2 was induced by PNP, 4-nitrocatechol, phenol, p-cresol, or m-nitrophenol. A. aurescens TW17 initially degraded PNP to hydroquinone and nitrite. Nocardia sp. strain TW2 initially converted PNP to hydroquinone or 4-nitrocatechol, depending upon the inducing compound.

  12. Degradation of endocrine disrupting chemicals by genetic transformants with two lignin degrading enzymes in Phlebia tremellosa.

    Science.gov (United States)

    Kum, Hyunwoo; Lee, Sungsuk; Ryu, Sunhwa; Choi, Hyoung T

    2011-10-01

    A white rot fungus Phlebia tremellosa produced lignin degrading enzymes, which showed degrading activity against various recalcitrant compounds. However, manganese peroxidase (MnP) activity, one of lignin degrading enzymes, was very low in this fungus under various culture conditions. An expression vector that carried both the laccase and MnP genes was constructed using laccase genomic DNA of P. tremellosa and MnP cDNA from Polyporus brumalis. P. tremellosa was genetically transformed using the expression vector to obtain fungal transformants showing increased laccase and MnP activity. Many transformants showed highly increased laccase and MnP activity at the same time in liquid medium, and three of them were used to degrade endocrine disrupting chemicals. The transformant not only degraded bisphenol A and nonylphenol more rapidly but also removed the estrogenic activities of the chemicals faster than the wild type strain.

  13. Emdogain stimulates matrix degradation by osteoblasts.

    Science.gov (United States)

    Goda, S; Inoue, H; Kaneshita, Y; Nagano, Y; Ikeo, T; Ikeo, Y T; Iida, J; Domae, N

    2008-08-01

    Emdogain has been used clinically for periodontal regeneration, although the underlying molecular mechanisms are not clear at present. In this study, we hypothesized that Emdogain stimulated degradation of type I collagen via osteoblasts. We showed that Emdogain enhanced cell-mediated degradation of type I collagen in an MMP-dependent manner. Although MG-63 cells spontaneously produced a zymogen form of MMP-1, treatment with Emdogain significantly induced the generation of the active form of this enzyme. We demonstrated that MMP-3 was produced from MG63 cells in response to Emdogain in a MEK1/2-dependent manner. Concomitantly, blocking of MEK1/2 activation by U0126 significantly inhibited the generation of the active form of MMP-1 without affecting the total production of this collagenase. These results suggest that Emdogain facilitates tissue regeneration through the activation of the collagenase, MMP-1, that degrades matrix proteins in bone tissue microenvironments.

  14. Anaerobic lipid degradation through acidification and methanization.

    Science.gov (United States)

    Kim, Ijung; Kim, Sang-Hyoun; Shin, Hang-Sik; Jung, Jin-Young

    2010-01-01

    In biological wastewater treatment high lipid concentration is known to inhibit microorganisms and cause active biomass flotation. To reduce lipid inhibition, a two-phase anaerobic system, consisting of an anaerobic sequencing batch reactor (ASBR) and an upflow anaerobic sludge blanket (UASB) reactor, was applied to synthetic dairy wastewater. During 153 days of operation, the two-phase system showed stable performance in lipid degradation. In the ASBR, a 13% lipid removal efficiency and 10% double bond removal efficiency were maintained. In the UASB, the chemical oxygen demand (COD), lipid and volatile fatty acid (VFA) removal efficiencies were more than 80%, 70% and 95%, respectively, up to organic loading rate 6.5 g COD/L/day. There were no operational problems such as serious scum formation or sludge washout. Protein degradation occurred prior to degradation during acidogenesis.

  15. Insulation Degradation Diagnostic Technology to XLPE Cable

    Science.gov (United States)

    Uchida, Katsumi; Okamoto, Tatsuki

    XLPE power cables have been in use for long time now and some of them are approaching 30 years of their designed lifetime. However, under the present severe economic situation, it is necessary to use the existing apparatus as long as possible. So, degradation diagnostic methods with high reliability are needed earnestly. This paper explains the insulation degradation mechanism of XLPE power cables and the newest diagnostic methods on each voltage class. In 3.3-77kV classes, fairly high extents of the cable accidents depend on the water-tree degradation. For 3.3-6.6kV class cables, on-line diagnostic methods with high reliability to detect bridged water-trees have been developed and put in practical use. And, for 22-77kV classes, two promising off-line diagnostic methods to detect un-bridged water-trees have begun to carry out in on-site tests.

  16. Polymer scaffold degradation control via chemical control

    Science.gov (United States)

    Hedberg-Dirk, Elizabeth L.; Dirk, Shawn; Cicotte, Kirsten

    2016-01-05

    A variety of polymers and copolymers suitable for use as biologically compatible constructs and, as a non-limiting specific example, in the formation of degradable tissue scaffolds as well methods for synthesizing these polymers and copolymers are described. The polymers and copolymers have degradation rates that are substantially faster than those of previously described polymers suitable for the same uses. Copolymers having a synthesis route which enables one to fine tune the degradation rate by selecting the specific stoichiometry of the monomers in the resulting copolymer are also described. The disclosure also provides a novel synthesis route for maleoyl chloride which yields monomers suitable for use in the copolymer synthesis methods described herein.

  17. Degradation of Silicone Encapsulants in CPV Optics

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Can; Miller, David C.; Tappan, Ian A.; Dauskardt, Reinhold H.

    2016-11-21

    High efficiency multijunction solar cells in terrestrial concentrator photovoltaic (CPV) modules are becoming an increasingly cost effective and viable option in utility scale power generation. As with other utility scale photovoltaics, CPV modules need to guarantee operational lifetimes of at least 25 years. The reliability of optical elements in CPV modules poses a unique materials challenge due to the increased UV irradiance and enhanced temperature cycling associated with concentrated solar flux. The polymeric and thin film materials used in the optical elements are especially susceptible to UV damage, diurnal temperature cycling and active chemical species from the environment. We used fracture mechanics approaches to study the degradation modes including: the adhesion between the encapsulant and the cell or secondary optical element; and the cohesion of the encapsulant itself. Understanding the underlying mechanisms of materials degradation under elevated stress conditions is critical for commercialization of CPV technology and can offer unique insights into degradation modes in similar encapsulants used in other photovoltaic modules.

  18. Hot carrier injection degradation under dynamic stress

    Institute of Scientific and Technical Information of China (English)

    Ma Xiao-Hua; Cao Yan-Rong; Hao Yue; Zhang Yue

    2011-01-01

    In this paper, we have studied hot carrier injection (HCI) under alternant stress. Under different stress modes, different degradations are obtained from the experiment results. The different alternate stresses can reduce or enhance the HC effect, which mainly depends on the latter condition of the stress cycle. In the stress mode A (DC stress with electron injection), the degradation keeps increasing. In the stress modes B (DC stress and then stress with the smallest gate injection) and C (DC stress and then stress with hole injection under Vg=0V and Vd = 1.8 V), recovery appears in the second stress period. And in the stress mode D (DC stress and then stress with hole injection under Vg = -1.8 V and Vd = 1.8 V), as the traps filled in by holes can be smaller or greater than the generated interface states, the continued degradation or recovery in different stress periods can be obtained.

  19. Degradation of 5-hydroxymethylfurfural during yeast fermentation.

    Science.gov (United States)

    Akıllıoglu, Halise Gül; Mogol, Burçe Ataç; Gökmen, Vural

    2011-12-01

    5-Hydroxymethyl furfural (HMF) may occur in malt in high quantities depending on roasting conditions. However, the HMF content of different types of beers is relatively low, indicating its potential for degradation during fermentation. This study investigates the degradation kinetics of HMF in wort during fermentation by Saccharomyces cerevisiae. The results indicated that HMF decreased exponentially as fermentation progressed. The first-order degradation rate of HMF was 0.693 × 10(-2) and 1.397 × 10(-2)min(-1) for wort and sweet wort, respectively, indicating that sugar enhances the activity of yeasts. In wort, HMF was converted into hydroxymethyl furfuryl alcohol by yeasts with a high yield (79-84% conversion). Glucose and fructose were utilised more rapidly by the yeasts in dark roasted malt than in pale malt (pfermentation medium increases this activity.

  20. Degradation of anthraquinone dyes by ozone

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The decolorization of three kinds of anthraquinone dyes by ozone was investigated and the residues in the degradation solution were analyzed. The results indicate that the decolorizing effects are obvious with the decolorization efficiency of dyes all above 96% in 40 min. The pH value and TOC concentration decline while the conductivity increases with the lapse of reaction time.The complicated dye molecules are decomposed to simple compounds with -SO3H, -Cl in the dye molecules transformed into SO4 2-, Cl-, and nitrogen partially degrades into NO3- according to the bases of different groups. The organic acids are found in the degradation solutions and dyes with larger relative molecular mass are decomposed into substances with larger relative molecular mass.

  1. Oxidation and degradation of polypropylene transvaginal mesh.

    Science.gov (United States)

    Talley, Anne D; Rogers, Bridget R; Iakovlev, Vladimir; Dunn, Russell F; Guelcher, Scott A

    2017-04-01

    Polypropylene (PP) transvaginal mesh (TVM) repair for stress urinary incontinence (SUI) has shown promising short-term objective cure rates. However, life-altering complications have been associated with the placement of PP mesh for SUI repair. PP degradation as a result of the foreign body reaction (FBR) has been proposed as a contributing factor to mesh complications. We hypothesized that PP oxidizes under in vitro conditions simulating the FBR, resulting in degradation of the PP. Three PP mid-urethral slings from two commercial manufacturers were evaluated. Test specimens (n = 6) were incubated in oxidative medium for up to 5 weeks. Oxidation was assessed by Fourier Transform Infrared Spectroscopy (FTIR), and degradation was evaluated by scanning electron microscopy (SEM). FTIR spectra of the slings revealed evidence of carbonyl and hydroxyl peaks after 5 weeks of incubation time, providing evidence of oxidation of PP. SEM images at 5 weeks showed evidence of surface degradation, including pitting and flaking. Thus, oxidation and degradation of PP pelvic mesh were evidenced by chemical and physical changes under simulated in vivo conditions. To assess changes in PP surface chemistry in vivo, fibers were recovered from PP mesh explanted from a single patient without formalin fixation, untreated (n = 5) or scraped (n = 5) to remove tissue, and analyzed by X-ray photoelectron spectroscopy. Mechanical scraping removed adherent tissue, revealing an underlying layer of oxidized PP. These findings underscore the need for further research into the relative contribution of oxidative degradation to complications associated with PP-based TVM devices in larger cohorts of patients.

  2. Volatile hydrocarbons inhibit methanogenic crude oil degradation

    Directory of Open Access Journals (Sweden)

    Angela eSherry

    2014-04-01

    Full Text Available Methanogenic degradation of crude oil in subsurface sediments occurs slowly, but without the need for exogenous electron acceptors, is sustained for long periods and has enormous economic and environmental consequences. Here we show that volatile hydrocarbons are inhibitory to methanogenic oil biodegradation by comparing degradation of an artificially weathered crude oil with volatile hydrocarbons removed, with the same oil that was not weathered. Volatile hydrocarbons (nC5-nC10, methylcyclohexane, benzene, toluene and xylenes were quantified in the headspace of microcosms. Aliphatic (n-alkanes nC12-nC34 and aromatic hydrocarbons (4-methylbiphenyl, 3-methylbiphenyl, 2-methylnaphthalene, 1-methylnaphthalene were quantified in the total hydrocarbon fraction extracted from the microcosms. 16S rRNA genes from key microorganisms known to play an important role in methanogenic alkane degradation (Smithella and Methanomicrobiales were quantified by quantitative PCR. Methane production from degradation of weathered oil in microcosms was rapid (1.1 ± 0.1 µmol CH4/g sediment/day with stoichiometric yields consistent with degradation of heavier n-alkanes (nC12-nC34. For non-weathered oil, degradation rates in microcosms were significantly lower (0.4 ± 0.3 µmol CH4/g sediment/day. This indicated that volatile hydrocarbons present in the non-weathered oil inhibit, but do not completely halt, methanogenic alkane biodegradation. These findings are significant with respect to rates of biodegradation of crude oils with abundant volatile hydrocarbons in anoxic, sulphate-depleted subsurface environments, such as contaminated marine sediments which have been entrained below the sulfate-reduction zone, as well as crude oil biodegradation in petroleum reservoirs and contaminated aquifers.

  3. Synchrotron Investigations of SOFC Cathode Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Idzerda, Yves

    2013-09-30

    The atomic variations occurring in cathode/electrolyte interface regions of La{sub 1-x}Sr{sub x}Co{sub y}Fe{sub 1-y}O{sub 3-δ} (LSCF) cathodes and other SOFC related materials have been investigated and characterized using soft X-ray Absorption Spectroscopy (XAS) and diffuse soft X-ray Resonant Scattering (XRS). X-ray Absorption Spectroscopy in the soft X-ray region (soft XAS) is shown to be a sensitive technique to quantify the disruption that occurs and can be used to suggest a concrete mechanism for the degradation. For LSC, LSF, and LSCF films, a significant degradation mechanism is shown to be Sr out-diffusion. By using the XAS spectra of hexavalent Cr in SrCrO4 and trivalent Cr in Cr2O3, the driving factor for Sr segregation was identified to be the oxygen vacancy concentration at the anode and cathode side of of symmetric LSCF/GDC/LSCF heterostructures. This is direct evidence of vacancy induced cation diffusion and is shown to be a significant indicator of cathode/electrolyte interfacial degradation. X-ray absorption spectroscopy is used to identify the occupation of the A-sites and B-sites for LSC, LSF, and LSCF cathodes doped with other transition metals, including doping induced migration of Sr to the anti-site for Sr, a significant cathode degradation indicator. By using spatially resolved valence mapping of Co, a complete picture of the surface electrochemistry can be determined. This is especially important in identifying degradation phenomena where the degradation is spatially localized to the extremities of the electrochemistry and not the average. For samples that have electrochemical parameters that are measured to be spatially uniform, the Co valence modifications were correlated to the effects of current density, overpotential, and humidity.

  4. Radiation-induced degradation of galactomannan polysaccharides

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Murat [Hacettepe University, Department of Chemistry, Beytepe, 06532 Ankara (Turkey)], E-mail: msen@hacettepe.edu.tr; Yolacan, Burcu; Gueven, Olgun [Hacettepe University, Department of Chemistry, Beytepe, 06532 Ankara (Turkey)

    2007-12-15

    In this study, guar gum, tara gum and locust bean gum were irradiated in a gamma cell in the solid state. The change in their molecular weights were determined by size exclusion chromatography analysis and the change in their viscosity values with change of temperature and irradiation dose were determined. Chain scission yield, G(s), and degradation rate values were calculated. The calculated G(s) values is 1.09 {+-} 0.16, 1.07 {+-} 0.06, 0.85 {+-} 0.10 for GG, TG and LBG, respectively. The effect of mannose-galactose ratio and initial molecular weight of these gums on the degradation behavior were discussed.

  5. IMPORTANT DEGRADATIONS IN POLYETHYLENE TERAPHTALATE EXTRUSION PROCESS

    Directory of Open Access Journals (Sweden)

    Şule ALTUN

    2003-01-01

    Full Text Available Polyethylene terephthalate (PET is one of the most used thermo-plastic polymers. The total consumption of PET has been about 30 million tons in the year 2000. Polyester fibers constitute about 60 % of total synthetic fibers consumption. During extrusion, PET polymer is faced to thermal, thermo-oxidative and hydrolytic degradation, which result in severe reduction in its molecular weight, thereby adversely affecting its subsequent melt processability. Therefore, it is essential to understand degradation processes of PET during melt extrusion.

  6. 倾斜角对周向重叠三分螺旋折流板换热器性能的影响%Impacts of incline angle on performances of circumferential overlap trisection helical baffle heat exchangers

    Institute of Scientific and Technical Information of China (English)

    董聪; 陈亚平; 吴嘉峰

    2016-01-01

    对倾斜角为16°,20°,24°,28°,32°单头(即16°CO,20°CO,24°CO,28°CO和32°CO)和32°双头(即2-32°CO)6种周向重叠三分螺旋折流板换热器(cothSTHXs)以及作为对比的弓形折流板换热器的进行数值模拟,并与已有的实验数据进行比较。采用速度矢量图和压力云图叠加速度矢量的方式分析特殊剖面上局部参数。研究结果表明:数值模拟结果与实际吻合良好。螺旋折流板方案壳侧通道存在迪恩涡二次流,相邻折流板重叠区内的管排可抑制缺口泄漏,周向重叠结构有利于强化传热;在相同流量下,壳侧换热系数随倾斜角的增大而减小。20°CO倾斜角方案的性能最优,在相同压降下,其壳侧换热系数比其他方案的系数高,且流道内的迪恩涡二次流明显较强。弓形折流板方案的性能最差,其流道中存在流动死区,且壳侧压降远高于所有螺旋折流板方案;在相同压降下,其壳侧换热系数最低,但在相同流量下的壳侧换热系数在所有方案中位列第3,紧随16°CO和20°CO方案之后。%The six circumferential overlap trisection helical baffle shell-and-tube heat exchangers (cothSTHXs) with single thread but baffle incline angles of 16°, 20°, 24°, 28°, 32° (16°CO, 20°CO, 24°CO, 28°CO, 32°CO) as well as double thread and baffle incline angle of 32° (2-32°CO), as opposed to a segment baffle heat exchanger, were numerically simulated and compared with the available experimental data. Local parameter distributions of the velocity vectors or pressure contours plus velocity vectors on special sections were plotted and analyzed. The results show that the simulation results are satisfactory and in agreement with tests. The Dean Vortex secondary flow and bypass leakage between adjacent baffles in the spiral channel play essential roles in the heat transfer enhancement of the cothSTHXs. The shell-side heat transfer coefficient

  7. 高分辨MRI颅内动脉瘤瘤壁环形强化的临床意义%Clinical significance of circumferential aneurysmal wall enhancement of intracranial aneurysms in high-resolution magnetic resonance imaging

    Institute of Scientific and Technical Information of China (English)

    付其昌; 管生; 郭新宾; 徐浩文

    2015-01-01

    目的:探讨高分辨MRI(HR-MRI)中颅内动脉瘤瘤壁环形强化(CAWE)的临床意义。方法回顾性分析2014年10月至2015年7月收治的41例行钆剂增强3.0 T HR-MRI检查的颅内动脉瘤患者的影像及临床资料;由两名有经验的神经血管影像医师独立阅片,确定患者的颅内动脉瘤瘤壁是否出现CAWE。其中颅内不稳定动脉瘤患者25例,颅内稳定动脉瘤患者16例。对两名医师诊断CAWE结果的一致性进行kappa 检验;比较两组患者颅内动脉瘤影像特征CAWE、个数、位置、大小等以及性别、年龄、吸烟史、饮酒史、高血压、糖尿病等,临床危险因素组间比较采用χ2检验。结果41例患者共发现颅内动脉瘤47个,其中颅内不稳定动脉瘤29个、颅内稳定动脉瘤18个;两名有经验的神经血管影像医师诊断CAWE 结果的一致性较好(κ=0.828,95% CI:0.668~0.989);颅内不稳定动脉瘤的CAWE明显较颅内稳定动脉瘤多,差异有统计学意义[75.9%(22/29)比33.3%(6/18);χ2=8.341,P =0.004];颅内不稳定动脉瘤患者的年龄<60岁者较颅内稳定动脉瘤者多,差异有统计学意义[68.0%(17/25)比31.2%(5/16);χ2=5.299,P =0.021];而两组颅内动脉瘤均个数、位置、大小以及包括性别、吸烟史、饮酒史、高血压、糖尿病的差异均无统计学意义(P >0.05)。结论 CAWE多明显见于颅内不稳定动脉瘤,能将症状性、形态改变及破裂的颅内动脉瘤与颅内稳定动脉瘤鉴别。%Objective To investigate the clinical significance of circumferential aneurysmal wall enhancement (CAWE)in high-resolution magnetic resonance imaging. Methods The imaging and clinical data of 41 patients with intracranial aneurysm underwent gadolinium-enhanced 3. 0 T HR-MRI from October 2014 to July 2015 were analyzed retrospectively. Two experienced neurovascular radiologists read the vascular

  8. 小流量下周向弯曲叶片叶顶泄漏流特性的实验研究%The study on the unsteady characteristics of tip leakage flow in circumferential skewed axial fan under off-design conditions

    Institute of Scientific and Technical Information of China (English)

    金光远; 吴亚东; 欧阳华; 杜朝辉

    2013-01-01

    对带有周向前弯和周向后弯叶片的低压轴流风机,采用壁面动态压力测量技术试验研究了小流量工况下叶顶泄漏流的频谱特性.在机匣壁面布置动态压力传感器捕捉由泄漏流诱发的壁面压力信号,基于测量结果详细阐述了小流量工况下周向弯曲叶片叶顶泄漏流诱发的流动不稳定性.结果表明:随流量的降低,泄漏涡引起的频率分量逐步凸显,并向更低频段转移,具有明显的宽频特性;周向弯曲叶片控制了泄漏流动从前缘至尾缘的传播速度,前弯叶轮的泄漏流动传播速度最慢,后弯叶轮次之;周向弯曲叶片对叶顶泄漏流诱发的不稳定流动具有控制作用.%In this paper, the unsteady characteristics of tip leakage flow in axial fans with circumferential skewed blades were investigated at off-design conditions using wall pressure test. The static pressure fluctuations near blade tip were captured at off-design conditions by using pressure sensors mounted on casing wall. From the measured results, instantaneous characteristics of tip leakage flow in circumferential skewed fans were analyzed. Based on the measurement results, as the flow rate decreases, the broadband frequency components of tip leakage flow tend to increase in the low frequency domain. The forward-skewed blade is found to be effective in controlling tip leakage flow to expand from blade leading edge to tail edge, the TLF component of the BSK rotor propagates more fast than that of FSK rotor. The instability of tip leakage flow under off-design conditions is controlled by circumferential skewed blades.

