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Sample records for accelerated artificial aging

  1. Color change of composite resins subjected to accelerated artificial aging.

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    Tornavoi, Denise Cremonezzi; Agnelli, José Augusto Marcondes; Panzeri, Heitor; Dos Reis, Andréa Cândido

    2013-01-01

    The aim of this study was to evaluate the influence of accelerated artificial aging (AAA) on the color change of composite resins used in dentistry. Three composite resins were evaluated: Two microhybrids and one hybrid of higher viscosity, with different amounts and sizes of filler particles, shades C2 and B2. A total of 54 specimens were obtained (18 for each composite resin), made of a Teflon matrix (15 mm in diameter and 2 mm in height). The color measurements were obtained with a Spectrophotometer, (PCB 6807 BYK Gardner) before and after AAA. Data were submitted to the Kolmogorov-Smirnov test (α >0.05), ANOVA and Tukey test (α 3). Considering the variable ∆E, it was observed that the color tone C2 was already statistically different for the microhybrid composite resin prior to AAA (P aging the composite resin hybrid of higher viscosity B2 showed the highest color variation rate and microhybrid with zirconium/silica C2 showed the lowest. All composite resins presented unacceptable color changes after 382 h of aging and different composite resins with same hue, presented different colors before being subjected to the aging process (B2 and C2) and after (B2). It was also observed color difference within a group of the same composite resin and same hue.

  2. Colour stability of denture teeth submitted to different cleaning protocols and accelerated artificial aging.

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    Freire, T S; Aguilar, F G; Garcia, L da Fonseca Roberti; Pires-de-Souza, F de Carvalho Panzeri

    2014-03-01

    Acrylic resin is widely used for artificial teeth manufacturing due to several important characteristics; however, this material do not present acceptable colour stability over the course of time. This study evaluated the effect of different cleaning protocols and accelerated artificial aging on colour stability of denture teeth made of acrylic resin. Sixty denture teeth in dark and light shades were used, and separated according to the treatment to which they were submitted. Results demonstrated that colour stability of artificial teeth is influenced by the cleaning solution and artificial aging, being dark teeth more susceptible to colour alteration than lighter ones.

  3. Influence of artificial accelerated aging on dimensional stability of acrylic resins submitted to different storage protocols.

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    Garcia, Lucas da Fonseca Roberti; Roselino, Lourenço de Moraes Rego; Mundim, Fabrício Mariano; Pires-de-Souza, Fernanda de Carvalho Panzeri; Consani, Simonides

    2010-08-01

    The aim of this study was to evaluate the influence of artificial accelerated aging on dimensional stability of two types of acrylic resins (thermally and chemically activated) submitted to different protocols of storage. One hundred specimens were made using a Teflon matrix (1.5 cm x 0.5 mm) with four imprint marks, following the lost-wax casting method. The specimens were divided into ten groups, according to the type of acrylic resin, aging procedure, and storage protocol (30 days). GI: acrylic resins thermally activated, aging, storage in artificial saliva for 16 hours, distilled water for 8 hours; GII: thermal, aging, artificial saliva for 16 hours, dry for 8 hours; GIII: thermal, no aging, artificial saliva for 16 hours, distilled water for 8 hours, GIV: thermal, no aging, artificial saliva for 16 hours, dry for 8 hours; GV: acrylic resins chemically activated, aging, artificial saliva for 16 hours, distilled water for 8 hours; GVI: chemical, aging, artificial saliva for 16 hours, dry for 8 hours; GVII: chemical, no aging, artificial saliva for 16 hours, distilled water for 8 hours; GVIII: chemical, no aging, artificial saliva for 16 hours, dry for 8 hours GIX: thermal, dry for 24 hours; and GX: chemical, dry for 24 hours. All specimens were photographed before and after treatment, and the images were evaluated by software (UTHSCSA - Image Tool) that made distance measurements between the marks in the specimens (mm), calculating the dimensional stability. Data were submitted to statistical analysis (two-way ANOVA, Tukey test, p= 0.05). Statistical analysis showed that the specimens submitted to storage in water presented the largest distance between both axes (major and minor), statistically different (p artificial accelerated aging and storage period influenced these alterations.

  4. Color change of composite resins subjected to accelerated artificial aging

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    Denise Cremonezzi Tornavoi

    2013-01-01

    Conclusions: All composite resins presented unacceptable color changes after 382 h of aging and different composite resins with same hue, presented different colors before being subjected to the aging process (B2 and C2 and after (B2. It was also observed color difference within a group of the same composite resin and same hue.

  5. Chromatic stability of acrylic resins of artificial eyes submitted to accelerated aging and polishing.

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    Goiato, Marcelo Coelho; Santos, Daniela Micheline dos; Souza, Josiene Firmino; Moreno, Amália; Pesqueira, Aldiéris Alves

    2010-12-01

    Esthetics and durability of materials used to fabricate artificial eyes has been an important issue since artificial eyes are essential to restore esthetics and function, protect the remaining tissues and help with patients' psychological therapy. However, these materials are submitted to degrading effects of environmental agents on the physical properties of the acrylic resin. This study assessed the color stability of acrylic resins used to fabricate sclera in three basic shades (N1, N2 and N3) when subjected to accelerated aging, mechanical and chemical polishing. Specimens of each resin were fabricated and submitted to mechanical and chemical polishing. Chromatic analysis was performed before and after accelerated aging through ultraviolet reflection spectrophotometry. All specimens revealed color alteration following polishing and accelerated aging. The resins presented statistically significant chromatic alteration (p<0.01) between the periods of 252 and 1008 h. Both polishing methods presented no significant difference between the values of color derivatives of resins.

  6. Influence of artificial accelerated aging on the color stability and opacity of composites of different shades.

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    Mundim, F M; Da Fonseca Roberti Garcia, L; Silva Sousa, A B; Cruvinel, D R; De Carvalho Panzeri Pires-De-Souza, F

    2010-10-01

    The aim of this study was to evaluate the influence of artificial accelerated aging on the color stability and opacity of composites of different shades. Four composites for direct use (Heliomolar, 4 Seasons, Tetric EvoCeram; QuiXfil) and one for indirect use (SR Adoro) in two shades were used: light (A2) and dark (C3 for direct, and D4 for indirect composite). QuiXfil was obtained in Universal shade. A Teflon matrix (12 X 2 mm) was used to obtain 54 specimens (N=6), which were submitted to color and opacity analysis (Spectrophotometer PCB 6807, Byk Gardner) before and after artificial accelerated aging for 384 hours. After the statistical analysis (2-way ANOVA - Bonferroni - PArtificial accelerated aging interfered in the optical properties assessed; however, the alterations seemed to be more related to the composites composition than to their shade.

  7. Colour stability of temporary restorations with different thicknesses submitted to artificial accelerated aging.

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    Silame, F D J; Tonani, R; Alandia-Roman, C C; Chinelatti, M; Panzeri, H; Pires-de-Souza, F C P

    2013-12-01

    This study evaluated the colour stability of temporary prosthetic restorations with different thicknesses submitted to artificial accelerated aging. The occlusal surfaces of 40 molars were grinded to obtain flat enamel surfaces. Twenty acrylic resin specimens [Polymethyl methacrylate (Duralay) and Bis-methyl acrylate (Luxatemp)] were made with two different thicknesses, 0.5 mm and 1.0 mm. Temporary restorations were fixed on enamel and CIE L*a*b* colour parameters of each specimen were assessed before and after artificial accelerated aging. All groups showed colour alterations above the clinically acceptable limit. Luxatemp showed the lowest colour alteration regardless its thickness and Duralay showed the greatest alteration with 0.5 mm.

  8. Assessment of surface hardness of acrylic resins submitted to accelerated artificial aging.

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    Tornavoi, D C; Agnelli, J A M; Lepri, C P; Mazzetto, M O; Botelho, A L; Soares, R G; Dos Reis, A C

    2012-06-01

    The aim of this study was to assess the influence of accelerated artificial aging (AAA) on the surface hardness of acrylic resins. The following three commercial brands of acrylic resins were tested: Vipi Flash (autopolymerized resin), Vipi Wave (microwave heat-polymerized resin) and Vipi Cril (conventional heat-polymerized resin). To perform the tests, 21 test specimens (65x10x3 mm) were made, 7 for each resin. Three surface hardness readings were performed for each test specimen, before and after AAA, and the means were submitted to the following tests: Kolmogorov-Smirnov (P>0.05), Levene Statistic, Two-way ANOVA, Tukey Post Hoc (Paging, the autopolymerized acrylic resin Vipi Flash showed lower hardness values when compared with the heat-polymerized resin Vipi Cril (P=0.001). After aging, the 3 materials showed similar performance when compared among them. The Vipi Cril was the only one affected by AAA and showed lower hardness values after this procedure (Pp=0.003). It may be concluded that accelerated artificial aging influenced surface hardness of heat-polymerized acrylic resin Vipi Cril.

  9. Analysis of the microstructure and mechanical performance of composite resins after accelerated artificial aging.

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    De Oliveira Daltoé, M; Lepri, C Penazzo; Wiezel, J Guilherme G; Tornavoi, D Cremonezzi; Agnelli, J A Marcondes; Reis, A Cândido Dos

    2013-03-01

    Researches that assess the behavior of dental materials are important for scientific and industrial development especially when they are tested under conditions that simulate the oral environment, so this work analyzed the compressive strength and microstructure of three composite resins subjected to accelerated artificial aging (AAA). Three composites resins of 3M (P90, P60 and Z100) were analyzed and were obtained 16 specimens for each type (N.=48). Half of each type were subjected to UV-C system AAA and then were analyzed the surfaces of three aged specimens and three not aged of each type through the scanning electron microscope (SEM). After, eight specimens of each resin, aged and not aged, were subjected to compression test. After statistical analysis of compressive strength values, it was found that there was difference between groups (α aged P60 presented lower values of compressive strength statistically significant when compared to the not subject to the AAA. For the other composite resins, there was no difference, regardless of aging, a fact confirmed by SEM. The results showed that the AAA influenced the compressive strength of the resin aged P60; confirmed by surface analysis by SEM, which showed greater structural disarrangement on surface material.

  10. Accelerated artificial aging of particleboards from residues of CCB treated Pinus sp. and castor oil resin

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    Marília da Silva Bertolini

    2013-04-01

    Full Text Available Tests simulating exposure to severe weather conditions have been relevant in seeking new applications for particleboard. This study aimed to produce particleboards with residues of CCB (chromium-copper-boron oxides impregnated Pinus sp. and castor oil-based polyurethane resin, and to evaluate their performance before and after artificial accelerated aging. Panels were produced with different particle mass, resin content and pressing time, resulting eight treatments. Particles moisture and size distribution were determined, beyond panel physical and mechanical properties, according to NBR14810-3: 2006. After characterization, treatments B and G (small adhesive consumption and better mechanical performance, respectively were chosen to artificial aging tests. Statistical results analysis showed best performances were achieved for waterproof aged samples, of both B and G treatments. As example, in treatment B, MOR and MOE values were 23 MPa and 2,297 MPa, samples before exposure; 26 MPa and 3,185 MPa, 32 MPa and 3,982 MPa for samples after exposure (non-sealed and sealed, respectively.

  11. Color Stability of CAD/CAM Fabricated Inlays after Accelerated Artificial Aging.

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    Karaokutan, Isil; Yilmaz Savas, Tuba; Aykent, Filiz; Ozdere, Eda

    2016-08-01

    To investigate the influence of accelerated artificial aging on the color stability of three different inlay restorations produced with a CAD/CAM system. Thirty non-carious human mandibular molar teeth were used. The teeth were embedded in autopolymerizing acrylic resin blocks. Standard Class I inlay cavities were prepared, and the teeth were randomly divided into three groups (n = 10) to fabricate inlay restorations: (1) a feldspathic-ceramic group, (2) a resin nano-ceramic group, and (3) a leucite glass-ceramic group. Optical impressions were made with CEREC software, and the restorations were designed and then milled. The inlays were adhesively cemented with a dual-polymerizing resin cement and left in distilled water at room temperature for 1 week. Color measurements were performed with a spectrophotometer before and after accelerated aging in a weathering machine with a total energy of 150 kJ/m(2) . Changes in color (∆E, ∆L, ∆a, ∆b, ∆C) were determined using the CIE L*a*b* system. The results were assessed using a one-way ANOVA and Tukey's HSD test (p = 0.05). The color changes of the materials ranged from 2.1 to 9.29. The highest color change was seen in the resin nano-ceramic material. This change was not clinically acceptable (∆E > 5.5). No significant differences were found in the ∆L and ∆a values of the test groups. Color changes were observed in each evaluated material after accelerated aging. All CAD/CAM inlays became darker in appearance, more saturated, a little reddish, and more yellow. © 2015 by the American College of Prosthodontists.

  12. Microstructure and mechanical properties of composite resins subjected to accelerated artificial aging.

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    dos Reis, Andréa Cândido; de Castro, Denise Tornavoi; Schiavon, Marco Antônio; da Silva, Leandro Jardel; Agnelli, José Augusto Marcondes

    2013-01-01

    The aim of this study was to investigate the influence of accelerated artificial aging (AAA) on the microstructure and mechanical properties of the Filtek Z250, Filtek Supreme, 4 Seasons, Herculite, P60, Tetric Ceram, Charisma and Filtek Z100. composite resins. The composites were characterized by Fourier-transform Infrared spectroscopy (FTIR) and thermal analyses (Differential Scanning Calorimetry - DSC and Thermogravimetry - TG). The microstructure of the materials was examined by scanning electron microscopy. Surface hardness and compressive strength data of the resins were recorded and the mean values were analyzed statistically by ANOVA and Tukey's test (α=0.05). The results showed significant differences among the commercial brands for surface hardness (F=86.74, p<0.0001) and compressive strength (F=40.31, p<0.0001), but AAA did not affect the properties (surface hardness: F=0.39, p=0.53; compressive strength: F=2.82, p=0.09) of any of the composite resins. FTIR, DSC and TG analyses showed that resin polymerization was complete, and there were no differences between the spectra and thermal curve profiles of the materials obtained before and after AAA. TG confirmed the absence of volatile compounds and evidenced good thermal stability up to 200 °C, and similar amounts of residues were found in all resins evaluated before and after AAA. The AAA treatment did not significantly affect resin surface. Therefore, regardless of the resin brand, AAA did not influence the microstructure or the mechanical properties.

  13. Effect of Accelerated Artificial Aging on Translucency of Methacrylate and Silorane-Based Composite Resins.

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    Shirinzad, Mehdi; Rezaei-Soufi, Loghman; Mirtorabi, Maryam Sadat; Vahdatinia, Farshid

    2016-03-01

    Composite restorations must have tooth-like optical properties namely color and translucency and maintain them for a long time. This study aimed to compare the effect of accelerated artificial aging (AAA) on the translucency of three methacrylate-based composites (Filtek Z250, Filtek Z250XT and Filtek Z350XT) and one silorane-based composite resin (Filtek P90). For this in vitro study, 56 composite discs were fabricated (n=14 for each group). Using scanning spectrophotometer, CIE L*a*b* parameters and translucency of each specimen were measured at 24 hours and after AAA for 384 hours. Data were analyzed using one-way ANOVA, Tukey's test and paired t-test at P=0.05 level of significance. The mean (±standard deviation) translucency parameter for Filtek Z250, Filtek Z250XT, Filtek Z350XT and Filtek P90 was 5.67±0.64, 4.59±0.77, 7.87±0.82 and 4.21±0.71 before AAA and 4.25±0.615, 3.53±0.73, 5.94±0.57 and 4.12±0.54 after AAA, respectively. After aging, the translucency of methacrylate-based composites decreased significantly (P0.05). The AAA significantly decreased the translucency of methacrylate-based composites (Filtek Z250, Filtek Z250XT and Filtek Z350XT) but no change occurred in the translucency of Filtek P90 silorane-based composite.

  14. Effects of different surface treatments and accelerated artificial aging on the bond strength of composite resin repairs.

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    Melo, Marco Aurélio Veiga de; Moysés, Marcos Ribeiro; Santos, Saulo Galvão dos; Alcântara, Carlos Eduardo Pinto; Ribeiro, José Carlos Rabelo

    2011-01-01

    The purpose of the present study was to assess the bond strength of composite resin repairs subjected to different surface treatments and accelerated artificial aging. 192 cylindrical samples (CSs) were prepared and divided into 24 groups (n = 8). Half of the CSs were stored in water for 24 h, and the other half were subjected to C-UV accelerated aging for non-metallic specimens. The treatments were phosphoric acid + silane + adhesive (PSA); phosphoric acid + adhesive (PA); diamond bur + phosphoric acid + silane + adhesive (DPSA); diamond bur + phosphoric acid + adhesive (DPA); air abrasion + phosphoric acid + silane + adhesive (APSA); and air abrasion + phosphoric acid + adhesive (APA). The repair was performed and the specimens were again aged as described above. A control group (n = 8) was established and did not receive any type of aging or surface treatment. The specimens were loaded to failure in shear mode with a crosshead speed of 0.5 mm/min until fracture. Data were analyzed by one-way ANOVA/Tukey's test (p aged PSA and PA achieved low bonding values and were statistically different from the control group, whereas the non-aged PSA and PA presented no statistically significant difference from the control group. Repairs with the proposed surface treatments were viable on both recent and aged restorations; however, phosphoric acid + adhesive alone were effective only on recent restorations.

  15. Effects of different surface treatments and accelerated artificial aging on the bond strength of composite resin repairs

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    Marco Aurélio Veiga de Melo

    2011-12-01

    Full Text Available The purpose of the present study was to assess the bond strength of composite resin repairs subjected to different surface treatments and accelerated artificial aging. 192 cylindrical samples (CSs were prepared and divided into 24 groups (n = 8. Half of the CSs were stored in water for 24 h, and the other half were subjected to C-UV accelerated aging for non-metallic specimens. The treatments were phosphoric acid + silane + adhesive (PSA; phosphoric acid + adhesive (PA; diamond bur + phosphoric acid + silane + adhesive (DPSA; diamond bur + phosphoric acid + adhesive (DPA; air abrasion + phosphoric acid + silane + adhesive (APSA; and air abrasion + phosphoric acid + adhesive (APA. The repair was performed and the specimens were again aged as described above. A control group (n = 8 was established and did not receive any type of aging or surface treatment. The specimens were loaded to failure in shear mode with a crosshead speed of 0.5 mm/min until fracture. Data were analyzed by one-way ANOVA/Tukey's test (p < 0.05. No statistically significant differences were found among DPSA, DPA, APSA, APA, and the control group. The aged PSA and PA achieved low bonding values and were statistically different from the control group, whereas the non-aged PSA and PA presented no statistically significant difference from the control group. Repairs with the proposed surface treatments were viable on both recent and aged restorations; however, phosphoric acid + adhesive alone were effective only on recent restorations.

  16. Color and opacity of composites protected with surface sealants and submitted to artificial accelerated aging.

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    Aguilar, Fabiano Gamero; Roberti Garcia, Lucas da Fonseca; Cruvinel, Diogo Rodrigues; Sousa, Ana Beatriz Silva; de Carvalho Panzeri Pires-de-Souza, Fernanda

    2012-01-01

    To evaluate the color similarity, stability and opacity of composites (TPH, Charisma, and Concept, shade A2) protected with surface sealants (Fortify Plus and Biscover) and cyanoacrylate (Super Bonder). Forty specimens of each composite were made and separated into 4 groups (n=10) according to the surface protection: GI - without sealant; GII - cyanoacrylate; GIII - Fortify Plus; GIV - Biscover. Color and opacity readings were taken before and after Artificial Acelerated Aging (AAA) and the values obtained for color stability were submitted to statistical analysis by 2-way ANOVA and Bonferroni's test (P<.05). The values acquired for color similarity were submitted to 1-way ANOVA and Tukey's test (P<.05). The specimen sufaces were compared before and after AAA using Scanning Electronic Microscopy (SEM). Studied composites did not present the same values for the coordinates L*, a* and b * before AAA, indicating that there was no color similarity among them. All composites presented color alteration after AAA with clinically unacceptable values. Protected groups presented lower opacity variation after AAA, in comparison with the control goup. SEM evaluation demonstrated that AAA increased the surface irregularities in all of the studied groups. Surface sealants were not effective in maintaining composite color, but were able to maintain opacity.

