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Sample records for study evaluating mechanical

  1. Evaluating Risk Awareness in Undergraduate Students Studying Mechanical Engineering

    Science.gov (United States)

    Langdon, G. S.; Balchin, K.; Mufamadi, P.

    2010-01-01

    This paper examines the development of risk awareness among undergraduate students studying mechanical engineering at a South African university. A questionnaire developed at the University of Liverpool was modified and used on students from the first, second and third year cohorts to assess their awareness in the areas of professional…

  2. Study on Mechanism Experiments and Evaluation Methods for Water Eutrophication

    Directory of Open Access Journals (Sweden)

    Jiabin Yu

    2017-01-01

    Full Text Available The process of water eutrophication involves the interaction of external factors, nutrients, microorganisms, and other factors. It is complex and has not yet been effectively studied. To examine the formation process of water eutrophication, a set of orthogonal experiments with three factors and four levels is designed to analyze the key factors. At the same time, with the help of a large amount of monitoring data, the principal component analysis method is used to extract the main components of water eutrophication and determine the effective evaluation indicators of eutrophication. Finally, the Bayesian theory of uncertainty is applied to the evaluation of the eutrophication process to evaluate the sample data. The simulation results demonstrate the validity of the research method.

  3. Application of radiobiological techniques in studying antioxidant mechanisms: evaluation of their radioprotective, antioxidative and antiviral activities

    International Nuclear Information System (INIS)

    Hmamouchi, M.

    2000-01-01

    In the medical field, the oxidation phenomenon is the source of several pathologies (diabetes, cystic fibrosis, cancers,...). The natural oxidants are used as food preserving and skin ageing moderators. Several plant extracts with antioxidant activity were studied, this important antioxidant activity is probably due to their richness of compounds: polyphenols, phenolic acids, tocopherols, carotenoids, flavonoids,... Many techniques for evaluation and reactional mechanism study of the antioxidative activity are used. After selection, extraction, fractionation, activity screening, chemical analyses of molecules contained in the best active extracts, biological properties research of isolated redox pharmacophore, we have : - determined the structure of active products by spectroscopy and chromatography; - studied the antioxidative properties by EPR and spin trapping of the obtained extracts and molecules. The results of this first part of our work consists in evaluating the antioxidative degree of a great number of natural active principles, extracted from moroccan plants and pur obtained products. The second part consists in studying the action mechanisms using the LDL labelling (F. M.)

  4. A study on the sound quality evaluation model of mechanical air-cleaners

    DEFF Research Database (Denmark)

    Ih, Jeong-Guon; Jang, Su-Won; Jeong, Cheol-Ho

    2009-01-01

    In operating the air-cleaner for a long time, people in a quiet enclosed space expect low sound at low operational levels for a routine cleaning of air. However, in the condition of high operational levels of the cleaner, a powerful yet nonannoying sound is desired, which is connected to a feeling...... of an immediate cleaning of pollutants. In this context, it is important to evaluate and design the air-cleaner noise to satisfy such contradictory expectations from the customers. In this study, a model for evaluating the sound quality of air-cleaners of mechanical type was developed based on objective...... and subjective analyses. Sound signals from various aircleaners were recorded and they were edited by increasing or decreasing the loudness at three wide specific-loudness bands: 20-400 Hz (0-3.8 barks), 400-1250 Hz (3.8-10 barks), and 1.25- 12.5 kHz bands (10-22.8 barks). Subjective tests using the edited...

  5. A Study on Coexistence Capability Evaluations of the Enhanced Channel Hopping Mechanism in WBANs

    Directory of Open Access Journals (Sweden)

    Zhongcheng Wei

    2017-01-01

    Full Text Available As an important coexistence technology, channel hopping can reduce the interference among Wireless Body Area Networks (WBANs. However, it simultaneously brings some issues, such as energy waste, long latency and communication interruptions, etc. In this paper, we propose an enhanced channel hopping mechanism that allows multiple WBANs coexisted in the same channel. In order to evaluate the coexistence performance, some critical metrics are designed to reflect the possibility of channel conflict. Furthermore, by taking the queuing and non-queuing behaviors into consideration, we present a set of analysis approaches to evaluate the coexistence capability. On the one hand, we present both service-dependent and service-independent analysis models to estimate the number of coexisting WBANs. On the other hand, based on the uniform distribution assumption and the additive property of Possion-stream, we put forward two approximate methods to compute the number of occupied channels. Extensive simulation results demonstrate that our estimation approaches can provide an effective solution for coexistence capability estimation. Moreover, the enhanced channel hopping mechanism can significantly improve the coexistence capability and support a larger arrival rate of WBANs.

  6. A study on the evaluation for dynamic fracture mechanics parameters of viscoelastic materials by impact bending

    International Nuclear Information System (INIS)

    Sim, Jae Ki; Cho, Kyu Jac

    1988-01-01

    In this paper We derived simple formulas for the dynamic strain intensity factor by means of the Timoshenko's beam theory including the influence of rotary inertia and shear deformation on the three-point viscoelastic bend specimen. Also the contact force between the specimen and the impactor is estimated by appling the nonlinear integral equation and the Hertz's theory to the local deformation near the contact point. The results obtained from this study are as follow : 1. Analysis results of this paper, base on Timoshenko's beam theory, were more accuracy than that of Euler-Bernouli beam theory and it can be confirmed by comparsion the results with experimental results. 2. Hertz's contact thepry is static one, but it is proved that by the solution of dynamic strain intensity factor it can be applied for the case of dynamic one. 3. It is founded that the fracture mechanics paraments are overestimatimated if the effects of rotary inertia and transverse shear deformation of specimen are negleted. (Author)

  7. Service user engagement in healthcare education as a mechanism for value based recruitment: An evaluation study.

    Science.gov (United States)

    Heaslip, Vanessa; Scammell, Janet; Mills, Anne; Spriggs, Ashley; Addis, Andrea; Bond, Mandy; Latchford, Carolyn; Warren, Angela; Borwell, Juliet; Tee, Stephen

    2018-01-01

    Within the United Kingdom (UK) there is an increasing focus on Values Based Recruitment (VBR) of staff working in the National Health Service (NHS) in response to public inquiries criticising the lack of person-centred care. All NHS employees are recruited on the basis of a prescribed set of values. This is extended to the recruitment of student healthcare professionals, yet there is little research of how to implement this. Involving Service Users in healthcare educational practice is gaining momentum internationally, yet involvement of service users in VBR of 'would be' healthcare professionals remains at an embryonic phase. Adult nurses represent the largest healthcare workforce in the UK, yet involvement of service users in their recruitment has received scant attention. This paper is an evaluation of the inclusion of service users in a VBR of 640 adult student nurses. This study used a participatory mixed methods approach, with service users as co-researchers in the study. The study consisted of mixed methods design. Quantitative data via an online questionnaire to ascertain candidates' perspectives (n=269 response rate of 42%), and academic/clinical nurses (n=35 response rate 34.65%). Qualitative data were gathered using focus groups and one to one interviews with service users (n=9). Data analysis included descriptive statistics and thematic analysis. 4 overarching themes were identified; increasing sense of humanness, substantiating care values; impact of involvement; working together and making it work, a work in progress. The findings from the study highlight that involving service users in VBR of student healthcare professionals has benefits to candidates, service users and local health services. Appreciating the perceptions of healthcare professionals is fundamental in the UK and internationally to implementing service users' engagement in service enhancement and delivery. Findings from this study identify there may be a dissonance between the policy

  8. A mechanism for revising accreditation standards: a study of the process, resources required and evaluation outcomes.

    Science.gov (United States)

    Greenfield, David; Civil, Mike; Donnison, Andrew; Hogden, Anne; Hinchcliff, Reece; Westbrook, Johanna; Braithwaite, Jeffrey

    2014-11-21

    The study objective was to identify and describe the process, resources and expertise required for the revision of accreditation standards, and report outcomes arising from such activities. Secondary document analysis of materials from an accreditation standards development agency. The Royal Australian College of General Practitioners' (RACGP) documents, minutes and reports related to the revision of the accreditation standards were examined. The RACGP revision of the accreditation standards was conducted over a 12 month period and comprised six phases with multiple tasks, including: review methodology planning; review of the evidence base and each standard; new material development; constructing field trial methodology; drafting, trialling and refining new standards; and production of new standards. Over 100 individuals participated, with an additional 30 providing periodic input and feedback. Participants were drawn from healthcare professional associations, primary healthcare services, accreditation agencies, government agencies and public health organisations. Their expertise spanned: project management; standards development and writing; primary healthcare practice; quality and safety improvement methodologies; accreditation implementation and surveying; and research. The review and development process was shaped by five issues: project expectations; resource and time requirements; a collaborative approach; stakeholder engagement; and the product produced. The RACGP evaluation was that participants were positive about their experience, the standards produced and considered them relevant for the sector. The revision of accreditation standards requires considerable resources and expertise, drawn from a broad range of stakeholders. Collaborative, inclusive processes that engage key stakeholders helps promote greater industry acceptance of the standards.

  9. Mechanisms of repetitive retrograde contractions in response to sustained esophageal distension: a study evaluating patients with postfundoplication dysphagia.

    Science.gov (United States)

    Carlson, Dustin A; Kahrilas, Peter J; Ritter, Katherine; Lin, Zhiyue; Pandolfino, John E

    2018-03-01

    Repetitive retrograde contractions (RRCs) in response to sustained esophageal distension are a distinct contractility pattern observed with functional luminal imaging probe (FLIP) panometry that are common in type III (spastic) achalasia. RRCs are hypothesized to be indicative of either impaired inhibitory innervation or esophageal outflow obstruction. We aimed to apply FLIP panometry to patients with postfundoplication dysphagia (a model of esophageal obstruction) to explore mechanisms behind RRCs. Adult patients with dysphagia after Nissen fundoplication ( n = 32) or type III achalasia ( n = 25) were evaluated with high-resolution manometry (HRM) and upper endoscopy with FLIP. HRM studies were assessed for outflow obstruction and spastic features: premature contractility, hypercontractility, and impaired deglutitive inhibition during multiple-rapid swallows. FLIP studies were analyzed to determine the esophagogastric junction (EGJ)-distensibility index and contractility pattern, including RRCs. Barium esophagram was evaluated when available. RRCs were present in 8/32 (25%) fundoplication and 19/25 (76%) achalasia patients ( P esophageal outflow obstruction, as a predictor for RRCs. RRCs in response to sustained esophageal distension appear to be a manifestation of spastic esophageal motility. Although future study to further clarify the significance of RRCs is needed, RRCs on FLIP panometry should prompt evaluation for a major motor disorder. NEW & NOTEWORTHY Repetitive retrograde contractions (RRCs) are a common response to sustained esophageal distension among spastic achalasia patients when evaluated with the functional luminal imaging probe. We evaluated patients with postfundoplication dysphagia, i.e., patients with suspected mechanical obstruction, and found that RRCs occasionally occurred among postfundoplication patients, but often in association with manometric features of esophageal neuromuscular imbalance. Thus, RRCs appear to be a manifestation of

  10. Evaluation of Mechanical Properties and Morphological Studies of Rice Husk (Treated/Untreated)-CaCO3 Reinforced Epoxy Hybrid Composites

    Science.gov (United States)

    Verma, Deepak; Joshi, Garvit; Gupta, Ayush

    2016-10-01

    Natural fiber reinforced composites are a very popular area of research because of the easy availability and biodegradability of these fibers. The manufacturing of natural fiber composite is done by reinforcing fibers in the particulate form, fiber form or in woven mat form. Natural fiber composites also utilize industrial wastes as a secondary reinforcements like fly ash, sludge etc. By keeping all these point of views in the present investigation the effect of rice husk flour (chemically treated/untreated) and micro sized calcium carbonate with epoxy resin have been evaluated. The diameter of rice husk flour was maintained at 600 µm through mechanical sieving machine. The husk flour was chemically treated with NaOH (5 % w/v). Mechanical properties like hardness, flexural impact and compression strength were evaluated and found to be superior in modified or chemically treated flour as compared to unmodified or untreated flour reinforced composites. Scanning electron microscopy (SEM) study was also undertaken for the developed composites. SEM study shows the distribution of the rice husk flour and calcium carbonate over the matrix.

  11. Synthesis and evaluation of new organic and phosphorous derivatives against ionizing radiation: study of the in vitro mechanism of action

    International Nuclear Information System (INIS)

    Prouillac, C.

    2006-10-01

    This work falls under a research program. The aim was to synthesize new organic phosphorylated compounds having an interesting radio pharmacological activity without toxicity. That is why, we carried out the synthesis of new benzothiazole and thiadiazole N-substituted derivatives as thiols, amino thiols, acids thio-sulfonic and phosphoro thioates. All these compounds were characterized by NMR (proton, carbon, phosphorus, 2D), by mass spectrometry, elementary analyzes and for some of them by diffraction of x-rays. The activity of the majority of them was evaluated by in vitro tests. The experimental results were confirmed by theoretical study: the aim of D.F.T. calculation was the study of the mechanism of capture of the free radicals by our compounds. In addition, a study of relation structure activity (Q.S.A.R.) was carried out. Our results allow us to create a model making it possible to establish structure-activity relationship. (author)

  12. Flow confirmation study for central venous port in oncologic outpatient undergoing chemotherapy: Evaluation of suspected system-related mechanical complications

    International Nuclear Information System (INIS)

    Sofue, Keitaro; Arai, Yasuaki; Takeuchi, Yoshito; Sugimura, Kazuro

    2013-01-01

    Purpose: To evaluate the efficacy and outcome of a flow confirmation study (FCS) in oncologic outpatients undergoing chemotherapy suspected of a central venous port (CVP) system-related mechanical complication. Materials and methods: A total of 66 patients (27 men, 39 women; mean age, 60 years) received FCS for the following reasons: prolonged infusion time during chemotherapy (n = 32), inability to inject saline fluid (n = 15), lateral neck and/or back pain (n = 6), subcutaneous extravasation of anticancer drug (n = 5), arm swelling (n = 4), and inability to puncture the port (n = 4). FCS consisted of examining the position of CVP, potential secondary shifts or fractures, and integrity of the system using contrast material through the port. Results: Of the 66 patients, 43 had an abnormal finding uncovered by FCS. The most frequent abnormal findings was catheter kinking (n = 22). Explantation and reimplantation of the CVP system was required in 21 of the 66 patients. Remaining 45 patients were able continue using the CVP system after the FCS without any system malfunction. Conclusion: FCS was effective for evaluating CVP system-related mechanical complications and was useful for deciding whether CVP system explantation and reimplantation was required

  13. Flow confirmation study for central venous port in oncologic outpatient undergoing chemotherapy: Evaluation of suspected system-related mechanical complications

    Energy Technology Data Exchange (ETDEWEB)

    Sofue, Keitaro, E-mail: ksofue@ncc.go.jp [Divisions of Diagnostic Radiology, National Cancer Center Hospital (Japan); Department of Radiology, Kobe University, Graduate School of Medicine (Japan); Arai, Yasuaki; Takeuchi, Yoshito [Divisions of Diagnostic Radiology, National Cancer Center Hospital (Japan); Sugimura, Kazuro [Department of Radiology, Kobe University, Graduate School of Medicine (Japan)

    2013-11-01

    Purpose: To evaluate the efficacy and outcome of a flow confirmation study (FCS) in oncologic outpatients undergoing chemotherapy suspected of a central venous port (CVP) system-related mechanical complication. Materials and methods: A total of 66 patients (27 men, 39 women; mean age, 60 years) received FCS for the following reasons: prolonged infusion time during chemotherapy (n = 32), inability to inject saline fluid (n = 15), lateral neck and/or back pain (n = 6), subcutaneous extravasation of anticancer drug (n = 5), arm swelling (n = 4), and inability to puncture the port (n = 4). FCS consisted of examining the position of CVP, potential secondary shifts or fractures, and integrity of the system using contrast material through the port. Results: Of the 66 patients, 43 had an abnormal finding uncovered by FCS. The most frequent abnormal findings was catheter kinking (n = 22). Explantation and reimplantation of the CVP system was required in 21 of the 66 patients. Remaining 45 patients were able continue using the CVP system after the FCS without any system malfunction. Conclusion: FCS was effective for evaluating CVP system-related mechanical complications and was useful for deciding whether CVP system explantation and reimplantation was required.

  14. Evaluation of a flexible bronchoscope prototype designed for bronchoscopy during mechanical ventilation: a proof-of-concept study.

    Science.gov (United States)

    Nay, M-A; Auvet, A; Mankikian, J; Herve, V; Dequin, P-F; Guillon, A

    2017-06-01

    Bronchoscopy during mechanical ventilation of patients' lungs significantly affects ventilation because of partial obstruction of the tracheal tube, and may thus be omitted in the most severely ill patients. It has not previously been possible to reduce the external diameter of the bronchoscope without reducing the diameter of the suction channel, thus reducing the suctioning capacity of the device. We believed that a better-designed bronchoscope could improve the safety of bronchoscopy in patients whose lungs were ventilated. We designed a flexible bronchoscope prototype with a drumstick-shaped head consisting of a long, thin proximal portion; a short and large distal portion for camera docking; and a large suction channel throughout the length of the device. The aims of our study were to test the impact of our prototype on mechanical ventilation when inserted into the tracheal tube, and to assess suctioning capacity. We first tested the efficiency of the suction channel, and demonstrated that the suction flow of the prototype was similar to that of conventional adult bronchoscopes. We next evaluated the consequences of bronchoscopy when using the prototype on minute ventilation and intrathoracic pressures during mechanical ventilation: firstly, in vitro using a breathing simulator; and secondly, in vivo using a porcine model of pulmonary ventilation. The insertion of adult bronchoscopes into the tracheal tube immediately impaired the protective ventilation strategy employed, whereas the prototype preserved it. For the first time, we have developed an innovative flexible bronchoscope designed for bronchoscopy during invasive mechanical ventilation, that both preserved the protective ventilation strategy, and enabled efficient suction flow. © 2017 The Association of Anaesthetists of Great Britain and Ireland.

  15. Evaluation of five CAD/CAM materials by microstructural characterization and mechanical tests: a comparative in vitro study.

    Science.gov (United States)

    Sonmez, Nesrin; Gultekin, Pinar; Turp, Volkan; Akgungor, Gokhan; Sen, Deniz; Mijiritsky, Eitan

    2018-01-08

    Polymer infiltrated ceramics and nano-ceramic resins are the new restorative materials which have been developed in order to enhance the adverse properties of glass-matrix ceramics and resin composites. The aim of the present in vitro study was to evaluate the characteristics of various CAD/CAM materials through mechanical, microstructural, and SEM analysis. Five test groups (n = 22) were formed by using the indicated CAD/CAM blocks: VITA Enamic (VITA Zahnfabrik), Lava Ultimate (3 M ESPE), IPS e.max CAD (Ivoclar Vivadent), IPS Empress CAD (Ivoclar Vivadent), and VITA Mark II (VITA Zahnfabrik). Two specimens from each test group were used for XRD and EDS analysis. Remaining samples were divided into two subgroups (n = 10). One subgroup specimens were thermocycled (5 °C to 55 °C, 30s, 10,000 cycles) whereas the other were not. All of the specimens were evaluated in terms of flexural strength, Vickers hardness, and fracture toughness. Results were statistically analyzed using two-way ANOVA, one-way ANOVA, Tukey's HSD, and Student's t tests (α = .05). Fractured specimens were evaluated using SEM. The highest Vickers microhardness value was found for VITA Mark II (p CAD was found to have the highest flexural strength (p CAD was also higher than other tested block materials (p CAD groups. It should be realised that simulated aging process seem to affect ceramic-polymer composite materials more significantly than glass ceramics.

  16. The Evaluation of the Effectiveness of ESP Courses in Enhancing Technical Translation Proficiency: A Case Study of ESP Course for Mechanical Engineering Students

    Science.gov (United States)

    Hatam, Amir Hussein; Shafiei, Shilan

    2012-01-01

    The purpose of the present study was twofold. Firstly, it tried to investigate the relationship between the technical English proficiency of the students of Mechanical Engineering in the universities of Iran and their technical translation proficiency in translating technical texts of Mechanics. Secondly, it attempted to evaluate the effectiveness…

  17. Rock mechanics models evaluation report

    International Nuclear Information System (INIS)

    1987-08-01

    This report documents the evaluation of the thermal and thermomechanical models and codes for repository subsurface design and for design constraint analysis. The evaluation was based on a survey of the thermal and thermomechanical codes and models that are applicable to subsurface design, followed by a Kepner-Tregoe (KT) structured decision analysis of the codes and models. The primary recommendations of the analysis are that the DOT code be used for two-dimensional thermal analysis and that the STEALTH and HEATING 5/6 codes be used for three-dimensional and complicated two-dimensional thermal analysis. STEALTH and SPECTROM 32 are recommended for thermomechanical analyses. The other evaluated codes should be considered for use in certain applications. A separate review of salt creep models indicate that the commonly used exponential time law model is appropriate for use in repository design studies. 38 refs., 1 fig., 7 tabs

  18. Telemedicine Versus Face-to-Face Evaluations by Respiratory Therapists of Mechanically Ventilated Neonates and Children: A Pilot Study.

    Science.gov (United States)

    Bell, Rebecca C; Yager, Phoebe H; Clark, Maureen E; Roumiantsev, Serguei; Venancio, Heather L; Chipman, Daniel W; Kacmarek, Robert M; Noviski, Natan N

    2016-02-01

    Mechanical ventilation is one of the most important therapeutic interventions in neonatal and pediatric ICUs. Telemedicine has been shown to reliably extend pediatric intensivist expertise to facilities where expertise is limited. If reliable, telemedicine may extend the reach of pediatric respiratory therapists (RTs) to facilities where expertise does not exist or free up existing RT resources for important face-to-face activities in facilities where expertise is limited. The aim of this study was to determine how well respiratory assessments for ventilated neonates and children correlated when performed simultaneously by 2 RTs face-to-face and via telemedicine. We conducted a pilot study including 40 assessments by 16 RTs on 11 subjects (5 neonatal ICU; 6 pediatric ICU). Anonymously completed intake forms by 2 different RTs concurrently assessing 14 ventilator-derived and patient-based respiratory variables were used to determine correlations. Forty paired assessments were performed. Median telemedicine assessment time was 8 min. The Pearson correlation coefficient (r) was used to determine agreement between continuous data, and the Cohen kappa statistics were used for binary variables. Pressure control, PEEP, breathing frequency, and FIO2 perfectly correlated (r = 1, all P Telemedicine technology was acceptable to RTs. Telemedicine evaluations highly correlated with face-to-face for 10 of 14 aspects of standard bedside respiratory assessment. Poor correlation was noted for more complex, patient-generated parameters, highlighting the importance of further investigation incorporating a virtual stethoscope. Copyright © 2016 by Daedalus Enterprises.

  19. Study of crotoxin mechanism of action to mammary carcinomas and evaluation of its potential as a radiopharmaceutical

    International Nuclear Information System (INIS)

    Silveira, Marina Bicalho

    2010-01-01

    Crotoxin, the main component of Crotalus durissus terrificus snake venom, has been studied since 1938. It is a natural polypeptidic complex with pharmacological potential because of its antitumoral properties which has attracted great interest for diagnosis and therapy of oncological diseases. However, Crotoxin mechanism of action and sites of specific interaction on tumor cells are still misunderstood. Breast cancer is the second most frequent type in the world and the most common cancer in women. About 30 to 60% of mammary tumors overexpress epidermal growth factor receptor (EGFR), a transmembrane protein related to cell proliferation. Since literature has reported that Crotoxin antitumoral effect is more potent on cells with EGFR overexpression the objectives of this work were to evaluate Crotoxin cytotoxic effects on mammary tumor cells human breast carcinoma (MCF-7) and Ehrlich tumor cells (murine ascitics carcinoma), and to investigate the specific molecular interaction of Crotoxin on Ehrlich tumor cells. Initially, Crotoxin was radiolabelled with iodine-125 ( 125 I-Crotoxin) and iodine-131 ( 131 I-Crotoxin). Saturation and competition assay were carried out to characterize Crotoxin in vitro interaction; Crotoxin biodistribution studies and singlephoton emission computed tomography (SPECT) of mice bearing Ehrlich tumor have been evaluated to describe in vivo interaction. Our results showed that Crotoxin presented cytotoxic effect against Ehrlich with DL 50 in vitro (concentration of compound which is lethal for 50% of cells) of about one micromolar, but did not present significant effect against MCF-7. Morphological alterations characteristic of apoptosis suggests programmed cell death. 125 I-Crotoxin interaction with Ehrlich tumor cells was saturable with approximately 70% specificity, and presented K d =24.98 nmol/L and B max =16,570 sites/cell for low affinity binding sites and K d =0.06 nmol/L and B max =210 sites/cell high affinity binding sites

  20. Evaluation of Worktext in Mechanical Drafting

    Directory of Open Access Journals (Sweden)

    Erich D. Cruz

    2015-11-01

    Full Text Available This study aimed to evaluate Worktext in Drafting Technology 4 (Mechanical Drafting for Bachelor of Technology (BT major in Drafting Technology. It was conducted at University of Rizal System with twenty Drafting and Mechanical Technology professors as respondents. The study used the descriptive evaluative method to describe and evaluate the developed Worktext in DT 4 using the questionnaire-checklist in gathering data. They were asked to evaluate the worktext through the following: objectives, contents, activities, presentation and style, organization, creativity, evaluation, accuracy, completeness and appropriateness. It was found out that the developed worktext with respect to objectives was highly agree, contents was highly agree, activities was highly agree, presentation and style was agree, creativity was highly agree and evaluation was highly agree. Meaning that the items with highly agree interpretations attained excellent level of acceptability while those with agree interpretations obtained extensive level of acceptability with fully achieved and above average Drafting standards, respectively. It was also found out that the developed worktext in terms of accuracy was high, completeness was very high and appropriateness was likewise very high. The researcher recommends that the developed Worktext in Drafting Technology 4 may be adopted for use by the Bachelor of Technology major in Drafting Technology students.

  1. Quality of protection evaluation of security mechanisms.

    Science.gov (United States)

    Ksiezopolski, Bogdan; Zurek, Tomasz; Mokkas, Michail

    2014-01-01

    Recent research indicates that during the design of teleinformatic system the tradeoff between the systems performance and the system protection should be made. The traditional approach assumes that the best way is to apply the strongest possible security measures. Unfortunately, the overestimation of security measures can lead to the unreasonable increase of system load. This is especially important in multimedia systems where the performance has critical character. In many cases determination of the required level of protection and adjustment of some security measures to these requirements increase system efficiency. Such an approach is achieved by means of the quality of protection models where the security measures are evaluated according to their influence on the system security. In the paper, we propose a model for QoP evaluation of security mechanisms. Owing to this model, one can quantify the influence of particular security mechanisms on ensuring security attributes. The methodology of our model preparation is described and based on it the case study analysis is presented. We support our method by the tool where the models can be defined and QoP evaluation can be performed. Finally, we have modelled TLS cryptographic protocol and presented the QoP security mechanisms evaluation for the selected versions of this protocol.

  2. Quality of Protection Evaluation of Security Mechanisms

    Science.gov (United States)

    Ksiezopolski, Bogdan; Zurek, Tomasz; Mokkas, Michail

    2014-01-01

    Recent research indicates that during the design of teleinformatic system the tradeoff between the systems performance and the system protection should be made. The traditional approach assumes that the best way is to apply the strongest possible security measures. Unfortunately, the overestimation of security measures can lead to the unreasonable increase of system load. This is especially important in multimedia systems where the performance has critical character. In many cases determination of the required level of protection and adjustment of some security measures to these requirements increase system efficiency. Such an approach is achieved by means of the quality of protection models where the security measures are evaluated according to their influence on the system security. In the paper, we propose a model for QoP evaluation of security mechanisms. Owing to this model, one can quantify the influence of particular security mechanisms on ensuring security attributes. The methodology of our model preparation is described and based on it the case study analysis is presented. We support our method by the tool where the models can be defined and QoP evaluation can be performed. Finally, we have modelled TLS cryptographic protocol and presented the QoP security mechanisms evaluation for the selected versions of this protocol. PMID:25136683

  3. Kinetics and mechanism of DNA repair; Evaluation of caged compounds for use in studies of u. v. -induced DNA repair

    Energy Technology Data Exchange (ETDEWEB)

    Meldrum, R.A.; Wharton, C.W. (Birmingham Univ. (UK). Dept. of Biochemistry); Shall, S. (Sussex Univ., Brighton (UK). School of Biological Sciences)

    1990-03-15

    Experiments are described in which the feasibility of using caged dideoxy and other nucleoside triphosphate analogues for trapping breaks induced by u.v. radiation damage to mammalian cell DNA is evaluated. These nucleotide analogues that have a photolabile 1-(2-nitrophenyl)ethyl-protecting group attached to the {gamma}-phosphate are placed in situ by permeabilizing cells by exposure to hypo-osmotic medium. The nucleoside triphosphate is released by a 351 nm u.v. laser pulse whence it may incorporate in the growing chain of DNA induced by the excision-repair process and terminate chain elongation. If the photoreleased dideoxynucleoside trisphosphate is isotopically labelled in the {alpha}-phosphate position the break is trapped and labelled. Incorporation of radioactivity into trichloroacetic acid insoluble material in these experiments confirms their potential for use in studies of the kinetics of mammalian cell DNA repair. (author).

  4. Mechanism of action study to evaluate the effect of rosiglitazone on bone in postmenopausal women with type 2 diabetes mellitus: rationale, study design and baseline characteristics

    Science.gov (United States)

    Fitzpatrick, Lorraine A.; Bilezikian, John P.; Wooddell, Margaret; Paul, Gitanjali; Kolatkar, Nikheel S.; Nino, Antonio J.; Miller, Colin G.; Bogado, Cesar E.; Arnaud, Claude D.; Cobitz, Alexander R.

    2012-01-01

    Objectives Post-hoc analyses have shown an increase incidence of fractures among type 2 diabetes (T2DM) patients treated with thiazolidinediones (TZDs). The mechanisms by which TZDs may be associated with increased fracture risk is not well understood. This article describes the study design and baseline characteristics for a prospective, randomized, double-blind, active-controlled trial to evaluate the effects of rosiglitazone on changes in measures of skeletal structure, surrogates of bone strength and metabolism. Methods Postmenopausal women without osteoporosis and diagnosed with T2DM were randomized in a double-blind design to either rosiglitazone or metformin for 52 weeks, then all subjects received open-label metformin for 24 weeks. Study endpoints included changes in bone mineral density (BMD), quantitative computed tomography (QCT), digitized hip radiography (HXR) and high resolution magnetic resonance imaging (hrMRI). Serum markers of bone metabolism and indices of glycemic control were assessed within and between treatment groups. Results A total of 226 subjects were randomized. Baseline characteristics included: age 63.8 ± 6.5 years; years postmenopausal 16.9 ± 8.4; duration of diabetes 3.5 (1.8–7.8) years; body mass index (BMI) 31.4 ± 5.9 kg/m2; and glycated hemoglobin (HbA1c) 6.4 ± 0.65%. At baseline, mean T-scores were −0.95 ± 0.91 at the femoral neck, −0.02 ± 0.97 at the total hip and −0.55 ± 1.25 at the total spine. Since there are no well recognized techniques to determine bone mass and structure at the distal limbs (cortical bone sites where fractures were reported in RSG subjects), using the femoral neck as a surrogate for these areas may be a potential limitation of the study. Conclusion This is the first randomized trial utilizing multiple techniques to evaluate bone mass, structure, serum markers of bone remodeling, and potential reversibility of changes after discontinuation of rosiglitazone. This

  5. Study of the mechanisms underlying resumptions of alteration. Modeling and evaluation of the impact on nuclear waste glasses

    International Nuclear Information System (INIS)

    Fournier, Maxime

    2015-01-01

    A sudden and still poorly understood phenomenon, the resumption of alteration results in a sudden acceleration of the glass alteration rate due to the destabilization of the amorphous passivating layer formed on the glass surface. Understanding the origin and the consequences of this phenomenon is a major issue for the prediction of nuclear glass long-term behavior. This study quantitatively links the alteration degree of a six-oxide reference glass and the formation mechanisms of zeolites and C-S-H that control the solution chemistry. The role played by the decrease in aluminum concentration as an indicator of resumption is highlighted. It appears that the resumption occurrence and rate are correlated to the couple (T, pH), but even in the most adverse situations the resumption rate is lower than the initial alteration rate, which remains the fastest kinetic regime. Previously limited to alkaline pH, the characterization of alteration resumptions was extended to conditions more representative of those found in a geological repository. This approach required the development of a new tool: seeding, that reduces or eliminates the latency period preceding a resumption. The results obtained demonstrate its usefulness in understanding the role of zeolites in amorphous layer destabilization and for modeling alteration resumptions. A geochemical modeling approach to alteration resumption is proposed, based on the formalism of the GRAAL glass alteration model. It is based on the calculation of zeolite thermodynamic constants, on the implementation of their nucleation and growth kinetics, and on assumptions related to the solubility of the amorphous layer. When zeolite precipitation consumes alkali, glass alteration - driven by zeolite precipitation - releases alkali. The model highlights the importance of such chemical couplings and shows that, in the stoichiometry of French nuclear reference glass, their cumulative effects are the cause of a pH decrease which limits

  6. Evaluation of Purinergic Mechanism for the Treatment of Voiding Dysfunction: A Study in Conscious Spinal Cord-injured Rats

    Directory of Open Access Journals (Sweden)

    Shing-Hwa Lu

    2007-10-01

    Conclusion: These results indicate that purinergic mechanisms, presumably involving P2X3 or P2X2/3 receptors on bladder C-fiber afferent nerves, play an important role in the detrusor hyperreflexia that occurs after spinal cord injury in rats.

  7. Optimization evaluation of cutting technology based on mechanical parts

    Science.gov (United States)

    Wang, Yu

    2018-04-01

    The relationship between the mechanical manufacturing process and the carbon emission is studied on the basis of the process of the mechanical manufacturing process. The formula of carbon emission calculation suitable for mechanical manufacturing process is derived. Based on this, a green evaluation method for cold machining process of mechanical parts is proposed. The application verification and data analysis of the proposed evaluation method are carried out by an example. The results show that there is a great relationship between the mechanical manufacturing process data and carbon emissions.

  8. Evaluation of mechanical and histological properties of cryopreserved human premolars under short-term preservation: A preliminary study

    Directory of Open Access Journals (Sweden)

    Shu-Li Lin

    2014-09-01

    Conclusion: This study demonstrated that exposure to transportation solution for 24 hours followed by storage in a programmed freezer did not negatively affect the cell density or the elastic modulus of the pulp tissue.

  9. Mechanized evaluation of neutron cross-sections

    International Nuclear Information System (INIS)

    Horsley, A.; Parker, J.B.

    1967-01-01

    The evaluation work to provide accurate and consistent neutron cross-section data for multigroup neutronics calculations is not fully exploiting the available theoretical and experimental results; this has been so particularly since the introduction of on-line data handling techniques enabled experimenters to turn out vast quantities of numbers. This situation can be radically improved only by mechanizing the evaluation processes. Systems such as the SC1SRS tape will not only largely overcome the task of collecting data but will provide speedy access to it; by using computers and graph-plotting machines to tabulate and display this data, the labour of evaluation can be very greatly reduced. With some types of cross-section there is hope that by using modern curve-fitting techniques the actual evaluation and statistical accounting of the data can be performed automatically. Some areas where automatic evaluation would seem likely to succeed are specified and a discussion of the mathematical difficulties incurred, such as the elimination of anomalous data, is given. Particularly promising is the use of splines in the mechanized evaluation of data. Splines are the mathematical analogues of the draughtsman's spline used in drawing smooth curves. Their principal properties are the excellent approximations they give to the derivatives of a function; in contrast to conventional polynomial fitting, this feature ensures good interpolation and, when required, stable extrapolation. Various methods of using splines in data graduation and the problem of marrying these methods to standard statistical procedures are examined. The results of work done at AWRE with cubic splines on the mechanized evaluation of neutron scattering total cross-section and angular distribution data are presented. (author)

  10. Evaluation of purinergic mechanism for the treatment of voiding dysfunction: a study in conscious spinal cord-injured rats.

    Science.gov (United States)

    Lu, Shing-Hwa; Groat, William C de; Lin, Alex T L; Chen, Kuang-Kuo; Chang, Luke S

    2007-10-01

    To investigate the effect of a selective P2X(3-)P2X(2/3) purinergic receptor antagonist (a-317491) on detrusor hyperreflexia in conscious chronic spinal cord-injured female rats. Six chronic spinal cord-transected female Sprague-Dawley rats (290-336 g) were used in this study. Spinal transection at the T8-T9 segmental level was performed using aseptic techniques under halothane anesthesia. Fourteen to 16 weeks after spinal transection, A-317491, a selective P2X(3-)P2X(2/3) purinergic receptor antagonist, was administered intravenously in cystometry studies at increasing doses of 0.03, 0.1, 0.3, 1, 3, 10 and 30 micromol/kg at 40-50 minute intervals. Cystometrograms (CMGs) were performed before and after the administration of each dose of the drug. The continuous filling of CMGs revealed a large number of small-amplitude (> 8 cmH(2)O), non-voiding contractions (NVCs) (average, 9.7 per voiding cycle) preceding voiding contractions (mean amplitude, 31 cmH(2)O; duration, 2.5 minutes), which occurred at an interval of 539 seconds and at a pressure threshold of 5.7 cmH(2)O. When tested in a range of doses (0.03-30 micromol/kg, intravenous), A-317491 in doses between 1 and 30 micromol/kg significantly (p spinal cord injury in rats.

  11. Maxillary incisor retraction: evaluation of different mechanisms

    Directory of Open Access Journals (Sweden)

    Antônio Carlos de Oliveira Ruellas

    2013-04-01

    Full Text Available OBJECTIVE: To mechanically evaluate different systems used for incisors retraction. METHODS: Three different methods for incisors retraction using 0.019 x 0.025-in stainless steel wire were evaluated. The samples were divided into three groups: Group A (retraction arch with 7-mm high vertical hooks; Group G3 (elastic chain attached to the miniimplant and to the 3-mm stainless steel hook soldered to the retraction arch; Group G6 (elastic chain attached to the mini-implant and to the 6-mm stainless steel hook soldered to the retraction arch. A dental mannequin was used for evaluation in order to simulate the desired movements when the device was exposed to a heat source. The analysis of variance (ANOVA and the Tukey test were used (p < 0.05. RESULTS: The results demonstrated that Groups G3 and G6 exhibited less extrusion and less incisor inclination during the retraction phase (p < 0.05. With regard to incisor extrusion, statistically significant differences were observed between Groups A and G3, and between Groups A and G6 (p < 0.05. Regarding incisor inclination, statistically significant differences were observed between the three systems evaluated (p < 0.05. CONCLUSIONS: Arches with 6-mm vertical hooks allow the force to be applied on the center of resistance of the incisors, thus improving mechanical control when compared with the other two systems.

  12. Evaluation of potential reaction mechanisms leading to the formation of coniferyl alcohol α-linkages in lignin: a density functional theory study.

    Science.gov (United States)

    Watts, Heath D; Mohamed, Mohamed Naseer Ali; Kubicki, James D

    2011-12-21

    Five potential reaction mechanisms, each leading to the formation of an α-O-4-linked coniferyl alcohol dimer, and one scheme leading to the formation of a recently proposed free-radical coniferyl alcohol trimer were assessed using density functional theory (DFT) calculations. These potential reaction mechanisms were evaluated using both the calculated Gibbs free energies, to predict the spontaneity of the constituent reactions, and the electron-density mapped Fukui function, to determine the most reactive sites of each intermediate species. The results indicate that each reaction in one of the six mechanisms is thermodynamically favorable to those in the other mechanisms; what is more, the Fukui function for each free radical intermediate corroborates with the thermochemical results for this mechanism. This mechanism proceeds via the formation of two distinct free-radical intermediates, which then react to produce the four α-O-4 stereoisomers.

  13. Evaluation of chemical and/or mechanical treatments of the smear layer as revealed by scanning electron microscopy - a blind comparative study

    Directory of Open Access Journals (Sweden)

    LUZ Maria Aparecida Alves de Cerqueira

    2000-01-01

    Full Text Available A blind comparative study of chemical and/or mechanical treatments of the smear layer, according to scanning electron microscopy images, was carried out. The effect of the treatments was analyzed on the smear layer of mesio-occlusodistal cavity walls prepared in vitro in human third molars. The agents used were air/water spray, 37% phosphoric acid, 5% tannic acid, biologic detergent, 0.5% sodium hypochlorite, and enamel hatchet alone or in association with the previous agents. Electron micrographs were evaluated by three professionals according to the degree of visualization of underlying dentin or enamel. Phosphoric acid received the highest scores due to the complete removal of the smear layer. However, statistical analyses revealed diverse performances of non or slightly demineralizing agents, according to the cavity walls in dentin, while there was equivalent effect on the enamel of gingival walls.

  14. A comparative study to evaluate the effects of ligation methods on friction in sliding mechanics using 0.022" slot brackets in dry state: An In-vitro study.

    Science.gov (United States)

    Vinay, K; Venkatesh, M J; Nayak, Rabindra S; Pasha, Azam; Rajesh, M; Kumar, Pradeep

    2014-04-01

    Friction between archwires and brackets is assuming greater importance for finishing with increased use of sliding mechanics in orthodontics as friction impedes the desired tooth movement. The following study is conducted to compare and evaluate the effect of ligation on friction in sliding mechanics using 0.022" slot bracket in dry condition. In the study 48 combinations of brackets, archwires and different ligation techniques were tested in order to provide best combination that offers less friction during sliding mechanics. Instron- 4467 machine was used to evaluate static and kinetic friction force values and the results were subjected to Statistical Analysis and Anova test. The results of the study showed that 0.022" metal brackets, Stainless steel wires and Slick modules provided the optimum frictional resistance to sliding mechanics. It is observed that frictional forces of 0.019" x 0.025" were higher when compared with 0.016" x 0.022" Stainless steel archwire due to the increase in dimension. Self-ligating brackets offered least friction followed by mini twin, variable force, regular stainless steel, ceramic with metal insert bracket and ceramic brackets. The stainless steel ligature offered less resistance than slick and grey modules, and TMA wires recorded maximum friction. The stainless steel archwire of 0.019" x 0.025" dimension are preferred during sliding mechanics, these archwires with variable force brackets ligated with Slick Modules offer decreased friction and is cost effective combination which can be utilized during sliding mechanics. How to cite the article: Vinay K, Venkatesh MJ, Nayak RS, Pasha A, Rajesh M, Kumar P. A comparative study to evaluate the effects of ligation methods on friction in sliding mechanics using 0.022" slot brackets in dry state: An In-vitro study. J Int Oral Health 2014;6(2):76-83.

  15. Fracture mechanics evaluation of heavy welded structures

    International Nuclear Information System (INIS)

    Sprung, I.; Ericksson, C.W.; Zilberstein, V.A.

    1982-01-01

    This paper describes some applications of nondestructive examination (NDE) and engineering fracture mechanics to evaluation of flaws in heavy welded structures. The paper discusses not only widely recognized linear elastic fracture mechanics (LEFM) analysis, but also methods of the elastic-plastic fracture mechanics (EPFM), such as COD, J-integral, and Failure Assessment Diagram. Examples are given to highlight the importance of interaction between specialists providing input and the specialists performing the analysis. The paper points out that the critical parameters for as-welded structures when calculated by these methods are conservative since they are based on two pessimistic assumptions: that the magnitude of residual stress is always at the yield strength level, and that the residual stress always acts in the same direction as the applied (mechanical) stress. The suggestion is made that it would be prudent to use the COD or the FAD design curves for a conservative design. The appendix examines a J-design curve modified to include residual stresses

  16. Comparative evaluation of different mechanical modifications of denture teeth on bond strength between high-impact acrylic resin and denture teeth: An in vitro study.

    Science.gov (United States)

    Phukela, Sumit Singh; Chintalapudi, Siddesh Kumar; Sachdeva, Harleen; Dhall, Rupinder Singh; Sharma, Neeraj; Prabhu, Allama

    2016-01-01

    Acrylic teeth separates from the denture base and remains a major worry in day-to-day routine dental procedure. The present study was conducted to comparatively evaluate different mechanical modifications of acrylic teeth on bond strength between Lucitone 199 heat cure resin and cross-linked teeth. The test specimens, central incisors (21) were demarcated into four groups. Group 1 was the control group, whereas Group 2, Group 3, and Group 4 were experimental groups modified with round groove, vertical groove, and T-shaped groove, respectively. The preparation of masterpiece was done by aligning the long axis of the central incisor teeth at 45° to the base of a wax block (8 mm × 10 mm × 30 mm), with ridge lap surface contacting the base. These test specimen (21) was prepared by Lucitone 199 heat cure resin. Evaluation of bond strength of all the specimens was done using universal tester (materials testing machine). Shapiro-Wilk Test, one-way analysis of variance (ANOVA), and Bonferroni test were done to do statistical investigation. Group 1 specimens prepared by Lucitone 199 heat cure resin showed the lowest bond strength and Group 4 specimens prepared with T-shaped groove packed with Lucitone 199 exhibited the highest bond strength. The bond strength between Lucitone 199 heat cure resin and cross-linked teeth was increased when mechanical modifications was done on denture teeth. The specimens prepared with T-shaped groove packed with Lucitone 199 heat cure resin showed the highest bond strength followed by Group 3, Group 2, and lastly Group 1 prepared by Lucitone 199 heat cure resin.

  17. Echocardiographic evaluation during weaning from mechanical ventilation

    Directory of Open Access Journals (Sweden)

    Luciele Medianeira Schifelbain

    2011-01-01

    Full Text Available INTRODUCTION: Echocardiographic, electrocardiographic and other cardiorespiratory variables can change during weaning from mechanical ventilation. OBJECTIVES: To analyze changes in cardiac function, using Doppler echocardiogram, in critical patients during weaning from mechanical ventilation, using two different weaning methods: pressure support ventilation and T-tube; and comparing patient subgroups: success vs. failure in weaning. METHODS: Randomized crossover clinical trial including patients under mechanical ventilation for more than 48 h and considered ready for weaning. Cardiorespiratory variables, oxygenation, electrocardiogram and Doppler echocardiogram findings were analyzed at baseline and after 30 min in pressure support ventilation and T-tube. Pressure support ventilation vs. T-tube and weaning success vs. failure were compared using ANOVA and Student's t-test. The level of significance was p<0.05. RESULTS: Twenty-four adult patients were evaluated. Seven patients failed at the first weaning attempt. No echocardiographic or electrocardiographic differences were observed between pressure support ventilation and T-tube. Weaning failure patients presented increases in left atrium, intraventricular septum thickness, posterior wall thickness and diameter of left ventricle and shorter isovolumetric relaxation time. Successfully weaned patients had higher levels of oxygenation. CONCLUSION: No differences were observed between Doppler echocardiographic variables and electrocardiographic and other cardiorespiratory variables during pressure support ventilation and T-tube. However cardiac structures were smaller, isovolumetric relaxation time was larger, and oxygenation level was greater in successfully weaned patients

  18. Systematic evaluation of skeletal mechanical function.

    Science.gov (United States)

    Smith, Lauren; Bigelow, Erin M R; Jepsen, Karl J

    2013-06-01

    Many genetic and environmental perturbations lead to measurable changes in bone morphology, matrix composition, and matrix organization. The skeletal system is highly adaptive, such that genetic and environmental perturbations affecting one trait are often accompanied by compensatory changes in other traits. This adaptation should be considered when attempting to draw meaningful conclusions about the role of a gene, for example. The challenge is to figure out which alterations can be attributed to the perturbation and which result from adaptive changes associated with establishing mechanical function. The goal of this chapter is to describe straight-forward biomechanical methods that can be used to determine whether a genetic or environmental perturbation affected bone strength. We introduce a systematic method for evaluating how bone strength was altered in the context of morphology and tissue-level mechanical properties, which are determined in large part from matrix composition, matrix organization, and porosity. We present this work as a first step toward screening mice for a phenotypic effect and for establishing the associated biomechanical mechanism by which function was altered. The outcome of these analyses generally provides insight into the next set of experiments required to further connect the cellular perturbation with the functional changes. The protocols were written to enable researchers without a background in engineering to conduct the assays or to enable researchers to better understand the outcomes of similar assays conducted by colleagues knowledgeable in engineering.

  19. To Study Capping or Lamination Tendency of Tablets Through Evaluation of Powder Rheological Properties and Tablet Mechanical Properties of Directly Compressible Blends.

    Science.gov (United States)

    Dudhat, Siddhi M; Kettler, Charles N; Dave, Rutesh H

    2017-05-01

    Air entrapment efficiency of the powders is one of the main factors leading to occurrence of capping or lamination tendency of tablets manufactured from the directly compressible powder blends. The purpose of the current research was to study this underlying cause leading to occurrence of capping or lamination of tablets through evaluation of powder rheological properties. Powder blends were prepared by addition of 0% w/w to 100% w/w of individual active pharmaceutical ingredient (API) [two model API: acetaminophen (APAP) and ibuprofen (IBU)] with microcrystalline cellulose without and with 0.5% w/w Magnesium Stearate as lubricant. Powder rheological properties were analyzed using FT4 Powder Rheometer for dynamic, bulk, and shear properties. Tablet mechanical properties of the respective blends were studied by determining the ability of the material to form tablet of specific strength under applied compaction pressure through tabletability profile. The results showed that powder rheometer distinguished the powder blends based on their ability to relieve entrapped air along with the distinctive flow characteristics. Powder blend prepared with increasing addition of APAP displayed low powder permeability as compared to IBU blends with better powder permeability, compressibility and flow characteristics. Also, lubrication of the APAP blends did not ease their ability to relieve air. Tabletability profiles revealed the potential occurrence of capping or lamination in tablets prepared from the powder blends with high APAP content. This study can help scientist to understand tableting performance at the early-developmental stages and can avoid occurrence capping and lamination of tablets.

  20. Delirium and coma evaluated in mechanically ventilated patients in the intensive care unit in Japan: a multi-institutional prospective observational study.

    Science.gov (United States)

    Tsuruta, Ryosuke; Oda, Yasutaka; Shintani, Ayumi; Nunomiya, Shin; Hashimoto, Satoru; Nakagawa, Takashi; Oida, Yasuhisa; Miyazaki, Dai; Yabe, Shigemi

    2014-06-01

    The object of this study is to evaluate the prevalence and effects of delirium on 28-day mortality in critically ill patients on mechanical ventilation in Japan. Prospective cohort study was conducted in medical and surgical intensive care units (ICUs) of 24 medical centers. Patients were followed up daily for delirium during ICU stay after enrollment. Coma was defined with the Richmond Agitation Sedation Scale score of -4 or -5. Delirium was diagnosed using the Confusion Assessment Method for the ICU. The Cox proportional hazards regression model was used to assess the effects of delirium and coma on 28-day mortality, time to extubation, and time to ICU discharge; delirium and coma were included as time-varying covariates after controlling for age, Acute Physiology and Chronic Health Evaluation II score, ventilator-associated pneumonia, and the reason for intubation with infection. Of 180 patients, 115 patients (64%) developed delirium. Moreover, 15 patients (8%) died within 28 days after ICU admission, including 7 patients who experienced coma and 8 patients who experienced both coma and delirium. There were no deaths among patients who did not experience coma. Delirium was associated with a shorter time to extubation (hazard ratio [HR], 2.52; 95% confidence interval [CI], 1.65-3.85; Pcoma, although statistical significance was not detected due to limited analytical power (HR, 0.62; 95% CI, 0.34-1.12; P=.114). Delirium during ICU stay was not associated with higher mortality. Further study is needed to investigate the discrepancy between these and previous data. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Evaluation of mechanical properties of esthetic brackets

    OpenAIRE

    Matsui, Shigeyuki; Umezaki, Eisaku; Komazawa, Daigo; Otsuka, Yuichiro; Suda, Naoto

    2015-01-01

    Plastic brackets, as well as ceramic brackets, are used in various cases since they have excellent esthetics. However, their mechanical properties remain uncertain. The purpose of this study was to determine how deformation and stress distribution in esthetic brackets differ among materials under the same wire load. Using the digital image correlation method, we discovered the following: (1) the strain of the wings of plastic brackets is within 0.2% and that of ceramic and metal brackets is n...

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

    African Journals Online (AJOL)

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

  3. Evaluation of mechanical load in the musculoskeletal system : development of experimental and modeling methodologies for the study of the effect of exercise in human models

    OpenAIRE

    João, Filipa Oliveira da Silva

    2013-01-01

    Doutoramento em Motricidade Humana, na especialidade de Biomecânica A major concern of Biomechanics research is the evaluation of the mechanical load and power that the human body develops and endorses when performing high to moderate sport activities. With the purpose of increasing performance and reducing the risk of injury, substantial advances were accomplished to pursuit this goal, either on the laboratory techniques as well as modelling and simulation. Traditionally, the main focus w...

  4. Studies in mathematics and mechanics

    CERN Document Server

    von Mises, Richard

    2013-01-01

    Studies in Mathematics and Mechanics is a collection of studies presented to Professor Richard von Mises as a token of reverence and appreciation on the occasion of his seventieth birthday which occurred on April 19, 1953. von Mises' thought has been a stimulus in many seemingly unconnected fields of mathematics, science, and philosophy, to which he has contributed decisive results and new formulations of fundamental concepts. The book contains 42 chapters organized into five parts. Part I contains papers on algebra, number theory and geometry. These include a study of Poincaré's representatio

  5. Evaluation of Mechanical Parameters of Pellets

    Directory of Open Access Journals (Sweden)

    Ľubomír Kubík

    2016-01-01

    Full Text Available The paper dealt with the evaluation of mechanical properties of the cylinder wheat straw, rapeseed straw and 50/50 % mixed wheat and rapeseed straw pellet samples. The pellets were made by the granulating machine MGL 200 (Kovonovak. The compressive loading curves of dependencies of stress on strain were realised by the test stand Andilog Stentor 1000 (Andilog Technologies, Vitrolles, France. Certain mechanical parameters were determined, namely the initial force (force at 10 % of compress strain, force in maximum of loading curve, strain in maximum of loading curve, initial stress (stress at 10 % of compression strain, stress in maximum of loading curve and modulus of elasticity. Mean value of the initial force was maximal for mixed straw pellet samples 52.49 N. Mean values of the initial force of the wheat straw samples and the rapeseed straw samples were smaller and almost identical 43.58 N and 43.12 N. Mean values of the initial stress of loading curve, of the wheat straw samples reached 1.46 MPa, the rapeseed straw samples reached value 1.40 MPa and the mixed straw samples reached value 1.63 MPa. Mean value of the force in maximum of loading curve was also maximal for mixed straw pellet samples 213.26 N. Mean values of the force in maximum of loading curve of the wheat straw samples reached 178.11 N. The rapeseed straw samples reached value 95.95 N and the mixed straw samples reached value 213.26 N. Mean values of the stress in maximum of loading curve, of the wheat straw samples reached 5.93 MPa, the rapeseed straw samples reached value 3.11 MPa and the mixed straw samples reached value 7.10 MPa Mean values of the modulus of elasticity, of the wheat straw samples reached 18.27 MPa, the rapeseed straw samples reached value 13.08 MPa and the mixed straw samples reached value 14.97 MPa. Significant correlations of the mechanical parameters pellet samples were observed among initial force and initial stress and modulus of elasticity

  6. Evaluation of the Effectiveness of the Integration of a LITEE Case Study for a Freshman Level Mechanical Engineering Course at The University of Toledo

    Science.gov (United States)

    Franchetti, Matthew

    2011-01-01

    The purpose of this paper is to report the findings of the integration of a manufacturing case study to a freshman level mechanical engineering course at The University of Toledo. The approach to integrate this case study into the class was completed via weekly assignments analyzing the case, small group discussion, and weekly group discussion.…

  7. Tank waste concentration mechanism study

    International Nuclear Information System (INIS)

    Pan, L.C.; Johnson, L.J.

    1994-09-01

    This study determines whether the existing 242-A Evaporator should continue to be used to concentrate the Hanford Site radioactive liquid tank wastes or be replaced by an alternative waste concentration process. Using the same philosophy, the study also determines what the waste concentration mechanism should be for the future TWRS program. Excess water from liquid DST waste should be removed to reduce the volume of waste feed for pretreatment, immobilization, and to free up storage capacity in existing tanks to support interim stabilization of SSTS, terminal cleanout of excess facilities, and other site remediation activities

  8. Mechanical Evaluation of Polymer Composite Hip Protectors

    Directory of Open Access Journals (Sweden)

    Jose Daniel Diniz Melo

    2010-01-01

    Full Text Available Hip fractures often result in serious health implications, particularly in the geriatric population, and have been related to long-term morbidity and death. In most cases, these fractures are caused by impact loads in the area of the greater trochanter, which are produced in a fall. This work is aimed at developing hip protectors using composite materials and evaluating their effectiveness in preventing hip fractures under high impact energy (120 J. The hip protectors were developed with an inner layer of energy absorbing soft material and an outer rigid shell of fiberglass-reinforced polymer composite. According to the experimental results, all tested configurations proved to be effective at reducing the impact load to below the average fracture threshold of proximal femur. Furthermore, an addition of Ethylene Vinyl Acetate (EVA to the impacted area of the composite shell proved to be beneficial to increase impact strength of the hip protectors. Thus, composite hip protectors proved to be a viable alternative for a mechanically efficient and cost-effective solution to prevent hip fractures.

  9. Electric utility engineer`s FGD manual -- Volume 2: Major mechanical equipment; FGD proposal evaluations; Use of FGDPRISM in FGD system modification, proposal, evaluation, and design; FGD system case study. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-03-04

    Part 2 of this manual provides the electric utility engineer with detailed technical information on some of the major mechanical equipment used in the FGD system. The objectives of Part 2 are the following: to provide the electric utility engineer with information on equipment that may be unfamiliar to him, including ball mills, vacuum filters, and mist eliminators; and to identify the unique technique considerations imposed by an FGD system on more familiar electric utility equipment such as fans, gas dampers, piping, valves, and pumps. Part 3 provides an overview of the recommended procedures for evaluating proposals received from FGD system vendors. The objectives are to provide procedures for evaluating the technical aspects of proposals, and to provide procedures for determining the total costs of proposals considering both initial capital costs and annual operating and maintenance costs. The primary objective of Part 4 of this manual is to provide the utility engineer who has a special interest in the capabilities of FGDPRISM [Flue Gas Desulfurization PRocess Integration and Simulation Model] with more detailed discussions of its uses, requirements, and limitations. Part 5 is a case study in using this manual in the preparation of a purchase specification and in the evaluation of proposals received from vendors. The objectives are to demonstrate how the information contained in Parts 1 and 2 can be used to improve the technical content of an FGD system purchase specification; to demonstrate how the techniques presented in Part 3 can be used to evaluate proposals received in response to the purchase specification; and to illustrate how the FGDPRISM computer program can be used to establish design parameters for the specification and evaluate vendor designs.

  10. Evaluation of mechanical properties of esthetic brackets.

    Science.gov (United States)

    Matsui, Shigeyuki; Umezaki, Eisaku; Komazawa, Daigo; Otsuka, Yuichiro; Suda, Naoto

    2015-01-01

    Plastic brackets, as well as ceramic brackets, are used in various cases since they have excellent esthetics. However, their mechanical properties remain uncertain. The purpose of this study was to determine how deformation and stress distribution in esthetic brackets differ among materials under the same wire load. Using the digital image correlation method, we discovered the following: (1) the strain of the wings of plastic brackets is within 0.2% and that of ceramic and metal brackets is negligible, (2) polycarbonate brackets having a stainless steel slot show significantly smaller displacement than other plastic brackets, and (3) there is a significant difference between plastic brackets and ceramic and stainless steel brackets in terms of the displacement of the bracket wing.

  11. Methods for evaluation of mechanical stress condition of materials

    Directory of Open Access Journals (Sweden)

    Mirchev Yordan

    2018-01-01

    Full Text Available Primary attention is given to the following methods: method by drilling cylindrical holes (drill method and integrated ultrasonic method using volume (longitudinal and transverse, surface, and sub-surface waves. Drill method allows determination of residual mechanical stress in small depth of material surfaces, assessing type, size, and orientation of principal stresses. For the first time, parallel studies are carried out of mechanical stress in materials using the electroacoustic effect of volume, surface and sub-surface waves on the one hand, and effective mechanical stresses on the other. The experimental results present electroacoustic coefficients for different types of waves in the material of gas pipeline tube of 243 mm diameter and 14 mm thickness. These are used to evaluate mechanical stresses in pipelines, according to active GOST standards.

  12. [Research progress on mechanical performance evaluation of artificial intervertebral disc].

    Science.gov (United States)

    Li, Rui; Wang, Song; Liao, Zhenhua; Liu, Weiqiang

    2018-03-01

    The mechanical properties of artificial intervertebral disc (AID) are related to long-term reliability of prosthesis. There are three testing methods involved in the mechanical performance evaluation of AID based on different tools: the testing method using mechanical simulator, in vitro specimen testing method and finite element analysis method. In this study, the testing standard, testing equipment and materials of AID were firstly introduced. Then, the present status of AID static mechanical properties test (static axial compression, static axial compression-shear), dynamic mechanical properties test (dynamic axial compression, dynamic axial compression-shear), creep and stress relaxation test, device pushout test, core pushout test, subsidence test, etc. were focused on. The experimental techniques using in vitro specimen testing method and testing results of available artificial discs were summarized. The experimental methods and research status of finite element analysis were also summarized. Finally, the research trends of AID mechanical performance evaluation were forecasted. The simulator, load, dynamic cycle, motion mode, specimen and test standard would be important research fields in the future.

  13. Postamputation pain: studies on mechanisms.

    Science.gov (United States)

    Nikolajsen, Lone

    2012-10-01

    Amputation is followed by both painful and non-painful phantom phenomena in a large number of amputees. Non-painful phantom sensations rarely pose any clinical problem, but 60-80% of all amputees also experience painful sensations (i.e. phantom pain) located to the missing limb. The severity of phantom pain usually decreases with time, but severe pain persists in 5-10% of patients. Pain in the residual limb (i.e. stump pain) is another consequence of amputation. Both stump and phantom pain can be very difficult to treat. Treatment guidelines used for other neuropathic pain conditions are probably the best approximation, especially for the treatment of stump pain. The aim of the present doctoral thesis was to explore some of the mechanisms underlying pain after amputation. Ten studies were carried out (I-X). My PhD thesis from 1998 dealt with pain before the amputation and showed that preamputation pain increases the risk of phantom pain after amputation (I). A perioperative epidural blockade, however, did not reduce the incidence of pain or abnormal sensory phenomena after amputation (II, III). The importance of sensitization before amputation for the subsequent development of pain is supported by study IV, in which pressure pain thresholds obtained at the limb before amputation were inversely related to stump and phantom pain after 1 week. Afferent input from the periphery is likely to contribute to postamputation pain as sodium channels were upregulated in human neuromas (VI), although neuroma removal did not always alleviate phantom pain (V). Sensitization of neurons in the spinal cord also seems to be involved in pain after amputation as phantom pain was reduced by ketamine, an NMDA-receptor antagonist. Another NMDA-receptor antagonist, memantine, and gabapentin, a drug working by binding to the δ2α-subunit of voltage-gated calcium channels, had no effect on phantom pain (VII-IX). Supraspinal factors are also important for pain after amputation as

  14. Evaluation of structural deformations of a mechanical connecting unit oxidizer supplies by thermo-mechanical simulation

    International Nuclear Information System (INIS)

    Kim, Sang Woo

    2016-01-01

    A Mechanical connecting unit (MCU) used in ground facilities for a Liquid propellant rocket (LPR) acts as a bridge between the onboard system and the ground oxidizer filling system. It should be resistant to structural deformations in order to guarantee successful supply of a cryogenic oxidizer and high pressure gases without reduction of sealing capability. The MCU consists of many components and linkages and operates under harsh conditions induced by a cryogenic oxidizer, high pressure gases and other mechanical forces. Thus, the evaluation of structural deformation of the MCU considering complex conditions is expensive and time consuming. The present study efficiently evaluates the structural deformations of the key components of the MCU by Thermo-mechanical simulation (TMS) based on the superposition principle. Deformations due to the mechanical loadings including weights, pressures, and spring forces are firstly evaluated by using a non-linear flexible body simulation module (FFlex) of Multi-body dynamics (MBD) software, RecurDyn. Then, thermal deformations for the deformed geometries obtained by RecurDyn were subsequently calculated. It was conducted by using a Finite element (FE) analysis software, ANSYS. The total deformations for the onboard plate and multi-channel plate in the connecting section due to the mechanical and thermal loadings were successfully evaluated. Moreover, the outer gaps at six points between two plates were calculated and verified by comparison to the measured data. Their values and tendencies showed a good agreement. The author concluded that the TMS using MBD software considering flexible bodies and an FE simulator can efficiently evaluate structural deformations of the MCU operating under the complex load and boundary conditions

  15. Evaluation of structural deformations of a mechanical connecting unit oxidizer supplies by thermo-mechanical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sang Woo [Dept. of Mechanical Engineering, Institute of Machine Convergence Technology, Hankyong National University, Anseong (Korea, Republic of)

    2016-10-15

    A Mechanical connecting unit (MCU) used in ground facilities for a Liquid propellant rocket (LPR) acts as a bridge between the onboard system and the ground oxidizer filling system. It should be resistant to structural deformations in order to guarantee successful supply of a cryogenic oxidizer and high pressure gases without reduction of sealing capability. The MCU consists of many components and linkages and operates under harsh conditions induced by a cryogenic oxidizer, high pressure gases and other mechanical forces. Thus, the evaluation of structural deformation of the MCU considering complex conditions is expensive and time consuming. The present study efficiently evaluates the structural deformations of the key components of the MCU by Thermo-mechanical simulation (TMS) based on the superposition principle. Deformations due to the mechanical loadings including weights, pressures, and spring forces are firstly evaluated by using a non-linear flexible body simulation module (FFlex) of Multi-body dynamics (MBD) software, RecurDyn. Then, thermal deformations for the deformed geometries obtained by RecurDyn were subsequently calculated. It was conducted by using a Finite element (FE) analysis software, ANSYS. The total deformations for the onboard plate and multi-channel plate in the connecting section due to the mechanical and thermal loadings were successfully evaluated. Moreover, the outer gaps at six points between two plates were calculated and verified by comparison to the measured data. Their values and tendencies showed a good agreement. The author concluded that the TMS using MBD software considering flexible bodies and an FE simulator can efficiently evaluate structural deformations of the MCU operating under the complex load and boundary conditions.

  16. Evaluation of mechanical harvesting in viticulture

    Directory of Open Access Journals (Sweden)

    Pavel Zemánek

    2005-01-01

    Full Text Available Harvesting by mashine was in CZ tested at bygones century (70th. Tests rekord were bad (high share of leaf, detritus of concrete column, losses of berries.Lasting fall of worker in agriculture and vehement growth floricultural surfaces – vineyard (somewhere 19.000 hectare, requires complex rationalization and mechanization of all works stages which needs needlework. Harvisting in viniculture needs perhaps 30% of all working time (200–250 o‘clock on 1 hectare. Incidence thereof begun most of bigger producers in our country with mechanical harvisting. Technical performance of this machines turn up. There are not available data about costs and their work quality.The benefit deal with classification of mechanical harvesting (juice adhering, berries lost, damage of vineyard transaction by the help of semi-trailer and self-propelled harvesters.

  17. Evaluating the urethral closure mechanism after pelvic organ prolapse surgery

    DEFF Research Database (Denmark)

    Khayyami, Yasmine

    2017-01-01

    . By measuring urethral opening pressure at an abdominal pressure of 50 mmH2O (PO-Abd 50), it is the only method that has succeeded in distinguishing between women with and without SUI. The overall aim of this thesis was to evaluate the urethral closure mechanism before and after anterior and posterior......, the woman has occult SUI. However, only half of all women with occult SUI actually develop de novo SUI postoperatively and therefore, the usefulness of the test has been questioned. Studies investigating how POP reduction and POP surgery affect the urethral closure mechanism have used conventional urethral...... pressure profilometry, a method that has shown wide overlaps in the results of women with and without SUI. Urethral pressure reflectometry (UPR), a method that assesses the urethral closure mechanism by means of acoustic reflectometry, has proven highly reproducible in women with and without SUI...

  18. Rock mechanics models evaluation report: Draft report

    International Nuclear Information System (INIS)

    1985-10-01

    This report documents the evaluation of the thermal and thermomechanical models and codes for repository subsurface design and for design constraint analysis. The evaluation was based on a survey of the thermal and thermomechanical codes and models that are applicable to subsurface design, followed by a Kepner-Tregoe (KT) structured decision analysis of the codes and models. The end result of the KT analysis is a balanced, documented recommendation of the codes and models which are best suited to conceptual subsurface design for the salt repository. The various laws for modeling the creep of rock salt are also reviewed in this report. 37 refs., 1 fig., 7 tabs

  19. Evaluation of epidemiological studies

    International Nuclear Information System (INIS)

    Breckow, J.

    1995-01-01

    The publication is intended for readers with a professional background in radiation protection who are not experts in the field of epidemiology. The potentials and the limits of epidemiology are shown and concepts and terminology of radioepidemilogic studies as well as epidemiology in general are explained, in order to provide the necessary basis for understanding or performing evaluations of epidemiologic studies. (orig./VHE) [de

  20. Kinematic Analysis and Performance Evaluation of Novel PRS Parallel Mechanism

    Science.gov (United States)

    Balaji, K.; Khan, B. Shahul Hamid

    2018-02-01

    In this paper, a 3 DoF (Degree of Freedom) novel PRS (Prismatic-Revolute- Spherical) type parallel mechanisms has been designed and presented. The combination of striaght and arc type linkages for 3 DOF parallel mechanism is introduced for the first time. The performances of the mechanisms are evaluated based on the indices such as Minimum Singular Value (MSV), Condition Number (CN), Local Conditioning Index (LCI), Kinematic Configuration Index (KCI) and Global Conditioning Index (GCI). The overall reachable workspace of all mechanisms are presented. The kinematic measure, dexterity measure and workspace analysis for all the mechanism have been evaluated and compared.

  1. Rock mechanics studies for SMES

    International Nuclear Information System (INIS)

    Haimson, B.C.

