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Sample records for fractured roman glass

  1. Analytical Plan for Roman Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Strachan, Denis M.; Buck, Edgar C.; Mueller, Karl T.; Schwantes, Jon M.; Olszta, Matthew J.; Thevuthasan, Suntharampillai; Heeren, Ronald M.

    2011-01-01

    Roman glasses that have been in the sea or underground for about 1800 years can serve as the independent “experiment” that is needed for validation of codes and models that are used in performance assessment. Two sets of Roman-era glasses have been obtained for this purpose. One set comes from the sunken vessel the Iulia Felix; the second from recently excavated glasses from a Roman villa in Aquileia, Italy. The specimens contain glass artifacts and attached sediment or soil. In the case of the Iulia Felix glasses quite a lot of analytical work has been completed at the University of Padova, but from an archaeological perspective. The glasses from Aquileia have not been so carefully analyzed, but they are similar to other Roman glasses. Both glass and sediment or soil need to be analyzed and are the subject of this analytical plan. The glasses need to be analyzed with the goal of validating the model used to describe glass dissolution. The sediment and soil need to be analyzed to determine the profile of elements released from the glass. This latter need represents a significant analytical challenge because of the trace quantities that need to be analyzed. Both pieces of information will yield important information useful in the validation of the glass dissolution model and the chemical transport code(s) used to determine the migration of elements once released from the glass. In this plan, we outline the analytical techniques that should be useful in obtaining the needed information and suggest a useful starting point for this analytical effort.

  2. Analysis of Roman glass from Albania by PIXE–PIGE method

    International Nuclear Information System (INIS)

    Šmit, Ž.; Tartari, F.; Stamati, F.; Vevecka Priftaj, A.; Istenič, J.

    2013-01-01

    A series of 31 Roman glasses dated to the 1st–4th c. AD from the present Albania was analyzed by the combined PIXE–PIGE method. The analysis shows typical natron-based glass of the Roman period, though statistical treatment using principal component analysis and bivariate plots reveals four distinct groups, which are qualified by increased levels of potassium, magnesium and titanium–manganese–iron oxides, respectively. MgO content may exceed 2% and reach the level commonly accepted for halophytic plant-ash glass. The groups are formed on account of mineral impurities in the sand, which gives support to the thesis of multiple production centers of raw glass in the imperial age

  3. Change in silica sources in Roman and post-Roman glass

    International Nuclear Information System (INIS)

    Aerts, A.; Velde, B.; Janssens, K.; Dijkman, W.

    2003-01-01

    Although Roman and post-Empire glasses found in Europe are reputed to have a very constant composition and hence source of components, it appears that some 4-5th century and later specimens show evidence of a different source of silica (sand) component. Zirconium and titanium are the discriminating elements. Data presented here for 278 specimens from 1st to 4th century German and Belgian samples indicate a strongly homogeneous Zr and Ti content; N: number of analyzed samples while 62 samples from Maastricht show low Zr-Ti contents from 1st to 3rd century samples while 4-5th century samples show a strong trend of concomitant Ti and Zr increase. If the high values of Zr-Ti represent a new source of silica (sand) the trend from low to high content suggests that a significant amount of low Zr-Ti glass was recycled to form these glass objects. Similar high Ti content can be seen in analysis results reported for other but not all 4-5th century samples found in northern Europe while earlier productions show typical low Ti contents. Although the fusing agent for these glasses seems to have always been natron (a mineral deposit in the Nile delta) from Hellenistic times to the 9th century, a change in the silica source, indicated by variation of the Ti and Zr content, could very well reflect the results of political instability of the 4-5th century exemplified by the fragmentation of the Roman Empire into two parts

  4. Change in silica sources in Roman and post-Roman glass

    Energy Technology Data Exchange (ETDEWEB)

    Aerts, A.; Velde, B.; Janssens, K.; Dijkman, W

    2003-04-18

    Although Roman and post-Empire glasses found in Europe are reputed to have a very constant composition and hence source of components, it appears that some 4-5th century and later specimens show evidence of a different source of silica (sand) component. Zirconium and titanium are the discriminating elements. Data presented here for 278 specimens from 1st to 4th century German and Belgian samples indicate a strongly homogeneous Zr and Ti content; N: number of analyzed samples while 62 samples from Maastricht show low Zr-Ti contents from 1st to 3rd century samples while 4-5th century samples show a strong trend of concomitant Ti and Zr increase. If the high values of Zr-Ti represent a new source of silica (sand) the trend from low to high content suggests that a significant amount of low Zr-Ti glass was recycled to form these glass objects. Similar high Ti content can be seen in analysis results reported for other but not all 4-5th century samples found in northern Europe while earlier productions show typical low Ti contents. Although the fusing agent for these glasses seems to have always been natron (a mineral deposit in the Nile delta) from Hellenistic times to the 9th century, a change in the silica source, indicated by variation of the Ti and Zr content, could very well reflect the results of political instability of the 4-5th century exemplified by the fragmentation of the Roman Empire into two parts.

  5. Change in silica sources in Roman and post-Roman glass

    Science.gov (United States)

    Aerts, A.; Velde, B.; Janssens, K.; Dijkman, W.

    2003-04-01

    Although Roman and post-Empire glasses found in Europe are reputed to have a very constant composition and hence source of components, it appears that some 4-5th century and later specimens show evidence of a different source of silica (sand) component. Zirconium and titanium are the discriminating elements. Data presented here for 278 specimens from 1st to 4th century German and Belgian samples indicate a strongly homogeneous Zr and Ti content; N: number of analyzed samples while 62 samples from Maastricht show low Zr-Ti contents from 1st to 3rd century samples while 4-5th century samples show a strong trend of concomitant Ti and Zr increase. If the high values of Zr-Ti represent a new source of silica (sand) the trend from low to high content suggests that a significant amount of low Zr-Ti glass was recycled to form these glass objects. Similar high Ti content can be seen in analysis results reported for other but not all 4-5th century samples found in northern Europe while earlier productions show typical low Ti contents. Although the fusing agent for these glasses seems to have always been natron (a mineral deposit in the Nile delta) from Hellenistic times to the 9th century, a change in the silica source, indicated by variation of the Ti and Zr content, could very well reflect the results of political instability of the 4-5th century exemplified by the fragmentation of the Roman Empire into two parts.

  6. PIXE-PIGE analysis of late roman glass fragments

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Tubio, B. [Departamento de Fisica Aplicada III, Escuela de Ingenieros, Universidad de Sevilla, Camino de los Descubrimientos s/n, 41092 Sevilla (Spain)]. E-mail: tubio@us.es; Ontalba Salamanca, M.A. [Departamento de Fisica, Escuela Politecnica, Universidad de Extremadura, Avda. de la Universidad s/n, 10071 Caceres (Spain); Ortega-Feliu, I. [Centro Nacional de Aceleradores, Universidad de Sevilla, Avda. Thomas A. Edison s/n, 41092 Sevilla (Spain); Respaldiza, M.A. [Centro Nacional de Aceleradores, Universidad de Sevilla, Avda. Thomas A. Edison s/n, 41092 Sevilla (Spain); Amores Carredano, F. [Departamento de Prehistoria y Arqueologia, Universidad de Sevilla, C/Dona Maria de Padilla s/n, 41010 Sevilla (Spain); Gonzalez-Acuna, D. [Departamento de Geografia, Historia y Filosofia, Universidad Pablo de Olavide, Ctra. de Utrera Km 1, 41013 Sevilla (Spain)

    2006-08-15

    A set of Roman glass fragments, excavated at Sevilla and dated in the 5th century A.D., has been analysed by PIXE and PIGE techniques using the external beam set-up of the 3 MV tandem Pelletron accelerator of the CNA at the University of Sevilla. Using a simple quantification method, based on the indirect charge calculation on the sample by monitoring the X-ray induced by the proton beam on the exit window, the composition of the glasses has been determined. From the obtained results, the use of soda as flux has been inferred and colouring manufacture procedures have been identified.

  7. Validation of the determination of the B isotopic composition in Roman glasses with laser ablation multi-collector inductively coupled plasma-mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Devulder, Veerle [Department of Analytical Chemistry, Ghent University, Krijgslaan 281-S12, 9000 Ghent (Belgium); Department of Earth and Environmental Sciences, Katholieke Universiteit Leuven, Celestijnenlaan 200 E-box 2408, 3001 Leuven (Belgium); Gerdes, Axel [Institute of Geoscience, Goethe Universität, Altenhoeferallee 1, 60438 Frankfurt am Main (Germany); Vanhaecke, Frank, E-mail: Frank.Vanhaecke@UGent.be [Department of Analytical Chemistry, Ghent University, Krijgslaan 281-S12, 9000 Ghent (Belgium); Degryse, Patrick [Department of Earth and Environmental Sciences, Katholieke Universiteit Leuven, Celestijnenlaan 200 E-box 2408, 3001 Leuven (Belgium)

    2015-03-01

    The applicability of laser ablation multi-collector inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS) for the determination of the B isotopic composition in Roman glasses was investigated. The δ{sup 11}B values thus obtained provide information on the natron flux used during the glass-making process. The glass samples used for this purpose were previously characterized using pneumatic nebulization (PN) MC-ICP-MS. Unfortunately, this method is time-consuming and labor-intensive and consumes some 100 mg of sample, which is a rather high amount for ancient materials. Therefore, the use of the less invasive and faster LA-MC-ICP-MS approach was explored. In this work, the results for 29 Roman glasses and 4 home-made glasses obtained using both techniques were compared to assess the suitability of LA-MC-ICP-MS in this context. The results are in excellent agreement within experimental uncertainty. No difference in overall mass discrimination was observed between the Roman glasses, NIST SRM 610 reference glass and B6 obsidian. The expanded uncertainty of the LA-MC-ICP-MS approach was estimated to be < 2‰, which is similar to that obtained upon sample digestion and PN-MC-ICP-MS measurement. - Highlights: • First use of LA-MC-ICP-MS for B isotopic analysis of ancient glass • Careful validation of LA-MC-ICP-MS approach • Similar precision & accuracy via solution MC-ICP-MS after isolation of B • Enhancement of sample throughput & reduction of sample consumption • Improved conditions for archeometric research on (pre-)Roman glass.

  8. Validation of the determination of the B isotopic composition in Roman glasses with laser ablation multi-collector inductively coupled plasma-mass spectrometry

    International Nuclear Information System (INIS)

    Devulder, Veerle; Gerdes, Axel; Vanhaecke, Frank; Degryse, Patrick

    2015-01-01

    The applicability of laser ablation multi-collector inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS) for the determination of the B isotopic composition in Roman glasses was investigated. The δ 11 B values thus obtained provide information on the natron flux used during the glass-making process. The glass samples used for this purpose were previously characterized using pneumatic nebulization (PN) MC-ICP-MS. Unfortunately, this method is time-consuming and labor-intensive and consumes some 100 mg of sample, which is a rather high amount for ancient materials. Therefore, the use of the less invasive and faster LA-MC-ICP-MS approach was explored. In this work, the results for 29 Roman glasses and 4 home-made glasses obtained using both techniques were compared to assess the suitability of LA-MC-ICP-MS in this context. The results are in excellent agreement within experimental uncertainty. No difference in overall mass discrimination was observed between the Roman glasses, NIST SRM 610 reference glass and B6 obsidian. The expanded uncertainty of the LA-MC-ICP-MS approach was estimated to be < 2‰, which is similar to that obtained upon sample digestion and PN-MC-ICP-MS measurement. - Highlights: • First use of LA-MC-ICP-MS for B isotopic analysis of ancient glass • Careful validation of LA-MC-ICP-MS approach • Similar precision & accuracy via solution MC-ICP-MS after isolation of B • Enhancement of sample throughput & reduction of sample consumption • Improved conditions for archeometric research on (pre-)Roman glass

  9. Ongoing Model Development Analyzing Glass Fracture

    DEFF Research Database (Denmark)

    Molnar, G.; Bojtar, I.; Nielsen, Jens Henrik

    2013-01-01

    Present subject deals with an ongoing experimental and numerical analysis of inplane loaded glass plates. The main goal of the investigation is to develop a hybrid – discrete and finite element – model which could follow the fracture process in annealed and in tempered glass. Measurements of the ...... an overview of the structure of the research and a summary of current status archived so far.......Present subject deals with an ongoing experimental and numerical analysis of inplane loaded glass plates. The main goal of the investigation is to develop a hybrid – discrete and finite element – model which could follow the fracture process in annealed and in tempered glass. Measurements...... of the residual stress state before failure and high-speed camera recordings of the failure are being performed in order to verify the numerical model. The primary goal of this research is to follow the overall fracture of a structural element – e.g. beam – loaded inplane. Present paper would like to give...

  10. Fracture Resistance, Surface Defects and Structural Strength of Glass

    OpenAIRE

    Rodichev, Y.M.; Veer, F.A.

    2010-01-01

    This paper poses the theory that the fracture resistance of basic float glass is dependent on it physicochemical properties and the surface defects fonned under the float glass production, glass processing and handling at the service conditions compose the aggregate basis for structural glass strength assessment. The effect of loading conditions, constructional and technological factors on the engineering strength of glass can be evaluated in certain cases using fracture mechanics with inform...

  11. Photon emission induced by brittle fracture of borosilicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Shiota, Tadashi, E-mail: tshiota@ceram.titech.ac.jp [Department of Metallurgy and Ceramic Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Sato, Yoshitaka [Department of Metallurgy and Ceramic Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Kishi, Tetsuo [Department of Chemistry and Materials Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Yasuda, Kouichi [Department of Metallurgy and Ceramic Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)

    2016-05-15

    Photon emission (PE) at wavelength ranges of 430–490 nm (B-PE), 500–600 nm (G-PE) and 610–680 nm (R-PE) caused by brittle fracture was simultaneously measured in the nanosecond-to-microsecond and millisecond time domains for two types of borosilicate glasses: Pyrex-type Tempax glass and BK7 glass. The results were compared to those for silica and soda lime glasses. The time dependence of the PE of Tempax glass was similar to that of silica glass, while the PE intensity was lower. Because Tempax glass contains both silica-rich and borate-rich amorphous phases, the PE must be mainly produced by the fracture of the silica-rich phase. Moreover, the proportion of B-PE of Tempax glass was higher than that of silica glass. This suggests that the measured B-PE might also include very weak PE caused by the fracture of the borate-rich phase. The PE time dependence of BK7 glass was similar to that of soda lime glass, which was different from the case for Tempax glass. The PE intensity of BK7 glass was slightly higher than that of soda lime glass, but much lower than that of Tempax glass. The result indicates that non-bridging oxygen in the glasses affects crack propagation behavior and reduces the PE. - Highlights: • Photon emission (PE) upon brittle fracture of borosilicate glasses was measured. • Pyrex-type Tempax and BK7 glasses showed different PE characteristics. • The rupture of Si–O bonds produces much stronger PE than that of B–O bonds. • Non-bridging oxygen in glass affects crack propagation behavior and reduces the PE.

  12. Corrosion phenomena in electron, proton and synchrotron X-ray microprobe analysis of Roman glass from Qumran, Jordan

    Science.gov (United States)

    Janssens, K.; Aerts, A.; Vincze, L.; Adams, F.; Yang, C.; Utui, R.; Malmqvist, K.; Jones, K. W.; Radtke, M.; Garbe, S.; Lechtenberg, F.; Knöchel, A.; Wouters, H.

    1996-04-01

    A series of 89 glass fragments of Roman glass are studied using electron, proton and synchrotron radiation induced X-ray emission from microscopic areas on the sample surface. The glass originates from Qumran, Jordan and was buried for 1900 years. The weathering layers that result from the extended contact with ground water have been studied, next to the trace composition of the original glass of these pieces. The latter information indicates that at Qumran, large quantities of glass objects were being used in Ancient times. Cross-sectional profiles of the glass show a complex migration behaviour of various groups of major and trace elements.

  13. Measurement of Solute Diffusion Behavior in Fractured Waste Glass Media

    International Nuclear Information System (INIS)

    Saripalli, Kanaka P.; Lindberg, Michael J.; Meyer, Philip D.

    2008-01-01

    Determination of aqueous phase diffusion coefficients of solutes through fractured media is essential for understanding and modeling contaminants transport at many hazardous waste disposal sites. No methods for earlier measurements are available for the characterization of diffusion in fractured glass blocks. We report here the use of time-lag diffusion experimental method to assess the diffusion behavior of three different solutes (Cs, Sr and Pentafluoro Benzoic Acid or PFBA) in fractured, immobilized low activity waste (ILAW) glass forms. A fractured media time-lag diffusion experimental apparatus that allows the measurement of diffusion coefficients has been designed and built for this purpose. Use of time-lag diffusion method, a considerably easier experimental method than the other available methods, was not previously demonstrated for measuring diffusion in any fractured media. Hydraulic conductivity, porosity and diffusion coefficients of a solute were experimentally measured in fractured glass blocks using this method for the first time. Results agree with the range of properties reported for similar rock media earlier, indicating that the time-lag experimental method can effectively characterize the diffusion coefficients of fractured ILAW glass media

  14. Fracture during cooling of cast borosilicate glass containing nuclear wastes

    International Nuclear Information System (INIS)

    Smith, P.K.; Baxter, C.A.

    1981-09-01

    Procedures and techniques were evaluated to mitigate thermal stress fracture in waste glass as the glass cools after casting. The two principal causes of fracture identified in small-scale testing are internal thermal stresses arising from excessive thermal gradients when cooled too fast, and shear fracturing in the surface of the glass because the stainless steel canister shrinks faster than the glass on cooling. Acoustic emission and ceramographic techniques were used to outline an annealing schedule that requires at least three weeks of controlled cooling below 550 0 C to avoid excessive thermal gradients and corresponding stresses. Fracture arising from canister interactions cannot be relieved by slow cooling, but can be eliminated for stainless steel canisters by using ceramic paper, ceramic or graphite paste linings, or by choosing a canister material with a thermal expansion coefficient comparable to, or less than, that of the glass

  15. Analysis of glass from the post-Roman settlement Tonovcov grad (Slovenia) by PIXE–PIGE and LA-ICP-MS

    Energy Technology Data Exchange (ETDEWEB)

    Šmit, Ž., E-mail: ziga.smit@fmf.uni-lj.si [Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana (Slovenia); Jožef Stefan Institute, Jamova 39, SI-1001 Ljubljana (Slovenia); Milavec, T. [Department of Archaeology, Faculty of Arts, University of Ljubljana, Zavetiška 5, SI-1000 Ljubljana (Slovenia); Fajfar, H. [Jožef Stefan Institute, Jamova 39, SI-1001 Ljubljana (Slovenia); Rehren, Th. [UCL Qatar, Education City, P.O. Box 23689, Doha (Qatar); Lankton, J.W. [UCL Institute of Archaeology, 31-34 Gordon Square, London WC1H 0PY (United Kingdom); Gratuze, B. [IRAMAT-Centre Ernest-Babelon, CNRS Université d’Orléans, 3D rue de la Ferollerie, 45071 Orléans Cedex 2 (France)

    2013-09-15

    The combined PIXE–PIGE method was used for the analysis of 43 glass fragments from the archaeological site Tonovcov grad in western Slovenia, with 10 of these additionally being analysed by LA-ICP-MS. The glass objects were attributed to the Late Antique production of the 4th–7th c. AD, with two examples of early Roman glass and three glass beads, one of them presumably of oriental origin. The analysis showed typical natron-type glass, produced in the Levantine region around the river Belus, and a few examples of HIMT glass, which could be recognized also in several other recycled objects. Only one glass bead, found in Early Medieval context, was made of the ash of halophytic plants.

  16. Thermal fracture and pump limit of Nd: glass

    International Nuclear Information System (INIS)

    Wang Mingzhe; Ma Wen; Tan Jichun; Zhang Yongliang; Li Mingzhong; Jing Feng

    2011-01-01

    Based on published fracture experiments and 3D transient finite-element analyses, and taking the first principal stress as the criterion and the Griffith crack theory to determine the critical fracture stress, a Weibull statistical model is established to predict the fracture possibility of Nd: glass with certain pump parameters. Other issues which limit the pump power are also presented. The results show that the fracture limit of laser medium depends on the optical polishing technology. For a short pulse and high energy Nd: glass laser, taking America's polishing technology in the 1990s as reference,the pump saturation limits the pump power to 18 kW/cm 2 when the repetition rate is lower than 1 Hz, while the thermal fracture limits the pump power when the repetition rate is higher than 10 Hz. (authors)

  17. Laser induced breakdown spectroscopy for analysis and characterization of degradation pathologies of Roman glasses

    International Nuclear Information System (INIS)

    Palomar, T.; Oujja, M.; García-Heras, M.; Villegas, M.A.; Castillejo, M.

    2013-01-01

    The feasibility and possibilities of laser induced breakdown spectroscopy (LIBS) in the full study of non-destructible historic glasses have been explored in the present work. Thirteen Roman glass samples, including seven entire glass beads, from the ancient town of Augusta Emerita (SW Spain) were characterized by LIBS in combination with other conventional techniques, such as scanning electron microscopy/energy dispersive X-ray spectrometry, X-ray fluorescence and ultraviolet–visible spectrophotometry. LIBS stratigraphic analysis, carried out by the application of successive laser pulses on the same spot, has been mainly targeted at characterizing particular features of non-destructible historic glasses, such as bulk chemical composition, surface degradation pathologies (dealkalinization layers and deposits), chromophores, and opacifying elements. The obtained data demonstrate that LIBS can be a useful and alternative technique for spectroscopic studies of historical glasses, especially for those conserved under burial conditions and when it deals with studying non-destructible samples. - Highlights: • Determination of chromophores and opacifiers in non-destructible glass by LIBS • Manganese is determined as principal component of dark deposits. • Antimony appears in all decorations while lead is only present in yellow ones. • Stratigraphic analysis enables the identification of dealkalinization layers

  18. Laser induced breakdown spectroscopy for analysis and characterization of degradation pathologies of Roman glasses

    Energy Technology Data Exchange (ETDEWEB)

    Palomar, T. [Instituto de Historia, Centro de Ciencias Humanas y Sociales, CSIC, C/Albasanz 26-28, 28037 Madrid (Spain); Oujja, M., E-mail: m.oujja@iqfr.csic.es [Instituto de Química Física Rocasolano, CSIC, C/Serrano 119, 28006 Madrid (Spain); García-Heras, M.; Villegas, M.A. [Instituto de Historia, Centro de Ciencias Humanas y Sociales, CSIC, C/Albasanz 26-28, 28037 Madrid (Spain); Castillejo, M. [Instituto de Química Física Rocasolano, CSIC, C/Serrano 119, 28006 Madrid (Spain)

    2013-09-01

    The feasibility and possibilities of laser induced breakdown spectroscopy (LIBS) in the full study of non-destructible historic glasses have been explored in the present work. Thirteen Roman glass samples, including seven entire glass beads, from the ancient town of Augusta Emerita (SW Spain) were characterized by LIBS in combination with other conventional techniques, such as scanning electron microscopy/energy dispersive X-ray spectrometry, X-ray fluorescence and ultraviolet–visible spectrophotometry. LIBS stratigraphic analysis, carried out by the application of successive laser pulses on the same spot, has been mainly targeted at characterizing particular features of non-destructible historic glasses, such as bulk chemical composition, surface degradation pathologies (dealkalinization layers and deposits), chromophores, and opacifying elements. The obtained data demonstrate that LIBS can be a useful and alternative technique for spectroscopic studies of historical glasses, especially for those conserved under burial conditions and when it deals with studying non-destructible samples. - Highlights: • Determination of chromophores and opacifiers in non-destructible glass by LIBS • Manganese is determined as principal component of dark deposits. • Antimony appears in all decorations while lead is only present in yellow ones. • Stratigraphic analysis enables the identification of dealkalinization layers.

  19. Tunnel restorations using glass ionomer or glass cermet: in vitro marginal ridge fracture and microleakage.

    Science.gov (United States)

    Shetty, R; Munshi, A K

    1996-01-01

    The purpose of this in vitro study was to compare the marginal ridge fracture resistance and microleakage following restorations of partial tunnel preparations using glass ionomer and glass cermet cements. Sixty eight sound premolars were selected for this study and were divided randomly into six groups. A standardized partial tunnel preparation was done on all the teeth except specimens belonging to Group I. The partial tunnel preparations of Groups III & V were restored with glass ionomer and that of Groups IV & VI were restored with glass cermet. The teeth belonging to Groups I, II, III & IV were subjected to marginal ridge fracture resistance testing. The teeth of Groups V & VI were tested for microleakage after immersing them in 5% methylene blue solution for 4 hours. The results indicated that the teeth restored with glass cermet were marginally better than that with glass ionomer in terms of marginal ridge fracture resistance. Both the materials failed to reinforce the marginal ridge to the level of an intact tooth. The microleakage which occurred around both the materials were statistically insignificant, but on comparison glass ionomer showed better results. Hence, glass ionomer is preferred as a restorative material for partial tunnel preparations because of additional inherent advantages like superior esthetics and fluoride leachability.

  20. Fracture Resistance, Surface Defects and Structural Strength of Glass

    NARCIS (Netherlands)

    Rodichev, Y.M.; Veer, F.A.

    2010-01-01

    This paper poses the theory that the fracture resistance of basic float glass is dependent on it physicochemical properties and the surface defects fonned under the float glass production, glass processing and handling at the service conditions compose the aggregate basis for structural glass

  1. Fracturing of simulated high-level waste glass in canisters

    International Nuclear Information System (INIS)

    Peters, R.D.; Slate, S.C.

    1981-09-01

    Waste-glass castings generated from engineering-scale developmental processes at the Pacific Northwest Laboratory are generally found to have significant levels of cracks. The causes and extent of fracturing in full-scale canisters of waste glass as a result of cooling and accidental impact are discussed. Although the effects of cracking on waste-form performance in a repository are not well understood, cracks in waste forms can potentially increase leaching surface area. If cracks are minimized or absent in the waste-glass canisters, the potential for radionuclide release from the canister package can be reduced. Additional work on the effects of cracks on leaching of glass is needed. In addition to investigating the extent of fracturing of glass in waste-glass canisters, methods to reduce cracking by controlling cooling conditions were explored. Overall, the study shows that the extent of glass cracking in full-scale, passively-cooled, continuous melting-produced canisters is strongly dependent on the cooling rate. This observation agrees with results of previously reported Pacific Northwest Laboratory experiments on bench-scale annealed canisters. Thus, the cause of cracking is principally bulk thermal stresses. Fracture damage resulting from shearing at the glass/metal interface also contributes to cracking, more so in stainless steel canisters than in carbon steel canisters. This effect can be reduced or eliminated with a graphite coating applied to the inside of the canister. Thermal fracturing can be controlled by using a fixed amount of insulation for filling and cooling of canisters. In order to maintain production rates, a small amount of additional facility space is needed to accomodate slow-cooling canisters. Alternatively, faster cooling can be achieved using the multi-staged approach. Additional development is needed before this approach can be used on full-scale (60-cm) canisters

  2. Chemical and Oxygen Isotopic Composition of Roman and Late Antique Glass from Northern Greece

    Directory of Open Access Journals (Sweden)

    Alberta Silvestri

    2017-01-01

    Full Text Available The present paper emphasizes the importance of measuring the oxygen isotopic and chemical compositions of ancient glass, in order to constrain some features such as age, raw materials, and production technologies and to identify the “fingerprint” of local productions. In this context, thirty-nine Roman and late Antique glass samples and eight chert samples from northern Greece were selected and analysed for their oxygen isotopic and chemical compositions. Results show that the majority of glass samples are produced using natron as flux and have δ18O values of about 15.5‰, plus or minus a few tenths of one per mil, suggesting that raw materials probably come from Levantine area. Four samples are heavily enriched in 18O, and their chemical composition clearly shows that they were made with soda plant ash as flux. Isotopic and chemical data of Greek chert samples support the hypothesis of local production of the above samples. About half of the glass samples have chemical compositions, which allow their age to be constrained to the late Antique period. For the remaining glass, similarities with literature compositional groups are reported and discussed.

  3. Fracture appraisal of large scale glass block under various realistic thermal conditions

    International Nuclear Information System (INIS)

    Laude, F.; Vernaz, E.; Saint-Gaudens, M.

    1982-06-01

    Fracturing of nuclear waste glass caused primarily by thermal and residual stresses during cooling increases the potential leaching surface area and the number of small particles. A theoretical study shows that it is possible to calculate the stresses created but it is difficult to evaluate the state of fracture. Theoretical results are completed by an experimental study with inactive industrial scale glass blocks. The critical stages of its thermal history are simulated and the total surface area of the pieces is measured by comparison of leaching rate of the fractured glass with known samples in the same conditions. Quenching due to water impact, air cooling in a storage fit and experimental reassembly of fractured glass by re-heating are examined

  4. Scaling exponents for fracture surfaces in opal glass

    Energy Technology Data Exchange (ETDEWEB)

    Chavez-Guerrero, L., E-mail: guerreroleo@hotmail.com [Facultad de Ingenieria Mecanica y Electrica. Cd. Universitaria s/n, C.P. 66450, Universidad Autonoma de Nuevo Leon, Nuevo Leon (Mexico); Center of Innovation, Research and Development on Engineering and Technology, Universidad Autonoma de Nuevo Leon Monterrey, C.P. 66600, Apodaca, Nuevo Leon (Mexico); Garza, F.J., E-mail: fjgarza@gama.fime.uanl.mx [Facultad de Ciencias Quimicas, Cd. Universitaria s/n, C.P. 66450, Universidad Autonoma de Nuevo Leon, Nuevo Leon (Mexico); Hinojosa, M., E-mail: hinojosa@gama.fime.uanl.mx [Facultad de Ingenieria Mecanica y Electrica. Cd. Universitaria s/n, C.P. 66450, Universidad Autonoma de Nuevo Leon, Nuevo Leon (Mexico); Center of Innovation, Research and Development on Engineering and Technology, Universidad Autonoma de Nuevo Leon Monterrey, C.P. 66600, Apodaca, Nuevo Leon (Mexico)

    2010-09-25

    We have investigated the scaling properties of fracture surfaces in opal glass. Specimens with two different opacifying particle sizes (1 {mu}m and 0.4 {mu}m) were broken by three-point bending test and the resulting fracture surfaces were analyzed using Atomic Force Microscopy. The analysis of the self-affine behavior was performed using the Variable Bandwidth and Height-Height Correlation Methods, and both the roughness exponent, {zeta}, and the correlation length, {xi}, were determined. It was found that the roughness exponent obtained in both samples is {zeta} {approx} 0.8; whereas the correlation length in both fractures is of the order of the particle size, demonstrating the dependence of this self-affine parameter on the microstructure of opal glass.

  5. Scaling exponents for fracture surfaces in opal glass

    International Nuclear Information System (INIS)

    Chavez-Guerrero, L.; Garza, F.J.; Hinojosa, M.

    2010-01-01

    We have investigated the scaling properties of fracture surfaces in opal glass. Specimens with two different opacifying particle sizes (1 μm and 0.4 μm) were broken by three-point bending test and the resulting fracture surfaces were analyzed using Atomic Force Microscopy. The analysis of the self-affine behavior was performed using the Variable Bandwidth and Height-Height Correlation Methods, and both the roughness exponent, ζ, and the correlation length, ξ, were determined. It was found that the roughness exponent obtained in both samples is ζ ∼ 0.8; whereas the correlation length in both fractures is of the order of the particle size, demonstrating the dependence of this self-affine parameter on the microstructure of opal glass.

  6. Use of natural and archaeological analogs to validate long - term behaviour of HLW glass in geological disposal conditions

    International Nuclear Information System (INIS)

    Gin, S.; Verney-Carron, A.; Libourel, G.

    2008-01-01

    Some old basaltic and Roman glasses have been studied in order to validate the predictive models developed for assessing the long-term behaviour of nuclear glass in geological repository conditions. Leaching behaviour of basaltic glass altered in both laboratory and natural environment conditions allows to validate the key mechanisms that control glass dissolution kinetics and the order of magnitude of glass packages lifetime In a stable clayey formation (French reference concept for a geological disposal of high level waste). The study of Roman glass blocks (with the same geometry as nuclear glass package) altered during 1800 years in a marine environment gives new insight on the basic mechanisms involved in confined media (fractures and small cracks). Results show the importance of the coupling between transport of reactive species and chemical reactions. This study, still in progress, would allow to validate the modelling of such a complex system. (author)

  7. An electron microscopy appraisal of tensile fracture in metallic glasses

    International Nuclear Information System (INIS)

    Matthews, D.T.A.; Ocelik, V.; Bronsveld, P.M.; De Hosson, J.Th.M.

    2008-01-01

    Three glass-forming alloy compositions were chosen for ribbon production and subsequent electron microscopy studies. In situ tensile testing with transmission electron microscopy (TEM), followed by ex situ TEM and ex situ scanning electron microscopy (SEM), allowed the deformation processes in tensile fracture of metallic glasses to be analysed. In situ shear band propagation was found to be jump-like, with the jump sites correlating with the formation of secondary shear bands. The effect of structural relaxation by in situ heating is also discussed. Nanocrystallization near the fracture surface was observed; however, no crystallization was also reported in the same sample and the reasons for this are discussed. Both the TEM and the SEM observations confirmed the presence of a liquid-like layer on or near the fracture surface of the ribbons. The formation of a liquid-like layer was characterized by the vein geometries and vein densities on the fracture surfaces and its dependence on shear displacement, δ, is discussed. A simple model is adapted to relate the temperature rise during shear banding to the glass transition and melting temperatures and this is used to explain the variety of fracture surfaces which are developed for macroscopically identical tensile testing of metallic glasses together with features which exhibit local melting

  8. Fracture toughness in nuclear waste glasses and ceramics: environmental and radiation effects

    International Nuclear Information System (INIS)

    Weber, W.J.; Matzke, H.J.

    1986-03-01

    The effects of atmospheric moisture and radiation damage on fracture properties of nuclear waste glasses and ceramics was investigated by indentation techniques. In nuclear waste glasses, atmospheric moisture has no measurable effect on hardness but decreases the fracture toughness; radiation damage, on the other hand, decreased the hardness and increased the fracture toughness. In nuclear ceramics, self-radiation damage from alpha decay decreased the hardness and elastic modules; the fracture toughness increased with dose to a broad maximum and then decreased slightly with further increases in dose

  9. The Fracture Process of Tempered Soda-Lime-Silica Glass

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik; Olesen, John Forbes; Stang, Henrik

    2009-01-01

    This work presents experimental observations of the characteristic fracture process of tempered glass. Square specimens with a side length of 300 mm, various thicknesses and a residual stress state characterized by photoelastic measurements were used. Fracture was initiated using a 2.5 mm diamond...

  10. Effect of Chemical Reactions on the Hydrologic Properties of Fractured and Rubbelized Glass Media

    International Nuclear Information System (INIS)

    Saripalli, Prasad; Meyer, P D.; Parker, Kent E.; Lindberg, Michael J.

    2005-01-01

    Understanding the effect of chemical reactions on the hydrologic properties of geological media, such as porosity, permeability and dispersivity, is critical to many natural and engineered sub-surface systems. Influence of glass corrosion (precipitation and dissolution) reactions on fractured and rubbelized (crushed) forms HAN28 and LAWBP1, two candidate waste glass forms for a proposed immobilized low-activity waste (ILAW) disposal facility at the Hanford, WA site, was investigated. Flow and tracer transport experiments were conducted using fractured and rubbelized forms, before and after subjecting them to corrosion using Vapor Hydration Testing (VHT) at 200 C temperature and 200 psig pressure, causing the precipitation of alteration products. Data were analyzed using analytical expressions and CXTFIT, a transport parameter optimization code, for the estimation of the hydrologic characteristics before and after VHT. It was found that glass reactions significantly influence the hydrologic properties of ILAW glass media. Hydrologic properties of rubbelized glass decreased due to precipitation reactions, whereas those of fractured glass media increased due to reaction which led to unconfined expansion of fracture aperture. The results are unique and useful to better understand the effect of chemical reactions on the hydrologic properties of fractured and rubbelized stony media in general and glass media in particular

  11. Fracture behaviour of brittle (glass) matrix composites

    Czech Academy of Sciences Publication Activity Database

    Dlouhý, Ivo; Chlup, Zdeněk; Boccaccini, A. R.

    2005-01-01

    Roč. 482, - (2005), s. 115-122 ISSN 0255-5476. [International Conference on Materials Structure and Micromechanics of Fracture /4./. Brno, 23.06.2004-25.06.2004] R&D Projects: GA AV ČR(CZ) IAA2041003; GA ČR(CZ) GA101/02/0683 Institutional research plan: CEZ:AV0Z2041904 Keywords : Ceramic matrix composites * fracture toughness * toughening effects Subject RIV: JH - Ceramic s, Fire-Resistant Materials and Glass Impact factor: 0.399, year: 2005

  12. Marginal ridge fracture resistance, microleakage and pulpal response to glass ionomer/glass cermet partial tunnel restorations.

    Science.gov (United States)

    Prabhu, N T; Munshi, A K; Shetty, T R

    1997-01-01

    Sixty sound premolars which were to be extracted for orthodontic treatment purposes were restored either with glass ionomer cement or glass cermet cements after partial tunnel preparation, and prior to the extraction after a time interval of 30 and 60 days respectively. The teeth were then subjected to marginal ridge fracture resistance, microleakage study using dye penetration and histological evaluation of the pulpal response to these materials. Both the materials exhibited increase in marginal ridge fracture resistance at 60 days, with minimal degree of microleakage and were biologically compatible with the dental pulp.

  13. Characterization of Roman glass tesserae from the Coriglia excavation site (Italy) via energy-dispersive X-ray fluorescence spectrometry and Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Donais, Mary Kate; Sparks, Andrew; Redente, Monica [Saint Anselm College, Department of Chemistry, Manchester, NH (United States); Pevenage, Jolien van; Moens, Luc; Vincze, Laszlo [Ghent University, Department of Analytical Chemistry, Ghent (Belgium); George, David B. [Saint Anselm College, Department of Classics, Manchester, NH (United States); Vandenabeele, Peter [Ghent University, Department of Archaeology, Ghent (Belgium)

    2016-12-15

    The combined use of handheld energy-dispersive X-ray fluorescence spectrometry, Raman spectroscopy, and micro-energy-dispersive X-ray fluorescence spectrometry permitted the characterization of Roman glass tesserae excavation from the Coriglia (Italy) archeological site. Analyses of ten different glass colors were conducted as spot analyses on intact samples and as both spot analyses and line scans on select cross-sectioned samples. The elemental and molecular information gained from these spectral measurements allowed for the qualitative chemical characterization of the bulk glass, decolorants, opacifiers, and coloring agents. The use of an antimony opacifier in many of the samples supports the late Imperial phasing as determined through numismatic, fresco, ceramics, and architectural evidence. And dealinization of the exterior glass layers caused by the burial environment was confirmed. (orig.)

  14. Understanding the origin of the fracture toughness evolution of nuclear glasses under irradiation

    International Nuclear Information System (INIS)

    Kieu, L.-H.

    2011-01-01

    In the nuclear industry, complex borosilicate glasses are used for the confinement of fission products and long-life minor actinides. Under irradiations, the structure and the mechanical properties of these glasses evolve. In this work, atomistic and multi-scale simulations of three simplified borosilicate glasses were run to understand the origin of their fracture behavior change under irradiation. Under the radiation effects, elasticity decreases and plasticity increases. Fracture happens due to the formation and coalescence of nano-cavities. The structural modifications under the radiation effects lead to a delay of the coalescence and of the irradiated glass rupture. Several phenomena overlay to explain this behavior, especially the cavities distribution modifications, the sodium mobility, and the borate and silicate entities organization in the glassy network. Depending on the nature of the more important mechanism, the fracture toughness can increase or decrease under radiation. (author) [fr

  15. Fractographic features of glass-ceramic and zirconia-based dental restorations fractured during clinical function.

    Science.gov (United States)

    Oilo, Marit; Hardang, Anne D; Ulsund, Amanda H; Gjerdet, Nils R

    2014-06-01

    Fractures during clinical function have been reported as the major concern associated with all-ceramic dental restorations. The aim of this study was to analyze the fracture features of glass-ceramic and zirconia-based restorations fractured during clinical use. Twenty-seven crowns and onlays were supplied by dentists and dental technicians with information about type of cement and time in function, if available. Fourteen lithium disilicate glass-ceramic restorations and 13 zirconia-based restorations were retrieved and analyzed. Fractographic features were examined using optical microscopy to determine crack initiation and crack propagation of the restorations. The material comprised fractured restorations from one canine, 10 incisors, four premolars, and 11 molars. One crown was not categorized because of difficulty in orientation of the fragments. The results revealed that all core and veneer fractures initiated in the cervical margin and usually from the approximal area close to the most coronally placed curvature of the margin. Three cases of occlusal chipping were found. The margin of dental all-ceramic single-tooth restorations was the area of fracture origin. The fracture features were similar for zirconia, glass-ceramic, and alumina single-tooth restorations. Design features seem to be of great importance for fracture initiation. © 2014 Eur J Oral Sci.

  16. Roman glass in the province of Alicante | El vidrio romano en la provincia de Alicante

    Directory of Open Access Journals (Sweden)

    María Dolores Sánchez de Prado

    1984-12-01

    Full Text Available The aim of this study is to spread a sort of material quite ignored by the archaeologycal research: that's the glass, often obtained in the Roman villages and necropolis of Alicante. With regard to its characteristics, we have found two different types: — A top-quality glass, decorated with primitive motives, brought from oriental countries while 1st and 2nd centuries a. C. — A medium-to-low quality glass, decorated with very complicated motives, brought European factories since 3rd century a. C. Quality in raw material was descending as production was getting higher. | Este trabajo pretende fundamentalmente dar a conocer un material muy postergado por la investigación arqueológica: el vidrio, que se ha encontrado con relativa frecuencia en las ciudades y necrópolis de la provincia de Alicante. En el vidrio recogido se pueden distinguir dos grupos: — En las dos primeras centurias de nuestra Era se trata de un vidrio lujoso, de muy buena calidad, liso o decorado con motivos sencillos cuyo carácter es marcadamente oriental. — A partir del siglo III d. C., la calidad de las piezas es menor, aunque las decoraciones más complicadas. Las fábricas occidentales se imponen progresivamente.

  17. Fracture strengths of chair-side-generated veneers cemented with glass fibers.

    Science.gov (United States)

    Turkaslan, S; Bagis, B; Akan, E; Mutluay, M M; Vallittu, P K

    2015-01-01

    CAD/CAM (computer-aided design and computer-aided manufacturing) systems have refreshed the idea of chair-side production of restorations, but the fracture of ceramic veneers remains a problem. Cementation with glass fibers may improve the fracture strengths and affect the failure modes of CAD/CAM-generated ceramic veneers. Therefore, this study compared the fracture strengths of ceramic veneers produced at chair side and cemented with or without glass fibers with those of composite veneers. Thirty intact mandibular incisors were randomly divided into three groups ( n = 10) and treated with CAD/CAM-fabricated veneers cemented with dual-cure composite resin luting cement (CRLC; Group 1), CAD/CAM-fabricated veneers cemented with a glass fiber network (GFN) and dual-cure CRLC (Group 2), and a direct particulate filler composite veneer constructed utilizing fiber and a restorative composite resin (Group 3). The specimens were tested with a universal testing machine after thermal cycling treatment. The loads at the start of fracture were the lowest for traditionally fabricated composite veneers and higher for CAD/CAM-generated. Veneers cemented either without or with the GFN. The failure initiation loads (N) for the veneers were 798.92 for Group 1, 836.27 for Group 2, and 585.93 for Group 3. The predominant failure mode is adhesive failure between the laminates and teeth for Group 1, cohesive failure in the luting layer for Group 2, and cohesive laminate failure for Group 3, which showed chipping and small fractures. Ceramic material is a reliable alternative for veneer construction at chair side. Fibers at the cementation interface may improve the clinical longevity and provide higher fracture strength values.

  18. Dynamic fracture characteristics of Fe78Si9B13 metallic glass subjected to laser shock loading

    International Nuclear Information System (INIS)

    Zheng, Chao; Sun, Sheng; Song, Libin; Zhang, Guofang; Luan, Yiguo; Ji, Zhong; Zhang, Jianhua

    2013-01-01

    The response of the Fe 78 Si 9 B 13 metallic glass under different ratio of laser beam diameter (d) to die hole diameter (D) in micro scale laser punching was investigated. The typical fracture surface morphologies were observed using scanning electron microscope. The influence of the ratio d/D on dynamic deformation and fracture of metallic glasses foils was characterized. The results show that the dynamic fracture behavior of the Fe 78 Si 9 B 13 metallic glass is sensitive to the ratio d/D. In the case of d/D = 1.75, the fracture surface is occupied by numerous liquid droplets, indicating that the temperature rise in an adiabatic shear band is beyond the melting temperature of the material. On the other hand, the fracture surface is covered dominantly with a mixture of shear steps, cellular patterns, liquid droplets and melted belts at d/D = 0.70. According to the general mechanical analysis, the specimen fails in a shear fracture mode at d/D = 1.75 due to the existence of shear stresses, while the fracture occurs in a tensile fracture mode at d/D = 0.70 under the effect of bidirectional tensile stresses.

  19. Measurement of Effect of Chemical Reactions on the Hydrologic Properties of Fractured Glass Media Using a Tri-axial Flow and Transport Apparatus

    International Nuclear Information System (INIS)

    Saripalli, Prasad; Lindberg, Michael J.; Meyer, P. D.

    2006-01-01

    Understanding the effect of chemical reactions on the hydrologic properties of sub-surface media is critical to many natural and engineered sub-surface systems. Methods and information for such characterization of fractured media are severely lacking. Influence of glass corrosion (precipitation and dissolution) reactions on fractured glass blocks HAN28 and LAWBP1, two candidate waste glass forms for a proposed immobilized low-activity waste (ILAW) disposal facility at the Hanford, WA site, was investigated. Flow and tracer transport experiments were conducted in such randomly and multiply fractured ILAW glass blocks, before and after subjecting them to corrosion using Vapor Hydration Testing (VHT) at 200 C temperature and 200 psig (1379 KPa) pressure, causing the precipitation of alteration products. A tri-axial fractured media flow and transport experimental apparatus, which allows the simultaneous measurement of flow and transport properties and their anisotropy, has been designed and built for this purpose. Such apparatus for fractured media characterization are being reported in the literature only recently. Hydraulic properties of fractured blocks were measured in different orientations and along different cardinal directions, before and after glass corrosion reactions. Miscible displacement experiments using a non-reactive dye were also conducted, before and after glass corrosion reactions, to study the tracer transport behavior through such media. Initial efforts to analyze breakthrough curve (BTC) data using a 1D Advection Dispersion Equation (ADE) solution revealed that a different fractured media transport model may be necessary for such interpretation. It was found that glass reactions can have a significant influence on the hydrologic properties of fractured ILAW glass media. The methods and results are unique and useful to better understand the effect of chemical reactions on the hydrologic properties of fractured geomedia in general and glass media in

  20. Flow and Fracture of Bulk Metallic Glass Alloys and their Composites

    International Nuclear Information System (INIS)

    Flores, K M; Suh, D; Howell, R; Asoka-Kumar, P; Dauskardt, R H

    2001-01-01

    The fracture and plastic deformation mechanisms of a Zr-Ti-Ni-Cu-Be bulk metallic glass and a composite utilizing a crystalline reinforcement phase are reviewed. The relationship between stress state, free volume and shear band formation are discussed. Positron annihilation techniques were used to confirm the predicted increase in free volume after plastic straining. Strain localization and failure were examined for a wide range of stress states. Finally, methods for toughening metallic glasses are considered. Significant increases in toughness are demonstrated for a composite bulk metallic glass containing a ductile second phase which stabilizes shear band formation and distributes plastic deformation

  1. Morphological Changes Of The Root Surface And Fracture Resistance After Treatment Of Root Fracture By CO2 Laser And Glass Ionomer Or Mineral Trioxide Aggregates

    Science.gov (United States)

    Badr, Y. A.; Abd El-Gawad, L. M.; Ghaith, M. E.

    2009-09-01

    This in vitro study evaluates the morphological changes of the root surface and fracture resistance after treatment of root cracks by CO2 laser and glass Ionomer or mineral trioxide aggregates (MTA). Fifty freshly extracted human maxillary central incisor teeth with similar dimension were selected. Crowns were sectioned at the cemento-enamel junction, and the lengths of the roots were adjusted to 13 mm. A longitudinal groove with a dimension of 1×5 mm2 and a depth of 1.5 mm was prepared by a high speed fissure bur on the labial surface of the root. The roots were divided into 5 groups: the 10 root grooves in group 1 were remained unfilled and were used as a control group. The 10 root grooves in group 2 were filled with glass Ionomer, 10 root grooves in group 3 were filled with MTA, the 10 root grooves in group 4 were filled with glass Ionomer and irradiated by CO2 laser and the 10 root grooves in group 5 were filled with MTA and irradiated with CO2 laser. Scanning electron microscopy was performed for two samples in each group. Tests for fracture strength were performed using a universal testing machine and a round tip of a diameter of 4 mm. The force was applied vertically with a constant speed of 1 mm min 1. For each root, the force at the time of fracture was recorded in Newtons. Results were evaluated statistically with ANOVA and Turkey's Honestly Significant Difference (HSD) tests. SEM micrographs revealed that the melted masses and the plate-like crystals formed a tight Chemical bond between the cementum and glass Ionomer and melted masses and globular like structure between cementum and MTA. The mean fracture resistance was the maximum fracture resistance in group 5 (810.8 N). Glass Ionomer and MTA with the help of CO2 laser can be an alternative to the treatment of tooth crack or fracture. CO2 laser increase the resistance of the teeth to fracture.

  2. Fracture detection in concrete by glass fiber cloth reinforced plastics

    Science.gov (United States)

    Shin, Soon-Gi; Lee, Sung-Riong

    2006-04-01

    Two types of carbon (carbon fiber and carbon powder) and a glass cloth were used as conductive phases and a reinforcing fiber, respectively, in polymer rods. The carbon powder was used for fabricating electrically conductive carbon powder-glass fiber reinforced plastic (CP-GFRP) rods. The carbon fiber tows and the CP-GFRP rods were adhered to mortar specimens using epoxy resin and glass fiber cloth. On bending, the electrical resistance of the carbon fiber tow attached to the mortar specimen increased greatly after crack generation, and that of the CP-GFRP rod increased after the early stages of deflection in the mortar. Therefore, the CP-GFRP rod is superior to the carbon fiber tow in detecting fractures. Also, by reinforcing with a glass fiber cloth reinforced plastic, the strength of the mortar specimens became more than twice as strong as that of the unreinforced mortar.

  3. Composition, production and procurement of glass at San Vincenzo Al Volturno: an early Medieval monastic complex in Southern Italy.

    Science.gov (United States)

    Schibille, Nadine; Freestone, Ian C

    2013-01-01

    136 glasses from the ninth-century monastery of San Vincenzo and its workshops have been analysed by electron microprobe in order to situate the assemblage within the first millennium CE glass making tradition. The majority of the glass compositions can be paralleled by Roman glass from the first to third centuries, with very few samples consistent with later compositional groups. Colours for trailed decoration on vessels, for vessel bodies and for sheet glass for windows were largely produced by melting the glass tesserae from old Roman mosaics. Some weakly-coloured transparent glass was obtained by re-melting Roman window glass, while some was produced by melting and mixing of tesserae, excluding the strongly coloured cobalt blues. Our data suggest that to feed the needs of the glass workshop, the bulk of the glass was removed as tesserae and windows from a large Roman building. This is consistent with a historical account according to which the granite columns of the monastic church were spolia from a Roman temple in the region. The purported shortage of natron from Egypt does not appear to explain the dependency of San Vincenzo on old Roman glass. Rather, the absence of contemporary primary glass may reflect the downturn in long-distance trade in the later first millennium C.E., and the role of patronage in the "ritual economy" founded upon donations and gift-giving of the time.

  4. Decoding flow unit evolution upon annealing from fracture morphology in metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Gao, M., E-mail: gaomeng10@hotmail.com; Cao, X.F.; Ding, D.W.; Wang, B.B.; Wang, W.H., E-mail: whw@iphy.ac.cn

    2017-02-16

    The intrinsic correlation between the fracture morphology evolution and the structural heterogeneity of flow units in a typical Zr{sub 52.5}Ti{sub 5}Cu{sub 17.9}Ni{sub 14.6}Al{sub 10} (vit105) metallic glass (MG) upon annealing was investigated. By systematically tuning the annealing time at temperature below the glass transition temperature, a series of dimple-like fracture morphology were obtained, which is the unique fingerprint-like pattern for every annealing state. Based on the structural relaxation model of flow units, the evolution of the typical dimple sizes, the largest and smallest dimple size, with annealing were well fitted. Then the evolution of flow unit density was estimated from the fracture morphology evolution, which displays the same evolution trend with that measured from thermal relaxation. A stochastic dynamic model considering the interaction of activated flow units was proposed to analyze the effect of the initial flow unit density and the flow unit interaction intensity on the dynamic evolution of dimple distribution. Our work may provide a novel scheme to investigate the structural fingerprint information on flow units from fracture morphology, and enlighten the microscopic structural origin of the ductile-to-brittle transition during structural relaxation in MGs.

  5. Changes in Fracture Micromechanism with Increasing Reinforcement Volume Fraction in Glass Matrix Composite

    Czech Academy of Sciences Publication Activity Database

    Řehořek, Lukáš; Chlup, Zdeněk; Dlouhý, Ivo; Boccaccini, A. R.

    2008-01-01

    Roč. 567-568, - (2008), s. 369-372 ISSN 0255-5476. [MSMF /5./. Brno, 27.06.2007-29.06.2007] R&D Projects: GA ČR GD106/05/H008; GA ČR GP106/05/P119 Institutional research plan: CEZ:AV0Z20410507 Keywords : glass -ceramics * fracture mechanics * fracture toughness Subject RIV: JL - Materials Fatigue, Friction Mechanics

  6. Discussion on the structural origins of the fracture toughness and hardness changes in rapidly quenched borosilicate glasses: a molecular dynamics study

    International Nuclear Information System (INIS)

    Kieu, L.H.; Kilymis, D.; Delaye, J.M.; Peuget, S.

    2014-01-01

    Understanding radiation effects in nuclear glasses is important in order to assess their long term behaviour in a geological repository. In this paper, the results obtained by classical molecular dynamics about the mechanical properties of a simplified SiO 2 - B 2 O 3 - Na 2 O glass with the same molar proportions as in the real French nuclear glass were reviewed. A pristine and a disordered structure, representative of the irradiated one, were prepared in order to address the question of the radiation effects on the fracture toughness and hardness. In a first step, fracture simulations were performed to compare the atomistic mechanisms in the pristine and disordered glasses. In a second step, nano indentation was simulated using a diamond tip and again the pristine and disordered glass behaviors were compared. The depolymerisation associated to the glass disordering, in particular the increase of the tri-coordinated boron concentration relative to the tetra-coordinated boron concentration improves the fracture resistance by favouring the plastic flows. On the contrary, the swelling of the disordered glass limits the fracture resistance by facilitating the cavity formation. The first effect is dominant in the case of the glass investigated here because, experimentally, the fracture toughness increases after irradiation. Concerning the hardness, both the decrease of the boron coordination in parallel with non-bridging oxygen formation and free volume accumulation lead to a hardness decrease because the more disordered and open structure facilitates the tip penetration. (authors)

  7. Fractography of glass

    CERN Document Server

    Tressler, Richard

    1994-01-01

    As the first major reference on glass fractography, contributors to this volume offer a comprehensive account of the fracture of glass as well as various fracture surface topography Contributors discuss optical fibers, glass containers, and flatglass fractography In addition, papers explore fracture origins; the growth of the original flaws of defects; and macroscopic fracture patterns from which fracture patterns evolve This volume is complete with photographs and schematics

  8. Composition, production and procurement of glass at San Vincenzo Al Volturno: an early Medieval monastic complex in Southern Italy.

    Directory of Open Access Journals (Sweden)

    Nadine Schibille

    Full Text Available 136 glasses from the ninth-century monastery of San Vincenzo and its workshops have been analysed by electron microprobe in order to situate the assemblage within the first millennium CE glass making tradition. The majority of the glass compositions can be paralleled by Roman glass from the first to third centuries, with very few samples consistent with later compositional groups. Colours for trailed decoration on vessels, for vessel bodies and for sheet glass for windows were largely produced by melting the glass tesserae from old Roman mosaics. Some weakly-coloured transparent glass was obtained by re-melting Roman window glass, while some was produced by melting and mixing of tesserae, excluding the strongly coloured cobalt blues. Our data suggest that to feed the needs of the glass workshop, the bulk of the glass was removed as tesserae and windows from a large Roman building. This is consistent with a historical account according to which the granite columns of the monastic church were spolia from a Roman temple in the region. The purported shortage of natron from Egypt does not appear to explain the dependency of San Vincenzo on old Roman glass. Rather, the absence of contemporary primary glass may reflect the downturn in long-distance trade in the later first millennium C.E., and the role of patronage in the "ritual economy" founded upon donations and gift-giving of the time.

  9. Scaling properties of fracture surfaces on glass strengthened by ionic exchange

    International Nuclear Information System (INIS)

    Garza-Mendez, F.J.; Hinojosa-Rivera, M.; Gomez, I.; Sanchez, E.M.

    2007-01-01

    In this work the results of the statistical topometric analysis of fracture surfaces of soda-lime-silica glass with and without ionic exchange treatment are reported. In this case, the mechanism of substitution is K + -Na + . atomic force microscopy (AFM) was employed to record the topometric data from the fracture surface. The roughness exponent (ζ) and the correlation length (ξ) were calculated by the variable bandwidth method. The analysis for both glasses (subjected and non-subjected to ionic exchange) for ζ shows a value ∼0.8, this value agrees well with that reported in the literature for rapid crack propagation in a variety of materials. The correlation length shows different values for each condition. These results, along with those of microhardness indentations suggest that the self-affine correlation length is influenced by the complex interactions of the stress field of microcracks with that resulting from the collective behavior of the point defects introduced by the strengthening mechanism of ionic exchange

  10. Fracture toughness of glass sealants for solid oxide fuel cell application

    DEFF Research Database (Denmark)

    Abdoli, Hamid; Alizadeh, Parvin; Boccaccini, Dino

    2014-01-01

    -opening displacements in the near regions of a crack tip. Both approaches exhibited good agreement. La-containing glass showed higher stiffness, hardness and fracture toughness, which has been related to the in-situ toughening mechanism caused by devitrification and formation of crystalline phases. © 2013 Elsevier B.V....

  11. Fracture toughness of glasses and hydroxyapatite: a comparative study of 7 methods by using Vickers indenter

    OpenAIRE

    HERVAS , Isabel; MONTAGNE , Alex; Van Gorp , Adrien; BENTOUMI , M.; THUAULT , A.; IOST , Alain

    2016-01-01

    International audience; Numerous methods have been proposed to estimate the indentation fracture toughness Kic for brittle materials. These methods generally uses formulæ established from empirical correlations between critical applied force, or average crack length, and classical fracture mechanics tests. This study compares several models of fracture toughness calculation obtained by using Vickers indenters. Two optical glasses (Crown and Flint), one vitroceramic (Zerodur) and one ceramic (...

  12. Fracture toughness study of new Zr-based Be-bearing bulk metallic glasses

    OpenAIRE

    Kim, C. Paul; Suh, Jin-Yoo; Wiest, Aaron; Lind, Mary Laura; Conner, R. Dale; Johnson, William L.

    2009-01-01

    Three new compositional variants of the Zr–Ti–Be–LTM (late transition metal) family of metallic glasses are discussed. Thermal stability, ΔT = T_x−T_g, was increased from 82 °C for Zr_(41.2)Ti_(13.8)Cu_(12.5)Ni_(10)Be_(22.5) (Viterloy 1) to 141 °C for Zr_(44)Ti_(11)Cu_(20)Be_(25). It is found that fracture toughness is the most distinguishing parameter characterizing the alloys in contrast to other mechanical properties. Quaternary alloys consistently had fracture toughness values exceeding 8...

  13. Alpha radiation and in-pile annealing effects on the fracture properties of a sintered alumino borosilicate glass

    International Nuclear Information System (INIS)

    Bevilacqua, Arturo M.; Prado, Miguel O.; Messi de Bernasconi, Norma B.; Heredia, Arturo D.; Sanfilippo, Miguel

    1999-01-01

    The alpha radiation and the in-pile during irradiation effects on the hardness, the crack nucleation and the fracture toughness of the German alumino borosilicate glass SG7 were investigated by using the Vickers indentation. Cold pressed and sintered samples were irradiated with thermal neutrons, in the Argentine nuclear reactors RA-3 and RA-6, to produce alpha particles in the whole volume of the glass by means of the (n, alpha)-reaction with B-10. The Vickers hardness, the crack nucleation, as 50 percent fracture probability load, plotted as the Weibull's fracture probability distribution function and the fracture toughness, as critical stress intensity factor K Ic , were correlated to the four cumulative disintegration values. It was ascertained that: a) the Vickers hardness decreases from 5.6 GPa for the non-irradiated sample up to 4.7 GPa for the sample irradiated 70 h at the lower neutron flux (4.0 x 10 - sup 18 - alpha disintegration per cm - sup 3 -), b) the 50 % fracture probability load increases from 1.4 N for the non-irradiated sample up to 4.7 g for the sample irradiated 22 h at the higher flux (6.8 x 10 - sup 18 - alpha disintegration per cm - sup 3 -), and c) the stress intensity factor increases from 0.80 MPa.m - sup 1/2 - for the non irradiated sample up to 0.86 MPa.m - sup 1/2 - for the sample mentioned in b). The in-pile annealing was analyzed by comparing the crack nucleation after irradiation with data obtained by heavy ion irradiation followed by thermal annealing. Results for the SG7 glass were compared to those for soda-lime and borosilicate glasses. (author)

  14. Analysis of early medieval glass beads - Glass in the transition period

    Energy Technology Data Exchange (ETDEWEB)

    Smit, Ziga, E-mail: ziga.smit@ijs.si [Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana (Slovenia); Jozef Stefan Institute, Jamova 39, P.O.B. 3000, SI-1001 Ljubljana (Slovenia); Knific, Timotej [National Museum of Slovenia, Presernova 20, SI-1000 Ljubljana (Slovenia); Jezersek, David [Jozef Stefan Institute, Jamova 39, P.O.B. 3000, SI-1001 Ljubljana (Slovenia); Istenic, Janka [National Museum of Slovenia, Presernova 20, SI-1000 Ljubljana (Slovenia)

    2012-05-01

    Glass beads from graves excavated in Slovenia and dated archaeologically to the 7th-10th century AD were analysed by the combined PIXE-PIGE method. The results indicate two groups of glass; natron glass made in the Roman tradition and glass made with alkalis from the ash of halophytic plants, which gradually replaced natron glass after c. 800 AD. The alkalis used in the second group of glass seem to be in close relation to a variant of the Venetian white glass that appeared several centuries later. The origin of this glass may be traced to glass production in Mesopotamia and around the Aral Sea. All the mosaic beads with eye decoration, as well as most of the drawn-segmented and drawn-cut beads analysed, are of plant-ash glass, which confirms their supposed oriental origin.

  15. Characterization of a millefiori glass find from Aquincum by SEM-EDX and micro-PIXE methods

    Energy Technology Data Exchange (ETDEWEB)

    Uzonyi, I., E-mail: uzonyi@atomki.hu [Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4026 Debrecen, Bem ter 18/C (Hungary); Csontos, K.; Verebes, A. [Budapest History Museum, Aquincum Museum H-8211 Budapest, Zahony u. 4. (Hungary); Cserhati, C. [Department of Solid State Physics, University of Debrecen H-4032 Debrecen, Bem ter 18/B (Hungary); Csedreki, L.; Kis-Varga, M.; Kiss, A.Z. [Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4026 Debrecen, Bem ter 18/C (Hungary)

    2011-10-15

    Research has been focused on the analysis of archaeological glasses from the Roman age and medieval times. Study of ancient millefiori type glasses from the collection of Hungarian Museums has been started. A test measurement, carried out on a glass fragment supposedly part of a dish, was performed by SEM-EDX and micro-PIXE methods. Complementary analytical data were obtained for texture and composition. Results suggest that Roman and Mesopotamian techniques were used together. Our data contribute to data bases of millefiori glasses.

  16. Characterization of a millefiori glass find from Aquincum by SEM-EDX and micro-PIXE methods

    International Nuclear Information System (INIS)

    Uzonyi, I.; Csontos, K.; Verebes, A.; Cserhati, C.; Csedreki, L.; Kis-Varga, M.; Kiss, A.Z.

