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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

    International Nuclear Information System (INIS)

    Roussel, G.

    1997-01-01

    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. ODSCC algorithm shows correlation with degradation

    International Nuclear Information System (INIS)

    Prabhu, P.J.; Rootham, M.W.; Zupetic, N.L.

    1998-01-01

    Over the last few years we have attempted to develop an algorithm to evaluate the impact of secondary water chemistry on tube degradation in PWR steam generators. Effects of individual factors were assessed and then consolidated to form an algorithm for ODSCC propensity. The algorithm utilizes secondary water chemistry data to calculate ODSCC propensity as a variable named Mega PHI. Prior attempts to correlate algorithm calculations with actual degradation in operating steam generators have resulted in very disappointing results. Recent modifications to the algorithm have demonstrated improved correlation between Mega PHI (calculated result from the algorithm) and actual degradation history from operating plants. The recent modifications involve the inclusion of the synergistic effect of boric acid application of secondary water and of high silica concentration in steam generator toward inhibiting ODSCC. Data from several plants with mill annealed alloy 600 tubing in the steam generators and operating with the primary coolant inlet temperature in the range of 608 to 624 degrees F (320 to 329 degrees C) were evaluated and the results compared with actual degradation reported from in-service inspections. The population of plants includes those with very few tubes repaired and those with hundreds of tubes repaired due to ODSCC at tube support plates. The observation of substantial correlation between the algorithm calculation and actual degradation signifies the roles of boric acid and silica in inhibiting ODSCC. It is recommended that further evaluation of the role of these chemical species be performed using more extensive data. The goal is to modify secondary water chemistry guidelines with the ultimate aim of minimizing corrosion of steam generator tubes. (author)

  3. Vogtle 1 - ODSCC

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, E.; O' Brien, T.; Leblanc, S.G.; Smith, T.; Mullins, R. [Southern Nuclear (United States)

    2011-07-01

    In the spring of 2008, refueling outage 1R14, Vogtle Electric Generating Plant Unit 1, a 4-loop Westinghouse PWR with Model F Steam Generators and thermally treated Alloy 600 tubes, performed tube pulls to confirm Outside Diameter Stress Corrosion Cracking (ODSCC) at the top of the tubesheet (TTS). During the previous outage, 1R13, Vogtle performed a planned full chemical cleaning of all steam generators. The 1R14 inspection showed a reduction in ODSCC from 1R13 which suggests a reduction in ODSCC initiation with respect to new degradation. At the time of the tube pull, Vogtle had been in-service for approximately 18.4 effective full power years, operated with 18 month fuel cycles, and had a hot leg temperature of 325 C (618 F). The inspections performed to detect this degradation were done with +Point at the TTS {+-} 3 inch (76 mm). The inspections and tube pull process were performed by Westinghouse Field Services. Similarly, respective laboratory analyses were performed by Westinghouse Chemistry Diagnostics and Materials Engineering, at the Science and Technology Center, Churchill, PA, U.S. In addition to examining the pulled tubes from Vogtle, archived tube samples were examined to compare grain structure and manufacturing process heat treatment effectiveness. (authors)

  4. Can we simulate the development of ODSCC defects in steam generator tubes?

    International Nuclear Information System (INIS)

    Cizelj, L.; Kovac, M.; Dvorsek, T.

    1999-01-01

    The qualitative and quantitative aspects of degradation mechanism causing early retirement of SG tubing are not yet explained to the level allowing for accurate predictions of future behavior. On the other hand, a large amount of data related to tube degradation, inspection, repair, and plant operation have been collected during recent years. It allows for reasonably accurate quantitative predictions, based on statistical analysis of past events and assumption of reasonably constant operating conditions. A computational algorithm was developed to simulate life cycle of ODSCC defects: initiation, growth, measurement, and repair. The main feature of the algorithm is the possibility to address some important changes in the operating parameters, especially those related to the conditions during the plant shutdown. The algorithm can be used to get better insight into the background of SG aging and to predict the future populations of defects, as shown in a realistic numerical example.(author)

  5. 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

  6. Automated analysis technique developed for detection of ODSCC on the tubes of OPR1000 steam generator

    International Nuclear Information System (INIS)

    Kim, In Chul; Nam, Min Woo

    2013-01-01

    A steam generator (SG) tube is an important component of a nuclear power plant (NPP). It works as a pressure boundary between the primary and secondary systems. The integrity of a SG tube can be assessed by an eddy current test every outage. The eddy current technique(adopting a bobbin probe) is currently the main technique used to assess the integrity of the tubing of a steam generator. An eddy current signal analyst for steam generator tubes continuously analyzes data over a given period of time. However, there are possibilities that the analyst conducting the test may get tired and cause mistakes, such as: missing indications or not being able to separate a true defect signal from one that is more complicated. This error could lead to confusion and an improper interpretation of the signal analysis. In order to avoid these possibilities, many countries of opted for automated analyses. Axial ODSCC (outside diameter stress corrosion cracking) defects on the tubes of OPR1000 steam generators have been found on the tube that are in contract with tube support plates. In this study, automated analysis software called CDS (computer data screening) made by Zetec was used. This paper will discuss the results of introducing an automated analysis system for an axial ODSCC on the tubes of an OPR1000 steam generator.

  7. Circumferential shaft seal

    Science.gov (United States)

    Ludwig, L. P. (Inventor)

    1981-01-01

    A circumferential shaft seal comprising two sealing rings held to a rotating shaft by means of a surrounding elastomeric band is disclosed. The rings are segmented and are of a rigid sealing material such as carbon or a polyimide and graphite fiber composite.

  8. Evaluation of ECT reliability for axial ODSCC in steam generator tubes

    International Nuclear Information System (INIS)

    Lee, Jae Bong; Park, Jai Hak; Kim, Hong Deok; Chung, Han Sub

    2010-01-01

    The integrity of steam generator tubes is usually evaluated based on eddy current test (ECT) results. Because detection capacity of the ECT is not perfect, all of the physical flaws, which actually exist in steam generator tubes, cannot be detected by ECT inspection. Therefore it is very important to analyze ECT reliability in the integrity assessment of steam generators. The reliability of an ECT inspection system is divided into reliability of inspection technique and reliability of quality of analyst. And the reliability of ECT results is also divided into reliability of size and reliability of detection. The reliability of ECT sizing is often characterized as a linear regression model relating true flaw size data to measured flaw size data. The reliability of detection is characterized in terms of probability of detection (POD), which is expressed as a function of flaw size. In this paper the reliability of an ECT inspection system is analyzed quantitatively. POD of the ECT inspection system for axial outside diameter stress corrosion cracks (ODSCC) in steam generator tubes is evaluated. Using a log-logistic regression model, POD is evaluated from hit (detection) and miss (no detection) binary data obtained from destructive and non-destructive inspections of cracked tubes. Crack length and crack depth are considered as variables in multivariate log-logistic regression and their effects on detection capacity are assessed using two-dimensional POD (2-D POD) surface. The reliability of detection is also analyzed using POD for inspection technique (POD T ) and POD for analyst (POD A ).

  9. Trends of degradation in steam generator tubes of Krsko NPP before the last planned inspection

    International Nuclear Information System (INIS)

    Cizelj, L.; Dvorsek, T.; Androjna, F.

    1998-01-01

    Full-length inspection of all active tubes in both Krsko steam generators resulted in a huge amount of inspection records. A computerized database was developed by Reactor Engineering division to accelerate the management of about 200.000 records. The database was designed to support the development and decision related to the plugging criteria for damaged tubes and is utilized to gain as much experience concerning the degradation of SG tube as possible. In this paper, two prevailing group of data are statistically analyzed: the axial cracks in expansion transitions at the top of tube sheet (TTS) and Outside Diameter Stress Corrosion Cracking at tube support plates (TSP). Especially ODSCC caused a vast majority of repaired tubes (e.g., plugs and sleeves). The influence of plant startups involving oxidizing transient on the repair rates of tubes affected by ODSCC is analyzed in some detail. The results are promising and show excellent correlation in SG 2 and reasonable fit in SG 1. Predictions of maximum expected number of tubes repaired due to ODSCC at the last planned inspection is given as 67 in SG 1 and 400 in SG 2. (author)

  10. Circumferential cracking of steam generator tubes

    International Nuclear Information System (INIS)

    Karwoski, K.J.

    1997-04-01

    On April 28, 1995, the U.S. Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 95-03, open-quote Circumferential Cracking of Steam Generator Tubes.close-quote GL 95-03 was issued to obtain information needed to verify licensee compliance with existing regulatory requirements regarding the integrity of steam generator tubes in domestic pressurized-water reactors (PWRs). This report briefly describes the design and function of domestic steam generators and summarizes the staff's assessment of the responses to GL 95-03. The report concludes with several observations related to steam generator operating experience. This report is intended to be representative of significant operating experience pertaining to circumferential cracking of steam generator tubes from April 1995 through December 1996. Operating experience prior to April 1995 is discussed throughout the report, as necessary, for completeness

  11. 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.

  12. Does circumferential tumor location affect the circumferential resection margin status in mid and low rectal cancer?

    Directory of Open Access Journals (Sweden)

    Byung Mo Kang

    2018-05-01

    Full Text Available Summary: Background/Objective: The purpose of this study was to assess the impact of circumferential tumor location on circumferential resection margin (CRM status and the depth of tumor invasion in mid and low rectal cancer. Methods: We retrospectively analyzed whole-mount slides of 58 patients who underwent total mesorectal excision for mid and low rectal cancer. The rate of tumor-positive CRM was compared according to the circumferential tumor location. In 31 patients, morphometric analyses of whole-mount specimens were performed to measure the depth of tumor invasion according to circumferential tumor location. Results: Among 58 patients, 50% of tumors were anterior tumor and 50% were nonanterior. A tumor-positive CRM was more observed frequently in anterior tumors than in nonanterior tumors (41.1% vs. 10.3%, p = 0.007. In a multivariate analysis, anterior tumor was the only independent risk factor for a positive CRM (odds ratio 4.725, 95% confidence interval 1.102–20.261, p = 0.037. In a morphometric analysis of 31 patients, the depth of tumor invasion from the muscularis mucosa was greater (11.9 mm vs. 6.6 mm, p = 0.028 in those with anterior tumors. Conclusion: Anterior tumors are associated with a higher risk of tumor-positive CRM and tend to exhibit deeper invasion in mid and low rectal cancer. Keywords: circumferential resection margin, depth of invasion, rectal cancer, tumor location

  13. French steam generator tubes: an overview of degradations

    International Nuclear Information System (INIS)

    Buisine, D.; Bouvier, O. de; Rupa, N.; Thebault, Y.; Barbe, V.; Pitner, P.

    2011-01-01

    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

  14. Clinical and endorectal ultrasound staging of circumferential rectal cancers

    International Nuclear Information System (INIS)

    Smith, A.; Farmer, K.C.; Chapple, K.

    2008-01-01

    Full text: Circumferential rectal cancers present at a more advanced stage than those located in a single quadrant. Although accurate staging is an important aspect of the preoperative management of the patient with a rectal cancer, the clinical and radiological staging of this subgroup of rectal cancer patients has been poorly studied. All patients with a rectal cancer were assessed clinically (by digital rectal examination and rigid sigmoidoscopy) before the radiological assessment by endorectal ultrasound (ERUS). Data collected included tumour height (distance from anal verge in centimetre) and tumour type (circumferential or non-circumferential). Radiological tumour staging was with the TNM system. Fifty-nine subjects (33 men, 26 women; median age 65 years (range 38-86 years)) were identified with a circumferential rectal cancer. Mean height of the cancer was 8 - 0.4 cm (standard error of the mean; range 2-13 cm). Forty-two cancers were palpable, and 17 cancers were impalpable. All cancers assessed clinically as circumferential were confirmed as circumferential on ERUS scanning. Tumour stage as assessed by ERUS was either T3 (n = 57) or T4 (n = 2). Nodal status was NO (n = 29) and N1 (n = 30). All rectal cancers assessed as circumferential on clinical examination have an ERUS stage of T3 or greater.

  15. 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 ...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...... in comparison with those treated by means of instrumented posterolateral lumbar fusion. SUMMARY OF BACKGROUND DATA: Circumferential fusion has become a common procedure in lumbar spinal fusion both as a primary and salvage procedure. However, the claimed advantages of circumferential fusion over conventional...

  16. Circumferential buckling instability of a growing cylindrical tube

    KAUST Repository

    Moulton, D.E.; Goriely, A.

    2011-01-01

    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

  17. 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.

    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

  18. 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.

  19. Experimental circumferential canaloplasty with a new Schlemm canal microcatheter

    Directory of Open Access Journals (Sweden)

    Mao-Song Xie

    2018-01-01

    Full Text Available AIM: To present a new, simple, inexpensive Schlemm canal microcatheter for circumferential canaloplasty in a rabbit model. METHODS: A rabbit glaucoma animal model was established by intravitreal injection of triamcinolone acetonide. Circumferential canaloplasty with a new Schlemm canal microcatheter (patent license number: 201220029850.0 was performed. The Schlemm canal microcatheter was composed of microcatheter wall and lumen. The wall was made of high refractive index plastic optical fiber that could be attached to an illuminant so that the whole lighted microcatheter was visible during circumferential canaloplasty. The lumen could be attached to an injector for injection of viscoelastic during catheterization. Rabbits were divided randomly into the control, model and treatment groups. Intraocular pressure (IOP was measured with a Tono-pen tonometer pre-operation and 3, 7, 14, 21 and 28d post-operation. Ultrasound biomicroscopy was performed to visualize the Schlemm canal microcatheter in the Schlemm canal and the sclera pool. RESULTS: The Schlemm canal microcatheter could be used to perform circumferential canaloplasty in the rabbit glaucoma animal model. IOP was lower in the treatment group than that in the model group 3, 7, 14 and 28d after operation. There were no significant differences in IOP between the control group and treatment group. The differences among the three groups were statistically significant (3d: F=41.985, P<0.001; 7d: F=65.696, P<0.001; 14d: F=114.599, P<0.001; 28d: F=55.006, P<0.001. CONCLUSION: Circumferential canaloplasty is safe and effective in control of experimental glaucoma model in rabbits.

  20. 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.

  1. J-integral estimation analysis for circumferential throughwall cracked pipes

    International Nuclear Information System (INIS)

    Zahoor, A.

    1988-01-01

    J-integral estimation solution is derived for pipes containing a circumferential throughwall crack. Bending moment and axial tension loadings are considered. These solutions are useful for calculating J from single load-displacement record obtained as part of pipe fracture testing, and are applicable for a wide range of flaw length to pipe circumference ratios. Results for J at initiation of crack growth generated using the solution developed in this paper agree well with J results from finite elements analyses. (orig.)

  2. J-integral estimation analysis for circumferential throughwall cracked pipes

    Energy Technology Data Exchange (ETDEWEB)

    Zahoor, A.

    J-integral estimation solution is derived for pipes containing a circumferential throughwall crack. Bending moment and axial tension loadings are considered. These solutions are useful for calculating J from single load-displacement record obtained as part of pipe fracture testing, and are applicable for a wide range of flaw length to pipe circumference ratios. Results for J at initiation of crack growth generated using the solution developed in this paper agree well with J results from finite elements analyses.

  3. Fracture toughness evaluation of circumferentially-cracked round bars

    International Nuclear Information System (INIS)

    Scibetta, M.

    1996-05-01

    The measure of the fracture toughness of a circumferentially-cracked round bar is generally performed through approximate formulae. Comparison of existing formulae to finite element results does not always show good agreement. Therefore an eta factor is introduced in order to improve the existing analytical formula. The axisymmetrical geometry is generally considered to be a high constrained geometry. Finite element calculations are performed to verify and quantify the constraint relative to the three point bending configuration (precracked Charpy)

  4. Circumferential wires as a supplement to intramedullary nailing in unstable trochanteric hip fractures

    DEFF Research Database (Denmark)

    Ban, Ilija; Birkelund, Lasse; Palm, Henrik

    2012-01-01

    Fixation of unstable trochanteric fractures is challenging. Application of a circumferential wire may facilitate bone contact and avoid postoperative fracture displacement. However, the use of circumferential wires remains controversial due to possible disturbance of the blood supply to the under......Fixation of unstable trochanteric fractures is challenging. Application of a circumferential wire may facilitate bone contact and avoid postoperative fracture displacement. However, the use of circumferential wires remains controversial due to possible disturbance of the blood supply...... to the underlying bone. We evaluated the results of applied circumferential wires, concentrating mainly on complications and reoperations....

  5. Improved circumferential shaft seal for aircraft gear transmissions

    Science.gov (United States)

    Ludwig, L. P.; Strom, T. N.

    1973-01-01

    Operation under simulated aircraft transmission conditions of speeds to 2850 m/min (9350 ft/min), lubricant temperatures to 394 K (250 F), shaft radial runouts to 0.254 mm (0.010 in.) F.I.R. (full indicator reading), and pressure differentials to 1.03 N/cm2 (1.5 psi) revealed that conventional circumferential seals leaked excessively. Modifying the conventional seal by adding helical grooves to the seal bore reduced leakage rates to within the acceptable level of 10 cm3/hr. The leakage rate of this modified seal was not significantly affected by lubricant flooding or by shaft radial runout.

  6. 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.

  7. Complete 360° circumferential SSOCT gonioscopy of the iridocorneal angle

    Science.gov (United States)

    McNabb, Ryan P.; Kuo, Anthony N.; Izatt, Joseph A.

    2014-02-01

    The ocular iridocorneal angle is generally an optically inaccessible area when viewed directly through the cornea due to the high angle of incidence required and the large index of refraction difference between air and cornea (nair = 1.000 and ncornea = 1.376) resulting in total internal reflection. Gonioscopy allows for viewing of the angle by removing the aircornea interface through the use of a special contact lens on the eye. Gonioscopy is used clinically to visualize the angle directly but only en face. Optical coherence tomography (OCT) has been used to image the angle and deeper structures via an external approach. Typically, this imaging technique is performed by utilizing a conventional anterior segment OCT scanning system. However, instead of imaging the apex of the cornea, either the scanner or the subject is tilted such that the corneoscleral limbus is orthogonal to the optical axis of the scanner requiring multiple volumes to obtain complete circumferential coverage of the ocular angle. We developed a novel gonioscopic OCT (GOCT) system that images the entire ocular angle within a single volume via an "internal" approach through the use of a custom radially symmetric gonioscopic contact lens. We present, to our knowledge, the first complete 360° circumferential volumes of the iridocorneal angle from a direct, internal approach.

  8. Ductile fracture of circumferentially cracked pipes subjected to bending loads

    International Nuclear Information System (INIS)

    Zahoor, A.; Kanninen, M.F.

    1981-01-01

    A plastic fracture mechanics methodology is presented for part-through cracks in pipes under bending. A previous analysis result on the behavior of part-through cracks in pipes is reviewed. Example quantitative results for the initiation and instability of radial growth of part-through cracks are presented and compared with the experimental data to demonstrate the applicability of the method. The analyses in our previous work are further developed to include the instability of circumferential growth of part-through cracks. Numerical results are then presented for a compliant piping system, under displacement controlled bending, which focus on (1) instability of radial growth (unstable wall breakthrough) and (2) instability of circumferential growth of the resulting throughthe-thickness crack. The combined results of the above two types of analyses are presented on a safety assessment diagram. This diagram defines a curve of critical combination of length and depth of part-through cracks which delineates leak from fracture. The effect of piping compliance on the leak-before-break assessment is discussed

  9. Ductile fracture of circumferentially cracked pipes subjected to bending loads

    Energy Technology Data Exchange (ETDEWEB)

    Zahoor, A.; Kanninen, M.F.

    1981-10-01

    A plastic fracture mechanics methodology is presented for part-through cracks in pipes under bending. A previous analysis result on the behavior of part-through cracks in pipes is reviewed. Example quantitative results for the initiation and instability of radial growth of part-through cracks are presented and compared with the experimental data to demonstrate the applicability of the method. The analyses in our previous work are further developed to include the instability of circumferential growth of part-through cracks. Numerical results are then presented for a compliant piping system, under displacement controlled bending, which focus on (1) instability of radial growth (unstable wall breakthrough) and (2) instability of circumferential growth of the resulting throughthe-thickness crack. The combined results of the above two types of analyses are presented on a safety assessment diagram. This diagram defines a curve of critical combination of length and depth of part-through cracks which delineates leak from fracture. The effect of piping compliance on the leak-before-break assessment is discussed.

  10. Early development of the circumferential axonal pathway in mouse and chick spinal cord.

    Science.gov (United States)

    Holley, J A

    1982-03-10

    The early development of the circumferential axonal pathway in the brachial and lumbar spinal cord of mouse and chick embryos was studied by scanning and transmission electron microscopy. The cellular processes which comprise this pathway grow in the transverse plane and along the lateral margin of the marginal zone (i.e., circumferentially oriented), as typified by the early embryonic commissural axons. The first formative event observed was in the ventrolateral margin of the primitive spinal cord ventricular zone. Cellular processes were found near the external limiting membrane that appeared to grow a variable distance either dorsally or ventrally. Later in development, presumptive motor column neurons migrated into the ventrolateral region, distal to these early circumferentially oriented processes. Concurrently, other circumferentially oriented perikarya and processes appeared along the dorsolateral margin. Due to their aligned sites of origin and parallel growth, the circumferential processes formed a more or less continuous line or pathway, which in about 10% of the scanned specimens could be followed along the entire lateral margin of the embryonic spinal cord. Several specimens later in development had two sets of aligned circumferential processes in the ventral region. Large numbers of circumferential axons were then found to follow the preformed pathway by fasciculation, after the primitive motor column had become established. Since the earliest circumferential processes appeared to differentiate into axons and were found nearly 24 hours prior to growth of most circumferential axons, their role in guidance as pioneering axons was suggested.

  11. Transient thermal stress problem for a circumferentially cracked hollow cylinder

    Science.gov (United States)

    Nied, H. F.; Erdogan, F.

    1982-01-01

    The transient thermal stress problem for a hollow elasticity cylinder containing an internal circumferential edge crack is considered. It is assumed that the problem is axisymmetric with regard to the crack geometry and the loading, and that the inertia effects are negligible. The problem is solved for a cylinder which is suddenly cooled from inside. First the transient temperature and stress distributions in an uncracked cylinder are calculated. By using the equal and opposite of this thermal stress as the crack surface traction in the isothermal cylinder the crack problem is then solved and the stress intensity factor is calculated. The numerical results are obtained as a function of the Fourier number tD/b(2) representing the time for various inner-to-outer radius ratios and relative crack depths, where D and b are respectively the coefficient of diffusivity and the outer radius of the cylinder.

  12. Measurements of the Exerted Pressure by Pelvic Circumferential Compression Devices

    Science.gov (United States)

    Knops, Simon P; van Riel, Marcel P.J.M; Goossens, Richard H.M; van Lieshout, Esther M.M; Patka, Peter; Schipper, Inger B

    2010-01-01

    Background: Data on the efficacy and safety of non-invasive Pelvic Circumferential Compression Devices (PCCDs) is limited. Tissue damage may occur if a continuous pressure on the skin exceeding 9.3 kPa is sustained for more than two or three hours. The aim of this study was to gain insight into the pressure build-up at the interface, by measuring the PCCD-induced pressure when applying pulling forces to three different PCCDs (Pelvic Binder® , SAM-Sling ® and T-POD® ) in a simplified model. Methods: The resulting exerted pressures were measured at four ‘anatomical’ locations (right, left, posterior and anterior) in a model using a pressure measurement system consisting of pressure cuffs. Results: The exerted pressure varied substantially between the locations as well as between the PCCDs. Maximum pressures ranged from 18.9-23.3 kPa and from 19.2-27.5 kPa at the right location and left location, respectively. Pressures at the posterior location stayed below 18 kPa. At the anterior location pressures varied markedly between the different PCCDs. Conclusion: The circumferential compression by the different PCCDs showed high pressures measured at the four locations using a simplified model. Difference in design and functional characteristics of the PCCDs resulted in different pressure build-up at the four locations. When following the manufacturer’s instructions, the exerted pressure of all three PCCDs tested exceeded the tissue damaging level (9.3 kPa). In case of prolonged use in a clinical situation this might put patients at risk for developing tissue damage. PMID:20361001

  13. Transpedicular fixation and fusion-arthrodesis circumferential for the treatment of lumbosacral spondylolisthesis of high degree - Multi centric experience

    International Nuclear Information System (INIS)

    Javier Matta Ibarra; Mauricio Rozo Franco; Francisco Restrepo Suarez

    2004-01-01

    The objective is to present the high-grade lumbosacral spondylolisthesis surgical experience. Spondylolisthesis causes chronic disabling pain, postural alteration and/or motor and sensory deficits in the lower extremities. Surgical stabilization is recommended in symptomatic adult and even in children or adolescents without symptoms because of the deformity progression potential. Stabilization can be done with or without reduction of the slippage; reduction implies neurological damage risk, bone (loosening) or implant (rupture) failure. Many authors recommended to do an in situ circumferential fusion arthrosis (inter body and inter transverse) associated with a transpedicular fixation in order to minimize the described risk. Eight patients were operated from 1993 to 2002. spondylolisthesis was analyzed according to clinical presentation, neurological dysfunction, postural alterations (slip angle, sacral inclination) complications and follow up. During follow up solid fusion was obtained with a better neurological function in all cases. One patient presented with a drop foot that reverted posteriorly; other patient had a superficial infection of the wound that was controlled. Slip angle improved between 8 - 42 and sacral inclination to 20 degrades. Present technique is recommended because it can be done a circumferential in situ arthrodesis in a single stage operation

  14. Rectal cancer: involved circumferential resection margin - a root cause analysis.

    Science.gov (United States)

    Youssef, H; Collantes, E C; Rashid, S H; Wong, L S; Baragwanath, P

    2009-06-01

    An involved circumferential resection margin (CRM) following surgery for rectal cancer is the strongest predictor of local recurrence and may represent a failure of the multidisciplinary team (MDT) process. The study analyses the causes of positive CRM in patients undergoing elective surgery for rectal cancer with respect to the decision-making process of the MDT, preoperative rectal cancer staging and surgical technique. From March 2002 to September 2005, data were collected prospectively on all patients undergoing elective rectal cancer surgery with curative intent. The data on all patients identified with positive CRM were analysed. Of 158 patients (male:female = 2.2:1) who underwent potentially curative surgery, 16 (10%) patients had a positive CRM on postoperative histology. Four were due to failure of the pelvic magnetic resonance imaging (MRI) staging scans to predict an involved margin, two with an equivocal CRM on MRI did not have preoperative radiotherapy, one had an inaccurate assessment of the site of primary tumour and in one intra-operative difficulty was encountered. No failure of staging or surgery was identified in the remaining eight of the 16 patients. Abdominoperineal resection (APR) was associated with a 26% positive CRM, compared with 5% for anterior resection. No single consistent cause was found for a positive CRM. The current MDT process and/or surgical technique may be inadequate for low rectal tumours requiring APR.

  15. Fracture behavior of short circumferentially surface-cracked pipe

    International Nuclear Information System (INIS)

    Krishnaswamy, P.; Scott, P.; Mohan, R.

    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

  16. 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.

  17. Nickel-titanium wire in circumferential suture of a flexor tendon repair: a comparison to polypropylene.

    Science.gov (United States)

    Karjalainen, T; He, M; Chong, A K S; Lim, A Y T; Ryhanen, J

    2010-07-01

    Nickel-titanium (NiTi) has been proposed as an alternative material for flexor tendon core suture. To our knowledge, its suitability as a circumferential suture of flexor tendon repair has not been investigated before. The purpose of this ex vivo study was to investigate the biomechanical properties of NiTi circumferential repairs and to compare them with commonly used polypropylene. Forty porcine flexor tendons were cut and repaired by simple running or interlocking mattress technique using 100 microm NiTi wire or 6-0 polypropylene. The NiTi circumferential repairs showed superior stiffness, gap resistance, and load to failure when compared to polypropylene repairs with both techniques. Nickel-titanium wire seems to be a potential material for circumferential repair of flexor tendons. Copyright 2010 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

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

    NARCIS (Netherlands)

    Gietelink, Lieke; Wouters, Michel W. J. M.; Tanis, Pieter J.; Deken, Marion M.; ten Berge, Martijn G.; Tollenaar, Rob A. E. M.; van Krieken, J. Han; de Noo, Mirre E.

    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

  19. 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.

  20. 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

  1. Experimental Observation of Cumulative Second-Harmonic Generation of Circumferential Guided Wave Propagation in a Circular Tube

    International Nuclear Information System (INIS)

    Deng Ming-Xi; Gao Guang-Jian; Li Ming-Liang

    2015-01-01

    The experimental observation of cumulative second-harmonic generation of the primary circumferential guided wave propagation is reported. A pair of wedge transducers is used to generate the primary circumferential guided wave desired and to detect its fundamental-frequency and second-harmonic amplitudes on the outside surface of the circular tube. The amplitudes of the fundamental waves and the second harmonics of the circumferential guided wave propagation are measured for different separations between the two wedge transducers. At the driving frequency where the primary and the double-frequency circumferential guided waves have the same linear phase velocities, the clear second-harmonic signals can be observed. The quantitative relationships between the second-harmonic amplitudes and circumferential angle are analyzed. It is experimentally verified that the second harmonics of primary circumferential guided waves do have a cumulative growth effect with the circumferential angle. (paper)

  2. Risk Factors Associated With Circumferential Resection Margin Positivity in Rectal Cancer: A Binational Registry Study.

    Science.gov (United States)

    Warrier, Satish K; Kong, Joseph Cherng; Guerra, Glen R; Chittleborough, Timothy J; Naik, Arun; Ramsay, Robert G; Lynch, A Craig; Heriot, Alexander G

    2018-04-01

    Rectal cancer outcomes have improved with the adoption of a multidisciplinary model of care. However, there is a spectrum of quality when viewed from a national perspective, as highlighted by the Consortium for Optimizing the Treatment of Rectal Cancer data on rectal cancer care in the United States. The aim of this study was to assess and identify predictors of circumferential resection margin involvement for rectal cancer across Australasia. A retrospective study from a prospectively maintained binational colorectal cancer database was interrogated. This study is based on a binational colorectal cancer audit database. Clinical information on all consecutive resected rectal cancer cases recorded in the registry from 2007 to 2016 was retrieved, collated, and analyzed. The primary outcome measure was positive circumferential resection margin, measured as a resection margin ≤1 mm. A total of 3367 patients were included, with 261 (7.5%) having a positive circumferential resection margin. After adjusting for hospital and surgeon volume, hierarchical logistic regression analysis identified a 6-variable model encompassing the independent predictors, including urgent operation, abdominoperineal resection, open technique, low rectal cancer, T3 to T4, and N1 to N2. The accuracy of the model was 92.3%, with an receiver operating characteristic of 0.783 (p risk associated with circumferential resection margin positivity ranged from risk factors) to 43% (6 risk factors). This study was limited by the lack of recorded long-term outcomes associated with circumferential resection margin positivity. The rate of circumferential resection margin involvement in patients undergoing rectal cancer resection in Australasia is low and is influenced by a number of factors. Risk stratification of outcome is important with the increasing demand for publicly accessible quality data. See Video Abstract at http://links.lww.com/DCR/A512.

  3. Modification of the ASME code z-factor for circumferential surface crack in nuclear ferritic pipings

    International Nuclear Information System (INIS)

    Choi, Young Hwan; Chung, Yon Ki; Koh, Wan Young; Lee, Joung Bae

    1996-01-01

    The purpose of this paper is to modify the ASME Code Z-Factor, which is used in the evaluation of circumferential surface crack in nuclear ferritic pipings. The ASME Code Z-Factor is a load multiplier to compensate plastic load with elasto-plastic load. The current ASME Code Z-Factor underestimates pipe maximum load. In this study, the original SC. TNP method is modified first because the original SC. TNP method has a problem that the maximum allowable load predicted from the original SC. TNP method is slightly higher than that measured from the experiment. Then the new Z-Factor is developed using the modified SC. TNP method. The desirability of both the modified SC. TNP method and the new Z-Factor is examined using the experimental results for the circumferential surface crack in pipings. The results show that (1) the modified SC. TNP method is good for predicting the circumferential surface crack behavior in pipings, and (2) the Z-Factor obtained from the modified SC. TNP method well predicts the behavior of circumferential surface crack in ferritic pipings. 30 refs., 13 figs., 4 tabs. (author)

  4. MEMS-based non-rotatory circumferential scanning optical probe for endoscopic optical coherence tomography

    Science.gov (United States)

    Xu, Yingshun; Singh, Janak; Siang, Teo Hui; Ramakrishna, Kotlanka; Premchandran, C. S.; Sheng, Chen Wei; Kuan, Chuah Tong; Chen, Nanguang; Olivo, Malini C.; Sheppard, Colin J. R.

    2007-07-01

    In this paper, we present a non-rotatory circumferential scanning optical probe integrated with a MEMS scanner for in vivo endoscopic optical coherence tomography (OCT). OCT is an emerging optical imaging technique that allows high resolution cross-sectional imaging of tissue microstructure. To extend its usage to endoscopic applications, a miniaturized optical probe based on Microelectromechanical Systems (MEMS) fabrication techniques is currently desired. A 3D electrothermally actuated micromirror realized using micromachining single crystal silicon (SCS) process highlights its very large angular deflection, about 45 degree, with low driving voltage for safety consideration. The micromirror is integrated with a GRIN lens into a waterproof package which is compatible with requirements for minimally invasive endoscopic procedures. To implement circumferential scanning substantially for diagnosis on certain pathological conditions, such as Barret's esophagus, the micromirror is mounted on 90 degree to optical axis of GRIN lens. 4 Bimorph actuators that are connected to the mirror on one end via supporting beams and springs are selected in this micromirror design. When actuators of the micromirror are driven by 4 channels of sinusoidal waveforms with 90 degree phase differences, beam focused by a GRIN is redirected out of the endoscope by 45 degree tilting mirror plate and achieve circumferential scanning pattern. This novel driving method making full use of very large angular deflection capability of our micromirror is totally different from previously developed or developing micromotor-like rotatory MEMS device for circumferential scanning.

  5. Consideration on evaluation of internal pressure creep rupture for tube with circumferential joint

    International Nuclear Information System (INIS)

    Nagato, Kotaro; Satoh, Keisuke

    1983-01-01

    The behavior of internal pressure creep rupture of the thin-walled cylinders with circumferential joints is affected by the combination of creep characteristics of parent materials and weld metals. In particular, the compatibility of the creep strain rate of parent materials and weld metals becomes an important controlling factor. The behavior of internal pressure creep of the welded parts in circumferential joint cylinders can be evaluated simply with the uniaxial creep data of parent materials and weld metals, considering it by approximately substituting with the creep behavior of a uniaxial longitudinal joint. The method of evaluation is, first, to analyze the breaking behavior of uniaxial longitudinal joints using the uniaxial creep characteristic values of parent materials and weld metals, and next, by combining the equation for the relation between the rupture times of uniaxial creep and internal pressure creep with the analyzed breaking behavior of uniaxial joints, the internal pressure creep rupture behavior of the cylinders with circumferential joints can be evaluated. The internal pressure creep behavior of the thin-walled cylinders with circumferential joints, their rupture life and the uniaxial creep rupture life of longitudinal joints, and the examination of Hastelloy X cylinders are reported. (Kako, I.)

  6. The prediction of the-circumferential fuel-temperature distribution under ballonian condition. Vol. 3

    Energy Technology Data Exchange (ETDEWEB)

    Abdallah, A M; El-Sherbiny, E M [Reactor Department, Nuclear Research Center, Atomic Energy Authority, Cairo (Egypt)

    1996-03-01

    Swelling and thermal distortion of nuclear fuel elements due to depressurization of reactor coolant may cause contracts in points or finite regions between adjacent fuel elements in square and triangle lattices. This is very probable in Advanced Pressurized Water Reactors where the clearance between fuel elements is about 1 mm. This results in partial blocking of the coolant flow and formation of hot spots in the contact regions. In these regions, absence of coolant results in nonuniform clad circumferential temperature distribution. This causes excessive thermal stresses which may produce local melting or clad failure. An accurate prediction of the clad circumferential temperature distribution during these severe incidents is very important. This problem was studied numerically during transient and steady state conditions. Recently, a semi analytical solution for the underlying problem was derived assuming the heat transfer coefficient to vary linearly with the circumferential distance measured from the cusp point, and the heat flux at the fuel-clad interface to be a constant quantity. In the present work, an approximate analytic solution is obtained. The accuracy is tested by solving the problem numerically. Also the problem is reanalyzed by considering the heat flux at the fuel-clad interface to be a power function of the angular distance along the clad surface. Moreover, the heat transfer coefficient is assumed to be a function of both the circumferential coordinate and temperature of the clad. Discussion of the analytical solution and the assumptions are rationalized in the text. 4 figs.

  7. 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.

  8. Circumferential Stent Fracture: Novel Detection and Treatment with the Use of StentBoost

    OpenAIRE

    Ramegowda, Raghu T.; Chikkaswamy, Srinivas B.; Bharatha, Ashalatha; Radhakrishna, Jayashree; Krishnanaik, Geetha B.; Nanjappa, Manjunath C.; Panneerselvam, Arunkumar

    2012-01-01

    Circumferential stent fracture is extremely uncommon, and in rare cases, it can cause stent thrombosis. Recognizing stent fracture can be difficult on conventional fluoroscopy because of poor stent radiopacity. We found that StentBoost image acquisition yields improved visibility of stent struts, enabling the identification of stent fracture and the precise positioning of new stents over previously stented segments.

  9. Prognostic Value of the Circumferential Resection Margin in Esophageal Cancer Patients After Neoadjuvant Chemoradiotherapy

    NARCIS (Netherlands)

    Hulshoff, J. B.; Faiz, Z.; Karrenbeld, A.; Kats-Ugurlu, G.; Burgerhof, J. G. M.; Smit, J. K.; Plukker, J. Th. M.

    2015-01-01

    Background. Circumferential resection margins (CRM) for esophageal cancer (EC), defined by the College of American Pathologists (CAP; >0 mm) or the Royal College of Pathologists (RCP; >1 mm) as tumor-free (R0), are based on a surgery-alone approach. We evaluated the usefulness of both definitions in

  10. Crack-opening area calculations for circumferential through-wall pipe cracks

    Energy Technology Data Exchange (ETDEWEB)

    Kishida, K.; Zahoor, A.

    1988-08-01

    This report describes the estimation schemes for crack opening displacement (COD) of a circumferential through-wall crack, then compares the COD predictions with pipe experimental data. Accurate predictions for COD are required to reliably predict the leak rate through a crack in leak-before-break applications.

  11. Crack-opening area calculations for circumferential through-wall pipe cracks

    International Nuclear Information System (INIS)

    Kishida, K.; Zahoor, A.

    1988-08-01

    This report describes the estimation schemes for crack opening displacement (COD) of a circumferential through-wall crack, then compares the COD predictions with pipe experimental data. Accurate predictions for COD are required to reliably predict the leak rate through a crack in leak-before-break applications

  12. 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%.

  13. Crack resistance of austenitic pipes with circumferential through-wall cracks

    International Nuclear Information System (INIS)

    Foerster, K.; Grueter, L.; Setz, W.; Bhandari, S.; Debaene, J.P.; Faidy, C.; Schwalbe, K.H.

    1993-01-01

    For monotonously increasing load the correct evaluation of the crack resistance properties of a structure is essential for safety analyses. Considerable attention has been given to the through-wall case, since this is generally believed to be the controlling case with regard to complete pipe failure. The maximum load conditions for circumferential crack growth in pipes under displacement-controlled loadings has been determined. The need for crack resistance curves, measured on circumferentially through-wall cracked straight pipes of austenitic stainless steel 316L under bending, is emphasized by the limitation in the data range on small specimens and by the differences in the procedures. To answer open questions and to improve calculational methods a joint fracture mechanics program is being performed by Electricite de France, Novatome and Siemens-Interatom. The working program contains experimental and theoretical investigations on the applicability of small-specimen data to real structures. 10 refs., 10 figs., 4 tabs

  14. Low cycle fatigue of pressurized pipes with circumferential flaws under cyclic bending moment

    International Nuclear Information System (INIS)

    Stoppler, W.; Sturm, D.

    1993-01-01

    Pipes of 706 mm inner diameter, 47 mm wall thickness and about 5,000 mm in length were provided with circumferential surface cracks and loaded by internal pressure of 15 MPa whilst being simultaneously subjected to an alternating external bending moment. Usually a load ratio R of -1 (M min /M max ), in one case R = 0.1, was applied. The pipes were fabricated of two types of ferritic steel: one, grade 20 MnMoNi 5 5, with a high upper shelf impact energy of about 200 J and one, MnMoNiV-special melt, with a low upper shelf impact energy of about 60 J. Deformation and crack growth in the wall thickness and circumferential direction were determined and compared with calculated values. 9 refs., 13 figs

  15. 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.

  16. 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

    employment was also monitored. Bootstrapped mean differences in discounted costs and benefits were generated in order to explore cost-effectiveness. RESULTS: A significant cost difference of pound 1950 (95% CI, pound 849 to pound 3145) in favor of FRA was found. Mean QALYs per patient over the 24-month trial......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 spinal...... is less effective and, all things being equal, is assumed more costly than FRA. METHODS: Eighty-three patients were randomly allocated to receive either the TC or FRA as part of a circumferential lumbar fusion between 1998 and 2002. NHS costs related to the surgery and revision surgery needed during...

  17. Standard practice for estimating the approximate residual circumferential stress in straight thin-walled tubing

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2007-01-01

    1.1 A qualitative estimate of the residual circumferential stress in thin-walled tubing may be calculated from the change in outside diameter that occurs upon splitting a length of the tubing. This practice assumes a linear stress distribution through the tube wall thickness and will not provide an estimate of local stress distributions such as surface stresses. (Very high local residual stress gradients are common at the surface of metal tubing due to cold drawing, peening, grinding, etc.) The Hatfield and Thirkell formula, as later modified by Sachs and Espey, provides a simple method for calculating the approximate circumferential stress from the change in diameter of straight, thin-walled, metal tubing. 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  18. Plastic fracture instability analysis of wall breakthrough in a circumferentially cracked pipe subjected to bending loads

    International Nuclear Information System (INIS)

    Zahoor, A.; Kanninen, M.F.

    1981-01-01

    A method of analyzing internal surface circumferential cracks in ductile reactor piping is presented. The method utilizes an alternate but equivalent definition of the J-integral based on nonlinear structural compliance. The analysis is valid for situations where the cross section containing the crack is fully yielded. Results are obtained for radial and circumferential crack growth for pipes subjected to bending. The stability of radial crack growth (wall breakthrough) is assessed using the J-integral-based tearing modulus approach. The analysis is shown to be in agreement with experimental results on the stability of surface crack growth in Type 304 stainless stee pipes. Example quantitative results for fracture instability assessments for nuclear piping are presented. 23 refs

  19. Plastic fracture instability analysis of wall breakthrough in a circumferentially cracked pipe subjected to bending loads

    Energy Technology Data Exchange (ETDEWEB)

    Zahoor, A.; Kanninen, M.F.

    1981-07-01

    A method of analyzing internal surface circumferential cracks in ductile reactor piping is presented. The method utilizes an alternate but equivalent definition of the J-integral based on nonlinear structural compliance. The analysis is valid for situations where the cross section containing the crack is fully yielded. Results are obtained for radial and circumferential crack growth for pipes subjected to bending. The stability of radial crack growth (wall breakthrough) is assessed using the J-integral-based tearing modulus approach. The analysis is shown to be in agreement with experimental results on the stability of surface crack growth in Type 304 stainless stee pipes. Example quantitative results for fracture instability assessments for nuclear piping are presented. 23 refs.

  20. Circumferential Ciliary Body Cysts Presenting as Acute Pigment Dispersion and Ocular Hypertension.

    Science.gov (United States)

    Sarıgül Sezenöz, Almila; Güngör, Sirel Gür; Kıratlı, Hayyam; Akman, Ahmet

    2017-09-15

    To report a case of circumferential neuroepithelial cyst of the ciliary body presenting with pigment dispersion (PD) and ocular hypertension. 48-year-old female patient presented with a complaint of pain in the left eye. On examination, visual acuity of the left eye was 0.9, and the intraocular pressure was 48 mmHg. Biomicroscopic anterior segment examination of the left eye revealed 4+ pigmented cells in the anterior chamber. Active PD from the pupillary region at 11 o'clock was noticed at the time of the examination. Ultrasound biomicroscopy demonstrated 360º cystic lesions of the ciliary body in the left eye. The patient was diagnosed as neuroepithelial cyst of the ciliary body. Our case is unique as it is the first case of circumferential neuroepithelial ciliary body cyst presenting with acute PD and ocular hypertension.

  1. Nonlinear Analysis of Two-phase Circumferential Motion in the Ablation Circumstance

    Science.gov (United States)

    Xiao-liang, Xu; Hai-ming, Huang; Zi-mao, Zhang

    2010-05-01

    In aerospace craft reentry and solid rocket propellant nozzle, thermal chemistry ablation is a complex process coupling with convection, heat transfer, mass transfer and chemical reaction. Based on discrete vortex method (DVM), thermal chemical ablation model and particle kinetic model, a computational module dealing with the two-phase circumferential motion in ablation circumstance is designed, the ablation velocity and circumferential field can be thus calculated. The calculated nonlinear time series are analyzed in chaotic identification method: relative chaotic characters such as correlation dimension and the maximum Lyapunov exponent are calculated, fractal dimension of vortex bulbs and particles distributions are also obtained, thus the nonlinear ablation process can be judged as a spatiotemporal chaotic process.

  2. 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.

  3. Failure Assessment for the High-Strength Pipelines with Constant-Depth Circumferential Surface Cracks

    OpenAIRE

    X. Liu; Z. X. Lu; Y. Chen; Y. L. Sui; L. H. Dai

    2018-01-01

    In the oil and gas transportation system over long distance, application of high-strength pipeline steels can efficiently reduce construction and operation cost by increasing operational pressure and reducing the pipe wall thickness. Failure assessment is an important issue in the design, construction, and maintenance of the pipelines. The small circumferential surface cracks with constant depth in the welded pipelines are of practical interest. This work provides an engineering estimation pr...

  4. Positioning means for circumferentially locating inspection apparatus in a nuclear reactor vessel

    International Nuclear Information System (INIS)

    Burns, D.C.

    1979-01-01

    Positioning means for locating inspection apparatus used to volumetrically examine a nuclear reactor vessel is disclosed. The positioning means is provided with a support ring having an annular key positioned longitudinally about its periphery. Three support legs are attached to the support ring by brackets adapted to fit the annular key. The support ring also carries three guide stud bushings which are movably mounted by clamps adapted to engage the support ring key. Prior to lowering the inspection apparatus into the vessel, the guide stud bushings are each moved to a point of alignment with one of three guide studs extending upwardly from the vessel. After alignment has been verified, the guide stud bushings are clamped in position. The inspection apparatus is lowered towards its fully seated position within the vessel and is coarsely circumferentially positioned with by the engagement of the guide studs within the guide stud bushings. A fine degree of circumferential positioning is achieved by providing a specially configured shoe for one of the support legs. With the core barrel internals in, the special shoe is adapted to key onto a core barrel pin the exact location of which is known. With the core barrel internals removed, the special shoe is adapted to place a locating key into a notch in a vessel flange, the location of which is known. As the inspection apparatus is lowered into its fully seated position, exact circumferential positioning with respect to the vessel is achieved. The other support legs rest on an inner circumferential flange so that no portion of the inspection apparatus touches or threatens the vessel's top flange. 19 claims

  5. Burnout in a channel with non-uniform circumferential heat flux

    International Nuclear Information System (INIS)

    Lee, D.H.

    1966-03-01

    Burnout experiments are reported for uniform flux and circumferential flux tilt (maximum/average flux about 1.25) with tubes and annuli, all the experiments having uniform axial heating. These show similar results, the burnout power with flux tilt being within 10% of that with uniform flux. For the same mean exit steam quality, the local maximum flux is higher than the predicted burnout value and generally a better prediction is obtained using the average flux. (author)

  6. ELESTRES: performance of nuclear fuel, circumferential ridging, and multiaxial elastic-plastic stresses in sheaths

    International Nuclear Information System (INIS)

    Tayal, M.

    1986-10-01

    The finite element code ELESTRES models the two-dimensional axisymmetric behaviour of a CANDU fuel element during normal operation. The main focus of the code is to estimate temperatures, fission gas release, and axial variations of deformation/stresses in the pellet and in the sheath. Thus the code is able to predict details like stresses/strains at circumferential ridges. This paper describes the current version of ELESTRES. The emphasis is on a recent addition: multiaxial stresses in the sheath near circumferential ridges. For accuracy in the critical region, a fine mesh is used near the ridge. To keep computing costs low, a coarse mesh is used near the midplane of the pellet. Predictions of ELESTRES show good agreement with abouth 80 measurements of fission-gas-release. In this paper, we also present ELESTRES predictions of hoop strains in sheaths, for two irradiations: element ABS and bundle GB. For both irradiations, predictions, compare favourably with measurements. An illustrative example shows that near circumferential ridges, bending contributes to multiaxial stresses in the sheath. This can have a significant effect on sheath integrity, such as during stress-corrosion-cracking due to power-increases, or during corrosion-assisted-fatigue due to power cycling

  7. Esophageal circumferential en bloc endoscopic submucosal dissection: assessment of a new technique.

    Science.gov (United States)

    Barret, Maximilien; Pratico, Carlos Alberto; Beuvon, Frédéric; Mangialavori, Luigi; Chryssostalis, Ariane; Camus, Marine; Chaussade, Stanislas; Prat, Frédéric

    2013-10-01

    Endoscopic esophageal piecemeal mucosectomy for high-grade dysplasia on Barrett's esophagus leads to suboptimal histologic evaluation, as well as recurrence on remaining mucosa. Circumferential en bloc mucosal resection would significantly improve the management of dysplastic Barrett's esophagus. Our aim was to describe a new method of esophageal circumferential endoscopic en bloc submucosal dissection (CESD) in a swine model. After submucosal injection, circumferential incision was performed at each end of the esophageal segment to be removed. Mechanical submucosal dissection was performed from the proximal to the distal incision, using a mucosectomy cap over the endoscope. The removed mucosal ring was retrieved. Clinical, endoscopic, and histologic data were prospectively collected. Esophageal CESD was conducted on 5 pigs. A median mucosal length of 6.5 cm (range, 4 to 8 cm) was removed in the lower third of the esophagus. The mean duration of the procedure was 36 minutes (range, 17 to 80 min). No procedure-related complication, including perforation, was observed. All animals exhibited a mild esophageal stricture at day 7, and a severe symptomatic stricture at day 14. Necropsy confirmed endoscopic findings with cicatricial fibrotic strictures. On histologic examination, an inflammatory cell infiltrate, diffuse fibrosis reaching the muscular layer, and incomplete reepithelialization were observed. CESD enables expeditious resection and thorough examination of large segments of esophageal mucosa in safe procedural conditions, but esophageal strictures occur in the majority of the cases. Efficient methods for stricture prevention are needed for this technique to be developed in humans.

  8. Single stage circumferential lingual mucosal graft urethroplasty in near obliterative bulbar urethra stricture: A novel technique.

    Science.gov (United States)

    Sharma, Umesh; Yadav, Sher Singh; Tomar, Vinay; Garg, Amit

    2016-01-01

    This is a prospective study of the use and efficacy of a novel technique of circumferential tubularised lingual mucosal graft (LMG) in obliterative and near obliterative bulbar urethral stricture of >2 cm where excisional and augmented anastomotic urethroplasty are not feasible. The stenotic urethral segment was opened dorsally in midline and fibrosed urethra was excised taking care to preserve the healthy spongiosum tissue. LMG (av. Length 3 cm) was placed from one end of corporal body towards spongy tissue in a circumferential manner. Another LMG was placed in similar manner to deal with longer stricture. The urethra was tubularised over 14 Fr silicone catheter. A total of 12 men, of mean age 47 years underwent this procedure. The mean follow up period was 11 months starting from July 2014 till manuscript submission. Follow up included voiding cystourethrogram at 3 weeks, cystoscopy at 3 months (one patient didn't turned up) and subsequent follow up. Mean stricture length was 4.66 cm (range, 3-8.5 cm) and mean operative time was 195 min. (range, 160 to 200 min.). The technique was successful (normal voiding with no need for any post-operative procedure) in 11(91.6%) patients. One patient developed early recurrence at 4 month of surgery and had anastomotic stricture which was successfully managed by direct visual internal urethrotomy. Single stage circumferential tubularised graft urethroplasty is an excellent technique for strictures that include segments of obliterative and near obliterative diseased urethra. It provide a wider neourethra than patch graft urethroplasty.