  17. Artificial seismic acceleration

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    Felzer, Karen R.; Page, Morgan T.; Michael, Andrew J.

    2015-01-01

    In their 2013 paper, Bouchon, Durand, Marsan, Karabulut, 3 and Schmittbuhl (BDMKS) claim to see significant accelerating seismicity before M 6.5 interplate mainshocks, but not before intraplate mainshocks, reflecting a preparatory process before large events. We concur with the finding of BDMKS that their interplate dataset has significantly more fore- shocks than their intraplate dataset; however, we disagree that the foreshocks are predictive of large events in particular. Acceleration in stacked foreshock sequences has been seen before and has been explained by the cascade model, in which earthquakes occasionally trigger aftershocks larger than themselves4. In this model, the time lags between the smaller mainshocks and larger aftershocks follow the inverse power law common to all aftershock sequences, creating an apparent acceleration when stacked (see Supplementary Information).

  18. Bleaching agent action on color stability, surface roughness and microhardness of composites submitted to accelerated artificial aging.

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    Rattacaso, Raphael Mendes Bezerra; da Fonseca Roberti Garcia, Lucas; Aguilar, Fabiano Gamero; Consani, Simonides; de Carvalho Panzeri Pires-de-Souza, Fernanda

    2011-04-01

    The purpose of this study was to evaluate the bleaching agent action on color stability, surface roughness and microhardness of composites (Charisma, Filtek Supreme and Heliomolar - A2) submitted to accelerated artificial aging (AAA). A Teflon matrix (12 x 2 mm) was used to fabricate 18 specimens (n=6) which, after polishing (Sof-Lex), were submitted to initial color reading (ΔE), Knoop microhardness (KHN) (50 g/15 s load) and roughness (R(a)) (cut-off 0.25 mm) tests. Afterwards, the samples were submitted to AAA for 384 hours and new color, microhardness and roughness readings were performed. After this, the samples were submitted to daily application (4 weeks) of 16% Carbamide Peroxide (NiteWhite ACP) for 8 hours and kept in artificial saliva for 16 hours. New color, microhardness and roughness readings were made at the end of the cycle, and 15 days after bleaching. Comparison of the ΔE means (2-way ANOVA, Bonferroni, P<.05) indicated clinically unacceptable color alteration for all composites after AAA, but without significant difference. Statistically significant increase in the KHN values after AAA was observed, but without significant alterations 15 days after bleaching. For R(a) there was no statistically significant difference after AAA and 15 days after bleaching. The alterations promoted by the bleaching agent and AAA are material dependent.

  19. Effect of artificial accelerated aging on the optical properties and monomeric conversion of composites used after expiration date.

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    Garcia, Lucas da Fonseca Roberti; Mundim, Fabricio Mariano; Pires-de-Souza, Fernanda de Carvalho Panzeri; Puppin Rontani, Regina Maria; Consani, Simonides

    2013-01-01

    This study sought to evaluate how artificial accelerated aging (AAA) affected color stability (ΔE), opacity (ΔOP), and degree of conversion (DOC) for 3 composite materials (Tetric Ceram, Tetric Ceram HB, and Tetric Flow) used both 180 days before and 180 days after their expiration dates. To evaluate the materials' optical properties, 10 specimens of each composite-5 prior to expiration and 5 after the materials' expiration date-were made in a teflon matrix. After polishing, the specimens were submitted to initial color and opacity readings and submitted to AAA for 384 hours; at that point, new readings were taken to determine ΔE and ΔOP. To evaluate monomeric conversion evaluation, 6 specimens from each composite and expiration date-3 prior to AAA and 3 after-were submitted to DOC analysis. Results of the 2-way ANOVA and Bonferroni's tests (P 0.05). The expired Tetric Flow had the highest DOC values (71.42% ± 4.21) before AAA, significantly different than that of the other composites (P > 0.05). It was concluded that both expiration date and AAA affected the properties of the composites tested.

  20. Influence of finishing/polishing on color stability and surface roughness of composites submitted to accelerated artificial aging

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    Gustavo Da Col dos Santos Pinto

    2013-01-01

    Full Text Available Aim: To assess the influence of finishing/polishing procedure on color stability (ΔE and surface roughness (Ra of composites (Heliomolar and Tetric - color A2 submitted to accelerated artificial aging (AAA. Materials and Methods : Sixty test specimens were made of each composite (12 mm × 2 mm and separated into six groups (n = 10, according to the type of finishing/polishing to which they were submitted: C, control; F, tip 3195 F; FF, tip 3195 FF; FP, tip 3195 F + diamond paste; FFP, tip 3195 FF + diamond paste; SF, Sof-Lex discs. After polishing, controlled by an electromechanical system, initial color (spectrophotometer PCB 6807 BYK GARDNER and Ra (roughness meter Surfcorder SE 1700, cut-off 0.25 mm readings were taken. Next, the test specimens were submitted to the AAA procedure (C-UV Comexim for 384 hours, and at the end of this period, new color readings and R a were taken. Results: Statistical analysis [2-way analysis of variance (ANOVA, Bonferroni, P < 0.05] showed that all composites demonstrated ΔE alteration above the clinically acceptable limits, with the exception of Heliomolar composite in FP. The greatest ΔE alteration occurred for Tetric composite in SF (13.38 ± 2.10 statistically different from F and FF (P < 0.05. For Ra , Group F showed rougher samples than FF with statistically significant difference (P < 0.05. Conclusion: In spite of the surface differences, the different finishing/polishing procedures were not capable of providing color stability within the clinically acceptable limits.

  1. Influence of finishing/polishing on color stability and surface roughness of composites submitted to accelerated artificial aging.

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    Pinto, Gustavo Da Col dos Santos; Dias, Kleber Campioni; Cruvinel, Diogo Rodrigues; Garcia, Lucas da Fonseca Roberti; Consani, Simonides; Pires-De-Souza, Fernanda de Carvalho Panzeri

    2013-01-01

    To assess the influence of finishing/polishing procedure on color stability (ΔE ) and surface roughness (R(a)) of composites (Heliomolar and Tetric - color A2) submitted to accelerated artificial aging (AAA). Sixty test specimens were made of each composite (12 mm × 2 mm) and separated into six groups (n = 10), according to the type of finishing/polishing to which they were submitted: C, control; F, tip 3195 F; FF, tip 3195 FF; FP, tip 3195 F + diamond paste; FFP, tip 3195 FF + diamond paste; SF, Sof-Lex discs. After polishing, controlled by an electromechanical system, initial color (spectrophotometer PCB 6807 BYK GARDNER) and R(a) (roughness meter Surfcorder SE 1700, cut-off 0.25 mm) readings were taken. Next, the test specimens were submitted to the AAA procedure (C-UV Comexim) for 384 hours, and at the end of this period, new color readings and R(a) were taken. Statistical analysis [2-way analysis of variance (ANOVA), Bonferroni, P < 0.05] showed that all composites demonstrated ΔE alteration above the clinically acceptable limits, with the exception of Heliomolar composite in FP. The greatest ΔE alteration occurred for Tetric composite in SF (13.38 ± 2.10) statistically different from F and FF (P < 0.05). For R(a), Group F showed rougher samples than FF with statistically significant difference (P < 0.05). In spite of the surface differences, the different finishing/polishing procedures were not capable of providing color stability within the clinically acceptable limits.

  2. Effect of Instrumentation Techniques, Irrigant Solutions and Artificial accelerated Aging on Fiberglass Post Bond Strength to Intraradicular Dentin.

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    Santana, Fernanda Ribeiro; Soares, Carlos José; Silva, Júlio Almeida; Alencar, Ana Helena Gonçalves; Renovato, Sara Rodrigues; Lopes, Lawrence Gonzaga; Estrela, Carlos

    2015-07-01

    To evaluate the effect of instrumentation techniques, irrigant solutions and specimen aging on fiberglass posts bond strength to intraradicular dentine. A total of 120 bovine teeth were prepared and randomized into control and experimental groups resulting from three study factors (instrumentation techniques, irrigant solutions, specimen aging). Posts were cemented with RelyX U100. Samples were submitted to push-out test and failure mode was evaluated under a confocal microscope. In specimens submitted to water artificial aging, nickel-titanium rotary instruments group presented higher bond strength values in apical third irrigated with NaOCl or chlorhexi-dine. Irrigation with NaOCl resulted in higher bond strength than ozonated water. Artificial aging resulted in significant bond strength increase. Adhesive cement-dentin failure was prevalent in all the groups. Root canal preparation with NiTi instruments associated with NaOCl irrigation and ethylenediaminetetra acetic acid (EDTA) increased bond strength of fiberglass posts cemented with self-adhesive resin cement to intraradicular dentine. Water artificial aging significantly increased post-Clinical significance: The understanding of factors that may influence the optimal bond between post-cement and cement-dentin are essential to the success of endodontically treated tooth restoration.

  3. Effects of accelerated artificial daylight aging on bending strength and bonding of glass fibers in fiber-embedded maxillofacial silicone prostheses.

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    Hatamleh, Muhanad M; Watts, David C

    2010-07-01

    The purpose of this study was to test the effect of different periods of accelerated artificial daylight aging on bond strength of glass fiber bundles embedded into maxillofacial silicone elastomer and on bending strength of the glass fiber bundles. Forty specimens were fabricated by embedding resin-impregnated fiber bundles (1.5-mm diameter, 20-mm long) into maxillofacial silicone elastomer. Specimens were randomly allocated into four groups, and each group was subjected to different periods of accelerated daylight aging as follows (in hours); 0, 200, 400, and 600. The aging cycle included continuous exposure to quartz-filtered visible daylight (irradiance 760 W/m(2)) under an alternating weathering cycle (wet for 18 minutes, dry for 102 minutes). Pull-out tests were performed to evaluate bond strength between fiber bundles and silicone using a universal testing machine at 1 mm/min crosshead speed. Also a three-point bending test was performed to evaluate bending strength of the fiber bundles. One-way ANOVA and Bonferroni post hoc tests were carried out to detect statistical significance (p aging only. After 200 hours of exposure to artificial daylight and moisture conditions, bond strength between glass fibers and heat-cured silicones is optimal, and the bending strength of the glass fiber bundles is enhanced.

  4. Influence of Different Types of Resin Luting Agents on Color Stability of Ceramic Laminate Veneers Subjected to Accelerated Artificial Aging.

    Science.gov (United States)

    Silami, Francisca Daniele Jardilino; Tonani, Rafaella; Alandia-Román, Carla Cecilia; Pires-de-Souza, Fernanda de Carvalho Panzeri

    2016-01-01

    The aim of this study was to evaluate the influence of accelerated aging (AAA) on the color stability of resin cements for bonding ceramic laminate veneers of different thicknesses. The occlusal surfaces of 80 healthy human molars were flattened. Ceramic laminate veneers (IPS e-max Ceram) of two thicknesses (0.5 and 1.0 mm) were bonded with three types of luting agents: light-cured, conventional dual and self-adhesive dual cement. Teeth without restorations and cement samples (0.5 mm) were used as control. After initial color evaluations, the samples were subjected to AAA for 580 h. After this, new color readouts were made, and the color stability (ΔE) and luminosity (ΔL) data were analyzed. The greatest color changes (p<0.05) occurred when 0.5 mm veneers were fixed with light-cured cement and the lowest when 1.0 mm veneers were fixed with conventional dual cement. There was no influence of the restoration thickness when the self-adhesive dual cement was used. When veneers were compared with the control groups, it was verified that the cement samples presented the greatest alterations (p<0.05) in comparison with both substrates and restored teeth. Therefore, it was concluded that the thickness of the restoration influences color and luminosity changes for conventional dual and light-cured cements. The changes in self-adhesive cement do not depend on restoration thickness.

  5. Menopause accelerates biological aging

    Science.gov (United States)

    Levine, Morgan E.; Lu, Ake T.; Chen, Brian H.; Hernandez, Dena G.; Singleton, Andrew B.; Ferrucci, Luigi; Bandinelli, Stefania; Salfati, Elias; Manson, JoAnn E.; Quach, Austin; Kusters, Cynthia D. J.; Kuh, Diana; Wong, Andrew; Teschendorff, Andrew E.; Widschwendter, Martin; Ritz, Beate R.; Absher, Devin; Assimes, Themistocles L.; Horvath, Steve

    2016-01-01

    Although epigenetic processes have been linked to aging and disease in other systems, it is not yet known whether they relate to reproductive aging. Recently, we developed a highly accurate epigenetic biomarker of age (known as the “epigenetic clock”), which is based on DNA methylation levels. Here we carry out an epigenetic clock analysis of blood, saliva, and buccal epithelium using data from four large studies: the Women's Health Initiative (n = 1,864); Invecchiare nel Chianti (n = 200); Parkinson's disease, Environment, and Genes (n = 256); and the United Kingdom Medical Research Council National Survey of Health and Development (n = 790). We find that increased epigenetic age acceleration in blood is significantly associated with earlier menopause (P = 0.00091), bilateral oophorectomy (P = 0.0018), and a longer time since menopause (P = 0.017). Conversely, epigenetic age acceleration in buccal epithelium and saliva do not relate to age at menopause; however, a higher epigenetic age in saliva is exhibited in women who undergo bilateral oophorectomy (P = 0.0079), while a lower epigenetic age in buccal epithelium was found for women who underwent menopausal hormone therapy (P = 0.00078). Using genetic data, we find evidence of coheritability between age at menopause and epigenetic age acceleration in blood. Using Mendelian randomization analysis, we find that two SNPs that are highly associated with age at menopause exhibit a significant association with epigenetic age acceleration. Overall, our Mendelian randomization approach and other lines of evidence suggest that menopause accelerates epigenetic aging of blood, but mechanistic studies will be needed to dissect cause-and-effect relationships further. PMID:27457926

  6. Effect of root canal sealer and artificial accelerated aging on fibreglass post bond strength to intraradicular dentin.

    Science.gov (United States)

    Santana, Fernanda-Ribeiro; Soares, Carlos-José; Ferreira, Josemar-Martins; Valdivi, Andréa-Dolores-Correia-Miranda; Souza, João-Batista-de; Estrela, Carlos

    2014-10-01

    To evaluate the effect of root canal sealers (RCS) and specimen aging on the bond strength of fibre posts to bovine intraradicular dentin. 80 teeth were used according the groups - Sealapextm, Sealer 26®, AH Plus® and specimens aging - test with no aging and with aging. The canals prepared were filled using one of each RCS. The posts were cemented. Roots were cross-sectioned to obtain two slices of each third. Samples were submitted to push-out test. Failure mode was evaluated under a confocal microscope. The data were analysed by ANOVA, Tukey's, and Dunnet tests (α = 0.05). No significant difference was detected among RCS. Aged control presented higher bond strength than immediate control. The aging did not result significant difference. Adhesive cement-dentin failure was prevalent in all groups. RCS interfered negatively with bonding of fibreglass posts cemented with self-adhesive resin cement to intraradicular dentin. Key words:Fibreglass post, bond strength, root dentin, endodontic sealer, aging.

  7. Accelerating artificial intelligence with reconfigurable computing

    Science.gov (United States)

    Cieszewski, Radoslaw

    Reconfigurable computing is emerging as an important area of research in computer architectures and software systems. Many algorithms can be greatly accelerated by placing the computationally intense portions of an algorithm into reconfigurable hardware. Reconfigurable computing combines many benefits of both software and ASIC implementations. Like software, the mapped circuit is flexible, and can be changed over the lifetime of the system. Similar to an ASIC, reconfigurable systems provide a method to map circuits into hardware. Reconfigurable systems therefore have the potential to achieve far greater performance than software as a result of bypassing the fetch-decode-execute operations of traditional processors, and possibly exploiting a greater level of parallelism. Such a field, where there is many different algorithms which can be accelerated, is an artificial intelligence. This paper presents example hardware implementations of Artificial Neural Networks, Genetic Algorithms and Expert Systems.

  8. Artificial intelligence approach to accelerator control systems

    International Nuclear Information System (INIS)

    Schultz, D.E.; Hurd, J.W.; Brown, S.K.

    1987-01-01

    An experiment was recently started at LAMPF to evaluate the power and limitations of using artificial intelligence techniques to solve problems in accelerator control and operation. A knowledge base was developed to describe the characteristics and the relationships of the first 30 devices in the LAMPF H+ beam line. Each device was categorized and pertinent attributes for each category defined. Specific values were assigned in the knowledge base to represent each actual device. Relationships between devices are modeled using the artificial intelligence techniques of rules, active values, and object-oriented methods. This symbolic model, built using the Knowledge Engineering Environment (KEE) system, provides a framework for analyzing faults, tutoring trainee operators, and offering suggestions to assist in beam tuning. Based on information provided by the domain expert responsible for tuning this portion of the beam line, additional rules were written to describe how he tunes, how he analyzes what is actually happening, and how he deals with failures. Initial results have shown that artificial intelligence techniques can be a useful adjunct to traditional methods of numerical simulation. Successful and efficient operation of future accelerators may depend on the proper merging of symbolic reasoning and conventional numerical control algorithms

  9. Physiological and proteomic analyses on artificially aged Brassica napus seed

    Directory of Open Access Journals (Sweden)

    Pingfang eYang

    2015-02-01

    Full Text Available Plant seeds lose their viability when they are exposed to long term storage or controlled deterioration treatments, by a process known as seed ageing. Based on previous studies, artificially ageing treatments have been developed to accelerate the process of seed ageing in order to understand its underlying mechanisms. In this study, we used Brassica napus seeds to investigate the mechanisms of ageing initiation. B. napus seeds were exposed to artificially ageing treatment (40 oC and 90% relative humidity and their physio-biochemical characteristics were analyzed. Although the treatment delayed germination, it did not increase the concentration of cellular reactive oxygen species (ROS. Comparative proteomic analysis was conducted among the control and treated seeds at different stages of germination. The proteins responded to the treatment were mainly involved in metabolism, protein modification and destination, stress response, development and miscellaneous enzymes. Except for peroxiredoxin, no changes were observed in the accumulation of other antioxidant enzymes in the artificially aged seeds. Increased content of ABA was observed in the artificially treated seeds which might be involved in the inhibition of germination. Taken together, our results highlight the involvement of ABA in the initiation of seed ageing in addition to the ROS which was previously reported to mediate the seed ageing process.

  10. A Review on Artificial Aging Behaviors of Fiber Reinforced Polymer-matrix Composites

    OpenAIRE

    Meng Jiangyan; Wang Yunying

    2016-01-01

    As is known, factors in climate environment such as hygrothermal effect and UV may have a negative effect on the mechanical properties of fiber reinforced polymer-matrix composites, resulting in their strength and stiffness degraded. In this review, we summarize all the recent studies on the artificial climate aging, hygrothermal aging, and thermal-oxidation aging of fiber reinforced polymer-matrix composites, as well as their artificial accelerated aging and natural aging. In addition, studi...

  11. An artificial intelligence approach to accelerator control systems

    International Nuclear Information System (INIS)

    Schultz, D.E.; Hurd, J.W.; Brown, S.K.