    2011-01-01

    Research has been focused on the analysis of archaeological glasses from the Roman age and medieval times. Study of ancient millefiori type glasses from the collection of Hungarian Museums has been started. A test measurement, carried out on a glass fragment supposedly part of a dish, was performed by SEM-EDX and micro-PIXE methods. Complementary analytical data were obtained for texture and composition. Results suggest that Roman and Mesopotamian techniques were used together. Our data contribute to data bases of millefiori glasses.

  17. Rediscovering ancient glass technologies through the examination of opacifier crystals

    Science.gov (United States)

    Lahlil, S.; Biron, I.; Galoisy, L.; Morin, G.

    2008-07-01

    The aim of the study is to understand how antimonate opacifying crystals were obtained throughout history. Two archaeological glass productions opacified with calcium and lead antimonates are studied in this paper, in order to rediscover ancient opaque glass technologies: Roman mosaic tesserae (1st cent. B.C. 4th cent. A.D.) and Nevers lampworking glass (18th cent. A.D.). The fine examination of crystalline phases and of the vitreous matrix is undertaken using various and complementary techniques. Results are compared with a modern reference production, for which the technological process is well known. We demonstrate that Ca-antimonate opacifiers in Roman mosaic tesserae, as well as in Nevers lampworking glass, were obtained by in situ crystallization. Nevertheless, Roman and Nevers glass would have undergone different firing processes. We propose that the addition of previously synthesized crystals or the use of “anime” could be the process used to obtain Pb-antimonate opacified glass, for both productions studied. We demonstrate that CaO, PbO and Sb2O3 concentrations in the bulk compositions and in the matrices, and their evolution with the crystallinity ratio, offer robust criteria for the distinction of the opacification process used. Also, the different crystalline structures help to provide information on the experimental conditions.

  18. The morphologies of fractured surfaces and fracture toughness in some As-Se-Sb-S-I glasses

    International Nuclear Information System (INIS)

    Lukic, S.R.; Petrovic, D.M.; Skuban, F.; Sidanin, L.; Guth, I.O.

    2006-01-01

    As part of a general physical characterization of amorphous materials in the pseudobinary system (As 2 Se 3 ) 100-x (SbSI) x type, their indentation fracture toughness was determined. It is a system with the variable ratio of classical amorphous compound As 2 Se 3 and the molecule of antimony sulfoiodide, SbSI, which in the monocrystal form is characterized as ferroelectrics. Because of chalcogenides are generally very brittle and under load they crack very easily, these glasses have been studied with the aim of examining the possibility of obtaining some new structures on the basis of the materials with amorphous internal network, the structures that will have a higher quality in respect of mechanical properties. The morphologies of fractured surfaces were investigated by scanning electron microscope

  19. The morphologies of fractured surfaces and fracture toughness in some As-Se-Sb-S-I glasses

    Energy Technology Data Exchange (ETDEWEB)

    Lukic, S.R. [Department of Physics, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 4, 21000 Novi Sad (Serbia and Montenegro)]. E-mail: svetdrag@im.ns.ac.yu; Petrovic, D.M. [Department of Physics, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 4, 21000 Novi Sad (Serbia and Montenegro); Skuban, F. [Department of Physics, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 4, 21000 Novi Sad (Serbia and Montenegro); Sidanin, L. [Department for Production Engineering, Faculty of Technical Sciences, University of Novi Sad, Trg D. Obradovica 6, 21000 Novi Sad (Serbia and Montenegro); Guth, I.O. [Department of Physics, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 4, 21000 Novi Sad (Serbia and Montenegro)

    2006-09-15

    As part of a general physical characterization of amorphous materials in the pseudobinary system (As{sub 2}Se{sub 3}){sub 100-x}(SbSI) {sub x} type, their indentation fracture toughness was determined. It is a system with the variable ratio of classical amorphous compound As{sub 2}Se{sub 3} and the molecule of antimony sulfoiodide, SbSI, which in the monocrystal form is characterized as ferroelectrics. Because of chalcogenides are generally very brittle and under load they crack very easily, these glasses have been studied with the aim of examining the possibility of obtaining some new structures on the basis of the materials with amorphous internal network, the structures that will have a higher quality in respect of mechanical properties. The morphologies of fractured surfaces were investigated by scanning electron microscope.

  20. Fracture Energy Estimation of DCB Specimens Made of Glass/Epoxy: An Experimental Study

    Directory of Open Access Journals (Sweden)

    V. Alfred Franklin

    2013-01-01

    Full Text Available This paper examines critical load and corresponding displacement of double cantilever beam (DCB composite specimens made of glass/epoxy of three different layups. Experiments were conducted on these laminates, and the fracture energy, GIc, was evaluated considering the root rotation at the crack tip. The present model requires the applied load-displacement history and crack extension to estimate fracture energy. Reduction schemes based on cubic and power law are also proposed to determine Young’s modulus and energy release rate and found good agreement with the published and test results.

  1. Fracture toughness measurements on a glass bonded sodalite high-level waste form

    International Nuclear Information System (INIS)

    DiSanto, T.; Goff, K. M.; Johnson, S. G.; O'Holleran, T. P.

    1999-01-01

    The electrometallurgical treatment of metallic spent nuclear fuel produces two high-level waste streams; cladding hulls and chloride salt. Argonne National Laboratory is developing a glass bonded sodalite waste form to immobilize the salt waste stream. The waste form consists of 75 Vol.% crystalline sodalite (containing the salt) with 25 Vol.% of an ''intergranular'' glassy phase. Microindentation fracture toughness measurements were performed on representative samples of this material using a Vickers indenter. Palmqvist cracking was confirmed by post-indentation polishing of a test sample. Young's modulus was measured by an acoustic technique. Fracture toughness, microhardness, and Young's modulus values are reported, along with results from scanning electron microscopy studies

  2. Intra-Laminar Fracture Toughness of Glass Fiber Reinforced Polymer By Using Theory, Experimentation and FEA

    Science.gov (United States)

    Firojkhan, Pathan; Tanpure, Kshitijit; Dawale, Ajinkya; Patil, Shital

    2018-04-01

    Fiber reinforced polymer (FRP) composites are widely use in aerospace, marine, auto-mobile and civil engineering applications because of their high strength-to-weight and stiffness-to-weight ratios, corrosion resistance and potentially high durability. The purpose of this research is to experimentally investigate the mechanical and fracture properties of glass-fiber reinforced polyester composite material, 450 g/m 2 randomly distributed glass-fiber mat also known as woven strand mat with polyester resin as a matrix. The samples have been produced by the conventional hand layup process and the specimens were prepared as per the ASTM standards. The tensile test was performed on the composite specimens using Universal testing machine (UTM) which are used for the finite element simulation of composite Layered fracture model. The mechanical properties were evaluated from the stress vs. strain curve obtained from the test result. Later, fracture tests were performed on the CT specimen. In case of CT specimen the load vs. Displacement plot obtained from the experimental results was used to determine the fracture properties of the composite. The failure load of CT specimen using FEA is simulated which gives the Stress intensity factor by using FEA. Good agreement between the FEA and experimental results was observed.

  3. Effect of Ge addition on mechanical properties and fracture behavior of Cu-Zr-Al bulk metallic glass

    International Nuclear Information System (INIS)

    Malekan, M.; Shabestari, S.G.; Gholamipour, R.; Seyedein, S.H.

    2009-01-01

    Effect of the addition of a small amount of Ge on mechanical properties and fracture behavior of Cu 50 Zr 43 Al 7 (at.%) bulk metallic glass were studied. The Cu 50 Zr 43 Al 7 alloy has a surprising glass-forming ability (GFA), and the glassy rods up to 4 mm in diameter can be formed. Partial addition of Ge causes the crystalline phases precipitate in the glassy matrix of (Cu 50 Zr 43 Al 7 ) 100-x Ge x (x = 0, 1, 2) rods with a diameter of 4 mm. In uniaxial compression, Cu 50 Zr 43 Al 7 bulk metallic glass exhibit high strength of 1692 MPa and very limited plasticity of 0.05%. When Ge increases from 0 to 2 at.%, the strength decreases, but plastic strain increases about 2.5%. Fracture surface and shear bands of samples were investigated by scanning electron microscopy (SEM).

  4. Effect of water uptake on the fracture behavior of low-k organosilicate glass

    Science.gov (United States)

    Xiangyu Guo; Joseph E. Jakes; Samer Banna; Yoshio Nishi; J. Leon Shohet

    2014-01-01

    Water uptake in porous low-k dielectrics has become a significant challenge for both back-end-of-the-line integration and circuit reliability. This work examines the effects of water uptake on the fracture behavior of nanoporous low-k organosilicate glass. By using annealing dehydration and humidity conditioning, the roles of different water types...

  5. Fracture frequency and longevity of fractured resin composite, polyacid-modified resin composite, and resin-modified glass ionomer cement class IV restorations: an up to 14 years of follow-up

    DEFF Research Database (Denmark)

    van Dijken, Jan W V; Pallesen, Ulla

    2010-01-01

    The aim of this study was to evaluate the fracture frequency and longevity of fractured class IV resin composite (RC), polyacid-modified resin composite (compomer; PMRC), and resin-modified glass ionomer cement (RMGIC) restorations in a longitudinal long-term follow-up. Eighty-five class IV RC (43...

  6. Determining the fracture resistance of fibre-reinforced glass matrix composites by means of the chevron-notch flexural technique

    Czech Academy of Sciences Publication Activity Database

    Boccaccini, A. R.; Kern, H.; Dlouhý, Ivo

    2001-01-01

    Roč. 308, 1/2 (2001), s. 111-117 ISSN 0921-5093 R&D Projects: GA ČR GV101/96/K264 Institutional research plan: CEZ:AV0Z2041904 Keywords : glass matrix composites * fracture toughness * chevron notch test Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.978, year: 2001

  7. Effect of adhesive luting on the fracture resistance of zirconia compared to that of composite resin and lithium disilicate glass ceramic

    Directory of Open Access Journals (Sweden)

    Myung-Jin Lim

    2017-02-01

    Full Text Available Objectives The purpose of this study was to evaluate the effect of adhesive luting on the fracture resistance of zirconia compared to that of a composite resin and a lithium disilicate glass ceramic. Materials and Methods The specimens (dimension: 2 mm × 2 mm × 25 mm of the composite resin, lithium disilicate glass ceramic, and yttria-stabilized tetragonal zirconia polycrystal (Y-TZP were prepared. These were then divided into nine groups: three non-luting groups, three non-adhesive luting groups, and three adhesive luting groups, for each restorative material. In the non-luting groups, specimens were placed on the bovine tooth without any luting agents. In the non-adhesive luting groups, only zinc phosphate cement was used for luting the specimen to the bovine tooth. In the adhesive luting groups, specimens were pretreated, and the adhesive luting procedure was performed using a self-adhesive resin cement. For all the groups, a flexural test was performed using universal testing machine, in which the fracture resistance was measured by recording the force at which the specimen was fractured. Results The fracture resistance after adhesive luting increased by approximately 29% in the case of the composite resin, 26% in the case of the lithium disilicate glass ceramic, and only 2% in the case of Y-TZP as compared to non-adhesive luting. Conclusions The fracture resistance of Y-TZP did not increased significantly after adhesive luting as compared to that of the composite resin and the lithium disilicate glass ceramic.

  8. Effect of static pre-loading on fracture toughness of Nicalon fibre glass matrix composite

    Czech Academy of Sciences Publication Activity Database

    Dlouhý, Ivo; Chlup, Zdeněk; Chawla, K. K.; Kulkarmi, R.; Koopman, M.; Boccaccini, A. R.

    č. 367 (2004), s. 17-23 ISSN 0921-5093 R&D Projects: GA AV ČR IAA2041003; GA MŠk ME 491 Institutional research plan: CEZ:AV0Z2041904 Keywords : Nicalon fibre * glass matrix composite * fracture toughness Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.445, year: 2004

  9. Fracture resistance of dental nickel–titanium rotary instruments with novel surface treatment: Thin film metallic glass coating

    Directory of Open Access Journals (Sweden)

    Chih-Wen Chi

    2017-05-01

    Conclusion: The novel surface treatment of Ti-Zr-B thin film metallic glass on dental NiTi rotary files can effectively improve the fatigue fracture resistance by offering a smooth coated surface with amorphous microstructure.

  10. The Roman-Irish Bath: Medical/health history as therapeutic assemblage.

    Science.gov (United States)

    Foley, Ronan

    2014-04-01

    The invention of a new form of hot-air bath in Blarney, Ireland in 1856, variously known in its lifetime as the Roman-Irish or Turkish Bath, acted as the starting point for a the production of a globalised therapeutic landscape. Tracking the diffusion of the Roman-Irish bath template from its local invention in Ireland to a global reach across the Victorian world and recognizing its place within a wider hydrotherapeutic history, this paper frames that diffusion as a valuable empirical addition to assemblage theory. The specific empirical history of the spread of the Roman-Irish/Turkish bath idea is drawn from primary archival and secondary historical sources. It is then discussed and, drawing from work on assemblage theory, analyzed against three broad themes: mobile networks, socio-material practices and contested emergence. The emergent relational geographies of the Roman-Irish Bath identify important roles for the diffusion and transformation of specific medical settings, identities and functions. These were linked in turn to competing social-healing pathways wherein bodies were technologically and morally managed, to produce a more inhabited form of therapeutic assemblage. In all cases the differential diffusion of the bath idea, it's shifting and fractured material forms and multiple inhabitations and discourses were contested and mobile and spoke to an assemblage approach which has ripe potential for exploration across a range of medical/health geography settings. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. PECVD low-permittivity organosilicate glass coatings: Adhesion, fracture and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Lin Youbo; Xiang Yong [School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138 (United States); Tsui, Ting Y. [Department of Chemical Engineering, Nanotechnology Institute, University of Waterloo, 200 University Avenue West, Waterloo, Ont., N2L 3G1 (Canada); Vlassak, Joost J. [School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138 (United States)], E-mail: vlassak@esag.harvard.edu

    2008-10-15

    The structure and mechanical behavior of organosilicate glass (OSG) coatings have been analyzed as a function of composition and UV irradiation time. A decrease in the OSG carbon content results in more networking bonds and increased connectivity; UV irradiation increases the connectivity by severing weak terminal bonds and stabilizes the network through local bond rearrangements. These structure modifications lead to a significant improvement in the stiffness, hardness, and fracture energy of these coatings. The networking bond density and mean connectivity number correlate well with the mechanical behavior of the OSG films, although network bond density weighted by bond energy is a more appropriate measure. The adhesion energy of silicon nitride to OSG is significantly higher than the cohesive energy of the OSG as a result of interface densification and crack-tip shielding. Subcritical fracture measurements in aqueous environments show that the detrimental effect of water on adhesion surpasses the effect of network connectivity.

  12. Fracture and subcritical crack-growth behavior of Y-Si-Al-O-N glasses and Si3N4 ceramics

    International Nuclear Information System (INIS)

    Bhatnagar, A.; Hoffman, M.J.; Dauskardt, R.H.

    2000-01-01

    Fracture and environmentally assisted subcritical crack-growth processes are examined in bulk Y-Si-Al-O-N oxynitride glasses with compositions typical of the grain boundary phase of silicon nitride ceramics. Both long-crack (in compact tension specimens) as well as short-crack behavior (using indentation techniques) were investigated to establish a reliable fracture toughness and to elucidate the anomalous densification behavior of the oxynitride glass. Environmentally assisted subcritical crack-growth processes were studied in inert, moist, and wet environments under both cyclic and static loading conditions. Behavior is discussed in terms of the interaction of the environment with the crack tip. Likely mechanisms for environmentally assisted crack growth are discussed and related to the subcritical crack-growth behavior of silicon nitride ceramics

  13. Resistance to fracture of endodontically treated premolars restored with glass ionomer cement or acid etch composite resin: An in vitro study

    Directory of Open Access Journals (Sweden)

    B Ranga

    2010-01-01

    Full Text Available Aim: Due to the weakness of endodontically treated posterior teeth requires more strengthened restoration to withstand occlusal forces. The purpose of the present study was to determine and compare the resistance to fracture of endodontically treated maxillary 1 st premolars restored with different materials in mesio-occluso-distal (MOD cavity preparations. Materials and Methods: MOD cavity preparations in 80 endodontically treated maxillary 1 st premolars were restored using four different methods. Fiber rings were filled with stone plaster and the teeth were placed into the plaster up to the level of cemento-enamel junction. The teeth were grouped according to restorative method, mounted in an Instrom T.T. machine, and the buccal walls subjected to a slowly increasing compressive force until fracture occurred. Result: The force of fracture of the walls of each tooth was recorded and the results in the various groups compared. All teeth fractured in a similar manner irrespective of the restorative method used. Conclusion: The resistance to the fracture of the teeth was the same when they were stored with glass ionomer cement as a base over which composite resin was placed. When the entire cavities were filled with glass ionomer cement, the resistance to fracture of the teeth decreased significantly compared with the acid etch resin technique.

  14. Beyond Romanization: The creolization of food. A framework for the study of faunal remains from Roman sites.

    Directory of Open Access Journals (Sweden)

    Gillian Hawkes

    1999-11-01

    Full Text Available The effects of the Roman conquest of Britain and the ensuing processes of Romanization have been studied for many years. The historical background to the development of the theory of Romanization has been widely discussed elsewhere (see Hingley 1996. Haverfield’s (1906 treatment of the topic was a major landmark in this development. He considered that the Roman conquest was a ‘good’ thing as it brought civilisation to the ‘natives’ who, recognising the superiority of Roman culture, willingly embraced `Roman-ness`. The theory of Romanization was further refined by Millett (1990 in The Romanization of Britain. The assumption that underlies Millett’s model is that cultural artefacts which to archaeologists look ‘Roman’ were perceived in the same way in the past. But need this be so? This paper will concern itself with looking at new approaches to culture change, especially relating to food, following the Roman conquest in Britain. It will aim to suggest methods of applying these new approaches to faunal remains, which will enable us to evolve a more subtle understanding of food in the Roman period.

  15. Fracture resistance of dental nickel-titanium rotary instruments with novel surface treatment: Thin film metallic glass coating.

    Science.gov (United States)

    Chi, Chih-Wen; Deng, Yu-Lun; Lee, Jyh-Wei; Lin, Chun-Pin

    2017-05-01

    Dental nickel-titanium (NiTi) rotary instruments are widely used in endodontic therapy because they are efficient with a higher success rate. However, an unpredictable fracture of instruments may happen due to the surface characteristics of imperfection (or irregularity). This study assessed whether a novel surface treatment could increase fatigue fracture resistance of dental NiTi rotary instruments. A 200- or 500-nm thick Ti-zirconium-boron (Ti-Zr-B) thin film metallic glass was deposited on ProTaper Universal F2 files using a physical vapor deposition process. The characteristics of coating were analyzed by scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. In cyclic fatigue tests, the files were performed in a simulated root canal (radius=5 mm, angulation=60°) under a rotating speed of 300rpm. The fatigue fractured cross sections of the files were analyzed with their fractographic performances through scanning electron microscopy images. The amorphous structure of the Ti-Zr-B coating was confirmed by transmission electron microscopy and X-ray diffractometry. The surface of treated files presented smooth morphologies without grinding irregularity. For the 200- and 500-nm surface treatment groups, the coated files exhibited higher resistance of cyclic fatigue than untreated files. In fractographic analysis, treated files showed significantly larger crack-initiation zone; however, no significant differences in the areas of fatigue propagation and catastrophic fracture were found compared to untreated files. The novel surface treatment of Ti-Zr-B thin film metallic glass on dental NiTi rotary files can effectively improve the fatigue fracture resistance by offering a smooth coated surface with amorphous microstructure. Copyright © 2016. Published by Elsevier B.V.

  16. Measuring Mechanical Properties Of Optical Glasses

    Science.gov (United States)

    Tucker, Dennis S.; Nichols, Ronald L.

    1989-01-01

    Report discusses mechanical tests measuring parameters of strength and fracture mechanics of optical glasses. To obtain required tables of mechanical properties of each glass of interest, both initial-strength and delayed-fracture techniques used. Modulus of rupture measured by well-known four-point bending method. Initial bending strength measured by lesser-known double-ring method, in which disk of glass supported on one face near edge by larger ring and pressed on its other face by smaller concentric ring. Method maximizes stress near center, making it more likely specimen fractures there, and thereby suppresses edge effects. Data from tests used to predict reliabilities and lifetimes of glass optical components of several proposed spaceborne instruments.

  17. On The Roman Domination Stable Graphs

    Directory of Open Access Journals (Sweden)

    Hajian Majid

    2017-11-01

    Full Text Available A Roman dominating function (or just RDF on a graph G = (V,E is a function f : V → {0, 1, 2} satisfying the condition that every vertex u for which f(u = 0 is adjacent to at least one vertex v for which f(v = 2. The weight of an RDF f is the value f(V (G = Pu2V (G f(u. The Roman domination number of a graph G, denoted by R(G, is the minimum weight of a Roman dominating function on G. A graph G is Roman domination stable if the Roman domination number of G remains unchanged under removal of any vertex. In this paper we present upper bounds for the Roman domination number in the class of Roman domination stable graphs, improving bounds posed in [V. Samodivkin, Roman domination in graphs: the class RUV R, Discrete Math. Algorithms Appl. 8 (2016 1650049].

  18. Investigations of Archaeological Glass Bracelets and Perfume Bottles Excavated in Ancient Ainos (Enez) by Multiple Analytical Techniques

    Science.gov (United States)

    Celik, S.; Akyuz, T.; Akyuz, S.; Ozel, A. E.; Kecel-Gunduz, S.; Basaran, S.

    2018-03-01

    Fragments of two perfume bottles belonging to the Hellenistic and Roman periods, and five bracelets belonging to the Roman, Byzantine, and Ottoman periods, excavated in the archaeological site of Enez during the excavations in 2000, have been investigated. The samples were analyzed using micro-Raman, FTIR, and energy dispersive X-ray fluorescence techniques, in order to study the ancient technology of glass production and to determine chemical compositions of the basic components and coloring elements of the glassware. All the investigated glasses can be characterized as low-magnesia-soda-lime silicate glasses, whose colors are induced by metal ions. The melting points of the investigated glasses are estimated to be quite close to each other and around 1000°C.

  19. Greco-Roman Stone Disease

    Science.gov (United States)

    Moran, Michael E.; Ruzhansky, Katherine

    2008-09-01

    Greek and Roman thought had a profound influence upon Western medical practice. From the fall of the Greek civilization to the fall of the Roman, remarkable progress of our understanding of human anatomy and physiology occurred. Here we review the attempts of Greek and Roman thinkers to develop the first understanding of the pathophysiology of urolithiasis, its epidemiology, differential diagnosis of renal versus bladder stones, medications for both colic and prevention, the role of familial syndromes, and dietary management.

  20. "Roman Baths" in Contemporary Spa Tourism

    Directory of Open Access Journals (Sweden)

    Vesna Merc

    2005-07-01

    Full Text Available The commercialisation of images and symbols from antiquity, so characteristic of Slovenia since its independence, has been reflected over the last decade in spa tourism as well. Since the great crises in the sixties, and especially since the eighties, fifteen Slovene natural health resorts have concentrated on developing wellness and activities programs. This change in orientation has been accompanied by renovations, an expansion of the water surfaces and capacities, and new wellbeing, wellness, spirituality and beauty programs. An analysis of Slovene spas, wellness centres and hotel web pages shows that they frequently offer rooms, usually saunas, which are imitations of the Roman baths. These rooms are usually called "Roman saunas", "Tepidarium", "Caldarium", and "Roman-Irish baths". At Terme Ptuj, Zdravilišče Laško, Šmarješke Toplice, Grand Hotel Palace in Portorož, and Terme Čatež, saunas have been built or renovated in the Roman style. This trend of Roman rooms is a novelty, less than a decade old in Slovenia. The first sauna with a Roman theme, a Roman-Irish bath, was opened in 1997 in the Health and Beauty Centre at Terme Čatež. Modern Roman saunas are very popular, found not only in Slovenia but also in other parts of Europe, especially Germany and Austria. Their popularity has spread from the areas formerly occupied by the Romans to other parts of world, for example the USA and the Republic of South Africa. An analysis of Slovene saunas and wellness centres reveals a well-established trend to recreate certain parts of the Roman baths. This is attempted not only through Roman-style decorations, but also through certain structures particular to the Roman baths, such as the caldarium, tepidarium, and in one case even a laconicum. The approach, however, is highly eclectic, blending Roman, Greek and, above all, modern elements. The purpose of such rooms is to increase the appeal of the spas, while their design is mostly based on

  1. Creep fracture and creep-fatigue fracture in ceramics and ceramic composites

    International Nuclear Information System (INIS)

    Suresh, S.

    1993-01-01

    This paper summarizes recent advances in the areas of subcritical crack growth in ceramics subjected to static and cyclic loads at elevated temperatures. Attention is devoted to the specific role of pre-existing and in-situ-formed glass films in influencing creep fracture and creep-fatigue fracture. Experimental results on the effects of cyclic frequency and load ratio, along with detailed transmission electron microscopy of crack-tip and crack-wake damage are highlighted. Some general conclusions are drawn about the dependence of high-temperature damage tolerance on interfacial glass films and about the susceptibility of ceramic materials to cyclic fatigue fracture

  2. Degradation of glass in the soil

    Energy Technology Data Exchange (ETDEWEB)

    Romich, H.; Gerlach, S.; Mottner, P. [Fraunhofer-Institut fur Silicatforschung (ISC), Wertheim-Bronnbach (Germany)

    2004-07-01

    Full text of publication follows: Glass has been produced and used in Europe for over 2000 years. Glass objects from the Roman period onwards have been excavated during the last centuries. In general, Roman glass is chemically quite stable, and often the only sign of chemical alteration is an iridescent surface, caused by the leaching of cations, which leads to the formation of a hydrated silica-rich layer. Medieval potash glasses are much less durable, and their surfaces are often found deeply leached, sometimes to a point that no unaltered glass remains. These surfaces may be coherent, though fragile, or they are laminar, with no cohesion between the layers at all. In this study an analytical examination of a series of fragments of archaeological glass retrieved from different sites near Cologne and Stuttgart (Germany) has been carried out. Samples of corroded glasses were analysed by optical microscopy and SEM/EDX (surface and cross sections) in order to obtain information about the chemical composition of the bulk glass and the weathered layers. Since the environmental parameters have constantly varied for archaeological objects, mechanistic studies have to rely on laboratory experiments under controlled conditions. For an extensive exposure programme standardised soil or natural garden earth was used, for which the pH was modified. Several corrosion sensitive potash-lime silicate glasses have been designed to study the effect of glass composition. A model glass consisting of SiO{sub 2} (54.2), CaO (28.8) and K{sub 2}O (17.0 weight-%) mostly lead to the formation of a crust on the leached layer, with a total thickness of 100 micrometer (for soil with pH 7 to 8, 12 months exposure). Model glasses also containing Al, Mg and P have built up preferably laminated structures (total thickness up to 200 micrometer). This presentation will give an overview about the variety of degradation phenomena observed on originals and compare the results with controlled laboratory

  3. Vidrios romanos de Bracara Augusta (Portugal: Análisis Arqueométrico = Roman glass from Bracara Augusta (Portugal: Archaeometric analysys

    Directory of Open Access Journals (Sweden)

    Rosario García Giménez

    2015-11-01

    Full Text Available En este trabajo se han estudiado vidrios romanos de Bracara Augusta, actualmente Braga (Portugal, a través de su composición química, analizando los constituyentes mayoritarios, minoritarios y traza mediante espectrometría de plasma-masas (ICPMS. Los resultados obtenidos han sido tratados estadísticamente, por un lado realizando diversos análisis univariantes, y por otro llevando a cabo una clasificación de las muestras mediante análisis de clasificación jerárquica y varios análisis discriminantes. Se llega a la conclusión de que, si bien todas las muestras de vidrio presentan una composición parecida en cuanto a los elementos mayoritarios, existen algunas diferencias significativas tanto en éstos como en los elementos minoritarios estudiados que permiten su clasificación. Además, mediante el análisis discriminante se establecen grupos en función de la datación de los vidrios y se pueden incluir en ellos las muestras previamente no datadas en los grupos anteriores.In this work Roman glass from Bracara Augusta, nowadays Braga (Portugal, were studied through their chemical composition, analyzing the major, minor and trace constituents using plasma-mass spectrometry (ICP-MS. The obtained data were statistically analysed, with the following statistical methodologies: (i various  univariate analyses and (ii several multivariate analyses which gave rise to a sample classification using hierarchical classification and by multiple discriminant analyses. Results concluded that, while all the glass samples showed a similar composition in terms of major components, there were some significant differences in these and in the minor components that allowed their classification. Furthermore, discriminant analysis helped to establish groups based on the dating of the glass and include undated samples in the previous stated groups.

  4. Den moderne tyske roman 1909-35

    DEFF Research Database (Denmark)

    Ved siden af klassikken og romantikken er den tidlige modernisme vel nok den betydeligste periode i tysksproget litteratur. Det skyldes ikke mindst den perlerække af romaner, der udkom i første tredjedel af det 20. århundrede, og hvoraf mange i dag fremstår som indiskutable højdepunkter i såvel...... tysk som europæisk roman- og litteraturhistorie. I Den moderne tyske roman 1909-35 behandles en række af disse romaner for første gang samlet på dansk. Bogen består af otte romanfortolkninger samt en indledende artikel om den moderne romans historie og særpræg. Alle artikler er skrevet med et solidt...... interesserede læser. I overensstemmelse med dens formidlende sigte er der kun medtaget fortolkninger af romaner, der foreligger på dansk i en tidssvarende oversættelse. Af hensyn til den litteraturhistoriske bredde er der desuden kun medtaget én roman af samme forfatter.Bogen indeholder analyser af: Robert...

  5. Archeological glass from the Ciutadella de Roses site (Empordà, Girona, NE Spain): chemical characterization

    Science.gov (United States)

    Garcia-Valles, M.; Puig, A. M.; Gimeno, D.; Aulinas, M.

    2012-04-01

    The town of Roses is placed in the homonymous bay some 15 km north of the greek-roman city of Emporium, in the Empordà Country (Catalonia, NE Spain). The north sector of the Empordà constitutes a fertile river plain located within the Pyrenees Range and the Montgrí calcareous block that has been extensively occupied at least since Neolitic times. The Roses fortress is a space of more than 130.000 m2 of renaissance style built in 1543 that constitutes one of the rare fort places preserved in Catalonia after the Succession War (1701-1714). The archaeological excavations conducted in the area of the Ciutadella have shown the rests of the Greek city of Rhode, founded at 776 B.C. by Rhodian people; the Hellenistic quartier (especially important at IV-III centuries B.C.; a roman villa (occupied between centuries II B.C. and VI D.C.); a romain-lombard monastery (Santa Maria, century XI), and a series of rests till century XIX. The excavations conducted in the period 1993-1996 provided glass remnants of several ages in a number of strata at several places within the Ciutadella walls. A number of 25 samples were chosen and cleaned in order to characterize its main chemistry by EMPA. Samples were mounted on a epoxy resin, cut and polished, and external sectors with surface alteration were avoided during analysis. The major constituents Si, Al, Na, K, Fe, Mn, Ca, Mg, Ti and P were analysed, as well as a number of trace elements (metals) that give indication on the colour of glass: Co, Cu, Cr, Sb and Pb. The archaeological data allow dating the concerned strata in several periods: end of VI century-beginning of VII (3 samples) and from middle XVI century to XVIII century. The scope of this work is to provide a first characterization of the glass chemical composition variation along time since late roman times in a near to permanent occupied site. All the studied glass fragments show a sodic-lime composition, being the ones corresponding to VI-VII of low magnesia and

  6. The understanding of the R7T7 glass blocks long term behavior: chemical and transport coupling in fractured media

    International Nuclear Information System (INIS)

    Chomat, L.

    2008-04-01

    The long term behavior of nuclear waste glass blocks depends highly on chemical reactions which occur at the surface in contact with water. Studies carried out on inactive fractured glass blocks show that fracture networks play a significant part in reactive surface area. Nevertheless, the complexity of results interpretation, due to a weak knowledge of fracture networks and local lixiviation conditions, does not allow us to comprehend the physical and chemical mechanisms involved. Model cracks are a key step to study chemical and transport coupling in fractured media. Crack lixiviation in aggressive conditions (pH≥11) show that the crack's position (horizontal or vertical) determines the dominant transport mechanism (respectively diffusion or convection induced by gravity). This gravity driven flow seems to be negligible in lower pH conditions. The convective velocity is estimated by a 1D model of reactive transport. Two other parameters are studied: the influence of thermal gradient and the influence of interconnected cracks on alteration. A strong retroactive effect of convection, due to thermal gradient, on the alteration kinetic is observed inside the crack. These works lead to a complete alteration experiment of a 163 crack network subject to a thermal gradient. The use of the geochemical software, HYTEC, within the framework of this study shows the potential of the software which is however limited by the kinetics law used. (author)

  7. Low Velocity Sphere Impact of a Borosilicate Glass

    Energy Technology Data Exchange (ETDEWEB)

    Morrissey, Timothy G [ORNL; Ferber, Mattison K [ORNL; Wereszczak, Andrew A [ORNL; Fox, Ethan E [ORNL

    2012-05-01

    This report summarizes US Army TARDEC sponsored work at Oak Ridge National Laboratory (ORNL) involving low velocity (< 30 m/s or < 65 mph) ball impact testing of Borofloat borosilicate glass, and is a follow-up to a similar study completed by the authors on Starphire soda-lime silicate glass last year. The response of the borosilicate glass to impact testing at different angles was also studied. The Borofloat glass was supplied by the US Army Research Laboratory and its tin-side was impacted or indented. The intent was to better understand low velocity impact response in the Borofloat. Seven sphere materials were used whose densities bracket that of rock: borosilicate glass, soda-lime silicate glass, silicon nitride, aluminum oxide, zirconium oxide, carbon steel, and a chrome steel. A gas gun or a ball-drop test setup was used to produce controlled velocity delivery of the spheres against the glass tile targets. Minimum impact velocities to initiate fracture in the Borofloat were measured and interpreted in context to the kinetic energy of impact and the elastic property mismatch between the seven sphere-Borofloat-target combinations. The primary observations from this low velocity (< 30 m/s or < 65 mph) testing were: (1) BS glass responded similarly to soda-lime silicate glass when spherically indented but quite differently under sphere impact conditions; (2) Frictional effects contributed to fracture initiation in BS glass when it spherically indented. This effect was also observed with soda-lime silicate glass; (3) The force necessary to initiate fracture in BS glass under spherical impact decreases with increasing elastic modulus of the sphere material. This trend is opposite to what was observed with soda-lime silicate glass. Friction cannot explain this trend and the authors do not have a legitimate explanation for it yet; (4) The force necessary to initiate contact-induced fracture is higher under dynamic conditions than under quasi-static conditions. That

  8. Time-dependent fracture probability of bilayer, lithium-disilicate-based glass-ceramic molar crowns as a function of core/veneer thickness ratio and load orientation

    Science.gov (United States)

    Anusavice, Kenneth J.; Jadaan, Osama M.; Esquivel–Upshaw, Josephine

    2013-01-01

    Recent reports on bilayer ceramic crown prostheses suggest that fractures of the veneering ceramic represent the most common reason for prosthesis failure. Objective The aims of this study were to test the hypotheses that: (1) an increase in core ceramic/veneer ceramic thickness ratio for a crown thickness of 1.6 mm reduces the time-dependent fracture probability (Pf) of bilayer crowns with a lithium-disilicate-based glass-ceramic core, and (2) oblique loading, within the central fossa, increases Pf for 1.6-mm-thick crowns compared with vertical loading. Materials and methods Time-dependent fracture probabilities were calculated for 1.6-mm-thick, veneered lithium-disilicate-based glass-ceramic molar crowns as a function of core/veneer thickness ratio and load orientation in the central fossa area. Time-dependent fracture probability analyses were computed by CARES/Life software and finite element analysis, using dynamic fatigue strength data for monolithic discs of a lithium-disilicate glass-ceramic core (Empress 2), and ceramic veneer (Empress 2 Veneer Ceramic). Results Predicted fracture probabilities (Pf) for centrally-loaded 1,6-mm-thick bilayer crowns over periods of 1, 5, and 10 years are 1.2%, 2.7%, and 3.5%, respectively, for a core/veneer thickness ratio of 1.0 (0.8 mm/0.8 mm), and 2.5%, 5.1%, and 7.0%, respectively, for a core/veneer thickness ratio of 0.33 (0.4 mm/1.2 mm). Conclusion CARES/Life results support the proposed crown design and load orientation hypotheses. Significance The application of dynamic fatigue data, finite element stress analysis, and CARES/Life analysis represent an optimal approach to optimize fixed dental prosthesis designs produced from dental ceramics and to predict time-dependent fracture probabilities of ceramic-based fixed dental prostheses that can minimize the risk for clinical failures. PMID:24060349

  9. Time-dependent fracture probability of bilayer, lithium-disilicate-based, glass-ceramic, molar crowns as a function of core/veneer thickness ratio and load orientation.

    Science.gov (United States)

    Anusavice, Kenneth J; Jadaan, Osama M; Esquivel-Upshaw, Josephine F

    2013-11-01

    Recent reports on bilayer ceramic crown prostheses suggest that fractures of the veneering ceramic represent the most common reason for prosthesis failure. The aims of this study were to test the hypotheses that: (1) an increase in core ceramic/veneer ceramic thickness ratio for a crown thickness of 1.6mm reduces the time-dependent fracture probability (Pf) of bilayer crowns with a lithium-disilicate-based glass-ceramic core, and (2) oblique loading, within the central fossa, increases Pf for 1.6-mm-thick crowns compared with vertical loading. Time-dependent fracture probabilities were calculated for 1.6-mm-thick, veneered lithium-disilicate-based glass-ceramic molar crowns as a function of core/veneer thickness ratio and load orientation in the central fossa area. Time-dependent fracture probability analyses were computed by CARES/Life software and finite element analysis, using dynamic fatigue strength data for monolithic discs of a lithium-disilicate glass-ceramic core (Empress 2), and ceramic veneer (Empress 2 Veneer Ceramic). Predicted fracture probabilities (Pf) for centrally loaded 1.6-mm-thick bilayer crowns over periods of 1, 5, and 10 years are 1.2%, 2.7%, and 3.5%, respectively, for a core/veneer thickness ratio of 1.0 (0.8mm/0.8mm), and 2.5%, 5.1%, and 7.0%, respectively, for a core/veneer thickness ratio of 0.33 (0.4mm/1.2mm). CARES/Life results support the proposed crown design and load orientation hypotheses. The application of dynamic fatigue data, finite element stress analysis, and CARES/Life analysis represent an optimal approach to optimize fixed dental prosthesis designs produced from dental ceramics and to predict time-dependent fracture probabilities of ceramic-based fixed dental prostheses that can minimize the risk for clinical failures. Copyright © 2013 Academy of Dental Materials. All rights reserved.

  10. Fracture-free surfaces of CAD/CAM lithium metasilicate glass-ceramic using micro-slurry jet erosion.

    Science.gov (United States)

    Yin, Ling; Baba, Takashi; Nakanishi, Yoshitaka

    2018-04-01

    This paper reports the use of micro-slurry jet erosion (MSJE) on CAD/CAM lithium mesilicate glass ceramic (LMGC) that is capable of achieving the fracture-free surface quality. A computer-controlled MSJE process using a low-pressure and low-concentration alumina slurry was applied to diamond-ground LMGC surfaces with surface and subsurface damage. The MSJE processed and diamond-ground LMGC surfaces were examined using scanning electron microscopy (SEM) to examine surface morphology, fractures, and residual defects. 3D confocal laser microscopy (CLM) was used to quantitatively characterize all machined surface textures as a function of processing conditions. Our results show that surface and subsurface damage induced in diamond-ground surfaces were significantly diminished after 50-cycle MSJE processing. Fracture-free surfaces were obtained after 100 MSJE cycles. Our measured parameters of the 3D surface topography included the average surface roughness, maximum peak-valley height, highest peak height, lowest valley height, and kurtosis and absolute skewness of height distributions. All these parameters were significantly reduced with the increase of MSJE cycles. This work implies that MSJE promises to be an effective manufacturing technique for the generation of fracture-free LMGC surfaces which are crucial for high-quality monolithic restorations made from the material. Copyright © 2018 Elsevier Ltd. All rights reserved.

  11. Indentation deformation and fracture of thin polystyrene films

    International Nuclear Information System (INIS)

    Li Min; Palacio, Manuel L.; Barry Carter, C.; Gerberich, William W.

    2002-01-01

    Nanoindentation-induced deformation and fracture of thin polystyrene (PS) films on glass substrates were characterized using visible-light microscopy and atomic force microscopy (AFM). Two film thicknesses, 2 and 3.5 μm were studied. It was difficult to induce delamination in the 2-μm film while the 3.5-μm film delaminated easily under indentation loads of 150 mN and higher. AFM cross-section analysis of the deformation and fracture geometry revealed that the ratio of the delamination radius to contact radius was between 3 and 4. Analysis of the fracture surface on the glass side indicates that substrate cracking acts as a trigger for initiation and propagation of interfacial cracks. Crack-arrest marks and process-zone marks were also observed by AFM imaging. The interfacial fracture toughness, or practical work of adhesion, was evaluated following two methods based on the indentation-induced delamination and a process-zone analysis. The fracture toughness was found to be approximately 0.6 J/m 2 for the 3.5-μm PS film on glass. AFM examination of the glass surface after indentation also showed fine flow lines around the indentation impression, indicating plastic deformation of glass

  12. Indentation deformation and fracture of thin polystyrene films

    Energy Technology Data Exchange (ETDEWEB)

    Li Min; Palacio, Manuel L.; Barry Carter, C.; Gerberich, William W

    2002-09-02

    Nanoindentation-induced deformation and fracture of thin polystyrene (PS) films on glass substrates were characterized using visible-light microscopy and atomic force microscopy (AFM). Two film thicknesses, 2 and 3.5 {mu}m were studied. It was difficult to induce delamination in the 2-{mu}m film while the 3.5-{mu}m film delaminated easily under indentation loads of 150 mN and higher. AFM cross-section analysis of the deformation and fracture geometry revealed that the ratio of the delamination radius to contact radius was between 3 and 4. Analysis of the fracture surface on the glass side indicates that substrate cracking acts as a trigger for initiation and propagation of interfacial cracks. Crack-arrest marks and process-zone marks were also observed by AFM imaging. The interfacial fracture toughness, or practical work of adhesion, was evaluated following two methods based on the indentation-induced delamination and a process-zone analysis. The fracture toughness was found to be approximately 0.6 J/m{sup 2} for the 3.5-{mu}m PS film on glass. AFM examination of the glass surface after indentation also showed fine flow lines around the indentation impression, indicating plastic deformation of glass.

  13. A microfluidic investigation of gas exsolution in glass and shale fracture networks

    Science.gov (United States)

    Porter, M. L.; Jimenez-Martinez, J.; Harrison, A.; Currier, R.; Viswanathan, H. S.

    2016-12-01

    Microfluidic investigations of pore-scale fluid flow and transport phenomena has steadily increased in recent years. In these investigations fluid flow is restricted to two-dimensions allowing for real-time visualization and quantification of complex flow and reactive transport behavior, which is difficult to obtain in other experimental systems. In this work, we describe a unique high pressure (up to 10.3 MPa) and temperature (up to 80 °C) microfluidics experimental system that allows us to investigate fluid flow and transport in geo-material (e.g., shale, Portland cement, etc.) micromodels. The use of geo-material micromodels allows us to better represent fluid-rock interactions including wettability, chemical reactivity, and nano-scale porosity at conditions representative of natural subsurface environments. Here, we present experimental results in fracture systems with applications to hydrocarbon mobility in fractured rocks. Complex fracture network patterns are derived from 3D x-ray tomography images of actual fractures created in shale rock cores. We use both shale and glass micromodels, allowing for a detailed comparison between flow phenomena in the different materials. We discuss results from two-phase gas (CO2 and N2) injection experiments designed to enhance oil recovery. In these experiments gas was injected into micromodels saturated with oil and allowed to soak for approximately 12 hours at elevated pressures. The pressure in the system was then decreased to atmospheric, causing the gas to expand and/or dissolve out of solution, subsequently mobilizing the oil. In addition to the experimental results, we present a relatively simple model designed to quantify the amount of oil mobilized as a function of decreasing system pressure. We will show comparisons between the experiments and model, and discuss the potential use of the model in field-scale reservoir simulations.

  14. Mechanical properties of nuclear waste glasses

    International Nuclear Information System (INIS)

    Connelly, A.J.; Hand, R.J.; Bingham, P.A.; Hyatt, N.C.

    2011-01-01

    The mechanical properties of nuclear waste glasses are important as they will determine the degree of cracking that may occur either on cooling or following a handling accident. Recent interest in the vitrification of intermediate level radioactive waste (ILW) as well as high level radioactive waste (HLW) has led to the development of new waste glass compositions that have not previously been characterised. Therefore the mechanical properties, including Young's modulus, Poisson's ratio, hardness, indentation fracture toughness and brittleness of a series of glasses designed to safely incorporate wet ILW have been investigated. The results are presented and compared with the equivalent properties of an inactive simulant of the current UK HLW glass and other nuclear waste glasses from the literature. The higher density glasses tend to have slightly lower hardness and indentation fracture toughness values and slightly higher brittleness values, however, it is shown that the variations in mechanical properties between these different glasses are limited, are well within the range of published values for nuclear waste glasses, and that the surveyed data for all radioactive waste glasses fall within relatively narrow range.

  15. Roman iron axes manufacturing technology

    International Nuclear Information System (INIS)

    Barrena, M.I.; Gomez de Salazar, J.M.; Soria, A.

    2008-01-01

    The results of metallographic, chemical and mechanical analysis of two Roman axes are presented. Insights into the technologies used by the Romans are considered. These axes were buried in a Roman village in La Olmeda, Palencia, Spain, which was built around the first century BC and it was later abandoned and destroyed in the fifth century AD. It has been observed that some artefacts, specifically axes show that the technology existed to increase hardness by solid-state welding of sheet steel of different carbon contents

  16. MANAGEMENT OF EXTRIMITY FRACTURE IN EMERGENCY DEPARTMENT

    Directory of Open Access Journals (Sweden)

    Putu Sukma Parahita

    2013-09-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE Fracture injuries in the extremities are accounted for 40% of the incidence of fractures in the United States and causes high morbidity (physical suffering, lost time, and mental stress. High-energy fractures of the lower limbs can also cause life threatening condition like major vascular injury, crush syndrome, and compartment syndrome. Initial treatment in the emergency room is essential to save lives and to save the fractured extremities. Primary survey (securing the airway, breathing and circulation and the secondary survey will be able to quickly and accurately identify dangerous early complication of fractures, such as major arterial injury, crush syndrome and compartment syndrome. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

  17. The Fulcum, the Late Roman and Byzantine Testudo: the Germanization of Roman Infantry Tactics?

    Directory of Open Access Journals (Sweden)

    Philip Rance

    2010-11-01

    Full Text Available The tactic of forming a shield-wall, although called by the Germanic name fulcum first in Maurice’s Strategicon in the sixth century, has a long history of use by the Roman legions, and is not an instance of Germanic influence on Roman tactics.

  18. THE EVOLUTION OF ROMAN FRONTIER CONCEPT AND POLICY

    Directory of Open Access Journals (Sweden)

    George Cupcea

    2015-03-01

    Full Text Available The Roman power is, ideologically, infinite in time and space. Nevertheless, the Roman state had experienced a wide variety of territorial limits, evolving in time and space, more or less throughout a millennium. If at first the Roman state, limited to Rome metropolitan area, later to the Italian peninsula, was easily defensible, beginning with the heavy expansion, also came trouble. The Romans, always innovating, find solutions for the fortification of the contact zones with the Barbarians. The Roman frontier concept was fundamentally different from the modern one. If the defence of Roman possessions was obviously priority, the border should remain an open ensemble, allowing for the free circulation of people and goods, some of the fundamental Roman rights. The peak of Roman expansion, 2nd century A.D. brings also the maximum development of the Empire frontier. Dacia overlaps widely chronologically on this trend, this being one of the reasons for one of the most complex frontier system in the Empire.

  19. Surface cracking in proton-irradiated glass

    International Nuclear Information System (INIS)

    Jensen, T.; Lawn, B.R.; Dalglish, R.L.; Kelly, J.C.

    1976-01-01

    Some observations are reported of the surface fracture behaviour of soda-lime glass slabs (6mm thick Pilkington float glass) irradiated with 480 kV protons. A simple indentation microfracture technique provided a convenient means of probing the irradiated surface regions. Basically, the technique involves loading a standard Vickers diamond pyramid indenter onto the area of interest such that a well-developed deformation/fracture pattern is generated. (author)

  20. Laser properties of an improved average-power Nd-doped phosphate glass

    International Nuclear Information System (INIS)

    Payne, S.A.; Marshall, C.D.; Bayramian, A.J.

    1995-01-01

    The Nd-doped phosphate laser glass described herein can withstand 2.3 times greater thermal loading without fracture, compared to APG-1 (commercially-available average-power glass from Schott Glass Technologies). The enhanced thermal loading capability is established on the basis of the intrinsic thermomechanical properties (expansion, conduction, fracture toughness, and Young's modulus), and by direct thermally-induced fracture experiments using Ar-ion laser heating of the samples. This Nd-doped phosphate glass (referred to as APG-t) is found to be characterized by a 29% lower gain cross section and a 25% longer low-concentration emission lifetime

  1. Influence of ageing on glass and resin bonding of dental glass-ceramic veneer adhesion to zirconia: A fracture mechanics analysis and interpretation.

    Science.gov (United States)

    Swain, M V; Gee, C; Li, K C

    2018-04-26

    Adhesion plays a major role in the bonding of dental materials. In this study the adhesion of two glass-ceramic systems (IPS e.max and VITABLOCS) to a zirconia sintered substrate using a glass (for IPS e.max) and resin (VITABLOCS) before and after exposure to ageing for 14 days in distilled water at 37 °C are compared using two interfacial fracture mechanics tests, the 3 point bend Schwickerath (Kosyfaki and Swain, 2014; Schneider and Swain, 2015) and 4 point bend (Charalambides et al., 1989) approaches. Both tests result in stable crack extension from which the strain energy release rate (G, N/m or J/m 2 ) can be determined. In the case of the 3 PB test the Work of Fracture was also determined. In addition, the Schwickerath test enables determination of the critical stress for the onset of cracking to occur, which forms the basis of the ISO (ISO9693-2:2016) adhesion test for porcelain ceramic adhesion to zirconia. For the aged samples there was a significant reduction in the resin-bonded strengths (Schwickerath) and strain energy release rate (both 3 and 4 PB tests), which was not evident for the glass bonded specimens. Critical examination of the force-displacement curves showed that ageing of the resin resulted in a major change in the form of the curves, which may be interpreted in terms of a reduction in the critical stress to initiate cracking and also in the development of an R-curve. The extent of the reduction in strain energy release rate following ageing was greater for the Schwickerath test than the Charalambides test. The results are discussed in terms of; the basic mechanics of these two tests, the deterioration of the resin bonding following moisture exposure and the different dimensions of the specimens. These in-vitro results raise concerns regarding resin bonding to zirconia. The present study uses a novel approach to investigate the role of ageing or environmental degradation on the adhesive bonding of two dental ceramics to zirconia

  2. Crack initiation and fracture features of Fe–Co–B–Si–Nb bulk metallic glass during compression

    Directory of Open Access Journals (Sweden)

    S. Lesz

    2016-01-01

    Full Text Available The aim of the paper was investigation crack initiation and fracture features developed during compression of Fe-based bulk metallic glass (BMG. These Fe-based BMG has received great attention as a new class of structural material due to an excellent properties (e.g. high strength and high elasticity and low costs. However, the poor ductility and brittle fracture exhibited in BMGs limit their structural application. At room temperature, BMGs fails catastrophically without appreciable plastic deformation under tension and only very limited plastic deformation is observed under compression or bending. Hence a well understanding of the crack initiation and fracture morphology of Fe-based BMGs after compression is of much importance for designing high performance BMGs. The raw materials used in this experiment for the production of BMGs were pure Fe, Co, Nb metals and nonmetallic elements: Si, B. The Fe–Co–B–Si–Nb alloy was cast as rods with three different diameters. The structure of the investigated BMGs rod is amorphous. The measurement of mechanical properties (Young modulus - E, compressive stress - σc, elastic strain - ε, unitary elastic strain energy – Uu were made in compression test. Compression test indicates the rods of Fe-based alloy to exhibit high mechanical strength. The development of crack initiation and fracture morphology after compression of Fe-based BMG were examined with scanning electron microscope (SEM. Fracture morphology of rods has been different on the cross section. Two characteristic features of the compressive fracture morphologies of BMGs were observed. One is the smooth region. Another typical feature of the compressive fracture morphology of BMGs is the vein pattern. The veins on the compressive fracture surface have an obvious direction as result of initial displace of sample along shear bands. This direction follows the direction of the displacement of a material. The formation of veins on the

  3. THE PHENOMENON OF ROMAN REPUBLICAN COINAGE IN PRE-ROMAN DACIA. A REXAMINATION OF THE EVIDENCE

    Directory of Open Access Journals (Sweden)

    Marius Grigore Stan

    2015-01-01

    Full Text Available This article offers a re-examination of the phenomenon of Roman Republican coinage during the pre-Roman period in Carpathian region. It is argued that by compiling the evidence into a multifaceted database, new insights are gained on the explanation of the currency in pre-Roman Dacia.Furthermore, the study employs statistical methods in an interdisciplinary approach to a better pinpoint the chronological point of entry for Republican denarii into the region. Due to the absence of archaeological context in many cases, coin hoards are the main focus of data collection.

  4. How to romanize Korean characters in international journals

    Directory of Open Access Journals (Sweden)

    Sun Huh

    2017-08-01

    Full Text Available For editors and manuscript editors, the romanization of Korean characters is a topic that should be understood thoroughly, because Korean proper nouns have become more widely used worldwide due to phenomena such as Hallyu (the Korean wave. In this report, I describe the 2 major romanization systems used in Korea: the Korean government’s romanization system and the McCune-Reischauer system. I also describe the transliteration guidelines presented in a variety of reference styles, such as the CSE (Council of Science Editors, ACS (American Chemical Society, AMA (American Medical Association, APA (American Psychological Association, IEEE (Institute of Electrical and Electronics Engineers styles and the NLM (National Library of Medicine style guide. I found that 2 journals have adopted the Korean government’s romanization system, while 10 use the McCune-Reischauer system. Other journals do not specifically mention a romanization system. Editors should select a romanization system and use it consistently. When presenting a reference that includes romanized text, the journal’s house style should be followed, based on international reference citation styles. Chinese characters in documents published in Korea should be romanized according to the Korean pronunciation.

  5. Nogle britiske romaner i 2007 - og en nobelpris

    DEFF Research Database (Denmark)

    Klitgård, Ebbe

    2008-01-01

    Genanmeldelse af Dorris Lessing, The Golden Notebook, nyanmeldelse af romaner af Anne Enright, Graham Swift, Ian McEwan og Jonathan Coe. Vurdering af den britiske romans "state of the arts" 2007. Udgivelsesdato: februar......Genanmeldelse af Dorris Lessing, The Golden Notebook, nyanmeldelse af romaner af Anne Enright, Graham Swift, Ian McEwan og Jonathan Coe. Vurdering af den britiske romans "state of the arts" 2007. Udgivelsesdato: februar...

  6. Roman Chamomile

    Science.gov (United States)

    ... eczema, frostbite, diaper rash, bedsores (decubitus ulcers), and hemorrhoids. Roman chamomile is sometimes mixed with other herbs ... gums. Liver and gallbladder problems. Frostbite. Diaper rash. Hemorrhoids. Other conditions. More evidence is needed to rate ...

  7. Crack tip fracture toughness of base glasses for dental restoration glass-ceramics using crack opening displacements.

    Science.gov (United States)

    Deubener, J; Höland, M; Höland, W; Janakiraman, N; Rheinberger, V M

    2011-10-01

    The critical stress intensity factor, also known as the crack tip toughness K(tip), was determined for three base glasses, which are used in the manufacture of glass-ceramics. The glasses included the base glass for a lithium disilicate glass-ceramic, the base glass for a fluoroapatite glass-ceramic and the base glass for a leucite glass-ceramic. These glass-ceramic are extensively used in the form of biomaterials in restorative dental medicine. The crack tip toughness was established by using crack opening displacement profiles under experimental conditions. The crack was produced by Vickers indentation. The crack tip toughness parameters determined for the three glass-ceramics differed quite significantly. The crack tip parameters of the lithium disilicate base glass and the leucite base glass were higher than that of the fluoroapatite base glass. This last material showed glass-in-glass phase separation. The discussion of the results clearly shows that the droplet glass phase is softer than the glass matrix. Therefore, the authors conclude that a direct relationship exists between the chemical nature of the glasses and the crack tip parameter. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Physical Property Investigation of Contemporary Glass lonomer and Resin Modified Glass lonomer Restorative Materials

    Science.gov (United States)

    2016-05-24

    selected physical properties of nine contemporary and recently-marketed glass-ionomer cement (GIC) and four resin-modified glass-ionomer cement {RMGIC...stainless steel molds. Testing was completed on a universal testing machine unt il failure. Knoop Hardness was obtained using fai led fracture toughness...address caries, function, biocompatibility, and minimal environmental impact. 2·3 Glass-ionomer cements were invented and developed by Wilson and Kent

  9. Mechanical properties of molybdenum-sealing glass-ceramics

    International Nuclear Information System (INIS)

    Swearengen, J.C.; Eagan, R.J.

    1975-07-01

    Elastic constants, thermal expansion, strength, and fracture toughness were determined for a molybdenum-sealing glass-ceramic containing approximately 31 volume percent Zn 2 SiO 4 crystals in a glass matrix. The microstructure was studied for two different crystallization treatments and moderate changes in composition. Mechanical properties of the composite were compared with the properties of the constituent phases through application of mixture theory and by fractographic observations. The reinforcing effects of the crystal phase at room temperature are evident in comparison with the properties of the residual glass but not necessarily in comparison with the parent glass. Fracture toughness of the composite depends primarily upon additive properties of the separate phases instead of by interactive effects such as microcracks. (U.S.)

  10. Ritual failure in Romans 6

    African Journals Online (AJOL)

    2016-08-05

    Aug 5, 2016 ... ISSN: (Online) 2072-8050, (Print) 0259-9422. Page 1 of ... understanding of Romans 6:1–14,2 where Paul develops his argument from an initial thesis statement ..... See Yarbro Collins (1989:42): 'Romans 6:1–14 the ritual of baptism is explicitly ..... his gospel of grace as antinomianism (Ferguson 2009:156;.

  11. Recent progress to understand stress corrosion cracking in sodium borosilicate glasses: linking the chemical composition to structural, physical and fracture properties

    Science.gov (United States)

    Rountree, Cindy L.

    2017-08-01

    This topical review is dedicated to understanding stress corrosion cracking in oxide glasses and specifically the SiO_2{\\text-B_2O_3{\\text-}Na_2O} (SBN) ternary glass systems. Many review papers already exist on the topic of stress corrosion cracking in complex oxide glasses or overly simplified glasses (pure silica). These papers look at how systematically controlling environmental factors (pH, temperature...) alter stress corrosion cracking, while maintaining the same type of glass sample. Many questions still exist, including: What sets the environmental limit? What sets the velocity versus stress intensity factor in the slow stress corrosion regime (Region I)? Can researchers optimize these two effects to enhance a glass’ resistance to failure? To help answer these questions, this review takes a different approach. It looks at how systemically controlling the glass’ chemical composition alters the structure and physical properties. These changes are then compared and contrasted to the fracture toughness and the stress corrosion cracking properties. By taking this holistic approach, researchers can begin to understand the controlling factors in stress corrosion cracking and how to optimize glasses via the initial chemical composition.

  12. Maestro Roman Toi kodumaal / Tiiu Pikkur

    Index Scriptorium Estoniae

    Pikkur, Tiiu, 1947-

    2007-01-01

    Helilooja ja koorijuht Roman Toi osalemisest muuseumiõhtul "Kaunimad laulud pühendan Sul!" 21. mail Eesti Teatri- ja Muusikamuuseumis, helilooja 90. sünnipäevale pühendatud kontserdist 23. mail Tallinna Toomkirikus ja Roman Toi nimelisest kirikulaulude konkursist

  13. The restoration of a maxillary central incisor fracture with the original crown fragment using a glass fiber-reinforced post: a clinical report.

    Science.gov (United States)

    Durkan, Rukiye Kaplan; Ozel, M Birol; Celik, Davut; Bağiş, Bora

    2008-12-01

    This report describes an esthetic, conservative, and economical alternative restoration technique for a fractured central incisor using the patient's own tooth crown piece and a bondable reinforcement glass fiber. Although the long-term durability of this adhesive post core restoration remains unknown, it remains successful after 1 year.

  14. Roman Lyariev, About Knives

    OpenAIRE

    Gedeeva, Darina; Ubushieva, Bamba; Babaev, Andrei

    2016-01-01

    Roman demonstrates and explains some of his hunting knives, including: -a knife made of a soft metal, -a foldable knife made of a hard metal and with a wooden handle, -a small foldable knife used for skinning animals, -a Swiss-style knife with a screwdriver, etc. He also shows diamond knife sharpeners and lanyards which are useful during hunting to dry clothes or to set up a tent. Most of these items have been given to Roman by his friends and relatives as presents. Arcadia

  15. Strengthened glass for high average power laser applications

    International Nuclear Information System (INIS)

    Cerqua, K.A.; Lindquist, A.; Jacobs, S.D.; Lambropoulos, J.

    1987-01-01

    Recent advancements in high repetition rate and high average power laser systems have put increasing demands on the development of improved solid state laser materials with high thermal loading capabilities. The authors have developed a process for strengthening a commercially available Nd doped phosphate glass utilizing an ion-exchange process. Results of thermal loading fracture tests on moderate size (160 x 15 x 8 mm) glass slabs have shown a 6-fold improvement in power loading capabilities for strengthened samples over unstrengthened slabs. Fractographic analysis of post-fracture samples has given insight into the mechanism of fracture in both unstrengthened and strengthened samples. Additional stress analysis calculations have supported these findings. In addition to processing the glass' surface during strengthening in a manner which preserves its post-treatment optical quality, the authors have developed an in-house optical fabrication technique utilizing acid polishing to minimize subsurface damage in samples prior to exchange treatment. Finally, extension of the strengthening process to alternate geometries of laser glass has produced encouraging results, which may expand the potential or strengthened glass in laser systems, making it an exciting prospect for many applications

  16. The signed Roman domatic number of a digraph

    Directory of Open Access Journals (Sweden)

    Seyed Mahmoud Sheikholeslami

    2015-03-01

    Full Text Available Let $D$ be a finite and simple digraph with vertex set $V(D$.A {\\em signed Roman dominating function} on the digraph $D$ isa function  $f:V (D\\longrightarrow \\{-1, 1, 2\\}$ such that$\\sum_{u\\in N^-[v]}f(u\\ge 1$ for every $v\\in V(D$, where $N^-[v]$ consists of $v$ andall inner neighbors of $v$, and every vertex $u\\in V(D$ for which $f(u=-1$ has an innerneighbor $v$ for which $f(v=2$. A set $\\{f_1,f_2,\\ldots,f_d\\}$ of distinct signedRoman dominating functions on $D$ with the property that $\\sum_{i=1}^df_i(v\\le 1$ for each$v\\in V(D$, is called a {\\em signed Roman dominating family} (of functions on $D$. The maximumnumber of functions in a signed Roman dominating family on $D$ is the {\\em signed Roman domaticnumber} of $D$, denoted by $d_{sR}(D$. In this paper we initiate the study of signed Romandomatic number in digraphs and we present some sharp bounds for $d_{sR}(D$. In addition, wedetermine the signed Roman domatic number of some digraphs.  Some of our results are extensionsof well-known properties of the signed Roman domatic number of graphs.

  17. COUNTERFEITING ROMAN COINS IN THE ROMAN EMPIRE I – III A.D. STUDY ON THE ROMAN PROVINCES OF DACIA AND PANNONIA

    Directory of Open Access Journals (Sweden)

    Razvan Bogdan Gaspar

    2015-12-01

    Full Text Available This paper is based on the study of Roman silver coins, from archaeological sites located in Roman Dacia and Pannonia. Initially centred on the record of hybrid silver coins, the paper expanded its analysis on counterfeit pieces as well in order to fully understand all problems of roman silver coinage from the 1stto the 3rd centuries AD.The new and larger area of research had more than one implications, coin distribution on the studied sites, influx of coin in the province, quantity of recorded counterfeited pieces being just some of them. Thus every situation was discussed in different chapters, first presenting the coins and the laws that protected them, the studied sites and the analyse of the silver coins on these sites, the general and compared situation between the provinces, interpretation of the counterfeited and hybrid pieces and finally, conclusions on the subject.All these tasks have been achieved one step at a time, each archaeological site providing precious data which piled up and was finally pressed in order to present the correct historical situation.