    1981-01-01

    Superconducting magnetic energy storage (SMES) systems capable of storing thousands of MWh develop tremendous magnetically induced forces when charged. To prevent rutpure of the magnets these forces must be confined. Bedrock offers a practical and relatively inexpensive magnet containment structure. This paper examines the need for rock mechanics research in connection with the construction and use of SMES rock caverns; the unique problems related to housing superconducting magnets in bedrock; site investigations of granite, quartzite and dolomite deposits in Wisconsin; and cavern design requirements to assure cavern stability and limited deformation under the expected mechanical leads. Recommendations are made for siting SMES caverns

  2. Evaluation of concrete mechanical strength through porosity

    Directory of Open Access Journals (Sweden)

    Olivares, M.

    2004-03-01

    Full Text Available The increasing on voids or pores in any material - if the rest of characteristics remains equal -always causes a decrease in their mechanical strength since the ratio volume/resistant mass is lower Following all these fact a well known conclusion rises: there is a relationship between compacity/porosity and mechanical strengths. The purpose of this research is to establish a new possible correlation between both concrete properties with independence of the proportions, type of cement, size of grain, age, use. etc. So it can be concluded that the results of this research allow the engineer or architect in charge of a restoration or reparation to determine the compression strength of a concrete element. A first step is to determine the porosity through a rather short number of tests. Subsequently, compression strength will be obtained applying just a mathematical formula.

    El aumento de huecos o poros de cualquier material, lo mismo que en otras circunstancias, redunda siempre en una merma de sus resistencias mecánicas, al haber menor volumen-masa resistente. En consecuencia, puede deducirse, que hay una relación entre la compacidad/porosidad y las resistencias mecánicas. En el presente trabajo se estudia una posible correlación entre ambas propiedades del hormigón con independencia de su dosificación, tipo de cemento, granulometría, edad, uso, etc. Las conclusiones obtenidas en la presente investigación permiten al técnico, encargado de una restauración o rehabilitación, determinar la resistencia a compresión de un elemento de hormigón, una vez hallada, de una forma sencilla, la porosidad de una muestra no muy voluminosa, mediante la aplicación de una simple fórmula matemática.

  3. Evaluation of Security Mechanisms for Virtual Organizations

    Science.gov (United States)

    Wu, Jake; Periorellis, Panos

    GOLD project is concerned with dynamic formation and management of virtual organizations in order to exploit market opportunities. The project aims to deliver the enabling technology to support the full lifecycle of such VOs. A set of middleware technologies have been designed and implemented to address issues such as trust, security, contract management, monitoring and information management for virtual collaboration between companies. In this paper we will showcase some of the more general requirements for authentication and authorization in GOLD VOs. In conjunction with these requirements we evaluate some of the more popular tools that are currently available in dealing with these issues, together with our own approach in addressing these problems.

  4. Radiolysis: an efficient method of studying radicalar antioxidant mechanisms

    International Nuclear Information System (INIS)

    Gardes-Albert, M.; Jore, D.

    1998-01-01

    The use of the radiolysis method for studying radicalar antioxidant mechanisms offers the different following possibilities: 1- quantitative evaluation of antioxidant activity of molecules soluble in aqueous or non aqueous media (oxidation yields, molecular mechanisms, rate constants), 2- evaluation of the yield of prevention towards polyunsaturated fatty acids peroxidation, 3- evaluation of antioxidant activity towards biological systems such as liposomes or low density lipoproteins (LDL), 4- simple comparison in different model systems of drags effect versus natural antioxidants. (authors)

  5. Mechanical evaluation of space closure loops in Orthodontics

    OpenAIRE

    Rodrigues, Eduardo Uggeri; Maruo, Hiroshi; Guariza Filho, Odilon; Tanaka, Orlando; Camargo, Elisa Souza

    2011-01-01

    This study evaluated the mechanical performance of teardrop-shaped loops and teardrop-shaped loops with helix used in orthodontic space closure. Sixty retraction loops made with 0.019" x 0.025" stainless steel (SS) and beta-titanium (BT) wires were used. They were attached to a testing machine to measure the magnitudes of the sagittal force and the load-deflection ratio necessary for 1 mm, 2 mm and 3 mm activation. The results demonstrated that the BT alloy presented significantly smaller mea...

  6. Evaluation and mechanism for outcomes exploration of providing public health care in contract service in rural China: a multiple-case study with complex adaptive systems design.

    Science.gov (United States)

    Zhou, Huixuan; Zhang, Shengfa; Zhang, Weijun; Wang, Fugang; Zhong, You; Gu, Linni; Qu, Zhiyong; Tian, Donghua

    2015-02-27

    The Chinese government has increased the funding for public health in 2009 and experimentally applied a contract service policy (could be seen as a counterpart to family medicine) in 15 counties to promote public health services in the rural areas in 2013. The contract service aimed to convert village doctors, who had privately practiced for decades, into general practitioners under the government management, and better control the rampant chronic diseases. This study made a rare attempt to assess the effectiveness of public health services delivered under the contract service policy, explore the influencing mechanism and draw the implications for the policy extension in the future. Three pilot counties and a non-pilot one with heterogeneity in economic and health development from east to west of China were selected by a purposive sampling method. The case study methods by document collection, non-participant observation and interviews (including key informant interview and focus group interview) with 84 health providers and 20 demanders in multiple level were applied in this study. A thematic approach was used to compare diverse outcomes and analyze mechanism in the complex adaptive systems framework. Without sufficient incentives, the public health services were not conducted effectively, regardless of the implementation of the contract policy. To appropriately increase the funding for public health by local finance and properly allocate subsidy to village doctors was one of the most effective approaches to stimulate health providers and demanders' positivity and promote the policy implementation. County health bureaus acted as the most crucial agents among the complex public health systems. Their mental models influenced by the compound and various environments around them led to the diverse outcomes. If they could provide extra incentives and make the contexts of the systems ripe enough for change, the health providers and demanders would be receptive to the

  7. Scanning electron microscopic evaluation of the influence of manual and mechanical glide path on the surface of nickel-titanium rotary instruments in moderately curved root canals: An in-vivo study

    Science.gov (United States)

    Patel, Dishant; Bashetty, Kusum; Srirekha, A.; Archana, S.; Savitha, B.; Vijay, R.

    2016-01-01

    Aim: The aim of this study was to evaluate the influence of manual versus mechanical glide path (GP) on the surface changes of two different nickel-titanium rotary instruments used during root canal therapy in a moderately curved root canal. Materials and Methods: Sixty systemically healthy controls were selected for the study. Controls were divided randomly into four groups: Group 1: Manual GP followed by RaCe rotary instruments, Group 2: Manual GP followed by HyFlex rotary instruments, Group 3: Mechanical GP followed by RaCe rotary instruments, Group 4: Mechanical GP followed by HyFlex rotary instruments. After access opening, GP was prepared and rotary instruments were used according to manufacturer's instructions. All instruments were evaluated for defects under standard error mean before their use and after a single use. The scorings for the files were given at apical and middle third. Statistical Analysis Used: Chi-squared test was used. Results: The results showed that there is no statistical difference between any of the groups. Irrespective of the GP and rotary files used, more defects were present in the apical third when compared to middle third of the rotary instrument. Conclusion: Within the limitations of this study, it can be concluded that there was no effect of manual or mechanical GP on surface defects of subsequent rotary file system used. PMID:27994317

  8. Evaluation of a computerized system for mechanical ventilation of infants.

    Science.gov (United States)

    Tehrani, Fleur T; Abbasi, Soraya

    2009-04-01

    To evaluate a computerized system for mechanical ventilation of infants. FLEX is a computerized system that includes the features of a patented mode known as adaptive-support ventilation (ASV). In addition, it has many other features including adjustment of positive end-expiratory pressure (PEEP), fraction of inspired oxygen (F(IO2)), minute ventilation, and control of weaning. It is used as an open-loop decision support system or as a closed-loop technique. Blood gas and ventilation data were collected from 12 infants in the neonatal intensive care at baseline and at the next round of evaluation. This data were input to open-loop version of FLEX. The system recommendations were compared to clinical determinations. FLEX recommended values for ventilation were on the average within 25% and 16.5% of the measured values at baseline and at the next round of evaluation, respectively. For F(IO2) and PEEP, FLEX recommended values were in general agreement with the clinical settings. FLEX recommendations for weaning were the same as the clinical determinations 50% of the time at baseline and 55% of the time at the next round of evaluation. FLEX did not recommend weaning for infants with weak spontaneous breathing effort or those who showed signs of dyspnea. A computerized system for mechanical ventilation is evaluated for treatment of infants. The results of the study show that the system has good potential for use in neonatal ventilatory care. Further refinements can be made in the system for very low-birth-weight infants.

  9. Mechanical property evaluation of natural fiber coir composite

    International Nuclear Information System (INIS)

    Harish, S.; Michael, D. Peter; Bensely, A.; Lal, D. Mohan; Rajadurai, A.

    2009-01-01

    The fiber which serves as a reinforcement in reinforced plastics may be synthetic or natural. Past studies show that only artificial fibers such as glass, carbon etc., have been used in fiber-reinforced plastics. Although glass and other synthetic fiber-reinforced plastics possess high specific strength, their fields of application are very limited because of their inherent higher cost of production. In this connection, an investigation has been carried out to make use of coir, a natural fiber abundantly available in India. Natural fibers are not only strong and lightweight but also relatively very cheap. In the present work, coir composites are developed and their mechanical properties are evaluated. Scanning electron micrographs obtained from fractured surfaces were used for a qualitative evaluation of the interfacial properties of coir/epoxy and compared with glass fiber/epoxy. These results indicate that coir can be used as a potential reinforcing material for making low load bearing thermoplastic composites

  10. Enhancing anaerobic digestion of waste activated sludge by the combined use of NaOH and Mg(OH)2: Performance evaluation and mechanism study.

    Science.gov (United States)

    Huang, Cheng; Lai, Jia; Sun, Xiuyun; Li, Jiansheng; Shen, Jinyou; Han, Weiqing; Wang, Lianjun

    2016-11-01

    In this study, the combination treatment of NaOH and Mg(OH)2 was applied to anaerobic digestion of waste activated sludge (WAS) for simultaneously enhancement of volatile fatty acids (VFAs) production, nutrients removal and sludge dewaterability. The maximum VFAs production (461mg COD/g VSS) was obtained at the NaOH/Mg(OH)2 ratio of 75:25, which was much higher than that of the blank or sole NaOH. Moreover, nutrients removal and sludge dewaterability were improved by the combined using of NaOH and Mg(OH)2. Mechanism investigations revealed that the presence of Mg(OH)2 could maintain alkaline environment, which contributed to inhibit the activity of methanogens. Also, the bridging between Mg(2+) and extracellular polymeric substances (EPS) plays an important role in the solubilization and dewatering of sludge. High-throughput sequencing analysis demonstrated that the abundance of bacteria involved in sludge hydrolysis and VFAs accumulation was greatly enriched with the mixtures of NaOH and Mg(OH)2. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Study of mechanically activated coal combustion

    Directory of Open Access Journals (Sweden)

    Burdukov Anatolij P.

    2009-01-01

    Full Text Available Combustion and air gasification of mechanically activated micro-ground coals in the flux have been studied. Influence of mechanically activated methods at coals grinding on their chemical activeness at combustion and gasification has been determined. Intense mechanical activation of coals increases their chemical activeness that enables development of new highly boosted processing methods for coals with various levels of metamorphism.

  12. Comparative evaluation of insertion torque and mechanical stability for self-tapping and self-drilling orthodontic miniscrews - an in vitro study.

    Science.gov (United States)

    Tepedino, Michele; Masedu, Francesco; Chimenti, Claudio

    2017-05-30

    The aim of the present study was to evaluate the relationship between insertion torque and stability of miniscrews in terms of resistance against dislocation, then comparing a self-tapping screw with a self-drilling one. Insertion torque was measured during placement of 30 self-drilling and 31 self-tapping stainless steel miniscrews (Leone SpA, Sesto Fiorentino, Italy) in synthetic bone blocks. Then, an increasing pulling force was applied at an angle of 90° and 45°, and the displacement of the miniscrews was recorded. The statistical analysis showed a statistically significant difference between the mean Maximum Insertion Torque (MIT) observed in the two groups and showed that force angulation and MIT have a statistically significant effect on miniscrews stability. For both the miniscrews, an angle of 90° between miniscrew and loading force is preferable in terms of stability. The tested self-drilling orthodontic miniscrews showed higher MIT and greater resistance against dislocation than the self-tapping ones.

  13. Long term study of mechanical

    Directory of Open Access Journals (Sweden)

    Ahmed M. Diab

    2016-06-01

    Full Text Available In this study, properties of limestone cement concrete containing different replacement levels of limestone powder were examined. It includes 0%, 5%, 10%, 15%, 20% and 25% of limestone powder as a partial replacement of cement. Silica fume was added incorporated with limestone powder in some mixes to enhance the concrete properties. Compressive strength, splitting tensile strength and modulus of elasticity were determined. Also, durability of limestone cement concrete with different C3A contents was examined. The weight loss, length change and cube compressive strength loss were measured for concrete attacked by 5% sodium sulfate using an accelerated test up to 525 days age. The corrosion resistance was measured through accelerated corrosion test using first crack time, cracking width and steel reinforcement weight loss. Consequently, for short and long term, the use of limestone up to 10% had not a significant reduction in concrete properties. It is not recommended to use blended limestone cement in case of sulfate attack. The use of limestone cement containing up to 25% limestone has insignificant effect on corrosion resistance before cracking.

  14. 3D-printing zirconia implants; a dream or a reality? An in-vitro study evaluating the dimensional accuracy, surface topography and mechanical properties of printed zirconia implant and discs.

    Science.gov (United States)

    Osman, Reham B; van der Veen, Albert J; Huiberts, Dennis; Wismeijer, Daniel; Alharbi, Nawal

    2017-11-01

    The aim of this study was to evaluate the dimensional accuracy, surface topography of a custom designed, 3D-printed zirconia dental implant and the mechanical properties of printed zirconia discs. A custom designed implant was 3D-printed in zirconia using digital light processing technique (DLP). The dimensional accuracy was assessed using the digital-subtraction technique. The mechanical properties were evaluated using biaxial flexure strength test. Three different build angles were adopted to print the specimens for the mechanical test; 0°(Vertical), 45° (Oblique) and 90°(Horizontal) angles. The surface topography, crystallographic phase structure and surface roughness were evaluated using scanning electron microscopy analysis (SEM), X-ray diffractometer and confocal microscopy respectively. The printed implant was dimensionally accurate with a root mean square (RMSE) value of 0.1mm. The Weibull analysis revealed a statistically significant higher characteristic strength (1006.6MPa) of 0° printed specimens compared to the other two groups and no significant difference between 45° (892.2MPa) and 90° (866.7MPa) build angles. SEM analysis revealed cracks, micro-porosities and interconnected pores ranging in size from 196nm to 3.3µm. The mean Ra (arithmetic mean roughness) value of 1.59µm (±0.41) and Rq (root mean squared roughness) value of 1.94µm (±0.47) was found. A crystallographic phase of primarily tetragonal zirconia typical of sintered Yttria tetragonal stabilized zirconia (Y-TZP) was detected. DLP prove to be efficient for printing customized zirconia dental implants with sufficient dimensional accuracy. The mechanical properties showed flexure strength close to those of conventionally produced ceramics. Optimization of the 3D-printing process parameters is still needed to improve the microstructure of the printed objects. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Designs for mechanical circulatory support device studies.

    Science.gov (United States)

    Neaton, James D; Normand, Sharon-Lise; Gelijns, Annetine; Starling, Randall C; Mann, Douglas L; Konstam, Marvin A

    2007-02-01

    There is increased interest in mechanical circulatory support devices (MCSDs), such as implantable left ventricular assist devices (LVADs), as "destination" therapy for patients with advanced heart failure. Because patient availability to evaluate these devices is limited and randomized trials have been slow in enrolling patients, a workshop was convened to consider designs for MCSD development including alternatives to randomized trials. A workshop was jointly planned by the Heart Failure Society of America and the US Food and Drug Administration and was convened in March 2006. One of the panels was asked to review different designs for evaluating new MCSDs. Randomized trials have many advantages over studies with no controls or with nonrandomized concurrent or historical controls. These advantages include the elimination of bias in the assignment of treatments and the balancing, on average, of known and unknown baseline covariates that influence response. These advantages of randomization are particularly important for studies in which the treatments may not differ from one another by a large amount (eg, a head-to-head study of an approved LVAD with a new LVAD). However, researchers have found it difficult to recruit patients to randomized studies because the number of clinical sites that can carry out the studies is not large. Also, there is a reluctance to randomize patients when the control device is considered technologically inferior. Thus ways of improving the design of randomized trials were discussed, and the advantages and disadvantages of alternative designs were considered. The panel concluded that designs should include a randomized component. Randomized designs might be improved by allowing the control device to be chosen before randomization, by first conducting smaller vanguard studies, and by allowing crossovers in trials with optimal medical management controls. With use of data from completed trials, other databases, and registries, alternative

  16. Crowdsourcing Participatory Evaluation of Medical Pictograms Using Amazon Mechanical Turk

    OpenAIRE

    Yu, Bei; Willis, Matt; Sun, Peiyuan; Wang, Jun

    2013-01-01

    Background Consumer and patient participation proved to be an effective approach for medical pictogram design, but it can be costly and time-consuming. We proposed and evaluated an inexpensive approach that crowdsourced the pictogram evaluation task to Amazon Mechanical Turk (MTurk) workers, who are usually referred to as the ?turkers?. Objective To answer two research questions: (1) Is the turkers? collective effort effective for identifying design problems in medical pictograms? and (2) Do ...

  17. Nuclear plant components: mechanical analysis and lifetime evaluation

    International Nuclear Information System (INIS)

    Chator, T.

    1993-09-01

    This paper concerns the methodology adopted by the Research and Development Division to handle mechanical problems found in structures and machines. Usually, these often very complex studies (3-D structures, complex loadings, non linear behavior laws) call for advanced tools and calculation means. In order to do these complex studies, R and D Division is developing a software. It handles very complex thermo-mechanical analysis using the Finite Element Method. It enables us to analyse static, dynamic, elasto-plastic problems as well as contact problems or evaluating damage and lifetime of structures. This paper will be illustrated by actual industrial case examples. The major ones will be dealing with: 1. Analysis of a new impeller/shaft assembly of a primary coolant pump. The 3D meshing is submitted simultaneously to thermal load, pressure, hydraulic, centrifugal and axial forces and clamping of studs; contacts between shaft/impeller, nuts bearing side/shaft bearing side. For this study, we have developed a new method to handle the clamping of studs. The stud elongation value is given into the software which automatically computes the distorsions between both the structures in contact and then the final position of bearing areas (using an iterative non-linear algorithm of modified Newton-Raphson type). 2. Analysis of the stress intensity factor of crack. The 3D meshing (representing the crack) is submitted simultaneously to axial and radial forces. In this case, we use the Theta method to calculate the energy restitution rate in order to determine the stress intensity factors. (authors). 7 figs., 1 tab., 3 refs

  18. In vitro mechanical evaluation of a novel pin-sleeve system for external fixation of distal limb fractures in horses: a proof of concept study.

    Science.gov (United States)

    Brianza, Stefano; Brighenti, Vittoria; Boure, Ludovic; Sprenger, Victor; Pearce, Simon; Schwieger, Karsten

    2010-07-01

    To evaluate the efficacy of a novel pin-sleeve cast (PSC) system for external fixation of distal limb fractures in horses and to compare it with the transfixation pin cast (TPC) system. Experimental. One bone substitute each was used for the TPC and PSC systems. The PSC was tested in 4 configurations characterized by different pin preloads. Specimens were loaded in axial compression in the elastic range. Variables compared statistically were: bone substitute axial displacement and axial strain measured above implants with strain gauges. Pin preload was correlated with the variables investigated. Load to failure and a fatigue tests supplemented the investigation. The PSC configuration with the highest pin preload showed a significantly lower axial displacement compared with the TPC. No significant differences were observed between all other PSC configurations and the TPC. All PSC systems had a significant decrease in recorded strain compared with the TPC system. Pin axial preload inversely correlated with axial displacement but had no effect on axial strain. In the failure test, the PSC encountered plastic deformation earlier than the TPC. In the fatigue test, the PSC ran >200,000 cycles. Preliminary in vitro tests showed that the PSC system significantly reduced peri-implant strain while concurrently having comparable axial displacement to the TPC system. The PSC system has the potential to reduce the risk of pin loosening in horses.

  19. Physiological evaluation of a newly designed lever mechanism for wheelchairs

    NARCIS (Netherlands)

    van der Woude, L H; Veeger, DirkJan (H. E. J.); de Boer, Y; Rozendal, R H

    1993-01-01

    Lever-propelled wheelchairs have been described as more efficient and less physically demanding than hand-rim-propelled wheelchairs. To evaluate a newly designed lever mechanism (MARC) in both one- and two-arm use, a series of wheelchair exercise tests were performed on a motor-driven treadmill.

  20. Evaluation of the mechanical and physical properties of a posterior ...

    African Journals Online (AJOL)

    To evaluate the mechanical and physical properties of a micro-hybrid resin composite used in adult posterior restorations A micro-hybrid, light curing resin composite Unolux BCS Composite Restorative, (UnoDent, England) was used to restore 74 carious classes I and II cavities on posterior teeth of 62 adult patients.

  1. Mechanism study of pulsus paradoxus using mechanical models.

    Directory of Open Access Journals (Sweden)

    Chang-yang Xing

    Full Text Available Pulsus paradoxus is an exaggeration of the normal inspiratory decrease in systolic blood pressure. Despite a century of attempts to explain this sign consensus is still lacking. To solve the controversy and reveal the exact mechanism, we reexamined the characteristic anatomic arrangement of the circulation system in the chest and designed these mechanical models based on related hydromechanic principles. Model 1 was designed to observe the primary influence of respiratory intrathoracic pressure change (RIPC on systemic and pulmonary venous return systems (SVR and PVR respectively. Model 2, as an equivalent mechanical model of septal swing, was to study the secondary influence of RIPC on the motion of the interventriclar septum (IVS, which might be the direct cause for pulsus paradoxus. Model 1 demonstrated that the simulated RIPC had different influence on the simulated SVR and PVR. It increased the volume of the simulated right ventricle (SRV when the internal pressure was kept constant (8.16 cmH2O, while it had the opposite effect on PVR. Model 2 revealed the three major factors determining the respiratory displacement of IVS in normal and different pathophysiological conditions: the magnitude of RIPC, the pressure difference between the two ventricles and the intrapericardial pressure. Our models demonstrate that the different anatomical arrangement of the two venous return systems leads to a different effect of RIPC on right and left ventricles, and thus a pressure gradient across IVS that tends to shift IVS left- and rightwards. When the leftward displacement of IVS reaches a considerable amplitude in some pathologic condition such as cardiac tamponade, the pulsus paradoxus occurs.

  2. Fracture mechanics evaluation for at typical PWR primary coolant pipe

    International Nuclear Information System (INIS)

    Tanaka, T.; Shimizu, S.; Ogata, Y.

    1997-01-01

    For the primary coolant piping of PWRs in Japan, cast duplex stainless steel which is excellent in terms of strength, corrosion resistance, and weldability has conventionally been used. The cast duplex stainless steel contains the ferrite phase in the austenite matrix and thermal aging after long term service is known to change its material characteristics. It is considered appropriate to apply the methodology of elastic plastic fracture mechanics for an evaluation of the integrity of the primary coolant piping after thermal aging. Therefore we evaluated the integrity of the primary coolant piping for an initial PWR plant in Japan by means of elastic plastic fracture mechanics. The evaluation results show that the crack will not grow into an unstable fracture and the integrity of the piping will be secured, even when such through wall crack length is assumed to equal the fatigue crack growth length for a service period of up to 60 years

  3. Fracture mechanics evaluation for at typical PWR primary coolant pipe

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, T. [Kansai Electric Power Company, Osaka (Japan); Shimizu, S.; Ogata, Y. [Mitsubishi Heavy Industries, Ltd., Kobe (Japan)

    1997-04-01

    For the primary coolant piping of PWRs in Japan, cast duplex stainless steel which is excellent in terms of strength, corrosion resistance, and weldability has conventionally been used. The cast duplex stainless steel contains the ferrite phase in the austenite matrix and thermal aging after long term service is known to change its material characteristics. It is considered appropriate to apply the methodology of elastic plastic fracture mechanics for an evaluation of the integrity of the primary coolant piping after thermal aging. Therefore we evaluated the integrity of the primary coolant piping for an initial PWR plant in Japan by means of elastic plastic fracture mechanics. The evaluation results show that the crack will not grow into an unstable fracture and the integrity of the piping will be secured, even when such through wall crack length is assumed to equal the fatigue crack growth length for a service period of up to 60 years.

  4. Properties of bioadhesive ketoprofen liquid suppositories: preparation, determination of gelation temperature, viscosity studies and evaluation of mechanical properties using texture analyzer by 4 × 4 factorial design.

    Science.gov (United States)

    Ozgüney, Işık; Kardhiqi, Anita

    2014-12-01

    Development and evaluation of thermosensitive and bioadhesive liquid suppositories containing ketoprofen (KP). This study was conducted to develope thermosensitive and bioadhesive liquid suppositories containing KP using poloxamer and different bioadhesive polymers and to investigate their gelation temperature, viscosity and mechanical properties. Bioadhesive liquid suppositories were prepared by the cold method using poloxamer 407 (P 407), Poloxamer 188 (P 188) and various amounts of different bioadhesive polymers. Their gelation temperatures, viscosity values and mechanical properties were determined using texture analyzer by 4 × 4 factorial design. It was seen that in presence of KP, gelation temperature of formulation P 407/P 188 (4/20%) significantly decreased from 64 to 37.1 °C. It is to be noted that addition of increasing concentrations of bioadhesive polymers lowered gelation temperature and its decrease was highest with addition of Carbopol 934 P (C). Results of texture profile analysis (TPA) showed that formulations containing C have significantly higher hardness and adhesiveness values than other bioadhesive formulations. According to TPA, gel structure of liquid suppository formulation F5, containing P 407/P 188/KP/C (4/20/2.5/0.8%), exhibited the greatest hardness, compressibilty, adhesiveness and besides greatest viscosity. According to mechanical properties and viscosity values, it was concluded that F5 could be a promising formulation.

  5. Evaluation on mechanical properties of woven aloevera and sisal ...

    Indian Academy of Sciences (India)

    Administrator

    behaviour of this composite is observed to be more effec- tive.5 The fibre .... been made to study the mechanical properties of woven aloevera and ... In each case, minimum of ... tions in automotive components, structures and consumer goods.

  6. Light water reactors fuel assembly mechanical design and evaluation

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    This standard establishes a procedure for performing an evaluation of the mechanical design of fuel assemblies for light water-cooled commercial power reactors. It does not address the various aspects of neutronic or thermalhydraulic performance except where these factors impose loads or constraints on the mechanical design of the fuel assemblies. This standard also includes a set of specific requirements for design, various potential performance problems and criteria aimed specifically at averting them. This standard replaces ANSI/ANS-57.5-1978

  7. Failure mechanism dependence and reliability evaluation of non-repairable system

    International Nuclear Information System (INIS)

    Chen, Ying; Yang, Liu; Ye, Cui; Kang, Rui

    2015-01-01

    Reliability study of electronic system with the physics-of-failure method has been promoted due to the increase knowledge of electronic failure mechanisms. System failure initiates from independent failure mechanisms, have effect on or affect by other failure mechanisms and finally result in system failure. Failure mechanisms in a non-repairable system have many kinds of correlation. One failure mechanism developing to a certain degree will trigger, accelerate or inhibit another or many other failure mechanisms, some kind of failure mechanisms may have the same effect on the failure site, component or system. The destructive effect will be accumulated and result in early failure. This paper presents a reliability evaluation method considering correlativity among failure mechanisms, which includes trigger, acceleration, inhibition, accumulation, and competition. Based on fundamental rule of physics of failure, decoupling methods of these correlations are discussed. With a case, reliability of electronic system is evaluated considering failure mechanism dependence. - Highlights: • Five types of failure mechanism correlations are described. • Decoupling methods of these correlations are discussed. • A reliability evaluation method considering mechanism dependence is proposed. • Results are quite different to results under failure independence assumption

  8. Mechanical evaluation of space closure loops in orthodontics.

    Science.gov (United States)

    Rodrigues, Eduardo Uggeri; Maruo, Hiroshi; Guariza Filho, Odilon; Tanaka, Orlando; Camargo, Elisa Souza

    2011-01-01

    This study evaluated the mechanical performance of teardrop-shaped loops and teardrop-shaped loops with helix used in orthodontic space closure. Sixty retraction loops made with 0.019" x 0.025" stainless steel (SS) and beta-titanium (BT) wires were used. They were attached to a testing machine to measure the magnitudes of the sagittal force and the load-deflection ratio necessary for 1 mm, 2 mm and 3 mm activation. The results demonstrated that the BT alloy presented significantly smaller mean values (p < 0.01) of sagittal force and load-deflection than the SS alloy. The loop with the highest mean value of sagittal force and load-deflection was the teardrop-shaped loop (p < 0.01). Differences were observed in the mean values of sagittal force and load-deflection among activations, and the highest mean value was found in the activation of 3 mm, while the smallest mean value was evident in the activation of 1 mm (p < 0.01). It could be concluded that the metallic alloy used and the presence of a helix in configuration of the loops may have a strong influence on the sagittal force produced and on the load-deflection ratio; the teardrop-shaped loops and teardrop-shaped loops with helix in BT presented the release of lighter forces; the teardrop-shaped loop in SS generated a high load-deflection ratio, providing high magnitudes of horizontal force during its deactivation.

  9. Menses cup evaluation study.

    Science.gov (United States)

    Cheng, M; Kung, R; Hannah, M; Wilansky, D; Shime, J

    1995-09-01

    To determine whether the menses cup is well tolerated by menstruating women. Prospective descriptive clinical study. Normal human volunteers in an academic research environment. Fifty-one menstruating women recruited between June to December 1991. Each participant was provided with two menses cups and an instruction sheet. Baseline information, including age, occupation, martial status, parity, description of menstrual flow, and current method used to cope with menstrual flow was collected. Subjects were asked to describe their experience with the cup at 1-, 2-, 6-, and 12-month intervals. The proportion of women who found the cup acceptable. The cup was used by 51 subjects for a total of 159 cycles. Overall, 23 women (45%) found the cup an acceptable method for coping with menses. Among 29 (57%) women who used the cup for two or more cycles, 62% found it acceptable. The menses cup may be an acceptable method for some women for coping with menstrual flow.

  10. Quantum Mechanical Studies of DNA and LNA

    DEFF Research Database (Denmark)

    Koch, Troels; Shim, Irene; Lindow, Morten

    2014-01-01

    Quantum mechanical (QM) methodology has been employed to study the structure activity relations of DNA and locked nucleic acid (LNA). The QM calculations provide the basis for construction of molecular structure and electrostatic surface potentials from molecular orbitals. The topologies of the e......Quantum mechanical (QM) methodology has been employed to study the structure activity relations of DNA and locked nucleic acid (LNA). The QM calculations provide the basis for construction of molecular structure and electrostatic surface potentials from molecular orbitals. The topologies...

  11. Evaluating mechanical properties and degradation of YTZP dental implants

    International Nuclear Information System (INIS)

    Sevilla, Pablo; Sandino, Clara; Arciniegas, Milena; Martinez-Gomis, Jordi; Peraire, Maria; Gil, Francisco Javier

    2010-01-01

    Lately new biomedical grade yttria stabilized zirconia (YTZP) dental implants have appeared in the implantology market. This material has better aesthetical properties than conventional titanium used for implants but long term behaviour of these new implants is not yet well known. The aim of this paper is to quantify the mechanical response of YTZP dental implants previously degraded under different time conditions and compare the toughness and fatigue strength with titanium implants. Mechanical response has been studied by means of mechanical testing following the ISO 14801 for Standards for dental implants and by finite element analysis. Accelerated hydrothermal degradation has been achieved by means of water vapour and studied by X-ray diffraction and nanoindentation tests. The results show that the degradation suffered by YTZP dental implants will not have a significant effect on the mechanical behaviour. Otherwise the fracture toughness of YTZP ceramics is still insufficient in certain implantation conditions.

  12. Crowdsourcing participatory evaluation of medical pictograms using Amazon Mechanical Turk.

    Science.gov (United States)

    Yu, Bei; Willis, Matt; Sun, Peiyuan; Wang, Jun

    2013-06-03

    Consumer and patient participation proved to be an effective approach for medical pictogram design, but it can be costly and time-consuming. We proposed and evaluated an inexpensive approach that crowdsourced the pictogram evaluation task to Amazon Mechanical Turk (MTurk) workers, who are usually referred to as the "turkers". To answer two research questions: (1) Is the turkers' collective effort effective for identifying design problems in medical pictograms? and (2) Do the turkers' demographic characteristics affect their performance in medical pictogram comprehension? We designed a Web-based survey (open-ended tests) to ask 100 US turkers to type in their guesses of the meaning of 20 US pharmacopeial pictograms. Two judges independently coded the turkers' guesses into four categories: correct, partially correct, wrong, and completely wrong. The comprehensibility of a pictogram was measured by the percentage of correct guesses, with each partially correct guess counted as 0.5 correct. We then conducted a content analysis on the turkers' interpretations to identify misunderstandings and assess whether the misunderstandings were common. We also conducted a statistical analysis to examine the relationship between turkers' demographic characteristics and their pictogram comprehension performance. The survey was completed within 3 days of our posting the task to the MTurk, and the collected data are publicly available in the multimedia appendix for download. The comprehensibility for the 20 tested pictograms ranged from 45% to 98%, with an average of 72.5%. The comprehensibility scores of 10 pictograms were strongly correlated to the scores of the same pictograms reported in another study that used oral response-based open-ended testing with local people. The turkers' misinterpretations shared common errors that exposed design problems in the pictograms. Participant performance was positively correlated with their educational level. The results confirmed that

  13. Evaluating the reliability of multi-body mechanisms: A method considering the uncertainties of dynamic performance

    International Nuclear Information System (INIS)

    Wu, Jianing; Yan, Shaoze; Zuo, Ming J.

    2016-01-01

    Mechanism reliability is defined as the ability of a certain mechanism to maintain output accuracy under specified conditions. Mechanism reliability is generally assessed by the classical direct probability method (DPM) derived from the first order second moment (FOSM) method. The DPM relies strongly on the analytical form of the dynamic solution so it is not applicable to multi-body mechanisms that have only numerical solutions. In this paper, an indirect probability model (IPM) is proposed for mechanism reliability evaluation of multi-body mechanisms. IPM combines the dynamic equation, degradation function and Kaplan–Meier estimator to evaluate mechanism reliability comprehensively. Furthermore, to reduce the amount of computation in practical applications, the IPM is simplified into the indirect probability step model (IPSM). A case study of a crank–slider mechanism with clearance is investigated. Results show that relative errors between the theoretical and experimental results of mechanism reliability are less than 5%, demonstrating the effectiveness of the proposed method. - Highlights: • An indirect probability model (IPM) is proposed for mechanism reliability evaluation. • The dynamic equation, degradation function and Kaplan–Meier estimator are used. • Then the simplified form of indirect probability model is proposed. • The experimental results agree well with the predicted results.

  14. Ultrasonic evaluation of the physical and mechanical properties of granites.

    Science.gov (United States)

    Vasconcelos, G; Lourenço, P B; Alves, C A S; Pamplona, J

    2008-09-01

    Masonry is the oldest building material that survived until today, being used all over the world and being present in the most impressive historical structures as an evidence of spirit of enterprise of ancient cultures. Conservation, rehabilitation and strengthening of the built heritage and protection of human lives are clear demands of modern societies. In this process, the use of nondestructive methods has become much common in the diagnosis of structural integrity of masonry elements. With respect to the evaluation of the stone condition, the ultrasonic pulse velocity is a simple and economical tool. Thus, the central issue of the present paper concerns the evaluation of the suitability of the ultrasonic pulse velocity method for describing the mechanical and physical properties of granites (range size between 0.1-4.0 mm and 0.3-16.5 mm) and for the assessment of its weathering state. The mechanical properties encompass the compressive and tensile strength and modulus of elasticity, and the physical properties include the density and porosity. For this purpose, measurements of the longitudinal ultrasonic pulse velocity with distinct natural frequency of the transducers were carried out on specimens with different size and shape. A discussion of the factors that induce variations on the ultrasonic velocity is also provided. Additionally, statistical correlations between ultrasonic pulse velocity and mechanical and physical properties of granites are presented and discussed. The major output of the work is the confirmation that ultrasonic pulse velocity can be effectively used as a simple and economical nondestructive method for a preliminary prediction of mechanical and physical properties, as well as a tool for the assessment of the weathering changes of granites that occur during the serviceable life. This is of much interest due to the usual difficulties in removing specimens for mechanical characterization.

  15. Evaluation of binding energies by using quantum mechanical methods

    International Nuclear Information System (INIS)

    Postolache, Cristian; Matei, Lidia; Postolache, Carmen

    2002-01-01

    Evaluation of binding energies (BE) in molecular structure is needed for modelling chemical and radiochemical processes by quantum-chemical methods. An important field of application is evaluation of radiolysis and autoradiolysis stability of organic and inorganic compounds as well as macromolecular structures. The current methods of calculation do not allow direct determination of BE but only of total binding energies (TBE) and enthalpies. BEs were evaluated indirectly by determining the homolytic dissociation energies. The molecular structures were built and geometrically optimized by the molecular mechanics methods MM+ and AMBER. The energy minimizations were refined by semi-empirical methods. Depending on the chosen molecular structure, the CNDO, INDO, PM3 and AM1 methods were used. To reach a high confidence level the minimizations were done for gradients lower than 10 -3 RMS. The energy values obtained by the difference of the fragment TBLs, of the transition states and initial molecular structures, respectively, were associated to the hemolytic fragmentation energy and BE, respectively. In order to evaluate the method's accuracy and to establish the application fields of the evaluation methods, the obtained values of BEs were compared with the experimental data taken from literature. To this goal there were built, geometrically optimized by semi-empirical methods and evaluated the BEs for 74 organic and inorganic compounds (alkanes, alkene, alkynes, halogenated derivatives, alcohols, aldehydes, ketones, carboxylic acids, nitrogen and sulfur compounds, water, hydrogen peroxide, ammonia, hydrazine, etc. (authors)

  16. Post design evaluation (ageing mechanisms, effects, management, monitoring, PSR, ISI)

    International Nuclear Information System (INIS)

    Ichikawa, Toshio

    2001-01-01

    Although the nuclear plant was designed for the purpose of the 30-year life the early stages of construction, it also already has the plant abolished by passing in 30 years. There is a plant under operation and a plant that is employed variously, extends the original life and continues operation now, and the plant that is going to be abolished politically is before a life. By using a nuclear plant for a long period of time, damage. by the influence of irradiation, wear of slipping, corrosion, etc. appears. When this degradation is left, the serious accident is caused. In this lecture, refer to Assessment and management of ageing of major nuclear power plant components important to safety, Oct. 1999 of IAEA. A point of view from guide is introduced about management of the mechanism in the secular degradation mode expected by operating for a long period of time, the influence of secular degradation, and influence, monitoring technology, periodical safe evaluation, and a periodic inspection. And raises and explains the correspondence situation of secular degradation, and the example of evaluation of PSR and ISI equipment. The aging mechanism for reactor vessel internal components considered are related to embrittlement, fatigue, corrosion, radiation induced creep, relaxation and swelling, and mechanical wear. This lecture includes; monitoring methods, a description of periodic safety reviews and a sample of seismic design periodic safety report for the reactor internals

  17. Laboratory Studies of Hydrocarbon Oxidation Mechanisms

    Science.gov (United States)

    Orlando, J. J.; Tyndall, G. S.; Wallington, T. J.; Burkholder, J. B.; Bertman, S. B.; Chen, W.

    2001-12-01

    The oxidation of hydrocarbon species (alkanes, alkenes, halogenated species, and oxygenates of both natural and anthropogenic origin) in the troposphere leads to the generation of numerous potentially harmful secondary pollutants, such as ozone, organic nitrates and acids, and aerosols. These oxidations proceed via the formation of alkoxy radicals, whose complex chemistry controls the ultimate product distributions obtained. Studies of hydrocarbon oxidation mechanisms are ongoing at NCAR and Ford, using environmental chamber / FTIR absorption systems. The focus of these studies is often on the product distributions obtained at low temperature; these studies not only provide data of direct relevance to the free/upper troposphere, but also allow for a more fundamental understanding of the alkoxy radical chemistry (eg., from the determination of the Arrhenius parameters for unimolecular processes, and the quantification of the extent of the involvement of chemical activation in the alkoxy radical chemistry). In this paper, data will be presented on some or all of the following topics: kinetics/mechanisms for the reactions of OH with the unsaturated species MPAN, acrolein, and crotonaldehyde; the mechanism for the oxidation of ethyl chloride and ethyl bromide; and the mechanism for the reaction of OH with acetone and acetaldehyde at low temperature. The relevance of the data to various aspects of tropospheric chemistry will be discussed.

  18. Mechanical evaluation of space closure loops in Orthodontics

    Directory of Open Access Journals (Sweden)

    Eduardo Uggeri Rodrigues

    2011-02-01

    Full Text Available This study evaluated the mechanical performance of teardrop-shaped loops and teardrop-shaped loops with helix used in orthodontic space closure. Sixty retraction loops made with 0.019" x 0.025" stainless steel (SS and beta-titanium (BT wires were used. They were attached to a testing machine to measure the magnitudes of the sagittal force and the load-deflection ratio necessary for 1 mm, 2 mm and 3 mm activation. The results demonstrated that the BT alloy presented significantly smaller mean values (p < 0.01 of sagittal force and load-deflection than the SS alloy. The loop with the highest mean value of sagittal force and load-deflection was the teardrop-shaped loop (p < 0.01. Differences were observed in the mean values of sagittal force and load-deflection among activations, and the highest mean value was found in the activation of 3 mm, while the smallest mean value was evident in the activation of 1 mm (p < 0.01. It could be concluded that the metallic alloy used and the presence of a helix in configuration of the loops may have a strong influence on the sagittal force produced and on the load-deflection ratio; the teardrop-shaped loops and teardrop-shaped loops with helix in BT presented the release of lighter forces; the teardrop-shaped loop in SS generated a high load-deflection ratio, providing high magnitudes of horizontal force during its deactivation.

  19. Evaluation of reduced chemical kinetic mechanisms used for modeling mild combustion for natural gas

    Directory of Open Access Journals (Sweden)

    Hamdi Mohamed

    2009-01-01

    Full Text Available A numerical and parametric study was performed to evaluate the potential of reduced chemistry mechanisms to model natural gas chemistry including NOx chemistry under mild combustion mode. Two reduced mechanisms, 5-step and 9-step, were tested against the GRI-Mech3.0 by comparing key species, such as NOx, CO2 and CO, and gas temperature predictions in idealized reactors codes under mild combustion conditions. It is thus concluded that the 9-step mechanism appears to be a promising reduced mechanism that can be used in multi-dimensional codes for modeling mild combustion of natural gas.

  20. EIA and EINP. Evaluation study

    International Nuclear Information System (INIS)

    Lande, R.W.I. van der; De Vries, E.F.

    2001-01-01

    The evaluation study on the title subjects concerns two subsidy tools in the Netherlands: the Energy Investment Rebate (EIA, abbreviated in Dutch) and the Subsidy for Energy in the non-profit sector and other special sectors (EINP, abbreviated in Dutch). The central question in the evaluation was to what extent did the EIA and EINP contribute to the original policy targets and at what costs. The evaluation has been carried out by means of a desk study, interviews, and an analysis of bottlenecks and possible solutions. [nl

  1. Comparative Evaluation of Tactile Sensation by Electrical and Mechanical Stimulation.

    Science.gov (United States)

    Yem, Vibol; Kajimoto, Hiroyuki

    2017-01-01

    An electrotactile display is a tactile interface that provides tactile perception by passing electrical current through the surface of the skin. It is actively used instead of mechanical tactile displays for tactile feedback because of several advantages such as its small and thin size, light weight, and high responsiveness. However, the similarities and differences between these sensations is still not clear. This study directly compares the intensity sensation of electrotactile stimulation to that of mechanical stimulation, and investigates the characteristic sensation of anodic and cathodic stimulation. In the experiment, participants underwent a 30 pps electrotactile stimulus every one second to their middle finger, and were asked to match this intensity by adjusting the intensity of a mechanical tactile stimulus to an index finger. The results showed that anodic stimulation mainly produced vibration sensation, whereas cathodic sensation produced both vibration and pressure sensations. Relatively low pressure sensation was also observed for anodic stimulation but it remains low, regardless of the increasing of electrical intensity.

  2. Fracture mechanical evaluation of high temperature structure and creep-fatigue defect assessment

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chang Gyu; Kim, Jong Bum; Lee, Jae Han

    2004-02-01

    This study proposed the evaluation procedure of high temperature structures from the viewpoint of fracture mechanics on the cylindrical structure applicable to the KALIMER, which is developed by KAERI. For the evaluation of structural integrity, linear and non-linear fracture mechanics parameters were analyzed. Parameters used in creep defect growth applicable to high temperature structure of liquid metal reactor and the evaluation codes with these parameters were analyzed. The evaluation methods of defect initiation and defect growth which were established in R5/R6 code(UK), JNC method (Japan) and RCC-MR A16(France) code were analyzed respectively. The evaluation procedure of leak before break applicable to KALIMER was preliminarily developed and proposed. As an application example of defect growth, the creep-fatigue defect growth on circumferential throughwall defect in high temperature cylindrical structure was evaluated by RCC-MR A16 and this application technology was established.

  3. Maintainability design and evaluation of mechanical systems based on tribology

    International Nuclear Information System (INIS)

    Wani, M.F.; Gandhi, O.P.

    2002-01-01

    Maintainability of mechanical systems based on tribology is suggested and evaluated in this paper. Tribo-features of mechanical systems, which characterise maintainability are identified and are modelled in terms of tribo-maintainability digraph. The nodes in the digraph represent the tribo-features and edges represent the degree of influence among the features. A matrix, one to one representation of the digraph, is defined to develop system maintainability expression (SPF-t) based on the tribology. It is also useful in comparing the various design alternatives from tribo-maintainability point of view. Maintainability is evaluated from the tribo-maintainability index, obtained from SPF-t (i.e. permanent of the matrix) by substituting the numerical values of the features and their interdependence. A higher value of the index implies better maintainability of the systems. The proposed methodology also guides designers in enhancing the maintainability of a system by appropriately incorporating tribo-features. An example to illustrate the methodology is also presented

  4. Evaluation of geophysical borehole studies

    International Nuclear Information System (INIS)

    Brotzen, O.; Duran, O.; Magnusson, K.Aa.

    Four studies concerning geophysical investigations and TV inspection in boreholes in connection with KBS studies at Finnsjoe, Karlshamn, Kraakemaala and Stripa and PRAV's studies at Studsvik have been evaluated. This has led to proposals concerning the choice of instruments and methods for future studies and a review of future work required. The evaluation has shown that the following borehole measurements are of primary interest in the continued work: Determinations of temperature and resistivity of the borehole liquid, resistance and resistivity measurements, SP, Sonic, Caliper and VLF. TV inspection, IP and gamma-gamma should also be included in the arsenal of available test methods.(author)

  5. Pulmonary Mechanics and Mortality in Mechanically Ventilated Patients Without Acute Respiratory Distress Syndrome: A Cohort Study.

    Science.gov (United States)

    Fuller, Brian M; Page, David; Stephens, Robert J; Roberts, Brian W; Drewry, Anne M; Ablordeppey, Enyo; Mohr, Nicholas M; Kollef, Marin H

    2018-03-01

    Driving pressure has been proposed as a major determinant of outcome in patients with acute respiratory distress syndrome (ARDS), but there is little data examining the association between pulmonary mechanics, including driving pressure, and outcomes in mechanically ventilated patients without ARDS. Secondary analysis from 1,705 mechanically ventilated patients enrolled in a clinical study that examined outcomes associated with the use of early lung-protective mechanical ventilation. The primary outcome was mortality and the secondary outcome was the incidence of ARDS. Multivariable models were constructed to: define the association between pulmonary mechanics (driving pressure, plateau pressure, and compliance) and mortality; and evaluate if driving pressure contributed information beyond that provided by other pulmonary mechanics. The mortality rate for the entire cohort was 26.0%. Compared with survivors, non-survivors had significantly higher driving pressure [15.9 (5.4) vs. 14.9 (4.4), P = 0.005] and plateau pressure [21.4 (5.7) vs. 20.4 (4.6), P = 0.001]. Driving pressure was independently associated with mortality [adjusted OR, 1.04 (1.01-1.07)]. Models related to plateau pressure also revealed an independent association with mortality, with similar effect size and interval estimates as driving pressure. There were 152 patients who progressed to ARDS (8.9%). Along with driving pressure and plateau pressure, mechanical power [adjusted OR, 1.03 (1.00-1.06)] was also independently associated with ARDS development. In mechanically ventilated patients, driving pressure and plateau pressure are risk factors for mortality and ARDS, and provide similar information. Mechanical power is also a risk factor for ARDS.

  6. Studies of combustion kinetics and mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Gutman, D. [Catholic Univ. of America, Washington, DC (United States)

    1993-12-01

    The objective of the current research is to gain new quantitative knowledge of the kinetics and mechanisms of polyatomic free radicals which are important in hydrocarbon combustion processes. The special facility designed and built for these (which includes a heatable tubular reactor coupled to a photoionization mass spectrometer) is continually being improved. Where possible, these experimental studies are coupled with theoretical ones, sometimes conducted in collaboration with others, to obtain an improved understanding of the factors determining reactivity. The decomposition of acetyl radicals, isopropyl radicals, and n-propyl radicals have been studied as well as the oxidation of methylpropargyl radicals.

  7. TRANSPORT MECHANISM STUDIES OF CHITOSAN ELECTROLYTE SYSTEMS

    International Nuclear Information System (INIS)

    Navaratnam, S.; Ramesh, K.; Ramesh, S.; Sanusi, A.; Basirun, W.J.; Arof, A.K.

    2015-01-01

    ABSTRACT: Knowledge of ion-conduction mechanisms in polymers is important for designing better polymer electrolytes for electrochemical devices. In this work, chitosan-ethylene carbonate/propylene carbonate (chitosan-EC/PC) system with lithium acetate (LiCH 3 COO) and lithium triflate (LiCF 3 SO 3 ) as salts were prepared and characterized using electrochemical impedance spectroscopy to study the ion-conduction mechanism. It was found that the electrolyte system using LiCF 3 SO 3 salt had a higher ionic conductivity, greater dielectric constant and dielectric loss value compared to system using LiCH 3 COO at room temperature. Hence, it may be inferred that the system incorporated with LiCF 3 SO 3 dissociated more readily than LiCH 3 COO. Conductivity mechanism for the systems, 42 wt.% chitosan- 28 wt.% LiCF 3 SO 3 -30 wt.% EC/PC (CLT) and 42 wt.% chitosan-28 wt.% LiCH 3 COO-30 wt.% EC/PC (CLA) follows the overlapping large polaron tunneling (OLPT) model. Results show that the nature of anion size influences the ionic conduction of chitosan based polymer electrolytes. The conductivity values of the CLA system are found to be higher than that of CLT system at higher temperatures. This may be due to the vibration of bigger triflate anions would have hindered the lithium ion movements. FTIR results show that lithium ions can form complexation with polymer host which would provide a platform for ion hopping

  8. Exercise intolerance in pulmonary hypertension: mechanism, evaluation and clinical implications.

    Science.gov (United States)

    Babu, Abraham Samuel; Arena, Ross; Myers, Jonathan; Padmakumar, Ramachandran; Maiya, Arun G; Cahalin, Lawrence P; Waxman, Aaron B; Lavie, Carl J

    2016-09-01

    Exercise intolerance in pulmonary hypertension (PH) is a major factor affecting activities of daily living and quality of life. Evaluation strategies (i.e., non-invasive and invasive tests) are integral to providing a comprehensive assessment of clinical and functional status. Despite a growing body of literature on the clinical consequences of PH, there are limited studies discussing the contribution of various physiological systems to exercise intolerance in this patient population. This review, through a search of various databases, describes the physiological basis for exercise intolerance across the various PH etiologies, highlights the various exercise evaluation methods and discusses the rationale for exercise training amongst those diagnosed with PH. Expert commentary: With the growing importance of evaluating exercise capacity in PH (class 1, Level C recommendation), understanding why exercise performance is altered in PH is crucial. Thus, the further study is required for better quality evidence in this area.

  9. Quantum Mechanical Study of Atoms and Molecules

    Science.gov (United States)

    Sahni, R. C.

    1961-01-01

    This paper, following a brief introduction, is divided into five parts. Part I outlines the theory of the molecular orbital method for the ground, ionized and excited states of molecules. Part II gives a brief summary of the interaction integrals and their tabulation. Part III outlines an automatic program designed for the computation of various states of molecules. Part IV gives examples of the study of ground, ionized and excited states of CO, BH and N2 where the program of automatic computation and molecular integrals have been utilized. Part V enlists some special problems of Molecular Quantum Mechanics are being tackled at New York University.

  10. Recent studies on mechanisms in photoimmunology

    International Nuclear Information System (INIS)

    Krutmann, J.; Elmets, C.A.

    1988-01-01

    A review is given of the published material relevant to photoimmunology since 1984 with special emphasis on mechanistic studies. Topics covered include photoimmunology and contact hypersensitivity, UVB radiation and antigen presentation, mechanisms of suppressor cell induction by UVB, photosensitizer effects on contact hypersensitivity, expression of tumour antigens on UVB-induced tumours in mice, photoimmunology and organ transplantation, photoimmunology and the pathogenesis of lupus erythematosus, the effects of UV radiation on natural Riller cells and T lymphocytes, photoimmunological effects on mast cell function and finally technological advances in photoimmunology. (U.K.)

  11. Recent studies on mechanisms in photoimmunology

    Energy Technology Data Exchange (ETDEWEB)

    Krutmann, J; Elmets, C A

    1988-12-01

    A review is given of the published material relevant to photoimmunology since 1984 with special emphasis on mechanistic studies. Topics covered include photoimmunology and contact hypersensitivity, UVB radiation and antigen presentation, mechanisms of suppressor cell induction by UVB, photosensitizer effects on contact hypersensitivity, expression of tumour antigens on UVB-induced tumours in mice, photoimmunology and organ transplantation, photoimmunology and the pathogenesis of lupus erythematosus, the effects of UV radiation on natural Riller cells and T lymphocytes, photoimmunological effects on mast cell function and finally technological advances in photoimmunology. (U.K.).

  12. Evaluation and Development of Chemical Kinetic Mechanism Reduction Scheme for Biodiesel and Diesel Fuel Surrogates

    DEFF Research Database (Denmark)

    Poon, Hiew Mun; Ng, Hoon Kiat; Gan, Suyin

    2013-01-01

    The aim of this study is to evaluate the existing chemical kinetic mechanism reduction techniques. From here, an appropriate reduction scheme was developed to create compact yet comprehensive surrogate models for both diesel and biodiesel fuels for diesel engine applications. The reduction...... techniques applied here were Directed Relation Graph (DRG), DRG with Error Propagation, DRG-aided Sensitivity Analysis, and DRG with Error Propagation and Sensitivity Analysis. Nonetheless, the reduced mechanisms generated via these techniques were not sufficiently small for application in multi......-dimensional computational fluid dynamics (CFD) study. A new reduction scheme was therefore formulated. A 68-species mechanism for biodiesel surrogate and a 49-species mechanism for diesel surrogate were successfully derived from the respective detailed mechanisms. An overall 97% reduction in species number...

  13. Mechanical and Microstructural Evaluation of DMAG Welding of Structural Steel

    Directory of Open Access Journals (Sweden)

    Tolga Mert

    2015-01-01

    Full Text Available Double channel torch, which allows concentric flow of two different shielding gases, was designed and manufactured in order to pursue double channel torch gas metal arc welding of unalloyed structural steel S235JR (EN 10025-2 with fourteen passes. Tensile and Charpy V-notch tests were realized and the results were compared with those of conventional gas metal arc welding. In order to evaluate mechanical testing results, microstructural analyses were conducted. It was found that the increase with double channel gas metal arc welding process in yield and tensile strengths as well as in toughness tests, especially in subzero temperatures, compared with conventional gas metal arc welding was due to longer columnar grains and finer tempered zone grain structure between passes and due to solidification and less dendritic structure formation in all-weld metal in double channel gas metal arc welding.

  14. Fracture mechanics and fatigue evaluation of nuclear reactor components

    International Nuclear Information System (INIS)

    Mattar Neto, Miguel; Andrade, Arnaldo H.P. de; Maneschy, Eduardo

    1995-01-01

    This paper presents a theoretical study available in the available literature for evaluation the environmental effects on the lifetime of nuclear power plant components. The author's motivation is to provide some technical tools to identify what research development could be done in this area

  15. Effect of the Shrink Fit and Mechanical Tolerance on Reactor Coolant Pump Flywheel Integrity Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Donghak [Korea KHNP Central Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    Reactor coolant pump (RCP) flywheel should satisfy the RCP flywheel integrity criteria of the US NRC standard review plan (SRP) 5.4.1.1 and regulatory guide (RG) 1.14. Shrink-fit and rotational stresses should be calculated to evaluate the integrity. In this paper the effects of the shrink fit and mechanical tolerance on the RCP flywheel integrity evaluation are studied. The shrink fit should be determined by the joint release speed and the stresses in the flywheel will be increased by the shrink fit. The stress at the interface between the hub and the outer wheel shows the highest value. The effect of the mechanical tolerance should be considered for the stress evaluation. And the effect of the mechanical tolerance should be not considered to determine the joint release speed.

  16. Effect of the Shrink Fit and Mechanical Tolerance on Reactor Coolant Pump Flywheel Integrity Evaluation

    International Nuclear Information System (INIS)

    Kim, Donghak

    2015-01-01

    Reactor coolant pump (RCP) flywheel should satisfy the RCP flywheel integrity criteria of the US NRC standard review plan (SRP) 5.4.1.1 and regulatory guide (RG) 1.14. Shrink-fit and rotational stresses should be calculated to evaluate the integrity. In this paper the effects of the shrink fit and mechanical tolerance on the RCP flywheel integrity evaluation are studied. The shrink fit should be determined by the joint release speed and the stresses in the flywheel will be increased by the shrink fit. The stress at the interface between the hub and the outer wheel shows the highest value. The effect of the mechanical tolerance should be considered for the stress evaluation. And the effect of the mechanical tolerance should be not considered to determine the joint release speed

  17. Evaluation of the cryogenic mechanical properties of the insulation material for ITER Feeder superconducting joint

    Science.gov (United States)

    Wu, Zhixiong; Huang, Rongjin; Huang, ChuanJun; Yang, Yanfang; Huang, Xiongyi; Li, Laifeng

    2017-12-01

    The Glass-fiber reinforced plastic (GFRP) fabricated by the vacuum bag process was selected as the high voltage electrical insulation and mechanical support for the superconducting joints and the current leads for the ITER Feeder system. To evaluate the cryogenic mechanical properties of the GFRP, the mechanical properties such as the short beam strength (SBS), the tensile strength and the fatigue fracture strength after 30,000 cycles, were measured at 77K in this study. The results demonstrated that the GFRP met the design requirements of ITER.

  18. [Mechanical studies of lumbar interbody fusion implants].

    Science.gov (United States)

    Bader, R J; Steinhauser, E; Rechl, H; Mittelmeier, W; Bertagnoli, R; Gradinger, R

    2002-05-01

    In addition to autogenous or allogeneic bone grafts, fusion cages composed of metal or plastic are being used increasingly as spacers for interbody fusion of spinal segments. The goal of this study was the mechanical testing of carbon fiber reinforced plastic (CFRP) fusion cages used for anterior lumbar interbody fusion. With a special testing device according to American Society for Testing and Materials (ASTM) standards, the mechanical properties of the implants were determined under four different loading conditions. The implants (UNION cages, Medtronic Sofamor Danek) provide sufficient axial compression, shear, and torsional strength of the implant body. Ultimate axial compression load of the fins is less than the physiological compression loads at the lumbar spine. Therefore by means of an appropriate surgical technique parallel grooves have to be reamed into the endplates of the vertebral bodies according to the fin geometry. Thereby axial compression forces affect the implants body and the fins are protected from damaging loading. Using a supplementary anterior or posterior instrumentation, in vivo failure of the fins as a result of physiological shear and torsional spinal loads is unlikely. Due to specific complications related to autogenous or allogeneic bone grafts, fusion cages made of metal or carbon fiber reinforced plastic are an important alternative implant in interbody fusion.

  19. Study on pipe wastage mechanism by liquid droplet impingement erosion

    International Nuclear Information System (INIS)

    Higashi, Yuma; Narabayashi, Tadashi; Shimazu, Yoichiro; Tsuji, Masashi; Ohmori, Shuichi; Mori, Michitsugu; Tezuka, Kenichi

    2009-01-01

    Evaluation of wastage speed for nuclear power plant maintains plant reliability and power up rating is important. There are two main cause of wastage flow accelerated corrosion (FAC) and mechanical erosion. This study is to develop evaluating the wastage speed by liquid droplet impingement erosion (LDIE). LDIE often occurs at downstream of corner of pipe or orifice. In this study, the liquid drop impinging tests were conducted with the test pieces mounted on a high speed rotating disk that cross thin water down jet and produced LDIE phenomena. The amount of the wastage by LDIE was evaluated by changing the rotational speed, the impingement frequency, and test piece materials. In addition, the generation mechanism of erosion was investigated by observing the surface of the test piece with a microscope. There is a method of evaluating by the mass difference before and after experiments. But this method is not correct because error becomes larger for mass measurement in the experiment, for the lost mass by LDIE is very little amount. Therefore, the method was developed to measure the volume in the erosion part. In this method, depth of LDIE was measured by the accuracy of ±0.01μm; therefore accurate measurement of the wastage can be improved. (author)

  20. A comparative evaluation of mechanical properties of nanofibrous materials

    Science.gov (United States)

    Lyubun, German P.; Bessudnova, Nadezda O.

    2014-01-01

    Restoration or replacement of lost or damaged hard tooth tissues remain a reconstructive clinical dentistry challenge. One of the most promising solutions to this problem is the development of novel concepts and methodologies of tissue engineering for the synthesis of three-dimensional graft constructs that are equivalent to original organs and tissues. This structural and functional compatibility can be reached by producing ultra-thin polymer filament scaffolds. This research aims through a series of studies to examine different methods of polymer filament material special preparation and test mechanical properties of the produced materials subjected to a tensile strain. Nanofibrous material preparation using chemically pure acetone and mixtures of ethanol/water has shown no significant changes in sample surface morphology. The high temperature impact on material morphology has resulted in the modification of fiber structure. In the course of mechanical tests it has been revealed the dependence of the material strength on the spinning solution compositions. The results achieved point to the possibility to develop nanofibrous materials with required parameters changing the methodology of spinning solution production.

  1. Synthesis and evaluation of new organic and phosphorous derivatives against ionizing radiation: study of the in vitro mechanism of action; Synthese et evaluation de nouveaux composes organiques et phosphores contre les effets des rayonnements ionisants. Etude de leur mecanisme d'action in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Prouillac, C

    2006-10-15

    This work falls under a research program. The aim was to synthesize new organic phosphorylated compounds having an interesting radio pharmacological activity without toxicity. That is why, we carried out the synthesis of new benzothiazole and thiadiazole N-substituted derivatives as thiols, amino thiols, acids thio-sulfonic and phosphoro thioates. All these compounds were characterized by NMR (proton, carbon, phosphorus, 2D), by mass spectrometry, elementary analyzes and for some of them by diffraction of x-rays. The activity of the majority of them was evaluated by in vitro tests. The experimental results were confirmed by theoretical study: the aim of D.F.T. calculation was the study of the mechanism of capture of the free radicals by our compounds. In addition, a study of relation structure activity (Q.S.A.R.) was carried out. Our results allow us to create a model making it possible to establish structure-activity relationship. (author)

  2. Study of crotoxin mechanism of action to mammary carcinomas and evaluation of its potential as a radiopharmaceutical; Estudo do mecanismo de acao da crotoxina em tumores mamarios e avaliacao do seu potenctial radiofarmaceutico

    Energy Technology Data Exchange (ETDEWEB)

    Silveira, Marina Bicalho

    2010-07-01

    Crotoxin, the main component of Crotalus durissus terrificus snake venom, has been studied since 1938. It is a natural polypeptidic complex with pharmacological potential because of its antitumoral properties which has attracted great interest for diagnosis and therapy of oncological diseases. However, Crotoxin mechanism of action and sites of specific interaction on tumor cells are still misunderstood. Breast cancer is the second most frequent type in the world and the most common cancer in women. About 30 to 60% of mammary tumors overexpress epidermal growth factor receptor (EGFR), a transmembrane protein related to cell proliferation. Since literature has reported that Crotoxin antitumoral effect is more potent on cells with EGFR overexpression the objectives of this work were to evaluate Crotoxin cytotoxic effects on mammary tumor cells human breast carcinoma (MCF-7) and Ehrlich tumor cells (murine ascitics carcinoma), and to investigate the specific molecular interaction of Crotoxin on Ehrlich tumor cells. Initially, Crotoxin was radiolabelled with iodine-125 ({sup 125}I-Crotoxin) and iodine-131 ({sup 131}I-Crotoxin). Saturation and competition assay were carried out to characterize Crotoxin in vitro interaction; Crotoxin biodistribution studies and singlephoton emission computed tomography (SPECT) of mice bearing Ehrlich tumor have been evaluated to describe in vivo interaction. Our results showed that Crotoxin presented cytotoxic effect against Ehrlich with DL{sub 50} in vitro (concentration of compound which is lethal for 50% of cells) of about one micromolar, but did not present significant effect against MCF-7. Morphological alterations characteristic of apoptosis suggests programmed cell death. {sup 125}I-Crotoxin interaction with Ehrlich tumor cells was saturable with approximately 70% specificity, and presented K{sub d}=24.98 nmol/L and B{sub max}=16,570 sites/cell for low affinity binding sites and K{sub d}=0.06 nmol/L and B{sub max}=210 sites

  3. Mechanical properties of hyaline and repair cartilage studied by nanoindentation.

    Science.gov (United States)

    Franke, O; Durst, K; Maier, V; Göken, M; Birkholz, T; Schneider, H; Hennig, F; Gelse, K

    2007-11-01

    Articular cartilage is a highly organized tissue that is well adapted to the functional demands in joints but difficult to replicate via tissue engineering or regeneration. Its viscoelastic properties allow cartilage to adapt to both slow and rapid mechanical loading. Several cartilage repair strategies that aim to restore tissue and protect it from further degeneration have been introduced. The key to their success is the quality of the newly formed tissue. In this study, periosteal cells loaded on a scaffold were used to repair large partial-thickness cartilage defects in the knee joint of miniature pigs. The repair cartilage was analyzed 26 weeks after surgery and compared both morphologically and mechanically with healthy hyaline cartilage. Contact stiffness, reduced modulus and hardness as key mechanical properties were examined in vitro by nanoindentation in phosphate-buffered saline at room temperature. In addition, the influence of tissue fixation with paraformaldehyde on the biomechanical properties was investigated. Although the repair process resulted in the formation of a stable fibrocartilaginous tissue, its contact stiffness was lower than that of hyaline cartilage by a factor of 10. Fixation with paraformaldehyde significantly increased the stiffness of cartilaginous tissue by one order of magnitude, and therefore, should not be used when studying biomechanical properties of cartilage. Our study suggests a sensitive method for measuring the contact stiffness of articular cartilage and demonstrates the importance of mechanical analysis for proper evaluation of the success of cartilage repair strategies.

  4. Probabilistic fracture mechanics applied for lbb case study: international benchmark

    International Nuclear Information System (INIS)

    Radu, V.

    2015-01-01

    An application of probabilistic fracture mechanics to evaluate the structural integrity for a case study chosen from experimental Mock-ups of FP7 STYLE project is described. The reliability model for probabilistic structural integrity, focused on the assessment of TWC in the pipe weld under complex loading (bending moment and residual stress) has been setup. The basic model is the model of fracture for through-wall cracked pipe under elastic-plastic conditions. The corresponding structural reliability approach is developed with the probabilities of failure associated with maximum load for crack initiation, net-section collapse but also the evaluation the instability loads. The probabilities of failure for a through-wall crack in a pipe subject to pure bending are evaluated by using crude Monte Carlo simulations. The results from the international benchmark are presented for the mentioned case in the context of ageing and lifetime management of pressure boundary/pressure circuit component. (authors)

  5. An overview of studies in structural mechanics

    International Nuclear Information System (INIS)

    Guilbaud, D.; Blay, N.; Broc, D.; Chaudat, T.; Feau, C.; Sollogoub, P.; Wang, F.; Baj, F.; Bung, H.; Combescure, D.; Lepareux, M.; Phalippou, C.; Bentejac, F.; Hourdequin, N.; Laporte, T.; Millard, A.; Nicolas, L.; Chapuliot, S.; Fissolo, A.; Gourdin, C.; Kayser, Y.; Marie, S.; Reytier, M.; Yuritzinn, T.; Magnaud, J.P.; Braillard, O.; Collard, B.; Gobillot, G.; Mori, V.; Vallory, J.; Pascal-Ribot, S.; Pluyette, E.; Berton, M.N.; Cabrillat, M.T.; Lejeail, Y.

    2006-01-01

    -elastic instability velocity are being obtained. Moreover, influence of non-dimensional parameters that are characteristic of the coupled problem (Reynolds number, Stokes number, reduced velocity) and their influence on the evolution of modal parameters (added mass, damping and thickness) is being studied through parametric studies. The research actions described here, and those in progress are in agreement with the general pattern of the 'Mechanics 2010' program, but nevertheless the R and D effort is less extensive than it was expected. So, this activity would also deserve more effort in transverse fields like probabilistic methods, innovative measuring techniques and numerical methods. (authors)

  6. Evaluating mechanical properties of hybrid laser arc girth welds

    Energy Technology Data Exchange (ETDEWEB)

    Pussegoda, L. N.; Begg, D.; Holdstock, R.; Jodoin, A. [BMT Fleet Technology Ltd Techonology, Kanata, ON, (Canada); Ligh, K.; Rondeau, D. [Appliead Thermal Sciences Inc., Sanford, ME, (United States); Hansen, E. [ESAB, Florence, SC, (United States)

    2010-07-01

    Hybrid laser arc welding (HLAW) is a promising new process for making girth welds on steel pipelines. This study investigated the mechanical properties of overmatched X80 and X100 pipeline steel girth welds made using the HLAW process. The testing of this process was conducted on NPS36 pipes of 10.4 mm and 14.3 mm thickness, respectively. Various weld positions were produced on X80 and X100 pipes. Laser inspection data were collected during the whole welding process. Also standard tests for girth welds, Charpy V-notch impact tests, CTOD tests, all weld metal (AWM) tension tests, were carried out. The results showed that the fracture transition temperature is higher at the 3 and 9 o'clock positions than at the 9 and 12 o'clock positions. The effect of clock position on fracture toughness is currently being explored; a modified CTOD has been developed to reduce the possibility of crack deviation.