    1987-01-01

    An experiment was recently started at LAMPF to evaluate the power and limitations of using artificial intelligence techniques to solve problems in accelerator control and operation. A knowledge base was developed to describe the characteristics and the relationships of the first 30 devices in the LAMPF H+ beam line. Each device was categorized and pertinent attributes for each category defined. Specific values were assigned in the knowledge base to represent each actual device. Relationships between devices are modeled using the artificial intelligence techniques of rules, active values, and object-oriented methods. This symbolic model, built using the Knowledge Engineering Environment (KEE) system, provides a framework for analyzing faults, tutoring trainee operators, and offering suggestions to assist in beam tuning. Based on information provided by the domain expert responsible for tuning this portion of the beam line, additional rules were written to describe how he tunes, how he analyzes what is actually happening, and how he deals with failures. Initial results have shown that artificial intelligence techniques can be a useful adjunct to traditional methods of numerical simulation. Successful and efficient operation of future accelerators may depend on the proper merging of symbolic reasoning and conventional numerical control algorithms

  12. Analysis of surface hardness of artificially aged resin composites

    Directory of Open Access Journals (Sweden)

    Denise Cremonezzi Tornavoi

    2012-02-01

    Full Text Available This study evaluated the effect of artificially accelerated aging (AAA on the surface hardness of eight composite resins: Filtek Z250, Filtek Supreme, 4 Seasons, Herculite, P60, Tetric Ceram, Charisma, and Filtek Z100. Sixteen specimens were made from the test piece of each material, using an 8.0 × 2.0 mm teflon matrix. After 24 hours, eight specimens from each material were submitted to three surface hardness readings using a Shimadzu Microhardness Tester for 5 seconds at a load of 50 gf. The other eight specimens remained in the artificially accelerated aging machine for 382 hours and were submitted to the same surface hardness analysis. The means of each test specimen were submitted to the Kolmogorov-Smirnov test (p > 0.05, ANOVA and Tukey test (p < 0.05. With regard to hardness (F = 86.74, p < 0.0001 the analysis showed significant differences among the resin composite brands. But aging did not influence the hardness of any of the resin composites (F = 0.39, p = 0.53. In this study, there was interaction between the resin composite brand and the aging factors (F = 4.51, p < 0.0002. It was concluded that notwithstanding the type of resin, AAA did not influence surface hardness. However, with regard to hardness there was a significant difference among the resin brands.

  13. STUDY OF DURATION INFLUENCE OF ARTIFICIAL AGING ON THE PROPERTIES OF STEEL

    OpenAIRE

    Ms. Irina L. Polyanskaya; Ms. Nina V. Filisyuk

    2016-01-01

    The article presents the studies of artificial strain aging of pipe steels. Changes in temperature accelerate the aging process, which resulted in a change of its microstructure. The effect of strain aging on the mechanical properties of the steel in toughness tests is determined.

  14. Phase transformation of dental zirconia following artificial aging.

    Science.gov (United States)

    Lucas, Thomas J; Lawson, Nathaniel C; Janowski, Gregg M; Burgess, John O

    2015-10-01

    Low-temperature degradation (LTD) of yttria-stabilized zirconia can produce increased surface roughness with a concomitant decrease in strength. This study determined the effectiveness of artificial aging (prolonged boiling/autoclaving) to induce LTD of Y-TZP (yttria-tetragonal zirconia-polycrystals) and used artificial aging for transformation depth progression analyses. The null hypothesis is aging techniques tested produce the same amount of transformation, transformation is not time/temperature dependent and LTD causes a constant transformation throughout the Y-TZP samples. Dental-grade Y-TZP samples were randomly divided into nine subgroups (n = 5): as received, 3.5 and 7 day boiling, 1 bar autoclave (1, 3, 5 h), and 2 bar autoclave (1, 3, 5 h). A 4-h boil treatment (n = 2) was performed post-experiment for completion of data. Transformation was measured using traditional X-ray diffraction and low-angle X-ray diffraction. The fraction of t → m transformation increased with aging time. The 3.5 day boil and 2 bar 5 h autoclave produced similar transformation results, while the 7 day boiling treatment revealed the greatest transformation. The surface layer of the aged specimen underwent the most transformation while all samples displayed decreasing transformation with depth. Surface transformation was evident, which can lead to rougher surfaces and increased wear of opposing dentition/materials. Therefore, wear studies addressing LTD of Y-TZP are needed utilizing accelerated aging. © 2014 Wiley Periodicals, Inc.

  15. The potential of artificial aging for modelling of natural aging processes of ballpoint ink.

    Science.gov (United States)

    Weyermann, Céline; Spengler, Bernhard

    2008-08-25

    Artificial aging has been used to reproduce natural aging processes in an accelerated pace. Questioned documents were exposed to light or high temperature in a well-defined manner in order to simulate an increased age. This may be used to study the aging processes or to date documents by reproducing their aging curve. Ink was studied especially because it is deposited on the paper when a document, such as a contract, is produced. Once on the paper, aging processes start through degradation of dyes, solvents drying and resins polymerisation. Modelling of dye's and solvent's aging was attempted. These processes, however, follow complex pathways, influenced by many factors which can be classified as three major groups: ink composition, paper type and storage conditions. The influence of these factors is such that different aging states can be obtained for an identical point in time. Storage conditions in particular are difficult to simulate, as they are dependent on environmental conditions (e.g. intensity and dose of light, temperature, air flow, humidity) and cannot be controlled in the natural aging of questioned documents. The problem therefore lies more in the variety of different conditions a questioned document might be exposed to during its natural aging, rather than in the simulation of such conditions in the laboratory. Nevertheless, a precise modelling of natural aging curves based on artificial aging curves is obtained when performed on the same paper and ink. A standard model for aging processes of ink on paper is therefore presented that is based on a fit of aging curves to a power law of solvent concentrations as a function of time. A mathematical transformation of artificial aging curves into modelled natural aging curves results in excellent overlap with data from real natural aging processes.

  16. PETN Coarsening - Predictions from Accelerated Aging Data

    Energy Technology Data Exchange (ETDEWEB)

    Maiti, Amitesh [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Gee, Richard H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2011-03-30

    Ensuring good ignition properties over long periods of time necessitates maintaining a good level of porosity in powders of initiator materials and preventing particle coarsening. To simulate porosity changes of such powder materials over long periods of time a common strategy is to perform accelerated aging experiments over shorter time spans at elevated temperatures. In this paper we examine historical accelerated-aging data on powders of Pentaerythritol Tetranitrate (PETN), an important energetic material, and make predictions for long-term aging under ambient conditions. Lastly, we develop an evaporation-condensation- based model to provide some mechanistic understanding of the coarsening process.

  17. NASA FDL: Accelerating Artificial Intelligence Applications in the Space Sciences.

    Science.gov (United States)

    Parr, J.; Navas-Moreno, M.; Dahlstrom, E. L.; Jennings, S. B.

    2017-12-01

    NASA has a long history of using Artificial Intelligence (AI) for exploration purposes, however due to the recent explosion of the Machine Learning (ML) field within AI, there are great opportunities for NASA to find expanded benefit. For over two years now, the NASA Frontier Development Lab (FDL) has been at the nexus of bright academic researchers, private sector expertise in AI/ML and NASA scientific problem solving. The FDL hypothesis of improving science results was predicated on three main ideas, faster results could be achieved through sprint methodologies, better results could be achieved through interdisciplinarity, and public-private partnerships could lower costs We present select results obtained during two summer sessions in 2016 and 2017 where the research was focused on topics in planetary defense, space resources and space weather, and utilized variational auto encoders, bayesian optimization, and deep learning techniques like deep, recurrent and residual neural networks. The FDL results demonstrate the power of bridging research disciplines and the potential that AI/ML has for supporting research goals, improving on current methodologies, enabling new discovery and doing so in accelerated timeframes.

  18. Is biological aging accelerated in drug addiction?

    Science.gov (United States)

    Bachi, Keren; Sierra, Salvador; Volkow, Nora D; Goldstein, Rita Z; Alia-Klein, Nelly

    2017-02-01

    Drug-addiction may trigger early onset of age-related disease, due to drug-induced multi-system toxicity and perilous lifestyle, which remains mostly undetected and untreated. We present the literature on pathophysiological processes that may hasten aging and its relevance to addiction, including: oxidative stress and cellular aging, inflammation in periphery and brain, decline in brain volume and function, and early onset of cardiac, cerebrovascular, kidney, and liver disease. Timely detection of accelerated aging in addiction is crucial for the prevention of premature morbidity and mortality.

  19. Alteration of blue pigment in artificial iris in ocular prosthesis: effect of paint, drying method and artificial aging.

    Science.gov (United States)

    Goiato, Marcelo Coelho; Fernandes, Aline Úrsula Rocha; dos Santos, Daniela Micheline; Hadadd, Marcela Filié; Moreno, Amália; Pesqueira, Aldiéris Alves

    2011-02-01

    The artificial iris is the structure responsible for the dissimulation and aesthetics of ocular prosthesis. The objective of the present study was to evaluate the color stability of artificial iris of microwaveable polymerized ocular prosthesis, as a function of paint type, drying method and accelerated aging. A total of 40 discs of microwaveable polymerized acrylic resin were fabricated, and divided according to the blue paint type (n = 5): hydrosoluble acrylic, nitrocellulose automotive, hydrosoluble gouache and oil paints. Paints where dried either at natural or at infrared light bulb method. Each specimen was constituted of one disc in colorless acrylic resin and another colored with a basic sclera pigment. Painting was performed in one surface of one of the discs. The specimens were submitted to an artificial aging chamber under ultraviolet light, during 1008 h. A reflective spectrophotometer was used to evaluate color changes. Data were evaluated by 3-way repeated-measures ANOVA and the Tukey HSD test (α = 0.05). All paints suffered color alteration. The oil paint presented the highest color resistance to artificial aging regardless of drying method. Copyright © 2010 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  20. Insights into accelerated aging of SSL luminaires

    Science.gov (United States)

    Davis, J. Lynn; Lamvik, Michael; Bittle, James; Shepherd, Sarah; Yaga, Robert; Baldasaro, Nick; Solano, Eric; Bobashev, Georgiy

    2013-09-01

    Although solid-state lighting (SSL) products are often intended to have product lifetimes of 15 years or more, the rapid change in technology has created a need for accelerated life tests (ALTs) that can be performed in the span of several months. A critical element of interpreting results from any systems-level ALT is understanding of the impact of the test environment on each component. Because of its ubiquity in electronics, the use of temperature-humidity environments as potential ALTs for SSL luminaires was investigated. Results from testing of populations of three commercial 6" downlights in environments of 85°C and 85% relative humidity (RH) and 75°C and 75% RH are reported. These test environments were found to accelerate lumen depreciation of the entire luminaire optical system, including LEDs, lenses, and reflectors. The effects of aging were found to depend strongly on both the optical materials that were used and the design of the luminaire; this shows that the lumen maintenance behavior of SSL luminaires must be addressed at the optical systems level. Temperature-Humidity ALTs can be a useful test in understand lumainaire depreciation provided that proper consideration is given to the different aging rates of various materials. Since the impact of the temperature-humidity environment varies among components of the optical system, uniform aging of all system components in a single test is difficult to achieve.

  1. Accelerated Aging in Electrolytic Capacitors for Prognostics

    Science.gov (United States)

    Celaya, Jose R.; Kulkarni, Chetan; Saha, Sankalita; Biswas, Gautam; Goebel, Kai Frank

    2012-01-01

    The focus of this work is the analysis of different degradation phenomena based on thermal overstress and electrical overstress accelerated aging systems and the use of accelerated aging techniques for prognostics algorithm development. Results on thermal overstress and electrical overstress experiments are presented. In addition, preliminary results toward the development of physics-based degradation models are presented focusing on the electrolyte evaporation failure mechanism. An empirical degradation model based on percentage capacitance loss under electrical overstress is presented and used in: (i) a Bayesian-based implementation of model-based prognostics using a discrete Kalman filter for health state estimation, and (ii) a dynamic system representation of the degradation model for forecasting and remaining useful life (RUL) estimation. A leave-one-out validation methodology is used to assess the validity of the methodology under the small sample size constrain. The results observed on the RUL estimation are consistent through the validation tests comparing relative accuracy and prediction error. It has been observed that the inaccuracy of the model to represent the change in degradation behavior observed at the end of the test data is consistent throughout the validation tests, indicating the need of a more detailed degradation model or the use of an algorithm that could estimate model parameters on-line. Based on the observed degradation process under different stress intensity with rest periods, the need for more sophisticated degradation models is further supported. The current degradation model does not represent the capacitance recovery over rest periods following an accelerated aging stress period.

  2. The Third Age of Artificial Intelligence

    OpenAIRE

    Miailhe, Nicolas; Hodes, Cyrus

    2018-01-01

    If the definitional boundaries of Artificial Intelligence (AI) remains contested, experts agree that we are witnessing a revolution. “Is this time different?” is the question that they worryingly argue over when they analyze the socio-economic impact of the AI revolution as compared with the other industrial revolutions of the 19th and 20th centuries. This Schumpeterian wave may prove to be a creative destruction raising incomes, enhancing quality of life for all and generating previously uni...

  3. US particle accelerators at age 50

    International Nuclear Information System (INIS)

    Wilson, R.R.

    1981-01-01

    Fifty years ago, a dramatic race was under way to see who would be first to accelerate protons to an energy high enough to disintegrate the atomic nucleus. This contest, coincidental with the birth of the American Institute of Physics, could be considered as the beginning of what was to become a Golden age of high-energy physics. The race might also be taken to mark the end of an Age of Innocence of nulcear physicists. Heretofore during an era to which all physicists look back with nostalgia, much of the fundamental knowledge about the nucleus had been by obtained the use of rather primitive experimental devices, followed by sophisticated analysis. Rutherford's famous α-particle scattering experiment is a case-in-point: a little string and sealing wax and not much else. Not much, that is, except great leaps of reason and imagination. In the future, in addition to make-do skills, physicists were going to have to master arcane techniques, such as those of mechanical and electrical engineers. Indeed they would have to invent a whole new technology of accelerator building in order to explore the inside of the nucleus and to identify and study its constituent parts

  4. US particle accelerators at age 50

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, R.R.

    1981-11-01

    Fifty years ago, a dramatic race was under way to see who would be first to accelerate protons to an energy high enough to disintegrate the atomic nucleus. This contest, coincidental with the birth of the American Institute of Physics, could be considered as the beginning of what was to become a Golden age of high-energy physics. The race might also be taken to mark the end of an Age of Innocence of nulcear physicists. Heretofore during an era to which all physicists look back with nostalgia, much of the fundamental knowledge about the nucleus had been by obtained the use of rather primitive experimental devices, followed by sophisticated analysis. Rutherford's famous ..cap alpha..-particle scattering experiment is a case-in-point: a little string and sealing wax and not much else. Not much, that is, except great leaps of reason and imagination. In the future, in addition to make-do skills, physicists were going to have to master arcane techniques, such as those of mechanical and electrical engineers. Indeed they would have to invent a whole new technology of accelerator building in order to explore the inside of the nucleus and to identify and study its constituent parts.

  5. The coming of age of artificial intelligence in medicine

    OpenAIRE

    Patel, Vimla L.; Shortliffe, Edward H.; Stefanelli, Mario; Szolovits, Peter; Berthold, Michael R.; Bellazzi, Riccardo; Abu-Hanna, Ameen

    2009-01-01

    This paper is based on a panel discussion held at the Artificial Intelligence in Medicine Europe (AIME) conference in Amsterdam, The Netherlands, in July 2007. It had been more than 15 years since Edward Shortliffe gave a talk at AIME in which he characterized artificial intelligence (AI) in medicine as being in its “adolescence” (Shortliffe EH. The adolescence of AI in medicine: Will the field come of age in the ‘90s? Artificial Intelligence in Medicine 1993; 5:93–106). In this article, the ...

  6. Artificial Aging as a Predictor of Paper's Future Useful Life.

    Science.gov (United States)

    Bansa, Helmut; Hofer, Hans-H.

    1989-01-01

    An experiment with the artificial aging of paper which--in contrast with the usual practice--was carried out at relatively low temperatures (i.e., 50-95 degrees Celsius), and not on laboratory handsheets, but on naturally aged paper from the commercial production of four centuries, produced results justifying the thesis that there may be at best…

  7. Accelerated Aging of Polymer Composite Bridge Materials

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, Nancy Margaret; Blackwood, Larry Gene; Torres, Lucinda Laine; Rodriguez, Julio Gallardo; Yoder, Timothy Scott

    1999-03-01

    Accelerated aging research on samples of composite material and candidate ultraviolet (UV) protective coatings is determining the effects of six environmental factors on material durability. Candidate fastener materials are being evaluated to determine corrosion rates and crevice corrosion effects at load-bearing joints. This work supports field testing of a 30-ft long, 18-ft wide polymer matrix composite (PMC) bridge at the Idaho National Engineering and Environmental Laboratory (INEEL). Durability results and sensor data from tests with live loads provide information required for determining the cost/benefit measures to use in life-cycle planning, determining a maintenance strategy, establishing applicable inspection techniques, and establishing guidelines, standards, and acceptance criteria for PMC bridges for use in the transportation infrastructure.

  8. Accelerated Aging Experiments for Capacitor Health Monitoring and Prognostics

    Data.gov (United States)

    National Aeronautics and Space Administration — This paper discusses experimental setups for health monitoring and prognostics of electrolytic capacitors under nominal operation and accelerated aging conditions....

  9. Artificial acceleration of mammalian cell reprogramming by bacterial proteins.

    Science.gov (United States)

    Ikeda, Takashi; Uchiyama, Ikuo; Iwasaki, Mio; Sasaki, Tetsuhiko; Nakagawa, Masato; Okita, Keisuke; Masui, Shinji

    2017-10-01

    The molecular mechanisms of cell reprogramming and differentiation involve various signaling factors. Small molecule compounds have been identified to artificially influence these factors through interacting cellular proteins. Although such small molecule compounds are useful to enhance reprogramming and differentiation and to show the mechanisms that underlie these events, the screening usually requires a large number of compounds to identify only a very small number of hits (e.g., one hit among several tens of thousands of compounds). Here, we show a proof of concept that xenospecific gene products can affect the efficiency of cell reprogramming to pluripotency. Thirty genes specific for the bacterium Wolbachia pipientis were forcibly expressed individually along with reprogramming factors (Oct4, Sox2, Klf4 and c-Myc) that can generate induced pluripotent stem cells in mammalian cells, and eight were found to affect the reprogramming efficiency either positively or negatively (hit rate 26.7%). Mechanistic analysis suggested one of these proteins interacted with cytoskeleton to promote reprogramming. Our results raise the possibility that xenospecific gene products provide an alternative way to study the regulatory mechanism of cell identity. © 2017 Molecular Biology Society of Japan and John Wiley & Sons Australia, Ltd.

  10. The coming of age of artificial intelligence in medicine.

    Science.gov (United States)

    Patel, Vimla L; Shortliffe, Edward H; Stefanelli, Mario; Szolovits, Peter; Berthold, Michael R; Bellazzi, Riccardo; Abu-Hanna, Ameen

    2009-05-01

    This paper is based on a panel discussion held at the Artificial Intelligence in Medicine Europe (AIME) conference in Amsterdam, The Netherlands, in July 2007. It had been more than 15 years since Edward Shortliffe gave a talk at AIME in which he characterized artificial intelligence (AI) in medicine as being in its "adolescence" (Shortliffe EH. The adolescence of AI in medicine: will the field come of age in the '90s? Artificial Intelligence in Medicine 1993;5:93-106). In this article, the discussants reflect on medical AI research during the subsequent years and characterize the maturity and influence that has been achieved to date. Participants focus on their personal areas of expertise, ranging from clinical decision-making, reasoning under uncertainty, and knowledge representation to systems integration, translational bioinformatics, and cognitive issues in both the modeling of expertise and the creation of acceptable systems.