  18. Mixed mode fracture of dental interfaces

    International Nuclear Information System (INIS)

    Rahbar, Nima; Yang, Yong; Soboyejo, Winston

    2008-01-01

    This paper presents the results of a combined experimental and computational study of mixed mode fracture in glass/cement and zirconia/cement interfaces that are relevant to dental restorations. The interfacial fracture is investigated using Brazil-nut specimens. The kinking in-and-out of the interface that occurs between glass/cement and zirconia/cement interfaces, is also shown to be consistent with predictions from a microstructure-based finite element model. The predictions later verified using focused ion beam and scanning electron microscopy images

  19. Numerical simulations of glass impacts using smooth particle hydrodynamics

    International Nuclear Information System (INIS)

    Mandell, D.A.; Wingate, C.A.

    1995-01-01

    As part of a program to develop advanced hydrocode design tools, we have implemented a brittle fracture model for glass into the SPHINX smooth particle hydrodynamics code. We have evaluated this model and the code by predicting data from one-dimensional flyer plate impacts into glass. Since fractured glass properties, which are needed in the model, are not available, we did sensitivity studies of these properties, as well as sensitivity studies to determine the number of particles needed in the calculations. The numerical results are in good agreement with the data

  20. Subcritical fracture propagation in rocks: An examination using the methods of fracture mechanics and non-destructive testing. Ph.D. Thesis

    Science.gov (United States)

    Swanson, P. L.

    1984-01-01

    An experimental investigation of tensile rock fracture is presented with an emphasis on characterizing time dependent crack growth using the methods of fracture mechanics. Subcritical fracture experiments were performed in moist air on glass and five different rock types at crack velocities using the double torsion technique. The experimental results suggest that subcritical fracture resistance in polycrystals is dominated by microstructural effects. Evidence for gross violations of the assumptions of linear elastic fracture mechanics and double torsion theory was found in the tests on rocks. In an effort to obtain a better understanding of the physical breakdown processes associated with rock fracture, a series of nondestructive evaluation tests were performed during subcritical fracture experiments on glass and granite. Comparison of the observed process zone shape with that expected on the basis of a critical normal principal tensile stress criterion shows that the zone is much more elongated in the crack propagation direction than predicted by the continuum based microcracking model alone.

  1. Fracture Strength of Fused Silica From Photonic Signatures Around Collision Sites

    Science.gov (United States)

    Yost, William T.; Cramer, K Elliott

    2015-01-01

    Impact sites in glass affect its fracture strength. An analytical model that predicts fracture strength from grey-field polariscope (GFP) readings (photoelastic retardations) has been developed and reported in the literature. The model is suggestive that stress fields, resulting from impact damage, destablizes sites within the glass, which lead to pathways that cause strength degradation. Using data collected from fused silica specimens fabricated from outer window panes that were designed for the space shuttle, the model was tested against four categories of inflicted damage. The damage sites were cored from the window carcasses, examined with the GFP and broken using the ASTM Standard C1499-09 to measure the fracture strength. A correlation is made between the fracture strength and the photoelastic retardation measured at the damage site in each specimen. A least-squares fit is calculated. The results are compared with the predictions from the model. A plausible single-sided NDE damage site inspection method (a version of which is planned for glass inspection in the Orion Project) that relates photoelastic retardation in glass components to its fracture strength is presented.

  2. Methods for Measurement and Statistical Analysis of the Frangibility of Strengthened Glass

    Directory of Open Access Journals (Sweden)

    Zhongzhi eTang

    2015-06-01

    Full Text Available Chemically strengthened glass features a surface compression and a balancing central tension (CT in the interior of the glass. A greater CT is usually associated with a higher level of stored elastic energy in the glass. During a fracture event, release of a greater amount of stored energy can lead to frangibility, i.e., shorter crack branching distances, smaller fragment size, and ejection of small fragments from the glass. In this paper, the frangibility and fragmentation behaviors of a series of chemically strengthened glass samples are studied using two different manual testing methods and an automated tester. Both immediate and delayed fracture events were observed. A statistical method is proposed to determine the probability of frangible fracture for glasses ion exchanged under a specific set of conditions, and analysis is performed to understand the dependence of frangibility probability on sample thickness, CT, and testing method. We also propose a more rigorous set of criteria for qualifying frangibility.

  3. Fe++/Fe+++ concentration relationship and mechanical properties of phosphate glasses useful for wastes immobilization

    International Nuclear Information System (INIS)

    Garcia, D.A.; Prado, Miguel O.

    2007-01-01

    Under different melting conditions, glasses with different Fe(II)/Fe(III) concentration relationship were prepared within each type of glass 43Fe 2 O 3 -57P 2 O 5 and 33,33Fe 2 O 3 - 66,67P 2 O 5 . Using Moessbauer spectroscopy Fe(II)/Fe(III) concentration values were determined. Vickers and Knoop indentations were used for determining their hardness, toughness, Young modulus and brittleness. The same measurements were carried on some silicate and aluminosilicate glasses. Also Weibull statistics was done to determine the characteristics (Weibull modulus and and fracture probability) of glass fracture. We found that silicate glasses (SG) are harder than phosphate glasses (PG). Toughness values for PG, are in the same range than for SG, although for the same density exhibit larger values or smaller brittleness than silicate glasses. For one of the glasses it was found that the mechanical load P 0 needed for a fracture probability of 63% increases with the Fe(II) content. (author)

  4. Soda-Lime-Silicate Float Glass: A Property Comparison

    Science.gov (United States)

    2017-10-01

    temperature. West Conshohocken (PA): ASTM International; 2012. 4. Quinn GD, Swab JJ . Fracture toughness of glasses as measured by the SCF and SEPB methods...Swab JJ , Patel PJ, Tran X, Gilde L, Luoto E, Gaviola MH, Gott A, Paulson B, Kilczewski S. Equibiaxial flexure strength of glass: influence of glass

  5. Medicine in Balkans during the Roman Period.

    Science.gov (United States)

    Baykan, Daniş

    2017-08-04

    The aim of this study is to investigate the archaeological finds to enlighten the medical methods of treatments and operations applied in Balkans during Roman Period. Some independent local and regional find groups, taken from existing publications will be grouped together and a holistic point-of-view will be taken against medicine in Balkan Geography during Roman Period. Due to basic differences it contained, the data before Roman Period are excluded. Most of Greece and Aegean Islands are also excluded since the topic selected is "Medicine of Roman Period." Greece and Aegean Islands should be evaluated in another study in connection with West Anatolia which is closer than the Balkan Geography in terms of social relations. The spread of medical tools in Balkans during Roman Period is concentrated around military garrisons, and in settlements built around military pathways, and in settlements containing an amphitheater associated with gladiators. This spread is verified by the studies on Bulgaria in general. The data is also compatible with the assertion suggesting that the amount of application of pharmaceutical treatment increases when one moves away from the military centres.

  6. Roman contre roman dans l’organisation du manuscrit du Vatican, Regina Latina 1725

    Directory of Open Access Journals (Sweden)

    Francis Gingras

    2012-08-01

    Full Text Available Alors que les développements structuralistes et post-structuralistes ont favorisé la “textualisation” de la littérature médiévale, l’auteur suggère que la recontextualisation de la réception du roman médiéval passe par un retour aux manuscrits. Appliquée au manuscrit du Vatican, Regina Latina 1725, cette hypothèse de recherche révèle une technique de contrepoint que permet la juxtaposition de différents romans et dont, en dernier recours, le lecteur est toujours un peu juge.

  7. Critical fatigue behaviour in brittle glasses

    Indian Academy of Sciences (India)

    Unknown

    Abstract. The dynamic fatigue fracture behaviour in different glasses under various sub-threshold loading conditions are analysed here employing an anomalous diffusion model. Critical dynamical behaviour in the time-to-fracture and the growth of the micro-crack sizes, similar to that observed in such materials in the case.

  8. [Microstructure and mechanical property of a new IPS-Empress 2 dental glass-ceramic].

    Science.gov (United States)

    Luo, Xiao-ping; Watts, D C; Wilson, N H F; Silsons, N; Cheng, Ya-qin

    2005-03-01

    To investigate the microstructure and mechanical properties of a new IPS-Empress 2 dental glass-ceramic. AFM, SEM and XRD were used to analyze the microstructure and crystal phase of IPS-Empress 2 glass-ceramic. The flexural strength and fracture toughness were tested using 3-point bending method and indentation method respectively. IPS-Empress 2 glass-ceramic mainly consisted of lithium disilicate crystal, lithium phosphate and glass matrix, which formed a continuous interlocking structure. The crystal phases were not changed before and after hot-pressed treatment. AFM showed nucleating agent particles of different sizes distributed on the highly polished ceramic surface. The strength and fracture toughness were 300 MPa and 3.1 MPam(1/2). The high strength and fracture toughness of IPS-Empress 2 glass ceramic are attributed to the fine lithium disilicate crystalline, interlocking microstructure and crack deflection.

  9. Treatment of root fracture with accompanying resorption using cermet cement.

    Science.gov (United States)

    Lui, J L

    1992-02-01

    A method of treating an apical root fracture with accompanying resorption at the junction of the fracture fragments using glass-cermet cement is described. Endodontically, the material had previously been used for repair of lateral resorptive root defects and retrograde root fillings. Complete bone regeneration was observed three years post-operatively following treatment of the root fracture in the conventional manner. The various advantages of glass-cermet cement as a root filling material used in the technique described are discussed.

  10. Treatment of tooth fracture by medium-energy CO2 laser and DP-bioactive glass paste: the interaction of enamel and DP-bioactive glass paste during irradiation by CO2 laser.

    Science.gov (United States)

    Lin, C P; Tseng, Y C; Lin, F H; Liao, J D; Lan, W H

    2001-03-01

    Acute trauma or trauma associated with occlusal disturbance can produce tooth crack or fracture. Although several methods are proposed to treat the defect, however, the prognosis is generally poor. If the fusion of a tooth fracture by laser is possible, it will offer an alternative to extraction or at least serve as an adjunctive treatment in the reconstruction. We have tried to use a continuous-wave CO2 laser and a newly developed DP-bioactive glass paste (DPGP) to fuse or bridge tooth crack or fracture lines. Both the DP-bioactive glass paste and tooth enamel have strong absorption bands at the wavelength of 10.6 microm. Therefore, under CO2 laser, DPGP and enamel should have an effective absorption and melt together. The interface between DPGP and enamel could be regarded as a mixture of DPGP and enamel (DPG-E). The study focused on the phase transformation, microstructure, functional group and thermal behavior of DPG-E with or without CO2 laser irradiation, by the analytical techniques of XRD, FTIR, DTA/TGA, and SEM. The results of XRD showed that the main crystal phase in the DPG-E was dicalcium phosphate dihydrate (CaHPO4.2H2O). It changed into CaHPO4, gamma-Ca2P2O7, beta-Ca2P2O7 and finally alpha-Ca2P2O7 with increasing temperature. In the FTIR analysis, the 720 cm(-1) absorption band ascribed to the P-O-P linkage in pyrophosphate rose up and the intensities of the OH- bands reduced after laser irradiation. In regard to the results of DTA/TGA after irradiation, the weight loss decreased due to the removal of part of absorption water and crystallization water by the CO2 laser. SEM micrographs revealed that the melted masses and the plate-like crystals formed a tight chemical bond between the enamel and DPGP. We expect that DPGP with the help of CO2 laser can be an alternative to the treatment of tooth crack or fracture.

  11. Medieval and early modern approaches to fractures of the proximal humerus

    DEFF Research Database (Denmark)

    Brorson, S.

    2010-01-01

    The diagnosis and management of complex fractures of the proximal humerus have challenged surgical practitioners and medical writers since the earliest recorded surgical texts. Current knowledge of fractures of the proximal humerus has been obtained through pathoanatomical and biomechanical studies...... within the last two centuries. However, the historical preconditions for this development have not been studied. This paper reviews written sources from the fall of the Roman Empire to the late eighteenth century. Medieval and early modern writers mainly rely on the Hippocratic writings De Fracturis...

  12. Mechanical Properties of a High Lead Glass Used in the Mars Organic Molecule Analyzer

    Science.gov (United States)

    Salem, Jonathan A.; Smith, Nathan A.; Ersahin, Akif

    2015-01-01

    The elastic constants, strength, fracture toughness, slow crack growth parameters, and mirror constant of a high lead glass supplied as tubes and funnels were measured using ASTM International (formerly ASTM, American Society for Testing and Materials) methods and modifications thereof. The material exhibits lower Young's modulus and slow crack growth exponent as compared to soda-lime silica glass. Highly modified glasses exhibit lower fracture toughness and slow crack growth exponent than high purity glasses such as fused silica.

  13. Parametrization in models of subcritical glass fracture: Activation offset and concerted activation

    Science.gov (United States)

    Rodrigues, Bruno Poletto; Hühn, Carolin; Erlebach, Andreas; Mey, Dorothea; Sierka, Marek; Wondraczek, Lothar

    2017-08-01

    There are two established but fundamentally different empirical approaches to parametrize the rate of subcritical fracture in brittle materials. While both are relying on a thermally activated reaction of bond rupture, the difference lies in the way as to how the externally applied stresses affect the local energy landscape. In the consideration of inorganic glasses, the strain energy is typically taken as an off-set on the activation barrier. As an alternative interpretation, the system’s volumetric strain-energy is added to its thermal energy. Such an interpretation is consistent with the democratic fiber bundle model. Here, we test this approach of concerted activation against macroscopic data of bond cleavage activation energy, and also against ab initio quantum chemical simulation of the energy barrier for cracking in silica. The fact that both models are able to reproduce experimental observation to a remarkable degree highlights the importance of a holistic consideration towards non-empirical understanding.

  14. Single Finds. The case of Roman Egypt

    DEFF Research Database (Denmark)

    Christiansen, Erik

    2006-01-01

    Survery of single or stray finds from Roman Egypt and discussion of them as evidence for the circulation and use of coins......Survery of single or stray finds from Roman Egypt and discussion of them as evidence for the circulation and use of coins...

  15. The ALFA Roman Pot Detectors of ATLAS

    CERN Document Server

    Abdel Khalek, S.

    2016-11-23

    The ATLAS Roman Pot system is designed to determine the total proton-proton cross-section as well as the luminosity at the Large Hadron Collider (LHC) by measuring elastic proton scattering at very small angles. The system is made of four Roman Pot stations, located in the LHC tunnel in a distance of about 240~m at both sides of the ATLAS interaction point. Each station is equipped with tracking detectors, inserted in Roman Pots which approach the LHC beams vertically. The tracking detectors consist of multi-layer scintillating fibre structures readout by Multi-Anode-Photo-Multipliers.

  16. Celtiberian metrology and its romanization

    Directory of Open Access Journals (Sweden)

    Leonard A. CURCHIN

    2013-05-01

    Full Text Available Celtiberian metrology has scarcely been investigated until now, with the exception of coin weights. On the basis of measurements of pre-Roman mud bricks, a Celtiberian foot of 24 cm is proposed. With regard to weights, we can accept a module of 9 g for silver jewelry and some bronze coins; however, loom weights do not conform to any metrological system. Over time, Roman measures of length (as indicated by the dimensions of bricks, tiles and architectural monuments and weight were adopted.

  17. Preliminary Simulation of the Corrosion Rate of Archaeological Glass

    Energy Technology Data Exchange (ETDEWEB)

    Steefel, Carl

    2014-01-06

    In this study, we make use of a micro-continuum modeling approach (the Kinetic-Microscopic-Continuum Model or K{micro}C model) to capture the spatial distribution and identity of reaction products developing over time as a result of the archaeological glass corrosion, while also matching the time scales of alteration where possible. Since the glass blocks sat on the Mediterranean seafloor for 1800 years, the physical and chemical boundary conditions are largely constant. We focus on a fracture within the glass block identified by Verney-Carron et al. (2008) and simulate it as a 1D system, with a fixed concentration (Dirichlet) boundary corresponding to the interior of the fracture.

  18. Corrosion of synthesized glasses and glazes as analogs for nuclear waste glass degradation

    International Nuclear Information System (INIS)

    Vandiver, P.B.

    1994-01-01

    Synthesized glasses provide an opportunity to study natural corrosion processes which are intermediate in time span between geological examples of natural glasses, such as obsidians and tektites, and relatively short term laboratory tests lasting a few hours to several decades. In addition, synthesized glasses can usually be tracked to particular archaeological find sites with known dates of production and often burial. Environmental conditions are routinely measured at archaeological sites as a part of the excavation-process, such that information is available on the yearly cycling of temperature and relative humidity, sometimes at the depth at which the artifact was found. Whether the artifacts were excavated in an air enclosure, such as a tomb, or in the soil can also be reconstructed, such that one can determine whether aqueous or atmospheric corrosion was involved in the degradation process. For instance, so-called open-quotes Roman glassclose quotes may span a time period of production of 800 years and a geographical range from Germany to North Africa and from Britain to Afghanistan. One example is the storage during World War II of glass from the British Museum in underground metro stations. Some of these glasses have been in collections for over 100 years. Thus, populations of glasses can be chosen for experimentation which compare variations in bulk composition, dopants, microstructure, heat treatment, ground vs. fire polished surfaces, aqueous vs. atmospheric corrosion, geographic, geological as well as recent storage conditions. Glasses in museums are generally considered to have had their corrosion arrested and be stable because changes in visual appearance are not obvious. However, if we attempt to measure the range of surface water content in these glasses using Fourier transform infrared analysis, a considerable variability is found, as shown

  19. Analysis of archaeological ceramics and glass samples by microPIXE and LA-ICP-MS methods

    International Nuclear Information System (INIS)

    Uzonyi, I.; Elekes, Z.; Kiss, A.Z.

    1999-01-01

    The availability of a proton microprobe at ATOMKI and LA-ICP-MS and SEM techniques at the French institutes made it possible to start a joint research of archaeological ceramics and glass samples in the framework of COST-GI program about one year ago. Concerning ceramics the task has been the determination of provenance of some roman amphorae samples. In another project glass samples found in the royal palaces of Buda and Visegrad were analyzed. The results may be utilized both in exact dating and determination of provenance of glass artefacts of unknown origin. (K.A.)

  20. Sealed glass coating of high temperature ceramic superconductors

    Science.gov (United States)

    Wu, Weite; Chu, Cha Y.; Goretta, Kenneth C.; Routbort, Jules L.

    1995-01-01

    A method and article of manufacture of a lead oxide based glass coating on a high temperature superconductor. The method includes preparing a dispersion of glass powders in a solution, applying the dispersion to the superconductor, drying the dispersion before applying another coating and heating the glass powder dispersion at temperatures below oxygen diffusion onset and above the glass melting point to form a continuous glass coating on the superconductor to establish compressive stresses which enhance the fracture strength of the superconductor.

  1. Biopolitics rudiments in Roman Law

    Directory of Open Access Journals (Sweden)

    Miguel Régio de Almeida

    2014-12-01

    Full Text Available This article proposes a jurisprudential and philosophical reflection on Biopolitics in Roman Law, based on juridical figures such as sacred men, aliens, slaves and iustitium. Working at the edge of roman society, they represent a relation of inclusion or tolerance in a World centred on its citizens, which led to a state of exception or to integration modes of this marginality. Lessons for the present time can still be learned from this dynamic, when a new ius commune is proposed.http://dx.doi.org/10.14195/2183-1718_66_11

  2. Fatigue resistance of 2 different CAD/CAM glass-ceramic materials used for single-tooth implant crowns.

    Science.gov (United States)

    Çavuşoğlu, Yeliz; Sahin, Erdal; Gürbüz, Riza; Akça, Kivanç

    2011-10-01

    To evaluate the fatigue resistance of 2 different CAD/CAM in-office monoceramic materials with single-tooth implant-supported crowns in functional area. A metal experimental model with a dental implant was designed to receive in-office CAD/CAM-generated monoceramic crowns. Laterally positioned axial dynamic loading of 300 N at 2 Hz was applied to implant-supported crowns machined from 2 different glass materials for 100,000 cycle. Failures in terms of fracture, crack formation, and chipping were macroscopically recorded and microscopically evaluated. Four of 10 aluminasilicate glass-ceramic crowns fractured at early loading cycles, the rest completed loading with a visible crack formation. Crack formation was recorded for 2 of 10 leucite glass-ceramic crowns. Others completed test without visible damage but fractured upon removal. Lack in chemical adhesion between titanium abutment and dental cement likely reduces the fatigue resistance of machinable glass-ceramic materials. However, relatively better fractural strength of leucite glass-ceramics could be taken into consideration. Accordingly, progress on developmental changes in filler composition of glass-ceramics may be promising. Machinable glass-ceramics do not possess sufficient fatigue resistance for single-tooth implant crowns in functional area.

  3. Greco-Roman Astrology

    Science.gov (United States)

    Beck, Roger

    Astrology was entrenched in the culture of the Roman Empire. The system and its influence is described as well as its relationship to mathematical astronomy at the time. The material remains are of two sorts: papyrus horoscopes and coins with astrological motifs.

  4. Dea Computrix - another deity for the Roman Pantheon? Journeys in the Roman Empire CD-Rom

    Directory of Open Access Journals (Sweden)

    T. Sam N. Moorhead

    2002-08-01

    Full Text Available This article outlines a personal view on the content and production of a CD-Rom on the Roman world produced by The British Museum, Channel 4, Verulamium Museum and Braunarts: Journeys in the Roman Empire. I discuss some of the benefits of and problems with multimedia production and outline feedback from various evaluation projects of the CD-Rom. I also briefly discuss the future of CD-Roms in the face of a rapidly expanding internet with reference to other multimedia projects at The British Museum.

  5. Flaubert lecteur de romans historiques

    Directory of Open Access Journals (Sweden)

    Bernard Gendrel

    2009-12-01

    Full Text Available Les notes de lectures de Flaubert dans sa correspondance permettent de dégager deux types de romans historiques : le roman à sujet ancien, qui se doit, pour être vraisemblable, d'éloigner les personnages en réduisant la part d'explications psychologiques, et le roman à sujet contemporain, qui au contraire allie prise de distance (historique ou sociale et rapprochement (psychologique. Victor Hugo excellerait dans le premier mais pas dans le second. Quant à Flaubert, son obsession sera de réussir dans les deux.Flaubert’s reading notes in his correspondence allow us to identify two types of historical novels: the novel with an ancient subject, which, to be plausible, must keep characters at a distance and limit psychological explanations, and the novel with a contemporary subject which, on the contrary, both keeps aloof from historical or social questions and draws nearer to psychological questions. Victor Hugo excelled in the first but not in the second posture.  As for Flaubert, his obsession was be to be successful in both.

  6. Magma fracturing and degassing associated with obsidian formation: The explosive–effusive transition

    Science.gov (United States)

    Cabrera, Agustin; Weinberg, Roberto; Wright, Heather M.

    2015-01-01

    This paper explores the role of melt fracturing in degassing rhyolitic volcanic systems. The Monte Pilato-Rocche Rosse eruptions in Italy evolved from explosive to effusive in style, and H2O content in quenched glasses changed over time from relatively H2O-rich (~ 0.90 wt.%) to H2O-poor dense obsidian (~ 0.10–0.20 wt.%). In addition, healed fractures have been recorded in all different eruptive materials, from the glass of early-erupted tube pumice and rinds of breadcrusted obsidian pyroclasts, to the glass of late-erupted dense obsidian pyroclasts, and throughout the final effusive Rocche Rosse lava flow. These rocks show multiple fault sets, some with crenulated fault planes indicating resumption of viscous flow after faulting, complex obsidian breccias with evidence for post-brecciation folding and stretching, and centimetre- to metre-thick tuffisite preserved in pyroclasts and lava, representing collapsed foam due to fracturing of vesicle walls. These microstructural observations indicate that multiple fracturing and healing events occurred during both explosive and effusive eruptions. H2O content in glass decreases by as much as 0.14 wt.% towards healed fractures/faults and decreases in stretched obsidian breccias towards regions of intense brecciation. A drop in pressure and/or increase in temperature along fractures caused diffusive H2O migration through melt towards fracture surfaces. Repetitive and pervasive fracturing and healing thereby create conditions for diffusive H2O loss into fractures and subsequent escape through permeable paths. This type of progressive magma degassing provides a potential mechanism to explain the formation of dense obsidian and the evolution from explosive to effusive eruption style.

  7. Fracture resistance of class IV fiber-reinforced composite resin restorations: An in vitro study

    Directory of Open Access Journals (Sweden)

    P S Praveen Kumar

    2017-01-01

    Full Text Available Objectives: The aim of this study was to evaluate fracture resistance of incisal edge fractures (Class IV restored with a Glass Fiber-reinforced Composite (FRC. Materials and Methods: Twenty-four extracted sound maxillary central incisors were randomly divided into two groups. Group I (control contained untreated teeth. Samples in experimental groups II were prepared by cutting the incisal (one-third part of the crown horizontally and was subjected to enamel preparations, then restored with a Glass FRC. Fracture resistance was evaluated as Newton's for samples tested in a Hounsfield universal testing machine. Failure modes were examined microscopically. Results: Mean peak failure load (Newton's observed in Glass Fiber-reinforced Nanocomposite was 863.50 ± 76.12. The experimental group showed similar types of failure modes with the majority occurring as cohesive and mixed type. 58% of the teeth in Glass FRC group fractured below the cementoenamel junction. Conclusion: Using Fiber reinforced composite substructure under conventional composites in Class IV restorations, the fracture resistance of the restored incisal edge could be increased.

  8. Potential prospects in archaeological research by using optical spectroscopy through a black glass ocular

    Science.gov (United States)

    Cosyns, P.; Meulebroeck, W.; Thienpont, H.; Nys, K.

    The aim of this paper is to draw attention to the potential usefulness of optical spectroscopy within the archaeological discourse. We therefore use the standardized color coordinates and the transmittance spectra in the region between 350- 1650 nm of nine fragmented Roman black glass artifacts from archaeological contexts in Avenches (Switzerland) and an intact piece from Tongeren (Belgium). Firstly, we demonstrate how the use of UV-Vis-NIR spectroscopy can help the archaeologist in understanding the various excavated features containing glass artifacts. The analysis of the optical spectra of Roman black glass artifacts demonstrates in the first place that an object has a very homogenous composition. The clustering of the different fragments with characteristic spectra permits to connect the pieces from various areas of an excavation to one single object or to several objects from the same batch. These results provide the archaeologist the possibility to merge recognized layers or to connect different features in the surrounding area. Secondly, we demonstrate how the use of UV-Vis-NIR spectroscopy can help improve the analysis process. This inexpensive method can facilitate a more convenient and purposive sampling by means of a preliminary inquiry, selecting the most interesting pieces out of a large group of artifacts suitable for chemical analysis.

  9. The Cult of the Roman Emperor before and after Christianity

    DEFF Research Database (Denmark)

    Warmind, Morten

    1993-01-01

    This paper is concerned with a complete set of rituals and certain connected ideas, namely the Roman emperor-cult, that had survived the change of religion from Roman religion to Christianity. The rituals endure, even while their mythological basis is perishing. The emperor-cult includes the ritu......This paper is concerned with a complete set of rituals and certain connected ideas, namely the Roman emperor-cult, that had survived the change of religion from Roman religion to Christianity. The rituals endure, even while their mythological basis is perishing. The emperor-cult includes...

  10. Improvement of the mode II interface fracture toughness of glass fiber reinforced plastics/aluminum laminates through vapor grown carbon fiber interleaves.

    Science.gov (United States)

    Ning, Huiming; Li, Yuan; Hu, Ning; Cao, Yanping; Yan, Cheng; Azuma, Takesi; Peng, Xianghe; Wu, Liangke; Li, Jinhua; Li, Leilei

    2014-06-01

    The effects of acid treatment, vapor grown carbon fiber (VGCF) interlayer and the angle, i.e., 0° and 90°, between the rolling stripes of an aluminum (Al) plate and the fiber direction of glass fiber reinforced plastics (GFRP) on the mode II interlaminar mechanical properties of GFRP/Al laminates were investigated. The experimental results of an end notched flexure test demonstrate that the acid treatment and the proper addition of VGCF can effectively improve the critical load and mode II fracture toughness of GFRP/Al laminates. The specimens with acid treatment and 10 g m -2 VGCF addition possess the highest mode II fracture toughness, i.e., 269% and 385% increases in the 0° and 90° specimens, respectively compared to those corresponding pristine ones. Due to the induced anisotropy by the rolling stripes on the aluminum plate, the 90° specimens possess 15.3%-73.6% higher mode II fracture toughness compared to the 0° specimens. The improvement mechanisms were explored by the observation of crack propagation path and fracture surface with optical, laser scanning and scanning electron microscopies. Moreover, finite element analyses were carried out based on the cohesive zone model to verify the experimental fracture toughness and to predict the interface shear strength between the aluminum plates and GFRP laminates.

  11. Late-Roman glass bowl with drops and cabochons from Guarromán, Jaén | El cuenco de vidrio tardorromano con gotas y cabujones de Guarromán, Jaén

    Directory of Open Access Journals (Sweden)

    María José Almagro Gorbea

    2010-12-01

    Full Text Available The Museo Nacional de Artes Decorativas (Madrid has a beautiful glass bowl decorated with coloured drops, which has never been studied. This was a very popular type of glassware all over the Roman world, especially in Gaul and the Rhineland, but also in other Roman provinces. Numerous pieces were manufactured with this design and occasionally they were also copied in large series of lower quality to satisfy the mass market. In the twentieth century, few vases of this type were known in Spain and they had not been studied in depth, so they were considered luxury imports. However, recent excavations and studies have verified that they were also very common in Hispania in the fourth and fifth centuries A.D. | La colección de vidrios romanos del Museo Nacional de Artes Decorativas posee un vaso decorado con cabujones de colores que nunca ha sido debidamente publicado. Este tipo de vasos tuvo gran aceptación en las manufacturas de vidrio por todo el Imperio romano, especialmente en las Galias y Renania, pero también en otras regiones se fabricaron piezas con estos motivos, a veces de baja calidad, para satisfacer a una clientela popular. En el siglo XX eran escasos los vasos españoles conocidos de esta clase y no estaban bien estudiados, por lo que se consideraban piezas importadas de lujo. En los últimos años, recientes excavaciones y estudios han evidenciado que fueron piezas corrientes en las vajillas de Hispania durante los siglos IV-V d.C.

  12. Taylor impact of glass rods

    International Nuclear Information System (INIS)

    Willmott, G.R.; Radford, D.D.

    2005-01-01

    The deformation and fracture behavior of soda-lime and borosilicate glass rods was examined during classic and symmetric Taylor impact experiments for impact pressures to 4 and 10 GPa, respectively. High-speed photography and piezoresistive gauges were used to measure the failure front velocities in both glasses, and for impact pressures below ∼2 GPa the failure front velocity increases rapidly with increasing pressure. As the pressure was increased above ∼3 GPa, the failure front velocities asymptotically approached maximum values between the longitudinal and shear wave velocities of each material; at ∼4 GPa, the average failure front velocities were 4.7±0.5 and 4.6±0.5 mm μs -1 for the soda-lime and borosilicate specimens, respectively. The observed mechanism of failure in these experiments involved continuous pressure-dependent nucleation and growth of microcracks behind the incident wave. As the impact pressure was increased, there was a decrease in the time to failure. The density of cracks within the failed region was material dependent, with the more open-structured borosilicate glass showing a larger fracture density

  13. Glass forming ability and mechanical properties of Zr50Cu42Al8 bulk metallic glass

    International Nuclear Information System (INIS)

    Xia, L; Chan, K C; Wang, G; Liu, L

    2008-01-01

    In this work, we report that Zr 50 Cu 42 Al 8 bulk metallic glass (BMG) exhibits excellent glass forming ability and mechanical properties. Zr 50 Cu 42 Al 8 glassy rods with a diameter of 3 mm were prepared using conventional copper mould suction casting. The glassy rod exhibits a modulus of about 115 GPa and a fracture strength of about 2 GPa, and, as compared with other large-scale BMGs, it has excellent room-temperature plasticity of up to 20% under compression. The fracture mechanism of the rod was investigated by microstructural investigations, and it was found that the large plasticity of the as-cast rod is closely related to the in situ formation of nano-crystalline particles embedded in the amorphous matrix.

  14. Glasses, ceramics, and composites from lunar materials

    Science.gov (United States)

    Beall, George H.

    1992-01-01

    A variety of useful silicate materials can be synthesized from lunar rocks and soils. The simplest to manufacture are glasses and glass-ceramics. Glass fibers can be drawn from a variety of basaltic glasses. Glass articles formed from titania-rich basalts are capable of fine-grained internal crystallization, with resulting strength and abrasion resistance allowing their wide application in construction. Specialty glass-ceramics and fiber-reinforced composites would rely on chemical separation of magnesium silicates and aluminosilicates as well as oxides titania and alumina. Polycrystalline enstatite with induced lamellar twinning has high fracture toughness, while cordierite glass-ceramics combine excellent thermal shock resistance with high flexural strengths. If sapphire or rutile whiskers can be made, composites of even better mechanical properties are envisioned.

  15. Greek & Roman Mythology.

    Science.gov (United States)

    Bigelow, Alma

    Activities and background information on Greek and Roman mythology are presented. The unit is designed for eighth graders, but many of the activities can be modified for other grade levels. The unit includes: (1) a content outline; (2) a list of instructional materials including suggested textbooks, teacher-prepared materials, and resource…

  16. Mechanical Properties of Glass Surfaces Coated with Tin Oxide

    DEFF Research Database (Denmark)

    Swindlehurst, W. E.; Cantor, B.

    1978-01-01

    The effect of tin oxide coatings on the coefficient of friction and fracture strength of glass surfaces is studied. Experiments were performed partly on commercially treated glass bottles and partly on laboratory prepared microscope slides. Coatings were applied in the laboratory by decomposition...

  17. First roman pot tested by TOTEM

    CERN Multimedia

    2006-01-01

    TOTEM, one of the smaller experiments of the LHC, successfully tested its first 'roman pot' detectors on 3 November. A total of eight will be installed in the LHC near the CMS cavern. Marco Oriunno, project engineer of TOTEM (right), with Jean-Michel Lacroix from TS/MME (Mechanical and Materials Engineering) (left), standing behind one of the roman pot detectors. There is a small tribe in the land of CERN. Among its artefacts you may find colourfully painted rocks, a totem made of cardboard boxes, and a few roman pots. Known by the name of TOTEM, or 'TOTal, Elastic and diffractive cross-section Measurement' (not a tribe motto), they are a relatively small collaborative group in comparison to the main LHC experiments, with approximately 50 'tribe members'. Unlike the four larger experiments that will analyse new particles produced as a result of the collisions, TOTEM will investigate the ones that almost missed each other. When two beams of protons travelling in opposite di...

  18. Stress relaxation in tempered glass caused by heat soak testing

    DEFF Research Database (Denmark)

    Schneider, Jens; Hilcken, Jonas; Aronen, Antti

    2016-01-01

    Heat soak testing of tempered glass is a thermal process required after the tempering process itself to bring glasses of commercial soda-lime-silica-glass to failure that are contaminated with nickel sulphide inclusions, diameter 50 mm to 500 mm typically. Thus, the tests avoid a so-called "spont...... of commercial soda-lime-silica glass, it causes stress relaxation in tempered glass and the fracture pattern of the glass changes accordingly, especially thin glasses are affected. Based on the Tool-Narayanaswamy-Model, this paper comprises the theoretical background of the stress...

  19. A comparative study of progressive wear of four dental monolithic, veneered glass-ceramics.

    Science.gov (United States)

    Zhang, Zhenzhen; Yi, Yuanping; Wang, Xuesong; Guo, Jiawen; Li, Ding; He, Lin; Zhang, Shaofeng

    2017-10-01

    This study evaluated the wear performance and wear mechanisms of four dental glass-ceramics, based on the microstructure and mechanical properties in the progressive wear process. Bar (N = 40, n = 10) and disk (N = 32, n = 8) specimens were prepared from (A) lithium disilicate glass-ceramic (LD), (B) leucite reinforced glass-ceramic (LEU), (C) feldspathic glass-ceramic (FEL), and (D) fluorapatite glass-ceramic (FLU). The bar specimens were tested for three-point flexural strength, hardness, fracture toughness and elastic modulus. The disk specimens paired with steatite antagonists were tested in a pin-on-disk tribometer with 10N up to 1000,000 wear cycles. The wear analysis of glass-ceramics was performed using a 3D profilometer after every 200,000 wear cycles. Wear loss of steatite antagonists was calculated by measuring the weight and density using sensitive balance and Archimedes' method. Wear morphologies and microstructures were analyzed by scanning electron microscopy (SEM). The crystalline phase compositions were determined using X-ray diffraction (XRD). One-way analysis of variance (ANOVA) was used to analyze the data. Multiple pair-wise comparison of means was performed by Tukey's post-hoc test. LD showed the highest fracture toughness, flexural strength, elastic modulus and crystallinity, followed by LEU and FEL, and FLU showed the lowest. However, the hardness of LD was lower than all the other three types of ceramics. For steatite antagonists, LD produced the least wear loss of antagonist, followed by LEU and FEL, and FLU had the most wear loss. For glass-ceramic materials, LD exhibited similar wear loss as LEU, but more than FLU and FEL did. Moreover, fracture occurred on the wear surface of FLU. In the progressive wear process, veneering porcelains showed better wear resistance but fluorapatite veneering porcelains appeared fracture surface. Monolithic lithium disilicate glass-ceramics with higher mechanical properties showed more wear loss, however

  20. Bonding strength of glass-ceramic trabecular-like coatings to ceramic substrates for prosthetic applications.

    Science.gov (United States)

    Chen, Qiang; Baino, Francesco; Pugno, Nicola M; Vitale-Brovarone, Chiara

    2013-04-01

    A new approach based on the concepts of quantized fracture mechanics (QFM) is presented and discussed in this paper to estimate the bonding strength of trabecular-like coatings, i.e. glass-ceramic scaffolds mimicking the architecture of cancellous bone, to ceramic substrates. The innovative application of glass-derived scaffolds as trabecular-like coatings is proposed in order to enhance the osteointegration of prosthetic ceramic devices. The scaffolds, prepared by polymeric sponge replication, are joined to alumina substrates by a dense glass-ceramic coating (interlayer) and the so-obtained 3-layer constructs are investigated from micro-structural, morphological and mechanical viewpoints. In particular, the fracture strengths of three different crack propagation modes, i.e. glass-derived scaffold fracture, interface delamination or mixed fracture, are predicted in agreement with those of experimental mechanical tests. The approach proposed in this work could have interesting applications towards an ever more rational design of bone tissue engineering biomaterials and coatings, in view of the optimization of their mechanical properties for making them actually suitable for clinical applications. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Mineralogical textural and compositional data on the alteration of basaltic glass from Kilauea, Hawaii to 300 degrees C: Insights to the corrosion of a borosilicate glass waste-form

    International Nuclear Information System (INIS)

    Smith, D.K.

    1990-01-01

    Mineralogical, textural and compositional data accompanying greenschist facies metamorphism (to 300 degrees C) of basalts of the East Rift Zone (ERZ), Kilauea, Hawaii may be evaluated relative to published and experimental results for the surface corrosion of borosilicate glass. The ERZ alteration sequence is dominated by intermittent palagonite, interlayered smectite-chlorite, chlorite, and actinolite-epidote-anhydrite. Alteration is best developed in fractures and vesicles where surface reaction layers root on the glass matrix forming rinds in excess of 100 microns thick. Fractures control fluid circulation and the alteration sequence. Proximal to the glass surface, palagonite, Fe-Ti oxides and clays replace fresh glass as the surface reaction layer migrates inwards; away from the surface, amphibole, anhydrite, quartz and calcite crystallize from hydrothermal fluids in contact with the glass. The texture and composition of basaltic glass surfaces are similar to those of a SRL-165 glass leached statically for sixty days at 150 degrees C. While the ERZ reservoir is a complex open system, conservative comparisons between the alteration of ERZ and synthetic borosilicate glass are warranted. 31 refs., 2 figs

  2. Helium behaviour in nuclear glasses

    International Nuclear Information System (INIS)

    Fares, T.

    2011-01-01

    The present thesis focuses on the study of helium behavior in R7T7 nuclear waste glass. Helium is generated by the minor actinides alpha decays incorporated in the glass matrix. Therefore, four types of materials were used in this work. These are non radioactive R7T7 glasses saturated with helium under pressure, glasses implanted with 3 He + ions, glasses doped with curium and glasses irradiated in nuclear reactor. The study of helium solubility in saturated R7T7 glass has shown that helium atoms are inserted in the glass free volume. The results yielded a solubility of about 10 16 at. cm -3 atm. -1 . The incorporation limit of helium in this type of glass has been determined; its value amounted to about 2*10 21 at. cm -3 , corresponding to 2.5 at.%. Diffusion studies have shown that the helium migration is controlled by the single population dissolved in the glass free volume. An ideal diffusion model was used to simulate the helium release data which allowed to determine diffusion coefficients obeying to the following Arrhenius law: D = D 0 exp(-E a /kBT), where D 0 = 2.2*10 -2 and 5.4*10 -3 cm 2 s -1 and E a = 0.61 eV for the helium saturated and the curium doped glass respectively. These results reflect a thermally activated diffusion mechanism which seems to be not influenced by the glass radiation damage and helium concentrations studied in the present work (up to 8*10 19 at. g -1 , corresponding to 0.1 at.%). Characterizations of the macroscopic, structural and microstructural properties of glasses irradiated in nuclear reactor did not reveal any impact associated with the presence of helium at high concentrations. The observed modifications i.e. a swelling of 0.7 %, a decrease in hardness by 38 %, an increase between 8 and 34 % of the fracture toughness and a stabilization of the glass structure under irradiation, were attributed to the glass nuclear damage induced by the irradiation in reactor. Characterizations by SEM and TEM of R7T7 glasses implanted

  3. Mechanical properties of zirconia reinforced lithium silicate glass-ceramic.

    Science.gov (United States)

    Elsaka, Shaymaa E; Elnaghy, Amr M

    2016-07-01

    The aim of this study was to assess the mechanical properties of recently introduced zirconia reinforced lithium silicate glass-ceramic. Two types of CAD/CAM glass-ceramics (Vita Suprinity (VS); zirconia reinforced lithium silicate and IPS e.max CAD (IC); lithium disilicate) were used. Fracture toughness, flexural strength, elastic modulus, hardness, brittleness index, and microstructures were evaluated. Data were analyzed using independent t tests. Weibull analysis of flexural strength data was also performed. VS had significantly higher fracture toughness (2.31±0.17MPam(0.5)), flexural strength (443.63±38.90MPa), elastic modulus (70.44±1.97GPa), and hardness (6.53±0.49GPa) than IC (Pglass-ceramic revealed significantly a higher brittleness index (2.84±0.26μm(-1/2)) (lower machinability) than IC glass-ceramic (Pglass-ceramic revealed a lower probability of failure and a higher strength than IC glass-ceramic according to Weibull analysis. The VS zirconia reinforced lithium silicate glass-ceramic revealed higher mechanical properties compared with IC lithium disilicate glass-ceramic. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  4. Doctors in ancient Greek and Roman rhetorical education.

    Science.gov (United States)

    Gibson, Craig A

    2013-10-01

    This article collects and examines all references to doctors in rhetorical exercises used in ancient Greek and Roman schools in the Roman Empire. While doctors are sometimes portrayed positively as philanthropic, expert practitioners of their divinely sanctioned art, they are more often depicted as facing charges for poisoning their patients.

  5. Medieval and early modern approaches to fractures of the proximal humerus: an historical review

    DEFF Research Database (Denmark)

    Brorson, S.

    2010-01-01

    The diagnosis and management of complex fractures of the proximal humerus have challenged surgical practitioners and medical writers since the earliest recorded surgical texts. Current knowledge of fractures of the proximal humerus has been obtained through pathoanatomical and biomechanical studies...... within the last two centuries. However, the historical preconditions for this development have not been studied. This paper reviews written sources from the fall of the Roman Empire to the late eighteenth century. Medieval and early modern writers mainly rely on the Hippocratic writings De Fracturis...

  6. Characterization of the Roman curse tablet

    Science.gov (United States)

    Liu, Wen; Zhang, Boyang; Fu, Lin

    2017-08-01

    The Roman curse tablet, produced in ancient Rome period, is a metal plate that inscribed with curses. In this research, several techniques were used to find out the physical structure and chemical composition of the Roman curse tablet, and testified the hypothesis that whether the tablet is made of pure lead or lead alloy. A sample of Roman Curse Tablet from the Johns Hopkins Archaeological Museum was analyzed using several different characterization techniques to determine the physical structure and chemical composition. The characterization techniques used were including optical microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and differential scanning calorimetry (DSC). Because of the small sample size, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and X-ray fluorescence (XRF) cannot test the sample. Results from optical microscopy and SEM, enlarged images of the sample surface were studied. The result revealed that the sample surface has a rough, non-uniform, and grainy surface. AFM provides three-dimensional topography of the sample surface, studying the sample surface in atomic level. DSC studies the thermal property, which is most likely a lead-alloy, not a pure lead. However, none of these tests indicated anything about the chemical composition. Future work will be required due to the lack of measures finding out its chemical composition. Therefore, from these characterization techniques above, the Roman curse tablet sample is consisted of lead alloy, not pure lead.

  7. Divorce by consent in Roman law and contemporary law

    OpenAIRE

    Ignjatović Marija; Kitanović Tanja

    2013-01-01

    The subject matter of this paper is divorce by mutual consent in Roman law and contemporary law. In the first part of this article, the authors analyzes the key tenets of consensual divorce in Roman law, with specific reference to the impact of Christian religious teaching on the concepts of marriage and divorce as well as on the Roman rulers' constitutions, which marked the beginning of the process of restricting the right to divorce. In the central part of the paper, the authors examines th...

  8. Fracture mode during cyclic loading of implant-supported single-tooth restorations

    DEFF Research Database (Denmark)

    Hosseini, Mandana; Kleven, Erik; Gotfredsen, Klaus

    2012-01-01

    restorations of zirconia abutment-retained crowns with zirconia copings veneered with glass-ceramics (n=8) and feldspathic ceramics (n=8). The control group was composed of 16 metal ceramic restorations of titanium abutment-retained crowns with gold alloy copings veneered with glass (n=8) and feldspathic...... ceramics (n=8). The palatal surfaces of the crowns were exposed to cyclic loading of 800 N with a frequency of 2 Hz, which continued to 4.2 million cycles or until fracture of the copings, abutments, or implants. The number of cycles and the fracture modes were recorded. The fracture modes were analyzed...

  9. Fracture mechanics parameters for glasses: A compilation and correlation

    International Nuclear Information System (INIS)

    Freiman, S.W.; Baker, T.L.; Wachtmann, J.B.

    1985-01-01

    This paper describes a computerized fracture mechanics data base and associated computer programs which permit extension and modification of data base as well as selection, plotting and curve fitting. Some preliminary results of correlations of fracture energy, gamma, with composition and elastic modulus are presented

  10. Mechanical Properties of Man-Made Mineral glass fibres

    DEFF Research Database (Denmark)

    Lund, Majbritt Deichgræber; Yue, Yuanzheng

    of man made mineral wool fibres, and an improvement of the mechanical performances of man made mineral wool fibres are an evitable task for us. To do so, it is important to look into the fracture behaviour and its connection to the mechanical strength. In order to improve the understanding...... of the information gained from the mechanical tests, fracture characteristics of individual glass fibres are imaged by scanning electron microscopy. The fracture surfaces showed to fall in three groups; 1) surfaces including fracture mirror, mist and hackle, 2) bend fracture surfaces and 3) surfaces including pores...

  11. "Roman Pot" at the ISR

    CERN Multimedia

    CERN PhotoLab

    1980-01-01

    "Roman pots" are stainless steel containers, which can be moved from outside the vacuum chamber towards the beam. They house detectors which are conveniently at atmospheric pressure and can still be brought close to the limit of the circulating beam, to detect particles emanating at very small angles from the intersection of two colliding beams. Eifionydd Jones was the inventor of this device, highly successful at the ISR and now used again at the TOTEM experiment at the LHC. This particular Roman Pot, with a thickness of 0.2 mm, was built in 1980 for experiment R210 in intersection I-2, in preparation for proton-antiproton collisions in 1981. See also 7501065.

  12. A damage-tolerant glass.

    Science.gov (United States)

    Demetriou, Marios D; Launey, Maximilien E; Garrett, Glenn; Schramm, Joseph P; Hofmann, Douglas C; Johnson, William L; Ritchie, Robert O

    2011-02-01

    Owing to a lack of microstructure, glassy materials are inherently strong but brittle, and often demonstrate extreme sensitivity to flaws. Accordingly, their macroscopic failure is often not initiated by plastic yielding, and almost always terminated by brittle fracture. Unlike conventional brittle glasses, metallic glasses are generally capable of limited plastic yielding by shear-band sliding in the presence of a flaw, and thus exhibit toughness-strength relationships that lie between those of brittle ceramics and marginally tough metals. Here, a bulk glassy palladium alloy is introduced, demonstrating an unusual capacity for shielding an opening crack accommodated by an extensive shear-band sliding process, which promotes a fracture toughness comparable to those of the toughest materials known. This result demonstrates that the combination of toughness and strength (that is, damage tolerance) accessible to amorphous materials extends beyond the benchmark ranges established by the toughest and strongest materials known, thereby pushing the envelope of damage tolerance accessible to a structural metal.

  13. Abrasive wear behaviour of bio-active glass ceramics containing ...

    Indian Academy of Sciences (India)

    In this study, abrasive wear behaviour of bio-active glass ceramic materials produced with two different processes is studied. Hot pressing process and conventional casting and controlled crystallization process were used to produce bio-active ceramics. Fracture toughness of studied material was calculated by fracture ...

  14. Tuning glass formation and brittle behaviors by similar solvent element substitution in (Mn,Fe)-based bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tao [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Li, Ran, E-mail: liran@buaa.edu.cn [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Xiao, Ruijuan [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Liu, Gang [State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Wang, Jianfeng [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China); Zhang, Tao, E-mail: zhangtao@buaa.edu.cn [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)

    2015-02-25

    A family of Mn-rich bulk metallic glasses (BMGs) was developed through the similar solvent elements (SSE) substitution of Mn for Fe in (Mn{sub x}Fe{sub 80−x})P{sub 10}B{sub 7}C{sub 3} alloys. The effect of the SSE substitution on glass formation, thermal stability, elastic constants, mechanical properties, fracture morphologies, Weibull modulus and indentation fracture toughness was discussed. A thermodynamics analysis provided by Battezzati et al. (L. Battezzati, E. Garrone, Z. Metallkd. 75 (1984) 305–310) was adopted to explain the compositional dependence of the glass-forming ability (GFA). The elastic moduli follow roughly linear correlations with the substitution concentration of Mn in (Mn{sub x}Fe{sub 80−x})P{sub 10}B{sub 7}C{sub 3} BMGs. The introduction of Mn to replace Fe significantly decreases the plasticity of the resulting BMGs and the Weibull modulus of the fracture strength. A super-brittle Mn-based BMGs of (Mn{sub 55}Fe{sub 25})P{sub 10}B{sub 7}C{sub 3} BMGs were found with the indentation fracture toughness (K{sub c}) of 1.91±0.04 MPa m{sup 1/2}, the lowest value among all kinds of BMGs so far. The atomic and electronic structure of the selected BMGs were simulated by the first principles molecular dynamics calculations based on density functional theory, which provided a possible understanding of the brittleness caused by the similar chemical element replacement of Mn for Fe.

  15. Mechanical properties of very thin cover slip glass disk

    Indian Academy of Sciences (India)

    Unknown

    Mechanical properties of very thin cover slip glass disk. A SEAL, A K DALUI, M BANERJEE, A K MUKHOPADHYAY* and K K PHANI. Central Glass and Ceramic Research Institute, Kolkata 700 032, India. Abstract. The biaxial flexural strength, Young's modulus, Vicker's microhardness and fracture toughness data for very ...

  16. Putting Roman Dams in Context: a Virtual Approach

    Science.gov (United States)

    Decker, M. J.; Du Vernay, J. P.; Mcleod, J. B.

    2017-08-01

    Water resources and management have become a critical global issue. During the half-millennium of its existence, the Roman Empire developed numerous strategies to cope with water management, from large-scale urban aqueduct systems, to industrial-scale water mills designed to cope with feeding growing city populations. Roman engineers encountered, adopted, and adapted indigenous hydraulic systems, and left lasting imprints on the landscape of the Mediterranean and temperate Western Europe by employing a range of water technologies. A recent academic study has enabled the identification of remains of and references to seventy-two dams from the Roman era, constructed in Spain between the 1st and 4th century AD. Such unique heritage, without comparisons in the Mediterranean makes Spain an emblematic case study for the analysis of Roman hydraulic engineering and water management policies. Fifty dams have been located and detailed. The twenty-two outstanding, although identified on the ground, have not been able to be acceptably characterized, due in some cases to their being ruins in a highly degraded state, others due to their being masked by repairs and reconstructions subsequent to the Roman era. A good example of such neglected dams is the buttress dam of Consuegra , in Toledo province (Castilla-La Mancha). Dating to the 3rd - 4th century AD, the Dam of Consuegra, on the basin of the Guadiana, with its over 600 metres length and 4,80 metres height, is a remarkable case of Roman engineering mastery. It had a retaining wall upstream, numerous buttresses and perhaps an embankment downstream, of which no remains are left. The application of 3D digital imaging technique to create a high quality virtual model of such monuments has proved to be successful especially for the study of the technological aspects related its construction. The case study of the Roman dam of Muel (Zaragoza) has shown, in fact, as best practices in digital archaeology can provide an original and

  17. Roman Engineering, Public Works and Importance of Public Objects in Roman Law

    Directory of Open Access Journals (Sweden)

    Vanessa Ponte-Arrebola

    2017-01-01

    Full Text Available The skill and ability of the Romans in civil engineering and public works largely contributed to the establishment and success of their civilization. Many of the constructed works were built for the possibility of public use and enjoyment by its citizens, known as res publicae in usu publico.

  18. Josephus' Antiquities 1-11 and Greco-Roman Historiography

    DEFF Research Database (Denmark)

    Friis, Martin

    The dissertation Josephus’ Antiquities 1-11 and Greco-Roman historiography provides an extensive study in five chapters of the various ways in which Josephus presents himself as an historian in the first eleven books of the Antiquities. From this analysis, it emerges that his manner of self......-portrayal is closely comparable with that of a number of Greco-Roman historians....

  19. Woman in Roman law: Subject or object of the law?

    Directory of Open Access Journals (Sweden)

    Bogunović Mirjana

    2012-01-01

    Full Text Available In Rome, legal status of woman and her factual possibilities of impact on public life were in serious discrepancy. General attitude of the legal status of woman in time of Romans is best shown by Papinian, 'In many provisions of our law, the position of woman is worse than of man (D.9.1.5.'. Every free Roman woman was considered a subject of law, according to classical Roman law. Nevertheless, there were extensive legislations that limited her legal and business capacity. Naturally, woman did not have legal personality in all periods of Roman state and her legal status was adjusted to the factual changes that had occurred in Roman society. What makes her position specific in Rome is progressive social role that did not exist in Greek-Asian world. From these previously mentioned views, which were confronting, it is possible to draw some doubts. Was woman really on the margins of political happenings, or was she an actual actor, even initiator, of some political events?.

  20. Astronomy in towns? An archaeoastronomical approach to the Roman urbanism

    Science.gov (United States)

    Rodríguez-Antón, A.; Belmonte, J. A.; González-García, A. C.

    2017-03-01

    Although the final definition of Archaeoastronomy is still under debate, what is clear is that this discipline offers a different approach to the knowledge of ancient cultures than traditional archaeology has done so far. Archaeoastronomy considers the sky as an inseparabe part of the environment and thus an element of the transformed landscape with highly symbolic content. In the case of the Roman culture, the great colonizing activity involved continuous spatial transformations and the skyscape should be considered as a piece of the created urbanized spaces. For this reason, a number of fieldwork campaigns were conducted in several Roman cities across different regions of the ancient Roman Empire in order to study the configuration of those landscapes and the possible integration of the sky during the buiding processes. At the present, our group has the largest sample of orientations of Roman settlements so far, and here it is shown the preliminary results of an statistical analysis which may offer new answers to the various still open questions in Roman urbanism, often faced from conservative views.

  1. Divorce by consent in Roman law and contemporary law

    Directory of Open Access Journals (Sweden)

    Ignjatović Marija

    2013-01-01

    Full Text Available The subject matter of this paper is divorce by mutual consent in Roman law and contemporary law. In the first part of this article, the authors analyzes the key tenets of consensual divorce in Roman law, with specific reference to the impact of Christian religious teaching on the concepts of marriage and divorce as well as on the Roman rulers' constitutions, which marked the beginning of the process of restricting the right to divorce. In the central part of the paper, the authors examines the regulation on the consensual divorce in some contemporary legal systems. In addition, the authors provides a substantial analysis of the normative framework on the termination of marriage in the positive Serbian legislation. In the final part of the paper, the authors provides a comparative analysis and underscores the observed similarities and differenced in the regulation of the institute of consensual divorce in Roman law and in the contemporary legislation.

  2. The ecclesiastical situation of the first generation Roman Christians

    Directory of Open Access Journals (Sweden)

    A. B. du Toit

    1997-12-01

    Full Text Available Forming pan of a trilogy about the first generation Roman Christians, this anicle concentrates on the ecclesiastical aspect. From some scattered and relatively small groups, the numbers of Roman Christians increased markedly in the second half of the first century. According to Romans 16, Jewish Christians played a significant role in the initial period, although Gentile Christians were in the majority. Friction between these groups may have been a problem, but was not Paul's main concern. The Gentile Christians were mainly from a foreign background. Thus the first Christian community had a strongly cosmopolitan character. The plurality of house-churches was mainly due to practical factors, but social differentiation might have played a role. Meetings most probably took place in the ordinary rented apanments of insulae. Romans 16 renders a vivid picture of the leadership activities of Christian women and of Paul's enlightened position in this regard.

  3. The Gate of Heaven: Revisiting Roman Mithraic Cosmology

    Science.gov (United States)

    Assasi, R.

    2016-01-01

    The definition and origins of Roman Mithraism remain highly problematic and controversial among modern scholars. The majority of research on Roman Mithraism focuses on interpreting the physical evidence because no considerable written narratives or theology from the religion survive. The most important Mithraic artifact is a repeated bull-slaying scene, which leaves no doubt that this figure conveys the core divine message of the cult. There is also another important Mithraic character that seems to be as important as the bull-slayer. This figure is a lion-headed man entwined by a snake. The author suggests that these figures represent the north ecliptic pole and argues for the importance of this astronomical reference in the Mithraic iconography and mythology. The author also demonstrates the possible relation of his proposed astrological model to the geocentric understanding of the axial precession around the ecliptic pole, where the Roman bull-slaying Mithras could be visualized in the form of a Mithraic constellation. This astrological model also is proposed to be the architectural design concept of Roman Mithraeum. The author also points to the core Christian symbols as possible contemporaneous parallels or derivatives of the Mithraic iconography and theology.

  4. Influence of different catilever extensions and glass or polyamaramid reinforcement fibers on fracture strength of implant-supported temporary

    Directory of Open Access Journals (Sweden)

    Paola Colán Guzmán

    2008-04-01

    Full Text Available In long-term oral rehabilitation treatments, resistance of provisional crowns is a very important factor, especially in cases of an extensive edentulous distal space. The aim of this laboratorial study was to evaluate an acrylic resin cantilever-type prosthesis regarding the flexural strength of its in-balance portion as a function of its extension variation and reinforcement by two types of fibers (glass and polyaramid, considering that literature is not conclusive on this subject. Each specimen was composed by 3 total crowns at its mesial portion, each one attached to an implant component (abutment, while the distal portion (cantilever had two crowns. Each specimen was constructed by injecting acrylic resin into a two-part silicone matrix placed on a metallic base. In each specimen, the crowns were fabricated with either acrylic resin (control group or acrylic resin reinforced by glass (Fibrante, Angelus or polyaramide (Kevlar 49, Du Pont fibers. Compression load was applied on the cantilever, in a point located 7, 14 or 21 mm from the distal surface of the nearest crown with abutment, to simulate different extensions. The specimen was fixed on the metallic base and the force was applied until fracture in a universal test machine. Each one of the 9 sub-groups was composed by 10 specimens. Flexural strength means (in kgf for the distances of 7, 14 and 21 mm were, respectively, 28.07, 8.27 and 6.39 for control group, 31.89, 9.18 and 5.16 for Kevlar 49 and 30.90, 9.31 and 6.86 for Fibrante. Data analysis ANOVA showed statistically significant difference (p<0.05 only regarding cantilever extension. Tukey's test detected significantly higher flexural strength for the 7 mm-distance, followed by 14 and 21 mm. Fracture was complete only on specimens of non-reinforced groups.

  5. Flexural Progressive Failure of Carbon/Glass Interlayer and Intralayer Hybrid Composites.

    Science.gov (United States)

    Wang, Qingtao; Wu, Weili; Gong, Zhili; Li, Wei

    2018-04-17

    The flexural progressive failure modes of carbon fiber and glass fiber (C/G) interlayer and intralayer hybrid composites were investigated in this work. Results showed that the bending failure modes for interlayer hybrid composites are determined by the layup structure. Besides, the bending failure is characterized by the compression failure of the upper layer, when carbon fiber tends to distribute in the upper layer, the interlayer hybrid composite fails early, the failure force is characterized by a multi-stage slightly fluctuating decline and the fracture area exhibits a diamond shape. While carbon fiber distributes in the middle or bottom layer, the failure time starts late, and the failure process exhibits one stage sharp force/stress drop, the fracture zone of glass fiber above the carbon layers presents an inverted trapezoid shape, while the fracture of glass fiber below the carbon layers exhibits an inverted triangular shape. With regards to the intralayer hybrid composites, the C/G hybrid ratio plays a dominating role in the bending failure which could be considered as the mixed failures of four structures. The bending failure of intralayer hybrid composites occurs in advance since carbon fiber are located in each layer; the failure process shows a multi-stage fluctuating decline, and the decline slows down as carbon fiber content increases, and the fracture sound release has the characteristics of a low intensity and high frequency for a long time. By contrast, as glass fiber content increases, the bending failure of intralayer composites is featured with a multi-stage cliff decline with a high amplitude and low frequency for a short-time fracture sound release.

  6. Fracture strengths of chair‑side‑generated veneers cemented with ...

    African Journals Online (AJOL)

    Introduction: CAD/CAM (computer‑aided design and computer‑aided manufacturing) systems have refreshed the idea of chair‑side production of restorations, but the fracture of ceramic veneers remains a problem. Cementation with glass fibers may improve the fracture strengths and affect the failure modes of ...

  7. Der Dichter Roman Svendborg

    DEFF Research Database (Denmark)

    Schweppenhäuser, Jakob

    2016-01-01

    Roman Svendborg? Mein Großvater, Hermann Schweppenhäuser, schenkte mir vor einigen Jahren einmal einen Gedichtband, dessen Verfasser mir bis lang noch nicht bekannt war. Damals noch ein junger dänischer Student der Skandinavistik waren mir schließlich nicht alle deutschsprachigen Dichter geläufig...

  8. The term origo in Roman epigraphy

    Directory of Open Access Journals (Sweden)

    Rafael GONZÁLEZ FERNÁNDEZ

    2012-03-01

    Full Text Available It is sometimes very difficult to interpret the term origo, since it can refer to different elements such as birth, place of origin, family or tribe. From the Republican period the Romans used to include this type of information in their inscriptions after the mention of the name, although, curiously, they did not employ the term origo itself, but other forms of expression. In this work we suggest that in Roman epigraphy this term was used, from the end of the Second Century and during the first half of the Third Century A. D., mainly in the times of the Severan Dynasty.

  9. Expected behavior of HLW glass in storage

    International Nuclear Information System (INIS)

    McElroy, J.L.

    1975-01-01

    Glass produced by solidification of high-level radioactive liquid waste is studied. Conditions to which the waste form will be exposed in a typical handling sequence representative of current U. S. planning are tabulated. The reference matrix for waste form characterization is discussed, and some of the properties of high-level waste glass are described: physical properties, leachability, fracturing, vaporization, and containment in canister. 12 fig, 5 tables

  10. Development of abrasion resistant glass-ceramics from industrial waste products. Final report

    Energy Technology Data Exchange (ETDEWEB)

    von Roode, M.