  9. Failure Assessment for the High-Strength Pipelines with Constant-Depth Circumferential Surface Cracks

    Directory of Open Access Journals (Sweden)

    X. Liu

    2018-01-01

    Full Text Available In the oil and gas transportation system over long distance, application of high-strength pipeline steels can efficiently reduce construction and operation cost by increasing operational pressure and reducing the pipe wall thickness. Failure assessment is an important issue in the design, construction, and maintenance of the pipelines. The small circumferential surface cracks with constant depth in the welded pipelines are of practical interest. This work provides an engineering estimation procedure based upon the GE/EPRI method to determine the J-integral for the thin-walled pipelines with small constant-depth circumferential surface cracks subject to tension and bending loads. The values of elastic influence functions for stress intensity factor and plastic influence functions for fully plastic J-integral estimation are derived in tabulated forms through a series of three-dimensional finite element calculations for different crack geometries and material properties. To check confidence of the J-estimation solution in practical application, J-integral values obtained from detailed finite element (FE analyses are compared with those estimated from the new influence functions. Excellent agreement of FE results with the proposed J-estimation solutions for both tension and bending loads indicates that the new solutions can be applied for accurate structural integrity assessment of high-strength pipelines with constant-depth circumferential surface cracks.

  10. 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.

  11. Circumferential and fusiform intracranial aneurysms: reconstructive endovascular treatment with self-expandable stents

    Energy Technology Data Exchange (ETDEWEB)

    Lubicz, Boris [Erasme University Hospital, Department of Neuroradiology, Brussels (Belgium); Hopital Erasme, Service de Radiologie (EA 2691), Brussels (Belgium); Collignon, Laurent; Baleriaux, Danielle [Erasme University Hospital, Department of Neuroradiology, Brussels (Belgium); Lefranc, Florence; Bruneau, Michael; Brotchi, Jacques; Witte, Olivier de [Erasme University Hospital, Department of Neurosurgery, Brussels (Belgium)

    2008-06-15

    We report our experience with endovascular treatment (EVT) of circumferential and fusiform intracranial aneurysms by a reconstructive approach with self-expandable stents. A retrospective review of our prospectively maintained database identified all circumferential and fusiform aneurysms treated by a reconstructive endovascular approach over a 3-year period. Clinical charts, procedural data, and angiographic results were reviewed. From April 2004 to May 2007, 13 patients were identified, of whom 12 were asymptomatic and 1 presented with a subarachnoid hemorrhage. Two patients with an aneurysm {<=}2 mm were treated by stent-within-stent placement without coiling (group 1). In 11 patients with a larger aneurysm, stenting with subsequent coiling was performed (group 2). In this latter approach, a balloon was temporarily inflated within the stent to ensure safe coil delivery. All patients showed an excellent clinical outcome. Asymptomatic procedural complications occurred in three patients, two with cervical internal carotid artery dissection and one with retroperitoneal hematoma. In patients of group 1, the aneurysm had completely disappeared at 6 months. In patients of group 2, aneurysm occlusion was complete in three and incomplete in eight. Follow-up angiography in 12 patients showed four with further thrombosis, six with stable results, and two with minor recanalization. Circumferential and fusiform intracranial aneurysms may be treated by a reconstructive endovascular approach with self-expandable stents. In small aneurysms, a stent-within-stent technique is effective, whereas stenting and subsequent coiling is indicated in larger aneurysms. This therapeutic protocol is associated with good clinical and anatomical results. (orig.)

  12. 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.

  13. 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

  14. Comparison of instrumented anterior interbody fusion with instrumented circumferential lumbar fusion.

    Science.gov (United States)

    Madan, S S; Boeree, N R

    2003-12-01

    Posterior lumbar interbody fusion (PLIF) restores disc height, the load bearing ability of anterior ligaments and muscles, root canal dimensions, and spinal balance. It immobilizes the painful degenerate spinal segment and decompresses the nerve roots. Anterior lumbar interbody fusion (ALIF) does the same, but could have complications of graft extrusion, compression and instability contributing to pseudarthrosis in the absence of instrumentation. The purpose of this study was to assess and compare the outcome of instrumented circumferential fusion through a posterior approach [PLIF and posterolateral fusion (PLF)] with instrumented ALIF using the Hartshill horseshoe cage, for comparable degrees of internal disc disruption and clinical disability. It was designed as a prospective study, comparing the outcome of two methods of instrumented interbody fusion for internal disc disruption. Between April 1994 and June 1998, the senior author (N.R.B.) performed 39 instrumented ALIF procedures and 35 instrumented circumferential fusion with PLIF procedures. The second author, an independent assessor (S.M.), performed the entire review. Preoperative radiographic assessment included plain radiographs, magnetic resonance imaging (MRI) and provocative discography in all the patients. The outcome in the two groups was compared in terms of radiological improvement and clinical improvement, measured on the basis of improvement of back pain and work capacity. Preoperatively, patients were asked to fill out a questionnaire giving their demographic details, maximum walking distance and current employment status in order to establish the comparability of the two groups. Patient assessment was with the Oswestry Disability Index, quality of life questionnaire (subjective), pain drawing, visual analogue scale, disability benefit, compensation status, and psychological profile. The results of the study showed a satisfactory outcome (scorelife questionnaire) score of 71.8% (28 patients) in

  15. Clinical implication of negative conversion of predicted circumferential resection margin status after preoperative chemoradiotherapy for locally advanced rectal cancer

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Nam Kwon [Department of Radiation Oncology, Korea University Medical Center, Korea University College of Medicine, Seoul (Korea, Republic of); Kim, Chul Yong, E-mail: kcyro@korea.ac.kr [Department of Radiation Oncology, Korea University Medical Center, Korea University College of Medicine, Seoul (Korea, Republic of); Park, Young Je; Yang, Dae Sik; Yoon, Won Sup [Department of Radiation Oncology, Korea University Medical Center, Korea University College of Medicine, Seoul (Korea, Republic of); Kim, Seon Hahn; Kim, Jin [Division of Colorectal Surgery, Department of Surgery, Korea University Medical Center, Korea University College of Medicine, Seoul (Korea, Republic of)

    2014-02-15

    Objective: To evaluate the prognostic implication of the negative conversion of predicted circumferential resection margin status before surgery in patients with locally advanced rectal cancer with predicted circumferential resection margin involvement. Methods: Thirty-eight patients (28 men, 10 women; median age, 61 years; age range, 39–80 years) with locally advanced rectal cancer with predicted circumferential resection margin involvement who underwent preoperative chemoradiotherapy followed by radical surgery were analyzed. Involvement of the circumferential resection margin was predicted on the basis of pre- and post-chemoradiotherapy magnetic resonance imaging. The primary endpoints were 3-year local recurrence-free survival and overall survival. Results: The median follow-up time was 41.1 months (range, 13.9–85.2 months). The negative conversion rate of predicted circumferential resection margin status after preoperative chemoradiotherapy was 65.8%. Patients who experienced negative conversion of predicted circumferential resection margin status had a significantly higher 3-year local recurrence-free survival rate (100.0% vs. 76.9%; P = 0.013), disease-free survival rate (91.7% vs. 59.3%; P = 0.023), and overall survival rate (96.0% vs. 73.8%; P = 0.016) than those who had persistent circumferential resection margin involvement. Conclusions: The negative conversion of the predicted circumferential resection margin status as predicted by magnetic resonance imaging will assist in individual risk stratification as a predictive factor for treatment response and survival before surgery. These findings may help physicians determine whether to administer more intense adjuvant chemotherapy or change the surgical plan for patients displaying resistance to preoperative chemoradiotherapy.

  16. An efficient and low resistant circumferential overlap trisection helical baffle heat exchanger with folded baffles

    International Nuclear Information System (INIS)

    Dong, Cong; Li, Dongshuang; Zheng, Youqu; Li, Guoneng; Suo, Yange; Chen, Yaping

    2016-01-01

    Highlights: • The novel cothHXf with circumferential overlap and folded baffles is first proposed. • The key sections of cylindrical and dumbbell are constructed to analyze local flow field characteristics. • The restricted leakage, easier to install and low resistant characteristics are emphasized. • The enhanced heat transfer mechanism of Dean Vortex secondary flow is analyzed. • A variety of comprehensive efficiency assessments are used. - Abstract: An efficient and low resistant circumferential overlap trisection helical baffle shell-and-tube heat exchanger with folded baffles (cothHXf) is presented. It is a modified trisection helical baffle heat exchanger with folded helical baffles for setting rods-and-spanning sleeves. It not only inherits all the merits of circumferential overlap helical baffle scheme, but also adds many additional advantages, such as supporting the inclined baffles with the least rods, simplifying the manufacturing process of spanning tubes and effectively inhibiting the reverse leakage at triangular areas between adjacent baffles. The improved flow characteristic and heat transfer enhancement mechanism of this heat exchanger were numerically investigated in comparison with conventional segmental baffles shell-and-tube heat exchanger (segHX). The flow fields within triangular area of adjacent baffles and nearby regions were depicted. The impacts of the folded baffles on shell-side helical flow, secondary vortex flow, and leakage pattern were analyzed. The distribution configurations of fields of velocity, pressure, temperature and local heat flow rate were revealed. The results show that the heat transfer performance and comprehensive performance evaluation indexes of the cothHXf are much better than those of the segHX while the pressure drop of the cothHXf is much lower than that of the segHX. The numerical simulation results of vivid distributions of flow and thermal fields of the cothHXf can provide theoretical basis for an

  17. Single stage circumferential lingual mucosal graft urethroplasty in near obliterative bulbar urethra stricture: A novel technique

    Directory of Open Access Journals (Sweden)

    Umesh Sharma

    2016-01-01

    Full Text Available Aims: This is a prospective study of the use and efficacy of a novel technique of circumferential tubularised lingual mucosal graft (LMG in obliterative and near obliterative bulbar urethral stricture of >2 cm where excisional and augmented anastomotic urethroplasty are not feasible. Materials and Methods: The stenotic urethral segment was opened dorsally in midline and fibrosed urethra was excised taking care to preserve the healthy spongiosum tissue. LMG (av. Length 3 cm was placed from one end of corporal body towards spongy tissue in a circumferential manner. Another LMG was placed in similar manner to deal with longer stricture. The urethra was tubularised over 14 Fr silicone catheter. Results: A total of 12 men, of mean age 47 years underwent this procedure. The mean follow up period was 11 months starting from July 2014 till manuscript submission. Follow up included voiding cystourethrogram at 3 weeks, cystoscopy at 3 months (one patient didn't turned up and subsequent follow up. Mean stricture length was 4.66 cm (range, 3–8.5 cm and mean operative time was 195 min. (range, 160 to 200 min.. The technique was successful (normal voiding with no need for any post-operative procedure in 11(91.6% patients. One patient developed early recurrence at 4 month of surgery and had anastomotic stricture which was successfully managed by direct visual internal urethrotomy. Conclusion: Single stage circumferential tubularised graft urethroplasty is an excellent technique for strictures that include segments of obliterative and near obliterative diseased urethra. It provide a wider neourethra than patch graft urethroplasty.

  18. Soft Tissue Reconstruction of Complete Circumferential Defects of the Upper Extremity

    Directory of Open Access Journals (Sweden)

    Zhi Yang Ng

    2017-03-01

    Full Text Available BackgroundUpper extremity soft tissue defects with complete circumferential involvement are not common. Coupled with the unique anatomy of the upper extremity, the underlying etiology of such circumferential soft tissue defects represent additional reconstructive challenges that require treatment to be tailored to both the patient and the wound. The aim of this study is to review the various options for soft tissue reconstruction of complete circumferential defects in the upper extremity.MethodsA literature review of PubMed and MEDLINE up to December 2016 was performed. The current study focuses on forearm and arm defects from the level at or proximal to the wrist and were assessed based on Tajima's classification (J Trauma 1974. Data reviewed for analysis included patient demographics, causality, defect size, reconstructive technique(s employed, and postoperative follow-up and functional outcomes (when available.ResultsIn accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, 14 unique articles were identified for a total of 50 patients (mean=28.1 years. Underlying etiologies varied from extensive thermal or electrical burns to high impact trauma leading to degloving or avulsion, crush injuries, or even occur iatrogenically after tumor extirpation or extensive debridement. Treatment options ranged from the application of negative pressure wound dressings to the opposite end of the spectrum in hand transplantation.ConclusionsWith the evolution of reconstructive techniques over time, the extent of functional and aesthetic rehabilitation of these complex upper extremity injuries has also improved. The proposed management algorithm comprehensively addresses the inherent challenges associated with these complex cases.

  19. Interaction of thermal stress with mechanical stress in circumferentially cracked pipe

    International Nuclear Information System (INIS)

    Song, Tae Kwang; Kim, Yun Jae; Oh, Chang Kyun

    2008-01-01

    For the cracked component under combined primary and secondary stress, an interacion between the loads occurs and the secondary stress is relaxed by the primary load. To account for this phenomena, R6 code provides the correction factor which is called V-factor. However, evaluation corrected with V-factor need to be examined for its conservatism. In this paper the conservatism of the current V-factor is examined for the circumferentially cracked pipe under the combined load and new evaluation method is proposed to reduce the conservatism

  20. Circumferential skin folds in a child: A case of Michelin tire baby syndrome

    Directory of Open Access Journals (Sweden)

    Palit Aparna

    2007-01-01

    Full Text Available A six-month-old girl who presented with dermatitis was found to have multiple, symmetric, deep, gyrate skin folds involving her trunk and similar circumferential lesions on her extremities since birth. She had a characteristic round face with hypertelorism, depressed nasal bridge, thin, down-turned vermillion border of upper lip and short neck. Skin biopsy demonstrated increased smooth muscle fibers in the deeper dermis. A diagnosis of Michelin tire baby syndrome was made. Clinical features, histopathology, differential diagnosis and prognosis of this rare disorder have been discussed.

  1. Instability predictions for circumferentially cracked Type-304 stainless-steel pipes under dynamic loading. Final report

    International Nuclear Information System (INIS)

    Zahoor, A.; Wilkowski, G.; Abou-Sayed, I.; Marschall, C.; Broek, D.; Sampath, S.; Rhee, H.; Ahmad, J.

    1982-04-01

    This report provides methods to predict margins of safety for circumferentially cracked Type 304 stainless steel pipes subjected to applied bending loads. An integrated combination of experimentation and analysis research was pursued. Two types of experiments were performed: (1) laboratory-scale tests on center-cracked panels and bend specimens to establish the basic mechanical and fracture properties of Type 304 stainless steel, and (2) full-scale pipe fracture tests under quasi-static and dynamic loadings to assess the analysis procedures. Analyses were based upon the simple plastic collapse criterion, a J-estimation procedure, and elastic-plastic large-deformation finite element models

  2. Failure maps for internally pressurized Zr-2.5% Nb pressure tubes with circumferential temperature variations

    International Nuclear Information System (INIS)

    Shewfelt, R.S.W.

    1986-01-01

    During some postulated loss-of-coolant accidents, the pressure tube temperature may rise before the internal pressure drops, causing the pressure tube to balloon. The temperature around the pressure tube circumference would likely be nonuniform, producing localized deformation that could possibly cause failure. The computer program, GRAD, was used to determine the circumferential temperature distribution required to cause an internally pressurized Zr-2.5% Nb pressure tube to fail before coming into full contact with its calandria tube. These results were used to construct failure maps. 7 refs

  3. AMPTRACT: an algebraic model for computing pressure tube circumferential and steam temperature transients under stratified channel coolant conditions

    International Nuclear Information System (INIS)

    Gulshani, P.; So, C.B.

    1986-10-01

    In a number of postulated accident scenarios in a CANDU reactor, some of the horizontal fuel channels are predicted to experience periods of stratified channel coolant condition which can lead to a circumferential temperature gradient around the pressure tube. To study pressure tube strain and integrity under stratified flow channel conditions, it is, necessary to determine the pressure tube circumferential temperature distribution. This paper presents an algebraic model, called AMPTRACT (Algebraic Model for Pressure Tube TRAnsient Circumferential Temperature), developed to give the transient temperature distribution in a closed form. AMPTRACT models the following modes of heat transfer: radiation from the outermost elements to the pressure tube and from the pressure to calandria tube, convection between the fuel elements and the pressure tube and superheated steam, and circumferential conduction from the exposed to submerged part of the pressure tube. An iterative procedure is used to solve the mass and energy equations in closed form for axial steam and fuel-sheath transient temperature distributions. The one-dimensional conduction equation is then solved to obtain the pressure tube circumferential transient temperature distribution in a cosine series expansion. In the limit of large times and in the absence of convection and radiation to the calandria tube, the predicted pressure tube temperature distribution reduces identically to a parabolic profile. In this limit, however, radiation cannot be ignored because the temperatures are generally high. Convection and radiation tend to flatten the parabolic distribution

  4. Determination of the axial and circumferential mechanical properties of the skin tissue using experimental testing and constitutive modeling.

    Science.gov (United States)

    Karimi, Alireza; Navidbakhsh, Mahdi; Haghighatnama, Maedeh; Haghi, Afsaneh Motevalli

    2015-01-01

    The skin, being a multi-layered material, is responsible for protecting the human body from the mechanical, bacterial, and viral insults. The skin tissue may display different mechanical properties according to the anatomical locations of a body. However, these mechanical properties in different anatomical regions and at different loading directions (axial and circumferential) of the mice body to date have not been determined. In this study, the axial and circumferential loads were imposed on the mice skin samples. The elastic modulus and maximum stress of the skin tissues were measured before the failure occurred. The nonlinear mechanical behavior of the skin tissues was also computationally investigated through a suitable constitutive equation. Hyperelastic material model was calibrated using the experimental data. Regardless of the anatomic locations of the mice body, the results revealed significantly different mechanical properties in the axial and circumferential directions and, consequently, the mice skin tissue behaves like a pure anisotropic material. The highest elastic modulus was observed in the back skin under the circumferential direction (6.67 MPa), while the lowest one was seen in the abdomen skin under circumferential loading (0.80 MPa). The Ogden material model was narrowly captured the nonlinear mechanical response of the skin at different loading directions. The results help to understand the isotropic/anisotropic mechanical behavior of the skin tissue at different anatomical locations. They also have implications for a diversity of disciplines, i.e., dermatology, cosmetics industry, clinical decision making, and clinical intervention.

  5. 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.

  6. 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.

  7. 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.

  8. Risk factors of circumferential resection margin involvement in the patients with extraperitoneal rectal cancer.

    Science.gov (United States)

    Oh, Sung Jin; Shin, Jin Yong

    2012-03-01

    Currently, circumferential resection margins (CRM) are used as a clinical endpoint in studies on the prognosis of rectal cancer. Although the concept of a circumferential resection margin in extraperitoneal rectal cancer differs from that in intraperitoneal rectal cancer due to differences in anatomical and biologic behaviors, previous reports have provided information on CRM involvement in all types of rectal cancer including intraperitoneal lesions. Therefore, the aim of this study was to analyze risk factors of CRM involvement in extraperitoneal rectal cancer. From January 2005 to December 2008, 306 patients with extraperitoneal rectal cancer were enrolled in a prospectively collected database. Multivariate logistic regression analysis was used to identify predictors of CRM involvement. The overall rate of CRM involvement was found to be 16.0%. Multivariate analysis showed that male sex, larger tumor size (≥4 cm), stage higher than T3, nodal metastasis, tumor perforation and non-sphincter preserving proctectomy (NSPP) were risk factors for CRM involvement. Male sex, larger tumor size (≥4 cm), advanced T stage, nodal metastasis, tumor perforation, and NSPP are significant risk factors of CRM involvement in extraperitoneal rectal cancer. Given that postoperative chemoradiotherapy is recommended for patients with a positive CRM, further oncologic studies are warranted to ascertain which patients with these risk factors would require adjuvant therapy.

  9. Experimental verification on limit load estimation method for pipes with an arbitrary shaped circumferential surface flaw

    International Nuclear Information System (INIS)

    Li, Yinsheng; Hasegawa, Kunio; Miura, Naoki; Hoshino, Katsuaki

    2010-01-01

    When a flaw is detected in stainless steel pipes during in-service inspection, the limit load criterion given in the codes such as JSME Rules on Fitness-for-Service for Nuclear Power Plants or ASME Boiler and Pressure Vessel Code Section XI can be applied to evaluate the integrity of the pipe. However, in these codes, the limit load criterion is only provided for pipes containing a flaw with uniform depth, although many flaws with complicated shape such as stress corrosion cracking have been actually detected in pipes. In order to evaluate the integrity of the flawed pipes for general case, a limit load estimation method has been proposed by authors considering a circumferential surface flaw with arbitrary shape. The plastic collapse bending moment and corresponding stress are obtained by dividing the surface flaw into several segmented sub-flaws. In this paper, the proposed method was verified by comparing with experimental results. Four-point bending experiments were carried out for full scale stainless steel pipes with a symmetrical or non-symmetrical circumferential flaw. Estimated failure bending moments by the proposed method were found to be in good agreement with the experimental results, and the proposed method was confirmed to be effective for evaluating bending failure of pipes with flaw. (author)

  10. Elastic-plastic finite element analyses for reducers with constant-depth internal circumferential surface cracks

    International Nuclear Information System (INIS)

    Wu, Szu-Ying; Tsai, Bor-Jiun; Chen, Jien-Jong

    2015-01-01

    In this study, a 3-D automatic elastic-plastic finite element mesh generator is established to accurately predict the J-integral value of an arbitrary reducer with a constant-depth internal circumferential surface crack under bending and axial force. The contact pairs are used on the crack surfaces to simulate the actual contact behaviors of the crack model under loadings. In order to verify the accuracy of the proposed elastic-plastic finite element model for a reducer with a surface crack, the cracked straight pipe models are generated according to a special modeling procedure for a flawed reducer. The J-integral values along the crack front of surface crack are calculated and compared with the straight pipe models which have been verified in the previous published studies. Based on the comparison of computed results, good agreements are obtained to show the accuracy of present numerical models. More confidence on using the 3-D elastic-plastic finite element analysis for reducers with internal circumferential surface cracks can be thus established in this work

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

    International Nuclear Information System (INIS)

    Kilinski, T.; Mohan, R.; Rudland, D.; Fleming, M.

    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

  12. Circumferential scouting punch biopsies to delineate surgical margin for dermatofibrosarcoma protuberans

    Directory of Open Access Journals (Sweden)

    Tsung-Mao Huang

    2012-03-01

    Full Text Available Dermatofibrosarcoma protuberans (DFSP is an uncommon soft-tissue tumor involving the dermis and subcutaneous tissue with a high local recurrence rate after standard excision. Mohs micrographic surgery offers a lower recurrence rate. However, the procedure requires multiple stages of excision with intraoperative histopathological mapping, which is time consuming and expensive. We report our experience of using circumferential scouting punch biopsy technique in five patients to determine in advance the resection margins for DFSP prior to wide excision. Multiple 4 mm punches, usually eight in number, were performed 1–2.5 cm around the palpable borders of DFSP to delineate the resection margins in five consecutive patients. Tumors were excised at a later date along the margin defined by these biopsies and the wounds were repaired with skin graft. The operation was completed in 2 hours in all cases excluding one that required frozen sections for deep margin. No recurrence was noted 2–10 years after the operations. The results suggest that circumferential scouting punch biopsies before wide excision may be an alternative method to define the resection margins for DFSP when Mohs surgery is not available.

  13. Design and control of a novel gastroscope intervention mechanism with circumferentially pneumatic-driven clamping function.

    Science.gov (United States)

    Li, Yanmin; Liu, Hao; Hao, Siwen; Li, Hongyi; Han, Jianda; Yang, Yunsheng

    2017-03-01

    Robot-assisted manipulation is promising for solving problems such as understaffing and the risk of infection in gastro-intestinal endoscopy. However, the commonly used friction rollers in few existing systems have a potential risk of deforming flexible endoscopes for non-uniform clamping. This paper presents a robotic system for a standard flexible endoscope and focuses on a novel gastroscope intervention mechanism (GIM), which provides circumferentially uniform clamping with an airbag. The GIM works with a relay-on mechanism in a way similar to manual operation. The shear stiffness of airbag and the critical slipping force (CSF) were analysed to determine the parameters of the airbag. A fuzzy PID controller was employed to realize a fast response and high accuracy of pneumatic actuation. Experiments were performed to evaluate the accuracy, stiffness and CSF. In vitro and in vivo animal experiments were also carried out. The GIM realized an accuracy of 0.025 ± 0.2 mm and -0.03 ± 0.25° for push-pull and rotation without delivery resistance. Under polynomial could be used to describe the relationship between the CSF and pneumatic pressure. The novel GIM could effectively deliver gastroscopes. The pneumatic-driven clamping method proposed could protect the gastroscope by circumferentially uniform clamping force and the CSF could be properly controlled to guarantee operating safety. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  14. 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.

  15. 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.

  16. Elastic-Plastic Fracture Mechanics Analyses for Circumferential Part-Through Surface Cracks at the Interface Between elbows and Pipes

    International Nuclear Information System (INIS)

    Song, Tae Kwang; Oh, Chang Kyun; Kim, Yun Jae; Kim, Jong Sung; Jin, Tae Eun

    2007-01-01

    This paper presents plastic limit loads and approximate J-integral estimates for circumferential part-through surface crack at the interface between elbows and pipes. Based on finite element limit analyses using elastic-perfectly plastic materials, plastic limit moments under in-plane bending are obtained and it is found that they are similar those for circumferential part-through surface cracks in the center of elbow. Based on present FE results, closed-form limit load solutions are proposed. Welds are not explicitly considered and all materials are assumed to be homogeneous. And the method to estimate the elastic-plastic J-integral for circumferential part-through surface cracks at the interface between elbows and straight pipes is proposed based on the reference stress approach, which was compared with corresponding solutions for straight pipes

  17. Elastic-Plastic Fracture Mechanics Analyses For circumferential Part-through Surface Cracks At The Interface Between Elbows and Pipes

    International Nuclear Information System (INIS)

    Song, Tae Kwang; Kim, Yun Jae; Oh, Chang Kyun; Kim, Jong Sung; Jin, Tae Eun

    2007-01-01

    This paper presents plastic limit loads and approximate J-integral estimates for circumferential part-through surface crack at the interface between elbows and pipes. Based on finite element limit analyses using elastic-perfectly plastic materials, plastic limit moments under in-plane bending are obtained and it is found that they are similar those for circumferential part-through surface cracks in the center of elbow. Based on present FE results, closed-form limit load solutions are proposed. Welds are not explicitly considered and all materials are assumed to be homogeneous. And the method to estimate the elastic-plastic J-integral for circumferential part-through surface cracks at the interface between elbows and straight pipes is proposed based on the reference stress approach, which was compared with corresponding solutions for straight pipes

  18. Plastic fracture mechanics prediction of fracture instability in a circumferentially cracked pipe in bending--1. J-integral analysis

    International Nuclear Information System (INIS)

    Zahoor, A.; Kanninen, M.F.

    1980-01-01

    A method of evaluating the J-integral for a circumferentially cracked pipe in bending is proposed. The method allows a J-resistance curve to be evaluated directly from the load-displacement record obtained in a pipe fracture experiment. This method also permits an analysis for fracture instability in a circumferential crack growth using a J-resistance curve and the tearing modulus parameter. The importance of using a J-resistance curve that is consistent with the type of constraint for a given application is emphasized. 18 refs

  19. Corrosion degradation of steam generators in Korea

    International Nuclear Information System (INIS)

    Hwang, Seong Sik; Kim, Hong Pyo; Kim, Joung Soo

    2003-01-01

    Six pull tube examinations from Korean nuclear power plants have been carried out by Korea atomic energy research institute (KAERI) and some foreign laboratories since the first commercial operation of Kori unit 1 in 1978. A total of 15 tubes were extracted that exhibited different types of failures such as pitting, outer diameter stress corrosion cracking (ODSCC), primary water stress corrosion cracking (PWSCC), intergranular attack (IGA), etc. Pitting of plant A was related with the high copper dissolved from condenser material, Cl- and high dissolved oxygen. Transgranular SCC of plant B seemed to be related to the lead compound. ODSCC and IGA in plant A were connected with caustic environments in the crevices. PWSCC in plant A and plant C originated from the inherent characteristics of the materials, which were not properly thermally treated. After the failure analyses, a performance of nondestructive testing was evaluated based on the destructive metallographic examination, and some counter measures such as material change, inhibitor injection, molar ratio control, and temperature reduction operation were suggested. (author)

  20. Transient Stress Intensity Factors of Functionally Graded Hollow Cylinders with Internal Circumferential Cracks

    Directory of Open Access Journals (Sweden)

    Iman Eshraghi

    Full Text Available Abstract In this paper, transient thermomechanical stress intensity factors for functionally graded cylinders with complete internal circumferential cracks are obtained using the weight function method. The finite difference method is used to calculate the time dependent temperature distribution and thermal stresses along the cylinder thickness. Furthermore, finite element analysis is performed to determine the weight function coefficients and to investigate the accuracy of the predicted stress intensity factors from the weight functions. Variation of the stress intensity factors with time and effects of the material gradation on the results are investigated, as well. It is shown that the proposed technique can be used to accurately predict transient thermomechanical stress intensity factors for functionally graded cylinders with arbitrary material gradation.

  1. Failure behaviour of a piping system with a circumferentially orientated flaw

    International Nuclear Information System (INIS)

    Mikkola, T.P.J.; Diem, H.; Blind, D.; Hunger, H.

    1987-01-01

    The experiments were conducted on the recently installed feedwater line of the HDR reactor in Kahl. The investigations were focused on analysing both the crack propagation of a circumferentially flowed pipe under the influence of corrosion and cyclic load, together with the pipeline's subsequent failure behaviour. The experimental conditions were selected in a manner representing those which can, for example, prevait during start-up or shut-down of reactor. To this aim, the pipes were internally stressed with high pressure and temperature oxygenic water in conjunction with an externally applied bending moment. The investigations are supplemented by elastic-plastic triaxial finite element (FE) calculations for various assumed crack configurations, both prior to and following the experiments, thus granting a fracture-mechanical assessment of the structural behaviour. (orig./DG) [de

  2. Failure behavior of a pipe system with a circumferentially orientated flaw - analytical and experimental investigations

    International Nuclear Information System (INIS)

    Mikkola, T.P.J.; Diem, H.; Blind, D.; Hunger, H.

    1989-01-01

    At the german HDR-test-facility a pipe failure experiment was performed at a fullsize feedwater piping system under operating conditions of T=240 0 C, p=10.6 MPa and with an elevated oxygen content in the pressure medium. The loading was internal pressure and a cyclic varying bending moment with an R-ratio of 0.5. The in form of a circumferentially orientated notch initially weakened piping system failed after a total number of 4773 loaded cycles with different frequencies in form of a small leak. The analyses of the fracture surface indicated the strongly growing influence of corrosion effects on the crack propagation rate with decreasing loading frequency. The cyclic crack growth and the leak-before-break behavior of the piping system could be explained on the basis of results of finite element calculations using ADINA-code. (orig.)

  3. Enhancement of J estimation for typical nuclear pipes with a circumferential surface crack under tensile load

    International Nuclear Information System (INIS)

    Cho, Doo Ho; Woo, Seung Wan; Choi, Jae Boong; Kim, Young Jin; Chang, Yoon Suk; Jhung, Myung Jo; Choi, Young Hwan

    2010-01-01

    This paper is to report enhancement of engineering J estimation for semi-elliptical surface cracks under tensile load. Firstly, limitation of the sole solution suggested by Zahoor is shown for reliable structural integrity assessment of thin-walled nuclear pipes. An improved solution is then developed based on extensive 3D FE analyses employing deformation plasticity theory for typical nuclear piping materials. It takes over the structure of the existing solution but provides new tabulated plastic influence functions to cover a wide range of pipe geometry and crack shape. Furthermore, to facilitate easy prediction of the plastic influence function, an alternative simple equation is also developed by using a statistical response surface method. The proposed H 1 values can be used for elastic-plastic fracture analyses of thin-walled pipes with a circumferential surface crack subjected to tensile loading

  4. Enhancement of J estimation for typical nuclear pipes with a circumferential surface crack under tensile load

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Doo Ho; Woo, Seung Wan; Choi, Jae Boong; Kim, Young Jin [Sungkyunkwan University, Suwon (Korea, Republic of); Chang, Yoon Suk [Kyung Hee University, Yongin (Korea, Republic of); Jhung, Myung Jo; Choi, Young Hwan [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2010-03-15

    This paper is to report enhancement of engineering J estimation for semi-elliptical surface cracks under tensile load. Firstly, limitation of the sole solution suggested by Zahoor is shown for reliable structural integrity assessment of thin-walled nuclear pipes. An improved solution is then developed based on extensive 3D FE analyses employing deformation plasticity theory for typical nuclear piping materials. It takes over the structure of the existing solution but provides new tabulated plastic influence functions to cover a wide range of pipe geometry and crack shape. Furthermore, to facilitate easy prediction of the plastic influence function, an alternative simple equation is also developed by using a statistical response surface method. The proposed H{sub 1} values can be used for elastic-plastic fracture analyses of thin-walled pipes with a circumferential surface crack subjected to tensile loading

  5. A Steel Ball Surface Quality Inspection Method Based on a Circumferential Eddy Current Array Sensor.

    Science.gov (United States)

    Zhang, Huayu; Xie, Fengqin; Cao, Maoyong; Zhong, Mingming

    2017-07-01

    To efficiently inspect surface defects on steel ball bearings, a new method based on a circumferential eddy current array (CECA) sensor was proposed here. The best probe configuration, in terms of the coil quality factor (Q-factor), magnetic field intensity, and induced eddy current density on the surface of a sample steel ball, was determined using 3-, 4-, 5-, and 6-coil probes, for analysis and comparison. The optimal lift-off from the measured steel ball, the number of probe coils, and the frequency of excitation current suitable for steel ball inspection were obtained. Using the resulting CECA sensor to inspect 46,126 steel balls showed a miss rate of ~0.02%. The sensor was inspected for surface defects as small as 0.05 mm in width and 0.1 mm in depth.

  6. Time displacement pictures with multi-mode probes from circumferential welds

    International Nuclear Information System (INIS)

    Wustenberg, H.; Jaffrey, D.; Ludwig, B.; Bertus, N.; Erhard, A.

    1985-01-01

    If a creeping wave probe is applied to butt welds typical echo patterns from weld defects can be received. It seems possible that echoes from the geometric shape of the root or the crown and defect echoes can be separated by simple means. This has been the reason for the development of a special presentation of the echo patterns received by this multi-mode creeping wave probe. The so called time displacement pictures show the AD-converted A-scans in a gray scale along a line corresponding to the time axis of the propagation. Perpendicular to this time axis results obtained from displacement of the probe parallel to the weld are presented. This kind of picture immediately provides the whole A-scan information. This paper presents some first results on simulated welds with artificial defects and on circumferential welds with typical geometric imperfections

  7. Cut-off frequencies of circumferential horizontal shear waves in various functionally graded cylinder shells.

    Science.gov (United States)

    Shen, Xiaoqin; Ren, Dawei; Cao, Xiaoshan; Wang, Ji

    2018-03-01

    In this study, cut-off frequencies of the circumferential SH waves in functionally graded piezoelectric-piezomagnetic material (FGPPM) cylinder shells with traction free, electrical and magnetic open boundary conditions are investigated analytically. The Wentzel-Kramers-Brillouin (WKB) method is employed for solving differential equations with variable coefficients for general cases. For comparison, Bessel functions and Kummer functions are used for solving cut-off frequency problems in homogenous and ideal FGPPM cylinder shells. It is shown that the WKB solution for the cut-off frequencies has good precise. The set of cut-off frequencies is a series of approximate arithmetic progressions, for which the difference is a function of the density and the effective elastic parameter. The relationship between the difference and the gradient coefficient is described. These results provide theoretical guidance for the non-destructive evaluation of curved shells based on the cut-off frequencies. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. 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.

  9. Stress intensity magnification factors for fully circumferential cracks in valve bodies (thick cylinders)

    International Nuclear Information System (INIS)

    Toor, P.M.

    1998-01-01

    The stress intensity solutions presented herein were obtained using an energy method in conjunction with a two-dimensional finite element program in order to explicitly account for curvature effect for fully circumferential cracks. The magnification factors for a specific crack depth were calculated by successively loading the crack surface by a uniform, linear, quadratic, and a cubic loading distribution. The magnification factors can be used to calculate the stress intensity factors by superposition method. The functions for each load condition in terms of radius to thickness ratio (R/t) and a fractional distance in terms of crack depth to thickness ratio (a/t) were developed. The validity of these functions is R/t = 1.5 to 10.0 and for 0.0125 ≤ a/t ≤ 0.8125. The functions agree to within 1% of the finite elements solutions for most magnification factors

  10. Ductile fracture of circumferentially cracked type-304 stainless steel pipes in tension

    Energy Technology Data Exchange (ETDEWEB)

    Zahoor, A.; Norris, D.M.

    1984-11-01

    Circumferentially cracked pipes subjected to tensile load were analyzed for finite length and constant depth part-through cracks located at the inside of the pipe wall. The analysis postulated loads sufficient to cause net-section yielding of the flawed section. It was demonstrated that a propensity for predominantly radial growth exists for part-through cracks loaded in tension. This result is similar to the result for bend loading, except that bend loading causes more favorable conditions for wall breakthrough than tension loading. Numerical results were developed for 4-in. and 24-in-dia pipes. Safety margins for displacement controlled loads were described by a safety assessment diagram. This diagram defines a curve delineating leak from fracture in a space of nondimensional crack length and crack depth. 4-india schedule 80 Type-304 stainless steel pipes with length to radius ratio (L/R) of up to 100 exhibited leak-before-break behavior.

  11. Ductile fracture of circumferentially cracked type-304 stainless steel pipes in tension

    International Nuclear Information System (INIS)

    Zahoor, A.; Norris, D.M.

    1984-01-01

    Circumferentially cracked pipes subjected to tensile load were analyzed for finite length and constant depth part-through cracks located at the inside of the pipe wall. The analysis postulated loads sufficient to cause net-section yielding of the flawed section. It was demonstrated that a propensity for predominantly radial growth exists for part-through cracks loaded in tension. This result is similar to the result for bend loading, except that bend loading causes more favorable conditions for wall breakthrough than tension loading. Numerical results were developed for 4-in. and 24-in-dia pipes. Safety margins for displacement controlled loads were described by a safety assessment diagram. This diagram defines a curve delineating leak from fracture in a space of nondimensional crack length and crack depth. 4-india schedule 80 Type-304 stainless steel pipes with length to radius ratio (L/R) of up to 100 exhibited leak-before-break behavior

  12. A Steel Ball Surface Quality Inspection Method Based on a Circumferential Eddy Current Array Sensor

    Directory of Open Access Journals (Sweden)

    Huayu Zhang

    2017-07-01

    Full Text Available To efficiently inspect surface defects on steel ball bearings, a new method based on a circumferential eddy current array (CECA sensor was proposed here. The best probe configuration, in terms of the coil quality factor (Q-factor, magnetic field intensity, and induced eddy current density on the surface of a sample steel ball, was determined using 3-, 4-, 5-, and 6-coil probes, for analysis and comparison. The optimal lift-off from the measured steel ball, the number of probe coils, and the frequency of excitation current suitable for steel ball inspection were obtained. Using the resulting CECA sensor to inspect 46,126 steel balls showed a miss rate of ~0.02%. The sensor was inspected for surface defects as small as 0.05 mm in width and 0.1 mm in depth.

  13. Fracture toughness evaluation using circumferential notched tensile specimens by the tensile test and ANSYS software

    Energy Technology Data Exchange (ETDEWEB)

    Meydanlik, N. [Mechanical Engineering Department, Trakya University, Edirne (Turkey)

    2013-07-01

    Fracture toughness (K{sub Ic} ) is the most important parameter that defines mechanical behaviour of the materials using machine design. Since, fracture tests are both difficult and time consuming, the researchers have been investigating for the easier evaluation of K{sub Ic} for many years. In this work; K{sub Ic} values have been obtained by using ANSYS software based on the experimental values evaluated in the previous studies. It was shown that there is no significant difference between the experimental ones and the ones obtained by ANSYS. This procedure can provide an important advantage on obtaining of the K{sub IC} values. Key words: Fracture toughness (K{sub Ic} ), circumferential notched tensile specimens, ANSYS.

  14. Circumferential nonuniformity of cladding radiation swelling of fast reactor peripheral fuel elements

    International Nuclear Information System (INIS)

    Reutov, V.F.; Farkhutdinov, K.G.

    1977-01-01

    The results are presented of the investigation into the perimeter radiation swelling of Kh18N10T stainless steel cladding in different cross sections of a peripheral fuel element of the BR-5 reactor. The fluence on the cladding is 1.8-2.9 x 10 22 fast neutr/cm 2 , the operating temperatures in different parts of the fuel element being 430 deg to 585 deg C. There has been observed circumferential non-uniformity of the distribution, concentration, and of the total volume of radiation cavities, which is due to temperature non-uniformity along the cladding perimeter. It is shown that such non-uniformity of radiation swelling of the cladding material may result in bending of the peripheral fuel element with regard to the fuel assembly sheath walls

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

    Science.gov (United States)

    Barret, Maximilien; Pratico, Carlos Alberto; Camus, Marine; Beuvon, Frédéric; Jarraya, Mohamed; Nicco, Carole; Mangialavori, Luigi; Chaussade, Stanislas; Batteux, Frédéric; Prat, Frédéric

    2014-01-01

    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.

  16. 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.

  17. 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.

  18. Deficient Circumferential Growth Is the Primary Determinant of Aortic Obstruction Attributable to Partial Elastin Deficiency.

    Science.gov (United States)

    Jiao, Yang; Li, Guangxin; Korneva, Arina; Caulk, Alexander W; Qin, Lingfeng; Bersi, Matthew R; Li, Qingle; Li, Wei; Mecham, Robert P; Humphrey, Jay D; Tellides, George

    2017-05-01

    Williams syndrome is characterized by obstructive aortopathy attributable to heterozygous loss of ELN , the gene encoding elastin. Lesions are thought to result primarily from excessive smooth muscle cell (SMC) proliferation and consequent medial expansion, although an initially smaller caliber and increased stiffness of the aorta may contribute to luminal narrowing. The relative contributions of such abnormalities to the obstructive phenotype had not been defined. We quantified determinants of luminal stenosis in thoracic aortas of Eln -/- mice incompletely rescued by human ELN . Moderate obstruction was largely because of deficient circumferential growth, most prominently of ascending segments, despite increased axial growth. Medial thickening was evident in these smaller diameter elastin-deficient aortas, with medial area similar to that of larger diameter control aortas. There was no difference in cross-sectional SMC number between mutant and wild-type genotypes at multiple stages of postnatal development. Decreased elastin content was associated with medial fibrosis and reduced aortic distensibility because of increased structural stiffness but preserved material stiffness. Elastin-deficient SMCs exhibited greater contractile-to-proliferative phenotypic modulation in vitro than in vivo. We confirmed increased medial collagen without evidence of increased medial area or SMC number in a small ascending aorta with thickened media of a Williams syndrome subject. Deficient circumferential growth is the predominant mechanism for moderate obstructive aortic disease resulting from partial elastin deficiency. Our findings suggest that diverse aortic manifestations in Williams syndrome result from graded elastin content, and SMC hyperplasia causing medial expansion requires additional elastin loss superimposed on ELN haploinsufficiency. © 2017 American Heart Association, Inc.

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

    International Nuclear Information System (INIS)

    Choi, Joon Young; Lee, Kyung Han; Kim, Sang Eun; Kim, Byung Tae; Hwang, Jee Hea; Lee, Byung Boong

    1997-01-01

    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

  20. 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....

  1. The Influence of Hospital Volume on Circumferential Resection Margin Involvement: Results of the Dutch Surgical Colorectal Audit

    NARCIS (Netherlands)

    Gietelink, Lieke; Henneman, Daniel; van Leersum, Nicoline J.; de Noo, Mirre; Manusama, Eric; Tanis, Pieter J.; Tollenaar, Rob A. E. M.; Wouters, Michel W. J. M.

    2016-01-01

    This population-based study evaluates the association between hospital volume and CRM (circumferential resection margin) involvement, adjusted for other confounders, in rectal cancer surgery. A low hospital volume ( <20 cases/year) was independently associated with a higher risk of CRM involvement

  2. Net-section limit moments and approximate J estimates for circumferential cracks at the interface between elbows and pipes

    International Nuclear Information System (INIS)

    Song, Tae-Kwang; Kim, Yun-Jae; Oh, Chang-Kyun; Jin, Tae-Eun; Kim, Jong-Sung

    2009-01-01

    This paper firstly presents net-section limit moments for circumferential through-wall and part-through surface cracks at the interface between elbows and attached straight pipes under in-plane bending. Closed-form solutions are proposed based on fitting results from small strain FE limit analyses using elastic-perfectly plastic materials. Net-section limit moments for circumferential cracks at the interface between elbows and attached straight pipes are found to be close to those for cracks in the centre of elbows, implying that the location of the circumferential crack within an elbow has a minimal effect on the net-section limit moment. Accordingly it is also found that the assumption that the crack locates in a straight pipe could significantly overestimate the net-section limit load (and thus maximum load-carrying capacity) of the cracked component. Based on the proposed net-section limit moment, a method to estimate elastic-plastic J based on the reference stress approach is proposed for circumferential cracks at the interface between elbows and attached straight pipes under in-plane bending.

  3. End-systolic stress-velocity relation and circumferential fiber velocity shortening for analysing left ventricular function in mice

    Energy Technology Data Exchange (ETDEWEB)

    Fayssoil, A. [Cardiologie, Hopital europeen Georges Pompidou, 20, rue le blanc, Paris (France)], E-mail: fayssoil2000@yahoo.fr; Renault, G. [CNRS UMR 8104, Inserm, U567, Institut Cochin, Universite Paris Descartes, Paris (France); Fougerousse, F. [Genethon, RD, Evry (France)

    2009-08-15

    Traditionally, analysing left ventricular (LV) performance relies on echocardiography by evaluating shortening fraction (SF) in mice. SF is influenced by load conditions. End-systolic stress-velocity (ESSV) relation and circumferential fiber velocity (VcF) shortening are more relevant parameters for evaluating systolic function regardless load conditions particularly in mice's models of heart failure.

  4. Numerical analysis of flow in a centrifugal compressor with circumferential grooves: influence of groove location and number on flow instability

    Science.gov (United States)

    Chen, X.; Qin, G.; Ai, Z.; Ji, Y.

    2017-08-01

    As an effective and economic method for flow range enhancement, circumferential groove casing treatment (CGCT) is widely used to increase the stall margin of compressors. Different from traditional grooved casing treatments, in which the grooves are always located over the rotor in both axial and radial compressors, one or several circumferential grooves are located along the shroud side of the diffuser passage in this paper. Numerical investigations were conducted to predict the performance of a low flow rate centrifugal compressor with CGCT in diffuser. Computational fluid dynamics (CFD) analysis is performed under stage environment in order to find the optimum location of the circumferential casing groove in consideration of stall margin enhancement and efficiency gain at design point, and the impact of groove number to the effect of this grooved casing treatment configuration in enhancing the stall margin of the compressor stage is studied. The results indicate that the centrifugal compressor with circumferential groove in vaned diffuser can obtain obvious improvement in the stall margin with sacrificing design efficiency a little. Efforts were made to study blade level flow mechanisms to determine how the CGCT impacts the compressor’s stall margin (SM) and performance. The flow structures in the passage, the tip gap, and the grooves as well as their mutual interactions were plotted and analysed.

  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 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. 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...... OF BACKGROUND DATA: The cost-effectiveness of circumferential fusion in a long-term perspective is uncertain but nonetheless highly relevant as the ISSLS prize winner 2006 in clinical studies reported the effect of circumferential fusion superior to the effect of posterolateral fusion. A recent trial found...... no significant difference between posterolateral and circumferential fusion reporting cost-effectiveness from a 2-year viewpoint. METHODS: A total of 146 patients were randomized to posterolateral or circumferential fusion and followed 4 to 8 years after surgery. The mean age of the cohort was 46 years (range...

  7. Finite Element Limit Pressures for Circumferential Through-Wall Cracks in the Interface between Elbow and Pipe

    International Nuclear Information System (INIS)

    Jang, Yoon-Young; Han, Tae-Song; Huh, Nam-Su; Jeong, Jae-Uk

    2014-01-01

    Among integrity assessment method based on a fracture mechanics concept for piping system, a limit load method is one of the important way to predict a maximum load carrying capacity in the materials with high ductility in the sense that it is used to either assess directly structural integrity of pipe based on fully plastic fracture mechanics or calculate elasticplastic fracture mechanics parameters based on reference stress concept. In nuclear power plants, piping system often involves elbows welded to straight pipe. Since welded regions are vulnerable to cracking, it is important to predict an accurate limit load for pipes with a crack in the interface between elbows and attached pipes. However, although extensive works have been made for developing limit analysis methods for cracked pipes, they were mainly for straight pipes. Recently, limit moment solutions for elbow that is attached to straight pipe with a circumferential through-wall crack(TWC) in the interface were proposed, whereas limit pressure for this geometry is not suggested yet. In this context, plastic limit pressures of circumferential TWCs between elbow and straight pipe were calculated in the present study considering geometric parameters such as an elbow curvature, a pipe size and a crack length. In the present study, the FE plastic limit analyses for circumferential TWC in the interface between elbow and pipe under internal pressure were conducted based on elastic perfectly plastic assumption. Based on the present FE results, it is found that plastic limit pressures of straight pipes with circumferential TWC are not appropriate for predicting plastic limit pressures of circumferential TWC in the interface between elbow and pipe for shorter crack length

  8. Influence of circumferential flaw length on internal burst pressure of a wall-thinned pipe

    Energy Technology Data Exchange (ETDEWEB)

    Tsuji, Masataka, E-mail: tsuji-m@u-fukui.ac.jp [Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui, Fukui (Japan); Meshii, Toshiyuki [Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui, Fukui (Japan)

    2013-02-15

    Highlights: ► The effect of θ on p{sub f} was examined by experimental analysis and FEA. ► Here θ is the circumferential angle of a flaw, p{sub f} is the internal burst pressure. ► p{sub f} decreased as θ increased in some cases. ► The effect of θ on p{sub f} should be taken into consideration in evaluating p{sub f}. -- Abstract: This paper examines the effect of the circumferential angle of a flaw θ on the internal burst pressure p{sub f} of pipes with artificial wall-thinned flaws. The effect of θ has conventionally been regarded as unimportant in the evaluation of the p{sub f} of wall-thinned straight pipes. Therefore, a burst pressure equation for an axial crack inside a cylinder (Fig. 1, left), such as Kiefner's equation (Kiefner et al., 1973), has been widely applied (ANSI/ASME B31.G., 1991; Hasegawa et al., 2011). However, the following implicit assumptions notably exist when applying the equation to planar flaws in situations with non-planar flaws. 1)The fracture mode of the non-planar flaw under consideration is identical to that of the crack. 2)The effect of θ on p{sub f}, which is not considered for an axial crack, is small or negligible. However, the experimental results from the systematic burst tests for carbon steel pipes with artificial wall-thinned flaws examined in this paper showed that these implicit assumptions may be incorrect. In this paper the experimental results are evaluated in further detail. The purpose of the evaluation was to clarify the effect of θ on p{sub f}. Specifically, the significance of the flaw configuration (axial length δ{sub z} and wall-thinning ratio t{sub 1}/t) was studied for its effects on θ and p{sub f}. In addition, a simulation of this effect was conducted using a large strain elastic-plastic Finite Element Analysis (FEA) model. As observed from the experimental results, θ tended to affect p{sub f} in cases with large δ{sub z}, and t{sub 1}/t was also correlated with a decrease in p{sub f

  9. The stability of through-wall circumferential cracks in cylindrical pipes subjected to bending loads

    International Nuclear Information System (INIS)

    Smith, E.