  11. The Coming of Age of Artificial Intelligence in Medicine*

    Science.gov (United States)

    Patel, Vimla L.; Shortliffe, Edward H.; Stefanelli, Mario; Szolovits, Peter; Berthold, Michael R.; Bellazzi, Riccardo; Abu-Hanna, Ameen

    2009-01-01

    Summary This paper is based on a panel discussion held at the Artificial Intelligence in Medicine Europe (AIME) conference in Amsterdam, The Netherlands, in July 2007. It had been more than 15 years since Edward Shortliffe gave a talk at AIME in which he characterized artificial intelligence (AI) in medicine as being in its “adolescence” (Shortliffe EH. The adolescence of AI in medicine: Will the field come of age in the ‘90s? Artificial Intelligence in Medicine 1993; 5:93–106). In this article, the discussants reflect on medical AI research during the subsequent years and attempt to characterize the maturity and influence that has been achieved to date. Participants focus on their personal areas of expertise, ranging from clinical decision making, reasoning under uncertainty, and knowledge representation to systems integration, translational bioinformatics, and cognitive issues in both the modeling of expertise and the creation of acceptable systems. PMID:18790621

  12. In-plant natural versus artificial aging study

    International Nuclear Information System (INIS)

    Shaw, M.

    1989-01-01

    A few years ago, cable specimens and small electrical components were placed in the reactor buildings of several operating nuclear plants in the United States. Temperature and radiation at the specimen locations are being monitored during the life of the plants. Measured physical properties of materials removed periodically during planned outages over the next 10 to 30 years will be compared with properties of artificially aged materials in identical specimens to assess artificial aging practice. This will also lead to improved lifetime predictions for cables and equipment. The study is being performed by the University of Connecticut's Institute for Materials Science in collaboration with U. S. utilities under the sponsorship of the Electric Power Research Institute (EPRI). Cofunding is being provided by Northeast Utilities and Detroit Edison. This paper gives the status of the study, along with some preliminary results

  13. Science in the age of accelerators

    International Nuclear Information System (INIS)

    Perl, M.L.

    1989-01-01

    Accelerators have brought the particle physicists to work and live in three worlds: the private world of science, the public world of science, and the world of large accelerators. The private world is the apparatus, the data, the theories, the colleagues, the journals, the meetings, and above all the understanding of elementary particles. The public world of science is how society sees scientists and how scientist want to be seen in newspapers and on TV, how scientist interact with governments, and most important how governments support science. 7 references, 20 figures

  14. Non-Destructive Failure Detection and Visualization of Artificially and Naturally Aged PV Modules

    Directory of Open Access Journals (Sweden)

    Gabriele C. Eder

    2018-04-01

    Full Text Available Several series of six-cell photovoltaic test-modules—intact and with deliberately generated failures (micro-cracks, cell cracks, glass breakage and connection defects—were artificially and naturally aged. They were exposed to various stress conditions (temperature, humidity and irradiation in different climate chambers in order to identify (i the stress-induced effects; (ii the potential propagation of the failures and (iii their influence on the performance. For comparison, one set of test-modules was also aged in an outdoor test site. All photovoltaic (PV modules were thoroughly electrically characterized by electroluminescence and performance measurements before and after the accelerated ageing and the outdoor test. In addition, the formation of fluorescence effects in the encapsulation of the test modules in the course of the accelerated ageing tests was followed over time using UV-fluorescence imaging measurements. It was found that the performance of PV test modules with mechanical module failures was rather unaffected upon storage under various stress conditions. However, numerous micro-cracks led to a higher rate of degradation. The polymeric encapsulate of the PV modules showed the build-up of distinctive fluorescence effects with increasing lifetime as the encapsulant material degraded under the influence of climatic stress factors (mainly irradiation by sunlight and elevated temperature by forming fluorophores. The induction period for the fluorescence effects of the polymeric encapsulant to be detectable was ~1 year of outdoor weathering (in middle Europe and 300 h of artificial irradiation (with 1000 W/m2 artificial sunlight 300–2500 nm. In the presence of irradiation, oxygen—which permeated into the module through the polymeric backsheet—bleached the fluorescence of the encapsulant top layer between the cells, above cell cracks and micro-cracks. Thus, UV-F imaging is a perfect tool for on-site detection of module failures

  15. Accelerated DNA Methylation Age: Associations with PTSD and Neural Integrity

    Science.gov (United States)

    Wolf, Erika J.; Logue, Mark W.; Hayes, Jasmeet P.; Sadeh, Naomi; Schichman, Steven A.; Stone, Annjanette; Salat, David H.; Milberg, William; McGlinchey, Regina; Miller, Mark W.

    2015-01-01

    Background Accumulating evidence suggests that post traumatic stress disorder (PTSD) may accelerate cellular aging and lead to premature morbidity and neurocognitive decline. Methods This study evaluated associations between PTSD and DNA methylation (DNAm) age using recently developed algorithms of cellular age by Horvath (2013) and Hannum et al. (2013). These estimates reflect accelerated aging when they exceed chronological age. We also examined if accelerated cellular age manifested in degraded neural integrity, indexed via diffusion tensor imaging. Results Among 281 male and female veterans of the conflicts in Iraq and Afghanistan, DNAm age was strongly related to chronological age (rs ~.88). Lifetime PTSD severity was associated with Hannum DNAm age estimates residualized for chronological age (β = .13, p= .032). Advanced DNAm age was associated with reduced integrity in the genu of the corpus callosum (β = −.17, p= .009) and indirectly linked to poorer working memory performance via this region (indirect β = − .05, p= .029). Horvath DNAm age estimates were not associated with PTSD or neural integrity. Conclusions Results provide novel support for PTSD-related accelerated aging in DNAm and extend the evidence base of known DNAm age correlates to the domains of neural integrity and cognition. PMID:26447678

  16. Pathology of Mouse Models of Accelerated Aging

    NARCIS (Netherlands)

    Harkema, L.; Youssef, S. A.; de Bruin, A.

    Progeroid mouse models display phenotypes in multiple organ systems that suggest premature aging and resemble features of natural aging of both mice and humans. The prospect of a significant increase in the global elderly population within the next decades has led to the emergence of geroscience,

  17. Pathology of Mouse Models of Accelerated Aging

    NARCIS (Netherlands)

    Harkema, L; Youssef, S A; de Bruin, A

    2016-01-01

    Progeroid mouse models display phenotypes in multiple organ systems that suggest premature aging and resemble features of natural aging of both mice and humans. The prospect of a significant increase in the global elderly population within the next decades has led to the emergence of "geroscience,"

  18. Method for accelerated aging under combined environmental stress conditions

    International Nuclear Information System (INIS)

    Gillen, K.T.

    1979-01-01

    An accelerated aging method which can be used to simulate aging in combined stress environment situations is described. It is shown how the assumptions of the method can be tested experimentally. Aging data for a chloroprene cable jacketing material in single and combined radiation and temperature environments are analyzed and it is shown that these data offer evidence for the validity of the method

  19. Mechanical properties of silorane-based and methacrylate-based composite resins after artificial aging.

    Science.gov (United States)

    de Castro, Denise Tornavoi; Lepri, César Penazzo; Valente, Mariana Lima da Costa; dos Reis, Andréa Cândido

    2016-01-01

    The aim of this study was to compare the compressive strength of a silorane-based composite resin (Filtek P90) to that of conventional composite resins (Charisma, Filtek Z250, Fill Magic, and NT Premium) before and after accelerated artificial aging (AAA). For each composite resin, 16 cylindrical specimens were prepared and divided into 2 groups. One group underwent analysis of compressive strength in a universal testing machine 24 hours after preparation, and the other was subjected first to 192 hours of AAA and then the compressive strength test. Data were analyzed by analysis of variance, followed by the Tukey HSD post hoc test (α = 0.05). Some statistically significant differences in compressive strength were found among the commercial brands (P aging. Comparison of each material before and after AAA revealed that the aging process did not influence the compressive strength of the tested resins (P = 0.785).

  20. Problems associated with accelerated thermal aging of electrical equipment

    International Nuclear Information System (INIS)

    Isgro, J.R.

    1984-01-01

    This paper discusses the potential problems that may be experienced when accounting for aging mechanisms in organic polymers when utilizing accelerated thermal aging techniques for electrical equipment qualification. Included are discussions of actual experiences and problems encountered in the qualification of electrical and electronic equipment for a complete nuclear power plant. The wide variety of approaches to thermal accelerated aging by various manufacturers of diverse equipment types provides depth to the discussion. A description of how to account for aging mechanisms is also presented

  1. Accelerated Aging with Electrical Overstress and Prognostics for Power MOSFETs

    Science.gov (United States)

    Saha, Sankalita; Celaya, Jose Ramon; Vashchenko, Vladislav; Mahiuddin, Shompa; Goebel, Kai F.

    2011-01-01

    Power electronics play an increasingly important role in energy applications as part of their power converter circuits. Understanding the behavior of these devices, especially their failure modes as they age with nominal usage or sudden fault development is critical in ensuring efficiency. In this paper, a prognostics based health management of power MOSFETs undergoing accelerated aging through electrical overstress at the gate area is presented. Details of the accelerated aging methodology, modeling of the degradation process of the device and prognostics algorithm for prediction of the future state of health of the device are presented. Experiments with multiple devices demonstrate the performance of the model and the prognostics algorithm as well as the scope of application. Index Terms Power MOSFET, accelerated aging, prognostics

  2. Translucency of Zirconia Ceramics before and after Artificial Aging.

    Science.gov (United States)

    Walczak, Katarzyna; Meißner, Heike; Range, Ursula; Sakkas, Andreas; Boening, Klaus; Wieckiewicz, Mieszko; Konstantinidis, Ioannis

    2018-03-11

    The aging of zirconia ceramics (Y-TZP) is associated with tetragonal to monoclinic phase transformation. This change in microstructure may affect the optical properties of the ceramic. This study examines the effect of aging on the translucency of different zirconia materials. 120 disc-shaped specimens were fabricated from four zirconia materials: Cercon ht white, BruxZir Solid Zirconia, Zenostar T0, Lava Plus (n = 30 per group). Accelerated aging was performed in a steam autoclave (134°C, 0.2 MPa, 5 hours). CIELab coordinates (L*, a*, b*) and luminous reflectance (Y) were measured with a spectrophotometer before and after aging. Contrast ratio (CR) and translucency parameter (TP) were calculated from the L*, a*, b*, and Y tristimulus values. The general linear model (Bonferroni adjusted) was used to compare both parameters before and after aging, as well as between the different zirconia materials (p ≤ 0.05). CR and TP differed significantly before and after aging in all groups tested. Before aging, Zenostar T showed the highest and Lava Plus showed the lowest translucency. After aging, Cercon ht and Zenostar T showed the highest and BruxZir and Lava Plus the lowest translucency. Aging reduced the translucency in all specimens tested. Furthermore, translucency differed between the zirconia brands tested. Nevertheless, the differences were below the detectability threshold of the human eye. The aging process can influence the translucency and thus the esthetic outcome of zirconia restorations; however, the changes in translucency were minimal and probably undetectable by the human eye. © 2018 by the American College of Prosthodontists.

  3. An artificial neural network model of energy expenditure using nonintegrated acceleration signals.

    Science.gov (United States)

    Rothney, Megan P; Neumann, Megan; Béziat, Ashley; Chen, Kong Y

    2007-10-01

    Accelerometers are a promising tool for characterizing physical activity patterns in free living. The major limitation in their widespread use to date has been a lack of precision in estimating energy expenditure (EE), which may be attributed to the oversimplified time-integrated acceleration signals and subsequent use of linear regression models for EE estimation. In this study, we collected biaxial raw (32 Hz) acceleration signals at the hip to develop a relationship between acceleration and minute-to-minute EE in 102 healthy adults using EE data collected for nearly 24 h in a room calorimeter as the reference standard. From each 1 min of acceleration data, we extracted 10 signal characteristics (features) that we felt had the potential to characterize EE intensity. Using these data, we developed a feed-forward/back-propagation artificial neural network (ANN) model with one hidden layer (12 x 20 x 1 nodes). Results of the ANN were compared with estimations using the ActiGraph monitor, a uniaxial accelerometer, and the IDEEA monitor, an array of five accelerometers. After training and validation (leave-one-subject out) were completed, the ANN showed significantly reduced mean absolute errors (0.29 +/- 0.10 kcal/min), mean squared errors (0.23 +/- 0.14 kcal(2)/min(2)), and difference in total EE (21 +/- 115 kcal/day), compared with both the IDEEA (P types under free-living conditions.

  4. Natural versus artificial aging of nuclear power plant components

    International Nuclear Information System (INIS)

    Shaw, M.T.

    1992-01-01

    This program seeks to understand the aging of polymeric materials, in cables and other components in nuclear reactor containment, by comparing aging processes for a variety of materials under natural conditions with those under the accelerated laboratory conditions used in qualification. The first five-year phase has been completed in what is planned as a long-term study of up to 40 years. Data from the program can be used as a basis of forecasting more realistic lifetimes in reactor service. The program is of critical importance for utilities both for the safe operation of plants and for minimizing the cost of periodic replacements upon expiration of originally predicted qualified life. The first five-year period has involved the selection and acquisition of test specimens, their preparation for placement in the containment, the selection of plants and locations for the specimens, the establishment of methods for monitoring radiation and temperature levels at each site, development of plans for scheduled removals, test method development, and testing of the specimens by physical and mechanical methods. Specimens have been subjected to short-term accelerated aging, as well as to reactor containment aging for up to five years. They consist of many types of polymers in products of several different manufacturers. Environmental conditions cover a wide range of temperature and radiation levels at 17 locations in 9 reactors of participating utilities. Initial results, which include tests of special cases subject to 8 years of reactor aging at Northeast Utilities, indicate several instances of changes having statistical significance in density or tensile properties due to containment service, but none of these changes are large enough to be of any concern. 12 refs., 19 figs., 21 tabs

  5. Effect of artificial aging on the roughness and microhardness of sealed composites.

    Science.gov (United States)

    Catelan, Anderson; Briso, André L F; Sundfeld, Renato H; Dos Santos, Paulo H

    2010-10-01

      The application of surface sealant could improve the surface quality and success of composite restorations; however, it is important to assess the behavior of this material when subjected to aging procedures.   To evaluate the effect of artificial aging on the surface roughness and microhardness of sealed microhybrids and nanofilled composites.   One hundred disc-shaped specimens were made for each composite. After 24 hours, all samples were polished and surface sealant was applied to 50 specimens of each composite. Surface roughness (Ra) was determined with a profilometer and Knoop microhardness was assessed with a 50-g load for 15 seconds. Ten specimens of each group were aged during 252 hours in a UV-accelerated aging chamber or immersed for 28 days in cola soft drink, orange juice, red wine staining solutions, or distilled water. Data were analyzed by two-way analysis of variance and Fischer's test (α=0.05).   Artificial aging decreased microhardness values for all materials, with the exceptions of Vit-l-escence (Ultradent Products Inc., South Jordan UT, USA) and Supreme XT (3M ESPE, St. Paul, MN, USA) sealed composites; surface roughness values were not altered. Water storage had less effect on microhardness, compared with the other aging processes. The sealed materials presented lower roughness and microhardness values, when compared with unsealed composites.   Aging methods decreased the microhardness values of a number of composites, with the exception of some sealed composites, but did not alter the surface roughness of the materials. The long-term maintenance of the surface quality of materials is fundamental to improving the longevity of esthetic restorations. In this manner, the use of surface sealants could be an important step in the restorative procedure using resin-based materials. © 2010, COPYRIGHT THE AUTHORS. JOURNAL COMPILATION © 2010, WILEY PERIODICALS, INC.

  6. Accelerated thermal and radiative ageing of hydrogenated NBR for DRC

    International Nuclear Information System (INIS)

    Mares, G.; Notingher, P.

    1996-01-01

    The accelerated thermal and gamma radiation ageing of HNBR carbon black-T80 has been studied by measuring the residual deformation under constant deflection -- DRC, in air, using a relevant equation for the relaxation phenomena. The residual deformation under constant deflection during the process of accelerated ageing is increasing but the structure of polymer answers in the proper manner to the mechanical stress. The degradation equations were obtained, using Alfrey model for the relaxation polymer subject to compression and an Arrhenius dependence for the chemical reaction rate. The inverted relaxation time for the thermal degradation is depending on the chemical reaction rate and the dose rate of gamma radiation

  7. Accelerated aging as vigor test for sunn hemp seeds

    OpenAIRE

    Silva, Clíssia Barboza da; Barbosa, Rafael Marani; Vieira, Roberval Daiton

    2016-01-01

    ABSTRACT: This study aimed to determine the most appropriate method to assess the sunn hemp ( Crotalaria juncea L.) seed vigor in the accelerated aging test. Five seed lots from harvest 2007/2008 were evaluated for germination, vigor and seedling emergence in the field. Accelerated aging test was performed at 41°C during 48, 72 and 96 hours, with and without sodium chloride saturated solution. Then, the promising procedure was also performed for 2008/2009 and 2009/2010 harvests. In the tradit...

  8. Accelerated aging as vigor test for sunn hemp seeds

    OpenAIRE

    Silva,Clíssia Barboza da; Barbosa,Rafael Marani; Vieira,Roberval Daiton

    2017-01-01

    ABSTRACT: This study aimed to determine the most appropriate method to assess the sunn hemp ( Crotalaria juncea L.) seed vigor in the accelerated aging test. Five seed lots from harvest 2007/2008 were evaluated for germination, vigor and seedling emergence in the field. Accelerated aging test was performed at 41°C during 48, 72 and 96 hours, with and without sodium chloride saturated solution. Then, the promising procedure was also performed for 2008/2009 and 2009/2010 harvests. In the tradit...

  9. Accelerator mass analyses of meteorites - carbon-14 terrestrial ages

    International Nuclear Information System (INIS)

    Miura, Y.; Rucklidge, J.; Beukens, R.; Fireman, E.

    1988-01-01

    Carbon-14 terrestrial ages of ten Antarctic meteorites have been measured by the IsoTrace accelerator mass spectrometry (AMS). The 14 C terrestrial age of 1 gram sample was determined from 14 C concentrations collected at melt and re-melt temperatures, compared with the 14 C concentration of the known Bruderheim chondrite. Yamato-790448 (LL3) chondrite was found to be the oldest terrestrial age of 3x10 4 years in the nine Yamato chondrites, whereas Yamato-791630 (L4) chondrite is considered to be the youngest chondrites less than thousand years. Allan Hills chondrite of ALH-77231 (L6) shows older terrestrial age than the nine Yamato chondrites. New accelerator data of the terrestrial age show higher accuracy with smaller sample than the previous counting method. (author)

  10. DeepX: Deep Learning Accelerator for Restricted Boltzmann Machine Artificial Neural Networks.

    Science.gov (United States)

    Kim, Lok-Won

    2018-05-01

    Although there have been many decades of research and commercial presence on high performance general purpose processors, there are still many applications that require fully customized hardware architectures for further computational acceleration. Recently, deep learning has been successfully used to learn in a wide variety of applications, but their heavy computation demand has considerably limited their practical applications. This paper proposes a fully pipelined acceleration architecture to alleviate high computational demand of an artificial neural network (ANN) which is restricted Boltzmann machine (RBM) ANNs. The implemented RBM ANN accelerator (integrating network size, using 128 input cases per batch, and running at a 303-MHz clock frequency) integrated in a state-of-the art field-programmable gate array (FPGA) (Xilinx Virtex 7 XC7V-2000T) provides a computational performance of 301-billion connection-updates-per-second and about 193 times higher performance than a software solution running on general purpose processors. Most importantly, the architecture enables over 4 times (12 times in batch learning) higher performance compared with a previous work when both are implemented in an FPGA device (XC2VP70).