  7. Clinical evaluation of Carisolv in the chemico-mechanical removal of carious dentin.

    Science.gov (United States)

    Munshi, A K; Hegde, A M; Shetty, P K

    2001-01-01

    The Chemo-mechanical caries removal technique involves the application of chemical agents, to cause a selective softening of the carious dentine and facilitate removal by gentle excavation. Carisolv is one such new chemical agent used in this minimal invasive technique of carious dentine removal. The present study was, therefore, undertaken to evaluate the efficacy of Carisolv in the chemo-mechanical removal of carious dentine, the time taken for caries removal, the perception of the treatment by the patient, and to evaluate the restorations, radiographically. Accordingly, fifty primary and permanent molars with dentinal carious lesions were excavated using this technique of caries removal. The chemo-mechanical caries removal technique using Carisolv proved to be an effective atraumatic treatment modality with potential interest for use in clinical pediatric dentistry.

  8. Quantum mechanical studies of complex ferroelectric perovskites

    Science.gov (United States)

    Ramer, Nicholas John

    In many electronic device applications, there is a need to interconvert electrical energy and other types of energy. Ferroelectric materials, which possess a voltage-dependent polarization, can enable this energy conversion process. Because of the broad interest in ferroelectric materials for these devices, there is a critical research effort, both experimental and theoretical, to understand these materials and aid in the development of materials with improved properties. This thesis presents detailed quantum mechanical investigations of the behavior of a complex ferroelectric perovskite under applied stress. In particular, we have chosen to study the solid solution PbZr1-xTix O3 (PZT). Since the study of ferroelectricity involves understanding both its structural and electronic signatures in materials, it has necessitated the development of a novel theoretical technique which improves the accuracy of the pseudopotentials used in our density functional theory calculations as well as a new method for constructing three-dimensional atomistic responses to small amounts of external stress. To examine the material's behavior under larger amounts of stress, we have studied the behavior of a composition of PZT lying near a structural phase boundary. On either side of the phase boundary, the material is characterized by a different polarization direction and may easily be switched between phases by applying external stress. In addition to stress-induced phase transitions, most ferroelectric materials also have composition dependent phase boundaries. Since different compositions of PZT would require increased computational effort, we have formulated an improved virtual crystal approach that makes tractable the study of the entire composition range. Using this method, we have been able to show for the first time via first-principles calculations, a composition dependent phase transition in a ferroelectric material. This thesis has accomplished three important goals: new

  9. An Experimental Evaluation of Mechanical Properties of Hybrid Reinforcements

    Science.gov (United States)

    Sai Kumar, A.; Ganesan, G.; Karthikeyan, K.

    2017-07-01

    This paper presents the mechanical properties of unidirectional hybrid reinforcements formed from continuous fibres impregnated with a fibre binding material which are used for reinforcing the concrete. Recently FRP (Fibre Reinforced Polymer) manufacturers and suppliers have been increased all over the world because of the superior performance of FRP products in the construction industry. Its non-corrosive nature has turned the attention of many researchers to make several studies on different type of FRP products. Through a vast research, several standards also have been formulated. In this regard a new combination of FRP materials is tried in this paper and its properties have been derived. Carbon fibre and glass fibres fuse in this study to form a new hybrid rebar. The design properties such as tensile strength, tensile modulus, and compressive strength have been studied as per ASTM standards and it has been identified that the Hybrid rebar show a superior performance in comparison with GFRP (Glass FRP) and Steel rebars. This extraordinary performance of hybrid composite material increases the extensive engineering applications such as transport industry, aeronautics, naval, automotive industries.

  10. Evaluation of long-term mechanical stability of near field

    International Nuclear Information System (INIS)

    Takaji, Kazuhiko; Sugino, Hiroyuki; Okutsu, Kazuo; Miura, Kazuhiko; Tabei, Kazuto; Noda, Masaru; Takahashi, Shinichi; Sugie, Shigehiko

    1999-11-01

    In the near field, as tunnels and pits are excavated, a redistribution of stresses in the surrounding rock will occur. For a long period of time after the emplacement of waste packages various events will take place, such as the swelling of the buffer, sinking of the overpack under its own weight, deformation arising from expansion of overpack corrosion products and the creep deformation of the rock mass. The evaluation of what effects these changes in the stress-state will have on the buffer and rock mass is a major issue from the viewpoint of safety assessment. Therefore, rock creep analysis, overpack corrosion expansion analysis and overpack sinking analysis have been made in order to examine the long-term mechanical stability of the near field and the interaction of various events that may affect the stability of the near field over a long period of time. As the results, rock creep behavior, the variations of the stress-state and the range of the influence zone differ from the rock strength, strength of buffer in the tunnel and side pressure coefficient etc. about the hard rock system and soft rock system established as basic cases. And the magnitude of the stress variations for buffer by the overpack sinking and rock creep deformation is negligible compared with it by the overpack corrosion expansion. Furthermore, though very limited zone of buffer around the overpack is close to the critical state by the overpack corrosion expansion, the engineered barrier system attains a comparatively stable state for a long period of time. (author)

  11. Quantum Mechanics/Molecular Mechanics Study of the Sialyltransferase Reaction Mechanism.

    Science.gov (United States)

    Hamada, Yojiro; Kanematsu, Yusuke; Tachikawa, Masanori

    2016-10-11

    The sialyltransferase is an enzyme that transfers the sialic acid moiety from cytidine 5'-monophospho-N-acetyl-neuraminic acid (CMP-NeuAc) to the terminal position of glycans. To elucidate the catalytic mechanism of sialyltransferase, we explored the potential energy surface along the sialic acid transfer reaction coordinates by the hybrid quantum mechanics/molecular mechanics method on the basis of the crystal structure of sialyltransferase CstII. Our calculation demonstrated that CstII employed an S N 1-like reaction mechanism via the formation of a short-lived oxocarbenium ion intermediate. The computational barrier height was 19.5 kcal/mol, which reasonably corresponded with the experimental reaction rate. We also found that two tyrosine residues (Tyr156 and Tyr162) played a vital role in stabilizing the intermediate and the transition states by quantum mechanical interaction with CMP.

  12. Evaluation of glass transition temperature and dynamic mechanical properties of autopolymerized hard direct denture reline resins.

    Science.gov (United States)

    Takase, Kazuma; Watanabe, Ikuya; Kurogi, Tadafumi; Murata, Hiroshi

    2015-01-01

    This study assessed methods for evaluation of glass transition temperature (Tg) of autopolymerized hard direct denture reline resins using dynamic mechanical analysis and differential scanning calorimetry in addition to the dynamic mechanical properties. The Tg values of 3 different reline resins were determined using a dynamic viscoelastometer and differential scanning calorimeter, and rheological parameters were also determined. Although all materials exhibited higher storage modulus and loss modulus values, and a lower loss tangent at 37˚C with a higher frequency, the frequency dependence was not large. Tg values obtained by dynamic mechanical analysis were higher than those by differential scanning calorimetry and higher frequency led to higher Tg, while more stable Tg values were also obtained by that method. These results suggest that dynamic mechanical analysis is more advantageous for characterization of autopolymerized hard direct denture reline resins than differential scanning calorimetry.

  13. Study on Government Management Mechanism of Energy ...

    African Journals Online (AJOL)

    of energy conservation and emission reduction, and propose legal guarantees, management innovation, technology innovation, service system construction and upgrading of industrial structure are the critical factors to energy conservation and emission reduction management mechanism's performance. Then discuss the ...

  14. Study on modeling of operator's learning mechanism

    International Nuclear Information System (INIS)

    Yoshimura, Seichi; Hasegawa, Naoko

    1998-01-01

    One effective method to analyze the causes of human errors is to model the behavior of human and to simulate it. The Central Research Institute of Electric Power Industry (CRIEPI) has developed an operator team behavior simulation system called SYBORG (Simulation System for the Behavior of an Operating Group) to analyze the human errors and to establish the countermeasures for them. As an operator behavior model which composes SYBORG has no learning mechanism and the knowledge of a plant is fixed, it cannot take suitable actions when unknown situations occur nor learn anything from the experience. However, considering actual operators, learning is an essential human factor to enhance their abilities to diagnose plant anomalies. In this paper, Q learning with 1/f fluctuation was proposed as a learning mechanism of an operator and simulation using the mechanism was conducted. The results showed the effectiveness of the learning mechanism. (author)

  15. Market Competitiveness Evaluation of Mechanical Equipment with a Pairwise Comparisons Hierarchical Model.

    Science.gov (United States)

    Hou, Fujun

    2016-01-01

    This paper provides a description of how market competitiveness evaluations concerning mechanical equipment can be made in the context of multi-criteria decision environments. It is assumed that, when we are evaluating the market competitiveness, there are limited number of candidates with some required qualifications, and the alternatives will be pairwise compared on a ratio scale. The qualifications are depicted as criteria in hierarchical structure. A hierarchical decision model called PCbHDM was used in this study based on an analysis of its desirable traits. Illustration and comparison shows that the PCbHDM provides a convenient and effective tool for evaluating the market competitiveness of mechanical equipment. The researchers and practitioners might use findings of this paper in application of PCbHDM.

  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. Informing international UNFCCC technology mechanisms from the ground up: Using biogas technology in South Africa as a case study to evaluate the usefulness of potential elements of an international technology agreement in the UNFCCC negotiations process

    International Nuclear Information System (INIS)

    Boyd, Anya

    2012-01-01

    Transfer of low carbon technologies to developing countries is 1 approach for tackling rising global emissions. An international technology transfer mechanism has been proposed under the UNFCCC; however, it remains unclear how this international mechanism would translate into local level technology implementation. This study uses biogas technology in South Africa to obtain empirical data inductively related to technology transfer. Observations and activities specific to the biogas sector in South Africa are put forward based on site visits and stakeholder discussions in South Africa, the UK, Germany and Sweden. This paper presents empirical findings on technology transfer in the biogas sector in South Africa and analyses the role of an international technology mechanism in supporting the uptake of biogas. Many of the barriers to biogas technology in South Africa are national level constraints such as lack of supportive policy environment, financial incentives and information sharing. This case study supports the argument that it will be unrealistic for international technology mechanisms to capture the necessary specificities of individual technologies at a country level. Therefore, as demonstrated through the example of biogas technology in South Africa, there is a need for both effective national and international engagement to support technology implementation. - Highlights: ► The UNFCCC technology mechanism aims to increase low carbon technology deployment. ► The interface of global technology frameworks and national implementation is unclear. ► Biogas is a widely used technology yet its uptake in South Africa (SA) is minimal. ► Empirical data is gathered from biogas sites in SA, UK, Germany and Sweden. ► Findings show biogas uptake in SA requires national and international support

  18. Developing and Evaluating Animations for Teaching Quantum Mechanics Concepts

    Science.gov (United States)

    Kohnle, Antje; Douglass, Margaret; Edwards, Tom J.; Gillies, Alastair D.; Hooley, Christopher A.; Sinclair, Bruce D.

    2010-01-01

    In this paper, we describe animations and animated visualizations for introductory and intermediate-level quantum mechanics instruction developed at the University of St Andrews. The animations aim to help students build mental representations of quantum mechanics concepts. They focus on known areas of student difficulty and misconceptions by…

  19. The therapeutic evaluation and mechanism on treating bronchial ...

    African Journals Online (AJOL)

    ... the level of bronchial responsiveness, which proved a better curative effect of Chinese medicine. The mechanism is probably due to relieving the airway inflammation by keeping the balance between Th1 and Th2 cells. Keywords: Ziyinqingre prescription; cough; bronchial hyper-responsiveness; therapeutic mechanism ...

  20. High resolution studies of pion-nucleus reaction mechanism

    International Nuclear Information System (INIS)

    Morris, C.L.

    1983-01-01

    Pion inelastic scattering is generally well described as a first order process using the DWIA. This is especially true for a large body of inelastic scattering data to low-lying collective states which is well-described by form factors obtained in (e,e') and the DWIA. Some data for which this model does not work are presented. Higher order reaction mechanisms have been invoked to explain some of these data. However, no model of these second order processes gives a satisfactory explanation of the entire data set. Experimentally, more data for pion-induced transitions to low-spin unnatural-parity states which have been studied by other probes would be useful in sorting out the reaction mechanisms responsible for the anomalous cross sections observed for the 1 + states in 12 C. Theoretically, a consistent evaluation of possible second-order diagrams in inelastic scattering, such as is being attempted for DCX 22 , would be useful

  1. Characteristic Evaluation of a Shrouded Propeller Mechanism for a Magnetic Actuated Microrobot

    Directory of Open Access Journals (Sweden)

    Qiang Fu

    2015-09-01

    Full Text Available Medical microrobots have been widely used in clinical applications, particularly the spiral type locomotion mechanism, which was recently considered one of the main self-propelling mechanisms for the next medical microrobot to perform tasks such as capsule endoscopy and drug delivery. However, limits in clinical applications still exist. The spiral action of the microrobot while being used for diagnosis may lead to pain or even damage to the intestinal wall due to the exposed mechanisms. Therefore, a new locomotive mechanism, named the shrouded propeller mechanism, was proposed to achieve a high level of medical safety as well as effective propulsive performance in our study. The shrouded propeller mechanism consists of a bare spiral propeller and a non-rotating nozzle. To obtain a high effective propulsive performance, two types of screw grooves with different shapes including the cylindrical screw groove and the rectangular screw groove with different parameters were analyzed using the shrouded model. Two types of magnetic actuated microrobots with different driving modes, the electromagnetic (three-pole rotor actuated microrobot and the permanent magnet (O-ring type magnet actuated microrobot were designed to evaluate the performance of the electromagnetic actuation system. Based on experimental results, the propulsive force of the proposed magnetic actuated microrobot with a shrouded propeller was larger than the magnetic actuated microrobot with a bare spiral propeller under the same parameters. Additionally, the shrouded propeller mechanism as an actuator can be used for other medical microrobots for flexible locomotion.

  2. A Novel Method of Mechanical Oxidation of CNT for Polymer Nanocomposite Application: Evaluation of Mechanical, Dynamic Mechanical, and Rheological Properties

    Directory of Open Access Journals (Sweden)

    Priyanka Pandey

    2014-01-01

    Full Text Available A new approach of oxidation of carbon nanotubes has been used to oxidize the CNTs. A comparative aspect of the mechanical oxidation and acid oxidation process has been established. FTIR analysis and titration method have shown the higher feasibility of the mechanical oxidation method to oxidize the CNTs. Comparatively less damage to the CNTs has been observed in case of mechanically oxidized as compared to acid oxidized CNTs. The mechanical properties of the nanocomposites reinforced with the acid oxidized CNT (ACNT and mechanically oxidized CNTs (McCNT were analyzed and relatively higher properties in the nanocomposites reinforced with McCNT were noticed. The less degree of entanglement in the McCNTs was noticed as compared to ACNTs. The dynamic mechanical analysis of the nanocomposites revealed much improved load transfer capability in the McCNT reinforced composites. Further, the rheological properties of the nanocomposites revealed the higher performance of McCNT reinforced composites.

  3. Evaluation on mechanical and corrosion properties of steam generator tubing materials

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Sup; Lee, Byong Whi; Lee, Sang Kyu; Lee, Young Ho; Kim, Jun Whan; Lee, Ju Seok; Kwon, Hyuk Sang; Kim, Su Jung [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

    1998-06-15

    Steam generator is one of the major components of nuclear reactor pressure boundary. It's main function os transferring heat which generated in the reactor to turbine generator through steam generator tube. In these days, steam generator tubing materials of operating plant are used Inconel 600 alloys. But according to the operation time, there are many degradation phenomena which included mechanical damage due to flow induced vibration and corrosion damage due to PWSCC, IGA/SCC and pitting etc. Recently Inconel 690 alloys are selected as new and replacement steam generator tubes for domestic nuclear power plant. But there are few study about mechanical and corrosion properties of Inconel 600 and 690. The objectives of this study is to evaluate and compare mechanical and corrosion propertied of steam generator tube materials.

  4. Evaluation on mechanical and corrosion properties of steam generator tubing materials

    International Nuclear Information System (INIS)

    Kim, In Sup; Lee, Byong Whi; Lee, Sang Kyu; Lee, Young Ho; Kim, Jun Whan; Lee, Ju Seok; Kwon, Hyuk Sang; Kim, Su Jung

    1998-06-01

    Steam generator is one of the major components of nuclear reactor pressure boundary. It's main function os transferring heat which generated in the reactor to turbine generator through steam generator tube. In these days, steam generator tubing materials of operating plant are used Inconel 600 alloys. But according to the operation time, there are many degradation phenomena which included mechanical damage due to flow induced vibration and corrosion damage due to PWSCC, IGA/SCC and pitting etc. Recently Inconel 690 alloys are selected as new and replacement steam generator tubes for domestic nuclear power plant. But there are few study about mechanical and corrosion properties of Inconel 600 and 690. The objectives of this study is to evaluate and compare mechanical and corrosion propertied of steam generator tube materials

  5. Simulating Mechanics to Study Emergence in Games

    NARCIS (Netherlands)

    Dormans, Joris

    2011-01-01

    This paper presents the latest version of the Machinations framework. This framework uses diagrams to represent the flow of tangible and abstract resources through a game. This flow represents the mechanics that make up a game’s interbal economy and has a large impact on the emergent gameplay of

  6. Use of Isotopes for Studying Reaction Mechanisms

    Indian Academy of Sciences (India)

    of atoms during a chemical transformation. This strategy of determining reaction mechanisms is illustrated in the article with several examples. Introduction. When a reaction is carried out, the primary effort goes towards the identification of the product(s) of the reaction. A more time consuming endeavour, however, is the ...

  7. Evaluation of Hibiscus esculentus Linn. on the Mechanical and ...

    African Journals Online (AJOL)

    Malvaceae) on the mechanical and disintegration properties of paracetamol tablets were investigated against gum acacia as a standard binding agent. The effects of the nature and concentration of the mucilage binder and the relative density ...

  8. Evaluation of pesticide toxicities with differing mechanisms using Caenorhabditis elegans.

    Science.gov (United States)

    Ruan, Qin-Li; Ju, Jing-Juan; Li, Yun-Hui; Liu, Ran; Pu, Yue-Pu; Yin, Li-Hong; Wang, Da-Yong

    2009-01-01

    The aim of this study was to (1) determine whether model organism Caenorhabditis elegans was sensitive to pesticides at the maximum concentration limits regulated by national agency standards, and (2) examine the multi-biological toxicities occurring as a result of exposure to pesticides. Five pesticides, namely, chlorpyrifos, imibacloprid, buprofezin, cyhalothrin, and glyphosate, with four different mechanisms of action were selected for the investigation. In accordance with national agency requirements, 4 exposed groups were used for each tested pesticide with the concentration scales ranging from 1.0 x 10(-3) to 1 mg/L. L4 larvae were exposed for 24 and 72 h, respectively. Endpoints of locomotion, propagation, and development were selected for the assay as parameters of toxicity. After exposure for 24 h, both the body bend frequency and head thrash frequency of nematodes exposed to chlorpyrifos, imibacloprid, and cyhalothrin decreased in a concentration-dependent manner, and there were significant differences between exposed groups at maximum concentration level (MCL) compared to control. The generation time of nematodes exposed to buprofezin 24 h significantly increased in a concentration-dependent manner in the highest exposed group. When exposed for 72 h, the body bend frequency and head thrash frequency of nematodes exposed to cyhalothrin markedly decreased at MCL. The generation time and brood size of nematodes exposed to buprofezin were reduced in a concentration-dependent manner. The behavior of nematodes was sensitive to pesticides with neurotoxic properties, while pesticides affecting insect growth modified the reproductive system. The effects of pesticides on nematodes exposed for 24 h appeared more sensitive than with exposure for 72 h. Caenorhabditis elegans may thus be used for assessing the adverse effects of pesticide residues in aquatic environment.

  9. Mechanisms of masked evaluative priming: task sets modulate behavioral and electrophysiological priming for picture and words differentially

    OpenAIRE

    Kiefer, Markus; Liegel, Nathalie; Zovko, Monika; Wentura, Dirk

    2016-01-01

    Research with the evaluative priming paradigm has shown that affective evaluation processes reliably influence cognition and behavior, even when triggered outside awareness. However, the precise mechanisms underlying such subliminal evaluative priming effects, response activation vs semantic processing, are matter of a debate. In this study, we determined the relative contribution of semantic processing and response activation to masked evaluative priming with pictures and words. To this end,...

  10. Evaluation of Mechanical Properties of Nonsteroidal Anti-Inflammatory Matrix Type Transdermal Therapeutic Systems

    Directory of Open Access Journals (Sweden)

    Antonoaea Paula

    2017-06-01

    Full Text Available Objective: Transdermal therapeutic systems (TTSs represent an intensely studied alternative to oral delivery of non-steroid anti-inflammatory drugs (NSAIDs in the treatment of rheumatic diseases due to its ability of avoiding the side effects of the oral route. This study aims to present the evaluation of the mechanical properties of three NSAIDs (meloxicam, tenoxicam and indomethacin individually included in four type of polymeric matrixes, as part of new formulations development process. Methods: 12 products in form of TTS matrixes were prepared by solvent casting evaporation technique, using hydroxypropyl methylcellulose (HPMC 15000, HPMC E5 and/or ethylcellulose as matrix-forming polymers. Each of the resulted products was evaluated by determining the water vapor absorption, desorption or transmission in controlled atmosphere humidity (evaluation of porosity; the elongation capacity, tensile strength and bioadhesiveness (evaluation of mechanical properties. Results: The analysis of three groups of the experimental data expressed as averages on each group was necessary, in order to identify the parameters which statistically are critically influenced by the ingredients associated in the TTSs matrix compositions. Analysis by normality tests, variance and correlation tests (Anova, Pearson enabled evaluation of the effect of NSAID type vs. the effect of polymer matrix type on the parameters of the NSAID TTS matrix. Conclusions: Meloxicam incorporated in the structure of HPMC 15000 polymeric matrix favors its viscoelastic structure. Ethylcellulose functions as plasticizer and supports the matrix bioadhesiveness. HPMC E5 does not meet the requirements for TTS preparation in the used experimental conditions.

  11. Evaluation of the information quality in a company of metal-mechanical industry

    Directory of Open Access Journals (Sweden)

    Guilherme Augusto Spiegel Gualazzi

    2012-11-01

    Full Text Available This paper presents the application of an instrument for assessing the quality of information based on attributes such as accuracy, reliability, performance, among others. This instrument was applied in order to evaluate and identify ineffective information in a specific scenario of an engineering company in the metal-mechanic sector from the point of view of users of technical information. The case study aimed to demonstrate the applicability and functionality of the assessment instrument, the interest of people in evaluating their information and, finally, evaluate the scope of their results. The result of this evaluation allowed the company researched a plan of action to correct problems in its processes and identified inaccuracies in the information, indicating that the problem was solved by the method of problem solving.

  12. Undergraduate Teaching and Learning Evaluation: Focus on the Mechanism

    Science.gov (United States)

    Dongmei, Zeng; Jiangbo, Chen

    2009-01-01

    It is obvious to all that the National Undergraduate Teaching and Learning Evaluation plan for higher education institutions launched in 2003 has promoted undergraduate teaching at universities and colleges. At the same time, however, the authors have also witnessed problems with the evaluation work itself, for example, unified evaluation…

  13. Biological evaluation of mechanical circulatory support systems in calves

    NARCIS (Netherlands)

    Rakhorst, G; VanDerMeer, J; Kik, C; Mihaylov, D; Havlik, P; Trinkl, J; Monties, [No Value

    Data from animal experiments with mechanical circulatory support systems (MCSS) performed in Groningen and Marseille over the past years were used to obtain normal values of hematological, coagulation, rheological and blood chemistry parameters in calves. These parameters were divided between two

  14. Alternative evaluation of innovations’ effectiveness in mechanical engineering

    Science.gov (United States)

    Puryaev, A. S.

    2017-09-01

    The aim of present work is approbation of the developed technique for assessing innovations’ effectiveness. We demonstrate an alternative assessment of innovations’ effectiveness (innovation projects) in mechanical engineering on illustrative example. It is proposed as an alternative to the traditional method technique based on the value concept and the method of “Cash flow”.

  15. The Evaluation of Industry Practical of Mechanical Engineering in Vocational Education: A CIPP Model Approach

    Science.gov (United States)

    Kamaludin, M.; Munawar, W.; Mahdan, D.; Simanjuntak, M. V.; Wendi, H. F.

    2018-02-01

    The learning system is not only studied on campus but also practicing in the world of work. Industry Practical aims to enable students to develop their skills in accordance with the real world of work. To know the success of the implementation of industry practical program then held evaluation. The evaluation of the program in this study used the CIPP evaluation approach (Context, Input, Process, Product). The purpose of this research is to know the extent of achievement and success of industry practical program at vocational school in Bandung with descriptive research method using mix method approach. The sample in this research is students majoring in mechanical engineering in the city of Bandung who have done industry practical.

  16. Quantum Mechanical Study of Nanoscale MOSFET

    Science.gov (United States)

    Svizhenko, Alexei; Anantram, M. P.; Govindan, T. R.; Biegel, Bryan

    2001-01-01

    The steady state characteristics of MOSFETS that are of practical Interest are the drive current, off-current, dope of drain current versus drain voltage, and threshold voltage. In this section, we show that quantum mechanical simulations yield significantly different results from drift-diffusion based methods. These differences arise because of the following quantum mechanical features: (I) polysilicon gate depletion in a manner opposite to the classical case (II) dependence of the resonant levels in the channel on the gate voltage, (III) tunneling of charge across the gate oxide and from source to drain, (IV) quasi-ballistic flow of electrons. Conclusions dI/dV versus V does not increase in a manner commensurate with the increase in number of subbands. - The increase in dI/dV with bias is much smaller then the increase in the number of subbands - a consequence of bragg reflection. Our calculations show an increase in transmission with length of contact, as seen in experiments. It is desirable for molecular electronics applications to have a small contact area, yet large coupling. In this case, the circumferential dependence of the nanotube wave function dictates: - Transmission in armchair tubes saturates around unity - Transmission in zigzag tubes saturates at two.

  17. Evaluation of ionizing radiation effects in bone tissue by FTIR spectroscopy and dynamic mechanical analysis

    International Nuclear Information System (INIS)

    Veloso, Marcelo N.; Santin, Stefany P.; Benetti, Carolina; Pereira, Thiago M.; Mattor, Monica B.; Politano, Rodolfo; Zezell, Denise M.

    2013-01-01

    In many medical practices the bone tissue exposure to ionizing radiation is necessary. However, this radiation can interact with bone tissue in a molecular level, causing chemical and mechanical changes related with the dose used. The aim of this study was verify the changes promoted by different doses of ionizing radiation in bone tissue using spectroscopy technique of Attenuate Total Reflectance - Fourier Transforms Infrared (ATR-FTIR) and dynamic mechanical analysis. Samples of bovine bone were irradiated using irradiator of Cobalt-60 with five different doses between 0.01 kGy, 0.1 kGy,1 kGy, 15 kGy and 75 kGy. To study the effects of ionizing irradiation on bone chemical structure the sub-bands of amide I and the crystallinity index were studied. The mechanical changes were evaluated using the elastic modulus and the damping value. To verify if the chemical changes and the bone mechanic characteristics were related, it was made one study about the correlation between the crystallinity index and the elastic modulus, between the sub-bands ratio and the damping value and between the sub-bands ratio and the elastic modulus. It was possible to evaluate the effects of different dose of ionizing radiation in bone tissue. With ATR-FTIR spectroscopy analysis, it was possible observe changes in the organic components and in the hydroxyapatite crystals organization. Changes were also observed in the mechanical properties. A good correlation between the techniques was found, however, it was not possible to establish a linear or exponential dependence between dose and effect. (author)

  18. Parametric study of control mechanism of cortical bone remodeling under mechanical stimulus

    Science.gov (United States)

    Wang, Yanan; Qin, Qing-Hua

    2010-03-01

    The control mechanism of mechanical bone remodeling at cellular level was investigated by means of an extensive parametric study on a theoretical model described in this paper. From a perspective of control mechanism, it was found that there are several control mechanisms working simultaneously in bone remodeling which is a complex process. Typically, an extensive parametric study was carried out for investigating model parameter space related to cell differentiation and apoptosis which can describe the fundamental cell lineage behaviors. After analyzing all the combinations of 728 permutations in six model parameters, we have identified a small number of parameter combinations that can lead to physiologically realistic responses which are similar to theoretically idealized physiological responses. The results presented in the work enhanced our understanding on mechanical bone remodeling and the identified control mechanisms can help researchers to develop combined pharmacological-mechanical therapies to treat bone loss diseases such as osteoporosis.

  19. EGFR-targeted anti-cancer drugs in radiotherapy: Preclinical evaluation of mechanisms

    International Nuclear Information System (INIS)

    Baumann, Michael; Krause, Mechthild; Dikomey, Ekkehard; Dittmann, Klaus; Doerr, Wolfgang; Kasten-Pisula, Ulla; Rodemann, H. Peter

    2007-01-01

    Preclinical and clinical results indicate that the EGFR can mediate radioresistance in different solid human tumours. Combination of radiotherapy and EGFR inhibitors can improve local tumour control compared to irradiation alone and has been introduced into clinical radiotherapy practice. So far several mechanisms have been identified in preclinical studies to contribute to improved local tumour control after radiation combined with EGFR inhibitors. These include direct kill of cancer stem cells by EGFR inhibitors, cellular radiosensitization through modified signal transduction, inhibition of repair of DNA damage, reduced repopulation and improved reoxygenation during fractionated radiotherapy. Effects and mechanisms may differ for different classes of EGFR inhibitors, for different tumours and for normal tissues. The mechanisms underlying this heterogeneity are currently poorly understood, and predictive assays are not available yet. Importantly, mechanisms and predictors for the combined effects of radiation with EGFR inhibitors appear to be considerably different to those for application of EGFR inhibitors alone or in combination with chemotherapy. Therefore to further evaluate the efficacy and mechanisms of EGFR-inhibition in combined treatments, radiotherapy-specific preclinical research strategies, which include in vivo experiments using local tumour control as an endpoint, as well as animal studies on normal tissue toxicity are needed

  20. Mechanical and Thermal Properties of Praseodymium Monopnictides: AN Ultrasonic Study

    Science.gov (United States)

    Bhalla, Vyoma; Kumar, Raj; Tripathy, Chinmayee; Singh, Devraj

    2013-09-01

    We have computed ultrasonic attenuation, acoustic coupling constants and ultrasonic velocities of praseodymium monopnictides PrX(X: N, P, As, Sb and Bi) along the , , in the temperature range 100-500 K using higher order elastic constants. The higher order elastic constants are evaluated using Coulomb and Born-Mayer potential with two basic parameters viz. nearest-neighbor distance and hardness parameter in the temperature range of 0-500 K. Several other mechanical and thermal parameters like bulk modulus, shear modulus, Young's modulus, Poisson ratio, anisotropic ratio, tetragonal moduli, Breazeale's nonlinearity parameter and Debye temperature are also calculated. In the present study, the fracture/toughness (B/G) ratio is less than 1.75 which implies that PrX compounds are brittle in nature at room temperature. The chosen material fulfilled Born criterion of mechanical stability. We also found the deviation of Cauchy's relation at higher temperatures. PrN is most stable material as it has highest valued higher order elastic constants as well as the ultrasonic velocity. Further, the lattice thermal conductivity using modified approach of Slack and Berman is determined at room temperature. The ultrasonic attenuation due to phonon-phonon interaction and thermoelastic relaxation mechanisms have been computed using modified Mason's approach. The results with other well-known physical properties are useful for industrial applications.

  1. Dimensionless study on dynamics of pressure controlled mechanical ventilation system

    International Nuclear Information System (INIS)

    Shi, Yan; Niu, Jinglong; Cai, Maolin; Xu, Weiqing

    2015-01-01

    Dynamics of mechanical ventilation system can be referred in pulmonary diagnostics and treatments. In this paper, to conveniently grasp the essential characteristics of mechanical ventilation system, a dimensionless model of mechanical ventilation system is presented. For the validation of the mathematical model, a prototype mechanical ventilation system of a lung simulator is proposed. Through the simulation and experimental studies on the dimensionless dynamics of the mechanical ventilation system, firstly, the mathematical model is proved to be authentic and reliable. Secondly, the dimensionless dynamics of the mechanical ventilation system are obtained. Last, the influences of key parameters on the dimensionless dynamics of the mechanical ventilation system are illustrated. The study provides a novel method to study the dynamic of mechanical ventilation system, which can be referred in the respiratory diagnostics and treatment.

  2. Dimensionless study on dynamics of pressure controlled mechanical ventilation system

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Yan; Niu, Jinglong; Cai, Maolin; Xu, Weiqing [Beihang University, Beijing (Korea, Republic of)

    2015-02-15

    Dynamics of mechanical ventilation system can be referred in pulmonary diagnostics and treatments. In this paper, to conveniently grasp the essential characteristics of mechanical ventilation system, a dimensionless model of mechanical ventilation system is presented. For the validation of the mathematical model, a prototype mechanical ventilation system of a lung simulator is proposed. Through the simulation and experimental studies on the dimensionless dynamics of the mechanical ventilation system, firstly, the mathematical model is proved to be authentic and reliable. Secondly, the dimensionless dynamics of the mechanical ventilation system are obtained. Last, the influences of key parameters on the dimensionless dynamics of the mechanical ventilation system are illustrated. The study provides a novel method to study the dynamic of mechanical ventilation system, which can be referred in the respiratory diagnostics and treatment.

  3. Lattice mechanics of ionic crystals - unified study

    International Nuclear Information System (INIS)

    Sengupta, S.; Roy, D.; Basu, A.N.

    1979-01-01

    The up-to-date situation in the understanding of the mechanical properties of ionic solids is reviewed. These properties are determined by the Born-Oppenheimer (B-O) potential energy function. For ionic crystals this potential energy function can be written down with some precision. To keep the expression tractable, the dominant electron deformation, the dipolar deformation, is treated as an adiabatic variable and the energy then becomes a function of both the nuclear coordinates and the ionic dipole moments. All the well known models for ionic crystals are discussed in terms of the energy expression they imply. This makes the comparison straight forward and brings out the essential difference between the models clearly. Next various quantum mechanical treatments for ionic crystals are reviewed. An attempt is made to obtain the B-O potential energy expression using a Heitler-London approach. By comparing the various models one can arrive at some definitive conclusions about the degree of validity and the assumptions underlying these models. Finally a comprehensive review of the results of actual computation on various ionic crystals done by different authors is undertaken. The crucial quantitative results are examined and the success and shortcoming of each calculation are critically analysed. The guiding principle in this part is the unified approach. i.e. to see how far a model with a given set of parameters accounts for both the dynamic and static properties. The discussion is divided in three sections for crystals with sodium chloride, cesium chloride and zinc sulfide structures. Outstanding problems and difficulties in the present understanding are pointed out. (auth.)

  4. Developing and evaluating animations for teaching quantum mechanics concepts

    International Nuclear Information System (INIS)

    Kohnle, Antje; Douglass, Margaret; Edwards, Tom J; Gillies, Alastair D; Hooley, Christopher A; Sinclair, Bruce D

    2010-01-01

    In this paper, we describe animations and animated visualizations for introductory and intermediate-level quantum mechanics instruction developed at the University of St Andrews. The animations aim to help students build mental representations of quantum mechanics concepts. They focus on known areas of student difficulty and misconceptions by including animated step-by-step explanations of key points. The animations are freely available, with additional resources available to instructors. We have investigated their educational effectiveness both in terms of student attitude and performance. Questionnaires showed that students are on the whole very positive about the animations and make substantial use of them. A diagnostic survey administered to level 2 and 3 students showed that level 2 students significantly outperformed level 3 students on topics which they had investigated using the animations.

  5. Mechanical And Microstructural Evaluation Of A Wear Resistant Steel

    International Nuclear Information System (INIS)

    Santos, F.L.F. dos; Vieira, A.G.; Correa, E.C.S.; Pinheiro, I.P.

    2010-01-01

    In the present work, the analysis of the mechanical properties and the microstructural features of a high strength low alloy steel, containing chromium, molybdenum and boron, subjected to different heat treatments, was conducted. After austenitizing at 910 deg C for 10 minutes, three operations were carried out: oil quenching, oil quenching followed by tempering at 200 deg C for 120 minutes and austempering at 400 deg C for 5 minutes followed by water cooling. The analysis was performed through tensile and hardness tests, optical microscopy and X-ray diffraction. The bainitic structure led to high strength and toughness, both essential mechanical properties for wear resistant steels. The occurrence of allotriomorphic ferrite and retained austenite in the samples also increased the wear resistance. This phenomenon is related to the fact that both structures are able to be deformed and, in the case of the retained austenite, the transformation induced plasticity TRIP effect may take place as the material is used. (author)

  6. Experimental evaluation of mechanical properties of softwood using acoustic methods

    Czech Academy of Sciences Publication Activity Database

    Tippner, J.; Hrivnák, J.; Kloiber, Michal

    2016-01-01

    Roč. 11, č. 1 (2016), s. 503-518 ISSN 1930-2126 R&D Projects: GA MK(CZ) DF11P01OVV001 Keywords : non destructive testing * Norway spruce * Scots pine * Silver fir * sound speed * strength * stress wave Subject RIV: AL - Art, Architecture, Cultural Heritage Impact factor: 1.321, year: 2016 http://ojs.cnr.ncsu.edu/index.php/BioRes/article/view/BioRes_11_1_503_Tippner_Mechanical_Properties_Acoustic_Methods/4018

  7. Evaluation of Biaxial Mechanical Properties of Aortic Media Based on the Lamellar Microstructure

    Directory of Open Access Journals (Sweden)

    Hadi Taghizadeh

    2015-01-01

    Full Text Available Evaluation of the mechanical properties of arterial wall components is necessary for establishing a precise mechanical model applicable in various physiological and pathological conditions, such as remodeling. In this contribution, a new approach for the evaluation of the mechanical properties of aortic media accounting for the lamellar structure is proposed. We assumed aortic media to be composed of two sets of concentric layers, namely sheets of elastin (Layer I and interstitial layers composed of mostly collagen bundles, fine elastic fibers and smooth muscle cells (Layer II. Biaxial mechanical tests were carried out on human thoracic aortic samples, and histological staining was performed to distinguish wall lamellae for determining the dimensions of the layers. A neo-Hookean strain energy function (SEF for Layer I and a four-parameter exponential SEF for Layer II were allocated. Nonlinear regression was used to find the material parameters of the proposed microstructural model based on experimental data. The non-linear behavior of media layers confirmed the higher contribution of elastic tissue in lower strains and the gradual engagement of collagen fibers. The resulting model determines the nonlinear anisotropic behavior of aortic media through the lamellar microstructure and can be assistive in the study of wall remodeling due to alterations in lamellar structure during pathological conditions and aging.

  8. Summary of case studies for cooperation mechanisms

    DEFF Research Database (Denmark)

    Longa, Francesco Dalla; Klinge Jacobsen, Henrik; Hansen, Lise-Lotte Pade

    2012-01-01

    This document is a summary report highlighting the main aspect analyzed in the RES4LESS case studies. The document starts with an introductory chapter where the background that led to the selection of the case studies is outlined. In the following three chapters the case studies are presented, hi...

  9. Evaluation of restoration mechanisms for future services using Carrier Ethernet

    DEFF Research Database (Denmark)

    Wessing, Henrik; Berger, Michael Stübert; Gestsson, H.M.

    2010-01-01

    In this paper, we evaluate and classify future service according to their requirements for delay, loss and bandwidth. The most demanding services include IPTV in different forms, hence IPTV is used as a representative for future services. Carrier Ethernet technologies are introduced with special...... focus on its OAM functionalities, and it is evaluated how IPTV performs in case of link failures on a Carrier Ethernet implementation. It is concluded that OAM update times of 10 ms is required to provide acceptable restoration performance in case of errors....

  10. Biological and mechanical evaluation of a Bio-Hybrid scaffold for autologous valve tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Jahnavi, S [Stem Cell and Molecular Biology Laboratory, Department of Biotechnology, Indian Institute of Technology Madras, Chennai, TN 600036 (India); Tissue Culture Laboratory, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Poojappura, Trivandrum, Kerala 695012 (India); Saravanan, U [Department of Civil Engineering, Indian Institute of Technology Madras, Chennai, TN 600036 (India); Arthi, N [Stem Cell and Molecular Biology Laboratory, Department of Biotechnology, Indian Institute of Technology Madras, Chennai, TN 600036 (India); Bhuvaneshwar, G S [Department of Engineering Design, Indian Institute of Technology Madras, Chennai, TN 600036 (India); Kumary, T V [Tissue Culture Laboratory, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Poojappura, Trivandrum, Kerala 695012 (India); Rajan, S [Madras Medical Mission, Institute of Cardio-Vascular Diseases, Mogappair, Chennai, Tamil Nadu 600037 (India); Verma, R S, E-mail: vermars@iitm.ac.in [Stem Cell and Molecular Biology Laboratory, Department of Biotechnology, Indian Institute of Technology Madras, Chennai, TN 600036 (India)

    2017-04-01

    Major challenge in heart valve tissue engineering for paediatric patients is the development of an autologous valve with regenerative capacity. Hybrid tissue engineering approach is recently gaining popularity to design scaffolds with desired biological and mechanical properties that can remodel post implantation. In this study, we fabricated aligned nanofibrous Bio-Hybrid scaffold made of decellularized bovine pericardium: polycaprolactone-chitosan with optimized polymer thickness to yield the desired biological and mechanical properties. CD44{sup +}, αSMA{sup +}, Vimentin{sup +} and CD105{sup −} human valve interstitial cells were isolated and seeded on these Bio-Hybrid scaffolds. Subsequent biological evaluation revealed interstitial cell proliferation with dense extra cellular matrix deposition that indicated the viability for growth and proliferation of seeded cells on the scaffolds. Uniaxial mechanical tests along axial direction showed that the Bio-Hybrid scaffolds has at least 20 times the strength of the native valves and its stiffness is nearly 3 times more than that of native valves. Biaxial and uniaxial mechanical studies on valve interstitial cells cultured Bio-Hybrid scaffolds revealed that the response along the axial and circumferential direction was different, similar to native valves. Overall, our findings suggest that Bio-Hybrid scaffold is a promising material for future development of regenerative heart valve constructs in children. - Highlights: • We report detailed biological and mechanical investigations of a Bio-Hybrid scaffold. • Optimized polymer thickness yielded desired biological and mechanical properties. • Bio-Hybrid scaffold revealed hVIC proliferation with dense ECM deposition. • Biaxial testing indicated that Bio-Hybrid scaffolds are mechanically stronger than native valves. • Bio-Hybrid scaffold is a promising material for autologous valve tissue engineering.

  11. Evaluation of the sheet mechanical response to laser welding processes

    International Nuclear Information System (INIS)

    Carmignani, B.; Daneri, A.; Toselli, G.; Bellei, M.

    1995-07-01

    The simulation of the mechanical response of steel sheets, due to the heating during welding processes by a laser source beam, obtained by Abaqus standard code, is discussed. Different hypotheses for the material behaviour at temperatures greater than the fusion one have been tested and compared; in particular, some tests have been made taking the annealing effect into account by means of an user routine UMAT developed ad hoc. This work was presented at the 8th international Abaqus Users' conference at Paris, 31 May - 2 June 1995

  12. Evaluation of lung and chest wall mechanics during anaesthesia using the PEEP-step method.

    Science.gov (United States)

    Persson, P; Stenqvist, O; Lundin, S

    2018-04-01

    Postoperative pulmonary complications are common. Between patients there are differences in lung and chest wall mechanics. Individualised mechanical ventilation based on measurement of transpulmonary pressures would be a step forward. A previously described method evaluates lung and chest wall mechanics from a change of ΔPEEP and calculation of change in end-expiratory lung volume (ΔEELV). The aim of the present study was to validate this PEEP-step method (PSM) during general anaesthesia by comparing it with the conventional method using oesophageal pressure (PES) measurements. In 24 lung healthy subjects (BMI 18.5-32), three different sizes of PEEP steps were performed during general anaesthesia and ΔEELVs were calculated. Transpulmonary driving pressure (ΔPL) for a tidal volume equal to each ΔEELV was measured using PES measurements and compared to ΔPEEP with limits of agreement and intraclass correlation coefficients (ICC). ΔPL calculated with both methods was compared with a Bland-Altman plot. Mean differences between ΔPEEP and ΔPL were mechanical properties among the lung healthy patients stresses the need for individualised ventilator settings based on measurements of lung and chest wall mechanics. The agreement between ΔPLs measured by the two methods during general anaesthesia suggests the use of the non-invasive PSM in this patient population. NCT 02830516. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  13. Strategies for Evaluating a Freshman Studies Program.

    Science.gov (United States)

    Ketkar, Kusum; Bennett, Shelby D.

    1989-01-01

    The study developed an economic model for the evaluation of Seaton Hall University's freshman studies program. Two techniques used to evaluate the economic success of the program are break-even analysis and elasticity coefficient. (Author/MLW)

  14. Study of mechanisms and kinetics of Sodium-CO2 interactions. Contribution to the evaluation of an energy conversion system with supercritical CO2 for sodium fast breeder reactors

    International Nuclear Information System (INIS)

    Gicquel, L.

    2010-01-01

    This PhD study consisted in studying reactive mechanisms and kinetics of sodium-CO 2 interactions, in the frame of the assessment of an energy conversion system with supercritical CO 2 for fast breeder reactors cooled by sodium. The approach was the following. First of all, the interactions between sodium and CO 2 have been brought to light by laboratory experiments associated with products analysis. They have enabled the establishment of a coherent mechanism, in agreement with literature data, and gave preliminary indications on the reaction kinetics. In order to estimate a more detailed reaction kinetics, we tried to approach the phenomenon that appears in the case of a leak in a sodium-CO 2 heat exchanger. Geometry of such heat exchangers is not fixed for the moment, even if the development of compact exchangers is foreseen. Then, free jets of CO 2 in liquid sodium have been modeled in order to obtain, by identification, kinetics parameters of the reaction. Those parameters, estimated with such a geometry, will remain valid with a much complex geometry, that will better represent the real exchanger. An experimental bench has been defined and built to realize those jets. The first laboratory experiments have concluded in the existence of different reactive mechanisms according to the temperature level. A threshold has been brought to light around 500 C. Below this one, reaction appears moderated, or even, slow, with a medium exothermicity, and appears after an induction period that depends on the temperature,and which duration could reach several hours. At contrary, above this threshold, it seems rapid and more exothermic. Below 500 C, sodium oxalate is produced, and then reacts with sodium in an exothermic way, following the reactions: CO 2 + Na →1/4 Na 2 C 2 O 4 + 1/4 CO + 1/4 Na 2 CO 3 (5) 4 Na + Na 2 C 2 O 4 → 3 Na 2 O + CO + C (6) Above 500 C, sodium carbonate is produced, and can then possibly react with sodium in an endothermic way, following the

  15. Thermal assault and polyurethane foam-evaluating protective mechanisms

    International Nuclear Information System (INIS)

    Williamson, C.L.; Iams, Z.L.

    2004-01-01

    Rigid polyurethane foam utilizes a variety of mechanisms to mitigate the thermal assault of a ''regulatory burn''. Polymer specific heat and foam k-factor are of limited usefulness in predicting payload protection. Properly formulated rigid polyurethane foam provides additional safeguards by employing ablative mechanisms which are effective even when the foam has been crushed or fractured as a result of trauma. The dissociative transitions from polymer to gas and char, and the gas transport of heat from inside the package out into the environment are also thermal mitigators. Additionally, the in-situ production of an intumescent, insulative, carbonaceous char, confers thermal protection even when a package's outer steel skin has been breached. In this test program, 19 liter, ''Five gallon'' steel pails are exposed on one end to the flame of an ''Oil Burner'' as described in the US Federal Aviation Administration (FAA) ''Aircraft Materials Fire Test Handbook''. When burning 2 diesel at a nominal rate of 8.39 kg (18.5 pounds)/hr, the burner generates a high emissivity flame that impinges on the pail face with the thermal intensity of a full scale pool-fire environment. Results of these tests, TGA and MDSC analysis on the subject foams are reported, and their relevance to full size packages and pool fires are discussed

  16. Mechanical and Physicochemical Evaluation of Alkaleri Fireclay for Refractory Application

    Directory of Open Access Journals (Sweden)

    Job Ajala Amkpa

    2017-04-01

    Full Text Available The mechanical, chemical and physical property of Alkaleri fireclay was investigated for its appropriateness for refractory application. The chemical composition was performed and analyzed using the X-ray fluorescence (XRF spectrometer Bench top XRF analyzer technique. Chemical property result indicated that the clay contained 67.4 % silica (SiO2, 30.06 % aluminum (Al2O3, and other impurities. The clay was subjected to mechanical activation through sintering process at varied sintering temperatures of 900 °C, 1000 °C, 1100 °C and 1200 °C. At the best sintering temperature of 1200 °C, the cold crushing strength (CCS was 17.82 MPa, in the physical properties; apparent porosity was 22.8 %, bulk density was 1.8 g/cm3, and firing shrinkage was 8.9 %. The Alkaleri clay belongs to alumino-silicate fireclay group and therefore, suitable materials for refractory application of ladle, kiln dryer, boilers, cook stoves, furnace lining and bricks.

  17. Bioactive glass/hydroxyapatite composites: mechanical properties and biological evaluation.

    Science.gov (United States)

    Bellucci, Devis; Sola, Antonella; Anesi, Alexandre; Salvatori, Roberta; Chiarini, Luigi; Cannillo, Valeria

    2015-06-01

    Bioactive glass/hydroxyapatite composites for bone tissue repair and regeneration have been produced and discussed. The use of a recently developed glass, namely BG_Ca/Mix, with its low tendency to crystallize, allowed one to sinter the samples at a relatively low temperature thus avoiding several adverse effects usually reported in the literature, such as extensive crystallization of the glassy phase, hydroxyapatite (HA) decomposition and reaction between HA and glass. The mechanical properties of the composites with 80wt.% BG_Ca/Mix and 20wt.% HA are sensibly higher than those of Bioglass® 45S5 reference samples due to the presence of HA (mechanically stronger than the 45S5 glass) and to the thermal behaviour of the BG_Ca/Mix, which is able to favour the sintering process of the composites. Biocompatibility tests, performed with murine fibroblasts BALB/3T3 and osteocites MLO-Y4 throughout a multi-parametrical approach, allow one to look with optimism to the produced composites, since both the samples themselves and their extracts do not induce negative effects in cell viability and do not cause inhibition in cell growth. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Evaluation of the basic mechanical and thermal properties of deep crystalline rocks

    International Nuclear Information System (INIS)

    Park, Byoung Yoon; Bae, Dae Seok; Kim, Chun Soo; Kim, Kyung Su; Koh, Young Kwon; Jeon, Seok Won

    2001-04-01

    This report provides the mechanical and thermal properties of granitic intact rocks obtained from Deep Core Drilling Program which is carried out as part of the assessment of deep geological environmental condition. These data are the basic material properties of the core samples from the boreholes drilled up to 500 m depth at the Yusung and Kosung sites. These sites were selected based on the result of preliminary site evaluation study. In this study, the mechanical properties include density, porosity, P-wave velocity, S-wave velocity, uniaxial compressive strength, Young's modulus, Poisson's ratio, tensile strength, and shear strength of fractures, and the thermal properties are heat conductivity, thermal expansion coefficient, specific heat and so on. Those properties were measured through laboratory tests and these data are compared with the existing test results of several domestic rocks

  19. Evaluation of the basic mechanical and thermal properties of deep crystalline rocks

    Energy Technology Data Exchange (ETDEWEB)

    Park, Byoung Yoon; Bae, Dae Seok; Kim, Chun Soo; Kim, Kyung Su; Koh, Young Kwon; Jeon, Seok Won

    2001-04-01

    This report provides the mechanical and thermal properties of granitic intact rocks obtained from Deep Core Drilling Program which is carried out as part of the assessment of deep geological environmental condition. These data are the basic material properties of the core samples from the boreholes drilled up to 500 m depth at the Yusung and Kosung sites. These sites were selected based on the result of preliminary site evaluation study. In this study, the mechanical properties include density, porosity, P-wave velocity, S-wave velocity, uniaxial compressive strength, Young's modulus, Poisson's ratio, tensile strength, and shear strength of fractures, and the thermal properties are heat conductivity, thermal expansion coefficient, specific heat and so on. Those properties were measured through laboratory tests and these data are compared with the existing test results of several domestic rocks.

  20. Technical activities report: Mechanical development studies

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, W.K.

    1952-05-01

    This monthly progress report covers activities in the following areas: pile control; shielding studies; process tube assembly; pile operating equipment; power recovery; pile piping; and test laboratory. A detailed discussion is given for each topic.

  1. Use of Isotopes for Studying Reaction Mechanisms

    Indian Academy of Sciences (India)

    their positions rapidly. This is especially true of carbocations and ... Several specific examples can be quoted. Ammonia is a ... All experimental studies on this system were ... rearrangement. Hence, the species will have a relatively simple 13C.

  2. Evaluation of carbohydrate molecular mechanical force fields by quantum mechanical calculations

    DEFF Research Database (Denmark)

    Hemmingsen, Lars Bo Stegeager; Madsen, D.E.; Esbensen, A.L.

    2004-01-01

    of the (gg, gt and tg) rotamers of methyl alpha-D-glucopyranoside and methyl alpha-D-galactopyranoside are (0.13, 0.00, 0.15) and (0.64, 0.00, 0.77) kcal/mol. respectively. The results of the quantum mechanical calculations are compared with the results of calculations using the 20 second...... for monosaccharide carbohydrate benchmark systems. Selected results are: (i) The interaction energy of the alpha-D-alucopyranose-H2O heterodimer is estimated to be 4.9 kcal/mol, using a composite method including terms at highly correlated (CCSD(T)) level. Most molecular mechanics force fields are in error...

  3. Biological and mechanical evaluation of a Bio-Hybrid scaffold for autologous valve tissue engineering.

    Science.gov (United States)

    Jahnavi, S; Saravanan, U; Arthi, N; Bhuvaneshwar, G S; Kumary, T V; Rajan, S; Verma, R S

    2017-04-01

    Major challenge in heart valve tissue engineering for paediatric patients is the development of an autologous valve with regenerative capacity. Hybrid tissue engineering approach is recently gaining popularity to design scaffolds with desired biological and mechanical properties that can remodel post implantation. In this study, we fabricated aligned nanofibrous Bio-Hybrid scaffold made of decellularized bovine pericardium: polycaprolactone-chitosan with optimized polymer thickness to yield the desired biological and mechanical properties. CD44 + , αSMA + , Vimentin + and CD105 - human valve interstitial cells were isolated and seeded on these Bio-Hybrid scaffolds. Subsequent biological evaluation revealed interstitial cell proliferation with dense extra cellular matrix deposition that indicated the viability for growth and proliferation of seeded cells on the scaffolds. Uniaxial mechanical tests along axial direction showed that the Bio-Hybrid scaffolds has at least 20 times the strength of the native valves and its stiffness is nearly 3 times more than that of native valves. Biaxial and uniaxial mechanical studies on valve interstitial cells cultured Bio-Hybrid scaffolds revealed that the response along the axial and circumferential direction was different, similar to native valves. Overall, our findings suggest that Bio-Hybrid scaffold is a promising material for future development of regenerative heart valve constructs in children. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Improvement and evaluation of thermal, electrical, sealing and mechanical contacts, and their interface materials

    Science.gov (United States)

    Luo, Xiangcheng

    Material contacts, including thermal, electrical, seating (fluid sealing and electromagnetic sealing) and mechanical (pressure) contacts, together with their interface materials, were, evaluated, and in some cases, improved beyond the state of the art. The evaluation involved the use of thermal, electrical and mechanical methods. For thermal contacts, this work evaluated and improved the heat transfer efficiency between two contacting components by developing various thermal interface pastes. Sodium silicate based thermal pastes (with boron nitride particles as the thermally conductive filler) as well as polyethylene glycol (PEG) based thermal pastes were developed and evaluated. The optimum volume fractions of BN in sodium silicate based pastes and PEG based pastes were 16% and 18% respectively. The contribution of Li+ ions to the thermal contact conductance in the PEG-based paste was confirmed. For electrical contacts, the relationship between the mechanical reliability and electrical reliability of solder/copper and silver-epoxy/copper joints was addressed. Mechanical pull-out testing was conducted on solder/copper and silver-epoxy/copper joints, while the contact electrical resistivity was measured. Cleansing of the copper surface was more effective for the reliability of silver-epoxy/copper joint than that of solder/copper joint. For sealing contacts, this work evaluated flexible graphite as an electromagnetic shielding gasket material. Flexible graphite was found to be at least comparable to conductive filled silicone (the state of the art) in terms of the shielding effectiveness. The conformability of flexible graphite with its mating metal surface under repeated compression was characterized by monitoring the contact electrical resistance, as the conformability is important to both electromagnetic scaling and fluid waling using flexible graphite. For mechanical contacts, this work focused on the correlation of the interface structure (such as elastic

  5. Can legal research benefit from evaluation studies?

    Directory of Open Access Journals (Sweden)

    Frans L. Leeuw

    2011-01-01

    Full Text Available The article describes what evaluation studies have to offer to legal research. Several cases and types of evaluations are presented, in relation to legal or semi-legal questions. Also, a short overview of the contemporary history of evaluation studies is presented. Finally, it will address the question of how to ensure that in legal research and in legal training attention is paid to theories, designs and methods of evaluation studies.

  6. Non-destructive evaluation on mechanical properties of nuclear graphite with porous structure

    International Nuclear Information System (INIS)

    Shibata, Taiju; Hanawa, Satoshi; Sumita, Junya; Tada, Tatsuya; Sawa, Kazuhiro; Iyoku, Tatsuo

    2005-01-01

    As a research subjects of 'Research and development for advanced high temperature gas cooled reactor fuels and graphite components,' we started the study of development of non-destructive evaluation methods for mechanical properties of graphite components. The micro-indentation and ultrasonic wave methods are focused to evaluate the degradation of graphite components in VHTR core. For the micro-indentation method, the test apparatus was designed for the indentation test on graphite specimens with some stress levels. It is expected the stress condition is evaluated by the indentation load-depth characteristics and hardness. For the ultrasonic wave method, ultrasonic wave testing machine and probes were prepared for experiments. It is expected that the stress and inner porous conditions are evaluated by the wave propagation characteristics with wave-pore interaction model. R and D plan to develop the non-destructive evaluation method for graphite is presented in this paper. (This study is the result of contract research in the fiscal year of 2004, Research and development for advanced high temperature gas cooled reactor fuels and graphite components,' which is entrusted to the Japan Atomic Energy Research Institute from the Ministry of Education, Culture, Sports, Science and Technology of Japan.) (author)

  7. A procedure for a mechanical evaluation of an undefined osteo-protective material.

    Science.gov (United States)

    Marques, Marco; Terroso, Miguel; Freitas, Ricardo; Marques, AntÓnio Torres; Gabriel, Joaquim; Simoes, Ricardo

    2015-02-01

    Falls represent a major care and cost problem to health and social services world-widely, since 50% of falls result in an injury. In this work, is proposed a methodology to evaluate protective pads materials and geometry performance, in order to reduce impact results in a fall event. Since the material properties and the pad geometry are the key factors to make the protection possible when a fall event occurs, our approach relies on the use of mechanical tests to evaluate the properties of the material and in the study of the pad response during a fall. For this, were used compression, tensile and instrumented falling weight tests, that allow a fully characterization of the materials that can be employed in the protective pads. Likewise, to gather precise information on falls events, in order to study the pad response during a fall, a set of laboratory fall trials were created using a camera-less inertial motion capture (mocap) system. This allow the acquisition of dynamic information of falls, namely acceleration and velocity that can be used to create a finite element analysis (FEA) model, where different segments from the human body can be evaluated when the protective pad is associated to it. Through the proposed methodology, different materials and pad geometries can be studied towards maximizing the performance of protection pads for falls. The mocap system allows the acquisition of fall data, and also the creation of a human body geometrical model, representative of the fall. From the mechanical trials, was showed that the spacer fabric embedded with silicone has the higher ability to reduce the peak force in case of impact when compared with all the other specimens. The compression and the tensile tests allow the mechanical definition of the material, and with this the material definition on the FEA model. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Mechanism based evaluation of materials behavior and reference curves

    International Nuclear Information System (INIS)

    Toerroenen, K.; Saario, T.; Wallin, K.; Forsten, J.

    1984-01-01

    The safety assessment of nuclear pressure vessels and piping requires a quantitative estimation of defect growth by stable and unstable manner during service. This estimation is essential for determining whether the defect detected during inspection should be repaired or whether the size of the defect even after its expected growth is small enough to leave the integrity of the vessel unaffected. The most important stable defect growth mechanism is that of environmentally assisted cyclic crack growth. Recent results indicate that it is markedly affected by sulfur content and/or manganese sulfide morphology and distribution. This implies that an essential improvement in component safety has been gained by currently applied steelmaking practices, which result in extra low sulfur content, generally below 0.01 wt%, and in round shape and small size of inclusions, through, e.g., calcium treatment, hence considerably reducing the effect of environment on crack growth rate. This further implies that the ASME Section XI reference curves for environmentally accelerated cyclic crack growth are conservative for steels produced by current steelmaking practices. (orig./WL)

  9. A quantum mechanics/molecular mechanics study on the hydrolysis mechanism of New Delhi metallo-β-lactamase-1.

    Science.gov (United States)

    Zhu, Kongkai; Lu, Junyan; Liang, Zhongjie; Kong, Xiangqian; Ye, Fei; Jin, Lu; Geng, Heji; Chen, Yong; Zheng, Mingyue; Jiang, Hualiang; Li, Jun-Qian; Luo, Cheng

    2013-03-01

    New Delhi metallo-β-lactamase-1 (NDM-1) has emerged as a major global threat to human health for its rapid rate of dissemination and ability to make pathogenic microbes resistant to almost all known β-lactam antibiotics. In addition, effective NDM-1 inhibitors have not been identified to date. In spite of the plethora of structural and kinetic data available, the accurate molecular characteristics of and details on the enzymatic reaction of NDM-1 hydrolyzing β-lactam antibiotics remain incompletely understood. In this study, a combined computational approach including molecular docking, molecular dynamics simulations and quantum mechanics/molecular mechanics calculations was performed to characterize the catalytic mechanism of meropenem catalyzed by NDM-1. The quantum mechanics/molecular mechanics results indicate that the ionized D124 is beneficial to the cleavage of the C-N bond within the β-lactam ring. Meanwhile, it is energetically favorable to form an intermediate if no water molecule coordinates to Zn2. Moreover, according to the molecular dynamics results, the conserved residue K211 plays a pivotal role in substrate binding and catalysis, which is quite consistent with previous mutagenesis data. Our study provides detailed insights into the catalytic mechanism of NDM-1 hydrolyzing meropenem β-lactam antibiotics and offers clues for the discovery of new antibiotics against NDM-1 positive strains in clinical studies.

  10. Mechanical properties of denture base resins: An evaluation

    Directory of Open Access Journals (Sweden)

    Pooran Chand

    2011-01-01

    Conclusion: The heat cure denture base material D (Trevalon "HI" was the strongest and C (Trevalon was the weakest among all materials used in this study. The study showed that the deflection of various denture base resins (A to D increases proportionately with the increase in load.

  11. The COD concept and its application to fracture mechanical evaluation of cracked components

    International Nuclear Information System (INIS)

    Kockelmann, H.

    1984-01-01

    Based on a comprehensive literature study, this report critically evaluates the current state of experiences with the COD concept in fracture mechanics. First the concept is explained and the procedure of materials testing with a view to fracture mechanics is discussed in detail with emphasis on: The definition of crack shape modification; the procedure to detect crack modification, with subsequent comparison; the determination of material characteristics; the impact on the characteristics of the crack tip opening and the dispersion of results. The correlation between crack tip opening characteristics and notch impact strength is explained, and the methods applied for analysis of the streses affecting the structural components are shown. The design-based and failure threshold curves and the treatment of real crack geometries are also discussed. Problems still to be solved are shown. (orig./HP) [de

  12. Mechanical evaluation of quad-helix appliance made of low-nickel stainless steel wire.

    Science.gov (United States)

    dos Santos, Rogério Lacerda; Pithon, Matheus Melo

    2013-01-01

    The objective of this study was to test the hypothesis that there is no difference between stainless steel and low-nickel stainless steel wires as regards mechanical behavior. Force, resilience, and elastic modulus produced by Quad-helix appliances made of 0.032-inch and 0.036-inch wires were evaluated. Sixty Quad-helix appliances were made, thirty for each type of alloy, being fifteen for each wire thickness, 0.032-in and 0.036-in. All the archwires were submitted to mechanical compression test using an EMIC DL-10000 machine simulating activations of 4, 6, 9, and 12 mm. Analysis of variance (ANOVA) with multiple comparisons and Tukey's test were used (p nickel stainless steel alloy had force, resilience, and elastic modulus similar to those made of stainless steel alloy.

  13. Evaluation of the mechanical properties of Niobium modified cast AISI H 13 hot work tool steel

    International Nuclear Information System (INIS)

    Noorian, A.; Kheirandish, Sh.; Saghafian, H.

    2010-01-01

    In this research, the effects of partially replacing of vanadium and molybdenum with niobium on the mechanical properties of AISIH 13 hot-work tool steel have been studied. Cast samples made of the modified new steel were homogenized and austenitized at different conditions, followed by tempering at the specified temperature ranges. Hardness, red hardness, three point bending test and Charpy impact test were carried out to evaluate the mechanical properties together with characterizing the microstructure of the modified steel using scanning electron microscope. The results show that niobium addition modifies the cast structure of Nb-alloyed steel, and increases its maximum hardness. It was found that bending strength; bending strain, impact strength, and red hardness of the modified cast steel are also higher than those of the cast H13 steel, and lower than those of the wrought H13 steel.

  14. A Study of Crystalline Mechanism of Penetration Sealer Materials.

    Science.gov (United States)

    Teng, Li-Wei; Huang, Ran; Chen, Jie; Cheng, An; Hsu, Hui-Mi

    2014-01-14

    It is quite common to dispense a topping material like crystalline penetration sealer materials (CPSM) onto the surface of a plastic substance such as concrete to extend its service life span by surface protections from outside breakthrough. The CPSM can penetrate into the existing pores or possible cracks in such a way that it may form crystals to block the potential paths which provide breakthrough for any unknown materials. This study investigated the crystalline mechanism formed in the part of concrete penetrated by the CPSM. We analyzed the chemical composites, in order to identify the mechanism of CPSM and to evaluate the penetrated depth. As shown in the results, SEM observes the acicular-structured crystals filling capillary pores for mortar substrate of the internal microstructure beneath the concrete surface; meanwhile, XRD and FT-IR showed the main hydration products of CPSM to be C-S-H gel and CaCO₃. Besides, MIP also shows CPSM with the ability to clog capillary pores of mortar substrate; thus, it reduces porosity, and appears to benefit in sealing pores or cracks. The depth of CPSM penetration capability indicated by TGA shows 0-10 mm of sealer layer beneath the concrete surface.

  15. A Study of Crystalline Mechanism of Penetration Sealer Materials

    Directory of Open Access Journals (Sweden)

    Li-Wei Teng

    2014-01-01

    Full Text Available It is quite common to dispense a topping material like crystalline penetration sealer materials (CPSM onto the surface of a plastic substance such as concrete to extend its service life span by surface protections from outside breakthrough. The CPSM can penetrate into the existing pores or possible cracks in such a way that it may form crystals to block the potential paths which provide breakthrough for any unknown materials. This study investigated the crystalline mechanism formed in the part of concrete penetrated by the CPSM. We analyzed the chemical composites, in order to identify the mechanism of CPSM and to evaluate the penetrated depth. As shown in the results, SEM observes the acicular-structured crystals filling capillary pores for mortar substrate of the internal microstructure beneath the concrete surface; meanwhile, XRD and FT-IR showed the main hydration products of CPSM to be C-S-H gel and CaCO3. Besides, MIP also shows CPSM with the ability to clog capillary pores of mortar substrate; thus, it reduces porosity, and appears to benefit in sealing pores or cracks. The depth of CPSM penetration capability indicated by TGA shows 0–10 mm of sealer layer beneath the concrete surface.

  16. The Breast Health Intervention Evaluation Study

    National Research Council Canada - National Science Library

    Blumenthal, Daniel

    1997-01-01

    The Breast Health Intervention Evaluation (BRIE) Study will evaluate the relative effectiveness of three different approaches to breast health messages--a fear appeal, a positive affect appeal, and an affectively neutral, cognitive appeal...

  17. Crescent Evaluation : appendix B : state case study evaluation report

    Science.gov (United States)

    1994-02-01

    The state case study evaluation approach uniquely captured an understanding of the potential of such a system by documenting the experiences, issues, and opportunities of selected key state government personnel from a cross-section of involved agenci...

  18. Utility of cardiac computed tomography for evaluation of pannus in mechanical aortic valve.

    Science.gov (United States)

    Suh, Young Joo; Kim, Young Jin; Lee, Sak; Hong, Yoo Jin; Lee, Hye-Jeong; Hur, Jin; Choi, Byoung Wook; Chang, Byung-Chul

    2015-08-01

    The clinical significance of pannus detected on computed tomography (CT) has not yet been investigated. The purposes of this study were to investigate the clinical significance of pannus detected on cardiac CT in patients who underwent aortic valve replacement (AVR) with mechanical valves, and to determine predictors for pannus severity. A total of 92 patients who underwent cardiac CT and TTE and who had undergone mechanical AVR were included. The geometric orifice area (GOA), the presence of limitation of motion (LOM) and pannus were evaluated on CT. The GOA, presence of LOM, and presence and severity of pannus were compared with echocardiographic parameters. Logistic regression analysis was performed to determine the predictors for pannus severity. The GOA on CT positively correlated with effective orifice area on TTE (r = 0.733, P Pannus was found in 77.2% and LOM in 14.0%. With increasing pannus severity, mean transvalvular pressure gradient (PG) was significantly higher (P pannus, more severe pannus and LOM than patients with normal PG (P pannus (P pannus formation in patients with mechanical aortic valves. Moderate to severe pannus formation frequently occurred in patients with small mechanical valve size, Carbomedics valves, rheumatic heart disease and young age at AVR.