    1983-01-01

    Tada, Paris and Gamble have used the tearing modulus approach to show that when a circumferential through-wall crack exists in a 304 SS circular cylindrical pipe, and the pipe is subjected to an applied bending moment, then crack growth requires the rotation at the pipe-ends to be increased, (i.e. crack growth is stable), unless the pipe length is unduly large. On this basis it was concluded that unstable fracture is unlikely to occur in BWR SS piping, when the system is designed in accord with the ASME Code load levels for normal operation and anticipated transients. The Tada-Paris-Gamble analysis focuses on the inter-relation between instability and the onset of crack extension, and does not specifically consider the possibility that a crack might become unstable after some stable crack extension. The paper addresses this aspect of the crack stability problem using a crack tip opening angle criterion for crack extension, which has similarities with the tearing modulus approach. The results show that unstable fracture should not occur even after some stable crack extension, again provided that the pipe length is not unduly large. In other words, guillotine failure of a pipe in a BWR system is unlikely, even though the ASME Code limiting stress levels as might be exceeded, as may be the case with a very severe earthquake. (orig./HP)

  10. Occurrence and prognostic value of circumferential resection margin involvement for patients with rectal cancer.

    Science.gov (United States)

    Wang, Cun; Zhou, Zong-guang; Yu, Yong-yang; Shu, Ye; Li, Yuan; Yang, Lie; Li, Li

    2009-04-01

    Total mesorectal excision (TME) was advocated owning to the reduction in local failure, while deficiency in pathologic details limited monitoring of surgical quality assurance. Here, we aimed to examine circumferential resection margin (CRM) by large tissue slice, discussing its rule in occurrence and relationship with prognosis, thus providing proof for the adoption of TME principles and the application of adjuvant therapy. Specimens of 106 patients with rectal cancer, who underwent potentially curative resection from December 2001 to September 2002, were examined. Follow-up data were collected. Altogether, 2,068 mesorectal nodes were examined with 272 involved by tumor. CRM involvement (CRMI) was examined in 20 specimens. In these 20 cases, seven, nine, and four were caused by tumor infiltration, lymph node metastasis, and both, respectively. Occurrence of CRMI was more common for lower-located cancers while also statistically related to tumor differentiation, infiltration, and lymph node metastasis. The difference in local recurrence rate, general recurrence rate, disease-free survival rate, and overall survival rate between the group with CRMI and the group without were all proven to be significant. Detailed pathologic examination, including status of CRM, is advocated since it provides accurate prognostic information. Surgeons could maximize the probability of cure by following the principle of TME. Preoperative adjuvant therapy was essential for advanced staged and lower-located lesions, which implied likelihood of CRMI.

  11. Optimization of Reinforced Concrete Reservoir with Circumferential Stiffeners Strips by Particle Swarm Algorithm

    Directory of Open Access Journals (Sweden)

    GholamReza Havaei

    2015-09-01

    Full Text Available Reinforced concrete reservoirs (RCR have been used extensively in municipal and industrial facilities for several decades. The design of these structures requires that attention be given not only to strength requirements, but to serviceability requirements as well. These types of structures will be square, round, and oval reinforced concrete structures which may be above, below, or partially below ground. The main challenge is to design concrete liquid containing structures which will resist the extremes of seasonal temperature changes, a variety of loading conditions, and remain liquid tight for useful life of 50 to 60 years. In this study, optimization is performed by particle swarm algorithm basd on structural design. Firstly by structural analysis all range of shell thickness and areas of rebar find. In the second step by parameter identification system interchange algorithm, source code which developed in particle swarm algorithm by MATLAB software linked to analysis software. Therefore best and optimized thicknesses and total area of bars for each element find. Lastly with circumferential stiffeners structure optimize and show 19% decrease in weight of rebar, 20% decrease in volume of concrete, and 13% minimum cost reduction in construction procedure compared with conventional 10,000 m3 RCR structures.

  12. Simplified method of calculating residual stress in circumferential welding of piping

    International Nuclear Information System (INIS)

    Umemoto, Tadahiro

    1984-01-01

    Many circumferential joints of piping are used in as-welded state, but in these welded joints, the residual stress as high as the yield stress of materials arises, and causes to accelerate stress corrosion cracking and corrosion fatigue. The experiment or the finite element method to clarify welding residual stress requires much time and labor, and is expensive, therefore, the author proposed the simplified method of calculation. The heating and cooling process of welding is very complex, and cannot be modeled as it is, therefore, it was assumed that in multiple layer welding, the welding condition of the last layer determines the residual stress, that material constants are invariable regardless of temperature, that the temperature distribution and residual stress are axisymmetric, and that there is repeated stress-strain relation in the vicinity of welded parts. The temperature distribution at the time of welding, thermal stress and welding residual stress are analyzed, and the material constants used for the calculation of residual stress are given. As the example of calculation, the effect of welding heat input and materials is shown. The extension of the method to a thick-walled pipe is discussed. (Kako, I.)

  13. Development of a J-estimation scheme for internal circumferential and axial surface cracks in elbows

    International Nuclear Information System (INIS)

    Mohan, R.; Brust, F.W.; Ghadiali, N.; Wilkowski, G.

    1996-06-01

    This report summarizes efforts to develop elastic and elastic-plastic fracture mechanics analyses for internal surface cracks in elbows. The analyses involved development of a GE/EPRI type J-estimation scheme which requires an elastic and fully plastic contribution to crack-driving force in terms of the J-integral parameter. The elastic analyses require the development of F-function values to relate the J e term to applied loads. Similarly, the fully plastic analyses require the development of h-functions to relate the J p term to the applied loads. The F- and h-functions were determined from a matrix of finite element analyses. To minimize the cost of the analyses, three-dimensional ABAQUS finite element analyses were compared to a simpler finite element technique called the line-spring method. The line-spring method provides a significant computational savings over the full three-dimensional analysis. The comparison showed excellent agreement between the line-spring and three-dimensional analysis. This experience was consistent with comparisons with circumferential surface-crack analyses in straight pipes during the NRC's Short Cracks in Piping and Piping Welds program

  14. Assessment of circumferential cracks in hypereutectic Al-Si clutch housings

    Directory of Open Access Journals (Sweden)

    M. Haghshenas

    2017-04-01

    Full Text Available As in situ natural composites with silicon phase acting as the reinforcing phase, Al-Si alloys are among most commonly used aluminum alloys in automotive applications (i.e. engine component. Silicon contributes to the strength of Al-Si alloys through load transfer from the Al matrix to the hard (rigid Si phase in the microstructure (load-carrying capacity. Casting parameters (i.e. solidification rate, elemental segregation, secondary dendrite spacing… as well as the size and distribution of the microstructural constituents in Al-Si alloys (i.e. morphology of Si particles, intermetallic compounds, secondary dendrite spacing contribute directly to the mechanical response and failure (or fracture behavior of the alloy within the service. In hyper-eutectic Al-Si alloys (i.e. B390.0, distribution of coarse pre-eutectic Si particle mainly contribute to stress concentration, crack initiation and propagation during the actual service condition. In the present paper, the parameters contribution to the formation of the circumferential cracks in clutch housings made of die cast hyper-eutectics B390.0 Al-Si alloys are assessed through optical microscopy and scanning electron microscopy. Casting variable, cooling rate, their effect on the cracks as well some of the possible causes are also discussed in detail.

  15. Ultrasonic phased array examination of circumferential weld joint in reactor pressure vessel of BWR

    Energy Technology Data Exchange (ETDEWEB)

    Nanekar, Paritosh, E-mail: pnanekar@barc.gov.in [Quality Assurance Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Jothilakshmi, N. [Quality Assurance Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Jayakumar, T. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2013-12-15

    Highlights: • Phased array technique developed for weld joint inspection in BWR pressure vessel. • Simulation studies were carried out for conventional and phased array probe. • Conventional ultrasonic test shows in-adequate weld coverage and poor resolution. • Focused sound beam in phased array results in good resolution and sensitivity. • Ultrasonic phased array technique is validated on mock-up with reference defects. - Abstract: The weld joints in the reactor pressure vessel (RPV) of Boiling Water Reactors (BWR) are required to be examined periodically for assurance of structural integrity. Ultrasonic phased array examination technique has been developed in authors’ laboratory for inspection of the top flange to shell circumferential weld joint in RPV of BWRs, which are in operation in India since the late 1960s. The development involved detailed simulation studies for computation of focal laws followed by validation on mock-up. The paper brings out the limitations of the conventional ultrasonic technique and how this can be overcome by the phased array approach for the weld joint under consideration. The phased array technique was successfully employed for field examination of this weld joint in RPV during the re-fuelling outage.

  16. Dynamic circumferential ductile crack motion in finite length pipes with various end loadings

    International Nuclear Information System (INIS)

    Emery, A.F.; Kobayashi, A.S.; Love, W.J.; Perl, M.; Kistler, B.

    1981-01-01

    The computed time history, crack opening shape and tip velocity are presented for the ductile crack extension of circumferential cracks in finite length pipes. The pipes are loaded by: a) constant axial tension, b) constant axial displacement, c) constant end moment, and d) constant end rotation to study the effects of these significantly different types of loads. The crack extension is based upon a critical crack opening angle criterion. The results indicate that the extent of the crack movement and the extension velocity is primarily dependent upon the inertia of the moving pipe segments. With sufficient linear momentum, complete severance is obtained, while if the movement is more rotation than translation the cracks either do not extend or do so only slightly. Thus in tougher material, once it begins to extend, the crack may easily encircle the pipe while in more brittle materials it may not, since the moving segments of the pipe have not had time to develop sufficient momentum to force the continued extension of the crack into regions which are initially in compression. (orig.)

  17. A quantitative analysis of Tl-201 myocardial perfusion image with special reference to circumferential profile method

    International Nuclear Information System (INIS)

    Miyanaga, Hajime

    1982-01-01

    A quantitative analysis of thallium-201 myocardial perfusion image (MPI) was attempted by using circumferential profile method (CPM) and the first purpose of this study is to assess the clinical utility of this method for the detection of myocardial ischemia. In patients with coronary artery disease, CPM analysis to exercise T1-MPI showed high sensitivity (9/12, 75%) and specificity (9/9, 100%), whereas exercise ECG showed high sensitivity (9/12, 75%), but relatively low specificity (7/9, 78%). In patients with myocardial infarction, CPM also showed high sensitivity (34/38, 89%) for the detection of myocardial necrosis, compared with visual interpretation (31/38, 81%) and with ECG (31/38, 81%). Defect score was correlated well with the number of abnormal Q waves. In exercise study, CPM was also sensitive to the change of perfusion defect in T1-MPI produced by exercise. So the results indicate that CPM is a good method not only quantitatively but also objectively to analyze T1-MPI. Although ECG is the most commonly used diagnostic tool for ischemic heart disease, several exercise induced ischemic changes in ECG have been still on discussion as criteria. So the second purpose of this study is to evaluate these ischemic ECG changes by exercise T1-MPI analized quantitatively. ST depression (ischemic 1 mm and junctional 2 mm or more), ST elevation (1 mm or more), and coronary T wave reversion in exercise ECG were though to be ischemic changes. (J.P.N.)

  18. Circumferential tensile test method for mechanical property evaluation of SiC/SiC tube

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Ju-Hyeon, E-mail: 15096018@mmm.muroran-it.ac.jp [Graduate School, Muroran Institute of Technology, 27-1, Muroran, Hokkaido (Japan); Kishimoto, Hirotatsu [Graduate School, Muroran Institute of Technology, 27-1, Muroran, Hokkaido (Japan); OASIS, Muroran Institute of Technology, 27-1, Muroran, Hokkaido (Japan); Park, Joon-soo [OASIS, Muroran Institute of Technology, 27-1, Muroran, Hokkaido (Japan); Nakazato, Naofumi [Graduate School, Muroran Institute of Technology, 27-1, Muroran, Hokkaido (Japan); Kohyama, Akira [OASIS, Muroran Institute of Technology, 27-1, Muroran, Hokkaido (Japan)

    2016-11-01

    Highlights: • NITE SiC/SiC cooling channel system to be a candidate of divertor system in future. • Hoop strength is one of the important factors for a tube. • This research studies the relationship between deformation and strain of SiC/SiC tube. - Abstract: SiC fiber reinforced/SiC matrix (SiC/SiC) composite is expected to be a candidate material for the first-wall, components in the blanket and divertor of fusion reactors in future. In such components, SiC/SiC composites need to be formed to be various shapes. SiC/SiC tubes has been expected to be employed for blanket and divertor after DEMO reactor, but there is not established mechanical investigation technique. Recent progress of SiC/SiC processing techniques is likely to realize strong, having gas tightness SiC/SiC tubes which will contribute for the development of fusion reactors. This research studies the relationship between deformation and strain of SiC/SiC tube using a circumferential tensile test method to establish a mechanical property investigation method of SiC/SiC tubes.

  19. 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.

  20. 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.

  1. Circumferential tracheal resection with primary anastomosis for post-intubation tracheal stenosis: study of 24 cases.

    Science.gov (United States)

    Negm, Hesham; Mosleh, Mohamed; Fathy, Hesham

    2013-09-01

    The objective of this study is to evaluate the results of circumferential tracheal and cricotracheal resection with primary anastomosis for the treatment of post-intubation tracheal and cricotracheal stenosis. This is a retrospective analytical study. A total number of 24 patients were included in this study. The relevant preoperative, operative and postoperative records were collected and analyzed. Twenty patients were finally symptom-free reflecting an anastomosis success rate of 83.3 %. Variable grades of anastomotic restenosis occurred in 11 (45.8 %) patients, three patients were symptom-free and eight had airway obstructive symptoms. Four out of the eight patients with symptomatic restenosis were symptom-free with endoscopic dilatation while the remaining four patients required a permanent airway appliance (T-tube, tracheostomy) for the relief of airway obstruction and this group was considered as anastomotic failure. Cricoid involvement, associated cricoid resection and the type of anastomosis were the variables that had statistical impact on the occurrence of restenosis (P = 0.017, 0.017, 0.05; respectively). Tracheal resection with primary anastomosis is a safe effective treatment method for post-intubation tracheal stenosis in carefully selected patients. Restenosis does not always mean failure of the procedure since it may be successfully managed with endoscopic dilatation.

  2. Positioning means for circumferentially locating inspection apparatus in a nuclear reactor vessel

    International Nuclear Information System (INIS)

    Burns, D.C.

    1980-01-01

    There is provided for a reactor vessel inspection device a support ring sized to accommodate the circular path defined by three or more guide studs extending upwardly from the vessel. The support ring has at least three movably mounted guide stud bushings which can be positionally adjusted to align each bushing with one of the studs. When engaged, the guide studs and bushings yield a coarse positioning of the inspection device relative to the reactor vessel. Also provided are three support legs which are clamped to the support ring and dimensioned to an appropriate length. Two of the support legs have shoes clamped thereto, configured to rest on an internal circumferential flange within the reactor vessel. The third support leg is provided with a specially adapted shoe configured to engage a locating element, the exact position of which is known, within the vessel to achieve fine positioning of the inspection device relative to the reactor vessel. The support ring is additionally provided with an annular key which runs longitudinally about its outer periphery. Clamping means utilized to secure the guide stud bushings and the support legs to the support ring are provided with keyways to insure automatic self-alignment when fully tightened. (auth)

  3. Thermal fatigue crack growth on a thick wall tube containing a semi elliptical circumferential crack

    International Nuclear Information System (INIS)

    Deschanels, H.; Wakai, T.; Lacire, M.H.; Michel, B.

    2001-01-01

    In order to check the ability of the simplified assessment procedure (A16 guide) to predict fatigue crack growth, a benchmark problem was conducted. This work is carried out under the project ''agreement on the Exchange of Information and Collaboration in the field of Research and Development of Fast Breeder Reactor (FBR) between Europe (EU) and Japan''. Experimental work is conducted by PNC using Air cooled Thermal transient Test Facility (ATTF). Specimen is a thick wall tube containing a semi elliptical (3-D) circumferential crack and subjected to cyclic thermal transients. The constitutive material is the 304 austenitic stainless steel type SUS304. Due to thermal shock (650 C-300 C) the stress distribution through the wall is non-linear and well approximated using a 3 rd order polynomial. When comparing computations and tests data we observe a good agreement for the crack propagation in length. In crack depth, accurate results are obtained in the first part of the test, but on the later stage of the experiment the computations slightly underestimate the propagation (deep crack). In addition, we notice the importance of good evaluation of fracture mechanics parameters for non-linear stress distribution through the wall. At present A16 guide handbook gives stress intensity factor solutions for non-linear stress distribution through the wall. (author)

  4. Quantitative analysis of Tl-201 myocardial perfusion image with special reference to circumferential profile method

    Energy Technology Data Exchange (ETDEWEB)

    Miyanaga, Hajime [Kyoto Prefectural Univ. of Medicine (Japan)

    1982-08-01

    A quantitative analysis of thallium-201 myocardial perfusion image (MPI) was attempted by using circumferential profile method (CPM) and the first purpose of this study is to assess the clinical utility of this method for the detection of myocardial ischemia. In patients with coronary artery disease, CPM analysis to exercise T1-MPI showed high sensitivity (9/12, 75%) and specificity (9/9, 100%), whereas exercise ECG showed high sensitivity (9/12, 75%), but relatively low specificity (7/9, 78%). In patients with myocardial infarction, CPM also showed high sensitivity (34/38, 89%) for the detection of myocardial necrosis, compared with visual interpretation (31/38, 81%) and with ECG (31/38, 81%). Defect score was correlated well with the number of abnormal Q waves. In exercise study, CPM was also sensitive to the change of perfusion defect in T1-MPI produced by exercise. So the results indicate that CPM is a good method not only quantitatively but also objectively to analyze T1-MPI. Although ECG is the most commonly used diagnostic tool for ischemic heart disease, several exercise induced ischemic changes in ECG have been still on discussion as criteria. So the second purpose of this study is to evaluate these ischemic ECG changes by exercise T1-MPI analized quantitatively. ST depression (ischemic 1 mm and junctional 2 mm or more), ST elevation (1 mm or more), and coronary T wave reversion in exercise ECG were though to be ischemic changes.

  5. Estimations of creep behavior and failure life for a circumferentially notched specimen

    International Nuclear Information System (INIS)

    Kobayashi, Ken-ichi; Yokobori, Toshimitsu; Kikuchi, Kenji.

    1997-01-01

    No method with which to characterize and/or illustrate total creep behavior for specimens with notches, holes or cracks has been proposed. In this paper it is proposed that most creep curves can be drawn with a master curve for each creep test whenever test conditions and failure modes are similar to each other, and the lifetime ratio normalized by the rupture time is introduced. Using smooth and circumferentially notched specimens of 2.25 Cr-1 Mo steel, creep tests were performed at 600degC for examination of this concept. Furthermore, a θ projection method was used to describe creep curves for notched specimens and to extrapolate longer creep lives. Then, the whole creep curve shape for notched specimens could be easily drawn, except for that in the vicinity of the rupture point. However, longer creep lives of notched specimens were underestimated in comparison with a simple extrapolation of the experimental data. This resulted from the negative dependence of the parameter of θ 3 on the applied stress. (author)

  6. A study of the effect of circumferential temperature variations on fuel-sheath strain in an inert atmosphere

    International Nuclear Information System (INIS)

    Ferner, J.; Rondeau, R.K.; Rosinger, H.E.

    1983-07-01

    A failure model for Zircaloy-4 fuel sheaths has been developed and used to predict the effect of circumferential temperature variations (ΔT) on fuel-sheath strain behaviour in an inert atmosphere. In addition, experimental data were generated for fuel-sheath failures in the α and (α+β)-phase regions and compared to the predictions of the model. For both the experimental data and the model predictions it was found that increasing ΔT decreases sheath strain. Most of the reduction in burst strain with increasing ΔT occurs in the first 15 K to 20 K. For high ΔT values, burst strains in the α- and (α+β)-phase regions tend to an asymptotic value in the range 5 to 20 percent, irrespective of both heating rate and circumferential temperature variation. The BURST-2 computer code was used for these calculations

  7. Automated circumferential construction of first-order aqueous humor outflow pathways using spectral-domain optical coherence tomography.

    Science.gov (United States)

    Huang, Alex S; Belghith, Akram; Dastiridou, Anna; Chopra, Vikas; Zangwill, Linda M; Weinreb, Robert N

    2017-06-01

    The purpose was to create a three-dimensional (3-D) model of circumferential aqueous humor outflow (AHO) in a living human eye with an automated detection algorithm for Schlemm’s canal (SC) and first-order collector channels (CC) applied to spectral-domain optical coherence tomography (SD-OCT). Anterior segment SD-OCT scans from a subject were acquired circumferentially around the limbus. A Bayesian Ridge method was used to approximate the location of the SC on infrared confocal laser scanning ophthalmoscopic images with a cross multiplication tool developed to initiate SC/CC detection automated through a fuzzy hidden Markov Chain approach. Automatic segmentation of SC and initial CC’s was manually confirmed by two masked graders. Outflow pathways detected by the segmentation algorithm were reconstructed into a 3-D representation of AHO. Overall, only time and time with 1.4% false positive detection. 3-D representation of AHO pathways demonstrated variably thicker and thinner SC with some clear CC roots. Circumferential (360 deg), automated, and validated AHO detection of angle structures in the living human eye with reconstruction was possible.

  8. Circumferential resection margin (CRM) positivity after MRI assessment and adjuvant treatment in 189 patients undergoing rectal cancer resection.

    Science.gov (United States)

    Simpson, G S; Eardley, N; McNicol, F; Healey, P; Hughes, M; Rooney, P S

    2014-05-01

    The management of rectal cancer relies on accurate MRI staging. Multi-modal treatments can downstage rectal cancer prior to surgery and may have an effect on MRI accuracy. We aim to correlate the findings of MRI staging of rectal cancer with histological analysis, the effect of neoadjuvant therapy on this and the implications of circumferential resection margin (CRM) positivity following neoadjuvant therapy. An analysis of histological data and radiological staging of all cases of rectal cancer in a single centre between 2006 and 2011 were conducted. Two hundred forty-one patients had histologically proved rectal cancer during the study period. One hundred eighty-two patients underwent resection. Median age was 66.6 years, and male to female ratio was 13:5. R1 resection rate was 11.1%. MRI assessments of the circumferential resection margin in patients without neoadjuvant radiotherapy were 93.6 and 88.1% in patients who underwent neoadjuvant radiotherapy. Eighteen patients had predicted positive margins following chemoradiotherapy, of which 38.9% had an involved CRM on histological analysis. MRI assessment of the circumferential resection margin in rectal cancer is associated with high accuracy. Neoadjuvant chemoradiotherapy has a detrimental effect on this accuracy, although accuracy remains high. In the presence of persistently predicted positive margins, complete resection remains achievable but may necessitate a more radical approach to resection.

  9. Analysis on Propagation Characteristics and Experimental Verification of A1 Circumferential Waves in Nuclear Fuel Rods Coated with Oxide Layers

    International Nuclear Information System (INIS)

    Joo, Young Sang; Jung, Hyun Kyu; Cheong, Yong Moo; Ih, Jeong Guon

    1999-01-01

    The resonance scattering of acoustic waves from the cylindrical shells of nuclear fuel rods coated with oxide layers has been theoretically modeled and numerically analyzed for the propagation characteristics of the circumferential waves. The normal mode solutions of the scattering pressure of the coated shells have been obtained. The pure resonance components have been isolated using the newly proposed inherent background coefficients. The propagation characteristics of resonant circumferential waves for the shells coated with oxide layers are affected by the presence and the thickness of an oxide layer. The characteristics have been experimentally confirmed through the method of isolation and identification of resonances. The change of the phase velocity of the A 1 circumferential wave mode for the coated shell is negligible at the specified partial waves in spite of the presence of the oxide layer and the increase in coating thickness. Utilizing the invariability characteristics of the phase velocity of the A 1 mode, the oxide layer thickness of the coated shells can be estimated. A new nondestructive technique for the relative measurement of the coating thickness of coated shells has been proposed

  10. Development of new Z-factors for the evaluation of the circumferential surface crack in nuclear pipes

    International Nuclear Information System (INIS)

    Choi, Y.H.; Chung, Y.K.; Park, Y.W.; Lee, J.B.

    1997-01-01

    The purpose of this study is to develop new Z-factors to evaluate the behavior of a circumferential surface crack in nuclear pipe. Z-factor is a load multiplier used in the Z-factor method, which is one of the ASME Code Sec. XI's recommendations for the estimation of a surface crack in nuclear pipe. It has been reported that the load carrying capacities predicted from the current ASME Code Z-factors, are not well in agreement with the experimental results for nuclear pipes with a surface crack. In this study, new Z-factors for ferritic base metal, ferritic submerged arc welding (SAW) weld metal, austenitic base metal, and austenitic SAW weld metal are obtained by use of the surface crack for thin pipe (SC.TNP) method based on GE/EPRI method. The desirability of both the SC.TNP method and the new Z-factors is examined using the results from 48 pipe fracture experiments for nuclear pipes with a circumferential surface crack. The results show that the SC.TNP method is good for describing the circumferential surface crack behavior and the new Z-factors are well in agreement with the measured Z-factors for both ferritic and austenitic pipes. (orig.)

  11. Automated circumferential construction of first-order aqueous humor outflow pathways using spectral-domain optical coherence tomography

    Science.gov (United States)

    Huang, Alex S.; Belghith, Akram; Dastiridou, Anna; Chopra, Vikas; Zangwill, Linda M.; Weinreb, Robert N.

    2017-06-01

    The purpose was to create a three-dimensional (3-D) model of circumferential aqueous humor outflow (AHO) in a living human eye with an automated detection algorithm for Schlemm's canal (SC) and first-order collector channels (CC) applied to spectral-domain optical coherence tomography (SD-OCT). Anterior segment SD-OCT scans from a subject were acquired circumferentially around the limbus. A Bayesian Ridge method was used to approximate the location of the SC on infrared confocal laser scanning ophthalmoscopic images with a cross multiplication tool developed to initiate SC/CC detection automated through a fuzzy hidden Markov Chain approach. Automatic segmentation of SC and initial CC's was manually confirmed by two masked graders. Outflow pathways detected by the segmentation algorithm were reconstructed into a 3-D representation of AHO. Overall, only <1% of images (5114 total B-scans) were ungradable. Automatic segmentation algorithm performed well with SC detection 98.3% of the time and <0.1% false positive detection compared to expert grader consensus. CC was detected 84.2% of the time with 1.4% false positive detection. 3-D representation of AHO pathways demonstrated variably thicker and thinner SC with some clear CC roots. Circumferential (360 deg), automated, and validated AHO detection of angle structures in the living human eye with reconstruction was possible.

  12. Benchmarking circumferential resection margin (R1) resection rate for rectal cancer in the neoadjuvant era.

    Science.gov (United States)

    Chambers, W; Collins, G; Warren, B; Cunningham, C; Mortensen, N; Lindsey, I

    2010-09-01

    Circumferential resection margin (CRM) involvement (R1) is used to audit rectal cancer surgical quality. However, when downsizing chemoradiation (dCRT) is used, CRM audits both dCRT and surgery, its use reflecting a high casemix of locally advanced tumours. We aimed to evaluate predictors of R1 and benchmark R1 rates in the dCRT era, and to assess the influence of failure of steps in the multidisciplinary team (MDT) process to CRM involvement. A retrospective analysis of prospectively collected rectal cancer data was undertaken. Patients were classified according to CRM status. Uni- and multivariate analysis was undertaken of risk factors for R1 resection. The contribution of the steps of the MDT process to CRM involvement was assessed. Two hundred and ten rectal cancers were evaluated (68% T3 or T4 on preoperative staging). R1 (microscopic) and R2 (macroscopic) resections occurred in 20 (10%) and 6 patients (3%), respectively. Of several factors associated with R1 resections on univariate analysis, only total mesorectal excision (TME) specimen defects and threatened/involved CRM on preoperative imaging remained as independent predictors of R1 resections on multivariate analysis. Causes of R1 failure by MDT step classification found that less than half were associated with and only 15% solely attributable to a suboptimal TME specimen. Total mesorectal excision specimen defects and staging-predicted threatened or involved CRM are independent strong predictors of R1 resections. In most R1 resections, the TME specimen was intact. It is important to remember the contribution of both the local staging casemix and dCRT failure when using R1 rates to assess purely surgical competence.

  13. Gonioscopy-assisted Transluminal Trabeculotomy: An Ab Interno Circumferential Trabeculotomy: 24 Months Follow-up.

    Science.gov (United States)

    Grover, Davinder S; Smith, Oluwatosin; Fellman, Ronald L; Godfrey, David G; Gupta, Aditi; Montes de Oca, Ildamaris; Feuer, William J

    2018-05-01

    The purpose of this study was to provide 24-month follow-up on surgical success and safety of an ab interno circumferential 360-degree trabeculotomy. Chart review of patients who underwent a gonioscopy-assisted transluminal trabeculotomy (GATT) procedure was performed by 4 of the authors (D.S.G., O.S., R.L.F., and D.G.G.). The surgery was performed in adults with various types of open-angle glaucoma with preoperative intraocular pressures (IOPs) of ≥18 mm Hg. In total, 198 patients aged 24 to 89 years underwent the GATT procedure with at least 18 months follow-up. Patients with primary open-angle glaucoma had an average IOP decrease of 9.2 mm Hg at 24 months with an average decrease of 1.43 glaucoma medications. The mean percentage of IOP decrease in these primary open-angle glaucoma groups at 24 months was 37.3%. In secondary open-angle glaucoma, at 24 months there was an average decrease in IOP of 14.1 mm Hg on an average of 2.0 fewer medications. The mean percentage of IOP decrease in the secondary open-angle glaucoma groups at 24 months was 49.8%. The cumulative proportion of failure at 24 months ranged from 0.18 to 0.48, depending on the group. In all 6 study groups, at all 5 postoperative time points (3, 6, 12, 18, and 24 mo) the mean IOP and reduction in glaucoma medications was significantly reduced from baseline (P<0.001) with the exception of one time point. The 24-month results demonstrate that GATT is relatively safe and effective in treating various forms of open-angle glaucoma. The long-term results for GATT are relatively equivalent to those previously reported for GATT and ab externo trabeculotomy studies.

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

    Science.gov (United States)

    Gietelink, Lieke; Wouters, Michel W J M; Tanis, Pieter J; Deken, Marion M; Ten Berge, Martijn G; Tollenaar, Rob A E M; van Krieken, J Han; de Noo, Mirre E

    2015-09-01

    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 about CRM in the late 1990s, quality assurance on pathologic reporting was not available until the Dutch Surgical Colorectal Audit (DSCA) started in 2009. The present study describes the rates of CRM reporting and involvement since the start of the DSCA and analyzes whether improvement of these parameters can be attributed to the audit. Data from the DSCA (2009-2013) were analyzed. Reporting of CRM and CRM involvement was plotted for successive years, and variations of these parameters were analyzed in a funnelplot. Predictors of CRM involvement were determined in univariable analysis and the independent influence of year of registration on CRM involvement was analyzed in multivariable analysis. A total of 12,669 patients were included for analysis. The mean percentage of patients with a reported CRM increased from 52.7% to 94.2% (2009-2013) and interhospital variation decreased. The percentage of patients with CRM involvement decreased from 14.2% to 5.6%. In multivariable analysis, the year of DSCA registration remained a significant predictor of CRM involvement. After the introduction of the DSCA, a dramatic improvement in CRM reporting and a major decrease of CRM involvement after rectal cancer surgery have occurred. This study suggests that a national quality assurance program has been the driving force behind these achievements. Copyright © 2015 by the National Comprehensive Cancer Network.

  15. Effect of the circumferential resection margin on survival following rectal cancer surgery.

    Science.gov (United States)

    Kelly, S B; Mills, S J; Bradburn, D M; Ratcliffe, A A; Borowski, D W

    2011-04-01

    The aim was to determine the effect of the circumferential resection margin (CRM) on overall survival following surgical excision of rectal cancer. The effect of CRM on survival was examined by case mix-adjusted analysis of patients undergoing potentially curative excision of a rectal cancer between 1998 and 2002. Of 1896 patients, 1561 (82.3 per cent) had recorded data on the CRM. In 232 patients (14.9 per cent) tumour was found 1 mm or less from the CRM. In 370 patients (23.7 per cent) it was over 1 mm but no more than 5 mm from the CRM, and in 288 (18.4 per cent) it was over 5 mm but no more than 10 mm from the CRM. The remaining 671 patients (43.0 per cent) had a CRM exceeding 10 mm. Overall 5-year survival rates for these groups were 43.2, 51.7, 66.6 and 66.0 per cent respectively. Compared with patients with a CRM exceeding 10 mm, the adjusted risk of death was significantly increased for patients with a CRM of 1 mm or less (hazard ratio (HR) 1.61, P CRM (HR 1.02, P = 0.873). The adverse effect of a CRM greater than 1 mm but no larger than 5 mm was found particularly in mid-rectal cancers. A predicted CRM of 5 mm or less on preoperative staging should be considered for neoadjuvant treatment. Copyright © 2011 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd.

  16. What is the significance of the circumferential margin in locally advanced rectal cancer after neoadjuvant chemoradiotherapy?

    Science.gov (United States)

    Trakarnsanga, Atthaphorn; Gonen, Mithat; Shia, Jinru; Goodman, Karyn A; Nash, Garrett M; Temple, Larissa K; Guillem, José G; Paty, Philip B; Garcia-Aguilar, Julio; Weiser, Martin R

    2013-04-01

    The circumferential resection margin (CRM) is highly prognostic for local recurrence in rectal cancer surgery without neoadjuvant treatment. However, its significance in the setting of long-course neoadjuvant chemoradiotherapy (nCRT) is not well defined. Review of a single institution's prospectively maintained database from 1998 to 2007 identified 563 patients with locally advanced rectal cancer (T3/T4 and/or N1) receiving nCRT, followed after 6 weeks by total mesorectal excision (TME). Kaplan-Meier, Cox regression, and competing risk analysis were performed. The authors noted that 75 % of all patients had stage III disease as determined by endorectal ultrasound (ERUS) and/or magnetic resonance imaging (MRI). With median follow-up of 39 months after resection, local and distant relapse were noted in 12 (2.1 %) and 98 (17.4 %) patients, respectively. On competing risk analysis, the optimal cutoff point of CRM was 1 mm for local recurrence and 2 mm for distant metastasis. Factors independently associated with local recurrence included CRM ≤1 mm, and high-grade tumor (p = 0.012 and 0.007, respectively). CRM ≤2 mm, as well as pathological, nodal, and overall tumor stage are also significant independent risk factors for distant metastasis (p = 0.025, 0.010, and dataset of locally advanced rectal cancer treated with nCRT followed by TME, CRM ≤1 mm is an independent risk factor for local recurrence and is considered a positive margin. CRM ≤2 mm was associated with distant recurrence, independent of pathological tumor and nodal stage.

  17. Modeling of second-harmonic generation of circumferential guided wave propagation in a composite circular tube

    Science.gov (United States)

    Li, Mingliang; Deng, Mingxi; Gao, Guangjian; Xiang, Yanxun

    2018-05-01

    This paper investigated modeling of second-harmonic generation (SHG) of circumferential guided wave (CGW) propagation in a composite circular tube, and then analyzed the influences of interfacial properties on the SHG effect of primary CGW. Here the effect of SHG of primary CGW propagation is treated as a second-order perturbation to its linear wave response. Due to the convective nonlinearity and the inherent elastic nonlinearity of material, there are second-order bulk driving forces and surface/interface driving stresses in the interior and at the surface/interface of a composite circular tube, when a primary CGW mode propagates along its circumference. Based on the approach of modal expansion analysis for waveguide excitation, the said second-order driving forces/stresses are regarded as the excitation sources to generate a series of double-frequency CGW modes that constitute the second-harmonic field of the primary CGW propagation. It is found that the modal expansion coefficient of each double-frequency CGW mode is closely related to the interfacial stiffness constants that are used to describe the interfacial properties between the inner and outer circular parts of the composite tube. Furthermore, changes in the interfacial stiffness constants essentially influence the dispersion relation of CGW propagation. This will remarkably affect the efficiency of cumulative SHG of primary CGW propagation. Some finite element simulations have been implemented of response characteristics of cumulative SHG to the interfacial properties. Both the theoretical analyses and numerical simulations indicate that the effect of cumulative SHG is found to be much more sensitive to changes in the interfacial properties than primary CGW propagation. The potential of using the effect of cumulative SHG by primary CGW propagation to characterize a minor change in the interfacial properties is considered.

  18. Validation of the Predicted Circumferential and Radial Mode Sound Power Levels in the Inlet and Exhaust Ducts of a Fan Ingesting Distorted Inflow

    Science.gov (United States)

    Koch, L. Danielle

    2012-01-01

    Fan inflow distortion tone noise has been studied computationally and experimentally. Data from two experiments in the NASA Glenn Advanced Noise Control Fan rig have been used to validate acoustic predictions. The inflow to the fan was distorted by cylindrical rods inserted radially into the inlet duct one rotor chord length upstream of the fan. The rods were arranged in both symmetric and asymmetric circumferential patterns. In-duct and farfield sound pressure level measurements were recorded. It was discovered that for positive circumferential modes, measured circumferential mode sound power levels in the exhaust duct were greater than those in the inlet duct and for negative circumferential modes, measured total circumferential mode sound power levels in the exhaust were less than those in the inlet. Predicted trends in overall sound power level were proven to be useful in identifying circumferentially asymmetric distortion patterns that reduce overall inlet distortion tone noise, as compared to symmetric arrangements of rods. Detailed comparisons between the measured and predicted radial mode sound power in the inlet and exhaust duct indicate limitations of the theory.

  19. Effects of circumferential ankle pressure on ankle proprioception, stiffness, and postural stability: a preliminary investigation.

    Science.gov (United States)

    You, Sung H; Granata, Kevin P; Bunker, Linda K

    2004-08-01

    Cross-sectional repeated-measures design. Determine the effects of circumferential ankle pressure (CAP) intervention on proprioceptive acuity, ankle stiffness, and postural stability. The application of CAP using braces, taping, and adaptive shoes or military boots is widely used to address chronic ankle instability (CAI). An underlying assumption is that the CAP intervention might improve ankle stability through increased proprioceptive acuity and stiffness in the ankle. METHOD AND MEASURES: A convenience sample of 10 subjects was recruited from the local university community and categorized according to proprioceptive acuity (high, low) and ankle stability (normal, CAI). Proprioceptive acuity was measured when blindfolded subjects were asked to accurately reproduce a self-selected target ankle position before and after the application of CAP. Proprioceptive acuity was determined in 5 different ankle joint position sense tests: neutral, inversion, eversion, plantar flexion, and dorsiflexion. Joint position angles were recorded electromechanically using a potentiometer. Passive ankle stiffness was computed from the ratio of applied static moment versus angular displacement. Active ankle stiffness was determined from biomechanical analyses of ankle motion following a mediolateral perturbation. Postural stability was quantified from the center of pressure displacement in the mediolateral and the anteroposterior directions in unipedal stance. All measurements were recorded with and without CAP applied by a pediatric blood pressure cuff. Data were analyzed using a separate mixed-model analysis of variance (ANOVA) for each dependent variable. Post hoc comparison using Tukey's honestly significant difference (HSD) test was performed if significant interactions were obtained. Significance level was set at P<.05 for all analyses. Significant group (high versus low proprioceptive acuity) x CAP interactions were identified for postural stability. Passive ankle stiffness was

  20. Milligan-Morgan hemorrhoidectomy with anal cushion suspension and partial internal sphincter resection for circumferential mixed hemorrhoids

    Science.gov (United States)

    Lu, Ming; Shi, Guang-Ying; Wang, Guo-Qiang; Wu, Yan; Liu, Yang; Wen, Hao

    2013-01-01

    AIM: To identify a more effective treatment protocol for circumferential mixed hemorrhoids. METHODS: A total of 192 patients with circumferential mixed hemorrhoids were randomized into the treatment group, where they underwent Milligan-Morgan hemorrhoidectomy with anal cushion suspension and partial internal sphincter resection, or the control group, where traditional external dissection and internal ligation were performed. Postoperative recovery and complications were monitored. RESULTS: The time to wound healing was 12.96 ± 2.25 d in the treatment group shorter than 19.58 ± 2.71 d in the control group. Slight pain rate was 58.3% in the treatment group higher than 22.9% in the control group; moderate pain rate was 33.3% in the treatment group lower than 56.3% in the control group severe pain rate was 8.4% in the treatment group lower than 20.8% in the control group. No edema rate was 70.8% in the treatment group higher than 43.8% in the control group; mild local edema rate was 26% in the treatment group lower than 39.6% in the control group obvious local edema was 3.03% in the treatment group lower than 16.7% in the control group. No stenosis rate was 85.4% in the treatment group higher than 63.5% in the control group; moderate stenosis rate was 14.6% in the treatment group Lower than 27.1% in the control group severe anal stenosis rate was 0% in the treatment group lower than 9.4% in the control group. CONCLUSION: Milligan-Morgan hemorrhoidectomy with anal cushion suspension and partial internal sphincter resection is the optimal treatment for circumferential mixed hemorrhoids and can be widely applied in clinical settings. PMID:23946609

  1. Instrumented circumferential fusion for tuberculosis of the dorso-lumbar spine. A single or double stage procedure?

    Science.gov (United States)

    El-Sharkawi, Mohammad Mostafa; Said, Galal Zaki

    2012-02-01

    The purpose of this study was to present our experience in treating dorso-lumbar tuberculosis by one-stage posterior circumferential fusion and to compare this group with a historical group treated by anterior debridement followed by postero-lateral fusion and stabilization. Between 2003 and 2008, 32 patients with active spinal tuberculosis were treated by one-stage posterior circumferential fusion and prospectively followed for a minimum of two years. Pain severity was measured using Visual Analogue Scale (VAS). Neurological assessment was done using the Frankel scale. The operative data, clinical, radiological, and functional outcomes were also compared to a similar group of 25 patients treated with anterior debridement and fusion, followed 10-14 days later by posterior stabilization and postero-lateral fusion. The mean operative time and duration of hospital stay were significantly longer in the two-stage group. The mean estimated blood loss was also larger, though insignificantly, in the two-stage group. The incidence of complications was significantly lower in the one-stage group. At final follow-up, all 34 patients with pre-operative neurological deficits showed at least one Frankel grade of neurological improvement, all 57 patients showed significant improvement of their VAS back pain score, the mean kyphotic angle has significantly improved, all patients achieved solid fusion and 43 (75.4%) patients returned to their pre-disease activity level or work. Instrumented circumferential fusion, whether in one or two stages, is an effective treatment for dorso-lumbar tuberculosis. One-stage surgery, however, is advantageous because it has lower complication rate, shorter hospital stay, less operative time and blood loss.

  2. Value of the magnetic resonance imaging in the assessment of the circumferential resection margin (CRM) in patients with rectal cancer

    International Nuclear Information System (INIS)

    Seehaus, A.; Fatal Jaef, V.; Pietrani, M.; Ocantos, J.

    2009-01-01

    Purpose: To determine whether magnetic resonance imaging (MRI) can predict tumor involvement of the circumferential resection margin (CRM) in patients with rectal cancer. Materials and methods: Between april 2005 and march 2008, 70 consecutive patients (mean age 64, range 34-78 years), 40 F and 30 M, with endoscopy and biopsy- proven middle and lower rectal cancer. Non contrast enhanced MRI was performed on a Siemens Avanto 1.5 T. A phased array coil was used and T2 weighted thin section sequences (TR/TE 4200/88, slice thickness 3mm, gap 0, matrix 256 x 256, field of view 150 x 150 mm) were performed in axial, sagittal and coronal orientations. Patients received a 150 ml glycerin enema before examination. No air insufflations or intramuscular antispasmodic was used. The shortest distance from the tumor edge to the circumferential margin was measured. A distance ≤ ?2 mm, analyzed in axial slices, was considered as definition of circumferential margin involvement. Results: The CRM was 2 mm in both MRI and histopathological findings in 26 patients. In 8 cases the CRM was shorter on MRI than in histopathological sections. In 32 patients the CRM was respected in both exams and 4 patients were considered positive on histopathological findings but negative in MRI. The sensitivity, specificity, positive and negative predictive values for prediction of tumor involvement of CRM were 86%, 80%, 76% and 88%, respectively. Conclusions: MRI gives reliable information on tumor involvement of the CRM in patients with rectal cancer. This may provide accurate identification of an important prognostic risk factor in patients prior to surgical treatment. (authors) [es

  3. 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

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

    International Nuclear Information System (INIS)

    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

  5. Influence of operating conditions and atomizer design on circumferential liquid distribution from small pressure-swirl atomizer

    Directory of Open Access Journals (Sweden)

    Malý Milan

    2017-01-01

    Full Text Available The spray symmetry is an important aspect in most practical applications. However, it is often an overlooked parameter. A measurement of circumferential distribution was carried out by a circular-sectored vessel on several pressure-swirl atomizers with spill-line over a wide range of injection pressure. The obtained results show that the spray uniformity improves markedly with the injection pressure. The increase in a number of tangential entry ports has only a minor effect on the spray uniformity. Even a small mechanical corruption of the atomizer internal parts negatively affects the spray patternation.

  6. Influence of operating conditions and atomizer design on circumferential liquid distribution from small pressure-swirl atomizer

    Science.gov (United States)

    Malý, Milan; Janáčková, Lada; Jedelský, Jan; Jícha, Miroslav

    The spray symmetry is an important aspect in most practical applications. However, it is often an overlooked parameter. A measurement of circumferential distribution was carried out by a circular-sectored vessel on several pressure-swirl atomizers with spill-line over a wide range of injection pressure. The obtained results show that the spray uniformity improves markedly with the injection pressure. The increase in a number of tangential entry ports has only a minor effect on the spray uniformity. Even a small mechanical corruption of the atomizer internal parts negatively affects the spray patternation.

  7. Detection of leak-defective fuel rods using the circumferential Lamb waves excited by the resonance backscattering of ultrasonic pulses

    International Nuclear Information System (INIS)

    Choi, M.S.; Yang, M.S.; Kim, H.C.

    1992-01-01

    A new ultrasonic technique for detecting the infiltrated water in leaked fuel rods is developed. Propagation characteristics of the circumferential Lamb waves in the cladding tubes are estimated by the resonance scattering theory. The Lamb waves are excited by the resonance backscattering of ultrasonic pulses. In sound fuel rods, the existence of the Lamb waves is revealed by a series of periodic echoes. In leaked fuel rods, however, the Lamb waves are perturbed strongly by the scattered waves from the surface of fuel pellets, thus the periodic echoes are not observed. (author)

  8. 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.

  9. Instability predictions for circumferentially cracked Type-304 stainless steel pipes under dynamic loading. Volume 2. Appendixes. Final report. [BWR

    Energy Technology Data Exchange (ETDEWEB)

    Zahoor, A.; Wilkowski, G.; Abou-Sayed, I.; Marschall, C.; Broek, D.; Sampath, S.; Rhee, H.; Ahmad, J.

    1982-04-01

    This report provides methods to predict margins of safety for circumferentially cracked Type 304 stainless steel pipes subjected to applied bending loads. An integrated combination of experimentation and analysis research was pursued. Two types of experiments were performed: (1) laboratory-scale tests on center-cracked panels and bend specimens to establish the basic mechanical and fracture properties of Type 304 stainless steel, and (2) full-scale pipe fracture tests under quasi-static and dynamic loadings to assess the analysis procedures. Analyses were based upon the simple plastic collapse criterion, a J-estimation procedure, and elastic-plastic large-deformation finite element models.

  10. Instability predictions for circumferentially cracked Type-304 stainless steel pipes under dynamic loading. Volume 2. Appendixes. Final report

    International Nuclear Information System (INIS)

    Zahoor, A.; Wilkowski, G.; Abou-Sayed, I.; Marschall, C.; Broek, D.; Sampath, S.; Rhee, H.; Ahmad, J.

    1982-04-01

    This report provides methods to predict margins of safety for circumferentially cracked Type 304 stainless steel pipes subjected to applied bending loads. An integrated combination of experimentation and analysis research was pursued. Two types of experiments were performed: (1) laboratory-scale tests on center-cracked panels and bend specimens to establish the basic mechanical and fracture properties of Type 304 stainless steel, and (2) full-scale pipe fracture tests under quasi-static and dynamic loadings to assess the analysis procedures. Analyses were based upon the simple plastic collapse criterion, a J-estimation procedure, and elastic-plastic large-deformation finite element models

  11. Instability predictions for circumferentially cracked Type-304 stainless-steel pipes under dynamic loading. Final report. [BWR

    Energy Technology Data Exchange (ETDEWEB)

    Zahoor, A.; Wilkowski, G.; Abou-Sayed, I.; Marschall, C.; Broek, D.; Sampath, S.; Rhee, H.; Ahmad, J.

    1982-04-01

    This report provides methods to predict margins of safety for circumferentially cracked Type 304 stainless steel pipes subjected to applied bending loads. An integrated combination of experimentation and analysis research was pursued. Two types of experiments were performed: (1) laboratory-scale tests on center-cracked panels and bend specimens to establish the basic mechanical and fracture properties of Type 304 stainless steel, and (2) full-scale pipe fracture tests under quasi-static and dynamic loadings to assess the analysis procedures. Analyses were based upon the simple plastic collapse criterion, a J-estimation procedure, and elastic-plastic large-deformation finite element models.

  12. Recent investigations and tests with the BBR winding system for circumferential prestressing of concrete vessels and containments

    International Nuclear Information System (INIS)

    Schuett, K.; Speck, F.E.

    1993-01-01

    Prestressed concrete pressure vessels for nuclear power stations need post-tensioning systems of large capacity. For the circumferential prestressing, the continuous winding of prestressing steel has several advantages when compared to the use of large numbers of single tendons. About 15 years ago Bureau BBR Ltd (Zuerich) developed the winding system SW 8500. The further development work interrupted at that time for lack of immediate applications was resumed 4 years ago by Bureau BBR together with SUSPA on the ground of new projects being evaluated

  13. 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

  14. Refinement and evaluation of crack-opening-area analyses for circumferential through-wall cracks in pipes

    International Nuclear Information System (INIS)

    Rahman, S.; Brust, F.; Ghadiali, N.; Krishnaswamy, P.; Wilkowski, G.; Choi, Y.H.; Moberg, F.; Brickstad, B.

    1995-04-01

    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 impingement 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. These leak rates depend on the crack-opening area of a 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 11. This study was requested by the NRC to review, evaluate, and refine current analytical models for crack-opening-area analyses of pipes with circumferential through-wall cracks. Twenty-five pipe experiments were analyzed to determine the accuracy of the predictive models. Several practical aspects of crack-opening such as; crack-face pressure, off-center cracks, restraint of pressure-induced bending, cracks in thickness transition regions, weld residual stresses, crack-morphology models, and thermal-hydraulic analysis, were also investigated. 140 refs., 105 figs., 41 tabs

  15. Cylindrical magnetization model for glass-coated microwires with circumferential anisotropy: Comparison with experiments and skin effect

    Energy Technology Data Exchange (ETDEWEB)

    Torrejon, J., E-mail: torrejondiaz.jacob@nims.go.jp [Laboratoire de Physique des Solides, Univ. Paris-Sud, CNRS UMR 8502, 91405 Orsay (France); Instituto de Ciencia de Materiales, CSIC, 28049 Madrid (Spain); Thiaville, A. [Laboratoire de Physique des Solides, Univ. Paris-Sud, CNRS UMR 8502, 91405 Orsay (France); Adenot-Engelvin, A.-L. [CEA, DAM, Le Ripault, 37260 Monts (France); Vazquez, M. [Instituto de Ciencia de Materiales, CSIC, 28049 Madrid (Spain)

    2014-05-01

    The present manuscript represents the third part of a series of studies about a continuous micromagnetic model for amorphous microwires with non-uniform magnetic structure (Torrejon et al., J. Magn. Magn. Mater. 323 (2011) 283; Torrejon et al., J. Magn. Magn. Mater. 333 (2013) 144). Here we compare the predictions of this model with experiments, and show the validity of this approach when a uniform magnetic structure in the microwire cannot be considered. The analyzed microwires exhibit ultrasoft magnetic behaviour and negative magnetostriction, with a non-uniform magnetic structure composed of an axially magnetized inner core exchange-coupled with a circumferentially magnetized outer shell. The static properties were obtained by magnetometry. The high frequency response, axial permeability, was measured from a conventional single coil permeameter connected to a network analyzer. The microwave response is strongly affected by skin effect, which therefore needs to be taken into account for comparison with theory. The validity of the continuous model is proved through the experimental dependence of the permeability on axial static field. Finally, the efficient dynamic magnetization is evaluated from the imaginary component of permeability. - Highlights: • We model magnetic properties of microwires with circumferential anisotropy. • Skin effect correction has to be considered for small microwires. • Validity of model is proved by permeability dependence on axial static field. • Wires with small volume of the core can be well described by macrospin approach. • The exchange-coupled continuous core-shell model is compared to experiments.