  9. Degradation of aromatic compounds and degradative pathway of 4-nitrocatechol by Ochrobactrum sp. B2.

    Science.gov (United States)

    Zhong, Qiuzan; Zhang, Haiyan; Bai, Wenqin; Li, Mei; Li, Baotong; Qiu, Xinghui

    2007-12-01

    The potential capacity of a soil methyl parathion-degrading bacterium strain, Ochrobactrum sp. B2, for degrading various aromatic compounds were investigated. The results showed B2 was capable of degrading diverse aromatic compounds, but amino-substituted benzene compounds, at a concentration up to 100 mg L(-1) in 4 days. B2 could use 4-nitrocatechol (4-NC) as a sole carbon and energy source with release of nitrite ion. The pathway for 4-NC degradation via 1,2,4-benzenetriol (BT) and hydroquinone (HQ) formation in B2 was proposed based on the identification and quantification of intermediates by gas chromatography-mass spectrometry (GC-MS), and high performance liquid chromatography (HPLC). Degradation studies carried out on a plasmid-cured derivative showed that the genes for 4-NC degradative pathway was plasmid-borne in B2, suggesting that B2 degrades both p-nitrophenol and 4-NC by enzymes encoded by genes on the same plasmid.

  10. Degradation of toluene-2,4-diamine by persulphate: kinetics, intermediates and degradation pathway.

    Science.gov (United States)

    Jiang, Yong-hai; Zhang, Jin-bao; Xi, Bei-dou; An, Da; Yang, Yu; Li, Ming-xiao

    2015-01-01

    In this study, the degradation of toluene-2,4-diamine (TDA) by persulphate (PS) in an aqueous solution at near-neutral pH was examined. The result showed that the degradation rate of TDA increased with increasing PS concentrations. The optimal dosage of PS in the reaction system was determined by efficiency indicator (I) coupling in the consumption of PS and decay half-life of TDA. Calculation showed that 0.74 mM of PS was the most effective dosage for TDA degradation, at that level the maximum I of 24.51 was obtained. PS can oxidize TDA for an extended reaction time period. Under neutral condition without activation, four degradation intermediates, 2,4-diamino-3-hydroxy-5-sulfonicacidtoluene, 2,4-diaminobenzaldehyde, 2,4-bis(vinylamino)benzaldehyde and 3,5-diamino-4-hydroxy-2-pentene, were identified by high-performance liquid chromatography-mass spectrometry. The tentative degradation pathway of TDA was proposed as well. It was found that hydroxyl radical played an important role in degradation of TDA with the activation of Fe2+, whereas PS anion and sulphate radicals were responsible for the degradation without activation of Fe2+.

  11. Land degradation is indicative: proxies of forest land degradation in Ghana

    Directory of Open Access Journals (Sweden)

    K. Peprah

    2015-10-01

    Full Text Available : How is land degradation measured? The aim of the paper is to address this research question. At the premise, the paper states that land degradation as one of the truth claims of environmental science, is not directly monitored and detectable. Observers rely on indicators to know land degradation. The issues are illuminated by theoretical reference based on the notion of critical political ecology which tries to combine realist biophysical predictions and socio-political constructions. A methodology which mixes literature review, group discussion and field work produces a set of indicators of land degradation. Indigenous farmers used the indicators to spot land degradation in the forest ecosystem of Ghana. The results reveal physical indicators of iron pan formation in farms, uphill and downhill respective lost and gain of soil fertility, roots and building foundations exposed by soil erosion and river channels that do not carry running water even in the raining season. There are biological indicators of invasive species and termite infestations as well as socioeconomic indicators of poverty implicitly taken as indicators of land degradation. The paper concludes that land degradation includes multifaceted set of processes measured by variable and error-filled indicators operating at various spatial, temporal, economic and cultural scales.

  12. Microbially influenced degradation of concrete structures

    Science.gov (United States)

    Rogers, Robert D.; Hamilton, Melinda A.; Nelson, Lee O.

    1998-03-01

    Steel reinforced concrete is the most widely used construction material in the world. The economic costs of repair or replacement of environmentally damaged concrete structures is astronomical. For example, half of the concrete bridges in the Federal Department of Transportation highway system are in need of major repairs. Microbially influenced degradation of concrete (MID) is one of the recognized degradative processes known to adversely affect concrete integrity. It is not possible to assign a specific percent of effect to any of these processes. However, MID has been shown to be as aggressive as any of the physical/chemical phenomena. In addition, the possibility exists that there is a synergism which results in cumulative effects from all the processes. Three groups of bacteria are known to promote MID. Of these, sulfur-oxidizing bacteria (SOB) are the most aggressive. Much is known about the nutritional needs of these bacteria. However, there has not been a biological linkage established between the presence of environmental, polluting sulfur sources and the degradation of concrete structures. It has been shown that the environmental pollutants sulfur dioxide and sulfite can be utilized by active SOB for the biological production of sulfuric acid. Therefore, it is not a reach of reality to assume that SOB exposed to these pollutants could have a major impact on the degradation of concrete structures. But, until the environment sulfur loop is closed it will not be possible to calculate how important SOB activity is in initiating and promoting damage.

  13. Analysis of thermally-degrading, confined HMX

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, M.L.; Schmitt, R.G.; Renlund, A.M.

    1996-12-01

    The response of a thermally-degrading, confined HMX pellet is analyzed using a Reactive Elastic-Plastic (REP) constitutive model which is founded on the collapse and growth of internal inclusions resulting from physical and chemical processes such as forced displacement, thermal expansion, and/or decomposition. Axial stress predictions compare adequately to data. Deficiencies in the model and future directions are discussed.

  14. Pt/C Fuel Cell Catalyst Degradation

    DEFF Research Database (Denmark)

    Zana, Alessandro

    This thesis investigates the degradation behavior of Pt/C catalysts under simulated automotive conditions. By using the “tool box” synthesis method the Pt loading has been changed from low to high Pt loadings, therefore permitting to study the role of Pt on the degradation of high surface area (HSA......) Pt/C catalyst. Diverse degradation mechanisms have been found to be responsible for the electrochemical surface area loss (ECSA). The different degradation mechanisms have been found to be dependent from the diverse potential windows applied during the stress test. Furthermore the synthesis approach...... nanoparticles (NPs). TiO2@C was synthesized by heat treatment in C2H2 and subsequently loaded with Pt NPs. Pt/TiO2@C was tested and compared with Pt/C and Pt/TiO2 prepared using the same colloidal stock solution. Similar ECSA values were reached on Pt/TiO2@C and Pt/C while Pt/TiO2 fails to reach high ECSA...

  15. Modeling Degradation in Solid Oxide Electrolysis Cells

    Energy Technology Data Exchange (ETDEWEB)

    Manohar S. Sohal; Anil V. Virkar; Sergey N. Rashkeev; Michael V. Glazoff

    2010-09-01

    Idaho National Laboratory has an ongoing project to generate hydrogen from steam using solid oxide electrolysis cells (SOECs). To accomplish this, technical and degradation issues associated with the SOECs will need to be addressed. This report covers various approaches being pursued to model degradation issues in SOECs. An electrochemical model for degradation of SOECs is presented. The model is based on concepts in local thermodynamic equilibrium in systems otherwise in global thermodynamic no equilibrium. It is shown that electronic conduction through the electrolyte, however small, must be taken into account for determining local oxygen chemical potential, , within the electrolyte. The within the electrolyte may lie out of bounds in relation to values at the electrodes in the electrolyzer mode. Under certain conditions, high pressures can develop in the electrolyte just near the oxygen electrode/electrolyte interface, leading to oxygen electrode delamination. These predictions are in accordance with the reported literature on the subject. Development of high pressures may be avoided by introducing some electronic conduction in the electrolyte. By combining equilibrium thermodynamics, no equilibrium (diffusion) modeling, and first-principles, atomic scale calculations were performed to understand the degradation mechanisms and provide practical recommendations on how to inhibit and/or completely mitigate them.

  16. Developmentally regulated sphingolipid degradation in Leishmania major.

    Directory of Open Access Journals (Sweden)

    Ou Zhang

    Full Text Available Leishmania parasites alternate between extracellular promastigotes in sandflies and intracellular amastigotes in mammals. These protozoans acquire sphingolipids (SLs through de novo synthesis (to produce inositol phosphorylceramide and salvage (to obtain sphingomyelin from the host. A single ISCL (Inositol phosphoSphingolipid phospholipase C-Like enzyme is responsible for the degradation of both inositol phosphorylceramide (the IPC hydrolase or IPCase activity and sphingomyelin (the SMase activity. Recent studies of a L. major ISCL-null mutant (iscl(- indicate that SL degradation is required for promastigote survival in stationary phase, especially under acidic pH. ISCL is also essential for L. major proliferation in mammals. To further understand the role of ISCL in Leishmania growth and virulence, we introduced a sole IPCase or a sole SMase into the iscl(- mutant. Results showed that restoration of IPCase only complemented the acid resistance defect in iscl(- promastigotes and improved their survival in macrophages, but failed to recover virulence in mice. In contrast, a sole SMase fully restored parasite infectivity in mice but was unable to reverse the promastigote defects in iscl(-. These findings suggest that SL degradation in Leishmania possesses separate roles in different stages: while the IPCase activity is important for promastigote survival and acid tolerance, the SMase activity is required for amastigote proliferation in mammals. Consistent with these findings, ISCL was preferentially expressed in stationary phase promastigotes and amastigotes. Together, our results indicate that SL degradation by Leishmania is critical for parasites to establish and sustain infection in the mammalian host.

  17. Overview of Field Experience - Degradation Rates & Lifetimes

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Dirk; Kurtz, Sarah

    2015-09-14

    The way a PV module fails may depend not only on its design and the materials used in its construction, but also on the weather it experiences, the way it is mounted, and the quality control during its manufacture. This presentation gives an overview of Field Experience - what degradation rates and what lifetimes are being observed in various regions.

  18. Multiscale degradations of storage ring FEL optics

    CERN Document Server

    Gatto, A; Amra, C; Boccara, C; Couprie, Marie Emmanuelle; De Ninno, G; Feigl, T; Garzella, D; Grewe, M; Kaiser, N; Marsi, M; Paoloni, S; Reita, V; Roger, J P; Torchio, P; Trovò, M; Walker, R; Wille, K

    2002-01-01

    The advanced understanding of the complete degradation phenomena is crucial in order to develop robust optics for FEL. Under very harsh Synchrotron Radiation conditions, results show that multiscale wavelength damages could be observed, inducing local crystalline structure modifications of the high optical index material with a severe increase of the surface roughness.

  19. Thermooxidation Stability of Some Degraded Xyloglucans

    Science.gov (United States)

    Matisová-Rychlá, L.; Rychlý, J.; Ebringerová, A.; Csomorová, K.; Malovíková, A.

    2008-08-01

    The effect on chemiluminescence intensity ant thus on thermal oxidation of the initial molar mass of xyloglucans has been examined. The molar mass was pre-set by degradation using ultrasonic and/or gamma-rays. It has been demonstrated that the initial molar mass has a significant effect on the course of xyloglucan oxidation.

  20. Aeromonas chitinase degrades chironomid egg masses.

    Science.gov (United States)

    Laviad, Sivan; Golan, Amnon; Shaked, Tamar; Vaizel-Ohayon, Dalit; Halpern, Malka; Pick, Elah

    2016-02-01

    Chironomids are freshwater insects that undergo a complete metamorphosis of four life stages. Chironomid egg masses can be degraded by Vibrio cholerae and some Aeromonas species. Egg mass degradation by V. cholerae requires haemagglutinin protease activity. Our aim was to identify the egg mass degrading (EMD) factor secreted by Aeromonas dhkanesis 3K1C15. Following the hypothesis that the EMD factor of A. dhkanesis is also a protease, secreted proteases were screened, but none of them proved to have the same properties as the EMD factor. Using conventional protein purification methods, we found that the active fraction included chitinases. We further confirmed chitin as a building block of the egg masses. Interestingly, by supplementing bacterial growth media with chitin, we observed unexpected EMD factor activity in Aeromonas isolates that initially were not able to degrade egg masses. Accordingly, we concluded that although strain 3K1C15 secretes chitinases constitutively, most Aeromonas strains secrete chitinases inductively. Induction of chitinases in nature presumably occurs when bacteria are attached to the egg mass habitat, in which chitin is abundant. Considering that chitinases are highly conserved across bacteria phyla, we assume that the role of this enzyme in the bacteria-insect interplay could be wider than is currently thought.

  1. Reactor for Photocatalytic Degradation of Chloroform

    DEFF Research Database (Denmark)

    Simonsen, Morten Enggrob; Søgaard, Erik Gydesen

    In the present study a new type of continuous photoreactor is developed in which the TiO2 catalyst is immobilized on the surface of quartz tubes surrounding the UV lamps and on the internal surface of the reactor walls. The study showed that an initial concentration chloroform of 7 mg/l was degra......In the present study a new type of continuous photoreactor is developed in which the TiO2 catalyst is immobilized on the surface of quartz tubes surrounding the UV lamps and on the internal surface of the reactor walls. The study showed that an initial concentration chloroform of 7 mg....../l was degraded in a period of 500 hour. The kinetics of the degradation of chloroform in the flow reactor was found to obey Langmuir-Hinshelwood kinetics. The investigation also showed that the reactor design has a significant influence on the rate of degradation, as it was observed that the position...... of the coated lamp in the reactor yield different degradation rates....

  2. Biological degradation of plastics: a comprehensive review.

    Science.gov (United States)

    Shah, Aamer Ali; Hasan, Fariha; Hameed, Abdul; Ahmed, Safia

    2008-01-01

    Lack of degradability and the closing of landfill sites as well as growing water and land pollution problems have led to concern about plastics. With the excessive use of plastics and increasing pressure being placed on capacities available for plastic waste disposal, the need for biodegradable plastics and biodegradation of plastic wastes has assumed increasing importance in the last few years. Awareness of the waste problem and its impact on the environment has awakened new interest in the area of degradable polymers. The interest in environmental issues is growing and there are increasing demands to develop material which do not burden the environment significantly. Biodegradation is necessary for water-soluble or water-immiscible polymers because they eventually enter streams which can neither be recycled nor incinerated. It is important to consider the microbial degradation of natural and synthetic polymers in order to understand what is necessary for biodegradation and the mechanisms involved. This requires understanding of the interactions between materials and microorganisms and the biochemical changes involved. Widespread studies on the biodegradation of plastics have been carried out in order to overcome the environmental problems associated with synthetic plastic waste. This paper reviews the current research on the biodegradation of biodegradable and also the conventional synthetic plastics and also use of various techniques for the analysis of degradation in vitro.

  3. Controlling the Degradation of Bioresorbable Polymers

    Science.gov (United States)

    Moritz, Istvan; Crowley, Brian; Brundage, Elizabeth; Rende, Deniz; Ozisik, Rahmi

    Bioresorbable polymers play a vital role in the development of implantable materials that are used in surgical procedures, controlled drug delivery systems; and tissue engineering scaffolds. The half-life of common bioresorbable polymers ranges from 3 to over 12 months and slow bioresorption rates of these polymers restrict their use to a limited set of applications. The use of embedded enzymes was previously proposed to control the degradation rate of bioresorbable polymers, and was shown to decrease average degradation time to about 0.5 months. In this study, electromagnetic actuation of iron oxide magnetic nanoparticles embedded in an encapsulant polymer, poly(ethyleneoxide), PEO, was employed to initiate enzyme assisted degradation of bioresorbable polymer poly(caprolactone), PCL. Results indicate that the internal temperature of iron oxide magnetic nanoparticle doped PEO samples can be increased via an alternating magnetic field, and temperature increase depends strongly on nanoparticle concentration and magnetic field parameters. The temperature achieved is sufficient to relax the PEO matrix and to enable the diffusion of enzymes from PEO to a surrounding PCL matrix. Current studies are directed at measuring the degradation rate of PCL due to the diffused enzyme. This material is based upon work supported by the National Science Foundation under Grant No. CMMI-1538730.

  4. Atmospheric degradation mechanism of organic sulfur compounds

    Energy Technology Data Exchange (ETDEWEB)

    Benter, T.; Arsene, C.

    2002-02-01

    In the present work a detailed product study has been performed on the OH radical initiated oxidation of dimethyl sulphide and dimethyl sulphoxide, under different conditions of temperature, partial pressure of oxygen and NO{sub x} concentration, in order to better define the degradation mechanism of the above compounds under conditions which prevail in the atmosphere. (orig.)

  5. Degradation of apple fruit xyloglucan by endoglucanase.

    NARCIS (Netherlands)

    Vincken, J.P.; Beldman, G.; Niessen, W.M.A.; Voragen, A.G.J.

    1996-01-01

    A purified, alkali-extractable apple fruit xyloglucan (APfxg) was treated by endoglucanase (endoIV) from Trichoderma viride. The degradation products were fractionated by size-exclusion chromatography on BioGel P-2; the pentamer to dodecamer fractions were further fractionated by semi-preparative hi

  6. Anaerobic microbial LCFA degradation in bioreactors

    NARCIS (Netherlands)

    Sousa, D.Z.; Pereira, M.A.; Alves, J.I.; Smidt, H.; Stams, A.J.M.; Alves, M.M.

    2008-01-01

    This paper reviews recent results obtained on long-chain fatty acids (LCFA) anaerobic degradation. Two LCFA were used as model substrates: oleate, a mono-unsaturated LCFA, and palmitate, a saturated LCFA, both abundant in LCFA-rich wastewaters. 16S rRNA gene analysis of sludge samples submitted to c

  7. Development of Nuclear Materials and Degradation Database

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Ho Sang [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of); Park, Heung Bae [KEPCO Engineering and Construction Company, Seongnam (Korea, Republic of)

    2010-10-15

    There are about 440 operating nuclear power reactors in the world including 20 units from Korea. The average age of the reactors is more than 20 years and many of them are approaching to their original 30 or 40 years licensing terms. Even though some failures were reported in components or pipes of nuclear power plants (NPPs), these NPPs are considered to be too valuable to stop their operation at the end of design life. Therefore, the long-term operation of NPPs has become a worldwide trend based on technical and economic consideration. In order to ensure safe long-term operation of NPPs, it is increasingly necessary to adopt new approaches to deal with nuclear materials aging and degradation. Proactive Material Degradation Assessment (PMDA) is one of the key elements of these new approaches. Many kinds of background information such as materials and degradation history of components or piping in NPP plant are also needed for PMDA by the experts. Nuclear Materials and Degradation Database is being developed as a part of Nuclear Technology Revolution Project (NTRP) funded by the Ministry of Knowledge Economy (MKE)

  8. Microbial degradation of propoxur in turfgrass soil.

    Science.gov (United States)

    Ou, L T; Nkedi-Kizza, P; Cisar, J L; Snyder, G H

    1992-10-01

    This study was conducted to determine the degradation rates in turfgrass soil over a 12-month period after a single field application of propoxur and to isolate microorganisms from the soil capable of degrading the insecticide. Soil samples were collected from a turfgrass experimental site near Fort Lauderdale, FL one week before the field application of propoxur, and over a 12-month period after the field application. Mineralization rates in surface (0-15 cm depth) and subsurface (15-30 cm depth) soil samples collected before the field application were low. Mineralization in surface and subsurface samples collected 1, 6 and 8 months after the field application was much higher than for corresponding samples collected before the field application. Mineralization in the subsurface samples collected 12 months after the field application had reverted back to the similar rate for the corresponding sample collected before field application. Half-life values (t1/2) for propoxur showed similar trends to the results of mineralization. After a single application of propoxur, degradation in turfgrass soil was enhanced. Such enhancement lasted less than 12 months for the subsurface, but more than 12 months for the surface. A strain of Arthrobacter sp. capable of degrading propoxur was isolated from the soil.

  9. Chemical Degradation of PCBs in Alaskan Soils

    Science.gov (United States)

    2011-04-01

    approximate 20 to 30% reduction of Aroclor concentration compared to the controls. Tests applying Tween 80 at 15% (w/w) with NaOH at 2% (w/w) indicated that...the Tween 80 increased PCB release from soil, but no significant PCB degradation was found. An experiment was then conducted to investigate the use of

  10. Bacterial enzymes involved in lignin degradation

    NARCIS (Netherlands)

    de Gonzalo, Gonzalo; Colpa, Dana I; Habib, Mohamed H M; Fraaije, Marco W

    2016-01-01

    Lignin forms a large part of plant biomass. It is a highly heterogeneous polymer of 4-hydroxyphenylpropanoid units and is embedded within polysaccharide polymers forming lignocellulose. Lignin provides strength and rigidity to plants and is rather resilient towards degradation. To improve the (bio)p

  11. Lactose contaminant as steroid degradation enhancer

    NARCIS (Netherlands)

    Nieuwmeyer, Florentine; Maarschalk, Kees van der Voort; Vromans, Herman

    2008-01-01

    Purpose. By pharmaceutical processes and in the presence of solid excipients physical-chemical changes are known to occur, leading to increased rate of chemical degradation. The purpose of this work was to determine the critical aspects in the stability of a steroid in the presence of a commonly use

  12. Land degradation: a challenge to Ethiopia.

    Science.gov (United States)

    Taddese, G

    2001-06-01

    Land degradation is a great threat for the future and it requires great effort and resources to ameliorate. The major causes of land degradation in Ethiopia are the rapid population increase, severe soil loss, deforestation, low vegetative cover and unbalanced crop and livestock production. Inappropriate land-use systems and land-tenure policies enhance desertification and loss of agrobiodiversity. Utilization of dung and crop residues for fuel and other uses disturbs the sustainability of land resources. The supply of inputs such as fertilizer, farm machinery and credits are very low. The balance between crop, livestock, and forest production is disturbed, and the farmer is forced to put more land into crop production. For environmentally and socially sustainable development, there is an urgent need to promote awareness and understanding of the interdependence of natural, socioeconomic, and political systems at local and national levels. Understanding the current status and causes of land degradation is very important. This paper reveals the important elements of land degradation in Ethiopia and suggests possible solutions that may help to ameliorate the situation.