  19. Comparative Evaluations and Microstructure: Mechanical Property Relations of Sintered Silicon Carbide Consolidated by Various Techniques

    Science.gov (United States)

    Barick, Prasenjit; Chatterjee, Arya; Majumdar, Bhaskar; Saha, Bhaskar Prasad; Mitra, Rahul

    2018-04-01

    A comparative evaluation between pressureless or self-sintered silicon carbide (SSiC), hot-pressed silicon carbide (HP-SiC), and spark plasma-sintered silicon carbide (SPS-SiC) has been carried out with emphasis on examination of their microstructures and mechanical properties. The effect of sample dimensions on density and properties of SPS-SiC has been also examined. Elastic modulus, flexural strength, and fracture toughness measured by indentation or testing of single-edge notched beam specimens have been found to follow the following trend, HP-SiC > SSiC > SPS-SiC. The SPS-SiC samples have shown size-dependent densification and mechanical properties, with the smaller sample exhibiting superior properties. The mechanical properties of sintered SiC samples appear to be influenced by relative density, grain size, and morphology, as well as the existence of intergranular glassy phase. Studies of fracture surface morphologies have revealed the mechanism of failure to be transgranular in SSiC or HP-SiC, and intergranular in case of SPS-SiC, indicating the dominating influence of grain size and α-SiC formation with high aspect ratio.

  20. A recoil resilient lumen support, design, fabrication and mechanical evaluation

    Science.gov (United States)

    Mehdizadeh, Arash; Ali, Mohamed Sultan Mohamed; Takahata, Kenichi; Al-Sarawi, Said; Abbott, Derek

    2013-06-01

    Stents are artificial implants that provide scaffolding to a cavity inside the body. This paper presents a new luminal device for reducing the mechanical failure of stents due to recoil, which is one of the most important issues in stenting. This device, which we call a recoil-resilient ring (RRR), is utilized standalone or potentially integrated with existing stents to address the problem of recoil. The proposed structure aims to minimize the need for high-pressure overexpansion that can induce intra-luminal trauma and excess growth of vascular tissue causing later restenosis. The RRR is an overlapped open ring with asymmetrical sawtooth structures that are intermeshed. These teeth can slide on top of each other, while the ring is radially expanded, but interlock step-by-step so as to keep the final expanded state against compressional forces that normally cause recoil. The RRRs thus deliver balloon expandability and, when integrated with a stent, bring both radial rigidity and longitudinal flexibility to the stent. The design of the RRR is investigated through finite element analysis (FEA), and then the devices are fabricated using micro-electro-discharge machining of 200-µm-thick Nitinol sheet. The standalone RRR is balloon expandable in vitro by 5-7 Atm in pressure, which is well within the recommended in vivo pressure ranges for stenting procedures. FEA compression tests indicate 13× less reduction of the cross-sectional area of the RRR compared with a typical stainless steel stent. These results also show perfect elastic recovery of the RRR after removal of the pressure compared to the remaining plastic deformations of the stainless steel stent. On the other hand, experimental loading tests show that the fabricated RRRs have 2.8× radial stiffness compared to a two-column section of a commercial stent while exhibiting comparable elastic recovery. Furthermore, testing of in vitro expansion in a mock artery tube shows around 2.9% recoil, approximately 5-11

  1. A recoil resilient lumen support, design, fabrication and mechanical evaluation

    International Nuclear Information System (INIS)

    Mehdizadeh, Arash; Al-Sarawi, Said; Abbott, Derek; Ali, Mohamed Sultan Mohamed; Takahata, Kenichi

    2013-01-01

    Stents are artificial implants that provide scaffolding to a cavity inside the body. This paper presents a new luminal device for reducing the mechanical failure of stents due to recoil, which is one of the most important issues in stenting. This device, which we call a recoil-resilient ring (RRR), is utilized standalone or potentially integrated with existing stents to address the problem of recoil. The proposed structure aims to minimize the need for high-pressure overexpansion that can induce intra-luminal trauma and excess growth of vascular tissue causing later restenosis. The RRR is an overlapped open ring with asymmetrical sawtooth structures that are intermeshed. These teeth can slide on top of each other, while the ring is radially expanded, but interlock step-by-step so as to keep the final expanded state against compressional forces that normally cause recoil. The RRRs thus deliver balloon expandability and, when integrated with a stent, bring both radial rigidity and longitudinal flexibility to the stent. The design of the RRR is investigated through finite element analysis (FEA), and then the devices are fabricated using micro-electro-discharge machining of 200-µm-thick Nitinol sheet. The standalone RRR is balloon expandable in vitro by 5–7 Atm in pressure, which is well within the recommended in vivo pressure ranges for stenting procedures. FEA compression tests indicate 13× less reduction of the cross-sectional area of the RRR compared with a typical stainless steel stent. These results also show perfect elastic recovery of the RRR after removal of the pressure compared to the remaining plastic deformations of the stainless steel stent. On the other hand, experimental loading tests show that the fabricated RRRs have 2.8× radial stiffness compared to a two-column section of a commercial stent while exhibiting comparable elastic recovery. Furthermore, testing of in vitro expansion in a mock artery tube shows around 2.9% recoil, approximately 5

  2. Mechanism-based drug exposure classification in pharmacoepidemiological studies

    NARCIS (Netherlands)

    Verdel, B.M.

    2010-01-01

    Mechanism-based classification of drug exposure in pharmacoepidemiological studies In pharmacoepidemiology and pharmacovigilance, the relation between drug exposure and clinical outcomes is crucial. Exposure classification in pharmacoepidemiological studies is traditionally based on

  3. Experimental evaluation of air distribution in mechanically ventilated residential rooms

    DEFF Research Database (Denmark)

    Tomasi, R.; Krajčík, M.; Simone, A.

    2013-01-01

    The effect of low ventilation rates (1 or 0.5 air change per hour) on thermal comfort and ventilation effectiveness was experimentally studied in a simulated residential room equipped with radiant floor heating/cooling and mixing ventilation systems. The tests were performed for various positions...... of supply and extract air terminals and different winter and summer boundary conditions. Vertical air temperature, operative temperature and air velocity profiles were measured in different positions in the room, and equivalent temperatures were derived, in order to characterize thermal comfort. Contaminant...... with unconditioned outdoor air supply, i.e. at the supply air temperatures higher than the room air temperature. Moreover, low floor temperatures were needed to maintain the desired reference temperature in the stratified thermal environment. Mainly in cooling conditions the ventilation effectiveness depended...

  4. Experimental Evaluation of the Transport Mechanisms of PoIFN-α in Caco-2 Cells

    Directory of Open Access Journals (Sweden)

    Xin Liu

    2017-11-01

    Full Text Available For the development of an efficient intestinal delivery system for Porcine interferon-α (PoIFN-α, the understanding of transport mechanisms of which in the intestinal cell is essential. In this study, we investigated the absorption mechanisms of PoIFN-α in intestine cells. Caco-2 cells and fluorescein isothiocyanate-labeled (FITC-PoIFN-α were used to explore the whole transport process, including endocytosis, intracellular trafficking, exocytosis, and transcytosis. Via various techniques, the transport pathways of PoIFN-α in Caco-2 cells and the mechanisms were clarified. Firstly, the endocytosis of PoIFN-α by Caco-2 cells was time, concentration and temperature dependence. And the lipid raft/caveolae endocytosis was the most likely endocytic pathway for PoIFN-α. Secondly, both Golgi apparatus and lysosome were involved in the intracellular trafficking of PoIFN-α. Thirdly, the treatment of indomethacin resulted in a significant decrease of exocytosis of PoIFN-α, indicating the participation of cyclooxygenase. Finally, to evaluate the efficiency of PoIFN-α transport, the transepithelial electrical resistance (TEER value was measured to investigate the tight junctional integrity of the cell monolayers. The fluorescence microscope results revealed that the transport of PoIFN-α across the Caco-2 cell monolayers was restricted. In conclusion, this study depicts a probable picture of PoIFN-α transport in Caco-2 cells characterized by non-specificity, partial energy-dependency and low transcytosis.

  5. The use of fracture mechanics for the evaluation of NDE flaw acceptance standards

    Energy Technology Data Exchange (ETDEWEB)

    Alicino, A; Capurro, E; Ansaldo, Sp; Corvi, A [Ansaldo SpA, Genoa (Italy)

    1988-12-31

    This document deals with the use of fracture mechanics criteria to evaluate the Non Destructive Examination (NDE) flaw acceptance standards. The communication discusses the general schemes and the guidelines of the activity carried out. (TEC).

  6. Study design considerations in evaluating environmental impacts

    Science.gov (United States)

    Stan T. Lebow; Paul A. Cooper; Patricia Lebow

    2006-01-01

    The purpose of this chapter is to make the reader aware of how choices in study parameters may influence the outcome of treated-wood environmental impact evaluations. Evaluation of the leaching and environmental accumulation of preservatives from treated wood is a complex process. and many factors can influence the results of such studies. In laboratory studies, the...

  7. Chlorination of tramadol: Reaction kinetics, mechanism and genotoxicity evaluation.

    Science.gov (United States)

    Cheng, Hanyang; Song, Dean; Chang, Yangyang; Liu, Huijuan; Qu, Jiuhui

    2015-12-01

    Tramadol (TRA) is one of the most detected analgesics in environmental matrices, and it is of high significance to study the reactivity of TRA during chlorination considering its potential toxicity to the environment. The chlorine/TRA reaction is first order with respect to the TRA concentration, and a combination of first-order and second-order with respect to chlorine concentration. The pH dependence of the observed rate constants (kobs) showed that the TRA oxidation reactivity increased with increasing pH. kobs can be quantitatively described by considering all active species including Cl2, Cl2O and HOCl, and the individual rate constants of HOCl/TRA(0), HOCl/TRAH(+), Cl2/TRA and Cl2O/TRA reactions were calculated to be (2.61±0.29)×10(3)M(-1)s(-1), 14.73±4.17M(-1)s(-1), (3.93±0.34)×10(5)M(-1)s(-1) and (5.66±1.83)×10(6)M(-1)s(-1), respectively. Eleven degradation products were detected with UPLC-Q-TOF-MS, and the corresponding structures of eight products found under various pH conditions were proposed. The amine group was proposed to be the initial attack site under alkaline pH conditions, where reaction of the deprotonated amine group with HOCl is favorable. Under acidic and neutral pH conditions, however, two possible reaction pathways were proposed. One is an electrophilic substitution on the aromatic ring, and another is an electrophilic substitution on the nitrogen, leading to an N-chlorinated intermediate, which can be further oxidized. Finally, the SOS/umu test showed that the genotoxicity of TRA chlorination products increased with increasing dosage of chlorine, which was mostly attributed to the formation of some chlorine substitution products. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Mechanical Integrity of Copper Canister Lid and Cylinder. Sensitivity study

    International Nuclear Information System (INIS)

    Karlsson, Marianne

    2002-08-01

    This report is part of a study of the mechanical integrity of canisters used for disposal of nuclear fuel waste. The overall objective is to determine and ensure the static and long-term strength of the copper canister lid and cylinder casing. The canisters used for disposal nuclear fuel waste of type BWR consists of an inner part (insert) of ductile cast iron and an outer part of copper. The copper canister is to provide a sealed barrier between the contents of the canister and the surroundings. The study in this report complements the finite element analyses performed in an earlier study. The analyses aim to evaluate the sensitivity of the canister to tolerances regarding the gap between the copper cylinder and the cast iron insert. Since great uncertainties regarding the material's long term creep properties prevail, analyses are also performed to evaluate the effect of different creep data on the resulting strain and stress state. The report analyses the mechanical response of the lid and flange of the copper canister when subjected to loads caused by pressure from swelling bentonite and from groundwater at a depth of 500 meter. The loads acting on the canister are somewhat uncertain and the cases investigated in this report are possible cases. Load cases analysed are: Pressure 15 MPa uniformly distributed on lid and 5 MPa uniformly distributed on cylinder; Pressure 5 MPa uniformly distributed on lid and 15 MPa uniformly distributed on cylinder; Pressure 20 MPa uniformly distributed on lid and cylinder; and Side pressures 10 MPa and 20 MPa uniformly distributed on part of the cylinder. Creep analyses are performed for two of the load cases. For all considered designs high principal stresses appear on the outside of the copper cylinder in the region from the weld down to the level of the lid lower edge. Altering the gap between lid and cylinder and/or between cylinder and insert only marginally affects the resulting stress state. Fitting the lid in the cylinder

  9. The quality evaluation of frankfurter-type sausages from hand and mechanically deboned turkey meat.

    Science.gov (United States)

    Radomyski, T; Niewiarowicz, A

    1987-03-01

    A quality evaluation was made of frankfurter-type sausages made from hand and mechanically deboned meat from various parts of turkey carcasses. The results led to the conclusions that despite some differences in objective measurements of the sausage quality, mechanically deboned turkey meat can be considered as an exclusive meat raw material for the production of frankfurter-type sausages. The quality of sausages from mechanically deboned turkey meat from wings and frames with skin was the least satisfactory.

  10. Space Mechanisms Lessons Learned and Accelerated Testing Studies

    Science.gov (United States)

    Fusaro, Robert L.

    1997-01-01

    A number of mechanism (mechanical moving component) failures and anomalies have recently occurred on satellites. In addition, more demanding operating and life requirements have caused mechanism failures or anomalies to occur even before some satellites were launched (e.g., during the qualification testing of GOES-NEXT, CERES, and the Space Station Freedom Beta Joint Gimbal). For these reasons, it is imperative to determine which mechanisms worked in the past and which have failed so that the best selection of mechanically moving components can be made for future satellites. It is also important to know where the problem areas are so that timely decisions can be made on the initiation of research to develop future needed technology. To chronicle the life and performance characteristics of mechanisms operating in a space environment, a Space Mechanisms Lessons Learned Study was conducted. The work was conducted by the NASA Lewis Research Center and by Mechanical Technologies Inc. (MTI) under contract NAS3-27086. The expectation of the study was to capture and retrieve information relating to the life and performance of mechanisms operating in the space environment to determine what components had operated successfully and what components had produced anomalies.

  11. Evaluation of the predictors for duration of mechanical ventilation in respiratory intensive care unit

    Directory of Open Access Journals (Sweden)

    Hira H

    2006-01-01

    Full Text Available Background: Mechanical ventilation (MV is a life saving modality. Till no method is evolved to predict the duration of this treatment. This study is undertaken to evaluate the clinical and laboratory parameters at initiation and 48 hour of the patient being treated by mechanical ventilation; and correlate these parameters with the duration of MV required. Methods: It was prospective observational study conducted in the respiratory intensive care unit (RICU of a tertiary referral and teaching hospital. Thirty consecutive patients suffering from various medical diseases requiring MV were the participants. Clinical, laboratory, ventilatory parameters and six severity scores viz.; GCS, APACHE-II, SAPS, OSF, ALI/ARDS and Sepsis/Septic shock criteria of each patient, both at initiation and at 48 hour of MV were recorded. Correlation between various severity scores at initiation and at 48 hour of initiation with duration of mechanical ventilation was computed. Results: Based on the duration of mechanical ventilation required, the patients were divided in two groups. Those requiring mechanical ventilation < 7 days and> 7 days were designated Group I and Group II respectively. Three out of 6 severity scores (GCS, APACHE-II, SAPS recorded at 48 hour of MV showed statistically significant difference between the both groups with p value of 0.010, 0.009 and 0.006 respectively. Further stepwise logistic regression analysis showed that SAPS score at 48 hour of initiation was the best predictor of duration of MV. It was found that a cut off value of 15 for SAPS score at 48 hour might predict the duration of MV i.e. < 7days or> 7 days. Based on linear regression analysis a simple equation was formulated by putting the SAPS value at 48 hour, the value of Y was computed. If MV required was less than 7 days, the value of Y was more than - 0.172 and if need of mechanical ventilation was more than 7 days, Y was less than -0.1720. Conclusions: For patients requiring

  12. Evaluation of Thermal and Thermo-mechanical Behavior of Full-scale Energy Foundations

    Science.gov (United States)

    Murphy, Kyle D.

    This study focuses on the thermo-mechanical and thermal behavior of full-scale energy foundations installed as part of two buildings recently constructed in Colorado. The soil stratigraphy at each of the sites differed, but both foundations were expected to function as primarily end-bearing elements with a tip socketed into rock. The heat exchanger configurations were also different amongst the foundations at both sites, permitting evaluation of the role of heat exchange. A common thread for both energy foundation case histories was the monitoring of the temperature and axial strain within the foundations during heat exchange operations. The first case study involves an evaluation of the long-term thermo-mechanical response of two full-scale energy foundations installed at the new Denver Housing Authority (DHA) Senior Living Facility at 1099 Osage St. in Denver, Colorado. Due to the construction schedule for this project, the thermal properties of the foundations and surrounding subsurface could not be assessed using thermal response tests. However, instrumentation was incorporated into the foundations to assess their long-term heat exchange response as well as the thermo-mechanical strains, stresses, and displacements that occurred during construction and operation of the ground-source heat pump system. The temperature changes within the foundations during heating and cooling operations over a period of approximately 600 days ranged from 9 to 32 °C, respectively. The thermal axial stresses in the foundations were calculated from the measured strains, and ranged from 3.1 MPa during heating to --1.0 MPa during cooling. These values are within reasonable limits for reinforced concrete structures. The maximum thermal axial stress was observed near the toe of both foundations, which is consistent with trends expected for end-bearing toe boundary conditions. The greatest thermal axial strains were observed near the top of the foundations (upward expansion during

  13. Evaluating Evaluation Systems: Policy Levers and Strategies for Studying Implementation of Educator Evaluation. Policy Snapshot

    Science.gov (United States)

    Matlach, Lauren

    2015-01-01

    Evaluation studies can provide feedback on implementation, support continuous improvement, and increase understanding of evaluation systems' impact on teaching and learning. Despite the importance of educator evaluation studies, states often need support to prioritize and fund them. Successful studies require expertise, time, and a shared…

  14. Seismic performance evaluation of high natural frequency mechanical structure from the viewpoint of energy balance

    International Nuclear Information System (INIS)

    Minagawa, Keisuke; Fujita, Satoshi; Endo, Rokuro; Amemiya, Mitsuhiko

    2009-01-01

    In this study, vibration characteristics of mechanical structure having high natural frequency are investigated from the viewpoint of energy balance. Mechanical structures having high natural frequency in a nuclear power plant are generally designed statically and elastically. However it has been reported that fracture of ordinary piping is produced not by momentary large load but by cumulative fatigue damage. Therefore it is very important to grasp seismic performance dynamically by considering cyclic load. This paper deals with an investigation regarding seismic performance evaluation of high natural frequency mechanical structure. The energy balance equation that is one of valid methods for structural calculation is applied through the investigation. The main feature of the energy balance equation is that it explains accumulated information of motion. Therefore the energy balance equation is adequate for the investigation of the influence of cumulative load such as seismic response. In this paper, vibration experiment and simulation using sinusoidal waves and artificial seismic waves were examined in order to investigate relationship between natural frequency of structure and energy. As a result, we found that input energy decreases with an increase in the natural frequency. (author)

  15. Implementation of Statistical Process Control: Evaluating the Mechanical Performance of a Candidate Silicone Elastomer Docking Seal

    Science.gov (United States)

    Oravec, Heather Ann; Daniels, Christopher C.

    2014-01-01

    The National Aeronautics and Space Administration has been developing a novel docking system to meet the requirements of future exploration missions to low-Earth orbit and beyond. A dynamic gas pressure seal is located at the main interface between the active and passive mating components of the new docking system. This seal is designed to operate in the harsh space environment, but is also to perform within strict loading requirements while maintaining an acceptable level of leak rate. In this study, a candidate silicone elastomer seal was designed, and multiple subscale test articles were manufactured for evaluation purposes. The force required to fully compress each test article at room temperature was quantified and found to be below the maximum allowable load for the docking system. However, a significant amount of scatter was observed in the test results. Due to the stochastic nature of the mechanical performance of this candidate docking seal, a statistical process control technique was implemented to isolate unusual compression behavior from typical mechanical performance. The results of this statistical analysis indicated a lack of process control, suggesting a variation in the manufacturing phase of the process. Further investigation revealed that changes in the manufacturing molding process had occurred which may have influenced the mechanical performance of the seal. This knowledge improves the chance of this and future space seals to satisfy or exceed design specifications.

  16. Evaluation of the user interface simplicity in the modern generation of mechanical ventilators.

    Science.gov (United States)

    Uzawa, Yoshihiro; Yamada, Yoshitsugu; Suzukawa, Masayuki

    2008-03-01

    We designed this study to evaluate the simplicity of the user interface in modern-generation mechanical ventilators. We hypothesized that different designs in the user interface could result in different rates of operational failures. A laboratory in a tertiary teaching hospital. Crossover design. Twenty-one medical resident physicians who did not possess operating experience with any of the selected ventilators. Four modern mechanical ventilators were selected: Dräger Evita XL, Maquet Servo-i, Newport e500, and Puritan Bennett 840. Each subject was requested to perform 8 tasks on each ventilator. Two objective variables (the number of successfully completed tasks without operational failures and the operational time) and the overall subjective rating of the ease of use, measured with a 100-mm visual analog scale were recorded. The total percentage of operational failures made for all subjects, for all tasks, was 23%. There were significant differences in the rates of operational failures and operational time among the 4 ventilators. Subjects made more operational failures in setting up the ventilators and in making ventilator-setting changes than in reacting to alarms. The subjective feeling of the ease of use was also significantly different among the ventilators. The design of the user interface is relevant to the occurrence of operational failures. Our data indicate that ventilator designers could optimize the user-interface design to reduce the operational failures; therefore, basic user interface should be standardized among the clinically used mechanical ventilators.

  17. Mechanical and cytotoxicity evaluation of nanostructured hydroxyapatite-bredigite scaffolds for bone regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Eilbagi, Marjan; Emadi, Rahmatollah; Raeissi, Keyvan [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Kharaziha, Mahshid, E-mail: ma.kharaziha@gmail.com [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Valiani, Ali [Department of Anatomical Sciences, School of Medicine, Isfahan University of Medical Sciences, Isfahan 81746-73441 (Iran, Islamic Republic of)

    2016-11-01

    Despite the attractive characteristics of three-dimensional pure hydroxyapatite (HA) scaffolds, due to their weak mechanical properties, researches have focused on the development of composite scaffolds via introducing suitable secondary components. The aim of this study was to develop, for the first time, three-dimensional HA-bredigite (Ca{sub 7}MgSi{sub 4}O{sub 16}) scaffolds containing various amounts of bredigite nanopowder (0, 5, 10 and 15 wt.%) using space holder technique. Transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction spectroscopy were applied in order to study the morphology, fracture surface and phase compositions of nanopowders and scaffolds. Furthermore, the effects of scaffold composition on the mechanical properties, bioactivity, biodegradability, and cytotoxicity were also evaluated. Results showed that the composite scaffolds with average pore size in the range of 220–310 μm, appearance porosity of 63.1–75.9% and appearance density of 1.1 ± 0.04 g/cm{sup 3} were successfully developed, depending on bredigite content. Indeed, the micropore size of the scaffolds reduced with increasing bredigite content confirming that the sinterability of the scaffolds was improved. Furthermore, the compression strength and modulus of the scaffolds significantly enhanced via incorporation of bredigite content from 0 to 15 wt.%. The composite scaffolds revealed superior bioactivity and biodegradability with increasing bredigite content. Moreover, MTT assay confirmed that HA-15 wt.% bredigite scaffold significantly promoted cell proliferation compared to tissue culture plate (control) and HA scaffold. Based on these results, three-dimensional HA-bredigite scaffolds could be promising replacements for HA scaffolds in bone regeneration. - Highlights: • Nanostructured hydroxyapatite-bredigite composite scaffolds were developed using space holder technique. • Presence of bredigite

  18. Exocytosis: using amperometry to study presynaptic mechanisms of neurotoxicity

    NARCIS (Netherlands)

    Westerink, R.H.S.

    2004-01-01

    The development of carbon fiber microelectrode amperometry enabled detailed investigation of the presynaptic response at the single cell level with single vesicle resolution. Consequently, amperometry allowed for detailed studies into the presynaptic mechanisms underlying neurotoxicity. This review

  19. Defect-related internal dissipation in mechanical resonators and the study of coupled mechanical systems.

    Energy Technology Data Exchange (ETDEWEB)

    Friedmann, Thomas Aquinas; Czaplewski, David A.; Sullivan, John Patrick; Modine, Normand Arthur; Wendt, Joel Robert; Aslam, Dean (Michigan State University, Lansing, MI); Sepulveda-Alancastro, Nelson (University of Puerto Rico, Mayaguez, PR)

    2007-01-01

    Understanding internal dissipation in resonant mechanical systems at the micro- and nanoscale is of great technological and fundamental interest. Resonant mechanical systems are central to many sensor technologies, and microscale resonators form the basis of a variety of scanning probe microscopies. Furthermore, coupled resonant mechanical systems are of great utility for the study of complex dynamics in systems ranging from biology to electronics to photonics. In this work, we report the detailed experimental study of internal dissipation in micro- and nanomechanical oscillators fabricated from amorphous and crystalline diamond materials, atomistic modeling of dissipation in amorphous, defect-free, and defect-containing crystalline silicon, and experimental work on the properties of one-dimensional and two-dimensional coupled mechanical oscillator arrays. We have identified that internal dissipation in most micro- and nanoscale oscillators is limited by defect relaxation processes, with large differences in the nature of the defects as the local order of the material ranges from amorphous to crystalline. Atomistic simulations also showed a dominant role of defect relaxation processes in controlling internal dissipation. Our studies of one-dimensional and two-dimensional coupled oscillator arrays revealed that it is possible to create mechanical systems that should be ideal for the study of non-linear dynamics and localization.

  20. Women's Studies Collections: A Checklist Evaluation

    Science.gov (United States)

    Bolton, Brooke A.

    2009-01-01

    A checklist evaluation on thirty-seven Women's Studies programs conducted using the individual institutions' online public access catalogs (OPACs) is presented. Although Women's Studies collections are very difficult to build, an evaluation of existing programs shows that collections, for the most part, have managed substantial coverage of the…

  1. Precision toxicology based on single cell sequencing: an evolving trend in toxicological evaluations and mechanism exploration.

    Science.gov (United States)

    Zhang, Boyang; Huang, Kunlun; Zhu, Liye; Luo, Yunbo; Xu, Wentao

    2017-07-01

    In this review, we introduce a new concept, precision toxicology: the mode of action of chemical- or drug-induced toxicity can be sensitively and specifically investigated by isolating a small group of cells or even a single cell with typical phenotype of interest followed by a single cell sequencing-based analysis. Precision toxicology can contribute to the better detection of subtle intracellular changes in response to exogenous substrates, and thus help researchers find solutions to control or relieve the toxicological effects that are serious threats to human health. We give examples for single cell isolation and recommend laser capture microdissection for in vivo studies and flow cytometric sorting for in vitro studies. In addition, we introduce the procedures for single cell sequencing and describe the expected application of these techniques to toxicological evaluations and mechanism exploration, which we believe will become a trend in toxicology.

  2. Evaluation of the Knowledge Management Mechanisms of Brazilian Northeast Universities Hospital Portals

    Directory of Open Access Journals (Sweden)

    Helio Roberto Hekis

    2013-12-01

    Full Text Available Hospital portals that manage health related data are becoming increasingly popular since they play an important role to provide, acquire and exchange information to its users. This study aims to verify how the hospital portals are contributing to the expansion of users knowledge by the analysis of interactive features associated with three mechanisms of knowledge management: Knowledge Access (KA; Knowledge Creation (KC; and Knowledge Transfer (KT. The study is exploratory, descriptive and qualitative, classified as a survey, and involves the standardization of data collection instruments (questionnaires and interviews applied directly to people of a particular population to evaluate the knowledge management the portals present on the university hospitals from northeastern of Brazil. The results indicated that the proceeds of access to knowledge (AK prevailed over other confirming the results found on the Asians and Americans hospital portals. 

  3. Evaluations of Mechanisms for Pu Uptake and Retention within Spherical Resorcinol-Formaldehyde Resin Columns

    Energy Technology Data Exchange (ETDEWEB)

    Delegard, Calvin H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Levitskaia, Tatiana G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Fiskum, Sandra K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-09-15

    The unexpected uptake and retention of plutonium (Pu) onto columns containing spherical resorcinol-formaldehyde (sRF) resin during ion exchange testing of Cs (Cs) removal from alkaline tank waste was observed in experiments at both the Pacific Northwest National Laboratory (PNNL) and the Savannah River National Laboratory (SRNL). These observations have raised concern regarding the criticality safety of the Cs removal unit operation within the low-activity waste pretreatment system (LAWPS). Accordingly, studies have been initiated at Washington River Protection Solutions (WRPS), who manages the operations of the Hanford Site tank farms, including the LAWPS, PNNL, and elsewhere to investigate these findings. As part of these efforts, PNNL has prepared the present report to summarize the laboratory testing observations, evaluate these phenomena in light of published and unpublished technical information, and outline future laboratory testing, as deemed appropriate based on the literature studies, with the goal to elucidate the mechanisms for the observed Pu uptake and retention.

  4. Relevance of Electrical Remodeling in Human Atrial Fibrillation Results of the Asymptomatic Atrial Fibrillation and Stroke Evaluation in Pacemaker Patients and the Atrial Fibrillation Reduction Atrial Pacing Trial Mechanisms of Atrial Fibrillation Study

    NARCIS (Netherlands)

    Healey, Jeff S.; Israel, Carsten W.; Connolly, Stuart J.; Hohnloser, Stefan H.; Nair, Girish M.; Divakaramenon, Syamkumar; Capucci, Alessandro; Van Gelder, Isabelle C.; Lau, Chu-Pak; Gold, Michael R.; Carlson, Mark; Themeles, Ellison; Morillo, Carlos A.

    Background-In animal models of atrial fibrillation (AF), changes in atrial electrophysiological properties are associated with the development of AF. Their relevance to human AF is unclear. Methods and Results-The Asymptomatic Atrial Fibrillation and Stroke Evaluation in Pacemaker Patients and the

  5. Handbook for evaluation studies in virtual reality

    DEFF Research Database (Denmark)

    Livatino, Salvatore; Koeffel, Christina

    2006-01-01

    of human behavior including aspects of perception, action, and task-performance. The evaluation issue calls for multi- and interdisciplinary research activities, where technical expertise is combined with humanistic knowledge and methodology. Several experts in the field of VR as well as in the field...... in evaluation studies as well as students. The aim is also to facilitate multi-disciplinary activities through the use of an evaluation handbook which would be simple and focused on VR. The applicability of this guideline has been tested in two pilot studies, which showed how this handbook could successfully...... be employed to carry out pilot (and formal) evaluations....

  6. Study on team evaluation. Team process model for team evaluation

    International Nuclear Information System (INIS)

    Sasou Kunihide; Ebisu, Mitsuhiro; Hirose, Ayako

    2004-01-01

    Several studies have been done to evaluate or improve team performance in nuclear and aviation industries. Crew resource management is the typical example. In addition, team evaluation recently gathers interests in other teams of lawyers, medical staff, accountants, psychiatrics, executive, etc. However, the most evaluation methods focus on the results of team behavior that can be observed through training or actual business situations. What is expected team is not only resolving problems but also training younger members being destined to lead the next generation. Therefore, the authors set the final goal of this study establishing a series of methods to evaluate and improve teams inclusively such as decision making, motivation, staffing, etc. As the first step, this study develops team process model describing viewpoints for the evaluation. The team process is defined as some kinds of power that activate or inactivate competency of individuals that is the components of team's competency. To find the team process, the authors discussed the merits of team behavior with the experienced training instructors and shift supervisors of nuclear/thermal power plants. The discussion finds four team merits and many components to realize those team merits. Classifying those components into eight groups of team processes such as 'Orientation', 'Decision Making', 'Power and Responsibility', 'Workload Management', 'Professional Trust', 'Motivation', 'Training' and 'staffing', the authors propose Team Process Model with two to four sub processes in each team process. In the future, the authors will develop methods to evaluate some of the team processes for nuclear/thermal power plant operation teams. (author)

  7. Insights into the catalytic mechanism of dehydrogenase BphB: A quantum mechanics/molecular mechanics study.

    Science.gov (United States)

    Zhang, Ruiming; Shi, Xiangli; Sun, Yanhui; Zhang, Qingzhu; Wang, Wenxing

    2018-05-17

    The present study delineated the dehydrogenation mechanism of cis-2,3-dihydro-2,3-dihydroxybiphenyl (2,3-DDBPH) and cis-2,3-dihydro-2,3-dihydroxy-4,4'-dichlorobiphenyl (2,3-DD-4,4'-DBPH) by Pandoraea pnomenusa strain B-356 cis-2,3-dihydro-2,3-dihydroxybiphenyl dehydrogenase (BphB) in atomistic detail. The enzymatic process was investigated by a combined quantum mechanics/molecular mechanics (QM/MM) approach. Five different snapshots were extracted and calculated, which revealed that the Boltzmann-weighted average barriers of 2,3-DDBPH and 2,3-DD-4,4'-DBPH dehydrogenation processes are 10.7 and 11.5 kcal mol -1 , respectively. The established dehydrogenation mechanism provides new insight into the degradation processes of other chlorinated 2,3-DDBPH. In addition to Asn115, Ser142, and Lys149, the importance of Ile 89, Asn143, Pro184, Met 187, Thr189, and Lue 191 during the dehydrogenation process of 2,3-DDBPH and 2,3-DD-4,4'-DBPH were also highlighted to search for promising mutation targets for improving the catalytic efficiency of BphB. Copyright © 2018. Published by Elsevier Ltd.

  8. Mechanical and toxicological evaluation of concrete artifacts containing waste foundry sand.

    Science.gov (United States)

    Mastella, Miguel Angelo; Gislon, Edivelton Soratto; Pelisser, Fernando; Ricken, Cláudio; da Silva, Luciano; Angioletto, Elídio; Montedo, Oscar Rubem Klegues

    2014-08-01

    The creation of metal parts via casting uses molds that are generally made from sand and phenolic resin. The waste generated after the casting process is called waste foundry sand (WFS). Depending on the mold composition and the casting process, WFS can contain substances that prevent its direct emission to the environment. In Brazil, this waste is classified according to the Standard ABNT NBR 10004:2004 as a waste Class II (Non-Inert). The recycling of this waste is limited because its characteristics change significantly after use. Although the use (or reuse) of this byproduct in civil construction is a technically feasible alternative, its effects must be evaluated, especially from mechanical and environmental points of view. Thus, the objective of this study is to investigate the effect of the use of WFS in the manufacture of cement artifacts, such as masonry blocks for walls, structural masonry blocks, and paving blocks. Blocks containing different concentrations of WFS (up to 75% by weight) were produced and evaluated using compressive strength tests (35 MPa at 28 days) and toxicity tests on Daphnia magna, Allium cepa (onion root), and Eisenia foetida (earthworm). The results showed that there was not a considerable reduction in the compressive strength, with values of 35 ± 2 MPa at 28 days. The toxicity study with the material obtained from leaching did not significantly interfere with the development of D. magna and E. foetida, but the growth of the A. cepa species was reduced. The study showed that the use of this waste in the production of concrete blocks is feasible from both mechanical and environmental points of view. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. EVALUATION OF ELASTICITY AND MECHANICAL PROPERTIES OF BREAD DOUGH MADE WITH REPLACED FLOUR POTATO (IPOMOEA BATATA

    Directory of Open Access Journals (Sweden)

    Ely Fernando Sacón Vera

    2016-10-01

    Full Text Available The effect of the incorporation of sweet potato flour, with 30% replacement in 1kg of wheat flour was evaluated to determine the behavior of elastic and mechanical properties during the kneading and baking stage of bread. For the evaluation the following varieties were studied: Morado Brazil, Morado Ecuador, Guayaco Morado, Ina and Toquecita, and the evaluated properties were: texture (hardness, elasticity, firmness, chewiness measured by a texture meter Bloomfield and volume was measured by INEN standard (NTE INEN 0530: 80. The design employed was completely at random, using analysis of variance at 5% significance level. The results obtained showed that elasticity attribute in texture variable presented significant differences (P <0.05. Analysis concluded that including Toquecita flour in the mixture to form the dough, had the highest elasticity of 13.32mm. However, Morado Ecuador variety flour presented a 6.24 mm elasticity value, ideal for both the malleability of the dough and the freshness of the bread, and concerning volume, the inclusion of Ecuador Morado flour and Ina in the formulation of bread, showed an increase in volume at 93.30 and 93.67cm3 respectively, close to the normed value for wheat flour bread.

  10. Elements of Motivational Structure for Studying Mechanical Engineering

    OpenAIRE

    Nikša Dubreta; Damir Miloš

    2017-01-01

    The article presents the findings on students' reasons for studying mechanical engineering. These reasons were covered in terms of extrinsic and intrinsic motivation additionally related to selected independent variables of the sample – students' secondary school Grade Point Average, their gender and the socio-economic status. The research was conducted with the first year students of the Faculty of Mechanical Engineering at the University of Zagreb, Croatia. The sample consisted of 282 stude...

  11. Optimizing Usability Studies by Complementary Evaluation Methods

    NARCIS (Netherlands)

    Schmettow, Martin; Bach, Cedric; Scapin, Dominique

    2014-01-01

    This paper examines combinations of complementary evaluation methods as a strategy for efficient usability problem discovery. A data set from an earlier study is re-analyzed, involving three evaluation methods applied to two virtual environment applications. Results of a mixed-effects logistic

  12. Evaluation of Mechanical Property of Carbon Fiber/Polypropylene Composite According to Carbon Fiber Surface Treatment

    International Nuclear Information System (INIS)

    Han, Song Hee; Oh, Hyun Ju; Kim, Seong Su

    2013-01-01

    In this study, the mechanical properties of a carbon fiber/polypropylene composite were evaluated according to the carbon fiber surface treatment. Carbon fiber surface treatments such as silane coupling agents and plasma treatment were performed to enhance the interfacial strength between carbon fibers and polypropylene. The treated carbon fiber surface was characterized by XP S, Sem, and single-filament tensile test. The interlaminar shear strength (Ilks) of the composite with respect to the surface treatment was determined by a short beam shear test. The test results showed that the Ilks of the plasma-treated specimen increased with the treatment time. The Ilks of the specimen treated with a silane coupling agent after plasma treatment increased by 48.7% compared to that of the untreated specimen

  13. Fracture mechanics evaluation of feedwater line failure at Surry-2: Final report

    International Nuclear Information System (INIS)

    Zahoor, A.; Gamble, R.M.

    1987-10-01

    The purpose of this work was to perform a fracture mechanics evaluation of a failure that occurred in an elbow of the 18-inch suction line to the ''A'' main feed pump at Surry Power Station, Unit 2. The failure occurred during a pressure transient subsequent to a reactor trip, which was initiated by a low-low steam generator level protection signal. Analyses were performed to characterize the crack formation and growth sequence at the estimated failure pressure (550 psi) and normal operating pressure (367 psi); this work included predicting the longitudinal throughwall crack lengths for initial wall breakthrough and failure. A sensitivity study also was performed to assess the effect on the results of variations in several conditions that generally influence failure

  14. Fracture mechanics evaluation of feedwater line failure at Surry-2: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Zahoor, A.; Gamble, R.M.

    1987-10-01

    The purpose of this work was to perform a fracture mechanics evaluation of a failure that occurred in an elbow of the 18-inch suction line to the ''A'' main feed pump at Surry Power Station, Unit 2. The failure occurred during a pressure transient subsequent to a reactor trip, which was initiated by a low-low steam generator level protection signal. Analyses were performed to characterize the crack formation and growth sequence at the estimated failure pressure (550 psi) and normal operating pressure (367 psi); this work included predicting the longitudinal throughwall crack lengths for initial wall breakthrough and failure. A sensitivity study also was performed to assess the effect on the results of variations in several conditions that generally influence failure.

  15. A study on thermal and mechanical properties of mechanically milled HDPE and PP

    International Nuclear Information System (INIS)

    Can, S.; Tan, S.

    2003-01-01

    In this study, mechanical mixing of HDPE and PP was performed via ball milling. Prepared compositions were 75/25 , 50/50 , 25/75 w/w HDPE/PP. Milling time and ball to powder ratio (B/P) were kept constant and system was cooled by adding solid CO 2 to improve the milling efficiency. To compare these systems with traditional methods, mixtures were also melt mixed by Brabender Plasti-Corder. Both milled and melt mixed systems were examined with DSC for thermal properties and tensile testing for mechanical properties Results are discussed by comparing milled , melt mixed and as-received polymers. It is observed that, unlike ball milled systems' in melt mixed systems mechanical properties are composition dependent. In addition , ball milling results in amorphization of both polymers and very high amounts of PP (75wt %) creates very amorphous HDPE structure. (Original)

  16. Mechanism of oil-pulling therapy - in vitro study.

    Science.gov (United States)

    Asokan, Sharath; Rathinasamy, T K; Inbamani, N; Menon, Thangam; Kumar, S Senthil; Emmadi, Pamela; Raghuraman, R

    2011-01-01

    Oil pulling has been used extensively as a traditional Indian folk remedy without scientific proof for many years for strengthening teeth, gums and jaws and to prevent decay, oral malodor, bleeding gums and dryness of throat and cracked lips. The aim of this study was to evaluate the antibacterial activity of sesame oil and lignans isolated from sesame oil on oral microorganisms and to check whether saponification or emulsification occurs during oil-pulling therapy. The in vitro study was carried out in three different phases: (1) Antibacterial activity of the lignans and sesame oil were tested by minimum inhibitory concentration assay by agar dilution method and agar well diffusion method, respectively. (2) Increase in free fatty acid level of oil and the quantity of sodium hydroxide (NaOH) used up in the titration are good indicators of saponification process. This was assessed using analytical tests for vegetable oils. (3) Swished oil was observed under light microscope to assess the status of the oil, presence of microorganisms, oral debris and foreign bodies. Sesamin and sesamolin isolated from sesame oil did not have any antibacterial effect against oral microorganisms like Streptococcus mutans, Streptococcus mitis and Streptococcus viridans. Emulsification of sesame oil occurs during oil-pulling therapy. Increased consumption of NaOH in titration is a definite indication of a possible saponification process. The myth that the effect of oil-pulling therapy on oral health was just a placebo effect has been broken and there are clear indications of possible saponification and emulsification process, which enhances its mechanical cleaning action.

  17. Comparative study of some mechanical and release properties of ...

    African Journals Online (AJOL)

    The mechanical and release properties of paracetamol tablets formulated with cashew gum (CAG), povidone (PVP) and gelatin (GEL) as binders were studied and compared. The parameters studied were tensile strength (TS), brittle fracture index (BFI), friability (F), disintegration time (DT) and percentage drug released ...

  18. Effective Information Technology Governance Mechanisms: An Australian Study

    Directory of Open Access Journals (Sweden)

    Syaiful Ali

    2006-01-01

    Full Text Available Growing importance of information technology (IT, as a strategic factor for organizations in achieving their objectives, have raised the concern of organizations in establishing and implementing effective IT governance. This study seeks to empirically examine the individual IT governance mechanisms that influence the overall effectiveness of IT governance. The data were obtained by using web based survey from 176 members of ISACA (Information Systems and Audit Control Association Australia. This study examines the influences of six proposed IT governance mechanisms on the overall effectiveness of IT governance. Using Factor Analysis and Multiple Regression techniques, the current study finds significant positive relationships between the overall level of effective IT governance and the following four IT governance mechanisms: the existence of ethics/ culture of compliance in IT, corporate communication systems, an IT strategy committee, and the involvement of senior management in IT.

  19. Force decay of elastomeric chains - a mechanical design and product comparison study.

    Science.gov (United States)

    Balhoff, David A; Shuldberg, Matthew; Hagan, Joseph L; Ballard, Richard W; Armbruster, Paul C

    2011-03-01

    To evaluate the percentage force decay of elastomeric chain products utilizing three different design mechanisms simulating canine retraction; and to evaluate the percentage force decay of elastomeric chain products from four different companies. In vitro, laboratory study. LSUHSC Dental School, New Orleans, LA, USA. Closed (non-spaced), grey elastomeric chains from four companies were selected for the study. Three acrylic resin jigs were constructed to provide a framework for three simulated space closure mechanisms. The 6-5-3, the chain loop, and the 6-3 were the configuration mechanisms used in the study. An electronic force gauge was used to measure the percentage force decay associated with each elastomeric chain over 28 days at preselected times. There was a significant difference in the mean percentage force decay for the three different mechanisms (P < 0·001). For all four companies, the 6-3 mechanical design had the smallest mean percentage force decay. There was a significant difference in the mean percentage force decay for the different companies (P < 0·001). For all three mechanisms, Ormco had the smallest percentage force decay while Unitek had the highest percentage force decay. The significant difference in the mean percentage force decay for the different mechanisms suggests that the 6-3 design is a more efficient means of closing extraction spaces utilizing elastomeric chains.

  20. A Bone-Implant Interaction Mouse Model for Evaluating Molecular Mechanism of Biomaterials/Bone Interaction.

    Science.gov (United States)

    Liu, Wenlong; Dan, Xiuli; Wang, Ting; Lu, William W; Pan, Haobo

    2016-11-01

    The development of an optimal animal model that could provide fast assessments of the interaction between bone and orthopedic implants is essential for both preclinical and theoretical researches in the design of novel biomaterials. Compared with other animal models, mice have superiority in accessing the well-developed transgenic modification techniques (e.g., cell tracing, knockoff, knockin, and so on), which serve as powerful tools in studying molecular mechanisms. In this study, we introduced the establishment of a mouse model, which was specifically tailored for the assessment of bone-implant interaction in a load-bearing bone marrow microenvironment and could potentially allow the molecular mechanism study of biomaterials by using transgenic technologies. The detailed microsurgery procedures for developing a bone defect (Φ = 0.8 mm) at the metaphysis region of the mouse femur were recorded. According to our results, the osteoconductive and osseointegrative properties of a well-studied 45S5 bioactive glass were confirmed by utilizing our mouse model, verifying the reliability of this model. The feasibility and reliability of the present model were further checked by using other materials as objects of study. Furthermore, our results indicated that this animal model provided a more homogeneous tissue-implant interacting surface than the rat at the early stage of implantation and this is quite meaningful for conducting quantitative analysis. The availability of transgenic techniques to mechanism study of biomaterials was further testified by establishing our model on Nestin-GFP transgenic mice. Intriguingly, the distribution of Nestin + cells was demonstrated to be recruited to the surface of 45S5 glass as early as 3 days postsurgery, indicating that Nestin + lineage stem cells may participate in the subsequent regeneration process. In summary, the bone-implant interaction mouse model could serve as a potential candidate to evaluate the early stage tissue

  1. Functionalization of titanium with chitosan via silanation: evaluation of biological and mechanical performances.

    Directory of Open Access Journals (Sweden)

    Pauline Renoud

    Full Text Available Complications in dentistry and orthopaedic surgery are mainly induced by peri-implant bacterial infections and current implant devices do not prevent such infections. The coating of antibacterial molecules such as chitosan on its surface would give the implant bioactive properties. The major challenge of this type of coating is the attachment of chitosan to a metal substrate. In this study, we propose to investigate the functionalization of titanium with chitosan via a silanation. Firstly, the surface chemistry and mechanical properties of such coating were evaluated. We also verified if the coated chitosan retained its biocompatibility with the peri-implant cells, as well as its antibacterial properties. FTIR and Tof-SIMS analyses confirmed the presence of chitosan on the titanium surface. This coating showed great scratch resistance and was strongly adhesive to the substrate. These mechanical properties were consistent with an implantology application. The Chitosan-coated surfaces showed strong inhibition of Actinomyces naeslundii growth; they nonetheless showed a non significant inhibition against Porphyromonas gingivalis after 32 hours in liquid media. The chitosan-coating also demonstrated good biocompatibility to NIH3T3 fibroblasts. Thus this method of covalent coating provides a biocompatible material with improved bioactive properties. These results proved that covalent coating of chitosan has significant potential in biomedical device implantation.

  2. Evaluation of the Antibacterial Effects and Mechanism of Action of Protocatechualdehyde against Ralstonia solanacearum

    Directory of Open Access Journals (Sweden)

    Shili Li

    2016-06-01

    Full Text Available Protocatechualdehyde (PCA is an important plant-derived natural product that has been associated with a wide variety of biological activities and has been widely used in medicine as an antioxidant, anti-aging and an anti-inflammatory agent. However, fewer reports concerning its antibacterial effects on plant-pathogenic bacteria exist. Therefore, in this study, protocatechualdehyde was evaluated for its antibacterial activity against plant pathogens along with the mechanism of its antibacterial action. PCA at 40 μg/mL was highly active against R. solanacearum and significantly inhibited its growth. The minimum bactericidal concentration and minimum inhibitory concentration values for PCA were 40 μg/mL and 20 μg/mL, respectively. Further investigation of the mechanism of action of PCA via transmission electron microscopy and biological assays indicated that the destruction of the cell structure, the shapes and the inhibition of biofilm formation were important. In addition, the application of PCA effectively reduced the incidence of bacterial wilt on tobacco under greenhouse conditions, and the control efficiency was as high as 92.01% at nine days after inoculation. Taken together, these findings suggest that PCA exhibits strong antibacterial activity against R. solanacearum and has the potential to be applied as an effective antibacterial agent for controlling bacterial wilt caused by R. solanacearum.

  3. Evaluation of the mechanism of skin enhancing surfactants on the biomembrane of shed snake skin.

    Science.gov (United States)

    Wonglertnirant, Nanthida; Ngawhirunpat, Tanasait; Kumpugdee-Vollrath, Mont

    2012-01-01

    The aim of the present work was to investigate the effects of different surfactants at various concentrations as a skin penetration enhancer through the biomembrane of the shed skin of Naja kaouthia. Additionally, the enhancer mechanism(s) of each class of surfactants were evaluated using physical characterization techniques, such as scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, and small and wide angle X-ray scattering (SWAXS). Our results showed that skin permeability increased with increasing concentrations of surfactants and the degree of increase was higher for the model hydrophilic permeant, deuterium dioxide (D(2)O), than the lipophilic permeant, ketoprofen (KP). Ionic surfactants, sodium lauryl sulfate (SLS) and cetyl trimethyl ammonium bromide (CTAB), demonstrated higher enhancement ability than the polyoxyethylene (20) sorbitan mono-oleate (Tween 80) non-ionic surfactant, which was consistent with the results from physical characterization studies. Increasing amounts of permeated drug resulted in an increase in membrane interactions. From our observations, it can be assumed that SLS and CTAB can be localized inside the biomembrane and thereby enhance drug permeation mainly through interactions with intercellular lipids in the stratum corneum (SC) and the creation of a perturbed microenvironment among lipid alkyl chains and polar head groups.

  4. Developing, Evaluating and Demonstrating the Use of a Conceptual Survey in Mechanical Waves

    Science.gov (United States)

    Tongchai, Apisit; Sharma, Manjula D.; Johnston, Ian D.; Arayathanitkul, Kwan; Soankwan, Chernchok

    2009-01-01

    An understanding of mechanical waves is a pre-requisite for the study of many topics in advanced physics, and indeed in many other disciplines. There have been many research studies in mechanical waves, all of which have revealed that students have trouble with the basic concepts. Therefore, in order for teachers to prepare appropriate instruction…

  5. NEMD study for supercavitation mechanism with underwater object

    Energy Technology Data Exchange (ETDEWEB)

    Gong Bozhi [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Zhang Bingjian [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China)], E-mail: zbj@mail.ha.zj.cn; Zhang Hui [Department of Chemistry, Ohio State University, Columbus, OH 43210 (United States)

    2008-11-24

    An open system model was introduced for Non-Equilibrium Molecular Dynamics (NEMD) simulation for studying flow phenomenon surrounding different underwater object. Cavitation number {sigma} criterion was proved to be applicable in predicting local cavitation mechanism. An interesting phenomenon was found that low {sigma} areas and actual cavities were spatially separated in molecular scale, and stable supercavitation would require a large enough low {sigma} area to sustain. Effects of cavitator shape and flow velocity were compared with macro scale flow under similar {sigma}, providing a new computational method to study the molecular scale mechanism of this phenomenon.

  6. NEMD study for supercavitation mechanism with underwater object

    International Nuclear Information System (INIS)

    Gong Bozhi; Zhang Bingjian; Zhang Hui

    2008-01-01

    An open system model was introduced for Non-Equilibrium Molecular Dynamics (NEMD) simulation for studying flow phenomenon surrounding different underwater object. Cavitation number σ criterion was proved to be applicable in predicting local cavitation mechanism. An interesting phenomenon was found that low σ areas and actual cavities were spatially separated in molecular scale, and stable supercavitation would require a large enough low σ area to sustain. Effects of cavitator shape and flow velocity were compared with macro scale flow under similar σ, providing a new computational method to study the molecular scale mechanism of this phenomenon

  7. Study on Excitation-triggered Damage Mechanism in Perilous Rock

    Science.gov (United States)

    Chen, Hongkai; Wang, Shengjuan

    2017-12-01

    Chain collapse is easy to happen for perilous rock aggregate locating on steep high slope, and one of the key scientific problems is the damage mechanism of perilous rock under excitation action at perilous rock rupture. This paper studies excitation-triggered damage mechanism in perilous rock by wave mechanics, which gives three conclusions. Firstly, when only the normal incidence attenuation spread of excitation wave is considered, while the energy loss is ignored for excitation wave to spread in perilous rock aggregate, the paper establishes one method to calculate peak velocity when excitation wave passes through boundary between any two perilous rock blocks in perilous rock aggregate. Secondly, following by Sweden and Canmet criteria, the paper provides one wave velocity criterion for excitation-triggered damage in the aggregate. Thirdly, assuming double parameters of volume strain of cracks or fissures in rock meet the Weibull distribution, one method to estimate micro-fissure in excitation-triggered damage zone in perilous rock aggregate is established. The studies solve the mechanical description problem for excitation-triggered damage in perilous rock, which is valuable in studies on profoundly rupture mechanism.

  8. Economic Evaluation of a Patient-Directed Music Intervention for ICU Patients Receiving Mechanical Ventilatory Support.

    Science.gov (United States)

    Chlan, Linda L; Heiderscheit, Annette; Skaar, Debra J; Neidecker, Marjorie V

    2018-05-04

    Music intervention has been shown to reduce anxiety and sedative exposure among mechanically ventilated patients. Whether music intervention reduces ICU costs is not known. The aim of this study was to examine ICU costs for patients receiving a patient-directed music intervention compared with patients who received usual ICU care. A cost-effectiveness analysis from the hospital perspective was conducted to determine if patient-directed music intervention was cost-effective in improving patient-reported anxiety. Cost savings were also evaluated. One-way and probabilistic sensitivity analyses determined the influence of input variation on the cost-effectiveness. Midwestern ICUs. Adult ICU patients from a parent clinical trial receiving mechanical ventilatory support. Patients receiving the experimental patient-directed music intervention received a MP3 player, noise-canceling headphones, and music tailored to individual preferences by a music therapist. The base case cost-effectiveness analysis estimated patient-directed music intervention reduced anxiety by 19 points on the Visual Analogue Scale-Anxiety with a reduction in cost of $2,322/patient compared with usual ICU care, resulting in patient-directed music dominance. The probabilistic cost-effectiveness analysis found that average patient-directed music intervention costs were $2,155 less than usual ICU care and projected that cost saving is achieved in 70% of 1,000 iterations. Based on break-even analyses, cost saving is achieved if the per-patient cost of patient-directed music intervention remains below $2,651, a value eight times the base case of $329. Patient-directed music intervention is cost-effective for reducing anxiety in mechanically ventilated ICU patients.

  9. Oxidation and metal-insertion in molybdenite surfaces: evaluation of charge-transfer mechanisms and dynamics

    Directory of Open Access Journals (Sweden)

    Shutthanandan V

    2008-06-01

    Full Text Available Abstract Molybdenum disulfide (MoS2, a layered transition-metal dichalcogenide, has been of special importance to the research community of geochemistry, materials and environmental chemistry, and geotechnical engineering. Understanding the oxidation behavior and charge-transfer mechanisms in MoS2 is important to gain better insight into the degradation of this mineral in the environment. In addition, understanding the insertion of metals into molybdenite and evaluation of charge-transfer mechanism and dynamics is important to utilize these minerals in technological applications. Furthermore, a detailed investigation of thermal oxidation behavior and metal-insertion will provide a basis to further explore and model the mechanism of adsorption of metal ions onto geomedia. The present work was performed to understand thermal oxidation and metal-insertion processes of molybdenite surfaces. The analysis was performed using atomic force microscopy (AFM, scanning electron microscopy (SEM, transmission electron microscopy (TEM, Rutherford backscattering spectrometry (RBS, and nuclear reaction analysis (NRA. Structural studies using SEM and TEM indicate the local-disordering of the structure as a result of charge-transfer process between the inserted lithium and the molybdenite layer. Selected area electron diffraction measurements indicate the large variations in the diffusivity of lithium confirming that the charge-transfer is different along and perpendicular to the layers in molybdenite. Thermal heating of molybenite surface in air at 400°C induces surface oxidation, which is slow during the first hour of heating and then increases significantly. The SEM results indicate that the crystals formed on the molybdenite surface as a result of thermal oxidation exhibit regular thin-elongated shape. The average size and density of the crystals on the surface is dependent on the time of annealing; smaller size and high density during the first one-hour and

  10. Oxidation and metal-insertion in molybdenite surfaces: evaluation of charge-transfer mechanisms and dynamics.

    Science.gov (United States)

    Ramana, C V; Becker, U; Shutthanandan, V; Julien, C M

    2008-06-05

    Molybdenum disulfide (MoS2), a layered transition-metal dichalcogenide, has been of special importance to the research community of geochemistry, materials and environmental chemistry, and geotechnical engineering. Understanding the oxidation behavior and charge-transfer mechanisms in MoS2 is important to gain better insight into the degradation of this mineral in the environment. In addition, understanding the insertion of metals into molybdenite and evaluation of charge-transfer mechanism and dynamics is important to utilize these minerals in technological applications. Furthermore, a detailed investigation of thermal oxidation behavior and metal-insertion will provide a basis to further explore and model the mechanism of adsorption of metal ions onto geomedia.The present work was performed to understand thermal oxidation and metal-insertion processes of molybdenite surfaces. The analysis was performed using atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Rutherford backscattering spectrometry (RBS), and nuclear reaction analysis (NRA).Structural studies using SEM and TEM indicate the local-disordering of the structure as a result of charge-transfer process between the inserted lithium and the molybdenite layer. Selected area electron diffraction measurements indicate the large variations in the diffusivity of lithium confirming that the charge-transfer is different along and perpendicular to the layers in molybdenite. Thermal heating of molybenite surface in air at 400 degrees C induces surface oxidation, which is slow during the first hour of heating and then increases significantly. The SEM results indicate that the crystals formed on the molybdenite surface as a result of thermal oxidation exhibit regular thin-elongated shape. The average size and density of the crystals on the surface is dependent on the time of annealing; smaller size and high density during the first one-hour and significant

  11. An experimental study on damping characteristics of mechanical snubber for nuclear power plant piping systems

    International Nuclear Information System (INIS)

    Chiba, T.; Kobayashi, H.; Kitamura, K.; Ando, K.; Koyanagi, R.

    1983-01-01

    The objectives of this study are 1) to clarify the damping characteristics and the dynamic stiffness of mechanical snubber, 2) to take the damping characteristics of mechanical snubber into the damping evaluation method obtained in SDREP. Therefore, following vibration tests were conducted. 1) Component test: As a first step, mechanical snubbers were excited with sinusoidal wave, and damping ratio and dynamic stiffness were measured at several loading levels. 2) Piping model test: Second, a 8'' diameter x 16 m length 3-dimensional piping model simulating the supporting conditions of actual piping systems was tested. Damping ratio and made shapes of piping model with mechanical snubbers were measured at several supporting conditions and response levels. From the results of these tests, the damping characteristics and the dynamic stiffness of mechanical snubber can be summarized as follows: 1) The damping effect of mechanical snubber is as strong as that of oil snubber. 2) Mechanical snubber contributes effectively to the damping of piping system, and it is indicated that the damping characteristics of mechanical snubber is applicable to the damping evaluation method obtained in SDREP. (orig./HP)

  12. Creating Evaluation Profiles for Games Designed to be Fun: An Interpretive Framework for Serious Game Mechanics

    DEFF Research Database (Denmark)

    Ulrich, Frank; Helms, Niels Henrik

    2017-01-01

    an interpretive evaluation framework that can identify the educational value in COTS games. Application. The presented framework can create evaluative profiles of the learning, social, game, and immersive mechanics of COTS games as educational tools. Moreover, the framework can position COTS games between four...... intertwined dimensions, namely pedagogical, design, knowledge, and sociotechnical considerations. Demonstration. To validate the practical application of the interpretive framework, we apply it to a real-world example. Our demonstration reveals the usefulness of the framework. Conclusions. The framework...

  13. Evaluation of mechanical properties of steel wire ropes by statistical methods

    Directory of Open Access Journals (Sweden)

    Boroška Ján

    1999-12-01

    Full Text Available The contribution deals with the evaluation of mechanical properties of steel wire ropes using statistical methods from the viewpoint of the quality of single wires as well as the internal construction of the wire ropes. The evaluation is based on the loading capacity calculated from the strength, number of folds and torsions. For the better ilustration, a box plot has been constructed.

  14. Mechanical reliability evaluation of alternate motors for use in a radioiodine air sampler

    International Nuclear Information System (INIS)

    Bird, S.K.; Huchton, R.L.; Motes, B.G.

    1984-03-01

    Detailed mechanical reliability studies of two alternate motors identified for use in the BNL Air Sampler wer conducted. The two motor types were obtained from Minnesota Electric Technology, Incorporated (MET) and TCS Industries (TCSI). Planned testing included evaluation of motor lifetimes and motor operability under different conditions of temperature, relative humidity, simulated rainfall, and dusty air. The TCSI motors were not lifetime tested due to their poor performance during the temperature/relative humidity tests. While operation on alternating current was satisfactory, on direct current only one of five TCSI motors completed all environmental testing. The MET motors had average lifetimes of 47 hours, 97 hours, and 188 hours, respectively, and exhibited satisfactory operation under all environmental test conditions. Therefore, the MET motor appears to be the better candidate motor for use in the BNL Air Sampler. However, because of the relatively high cost of purchasing and incorporating the MET motor into the BNL Air Sampler System, it is recommended that commercial air sampler systems be evaluated for use instead of the BNL system

  15. In Vitro Evaluation and Mechanism Analysis of the Fiber Shedding Property of Textile Pile Debridement Materials

    Directory of Open Access Journals (Sweden)

    Yijun Fu

    2016-04-01

    Full Text Available Fiber shedding is a critical problem in biomedical textile debridement materials, which leads to infection and impairs wound healing. In this work, single fiber pull-out test was proposed as an in vitro evaluation for the fiber shedding property of a textile pile debridement material. Samples with different structural design (pile densities, numbers of ground yarns and coating times were prepared and estimated under this testing method. Results show that single fiber pull-out test offers an appropriate in vitro evaluation for the fiber shedding property of textile pile debridement materials. Pull-out force for samples without back-coating exhibited a slight escalating trend with the supplement in pile density and number of ground yarn plies, while back-coating process significantly raised the single fiber pull-out force. For fiber shedding mechanism analysis, typical pull-out behavior and failure modes of the single fiber pull-out test were analyzed in detail. Three failure modes were found in this study, i.e., fiber slippage, coating point rupture and fiber breakage. In summary, to obtain samples with desirable fiber shedding property, fabric structural design, preparation process and raw materials selection should be taken into full consideration.

  16. Mechanism analysis and evaluation methodology of regenerative braking contribution to energy efficiency improvement of electrified vehicles

    International Nuclear Information System (INIS)

    Lv, Chen; Zhang, Junzhi; Li, Yutong; Yuan, Ye

    2015-01-01

    Highlights: • The energy flow of an electric vehicle with regenerative brake is analyzed. • Methodology for measuring the regen brake contribution is discussed. • Evaluation parameters of regen brake contribution are proposed. • Vehicle tests are carried out on chassis dynamometer. • Test results verify the evaluation method and parameters proposed. - Abstract: This article discusses the mechanism and evaluation methods of contribution brought by regenerative braking to electric vehicle’s energy efficiency improvement. The energy flow of an electric vehicle considering the braking energy regeneration was analyzed. Then, methodologies for measuring the contribution made by regenerative brake to vehicle energy efficiency improvement were introduced. Based on the energy flow analyzed, two different evaluation parameters were proposed. Vehicle tests were carried out on chassis dynamometer under typical driving cycles with three different control strategies. The experimental results the difference between the proposed two evaluation parameters, and demonstrated the feasibility and effectiveness of the evaluation methodologies proposed

  17. Hand function evaluation: a factor analysis study.

    Science.gov (United States)

    Jarus, T; Poremba, R

    1993-05-01

    The purpose of this study was to investigate hand function evaluations. Factor analysis with varimax rotation was used to assess the fundamental characteristics of the items included in the Jebsen Hand Function Test and the Smith Hand Function Evaluation. The study sample consisted of 144 subjects without disabilities and 22 subjects with Colles fracture. Results suggest a four factor solution: Factor I--pinch movement; Factor II--grasp; Factor III--target accuracy; and Factor IV--activities of daily living. These categories differentiated the subjects without Colles fracture from the subjects with Colles fracture. A hand function evaluation consisting of these four factors would be useful. Such an evaluation that can be used for current clinical purposes is provided.

  18. Design and Evaluation of an Electronic Override Mechanism for Medication Alerts to Facilitate Communication Between Prescribers and Pharmacists.

    Science.gov (United States)

    Russ, Alissa L; Chen, Siying; Melton, Brittany L; Saleem, Jason J; Weiner, Michael; Spina, Jeffrey R; Daggy, Joanne K; Zillich, Alan J

    2015-07-01

    Computerized medication alerts can often be bypassed by entering an override rationale, but prescribers' override reasons are frequently ambiguous to pharmacists who review orders. To develop and evaluate a new override mechanism for adverse reaction and drug-drug interaction alerts. We hypothesized that the new mechanism would improve usability for prescribers and increase the clinical appropriateness of override reasons. A counterbalanced, crossover study was conducted with 20 prescribers in a simulated prescribing environment. We modified the override mechanism timing, navigation, and text entry. Instead of free-text entry, the new mechanism presented prescribers with a predefined set of override reasons. We assessed usability (learnability, perceived efficiency, and usability errors) and used a priori criteria to evaluate the clinical appropriateness of override reasons entered. Prescribers rated the new mechanism as more efficient (Wilcoxon signed-rank test, P = 0.032). When first using the new design, 5 prescribers had difficulty finding the new mechanism, and 3 interpreted the navigation to mean that the alert could not be overridden. The number of appropriate override reasons significantly increased with the new mechanism compared with the original mechanism (median change of 3.0; interquartile range = 3.0; P < 0.0001). When prescribers were given a menu-based choice for override reasons, clinical appropriateness of these reasons significantly improved. Further enhancements are necessary, but this study is an important first step toward a more standardized menu of override choices. Findings may be used to improve communication through e-prescribing systems between prescribers and pharmacists. © The Author(s) 2015.

  19. The Mechanical Axis of the First Ray: A Radiographic Assessment in Hallux Abducto Valgus Evaluation.

    Science.gov (United States)

    LaPorta, Guido A; Nasser, Ellianne M; Mulhern, Jennifer L; Malay, D Scot

    2016-01-01

    The present report describes a new method of hallux abducto valgus deformity correction planning using the mechanical axis of the medial column (mechanical axis planning). This method of radiographic evaluation identifies an ideal position for the first metatarsal after correction and is useful regardless of the surgical procedure chosen. We retrospectively reviewed 200 radiographs to identify a "normal" value for the mechanical axis angle. We reviewed 100 radiographs of patients with hallux abducto valgus deformity (deformity group) and 100 radiographs of patients without hallux abducto valgus deformity (control group). The deformity group revealed an M1-M2 anatomic axis angle of 13.5° ± 2.83° and an M1-M2 mechanical axis angle of 11.58° ± 1°. The control group revealed an M1-M2 anatomic axis angle of 7.5° ± 1.76° and an M1-M2 mechanical axis angle of 11.19° ± 0.9°. The differences in the M1-M2 anatomic axis angle and M1-M2 mechanical axis angle were statistically significant between the control and deformity groups. We sought to provide a reliable method for planning hallux abducto valgus deformity correction by aligning the mechanical axis of the medial column and the mechanical axis of the first ray to the "normal" value of 11° to reduce the deformity. Copyright © 2016 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  20. Elements of Motivational Structure for Studying Mechanical Engineering

    Science.gov (United States)

    Dubreta, Nikša; Miloš, Damir

    2017-01-01

    The article presents the findings on students' reasons for studying mechanical engineering. These reasons were covered in terms of extrinsic and intrinsic motivation additionally related to selected independent variables of the sample--students' secondary school Grade Point Average, their gender and the socio-economic status. The research was…

  1. Mechanical Study of a Modern Yo-Yo

    Science.gov (United States)

    de Izarra, Charles

    2011-01-01

    This paper presents the study of a modern yo-yo having a centrifugal clutch allowing the free rolling. First, the mechanical parts of the yo-yo are measured, allowing us to determine analytically its velocity according to its height of fall. Then, we are more particularly interested in the centrifugal device constituted by springs and small…

  2. Organizational evaluation of an interprofessional study unit

    DEFF Research Database (Denmark)

    Jensen, Didde Cramer; Nørgaard, Birgitte; Draborg, Eva

    2012-01-01

    This article presents results from an organizational evaluation of an interprofessional clinical study unit (ICS) in Denmark. The aim of this study was to test whether the ICS was based on a durable organizational concept and to identify the prerequisites for the unit to be successful...