    1983-05-26

    Slag-ceramics were produced from glass compositions using pelletized slag as the major ingredient. The abrasion resistance, fracture toughness and microstructure of the prepared glass and glass-ceramics were evaluated. Glas-ceramics with good abrasion resistance were obtained when iron oxide in conjunction with carbon was used as a nucleating agent. 5 figs., 11 tabs.

  11. Design and Fabrication of Automatic Glass Cutting Machine

    Science.gov (United States)

    Veena, T. R.; Kadadevaramath, R. S.; Nagaraj, P. M.; Madhusudhan, S. V.

    2016-09-01

    This paper deals with the design and fabrication of the automatic glass or mirror cutting machine. In order to increase the accuracy of cut and production rate; and decrease the production time and accidents caused due to manual cutting of mirror or glass, this project aims at development of an automatic machine which uses a programmable logic controller (PLC) for controlling the movement of the conveyer and also to control the pneumatic circuit. In this machine, the work of the operator is to load and unload the mirror. The cutter used in this machine is carbide wheel with its cutting edge ground to a V-shaped profile. The PLC controls the pneumatic cylinder and intern actuates the cutter along the glass, a fracture layer is formed causing a mark to be formed below the fracture layer and a crack to be formed below the rib mark. The machine elements are designed using CATIA V5R20 and pneumatic circuit are designed using FESTO FLUID SIM software.

  12. Effects of solar radiation on glass

    Science.gov (United States)

    Tucker, Dennis S.; Kinser, Donald L.

    1991-01-01

    The effects of solar radiation of selected glasses are reported. Optical property degradation is studied using UV-Vis spectrophotometry. Strength changes are measured using a concentric ring bend test. Direct fracture toughness measurements using an indentation test are planned.

  13. Creating a provincial landscape: roman imperialism and rural change in Lusitania

    Directory of Open Access Journals (Sweden)

    J. C Edmondson

    2010-02-01

    Full Text Available SUMMARY: This paper suggests some general approaches and raises some problems in studying the impact of Rome on the rural landscape in Lusitania. It concentrates on three crucial ways in which the landscape was transformed under Roman rule: (a changes in the pattern of rural settlement; (b changes in the nature of land use and agrarian exploitation; and (c changes in the ways in which the inhabitants of Lusitania perceived and thought about their world. It argues that a synthesis is needed of archaeological evidence from across the province, so that the impact of Rome on rural settlemet patterns may be compared in differing environmental regions. Further intensive field survey should also help to resolve some current problems in reconstructing the pattern of Iron Age and Roman rural settlement. Increased collection and analysis of pollen samples, carbonised wood, seeds, agricultural implements and animal bones is needed to assess more precisely the extent to which the Romans caused major changes in the nature of land use and agrarian exploitation. When accounting for change, it is essential to consider a wide variety of factors and to remember that rural change continued to occur throughout the Roman period. Finally, it was in forcing the inhabitants of Lusitania to perceive their world in radically new ways that the Romans made a lasting impact on the provincial landscape. First, the Romans created broad ethnic identities for their opponents, ignoring the complex, highly fragmented ethnic and regional geography of the area. Then by dividing the region into clearly defined civitates, they forced the inhabitants of Lusitania to envisage the landscape in a very different manner than before. Finally, a series of rituals emphasising Roman power (the census, the holding of judicial assizes, and the activities of the provincial council regularly reinforced these radically new mental maps of the new Roman provincial landscape.

  14. Manufacture, characterisation and properties of novel fluorcanasite glass-ceramics.

    Science.gov (United States)

    Pollington, Sarah; van Noort, Richard

    2012-11-01

    The aim of this study was to investigate the manufacture and characterisation of different compositions of fluorcanasite glass-ceramics with reduced fluorine content and to assess their mechanical and physical properties. Three compositional variations (S80, S81 and S82) of a fluorcanasite glass were investigated. Differential thermal analysis (DTA) and X-ray diffraction (XRD) identified crystallisation temperatures and phases. X-ray fluorescence (XRF) determined the element composition in the glass-ceramics. Different heat treatments [2 h nucleation and either 2 or 4 h crystallisation] were used for the glasses. Scanning electron microscopy (SEM) examined the microstructure of the cerammed glass. The chemical solubility, biaxial flexural strength, fracture toughness, hardness and brittleness index of S81 and S82 fluorcanasite were investigated with lithium disilicate (e.max CAD, Ivoclar Vivadent) as a commercial comparison. Statistical analysis was performed using one-way ANOVA with Tukey's multiple comparison tests (Pglasses. XRD analysis confirmed fluorcanasite formation with the S81 and S82 compositions, with the S82 (2+2h) showing the most prominent crystal structure. The chemical solubility of the glass-ceramics was significantly different, varying from 2565 ± 507 μg/cm(2) for the S81 (2+2 h) to 722 ± 177 μg/cm(2) for the S82 (2+2 h) to 37.4 ± 25.2 μg/cm(2) for the lithium disilicate. BFS values were highest for the S82 (2+2 h) composition (250 ± 26 MPa) and lithium disilicate (266 ± 37 MPa) glass-ceramics. The fracture toughness was higher for the S82 compositions, with the S82 (2+2h) attaining the highest value of 4.2 ± 0.3 MPa m(1/2)(P=0.01). The S82 (2+2 h) fluorcanasite glass-ceramic had the lowest brittleness index. The S82 (2+2 h) fluorcanasite glass-ceramic has acceptable chemical solubility, high biaxial flexural strength, fracture toughness and hardness. A novel glass-ceramic has been developed with potential as a restorative material. The

  15. Contextualizing the sacred in the Hellenistic and Roman Near East

    DEFF Research Database (Denmark)

    The study of religion and religious identities in the Hellenistic and Roman Near East has been a focus within archaeology and ancient history for centuries. Yet the transition between the Hellenistic and Roman period remains difficult to grasp from the archaeological and epigraphic evidence....... This volume brings together contributions by leading scholars working on religious identity and religion in the Hellenistic and Roman periods in the Roman Near East. For this volume they have been asked to address a variety of questions concerning religion, religious development, and religious identities from...... literary tradition, but when seen through the lens of contextualization, the material and textual evidence brings forward new narratives about the great variations in worship, myths, and identities, as well as the different religious systems of the region and of the people inhabiting it. The contributions...

  16. The TLRR II – Providing Digital Infrastructure to Research Roman Republican Trials

    Directory of Open Access Journals (Sweden)

    Kirsten Jahn

    2016-12-01

    Full Text Available The project Trials in the Late Roman Republic II (TLRR II aims at collecting, organizing, and analyzing information about Roman legal cases in an XML database. M. Alexander published the book “Trials in the Late Roman Republic, 149 BC to 50 BC” (TLRR I in 1990, and initiated the current project that will make Roman republican trials easily accessible with modern technology. For each case a short description is provided, a clear distinction between assumptions and facts is made, and an updated bibliography can be found at the end of each entry. The open access database can serve both as a reference work and as a starting point for further research in Roman Republican history. It could be a connecting link within the developing digital infrastructure for that era.

  17. Compositional and microstructural design of highly bioactive P2O5-Na2O-CaO-SiO2 glass-ceramics.

    Science.gov (United States)

    Peitl, Oscar; Zanotto, Edgar D; Serbena, Francisco C; Hench, Larry L

    2012-01-01

    Bioactive glasses having chemical compositions between 1Na(2)O-2CaO-3SiO(2) (1N2C3S) and 1.5Na(2)O-1.5CaO-3SiO(2) (1N1C2S) containing 0, 4 and 6 wt.% P(2)O(5) were crystallized through two stage thermal treatments. By carefully controlling these treatments we separately studied the effects on the mechanical properties of two important microstructural features not studied before, crystallized volume fraction and crystal size. Fracture strength, elastic modulus and indentation fracture toughness were measured as a function of crystallized volume fraction for a constant crystal size. Glass-ceramics with a crystalline volume fraction between 34% and 60% exhibited a three-fold improvement in fracture strength and an increase of 40% in indentation fracture toughness compared with the parent glass. For the optimal crystalline concentration (34% and 60%) these mechanical properties were then measured for different grain sizes, from 5 to 21 μm. The glass-ceramic with the highest fracture strength and indentation fracture toughness was that with 34% crystallized volume fracture and 13 μm crystals. Compared with the parent glass, the average fracture strength of this glass-ceramic was increased from 80 to 210 MPa, and the fracture toughness from 0.60 to 0.95 MPa.m(1/2). The increase in indentation fracture toughness was analyzed using different theoretical models, which demonstrated that it is due to crack deflection. Fortunately, the elastic modulus E increased only slightly; from 60 to 70 GPa (the elastic modulus of biomaterials should be as close as possible to that of cortical bone). In summary, the flexural strength of our best material (215 MPa) is significantly greater than that of cortical bone and comparable with that of apatite-wollastonite (A/W) bioglass ceramics, with the advantage that it shows a much lower elastic modulus. These results thus provide a relevant guide for the design of bioactive glass-ceramics with improved microstructure. Copyright © 2011 Acta

  18. Roman Toi kaks suurt armastust : muusika ja Eesti / Elle Puusaag ; foto: V. Sarapuu

    Index Scriptorium Estoniae

    Puusaag, Elle, 1945-2017

    2007-01-01

    Toronto Eesti Maja kristallsaalis toimunud pidulikust õhtust 5. detsembril: maestro Roman Toi mälestusteraamatu esitlusest. Rets. rmt.: Toi, Roman. Kaunimad laulud pühendan sull' : Roman Toi mälestused/toimetaja Tiina Sarv. Toronto : Viljandi : T. Sarv, 2007

  19. Crystallization and properties of a spodumene-willemite glass ceramic

    International Nuclear Information System (INIS)

    Hu, A.M.; Li, M.; Dali, D.L. Mao; Liang, K.M.

    2005-01-01

    Spodumene-willemite glass ceramics were produced by replacement of Al 2 O 3 in lithium aluminium silicate by ZnO. With replacement of Al 2 O 3 by ZnO, the batch melting temperature, glass transition temperature (T g ) and crystallization temperature (T p ) all decreased. The main crystalline phases precipitated were eucriptite, β-spodumene and willemite (Zn 2 SiO 4 ). All compositions of glass ceramics showed bulk crystallization. As ZnO content increased, the grain sizes and thermal expansion coefficients increased, while the flexural strength and fracture toughness of the glass-ceramics increased first, and then decreased. The mechanical properties were correlated with crystallization and morphology of glass ceramics

  20. Greek and Roman Myths.

    Science.gov (United States)

    Carr, Fredella; Faggionato, Michael

    Designed for use with the text "Greek and Roman Myths," this junior high school learning activity packet introduces students to mythology and examines the influence of myths on contemporary culture. Over 20 exercises, tagged to specific readings in the text, cover identification of the major gods, the Prometheus myth, the Atlas myth,…

  1. Proof test diagrams for Zerodur glass-ceramic

    Science.gov (United States)

    Tucker, D. S.

    1991-01-01

    Proof test diagrams for Zerodur glass-ceramics are calculated from available fracture mechanics data. It is shown that the environment has a large effect on minimum time-to-failure as predicted by proof test diagrams.

  2. Zirconia toughened mica glass ceramics for dental restorations.

    Science.gov (United States)

    Gali, Sivaranjani; K, Ravikumar; Murthy, B V S; Basu, Bikramjit

    2018-03-01

    The objective of the present study is to understand the role of yttria stabilized zirconia (YSZ) in achieving the desired spectrum of clinically relevant mechanical properties (hardness, elastic modulus, fracture toughness and brittleness index) and chemical solubility of mica glass ceramics. The glass-zirconia mixtures with varying amounts of YSZ (0, 5, 10, 15 and 20wt.%) were ball milled, compacted and sintered to obtain pellets of glass ceramic-YSZ composites. Phase analysis was carried out using X-ray diffraction and microstructural characterization with SEM revealed the crystal morphology of the composites. Mechanical properties such as Vickers hardness, elastic modulus, indentation fracture toughness and chemical solubility were assessed. Phase analysis of sintered pellets of glass ceramic-YSZ composites revealed the characteristic peaks of fluorophlogopite (FPP) and tetragonal zirconia. Microstructural investigation showed plate and lath-like interlocking mica crystals with embedded zirconia. Vickers hardness of 9.2GPa, elastic modulus of 125GPa, indentation toughness of 3.6MPa·m 1/2 , and chemical solubility of 30μg/cm 2 (well below the permissible limit) were recorded with mica glass ceramics containing 20wt.% YSZ. An increase in hardness and toughness of the glass ceramic-YSZ composites with no compromise on their brittleness index and chemical solubility has been observed. Such spectrum of properties can be utilised for developing a machinable ceramic for low stress bearing inlays, onlays and veneers. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  3. Using Roman Sites: A Teacher's Guide. Education on Site.

    Science.gov (United States)

    Watson, Iain

    This book is about finding the evidence to help pupils discover the Romans, especially in Britain. The Romans changed the culture and landscape of Britain and left a wide range of evidence to be investigated today. Pupils need to be presented this range of evidence and the interpretations put on them. The evidence presented is both archaeological…

  4. Evaluation of material fracture energy by its heat content

    International Nuclear Information System (INIS)

    Frolov, G.A.; Pasichnyj, V.V.; Polezhaev, Yu.V.; Frolov, A.A.; Choba, A.V.

    1986-01-01

    Based on published and experimental data it is shown that there is a simple relationship between the heat of evaporation and heat content. This allows in some instances the evaluation of a rate of material fracture by its content. Experimental and theoretical data for quartz glass ceramics, and glass-reinforced plastic are presented

  5. Mechanical properties of a co-extruded Metallic Glass/Alloy (MeGA) rod-Effect of the metallic glass volume fraction

    International Nuclear Information System (INIS)

    Gravier, S.; Blandin, J.J.; Suery, M.

    2010-01-01

    A Metallic Glass/Alloy (MeGA) rod with a core in zirconium-based bulk metallic glass and a sleeve in aluminium alloy has been successfully elaborated by co-extrusion. SEM observations of the cross-section of the rod show that the interface between the glass and the alloy is defect-free. Compression tests are carried out at room temperature on the MeGA rods containing various glass volume fractions. The yield stress is well described by the rule of mixtures which combines the strength of the glass and that of the alloy, suggesting isostrain behaviour as could be expected. During compression, a good mechanical bonding is observed in the MeGA-rod even after the first fracture of the metallic glass. Finally, push-out tests are performed to evaluate the bonding quality between the two materials. Large values of the shear strength are measured which confirms that co-extrusion leads to good bonding between the glass and the aluminium alloy.

  6. Study of archaeological analogs for the validation of nuclear glass long-term behavior models

    International Nuclear Information System (INIS)

    Verney-Carron, A.

    2008-10-01

    Fractured archaeological glass blocks collected from a shipwreck discovered in the Mediterranean Sea near Embiez Island (Var) were investigated because of their morphological analogy with vitrified nuclear waste and of a known and stable environment. These glasses are fractured due to a fast cooling after they were melted (like nuclear glass) and have been altered for 1800 years in seawater. This work results in the development and the validation of a geochemical model able to simulate the alteration of a fractured archaeological glass block over 1800 years. The kinetics associated with the different mechanisms (interdiffusion and dissolution) and the thermodynamic parameters of the model were determined by leaching experiments. The model implemented in HYTEC software was used to simulate crack alteration over 1800 years. The consistency between simulated alteration thicknesses and measured data on glass blocks validate the capacity of the model to predict long-term alteration. This model is able to account for the results from the characterization of crack network and its state of alteration. The cracks in the border zone are the most altered due to a fast renewal of the leaching solution, whereas internal cracks are thin because of complex interactions between glass alteration and transport of elements in solution (influence of initial crack aperture and of the crack sealing). The lowest alteration thicknesses, as well as their variability, can be explained. The analog behavior of archaeological and nuclear glasses from leaching experiments makes possible the transposition of the model to nuclear glass in geological repository. (author)

  7. Physicochemical properties of discontinuous S2-glass fiber reinforced resin composite.

    Science.gov (United States)

    Huang, Qiting; Qin, Wei; Garoushi, Sufyan; He, Jingwei; Lin, Zhengmei; Liu, Fang; Vallittu, Pekka K; Lassila, Lippo V J

    2018-01-30

    The objective of this study was to investigate several physicochemical properties of an experimental discontinuous S2-glass fiber-reinforced resin composite. The experimental composite was prepared by mixing 10 wt% of discontinuous S2-glass fibers with 27.5 wt% of resin matrix and 62.5 wt% of particulate fillers. Flexural strength (FS) and modulus (FM), fracture toughness (FT), work of fracture (WOF), double bond conversion (DC), Vickers hardness, volume shrinkage (VS) and fiber length distribution were determined. These were compared with two commercial resin composites. The experimental composite showed the highest FS, WOF and FT compared with two control composites. The DC of the experimental composite was comparable with controls. No significant difference was observed in VS between the three tested composites. The use of discontinuous glass fiber fillers with polymer matrix and particulate fillers yielded improved physical properties and substantial improvement was associated with the use of S2-glass fiber.

  8. The effect of Al substitution on thermal and mechanical properties of Fe-based bulk metallic glass

    International Nuclear Information System (INIS)

    Ma, R.D.; Zhang, H.F.; Yu, H.S.; Hu, Z.Q.

    2008-01-01

    In this paper, a systematic investigation about the effect of Al substitution on properties of Fe-Cr-Mo-Er-C-B amorphous material, including glass-forming ability (GFA), thermal properties, and mechanical properties was presented. It was found out by X-ray diffraction (XRD) that the glass-forming ability decreased with the increase of Al, when Al reached 7 at%, fully amorphous specimen was not obtained. With regard to thermal parameters, such as glass transition temperature T g , crystallization temperature T x , supercooled liquid region ΔT x , and reduced glass temperature T rg were checked by differential scanning calorimeter. A rather wide supercooled liquid region more than 40 K was found. During compression test, results showed Al substitution slightly improved the fracture strength from 3.4 to 3.7 GPa. The fracture morphology was observed by scanning electron microscopy. Micrographs showed the same cleavage-like fracture in spite of different Al substitution

  9. Strength of metallic glasses at 4.2-300 K

    International Nuclear Information System (INIS)

    Tabachnikova, E.D.

    1987-01-01

    Investigation into temperature dependence of metallic glass strength (Ni 78 Si 8 B 14 ; Fe 40 Ni 38 Mo 4 B 18 ; Fe 25 Ni 55 Si 10 B 1 0 ; Fe 61 Co 20 Si 4 B 15 ) is conducted within 300-4.2 K temperature interval. By the character of σ (T) x dependence and fracture mode the alloys investigated are subdivided into two groups. In 1 group alloys the fracture up to 4.2 K has the character typical of ductile fracture. In the second group alloys fracture acquires brittle character with the temperature decrease

  10. Clinical evaluation of glass ionomer-silver cermet restorations in primary molars: one year results.

    Science.gov (United States)

    Hung, T W; Richardson, A S

    1990-03-01

    Using the half mouth technique, 33 silver amalgam (Dispersalloy) and 40 glass ionomer (Ketec silver) restorations were placed in the primary molars of children aged five to seven years. After one year, 73 restorations were evaluated. The amalgam restorations rated 90-100 per cent alpha for anatomic form and margins with no recurrent caries or fractures. The glass ionomer restorations rated 35 to 55 per cent alpha for anatomic form and margins with 40 per cent being replaced due to fracture of the material. Within the guidelines of this study, glass ionomer silver cermet was not a suitable material for the restoration of interproximal cavities in primary molars.

  11. Identification of green pigments from fragments of Roman mural paintings of three Roman sites from north of Germania Superior

    Science.gov (United States)

    Debastiani, Rafaela; Simon, Rolf; Goettlicher, Joerg; Heissler, Stefan; Steininger, Ralph; Batchelor, David; Fiederle, Michael; Baumbach, Tilo

    2016-10-01

    Roman mural green pigment painting fragments from three Roman sites in the north of the Roman province Germania Superior: Koblenz Stadtwald Remstecken (KOSR), Weißenthurm " Am guten Mann" (WEIS) and Mendig Lungenkärchen (MELU), dating from second and third centuries AD were analyzed. The experiments were performed nondestructively using synchrotron-based scanning macro-X-ray fluorescence (SR-MA-XRF), synchrotron-based scanning micro-X-ray fluorescence (SR-μ-XRF), synchrotron-based X-ray diffraction (SR-XRD) and Raman spectroscopy. Correlation between SR-MA-XRF, SR-μ-XRF elemental map distributions and optical images of scanned areas was mainly found for the elements Ca, Fe and K. With XRF, Fe and K were identified correlated with green pigment, but in samples from two sites, Mendig Lungenkärchen and Weißenthurm " Am guten Mann", also Cu was detected in minor concentration. The results of SR-XRD and Raman spectroscopy were limited to one sample from Weißenthurm " Am guten Mann". In this sample, green earth and calcium carbonate were identified by SR-XRD and, additionally, malachite by Raman spectroscopy.

  12. Fracture, roughness and phase transformation in CAD/CAM milling and subsequent surface treatments of lithium metasilicate/disilicate glass-ceramics.

    Science.gov (United States)

    Alao, Abdur-Rasheed; Stoll, Richard; Song, Xiao-Fei; Abbott, John R; Zhang, Yu; Abduo, Jaafar; Yin, Ling

    2017-10-01

    This paper studied surface fracture, roughness and morphology, phase transformations, and material removal mechanisms of lithium metasilicate/disilicate glass ceramics (LMGC/LDGC) in CAD/CAM-milling and subsequent surface treatments. LMGC (IPS e.max CAD) blocks were milled using a chairside dental CAD/CAM milling unit and then treated in sintering, polishing and glazing processes. X-ray diffraction was performed on all processed surfaces. Scanning electron microscopy (SEM) was applied to analyse surface fracture and morphology. Surface roughness was quantitatively characterized by the arithmetic average surface roughness R a and the maximum roughness R z using desktop SEM-assisted morphology analytical software. The CAD/CAM milling induced extensive brittle cracks and crystal pulverization on LMGC surfaces, which indicate that the dominant removal mechanism was the fracture mode. Polishing and sintering of the milled LMGC lowered the surface roughness (ANOVA, p 0.05). In comparison of all applied fabrication process routes, it is found that CAD/CAM milling followed by polishing and sintering produced the smoothest surface with R a = 0.12 ± 0.08µm and R z = 0.89 ± 0.26µm. Thus , it is proposed as the optimized process route for LMGC/LDGC in dental restorations. This route enables to manufacture LMGC/LDGC restorations with cost effectiveness, time efficiency, and improved surface quality for better occlusal functions and reduced bacterial plaque accumulation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Mechanical properties of glasses impacted by debris or micrometeorites

    Science.gov (United States)

    Kinser, Donald L.; Wiedlocher, David E.

    1992-01-01

    Mechanical strength measurements on five glasses and one glass ceramic exposed on the Long Duration Exposure Facility (LDEF) have revealed no damage exceeding experimental limits of error after exposure. The measurement technique subjected less than 5 percent of the sample surface area to stresses above 90 percent of the failure strength. Seven micrometeorite or space debris impacts occurred at locations which were not in that portion of the sample subjected to greater than 90 percent of the applied stress. In consequence of this, the impact events on the sample were not detected in mechanical strength measurements. The physical form and structure of the impact sites was carefully examined to determine the influence of those events upon stress concentration associated with the impact and the resulting mechanical strength influence. The size of the impact site insofar as it determines flaw size for fracture purposes was examined. Surface topography of the impacts reveals that six of the seven sites display impact melting. The classical melt crater structure is surrounded by a zone of fractured glass. Residual stresses arising from shock compression and from cooling of the impact fused zone cannot be included in fracture mechanics analyses based on simple flaw size analyses. Strategies for refining estimates of mechanical strength degradation by impact events are presented.

  14. Investigation of full-scale high-level waste containment glass blocks. Task 3 characterization of radioactive waste forms a series of final reports (1985-89) - no 24

    International Nuclear Information System (INIS)

    Moncouyoux, J.; Aure, A.; Ladirat, C.

    1991-01-01

    A two-year study of the degree of fracturation in full-scale high-level waste glass blocks was undertaken under contract Fl1W-0182. The project included a theoretical investigation of thermal and mechanical stresses arising in the glass and determination of the fracture-inducing stress distribution in the block, as well as an experimental study based on tomographic examinations performed at the BAM in Berlin on full-scale canisters containing glass cast at Marcoule and on water leach tests at 100 0 C to evaluate the fractured leachable surface area. The Castem code system was used to determine the temperature profiles versus time for the glass package. The mechanical study revealed the impact of removing the package from the furnace on the final stress loading. Controlled cooling of glass blocks must be extremely slow (less than 5 0 C per hour) to have a significant effect on the stress loading. Three series of tomographic experiments were carried out: two on a canister as cast, and a third after relieving the canister stresses. Static and dynamic leach tests were conducted to determine the fracturation factor of the glass blocks. Only static leaching provides satisfactory results. Fracturation factors of 10 to 15 were measured on industrial glass blocks. 50 figs.; 20 tabs.; 3 refs

  15. Mechanical Properties of Stable Glasses Using Nanoindentation

    Science.gov (United States)

    Wolf, Sarah; Liu, Tianyi; Jiang, Yijie; Ablajan, Keyume; Zhang, Yue; Walsh, Patrick; Turner, Kevin; Fakhraai, Zahra

    Glasses with enhanced stability over ordinary, liquid quenched glasses have been formed via the process of Physical Vapor Deposition (PVD) by using a sufficiently slow deposition rate and a substrate temperature slightly below the glass transition temperature. These stable glasses have been shown to exhibit higher density, lower enthalpy, and better kinetic stability over ordinary glass, and are typically optically birefringent, due to packing and orientational anisotropy. Given these exceptional properties, it is of interest to further investigate how the properties of stable glasses compare to those of ordinary glass. In particular, the mechanical properties of stable glasses remain relatively under-investigated. While the speed of sound and elastic moduli have been shown to increase with increased stability, little is known about their hardness and fracture toughness compared to ordinary glasses. In this study, glasses of 9-(3,5-di(naphthalen-1-yl)phenyl)anthracene were deposited at varying temperatures relative to their glass transition temperature, and their mechanical properties measured by nanoindentation. Hardness and elastic modulus of the glasses were compared across substrate temperatures. After indentation, the topography of these films were studied using Atomic Force Microscopy (AFM) in order to further compare the relationship between thermodynamic and kinetic stability and mechanical failure. Z.F. and P.W. acknowledge funding from NSF(DMREF-1628407).

  16. A Directed Network of Greek and Roman Mythology

    OpenAIRE

    Choi, Yeon-Mu; Kim, Hyun-Joo

    2005-01-01

    We study the Greek and Roman mythology using the network theory. We construct a directed network by using a dictionary of Greek and Roman mythology in which the nodes represent the entries listed in the dictionary and we make directional links from an entry to other entries that appear in its explanatory part. We find that this network is clearly not a random network but a directed scale-free network. Also measuring the various quantities which characterize the mythology network, we analyze t...

  17. Ceramic fiber-reinforced monoclinic celsian phase glass-ceramic matrix composite material

    Science.gov (United States)

    Bansal, Narottam P. (Inventor); Dicarlo, James A. (Inventor)

    1994-01-01

    A hyridopolysilazane-derived ceramic fiber reinforced monoclinic celsian phase barium aluminum silicate glass-ceramic matrix composite material is prepared by ball-milling an aqueous slurry of BAS glass powder and fine monoclinic celsian seeds. The fibers improve the mechanical strength and fracture toughness and with the matrix provide superior dielectric properties.

  18. Road Sign Romanization in Oman: The Linguistic Landscape Close-Up

    Science.gov (United States)

    Jamoussi, Rafik; Roche, Thomas

    2017-01-01

    Throughout the Arab Gulf States, bilingual road signs are the norm, employing both Arabic and a romanized counterpart for the large expatriate population. The existing romanization is inconsistent, with potentially misleading variant spellings of place names signposting the region. This study provides a linguistic analysis of signs on the arterial…

  19. WILLIAM GURNEE SINNIGEN - 20TH CENTURY CLASSICIST AND ROMAN HISTORIAN: BIOGRAPHY & BIBLIOGRAPHY

    Directory of Open Access Journals (Sweden)

    Matthew Gray Marsh

    2016-04-01

    Full Text Available William Gurnee Sinnigen was a Classicist and Roman historian, active in the mid-to-late 20th century. Trained at the University of Michigan by noted Roman administrative historian Arthur E. R. Boak, Sinnigen continued his mentor’s work in administrative history, producing several articles on different aspects of Roman and Byzantine administrative topics.  Sinnigen was also responsible for the revision and update of Boak’s acclaimed textbook on Roman history, as well as Charles Alexander Robinson’s textbook on Ancient history.  This article will provide a brief biography of Professor Sinnigen, along with a bibliography of his published works and reviews by other scholars of his work.

  20. Comparison of glass surfaces as a countertop material to existing surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Turo, Laura A.; Winschell, Abigail E.

    2011-09-01

    Gleen Glass, a small production glass company that creates countertops, was selected for the Technology Assistance Program through Pacific Northwest National Laboratory. Gleen Glass was seeking material property analysis comparing glass as a countertop material to current surfaces (i.e. marble, granite and engineered stone). With samples provided from Gleen Glass, testing was done on granite, marble, and 3 different glass surfaces ('Journey,' 'Pebble,' and 'Gleen'). Results showed the glass surfaces have a lower density, lower water absorption, and are stronger in compressive and flexural tests as compared to granite and marble. Thermal shock tests showed the glass failed when objects with a high thermal mass are placed directly on them, whereas marble and granite did not fracture under these conditions.

  1. The ‘enemy within’ the post-Vatican II Roman Catholic Church

    Directory of Open Access Journals (Sweden)

    Graham A. Duncan

    2013-05-01

    Full Text Available The Second Vatican Council (1962–1965 is regarded as one of the most significant processes in the ecumenical church history of the 20th century. At that time, a younger generation of Roman Catholic theologians began to make their mark in the church and within the ecumenical theological scene. Their work provided an ecumenical bridge between the Reforming and the Roman Catholic ecclesiastical traditions, notwithstanding the subsequent negative response of the Roman church hierarchy. Despite important advances, recent pontificates significantly altered the theological landscape and undermined much of the enthusiasm and commitment to unity. Roman Catholic theological dissent provided common ground for theological reflection. Those regarded as the ‘enemy within’ have become respected colleagues in the search for truth in global ecclesiastical perspective. This article will use the distinction between the history and the narratives of Vatican II.

  2. Tikuvõileivaduell / Roman Zaštšerinski ; interv. Jaanus Kulli

    Index Scriptorium Estoniae

    Zaštšerinski, Roman, 1978-

    2008-01-01

    Intervjuu kokk Roman Zaštšerinskiga, kes valmistas koos Imre Kosega ette Vabariigi Presidendi iseseisvuspäeva vastuvõtu menüü. Vt. samas: Roman Zaštšerinski menüü vabariigi presidendi vastuvõtul

  3. Molybdenum sealing glass-ceramic composition

    International Nuclear Information System (INIS)

    Eagan, R.J.

    1976-01-01

    A glass-ceramic composition is described having low hydrogen and helium permeability properties, along with high fracture strength, and a thermal coefficient of expansion similar to that of molybdenum. The composition is adaptable for hermetically sealing to molybdenum at temperatures between 900 and about 950 0 C to form a hermetically sealed insulator body

  4. Three Roman Innkeepers

    OpenAIRE

    Tatarin, Milovan

    2009-01-01

    In the critical publication of Dundo Maroje which in 1930 was edited for the seventh book of the edition Stari pisci hrvatski (Old Croatian writers) by Milan Rešetar, »three Roman innkeepers« are named as dramatis personae. They appear on the stage three times: act one, scene one; act two, scene nine; act four, scene nine. The aim of this work is to establish how many inns and how many innkeepers appear in the comedy and are their lines mixed.

  5. Comparative experimental study of dynamic compressive strength of mortar with glass and basalt fibres

    Directory of Open Access Journals (Sweden)

    Kruszka Leopold

    2015-01-01

    Full Text Available Specimen reinforced with glass and basalt fibers were prepared using Standard Portland cement (CEM I, 52.5 R as prescribed by EN 197-1 and standard sand, in accordance with EN 196-1. From this cementitious mixture, a reference cement mortar without fibers was first prepared. Compressive strength, modulus of elasticity, and mod of fracture were determined for all specimens. Static and dynamic properties were investigated using Instron testing machine and split Hopkinson pressure bar, respectively. Content of the glass fibers in the mortar does not influence the fracture stress at static loading conditions in a clearly observed way. Moreover at dynamic range 5% content of the fiber results in a significant drop of fracture stress. Analysis of the basalt fibers influence on the fracture stress shows that optimal content of this reinforcement is equal to 3% for both static and dynamic loading conditions. Further increase of the fiber share gives the opposite effect, i.e. drop of the fracture stress.

  6. Comparative experimental study of dynamic compressive strength of mortar with glass and basalt fibres

    Science.gov (United States)

    Kruszka, Leopold; Moćko, Wojciech; Fenu, Luigi; Cadoni, Ezio

    2015-09-01

    Specimen reinforced with glass and basalt fibers were prepared using Standard Portland cement (CEM I, 52.5 R as prescribed by EN 197-1) and standard sand, in accordance with EN 196-1. From this cementitious mixture, a reference cement mortar without fibers was first prepared. Compressive strength, modulus of elasticity, and mod of fracture were determined for all specimens. Static and dynamic properties were investigated using Instron testing machine and split Hopkinson pressure bar, respectively. Content of the glass fibers in the mortar does not influence the fracture stress at static loading conditions in a clearly observed way. Moreover at dynamic range 5% content of the fiber results in a significant drop of fracture stress. Analysis of the basalt fibers influence on the fracture stress shows that optimal content of this reinforcement is equal to 3% for both static and dynamic loading conditions. Further increase of the fiber share gives the opposite effect, i.e. drop of the fracture stress.

  7. Milk intake and risk of mortality and fractures in women and men: cohort studies.

    Science.gov (United States)

    Michaëlsson, Karl; Wolk, Alicja; Langenskiöld, Sophie; Basu, Samar; Warensjö Lemming, Eva; Melhus, Håkan; Byberg, Liisa

    2014-10-28

    To examine whether high milk consumption is associated with mortality and fractures in women and men. Cohort studies. Three counties in central Sweden. Two large Swedish cohorts, one with 61,433 women (39-74 years at baseline 1987-90) and one with 45,339 men (45-79 years at baseline 1997), were administered food frequency questionnaires. The women responded to a second food frequency questionnaire in 1997. Multivariable survival models were applied to determine the association between milk consumption and time to mortality or fracture. During a mean follow-up of 20.1 years, 15,541 women died and 17,252 had a fracture, of whom 4259 had a hip fracture. In the male cohort with a mean follow-up of 11.2 years, 10,112 men died and 5066 had a fracture, with 1166 hip fracture cases. In women the adjusted mortality hazard ratio for three or more glasses of milk a day compared with less than one glass a day was 1.93 (95% confidence interval 1.80 to 2.06). For every glass of milk, the adjusted hazard ratio of all cause mortality was 1.15 (1.13 to 1.17) in women and 1.03 (1.01 to 1.04) in men. For every glass of milk in women no reduction was observed in fracture risk with higher milk consumption for any fracture (1.02, 1.00 to 1.04) or for hip fracture (1.09, 1.05 to 1.13). The corresponding adjusted hazard ratios in men were 1.01 (0.99 to 1.03) and 1.03 (0.99 to 1.07). In subsamples of two additional cohorts, one in males and one in females, a positive association was seen between milk intake and both urine 8-iso-PGF2α (a biomarker of oxidative stress) and serum interleukin 6 (a main inflammatory biomarker). High milk intake was associated with higher mortality in one cohort of women and in another cohort of men, and with higher fracture incidence in women. Given the observational study designs with the inherent possibility of residual confounding and reverse causation phenomena, a cautious interpretation of the results is recommended. © Michaëlsson et al 2014.

  8. [A maxillary premolar reconstruction with a glass fiber reinforced post].

    Science.gov (United States)

    Viţalariu, Anca Mihaela; Antohe, Magda; Bahrim, Delia; Tatarciuc, Monica

    2006-01-01

    This paper presents the case of a 37 years old female patient who needed a reconstruction of an endodontic treated' second maxillary premolar. The patient presented large areas of occlusal abrasion caused by bruxism, therefore the solution consisted of a reconstruction with a non-metallic post reinforced with glass fibers. In such cases, the excessive occlusal forces developed by bruxism can produce a radicular fracture if the tooth would be reconstructed with a rigid metallic post. The glass-fiber reinforced post has some important qualities, which render it more suitable in most clinical cases: it is easy to use; has the ability to bond with restorative resins; decreases the risk of tooth fracture and provides better esthetics.

  9. Initial Examination of Low Velocity Sphere Impact of Glass Ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Morrissey, Timothy G [ORNL; Fox, Ethan E [ORNL; Wereszczak, Andrew A [ORNL; Ferber, Mattison K [ORNL

    2012-06-01

    This report summarizes US Army TARDEC sponsored work at Oak Ridge National Laboratory (ORNL) involving low velocity (< 30 m/s or < 65 mph) sphere impact testing of two materials from the lithium aluminosilicate family reinforced with different amounts of ceramic particulate, i.e., glass-ceramic materials, SCHOTT Resistan{trademark}-G1 and SCHOTT Resistan{trademark}-L. Both materials are provided by SCHOTT Glass (Duryea, PA). This work is a follow-up to similar sphere impact studies completed by the authors on PPG's Starphire{reg_sign} soda-lime silicate glass and SCHOTT BOROFLOAT{reg_sign} borosilicate glass. A gas gun or a sphere-drop test setup was used to produce controlled velocity delivery of silicon nitride (Si{sub 3}N{sub 4}) spheres against the glass ceramic tile targets. Minimum impact velocities to initiate fracture in the glass-ceramics were measured and interpreted in context to the kinetic energy of impact and the elastic property mismatch between sphere and target material. Quasistatic spherical indentation was also performed on both glass ceramics and their contact damage responses were compared to those of soda-lime silicate and borosilicate glasses. Lastly, variability of contact damage response was assessed by performing spherical indentation testing across the area of an entire glass ceramic tile. The primary observations from this low velocity (< 30 m/s or < 65 mph) testing were: (1) Resistan{trademark}-L glass ceramic required the highest velocity of sphere impact for damage to initiate. Starphire{reg_sign} soda-lime silicate glass was second best, then Resistan{trademark}-G1 glass ceramic, and then BOROFLOAT{reg_sign} borosilicate glass. (2) Glass-ceramic Resistan{trademark}-L also required the largest force to initiate ring crack from quasi-static indentation. That ranking was followed, in descending order, by Starphire{reg_sign} soda-lime silicate glass, Resistan{trademark}-G1 glass ceramic, and BOROFLOAT{reg_sign} borosilicate glass

  10. On the acoustics of ancient Greek and Roman theaters.

    Science.gov (United States)

    Farnetani, Andrea; Prodi, Nicola; Pompoli, Roberto

    2008-09-01

    The interplay of architecture and acoustics is remarkable in ancient Greek and Roman theaters. Frequently they are nowadays lively performance spaces and the knowledge of the sound field inside them is still an issue of relevant importance. Even if the transition from Greek to Roman theaters can be described with a great architectural detail, a comprehensive and objective approach to the two types of spaces from the acoustical point of view is available at present only as a computer model study [P. Chourmouziadou and J. Kang, "Acoustic evolution of ancient Greek and Roman theaters," Appl. Acoust. 69, re (2007)]. This work addresses the same topic from the experimental point of view, and its aim is to provide a basis to the acoustical evolution from Greek to Roman theater design. First, by means of in situ and scale model measurements, the most important features of the sound field in ancient theaters are clarified and discussed. Then it has been possible to match quantitatively the role of some remarkable architectural design variables with acoustics, and it is seen how this criterion can be used effectively to define different groups of ancient theaters. Finally some more specific wave phenomena are addressed and discussed.

  11. Influence of various bonding techniques on the fracture strength of thin CAD/CAM-fabricated occlusal glass-ceramic veneers.

    Science.gov (United States)

    Yazigi, Christine; Kern, Matthias; Chaar, Mohamed Sad

    2017-11-01

    To evaluate the efficiency of immediate dentin sealing and the effects of different bonding protocols on the fracture strength of CAD/CAM occlusal veneers bonded to exposed dentin. Ninety-six extracted maxillary premolars were initially divided into three main groups with 32 specimens each: without immediate dentin sealing, immediate dentin sealing/total etching and immediate dentin sealing/selective etching. Teeth were identically prepared in the dentin to receive occlusal veneers of 0.8mm thickness, milled from lithium disilicate ceramic blocks (IPS e.max CAD). Each main group was later subdivided, according to the pre-cementation surface etching protocol (total/selective), into two subgroups with 16 specimens each. All restorations were adhesively bonded using a resin cement (Variolink Esthetic). Half of the specimens of each subgroup were subjected to thermo-dynamic loading in a chewing simulator with 1,200,000 cycles at 10kg load. The other half and the surviving specimens were subjected to quasi-static loading until failure. Statistical analysis was performed using three-way ANOVA and Tukey's post-hoc tests. All specimens except one survived the artificial aging. A significantly higher fracture strength of restorations (p ≤ 0.001) was obtained when immediate dentin sealing was followed regardless of the etching method with values ranging from a minimum of 1122 ± 336N to a maximum of 1853 ± 333N. Neither the pre-cementation treatment nor the artificial aging had a statistical significant effect on the fracture strength. Immediate dentin sealing protocol is recommended whenever dentin is exposed during the preparation for thin glass-ceramic occlusal veneers. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Waste Not, Want Not: An Inexpensive Glass-Ceramic from Waste

    Czech Academy of Sciences Publication Activity Database

    Wu, J. P.; Rawlings, R. D.; Boccaccini, A. R.; Dlouhý, Ivo; Chlup, Zdeněk

    2006-01-01

    Roč. 85, č. 5 (2006), s. 29-32 ISSN 0002-7812 R&D Projects: GA ČR(CZ) GA106/05/0495 Institutional research plan: CEZ:AV0Z20410507 Keywords : glass ceramic s * fracture toughness * flexural strength Subject RIV: JH - Ceramic s, Fire-Resistant Materials and Glass Impact factor: 0.210, year: 2006 http://www. ceramic bulletin.org/2006-05.asp

  13. Healing Gods, Heroes and Rituals in the Graeco-Roman World

    Directory of Open Access Journals (Sweden)

    Panayotis Pachis

    2016-05-01

    Full Text Available This editorial introduces the articles published within the OLH Special Collection, ‘Healing Gods, Heroes and Rituals in the Graeco-Roman World’. The first two articles in this collection interrogate the figures of specific healing gods. Olympia Panagiotidou’s article ‘Asclepius’ Myths and Healing Narratives: Counter-Intuitive Concepts and Cultural Expectations’ focuses on the curative features that defined the image of Asclepius, the most famous of the healing gods. The next article in the collection, ‘The Fate of a Healing Goddess: Ocular Pathologies, the Antonine Plague, and the Ancient Roman Cult of Bona Dea’ by Leonardo Ambasciano, interrogates the religious figure of another healing agent: the Italian goddess Bona Dea who was particularly venerated in Rome and in the region of Latium and whose cult reveals the way in which ancient Roman androcentric control over women was institutionalised through religious figures.  The third article in the collection, Audrey Ferlut’s ‘Goddesses as Consorts of the Healing Gods in 'Gallia Belgica' and the 'Germaniae': Forms of Cult and Ritual Practices’ considers the impact that cults dedicated to gods and goddesses had on populations in the wider area of the Roman Empire, focusing on the Northern provinces of the Western Roman Empire ('Gallia Belgica' and the 'Germaniae'. The collection’s final article, ‘From Textual Reception to Textual Codification: Thessalos and the Quest for Authenticity’ by Spyros Piperakis, moves the discussion from the question of cult practices to ‘alternative’ healing therapies in antiquity. Piperakis deals with astrological medicine, one of many alternative therapeutic methods that became popular during the Hellenistic and Roman period.  Taken together, the articles in ‘Healing Gods, Heroes and Rituals in the Graeco-Roman World’ demonstrate that we need to approach the study of ancient myths and cults within their socio-cultural context

  14. Effect of Lithium Disilicate Reinforced Liner Treatment on Bond and Fracture Strengths of Bilayered Zirconia All-Ceramic Crown

    Directory of Open Access Journals (Sweden)

    Yong-Seok Jang

    2018-01-01

    Full Text Available This study was performed to evaluate the effect of a lithium-disilicate spray-liner application on both the bond strength between zirconia cores and heat-pressed lithium-disilicate glass-ceramic veneers, and the fracture strength of all-ceramic zirconia crowns. A lithium-disilicate reinforced liner was applied on the surface of a zirconia core and lithium-disilicate glass-ceramic was veneered on zirconia through heat press forming. Microtensile and crown fracture tests were conducted in order to evaluate, respectively, the bonding strength between the zirconia cores and heat pressed lithium-disilicate glass-ceramic veneers, and the fracture strength of bilayered zirconia all-ceramic crowns. The role of lithium-disilicate spray-liner at the interface between zirconia and lithium-disilicate glass-ceramic veneers was investigated through surface and cross-sectional analyses. We confirmed that both the mean bonding strength between the zirconia ceramics and lithium-disilicate glass-ceramic veneers and the fracture strength of the liner-treated groups were significantly higher than those of the untreated groups, which resulted, on the one hand, from the chemical bonding at the interface of the zirconia and lithium-disilicate liner, and, on the other, from the existence of a microgap in the group not treated with liner.

  15. Study of mosaic glasses from the Alpha Basilica (sixth century of Nikopolis in Epirus, Greece

    Directory of Open Access Journals (Sweden)

    Cesare Fiori

    2014-02-01

    Full Text Available After collecting the essential historical, archaeological, and artistic information relative to the ancient town of Nikopolis in Epirus and its Alpha (or Doumetios Basilica, built in the sixth century A.D., glass tesserae belonging to degraded and lost parts of the mosaic floors of the basilica were analysed, determining their chemical composition and the possible presence of crystalline phases. As in all glasses produced in the Mediterranean area in that epoch, they are soda-lime silicate glasses, in part with lead, obtained using natron as a flux. The typology of the glass corresponds to that of Roman glasses, of the first centuries A.D., and is the same as that employed for the basilicas of Ravenna in the fifth and sixth centuries; in particular, a comparison was made with the glass tesserae of the St Vitale Basilica. The technological base for producing coloured glasses is also practically the same as that of the mosaic glasses of Ravenna. In particular, antimony was used as an opacifying element and a fusion was carried out under reducing conditions to obtain red glass with microparticles of metallic copper. Thus, it can be supposed there was a common source of production of the mosaic glasses used in Nikopolis and Ravenna in the sixth century and that this source was in the Near Orient.

  16. LA REPRÉSENTATION DU COUPLE DANS QUELQUES ROMANS QUÉBÉCOIS RÉCEN LA REPRÉSENTATION DU COUPLE DANS QUELQUES ROMANS QUÉBÉCOIS RÉCENTS

    Directory of Open Access Journals (Sweden)

    Irène Oore

    2012-10-01

    Full Text Available Nous avons entrepris d’examiner le couple dans une dizaine de romans écrits durant une décennie (entre 1993 et 2003.Nous avons entrepris d’examiner le couple dans une dizaine de romans écrits durant une décennie (entre 1993 et 2003.

  17. The Roman Bazaar

    DEFF Research Database (Denmark)

    Bang, Peter Fibiger

    The Roman bazaar et et komparativt studie af handels og markedsforhold i Romerriget. Det er bogens tese, at vi bedre forstår den økonomiske udvikling i Romerriget hvis vi skifter vores sammenligningsgrundlag fra den tidligt moderne, europæiske kapitalisme til store agrare eller tributære imperier......, som fx Mogulernes rige i Indien. Hovedemner er den imperiale mobilisering af den agrare produktion og markedernes ofte fragmenterede karakter. Det sidste punkt understøttes vha. Clifford Geertz' analyse af Bazaar-markeder....

  18. The pen behind the sword: power, literacy and the Roman army

    Directory of Open Access Journals (Sweden)

    John Wilkes

    2001-10-01

    Full Text Available The creation and cohesion of the Roman empire owed much to the spread of literacy through the provinces and the use of texts as an instrument of government. An important manifestation of this is the role of the written word in the Roman army, exemplified by the diplomas that granted Roman citizenship and other privileges to auxiliary soldiers on completion of their military service. Margaret Roxan, one of the Institute's honorary research fellows, has studied these diplomas for many years, and her achievement was honoured at an international conference in London in May 2002.

  19. Stress-corrosion mechanisms in silicate glasses

    International Nuclear Information System (INIS)

    Ciccotti, Matteo

    2009-01-01

    The present review is intended to revisit the advances and debates in the comprehension of the mechanisms of subcritical crack propagation in silicate glasses almost a century after its initial developments. Glass has inspired the initial insights of Griffith into the origin of brittleness and the ensuing development of modern fracture mechanics. Yet, through the decades the real nature of the fundamental mechanisms of crack propagation in glass has escaped a clear comprehension which could gather general agreement on subtle problems such as the role of plasticity, the role of the glass composition, the environmental condition at the crack tip and its relation to the complex mechanisms of corrosion and leaching. The different processes are analysed here with a special focus on their relevant space and time scales in order to question their domain of action and their contribution in both the kinetic laws and the energetic aspects.

  20. Replacement of glass particles by multidirectional short glass fibers in experimental composites: Effects on degree of conversion, mechanical properties and polymerization shrinkage.

    Science.gov (United States)

    Bocalon, Anne C E; Mita, Daniela; Narumyia, Isabela; Shouha, Paul; Xavier, Tathy A; Braga, Roberto Ruggiero

    2016-09-01

    To test the null hypothesis that the replacement of a small fraction of glass particles with random short glass fibers does not affect degree of conversion (DC), flexural strength (FS), fracture toughness (FT) and post-gel polymerization shrinkage (PS) of experimental composites. Four experimental photocurable composites containing 1 BisGMA:1 TEGDMA (by weight) and 60vol% of fillers were prepared. The reinforcing phase was constituted by barium glass particles (2μm) and 0%, 2.5%, 5.0% or 7.5% of silanated glass fibers (1.4mm in length, 7-13μm in diameter). DC (n=4) was obtained using near-FTIR. FS (n=10) was calculated via biaxial flexural test and FT (n=10) used the "single edge notched beam" method. PS at 5min (n=8) was determined using the strain gage method. Data were analyzed by ANOVA/Tukey test (DC, FS, PS) or Kruskal-Wallis/Dunn's test (FT, alpha: 5% for both tests). DC was similar among groups (p>0.05). Only the composite containing 5.0% of fibers presented lower FS than the control (pglass fibers significantly increased fracture toughness and reduced post-gel shrinkage of experimental composites. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  1. Tough and strong porous bioactive glass-PLA composites for structural bone repair.

    Science.gov (United States)

    Xiao, Wei; Zaeem, Mohsen Asle; Li, Guangda; Bal, B Sonny; Rahaman, Mohamed N

    2017-08-01

    Bioactive glass scaffolds have been used to heal small contained bone defects but their application to repairing structural bone is limited by concerns about their mechanical reliability. In the present study, the addition of an adherent polymer layer to the external surface of strong porous bioactive glass (13-93) scaffolds was investigated to improve their toughness. Finite element modeling (FEM) of the flexural mechanical response of beams composed of a porous glass and an adherent polymer layer predicted a reduction in the tensile stress in the glass with increasing thickness and elastic modulus of the polymer layer. Mechanical testing of composites with structures similar to the models, formed from 13-93 glass and polylactic acid (PLA), showed trends predicted by the FEM simulations but the observed effects were considerably more dramatic. A PLA layer of thickness -400 µm, equal to -12.5% of the scaffold thickness, increased the load-bearing capacity of the scaffold in four-point bending by ~50%. The work of fracture increased by more than 10,000%, resulting in a non-brittle mechanical response. These bioactive glass-PLA composites, combining bioactivity, high strength, high work of fracture and an internal architecture shown to be conducive to bone infiltration, could provide optimal implants for healing structural bone defects.

  2. Long-term damage to glass in Paris in a changing environment.

    Science.gov (United States)

    Ionescu, Anda; Lefèvre, Roger-Alexandre; Brimblecombe, Peter; Grossi, Carlota M

    2012-08-01

    Glass weathering depends mainly on its chemical composition: Si-Ca-K mediaeval glass is low durable, while Si-Ca-Na Roman as well as modern glass are very durable. Mediaeval glass is subject to the superficial leaching of K and Ca ions leading to the formation of a hydrated silica-gel layer. Both types of glass develop a superficial stratum of deposited atmospheric particles cemented by crystals of gypsum (and syngenite in the case of Si-Ca-K glass), leading to an impairment of the optical properties: decrease of transparency and increase of haze. Dose-response functions established for the two types of glass reveal that haze depends only on pollution parameters (PM, SO(2), NO(2)), while leaching depends both on pollution and climate parameters (RH, T, SO(2), NO(2)). Instrumental records are available for temperature in Paris from 1800. Air pollution in Paris was estimated from statistics of fuel use from 1875 to 1943, measurements that started in the 1950s and projections across the 21st century. The estimated annual rate of haze development indicates a gradual rise from the 16th century. The increasing importance of coal as a fuel through the 19th century and enhanced sulphur dioxide concentration make a rapid increase in haze formation, which reaches a peak about 1950. The likely damage to mediaeval glass follows a rather similar pattern. The period of damage from aggressive pollutants looks later and for a briefer time in Paris than in London. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Effect of nanoparticles and nanofibers on Mode I fracture toughness of fiber glass reinforced polymeric matrix composites

    International Nuclear Information System (INIS)

    Kelkar, Ajit D.; Mohan, Ram; Bolick, Ronnie; Shendokar, Sachin

    2010-01-01

    Graphical abstract: Use of alumina nanoparticles and TEOS electrospun nanofibers at the interfaces of glass fiber plies to develop delamination resistant epoxy polymeric composites and compare their Mode I fracture toughness characteristics. - Abstract: In the recent past, the research involving the fabrication and processing of reinforced polymer nanocomposites has increased significantly. These new materials are enabling in the discovery, development and incorporation of improved nanocomposite materials with effective manufacturing methodologies for several defense and industrial applications. These materials eventually will allow the full utilization of nanocomposites in not only reinforcing applications but also in multifunctional applications where sensing and the unique optical, thermal, electrical and magnetic properties of nanoparticles can be combined with mechanical reinforcement to offer the greatest opportunities for significant advances in material design and function. This paper presents two methods and material systems for processing and integration of the nanomaterial constituents, namely: (a) dispersing alumina nanoparticles using high energy mixing (using ultrasonication, high shear mixing and pulverization) and (b) electrospinning technique to manufacture nanofibers. These reinforced polymer nanocomposites and the processing methodologies are likely to provide effective means of improving the interlaminar properties of woven fiber glass composites compared to the traditional methods such as stitching and Z-pinning. The electrospinning technology relies on the creation of nanofibers with improved molecular orientation with reduced concentration of fiber imperfections and crystal defects. Electrospinning process utilizes surface tension effects created by electrostatic forces acting on liquid droplets, creating numerous nanofibers. These nanofibers thus have potential to serve as through-the-thickness reinforcing agents in woven composites. While

  4. Influence of ceramic thickness and ceramic materials on fracture resistance of posterior partial coverage restorations.

    Science.gov (United States)

    Bakeman, E M; Rego, N; Chaiyabutr, Y; Kois, J C

    2015-01-01

    This study evaluated the influence of ceramic thickness and ceramic materials on fracture resistance of posterior partial coverage ceramic restorations. Forty extracted molars were allocated into four groups (n=10) to test for two variables: 1) the thickness of ceramic (1 mm or 2 mm) and 2) the ceramic materials (a lithium disilicate glass-ceramic [IPS e.max] or leucite-reinforced glass ceramic [IPS Empress]). All ceramic restorations were luted with resin cement (Variolink II) on the prepared teeth. These luted specimens were loaded to failure in a universal testing machine, in the compression mode, with a crosshead speed of 1.0 mm/min. The data were analyzed using two-way analysis of variance and the Tukey Honestly Significantly Different multiple comparison test (α =0.05). The fracture resistance revealed a significant effect for materials (pceramic was not significant (p=0.074), and the interaction between the thickness of ceramic and the materials was not significant (p=0.406). Mean (standard deviation) fracture resistance values were as follows: a 2-mm thickness of a lithium disilicate bonded to tooth structure (2505 [401] N) revealed a significantly higher fracture resistance than did a 1-mm thickness of leucite-reinforced (1569 [452] N) and a 2-mm thickness of leucite-reinforced ceramic bonded to tooth structure (1716 [436] N) (pceramic at 1-mm thickness (2105 [567] N) and at 2-mm thickness. Using a lithium disilicate glass ceramic for partial coverage restoration significantly improved fracture resistance compared to using a leucite-reinforced glass ceramic. The thickness of ceramic had no significant effect on fracture resistance when the ceramics were bonded to the underlying tooth structure.

  5. Remaining stress-state and strain-energy in tempered glass fragments

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik

    2016-01-01

    to the fragmentation process and some authors e.g. Barsom (J Am Ceram Soc 51(2):75, 1968), Gulati (Glass processing days, Tamglass Engineering Oy, Tampere, 1997), Warren (Fractography of glasses and ceramics IV, Alfred University, Alfred, 2001) and Tandon and Glass (Fracture mechanics of ceramics—active materials......When tempered glass breaks, it shatters into relatively small pieces depending on the residual stress state in the glass. This has been known for centuries and is currently used in standards for classifying whether a piece of glass is tempered or not. However, the process of fragmentation...... is complex and only a few, relatively simple, models have been suggested for predicting the fragment size. The full theoretical explanation is still to be found and this work aims at providing another brick to the puzzle. The strain-energy present in tempered glass is obviously contributing...

  6. Measurements of interface fracture properties of composite materials

    International Nuclear Information System (INIS)

    Ashkenazi, D.; Bank-Sills, L.; Travitzky, N.; Eliasi, R.

    1998-01-01

    In this investigation, interface Fracture properties are measured. To this end, glass/epoxy Brazilian disk specimens are studied. In order to calibrate the specimen, a numerical procedure is used. The finite element method is employed to derive stress intensity factors as a function of loading angle and crack length. By means of the weight friction method together with finite elements, a correction to the stress intensity factors for residual thermal stresses is obtained. These are combined to determine the critical interface energy release rate as a function of phase angle Tom the measured load and crack length at Fracture. A series of tests on a glass/epoxy material pair were carried out. It may be observed from the results that the residual thermal stresses resulting from the material mismatch greatly affect the interface toughness values

  7. Machinable glass-ceramics forming as a restorative dental material.

    Science.gov (United States)

    Chaysuwan, Duangrudee; Sirinukunwattana, Krongkarn; Kanchanatawewat, Kanchana; Heness, Greg; Yamashita, Kimihiro

    2011-01-01

    MgO, SiO(2), Al(2)O(3), MgF(2), CaF(2), CaCO(3), SrCO(3), and P(2)O(5) were used to prepare glass-ceramics for restorative dental materials. Thermal properties, phases, microstructures and hardness were characterized by DTA, XRD, SEM and Vickers microhardness. Three-point bending strength and fracture toughness were applied by UTM according to ISO 6872: 1997(E). XRD showed that the glass crystallized at 892°C (second crystallization temperature+20°C) for 3 hrs consisted mainly of calcium-mica and fluorapatite crystalline phases. Average hardness (3.70 GPa) closely matched human enamel (3.20 GPa). The higher fracture toughness (2.04 MPa√m) combined with the hardness to give a lower brittleness index (1.81 µm(-1/2)) which indicates that they have exceptional machinability. Bending strength results (176.61 MPa) were analyzed by Weibull analysis to determine modulus value (m=17.80). Machinability of the calcium mica-fluorapatite glass-ceramic was demonstrated by fabricating with CAD/CAM.

  8. Effects of alpha radiation on hardness and toughness of the borosilicate glass applied to radioactive wastes immobilization

    International Nuclear Information System (INIS)

    Prado, Miguel Oscar; Bernasconi, Norma B. Messi de; Bevilacqua, Arturo Miguel; Arribere, Maria Angelica; Heredia, Arturo D.; Sanfilippo, Miguel

    1999-01-01

    Borosilicate german glass SG7 samples, obtained by frit sintering, were irradiated with different fluences of thermal neutrons in the nucleus of a nuclear reactor. The nuclear reaction 10 B(n,α) 7 Li, where the 10 B isotope is one of the natural glass components, was used to generate alpha particles throughout the glass volume. The maximum alpha disintegration per unit volume achieved was equivalent to that accumulated in a borosilicate glass with nuclear wastes after 3.8 million years. Through Vickers indentations values for microhardness, stress for 50% fracture probability (Weibull statistics) and estimation of the toughness were obtained as a function of alpha radiation dose. Two counterbalanced effects were found: that due to the disorder created by the alpha particles in the glass and that due to the annealing during irradiation (temperature below 240 deg C). Considering the alpha radiation effect, glasses tend decrease Vickers hardness, and to increase thr 50% fracture probability stress with the dose increase. (author)

  9. Magnetic and electromagnetic prospections at the Roman city of Hadrianopolis, southern Albania

    Science.gov (United States)

    Schettino, Antonio; Perna, Roberto; Pierantoni, Pietro Paolo; Ghezzi, Annalisa; Tassi, Luca; Sforzini, David

    2017-04-01

    We report on a combined magnetic-GPR survey performed in 2015-2017 at the ancient Roman city of Hadrianopolis, located in southern Albania, in the context of the project Teatri Antichi Riuniti (TAU). The collected data supplemented previous archaeological surveys performed by the University of Macerata with the aim of promoting the valley and starting the realization of an archaeological park. Hadrianopolis was founded through a reorganization of a previous Hellenistic settlement. Starting from 2015, magnetic and GPR surveys were carried out in Hadrianopolis in order to determine the urban framework. The collected data revealed the existence of structures organized along two main different patterns, which have been interpreted as due to the superposition of Roman buildings and Late Antiquity structures. In fact, the arrangement of structures in the studied area shows a regular urban organization of Roman type separated by a less regular disposition of the buildings that can be attributed to the Byzantine age. The latter arrangement is superimposed on the previous Roman structures. A stone wall, clearly identified by the combination of magnetic anomalies and GPR images, separates the Byzantine seattlement from the genuine Roman sector.

  10. Human parasites in the Roman World: health consequences of conquering an empire.

    Science.gov (United States)

    Mitchell, Piers D

    2017-01-01

    The archaeological evidence for parasites in the Roman era is presented in order to demonstrate the species present at that time, and highlight the health consequences for people living under Roman rule. Despite their large multi-seat public latrines with washing facilities, sewer systems, sanitation legislation, fountains and piped drinking water from aqueducts, we see the widespread presence of whipworm (Trichuris trichiura), roundworm (Ascaris lumbricoides) and Entamoeba histolytica that causes dysentery. This would suggest that the public sanitation measures were insufficient to protect the population from parasites spread by fecal contamination. Ectoparasites such as fleas, head lice, body lice, pubic lice and bed bugs were also present, and delousing combs have been found. The evidence fails to demonstrate that the Roman culture of regular bathing in the public baths reduced the prevalence of these parasites. Fish tapeworm was noted to be widely present, and was more common than in Bronze and Iron Age Europe. It is possible that the Roman enthusiasm for fermented, uncooked fish sauce (garum) may have facilitated the spread of this helminth. Roman medical practitioners such as Galen were aware of intestinal worms, explaining their existence and planning treatment using the humoural theory of the period.

  11. Structural integrity testing of glass-ceramic/molybdenum vacuum tube frames

    International Nuclear Information System (INIS)

    Spears, R.K.

    1980-01-01

    In this study, vacuum tube subassemblies made of glass-ceramic insulators sealed to inner and outer molybdenum frames were loaded in compression to failure with a tensile test machine. Several factors were varied in processing these subassemblies. These factors included etching and nonetching of molybdenum piece parts, annealing and nonannealing of subassemblies, and vapor and non-vapor honing of insulators after sealing. After failure, the subassemblies were examined for fracture patterns. In most cases, fracture started at points near the lower portion of the inner sleeve-insulator interface. More load was carried by subassemblies having molybdenum piece parts that were acid etched. No difference appeared between the strength of subassemblies having annealed and nonannealed glass-ceramic insulators. Parts with vapor-honed insulators failed at substantially lower loads

  12. Analysis of the Design Criteria for Ancient Greek and Roman Catapults

    DEFF Research Database (Denmark)

    Paasch, Kasper

    2011-01-01

    This paper will give a short overview of use of COMSOL Multiphysics for analyzing ancient Greek and Roman catapults with the main focus on the energy storing torsion springs. Catapults have been known and used in the Greek and Roman world from around 399 BC and a fully standardized design for pow...