  13. Microbial degradation of MTBE in reactors

    DEFF Research Database (Denmark)

    Waul, Christopher Kevin; Arvin, Erik; Schmidt, Jens Ejbye

    2007-01-01

    , toluene, ethylbenzene and xylenes, may reduce the removal rates of MTBE, or prevent its removal in reactors. With mathematical modelling, the long startup time required for some MTBE degrading reactors could be predicted. Long startup times of up to 200 days were due to the low maximum growth rate...

  14. Dynamics of cell degradation. [nickel cadmium batteries

    Science.gov (United States)

    Mcdermott, P. P.

    1978-01-01

    The use of chemical and physical data as a supplement to linear regression models in the prediction of cell failure is discussed. Principal factors to be considered are the positive thickness and weight, and the negative thickness. A model for cell degradation and failure in accelerated life test cells is presented and predictions based on a teardown analysis are included.

  15. Anaerobic degradation of linear alkylbenzene sulfonate

    DEFF Research Database (Denmark)

    Mogensen, Anders Skibsted; Haagensen, Frank; Ahring, Birgitte Kiær

    2003-01-01

    increases during anaerobic stabilization due to transformation of easily degradable organic matter. Hence, LAS is regarded as resistant to biodegradation under anaerobic conditions. We present data from a lab-scale semi-continuously stirred tank reactor (CSTR) spiked with linear dodecylbenzene sulfonate (C...

  16. Purification of highly chlorinated dioxins degrading enzyme

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, K.; Furuichi, T.; Koike, K.; Kuboshima, M. [Hokkaido Univ. (Japan). Division of Environment Resource Engineering, Graduate School of Engineering

    2004-09-15

    Soil contamination caused by dioxins in and around sites of incinerators for municipal solid waste (MSW) is a concern in Japan. For example, scattering wastewater from a wet gas scrubber at an MSW incinerator facility in Nose, Osaka caused soil and surface water contamination. The concentration of dioxins in the soil was about 8,000 pg-TEQ/g. Other contamination sites include soils on which fly ash has been placed directly or improperly stored and landfill sites that have received bottom and fly ash over a long period. Some countermeasures are required immediately at these dioxins-contaminated sites. We have previously developed bioreactor systems for dioxin-contaminated water and soil. We have shown that a fungus, Pseudallescheria boydii (P. boydii), isolated from activated sludge treating wastewater that contained dioxins, has the ability to degrade highly chlorinated dioxins. A reaction product of octachlorinated dibenzo-p-dioxin (OCDD) was identified as heptachlorinated dibenzo-p-dioxin. Therefore, one of the pathways for degradation of OCDD by this fungus was predicted to be as follows: OCDD is transformed by dechlorination and then one of the remaining aromatic rings is oxidized. To apply P. boydii to on-site technologies (e.g., bioreactor systems), as well as in situ technologies, enzyme treatment using a dioxin-degrading enzyme from P. boydii needs to be developed because P. boydii is a weak pathogenic fungus, known to cause opportunistic infection. As a result, we have studied enzyme purification of nonchlorinated dioxin, namely, dibenzo-pdioxin (DD). However, we did not try to identify enzymes capable of degrading highly chlorinated dioxins. This study has elucidated a method of enzyme assay for measuring OCDD-degrading activity, and has attempted to purify OCDD-degrading enzymes from P. boydii using enzyme assay. In addition, as first step toward purifying 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), 2,3,7,8-TCDD degradation tests were carried out

  17. Radiation degradation of alginate and some results of biological effect of degraded alginate on plants

    Energy Technology Data Exchange (ETDEWEB)

    Hien, N.Q.; Hai, L.; Luan, L.Q.; Hanh, T.T. [Nuclear Research Institute, Dalat (Viet Nam); Nagasawa, Naotsugu; Yoshii, Fumio; Makuuchi, Keizo; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2000-03-01

    Radiation degradation yields (Gd) of alginate in aqueous solution with different concentration were determined by viscometry method. The relationship between Gd and the alginate concentration was found out as: Gd=33.5 x C{sup -0.68}, with C% (w/v) and dry alginate referred to C=100%. An empirical equation for preparing degraded alginate with the desired low viscometry average molecular weight (Mv) by radiation was proposed. Alginate extracted directly horn seaweed'Sagassum, degraded by radiation was used for field experiments and results of the biological effect on plants (tea, carrot, chrysanthemum) were presented. (author)

  18. Photocatalytic degradation kinetics in Rhodamine B dye degradation with poriferous TiO2 photocatalyst

    Institute of Scientific and Technical Information of China (English)

    WANG Zheng-ping; JIAO Cai-shan; CHEN Xing-juan

    2006-01-01

    A type of poriferous TiO2 material was prepared using cetyl trimethyl ammonium bromide as a template agent and butyl tetra titanate as a precursor. Through studying the photocatalytic kinetic activity of Rhodamine B photocatalytic degradation reaction with a UV-1601 PC ultraviolet-visible spectrophotometer, the photocatalytic degradation process of Rhodamine B was found to not correspond to the firstorder kinetic process completely. According to the reaction phenomenon, the photocatalytic degradation process of Rhodamine B with poriferous TiO2 involved two irreversible reactions. The kinetic model was tested using experimental data.

  19. Restoring Soil Quality to Mitigate Soil Degradation

    Directory of Open Access Journals (Sweden)

    Rattan Lal

    2015-05-01

    Full Text Available Feeding the world population, 7.3 billion in 2015 and projected to increase to 9.5 billion by 2050, necessitates an increase in agricultural production of ~70% between 2005 and 2050. Soil degradation, characterized by decline in quality and decrease in ecosystem goods and services, is a major constraint to achieving the required increase in agricultural production. Soil is a non-renewable resource on human time scales with its vulnerability to degradation depending on complex interactions between processes, factors and causes occurring at a range of spatial and temporal scales. Among the major soil degradation processes are accelerated erosion, depletion of the soil organic carbon (SOC pool and loss in biodiversity, loss of soil fertility and elemental imbalance, acidification and salinization. Soil degradation trends can be reversed by conversion to a restorative land use and adoption of recommended management practices. The strategy is to minimize soil erosion, create positive SOC and N budgets, enhance activity and species diversity of soil biota (micro, meso, and macro, and improve structural stability and pore geometry. Improving soil quality (i.e., increasing SOC pool, improving soil structure, enhancing soil fertility can reduce risks of soil degradation (physical, chemical, biological and ecological while improving the environment. Increasing the SOC pool to above the critical level (10 to 15 g/kg is essential to set-in-motion the restorative trends. Site-specific techniques of restoring soil quality include conservation agriculture, integrated nutrient management, continuous vegetative cover such as residue mulch and cover cropping, and controlled grazing at appropriate stocking rates. The strategy is to produce “more from less” by reducing losses and increasing soil, water, and nutrient use efficiency.

  20. 浅论风电叶片真空灌注根端环向布管工艺发白的解决和控制%The Solution of The Dry Spot in VARTM Using The Circumferential Direction Piping Layout at The Turbine Blade Root

    Institute of Scientific and Technical Information of China (English)

    徐文军

    2015-01-01

    本文运用相关质量管理知识,研究1.5MW叶片根端环向布管真空灌注成型后发白的形成原因,提出叶片根端纵向布管和原树脂脱泡的方案,可以预防和控制叶片根端发白,提高叶片产品质量。%Studying the reasons of dry spot in VARTM using the circumferential direction piping layout at the 1.5MW Blade Root, proposing the solution that is longitudinal direction piping layout and raw resin degassing in order to prevent and control the defect of dry spot at the blade root .then improving the blade quality.

  1. Phylogenetic and degradation characterization of Burkholderia cepacia WZ1 degrading herbicide quinclorac.

    Science.gov (United States)

    Lü, Zhenmei; Min, Hang; Wu, Shuwen; Ruan, Aidong

    2003-11-01

    Strain WZI capable of degrading quinclorac was isolated from a pesticide manufactory soil and considered to be Burkholderia cepacia, belonged to bacteria, Proteobacteria, beta-Proteobacteria, based on morphology, physio-biochemical properties, whole cell fatty acid analysis and a partial sequencing of 16S rDNA. Strain WZ1 decomposed 90% of quinclorac at original concentration of 1000 mg L(-1) within 11 days. GC/MS analysis showed that the strain degraded quinclorac to 3,7-dichloro-8-quinoline and the cracked residue 2-chloro, 1,4-benzenedicarboxylic acid, indicating that the metabolic pathway was initiated by process of decarboxylation followed by cleavage of the aromatic ring. Stain WZ1 was also able to degrade some other herbicides and aromatic compounds, including 2,4,5-T, phenol, naphthalene and hydrochinone etc. This paper describes for the first time Phylogenetic and degradation characterization of a pure bacterium which, is able to mineralize quinclorac.

  2. Kinetic parameters of the thermal degradation of the PP and nondegraded and degraded HDPE blends

    Energy Technology Data Exchange (ETDEWEB)

    Albano, C.; Freitas, E. [Universidad Central de Venezuela, Caracas (Venezuela)

    1996-12-31

    We study the thermodegradative behavior of PP, of non-degraded and degraded HDPE and their blends, in order to analyze the thermal stability of such materials. Van-Krevelen (V-K), Coats-Redfern (C-R) and Horowitz-Metzger (H-M) integral methods as well as the Freeman-Carroll (F-C) differential one, were used to determine the kinetic parameters. The activation energy (E{sub a}) obtained for the PP mixed with non-degraded HDPE (5 to 50%) is lower than the E{sub a} correspondent to pure polymers and does not depend on the HDPE concentration. Blends of degraded materials, show an approximate value of E{sub a} of 200 kJ/mol for mixtures with concentrations by weight of HDPE up to 20%, but its value decreases drastically with higher concentrations. 11 refs., 2 tabs.

  3. Characterization of Methane Degradation and Methane-Degrading Microbes in Alaska Coastal Water

    Energy Technology Data Exchange (ETDEWEB)

    Kirchman, David L. [Univ. of Delaware, Lewes, DE (United States)

    2012-03-29

    The net flux of methane from methane hydrates and other sources to the atmosphere depends on methane degradation as well as methane production and release from geological sources. The goal of this project was to examine methane-degrading archaea and organic carbon oxidizing bacteria in methane-rich and methane-poor sediments of the Beaufort Sea, Alaska. The Beaufort Sea system was sampled as part of a multi-disciplinary expedition (Methane in the Arctic Shelf or MIDAS) in September 2009. Microbial communities were examined by quantitative PCR analyses of 16S rRNA genes and key methane degradation genes (pmoA and mcrA involved in aerobic and anaerobic methane degradation, respectively), tag pyrosequencing of 16S rRNA genes to determine the taxonomic make up of microbes in these sediments, and sequencing of all microbial genes (metagenomes ). The taxonomic and functional make-up of the microbial communities varied with methane concentrations, with some data suggesting higher abundances of potential methane-oxidizing archaea in methane-rich sediments. Sequence analysis of PCR amplicons revealed that most of the mcrA genes were from the ANME-2 group of methane oxidizers. According to metagenomic data, genes involved in methane degradation and other degradation pathways changed with sediment depth along with sulfate and methane concentrations. Most importantly, sulfate reduction genes decreased with depth while the anaerobic methane degradation gene (mcrA) increased along with methane concentrations. The number of potential methane degradation genes (mcrA) was low and inconsistent with other data indicating the large impact of methane on these sediments. The data can be reconciled if a small number of potential methane-oxidizing archaea mediates a large flux of carbon in these sediments. Our study is the first to report metagenomic data from sediments dominated by ANME-2 archaea and is one of the few to examine the entire microbial assemblage potentially involved in

  4. 髌骨周围去神经化对保留髌骨的全膝关节置换术后影响的meta分析%Circumferential electrocautery of the patellar in primary total knee replacement without patella replacement: a meta-analysis and systematic review

    Institute of Scientific and Technical Information of China (English)

    葛兆刚; 樊立宏; 刘琪; 时志斌; 党晓谦; 王坤正

    2015-01-01

    目的 验证髌骨周围去神经化是否能改善保留髌骨的初次全膝关节置换术后.方法 本研究通过检索MEDLINE、EMBASE、PubMed、SpringerLink、Web of Knowledge、OVID CINAHL、OV-ID EBM等数据库,筛选2014年1月之前发表的文献.应用meta分析方法评价髌骨去神经化对于保留髌骨的全膝关节置换术后膝前痛及膝关节功能的影响,以说明去神经化在全膝关节置换术中的作用.结果 本研究共纳入8篇随机对照文献,总病例数为1 048例,其中去神经化组526例,对照组(未去神经化组)522例.Meta分析结果表明髌骨周围去神经化对保留髌骨的全膝关节置换术后膝前痛的发生率(P=0.18)及VAS评分(P=0.23)差异均无统计学意义.然而,Patellar评分(P=0.01)、WOMAC评分(P<0.01)及术后膝关节活动范围(ROM)(P<0.01)均显示髌骨去神经化可以明显改善保留髌骨的全膝关节置换术后膝关节功能.结论 虽然髌骨去神经化没有明显改善保留髌骨的全膝关节置换术后膝前痛的发生,但是可以明显改善术后膝关节功能.因此笔者认为保留髌骨的全膝关节置换术中髌骨周围去神经化的处理可以明显改善患者术后.%Objective To identify and assess whether circumferential electrocautery is useful to improve outcomes after primary total knee replacement.Methods We searched MEDLINE,EMBASE,PubMed,SpringerLink,Web of Knowledge,OVID CINAHL,OVID EBM and Google Scholar,and included articles published through January 2014.This study used the methods of meta-analysis to assess whether circumferential electrocautery could improve anterior knee pain and knee function after total knee replacement,and identified the function of circumferential electrocautery in total knee replacement.Results A total of eight articles met the inclusion criteria.Among the 1 048 cases included in the analysis,526 cases had patellar denervation,and 522 cases were in the control group.The meta-analysis revealed

  5. Acetogenic microbial degradation of vinyl chloride

    Science.gov (United States)

    Bradley, P.M.; Chapelle, F.H.

    2000-01-01

    Under methanogenic conditions, microbial degradation of [1,2-14C]vinyl chloride (VC) resulted in significant (14 ?? 3% maximum recovery) but transient recovery of radioactivity as 14C-acetate. Subsequently, 14C- acetate was degraded to 14CH4 and 14CO2 (18 ?? 2% and 54 ?? 3% final recoveries, respectively). In contrast, under 2-bromoethanesulfonic acid (BES) amended conditions, 14C-acetate recovery remained high (27 ?? 1% maximum recovery) throughout the study, no 14CH4 was produced, and the final recovery of 14CO2 was only 35 ?? 4%. These results demonstrate that oxidative acetogenesis may be an important mechanism for anaerobic VC biodegradation. Moreover, these results (1) demonstrate that microbial degradation of VC to CH4 and CO2 may involve oxidative acetogenesis followed by acetotrophic methanogenesis and (2) suggest that oxidative acetogenesis may be the initial step in the net oxidation of VC to CO2 reported previously under Fe(III)-reducing, SO4-reducing, and humic acids- reducing conditions.Under methanogenic conditions, microbial degradation of [1,2-14C]vinyl chloride (VC) resulted in significant (14 ?? 3% maximum recovery) but transient recovery of radioactivity as 14C-acetate. Subsequently, 14C-acetate was degraded to 14CH4 and 14CO2 (18 ?? 2% and 54 ?? 3% final recoveries respectively). In contrast, under 2-bromoethanesulfonic acid (BES) amended conditions, 14C-acetate recovery remained high (27 ?? 1% maximum recovery) throughout the study, no 14CH4 was produced, and the final recovery of 14CO2 was only 35 ?? 4%. These results demonstrate that oxidative acetogenesis may be an important mechanism for anaerobic VC biodegradation. Moreover, these results (1) demonstrate that microbial degradation of VC to CH4 and CO2 may involve oxidative acetogenesis followed by acetotrophic methanogenesis and (2) suggest that oxidative acetogenesis may be the initial step in the net oxidation of VC to CO2 reported previously under Fe(III)-reducing, SO4-reducing, and

  6. Biotic degradation at night, abiotic degradation at day: positive feedbacks on litter decomposition in drylands.

    Science.gov (United States)

    Gliksman, Daniel; Rey, Ana; Seligmann, Ron; Dumbur, Rita; Sperling, Or; Navon, Yael; Haenel, Sabine; De Angelis, Paolo; Arnone, John A; Grünzweig, José M

    2017-04-01

    The arid and semi-arid drylands of the world are increasingly recognized for their role in the terrestrial net carbon dioxide (CO2 ) uptake, which depends largely on plant litter decomposition and the subsequent release of CO2 back to the atmosphere. Observed decomposition rates in drylands are higher than predictions by biogeochemical models, which are traditionally based on microbial (biotic) degradation enabled by precipitation as the main mechanism of litter decomposition. Consequently, recent research in drylands has focused on abiotic mechanisms, mainly photochemical and thermal degradation, but they only partly explain litter decomposition under dry conditions, suggesting the operation of an additional mechanism. Here we show that in the absence of precipitation, absorption of dew and water vapor by litter in the field enables microbial degradation at night. By experimentally manipulating solar irradiance and nighttime air humidity, we estimated that most of the litter CO2 efflux and decay occurring in the dry season was due to nighttime microbial degradation, with considerable additional contributions from photochemical and thermal degradation during the daytime. In a complementary study, at three sites across the Mediterranean Basin, litter CO2 efflux was largely explained by litter moisture driving microbial degradation and ultraviolet radiation driving photodegradation. We further observed mutual enhancement of microbial activity and photodegradation at a daily scale. Identifying the interplay of decay mechanisms enhances our understanding of carbon turnover in drylands, which should improve the predictions of the long-term trend of global carbon sequestration.

  7. Engineering TCE-degrading rhizobacteria for heavy metal accumulation and enhanced TCE degradation.

    Science.gov (United States)

    Lee, Wonkyu; Wood, Thomas K; Chen, Wilfred

    2006-10-20

    Many superfund sites are currently co-contaminated with organic pollutants such as trichloroethene (TCE) and heavy metals. A promising strategy to address these mixed-waste situations is the use of TCE-degrading rhizobacteria that will survive and thrive in soil heavily polluted with heavy metals. In this work, a gene coding for the metal-binding peptide, EC20, was introduced into rhizobacteria engineered for TCE degradation, resulting in strains with both metal accumulation and TCE degradation capabilities. EC20 was displayed onto the cell surface of Pseudomonas strain Pb2-1 and Rhizobium strain 10320D using an ice-nucleation protein (INP) anchor. Expression of EC20 was confirmed by Western blot analysis and cells with EC20 expression showed sixfold higher cadmium accumulation than non-engineered strains in the presence of 16 microM CdCl(2). As expected, the TCE degradation rate was reduced in the presence of cadmium for cells without EC20 expression. However, expression of EC20 (higher cadmium accumulation) completely restored the level of TCE degradation. These results demonstrated that EC20 expression enhanced not only cadmium accumulation but also reduced the toxic effect of cadmium on TCE degradation. We expect that similar improvements will be observed when these engineered rhizobacteria are inoculated onto plant roots.

  8. Hydroxyl radical induced degradation of ibuprofen.

    Science.gov (United States)

    Illés, Erzsébet; Takács, Erzsébet; Dombi, András; Gajda-Schrantz, Krisztina; Rácz, Gergely; Gonter, Katalin; Wojnárovits, László

    2013-03-01

    Pulse radiolysis experiments were used to characterize the intermediates formed from ibuprofen during electron beam irradiation in a solution of 0.1mmoldm(-3). For end product characterization (60)Co γ-irradiation was used and the samples were evaluated either by taking their UV-vis spectra or by HPLC with UV or MS detection. The reactions of OH resulted in hydroxycyclohexadienyl type radical intermediates. The intermediates produced in further reactions hydroxylated the derivatives of ibuprofen as final products. The hydrated electron attacked the carboxyl group. Ibuprofen degradation is more efficient under oxidative conditions than under reductive conditions. The ecotoxicity of the solution was monitored by Daphnia magna standard microbiotest and Vibrio fischeri luminescent bacteria test. The toxic effect of the aerated ibuprofen solution first increased upon irradiation indicating a higher toxicity of the first degradation products, then decreased with increasing absorbed dose.