  11. Accelerated brain aging in schizophrenia : A longitudinal pattern recognition study

    NARCIS (Netherlands)

    Schnack, Hugo G.; Van Haren, Neeltje E M; Nieuwenhuis, Mireille; Pol, Hilleke E Hulshoff; Cahn, Wiepke; Kahn, René S.

    2016-01-01

    OBJECTIVE: Despite the multitude of longitudinal neuroimaging studies that have been published, a basic question on the progressive brain loss in schizophrenia remains unaddressed: Does it reflect accelerated aging of the brain, or is it caused by a fundamentally different process? The authors used

  12. Accelerated Brain Aging in Schizophrenia : A Longitudinal Pattern Recognition Study

    NARCIS (Netherlands)

    Schnack, Hugo G; van Haren, Neeltje E M; Nieuwenhuis, Mireille; Hulshoff Pol, Hilleke E; Cahn, Wiepke; Kahn, René S

    2016-01-01

    OBJECTIVE: Despite the multitude of longitudinal neuroimaging studies that have been published, a basic question on the progressive brain loss in schizophrenia remains unaddressed: Does it reflect accelerated aging of the brain, or is it caused by a fundamentally different process? The authors used

  13. Dysregulated physiological stress systems and accelerated cellular aging

    NARCIS (Netherlands)

    Révész, D.; Verhoeven, J.; Milaneschi, Y.; de Geus, E.J.C.; Wolkowitz, O.M.; Penninx, B.W.J.H.

    2014-01-01

    Exposure to chronic stressors is associated with accelerated biological aging as indicated by reduced leukocyte telomere length (LTL). This impact could be because of chronic overactivation of the body's physiological stress systems. This study examined the associations between LTL and the immune

  14. The coming of age of artificial intelligence in medicine

    NARCIS (Netherlands)

    Patel, Vimla L.; Shortliffe, Edward H.; Stefanelli, Mario; Szolovits, Peter; Berthold, Michael R.; Bellazzi, Riccardo; Abu-Hanna, Ameen

    2009-01-01

    This paper is based on a panel discussion held at the Artificial Intelligence in Medicine Europe (AIME) conference in Amsterdam, The Netherlands, in July 2007. It had been more than 15 years since Edward Shortliffe gave a talk at AIME in which he characterized artificial intelligence (AI) in

  15. Lifetime sedentary living accelerates some aspects of secondary aging

    DEFF Research Database (Denmark)

    Booth, Frank W; Laye, Matthew J; Roberts, Michael D

    2011-01-01

    accelerates secondary aging (e.g., speeding the reduction in bone mineral density, maximal oxygen consumption, and skeletal muscle strength and power), but does not alter the primary aging of these systems. Third, a lifetime of physical activity to the age of ∼60-70 yr old totally prevents decrements in some...... role in the secondary aging of many essential physiological functions, and this aging can be prevented through a lifetime of physical activity.......Lifetime physical inactivity interacts with secondary aging (i.e., aging caused by diseases and environmental factors) in three patterns of response. First, lifetime physical inactivity confers no apparent effects on a given set of physiological functions. Second, lifetime physical inactivity...

  16. Accelerated Brain Aging in Schizophrenia: A Longitudinal Pattern Recognition Study.

    Science.gov (United States)

    Schnack, Hugo G; van Haren, Neeltje E M; Nieuwenhuis, Mireille; Hulshoff Pol, Hilleke E; Cahn, Wiepke; Kahn, René S

    2016-06-01

    Despite the multitude of longitudinal neuroimaging studies that have been published, a basic question on the progressive brain loss in schizophrenia remains unaddressed: Does it reflect accelerated aging of the brain, or is it caused by a fundamentally different process? The authors used support vector regression, a supervised machine learning technique, to address this question. In a longitudinal sample of 341 schizophrenia patients and 386 healthy subjects with one or more structural MRI scans (1,197 in total), machine learning algorithms were used to build models to predict the age of the brain and the presence of schizophrenia ("schizophrenia score"), based on the gray matter density maps. Age at baseline ranged from 16 to 67 years, and follow-up scans were acquired between 1 and 13 years after the baseline scan. Differences between brain age and chronological age ("brain age gap") and between schizophrenia score and healthy reference score ("schizophrenia gap") were calculated. Accelerated brain aging was calculated from changes in brain age gap between two consecutive measurements. The age prediction model was validated in an independent sample. In schizophrenia patients, brain age was significantly greater than chronological age at baseline (+3.36 years) and progressively increased during follow-up (+1.24 years in addition to the baseline gap). The acceleration of brain aging was not constant: it decreased from 2.5 years/year just after illness onset to about the normal rate (1 year/year) approximately 5 years after illness onset. The schizophrenia gap also increased during follow-up, but more pronounced variability in brain abnormalities at follow-up rendered this increase nonsignificant. The progressive brain loss in schizophrenia appears to reflect two different processes: one relatively homogeneous, reflecting accelerated aging of the brain and related to various measures of outcome, and a more variable one, possibly reflecting individual variation and

  17. An activated energy approach for accelerated testing of the deformation of UHMWPE in artificial joints.

    Science.gov (United States)

    Galetz, Mathias Christian; Glatzel, Uwe

    2010-05-01

    The deformation behavior of ultrahigh molecular polyethylene (UHMWPE) is studied in the temperature range of 23-80 degrees C. Samples are examined in quasi-static compression, tensile and creep tests to determine the accelerated deformation of UHMWPE at elevated temperatures. The deformation mechanisms under compression load can be described by one strain rate and temperature dependent Eyring process. The activation energy and volume of that process do not change between 23 degrees C and 50 degrees C. This suggests that the deformation mechanism under compression remains stable within this temperature range. Tribological tests are conducted to transfer this activated energy approach to the deformation behavior under loading typical for artificial knee joints. While this approach does not cover the wear mechanisms close to the surface, testing at higher temperatures is shown to have a significant potential to reduce the testing time for lifetime predictions in terms of the macroscopic creep and deformation behavior of artificial joints. Copyright 2010. Published by Elsevier Ltd.

  18. The application of artificial intelligent techniques to accelerator operations at McMaster University

    Science.gov (United States)

    Poehlman, W. F. S.; Garland, Wm. J.; Stark, J. W.

    1993-06-01

    In an era of downsizing and a limited pool of skilled accelerator personnel from which to draw replacements for an aging workforce, the impetus to integrate intelligent computer automation into the accelerator operator's repertoire is strong. However, successful deployment of an "Operator's Companion" is not trivial. Both graphical and human factors need to be recognized as critical areas that require extra care when formulating the Companion. They include interactive graphical user's interface that mimics, for the operator, familiar accelerator controls; knowledge of acquisition phases during development must acknowledge the expert's mental model of machine operation; and automated operations must be seen as improvements to the operator's environment rather than threats of ultimate replacement. Experiences with the PACES Accelerator Operator Companion developed at two sites over the past three years are related and graphical examples are given. The scale of the work involves multi-computer control of various start-up/shutdown and tuning procedures for Model FN and KN Van de Graaff accelerators. The response from licensing agencies has been encouraging.

  19. The application of artificial intelligent techniques to accelerator operations at McMaster University

    International Nuclear Information System (INIS)

    Poehlman, W.F.S.; Garland, W.J.; Stark, J.W.

    1993-01-01

    In an era of downsizing and a limited pool of skilled accelerator personnel from which to draw replacements for an aging workforce, the impetus to integrate intelligent computer automation into the accelerator operator's repertoire is strong. However, successful deployment of an 'Operator's Companion' is not trivial. Both graphical and human factors need to be recognized as critical areas that require extra care when formulating the Companion. They include interactive graphical user's interface that mimics, for the operator, familiar accelerator controls; knowledge of acquisition phases during development must acknowledge the expert's mental model of machine operation; and automated operations must be seen as improvements to the operator's environment rather than threats of ultimate replacement. Experiences with the PACES Accelerator Operator Companion developed at two sites over the past three years are related and graphical examples are given. The scale of the work involves multi-computer control of various start-up/shutdown and tuning procedures for Model FN and KN Van de Graaff accelerators. The response from licensing agencies has been encouraging. (orig.)

  20. Accelerated aging of AP/HTPB propellants and the influence of various environmental aging conditions

    NARCIS (Netherlands)

    Keizers, H.L.J.

    1995-01-01

    Preliminary resuits on accelerated aging of lab-scale produced AP/HTPB propellant and propellants from dissectioned rocket motors are discussed, including aging logic, storage conditions, test techniques and resuits on mechanical, ballistic and safety testing. The mam aging effect observed was

  1. Evaluation of aging and hydration in natural volcanic glass: magnetic property variations during artificial aging and hydration experiments

    Science.gov (United States)

    Bowles, J. A.; Patiman, A.

    2017-12-01

    The recorded geomagnetic field intensity is a function of magnetic mineralogy, grain size, and mineral concentration as well as material stability in nature and during laboratory experiments. Fresh, unhydrated, volcanic glasses are recognized as a nearly ideal natural material for use in paleointensity experiments because they contain the requisite single domain to pseudo-single-domain magnetic particles. Although alteration of magnetic mineralogy can be monitored during the experiments, it is unclear how mineralogy and hence magnetization might change with age as the metastable glass structure relaxes and/or the glass becomes hydrated. Bulk magnetic properties as a function of age show no clear trend, even over hundreds of millions of years. This may be due to the fact that even in fresh, unhydrated glass, there are small-scale differences in magnetic properties due to variation cooling rate or composition variations. Therefore, in order to better understand how magnetic mineralogy evolves with time and hydration, we conducted artificial aging and hydration experiments on fresh, unhydrated rhyolitic (South Deadman Creek, California, 650-yr) and basaltic (Axial Seamount, 2011) end-member glasses. Here, we present the results of artificial aging and hydration experiments. Elevated temperatures accelerate the glass relaxation process in a way that relaxation time decreases with increasing temperature. Aged samples are dry-annealed at 200, 300 and 400 °C for up to 240 days. A second set of samples are hydrated under pressure at 300°C and 450°C. In all cases, isothermal remanent magnetization (IRM) acquisition is monitored to assess changes in the coercivity spectrum and saturation IRM. Preliminary aging results show that in basaltic and rhyolitic glass there is one main peak coercivity at 150 mT and 35 mT, respectively. An increasing sIRM and decreasing peak coercivity trend is observed in basaltic glass whereas no trend is shown in the rhyolitic glass in both

  2. Accelerated age hardening by plastic deformation in Al-Cu with minor additions of Si and Ge

    International Nuclear Information System (INIS)

    Victoria Castro Riglos, M.; Taquire de la Cruz, M.; Tolley, Alfredo

    2011-01-01

    An extremely fast hardening response with no reduction in peak hardness was obtained in Al-Cu with minor additions of Si and Ge by 8% plastic deformation before artificial aging. The mechanism for the accelerated hardening was determined by detailed characterization with transmission electron microscopy. Plastic deformation was found to enhance the nucleation rate of Si-Ge precipitates, resulting in a higher volume density. Such precipitates catalyzed the formation of θ' precipitates that are responsible for hardening.

  3. DEVELOPMENT OF A LOW COST CAMERA FOR AGING ACCELERATED POLYMERS

    Directory of Open Access Journals (Sweden)

    Carlos Henrique Duarte Felisbino

    2018-03-01

    Full Text Available The objective of this paper is to describe the design, construction and testing of a low cost chamber for accelerated aging of polymers that meets a low and high ultraviolet radiation cycle on the test specimens in accordance with ASTM G154. The methodology was based on the survey of the standards related to the tests of accelerated aging of polymers and of the existing equipment, providing the subsidies for the development of the project, which was validated by the construction and evaluation of its performance. The camera control is performed by an Arduino-based electronic system and uses commercially available components that meet project specifications. The equipment met the requirements for both the specifications and the low cost and will integrate the laboratories of the University of Mogi das Cruzes (UMC, Villa-Lobos campus, to carry out tests on polymer materials.

  4. Parasite infection accelerates age polyethism in young honey bees

    DEFF Research Database (Denmark)

    Lecocq, Antoine; Jensen, Annette Bruun; Kryger, Per

    2016-01-01

    micro-colonies of honey bees and video analyses to track the effects of N. ceranae infection and exposure on a range of individual and social behaviours in young adult bees. We provide detailed data showing that N. ceranae infection significantly accelerated the age polyethism of young bees, causing......Honey bees (Apis mellifera) are important pollinators and their health is threatened worldwide by persistent exposure to a wide range of factors including pesticides, poor nutrition, and pathogens. Nosema ceranae is a ubiquitous microsporidian associated with high colony mortality. We used lab...... manipulation to increase colony infection. However, reduction in queen contacts could help bees limit the spread of infection. Such accelerated age polyethism may provide a form of behavioural immunity, particularly if it is elicited by a wide variety of pathogens....

  5. Aging accelerates memory extinction and impairs memory restoration in Drosophila.

    Science.gov (United States)

    Chen, Nannan; Guo, Aike; Li, Yan

    2015-05-15

    Age-related memory impairment (AMI) is a phenomenon observed from invertebrates to human. Memory extinction is proposed to be an active inhibitory modification of memory, however, whether extinction is affected in aging animals remains to be elucidated. Employing a modified paradigm for studying memory extinction in fruit flies, we found that only the stable, but not the labile memory component was suppressed by extinction, thus effectively resulting in higher memory loss in aging flies. Strikingly, young flies were able to fully restore the stable memory component 3 h post extinction, while aging flies failed to do so. In conclusion, our findings reveal that both accelerated extinction and impaired restoration contribute to memory impairment in aging animals. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Mechanisms controlling the artificial aging of Al-Mg-Si Alloys

    International Nuclear Information System (INIS)

    Pogatscher, S.; Antrekowitsch, H.; Leitner, H.; Ebner, T.; Uggowitzer, P.J.

    2011-01-01

    Highlights: → Artificial aging of Al-Mg-Si alloys in the range of 150 and 250 deg. C. → We study precipitation kinetics caused by various thermal histories. → Natural pre-aging affects kinetics at low artificial aging temperatures. → Natural pre-aging promotes kinetics at high artificial aging temperatures. → A vacancy-prison mechanism explains the effect of natural pre-aging. - Abstract: In this study the artificial aging behavior of the Al-Mg-Si alloy AA 6061 was investigated in the temperature range 150-250 deg. C using atom probe tomography, hardness and resistivity measurements for various thermal histories. It was found that the precipitation kinetics and age-hardening response of artificial aging at temperatures below 210 deg. C are lowered by prior natural aging but enhanced above this temperature. An analysis of hardness data was used to evaluate the temperature dependence of precipitation kinetics and dissolution processes. Supported by theoretical considerations, it is assumed that artificial aging of Al-Mg-Si alloys is controlled via the concentration of mobile vacancies. The 'vacancy-prison mechanism' proposed determines the mobile vacancy concentration in the case of natural pre-aging by temperature-dependent dissolution of co-clusters and solute-vacancy interactions.

  7. Comparison study on mechanical properties single step and three step artificial aging on duralium

    Science.gov (United States)

    Tsamroh, Dewi Izzatus; Puspitasari, Poppy; Andoko, Sasongko, M. Ilman N.; Yazirin, Cepi

    2017-09-01

    Duralium is kind of non-ferro alloy that used widely in industrial. That caused its properties such as mild, high ductility, and resistance from corrosion. This study aimed to know mechanical properties of duralium on single step and three step articial aging process. Mechanical properties that discussed in this study focused on toughness value, tensile strength, and microstructure of duralium. Toughness value of single step artificial aging was 0.082 joule/mm2, and toughness value of three step artificial aging was 0,0721 joule/mm2. Duralium tensile strength of single step artificial aging was 32.36 kgf/mm^2, and duralium tensile strength of three step artificial aging was 32,70 kgf/mm^2. Based on microstructure photo of duralium of single step artificial aging showed that precipitate (θ) was not spreading evenly indicated by black spot which increasing the toughness of material. While microstructure photo of duralium that treated by three step artificial aging showed that it had more precipitate (θ) spread evenly compared with duralium that treated by single step artificial aging.

  8. Accelerated optical polymer aging studies for LED luminaire applications

    Science.gov (United States)

    Estupiñán, Edgar; Wendling, Peter; Kostrun, Marijan; Garner, Richard

    2013-09-01

    There is a need in the lighting industry to design and implement accelerated aging methods that accurately simulate the aging process of LED luminaire components. In response to this need, we have built a flexible and reliable system to study the aging characteristics of optical polymer materials, and we have employed it to study a commercially available LED luminaire diffuser made of PMMA. The experimental system consists of a "Blue LED Emitter" and a working surface. Both the temperatures of the samples and the optical powers of the LEDs are appropriately characterized in the system. Several accelerated aging experiments are carried out at different temperatures and optical powers over a 90 hour period and the measured transmission values are used as inputs to a degradation model derived using plausibility arguments. This model seems capable of predicting the behavior of the material as a function of time, temperature and optical power. The model satisfactorily predicts the measured transmission values of diffusers aged in luminaires at two different times and thus can be used to make application recommendations for this material. Specifically, at 35000 hours (the manufacturer's stated life of the luminaire) and at the typical operational temperature of the diffuser, the model predicts a transmission loss of only a few percent over the original transmission of the material at 450 nm, which renders this material suitable for this application.

  9. Electrochemical migration technique to accelerate ageing of cementitious materials

    Directory of Open Access Journals (Sweden)

    Abbas Z.

    2013-07-01

    Full Text Available Durability assessment of concrete structures for constructions in nuclear waste repositories requires long term service life predictions. As deposition of low and intermediate level radioactive waste (LILW takes up to 100 000 years, it is necessary to analyze the service life of cementitious materials in this time perspective. Using acceleration methods producing aged specimens would decrease the need of extrapolating short term data sets. Laboratory methods are therefore, needed for accelerating the ageing process without making any influencing distortion in the properties of the materials. This paper presents an electro-chemical migration method to increase the rate of calcium leaching from cementitious specimens. This method is developed based on the fact that major long term deterioration process of hardened cement paste in concrete structures for deposition of LILW is due to slow diffusion of calcium ions. In this method the cementitious specimen is placed in an electrochemical cell as a porous path way through which ions can migrate at a rate far higher than diffusion process. The electrical field is applied to the cell in a way to accelerate the ion migration without making destructions in the specimen’s micro and macroscopic properties. The anolyte and catholyte solutions are designed favoring dissolution of calcium hydroxide and compensating for the leached calcium ions with another ion like lithium.

  10. Electrochemical migration technique to accelerate ageing of cementitious materials

    Science.gov (United States)

    Babaahmadi, A.; Tang, L.; Abbas, Z.

    2013-07-01

    Durability assessment of concrete structures for constructions in nuclear waste repositories requires long term service life predictions. As deposition of low and intermediate level radioactive waste (LILW) takes up to 100 000 years, it is necessary to analyze the service life of cementitious materials in this time perspective. Using acceleration methods producing aged specimens would decrease the need of extrapolating short term data sets. Laboratory methods are therefore, needed for accelerating the ageing process without making any influencing distortion in the properties of the materials. This paper presents an electro-chemical migration method to increase the rate of calcium leaching from cementitious specimens. This method is developed based on the fact that major long term deterioration process of hardened cement paste in concrete structures for deposition of LILW is due to slow diffusion of calcium ions. In this method the cementitious specimen is placed in an electrochemical cell as a porous path way through which ions can migrate at a rate far higher than diffusion process. The electrical field is applied to the cell in a way to accelerate the ion migration without making destructions in the specimen's micro and macroscopic properties. The anolyte and catholyte solutions are designed favoring dissolution of calcium hydroxide and compensating for the leached calcium ions with another ion like lithium.