  13. The regenerative medicine coalition. Interview with Frank-Roman Lauter.

    Science.gov (United States)

    Lauter, Frank-Roman

    2012-11-01

    Frank-Roman Lauter, Secretary General of the recently launched Regenerative Medicine Coalition, explains how the coalition was formed and what they hope to achieve. Frank-Roman Lauter has served as Secretary General of the Regenerative Medicine Coalition since 2012, and as Head of Business Development at Berlin-Brandenburg Center for Regenerative Therapies since 2007. Frank-Roman Lauter's interest is the organization of academic infrastructures to promote efficient translation of research findings into new therapies. He co-organizes joined strategy development for regenerative medicine clusters from seven European countries (FP7-EU Project) and has initiated cooperation between the California Institute for Regenerative Medicine and the German Federal Ministry for Education & Research, resulting in a joined funding program. Recently, he cofounded the international consortium of Regenerative Medicine translational centers (RMC; www.the-rmc.org ). Trained as a molecular biologist at the Max-Planck Institute in Berlin-Dahlem and at Stanford, he has 16 years of experience as an entrepreneur and life science manager in Germany and the USA.

  14. Reflections on the Cultural Encounter between the Jews and the Greeks and Romans in Jewish Coin Iconography of the Hellenistic-Roman Period

    DEFF Research Database (Denmark)

    Lykke, Anne

    2017-01-01

    Contrary to the written and archaeological sources, the numismatic material from the Persian, Hellenistic, and particularly the Roman Imperial periods in Palestine constitutes an almost uninterrupted material source from which detailed knowledge can be drawn concerning the political, cultural and......—by extension—even social processes. In this article examples reflecting the results of the cultural encounter between the Jewish and the Greco-Roman world are discussed, which are well illustrated by the differences in the iconography of the Jewish coinages of the first century BCE and first century CE...

  15. The Recovery and Restoration of Roman Wall Paintings in Southeast Spain

    Directory of Open Access Journals (Sweden)

    Victoria Santiago Godos

    2013-11-01

    Full Text Available Recovery of the Roman wall painting in the southeast Spanish is done, by a party's own excavations in the archaeological site, where you can find this mural in two ways, still located in the walls of Roman villas or at the foot of these walls collapsed, fragmented and even buried, making it necessary cooperation in the recovery work of the archaeologist and restorer. You can also recall Roman wall paintings in the collections of archaeological museums, as many boxes remain innumerable multitude of fragments of mural pieces found in excavations and record stored there pending further study, grading and restoration. Examples of the above are discussed.

  16. Thracians in the Roman imperial navy

    DEFF Research Database (Denmark)

    Bekker-Nielsen, Tønnes

    2017-01-01

    The Roman fleets of the imperial period were crewed by provincials, not by Italians. Of the sailors and soldiers whose names and geographical origin are attested epigraphically (on military diplomas or epitaphs) almost 15% claim a Thracian origin; and among these, the majority identify themselves...

  17. The traces of roman metallurgy in Eastern Serbia

    Directory of Open Access Journals (Sweden)

    Petković Sofija

    2009-01-01

    Full Text Available The archaeological traces of the Roman mining and metallurgy in eastern Serbia are rather frequent but insufficiently studied and published. Three mining-metallurgical regions abounding in gold, silver, copper, iron and lead could be distinguished there: 1. the upper course of the Pek river, metalla Pincensia, 2. the area between Bor, Zlot, Crna Reka and Rgotina and 3. the area in the river basin of Beli Timok, two latter ones had been organized as territoria metallorum. The archeometallurgical sites confirmed by investigations are: Kraku lu Jordan at the confluence of the Brodica river and the Pek river, Rudna Glava, Tilva Roš in Bor, Gamzigrad - Romuliana, Rgotina near Zaječar and Timacum Minus in the village Ravna near Knjaževac. Roman mining-metallurgical activities in eastern Serbia flourished from the end of the 3rd century, were interrupted by the invasion of Huns in AD 441. and restored in the time of emperors Anastasius and Justin I, in the end of the 5th - beginning of the 6th centuries. The Roman mining-metallurgical centers functioned in the 6th century until the Slav invasion in the beginning of the 7th century.

  18. Milk consumption during teenage years and risk of hip fractures in older adults.

    Science.gov (United States)

    Feskanich, Diane; Bischoff-Ferrari, Heike A; Frazier, A Lindsay; Willett, Walter C

    2014-01-01

    Milk consumption during adolescence is recommended to promote peak bone mass and thereby reduce fracture risk in later life. However, its role in hip fracture prevention is not established and high consumption may adversely influence risk by increasing height. To determine whether milk consumption during teenage years influences risk of hip fracture in older adults and to investigate the role of attained height in this association. Prospective cohort study over 22 years of follow-up in more than 96,000 white postmenopausal women from the Nurses' Health Study and men aged 50 years and older from the Health Professionals Follow-up Study in the United States. Frequency of consumption of milk and other foods during ages 13 to 18 years and attained height were reported at baseline. Current diet, weight, smoking, physical activity, medication use, and other risk factors for hip fractures were reported on biennial questionnaires. Cox proportional hazards models were used to calculate relative risks (RRs) of first incidence of hip fracture from low-trauma events per glass (8 fl oz or 240 mL) of milk consumed per day during teenage years. During follow-up, 1226 hip fractures were identified in women and 490 in men. After controlling for known risk factors and current milk consumption, each additional glass of milk per day during teenage years was associated with a significant 9% higher risk of hip fracture in men (RR = 1.09; 95% CI, 1.01-1.17). The association was attenuated when height was added to the model (RR = 1.06; 95% CI, 0.98-1.14). Teenage milk consumption was not associated with hip fractures in women (RR = 1.00 per glass per day; 95% CI, 0.95-1.05). Greater milk consumption during teenage years was not associated with a lower risk of hip fracture in older adults. The positive association observed in men was partially mediated through attained height.

  19. PIXE and XRF Analysis of Roman Denarii

    Science.gov (United States)

    Fasano, Cecilia; Raddell, Mark; Manukyan, Khachatur; Stech, Edward; Wiescher, Michael

    2017-09-01

    A set of Roman Denarii from the republican to the imperial period (140BC-240AD) has been studied using X-ray fluorescent (XRF) scanning and proton induced x-ray emission (PIXE) techniques. XRF and PIXE are commonly used in the study of cultural heritage objects because they are nondestructive. The combination of these two methods is also unique because of the ability to penetrate the sample with a broader spectrum of depths and energies than either could achieve on its own. The coins are from a large span of Roman history and their analysis serves to follow the economic and political change of the era using the relative silver and copper contents in each sample. In addition to analyzing the samples, the study sought to compare these two common analysis techniques and to explore the use of a standard to examine any shortcomings in either of the methods. Data sets were compared and then adjusted to a calibration curve which was created from the analysis of a number of standard solutions. The concentrations of the standard solutions were confirmed using inductively coupled plasma spectroscopy. Through this we were able to assemble results which will progress the basis of understanding of PIXE and XRF techniques as well as increase the wealth of knowledge of Ancient Roman currency.

  20. Precision diamond grinding of ceramics and glass

    Energy Technology Data Exchange (ETDEWEB)

    Smith, S.; Paul, H.; Scattergood, R.O.

    1988-12-01

    A new research initiative will be undertaken to investigate the effect of machine parameters and material properties on precision diamond grinding of ceramics and glass. The critical grinding depth to initiate the plastic flow-to-brittle fracture regime will be directly measured using plunge-grind tests. This information will be correlated with machine parameters such as wheel bonding and diamond grain size. Multiaxis grinding tests will then be made to provide data more closely coupled with production technology. One important aspect of the material property studies involves measuring fracture toughness at the very short crack sizes commensurate with grinding damage. Short crack toughness value`s can be much less than the long-crack toughness values measured in conventional fracture tests.

  1. SOI silicon on glass for optical MEMS

    DEFF Research Database (Denmark)

    Larsen, Kristian Pontoppidan; Ravnkilde, Jan Tue; Hansen, Ole

    2003-01-01

    and a final sealing at the interconnects can be performed using a suitable polymer. Packaged MEMS on glass are advantageous within Optical MEMS and for sensitive capacitive devices. We report on experiences with bonding SOI to Pyrex. Uniform DRIE shallow and deep etching was achieved by a combination......A newly developed fabrication method for fabrication of single crystalline Si (SCS) components on glass, utilizing Deep Reactive Ion Etching (DRIE) of a Silicon On Insulator (SOI) wafer is presented. The devices are packaged at wafer level in a glass-silicon-glass (GSG) stack by anodic bonding...... of an optimized device layout and an optimized process recipe. The behavior of the buried oxide membrane when used as an etch stop for the through-hole etch is described. No harmful buckling or fracture of the membrane is observed for an oxide thickness below 1 μm, but larger and more fragile released structures...

  2. Evaluation of Different Restoration Combinations Used in the Reattachment of Fractured Teeth: A Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    Nagihan Guven

    2018-01-01

    Full Text Available Objective. The purpose of this study was to test different restoration combinations used for constructing fractured endodontically treated incisors by reattaching their fractured fragments. Methods. Seven types of 3-D FEM mathematical root canal-filled models were generated, simulating cases of (OB reattaching fractured fragments; (CrPL reattaching fractured fragments + ceramic palatinal laminate; (CmPL reattaching fractured fragments + composite palatinal laminate; (CM reattaching fractured fragments + coronal 1/3 of the root was filled using core material; (BP reattaching fractured fragments + glass fiber post; (CP composite resin restoration + glass fiber post; and (OC composite resin restoration. A 100-N static oblique force was applied to the simulated teeth with 135° on the node at 2 mm above the cingulum to analyze the stress distribution at the tooth. Results. For enamel tissue, the highest stress values were observed in model BP, and the lowest stress values were observed in model CmPL. For dentine tissue, the highest stress concentrations were observed around the fracture line for all models. Conclusions. Reattachment of fractured fragments by bonding may be preferred as a restoration option for endodontically treated incisors; also, palatinal laminate decreases the stress values at tooth tissues, especially at the enamel and the fracture line.

  3. X-ray fluorescence analysis and optical emission spectrometry of an roman mirror from Tomis, Romania

    International Nuclear Information System (INIS)

    Belc, M.; Bogoi, M.; Ionescu, D.; Guita, D.; Caiteanu, S.; Caiteanu, D.

    2000-01-01

    The miscellaneous population of Roman Empire, their diverse cultural tradition, their ability to assimilate the roman civilization spirits, had determined a permanent reassessment superimposed upon the roman contribution. Analysis was undertaken using optical emission spectrometry and non-destructive X-ray fluorescence. X-ray fluorescence analysis is a well-established method and is often used in archaeometry and other work dealing with valuable objects pertaining to the history of art and civilization. Roman mirror analysed has been found not to be made of speculum (a high tin bronze). (authors)

  4. Improvement of the stability of hydroxyapatite through glass ceramic reinforcement.

    Science.gov (United States)

    Ha, Na Ra; Yang, Zheng Xun; Hwang, Kyu Hong; Kim, Tae Suk; Lee, Jong Kook

    2010-05-01

    Hydroxyapatite has achieved significant application in orthopedic and dental implants due to its excellent biocompatibility. Sintered hydroxyapatites showed significant dissolution, however, after their immersion in water or simulated body fluid (SBF). This grain boundary dissolution, even in pure hydroxyapatites, resulted in grain separation at the surfaces, and finally, in fracture. In this study, hydroxyapatite ceramics containing apatite-wollastonite (AW) or calcium silicate (SG) glass ceramics as additives were prepared to prevent the dissolution. AW and SG glass ceramics were added at 0-7 wt% and powder-compacted uniaxially followed by firing at moisture conditions. The glass phase was incorporated into the hydroxyapatite to act as a sintering aid, followed by crystallization, to improve the mechanical properties without reducing the biocompatibility. As seen in the results of the dissolution test, a significant amount of damage was reduced even after more than 14 days. TEM and SEM showed no decomposition of HA to the secondary phase, and the fracture toughness increased, becoming even higher than that of the commercial hydroxyapatite.

  5. Greek and Roman Mythology: English, Mythology.

    Science.gov (United States)

    Hargraves, Richard; Kenzel, Elaine

    The aim of the Quinmester course "Greek and Roman Mythology" is to help students understand mythological references in literature, art, music, science and technology. The subject matter includes: creation myths; myths of gods and heroes; mythological allusions in astrology, astronomy, literature, science, business, puzzles, and everyday…

  6. Fratografia em vidros Fractography in glasses

    Directory of Open Access Journals (Sweden)

    J. M. F. Coelho

    2000-09-01

    Full Text Available A análise da superfície de fratura é um método extremamente confiável para se identificar as razões da falha em um material, uma vez que o caminho percorrido pela trinca fornece informações importantes sobre sua origem e direção de propagação, além das distribuições de tensões no momento da fratura, as causas de sua iniciação, a interação da trinca com a microestrutura e a seqüência de propagação da mesma. Nos vidros e cerâmicos, as principais características morfológicas da superfície de fratura são a origem, o espelho de fratura, a região de névoa ou bruma ("mist" e a região de ramificação de trincas ("hackle". Além destas características, outras marcas importantes podem ocorrer na superfície de fratura de vidros, tais como: linhas de "Wallner", escarpas de aceleração e desaceleração, ramificações de rotação ("twist hackle", asas de gaivotas ("gull wings" e os rastros de ramificação ("wake hackle". As características morfológicas descritas são bem definidas nos vidros, uma vez que estes materiais são homogêneos, isotrópicos e não possuem cristais que interfiram com a propagação da trinca.Fracture surface analysis is a very reliable method to identify the causes of a material failure, since the crack propagation path allows the identification of the crack origin and the propagation direction, the stress state at the moment of the fracture, the causes of fracture initiation, interaction of the crack with the microstructure and the crack propagation sequence. In glasses and ceramics, the most important morphologic features of the fracture surface are the fracture origin, the fracture mirror, the mist and the hackle. Along with these fracture marks, other important surface features can be present too, for instance: "Wallner" lines, scarps, twist hackle, gull wings and the wake hackle. The above fracture surface features are very well defined in glasses, since these materials are homogeneous

  7. Crack fronts and damage in glass at the nanometre scale

    International Nuclear Information System (INIS)

    Marliere, Christian; Prades, Silke; Celarie, Fabrice; Dalmas, Davy; Bonamy, Daniel; Guillot, Claude; Bouchaud, Elisabeth

    2003-01-01

    We have studied the low-speed fracture regime for different glassy materials with variable but controlled length scales of heterogeneity in a carefully controlled surrounding atmosphere. By using optical and atomic force microscopy techniques, we tracked, in real-time, the crack tip propagation at the nanometre scale over a wide velocity range (10 -3 -10 -12 m s -1 and below). The influence of the heterogeneities on this velocity is presented and discussed. Our experiments reveal also - for the first time - that the crack progresses through nucleation, growth and coalescence of nanometric damage cavities within the amorphous phase. This may explain the large fluctuations observed in the crack tip velocities for the smallest values. This behaviour is very similar to that involved, at the micrometric scale, in ductile fracture. The only difference is very probably due to the related length scales (nanometric instead of micrometric). The consequences of such a nano-ductile fracture mode observed at a temperature far below the glass transition temperature, T g , in glass is also discussed

  8. Characterization of microstructure of Si3N4 whisker reinforced glass ceramic

    International Nuclear Information System (INIS)

    Han, Byoung Sung; Choi, Shung Shaon

    1993-01-01

    Glass ceramics, especially fiber-reinforced composite ceramics, have attracted a great deal of attention in improving the reliability of ceramic components because of the improvement in various mechanical properties. Through hot-pressing and sintering, 225 cordierite was transformed with glass ceramic and mullite phase. Particularly glass glain size increased with the increasing of the sintering temperature and the heat treatment enhance the toughness and hardness of materials. Like the increased sintering temperature, the roughness increased with increasing whisker vol.%. In case of whisker-rinforced glass ceramic, the fracture surface of samples has been associated with a whisker orientation of samples. (Author)

  9. Electronic hybridisation implications for the damage-tolerance of thin film metallic glasses.

    Science.gov (United States)

    Schnabel, Volker; Jaya, B Nagamani; Köhler, Mathias; Music, Denis; Kirchlechner, Christoph; Dehm, Gerhard; Raabe, Dierk; Schneider, Jochen M

    2016-11-07

    A paramount challenge in materials science is to design damage-tolerant glasses. Poisson's ratio is commonly used as a criterion to gauge the brittle-ductile transition in glasses. However, our data, as well as results in the literature, are in conflict with the concept of Poisson's ratio serving as a universal parameter for fracture energy. Here, we identify the electronic structure fingerprint associated with damage tolerance in thin film metallic glasses. Our correlative theoretical and experimental data reveal that the fraction of bonds stemming from hybridised states compared to the overall bonding can be associated with damage tolerance in thin film metallic glasses.

  10. Effect of elevated temperature on the tensile strength of Napier/glass-epoxy hybrid reinforced composites

    Science.gov (United States)

    Ridzuan, M. J. M.; Majid, M. S. Abdul; Afendi, M.; Firdaus, A. Z. Ahmad; Azduwin, K.

    2017-11-01

    The effects of elevated temperature on the tensile strength of Napier/glass-epoxy hybrid reinforced composites and its morphology of fractured surfaces are discussed. Napier/glass-epoxy hybrid reinforced composites were fabricated by using vacuum infusion method by arranging Napier fibres in between sheets of woven glass fibres. Napier and glass fibres were laminated with estimated volume ratios were 24 and 6 vol. %, respectively. The epoxy resin was used as matrix estimated to 70 vol. %. Specimens were tested to failure under tension at a cross-head speed of 1 mm/min using Universal Testing Machine (Instron) with a load cell 100 kN at four different temperatures of RT, 40°C, 60°C and 80°C. The morphology of fractured surface of hybrid composites was investigated by field emission scanning electron microscopy. The result shows reduction in tensile strength at elevated temperatures. The increase in the temperature activates the process of diffusion, and generates critical stresses which cause the damage at first-ply or at the centre of the hybrid plate, as a result lower the tensile strength. The observation of FESEM images indicates that the fracture mode is of evolution of localized damage, from fibre/matrix debonding, matric cracking, delamination and fibre breakage.

  11. Mechanistic interpretation of glass reaction: Input to kinetic model development

    International Nuclear Information System (INIS)

    Bates, J.K.; Ebert, W.L.; Bradley, J.P.; Bourcier, W.L.

    1991-05-01

    Actinide-doped SRL 165 type glass was reacted in J-13 groundwater at 90 degree C for times up to 278 days. The reaction was characterized by both solution and solid analyses. The glass was seen to react nonstoichiometrically with preferred leaching of alkali metals and boron. High resolution electron microscopy revealed the formation of a complex layer structure which became separated from the underlying glass as the reaction progressed. The formation of the layer and its effect on continued glass reaction are discussed with respect to the current model for glass reaction used in the EQ3/6 computer simulation. It is concluded that the layer formed after 278 days is not protective and may eventually become fractured and generate particulates that may be transported by liquid water. 5 refs., 5 figs. , 3 tabs

  12. Cementation of Glass-Ceramic Posterior Restorations: A Systematic Review

    Science.gov (United States)

    van den Breemer, Carline R. G.; Gresnigt, Marco M. M.; Cune, Marco S.

    2015-01-01

    Aim. The aim of this comprehensive review is to systematically organize the current knowledge regarding the cementation of glass-ceramic materials and restorations, with an additional focus on the benefits of Immediate Dentin Sealing (IDS). Materials and Methods. An extensive literature search concerning the cementation of single-unit glass-ceramic posterior restorations was conducted in the databases of MEDLINE (Pubmed), CENTRAL (Cochrane Central Register of Controlled Trials), and EMBASE. To be considered for inclusion, in vitro and in vivo studies should compare different cementation regimes involving a “glass-ceramic/cement/human tooth” complex. Results and Conclusions. 88 studies were included in total. The in vitro data were organized according to the following topics: (micro)shear and (micro)tensile bond strength, fracture strength, and marginal gap and integrity. For in vivo studies survival and quality of survival were considered. In vitro studies showed that adhesive systems (3-step, etch-and-rinse) result in the best (micro)shear bond strength values compared to self-adhesive and self-etch systems when luting glass-ceramic substrates to human dentin. The highest fracture strength is obtained with adhesive cements in particular. No marked clinical preference for one specific procedure could be demonstrated on the basis of the reviewed literature. The possible merits of IDS are most convincingly illustrated by the favorable microtensile bond strengths. No clinical studies regarding IDS were found. PMID:26557651

  13. On the interfacial fracture of porcelain/zirconia and graded zirconia dental structures.

    Science.gov (United States)

    Chai, Herzl; Lee, James J-W; Mieleszko, Adam J; Chu, Stephen J; Zhang, Yu

    2014-08-01

    Porcelain fused to zirconia (PFZ) restorations are widely used in prosthetic dentistry. However, their susceptibility to fracture remains a practical problem. The failure of PFZ prostheses often involves crack initiation and growth in the porcelain, which may be followed by fracture along the porcelain/zirconia (P/Z) interface. In this work, we characterized the process of fracture in two PFZ systems, as well as a newly developed graded glass-zirconia structure with emphases placed on resistance to interfacial cracking. Thin porcelain layers were fused onto Y-TZP plates with or without the presence of a glass binder. The specimens were loaded in a four-point-bending fixture with the thin porcelain veneer in tension, simulating the lower portion of the connectors and marginal areas of a fixed dental prosthesis (FDP) during occlusal loading. The evolution of damage was observed by a video camera. The fracture was characterized by unstable growth of cracks perpendicular to the P/Z interface (channel cracks) in the porcelain layer, which was followed by stable cracking along the P/Z interface. The interfacial fracture energy GC was determined by a finite-element analysis taking into account stress-shielding effects due to the presence of adjacent channel cracks. The resulting GC was considerably less than commonly reported values for similar systems. Fracture in the graded Y-TZP samples occurred via a single channel crack at a much greater stress than for PFZ. No delamination between the residual glass layer and graded zirconia occurred in any of the tests. Combined with its enhanced resistance to edge chipping and good esthetic quality, graded Y-TZP emerges as a viable material concept for dental restorations. Copyright © 2014 Acta Materialia Inc. All rights reserved.

  14. The force required to fracture endodontically roots restored with ...

    African Journals Online (AJOL)

    Nigerian Journal of Clinical Practice ... Objective: To evaluate the effect of various materials as intra‑orifice barriers on the force required fracture roots. ... prepared, but not filled), filling using glass ionomer cement, nano‑hybrid composite resin, ...

  15. Tourist valorization of roman imperial city Felix Romuliana

    Directory of Open Access Journals (Sweden)

    Berić Dejan

    2012-01-01

    Full Text Available The tourism industry is a great potential for the development of Serbia. The main characteristics of the existing and potential tourist offer of Serbia are interesting and diverse natural resources and cultural and historical heritage. Felix Romuliana, established palace of the Roman emperor Galerius, is located in the valley of the Black Timok, near Zaječar and the village of Gamzigrad in eastern Serbia. The palace was built in the late third and early fourth century, as a testamentary construction. This is where the Roman emperor was buried and included among the gods. It is the best preserved example of Roman palatial architecture which in 2007 was added to the List of World Heritage of UNESCO. One of the key tasks of this paper is to point out ways of promoting and popularizing this tourism potential that can be used as a resource for the development of cultural tourism and as such strengthen the position of Serbia''s tourist offer in Europe. The aim of this paper is contained in the presentation of the site Felix Romuliana and extraction of the most important attractiveness through valorization, which on the bases of historical and cultural significance may be activated for tourism purposes. [Projekat Ministarstva nauke Republike Srbije, br. 176020

  16. Fracture response of SiOC based composites on dynamic loading

    Czech Academy of Sciences Publication Activity Database

    Halasová, Martina; Černý, Martin; Strachota, Adam; Chlup, Zdeněk; Dlouhý, Ivo

    2015-01-01

    Roč. 50, č. 11 (2015), s. 1547-1554 ISSN 0021-9983 R&D Projects: GA ČR GAP107/12/2445 Institutional support: RVO:68081723 ; RVO:61389013 ; RVO:67985891 Keywords : SiOC glass * basalt reinforcement * woven fabric * impact strength * energy consumption * fracture surface Subject RIV: JL - Materials Fatigue, Friction Mechanics; JH - Ceramics, Fire-Resistant Materials and Glass (USMH-B); CD - Macromolecular Chemistry (UMCH-V) Impact factor: 1.242, year: 2015

  17. Kuulus Roman Viktjuki Teater Tallinnas / Meelis Kapstas

    Index Scriptorium Estoniae

    Kapstas, Meelis, 1963-

    2000-01-01

    26. ja 27. mail Vene Kultuurikeskuses Roman Viktjuki Teatri külalisetendused. Mängitakse R. Viktjuki lavastust "Kellavärgiga apelsin" Anthony Burgessi romaani järgi ja Viktjuki versiooni Oscar Wilde'i kurbmängust "Salomé"

  18. Effect of the metallic glass volume fraction on the mechanical properties of Zr-based metallic glass reinforced with porous W composite

    International Nuclear Information System (INIS)

    Zhang, X.Q.; Wang, L.; Xue, Y.F.; Cheng, X.W.; Wang, Y.D.; Nie, Z.H.; Zhang, H.F.; Fu, H.M.; Ma, L.L.; Ren, Y.

    2013-01-01

    The mechanical properties of both as-cast and as-extruded Zr-based metallic glass reinforced with tungsten composites with 33, 28, and 21 vol. % of metallic glass were investigated under quasi-static compression at strain rates from 10 −4 s −1 to 10 −1 s −1 . These two types of composites exhibited a strain rate sensitivity exponent that increased with the increase of the tungsten volume fraction. Compared to the composites with 33 and 21 vol. % of the metallic glass, the two types of composites with 28 vol. % of the metallic glass phase exhibited superior fracture energies. The in-situ compression test on the as-cast composites using high-energy synchrotron X-ray diffraction (HEXRD) revealed that the yield stress of the tungsten phase increased with a decrease in the metallic glass volume fraction. The as-cast composite with 28 vol. % of the metallic glass exhibited relatively great mechanical properties compared to the composites that contained 33 and 21 vol. % of the metallic glass. This result was attributed to the great coupling of the load distribution between the two phases and the high lattice strain in the tungsten phase.

  19. Comparative investigation of mortars from Roman Colosseum and cistern

    Energy Technology Data Exchange (ETDEWEB)

    Silva, D.A. [Department of Civil and Environmental Engineering, 725 Davis Hall 94720-1710, University of California at Berkeley, Berkeley, CA (United States)]. E-mail: denise@ecv.ufsc.br; Wenk, H.R. [Department of Earth and Planetary Science, 497 McCone 94720-4767, University of California at Berkeley, Berkeley, CA (United States); Monteiro, P.J.M. [Department of Civil and Environmental Engineering, 725 Davis Hall 94720-1710, University of California at Berkeley, Berkeley, CA (United States)

    2005-11-01

    Mortar from the Roman Colosseum and a Roman cistern from Albano Laziale were characterized with optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and thermal analysis (differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)). The different techniques provided consistent results that the mortar of the Colosseum is mainly calcareous lime, while the mortar of the cistern is pozzolanic siliceous material. The study highlights the capabilities of the different methods for the analysis of cement. For routine analysis XRD is adequate but for characterization of poorly crystalline phases FT-IR and TGA have definite advantages.

  20. Comparative investigation of mortars from Roman Colosseum and cistern

    International Nuclear Information System (INIS)

    Silva, D.A.; Wenk, H.R.; Monteiro, P.J.M.

    2005-01-01

    Mortar from the Roman Colosseum and a Roman cistern from Albano Laziale were characterized with optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and thermal analysis (differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)). The different techniques provided consistent results that the mortar of the Colosseum is mainly calcareous lime, while the mortar of the cistern is pozzolanic siliceous material. The study highlights the capabilities of the different methods for the analysis of cement. For routine analysis XRD is adequate but for characterization of poorly crystalline phases FT-IR and TGA have definite advantages

  1. Tests of a Roman Pot Prototype for the TOTEM Experiment

    OpenAIRE

    Deile, M.; Alagoz, E.; Anelli, G.M.; Antchev, G.A.; Ayache, M.; Caspers, F.; Dimovasili, E.; Dinapoli, R.; Drouhin, F.D.; Eggert, K.; Escourrou, L.; Fochler, O.; Gill, K.; Grabit, R.; Haug, F.

    2005-01-01

    The TOTEM collaboration has developed and tested the first prototype of its Roman Pots to be operated in the LHC. TOTEM Roman Pots contain stacks of 10 silicon detectors with strips oriented in two orthogonal directions. To measure proton scattering angles of a few microradians, the detectors will approach the beam centre to a distance of 10 sigma + 0.5 mm (= 1.3 mm). Dead space near the detector edge is minimised by using two novel "edgeless" detector technologies. The silicon detectors are ...

  2. Fracture induced electromagnetic radiation

    International Nuclear Information System (INIS)

    Frid, V; Rabinovitch, A; Bahat, D

    2003-01-01

    In our laboratory, we combine accurate electromagnetic radiation (EMR) measurements during fracture of rocks (carbonate and igneous) and transparent materials (glass, PMMA and glass ceramics) with careful fractographic methods. A critical analysis of experimental observations, accumulated here during the last decade together with supporting material from the works of other authors are used in this study to demonstrate the failure of all current models to explain the properties of EMR arising from fracture. The basic elements of a new model are proposed. These are (a) the EMR amplitude increases as long as the crack continues to grow, since new atomic bonds are severed and their contribution is added to the EMR. As a result, the atoms on both sides of the bonds are moved to 'non-equilibrium' positions relative to their steady state ones and begin to oscillate collectively in a manner similar to Debye model bulk oscillations - 'surface vibrational optical waves'; (b) when the crack halts, the waves and the EMR pulse amplitude decay by relaxation. These basic elements are already enough to describe the characteristics of the experimentally obtained isolated individual EMR pulses. These characteristics include the shape of the EMR pulse envelope, and the frequency, time duration and rise - fall time of the pulse

  3. Fracture induced electromagnetic radiation

    Energy Technology Data Exchange (ETDEWEB)

    Frid, V [Geological and Environmental Sciences Department, Deichmann Rock Mechanics Laboratory of the Negev, Ben Gurion University of the Negev, Beer Sheva (Israel); Rabinovitch, A [Physics Department, Deichmann Rock Mechanics Laboratory of the Negev, Ben Gurion University of the Negev, Beer Sheva (Israel); Bahat, D [Geological and Environmental Sciences Department, Deichmann Rock Mechanics Laboratory of the Negev, Ben Gurion University of the Negev, Beer Sheva (Israel)

    2003-07-07

    In our laboratory, we combine accurate electromagnetic radiation (EMR) measurements during fracture of rocks (carbonate and igneous) and transparent materials (glass, PMMA and glass ceramics) with careful fractographic methods. A critical analysis of experimental observations, accumulated here during the last decade together with supporting material from the works of other authors are used in this study to demonstrate the failure of all current models to explain the properties of EMR arising from fracture. The basic elements of a new model are proposed. These are (a) the EMR amplitude increases as long as the crack continues to grow, since new atomic bonds are severed and their contribution is added to the EMR. As a result, the atoms on both sides of the bonds are moved to 'non-equilibrium' positions relative to their steady state ones and begin to oscillate collectively in a manner similar to Debye model bulk oscillations - 'surface vibrational optical waves'; (b) when the crack halts, the waves and the EMR pulse amplitude decay by relaxation. These basic elements are already enough to describe the characteristics of the experimentally obtained isolated individual EMR pulses. These characteristics include the shape of the EMR pulse envelope, and the frequency, time duration and rise - fall time of the pulse.

  4. Crystallization of high-strength nano-scale leucite glass-ceramics.

    Science.gov (United States)

    Theocharopoulos, A; Chen, X; Wilson, R M; Hill, R; Cattell, M J

    2013-11-01

    Fine-grained, high strength, translucent leucite dental glass-ceramics are synthesized via controlled crystallization of finely milled glass powders. The objectives of this study were to utilize high speed planetary milling of an aluminosilicate glass for controlled surface crystallization of nano-scale leucite glass-ceramics and to test the biaxial flexural strength. An aluminosilicate glass was synthesized, attritor or planetary milled and heat-treated. Glasses and glass-ceramics were characterized using particle size analysis, X-ray diffraction and scanning electron microscopy. Experimental (fine and nanoscale) and commercial (Ceramco-3, IPS Empress Esthetic) leucite glass-ceramics were tested using the biaxial flexural strength (BFS) test. Gaussian and Weibull statistics were applied. Experimental planetary milled glass-ceramics showed an increased leucite crystal number and nano-scale median crystal sizes (0.048-0.055 μm(2)) as a result of glass particle size reduction and heat treatments. Experimental materials had significantly (p0.05) strength difference. All other groups' mean BFS and characteristic strengths were found to be significantly different (pglass-ceramics with high flexural strength. These materials may help to reduce problems associated with brittle fracture of all-ceramic restorations and give reduced enamel wear. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  5. Stress corrosion in a borosilicate glass nuclear wasteform

    International Nuclear Information System (INIS)

    Ringwood, A.E.; Willis, P.

    1984-01-01

    The authors discuss a typical borosilicate glass wasteform which, when exposed to water vapour and water for limited periods, exhibits evidence of stress corrosion cracking arising from the interaction of polar OH groups with stressed glass surfaces. Glass wasteforms may experience similar stress corrosion cracking when buried in a geological repository and exposed to groundwaters over an extended period. This would increase the effective surface areas available for leaching by groundwater and could decrease the lifetime of the wasteform. Conventional leach-testing methods are insensitive to the longer-term effects of stress corrosion cracking. It is suggested that specific fracture-mechanics tests designed to evaluate susceptibility to stress corrosion cracking should be used when evaluating the wasteforms for high-level nuclear wastes. (author)

  6. EFFECT OF GAMMA RAY IRRADIATION ON INTERLAMINAR SHEAR STRENGTH OF GLASS FIBER REINFORCED PLASTICS AT 77 K

    International Nuclear Information System (INIS)

    Nishimura, A.; Nishijima, S.; Izumi, Y.

    2008-01-01

    It is known that an organic material is damaged by gamma ray irradiation, and the strength after irradiation has dependence on the gamma ray dose. These issues are important not only to make global understanding of electric insulating performance of glass fiber reinforced plastics (GFRP) under irradiation condition but also to develop new insulation materials. This paper presents the dependence of fracture mode and interlaminar shear strength (ILSS) on the material and the gamma ray irradiation effect on the fracture mode and the ILSS. 6 mm radius loading nose and supports were used to prompt ILS fracture for a short beam test. A 2.5 mm thick small specimen machined out of a 13 mm thick G-10CR GFRP plate (sliced specimen) showed lower ILSS and translaminar shear (TLS) fracture, although the same size specimen prepared from a 2.5 mm G-10CR GFRP plate (non-sliced specimen) showed ILS fracture and the higher ILSS. Both type of specimens showed the degradation of ILSS after gamma ray irradiation. The fracture mode of the non-sliced specimen changed from ILS to TLS fracture and no bending fracture was observed. The resistance to shear deformation of glass cloth/epoxy laminate structure would be damaged by the irradiation

  7. The first Cohort of Cretans, a roman military unit at Timacum Maius

    Directory of Open Access Journals (Sweden)

    Petrović Vladimir P.

    2015-01-01

    Full Text Available Archaeological investigations on the site of Niševac (Timacum Maius have been conducted over a period of eight successive years by the Institute for Balkan Studies in collaboration with the Centre for Tourism, Culture and Sports of Svrljig and the French Bordeaux-based Ausonius Institute. The 2014 campaign came up with nine Roman bricks stamped with inscriptions of the First Cohort of Cretans (Cohors I Cretum built into the walls of a Roman bath. The inscriptions provide evi­dence for the character, chronology and history of the Roman settlement. [Projekat Ministarstva nauke Republike Srbije, br. 177012: Society, spiritual and material culture and communications in prehistory and early history of the Balkans

  8. Imperial Policy and the Integration of Gaul into the Roman Empire

    Science.gov (United States)

    2015-06-12

    ECONOMIC BENEFITS OF EMPIRE From as early as the second century BC Gaul had a taste for the material outputs of the Roman economy. Wine in particular...Rome tolerated the establishment of local Gallic production. This meant the growth in Gaul’s wine consumption benefited Gallic producers and not...exporter of sought after wines . Wine production was not the only industry that benefited from the Roman conquest. Complementing Gallic viticulture

  9. Pagan and Jewish Monotheism according to Varro, Plutarch and St Paul : The Aniconic, Monotheistic Beginnings of Rome’s Pagan Cult – Romans 1.19-25 in a Roman Context

    NARCIS (Netherlands)

    van Kooten, G.H.; Hilhorst, A.; Puech,; Tigchelaar, E.

    2007-01-01

    George H. van Kooten, “Pagan and Jewish Monotheism according to Varro, Plutarch and St Paul: The Aniconic, Monotheistic Beginnings of Rome’s Pagan Cult—Romans 1:19-25 in a Roman Context,” in Flores Florentino: Dead Sea Scrolls and Other Early Jewish Studies in Honour of Florentino García Martínez

  10. developing of antique olympic plays in a roman period at board of different emperors

    Directory of Open Access Journals (Sweden)

    Kasianenko O.G.

    2009-12-01

    Full Text Available Researched the questions of development the Ancient Olympic Games, after the capture Greece territory by the Roman army. This condition and development in future fully depended on the social and political phenomena in Roman society preferring more aggressive types of «spectacles». The direction of quickly changing emperors was represented on status of the competitions. Positive relation authorities to competitions brought to achievement the second «bloom» of the Olympic Games in the Roman period.

  11. Fracture resistance of aluminium oxide and lithium disilicate-based crowns using different luting cements: an in vitro study.

    Science.gov (United States)

    Al-Wahadni, Ahed M; Hussey, David L; Grey, Nicholas; Hatamleh, Muhanad M

    2009-03-01

    The aim of this study was to investigate the fracture resistance of two types of ceramic crowns cemented with two different cements. Forty premolar crowns were fabricated using lithium-disilicate (IPS Empress-2) and glass-infiltrated aluminium-oxide (In-Ceram) ceramic systems. The crowns were divided into four groups (n=10) with Group 1 (IPS Empress-2) and Group 2 (In-Ceram) cemented with glass ionomer cement. Group 3 (IPS Empress-2) and Group 4 (In-Ceram) were cemented with resin cement. Crowns were tested in a universal testing machine at a compressive-load speed of 10 mm/min. Fracture modes were grouped into five categories. One way analysis of variance (ANOVA) and Bonferroni post-hoc tests were used to detect statistical significances (p0.05) on fracture resistance within each ceramic system tested. In-Ceram crowns cemented with either glass ionomer or resin cements exhibited a statistically significantly higher fracture-resistance than IPS Empress-2 crowns (pEmpress-2 and In-Ceram crowns was not affected by the type of cement used for luting. Both In-Ceram and IPS Empress-2 crowns can be successfully luted with the cements tested with In-Ceram exhibiting higher fracture resistance than IPS Empress-2.

  12. The Roman Catholic position on abortion.

    Science.gov (United States)

    Barry, R

    1997-01-01

    This article presents the history and grounds of the official position of the Roman Catholic Church that abortion under any circumstances, including abortion to save the life of the mother, should be prohibited. After an introduction that deplores the lack of mercy shown to killers of abortionists while Catholic priests threatened by pro-abortion forces are not offered protection, the article traces the historic development of the Catholic abortion policy and rebuts arguments that abortion was permitted in the early Christian Church. The next section explains Catholic views on the personhood of a conceptus and refutes the contentions of Joseph Donceel that early abortion should be permitted because of uncertainty about the nature of the conceptus and the possibility of delayed animation. The fourth section of the paper debates the points raised by Susan Teft Nicholson who maintains that the Catholic position regarding abortion rests on the Church's animosity towards sexual pleasure. The paper goes on to criticize Nicholson's claims that the Roman Catholic position on abortion is inconsistent with the Church's own understanding of the Principle of Double Effect because the Church fails to allow abortion in many cases where it would be permissible under the Principle. Section 6 describes the underlying motive of the Roman Catholic Church's abortion position as an attempt to protect the innocent fetus from deliberate death and to justify the Church's application of protection from deliberate killing to those who are innocent of aggressive action. This discussion is followed by a justification of the Church's prohibition of abortion in cases of aggression, such as the aggression ascribed to a fetus when a pregnancy imperials the life of a mother. It is concluded that the US will likely legalize suicide and mercy killing as it has the killing of innocent fetuses who are probably ensouled with personhood and are not formal aggressors.

  13. Comparative Comparison of City and Urbanism during Sassanid Period in Iran and the Ancient Roman

    Directory of Open Access Journals (Sweden)

    Zohre Moqimizade

    2017-02-01

    Full Text Available Sassanid replaced migrating nomads and tribes with urbanization system and concentration of population. Sassanid desire to increase the population was due to the fact that population is the core of urban systems and focus-oriented system. Sassanid tried marching to Syria and Asia Minor to gain population. Immigrant Roman population was accommodated in newly established cities. Romans had structured and deep thinking about urban development, such that their territory was made up of urban units which were connected through a system of roads and bridges. Romans innovation in urban development can be summed up in creating military cities. Sassanid urbanization after the Parthians was influenced by Roman urbanization which is most visible in the shape of Sassanid cities. In this study, while examining cities and urbanization in Sassanid reign and Roman Empire, their influence on each other and their similarities and differences in their urbanization methods were also investigated.

  14. Romanization of Referencing Styles for Arts & Humanities Science Journals in Taiwan

    Directory of Open Access Journals (Sweden)

    Chang-Huei Lin

    2016-12-01

    Full Text Available Based on Big Three referecing styles guides, namely APA, Chicago (Turabian and MLA Style, this study discusses the citation formats in which have been applied and specified for scholarly references in non-English languages, especially in Chinese language scholarly writing. This study targets on those Taiwan journals, indexed by TSSCI, THCI Core, A&HCI, SSCI and Scopus, that use the Romanization of references in Chinese journal. By analyzing their notes for contributors and the real situation of application in the Chinese cited works. In respect of the aforementioned three major referencing styles and the rules made by journals themselves, the findings are as follows: the APA, Chicago, and MLA Styles should be revised according to the practical needs of citing non-English references; academic journal publishers need to specify and provide the guidelines and templates of romanizing references in respect of contributed articles; international citation index databases providers should stipulate and provide their description style for romanizing references, and the government and major academic institutes should put more efforts to assist local scholarly journals to cope with the reference romanization problems, even at promoting a kind of consistent Pinyin principle for referencing styles for Chinese journal publishing in Taiwan.

  15. Safety Concepts in Structural Glass Engineering : Towards an Integrated Approach

    NARCIS (Netherlands)

    Bos, F.P.

    2009-01-01

    This dissertation proposes the Integrated Approach to Structural Glass Safety, based on four clearly defined element safety properties, damage sensitivity, relative resistance, redundancy, and fracture mode. The Element Safety Diagram (ESD) is introduced to provide an easy-to-read graphical

  16. Finnie's notes on fracture mechanics fundamental and practical lessons

    CERN Document Server

    Dharan, C K H; Finnie, Iain

    2016-01-01

    This textbook consists primarily of notes by Iain Finnie who taught a popular course on fracture mechanics at the University of California at Berkeley. It presents a comprehensive and detailed exposition of fracture, the fundamentals of fracture mechanics and procedures for the safe design of engineering components made from metal alloys, brittle materials like glasses and ceramics, and composites. Interesting and practical problems are listed at the end of most chapters to give the student practice in applying the theory. A solutions manual is provided to the instructor. The text presents a unified perspective of fracture with a strong fundamental foundation and practical applications. In addition to its role as a text, this reference would be invaluable for the practicing engineer who is involved in the design and evaluation of components that are fracture critical. This book also: Presents details of derivations of the basic equations of fracture mechanics and the historical context of the development of f...

  17. Roman sophisticated surface modification methods to manufacture silver counterfeited coins

    Science.gov (United States)

    Ingo, G. M.; Riccucci, C.; Faraldi, F.; Pascucci, M.; Messina, E.; Fierro, G.; Di Carlo, G.

    2017-11-01

    By means of the combined use of X-ray photoelectron spectroscopy (XPS), optical microscopy (OM) and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS) the surface and subsurface chemical and metallurgical features of silver counterfeited Roman Republican coins are investigated to decipher some aspects of the manufacturing methods and to evaluate the technological ability of the Roman metallurgists to produce thin silver coatings. The results demonstrate that over 2000 ago important advances in the technology of thin layer deposition on metal substrates were attained by Romans. The ancient metallurgists produced counterfeited coins by combining sophisticated micro-plating methods and tailored surface chemical modification based on the mercury-silvering process. The results reveal that Romans were able systematically to chemically and metallurgically manipulate alloys at a micro scale to produce adherent precious metal layers with a uniform thickness up to few micrometers. The results converge to reveal that the production of forgeries was aimed firstly to save expensive metals as much as possible allowing profitable large-scale production at a lower cost. The driving forces could have been a lack of precious metals, an unexpected need to circulate coins for trade and/or a combinations of social, political and economic factors that requested a change in money supply. Finally, some information on corrosion products have been achieved useful to select materials and methods for the conservation of these important witnesses of technology and economy.

  18. Laser cleaning on Roman coins

    Science.gov (United States)

    Drakaki, E.; Karydas, A. G.; Klinkenberg, B.; Kokkoris, M.; Serafetinides, A. A.; Stavrou, E.; Vlastou, R.; Zarkadas, C.

    Ancient metal objects react with moisture and environmental chemicals to form various corrosion products. Because of the unique character and high value of such objects, any cleaning procedure should guarantee minimum destructiveness. The most common treatment used is mechanical stripping, in which it is difficult to avoid surface damage when employed. Lasers are currently being tested for a wide range of conservation applications. Since they are highly controllable and can be selectively applied, lasers can be used to achieve more effective and safer cleaning of archaeological artifacts and protect their surface details. The basic criterion that motivated us to use lasers to clean Roman coins was the requirement of pulsed emission, in order to minimize heat-induced damages. In fact, the laser interaction with the coins has to be short enough, to produce a fast removal of the encrustation, avoiding heat conduction into the substrate. The cleaning effects of three lasers operating at different wavelengths, namely a TEA CO2 laser emitting at 10.6 μm, an Er:YAG laser at 2.94 μm, and a 2ω-Nd:YAG laser at 532 nm have been compared on corroded Romans coins and various atomic and nuclear techniques have also been applied to evaluate the efficiency of the applied procedure.

  19. A Roman funerary inscription from Smederevo

    Directory of Open Access Journals (Sweden)

    Kovács Péter

    2016-01-01

    Full Text Available In this short paper the authors publish a Hungarian wartime postcard from Smederevo (Serbia, from 1916. It is reported that a Roman gravestone was found on the banks of the Danube and the text of the lost stone monument was also added. The authors intend to interpret the funerary text that was incorrectly transcribed.

  20. 75 FR 1680 - Culturally Significant Objects Imported for Exhibition Determinations: “Roman Art”

    Science.gov (United States)

    2010-01-12

    ... Determinations: ``Roman Art'' SUMMARY: Notice is hereby given of the following determinations: Pursuant to the... FR 19875], I hereby determine that the objects to be included in the exhibition ``Roman Art... that the exhibition or display of the exhibit objects at the Metropolitan Museum of Art, New York, NY...

  1. Mechanical behavior of Fe{sub 75}Mo{sub 5}P{sub 10}C{sub 7.5}B{sub 2.5} bulk-metallic glass under torsional loading

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Xinjian [School of Chemical Engineering and Technology, Tianjin University, 92 Weijin Road, Tianjin 300072 (China); Huang Lu [Department of Materials Science and Engineering, University of Tennessee, TN 37996 (United States); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Chen Xu, E-mail: xchen@tju.edu.cn [School of Chemical Engineering and Technology, Tianjin University, 92 Weijin Road, Tianjin 300072 (China); Liaw, Peter K. [Department of Materials Science and Engineering, University of Tennessee, TN 37996 (United States); An Ke [Neutron Scattering Sciences Division, Oak Ridge National Laboratory, TN 37831 (United States); Zhang Tao [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Wang Gongyao [Department of Materials Science and Engineering, University of Tennessee, TN 37996 (United States)

    2010-11-15

    Research highlights: {yields} Fe{sub 75}Mo{sub 5}P{sub 10}C{sub 7.5}B{sub 2.5} bulk-metallic glass exhibits a brittle characteristic under torsional loading. {yields} The BMG occurs in a tensile mode failure under torsional loading. {yields} A slight cyclic-hardening behavior was observed in the initial loading cycles during torsional-fatigue tests. {yields} The torsional fatigue-fracture surface consists of three main regions. - Abstract: Pure- and cyclic-torsional studies were conducted on a Fe{sub 75}Mo{sub 5}P{sub 10}C{sub 7.5}B{sub 2.5} (atomic percent, at.%) bulk-metallic glass at room temperature for an understanding of its damage and fracture mechanisms. Under pure-torsional loading, the metallic glass exhibited very little plastic strain before fracture. The fracture initiated along the maximum tensile-stress plane, which is about 45{sup o} to the axial direction. The shear-fracture strength ({approx}510 MPa) is much lower than the compressive-fracture strength ({approx}3280 MPa), which suggests that different deformation mechanisms be present under various loading modes. Instead of an apparent vein-type structure, the fracture morphologies revealed a crack-initiation site, a mirror region, a mist region, and a hackle region. Under cyclic-torsional loading, fatigue cracks initiated from casting defects, and propagate generally along the maximum tensile-stress plane. A slight cyclic-hardening behavior was observed in initial loading steps. The fatigue-fracture surface consists of three main regions: the fatigue crack-initiation, crack-propagation, and final-fast-fracture areas. The striations resulting from the blunting and re-sharpening of the fatigue crack tip were observed in the crack-propagation region. Based on these results, the damage and fracture mechanisms of the metallic glass induced by torsional loadings are elucidated.

  2. Fatigue damage and fracture behavior of tungsten fiber reinforced Zr-based metallic glassy composite

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Zhang, Z.F. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)]. E-mail: zhfzhang@imr.ac.cn; Wang, Z.G. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Qiu, K.Q. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Zhang, H.F. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Zang, Q.S. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Hu, Z.Q. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2006-02-25

    The fatigue life, damage and fracture behavior of tungsten fiber reinforced metallic glass Zr{sub 41.25}Ti{sub 13.75}Ni{sub 10}Cu{sub 12.5}Be{sub 22.5} composites are investigated under cyclic push-pull loading. It is found that the fatigue life of the composite increases with increasing the volume fraction of tungsten fibers. Similar to crystalline metals, the regions of crack initiation, propagation and overload fracture can be discerned on the fracture surface of the specimen. Fatigue crack normally initiates in the metallic glass matrix at the outer surface of the composite specimen and propagates predominantly in the matrix. Different crack front profile around the tungsten fibers and fiber pullout demonstrate that fatigue crack may propagate around the fiber, leading to bridging of the crack faces by the unbroken fiber and hence improved fatigue crack-growth resistance. Locally decreased effective stiffness in the region where fiber distribution is sparse may provide preferential crack path in the composite. A proposed model was exercised to elucidate different tungsten fiber fracture morphologies in the fatigue crack propagation and overload fracture regions in the light of Poisson's ratio effect during fatigue loading.

  3. Fatigue damage and fracture behavior of tungsten fiber reinforced Zr-based metallic glassy composite

    International Nuclear Information System (INIS)

    Zhang, H.; Zhang, Z.F.; Wang, Z.G.; Qiu, K.Q.; Zhang, H.F.; Zang, Q.S.; Hu, Z.Q.

    2006-01-01

    The fatigue life, damage and fracture behavior of tungsten fiber reinforced metallic glass Zr 41.25 Ti 13.75 Ni 10 Cu 12.5 Be 22.5 composites are investigated under cyclic push-pull loading. It is found that the fatigue life of the composite increases with increasing the volume fraction of tungsten fibers. Similar to crystalline metals, the regions of crack initiation, propagation and overload fracture can be discerned on the fracture surface of the specimen. Fatigue crack normally initiates in the metallic glass matrix at the outer surface of the composite specimen and propagates predominantly in the matrix. Different crack front profile around the tungsten fibers and fiber pullout demonstrate that fatigue crack may propagate around the fiber, leading to bridging of the crack faces by the unbroken fiber and hence improved fatigue crack-growth resistance. Locally decreased effective stiffness in the region where fiber distribution is sparse may provide preferential crack path in the composite. A proposed model was exercised to elucidate different tungsten fiber fracture morphologies in the fatigue crack propagation and overload fracture regions in the light of Poisson's ratio effect during fatigue loading

  4. Fracture strength of fiber-reinforced surface-retained anterior cantilever restorations

    NARCIS (Netherlands)

    Oezcan, Mutlu; Kumbuloglu, Ovul; User, Atilla

    2008-01-01

    Purpose: This study compared the fracture strength of direct anterior cantilever fiber-reinforced composite (FRC) fixed partial dentures (FPD) reinforced with 3 types of E-glass fibers preimpregnated with either urethane tetramethacrylate, bisphenol glycidylmethacrylate/polymethyl methacrylate, or

  5. Enhanced fatigue endurance of metallic glasses through a staircase-like fracture mechanism.

    Science.gov (United States)

    Gludovatz, Bernd; Demetriou, Marios D; Floyd, Michael; Hohenwarter, Anton; Johnson, William L; Ritchie, Robert O

    2013-11-12

    Bulk-metallic glasses (BMGs) are now candidate materials for structural applications due to their exceptional strength and toughness. However, their fatigue resistance can be poor and inconsistent, severely limiting their potential as reliable structural materials. As fatigue limits are invariably governed by the local arrest of microscopically small cracks at microstructural features, the lack of microstructure in monolithic glasses, often coupled with other factors, such as the ease of crack formation in shear bands or a high susceptibility to corrosion, can lead to low fatigue limits (some ~1/20 of their tensile strengths) and highly variable fatigue lives. BMG-matrix composites can provide a solution here as their duplex microstructures can arrest shear bands at a second phase to prevent cracks from exceeding critical size; under these conditions, fatigue limits become comparable with those of crystalline alloys. Here, we report on a Pd-based glass that similarly has high fatigue resistance but without a second phase. This monolithic glass displays high intrinsic toughness from extensive shear-band proliferation with cavitation and cracking effectively obstructed. We find that this property can further promote fatigue resistance through extrinsic crack-tip shielding, a mechanism well known in crystalline metals but not previously reported in BMGs, whereby cyclically loaded cracks propagate in a highly "zig-zag" manner, creating a rough "staircase-like" profile. The resulting crack-surface contact (roughness-induced crack closure) elevates fatigue properties to those comparable to crystalline alloys, and the accompanying plasticity helps to reduce flaw sensitivity in the glass, thereby promoting structural reliability.

  6. Size-Dependent Brittle-to-Ductile Transition in Silica Glass Nanofibers.

    Science.gov (United States)

    Luo, Junhang; Wang, Jiangwei; Bitzek, Erik; Huang, Jian Yu; Zheng, He; Tong, Limin; Yang, Qing; Li, Ju; Mao, Scott X

    2016-01-13

    Silica (SiO2) glass, an essential material in human civilization, possesses excellent formability near its glass-transition temperature (Tg > 1100 °C). However, bulk SiO2 glass is very brittle at room temperature. Here we show a surprising brittle-to-ductile transition of SiO2 glass nanofibers at room temperature as its diameter reduces below 18 nm, accompanied by ultrahigh fracture strength. Large tensile plastic elongation up to 18% can be achieved at low strain rate. The unexpected ductility is due to a free surface affected zone in the nanofibers, with enhanced ionic mobility compared to the bulk that improves ductility by producing more bond-switching events per irreversible bond loss under tensile stress. Our discovery is fundamentally important for understanding the damage tolerance of small-scale amorphous structures.

  7. Fracture properties of hydrogenated amorphous silicon carbide thin films

    International Nuclear Information System (INIS)

    Matsuda, Y.; King, S.W.; Bielefeld, J.; Xu, J.; Dauskardt, R.H.

    2012-01-01

    The cohesive fracture properties of hydrogenated amorphous silicon carbide (a-SiC:H) thin films in moist environments are reported. Films with stoichiometric compositions (C/Si ≈ 1) exhibited a decreasing cohesive fracture energy with decreasing film density similar to other silica-based hybrid organic–inorganic films. However, lower density a-SiC:H films with non-stoichiometric compositions (C/Si ≈ 5) exhibited much higher cohesive fracture energy than the films with higher density stoichiometric compositions. One of the non-stoichiometric films exhibited fracture energy (∼9.5 J m −2 ) greater than that of dense silica glasses. The increased fracture energy was due to crack-tip plasticity, as demonstrated by significant pileup formation during nanoindentation and a fracture energy dependence on film thickness. The a-SiC:H films also exhibited a very low sensitivity to moisture-assisted cracking compared with other silica-based hybrid films. A new atomistic fracture model is presented to describe the observed moisture-assisted cracking in terms of the limited Si-O-Si suboxide bond formation that occurs in the films.

  8. Brittle-to-Ductile Transition in Metallic Glass Nanowires.

    Science.gov (United States)

    Şopu, D; Foroughi, A; Stoica, M; Eckert, J

    2016-07-13

    When reducing the size of metallic glass samples down to the nanoscale regime, experimental studies on the plasticity under uniaxial tension show a wide range of failure modes ranging from brittle to ductile ones. Simulations on the deformation behavior of nanoscaled metallic glasses report an unusual extended strain softening and are not able to reproduce the brittle-like fracture deformation as found in experiments. Using large-scale molecular dynamics simulations we provide an atomistic understanding of the deformation mechanisms of metallic glass nanowires and differentiate the extrinsic size effects and aspect ratio contribution to plasticity. A model for predicting the critical nanowire aspect ratio for the ductile-to-brittle transition is developed. Furthermore, the structure of brittle nanowires can be tuned to a softer phase characterized by a defective short-range order and an excess free volume upon systematic structural rejuvenation, leading to enhanced tensile ductility. The presented results shed light on the fundamental deformation mechanisms of nanoscaled metallic glasses and demarcate ductile and catastrophic failure.

  9. Mechanically driven phase separation and corresponding microhardness change in Cu60Zr20Ti20 bulk metallic glass

    DEFF Research Database (Denmark)

    Cao, Q.P.; Li, J.F.; Zhou, Y.H.

    2005-01-01

    Rolling deformation of bulk Cu60Zr20Ti20 metallic glass has been performed at cryogenic temperature. The specimens exhibit excellent ductility, and are rolled up to 97% reduction in thickness without fracture. Crystallization is suppressed during the deformation, however, phase separation is obse...... is observed in the glassy matrix when the thickness reduction exceeds 89%. Once the phase separation occurs, the microhardness of the specimen increases drastically, indicating the existence of work hardening by severe plastic deformation of the metallic glass.......Rolling deformation of bulk Cu60Zr20Ti20 metallic glass has been performed at cryogenic temperature. The specimens exhibit excellent ductility, and are rolled up to 97% reduction in thickness without fracture. Crystallization is suppressed during the deformation, however, phase separation...

  10. GRAN SASSO: Roman lead or physics experiments

    Energy Technology Data Exchange (ETDEWEB)

    Pascolini, Alessandro

    1991-09-15

    On June 15 at Oristano (Sardinia) a formal ceremony marked the start of an underwater archaeological campaign sponsored by the Istituto Nazionale di Fisica Nucleare (INFN) to recover the load of a Roman freighter (navis oneraria) which sank off Sardinia carrying an exceptionally large load of lead.

  11. Dwellers of the Sky: Serpent in the Greco-Roman Zodiac

    Directory of Open Access Journals (Sweden)

    dr.Wael Sayed Soliman

    2015-01-01

    Full Text Available The Ancient Egyptians were close observers of the heavenly bodies behavior from prehistoric times, which evidenced by the numerous astronomical tools and scenes they left. Throughout the Egyptian history, images of night sky decorated coffins, tombs, temples and some other different kinds of monuments. These images served as a theoretical and visual tribute to the solar cycle and bore strong renewing associations. This article investigates the function of the serpent within a various collection of ancient Egyptian zodiacs dating back to the Greco-Roman Period, which was readily incorporated into the existing tradition of astronomical iconography. In order to explain the adoption of the serpent, this article examines its role in the astronomical images. There are no actual evidences for serpent iconography found in ancient astronomical scenes before the Greco-Roman Period, I ample to prove that knowledge of those creatures existed from the earliest time, and pervade the Egyptian symbolism. The details of the serpent picture have sketched and valid for the Greco-Roman Egypt, starting from the Third Century B.C.

  12. 1st Roman Young Researchers Meeting Proceedings

    CERN Document Server

    Cannuccia, E; Pietrobon, D; Stellato, F; Veneziani, M

    2009-01-01

    During the last few decades scientists have been able to test the bases of the physics paradigms, where the quantum mechanics has to match the cosmological scales. Between the extremes of this scenario, biological phenomena and their complexity take place, challenging the laws we observe in the atomic and sub-atomic world. In order to explore the details of this world, new huge experimental facilities are under construction. These projects involve people coming from several countries and give physicists the opportunity to work together with chemists, biologists and other scientists. The Roman Young Researchers Meeting is a conference, organised by Ph. D. students and young postdocs connected to the Roman area. It is aimed primarily at graduate students and post-docs, working in physics. The 1st conference has been held on the 21st of July 2009 at the University of Roma Tor Vergata. It was organised in three sessions, devoted to Astrophysics and Cosmology, Soft and Condensed Matter Physics and Theoretical and ...

  13. Literacy and recitation in the Roman Empire

    Directory of Open Access Journals (Sweden)

    Letícia Fantin Vescovi

    2010-12-01

    Full Text Available In our modern societies, the paradigm of reading is individual and silent. However, far from being the only one possible, this wasn’t even the main form of reading in the Ancient times. The text doesn’t exist outside its materiality, and, if the current standard is the printed object, it was, for a long time, a form of transmission connected to practices of orality. In the Roman world, the main form of circulation of the literary text was the recitation, which happened in various ways: public or private recitations, literary contests where the text was judged from an oral performance, and even recitation when the text was been produced. We aim at observing the reading practices of the Roman society through poetic texts and at getting to know the reading protocols of that society at the moment when the maximum expansion of the written culture is achieved, i.e., the first and second centuries AD. 

  14. Wine vessels (Vasa vinaria in roman law

    Directory of Open Access Journals (Sweden)

    Aličić Samir

    2017-01-01

    Full Text Available The notion of 'wine vessels' in Roman law comprises all the winecontaining recipients. There is no legal standardization of wine vessels by means of volume, and although the terms amphora, urna and culleus are used to designate both the vessels and the units of measure, these are two different meanings of the terms. In regard of the question, whether the vessels make appurtenance of the wine, jurisprudents of proculean school divided them in two categories. In the first category are those that follow legal status of wine, usually amphoras and other jars (cadi which are used for 'packaging', i. e. 'bottling' of the wine. The second category make mostly vats (cuppae and ceramic cisterns (dolia, which don't follow legal status of wine, making instead part of farming equipment of a landed property (instrumentum fundi and it's appurtenance. But, the roman jurists are not consistent regarding criteria for distinguishing these two categories.

  15. Microstructure Effects on Spall Strength of Titanium-based Bulk Metallic Glass Composites

    Science.gov (United States)

    Diaz, Rene; Hofmann, Douglas; Thadhani, Naresh; Georgia Tech Team; GT-JPL Collaboration

    2017-06-01

    The spall strength of Ti-based metallic glass composites is investigated as a function of varying volume fractions (0-80%) of in-situ formed crystalline dendrites. With increasing dendrite content, the topology changes such that neither the harder glass nor the softer dendrites dominate the microstructure. Plate-impact experiments were performed using the 80-mm single-stage gas gun over impact stresses up to 18 GPa. VISAR interferometry was used to obtain rear free-surface velocity profiles revealing the velocity pullback spall failure signals. The spall strengths were higher than for Ti-6Al-4V alloy, and remained high up to impact stress. The influence of microstructure on the spall strength is indicated by the constants of the power law fit with the decompression strain rate. Differences in fracture behavior reveal void nucleation as a dominant mechanism affecting the spall strength. The microstructure with neither 100% glass nor with very high crystalline content, provides the most tortuous path for fracture and therefore highest spall strength. The results allow projection of spall strength predictions for design of in-situ formed metallic glass composites. ARO Grant # W911NF-09 ``1-0403 NASA JPL Contract # 1492033 ``Prime # NNN12AA01C; NSF GRFP Grant #DGE-1148903; and NDSE & G.

  16. Effect of phase transformation and partial crystallization on the mechanical properties of glass and glass-ceramics based on 3CaO.P_2O_5-SiO_2-MgO system

    International Nuclear Information System (INIS)

    Daguano, J.K.M.F.; Simba, B.G.; Santos, C.