  9. Degradation of polychlorinated naphthalene by mechanochemical treatment.

    Science.gov (United States)

    Nomura, Yugo; Aono, Sho; Arino, Takashi; Yamamoto, Takashi; Terada, Akihiko; Noma, Yukio; Hosomi, Masaaki

    2013-11-01

    Polychlorinated naphthalene (PCN) is a hazardous compound that is listed as a new persistent organic pollutants candidate by the United Nations Environment Program. The production, import and use of PCNs are prohibited by the Chemical Substances Control Law in Japan. PCN was milled with calcium oxide as an additive to investigate the feasibility of its degradation by mechanochemical treatment. The milling process cleaved the C-C and C-Cl bonds by the mechanically induced solid-state reaction. Gas chromatography/mass spectrometry analysis confirmed that the PCN was decomposed after 1h milling. The yield of chloride ions reached 100% after 3h milling. This indicates that all PCN was broken down into inorganic compounds after milling, thereby maintaining the chlorine mass balance through the reaction. This experiment, for the first time, exhibited the effectiveness of mechanochemical treatment as a PCN degradation method.

  10. The Integrated Assessment of Land Degradation

    Directory of Open Access Journals (Sweden)

    Luca Salvati

    Full Text Available This paper reviews recent findings on the complex field of land degradation (LD with focus on the Mediterranean Basin and Italy, in particular. The LD definition and assessment methods are examined in the light of the most important natural and human driving forces of the phenomenon, such as land use and climate changes.Various methodological issues are dealt with from multidisciplinary perspective with the aim of providing the ground for the development of integrated approaches: monitoring needs, assessment of costs, development of mitigation strategies, etc. Factors affecting land vulnerability to degradation are classified into bio-physical and socio-economic drivers with some examples of applications in Italy. The role of determinants such as agricultural development, population growth, and urban sprawl is recognised as important but still ambiguous and thus needs further studies. Based on these findings, policy responses aimed at mitigating LD and thus reducing desertification risk are discussed and methodological proposal are presented.

  11. On-Orbit Teflon FEP Degradation

    Science.gov (United States)

    Townsend, Jacqueline A.; Hansen, Patricia A.; Dever, Joyce A.

    1998-01-01

    During the Hubble Space Telescope (HST) Second Servicing Mission (SM2), degradation of unsupported Teflon' FEP (fluorinated ethylene propylene), used as the outer layer of the multi-layer insulation (MLI) blankets, was evident as large cracks on the telescope light shield. A sample of the degraded outer layer was retrieved during the mission and returned to Earth for ground testing and evaluation. The results of the Teflon FEP sample evaluation and additional testing of pristine Teflon FEP led the investigative team to theorize that the HST damage was caused by thermal cycling with deep-layer damage from electron and proton radiation which allowed the propagation of cracks along stress concentrations, and that the damage increased with the combined total dose of electrons, protons, LTV and x-rays along with thermal cycling. This paper discusses the testing and evaluation of the Teflon FEP.

  12. Investigation of degradation mechanisms in composite matrices

    Science.gov (United States)

    Giori, C.; Yamauchi, T.

    1982-01-01

    Degradation mechanisms were investigated for graphite/polysulfone and graphite/epoxy laminates exposed to ultraviolet and high-energy electron radiations in vacuum up to 960 equivalent sun hours and 10 to the ninth power rads respectively. Based on GC and combined GC/MS analysis of volatile by-products evolved during irradiation, several free radical mechanisms of composite degradation were identified. The radiation resistance of different matrices was compared in terms of G values and quantum yields for gas formation. All the composite materials evaluated show high electron radiation stability and relatively low ultraviolet stability as indicated by low G values and high quantum for gas formation. Mechanical property measurements of irradiated samples did not reveal significant changes, with the possible exception of UV exposed polysulfone laminates. Hydrogen and methane were identified as the main by-products of irradiation, along with unexpectedly high levels of CO and CO2.

  13. Genetic Analysis of Nitroaromatic Degradation by Clostridium

    Science.gov (United States)

    2013-07-30

    overexpression strain didn’t improve the TNT degradation rate over that of wild type. Methyl viologen is another well known redox mediator. However... cellulose ) but also consider the community population which may include those organisms which form molecules that can act as e-carrier competitors to...associated proteins cyclopropane fatty acid synthase that is induced when cells enter stationary phase and are not making hydrogen, heavy metal proteins

  14. Pectinases in leaf degradation by aquatic Hyphomycetes

    OpenAIRE

    Chamier, Anne-Carole

    1980-01-01

    Packs of oak and alder leaves were submerged in late autumn in the River Bourne, a moderately eutrophic stream in Surrey so that the colonization pattern of aquatic Hyphomycetes on the leaves could be quantified as the leaves were degraded. The physico-chemical of the water was monitored over the experimental period and the inoculum available for leaf colonization was measured by filter counts of conidia in the stream. Colonization of the leaves by pectolytic bacteria was also measured. There...

  15. Bacterial Degradation of DNT and TNT Mixtures

    Science.gov (United States)

    2005-10-31

    hydroxylating dioxygenase and salicylate hydroxylase genes from JS180. Figure III-5. Conversion of 3M4NC to HNOHA by DniB. Figure III-6. Extradiol ring...cycloisomerases (tautomerases) from various lower pathways and fumarylacetoacetate (FAA) hydrolases from the phenylalanine /tyrosine degradation pathway...the salicylate hydroxylase from the naphthalene pathway, are functional (labeled G and H in Figure III- 3). Although the dioxygenase from JS180

  16. Alfalfa stem tissues: Cell wall deposition, composition, and degradability

    NARCIS (Netherlands)

    Jung, H.G.; Engels, F.M.

    2002-01-01

    Declining cell wall degradability of alfalfa (Medicago sativa L.) stems with maturation limits the nutritional value of alfalfa for ruminants. This study characterized changes in cell wall concentration, composition, and degradability by rumen microbes resulting from alfalfa stem tissue proliferatio

  17. THERMOSTABLE ALGINATE DEGRADING ENZYMES AND THEIR METHODS OF USE

    NARCIS (Netherlands)

    Hreggvidsson, Gudmundur Oli; Jonsson, Oskar W.J.; Bjornsdottir, Bryndis; Fridjonsson, Hedinn O; Altenbuchner, Josef; Watzlawick, Hildegard; Dobruchowska, Justyna; Kamerling, Johannis

    2015-01-01

    The present invention relates to the identification, production and use of thermostable alginate lyase enzymes that can be used to partially degrade alginate to yield oligosaccharides or to give complete degradation of alginate to yield (unsaturated) mono-uronates.

  18. Initial microbial degradation of polycyclic aromatic hydrocarbons

    Directory of Open Access Journals (Sweden)

    Milić Jelena

    2016-01-01

    Full Text Available The group of polycyclic aromatic hydrocarbons (PAHs are very hazardous environmental pollutants because of their mutagenic, carcinogenic and toxic effects on living systems. The aim of this study was to examine and compare the ability and efficiency of selected bacterial isolates obtained from oil-contaminated areas to biodegrade PAHs. The potential of the bacteria to biodegrade various aromatic hydrocarbons was assessed using the 2,6-dichlorophenol-indophenol assay. Further biodegradation of PAHs was monitored by gravimetric and gas-chromatographic analysis. Among the eight bacterial isolates, identified on the basis of 16S rDNA sequences, two isolates, Planomicrobium sp. RNP01 and Rhodococcus sp. RNP05, had the ability to grow on and utilize almost all examined hydrocarbons. Those isolates were further examined for biodegradation of phenanthrene and pyrene, as single substrates, and as a mixture, in vitro for ten days. After three days, both isolates degraded a significant amount phenanthrene, which has a simpler chemical structure than pyrene. Planomicrobium sp.RNP01 commenced biodegradation of pyrene in the PAH mixture only after it had almost completly degraded phenanthrene. The isolated and characterized bacteria, Planomicrobium sp. RNP01 and Rhodococcus sp. RNP05, have shown high bioremediation potential and are likely candidates to be used for degradation of highly toxic PAHs in contaminated areas. [Projekat Ministarstva nauke Republike Srbije, br. III43004

  19. Degradation of various dyes using Laccase enzyme.

    Science.gov (United States)

    Dhaarani, S; Priya, A K; Rajan, T Vel; Kartic, D Navamani

    2012-10-01

    Disposal of untreated dyeing effluent in water bodies, from textile industries, cause serious environmental and health hazards. The chemical structures of dye molecules are designed to resist fading on exposure to light or chemical attack, and they prove to be quite resistant towards microbial degradation. Therefore, current conventional biological processes may not be able to meet wastewater discharge criteria and reuse. An enzymatic treatment undergoes oxidative cleavage avoiding formation of toxic amines. Laccase is a multi-copper containing protein that catalyzes the oxidation of a wide range of aromatic substrates concomitantly with the reduction of molecular oxygen to water. UV visible spectral analysis of various synthetic dyes was performed in the study and wavelengths of maximum absorbance determined. Laccase enzyme was obtained from the fungi Pleorotus ostreatus. The enzyme showed high efficiency against Malachite Green, Basic Red and Acid Majanta with decolorization capacities of 97%, 94% and 94% respectively. Further, these dyes can be used for optimization of degradation parameters and analysis of degradation products.

  20. Electrochemical degradation and mineralization of glyphosate herbicide.

    Science.gov (United States)

    Tran, Nam; Drogui, Patrick; Doan, Tuan Linh; Le, Thanh Son; Nguyen, Hoai Chau

    2017-01-23

    The presence of herbicide is a concern for both human and ecological health. Glyphosate is occasionally detected as water contaminants in agriculture areas where the herbicide is used extensively. The removal of glyphosate in synthetic solution using advanced oxidation process is a possible approach for remediation of contaminated waters. The ability of electrochemical oxidation for the degradation and mineralization of glyphosate herbicide was investigated using Ti/PbO2 anode. The current intensity, treatment time, initial concentration and pH of solution are the influent parameters on the degradation efficiency. An experimental design methodology was applied to determine the optimal condition (in terms of cost/effectiveness) based on response surface methodology. Glyphosate concentration (C0 = 16.9 mg L(-1)) decreased up to 0.6 mg L(-1) when the optimal conditions were imposed (current intensity of 4.77A and treatment time of 173 min). The removal efficiencies of glyphosate and total organic carbon were 95 ±16% and 90.31%, respectively. This work demonstrates that electrochemical oxidation is a promising process for degradation and mineralization of glyphosate.

  1. Degradation of household biowaste in reactors.

    Science.gov (United States)

    Krzystek, L; Ledakowicz, S; Kahle, H J; Kaczorek, K

    2001-12-28

    Household derived biowaste was degraded by biological methods. The system involves the combined method of low-solids (up to 10% w/v of total solids (TS)) anaerobic digestion and aerobic degradation for the recovery of energy (biogas) and the production of fine humus-like material which can be used as a soil amender or a substrate for further thermal treatment (pyrolysis, gasification). The performance of batch and continuous processes carried out in bioreactors (stirred tank reactor, air-lift) of working volume 6 and 18 dm(3), at different temperatures (25-42 degrees C) was monitored by reduction of TS, volatile solids, chemical oxygen demand, total organic carbon, C/N in time. The application of continuous process with recirculation (33%) caused that for residence time of 8-16 h the obtained degree of organic load reduction was similar to that obtained after 72-96 h of the batch process. The experimental data of batch aerobic degradation was also subjected to kinetic analysis. The sequence of the two processes: aerobic and anaerobic or anaerobic and aerobic showed that the degree of organic load reduction was similar in both cases, while the amount of produced biogas was four times higher when the first stage was anaerobic. The final product after dewatering was subjected to pyrolysis and gasification. The gases obtained were characterised by a high heat of combustion of about 11-15 MJ Nm(-3).

  2. Soiling and degradation analysis of solar mirrors

    Science.gov (United States)

    Delord, Christine; Blaise, Anthony; Fernandez-García, Aránzazu; Martínez-Arcos, Lucía; Sutter, Florian; Reche-Navarro, Tomás Jesús

    2016-05-01

    The degradation and the soiling of the mirrors are dependent of the solar field and the mirrors technologies, the local climate, the meteorological events, the O&M tasks and the human activities around the site. In the frame of the European project SFERA II, the SODAM project has been the opportunity to compare the soiling and the degradation mechanisms on a Fresnel solar field installed in the South of France and on a parabolic-through solar field installed in the South of Spain. The analysis of the soiling has shown equivalent maximum weekly reflectance loss due to soiling in both sites but a double mean weekly reflectance loss in Spain respect to France, as well as typical meteorological events to be taken into account to adapt the cleaning strategies. Among the meteorological parameters mainly influencing the soiling, the study has revealed the effect of the rain and of the DNI. In parallel, the analysis of the degradation mechanisms has highlighted a common chalking of the protective back paint layers due to the irradiation. This chalking being associated to a leaching of the paint layers in the site of Cadarache due to the high presence of liquid water. A difference in the speed of corrosion of the silver layer has been also noticed, leading to a difference in the mechanisms of delamination of the paints layers.

  3. Degradation of Refuse in Hybrid Bioreactor Landfill

    Institute of Scientific and Technical Information of China (English)

    YAN LONG; Yu-YANG LONG; HAI-CHUN LIU; DONG-SHENG SHEN

    2009-01-01

    Objectivess To explore the process of refuse decomposition in hybrid bioreactor landfill. Methods The bioreactor landfill was operated in sequencing of facultative-anaerobic and aerobic conditions with leachate recireulation, pH, COD, and ammonia in the leachate and pH, biodegradable organic matter (BDM), and cation exchange capacity (CEC) in refuse were detected. Results CEC increased gradually with the degradation of refuse, which was negatively correlad, With BDM. COD and ammonia in the leachate was declined to 399.2 mg L-1 and 20.6 mg N L-1, respectively, during the 357-day operation. The respective concentrations of ammonia and COD were below the second and the third levels of current discharge standards in China. Conclusion The refuse is relatively stable at the end of hybrid bioreactor landfill operation. Most of the readily biodegradable organic matter is mineralized in the initial phase of refuse degradation, whereas the hard-biodegradable organic matter is mainly humidified in the maturity phase of refuse degradation.

  4. Chemical Warfare Agent Degradation and Decontamination

    Energy Technology Data Exchange (ETDEWEB)

    Talmage, Sylvia Smith [ORNL; Watson, Annetta Paule [ORNL; Hauschild, Veronique [U.S. Environmental Protection Agency; Munro, Nancy B [ORNL; King, J. [U.S. Army Environmental Center

    2007-02-01

    The decontamination of chemical warfare agents (CWA) from structures, environmental media, and even personnel has become an area of particular interest in recent years due to increased homeland security concerns. In addition to terrorist attacks, scenarios such as accidental releases of CWA from U.S. stockpile sites or from historic, buried munitions are also subjects for response planning. To facilitate rapid identification of practical and effective decontamination approaches, this paper reviews pathways of CWA degradation by natural means as well as those resulting from deliberately applied solutions and technologies; these pathways and technologies are compared and contrasted. We then review various technologies, both traditional and recent, with some emphasis on decontamination materials used for surfaces that are difficult to clean. Discussion is limited to the major threat CWA, namely sulfur mustard (HD, bis(2-chloroethyl)sulfide), VX (O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothioate), and the G-series nerve agents. The principal G-agents are GA (tabun, ethyl N,N-dimethylphosphoramidocyanidate), GB (sarin, isopropyl methylphosphonofluoridate), and GD (soman, pinacolyl methylphosphonofluoridate). The chemical decontamination pathways of each agent are outlined, with some discussion of intermediate and final degradation product toxicity. In all cases, and regardless of the CWA degradation pathway chosen for decontamination, it will be necessary to collect and analyze pertinent environmental samples during the treatment phase to confirm attainment of clearance levels.

  5. Glutaraldehyde degradation in hospital wastewater by photoozonation.

    Science.gov (United States)

    Kist, Lourdes Teresinha; Rosa, Ellen Caroline; Machado, Enio Leandro; Camargo, Maria Emilia; Moro, Celso Camilo

    2013-01-01

    In this paper, we assessed aqueous solutions of glutaraldehyde (GA), a chemical used for the disinfection of hospital materials, using advanced oxidative processes, O3, and UV, and the combination of the latter two. Assays with different ozone concentrations at distinct pH levels were conducted to determine the best treatment process. GA concentrations before and after each treatment were measured by spectrophotometry. The best treatment was that which combined O3 and UV, yielding a degradation of 72.0-75.0% in relation to the initial concentration with pH between 4 and 9. Kinetics demonstrated that GA degradation is not dependent on pH, as there was a first-order reaction with a rate constant of k = 0.0180 min(-1) for initial pH 9 and of k = 0.0179 min(-1) for initial pH 7, that is, the values are virtually the same. Secondary wastewater samples were also analysed using the septic tank/filter system of a regional hospital in Vale do Rio Pardo, state of Rio Grande do Sul, southern Brazil. In this case, the characteristics of the wastewater were described and, after treatment, a GA degradation rate of 23.3% was noted, with reductions of 75% for chemical oxygen demand, 81% for biochemical oxygen demand, 68% for turbidity, 70% for surfactants and total disinfection in terms of thermotolerant coliforms.

  6. Kinetics of alkali-based photocathode degradation

    Science.gov (United States)

    Pavlenko, Vitaly; Liu, Fangze; Hoffbauer, Mark A.; Moody, Nathan A.; Batista, Enrique R.

    2016-11-01

    We report on a kinetic model that describes the degradation of the quantum efficiency (QE) of Cs3Sb and negative electron affinity (NEA) GaAs photocathodes under UHV conditions. In addition to the generally accepted irreversible chemical change of a photocathode's surface due to reactions with residual gases, such as O2, CO2, and H2O, the model incorporates an intermediate reversible physisorption step, similar to Langmuir adsorption. This intermediate step is needed to satisfactorily describe the strongly non-exponential QE degradation curves for two distinctly different classes of photocathodes -surface-activated and "bulk," indicating that in both systems the QE degradation results from surface damage. The recovery of the QE upon improvement of vacuum conditions is also accurately predicted by this model with three parameters (rates of gas adsorption, desorption, and irreversible chemical reaction with the surface) comprising metrics to better characterize the lifetime of the cathodes, instead of time-pressure exposure expressed in Langmuir units.

  7. Kinetics of alkali-based photocathode degradation

    Directory of Open Access Journals (Sweden)

    Vitaly Pavlenko

    2016-11-01

    Full Text Available We report on a kinetic model that describes the degradation of the quantum efficiency (QE of Cs3Sb and negative electron affinity (NEA GaAs photocathodes under UHV conditions. In addition to the generally accepted irreversible chemical change of a photocathode’s surface due to reactions with residual gases, such as O2, CO2, and H2O, the model incorporates an intermediate reversible physisorption step, similar to Langmuir adsorption. This intermediate step is needed to satisfactorily describe the strongly non-exponential QE degradation curves for two distinctly different classes of photocathodes –surface-activated and “bulk,” indicating that in both systems the QE degradation results from surface damage. The recovery of the QE upon improvement of vacuum conditions is also accurately predicted by this model with three parameters (rates of gas adsorption, desorption, and irreversible chemical reaction with the surface comprising metrics to better characterize the lifetime of the cathodes, instead of time-pressure exposure expressed in Langmuir units.

  8. Photo, thermal and chemical degradation of riboflavin

    Directory of Open Access Journals (Sweden)

    Muhammad Ali Sheraz

    2014-08-01

    Full Text Available Riboflavin (RF, also known as vitamin B2, belongs to the class of water-soluble vitamins and is widely present in a variety of food products. It is sensitive to light and high temperature, and therefore, needs a consideration of these factors for its stability in food products and pharmaceutical preparations. A number of other factors have also been identified that affect the stability of RF. These factors include radiation source, its intensity and wavelength, pH, presence of oxygen, buffer concentration and ionic strength, solvent polarity and viscosity, and use of stabilizers and complexing agents. A detailed review of the literature in this field has been made and all those factors that affect the photo, thermal and chemical degradation of RF have been discussed. RF undergoes degradation through several mechanisms and an understanding of the mode of photo- and thermal degradation of RF may help in the stabilization of the vitamin. A general scheme for the photodegradation of RF is presented.

  9. Enantioselective Degradation of Triadimefon in Green-house Soil

    Directory of Open Access Journals (Sweden)

    Liu Hong Cheng

    2015-09-01

    Full Text Available To study enantioselctive degradation of triadimefon, the enantioselective degradation of triadimefon in greenhouse soil and normal soil were investigated in detail. The enantiomers of triadimefon were separated by Chiralpak AD column and determined by Liquid Chromatography Via Tandem Mass Spectrometry (LC-MS/MS. The degradation exhibited some enantioselective, resulting in a concentration order of R-(- tridimefon>S-(+ triadimefon and the degradation of triadimefon in greenhouse soils with high content of organic matter was faster than normal soil.

  10. The Degradational History of Endeavour Crater, Mars

    Science.gov (United States)

    Grant, J. A.; Parker, T. J.; Crumpler, L. S.; Wilson, S. A.; Golombek, M. P.; Mittlefehldt, D. W.