  3. PHYSIOTHERAPY FOR CLUMSY CHILDREN - AN EVALUATION STUDY

    NARCIS (Netherlands)

    SCHOEMAKER, MM; HIJLKEMA, MGJ; KALVERBOER, AF

    This study reports the findings of an effect-evaluation study of physiotherapy for clumsy children. 18 children were identified by school doctors as having poor motor co-ordination. They were followed for three months in order to exclude spontaneous improvement of motor problems; none spontaneously

  4. The Evaluation of Higher Education Expenditure Performance and Investment Mechanism Reform

    Science.gov (United States)

    Wang, De; Fu, Meiying

    2009-01-01

    Along with the reform of Chinese Government public finance, higher education belongs to the public product, gradually changes from "fund investment management" to the "expenditure performance management". The evaluation of expenditure performance system becomes the key point of higher education investment mechanism reform. This…

  5. Computation and Communication Evaluation of an Authentication Mechanism for Time-Triggered Networked Control Systems

    Science.gov (United States)

    Martins, Goncalo; Moondra, Arul; Dubey, Abhishek; Bhattacharjee, Anirban; Koutsoukos, Xenofon D.

    2016-01-01

    In modern networked control applications, confidentiality and integrity are important features to address in order to prevent against attacks. Moreover, network control systems are a fundamental part of the communication components of current cyber-physical systems (e.g., automotive communications). Many networked control systems employ Time-Triggered (TT) architectures that provide mechanisms enabling the exchange of precise and synchronous messages. TT systems have computation and communication constraints, and with the aim to enable secure communications in the network, it is important to evaluate the computational and communication overhead of implementing secure communication mechanisms. This paper presents a comprehensive analysis and evaluation of the effects of adding a Hash-based Message Authentication (HMAC) to TT networked control systems. The contributions of the paper include (1) the analysis and experimental validation of the communication overhead, as well as a scalability analysis that utilizes the experimental result for both wired and wireless platforms and (2) an experimental evaluation of the computational overhead of HMAC based on a kernel-level Linux implementation. An automotive application is used as an example, and the results show that it is feasible to implement a secure communication mechanism without interfering with the existing automotive controller execution times. The methods and results of the paper can be used for evaluating the performance impact of security mechanisms and, thus, for the design of secure wired and wireless TT networked control systems. PMID:27463718

  6. Evaluation of autophagy as a mechanism involved in air pollutant-induced pulmonary injury

    Science.gov (United States)

    Evaluation of autophagy as a mechanism involved in air pollutant-induced pulmonary injuryHenriquez, A.1, Snow, S.2, Miller, D1.,Schladweiler, M.2 and Kodavanti, U2.1 Curriculum in Toxicology, UNC, Chapel Hill, NC. 2 EPHD/NHEERL, US EPA, RTP, Durham, NC. ...

  7. Scope of work for evaluating the mechanical performance of EPR first wall coatings

    International Nuclear Information System (INIS)

    Jones, W.B.; Van Den Avyle, J.A.

    1978-01-01

    An outline is presented for a proposed scope of work to evaluate the mechanical performance of candidate first wall coatings for a Tokamak-type fusion reactor. The goal of the overall program is to provide an adequate coating material and recoating process which can be manufactured by currently available vendors

  8. Immuno-pharmacodynamics for evaluating mechanism of action and developing immunotherapy combinations.

    Science.gov (United States)

    Parchment, Ralph E; Voth, Andrea Regier; Doroshow, James H; Berzofsky, Jay A

    2016-08-01

    Immunotherapy has become a major modality of cancer treatment, with multiple new classes of immunotherapeutics recently entering the clinic and obtaining market approval from regulatory agencies. While the promise of these therapies is great, so is the number of possible combinations not only with each other but also with small molecule therapeutics. Furthermore, the observation of unusual dose-response relationships suggests a critical dependency of drug effectiveness on the dosage regimen (dose and schedule). Clinical pharmacodynamic (PD) biomarkers will be useful endpoints for confirming drug mechanism of action, evaluating combination therapies for synergy or antagonism, and identifying optimal dosage regimens. In contrast to conventional PD in which drug action occurs entirely within a single target cell (ie, is self-contained within the malignant cell), immunotherapy involves a complex mechanism of action with sequential steps that propagate through multiple cell types, both normal and malignant. Its intercellular pharmacology begins with molecular target engagement either on an immune effector cell or a malignant cell, followed by stimulatory biochemical and biological signals in immune effector cells, and then finally ends with activation of cell death mechanisms in malignant cells lying within a certain distance from the activated effector cells (immune cell-tumor cell proximity). Evaluating such "trans-cellular pharmacology," in which different steps of drug action are distributed across multiple cell types, requires novel microscopy and image analysis tools capable of quantifying PD-biomarker responses, mapping the responses onto the cellular geography of the tumor using phenotypic biomarkers to identify specific cell types, and finally analyzing the spatial relationships between biomarkers in the context of each cell's biological role. We have termed this form of nearest neighbor image analysis of drug action "proximity PD microscopy," to indicate the

  9. Diagnostics for studies of novel laser ion acceleration mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Senje, Lovisa; Aurand, Bastian; Wahlström, Claes-Göran [Department of Physics, Lund University, P. O. Box 118, S-221 00 Lund (Sweden); Yeung, Mark; Kuschel, Stephan; Rödel, Christian [Helmholtz-Institut Jena, D-07743 Jena (Germany); Wagner, Florian; Roth, Markus [Technische Universität Darmstadt, D-64289 Darmstadt (Germany); Li, Kun; Neumayer, Paul [ExtreMe Matter Institut, D-64291 Darmstadt (Germany); Dromey, Brendan; Jung, Daniel [Department of Physics and Astronomy, Queen' s University, Belfast BT7 1NN (United Kingdom); Bagnoud, Vincent [Helmholtz-Institut Jena, D-07743 Jena (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Zepf, Matthew [Helmholtz-Institut Jena, D-07743 Jena (Germany); Department of Physics and Astronomy, Queen' s University, Belfast BT7 1NN (United Kingdom); Kuehl, Thomas [ExtreMe Matter Institut, D-64291 Darmstadt (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Universität Mainz, D-55099 Mainz (Germany)

    2014-11-15

    Diagnostic for investigating and distinguishing different laser ion acceleration mechanisms has been developed and successfully tested. An ion separation wide angle spectrometer can simultaneously investigate three important aspects of the laser plasma interaction: (1) acquire angularly resolved energy spectra for two ion species, (2) obtain ion energy spectra for multiple species, separated according to their charge to mass ratio, along selected axes, and (3) collect laser radiation reflected from and transmitted through the target and propagating in the same direction as the ion beam. Thus, the presented diagnostic constitutes a highly adaptable tool for accurately studying novel acceleration mechanisms in terms of their angular energy distribution, conversion efficiency, and plasma density evolution.

  10. Diagnostics for studies of novel laser ion acceleration mechanisms

    International Nuclear Information System (INIS)

    Senje, Lovisa; Aurand, Bastian; Wahlström, Claes-Göran; Yeung, Mark; Kuschel, Stephan; Rödel, Christian; Wagner, Florian; Roth, Markus; Li, Kun; Neumayer, Paul; Dromey, Brendan; Jung, Daniel; Bagnoud, Vincent; Zepf, Matthew; Kuehl, Thomas

    2014-01-01

    Diagnostic for investigating and distinguishing different laser ion acceleration mechanisms has been developed and successfully tested. An ion separation wide angle spectrometer can simultaneously investigate three important aspects of the laser plasma interaction: (1) acquire angularly resolved energy spectra for two ion species, (2) obtain ion energy spectra for multiple species, separated according to their charge to mass ratio, along selected axes, and (3) collect laser radiation reflected from and transmitted through the target and propagating in the same direction as the ion beam. Thus, the presented diagnostic constitutes a highly adaptable tool for accurately studying novel acceleration mechanisms in terms of their angular energy distribution, conversion efficiency, and plasma density evolution

  11. Mechanisms of CFR composites destruction studying with pulse acoustic microscopy

    Science.gov (United States)

    Petronyuk, Y. S.; Morokov, E. S.; Levin, V. M.; Ryzhova, T. B.; Chernov, A. V.

    2016-05-01

    Non-destructive inspection of carbon-fiber-reinforced (CFR) composites applied in aerospace industry attracts a wide attention. In the paper, high frequency focused ultrasound (50-100 MHz) has been applied to study the bulk microstructure of the CFR material and mechanisms of its destruction under the mechanical loading. It has been shown impulse acoustic microscopy provides detecting the areas of adhesion loss at millimeter and micron level. Behavior of the CFR laminate structure fabricated by prepreg or infusion technology has been investigated under the tensile and impact loading.

  12. Creating Evaluation Profiles for Games Designed to be Fun: An Interpretive Framework for Serious Game Mechanics

    DEFF Research Database (Denmark)

    Ulrich, Frank; Helms, Niels Henrik

    2017-01-01

    Background. Games can be great pedagogical tools for educators and students. COTS games (commercialoff-the-shelf) are designed for the pure purpose of leisure but can also contain educational value. Aim. In this paper, we address the potential of COTS games as serious games. We develop...... an interpretive evaluation framework that can identify the educational value in COTS games. Application. The presented framework can create evaluative profiles of the learning, social, game, and immersive mechanics of COTS games as educational tools. Moreover, the framework can position COTS games between four...... enables critical reflection on the game mechanics; thereby capturing the complexity of the game mechanics that makes COTS game both educational and fun to play....

  13. Quantum Mechanics and Molecular Mechanics Study of the Catalytic Mechanism of Human AMSH-LP Domain Deubiquitinating Enzymes.

    Science.gov (United States)

    Zhu, Wenyou; Liu, Yongjun; Ling, Baoping

    2015-08-25

    Deubiquitinating enzymes (DUBs) catalyze the cleavage of the isopeptide bond in polyubiquitin chains to control and regulate the deubiquitination process in all known eukaryotic cells. The human AMSH-LP DUB domain specifically cleaves the isopeptide bonds in the Lys63-linked polyubiquitin chains. In this article, the catalytic mechanism of AMSH-LP has been studied using a combined quantum mechanics and molecular mechanics method. Two possible hydrolysis processes (Path 1 and Path 2) have been considered. Our calculation results reveal that the activation of Zn(2+)-coordinated water molecule is the essential step for the hydrolysis of isopeptide bond. In Path 1, the generated hydroxyl first attacks the carbonyl group of Gly76, and then the amino group of Lys63 is protonated, which is calculated to be the rate limiting step with an energy barrier of 13.1 kcal/mol. The energy barrier of the rate limiting step and the structures of intermediate and product are in agreement with the experimental results. In Path 2, the protonation of amino group of Lys63 is prior to the nucleophilic attack of activated hydroxyl. The two proton transfer processes in Path 2 correspond to comparable overall barriers (33.4 and 36.1 kcal/mol), which are very high for an enzymatic reaction. Thus, Path 2 can be ruled out. During the reaction, Glu292 acts as a proton transfer mediator, and Ser357 mainly plays a role in stabilizing the negative charge of Gly76. Besides acting as a Lewis acid, Zn(2+) also influences the reaction by coordinating to the reaction substrates (W1 and Gly76).

  14. Evaluation of the effect and mechanism of action of local phenytoin in treatment of vitiligo.

    Science.gov (United States)

    Abdou, Asmaa Gaber; Abdelwahed Gaber, Mohammed; Elnaidany, Nada Farag; Elnagar, Ayat

    2017-01-01

    There are many theories explaining vitiligo such as genetic, autoimmune, neural, free radicals, biochemical, intrinsic defect, melanocytorrhagy, and convergent theories. Phenytoin is a widely used anticonvulsant, which is used in cutaneous medicine for treatment of ulcers and epidermolysis bullosa. The aim of this study is to assess the effectiveness of topical phenytoin gel in the treatment of vitiligo patients and explaining the underlying mechanism using immunohistochemistry for evaluation of HMB45, CD4, and CD8. Only 9 patients out of 28 experienced response to phenytoin in the form of dull, white color change and light brown color. Post-phenytoin treatment biopsies showed decreased density of inflammation, increased melanin and increased HMB45 positive cells together with an increased number of CD4 positive lymphocytes and decreased number of CD8 positive lymphocytes. These observations did not reach significant level (P > 0.05). A high percentage of CD4 positive lymphocytes was significantly associated with a long duration of vitiligo (p = 0.03) and segmental vitiligo type (p = 0.02). The current study applied phenytoin as 2% concentrated gel for 3 months, which is a relatively short duration without observed side effects throughout the period. These results indicate that topical phenytoin of low concentrations may have beneficial effects through immunomodulatory activity by affecting CD4 and CD8 counts and subsequently the ratio between them. Further studies are recommended to combine phenytoin with other antivitiligo agents as local corticosteroids or phototherapy to clarify if it could potentiate their effects.

  15. [Studies on the mechanical properties of the knee ligament].

    Science.gov (United States)

    Kubotera, D

    1987-04-01

    To study mechanical properties of the knee ligaments, tension tests at various speeds were performed on the knee of a dog with only the collateral ligament. The results showed that the tensile force was greater in high speed than in low speed test. The difference may be caused in a viscous property of the ligament. The mechanical properties of ligaments can therefore be treated as those of viscoelastic materials and expressed by a modified Voigt model consisting of a non-linear spring element and a dash pot component. Observations regarding the ultrastructure of human knee ligaments using an electron scanning microscope revealed wavy bundles of collagen fiber connected with coarse fibers like network running in parallel with the long axis as the main structure. The above structure and properties were considered to be the decisive factors in the mechanical actions of the knee ligament.

  16. Dose-dependent transitions in mechanisms of toxicity: case studies

    International Nuclear Information System (INIS)

    Slikker, William; Andersen, Melvin E.; Bogdanffy, Matthew S.; Bus, James S.; Cohen, Steven D.; Conolly, Rory B.; David, Raymond M.; Doerrer, Nancy G.; Dorman, David C.; Gaylor, David W.; Hattis, Dale; Rogers, John M.; Setzer, R. Woodrow; Swenberg, James A.; Wallace, Kendall

    2004-01-01

    Experience with dose response and mechanisms of toxicity has shown that multiple mechanisms may exist for a single agent along the continuum of the full dose-response curve. It is highly likely that critical, limiting steps in any given mechanistic pathway may become overwhelmed with increasing exposures, signaling the emergence of new modalities of toxic tissue injury at these higher doses. Therefore, dose-dependent transitions in principal mechanisms of toxicity may occur, and could have significant impact on the interpretation of reference data sets for risk assessment. To illustrate the existence of dose-dependent transitions in mechanisms of toxicity, a group of academic, government, and industry scientists, formed under the leadership of the ILSI Health and Environmental Sciences Institute (HESI), developed a series of case studies. These case studies included acetaminophen, butadiene, ethylene glycol, formaldehyde, manganese, methylene chloride, peroxisome proliferator-activated receptor (PPAR), progesterone/hydroxyflutamide, propylene oxide, vinyl acetate, vinyl chloride, vinylidene chloride, and zinc. The case studies formed the basis for technical discourse at two scientific workshops in 2003

  17. Study of Profile Changes during Mechanical Polishing using Relocation Profilometry

    Science.gov (United States)

    Kumaran, S. Chidambara; Shunmugam, M. S.

    2017-10-01

    Mechanical polishing is a finishing process practiced conventionally to enhance quality of surface. Surface finish is improved by mechanical cutting action of abrasive particles on work surface. Polishing is complex in nature and research efforts have been focused on understanding the polishing mechanism. Study of changes in profile is a useful method of understanding behavior of the polishing process. Such a study requires tracing same profile at regular process intervals, which is a tedious job. An innovative relocation technique is followed in the present work to study profile changes during mechanical polishing of austenitic stainless steel specimen. Using special locating fixture, micro-indentation mark and cross-correlation technique, the same profile is traced at certain process intervals. Comparison of different parameters of profiles shows the manner in which metal removal takes place in the polishing process. Mass removal during process estimated by the same relocation technique is checked with that obtained using weight measurement. The proposed approach can be extended to other micro/nano finishing processes and favorable process conditions can be identified.

  18. Compound antimalarial ethosomal cataplasm: preparation, evaluation, and mechanism of penetration enhancement.

    Science.gov (United States)

    Shen, Shuo; Liu, Shu-Zhi; Zhang, Yu-Shi; Du, Mao-Bo; Liang, Ai-Hua; Song, Li-Hua; Ye, Zu-Guang

    2015-01-01

    Malaria is still a serious public health problem in some parts of the world. The problems of recurrence and drug resistance are increasingly more serious. Thus, it is necessary to develop a novel antimalarial agent. The objectives of this study were to construct a novel compound antimalarial transdermal nanosystem-ethosomal cataplasm, to investigate its characteristics and efficiency, and to systematically explore the penetration-enhancing mechanisms of ethosomal cataplasm. Artesunate-loaded ethosomes and febrifugine-loaded ethosomes were prepared, and their characteristics were evaluated. Drug-loaded ethosomes were incorporated in the matrix of cataplasm to form the compound antimalarial ethosomal cataplasm. With the help of ethosomal technology, the accumulated permeation quantity of artesunate significantly increased at 8 hours after administration, which was 1.57 times as much as that of conventional cataplasm. Soon after administration, the ethosomal cataplasm could make a large quantity of antimalarial drug quickly penetrate through skin, then the remaining drug in the ethosomal cataplasm could be steadily released. These characteristics of ethosomal cataplasm are favorable for antimalarial drugs to kill Plasmodium spp. quickly and prevent the resurgence of Plasmodium spp. As expected, the ethosomal cataplasm showed good antimalarial efficiency in this experiment. The negative conversion rates were 100% and the recurrence rates were 0% at all dosages. The mechanism of penetration enhancement of the ethosomal cataplasm was systematically explored using an optics microscope, polarization microscope, and transmission electron microscopy. The microstructure, ultrastructure, and birefringent structure in skin were observed. Data obtained in this study showed that the application of ethosomal technology to antimalarial cataplasm could improve the transdermal delivery of drug, enhance the efficacy, and facilitate practical application in clinic.

  19. Experimental evaluation of mechanical heart support system based on viscous friction disc pump

    Directory of Open Access Journals (Sweden)

    A. M. Chernyavskiy

    2017-01-01

    Full Text Available Aim. Experimental evaluation of the viscous friction disk pump efficiency, studying the relationship between inter-disk clearance and sizes of input and output ports and pump performance parameters.Materials and methods. To assess the characteristics and to optimize the disk friction pump design the pump model and experimental stand were created. Pump dimensions were set on the basis of medical and biological requirements for mechanical heart support systems and with due consideration of the experimental studies of our colleagues from Pennsylvania. Flow volume of the working fluid was measured by float rotameter Krohne VA-40 with measurement error of not more than 1%. The pressure values in the hydrodynamic circuit were measured using a monitor manufactured by Biosoft-M. Expansion device allowed changing the flow resistance of the system simulating the total peripheral resistance of the circulatory system.Results. Linear direct correlation between the pump performance and the pressure drop of liquid being created at the inlet and outlet of the pump was obtained. The required flow rate (5–7 l/min and pressure (90–100 mmHg were reached when the rotor speed was in the range of 2500–3000 rev/min. It has been shown that the increase of the inlet diameter to 15 mm has not resulted in a significant increase in the pump performance, and that the highest efficiency values can be obtained for the magnitude of inter-disk gap of 0.4–0.5 mm.Conclusion. Designed and manufactured experimental disc pump model for pumping fluid has showed the fundamental possibility to use this model as a system for mechanical support of the heart.

  20. The Effectiveness Evaluation among Different Player-Matching Mechanisms in a Multi-Player Quiz Game

    Science.gov (United States)

    Tsai, Fu-Hsing

    2016-01-01

    This study aims to investigate whether different player-matching mechanisms in educational multi-player online games (MOGs) can affect students' learning performance, enjoyment perception and gaming behaviors. Based on the multi-player quiz game, TRIS-Q, developed by Tsai, Tsai and Lin (2015) using a free player-matching (FPM) mechanism, the same…

  1. Autogenous shrinkage in high-performance cement paste: An evaluation of basic mechanisms

    DEFF Research Database (Denmark)

    Lura, Pietro; Jensen, Ole Mejlhede; van Breugel, Klaas

    2003-01-01

    In this paper, various mechanisms Suggested to cause autogenous shrinkage are presented. The mechanisms are evaluated from the point of view of their soundness and applicability to quantitative modeling of autogenous shrinkage. The capillary tension approach is advantageous, because it has a sound...... mechanical and thermodynamical basis. Furthermore, this mechanism is easily applicable in a numerical model when dealing with a continuously changing microstructure. In order to test the numerical model, autogenous deformation and internal relative humidity (RH) of a Portland cement paste were measured...... on the capillary tension approach. Because a part of the RH drop in the cement paste is due to dissolved salts in the pore solution, a method is suggested to separate this effect from self-desiccation and to calculate the actual stress in the pore fluid associated with menisci formation....

  2. Mechanisms of Osteoarthritic Pain. Studies in Humans and Experimental Models

    Directory of Open Access Journals (Sweden)

    Annett Eitner

    2017-11-01

    Full Text Available Pain due to osteoarthritis (OA is one of the most frequent causes of chronic pain. However, the mechanisms of OA pain are poorly understood. This review addresses the mechanisms which are thought to be involved in OA pain, derived from studies on pain mechanisms in humans and in experimental models of OA. Three areas will be considered, namely local processes in the joint associated with OA pain, neuronal mechanisms involved in OA pain, and general factors which influence OA pain. Except the cartilage all structures of the joints are innervated by nociceptors. Although the hallmark of OA is the degradation of the cartilage, OA joints show multiple structural alterations of cartilage, bone and synovial tissue. In particular synovitis and bone marrow lesions have been proposed to determine OA pain whereas the contribution of the other pathologies to pain generation has been studied less. Concerning the peripheral neuronal mechanisms of OA pain, peripheral nociceptive sensitization was shown, and neuropathic mechanisms may be involved at some stages. Structural changes of joint innervation such as local loss and/or sprouting of nerve fibers were shown. In addition, central sensitization, reduction of descending inhibition, descending excitation and cortical atrophies were observed in OA. The combination of different neuronal mechanisms may define the particular pain phenotype in an OA patient. Among mediators involved in OA pain, nerve growth factor (NGF is in the focus because antibodies against NGF significantly reduce OA pain. Several studies show that neutralization of interleukin-1β and TNF may reduce OA pain. Many patients with OA exhibit comorbidities such as obesity, low grade systemic inflammation and diabetes mellitus. These comorbidities can significantly influence the course of OA, and pain research just began to study the significance of such factors in pain generation. In addition, psychologic and socioeconomic factors may aggravate

  3. Fracture mechanics evaluation for the cast duplex stainless steel after thermal aging

    Energy Technology Data Exchange (ETDEWEB)

    Urata, Shigeru [Kansai Electric Power Co., Inc., Osaka (Japan)

    1998-12-31

    For the primary coolant piping of PWRs in Japan, cast duplex stainless steel which is excellent in terms of strength, corrosion resistance, and weldability has conventionally been used. The cast duplex stainless steel contains the ferrite phase in the austenite matrix and thermal aging after long term service is known to change its material characteristics. It is considered appropriate to apply the methodology of elastic plastic fracture mechanics for an evaluation of the integrity of the primary coolant piping after thermal aging. Therefore, we evaluated the integrity of the primary coolant piping for an initial PWR plant in Japan by means of elastic plastic fracture mechanics. The evaluation results show that the crack will not grow into an unstable fracture and the integrity of the piping will be secured, even when such through wall crack length is assumed to equal the fatigue crack growth length for a service period of up to 60 years. (author)

  4. Added value of cardiac computed tomography for evaluation of mechanical aortic valve: Emphasis on evaluation of pannus with surgical findings as standard reference.

    Science.gov (United States)

    Suh, Young Joo; Lee, Sak; Im, Dong Jin; Chang, Suyon; Hong, Yoo Jin; Lee, Hye-Jeong; Hur, Jin; Choi, Byoung Wook; Chang, Byung-Chul; Shim, Chi Young; Hong, Geu-Ru; Kim, Young Jin

    2016-07-01

    The added value of cardiac computed tomography (CT) with transesophageal echocardiography (TEE) for evaluating mechanical aortic valve (AV) dysfunction has not yet been investigated. The purposes of this study were to investigate the added value of cardiac CT for evaluation of mechanical AVs and diagnoses of pannus compared to TEE, with surgical findings of redo-aortic valve replacement (AVR) used as a standard reference. 25 patients who underwent redo-AVR due to mechanical AV dysfunction and cardiac CT before redo-AVR were included. The presence of pannus, encroachment ratio by pannus, and limitation of motion (LOM) were evaluated on CT. The diagnostic performance of pannus detection was compared using TEE, CT, and CT+TEE, with surgical findings as a standard reference. The added value of CT for diagnosing the cause of mechanical AV dysfunction was assessed compared to TTE+TEE. In two patients, CT analysis was not feasible due to severe metallic artifacts. On CT, pannus and LOM were found in 100% (23/23) and 60.9% (14/23). TEE identified pannus in 48.0% of patients (12/25). CT, TEE, and CT+TEE correctly identified pannus with sensitivity of 92.0%, 48.0%, and 92.0%, respectively (P=0.002 for CT vs. TEE). In 11 of 13 cases (84.6%) with inconclusive or negative TEE results for pannus, CT detected the pannus. Among 13 inconclusive cases of TTE+TEE for the cause of mechanical AV dysfunction, CT suggested 6 prosthetic valve obstruction (PVO) by pannus, 4 low-flow low-gradient PVO, and one LOM without significant PVO. Cardiac CT showed added diagnostic value with TEE in the detection of pannus as the cause of mechanical AV dysfunction. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  5. Preliminary study of mechanical behavior for Cr coated Zr-4 Fuel Cladding

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Do-Hyoung; Kim, Hak-Sung [Hanyang Univ., Seoul (Korea, Republic of); Kim, Hyo-Chan; Yang, Yong-Sik [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    To decrease the oxidation rate of Zr-based alloy components, many concepts of accident tolerant fuel (ATF) such as Mo-Zr cladding, SiC/SiCf cladding and iron-based alloy cladding are under development. One of the promised concept is the coated cladding which can remarkably increase the corrosion and wear resistance. Recently, KAERI is developing the Cr coated Zircaloy cladding as accident tolerance cladding. To coat the Cr powder on the Zircaloy, 3D laser coating technology has been employed because it is possible to make a coated layer on the tubular cladding surface by controlling the 3-diminational axis. Therefore, for this work, the mechanical integrity of Cr coated Zircaloy should be evaluated to predict the safety of fuel cladding during the operating or accident of nuclear reactor. In this work, the mechanical behavior of the Cr coated Zircaloy cladding has been studied by using finite element analysis (FEA). The ring compression test (RCT) of fuel cladding was simulated to evaluate the validity of mechanical properties of Zr-4 and Cr, which were referred from the literatures and experimental reports. In this work, the mechanical behavior of the Cr coated Zircaloy cladding has been studied by using finite element analysis (FEA). The ring compression test (RCT) of fuel cladding was simulated to evaluate the validity of mechanical properties of Zr-4 and Cr. The pellet-clad mechanical interaction (PCMI) properties of Cr coated Zr-4 cladding were investigated by thermo-mechanical finite element analysis (FEA) simulation. The mechanical properties of Zr-4 and Cr was validated by simulation of ring compression test (RCT) of fuel cladding.

  6. A Case Study of Knowledge Exchange in a Hierarchical Mechanism

    Directory of Open Access Journals (Sweden)

    Indria Handoko

    2017-04-01

    Full Text Available This research investigates knowledge exchange in an organization applying hierarchical mechanisms, and the influence of social interactions on knowledge flow across different levels of analysis. The research uses a qualitative case study method of an Indonesian automotive component-making company, applying semi-structured interviews, observations, and focus groups at interorganizational, internal company, and shop floor levels. The research main finding is that in an organization applying hierarchical mechanisms, social interactions that exist at one level are able to influence interactions at other levels, and that the interactions can both facilitate and inhibit knowledge exchange across levels and boundaries. The application of any formal mechanism at interorganizational level needs to consider both the dynamics operating at social level and the potentially disparate and contradictory effects it may have if its aim is to promote knowledge flow across levels. The application of in-depth exploratory case study research contributes to the conceptualization of relationships between knowledge exchange, social interactions, and governance mechanism.

  7. NDE and fracture mechanics evaluation of bottom-head weld indications in a BWR reactor pressure vessel

    Energy Technology Data Exchange (ETDEWEB)

    Brickstad, B [Swedish Plant Inspectorate, Stockholm (Sweden)

    1988-12-31

    This document deals with the Non Destructive Examination (NDE) and the fracture mechanics evaluation of bottom head welds in a BWR. The NDE equipment is presented, together with the geometry of evaluated flaw regions. After the fracture mechanics evaluation, it appeared that the plant results fulfilled the usual conditions, and the plant was allowed to operate one more year. (TEC).

  8. Mechanical Performance Evaluation of Self-Compacting Concrete with Fine and Coarse Recycled Aggregates from the Precast Industry.

    Science.gov (United States)

    Santos, Sara A; da Silva, Pedro R; de Brito, Jorge

    2017-08-04

    This paper intends to evaluate the feasibility of reintroducing recycled concrete aggregates in the precast industry. The mechanical properties of self-compacting concrete (SCC) with incorporation of recycled aggregates (RA) (coarse recycled aggregates (CRA) and fine recycled aggregates (FRA)) from crushed precast elements were evaluated. The goal was to evaluate the ability of producing SCC with a minimum pre-established performance in terms of mechanical strength, incorporating variable ratios of RA (FRA/CRA%: 0/0%, 25/25%, 50/50%, 0/100% and 100/0%) produced from precast source concretes with similar target performances. This replication in SCC was made for two strength classes (45 MPa and 65 MPa), with the intention of obtaining as final result concrete with recycled aggregates whose characteristics are compatible with those of a SCC with natural aggregates in terms of workability and mechanical strength. The results enabled conclusions to be established regarding the SCC's produced with fine and coarse recycled aggregates from the precast industry, based on its mechanical properties. The properties studied are strongly affected by the type and content of recycled aggregates. The potential demonstrated, mainly in the hardened state, by the joint use of fine and coarse recycled aggregate is emphasized.

  9. An Evaluative Study of the Defense Mechanism Test

    Science.gov (United States)

    1990-07-01

    massive increase in this effect. The use of a parallel test with more dissimilar stimuli is also not a practicable option, as in this case results would no...training" was practically null (0.07). In order to be sure that this result was not simply due to inappropriate application of Swedish weightings of the...the threatening image is a father figure, catching the boy masturbating (the violin being a phallic symbol). Unsuccessful candidates In the test have

  10. Removal torque evaluation of three different abutment screws for single implant restorations after mechanical cyclic loading.

    Science.gov (United States)

    Paepoemsin, T; Reichart, P A; Chaijareenont, P; Strietzel, F P; Khongkhunthian, P

    2016-01-01

    The aim of this study was to evaluate the removal torque of three different abutment screws and pull out strength of implant-abutment connection for single implant restorations after mechanical cyclic loading. The study was performed in accordance with ISO 14801:2007. Three implant groups (n=15) were used: group A, PW Plus® with flat head screw; group B, PW Plus® with tapered screw; and group C, Conelog® with flat head screw. All groups had the same implant-abutment connection feature: cone with mandatory index. All screws were tightened with manufacturer's recommended torque. Ten specimens in each group underwent cyclic loading (1×106 cycles, 10 Hz, and 250 N). Then, all specimens were un-tightened, measured for the removal torque, and underwent a tensile test. The force that dislodged abutment from implant fixture was recorded. The data were analysed using independent sample t-test, ANOVA and Tukey HSD test. Before cyclic loading, removal torque in groups A, B and C were significantly different (B> A> C, Pabutment from implant fixture increased immensely after cyclic loading.

  11. Mechanical Evaluation for the Quality Control of Biomass Pellets and Briquettes

    Energy Technology Data Exchange (ETDEWEB)

    Freitas Seabra da Rocha, Saulo Henrique [RWTH Aachen Univ. (Germany). KoBrA - Coking, Briquetting and Thermal Waste Treatment Group

    2006-07-15

    Biomass densification through compression machine leads to numerous benefits, such as decreased dust emission, transportation, and maintenance costs. However, if the mechanical strength of the Pellets and briquettes is not high enough, breaks and abrasion lead to low efficiency. Quality evaluation before pelleting or briquetting can avoid these problems. The most common mechanical strength evaluation methods are simple and fast, but their accuracy and precision are limited. In this paper three methods for mechanical strength evaluation are reviewed, tested and statistically compared. Compacted bodies in different dimensions of typical materials, like sawdust, bark and lignite, were produced, and tested with the mentioned methods to get different values of mechanical strength. The correlation coefficient was used to compare the accuracy and precision of those methods. The Point Load Strength method showed a linear variation error and a poor correlation coefficient value (R2 = 0.71-0.78). The Brazilian Test had a reasonably constant result, but the relative standard deviation was 22%, insufficient for a practical process optimization. The best results were produced from the Extended Planar Strength, with an excellent correlation coefficient value (R2 = 0.98). This technique will help to increase efficiency and save energy in the production process.

  12. Mechanics

    CERN Document Server

    Hartog, J P Den

    1961-01-01

    First published over 40 years ago, this work has achieved the status of a classic among introductory texts on mechanics. Den Hartog is known for his lively, discursive and often witty presentations of all the fundamental material of both statics and dynamics (and considerable more advanced material) in new, original ways that provide students with insights into mechanical relationships that other books do not always succeed in conveying. On the other hand, the work is so replete with engineering applications and actual design problems that it is as valuable as a reference to the practicing e

  13. Evaluation of mechanical precision and alignment uncertainties for an integrated CT/LINAC system

    International Nuclear Information System (INIS)

    Court, Laurence; Rosen, Isaac; Mohan, Radhe; Dong Lei

    2003-01-01

    A new integrated CT/LINAC combination, in which the CT scanner is inside the radiation therapy treatment room and the same patient couch is used for CT scanning and treatment (after a 180-degree couch rotation), should allow for accurate correction of interfractional setup errors. The purpose of this study was to evaluate the sources of uncertainties, and to measure the overall precision of this system. The following sources of uncertainty were identified: (1) the patient couch position on the LINAC side after a rotation, (2) the patient couch position on the CT side after a rotation, (3) the patient couch position as indicated by its digital readout, (4) the difference in couch sag between the CT and LINAC positions, (5) the precision of the CT coordinates, (6) the identification of fiducial markers from CT images, (7) the alignment of contours with structures in the CT images, and (8) the alignment with setup lasers. The largest single uncertainties (one standard deviation or 1 SD) were found in couch position on the CT side after a rotation (0.5 mm in the RL direction) and the alignment of contours with the CT images (0.4 mm in the SI direction). All other sources of uncertainty are less than 0.3 mm (1 SD). The overall precision of two setup protocols was investigated in a controlled phantom study. A protocol that relies heavily on the mechanical integrity of the system, and assumes a fixed relationship between the LINAC isocenter and the CT images, gave a predicted precision (1 SD) of 0.6, 0.7, and 0.6 mm in the SI, RL and AP directions, respectively. The second protocol reduces reliance on the mechanical precision of the total system, particularly the patient couch, by using radio-opaque fiducial markers to transfer the isocenter information from the LINAC side to the CT images. This protocol gave a slightly improved predicted precision of 0.5, 0.4, and 0.4 mm in the SI, RL and AP directions, respectively. The distribution of phantom position after CT

  14. Evaluation of an Online Study Skills Course

    Science.gov (United States)

    Pryjmachuk, Steven; Gill, Anita; Wood, Patricia; Olleveant, Nicola; Keeley, Philip

    2012-01-01

    This article describes the evaluation of an online study skills course unit designed, using evidence-based principles, to support undergraduate students. A mixed-methods approach was employed to establish the extent to which the unit was (a) fit for purpose and (b) effective. Data were obtained from an online survey (n = 63) conducted on entry to…

  15. Using hierarchical linear growth models to evaluate protective mechanisms that mediate science achievement

    Science.gov (United States)

    von Secker, Clare Elaine

    The study of students at risk is a major topic of science education policy and discussion. Much research has focused on describing conditions and problems associated with the statistical risk of low science achievement among individuals who are members of groups characterized by problems such as poverty and social disadvantage. But outcomes attributed to these factors do not explain the nature and extent of mechanisms that account for differences in performance among individuals at risk. There is ample theoretical and empirical evidence that demographic differences should be conceptualized as social contexts, or collections of variables, that alter the psychological significance and social demands of life events, and affect subsequent relationships between risk and resilience. The hierarchical linear growth models used in this dissertation provide greater specification of the role of social context and the protective effects of attitude, expectations, parenting practices, peer influences, and learning opportunities on science achievement. While the individual influences of these protective factors on science achievement were small, their cumulative effect was substantial. Meta-analysis conducted on the effects associated with psychological and environmental processes that mediate risk mechanisms in sixteen social contexts revealed twenty-two significant differences between groups of students. Positive attitudes, high expectations, and more intense science course-taking had positive effects on achievement of all students, although these factors were not equally protective in all social contexts. In general, effects associated with authoritative parenting and peer influences were negative, regardless of social context. An evaluation comparing the performance and stability of hierarchical linear growth models with traditional repeated measures models is included as well.

  16. Mechanical characteristic evaluation of the mid grid spring in PWR fuel assembly

    International Nuclear Information System (INIS)

    Eum, K. B.; Lee, S. H.; Jeon, S. Y.; Kweon, Y. B.; Jeon, K. R.

    2001-01-01

    The spring load-deflection characteristic tests were performed for Westinghouse type 17x17 and 14x14 fuel assembly mid grids to evaluate the mechanical characteristics of the springs. Six kinds of prototype mid grids manufactured by KNFC were tested and two kinds of test methods were used: block test and in-grid test. The test results showed that all tested mid grid springs satisfied the criteria required at the beginning of fuel assembly life. In addition, the variation of spring characteristics resulting from the difference in the mechanical properties of spring material and spring shapes was investigated. And the validity of the test methods was discussed

  17. Using Vector Projection Method to evaluate maintainability of mechanical system in design review

    International Nuclear Information System (INIS)

    Chen Lu; Cai Jianguo

    2003-01-01

    Maintainability of a mechanical system is one of the system design parameters that has a great impact in terms of ease of maintenance. In this article, based on the definition of the terms of maintenance and maintainability, an important tool of Design for Maintenance is developed as a way to improve maintainability through design. A set of standard and organized guidelines is provided and maintainability factors in terms of physical design, logistics support and ergonomics are identified. As a specific application of design review, a methodology so called Vector Projection Method is developed to evaluate the maintainability of the mechanical system. Lastly, an example is discussed

  18. Bithionol inhibits ovarian cancer cell growth In Vitro - studies on mechanism(s) of action

    International Nuclear Information System (INIS)

    Ayyagari, Vijayalakshmi N; Brard, Laurent

    2014-01-01

    ovarian cancer cell lines regardless of their sensitivities to cisplatin. Cell death appears to be via caspases mediated apoptosis. The mechanisms of action appear to be partly via cell cycle arrest, ROS generation and inhibition of ATX. The present study provides preclinical data suggesting a potential therapeutic role for BT against recurrent ovarian cancer

  19. Quantum mechanical simulation methods for studying biological systems

    International Nuclear Information System (INIS)

    Bicout, D.; Field, M.

    1996-01-01

    Most known biological mechanisms can be explained using fundamental laws of physics and chemistry and a full understanding of biological processes requires a multidisciplinary approach in which all the tools of biology, chemistry and physics are employed. An area of research becoming increasingly important is the theoretical study of biological macromolecules where numerical experimentation plays a double role of establishing a link between theoretical models and predictions and allowing a quantitative comparison between experiments and models. This workshop brought researchers working on different aspects of the development and application of quantum mechanical simulation together, assessed the state-of-the-art in the field and highlighted directions for future research. Fourteen lectures (theoretical courses and specialized seminars) deal with following themes: 1) quantum mechanical calculations of large systems, 2) ab initio molecular dynamics where the calculation of the wavefunction and hence the energy and forces on the atoms for a system at a single nuclear configuration are combined with classical molecular dynamics algorithms in order to perform simulations which use a quantum mechanical potential energy surface, 3) quantum dynamical simulations, electron and proton transfer processes in proteins and in solutions and finally, 4) free seminars that helped to enlarge the scope of the workshop. (N.T.)

  20. Mechanical study of a modern yo-yo

    International Nuclear Information System (INIS)

    De Izarra, Charles

    2011-01-01

    This paper presents the study of a modern yo-yo having a centrifugal clutch allowing the free rolling. First, the mechanical parts of the yo-yo are measured, allowing us to determine analytically its velocity according to its height of fall. Then, we are more particularly interested in the centrifugal device constituted by springs and small masses. The physics of this toy is suitable for undergraduate students, illustrating the concepts of dynamics of rigid bodies and of potential energy.

  1. Studying structurally-mechanical characteristics suppositories with amlodipine

    Directory of Open Access Journals (Sweden)

    Fadi Al Zedan

    2013-02-01

    Full Text Available Rheological behaviour suppositories with amlodipine on lypofiles to a basis are studied and character of temperature effect on their structurally-mechanical properties is positioned. It is revealed that the temperature of carrying out of technological operations of homogenization and overflow suppositories 50-55ºС is optimum, providing necessary fluidity suppositories masses at hypodispersion in it reacting and aids.

  2. Radiotracer studies on molecular mechanisms of death and resuscitation

    International Nuclear Information System (INIS)

    Nikulin, V.J.; Pogossova, A.V.; Konikova, A.S.

    1980-01-01

    Tracer techniques and artificial circulation were applied to rabbits after death by anoxia and deep hypothermia in order to study molecular mechanisms. 60 min after death the biosynthesis and disintegration of protein RNA and DNA practically stopped in all organs. In animals cooled post mortem the process of biosynthesis and degradation of protein, RNA and DNA, as well as the physiological functions of the whole organism, were restored. (author)

  3. Study of glass alteration mechanisms in cement waters

    International Nuclear Information System (INIS)

    Depierre, S.

    2012-01-01

    In the French deep geological repository concept, intermediate-level vitrified waste packages could be disposed of concrete medium. Chemical composition and pH of the interstitial leaching water are expected to influence the chemical durability of glass. Investigations have thus been carried out to study glass dissolution mechanisms and kinetics in contact with cement waters. Three cement pore waters were studied: the first two correspond to two stages of the Portland cement aging and the third corresponds to equilibrium with a low pH concrete. The S/V ratio (glass-surface-area-to-solution-volume ratio) and the chemistry of cement waters are the two main parameters that control glass alteration mechanisms. If the leaching flow from the glass allows a degree of supersaturation to be reached and maintained which leads to nucleation of secondary phases, then precipitation of these phases drives glass dissolution. At a very low S/V ratio, the calcium uptake into the alteration layer increases its passivating properties. Conversely, at a high S/V ratio, the calcium precipitates as cementitious phases consuming elements which form the alteration layer. The glass dissolution is maintained at a high rate. This study contributes to highlighting the beneficial role of low pH cement in glass alteration, and is a first step towards understanding the mechanisms between the glass and the cement medium. (author) [fr

  4. In vitro evaluation of ionizing radiation effects in bone tissue by FTIR spectroscopy and dynamic mechanical analysis

    International Nuclear Information System (INIS)

    Veloso, Marcelo Noronha

    2013-01-01

    Ionizing radiation from gamma radiation sources or X-ray generators is frequently used in Medical Science, such as radiodiagnostic exams, radiotherapy, and sterilization of haloenxerts. Ionizing radiation is capable of breaking polypeptidic chains and causing the release of free radicals by radiolysis.of water. It interacts also with organic material at the molecular level, and it may change its mechanical properties. In the specific case of bone tissue, studies report that ionizing radiation induces changes in collagen molecules and reduces the density of intermolecular crosslinks. The aim of this study was to verify the changes promoted by different doses of ionizing radiation in bone tissue using Fourier Transform Infrared Spectroscopy (FTIR) and dynamic mechanical analysis (DMA). Samples of bovine bone were irradiated using Cobalt-60 with five different doses: 0.01 kGy, 0.1 kGy, 1 kGy, 15 kGy and 75 kGy. To study the effects of ionizing irradiation on the chemical structure of the bone, the sub-bands of amide I, the crystallinity index and relation of organic and inorganic materials, were studied. The mechanical changes were evaluated using the elastic modulus and the damping value. To verify whether the chemical changes and the mechanical characteristics of the bone were correlated, the relation between the analysis made with spectroscopic data and the mechanical analysis data was studied. It was possible to evaluate the effects of different doses of ionizing radiation in bone tissue. With ATR-FTIR spectroscopy, it was possible to observe changes in the organic components and in the hydroxyapatite crystals organization. Changes were also observed in the elastic modulus and in the damping value. High correlation with statistical significance was observed among (amide III + collagen)/ v1,v3 , PO 4 3- and the delta tangent, and among 1/FHWM and the elastic modulus. (author)

  5. Mechanical performance evaluation of bionanocomposites with polymeric matrix of poly(lactic acid)-PLA and organo clay

    International Nuclear Information System (INIS)

    Cavalcanti, Shirley N.; Melo, Tomas J.A. de; Araujo, Edcleide M.; Oliveira, Akidauana D.A.; Lima, Jessica C.C.

    2011-01-01

    The aim of this study is to evaluate the influence of ethylene/methyl acrylate (EMA) and ethylene/glycidyl methacrylate (E-GMA) copolymers and organoclay on the mechanical properties of polymer PLA-poly (lactic acid), from the system PLA / organoclay. The clay was organophilized with the ionic surfactant praepagem and the mixtures were prepared in a modular twin screw extruder. The behavior of bionanocomposites was evaluated by tensile and impact tests. The results of FTIR and DR-X indicated that the process was efficient organophilization. The mechanical properties showed that the elastic modulus and tensile strength of bionanocomposites obtained decreased compared to PLA. On the other hand there was a gain for resistance to impact, for all systems except for system PLA/OMMT. (author)

  6. Psychophysical evaluation of a sanshool derivative (alkylamide and the elucidation of mechanisms subserving tingle.

    Directory of Open Access Journals (Sweden)

    Kelly C Albin

    2010-03-01

    Full Text Available Previous studies investigated the neural and molecular underpinnings of the tingle sensation evoked by sanshool and other natural or synthetic alkylamides. Currently, we sought to characterize the psychophysical properties associated with administration of these compounds. Like other chemesthetic stimuli, the synthetic tingle analog isobutylalkylamide (IBA evoked a sensation that was temporally dynamic. Repeated IBA application at short (30 sec interstimulus intervals (ISI resulted in a tingle sensation that increased across trials. Application at longer ISIs (approximately 30 min resulted in a sensation of decreased intensity consistent with self-desensitization. Prior treatment with the TRPV1 or TRPA1 agonists, capsaicin and mustard oil did not cross-desensitize the tingle sensation evoked by IBA suggesting that neither TRPV1 nor TRPA1 participate in the transduction mechanism sub-serving tingle. When evaluated over 30-min time period, lingual IBA evoked a sensation that was described initially as tingling and pungent but after approximately 15 min, as a cooling sensation. Further, we found that the sensation evoked by lingual IBA was potentiated by simultaneous application of cold (0 degrees C and cool (21 degrees C thermal stimuli but was unaffected by warm (33 degrees C and hot (41 degrees C temperatures. Finally, to test the hypothesis that the tingling sensation is subserved by the activation of mechanosensitve fibers, we evaluated lingual tactile thresholds in the presence and absence of lingual IBA. The presence of IBA significantly raised lingual tactile thresholds, whereas capsaicin did not, identifying a role for mechanosensitive fibers in conveying the tingle sensation evoked by sanshool-like compounds. Collectively, these results show that lingual alkylamide evokes a complex sensation that is temporally dynamic and consistent with in vitro and in vivo experiments suggesting these compounds activate mechanosensitve neurons via

  7. Lubrication Theory Model to Evaluate Surgical Alterations in Flow Mechanics of the Lower Esophageal Sphincter

    Science.gov (United States)

    Ghosh, Sudip K.; Brasseur, James G.; Zaki, Tamer; Kahrilas, Peter J.

    2003-11-01

    Surgery is commonly used to rebuild a weak lower esophageal sphincter (LES) and reduce reflux. Because the driving pressure (DP) is proportional to muscle tension generated in the esophagus, we developed models using lubrication theory to evaluate the consequences of surgery on muscle force required to open the LES and drive the flow. The models relate time changes in DP to lumen geometry and trans-LES flow with a manometric catheter. Inertial effects were included and found negligible. Two models, direct (opening specified) and indirect (opening predicted), were combined with manometric pressure and imaging data from normal and post-surgery LES. A very high sensitivity was predicted between the details of the DP and LES opening. The indirect model accurately captured LES opening and predicted a 3-phase emptying process, with phases I and III requiring rapid generation of muscle tone to open the LES and empty the esophagus. Data showed that phases I and III are adversely altered by surgery causing incomplete emptying. Parametric model studies indicated that changes to the surgical procedure can positively alter LES flow mechanics and improve clinical outcomes.

  8. The sedative effects and mechanism of action of cedrol inhalation with behavioral pharmacological evaluation.

    Science.gov (United States)

    Kagawa, Daiji; Jokura, Hiroko; Ochiai, Ryuji; Tokimitsu, Ichiro; Tsubone, Hirokazu

    2003-07-01

    It has been reported that cedarwood oil has sedative effects when inhaled. In this study, we evaluated sedative effects of inhaled cedrol, which is a major component of cedarwood oil. Accumulative spontaneous motor activity was significantly decreased in the cedrol-exposed Wistar rats. Similar results were confirmed in caffeine-treated Wistar rats, spontaneously hypertensive rats (SHR), and ddY mice. In addition, exposure to cedrol prolonged pentobarbital-induced sleeping time in Wistar rats. To investigate whether cedrol, which has a very faint aroma, affects the olfactory system, the nasal cavities of Wistar rats were treated with zinc sulfate to reduce olfactory function. Two days later, the pentobarbital-induced sleep time was measured as described above. Compared to intact rats, the sleep prolongation effect was decreased in a lavender-roman chamomile mixed oil exposure positive control group, indicating that olfactory function was impaired. In contrast, prolongation of the sleeping time did not change in the cedrol exposure group. The above findings indicate that cedrol inhalation had marked sedative effects regardless of the animal species or the functional state of the autonomic nerves, suggesting that the mechanism of action is via a pathway other than the olfactory system.

  9. Performance Evaluation of a Mechanical Draft Cross Flow Cooling Towers Employed in a Subtropical Region

    Science.gov (United States)

    Muthukumar, Palanisamy; Naik, Bukke Kiran; Goswami, Amarendra

    2018-02-01

    Mechanical draft cross flow cooling towers are generally used in a large-scale water cooled condenser based air-conditioning plants for removing heat from warm water which comes out from the condensing unit. During this process considerable amount of water in the form of drift (droplets) and evaporation is carried away along with the circulated air. In this paper, the performance evaluation of a standard cross flow induced draft cooling tower in terms of water loss, range, approach and cooling tower efficiency are presented. Extensive experimental studies have been carried out in three cooling towers employed in a water cooled condenser based 1200 TR A/C plant over a period of time. Daily variation of average water loss and cooling tower performance parameters have been reported for some selected days. The reported average water loss from three cooling towers is 4080 l/h and the estimated average water loss per TR per h is about 3.1 l at an average relative humidity (RH) of 83%. The water loss during peak hours (2 pm) is about 3.4 l/h-TR corresponding to 88% of RH and the corresponding efficiency of cooling towers varied between 25% and 45%.

  10. Mechanical evaluation of bone gap filled with rigid formulations castor oil polyurethane and chitosan in horses

    Directory of Open Access Journals (Sweden)

    Rodrigo Crispim Moreira

    Full Text Available ABSTRACT: Often fractures of long bones in horses are comminuted and form bone gaps, which represent a major challenge for the fixation of these fractures by loss of contact between the fragments. Bone grafts help in treating this kind of fracture and synthetic materials have been gaining ground because of the limitations of autologous and heterologous grafts. In this study were performed compressive non destructive test in 10 bones with complete cross-bone gap in mid-diaphyseal of the third metacarpal bone of horses. Using a mechanism of "crossing" the 10 bones were used in the three groups (control, castor oil poliuretane and chitosan according to the filling material. After the test with maximum load of 1000N bone had a gap filled by another material and the test was repeated. Deformations caused on the whole bone, plate and bone tissue near and distant of gap were evaluated, using strain gauges adhered to the surface at these locations. There was a reduction in bone deformation from 14% (control to 3,5% and 4,8% by filling the gap with Chitosan and castor oil respectively, and a reduction of strain on the plate of 96% and 85% by filling gap with chitosan and castor respectively. An increase in intensity and direction of deformations occurred in bone near to gap after its filling; however, there was no difference in bone deformations occurring far the gap.

  11. Evaluation of major heat waves' mechanisms in EURO-CORDEX RCMs over Central Europe

    Science.gov (United States)

    Lhotka, Ondřej; Kyselý, Jan; Plavcová, Eva

    2018-06-01

    The main aim of the study is to evaluate the capability of EURO-CORDEX regional climate models (RCMs) to simulate major heat waves in Central Europe and their associated meteorological factors. Three reference major heat waves (1994, 2006, and 2015) were identified in the E-OBS gridded data set, based on their temperature characteristics, length and spatial extent. Atmospheric circulation, precipitation, net shortwave radiation, and evaporative fraction anomalies during these events were assessed using the ERA-Interim reanalysis. The analogous major heat waves and their links to the aforementioned factors were analysed in an ensemble of EURO-CORDEX RCMs driven by various global climate models in the 1970-2016 period. All three reference major heat waves were associated with favourable circulation conditions, precipitation deficit, reduced evaporative fraction and increased net shortwave radiation. This joint contribution of large-scale circulation and land-atmosphere interactions is simulated with difficulties in majority of the RCMs, which affects the magnitude of modelled major heat waves. In some cases, the seemingly good reproduction of major heat waves' magnitude is erroneously achieved through extremely favourable circulation conditions compensated by a substantial surplus of soil moisture or vice versa. These findings point to different driving mechanisms of major heat waves in some RCMs compared to observations, which should be taken into account when analysing and interpreting future projections of these events.

  12. Evaluating Amazon's Mechanical Turk as a tool for experimental behavioral research.

    Directory of Open Access Journals (Sweden)

    Matthew J C Crump

    Full Text Available Amazon Mechanical Turk (AMT is an online crowdsourcing service where anonymous online workers complete web-based tasks for small sums of money. The service has attracted attention from experimental psychologists interested in gathering human subject data more efficiently. However, relative to traditional laboratory studies, many aspects of the testing environment are not under the experimenter's control. In this paper, we attempt to empirically evaluate the fidelity of the AMT system for use in cognitive behavioral experiments. These types of experiment differ from simple surveys in that they require multiple trials, sustained attention from participants, comprehension of complex instructions, and millisecond accuracy for response recording and stimulus presentation. We replicate a diverse body of tasks from experimental psychology including the Stroop, Switching, Flanker, Simon, Posner Cuing, attentional blink, subliminal priming, and category learning tasks using participants recruited using AMT. While most of replications were qualitatively successful and validated the approach of collecting data anonymously online using a web-browser, others revealed disparity between laboratory results and online results. A number of important lessons were encountered in the process of conducting these replications that should be of value to other researchers.

  13. Evaluation of mechanical properties for spherical magnetic regenerator materials fabricated by rapid solidification process

    International Nuclear Information System (INIS)

    Okamura, M.; Sori, N.; Saito, A.

    1997-01-01

    Various magnetic regenerator materials, such as Er 3 Ni, Er 3 Co and ErNi, are fabricated in the form of a spherical particle by a rapid solidification process. 4 K level refrigeration has been obtained by a GM refrigerator using these materials. However, the magnetic regenerator materials are considered brittle, as they are intermetallic compounds. It is important to evaluate the mechanical properties of these materials to confirm reliability as a regenerator material. In this paper, experimental results of compression and vibration tests for magnetic regenerator materials are described. The technical point of this study is to use spherical particles as test samples. The compressive stress of 20 MPa was applied to these spherical particles and no fractured spheres were observed. Similarly, no fractured spheres were found after the vibration test, in which the maximum acceleration was 30 X 9.8 m/s 2 and the number of vibration times was 1 X 10 6 , insofar as there was no room to stir spherical particles in a regenerator. In practice, the reliability of magnetic regenerator materials has been confirmed by a long-run test of 7,000 h in a usual GM refrigerator

  14. How beauty works. Theoretical mechanisms and two empirical applications on students' evaluation of teaching.

    Science.gov (United States)

    Wolbring, Tobias; Riordan, Patrick

    2016-05-01

    Plenty of studies show that the physical appearance of a person affects a variety of outcomes in everyday life. However, due to an incomplete theoretical explication and empirical problems in disentangling different beauty effects, it is unclear which mechanisms are at work. To clarify how beauty works we present explanations from evolutionary theory and expectation states theory and show where both perspectives differ and where interlinkage appears promising. Using students' evaluations of teaching we find observational and experimental evidence for the different causal pathways of physical attractiveness. First, independent raters strongly agree over the physical attractiveness of a person. Second, attractive instructors receive better student ratings. Third, students attend classes of attractive instructors more frequently - even after controlling for teaching quality. Fourth, we find no evidence that attractiveness effects become stronger if rater and ratee are of the opposite sex. Finally, the beauty premium turns into a penalty if an attractive instructor falls short of students' expectations. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Mechanical thermal evaluation of polyamide 6 with bentonite organo clay nanocomposites

    International Nuclear Information System (INIS)

    Paz, Rene Anisio da; Araujo, Edcleide M.; Melo, Tomas Jeferson Alves de; Leite, Amanda M.D.; Cavalcanti, Shirley Nobrega; Pessan, Luiz Antonio

    2009-01-01

    This work had for objective to obtain polymeric nanocomposites of polyamide 6 and a clay consisting of silicates layer from of Paraiba mines and to evaluate evaluation mechanical thermal in different processing conditions. The clay was organically modified using a quaternary ammonium salt (Cetremide), so that there is a larger interaction of the clay with the polymer. The obtained nanocomposites showed the morphological structure composed exfoliated/partially exfoliated, as shown XRD. The results of HDT it because the clay increases the dimensional stability of PA6 in high temperatures, making possible the use of the nanocomposites for making of pieces with good resistance to the heat distortion. (author)

  16. Twenty years of fracture mechanics and flaw evaluation applications in the ASME Nuclear Code

    International Nuclear Information System (INIS)

    Riccardella, P.C.

    1991-01-01

    The paper presents a retrospective on the development and applications of fracture mechanics-based toughness requirements and flaw evaluation methodology in Sections III and XI of the ASME Code. Section III developments range from the rules and requirements for thick section Class 1 pressure vessels to thinner section components in other Classes. Section XI applications include flaw acceptance standards and evaluation methodology for various components ranging from pressure vessels to thins section piping of carbon and austenitic steels. The experience gained in operating plant applications of these rules and procedures are also discussed

  17. Field evaluation of cutter and feeder mechanism of chickpea harvester for lentil harvesting

    Directory of Open Access Journals (Sweden)

    S Kamgar

    2016-09-01

    Full Text Available Introduction The main producers of lentil are Canada, India, Nepal and China, respectively and Iran is the ninth producer in the world. The hand pulling is the usual method of lentil harvesting. Use of conventional combine because of short leg varieties, wide combine head in dry land and grain losses by cutter bar vibrations is impossible. So a mechanism should be designed to harvest the lentil plants with minimum damage. This mechanism should be evaluated under different tests of crop and machines such as forward speed (FS, grain moisture content (GMC, different varieties and other parameters. Some researchers studied the effects of GMC (Andrews and et al., 1993; Huitink, 2005; Adisa, 2009; Abdi and Jalali, 2013 and FS on grain losses (Geng et al., 1984; Swapan et al., 2001; Mostafavand and Kamgar, 2014; Hunt, 1995. Field tests were conducted at three levels of FS 1.5, 3 and 4.5 km.h-1; three levels of cutting height (CH 4, 8 and 13 cm and two levels of GMC, 8 and 14% on two varieties of lentils including Flip and Shiraz with three replications. Materials and Methods The feeder and cutter mechanism for chickpea harvesting that was the base design of device which is notched wheel and counter shear, was used. The other components of device were dividers, slat and chain feeders, belt and pulleys, chassis, elevator conveyor and storage. Two split plot design based on a randomized complete design was used to determine the effects of above treatments on lentil losses. Results and Discussion The ANOVA results indicated that the all studied factors; FS of feeder and cutter mechanism, CH and GMC had significant effect on losses of Shiraz variety (P0.05. The ranges of losses of Flip variety at 8% GMC were 8.6 to 10% for FS of 1.5 km.h-1, 9.1 to 10.4% for FS of 3 km.h-1and 10.4 to 11.4% for FS of 4.5 km h-1. These ranges at 14% GMC were 7.9 to 8.9% for FS of 1.5 km.h-1, 8.4 to 9.2% for FS of 3 km.h-1and 8.5 to 10% for FS of 4.5 km h-1. The ranges of

  18. Evaluation of the Mechanical Durability of the Egyptian Machine Readable Booklet Passport

    Directory of Open Access Journals (Sweden)

    Ahmed Mahmoud Yosri

    2013-12-01

    Full Text Available In 2008 the first Egyptian booklet Machine Readable Passport/ MRP has been issued and its security and informative standard quality levels were proved in a research published in 2011. Here the durability profiles of the Egyptian MRP have been evaluated. Seven mechanical durability tests were applied on the Egyptian MRP. Such tests are specified in the International Civil Aviation Organization / ICAO standard requirements documents. These seven very severe durability tests resulted in that the Egyptian MRP has achieved better & higher results than the values detected in ICAO-Doc N0232: Durability of Machine Readable Passports - Version: 3.2. Hence, this research had proved the complete conformance between the Egyptian MRP mechanical durability profiles to the international requirements. The Egyptian booklet MRP doesn’t need any obligatory modification concerning its mechanical durability profiles.

  19. Oxidation and Metal-Insertion in Molybdenite Surfaces: Evaluation of Charge-Transfer Mechanisms and Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Ramana, Chintalapalle V.; Becker, U.; Shutthanandan, V.; Julien, C. M.

    2008-06-05

    Molybdenum sulfide (MoS2), an important representative member of the layered transition-metal dichalcogenides, has been of special importance to the research community of geochemistry, materials and environmental chemistry, and industrial science and technology. Understanding the oxidation behavior and charge-transfer mechanisms in MoS2 is important to gain better insight into the degradation of this mineral in the environment. On the other hand understanding the insertion of metals into molybdenite and evaluation of charge-transfer mechanism and dynamics is quite important to utilize these minerals in technological applications. Furthermore, such a detailed investigation of thermal oxidation behavior and intercalation process will provide a basis to further explore and model the mechanism of adsorption of metal ions on to geomedia. Therefore, the present work was performed to understand the oxidation and intercalation processes of molybdenite surfaces. The results obtained, using a wide variety of analytical techniques, are presented and discussed in this paper.

  20. Performance assessment of semiempirical molecular orbital methods in describing halogen bonding: quantum mechanical and quantum mechanical/molecular mechanical-molecular dynamics study.

    Science.gov (United States)

    Ibrahim, Mahmoud A A

    2011-10-24

    The performance of semiempirical molecular-orbital methods--MNDO, MNDO-d, AM1, RM1, PM3 and PM6--in describing halogen bonding was evaluated, and the results were compared with molecular mechanical (MM) and quantum mechanical (QM) data. Three types of performance were assessed: (1) geometrical optimizations and binding energy calculations for 27 halogen-containing molecules complexed with various Lewis bases (Two of the tested methods, AM1 and RM1, gave results that agree with the QM data.); (2) charge distribution calculations for halobenzene molecules, determined by calculating the solvation free energies of the molecules relative to benzene in explicit and implicit generalized Born (GB) solvents (None of the methods gave results that agree with the experimental data.); and (3) appropriateness of the semiempirical methods in the hybrid quantum-mechanical/molecular-mechanical (QM/MM) scheme, investigated by studying the molecular inhibition of CK2 protein by eight halobenzimidazole and -benzotriazole derivatives using hybrid QM/MM molecular-dynamics (MD) simulations with the inhibitor described at the QM level by the AM1 method and the rest of the system described at the MM level. The pure MM approach with inclusion of an extra point of positive charge on the halogen atom approach gave better results than the hybrid QM/MM approach involving the AM1 method. Also, in comparison with the pure MM-GBSA (generalized Born surface area) binding energies and experimental data, the calculated QM/MM-GBSA binding energies of the inhibitors were improved by replacing the G(GB,QM/MM) solvation term with the corresponding G(GB,MM) term.

  1. The Study of Pulmonary Complication of Neonatal Mechanical Ventilation in NICU

    Directory of Open Access Journals (Sweden)

    M.K. Sabzeie

    2016-01-01

    Full Text Available Introduction & Objective: The main indication of mechanical ventilation is in the treatment of neonates with respiratory failure. With the increased use of mechanical ventilation, its complications have increased too. The aim of this study was to evaluate the prevalence of complications and short-term improvement in infants undergoing mechanical ventilation in the neonatal intensive care unit (NICU. Materials & Methods: In this prospective-analytic study, all infants requiring mechanical ventilation and admitted in the neonatal intensive care unit of Fatemiyeh and Be’sat hospitals, have been evaluated for one year (2012. Their data included: neonatal age, sex, gestational age, birth weight, weight at admission, diagnosis, length of hospitalization, disease outcome (improvement-died, need for mechanical ventilation, complications and culture results (blood, endotracheal tube, urine, CSF insert in check list. The data were analysed by SPSS and c2 statistical test. Results: In this study, a total of 114 infants hospitalized in intensive care unit and needed mechanical ventilation was studied of whom 72 were male and 42 were female. The mean of gestational age in the admitted neonates was 32.9 ± 0.85 weeks. The majority of neonates (80.70% were undergoing mechanical ventilation with respiratory distress syndrome (RDS. 67% of neonates were suffering from complications of mechanical ventilation. The prevalent complication was seen in the neonates was narrowing or obstruction of the endotracheal tube (52.63%. 47.37% of infants died and respiratory distress syndrome was the common cause of death in these neonates (46.29%. In our study, there was significant relationship between resuscitation at birth (P=0.002, time required for mechanical ventilation (P=0.0000 and Apgar score (P=0.0000 and complications of mechanical ventilation. Conclusions: The results show that the high prevalence of pulmonary complications is associated with mechanical

  2. The corrosion and corrosion mechanical properties evaluation for the LBB concept in VVERs

    Energy Technology Data Exchange (ETDEWEB)

    Ruscak, M.; Chvatal, P.; Karnik, D.

    1997-04-01

    One of the conditions required for Leak Before Break application is the verification that the influence of corrosion environment on the material of the component can be neglected. Both the general corrosion and/or the initiation and, growth of corrosion-mechanical cracks must not cause the degradation. The primary piping in the VVER nuclear power plant is made from austenitic steels (VVER 440) and low alloy steels protected with the austenitic cladding (VVER 1000). Inspection of the base metal and heterogeneous weldments from the VVER 440 showed that the crack growth rates are below 10 m/s if a low oxygen level is kept in the primary environment. No intergranular cracking was observed in low and high oxygen water after any type of testing, with constant or periodic loading. In the framework of the LBB assessment of the VVER 1000, the corrosion and corrosion mechanical properties were also evaluated. The corrosion and corrosion mechanical testing was oriented predominantly to three types of tests: stress corrosion cracking tests corrosion fatigue tests evaluation of the resistance against corrosion damage. In this paper, the methods used for these tests are described and the materials are compared from the point of view of response on static and periodic mechanical stress on the low alloyed steel 10GN2WA and weld metal exposed in the primary circuit environment. The slow strain rate tests and static loading of both C-rings and CT specimens were performed in order to assess the stress corrosion cracking characteristics. Cyclic loading of CT specimens was done to evaluate the kinetics of the crack growth under periodical loading. Results are shown to illustrate the approaches used. The data obtained were evaluated also from the point of view of comparison of the influence of different structure on the stress corrosion cracking appearance. The results obtained for the base metal and weld metal of the piping are presented here.

  3. Mechanical properties of jennite: A theoretical and experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Juhyuk, E-mail: juhyuk.moon@stonybrook.edu [Civil Engineering Program, Department of Mechanical Engineering, Stony Brook University, NY 11794 (United States); Yoon, Seyoon [School of Engineering, Kings College, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom); Monteiro, Paulo J.M. [Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States)

    2015-05-15

    The objective of this study is to determine the mechanical properties of jennite. To date, several hypotheses have been proposed to predict the structural properties of jennite. For the first time as reported herein, the isothermal bulk modulus of jennite was measured experimentally. Synchrotron-based high-pressure x-ray diffraction experiments were performed to observe the variation of lattice parameters under pressure. First-principles calculations were applied to compare with the experimental results and predict additional structural properties. Accurately measured isothermal bulk modulus herein (K{sub 0} = 64(2) GPa) and the statistical assessment on experimental and theoretical results suggest reliable mechanical properties of shear and Young's modulus, Poisson's ratio, and elastic tensor coefficients. Determination of these fundamental structural properties is the first step toward greater understanding of calcium–silicate–hydrate, as well as provides a sound foundation for forthcoming atomic level simulations.

  4. An evolutionary framework for studying mechanisms of social behavior.

    Science.gov (United States)

    Hofmann, Hans A; Beery, Annaliese K; Blumstein, Daniel T; Couzin, Iain D; Earley, Ryan L; Hayes, Loren D; Hurd, Peter L; Lacey, Eileen A; Phelps, Steven M; Solomon, Nancy G; Taborsky, Michael; Young, Larry J; Rubenstein, Dustin R

    2014-10-01

    Social interactions are central to most animals and have a fundamental impact upon the phenotype of an individual. Social behavior (social interactions among conspecifics) represents a central challenge to the integration of the functional and mechanistic bases of complex behavior. Traditionally, studies of proximate and ultimate elements of social behavior have been conducted by distinct groups of researchers, with little communication across perceived disciplinary boundaries. However, recent technological advances, coupled with increased recognition of the substantial variation in mechanisms underlying social interactions, should compel investigators from divergent disciplines to pursue more integrative analyses of social behavior. We propose an integrative conceptual framework intended to guide researchers towards a comprehensive understanding of the evolution and maintenance of mechanisms governing variation in sociality. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Beer Clarification with polysulfone membrane and study on fouling mechanism

    Directory of Open Access Journals (Sweden)

    Ricardo Cardoso de Oliveira

    2011-12-01

    Full Text Available The aims of the present work were to study the relationship between the fluxes, permeate quality, and fouling mechanism. A polysulfone membrane with 100 KDa and 0.12 m² of surface area was used. Permeate fluxes were measured for different pressures (0.5, 1.0, 1.5, and 2.0 bar at the same temperature of 8 ºC. The fluxes measured for each pressure ranged from 22, 24, 27 and 30 kg h-1m-2 at 0.5, 1.0, 1.5 and 2.0 bar, respectively. Samples of the feed and permeate were analyzed for pH, color, turbidity, sugar, bitterness, and proteins. The fouling mechanisms observed were cake filtration, partial pore blocking, and complete pore blocking.