    2011-01-01

    In this work, glass and glass-ceramics of the 3CaO.P_2O_5-SiO_2-MgO system were developed aiming to produce different crystallization degrees. Glasses were melted at 1600 deg C and heat treated at 700 deg C. Part of the glasses was crystallized using heat treatments at 770 deg C and 1150 deg C for 4h. The partial crystallization and phase transformations were responsible for different mechanical properties (bending strength, young modulus, fracture toughness and hardness) in each temperature. The mechanical response of the material is discussed in relation to the microstructure, crystalline phases, and porosity of the materials. (author)

  17. Glass/Ceramic Composites for Sealing Solid Oxide Fuel Cells

    Science.gov (United States)

    Bansal, Narottam P.; Choi, Sung R.

    2007-01-01

    A family of glass/ceramic composite materials has been investigated for use as sealants in planar solid oxide fuel cells. These materials are modified versions of a barium calcium aluminosilicate glass developed previously for the same purpose. The composition of the glass in mole percentages is 35BaO + 15CaO + 5Al2O3 + 10B2O3 + 35SiO2. The glass seal was found to be susceptible to cracking during thermal cycling of the fuel cells. The goal in formulating the glass/ ceramic composite materials was to (1) retain the physical and chemical advantages that led to the prior selection of the barium calcium aluminosilicate glass as the sealant while (2) increasing strength and fracture toughness so as to reduce the tendency toward cracking. Each of the composite formulations consists of the glass plus either of two ceramic reinforcements in a proportion between 0 and 30 mole percent. One of the ceramic reinforcements consists of alumina platelets; the other one consists of particles of yttria-stabilized zirconia wherein the yttria content is 3 mole percent (3YSZ). In preparation for experiments, panels of the glass/ceramic composites were hot-pressed and machined into test bars.

  18. Proposed method for determining the thickness of glass in solar collector panels

    Science.gov (United States)

    Moore, D. M.

    1980-01-01

    An analytical method was developed for determining the minimum thickness for simply supported, rectangular glass plates subjected to uniform normal pressure environmental loads such as wind, earthquake, snow, and deadweight. The method consists of comparing an analytical prediction of the stress in the glass panel to a glass breakage stress determined from fracture mechanics considerations. Based on extensive analysis using the nonlinear finite element structural analysis program ARGUS, design curves for the structural analysis of simply supported rectangular plates were developed. These curves yield the center deflection, center stress and corner stress as a function of a dimensionless parameter describing the load intensity. A method of estimating the glass breakage stress as a function of a specified failure rate, degree of glass temper, design life, load duration time, and panel size is also presented.

  19. Roman Travertine: proposed as a candidate for "Global Heritage Stone Resource" designation

    Science.gov (United States)

    Primavori, Piero

    2017-04-01

    Roman Travertine is one of the most long-standing and famous stones, used since the times of the Roman Empire. Together with Carrara and Botticino marbles, it is probably the most worldwide well-known and diffused Italian dimension stone. Travertine derives its name from the former town, known as Tibur in ancient Roman times; the ancient name for the stone was Lapis Tiburtinus, meaning Tibur Stone, which was gradually corrupted to Travertino (travertine). The Roman Travertine is geographically located circa 25 km to the east of Rome, Central Italy, in the hilly area of Guidonia-Montecelio and Tivoli. Its deposit, formed during late Pleistocene time over an active strike-slip fault nearby the Colli Albani quiescent volcano, is about 20 km2 wide and 60 m thick on average; the thickness is over 85 m toward its western N-S-elongated side, where thermal springs and large sinkholes occur in an aligned pattern. The first quarries date back to pre-Roman times; nowadays three main productive sub-zones can be recognized within the extractive basin: "Valle Pilella", "Barco" and "Le Fosse", where more than fifty quarries are in operation, together with a relevant number of processing plants and artisanal laboratories. Lithological and stratigraphical features allow the distinction of an extensive number of commercial varieties, being the most renowned the Classic, the Bianco, the Noce, the Paglierino, the Navona. Used since more than 2.500 years, the Roman Travertine has deeply characterized the architecture of Rome and its history, with the realization of villas, palaces, artistic and monumental buildings, and masterpieces with unmistakable features, such as the Anfiteatro Flavio (the Colosseum), the Theatre of Marcellus, the St. Peter's Basilica and Colonnade, the Tritone Fountain, the Adriana Villa, the Trevi Fountain, and many others. From Renaissance times on, the travertine has been extensively used to build an innumerable amount of churches, common buildings and houses

  20. Early Roman military fortifications and the origin of Trieste, Italy.

    Science.gov (United States)

    Bernardini, Federico; Vinci, Giacomo; Horvat, Jana; De Min, Angelo; Forte, Emanuele; Furlani, Stefano; Lenaz, Davide; Pipan, Michele; Zhao, Wenke; Sgambati, Alessandro; Potleca, Michele; Micheli, Roberto; Fragiacomo, Andrea; Tuniz, Claudio

    2015-03-31

    An interdisciplinary study of the archaeological landscape of the Trieste area (northeastern Italy), mainly based on airborne light detection and ranging (LiDAR), ground penetrating radar (GPR), and archaeological surveys, has led to the discovery of an early Roman fortification system, composed of a big central camp (San Rocco) flanked by two minor forts. The most ancient archaeological findings, including a Greco-Italic amphora rim produced in Latium or Campania, provide a relative chronology for the first installation of the structures between the end of the third century B.C. and the first decades of the second century B.C. whereas other materials, such as Lamboglia 2 amphorae and a military footwear hobnail (type D of Alesia), indicate that they maintained a strategic role at least up to the mid first century B.C. According to archaeological data and literary sources, the sites were probably established in connection with the Roman conquest of the Istria peninsula in 178-177 B.C. They were in use, perhaps not continuously, at least until the foundation of Tergeste, the ancestor of Trieste, in the mid first century B.C. The San Rocco site, with its exceptional size and imposing fortifications, is the main known Roman evidence of the Trieste area during this phase and could correspond to the location of the first settlement of Tergeste preceding the colony foundation. This hypothesis would also be supported by literary sources that describe it as a phrourion (Strabo, V, 1, 9, C 215), a term used by ancient writers to designate the fortifications of the Roman army.

  1. Dynamic fracture initiation in brittle materials under combined mode I/II loading

    International Nuclear Information System (INIS)

    Nakano, M.; Kishida, K.; Yamauchi, Y.; Sogabe, Y.

    1994-01-01

    A new test method has been developed to measure the resistance of dynamic fracture initiation in brittle materials under combined mode I/II loadings. The Brazilian disks with center-cracks have been fractured under oblique impact loadings in diametral-compression. The dynamic stress intensity factors of mode I and II are evaluated from the superposition integrals of the step response functions for the cracked disk. The experimental results are presented to elucidate the influence of loading rate on the combined mode fracture toughness for ceramics and glasses. (orig.)

  2. Greek and roman calendars

    CERN Document Server

    Hannah, Robert

    2005-01-01

    The smooth functioning of an ordered society depends on the possession of a means of regularising its activities over time. That means is a calendar, and its regularity is a function of how well it models the more or less regular movements of the celestial bodies - of the moon, the sun or the stars. Greek and Roman Calendars examines the ancient calendar as just such a time-piece, whose elements are readily described in astronomical and mathematical terms. The story of these calendars is one of a continuous struggle to maintain a correspondence with the regularity of the seasons and the sun, d

  3. Fracture Resistance of Endodontically Treated Teeth Restored with Biodentine, Resin Modified GIC and Hybrid Composite Resin as a Core Material.

    Science.gov (United States)

    Subash, Dayalan; Shoba, Krishnamma; Aman, Shibu; Bharkavi, Srinivasan Kumar Indu; Nimmi, Vijayan; Abhilash, Radhakrishnan

    2017-09-01

    The restoration of a severely damaged tooth usually needs a post and core as a part of treatment procedure to provide a corono - radicular stabilization. Biodentine is a class of dental material which possess high mechanical properties with excellent biocompatibility and bioactive behaviour. The sealing ability coupled with optimum physical properties could make Biodentine an excellent option as a core material. The aim of the study was to determine the fracture resistance of Biodentine as a core material in comparison with resin modified glass ionomer and composite resin. Freshly extracted 30 human permanent maxillary central incisors were selected. After endodontic treatment followed by post space preparation and luting of Glass fibre post (Reforpost, Angelus), the samples were divided in to three groups based on the type of core material. The core build-up used in Group I was Biodentine (Septodont, France), Group II was Resin-Modified Glass Ionomer Cement (GC, Japan) and Group III was Hybrid Composite Resin (TeEconom plus, Ivoclar vivadent). The specimens were subjected to fracture toughness using Universal testing machine (1474, Zwick/Roell, Germany) and results were compared using One-way analysis of variance with Tukey's Post hoc test. The results showed that there was significant difference between groups in terms of fracture load. Also, composite resin exhibited highest mean fracture load (1039.9 N), whereas teeth restored with Biodentine demonstrated the lowest mean fracture load (176.66 N). Resin modified glass ionomer exhibited intermediate fracture load (612.07 N). The primary mode of failure in Group I and Group II was favourable (100%) while unfavourable fracture was seen in Group III (30%). Biodentine, does not satisfy the requirements to be used as an ideal core material. The uses of RMGIC's as a core build-up material should be limited to non-stress bearing areas. Composite resin is still the best core build-up material owing to its high fracture

  4. EBSD and EDS of nickel sulfide inclusions in glass

    International Nuclear Information System (INIS)

    Miflin, G.E.; Barry, J.C.

    2002-01-01

    Full text: A delayed phase transformation in small nickel sulfide inclusions can cause spontaneous fracture in toughened glass. Typically, a phase transformation within a 5 ?g nickel sulphide inclusion may break a window which weighs more than 50 kg. In most cases the nickel sulfide inclusions are detected only after window failure, although it is possible to detect the inclusions within intact glass. It is known that only type three nickel sulphide inclusions, that is, inclusions with a composition in the range Ni 7 S 6 to NiS 1.03 , break the glass. The solid-state phase transformation of alpha Ni 1-x S to beta NiS which induces a 2.5% volume increase has been given as the main reason for the spontaneous fracture. The aim of this present study is to investigate the crystal structure of phases within the type three inclusions using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). With EBSD it is possible to map regions of alpha Ni 1-x S and to distinguish those regions from regions with beta Ni 1-x S when the elemental compositions of the two regions are identical. The inclusions of this study came from two sources. One set of inclusions were found at initiation-of-fracture in glass windows that had failed by spontaneous fracture, while the other set were found in intact windows. All of the inclusions came from windows on buildings in the Brisbane area. The EBSD analysis was done at 20kV with the stage tilted to 70 degrees on a Philips XL30 SEM with LaB 6 filament, and with attached Oxford/Link Opal camera and software. EBSD mapping was done for alpha nickel sulfide (Ni 1-x S), beta nickel sulphide (NiS), heazelwoodite (Ni 3 S 2 ), and godlevskite (Ni 9 S 8 ). The integration time was 1.3 seconds for each point. Colour coded crystal phase and grain orientation maps were produced. EDS analysis was also done on the Philips XL30 with attached EDAX EDS detector. We found that although the EBSD technique is successful in identifying alpha

  5. Interfacial fracture of the fibre-metal laminates based on fibre reinforced thermoplastics

    International Nuclear Information System (INIS)

    Abdullah, M.R.; Prawoto, Y.; Cantwell, W.J.

    2015-01-01

    As the adhesion quality plays an important role in determining the mechanical performance and environmental stability of most types of fibre-metal laminates (FMLs), investigating the interfacial fracture properties becomes one of the key factors for the improvement. Adhesion of a self-reinforced polypropylene (SRPP) and glass fibre reinforced polypropylene (GFPP) based FML is evaluated experimentally. Single Cantilever Beam (SCB) tests were performed to access interfacial fracture energy (G c ) of the bi-material laminates and their associated interlayer materials. Simulations mimicking the experiments were also performed. The energy needed to fracture was obtained experimentally and also via stress intensity factor from the simulations. The test results show that good adhesion between the aluminium and fibre reinforced thermoplastics can be achieved using a sulphuric acid anodising surface pre-treatment. Further examination has shown that the edges of the test samples highlighted the presence of significant fibre bridging in the SRPP and plastics deformation in the GFPP. - Highlights: • Adhesion of a self-reinforced polypropylene and glass fibre reinforced polypropylene is evaluated. • Single Cantilever Beam tests were performed to access interfacial fracture energy. • The energy needed to fracture was obtained experimentally and also via stress intensity factor from the simulations. • The test results show that best adhesion is achieved using a sulphuric acid anodizing surface pre-treatment

  6. Discovery of ancient Roman "highway" reveals geomorphic changes in karst environments during historic times.

    Science.gov (United States)

    Bernardini, Federico; Vinci, Giacomo; Forte, Emanuele; Furlani, Stefano; Pipan, Michele; Biolchi, Sara; De Min, Angelo; Fragiacomo, Andrea; Micheli, Roberto; Ventura, Paola; Tuniz, Claudio

    2018-01-01

    Sinkholes are a well-known geologic hazard but their past occurrence, useful for subsidence risk prediction, is difficult to define, especially for ancient historic times. Consequently, our knowledge about Holocene carbonate landscapes is often limited. A multidisciplinary study of Trieste Karst (Italy), close to early Roman military fortifications, led to the identification of possible ancient road tracks, cut by at least one sinkhole. Electrical Resistivity Tomography through the sinkhole has suggested the presence of a cave below its bottom, possibly responsible of the sinkhole formation, while Ground Penetrating Radar has detected no tectonic disturbances underneath the tracks. Additionally, archaeological surveys led to the discovery of over 200 Roman shoe hobnails within or close to the investigated route. According to these data, the tracks are interpreted as the remains of a main Roman road, whose itinerary has been reconstructed for more than 4 km together with other elements of ancient landscape. Our results provide the first known evidence of a Roman main road swallowed by sinkholes and suggest that Holocene karst landscapes could be much different from what previously believed. In fact, sinkholes visible nowadays in the investigated region could have been flat areas filled by sediments up to the Roman time.

  7. Wooden combs from the Roman fort at Vechten: the bodily appearance of soldiers

    NARCIS (Netherlands)

    Derks, A.M.J.; Vos, W.K.

    2010-01-01

    Abstract Excavations in the late 19th century and surveys carried out in the 1970s have produced 12 boxwood combs from the Roman fort at Vechten (NL). They are to be considered waste material that was dumped in the river Rhine which in the Roman period ran just north of the camp. In this article,

  8. The barbarians within. Illyrian colonists in roman Dacia

    Directory of Open Access Journals (Sweden)

    Irina NEMETI

    2011-03-01

    Full Text Available The present study attempts at grasping, as encompasing as possible, the process of acculturation undergone by peregrins from the Illyrian territories, a process that continued after their colonization in Dacia. The analysis follows the specific forms of organization of the various gentes arrived from Dalmatia (kastella, vicus, principes, noting the organized character of the colonization of these dalmatians, specialists in gold extraction. They were brought in compact groups and had their own institutions. The onomastic study took into consideration all persons who, through their names, relatives or origin, can be identified as illiri. Four groups of people have been identified, each illustrating a stage in their acculturation reflected in the onomastic system. In the field of religious life, one can note a continuous oscillation between the preservation of ancient values and the borrowing of new religious forms, which eventually lead to the colonized Illyrians assuming a new cultural identity. Learning Latin, acquiring Latin names, and adopting Roman gods indicates in historical terms their Romanization. In the funerary field, they were more conservative. As a funerary phenomenon, incineration with the deposition of calcined remains in ritually burnt pits is attributed to populations colonized in Dacia from the Dalmatian area. As for the inventory of their tombs and their funerary monuments on the other hand, one notes that they took over Roman material culture and used monuments that follow the canons of provincial art.

  9. The (in)visibility of the gods in the Greco-Roman world and of God in ...

    African Journals Online (AJOL)

    2015-10-26

    Oct 26, 2015 ... Greco-Roman world and in Hellenistic Judaism when reference was made to ..... Roman poet best known for the Metamorphoses, a 15-book continuous ...... W.A. Oldfather, Harvard University Press, Cambridge, MA, viewed 2.

  10. Physical properties of glasses exposed to Earth-facing and trailing-side environments on LDEF

    Science.gov (United States)

    Wiedlocher, David E.; Kinser, Donald L.; Weller, Robert A.; Weeks, Robert A.; Mendenhall, Marcus H.

    1993-01-01

    The exposure of 108 glass samples and 12 glass-ceramic samples to Earth-orbit environments permitted measurements which establish the effects of each environment. Examination of five glass types and one glass ceramic located on both the Earth-facing side and the trailing edge revealed no reduction in strength within experimental limits. Strength measurements subjected less than 5 percent of the sample surface area to stresses above 90 percent of the glass's failure strength. Seven micrometeorite or space debris impacts occurred on trailing edge samples. One of those impacts occurred in a location which was subjected to 50 percent of the applied stress at failure. Micrometeorite or space debris impacts were not observed on Earth-facing samples. The physical shape and structure of the impact sites were carefully examined using stereographic scanning electron microscopy. These impacts induce a stress concentration at the damaged region which influences mechanical strength. The flaw size produced by such damage was examined to determine the magnitude of strength degradation in micrometeorite or space-debris impacted glasses. Scanning electron microscopy revealed topographical details of impact sites which included central melt zones and glass fiber production. The overall crater structure is similar to much larger impacts of large meteorite on the Moon in that the melt crater is surrounded by shocked regions of material which fracture zones and spall areas. Residual stresses arising from shock compression and cooling of the fused zone cannot currently be included in fracture mechanics analyses based on simple flaw size examination.

  11. Scène de crime dans le roman policier : essai d’analyse lexico-syntaxique

    Directory of Open Access Journals (Sweden)

    Muryn Teresa

    2016-01-01

    Full Text Available Le présent article a pour but d’exposer l’analyse des structures rhétorico-lexico-syntaxiques propres au roman policier visant à établir la matrice lexico-syntaxique du genre en question. Le choix du roman policier résulte du fait que sa structure interne est stable indépendamment de l’auteur, de l’époque ou d’autres facteurs extérieurs. Ladite analyse, qui repose sur un corpus rassemblant des romans policiers en français et comptant actuellement 35850957 tokens, se situe sur deux niveaux : le premier concerne l’histoire elle-même, le second constitue l’échafaudage textuel de cette histoire. Elle consiste en extraction des structures RLS pertinentes pour les scènes normatives du genre; dans le cas du présent article pour la scène normative descriptive de la scène de crime dans le roman policier.

  12. Hydraulic fracturing in well ONM 15, Hassi-Messaoud field

    Energy Technology Data Exchange (ETDEWEB)

    Kerbouc, P

    1968-01-01

    In the Hassi-Messaoud field, hydraulic fracturing has been an extremely difficult problem because of the difficult conditions, and numerous tests run with conventional techniques which have had good results elswhere in the Sahara and worldwide, have given poor results. In Dec. 1967, the CFP(A) succeeded in an experimental fracturing operation on the ONM 15 well, increasing the production from 1 to 11 mU3D/hr. The principal results were: (1) in the sandstone reservoir of Hassi-Messaoud, the fracture was successfully propped with high-strength glass beads; (2) the orientation of the fracture was vertical; and (3) in certain favorable cases, such as wells that were mudded off or had a permeability barrier close to the well, the productivity can be increased by a factor of 10. However, it can still not be stated that hydraulic fracturing will be an economic stimulation method for the Hassi-Messaoud reservoir.

  13. Strength and Fractography of Glass Wool Fibres

    DEFF Research Database (Denmark)

    Lund, Majbritt Deichgræber; Yue, Yuanzheng

      Glass wool fibres (GWFs) are produced using the cascade spinning process. The lengths of the fibers range from 1 to 4 cm, whereas the diameters range from 4 and 10 mm. GWFs are widely used as insulation material due to their excellent heat and sound isolation effect, chemical durability, and high...... between fracture strength (sf) and mirror radius (r), i.e., sf = A*r, is confirmed for all the GWFs studied. The materials constant, A, (mirror constant) is found to be 2.4 ~ 2.7 MPam½ for basaltic wool and 2.0 MPam½ for E-glass wool, which is similar to the value reported in the literature for different...

  14. Fracture strengths of chair‑side‑generated veneers cemented with ...

    African Journals Online (AJOL)

    2014-06-09

    Jun 9, 2014 ... Group 1), CAD/CAM‑fabricated veneers cemented with a glass fiber ... specimens were tested with a universal testing machine after thermal cycling treatment. ... The purpose of the current in vitro study is to determine the ..... fracture resistance of fiber reinforced cups‑replacing composite restorations.

  15. Nets, Boats and Fishing in the Roman World

    DEFF Research Database (Denmark)

    Bekker-Nielsen, Tønnes

    2002-01-01

    Ithas been claimed that in Roman times, net fishing was a shore-based technology, but a study of literary sources and pictorial evidence, mainly mosaics, show that net fishing from boats was widespread throughout the first four centuries AD....

  16. Fracture mechanics of ceramics. Vol. 8. Microstructure, methods, design, and fatigue

    International Nuclear Information System (INIS)

    Bradt, R.C.; Evans, A.G.; Hasselman, D.P.H.; Lange, F.F.

    1986-01-01

    This paper presents information on the following topics: fracture mechanics and microstructures; non-lubricated sliding wear of Al 2 O 3 , PSZ and SiC; mixed-mode fracture of ceramics; some fracture properties of alumina-containing electrical porcelains; transformation toughening in the Al 2 O 3 -Cr 2 O 3 /ZrO 2 -HfO 2 system; strength toughness relationships for transformation toughened ceramics; tensile strength and notch sensitivity of Mg-PSZ; fracture mechanisms in lead zirconate titanate ceramics; loading-unloading techniques for determining fracture parameters of brittle materials utilizing four-point bend, chevron-notched specimens; application of the potential drop technique to the fracture mechanics of ceramics; ceramics-to-metal bonding from a fracture mechanics perspective; observed changes in fracture strength following laser irradiation and ion beam mixing of Ni overlayers on sintered alpha-SiC; crack growth in single-crystal silicon; a fracture mechanics and non-destructive evaluation investigation of the subcritical-fracture process in rock; slow crack growth in sintered silicon nitride; uniaxial tensile fatigue testing of sintered silicon carbide under cyclic temperature change; and effect of surface corrosion on glass fracture

  17. “Evaluation of fracture strength of teeth restored with different types ...

    African Journals Online (AJOL)

    Evaluation of fracture strength of teeth restored with different types of posts luted with different luting ... Nigerian Journal of Clinical Practice ... metal posts and glass‑fiber posts luted with resin‑based luting cement and glass ionomer cement.

  18. Using the discrete element method to simulate brittle fracture in the indentation of a silica glass with a blunt indenter

    International Nuclear Information System (INIS)

    Andre, Damien; Iordanoff, Ivan; Charles, Jean-luc; Jebahi, Mohamed; Neauport, Jerome

    2013-01-01

    The mechanical behavior of materials is usually simulated by a continuous mechanics approach. However, non-continuous phenomena such as multi-fracturing cannot be accurately simulated using a continuous description. The discrete element method (DEM) naturally accounts for discontinuities and is therefore a good alternative to the continuum approach. This work uses a discrete element model based on interaction given by 3D beam model. This model has proved to correctly simulate the elastic properties at the macroscopic scale. The simulation of brittle cracks is now tackled. This goal is attained by computing a failure criterion based on an equivalent hydrostatic stress. This microscopic criterion is then calibrated to fit experimental values of the macroscopic failure stress. Then, the simulation results are compared to experimental results of indentation tests in which a spherical indenter is used to load a silica glass, which is considered to be a perfectly brittle elastic material. (authors)

  19. Using glass-graded zirconia to increase delamination growth resistance in porcelain/zirconia dental structures.

    Science.gov (United States)

    Chai, Herzl; Mieleszko, Adam J; Chu, Stephen J; Zhang, Yu

    2018-01-01

    Porcelain fused to zirconia (PFZ) restorations are widely used in prosthetic dentistry. However, their tendency to delaminate along the P/Z interface remains a practical problem so that assessing and improving the interfacial strength are important design aspects. This work examines the effect of modifying the zirconia veneering surface with an in-house felspathic glass on the interfacial fracture resistance of fused P/Z. Three material systems are studied: porcelain fused to zirconia (control) and porcelain fused to glass-graded zirconia with and without the presence of a glass interlayer. The specimens were loaded in a four-point-bend fixture with the porcelain veneer in tension. The evolution of damage is followed with the aid of a video camera. The interfacial fracture energy G C was determined with the aid of a FEA, taking into account the stress shielding effects due to the presence of adjacent channel cracks. Similarly to a previous study on PFZ specimens, the fracture sequence consisted of unstable growth of channel cracks in the veneer followed by stable cracking along the P/Z interface. However, the value of GC for the graded zirconia was approximately 3 times that of the control zirconia, which is due to the good adhesion between porcelain and the glass network structure on the zirconia surface. Combined with its improved bonding to resin-based cements, increased resistance to surface damage and good esthetic quality, graded zirconia emerges as a viable material concept for dental restorations. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  20. Characterization of Boroaluminosilicate Glass Surface Structures by B k-edge NEXAFS

    Energy Technology Data Exchange (ETDEWEB)

    R Schaut; R Lobello; K Mueller; C Pantano

    2011-12-31

    Techniques traditionally used to characterize bulk glass structure (NMR, IR, etc.) have improved significantly, but none provide direct measurement of local atomic coordination of glass surface species. Here, we used Near-Edge X-ray Absorption Fine Structure (NEXAFS) as a direct measure of atomic structure at multicomponent glass surfaces. Focusing on the local chemical structure of boron, we address technique-related issues of calibration, quantification, and interactions of the beam with the material. We demonstrate that beam-induced adsorption and structural damage can occur within the timeframe of typical measurements. The technique is then applied to the study of various fracture surfaces where it is shown that adsorption and reaction of water with boroaluminosilicate glass surfaces induces structural changes in the local coordination of boron, favoring B{sup IV} species after reaction.

  1. A survey on orbital fractures in an educational center

    Directory of Open Access Journals (Sweden)

    Farahvash MR

    2009-06-01

    Full Text Available "n Normal 0 false false false EN-GB X-NONE AR-SA MicrosoftInternetExplorer4 st1":*{behavior:url(#ieooui } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;} Background: Trauma is the 2nd cause of mortality in Iran, after cardiovascular diseases. In traumatic patients, head and neck and face skeletal fracture is common. The most common facial fracture is mandible fracture and the least common is frontal fracture. Complications due to orbital fracture are more devasting than the other fractures in face."n"nMethods: These descriptive cross sectional studies are designed on 92 patients with orbital fractures in a referral educational trauma center, Imam Khomeini hospital, Tehran, Iran. Sample size was the patients who referred to this hospital with orbital fracture during the ten years period (1986-2000."n"nResults: In this study 74 patients were male and 18 patients were female. Mean age of patients was 30 years. The most common cause of orbital fracture was motor vehicle accident which was seen in 38 patients.46 patients had fracture in left orbit and 44 patients in right. Isolated orbital fracture was seen in 38 patients and 54 patients had concomitant trauma and fracture in the other organs. Management of orbital fracture was reduction of displaced bone fragment and fixation for osteosynthesis. The most common methods for osteosynthesis was

  2. Laser cutting sandwich structure glass-silicon-glass wafer with laser induced thermal-crack propagation

    Science.gov (United States)

    Cai, Yecheng; Wang, Maolu; Zhang, Hongzhi; Yang, Lijun; Fu, Xihong; Wang, Yang

    2017-08-01

    Silicon-glass devices are widely used in IC industry, MEMS and solar energy system because of their reliability and simplicity of the manufacturing process. With the trend toward the wafer level chip scale package (WLCSP) technology, the suitable dicing method of silicon-glass bonded structure wafer has become necessary. In this paper, a combined experimental and computational approach is undertaken to investigate the feasibility of cutting the sandwich structure glass-silicon-glass (SGS) wafer with laser induced thermal-crack propagation (LITP) method. A 1064 nm semiconductor laser cutting system with double laser beams which could simultaneously irradiate on the top and bottom of the sandwich structure wafer has been designed. A mathematical model for describing the physical process of the interaction between laser and SGS wafer, which consists of two surface heating sources and two volumetric heating sources, has been established. The temperature stress distribution are simulated by using finite element method (FEM) analysis software ABAQUS. The crack propagation process is analyzed by using the J-integral method. In the FEM model, a stationary planar crack is embedded in the wafer and the J-integral values around the crack front edge are determined using the FEM. A verification experiment under typical parameters is conducted and the crack propagation profile on the fracture surface is examined by the optical microscope and explained from the stress distribution and J-integral value.

  3. Frequency of Sports Trauma in Elite National Level Greco-Roman Wrestling Competitions

    OpenAIRE

    Akbarnejad, Ali; Sayyah, Mansour

    2012-01-01

    Background Trauma is an inescapable part of sports competitions. It occurs more frequently in contact sports such as wrestling. Objectives The purpose of this study was to determine the frequency of injury in Greco-Roman style wrestling competitions at national level. Patients and Methods This descriptive epidemiological research included 50 Greco-Roman style wrestlers who participated in national level competitions between the years 2003 and 2008. A questionnaire was completed by each partic...

  4. Female Aspirants to the Roman Catholic Priesthood.

    Science.gov (United States)

    Celmer, Virginia; Winer, Jane L.

    1990-01-01

    Investigated Holland vocational-personality types, job satisfaction, and psychological dysfunction among 85 parish priests, 55 nonparish priests, and 235 women who aspire to, but are barred from, ordination in the Roman Catholic Church. Found women's Holland-type code was most similar to code of clergy member as assigned by Dictionary of Holland…

  5. Miniplating of metacarpal fractures: an outcome study

    Directory of Open Access Journals (Sweden)

    Fallah E

    2011-05-01

    Full Text Available "n Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 st1":*{behavior:url(#ieooui } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;} Background: Trauma to the hand is very common and consequently, metacarpal fractures are not rare entities. Some of these fractures need surgery. Considering the diversity of surgical methods available for these kinds of fractures and also the importance of achieving full function and speedy return to work for patients that are mainly young workers or athletes, this study was undertaken to investigate the outcome of treating these fractures by mini-plates."n"nMethods : Eighteen patients with open or comminuted fractures of metacarpal bones who were admitted to the emergency department of Sina Hospital between the years 2007 and 2010 underwent fixation surgery using mini-plates. Fourteen patients with 17 metacarpal fractures completed the study."n"nResults : Thirteen out of 14 patients had complete fracture union. The patient with non-union underwent revision surgery and bone graft. Four individuals developed an extensor lag of 15 degrees without functional impairment. Two patients had joint stiffness that was relieved after a period of physiotherapy and one developed wound dehiscence and discharge that improved with debridement and use of antibiotics without plate removal. Six patients had

  6. Den historiske roman for børn

    DEFF Research Database (Denmark)

    Skyggebjerg, Anna Karlskov

    Bogen indeholder en redegørelse for den historiske roman som børnelitterær genre. Genren diskuteres i et teoretisk, historisk og analytisk perspektiv. Bogen afsluttes med en række principielle didaktiske overvejelser. Bogen er henvendt til alle, der beskæftiger sig professionelt med børnelitteratur...

  7. Tokoh Dan Penokohan Dalam Roman Panglipur Wuyung

    Directory of Open Access Journals (Sweden)

    Imam Budi Utomo

    2012-06-01

    Full Text Available Penelitian ini bertujuan untuk mengungkapkan model tokoh dan penokohan yang men­ jadi ciri umum dalam roman panglipur wuyung. Untuk itu, teori intrinsik yang mengkhususkan pa­da unsur tokoh dan penokohan digunakan untuk menganalisisnya. Dari hasil penelitian dapat di­ketahui bahwa sebagian besar tokoh dan penokohan dalam roman panglipur wuyung memiliki ti­pologi yang sama, yakni menampilkan tokoh berwatak datar (bersifat hitam­putih, tam­ pan/cantik, mengusung tokoh hero, dan lain­lain yang merupakan tokoh ideal dengan penggambaran yang klise. Abstract: This research aims to reveal the common feature of character and characterization models in the panglipur wuyung novelette. Therefore, the intrinsic theory specializing in characters and characterizations is used to analyze it. From the research result, it can be seen that most of the characters and characterizations in the panglipur wuyung novelette have the same typology, which shows flat character (black and white features handsome/beautiful, and carries the hero figures etc. which is an ideal figure of cliche depiction. Key Words: character and characterization, typology, panglipur wuyung novelette

  8. Roman capitals from Sirmium (Sremska Mitrovica, Serbia

    Directory of Open Access Journals (Sweden)

    Maver Andreja

    2009-01-01

    Full Text Available The article brings a detailed formal analysis of the Roman capitals from Sirmium, in the light of the stone analysis conducted on the material at the Museum of Srem and elsewhere in Sremska Mitrovica. The capitals dot the historical development of the town from the first half of the 2nd century until the 4th century. First made of regional limestone, they were later joined by those of limestone and marbles of distant source, whereby different stones in capitals coexisted almost throughout the town’s development. This was certainly the situation during the flourishing times of the late 3rd and the 4th century, when Sirmium, as one of the four capitals of the Roman Empire, stood within several formal circles of capitals. The plain-leaved capitals tie it to the rest of Pannonia, the Corinthianizing capitals to the provinces to the east and south, while part of the Asiatic capitals, the largest group, tie it to the wider area of the Mediterranean.

  9. Maritime trade contacts of Odisha, east coast of India with the Roman world: An appraisal

    Digital Repository Service at National Institute of Oceanography (India)

    Tripati, S.; Patnaik, S.K.; Pradhan, G.C.

    The present state of Odisha (previously known as Kalinga, Utkal,Odra and Orissa) lies on the east coast of India, and is known forits maritime contacts with the Roman world since the early histori-cal period, if not earlier. Initially, the Romans...

  10. Location of quarries of magnesian lime used as raw material of Roman plasters in western Lombardy (Italy

    Directory of Open Access Journals (Sweden)

    Roberto Bugini

    2017-01-01

    Full Text Available Lime as building material was widely diffused in Roman architecture of western Lombardy. The presence of magnesite (magnesium carbonate was detected in painted plasters coming from roman sites of Milano: magnesite indicates the use of dolomite to make the lime. Dolomite rocks widely outcrop in the Lombard Prealps: light grey dolomites and dolomitic limestones (Dolomia del Salvatore, Ladinian-Anisian; grey dolomites, sometimes with cyclothemes (Dolomia Principale, Norian. There is no evidence of Roman lime quarries or kilns in this area; the Romans probably exploited the same dolomite outcrops, located along the eastern shore of lake Maggiore, where lime was produced from the Middle Ages onwards. The glacio-fluvial deposits of the middle course of the river Adda (cobbles, pebbles of siliceous limestone together with limestone and dolomite outcropping in the river basin were another medieval and modern source of raw material, mainly to make a moderately hydraulic lime (called “calce forte”, but this kind of lime is lacking in Roman plasters.

  11. Incentive loss and hippocampal gene expression in inbred Roman high- (RHA-I) and Roman low- (RLA-I) avoidance rats.

    Science.gov (United States)

    Sabariego, Marta; Morón, Ignacio; Gómez, M José; Donaire, Rocío; Tobeña, Adolf; Fernández-Teruel, Alberto; Martínez-Conejero, José A; Esteban, Francisco J; Torres, Carmen

    2013-11-15

    Two recent microarray and qRT-PCR studies showed that inbred Roman high- (RHA-I, low anxiety and frustration vulnerability) and low-avoidance (RLA-I, high anxiety and frustration vulnerability) rats, psychogenetically selected on the basis of their divergence in two-way avoidance performance, differed in basal whole-brain and hippocampal expression of genes related to neurotransmission, emotion, stress, aversive learning, and drug seeking behavior. We have extended these studies by analyzing strain differences in hippocampal gene expression following a frustrative experience involving reward downshift, i.e. instrumental successive negative contrast (iSNC), a phenomenon in which the sudden reduction of an expected reward induces frustration/anxiety. Food-deprived male Roman rats were exposed to a reduction in the amount of solid food presented in the goal of a straight alley (from 12 pellets in "training" trials - i.e. preshift trials- to 2 pellets in "frustration testing" trials - i.e. postshift trials-). The iSNC effect, as measured by response latencies in the "postshift" trials, appeared only in RLA-I rats (i.e. higher response latencies in the 12-2 RLA-I group as compared to the 2-2 RLA-I control group in postshift trials). Two and a half hours after the "postshift" behavioral test, hippocampi were removed and stored (-80°C) until analysis. Microarray analysis of these hippocampi showed that four differentially-expressed, and qRT-PCR-validated genes (TAAR2, THAP1, PKD2L1, NANOS), have relevance for brain function and behavior, including schizophrenia, depression, anxiety, and drug addiction, thus showing the usefulness of Roman strains as a genetic model for research on the neurogenetic basis of frustration. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Tänavuse Roman Tavasti nimelise stipendiumi... / Kadri Mälk

    Index Scriptorium Estoniae

    Mälk, Kadri, 1958-

    2008-01-01

    2007. aasta Roman Tavasti nimelise stipendiumi pälvis Eesti Kunstiakadeemia ehtekunsti eriala üliõpilane Linda al-Assi, kes on sündinud Alzheerias, kasvanud Pärnus. Linda al-Assi ehteseeriast teemal "Andestus"

  13. Locating the timacum maius station on the roman road lissus-naissus-ratiaria: New archaeological research

    Directory of Open Access Journals (Sweden)

    Petrović Vladimir P.

    2008-01-01

    Full Text Available As the exact location of two Timacum stations remains an open issue, the results of the latest archaeological investigations in the environs of Svrljig, southeast Serbia, seem to offer some corroborative evidence for the hypothesis proposed in our previous contribution that this might be the location of Roman Timacum Maius. A small-scale trial excavation was undertaken on the Roman site at Kalnica in the Niševac village area in July 2008. A trench 4 by 2m was opened in the zone of the site that had yielded plentiful fragments of building debris as well as small finds. A massive wall over 1m thick was found immediately beneath the surface. Built of bro­ken limestone and pebbles bound with lime mortar, it obviously was part of a larger structure. To the northeast of the wall was an area covered with fragmented roof tiles. The discovery of two ceramic tumuli embedded in the wall, indicating a wall-heating system so far unregistered on the representative Roman urban and settlement sites in Serbia, gives additional grounds to presume that this was a larger Roman settlement extending over an area of more than 5ha, possibly Timacum Maius, a station on the Roman road Lissus-Ratiaria-Naissus.

  14. The plague under Marcus Aurelius and the decline and fall of the Roman Empire.

    Science.gov (United States)

    Fears, J Rufus

    2004-03-01

    The Roman Empire of the second century was a superpower that, in relative terms, dominated its world as much as the United States does today. In 166 AD, a plague broke out od pandemic proportions. The pandemic ravaged the entire extent of the Roman Empire, from its eastern frontiers in Iraq to its western frontiers on the Rhine River and Gaul, modern France, and western Germany. The disease is identified most often as smallpox, but it may have been anthrax. The study of bacterial DNA may enable identification of this plague that ravaged the Roman Empire at recurrent intervals for more than 100 years and that had a significant role in the decline and fall of this great superpower.

  15. Glass produced by underground nuclear explosions

    International Nuclear Information System (INIS)

    Schwartz, L.; Piwinskii, A.; Ryerson, F.; Tewes, H.; Beiriger, W.

    1983-01-01

    Detonation of an underground nuclear explosive produces a strong shock wave which propagates spherically outward, vaporizing the explosive and nearby rock and melting, the surrounding rock. The vaporized material expands adiabatically, forming a cavity. As the energy is dissipated during the cavity formation process, the explosive and rock debris condense and mix with the melted rock. The melt flows to the bottom of the cavity where it is quenched by fractured rock fragments falling from above as the cavity collapses. Measurements indicate that about 740 tonnes of rock and/or soil are melted for every kiloton (10 12 calories) of explosive energy, or about 25% of the explosive energy goes to melting rock. The resulting glass composition reflects the composition of the unaltered rock with explosive debris. The appearance ranges from white pumice to dense, dark lava. The bulk composition and color vary with the amount of explosive iron incorporated into the glass. The refractory explosion products are mixed with the solidified melt, although the degree of mixing is variable. Electron microprobe studies of glasses produced by Rainier in welded tuff have produced the following results: glasses are dehydrated relative to the host media, glasses are extremely heterogeneous on a 20 μm scale, a ubiquitous feature is the presence of dark marble-cake regions in the glass, which were locally enriched in iron and may be related to the debris, optically amorphous regions provide evidence of shock melting, only limited major element redistribution and homogenization occur within the cavity

  16. Resistance of Bonded Composite Restorations on Fractures of Endodontically Treated Teeth

    Directory of Open Access Journals (Sweden)

    AR Daneshkazemi

    2005-01-01

    Full Text Available Introduction: This study was performed to evaluate the effect of dentine bonding agents and Glass Ionomer cement beneath composite restorations and its resistance on fractures of endodontically treated teeth. Material and Methods: Forty sound maxillary teeth were selected; ten of them for positive control, and on the rest, RCT and MOD cavity preparations were done with standard methods. Then, the teeth were divided to four groups: 1-Sound teeth for positive control. 2-Prepared without any restoration for negative control. 3-Prepared and restored with Vitrabond(3M, USA, Single bond(3M, USA and Z100(3M, USA resin composite. 4-Prepared and restored by Single bond and Z100 resin composite. Specimens were subjected to compressive load by Instron 8502 until fracture occurred. Results: Group 1 showed the highest resistance to compressive forces followed by group 4,3&2 respectively. ANOVA, t test and Chi-square tests indicated significant difference between all the groups. Conclusion: Use of dentine bonding agents and resin composite increases resistance of endodontically treated teeth to fractures more than teeth restored with sandwich of glass ionomer cements, dentine bonding agents and resin composite.

  17. Archaeological and historical glasses: A bibliometric study

    Directory of Open Access Journals (Sweden)

    Villegas, M. A.

    2009-08-01

    Full Text Available Glass is one of the materials more widely developed throughout History. In the last decades, it has been stated a growing demand in the application of chemical-physical techniques to obtain more detailed information on technology and production of glasses in past societies. This research field lies within the domain of archaeometry. Results of a bibliometric study undertaken on 201 scientific articles published on ancient and historical glasses between 1987 and 2008 are presented in this paper. The study was carried out with the aim to address the evolution of glass archaeometric investigations in the last 20 years. Date of publication, journal and article types, topic, glass typology, analytical techniques, origin country of authors, and geographic location of samples were analyzed in this study, among other parameters. Resulting data indicate that archaeometric research on glasses has experienced an exponential growth in the period 2000-2008. Roman and Medieval glasses have been the materials more frequently investigated.

    El vidrio es uno de los materiales que más se ha utilizado a lo largo de la historia. En las últimas décadas se ha producido un aumento en la aplicación de técnicas químico-físicas para estudiar de forma más detallada la tecnología y producción de vidrio en las sociedades del pasado. Este tipo de investigación se encuadra en la disciplina conocida como Arqueometría. En este trabajo se ha realizado un estudio bibliométrico que abarca 201 artículos científicos sobre vidrio arqueológico e histórico publicados entre 1987 y 2008. El estudio se llevó a cabo con el objetivo de conocer la evolución de las investigaciones arqueométricas sobre vidrio en los últimos 21 años. Los parámetros analizados en este estudio bibliométrico fueron: fecha de publicación, tipo de revista y de artículo, tema, tipología del vidrio, técnicas analíticas, origen de los autores y localización geográfica de las

  18. The understanding of the R7T7 glass blocks long term behavior: chemical and transport coupling in fractured media; Comprehension de l'alteration a long terme des colis de verre R7T7: etude du couplage chimie transport dans un milieu fissure

    Energy Technology Data Exchange (ETDEWEB)

    Chomat, L

    2008-04-15

    The long term behavior of nuclear waste glass blocks depends highly on chemical reactions which occur at the surface in contact with water. Studies carried out on inactive fractured glass blocks show that fracture networks play a significant part in reactive surface area. Nevertheless, the complexity of results interpretation, due to a weak knowledge of fracture networks and local lixiviation conditions, does not allow us to comprehend the physical and chemical mechanisms involved. Model cracks are a key step to study chemical and transport coupling in fractured media. Crack lixiviation in aggressive conditions (pH{>=}11) show that the crack's position (horizontal or vertical) determines the dominant transport mechanism (respectively diffusion or convection induced by gravity). This gravity driven flow seems to be negligible in lower pH conditions. The convective velocity is estimated by a 1D model of reactive transport. Two other parameters are studied: the influence of thermal gradient and the influence of interconnected cracks on alteration. A strong retroactive effect of convection, due to thermal gradient, on the alteration kinetic is observed inside the crack. These works lead to a complete alteration experiment of a 163 crack network subject to a thermal gradient. The use of the geochemical software, HYTEC, within the framework of this study shows the potential of the software which is however limited by the kinetics law used. (author)

  19. The understanding of the R7T7 glass blocks long term behavior: chemical and transport coupling in fractured media; Comprehension de l'alteration a long terme des colis de verre R7T7: etude du couplage chimie transport dans un milieu fissure

    Energy Technology Data Exchange (ETDEWEB)

    Chomat, L

    2008-04-15

    The long term behavior of nuclear waste glass blocks depends highly on chemical reactions which occur at the surface in contact with water. Studies carried out on inactive fractured glass blocks show that fracture networks play a significant part in reactive surface area. Nevertheless, the complexity of results interpretation, due to a weak knowledge of fracture networks and local lixiviation conditions, does not allow us to comprehend the physical and chemical mechanisms involved. Model cracks are a key step to study chemical and transport coupling in fractured media. Crack lixiviation in aggressive conditions (pH{>=}11) show that the crack's position (horizontal or vertical) determines the dominant transport mechanism (respectively diffusion or convection induced by gravity). This gravity driven flow seems to be negligible in lower pH conditions. The convective velocity is estimated by a 1D model of reactive transport. Two other parameters are studied: the influence of thermal gradient and the influence of interconnected cracks on alteration. A strong retroactive effect of convection, due to thermal gradient, on the alteration kinetic is observed inside the crack. These works lead to a complete alteration experiment of a 163 crack network subject to a thermal gradient. The use of the geochemical software, HYTEC, within the framework of this study shows the potential of the software which is however limited by the kinetics law used. (author)

  20. Mas Gusó: a Roman military Settlement in the suburbium of Emporiae

    Directory of Open Access Journals (Sweden)

    Josep Casas Genover

    2016-11-01

    Full Text Available Although the site of Mas Gusó (province of Girona has been interpreted as a Roman uilla, this is actually a public building. Its existence have to be contextualized within the frame of the structures established by the Roman authority for territorial control closely linked to the creation of a new road network and a tax collection system. We also analyse its survival until the 3rd century AD, which are closely related to the nearby city of Emporiae.

  1. A Glass Ceramic Derived from High TiO2-Containing Slag – Microstructure Development and Mechanical Behaviour

    Czech Academy of Sciences Publication Activity Database

    Wu, J. P.; Rawlings, R. D.; Boccaccini, A. R.; Dlouhý, Ivo; Chlup, Zdeněk

    2006-01-01

    Roč. 89, č. 8 (2006), s. 2426-2433 ISSN 1551-2916 R&D Projects: GA ČR(CZ) GA106/06/0724; GA ČR(CZ) GA106/05/0495 Institutional research plan: CEZ:AV0Z20410507 Keywords : glass ceramic s * fracture toughness * flexural strength Subject RIV: JH - Ceramic s, Fire-Resistant Materials and Glass

  2. Sewerage system (cloaca) in Roman law

    OpenAIRE

    Aličić, Samir

    2012-01-01

    Sewerage system (cloaca), which implies any cavity through which waste water flows, has in Roman law a special legal protection due to its importance for public health preservation and safety of citizens. In Praetorian Edict, two interdicts are envisaged; one prohibitory, by which private sewerage system is protected and one restitutory, by which public sewerage system is protected. It is possible that a restitutory interdict about private sewerage system existed. By the public sewerage inter...

  3. Urban Life and Local Politics in Roman Bithynia

    DEFF Research Database (Denmark)

    Bekker-Nielsen, Tønnes

    Most studies of Roman local administration focus on the formal structures of power, as defined by imperial laws, urban institutions and magistracies. This book explores the interplay of formal power with informal factors such as social prejudice, parochialism and personal rivalries in the cities...

  4. Trade, Strategy and Communications on the Roman North-East Frontier

    DEFF Research Database (Denmark)

    Bekker-Nielsen, Tønnes

    2016-01-01

    The reorganisation of Pontos that Pompey carried out after defeating Mithradates VI Eupator has traditionally been seen as an example of enlightened Roman policy towards the provincials, which included the introduction of civic self-government and the promotion of commercial life. These goals...... Pompey attempted to achieve by establishing five urban communities along an existing east-west artery known as the “Pontic road”. A closer examination of the textual evidence and the actual remains of the “Pontic road”, however, indicate that the road had not been a trade route of any significance before...... the Roman conquest and that the motives behind Pompey’s dispositions were of a strategic, rather than a commercial, nature....

  5. Degradation of glass artifacts: application of modern surface analytical techniques.

    Science.gov (United States)

    Melcher, Michael; Wiesinger, Rita; Schreiner, Manfred

    2010-06-15

    A detailed understanding of the stability of glasses toward liquid or atmospheric attack is of considerable importance for preserving numerous objects of our cultural heritage. Glasses produced in the ancient periods (Egyptian, Greek, or Roman glasses), as well as modern glass, can be classified as soda-lime-silica glasses. In contrast, potash was used as a flux in medieval Northern Europe for the production of window panes for churches and cathedrals. The particular chemical composition of these potash-lime-silica glasses (low in silica and rich in alkali and alkaline earth components), in combination with increased levels of acidifying gases (such as SO(2), CO(2), NO(x), or O(3)) and airborne particulate matter in today's urban or industrial atmospheres, has resulted in severe degradation of important cultural relics, particularly over the last century. Rapid developments in the fields of microelectronics and computer sciences, however, have contributed to the development of a variety of nondestructive, surface analytical techniques for the scientific investigation and material characterization of these unique and valuable objects. These methods include scanning electron microscopy in combination with energy- or wavelength-dispersive spectrometry (SEM/EDX or SEM/WDX), secondary ion mass spectrometry (SIMS), and atomic force microscopy (AFM). In this Account, we address glass analysis and weathering mechanisms, exploring the possibilities (and limitations) of modern analytical techniques. Corrosion by liquid substances is well investigated in the glass literature. In a tremendous number of case studies, the basic reaction between aqueous solutions and the glass surfaces was identified as an ion-exchange reaction between hydrogen-bearing species of the attacking liquid and the alkali and alkaline earth ions in the glass, causing a depletion of the latter in the outermost surface layers. Although mechanistic analogies to liquid corrosion are obvious, atmospheric

  6. Les je gigognes du roman célinien

    Directory of Open Access Journals (Sweden)

    Gregor Perko

    2008-12-01

    Full Text Available Le présent article se penchera sur des aspects narratologiques des trois derniers romans de l’écrivain français Louis-Ferdinand Céline (1894–1961, d’un château l’autre (1957, nord (1960 et rigodon (publication posthume en 1964. Les romans, que la tradition critique solidement établie réunit en trilogie allemande,1 présentent l’aboutissement des recherches poétiques de l’écrivain tant au niveau du style qu’au niveau des techniques narratives. L’analyse qui s’appuiera pour l’essentiel sur le modèle narratologique de Gérard Genette (Genette 1972, 1983 se centrera sur différentes valeurs du je célinien :   –      je comme instance(s narrative(s, –      je comme foyer(s de perception, –      je comme personnage(s romanesque(s.

  7. Roman primacy and the development of the synodal institution in the period of the Arian controversy

    Directory of Open Access Journals (Sweden)

    Zakharov Georgii

    2015-01-01

    Full Text Available The object of this study is process of evolution of church organization in the 4th century, especially the relationships between Roman primacy and synodal institution in the epoch of the Arian controversy. The author examines evolution of the institution of the Roman synod and practice of participation of the Roman See in church councils outside Rome, focusing on the unsuccessful attempt to convene the general council in Rome in 382. Analysis of historical data shows that the ability of the Roman see to organize in a short time a representative council (mainly of the Italian bishops allowed Rome to claim for a special status within the church communion. In the same time the Roman See did not become in the 4th century the center of conciliar activity at the universal level. Participation of Rome in Ecumenical and Western councils was quite passive. In the second part of the paper the author attempts to reconstruct various models of church organization, which were typical for the western and the eastern episcopate in the 4th century. The author concludes that the real initiator of the development of universal primacy of Rome was not originally the pope, but the western episcopate (council of Serdica, 343. In the second part of the 4th century pope Damasus developed this conception, putting the principle of primacy of the Roman See as the chair of Peter above principle of synodal consensus. At the same time eastern bishops considered the Roman chair as the center of the West, rather than the head of the whole Church. Sometimes they invited bishop of Rome and other western bishops to act as arbiters in the eastern conflicts, but more often they defended the idea of full autonomy of the East.

  8. Fracturing of subterranean formations

    Energy Technology Data Exchange (ETDEWEB)

    Kiel, O.M.; Kidwell, A.L.

    1968-03-19

    This method of propping fractured formations results in high conductivities. In the method, certain naturally occurring crystals are used as propping agents. Suitable crystals include garnet, corundum, zircon, rutile, high-temperature quartz, and other minerals which have Moh's hardness values of about 6 or greater and weather out as individual crystals of about 40 mesh or larger. These are said to result in permeabilities significantly higher than those obtained with ordinary quartz sand, metallic shot, glass beads, plastic particles, walnut hulls, or similar materials. (10 claims)

  9. Effects of roughness on interfacial performances of silica glass and non-polar polyarylacetylene resin composites

    International Nuclear Information System (INIS)

    Jiang, Z.X.; Huang, Y.D.; Liu, L.; Long, J.

    2007-01-01

    The influence of roughness on interfacial performances of silica glass/polyarylacetylene resin composites was investigated. In order to obtain different roughness, silica glass surface was abraded by different grits of abrasives and its topography was observed by scanning electron microscopy and atomic force microscopy. At the same time, the failure mechanisms of composites were analyzed by fracture morphologies and the interfacial adhesion was evaluated by shear strength test. The results indicated that shear strength of silica glass/polyarylacetylene resin composites firstly increased and then decreased with the surface roughness of silica glass increased. The best surface roughness range of silica glass was 40-60 nm. The main mechanism for the improvement of the interfacial adhesion was physical interlocking at the interface

  10. Fracture toughness of fiber-reinforced glass ceramic and ceramic matrix composites

    Science.gov (United States)

    Stull, Kevin R.; Parvizi-Majidi, A.

    1991-01-01

    A fracture mechanics investigation of 2D woven Nicalon SiC/SiC and Nicalon SiC/LAS has been undertaken. An energy approach has been adopted to characterize and quantify the fracture properties of these materials. Chevron-notched bend specimens were tested in an edgewise configuration in which the crack propagated perpendicular to the ply direction. R-curves were obtained from repeated loading and unloading of specimens using several methods of data reduction. Values correconding to the plateau regions of the R-curves were taken as steady-state crack-growth resistance. These ranged from 37 to 63 kJ/sq m for 2D-SiC/LAS and 2.6 to 2.8 kJ/sq m for 2D-SiC/SiC composites.

  11. Deformation mechanism under essential work of fracture process in polycyclo-olefin materials

    Directory of Open Access Journals (Sweden)

    2008-06-01

    Full Text Available The fracture toughness of a glassy polycyclo-olefin (PCO was investigated by the essential work of fracture (EWF method using a double-edge notched specimens. It was shown that the PCO follows the EWF concept in the temperature range between room temperature and glass transition temperature Tg where the ligament yielding appear at a maximum point on the stress-displacement curves and subsequently the necking and tearing processes take place in the post yielding region. The essential work of fracture required for the ligament yielding drops as the temperature approaches Tg. The non-essential work of fracture attributed to tearing process after yielding is consumed to expand the plastic region and causes molecular chains to orient to the stretching direction.

  12. Roman Ways: The Endurance of Patterns in Travel and Hospitality from Antiquit

    Directory of Open Access Journals (Sweden)

    Bradford T. Hudson, Ph.D.

    2014-04-01

    Full Text Available Although it seems clear that multi-unit hotel and restaurant brands proliferated in the United States during the twentieth century, historical research demonstrates that the phenomenon is actually much older. The origins of hospitality chains can be traced back to the Roman Empire. Organizational systems and travel behaviors have remained remarkably similar throughout Western civilization during the past two millennia. The Roman relay station, the medieval post house, the New England inn, the railroad restaurant, and the highway hotel all share a common heritage.

  13. Remo cum fratre Quirinus: Metamorphoses of the Roman Foundation Myth from its Beginnings to Horace

    Directory of Open Access Journals (Sweden)

    Špela Tomažinčič

    2008-07-01

    Full Text Available From the first reference to Romulus by Alcimus, a historian from the mid-fourth century BC, where the hero appears alone, down to the age of Augustus, the story of the foundation of Rome underwent considerable plot changes. The two most important are, firstly, Romulus' later role not merely as a conditor urbis, but – in keeping with the Hellenistic tradition of ktiseis poleon – mainly as a creator gentis and a model of the new Roman, who can subsequently embody a new ethnic identity; and, secondly, the later dichotomy of the founders. The interpretation of the Roman foundation myth must be therefore closely associated with the symbolism of numbers – one founder as opposed to twin founders – as it is reflected in different socio-political and historical contexts. In addition to shaping society, myth also documents all its changes. In the context of replacing a single founder with twin founders, Romulus and Remus, the first critical change is the introduction of Remus. The twin founders imply a double community, a notion which becomes meaningful in Rome only after the plebeian achievement of political equality between 367 and 342 BC. The second significant change is the death of Remus, involving the notion of a foundation sacrifice, for which the evidence points to the crisis of 296 BC. The foundation story also serves as an explanation model for the events in the Late Roman Republic. Horace's pessimistic Seventh Epode evokes the foundation crime of fratricide to explain the tragic pattern of civil wars. As Romulus' successors, the Romans are also heirs to his crime, to the scelus fraternae necis, from which they cannot escape. Moreover, Romulus as a creator gentis represents a potential source for the Roman change of identity, which was regarded as coincidental with the foundation act. This recurring theme is elaborated first in Ennius' Annals and later in Vergil's Aeneid and Horace's Third ‘Roman Ode’. The central motif is Ennius

  14. Edith Wharton's "Roman Fever": A Rune of History.

    Science.gov (United States)

    Bauer, Dale M.

    1988-01-01

    Asserts that "Roman Fever" responds to a reactionary political climate, demonstrating an anti-reactionary thrust to Edith Wharton's fiction. Argues that Wharton deserves credit for articulating the destructive character of a cultural misogyny that led quickly to what she saw in 1933 as "a world whizzing ... crazily to the…

  15. Pouvoir et sexe : La favorita del Señor, roman de Ana Teresa Torres

    OpenAIRE

    Delprat, François

    2015-01-01

    La favorita del Señor (2001), roman de Ana Teresa Torres, se caractérise à la fois comme roman érotique et comme roman historique : la belle mauresque Aisa doit à une initiation précoce à l’art du sexe, dans son île natale méditerranéenne, d’accéder, devenue captive, à une exceptionnelle destinée en terre chrétienne. Éduquée par une esclave dans l’exultation des corps (danse érotique), elle est tour à tour bonne élève, adolescente passionnée, victime soumise et conquérante. La contradictoire ...

  16. Maxillary fractures: a review of 56 cases in a university affiliated hospital

    Directory of Open Access Journals (Sweden)

    Farahvash MR

    2009-07-01

    Full Text Available "n Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 st1":*{behavior:url(#ieooui } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;} Background: The aim of this study was to describe the prevalence of different types of maxillary fractures, concurrent fractures and accompanying signs and symptoms. Trauma is the second cause of mortality in Iran, after cardiovascular diseases. In traumatic patients, head, neck and facial bones fractures are common. The maxillary fractures are seen much less commonly than the fractures of the mandible, zygoma, or nose. Maxillary fractures include: (Le fort I, II, III fractures- alveolar process fracture and Sagittal fracture. The most common cause of maxillary fracture is motor vehicle accidents. "n"n Methods: This descriptive cross sectional study designed on 56 patients with maxillary fractures in a referral educational trauma center of Tehran. Sample size was the patients who referred to this hospital with maxillary fracture during past seven years. "n"nResults: Forty eight (86% patients were male and 8(14% were female. Male to female ratio was 6/1. Mean age of patients was 30 years. The most common type of maxillary fracture was infra orbital rim and floor fracture. Among Le fort fracture; Le fort type II was the most common. Paresthesia of infra orbital nerve and malocclusion were

  17. New radiocarbon data to study the history of roman and medieval Florence

    International Nuclear Information System (INIS)

    Arnoldus-Huyzendveld, A.; Fedi, M.E.; Cantini, F.; Bruttini, J.; Cartocci, A.; Calabrisotto, C. Scire

    2010-01-01

    Florence is a town worldwide known for its Renaissance masterpieces. It is often forgotten that it was founded during Roman times and remained a small village until the end of the early Middle Ages, practically confined within the ancient Roman boundaries. Since 2003, an extended archaeological research executed by the University of Sienna has studied the most ancient layers in the centre of Florence with the aim to enhance both the archaeological and paleo-environmental reconstruction of this area. One of the peculiarities of these excavations is that the early medieval layers were poor in datable ceramics, thus charcoals were sampled from different stratigraphic layers in order to contribute to the dating. Several data have already been published; here we focus on the excavation site of Palazzo Vecchio, now the seat of the municipality of Florence. This area is located close to the Arno river, along the eastern margin of the slightly elevated height upon which the Roman town was founded; actually, in the layers beneath the surface, the Roman theatre is still preserved. Radiocarbon dating of charcoals was performed in the LABEC laboratory in Florence, at the AMS beam line of the AMS-IBA 3 MV Tandetron accelerator. Comparison of these new data with the former ones and with the archaeological and geological data adds new information especially on natural phenomena like floods and on the human occupation of this area in the past.

  18. Insight on the glass-forming ability of Al–Y–Ni–Ce bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shih-Fan, E-mail: sfchen@ntut.edu.tw [Institute of Materials Science and Engineering, National Taipei University of Technology, Taipei 106, Taiwan (China); Chen, Chih-Yuan, E-mail: chen6563@gmail.com [Department of Energy Engineering, National United University, Miaoli 36003, Taiwan (China); Lin, Chia-Hung [Institute of Materials Science and Engineering, National Taipei University of Technology, Taipei 106, Taiwan (China)

    2015-07-15

    Highlights: • Adding 1 at.% cerium to Al{sub 87}Y{sub 8}Ni{sub 5} alloy causes glass transition. • A large ΔT{sub x} indicates that (Al{sub 87}Y{sub 8}Ni{sub 5}){sub 99}Ce{sub 1} is possibly a ductile amorphous alloy. • Ce is effective in improving the thermal stability of the Al–Y–Ni amorphous alloy. • The hardness of the crystallized cerium-bearing alloy was as high as 593 Hv. - Abstract: In the present study, the role of Ce in the thermal stability and glass forming ability (GFA) of (Al{sub 87}Y{sub 8}Ni{sub 5}){sub 99}Ce{sub 1} alloy ribbons produced by a single roller melt-spinning process has been investigated in an attempt to understand the influences of multiple RE elements in an Al–TM–RE (TM: transition metal, RE: rear earth metal) alloy system. Only the (Al{sub 87}Y{sub 8}Ni{sub 5}){sub 99}Ce{sub 1} alloy ribbon showed a glass transition temperature (T{sub g}) at 483.2 K, and its ΔT{sub x} value was 41.3 K. Crystallization occurred in the temperature range of 500–750 K in three exothermic reaction stages. The peak temperature for these reactions shifted toward higher temperatures at higher heating rates. XRD and SEM analysis of annealed samples revealed that nano-sized Al particles precipitated within the amorphous matrix during the first exothermic reaction. The maximum hardness was obtained for both non-cerium and cerium addition alloys after crystallization in the 550–660 K region due to numerous nano-sized precipitates randomly and homogeneously distributed in the amorphous matrix. Moreover, from observation of the fracture surface, it is found that the fracture mode transforms from ductile to brittle when the sample is annealed at a higher crystallization temperature, at which brittle intermetallic compounds appear.

  19. Relating 2-Rainbow Domination To Roman Domination

    Directory of Open Access Journals (Sweden)

    Alvarado José D.