    2015-01-01

    Endeavour crater (2.28 deg S, 354.77 deg E) is a Noachian-aged 22 km-diameter impact structure of complex morphology in Meridiani Planum. The degradation state of the crater has been studied using Mars Reconnaissance Orbiter and Opportunity rover data. Exposed rim segments rise approximately 10 m to approximately 100 m above the level of the embaying Burns Formation and the crater is 200-500 m deep with the southern interior wall exposing over approximately 300 m relief. Both pre-impact rocks (Matijevic Formation) and Endeavour impact ejecta (Shoemaker Formation) are present at Cape York, but only the Shoemaker crops out (up to approximately 140 m) along the rim segment from Murray Ridge to Cape Tribulation. Study of pristine complex craters Bopolu and Tooting, and morphometry of other martian complex craters, enables us to approximate Endeavour's pristine form. The original rim likely averaged 410 m (+/-)200 m in elevation and a 250-275 m section of ejecta ((+/-)50-60 m) would have composed a significant fraction of the rim height. The original crater depth was likely between 1.5 km and 2.2 km. Comparison between the predicted original and current form of Endeavour suggests approximately 100-200 m rim lowering that removed most ejecta in some locales (e.g., Cape York) while thick sections remain elsewhere (e.g., Cape Tribulation). Almost complete removal of ejecta at Cape York and minimal observable offset across fractures indicates current differences in rim relief are not solely due to original rim relief. Rim segments are embayed by approximately 100-200 m thickness of plains rocks outside the crater, but thicker deposits lie inside the crater. Ventifact textures confirm ongoing eolian erosion with the overall extent difficult to estimate. Analogy with degraded Noachian-aged craters south of Endeavour, however, suggests fluvial erosion dominated rim degradation in the Noachian and was likely followed by approximately 10s of meters modification by alternate

  11. THE FTIR STUDIES OF PHOTO-OXIDATIVE DEGRADATION OF POLYPROPYLENE

    Institute of Scientific and Technical Information of China (English)

    WEN Zaiqing; HU Xingzhou; SHEN Deyan

    1988-01-01

    The photo-oxidative degradation process of polypropylene film containing iron ions was investigated via FTIR and absorbance substraction technique. It is shown that the iron ions play an important role in the decomposition of hydroperoxide and the increase of the degradation rate of polypropylene film. Theamorphous region of PP film undergoes degradation prior to the crystalline one.

  12. Non-destructive Techniques for Classifying Aircraft Coating Degradation

    Science.gov (United States)

    2015-03-26

    of coating degradation creates a significant cost to the Air Force in both time and money. In this research infrared spectra were examined as... Degradation . . . . . . . . . . . . . . . . . . . . . 5 2.2 Fourier Transform Infrared Spectroscopy...From previous results it is expected that long-wave infrared reflectance measurement will perform the best in determining coating degradation and so

  13. Degradation of organic nitrogenous wastes by a soil streptomycete.

    Science.gov (United States)

    De, S; Chandra, A L

    1979-01-01

    A soil streptomycete degraded hair, silk, wool, feather and leather which were collected from solid wastes. The organism was identified taxonomically and designated Streptomyces sp. A956. It degraded leather to the maximum extent and solubilized 35.9% of the total nitrogen, 2.32 mg of glycine equivalent amino nitrogen could be obtained by degradation of 100 mg leather.

  14. A Novel Electrocatalysis Method for Organic Pollutants Degradation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A novel electrocatalysis, ferrous ion catalyzed anodic-cathodic electrocatalysis (FACEC), was developed for organic pollutants degradation, which could promote the degradation by achieving synergetic effects of both anodic oxidation and cathodic indirect oxidation. The degradation rate of model pollutants - phenol by FACEC could increase by nearly 30% comparing with that of anodic electrocatalysis, and the current efficiency could reach 67%.

  15. Degradation of the organic phase of bone by osteoclasts

    DEFF Research Database (Denmark)

    Henriksen, Kim; Sørensen, Mette G; Nielsen, Rasmus H

    2006-01-01

    Osteoclasts degrade bone matrix by secretion of hydrochloric acid and proteases. We studied the processes involved in the degradation of the organic matrix of bone in detail and found that lysosomal acidification is involved in this process and that MMPs are capable of degrading the organic matri...

  16. Degradation of Chlorinated Aromatic Compounds in UASB Reactors

    DEFF Research Database (Denmark)

    Christiansen, Nina; Hendriksen, Hanne Vang; Järvinen, Kimmo T.;

    1995-01-01

    Data on anaerobic degradation of chloroaromatic compounds in Upflow Anaerobic Sludge Blanket Reactors (UASB-reactor) are presented and compared. Special attention is given to the metabolic pathways for degradation of chlorinated phenols by granular sludge. Results indicate that PCP can be degraded...

  17. Method Designed To Detect Alginate-Degrading Bacteria

    OpenAIRE

    Kitamikado, Manabu; Yamaguchi, Kuniko; Tseng, Chao-Huang; Okabe, Bun'Ichi

    1990-01-01

    A simple turbidimetric method was developed to detect alginate degradation. Bacteria were grown in alginate-containing media, and culture fluids were mixed with an acidic albumin solution. Failure to develop a white turbidity indicated an alginate degrader. The method showed alginate degradation by Vibrio alginolyticus ATCC 17749, in contrast to prior descriptions.

  18. Characterization of degraded soils in the humid Ethiopian highlands

    NARCIS (Netherlands)

    Tebebu, Tigist Y.; Bayabil, Haimanote K.; Stoof, C.R.; Giri, Shree K.; Gessess, A.A.; Tilahun, Seifu A.; Steenhuis, Tammo S.

    2016-01-01

    Hard pan is a major cause of land degradation that affects agricultural productivity in developing countries. However, relatively little is known about the interaction of land degradation and hardpans. The objective of this study was, therefore, to investigate soil degradation and the formation of h

  19. Solvent effects on the AIBN forced degradation of cumene: Implications for forced degradation practices.

    Science.gov (United States)

    Nelson, Eric D; Thompson, Gina M; Yao, Ye; Flanagan, Holly M; Harmon, Paul A

    2009-03-01

    Solvent effects on the AIBN and ACVA forced degradation of cumene are explored. The degradant formation rates of the three cumene oxidative degradants, cumene hydroperoxide, acetophenone, and 2-phenyl-2-propanol are reported. The relative abundance and ratios of these three degradants provide insight into the fate of the peroxy radical oxidants generated by the forced stress system, and suggest that alkoxy radicals are actually a significant source of the observed reactivity. The presence of even 1% methanol in the forced stress solvent significantly quenches this alkoxy radical reactivity, dramatically reducing the overall degradation rate and leaving cumene hydroperoxide as the major product of the oxidation reaction. The origin of this significant solvent effect on the oxidation product distribution is shown to be related to the preferential H-atom abstraction from methanol and its trace impurities by any alkoxy radicals present in the reaction solution. The implications for these observations are explored with the intent of producing more predictive oxidative forced stress experiments.

  20. [Photocatalytic degradation of acetamiprid by TiO2 and Xe lamp: kinetics and degradation intermediates].

    Science.gov (United States)

    Zhou, Wen-Chang; Yang, Hai; Hu, Zhi-Bin; Lan, Shi-Lin

    2014-12-01

    Photocatalytic degradation kinetics of acetamiprid was studied by both of single-variable-at-a-time (SVAT) and central composite design (CCD) experiments based on four factors, such as catalyst dosages, substrate concentration, temperature and pH values. The results indicated that degradation of acetamiprid followed pseudo first-order kinetics by Langmuir-Hinshelwood model, increased with the increasing of temperature and the decreasing of substrate concentration. The photocatalytic degradation kinetic rate of acetamiprid was low in acid solutions, while high in weak acidic and alkaline solutions. After studying the synergistic effects of these four classic parameters, the optimal experiment conditions for photocatalytic degradation of acetamiprid were obtained as follows: TiO2 at 2.30 g x L(-1), initial acetamiprid concentration of 90.0 μmol x L(-1), temperature of 37.5 degrees C and pH value at 5.0. Lastly, 7 degradation intermediates of acetamiprid were detected during photocatalytic process by HPLC, and 6 of them exhibited more polar than the parent molecule.

  1. [Isolation and identification of degradation bacteria Enterobacter aerogenes for pyrethriods pesticide residues and its degradation characteristics].

    Science.gov (United States)

    Liao, Min; Zhang, Hai-jun; Xie, Xiao-mei

    2009-08-15

    By incubation experiment, the bacterial strain labeled as M6R9 was isolated from the tame sludge in water course of Pesticide Factory of Hangzhou, and was identified as Enterobacter aerogenes, which had highly efficient degradation for Bifenthrin, Fenpropathrin and Cypermethrin. By investigating the physiological characteristics of the strain, the results show that the bacterium is a gram-negative aerobe bacilli, size is (0.8-1.9) microm x (0.5-1.0) microm, and is capable of utilizing Bifenthrin, Fenpropathrin and Cypermethrin as sole carbon source. Under the condition of ventilation, (25-30) degrees C, inoculated amount at D(415 nm) 0.2, pH 7.0, pesticide concentration 100 mg x L(-1) and vibrational speed 180 r x min(-1), the degradation efficiencies to Bifenthrin, Fenpropathrin and Cypermethrin are the highest by strain M6R9. Under such condition, in the mixture culture medium with 100 mg x L(-1) Bifenthrin, Fenpropathrin and Cypermethrin, the degradation ratios are 55.74%, 55.11% and 55.96% after culturing 3 d, respectively, the degradation processes are fitted for first-order kinetic equation and the half lives (t(1/2)) are 65.4,70.7 and 68.6 h respectively. The degradation ability of Enterobacter aerogenes M6R9 on Bifenthrin, Fenpropathrin and Cypermethrin is positively correlated to inoculated amount,vibrational speed and ventilation.

  2. [The degradation characteristics of degrading bacterium of 2,6-di-tert-butylphenol].

    Science.gov (United States)

    Fang, Zhen-wei; Xu, De-qiang; Zhang, Ya-lei; Xiao, Yi-ping; Zhao, Jian-fu

    2004-05-01

    A degrading bacterial strain F-3-4 for 2,6-Di-tert-butylphenol (2,6-DTBP) was isolated from biofilm in acrylic fiber wastewater treatment structures. By acclimation, its capacity for degradation of 2,6-DTBP was enhanced by 26%. It was identified as Alcaligenes sp. according to morphological, physiological and biochemical characters. By tests in shaking flasks, the effects of the conditions of growth was studied, and it was determined that the optimum conditions of growth for the strain was 37 degrees C, pH 7.0 and inoculum amount 0.1%. Under these conditions, the kinetics of degradation for 2,6-DTBP of initial concentration 100 mg/L was studied, and the result indicated that the removal rate of 2,6-DTBP within 11 days was 62.4%, and the degradation process followed Eckenfelder kinetics. The half life of 2,6-DTBP was 9.38 days. The effect of initial concentration on degradation ability of the strain also was investigated. The results showed that the optimum initial concentration was 200 mg/L. When the initial concentrations were below it, the growth of strain and removal of 2,6-DTBP increased with the increase of initial concentration, while when above the value, they were inhibited.

  3. Degradation of phenazone in aqueous solution with ozone: influencing factors and degradation pathways.

    Science.gov (United States)

    Miao, Heng-Feng; Cao, Meng; Xu, Dan-Yao; Ren, Hong-Yan; Zhao, Ming-Xing; Huang, Zhen-Xing; Ruan, Wen-Quan

    2015-01-01

    Oxidation kinetics and degradation pathways of phenazone (an analgesic and antipyretic drug) upon reaction with O3 were investigated. Kinetic studies on degradation of phenazone were carried out under different operating conditions such as temperature, pH, anions and H2O2 addition. Results showed that the degradation followed the pseudo-first-order kinetic model. The reaction rate constant (kobs) of phenazone reached the maximum at 20 °C (9.653×10(-3) s(-1)). The presence of NO3(-) could enhance the degradation rate, while the addition of HCO3(-), SO4(2)(-), Cl(-) and the rise of pH showed negative effects on the ozonation of phenazone. H2O2 addition increased the phenazone degradation efficiency by 45.9% with the optimal concentration of 0.135 mM. Reaction by-products were evaluated by UPLC-Q-TOF-MS, which allowed the identification of a total of 10 by-products. The transformation pathways of phenazone ozonation consisted mainly of electrophilic addition and substitution, pyrazole ring opening, hydroxylation, dephenylization and coupling. The toxicity of these intermediate products showed that they are expected not to be more toxic than phenazone, with the exception of P7 (aniline) and P10 (1,5-dimethyl-4-((1-methyl-2-phenylhydrazinyl)methoxy)-2-phenyl-1H-pyrazol-3(2H)-one).

  4. Biosurfactant and Degradative Enzymes Mediated Crude Oil Degradation by Bacterium Bacillus subtilis A1

    Science.gov (United States)

    Parthipan, Punniyakotti; Preetham, Elumalai; Machuca, Laura L.; Rahman, Pattanathu K. S. M.; Murugan, Kadarkarai; Rajasekar, Aruliah

    2017-01-01

    In this work, the biodegradation of the crude oil by the potential biosurfactant producing Bacillus subtilis A1 was investigated. The isolate had the ability to synthesize degradative enzymes such as alkane hydroxylase and alcohol dehydrogenase at the time of biodegradation of hydrocarbon. The biosurfactant producing conditions were optimized as pH 7.0, temperature 40°C, 2% sucrose and 3% of yeast extract as best carbon and nitrogen sources for maximum production of biosurfactant (4.85 g l-1). Specifically, the low molecular weight compounds, i.e., C10–C14 were completely degraded, while C15–C19 were degraded up to 97% from the total hydrocarbon pools. Overall crude oil degradation efficiency of the strain A1 was about 87% within a short period of time (7 days). The accumulated biosurfactant from the biodegradation medium was characterized to be lipopeptide in nature. The strain A1 was found to be more robust than other reported biosurfactant producing bacteria in degradation efficiency of crude oil due to their enzyme production capability and therefore can be used to remove the hydrocarbon pollutants from contaminated environment. PMID:28232826

  5. High Modulus Biodegradable Polyurethanes for Vascular Stents: Evaluation of Accelerated in vitro Degradation and Cell Viability of Degradation Products.

    Science.gov (United States)

    Sgarioto, Melissa; Adhikari, Raju; Gunatillake, Pathiraja A; Moore, Tim; Patterson, John; Nagel, Marie-Danielle; Malherbe, François

    2015-01-01

    We have recently reported the mechanical properties and hydrolytic degradation behavior of a series of NovoSorb™ biodegradable polyurethanes (PUs) prepared by varying the hard segment (HS) weight percentage from 60 to 100. In this study, the in vitro degradation behavior of these PUs with and without extracellular matrix (ECM) coating was investigated under accelerated hydrolytic degradation (phosphate buffer saline; PBS/70°C) conditions. The mass loss at different time intervals and the effect of aqueous degradation products on the viability and growth of human umbilical vein endothelial cells (HUVEC) were examined. The results showed that PUs with HS 80% and below completely disintegrated leaving no visual polymer residue at 18 weeks and the degradation medium turned acidic due to the accumulation of products from the soft segment (SS) degradation. As expected the PU with the lowest HS was the fastest to degrade. The accumulated degradation products, when tested undiluted, showed viability of about 40% for HUVEC cells. However, the viability was over 80% when the solution was diluted to 50% and below. The growth of HUVEC cells is similar to but not identical to that observed with tissue culture polystyrene standard (TCPS). The results from this in vitro study suggested that the PUs in the series degraded primarily due to the SS degradation and the cell viability of the accumulated acidic degradation products showed poor viability to HUVEC cells when tested undiluted, however particles released to the degradation medium showed cell viability over 80%.

  6. ENHANCED DEGRADATION OF CAPTAN BY IMMOBILIZED CELLS OF BACILLUS CIRCULANS

    OpenAIRE

    Veena More; Preeti Tallur; More, Sunil S.; Niyonzima, Francois N.; Harichandra Ninnekar

    2014-01-01

    The possibility of using Bacillus circulans in degrading captan was evaluated by comparing the captan degradation rate by freely suspended and immobilized cells on agar, sodium alginate (SA), polyacrylamide (PA) and polyurethane-foam (PUF) in batch and repeated batch degradations. Under batch degradations, 50, 60, 72, and 88% of 0.1% captan was degraded by freely suspended cells, agar-, SA-, and PA-immobilized cells, respectively in 72 h; whereas 15, 47.5, 67.7 and 75% of 0.2% captan was degr...

  7. Bounds on the Effect of Progressive Structural Degradation

    DEFF Research Database (Denmark)

    Achtziger, Wolfgang; Bendsøe, Martin P; Taylor, John E.

    1997-01-01

    Problem formulations are presented for the evaluation of upper and lower bounds on the effect of progressive structural degradation. For the purposes of this study, degradation effect is measured by an increase in global structural compliance (flexibility). Thus the stated bounds are given simply...... by the maximum and minimum values, respectively, of the increase in compliance corresponding to a specified global interval of degradation. Solutions to these optimization problems identify the particular patterns of local degradation associated with the respective 'worst case' and 'least degrading...

  8. Photocatalytic degradation of methylene blue with a nanocomposite system: synthesis, photocatalysis and degradation pathways.

    Science.gov (United States)

    Xia, Shengjie; Zhang, Lianyang; Pan, Guoxiang; Qian, Pingping; Ni, Zheming

    2015-02-21

    Three different composites, including a calcined FeOOH supported ZnAl layered double hydroxide (FeOOH-LDO), a calcined ZnAl layered double hydroxide (ZnAl-LDO) and a calcined ZnFeAl layered double hydroxide (ZnFeAl-LDO), were synthesized via a sol-gel method, and their activity for the visible light photocatalytic degradation of methylene blue (MB) was studied. The composites were characterized by PXRD, SEM, and BET techniques, confirming the formation of highly crystalline structures. The activity performance of MB degradation was in the following order: FeOOH-LDO (∼95%) > ZnFeAl-LDO (∼60%) > ZnAl-LDO (∼23%). In addition, a possible photocatalytic degradation reaction mechanism for MB was also proposed. Moreover, the frontier electron densities on the atoms of MB were calculated, which were in satisfactory agreement with the postulated mechanism.

  9. Evaluation of the performance degradation at PAFC effect of catalyst degradation on electrode performance

    Energy Technology Data Exchange (ETDEWEB)

    Nishizaki, K.; Uchida, H.; Watanabe, M. [Yamanashi Univ., Kofu (Japan)] [and others

    1996-12-31

    Aiming commercialization of Phosphoric Acid Fuel Cell (PAFC) power plant, many researches and developments have been contributed. Over 20000 hours operations have been demonstrated by many PAFC power plants. But there is no effective method for the estimation of lifetime of electrochemical cells without a practical long-term operation. Conducted by New Energy and Industrial Technology Development Organization (NEDO), cooperative research projects aiming development of PAFC lifetime estimation method have started since 1995 FY in Japan. As part of this project, this work has been performed to clarify basic phenomena of the performance degradation at PAFCs jointly by Yamanashi University, Phosphoric Acid Fuel Cell Technology Research Association (PAFC-TRA) and PAFC manufacturers (Toshiba Co., Mitsubishi Electric Co, Fuji Electric Co.). Among several main causes of the cell performance degradation, effects of catalyst degradation (reduction in metal surface area, dealloying, changes in catalyst support) on PAFC cathode performances are discussed in this work.

  10. [Isolation of an anthracene-degrading strain Aspergillus fumigatus A10 and its degradation characteristics].

    Science.gov (United States)

    Qiang, Jing; Yin, Hua; Peng, Hui; Ye, Jin-Shao; Qin, Hua-Ming; He, Bao-Yan; Zhang, Na

    2009-05-15

    An anthracene-degrading strain (A10) was isolated from contaminated environment and identified as Aspergillus fumigatus. The experimental results showed that the biodegradation rate of anthracene increased with the increasing time. Between 12-84 h interval, the biodegradation performed rapidly, while after this, the increase of biodegradation rate tended to become slow, and ultimately the biodegradation rate could achieve approximately 83%. The degradatinn rate of anthracene reached 79.37% within 5 days when the initial concentration of anthracene in mineral salts medium (MSM) was 10 mg/L, the inoculum dosage was 50 g/L (wet weight) and the cell age was 36 h. The concentration of anthracene had notable influence on degradation function of strain A10 and the highest degradation rate (92.17%) was achieved when anthracene concentration was 5 mg/L. The degradation rate could maintain about 60% with initial pH of MSM in the range of 5.0-7.5, and also, the anthracene could be better broken down when the temperature was 30 degrees C and dissolved oxygen was 4.30 mg/L. Certain amount of nutrition salts promoted the biodegradation of anthracene to some extent. Addition of lactose as co-metabolic substrate most favorably accelerated degradation of anthracene by about 37.15%. The mechanism research revealed that the biodegradation by strain A10 was a dynamic process in which extracellular sorption and intracellular degradation were included. FT-IR analysis exhibited that the structure of anthracene changed with the action of microbe, generating a series of metabolites, such as aromatic acid, aromatic ketone, aromatic aldehyde with one or two benzene rings, as well as saturated hydrocarbons.

  11. Hydrolytic and oxidative degradation of electrospun supramolecular biomaterials: In vitro degradation pathways.

    Science.gov (United States)

    Brugmans, M C P; Sӧntjens, S H M; Cox, M A J; Nandakumar, A; Bosman, A W; Mes, T; Janssen, H M; Bouten, C V C; Baaijens, F P T; Driessen-Mol, A

    2015-11-01

    The emerging field of in situ tissue engineering (TE) of load bearing tissues places high demands on the implanted scaffolds, as these scaffolds should provide mechanical stability immediately upon implantation. The new class of synthetic supramolecular biomaterial polymers, which contain non-covalent interactions between the polymer chains, thereby forming complex 3D structures by self assembly. Here, we have aimed to map the degradation characteristics of promising (supramolecular) materials, by using a combination of in vitro tests. The selected biomaterials were all polycaprolactones (PCLs), either conventional and unmodified PCL, or PCL with supramolecular hydrogen bonding moieties (either 2-ureido-[1H]-pyrimidin-4-one or bis-urea units) incorporated into the backbone. As these materials are elastomeric, they are suitable candidates for cardiovascular TE applications. Electrospun scaffold strips of these materials were incubated with solutions containing enzymes that catalyze hydrolysis, or solutions containing oxidative species. At several time points, chemical, morphological, and mechanical properties were investigated. It was demonstrated that conventional and supramolecular PCL-based polymers respond differently to enzyme-accelerated hydrolytic or oxidative degradation, depending on the morphological and chemical composition of the material. Conventional PCL is more prone to hydrolytic enzymatic degradation as compared to the investigated supramolecular materials, while, in contrast, the latter materials are more susceptible to oxidative degradation. Given the observed degradation pathways of the examined materials, we are able to tailor degradation characteristics by combining selected PCL backbones with additional supramolecular moieties. The presented combination of in vitro test methods can be employed to screen, limit, and select biomaterials for pre-clinical in vivo studies targeted to different clinical applications.