  11. BrainAGE score indicates accelerated brain aging in schizophrenia, but not bipolar disorder.

    Science.gov (United States)

    Nenadić, Igor; Dietzek, Maren; Langbein, Kerstin; Sauer, Heinrich; Gaser, Christian

    2017-08-30

    BrainAGE (brain age gap estimation) is a novel morphometric parameter providing a univariate score derived from multivariate voxel-wise analyses. It uses a machine learning approach and can be used to analyse deviation from physiological developmental or aging-related trajectories. Using structural MRI data and BrainAGE quantification of acceleration or deceleration of in individual aging, we analysed data from 45 schizophrenia patients, 22 bipolar I disorder patients (mostly with previous psychotic symptoms / episodes), and 70 healthy controls. We found significantly higher BrainAGE scores in schizophrenia, but not bipolar disorder patients. Our findings indicate significantly accelerated brain structural aging in schizophrenia. This suggests, that despite the conceptualisation of schizophrenia as a neurodevelopmental disorder, there might be an additional progressive pathogenic component. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

  12. Accelerated aging tests of liners for uranium mill tailings disposal

    International Nuclear Information System (INIS)

    Barnes, S.M.; Buelt, J.L.; Hale, V.Q.

    1981-11-01

    This document describes the results of accelerated aging tests to determine the long-term effectiveness of selected impoundment liner materials in a uranium mill tailings environment. The study was sponsored by the US Department of Energy under the Uranium Mill Tailings Remedial Action Project. The study was designed to evaluate the need for, and the performance of, several candidate liners for isolating mill tailings leachate in conformance with proposed Environmental Protection Agency and Nuclear Regulatory Commission requirements. The liners were subjected to conditions known to accelerate the degradation mechanisms of the various liners. Also, a test environment was maintained that modeled the expected conditions at a mill tailings impoundment, including ground subsidence and the weight loading of tailings on the liners. A comparison of installation costs was also performed for the candidate liners. The laboratory testing and cost information prompted the selection of a catalytic airblown asphalt membrane and a sodium bentonite-amended soil for fiscal year 1981 field testing

  13. TANNED LEATHERS PROPERTIES MODIFICATION AS A RESULT OF ARTIFICIAL AGEING

    Directory of Open Access Journals (Sweden)

    ROŞU Dan

    2017-05-01

    Full Text Available Leather is a high tech material with different application fields, such as automotive, manufacturing of leatherwear articles or clothing and footwear. Leather is a biomaterial obtained by processing animal skins. Unfortunately, raw animal hides are practically inutilizable, due to their microbiological instability and are affected by rotting. Microbiological stability is achieved by tanning, when the protein is crosslinked, followed by drying. After crosslinking and drying, the new material shows the required properties of sustainability, availability and an esthetically pleasing aspect to the touch, making it available across its entire range of applications. From a structural point of view the animal skins are constituted of collagen, which is a fibrilar protein with a high degree of supramolecular organization in triple helix form that endows softness, elasticity and mechanical strength. High quality standards and lack of toxicity are required in all cases. Leather colour changes during exposure to light radiations are considered a consequence of the presence of some products with weak photochemical resistance during fabrication. The study aims to compare changes in properties of leathers obtained using mineral tanning agents such as Cr III salts and those obtained with the more environment-friendly technology using acid hydrolysis. Accelerated aging studies were conducted on tanned leathers by exposing the samples to UV radiation with different irradiation doses and two wavelengths (254 and 365 nm under controlled humidity and temperature conditions. Structural changes caused by irradiation were studied by FTIR. Colour changes on the sample surfaces were assessed during irradiation with the CIEL a*b* system. The colour parameters variation (L*, a*, b* and colour differences have been discussed in correlation with structural changes, tanning method and irradiation conditions.

  14. Moisture Sorption in Artificially aged wood-plastic composites

    Science.gov (United States)

    B. Kristoffer Segerholm; Rebecca E. Ibach; Magnus E.P. Wålinder

    2012-01-01

    Moisture sorption in wood-plastic composites (WPCs) affects their durability and dimensional stability. In certain outdoor exposures, the moisture properties of WPCs are altered due to e.g. cracks induced by swelling and shrinkage of the components, as well as UV degradation or biological attack. The aim of this work was to study the effect of different artificial...

  15. Color stability of sealed composite resin restorative materials after ultraviolet artificial aging and immersion in staining solutions.

    Science.gov (United States)

    Catelan, Anderson; Briso, André Luiz Fraga; Sundfeld, Renato Hermann; Goiato, Marcelo Coelho; dos Santos, Paulo Henrique

    2011-04-01

    The color alteration of resin-based materials is one of the most common reasons to replace esthetic dental restorations. This study assessed the influence of surface sealant (Biscover) on the color stability of nanofilled (Supreme XT) and microhybrid (Vit-l-escence and Opallis) composite resins after artificial aging. One hundred disc-shaped (6 × 1.5 mm) specimens were made for each composite resin. After 24 hours, all specimens were polished and sealant was applied to 50 specimens of each material. Baseline color was measured according to the CIE L*a*b* system using a reflection spectrophotometer. Ten specimens of each group were aged for 252 h in an ultraviolet (UV)-accelerated aging chamber or immersed for 4 weeks in cola soft drink, orange juice, red wine staining solutions or distilled water as control. Color difference (ΔE) after aging was calculated based on the color coordinates before (baseline) and after aging/staining treatment. Data were analyzed with 2-way ANOVA and Fisher's test (α=.05). The results showed significant changes in color after artificial aging in all the groups (Paging, and the cola soft drink. The lowest values of ΔE were found for specimens stored in distilled water. All composite resins showed some color alteration after the aging methods. The surface sealant did not alter the color stability of the tested materials. Copyright © 2011 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  16. Accelerated Aging Test for Plastic Scintillator Gamma Ray Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Kouzes, Richard T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2017-05-12

    Polyvinyl toluene (PVT) and polystyrene (PS), collectively referred to as “plastic scintillator,” are synthetic polymer materials used to detect gamma radiation, and are commonly used in instrumentation. Recent studies have revealed that plastic scintillator undergoes an environmentally related material degradation that adversely affects performance under certain conditions and histories. A significant decrease in gamma ray sensitivity has been seen in some detectors in systems as they age. The degradation of sensitivity of plastic scintillator over time is due to a variety of factors, and the term “aging” is used to encompass all factors. Some plastic scintillator samples show no aging effects (no significant change in sensitivity over more than 10 years), while others show severe aging (significant change in sensitivity in less than 5 years). Aging effects arise from weather (variations in heat and humidity), chemical exposure, mechanical stress, light exposure, and loss of volatile components. The damage produced by these various causes can be cumulative, causing observable damage to increase over time. Damage may be reversible up to some point, but becomes permanent under some conditions. It has been demonstrated that exposure of plastic scintillator in an environmental chamber to 30 days of high temperature and humidity (90% relative humidity and 55°C) followed by a single cycle to cold temperature (-30°C) will produce severe fogging in all PVT samples. This thermal cycle will be referred to as the “Accelerated Aging Test.” This document describes the procedure for performing this Accelerated Aging Test.

  17. Idh2 deficiency accelerates renal dysfunction in aged mice.

    Science.gov (United States)

    Lee, Su Jeong; Cha, Hanvit; Lee, Seoyoon; Kim, Hyunjin; Ku, Hyeong Jun; Kim, Sung Hwan; Park, Jung Hyun; Lee, Jin Hyup; Park, Kwon Moo; Park, Jeen-Woo

    2017-11-04

    The free radical or oxidative stress theory of aging postulates that senescence is due to an accumulation of cellular oxidative damage, caused largely by reactive oxygen species (ROS) that are produced as by-products of normal metabolic processes in mitochondria. The oxidative stress may arise as a result of either increased ROS production or decreased ability to detoxify ROS. The availability of the mitochondrial NADPH pool is critical for the maintenance of the mitochondrial antioxidant system. The major enzyme responsible for generating mitochondrial NADPH is mitochondrial NADP + -dependent isocitrate dehydrogenase (IDH2). Depletion of IDH2 in mice (idh2 -/- ) shortens life span and accelerates the degeneration of multiple age-sensitive traits, such as hair grayness, skin pathology, and eye pathology. Among the various internal organs tested in this study, IDH2 depletion-induced acceleration of senescence was uniquely observed in the kidney. Renal function and structure were greatly deteriorated in 24-month-old idh2 -/- mice compared with wild-type. In addition, disruption of redox status, which promotes oxidative damage and apoptosis, was more pronounced in idh2 -/- mice. These data support a significant role for increased oxidative stress as a result of compromised mitochondrial antioxidant defenses in modulating life span in mice, and thus support the oxidative stress theory of aging. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. MORPHOLOGICAL CHANGES IN THE HIPPOCAMPUS OF RATS IN ACCELERATED AGING

    Directory of Open Access Journals (Sweden)

    K. Yu. Maksimova

    2014-01-01

    Full Text Available The aim of this work was the analysis of structural changes with age in the hippocampus of senescenceaccelerated OXYS rats when signs of accelerated brain aging are missing (age 14 days, developments (age 5 months, and active progresses (age 15 months. The study was performed on 15 OXYS rats and 15 Wistar rats (as a control. After dislocation, brains were dissected, fixed with 10% formalin, embedded in paraffin, and serially cut in coronal sections (5μm thickness. These sections were stained with Cresyl violet and examined with a photomicroscope (Carl Zeiss Axiostar plus, Germany. The total number of hippocampal pyramidal cells in the CA1, CA3 and the dentate gyrus regions were estimated in 14-dayold, 5and 15-month-old OXYS and Wistar rats (n = 5 on the 5 slices of each brain sections. The number of neurons with chromatolysis, hyperchromatic with darkly stained cytoplasm and shrunken neurons were calculated as degenerative neurons. The pictures obtained with the program Carl Zeiss Axio Vision 8.0 with increasing 10  100, determined the average area bodies and nuclei of neurons (mkm2. The significant structural changes of neurons in the CA1, CA3 and dentate gyrus regions of the hippocampus in OXYS rats at 5 month of age are revealed by light microscopy. This results indicates the early develop neurodegeneration in OXYS rats. The most pronounced morphological changes occur in the CA1 region of the hippocampus of OXYS rats and irreversible. The degenerative changes of neurons in the hippocampus increases by the age of 15 months. Morphometric analysis of the average area of bodies and the nuclei of hippocampal neurons in CA1, CA3 and the dentate gyrus regions of OXYS and Wistar rats at 14 days of age showed no significant interline differences. At 5 months of age in the CA1 region of the hippocampus of OXYS rats was determined a significantly lower average body size and nuclei of pyramidal neurons compared with Wistar rats. With age, these

  19. Repair mortars based on lime. Accelerated aging tests

    Directory of Open Access Journals (Sweden)

    Martínez-Ramírez, S.

    1995-06-01

    Full Text Available The behaviour under different accelerated aging tests (freeze/thaw and crystallization cycles of a new lime mortar with biocide properties destinated to monumental repair has been studied. New mortars (which have the biocide impregnated in a clay called sepiolite have a similar behaviour to lime mortars used as a reference. After the aging tests, the biocide properties of the mortars have been tried.

    Se ha estudiado el comportamiento frente a distintos ensayos de envejecimiento acelerado (ciclos de hielo/deshielo y cristalización de sales de un nuevo mortero de cal con propiedades biocidas, destinado a la reparación monumental. Se ha comprobado que los nuevos morteros (que llevan incorporado el biocida impregnado en una arcilla denominada sepiolita tienen un comportamiento muy similar a los morteros de cal utilizados como referencia. Tras los ensayos de envejecimiento se ha visto que las propiedades biocidas de los morteros se mantienen.

  20. Acrylamide induces accelerated endothelial aging in a human cell model.

    Science.gov (United States)

    Sellier, Cyril; Boulanger, Eric; Maladry, François; Tessier, Frédéric J; Lorenzi, Rodrigo; Nevière, Rémi; Desreumaux, Pierre; Beuscart, Jean-Baptiste; Puisieux, François; Grossin, Nicolas

    2015-09-01

    Acrylamide (AAM) has been recently discovered in food as a Maillard reaction product. AAM and glycidamide (GA), its metabolite, have been described as probably carcinogenic to humans. It is widely established that senescence and carcinogenicity are closely related. In vitro, endothelial aging is characterized by replicative senescence in which primary cells in culture lose their ability to divide. Our objective was to assess the effects of AAM and GA on human endothelial cell senescence. Human umbilical vein endothelial cells (HUVECs) cultured in vitro were used as model. HUVECs were cultured over 3 months with AAM or GA (1, 10 or 100 μM) until growth arrest. To analyze senescence, β-galactosidase activity and telomere length of HUVECs were measured by cytometry and semi-quantitative PCR, respectively. At all tested concentrations, AAM or GA reduced cell population doubling compared to the control condition (p < 0.001). β-galactosidase activity in endothelial cells was increased when exposed to AAM (≥10 μM) or GA (≥1 μM) (p < 0.05). AAM (≥10 μM) or GA (100 μM) accelerated telomere shortening in HUVECs (p < 0.05). In conclusion, in vitro chronic exposure to AAM or GA at low concentrations induces accelerated senescence. This result suggests that an exposure to AAM might contribute to endothelial aging. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Parasite infection accelerates age polyethism in young honey bees

    Science.gov (United States)

    Lecocq, Antoine; Jensen, Annette Bruun; Kryger, Per; Nieh, James C.

    2016-01-01

    Honey bees (Apis mellifera) are important pollinators and their health is threatened worldwide by persistent exposure to a wide range of factors including pesticides, poor nutrition, and pathogens. Nosema ceranae is a ubiquitous microsporidian associated with high colony mortality. We used lab micro-colonies of honey bees and video analyses to track the effects of N. ceranae infection and exposure on a range of individual and social behaviours in young adult bees. We provide detailed data showing that N. ceranae infection significantly accelerated the age polyethism of young bees, causing them to exhibit behaviours typical of older bees. Bees with high N. ceranae spore counts had significantly increased walking rates and decreased attraction to queen mandibular pheromone. Infected bees also exhibited higher rates of trophallaxis (food exchange), potentially reflecting parasite manipulation to increase colony infection. However, reduction in queen contacts could help bees limit the spread of infection. Such accelerated age polyethism may provide a form of behavioural immunity, particularly if it is elicited by a wide variety of pathogens. PMID:26912310

  2. Parasite infection accelerates age polyethism in young honey bees.

    Science.gov (United States)

    Lecocq, Antoine; Jensen, Annette Bruun; Kryger, Per; Nieh, James C

    2016-02-25

    Honey bees (Apis mellifera) are important pollinators and their health is threatened worldwide by persistent exposure to a wide range of factors including pesticides, poor nutrition, and pathogens. Nosema ceranae is a ubiquitous microsporidian associated with high colony mortality. We used lab micro-colonies of honey bees and video analyses to track the effects of N. ceranae infection and exposure on a range of individual and social behaviours in young adult bees. We provide detailed data showing that N. ceranae infection significantly accelerated the age polyethism of young bees, causing them to exhibit behaviours typical of older bees. Bees with high N. ceranae spore counts had significantly increased walking rates and decreased attraction to queen mandibular pheromone. Infected bees also exhibited higher rates of trophallaxis (food exchange), potentially reflecting parasite manipulation to increase colony infection. However, reduction in queen contacts could help bees limit the spread of infection. Such accelerated age polyethism may provide a form of behavioural immunity, particularly if it is elicited by a wide variety of pathogens.

  3. Medical Education Must Move from the Information Age to the Age of Artificial Intelligence.

    Science.gov (United States)

    Wartman, Steven A; Combs, C Donald

    2017-11-01

    Changes to the medical profession require medical education reforms that will enable physicians to more effectively enter contemporary practice. Proposals for such reforms abound. Common themes include renewed emphasis on communication, teamwork, risk-management, and patient safety. These reforms are important but insufficient. They do not adequately address the most fundamental change--the practice of medicine is rapidly transitioning from the information age to the age of artificial intelligence. Employers need physicians who: work at the top of their license, have knowledge spanning the health professions and care continuum, effectively leverage data platforms, focus on analyzing outcomes and improving performance, and communicate the meaning of the probabilities generated by massive amounts of data to patients given their unique human complexities.Future medical practice will have four characteristics that must be addressed in medical education: care will be (1) provided in many locations; (2) provided by newly-constituted health care teams; and (3) based on a growing array of data from multiple sources and artificial intelligence applications; and (4) the interface between medicine and machines will need to be skillfully managed. Thus, medical education must make better use of the findings of cognitive psychology, pay more attention to the alignment of humans and machines in education, and increase the use of simulations. Medical education will need to evolve to include systematic curricular attention to the organization of professional effort among health professionals, the use of intelligence tools like machine learning and robots, and a relentless focus on improving performance and patient outcomes. [end of abstract].

  4. Natural and artificial aging response of semi-solid metal processed alloy A356

    CSIR Research Space (South Africa)

    Möller, H

    2008-09-01

    Full Text Available oC between 1 and 5 hours without any prior natural aging. A natural aging period as short as 1 hour results in a hardness peak (rather than a plateau) to be reached during artificial aging after 4 hours at 180oC...

  5. Desloratadine analysis: as a pharmaceutical preparation and after accelerating ageing

    Directory of Open Access Journals (Sweden)

    Bober Katarzyna

    2015-09-01

    Full Text Available Desloratadine is a biologically active compound that is not described in the Polish Pharmacopoeia IX, hence, its study is particular important. The aim of this work was to establish a procedure for desloratadine analysis by way of HPTLC in combination with densitometry, so as to be able to ascertain its presence and degree of presence within pharmaceutical preparations. In our work, a mixture of ethyl acetate, n-butanol, ammonia and methanol was used as the mobile phase. Moreover, HPTLC plates precoated with silica gel 60F254 were also employed. The proposed method was tested and subsequently validated. Spectrodensitometric analysis was then performed to determine the optimal wavelength for the quantitative determination (λ=276 nm, and following this, a quantitative analysis of desloratadine within certain pharmaceutical preparations was performed. Our research also took into consideration an analysis of the products of desloratadine decomposition that come about as a result of the accelerated aging of its solutions. The employed procedure for accelerating the aging of such desloratadine solutions consisted of heating these at 40℃ and then irradiating the solution surfaces with UV light. The changing color of these solutions after 2 hours of exposure served to indicate that degradation had occurred. Of note: as a result of irradiation with UV light, desloratadine content was seen to decrease with time, declining to almost zero after 30 hours. However, heating a solution of desloratadine alone did not induce a change in its content. Solutions of desloratadine that had previously undergone irradiation and heating were also analyzed to ascertain whether new substances were present. For this purpose, the GC-MS process was employed. As a result of this procedure, the spectrum of the solution after aging showed the presence of several new peaks that displayed retention several times larger and smaller than the normal desloratadine peak.