  6. Study on dynamic lifting characteristics of control rod drive mechanism

    International Nuclear Information System (INIS)

    Shen Xiaoyao

    2012-01-01

    Based on the equations of the electric circuit and the magnetic circuit and analysis of the dynamic lifting process for the control rod drive mechanism (CRDM), coupled magnetic-electric-mechanical equations both for the static status and the dynamic status are derived. The analytical method is utilized to obtain the current and the time when the lift starts. The numerical simulation method of dynamic analysis recommended by ASME Code is utilized to simulate the dynamic lifting process of CRDM, and the dynamic features of the system with different design gaps are studied. Conclusions are drawn as: (1) the lifting-start time increases with the design gap, and the time for the lifting process is longer with larger gaps; (2) the lifting velocity increases with time; (3) the lifting acceleration increases with time, and with smaller gaps, the impact acceleration is larger. (author)

  7. Study on Mechanical Properties of Hybrid Fiber Reinforced Concrete

    Science.gov (United States)

    He, Dongqing; Wu, Min; Jie, Pengyu

    2017-12-01

    Several common high elastic modulus fibers (steel fibers, basalt fibers, polyvinyl alcohol fibers) and low elastic modulus fibers (polypropylene fiber) are incorporated into the concrete, and its cube compressive strength, splitting tensile strength and flexural strength are studied. The test result and analysis demonstrate that single fiber and hybrid fiber will improve the integrity of the concrete at failure. The mechanical properties of hybrid steel fiber-polypropylene fiber reinforced concrete are excellent, and the cube compressive strength, splitting tensile strength and flexural strength respectively increase than plain concrete by 6.4%, 3.7%, 11.4%. Doped single basalt fiber or polypropylene fiber and basalt fibers hybrid has little effect on the mechanical properties of concrete. Polyvinyl alcohol fiber and polypropylene fiber hybrid exhibit ‘negative confounding effect’ on concrete, its splitting tensile and flexural strength respectively are reduced by 17.8% and 12.9% than the single-doped polyvinyl alcohol fiber concrete.

  8. Evaluation of mechanical strength of the joints in JT-60 toroidal field coil conductors

    International Nuclear Information System (INIS)

    Nishio, Satoshi; Ohkubo, Monoru; Sasajima, Hiroshi

    1980-04-01

    Toroidal field (TF) coils of JT-60 produce a toroidal field of 45 kG at a plasma axis, they have an inner bore of 3.90 m and a weight of about 80 metric tons per coil. Eighteen TF coils are located around a torus axis at regular intervals. TF coil conductors are mostly jointed by high frequency induction brazing, the rest jointed by welding. In deciding the details of the jointing procedures, the conductor size and the requested mechanical strength are mainly taken into consideration. Described are non-destructive inspection methods for the brazed joints, strength evaluation, and the inspection criteria. Ultrasonic testing method is found to be the most effective in evaluation of mechanical properties of the brazed joints especially in terms of fatigue strength. In section 1, specifications of the TF coils are given. In section 2, the ultrasonic inspection method and the detectability of this apparatus are described in detail, the defects of known size are compared with the indication values and display figures. The apparatus developed for JT-60 is operated automatically also recording the inspectionresults. In section 3, mechanical strength of the brazed joints with initial defects is discussed on the basis of Fracture Mechanics theory and results of the fatigue crack growth test. The inspection criteria in accordance with the descriptions of section 2 and 3 are given in section 4. (author)

  9. Studies on sulfate attack: Mechanisms, test methods, and modeling

    Science.gov (United States)

    Santhanam, Manu

    The objective of this research study was to investigate various issues pertaining to the mechanism, testing methods, and modeling of sulfate attack in concrete. The study was divided into the following segments: (1) effect of gypsum formation on the expansion of mortars, (2) attack by the magnesium ion, (3) sulfate attack in the presence of chloride ions---differentiating seawater and groundwater attack, (4) use of admixtures to mitigate sulfate attack---entrained air, sodium citrate, silica fume, and metakaolin, (5) effects of temperature and concentration of the attack solution, (6) development of new test methods using concrete specimens, and (7) modeling of the sulfate attack phenomenon. Mortar specimens using portland cement (PC) and tricalcium silicate (C 3S), with or without mineral admixtures, were prepared and immersed in different sulfate solutions. In addition to this, portland cement concrete specimens were also prepared and subjected to complete and partial immersion in sulfate solutions. Physical measurements, chemical analyses and microstructural studies were performed periodically on the specimens. Gypsum formation was seen to cause expansion of the C3S mortar specimens. Statistical analyses of the data also indicated that the quantity of gypsum was the most significant factor controlling the expansion of mortar bars. The attack by magnesium ion was found to drive the reaction towards the formation of brucite. Decalcification of the C-S-H and its subsequent conversion to the non-cementitious M-S-H was identified as the mechanism of destruction in magnesium sulfate attack. Mineral admixtures were beneficial in combating sodium sulfate attack, while reducing the resistance to magnesium sulfate attack. Air entrainment did not change the measured physical properties, but reduced the visible distress of the mortars. Sodium citrate caused a substantial reduction in the rate of damage of the mortars due to its retarding effect. Temperature and

  10. GABAergic Mechanisms in Schizophrenia: Linking Postmortem and In Vivo Studies

    Science.gov (United States)

    de Jonge, Jeroen C.; Vinkers, Christiaan H.; Hulshoff Pol, Hilleke E.; Marsman, Anouk

    2017-01-01

    Schizophrenia is a psychiatric disorder characterized by hallucinations, delusions, disorganized thinking, and impairments in cognitive functioning. Evidence from postmortem studies suggests that alterations in cortical γ-aminobutyric acid (GABAergic) neurons contribute to the clinical features of schizophrenia. In vivo measurement of brain GABA levels using magnetic resonance spectroscopy (MRS) offers the possibility to provide more insight into the relationship between problems in GABAergic neurotransmission and clinical symptoms of schizophrenia patients. This study reviews and links alterations in the GABA system in postmortem studies, animal models, and human studies in schizophrenia. Converging evidence implicates alterations in both presynaptic and postsynaptic components of GABAergic neurotransmission in schizophrenia, and GABA may thus play an important role in the pathophysiology of schizophrenia. MRS studies can provide direct insight into the GABAergic mechanisms underlying the development of schizophrenia as well as changes during its course. PMID:28848455

  11. GABAergic Mechanisms in Schizophrenia: Linking Postmortem and In Vivo Studies

    Directory of Open Access Journals (Sweden)

    Jeroen C. de Jonge

    2017-08-01

    Full Text Available Schizophrenia is a psychiatric disorder characterized by hallucinations, delusions, disorganized thinking, and impairments in cognitive functioning. Evidence from postmortem studies suggests that alterations in cortical γ-aminobutyric acid (GABAergic neurons contribute to the clinical features of schizophrenia. In vivo measurement of brain GABA levels using magnetic resonance spectroscopy (MRS offers the possibility to provide more insight into the relationship between problems in GABAergic neurotransmission and clinical symptoms of schizophrenia patients. This study reviews and links alterations in the GABA system in postmortem studies, animal models, and human studies in schizophrenia. Converging evidence implicates alterations in both presynaptic and postsynaptic components of GABAergic neurotransmission in schizophrenia, and GABA may thus play an important role in the pathophysiology of schizophrenia. MRS studies can provide direct insight into the GABAergic mechanisms underlying the development of schizophrenia as well as changes during its course.

  12. The thermal and mechanical deformation study of up-stream pumping mechanical seal

    International Nuclear Information System (INIS)

    Chen, H L; Xu, C; Zuo, M Z; Wu, Q B

    2015-01-01

    Taking the viscosity-temperature relationship of the fluid film into consideration, a 3-D numerical model was established by ANSYS software which can simulate the heat transfer between the upstream pumping mechanical seal stationary and rotational rings and the fluid film between them as well as simulate the thermal deformation, structure deformation and the coupling deformation of them. According to the calculation result, thermal deformation causes the seal face expansion and the maximum thermal deformation appears at the inside of the seal ring. Pressure results in a mechanical deformation, the maximum deformation occurs at the top of the spiral groove and the overall trend is inward the mating face, opposite to the thermal deformation. The coupling deformation indicate that the thermal deformation can be partly counteracted by pressure deformation. Using this model, the relationship between deformation and shaft speed and the sealing liquid pressure was studied. It's found that the shaft speed will both enhance the thermal and structure deformation and the fluid pressure will enhance the structure deformation but has little to do with the thermal deformation. By changing the sealing material, it's found that material with low thermal expansion coefficient and low elastic modulus will suffer less thermal-pressure deformation

  13. The thermal and mechanical deformation study of up-stream pumping mechanical seal

    Science.gov (United States)

    Chen, H. L.; Xu, C.; Zuo, M. Z.; Wu, Q. B.

    2015-01-01

    Taking the viscosity-temperature relationship of the fluid film into consideration, a 3-D numerical model was established by ANSYS software which can simulate the heat transfer between the upstream pumping mechanical seal stationary and rotational rings and the fluid film between them as well as simulate the thermal deformation, structure deformation and the coupling deformation of them. According to the calculation result, thermal deformation causes the seal face expansion and the maximum thermal deformation appears at the inside of the seal ring. Pressure results in a mechanical deformation, the maximum deformation occurs at the top of the spiral groove and the overall trend is inward the mating face, opposite to the thermal deformation. The coupling deformation indicate that the thermal deformation can be partly counteracted by pressure deformation. Using this model, the relationship between deformation and shaft speed and the sealing liquid pressure was studied. It's found that the shaft speed will both enhance the thermal and structure deformation and the fluid pressure will enhance the structure deformation but has little to do with the thermal deformation. By changing the sealing material, it's found that material with low thermal expansion coefficient and low elastic modulus will suffer less thermal-pressure deformation.

  14. Study of system safety evaluation on LTO of national project. Thermal fatigue evaluation of piping systems

    International Nuclear Information System (INIS)

    Kasahara, Naoto; Itoh, Takamoto; Okazaki, Masakazu; Okuda, Yukihiko; Kamaya, Masayuki; Nakamura, Akira; Nakamura, Hitoshi; Machida, Hideo

    2012-01-01

    Nuclear piping has various kinds of thermal fatigue failure modes. Main causes of thermal loads are structural responses to fluid temperature changes during plant operation. These phenomena have complex mechanisms and so many patterns, that their problems still occur even though well-known issues. To prevent thermal fatigue due to above thermal loads, the JSME guideline is adopted. Both thermal load and fatigue failure mechanism have been investigated and summarized into the knowledgebase. Numerical simulation methods for thermal fatigue evaluation were studied to replace structural tests. Theses knowledge was utilized to validate and justify the JSME guideline. Furthermore, new studies have been launched to apply above knowledge to enhance plant system safety. (author)

  15. Evaluation of mechanical and morphologic features of PLLA membranes as supports for perfusion cells culture systems

    Energy Technology Data Exchange (ETDEWEB)

    Montesanto, S., E-mail: salvatore.montesanto1985@gmail.com [Department of Civil, Environmental, Aerospace, Materials Engineering (DICAM), University of Palermo, Viale delle Scienze Ed. 8, 90128 Palermo (Italy); Brucato, V. [Department of Civil, Environmental, Aerospace, Materials Engineering (DICAM), University of Palermo, Viale delle Scienze Ed. 8, 90128 Palermo (Italy); La Carrubba, V. [Department of Civil, Environmental, Aerospace, Materials Engineering (DICAM), University of Palermo, Viale delle Scienze Ed. 8, 90128 Palermo (Italy); Euro-Mediterranean Institute of Science and Technology (IEMEST), Via Michele Miraglia, 20, 90128 Palermo (Italy)

    2016-12-01

    Porous biodegradable PLLA membranes, which can be used as supports for perfusion cell culture systems were designed, developed and characterized. PLLA membranes were prepared via diffusion induced phase separation (DIPS). A glass slab was coated with a binary PLLA–dioxane solution (8 wt.% PLLA) via dip coating, then pool immersed in two subsequent coagulation baths, and finally dried in a humidity-controlled environment. Surface and mechanical properties were evaluated by measuring pore size, porosity via scanning electron microscopy, storage modulus, loss modulus and loss angle by using a dynamic mechanical analysis (DMA). Cell adhesion assays on different membrane surfaces were also performed by using a standard count method. Results provide new insights into the foaming methods for producing polymeric membranes and supply indications on how to optimise the fabrication parameters to design membranes for tissue cultures and regeneration. - Highlights: • Design, development and characterization of porous biodegradable PLLA membranes via DIPS technology. • Easy-to-tune processing parameters in terms of surface and volumetric properties and cell adhesion. • Evaluation of the impact of the interconnection degree on membrane's mechanical properties. • Evaluation of cell adhesion on different membrane surface textures.

  16. Evaluation of mechanical and morphologic features of PLLA membranes as supports for perfusion cells culture systems

    International Nuclear Information System (INIS)

    Montesanto, S.; Brucato, V.; La Carrubba, V.

    2016-01-01

    Porous biodegradable PLLA membranes, which can be used as supports for perfusion cell culture systems were designed, developed and characterized. PLLA membranes were prepared via diffusion induced phase separation (DIPS). A glass slab was coated with a binary PLLA–dioxane solution (8 wt.% PLLA) via dip coating, then pool immersed in two subsequent coagulation baths, and finally dried in a humidity-controlled environment. Surface and mechanical properties were evaluated by measuring pore size, porosity via scanning electron microscopy, storage modulus, loss modulus and loss angle by using a dynamic mechanical analysis (DMA). Cell adhesion assays on different membrane surfaces were also performed by using a standard count method. Results provide new insights into the foaming methods for producing polymeric membranes and supply indications on how to optimise the fabrication parameters to design membranes for tissue cultures and regeneration. - Highlights: • Design, development and characterization of porous biodegradable PLLA membranes via DIPS technology. • Easy-to-tune processing parameters in terms of surface and volumetric properties and cell adhesion. • Evaluation of the impact of the interconnection degree on membrane's mechanical properties. • Evaluation of cell adhesion on different membrane surface textures.

  17. A Porcine Model for Initial Surge Mechanical Ventilator Assessment and Evaluation of Two Limited Function Ventilators

    Science.gov (United States)

    Dickson, Robert P; Hotchkin, David L; Lamm, Wayne JE; Hinkson, Carl; Pierson, David J; Glenny, Robb W; Rubinson, Lewis

    2013-01-01

    Objective To adapt an animal model of acute lung injury for use as a standard protocol for a screening, initial evaluation of limited function, or “surge,” ventilators for use in mass casualty scenarios. Design Prospective, experimental animal study. Setting University research laboratory. Subjects 12 adult pigs. Interventions 12 spontaneously breathing pigs (6 in each group) were subjected to acute lung injury/acute respiratory distress syndrome (ALI/ARDS) via pulmonary artery infusion of oleic acid. Following development of respiratory failure, animals were mechanically ventilated with a limited function ventilator (Simplified Automatic Ventilator [SAVe] I or II; Automedx) for one hour or until the ventilator could not support the animal. The limited function ventilator was then exchanged for a full function ventilator (Servo 900C; Siemens). Measurements and Main Results Reliable and reproducible levels of ALI/ARDS were induced. The SAVe I was unable to adequately oxygenate 5 animals, with PaO2 (52.0 ± 11.1 torr) compared to the Servo (106.0 ± 25.6 torr; p=0.002). The SAVe II was able to oxygenate and ventilate all 6 animals for one hour with no difference in PaO2 (141.8 ± 169.3 torr) compared to the Servo (158.3 ± 167.7 torr). Conclusions We describe a novel in vivo model of ALI/ARDS that can be used to initially screen limited function ventilators considered for mass respiratory failure stockpiles, and is intended to be combined with additional studies to defintively assess appropriateness for mass respiratory failure. Specifically, during this study we demonstrate that the SAVe I ventilator is unable to provide sufficient gas exchange, while the SAVe II, with several more functions, was able to support the same level of hypoxemic respiratory failure secondary to ALI/ARDS for one hour. PMID:21187747

  18. Elastic-plastic fracture mechanics study of thermal shock cracking

    International Nuclear Information System (INIS)

    Hirano, K.; Kobayashi, H.; Nakazawa, H.

    1980-01-01

    This paper describes thermal shock experiments conducted on a nuclear pressure vessel steel (A533 Grade B Class 1), an AISI304 steel and a tool steel (JIS SKD62) using both a new thermal shock test facility and method. Analysis of their quasi-static thermal stress intensity factors is performed on the basis of linear-elastic fracture mechanics; and a thermal shock fracture toughness value, Ksub(tsc) is evaluated. Then elastic-plastic fracture toughness tests are carried out in the same high temperature range of the thermal shock experiment, and a relation between the stretched zone width, SZW, formed as a result of the fatigue precrack tip plastic blunting and the J-integral is clarified. An elastic-plastic thermal shock fracture toughness value, Jsub(tsc), is evaluated from a critical value of the stretched zone width, SZWsub(tsc), at the initiation of the thermal shock cracking by using the relation between SZW and J. The Jsub(tsc) value is compared with an elastic-plastic fracture toughness value, Jsub(Ic), and the difference between these Jsub(tsc) and Jsub(Ic) values is discussed on the basis of fractography. (author)

  19. Investigation on mechanical properties of basalt composite fabrics (experiment study)

    Science.gov (United States)

    Talebi Mazraehshahi, H.; Zamani, H.

    2010-06-01

    To fully appreciate the role and application of composite materials to structures, correct understanding of mechanical behaviors required for selection of optimum material. Fabric reinforced composites are composed of a matrix that is reinforced with pliable fabric, glass fabric is most popular reinforcement for different application specially in aircraft structure, although other fabric material are also used. At this study new fabric material called basalt with epoxy resin introduced and mechanical behaviors of this material investigated from view point of testing. For this study two type of fabric with different thickness used. Comparison between this composite reinforcement with popular reinforcement as carbon, glass, kevlar performed. To determine mechanical properties of epoxy based basalt fabric following test procedure performed : 1). Tensile testing according to ASTM D3039 in 0° and 90° direction to find ultimate strength in tension and shear, modulus of elasticity, elangation and ultimate strain. 2). Compression testing according to EN 2850 ultimate compression strength and maximum deformation under compression loading. 3). Shear testing according to ASTM D3518-94 to find in plane shear response of polymer matrix composites materials. 4). Predict flexural properties of sandwich construction which manufactured from basalt facing with PVC foam core according to ASTM C393-94. Material strength properties must be based on enough tests of material to meet the test procedure specifications [1]. For this reason six specimens were manufactured for testing and the tests were performed on them using an INSTRON machine model 5582. In the study, the effect of percent of resin in basalt reinforced composite was investigated. Also the weights of the ballast based composites with different percent of resin were measured with conventional composites. As the weight is an important parameter in aerospace industry when the designer wants to replace one material with

  20. Investigation on mechanical properties of basalt composite fabrics (experiment study

    Directory of Open Access Journals (Sweden)

    Talebi Mazraehshahi H.

    2010-06-01

    Full Text Available To fully appreciate the role and application of composite materials to structures, correct understanding of mechanical behaviors required for selection of optimum material. Fabric reinforced composites are composed of a matrix that is reinforced with pliable fabric, glass fabric is most popular reinforcement for different application specially in aircraft structure, although other fabric material are also used. At this study new fabric material called basalt with epoxy resin introduced and mechanical behaviors of this material investigated from view point of testing. For this study two type of fabric with different thickness used. Comparison between this composite reinforcement with popular reinforcement as carbon, glass, kevlar performed. To determine mechanical properties of epoxy based basalt fabric following test procedure performed : 1. Tensile testing according to ASTM D3039 in 0° and 90° direction to find ultimate strength in tension and shear, modulus of elasticity, elangation and ultimate strain. 2. Compression testing according to EN 2850 ultimate compression strength and maximum deformation under compression loading. 3. Shear testing according to ASTM D3518-94 to find in plane shear response of polymer matrix composites materials. 4. Predict flexural properties of sandwich construction which manufactured from basalt facing with PVC foam core according to ASTM C393-94. Material strength properties must be based on enough tests of material to meet the test procedure specifications [1]. For this reason six specimens were manufactured for testing and the tests were performed on them using an INSTRON machine model 5582. In the study, the effect of percent of resin in basalt reinforced composite was investigated. Also the weights of the ballast based composites with different percent of resin were measured with conventional composites. As the weight is an important parameter in aerospace industry when the designer wants to replace one

  1. Mechanical ventilation and volutrauma: study in vivo of a healthy pig model

    Directory of Open Access Journals (Sweden)

    Camilla V Pastore

    2011-01-01

    Full Text Available Mechanical ventilation is essential in intensive care units. However, it may itself induce lung injury. Current studies are based on rodents, using exceptionally large tidal volumes for very short periods, often after a "priming" pulmonary insult. Our study deepens a clinically relevant large animal model, closely resembling human physiology and the ventilator setting used in clinic settings. Our aim was to evaluate the pathophysiological mechanisms involved in alveolo/capillary barrier damage due to mechanical stress in healthy subjects. We randomly divided 18 pigs (sedated with medetomidine/tiletamine-zolazepam and anesthetised with thiopental sodium into three groups (n=6: two were mechanically ventilated (tidal volume of 8 or 20 ml/kg, the third breathed spontaneously for 4 hours, then animals were sacrificed (thiopental overdose. We analyzed every 30' hemogasanalysis and the main circulatory and respiratory parameters. Matrix gelatinase expression was evaluated on bronchoalveolar lavage fluid after surgery and before euthanasia. On autoptic samples we performed zymographic analysis of lung, kidney and liver tissues and histological examination of lung. Results evidenced that high Vt evoked profound alterations of lung mechanics and structure, although low Vt strategy was not devoid of side effects, too. Unexpectedly, also animals that were spontaneously breathing showed a worsening of the respiratory functions.

  2. Hydrodenitrogenation mechanism of aromatic amines. Kinetic study and simulation

    International Nuclear Information System (INIS)

    D'Araujo, P.A.P.

    1994-06-01

    The decomposition of model molecules reacting alone or in competition was studied in a fixed bed reactor at 623 K and 7 MPa over a sulfided NiMo/Al 2 O 3 catalyst. The inhibiting effect of H 2 S and some nitrogen molecules, namely quinoline type compounds plays a major role in the transformation of anilines intermediates. On the other hand H 2 S acts as a cocatalyst and promote carbon-nitrogen bond cleavage, specially at low H 2 S partial pressure. When the H 2 S partial pressure is greater than the nitrogen compound partial pressure an inhibiting effect of H 2 S occurs and its promoting effect on carbon-nitrogen bond cleavage is cancelled. Hydrogen has a positive but moderate effect in hydrogenation steps. The mechanism of carbon-nitrogen bond scission depends on the structure of the nitrogen molecule namely on the hybridization of the carbon atom bearing the nitrogen atom. If the carbon a with respect to the nitrogen is monosubstituted the mechanism is essentially a nucleophilic substitution. When the degree of substitution increases the elimination mechanism becomes more important and the two mechanisms are in competition. With a sulfided catalyst, H 2 S from the gas phase doesn't change the importance of each mechanism, it just increases the rate of the reaction. In the presence of an oxide catalyst the contribution of the two mechanisms change. This result shows the importance of the sulphur species from the surface. Using isotopic exchange we could demonstrate that the sites able to dissociate H 2 S and H 2 are the same, and that the dissociation is of heterolytic nature. The kinetic modeling of hydrotreatment reactions using the CHEMKIN/SURFACE CHEMKIN package seems to be a convenient method in order to understand the kinetic and mechanistic phenomena in hydrodenitrogenation. The preliminary simulations in the case of 2.6 diethylaniline showed that only one type of site is not sufficient in order to account for the experimental results. Further simulations

  3. Study of the mechanisms of matrix assisted laser desorption / ionization

    International Nuclear Information System (INIS)

    Manuelli, Pascal

    1995-01-01

    This research thesis aims at a better knowledge of some aspects of a complex mechanism: the matrix-assisted laser desorption/ionization (MALDI). The author first proposes a comparative analysis of results obtained by time-of-flight (TOF) mass spectrometry and by Fourier transform mass spectrometry. He reports the study of the matrix role (notably a polymeric matrix) as a matter submitted to laser desorption. In this respect, the influence of the incident wavelength has been studied. The author also reports a comparative of ions produced by matrix laser desorption (study performed by Fourier transform mass spectrometry) and of neutral molecules (study performed by flash pyrolysis coupled with gas chromatography and with mass spectrometry). Finally, results obtained on derivatives and complexes based on beta-cyclodextrins highlight benefits as well as limitations of this technique [fr

  4. Study on indium leaching from mechanically activated hard zinc residue

    Directory of Open Access Journals (Sweden)

    Yao J.H.

    2011-01-01

    Full Text Available In this study, changes in physicochemical properties and leachability of indium from mechanically activated hard zinc residue by planetary mill were investigated. The results showed that mechanical activation increased specific surface area, reaction activity of hard zinc residue, and decreased its particle size, which had a positive effect on indium extraction from hard zinc residue in hydrochloric acid solution. Kinetics of indium leaching from unmilled and activated hard zinc residue were also investigated, respectively. It was found that temperature had an obvious effect on indium leaching rate. Two different kinetic models corresponding to reactions which are diffusion controlled, [1-(1- x1/3]2=kt and (1-2x/3-(1-x2/3=kt were used to describe the kinetics of indium leaching from unmilled sample and activated sample, respectively. Their activation energies were determined to be 17.89 kJ/mol (umilled and 11.65 kJ/mol (activated within the temperature range of 30°C to 90°C, which is characteristic for a diffusion controlled process. The values of activation energy demonstrated that the leaching reaction of indium became less sensitive to temperature after hard zinc residue mechanically activated by planetary mill.

  5. Mechanics of Sister Chromatids studied with a Polymer Model

    Directory of Open Access Journals (Sweden)

    Yang eZhang

    2013-10-01

    Full Text Available Sister chromatid cohesion denotes the phenomenon that sister chromatids are initially attached to each other in mitosis to guarantee the error-free distribution into the daughter cells. Cohesion is mediated by binding proteins and only resolved after mitotic chromosome condensation is completed. However, the amount of attachement points required to maintain sister chromatid cohesion while still allowing proper chromosome condensation is not known yet. Additionally the impact of cohesion on the mechanical properties of chromosomes also poses an interesting problem. In this work we study the conformational and mechanical properties of sister chromatids by means of computer simulations. We model both protein-mediated cohesion between sister chromatids and chromosome condensation with a dynamic binding mechanisms. We show in a phase diagram that only specific link concentrations lead to connected and fully condensed chromatids that do not intermingle with each other nor separate due to entropic forces. Furthermore we show that dynamic bonding between chromatids decrease the Young's modulus compared to non-bonded chromatids.

  6. A discrete model to study reaction-diffusion-mechanics systems.

    Science.gov (United States)

    Weise, Louis D; Nash, Martyn P; Panfilov, Alexander V

    2011-01-01

    This article introduces a discrete reaction-diffusion-mechanics (dRDM) model to study the effects of deformation on reaction-diffusion (RD) processes. The dRDM framework employs a FitzHugh-Nagumo type RD model coupled to a mass-lattice model, that undergoes finite deformations. The dRDM model describes a material whose elastic properties are described by a generalized Hooke's law for finite deformations (Seth material). Numerically, the dRDM approach combines a finite difference approach for the RD equations with a Verlet integration scheme for the equations of the mass-lattice system. Using this framework results were reproduced on self-organized pacemaking activity that have been previously found with a continuous RD mechanics model. Mechanisms that determine the period of pacemakers and its dependency on the medium size are identified. Finally it is shown how the drift direction of pacemakers in RDM systems is related to the spatial distribution of deformation and curvature effects.

  7. Numerical and Experimental Study of Mechanisms Involved in Boiling Histotripsy.

    Science.gov (United States)

    Pahk, Ki Joo; Gélat, Pierre; Sinden, David; Dhar, Dipok Kumar; Saffari, Nader

    2017-12-01

    The aim of boiling histotripsy is to mechanically fractionate tissue as an alternative to thermal ablation for therapeutic applications. In general, the shape of a lesion produced by boiling histotripsy is tadpole like, consisting of a head and a tail. Although many studies have demonstrated the efficacy of boiling histotripsy for fractionating solid tumors, the exact mechanisms underpinning this phenomenon are not yet well understood, particularly the interaction of a boiling vapor bubble with incoming incident shockwaves. To investigate the mechanisms involved in boiling histotripsy, a high-speed camera with a passive cavitation detection system was used to observe the dynamics of bubbles produced in optically transparent tissue-mimicking gel phantoms exposed to the field of a 2.0-MHz high-intensity focused ultrasound (HIFU) transducer. We observed that boiling bubbles were generated in a localized heated region and cavitation clouds were subsequently induced ahead of the expanding bubble. This process was repeated with HIFU pulses and eventually resulted in a tadpole-shaped lesion. A simplified numerical model describing the scattering of the incident ultrasound wave by a vapor bubble was developed to help interpret the experimental observations. Together with the numerical results, these observations suggest that the overall size of a lesion induced by boiling histotripsy is dependent on the sizes of (i) the heated region at the HIFU focus and (ii) the backscattered acoustic field by the original vapor bubble. Copyright © 2017 World Federation for Ultrasound in Medicine and Biology. Published by Elsevier Inc. All rights reserved.

  8. A discrete model to study reaction-diffusion-mechanics systems.

    Directory of Open Access Journals (Sweden)

    Louis D Weise

    Full Text Available This article introduces a discrete reaction-diffusion-mechanics (dRDM model to study the effects of deformation on reaction-diffusion (RD processes. The dRDM framework employs a FitzHugh-Nagumo type RD model coupled to a mass-lattice model, that undergoes finite deformations. The dRDM model describes a material whose elastic properties are described by a generalized Hooke's law for finite deformations (Seth material. Numerically, the dRDM approach combines a finite difference approach for the RD equations with a Verlet integration scheme for the equations of the mass-lattice system. Using this framework results were reproduced on self-organized pacemaking activity that have been previously found with a continuous RD mechanics model. Mechanisms that determine the period of pacemakers and its dependency on the medium size are identified. Finally it is shown how the drift direction of pacemakers in RDM systems is related to the spatial distribution of deformation and curvature effects.

  9. Compound antimalarial ethosomal cataplasm: preparation, evaluation, and mechanism of penetration enhancement

    Directory of Open Access Journals (Sweden)

    Shen S

    2015-06-01

    Full Text Available Shuo Shen, Shu-Zhi Liu, Yu-Shi Zhang, Mao-Bo Du, Ai-Hua Liang, Li-Hua Song, Zu-Guang Ye Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, People’s Republic of China Abstract: Malaria is still a serious public health problem in some parts of the world. The problems of recurrence and drug resistance are increasingly more serious. Thus, it is necessary to develop a novel antimalarial agent. The objectives of this study were to construct a novel compound antimalarial transdermal nanosystem–ethosomal cataplasm, to investigate its characteristics and efficiency, and to systematically explore the penetration-enhancing mechanisms of ethosomal cataplasm. Artesunate-loaded ethosomes and febrifugine-loaded ethosomes were prepared, and their characteristics were evaluated. Drug-loaded ethosomes were incorporated in the matrix of cataplasm to form the compound antimalarial ethosomal cataplasm. With the help of ethosomal technology, the accumulated permeation quantity of artesunate significantly increased at 8 hours after administration, which was 1.57 times as much as that of conventional cataplasm. Soon after administration, the ethosomal cataplasm could make a large quantity of antimalarial drug quickly penetrate through skin, then the remaining drug in the ethosomal cataplasm could be steadily released. These characteristics of ethosomal cataplasm are favorable for antimalarial drugs to kill Plasmodium spp. quickly and prevent the resurgence of Plasmodium spp. As expected, the ethosomal cataplasm showed good antimalarial efficiency in this experiment. The negative conversion rates were 100% and the recurrence rates were 0% at all dosages. The mechanism of penetration enhancement of the ethosomal cataplasm was systematically explored using an optics microscope, polarization microscope, and transmission electron microscopy. The microstructure, ultrastructure, and birefringent structure in skin were observed. Data

  10. Mechanical strength evaluation of the welded bellows for the ports of the JT-60 vacuum vessel

    International Nuclear Information System (INIS)

    Takatso, H.; Shimizu, M.; Yamamoto, M.

    1983-01-01

    Mechanical strength of the welded bellows for the ports of the JT-60 vacuum vessel was evaluated, laying the emphasis on the fatigue strength under the torsional electromagnetic force. The welded bellows were designed to be loaded with the forced deflection due to the relative displacement between the vacuum vessel and the external fixed point, the atmospheric pressure and the forced torsional angle due to the electromagnetic force. Stresses caused by the former two were estimated following the formulae proposed by the Kellogg Company. On the other hand, two formulae were established to estimate the stress caused by the last, after examining experimentally the behavior of the welded bellows under the torsional load; one is the shearing stress evaluation formula and the other is the axial bending stress evaluation formula. It was found that the welded bellows can easily buckle under the torsional load and the former formula corresponds to the case of non-buckling and the latter to the case of buckling. The present mechanical strength evaluation method was applied to the three kinds of the welded bellows to be used in the ports of the JT-60 vacuum vessel (neutral beam injection ports, vacuum pumping ports and the adjustable limiter ports) and it was confirmed that they have sufficient strength in the range of the design load conditions

  11. Evaluation of fuel-temperature feedback mechanisms in TRAC-PF1/MOD2/NESTLE

    International Nuclear Information System (INIS)

    Knepper, Paula L.; Feltus, Madeline; Hochreiter, L.E.; Ivanov, Kostadin

    1999-01-01

    Coupled spatial kinetics and thermal-hydraulics system codes provide a means to model transient nuclear reactor behavior more accurately. Transients marked by strong perturbations, both with thermal-hydraulics and neutronics, such as a control-rod ejection or a main steam-line break, are especially of interest. It is now feasible to model complex reactor behavior with a coupled thermal-hydraulics and spatial kinetics code that provides a means to forecast safety margins. Recently, the Transient Reactor Analysis Code (TRAC)-PF1/MOD2, Version 5.4.25, was coupled with the NESTLE code. This coupled code (TRAC-PF1/MOD2/NESTLE) is used to examine effective fuel-temperature models. The Electric Power Research Institute (EPRI) rod-ejection benchmark was analyzed to evaluate the influence of effective fuel temperature. The rod-ejection transient tests only the fuel-rod, heat-conduction coupling. The coolant thermal-hydraulic coupling is not tested because of the speed of the transient. The neutronics solution changes extremely rapidly, whereas the convective heat transfer at the fuel surface requires more time to influence the coolant temperature of the system. The need to model the response of the system coolant temperature is not crucial in this analysis. The influence of the effective fuel temperature is the key component of this study. Various models were examined using the coupled code to calculate effective fuel temperatures. The influence of different, effective fuel-temperature models on the coupled-code results is studied. Three effective fuel-temperature models are examined: (l) volume average effective fuel temperature, (2) the effective fuel-temperature model suggested by the Office of Economic Cooperation and Development (OECD) rod-ejection benchmark, and (3) the NESTLE effective fuel-temperature model. A discussion is provided describing the effective fuel-temperature models examined in TRAC-PF1/MOD2/NESTLE and the influence of effective fuel temperature in

  12. A study on the mechanism and prediction of mine subsidence

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Byung-Chan; Moon, Hyun-Koo [Hanyang University, Seoul(Korea)

    2001-06-30

    The ground subsidence problem due to the increasing number of abandoned coal mines becomes serious. Recently, the sinkhole type subsidence occurred in many abandoned mines has raised an urgent stability question on the nearby railroads, bridges and buildings. But the study on the mechanism of discontinuous subsidence has not attracted much attention in the past. This study is mainly concerned with the mechanism and prediction of mine subsidence. Analyzed and presented in this study are the maximum possible height of roof caving for various shapes of caved zone using bulking factor approach, the critical depth of protective coal seam using the limit equilibrium method, and the factor of safety of stops using the limit equilibrium method with the friction angle and cohesion of rock. As prediction tools the influence function method and the probabilistic method are presented. An empirical equation is obtained from the subsidence data in Chulam and Chungsung areas and applied to Manhang coal mine. The probability of subsidence in Manhang area turned out to be high according to the subsidence frequency of 9.66. (author). 12 refs., 7 tabs., 21 figs.

  13. Study on a mechanical snubber with an adjustment mechanism for resisting force

    International Nuclear Information System (INIS)

    Ohmata, Kenichiro; Miyanaga, Hiroyuki.

    1991-01-01

    The mechanical snubber is an earthquakeproof device for a piping system under particular circumstances such as high temperature and radioactivity. It restrains the piping system by a strong resisting force during an earthquake. This strong force can cause elastic failure of grooves on a brake disk, where steel balls are placed. In this report, an improved mechanical snubber having an adjustment mechanism for resisting force is proposed in order to obtain a mechanical snubber which has almost the same restraint effect and less resisting force in comparison with a conventional mechanical snubber. The resisting force characteristics and the restraint effect of the improved mechanical snubber applied to a simple beam are discussed both numerically and experimentally. The digital simulations are carried out using the Continuous System Simulation Language (CSSL). (author)

  14. Structural mechanics studies at E.D.F

    International Nuclear Information System (INIS)

    Baylac, G.

    1983-01-01

    Structural mechanics studies at EDF have three goals: a better knowledge of the materials properties, an an improvement of the design, and a better in service surveillance of the components. This study has lead EDF to perform a large investment to make possible the fatigue survey of the primary circuit. This investment is of 10 men-years for the mechanical studies. A cumulative bookkeeping of the transients is now in action at Fessenheim I and II, Bugey II to V, Tricastin I, Gravelines I, Dampierre I. A catalog of the transients easy to use will be provided to each unit in the near future. The design of the new four loop plants will take advantage of a new catalog of the design transients, this catalog being used for the purpose of the design and the bookkeeping of the transients. Experimental and theoretical investigations concerning the vibrations of PWR internals and primary circuit have been carried out at Fessenheim I, Bugey V and Tricastin I . As a result of these studies and complementary studies on Safran mock-up, EDF has been able to define with FRAMATOME and CEA a monitoring system to meet the requirements of the safety authorities. The monitoring system is divided in to three parts: loose - parts detection system accelerometers; monitoring of reactor internals by neutron noise measurements; monitoring of heavy components vibrations by accelerometers. This system is now installed in all PWR units. Some developments are in progress at EDF mainly at the Directorate of Research and Development to improve the procedures of the control and to define the criteria for an early diagnostic of the anomalies. The major reports are Surveillance du comportement vibratoire des composants de circuit primaire; Vibration studies on a three loop PWR internals model; and Nuclear Reactor Surveillance - Neutron noise measurements and vibrations analysis on French PWR Internal structures

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-06-01

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

  16. Evaluation of mechanical strength and hydrate products evolution of calcium aluminate cement, for endodontic applications

    International Nuclear Information System (INIS)

    Luz, A.P.; Borba, N.Z.; Pandolfelli, V.C.

    2011-01-01

    Mineral trioxide aggregate (MTA) is the most used retrograde filling cement in the endodontic area. Nevertheless, although its composition is similar to the conventional Portland cement, its high cost, long setting time and low mechanical strength have led to a continuous search for new alternative materials. Considering these aspects, the mechanical strength and crystalline phase evolution of a calcium aluminate cement (CAC), during its hydration process, have been evaluated in this work aiming to apply such material for endodontic treatments. Secar 71 cement samples were prepared and kept in contact with water or SBF (simulated body fluid) during 15 days at 37 deg C. Compressive strength, apparent porosity, X ray diffraction and thermogravimetric tests were carried out for the samples evaluation after 1, 3, 7 and 15 days. The main identified phases were CAH_1_0, C_2AH_8, C_3AH_6 and AH_3. Moreover, when in the presence of SBF, some changes in the amount of the hydrates in the CAC samples were observed, which affected the mechanical behavior of the cement. (author)

  17. Evaluation of mechanical design fire brick at test section on the HeaTiNG-02

    International Nuclear Information System (INIS)

    Dedy Haryanto; Riswan Djambiar; Sagino; Edy Sumarno

    2013-01-01

    The activity was carried out due to the modification of the heating in the HeaTiNG-02 test section. Modification of the heater needs to be done to overcome the obstacles that arise as part of the test section is used. Constraint that often arises is the fall of the heating source with super khantal material when it reaches a certain temperature. To mitigate the super khantal position is initially converted into a vertical position horizontal. The change from vertical to horizontal position on super khantal cause any deformities in refractory fire brick which serves as a support super khantal. Manufacture of refractory design fire brick formation and mechanical strength evaluation performed using CATIA V5 R20 software. Evaluation of fireproof rock mechanics to be based on the mechanical properties of alumina as a refractory material of fire brick. The results of the analysis have a fire brick design stress greater than the bend strength alumina materials, so that the necessary checks before and after the experiment as well as the replacement of refractory fire brick if something is broken. Translational greatest displacement 0.453 mm at a temperature of 1575 K did not give any meaningful form. Thus the refractory fire brick design can be used as heating source support in the HeaTiNG-02 test section with checks before and after the operation. (author)

  18. Study of the ionizing radiation effect on the polyamide 6,6 mechanical properties

    International Nuclear Information System (INIS)

    Colombo, Maria Aparecida da Silva

    2004-01-01

    Polyamide 6,6 due to its excellent mechanical, thermal and electrical properties and its great performance in multiple industrial applications is considered one of the most important engineering polymers. However, in specific applications, some of its properties need to be improved by means additives or fillers to reach the required properties increasing its final cost. By these considerations, the aim of this work was to apply the ionizing radiation to improve the natural mechanical properties of polyamide 6,6. Also, to evaluate the irradiation parameters, and the mechanical performance of the irradiated polymer in order to use the cross-linking, induced by ionizing radiation, as substitute of additives and fillers. Row polyamide 6,6 samples, for mechanical tests, were prepared by injection molded and then irradiated with high energetic electrons to reach doses of 70, 100, 150, and 200 kGy. The mechanical performance, of non-irradiated and irradiated samples, was evaluated by tensile strength, impact, hardness and wear measurements. Furthermore, hardness and wear tests were carried out with samples, which were immersed in petroleum and sea water for 6 months. The experimental results have shown that, in the studied dose range, the tensile strength increases 25%, the hardness Shore D 15%, the impact values diminished by 80% and the wear values decreased 20 times between 0 and 200 kGy. The effect of the petroleum and sea water were shown mainly in the nonirradiated samples. (author)

  19. Evaluation of roentgenologic study of the stomach

    International Nuclear Information System (INIS)

    Suh, Jung Ho; Choi, Byung So

    1972-01-01

    In order to achieve more correct diagnosis of gastric lesion, further progress in the technique of diagnosis is much desired. And so, in pursuing the more ideal study, about 7,500 cases of U. G. I. studies taken in Severance Hospital in the past 29 months from May 1969 to September 1971, have been reviewed to evaluate how the following factors will affect the demonstrability of gastric lesion in upper G. I. series. (1) Introduction of air into the stomach by nasogastric tube. (2) Kinds and concentration of barium. (3) Demonstrability according to the position of the patient. (4) Use of antispasmodics. The results may be briefly summarized as follows: 1. The intubation of nasogastric tube gives discomfort temporarily to the patient: however, it has an advantage that the amount of air required for ideal insufflation of the stomach can be controlled under the fluoroscopy. 2. About concentration and type of barium. a) Mikabarium in 90% seems to give the best result in filling study, mucosal relief study and double contrast study. b) Mikabarium in higher concentration adheres to the mucosa better, thus resulting in good double contrast: however, it tends to coagulate each other in the high concentration. c) Micropaque powder of 110% solution produces good double contrast, but it has the disadvantage of making air bubbles. d) When water is given prior to barium ingestion, the anterior wall of stomach is better demonstrated with mucosal relief study. e) To get better result in contrast study, the selection of barium is important as well as rapid and proper positioning of the patient and abdominal respiratory movement. 3. Demonstrability of the stomach lesion according to the position. a) The small lesion either in pylorus or in antrum can be best demonstrated by compression technique of double contrast method in supine position. b) The mucosal relief study in prone by adequate air insufflation was proper to demonstrate the lesion of anterior wall. c) In the lesion of the

  20. Nanobioceramic Composites: A Study of Mechanical, Morphological, and Thermal Properties

    Directory of Open Access Journals (Sweden)

    Sivabalan Sasthiryar

    2013-12-01

    Full Text Available The aim of this study was to explore the incorporation of biomass carbon nanofillers (CNF into advanced ceramic. Biomass from bamboo, bagasse (remains of sugarcane after pressing, and oil palm ash was used as the predecessor for producing carbon black nanofillers. Furnace pyrolysis was carried out at 1000 °C and was followed by ball-mill processing to obtain carbon nanofillers in the range of 50 nm to 100 nm. CNFs were added to alumina in varying weight fractions and the resulting mixture was subjected to vacuum sintering at 1400 °C to produce nanobioceramic composites. The ceramic composites were characterized for mechanical, thermal, and morphological properties. A high-resolution Charge-coupled device (CCD camera was used to study the fracture impact and the failure mechanism. An increase in the loading percentage of CNFs in the alumna decreased the specific gravity, vickers hardness (HV, and fracture toughness values of the composite materials. Furthermore, the thermal conductivity and the thermal stability of the ceramic composite increased as compared to the pristine alumina.

  1. Elements of Motivational Structure for Studying Mechanical Engineering

    Directory of Open Access Journals (Sweden)

    Nikša Dubreta

    2017-12-01

    Full Text Available The article presents the findings on students' reasons for studying mechanical engineering. These reasons were covered in terms of extrinsic and intrinsic motivation additionally related to selected independent variables of the sample – students' secondary school Grade Point Average, their gender and the socio-economic status. The research was conducted with the first year students of the Faculty of Mechanical Engineering at the University of Zagreb, Croatia. The sample consisted of 282 students (228 males and 54 females and comprised students of all majors. According to descriptive character of the questionnaire type survey characteristics of the sample are presented. Composite variables of extrinsic and intrinsic motivation were dichotomized to present different levels of the students' overall motivational structure. Results indicate a students' interest in the field of science and technology as the most important element of intrinsic motivation, with no significant relation to any of independent variables. By contrast, extrinsic motivation has manifested as significantly related to the variables of Grade Point Average and to parents' education as one component of the socio-economic status. However, a significant level of indecisive respondents regarding the both intrinsic and extrinsic motivation suggests that the choice of the study programme is not always a consistent and an unambiguous process.

  2. Mechanical and Tribological Properties of PVD-Coated Cemented Carbide as Evaluated by a New Multipass Scratch-Testing Method

    Directory of Open Access Journals (Sweden)

    M. Fallqvist

    2012-01-01

    Full Text Available A new test method based on multipass scratch testing has been developed for evaluating the mechanical and tribological properties of thin, hard coatings. The proposed test method uses a pin-on-disc tribometer and during testing a Rockwell C diamond stylus is used as the “pin” and loaded against the rotating coated sample. The influence of normal load on the number of cycles to coating damage is investigated and the resulting coating damage mechanisms are evaluated by posttest scanning electron microscopy. The present study presents the test method by evaluating the performance of Ti0.86Si0.14N, Ti0.34Al0.66N, and (Al0.7Cr0.32O3 coatings deposited by cathodic arc evaporation on cemented carbide inserts. The results show that the test method is quick, simple, and reproducible and can preferably be used to obtain relevant data concerning the fatigue, wear, chipping, and spalling characteristics of different coating-substrate composites. The test method can be used as a virtually nondestructive test and, for example, be used to evaluate the fatigue and wear resistance as well as the cohesive and adhesive interfacial strength of coated cemented carbide inserts prior to cutting tests.

  3. Mechanics

    CERN Document Server

    Chester, W

    1979-01-01

    When I began to write this book, I originally had in mind the needs of university students in their first year. May aim was to keep the mathematics simple. No advanced techniques are used and there are no complicated applications. The emphasis is on an understanding of the basic ideas and problems which require expertise but do not contribute to this understanding are not discussed. How­ ever, the presentation is more sophisticated than might be considered appropri­ ate for someone with no previous knowledge of the subject so that, although it is developed from the beginning, some previous acquaintance with the elements of the subject would be an advantage. In addition, some familiarity with element­ ary calculus is assumed but not with the elementary theory of differential equations, although knowledge of the latter would again be an advantage. It is my opinion that mechanics is best introduced through the motion of a particle, with rigid body problems left until the subject is more fully developed. Howev...

  4. Autogenous shrinkage in high-performance cement paste: An evaluation of basic mechanisms

    International Nuclear Information System (INIS)

    Lura, Pietro; Jensen, Ole Mejlhede; Breugel, Klaas van

    2003-01-01

    In this paper, various mechanisms suggested to cause autogenous shrinkage are presented. The mechanisms are evaluated from the point of view of their soundness and applicability to quantitative modeling of autogenous shrinkage. The capillary tension approach is advantageous, because it has a sound mechanical and thermodynamical basis. Furthermore, this mechanism is easily applicable in a numerical model when dealing with a continuously changing microstructure. In order to test the numerical model, autogenous deformation and internal relative humidity (RH) of a Portland cement paste were measured during the first week of hardening. The isothermal heat evolution was also recorded to monitor the progress of hydration and the elastic modulus in compression was measured. RH change, degree of hydration and elastic modulus were used as input data for the calculation of autogenous deformation based on the capillary tension approach. Because a part of the RH drop in the cement paste is due to dissolved salts in the pore solution, a method is suggested to separate this effect from self-desiccation and to calculate the actual stress in the pore fluid associated with menisci formation

  5. Evaluation of mechanical properties and durability performance of HDPE-wood composites

    International Nuclear Information System (INIS)

    Tazi, M.; Erchiqui, F.; Kaddami, H.; Bouazara, M.; Poaty, B.

    2015-01-01

    The objective of this work is to evaluate the mechanical properties and durability performance of bio-composite materials made from sawdust and thermoplastic polymer (HDPE). For the preparation of the composites, sawdust in different proportions with Maleic Anhydride grafted Polyethylene (MAPE) as the coupling agent was used. The thermal and mechanical properties were successively characterized. The results indicate that adding wood fillers to a polymer matrix increases the degree of crystallinity and improves the tensile strength and ductility of composites. On the contrary, resistance to water absorption decreases as a function of the wood fillers. Scanning electron microscopy (SEM) was used to analyze morphological structure alteration when exposed to intense weathering. The biodegradability of bio-composites up to 97 days was also investigated; the results indicate that, by increasing the filler content, the amount of weight loss increased as well. In other words, even though the addition of sawdust to thermoplastic polymer improves the mechanical performance of a composite material, it also accelerates the biodegradation rate of the composite. An optimum amount of filler content might compromise the effect of biodegradation and mechanical properties of composite materials

  6. Evaluation of mechanical properties and durability performance of HDPE-wood composites

    Energy Technology Data Exchange (ETDEWEB)

    Tazi, M.; Erchiqui, F. [Engineering department, Université de Quebec en Abitibi-Témiscamingue (Canada); Kaddami, H. [Université Caddi Ayad Marrakech, Laboratoire ’LCO2MC’, B.P. 549, Marrakech 40000, Maroc (Morocco); Bouazara, M. [Mechanical department, Université de Québec à Chicoutimi Canada (Canada); Poaty, B. [Technology Center of industrial residuals, QC Canada (Canada)

    2015-05-22

    The objective of this work is to evaluate the mechanical properties and durability performance of bio-composite materials made from sawdust and thermoplastic polymer (HDPE). For the preparation of the composites, sawdust in different proportions with Maleic Anhydride grafted Polyethylene (MAPE) as the coupling agent was used. The thermal and mechanical properties were successively characterized. The results indicate that adding wood fillers to a polymer matrix increases the degree of crystallinity and improves the tensile strength and ductility of composites. On the contrary, resistance to water absorption decreases as a function of the wood fillers. Scanning electron microscopy (SEM) was used to analyze morphological structure alteration when exposed to intense weathering. The biodegradability of bio-composites up to 97 days was also investigated; the results indicate that, by increasing the filler content, the amount of weight loss increased as well. In other words, even though the addition of sawdust to thermoplastic polymer improves the mechanical performance of a composite material, it also accelerates the biodegradation rate of the composite. An optimum amount of filler content might compromise the effect of biodegradation and mechanical properties of composite materials.

  7. Examination of constitutive model for evaluating long-term mechanical behavior of buffer. 3

    International Nuclear Information System (INIS)

    Takaji, Kazuhiko; Shigeno, Yoshimasa; Shimogouchi, Takafumi; Shiratake, Toshikazu; Tamura, Hirokuni

    2004-02-01

    On the R and D of the high-level radioactive waste repository, it is essential that Engineered Barrier System (EBS) is stable mechanically over a long period of time for maintaining each ability required to EBS. After closing the repository, the various external forces will be affected to buffer intricately for a long period of time. So, to make clear the mechanical deformation behavior of buffer against the external force is important, because of carrying out safety assessment of EBS accurately. In this report, several sets of parameters are chosen for the previously selected two constitutive models, Sekiguchi-Ohta model and Adachi-Oka model, and the element tests and mock-up tests are simulated using these parameters. Through the simulation, applicability of the constitutive models and parameters is examined. Moreover, simulation analyses of EBS using these parameters is examined. Moreover, simulation analyses of EBS using these parameters were carried out, and mechanical behavior is evaluated over a long period of time. Analysis estimated the amount of settlement of the over pack, the stress state of buffer material, the reaction force to a base rock, etc., and the result that EBS is mechanically stable over a long period of time was obtained. Next, in order to prove analyses results a side, literature survey was conducted about geological age, the dynamics history of a Smectite layer. The outline plan was drawn up about the natural analogue verification method and preliminary examination was performed about the applicability of Freezing Sampling'. (author)

  8. Study of anisotropic mechanical properties for aeronautical PMMA

    Directory of Open Access Journals (Sweden)

    Wei Shang

    Full Text Available For the properties of polymer are relative to its structure, the main purpose of the present work is to investigate the mechanical properties of the aeronautical PMMA which has been treated by the directional tensile technology. Isodyne images reveal the stress state in directional PMMA. And then, an anisotropic mechanical model is established. Furthermore, all mechanical parameters are measured by the digital image correlation method. Finally, based on the anisotropic mechanical model and mechanical parameters, the FEM numerical simulation and experimental methods are applied to analyze the fracture mechanical properties along different directions.

  9. Ground motion input in seismic evaluation studies

    International Nuclear Information System (INIS)

    Sewell, R.T.; Wu, S.C.

    1996-07-01

    This report documents research pertaining to conservatism and variability in seismic risk estimates. Specifically, it examines whether or not artificial motions produce unrealistic evaluation demands, i.e., demands significantly inconsistent with those expected from real earthquake motions. To study these issues, two types of artificial motions are considered: (a) motions with smooth response spectra, and (b) motions with realistic variations in spectral amplitude across vibration frequency. For both types of artificial motion, time histories are generated to match target spectral shapes. For comparison, empirical motions representative of those that might result from strong earthquakes in the Eastern U.S. are also considered. The study findings suggest that artificial motions resulting from typical simulation approaches (aimed at matching a given target spectrum) are generally adequate and appropriate in representing the peak-response demands that may be induced in linear structures and equipment responding to real earthquake motions. Also, given similar input Fourier energies at high-frequencies, levels of input Fourier energy at low frequencies observed for artificial motions are substantially similar to those levels noted in real earthquake motions. In addition, the study reveals specific problems resulting from the application of Western U.S. type motions for seismic evaluation of Eastern U.S. nuclear power plants

  10. Expermental Studies of quantitative evaluation using HPLC

    Directory of Open Access Journals (Sweden)

    Ki Rok Kwon

    2005-06-01

    Full Text Available Methods : This study was conducted to carry out quantitative evaluation using HPLC Content analysis was done using HPLC Results : According to HPLC analysis, each BVA-1 contained approximately 0.36㎍ melittin, and BVA-2 contained approximately 0.54㎍ melittin. But the volume of coating was so minute, slight difference exists between each needle. Conclusion : Above results indicate that the bee venom acupuncture can complement shortcomings of syringe usage as a part of Oriental medicine treatment, but extensive researches should be done for further verification.

  11. The use of fracture mechanics methodologies for NDT results evaluation and comparison

    International Nuclear Information System (INIS)

    Reale, S.

    1995-01-01

    In the general frame of analysing the interactions amongst the information from non destructive evaluation (NDE) and the methodologies to assess the integrity of a defective structure (such as fracture mechanics), the aim of the paper is to analyse and compare, in terms of indices related to safety margins, NDE results from round robin testing trials to acheive assessments of capabilities and limitations.A structural integrity/fracture mechanics approach for evaluating and comparing results from non destructive techniques is presented. Safety factors can be associated to flaws detected and characterized by inspections (estimated flaws) and to flaws actually present (reference flaws). The mismatch between safety factors associated to estimated flaws and safety factors associated to reference flaws can be used to assess capabilities and limitations of procedures and techniques in use for inspections.As an example, to show how the above procedure is applied and its potential as a method of data evaluation and comparison, the NDE results produced by the PISC (project for the inspection of steel components) activity have been considered. (orig.)

  12. Study of the Mechanical Behavior of a Hyperelastic Membrane

    Directory of Open Access Journals (Sweden)

    Bourbaba Houaria

    2014-04-01

    Full Text Available The benefits in emloying plastics material in microfluidic devices manufactures are extremely attractive that include reduced cost and simplified manufacturing procedures, particularly when compared to silicon. An additional benefit is the wide range of available plastic materials which allow the manufacturer to choose materials' properties suitable for their specific application. The Polydimethylsiloxane is commonly used in a wide range of microfluidic applications due to its flexibility and low cost. In addition the properties of the Polymethyl methacrylate such as the low cost, high transparency, and good chemical properties are needed in microfluidics applications. In this paper, we have used Finit Elements method to simulate the mechanical behavior of Polydimethylsiloxane and Polymethylmethacrylate using hyper elastic and linear elastic model. Sevral parameters have been studied; such as, thickness and number of mesh in order to optimize the dimension of the membrane. Also, we have studied the impact of the mesh form on the membrane’s displacement.

  13. The Importance of Specifying and Studying Causal Mechanisms in School-Based Randomised Controlled Trials: Lessons from Two Studies of Cross-Age Peer Tutoring

    Science.gov (United States)

    Morris, Stephen P.; Edovald, Triin; Lloyd, Cheryl; Kiss, Zsolt

    2016-01-01

    Based on the experience of evaluating 2 cross-age peer-tutoring interventions, we argue that researchers need to pay greater attention to causal mechanisms within the context of school-based randomised controlled trials. Without studying mechanisms, researchers are less able to explain the underlying causal processes that give rise to results from…

  14. Mechanical and morphological evaluation of age-related changes in the Beagle spine

    International Nuclear Information System (INIS)

    Gillett, N.A.; Gerlach, R.; Cassidy, J.; Brown, S.

    1986-01-01

    Age-related changes were evaluated in the spines of Beagle dogs by biomechanical testing, radiology and pathology. Thirty age-matched healthy Beagle dogs were divided into five groups having mean ages of 2, 5, 8, 11, and 14 years. Spinal radiographs of anesthetized dogs were taken prior to euthanasia and on defleshed pines following necropsy. Cervical, thoracic, and lumbar segments were tested in compression to calculate peak stress, peak strain, and elastic modulus. Adjacent spinal segments were examined histologically. Histological evidence of the disc degeneration and changes in the mechanical properties of the intervertebral disc joint preceded radiographical evidence of spondylosis. Changes in the mechanical properties of the disc space were probably a result of the disc degeneration rather than the spondylytic lesions. 3 references, 4 figures

  15. Development of centrifuge modeling for evaluating the mechanisms of collapse above underground openings

    International Nuclear Information System (INIS)

    Davis, B.C.; Kutter, B.L.; Chang, J.D.L.

    1988-01-01

    Improved prediction of surface collapse above an underground cavity is important in many LLNL programs, including Nuclear Test. To improve the predictive capability, LLNL must better understand the mechanisms involved in the process of collapse. The research aims to develop the centrifuge technique for modeling mechanisms of underground collapse in soil. The authors will also evaluate the adequacy of existing constitutive or flow models of soils for modeling underground collapse. During FY 86, using the centrifuge at University of California, Davis, the authors developed the basic centrifugal modeling technique, conducted experiments, and modeled the process on a computer. In FY 87, they continued to develop the experimental method and analyze results. Results to date have shown that the model dimensions are not necessarily the critical dimensions (i.e., those determining the adequacy of the model). Rather, the critical dimension is the diameter of the chimney above the opening that develops during collapse

  16. Evaluation of the mechanical properties of carbon fiber after electron beam irradiation

    International Nuclear Information System (INIS)

    Giovedi, Claudia; Diva Brocardo Machado, Luci; Augusto, Marcos; Segura Pino, Eddy; Radino, Patricia

    2005-01-01

    Carbon fibers are used as reinforcement material in epoxy matrix in advanced composites. An important aspect of the mechanical properties of composites is associated to the adhesion between the surface of the carbon fiber and the epoxy matrix. This paper aimed to the evaluation of the effects of EB irradiation on the tensile properties of two different carbon fibers prepared as resin-impregnated specimens. The fibers were EB irradiated before the preparation of the resin-impregnated specimens for mechanical tests. Observations of the specimens after breakage have shown that EB irradiation promoted significant changes in the failure mode. Furthermore, the tensile strength data obtained for resin-impregnated specimens prepared with carbons fibers previously irradiated presented a slight tendency to be higher than those obtained from non-irradiated carbon fibers

  17. Evaluating morphology and mechanical properties of glass-reinforced natural hydroxyapatite composites.

    Science.gov (United States)

    Yazdanpanah, Z; Bahrololoom, M E; Hashemi, B

    2015-01-01

    Hydroxyapatite has been used in a wide variety of biomedical applications and it can be produced from natural resources such as bovine bone. This material does not have acceptable mechanical properties by itself. In the present work, hydroxyapatite composites with different weight percentages of sodalime glass were made and sintered at different temperatures (800-1200°C). Eventually the properties such as density, micro hardness, compressive strength and wear of specimens were evaluated. Specific percentages of glass additive increased the density and hardness of specimens due to increasing the sintering temperature. The hardness and density of specimens were decreased with higher percentage of glass additive. Moreover, the results of compressive test showed that increasing the glass addition increases the compressive performance. Furthermore, the SEM micrographs on worn specimens showed that the mechanism of wear was abrasive. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Tractive performance evaluation of seafloor tracked trencher based on laboratory mechanical measurements

    Directory of Open Access Journals (Sweden)

    Meng Wang

    2016-03-01

    Full Text Available To evaluate the tractive performance of tracked trencher on seafloor surface, a new shear stress-displacement empirical model was proposed for saturated soft-plastic soil (SSP model. To validate the SSP model, a test platform, where track segment shear test can be performed in seafloor soil simulacrum (bentonite water mixture, was built. Series shear tests were carried out. Test results indicate that the SSP model can describe the mechanical behavior of track segment with good approximation in seafloor soil simulacrum. Through analyzing the main external forces applied to seafloor tracked trencher during the uniform linear trenching process, a drawbar pull prediction model was deduced with the SSP model. A tracked walking mechanism of the seafloor tracked trencher prototype was built, and verification tests were carried out. Test results indicate that this prediction model was feasible and effective; moreover, from another side, this conclusion also proved that the SSP model was effective.

  19. Evaluation of ethanol aged PVDF: diffusion, crystallinity and dynamic mechanical thermal properties

    International Nuclear Information System (INIS)

    Silva, Agmar J.J.; Costa, Marysilvia F.

    2015-01-01

    This work discuss firstly the effect of the ethanol fuel absorption by PVDF at 60°C through mass variation tests. A Fickian character was observed for the ethanol absorption kinetics of the aged PVDF at 60°C. In the second step, the dynamic mechanical thermal properties (E’, E’, E” and tan δ) of the PVDF were evaluated through dynamic mechanical thermal analysis (DMTA). The chemical structure of the materials was analyzed by X-ray diffraction analysis (XRD), and significant changes in the degree of crystallinity were verified after the aging. However, DMTA results showed a reduction in the storage modulus (E') of the aged PVDF, which was associated to diffusion of ethanol and swelling of the PVDF, which generated a prevailing plasticizing effect and led to reduction of its structural stiffness. (author)

  20. Mechanical Properties of Boehmite Evaluated by Atomic Force Microscopy Experiments and Molecular Dynamic Finite Element Simulations

    International Nuclear Information System (INIS)

    Fankhanel, J.; Daum, B.; Kempe, A.; Rolfes, R.; Silbernagl, D.; Khorasani, M.Gh.Z.; Sturm, H.; Sturm, H.

    2016-01-01

    Boehmite nanoparticles show great potential in improving mechanical properties of fiber reinforced polymers. In order to predict the properties of nanocomposites, knowledge about the material parameters of the constituent phases, including the boehmite particles, is crucial. In this study, the mechanical behavior of boehmite is investigated using Atomic Force Microscopy (AFM) experiments and Molecular Dynamic Finite Element Method (MDFEM) simulations. Young’s modulus of the perfect crystalline boehmite nanoparticles is derived from numerical AFM simulations. Results of AFM experiments on boehmite nanoparticles deviate significantly. Possible causes are identified by experiments on complementary types of boehmite, that is, geological and hydrothermally synthesized samples, and further simulations of imperfect crystals and combined boehmite/epoxy models. Under certain circumstances, the mechanical behavior of boehmite was found to be dominated by inelastic effects that are discussed in detail in the present work. The studies are substantiated with accompanying X-ray diffraction and Raman experiments.

  1. Study of growth mechanism of conducting polymers by pulse radiolysis

    International Nuclear Information System (INIS)

    Coletta, Cecilia

    2016-01-01

    Today conductive polymers have many applications in several devices. For these reasons they have received much attention in recent years. Despite intensive research, the mechanism of conducting polymers growth is still poorly understood and the methods of polymerization are limited to two principal ways: chemical and electrochemical synthesis. On the other hand, the complex properties of polymers can be controlled only if a good knowledge of polymerization process is acquired. In this case, it is possible to control the process during the synthesis (functionalization, hydrophilicity, chain length, doping level), and consequently to improve the conductive properties of the synthesized polymers. Water radiolysis represents an easy and efficient method of synthesis comparing to chemical and electrochemical polymerization routes. It enables the polymerization under soft conditions: ambient temperature and pressure, without any external dopant. Among all conductive polymers, poly(3, 4-ethylenedioxy-thiophene) (PEDOT, a derivative of poly-thiophene) and poly-Pyrrole (PPy) have gained some large scale applications for their chemical and physical proprieties. The aim of the present work was the synthesis of PEDOT and PPy in aqueous solution and the study of their growth mechanism by pulsed radiolysis. Thanks to the electron accelerator ELYSE, the use of pulsed radiolysis coupled with time-resolved absorption spectroscopy allowed to study the kinetics of polymerization. The first transient species involved in the mechanism were identified by time resolved spectroscopy and the rate constants were determined. First, the reaction of hydroxyl radicals onto EDOT and Py monomers was studied, as well as the corresponding radiation induced polymerization. Then, the study was transposed to others oxidizing radicals such as CO3 .- , N 3 . and SO 4 .- at different pHs. This approach allowed to check and to highlight the influence of oxidizing species onto the first transient species

  2. Methodic of practical study teaching on subject 'Characteristic mechanical oscillations'

    International Nuclear Information System (INIS)

    Tenchurina, A.R.

    2006-01-01

    In this article the methodic of the undertaking the practical lesson for subject 'the own mechanical vibrations' is considered and offered the algorithm of the problem decision the finding of the vibration period for the different mechanical systems. (author)

  3. Contribution to diffusion mechanism study in amorphous metallic alloys

    International Nuclear Information System (INIS)

    Delaye, Jean-Marc

    1993-01-01

    This work is dedicated to the study of the vacancy diffusion mechanism in mono-elementary and binary amorphous Lennard-Jones systems, by a molecular dynamics method. The first chapter is a review of the preceding works performed before the beginning of this thesis, the method of simulation is described in the second chapter. We showed in the following chapters that the vacancies, introduced by the removal of one atom, remain stable on a large percentage of sites, especially in the binary system. By calculating some thermodynamical values, formation and migration enthalpies and entropies, we showed that the vacancy mechanism is magnified in a disordered system, as compared to a crystal of the same composition, and therefore can explain the magnitudes of the experimental diffusion coefficients. In parallel, to measure diffusion coefficients, we have settled an experimental method based on the evolution of the resistivity of a multilayer sample during interdiffusion, a gold-silver multilayer in our case (chapter six). By measurements under pressure, the activation volume is determined and our results agree well with the preceding ones. (author) [fr

  4. Mechanism of nitrogen removal in wastewater lagoon: a case study.

    Science.gov (United States)

    Vendramelli, Richard A; Vijay, Saloni; Yuan, Qiuyan

    2017-06-01

    Ammonia being a nutrient facilitates the growth of algae in wastewater and causes eutrophication. Nitrate poses health risk if it is present in drinking water. Hence, nitrogen removal from wastewater is required. Lagoon wastewater treatment systems have become common in Canada these days. The study was conducted to understand the nitrogen removal mechanisms from the existing wastewater treatment lagoon system in the town of Lorette, Manitoba. The lagoon system consists of two primary aerated cells and two secondary unaerated cells. Surface samples were collected periodically from lagoon cells and analysed from 5 May 2015 to 9 November 2015. The windward and leeward sides of the ponds were sampled and the results were averaged. It was found that the free ammonia volatilization to the atmosphere is responsible for most of the ammonia removal. Ammonia and nitrate assimilation into biomass and biological growth in the cells appears to be the other mechanisms of nitrogen removal over the monitoring period. Factors affecting the nitrogen removal efficiency were found to be pH, temperature and hydraulic residence time. Also, the ammonia concentration in the effluent from the wastewater treatment lagoon was compared with the regulatory standard.

  5. Integrity evaluation of power plant components by fracture mechanics and related techniques

    International Nuclear Information System (INIS)

    Mukherjee, B.; Vanderglas, M.L.; Davies, P.H.