  16. An approximative solution for limit load of piping branch junctions with circumferential crack and finite element validation

    International Nuclear Information System (INIS)

    Xuan Fuzhen; Liu Changjun; Li Peining

    2005-01-01

    This paper is concerned with the prediction of limit load of the piping branch junctions with circumferential crack under internal pressure. Recently, we have developed a new approach for predicting the limit load of two-cylinder intersection structures with diameter ratio larger than 0.5, which has been successfully applied to defect free cases under various loading conditions. In the present work, we consider the extension of the approach to cover cracked piping branch junctions. On the basis of stress analysis in the vicinity of intersection line, a closed form of limit load solution for piping branch junctions with circumferential crack was developed. Then, 36 finite element (FE) models of piping branch junction with various dimensions of structure and crack were analyzed by using nonlinear finite element software. The limit loads from FE analysis and the proposed solution are compared with each other. Overall good agreement between the estimated solutions and the FE results provides confidence in the use of the proposed formulae for defect assessment of piping branch junctions in practice

  17. The Aerodynamic Performance of an Over-the-Rotor Liner With Circumferential Grooves on a High Bypass Ratio Turbofan Rotor

    Science.gov (United States)

    Bozak, Richard F.; Hughes, Christopher E.; Buckley, James

    2013-01-01

    While liners have been utilized throughout turbofan ducts to attenuate fan noise, additional attenuation is obtainable by placing an acoustic liner over-the-rotor. Previous experiments have shown significant fan performance losses when acoustic liners are installed over-the-rotor. The fan blades induce an oscillating flow in the acoustic liners which results in a performance loss near the blade tip. An over-the-rotor liner was designed with circumferential grooves between the fan blade tips and the acoustic liner to reduce the oscillating flow in the acoustic liner. An experiment was conducted in the W-8 Single-Stage Axial Compressor Facility at NASA Glenn Research Center on a 1.5 pressure ratio fan to evaluate the impact of this over-the-rotor treatment design on fan aerodynamic performance. The addition of a circumferentially grooved over-the-rotor design between the fan blades and the acoustic liner reduced the performance loss, in terms of fan adiabatic efficiency, to less than 1 percent which is within the repeatability of this experiment.

  18. Calculation of stress intensity factors for circumferential semi-elliptical cracks with high aspect ratio in pipes

    International Nuclear Information System (INIS)

    Zareei, A.; Nabavi, S.M.

    2016-01-01

    In this paper, stress intensity factors are calculated at the deepest point of an internal circumferential semi-elliptical crack in a pipe subjected to any arbitrary load. Based on the three dimensional finite element analysis, a weight function is proposed for high aspect ratio semi-elliptical cracks in pipes. An effective expression is developed analytically to evaluate the stress intensity factor using the weight function method. For several crack face stress fields and welding residual stress distributions, the weight function is validated against finite element data and those in the literature. Based on the comparison results, it can be concluded that the solution proposed in this paper is effective in engineering applications. - Highlights: • Analysis of internal circumferential semi-elliptical cracks with high aspect ratio in pipes. • A weight function is proposed for the calculation of the stress intensity factors for the deepest point of the crack. • An effective closed form expression is proposed to evaluate the stress intensity factors. • Prediction of stress intensity factors for any applied stress gradients through the wall thickness without any limitations. • A three-dimensional finite element modeling employs to calculate the stress intensity factors for different geometries.

  19. Statistical and Graphical Assessment of Circumferential and Radial Hardness Variation of AISI 4140, AISI 1020 and AA 6082 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Hamad Al-Khalid

    2011-12-01

    Full Text Available Hardness homogeneity of the commonly used structural ferrous and nonferrous engineering materials is of vital importance in the design stage, therefore, reliable information regarding material properties homogeneity should be validated and any deviation should be addressed. In the current study the hardness variation, over wide spectrum radial locations of some ferrous and nonferrous structural engineering materials, was investigated. Measurements were performed over both faces (cross-section of each stock bar according to a pre-specified stratified design, ensuring the coverage of the entire area both in radial and circumferential directions. Additionally the credibility of the apparatus and measuring procedures were examined through a statistically based calibration process of the hardness reference block. Statistical and response surface graphical analysis are used to examine the nature, adequacy and significance of the measured hardness values. Calibration of the apparatus reference block proved the reliability of the measuring system, where no strong evidence was found against the stochastic nature of hardness measures over the various stratified locations. Also, outlier elimination procedures were proved to be beneficial only at fewer measured points. Hardness measurements showed a dispersion domain that is within the acceptable confidence interval. For AISI 4140 and AISI 1020 steels, hardness is found to have a slight decrease trend as the diameter is reduced, while an opposite behavior is observed for AA 6082 aluminum alloy. However, no definite significant behavior was noticed regarding the effect of the sector sequence (circumferential direction.

  20. Development of K and COD Solutions of Non-idealized Circumferential Through-wall Cracks for PARTRIDGE

    International Nuclear Information System (INIS)

    Park, Jeong Soon; Kim, Sun Hye; Kim, Jin Su and others

    2013-01-01

    PARTRIDGE (Probabilistic Analysis as a Regulatory Tool for Risk Informed Decision GuidancE) is an international research program, main purposes of which are to enhance PRO-LOCA (PRObabilistic-Loss Of Coolant Accident) code, a research piping probabilistic fracture mechanics code originally developed for USNRC, and to support the development of a new modular probabilistic fracture mechanics code, xLPR(Extremely Low Probability of Rupture). KINS, KHNP, and KEPCO E and C established a Korea Consortium to take part in the PARTRIDGE and have provided not only financial but also technical contribution to it. As part of the research in-kind contribution, Korea Consortium has developed new Mode I stress intensity factors (KI) and crack opening displacements (COD, δ) for non-idealized through-wall cracks along with EMC2 (Engineering Mechanics Corporation of Columbus). In this paper, the results of linear elastic fracture mechanics (LEFM) analysis for non-idealized circumferential through-wall cracks performed by Korea Consortium were provided. Korea Consortium, KINS, KHNP, and KEPCO E and C, performs LEFM analyses for non-idealized circumferential through-wall cracks as part of in-kind contribution to the international research program called PARTRIDGE

  1. Plastic fracture mechanics prediction of fracture instability in a circumferentially cracked pipe in bending - 1. J-integral analysis

    Energy Technology Data Exchange (ETDEWEB)

    Zahoor, A.; Kanninen, M.F.

    1981-11-01

    A method of evaluating the J-integral for a circumferentially cracked pipe in bending is proposed. The method allows a J-resistance curve to be evaluated directly from the load-displacement record obtained in a pipe fracture experiment. It permits an analysis for fracture instability in a circumferential crack growth using a J-resistance curve and the tearing modulus parameter. The influence of the system compliance on fracture instability is discussed in conjunction with the latter application. The importance of using a J-resistance curve that is consistent with the type of constraint for a given application is emphasized. The possibility of a pipe fracture emanating from a stress corrosion crack in the heat-affected zones of girth-welds in Type 304 stainless steel pipes was investigated. The J-resistance curve was employed. A pipe fracture experiment was performed using a spring-loaded four-point bending system that simulated an 8.8-m long section of unsupported 102-mm-dia pipe. An initial through-wall crack of length equal to 104 mm was used. Fracture instability was predicted to occur between 15.2 and 22.1 mm of stable crack growth at each tip. In the actual experiment, the onset of fracture instability occurred beyond maximum load at an average stable crack growth of 11.7 to 19 mm at each tip. 24 refs.

  2. Plastic fracture mechanics prediction of fracture instability in a circumferentially cracked pipe in bending - 1. J-integral analysis

    International Nuclear Information System (INIS)

    Zahoor, A.; Kanninen, M.F.

    1981-01-01

    A method of evaluating the J-integral for a circumferentially cracked pipe in bending is proposed. The method allows a J-resistance curve to be evaluated directly from the load-displacement record obtained in a pipe fracture experiment. It permits an analysis for fracture instability in a circumferential crack growth using a J-resistance curve and the tearing modulus parameter. The influence of the system compliance on fracture instability is discussed in conjunction with the latter application. The importance of using a J-resistance curve that is consistent with the type of constraint for a given application is emphasized. The possibility of a pipe fracture emanating from a stress corrosion crack in the heat-affected zones of girth-welds in Type 304 stainless steel pipes was investigated. The J-resistance curve was employed. A pipe fracture experiment was performed using a spring-loaded four-point bending system that simulated an 8.8-m long section of unsupported 102-mm-dia pipe. An initial through-wall crack of length equal to 104 mm was used. Fracture instability was predicted to occur between 15.2 and 22.1 mm of stable crack growth at each tip. In the actual experiment, the onset of fracture instability occurred beyond maximum load at an average stable crack growth of 11.7 to 19 mm at each tip. 24 refs

  3. An appraisal of procedures used to give the criterion for instability of a through-wall circumferential crack in a stainless steel piping system

    International Nuclear Information System (INIS)

    Smith, E.

    1989-01-01

    Against the background of the problem of intergranular stress corrosion cracking of 304 stainless steel in Boiling Water Reactor piping systems, this paper presents a critical appraisal of procedures that are currently used to give the criterion for instability of a through-wall circumferential crack in a stainless steel piping system. Particular attention is focussed on a simple procedure developed by Cotter, Chang and Zahoor, which has been applied to specific piping systems, the objective being to underpin its viability. The considerations are applicable to not only Boiling Water Reactor piping systems, but to other piping systems where pipe failure due to circumferential cracking is a potential problem. (author)

  4. Application of a nonlinear spring element to analysis of circumferentially cracked pipe under dynamic loading

    International Nuclear Information System (INIS)

    Olson, R.; Scott, P.; Wilkowski, G.M.

    1992-01-01

    As part of the US NRC's Degraded Piping Program, the concept of using a nonlinear spring element to simulate the response of cracked pipe in dynamic finite element pipe evaluations was initially proposed. The nonlinear spring element is used to represent the moment versus rotation response of the cracked pipe section. The moment-rotation relationship for the crack size and material of interest is determined from either J-estimation scheme analyses or experimental data. In this paper, a number of possible approaches for modeling the nonlinear stiffness of the cracked pipe section are introduced. One approach, modeling the cracked section moment rotation response with a series of spring-slider elements, is discussed in detail. As part of this discussion, results from a series of finite element predictions using the spring-slider nonlinear spring element are compared with the results from a series of dynamic cracked pipe system experiments from the International Piping Integrity Research Group (IPIRG) program

  5. Plastic Limit Loads for Slanted Circumferential Through-Wall Cracked Pipes Using 3D Finite-Element Limit Analyses

    International Nuclear Information System (INIS)

    Jang, Hyun Min; Cho, Doo Ho; Kim, Young Jin; Huh, Nam Su; Shim, Do Jun; Choi, Young Hwan; Park, Jung Soon

    2011-01-01

    On the basis of detailed 3D finite-element (FE) limit analyses, the plastic limit load solutions for pipes with slanted circumferential through-wall cracks (TWCs) subjected to axial tension, global bending, and internal pressure are reported. The FE model and analysis procedure employed in the present numerical study were validated by comparing the present FE results with existing solutions for plastic limit loads of pipes with idealized TWCs. For the quantification of the effect of slanted crack on plastic limit load, slant correction factors for calculating the plastic limit loads of pipes with slanted TWCs from pipes with idealized TWCs are newly proposed from extensive 3D FE calculations. These slant-correction factors are presented in tabulated form for practical ranges of geometry and for each set of loading conditions

  6. A rotordynamic analysis of circumferentially-grooved pump seals based on a three-control-volume theory

    International Nuclear Information System (INIS)

    Ha, Tae Woong; Lee, An Sung

    2000-01-01

    In this paper the leakage prediction and rotordynamic analysis of an annular seal with a smooth rotor and circumferentially grooved stator are performed based on a three-control-volume theory. The present analysis is validated by comparing with the experimental data of Iwatsubo and Sheng and theoretical results suggested by Marquette and Childs. For the leakage prediction the present analysis shows a good agreement with Marquette and Childs' result and a qualitation agreement with Iwatsubo and Shengs' experimental data. Direct and cross-coupled stiffness coefficients show closer agreement with the experimental values than those of Marquette and Childs. However, direct damping coefficient shows greater discrepancy from the experimental value than Marquette and Childs'

  7. Investigations of leak opening and outflow behaviour on straight pipes with circumferential cracks with internal pressure and bending load

    International Nuclear Information System (INIS)

    Grebner, H.; Hoefler, A.; Hunger, H.

    1989-01-01

    The experiments carried out so far on straight pipes with circumferential cracks and results of subsequent calculations from this experiment are introduced. The subsequent calculations are not yet completed at all points. From the experiments one can record that the selected crack sizes and stresses have guaranteed stable crack behaviour in all cases. The comparison of experimental and calculated crack openings shows satisfactory agreement (difference about 20% for experiment E22.03. The compared leak rates show differences of up to about 50% (in isolated cases even more). For small leak rates (0.01 to 0.1 kg/sec), one can expect a difference of about 100% between calculation and experiment. For medium leak rates, we regard a maximum difference of about 30% as achievable. For large leak rates, the achievable accuracy plays no part for the detectability. (orig./DG) [de

  8. Crack tip field in circumferentially-cracked round bar (CCRB in tension affected by loss of axial symmetry

    Directory of Open Access Journals (Sweden)

    J. Toribio

    2017-07-01

    Full Text Available In this paper, the stress intensity factor (SIF is computed in a circumferentially-cracked round bar (CCRB subjected to tensile loading, considering that the resistant ligament is circular and exhibits certain eccentricity in relation to the cylinder axis. The computation was performed by means of the finite element method (FEM using a three dimensional (3D model and the J-integral, the analyzed variable being the eccentricity of the circular ligament. Results show that the SIF is higher at the deepest point of the crack and that an increase of eccentricity (in relation to the bar axis raises the difference between the SIF values along the crack front. From a certain value of the misalignment a bending effect appears, so that the crack remains closed in the area near the point of lower depth.

  9. Computerized Cuff Pressure Algometry as Guidance for Circumferential Tissue Compression for Wearable Soft Robotic Applications: A Systematic Review.

    Science.gov (United States)

    Kermavnar, Tjaša; Power, Valerie; de Eyto, Adam; O'Sullivan, Leonard W

    2018-02-01

    In this article, we review the literature on quantitative sensory testing of deep somatic pain by means of computerized cuff pressure algometry (CPA) in search of pressure-related safety guidelines for wearable soft exoskeleton and robotics design. Most pressure-related safety thresholds to date are based on interface pressures and skin perfusion, although clinical research suggests the deep somatic tissues to be the most sensitive to excessive loading. With CPA, pain is induced in deeper layers of soft tissue at the limbs. The results indicate that circumferential compression leads to discomfort at ∼16-34 kPa, becomes painful at ∼20-27 kPa, and can become unbearable even below 40 kPa.

  10. Structural integrity of whipping pipes following a postulated circumferential break - a contribution to determining strain levels acceptable under faulted conditions

    International Nuclear Information System (INIS)

    Charalambus, B.; Labes, M.

    1993-01-01

    It is postulated that a break of a thin-walled pipe does not cause a subsequent break in the pipe in the vicinity of a plastic hinge even when the wall is weakened by a 60 circumferential crack of a depth of 30% of the wall thickness on the tension side. This pipe behavior is the result of plastic buckling in the compression side and applies to pipes of diameter-to-thickness ratio larger than 20. For this type of pipe, the axial strains decrease with increasing diameter-to-thickness ratio in the tension side. As the pipe is only loaded in one direction, there is no cyclic behavior that can trigger a subsequent break. (orig.)

  11. The stability of growth of a through-wall circumferential crack in a cylindrical pipe subjected to bending deformation

    International Nuclear Information System (INIS)

    Smith, E.

    1987-01-01

    Tada, Paris and Gamble have used the tearing modulus approach to examine the stability of growth of a through-wall circumferential crack in a 304 stainless steel circular cylindrical pipe subject to bending deformation. They showed that crack growth is stable, in the sense that growth requires the rotation imposed at the pipe-ends to be increased, provided the pipe length is less than a critical length Lsub(c), which is given by their analysis. The Tada-Paris-Gamble analysis focuses on the question of the stability, or otherwise, of crack growth at the onset of crack extension. The analysis does not consider the possibilities that (a) instability might occur after some stable crack growth, and (b) arrest might occur after some unstable growth. A study of these aspects of the circumferential crack growth problem using the tearing modulus approach is precluded by the geometry dependence of the J-crack growth resistance curve. Consequently the present paper uses a crack tip opening angle criterion to describe crack growth, and thereby demonstrates that possibilities (a) and (b) should both occur, depending on the initial crack length and pipe length. In terms of relevance to the technologically important problem of cracking in Boiling Water Reactor piping, the important conclusion stemming from the paper's analysis is that stability of crack growth after the onset of crack extension is assured if the pipe length is less than a critical length L'sub(c). L'sub(c) is less than Lsub(c), the critical length relevant to the onset of crack extension, but it is still appreciably greater than the pipe run lengths in actual reactor piping systems, and safety against guillotine failure of a pipe is therefore generally assured. (author)

  12. The Influence of Hospital Volume on Circumferential Resection Margin Involvement: Results of the Dutch Surgical Colorectal Audit.

    Science.gov (United States)

    Gietelink, Lieke; Henneman, Daniel; van Leersum, Nicoline J; de Noo, Mirre; Manusama, Eric; Tanis, Pieter J; Tollenaar, Rob A E M; Wouters, Michel W J M

    2016-04-01

    This population-based study evaluates the association between hospital volume and CRM (circumferential resection margin) involvement, adjusted for other confounders, in rectal cancer surgery. A low hospital volume (risk of CRM involvement (odds ratio=1.54; 95% CI: 1.12-2.11). To evaluate the association between hospital volume and CRM (circumferential resection margin) involvement in rectal cancer surgery. To guarantee the quality of surgical treatment of rectal cancer, the Association of Surgeons of the Netherlands has stated a minimal annual volume standard of 20 procedures per hospital. The influence of hospital volume has been examined for different outcome variables in rectal cancer surgery. Its influence on the pathological outcome (CRM) however remains unclear. As long-term outcomes are best predicted by the CRM status, this parameter is of essential importance in the debate on the justification of minimal volume standards in rectal cancer surgery. Data from the Dutch Surgical Colorectal Audit (2011-2012) were used. Hospital volume was divided into 3 groups, and baseline characteristics were described. The influence of hospital volume on CRM involvement was analyzed, in a multivariate model, between low- and high-volume hospitals, according to the minimal volume standards. This study included 5161 patients. CRM was recorded in 86% of patients. CRM involvement was 11% in low-volume group versus 7.7% and 7.9% in the medium- and high-volume group (P≤0.001). After adjustment for relevant confounders, the influence of hospital volume on CRM involvement was still significant odds ratio (OR) = 1.54; 95% CI: 1.12-2.11). The outcomes of this pooled analysis support minimal volume standards in rectal cancer surgery. Low hospital volume was independently associated with a higher risk of CRM involvement (OR = 1.54; 95% CI: 1.12-2.11).

  13. Circumferential targeted renal sympathetic nerve denervation with preservation of the renal arterial wall using intra-luminal ultrasound

    Science.gov (United States)

    Roth, Austin; Coleman, Leslie; Sakakura, Kenichi; Ladich, Elena; Virmani, Renu

    2015-03-01

    An intra-luminal ultrasound catheter system (ReCor Medical's Paradise System) has been developed to provide circumferential denervation of the renal sympathetic nerves, while preserving the renal arterial intimal and medial layers, in order to treat hypertension. The Paradise System features a cylindrical non-focused ultrasound transducer centered within a balloon that circulates cooling fluid and that outputs a uniform circumferential energy pattern designed to ablate tissues located 1-6 mm from the arterial wall and protect tissues within 1 mm. RF power and cooling flow rate are controlled by the Paradise Generator which can energize transducers in the 8.5-9.5 MHz frequency range. Computer simulations and tissue-mimicking phantom models were used to develop the proper power, cooling flow rate and sonication duration settings to provide consistent tissue ablation for renal arteries ranging from 5-8 mm in diameter. The modulation of these three parameters allows for control over the near-field (border of lesion closest to arterial wall) and far-field (border of lesion farthest from arterial wall, consisting of the adventitial and peri-adventitial spaces) depths of the tissue lesion formed by the absorption of ultrasonic energy and conduction of heat. Porcine studies have confirmed the safety (protected intimal and medial layers) and effectiveness (ablation of 1-6 mm region) of the system and provided near-field and far-field depth data to correlate with bench and computer simulation models. The safety and effectiveness of the Paradise System, developed through computer model, bench and in vivo studies, has been demonstrated in human clinical studies.

  14. PWR clad ballooning: The effect of circumferential clad temperature variations on the burst strain/burst temperature relationship

    International Nuclear Information System (INIS)

    Barlow, P.

    1983-01-01

    By experiment, it has been shown by other workers that there is a reduction in the creep ductility of Zircaloy 4 in the α+β phase transition region. Results from single rod burst tests also show a reduction in burst strain in the α+β phase region. In this report it is shown theoretically that for single rod burst tests in the presence of circumferential temperature gradients, the temperature dependence of the mean burst strain is not determined by temperature variations in creep ductility, but is governed by the temperature sensitivity of the creep strain rate, which is shown to be a maximum in the α+β phase transition region. To demonstrate this effect, the mean clad strain at burst was calculated for creep straining at different temperature levels in the α, α+β and β phase regions. Cross-pin temperature gradients were applied which produced strain variations around the clad which were greatest in the α+β phase region. The mean strain at burst was determined using a maximum local burst strain (i.e. a creep ductility) which is independent of temperature. By assuming cross-pin temperature gradients which are typical of those observed during burst tests, then the calculated mean burst strain/burst temperature relationship gave good agreement with experiment. The calculations also show that when circumferential temperature differences are present, the calculated mean strain at burst is not sensitive to variations in the magnitude of the assumed creep ductility. This reduces the importance of the assumed burst criterion in the calculations. Hence a temperature independent creep ductility (e.g. 100% local strain) is adequate as a burst criterion for calculations under PWR LOCA conditions. (author)

  15. Posterior transpedicular approach with circumferential debridement and anterior reconstruction as a salvage procedure for symptomatic failed vertebroplasty.

    Science.gov (United States)

    Chiu, Yen-Chun; Yang, Shih-Chieh; Chen, Hung-Shu; Kao, Yu-Hsien; Tu, Yuan-Kun

    2015-02-10

    Complications and failure of vertebroplasty, such as cement dislodgement, cement leakage, or spinal infection, usually result in spinal instability and neural element compression. Combined anterior and posterior approaches are the most common salvage procedure for symptomatic failed vertebroplasty. The purpose of this study is to evaluate the feasibility and efficacy of a single posterior approach technique for the treatment of patients with symptomatic failed vertebroplasty. Ten patients with symptomatic failed vertebroplasty underwent circumferential debridement and anterior reconstruction surgery through a single-stage posterior transpedicular approach (PTA) from January 2009 to December 2011 at our institution. The differences of visual analog scale (VAS), neurologic status, and vertebral body reconstruction before and after surgery were recorded. The clinical outcomes of patients were categorized as excellent, good, fair, or poor based on modified Brodsky's criteria. The symptomatic failed vertebroplasty occurred between the T11 and L3 vertebrae with one- or two-level involvement. The average VAS score was 8.3 (range, 7 to 9) before surgery, significantly decreased to 3.2 (range, 2 to 4) after surgery (p surgery was 17.3° (range, 4° to 35°) (p surgery was 1 mm (range, 0 to 2). The neurologic status of Frankel's scale significantly improved after surgery (p = 0.014) and at 1 year after surgery (p = 0.046). No one experienced severe complications such as deep wound infection or neurologic deterioration. All patients achieved good or excellent outcomes after surgery based on modified Brodsky's criteria (p surgery with circumferential debridement and anterior reconstruction technique provides good clinical outcomes and low complication rate, which can be considered as an alternative method to combined anterior and posterior approaches for patients with symptomatic failed vertebroplasty.

  16. Stepwise circumferential and focal ablation of Barrett's esophagus with high-grade dysplasia: results of the first prospective series of 11 patients

    NARCIS (Netherlands)

    Gondrie, J. J.; Pouw, R. E.; Sondermeijer, C. M. T.; Peters, F. P.; Curvers, W. L.; Rosmolen, W. D.; Krishnadath, K. K.; ten Kate, F.; Fockens, P.; Bergman, J. J.

    2008-01-01

    BACKGROUND AND STUDY AIMS: Stepwise circumferential and focal ablation of nondysplastic Barrett's esophagus has proven safe and effective. This study assessed the efficacy and safety of ablation for Barrett's esophagus with high-grade dysplasia (HGD), and residual Barrett's esophagus with dysplasia

  17. Association of left ventricular longitudinal and circumferential systolic dysfunction with diastolic function in hypertension: a nonlinear analysis focused on the interplay with left ventricular geometry.

    Science.gov (United States)

    Ballo, Piercarlo; Nistri, Stefano; Cameli, Matteo; Papesso, Barbara; Dini, Frank Lloyd; Galderisi, Maurizio; Zuppiroli, Alfredo; Mondillo, Sergio

    2014-02-01

    The relationships of left ventricular (LV) longitudinal and circumferential systolic dysfunction with diastolic performance in hypertensive patients have never been compared. In 532 asymptomatic hypertensive patients, circumferential function was assessed with the use of midwall fractional shortening (mFS) and stress-corrected mFS (SCmFS), whereas longitudinal function was assessed with the use of left atrioventricular plane displacement (AVPD) and systolic mitral annulus velocity (s'). Early diastolic annular velocity (e') and the E/e' ratio were measured. Global longitudinal and circumferential strain were determined in a subset of 210 patients. e' was linearly related to all systolic indexes (AVPD: R = 0.40; s': R = 0.39; mFS: R = 0.16; SCmFS: R = 0.17; all P SCmFS. Longitudinal indexes were superior to circumferential ones in predicting e' <8 cm/s, E/e' <8, and E/e' ≥13. The effect of LV geometry on LV diastolic function was evident among patients with preserved systolic longitudinal function, but was blunted among patients with impaired longitudinal function. In multivariable analyses, only longitudinal indexes remained associated with e' and E/e'. Analyses using strains provided similar results. In asymptomatic hypertensive subjects, LV diastolic performance is independently associated with longitudinal systolic dysfunction, but not with circumferential systolic dysfunction. Subtle longitudinal systolic impairment plays a role in mediating the effect of LV geometry on diastolic performance. These findings may support the need of critically revising the concept of isolated diastolic dysfunction in these patients. Copyright © 2014 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

    Chadwick, W.W.; Jonsson, Sigurjon; Geist, Dennis J.; Poland, M.; Johnson, Daniel J.; Batt, S.; Harpp, Karen S.; Ruiz, A.

    2011-01-01

    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.

  19. Degradation of microbial polyesters.

    Science.gov (United States)

    Tokiwa, Yutaka; Calabia, Buenaventurada P

    2004-08-01

    Microbial polyhydroxyalkanoates (PHAs), one of the largest groups of thermoplastic polyesters are receiving much attention as biodegradable substitutes for non-degradable plastics. Poly(D-3-hydroxybutyrate) (PHB) is the most ubiquitous and most intensively studied PHA. Microorganisms degrading these polyesters are widely distributed in various environments. Although various PHB-degrading microorganisms and PHB depolymerases have been studied and characterized, there are still many groups of microorganisms and enzymes with varying properties awaiting various applications. Distributions of PHB-degrading microorganisms, factors affecting the biodegradability of PHB, and microbial and enzymatic degradation of PHB are discussed in this review. We also propose an application of a new isolated, thermophilic PHB-degrading microorganism, Streptomyces strain MG, for producing pure monomers of PHA and useful chemicals, including D-3-hydroxycarboxylic acids such as D-3-hydroxybutyric acid, by enzymatic degradation of PHB.

  20. Automated assessments of circumferential strain from cine CMR correlate with LVEF declines in cancer patients early after receipt of cardio-toxic chemotherapy.

    Science.gov (United States)

    Jolly, Marie-Pierre; Jordan, Jennifer H; Meléndez, Giselle C; McNeal, Gary R; D'Agostino, Ralph B; Hundley, W Gregory

    2017-08-02

    In patients with cancer receiving potentially cardio-toxic chemotherapy, measurements of left ventricular (LV) circumferential or longitudinal strain are often used clinically to identify myocardial dysfunction. Using a new software algorithm, we sought to determine in individuals receiving treatment for cancer the association between automated assessments of LV mean mid-wall circumferential strain and conventional measures of LV ejection fraction (EF) both obtained from cardiovascular magnetic resonance (CMR) cine balanced steady-state free-precession (bSSFP) white-blood acquisitions. Before and 3 months after initiating treatment with potentially cardio-toxic chemotherapy, 72 individuals (aged 54 ± 14 years with breast cancer [39%], lymphoma [49%], or sarcoma [12%]) underwent serial CMR cine bSSFP assessments of LV volumes and EF, and mean mid-wall circumferential strain determined from these same cine images as well as from additional tagged CMR images. On the cine images, assessments of strain were obtained using the newly developed deformation-based segmentation algorithm. Assessments of LV volumes/EF from the cine images and strain from tagged CMR were accomplished using commercially available software. All measures were analyzed in a blinded fashion independent of one another. Acceptable measures for the automated assessments of mean mid-wall circumferential strain from the cine images were obtained in 142 of 144 visits (98.6%) with an overall analysis time averaging 6:47 ± 1:06 min. The results from these automated measures averaged -18.8 ± 2.9 at baseline and -17.6 ± 3.1 at 3 months (p = 0.001). Left ventricular EF declined slightly from 65 ± 7% at baseline to 62 ± 7% at 3 months (p = 0.0002). The correlation between strain from cine imaging and LVEF was r = -0.61 (p cine and tagged derived assessments of strain was r = 0.23; p = 0.01. Automated measures of LV mean mid-wall circumferential strain can be obtained in 6

  1. The influence of circumferential resection margin status on loco-regional recurrence in esophageal squamous cell carcinoma.

    Science.gov (United States)

    Park, Hae Jin; Kim, Hak Jae; Chie, Eui Kyu; Kang, Chang Hyun; Kim, Young Tae

    2013-06-01

    To analyze treatment outcomes and patterns of recurrence, and to examine the impact of adjuvant postoperative radiotherapy (PORT) after esophagectomy in esophageal squamous cell carcinoma (SqCC) regarding the status of circumferential resection margin (CRM). We performed a retrospective review of esophageal cancer patients operated in Seoul National University Hospital between 2003 and 2010. Pathologically proven T3 SqCC patients with written reports mentioning the status of CRM were selected. Fifty-nine out of 71 patients (83.1%) had CRM+. Twenty-eight patients had radiotherapy in CRM+ and CRM-, respectively. The median follow-up period was 17.1 months (range: 5.2-63.1). Median survival and 2-year overall survival were 13.8 months and 41.9% in CRM+, and 27.3 months and 74.1% in CRM-, respectively. Loco-regional relapse-free survival (LRRFS) rate at 2 years was 33.6% and 74.1% in each groups (P = 0.029). Loco-regional recurrence was the major pattern of failure in CRM+. PORT did not improve LRRFS. The esophageal SqCC patients with CRM+ after resection showed worse LRRFS. This finding validated the prognostic value of CRM status. Nevertheless, we failed to demonstrate the benefits of adjuvant PORT in CRM+. This might suggest the necessity of neoadjuvant therapy to decrease the CRM+ rate after esophagectomy. Copyright © 2012 Wiley Periodicals, Inc.

  2. Lack of independent significance of a close (<1 mm) circumferential resection margin involvement in esophageal and junctional cancer.

    Science.gov (United States)

    O'Farrell, N J; Donohoe, C L; Muldoon, C; Costelloe, J M; King, S; Ravi, N; Reynolds, J V

    2013-08-01

    For rectal cancer, an involved circumferential resection margin (CRM), defined as tumor cells within 1 mm of the CRM, is of established prognostic significance. This definition for the esophagus, however, is controversial, with the UK Royal College of Pathologists (RCP) recommending the 1 mm definition, while the College of American Pathologists (CAP) advises that only tumor cells at the cut margin (0 mm) define an incomplete (R1) resection. The aim of this study was to compare the clinical significance of both definitions in patients with pT3 tumors. CAP- and RCP-defined CRM status in patients treated by surgery only or by multimodal therapy was recorded prospectively in a comprehensive database from May 2003 to May 2011. Kaplan-Meier survival curves were generated, and factors affecting survival were assessed by univariate and multivariate analysis. A total of 157 of 340 patients had pT3 esophageal tumors, with RCP-positive CRM in 60 %, and 18 % by CAP. There were no significant differences between RCP-positive CRM and negative margins for node-positive disease, local recurrence, and survival. CAP-positive CRM was associated with positive nodes (P = 0.036) and poorer survival (P = 0.023). Multivariate analysis revealed nodal invasion to be the only independent prognostic variable (P = 0.004). A CRM margin of CRM.

  3. Studies on the behavior of part-through circumferential crack at intrados in elbows under in-plane bending moment

    International Nuclear Information System (INIS)

    Srivastava, A.; Prabhakaran, K.M.; Ghosh, A.K.

    2011-01-01

    Highlights: → Behavior of cracked elbows with part-through crack at intrados under bending moment is studied. → Some part of crack always opens and some part gets closed irrespective of mode of applied moment. → Fraction of the crack that opens basically decides the weakening effect of the cracked elbow. → Results will be useful for fracture studies and limit load estimation especially for LBB. - Abstract: This paper presents the behavior of part-through circumferential crack at intrados in elbows under in-plane bending moment. This is based on detailed non-linear (both material and geometric) finite element analysis performed on various sizes of elbows (generally used in piping industry), having different crack sizes. It is observed that some part of the crack always opens and some part gets closed irrespective of the mode of applied bending moment (opening/closing). The fraction of the crack that opens basically decides the weakening effect of the cracked elbow. It is observed that there is a threshold value of crack length and crack depth, before which no crack opening is observed under opening mode. Also as elbow becomes thinner, the threshold value of above two parameters increases. Quite interestingly, the part of crack which closes in opening mode opens under closing mode. The above mentioned study on the behavior of crack will be useful for fracture studies and limit load estimation especially when leak before break concept is to be employed.

  4. Circumferential welding applied for inox steel super duplex UNS S32750 using the process MIG using CMT® control

    International Nuclear Information System (INIS)

    Invernizzi, Bruno Pizol

    2017-01-01

    This study carried out circumferential welding experiments in UNS S32750 Super Duplex Stainless Steel tubes using diameters of 19,05 mm and 48,20 mm. Welds were performed using various welding parameters on a MIG machine with Cold Metal Transfer® CMT control. The weld joints were evaluated by visual and dimensional inspection in addition to the Vickers microhardness and traction tests, as well as the microstructural analysis in conjunction with phase precipitation analysis, which was performed according to practice A of ASTM A923, and corrosion test in accordance with practice A of ASTM G48 in conjunction with ASTM A923. The results indicated that welds performed in pipes with a diameter of 19.05 mm showed a weld joint with unacceptable dimensions according to the standard, this condition being attributed the use of a high wire diameter for the welding conditions used. Welding performed for pipes with a diameter of 48.20 mm showed a lack of penetration under the conditions employed when welded by the conventional CMT® process. In the case of the use of CMT® combined with pulsed arc, under conditions that generated greater heat input during welding, this resulted in total penetration of the joint and adequate surface finish. The results indicated that welding using the CMT® process combined with pulsed arc, under the conditions (parameters) employed generated good surface finish, combined mechanical properties, meeting standards requirements, as well as a balanced microstructure and high resistance to corrosion. (author)

  5. 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.

  6. Crack opening displacement of circumferential through-wall cracked cylinders subjected to tension and in-plane bending loads

    International Nuclear Information System (INIS)

    Yoo, Yeon-Sik

    2003-01-01

    This study is concerned with crack opening displacements (CODs) of cylinders with a circumferential through-crack which is subjected to tension and in-plane bending loads. Most studies about crack opening behavior have performed on membrane and global bending stresses. Moreover, they cannot be valid for large-scale structures. For simplicity on evaluation for structural integrity, crack opening displacement has been often calculated by plate or pipe model considering almost stresses as a membrane component. However, it is important to investigate ones close to real crack opening behaviors under stress states for reliability on evaluation. The results must be directly related to evaluate leakage detection in reactor vessel and the primary piping system of FBR structures. From that purpose, a series of FEM analyses were performed, and hence the characteristics of COD under an in-plane bending stress were compared with those under a membrane stress. In addition, the plate model was indicated to be unreasonable for application on large-scale pipes by comparing the plate model with the pipe model. The results of this study are expected to be valid for leakage evaluation of high temperature structures especially. (author)

  7. An assessment of composite repair system in offshore platform for corroded circumferential welds in super duplex steel pipe

    Directory of Open Access Journals (Sweden)

    Silvio de Barros

    2018-04-01

    Full Text Available The main aim of this study is to assess the effectiveness of a composite repair system in severely corroded circumferential welds in super duplex stainless steel pipes as a preventive measure against the premature corrosion damage at the welds. Artificial defects were fabricated on the super duplex steel tube in order to reproduce the localized corrosion damage defects found in real welded joints. Three kinds of through thickness defects were considered: 25%, 50% and 96% of the perimeter of the pipe. The performance of the repaired pipe was assessed by hydrostatic tests as per ISO 24817 standard. The results showed that the composite repair system can sustain the designed failure pressure even for the pipe damaged with through-wall defect up to 96% of the perimeter of the pipe. Hence, the composite repair system can be used as a preliminary tool to protect the unexpected or premature failure at the welds and maintain an adequate level of mechanical strength for a given operating pressure. This composite repair system can assure that the pipe will not leak until a planned maintenance of the line. Nevertheless, further work is still desirable to improve the confidence in the long-term performance of bonded composite

  8. High-grade spondylolisthesis: gradual reduction using Magerl's external fixator followed by circumferential fusion technique and long-term results.

    Science.gov (United States)

    Karampalis, Christos; Grevitt, Michael; Shafafy, Masood; Webb, John

    2012-05-01

    To report the results of a cohort of patients treated with this technique high lighting radiological and functional outcomes, discussing also benefits arising from a gradual reduction procedure compared with other techniques. We evaluated nine patients who have undergone high-grade listhesis reduction and circumferential fusion at our institution from 1988 to 2006. Average length of follow-up was 11 years (5-19). Functional outcomes and radiological measurements were recorded and reported. Slip magnitude was reduced by an average of 2.9 grades (Meyerding classification). Slip angle improved by an average of 66% (p = 0.0001), lumbosacral angle by 47% (p = 0.0002), sacral rotation by 51% (p = 0.0068) and sacral inclination by 47% (p = 0.0055). At the latest follow-up 88.9% had achieved solid fusion. Post-operative 10-point Visual Analogue Score (VAS) for back pain had improved by 70% (p Average postoperative Oswestry Disability Index for all patients was 8% (range 0-16%) and that for Low Back Outcome Scores was 56.6 (range 44-70). All components of Short Form 36 Health Survey were greater than 80%. Overall patients' expectations were met in 100%. This is an effective and safe technique which addresses the lumbosacral kyphosis and cosmetic deformity without the neurological complications which accompany other reduction and fusion techniques for high-grade spondylolisthesis.

  9. Blade row dynamic digital compression program. Volume 2: J85 circumferential distortion redistribution model, effect of Stator characteristics, and stage characteristics sensitivity study

    Science.gov (United States)

    Tesch, W. A.; Steenken, W. G.

    1978-01-01

    The results of dynamic digital blade row compressor model studies of a J85-13 engine are reported. The initial portion of the study was concerned with the calculation of the circumferential redistribution effects in the blade-free volumes forward and aft of the compression component. Although blade-free redistribution effects were estimated, no significant improvement over the parallel-compressor type solution in the prediction of total-pressure inlet distortion stability limit was obtained for the J85-13 engine. Further analysis was directed to identifying the rotor dynamic response to spatial circumferential distortions. Inclusion of the rotor dynamic response led to a considerable gain in the ability of the model to match the test data. The impact of variable stator loss on the prediction of the stability limit was evaluated. An assessment of measurement error on the derivation of the stage characteristics and predicted stability limit of the compressor was also performed.

  10. Influence of circumferential notch and fatigue crack on the mechanical integrity of biodegradable magnesium-based alloy in simulated body fluid.

    Science.gov (United States)

    Bobby Kannan, M; Singh Raman, R K; Witte, F; Blawert, C; Dietzel, W

    2011-02-01

    Applications of magnesium alloys as biodegradable orthopaedic implants are critically dependent on the mechanical integrity of the implant during service. In this study, the mechanical integrity of an AZ91 magnesium alloy was studied using a constant extension rate tensile (CERT) method. The samples in two different geometries that is, circumferentially notched (CN), and circumferentially notched and fatigue cracked (CNFC), were tested in air and in simulated body fluid (SBF). The test results show that the mechanical integrity of the AZ91 magnesium alloy decreased substantially (∼50%) in both the CN and CNFC samples exposed to SBF. Fracture surface analysis revealed secondary cracks suggesting stress corrosion cracking susceptibility of the alloy in SBF. Copyright © 2010 Wiley Periodicals, Inc.

  11. Circumferential bone loss around splinted and nonsplinted immediately loaded implants retaining mandibular overdentures: A randomized controlled clinical trial using cone beam computed tomography.

    Science.gov (United States)

    Elsyad, Moustafa Abdou; Khirallah, Ahmed Samir

    2016-11-01

    Circumferential marginal bone around 2 splinted and nonsplinted immediately loaded implants in the edentulous mandible has not been previously investigated. The purpose of this randomized controlled clinical trial was to assess circumferential bone loss around splinted and nonsplinted immediately loaded implants retaining mandibular overdentures, using cone beam computed tomography (CBCT). Thirty participants with complete edentulism were allocated to 2 groups and received 2 implants in the canine region of the mandible. Implants were either left nonsplinted (with ball attachment [BA]) or splinted (with bar attachment [RA]). Mandibular overdentures were connected to the implants 1 week later. CBCT was used to evaluate vertical bone loss (VBL) and horizontal bone loss (HBLo) bone loss at the distal (D), buccal (B), mesial (M), and lingual (L) sites of each implant upon overdenture insertion (baseline, T0), 1 year (T1) and 3 years (T3) after insertion. Repeated measures ANOVA was used for statistical analysis (α=.05). No significant difference in the survival rate (93.3% for BA and 100% for RA) was found between groups (P=.156). VBL and HBLo increased significantly at T3 compared with T1 for both groups (Poverdentures were associated with significantly higher vertical and horizontal circumferential bone loss than those associated with splinted implants after a follow-up of 3 years. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  12. Degradations and Rearrangement Reactions

    Science.gov (United States)

    Zhang, Jianbo

    This section deals with recent reports concerning degradation and rearrangement reactions of free sugars as well as some glycosides. The transformations are classified in chemical and enzymatic ways. In addition, the Maillard reaction will be discussed as an example of degradation and rearrangement transformation and its application in current research in the fields of chemistry and biology.

  13. 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

  14. Crack-tip constraint analyses and constraint-dependent LBB curves for circumferential through-wall cracked pipes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y.L.; Wang, G.Z., E-mail: gzwang@ecust.edu.cn; Xuan, F.Z.; Tu, S.T.

    2015-04-15

    Highlights: • Solution of constraint parameter τ* for through-wall cracked pipes has been obtained. • Constraint increases with increasing crack length and radius–thickness ratio of pipes. • Constraint-dependent LBB curve for through-wall cracked pipes has been constructed. • For increasing accuracy of LBB assessments, constraint effect should be considered. - Abstract: The leak-before-break (LBB) concept has been widely applied in the structural integrity assessments of pressured pipes in nuclear power plants. However, the crack-tip constraint effects in LBB analyses and designs cannot be incorporated. In this paper, by using three-dimensional finite element calculations, the modified load-independent T-stress constraint parameter τ* for circumferential through-wall cracked pipes with different geometries and crack sizes has been analyzed under different loading conditions, and the solutions of the crack-tip constraint parameter τ* have been obtained. Based on the τ* solutions and constraint-dependent J–R curves of a steel, the constraint-dependent LBB (leak-before-break) curves have been constructed. The results show that the constraint τ* increases with increasing crack length θ, mean radius R{sub m} and radius–thickness ratio R{sub m}/t of the pipes. In LBB analyses, the critical crack length calculated by the J–R curve of the standard high constraint specimen for pipes with shorter cracks is over-conservative, and the degree of conservatism increases with decreasing crack length θ, R{sub m} and R{sub m}/t. Therefore, the constraint-dependent LBB curves should be constructed to modify the over-conservatism and increase accuracy of LBB assessments.

  15. Evaluation of diagnostic efficiency of intelligence program for automatic diagnosis of circumferential profiles of myocardial short axial SPECT

    International Nuclear Information System (INIS)

    Bunko, Hisashi; Tada, Akira; Nakajima, Kenichi; Taki, Junichi; Kojima, Kazuhiko.

    1984-01-01

    Quantitative diagnosis using circumferential profile (CFP) is widely employed for Tl-201 myocardial imaging. However, its diagnostic efficiency is susceptible to the number and composition of the confirmed normal (CN) group. Intelligence program for CFP data file and automatic diagnosis (CAD), which was previously developed by us, was modified for creating universal data file (d-base) and evaluated its diagnostic efficiency for myocardial short axial images according to the number of CNs. CAD consists of following 3 major functions: (1) CFP data filing to d-base, (2) modification and correction of file data, and (3) automatic diagnosis of CFP. When function (1) or (2) is completed, new diagnostic criteria (mean-2 sd) are generated automatically using CN data in the d-base at that time. Because of this function, diagnostic criteria are changeable according to the number of CNs. Sensitivity (TP) and specificity (TN) of CAD program for Tl-201 7-pinhole images of 16 normals and 17 ischemic heart diseases (IHDs) were 100%, 44% (CN = 4), 88%, 94% (CN = 8 or 16) and 88%, 100% (CN = 12), respectively. Diagnostic efficiency reached plateau in more than 8 CNs. Although number of patients were limited (8 CNs and 6 IHDs), results of CAD for short axial SPECT showed consistent tendency with 7-pinhole images. In conclusion, intelligence program is necessary for automatic diagnosis using quantitative criteria under the clinical condition of daily increasing informations. Automatic diagnosis of CFP using CAD program is simple, effective and useful for interpretation of Tl-201 myocardial short axial images. CAD program is applicable to any quantitative distribution study using CFPs. (author)

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

    International Nuclear Information System (INIS)

    Iannicelli, Elsa; Di Renzo, Sara; Ferri, Mario; Pilozzi, Emanuela; Di Girolamo, Marco; Sapori, Alessandra; Ziparo, Vincenzo; David, Vincenzo

    2014-01-01

    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

  17. 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.

  18. Circumferential margin involvement after total mesorectal excision for mid or low rectal cancer: are all R1 resections equal?

    Science.gov (United States)

    Beaufrère, A; Guedj, N; Maggiori, L; Patroni, A; Bedossa, P; Panis, Y

    2017-11-01

    Our aim was to assess the prognostic influence of the circumferential resection margin (CRM) exact value after total mesorectal excision for mid or low rectal cancer. All patients (n = 321) who underwent total mesorectal excision from 2005 to 2013 were identified from a prospective database, including 49 (15%) who presented with a CRM ≤ 1 mm. Four groups were defined: group 1, CRM = 0 mm (n = 21); group 2, 0 CRM ≤ 0.4 mm (n = 13); group 3, 0.4 CRM ≤ 1 mm (n = 15); group 4, CRM > 1 mm (n = 272). After a mean follow-up of 42 ± 26 months, locoregional recurrence rates were 8/21 (38%) in group 1, 3/13 (23%) in group 2, 0/12 (0%) in group 3 and 26/272 (10%) in group 4 (P CRM ≤ 0.4 mm was identified as an independent factor impairing both locoregional recurrence-free survival (OR 3.14, 95% CI 1.53-6.46; P = 0.002) and disease-free survival (OR 2.15, 95% CI 1.28-3.63; P = 0.004). Our study suggests that the prognosis after mid or low rectal cancer surgery was worse with a CRM ≤ 0.4 mm. The prognosis was similar in patients with a CRM > 0.4 mm or ≤ 1 mm and patients with an R0 resection. Colorectal Disease © 2017 The Association of Coloproctology of Great Britain and Ireland.

  19. 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.

  20. Combined Circumferential and Longitudinal Left Ventricular Systolic Dysfunction in Patients with Rheumatoid Arthritis without Overt Cardiac Disease.

    Science.gov (United States)

    Cioffi, Giovanni; Viapiana, Ombretta; Ognibeni, Federica; Dalbeni, Andrea; Gatti, Davide; Mazzone, Carmine; Faganello, Giorgio; Di Lenarda, Andrea; Adami, Silvano; Rossini, Maurizio

    2016-07-01

    Patients with rheumatoid arthritis have an increased risk for cardiovascular disease. Because of accelerated atherosclerosis and changes in left ventricular (LV) geometry, circumferential and longitudinal (C&L) LV systolic dysfunction (LVSD) may be impaired in these patients despite preserved LV ejection fraction. The aim of this study was to determine the prevalence of and factors associated with combined C&L LVSD in patients with rheumatoid arthritis. One hundred ninety-eight outpatients with rheumatoid arthritis without overt cardiac disease were prospectively analyzed from January through June 2014 and compared with 198 matched control subjects. C&L systolic function was evaluated by stress-corrected midwall shortening (sc-MS) and tissue Doppler mitral annular peak systolic velocity (S'). Combined C&L LVSD was defined if sc-MS was cite either of them in the other one and, afterward, we just did not think about this point anymore. Of note, the idea to combine in the analysis longitudinal function came therefore well after the starting process of revision of the paper E and was, in some way inspired by a reviewer's comment. That is why we did not put both findings in the same paper. We think that our explanations provide the broad audience of your journal a perspective of transparency and our respect for the readers' right to understand how the work described in the paper J relates to other work by our research group. Giovanni Cioffi On behalf of all co-authors Ombretta Viapiana, Federica Ognibeni, Andrea Dalbeni, Davide Gatti, Carmine Mazzone, Giorgio Faganello, Andrea Di Lenarda, Silvano Adami, and Maurizio Rossini. Copyright © 2016 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.

  1. 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.

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

    KAUST Repository

    Chadwick, William W Jr; Jonsson, Sigurjon; Geist, Dennis J.; Poland, Michael P.; Johnson, Daniel J.; Batt, Spencer; Harpp, Karen S.; Ruiz, André s Gorki

    2010-01-01

    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.

  3. 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.

  4. Improved circumferential shaft seal

    Science.gov (United States)

    Ludwig, L. P.; Strom, T. N.

    1974-01-01

    Comparative tests of modified and unmodified carbon ring seals showed that addition of helical grooves to conventional segmented carbon ring seals reduced leakage significantly. Modified seal was insensitive to shaft runout and to flooding by lubricant.

  5. 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.

  6. Purex diluent degradation

    International Nuclear Information System (INIS)

    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 3 system is consistent with the active chemical agent being a radical-like nitrogen dioxide (NO 2 ) molecule, not HNO 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 3 concentration and the temperature. The rate was decreased by argon sparging to remove NO 2 and by the addition of butanol, which probably acts as a NO 2 scavenger. 13 references, 11 figures

  7. 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.

  8. Evaluation of circumferential angle closure using iridotrabecular contact index after laser iridotomy by swept-source optical coherence tomography.

    Science.gov (United States)

    Cho, Hyun-Kyung; Ahn, Dongsub; Kee, Changwon

    2017-05-01

    To investigate the quantitative changes of circumferential angle closure after laser iridotomy (LI) using the iridotrabecular contact (ITC) index by Swept-Source optical coherence tomography (OCT). In this prospective observational study conducted in a hospital setting, 42 eyes of 36 patients (five males, 31 females) who underwent LI were included. The mean age was 65.00 ± 8.13 years old and the diagnosis included primary angle closure (PAC, 21 eyes), PAC suspect (16 eyes) and PAC glaucoma (five eyes). Optical coherence tomography (OCT) images were obtained pre-LI and at 1 week post-LI. In each image frame, the scleral spur (SS) and the ITC end-point were marked, from which the ITC index was calculated as a percentage of the angle closure across 360°. Measurements inspected before and after LI included: central anterior chamber depth (ACD), anterior chamber volume (ACV), lens vault (LV), nasal and temporal angle opening distance (AOD), angle recess area (ARA), trabecular-iris space area (TISA), trabecular-iris angle (TIA) at 500 μm and 750 μm from the SS and intraocular pressure (IOP). The ITC index and IOP decreased significantly after LI from 71.52 ± 26.29 to 35.31 ± 27.19 and from 20.64 ± 12.72 mmHg to 14.02 ± 3.49 mmHg, respectively (p  0.05), but ACV increased significantly after LI (p angle parameters except for nasal TIAs increased significantly after LI (all p angle showed a significant decrease after LI, but part of the angle closure was not relieved after LI. Other mechanisms besides pupillary block may play a role together in causing angle closure. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  9. The Combined Incremental Prognostic Value of LVEF, Late Gadolinium Enhancement, and Global Circumferential Strain Assessed by CMR.