  12. Degradation kinetics of ptaquiloside in soil and soil solution

    DEFF Research Database (Denmark)

    Ovesen, Rikke Gleerup; Rasmussen, Lars Holm; Hansen, Hans Christian Bruun

    2008-01-01

    Ptaquiloside (PTA) is a carcinogenic norsesquiterpene glycoside produced in bracken (Pteridium aquilinum (L.) Kuhn), a widespread, aggressive weed. Transfer of PTA to soil and soil solution eventually may contaminate groundwater and surface water. Degradation rates of PTA were quantified in soil...... and soil solutions in sandy and clayey soils subjected to high natural PTA loads from bracken stands. Degradation kinetics in moist soil could be fitted with the sum of a fast and a slow first-order reaction; the fast reaction contributed 20 to 50% of the total degradation of PTA. The fast reaction....... Experiments with sterile controls confirmed that nonmicrobial degradation processes constituted more than 90% of the fast degradation and 50% of the slow degradation. The lower nonmicrobial degradation rate observed in the clayey compared with the sandy soil is attributed to a stabilizing effect of PTA...

  13. Levodopa in Mucuna pruriens and its degradation

    Science.gov (United States)

    Pulikkalpura, Haridas; Kurup, Rajani; Mathew, Paravanparampil Jacob; Baby, Sabulal

    2015-06-01

    Mucuna pruriens is the best known natural source of L-dopa, the gold standard for treatment of Parkinsonism. M. pruriens varieties are protein rich supplements, and are used as food and fodder worldwide. Here, we report L-dopa contents in seeds of fifty six accessions of four M. pruriens varieties, M. pruriens var. pruriens, M. pruriens var. hirsuta, M. pruriens var. utilis and M. pruriens var. thekkadiensis, quantified by HPTLC-densitometry. L-dopa contents varied between 0.58 to 6.42 (%, dr. wt.). High and low L-dopa yielding genotypes/chemotypes of M. pruriens could be multiplied for medicinal and nutritional purposes, respectively. HPTLC profiles of M. pruriens seeds on repeated extraction (24 h) in 1:1 formic acid-alcohol followed by development in butanol:acetic acid:water (4:1:1, v/v) showed consistent degradation of L-dopa (Rf 0.34 ± 0.02) into a second peak (Rf 0.41 ± 0.02). An average of 52.11% degradation of L-dopa was found in seeds of M. pruriens varieties. Since M. pruriens seeds and/or L-dopa are used for treatment of Parkinson’s disease and as an aphrodisiac both in modern and/or traditional systems of medicine, the finding of high level of L-dopa degradation (in pure form and in M. pruriens extracts) into damaging quinones and ROS is very significant.

  14. Lignin degradation during plant litter photodegradation

    Science.gov (United States)

    Lin, Y.; King, J. Y.

    2014-12-01

    Lignin is the second most abundant compound, after cellulose, synthesized by plants. Numerous studies have demonstrated that initial lignin concentration is negatively correlated with litter decomposition rate under both laboratory and field conditions. Thus lignin is commonly considered to be a "recalcitrant" compound during litter decomposition. However, lignin can also serve as a radiation-absorbing compound during photodegradation, the process through which solar radiation breaks down organic matter. Here, we synthesize recent studies concerning lignin degradation during litter photodegradation and report results from our study on how photodegradation changes lignin chemistry at a molecular scale. Recent field studies have found that litter with high initial lignin concentration does not necessarily exhibit high mass loss during photodegradation. A meta-analysis (King et al. 2012) even found a weak negative correlation between initial lignin concentration and photodegradation rate. Contradicting results have been reported with regard to the change in lignin concentration during photodegradation. Some studies have found significant loss of lignin during photodegradation, while others have not. In most studies, loss of lignin only accounts for a small proportion of the overall mass loss. Using NMR spectroscopy, we found significant loss of lignin structural units containing beta-aryl ether linkages during photodegradation of a common grass litter, Bromus diandrus, even though conventional forage fiber analysis did not reveal changes in lignin concentration. Both our NMR and fiber analyses supported the idea that photodegradation induced loss of hemicellulose, which was mainly responsible for the litter mass loss during photodegradation. Our results suggest that photodegradation induces degradation, but not necessarily complete breakdown, of lignin structures and consequently exposes hemicellulose and cellulose to microbial decomposition. We conclude that lignin

  15. Poverty, population and environmental degradation in China.

    Science.gov (United States)

    Rozelle, S; Huang, J; Zhang, L

    1997-06-01

    This article examines the relationship between poverty, population, and environmental degradation in China. Environmental conditions include water pollution, deforestation, destruction of grasslands, soil erosion, and salinization. The authors review China's success in controlling environmental degradation through leadership, environmental policies, and institutional capacity. Findings suggest that environmental progress is best achieved indirectly by poverty alleviation, market integration, and population control. Government policies were not very effective. Degradation occurs due to limited financial resources, poorly trained personnel, and political factors. Control of water pollution was instituted since the 1980s. The levels of pollutants have been reduced, but the type of pollutant determines the seriousness of impact. Water pollution is due to industrial wastes, agricultural run-off, and soil erosion. Since the 1970s, reforestation targets have not been met. Technical extension and monitoring of planting is not available in most areas, and private, profit seeking interests control acreage. Grassland destruction is due to deforestation, agricultural expansion, and overgrazing. Independent regional authorities have successfully managed pasture programs. Erosion is the most serious in Loess Plateau, the Red Soils area, the Northeast China Plain, and the Northwest Grasslands, which comprise 70% of total land area. In 1990, erosion control was practiced in 39% of eroded land area. Salinization has remained fairly constant. Environmental controls (direct regulation, planned recovery, and state-mandated technological improvements) are uneven. The main tool for environmental management is the State Environmental Protection Commission and its executive unit, SEPA. Problems stem from vague laws, lack of means of enforcement, lack of coordination of laws, and lack of standards, schedules, and other provisions in ordinances.

  16. Endocannabinoid degradation, endotoxic shock and inflammation.

    Science.gov (United States)

    Maccarrone, M; Bari, M; Battista, N; Finazzi-Agrò, A

    2002-03-01

    Endocannabinoids are an emerging class of lipid mediators, which include amides and esters of long chain polyunsaturated fatty acids. Anandamide (N-arachidonoylethanolamine, AEA) and 2-arachidonoylglycerol (2-AG) are the main endogenous agonists of cannabinoid receptors. Endotoxic shock is a potentially lethal failure of multiple organs that can be initiated by the inflammatory agent lipopolysaccharide (LPS), present in the outer membrane of gram-negative bacteria. LPS has been recently shown to stimulate the production of AEA in rat macrophages, and of 2-AG in rat platelets. The mechanism responsible for this effect has not been elucidated. On the other hand, mast cells are multifunctional bone marrow-derived cells found in mucosal and connective tissues and in the nervous system, where they play an essential role in inflammation. As yet, little is known about endogenous modulators and mechanisms of mast cell activation. Here, we review recent literature on the role of endocannabinoids in endotoxic shock and inflammation, and report our recent research on the effects of LPS on the production of AEA and 2-AG in human lymphocytes, and on AEA degradation by a specific AEA membrane transporter (AMT) and an AEA-degrading enzyme (fatty acid amide hydrolase, FAAH). We also report the ability of the HMC-1 human mast cells to degrade AEA through a nitric oxide-sensitive AMT and a FAAH. The role of endocannabinoids in HMC-1 degranulation is discussed as well. Taken together, it can be suggested that human lymphocytes and mast cells take part in regulating the peripheral endocannabinoid system, which can affect some activities of these cells.

  17. Pre-heating mitigates composite degradation.

    Science.gov (United States)

    Silva, Jessika Calixto da; Rogério Vieira, Reges; Rege, Inara Carneiro Costa; Cruz, Carlos Alberto dos Santos; Vaz, Luís Geraldo; Estrela, Carlos; Castro, Fabrício Luscino Alves de

    2015-01-01

    Dental composites cured at high temperatures show improved properties and higher degrees of conversion; however, there is no information available about the effect of pre-heating on material degradation. Objectives This study evaluated the effect of pre-heating on the degradation of composites, based on the analysis of radiopacity and silver penetration using scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS). Material and Methods Thirty specimens were fabricated using a metallic matrix (2x8 mm) and the composites Durafill VS (Heraeus Kulzer), Z-250 (3M/ESPE), and Z-350 (3M/ESPE), cured at 25°C (no pre-heating) or 60°C (pre-heating). Specimens were stored sequentially in the following solutions: 1) water for 7 days (60°C), plus 0.1 N sodium hydroxide (NaOH) for 14 days (60°C); 2) 50% silver nitrate (AgNO3) for 10 days (60°C). Specimens were radiographed at baseline and after each storage time, and the images were evaluated in gray scale. After the storage protocol, samples were analyzed using SEM/EDS to check the depth of silver penetration. Radiopacity and silver penetration data were analyzed using ANOVA and Tukey's tests (α=5%). Results Radiopacity levels were as follows: Durafill VSZ-350>Z-250 (pheated specimens presented higher radiopacity values than non-pre-heated specimens (pheated specimens (pheating at 60°C mitigated the degradation of composites based on analysis of radiopacity and silver penetration depth.

  18. Properties and degradability of hydrothermal carbonization products.

    Science.gov (United States)

    Eibisch, Nina; Helfrich, Mirjam; Don, Axel; Mikutta, Robert; Kruse, Andrea; Ellerbrock, Ruth; Flessa, Heinz

    2013-09-01

    Biomass carbonized via hydrothermal carbonization (HTC) yields a liquid and a carbon (C)-rich solid called hydrochar. In soil, hydrochars may act as fertilizers and promote C sequestration. We assumed that the chemical composition of the raw material (woodchips, straw, grass cuttings, or digestate) determines the properties of the liquid and solid HTC products, including their degradability. Additionally, we investigated whether easily mineralizable organic components adsorbed on the hydrochar surface influence the degradability of the hydrochars and could be removed by repetitive washing. Carbon mineralization was measured as CO production over 30 d in aerobic incubation experiments with loamy sand. Chemical analysis revealed that most nutrients were preferably enriched in the liquid phase. The C mineralization of hydrochars from woodchips (2% of total C added), straw (3%), grass (6%), and digestate (14%) were dependent on the raw material carbonized and were significantly lower (by 60-92%; < 0.05) than the mineralization of the corresponding raw materials. Washing of the hydrochars significantly decreased mineralization of digestate-hydrochar (up to 40%) but had no effect on mineralization rates of the other three hydrochars. Variations in C mineralization between different hydrochars could be explained by multiple factors, including differences in the O/C-H/C ratios, C/N ratios, lignin content, amount of oxygen-containing functional groups, and pH. In contrast to the solids, the liquid products were highly degradable, with 61 to 89% of their dissolved organic C being mineralized within 30 d. The liquids may be treated aerobically (e.g., for nutrient recovery).

  19. CSNF WASTE FORM DEGRADATION: SUMMARY ABSTRACTION

    Energy Technology Data Exchange (ETDEWEB)

    J.C. CUNNANE

    2004-08-31

    The purpose of this model report is to describe the development and validation of models that can be used to calculate the release of radionuclides from commercial spent nuclear fuel (CSNF) following a hypothetical breach of the waste package and fuel cladding in the repository. The purpose also includes describing the uncertainties associated with modeling the radionuclide release for the range of CSNF types, exposure conditions, and durations for which the radionuclide release models are to be applied. This document was developed in accordance with Technical Work Plan for: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package (BSC 2004 [DIRS 169944]). This document considers radionuclides to be released from CSNF when they are available for mobilization by gas-phase mass transport, or by dissolution or colloid formation in water that may contact the fuel. Because other reports address limitations on the dissolved and colloidal radionuclide concentrations (BSC 2004 [DIRS 169944], Table 2-1), this report does not address processes that control the extent to which the radionuclides released from CSNF are mobilized and transported away from the fuel either in the gas phase or in the aqueous phase as dissolved and colloidal species. The scope is limited to consideration of degradation of the CSNF rods following an initial breach of the cladding. It considers features of CSNF that limit the availability of individual radionuclides for release into the gaseous or aqueous phases that may contact the fuel and the processes and events expected to degrade these CSNF features. In short, the purpose is to describe the characteristics of breached fuel rods and the degradation processes expected to influence radionuclide release.

  20. Microbial degradation of poly-beta-hydroxyalkanoates.

    Science.gov (United States)

    Mas-Castellà, J; Lafuente, R; Urmeneta, J; Goodwin, S; Guerrero, R

    1994-01-01

    The search for new materials that are not hazardous to the environment has become a major issue in our society, engaged as it is in the attainment of sustainable development. Poly-beta-hydroxyalkanoates (PHA), produced exclusively by prokaryotes, can be used as thermoplastics and are fully biodegradable and innocuous to the environment. Biodegradability testing has quantified the capacity of microorganisms to degrade such new chemical compounds, particularly polyhydroxyalkanoates. Standardized tests may also discover new microorganisms and environmental conditions that accelerate biodegradation. We evaluate various techniques used to assess the biodegradability of PHA, and which may also be applied to test other kinds of polymers.

  1. Service Degradation in Context Management Frameworks

    DEFF Research Database (Denmark)

    Shawky, Ahmed; Olsen, Rasmus Løvenstein; Pedersen, Jens Myrup

    2011-01-01

    Context aware network services are a new and inter-esting way to enhance network users experience. A context aware application/service enhances network performance in relation to dynamic context information, e.g. mobility, location and device information as it senses and reacts to environment...... changes. The reliability of the information accessed is a key factor in achieving reliable context aware application. This paper will review the service degradation in Context Management Frameworks (CMF) and the effect of high network utilization, with particular focus on the reliability of the accessed...

  2. The microbial degradation of azo dyes: minireview.

    Science.gov (United States)

    Chengalroyen, M D; Dabbs, E R

    2013-03-01

    The removal of dyes in wastewater treatment plants still involves physical or chemical processes. Yet numerous studies currently exist on degradation based on the use of microbes-which is a well-studied field. However progress in the use of biological methods to deal with this environmentally noxious waste is currently lacking. This review focuses on the largest dye class, that is azo dyes and their biodegradation. We summarize the bacteria identified thus far which have been implicated in dye decolorization and discuss the enzymes involved and mechanisms by which these colorants are broken down.

  3. Modelling degradation of bioresorbable polymeric medical devices

    CERN Document Server

    Pan, J

    2015-01-01

    The use of bioresorbable polymers in stents, fixation devices and tissue engineering is revolutionising medicine. Both industry and academic researchers are interested in using computer modelling to replace some experiments which are costly and time consuming. This book provides readers with a comprehensive review of modelling polymers and polymeric medical devices as an alternative to practical experiments. Chapters in part one provide readers with an overview of the fundamentals of biodegradation. Part two looks at a wide range of degradation theories for bioresorbable polymers and devices.

  4. Microbial degradation and utilization of cassava peel.

    Science.gov (United States)

    Ofuya, C O; Nwajiuba, C J

    1990-06-01

    Cassava peel was readily degraded and utilized by a strain ofRhizopus growing in a solid-state fermentation. Growth was maximal at 45°C and was proportional to the degree of hydrolysis of the peel. The yield of biomass, as weight of dry mycellum from the reducing sugars of the peel, was 51%. After 72 h fermentation, the peel contained 76% moisture, 6% cellulose, 7% hemicellulose and 0.4% ash and the protein content had increased from 5.6% to 16%. These results suggest a possible economic value of cassava peel in the production of fungal biomass and feedstock.

  5. Degradation of poplar bark by Panaeolus

    Energy Technology Data Exchange (ETDEWEB)

    Scurti, J.C.; Fiussello, N.; Gullino, M.L.; Ferrara, R.

    1978-01-01

    Pure cultures of 41 strains of Paneolus were tested for their ability to break down poplar bark with a view to their possible use for biodegradation of this waste product of paper manufacture. Most strains were able to grow (slowly) on sterilized poplar bark and showed high ligninolytic activity. Some strains also showed cellulolytic action. Almost all the strains showed phenol-oxidase activity, but there was no correlation between lignin decomposition and phenol-oxidase activity. The amounts of bark degraded by the fungi were relatively small (3.2 - 13.0% loss of dry weight after six months incubation).

  6. Effect of Circumferential Flow Non-uniformity on the Temperature Distribution of Membrane Water Wall in Supercritical Boilers and Simplified Calculation Methods%管内周向不均匀流动对超临界锅炉膜式水冷壁温度分布的影响及简化计算

    Institute of Scientific and Technical Information of China (English)

    李舟航; 唐国力; 吴玉新; 张海; 吕俊复

    2015-01-01

    Flow of supercritical water(SCW) is circumferentially non-uniform in the water wall of SCW boilers where heat is input on one side. To study the effect of inner flow non-uniformity(fluid temperature, heat transfer coefficient) on the temperature distribution of water wall, the SST k-ω turbulence model was employed to solve conjugate heat transfer between tube wall and SCW. After validating the model against experimental data, computational tests were performed in a membrane tube. Results show that circumferential non-uniformity has significant effect on wall temperature distribution in the region away from pseudocritical point, while this impact can be neglected within the pseudocritical region. Heat transfer coefficient at the midpoint of hot-side inner wall,αcp, is recommended to be adopted when one uses circumferential uniform assumption (T=Tb, α=αcp). Under this assumption, the position and value of maximum wall temperature can be accurately predicted in regions near and away from pseudocritical point. Besides, it is found that together with JB/Z201-83, Nusselt correlations based on uniformly-heated data can be used to predict the maximum wall temperature of membrane tube, with a deviation less than ±10K.%对于半周受热的超临界锅炉膜式水冷壁,管内工质温度和对流换热系数的周向分布具有较强的不均匀性。文中选取SST k-ω 湍流模型,在使用实验数据校验了模型后,对半周受热的鳍片管内超临界水的换热和通过管壁的导热进行耦合计算。计算结果表明在拟临界区外,工质温度和换热系数的周向不均匀性对壁温分布的影响很明显;在拟临界区内,周向不均匀性的影响则可忽略。采用周向均匀假设进行简化计算时,换热系数应该选取向火侧中点处的值,这样能保证在拟临界区内、外都能准确地预测向火侧的温度场以及危险点的位置和温度。此外,结果还表明可以使用基于全周

  7. Comparison of critical circumferential through-wall-crack-lengths in welds between pieces of straight pipes to welds between straigth pipes and bends with and without internal pressure at force- and displacement-controlled bending load; Vergleich kritischer Umfangsdurchrisslaengen in Schweissnaehten zwischen Geradrohrstuecken mit Schweissnaehten an Rohrbogen-Geradrohrverbindungen mit und ohne Innendruck bei kraft- und wegkontrollierter Biegebelastung

    Energy Technology Data Exchange (ETDEWEB)

    Steinbuch, R. [Fachhochschule fuer Technik und Wirtschaft Reutlingen (Germany). Fachbereich Maschinenbau

    1998-11-01

    Methods for calculation of critical, circumferential through-wall crack lengths in pipes have been developed and verified by several research projects. In applications during the last few years it has been found that the force or displacement-controlled loads have to be considered separately, and this approach was integrated into the recent methods. Methods so far assumed cracks to be located in welds joining straight pipes. But this approach starts from an incomplete picture of reality, as with today`s technology, circumferential welds are less frequent in straight pipes and much more frequent in pipework of other geometry, as for instance in welds joining straight pipes and bends, or bends with longer legs, nozzles, or T-pieces. The non-linear FEM parameter study presented in the paper, covering cases with internal pressure of pipes and one-dimensional bending loads, is based on current geometries of pipework in the primary and secondary loops of industrial plants and compares the conditions induced by circumferential through-wall cracks in welds joining only straight pipes and in those joining bended and straight pipes. At the relevant, displacement-controlled bending loads due to hampered thermal expansion of the pipe system, the critical through-wall cracks lengths occurring in pipe-to-bend welds are of about the same size and importance as those in pipe-to-pipe welds. As for the case of force-controlled loads, the technical codes calculate more serious effects and require lower bending load limits. Within the range of admissible loads given in the codes, the critical through-wall crack lengths occurring in pipe-to-bend welds are similar in size to those in straight pipe welds. It is therefore a conservative or realistic approach to apply the values determined for critical through-wall crack lengths in pipe-to-pipe joints also to pipe-to-bend welds. (orig./CB) [Deutsch] Verfahren zur Berechnung kritischer Umfangdurchrisslaengen in Rohrleitungen wurden in

  8. 外切内注辅助改良 PPH 术治疗环状混合痔的临床研究%External Excision and Internal Injection Sclerotherapy-Assisted Improved Procedure for Prolapsed Hemorrhoids for Circumferential Mixed Hemorrhoids

    Institute of Scientific and Technical Information of China (English)

    丛章龙; 武雅坤; 柳越冬

    2014-01-01

    目的:探讨外切内注辅助改良 PPH 术治疗环状混合痔的近期疗效。方法将符合环状混合痔纳入标准的142例患者按不同术式分为2组,治疗组(70例)采用外切内注辅助改良 PPH 术,对照组(72例)采用内扎内注外切术。观察2组病例术后24 h 疼痛程度、出血情况,术后第3天肛缘水肿、肛门坠胀、肛门狭窄和尿潴留等并发症发生情况。记录术后住院时间、恢复正常生活或工作时间。结果2组患者术后24 h 疼痛评分、出血情况、术后3 d肛门水肿、肛门坠胀及术后住院时间和恢复正常工作或生活时间差异有统计学意义(P <0.01),术后尿潴留发生率差异无统计学意义(P >0.05)。2组患者治愈率均为100%,术后近期均未发生肛门失禁、肛门狭窄及直肠阴道漏等严重并发症,远期疗效有待观察。结论外切内注辅助改良 PPH 在治疗环状混合痔疼痛程度轻,术后并发症少,恢复快,近期疗效优势明显。%Objective To explore the short-term effects of external excision and internal injec-tion sclerotherapy-assisted improved procedure for prolapsed hemorrhoids(PPH)on circumferen-tial mixed hemorrhoids.Methods A total of 142 patients with circumferential mixed hemorrhoids were divided into two groups.The treatment group(n=70)received external excision and internal injection sclerotherapy-assisted improved PPH.The control group(n=72)received internal liga-tion,internal injection sclerotherapy and external excision.The pain and bleeding were observed at 24 hours after operation.The anal margin edema,anal pendant expansion,anal stenosis,urinary retention and other complications were observed at 3 days after operation.In addition,the length of postoperative hospital stay and time to resuming to normal living or working were recorded. Results Pain score and bleeding at 24 hours after operation,anal margin edema and anal pendant expansion at 3

  9. Multiscale Concrete Modeling of Aging Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Hammi, Yousseff [Mississippi State Univ., Mississippi State, MS (United States); Gullett, Philipp [Mississippi State Univ., Mississippi State, MS (United States); Horstemeyer, Mark F. [Mississippi State Univ., Mississippi State, MS (United States)

    2015-07-31

    In this work a numerical finite element framework is implemented to enable the integration of coupled multiscale and multiphysics transport processes. A User Element subroutine (UEL) in Abaqus is used to simultaneously solve stress equilibrium, heat conduction, and multiple diffusion equations for 2D and 3D linear and quadratic elements. Transport processes in concrete structures and their degradation mechanisms are presented along with the discretization of the governing equations. The multiphysics modeling framework is theoretically extended to the linear elastic fracture mechanics (LEFM) by introducing the eXtended Finite Element Method (XFEM) and based on the XFEM user element implementation of Giner et al. [2009]. A damage model that takes into account the damage contribution from the different degradation mechanisms is theoretically developed. The total contribution of damage is forwarded to a Multi-Stage Fatigue (MSF) model to enable the assessment of the fatigue life and the deterioration of reinforced concrete structures in a nuclear power plant. Finally, two examples are presented to illustrate the developed multiphysics user element implementation and the XFEM implementation of Giner et al. [2009].