    1982-01-01

    Power plant components can be subject to unexpected failures with serious consequences, unless careful attention is paid to minute crack defects and their possible growth. The Linear Elastic Fracture Mechanics approach to structural integrity evaluation, as it appears in the ASME Code, is discussed. Projects related to material data generation and the development of structural analysis methods to make the above method usable are described. Several integrity-related questions outside the scope of the Code guidelines are documented, concluding with comments on possible future developments

  6. Evaluation of quantum mechanics path integrals by the approximations exact on a class of polynomial functionals

    International Nuclear Information System (INIS)

    Lobanov, Yu.Yu.; Shidkov, E.P.

    1987-01-01

    The method for numerical evaluation of path integrals in Eucledean quantum mechanics without lattice discretization is elaborated. The method is based on the representation of these integrals in the form of functional integrals with respect to the conditional Wiener measure and on the use of the derived approximate exact on a class of polynomial functionals of a given degree. By the computations of non-perturbative characteristics, concerned the topological structure of vacuum, the advantages of this method versus lattice Monte-Carlo calculations are demonstrated

  7. Radiation damage studies on the optical and mechanical properties of plastic scintillators

    International Nuclear Information System (INIS)

    Mizue Hamada, Margarida; Roberto Rela, Paulo; Eduardo da Costa, Fabio; Henrique de Mesquita, Carlos

    1999-01-01

    This paper describes the radiation damage studies on a large volume plastic scintillator based in polystyrene doped with PPO and POPOP. The consequences on their mechanical and scintillation properties were evaluated before and after irradiation with different dose rates of 60 Co gamma radiation, in several doses. The optical results show a significant difference in the radiation susceptibility, when the plastic scintillator is irradiated at low rate (0.1 kGy/h) with that irradiated at high dose rate (85 kGy/h). The losses in the optical and mechanical properties increase as the irradiation dose is increased. The damage evaluated by the transmittance, emission intensity, pulse height and tensile strength was normalized as a damage fraction and fitted by a bi-exponential function. It was observed that the damage for irradiation is not permanent and it obeys a bi-exponential function

  8. Evaluation of Detrimental Effects on Mechanical Properties of Zry-4 Due to Hydrogen Absorption by means of Scanning Electron Microscopy (SEM) In-Situ Observation of Crack Propagation

    International Nuclear Information System (INIS)

    Fernandez, L; Fernandez, G.E; Bertolino, G; Meyer, G

    2001-01-01

    The study of mechanical properties degradation of zirconium alloys due to hydrides assumes fundamental importance in the nuclear industry.During normal nuclear reactors operation, structural parts absorbed hydrogen generated from radiolysis of water, causing detrimental effects on mechanical properties.As a consequence, these materials are easily cracked in the presence of mechanical solicitation due to loss of ductility of the hydride-phase.The presence of cracks indicates fracture mechanic as the most suitable methodology in the study of mechanical properties degradation.In this work we used the crack tip opening displacement (CTOD) criteria to evaluate the detrimental effects on mechanical properties with the observation in SEM of crack propagation.The samples used were SEN (B) of Zry-4 and cathodic homogenous charged with hydrogen concentrations lower than 400 ppm

  9. Mechanical strength evaluation of the glass base material in the JRR-3 neutron guide tube

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Tetsuya [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-02-01

    The lifetime of the thermal neutron guide tube installed JRR-3 was investigated after 6 years from their first installation. And it was confirmed that a crack had been piercing into the glass base material of the side plate of the neutron guide tube. The cause of the crack was estimated as a static fatigue of the guide tube where an inside of the tube had been evacuated and stressed as well as an embrittlement of the glass base material by gamma ray irradiation. In this report, we evaluate the mechanical strength of the glass base material and estimate the time when the base material gets fatigue fracture. Furthermore, we evaluate a lifetime of the neutron guide tube and confirm the validity of update timing in 2000 and 2001 when the thermal neutron guide tubes T1 and T2 were exchanged into those using the super mirror. (author)

  10. Fracture mechanics evaluation of cast duplex stainless steel after thermal aging

    International Nuclear Information System (INIS)

    Tujikura, Y.; Urata, S.

    1999-01-01

    For the primary coolant piping of PWRs in Japan, cast duplex stainless steel, which is excellent in terms of strength, corrosion resistance and weldability, has conventionally been used. Cast duplex stainless steel contains the ferrite phase in the austenite matrix, and thermal aging after long-term service is known to decrease fracture toughness. Therefore, we evaluated the integrity of the primary coolant piping for an initial PWR plant in Japan by means of elastic plastic fracture mechanics. The evaluation results show that the crack will not grow into an unstable fracture and the integrity of the piping will be secure, even when such through-wall crack length is assumed to be as large as the fatigue crack length grown for a service period of up to 60 years. (orig.)

  11. Fracture mechanics evaluation of cast duplex stainless steel after thermal aging

    Energy Technology Data Exchange (ETDEWEB)

    Tujikura, Y.; Urata, S. [Kansai Electr. Power Co., Inc., Osaka (Japan). General Office of Nucl. and Fossil Power Production

    1999-07-01

    For the primary coolant piping of PWRs in Japan, cast duplex stainless steel, which is excellent in terms of strength, corrosion resistance and weldability, has conventionally been used. Cast duplex stainless steel contains the ferrite phase in the austenite matrix, and thermal aging after long-term service is known to decrease fracture toughness. Therefore, we evaluated the integrity of the primary coolant piping for an initial PWR plant in Japan by means of elastic plastic fracture mechanics. The evaluation results show that the crack will not grow into an unstable fracture and the integrity of the piping will be secure, even when such through-wall crack length is assumed to be as large as the fatigue crack length grown for a service period of up to 60 years. (orig.)

  12. The upgrade of integrity analysis module and the mechanical behavior evaluation for the assembly duct

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Byoung Oon; Lee, Dong Uk; Kim, Young Il [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2002-05-01

    The high neutron fluxes and operating temperatures associated with KALIMER are inducing the important radiation damage phenomena, which can cause significant dimensional changes in the core components of the reactor.The thermo-mechanical analysis of the assembly ducts for KALIMER are mainly performed to evaluate the following items.1) change of reactivity. 2) force at pads on core assemblies. 3) withdrawal force at refueling. 4) loading and refueling deviation of assembly ducts. 5) bowing modes for control assembly. In this report, the model for the evaluation of reactivity change as well as the refueling model and the withdrawl force model are upgraded. And the reactivity change is considered as the most important parameter among the above items. Therefore, the sensitivity analyses mainly associated with reactivity change are carried out. As the results, the pad gap between the assembly ducts preliminary driven for keeping the (-) reactivity change. 9 refs., 24 figs., 2 tabs. (Author)

  13. Montmorillonite clay/polypropylene (HMSPP) nanocomposites: evaluation of thermal and mechanical properties

    International Nuclear Information System (INIS)

    Komatsu, L.G.H.; Oliani, W.L.; Lugao, A.B.; Parra, D.F.

    2014-01-01

    The evaluation of HMSPP (high melt strength polypropylene) properties in nanocomposites was done in composites of 0.1; 1; 3; 5; 10 wt% of Cloisite 20A clay. The PP-g-MA (polypropylene graft maleic anhydride) was the compatibilizer agent in the process of extrusion in twin-screw. Mechanical tests performed in the nanocomposites with higher clay content showed higher values of rupture in 5 and 10 wt% of Cloisite. The thermal properties were evaluate utilizing Calorimetry Differential Exploratory (DSC) and in the sample of 10 wt% of Cloisite were observed increase of the melting temperature and increase of crystallinity. The morphology was investigated by the Scanning Electron Microscopy (SEM) and Fourier Transformed Infrared (FTIR), in which the sample with lower clay amount, 1 wt% of Cloisite showed better dispersion of the clay. X-Ray Diffraction reported the clay intercalation in the sample with 5 wt% of clay. (author)

  14. Evaluation of environmental impacts during chemical mechanical polishing (CMP) for sustainable manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun Seop; Park, Sun Joon; Jeong, Hae Do [Pusan National University, Busan (Korea, Republic of)

    2013-02-15

    Reducing energy consumption has become a critical issue in manufacturing. The semiconductor industry in particular is confronted with environmental regulations on pollution associated with electric energy, chemical, and ultrapure water (UPW) consumptions. This paper presents the results of an evaluation of the environmental impacts during chemical mechanical polishing (CMP), a key process for planarization of dielectrics and metal films in ultra-large-scale integrated circuits. The steps in the CMP process are idling, conditioning, wetting, wafer loading/unloading, head dropping, polishing, and rinsing. The electric energy, CMP slurry, and UPW consumptions associated with the process and their impacts on global warming are evaluated from an environmental standpoint. The estimates of electric energy, slurry, and UPW consumptions as well as the associated greenhouse gas emissions presented in this paper will provide a technical aid for reducing the environmental burden associated with electricity consumption during the CMP process.

  15. Theoretical evaluation of a mechanism of precipitate-enhanced cavity swelling during irradiation

    International Nuclear Information System (INIS)

    Mansur, L.K.

    1981-03-01

    It is often observed experimentally in complex alloys such as the austenitic stainless steels that the largest cavities produced during irradiation are attached to second phase precipitate particles. One hypothesis that such observations suggest is that the precipitate-matrix interface may assist in the collection of irradiation-produced point defects which are channelled to the attached cavities. A theoretical analysis is developed to evaluate this mechanism. It is found that the growth of cavities attached to precipitates is increased compared to the growth of cavities in the matrix. The relative growth rates of the two types of cavities are also affected by differences in bias and differences in sink strength. The relationships required to evaluate these effects are developed and the consequences of enhanced point defect collection are explored in some detail

  16. Evaluation of fuel release rate and mechanism tests under RBCB conditions

    International Nuclear Information System (INIS)

    Adamson, M.G.

    1981-09-01

    This task includes theoretical evaluation of fuel/fission product release behavior from failed LMFBR fuel elements as well as an on-going experimental investigation of the mechanism of oxide fuel dispersal into flowing liquid sodium. The primary objectives of this work are to develop a fuel source term that can be used in predictive models for primary heat transfer system contamination and to understand the separate influences of important system variables (such as flow rate, oxygen impurity level) on this source term. The present report is written in two parts: the first, in condensed form, is an updated evaluation of fuel (U,Pu) and fission product release data, and the second describes the current status of supporting experimental work at General Electric's Vallecitos Laboratory

  17. Evaluation of antibacterial and antibiofilm mechanisms by usnic acid against methicillin-resistant Staphylococcus aureus.

    Science.gov (United States)

    Pompilio, Arianna; Riviello, Antonella; Crocetta, Valentina; Di Giuseppe, Fabrizio; Pomponio, Stefano; Sulpizio, Marilisa; Di Ilio, Carmine; Angelucci, Stefania; Barone, Luana; Di Giulio, Andrea; Di Bonaventura, Giovanni

    2016-10-01

    To evaluate the antibacterial and antibiofilm mechanisms of usnic acid (USN) against methicillin-resistant Staphylococcus aureus from cystic fibrosis patients. The effects exerted by USN at subinhibitory concentrations on S. aureus Sa3 strain was evaluated by proteomic, real-time PCR and electron microscopy analyses. Proteomic analysis showed that USN caused damage in peptidoglycan synthesis, as confirmed by microscopy. Real-time PCR analysis showed that antibiofilm activity of USN is mainly due to impaired adhesion to the host matrix binding proteins, and decreasing lipase and thermonuclease expression. Our data show that USN exerts anti-staphylococcal effects through multitarget inhibitory effects, thus confirming the rationale for considering it 'lead compound' for the treatment of cystic fibrosis infections.

  18. Radionuclide arthrogram with SPECT/CT for the evaluation of mechanical loosening of hip and knee prostheses

    International Nuclear Information System (INIS)

    Chew, C.G.; Lewis, P.; Middleton, F.; Wijngaard, R. van den; Deshaies, A.

    2010-01-01

    The Objective of this study was to evaluate the value of single photon emission computed tomography (SPECT)/CT in radionuclide arthrogram (RNA) for the assessment of mechanical loosening of hip and knee prostheses. A retrospective audit of 117 RNA SPECT/CTs evaluated by a single reader- 40 hips, (1 hemiarthroplasty) and 77 knees (12 unicompartmental). The detection of any radiotracer within the bone/prosthetic interface was deemed positive for loosening. The operative assessment of 29 hip and 44 knee prosthetic joints was known and used as the gold standard. A subsequent blinded reassessment of the planar images was performed and compared with the SPECT/CT results for 26 of the 29 hip and 42 of the 44 knee prostheses. The respective SPECT/CT versus planar results were as follows: hips- acetabular cup: sensitivity: 73 versus 0%; specificity: 71 versus 100%; positive predictive value: 62% versus indeterminate; negative predictive value: 80% versus 72% (p=0.0044). Hips- femoral component: sensitivity: 78 versus 63%; specificity: 90 versus 94%; positive predictive value: 78 versus 83%; negative predictive value: 90 versus 85% (p=0.2482). Knees- femoral component: sensitivity: 75 versus 17%; specificity 63 versus 97%; positive predictive value: 43 versus 67%; negative predictive value: 87 versus 74% (p=0.0001). Knees- tibial component: sensitivity: 86 versus 63%; specificity: 86 versus 76%; positive predictive value: 55 versus 38%; negative predictive value: 97 versus 90% (p=0.6831). For evaluation of mechanical loosening of the hip prosthesis SPECT/CT was significantly better than planar scanning for the acetabular cup, but not for the femoral stem. For evaluation of the knee prosthesis, a significant improvement was noted using SPECT/CT for the femoral component, and although superior results were also noted for the tibial component, statistical significance was not reached. Taking into account the limitations of this retrospective audit, the value of using RNA SPECT

  19. Mechanisms of change in psychotherapy for depression: An empirical update and evaluation of research aimed at identifying psychological mediators.

    Science.gov (United States)

    Lemmens, Lotte H J M; Müller, Viola N L S; Arntz, Arnoud; Huibers, Marcus J H

    2016-12-01

    We present a systematic empirical update and critical evaluation of the current status of research aimed at identifying a variety of psychological mediators in various forms of psychotherapy for depression. We summarize study characteristics and results of 35 relevant studies, and discuss the extent to which these studies meet several important requirements for mechanism research. Our review indicates that in spite of increased attention for the topic, advances in theoretical consensus about necessities for mechanism research, and sophistication of study designs, research in this field is still heterogeneous and unsatisfactory in methodological respect. Probably the biggest challenge in the field is demonstrating the causal relation between change in the mediator and change in depressive symptoms. The field would benefit from a further refinement of research methods to identify processes of therapeutic change. Recommendations for future research are discussed. However, even in the most optimal research designs, explaining psychotherapeutic change remains a challenge. Psychotherapy is a multi-dimensional phenomenon that might work through interplay of multiple mechanisms at several levels. As a result, it might be too complex to be explained in relatively simple causal models of psychological change. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Mechanical property test of natural rubber bearing for the evaluation of uncertainty value of seismic isolation devices

    International Nuclear Information System (INIS)

    Kim, Min Kyu; Kim, Jung Han; Choi, In Kil

    2012-01-01

    Seismic safety of NPP is one of the most important issues in a nuclear field after great east Japan earthquake in 2011. For the improvement of seismic safety of nuclear power plant, seismic isolation is the easiest solution for increasing the seismic safety. Otherwise, the application of seismic isolation devices for nuclear power plants doesn't make the seismic risk of NPP increases always. The rubber bearing have many uncertainties of material properties and large displacement should absorb according to the application of isolation devices. In this study, for the evaluation of uncertainty of the material properties of rubber bearing, material tests for rubber and mechanical properties test for natural rubber bearing were performed. For the evaluation of effect of hardness of rubber, 4 kinds of rubber hardness for material property tests and 2 kinds of rubber hardness for mechanical property test were considered. As a result, the variation of material properties is higher than that of mechanical properties of natural rubber bearings

  1. Evaluation of mechanical and thermal properties of insulation materials for HTS power devices at liquid nitrogen temperature

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Hyung Seop; Diaz, Mark Angelo [Dept. of Mechanical Design Engineering, Andong National University, Andong (Korea, Republic of)

    2017-06-15

    In superconducting power devices including power cables in which high temperature superconducting (HTS) tapes are utilized, a reliable electrical insulation should be achieved for its maximum performance. For an efficient design of HTS superconducting devices, a comparative evaluation of the mechanical and thermal propperties for various insulation materials at cryogenic temperatures is required. Especially, in the process of the property evaluation of the sheet-shaped insulation materials, anisotropy according to the machining direction should be considered because the mechanical and thermal properties are significantly influenced by the sample orientation. In this study, the cryogenic thermal and mechanical properties of various insulation material sheets such as PPLP, Cryoflex, Teflon, and Kapton were determined considering sample orientation. All samples tested at cryogenic temperature showed significantly higher tensile strength as compared with that of room temperature. The ultimate tensile strength at both temperature conditions significantly depended upon the sample orientation. The thermal properties of the insulation materials exhibited a slight difference among samples depending on the orientation: for the PPLP and Cryoflex, the CD orientation showed larger thermal contraction up to 77 K as compared to the MD one. MD samples in PPLP and Cryoflex showed a lower CTE and thermal contraction which made it more promising as an insulation material due to its comparable CTE with HTS CC tapes.

  2. Insights into the Reaction Mechanism of Aromatic Ring Cleavage by Homogentisate Dioxygenase: A Quantum Mechanical/Molecular Mechanical Study.

    Science.gov (United States)

    Qi, Yue; Lu, Jiarui; Lai, Wenzhen

    2016-05-26

    To elucidate the reaction mechanism of the ring cleavage of homogentisate by homogentisate dioxygenase, quantum mechanical/molecular mechanical (QM/MM) calculations were carried out by using two systems in different protonation states of the substrate C2 hydroxyl group. When the substrate C2 hydroxyl group is ionized (the ionized pathway), the superoxo attack on the substrate is the rate-limiting step in the catalytic cycle, with a barrier of 15.9 kcal/mol. Glu396 was found to play an important role in stabilizing the bridge species and its O-O cleavage product by donating a proton via a hydrogen-bonded water molecule. When the substrate C2 hydroxyl group is not ionized (the nonionized pathway), the O-O bond cleavage of the bridge species is the rate-limiting step, with a barrier of 15.3 kcal/mol. The QM/MM-optimized geometries for the dioxygen and alkylperoxo complexes using the nonionized model (for the C2 hydroxyl group) are in agreement with the experimental crystal structures, suggesting that the C2 hydroxyl group is more likely to be nonionized.

  3. Fracture Toughness Evaluation of a Ni2MnGa Alloy Through Micro Indentation Under Magneto-Mechanical Loading

    Science.gov (United States)

    Goanţă, Viorel; Ciocanel, Constantin

    2017-12-01

    Ni2MnGa is a ferromagnetic alloy that exhibits the shape memory effect either induced by an externally applied magnetic field or mechanical stress. Due to the former, the alloy is commonly called magnetic shape memory alloy or MSMA. The microstructure of the MSMA consists of tetragonal martensite variants (three in the most general case) that are characterized by a magnetization vector which is aligned with the short side of the tetragonal unit cell. Exposing the MSMA to a magnetic field causes the magnetization vector to rotate and align with the external field, eventually leading to variant reorientation. The variant reorientation is observed macroscopically in the form of recoverable strain of up to 6% [1, 2]. As the magnetic field induced reorientation happens instantaneously [1, 3], MSMAs are suitable for fast actuation, sensing, or power harvesting applications. However, actuation applications are limited by the maximum actuation stress of the material that is about 3.5MPa at approximately 2 to 3% reorientation strain. During MSMA fatigue magneto-mechanical characterization studies [4, 5] it was observed that cracks nucleate and grow on the surface of material samples, after a relatively small number of cycles, leading to loss in material performance. This triggered the need for understanding the mechanisms that govern crack nucleation and growth in MSMAs, as well as the nature of the material, i.e. ductile or brittle. The experimental study reported in this paper was carried out to determine material's fracture toughness, the predominant crack growth directions, and the orientation of the cracks relative to the mechanical loading direction and to the material's microstructure. A fixture has been developed to allow Vickers micro indentation of 3mm by 3mm by 20mm Ni2MnGa samples exposed to different levels of magnetic field and/or mechanical stress. Using the measured characteristics of the impression generated during micro indentation, the lengths of

  4. Cellular studies and interaction mechanisms of extremely low frequency fields

    Science.gov (United States)

    Liburdy, Robert P.

    1995-01-01

    Worldwide interest in the biological effects of ELF (extremely low frequency, level is to identify cellular responses to ELF fields, to develop a dose threshold for such interactions, and with such information to formulate and test appropriate interaction mechanisms. This review is selective and will discuss the most recent cellular studies directed at these goals which relate to power line, sinusoidal ELF fields. In these studies an interaction site at the cell membrane is by consensus a likely candidate, since changes in ion transport, ligand-receptor events such as antibody binding, and G protein activation have been reported. These changes strongly indicate that signal transduction (ST) can be influenced. Also, ELF fields are reported to influence enzyme activation, gene expression, protein synthesis, and cell proliferation, which are triggered by earlier ST events at the cell membrane. The concept of ELF fields altering early cell membrane events and thereby influencing intracellular cell function via the ST cascade is perhaps the most plausible biological framework currently being investigated for understanding ELF effects on cells. For example, the consequence of an increase due to ELF fields in mitogenesis, the final endpoint of the ST cascade, is an overall increase in the probability of mutagenesis and consequently cancer, according to the Ames epigenetic model of carcinogenesis. Consistent with this epigenetic mechanism and the ST pathway to carcinogenesis is recent evidence that ELF fields can alter breast cancer cell proliferation and can act as a copromoter in vitro. The most important dosimetric question being addressed currently is whether the electric (E) or the magnetic (B) field, or if combinations of static B and time-varying B fields represent an exposure metric for the cell. This question relates directly to understanding fundamental interaction mechanisms and to the development of a rationale for ELF dose threshold guidelines. The weight of

  5. Manual versus mechanical cardiopulmonary resuscitation. An experimental study in pigs

    Directory of Open Access Journals (Sweden)

    Wohlfart Björn

    2010-10-01

    Full Text Available Abstract Background Optimal manual closed chest compressions are difficult to give. A mechanical compression/decompression device, named LUCAS, is programmed to give compression according to the latest international guidelines (2005 for cardiopulmonary resuscitation (CPR. The aim of the present study was to compare manual CPR with LUCAS-CPR. Methods 30 kg pigs were anesthetized and intubated. After a base-line period and five minutes of ventricular fibrillation, manual CPR (n = 8 or LUCAS-CPR (n = 8 was started and run for 20 minutes. Professional paramedics gave manual chest compression's alternating in 2-minute periods. Ventilation, one breath for each 10 compressions, was given to all animals. Defibrillation and, if needed, adrenaline were given to obtain a return of spontaneous circulation (ROSC. Results The mean coronary perfusion pressure was significantly (p Conclusions LUCAS-CPR gave significantly higher coronary perfusion pressure and significantly fewer rib fractures than manual CPR in this porcine model.

  6. Comparative Study on New AQM Mechanisms for Congestion Control

    Directory of Open Access Journals (Sweden)

    Ramakrishna B B

    2013-09-01

    Full Text Available As usage of network goes increasing day by day, managing network traffic becomes a very difficult task. It is important to avoid high packet loss rates in the Internet. Congestion is the one of the major issue in the present networks. Congestion Control is one of the solutions adopted to solve the congestion issue and to control it. Numbers of queue management algorithms are proposed for congestion control and to reduce high packet loss rates. Active Queue Management (AQM is one such mechanism which provides better control over congestion. In this paper a study is made on recent load based AQM techniques that are proposed and its merits and shortfall is presented.

  7. A study on fixing force generation mechanism of ER gel

    International Nuclear Information System (INIS)

    Tanaka, H; Kakinuma, Y; Aoyama, T; Anzai, H

    2009-01-01

    Electro-rheological Gel (ERG) is a new functional elastomer which changes its surface frictional and adhesive property according to the intensity of applied electrical field. This unique property is called ERG effect. The upper sliding electrode placed on the surface of ERG is fixed by the adhesive effect of ERG under electrical field. Variable fixing forces due to adhesion are generated by this effect. However, relationship between physical factors and generated fixing force has not yet been clarified. In this study, physical mechanism of fixing phenomenon is elucidated experimentally from the view point of frictional force and adhesive force. From the results, empirical equation of generated fixing force is originally derived to establish the theory of ERG effect.

  8. A study on fixing force generation mechanism of ER gel

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, H; Kakinuma, Y; Aoyama, T [School of Integrated Design Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); Anzai, H [Fujikura kasei Co., Ltd., 2-6-15 Shibakouen, Minato-ku, Tokyo (Japan)], E-mail: h-tanaka@ina.sd.keio.ac.jp

    2009-02-01

    Electro-rheological Gel (ERG) is a new functional elastomer which changes its surface frictional and adhesive property according to the intensity of applied electrical field. This unique property is called ERG effect. The upper sliding electrode placed on the surface of ERG is fixed by the adhesive effect of ERG under electrical field. Variable fixing forces due to adhesion are generated by this effect. However, relationship between physical factors and generated fixing force has not yet been clarified. In this study, physical mechanism of fixing phenomenon is elucidated experimentally from the view point of frictional force and adhesive force. From the results, empirical equation of generated fixing force is originally derived to establish the theory of ERG effect.

  9. Molecular spectroscopic study for suggested mechanism of chrome tanned leather

    Science.gov (United States)

    Nashy, Elshahat H. A.; Osman, Osama; Mahmoud, Abdel Aziz; Ibrahim, Medhat

    2012-03-01

    Collagen represents the structural protein of the extracellular matrix, which gives strength of hides and/or skin under tanning process. Chrome tan is the most important tanning agent all over the world. The methods for production of leather evolved over several centuries as art and engineering with little understanding of the underlying science. The present work is devoted to suggest the most probable mechanistic action of chrome tan on hide proteins. First the affect of Cr upon hide protein is indicated by the studied mechanical properties. Then the spectroscopic characterization of the hide protein as well as chrome tanned leather was carried out with Horizontal Attenuated Total Reflection (HATR) FT-IR. The obtained results indicate how the chromium can attached with the active sites of collagen. Molecular modeling confirms that chromium can react with amino as well as carboxylate groups. Four schemes were obtained to describe the possible interactions of chrome tan with hide proteins.

  10. Evaluation of elevated temperature influence on mechanical properties of a commercial unrefined bagasse fiber-polypropylene composite

    Directory of Open Access Journals (Sweden)

    Foroogh Dastoorian

    2014-11-01

    Full Text Available An experimental investigation was conducted to evaluate the effect of elevated temperatures, ranging from room temperature to 80oC, on mechanical characteristics of a commercial bagasse fiber/polypropylene composite. The test results were used to determine the temperature dependencies of the mechanical properties of the studied composite material at temperatures up to 80°C in order to develop temperature adjustment factors for the use in structural applications. The results have shown that as temperature increases, the material become more ductile due to increased plastic deformation gets lower stiffness and fails at higher strains. The resulted adjustment factors were different for each loading mode and the results also have indicated that the influence of elevated temperatures on values of modulus was higher than that on strengths.

  11. Studies of photodynamic therapy: Investigation of physiological mechanisms and dosimetry

    Science.gov (United States)

    Woodhams, Josephine Helen

    Photodynamic therapy (PDT) is a treatment for a range of malignant and benign lesions using light activated photosensitising drugs in the presence of molecular oxygen. PDT causes tissue damage by a combination of processes involving the production of reactive oxygen species (in particular singlet oxygen). Since the PDT cytotoxic effect depends on oxygen, monitoring of tissue oxygenation during PDT is important for understanding the basic physiological mechanisms and dosimetry of PDT. This thesis describes the use of non-invasive, optical techniques based on visible light reflectance spectroscopy for the measurement of oxy- to deoxyhaemoglobin ratio or haemoglobin oxygen saturation (HbSat). HbSat was monitored at tissue sites receiving different light dose during aluminium disulphonated phthalocyanine (AIS2PC) PDT. Results are presented on real time PDT-induced changes in HbSat in normal tissue (rat liver) and experimental tumours, and its correlation with the final biological effect under different light regimes, including fractionated light delivery. It was found to some extent that changes in HbSat could indicate whether the tissue would be necrotic after PDT and it was concluded that online physiological dosimetry is feasible for PDT. The evaluation of a new photosensitiser for PDT called palladium-bacteriopheophorbide (WST09) has been carried out in normal and tumour tissue in vivo. WST09 was found to exert a strong PDT effect but was active only shortly after administration. WST09 produced substantial necrosis in colonic tumours whilst only causing a small amount of damage to the normal colon under certain conditions indicating a degree of selectivity. Combination therapy with PDT for enhancing the extent of PDT-induced damage has been investigated in vivo by using the photochemical internalisation (PCI) technique and Type 1 mechanism enhanced phototoxicity with indole acetic acid (IAA). PCI of gelonin using AIS2PC PDT in vivo after systemic administration of

  12. Some studies on arithmetical chaos in classical and quantum mechanics

    International Nuclear Information System (INIS)

    Bolte, J.

    1993-04-01

    Several aspects of classical and quantum mechanics applied to a class of strongly chaotic systems are studied. The latter consists of single particles moving without external forces on surfaces of constant negative Gaussian curvature whose corresponding fundamental groups are supplied with an arithmetic structure. It is shown that the arithmetical features of the considered systems lead to exceptional properties of the corresponding spectra of lengths of closed geodesics (periodic orbits). The most significant one is an exponential growth of degeneracies in these geodesic length spectra. Furthermore, the arithmetical systems are distinguished by a structure that appears as a generalization of geometric symmetries. These pseudosymmetries occur in the quantization of the classical arithmetic systems as Hecke operators, which form an infinite algebra of self-adjoint operators commuting with the Hamiltonian. The statistical properties of quantum energies in the arithmetical systems have previously been identified as exceptional. They do not fit into the general scheme of random matrix theory. It is shown with the help of a simplified model for the spectral form factor how the spectral statistics in arithmetical quantum chaos can be understood by the properties of the corresponding classical geodesic length spectra. A decisive role is played by the exponentially increasing multiplicities of lengths. The model developed for the level spacings distribution and for the number variance is compared to the corresponding quantities obtained from quantum energies for a specific arithmetical system. Finally, the convergence properties of a representation for the Selberg zeta function as a Dirichlet series are studied. It turns out that the exceptional classical and quantum mechanical properties shared by the arithmetical systems prohibit a convergence of this important function in the physically interesting domain. (orig.)

  13. Evaluation of mechanical properties of aluminium alloy–alumina–boron carbide metal matrix composites

    International Nuclear Information System (INIS)

    Vijaya Ramnath, B.; Elanchezhian, C.; Jaivignesh, M.; Rajesh, S.; Parswajinan, C.; Siddique Ahmed Ghias, A.

    2014-01-01

    Highlights: • Fabrication of MMC with aluminium alloy–alumina–boron carbide is done. • Different proportions of reinforcements are added. • The effects of varying proportions are studied. • Investigation on mechanical properties above composites is performed. • Failure morphology analysis is done using SEM. - Abstract: This paper deals with the fabrication and mechanical investigation of aluminium alloy, alumina (Al 2 O 3 ) and boron carbide metal matrix composites. Aluminium is the matrix metal having properties like light weight, high strength and ease of machinability. Alumina which has better wear resistance, high strength, hardness and boron carbide which has excellent hardness and fracture toughness are added as reinforcements. Here, the fabrication is done by stir casting which involves mixing the required quantities of additives into stirred molten aluminium. After solidification, the samples are prepared and tested to find the various mechanical properties like tensile, flexural, impact and hardness. The internal structure of the composite is observed using Scanning Electron Microscope (SEM)

  14. Study on AE in Mechanical Seal Lift-off Recognition of Mechanical Main Shaft

    Directory of Open Access Journals (Sweden)

    Erqing Zhang

    2014-06-01

    Full Text Available For the problem of the determination of lift-off position and the measurement of end face thickness for mechanical seal more difficult, the method based on acoustic emission signal end face lift-off condition monitoring technology for mechanical seal was proposed. The electric eddy current sensor made direct measurement in the internal of mechanical seal device, and the acoustic emission sensor was fixed in the outside for indirect measurement. The acoustic emission signals were de-noised by wavelet threshold de-noising method. The representative energy features were selected by wavelet packet energy spectrum algorithm. It was established that the Radial Basis Function neural network model used for identification of the mechanical seal lift-off position, and the extracted wavelet energy features as its input. It was confirmed accurate and effective that the acoustic emission identification technology through comparing with the data detected by electric eddy current sensor. So using the acoustic emission technology realized the identification of the mechanical seal lift-off position of mechanical main shaft from inside to outside. It is convenient to be used and promotion in industrial field.

  15. Luminescent microporous metal–organic framework with functional Lewis basic sites on the pore surface: Quantifiable evaluation of luminescent sensing mechanisms towards Fe{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Jun-Cheng [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, Shaanxi Key Laboratory of Physico-Inorganic Chemistry, College of Chemistry & Materials Science, Northwest University, Xi' an 710069 (China); Technology Promotion Center of Nano Composite Material of Biomimetic Sensor and Detecting Technology, Preparation and Application, Anhui Provincial Laboratory West Anhui University, Anhui 237012 (China); Guo, Rui-Li; Zhang, Wen-Yan [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, Shaanxi Key Laboratory of Physico-Inorganic Chemistry, College of Chemistry & Materials Science, Northwest University, Xi' an 710069 (China); Jiang, Chen [Technology Promotion Center of Nano Composite Material of Biomimetic Sensor and Detecting Technology, Preparation and Application, Anhui Provincial Laboratory West Anhui University, Anhui 237012 (China); Wang, Yao-Yu, E-mail: wyaoyu@nwu.edu.cn [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, Shaanxi Key Laboratory of Physico-Inorganic Chemistry, College of Chemistry & Materials Science, Northwest University, Xi' an 710069 (China)

    2016-11-15

    A systematic study has been conducted on a novel luminescent metal-organic framework, ([Zn(bpyp)(L-OH)]·DMF·2H{sub 2}O){sub n} (1), to explore its sensing mechanisms to Fe{sup 3+}. Structure analyses show that compound 1 exist pyridine N atoms and -OH groups on the pore surface for specific sensing of metal ions via Lewis acid-base interactions. On this consideration, the quenching mechanisms are studied and the processes are controlled by multiple mechanisms in which dynamic and static mechanisms are calculated, achieving the quantification evaluation of the quenching process. This work not only achieves the quantitative evaluation of the luminescence quenching but also provides certain insights into the quenching process, and the possible mechanisms explored in this work may inspire future research and design of target luminescent metal-organic frameworks (LMOFs) with specific functions. - Graphical abstract: A systematic study has been conducted on a novel luminescent metal-organic framework to explore its sensing mechanisms to Fe{sup 3+}. The quenching mechanisms are studied and the processes are controlled by multiple mechanisms in which dynamic and static mechanisms are calculated, achieving the quantification evaluation of the quenching process. - Highlights: • A novel porous luminescent MOF containing uncoordinated groups in interlayer channels was successfully synthesized. • The compound 1 can exhibit significant luminescent sensitivity to Fe{sup 3+}, which make its good candidate as luminescent sensor. • The corresponding dynamic and static quenching constants are calculated, achieving the quantification evaluation of the quenching process.

  16. Toward a Trust Evaluation Mechanism in the Social Internet of Things.

    Science.gov (United States)

    Truong, Nguyen Binh; Lee, Hyunwoo; Askwith, Bob; Lee, Gyu Myoung

    2017-06-09

    In the blooming era of the Internet of Things (IoT), trust has been accepted as a vital factor for provisioning secure, reliable, seamless communications and services. However, a large number of challenges still remain unsolved due to the ambiguity of the concept of trust as well as the variety of divergent trust models in different contexts. In this research, we augment the trust concept, the trust definition and provide a general conceptual model in the context of the Social IoT (SIoT) environment by breaking down all attributes influencing trust. Then, we propose a trust evaluation model called REK, comprised of the triad of trust indicators (TIs) Reputation, Experience and Knowledge. The REK model covers multi-dimensional aspects of trust by incorporating heterogeneous information from direct observation (as Knowledge TI), personal experiences (as Experience TI) to global opinions (as Reputation TI). The associated evaluation models for the three TIs are also proposed and provisioned. We then come up with an aggregation mechanism for deriving trust values as the final outcome of the REK evaluation model. We believe this article offers better understandings on trust as well as provides several prospective approaches for the trust evaluation in the SIoT environment.

  17. Toward a Trust Evaluation Mechanism in the Social Internet of Things

    Directory of Open Access Journals (Sweden)

    Nguyen Binh Truong

    2017-06-01

    Full Text Available In the blooming era of the Internet of Things (IoT, trust has been accepted as a vital factor for provisioning secure, reliable, seamless communications and services. However, a large number of challenges still remain unsolved due to the ambiguity of the concept of trust as well as the variety of divergent trust models in different contexts. In this research, we augment the trust concept, the trust definition and provide a general conceptual model in the context of the Social IoT (SIoT environment by breaking down all attributes influencing trust. Then, we propose a trust evaluation model called REK, comprised of the triad of trust indicators (TIs Reputation, Experience and Knowledge. The REK model covers multi-dimensional aspects of trust by incorporating heterogeneous information from direct observation (as Knowledge TI, personal experiences (as Experience TI to global opinions (as Reputation TI. The associated evaluation models for the three TIs are also proposed and provisioned. We then come up with an aggregation mechanism for deriving trust values as the final outcome of the REK evaluation model. We believe this article offers better understandings on trust as well as provides several prospective approaches for the trust evaluation in the SIoT environment.

  18. Probabilistic fracture mechanics analysis for leak-before-break evaluation of light water reactor's piping

    International Nuclear Information System (INIS)

    Yoshimura, Shinobu; Yagawa, Genki; Akiba, Hiroshi; Fujioka, Terutaka.

    1997-01-01

    This paper describes Probabilistic Fracture Mechanics (PFM) analyses for quantitative evaluation of the likelihood of Leak-Before-Break (LBB) of Light Water Reactor's (LWR's) piping. The PFM analyses in general assume probabilistic distributions of initial crack size, applied stress cycles, crack growth laws, fracture criteria, leakage detection capability, defect inspection capability and so on. Referring to the deterministic procedure for LBB evaluation, most appropriate PFM models and data for LBB evaluation are discussed. Here the LBB index is newly proposed in order to quantitatively evaluate the likelihood of LBB. Through intensive sensitivity analyses, it is clarified that the LBB is more likely to occur for larger diameter pipe; the performance of leakage detection significantly affects the LBB likelihood; the LBB likelihood increases with plant's aging even conservatively assuming leak detection capability; the R6 method (Category 1, Option 1) for fracture criterion gives very conservative results; and In-Service Inspection (ISI) reduces the increase rate of failure probability than the failure probability itself. (author)

  19. Evaluation of Mechanical Properties and Marginal Fit of Crowns Fabricated Using Commercially Pure Titanium and FUS-Invest

    Directory of Open Access Journals (Sweden)

    Jinshuang Wu

    2017-01-01

    Full Text Available This study investigated the mechanical properties and single crown accuracy of the tailor-made Fourth University Stomatology investment (FUS-invest for casting titanium. Background. Current investment for casting titanium is not optimal for obtaining high-quality castings, and the commercially available titanium investment is costly. Methods. Titanium specimens were cast using the tailor-made FUS-invest. The mechanical properties were tested using a universal testing machine. Fractured castings were characterized by energy-dispersive spectroscopy. 19 titanium crowns were produced using FUS-invest and another 19 by Symbion. The accuracy of crowns was evaluated. Results. The mechanical properties of the titanium cast by FUS-invest were elastic modulus 125.6 ± 8.8 GPa, yield strength 567.5 ± 11.1 MPa, tensile strength 671.2 ± 15.6 MPa, and elongation 4.6 ± 0.2%. For marginal fit, no significant difference (P>0.05 was found at four marker points of each group. For internal fit, no significant difference (P>0.05 was found between two groups, whereas significant difference (P<0.01 was found at different mark point of each group. Conclusions. The mechanical properties of titanium casted using FUS-invest fulfilled the ISO 9693 criteria. The marginal and internal fit of the titanium crowns using either the FUS-invest or Symbion were similar.

  20. Use of Computational Modeling to Evaluate Hypotheses About the Molecular and Cellular Mechanisms of Bystander Effects

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yuchao; Conolly, Rory B; Andersen, Melvin E.

    2006-11-21

    This report describes the development of a computational systems biology approach to evaluate the hypotheses of molecular and cellular mechanisms of adaptive response to low dose ionizing radiation. Our concept is that computational models of signaling pathways can be developed and linked to biologically based dose response models to evaluate the underlying molecular mechanisms which lead to adaptive response. For development of quantitatively accurate, predictive models, it will be necessary to describe tissues consisting of multiple cell types where the different types each contribute in their own way to the overall function of the tissue. Such a model will probably need to incorporate not only cell type-specific data but also spatial information on the architecture of the tissue and on intercellular signaling. The scope of the current model was more limited. Data obtained in a number of different biological systems were synthesized to describe a chimeric, “average” population cell. Biochemical signaling pathways involved in sensing of DNA damage and in the activation of cell cycle checkpoint controls and the apoptotic path were also included. As with any computational modeling effort, it was necessary to develop these simplified initial descriptions (models) that can be iteratively refined. This preliminary model is a starting point which, with time, can evolve to a level of refinement where large amounts of detailed biological information are synthesized and a capability for robust predictions of dose- and time-response behaviors is obtained.

  1. Examination of cadmium safety rod thermal test specimens and failure mechanism evaluation

    International Nuclear Information System (INIS)

    Thomas, J.K.; Peacock, H.B.; Iyer, N.C.

    1992-01-01

    The reactor safety rods may be subjected to high temperatures due to gamma heating after the core coolant level has dropped during the ECS phase of a hypothetical LOCA event. Accordingly, an experimental cadmium safety rod testing subtask was established as part of a task to address the response of reactor core components to this accident. Companion reports describe the experiments and a structural evaluation (finite element analysis) of the safety rod. This report deals primarily with the examination of the test specimens, evaluation of possible failure mechanisms, and confirmatory separate effects experiments. It is concluded that the failures observed in the cadmium safety rod thermal tests which occurred at low temperature (T 800 degrees C) with fast thermal ramp rates are concluded to be mechanical in nature without significant environmental degradation. Based on these tests, tasks were initiated to design and manufacture B 4 C safety rods to replace the cadmium safety rods. The B 4 C safety rods have been manufactured at this time and it is currently planned to charge them to the reactor in the near future. 60 refs

  2. Evaluation of thermo-mechanical properties data of carbon-based plasma facing materials

    International Nuclear Information System (INIS)

    Ulrickson, M.; Barabash, V.R.; Matera, R.; Roedig, M.; Smith, J.J.; Janev, R.K.

    1991-03-01

    This Report contains the proceedings, results and conclusions of the work done and the analysis performed during the IAEA Consultants' Meeting on ''Evaluation of thermo-mechanical properties data of carbon-based plasma facing materials'', convened on December 17-21, 1990, at the IAEA Headquarters in Vienna. Although the prime objective of the meeting was to critically assess the available thermo-mechanical properties data for certain types of carbon-based fusion relevant materials, the work of the meeting went well beyond this task. The meeting participants discussed in depth the scope and structure of the IAEA material properties database, the format of data presentation, the most appropriate computerized system for data storage, retrieval, exchange and management. The existing IAEA ALADDIN system was adopted as a convenient tool for this purpose and specific ALADDIN labelling schemes and dictionaries were established for the material properties data. An ALADDIN formatted test-file for the thermo-physical and thermo-mechanical properties of pyrolytic graphite is appended to this Report for illustrative purposes. (author)

  3. Microcomputed tomography and microfinite element modeling for evaluating polymer scaffolds architecture and their mechanical properties.

    Science.gov (United States)

    Alberich-Bayarri, Angel; Moratal, David; Ivirico, Jorge L Escobar; Rodríguez Hernández, José C; Vallés-Lluch, Ana; Martí-Bonmatí, Luis; Estellés, Jorge Más; Mano, Joao F; Pradas, Manuel Monleón; Ribelles, José L Gómez; Salmerón-Sánchez, Manuel

    2009-10-01

    Detailed knowledge of the porous architecture of synthetic scaffolds for tissue engineering, their mechanical properties, and their interrelationship was obtained in a nondestructive manner. Image analysis of microcomputed tomography (microCT) sections of different scaffolds was done. The three-dimensional (3D) reconstruction of the scaffold allows one to quantify scaffold porosity, including pore size, pore distribution, and struts' thickness. The porous morphology and porosity as calculated from microCT by image analysis agrees with that obtained experimentally by scanning electron microscopy and physically measured porosity, respectively. Furthermore, the mechanical properties of the scaffold were evaluated by making use of finite element modeling (FEM) in which the compression stress-strain test is simulated on the 3D structure reconstructed from the microCT sections. Elastic modulus as calculated from FEM is in agreement with those obtained from the stress-strain experimental test. The method was applied on qualitatively different porous structures (interconnected channels and spheres) with different chemical compositions (that lead to different elastic modulus of the base material) suitable for tissue regeneration. The elastic properties of the constructs are explained on the basis of the FEM model that supports the main mechanical conclusion of the experimental results: the elastic modulus does not depend on the geometric characteristics of the pore (pore size, interconnection throat size) but only on the total porosity of the scaffold. (c) 2009 Wiley Periodicals, Inc.

  4. Evaluation of mechanical properties in metal wire mesh supported selective catalytic reduction (SCR) catalyst structures

    Science.gov (United States)

    Rajath, S.; Siddaraju, C.; Nandakishora, Y.; Roy, Sukumar

    2018-04-01

    The objective of this research is to evaluate certain specific mechanical properties of certain stainless steel wire mesh supported Selective catalytic reduction catalysts structures wherein the physical properties of the metal wire mesh and also its surface treatments played vital role thereby influencing the mechanical properties. As the adhesion between the stainless steel wire mesh and the catalyst material determines the bond strength and the erosion resistance of catalyst structures, surface modifications of the metal- wire mesh structure in order to facilitate the interface bonding is therefore very important to realize enhanced level of mechanical properties. One way to enhance such adhesion properties, the stainless steel wire mesh is treated with the various acids, i.e., chromic acid, phosphoric acid including certain mineral acids and combination of all those in various molar ratios that could generate surface active groups on metal surface that promotes good interface structure between the metal- wire mesh and metal oxide-based catalyst material and then the stainless steel wire mesh is dipped in the glass powder slurry containing some amount of organic binder. As a result of which the said catalyst material adheres to the metal-wire mesh surface more effectively that improves the erosion profile of supported catalysts structure including bond strength.

  5. Evaluation of mechanical properties of weldments for reduced activation ferritic/martensitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Nakata, T. [Muroran Institute of Technology, Dept. of Materials Science and Engineeering, Muroran, Hokkaido (Japan); Tanigawa, H.; Ando, M. [Japan Atomic Energy Agency, Naga-gun, Ibaraki-ken (Japan); Komazaki, S.; Kohno, Y. [Muroran Institute of Technology, Muroran (Japan)

    2007-07-01

    Full text of publication follows: Reduced activation ferritic/martensitic steels are the first candidate material for fusion reactor, and will be used as the structural materials of ITER test blanket modules (TBM). TBM will be assembled by welding various parts, it is important to be clearly mechanical properties of weldments to qualify TBM structure. In this paper, unirradiated mechanical properties of weldments, which is consisted of weld metal, heat affected zone (HAZ) and base metal region, obtained from TIG and EB welded F82H IEA-heat were evaluated by tensile, Charpy impact and creep test. Charpy impact test revealed that impact properties of weld metal does not deteriorate compared with that of base metal. The creep tests were carried out at temperatures of 773-873 K and at stress levels of 130-280 MPa, with the specimens which include weld metal and HAZ region in the gage section. In these conditions, rupture time of weldments yield to about 100-1000 hours. In the high-stress range, creep lives of welded joint decreased about 40% of base metal. However, in the low-stress range, creep lives of welded joint decrease about 60 to 70% of base metal. The failure at fine grain HAZ region (Type IV failure) does not occur in these conditions. The mechanism of these properties deterioration will be discussed based on the detailed analyses on microstructure changes. (authors)

  6. Preliminary study of sintering of metallic niobium processed for mechanical milling

    International Nuclear Information System (INIS)

    Tamura, H.M.; Vurobi Junior, S.; Cintho, O.M.; Sandim, H.R.Z.; Leite, G.S.

    2010-01-01

    In present study was preliminary study of mechanical milling influence on preparing of metallic niobium powder for sintering. Sample of metallic niobium in powder passing in sieve no. 635 mesh was processed by mechanical milling in SPEX mill for 8 hours using power grinding of 7:1 and a nitrogen atmosphere. The powder was annealed at different temperatures, 900 deg C, 1000 deg C, 1100 deg C and 1200 deg C for 1 hour in an atmosphere of hydrogen and argon to study their crystallization, which then were formed into blank for analysis of the curves compressibility. These samples were also subjected to x-ray diffraction in that their data were compared between the annealing temperatures. We also evaluate the compressibility curves of niobium samples with and without grinding these samples were subjected to x-ray diffraction and fluorescence. (author)

  7. Handling time in economic evaluation studies.

    Science.gov (United States)

    Permsuwan, Unchalee; Guntawongwan, Kansinee; Buddhawongsa, Piyaluk

    2014-05-01

    The discount rates and time horizons used in a health technology assessment (HTA) can have a significant impact on the results, and thus the prioritization of technologies. Therefore, it is important that clear guidance be provided on the appropriate discount rates for cost and health effect and appropriate time horizons. In this paper we conduct a review of relevant case studies and guidelines and provide guidance for all researchers conducting economic evaluations of health technologies in the Thai context. A uniform discount rate of 3% is recommended for both costs and health effects in base case analyses. A sensitivity analysis should also be conducted, with a discount range of 0-6%. For technologies where the effects are likely to sustain for at least 30y ears, a rate of 4% for costs and 2% for health effects is recommended. The time horizon should be long enough to capture the full costs and effects of the programs.

  8. Evaluation of Tissue Interactions with Mechanical Elements of a Transscleral Drug Delivery Device

    Directory of Open Access Journals (Sweden)

    Jeffrey T. Borenstein

    2012-03-01

    Full Text Available The goal of this work was to evaluate tissue-device interactions due to implantation of a mechanically operated drug delivery system onto the posterior sclera. Two test devices were designed and fabricated to model elements of the drug delivery device—one containing a free-spinning ball bearing and the other encasing two articulating gears. Openings in the base of test devices modeled ports for drug passage from device to sclera. Porous poly(tetrafluoroethylene (PTFE membranes were attached to half of the gear devices to minimize tissue ingrowth through these ports. Test devices were sutured onto rabbit eyes for 10 weeks. Tissue-device interactions were evaluated histologically and mechanically after removal to determine effects on device function and changes in surrounding tissue. Test devices were generally well-tolerated during residence in the animal. All devices encouraged fibrous tissue formation between the sclera and the device, fibrous tissue encapsulation and invasion around the device, and inflammation of the conjunctiva. Gear devices encouraged significantly greater inflammation in all cases and a larger rate of tissue ingrowth. PTFE membranes prevented tissue invasion through the covered drug ports, though tissue migrated in through other smaller openings. The torque required to turn the mechanical elements increased over 1000 times for gear devices, but only on the order of 100 times for membrane-covered gear devices and less than 100 times for ball bearing devices. Maintaining a lower device profile, minimizing microscale motion on the eye surface and covering drug ports with a porous membrane may minimize inflammation, decreasing the risk of damage to surrounding tissues and minimizing disruption of device operation.

  9. Evaluating transient performance of servo mechanisms by analysing stator current of PMSM

    Science.gov (United States)

    Zhang, Qing; Tan, Luyao; Xu, Guanghua

    2018-02-01

    Smooth running and rapid response are the desired performance goals for the transient motions of servo mechanisms. Because of the uncertain and unobservable transient behaviour of servo mechanisms, it is difficult to evaluate their transient performance. Under the effects of electromechanical coupling, the stator current signals of a permanent-magnet synchronous motor (PMSM) potentially contain the performance information regarding servo mechanisms in use. In this paper, a novel method based on analysing the stator current of the PMSM is proposed for quantifying the transient performance. First, a vector control model is constructed to simulate the stator current behaviour in the transient processes of consecutive speed changes, consecutive load changes, and intermittent start-stops. It is discovered that the amplitude and frequency of the stator current are modulated by the transient load torque and motor speed, respectively. The stator currents under different performance conditions are also simulated and compared. Then, the stator current is processed using a local means decomposition (LMD) algorithm to extract the instantaneous amplitude and instantaneous frequency. The sample entropy of the instantaneous amplitude, which reflects the complexity of the load torque variation, is calculated as a performance indicator of smooth running. The peak-to-peak value of the instantaneous frequency, which defines the range of the motor speed variation, is set as a performance indicator of rapid response. The proposed method is applied to both simulated data in an intermittent start-stops process and experimental data measured for a batch of servo turrets for turning lathes. The results show that the performance evaluations agree with the actual performance.

  10. Avisalmvac: evaluation studies of stability and toxicity

    Directory of Open Access Journals (Sweden)

    Daniela Botus,

    2008-12-01

    Full Text Available In Pasteur Institute laboratories there was developed AVISALMVAC, a vaccine against avian Salmonella, a biological product that contains S. enteritidis and S. typhimurium bacterin, with oil adjuvant. This paper presents the results of the studies regarding the stability and toxicity evaluation of this vaccine stored under conditions recommended by the manufacturer (2-80C at the end of the period of validity. The vaccine stability was assessed by serological and histopathological analysis of samples from SPF chickens vaccinated with the product at the end of the period of validity. The study of Avisalmvac toxicity was carried out by inoculation of the product or its components on Vero cell monolayer, and the effects were microscopically recorded or by MTT test, applied at 6 days post-inoculation. Antibody titers recorded at 2 and 3 weeks post vaccination demonstrated the vaccine ability (used after an year since manufacture to induce synthesis of specific antibodies and therefore, the product stability was proven. Histopathological examinations carried out on samples taken at 18 days post vaccinationfrom the vaccination site (skeletal muscle and skin and spleen, did not show any lesions associated to vaccination with Avisalmvac. The cytotoxicity analysis made by inoculating the vaccine or its components on Vero cell monolayer and the microscopic examination did not record visible cytopathic effects for any vaccine dilutions or vaccine components. The cell metabolism evaluation by MTT assay made at 6 days after vaccine/vaccine components inoculation on Vero monolayer, shown the ability of the vaccine and oil adjuvant to stimulate cell metabolism, and a certain degree of toxicity / inhibition of dehydrogenase metabolism associated to one of emulsifier but at dilutions higher than those used in the vaccine formula.

  11. An Empirical Study of the Transmission Power Setting for Bluetooth-Based Indoor Localization Mechanisms.

    Science.gov (United States)

    Castillo-Cara, Manuel; Lovón-Melgarejo, Jesús; Bravo-Rocca, Gusseppe; Orozco-Barbosa, Luis; García-Varea, Ismael

    2017-06-07

    Nowadays, there is a great interest in developing accurate wireless indoor localization mechanisms enabling the implementation of many consumer-oriented services. Among the many proposals, wireless indoor localization mechanisms based on the Received Signal Strength Indication (RSSI) are being widely explored. Most studies have focused on the evaluation of the capabilities of different mobile device brands and wireless network technologies. Furthermore, different parameters and algorithms have been proposed as a means of improving the accuracy of wireless-based localization mechanisms. In this paper, we focus on the tuning of the RSSI fingerprint to be used in the implementation of a Bluetooth Low Energy 4.0 (BLE4.0) Bluetooth localization mechanism. Following a holistic approach, we start by assessing the capabilities of two Bluetooth sensor/receiver devices. We then evaluate the relevance of the RSSI fingerprint reported by each BLE4.0 beacon operating at various transmission power levels using feature selection techniques. Based on our findings, we use two classification algorithms in order to improve the setting of the transmission power levels of each of the BLE4.0 beacons. Our main findings show that our proposal can greatly improve the localization accuracy by setting a custom transmission power level for each BLE4.0 beacon.

  12. An Empirical Study of the Transmission Power Setting for Bluetooth-Based Indoor Localization Mechanisms

    Directory of Open Access Journals (Sweden)

    Manuel Castillo-Cara

    2017-06-01

    Full Text Available Nowadays, there is a great interest in developing accurate wireless indoor localization mechanisms enabling the implementation of many consumer-oriented services. Among the many proposals, wireless indoor localization mechanisms based on the Received Signal Strength Indication (RSSI are being widely explored. Most studies have focused on the evaluation of the capabilities of different mobile device brands and wireless network technologies. Furthermore, different parameters and algorithms have been proposed as a means of improving the accuracy of wireless-based localization mechanisms. In this paper, we focus on the tuning of the RSSI fingerprint to be used in the implementation of a Bluetooth Low Energy 4.0 (BLE4.0 Bluetooth localization mechanism. Following a holistic approach, we start by assessing the capabilities of two Bluetooth sensor/receiver devices. We then evaluate the relevance of the RSSI fingerprint reported by each BLE4.0 beacon operating at various transmission power levels using feature selection techniques. Based on our findings, we use two classification algorithms in order to improve the setting of the transmission power levels of each of the BLE4.0 beacons. Our main findings show that our proposal can greatly improve the localization accuracy by setting a custom transmission power level for each BLE4.0 beacon.

  13. Mechanisms of masked evaluative priming: task sets modulate behavioral and electrophysiological priming for picture and words differentially.

    Science.gov (United States)

    Kiefer, Markus; Liegel, Nathalie; Zovko, Monika; Wentura, Dirk

    2017-04-01

    Research with the evaluative priming paradigm has shown that affective evaluation processes reliably influence cognition and behavior, even when triggered outside awareness. However, the precise mechanisms underlying such subliminal evaluative priming effects, response activation vs semantic processing, are matter of a debate. In this study, we determined the relative contribution of semantic processing and response activation to masked evaluative priming with pictures and words. To this end, we investigated the modulation of masked pictorial vs verbal priming by previously activated perceptual vs semantic task sets and assessed the electrophysiological correlates of priming using event-related potential (ERP) recordings. Behavioral and electrophysiological effects showed a differential modulation of pictorial and verbal subliminal priming by previously activated task sets: Pictorial priming was only observed during the perceptual but not during the semantic task set. Verbal priming, in contrast, was found when either task set was activated. Furthermore, only verbal priming was associated with a modulation of the N400 ERP component, an index of semantic processing, whereas a priming-related modulation of earlier ERPs, indexing visuo-motor S-R activation, was found for both picture and words. The results thus demonstrate that different neuro-cognitive processes contribute to unconscious evaluative priming depending on the stimulus format. © The Author (2016). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

  14. Evaluation of Mechanical Properties and Medical Applications of Polycaprolactone Small Diameter Artificial Blood Vessels

    Directory of Open Access Journals (Sweden)

    Mahnazsadat Mirbagheri

    2017-03-01

    Full Text Available Increasing the cardiovascular diseases and decreasing the possibility of autograft surgery are important factors that cause the choice of artificial vascular graft as an alternative treatment method. In this regard, producing artificial grafts similar to natural vessels is an important purpose that has long been followed as a gold standard by many researchers worldwide. In addition, mechanical properties including strength, long patency, bio-compatibility and hydrophobicity are necessary properties to achieve ideal vascular grafts. Hence there are various factors such as polymer type and preparation methods, which contribute to suitable mechanical properties. The electrospinning as an optimized method on one side and biocompatible, degradable and semicrystalline polycaprolactone (PCL on the other side are used for their acceptable mechanical properties to manufacture synthetic vessels. In this study, PCL vascular grafts have been reviewed and a wide range of parameters affecting the improvement of mechanical properties and their performance have been described along with clinical applications. Therefore, by investigating and comparing single and composite PCL vascular grafts, we achieved acceptable results in the field of cell growth and adhesion as well as implanting grafts in animals such as rat and rabbit. By reviewing other studies, it was revealed that synthetic composite vessels made of PCL and natural polymers such as collagen and chitosan and synthetic polymers such as polyurethane (PU for long patency and acceptable cell adhesion have shown good clinical results.

  15. Investigating Heuristic Evaluation: A Case Study.

    Science.gov (United States)

    Goldman, Kate Haley; Bendoly, Laura

    When museum professionals speak of evaluating a web site, they primarily mean formative evaluation, and by that they primarily mean testing the usability of the site. In the for-profit world, usability testing is a multi-million dollar industry, while non-profits often rely on far too few dollars to do too much. Hence, heuristic evaluation is one…

  16. Computational Bench Testing to Evaluate the Short-Term Mechanical Performance of a Polymeric Stent.

    Science.gov (United States)

    Bobel, A C; Petisco, S; Sarasua, J R; Wang, W; McHugh, P E

    2015-12-01

    Over the last decade, there has been a significant volume of research focussed on the utilization of biodegradable polymers such as poly-L-lactide-acid (PLLA) for applications associated with cardiovascular disease. More specifically, there has been an emphasis on upgrading current clinical shortfalls experienced with conventional bare metal stents and drug eluting stents. One such approach, the adaption of fully formed polymeric stents has led to a small number of products being commercialized. Unfortunately, these products are still in their market infancy, meaning there is a clear non-occurrence of long term data which can support their mechanical performance in vivo. Moreover, the load carry capacity and other mechanical properties essential to a fully optimized polymeric stent are difficult, timely and costly to establish. With the aim of compiling rapid and representative performance data for specific stent geometries, materials and designs, in addition to reducing experimental timeframes, Computational bench testing via finite element analysis (FEA) offers itself as a very powerful tool. On this basis, the research presented in this paper is concentrated on the finite element simulation of the mechanical performance of PLLA, which is a fully biodegradable polymer, in the stent application, using a non-linear viscous material model. Three physical stent geometries, typically used for fully polymeric stents, are selected, and a comparative study is performed in relation to their short-term mechanical performance, with the aid of experimental data. From the simulated output results, an informed understanding can be established in relation to radial strength, flexibility and longitudinal resistance, that can be compared with conventional permanent metal stent functionality, and the results show that it is indeed possible to generate a PLLA stent with comparable and sufficient mechanical performance. The paper also demonstrates the attractiveness of FEA as a tool

  17. [A cyberbullying study: Analysis of cyberbullying, comorbidities and coping mechanisms].

    Science.gov (United States)

    Rémond, J-J; Kern, L; Romo, L

    2015-09-01

    Cyberbullying is a relatively new form of bullying. This bullying is committed by means of an electronic act, the transmission of a communication by message, text, sound, or image by means of an electronic device, including but limited to, a computer phone, wireless telephone, or other wireless communication device, computer, games console or pager. Cyberbullying is characterized by deliberately threatening, harassing, intimidating, or ridiculing an individual or group of individuals; placing an individual in reasonable fear of harm; posting sensitive, private information about another person without his/her permission; breaking into another person's account and/or assuming another individual's identity in order to damage that person's reputation or friendships. A review of the literature shows that between 6 and 40% of all youths have experienced cyberbullying at least once in their lives. Several cyberbullying definitions have been offered in the literature, many of which are derived from definitions of traditional bullying. In our study we asked clear definition of cyberbullying. Few studies explicate the psychosocial determinants of cyberbullying, and coping mechanisms. The authors of the literature recommend developing resiliency, but without analyzing the resilience factor. The first aim of this study was to determine the prevalence of adolescents and adults engaged in cyberbullying. The second aim was to examine the coping mechanisms and comorbidity factors associated with the cyberbullied people. The sample was composed of 272 adolescents (from a high school) and adults (mean age=16.44 ± 1). The Olweus Bully/Victim Questionnaire was used to identify profiles of cyberbullying. Coping mechanisms were investigated using the Hurt Disposition Scale (HDS) and the Brief Resilience Scale (BRS). Comorbidities were assessed using the Hospital Anxiety and Depression Scale (HAD), Liebowitz's Social Anxiety Scale (LSAS), and the Bermond-Vorst Alexithymia Questionnaire

  18. Research on evaluation of coupled thermo-hydro-mechanical phenomena in the near-field

    International Nuclear Information System (INIS)

    Chijimatsu, Masakazu; Imai, Hisashi; Fukutome, Kazuhito; Kayukawa, Koji; Sasaki, Hajime; Moro, Yoshiji

    2004-02-01

    After emplacement of the engineered barrier system (EBS), it is expected that the near-field environment will be impacted by phenomena such as heat dissipation by conduction and other heat transfer mechanisms, infiltration of groundwater from the surrounding rock in the engineered barrier system, stress imposed by the overburden pressure and generation of swelling pressure in the buffer due to water infiltration. In order to recognize and evaluate these coupled thermo-hydro-mechanical (THM) phenomena, it is necessary to make a confidence of the mathematical models and computer codes. Evaluating these coupled THM phenomena is important in order to clarify the initial transient behavior of the EBS within the near field. DECOVALEX project is an international co-operative project for the DEvelopment of COupled models and their VALidation against EXperiments in nuclear waste isolation and it is significance to participate this project and to apply the code for the validation. Therefore, we tried to apply the developed numerical code against the subjects of DECOVALEX. We carried out the simulation against the Task 1 (simulation of FEBEX in-situ full-scale experiment), Task 3 BMT1 (Bench Mark Test against the near field coupling phenomena) and Task 3 BMT2 (Bench Mark Test against the up-scaling of fractured rock mass). This report shows the simulation results against these tasks. Furthermore, technical investigations about the in-situ full-scale experiment (called Prototype Repository Project) in Aespoe HRL facility by SKB of Sweden were performed. In order to evaluate the coupled phenomena in the engineered barrier, we use the new swelling model based on the theoretical approach. In this paper, we introduce the modeling approach and applicability about the new model. (author)

  19. Mechanical properties of irradiated nanowires – A molecular dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Figueroa, Emilio [Grupo de NanoMateriales, Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla, 653 Santiago (Chile); Departamento de Física, Facultad de Ciencias Naturales, Matemática y del Medio Ambiente, Universidad Tecnológica Metropolitana, Santiago 7800002 (Chile); Tramontina, Diego [Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, 5500 Mendoza (Argentina); Instituto de Bioingeniería, Universidad de Mendoza, 5500 Mendoza (Argentina); Gutiérrez, Gonzalo, E-mail: gonzalo@fisica.ciencias.uchile.cl [Grupo de NanoMateriales, Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla, 653 Santiago (Chile); Bringa, Eduardo [Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, 5500 Mendoza (Argentina)

    2015-12-15

    In this work we study, by means of molecular dynamics simulation, the change in the mechanical properties of a gold nanowire with pre-existing radiation damage. The gold nanowire is used as a simple model for a nanofoam, made of connected nanowires. Radiation damage by keV ions leads to the formation of a stacking fault tetrahedron (SFT), and this defect leads to a reduced plastic threshold, as expected, when the nanowire is subjected to tension. We quantify dislocation and twin density during the deformation, and find that the early activation of the SFT as a dislocation source leads to reduced dislocation densities compared to the case without radiation damage. In addition, we observed a total destruction of the SFT, as opposed to a recent simulation study where it was postulated that SFTs might act as self-generating dislocation sources. The flow stress at large deformation is also found to be slightly larger for the irradiated case, in agreement with recent experiments. - Highlights: • Stacking Fault Tetrahedra (SFT) formation proceeds by cascades, containing typically a vacancy cluster and interstitials. • Applied tension leads to the destruction of the SFT, in contrast to a recently reported case of a SFT which soften the NW. • After the initial dislocation activity, strength is controlled by a few surviving dislocations.

  20. Analysis of Jovian decametric data: study of radio emission mechanisms

    International Nuclear Information System (INIS)

    Staelin, D.H.

    1986-01-01

    Catalogues of approx. 200 decametric arcs and approx. 200 gaps between arcs were studied, in an effort to reconcile the data with predictions for the model wherein reflections of Io-induced currents each emit in a conical pattern and yield a distinct radio arc. The most recent interpretations of this data suggest that these Io-produced Alfven waves persist for at least one or two passages of Io, and that the emission cone half angles are approx. 40 to 90 deg., varying from arc to arc. Below 1.2 MHz it was discovered that Jupiter emits radiation strongly modulated in frequency with periods of approx. 200 kHz; this quasi-sinusoidal emission (MSA) can shift more than 180 deg. in phase over periods of 6 seconds, although these shifts are usually much smaller. MSA is not strongly correlated with the longitudes of Io or Jupiter, and typically occurs in patches covering approx. 500 kHz or more for periods of a few minutes. Furthermore, this modulation sometimes resembles a train of impulses in frequency with exponential decays toward high frequencies. Comparison of these results with the previous studies of V-shaped S-bursts is suggestive of an emission mechanism

  1. Neural mechanisms of mindfulness and meditation: Evidence from neuroimaging studies

    Institute of Scientific and Technical Information of China (English)

    William; R; Marchand

    2014-01-01

    Mindfulness is the dispassionate,moment-by-moment awareness of sensations,emotions and thoughts.Mindfulness-based interventions are being increasingly used for stress,psychological well being,coping with chronic illness as well as adjunctive treatments for psychiatric disorders.However,the neural mechanisms associated with mindfulness have not been well characterized.Recent functional and structural neuroimaging studies are beginning to provide insights into neural processes associated with the practice of mindfulness.A review of this literature revealed compelling evidence that mindfulness impacts the function of the medial cortex and associated default mode network as well as insula and amygdala.Additionally,mindfulness practice appears to effect lateral frontal regions and basal ganglia,at least in some cases.Structural imaging studies are consistent with these findings and also indicate changes in the hippocampus.While many questions remain unanswered,the current literature provides evidence of brain regions and networks relevant for understanding neural processes associated with mindfulness.

  2. Studying Suspended Sediment Mechanism with Two-Phase PIV

    Science.gov (United States)

    Matinpour, H.; Atkinson, J. F.; Bennett, S. J.; Guala, M.

    2017-12-01

    Suspended sediment transport affects soil erosion, agriculture and water resources quality. Turbulent diffusion is the most primary force to maintain sediments in suspension. Although extensive previous literature have been studying the interactions between turbulent motion and suspended sediment, mechanism of sediments in suspension is still poorly understood. In this study, we investigate suspension of sediments as two distinct phases: one phase of sediments and another phase of fluid with turbulent motions. We designed and deployed a state-of-the-art two-phase PIV measurement technique to discriminate these two phases and acquire velocities of each phase separately and simultaneously. The technique that we have developed is employing a computer-vision based method, which enables us to discriminate sediment particles from fluid tracer particles based on two thresholds, dissimilar particle sizes and different particle intensities. Results indicate that fluid turbulence decreases in the presence of suspended sediments. Obtaining only sediment phase consecutive images enable us to compute fluctuation sediment concentration. This result enlightens understanding of complex interaction between the fluctuation velocities and the fluctuation of associated mass and compares turbulent viscosity with turbulent eddy diffusivity experimentally.