  6. Dysregulated physiological stress systems and accelerated cellular aging.

    Science.gov (United States)

    Révész, Dóra; Verhoeven, Josine E; Milaneschi, Yuri; de Geus, Eco J C N; Wolkowitz, Owen M; Penninx, Brenda W J H

    2014-06-01

    Exposure to chronic stressors is associated with accelerated biological aging as indicated by reduced leukocyte telomere length (LTL). This impact could be because of chronic overactivation of the body's physiological stress systems. This study examined the associations between LTL and the immune system, hypothalamic-pituitary-adrenal axis and autonomic nervous system. LTL was assessed in 2936 adults from the Netherlands Study of Depression and Anxiety. Inflammation markers (interleukin-6, c-reactive protein, tumor necrosis factor-alpha), hypothalamic-pituitary-adrenal-axis indicators (salivary cortisol awakening curve [area under the curve indicators, with respect to the ground and increase], evening levels, 0.5 mg dexamethasone cortisol suppression ratio), and autonomic nervous system measures (heart rate, respiratory sinus arrhythmia, pre-ejection period) were determined. Linear regression analyses were performed and adjusted for sociodemographic, lifestyle and clinical factors. Shorter LTL was significantly associated with higher c-reactive protein, interleukin-6, area under the curve with respect to increase, and heart rate. A cumulative index score was calculated based on the number of highest tertiles of these 4 stress markers. LTL demonstrated a significant gradient within subjects ranging from having zero (5528 base pairs) to having 4 elevated stress markers (5371 base pairs, p for trend = 0.002), corresponding to a difference of 10 years of accelerated biological aging. Contrary to the expectations, shorter LTL was also associated with longer pre-ejection period, indicating lower sympathetic tone. This large-scale study showed that inflammation, high awakening cortisol response, and increased heart rate are associated with shorter LTL, especially when they are dysregulated cumulatively. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Accelerated Aging System for Prognostics of Power Semiconductor Devices

    Science.gov (United States)

    Celaya, Jose R.; Vashchenko, Vladislav; Wysocki, Philip; Saha, Sankalita

    2010-01-01

    Prognostics is an engineering discipline that focuses on estimation of the health state of a component and the prediction of its remaining useful life (RUL) before failure. Health state estimation is based on actual conditions and it is fundamental for the prediction of RUL under anticipated future usage. Failure of electronic devices is of great concern as future aircraft will see an increase of electronics to drive and control safety-critical equipment throughout the aircraft. Therefore, development of prognostics solutions for electronics is of key importance. This paper presents an accelerated aging system for gate-controlled power transistors. This system allows for the understanding of the effects of failure mechanisms, and the identification of leading indicators of failure which are essential in the development of physics-based degradation models and RUL prediction. In particular, this system isolates electrical overstress from thermal overstress. Also, this system allows for a precise control of internal temperatures, enabling the exploration of intrinsic failure mechanisms not related to the device packaging. By controlling the temperature within safe operation levels of the device, accelerated aging is induced by electrical overstress only, avoiding the generation of thermal cycles. The temperature is controlled by active thermal-electric units. Several electrical and thermal signals are measured in-situ and recorded for further analysis in the identification of leading indicators of failures. This system, therefore, provides a unique capability in the exploration of different failure mechanisms and the identification of precursors of failure that can be used to provide a health management solution for electronic devices.

  8. The socio-organizational age of artificial intelligence in medicine.

    Science.gov (United States)

    Stefanelli, M

    2001-08-01

    The increasing pressure on Health Care Organizations (HCOs) to ensure efficiency and cost-effectiveness, balancing quality of care and cost containment, will drive them towards a more effective management of medical knowledge derived from research findings. The relation between science and health services has until recently been too casual. The primary job of medical research has been to understand the mechanisms of disease and produce new treatments, not to worry about the effectiveness of the new treatments or their implementation. As a result many new treatments have taken years to become part of routine practice, ineffective treatments have been widely used, and medicine has been opinion rather than evidence based. This results in suboptimal care for patients. Knowledge management technology may provide effective approaches in speeding up the diffusion of innovative medical procedures whose clinical effectiveness have been proved: the most interesting one is represented by computer-based utilization of evidence-based clinical guidelines. As researchers in Artificial Intelligence in Medicine (AIM), we are committed to foster the strategic transition from opinion to evidence-based decision making. Reviews of the effectiveness of various methods of guideline dissemination show that the most predictable impact is achieved when the guideline is made accessible through computer-based and patient specific reminders that are integrated into the clinician's workflow. However, the traditional single doctor-patient relationship is being replaced by one in which the patient is managed by a team of health care professionals, each specializing in one aspect of care. Such shared care depends critically on the ability to share patient-specific information and medical knowledge easily among them. Strategically there is a need to take a more clinical process view of health care delivery and to identify the appropriate organizational and information infrastructures to support

  9. Statistical analysis of data from accelerated ageing tests of PES UF membranes

    NARCIS (Netherlands)

    Zondervan, Edwin; Zwijnenburg, Arie; Roffel, Brian

    2007-01-01

    In this research, membrane life-time was evaluated by means of accelerated ageing experiments. A pressure pulse unit was used to perform the ageing experiments in an accelerated way. An experimental design has been set up and four ageing factors were varied at two levels. The four ageing factors

  10. Interdependent effect of chemical composition and thermal history on artificial aging of AA6061

    International Nuclear Information System (INIS)

    Pogatscher, S.; Antrekowitsch, H.; Uggowitzer, P.J.

    2012-01-01

    In this study, the interdependent effect of chemical composition and thermal history on artificial aging was investigated for the aluminum alloy AA6061. Based on thermodynamic calculations, including Al, Fe, Cr, Zn, Ti, Mg, Si and Cu, model alloys exhibiting a maximum variation of the reachable solute super-saturation of elements relevant for precipitation hardening within the compositional limits of AA6061 were produced. The artificial aging behavior of these alloys at 175 °C was studied by tensile testing for two thermal histories, including very short- and long-term room temperature storage after quenching. Precipitation during artificial aging was investigated by an analysis of yield strength data. As generally expected, precipitation kinetics was found to depend strongly on the solute super-saturation in the case of very short room temperature storage. For artificial aging after long-term room temperature storage the kinetics showed almost no dependence on the chemical composition. This seems to be an exception from simple precipitation kinetics and can be explained based on the complex role of quenched-in vacancies in artificial aging of AA6061.

  11. Volatile profile of Madeira wines submitted to traditional accelerated ageing.

    Science.gov (United States)

    Pereira, Vanda; Cacho, Juan; Marques, José C

    2014-11-01

    The evolution of monovarietal fortified Madeira wines forced-aged by traditional thermal processing (estufagem) were studied in terms of volatiles. SPE extracts were analysed by GC-MS before and after heating at 45 °C for 3 months (standard) and at 70 °C for 1 month (overheating). One hundred and ninety volatile compounds were identified, 53 of which were only encountered in baked wines. Most chemical families increased after standard heating, especially furans and esters, up to 61 and 3-fold, respectively. On the contrary, alcohols, acetates and fatty acids decreased after heating. Varietal aromas, such as Malvasia's monoterpenic alcohols were not detected after baking. The accelerated ageing favoured the development of some volatiles previously reported as typical aromas of finest Madeira wines, particularly phenylacetaldeyde, β-damascenone and 5-ethoxymethylfurfural. Additionally, ethyl butyrate, ethyl 2-methylbutyrate, ethyl caproate, ethyl isovalerate, guaiacol, 5-hydroxymethylfurfural and γ-decalactone were also found as potential contributors to the global aroma of baked wines. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Evaluation of Accelerated Ageing Tests for Metallic and Non-Metallic Graffiti Paints Applied to Stone

    Directory of Open Access Journals (Sweden)

    Patricia Sanmartín

    2017-10-01

    Full Text Available Graffiti are increasingly observed on urban and peri-urban buildings and their removal requires a huge financial outlay by local governments and agencies. Graffiti are not usually removed immediately, but rather over the passage of time, viz. months or even years. In this study, which forms part of a wider research project on graffiti removal, different methods (gravimetric analysis, examination of digital images, colour and infrared measurements were used to evaluate the performance of accelerated ageing tests (involving exposure to humidity, freeze-thawing cycles and NaCl and Na2SO4 salts for graffiti painted on stone. Silver (metallic and black (non-metallic graffiti spray paints were applied to two types of igneous rock (granite and rhyolitic ignimbrite and one sedimentary rock (fossiliferous limestone, i.e., biocalcarenite. The metallic and non-metallic graffiti spray paints acted differently on the stone surfaces, both chemically and physically. Older graffiti were found to be more vulnerable to weathering agents. The ageing test with NaCl and particularly Na2SO4, both applied to granite, proved the most severe on the paints, yielding more detrimental and faster artificial ageing of the type of material under study.

  13. An artificial intelligence tool for complex age-depth models

    Science.gov (United States)

    Bradley, E.; Anderson, K. A.; de Vesine, L. R.; Lai, V.; Thomas, M.; Nelson, T. H.; Weiss, I.; White, J. W. C.

    2017-12-01

    CSciBox is an integrated software system for age modeling of paleoenvironmental records. It incorporates an array of data-processing and visualization facilities, ranging from 14C calibrations to sophisticated interpolation tools. Using CSciBox's GUI, a scientist can build custom analysis pipelines by composing these built-in components or adding new ones. Alternatively, she can employ CSciBox's automated reasoning engine, Hobbes, which uses AI techniques to perform an in-depth, autonomous exploration of the space of possible age-depth models and presents the results—both the models and the reasoning that was used in constructing and evaluating them—to the user for her inspection. Hobbes accomplishes this using a rulebase that captures the knowledge of expert geoscientists, which was collected over the course of more than 100 hours of interviews. It works by using these rules to generate arguments for and against different age-depth model choices for a given core. Given a marine-sediment record containing uncalibrated 14C dates, for instance, Hobbes tries CALIB-style calibrations using a choice of IntCal curves, with reservoir age correction values chosen from the 14CHRONO database using the lat/long information provided with the core, and finally composes the resulting age points into a full age model using different interpolation methods. It evaluates each model—e.g., looking for outliers or reversals—and uses that information to guide the next steps of its exploration, and presents the results to the user in human-readable form. The most powerful of CSciBox's built-in interpolation methods is BACON, a Bayesian sedimentation-rate algorithm—a powerful but complex tool that can be difficult to use. Hobbes adjusts BACON's many parameters autonomously to match the age model to the expectations of expert geoscientists, as captured in its rulebase. It then checks the model against the data and iteratively re-calculates until it is a good fit to the data.

  14. Comparative Assessment of Stabilised Polybutadiene Binder under Accelerated Ageing

    Directory of Open Access Journals (Sweden)

    Luiz Felipe Cannaval Sbegue

    2016-04-01

    Full Text Available Polybutadiene elastomers are versatile materials, being employed at several applications from rocket propellant binder to adhesives and sealants. The elastomers derived from hydroxyl-terminated polybutadiene are usually stabilised with antioxidants to prevent degradation. In this study, a comparative assessment among 2,2’-methylene-bis (4-methyl-6-tert-butylphenol (AO2246, 2,6-di-tert-butyl-4-methylphenol (BHT, p-phenylenediamine (pPDA, and triphenylphosphine (TPP regarding stabilisation of hydroxyl-terminated polybutadiene binder under accelerated ageing (six months at 65 °C was carried out. Evaluation of antioxidants effectiveness was examined through Oxidation Induction time, sol/gel extraction, swelling and mechanical testing, dynamic mechanical analysis, and mass variation measurement. AO2246 yielded the best performance, meanwhile BHT was poorly protective. TPP acted as prooxidant, causing a severe degradation of the binder, and pPDA was not manageable to be assessed due to the lower curing degree of the resulted polyurethane.

  15. Accelerated aging studies and environmental stability of prototype tamper tapes

    Energy Technology Data Exchange (ETDEWEB)

    Wright, B.W.; Wright, C.W. [Pacific Northwest Lab., Richland, WA (United States); Bunk, A.R. [Battelle Columbus Lab., OH (United States)] [and others

    1995-05-01

    This report describes the results of accelerated aging experiments (weathering) conducted on prototype tamper tapes bonded to a variety of surface materials. The prototype tamper tapes were based on the patented Confirm{reg_sign} tamper-indicating technology developed and produced by 3M Company. Tamper tapes bonded to surfaces using pressure sensitive adhesive (PSA) and four rapid-set adhesives were evaluated. The configurations of the PSA-bonded tamper tapes were 1.27-cm-wide Confirm{reg_sign} 1700 windows with vinyl underlay and 2.54-cm-wide Confirm{reg_sign} 1700 windows with vinyl and polyester underlays. The configurations of the rapid-set adhesive-bonded tamper tapes were 2.54-cm-wide Confirm{reg_sign} (1700, 1500 with and without primer, and 1300) windows with vinyl underlay. Surfaces used for bonding included aluminum, steel, stainless steel, Kevlar{reg_sign}, brass, copper, fiberglass/resin with and without gel coat, polyurethane-painted steel, acrylonitrile:butadiene:styrene plastic, polyester fiberglass board, Lexan polycarbonate, and cedar wood. Weathering conditions included a QUV cabinet (ultraviolet light at 60{degrees}C, condensing humidity at 40{degrees}C), a thermal cycling cabinet (-18{degrees}C to 46{degrees}C), a Weather-O-Meter (Xenon lamp), and exposure outdoors in Daytona Beach, Florida. Environmental aging exposures lasted from 7 weeks to 5 months. After exposure, the tamper tapes were visually examined and tested for transfer resistance. Tamper tapes were also exposed to a variety of chemical liquids (including organic solvents, acids, bases, and oxidizing liquids) to determine chemical resistance and to sand to determine abrasion resistance.

  16. [The use of biological age on mental work capacity model in accelerated aging assessment of professional lorry-drivers].

    Science.gov (United States)

    Bashkireva, A S

    2012-01-01

    The studies of biological age, aging rate, mental work capacity in professional drivers were conducted. The examination revealed peculiarities of system organization of functions determining the mental work capacity levels. Dynamics of the aging process of professional driver's organism in relation with calendar age and driving experience were shown using the biological age model. The results point at the premature decrease of the mental work capacity in professional drivers. It was proved, that premature age-related changes of physiologic and psychophysiologic indices in drivers are just "risk indicators", while long driving experience is a real risk factor, accelerating the aging process. The "risk group" with manifestations of accelerating aging was observed in 40-49-year old drivers with 15-19 years of professional experience. The expediency of using the following methods for the age rate estimation according to biologic age indices and necessity of prophylactic measures for premature and accelerated aging prevention among working population was demonstrated.

  17. Efficiency and durability of a self-cleaning coating on concrete and stones under both natural and artificial ageing trials

    Science.gov (United States)

    Carmona-Quiroga, P. M.; Martínez-Ramírez, S.; Viles, H. A.

    2018-03-01

    This study aimed to test the performance under long-term working conditions of a commercial self-cleaning coating, a water-based TiO2 sol, on three building materials important in recent and older European heritage; Portland limestone, Woodkirk sandstone and concrete. First, the compatibility of the coating (effect on petrophysical properties) with the substrates was demonstrated by examining aesthetic properties and water vapour permeability of the building materials and secondly, the self-cleaning ability of the TiO2 nanoparticles in degrading artificial stain (rhodamine B) under UV light was evaluated. Finally, the durability (lasting performance) of photocatalytic activity was assessed during one year of outdoor exposure trial and 2000 h of accelerated ageing in a chamber with UV radiation and condensation cycles. Results showed that photocatalytic activity was unaltered on concrete, whereas on sandstone, particularly after artificial ageing, it was reduced due to the removal of nanoparticles from the surface. On limestone, a decrease of TiO2 content was observed but photodegradation efficiency (ability to perform as self-cleaner) seemed not to be affected.

  18. Effect of Accelerated Aging on Color Change of Direct and Indirect Fiber-Reinforced Composite Restorations

    Directory of Open Access Journals (Sweden)

    Masomeh Hasani Tabatabaei

    2016-10-01

    Full Text Available Objectives: The aim of this study was to assess the effect of artificial accelerated aging (AAA on color change of direct and indirect fiber-reinforced composite (FRC restorations.Materials and Methods: Direct (Z250 and indirect (Gradia composite resins were reinforced with glass (GF and polyethylene fibers (PF based on the manufacturers’ instructions. Forty samples were fabricated and divided into eight groups (n=5. Four groups served as experimental groups and the remaining four served as controls. Color change (∆E and color parameters (∆L*, ∆a*, ∆b* were read at baseline and after AAA based on the CIELAB system. Three-way ANOVA and Tukey’s test were used for statistical analysis.Results: Significant differences were found in ΔE, ΔL*, Δa* and Δb* among the groups after AAA (P<0.05. Most of the studied samples demonstrated an increase in lightness and a red-yellow shift after AAA.Conclusions: The obtained ∆E values were unacceptable after AAA (∆E≥ 3.3. All indirect samples showed a green-blue shift with a reduction in lightness except for Gradia/PF+ NuliteF.Keywords: Aging; Composite Resins; Color

  19. Color stability of maxillofacial silicone with nanoparticle pigment and opacifier submitted to disinfection and artificial aging.

    Science.gov (United States)

    Filié Haddad, Marcela; Coelho Goiato, Marcelo; Micheline Dos Santos, Daniela; Moreno, Amália; Filipe D'almeida, Nuno; Alves Pesqueira, Aldiéris

    2011-09-01

    The purpose of this study was to evaluate the color stability of a maxillofacial elastomer with the addition of a nanoparticle pigment and∕or an opacifier submitted to chemical disinfection and artificial aging. Specimens were divided into four groups (n = 30): group I: silicone without pigment or opacifier, group II: ceramic powder pigment, group III: Barium sulfate (BaSO(4)) opacifier, and group IV: ceramic powder and BaSO(4) opacifier. Specimens of each group (n = 10) were disinfected with effervescent tablets, neutral soap, or 4% chlorhexidine gluconate. Disinfection was done three times a week during two months. Afterward, specimens were submitted to different periods of artificial aging. Color evaluation was initially done, after 60 days (disinfection period) and after 252, 504, and 1008 h of artificial aging with aid of a reflection spectrophotometer. Data were analyzed by three-way ANOVA and Tukey test (α = 0.05). The isolated factor disinfection did not statistically influence the values of color stability among groups. The association between pigment and BaSO(4) opacifier (GIV) was more stable in relationship to color change (△E). All values of △E obtained, independent of the disinfectant and the period of artificial aging, were considered acceptable in agreement with the norms presented in literature.

  20. Thermophysical properties of cement based composites and their changes after artificial ageing

    Science.gov (United States)

    Šín, Peter; Pavlendová, Gabriela; Lukovičová, Jozefa; Kopčok, Michal

    2017-07-01

    The usage of recycled plastic materials in concrete mix gained increased attention. The behaviour of such environmental friendly material is studied. In this paper an investigation of the thermophysical properties of cement based composites containing plastic waste particles with different percentage is presented. Measurements were carried out using pulse transient method before and after artificial ageing in climatic chamber BINDER MKF (E3).

  1. Influence of artificial aging in marginal adaptation of mixed class V cavities.

    Science.gov (United States)

    Tonetto, Mateus Rodrigues; Bandéca, Matheus Coelho; Barud, Hélida Gomes de Oliveira; Pinto, Shelon Cristina Souza; Lima, Darlon Martins; Borges, Alvaro Henrique; de Campos, Edson Alves; de Andrade, Marcelo Ferrarezi

    2013-03-01

    The aim of this study was to investigate whether the artificial aging by thermal cycling had influenced the marginal adaptation of class V restorations with/without chlorhexidine application in the bond process. Twelve intact human third molars were used. Class V cavity preparations were performed on the buccal surface and the teeth received 35% phosphoric acid-etching procedure (Ultradent Products Inc., South Jordan, Utah, USA). Subsequently, the samples were divided in two groups: Untreated acid-etched dentin and chlorhexidine application as an adjunct in the bond process. The adhesive Single Bond 2 (3M ESPE, St. Paul, MN, USA) was used after 2% chlorhexidine application, and the restorations were performed with Filtek™ Z350 XT (3M ESPE) composite resin. The specimens were submitted to artificial aging by thermal cycling with 3,000 cycles. Analyzes were performed on scanning electron microscopy using replicas of marginal adaptation in percentage of continuous margin before and after the artificial aging. The data were analyzed by paired test and the results showed statistically significant differences in the percentage of continuous margin with/without chlorhexidine treatment before and after thermal cycling. This study concluded that the artificial aging by thermal cycling influenced the marginal adaptation of mixed class V composite restorations.