    2017-11-01

    Full Text Available For a graph G, let R(G and yr2(G denote the Roman domination number of G and the 2-rainbow domination number of G, respectively. It is known that yr2(G ≤ R(G ≤ 3/2yr2(G. Fujita and Furuya [Difference between 2-rainbow domination and Roman domination in graphs, Discrete Appl. Math. 161 (2013 806-812] present some kind of characterization of the graphs G for which R(G − yr2(G = k for some integer k. Unfortunately, their result does not lead to an algorithm that allows to recognize these graphs efficiently. We show that for every fixed non-negative integer k, the recognition of the connected K4-free graphs G with yR(G − yr2(G = k is NP-hard, which implies that there is most likely no good characterization of these graphs. We characterize the graphs G such that yr2(H = yR(H for every induced subgraph H of G, and collect several properties of the graphs G with R(G = 3/2yr2(G.

  20. Roman concept of mental capacity to make end-of-life decisions.

    Science.gov (United States)

    Mendelson, Danuta

    2007-01-01

    When assessing decisional competence of patients, psychiatrists have to balance the patients' right to personal autonomy, their condition and wishes against principles of medical ethics and professional discretion. This article explores the age-old legal and ethical dilemmas posed by refusal of vital medical treatment by patients and their mental capacity to make end-of-life decisions against the background of philosophical, legal and medical approaches to these issues in the time of the Younger Pliny (c62-c113 CE). Classical Roman discourse regarding mental competency and "voluntary death" formed an important theme of the vast corpus of Greco-Roman writings, which was moulded not only by legal permissibility of suicide but also by philosophical (in modern terms, moral or ethical) considerations. Indeed, the legal and ethical issues of evaluating the acceptability of end of life decisions discussed in the Letters are as pertinent today as they were 2000 years ago. We may gain valuable insights about our own methodologies and frames of reference in this area of the law and psychiatry by examining Classical Roman approaches to evaluating acceptability of death-choices as described in Pliny's Letters and the writings of some of his peers.

  1. Processing glass-pyrochlore composites for nuclear waste encapsulation

    International Nuclear Information System (INIS)

    Pace, S.; Cannillo, V.; Wu, J.; Boccaccini, D.N.; Seglem, S.; Boccaccini, A.R.

    2005-01-01

    Glass matrix composites have been developed as alternative materials to immobilize nuclear solid waste, in particular actinides. These composites are made of soda borosilicate glass matrix, into which particles of lanthanum zirconate pyrochlore are encapsulated in concentrations of 30 vol.%. The fabrication process involves powder mixing followed by hot-pressing. At the relatively low processing temperature used (620 deg. C), the pyrochlore crystalline structure of the zirconate, which is relevant for containment of radioactive nuclei, remains unaltered. The microstructure of the composites exhibits a homogeneous distribution of isolated pyrochlore particles in the glass matrix and strong bonding at the matrix-particle interfaces. Hot-pressing was found to lead to high densification (95% th.d.) of the composite. The materials are characterized by relatively high elastic modulus, flexural strength, hardness and fracture toughness. A numerical approach using a microstructure-based finite element solver was used in order to investigate the mechanical properties of the composites

  2. Thermal phase stability of some simulated Defense waste glasses

    International Nuclear Information System (INIS)

    May, R.P.

    1981-04-01

    Three simulated defense waste glass compositions developed by Savannah River Laboratories were studied to determine viscosity and compositional effects on the comparative thermal phase stabilities of these glasses. The glass compositions are similar except that the 411 glasses are high in lithium and low in sodium compared to the 211 glass, and the T glasses are high in iron and low in aluminum compared to the C glass. Specimens of these glasses were heat treated using isothermal anneals as short as 10 min and up to 15 days over the temperature range of 450 0 C to 1100 0 C. Additionally, a specimen of each glass was cooled at a constant cooling rate of 7 0 C/hour from an 1100 0 C melt down to 500 0 C where it was removed from the furnace. The following were observed. The slow cooling rate of 7 0 C/hour is possible as a canister centerline cooling rate for large canisters. Accordingly, it is important to note that a short range diffusion mechanism like cooperative growth phenomena can result in extensive devitrification at lower temperatures and higher yields than a long-range diffusion mechanism can; and can do it without the growth of large crystals that can fracture the glass. Refractory oxides like CeO 2 and (Ni, Mn, Fe) 2 O 4 form very rapidly at higher temperatures than silicates and significant yields can be obtained at sufficiently high temperatures that settling of these dense phases becomes a major microstructural feature during slow cooling of some glasses. These annealing studies further show that below 500 0 C there is but little devitrification occurring implying that glass canisters stored at 300 0 C may be kinetically stable despite not being thermodynamically so

  3. Thermal phase stability of some simulated Defense waste glasses

    Energy Technology Data Exchange (ETDEWEB)

    May, R.P.

    1981-04-01

    Three simulated defense waste glass compositions developed by Savannah River Laboratories were studied to determine viscosity and compositional effects on the comparative thermal phase stabilities of these glasses. The glass compositions are similar except that the 411 glasses are high in lithium and low in sodium compared to the 211 glass, and the T glasses are high in iron and low in aluminum compared to the C glass. Specimens of these glasses were heat treated using isothermal anneals as short as 10 min and up to 15 days over the temperature range of 450/sup 0/C to 1100/sup 0/C. Additionally, a specimen of each glass was cooled at a constant cooling rate of 7/sup 0/C/hour from an 1100/sup 0/C melt down to 500/sup 0/C where it was removed from the furnace. The following were observed. The slow cooling rate of 7/sup 0/C/hour is possible as a canister centerline cooling rate for large canisters. Accordingly, it is important to note that a short range diffusion mechanism like cooperative growth phenomena can result in extensive devitrification at lower temperatures and higher yields than a long-range diffusion mechanism can; and can do it without the growth of large crystals that can fracture the glass. Refractory oxides like CeO/sub 2/ and (Ni, Mn, Fe)/sub 2/O/sub 4/ form very rapidly at higher temperatures than silicates and significant yields can be obtained at sufficiently high temperatures that settling of these dense phases becomes a major microstructural feature during slow cooling of some glasses. These annealing studies further show that below 500/sup 0/C there is but little devitrification occurring implying that glass canisters stored at 300/sup 0/C may be kinetically stable despite not being thermodynamically so.

  4. A multi-technique approach for the characterization of Roman mural paintings

    Energy Technology Data Exchange (ETDEWEB)

    Toschi, Francesco [CNR-IMIP (Istituto di Metodologie Inorganiche e dei Plasmi), Area della Ricerca Roma 1, Via Salaria Km. 29,300, 00016 Monterotondo, Roma, (Italy); Paladini, Alessandra, E-mail: alessandra.paladini@cnr.it [CNR-IMIP (Istituto di Metodologie Inorganiche e dei Plasmi), Area della Ricerca Roma 1, Via Salaria Km. 29,300, 00016 Monterotondo, Roma, (Italy); Colosi, Francesca [CNR-ITABC (Istituto per le Tecnologie Applicate ai Beni Culturali), Area della Ricerca Roma 1, Via Salaria Km. 29,300, 00016 Monterotondo, Roma (Italy); Cafarelli, Patrizia; Valentini, Veronica [CNR-IMIP (Istituto di Metodologie Inorganiche e dei Plasmi), Area della Ricerca Roma 1, Via Salaria Km. 29,300, 00016 Monterotondo, Roma, (Italy); Falconieri, Mauro; Gagliardi, Serena [ENEA, C.R. Casaccia, via Anguillarese 301, 00060 Roma (Italy); Santoro, Paola [CNR-ISMA (Istituto di Studi sul Mediterraneo Antico), Area della Ricerca Roma 1, Via Salaria Km. 29,300, 00016 Monterotondo, Roma (Italy)

    2013-11-01

    In the frame of an ongoing archeological study on the Sabina area, a countryside close to Rome, white and red samples of roman wall paintings have been investigated by combining X-ray diffraction and different spectroscopic methodologies, namely laser induced breakdown spectroscopy, μ-Raman and Fourier transform infrared attenuated total reflectance spectroscopy. The used multi-technique approach has allowed the unambiguous identification of the red pigment as red ochre and has provided insight on the provenance of both the pigment and the material used for the realization of the wall paintings. The experimental results have confirmed some assumptions on the use of local materials in roman rural architecture.

  5. Preliminary study in development of glass-ceramic based on SiO2-LiO2 system, starting of different SiO2 starting powders

    International Nuclear Information System (INIS)

    Daguano, J.K.M.F.; Santos, F.A.; Santos, C.; Marton, L.F.M.; Conte, R.A.; Rodrigues Junior, D.; Melo, F.C.L.

    2009-01-01

    In this work, lithium disilicate glass-ceramics were developed starting of the rice ash- SiO 2 and Li 2 CO 3 powders. The results were compared with glass ceramics based on the lithium disilicate obtained by commercial SiO 2 powders. Glass were melted at 1580 deg C, and annealed at 850 deg C. X-Ray diffraction and scanning electron microscopy were used for characterization of the materials, and hardness and fracture toughness were evaluated using Vickers indentation method. Glasses with amorphous structure were obtained in both materials. After annealing, 'rice-ash' samples presented Li 2 SiO 3 and residual SiO 2 as crystalline phases. On the other side, commercial SiO 2 - Samples presented only Li 2 Si 2 O 5 as crystalline phases and the better results of hardness and fracture toughness. (author)

  6. Intrinsic strength of sodium borosilicate glass fibers by using a two-point bending technique

    International Nuclear Information System (INIS)

    Nishikubo, Y; Yoshida, S; Sugawara, T; Matsuoka, J

    2011-01-01

    Flaws existing on glass surface can be divided into two types, extrinsic and intrinsic. Although the extrinsic flaws are generated during processing and using, the intrinsic flaws are regarded as structural defects which result from thermal fluctuation. It is known that the extrinsic flaws determine glass strength, but effects of the intrinsic flaws on the glass strength are still unclear. Since it is considered that the averaged bond-strength and the intrinsic flaw would affect the intrinsic strength, the intrinsic strength of glass surely depends on the glass composition. In this study, the intrinsic failure strain of the glass fibers with the compositions of 20Na 2 O-40xB 2 O 3 -(80-40x)SiO 2 (mol%, x = 0, 0.5, 1.0, 1.5) were measured by using a two-point bending technique. The failure strength was estimated from the failure strain and Young's modulus of glass. It is elucidated that two-point bending strength of glass fiber decreases with increasing B 2 O 3 content in glass. The effects of the glass composition on the intrinsic strength are discussed in terms of elastic and inelastic deformation behaviors prior to fracture.

  7. Interrogating Infanticide/ Child Euthanasia in the Roman Christian ...

    African Journals Online (AJOL)

    The purpose of this paper is an attempt to examine infanticide practices in the Roman Christian era and interrogate infanticide and child euthanasia in the same era. It also attempts to point out infanticide practices in Abuja and makes a distinction between infanticide and child euthanasia in Abuja. The study employed ...

  8. Microstructural dependence on relevant physical-mechanical properties on SiO2-Na2O-CaO-P2O5 biological glasses.

    Science.gov (United States)

    Rajendran, V; Begum, A Nishara; Azooz, M A; el Batal, F H

    2002-11-01

    Bioactive glasses of the system SiO2-Na2O-CaO-P2O5 have been prepared by the normal melting and annealing technique. The elastic moduli, attenuation, Vickers hardness, fracture toughness and fracture surface energy have been obtained using the known method at room temperature. The temperature dependence of elastic moduli and attenuation measurements have been extended over a wide range of temperature from 150 to 500 K. The SiO2 content dependence of velocities, attenuation, elastic moduli, and other parameters show an interesting observation at 45 wt% of SiO2 by exhibiting an anomalous behaviour. A linear relation is developed for Tg, which explores the influence of Na2O on SiO2-Na2O-CaO-P2O5 bioactive glasses. The measured hardness, fracture toughness and fracture surface energy show a linear relation with Young's modulus. It is also interesting to note that the observed results are functions of polymerisation and the number of non-bridging oxygens (NBO) prevailing in the network with change in SiO2 content. The temperature dependence of velocities, attenuation and elastic moduli show the existence of softening in the glass network structure as temperature increases.

  9. Reinforcing effect of glass-fiber mesh on complete dentures in a test model with a simulated oral mucosa.

    Science.gov (United States)

    Yu, Sang-Hui; Oh, Seunghan; Cho, Hye-Won; Bae, Ji-Myung

    2017-11-01

    Studies that evaluated the strength of complete dentures reinforced with glass-fiber mesh or metal mesh on a cast with a simulated oral mucosa are lacking. The purpose of this in vitro study was to compare the mechanical properties of maxillary complete dentures reinforced with glass-fiber mesh with those of metal mesh in a new test model, using a simulated oral mucosa. Complete dentures reinforced with 2 types of glass-fiber mesh, SES mesh (SES) and glass cloth (GC) and metal mesh (metal) were fabricated. Complete dentures without any reinforcement were prepared as a control (n=10). The complete dentures were located on a cast with a simulated oral mucosa, and a load was applied on the posterior artificial teeth bilaterally. The fracture load, elastic modulus, and toughness of a complete denture were measured using a universal testing machine at a crosshead speed of 5 mm/min. The fracture load and elastic modulus were analyzed using 1-way analysis of variance, and the toughness was analyzed with the Kruskal-Wallis test (α=.05). The Tukey multiple range test was used as a post hoc test. The fracture load and toughness of the SES group was significantly higher than that of the metal and control groups (P<.05) but not significantly different from that of the GC group. The elastic modulus of the metal group was significantly higher than that of the control group (P<.05), and no significant differences were observed in the SES and GC groups. Compared with the control group, the fracture load and toughness of the SES and GC groups were higher, while those of the metal group were not significantly different. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  10. Physical Properties of Fractured Porous Media

    Science.gov (United States)

    Mohammed, T. E.; Schmitt, D. R.

    2015-12-01

    The effect of fractures on the physical properties of porous media is of considerable interest to oil and gas exploration as well as enhanced geothermal systems and carbon capture and storage. This work represents an attempt to study the effect fractures have on multiple physical properties of rocks. An experimental technique to make simultaneous electric and ultrasonic measurements on cylindrical core plugs is developed. Aluminum end caps are mounted with ultrasonic transducers to transmit pules along the axis of the cylinder while non-polarizing electrodes are mounted on the sides of the core to make complex conductivity measurements perpendicular to the cylinder axis. Electrical measurements are made by applying a sinusoidal voltage across the measurement circuit that consist of a resister and the sample in series. The magnitude and phase of the signal across the sample is recorded relative to the input signal across a range of frequencies. Synthetic rock analogs are constructed using sintered glass beads with fractures imbedded in them. The fracture location, size and orientation are controlled and each fractured specimen has an unfractured counterpart. Porosity, Permeability, electrical conductivity and ultrasonic velocity measurements are conducted on each sample with the complex electrical conductivities recorded at frequencies from 10hz to 1 Mhz. These measurements allow us to examine the changes induced by these mesoscale fractures on the embedding porous medium. Of particular interest is the effect of fracture orientation on electrical conductivity of the rock. Seismic anisotropy caused by fractures is a well understood phenomenon with many rock physics models dedicated to its understanding. The effect of fractures on electrical conductivity is less well understood with electrical anisotropy scarcely investigated in the literature. None the less, using electrical conductivity to characterize fractures can add an extra constraint to characterization based

  11. Measuring the Contribution of Roman Catholic Secondary Schools to Students' Religious, Personal and Social Values

    Science.gov (United States)

    Village, Andrew; Francis, Leslie J.

    2016-01-01

    Roman Catholic schools have been part of the state-funded system of education in England and Wales since the 1850s. Currently, Roman Catholic schools provide places for around 10% of students attending state-maintained primary and secondary schools. The present study employed data collected during the 1990s to compare a range of religious, social,…

  12. Lime-pozzolana mortars in Roman catacombs: composition, structures and restoration

    International Nuclear Information System (INIS)

    Sanchez-Moral, Sergio; Luque, Luis; Canaveras, Juan-Carlos; Soler, Vicente; Garcia-Guinea, Javier; Aparicio, Alfredo

    2005-01-01

    Analyses of microsamples collected from Roman catacombs and samples of lime-pozzolana mortars hardened in the laboratory display higher contents in carbonated binder than other subaerial Roman monuments. The measured environmental data inside the Saint Callistus and Domitilla catacombs show a constant temperature of 15-17 deg C, a high CO 2 content (1700 to 3500 ppm) and a relative humidity close to 100%. These conditions and particularly the high CO 2 concentration speed-up the lime calcitization roughly by 500% and reduce the cationic diffusion to form hydrous calcium aluminosilicates. The structure of Roman catacomb mortars shows (i) coarser aggregates and thicker beds on the inside, (ii) thin, smoothed, light and fine-grained external surfaces with low content of aggregates and (iii) paintings and frescoes on the outside. The observed high porosity of the mortars can be attributed to cracking after drying linked with the high binder content. Hardened lime lumps inside the binder denote low water/mortar ratios for slaking. The aggregate tephra pyroclasts rich in aluminosilicate phases with accessorial amounts of Ba, Sr, Rb, Cu and Pb were analysed through X-ray diffraction (XRD), electron microprobe analysis (EMPA) and also by environmental scanning electron microscopy (ESEM) to identify the size and distribution of porosity. Results support procedures using local materials, special mortars and classic techniques for restoration purposes in hypogeal backgrounds

  13. The historiography of the Later Roman Empire: from maximal state to minimal state, and back again

    Directory of Open Access Journals (Sweden)

    Uiran Gebara da Silva

    2017-11-01

    Full Text Available The paper analyses the conceptual models of state used by the scholarship of the later Roman Empire. The argument here developed is that it is possible to identify an oscillation between opposing conceptions of state, sometimes maximalist, sometimes minimalist, and that such conceptions have almost always served as an explanatory structure of the later Roman Empire historical developments, with the greater or smaller size of that State seen alternately as the cause for either the disarticulation or maintenance of the Roman system in the Mediterranean. The paper presents an historical review of those conceptions, elaborates on their connections with the debate between modernism and primitivism in the ancient economy and deals with their structuring ideological assumptions and the almost ubiquitous presence of liberal ideological categories and assumptions (even among Marxist authors. The paper concludes by reflecting on how this historiographical opposition between minimalist and maximalist conceptions obscures our understanding of the class relations of the later Roman imperial system of government.

  14. Kerttu Wagner. Die historischen romane von Jaan Kross / Wolfgang Drechsler

    Index Scriptorium Estoniae

    Drechsler, Wolfgang, 1963-

    2001-01-01

    Arvustus: Wagner, Kerttu. Die historischen Romane von Jaan Kross : am Beispiel einer Untersuchung der deutschen und englischen Übersetzungen von "Professor Martensi ärasõit" (1984). Frankfurt am Main [etc.] : P. Lang, 2001.

  15. Mechanical stability of a Cm-doped celsian glass-ceramic

    International Nuclear Information System (INIS)

    Routbort, J.L.; Offermann, P.; Matzke, H.

    1983-01-01

    Radiation damage due to a α-decay of actinides will modify the material used to store nuclear wastes. For example, ionization-induced processes can fragment the oxide bonds of a glass thereby creating gas bubbles. Phase decomposition, swelling, and disordering of crystalline phases are other possibilities. The self-irradiation damage could also affect the fracture properties of the storage materials. Spontaneous failure and fragmentation of some brittle materials have been observed during storage. The fracture toughness, K/sub Ic/, of a material is of technological and scientific interest. The ease with which a material can be handled and transported depends partially on K/sub Ic/. The resistance to fracture caused by unavoidable thermoelastic stresses is determined by K/sub Ic/. Cracking may, in the presence of water, lead to accelerated material degradation since the amount of leaching is proportional to the available surface area under non-stagnant conditions. This is especially important when the storage time is expected to be very long. From a scientific viewpoint, K/sub Ic/ is a fundamental parameter which characterizes the stress intensity factor at the onset of rapid crack growth resulting in failure. The Hertzian indentation technique was used to measure the fracture properties of a celsian glass-ceramic (B1-3) developed for high-level waste storage. Spontaneous failure due to radiation was not observed, on the contrary, the self-radiation damage caused by recoiling Pu atoms resulting from α-decay of a Cm-244 doped sample to a dose of congruent to 1.5 x 10 19 α-decays/cm 3 increases K/sub Ic/ by at least 25%. This increase in toughness is probably caused by the internal stresses which result from disordering due to the radiation damage. This is confirmed by the broadening of the x-ray spectra as the result of self-radiation

  16. Effect of ion implantation on thermal shock resistance of magnesia and glass

    International Nuclear Information System (INIS)

    Gurarie, V.N.; Williams, J.S.; Watt, A.J.

    1995-01-01

    Monocrystals of magnesia together with glass samples have been subjected to ion implantation prior to thermal shock testing in an impulse plasma of continuously varied intensity. Measurements of the separation between fragments have been used to estimate the surface temperature. Fracture and deformation characteristics of the surface layer are measured in ion implanted and unimplanted samples using optical and scanning electron microscopy. Implantation-induced near-surface damage is analysed by ion channeling using 2 MeV He + ions. Ion implantation is shown to modify the near-surface structure of magnesia samples by introducing damage, which makes crack initiation easier under thermal stresses. The fracture threshold and maximum crack density are shifted towards the lower temperature range. Ion implanted MgO crystals show a ten fold increase in surface crack density. An increased crack density results in a decreased degree of damage characterised by the depth of crack penetration. The thermal stress resistance parameter of glass samples is increased at relatively small doses and decreased at higher doses. The results suggest that crack density and the degree of fracture damage in brittle ceramics operating under thermal shock conditions can be effectively controlled by ion implantation which provides crack initiating defects in the near-surface region. 23 refs., 7 figs

  17. A general mixed mode fracture mechanics test specimen: The DCB-specimen loaded with uneven bending moments

    DEFF Research Database (Denmark)

    Sørensen, Bent F.; Jørgensen, K.; Jacobsen, T.K.

    2004-01-01

    A mixed mode specimen is proposed for fracture mechanics characterisation of adhesive joints, laminates and multilayers. The specimen is a double cantilever beam specimen loaded with uneven bending moments at the two free beams. By varying the ratiobetween the two applied moments, the full mode...... glass-fibre laminates was studied. The mixed mode fracture resistance increased with increasing crack length due to fibre bridging, eventually reaching asteady-state level (R-curve behaviour). The steady-state fracture toughness level increased with increasing tangential crack opening displacement....

  18. Diffractive dijet search with Roman pots at CDF

    International Nuclear Information System (INIS)

    Melese, P.L.

    1996-08-01

    We present the results of a search for diffractive dijets produced in p anti p collisions at √s = 1.8 TeV from data collected by the Collider Detector at Fermilab using a Roman pot trigger. The dijet events exhibit additional diffractive characteristics such as rapidity gaps and boosted center-of-mass systems

  19. Effect of Si addition on glass-forming ability and mechanical properties of Cu-Zr-Al bulk metallic glass

    International Nuclear Information System (INIS)

    Malekan, M.; Shabestari, S.G.; Zhang, W.; Seyedein, S.H.; Gholamipour, R.; Makino, A.; Inoue, A.

    2010-01-01

    Research highlights: The Cu 50 Zr 43 Al 7 alloy has a surprising GFA, and the glassy rods with diameter of 10 mm have been produced in this research. It has not been reported that the Cu-based glassy rods (Cu ≥ 50 at.%) to be produced with the critical diameter greater than 10 mm. The novelty of this research is that the glass formation has been improved and the critical diameter increased to 12 mm for the alloy having x = 1 with the addition of Si. Different criteria are used to evaluate the influence of Si content on the GFA, and the possible mechanisms involved in the achievement of this GFA are also discussed. - Abstract: The effect of Si addition on the glass-forming ability (GFA) and mechanical properties of (Cu 50 Zr 43 Al 7 ) 100-x Si x (x = 0, 0.5, 1, 1.5 and 2 at.%) alloys were investigated. The GFA of Cu 50 Zr 43 Al 7 alloy is improved by addition of a small amount of Si, and the critical diameter for glass formation increases from 10 mm for the alloy with x = 0-12 mm for the alloy with x = 1 when prepared using copper mold casting. Different criteria are used to evaluate the influence of Si content on the GFA, and the possible mechanisms involved in the achievement of this GFA are also discussed. In the uniaxial compression, the bulk glassy alloys exhibit a limited plastic strain of less than 1%, but the compressive fracture strength and Young's modulus were obtained in high values of 1969-2129 MPa and 101-144 GPa, respectively. Fracture surface and shear bands of samples were studied by using scanning electron microscopy (SEM).

  20. Influence of subcritical crack growth on the determination of fracture toughness in brittle materials

    Czech Academy of Sciences Publication Activity Database

    Krautgasser, C.; Chlup, Zdeněk; Supancic, P.; Danzer, R.; Bermejo, R.

    2016-01-01

    Roč. 36, č. 5 (2016), s. 1307-1312 ISSN 0955-2219 Institutional support: RVO:68081723 Keywords : Fracture toughness * Environment * SCCG * Ceramics * Glass Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 3.411, year: 2016

  1. Electrophoretic deposition of mesoporous bioactive glass on glass-ceramic foam scaffolds for bone tissue engineering.

    Science.gov (United States)

    Fiorilli, Sonia; Baino, Francesco; Cauda, Valentina; Crepaldi, Marco; Vitale-Brovarone, Chiara; Demarchi, Danilo; Onida, Barbara

    2015-01-01

    In this work, the coating of 3-D foam-like glass-ceramic scaffolds with a bioactive mesoporous glass (MBG) was investigated. The starting scaffolds, based on a non-commercial silicate glass, were fabricated by the polymer sponge replica technique followed by sintering; then, electrophoretic deposition (EPD) was applied to deposit a MBG layer on the scaffold struts. EPD was also compared with other techniques (dipping and direct in situ gelation) and it was shown to lead to the most promising results. The scaffold pore structure was maintained after the MBG coating by EPD, as assessed by SEM and micro-CT. In vitro bioactivity of the scaffolds was assessed by immersion in simulated body fluid and subsequent evaluation of hydroxyapatite (HA) formation. The deposition of a MBG coating can be a smart strategy to impart bioactive properties to the scaffold, allowing the formation of nano-structured HA agglomerates within 48 h from immersion, which does not occur on uncoated scaffold surfaces. The mechanical properties of the scaffold do not vary after the EPD (compressive strength ~19 MPa, fracture energy ~1.2 × 10(6) J m(-3)) and suggest the suitability of the prepared highly bioactive constructs as bone tissue engineering implants for load-bearing applications.

  2. Sintered glass ceramic composites from vitrified municipal solid waste bottom ashes

    International Nuclear Information System (INIS)

    Aloisi, Mirko; Karamanov, Alexander; Taglieri, Giuliana; Ferrante, Fabiola; Pelino, Mario

    2006-01-01

    A glass ceramic composite was obtained by sinter-crystallisation of vitrified municipal solid waste bottom ashes with the addition of various percentages of alumina waste. The sintering was investigated by differential dilatometry and the crystallisation of the glass particles by differential thermal analysis. The crystalline phases produced by the thermal treatment were identified by X-ray diffraction analysis. The sintering process was found to be affected by the alumina addition and inhibited by the beginning of the crystal-phase precipitation. Scanning electron microscopy was performed on the fractured sintered samples to observe the effect of the sintering. Young's modulus and the mechanical strength of the sintered glass ceramic and composites were determined at different heating rates. The application of high heating rate and the addition of alumina powder improved the mechanical properties. Compared to the sintered glass ceramic without additives, the bending strength and the Young's modulus obtained at 20 deg. C/min, increased by about 20% and 30%, respectively

  3. Moses/Musaeus/Mochos and his God Yahweh, Iao, and Sabaoth, seen from a Graeco-Roman perspective

    NARCIS (Netherlands)

    van Kooten, G.H.; Kooten, G.H. van

    2006-01-01

    George H. van Kooten, “Moses/Musaeus/Mochos and His God Yahweh, Iao, and Sabaoth, Seen from a Graeco-Roman Perspective,” in The Revelation of the Name YHWH to Moses: Perspectives from Judaism, the Pagan Graeco-Roman World, and Early Christianity (ed. George H. van Kooten; Themes in Biblical

  4. The Roman Road System in the Golan: Highways, Paths and Tracks in Quotidian Life

    OpenAIRE

    Pažout Adam

    2017-01-01

    Roman Imperial Roads (highways) built, maintained and organized by the Roman army and provincial authorities were studied in the Golan Heights since Schumacher’s surveys in the 1880s. However, most of these were obliterated by building and agricultural activity since the beginning of the 20th century. Local ancient road system, linking individual communities and their agricultural land was never studied, since it barely leaves a trace in archaeological record. This paper presents reconstructi...

  5. Morphologies of CaMoO sub 4 crystals in simulated nuclear waste disposal glass

    Energy Technology Data Exchange (ETDEWEB)

    Li, D.; Sengers, E.G.F.; Janssen, F.J.J.G. (KEMA, Arnhem (Netherlands). Chemical Technology and Material Research Dept.); Waal, H. de (TPO-TNO Glass Technology, Eindhoven (Netherlands))

    1992-07-01

    Fission products can diffuse through nuclear waste disposal glass due to the action of the temperature gradient caused by radioactive decay and the small thermal conductivity of the glass. Diffusion may eventually lead to crystallization. Because the densities of the products of glass crystallization may differ from that of the parent glass, crystallization causes stresses to develop, which can lead to fracture and exposure of increased surface area to environmental attack. Several kinds of crystals including, CaMoO{sub 4}, in the simulated nuclear waste disposal glass K{sub 3}, which consists of Na{sub 2}O, B{sub 2}O{sub 3}, SiO{sub 2} and other oxides, were identified previously after heat treatment. Recently it was found that CaMoO{sub 4} crystals have two kinds of morphologies in glass K{sub 3} heat-treated at temperatures between 870 and 1120 K. One kind of morphology, which is rather special, has not previously been reported. In this letter the morphologies of CaMoO{sub 4} crystals in this simulated nuclear waste disposal glass are discussed. (author).

  6. Lead sheathing of ship hulls in the Roman period: Archaeometallurgical characterisation

    Energy Technology Data Exchange (ETDEWEB)

    Kahanov, Yaacov, E-mail: yak@research.haifa.ac.il [Leon Recanati Institute for Maritime Studies, University of Haifa, Haifa 31905 (Israel); Ashkenazi, Dana [Faculty of Engineering, Tel Aviv University, Ramat Aviv 69978 (Israel)

    2011-08-15

    An archaeometallurgical analysis of samples of lead sheathing from five ships of the Roman period was carried out in order to determine their composition and microstructure, and to obtain a better understanding of their manufacturing processes. The examinations included optical microscopy of metallographic cross-sections, microhardness tests, scanning electron microscopy, including energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. The results show that the samples were all composed of lead covered with an oxide layer. The sheet thicknesses, microhardness values and microhardness distribution, as well as the grain size distribution, led to the conclusion that all of the sheets were produced by the same technology, using hammering, and were probably used for the same purpose. The presence of antimony was observed in the sample from the Roman ship from Caesarea, which may hint at an Italian (Sardinian) origin of the material, and perhaps of the ship. - Research Highlights: {yields} During the Roman period ship hulls were sheathed with lead. {yields} Five samples have been analysed for their characteristics and manufacturing process. {yields} The process was cold-working (strain-hardening) using hammering. {yields} The lead was open-casted on a flat stone, and later hammered at room temperature. {yields} Antimony in the Caesarea shipwreck may indicate an Italian origin of construction.

  7. Properties of Desert Sand and CMAS Glass

    Science.gov (United States)

    Bansal, Narottam P.; Choi, Sung R.

    2014-01-01

    As-received desert sand from a Middle East country has been characterized for its phase composition and thermal stability. X-ray diffraction analysis showed the presence of quartz (SiO2), calcite (CaCO3), gypsum (CaSO4.2H2O), and NaAlSi3O8 phases in as-received desert sand and showed weight loss of approx. 35 percent due to decomposition of CaCO3 and CaSO4.2H2O when heated to 1400 C. A batch of as-received desert sand was melted into calcium magnesium aluminosilicate (CMAS) glass at approx. 1500 C. From inductively coupled plasma-atomic emission spectrometry, chemical composition of the CMAS glass was analyzed to be 27.8CaO-4MgO-5Al2O3-61.6SiO2-0.6Fe2O3-1K2O (mole percent). Various physical, thermal and mechanical properties of the glass have been evaluated. Bulk density of CMAS glass was 2.69 g/cc, Young's modulus 92 GPa, Shear modulus 36 GPa, Poisson's ratio 0.28, dilatometric glass transition temperature (T (sub g)) 706 C, softening point (T (sub d)) 764 C, Vickers microhardness 6.3 +/- 0.4 GPa, indentation fracture toughness 0.75 +/- 0.15 MPa.m (sup 1/2), and coefficient of thermal expansion (CTE) 9.8 x 10 (exp -6)/degC in the temperature range 25 to 700 C. Temperature dependence of viscosity has also been estimated from various reference points of the CMAS glass using the Vogel-Fulcher-Tamman (VFT) equation. The glass remained amorphous after heat treating at 850 C for 10 hr but crystallized into CaSiO3 and Ca-Mg-Al silicate phases at 900 C or higher temperatures. Crystallization kinetics of the CMAS glass has also been investigated by differential thermal analysis (DTA). Activation energies for the crystallization of two different phases in the glass were calculated to be 403 and 483 kJ/mol, respectively.

  8. Ulpian's Appeal to Nature : Roman Law as Universal Law

    NARCIS (Netherlands)

    Brouwer, René

    2015-01-01

    In this paper I argue that against the political and perhaps even religiously motivated background of the Constitutio Antoniniana, in order to further enhance the appeal of Roman law, Ulpian seeks to connect law and nature by using Stoic terminology. However, his usage of this terminology is

  9. Effect of Al2O3 nano-filler on properties of glass-based seals for solid oxide fuel cells.

    Science.gov (United States)

    Lee, Dong Bok; Choi, Myong-Jae; Park, Sung; Lee, Jae Chun

    2013-01-01

    This study compares the viscosity and strength of three glass-based seals prepared with or without nano or micron-sized alumina powder used as filler material. Measurements of the viscosity and bending strength of the glass-based seals showed that addition of the nano-sized alumina powder to the glass increased both the high-temperature viscosity and the strength of the sintered glass matrix. Strength tests and observations of the microstructure of the fracture surface of the seal samples confirmed the strengthening of the glass network structure. Conversion of non-bridging oxygen to bridging oxygen is presumed to occur upon the addition of alumina to the glass sample. The strengthening of the alumina-glass composite seal was attributed to the alumina nano-filler and prolonged heat treatment at elevated temperatures.

  10. Face/core interface fracture characterization of mixed mode bending sandwich specimens

    DEFF Research Database (Denmark)

    Quispitupa, Amilcar; Berggreen, Christian; Carlsson, L.A.

    2011-01-01

    and PVC H45, H100 and H250 foam core materials were evaluated. A methodology to perform precracking on fracture specimens in order to achieve a sharp and representative crack front is outlined. The mixed mode loading was controlled in the mixed mode bending (MMB) test rig by changing the loading......Debonding of the core from the face sheets is a critical failure mode in sandwich structures. This paper presents an experimental study on face/core debond fracture of foam core sandwich specimens under a wide range of mixed mode loading conditions. Sandwich beams with E‐glass fibre face sheets...... application point (lever arm distance). Finite element analysis was performed to determine the mode‐mixity at the crack tip. The results showed that the face/core interface fracture toughness increased with increased mode II loading. Post failure analysis of the fractured specimens revealed that the crack...

  11. The Concept of ‘Due Performance’ (solutio of Civil Obligations in Classic Roman Law: Content and Scope

    Directory of Open Access Journals (Sweden)

    Paula Natalia Robles Bacca

    2016-12-01

    Full Text Available This article displays a chronological journey of some of the sources of Roman Law that allows us to establish the concept of the “due performance” in Rome. To this extent, we proceed to a reflection of the modifications and adjustments occurred regarding the concept of solutio, during archaic and classical Roman law. Therefore, we will focus on the exegetical study of some other Roman sources, which contains references to solutio, solvere and satisfactio, in order to establish through this path, the structural antecedent of the current notion of “due performance of obligations”.

  12. Marius and Trajan: Two Great Roman Strategists

    Science.gov (United States)

    1984-04-01

    soon respected as a good commander upon whom a soldier could count. His fairness of command is best demonstrated in an incident related by Plutarch ...to their discomfort and problems. (10:343) Plutarch also gave credit to Marius for altering the construction of the javelin. Marius replaced one of...Putnam’s Sons, 1927. 10. Plutarch (Translated by John Dryden, Revised by Arthur Hugh Clough). The Lives of the Noble Grecians and Romans. Chicago

  13. A double-voiced reading of Romans 13:1–7 in light of the imperial cult

    African Journals Online (AJOL)

    Drawing on Mikhail Bakhtin's theory of double-voicedness and James Scott's theory of public and hidden transcripts, this essay investigates the colonial context of Romans 13:1–7 with particular attention to the Roman imperial cult. It is my contention that Paul attempts to persuade the audience to resist the imperial cult, ...

  14. The nonagon as a tool for the drawing of the Roman Theatre of Lecce

    Directory of Open Access Journals (Sweden)

    Giampiero Mele

    2015-07-01

    Full Text Available  The signs of the Roman city of Lupiae, current Lecce, are many and among them the most noteworthy is the Roman Theatre. The monument has been accidentally discovered during the excavations for the foundations of a house in 1929  and it is located short distance from another landmark of the Roman Lecce: the amphitheatre. The chance of utilizing a the latest threedimensional technology for the detection of the  ruins was an opportunity to study the model of the survey obtained. The analysis of the latter reveals a mismatch with the instructions in “De Architectura” by Vitruvius and shows a particular use of the nonagon for the  design of its iconography. This study aims to compare the hypothesis obtained from the analysis of the metrological survey with the rules explained in the work of Vitruvio to underline similarities and differences between theory and practice.

  15. Tourist Valorization of Cultural Route “The Trail of the Roman Emperors“

    Directory of Open Access Journals (Sweden)

    Sanja Božić

    2013-01-01

    Full Text Available Cultural routes appear as a new concept that turned to be very beneficial in terms of the revitalization and presentation of cultural heritage in its broader sense - from archaeological sites to landscapes. These trails provide a unique purview into the spirit of modern countries and their inextricable connection to contemporary time. On the territory of present day Serbia 17 Roman emperors were born, which is one fifth and largest number of Roman emperors born anywhere in the world, outside of Rome. That was a good basis for developing idea of forming cultural route and starting the project „The Trail of the Roman Emperors“ in Serbia. It can be one of the most important topics in the field of cultural tourism in Serbia, and the main goal of this paper is to give a proposal for its valorization and promotion for the tourism purposes. This will be achieved through the evaluation of all elements of tourist valorization on the basis of which general tourist assessment will be formed, while the purpose of SWOT analysis was to detect existing strengths and weaknesses, and provide real opportunities and risks for this cultural route

  16. Strength on cut edge and ground edge glass beams with the failure analysis method

    Directory of Open Access Journals (Sweden)

    Stefano Agnetti

    2013-10-01

    Full Text Available The aim of this work is the study of the effect of the finishing of the edge of glass when it has a structural function. Experimental investigations carried out for glass specimens are presented. Various series of annealed glass beam were tested, with cut edge and with ground edge. The glass specimens are tested in four-point bending performing flaw detection on the tested specimens after failure, in order to determine glass strength. As a result, bending strength values are obtained for each specimen. Determining some physical parameter as the depth of the flaw and the mirror radius of the fracture, after the failure of a glass element, it could be possible to calculate the failure strength of that.The experimental results were analyzed with the LEFM theory and the glass strength was analyzed with a statistical study using two-parameter Weibull distribution fitting quite well the failure stress data. The results obtained constitute a validation of the theoretical models and show the influence of the edge processing on the failure strength of the glass. Furthermore, series with different sizes were tested in order to evaluate the size effect.

  17. Roman Catholic Church and media in information age

    Directory of Open Access Journals (Sweden)

    Kyyak Maksym Tarasovich

    2013-11-01

    Full Text Available Roman Catholic Church in the modern information age extensively exploits opportunities of traditional and new media. It has always been trying to be a dynamic and successive participant in the global information space. However, the media has become not only the most important attribute of the information society but also one of the most valuable instruments of religious authority.

  18. Medications and their use in the Graeco-Roman era

    Directory of Open Access Journals (Sweden)

    François Retief

    2007-09-01

    Full Text Available As from the 6th century BC Graeco-Roman medical therapy comprised three components, viz. diet and healthy lifestyle (regimen, surgery and medicaments (pharmacotherapy, of which the latter was the oldest. Although the Corpus Hippocraticum (5th century BC, with minor Egyptian influence, contained no text of medicines as such, and seemed to prefer regimen to medicaments, it nevertheless laid the foundation for the empirical use of pharmacotherapy (free of superstition and magic for the next millennium. The first Greek herbal was produced by Diocles in the 4th century BC, when the botanist Theophrastus also wrote his classic works on plants which contained a significant contribution on herbal medicines. The Alexandrian Medical School systematized and expanded Hippocratic medicine, and Herophilus introduced compound preparations. The concept that medicaments cure illness by restoring the bodily balance of humours and primary properties was largely perpetuated, but new views on physiology were gradually emerging. Unfortunately the bulk of original contributions from Hellenistic doctors are lost to posterity and only known to us through the writings of for example Celsus and Galen in Roman times. The interesting history of theriac, the so-called universal antidote, is reviewed. In the 1st century Dioscorides produced his Materia Medica which remained an authoritative pharmacopoeia up to modern times. Galen’s empiric views on pharmacotherapy (2nd century, still largely based on Hippocrates, became dogma in Medieval times, but mysticism and superstition gradually swept back into medicine. Retrospectively it is clear that with the exception of certain analgesics and narcotics like opium, Graeco-Roman medicaments were pharmacologically inert (even toxic and obtained positive results largely through a placebo effect.

  19. Properties of discontinuous S2-glass fiber-particulate-reinforced resin composites with two different fiber length distributions.

    Science.gov (United States)

    Huang, Qiting; Garoushi, Sufyan; Lin, Zhengmei; He, Jingwei; Qin, Wei; Liu, Fang; Vallittu, Pekka Kalevi; Lassila, Lippo Veli Juhana

    2017-10-01

    To investigate the reinforcing efficiency and light curing properties of discontinuous S2-glass fiber-particulate reinforced resin composite and to examine length distribution of discontinuous S2-glass fibers after a mixing process into resin composite. Experimental S2-glass fiber-particulate reinforced resin composites were prepared by mixing 10wt% of discontinuous S2-glass fibers, which had been manually cut into two different lengths (1.5 and 3.0mm), with various weight ratios of dimethacrylate based resin matrix and silaned BaAlSiO 2 filler particulates. The resin composite made with 25wt% of UDMA/SR833s resin system and 75wt% of silaned BaAlSiO 2 filler particulates was used as control composite which had similar composition as the commonly used resin composites. Flexural strength (FS), flexural modulus (FM) and work of fracture (WOF) were measured. Fractured specimens were observed by scanning electron microscopy. Double bond conversion (DC) and fiber length distribution were also studied. Reinforcement of resin composites with discontinuous S2-glass fibers can significantly increase the FS, FM and WOF of resin composites over the control. The fibers from the mixed resin composites showed great variation in final fiber length. The mean aspect ratio of experimental composites containing 62.5wt% of particulate fillers and 10wt% of 1.5 or 3.0mm cutting S2-glass fibers was 70 and 132, respectively. No difference was found in DC between resin composites containing S2-glass fibers with two different cutting lengths. Discontinuous S2-glass fibers can effectively reinforce the particulate-filled resin composite and thus may be potential to manufacture resin composites for high-stress bearing application. Copyright © 2017. Published by Elsevier Ltd.

  20. Eesti Maanteemuuseumis lavastub Roman Baskini käe all "Augustikuu teemaja"

    Index Scriptorium Estoniae

    Veski, Rivo

    2009-01-01

    Roman Baskini lavastatud komöödia "Augustikuu teemaja" Maanteemuuseumis. Autor John Patrick, mängivad mitmed harrastusteatrite näitlejad, teiste hulgas MTÜ Vilde Teatri liikmed. Peaosas Marko Matvere

  1. Alteration of nuclear glass in contact with iron and claystone at 90 °C under anoxic conditions: Characterization of the alteration products after two years of interaction

    International Nuclear Information System (INIS)

    Schlegel, Michel L.; Martin, Christelle; Brucker, Florence; Bataillon, Christian; Blanc, Cécile; Chorro, Matthieu; Jollivet, Patrick

    2016-01-01

    The present study investigates the alteration of a fractured glass block in contact with iron and Callovo-Oxfordian claystone at 90 °C under anoxic and water-saturated conditions. The alteration rates and the nature of glass alteration products at the different compact interfaces (glass-clay, glass-iron) and in cracks were assessed by solution chemistry and microscopic-scale techniques (scanning electron microscopy coupled with energy-dispersive X-ray microscopy, microRaman spectroscopy, and X-ray absorption fine structure spectroscopy). A significant but modest (two-fold) increase in glass alteration in contact with steel was observed, leading to an average alteration rate over the experiment of about 0.007–0.014 g/m"2/d. This rate is significantly lower than forward rate r_0 in clay-equilibrated groundwater (1.7 g/m"2/d), indicating that a decrease of the alteration rate was not hindered by the steel presence. The corrosion–alteration interface was made up of successive layers of corrosion products in contact with iron, a layer of Fe silicates, and an altered glass layer enriched in Fe. Characterization of the glass block in direct contact with claystone revealed that the thickness of altered glass was much more important than at the glass-iron interface. The altered glass layer in contact with clay was slightly enriched in Fe and Mg, and depleted in alkali cations. Altered glass layers in cracks were usually limited to fringes thinner than 2 μm, with a thickness decreasing from the crack mouth, indicating that alteration is controlled by transport in the cracks. The fractures were partially filled with calcite and lanthanide hydroxocarbonate precipitates. These results contribute to the understanding of nuclear vitrified waste-iron-corrosion products interactions in a deep geological repository. - Highlights: • Anoxic alteration of glass in contact with iron and clay at 90 °C for two-years. • Alteration rates of 0.015 and 0.5 g/m"2/d at glass

  2. THE MAP OF ROMAN DACIA IN THE RECENT STUDIES

    Directory of Open Access Journals (Sweden)

    Szabo Csaba

    2014-04-01

    Full Text Available In this paper the author presents the evolution of the cartographic representation of Roman Dacia in the recent studies of archaeology and ancient history, focusing especially on the lacunas and main problems of foreign (non – Romanian maps, appeared in the last decade in the international scholarship.

  3. Factors influencing the shape of the fracture wave induced by the rod impact of a brittle material

    International Nuclear Information System (INIS)

    Resnyansky, A.D.; Bourne, N.K.

    2002-01-01

    A fracture wave in a brittle material is a continuous fracture zone which may be associated with the damage accumulation process during the propagation of shock waves. In multidimensional structures the fracture wave may behave in an unusual way. The high-speed photography of penetration of a borosilicate (pyrex) glass block by a hemispherical-nosed rod (1) shows a visible flat wave forming as the fracture front. The role of the complex stress state and kinetic description of the damage accumulation are analysed to describe the process of the impact. The DYNA2D hydrocode and a kinetic strain-rate sensitive model (2) are employed

  4. Drilling of optical glass with electroplated diamond tools

    Science.gov (United States)

    Wang, A. J.; Luan, C. G.; Yu, A. B.

    2010-10-01

    K9 optical glass drilling experiments were carried out. Bright nickel electroplated diamond tools with small slots and under heat treatment in different temperature were fabricated. Scan electro microscope was applied to analyze the wear of electroplated diamond tool. The material removal rate and grinding ratio were calculated. Machining quality was observed. Bond coating hardness was measured. The experimental results show that coolant is needed for the drilling processes of optical glasses. Heat treatment temperature of diamond tool has influence on wearability of diamond tool and grinding ratio. There were two wear types of electroplated diamond tool, diamond grit wear and bond wear. With the machining processes, wear of diamond grits included fracture, blunt and pull-out, and electroplated bond was gradually worn out. High material removal rates could be obtained by using diamond tool with suitable slot numbers. Bright nickel coating bond presents smallest grains and has better mechanical properties. Bright nickel electroplated diamond tool with slot structure and heat treatment under 200°C was suitable for optical glass drilling.

  5. Encapsulation of TRISO particle fuel in durable soda-lime-silicate glasses

    International Nuclear Information System (INIS)

    Heath, Paul G.; Corkhill, Claire L.; Stennett, Martin C.; Hand, Russell J.; Meyer, Willem C.H.M.; Hyatt, Neil C.

    2013-01-01

    Tri-Structural Isotropic (TRISO) coated particle-fuel is a key component in designs for future high temperature nuclear reactors. This study investigated the suitability of three soda lime silicate glass compositions, for the encapsulation of simulant TRISO particle fuel. A cold press and sinter (CPS) methodology was employed to produce TRISO particle–glass composites. Composites produced were determined to have an aqueous durability, fracture toughness and Vickers’ hardness comparable to glasses currently employed for the disposal of high level nuclear wastes. Sintering at 700 °C for 30 min was found to remove all interconnected porosity from the composite bodies and oxidation of the outer pyrolytic carbon layer during sintering was prevented by processing under a 5% H 2 /N 2 atmosphere. However, the outer pyrolytic carbon layer was not effectively wetted by the encapsulating glass matrix. The aqueous durability of the TRISO particle–glass composites was investigated using PCT and MCC-1 tests combined with geochemical modelling. It was found that durability was dependent on silicate and calcium solution saturation. This study provides significant advancements in the preparation of TRISO particle encapsulant waste forms. The potential for the use of non-borosilicate sintered glass composites for TRISO particle encapsulation has been confirmed, although further refinements are required

  6. Encapsulation of TRISO particle fuel in durable soda-lime-silicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Heath, Paul G.; Corkhill, Claire L.; Stennett, Martin C.; Hand, Russell J. [Immobilisation Science Laboratory, Department of Materials Science and Engineering, Robert Hadfield Building, University of Sheffield, Sheffield S1 3JD (United Kingdom); Meyer, Willem C.H.M. [Necsa, South African Nuclear Energy Corporation, PO Box 582, Pretoria, Gauteng (South Africa); Hyatt, Neil C., E-mail: n.c.hyatt@sheffield.ac.uk [Immobilisation Science Laboratory, Department of Materials Science and Engineering, Robert Hadfield Building, University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2013-05-15

    Tri-Structural Isotropic (TRISO) coated particle-fuel is a key component in designs for future high temperature nuclear reactors. This study investigated the suitability of three soda lime silicate glass compositions, for the encapsulation of simulant TRISO particle fuel. A cold press and sinter (CPS) methodology was employed to produce TRISO particle–glass composites. Composites produced were determined to have an aqueous durability, fracture toughness and Vickers’ hardness comparable to glasses currently employed for the disposal of high level nuclear wastes. Sintering at 700 °C for 30 min was found to remove all interconnected porosity from the composite bodies and oxidation of the outer pyrolytic carbon layer during sintering was prevented by processing under a 5% H{sub 2}/N{sub 2} atmosphere. However, the outer pyrolytic carbon layer was not effectively wetted by the encapsulating glass matrix. The aqueous durability of the TRISO particle–glass composites was investigated using PCT and MCC-1 tests combined with geochemical modelling. It was found that durability was dependent on silicate and calcium solution saturation. This study provides significant advancements in the preparation of TRISO particle encapsulant waste forms. The potential for the use of non-borosilicate sintered glass composites for TRISO particle encapsulation has been confirmed, although further refinements are required.

  7. [Interface bond and compatibility between GI-II glass/alumina composite and Vitadur alpha veneering porcelain].

    Science.gov (United States)

    Meng, Yukun; Chao, Yonglie; Liao, Yunmao

    2002-01-01

    Multiple layer techniques were commonly employed in fabricating all-ceramic restorations. Bond and compatibility between layers were vitally important for the clinical success of the restorations. The purposes of this study were to investigate the bond of the interface between the GI-II glass/alumina composite and Vitadur alpha veneering porcelain, and to study the thermal compatibility between them. Prepared a bar shaped specimen of GI-II glass/alumina composite 25 mm x 5 mm x 1 mm in size, with bottom surface pre-notched. The upper surface was veneered with Vitadur alpha veneering porcelain (0.2 mm opaque dentin and 0.6 mm dentin porcelain), then fractured and the fracture surface were examined under scanning electron microscope (SEM) and electron microprobe analyzer (EMPA) with electron beam of 10 micrometer in diameter; ten all-ceramic single crowns for an upper right central incisor were fabricated and the temperatures of thermal shock resistance were tested. SEM observation showed tight bond between the composite and the porcelain; The results of EMPA showed that penetration of Na, Al elements from glass/alumina into veneering porcelain and Si, K, Ca elements from veneering porcelain into glass/alumina occurred after sintering baking; The temperature of thermal shock resistance for anterior crowns in this study was 158 +/- 10.3 degrees C, cracks were mainly distributed in veneering porcelain with thicker layer. Chemical bond exists between the GI-II glass/alumina composite and Vitadur alpha veneering porcelain, and there is good thermal compatibility between them.

  8. Dynamic fracture and fragmentation patterns of borosilicate laminate glasses

    Directory of Open Access Journals (Sweden)

    Gómez del Río, T.

    2009-10-01

    Full Text Available The dynamic behaviour of laminate borosilicate glasses (BSG with polyvinylbutiral (PVB interfaces (0,38 mm located at different distances from the impact point have been studied and compared with monolithic glass. The mechanical behaviour under impact loads have been studied using a compression split Hopkinson pressure bar (SHPB. In these experiments, the stress-strain curves of the materials at high loading rates and the capability of transmitting and reflecting the impact energy have been determined. The influence of the position of the interface on the fragmentation statistics of the SHPB recovered fragments has also been considered and analysed according to the published theoretical models.

    En este trabajo se ha estudiado los comportamientos dinámicos de un vidrio monolítico de borosilicato y varios laminados de cristal de borosilicato (BSG con intercaras de polyvinylbutiral (PVB (0,38 mm situados a diferentes distancias respecto del punto de impacto. Los resultados de las diferentes configuraciones de laminados se han comparado con el vidrio monolítico. El comportamiento mecánico bajo cargas de impacto se han estudiado realizando ensayos de compresión con una barra Hopkinson (SHPB. A partir de estos experimentos se obtienen las curvas tensión-deformación de los materiales a altas velocidades de carga y su capacidad de transmitir y reflejar la energía del impacto. La influencia de la posición de la interfaz en las estadísticas de la fragmentación de los fragmentos recuperados también se ha considerado y analizado de acuerdo a los modelos teóricos publicados.

  9. Essential work of fracture analysis for starch filled poly(propylene carbonate) composites

    International Nuclear Information System (INIS)

    Wang, X.L.; Li, R.K.Y.; Cao, Y.X.; Meng, Y.Z.

    2007-01-01

    Starch filled poly(propylene carbonate) composites are environmental friendly materials. In this study, the fracture toughness of composites under mode I loading was determined by the essential work of fracture concept. The specific essential fracture work of the poly(propylene carbonate)/starch composites decreases with increasing the starch content, while the non-essential work term, βw p increases with increasing the starch content. In addition, the morphologies, thermal properties, thermo-mechanical properties were studied by scanning electron microscope, thermogravimetric analysis, dynamic mechanical analysis, and differential scanning calorimetry, respectively. The thermal and thermo-mechanical measurements revealed that increasing starch content led to an increase in glass transition temperature and thermal stability. Morphology observation indicates that poly(propylene carbonate) and starch have weak interfacial adhesion

  10. Nicole Krauss’un Aşkın Tarihi Adlı Romanında Tarihi İzlekler

    OpenAIRE

    KALAY, Faruk

    2014-01-01

    Modern edebiyatta önemli Yahudi Amerikan yazarlarından olan Nicole Krauss Yahuditoplumundaki yabancılaşma, yalnızlık ve göç konularına değinir. Başarılı romanı olanAşkın Tarihi II. Dünya Savaşı süresince Holokost’a maruz kalan ve etkilerini hissedenYahudi karakterle ilgilidir. Tarihle bütünleşen bu karakterler gerçek hayattakiinsanlardan ve olaylardan esinlenmiştir. Krauss romanında postmodern teknikleri dekullanır. Örneğin iç içe anlatım tekniği okuyucuya romanın kurgusal mı yoksa gerçek mio...

  11. The Wisdom of Youth: How Modern Ontario Roman Catholic Students Challenge and Resist the Persistent Colonial Agenda

    Science.gov (United States)

    Brennan, Terri-Lynn Kay

    2012-01-01

    Youth today in Roman Catholic schools are not experiencing the complete freedom of an identity that is unique and valued. They describe the Ontario Roman Catholic school system as if it is still an agent of colonial forces, maintaining imperial power through denominational religious elitism. Using a critical ethnographic methodology within a…

  12. Transfiguring the Dead: The Iconography, Commemorative Use, and Materiality of Mummy Shrouds from Roman Egypt

    OpenAIRE

    Jimenez, Lissette Marie

    2014-01-01

    The mummy shrouds, often overlooked or dissected into dichotomous parts because of their Hellenistic and Egyptian hybrid pictorial nature, provide unparalleled insight into religious and social facets of life and death in Roman Egypt. Moving beyond the aesthetic properties of these objects and focusing on the symbolic and material functions of the iconography on the shrouds enables a fuller understanding of individual and collective social aspirations of the inhabitants of Roman Egypt. When v...

  13. Face/core mixed mode debond fracture toughness characterization using the modified TSD test method

    DEFF Research Database (Denmark)

    Berggreen, Christian; Quispitupa, Amilcar; Costache, Andrei

    2014-01-01

    The modified tilted sandwich debond (TSD) test method is used to examine face/core debond fracture toughness of sandwich specimens with glass/polyester face sheets and PVC H45 and H100 foam cores over a large range of mode-mixities. The modification was achieved by reinforcing the loaded face sheet....... The fracture process was inspected visually during and after testing. For specimens with H45 core the crack propagated in the core. For specimens with an H100 core, the crack propagated between the resin-rich layer and the face sheet. © The Author(s) 2013 Reprints and permissions: sagepub...... with a steel bar, and fracture testing of the test specimens was conducted over a range of tilt angles. The fracture toughness exhibited mode-mixity phase angle dependence, especially for mode II dominated loadings; although, the fracture toughness remained quite constant for mode I dominated crack loadings...

  14. The Hellenistic Epigram and the Roman Poets of the Augustan Period

    Directory of Open Access Journals (Sweden)

    Jelena Isak Kres

    2010-07-01

    Full Text Available The paper surveys »Greece through Roman eyes« by searching individual Hellenistic literary epigrams for traces of their impact on the Augustan poets, especially on Vergil, but also on Horace, Propertius, Tibullus, and Ovid. The first section focuses on those passages which echo the poetry of the older generation of epigrammatists (4th—3rd century B.C., particularly Callimachus, Posidippus, and Asclepiades, and the second on those which allude to epigrams composed by the younger generation of Greek authors from the archaic and classical periods of Latin literature, such as Damagetus, Dioscorides, Philodemus, and Crinagoras. Besides the echoes of Greek poetry in the Roman poets’ passages, the paper examines in what ways and to what degree Roman history and Roman authors marked such Greek epigrammatists as Antipater of Sidon or Philip of Thessalonica. A key observation seems to be that Roman authors, albeit they may have written epigrams themselves, nevertheless preferred to embed fragments of epigrammatic poetry (or allusions to it in their longer works, as Vergil did in his Eclogues or the Aeneid. One way in which Vergil played on epigrammatic discourse was to include in the Aeneid recognisable motifs from the Hellenistic literary epigram (e.g. by Anyte and Damagetus, and to treat implicitly through these motifs, embedded in a new context, the same thematic problems as the model epigrams did. Another interesting observation is that the (supposed allusions do not refer exclusively to Greek epigrams but sometimes even to epigrammatic discourse within other poetry genres. An example is Vergil’s passage on Daphnis’ death in the Eclogues, which continues, and alludes to, Theocritus’ episode in the Idylls. While Theocritus’ passage on Daphnis’ death imitates the discourse of funerary epigrams in the voice of Thyrsis or Daphnis himself, Vergil’s passage actually contains a kind of rounded-off, spoken mythological epitaph. Later

  15. Machinability of lithium disilicate glass ceramic in in vitro dental diamond bur adjusting process.

    Science.gov (United States)

    Song, Xiao-Fei; Ren, Hai-Tao; Yin, Ling

    2016-01-01

    Esthetic high-strength lithium disilicate glass ceramics (LDGC) are used for monolithic crowns and bridges produced in dental CAD/CAM and oral adjusting processes, which machinability affects the restorative quality. A machinability study has been made in the simulated oral clinical machining of LDGC with a dental handpiece and diamond burs, regarding the diamond tool wear and chip control, machining forces and energy, surface finish and integrity. Machining forces, speeds and energy in in vitro dental adjusting of LDGC were measured by a high-speed data acquisition and force sensor system. Machined LDGC surfaces were assessed using three-dimensional non-contact chromatic confocal optical profilometry and scanning electron microscopy (SEM). Diamond bur morphology and LDGC chip shapes were also examined using SEM. Minimum tool wear but significant LDGC chip accumulations were found. Machining forces and energy significantly depended on machining conditions (pceramics (pceramics (pceramics. Surface roughness for machined LDGC was comparable for other glass ceramics. The removal mechanisms of LDGC were dominated by penetration-induced brittle fracture and shear-induced plastic deformation. Unlike most other glass ceramics, distinct intergranular and transgranular fractures of lithium disilicate crystals were found in LDGC. This research provides the fundamental data for dental clinicians on the machinability of LDGC in intraoral adjustments. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Effects of Shear Fracture on In-depth Profile Modification of Weak Gels

    Institute of Scientific and Technical Information of China (English)

    Li Xianjie; Song Xinwang; Yue Xiang'an; Hou Jirui; Fang Lichun; Zhang Huazhen

    2007-01-01

    Two sand packs were filled with fine glass beads and quartz sand respectively. The characteristics of crosslinked polymer flowing through the sand packs as well as the influence of shear fracture of porous media on the in-depth profile modification of the weak gel generated from the crosslinked polymer were investigated. The results indicated that under the dynamic condition crosslinking reaction happened in both sand packs,and the weak gels in these two cases became small gel particles after water flooding. The differences were:the dynamic gelation time in the quartz sand pack was longer than that in the glass bead pack. Residual resistance factor (FRR) caused by the weak gel in the quartz sand pack was smaller than that in the glass bead pack. The weak gel became gel particles after being scoured by subsequent flood water. A weak gel with uniform apparent viscosity and sealing characteristics was generated in every part of the glass bead pack,which could not only move deeply into the sand pack but also seal the high capacity channels again when it reached the deep part. The weak gel performed in-depth profile modification in the glass bead pack,while in the quartz sand pack,the weak gel was concentrated with 100 cm from the entrance of the sand pack. When propelled by the subsequent flood water,the weak gel could move towards the deep part of the sand pack but then became tiny gel particles and could not effectively seal the high capacity channels there. The in-depth profile modification of the weak gel was very weak in the quartz sand pack. It was the shear fracture of porous media that mainly affected the properties and weakened the in-depth profile modification of the weak gel.

  17. [Influence of La2O3 and Li2O on glass powder for infiltrating ZTA all-ceramic dental material formed by gel-casting].

    Science.gov (United States)

    Jin, Qiong; Wang, Xiao-fei; Yang, Zheng-yu; Tong, Yi-ping; Zhu, Li; Ma, Jian-feng

    2012-10-01

    The influence of La2O3 and Li2O on glass powder was studied in this paper, which is to infiltrate ZTA all-ceramic dental material formed by gel-casting. The performance of different component was analyzed to optimize glass formula. Six groups of glass powder were designed and prepared by conventional melt-quenching method. ZTA ceramic blocks were covered with glass paste, which were formed by gel-casting and sintered in 1200 degrees centigrade, then infiltrated in 1150 degrees centigrade for twice to make glass/ZTA ceramic composites. By detecting differential thermal analysis and melting range of infiltration glass power, as well as flexural strength, linear shrinkage, SEM and EDS of glass/ZTA ceramic composites, the optimized glass group was determined out. Statistical analysis was performed using SPSS 13.0 software package by means of paired t test or one way ANOVA. The bending strength of group Li1 was (291.2±27.9) MPa, significantly higher than group Li2 and group La2(Pglass of group Li1 can lubricate ZTA ceramics well, their structure was compact and had a few small pores. Intergranular fracture existed on cross surface as well as transgranular fracture. The results showed that Li1(30%La2O3-15%Al2O3-15%SiO2-15%B2O3-5%Li2O) glass infiltrated ZTA ceramic composite had the best capability. Glass/ZTA composite material can be prepared by gel-casting and infiltrating way, and this process is simple and economically suitable for general dental laboratory.