  3. Investigation research on the evaluation of a coupled thermo-hydro-mechanical-chemical phenomena. Outline report

    International Nuclear Information System (INIS)

    Chijimatsu, Masakazu; Amemiya, Kiyoshi; Neyama, Atsushi; Iwata, Hiroshi; Nakagawa, Koichi; Ishihara, Yoshinao; Shiozaki, Isao; Sagawa, Hiroshi

    2002-02-01

    In order to realize a coupling analysis in the near field of the geological disposal system, this study has been studied on the addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES) and preliminary coupling analysis by using development environmental tool (Diffpack) for numerical analysis. (1) In order to prepare the strategy on the addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES), we have studied on the requirement of THAMES-Transport and methodology of coupling analysis. After that we set out modification plan by the Eulerian-Lagrangian (EL) method. (2) Based on the document of modification plan, we have done addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES) and carried out verification analysis in order to confirm on the accuracy of THAMES-Transport. (3) In order to understand on the behavior of NaCl in the porewater under the coupled thermo-hydro-mechanical phenomena in the HLW engineered barrier system, we have calculated coupling phenomenon by using THAMES-Transport. Transportation and concentration phenomena of NaCl are calculated but precipitation of NaCl is not occurred under the analysis conditions in this report. (4) In order to confirm about feasibility of coupling analysis under the development environmental tool (Diffpack) for numerical analysis, we have carried out on the design work and writing program of the preliminary coupling system. In this study, we have adopted existing transport model (HYDROGEOCHEM) and geochemical model (phreeqe60) for preliminary coupling system. (5) In order to confirm program correctness of preliminary coupling system, we have carried out benchmarking analysis by using existing reactive-transport analysis code (HYDROGEOCHEM). (6) We have been prepared short-range development plan based on through the modification study of THAMES and writing program of the preliminary coupling

  4. Investigation research on the evaluation of a coupled thermo-hydro-mechanical-chemical phenomena. Result report

    International Nuclear Information System (INIS)

    Chijimatsu, Masakazu; Amemiya, Kiyoshi; Shiozaki, Isao; Neyama, Atsushi; Iwata, Hiroshi; Nakagawa, Koichi; Ishihara, Yoshinao; Sagawa, Hiroshi

    2002-02-01

    In order to realize a coupling analysis in the near field of the geological disposal system, this study has been studied on the addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES) and preliminary coupling analysis by using development environmental tool (Diffpack) for numerical analysis. (1) In order to prepare the strategy on the addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES), we have studied on the requirement of THAMES-Transport and methodology of coupling analysis. After that we set out modification plan by the Eulerian-Lagrangian (EL) method. (2) Based on the document of modification plan, we have done addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES) and carried out verification analysis in order to confirm on the accuracy of THAMES-Transport. (3) In order to understand on the behavior of NaCl in the porewater under the coupled thermo-hydro-mechanical phenomena in the HLW engineered barrier system, we have calculated coupling phenomenon by using THAMES-Transport. Transportation and concentration phenomena of NaCl are calculated but precipitation of NaCl is not occurred under the analysis conditions in this report. (4) In order to confirm about feasibility of coupling analysis under the development environmental tool (Diffpack) for numerical analysis, we have carried out on the design work and writing program of the preliminary coupling system. In this study, we have adopted existing transport model (HYDROGEOCHEM) and geochemical model (phreeqe 60) for preliminary coupling system. (5) In order to confirm program correctness of preliminary coupling system, we have carried out benchmarking analysis by using existing reactive-transport analysis code (HYDROGEOCHEM). (6) We have been prepared short-range development plan based on through the modification study of THAMES and writing program of the preliminary coupling

  5. Evaluation of the mechanical properties and porcelain bond strength of cobalt-chromium dental alloy fabricated by selective laser melting.

    Science.gov (United States)

    Wu, Lin; Zhu, Haiting; Gai, Xiuying; Wang, Yanyan

    2014-01-01

    Limited information is available regarding the microstructure and mechanical properties of dental alloy fabricated by selective laser melting (SLM). The purpose of this study was to evaluate the mechanical properties of a cobalt-chromium (Co-Cr) dental alloy fabricated by SLM and to determine the correlation between its microstructure and mechanical properties and its porcelain bond strength. Five metal specimens and 10 metal ceramic specimens were fabricated to evaluate the mechanical properties of SLM Co-Cr dental alloy (SLM alloy) with a tensile test and its porcelain bond strength with a 3-point bending test. The relevant properties of the SLM alloy were compared with those of the currently used Co-Cr dental alloy fabricated with conventional cast technology (cast alloy). The Student t test was used to compare the results of the SLM alloy and the cast alloy (α=.05). The microstructure of the SLM alloy was analyzed with a metallographic microscope; the metal ceramic interface of the SLM porcelain bonded alloy was studied with scanning electron microscopy, energy dispersive x-ray spectroscopy, and an electron probe microanalyzer. Both the mean (standard deviation) yield strength (884.37 ± 8.96 MPa) and tensile strength (1307.50 ±10.65 MPa) of the SLM alloy were notably higher than yield strength (568.10 ± 30.94 MPa) and tensile strength (758.73 ± 25.85 MPa) of the currently used cast alloy, and the differences were significant (P.05). Microstructure analysis suggested that the SLM alloy had a dense and obviously orientated microstructure, which led to excellent mechanical properties. Analysis from scanning electron microscopy, energy dispersive x-ray spectroscopy, and the electron probe microanalyzer indicated that the SLM alloy had an intermediate layer with elemental interpenetration between the alloy and the porcelain, which resulted in an improved bonding interface. Compared with the currently used cast alloy, SLM alloy possessed improved mechanical

  6. Study on the mechanism of seepage flow in the grouting for multiple fractured model

    International Nuclear Information System (INIS)

    Nishigaki, Makoto; Mikake, Shin-ichiro

    2002-01-01

    The purpose of study is to improve the grouting method for fractured rock masses. In this paper, the results on the fundamental phenomenon for grasping the properties of grouting injection and seepage flow are discussed. The case of grouting stage is studied about the multiple hydraulic fractured apertures in the injected borehole. So the theory on the mechanism is constructed, and experiment is executed in order to verify the availability of the theory. From the results, it is shown that Bernoulli's law is able to prove the behavior of the grouting. And the theoretical evaluation is executed on the experiential procedure of the grouting. (author)

  7. Seismic fatigue life evaluation of mechanical structures using energy balance equation

    International Nuclear Information System (INIS)

    Minagawa, Keisuke; Fujita, Satoshi; Kitamura, Seiji; Okamura, Shigeki

    2009-01-01

    Evaluation of seismic resistant performance for severe earthquakes is required, because of occurrence of earthquakes which exceed the design criteria. Additionally, quantitative evaluation of cumulative damage by earthquake is also required. In this study, the energy balance equation is applied to the evaluation. The energy balance equation expresses integral information of response, so that the energy balance equation is adequate for the evaluation of the influence of cumulative load such as seismic response. At first, vibration experiment that leads experimental model to fatigue failure by continuous vibration disturbance is conducted. As a result of the experiment, relation between fatigue failure and energy balance equation is confirmed. Then the relation is proved from the viewpoint of hysteresis energy, and consistency between energy balance equation and hysteresis energy is confirmed. Finally, we adopted cumulative damage rule to energy balance equation in order to expect the fatigue life under random waves that have various input acceleration. (author)

  8. Evaluation of the Chemical and Mechanical Properties of Hardening High-Calcium Fly Ash Blended Concrete.

    Science.gov (United States)

    Fan, Wei-Jie; Wang, Xiao-Yong; Park, Ki-Bong

    2015-09-07

    High-calcium fly ash (FH) is the combustion residue from electric power plants burning lignite or sub-bituminous coal. As a mineral admixture, FH can be used to produce high-strength concrete and high-performance concrete. The development of chemical and mechanical properties is a crucial factor for appropriately using FH in the concrete industry. To achieve sustainable development in the concrete industry, this paper presents a theoretical model to systematically evaluate the property developments of FH blended concrete. The proposed model analyzes the cement hydration, the reaction of free CaO in FH, and the reaction of phases in FH other than free CaO. The mutual interactions among cement hydration, the reaction of free CaO in FH, and the reaction of other phases in FH are also considered through the calcium hydroxide contents and the capillary water contents. Using the hydration degree of cement, the reaction degree of free CaO in FH, and the reaction degree of other phases in FH, the proposed model evaluates the calcium hydroxide contents, the reaction degree of FH, chemically bound water, porosity, and the compressive strength of hardening concrete with different water to binder ratios and FH replacement ratios. The evaluated results are compared to experimental results, and good consistencies are found.

  9. Intraocular robotic interventional surgical system (IRISS): Mechanical design, evaluation, and master-slave manipulation.

    Science.gov (United States)

    Wilson, Jason T; Gerber, Matthew J; Prince, Stephen W; Chen, Cheng-Wei; Schwartz, Steven D; Hubschman, Jean-Pierre; Tsao, Tsu-Chin

    2018-02-01

    Since the advent of robotic-assisted surgery, the value of using robotic systems to assist in surgical procedures has been repeatedly demonstrated. However, existing technologies are unable to perform complete, multi-step procedures from start to finish. Many intraocular surgical steps continue to be manually performed. An intraocular robotic interventional surgical system (IRISS) capable of performing various intraocular surgical procedures was designed, fabricated, and evaluated. Methods were developed to evaluate the performance of the remote centers of motion (RCMs) using a stereo-camera setup and to assess the accuracy and precision of positioning the tool tip using an optical coherence tomography (OCT) system. The IRISS can simultaneously manipulate multiple surgical instruments, change between mounted tools using an onboard tool-change mechanism, and visualize the otherwise invisible RCMs to facilitate alignment of the RCM to the surgical incision. The accuracy of positioning the tool tip was measured to be 0.205±0.003 mm. The IRISS was evaluated by trained surgeons in a remote surgical theatre using post-mortem pig eyes and shown to be effective in completing many key steps in a variety of intraocular surgical procedures as well as being capable of performing an entire cataract extraction from start to finish. The IRISS represents a necessary step towards fully automated intraocular surgery and demonstrated accurate and precise master-slave manipulation for cataract removal and-through visual feedback-retinal vein cannulation. Copyright © 2017 John Wiley & Sons, Ltd.

  10. A Practical Quantum Mechanics Molecular Mechanics Method for the Dynamical Study of Reactions in Biomolecules.

    Science.gov (United States)

    Mendieta-Moreno, Jesús I; Marcos-Alcalde, Iñigo; Trabada, Daniel G; Gómez-Puertas, Paulino; Ortega, José; Mendieta, Jesús

    2015-01-01

    Quantum mechanics/molecular mechanics (QM/MM) methods are excellent tools for the modeling of biomolecular reactions. Recently, we have implemented a new QM/MM method (Fireball/Amber), which combines an efficient density functional theory method (Fireball) and a well-recognized molecular dynamics package (Amber), offering an excellent balance between accuracy and sampling capabilities. Here, we present a detailed explanation of the Fireball method and Fireball/Amber implementation. We also discuss how this tool can be used to analyze reactions in biomolecules using steered molecular dynamics simulations. The potential of this approach is shown by the analysis of a reaction catalyzed by the enzyme triose-phosphate isomerase (TIM). The conformational space and energetic landscape for this reaction are analyzed without a priori assumptions about the protonation states of the different residues during the reaction. The results offer a detailed description of the reaction and reveal some new features of the catalytic mechanism. In particular, we find a new reaction mechanism that is characterized by the intramolecular proton transfer from O1 to O2 and the simultaneous proton transfer from Glu 165 to C2. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Physical and mechanical properties evaluation of Acropora palmata coralline species for bone substitution applications.

    Science.gov (United States)

    Alvarez, K; Camero, S; Alarcón, M E; Rivas, A; González, G

    2002-05-01

    The search for ideal materials for bone substitution has been a challenge for many decades. Numerous natural and synthetic materials have been studied. For this application, exoskeletons of coral have been considered a good alternative given its tendency to resorption, biocompatibility and similarity to the mineral bone phase. Very few studies of these materials consider a detailed analysis of the structure-property relationship. The purpose of this work was to carry out the microstructural characterization of a coralline species named Acropora palmata and the determination of the mechanical and physico-chemical properties. Measurements of hardness, compressive strength, bulk density and apparent porosity were performed. From these results it was determined that this marine coral species could be an alternative xenograft due to its mechanical properties and osteoconductive nature.

  12. Study of the Mechanical Properties and Vibration Isolation Performance of a Molecular Spring Isolator

    Directory of Open Access Journals (Sweden)

    Muchun Yu

    2016-01-01

    Full Text Available Molecular Spring Isolator (MSI is a novel passive vibration isolation technique, providing High-Static-Low-Dynamic (HSLD stiffness based on the use of molecular spring material. The molecular spring material is a solid-liquid mixture consisting of water and hydrophobic nanoporous materials. Under a certain level of external pressure, water molecules can intrude into the hydrophobic pores of nanoporous materials, developing an additional solid-liquid interface. Such interfaces are able to store, release, and transform mechanical energy, providing properties like mechanical spring. Having been only recently developed, the basic mechanic properties of a MSI have not been studied in depth. This paper focuses on the stiffness influence factors, the dynamic frequency response, and the vibration isolation performance of a MSI; these properties help engineers to design MSIs for different engineering applications. First, the working mechanism of a MSI is introduced from a three-dimensional general view of the water infiltration massive hydrophobic nanoporous pores. Next, a wide range of influence factors on the stiffness properties of MSI are studied. In addition, the frequency response functions (FRFs of the MSI vibration isolation system are studied utilizing the matching method based on equivalent piecewise linear (EPL system. Finally, the vibration isolation properties of MSI are evaluated by force transmissibility.

  13. PRICING ELECTRIC POWER UNDER A HYBRID WHOLESALE MECHANISM: EVALUATING THE TURKISH ELECTRICITY MARKET

    Directory of Open Access Journals (Sweden)

    Hatice Karahan

    2013-01-01

    Full Text Available During the restructuring process, Turkish electricity sector has gone through significant changes both in wholesale and retail markets. In this framework, the Market Financial Settlement Mechanism established for handling market imbalances has become a spot market in time. So, it can be claimed that the wholesale electricity market in Turkey is a hybrid mechanism composed of bilateral contracts and the balancing market. On the other hand, the main target of liberalization program is providing consumers with affordable electric power. Hence, this study attempts to explore the link between retail tariffs for ineligible consumers and prices in the two wholesale mechanisms, in the period after the launch of the day-ahead market. Findings suggest that regulated wholesale prices are more effective in the determination of end-user prices, whereas unregulated ones might have a price reduction effect in case the free market dominates. However, the volatility in spot market prices implies that the sector would better continue with the hybrid mechanism for quite some time.

  14. Evaluation of mechanical properties of hybrid fiber (hemp, jute, kevlar) reinforced composites

    Science.gov (United States)

    Suresha, K. V.; Shivanand, H. K.; Amith, A.; Vidyasagar, H. N.

    2018-04-01

    In today's world composites play wide role in all the engineering fields. The reinforcement of composites decides the properties of the material. Natural fiber composites compared to synthetic fiber possesses poor mechanical properties. The solution for this problem is to use combination of natural fiber and synthetic fiber. Hybridization helps to improve the overall mechanical properties of the material. In this study, hybrid reinforced composites of Hemp fabric/Kevlar fabric/Epoxy and Jute fabric/ Kevlar fabric/Epoxy composites are fabricated using Simple hand layup technique followed by Vacuum bagging process. Appropriate test methods as per standards and guidelines are followed to analyze mechanical behavior of the composites. The mechanical characteristics like tensile, compression and flexural properties of the hybrid reinforced composites are tested as per the ASTM standards by series of tensile test; compression test and three point bending tests were conducted on the hybrid composites. A quantitative relationship between the Hemp fabric/Kevlar fabric/Epoxy and Jute/ Kevlar fabric/Epoxy has been established with constant thickness.

  15. Mechanical evaluation of a new sand control screen for SAGD applications

    Energy Technology Data Exchange (ETDEWEB)

    Woiceshyn, G. [Society of Petroleum Engineers, Canadian Section, Calgary, AB (Canada)]|[Absolute Completion Technologies, Calgary, AB (Canada); Toffanin, E. [Society of Petroleum Engineers, Canadian Section, Calgary, AB (Canada)]|[Schlumberger Canada Ltd., Calgary, AB (Canada); Xie, J.; Wagg, B. [Society of Petroleum Engineers, Canadian Section, Calgary, AB (Canada)]|[C-FER Technologies, Edmonton, AB (Canada); Fan, C. [C-FER Technologies, Edmonton, AB (Canada)

    2008-10-15

    Steam assisted gravity drainage (SAGD) wells normally require the deployment of an open hole completion combining sand control with adequate mechanical strength to withstand aggressive installation loads and serve operational loads. Slotted liners have traditionally been used in western Canada, mainly because of low cost relative to wire-wrapped screen or premium mesh screens. However, slotting base pipe can weaken the mechanical strength. The slot width can also change as the liner deforms under certain load conditions. Operators are therefore interested in alternative technologies to reduce incidents of mechanical failure and loss of sand control of slotted liners in SAGD wells. This paper presented the flush absolute cartridge system (FACS), a newly developed sand screen onto which a 25.4 diameter fusion bonded metal laminate cartridge is directly mounted and secured directly into the base pipe wall. The paper discussed a finite element analysis study that was conducted in order to independently quantify its mechanical strength and integrity for use in SAGD operations. The paper described the liner, as well as the disc geometry, construction and properties. The paper also listed the potential applications for FACS screens and provided a description of the finite element analysis. It was concluded that although FACS satisfies the basic operational criteria, it has very limited ability to absorb additional strain at the end of the thermal cycle. 10 refs., 4 tabs., 22 figs.

  16. On the Evaluation of the Mechanical Behaviour of Structural Glass Elements

    OpenAIRE

    Costa, S.; Miranda, M.; Varum, H.; Teixeira-Dias, F.

    2005-01-01

    Glass can be considered to be a high-technology engineering material with a multifunctional potential for structural applications. However, the conventional approach to the use of glass is often based only on its proper-ties of transparency and isolation. It is thus highly appropriate and necessary to study the mechanical behaviour of this material and to develop adequate methods and models leading to its characterisation. It is evident that the great potential of growth for structural glass ...

  17. Theoretical Study of Sodium-Water Surface Reaction Mechanism

    Science.gov (United States)

    Kikuchi, Shin; Kurihara, Akikazu; Ohshima, Hiroyuki; Hashimoto, Kenro

    Computational study of the sodium-water reaction at the gas (water) - liquid (sodium) interface has been carried out using the ab initio (first-principle) method. A possible reaction channel has been identified for the stepwise OH bond dissociations of a single water molecule. The energetics including the binding energy of a water molecule on the sodium surface, the activation energies of the bond cleavages, and the reaction energies, have been evaluated, and the rate constants of the first and second OH bond-breakings have been compared. It was found that the estimated rate constant of the former was much larger than the latter. The results are the basis for constructing the chemical reaction model used in a multi-dimensional sodium-water reaction code, SERAPHIM, being developed by Japan Atomic Energy Agency (JAEA) toward the safety assessment of the steam generator (SG) in a sodium-cooled fast reactor (SFR).

  18. Theoretical study of sodium-water surface reaction mechanism

    International Nuclear Information System (INIS)

    Kikuchi, Shin; Kurihara, Akikazu; Ohshima, Hiroyuki; Hashimoto, Kenro

    2012-01-01

    Computational study of the sodium-water reaction at the gas (water) - liquid (sodium) interface has been carried out using the ab initio (first-principle) method. A possible reaction channel has been identified for the stepwise OH bond dissociations of a single water molecule. The energetics including the binding energy of a water molecule on the sodium surface, the activation energies of the bond cleavages, and the reaction energies, have been evaluated, and the rate constants of the first and second OH bond-breakings have been compared. It was found that the estimated rate constant of the former was much larger than the latter. The results are the basis for constructing the chemical reaction model used in a multi-dimensional sodium-water reaction code, SERAPHIM, being developed by Japan Atomic Energy Agency (JAEA) toward the safety assessment of the steam generator (SG) in a sodium-cooled fast reactor (SFR). (author)

  19. Study of the mechanical properties of brown coal

    Energy Technology Data Exchange (ETDEWEB)

    Okruszek, Z

    1980-01-01

    The techniques and the results of studies of the mechanical properties of brown coal discovered in a zone adjacent to the location of the Rogowiec power plant (Poland) are described. The studies were conducted by the geotechnical laboratory of the Polytechnical Institute in the city of Lodz. Included in the program of studies were: tests of the brown coal (eight samples with a diameter to height ratio of d/h = 10.0/7.5; 11.1/7.8; 9.3/8.8; 8.1/6.8; 8.5/9.4; 8.0/8.8; 7.9/7.6 adn 8.8/8.6; dimensions in centimeters) for single axis compression (destroying stress was found to be 0.778; 0.660; 0.376; 0.804; 0.140; 0.472; 0.408 and 0.278 MPa); tests of samples (five units) for shear strength (the chip force is 0.36; 0.46; 0.39; 0.11 and 0.36 kilonewtons); tests of the samples (two samples, both with a diameter of 3.8 cm and a height of 7.6 cm) for stretching (the destructive force is 50.1 and 54.9 kilonewtons); odometric tests to determine the odometric modulus of compressibility of the brown coal (a total of four samples; three of which were loaded by a force in the range of 0.6-1.2 MPa and one in the range of 0-1.1 MPa; the odometric modulus of compressibility is in the range of 45.1 to 116.7 depending on the loading conditions) and tests for triple axial compression (two samples, both with a diameter of 3.8 cm and a height of 7.6 cm; the destroying pressure was found to be equal to 0.5 and 0.27 MPa).

  20. Study on the mechanical properties of a HMS-PP nanocomposite with a Brazilian bentonite

    International Nuclear Information System (INIS)

    Fermino, D.M.; Parra, D.F.; Lugao, A.B.; Oliani, W.L.; Valenzuela-Diaz, F.R.

    2010-01-01

    This work concerns to the study of the mechanical behavior of the nanocomposite HMSPP - Polypropylene High Melt Strength (obtained at a dose of 12.5 kGy) and a bentonite clay Brazilian Paraiba (PB), known as 'Chocolate' in concentrations of 5 and 10% by weight, comparison of to one American Clay, cloisite 20A nanocomposite was done. Agent compatibilizer polypropylene-graft, known as maleic anhydride (PP-g-AM) was addict 3% concentration thought technique melt intercalation using a twin-screw extruder and the specimens were prepared by injection process. The mechanical behavior was evaluated by strength, flexural strength and impact tests. The morphology of the nanocomposites was studied by the technique of Scanning Electron Microscopy (SEM), while the organophilic bentonite and nanocomposites were characterized by X-ray diffraction (XRD) and infrared (FTIR). (author)

  1. HRCT evaluation of microtia: A retrospective study

    Directory of Open Access Journals (Sweden)

    Aruna R Patil

    2012-01-01

    Full Text Available Purpose: To determine external, middle, and inner ear abnormalities on high-resolution computed tomography (HRCT of temporal bone in patients with microtia and to predict anatomic external and middle ear anomalies as well as the degree of functional hearing impairment based on clinical grades of microtia. Materials and Methods: It was a retrospective study conducted on Indian population. Fifty-two patients with microtia were evaluated for external, middle, and inner ear anomalies on HRCT of temporal bone. Clinical grading of microtia was done based on criteria proposed by Weerda et al. in 37 patients and degree of hearing loss was assessed using pure tone audiometry or brainstem-evoked response in 32 patients. Independent statistical correlations of clinical grades of micotia with both external and middle ear anomalies detected on HRCT and the degree of hearing loss were finally obtained. Results: The external, middle, and inner ear anomalies were present in 93.1%, 74.5%, and 2.7% patients, respectively. Combined cartilaginous and bony external auditory canal atresia (EAC was the most common anatomic abnormality in our group of microtia patients. Hypoplastic mesotympanum represented the commonest middle ear anomaly. The incidence of combined ossicular dysplasia and facial canal anomalies was lower as compared to other population groups; however, we recorded a greater incidence of cholesteatoma. Both these factors can have a substantial impact on outcome of patients planned for surgery. We found no significant association between grades of microtia and external or middle ear anomalies. Similarly, no significant association was found between lower grades of microtia (grade I and II and degree of hearing loss. However, association between grade III microtia and degree of hearing loss was significant. A significant association between congenital cholesteatoma and degree of pneumatization of atretic plate and mastoid process not previously studied

  2. HRCT evaluation of microtia: A retrospective study

    International Nuclear Information System (INIS)

    Patil, Aruna R; Bhalla, Ashu; Gupta, Pankaj; Goyal, Deepali; Vishnubhatla, Sreenivas; Ramavat, Anurag; Sharma, Suresh

    2012-01-01

    To determine external, middle, and inner ear abnormalities on high-resolution computed tomography (HRCT) of temporal bone in patients with microtia and to predict anatomic external and middle ear anomalies as well as the degree of functional hearing impairment based on clinical grades of microtia. It was a retrospective study conducted on Indian population. Fifty-two patients with microtia were evaluated for external, middle, and inner ear anomalies on HRCT of temporal bone. Clinical grading of microtia was done based on criteria proposed by Weerda et al. in 37 patients and degree of hearing loss was assessed using pure tone audiometry or brainstem-evoked response in 32 patients. Independent statistical correlations of clinical grades of micotia with both external and middle ear anomalies detected on HRCT and the degree of hearing loss were finally obtained. The external, middle, and inner ear anomalies were present in 93.1%, 74.5%, and 2.7% patients, respectively. Combined cartilaginous and bony external auditory canal atresia (EAC) was the most common anatomic abnormality in our group of microtia patients. Hypoplastic mesotympanum represented the commonest middle ear anomaly. The incidence of combined ossicular dysplasia and facial canal anomalies was lower as compared to other population groups; however, we recorded a greater incidence of cholesteatoma. Both these factors can have a substantial impact on outcome of patients planned for surgery. We found no significant association between grades of microtia and external or middle ear anomalies. Similarly, no significant association was found between lower grades of microtia (grade I and II) and degree of hearing loss. However, association between grade III microtia and degree of hearing loss was significant. A significant association between congenital cholesteatoma and degree of pneumatization of atretic plate and mastoid process not previously studied was also recorded in our study

  3. Evaluation of piping fracture analysis method by benchmark study, 1

    International Nuclear Information System (INIS)

    Takahashi, Yukio; Kashima, Koichi; Kuwabara, Kazuo

    1987-01-01

    Importance of strength evaluation methods for cracked piping is growing with the progress of the rationalization of the nuclear piping system based on the leak-before-break concept. As an analytical tool, finite element method is principally used. To obtain the reliable solutions by the finite element programs, it is important to grasp the influences of various factors on the solutions. In this study, benchmark analysis is carried out for a stainless steel pipe with a circumferential through-wall crack subjected to four-point bending loading. Eight solutions obtained by using five finite element programs are compared with each other. Good agreement is obtained between the solutions on the deformation characteristics as well as fracture mechanics parameters. It is found through this study that the influence of the difference in the solution technique is generally small. (author)

  4. Mechanical Behaviour of 3D Multi-layer Braided Composites: Experimental, Numerical and Theoretical Study

    Science.gov (United States)

    Deng, Jian; Zhou, Guangming; Ji, Le; Wang, Xiaopei

    2017-12-01

    Mechanical properties and failure mechanisms of a newly designed 3D multi-layer braided composites are evaluated by experimental, numerical and theoretical studies. The microstructure of the composites is introduced. The unit cell technique is employed to address the periodic arrangement of the structure. The volume averaging method is used in theoretical solutions while FEM with reasonable periodic boundary conditions and meshing technique in numerical simulations. Experimental studies are also conducted to verify the feasibility of the proposed models. Predicted elastic properties agree well with the experimental data, indicating the feasibility of the proposed models. Numerical evaluation is more accurate than theoretical assessment. Deformations and stress distributions of the unit cell under tension shows displacement and traction continuity, guaranteeing the rationality of the applied periodic boundary conditions. Although compression and tension modulus are close, the compressive strength only reaches 70% of the tension strength. This indicates that the composites can be weakened in compressive loading. Additionally, by analysing the micrograph of fracture faces and strain-stress curves, a brittle failure mechanism is observed both in composites under tension and compression.

  5. Study on the mechanism and efficiency of simulated annealing using an LP optimization benchmark problem - 113

    International Nuclear Information System (INIS)

    Qianqian, Li; Xiaofeng, Jiang; Shaohong, Zhang

    2010-01-01

    Simulated Annealing Algorithm (SAA) for solving combinatorial optimization problems is a popular method for loading pattern optimization. The main purpose of this paper is to understand the underlying search mechanism of SAA and to study its efficiency. In this study, a general SAA that employs random pair exchange of fuel assemblies to search for the optimum fuel Loading Pattern (LP) is applied to an exhaustively searched LP optimization benchmark problem. All the possible LPs of the benchmark problem have been enumerated and evaluated via the use of the very fast and accurate Hybrid Harmonics and Linear Perturbation (HHLP) method, such that the mechanism of SA for LP optimization can be explicitly analyzed and its search efficiency evaluated. The generic core geometry itself dictates that only a small number LPs can be generated by performing random single pair exchanges and that the LPs are necessarily mostly similar to the initial LP. This phase space effect turns out to be the basic mechanism in SAA that can explain its efficiency and good local search ability. A measure of search efficiency is introduced which shows that the stochastic nature of SAA greatly influences the variability of its search efficiency. It is also found that using fuel assembly k-infinity distribution as a technique to filter the LPs can significantly enhance the SAA search efficiency. (authors)

  6. Explore the reaction mechanism of the Maillard reaction: a density functional theory study.

    Science.gov (United States)

    Ren, Ge-Rui; Zhao, Li-Jiang; Sun, Qiang; Xie, Hu-Jun; Lei, Qun-Fang; Fang, Wen-Jun

    2015-05-01

    The mechanism of Maillard reaction has been investigated by means of density functional theory calculations in the gaseous phase and aqueous solution. The Maillard reaction is a cascade of consecutive and parallel reaction. In the present model system study, glucose and glycine were taken as the initial reactants. On the basis of previous experimental results, the mechanisms of Maillard reaction have been proposed, and the possibility for the formation of different compounds have been evaluated through calculating the relative energy changes for different steps of reaction under different pH conditions. Our calculations reveal that the TS3 in Amadori rearrangement reaction is the rate-determining step of Maillard reaction with the activation barriers of about 66.7 and 68.8 kcal mol(-1) in the gaseous phase and aqueous solution, respectively. The calculation results are in good agreement with previous studies and could provide insights into the reaction mechanism of Maillard reaction, since experimental evaluation of the role of intermediates in the Maillard reaction is quite complicated.

  7. Using Computational and Mechanical Models to Study Animal Locomotion

    Science.gov (United States)

    Miller, Laura A.; Goldman, Daniel I.; Hedrick, Tyson L.; Tytell, Eric D.; Wang, Z. Jane; Yen, Jeannette; Alben, Silas

    2012-01-01

    Recent advances in computational methods have made realistic large-scale simulations of animal locomotion possible. This has resulted in numerous mathematical and computational studies of animal movement through fluids and over substrates with the purpose of better understanding organisms’ performance and improving the design of vehicles moving through air and water and on land. This work has also motivated the development of improved numerical methods and modeling techniques for animal locomotion that is characterized by the interactions of fluids, substrates, and structures. Despite the large body of recent work in this area, the application of mathematical and numerical methods to improve our understanding of organisms in the context of their environment and physiology has remained relatively unexplored. Nature has evolved a wide variety of fascinating mechanisms of locomotion that exploit the properties of complex materials and fluids, but only recently are the mathematical, computational, and robotic tools available to rigorously compare the relative advantages and disadvantages of different methods of locomotion in variable environments. Similarly, advances in computational physiology have only recently allowed investigators to explore how changes at the molecular, cellular, and tissue levels might lead to changes in performance at the organismal level. In this article, we highlight recent examples of how computational, mathematical, and experimental tools can be combined to ultimately answer the questions posed in one of the grand challenges in organismal biology: “Integrating living and physical systems.” PMID:22988026

  8. Study of the static airtightness mechanisms of metal seals

    International Nuclear Information System (INIS)

    Tlili, A.

    2013-01-01

    The thesis aims to better understand the sealing mechanisms in contact at the interface between a metal gasket and clamps. The proposed approach is based on the development of a numerical model of the clamping seal by incorporating the laws' behavior of materials that will be determined by micro instrumented indentation testing. This model is particularly interested in identifying ways of providing the fluid leak to be sealed and to determine leakage rates resulting from the identified paths, as well as the evolution of the conductance of the interface over time. Particular attention will be paid to the roughness of the surfaces, changing leak paths at different levels depending on the tightening of the seal and gas flow rates in the different types of defects. The study was conducted in Pierrelatte's Sealing laboratory that develops metal seals for the aerospace, nuclear and scientific research. The thesis focuses on real surfaces and was supplemented by measurements of helium leaks using a press which applies different loads at different gas pressures and different roughness. (author) [fr

  9. Studies on mechanisms of the laser particle acceleration

    International Nuclear Information System (INIS)

    Aurand, Bastian

    2012-01-01

    Within the last decade, many developments towards higher energies and particle numbers paved the way of particle acceleration performed by high intensity laser systems. Up to now, the process of a field-induced acceleration process (Target-Normal-Sheath-Acceleration (TNSA)) is investigated the most. Acceleration occurs as a consequence of separation of charges on a surface potential. Here, the broad energy spectrum is a problem not yet overcome although many improvements were achieved. Calculations for intensities higher than 10 20..21 W/cm 2 give hint that Radiation-Pressure-Acceleration (RPA) may lead to a sharper, monoenergetic energy spectrum. Within the framework of this thesis, the investigation of the acceleration mechanism is studied experimentally in the intensity range of 10 19 W/cm 2 . Suitable targets were developed and applied for patent. A broad range of parameters was scanned by means of high repetition rates together with an adequate laser system to provide high statistics of several thousands of shots, and the dependence of target material, intensity, laser polarisation and pre plasma-conditions was verified. Comparisons with 2-d numeric simulations lead to a model of the acceleration process which was analyzed by several diagnostic methods, giving clear evidence for a new, not field-induced acceleration process. In addition, a system for a continuous variation of the polarization based on reflective optics was developed in order to overcome the disadvantages of retardation plates, and their practicability of high laser energies can be achieved.

  10. Electron microscopy studies of activation mechanisms in hydrotreating catalysis

    DEFF Research Database (Denmark)

    Dahl-Petersen, Christian

    The aim of this work is to remedy the limited fundamental insight that exists in terms of the activation and formation of hydrotreating catalysts utilized in industrial oil refining of crude oil. This is done through numerous studies of the conversion of industrially relevant molybdenum oxide...... larger amount of formed MoS2. MoS2 forms in one of two conformations of the two-dimensional atomic structure that is either in an orientation parallel or perpendicular to the nanoparticle surface. Both the initial growth of MoS2 and the subsequent formation of multi-layered structures is addressed....... This shows that initial growth tends to form an apparent bond between the MoO2 surface and the MoS2 edge and that the layer size increases through coalescence. For multi-layered structures, it is found that MoS2 layers grow through a layer-under-layer mechanism, where defects in the outer layers enable...

  11. Experimental Study on Basic Mechanical Properties of BFRP Bars

    Science.gov (United States)

    Fan, Xiaochun; Xu, Ting; Zhou, Zhengrong; Zhou, Xun

    2017-10-01

    Basalt Fiber Reinforced Polymer (BFRP) bars have the advantages of corrosion resistance, high strength, light weight, good dielectric properties, and they are new type of green reinforced alternative material. In order to determine the mechanical properties of BFRP bars, the tensile strength of basalt fiber bars was necessary to be studied. The diameters of the basalt fiber bars were compared by means of uniaxial tensile test in this article. Then the stress-strain curve can be drawn out. The results show that the stress - strain curve of BFRP bars present straight line relation, and there is no sign before failure; there is no yield platform on the stress-strain curve of BFRP bars, which are typical brittle material;the tensile strength of BFRP bars is about 3 times higher than that of ordinary steel bars. and the elastic modulus is about 1/5 of that of ordinary steel; the ultimate tensile strength of BFRP bars varies little with the increase of diameter, but there exist some differences in modulus values.

  12. Cytokine modulation by glucocorticoids: mechanisms and actions in cellular studies.

    Science.gov (United States)

    Brattsand, R; Linden, M

    1996-01-01

    Glucocorticoids inhibit the expression and action of most cytokines. This is part of the in vivo feed-back system between inflammation-derived cytokines and CNS-adrenal produced corticosteroids with the probable physiological relevance to balance parts of the host defence and anti-inflammatory systems of the body. Glucocorticoids modulate cytokine expression by a combination of genomic mechanisms. The activated glucocorticoid-receptor complex can (i) bind to and inactivate key proinflammatory transcription factors (e.g. AP-1, NF kappa B). This takes place at the promotor responsive elements of these factors, but has also been reported without the presence of DNA; (ii) via glucocorticoid responsive elements (GRE), upregulate the expression of cytokine inhibitory proteins, e.g. I kappa B, which inactivates the transcription factor NF kappa B and thereby the secondary expression of a series of cytokines; (iii) reduce the half-life time and utility of cytokine mRNAs. In studies with triggered human blood mononuclear cells in culture, glucocorticoids strongly diminish the production of the 'initial phase' cytokines IL-1 beta and TNF-alpha and the 'immunomodulatory' cytokines IL-2, IL-3, IL-4, IL-5, IL-10, IL-12 and IFN-gamma, as well as of IL-6, IL-8 and the growth factor GM-CSF. While steroid treatment broadly attenuates cytokine production, it cannot modulate it selectively, e.g. just the TH0, the TH1 or the TH2 pathways. The production of the 'anti-inflammatory' IL-10 is also inhibited. The exceptions of steroid down-regulatory activity on cytokine expression seem to affect 'repair phase' cytokines like TGF-beta and PDGF. These are even reported to be upregulated, which may explain the rather weak steroid dampening action on healing and fibrotic processes. Some growth factors, e.g. G-CSF and M-CSF, are only weakly affected. In addition to diminishing the production of a cytokine, steroids can also often inhibit its subsequent actions. Because cytokines work in

  13. Synthesis, Biological Evaluation, and Autophagy Mechanism of 12N-Substituted Sophoridinamines as Novel Anticancer Agents.

    Science.gov (United States)

    Bi, Chongwen; Zhang, Na; Yang, Peng; Ye, Cheng; Wang, Yanxiang; Fan, Tianyun; Shao, Rongguang; Deng, Hongbin; Song, Danqing

    2017-02-09

    A series of 12 N -substituted sophoridinamine derivatives were synthesized and evaluated for their cytotoxic activities in human HepG2 hepatoma cells. Structure-activity relationship revealed that introduction of a suitable arylidene or arylethyl at the N '-end could greatly enhance antiproliferation potency. Among them, compound 6b possessing a N '-trimethoxyphenyl methylene exhibited potent antiproliferation effect against three human tumor cell lines including HepG2, leukemia (K562), and breast cancer (HMLE), with IC 50 between 0.55 and 1.7 μM. The underlying mechanism of 6b against tumor cells is to block autophagic flux, mainly through neutralizing lysosomal acidity. Our results indicated that compound 6b is a potent lysosomal deacidification agent and is accordingly able to block autophagic flux and inhibit tumor cell growth.

  14. Evaluation of mechanical integrity for helical coil hold-down spring of PLUS7TM fuel

    International Nuclear Information System (INIS)

    Choi, Ki Sung; Kim, Yong Hwan; Kwon, Jung Tack; Kim, Kyu Tae

    2004-01-01

    Nuclear fuel assembly is subject to hydraulic forces generated by primary coolant flow during reactor operation. These forces may be sufficient to overcome the fuel assembly weight thereby allowing the fuel assembly to lift off of its support. To provide a positive hold-down margin against the upward coolant flow forces, helical coil springs or leaf springs are installed in the fuel assemblies. An advanced fuel for Korean Standard Nuclear Power Plants (KSNP), PLUS7 fuel has developed to get the thermal margin increase, failure free and high seismic resistance, etc. And the new designed helical coil hold-down spring was introduced into PLUS7 fuel assembly. The purpose of this paper is to evaluate the mechanical integrity for the helical coil hold-down spring of PLUS7 fuel assembly

  15. Evaluation Research as a Mechanism for Critical Inquiry and Knowledge Construction in Architectural and Urban Education

    Directory of Open Access Journals (Sweden)

    Ashraf M. Salama

    2012-12-01

    Full Text Available This article responds to the misconceptions that continue to characterize the delivery of knowledge content in architectural courses. Based on reviewing the literature on pedagogy the paper explores the value and benefits of introducing evaluation research as a mechanism for critical inquiry and knowledge construction in theory courses in architecture and urbanism. A framework is developed and employed to demonstrate the way in which this type of learning can be incorporated.   The development and implementation of a series of in-class and off campus exercises in two different contexts reveal that structured actions and experiences help students to be in control over their learning while invigorating their understanding of the body of knowledge delivered in a typical lecture format. It firmly believed that this would offer students multiple learning opportunities while fostering their capabilities to shift from passive listeners to active learners and from knowledge consumers to knowledge producers.

  16. Economic evaluation of CISM : a pilot study

    DEFF Research Database (Denmark)

    Vogt, Joachim

    2004-01-01

    air traffic controllers, critical incident stress management, CISM, critical incidents, critical incident stress, cost-benefit-analysis, economic evaluation, efficiency, return on investment......air traffic controllers, critical incident stress management, CISM, critical incidents, critical incident stress, cost-benefit-analysis, economic evaluation, efficiency, return on investment...

  17. Evaluation of fracture mechanics analyses used in RPV integrity assessment regarding brittle fracture

    International Nuclear Information System (INIS)

    Moinereau, D.; Faidy, C.; Valeta, M.P.; Bhandari, S.; Guichard, D.

    1997-01-01

    Electricite de France has conducted during these last years some experimental and numerical research programmes in order to evaluate fracture mechanics analyses used in nuclear reactor pressure vessels structural integrity assessment, regarding the risk of brittle fracture. These programmes included cleavage fracture tests on large scale cladded specimens containing subclad flaws with their interpretations by 2D and 3D numerical computations, and validation of finite element codes for pressurized thermal shocks analyses. Four cladded specimens made of ferritic steel A508 C13 with stainless steel cladding, and containing shallow subclad flaws, have been tested in four point bending at very low temperature in order to obtain cleavage failure. The specimen failure was obtained in each case in base metal by cleavage fracture. These tests have been interpreted by two-dimensional and three-dimensional finite element computations using different fracture mechanics approaches (elastic analysis with specific plasticity corrections, elastic-plastic analysis, local approach to cleavage fracture). The failure of specimens are conservatively predicted by different analyses. The comparison between the elastic analyses and elastic-plastic analyses shows the conservatism of specific plasticity corrections used in French RPV elastic analyses. Numerous finite element calculations have also been performed between EDF, CEA and Framatome in order to compare and validate several fracture mechanics post processors implemented in finite element programmes used in pressurized thermal shock analyses. This work includes two-dimensional numerical computations on specimens with different geometries and loadings. The comparisons show a rather good agreement on main results, allowing to validate the finite element codes and their post-processors. (author). 11 refs, 24 figs, 3 tabs

  18. The recognition and evaluation of patterns of compensatory injury in patients with mechanical hip pain.

    Science.gov (United States)

    Hammoud, Sommer; Bedi, Asheesh; Voos, James E; Mauro, Craig S; Kelly, Bryan T

    2014-03-01

    In active individuals with femoroacetabular impingement (FAI), the resultant reduction in functional range of motion leads to high impaction loads at terminal ranges. These increased forces result in compensatory effects on bony and soft tissue structures within the hip joint and hemipelvis. An algorithm is useful in evaluating athletes with pre-arthritic, mechanical hip pain and associated compensatory disorders. A literature search was performed by a review of PubMed articles published from 1976 to 2013. Level 4. Increased stresses across the bony hemipelvis result when athletes with FAI attempt to achieve supraphysiologic, terminal ranges of motion (ROM) through the hip joint required for athletic competition. This can manifest as pain within the pubic joint (osteitis pubis), sacroiliac joint, and lumbosacral spine. Subclinical posterior hip instability may result when attempts to increase hip flexion and internal rotation are not compensated for by increased motion through the hemipelvis. Prominence of the anterior inferior iliac spine (AIIS) at the level of the acetabular rim can result in impingement of the anterior hip joint capsule or iliocapsularis muscle origin against the femoral head-neck junction, resulting in a distinct form of mechanical hip impingement (AIIS subspine impingement). Iliopsoas impingement (IPI) has also been described as an etiology for anterior hip pain. IPI results in a typical 3-o'clock labral tear as well as an inflamed capsule in close proximity to the overlying iliopsoas tendon. Injury in athletic pubalgia occurs during high-energy twisting activities in which abnormal hip ROM and resultant pelvic motion lead to shearing across the pubic symphysis. Failure to recognize and address concomitant compensatory injury patterns associated with intra-articular hip pathology can result in significant disability and persistent symptoms in athletes with pre-arthritic, mechanical hip pain. B.

  19. Evaluation of fracture mechanics analyses used in RPV integrity assessment regarding brittle fracture

    Energy Technology Data Exchange (ETDEWEB)

    Moinereau, D [Electricite de France, Dept. MTC, Moret-sur-Loing (France); Faidy, C [Electricite de France, SEPTEN, Villeurbanne (France); Valeta, M P [Commisariat a l` Energie Atomique, Dept. DMT, Gif-sur-Yvette (France); Bhandari, S; Guichard, D [Societe Franco-Americaine de Constructions Atomiques (FRAMATOME), 92 - Paris-La-Defense (France)

    1997-09-01

    Electricite de France has conducted during these last years some experimental and numerical research programmes in order to evaluate fracture mechanics analyses used in nuclear reactor pressure vessels structural integrity assessment, regarding the risk of brittle fracture. These programmes included cleavage fracture tests on large scale cladded specimens containing subclad flaws with their interpretations by 2D and 3D numerical computations, and validation of finite element codes for pressurized thermal shocks analyses. Four cladded specimens made of ferritic steel A508 C13 with stainless steel cladding, and containing shallow subclad flaws, have been tested in four point bending at very low temperature in order to obtain cleavage failure. The specimen failure was obtained in each case in base metal by cleavage fracture. These tests have been interpreted by two-dimensional and three-dimensional finite element computations using different fracture mechanics approaches (elastic analysis with specific plasticity corrections, elastic-plastic analysis, local approach to cleavage fracture). The failure of specimens are conservatively predicted by different analyses. The comparison between the elastic analyses and elastic-plastic analyses shows the conservatism of specific plasticity corrections used in French RPV elastic analyses. Numerous finite element calculations have also been performed between EDF, CEA and Framatome in order to compare and validate several fracture mechanics post processors implemented in finite element programmes used in pressurized thermal shock analyses. This work includes two-dimensional numerical computations on specimens with different geometries and loadings. The comparisons show a rather good agreement on main results, allowing to validate the finite element codes and their post-processors. (author). 11 refs, 24 figs, 3 tabs.

  20. Preliminary evaluation of microstructure and mechanical properties on low activation ferritic steels

    International Nuclear Information System (INIS)

    Hsu, C.Y.; Lechtenberg, T.A.

    1985-01-01

    Radioactive waste disposal has become a primary concern for the selection of materials for the structural components for fusion reactors. One way to minimize this potential environmental problem is to use structural materials in which the induced radioactivity decays quickly to levels that allow for near-surface disposal under 10CFR61 rules. The primary objective of this work is to develop low activation ferritic steels that exhibit mechanical and physical properties approximately equivalent to the HT-9 and 9Cr-1Mo steels, but which only contain elements that would permit near-surface disposal under 10CFR61 after exposure to fusion neutrons. A preliminary evaluation of the microstructure and mechanical properties of a 9Cr-2.5W-0.3V-0.15C (GA3X) low activation ferritic steel has been performed. An optimum heat treatment condition has been defined for GA3X steel. The properties and microstructure of the quenched and tempered specimens were characterized via hardness measurement and optical metallographic observation. The hot-microhardness and ductility parameter measurements were used to estimate the tensile properties at elevated temperatures. The estimated tensile strengths of GA3X steel at elevated temperatures are comparable to both 9Cr-1Mo and the modified 9Cr-1Mo steels. These preliminary results are encouraging in that they suggest that suitable low activation alloys can be successfully produced in this ferritic alloy class

  1. Evaluation of mechanical properties of Dy123 bulk superconductors by 3-point bending tests

    International Nuclear Information System (INIS)

    Katagiri, K.; Hatakeyama, Y.; Sato, T.; Kasaba, K.; Shoji, Y.; Murakami, A.; Teshima, H.; Hirano, H.

    2006-01-01

    In order to evaluate the mechanical properties, such as Young's modulus and strength, of Dy123 bulk superconductors and those with 10 wt.% Ag 2 O, we performed 3-point bending tests at room (RT) and liquid nitrogen temperatures (LNT) using specimens cut from the bulks. The Young's modulus and the bending strength increased with decrease in temperature. In the tests loading in the direction of c-axis and ones perpendicular to it, Young's moduli were almost comparable at both RT and LNT. Although the strengths for both orientations were also comparable at LNT, those at RT were different. Young's moduli loaded in the direction of c-axis for Ag 2 O added bulk specimens, 127 GPa in average at RT, were almost comparable to those without Ag 2 O, and 134 GPa at LNT, were slightly lower than those without Ag 2 O. On the other hand, the strengths at both RT and LNT were enhanced by 20% by the Ag addition. The mechanical properties of Dy123 bulks without Ag 2 O were compared with those of Y123 bulks obtained previously. The Young's modulus for loading in the direction of c-axis was slightly lower, and the strength was comparable to those in Y123 bulks, respectively

  2. J evaluation by simplified method for cracked pipes under mechanical loading

    International Nuclear Information System (INIS)

    Lacire, M.H.; Michel, B.; Gilles, P.

    2001-01-01

    The integrity of structures behaviour is an important subject for the nuclear reactor safety. Most of assessment methods of cracked components are based on the evaluation of the parameter J. However to avoid complex elastic-plastic finite element calculations of J, a simplified method has been jointly developed by CEA, EDF and Framatome. This method, called Js, is based on the reference stress approach and a new KI handbook. To validate this method, a complete set of 2D and 3D elastic-plastic finite element calculations of J have been performed on pipes (more than 300 calculations are available) for different types of part through wall crack (circumferential or longitudinal); mechanical loading (pressure, bending moment, axial load, torsion moment, and combination of these loading); different kind of materials (austenitic or ferritic steel). This paper presents a comparison between the simplified assessment of J and finite element results on these configurations for mechanical loading. Then, validity of the method is discussed and an applicability domain is proposed. (author)

  3. Fabrication and mechanical evaluation of hydroxyapatite/oxide nano-composite materials.

    Science.gov (United States)

    Mohamed, Khaled R; Beherei, Hanan H; El Bassyouni, Gehan T; El Mahallawy, Nahed

    2013-10-01

    In the current study, the semiconducting metal oxides such as nano-ZnO and SiO2 powders were prepared via sol-gel technique and conducted on nano-hydroxyapatite (nHA) which was synthesized by chemical precipitation. The properties of fabricated nano-structured composites containing different ratios of HA, ZnO and SiO2 were examined using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM) and transmission electron microscope (TEM) techniques. The effect of the variation of ratios between the three components on mechanical, microstructure and in-vitro properties was assessed to explore the possibility of enhancing these properties. The results proved that the mechanical properties exhibited an increment with increasing the ZnO content at the extent of HA. In-vitro study proved the formation and nucleation of apatite onto the surface of the fabricated composites after one week of immersion. It is concluded that HA composites containing SiO2 or SiO2/ZnO content had a suitable mechanical properties and ability to form apatite particles onto the composite surface. Based on bioactivity behavior, Si-HA is more bioactive than pure hydroxyapatite and nano-arrangements will provide an interface for better bone formation. Therefore, these nano-composites will be promising as bone substitutes especially in load bearing sites. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Roentgencinematographic studies on the mechanics of the tempero-mandibular joint

    International Nuclear Information System (INIS)

    Gernet, W.; Puff, A.; Steinkraus-Maatz, C.

    1978-01-01

    Investigations of the articular mechanics of the tempero-mandibular joint are an important element in gnathology. Graphically recorded movements of the condylus obtained by extra-oral mechanical aids, only give information about the projections of the articulatory pathways. Only roentgencinematography allows a profound study of the articular mechanics. The movements of the condylus can be analysed directly without interference. Studies on condylar pathways evaluated by roentgencinematography from waerers of full dentures who received two sets of dentures which fitted after different jaw relation determinations, confirmed that the movement of the condylus is controlled by neuromuscular mechanism. The condylar pathway changes after removal of the dentures. The fitting of different dentures in a healthy stomatognatic system had no effect on the course of the pathway. In neuromuscular disorders the fitting of a full denture which can be made corresponding to the functional anatomical concept reflecting a suitable jaw relation determination according to Gerber, allows the articulation pathway to be altered. A therapeutic re-orientation of the pathological reflexes makes the improvement of the discomfort possible. (orig.) [de

  5. Mechanism of oil-pulling therapy -In vitro study

    Directory of Open Access Journals (Sweden)

    Sharath Asokan

    2011-01-01

    Conclusion: The myth that the effect of oil-pulling therapy on oral health was just a placebo effect has been broken and there are clear indications of possible saponification and emulsification process, which enhances its mechanical cleaning action.

  6. Evaluation of mechanically treated cerium (IV) oxides as corrosion inhibitors for galvanized steel

    Energy Technology Data Exchange (ETDEWEB)

    Deflorian, F., E-mail: flavio.deflorian@ing.unitn.it [Department of Materials Engineering and Industrial Technology, University of Trento, Via Mesiano 77, 38123 Trento (Italy); Fedel, M.; Rossi, S. [Department of Materials Engineering and Industrial Technology, University of Trento, Via Mesiano 77, 38123 Trento (Italy); Kamarchik, P. [PPG Industries, Coatings Innovation Center, 4325 Rosanna Drive, Allison Park, PA 15101 (United States)

    2011-09-30

    The use of cerium salts as corrosion inhibitors for hot dip galvanized steel has been object of a numerous studies in the last few years. The role of cerium ions as corrosion inhibitors was proved: cerium is able to block the cathodic sites of the metal, forming insoluble hydroxides and oxides on the zinc surface. This fact leads to a dramatic decrease of the cathodic current densities and, therefore, to a reduction the overall corrosion processes. On the other hand, the potential of cerium oxides as corrosion inhibitors was also proposed. However, the real effectiveness of this kind of anticorrosive pigments has not been clarified yet. In this work cerium (IV) oxides are considered as corrosion inhibitors for galvanized steel. The corrosion inhibition mechanism of mechanically treated (milled) CeO{sub 2} alone and in combination with milled SiO{sub 2} nanoparticles was investigated. For this purpose milled CeO{sub 2}, CeO{sub 2} and SiO{sub 2} milled together and milled SiO{sub 2} particles were studied as corrosion inhibitors in water solution. Therefore, the different mechanically treated particles were dispersed in 0.1 M NaCl solution to test their effectiveness as corrosion inhibitors for galvanized steel. The galvanized steel was immersed in the different solutions and the corrosion inhibition efficiency of the different particles was measured by means of electrochemical techniques. For this purpose, electrochemical impedance spectroscopy (EIS) measurements were carried out, monitoring the evolution of the corrosion processes occurring at the metal surface with the immersion time in the solution. The effect of the different pigments was also investigated by carrying out anodic and cathodic polarization measurements. The polarization curves were acquired under conditions of varied pH. The experimental measurements suggest that the mechanical treatment performed on the SiO{sub 2} and CeO{sub 2} particles promote the formation of an effective corrosion pigment

  7. Evaluation of Mechanical Properties of MWCNT / Nanoclay Reinforced Aluminium alloy Metal Matrix Composite

    Science.gov (United States)

    Ratna Kumar, P. S. Samuel; Robinson Smart, D. S.; Alexis, S. John

    2018-04-01

    Aluminium alloy 5083 (AA5083) is a widely used material in aerospace, marine, defence and structural applications were mechanical and corrosion resistance property plays a vital role. For the present work, MWCNT / Nanoclay (montmorillonite (MMT) K10) mixed with AA5083 for different composition in weight percentage to enhance the mechanical property. Semi-solid state casting method (Compo-casting) was used to fabricate the composite materials. By using Field-emission scanning electron microscope (FESEM) the uniform dispersion of the reinforcement and microstructure were studied. Finally, the addition of Nanoclay shows decrease in tensile strength compared to the AA5083 / MWCNT composites and hardness value of the composites (AA5083 / MWCNT and AA5083 / Nanoclay) was found to increase significantly.

  8. Pessimistic Determination of Mechanical Conditions and Micro/macroeconomic Evaluation of Mine Pillar Replacement

    Science.gov (United States)

    Chen, Qingfa; Zhao, Fuyu

    2017-12-01

    Numerous pillars are left after mining of underground mineral resources using the open stope method or after the first step of the partial filling method. The mineral recovery rate can, however, be improved by replacement recovery of pillars. In the present study, the relationships among the pillar type, minimum pillar width, and micro/macroeconomic factors were investigated from two perspectives, namely mechanical stability and micro/macroeconomic benefit. Based on the mechanical stability formulas for ore and artificial pillars, the minimum width for a specific pillar type was determined using a pessimistic criterion. The microeconomic benefit c of setting an ore pillar, the microeconomic benefit w of artificial pillar replacement, and the economic net present value (ENPV) of the replacement process were calculated. The values of c and w were compared with respect to ENPV, based on which the appropriate pillar type and economical benefit were determined.

  9. Evaluation of the electron beam radiation effects on the mechanical properties of the polypropylene

    International Nuclear Information System (INIS)

    Souza, Clecia M.; Moura, Esperidiana A.B.; Chinellato, Anne

    2009-01-01

    This paper studied the electron beam radiation effects on the mechanical properties of the polypropylene (PP) resin. The PP resin was submitted to 150-250 kGy radiation dose, at the dose rate of 14 kGy/s, room temperature and presence of air, using a 1.5 MeV electron accelerator. After the irradiation, the irradiated and non irradiated resin samples were submitted to the mechanical testes of traction resistance and impact Izod resistance. The results shown that the traction resistance at drainage of PP samples have not experienced significant modifications (p < 0.05) after the irradiation. However, the original PP rupture resistance (non irradiated samples) presented a gain up to 100 % as function of the applied radiation dose; the percentage of deformation in the rupture presented a reduction up to 65 % and the Izod impact resistance presented a reduction up to 70 % with the increase of the radiation dose (p < 0.05)

  10. Evaluation of Microstructure and Mechanical Properties in Dissimilar Austenitic/Super Duplex Stainless Steel Joint

    Science.gov (United States)

    Rahmani, Mehdi; Eghlimi, Abbas; Shamanian, Morteza

    2014-10-01

    To study the effect of chemical composition on microstructural features and mechanical properties of dissimilar joints between super duplex and austenitic stainless steels, welding was attempted by gas tungsten arc welding process with a super duplex (ER2594) and an austenitic (ER309LMo) stainless steel filler metal. While the austenitic weld metal had vermicular delta ferrite within austenitic matrix, super duplex stainless steel was mainly comprised of allotriomorphic grain boundary and Widmanstätten side plate austenite morphologies in the ferrite matrix. Also the heat-affected zone of austenitic base metal comprised of large austenite grains with little amounts of ferrite, whereas a coarse-grained ferritic region was observed in the heat-affected zone of super duplex base metal. Although both welded joints showed acceptable mechanical properties, the hardness and impact strength of the weld metal produced using super duplex filler metal were found to be better than that obtained by austenitic filler metal.

  11. Comparative study of the mechanical properties from different polycarbonates

    International Nuclear Information System (INIS)

    Terence, M.C.; Miranda, A.; Guedes, S.M.L.; Sciani, V.

    1995-01-01

    The polycarbonates (PC) with molecular weight 22000 and 27000 g/mol fabricated by Policarbonatos do Brasil S.A., as irradiated by γ rays with doses between 0 and 300 kGy in presence of air at room temperature. The effects in the mechanical properties of PC were investigated using an INSTRON dynamometer. The results showed that both PC have good mechanical stability. (author). 6 refs, 2 figs

  12. Comparison of leaching tests and study of leaching mechanisms

    International Nuclear Information System (INIS)

    Amarantos, S.G.; Papadokostaki, K.G.; Petropoulos, J.H.

    1985-10-01

    The present work is concerned first with the study of certain aspects of the leaching kinetics of Cs + and Sr ++ embedded in cement, as Cs 2 SO 4 and SrSO 4 , and in particular: (a) the comparative evaluation of leaching in (i) stagnant, (ii) stirred and (iii) continuously flowing (modified Soxhlet) water, (b) the effect of atmospheric CO 2 on elution, (c) the effect of temperature changes during leaching. Secondly, model kinetic studies were carried out using cellulose acetate incorporating SrSO 4 , CaSO 4 or NaCl. The main results obtained were: (1) Cs leaching rates were not significantly affected by the leaching method or by the presence of atmospheric CO 2 . The embedded Cs exists in relatively easily leachable and less rapidly leachable (most probably located within the gel regions) forms. (2) Elution of Sr is retarded by stagnant and infrequently renewed leachant (method (i)) and by the presence of atmospheric CO 2 ; leaching method (iii), which tends to minimize both of these effects, gave the highest elution rates. (3) The observed elution kinetics in the case of cellulose acetate-CaSO 4 or SrSO 4 conform to the Higuchi model, but a more elaborate theory is needed for the cellulose acetate-NaCl system. (author)

  13. Effects of flunixin meglumine on experimental tendon wound healing: A histopathological and mechanical study in rabbits

    Directory of Open Access Journals (Sweden)

    Mehdi Behfar

    2014-12-01

    Full Text Available Tendons are frequently targets of injury in sports and work. Whether nonsteroidal anti-inflammatory drugs (NSAIDs have beneficial effects on tendon healing is still a matter of debate. This study was conducted to evaluate effects of flunixin meglumine (FM on tendon healing after experimentally induced acute trauma. Twenty eight adult male New Zealand White rabbits were subjected to complete transection of deep digital flexor tendons followed by suture placement. Treatment group received intramuscular injection of FM for three days, and controls received placebo. Subsequently, cast immobilization was continued for two weeks. Animals were sacrificed four weeks after surgery and tissue samples were taken. The histological evaluations revealed improved structural characteristics of neotendon formation including fibrillar linearity, fibrillar continuity and neovascularization in treatment group compared to those of controls (p 0.05. Mechanical evaluation revealed significant increase in load-related material properties including ultimate load, yield load, energy absorption and ultimate stress in treatment group compared to those of control group (p 0.05. The present study showed that intramuscular injection of FM resulted in improved structural and mechanical properties of tendon repairs and it could be an effective treatment for acute tendon injuries like severance and laceration.

  14. An approximate approach to quantum mechanical study of biomacromolecules

    Science.gov (United States)

    Chen, Xihua

    This thesis summarizes the author's major work in Prof. John Z.H. Zhang's Threoretical Chemistry research group. In Chapter 1, we present a general description of MFCC (molecular fractionation with conjugated caps) method that has been developed in this group to treat biomacromolecules in a divide-and-conquer fashion. Then we give in detail a computational study of MFCC application to peptide/protein that contains disulfide bonds. Continued on the basis of previous MFCC tests, this study provides another numerical support for the accuracy of the MFCC approach to full quantum mechanical calculation of protein/peptide-small molecule interaction. In Chapter 2, we further develop the MFCC scheme for quantum mechanical computation of DNA-ligand interaction energy. We study three oligonuclear acid interaction systems: dinucleotide dCG/water, trinucleotide dCGT/water and a Watson-Crick paired DNA segment dCGT/dGCA. The MFCC interaction energies are found to be in excellent agreement with the corresponding results obtained from the full system ab initio calculations. This study is an exemplification of the application of the general MFCC approach to biomacromolecules. In Chapter 3, firstly, a MFCC-downhill simplex method is proposed to study binding structures of ligands (atoms, ions, or small molecules) in large molecular complex systems. This method employs the MFCC approach to compute the interaction energy-structure relation of the system and implements the downhill simplex algorithm for structural optimization. Secondly, this method is numerically tested on a system of [KCp(18-crown-6)], as a simplest monatomic case study, to optimize the binding position of the potassium cation in a fixed coordination Cp and 18-crown-6 coordinating sphere. The result of the MFCC-downhill simplex optimization shows good agreement with both the crystal structure and with the full-system downhill simplex optimized structure. The effects of the initial structure of the simplex and of the

  15. Fabrication and mechanical evaluation of hydroxyapatite/oxide nano-composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, Khaled R., E-mail: Kh_rezk1966@yahoo.com [Biomaterials Dept., National Research Centre, El-Behoos St., Cairo (Egypt); Beherei, Hanan H. [Biomaterials Dept., National Research Centre, El-Behoos St., Cairo (Egypt); Physics Dept., Faculty of Science, El-Taif University (Saudi Arabia); El Bassyouni, Gehan T. [Biomaterials Dept., National Research Centre, El-Behoos St., Cairo (Egypt); Medical Physics Dept., Faculty of Medicine, El-Taif University (Saudi Arabia); El Mahallawy, Nahed [Design and Production Engineering Department, Faculty of Engineering, Ain Shams University on secondment to the German University in Cairo (Egypt)

    2013-10-15

    In the current study, the semiconducting metal oxides such as nano-ZnO and SiO{sub 2} powders were prepared via sol–gel technique and conducted on nano-hydroxyapatite (nHA) which was synthesized by chemical precipitation. The properties of fabricated nano-structured composites containing different ratios of HA, ZnO and SiO{sub 2} were examined using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM) and transmission electron microscope (TEM) techniques. The effect of the variation of ratios between the three components on mechanical, microstructure and in-vitro properties was assessed to explore the possibility of enhancing these properties. The results proved that the mechanical properties exhibited an increment with increasing the ZnO content at the extent of HA. In-vitro study proved the formation and nucleation of apatite onto the surface of the fabricated composites after one week of immersion. It is concluded that HA composites containing SiO{sub 2} or SiO{sub 2}/ZnO content had a suitable mechanical properties and ability to form apatite particles onto the composite surface. Based on bioactivity behavior, Si-HA is more bioactive than pure hydroxyapatite and nano-arrangements will provide an interface for better bone formation. Therefore, these nano-composites will be promising as bone substitutes especially in load bearing sites. - Graphical abstract: Nano-structures of (a) HA, (b) ZnO and (c) SiO{sub 2} powders. Highlights: • The nano-structured composites containing different ratios of HA, ZnO and SiO{sub 2} were prepared. • ZnO helps improve the mechanical properties of HA composites. • SiO{sub 2} helps improve the bioactivity of HA composites.

  16. Mechanical Elongation of the Small Intestine: Evaluation of Techniques for Optimal Screw Placement in a Rodent Model

    Directory of Open Access Journals (Sweden)

    P. A. Hausbrandt

    2013-01-01

    Full Text Available Introduction. The aim of this study was to evaluate techniques and establish an optimal method for mechanical elongation of small intestine (MESI using screws in a rodent model in order to develop a potential therapy for short bowel syndrome (SBS. Material and Methods. Adult female Sprague Dawley rats (n=24 with body weight from 250 to 300 g (Σ=283 were evaluated using 5 different groups in which the basic denominator for the technique involved the fixation of a blind loop of the intestine on the abdominal wall with the placement of a screw in the lumen secured to the abdominal wall. Results. In all groups with accessible screws, the rodents removed the implants despite the use of washers or suits to prevent removal. Subcutaneous placement of the screw combined with antibiotic treatment and dietary modifications was finally successful. In two animals autologous transplantation of the lengthened intestinal segment was successful. Discussion. While the rodent model may provide useful basic information on mechanical intestinal lengthening, further investigations should be performed in larger animals to make use of the translational nature of MESI in human SBS treatment.

  17. Evaluation of the influence of mechanical activation on physical and chemical properties of municipal solid waste incineration sludge.

    Science.gov (United States)

    Caprai, V; Florea, M V A; Brouwers, H J H

    2018-06-15

    Despite numerous studies concerning the application of by-products in the construction field, municipal solid waste incineration (MSWI) residues are not widely used as secondary building materials. In some European countries, washing treatment to the full bottom ash (BA) fraction (0-32 mm) is applied, isolating more contaminated particles, smaller than 0.063 mm. Therefore, a MWSI sludge is produced, having a high moisture content, and thus a limited presence of soluble species. In order to enhance its performance as building material, here, dry mechanical activation is applied on MSWI sludge. Thereafter, a reactivity comparison between reference BA and untreated and treated MSWI sludge is provided, evaluating their behaviour in the presence of cement and their pozzolanic activity. Moreover, the mechanical performances, as 25% substitution of Portland cement (PC) are assessed, based on the EN 450. Mechanical activation enhances MSWI sludge physically due to the improved particle morphology and packing. Chemically, the hydration degree of PC is enhanced by the MSWI sludge by ≈25%. The milling treatment proved to be beneficial to the residues performances in the presence of PC, providing 32% higher strength than untreated sample. Environmentally, the compliance with the unshaped material legislation is successfully verified, according to the Soil Quality Decree. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Theoretical study of coupling mechanisms between oxygen diffusion, chemical reaction, mechanical stresses in a solid-gas reactive system

    International Nuclear Information System (INIS)

    Creton, N.; Optasanu, V.; Montesin, T.; Garruchet, S.

    2008-01-01

    This paper offers a study of oxygen dissolution into a solid, and its consequences on the mechanical behaviour of the material. In fact, mechanical strains strongly influence the oxidation processes and may be, in some materials, responsible for cracking. To realize this study, mechanical considerations are introduced into the classical diffusion laws. Simulations were made for the particular case of uranium dioxide, which undergoes the chemical fragmentation. According to our simulations, the hypothesis of a compression stress field into the oxidised UO 2 compound near the internal interface is consistent with some oxidation mechanisms of oxidation experimentally observed. More generally, this work will be extended to the simulation to an oxide layer growth on a metallic substrate. (authors)