    Science.gov (United States)

    Mordi, Ify; Bezerra, Hiram; Carrick, David; Tzemos, Nikolaos

    2015-05-01

    This study aimed to assess the incremental prognostic value of global circumferential strain (GCS), as measured using cardiac magnetic resonance (CMR) tagging, in addition to baseline clinical characteristics, left ventricular ejection fraction (LVEF), and late gadolinium enhancement (LGE), in the prediction of major adverse cardiovascular events (MACE) in an unselected cohort of patients. LVEF is a powerful predictor of mortality and is used for guiding treatment decisions. It is, however, subject to limitations. The value of GCS measured by CMR tagging in patients with suspected cardiac disease has not been fully explored despite its being considered as the gold standard noninvasive method of assessment of LV deformation. We prospectively evaluated data from 539 consecutive patients referred for CMR who underwent a CMR protocol that included cine imaging, tagging, and LGE. The primary endpoint was the prevalence of MACE, defined as a composite of all-cause mortality, heart failure-related hospitalization, and aborted sudden cardiac death. MACE occurred in 62 of 539 patients (11.5%) over a mean follow-up period of 2.2 years. History of ischemic heart disease (IHD) and beta-blocker use were both significant clinical predictors of adverse outcomes. All 3 CMR parameters were significant multivariate predictors of the primary outcome when added to significant clinical predictors (LVEF, hazard ratio [HR]: 0.96 [95% confidence interval [CI]: 0.94 to 0.99; p = 0.005]; presence of LGE, HR: 2.07 [95% CI: 1.03 to 4.14; p = 0.04]; GCS, HR: 1.11 [95% CI: 1.02 to 1.21; p = 0.041]). Global chi-square increased significantly with the addition of both LGE and GCS. Both the presence of LGE and reduced GCS had independent prognostic value in the overall cohort. Patients with LVEF ≥35% but LGE present and reduced GCS had a poor outcome similar to that in those with LVEF value. This measure could provide further risk stratification, especially in patients with mild LV impairment

  10. Assessment of circumferential angle-closure by the iris-trabecular contact index with swept-source optical coherence tomography.

    Science.gov (United States)

    Baskaran, Mani; Ho, Sue-Wei; Tun, Tin A; How, Alicia C; Perera, Shamira A; Friedman, David S; Aung, Tin

    2013-11-01

    To evaluate the diagnostic performance of the iris-trabecular contact (ITC) index, a measure of the degree of angle-closure, using swept-source optical coherence tomography (SSOCT, CASIA SS-1000, Tomey Corporation, Nagoya, Japan) in comparison with gonioscopy. Prospective observational study. A total of 108 normal subjects and 32 subjects with angle-closure. The SSOCT 3-dimensional angle scans, which obtain radial scans for the entire circumference of the angle, were performed under dark conditions and analyzed using customized software by a single examiner masked to the subjects' clinical details. The ITC index was calculated as a percentage of the angle that was closed on SSOCT images. First-order agreement coefficient (AC1) statistics and area under the receiver operating characteristic curve (AUC) analyses were performed for angle-closure on the basis of the ITC index in comparison with gonioscopy. Angle-closure on gonioscopy was defined as nonvisibility of posterior trabecular meshwork for at least 2 quadrants. Agreement of the ITC index with gonioscopically defined angle-closure was assessed using the AC1 statistic. Study subjects were predominantly Chinese (95.7%) and female (70.7%), with a mean age of 59.2 (standard deviation, 8.9) years. The median ITC index was 15.24% for gonioscopically open-angle eyes (n = 108) and 48.5% for closed-angle eyes (n = 32) (P = 0.0001). The agreement for angle-closure based on ITC index cutoffs (>35% and ≥50%) and gonioscopic angle-closure was 0.699 and 0.718, respectively. The AUC for angle-closure detection using the ITC index was 0.83 (95% confidence interval, 0.76-0.89), with an ITC index >35% having a sensitivity of 71.9% and specificity of 84.3%. The ITC index is a summary measure of the circumferential extent of angle-closure as imaged with SSOCT. The index had moderate agreement and good diagnostic performance for angle-closure with gonioscopy as the reference standard. Copyright © 2013 American Academy of

  11. Phrenic nerve injury: An underrecognized and potentially preventable complication of pulmonary vein isolation using a wide-area circumferential ablation approach.

    Science.gov (United States)

    Yong Ji, Sang; Dewire, Jane; Barcelon, Bernadette; Philips, Binu; Catanzaro, John; Nazarian, Saman; Cheng, Alan; Spragg, David; Tandri, Harikrishna; Bansal, Sandeep; Ashikaga, Hiroshi; Rickard, Jack; Kolandaivelu, Aravindan; Sinha, Sunil; Marine, Joseph E; Calkins, Hugh; Berger, Ronald

    2013-10-01

    Phrenic nerve injury (PNI) is a well-known, although uncommon, complication of pulmonary vein isolation (PVI) using radiofrequency energy. Currently, there is no consensus about how to avoid or minimize this injury. The purpose of this study was to determine how often the phrenic nerve, as identified using a high-output pacing, lies along the ablation trajectory of a wide-area circumferential lesion set. We also sought to determine if PVI can be achieved without phrenic nerve injury by modifying the ablation lesion set so as to avoid those areas where phrenic nerve capture (PNC) is observed. We prospectively enrolled 100 consecutive patients (age 61.7 ± 9.2 years old, 75 men) who underwent RF PVI using a wide-area circumferential ablation approach. A high-output (20 mA at 2 milliseconds) endocardial pacing protocol was performed around the right pulmonary veins and the carina where a usual ablation lesion set would be made. A total of 30% of patients had PNC and required modification of ablation lines. In the group of patients with PNC, the carina was the most common site of capture (85%) followed by anterior right superior pulmonary vein (RSPV) (70%) and anterior right inferior pulmonary vein (RIPV) (30%). A total of 25% of PNC group had capture in all 3 (RSPV, RIPV, and carina) regions. There was no difference in the clinical characteristics between the groups with and without PNC. RF PVI caused no PNI in either group. High output pacing around the right pulmonary veins and the carina reveals that the phrenic nerve lies along a wide-area circumferential ablation trajectory in 30% of patients. Modification of ablation lines to avoid these sites may prevent phrenic nerve injury during RF PVI. © 2013 Wiley Periodicals, Inc.

  12. Progress on the degraded piping program - Phase II. Battelle Columbus Division

    International Nuclear Information System (INIS)

    Wilkowski, Gery; Ahmad, J.; Barnes, C.; Brust, F.; Guerrieri, D.; Kramer, G.; Landow, M.; Marschall, C.; Nakagaki, M.; Papaspyropoulos; Scott, P.

    1988-01-01

    The overall objective of the Degraded Piping Program is to verify and improve simple estimation schemes to predict the fracture behavior of circumferentially cracked pipe. The program is limited to quasi-static fracture and cracks in straight pipe. There are a variety of materials, flaw geometries, pipe sizes, and loading conditions evaluated. The Degraded Piping Program,which has been extended for one more year, will supply results that provide a basis for regulatory decisions regard applications for leak-before-break (LBB) and In-service flaw assessment. The significance of our results are summarized relative to how they may affect regulatory technical needs. The scope of the work in The Degraded Piping Program includes both analytical and experimental efforts. The experimental efforts have concentrated on testing circumferentially cracked pipe at 550 F (288 C) under si-static loading. Many of the tasks within this program were undertaken with the objective of determining if any detailed efforts were needed. This is true for both the analytical and experimental efforts. i e of the tasks have been slightly expanded during the course of the gram, while others were found to be of lesser concern and further efforts in those areas were not pursued. The results of this summary include the efforts of the third year. These efforts have contributed considerably to the understanding of the application of elastic-plastic fracture mechanics to nuclear piping systems. Rather than listing the significant technical contributions, these contributions are summarized below in relation to their application to LBB analyses, in-service flaw assessment criteria, and (3) material characterization and unusual behavior of nuclear piping materials at light water reactor (LWR) temperatures

  13. Mis-Match Limit Load Analyses and Fracture Mechanics Assessment for Welded Pipe with Circumferential Crack at the Center of Weldment

    Energy Technology Data Exchange (ETDEWEB)

    Song, Tae Kwang; Jeon, Jun Young; Shim, Kwang Bo; Kim, Yun Jae [Korea University, Seoul (Korea, Republic of); Kim, Jong Sung [Sunchon University, Suncheon (Korea, Republic of); Jin, Tae Eun [Korea Power Engineering Company, Daejeon (Korea, Republic of)

    2010-01-15

    In this paper, limit load analyses and fracture mechanics analyses were conducted via finite element analyses for the welded pipe with circumferential crack at the center of the weldment. Systematic changes for strength mismatch ratio, width of weldment, crack shape and thickness ratio of the pipe were considered to provide strength mismatch limit load. And J-integral calculations based on reference stress method were conducted for two materials, stainless steel and ferritic steel. Reference stress defined by provided strength mis-match limit load gives much more accurate J-integral.

  14. Spontaneous slip reduction of low-grade isthmic spondylolisthesis following circumferential release via bilateral minimally invasive transforaminal lumbar interbody fusion: technical note and short-term outcome.

    Science.gov (United States)

    Pan, Jie; Li, Lijun; Qian, Lie; Zhou, Wei; Tan, Jun; Zou, Le; Yang, Mingjie

    2011-02-15

    STUDY DESIGN.: Retrospective clinical data analysis. OBJECTIVE.: To investigate and verify our philosophy of spontaneous slip reduction following circumferential release via bilateral minimally invasive transforaminal lumbar interbody fusion (Mini-TLIF) for treatment of low-grade symptomatic isthmic spondylolisthesis. SUMMARY OF BACKGROUND DATA.: Symptomatic isthmic spondylolisthesis usually requires surgical intervention, and the most currently controversial focus is on method and degree of reduction; and Mini-TLIF is an attractive surgical procedure for isthmic spondylolisthesis. METHODS.: Between February 2004 and June 2008, 21 patients with low-grade isthmic spondylolisthesis underwent Mini-TLIF in our institute. Total resection of the scar around the pars interarticularis liberated the nerve roots, achieving posterior release as well. The disc was thoroughly resected, and the disc space was gradually distracted and thoroughly released with sequential disc shavers until rupture of anulus conjunct with anterior longitudinal ligament, accomplishing anterior release, so as to insert Cages. Because of circumferential release, the slipped vertebrae would tend to obtain spontaneous reduction, and with pedicle screw fixation, additional reduction would be achieved without any application of posterior translation force. Radiographs, Visual Analogue Scale, and Oswestry Disability Index were documented. All the cases were followed up for 10 to 26 months. RESULTS.: Slip percentage was reduced from 24.2% ± 6.9% to 10.5% ± 4.0%, and foraminal area percentage increased from 89.1% ± 3.0% to 93.6% ± 2.1%. Visual Analogue Scale and Oswestry Disability Index decreased from 7.8 ± 1.5 to 2.1 ± 1.1 and from 53.3 ± 16.2 to 17.0 ± 7.8, respectively. No neurologic complications were encountered. There were no signs of instrumentation failure. The fusion rate approached 100%. CONCLUSION.: Slip reduction is based on circumferential release. The procedure can be well performed

  15. Drift Degradation Analysis

    International Nuclear Information System (INIS)

    D. Kicker

    2004-01-01

    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 stress. (3) The DRKBA

  16. 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

  17. Developments in polymer degradation - 7

    International Nuclear Information System (INIS)

    Grassie, N.

    1987-01-01

    A selection of topics which are representative of the continually expanding area of polymer degradation is presented. The aspects emphasised include the products of degradation of specific polymers, degradation by high energy radiation and mechanical forces, fire retardant studies and the special role of small radicals in degradation processes. (author)

  18. 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.

  19. Endocytic collagen degradation

    DEFF Research Database (Denmark)

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

    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...... 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...... groups of mice clearly revealed a fibrosis protective role of uPARAP/Endo180. This effect appeared to directly reflect the activity of the collagen receptor, since no compensatory events were noted when comparing the mRNA expression profiles of the two groups of mice in an array system focused on matrix-degrading...

  20. 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...... in the atmosphere to yield a homologous series of PFCAs. Atmospheric degradation of FTOHs is likely to contribute to the widespread dissemination of PFCAs. After their bioaccumulation potential is accounted for, the pattern of PFCAs yielded from FTOHs could account for the distinct contamination profile of PFCAs....... The significance of the gas-phase peroxy radical cross reactions that produce PFCAs has not been recognized previously. Such reactions are expected to occur during the atmospheric degradation of all polyfluorinated materials, necessitating a reexamination of the environmental fate and impact of this important...

  1. Motor degradation prediction methods

    International Nuclear Information System (INIS)

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

    1996-01-01

    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

  2. Ecosystem degradation in India

    International Nuclear Information System (INIS)

    Sinha, B.N.

    1990-01-01

    Environmental and ecosystem studies have assumed greater relevance in the last decade of the twentieth century than even before. The urban settlements are becoming over-crowded and industries are increasingly polluting the air, water and sound in our larger metropolises. Degradation of different types of ecosystem are discussed in this book, Ecosystem Degradation in India. The book has been divided into seven chapters: Introduction, Coastal and Delta Ecosystem, River Basin Ecosystem, Mountain Ecosystem, Forest Ecosystem, Urban Ecosystem and the last chapter deals with the Environmental Problems and Planning. In the introduction the environmental and ecosystem degradation problems in India is highlighted as a whole while in other chapters mostly case studies by experts who know their respective terrain very intimately are included. The case study papers cover most part of India and deal with local problems, stretching from east coast to west coast and from Kashmir to Kanyakumari. (author)

  3. PWR degraded core analysis

    International Nuclear Information System (INIS)

    Gittus, J.H.

    1982-04-01

    A review is presented of the various phenomena involved in degraded core accidents and the ensuing transport of fission products from the fuel to the primary circuit and the containment. The dominant accident sequences found in the PWR risk studies published to date are briefly described. Then chapters deal with the following topics: the condition and behaviour of water reactor fuel during normal operation and at the commencement of degraded core accidents; the generation of hydrogen from the Zircaloy-steam and the steel-steam reactions; the way in which the core deforms and finally melts following loss of coolant; debris relocation analysis; containment integrity; fission product behaviour during a degraded core accident. (U.K.)

  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. Detection of pump degradation

    International Nuclear Information System (INIS)

    Casada, D.A.

    1994-01-01

    There are a variety of stressors that can affect the operation of centrifugal pumps. These can generally be classified as: Mechanical; Hydraulic; Tribological; Chemical; and Other (including those associated with the pump driver). 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

  6. Global limit load solutions for thick-walled cylinders with circumferential cracks under combined internal pressure, axial force and bending moment − Part II: Finite element validation

    International Nuclear Information System (INIS)

    Li, Yuebing; Lei, Yuebao; Gao, Zengliang

    2014-01-01

    Global limit load solutions for thick-walled cylinders with circumferential internal/external surface and through-wall defects under combined positive/negative axial force, positive/negative global bending moment and internal pressure have been developed in Part I of this paper. In this Part II, elastic-perfectly plastic 3-D finite element (FE) analyses are performed for selected cases, covering a wide range of geometries and load combinations, to validate the developed limit load solutions. The results show that these limit load solutions can predict the FE data very well for the cases with shallow or deep and short cracks and are conservative. For the cases with very long and deep cracks, the predictions are reasonably accurate and more conservative. -- Highlights: • Elastic-perfectly plastic 3D finite element limiting analyses of cylinders. • Thin/thick-walled cylinders with circumferential surface defects. • Combined loading for pressure, end-force and global bending moment. • Totally 1458 cases analysed and tabulated normalised results provided. • Results used to validate the developed limit load solutions in Part I of this paper

  7. Anastomosis in the absence of a suprahyoid release following circumferential sleeve resection is feasible in differentiated thyroid carcinoma patients with tracheal invasion.

    Science.gov (United States)

    Chen, Wanjun; Zou, Shujuan; Wang, Liang; Wu, Changhua; Wang, Zhiqi; Li, Ke; Zhang, Shuguang

    2017-09-01

    Invasion of the trachea is observed in ~6% of patients with differentiated thyroid carcinoma (DTC), and surgery is accepted as the treatment of choice. However, surgical procedures can be challenging and are associated with various risks. The authors of the present study performed a retrospective study of patients with DTC and tumor invasion of the trachea. Outcomes from patients that received circumferential sleeve resection (CSR) of the trachea followed by anastomosis in the absence of suprahyoid release (n=21; CSR group) and patients that underwent tangential resections [n=103; tangential 'shave' resection (TSR) group) were analyzed. In the CSR group, 4 to 8 tracheal rings were circumferentially resected. All patients underwent end-to-end anastomosis in the absence of suprahyoid release following CSR, and 7 patients developed cancer metastasis following surgery. With the exception of 2 patients that succumbed to disease, the remaining patients in the CSR group survived without cancer recurrence. In the TSR group, all of the patients experienced cancer recurrence within five years post-surgery. A total of 61 patients developed metastases in the three years following surgery, and 71 patients succumbed to cancer metastasis within five years. The survival rate of the CSR group was significantly increased compared with the TSR group. The results of the present study suggest that in DTC patients with defects involving up to 8 tracheal rings, it may be appropriate to perform anastomosis without suprahyoid tissue release as it is associated with a reduced incidence of perioperative morbidity.

  8. Cerebral hemodynamic difference between early- and late-onset Alzheimer's disease by circumferential profile analysis with 123I-IMP brain SPECT

    International Nuclear Information System (INIS)

    Arai, Hisayuki; Hanyu, Haruo; Abe, Shinei; Asano, Tetsuichi; Takasaki, Masaru; Suzuki, Takanari; Abe, Kimihiko; Katsunuma, Hideyo.

    1992-01-01

    We conducted investigation to determine whether early- and late-onset Alzheimer's diseases differ pathophysiologically. Five patients with the early-onset (65 years and under) of the disease and 11 with the late-onset (65 years and over) of the disease were studied by single photon emission CT (SPECT) with N-isopropyl-p-[ 123 I]iodoamphetamine (IMP). Circumferential profile analysis (CPA) was performed to examine differences in the predominant hypoperfusion in the temporoparietal lobe, which is considered to be functionally damaged the most in Alzheimer's disease. The Xm values, calculated from gradients between the motorsensory or occipital cortices and temporoparietal cortex in the circumferential profile curve, were compared in both groups. The Xm values for patients with early- and late-onset Alzheimer's disease were 6.81±2.10 (counts/degree) and 3.28±1.58, respectively, the difference being significant. Our results suggest that functional abnormalities in the temporoparietal area severer in early- than late-onset Alzheimer's disease and that the application of CPA to IMP SPECT is useful to elucidate the pathophysiological difference between each of the disease. (author)

  9. Assessment of Myocardial Contractile Function Using Global and Segmental Circumferential Strain following Intracoronary Stem Cell Infusion after Myocardial Infarction: MRI Feature Tracking Feasibility Study

    International Nuclear Information System (INIS)

    Bhatti, Sabha; Al-Khalidi, Hussein; Hor, Kan; Hakeem, Abdul; Taylor, Michael; Quyyumi, Arshed A.; Oshinski, John; Pecora, Andrew L.; Kereiakes, Dean; Chung, Eugene; Pedrizzetti, Gianni; Miszalski-Jamka, Tomasz; Mazur, Wojciech

    2012-01-01

    Background. Magnetic resonance imaging (MRI) strain analysis is a sensitive method to assess myocardial function. Our objective was to define the feasibility of MRI circumferential strain (ε cc ) analysis in assessing subtle changes in myocardial function following stem cell therapy. Methods and Results. Patients in the Amorcyte Phase I trial were randomly assigned to treatment with either autologous bone-marrow-derived stem cells infused into the infarct-related artery 5 to 11 days following primary PCI or control. MRI studies were obtained at baseline, 3, and 6 months. ε cc was measured in the short axis views at the base, mid and apical slices of the left ventricle (LV) for each patient (13 treatments and 10 controls). Mid-anterior LV ε cc improved between baseline −18.5 ± 8.6 and 3 months −22.6 ± 7.0, P = 0.03. There were no significant changes in ε cc at 3 months and 6 months compared to baseline for other segments. There was excellent intraobserver and interobserver agreement for basal and mid circumferential strain. Conclusion. MRI segmental strain analysis is feasible in assessment of regional myocardial function following cell therapy with excellent intra- and inter-observer variability's. Using this method, a modest interval change in segmental ε cc was detected in treatment group

  10. Drift Degradation Analysis

    International Nuclear Information System (INIS)

    G.H. Nieder-Westermann

    2005-01-01

    The outputs from the drift degradation analysis support scientific analyses, models, and design calculations, including the following: (1) Abstraction of Drift Seepage; (2) Seismic Consequence Abstraction; (3) Structural Stability of a Drip Shield Under Quasi-Static Pressure; and (4) Drip Shield Structural Response to Rock Fall. This report has been developed in accordance with ''Technical Work Plan for: Regulatory Integration Modeling of Drift Degradation, Waste Package and Drip Shield Vibratory Motion and Seismic Consequences'' (BSC 2004 [DIRS 171520]). The drift degradation analysis includes the development and validation of rockfall models that approximate phenomenon associated with various components of rock mass behavior anticipated within the repository horizon. Two drift degradation rockfall models have been developed: the rockfall model for nonlithophysal rock and the rockfall model for lithophysal rock. These models reflect the two distinct types of tuffaceous rock at Yucca Mountain. The output of this modeling and analysis activity documents the expected drift deterioration for drifts constructed in accordance with the repository layout configuration (BSC 2004 [DIRS 172801])

  11. Bacterial Degradation of Pesticides

    DEFF Research Database (Denmark)

    Knudsen, Berith Elkær

    could potentially improve bioremediation of BAM. An important prerequisite for bioaugmentation is the potential to produce the degrader strain at large quantities within reasonable time. The aim of manuscript II, was to optimize the growth medium for Aminobacter MSH1 and to elucidate optimal growth...

  12. Radiation degradation of silk

    Energy Technology Data Exchange (ETDEWEB)

    Ishida, Kazushige; Kamiishi, Youichi [Textile Research Institute of Gunma, Kiryu, Gunma (Japan); Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2001-03-01

    Silk fibroin powder was prepared from irradiated silk fibroin fiber by means of only physical treatment. Silk fibroin fiber irradiated with an accelerated electron beam in the dose range of 250 - 1000 kGy was pulverized by using a ball mill. Unirradiated silk fibroin fiber was not pulverized at all. But the more irradiation was increased, the more the conversion efficiency from fiber to powder was increased. The conversion efficiency of silk fibroin fiber irradiated 1000 kGy in oxygen was 94%. Silk fibroin powder shows remarkable solubility, which dissolved 57% into water of ambient temperature. It is a very interesting phenomenon that silk fibroin which did not treat with chemicals gets solubility only being pulverized. In order to study mechanism of solubilization of silk fibroin powder, amino acid component of soluble part of silk fibroin powder was analyzed. The more irradiation dose up, the more glycine or alanine degraded, but degradation fraction reached bounds about 50%. Other amino acids were degraded only 20% even at the maximum. To consider crystal construction of silk fibroin, it is suggested that irradiation on silk fibroin fiber selectively degrades glycine and alanine in amorphous region, which makes it possible to pulverize and to dissolve silk fibroin powder. (author)

  13. Detection of pump degradation

    International Nuclear Information System (INIS)

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

    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

  14. 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.

  15. 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.

  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. Rapidly Degradable Pyrotechnic System

    Science.gov (United States)

    2009-02-01

    material system (structural polymer and degradation agent ) for producing a high strength, non-corroding, highly inert, environmentally safe, extended...polymer sites in the active enzyme center differs dramatically between alkyl and aromatic polyesters. More specifically, as the degree of backbone...capped and centrifuged at 3,000 g. This procedure was repeated twice. To the remaining biomass pellet 15 mL of 1 mg/mL solution of N-ethyl-N- nitrosourea

  18. Radiation degradation of chitosan

    International Nuclear Information System (INIS)

    Norzita Yacob; Maznah Mahmud; Norhashidah Talip; Kamarudin Bahari; Kamaruddin Hashim; Khairul Zaman Dahlan

    2010-01-01

    In order to obtain an oligo chitosan, degradation of chitosan s were carried out in solid state and liquid state. The effects of an irradiation on the molecular weight and viscosity of the chitosan were investigated using Ubbelohde Capillary Viscometer and Brookfield Viscometer respectively. The molecular weight and viscosity of the chitosan s were decreased with an increase in the irradiation dose. In the presence of hydrogen peroxide, the molecular weight of chitosan can be further decreased. (author)

  19. Detection of pump degradation

    International Nuclear Information System (INIS)

    Casada, D.

    1994-01-01

    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 spectral 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. 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. Detection of pump degradation

    International Nuclear Information System (INIS)

    Casada, D.

    1995-01-01

    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

  1. WEATHERABILITY OF ENHANCED DEGRADABLE PLASTICS

    Science.gov (United States)

    The main objective of this study was to assess the performance and the asociated variability of several selected enhanced degradable plastic materials under a variety of different exposure conditions. Other objectives were to identify the major products formed during degradation ...

  2. Michelin tire baby syndrome: a review of the literature and a proposal for diagnostic criteria with adoption of the name circumferential skin folds syndrome.

    Science.gov (United States)

    Rothman, Ilene L

    2014-01-01

    The term Michelin tire baby (MTB), named for the cartoon mascot of the Michelin Tire Company, has been used to describe babies with multiple symmetric circumferential rings of folded skin. In those reported with this phenotype who had skin biopsies, pathology has shown nevus lipomatosis, smooth muscle hamartoma, degenerative collagen, and scarring. Others did not undergo biopsy or had normal skin. Many individuals with the MTB phenotype have had a variety of other congenital anomalies. I review the literature on MTB and the history of the designation Michelin tire baby Syndrome (MTBS). Because the term MTBS has been poorly defined or not defined at all, I propose strict criteria for diagnosis. In doing so, it is recommended that the syndrome be renamed to avoid further confusion. © 2014 Wiley Periodicals, Inc.

  3. A new method to estimate left ventricular circumferential midwall systolic function by standard echocardiography: Concordance between models and validation by speckle tracking.

    Science.gov (United States)

    Ballo, Piercarlo; Nistri, Stefano; Bocelli, Arianna; Mele, Donato; Dini, Frank L; Galderisi, Maurizio; Zuppiroli, Alfredo; Mondillo, Sergio

    2016-01-15

    Assessment of left ventricular circumferential (LVcirc) systolic function by standard echocardiography can be performed by estimating midwall fractional shortening (mFS) and stress-corrected mFS (ScmFS). Their determination is based on spherical or cylindrical LV geometric models, which often yield discrepant values. We developed a new model based on a more realistic truncated ellipsoid (TE) LV shape, and explored the concordance between models among hypertensive patients. We also compared the relationships of different mFS and ScmFS estimates with indexes of LVcirc systolic strain. In 364 hypertensive subjects, mFS was determined using the spherical (mFSspher), cylindrical (mFScyl), and TE model (mFSTE). Corresponding values of ScmFSspher, ScmFScyl, and ScmFSTE were obtained. Global circumferential strain (GCS) and systolic strain rate (GCSR) were also measured by speckle tracking. The three models showed poor concordance for the estimation of mFS, with average differences ranging between 11% and 30% and wide limits of agreement. Similar results were found for ScmFS, where reclassification rates for the identification of abnormal LVcirc systolic function ranged between 18% and 29%. When tested against strain indexes, mFSTE and ScmFSTE showed the best correlations (R=0.81 and R=0.51, p<0.0001 for both) with GCS and GCSR. Multivariable analysis confirmed that mFSTE and ScmFSTE showed the strongest independent associations with LVcirc strain measures. Substantial discrepancies in LVcirc midwall systolic indexes exist between different models, supporting the need of model-specific normative data. The use of the TE model might provide indexes that show the best associations with established strain measures of LVcirc systolic function. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  4. The circumferential resection margins status: A comparison of robotic, laparoscopic and open total mesorectal excision for mid and low rectal cancer.

    Science.gov (United States)

    de Jesus, J P; Valadão, M; de Castro Araujo, R O; Cesar, D; Linhares, E; Iglesias, A C

    2016-06-01

    Minimally invasive surgery for rectal cancer (RC) is now widely performed via the laparoscopic approach, but robotic-assisted surgery may overcome some limitations of laparoscopy in RC treatment. We compared the rate of positive circumferential margins between robotic, laparoscopic and open total mesorectal excision (TME) for RC in our institution. Mid and low rectal adenocarcinoma patients consecutively submitted to robotic surgery were compared to laparoscopic and open approach. From our prospective database, 59 patients underwent robotic-assisted rectal surgery from 2012 to 2015 (RTME group) were compared to our historical control group comprising 200 open TME (OTME group) and 41 laparoscopic TME (LTME group) approaches from July 2008 to February 2012. Primary endpoint was to compare the rate of involved circumferential resection margins (CRM) and the mean CRM between the three groups. Secondary endpoint was to compare the mean number of resected lymph nodes between the three groups. CRM involvement was demonstrated in 20 patients (15.5%) in OTME, 4 (16%) in LTME and 9 (16.4%) in the RTME (p = 0.988). The mean CRM in OTME, LTME and RTME were respectively 0.6 cm (0-2.7), 0.7 cm (0-2.0) and 0.6 cm (0-2.0) (p = 0.960). Overall mean LN harvest was 14 (0-56); 16 (0-52) in OTME, 13 (1-56) in LTME and 10 (0-45) in RTME (p = 0.156). Our results suggest that robotic TME has the same oncological short-term results when compared to the open and laparoscopic technique, and it could be safely offered for the treatment of mid and low rectal cancer. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. 球笼式等速万向节圆周间隙分析%Analysis on Circumferential Clearance of Rzeppa Constant Velocity Joint

    Institute of Scientific and Technical Information of China (English)

    黄钟灵; 郭常宁; 石宝枢

    2011-01-01

    针对球笼式等速万向节的结构与运动形式,建立了椭圆沟道截面圆周间隙的空间立体模型,推导了圆周间隙角θ在任意摆角和转角条件下的计算公式,使用Matlab软件研究了θ随摆角和转角变化的规律.结果表明:θ与椭圆沟道长、短半轴、钢球半径、钢球回转半径、偏心距、摆角以及转角有关,θ的6次波动是导致汽车行驶过程中振动和噪声的主要原因.%Based on structure and motion forms of rzeppa constant velocity joint,the three-dimensional model of circumferential clearance of elliptic section was established,and the formula of circumferential clearance angle(θ) at any swing angle and rotating angle was deduced,the changing law of θ with swing angle and rotating angle was obtained by using Matlab software.The results show that θ is related to the short and long half axle of the elliptical raceway,radius of steal ball,turning radius of steal ball,eccentricity,swing angle and rotating angle.The six fluctuations of θ lead to the vibration and noise during the travelling.

  6. A method for the measurement of dispersion curves of circumferential guided waves radiating from curved shells: experimental validation and application to a femoral neck mimicking phantom

    Science.gov (United States)

    Nauleau, Pierre; Minonzio, Jean-Gabriel; Chekroun, Mathieu; Cassereau, Didier; Laugier, Pascal; Prada, Claire; Grimal, Quentin

    2016-07-01

    Our long-term goal is to develop an ultrasonic method to characterize the thickness, stiffness and porosity of the cortical shell of the femoral neck, which could enhance hip fracture risk prediction. To this purpose, we proposed to adapt a technique based on the measurement of guided waves. We previously evidenced the feasibility of measuring circumferential guided waves in a bone-mimicking phantom of a circular cross-section of even thickness. The goal of this study is to investigate the impact of the complex geometry of the femoral neck on the measurement of guided waves. Two phantoms of an elliptical cross-section and one phantom of a realistic cross-section were investigated. A 128-element array was used to record the inter-element response matrix of these waveguides. This experiment was simulated using a custom-made hybrid code. The response matrices were analyzed using a technique based on the physics of wave propagation. This method yields portions of dispersion curves of the waveguides which were compared to reference dispersion curves. For the elliptical phantoms, three portions of dispersion curves were determined with a good agreement between experiment, simulation and theory. The method was thus validated. The characteristic dimensions of the shell were found to influence the identification of the circumferential wave signals. The method was then applied to the signals backscattered by the superior half of constant thickness of the realistic phantom. A cut-off frequency and some portions of modes were measured, with a good agreement with the theoretical curves of a plate waveguide. We also observed that the method cannot be applied directly to the signals backscattered by the lower half of varying thicknesses of the phantom. The proposed approach could then be considered to evaluate the properties of the superior part of the femoral neck, which is known to be a clinically relevant site.

  7. Statistical modeling for degradation data

    CERN Document Server

    Lio, Yuhlong; Ng, Hon; Tsai, Tzong-Ru

    2017-01-01

    This book focuses on the statistical aspects of the analysis of degradation data. In recent years, degradation data analysis has come to play an increasingly important role in different disciplines such as reliability, public health sciences, and finance. For example, information on products’ reliability can be obtained by analyzing degradation data. In addition, statistical modeling and inference techniques have been developed on the basis of different degradation measures. The book brings together experts engaged in statistical modeling and inference, presenting and discussing important recent advances in degradation data analysis and related applications. The topics covered are timely and have considerable potential to impact both statistics and reliability engineering.

  8. Radiation degradation of cellulose

    International Nuclear Information System (INIS)

    Leonhardt, J.; Arnold, G.; Baer, M.; Langguth, H.; Gey, M.; Huebert, S.

    1985-01-01

    The application of straw and other cellulose polymers as feedstuff for ruminants is limited by its low digestibility. During recent decades it was attempted to increase the digestibility of straw by several chemical and physical methods. In this work some results of the degradation of gamma and electron treated wheat straw are reported. Complex methods of treatment are taken into consideration. In vitro-experiments with radiation treated straw show that the digestibility can be increased from 20% up to about 80%. A high pressure liquid chromatography method was used to analyze the hydrolysates. The contents of certain species of carbohydrates in the hydrolysates in dependence on the applied dose are given. (author)

  9. Chemical degradation of pentachlorophenol

    International Nuclear Information System (INIS)

    Shukla, S.S.; Shukla, A.; Chandrasekharaiah, M.S.

    1992-01-01

    Industry produces a large volume of hazardous wastes containing pentachlorophenol, a U.S. EPA priority hazardous organic material. The environmentally safe disposal of these PCP-contaminated wastes is a serious problem for the waste management authorities as the current treatment processes are unsatisfactory. In this paper, the results of a feasibility study of chemical degradation and/or solidification methods for PCP-containing wastes. The photochemical decomposition of the PCP in a microemulsion or in micellar media obtained with the help of SDS or CTAB show the greatest promise

  10. Radiation degradation of polymethacrylamide

    International Nuclear Information System (INIS)

    O'Connor, D.J.

    1984-01-01

    The effects of radiation on polymers have been studied for many years. When polymers are subjected to ultraviolet light or ionizing radiation, chain scission and crosslinking are possible. The radiation degradations of several methacrylate type polymers were investigated. The primary polymer studied was polymethacrylamide (PMAAm). Ultraviolet irradiated PMAAm yielded a five line ESR spectrum with 22 gauss splitting which is believed to arise from a polymeric radical ending with a methacrylamide unit. The results obtained indicate that polymethacrylamide is a polymer which undergoes main chain cleavage upon irradiation. As such this polymer may have potential applicability as a positive resist for fabrication of microelectronic devices

  11. Probabilistic procedure to evaluate integrity of degraded pipes under internal pressure and bending moment

    International Nuclear Information System (INIS)

    Roos, E.; Herter, K.-H.; Julisch, P.; Otremba, F.; Schuler, X.

    2003-01-01

    The determination of critical crack sizes or permissible/allowable loading levels in pipes with degraded pipe sections (circumferential cracks) for the assurance of component integrity is usually based on deterministic approaches. Therefore along with numerical calculational methods (finite element (FE) analyses) limit load calculations, such as e.g. the 'Plastic limit load concept' and the 'Flow stress concept' as well as fracture mechanics approximation methods as e.g. the R-curve method or the 'Ductile fracture handbook' and the R6-Method are currently used for practical application. Numerous experimental tests on both ferritic and austenitic pipes with different pipe dimensions were investigated at MPA Stuttgart. The geometries of the pipes were comparable to actual piping systems in Nuclear Power Plants, both BWR as well as PWR. Through wall cracks and part wall through cracks on the inside surface of the pipes were considered. The results of these tests were used to determine the flow stresses used within the limit load calculations. Therefore the deterministic concepts assessing the integrity of degraded pipes are available A new post-calculation of the above mentioned tests was performed using probabilistic approaches to assure the component integrity of degraded piping systems. As a result the calculated probability of failure was compared to experimental behaviour during the pipe test. Different reliability techniques were used for the verification of the probabilistic approaches. (author)

  12. Assessment of short through-wall circumferential cracks in pipes. Experiments and analysis: March 1990--December 1994

    Energy Technology Data Exchange (ETDEWEB)

    Brust, F.W.; Scott, P.; Rahman, S. [Battelle, Columbus, OH (United States)] [and others

    1995-04-01

    This topical report summarizes the work performed for the Nuclear Regulatory Commission`s (NRC) research program entitled ``Short Cracks in Piping and Piping Welds`` that specifically focuses on pipes with short through-wall cracks. Previous NRC efforts, conducted under the Degraded Piping Program, focused on understanding the fracture behavior of larger cracks in piping and fundamental fracture mechanics developments necessary for this technology. This report gives details on: (1) material property determinations, (2) pipe fracture experiments, and (3) development, modification, and validation of fracture analysis methods. The material property data required to analyze the experimental results are included. These data were also implemented into the NRC`s PIFRAC database. Three pipe experiments with short through-wall cracks were conducted on large diameter pipe. Also, experiments were conducted on a large-diameter uncracked pipe and a pipe with a moderate-size through-wall crack. The analysis results reported here focus on simple predictive methods based on the J-Tearing theory as well as limit-load and ASME Section 11 analyses. Some of these methods were improved for short-crack-length predictions. The accuracy of the various methods was determined by comparisons with experimental results from this and other programs. 69 refs., 124 figs, 49 tabs.

  13. Assessment of short through-wall circumferential cracks in pipes. Experiments and analysis: March 1990--December 1994

    International Nuclear Information System (INIS)

    Brust, F.W.; Scott, P.; Rahman, S.

    1995-04-01

    This topical report summarizes the work performed for the Nuclear Regulatory Commission's (NRC) research program entitled ''Short Cracks in Piping and Piping Welds'' that specifically focuses on pipes with short through-wall cracks. Previous NRC efforts, conducted under the Degraded Piping Program, focused on understanding the fracture behavior of larger cracks in piping and fundamental fracture mechanics developments necessary for this technology. This report gives details on: (1) material property determinations, (2) pipe fracture experiments, and (3) development, modification, and validation of fracture analysis methods. The material property data required to analyze the experimental results are included. These data were also implemented into the NRC's PIFRAC database. Three pipe experiments with short through-wall cracks were conducted on large diameter pipe. Also, experiments were conducted on a large-diameter uncracked pipe and a pipe with a moderate-size through-wall crack. The analysis results reported here focus on simple predictive methods based on the J-Tearing theory as well as limit-load and ASME Section 11 analyses. Some of these methods were improved for short-crack-length predictions. The accuracy of the various methods was determined by comparisons with experimental results from this and other programs. 69 refs., 124 figs, 49 tabs

  14. Efficiency of defect specific maintenance od steam generator tubes: the case of ODSCC

    International Nuclear Information System (INIS)

    Cizelj, L.; Dvorsek, T.

    1996-01-01

    The outside diameter stress corrosion cracking at tube support plates became the dominating ageing mechanism in steam generators tubes made of Inconel 600. A variety of maintenance approaches were developed and implemented worldwide to deal with this mechanism. Despite different philosophical and physical backgrounds implemented, all of the applied approaches satisfy the relevant regulatory requirements. For our purpose, the maintenance approach consist of: (1) inspection of tubes, (2) accepting or rejecting the defective tube and (3) plugging of rejected tubes. The problem of selecting an optimal maintenance approach is raised in the paper. Consequently, a method comparing the efficiency of applicable maintenance approaches is proposed. The efficiency is defined by three parameters: (a) number of plugged tubes, (b) probability of steam generator tube rupture and (c) predicted accidental leak rates through the defects. An original probabilistic model is proposed to quantify the probability of tube rupture, while procedures available in literature were used to define the accidental leak rates. The numerical example considers the data from Krsko NPP (Westinghouse 632 MWe). The maintenance approaches analyzed include: (i) no repair at all, (ii) traditional defect depth (40%) based maintenance, (iii) alternate plugging criterion (bobbin coil voltage as defined by EPRI and U.S. NRC) and (iv) combined traditional and alternate approach. Advantages of the defect specific approaches (iii) and (iv) over the traditional one (defect depth) are clearly shown. A brief discussion on the optimization of safe life of steam generator is given. (author)

  15. Degradable polyphosphazene/poly(alpha-hydroxyester) blends: degradation studies.

    Science.gov (United States)

    Ambrosio, Archel M A; Allcock, Harry R; Katti, Dhirendra S; Laurencin, Cato T

    2002-04-01

    Biomaterials based on the polymers of lactic acid and glycolic acid and their copolymers are used or studied extensively as implantable devices for drug delivery, tissue engineering and other biomedical applications. Although these polymers have shown good biocompatibility, concerns have been raised regarding their acidic degradation products, which have important implications for long-term implantable systems. Therefore, we have designed a novel biodegradable polyphosphazene/poly(alpha-hydroxyester) blend whose degradation products are less acidic than those of the poly(alpha-hydroxyester) alone. In this study, the degradation characteristics of a blend of poly(lactide-co-glycolide) (50:50 PLAGA) and poly[(50% ethyl glycinato)(50% p-methylphenoxy) phosphazene] (PPHOS-EG50) were qualitatively and quantitatively determined with comparisons made to the parent polymers. Circular matrices (14mm diameter) of the PLAGA, PPHOS-EG50 and PLAGA-PPHOS-EG50 blend were degraded in non-buffered solutions (pH 7.4). The degraded polymers were characterized for percentage mass loss and molecular weight and the degradation medium was characterized for acid released in non-buffered solutions. The amounts of neutralizing base necessary to bring about neutral pH were measured for each polymer or polymer blend during degradation. The poly(phosphazene)/poly(lactide-co-glycolide) blend required significantly less neutralizing base in order to bring about neutral solution pH during the degradation period studied. The results indicated that the blend degraded at a rate intermediate to that of the parent polymers and that the degradation products of the polyphosphazene neutralized the acidic degradation products of PLAGA. Thus, results from these in vitro degradation studies suggest that the PLAGA-PPHOS-EG50 blend may provide a viable improvement to biomaterials based on acid-releasing organic polymers.

  16. Radiation degradation of cellulose

    International Nuclear Information System (INIS)

    Leonhardt, J.W.; Arnold, G.; Baer, M.; Gey, M.; Hubert, S.; Langguth, H.

    1984-01-01

    The application of straw and other cellulose polymers as feedstuff for ruminants is limited by its low digestibility. During recent decades it was attempted to increase the digestibility of straw by several chemical and physical methods. In this work some results of the degradation of gamma and electron treated wheat straw are reported. Complex methods of treatment (e.g. radiation influence and influence of lyes) are taken into consideration. In vitro-experiments with radiation treated straw show that the digestibility can be increased from 20% up to about 80%. A high pressure liquid chromatography method was used to analyze the hydrolysates. The contents of certain species of carbohydrates in the hydrolysates in dependence on the applied dose are given

  17. Exploring bacterial lignin degradation.

    Science.gov (United States)

    Brown, Margaret E; Chang, Michelle C Y

    2014-04-01

    Plant biomass represents a renewable carbon feedstock that could potentially be used to replace a significant level of petroleum-derived chemicals. One major challenge in its utilization is that the majority of this carbon is trapped in the recalcitrant structural polymers of the plant cell wall. Deconstruction of lignin is a key step in the processing of biomass to useful monomers but remains challenging. Microbial systems can provide molecular information on lignin depolymerization as they have evolved to break lignin down using metalloenzyme-dependent radical pathways. Both fungi and bacteria have been observed to metabolize lignin; however, their differential reactivity with this substrate indicates that they may utilize different chemical strategies for its breakdown. This review will discuss recent advances in studying bacterial lignin degradation as an approach to exploring greater diversity in the environment. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Soil degradation in Pakistan

    International Nuclear Information System (INIS)

    Khan, M.R.

    2005-01-01

    This paper diagnoses the issues involved behind the current state, usage, interactions and linkages in the soils in Pakistan. The condition of soils is deteriorating due to developmental and environmental factors such as soil degradation, water pollution, fauna degeneration etc. Issues, problems and constraints faced in the management and usage of soils are diagnosed at different levels in the ecosystems predominant in Pakistan. The research questions propose effective solutions, types of instruments, methods or processes to resolve the issues within the various areas or ecosystems in the most sustainable and effective manner [23]. Biological solutions and methods can be applied at the sub-system level by private individuals or communities at a lower cost, and at a more localized level than engineering methods. Engineering methods may be suited for interventions at a system level rather than at a sub-system level; but even at this level they will be complementary with biological methods. (author)

  19. Degraded Crater Rim

    Science.gov (United States)

    2002-01-01

    (Released 3 May 2002) The Science The eastern rim of this unnamed crater in Southern Arabia Terra is very degraded (beaten up). This indicates that this crater is very ancient and has been subjected to erosion and subsequent bombardment from other impactors such as asteroids and comets. One of these later (younger) craters is seen in the upper right of this image superimposed upon the older crater rim material. Note that this smaller younger crater rim is sharper and more intact than the older crater rim. This region is also mantled with a blanket of dust. This dust mantle causes the underlying topography to take on a more subdued appearance. The Story When you think of Arabia, you probably think of hot deserts and a lot of profitable oil reserves. On Mars, however, Southern Arabia Terra is a cold place of cratered terrain. This almost frothy-looking image is the badly battered edge of an ancient crater, which has suffered both erosion and bombardment from asteroids, comets, or other impacting bodies over the long course of its existence. A blanket of dust has also settled over the region, which gives the otherwise rugged landscape a soft and more subdued appearance. The small, round crater (upper left) seems almost gemlike in its setting against the larger crater ring. But this companionship is no easy romance. Whatever formed the small crater clearly whammed into the larger crater rim at some point, obliterating part of its edge. You can tell the small crater was formed after the first and more devastating impact, because it is laid over the other larger crater. How much younger is the small one? Well, its rim is also much sharper and more intact, which gives a sense that it is probably far more youthful than the very degraded, ancient crater.

  20. Ordered bulk degradation via autophagy

    DEFF Research Database (Denmark)

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

    2008-01-01

    During amino acid starvation, cells undergo macroautophagy which is regarded as an unspecific bulk degradation process. Lately, more and more organelle-specific autophagy subtypes such as reticulophagy, mitophagy and ribophagy have been described and it could be shown, depending on the experimental...... 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...

  1. Degradation of thiram in soil

    International Nuclear Information System (INIS)

    Raghu, K.; Murthy, N.B.K.; Kumarsamy, R.

    1975-01-01

    Determination of the residual 35 S labelled tetramethylthiuram disulfide showed that the fungicide persisted longer in sterilized than in unsterilized soil, while the chloroform extractable radioactivity decreased, the water extractable radioactivity increased with increase in time. However, in sterilized soil the water extractable radioactivity remained more or less constant. Degradation of the fungicide was further demonstrated by the release of C 35 S 2 from soil treated with labelled thiram. Dimethylamine was found to be one of the degradation products. A bacterium isolated from thiram-enriched soil could degrade the fungicide in shake culture. The degradation pathways of thiram in sterilized and unsterilized soils are discussed. (author)

  2. In vitro degradation of ribosomes.

    Science.gov (United States)

    Mora, G; Rivas, A

    1976-12-01

    The cytoplasmic ribosomes from Euglena gracilis var. bacillaris are found to be of two types taking into consideration their stability "in vitro". In the group of unstable ribosomes the large subunit is degraded. The other group apparently does not suffer any degradation under the conditions described. However the RNAs extracted from both types of ribosomes are degraded during sucrose density gradients. The degradation of the largest RNA species has been reported previously, but no comment has been made about the stability of the ribosome itself.

  3. The radiation degradation of polypropylene

    International Nuclear Information System (INIS)

    De Hollain, G.

    1977-04-01

    Polypropylene is used extensively in the manufacture of disposable medical devices because of its superior properties. Unfortunately this polymer does not lend itself well to radiation sterilization, undergoing serious degradation which affects the mechanical properties of the polymer. In this paper the effects of radiation on the mechanical and physical properties of polypropylene are discussed. A programme of research to minimize the radiation degradation of this polymer through the addition of crosslinking agents to counteract the radiation degradation is proposed. It is furthermore proposed that a process of annealing of the irradiated polymer be investigated in order to minimize the post-irradiation degradation of the polypropylene [af

  4. Circumferential or sectored beam arrangements for stereotactic body radiation therapy (SBRT) of primary lung tumors: Effect on target and normal-structure dose-volume metrics

    Energy Technology Data Exchange (ETDEWEB)

    Rosenberg, Mara W. [Broad Institute of MIT and Harvard, Cambridge, MA (United States); Department of Physics, Brandeis University, Waltham, MA (United States); Kato, Catherine M. [Macalester College, St. Paul, MN (United States); Carson, Kelly M.P. [The University of North Carolina, Chapel Hill, NC (United States); Matsunaga, Nathan M. [Santa Clara University, Santa Clara, CA (United States); Arao, Robert F. [Department of Public Health and Preventive Medicine, Oregon Health and Science University, Portland, OR (United States); Doss, Emily J. [Department of Internal Medicine, Providence St. Vincent Medical Center, Portland, OR (United States); McCracken, Charles L. [Department of Radiation Medicine, Oregon Health and Science University, Portland, OR (United States); Meng, Lu Z. [Department of Radiation Oncology, University of California Davis Comprehensive Cancer Center, Sacramento, CA (United States); Chen, Yiyi [Department of Public Health and Preventive Medicine, Oregon Health and Science University, Portland, OR (United States); Laub, Wolfram U.; Fuss, Martin [Department of Radiation Medicine, Oregon Health and Science University, Portland, OR (United States); Department of Nuclear Engineering and Radiation Health Physics, Oregon State University, Corvallis, OR (United States); Tanyi, James A., E-mail: tanyij@ohsu.edu [Department of Radiation Medicine, Oregon Health and Science University, Portland, OR (United States); Department of Nuclear Engineering and Radiation Health Physics, Oregon State University, Corvallis, OR (United States)

    2013-01-01

    To compare 2 beam arrangements, sectored (beam entry over ipsilateral hemithorax) vs circumferential (beam entry over both ipsilateral and contralateral lungs), for static-gantry intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) delivery techniques with respect to target and organs-at-risk (OAR) dose-volume metrics, as well as treatment delivery efficiency. Data from 60 consecutive patients treated using stereotactic body radiation therapy (SBRT) for primary non–small-cell lung cancer (NSCLC) formed the basis of this study. Four treatment plans were generated per data set: IMRT/VMAT plans using sectored (-s) and circumferential (-c) configurations. The prescribed dose (PD) was 60 Gy in 5 fractions to 95% of the planning target volume (PTV) (maximum PTV dose ∼ 150% PD) for a 6-MV photon beam. Plan conformality, R{sub 50} (ratio of volume circumscribed by the 50% isodose line and the PTV), and D{sub 2} {sub cm} (D{sub max} at a distance ≥2 cm beyond the PTV) were evaluated. For lungs, mean doses (mean lung dose [MLD]) and percent V{sub 30}/V{sub 20}/V{sub 10}/V{sub 5} Gy were assessed. Spinal cord and esophagus D{sub max} and D{sub 5}/D{sub 50} were computed. Chest wall (CW) D{sub max} and absolute V{sub 30}/V{sub 20}/V{sub 10}/V{sub 5} {sub Gy} were reported. Sectored SBRT planning resulted in significant decrease in contralateral MLD and V{sub 10}/V{sub 5} {sub Gy}, as well as contralateral CW D{sub max} and V{sub 10}/V{sub 5} {sub Gy} (all p < 0.001). Nominal reductions of D{sub max} and D{sub 5}/D{sub 50} for the spinal cord with sectored planning did not reach statistical significance for static-gantry IMRT, although VMAT metrics did show a statistically significant decrease (all p < 0.001). The respective measures for esophageal doses were significantly lower with sectored planning (p < 0.001). Despite comparable dose conformality, irrespective of planning configuration, R{sub 50} significantly improved with IMRT

  5. Limitations and ceiling effects with circumferential minimally invasive correction techniques for adult scoliosis: analysis of radiological outcomes over a 7-year experience.