  10. Estuarine ecology of phenanthrene-degrading bacteria

    Science.gov (United States)

    Guerin, William F.; Jones, Galen E.

    1989-08-01

    Phenanthrene degrading bacteria were ubiquitously distributed in waters and sediments of the Great Bay Estuary, NH, as determined using a 14C-phenanthrene mineralization assay. Similar activities were observed in water samples collected in March and June when these were incubated at 18 °C even though ambient water temperatures were 1-4 °C and 10-22 °C, respectively. This observation indicated the constant presence of a mesophilic phenanthrene-degrading bacterial population in the estuary. Among water samples, the highest biodegradation activities were associated with samples collected downstream from a dredging operation which introduced high concentrations of coal tar PAH (polycyclic aromatic hydrocarbons) into the Cocheco River, and in areas receiving PAH from pleasure and commercial boating activities. Mid-estuarine maxima in biodegradation activity during both sampling trips suggested adaptation of the microbial flora to the salinities prevailing in the low turnover, high residence time portion of the Estuary at the time of sampling. Despite the hydrophobicity of phenanthrene, no correlation between biodegradation rates and particulate matter concentrations were observed. Similarly, concentrations of nutrients and dissolved and particulate organic matter correlated poorly with biodegradation rates. Better agreements between 14C-phenanthrene mineralization potentials and plate counts on a phenanthrene/toluene agar (PTA) medium were observed. Phenanthrene biodegradative activities and numbers of culturable bacteria growing on PTA were governed by the degree of previous exposure to PAH.

  11. Mechanical Properties of Degraded PMR-15 Resin

    Science.gov (United States)

    Tsuji, Luis C.

    2000-01-01

    Thermo-oxidative aging produces a nonuniform degradation state in PMR-15 resin. A surface layer, usually attributed to oxidative degradation, forms. This surface layer has different properties from the inner material. A set of material tests was designed to separate the properties of the oxidized surface layer from the properties of interior material. Test specimens were aged at 316 C in either air or nitrogen, for durations of up to 800 hr. The thickness of the oxidized surface layer in air aged specimens, and the shrinkage and coefficient of thermal expansion (CTE) of nitrogen aged specimens were measured directly. The nitrogen-aged specimens were assumed to have the same properties as the interior material in the air-aged specimens. Four-point-bend tests were performed to determine modulus of both the oxidized surface layer and the interior material. Bimaterial strip specimens consisting of oxidized surface material and unoxidized interior material were constructed and used to determine surface layer shrinkage and CTE. Results confirm that the surface layer and core materials have substantially different properties.

  12. Degradation of environmental pollutants by Trametes trogii.

    Science.gov (United States)

    Haglund, C; Levín, L; Forchiassin, F; López, M; Viale, A

    2002-01-01

    The ability of the ligninolytic fungus Trametes trogii to degrade in vitro different xenobiotics (PCBs, PAHs and dyes) was evaluated. Either 200 ppm of a PCB mixture (Aroclor 1150) or 160 ppm of an industrial PAH mixture (10% V/V of PAHs, principal components hexaethylbenzene, naphthalene, 1-methyl naphthalene, acenaphthylene, anthracene, fluorene and phenanthrene), were added to trophophasic and idiophasic cultures growing in a nitrogen limited mineral medium (glucose/asparagine) and in a complex medium (malt extract/glucose). Gas-liquid chromatography proved that within 7 to 12 d more than 90% of the organopollutants added were removed. The decrease in absorbance at 620 nm demonstrated that cultures of this fungus were able to transform 80% of the dye Anthraquinone-blue (added at a concentration of 50 ppm) in 1.5 h. Enzyme estimations indicated high activity of laccase (up to 0.55 U/mL), as well as lower production of manganese-peroxidase. Laccase activity, detected in all the conditions assayed, could be implicated in the degradation of these organopollutants. Considering the results obtained, T. trogii seems promising for detoxification.

  13. Photocatalytic degradation of synthetic dye under sunlight

    Directory of Open Access Journals (Sweden)

    Mijin Dušan

    2007-01-01

    Full Text Available Synthetic dyes are widely used in the textile industry. Dye pollutants from the textile industry are an important source of environmental contamination. The majority of these dyes are toxic, mostly non-biodegradable and also resistant to decomposition by physico-chemical methods. Among new oxidation methods or "advanced oxidation processes", heterogeneous photocatalysis appears as an emerging destructive technology leading to the total mineralization of many organic pollutants. CI Basic Yellow 28 (BY28, commonly used as a textile dye, could be photocatalytically degraded using TiU2 as catalyst under sunlight. The effect of some parameters such as the initial catalyst concentration, initial dye concentration, initial NaCl and Na2CO3 concentrations, pH, H2O2 and type of catalyst on the degradation rate of BY28 was examined in details. The presence of NaCl and Na2CO3 led to inhibition of the photodegradation process. The highest photodegradation rate was observed at high pH, while the rate was the lowest at low pH. Increase of the initial H2O2 concentration increased the initial BY28 photodegradation efficiency. ZnO was a better catalyst than TiO2 at low dye concentrations.

  14. Enhancement of Cellulose Degradation by Cattle Saliva.

    Science.gov (United States)

    Seki, Yasutaka; Kikuchi, Yukiko; Kimura, Yoshihiro; Yoshimoto, Ryo; Takahashi, Masatoshi; Aburai, Kenichi; Kanai, Yoshihiro; Ruike, Tatsushi; Iwabata, Kazuki; Sugawara, Fumio; Sakai, Hideki; Abe, Masahiko; Sakaguchi, Kengo

    2015-01-01

    Saccharification of cellulose is a promising technique for producing alternative source of energy. However, the efficiency of conversion of cellulose into soluble sugar using any currently available methodology is too low for industrial application. Many additives, such as surfactants, have been shown to enhance the efficiency of cellulose-to-sugar conversion. In this study, we have examined first whether cattle saliva, as an additive, would enhance the cellulase-catalyzed hydrolysis of cellulose, and subsequently elucidated the mechanism by which cattle saliva enhanced this conversion. Although cattle saliva, by itself, did not degrade cellulose, it enhanced the cellulase-catalyzed degradation of cellulose. Thus, the amount of reducing sugar produced increased approximately 2.9-fold by the addition of cattle saliva. We also found that non-enzymatic proteins, which were present in cattle saliva, were responsible for causing the enhancement effect. Third, the mechanism of cattle saliva mediated enhancement of cellulase activity was probably similar to that of the canonical surfactants. Cattle saliva is available in large amounts easily and cheaply, and it can be used without further purification. Thus, cattle saliva could be a promising additive for efficient saccharification of cellulose on an industrial scale.

  15. Advanced Cell Development and Degradation Studies

    Energy Technology Data Exchange (ETDEWEB)

    J. E. O' Brien; C. M. Stoots; J. S. Herring; R. C. O' Brien; K. G. Condie; M. Sohal; G. K. Housley; J. J. Hartvigsen; D. Larsen; G. Tao; B. Yildiz; V. Sharma; P. Singh; N. Petigny; T. L. Cable

    2010-09-01

    The Idaho National Laboratory (INL) has been researching the application of solid-oxide electrolysis cells for large-scale hydrogen production from steam over a temperature range of 800 to 900ºC. From 2003 – 2009, this work was sponsored by the DOE Nuclear Hydrogen Initiative (NHI). Starting in 2010, the HTE research program has been sponsored by the Next Generation Nuclear Plant (NGNP) program. HTSE research priorities in FY10 are centered on understanding and reducing cell and stack performance degradation to an acceptable level to advance the technology readiness level of HTSE and to justify further large-scale demonstration activities. This report provides a summary of our FY10 experimental program, which has been focused on advanced cell and stack development and degradation studies. Advanced cell and stack development activities are under way at five technology partners: MSRI, Versa Power, Ceramatec, NASA Glenn, and St. Gobain. Performance evaluation of the advanced technology cells and stacks has been performed by the technology partners, by MIT and the University of Connecticut and at the INL HTE Laboratory. Summaries of these development activities and test results are presented.

  16. Cubesat in-situ degradation detector (CIDD)

    Science.gov (United States)

    Rievers, Benny; Milke, Alexander; Salden, Daniel

    2015-07-01

    The design of the thermal control and management system (TCS) is a central task in satellite design. In order to evaluate and dimensionize the properties of the TCS, material parameters specifying the conductive and radiative properties of the different TCS components have to be known including their respective variations within the mission lifetime. In particular the thermo-optical properties of the outer surfaces including critical TCS components such as radiators and thermal insulation are subject to degradation caused by interaction with the space environment. The evaluation of these material parameters by means of ground testing is a time-consuming and expensive endeavor. Long-term in-situ measurements on board the ISS or large satellites not only realize a better implementation of the influence of the space environment but also imply high costs. Motivated by this we propose the utilization of low-cost nano-satellite systems to realize material tests within space at a considerably reduced cost. We present a nanosat-scale degradation sensor concept which realizes low power consumption and data rates compatible with nanosat boundaries at UHF radio. By means of a predefined measurement and messaging cycle temperature curves are measured and evaluated on ground to extract the change of absorptivity and emissivity over mission lifetime.

  17. Fungal Laccases Degradation of Endocrine Disrupting Compounds

    Directory of Open Access Journals (Sweden)

    Gemma Macellaro

    2014-01-01

    Full Text Available Over the past decades, water pollution by trace organic compounds (ng/L has become one of the key environmental issues in developed countries. This is the case of the emerging contaminants called endocrine disrupting compounds (EDCs. EDCs are a new class of environmental pollutants able to mimic or antagonize the effects of endogenous hormones, and are recently drawing scientific and public attention. Their widespread presence in the environment solicits the need of their removal from the contaminated sites. One promising approach to face this challenge consists in the use of enzymatic systems able to react with these molecules. Among the possible enzymes, oxidative enzymes are attracting increasing attention because of their versatility, the possibility to produce them on large scale, and to modify their properties. In this study five different EDCs were treated with four different fungal laccases, also in the presence of both synthetic and natural mediators. Mediators significantly increased the efficiency of the enzymatic treatment, promoting the degradation of substrates recalcitrant to laccase oxidation. The laccase showing the best performances was chosen to further investigate its oxidative capabilities against micropollutant mixtures. Improvement of enzyme performances in nonylphenol degradation rate was achieved through immobilization on glass beads.

  18. Glycidol degrades scrapie mouse prion protein.

    Science.gov (United States)

    Yamamoto, M; Horiuchi, M; Ishiguro, N; Shinagawa, M; Matsuo, T; Kaneko, K

    2001-09-01

    Agents of transmissible spongiform encephalopathy (prion) are known to be extremely resistant to physicochemical inactivation procedures such as heat, radiation, chemical disinfectants such as detergents, alcohols, glutaraldehyde, formalin, and so on. Because of its remarkable resistance, it is difficult to inactivate prion. Chemical inactivation seems to be a practical method because it is applicable to large or fixed surfaces and complicated equipment. Here, three epoxides: beta-propiolactone, propylene oxide, and glycidol (GLD) were examined of their inactivation ability against scrapie-mouse prion protein (PrP(Sc)) under various conditions of chemical concentration, incubation time, and temperature. Among these chemicals, GLD worked most effectively and degraded PrP into small fragments. As a result of the bioassay, treatment with 3% GLD for 5 hr and 5% GLD for 2, 5 hr or 12 hr at room temperature prolonged the mean incubation time by 44, 30, 110 and 73 days, respectively. From dose-incubation time standard curve, the decrease in infectivity titers were estimated as 10(3) or more. Therefore, degradation of PrP(Sc) by GLD decreased the scrapie infectivity. It is also suggested that pH and salt concentrations influence the effect of GLD. Although further study is necessary to determine the optimal condition, GLD may be a potential prion disinfectant.

  19. Biological degradation of chernozems under irrigation

    Directory of Open Access Journals (Sweden)

    Oksana Naydyonova

    2014-12-01

    Full Text Available We studied the changes in the state of microbial cenosis of Ukraine’s chernozems under irrigation. Considerable part of Ukraine’s chernozems is located in the areas where humidification is insufficient and unstable. Irrigation is a soil-reclamation measure for chernozems of Ukrainian Forest-steppe and Steppe which enables getting the assured yield, especially vegetable and fodder crops. At the same time, irrigation is a powerful anthropogenic factor that affects the soil, causes a significant transformation of many of its properties and regimes including biological ones. Often these changes are negative. The purpose of our investigation was to identify changes in the state of microbial cenoses of chernozem soils under irrigation which depend on such factors as the quality of irrigation water, the duration and intensity of irrigation, the initial properties of soil, the structure of crop rotation, usage of fertilizing systems and agroameliorative techniques. We identified direction and evaluated a degree of changes in biological properties of chernozems under influence of irrigation in different agro-irrigational and soil-climatic conditions. In the long-term stationary field experiments we identified the following biological indices of irrigated soils and their non-irrigated analogues: a number of microorganisms which belong to main ecological-trophic groups, activity of soil enzymes (dehydrogenase, invertase, phenol oxidase, soil phytotoxic activity, cellulose destroying capacity of soil, indices of oligotrophy and mineralization, summary biological index (SBI and index of biological degradation (BDI. Results of researches showed that irrigation unbalanced the soil ecosystem and stipulated the forming of microbial cenosis with new parameters. Long-term intensive irrigation of typical chernozem (Kharkiv Region with fresh water under condition of 4-fields vegetable crop rotation led to the degradation changes of its microbial cenosis such as

  20. Unveiling New Degradation Intermediates/Pathways from the Photocatalytic Degradation of Microcystin-LR

    Science.gov (United States)

    This study focuses on the identification of reaction intermediates formed during the photocatalytic degradation of the cyanotoxin microcystin-LR with immobilized TiO2 Tphotocatalysts at neutral pH. To differentiate between impurities already existing in the MC-LR stand...

  1. Spatial degradation mapping and componentwise degradation tracking in polymer-fullerene blends

    DEFF Research Database (Denmark)

    Pedersen, Emil Bøje Lind; Tromholt, Thomas; Madsen, Morten Vesterager;

    2014-01-01

    Using X-ray absorption the effects of photodegradation in active layer materials for polymer solar cells are investigated. Through the observation of changes in the X-ray absorption energy spectra the degradation of the individual components is tracked in blends of poly-3-hexyl-thiophene (P3HT...

  2. Microbial degradation of n-hexadecane in mineral salt medium as mediated by degradative enzymes.

    Science.gov (United States)

    Mishra, Shweta; Singh, S N

    2012-05-01

    In the present study, n-hexadecane degradation in MSM was investigated by three bacteria identified as Pseudomonas aeruginosa PSA5, Rhodococcus sp. NJ2 and Ochrobactrum intermedium P2, isolated from petroleum sludge. During 10 days of incubation, n-hexadecane was degraded to 99% by P. aeruginosa PSA5, 95% by Rhodococcus sp. NJ2 and 92% by O. intermedium P2. During degradation process, the induction of catabolic enzymes alkane hydroxylase, alcohol dehydrogenase and lipase were also examined. Among these enzymes, the highest activities of alkane hydroxylase (185 μmol mg(-1) protein) and alcohol dehydrogenase (75.78 μmol mg(-1) protein) were recorded in Rhodococcus sp. NJ2 while lipase activity was highly induced in P. aeruginosa PSA5 (48.71 μmol mg(-1) protein). Besides, accumulation of n-hexadecane in inclusion bodies was found to be maximum 60.8 g l(-1) in P. aeruginosa PSA5, followed by Rhodococcus sp. NJ2 (56.1 g l(-1)) and the least (51.6 g l(-1)) was found in O. intermedium P2. Biosurfactant production by bacterial strains was indicated by the reduction in surface tension and induction of cell surface hydrophobicity and pseudosolubilization which facilitated n-hexadecane degradation.

  3. Chromium related degradation of solid oxide fuel cells; Chrom-bezogene Degradation von Festoxid-Brennstoffzellen

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, Anita

    2011-05-04

    Solid Oxide Fuel Cells (SOFCs) offer a high potential for application as an auxiliary power unit (APU) for heavy goods vehicles as well as combined heat and power (CHP) systems. SOFCs are especially attractive due to their high efficiencies and the use of different fuel types. However, optimization in terms of long term stability and costs are still necessary. This work characterized the degradation of SOFCs with lanthanum strontium manganite (LSM) cathodes under chromium influence. Galvanostatic cell tests were carried out at 800 C with operation times from 250 - 3000 h and variation of the chromium source and current density. The current densities of j = 0 (A)/(cm{sup 2}), j = 0,3 (A)/(cm{sup 2}) and j = 0,5 (A)/(cm{sup 2}) were applied. The high temperature ferritic alloy Crofer22APU was used as a chromium source. Variation of the chromium source was realized by coating the Crofer22APU insert with the chromium retention layer Mn{sub 3}O{sub 4} and the cathode contact layer LCC10. Cell degradation was analyzed with regard to cell voltage, current density and area specific resistance (ASR). Microstructural alterations of the cathode as well as chromium content and distribution across the cell were investigated after completion of the cell tests. For cells with a chromium source present and operation with a nonzero current density, the course of cell degradation was divided into three phases: a run-in, weak linear degradation and strong linear degradation. A decrease of the chromium release rate by means of different coatings stretched the course of degradation along the timescale. Strong degradation, which is characterized by a significant increase in ASR as well as a decrease of current density at the operating point, was only observed when a chromium source in the setup was comb ined with operation of the cell with a non-zero current density. Operation of the cell with a chromium source but no current density caused a degradation of current density at the

  4. On differences between bathtub curves and linear degradation describing PV module degradation

    Science.gov (United States)

    von Roedern, Bolko

    2013-09-01

    This addresses two separate issues that the human mind often confuses. The first is that not all PV module degradation data is fully and accurately interpreted. Second is the assumption that full and accurate data interpretation will necessarily lead to deeper insight and more accurate future predictions. It is, however, not clear how much additional information can be gained from secondary signals (like luminescence) when they are "optimized." Often, these issues are reflected in data analyses that deal only with linear approximations., ignoring data that do not fit linear patterns. When claims are made that such data isn't public or does not exist with great enough accuracy, this may or may not reflect the real situation for making more accurate predictions. While it may be instructive to understand PV losses in terms of per year (annual) loss, it has to be realized that failure and degradation may be different if multiple degradation mechanisms are effective. A confusion may exists between average and individual numbers and greater accuracy and more data will not automatically guaranty deeper insight into an issue or allow more accurate future projections for an individual case. The issue is whether or not more insight is gained by separation to identify the largest mechanism, or whether the correct combination of features minimizes degradation mechanisms. The results of the author's personal home PV system (in its 7th year) are presented.