  18. Effect of Abrasion-Induced Contact Damage on the Optical Properties and Strength of Float Glass

    Science.gov (United States)

    2018-06-07

    in glass. J Am Ceram Soc. 1969;52(6):338–339. 2. Mecholsky JJ Jr, Freiman SW, Rice RW. Effect of grinding on flaw geometry and fracture of glass. J...Am Ceram Soc. 1977;60(3–4):114–117. 3. Rice RW, Mecholsky JJ Jr. The nature of strength controlling machining flaws in ceramics. In: Hockey BJ, Rice...National Bureau of Standards; 1979. p. 351–378. 4. Rice RW, Mecholsky JJ Jr, Becher PF. The effect of grinding direction on flaw character and

  19. Thermoplastic Micromodel Investigation of Two-Phase Flows in a Fractured Porous Medium

    Directory of Open Access Journals (Sweden)

    Shao-Yiu Hsu

    2017-01-01

    Full Text Available In the past few years, micromodels have become a useful tool for visualizing flow phenomena in porous media with pore structures, e.g., the multifluid dynamics in soils or rocks with fractures in natural geomaterials. Micromodels fabricated using glass or silicon substrates incur high material cost; in particular, the microfabrication-facility cost for making a glass or silicon-based micromold is usually high. This may be an obstacle for researchers investigating the two-phase-flow behavior of porous media. A rigid thermoplastic material is a preferable polymer material for microfluidic models because of its high resistance to infiltration and deformation. In this study, cyclic olefin copolymer (COC was selected as the substrate for the micromodel because of its excellent chemical, optical, and mechanical properties. A delicate micromodel with a complex pore geometry that represents a two-dimensional (2D cross-section profile of a fractured rock in a natural oil or groundwater reservoir was developed for two-phase-flow experiments. Using an optical visualization system, we visualized the flow behavior in the micromodel during the processes of imbibition and drainage. The results show that the flow resistance in the main channel (fracture with a large radius was higher than that in the surrounding area with small pore channels when the injection or extraction rates were low. When we increased the flow rates, the extraction efficiency of the water and oil in the mainstream channel (fracture did not increase monotonically because of the complex two-phase-flow dynamics. These findings provide a new mechanism of residual trapping in porous media.

  20. Astrology in Ancient Greek and Roman Culture

    Science.gov (United States)

    Campion, Nicholas

    2018-04-01

    This article deals with astrology in Greek and Roman culture. It considers astrology's theoretical background, technical basis, interpretative conventions, social functions, religious and political uses, and theory of fate, as well as critiques of it. Astrology is the name given to a series of diverse practices based in the idea that the stars, planets, and other celestial phenomena possess significance and meaning for events on Earth. It assumes a link between Earth and sky in which all existence—spiritual, psychological, and physical—is interconnected. Most premodern cultures practiced a form of astrology. A particularly complex variety of it evolved in Mesopotamia in the first and second millennia BCE from where it was imported into the Hellenistic world from the early 4th century BCE onward. There it became attached to three philosophical schools: those pioneered by Plato, Aristotle, and the Stoics, all of which shared the assumption that the cosmos is a single, living, integrated whole. Hellenistic astrology also drew on Egyptian temple culture, especially the belief that the soul could ascend to the stars. By the 1st century CE the belief in the close link between humanity and the stars had become democratized and diversified into a series of practices and schools of thought that ranged across Greek and Roman culture. It was practiced at the imperial court and in the street. It could be used to predict individual destiny, avert undesirable events, and arrange auspicious moments to launch new enterprises. It could advise on financial fortunes or the condition of one's soul. It was conceived of as natural science and justified by physical influences, or considered to be divination, concerned with communication with the gods and goddesses. In some versions the planets were neither influences nor causes of events on Earth, but timing devices, which indicated the ebb and flow of human affairs, like the hands on a modern clock. Astrology had a radical view of

  1. Looking for Colour on Greek and Roman Sculpture

    OpenAIRE

    Amanda Claridge

    2011-01-01

    Review of: Vinzenz Brinkmann, Oliver Primavesi, Max Hollein, (eds), Circumlitio. The Polychromy of Antique and Medieval Sculpture. Liebighaus Skulpturensammlung, Frankfurt am Main, 2010. New scientific methods now being applied to the analysis of traces of pigments and gilding on ancient Greek and Roman marble statuary, and other marble artefacts, have the potential to revolutionise our understanding of the relationship between form and colour in antiquity. At present the enquiry is still...

  2. Les traductions néerlandaises des romans francophones camerounais

    African Journals Online (AJOL)

    28 mars 2016 ... deuxième s'intitule Der alte Mann und die Medaille. Le paratexte des textes publiés par la collection de Derde Spreker est avant tout didactique et en souligne la valeur documentaire: il importe que le lecteur place correctement le roman dans le contexte sociopolitique d'origine. Ainsi le titre original.

  3. Acoustics of ancient Greek and Roman theaters in use today

    DEFF Research Database (Denmark)

    Gade, Anders Christian; Angelakis, Konstantinos

    2006-01-01

    In the Mediteranan area a large number of open, ancient Greek and Roman theatres are still today facing a busy schedule of performances including both classical and contemporary works of dance, drama, concerts, and opera. During the EU funded ``Erato'' project and a subsequent master thesis project...

  4. The Roman Hannibal: Remembering the Enemy in Silius Italicus' Punica

    NARCIS (Netherlands)

    Stocks, C.A.

    2014-01-01

    This book offers a new reading of Hannibal in Silius Italicus' Punica and provides fresh insight into how the Romans remembered their past. Silius Italicus' Punica, the longest surviving epic in Latin literature, has seen a resurgence of interest among scholars in recent years. A celebration of

  5. Recycle Glass in Foam Glass Production

    DEFF Research Database (Denmark)

    Petersen, Rasmus Rosenlund; König, Jakob; Yue, Yuanzheng

    The foam glass industry turn recycle glass into heat insulating building materials. The foaming process is relative insensitive to impurities in the recycle glass. It is therefore considered to play an important role in future glass recycling. We show and discuss trends of use of recycled glasses...... in foam glass industry and the supply sources and capacity of recycle glass....

  6. Evaluation of Contact Friction in Fracture of Rotationally Bent Nitinol Endodontic Files

    Science.gov (United States)

    Haimed, Tariq Abu

    2011-12-01

    The high flexibility of rotary Nitinol (Ni-Ti) files has helped clinicians perform root canal treatments with fewer technical errors than seen with stainless steel files. However, intracanal file fracture can occur, compromising the outcome of the treatment. Ni-Ti file fracture incidence is roughly around 4% amongst specialists and higher amongst general practitioners. Therefore, eliminating or reducing this problem should improve patient care. The aim of this project was to isolate and examine the role of friction between files and the canal walls of the glass tube model, and bending-related maximum strain amplitudes, on Ni-Ti file lifetimes-tofracture in the presence of different irrigant solutions and file coatings. A specifically designed device was used to test over 300 electropolished EndoSequenceRTM Ni-Ti files for number of cycles to failure (NCF) in smooth, bent glass tube models at 45 and 60 degrees during dry, coated and liquid-lubricated rotation at 600rpm. Fractured files were examined under Scanning Electron Microscopy (SEM) afterwards. Four different file sizes 25.04, 25.06, 35.04, 35.06 (diameter in mm/taper %) and six surface modification conditions were used independently. These conditions included, three solutions; (1) a surfactant-based solution, Surface-Active-Displacement-Solution (SADS), (2) a mouth wash proven to remove biofilms, Delmopinol 1%(DEL), and (3) Bleach 6% (vol.%), the most common antibacterial endodontic irrigant solution. The conditions also included two low-friction silane-based coating groups, 3-Hepta-fluoroisopropyl-propoxymethyl-dichlorosilane (3-HEPT) and Octadecyltrichlorosilane (ODS), in addition to an as-received file control group (Dry). The coefficient of friction (CF) between the file and the canal walls for each condition was measured as well as the surface tension of the irrigant solutions and the critical surface tension of the coated and uncoated files by contact angle measurements. The radius of curvature and

  7. Designing biocompatible Ti-based metallic glasses for implant applications

    International Nuclear Information System (INIS)

    Calin, Mariana; Gebert, Annett; Ghinea, Andreea Cosmina; Gostin, Petre Flaviu; Abdi, Somayeh; Mickel, Christine; Eckert, Jürgen

    2013-01-01

    Ti-based metallic glasses show high potential for implant applications; they overcome in several crucial respects their well-established biocompatible crystalline counterparts, e.g. improved corrosion properties, higher fracture strength and wear resistance, increased elastic strain range and lower Young's modulus. However, some of the elements required for glass formation (e.g. Cu, Ni) are harmful for the human body. We critically reviewed the biological safety and glass forming tendency in Ti of 27 elements. This can be used as a basis for the future designing of novel amorphous Ti-based implant alloys entirely free of harmful additions. In this paper, two first alloys were developed: Ti 75 Zr 10 Si 15 and Ti 60 Nb 15 Zr 10 Si 15 . The overheating temperature of the melt before casting can be used as the controlling parameter to produce fully amorphous materials or bcc-Ti-phase reinforced metallic glass nano-composites. The beneficial effect of Nb addition on the glass-formation and amorphous phase stability was assessed by X-ray diffraction, transmission electron microscopy and differential scanning calorimetry. Crystallization and mechanical behavior of ribbons are influenced by the amount and distribution of the nano-scaled bcc phase existing in the as-cast state. Their electrochemical stability in Ringer's solution at 310 K was found to be significantly better than that of commercial Ti-based biomaterials; no indication for pitting corrosion was recorded. Highlights: ► Link between biocompatibility and glass-forming ability of alloying additions in Ti ► Selection of Ti–Zr–Si and Ti–Zr–Nb–Si glass-forming alloys ► Two novel glassy alloys were developed: Ti 75 Zr 10 Si 15 and Ti 60 Nb 15 Zr 10 Si 15. ► Glass-formation, thermal stability, corrosion and mechanical behavior were studied. ► Assessing the suitability for orthopedic applications.

  8. Tests of a Roman Pot Prototype for the TOTEM Experiment

    CERN Document Server

    Deile, M.; Anelli, G.M.; Antchev, G.A.; Ayache, M.; Caspers, F.; Dimovasili, E.; Dinapoli, R.; Drouhin, F.D.; Eggert, K.; Escourrou, L.; Fochler, O.; Gill, K.; Grabit, R.; Haug, F.; Jarron, P.; Kaplon, J.; Kroyer, T.; Luntama, T.; Macina, D.; Mattelon, E.; Mirabito, L.; Niewiadomski, H.; Noschis, E.P.; Oriunno, M.; Park, A.; Perrot, A.L.; Pirotte, O.; Quetsch, J.M.; Regnier, F.; Ruggiero, G.; Saramad, S.; Siegrist, P.; Snoeys, W.; Souissi, T.; Szczygiel, R.; Troska, J.; Vasey, F.; Verdier, A.; Avati, V.; Jarvinen, M.; Kalliokoski, M.; Kalliopuska, J.; Kurvinen, K.; Lauhakangas, R.; Oljemark, F.; Orava, R.; Palmieri, V.; Saarikko, H.; Soininen, A.; Osterberg, K.; Berardi, V.; Catanesi, M.G.; Radicioni, E.; Boccone, V.; Bozzo, M.; Buzzo, A.; Cuneo, S.; Ferro, F.; Macri, M.; Minutoli, S.; Morelli, A.; Musico, P.; Negri, M.; Santroni, A.; Sette, G.; Sobol, A.; Da Via, C.; Hasi, J.; Kok, A.; Watts, S.; Kasper, J.; Kundrat, V.; Lokajicek, M.; Smotlacha, J.

    2005-01-01

    The TOTEM collaboration has developed and tested the first prototype of its Roman Pots to be operated in the LHC. TOTEM Roman Pots contain stacks of 10 silicon detectors with strips oriented in two orthogonal directions. To measure proton scattering angles of a few microradians, the detectors will approach the beam centre to a distance of 10 sigma + 0.5 mm (= 1.3 mm). Dead space near the detector edge is minimised by using two novel "edgeless" detector technologies. The silicon detectors are used both for precise track reconstruction and for triggering. The first full-sized prototypes of both detector technologies as well as their read-out electronics have been developed, built and operated. The tests took place first in a fixed-target muon beam at CERN's SPS, and then in the proton beam-line of the SPS accelerator ring. We present the test beam results demonstrating the successful functionality of the system despite slight technical shortcomings to be improved in the near future.

  9. Tests of a Roman Pot prototype for the TOTEM experiment

    Science.gov (United States)

    Deile, M.; Alagoz, E.; Anelli, G.; Antchev, G.; Ayache, M.; Caspers, F.; Dimovasili, E.; Dinapoli, R.; Drouhin, F.; Eggert, K.; Escourrou, J.L; Fochler, O.; Gill, K.; Grabit, R.; Haung, F.; Jarron, P.; Kaplon, J.; Kroyer, T.; Luntama, T.; Macina, D.; Mattelon, E.; Niewiadomski, H.; Mirabito, L.; Noschis, E.P.; Oriunno, M.; Park, a.; Perrot, A.-L.; Pirotte, O.; Quetsch, J.M.; Regnier, F.; Ruggiero, G.; Saramad, S.; Siegrist, P.; Snoeys, W.; sSouissi, T.; Szczygiel, R.; Troska, J.; Vasey, F.; Verdier, A.; Da Vià, C.; Hasi, J.; Kok, A.; Watts, S.; Kašpar, J.; Kundrát, V.; Lokajíček, M.V.; Smotlacha, J.; Avati, V.; Järvinen, M.; Kalliokoski, M.; Kalliopuska, J.; Kurvinen, K.; Lauhakangas, R.; Oljemark, F.; Orava, R.; Österberg, K.; Palmieri, V.; Saarikko, H.; Soininen, A.; Boccone, V.; Bozzo, M.; Buzzo, A.; Cuneo, S.; Ferro, F.; Macrí, M.; Minutoli, S.; Morelli, A.; Musico, P.; Negri, M.; Santroni, A.; Sette, G.; Sobol, A.; sBerardi, V.; Catanesi, M.G.; Radicioni, E.

    The TOTEM collaboration has developed and tested the first prototype of its Roman Pots to be operated in the LHC. TOTEM Roman Pots contain stacks of 10 silicon detectors with strips oriented in two orthogonal directions. To measure proton scattering angles of a few microradians, the detectors will approach the beam centre to a distance of 10 sigma + 0.5 mm (= 1.3 mm). Dead space near the detector edge is minimised by using two novel "edgeless" detector technologies. The silicon detectors are used both for precise track reconstruction and for triggering. The first full-sized prototypes of both detector technologies as well as their read-out electronics have been developed, built and operated. The tests took place first in a fixed-target muon beam at CERN's SPS, and then in the proton beam-line of the SPS accelerator ring. We present the test beam results demonstrating the successful functionality of the system despite slight technical shortcomings to be improved in the near future.

  10. [Bonding of visible light cured composite resins to glass ionomer and Cermet cements].

    Science.gov (United States)

    Kakaboura, A; Vougiouklakis, G

    1990-04-01

    The "sandwich" technique involves combination of composite resins to etched glassionomer cements, is used today in restorative dentistry. The purpose of this study is to evaluate the bond strength between several composite resins and glass ionomer or cerment cements. Cylindrical specimens of the cements Ketac-Silver, Ionobond and GC-Lining Ce-ment were inserted in a mold and their flat free surfaces were etched for 30". Cylindrical plastic tubes were set upon each one of these surfaces and filled with the Composite resins Durafill, Brilliant Lux, Estilux posterior, Estilux posterior CVS and Herculite XR. Half of the specimens transferred in tap water for 24 hours and the others after thermocycling in the first month, kept for 4 months. Shear bond strengths were determined in Monsanto Testing Machine and some fractured surfaces were examined under SEM. The results of this investigation indicate that this technique produces bond strengths between composite resins and glassioners and the combination type of resin and type of cement, affects the values of the strength. Glass cermeet--small particle resin provides the most effective strength and glass ionomer--microfill resins the least. Storage time and thermocycling don't significantly effect the bond strength. SEM examination showed that all fracture failures were obtained in the cement while the opposite resin surfaces were covered with particles of the cements.

  11. Preparation of lead oxide nanoparticles from cathode-ray tube funnel glass by self-propagating method.

    Science.gov (United States)

    Wang, Yu; Zhu, Jianxin

    2012-05-15

    This paper presents a novel process of extracting lead oxide nanoparticles from cathode-ray tube (CRT) funnel glass using self-propagating high-temperature synthesis (SHS) method. The impacts of added amount of funnel glass on the extraction ratio of lead, the lead extraction velocity and the micromorphology, as well as particle size of extracted nanoparticles were investigated. We found that self-propagating reaction in the presence of Mg and Fe(2)O(3) could separate lead preferentially and superfine lead oxide nanoparticles were obtained from a collecting chamber. The separation ratio was related closely to the amount of funnel glass added in the original mixture. At funnel glass addition of no more than 40wt.%, over 90wt.% of lead was recovered from funnel glass. High extraction yield reveals that the network structure of funnel glass was fractured due to the dramatic energy generated during the SHS melting process. The PbO nanoparticles collected show good dispersion and morphology with a mean grain size of 40-50nm. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. RESEARCH REGARDING THE FREQUENCY AND TRANSMISSION OF AB0 BLOOD GROUPS IN A POPULATION OF PUPILS FROM ROMAN, NEAMŢ COUNTY

    OpenAIRE

    Ion Bara; Emiliana Randunica; Cristian Tudose; Iuliana Csilla Bara

    2007-01-01

    Part of a larger study regarding the genetic polymorphisms present in the human population of Romania, we have studied the frequency and transmission of AB0 blood groups in Roman, Neamţ County. We have investigated a population of school-boys from Roman town, Neamţ County. The blood groups frequency were: 0 = 30%; A = 42%; B = 19%; AB = 9%. These values are in accordance with the values registered for all Romanian population. In Roman town, between 2001-2004, the frequency of ...

  13. Fracture resistance of prepared premolars restored with bonded new lab composite and all-ceramic inlay/onlay restorations: Laboratory study.

    Science.gov (United States)

    Wafaie, Ramy Ahmed; Ibrahim Ali, Ashraf; Mahmoud, Salah Hasab

    2018-01-25

    To assess the influence of new light curing lab composite, lithium-disilicate glass-ceramic and yttrium-stabilized zirconia-based ceramic on the fracture resistance of maxillary premolars with class II inlay and onlay preparations. Seventy sound maxillary premolars were divided randomly into seven main groups. The first group was left intact (control group). The remaining six groups were prepared with inlay and onlay cavities and restored with lab composite (SR Nexco), lithium-disilicate glass-ceramic (IPS e.max Press) and yttrium-stabilized zirconia-based ceramic (ICE Zirkon). The restorations were cemented with luting resin composite (Variolink N). All specimens were thermocycled 5000 cycles between 5°C ± 2°C and 55°C ± 2°C and were then cyclic loaded for 500 000 cycles. The specimens were subjected to a compressive load in a universal testing machine using a metal sphere until fracture occurred. The results were analyzed by 2-way ANOVA and Tukey HSD post hoc tests. The level of significance was set at P  .05). However, statistically significant differences were found among the means of control group and the groups restored with lab composite inlays, lab composite onlays, pressable glass ceramic inlays and pressable glass ceramic onlays (P lab composite is used. Conversely, when a ceramic material being used, the prepared teeth for inlay and onlay restorations showed a comparable strength to the intact teeth especially zirconia ceramic. Premolar teeth restored with zirconia ceramic inlays and onlays exhibited fracture resistance comparable to intact teeth. © 2018 Wiley Periodicals, Inc.

  14. Reduced wear of enamel with novel fine and nano-scale leucite glass-ceramics.

    Science.gov (United States)

    Theocharopoulos, Antonios; Chen, Xiaohui; Hill, Robert; Cattell, Michael J

    2013-06-01

    Leucite glass-ceramics used to produce all-ceramic restorations can suffer from brittle fracture and wear the opposing teeth. High strength and fine crystal sized leucite glass-ceramics have recently been reported. The objective of this study is to investigate whether fine and nano-scale leucite glass-ceramics with minimal matrix microcracking are associated with a reduction in in vitro tooth wear. Human molar cusps (n=12) were wear tested using a Bionix-858 testing machine (300,000 simulated masticatory cycles) against experimental fine crystal sized (FS), nano-scale crystal sized (NS) leucite glass-ceramics and a commercial leucite glass-ceramic (Ceramco-3, Dentsply, USA). Wear was imaged using Secondary Electron Imaging (SEI) and quantified using white-light profilometry. Both experimental groups were found to produce significantly (pceramic) loss than the FS group. Increased waviness and damage was observed on the wear surfaces of the Ceramco-3 glass-ceramic disc/tooth group in comparison to the experimental groups. This was also indicated by higher surface roughness values for the Ceramco-3 glass-ceramic disc/tooth group. Fine and nano-sized leucite glass-ceramics produced a reduction in in vitro tooth wear. The high strength low wear materials of this study may help address the many problems associated with tooth enamel wear and restoration failure. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Development of Composite Materials Under Ecological Aspects as Recycling Concept For Borosilicate Glass Containing Iron Slags

    International Nuclear Information System (INIS)

    Khalil, T.K.; Bossert, J.; Aly, H.F.; Bossert, J.

    1999-01-01

    Composite concept in materials science can be conveniently applied in the waste treatment technology to construct specific t ailor made c omposite materials, in which at least one of the phases is built by the waste material. In this work the applicability of this concept for the fixation and recycling of slags wastes is done, whereby different mixtures of blast furnace slags are mixed with two different borosilicate glasses, which serve as matrix material. Thermal behaviour of the produced compacts were studied. Both melting and powder technology are applied for the fabrication of dense products. The microstructure of sintered samples is investigated by electron microscopy. The mechanical properties such as hardness and fracture toughness are determined by a Vickers technique. An improvement of the fracture toughness of more than 50% over the value for the original glass VG 98 is achieved by slag addition

  16. The crushing truth about glass ionomer restoratives: exposing the standard of the standard.

    LENUS (Irish Health Repository)

    Fleming, Garry J P

    2012-03-01

    The compressive fracture strength (CFS) test is the only strength test for glass ionomers (GIs) in ISO 9917-1: 2003. The CFS test was the subject of much controversy in 1990 and has been challenged over its appropriateness and reproducibility and the study aimed to revisit the suitability of the CFS test for GIs.

  17. Effects of superimposed hydrostatic pressure on flow and fracture of a Zr-Ti-Ni-Cu-Be bulk amorphous alloy

    International Nuclear Information System (INIS)

    Lowhaphandu, P.; Montgomery, S.L.; Lewandowski, J.J.

    1999-01-01

    Recent successes in producing bulk amorphous alloys have renewed interest in this class of materials. Although amorphous metallic alloys have been shown to exhibit strengths in excess of 2.0 GPa, most of the earlier studies on such materials were conducted on tape or ribbon specimens due to the high cooling rates required to achieve the amorphous structure. The primary purpose of this investigation was to determine the effects of superimposed hydrostatic pressure on the flow and fracture behavior of a Zr-Ti-Ni-Cu-Be bulk metallic glass utilizing procedures successfully utilized on a range of structural materials, as reviewed recently. In general, few studies of this type have been conducted on metallic glasses, although thin ribbons (i.e., 300 microm thick) of a Pd-Cu-Si amorphous material tested with superimposed pressure have been reported previously. In particular, the effects of superimposed hydrostatic pressure over levels ranging from 50 MPa to 575 MPa on the flow/fracture behavior of cylindrical tensile specimens were compared to the flow and fracture behavior of identical materials tested in uniaxial tension and compression. It is shown that changes in stress triaxiality, defined as σ m /bar σ, over the range of -0.33 to 0.33 produced a negligible effect on the fracture stress and fracture strain, while the orientation of the macroscopic fracture plane with respect to the loading axis was significantly affected by changes in σ m /bar σ

  18. Ancient Topometry, the Tracing of Towns in the Roman Epoch: Ulpia Traiana Dacica Sarmizegetusa - Romania. Second Part

    Science.gov (United States)

    Stanescu, Florin

    2015-05-01

    While following the rituals and the ancient topometrical methods used by the Romans in tracing cities according to the Etruscan tradition, this paper presents the historical, anthropological and archaeological aspects, analyzing techniques being used and aims at determining the day when there was inaugurated after the 2nd Dacian-Roman war, 105-106 AD, the new capital, Colonia Ulpia Traiana Augusta Dacica Sarmizegetusa, of the new province of Roman Empire, "Dacia Felix". The aspects of the problem which require a special archaeoastronomical and archaeometrical analysis are the physical horizon and the sun's movement. The provisional results obtained so far lead to the conclusion that the capital might have been traced in the 15-18 september period, that coincided with Emperor Trajan's birthday.

  19. Traditional and New Enhancing Human Cybernetic and Nanotechnological Body Modification Technologies: A Comparative Study of Roman Catholic and Transhumanist Ethical Approaches

    Science.gov (United States)

    Caligiuri, Michael J.

    Advances in cybernetic and nanotechnological body modifications currently allow for enhancements to human physical and mental function which exceed human species-based norms. This thesis examines body modification and human enhancement from two perspectives---Roman Catholicism and Transhumanism--- in order to contribute to bioethical deliberations regarding enhancement technologies. Roman Catholicism has a longstanding tradition of bioethical discourse, informing the healthcare directives of Roman Catholic institutions. Transhumanism is more recent movement that endorses body modifications and human enhancements as a means of individual betterment and social evolution. The thesis first considers definitions of human enhancement and levels of normalcy in connection to cybernetic and nanotechnological bionic implants, and outlines a series of criteria to assess a technology's potential bioethical acceptability: implantability, permanency, power, and public interaction. The thesis then describes Roman Catholicism's response to non-enhancing decorative body modifications (cosmetic surgeries, common decorative modifications such as tattoos and piercings, and uncommon modifications such as scarifications and brandings) in order to establish a basis for possible Roman Catholic responses to enhancing cybernetic and nanotechnological modifications. This is followed by an analysis from a Roman Catholic perspective of the major social issues brought forward by enhancement technologies: commodification, eugenics, vulnerability, and distributive justice. Turning to Transhumanism, the thesis describes the origins and philosophy of the movement, and then discusses the bioethical principles it advances with regard to human enhancement. The thesis concludes by locating points of convergence between Transhumanism and Roman Catholicism that could be the basis of more widely accepted ethical guidelines regarding modification technologies.

  20. Bone tuberculosis in Roman Period Pannonia (western Hungary

    Directory of Open Access Journals (Sweden)

    Tamás Hajdu

    2012-12-01

    Full Text Available The purpose of this study was to analyse a skeleton (adult female, 25-30 years that presented evidence of tuberculous spondylitis. The skeleton, dated from the Roman Period (III-VI centuries, was excavated near the town of Győr, in western Hungary. The skeleton was examined by gross observation supplemented with mycolic acid and proteomic analyses using MALDI-TOF/TOF tandem mass spectrometry. The biomolecular analyses supported the morphological diagnosis.

  1. Development and experimental evaluation of models for low capillary number two-phase flows in rough walled fractures relevant to natural gradient conditions

    International Nuclear Information System (INIS)

    Glass, R.J.; Yarrington, L.; Nicholl, M.J.

    1997-09-01

    The major results from SNL's Conceptual Model Development and Validation Task (WBS 1.2.5.4.6) as developed through exploration of small scale processes were synthesized in Glass et al. to give guidance to Performance Assessment on improving conceptual models for isothermal flow in unsaturated, fractured rock. There, pressure saturation and relative permeability curves for single fractures were proposed to be a function of both fracture orientation within the gravity field and initial conditions. We refer the reader to Glass et al. for a discussion of the implications of this behavior for Performance Assessment. The scientific research we report here substantiates this proposed behavior. We address the modeling of phase structure within fractures under natural gradient conditions relevant to unsaturated flow through fractures. This phase structure underlies the calculation of effective properties for individual fractures and hence fracture networks as required for Performance Assessment. Standard Percolation (SP) and Invasion Percolation (IP) approaches have been recently proposed to model the underlying phase saturation structures within the individual fractures during conditions of two-phase flow. Subsequent analysis of these structures yields effective two-phase pressure-saturation and relative permeability relations for the fracture. However, both of these approaches yield structures that are at odds with physical reality as we see in experiments and thus effective properties calculated from these structures are in error. Here we develop and evaluate a Modified Invasion Percolation (MIP) approach to better model quasi-static immiscible displacement in fractures. The effects of gravity, contact angle, local aperature field geometry, and local in-plane interfacial curvature between phases are included in the calculation of invasion pressure for individual sites in a discretized aperture field

  2. Diet, social differentiation and cultural change in Roman Britain

    DEFF Research Database (Denmark)

    Cheung, Christina; Schroeder, Hannes; Hedges, R. E. M.

    2012-01-01

    This study uses stable isotope analyses (d 13 C and d 15 N) of human bone collagen to reconstruct the diet of three Romano-British (first to early fifth century AD) populations from Gloucestershire in South West England. Gloucestershire was an important part of Roman Britain with two major admini...... sensitive, if settlement-specific, indicator of social differentiation and culture change....

  3. Fracture load of different crown systems on zirconia implant abutments.

    Science.gov (United States)

    Albrecht, T; Kirsten, A; Kappert, H F; Fischer, H

    2011-03-01

    The purpose of this study was to evaluate the fracture load of single zirconia abutment restorations using different veneering techniques and materials. The abutment restorations were divided into 6 groups with 20 samples each: test abutments (control group A), lithium disilicate ceramic crowns bonded on incisor abutments (group B), leucite ceramic crowns bonded on incisor abutments (group C), premolar abutments directly veneered with a fluor apatite ceramic (group D (layered) and group E (pressed)) and premolar abutments bonded with lithium disilicate ceramic crowns (group F). The fracture load of the restorations was evaluated using a universal testing machine. Half of each group was artificially aged (chewing simulation and thermocycling) before evaluating the fracture load with the exception of the test abutments. The fracture load of the test abutments was 705 ± 43N. Incisor abutments bonded with lithium disilicate or leucite ceramic crowns (groups B and C) showed fracture loads of about 580N. Premolar restorations directly veneered with fluor apatite ceramic (groups D and E) showed fracture loads of about 850N. Premolar restorations bonded with lithium disilicate ceramic crowns (group F) showed fracture loads of about 1850N. The artificial ageing showed no significant influence on the strength of the examined restorations. All ceramic crowns made of lithium disilicate glass-ceramic, adhesively bonded to premolar abutments showed the highest fracture loads in this study. However, all tested groups can withstand physiological bite forces. Copyright © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  4. Querns and mills during Roman times at the northern frontier of the Roman Empire (Belgium, Northern France, Southern Netherlands, Western Germany: Unraveling geological and geographical provenances, a multidisciplinary research project

    Directory of Open Access Journals (Sweden)

    Sibrecht Reniere

    2016-10-01

    Full Text Available This paper presents the results of a multi-disciplinary provenance study of querns and millstones during the Roman period (1st-4th century CE in the northern part of the Roman Empire (provinces of Gallia Belgica and Germania Inferior. Comparative petrographical, mineralogical and geochemical analysis allowed an international team of archaeologists and geologists to identify the different raw materials used for the manufacturing of querns and millstones. As a result, (litho- stratigraphic assignments as well as geological-geographical provenances are suggested or corroborated for the broad spectrum of these natural geo-materials. We give evidence for the exploitation of at least seven different rock types. They include sedimentary rocks (fine- to coarse-grained quartzitic and arkosic sandstones, conglomerates, limestones and volcanic rocks (vesicular lavas derived from different geological strata in the following geological-geographical settings: the volcanic Eifel area (Pleistocene lava, the Ardennes Massif (Palaeozoic sedimentary rocks and the Paris and Northern Sea Basin (Cenozoic sedimentary rocks. Furthermore we show that a large diversity existed within different productions (different types of hand-mills and mechanical powered mills and distribution patterns. This paper provides new data which will lead to new insights into the socio-economics of the local “Gallo-Roman” communities and into their networks within the northern Roman Empire.

  5. Roman Lyariev, How to Skin Your Kill

    OpenAIRE

    Gedeeva, Darina; Ubushieva, Bamba; Babaev, Andrei

    2016-01-01

    Roman explains how to skin a fox. First, one needs to prepare the ground by trampling it. Skinning should be done with a small sharp knife. A freshly killed fox skins easily. Then one needs to treat the skin with an anti-flea spray. At home the skin should be stretched on a triangular wooden panel called in Russian pravilka and left in a dry room for up to five days. People usually go hunting when foxes are on heat and are busy fighting with each other for females. When the wind is strong, fo...

  6. THE ROMAN-CATHOLIC DEFINITIONS TO COMMEMORATIVE PARTICLES

    Directory of Open Access Journals (Sweden)

    MICHAIL ASMUS

    2008-11-01

    Full Text Available The author overviews and analyses selected Roman-Catholic theological texts deal-ing with the meaning of commemorative particles in the Protesis of the Byzantine rite dating back to the XV–XVIII centuries. Peter Arcudius is the key person because it was his theological doctrine that in 1720 brought on the Counsil decision about the trans-substantiation of particles. This work gives further development to the previous study of the particles’ conception in the Orthodox East carried out by the author in 2005 and published in this review (issue 14, 2005.

  7. An ovarian teratoma of late Roman age.

    Science.gov (United States)

    Armentano, Núria; Subirana, Mercè; Isidro, Albert; Escala, Oscar; Malgosa, Assumpció

    2012-12-01

    We report here a very unusual pelvic calcification recovered from the remains of a 30-40-year-old woman found at the late Roman period archeological site of La Fogonussa (Lleida, Catalonia). Although differential diagnoses for calcifications of the pelvis are complicated in archeological contexts, the precise localization, macroscopic features, and the presence of teeth along with part of a small bone led us to identify this case as an ovarian teratoma, based upon gross observations and computerized tomography (CT). Copyright © 2012 Elsevier Inc. All rights reserved.

  8. Some remarks on the transitional phase between Early Roman and Late Roman Periods in the region north of the Middle Danube

    Czech Academy of Sciences Publication Activity Database

    Tejral, Jaroslav

    2015-01-01

    Roč. 56, č. 2 (2015), s. 43-101 ISSN 1211-7250 Institutional support: RVO:68081758 Keywords : Early and Late Roman Period * transitional phase * Marcomanic Wars and their aftermath * ethnical and social backround of the B2/C1 phase Subject RIV: AC - Archeology, Anthropology, Ethnology http://prehled-vyzkumu.arub.avcr.cz/miranda2/export/sitesavcr/arub-prehled-vyzkumu/prehled-cisel-a-clanku/prehled-vydanych-cisel/files/PV56_2_Studie2_Tejral.pdf

  9. Preliminary remarks on the Roman military equipment from the war booty sacrifice of Viemose, Denmark

    DEFF Research Database (Denmark)

    Pauli Jensen, Xenia

    2007-01-01

    The article deals with the war booty sacrifice of Vimose, Denmark, where a vast amount of Roman military equipment was found. The Ring Pommel swords are discussed, especially the possible (or not so possible) link with the Marcomannic Wars 166-180 AD.......The article deals with the war booty sacrifice of Vimose, Denmark, where a vast amount of Roman military equipment was found. The Ring Pommel swords are discussed, especially the possible (or not so possible) link with the Marcomannic Wars 166-180 AD....

  10. Energy deposition in the window of the TOTEM Roman pot for the nominal TOTEM run

    CERN Document Server

    Dimovasili, E

    2005-01-01

    The TOTEM Roman Pot needs to be protected from possible accidents. One of the most serious accident scenarios is the beam loss during an asynchronous abort dump. In this case of dump failure it is possible that a deflected bunch hits the Roman Pot, causing severe damage to its thin window. This technical note discusses the results of FLUKA Monte Carlo studies that have been performed in order to calculate the energy deposition and the temperature increase in the thin window due to the nominal LHC bunch.

  11. Elemental analysis of forensic glasses by inductively coupled plasma mass spectrometry

    Science.gov (United States)

    Almirall, Jose R.; Duckworth, Douglas C.; Bayne, Charles K.; Morton, Sherman A.; Smith, David H.; Koons, Robert D.; Furton, Kenneth G.

    1999-02-01

    Flat glass is a common type of evidence collected from the scenes of crimes such as burglaries, vandalism, and hit-and- run accidents. The usefulness of such evidence lies in the ability to associate the glass from the scene (or a suspect) to the original source. Physical and chemical analysis of the glass can be used for discrimination between the possible sources of glass. If the sample is large enough, physical attributes such as fracture matches, density, color, and thickness can be employed for comparison between a recovered fragment(s) to the suspect source. More commonly, refractive index (RI) comparisons are employed. Due to the improved control over glass manufacturing processes, RI values often cannot differentiate glasses where approximately 6 - 9% of casework samples are not expected to be distinguished by RI alone even if they originated from different sources. Employing methods such as NAA, XRF, ICP-AES, and ICP-MS for the comparison of trace elemental compositions has been shown to be more discriminating than RI comparisons. The multielement capability and the sensitivity of ICP-AES and ICP-MS provide for excellent discrimination power. In this work, the sources of variability in ICP-MS of glass analysis are investigated to determine possible sources of variation. The sources of variation examined include errors due to sample preparation, instrument accuracy and precision, and interlaboratory reproducibility. Other sources of variation include inhomogeneity across a sheet of glass from the same source. Analysis of variance has been applied to our ICP-MS analysis of NIST standards and to the interlaboratory comparisons of float glass samples collected across a sheet in a production facility. The results of these experiments allows for a more accurate interpretation of forensic glass data and a better understanding of the discriminating power (absolute and practical) of ICP-MS.

  12. Compressive fatigue tests on a unidirectional glass/polyester composite at cryogenic temperatures

    International Nuclear Information System (INIS)

    Stone, E.L.; El-Marazki, L.O.; Young, W.C.

    1979-01-01

    The fatigue testing of a unidirectional glass-reinforced polyester composite at cryogenic temperatures to simulate the cyclic compressive loads of the magnet support struts in a superconductive magnetic energy storage unit is reported. Right circular cylindrical specimens were tested at 77, 4.2 K and room temperature at different stress levels using a 1-Hz haversine waveform imposed upon a constant baseload in a load-controlled closed-loop electrohydraulic test machine. Two failure modes, uniform mushrooming near one end and a 45 deg fracture line through the middle of the specimen, are observed, with no systematic difference in fatigue life between the modes. Fatigue lives obtained at 77 and 4.2 K are found to be similar, with fatigue failure at 100,000 cycles occurring at stress levels of 70 and 75% of the ultimate compressive strengths of specimens at room temperature and 77 K, respectively. The room temperature fatigue lives of the glass/polyester specimens are found to be intermediate between those reported for glass/epoxy composites with different glass contents costing over twice as much

  13. On the origin of patterning in movable Latin type : Renaissance standardisation, systematisation, and unitisation of textura and roman type

    NARCIS (Netherlands)

    Blokland, F.E.

    2016-01-01

    This PhD-research is conducted to test the hypothesis that Gutenberg and consorts developed a standardised and even unitised system for the production of textura type, and that this system was extrapolated for the production of roman type in Renaissance Italy. For roman type, Humanistic handwriting

  14. Deformation Mechanisms and Fracture of Ni-Based Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Lesz S.

    2016-06-01

    Full Text Available The cracking of materials and fracture surface is of great practical and academic importance. Over the last few years the development of the fractography of crystalline alloys resulted in a useful tool for the prediction or failure analysis. Many attempts have been made to observe cracks using optical microscopy, X-ray topography and transmission electron microscopy (TEM. Of these techniques, the resolution of optical microscopy and X-ray topography is too poor. By contrast, the resolution of TEM is high enough for detailed information to be obtained. However, in order to apply TEM observations, a thin foil specimen must be prepared, and it is usually extremely difficult to prepare such a specimen from a pre-selected region containing a crack.

  15. Effect of ZrO(2) additions on the crystallization, mechanical and biological properties of MgO-CaO-SiO(2)-P(2)O(5)-CaF(2) bioactive glass-ceramics.

    Science.gov (United States)

    Li, H C; Wang, D G; Meng, X G; Chen, C Z

    2014-06-01

    A series of ZrO(2) doped MgO-CaO-SiO(2)-P(2)O(5)-CaF(2) bioactive glass-ceramics were obtained by sintering method. The crystallization behavior, phase composition, morphology and structure of glass-ceramics were characterized. The bending strength, elastic modulus, fracture toughness, micro-hardness and thermal expansion coefficient (TEC) of glass-ceramics were investigated. The in vitro bioactivity and cytotoxicity tests were used to evaluate the bioactivity and biocompatibility of glass-ceramics. The sedimentation mechanism and growth process of apatites on sample surface were discussed. The results showed that the mainly crystalline phases of glass-ceramics were Ca(5)(PO4)3F (fluorapatite) and β-CaSiO(3). (β-wollastonite). m-ZrO(2) (monoclinic zirconia) declined the crystallization temperatures of glasses. t-ZrO(2) (tetragonal zirconia) increased the crystallization temperature of Ca(5)(PO4)(3)F and declined the crystallization temperature of β-CaSiO(3). t-ZrO(2) greatly increased the fracture toughness, bending strength and micro-hardness of glass-ceramics. The nanometer apatites were induced on the surface of glass-ceramic after soaking 28 days in SBF (simulated body fluid), indicating the glass-ceramic has good bioactivity. The in vitro cytotoxicity test demonstrated the glass-ceramic has no toxicity to cell. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Characterisation of glass matrix composites reinforced with lead zirconate titanate particles

    International Nuclear Information System (INIS)

    Cannillo, Valeria; Manfredini, Tiziano; Montorsi, Monia; Tavoni, Francesca; Minay, Emma J.; Boccaccini, Aldo R.

    2005-01-01

    A new type of glass matrix composite reinforced with ferroelectric particulate secondary phase was investigated. Samples containing lead zirconate titanate (PZT) particles in a silicate lead glass were fabricated. Various sintering strategies were tested in order to optimise the processing route. The densest samples were obtained by hot-pressing. The composites were characterized by means of SEM observations, X-ray diffraction, differential thermal analysis and Vickers indentations. In order to get a deeper insight into the thermo-mechanical behaviour of the material, a FEM based numerical model was prepared and applied. In particular, the crack-particle interaction was assessed and thus possible toughening mechanisms were investigated. By means of the numerical modelling supported by SEM observations, traditional toughening mechanisms (e.g. crack deflection, particle debonding) were ruled out. Since the experimentally measured indentation fracture toughness of the composite is significantly higher than that of the unreinforced glass, the findings suggest that a new toughening mechanism may be active, based on the piezoelectric effect

  17. Glass ceramics for sealing to high-thermal-expansion metals

    International Nuclear Information System (INIS)

    Wilder, J.A. Jr.

    1980-10-01

    Glass ceramics were studied, formulated in the Na 2 O CaO.P 2 O 5 , Na 2 O.BaOP 2 O 5 , Na 2 O.Al 2 O 3 .P 2 O 5 , and Li 2 O.BaO.P 2 O 5 systems to establish their suitability for sealing to high thermal expansion metals, e.g. aluminum, copper, and 300 series stainless steels. Glass ceramics in Na 2 O.CaO.P 2 O 5 and Na 2 O.BaO.P 2 O 5 systems have coefficients of thermal expansion in the range 140 x 10 -1 per 0 C less than or equal to α less than or equal to 225 x 10 -7 per 0 C and fracture toughness values generally greater than those of phosphate glasses; they are suitable for fabricating seals to high thermal expansion metals. Crystal phases include NaPo 3 , (NaPO 3 ) 3 , NaBa(PO 3 ) 3 , and NaCa(PO 3 ) 3 . Glass ceramics formed in the Na 2 O.Al 2 O 3 .P 2 O 5 systems have coefficients of thermal expansion greater than 240 x 10 -7 per 0 C, but they have extensive microcracking. Due to their low thermal expansion values (α less than or equal to 120 x 10 -7 per 0 C), glass ceramics in the Li 2 O.BaO.P 2 O 5 system are unsuitable for sealing to high thermal expansion metals

  18. Friction and wear behavior of glasses and ceramics

    Science.gov (United States)

    Buckley, D. H.

    1973-01-01

    Adhesion, friction, and wear behavior of glasses and ionic solids are reviewed. These materials are shown to behave in a manner similar to other solids with respect to adhesion. Their friction characteristics are shown to be sensitive to environmental constituents and surface films. This sensitivity can be related to a reduction in adhesive bonding and the changes in surficial mechanical behavior associated with Rehbinder and Joffe effects. Both friction and wear properties of ionic crystalline solids are highly anisotropic. With metals in contact with ionic solids the fracture strength of the ionic solid and the shear strength in the metal and those properties that determine these will dictate which of the materials undergoes adhesive wear. The chemical activity of the metal plays an important role in the nature and strength of the adhesive interfacial bond that develops between the metal and a glass or ionic solid.

  19. Roman Sikora: Smetení Antigony - Pokus o tragédii (1998)

    Czech Academy of Sciences Publication Activity Database

    Vodička, Libor

    2005-01-01

    Roč. 53, č. 3 (2005), s. 413-422 ISSN 0009-0468 R&D Projects: GA ČR(CZ) GA405/03/1136 Institutional research plan: CEZ:AV0Z9056905 Keywords : theatre * Roman Sikora Subject RIV: AJ - Letters, Mass-media, Audiovision

  20. Cavitation instability in bulk metallic glasses

    Directory of Open Access Journals (Sweden)

    Dai L.H.

    2015-01-01

    Full Text Available Recent experiments have shown that fracture surfaces of bulk metallic glasses (BMGs usually exhibit an intriguing nanoscale corrugation like fractographic feature mediated by nanoscale void formation. We attribute the onset of this nanoscale corrugation to TTZs (tension transformation zones mediated cavitation. In our recent study, the spall experiments of Zr-based BMG using a single-stage light gas gun were performed. To uncover the mechanisms of the spallation damage nucleation and evolution, the samples were designed to be subjected to dynamic tensile loadings of identical amplitude but with different durations by making use of the multi-stress pulse and the double-flyer techniques. It is clearly revealed that the macroscopic spall fracture in BMGs originates from the nucleation, growth and coalescence of micro-voids. Then, a microvoid nucleation model of BMGs based on free volume theory is proposed, which indicates that the nucleation of microvoids at the early stage of spallation in BMGs is resulted from diffusion and coalescence of free volume. Furthermore, a theoretical model of void growth in BMGs undergoing remote dynamic hydrostatic tension is developed. The critical condition of cavitation instability is obtained. It is found that dynamic void growth in BMGs can be well controlled by a dimensionless inertial number characterizing the competition between intrinsic and extrinsic time scales. To unveil the atomic-level mechanism of cavitation, a systematic molecular dynamics (MD simulation of spallation behaviour of a binary metallic glass with different impact velocities was performed. It is found that micro-void nucleation is determined TTZs while the growth is controlled by shear transformation zones (STZs at atomic scale.

  1. L’identità narrativa ricœuriana alla prova del «nouveau roman» di Robbe-Grillet

    Directory of Open Access Journals (Sweden)

    Alberto Romele

    2013-12-01

    Full Text Available The present essay aims to connect Ricœur’s notion of narrative identity – developed between the 1980s and 1990s – with the nouveau roman theorized by Alain Robbe-Grillet in writings published between 1956 and 1963 and then collected in Pour un noveau roman. In the first part, the essay will summarize Ricœur’s  Aristotelian –apocalyptic narratology model in the light of a comparison with the work of Frank Kermode. In the second part, noveau roman’s ontic realism will be presented. Finally, in the third part, starting with a comparison with the world of computer games, the essay will trace the effect of the overlapping of noveau roman with narrative identity both on the level of description and prescription.

  2. A comparison of the microstructure and properties of the IPS Empress 2 and the IPS Empress glass-ceramics.

    Science.gov (United States)

    Höland, W; Schweiger, M; Frank, M; Rheinberger, V

    2000-01-01

    The aim of this report is to analyze the microstructures of glass-ceramics of the IPS Empress 2 and IPS Empress systems by scanning electron microscopy. The main properties of the glass-ceramics were determined and compared to each other. The flexural strength of the pressed glass-ceramic (core material) was improved by a factor of more than three for IPS Empress 2 (lithium disilicate glass-ceramic) in comparison with IPS Empress (leucite glass-ceramic). For the fracture toughness, the K(IC) value was measured as 3.3 +/- 0.3 MPa. m(0.5) for IPS Empress 2 and 1.3 +/- 0.1 MPa. m(0.5) for IPS Empress. Abrasion behavior, chemical durability, and optical properties such as translucency of all glass-ceramics fulfill the dental standards. The authors concluded that IPS Empress 2 can be used to fabricate 3-unit bridges up to the second premolar. Copyright 2000 John Wiley & Sons, Inc.

  3. Glass consistency and glass performance

    International Nuclear Information System (INIS)

    Plodinec, M.J.; Ramsey, W.G.

    1994-01-01

    Glass produced by the Defense Waste Processing Facility (DWPF) will have to consistently be more durable than a benchmark glass (evaluated using a short-term leach test), with high confidence. The DWPF has developed a Glass Product Control Program to comply with this specification. However, it is not clear what relevance product consistency has on long-term glass performance. In this report, the authors show that DWPF glass, produced in compliance with this specification, can be expected to effectively limit the release of soluble radionuclides to natural environments. However, the release of insoluble radionuclides to the environment will be limited by their solubility, and not glass durability

  4. Dynamic fatigue of a lithia-alumina-silica glass-ceramic

    Science.gov (United States)

    Tucker, Dennis S.

    1990-01-01

    A dynamic fatigue study was performed on a Li2O-Al2O3-SiO2 glass-ceramic in order to assess its susceptibility to delayed failure. Fracture mechanics techniques were used to analyze the results for the purpose of making lifetime predictions for optical elements made from this material. The material has reasonably good resistance (N = 20) to stress corrosion in ambient conditions. Analysis also indicated the elements should survive applied stresses incurred during grinding and polishing operations.

  5. Management of Horizontal Root Fracture in the Middle Third via Intraradicular Splinting Using a Fiber Post

    Directory of Open Access Journals (Sweden)

    Ishani Karhade

    2016-01-01

    Full Text Available Radicular fractures in permanent teeth are uncommon injuries and account for only 0.5–7% of dental traumas. These fractures commonly result from a horizontal impact and are transverse to oblique in direction. Their incidence is more in the middle third of the root than at the apical and cervical thirds. This paper describes a case of complicated crown fracture of maxillary incisors along with horizontal root fracture at the middle third of maxillary right central and lateral incisor. The fractured root fragments of the upper right central and lateral incisor were united with the help of a glass fiber post after receiving an endodontic treatment. The other two incisors were treated endodontically followed by post endodontic restorations. Eventually the four incisors were restored with porcelain fused to metal crowns. A one-year follow-up revealed a well stabilized assembly of the root fragments and the post.

  6. Mixture for producing fracture-resistant, fiber-reinforced ceramic material by microwave heating

    Science.gov (United States)

    Meek, T.T.; Blake, R.D.

    1985-04-03

    A fracture-resistant, fiber-reinforced ceramic substrate is produced by a method which involves preparing a ceramic precursor mixture comprising glass material, a coupling agent, and resilient fibers, and then exposing the mixture to microwave energy. The microwave field orients the fibers in the resulting ceramic material in a desired pattern wherein heat later generated in or on the substrate can be dissipated in a desired geometric pattern parallel to the fiber pattern. Additionally, the shunt capacitance of the fracture-resistant, fiber-reinforced ceramic substrate is lower which provides for a quicker transit time for electronic pulses in any conducting pathway etched into the ceramic substrate.

  7. Framing Egypt : Roman literary perceptions of Egypt from Cicero to Juvenal

    NARCIS (Netherlands)

    Leemreize, M.E.C.

    2016-01-01

    This is a comprehensive study of Roman literary references to Egypt without preference for one particular period, author or subject, in contrast to most previous scholarship. In doing so, it shows that these references vary greatly, are context-dependent, and cannot be rightly understood when

  8. Effect of reinforcement with resin composite on fracture strength of structurally compromised roots.

    Science.gov (United States)

    Fukui, Yuji; Komada, Wataru; Yoshida, Keiichi; Otake, Shiho; Okada, Daizo; Miura, Hiroyuki

    2009-09-01

    This study was aimed at evaluating the fracture resistance of structurally compromised roots restored with four different post and core systems. Thirty-two bovine roots were uniformly shaped to simulate human mandibular premolar roots. The roots were divided into four groups based on the type of restoration: cemented cast post and core (Group MC), resin composite build-up (Group CR), resin composite and prefabricated glass fiber post build-up (Group FRC), and thick-layer dual-cured resin composite-reinforced small-diameter tapered cast post and core (Group CRM). After a static loading test, the failure mode and fracture resistance were recorded. Group CRM (719.38+/-196.73 N) exhibited a significantly high fracture resistance compared with the other groups (Group MC: 429.56+/-82.43 N; Group CR: 349.56+/-66.21 N; Group FRC: 398.94+/-112.71 N; pCRM exhibited better mechanical properties for structurally compromised roots with no ferrules, although all types of restorations showed non-restorable fracture modes.

  9. Roman impact on the landscape near castellum Fectio, The Netherlands

    NARCIS (Netherlands)

    van den Bos, Valerie; Brinkkemper, Otto; Bull, Ian; Engels, Stefan; Hakbijl, Tom; Schepers, Mans; van Dinter, Marieke; van Reenen, Guido; van Geel, Bas

    2014-01-01

    Castellum Fectio was one of the largest fortifications along the Limes, the northern border of the Roman Empire. The castellum, situated 5 km southeast of Utrecht, the Netherlands, was occupied from around the start of our Era to ca. A.D. 260. It was situated along a river bend of the Rhine that was

  10. Suid-Afrikaanse romans in Afrikaans sowel as Engels; soms bloot ...

    African Journals Online (AJOL)

    8 Apr 2016 ... word in sommige van die collages wat elke hoofstuk voorafgaan. Benewens die gesprek met ouer, meer literêre werke, kan Botha se roman ook andersyds beskou word as deel van 'n bepaalde kontemporêre literêre beweging, waar- êre literêre beweging, waar- re literêre beweging, waar- êre beweging ...

  11. Roman impact on the landscape near castellum Fectio, The Netherlands

    NARCIS (Netherlands)

    van den Bos, V.; Brinkkemper, O.; Bull, I.D.; Engels, S.; Hakbijl, T.; Schepers, M.; Dinter, M.; van Reenen, G.; van Geel, B.

    2014-01-01

    Castellum Fectio was one of the largest fortifications along the Limes, the northern border of the Roman Empire. The castellum, situated 5 km southeast of Utrecht, the Netherlands, was occupied from around the start of our Era to ca. a.d. 260. It was situated along a river bend of the Rhine that was

  12. Transparent 3D Visualization of Archaeological Remains in Roman Site in Ankara-Turkey with Ground Penetrating Radar Method

    Science.gov (United States)

    Kadioglu, S.

    2009-04-01

    Transparent 3D Visualization of Archaeological Remains in Roman Site in Ankara-Turkey with Ground Penetrating Radar Method Selma KADIOGLU Ankara University, Faculty of Engineering, Department of Geophysical Engineering, 06100 Tandogan/ANKARA-TURKEY kadioglu@eng.ankara.edu.tr Anatolia has always been more the point of transit, a bridge between West and East. Anatolia has been a home for ideas moving from all directions. So it is that in the Roman and post-Roman periods the role of Anatolia in general and of Ancyra (the Roman name of Ankara) in particular was of the greatest importance. Now, the visible archaeological remains of Roman period in Ankara are Roman Bath, Gymnasium, the Temple of Augustus of Rome, Street, Theatre, City Defence-Wall. The Caesar Augustus, the first Roman Emperor, conquered Asia Minor in 25 BC. Then a marble temple was built in Ancyra, the administrative capital of province, today the capital of Turkish Republic, Ankara. This monument was consecrated to the Empreror and to the Goddess Rome. This temple is supposed to have built over an earlier temple dedicated to Kybele and Men between 25 -20 BC. After the death of the Augustus in 14AD, a copy of the text of "Res Gestae Divi Augusti" was inscribed on the interior of the pronaos in Latin, whereas a Greek translation is also present on an exterior wall of the cella. In the 5th century, it was converted in to a church by the Byzantines. The aim of this study is to determine old buried archaeological remains in the Augustus temple, Roman Bath and in the governorship agora in Ulus district. These remains were imaged with transparent three dimensional (3D) visualization of the ground penetrating radar (GPR) data. Parallel two dimensional (2D) GPR profile data were acquired in the study areas, and then a 3D data volume were built using parallel 2D GPR data. A simplified amplitude-colour range and appropriate opacity function were constructed and transparent 3D image were obtained to activate buried

  13. Vroue, nasie en verwoording in Sharai Mukonoweshuro se Shona-romans

    Directory of Open Access Journals (Sweden)

    Maurice T. Vambe

    2013-10-01

    Full Text Available Die doel van hierdie artikel is om die fiktiewe voorstelling van vroue in twee van Sharai Mukonoweshuro se romans, naamlik Ndakagara Ndazviona en Akafuratidzwa Moyo, te verken. Tradisionele Shona verwagtinge van hoe ’n vrou moet optree, skryf die rolle voor wat van vroue verwag word om in die samelewing te speel. In ’n koloniale konteks soos die voormalige Rhodesië het kolonialisme wette in die gewoontereg bedink wat vroue verder gedegradeer het tot sosiale posisies soortgelyk aan dié van minderjariges. Hoewel die nasionalistiese stryd in wese bedoel was om vryheid te waarborg vir alle Swart mense, ongeag van geslag, het die manlike elites Swart vroue as hul minderwaardige ‘ander‘ gekonstrueer. In hierdie artikel word geargumenteer dat Sharai Mukonoweshuro se romans worstel met hierdie manlik-goedgekeurde stereotipes. Maar, soos getoon word, Mukonoweshuro se wyse van weerstand teen vroulike stereotipes is ambivalent; die skrywer skep jong vroue wat die patriargie aan die een kant uitdaag, en aan die ander kant, ou vroue wat die ondenkbare doen om hulle eie seuns te vergiftig.

  14. Dynamic fatigue of a machinable glass-ceramic

    Science.gov (United States)

    Smyth, K. K.; Magida, M. B.

    1983-01-01

    To assess the stress-corrosion susceptibility of a machinable glass-ceramic, its dynamic fatigue behavior was investigated by measuring its strength as a function of stress rate. Fracture mechanics techniques were used to analyze the results for the purpose of making lifetime predictions for components of this material. This material was concluded to have only moderate resistance (N = 30) to stress corrosion in ambient conditions. The effects of specimen size on strength were assessed for the material used in this study; it was concluded that the Weibull edge-flaw scaling law adequately describes the observed strength-size relation.

  15. The contribution of intellectuals to the history of traumatology during the Renaissance: treatment of femoral fracture through François Rabelais' glossocomion.

    Science.gov (United States)

    Manzini, Francesco; Manzini, Claudio; Cesana, Giancarlo; Riva, Michele Augusto

    2017-02-01

    During the Middle Ages and the Renaissance, intellectuals often included clinical cases and medical descriptions in their literary works. These authors appeared to be more interested in internal and infectious diseases rather than in musculoskeletal disorders and orthopaedics. François Rabelais (1490-1553) was one of the most renowned humanists and philologists of the sixteenth century. He was also a physician with an interest in translating ancient texts of medical authors. Rabelais rediscovered a device for treating femoral fracture originally described by the Roman physician Galen and named as glossocomion. Since the original apparatus had some imperfections, Rabelais redesigned and modified it. This new, improved version became a model for new devices for treating femoral fracture, as also reported by the great French surgeon Ambroise Paré. For this contribution, Rabelais deserves major consideration in the history of orthopaedics and traumatology.

  16. Influence of microporosity on fracture stress of pyrocarbon coatings

    International Nuclear Information System (INIS)

    Krautwasser, P.; Nickel, H.; Taueber, K.

    1975-01-01

    In this paper recent investigations on fracture behaviour of integral PyC-coatings are presented. The fracture stresses of propene, acetylene, and methane-derived pyrocarbons are measured as a function of deposition temperature and deposition rate. The measured fracture stresses are interpreted in terms of microporosity values determined by X-ray small angle scattering (SAXS). It can be shown that the fracture stress is correlated unambigously with the concentration of micropores in the range of about 50 to 500A diameter. TEM inspection of the investigated materials revealed a component of disordered, tangled fibres with a high microporosity in agreement with SAXS results. This component increases with temperature in the range of 1250 to 1400 at the expense of of a high-density component. As a result, the coatings deposited in this temperature range show decreasing fracture stress with increasing amount of the porous glass wool like component. PyC coatings with a good irradiation behaviour had an initial pore size distribution typical for a relatively high content of tangled material. The assumption, that a relatively high amount of the disordered material is fafourable for a good behaviour i.e. integrity of coating up to high neutron doses, was confirmed besides other investigations by the relative low preirradiation fracture stresses of the well behaving coatings. This means, the integrity of pyrocarbon coatings after irradiation is favoured not so much by a high preirradiation fracture stress, but by the enhanced dimensional stability of the disordered porous material. In addition to this, the increase of the relatively low fractures stress due to the measured irradiation induced reduction of pores in the size range of 200 to 1000A diameter is in favour of coating integrity

  17. Structural relaxation and embrittlement of Cu/sub 59/Zr/sub 41/ and Fe/sub 80/B/sub 20/ glasses

    International Nuclear Information System (INIS)

    Deng, D.; Argon, A.S.

    1986-01-01

    The effect of physical aging at 0.92 T/sub c/, on phase separation, crystallization, distributed shear relaxations, hardness, and strain to fracture was investigated in Cu/sub 59/Zr/sub 41/ and Fe/sub 80/B/sub 20/ glasses. In Cu/sub 59/Zr/sub 41/ glass, aging resulted in phase separation prior to crystallization, rather than the expected polymorphous crystallization. In Fe/sub 80/B/sub 20/ in the as-quenched alloys a prominent second-order Curie transition was found at 613K, which was recovered by aging. Apart from a nearly four-fold acceleration of the aging process in Fe/sub 80/B/sub 20/ over the Cu/sub 59/Zr/sub 41/ alloy, their mechanical responses to the aging were very similar in alterations of the internal friction spectrum, evolution of hardness, and strain to fracture

  18. Bifurcating Particle Swarms in Smooth-Walled Fractures

    Science.gov (United States)

    Pyrak-Nolte, L. J.; Sun, H.

    2010-12-01

    Particle swarms can occur naturally or from industrial processes where small liquid drops containing thousands to millions of micron-size to colloidal-size particles are released over time from seepage or leaks into fractured rock. The behavior of these particle swarms as they fall under gravity are affected by particle interactions as well as interactions with the walls of the fractures. In this paper, we present experimental results on the effect of fractures on the cohesiveness of the swarm and the formation of bifurcation structures as they fall under gravity and interact with the fracture walls. A transparent cubic sample (100 mm x 100 mm x 100 mm) containing a synthetic fracture with uniform aperture distributions was optically imaged to quantify the effect of confinement within fractures on particle swarm formation, swarm velocity, and swarm geometry. A fracture with a uniform aperture distribution was fabricated from two polished rectangular prisms of acrylic. A series of experiments were performed to determine how swarm movement and geometry are affected as the walls of the fracture are brought closer together from 50 mm to 1 mm. During the experiments, the fracture was fully saturated with water. We created the swarms using two different particle sizes in dilute suspension (~ 1.0% by mass). The particles were 3 micron diameter fluorescent polymer beads and 25 micron diameter soda-lime glass beads. Experiments were performed using swarms that ranged in size from 5 µl to 60 µl. The swarm behavior was imaged using an optical fluorescent imaging system composed of a CCD camera illuminated by a 100 mW diode-pumped doubled YAG laser. As a swarm falls in an open-tank of water, it forms a torroidal shape that is stable as long as no ambient or background currents exist in the water tank. When a swarm is released into a fracture with an aperture less than 5 mm, the swarm forms the torroidal shape but it is distorted because of the presence of the walls. The

  19. Some Influences of Greek and Roman Rhetoric on Early Letter Writing.

    Science.gov (United States)

    Hildebrandt, Herbert W.

    1988-01-01

    Describes how letter writing, especially business letters, was influenced by Greek and Roman oral rhetoricians. Discusses three precepts of oral rhetoric--inventio, dispositio, and style--and notes that the classical theories' reflection in written communication can be seen in selected Italian, German, and English epistolographic works. (MM)

  20. Archaeometrical studies of Greek and Roman silver coins

    International Nuclear Information System (INIS)

    Bugoi, R.; Constantinescu, B.; Constantin, F.; Catana, D.; Plostinaru, D.

    1999-01-01

    Quantitative analyses of various silver coins from the firs century BC, found on current Romanian territory (Thasian tetradrachmae, Apollonia and Dyrrachium drachmae, Roman republican denarii) were performed using PIXE (3 MeV external proton beam) and XRF (1.1 GBq 241 Am source). The elemental analysis provided evidence of a great variety of monetary alloys and helped Romanian archaeologists to classify the coins, in terms of their provenance, as originals, copies or imitations minted in different areas of the Balkan-Carpathian region. (author)