    Science.gov (United States)

    Anand, Neel; Baron, Eli M; Khandehroo, Babak

    2014-05-01

    Minimally invasive correction of adult scoliosis is a surgical method increasing in popularity. Limited data exist, however, as to how effective these methodologies are in achieving coronal plane and sagittal plane correction in addition to improving spinopelvic parameters. This study serves to quantify how much correction is possible with present circumferential minimally invasive surgical (cMIS) methods. Ninety patients were selected from a database of 187 patients who underwent cMIS scoliosis correction. All patients had a Cobb angle greater than 15°, 3 or more levels fused, and availability of preoperative and postoperative 36-inch standing radiographs. The mean duration of follow-up was 37 months. Preoperative and postoperative Cobb angle, sagittal vertical axis (SVA), coronal balance, lumbar lordosis (LL), and pelvic incidence (PI) were measured. Scatter plots were performed comparing the pre- and postoperative radiological parameters to calculate ceiling effects for SVA correction, Cobb angle correction, and PI-LL mismatch correction. The mean preoperative SVA value was 60 mm (range 11.5-151 mm); the mean postoperative value was 31 mm (range 0-84 mm). The maximum SVA correction achieved with cMIS techniques in any of the cases was 89 mm. In terms of coronal Cobb angle, a mean correction of 61% was noted, with a mean preoperative value of 35.8° (range 15°-74.7°) and a mean postoperative value of 13.9° (range 0°-32.5°). A ceiling effect for Cobb angle correction was noted at 42°. The ability to correct the PI-LL mismatch to 10° was limited to cases in which the preoperative PI-LL mismatch was 38° or less. Circumferential MIS techniques as currently used for the treatment of adult scoliosis have limitations in terms of their ability to achieve SVA correction and lumbar lordosis. When the preoperative SVA is greater than 100 mm and a substantial amount of lumbar lordosis is needed, as determined by spinopelvic parameter calculations, surgeons should

  6. Predictors of chronic pulmonary vein reconnections after contact force-guided ablation: importance of completing electrical isolation with circumferential lines and creating sufficient ablation lesion densities.

    Science.gov (United States)

    Nakamura, Kohki; Naito, Shigeto; Sasaki, Takehito; Minami, Kentaro; Take, Yutaka; Shimizu, Satoru; Yamaguchi, Yoshiaki; Yano, Toshiaki; Senga, Michiharu; Yamashita, Eiji; Sugai, Yoshinao; Kumagai, Koji; Funabashi, Nobusada; Oshima, Shigeru

    2016-12-01

    We aimed to identify the predictors of chronic pulmonary vein reconnections (CPVRs) after contact force (CF)-guided circumferential PV isolation (CPVI) of atrial fibrillation (AF). Forty-nine consecutive patients undergoing second ablation procedures for recurrent AF after CF-guided ablation were retrospectively studied. The CPVI was performed by point-by-point ablation with a target CF of 15-20 g. The incidence of CPVRs was evaluated along the right- and left-sided anterior and posterior CPVI regions (Ant-RPVs, Post-RPVs, Ant-LPVs, and Post-LPVs). CPVRs were observed in 30.6, 22.4, 20.4, and 32.7 % of patients along the Ant-RPVs, Post-RPVs, Ant-LPVs, and Post-LPVs, respectively (P = 0.436). In the multivariate logistic analyses, completing a left atrium-PV conduction block with touch-up ablation inside the initially estimated CPVI lines (Ant-RPVs, Post-RPVs, Ant-LPVs, Post-LPVs; odds ratio [OR] 5.747, 15.000, 207.619, 7.940; P = 0.032, 0.004, 0.034, 0.021) and region length (Post-LPVs; OR 3.183, P = 0.027) were positive predictors of CPVRs, while the mean CF (Ant-RPVs; OR 0.861, P = 0.045) and number of radiofrequency applications per unit length (Ant-LPVs, Post-LPVs; OR 0.038, 0.122; P = 0.034, 0.029) were negative predictors. At optimal cutoffs of 5.8 cm for the region length, 14.2 g for the mean CF, and 1.97/cm (Ant-LPVs) and 2.01/cm (Post-LPVs) for the radiofrequency application density, the sensitivity and specificity were 93.8 and 63.6 %, 60.0 and 76.5 %, 90.0 and 64.1 %, and 75.0 and 63.6 %, respectively. Completing PVI with circumferential lines without touch-up ablation and creating a sufficient density of radiofrequency ablation lesions on the lines with a sufficient CF may be necessary to prevent CPVRs after a CF-guided CPVI.

  7. Polycarbonate radiolytic degradation and stabilization

    International Nuclear Information System (INIS)

    Araujo, E.S. de

    1994-01-01

    Polycarbonate Durolon, useful for medical supplies fabrication, is submitted to gamma radiation for sterilization purposes. Scissions in main chain occur, in carbonyl groups, producing molecular degradations and yellowness. The radiolytic stabilization is obtained through additive to the polymer. In this work some degradation and stabilization aspects are presented. (L.C.J.A.). 7 refs, 7 figs, 2 tabs

  8. Degradation of copepod fecal pellets

    DEFF Research Database (Denmark)

    Poulsen, Louise K.; Iversen, Morten

    2008-01-01

    amount of fecal pellets. The total degradation rate of pellets by the natural plankton community of Oresund followed the phytoplankton biomass, with maximum degradation rate during the spring bloom (2.5 +/- 0.49 d(-1)) and minimum (0.52 +/- 0.14 d(-1)) during late winter. Total pellet removal rate ranged...

  9. Degradable polymers for tissue engineering

    NARCIS (Netherlands)

    van Dijkhuizen-Radersma, Riemke; Moroni, Lorenzo; van Apeldoorn, Aart A.; Zhang, Zheng; Grijpma, Dirk W.; van Blitterswijk, Clemens A.

    2008-01-01

    This chapter elaborates the degradable polymers for tissue engineering and their required scaffold material in tissue engineering. It recognizes the examples of degradable polymers broadly used in tissue engineering. Tissue engineering is the persuasion of the body to heal itself through the

  10. MOSFET Degradation Under RF Stress

    NARCIS (Netherlands)

    Sasse, G.T.; Kuper, F.G.; Schmitz, Jurriaan

    2008-01-01

    We report on the degradation of MOS transistors under RF stress. Hot-carrier degradation, negative-bias temperature instability, and gate dielectric breakdown are investigated. The findings are compared to established voltage- and field-driven models. The experimental results indicate that the

  11. Designs for degraded Trbovlje

    Directory of Open Access Journals (Sweden)

    Naja Marot

    2005-01-01

    Full Text Available As an introduction, two degraded urban areas are presented. The first, planning unit seven, is situated in the southeastern part of Trbovlje town. The other, called Speke, lies to the south of Liverpool. The basis for the concept and context of urban renewal model are given by comparison between the newest Slovene and British spatial planning legislation, analyses of the Design management plan Nasipi and Supplementary Planning Document Edge Lane West, and review of different approaches to local communities’ involvement. Based on all the thus far collected data, a questionnaire about quality of living, knowledge of planning system and area perception was produced. Initially, it was used in a pilot residential area Žabjek, and afterwards, a shortened version was carried out in units lying in other parts of the town. Other stakeholders also expressed their ideas about how to develop planning unit seven. Speke Garston as another example of successful urban renewal is given. In conclusion guidelines for method and context development of urban renewal are given for planning unit seven, with emphasis on the Žabjek estate.

  12. Lysosomal degradation of membrane lipids.

    Science.gov (United States)

    Kolter, Thomas; Sandhoff, Konrad

    2010-05-03

    The constitutive degradation of membrane components takes place in the acidic compartments of a cell, the endosomes and lysosomes. Sites of lipid degradation are intralysosomal membranes that are formed in endosomes, where the lipid composition is adjusted for degradation. Cholesterol is sorted out of the inner membranes, their content in bis(monoacylglycero)phosphate increases, and, most likely, sphingomyelin is degraded to ceramide. Together with endosomal and lysosomal lipid-binding proteins, the Niemann-Pick disease, type C2-protein, the GM2-activator, and the saposins sap-A, -B, -C, and -D, a suitable membrane lipid composition is required for degradation of complex lipids by hydrolytic enzymes. Copyright 2009 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  13. Generation of plastic influence functions for J-integral and crack opening displacement of thin-walled pipes with a short circumferential through-wall crack

    International Nuclear Information System (INIS)

    Park, Jeong Soon; Choi, Young Hwan; Im, Seyoung

    2014-01-01

    Fracture mechanics parameters such as the J-integral and crack opening displacement (COD), are necessary for Leak-Before-Break (LBB) evaluation. The famous two estimation methods, the GE/EPRI and the Reference Stress Method (RSM), have their applicability limit with regard to the ratio of a pipe mean radius to thickness (R m /t). In order to extend their applicability limit to a thin walled pipe, several finite element analyses are performed for the J-integral and COD, and then new plastic influence functions are developed for thin-walled pipes with a short circumferential through-wall crack. With the newly generated plastic influence functions, the GE/EPRI and the RSM give closer results with those obtained from detailed finite element analyses. In addition, C*-integral and COD rate are estimated by using the new plastic influence functions and they are well matched with elastic–creep finite element analysis results under the power-law creep condition. Since the LBB concept can be applied to a piping system in a Korean Sodium-cooled Fast Reactor (SFR) which is designed to have thin-walled pipes and to operate in high temperature enough to cause creep, this paper can be applied for the LBB assessment of thin-walled pipes with a short through-wall crack in the SFR

  14. Prediction of fracture parameters of circumferential through-wall cracks in the interface between an elbow and a pipe under internal pressure

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Youn Young; Huh, Nam Su [Dept. of Mechanical System Design Engineering, Seoul National Univ. of Science and Technology, Seoul (Korea, Republic of); Jeong, Jae Uk [Doosan Heavy Industries and Construction, Changwon (Korea, Republic of)

    2016-09-15

    This paper provides plastic influence functions of GE/EPRI method for calculating J and Crack opening displacement (COD) of pipes with a circumferential Through-wall crack (TWC) in the interface between an elbow and a straight pipe by using 3-dimensional (3-D) elastic-plastic finite element analyses for Ramberg-Osgood (R-O) materials, in which internal pressure was considered as a loading condition. The proposed plastic influence functions are tabulated as a function of the pipe geometries, crack length and strain hardening exponent. In order to provide sufficient confidence for the proposed plastic influence functions, the estimation scheme using the proposed plastic influence functions for J and COD of cracked elbows was validated against FE results using R-O parameters for the SA312 TP316 stainless steel. Moreover, the predicted J and COD for elbows with a TWC in the interface between an elbow and a pipe by the proposed scheme were compared with those for cracked straight pipes to investigate the effect of the elbow geometries on crack behavior of elbows. One important point is that crack behaviors in the interface between an elbow and a straight pipe can be significantly different with those in straight pipes according to pipe thickness, crack length and bend radius of elbows. Thus, the proposed plastic influence functions can be useful to predict accurate J and COD for cracked elbows.

  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. Prognostic significance of cancer within 1 mm of the circumferential resection margin in oesophageal cancer patients following neo-adjuvant chemotherapy.

    Science.gov (United States)

    Salih, Tamir; Jose, Paul; Mehta, Samir P; Mirza, Ahmed; Udall, Gavin; Pritchard, Susan A; Hayden, Jeremy D; Grabsch, Heike I

    2013-03-01

    The prognostic significance of the circumferential resection margin (CRM) status in oesophageal cancer patients treated with neo-adjuvant chemotherapy and radical resection is controversial. Furthermore, it is currently unclear whether patients with cancer located at the CRM have a prognosis different from that of those with cancer within 1 mm of the CRM. This is the first study aiming to establish the optimal tumour-free distance from the CRM of an oesophagectomy in patients who have undergone neo-adjuvant chemotherapy. The clinicopathological data of 232 oesophageal cancer patients from two UK centres were analysed. The CRM status was classified as Group A (cancer at the CRM), Group B (cancer within 1 mm but not at the CRM) and Group C (no cancer within 1 mm from the CRM). The relationship between the CRM status and patient survival was investigated. Thirty-eight specimens were classified as Group A, 89 as Group B and 105 as Group C. CRM status was related to the depth of tumour invasion (P CRM or within 1 mm of the CRM of the resected specimen have a significantly worse survival than patients with no cancer cells within 1 mm of the margin. However, this study suggests that the overall prognostic significance of the CRM status is limited in this cohort and the postoperative lymph node status is the most important prognostic factor in oesophageal cancer patients treated with neo-adjuvant chemotherapy and surgery.

  17. 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

    2016-04-01

    The circumferential resection margin (CRM) is a key prognostic factor after rectal cancer resection. We sought to identify factors associated with CRM involvement (CRM+). 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 CRM+. Of 23,464 eligible 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. 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. Copyright © 2016 IJS Publishing Group Limited. Published by Elsevier Ltd. All rights reserved.

  18. Is circumferential urethral mobilisation an overdo? A prospective outcome analysis of dorsal onlay and dorso - lateral onlay BMGU for anterior urethral strictures.

    Science.gov (United States)

    Prakash, Gaurav; Singh, Bhupendra Pal; Sinha, Rahul Janak; Jhanwar, Ankur; Sankhwar, Satyanarayan

    2018-01-01

    For dorsal onlay graft placement, unilateral urethral mobilization is less invasive than standard circumferential urethral mobilization. Apart from success in terms of patency of urethra, other issues like sexual function, overall quality of life and patient satisfaction remain important issues while comparing outcomes of urethroplasty. To prospectively compare the objective as well as subjective outcomes of two approaches. Between July 2011 and January 2015, 136 adult males having anterior urethral stricture with urethral lumen ≥ 6 Fr. were prospectively assigned between two groups by alternate randomization. Operative time, complications, success rate (no obstructive symptoms, no need of any postoperative intervention, Q max > 15mL/sec), sexual functions (using Brief Male Sexual Function Inventory) were compared. Baseline parameters were similar in both groups (68 in each group). Overall success rate was similar in both groups (89 % and 91 % respectively). Improvement in total LUTS scores was similar in groups. Changes in overall health status (VAS and EQ 5D) was equal in both groups. Erectile function score was significantly decreased in DO than DL group while ejaculatory function and sexual desire remained stable after urethroplasty in both groups. In anterior urethral stricture buccal mucosa graft provides satisfactory results as onlay technique. No technique whether dorsolateral and dorsal techniques is superior to other. Dorsolateral technique needs minimal urethral mobilization and should be preferred whenever feasible. Copyright® by the International Brazilian Journal of Urology.

  19. Prediction of fracture parameters of circumferential through-wall cracks in the interface between an elbow and a pipe under internal pressure

    International Nuclear Information System (INIS)

    Jang, Youn Young; Huh, Nam Su; Jeong, Jae Uk

    2016-01-01

    This paper provides plastic influence functions of GE/EPRI method for calculating J and Crack opening displacement (COD) of pipes with a circumferential Through-wall crack (TWC) in the interface between an elbow and a straight pipe by using 3-dimensional (3-D) elastic-plastic finite element analyses for Ramberg-Osgood (R-O) materials, in which internal pressure was considered as a loading condition. The proposed plastic influence functions are tabulated as a function of the pipe geometries, crack length and strain hardening exponent. In order to provide sufficient confidence for the proposed plastic influence functions, the estimation scheme using the proposed plastic influence functions for J and COD of cracked elbows was validated against FE results using R-O parameters for the SA312 TP316 stainless steel. Moreover, the predicted J and COD for elbows with a TWC in the interface between an elbow and a pipe by the proposed scheme were compared with those for cracked straight pipes to investigate the effect of the elbow geometries on crack behavior of elbows. One important point is that crack behaviors in the interface between an elbow and a straight pipe can be significantly different with those in straight pipes according to pipe thickness, crack length and bend radius of elbows. Thus, the proposed plastic influence functions can be useful to predict accurate J and COD for cracked elbows

  20. Improvement of C*-integral and Crack Opening Displacement Estimation Equations for Thin-walled Pipes with Circumferential Through-wall Cracks

    International Nuclear Information System (INIS)

    Park, Jeong Soon; Jhung, Myung Jo

    2012-01-01

    Since the LBB(Leak-Before-Break) concept has been widely applied to high energy piping systems in the pressurized water reactors, a number of engineering estimation methods had been developed for J-integral and COD values. However, those estimation methods were mostly reliable for relatively thick-walled pipes about R m /t=5 or 10. As the LBB concept might be considered in the design stage of the SFR (Sodium-cooled Fast Reactor) which has relatively thin-walled pipes due to its low design pressure, the applicability of current estimation methods should be investigated for thin-walled pipes. Along with the J-integral and COD, the estimation method for creep fracture mechanics parameters, C*- integral and COD rate, is required because operating temperature of SFR is high enough to induce creep in the structural materials. In this study, the applicability of the current C*- integral and COD estimation methods to thin-walled pipes is studied for a circumferential through-wall crack using the finite element (FE) method. Based on the FE results, enhancement of the current estimation methods is made

  1. Intrafamiliar clinical variability of circumferential skin creases Kunze type caused by a novel heterozygous mutation of N-terminal TUBB gene.

    Science.gov (United States)

    Dentici, M L; Terracciano, A; Bellacchio, E; Capolino, R; Novelli, A; Digilio, M C; Dallapiccola, B

    2018-02-10

    Circumferential skin creases Kunze type (CSC-KT; OMIM 156610, 616734) is a rare disorder characterized by folding of excess skin, which leads to ringed creases, known as Michelin Tire Baby Syndrome (MTBS). CSC-KT patients also exhibit facial dysmorphism, growth retardation, intellectual disability (ID) and multiple congenital malformations. Recently, 2 heterozygous mutations in TUBB gene and 4 mutations (both homozygous and heterozygous) in MAPRE2 gene were identified in 3 and 4 CSC-KT patients, respectively. In the 3 TUBB gene-related CSC-KT patients, all mutations fall in the N-terminal gene domain and were de novo. Mutations in the C-terminal of TUBB gene have been associated to microcephaly and structural brain malformation, in the absence of CSC-KT features. We report a 9-year-old boy with a diagnosis of CSC-KT based on MTBS, facial dysmorphism, microcephaly, severe ID, cortical atrophy and corpus callosum hypoplasia. Sanger sequencing identified a novel heterozygous c.218T>C (p.Met73Thr) mutation in the N-terminal of TUBB gene, that was inherited from the mother affected by isolated MTBS. This is the first report of inherited TUBB gene-related CSC-KT resulting from a novel heterozygous mutation in the N-terminal domain. Present data support the role of TUBB mutations in CSC-KT and definitely includes CSC-KT syndrome within the tubulinopathies. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

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

    International Nuclear Information System (INIS)

    Lee, Seung Chan; Kim, Chang Won; Jeon, Ung Bae

    2016-01-01

    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

  3. 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.

  4. Drift Degradation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Dwayne C. Kicker

    2001-09-28

    A statistical description of the probable block sizes formed by fractures around the emplacement drifts has been developed for each of the lithologic units of the repository host horizon. A range of drift orientations with the drift azimuth varied in 15{sup o} increments has been considered in the static analysis. For the quasi-static seismic analysis, and the time-dependent and thermal effects analysis, two drift orientations have been considered: a drift azimuth of 105{sup o} and the current emplacement drift azimuth of 75{sup o}. The change in drift profile resulting from progressive deterioration of the emplacement drifts has been assessed both with and without backfill. Drift profiles have been determined for four different time increments, including static (i.e., upon excavation), 200 years, 2,000 years, and 10,000 years. The effect of seismic events on rock fall has been analyzed. Block size distributions and drift profiles have been determined for three seismic levels, including a 1,000-year event, a 5,000-year event, and a 10,000-year event. Data developed in this modeling and analysis activity have been entered into the TDMS (DTN: MO0109RDDAAMRR.003). The following conclusions have resulted from this drift degradation analysis: (1) The available fracture data are suitable for supporting a detailed key block analysis of the repository host horizon rock mass. The available data from the north-south Main Drift and the east-west Cross Drift provide a sufficient representative fracture sample of the repository emplacement drift horizon. However, the Tptpln fracture data are only available from a relatively small section of the Cross Drift, resulting in a smaller fracture sample size compared to the other lithologic units. This results in a lower degree of confidence that the key block data based on the Tptpln data set is actually representative of the overall Tptpln key block population. (2) The seismic effect on the rock fall size distribution for all events

  5. Intrinsic immunogenicity of rapidly-degradable polymers evolves during degradation.

    Science.gov (United States)

    Andorko, James I; Hess, Krystina L; Pineault, Kevin G; Jewell, Christopher M

    2016-03-01

    Recent studies reveal many biomaterial vaccine carriers are able to activate immunostimulatory pathways, even in the absence of other immune signals. How the changing properties of polymers during biodegradation impact this intrinsic immunogenicity is not well studied, yet this information could contribute to rational design of degradable vaccine carriers that help direct immune response. We use degradable poly(beta-amino esters) (PBAEs) to explore intrinsic immunogenicity as a function of the degree of polymer degradation and polymer form (e.g., soluble, particles). PBAE particles condensed by electrostatic interaction to mimic a common vaccine approach strongly activate dendritic cells, drive antigen presentation, and enhance T cell proliferation in the presence of antigen. Polymer molecular weight strongly influences these effects, with maximum stimulation at short degradation times--corresponding to high molecular weight--and waning levels as degradation continues. In contrast, free polymer is immunologically inert. In mice, PBAE particles increase the numbers and activation state of cells in lymph nodes. Mechanistic studies reveal that this evolving immunogenicity occurs as the physicochemical properties and concentration of particles change during polymer degradation. This work confirms the immunological profile of degradable, synthetic polymers can evolve over time and creates an opportunity to leverage this feature in new vaccines. Degradable polymers are increasingly important in vaccination, but how the inherent immunogenicity of polymers changes during degradation is poorly understood. Using common rapidly-degradable vaccine carriers, we show that the activation of immune cells--even in the absence of other adjuvants--depends on polymer form (e.g., free, particulate) and the extent of degradation. These changing characteristics alter the physicochemical properties (e.g., charge, size, molecular weight) of polymer particles, driving changes in

  6. Operationalizing measurement of forest degradation

    DEFF Research Database (Denmark)

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

    2015-01-01

    . In Tanzania, charcoal production is considered a major cause of forest degradation, but is challenging to quantify due to sub-canopy biomass loss, remote production sites and illegal trade. We studied two charcoal production sites in dry Miombo woodland representing open woodland conditions near human......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...

  7. 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.

  8. Ecosystemic approaches to land degradation

    International Nuclear Information System (INIS)

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

    2009-01-01

    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.

  9. 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....

  10. Predicting degradability of organic chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Finizio, A; Vighi, M [Milan Univ. (Italy). Ist. di Entomologia Agraria

    1992-05-01

    Degradability, particularly biodegradability, is one of the most important factors governing the persistence of pollutants in the environment and consequently influencing their behavior and toxicity in aquatic and terrestrial ecosystems. The need for reliable persistence data in order to assess the environmental fate and hazard of chemicals by means of predictive approaches, is evident. Biodegradability tests are requested by the EEC directive on new chemicals. Neverthless, degradation tests are not easy to carry out and data on existing chemicals are very scarce. Therefore, assessing the fate of chemicals in the environment from the simple study of their structure would be a useful tool. Rates of degradation are a function of the rates of a series of processes. Correlation between degradation rates and structural parameters are will be facilitated if one of the processes is rate determining. This review is a survey of studies dealing with relationships between structure and biodegradation of organic chemicals, to identify the value and limitations of this approach.

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

    Science.gov (United States)

    Barret, Maximilien; Batteux, Frédéric; Beuvon, Frédéric; Mangialavori, Luigi; Chryssostalis, Ariane; Pratico, Carlos; Chaussade, Stanislas; Prat, Frédéric

    2012-05-28

    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. 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. 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. 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.

  12. Control chart analysis of data regarding 0.2% yield strength (YS) and percent total circumferential elongation (%TCE) for zircaloy clad tubes for PHWR and BWR fuels

    International Nuclear Information System (INIS)

    Yadav, M.B.; Singh, Hari; Vaidyanathan, S.; Sood, D.D.; Raghavan, S.V.; Bandyopadhyay, A.K.; Kulkarni, P.G.

    1992-01-01

    Zircaloy cladding tubes for PHWR and BWR fuels are manufactured and tested at Nuclear Fuel Complex (NFC), Hyderabad. Atomic Fuels Division is carrying out the quality assurance of the fuels on behalf of Nuclear Power Corporation (NPC). In this paper an attempt has been made to assess whether the quality of the clad tubes has met the requirements specified for the two mechanical properties of the tubes namely 0.2% yield strength and percent total circumferential elongation using control chart technique. For this purpose data for about 100 lots in each case were used. Process means and process standard deviations for these properties and the control limits for the corresponding control charts were estimated. The main findings are: (i) In case of PHWR tubes the production quality level with respect to 0.2% YS is higher, while that in case of %TCE is lower causing rejection of lots. On the other hand in the case of BWR tubes the production quality levels with respect to both the properties are higher than the required one. (ii) With respect to 0.2% YS, in case of BWR tubes a change in the pattern of distribution is detected beyond the lot serial no.47. However in case of PHWR tubes, though the data falls into two groups, no such pattern is seen. A modification in the acceptance/rejection criterion of the lot has been suggested. It is also pointed out that to have a correct picture of the total variation it is necessary to study the within tube variation. (author). 4 figs, 2 tabs

  13. Gonioscopy assisted transluminal trabeculotomy: an ab interno circumferential trabeculotomy for the treatment of primary congenital glaucoma and juvenile open angle glaucoma.

    Science.gov (United States)

    Grover, Davinder S; Smith, Oluwatosin; Fellman, Ronald L; Godfrey, David G; Butler, Michelle R; Montes de Oca, Ildamaris; Feuer, William J

    2015-08-01

    To introduce a novel ab interno 360° trabeculotomy for treating primary congenital glaucoma (PCG) and juvenile open angle glaucoma (JOAG) and report preliminary results. A retrospective chart review of patients who underwent a gonioscopy assisted transluminal trabeculotomy (GATT) procedure by four of the authors (DSG, OS, RLF and DGG) between October 2011 and October 2013. The surgery was performed in patients ≤30 years old with a dysgenic anterior segment angle and uncontrolled PCG and JOAG. Fourteen eyes of 10 patients underwent GATT with follow-up >12 months (12-33 months; mean 20.4). Patients ranged in age from 17 months to 30 years (mean=18.4 years), and five (50%) were female patients. No complications occurred during or following surgery except for early postoperative hyphema in five (36%) of eyes, all cleared by 1 month. The mean intraocular pressure (IOP) decreased from 27.3 to 14.8 mm Hg and the mean number of medications required decreased from 2.6 to 0.86. Five eyes had a drop in IOP ≥15 mm Hg (range 15-39). The preliminary results and safety for GATT, a minimally invasive conjunctival sparing circumferential trabeculotomy, are promising and at least equivalent to previous results for ab externo trabeculotomy for the treatment of PCG and JOAG. All eyes in the study were considered a clinical success. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  14. Intraoperative Radiation Therapy Reduces Local Recurrence Rates in Patients With Microscopically Involved Circumferential Resection Margins After Resection of Locally Advanced Rectal Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Alberda, Wijnand J.; Verhoef, Cornelis [Department of Surgery, Division of Surgical Oncology, Erasmus MC Cancer Institute, Rotterdam (Netherlands); Nuyttens, Joost J. [Department of Radiotherapy, Erasmus MC Cancer Institute, Rotterdam (Netherlands); Meerten, Esther van [Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam (Netherlands); Rothbarth, Joost [Department of Surgery, Division of Surgical Oncology, Erasmus MC Cancer Institute, Rotterdam (Netherlands); Wilt, Johannes H.W. de [Department of Surgery, Division of Surgical Oncology, Radboud University Nijmegen Medical Center, Nijmegen (Netherlands); Burger, Jacobus W.A., E-mail: j.burger@erasmusmc.nl [Department of Surgery, Division of Surgical Oncology, Erasmus MC Cancer Institute, Rotterdam (Netherlands)

    2014-04-01

    Purpose: Intraoperative radiation therapy (IORT) is advocated by some for patients with locally advanced rectal cancer (LARC) who have involved or narrow circumferential resection margins (CRM) after rectal surgery. This study evaluates the potentially beneficial effect of IORT on local control. Methods and Materials: All surgically treated patients with LARC treated in a tertiary referral center between 1996 and 2012 were analyzed retrospectively. The outcome in patients treated with IORT with a clear but narrow CRM (≤2 mm) or a microscopically involved CRM was compared with the outcome in patients who were not treated with IORT. Results: A total of 409 patients underwent resection of LARC, and 95 patients (23%) had a CRM ≤ 2 mm. Four patients were excluded from further analysis because of a macroscopically involved resection margin. In 43 patients with clear but narrow CRMs, there was no difference in the cumulative 5-year local recurrence-free survival of patients treated with (n=21) or without (n=22) IORT (70% vs 79%, P=.63). In 48 patients with a microscopically involved CRM, there was a significant difference in the cumulative 5-year local recurrence-free survival in favor of the patients treated with IORT (n=31) compared with patients treated without IORT (n=17) (84 vs 41%, P=.01). Multivariable analysis confirmed that IORT was independently associated with a decreased local recurrence rate (hazard ratio 0.24, 95% confidence interval 0.07-0.86). There was no significant difference in complication rate of patients treated with or without IORT (65% vs 52%, P=.18) Conclusion: The current study suggests that IORT reduces local recurrence rates in patients with LARC with a microscopically involved CRM.

  15. Can histopathologic assessment of circumferential margin after preoperative pelvic chemoradiotherapy for T3-T4 rectal cancer predict for 3-year disease-free survival?

    International Nuclear Information System (INIS)

    Mawdsley, Suzannah; Glynne-Jones, Rob; Grainger, Juliet; Richman, Paul; Makris, Andreas; Harrison, Mark; Ashford, Richard; Harrison, Richard A.; Osborne, Melanie; Livingstone, Jeremy I.; MacDonald, Peter; Mitchell, Ian C.; Meyrick-Thomas, John; Northover, John; Windsor, Alastair; Novell, Richard; Wallace, Marina

    2005-01-01

    Purpose: This study set out to determine the impact of a positive circumferential resection margin (CRM) (R1-R2) and pathologic downstaging on local recurrence and survival in patients with borderline resectable or unresectable rectal adenocarcinoma treated with neoadjuvant chemoradiotherapy (CRT). Methods and Materials: A total of 150 patients with locally advanced rectal cancer were treated with long-course neoadjuvant CRT using low-dose folinic acid and 5-fluorouracil. CRT was followed 6-12 weeks later by surgical excision. The CRM rate and incidence, site, and pattern of local and systemic recurrences were recorded. The median follow-up was 25 months. Results: The overall median survival was 37 months, with a 5-year overall survival rate of 34%. Of the 150 patients, 122 underwent curative resection; 12% had a complete pathologic response, and downstaging to pT1-T2 occurred in an additional 16%. A negative CRM (R0) was achieved in 65% overall (98 of 150). Local recurrence occurred in 10% of those with R0 resection and 62% of those with R1-R2 resections. Distant metastases occurred in 29% of those with R0 resections and 75% of those with R1-R2 resections. The 3-year disease-free and 3-year overall survival rate was 9% and 25% and 52% and 64%, respectively, for patients with and without a histologically positive CRM. Conclusion: After 5-fluorouracil-based CRT, a positive CRM predicted for a high risk of subsequent local recurrence and a 3-year disease-free survival rate of only 9%. For this reason, the CRM should be considered a major prognostic factor and should be validated in future trials as an early alternative clinical endpoint

  16. Preoperative magnetic resonance imaging assessment of circumferential resection margin predicts disease-free survival and local recurrence: 5-year follow-up results of the MERCURY study.

    Science.gov (United States)

    Taylor, Fiona G M; Quirke, Philip; Heald, Richard J; Moran, Brendan J; Blomqvist, Lennart; Swift, Ian R; Sebag-Montefiore, David; Tekkis, Paris; Brown, Gina

    2014-01-01

    The prognostic relevance of preoperative high-resolution magnetic resonance imaging (MRI) assessment of circumferential resection margin (CRM) involvement is unknown. This follow-up study of 374 patients with rectal cancer reports the relationship between preoperative MRI assessment of CRM staging, American Joint Committee on Cancer (AJCC) TNM stage, and clinical variables with overall survival (OS), disease-free survival (DFS), and time to local recurrence (LR). Patients underwent protocol high-resolution pelvic MRI. Tumor distance to the mesorectal fascia of ≤ 1 mm was recorded as an MRI-involved CRM. A Cox proportional hazards model was used in multivariate analysis to determine the relationship of MRI assessment of CRM to survivorship after adjusting for preoperative covariates. Surviving patients were followed for a median of 62 months. The 5-year OS was 62.2% in patients with MRI-clear CRM compared with 42.2% in patients with MRI-involved CRM with a hazard ratio (HR) of 1.97 (95% CI, 1.27 to 3.04; P < .01). The 5-year DFS was 67.2% (95% CI, 61.4% to 73%) for MRI-clear CRM compared with 47.3% (95% CI, 33.7% to 60.9%) for MRI-involved CRM with an HR of 1.65 (95% CI, 1.01 to 2.69; P < .05). Local recurrence HR for MRI-involved CRM was 3.50 (95% CI, 1.53 to 8.00; P < .05). MRI-involved CRM was the only preoperative staging parameter that remained significant for OS, DFS, and LR on multivariate analysis. High-resolution MRI preoperative assessment of CRM status is superior to AJCC TNM-based criteria for assessing risk of LR, DFS, and OS. Furthermore, MRI CRM involvement is significantly associated with distant metastatic disease; therefore, colorectal cancer teams could intensify treatment and follow-up accordingly to improve survival outcomes.

  17. Influence of heat input and radius to pipe thickness ratio on the residual stresses in circumferential arc welded pipes of API X46 steels

    International Nuclear Information System (INIS)

    Hemmatzadeh, Majid; Moshayedi, Hessamoddin; Sattari-Far, Iradj

    2017-01-01

    The present work aims to study residual stresses caused by circumferentially welding of two similar API X46 steel pipes by means of finite element modeling. Considering the metallurgical phase transformations and through thermal-mechanical uncoupled analysis, the 3D modeling was carried out by SYSWELD software. Materialistic thermal and mechanical properties of all phases were defined in terms of temperature as well as phase transformation properties. Residual stress was measured through hole-drilling method. The obtained results were used to verify the finite element model. By means of full factorial experiment designing method, effects of heat input and radius to pipe thickness ratio on maximum values of hoop and axial residual stresses were investigated. The effect of each factor was studied in 3 levels and by 9 experiments. Results of statistical analysis revealed that increase in heat input and radius-thickness ratio would lead to higher values of maximum hoop and axial residual stresses. However, interactions of high level of heat input and a low level of radius-thickness ratio increased inter-pass temperature and consequently caused a sudden raise in maximum values of residual stresses. - Highlights: • A FEM model was developed to simulate welding considering phase transformations. • The obtained residual stresses were validated by experiments. • Effect of heat input and radius-to-thickness ratio on residual stress were investigated. • Increasing heat input for 100% caused increasing hoop and axial residual stress until 200%. • Interaction of high heat input and low R/t causes a sudden increase in axial residual stresses.

  18. Endoscopic Mucosal Resection with Circumferential Mucosal Incision for Colorectal Neoplasms: Comparison with Endoscopic Submucosal Dissection and between Two Endoscopists with Different Experiences

    Directory of Open Access Journals (Sweden)

    Dong-Hoon Yang

    2017-07-01

    Full Text Available Background/Aims Endoscopic mucosal resection with circumferential mucosal incision (CMI-EMR may offer benefits comparable to those of endoscopic submucosal dissection (ESD, while requiring less technical proficiency than ESD. Methods We retrospectively compared the outcomes of CMI-EMR (n=34 and size-matched ESD (n=102, which were performed by a Korean endoscopist for colorectal epithelial lesions of 20–35 mm. Procedural parameters of CMI-EMRs performed by an American ESD novice (n=30 were compared with those performed by the Korean endoscopist. Results The lesion size was 22.3±3.9 mm and 22.9±2.4 mm in the CMI-EMR and size-matched ESD groups, respectively (p=0.730. The resection time was 12.7±7.0 minutes in the CMI-EMR group and 45.6±30.1 minutes in the ESD group (p<0.001. The en bloc resection rate was 94.1% in the CMI-EMR group and 100% in the ESD group (p=0.061. There were no differences in the en bloc resection and complication rates of CMI-EMRs between a Korean and an American endoscopist. Conclusions For the treatment of moderate-size colorectal lesions, CMI-EMR showed a trend toward lower en bloc resection rate, but required shorter procedure time than ESD. CMI-EMR outcomes were similar when performed by a Korean ESD expert and an American ESD novice.

  19. The role of the laparoscopy on circumferential resection margin positivity in patients with rectal cancer: long-term outcomes at a single high-volume institution.

    Science.gov (United States)

    Dural, Ahmet C; Keskin, Metin; Balik, Emre; Akici, Murat; Kunduz, Enver; Yamaner, Sumer; Asoglu, Oktar; Gulluoglu, Mine; Bugra, Dursun

    2015-04-01

    The aim of this study was to evaluate the influence of laparoscopic rectal cancer surgery on circumferential resection margin (CRM) involvement. The data from 579 consecutive patients who underwent laparoscopic or open resection of rectal cancer from October 2002 to August 2008 were analyzed retrospectively. The primary endpoint was CRM status. The secondary endpoints were morbidity, local recurrence rate, overall survival, and disease-free survival. Laparoscopic resections were performed in 266 patients (46%), and the remainder of the patients underwent open resection. The rates of CRM involvement were similar between the laparoscopic and open groups (5.6% vs. 5.4%). The perioperative morbidity rates between the 2 groups were not significantly different (P=0.2). The incidence of local recurrence for the CRM-negative group was 8.4% (8.3% laparoscopic vs. 8.45% open; P=0.99), whereas the local recurrence rate was 34.3% for the CRM-positive group. The local recurrence rate was 20% for the CRM-positive patients in the laparoscopic group and 47% for the CRM-positive patients in the open group (PCRM status. CRM positivity was correlated with both 5-year survival and the 5-year disease-free survival rate (P=0.009 and P=0.001, respectively). We did not observe any significant differences in morbidity, local recurrence, or overall or disease-free survival rates between the overall laparoscopic and open resection groups. Laparoscopic surgery for rectal cancer is associated with similar complication rates, CRM involvement status, and long-term outcomes as those associated with open surgery but with the advantages of minimally invasive surgery. Although laparoscopic surgery might necessitate more advanced technical skills, similar long-term oncological results can be obtained with this technique.

  20. Extralevatory abdominoperineal excision (ELAPE) does not result in reduced rate of tumor perforation or rate of positive circumferential resection margin: a nationwide database study.

    Science.gov (United States)

    Klein, Mads; Fischer, Anders; Rosenberg, Jacob; Gögenur, Ismail

    2015-05-01

    To evaluate the oncological results and possible benefits associated with extralevatory abdominoperineal excision (ELAPE) when compared with conventional abdominoperineal excision (APE). ELAPE was introduced in 2007 with the purpose of reducing the rate of positive resection margins after resection of low rectal cancers. Preliminary studies have shown promising results. No large-scale or nationwide data have been presented. Database study based on data from the Danish Colorectal Cancer Group's prospective database. Data on all ELAPEs and APEs performed in Denmark in the period January 1, 2009, through August 2012 were retrieved and evaluated for differences in demography, tumor characteristics, and oncological results. Uni- and multivariate logistic regression analyses were performed to identify risk factors for resection with a positive circumferential resection margin (CRM+). A total of 554 patients were included, 301(54%) were operated by ELAPE; 253(46%) by APE. Sixty-three percent were men, median (interquartile range) age was 69 (61-76 years) years, and tumors removed had predominantly T-stages T2 and T3 (32% and 45%, respectively). Overall, CRM+ was found in 13% of patients. When divided according to type of procedure, we found no significant differences in demography and tumor T- and N-stages. Resections with a CRM+ were more common after ELAPE (16% vs 7%; P = 0.006). After uni- and multivariate logistic regression analyses, surgery by ELAPE remained a risk factor for a CRM+ [odds ratio, 2.59 (95% confidence interval, 1.31-5.12); P = 0.006). In this nationwide study, resection of low rectal cancers by ELAPE did not improve short-term oncological results, when compared with conventional APE.

  1. Working session 1: Tubing degradation

    International Nuclear Information System (INIS)

    Kharshafdjian, G.; Turluer, G.

    1997-01-01

    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 MESSclose 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

  2. Abiotic degradation of plastic films

    Science.gov (United States)

    Ángeles-López, Y. G.; Gutiérrez-Mayen, A. M.; Velasco-Pérez, M.; Beltrán-Villavicencio, M.; Vázquez-Morillas, A.; Cano-Blanco, M.

    2017-01-01

    Degradable plastics have been promoted as an option to mitigate the environmental impacts of plastic waste. However, there is no certainty about its degradability under different environmental conditions. The effect of accelerated weathering (AW), natural weathering (NW) and thermal oxidation (TO) on different plastics (high density polyethylene, HDPE; oxodegradable high density polyethylene, HDPE-oxo; compostable plastic, Ecovio ® metalized polypropylene, PP; and oxodegradable metalized polypropylene, PP-oxo) was studied. Plastics films were exposed to AW per 110 hours; to NW per 90 days; and to TO per 30 days. Plastic films exposed to AW and NW showed a general loss on mechanical properties. The highest reduction in elongation at break on AW occurred to HDPE-oxo (from 400.4% to 20.9%) and was higher than 90% for HDPE, HDPE-oxo, Ecovio ® and PP-oxo in NW. No substantial evidence of degradation was found on plastics exposed to TO. Oxo-plastics showed higher degradation rates than their conventional counterparts, and the compostable plastic was resistant to degradation in the studied abiotic conditions. This study shows that degradation of plastics in real life conditions will vary depending in both, their composition and the environment.

  3. 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.

  4. Assessment of the integrity of degraded steam generator tube by the use of heterogeneous finite element method

    International Nuclear Information System (INIS)

    Duan, X.; Kozluk, M.; Pagan, S.; Mills, B.

    2006-01-01

    Steam generator tubes at Ontario Power Generation (OPG) have been experiencing a variety of degradations such as pitting, fretting wear, erosion-corrosion, thinning and denting. To assist with steam generator life cycle management, OPG has developed Fitness-For-Service Guidelines (FFSG) for steam generator tubes. The FFSG are intended to provide standard acceptance criteria and evaluation procedures for assessing the condition of steam generator tubes for structural integrity, operational leak rate, and consequential leakage during an upset or abnormal event. Based on inspection results in conjunction with representative, postulated distributions of flaws in the un-inspected tubes, the FFSG provide an acceptable method of satisfying the intent of CSA-N285.4 and justifying the continued operation of degraded steam generator tubes. Some non-mandatory empirical axial and circumferential flaw models are also provided in the FFSG for structural integrity assessments. The test data from the OPG Steam Generator Tube Test Program (SGTTP) showed that the FFSG axial flaw model is conservative for a wide range of defect morphologies. A defect-specific axial flaw model was proposed for lattice-bar fret defects in I800 tubes by utilizing the SGTTP database of extensive test results. A defect-specific flaw model for outer diameter (OD) pitting and inner diameter (ID) intergranular attack in Monel 400 tubes was also developed using the SGTTP test data. More tests have been scheduled to support the development of defect specific models for axial flaws (OD cracks or ID laps) in Monel 400 and to supplement the database for Monel 400 pits. This paper explores the use of simulated testing for use in developing defect specific flaw models to reduce the amount of expensive tests. The Heterogeneous Finite Element Model (HFEM) has been developed and successfully applied to predict the failure behaviour of ductile metals under various deformation modes, i.e. plane stress, plane strain and

  5. Degradation of shape memory effect

    International Nuclear Information System (INIS)

    Vandermeer, R.A.

    1983-01-01

    An important parameter for deciding whether or not a SME alloy is suitable for practical applications is the magnitude of the strain reversal accompanying martensite reversion. This research is concerned with elucidating metallurgical factors that cause degradation of this heat-activated recovery strain, E/sub R/. After explaining what is meant by degradation, two manifestations of degradation recently identified in near-monotectoid uranium-niobium alloys are described. The first was associated with the onset of plastic deformation of the martensite beyond the reversible strain limit, E/sub L/; a reduction of E/sub R/ from 5.25% at 8% total strain, i.e. E/sub L/, to 2.9% at 12% total strain was observed. A second type of degradation depended strongly on the heating rate during reversion; the E/sub R/ for an imposed strain of 6.95% was reduced from a value of 5.25% to 1.3% when the heating rate was decreased from 40 0 /sec to 0.05 0 /sec. Degradation was attributed to a change in the transformation path and the interjection of time-dependent, low temperature aging reactions

  6. Clad Degradation - FEPs Screening Arguments

    International Nuclear Information System (INIS)

    E. Siegmann

    2004-01-01

    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])

  7. Radiation degradation of silk protein

    International Nuclear Information System (INIS)

    Pewlong, W.; Sudatis, B.; Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu

    2000-01-01

    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 2 /C 2 H 5 OH/H 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)

  8. 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)

  9. 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

  10. Diagnostic accuracy of computed tomography and magnetic resonance imaging obtained after neoadjuvant chemoradiotherapy in predicting the local tumor stage and circumferential resection margin status of rectal cancer

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin Hoon; Kim, Young Hoon; Lee, Yoon Jin; Lee, Kyoung Ho; Kang, Sung Bum; Kim, Duck Woo; Kim, Jae Hyun; Kim, Jae Sung; Lee, Hye Seung [Dept. of Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam (Korea, Republic of); Lee, Sang Min [Dept. of Radiology, Seoul National University Hospital, Seoul (Korea, Republic of)

    2014-02-15

    To measure the diagnostic accuracy of computed tomography (CT) and magnetic resonance imaging (MRI) obtained after neoadjuvant chemoradiotherapy (CRT) in patients with rectal cancer for a prediction of the local tumor stage and circumferential resection margin (CRM). Two independent radiologists reviewed CT and MRI obtained after neoadjuvant CRT. The accuracy of the local tumor staging and the diagnostic performance for the prediction of CRM involvement were calculated. The agreement between the measurements of the distance to potential CRM on both imaging modalities and the histopathology findings was assessed using Bland-Altman plots. 57 patients (mean age, 59.2 years; 24 females) were included. The accuracy of T and N staging were 43.9% (95% confidence interval, 30.8-57.7%) and 77.2% (64.2-87.3%) on CT and 63.2% (49.4-75.6%) and 77.2% (64.2-87.3%) on MRI for Observer 1. The accuracy of T and N staging were 54.4% (40.7-67.7%) and 77.2% (64.2-87.3%) on CT and 68.4% (54.7-80.1%) and 80.7% (68.1-90.0%) on MRI for Observer 2. Sensitivity and specificity on CRM involvement were 83.3% (43.7-97.0%) and 88.2% (76.6-94.5%) on CT and 100% (61.0-100%) and 90.2% (79.0-95.7%) on MRI for Observer 1. Sensitivity and specificity on CRM involvement were 66.7% (30.0-90.3%) and 88.2% (76.7-94.5%) on CT and 100% (61.0-100%) and 90.2% (79.0-95.7%) on MRI for Observer 2. Bland-Altman plots showed wide discrepancies between measurements of the distance to CRM on each CT and MRI and those on histopathology findings. CT and MRI showed limited performance in predicting the local tumor staging and CRM involvement in patients with neoadjuvant CRT although MRI tended to show a better performance than CT.

  11. Diagnostic accuracy of computed tomography and magnetic resonance imaging obtained after neoadjuvant chemoradiotherapy in predicting the local tumor stage and circumferential resection margin status of rectal cancer

    International Nuclear Information System (INIS)

    Park, Jin Hoon; Kim, Young Hoon; Lee, Yoon Jin; Lee, Kyoung Ho; Kang, Sung Bum; Kim, Duck Woo; Kim, Jae Hyun; Kim, Jae Sung; Lee, Hye Seung; Lee, Sang Min

    2014-01-01

    To measure the diagnostic accuracy of computed tomography (CT) and magnetic resonance imaging (MRI) obtained after neoadjuvant chemoradiotherapy (CRT) in patients with rectal cancer for a prediction of the local tumor stage and circumferential resection margin (CRM). Two independent radiologists reviewed CT and MRI obtained after neoadjuvant CRT. The accuracy of the local tumor staging and the diagnostic performance for the prediction of CRM involvement were calculated. The agreement between the measurements of the distance to potential CRM on both imaging modalities and the histopathology findings was assessed using Bland-Altman plots. 57 patients (mean age, 59.2 years; 24 females) were included. The accuracy of T and N staging were 43.9% (95% confidence interval, 30.8-57.7%) and 77.2% (64.2-87.3%) on CT and 63.2% (49.4-75.6%) and 77.2% (64.2-87.3%) on MRI for Observer 1. The accuracy of T and N staging were 54.4% (40.7-67.7%) and 77.2% (64.2-87.3%) on CT and 68.4% (54.7-80.1%) and 80.7% (68.1-90.0%) on MRI for Observer 2. Sensitivity and specificity on CRM involvement were 83.3% (43.7-97.0%) and 88.2% (76.6-94.5%) on CT and 100% (61.0-100%) and 90.2% (79.0-95.7%) on MRI for Observer 1. Sensitivity and specificity on CRM involvement were 66.7% (30.0-90.3%) and 88.2% (76.7-94.5%) on CT and 100% (61.0-100%) and 90.2% (79.0-95.7%) on MRI for Observer 2. Bland-Altman plots showed wide discrepancies between measurements of the distance to CRM on each CT and MRI and those on histopathology findings. CT and MRI showed limited performance in predicting the local tumor staging and CRM involvement in patients with neoadjuvant CRT although MRI tended to show a better performance than CT

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

    International Nuclear Information System (INIS)

    Rudling, P.

    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

  13. 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

  14. Degradation of materials and passivity

    International Nuclear Information System (INIS)

    Meisel, W.

    1997-01-01

    Demanding for a reduction in materials degradation is a serious problem all over the world. Moessbauer spectroscopy (MS) is, among others, a very valuable tool to follow many degradation processes. Evidently, Fe is the most important Moessbauer element considering the overall presence of iron in everyday life. MS may contribute to our knowledge about nearly all fields of materials degradation, chemical, mechanical, thermal, irradiative, etc. Following some general lines, corrosion is considered in particular. MS is applicable to investigate the bulk of materials as well as their surface layers with an information depth of ca. 250 nm. In general, it has to be applied as a surface sensitive method in combination with other relevant methods in order to get a detailed insight into ongoing processes. Some examples have been selected to elucidate the application of MS in this field. Another class of examples concerns attempts to prevent corrosion, i.e., the application of coatings and transforming chemicals. A very effective and most natural way to reduce corrosion is the passivation of materials. The effect of passive layers and their destruction by environmental influences are discussed using results of MS and related methods. It is outlined that passivity is not restricted to chemically treated metals but can be considered as a general concept for preventing different kinds of materials from degradation. (orig.)

  15. Land degradation and property regimes

    Science.gov (United States)

    Paul M. Beaumont; Robert T. Walker

    1996-01-01

    This paper addresses the relationship between property regimes and land degradation outcomes, in the context of peasant agriculture. We consider explicitly whether private property provides for superior soil resource conservation, as compared to common property and open access. To assess this we implement optimization algorithms on a supercomputer to address resource...

  16. Degradation of CIGS solar cells

    NARCIS (Netherlands)

    Theelen, M.J.

    2015-01-01

    Large scale commercial introduction of CIGS photovoltaics (PV) requires modules with low costs, high efficiencies and long and predictable lifetimes. Unfortunately,knowledge about the lifetime of CIGS PV is limited, which is reflected in the results of field studies: degradation rates varying from

  17. The Degradation of a Nation.

    Science.gov (United States)

    Morozova, Galina Fedorouna

    1995-01-01

    Maintains that the process of national degradation is a real danger and concern of all Russian society. Discusses environmental concerns, such as water, soil, and air pollution; falling birth rates; aging of the population; crime; and decline in moral values. Concludes that it is imperative for all citizens to stop and reverse these trends. (CFR)

  18. 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...

  19. Abiotic degradation of antibiotic ionophores

    DEFF Research Database (Denmark)

    Bohn, Pernille; Bak, Søren A; Björklund, Erland

    2013-01-01

    Hydrolytic and photolytic degradation were investigated for the ionophore antibiotics lasalocid, monensin, salinomycin, and narasin. The hydrolysis study was carried out by dissolving the ionophores in solutions of pH 4, 7, and 9, followed by incubation at three temperatures of 6, 22, and 28 °C f...... because they absorb light of environmentally irrelevant wavelengths....