  5. 纵向、径向及周向二维应变评价冠心病患者左心室局部收缩功能异常%Longitudinal, radial and circumferential 2-dimensional strain for quantitative analysis of regional left ventricular systolic dysfunction in patients with coronary artery disease

    Institute of Scientific and Technical Information of China (English)

    李燕; 胡莉君; 李薇玢; 吕清; 王新房; 谢明星; 张静; 丁尚伟; 陈明; 王静; 贺林

    2009-01-01

    Objective To assess longitudinal, radial and circumferential systolic strain of regional myocardium in patients with coronary artery disease by 2-dimensional strain echocardiography, and to explore stenosis of coronary artery impacting on regional left ventricular systolic dysfunction in quietscent condition. Methods Twenty-six patients with coronary artery disease were entrolled into this study and 26 healthy volenteers in the control group. The two-dimensional loop-einec were obtained in apical 4-chamber view,apical 2-chamber view and long axis view of left venricular, and three levels of the short axis views (mitral valve,papillary muscle and cardiac apex). According to left ventricle 18 segments divla, there were 194 affected myocardiums in 26 cases. According to stenosis degrees of coronary artery, the affected myocardiums were divided into two groups: group A (coronary stenosis degree≤70%) and group B (coronary stenosis degree>70%). Longitudinal, radial and circumferential systolic strain (SL, SR, SC) from regional myocardium were analyzed. Results Group A had 90 segments. Compared with control group,SL was decreased significantly from control group (P 0.05). Group B had 104 segments. Compared with control group, SL, SC and SR were decreased significantly in group B(P 70%供血的心肌.结果 A组共90个节段.其纵向收缩期峰值应变(SL)明显低于对照组(P0.05);B组共104个节段,其SL、SR和SC均明显低于对照组(P<0.05),A组和B组之间SL、SC和SR的差异有统计学意义(P<0.05).结论 二维应变超声心动图能准确评价冠心病患者左室局部收缩功能异常,局部心肌SL、SR和SC的变化町反映冠脉狭窄严重程度.

  6. Photocatalytic Degradation of Diethyl Phthalate with Surfactant Addition

    Institute of Scientific and Technical Information of China (English)

    ZHANG Tianyong; HU Juan; ZHANG Youlan; LI Bin; FEI Xuening

    2006-01-01

    This paper studies the adsorption of diethyl phthalate (DEP,an environmental hormone) on the surface of nanoscale TiO2, effects of pH value of solutions, initial concentrations of DEP and additive surfactant on photocatalytic degradation and dynamics of DEP. Under ultra violet illumination, the interaction between DEP and surfactants including DBS (sodium dodecylbenzenesulfonate), CTAB (cetyltrimethylammonium bromide), and OP-10 (nonylphenol polyoxyethylene ether)was exploited from the perspective of degradation speed calculated by the data of high pressure liquid chromatography (HPLC) and UV-Vis spectra, respectively. Photocatalytic degradation of DEP followed pseudo first-order reaction kinetics. DEP as substrate degraded fast when its initial concentration was 130 mg/L. TiO2 had certain adsorption ability of DEP. TiO2 could adsorb the most DEP at the approximately neutral pH of 6.91. Degradation of DEP was not affected obviously by ad ditives OP-10 and JBS. Degradation rate of DEP was not enhanced greatly in the presence of surfactants, but degradation of DBS was sped up. Degradation rate of DEP was depressed in the presence of additive CTAB. The more CTAB was added, the less DEP was degraded. Degradation rate of CTAB became slow with the increase of initial CTAB concentration. The possible adsorption models among TiO2, DEP and surfactants were given.

  7. Degradation of Artemisinin-Based Combination Therapies Under Tropical Conditions.

    Science.gov (United States)

    Hall, Zoe; Allan, Elizabeth Louise; van Schalkwyk, Donelly Andrew; van Wyk, Albert; Kaur, Harparkash

    2016-05-01

    Poor quality antimalarials, including falsified, substandard, and degraded drugs, are a serious health concern in malaria-endemic countries. Guidelines are lacking on how to distinguish between substandard and degraded drugs. "Forced degradation" in an oven was carried out on three common artemisinin-based combination therapy (ACT) brands to detect products of degradation using liquid chromatography mass spectrometry and help facilitate classification of degraded drugs. "Natural aging" of 2,880 tablets each of ACTs artemether/lumefantrine and artesunate/amodiaquine was undertaken to evaluate their long-term stability in tropical climates. Samples were aged in the presence and absence of light on-site in Ghana and in a stability chamber (London), removed at regular intervals, and analyzed to determine loss of the active pharmaceutical ingredients (APIs) over time and detect products of degradation. Loss of APIs in naturally aged tablets (both in Ghana and the pharmaceutical stability chamber) was 0-7% over 3 years (∼12 months beyond expiry) with low levels of degradation products detected. Using this developed methodology, it was found that a quarter of ACTs purchased in Enugu, Nigeria (concurrent study), that would have been classified as substandard, were in fact degraded. Presence of degradation products together with evidence of insufficient APIs can be used to classify drugs as degraded.

  8. ENHANCED DEGRADATION OF CAPTAN BY IMMOBILIZED CELLS OF BACILLUS CIRCULANS

    Directory of Open Access Journals (Sweden)

    Veena More

    2014-10-01

    Full Text Available The possibility of using Bacillus circulans in degrading captan was evaluated by comparing the captan degradation rate by freely suspended and immobilized cells on agar, sodium alginate (SA, polyacrylamide (PA and polyurethane-foam (PUF in batch and repeated batch degradations. Under batch degradations, 50, 60, 72, and 88% of 0.1% captan was degraded by freely suspended cells, agar-, SA-, and PA-immobilized cells, respectively in 72 h; whereas 15, 47.5, 67.7 and 75% of 0.2% captan was degraded by freely suspended cells, agar-, SA-, and PA-immobilized cells, respectively in 72 h. However, 0.1 and 0.2% captan were completely degraded by PUF-immobilized cells in 48 and 72 h, respectively. Under repeated batch degradations, PUF-immobilized cells were reused more than 40 cycles for 72 h without losing the captan degradation ability, while the cells immobilized on agar, SA, and the PA could be reused for 15, 20, and 25 cycles, respectively. A significant 0.1% captan degradation by PUF-immobilized cells was observed at pH 4.0 - 10.0 and 20 - 40 ºC ranges. In contrast, freely suspended cells only degraded captan at optimum pH of 7.0 and 30 ºC. The PUF-immobilized cells were able to significantly degrade captan for 120 days at 4 ºC without losing the captan degradation ability; whereas this ability was lost in 120 days for freely suspended cells. Since the application of captan leads to pollution and reduces soil fertility, the use of immobilized cells of Bacillus circulans can thus be a better cost-effective strategy to decontaminate captan polluted sites.

  9. Degradation of glyphosate and other pesticides by ligninolytic enzymes.

    Science.gov (United States)

    Pizzul, Leticia; Castillo, María del Pilar; Stenström, John

    2009-11-01

    The ability of pure manganese peroxidase (MnP), laccase, lignin peroxidase (LiP) and horseradish peroxidase (HRP) to degrade the widely used herbicide glyphosate and other pesticides was studied in separate in vitro assays with addition of different mediators. Complete degradation of glyphosate was obtained with MnP, MnSO4 and Tween 80, with or without H2O2. In the presence of MnSO4, with or without H(2)O(2), MnP also transformed the herbicide, but to a lower rate. Laccase degraded glyphosate in the presence of (a) 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), (b) MnSO(4) and Tween 80 and (c) ABTS, MnSO4 and Tween 80. The metabolite AMPA was detected in all cases where degradation of glyphosate occurred and was not degraded. The LiP was tested alone or with MnSO4, Tween 80, veratryl alcohol or H2O2 and in the HRP assay the enzyme was added alone or with H2O2 in the reaction mixture. However, these enzymes did not degrade glyphosate. Further experiments using MnP together with MnSO4 and Tween 80 showed that the enzyme was also able to degrade glyphosate in its commercial formulation Roundup Bio. The same enzyme mixture was tested for degradation of 22 other pesticides and degradation products present in a mixture and all the compounds were transformed, with degradation percentages ranging between 20 and 100%. Our results highlight the potential of ligninolytic enzymes to degrade pesticides. Moreover, they suggest that the formation of AMPA, the main metabolite of glyphosate degradation found in soils, can be a result of the activity of lignin-degrading enzymes.

  10. Hydrolytic And Enzymatic Degradation Characteristics Of Biodegradable Aliphatic Polysters

    Institute of Scientific and Technical Information of China (English)

    LI Suming

    2004-01-01

    Aliphatic polyesters, especially those derived from lactide (PLA), glycolide (PGA) and ε-caprolactone (PCL), are being investigated worldwide for applications in the field of surgery (suture material, devices for internal bone fracture fixation), pharmacology (sustained drug delivery systems), and tissue engineering (scaffold for tissue regeneration) [1,2]. This is mainly due to their good biocompatibility and variable degradability. These polymers present also a growing interest for environmental applications in agriculture (mulch films) and in our everyday life (packaging material)as the development of biodegradable materials is now considered as one of the potential solutions to the problem of plastic waste management.For both biomedical and environmental applications, it is of major importance to understand the degradation characteristics of the polymers. The hydrolytic degradation of aliphatic polyesters has been investigated by many research groups. Our group has shown that degradation of PLAGA large size devices is faster inside than at the surface. This heterogeneous degradation is due to the autocatalytic effect of carboxylic endgroups formed by ester bond cleavage. Moreover,degradation-induced morphological and compositional changes were also elucidated. In the case of PCL, the hydrolytic degradation is very slow due to its hydrophobicity and crystallinity.The enzymatic degradation of these polymers has been investigated by a number of authors. A specific enzyme, proteinase K, has been shown to have significant effects on PLA degradation. This enzyme preferentially degrade L-lactate units as opposed to D-lactate ones, amorphous zones as opposed to crystalline ones [3]. The enzymatic degradation of PCL polymers has also been investigated. A number of lipase-type enzymes were found to significantly accelerate the degradation of PCL despite its high crystallinity. In the case of PLA/PCL blends, the two components exhibited well separated crystalline domains

  11. Mapping land degradation and desertification using remote sensing data

    Science.gov (United States)

    Saha, S. K.; Kumar, Munish; Lal, Bhajan; Barman, Alok Kumar; Das, Satyendra Nath

    2006-12-01

    Land degradation is the result of both natural and biotic forces operating on the earth. Natural calamities, over exploitation of land resources, unwise land use and the consequences of high inputs agriculture on soil and water resource are of great concern both at national and international level. It aggravated food insecurity in the world especially in the developing countries that calls for combating land degradation and desertification with scientific means. Development of degraded lands in India is one of the options to enhance food production and to restore the fragile ecosystem. The scientific information and spatial distribution of various kinds of degraded lands is thus essential for formulation of strategic plan to arrest the menace of land degradation. Remote sensing provides an opportunity for rapid inventorying of degraded lands to generate realistic database by virtue of multi-spectral and multi-temporal capabilities in the country. The satellite data provides subtle manifestations of degradation of land due to water and wind erosion, water-logging, salinity and alkalinity, shifting cultivation, etc., that facilitate mapping. All India Soil and Land Use Survey (AISLUS) has undertaken the task of land degradation mapping using remotely sensed data and developed a methodology accordingly. The mapping has been conceptualized as a four-tier approach comprising kind of degradation, severity of degradation, degradation under major landform and major land use. Visual mode of interpretation technique based on image characteristics followed by ground verification has been employed for mapping of degraded lands. Image interpretation key has been formulated based on the spectral signatures of various causative factors of different kinds of degraded lands. The mapping legend has been made systematic and connotative. The extent and spatial distribution of different kinds of degraded lands with degree of severity under major landform and major land use in a

  12. Practical vision based degraded text recognition system

    Science.gov (United States)

    Mohammad, Khader; Agaian, Sos; Saleh, Hani

    2011-02-01

    Rapid growth and progress in the medical, industrial, security and technology fields means more and more consideration for the use of camera based optical character recognition (OCR) Applying OCR to scanned documents is quite mature, and there are many commercial and research products available on this topic. These products achieve acceptable recognition accuracy and reasonable processing times especially with trained software, and constrained text characteristics. Even though the application space for OCR is huge, it is quite challenging to design a single system that is capable of performing automatic OCR for text embedded in an image irrespective of the application. Challenges for OCR systems include; images are taken under natural real world conditions, Surface curvature, text orientation, font, size, lighting conditions, and noise. These and many other conditions make it extremely difficult to achieve reasonable character recognition. Performance for conventional OCR systems drops dramatically as the degradation level of the text image quality increases. In this paper, a new recognition method is proposed to recognize solid or dotted line degraded characters. The degraded text string is localized and segmented using a new algorithm. The new method was implemented and tested using a development framework system that is capable of performing OCR on camera captured images. The framework allows parameter tuning of the image-processing algorithm based on a training set of camera-captured text images. Novel methods were used for enhancement, text localization and the segmentation algorithm which enables building a custom system that is capable of performing automatic OCR which can be used for different applications. The developed framework system includes: new image enhancement, filtering, and segmentation techniques which enabled higher recognition accuracies, faster processing time, and lower energy consumption, compared with the best state of the art published

  13. Praziquantel degradation in marine aquarium water

    Directory of Open Access Journals (Sweden)

    Amber Thomas

    2016-04-01

    Full Text Available Praziquantel (PZQ is a drug commonly utilized to treat both human schistosomiasis and some parasitic infections and infestations in animals. In the aquarium industry, PZQ can be administered in a “bath” to treat the presence of ectoparasites on both the gills and skin of fish and elasmobranchs. In order to fully treat an infestation, the bath treatment has to maintain therapeutic levels of PZQ over a period of days or weeks. It has long been assumed that, once administered, PZQ is stable in a marine environment throughout the treatment interval and must be mechanically removed, but no controlled experiments have been conducted to validate that claim. This study aimed to determine if PZQ would break down naturally within a marine aquarium below its 2 ppm therapeutic level during a typical 30-day treatment: and if so, does the presence of fish or the elimination of all living biological material impact the degradation of PZQ? Three 650 L marine aquarium systems, each containing 12 fish (French grunts: Haemulon flavolineatum, and three 650 L marine aquariums each containing no fish were treated with PZQ (2 ppm and concentrations were measured daily for 30 days. After one round of treatment, the PZQ was no longer detectable in any system after 8 (±1 days. The subsequent two PZQ treatments yielded even faster PZQ breakdown (non-detectable after 2 days and 2 ± 1 day, respectively with slight variations between systems. Linear mixed effects models of the data indicate that day and trial most impact PZQ degradation, while the presence of fish was not a factor in the best-fit models. In a completely sterilized marine system (0.5 L PZQ concentration remained unchanged over 15 days, suggesting that PZQ may be stable in a marine system during this time period. The degradation observed in non-sterile marine systems in this study may be microbial in nature. This work should be taken into consideration when providing PZQ bath treatments to marine animals

  14. Study on the Degradation of Polylactide Microsphere In Vitro

    Institute of Scientific and Technical Information of China (English)

    HeYing; WeiShuli

    2001-01-01

    This report concentrated on the rules and mechanism of the degradation of polylactide and the microspheres. The rate of degradation was assessed with five methods: observation of microsphere surface morphology by SEM, determination of the weight loss of the microspheres, determination of the molecular mass of the polymers by GPC, determination of pH and determination of the contents of lactic acid by UV spectrophotometry. The degradation of polylactide microspheres showed two-phase characteristics. At the early stage of the degradation, the high molecular mass polymers were cleaved into lower molecular mass fractions and at the late stage, there was a period of erosion and weight loss of the microspheres. The degradation was much slower for polymers with a higher molecular mass. The polylactide degradation showed good regularity.

  15. THE ROLE OF TRAFFIC IN THE DEGRADATION OF EARTH ROADS

    Directory of Open Access Journals (Sweden)

    BWEMBA CHARLES

    2011-10-01

    Full Text Available This article examines the contribution of traffic to earth road degradation. This study leads to degradation evolution laws based on the traffic factor.The Nkol-Afamba-Dzeng (earth road section of Divisional road 46 (D46 of the priority national road network was chosen as case study. Traffic and degradation census forms were designed and their exploitation on the field over a period of nine (9 months enabled the plotting of Degradation/Traffic curves.Various findings were interpreted, leading to the establishment of degradation laws. This study would be a useful tool for decision-makers who, in order to ensure timely maintenance,must consider the evolution of degradation and traffic on any given stretch of road.

  16. P-nitrophenol degradation by activated sludge attached on nonwovens.

    Science.gov (United States)

    Bhatti, Zafar Iqbal; Toda, Haruko; Furukawa, Kenji

    2002-03-01

    p-Nitrophenol (PNP) is a toxic compound that enters the environment during manufacturing and processing of a variety of industrial products. This study demonstrates the use of inexpensive and durable nonwovens as a biomass retainer for the biological degradation of p-nitrophenol. An essential aspect of p-nitrophenol degradation was the cultivation of p-nitrophenol degrading biomass prior to its attachment on the nonwovens. Results of continuous flow experiments demonstrated that using the nonwovens could attain consistent high-rate p-nitrophenol degradation. 500 mg-PNP/L was completely degraded at a hydraulic retention time of 11 h. Specific and volumetric p-nitrophenol loading rates were determined to be 165 mg-PNP/g-MLSS/d and 1.6 g-PNP/L/d, respectively. Nitrite released from p-nitrophenol breakdown was not completely nitrified to nitrate. Characteristics of p-nitrophenol degrading sludge were also investigated.

  17. Lactobacillus sps. lipase mediated poly (ε-caprolactone) degradation.

    Science.gov (United States)

    Khan, Imran; Ray Dutta, Jayati; Ganesan, Ramakrishnan

    2017-02-01

    Polymer degradation through lipase appears to be an enthralling alternative to bulk chemical routes. Poly (ε-caprolactone) (PCL) is an artificial polyester that can be degraded by microbes and enzymes like lipases and esterases. The environmental degradation of PCL is dependent on the activity of bacteria that characterization techniques such as thermogravimetric analysis, differential thermal are widely present in the ecosystem. In this study, three different lipases derived from Lactobacillus brevis, Lactobacillus plantarum and their co-culture have been utilized to explore their efficiency towards PCL enzymatic degradation. The effect of parameters such as enzyme loading and degradation time has been explored to understand the efficiency of the enzymes used in this study. Various analysis, scanning electron microscopy and Fourier transform infrared spectroscopy have been employed to study the enzymatic degradation and its possible mechanistic insight.

  18. Kinetics approach to modeling of polymer additive degradation in lubricants

    Institute of Scientific and Technical Information of China (English)

    llyaI.KUDISH; RubenG.AIRAPETYAN; Michael; J.; COVITCH

    2001-01-01

    A kinetics problem for a degrading polymer additive dissolved in a base stock is studied.The polymer degradation may be caused by the combination of such lubricant flow parameters aspressure, elongational strain rate, and temperature as well as lubricant viscosity and the polymercharacteristics (dissociation energy, bead radius, bond length, etc.). A fundamental approach tothe problem of modeling mechanically induced polymer degradation is proposed. The polymerdegradation is modeled on the basis of a kinetic equation for the density of the statistical distribu-tion of polymer molecules as a function of their molecular weight. The integrodifferential kineticequation for polymer degradation is solved numerically. The effects of pressure, elongational strainrate, temperature, and lubricant viscosity on the process of lubricant degradation are considered.The increase of pressure promotes fast degradation while the increase of temperature delaysdegradation. A comparison of a numerically calculated molecular weight distribution with an ex-perimental one obtained in bench tests showed that they are in excellent agreement with eachother.

  19. Degradation of nitrobenzene in wastewater by γ-ray irradiation

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shu-juan; FENG Shao-hong; YU Han-qing; LI Qian-rong

    2004-01-01

    The degradation of nitrobenzene(NB) by γ-ray irradiation was studied. The influences of dose rate and initial NB concentration were investigated in details. At a dose rate of 55 Gy/min, the degradation kinetics was pseudo-first-order at NB concentrations from 0.2 mmol/L to 4.0 mmol/L. At an initial NB concentration of 0.8 mmol/L, the degradation of NB at various dose rates also followed pseudo-first-order kinetics. Dissolved oxygen was found to have a positive effect on NB degradation. The degradation products were identified as nitrophenol, nitrosobenzene, and hydroquinone, and so on. Based on the product analysis, possible degradation pathways of nitrobenzene were proposed.

  20. [Characteristics and selectivity of photocatalytic-degradation of tetracycline hydrochloride].

    Science.gov (United States)

    Song, Chen-Yi; Yin, Da-Qiang

    2014-02-01

    The photocatalytic-degradation behavior of tetracycline hydrochloride (TTC) was studied. The catalyst used was photosensitive semiconductor titanium dioxide (TiO2). The results showed that the photocatalytic degradation of TTC was well fitted to first order reaction kinetics model, and the adsorption was the control step of the whole photocatalytic-degradation process, indicating that the main degradation path was the photocatalytic reaction of TTC adsorbed on the surface of TiO2. Besides, through photocatalytic-degradation of the mixed solution of TTC and sulfamethoxazole or amoxicillin, the degradation of the two antibiotics showed obvious selectivity when the pH, TiO2 dosage and other conditions were changed.