  20. Advanced Oxidation Degradation of Diclofenac

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, William J., E-mail: wcooper@uci.edu [Urban Water Research Center, Department of Civil and Environmental Engineering, University of California, Irvine, CA 92697 (United States); Song Weihua, E-mail: wsong@fudan.edu.cn [Department of Environmental Science & Engineering, Fudan University, Shanghai 200433 (China)

    2012-07-01

    Advanced oxidation/reduction processes (AO/RPs), utilize free radical reactions to directly degrade chemical contaminants as an alternative to traditional water treatment. This study reports the absolute rate constants for reaction of diclofenac sodium and the model compound (2, 6-dichloraniline) with the two major AO/RP radicals; the hydroxyl radical (•OH) and hydrated electron (e{sup -}{sub aq}). The bimolecular reaction rate constants (M{sup -1} s{sup -1}) for diclofenac for •OH was (9.29 ± 0.11) x 10{sup 9}, and, for e- aq was (1.53 ± 0.03) x10{sup 9}. Preliminary degradation mechanisms are suggested based on product analysis using {sup 60}Co γ-irradiation and LC-MS for reaction by-product identification. The toxicity of products was evaluated using the Vibrio fischeri luminescent bacteria method. (author)

  1. Advanced Oxidation Degradation of Diclofenac

    International Nuclear Information System (INIS)

    Cooper, William J.; Song Weihua

    2012-01-01

    Advanced oxidation/reduction processes (AO/RPs), utilize free radical reactions to directly degrade chemical contaminants as an alternative to traditional water treatment. This study reports the absolute rate constants for reaction of diclofenac sodium and the model compound (2, 6-dichloraniline) with the two major AO/RP radicals; the hydroxyl radical (•OH) and hydrated electron (e - aq ). The bimolecular reaction rate constants (M -1 s -1 ) for diclofenac for •OH was (9.29 ± 0.11) x 10 9 , and, for e- aq was (1.53 ± 0.03) x10 9 . Preliminary degradation mechanisms are suggested based on product analysis using 60 Co γ-irradiation and LC-MS for reaction by-product identification. The toxicity of products was evaluated using the Vibrio fischeri luminescent bacteria method. (author)

  2. Fungal degradation of organophosphorous insecticides

    Energy Technology Data Exchange (ETDEWEB)

    Bumpus, J.A. [Notre Dame Univ., IN (United States); Kakar, S.N.; Coleman, R.D. [Argonne National Lab., IL (United States)

    1992-07-01

    Organophosphorous insecticides are used extensively to treat a variety of pests and insects. Although as a group they are easily degraded by bacteria in the environment, a number of them have half-lives of several months. Little is known about their biodegradation by fungi. We have shown that Phanerochaete chrysosporium can substantially degrade chlorpyrifos, fonofos, and terbufos (27.5%, 12.2%, and 26.6%, respectively) during 18-day incubation in nitrogen-limited stationary cultures. The results demonstrate that the clorinated pyridinyl ring of chlorpyrifos and the phenyl ring of fonofos undergo ring cleavage during biodegradation by the fungus. The usefulness of the fungus system for bioremediation is discussed. 16 refs., 7 figs., 2 tabs.

  3. Fungal degradation of organophosphorous insecticides

    Energy Technology Data Exchange (ETDEWEB)

    Bumpus, J.A. (Notre Dame Univ., IN (United States)); Kakar, S.N.; Coleman, R.D. (Argonne National Lab., IL (United States))

    1992-01-01

    Organophosphorous insecticides are used extensively to treat a variety of pests and insects. Although as a group they are easily degraded by bacteria in the environment, a number of them have half-lives of several months. Little is known about their biodegradation by fungi. We have shown that Phanerochaete chrysosporium can substantially degrade chlorpyrifos, fonofos, and terbufos (27.5%, 12.2%, and 26.6%, respectively) during 18-day incubation in nitrogen-limited stationary cultures. The results demonstrate that the clorinated pyridinyl ring of chlorpyrifos and the phenyl ring of fonofos undergo ring cleavage during biodegradation by the fungus. The usefulness of the fungus system for bioremediation is discussed. 16 refs., 7 figs., 2 tabs.

  4. 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)

  5. Degradation and inhibition of cyclooxygenase

    OpenAIRE

    Neuß, Heiko

    2011-01-01

    The cyclooxygenase (COX) is a central enzyme in the genesis of pain, inflammation and carcinogenesis. Two major isoforms, COX-1 and COX-2, have been described. The COX-1 is constitutively expressed in most tissues and has housekeeping functions, whereas the COX-2 is the inducible isoform, expressed under conditions of inflammation and tumor growth. First, we researched the degradation of the COX-2 enzyme. We were able to demonstrate, that the COX-2 protein was ubiquitinated before prote...

  6. Single gene retrieval from thermally degraded DNA

    Indian Academy of Sciences (India)

    Unknown

    DNA thermal degradation was shown to occur via a singlet oxygen pathway. A comparative study of the ther- mal degradation of cellular DNA and isolated DNA showed that cellular ..... definite level of energy (e.g. depurination active energy,.

  7. Extensions and applications of degradation modeling

    International Nuclear Information System (INIS)

    Hsu, F.; Subudhi, M.; Samanta, P.K.; Vesely, W.E.

    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, the authors discuss some of the extensions and applications of degradation modeling. The extensions and applications of the degradation modeling approaches discussed are: (a) theoretical developments to study reliability effects of different maintenance strategies and policies, (b) relating aging-failure rate to degradation rate, and (c) application to a continuously operating component

  8. 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

  9. Applications and extensions of degradation modeling

    International Nuclear Information System (INIS)

    Hsu, F.; Subudhi, M.; Samanta, P.K.; Vesely, W.E.

    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

  10. Degradation analysis of thin film photovoltaic modules

    International Nuclear Information System (INIS)

    Radue, C.; Dyk, E.E. van

    2009-01-01

    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 MAX ) of Si-1 was 9.92 W, with the initial light-induced degradation for Si-1 ∼30% and a total degradation of ∼42%. For Si-2 the initial P MAX was 7.93 W, with initial light-induced degradation of ∼10% and a total degradation of ∼17%. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Modelling land degradation in IMAGE 2

    NARCIS (Netherlands)

    Hootsmans RM; Bouwman AF; Leemans R; Kreileman GJJ; MNV

    2001-01-01

    Food security may be threatened by loss of soil productivity as a result of human-induced land degradation. Water erosion is the most important cause of land degradation, and its effects are irreversible. This report describes the IMAGE land degradation model developed for describing current and

  15. Using microorganisms to aid in hydrocarbon degradation

    International Nuclear Information System (INIS)

    Black, W.; Zamora, J.

    1993-01-01

    Aliphatic hydrocarbons are threatening the potable water supply and the aquatic ecosystem. Given the right microbial inhabitant(s), a large portion of these aliphatic hydrocarbons could be biodegraded before reaching the water supply. The authors' purpose is to isolate possible oil-degrading organisms. Soil samples were taken from hydrocarbon-laden soils at petroleum terminals, a petroleum refinery waste-treatment facility, a sewage-treatment plant grease collector, a site of previous bioremediation, and various other places. Some isolates known to be good degraders were obtained from culture collection services. These samples were plated on a 10w-30 multigrade motor oil solid medium to screen for aliphatic hydrocarbon degraders. The degrading organisms were isolated, identified, and tested (CO 2 evolution, BOD, and COD) to determine the most efficient degrader(s). Thirty-seven organisms were tested, and the most efficient degraders were Serratia marcescens, Escherichia coli, and Enterobacter agglomerans

  16. Enzymatic degradation of polycaprolactone–gelatin blend

    International Nuclear Information System (INIS)

    Banerjee, Aditi; Chatterjee, Kaushik; Madras, Giridhar

    2015-01-01

    Blends of polycaprolactone (PCL), a synthetic polymer and gelatin, natural polymer offer a optimal combination of strength, water wettability and cytocompatibility for use as a resorbable biomaterial. The enzymatic degradation of PCL, gelatin and PCL–gelatin blended films was studied in the presence of lipase (Novozym 435, immobilized) and lysozyme. Novozym 435 degraded the PCL films whereas lysozyme degraded the gelatin. Though Novozym 435 and lysozyme individually could degrade PCL–gelatin blended films, the combination of these enzymes showed the highest degradation of these blended films. Moreover, the enzymatic degradation was much faster when fresh enzymes were added at regular intervals. The changes in physico-chemical properties of polymer films due to degradation were studied by scanning electron microscopy, Fourier transform infrared spectroscopy and differential scanning calorimetry. These results have important implications for designing resorbable biomedical implants. (paper)

  17. Study of PP/montmorillonite composite degradation

    International Nuclear Information System (INIS)

    Baer, Marcia; Granado, Carlos J.F.

    2009-01-01

    The objective of this work was to produce composites of PP/sodium bentonite and PP/ organophilic bentonite through melt intercalation and analyze the degradation produced by ultraviolet irradiation. The XRD results showed that the samples of nature bentonite had better interaction with de polymer and produced intercalated nanocomposite. The effect of UV irradiation on degradation was observed after 24 hours of exposition. The samples showed the same photoproducts and at the same proportion until 240 hours of UV exposition; with 480 hours the organophilize bentonite composite showed higher degradation than other ones. The superficial cracks increased with degradation time. The degradation occurs due chromophores impurities presented in the samples, thus samples with sodium clay show higher degradation, and organophilic clay contains ammonium salt that contribute to increase the degradation. (author)

  18. STRUCTURAL PERFORMANCE OF DEGRADED REINFORCED CONCRETE MEMBERS

    International Nuclear Information System (INIS)

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

    2001-01-01

    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

  19. 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.

  20. 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.

  1. Charcoal production and environmental degradation

    International Nuclear Information System (INIS)

    Hosier, R.H.

    1993-01-01

    This paper examines the environmental impacts of continued tree harvesting for charcoal production to supply the urban areas in Tanzania. Woodlands appear to recover relatively well following harvesting for charcoal production. Selective harvesting, where the high quality, low cost fuel production species and specimens are culled first from a piece of land, serves to maintain the viability of the woodlands resource while providing charcoal. This recovery period can be prolonged through any number of human induced activities, such as heavy grazing, multiple burns and extended cultivation periods. At the same time, post-harvest management techniques, such as coppice management, sprout protection and fertilization, can also improve the ability of woodlands to recover following harvesting. The environmental history of a given area determines why certain areas continue to be strong suppliers of woodfuel while others are not. For example, Shinyanga started from a low productivity base and has been degraded by successive waves of tree harvesting compounded by heavy grazing pressure. It is this multiple complex of pressures over a long period of time on land which is intrinsically of low productivity, and not the harvesting of woodlands for fuels, which has led to the environmental degradation in these areas. (author)

  2. Microbial Enzymatic Degradation of Biodegradable Plastics.

    Science.gov (United States)

    Roohi; Bano, Kulsoom; Kuddus, Mohammed; Zaheer, Mohammed R; Zia, Qamar; Khan, Mohammed F; Ashraf, Ghulam Md; Gupta, Anamika; Aliev, Gjumrakch

    2017-01-01

    The renewable feedstock derived biodegradable plastics are important in various industries such as packaging, agricultural, paper coating, garbage bags and biomedical implants. The increasing water and waste pollution due to the available decomposition methods of plastic degradation have led to the emergence of biodegradable plastics and biological degradation with microbial (bacteria and fungi) extracellular enzymes. The microbes utilize biodegradable polymers as the substrate under starvation and in unavailability of microbial nutrients. Microbial enzymatic degradation is suitable from bioremediation point of view as no waste accumulation occurs. It is important to understand the microbial interaction and mechanism involved in the enzymatic degradation of biodegradable plastics under the influence of several environmental factors such as applied pH, thermo-stability, substrate molecular weight and/or complexity. To study the surface erosion of polymer film is another approach for hydrolytic degradation characteristion. The degradation of biopolymer is associated with the production of low molecular weight monomer and generation of carbon dioxide, methane and water molecule. This review reported the degradation study of various existing biodegradable plastics along with the potent degrading microbes (bacteria and fungi). Patents available on plastic biodegradation with biotechnological significance is also summarized in this paper. This paper assesses that new disposal technique should be adopted for the degradation of polymers and further research is required for the economical production of biodegradable plastics along with their enzymatic degradation. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  3. Bioresorption and degradation of biomaterials.

    Science.gov (United States)

    Das, Debarun; Zhang, Ziyang; Winkler, Thomas; Mour, Meenakshi; Gunter, Christina; Morlock, Michael; Machens, Hans-Gunther; Schilling, Arndt F

    2012-01-01

    The human body is a composite structure, completely constructed of biodegradable materials. This allows the cells of the body to remove and replace old or defective tissue with new material. Consequently, artificial resorbable biomaterials have been developed for application in regenerative medicine. We discuss here advantages and disadvantages of these bioresorbable materials for medical applications and give an overview of typically used metals, ceramics and polymers. Methods for the quantification of bioresorption in vitro and in vivo are described. The next challenge will be to better understand the interface between cell and material and to use this knowledge for the design of “intelligent” materials that can instruct the cells to build specific tissue geometries and degrade in the process.

  4. 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...... and the first author has been involved since 1970 in engineering geology, geotechnical engineering and permafrost related studies for foundation construction and infrastructures in towns and communities mainly in West Greenland. We have since 2006 together with the Danish Meteorological Institute, Greenland...... Survey (ASIAQ) and the University of Alaska Fairbanks carried out the US NSF funded project ARC-0612533: Recent and future permafrost variability, retreat and degradation in Greenland and Alaska: An integrated approach. This contribution will present data and observations from the towns Ilulissat...

  5. 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.

  6. Soil physical land degradation processes

    Science.gov (United States)

    Horn, Rainer

    2017-04-01

    According to the European Soil Framework Directive (2006) soil compaction is besides water and wind erosion one of the main physical reasons and threats of soil degradation. It is estimated, that 32% of the subsoils in Europe are highly degraded and 18% moderately vulnerable to compaction. The problem is not limited to crop land or forest areas (especially because of non-site adjusted harvesting machines) but is also prevalent in rangelands and grassland, and even in so called natural non-disturbed systems. The main reasons for an intense increase in compacted agricultural or forested regions are the still increasing masses of the machines as well the increased frequency of wheeling under non favorable site conditions. Shear and vibration induced soil deformation enhances the deterioration of soil properties especially if the soil water content is very high and the internal soil strength very low. The same is true for animal trampling in combination with overgrazing of moist to wet pastures which subsequently causes a denser (i.e. reduced proportion of coarse pores with smaller continuity) but still structured soil horizons and will finally end in a compacted platy structure. In combination with high water content and shearing due to trampling therefore results in a complete muddy homogeneous soil with no structure at all. (Krümmelbein et al. 2013) Site managements of arable, forestry or horticulture soils requires a sufficiently rigid pore system which guarantees water, gas and heat exchange, nutrient transport and adsorption as well as an optimal rootability in order to avoid subsoil compaction. Such pore system also guarantees a sufficient microbial activity and composition in order to also decompose the plant etc. debris. It is therefore essential that well structured horizons dominate in soils with at best subangular blocky structure or in the top A- horizons a crumbly structure due to biological activity. In contrast defines the formation of a platy

  7. Enzyme stabilization for pesticide degradation

    Energy Technology Data Exchange (ETDEWEB)

    Rivers, D.B.; Frazer, F.R. III; Mason, D.W.; Tice, T.R.

    1988-01-01

    Enzymes offer inherent advantages and limitations as active components of formulations used to decontaminate soil and equipment contaminated with toxic materials such as pesticides. Because of the catalytic nature of enzymes, each molecule of enzyme has the potential to destroy countless molecules of a contaminating toxic compound. This degradation takes place under mild environmental conditions of pH, temperature, pressure, and solvent. The basic limitation of enzymes is their degree of stability during storage and application conditions. Stabilizing methods such as the use of additives, covalent crosslinking, covalent attachment, gel entrapment, and microencapsulation have been directed developing an enzyme preparation that is stable under extremes of pH, temperature, and exposure to organic solvents. Initial studies were conducted using the model enzymes subtilisin and horseradish peroxidase.

  8. 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.

  9. The degradation of Brazilian socioeconomics

    Directory of Open Access Journals (Sweden)

    MARCUS ALBAN

    2018-03-01

    Full Text Available ABSTRACT In recent years, a number of illegal activities operated under the radar of conventional analysis have taken place in Brazil. This study proposes an Extended Keynesian Model in order to understand this phenomenon, a model that explains that crises happen because of the replacement of productive activities with unproductive and destructive activities. The model is used here to examine Brazil’s socioeconomic history since the institution of the economic plan that established the actual currency “Real” (R$, concluding that as the plan’s concern was predominantly with stabilization and not growth, productive activities have never been promoted on an appropriate scale. This has paved the way for the advancement of unproductive and destructive activities which have ultimately led to the country’s increasing degradation.

  10. Recovering of images degraded by atmosphere

    Science.gov (United States)

    Lin, Guang; Feng, Huajun; Xu, Zhihai; Li, Qi; Chen, Yueting

    2017-08-01

    Remote sensing images are seriously degraded by multiple scattering and bad weather. Through the analysis of the radiative transfer procedure in atmosphere, an image atmospheric degradation model considering the influence of atmospheric absorption multiple scattering and non-uniform distribution is proposed in this paper. Based on the proposed model, a novel recovering method is presented to eliminate atmospheric degradation. Mean-shift image segmentation and block-wise deconvolution are used to reduce time cost, retaining a good result. The recovering results indicate that the proposed method can significantly remove atmospheric degradation and effectively improve contrast compared with other removal methods. The results also illustrate that our method is suitable for various degraded remote sensing, including images with large field of view (FOV), images taken in side-glance situations, image degraded by atmospheric non-uniform distribution and images with various forms of clouds.

  11. Nanoparticles from Degradation of Biodegradable Plastic Mulch

    Science.gov (United States)

    Flury, Markus; Sintim, Henry; Bary, Andy; English, Marie; Schaefer, Sean

    2017-04-01

    Plastic mulch films are commonly used in crop production. They provide multiple benefits, including control of weeds and insects, increase of soil and air temperature, reduction of evaporation, and prevention of soil erosion. The use of plastic mulch film in agriculture has great potential to increase food production and security. Plastic mulch films must be retrieved and disposed after usage. Biodegradable plastic mulch films, who can be tilled into the soil after usage offer great benefits as alternative to conventional polyethylene plastic. However, it has to be shown that the degradation of these mulches is complete and no micro- and nanoparticles are released during degradation. We conducted a field experiment with biodegradable mulches and tested mulch degradation. Mulch was removed from the field after the growing season and composted to facilitate degradation. We found that micro- and nanoparticles were released during degradation of the mulch films in compost. This raises concerns about degradation in soils as well.

  12. 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.

  13. Robust PV Degradation Methodology and Application

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Dirk [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Deline, Christopher A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kurtz, Sarah [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kimball, Greg [SunPower; Anderson, Mike [SunPower

    2017-11-15

    The degradation rate plays an important role in predicting and assessing the long-term energy generation of PV systems. Many methods have been proposed for extracting the degradation rate from operational data of PV systems, but most of the published approaches are susceptible to bias due to inverter clipping, module soiling, temporary outages, seasonality, and sensor degradation. In this manuscript, we propose a methodology for determining PV degradation leveraging available modeled clear-sky irradiance data rather than site sensor data, and a robust year-over-year (YOY) rate calculation. We show the method to provide reliable degradation rate estimates even in the case of sensor drift, data shifts, and soiling. Compared with alternate methods, we demonstrate that the proposed method delivers the lowest uncertainty in degradation rate estimates for a fleet of 486 PV systems.

  14. CLAD DEGRADATION - FEPS SCREENING ARGUMENTS

    International Nuclear Information System (INIS)

    R. Schreiner

    2004-01-01

    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

  15. 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.

  16. 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.

  17. Diazotrophic Bacterial Community of Degraded Pastures

    OpenAIRE

    João Tiago Correia Oliveira; Everthon Fernandes Figueredo; Williane Patrícia da Silva Diniz; Lucianne Ferreira Paes de Oliveira; Pedro Avelino Maia de Andrade; Fernando Dini Andreote; Júlia Kuklinsky-Sobral; Danúbia Ramos de Lima; Fernando José Freire

    2017-01-01

    Pasture degradation can cause changes in diazotrophic bacterial communities. Thus, this study aimed to evaluate the culturable and total diazotrophic bacterial community, associated with regions of the rhizosphere and roots of Brachiaria decumbens Stapf. pastures in different stages of degradation. Samples of roots and rhizospheric soil were collected from slightly, partially, and highly degraded pastures. McCrady’s table was used to obtain the Most Probable Number (MPN) of bacteria per gram ...

  18. 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.

  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. 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.

  1. Degradation Mechanisms of Military Coating Systems

    National Research Council Canada - National Science Library

    Keene, L. T; Halada, G. P; Clayton, C. R; Kosik, W. E; McKnight, S. H

    2004-01-01

    This work describes the development and application of specialized characterization techniques used to study the environmental degradation mechanisms of organic coating systems employed by the United...

  2. Thermal degradation of glucosinolates in red cabbage

    NARCIS (Netherlands)

    Oerlemans, K.; Barrett, D.M.; Bosch Suades, C.; Verkerk, R.; Dekker, M.

    2006-01-01

    Thermal degradation of individual glucosinolates within the plant matrix was studied. Red cabbage samples were heated at different temperatures for various times. To rule out the influence of enzymatic breakdown and to focus entirely on the thermal degradation of glucosinolates, myrosinase was

  3. Degradation mechanisms in organic photovoltaic devices

    NARCIS (Netherlands)

    Grossiord, Nadia; Kroon, Jan M.; Andriessen, Ronn; Blom, Paul W. M.

    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

  4. 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 (H...

  5. Single gene retrieval from thermally degraded DNA

    Indian Academy of Sciences (India)

    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 ...

  6. Geodiversity and land degradation in Hungary

    Science.gov (United States)

    Őrsi, Anna

    2014-05-01

    Geodiversity represents a variety of natural values, but they are threatened by a series of anthropogenic activities and land degradation processes. Their effect depends on the intensity of the processes and the sensitivity of the area in question. As a consequence of land degradation processes not only biodiversity but also geodiversity can be damaged and deteriorated. The appearance of the natural landscape changes and natural processes may not have a decisive role in landscape development any more. Some of the damages are irreversible because fundamental changes happen in the landscape, or the processes having created the original forms are no longer in operation. Small scale land degradation processes may be reversible if nature is still capable of reproducing the original state. The most important land degradation processes are desertification and soil erosion. Mining, waste disposal, urbanisation and construction activities, agriculture, inaccurate forest and water management, tourism, unsuitable land use can also lead to severe land degradation problems. The objective of the paper is to show Hungarian examples to all land degradation processes that threaten geodiversity. The results will be shown on a series of maps showing land degradation processes endangering geodiversity in Hungary. A detailed analysis of smaller study sites will be provided to show the effects of certain land degradation processes on landform development and on the changes of geodiversity. This research is supported by the Hungarian Scientific Research Fund (OTKA), project Nr. 10875.

  7. A systems approach to restoring degraded drylands

    Science.gov (United States)

    Jeremy J. James; Roger L. Sheley; Todd Erickson; Kimberly S. Rollins; Michael H. Taylor; Kingsley W. Dixon

    2013-01-01

    Drylands support over 2 billion people and are major providers of critical ecosystem goods and services across the globe. Drylands, however, are one of the most susceptible biomes to degradation. International programmes widely recognize dryland restoration as key to combating global dryland degradation and ensuring future global sustainability. While the need to...

  8. Lignin-degrading enzyme activities.

    Science.gov (United States)

    Chen, Yi-ru; Sarkanen, Simo; Wang, Yun-Yan

    2012-01-01

    Over the past three decades, the activities of four kinds of enzyme have been purported to furnish the mechanistic foundations for macromolecular lignin depolymerization in decaying plant cell walls. The pertinent fungal enzymes comprise lignin peroxidase (with a relatively high redox potential), manganese peroxidase, an alkyl aryl etherase, and laccase. The peroxidases and laccase, but not the etherase, are expressed extracellularly by white-rot fungi. A number of these microorganisms exhibit a marked preference toward lignin in their degradation of lignocellulose. Interestingly, some white-rot fungi secrete both kinds of peroxidase but no laccase, while others that are equally effective express extracellular laccase activity but no peroxidases. Actually, none of these enzymes has been reported to possess significant depolymerase activity toward macromolecular lignin substrates that are derived with little chemical modification from the native biopolymer. Here, the assays commonly employed for monitoring the traditional fungal peroxidases, alkyl aryl etherase, and laccase are described in their respective contexts. A soluble native polymeric substrate that can be isolated directly from a conventional milled-wood lignin preparation is characterized in relation to its utility in next-generation lignin-depolymerase assays.

  9. Synaptic Synthesis, Dephosphorylation, and Degradation

    Science.gov (United States)

    La Montanara, Paolo; Rusconi, Laura; Locarno, Albina; Forti, Lia; Barbiero, Isabella; Tramarin, Marco; Chandola, Chetan; Kilstrup-Nielsen, Charlotte; Landsberger, Nicoletta

    2015-01-01

    Mutations in the X-linked CDKL5 (cyclin-dependent kinase-like 5) gene have been associated with several forms of neurodevelopmental disorders, including atypical Rett syndrome, autism spectrum disorders, and early infantile epileptic encephalopathy. Accordingly, loss of CDKL5 in mice results in autistic-like features and impaired neuronal communication. Although the biological functions of CDKL5 remain largely unknown, recent pieces of evidence suggest that CDKL5 is involved in neuronal plasticity. Herein, we show that, at all stages of development, neuronal depolarization induces a rapid increase in CDKL5 levels, mostly mediated by extrasomatic synthesis. In young neurons, this induction is prolonged, whereas in more mature neurons, NMDA receptor stimulation induces a protein phosphatase 1-dependent dephosphorylation of CDKL5 that is mandatory for its proteasome-dependent degradation. As a corollary, neuronal activity leads to a prolonged induction of CDKL5 levels in immature neurons but to a short lasting increase of the kinase in mature neurons. Recent results demonstrate that many genes associated with autism spectrum disorders are crucial components of the activity-dependent signaling networks regulating the composition, shape, and strength of the synapse. Thus, we speculate that CDKL5 deficiency disrupts activity-dependent signaling and the consequent synapse development, maturation, and refinement. PMID:25555910

  10. Degraded character recognition based on gradient pattern

    Science.gov (United States)

    Babu, D. R. Ramesh; Ravishankar, M.; Kumar, Manish; Wadera, Kevin; Raj, Aakash

    2010-02-01

    Degraded character recognition is a challenging problem in the field of Optical Character Recognition (OCR). The performance of an optical character recognition depends upon printed quality of the input documents. Many OCRs have been designed which correctly identifies the fine printed documents. But, very few reported work has been found on the recognition of the degraded documents. The efficiency of the OCRs system decreases if the input image is degraded. In this paper, a novel approach based on gradient pattern for recognizing degraded printed character is proposed. The approach makes use of gradient pattern of an individual character for recognition. Experiments were conducted on character image that is either digitally written or a degraded character extracted from historical documents and the results are found to be satisfactory.

  11. Quantitative accelerated degradation testing: Practical approaches

    International Nuclear Information System (INIS)

    Mohammadian, S. Hossein; Ait-Kadi, Daoud; Routhier, Francois

    2010-01-01

    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.

  12. Degradation of multiwall carbon nanotubes by bacteria

    International Nuclear Information System (INIS)

    Zhang, Liwen; Petersen, Elijah J.; Habteselassie, Mussie Y.; Mao, Liang; Huang, Qingguo

    2013-01-01

    Understanding the environmental transformation of multiwall carbon nanotubes (MWCNTs) is important to their life cycle assessment and potential environmental impacts. We report that a bacterial community is capable of degrading 14 C-labeled MWCNTs into 14 CO 2 in the presence of an external carbon source via co-metabolism. Multiple intermediate products were detected, and genotypic characterization revealed three possible microbial degraders: Burkholderia kururiensis, Delftia acidovorans, and Stenotrophomonas maltophilia. This result suggests that microbe/MWCNTs interaction may impact the long-term fate of MWCNTs. Highlights: •Mineralization of MWCNTs by a bacterial community was observed. •The mineralization required an external carbon source. •Multiple intermediate products were identified in the MWCNT degrading culture. •Three bacterial species were found likely responsible for MWCNT degradation. -- The 14 C-labeled multiwall carbon nanotubes can be degraded to 14 CO 2 and other byproducts by a bacteria community under natural conditions

  13. 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)

  14. Degradation of chlorocarbons driven by hydrodynamic cavitation

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Z.L.; Ondruschka, B.; Braeutigam, P. [Institut fuer Technische Chemie und Umweltchemie, Friedrich-Schiller-Universitaet Jena, Jena (Germany)

    2007-05-15

    To provide an efficient lab-scale device for the investigation of the degradation of organic pollutants driven by hydrodynamic cavitation, the degradation kinetics of chloroform and carbon tetrachloride and the increase of conductivity in aqueous solutions were measured. These are values which were not previously available. Under hydrodynamic cavitation conditions, the degradation kinetics for chlorocarbons was found to be pseudo first-order. Meanwhile, C-H and C-Cl bonds are broken, and Cl{sub 2}, Cl{sup .}, Cl{sup -} and other ions released can increase the conductivity and enhance the oxidation of KI in aqueous solutions. The upstream pressures of the orifice plate, the cavitation number, and the solution temperature have substantial effects on the degradation kinetics. A decreased cavitation number can result in more cavitation events and enhances the degradation of chlorocarbons and/or the oxidation of KI. A decrease in temperature is generally favorable to the cavitation chemistry. Organic products from the degradation of carbon tetrachloride and chloroform have demonstrated the formation and recombination of free radicals, e.g., CCl{sub 4}, C{sub 2}Cl{sub 4}, and C{sub 2}Cl{sub 6} are produced from the degradation of CHCl{sub 3}. CHCl{sub 3} and C{sub 2}Cl{sub 6} are produced from the degradation of CCl{sub 4}. Both the chemical mechanism and the reaction kinetics of the degradation of chlorocarbons induced by hydrodynamic cavitation are consistent with those obtained from the acoustic cavitation. Therefore, the technology of hydrodynamic cavitation should be a good candidate for the removal of organic pollutants from water. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  15. Radiation degradation of short-cotton linters

    International Nuclear Information System (INIS)

    Ma Zue Teh; Zhou Rui Min

    1984-01-01

    Radiation degradation of short-cotton linters has been studied by using X-ray diffraction, an infrared spectrometer and a viscosimeter. Average molecular weight and crystallinity of short-cotton linters and the change of reducing sugar in γ-radiation degradation were examined. It was found that cellulosic saccharification in hydrolysis was enhanced with preirradiation of linter. This probably resulted from the radiation induced change of cellulosic structure. Sensitizers to promote radiation degradation effect were investigated. Carbon tetrachloride has been found to be effective. (author)

  16. 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.

  17. 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.

  18. Radiation damage calculations for the LANSCE degrader

    International Nuclear Information System (INIS)

    Ferguson, P.D.; Sommer, W.F.; Dudziak, D.J.; Wechsler, M.S.; Barnett, M.H.; Corzine, R.K.

    1998-01-01

    The A-6 water degrader at the Los Alamos Neutron Science Center (LANSCE) linear proton accelerator has an outer shell of Inconel 718. The degrader was irradiated by 800-MeV protons during 1988--1993 to an exposure of 5.3 ampere-hours (A h). As described in Ref. 1, material from the Inconel is currently being cut into specimens for microhardness, three-point bending, ball punch, microscopy, and corrosion tests. This paper is devoted to calculations of radiation damage, particularly displacement and He production, sustained by the degrader Inconel

  19. 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....

  20. Polycyclic aromatic hydrocarbons degradation by marine-derived basidiomycetes: optimization of the degradation process.

    Science.gov (United States)

    Vieira, Gabriela A L; Magrini, Mariana Juventina; Bonugli-Santos, Rafaella C; Rodrigues, Marili V N; Sette, Lara D

    2018-05-03

    Pyrene and benzo[a]pyrene (BaP) are high molecular weight polycyclic aromatic hydrocarbons (PAHs) recalcitrant to microbial attack. Although studies related to the microbial degradation of PAHs have been carried out in the last decades, little is known about degradation of these environmental pollutants by fungi from marine origin. Therefore, this study aimed to select one PAHs degrader among three marine-derived basidiomycete fungi and to study its pyrene detoxification/degradation. Marasmiellus sp. CBMAI 1062 showed higher levels of pyrene and BaP degradation and was subjected to studies related to pyrene degradation optimization using experimental design, acute toxicity, organic carbon removal (TOC), and metabolite evaluation. The experimental design resulted in an efficient pyrene degradation, reducing the experiment time while the PAH concentration applied in the assays was increased. The selected fungus was able to degrade almost 100% of pyrene (0.08mgmL -1 ) after 48h of incubation under saline condition, without generating toxic compounds and with a TOC reduction of 17%. Intermediate metabolites of pyrene degradation were identified, suggesting that the fungus degraded the compound via the cytochrome P450 system and epoxide hydrolases. These results highlight the relevance of marine-derived fungi in the field of PAH bioremediation, adding value to the blue biotechnology. Copyright © 2018. Published by Elsevier Editora Ltda.

  1. Method of degrading pollutants in soil

    Science.gov (United States)

    Hazen, Terry C.; Lopez-De-Victoria, Geralyne

    1994-01-01

    A method and system for enhancing the motility of microorganisms by placing an effective amount of chlorinated hydrocarbons, preferably chlorinated alkenes, and most preferably trichloroethylene in spaced relation to the microbes so that the surprisingly strong, monomodal, chemotactic response of the chlorinated hydrocarbon on subsurface microbes can draw the microbes away from or towards and into a substance, as desired. In remediation of groundwater pollution, for example, TCE can be injected into the plume to increase the population of microbes at the plume whereby the plume can be more quickly degraded. A TCE-degrading microbe, such as Welchia alkenophilia, can be used to degrade the TCE following the degradation of the original pollutant.

  2. 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.

  3. 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...

  4. Polymer Composites Corrosive Degradation: A Computational Simulation

    Science.gov (United States)

    Chamis, Christos C.; Minnetyan, Levon

    2007-01-01

    A computational simulation of polymer composites corrosive durability is presented. The corrosive environment is assumed to manage the polymer composite degradation on a ply-by-ply basis. The degradation is correlated with a measured pH factor and is represented by voids, temperature and moisture which vary parabolically for voids and linearly for temperature and moisture through the laminate thickness. The simulation is performed by a computational composite mechanics computer code which includes micro, macro, combined stress failure and laminate theories. This accounts for starting the simulation from constitutive material properties and up to the laminate scale which exposes the laminate to the corrosive environment. Results obtained for one laminate indicate that the ply-by-ply degradation degrades the laminate to the last one or the last several plies. Results also demonstrate that the simulation is applicable to other polymer composite systems as well.

  5. Stability and Degradation of Polymer Solar cells

    DEFF Research Database (Denmark)

    Norrman, Kion

    The current state-of-the-art allows for roll-to-roll manufacture of polymer solar cells in high volume with stability and efficiency sufficient to grant success in low-energy applications. However, further improvement is needed for the successful application of the devices in real life applications....... This is obtained by detailed knowledge of the degradation mechanisms. Methods to compare and standardize device stability are urgently needed. Methodologies to study failure mechanism that are based on physical processes (e.g. morphological changes) are well-established. However, methodologies to study chemical...... degradation mechanisms are currently scarce. An overview of known degradation mechanisms will be presented and discussed in relation to state-of-the-art methodologies to study failure mechanisms with focus on chemical degradation....

  6. Degradation Behavior of Thermal Stabilized Polyacrylonitrile Fibers

    Directory of Open Access Journals (Sweden)

    LEI Shuai

    2017-05-01

    Full Text Available In the temperature range of 300-800℃, 40%-50% of the mass lost during the processing of polyacrylonitrile based carbon fiber (PANCF. Understanding the degradation behavior will be valuable in understanding the formation mechanism of pseudo-graphite structure, and providing theoretic basis for producing high performance carbon fiber and increasing the carbonization yield. The simulation of the degradation progress was carried out on the thermogravimetric analyzer (TGA, the results show that there are two degradation steps for PAN fiber stabilized in air, and controlled by cyclization coefficient and oxygen content. The cyclization coefficient and oxygen content are effective to the density of carbon fiber by influencing the degradation behavior, which cause defects in the fiber. The higher cyclization coefficient leads to form less structural defects and higher density of the fiber; on the contrary, the higher oxygen content leads to form more structural defects and lower density of the fiber.

  7. Degradation characteristics of waste polyurethane by radiation

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jong Seok; Ahn, Sung Jun; Gwon Hui Jeong; Jeong, Sung In; Nho, Young Chang; Lim, Youn Mook [Research Division for Industry and Environment, Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2017-06-15

    Polyurethane (PU) is a very popular polymer that is used in a variety of applications due to its good mechanical, thermal, and chemical properties. However, waste PU recycling has received significant attention due to environmental issues. The aim of this work was to investigate the degradation characteristics of waste PU to recycle. Degradation of waste PU was carried out using a radiation techniques. Waste PUs were exposed to a gamma {sup 60}Co sources. To verify degradation, the irradiated PUs were characterized using FT-IR, gel permeation chromatography (GPC), and their thermal/mechanical properties are reported. When the radiation dose was 500 kGy, the molecular weight of the waste PU drastically decreased. Also, the mechanical properties of waste PU were approximately 4 times lower than those of non-irradiated PU. This study has confirmed the possibility of making fine particle of waste PU for recycling through radiation degradation techniques.

  8. Degradation mechanisms of small scale piping systems

    International Nuclear Information System (INIS)

    Bartonicek, J.; Koenig, G.; Blind, D.

    1996-01-01

    Operational experience shows that many degradation mechanisms can have an effect on small-scale piping systems. We can see from the analyses carried out that the degradation which has occurred is primarily linked with the fact that these piping systems were classified as being of low safety relevance. This is mainly due to such components being classified into low safety relevance category at the design stage, as well as to the low level of operational monitoring. Since in spite of the variety of designs and operational modes the degradation mechanisms detected may be attributed to the piping systems, we can make decisive statements on how to avoid such degradation mechanisms. Even small-scale piping systems may achieve guaranteed integrity in such cases by taking the appropriate action. (orig.) [de

  9. ESR studies on degradation processes in polyethyleneterephtalate

    International Nuclear Information System (INIS)

    Chipara, M.; Chipara, M.D.; Georgescu, L.; Constantinescu, L.; Morosanu, C.

    2002-01-01

    Complete text of publication follows. The generation of free radicals by degradation processes (thermal, plasma and radiation induced) is analyzed. Details regarding the generation of free radicals, their interactions, and kinetics, as revealed by electron spin resonance (ESR), with emphasis on laser beam degradation, are discussed. Some ESR lines of laser-irradiated polyethyleneterephtalate (PET), recorded at room temperature, are shown in Figure 1. The lines are narrow singlets located around g=2.003. The resonance line amplitude, width and double integral of the resonance line are affected by the power of the incident beam. The common features of these degradation processes (universal behavior) as well as the fingerprints of each degradation process are analyzed in detail

  10. Aggradation, Degradation, and Water Quality Conditions

    National Research Council Canada - National Science Library

    1993-01-01

    The purpose of this study is to compile a record of pertinent data and information relative to aggradation, degradation, and water quality within the system of six Missouri River mainstem reservoirs...

  11. 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...

  12. 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...

  13. Degradation of magnetite nanoparticles in biomimetic media

    Energy Technology Data Exchange (ETDEWEB)

    Briceño, Sarah; Hernandez, Ana C.; Sojo, Juan [Instituto Venezolano de Investigaciones Científicas (IVIC), Laboratorio de Materiales, Centro de Ingeniería de Materiales y Nanotecnología (Venezuela, Bolivarian Republic of); Lascano, Luis [Dpto. Física, Escuela Politécnica Nacional (Ecuador); Gonzalez, Gema, E-mail: gemagonz@ivic.gob.ve, E-mail: gema.gonzalez@epn.edu.ec [Escuela Nacional Politécnica (Ecuador)

    2017-04-15

    Magnetic nanoparticles (NPs) of magnetite Fe{sub 3}O{sub 4} obtained by coprecipitation (COP), thermal decomposition (DT), and commercial sample (CM) have been degraded in similar conditions to physiological medium at pH 4.7 and in simulated body fluid (SBF) at pH 7.4. The formation of the nanoparticles was confirmed by FTIR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). In view of medical and environmental applications, the stability of the particles was measured with dynamic light scattering. The degradation processes were followed with atomic absorption spectroscopy (EAA) and TEM. Magnetic measurements were carried out using vibrating sample magnetometry (VSM). Our results revealed that the structural and magnetic properties of the remaining nanoparticles after the degradation process were significantly different to those of the initial suspension. The degradation kinetics is affected by the pH, the coating, and the average particle size of the nanoparticles.

  14. PHOTOCATALYTIC DEGRADATION OF CRYSTAL VIOLET BY ...

    African Journals Online (AJOL)

    In recent years, removal of undesirable organic contaminants from water and wastewater is ... accidental leakage of tanks containing pollutants, etc. ..... Consideration of reaction pathways and degradation rates is critical for detection of waste.

  15. Phytohormone and Light Regulation of Chlorophyll Degradation

    Directory of Open Access Journals (Sweden)

    Xiaoyu Zhu

    2017-11-01

    Full Text Available Degreening, due to the net loss of chlorophyll (Chl, is the most prominent symptom during the processes of leaf senescence, fruit ripening, and seed maturation. Over the last decade or so, extensive identifications of Chl catabolic genes (CCGs have led to the revelation of the biochemical pathway of Chl degradation. As such, exploration of the regulatory mechanism of the degreening process is greatly facilitated. During the past few years, substantial progress has been made in elucidating the regulation of Chl degradation, particularly via the mediation of major phytohormones' signaling. Intriguingly, ethylene and abscisic acid's signaling have been demonstrated to interweave with light signaling in mediating the regulation of Chl degradation. In this review, we briefly summarize this progress, with an effort on providing a framework for further investigation of multifaceted and hierarchical regulations of Chl degradation.

  16. Concrete performance using low-degradation aggregates.

    Science.gov (United States)

    2012-06-01

    The durability of Portland cement concrete (PCC) has long been identified as a concern by transportation communities around the United States. In this study, the long-term performance of two batches of concrete incorporating either low-degradation (L...

  17. Implications for Forest Resource Degradation and Deforestation ...

    African Journals Online (AJOL)

    Effects of Socio-Economic Status and Food Consumption Pattern on Household Energy uses: Implications for Forest Resource Degradation and Deforestation around Wondo Genet Catchments, South-Central Ethiopia.

  18. Polycyclic aromatic hydrocarbons (PAHs) degradation by laccase ...

    African Journals Online (AJOL)

    PRECIOUS

    2009-11-02

    Nov 2, 2009 ... Full Length Research Paper. Polycyclic aromatic ... production of paper, feeds, chemicals and fuels there is ... microbes with the production of lignin-modifying enzymes ... enable white rot fungi to degrade a variety of toxic.

  19. Method of degrading pollutants in soil

    Science.gov (United States)

    Hazen, T.C.; Lopez-De-Victoria, G.

    1994-07-05

    Disclosed are a method and system for enhancing the motility of microorganisms. This is accomplished by placing an effective amount of chlorinated hydrocarbons, preferably chlorinated alkenes, and most preferably trichloroethylene in spaced relation to the microbes so that the surprisingly strong, monomodal, chemotactic response of the chlorinated hydrocarbon on subsurface microbes can draw the microbes away from or towards and into a substance, as desired. In remediation of groundwater pollution, for example, TCE can be injected into the plume to increase the population of microbes at the plume whereby the plume can be more quickly degraded. A TCE-degrading microbe, such as Welchia alkenophilia, can be used to degrade the TCE following the degradation of the original pollutant. 5 figures.

  20. Degradation of Waterfront Reinforced Concrete Structures

    African Journals Online (AJOL)

    Key words: Degradation, reinforced concrete, Dar es Salaam port. Abstract—One of the ... especially corrosion of the reinforcement. ... Corrosion of steel reinforcement contributes .... cracks along the line of reinforcement bars and most of the ...

  1. 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

  2. Degradation of hop bitter acids by fungi

    International Nuclear Information System (INIS)

    Huszcza, Ewa; Bartmanska, Agnieszka; Aniol, Miroslaw; Maczka, Wanda; Zolnierczyk, Anna; Wawrzenczyk, Czeslaw

    2008-01-01

    Nine fungal strains related to: Trametes versicolor, Nigrospora oryzae, Inonotus radiatus, Crumenulopsis sororia, Coryneum betulinum, Cryptosporiopsis radicicola, Fusarium equiseti, Rhodotorula glutinis and Candida parapsilosis were tested for their ability to degrade humulones and lupulones. The best results were obtained for T. versicolor culture, in which humulones and lupulones were fully degraded after 4 days of incubation in the dark or after 36 h in the light. The experiments were performed on a commercial hop extract and on sterilized spent hops

  3. Increased radiation degradation in methyl methacrylate copolymers

    International Nuclear Information System (INIS)

    Helbert, J.N; Wagner, G.E.; Caplan, P.J.; Poindexter, E.H.

    1975-01-01

    The effect of polar substituents at the quaternary carbon on degradation processes in several polymers and 10 to 20 percent copolymers of methyl methacrylate was explored. EPR was used to monitor radiation degradation products and to determine radiation G values. Irradiations were carried out at 77 0 K in a gamma irradiator at a dose rate of 0.3 Mrad/hr. (U.S.)

  4. Accelerated Testing Of Photothermal Degradation Of Polymers

    Science.gov (United States)

    Kim, Soon Sam; Liang, Ranty Hing; Tsay, Fun-Dow

    1989-01-01

    Electron-spin-resonance (ESR) spectroscopy and Arrhenius plots used to determine maximum safe temperature for accelerated testing of photothermal degradation of polymers. Aging accelerated by increasing illumination, temperature, or both. Results of aging tests at temperatures higher than those encountered in normal use valid as long as mechanism of degradation same throughout range of temperatures. Transition between different mechanisms at some temperature identified via transition between activation energies, manifesting itself as change in slope of Arrhenius plot at that temperature.

  5. Microstructure and Ductility-Dip Cracking Susceptibility of Circumferential Multipass Dissimilar Weld Between 20MND5 and Z2CND18-12NS with Ni-Base Filler Metal 52

    Science.gov (United States)

    Qin, Renyao; Duan, Zhaoling; He, Guo

    2013-10-01

    The large circumferential multipass dissimilar weld between 20MND5 steel and Z2CND18-12NS stainless steel welded with FM52 filler material was investigated in terms of the diluted composition, the grain boundary precipitation, and the ductility-dip cracking (DDC) susceptibility of the weld. The diluted composition of the weld is composed of 37 to 47 pct Ni, 21 to 24 pct Cr, and 28 to 40 pct Fe, which are inhomogeneous along the depth and over the width of the deep weld. The carbon content has a distribution in the region of the surface weld from a high level (~0.20 pct) in the zone near 20MND5 steel to a normal level (~0.03 pct) in the zone near Z2CND18-12NS stainless steel. The carbon distribution is corresponding to the grain boundary carbides. The minimum threshold strains for DDC occur in the temperature range of 1223 K to 1323 K (950 °C to 1050 °C), which are 0.5, 0.35, and 0.4 pct for the root weld, middle region, and the surface weld, respectively. The dissimilar weld has the largest susceptibility to the DDC compared to the filler metal 52 and the Inconel 690.

  6. Circumferential welding applied for inox steel super duplex UNS S32750 using the process MIG using CMT® control; Soldagem circunferencial do aço inoxidável super duplex UNS S32750 pelo processo MIG com controle CMT®

    Energy Technology Data Exchange (ETDEWEB)

    Invernizzi, Bruno Pizol

    2017-07-01

    This study carried out circumferential welding experiments in UNS S32750 Super Duplex Stainless Steel tubes using diameters of 19,05 mm and 48,20 mm. Welds were performed using various welding parameters on a MIG machine with Cold Metal Transfer® CMT control. The weld joints were evaluated by visual and dimensional inspection in addition to the Vickers microhardness and traction tests, as well as the microstructural analysis in conjunction with phase precipitation analysis, which was performed according to practice A of ASTM A923, and corrosion test in accordance with practice A of ASTM G48 in conjunction with ASTM A923. The results indicated that welds performed in pipes with a diameter of 19.05 mm showed a weld joint with unacceptable dimensions according to the standard, this condition being attributed the use of a high wire diameter for the welding conditions used. Welding performed for pipes with a diameter of 48.20 mm showed a lack of penetration under the conditions employed when welded by the conventional CMT® process. In the case of the use of CMT® combined with pulsed arc, under conditions that generated greater heat input during welding, this resulted in total penetration of the joint and adequate surface finish. The results indicated that welding using the CMT® process combined with pulsed arc, under the conditions (parameters) employed generated good surface finish, combined mechanical properties, meeting standards requirements, as well as a balanced microstructure and high resistance to corrosion. (author)

  7. Simulation and analysis of the thermal and deformation behaviour of `as-received` and `hydrided` pressure tubes used in the circumferential temperature distribution experiments (end of life/pressure tube behaviour)

    Energy Technology Data Exchange (ETDEWEB)

    Muir, W C; Bayoumi, M H [Ontario Hydro, Toronto, ON (Canada)

    1996-12-31

    It is postulated that in-reactor pressure tubes may be subjected to radiation damage and dissolved deuterium which could change the pressure tube characteristics and lead to different behaviour than that of as-received pressure tubes under large LOCA (loss of coolant) conditions. A hydrided pressure tube was used to study the effect of dissolved hydrogen on thermal-mechanical behaviour. In the experiment, simulating an in-reactor (hydrided) pressure tube with circumferential differential temperature under boil-off conditions, the pressure tube ballooned into contact with the calandria tube. The pressure tube used in this experiment was hydrided in a furnace to a nominal value of 200 {mu}g/g dissolved hydrogen. This test was a repeat of the first supplementary boil-off test (S-5-1) which used an as-received pressure tube. The objective of this paper is to analyze the results obtained from the simulation of this Boil-Off test using the SMARTT computer code and to examine the effect of hydriding on the thermal and ballooning behaviour of the pressure tube by comparison with the results obtained from test S-5-1. A discussion of the results obtained from this comparison is presented together with an analysis of their application to the analysis of pressure tube behaviour in CANDU reactors. (author). 13 refs., 1 tab., 16 figs.

  8. Simulation and analysis of the thermal and deformation behaviour of 'as-received' and 'hydrided' pressure tubes used in the circumferential temperature distribution experiments (end of life/pressure tube behaviour)

    International Nuclear Information System (INIS)

    Muir, W.C.; Bayoumi, M.H.

    1995-01-01

    It is postulated that in-reactor pressure tubes may be subjected to radiation damage and dissolved deuterium which could change the pressure tube characteristics and lead to different behaviour than that of as-received pressure tubes under large LOCA (loss of coolant) conditions. A hydrided pressure tube was used to study the effect of dissolved hydrogen on thermal-mechanical behaviour. In the experiment, simulating an in-reactor (hydrided) pressure tube with circumferential differential temperature under boil-off conditions, the pressure tube ballooned into contact with the calandria tube. The pressure tube used in this experiment was hydrided in a furnace to a nominal value of 200 μg/g dissolved hydrogen. This test was a repeat of the first supplementary boil-off test (S-5-1) which used an as-received pressure tube. The objective of this paper is to analyze the results obtained from the simulation of this Boil-Off test using the SMARTT computer code and to examine the effect of hydriding on the thermal and ballooning behaviour of the pressure tube by comparison with the results obtained from test S-5-1. A discussion of the results obtained from this comparison is presented together with an analysis of their application to the analysis of pressure tube behaviour in CANDU reactors. (author). 13 refs., 1 tab., 16 figs

  9. Diazotrophic Bacterial Community of Degraded Pastures

    Directory of Open Access Journals (Sweden)

    João Tiago Correia Oliveira

    2017-01-01

    Full Text Available Pasture degradation can cause changes in diazotrophic bacterial communities. Thus, this study aimed to evaluate the culturable and total diazotrophic bacterial community, associated with regions of the rhizosphere and roots of Brachiaria decumbens Stapf. pastures in different stages of degradation. Samples of roots and rhizospheric soil were collected from slightly, partially, and highly degraded pastures. McCrady’s table was used to obtain the Most Probable Number (MPN of bacteria per gram of sample, in order to determine population density and calculate the Shannon-Weaver diversity index. The diversity of total diazotrophic bacterial community was determined by the technique of Denaturing Gradient Gel Electrophoresis (DGGE of the nifH gene, while the diversity of the culturable diazotrophic bacteria was determined by the Polymerase Chain Reaction (BOX-PCR technique. The increase in the degradation stage of the B. decumbens Stapf. pasture did not reduce the population density of the cultivated diazotrophic bacterial community, suggesting that the degradation at any degree of severity was highly harmful to the bacteria. The structure of the total diazotrophic bacterial community associated with B. decumbens Stapf. was altered by the pasture degradation stage, suggesting a high adaptive capacity of the bacteria to altered environments.

  10. Photochemical degradation of alachlor in water

    Directory of Open Access Journals (Sweden)

    Tajana Đurkić

    2017-01-01

    Full Text Available This study investigates the photochemical degradation of alachlor, a chloroacetanilide herbicide. All experiments were conducted in ultra-pure deionized water (ASTM Type I quality using direct ultraviolet (UV photolysis and the UV/H2O2 advanced oxidation process. The direct UV photolysis and UV/H2O2 experiments were conducted in a commercial photochemical reactor with a quartz reaction vessel equipped with a 253.7 nm UV low pressure mercury lamp (Philips TUV 16 W. The experimental results demonstrate that UV photolysis was very effective for alachlor degradation (up to 97% removal using a high UV fluence of 4200 mJ/cm2. The UV/H2O2 process promoted alachlor degradation compared to UV photolysis alone, with a high degree of decomposition (97% achieved at a significantly lower UV fluence of 600 mJ/cm2 when combined with 1 mg H2O2/L. The application of UV photolysis alone with a UV fluence of 600 mJ/cm2 gave a negligible 4% alachlor degradation. The photo degradation of alachlor, in both direct UV photolysis and the UV/H2O2 process, followed pseudo first-order kinetics. The degradation rate constant was about 6 times higher for the UV/H2O2 process than for UV photolysis alone.

  11. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Organic matter degradation in Chilean sediments - following nature's own degradation experiment

    DEFF Research Database (Denmark)

    Langerhuus, Alice Thoft; Niggemann, Jutta; Lomstein, Bente Aagaard

    ORGANIC MATTER DEGRADATION IN CHILEAN SEDIMENTS – FOLLOWING NATURE’S OWN DEGRADATION EXPERIMENT Degradation of sedimentary organic matter was studied at two stations from the shelf of the Chilean upwelling region. Sediment cores were taken at 1200 m and 800 m water depth and were 4.5 m and 7.5 m...... in length, respectively. The objective of this study was to assess the degradability of the organic matter from the sediment surface to the deep sediments. This was done by analysing amino acids (both L- and D-isomers) and amino sugars in the sediment cores, covering a timescale of 15.000 years. Diagenetic...... indicators (percentage of carbon and nitrogen present as amino acid carbon and nitrogen, the ratio between a protein precursor and its non-protein degradation product and the percentage of D-amino acids) revealed ongoing degradation in these sediments, indicating that microorganisms were still active in 15...

  13. Degradation of morpholine by Mycobacterium sp. isolated from ...

    African Journals Online (AJOL)

    Jane

    2011-08-08

    Aug 8, 2011 ... Full Length Research Paper. Degradation ... The heterocyclic xenobiotic compound morpholine (1- ... Culture of morpholine degrading microorganisms ..... Biodegradation and toxicity of selected amines on aquatic organisms.

  14. 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

    2017-07-01

    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 (k obs ) 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 (HCO 3 - 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 SO 4 • - 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. Copyright © 2017. Published by Elsevier Inc.

  15. Nanobiocatalytic Degradation of Acid Orange 7

    Science.gov (United States)

    Hastings, Jason

    The catalytic properties of various metal nanoparticles have led to their use in environmental remediation applications. However, these remediation strategies are limited by their ability to deliver catalytic nanoparticles and a suitable electron donor to large treatment zones. Clostridium pasteurianum BC1 cells, loaded with bio-Pd nanoparticles, were used to effectively catalyze the reductive degradation and removal of Acid Orange 7 (AO7), a model azo compound. Hydrogen produced fermentatively by the C. pasteurianum BC1 acted as the electron donor for the process. Pd-free bacterial cultures or control experiments conducted with heat-killed cells showed limited reduction of AO7. Experiments also showed that the in situ biological production of H2 by C. pasteurianum BC1 was essential for the degradation of AO7, which suggests a novel process where the in situ microbial production of hydrogen is directly coupled to the catalytic bio-Pd mediated reduction of AO7. The differences in initial degradation rate for experiments conducted using catalyst concentrations of 1ppm Pd and 5ppm Pd and an azo dye concentration of 100ppm AO7 was 0.39 /hr and 1.94 /hr respectively, demonstrating the importance of higher concentrations of active Pd(0). The degradation of AO7 was quick as demonstrated by complete reductive degradation of 50ppm AO7 in 2 hours in experiments conducted using a catalyst concentration of 5ppm Pd. Dye degradation products were analyzed via Gas Chromatograph-Mass Spectrometer (GCMS), High Performance Liquid Chromatography (HPLC), UltraViolet-Visible spectrophotometer (UV-Vis) and Matrix-Assisted Laser Desorption/Ionization (MALDI) spectrometry. The presence of 1-amino 2-naphthol, one of the hypothesized degradation products, was confirmed using mass spectrometry.

  16. Mineral induced mechanochemical degradation: the imazaquin case.

    Science.gov (United States)

    Nasser, Ahmed; Buchanovsky, Nadia; Gerstl, Zev; Mingelgrin, Uri

    2009-03-01

    The potential role of mechanochemical processes in enhancing degradation of imazaquin by soil components is demonstrated. The investigated components include montmorillonite saturated with Na(+), Ca(2+), Cu(2+)and Al(3+), Agsorb (a commercial clay mix), birnessite and hematite. The mechanical force applied was manual grinding of mixtures of imazaquin and the minerals, using mortar and pestle. The degradation rates of imazaquin in these mixtures were examined as a function of the following parameters: time of grinding, herbicide load (3.9, 8.9, 16.7 and 26.6 mg imazaquin per g mineral), temperature (10, 25, 40 and 70 degrees C), acidic/basic conditions, and dry or wet grinding. Dry grinding of imazaquin for 5 min with Al-montmorillonite or with hematite resulted in 56% and 71% degradation of the imazaquin, respectively. Wet grinding slightly reduced the degradation rate with hematite and entirely cancelled the enhancing effect of grinding with Al-montmorillonite. Wet grinding in the presence of the transition metals: Ni(2+), Cu(2+), Fe(3+) added as chlorides was carried out. Addition of Cu(2+) to Na-montmorillonite loaded with imazaquin was the most effective treatment in degrading imazaquin (more than 90% of the imazaquin degraded after 5 min of grinding). In this treatment, Cu-montmorillonite formation during the grinding process was confirmed by XRD and accordingly, grinding with Cu-montmorillonite gave similar degradation values. LC-MS analysis revealed that the mechanochemical transformation of imazaquin resulted in the formation of a dimer and several breakdown products. The reported results demonstrate once again that mechanochemical procedures offer a remediation avenue applicable to soils polluted with organic contaminants.

  17. Plugging criteria for steam generator tubes with axial cracks near tube support plates

    International Nuclear Information System (INIS)

    Mattar Neto, Miguel

    2000-01-01

    Stress corrosion cracking with intergranular attack occurs on the secondary side of steam generator (SG) tubes where impurities concentrate due to boiling under restricted flow conditions. In the most of cases, it can be called ODSCC (Outer Diameter Stress Corrosion Cracking). The typical locations are areas near support plates, in sludge piles and at top of tubesheet crevices. Though it can also occur on free spans under the relatively thin deposits that build up on the tube surfaces. ODSCC near tube plate supports have been the cause of plugging of many tubes. Thus, studies on SG tubes plugging criteria related to this degradation mechanism are presented in this paper. Th purpose is to avoid unnecessary tube plugging from either safety or reliability standpoint. Based on these studies some conclusions on the plugging criteria and on the difficulties to apply them are addressed. (author)

  18. Crater Degradation on Mercury: A Global Perspective

    Science.gov (United States)

    Kinczyk, M. J.; Byrne, P. K.; Prockter, L. M.; Susorney, H. C. M.; Chapman, C. R.; Barnouin, O. S.

    2017-12-01

    On geologic timescales, initially fresh craters are subjected to many weathering mechanisms. Whereas water and wind are, or were, effective erosive mechanisms such as on Earth and Mars, micrometeorite bombardment and modification due to subsequent impacts are the dominant processes that degrade craters and crater rays on airless bodies like the Moon and Mercury. Classifying craters based on their state of degradation can help determine the relative ages of landforms proximal to, and crosscut by, these craters. However, this method is most effective when used together with statistical analysis of crater distributions. Pre-MESSENGER degradation classification schemes lacked sufficient detail to be consistently applied to craters of various sizes and morphological types—despite evidence suggesting that the ejecta deposits of large basins persist much longer than those of smaller craters, for instance—yet broad assumptions have been made regarding the correlation of crater class to the planet's time-stratigraphic sequence. Moreover, previous efforts to categorize craters by degradation state have either been restricted to regional study sites or applied only to a subset of crater age or size. As a result, numerous interpretations of crater degradation state persist for Mercury, challenging a complete understanding of this process on the innermost planet. We report on the first global survey of crater degradation on Mercury. By modifying an established 5-class scheme, we have systematically applied a rigorous set of criteria to all craters ≥40 km in diameter on the planet. These criteria include the state and morphology of crater deposits separately (e.g., rim, floor, wall, ejecta) and degradation classes were assigned as the collection of these individual attributes. This approach yields a consistent classification of craters of different sizes. Our results provide the first comprehensive assessment of how craters of various states of degradation are distributed

  19. 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

  20. Phenomenology of BWR fuel assembly degradation

    Science.gov (United States)

    Kurata, Masaki; Barrachin, Marc; Haste, Tim; Steinbrueck, Martin

    2018-03-01

    Severe accidents occurred at the Fukushima-Daiichi Nuclear Power Station (FDNPS) which required an immediate re-examination of fuel degradation phenomenology. The present paper reviews the updated knowledge on the phenomenology of the fuel degradation, focusing mainly on the BWR fuel assembly degradation at the macroscopic scale and that of the individual interactions at the meso-scale. Oxidation of boron carbide (B4C) control rods potentially generates far larger amounts of heat and hydrogen under BWR accident conditions. All integral tests with B4C control rods or control blades have shown early failure, liquefaction, relocation and oxidation of B4C starting at temperatures around 1250 °C, well below the significant interaction temperatures of UO2-Zry. These interactions or reactions potentially influence the progress of fuel degradation in the early phase. The steam-starved conditions, which are being discussed as a likely scenario at the FDNPS accident, highly influence the individual interactions and potentially lead the fuel degradation in non-prototypical directions. The detailed phenomenology of individual interactions and their influence on the transient and on the late phase of the severe accidents are also discussed.

  1. Modeling the degradation kinetics of ascorbic acid.

    Science.gov (United States)

    Peleg, Micha; Normand, Mark D; Dixon, William R; Goulette, Timothy R

    2018-06-13

    Most published reports on ascorbic acid (AA) degradation during food storage and heat preservation suggest that it follows first-order kinetics. Deviations from this pattern include Weibullian decay, and exponential drop approaching finite nonzero retention. Almost invariably, the degradation rate constant's temperature-dependence followed the Arrhenius equation, and hence the simpler exponential model too. A formula and freely downloadable interactive Wolfram Demonstration to convert the Arrhenius model's energy of activation, E a , to the exponential model's c parameter, or vice versa, are provided. The AA's isothermal and non-isothermal degradation can be simulated with freely downloadable interactive Wolfram Demonstrations in which the model's parameters can be entered and modified by moving sliders on the screen. Where the degradation is known a priori to follow first or other fixed order kinetics, one can use the endpoints method, and in principle the successive points method too, to estimate the reaction's kinetic parameters from considerably fewer AA concentration determinations than in the traditional manner. Freeware to do the calculations by either method has been recently made available on the Internet. Once obtained in this way, the kinetic parameters can be used to reconstruct the entire degradation curves and predict those at different temperature profiles, isothermal or dynamic. Comparison of the predicted concentration ratios with experimental ones offers a way to validate or refute the kinetic model and the assumptions on which it is based.

  2. 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.

  3. Degradation of chlorpyrifos in tropical rice soils.

    Science.gov (United States)

    Das, Subhasis; Adhya, Tapan K

    2015-04-01

    Chlorpyrifos [O,O-diethyl O-(3,5,6-trichloro-2-pyridinol) phosphorothioate] is used worldwide as an agricultural insecticide against a broad spectrum of insect pests of economically important crops including rice, and soil application to control termites. The insecticide mostly undergoes hydrolysis to diethyl thiophosphoric acid (DETP) and 3,5,6-trichloro-2-pyridinol (TCP), and negligible amounts of other intermediate products. In a laboratory-cum-greenhouse study, chlorpyrifos, applied at a rate of 10 mg kg(-1) soil to five tropical rice soils of wide physico-chemical variability, degraded with a half-life ranging from 27.07 to 3.82 days. TCP was the major metabolite under both non-flooded and flooded conditions. Chlorpyrifos degradation had significant negative relationship with electrical conductivity (EC), cation exchange capacity (CEC), clay and sand contents of the soils under non-flooded conditions. Results indicate that degradation of chlorpyrifos was accelerated with increase in its application frequency, across the representative rice soils. Management regimes including moisture content and presence or absence of rice plants also influenced the process. Biotic factors also play an important role in the degradation of chlorpyrifos as demonstrated by its convincing degradation in mineral salts medium inoculated with non-sterile soil suspension. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Constitutive and ligand-induced TCR degradation

    DEFF Research Database (Denmark)

    von Essen, Marina; Bonefeld, Charlotte Menné; Siersma, Volkert

    2004-01-01

    Modulation of TCR expression levels is a central event during T cell development and activation, and it probably plays an important role in adjusting T cell responsiveness. Conflicting data have been published on down-regulation and degradation rates of the individual TCR subunits, and several di...... to the lysosomes. Similar results were obtained in studies of primary human Vbeta8+ T cells stimulated with superantigen. Based on these results, the simplest model for TCR internalization, sorting, and degradation is proposed.......Modulation of TCR expression levels is a central event during T cell development and activation, and it probably plays an important role in adjusting T cell responsiveness. Conflicting data have been published on down-regulation and degradation rates of the individual TCR subunits, and several...... divergent models for TCR down-regulation and degradation have been suggested. The aims of this study were to determine the rate constants for constitutive and ligand-induced TCR degradation and to determine whether the TCR subunits segregate or are processed as an intact unit during TCR down...

  5. Individual differneces in degraded speech perception

    Science.gov (United States)

    Carbonell, Kathy M.

    One of the lasting concerns in audiology is the unexplained individual differences in speech perception performance even for individuals with similar audiograms. One proposal is that there are cognitive/perceptual individual differences underlying this vulnerability and that these differences are present in normal hearing (NH) individuals but do not reveal themselves in studies that use clear speech produced in quiet (because of a ceiling effect). However, previous studies have failed to uncover cognitive/perceptual variables that explain much of the variance in NH performance on more challenging degraded speech tasks. This lack of strong correlations may be due to either examining the wrong measures (e.g., working memory capacity) or to there being no reliable differences in degraded speech performance in NH listeners (i.e., variability in performance is due to measurement noise). The proposed project has 3 aims; the first, is to establish whether there are reliable individual differences in degraded speech performance for NH listeners that are sustained both across degradation types (speech in noise, compressed speech, noise-vocoded speech) and across multiple testing sessions. The second aim is to establish whether there are reliable differences in NH listeners' ability to adapt their phonetic categories based on short-term statistics both across tasks and across sessions; and finally, to determine whether performance on degraded speech perception tasks are correlated with performance on phonetic adaptability tasks, thus establishing a possible explanatory variable for individual differences in speech perception for NH and hearing impaired listeners.

  6. Degradation of textile dyes by cyanobacteria.

    Science.gov (United States)

    Dellamatrice, Priscila Maria; Silva-Stenico, Maria Estela; Moraes, Luiz Alberto Beraldo de; Fiore, Marli Fátima; Monteiro, Regina Teresa Rosim

    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. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  7. Seepage into drifts with mechanical degradation

    International Nuclear Information System (INIS)

    Li, Guomin; Tsang, Chin-Fu

    2002-01-01

    Seepage into drifts in unsaturated tuff is an important issue for the long-term performance of the potential nuclear waste repository at Yucca Mountain, Nevada. Drifts in which waste packages will potentially be emplaced are subject to degradation in the form of rockfall from the drift ceiling induced by stress relief, seismic, or thermal effects. The objective of this study is to calculate seepage rates for various drift-degradation scenarios and for different values of percolation flux for the Topopah Spring middle nonlithophysal (Tptpmn) and the Topopah Spring lower lithophysal (Tptpll) units. Seepage calculations are conducted by (1) defining a heterogeneous permeability model on the drift scale that is consistent with field data, (2) selecting calibrated parameters associated with the Tptpmn and Tptpll units, and (3) simulating seepage on detailed degraded-drift profiles, which were obtained from a separate rock mechanics engineering analysis. The simulation results indicate (1) that the seepage threshold (i.e., the percolation flux at which seepage first occurs) is not significantly changed by drift degradation, and (2) the degradation-induced increase in seepage above the threshold is influenced more by the shape of the cavity created by rockfall than the rockfall volume

  8. Material degradation - a nuclear utility's view

    International Nuclear Information System (INIS)

    Spekkens, P.

    2007-01-01

    Degradation of nuclear plant materials has been responsible for major costs and unit outage time. As such, nuclear utilities are important end users of the information produced by R and D on material degradation. This plenary describes the significance of material degradation for the nuclear utilities, and how utilities use information about material degradation in their short, medium and long term planning activities. Utilities invest in R and D programs to assist them in their business objective of operating safely, reliably and cost competitively. Material degradation impacts all three of these business drivers. Utilities make decisions on life cycle planning, unit refurbishment and 'new build' projects on the basis of their understanding of the behaviour of a variety of materials in a broad range of environments. The R and D being carried out today will determine the future business success of the nuclear utilities. The R and D program needs to be broadly based to include a range of materials, environments and time-frames, particularly any new materials proposed for use in new units. The R and D community needs to help the utility managers make choices that will result in an optimized materials R and D program

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

    International Nuclear Information System (INIS)

    Yousaf, Sohail; Afzal, Muhammad; Reichenauer, Thomas G.; Brady, Carrie L.; Sessitsch, Angela

    2011-01-01

    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. Characterization and degradation potential of diesel-degrading bacterial strains for application in bioremediation.

    Science.gov (United States)

    Balseiro-Romero, María; Gkorezis, Panagiotis; Kidd, Petra S; Van Hamme, Jonathan; Weyens, Nele; Monterroso, Carmen; Vangronsveld, Jaco

    2017-10-03

    Bioremediation of polluted soils is a promising technique with low environmental impact, which uses soil organisms to degrade soil contaminants. In this study, 19 bacterial strains isolated from a diesel-contaminated soil were screened for their diesel-degrading potential, biosurfactant (BS) production, and biofilm formation abilities, all desirable characteristics when selecting strains for re-inoculation into hydrocarbon-contaminated soils. Diesel-degradation rates were determined in vitro in minimal medium with diesel as the sole carbon source. The capacity to degrade diesel range organics (DROs) of strains SPG23 (Arthobacter sp.) and PF1 (Acinetobacter oleivorans) reached 17-26% of total DROs after 10 days, and 90% for strain GK2 (Acinetobacter calcoaceticus). The amount and rate of alkane degradation decreased significantly with increasing carbon number for strains SPG23 and PF1. Strain GK2, which produced BSs and biofilms, exhibited a greater extent, and faster rate of alkane degradation compared to SPG23 and PF1. Based on the outcomes of degradation experiments, in addition to BS production, biofilm formation capacities, and previous genome characterizations, strain GK2 is a promising candidate for microbial-assisted phytoremediation of diesel-contaminated soils. These results are of particular interest to select suitable strains for bioremediation, not only presenting high diesel-degradation rates, but also other characteristics which could improve rhizosphere colonization.

  11. 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.

  12. Degradation of hydrocarbons in arctic areas

    International Nuclear Information System (INIS)

    Hundahl Pedersen, M.; Grau-Hansen, B.; Watson Nielsen, T.; Jensen, L.

    1999-12-01

    The scope of this project is to examine the natural degradation of a hydrocarbon contamination by investigating a specific location. The investigated location is a former airfield at Marraq situated on the west coast of Greenland, approx. 90 km south of Nuuk. In Autumn 1942 the US Air force established a diversion airfield called 'Teague Airfield' - under the military code name Bluie West-4. However, the location was abandoned in 1948 and accordingly all facilities and equipment were left behind, among these were a large amount of oil barrels, which mainly contained gas oil. In relation to the present investigation a number of disposal sites were found each containing approx. 50-600 oil barrels of 200 litres each. Through the years these barrels have corroded causing a heavy gas oil contamination several places on the site. This contamination is estimated to have taken place for approx. 40-50 years ago. The contamination is of such a severe character that a heavy smell of oil can be determined on site. Furthermore, vegetation mortality was observed around the barrels in connection to disposal sites situated in places covered by plants. Marraq is a peninsula consisting of coarse fluviatile deposits. The geology is relatively homogeneous without permafrost, which combined with a range of local defined contaminations, provide a unique possibility to assess the controlling environmental factors of natural degradation of oil contamination in the Arctic. A conservative estimate of the complete amount of gas oil which has contaminated the location is estimated to approx. 120,000 litres or more. The investigation showed that the extent of the oil degradation was different at the individual deposit sites. Roughly estimated the contamination is degraded on the order of 15 to twice the original oil amount. Assumable the contamination has been degraded due to the weathering process (evaporation and wash-out) and microbial degradation. Complex processes are involved depending

  13. 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.

  14. Core degradation and fission product release

    International Nuclear Information System (INIS)

    Wright, R.W.; Hagen, S.J.L.

    1992-01-01

    Experiments on core degradation and melt progression in severe LWR accidents have provided reasonable understanding of the principal processes involved in the early phase of melt progression that extends through core degradation and metallic material melting and relocation. A general but not a quantitative understanding of late phase melt progression that involves ceramic material melting and relocation has also been obtained, primarily from the TMI-2 core examination. A summary is given of the current state of knowledge on core degradation and melt progression obtained from these integral experiments and of the principal remaining significant uncertainties. A summary is also given of the principal results on in-vessel fission product release obtained from these experiments. (author). 8 refs, 5 figs, 3 tabs

  15. Isolation and characterization of phenol degrading yeast.

    Science.gov (United States)

    Patel, Riddhi; Rajkumar, Shalini

    2009-04-01

    A phenol degrading yeast isolate was identified and characterized from the soil sample collected from a landfill site, in Ahmedabad, India, by plating the soil dilutions on Sabouraud's Dextrose Agar. The microscopic studies and biochemical tests indicated the isolate to be Saccharomyces cerevisiae. The phenol degrading potential of the isolate was measured by inoculation of pure culture in the mineral medium containing various phenol concentrations ranging from 100 to 800 mg l(-1 )and monitoring phenol disappearance rate at regular intervals of time. Growth of the isolate in mineral medium with various phenol concentrations was monitored by measuring the turbidity (OD(600) nm). The results showed that the isolated yeast was tolerant to phenol up to 800 mg(-1). The phenol degradation ranged from 8.57 to 100% for the concentration of phenol from 800 mg l(-1 )to 200 mg l(-1), respectively. ((c) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).

  16. Degradation of polycarbonate induced by gamma radiation

    International Nuclear Information System (INIS)

    Araujo, E.S. de; Guedes, S.M.L.

    1992-01-01

    Polycarbonate (PC) DUROLON amorphous, of molecular weight 22000 g/mol is used in medical supplies and may be sterilized by gamma radiation. The main chain scission and polymer degradation occur when this polymer is irradiated. The value G = 1.54 to DUROLON was obtained by equation: 10 6 /M v = 10 6 /M v' + 0.054 G R. The degradation without crosslinking it is not general rule to all types of polycarbonates; an comparison was realized. The infrared (FT-IR) spectra of irradiated PC by gamma rays with different doses showed the main chain scissions in carbonyl groups. The mechanism of polymeric degradation to DUROLON, observed by NMR spectra, is a recombination of phenoxy and phenyl radicals. (author)

  17. Degradation monitoring in IRIS steam generators

    International Nuclear Information System (INIS)

    Alpay, B.; Holloway, J. P.; Lee, J. C.

    2007-01-01

    We present a degradation monitoring technique based on unscented Kalman filtering (UKF), which uses a nonlinear system model without linearization to estimate the status of the component/state variables. To test the applicability of the methodology, the fouling of tubes is chosen among various degradation mechanisms for the IRIS (International Reactor Innovative and Secure) steam generators (SGs). The degradation monitoring algorithm diagnoses the tube fouling and estimates the thickness of the crud deposited on the secondary side of the SG along with the increase in the pressure drop triggered by fouling. A stand-alone SG model developed with the RELAP5 code was used to simulate the transient behavior of the SG and drive an UKF state estimate. By using the secondary side outlet temperature as the measurement and the nodal pressures along the secondary side as states, UKF generated accurate estimates of the crud layer thicknesses for different crud formations. (authors)

  18. Degradation of sulfur dioxide using plasma technology

    International Nuclear Information System (INIS)

    Estrada M, N.; Garcia E, R.; Pacheco P, M.; Valdivia B, R.; Pacheco S, J.

    2013-01-01

    This paper presents the electro-chemical study performed for sulfur dioxide (SO 2 ) treatment using non thermal plasma coupled to a nano structured fluid bed enhancing the toxic gas removal and the adsorption of acids formed during plasma treatment, more of 80% of removal was obtained. Non thermal plasma was ignited by dielectric barrier discharge (Dbd). The research was developed through an analysis of the chemical kinetics of the process and experimental study of degradation; in each experiment the electrical parameters and the influence of carbon nano structures were monitored to establish the optimal conditions of degradation. We compared the theoretical and experimental results to conclude whether the proposed model is correct for degradation. (Author)

  19. 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.

  20. The Need for Consensus and Transparency in Assessing Population-Based Rates of Positive Circumferential Radial Margins in Rectal Cancer: Data from Consecutive Cases in a Large Region of Ontario, Canada.

    Science.gov (United States)

    Keng, Christine; Coates, Angela; Grubac, Vanja; Lovrics, Peter; DeNardi, Franco; Thabane, Lehana; Simunovic, Marko

    2016-02-01

    A positive circumferential radial margin (CRM) after rectal cancer surgery is an important predictor of local recurrence. The definition of a positive CRM differs internationally, and reported rates vary greatly in the literature. This study used time-series population-based data to assess positive CRM rates in a region over time and to inform future methods of CRM analysis in a defined geographic area. Chart reviews provided relevant data from consecutive patients undergoing rectal cancer surgery between 2006 and 2012 in all hospitals of the authors' region. Outcomes included rates for pathologic examination of CRM, CRM distance reporting, and positive CRM. The rate of positive CRM was calculated using various definitions. The variations included positive margin cutoffs of CRM at 1 mm or less versus 2 mm or less and inclusion or exclusion of cases without CRM assessment. In this study, 1222 consecutive rectal cancer cases were analyzed. The rate for pathology reporting of CRM distance increased from 54.7 to 93.2 % during the study. Depending on how the rate of positive CRM was defined, its value varied 8.5 to 19.4 % in 2006 and 6.0 to 12.5 % in 2012. Using a pre-specified definition, the rate of positive CRM decreased over time from 14.0 to 6.3 %. A marked increase in CRM distance reporting was observed, whereas the rates of positive CRM dropped, suggesting improved pathologist and surgeon performance over time. Changing definitions greatly influenced the rates of positive CRM, indicating the need for more transparency when such population-based rates are reported in the literature.

  1. Study on the degradation of chitosan slurries

    Directory of Open Access Journals (Sweden)

    Benjamin Martini

    2016-01-01

    Full Text Available In the present work, we measured the degradation rate of different chitosan slurries. Several parameters were monitored such as temperature (25 °C, 37 °C, 50 °C; chitosan concentration (1% and 2% (w/V; and polymer molecular weight. The samples were tested in dynamic sweep test mode. This test is able to provide a reliable estimation of viscosity variations of the slurries; in turn, these variations could be related to degradation rate of the system in the considered conditions. The resulting information is particularly important especially in applications in which there is a close relationship between physical properties and molecular structure.

  2. DSNF AND OTHER WASTE FORM DEGRADATION ABSTRACTION

    International Nuclear Information System (INIS)

    CUNNANE, J.

    2004-01-01

    Several hundred distinct types of DOE-owned spent nuclear fuel (DSNF) may potentially be disposed in the Yucca Mountain repository. These fuel types represent many more types than can be viably individually examined for their effect on the Total System Performance Assessment for the License Application (TSPA-LA). Additionally, for most of these fuel types, there is no known direct experimental test data for the degradation and dissolution of the waste form in repository groundwaters. The approach used in the TSPA-LA model is, therefore, to assess available information on each of 11 groups of DSNF, and to identify a model that can be used in the TSPA-LA model without differentiating between individual codisposal waste packages containing different DSNF types. The purpose of this report is to examine the available data and information concerning the dissolution kinetics of DSNF matrices for the purpose of abstracting a degradation model suitable for use in describing degradation of the DSNF inventory in the Total System Performance Assessment for the License Application. The data and information and associated degradation models were examined for the following types of DSNF: Group 1--Naval spent nuclear fuel; Group 2--Plutonium/uranium alloy (Fermi 1 SNF); Group 3--Plutonium/uranium carbide (Fast Flux Test Facility-Test Fuel Assembly SNF); Group 4--Mixed oxide and plutonium oxide (Fast Flux Test Facility-Demonstration Fuel Assembly/Fast Flux Test Facility-Test Demonstration Fuel Assembly SNF); Group 5--Thorium/uranium carbide (Fort St. Vrain SNF); Group 6--Thorium/uranium oxide (Shippingport light water breeder reactor SNF); Group 7--Uranium metal (N Reactor SNF); Group 8--Uranium oxide (Three Mile Island-2 core debris); Group 9--Aluminum-based SNF (Foreign Research Reactor SNF); Group 10--Miscellaneous Fuel; and Group 11--Uranium-zirconium hydride (Training Research Isotopes-General Atomics SNF). The analyses contained in this document provide an ''upper-limit'' (i

  3. Photo catalytic degradation of m-cresol

    International Nuclear Information System (INIS)

    Chavarria C, N.; Jimenez B, J.; Garcia S, I.; Valenzuela, M.A.

    2002-01-01

    The degradation of m-cresol was studied, a persistent organic compound that is consider a pollutant of residual water. There for a photo catalysis system was used, which consists in a glass reactor where is placed an aqueous solution of m-cresol and a semiconductor is added, in this case, titanium oxide. The solutions were irradiated with ultraviolet light and the surplus m-cresol was measured by UV vis spectrometry. The results indicate that the m-cresol is degraded until a 40% after 5 hours of irradiation in such conditions. (Author)

  4. 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.

  5. Degradation of cellulosic substances by Thermomonospora curvata

    Energy Technology Data Exchange (ETDEWEB)

    Stutzenberger, F J

    1979-05-01

    Research is reported on the cellulolytic activity of Thermomonospora curvata, a thermophilic cellulolytic actinomycete prevalent in municipal solid waste compost. Various cellulosic wastes were evaluated for their potential for the induction of cellulase synthesis by Th. curvata and the extent of cellulose degradation under optimal culture conditions. All the substrates tested showed significant degradation of their cellulose content with the exception of sawdust and barley straw. In contrast to Trichoderma viride, cotton fibers were the best substrates for both C/sub 1/ and C/sub x/ cellulase production. Further research is recommended. (JSR)

  6. A Theoretical Model for Metal Corrosion Degradation

    Directory of Open Access Journals (Sweden)

    David V. Svintradze

    2010-01-01

    Full Text Available Many aluminum and stainless steel alloys contain thin oxide layers on the metal surface which greatly reduce the corrosion rate. Pitting corrosion, a result of localized breakdown of such films, results in accelerated dissolution of the underlying metal through pits. Many researchers have studied pitting corrosion for several decades and the exact governing equation for corrosion pit degradation has not been obtained. In this study, the governing equation for corrosion degradation due to pitting corrosion behavior was derived from solid-state physics and some solutions and simulations are presented and discussed.

  7. Degradation Capability of n-hexadecane Degrading Bacteria from Petroleum Contaminated Soils

    Directory of Open Access Journals (Sweden)

    PENG Huai-li

    2017-05-01

    Full Text Available Samplings were performed in the petroleum contaminated soils of Dongying, Shandong Province of China. Degrading bacteria was isolated through enrichment in a Bushnel-Hass medium, with n-hexadecane as the sole source of carbon and energy. Then the isolated strains were identified by amplification of 16S rDNA gene and sequencing. The strain TZSX2 was selected as the powerful bacteria with stronger degradation ability, which was then identified as Rhodococcus hoagii genera based on the constructing results of the phylogenetic tree. The optimum temperature that allowed both high growth and efficient degradation ratio was in the scope of 28~36 ℃, and gas chromatography results showed that approximately more than 30% of n-hexadecane could be degraded in one week of incubation within the temperature range. Moreover, the strain TZSX2 was able to grow in high concentrations of n-hexadecane. The degradation rate reached 79% when the initial n-hexadecane concentration was 2 mL·L-1,while it still achieved 12% with n-hexadecane concentration of 20 mL·L-1. The optimal pH was 9 that allowed the highest growth and the greatest degradation rate of 91%. Above all, the screened strain TZSX2 showed high capabilities of alkali tolerance with excellent degradation efficiency for even high concentration of n-hexadecane, and thus it would be quite suitable for the remediation of petroleum contaminated soils especially in the extreme environment.

  8. Anthocyanins degradation during storage of Hibiscus sabdariffa extract and evolution of its degradation products.

    Science.gov (United States)

    Sinela, André; Rawat, Nadirah; Mertz, Christian; Achir, Nawel; Fulcrand, Hélène; Dornier, Manuel

    2017-01-01

    Degradation parameters of two main anthocyanins from roselle extract (Hibiscus sabdariffa L.) stored at different temperatures (4-37°C) over 60days were determined. Anthocyanins and some of their degradation products were monitored and quantified using HPLC-MS and DAD. Degradation of anthocyanins followed first-order kinetics and reaction rate constants (k values), which were obtained by non-linear regression, showed that the degradation rate of delphinidin 3-O-sambubioside was higher than that of cyanidin 3-O-sambubioside with k values of 9.2·10(-7)s(-1) and 8.4·10(-7)s(-1) at 37°C respectively. The temperature dependence of the rate of anthocyanin degradation was modeled by the Arrhenius equation. Degradation of delphinidin 3-O-sambubioside (Ea=90kJmol(-1)) tended to be significantly more sensitive to an increase in temperature than cyanidin 3-O-sambubioside (Ea=80kJmol(-1)). Degradation of these anthocyanins formed scission products (gallic and protocatechuic acids respectively) and was accompanied by an increase in polymeric color index. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Cometabolic Degradation of Dibenzofuran and Dibenzothiophene by a Naphthalene-Degrading Comamonas sp. JB.

    Science.gov (United States)

    Ji, Xiangyu; Xu, Jing; Ning, Shuxiang; Li, Nan; Tan, Liang; Shi, Shengnan

    2017-12-01

    Comamonas sp. JB was used to investigate the cometabolic degradation of dibenzofuran (DBF) and dibenzothiophene (DBT) with naphthalene as the primary substrate. Dehydrogenase and ATPase activity of the growing system with the presence of DBF and DBT were decreased when compared to only naphthalene in the growing system, indicating that the presence of DBF and DBT inhibited the metabolic activity of strain JB. The pathways and enzymes involved in the cometabolic degradation were tested. Examination of metabolites elucidated that strain JB cometabolically degraded DBF to 1,2-dihydroxydibenzofuran, subsequently to 2-hydroxy-4-(3'-oxo-3'H-benzofuran-2'-yliden)but-2-enoic acid, and finally to catechol. Meanwhile, strain JB cometabolically degraded DBT to 1,2-dihydroxydibenzothiophene and subsequently to the ring cleavage product. A series of naphthalene-degrading enzymes including naphthalene dioxygenase, 1,2-dihydroxynaphthalene dioxygenase, salicylaldehyde dehydrogenase, salicylate hydroxylase, and catechol 2,3-oxygenase have been detected, confirming that naphthalene was the real inducer of expression the degradation enzymes and metabolic pathways were controlled by naphthalene-degrading enzymes.

  10. Soil Resources Degradation and Conservation Techniques Adopted ...

    African Journals Online (AJOL)

    Soil degradation is increasingly regarded as a major constraint to food production in the tropics. This problem is primarily caused by soil erosion, which particularly damages the soil surfaces. It is therefore the objectives of this paper to study the types of erosion in Gusau area as well as its effects on selected soil properties ...

  11. 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.)

  12. Keratinophilic Fungi: Nature's Keratin Degrading Machines!

    Indian Academy of Sciences (India)

    working on his PhD on taxonomic studies on ..... detected in the culture filtrates, then the fungus does not possess the ability to degrade keratin. .... UK, 1995. [5] Y Graser and others, Medical Mycology, Vol. 31, pp lOS-114, 1999. [6] J Kunert ...

  13. On an orthotropic model for progressive degradation

    DEFF Research Database (Denmark)

    Hammer, Velaja B.; Pedersen, Pauli

    1999-01-01

    Progressive degradation in orthotropic materials is modelled from a smear-out point of view, and physical measurable quantities are used as the describing parameters. Evolution of stiffness and evolution of strength are kept uncoupled. For plane problems the stiffness evolution is modelled...

  14. Electrochemical monitoring of methyl parathion degradation based ...

    African Journals Online (AJOL)

    ... been investigated by using carbon fiber microelectrodes (CFME) as working electrode and acetate buffer pH 5.2 as supporting electrolyte. pnitrophenol (PNP) and p-aminophenol (PAP) recognized as by-products of MP degradation process have been detected and identified in real time using square wave voltammetry.

  15. Digestion and degradation, air for life

    NARCIS (Netherlands)

    Lettinga, G.

    2001-01-01

    Anaerobic degradation of dead biomass is a natural gasification process, an anaerobic crematorium producing a very useful end-product composed of methane and carbon dioxide, generally polluted with small amounts of some malodorous and quite toxic volatile S-compounds. It leads to the production of

  16. Maintenance Operations Degradation of Airfield Pavement Markings

    Science.gov (United States)

    2012-03-01

    DISTRIBUTION STATEMENT A. APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED The views expressed in this article are those of the author and...DISTRIBUTION STATEMENT A. APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED AFIT/GEM/ENV/12-M09 MAINTENANCE OPERATIONS DEGRADATION OF...placement, color, and style (Federal Aviation Adminstration (FAA), 2010). However, regulations and standards do not make good asset management plans

  17. Degradable Adhesives for Surgery and Tissue Engineering.

    Science.gov (United States)

    Bhagat, Vrushali; Becker, Matthew L

    2017-10-09

    This review highlights the research on degradable polymeric tissue adhesives for surgery and tissue engineering. Included are a comprehensive listing of specific uses, advantages, and disadvantages of different adhesive groups. A critical evaluation of challenges affecting the development of next generation materials is also discussed, and insights into the outlook of the field are explored.

  18. Environmental degradation and its relationship with the ...

    African Journals Online (AJOL)

    The results indicated that stress and environmental degradation, contributed significantly to the development of globus pharyngeus; suggesting the need for action in this regard, by governments and relevant governmental agencies saddled with the task of guaranteeing overall public safety and health. Keywords: Globus ...

  19. DSNF AND OTHER WASTE FORM DEGRADATION ABSTRACTION

    International Nuclear Information System (INIS)

    Thornton, T.A.

    2000-01-01

    The purpose of this analysis/model report (AMR) is to select and/or abstract conservative degradation models for DOE-(US. Department of Energy) owned spent nuclear fuel (DSNF) and the immobilized ceramic plutonium (Pu) disposition waste forms for application in the proposed monitored geologic repository (MGR) postclosure Total System Performance Assessment (TSPA). Application of the degradation models abstracted herein for purposes other than TSPA should take into consideration the fact that they are, in general, very conservative. Using these models, the forward reaction rate for the mobilization of radionuclides, as solutes or colloids, away from the waste fondwater interface by contact with repository groundwater can then be calculated. This forward reaction rate generally consists of the dissolution reaction at the surface of spent nuclear fuel (SNF) in contact with water, but the degradation models, in some cases, may also include and account for the physical disintegration of the SNF matrix. The models do not, however, account for retardation, precipitation, or inhibition of the migration of the mobilized radionuclides in the engineered barrier system (EBS). These models are based on the assumption that all components of the DSNF waste form are released congruently with the degradation of the matrix

  20. DSNF and other waste form degradation abstraction

    Energy Technology Data Exchange (ETDEWEB)

    Thornton, Thomas A.

    2000-12-20

    The purpose of this analysis/model report (AMR) is to select and/or abstract conservative degradation models for DOE-(US. Department of Energy) owned spent nuclear fuel (DSNF) and the immobilized ceramic plutonium (Pu) disposition waste forms for application in the proposed monitored geologic repository (MGR) postclosure Total System Performance Assessment (TSPA). Application of the degradation models abstracted herein for purposes other than TSPA should take into consideration the fact that they are, in general, very conservative. Using these models, the forward reaction rate for the mobilization of radionuclides, as solutes or colloids, away from the waste fondwater interface by contact with repository groundwater can then be calculated. This forward reaction rate generally consists of the dissolution reaction at the surface of spent nuclear fuel (SNF) in contact with water, but the degradation models, in some cases, may also include and account for the physical disintegration of the SNF matrix. The models do not, however, account for retardation, precipitation, or inhibition of the migration of the mobilized radionuclides in the engineered barrier system (EBS). These models are based on the assumption that all components of the DSNF waste form are released congruently with the degradation of the matrix.

  1. Land Tenure Induced Deforestation and Environmental Degradation ...

    African Journals Online (AJOL)

    Land Tenure Induced Deforestation and Environmental Degradation in Ethiopia: The Case of Arbagugu State Forest Development and Protection Project (A ... The objective of this paper is to explore the cause and impact of this overarching problem by focusing on Arbagugu State Forest Development and Protection Project, ...

  2. 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.

  3. 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.

  4. Cyanide utilization and degradation by microorganisms.

    Science.gov (United States)

    Knowles, C J

    1988-01-01

    Various microorganisms can produce (cyanogenesis) or degrade cyanide. They degrade cyanide either to detoxify it, or to use it as a source of nitrogen for growth. Significant amounts of cyanide are formed as a secondary metabolite by a wide range of fungi and a few bacteria by decarboxylation of glycine. When cyanide has been formed by the snow mould fungus it is degraded by conversion to carbon dioxide and ammonia via an unknown pathway. In contrast, cyanogenic bacteria either do not further catabolize cyanide or they convert it into beta-cyanoalanine by addition to cysteine or O-acetylserine. Several non-cyanogenic fungi that are pathogens of cyanogenic plants are known to degrade cyanide by hydration to formamide by the enzyme cyanide hydratase. Such fungi can be immobilized and used in packed-cell columns to continuously detoxify cyanide. ICI Biological Products Business market a preparation of spray-dried fungal mycelia, 'CYCLEAR', to detoxify industrial wastes. Novo Industri have also introduced a cyanidase preparation to convert cyanide directly into formate and ammonia. Bacteria have been isolated that use cyanide as a source of nitrogen for growth. Because cyanide, as KCN or NaCN, is toxic for growth, the bacteria (Pseudomonas fluorescens) have to be grown in fed-batch culture with cyanide as the limiting nutrient. Cyanide is converted to carbon dioxide and ammonia (which is then assimilated) by an NADH-linked cyanide oxygenase system.

  5. Soil degradation in Sub-Saharan Africa

    NARCIS (Netherlands)

    Hartemink, A.E.; Keulen, van H.

    2005-01-01

    Soil degradation in Sub-Sahara Africa has been much debated in the past decades. Although there are many different views, at the extremes there are those who are of the opinion that the problem is very serious and the main cause for the poverty and food crises and those that are convinced that it is

  6. Surface degradation of nanocrystalline zirconia dental implants

    NARCIS (Netherlands)

    Ocelík, Václav; Schepke, Ulf; Rasoul, Hamid Haji; Cune, Marco S.; De Hosson, Jeff Th M.

    2017-01-01

    Yttria-stabilized zirconia prepared by hot isostatic pressing represents attractive material for biomedical applications. In this work the degradation of yttria-stabilized zirconia dental implants abutments due to the tetragonal to monoclinic phase transformation after one year of clinical use was

  7. Polyvinyl chloride degradation by X-rays

    International Nuclear Information System (INIS)

    Sbampato, M.E.

    1984-01-01

    Degradation of film samples of pure PVC and comercial film (PVC + Polyacrylatis) with vacuum X-rays using the following techniques: infra-red, Raman, ultra violet and visible spectroscopies, eletronic paramagnetic resonance, X-rays difraction, percent measurement of transmitance and microanalysis was studied. (L.M.J.) [pt

  8. 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

  9. Review: Microbial degradation of toluene | Gopinath | African ...

    African Journals Online (AJOL)

    In spite of positive potential application, toluene results in many mishaps especially health hazards; hence amputation of toluene is crucial for human welfare as well as environmental issues. This review deals with destruction of toluene using microbial degradation. The overall aerobic biodegradation of toluene into carbon ...

  10. Enzymology and molecular biology of lignin degradation

    Science.gov (United States)

    D. Cullen; P.J. Kersten

    2004-01-01

    This review provides an overview of the physiology and genetics of lignin degradation by white rot basidiomycetes. Emphasis is on recent advances and the reader is referred to earlier comprehensive reviews for historical perspective and background (Kirk and Farrell 1987; Gold and Alic 1993; Higuchi 1993; Cullen and Kersten 1996; Cullen 1997). Recent completion of a...

  11. A constitutive law for degrading bioresorbable polymers.

    Science.gov (United States)

    Samami, Hassan; Pan, Jingzhe

    2016-06-01

    This paper presents a constitutive law that predicts the changes in elastic moduli, Poisson's ratio and ultimate tensile strength of bioresorbable polymers due to biodegradation. During biodegradation, long polymer chains are cleaved by hydrolysis reaction. For semi-crystalline polymers, the chain scissions also lead to crystallisation. Treating each scission as a cavity and each new crystal as a solid inclusion, a degrading semi-crystalline polymer can be modelled as a continuum solid containing randomly distributed cavities and crystal inclusions. The effective elastic properties of a degrading polymer are calculated using existing theories for such solid and the tensile strength of the degrading polymer is predicted using scaling relations that were developed for porous materials. The theoretical model for elastic properties and the scaling law for strength form a complete constitutive relation for the degrading polymers. It is shown that the constitutive law can capture the trend of the experimental data in the literature for a range of biodegradable polymers fairly well. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Microbial degradation of textile industrial effluents | Palamthodi ...

    African Journals Online (AJOL)

    Textile waste water is a highly variable mixture of many polluting substance ranging from inorganic compounds and elements to polymers and organic products. To ensure the safety of effluents, proper technologies need to be used for the complete degradation of dyes. Traditionally, treatments of textile waste water involve ...

  13. Factors Influencing Degradation of Mercaptans by Thiobacillus ...

    African Journals Online (AJOL)

    Degradation of methylmercaptans by Thiobacillus thioparus TK-m was influenced by pH of the reaction medium. Ratios of headspace concentrations in empty vials and those of acidified buffer solutions were less than 1.0. 95% of the H2S was in headspace with the remaining 5% in solution upon acidification. The values for ...

  14. Modelling the behaviour of organic degradation products

    International Nuclear Information System (INIS)

    Cross, J.E.; Ewart, F.T.; Greenfield, B.F.

    1989-03-01

    Results are presented from recent studies at Harwell which show that the degradation products which are formed when certain organic waste materials are exposed to the alkaline conditions typical of a cementitious environment, can enhance the solubility of plutonium, even at pH values as high as 12, by significant factors. Characterisation of the degradation products has been undertaken but the solubility enhancement does not appear to be related to the concentration of any of the major organic species that have been identified in the solutions. While it has not been possible to identify by analysis the organic ligand responsible for the increased solubility of plutonium, the behaviour of D-Saccharic acid does approach the behaviour of the degradation products. The PHREEQE code has been used to simulate the solubility of plutonium in the presence of D-Saccharic acid and other model degradation products, in order to explain the solubility enhancement. The extrapolation of the experimental conditions to the repository is the major objective, but in this work the ability of a model to predict the behaviour of plutonium over a range of experimental conditions has been tested. (author)

  15. Plant-Polysaccharide-Degrading Enzymes from Basidiomycetes

    Science.gov (United States)

    Rytioja, Johanna; Hildén, Kristiina; Yuzon, Jennifer; Hatakka, Annele; de Vries, Ronald P.

    2014-01-01

    SUMMARY Basidiomycete fungi subsist on various types of plant material in diverse environments, from living and dead trees and forest litter to crops and grasses and to decaying plant matter in soils. Due to the variation in their natural carbon sources, basidiomycetes have highly varied plant-polysaccharide-degrading capabilities. This topic is not as well studied for basidiomycetes as for ascomycete fungi, which are the main sources of knowledge on fungal plant polysaccharide degradation. Research on plant-biomass-decaying fungi has focused on isolating enzymes for current and future applications, such as for the production of fuels, the food industry, and waste treatment. More recently, genomic studies of basidiomycete fungi have provided a profound view of the plant-biomass-degrading potential of wood-rotting, litter-decomposing, plant-pathogenic, and ectomycorrhizal (ECM) basidiomycetes. This review summarizes the current knowledge on plant polysaccharide depolymerization by basidiomycete species from diverse habitats. In addition, these data are compared to those for the most broadly studied ascomycete genus, Aspergillus, to provide insight into specific features of basidiomycetes with respect to plant polysaccharide degradation. PMID:25428937

  16. Application of radiation degraded carbohydrates for plants

    International Nuclear Information System (INIS)

    Kume, T.; Nagasawa, N.; Yoshu, F.

    1999-01-01

    Radiation degraded carbohydrates such as chitosan, sodium alginate, carageenan, cellulose, pectin, etc. were applied for plant cultivation. Chitosan (poly-β -D-glucosamine) was easily degraded by irradiation and induced various kinds of biological activities such as anti-microbacterial activity, promotion of plant growth, suppression of heavy metal stress on plants, phytoalexins induction, etc. Pectic fragments obtained from degraded pectin also induced the phytoalexins such as glyceollins in soybean and pisafin in pea. The irradiated chitosan shows the higher elicitor activity for pisafin than that of pectin. For the plant growth promotion, alginate derived from brown marine algae, chitosan and ligno-cellulosic extracts show a strong activity. The hot water and ethanol extracts from EFB and sugar cane bagasse were increased by irradiation. These extracts promoted the growth of plants and suppressed the damage on barley with salt and Zn stress. The results show that the degraded polysaccharides by radiation have the potential to induce various biological activities and the products can be use for agricultural and medical fields

  17. Lactose contaminant as steroid degradation enhancer

    NARCIS (Netherlands)

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

    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

  18. Identification and genetic characterization of phenol- degrading ...

    African Journals Online (AJOL)

    SAURABH

    2013-02-20

    Feb 20, 2013 ... this paper, we reported about the new strain of Acinetobacter sp. ... characteristics of an efficient phenol-degrading microorganism. ... compounds are widespread in the environment. The problem is compounded by the fact that phenol is toxic, ... The phenol biodegradation ability of this bacterium was.

  19. Degradation of chitosan for rice crops application

    International Nuclear Information System (INIS)

    Norzita Yacob; Maznah Mahmud; Norhashidah Talip; Kamaruddin Hashim; Abdul Rahim Harun; Khairul Zaman; Hj Dahlan

    2013-01-01

    A variety of techniques including chemical and enzymatic hydrolysis, and radiation degradation processes can be used to prepare low molecular weight chitosan. Degradation of chitosan by radiation can be carried out in solid state and liquid state. Radiation degraded polysaccharides has been reported to exhibit growth-stimulating activity like phytohormones that induce the promotion in germination, shoot and root elongation in variety of plants. In this study, the chitosan was irradiated in solid state (powder form) by gamma rays within the dose range of 25-75 kGy. And the irradiated chitosan was then irradiated in solution form in the presence of hydrogen peroxide. The effects of irradiation on the molecular weight and viscosity of the chitosan were investigated using Ubbelohde Capillary Viscometer. The molecular weight and viscosity of the chitosan decreased with increment of absorbed doses. In the presence of hydrogen peroxide, the molecular weight of chitosan could be further decreased. The effect of radiation degraded chitosan on the growth promotion of rice was investigated and it was shown during seedling period of 15 days for transplanting whereby the growth is 15%-20% faster than using chemicals growth promoters. (authors)

  20. 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