  2. Investigation of mechanical properties of modern dental composites after artificial aging for one year.

    Science.gov (United States)

    Hahnel, Sebastian; Henrich, Anne; Bürgers, Ralf; Handel, Gerhard; Rosentritt, Martin

    2010-01-01

    This in vitro study investigated the aging behavior of dental composites with regard to surface roughness (SR), Vickers hardness (VH) and flexural strength (FS), and the study elucidated the impact of artificial aging parameters. One hundred and sixty-five rectangular specimens were prepared from five composites (Filtek Supreme XT, Filtek Silorane, CeramX, Quixfil, experimental ormocer) and subjected to various artificial aging protocols (storage in distilled water/ethanol/artificial saliva for 7, 90 and 365 days; thermal cycling, 2 x 3000 cycles 5/55 degrees C). SR, VH and FS were determined at baseline and after each aging treatment. Means and standard deviations were calculated; statistical analysis was performed using three-way ANOVA and the Tukey-Kramer multiple comparison test (alpha=.05). The results showed a significant influence in the composite and aging duration on mechanical parameters; the aging medium did not have a significant influence on VH and FS, but there was a significant influence on SR. The highest overall VH was found for theexperimental ormocer; Filtek Silorane yielded the lowest values. For FS, the significantly highest values were found for Filtek Silorane, and the lowest values were found for the experimental ormocer. Prolonged aging periods (90 or 365 days) or thermal cycling led to significant decreases in both VH and FS and significant increases in SR. The findings of the current study indicate that composites differ significantly for SR and its mechanical properties with regard to FS and VH, as well as in aging behavior. Generally, artificial aging leads to a significant decrease in mechanical properties, which underlines the relevance of continuous improvement of dental composites.

  3. Can we accelerate medicinal chemistry by augmenting the chemist with Big Data and artificial intelligence?

    Science.gov (United States)

    Griffen, Edward J; Dossetter, Alexander G; Leach, Andrew G; Montague, Shane

    2018-03-22

    AI comes to lead optimization: medicinal chemistry in all disease areas can be accelerated by exploiting our pre-competitive knowledge in an unbiased way. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Maternal consumption of artificially sweetened beverages during pregnancy, and offspring growth through 7 years of age

    DEFF Research Database (Denmark)

    Zhu, Yeyi; Olsen, Sjurdur F; Mendola, Pauline

    2017-01-01

    Background: Artificial sweeteners are widely replacing caloric sweeteners. Data on long-term impact of artificially sweetened beverage (ASB) consumption during pregnancy on offspring obesity risk are lacking. We prospectively investigated intake of ASBs and sugar-sweetened beverages (SSBs) during...... pregnancy in relation to offspring growth through age 7 years among high-risk children born to women with gestational diabetes. Methods: In a prospective study of 918 mother-singleton child dyads from the Danish National Birth Cohort, maternal dietary intake was assessed by a food frequency questionnaire...

  5. Accelerator mass spectrometry (AMS) dating from the modern age to the past million age

    International Nuclear Information System (INIS)

    Sasa, K.; Nagashima, Y.; Seki, R.; Takahashi, T.; Tosaki, Y.; Sueki, K.; Bessyo, K.; Matsumura, H.; Miura, T.

    2006-01-01

    A multi-nuclide Accelerator Mass Spectrometry system at the University of Tsukuba (Tsukuba AMS system) is able to measure the long-lived radioisotopes of 14 C, 26 Al, 36 Cl and 129 I. The Tsukuba AMS system is able to perform AMS measurements with the terminal voltage of more than 10 MV. It is difficult to estimate the modern age dating (timescale of the past ten years) by the AMS dating method because the low attenuation of long-lived radioisotopes. The atomic bomb-produced radioisotopes are proposed as the environmental traces for the modern age dating. There is the advantage that the long half life of radioisotopes makes the attenuation negligilbe compared with the short half life of radioisotopes. We applied the 36 Cl bomb pulse as a dating tool for modern groundwater (∼50 years) instead of the 3 H bomb pulse. In addition, we have developed 32 Si-AMS system. The half life of 32 Si is about 140 years, therefore 32 Si-AMS is a useful tool for the modern age dating. On the other hand, we have started a new project to measure the cosmogenic nuclide of 36 Cl in an ice core retrieved from Dome Fuji station at Antarctic in order to investigate the past solar activity and the past earth environment as the timescale of the past million age. (author)

  6. Traumatic stress and accelerated DNA methylation age: A meta-analysis.

    Science.gov (United States)

    Wolf, Erika J; Maniates, Hannah; Nugent, Nicole; Maihofer, Adam X; Armstrong, Don; Ratanatharathorn, Andrew; Ashley-Koch, Allison E; Garrett, Melanie; Kimbrel, Nathan A; Lori, Adriana; Va Mid-Atlantic Mirecc Workgroup; Aiello, Allison E; Baker, Dewleen G; Beckham, Jean C; Boks, Marco P; Galea, Sandro; Geuze, Elbert; Hauser, Michael A; Kessler, Ronald C; Koenen, Karestan C; Miller, Mark W; Ressler, Kerry J; Risbrough, Victoria; Rutten, Bart P F; Stein, Murray B; Ursano, Robert J; Vermetten, Eric; Vinkers, Christiaan H; Uddin, Monica; Smith, Alicia K; Nievergelt, Caroline M; Logue, Mark W

    2018-06-01

    Recent studies examining the association between posttraumatic stress disorder (PTSD) and accelerated aging, as defined by DNA methylation-based estimates of cellular age that exceed chronological age, have yielded mixed results. We conducted a meta-analysis of trauma exposure and PTSD diagnosis and symptom severity in association with accelerated DNA methylation age using data from 9 cohorts contributing to the Psychiatric Genomics Consortium PTSD Epigenetics Workgroup (combined N = 2186). Associations between demographic and cellular variables and accelerated DNA methylation age were also examined, as was the moderating influence of demographic variables. Meta-analysis of regression coefficients from contributing cohorts revealed that childhood trauma exposure (when measured with the Childhood Trauma Questionnaire) and lifetime PTSD severity evidenced significant, albeit small, meta-analytic associations with accelerated DNA methylation age (ps = 0.028 and 0.016, respectively). Sex, CD4T cell proportions, and natural killer cell proportions were also significantly associated with accelerated DNA methylation age (all ps age. There was no evidence of moderation of the trauma or PTSD variables by demographic factors. Results suggest that traumatic stress is associated with advanced epigenetic age and raise the possibility that cells integral to immune system maintenance and responsivity play a role in this. This study highlights the need for additional research into the biological mechanisms linking traumatic stress to accelerated DNA methylation age and the importance of furthering our understanding of the neurobiological and health consequences of PTSD. Published by Elsevier Ltd.

  7. Numerical Simulation of Mechanical Property of Post Friction Stir Weld Artificial Ageing of Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    WAN Zhenyu

    2017-08-01

    Full Text Available KWN model was used to establish the precipitation evolution model of friction stir welding of Al-Mg-Si alloy. The yield strength was divided into three parts:the contribution from grain size, the contribution from solid solution and the contribution from the precipitations. Based on this model, the yield strength and hardness of friction stir weld was predicted. The effect of post weld artificial ageing on mechanical properties of friction stir weld was further investigated. The results indicate that longer holding time can be beneficial to the recovery of mechanical properties in the stirring zone. Higher temperature can lead to quick recovery of mechanical properties in the stirring zone, but when the holding temperature is higher than 200℃, longer holding time can lead the base metal softened, which is harmful to the service of friction stir welds. The mechanical property in the heat affected zone cannot be improved by post weld artificial ageing.

  8. Artificially accelerating the reversal of desertification: cyanobacterial inoculation facilitates the succession of vegetation communities.

    Science.gov (United States)

    Lan, Shubin; Zhang, Qingyi; Wu, Li; Liu, Yongding; Zhang, Delu; Hu, Chunxiang

    2014-01-01

    Desertification has been recognized as a global environmental problem, and one region experiencing ongoing desertification is the eastern edge of Qubqi Desert (Inner Mongolia). To investigate the facilitating effects of cyanobacterial inoculation technology on the desertification control along this steppe-desert transition region, artificial cyanobacterial crusts were constructed with two filamentous cyanobacteria 3 and 8 years ago combined with Salix planting. The results showed that no crusts formed after 3 years of fixation only with Salix planting, whereas after cyanobacterial inoculation, the crusts formed quickly and gradually succeed to moss crusts. During that course, topsoil environments were gradually improved, providing the necessary material basis for the regeneration of vascular plants. In this investigation, total 27 species of vascular plants had regenerated in the experimental region, mainly belonging to Asteraceae, Poaceae, Chenopodiaceae and Leguminosae. Using space time substitution, the dominant species along with the application of cyanobacterial inoculation technology succeeded from Agriophyllum squarrosum ultimately to Leymus chinensis. In addition, it was found that the shady side of the dunes is more conducive to crust development and succession of vegetation communities. Conclusively, our results indicate artificial cyanobacterial inoculation technology is an effective and desirable path for desertification control.

  9. Converging blockchain and next-generation artificial intelligence technologies to decentralize and accelerate biomedical research and healthcare

    Science.gov (United States)

    Mamoshina, Polina; Ojomoko, Lucy; Yanovich, Yury; Ostrovski, Alex; Botezatu, Alex; Prikhodko, Pavel; Izumchenko, Eugene; Aliper, Alexander; Romantsov, Konstantin; Zhebrak, Alexander; Ogu, Iraneus Obioma; Zhavoronkov, Alex

    2018-01-01

    The increased availability of data and recent advancements in artificial intelligence present the unprecedented opportunities in healthcare and major challenges for the patients, developers, providers and regulators. The novel deep learning and transfer learning techniques are turning any data about the person into medical data transforming simple facial pictures and videos into powerful sources of data for predictive analytics. Presently, the patients do not have control over the access privileges to their medical records and remain unaware of the true value of the data they have. In this paper, we provide an overview of the next-generation artificial intelligence and blockchain technologies and present innovative solutions that may be used to accelerate the biomedical research and enable patients with new tools to control and profit from their personal data as well with the incentives to undergo constant health monitoring. We introduce new concepts to appraise and evaluate personal records, including the combination-, time- and relationship-value of the data. We also present a roadmap for a blockchain-enabled decentralized personal health data ecosystem to enable novel approaches for drug discovery, biomarker development, and preventative healthcare. A secure and transparent distributed personal data marketplace utilizing blockchain and deep learning technologies may be able to resolve the challenges faced by the regulators and return the control over personal data including medical records back to the individuals. PMID:29464026

  10. Converging blockchain and next-generation artificial intelligence technologies to decentralize and accelerate biomedical research and healthcare.

    Science.gov (United States)

    Mamoshina, Polina; Ojomoko, Lucy; Yanovich, Yury; Ostrovski, Alex; Botezatu, Alex; Prikhodko, Pavel; Izumchenko, Eugene; Aliper, Alexander; Romantsov, Konstantin; Zhebrak, Alexander; Ogu, Iraneus Obioma; Zhavoronkov, Alex

    2018-01-19

    The increased availability of data and recent advancements in artificial intelligence present the unprecedented opportunities in healthcare and major challenges for the patients, developers, providers and regulators. The novel deep learning and transfer learning techniques are turning any data about the person into medical data transforming simple facial pictures and videos into powerful sources of data for predictive analytics. Presently, the patients do not have control over the access privileges to their medical records and remain unaware of the true value of the data they have. In this paper, we provide an overview of the next-generation artificial intelligence and blockchain technologies and present innovative solutions that may be used to accelerate the biomedical research and enable patients with new tools to control and profit from their personal data as well with the incentives to undergo constant health monitoring. We introduce new concepts to appraise and evaluate personal records, including the combination-, time- and relationship-value of the data. We also present a roadmap for a blockchain-enabled decentralized personal health data ecosystem to enable novel approaches for drug discovery, biomarker development, and preventative healthcare. A secure and transparent distributed personal data marketplace utilizing blockchain and deep learning technologies may be able to resolve the challenges faced by the regulators and return the control over personal data including medical records back to the individuals.

  11. Rapid Analyses of Polyetheretherketone Wear Characteristics by Accelerated Wear Testing with Microfabricated Surfaces for Artificial Joint Systems.

    Science.gov (United States)

    Su, Chen-Ying; Kuo, Chien-Wei; Fang, Hsu-Wei

    2017-01-01

    Wear particle-induced biological responses are the major factors resulting in the loosening and then failure of total joint arthroplasties. It is feasible to improve the lubrication and reduce the wear of artificial joint system. Polyetheretherketone (PEEK) is considered as a potential bearing material due to its mechanical characteristics of resistance to fatigue strain. The PEEK wear particles have been indicated to be involved in biological responses in vitro, and further studies regarding the wear phenomena and wear particle generation are needed. In this study, we have established an accelerated wear testing system with microfabricated surfaces. Various contact pressures and lubricants have been utilized in the accelerated wear tests. Our results showed that increasing contact pressure resulted in an increase of wear particle sizes and wear rate, and the size of PEEK wear particles can be controlled by the feature size of microfabricated surfaces. These results provided the information rapidly about factors that affect the morphology and amount of PEEK wear particles and can be applied in the future for application of PEEK on the biological articulation system.

  12. Testing the hypothesis of accelerated cerebral white matter aging in schizophrenia and major depression.

    Science.gov (United States)

    Kochunov, Peter; Glahn, David C; Rowland, Laura M; Olvera, Rene L; Winkler, Anderson; Yang, Yi-Hong; Sampath, Hemalatha; Carpenter, Will T; Duggirala, Ravindranath; Curran, Joanne; Blangero, John; Hong, L Elliot

    2013-03-01

    Elevated rate of aging-related biological and functional decline, termed "accelerated aging," is reported in patients with schizophrenia (SCZ) and major depressive disorder (MDD). We used diffusion tensor imaging derived fractional anisotropy (FA) as a biomarker of aging-related decline in white matter (WM) integrity to test the hypotheses of accelerated aging in SCZ and MDD. The SCZ cohort comprised 58 SCZ patients and 60 controls (aged 20-60 years). The MDD cohort comprised 136 MDD patients and 351 controls (aged 20-79 years). The main outcome measures were the diagnosis-by-age interaction on whole-brain-averaged WM FA values and FA values from 12 major WM tracts. Diagnosis-by-age interaction for the whole-brain average FA was significant for the SCZ (p = .04) but not the MDD (p = .80) cohort. Diagnosis-by-age interaction was nominally significant (paccelerated aging in SCZ but not in MDD, suggesting some difference in the pathophysiology underlying their WM aging changes. Tract-specific heterochronicity of WM development modulated presentation of accelerated aging in SCZ: WM tracts that matured later in life appeared more sensitive to the pathophysiology of SCZ and demonstrated more susceptibility to disorder-related accelerated decline in FA values with age. This trend was not observed in MDD cohort. Copyright © 2013 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  13. Delayed and accelerated aging share common longevity assurance mechanisms

    NARCIS (Netherlands)

    Schumacher, B.; van der Pluijm, I.; Moorhouse, M.J.; Kosteas, T.; Robinson, A.R.; Suh, Y.; Breit, T.M.; van Steeg, H.; Niedernhofer, L.J.; van IJcken, W.; Bartke, A.; Spindler, S.R.; Hoeijmakers, J.H.J.; van der Horst, G.T.J.; Garinis, G.A.

    2008-01-01

    Mutant dwarf and calorie-restricted mice benefit from healthy aging and unusually long lifespan. In contrast, mouse models for DNA repair-deficient progeroid syndromes age and die prematurely. To identify mechanisms that regulate mammalian longevity, we quantified the parallels between the

  14. Delayed and accelerated aging share common longevity assurance mechanisms

    NARCIS (Netherlands)

    B. Schumacher (Björn); I. van der Pluijm (Ingrid); M.J. Moorhouse (Michael); T. Kosteas (Theodore); A.R. Robinson (Andria Rasile); Y. Suh (Yousin); T.M. Breit (Timo); H. van Steeg (Harry); L.J. Niedernhofer (Laura); W.F.J. van IJcken (Wilfred); A. Bartke (Andrzej); S.R. Spindler (Stephen); J.H.J. Hoeijmakers (Jan); G.T.J. van der Horst (Gijsbertus); G.A. Garinis (George)

    2008-01-01

    textabstractMutant dwarf and calorie-restricted mice benefit from healthy aging and unusually long lifespan. In contrast, mouse models for DNA repair-deficient progeroid syndromes age and die prematurely. To identify mechanisms that regulate mammalian longevity, we quantified the parallels between

  15. Chronic inflammation induces telomere dysfunction and accelerates ageing in mice

    NARCIS (Netherlands)

    Jurk, Diana; Wilson, Caroline; Passos, Joao F.; Oakley, Fiona; Correia-Melo, Clara; Greaves, Laura; Saretzki, Gabriele; Fox, Chris; Lawless, Conor; Anderson, Rhys; Hewitt, Graeme; Pender, Sylvia L. F.; Fullard, Nicola; Nelson, Glyn; Mann, Jelena; van de Sluis, Bart; Mann, Derek A.; von Zglinicki, Thomas

    Chronic inflammation is associated with normal and pathological ageing. Here we show that chronic, progressive low-grade inflammation induced by knockout of the nfkb1 subunit of the transcription factor NF-kappa B induces premature ageing in mice. We also show that these mice have reduced

  16. Coenzyme Q10 prevents accelerated cardiac aging in a rat model of poor maternal nutrition and accelerated postnatal growth★

    OpenAIRE

    Tarry-Adkins, Jane L.; Blackmore, Heather L.; Martin-Gronert, Malgorzata S.; Fernandez-Twinn, Denise S.; McConnell, Josie M.; Hargreaves, Iain P.; Giussani, Dino A.; Ozanne, Susan E.

    2013-01-01

    Studies in human and animals have demonstrated that nutritionally induced low birth-weight followed by rapid postnatal growth increases the risk of metabolic syndrome and cardiovascular disease. Although the mechanisms underlying such nutritional programming are not clearly defined, increased oxidative-stress leading to accelerated cellular aging has been proposed to play an important role. Using an established rodent model of low birth-weight and catch-up growth, we show here that post-weani...

  17. Influence of pigments and opacifiers on color stability of an artificially aged facial silicone.

    Science.gov (United States)

    dos Santos, Daniela Micheline; Goiato, Marcelo Coelho; Moreno, Amália; Pesqueira, Aldiéris Alves; Haddad, Marcela Filiè

    2011-04-01

    The aim of this study was to evaluate the influence of two pigments (ceramic powder and oil paint) and one opacifier (barium sulfate) on the color stability of MDX4-4210 facial silicone submitted to accelerated aging. Sixty specimens of silicone were fabricated and divided into six groups--colorless (G1), colorless with opacifier (G2), ceramic (G3), ceramic with opacifier (G4), oil (G5), oil with opacifier (G6). All replicas were submitted to accelerated aging for 1008 hours. The evaluations of chromatic alteration through visual analysis and reflection spectrophotometry were carried out initially and after 252, 504, and 1008 hours of aging. The results were submitted to ANOVA and Tukey's test at 5% level of significance. All groups exhibited chromatic alteration (ΔE > 0); however, this color alteration was not perceptible through visual analysis of the color. The pigmented groups with opacifier presented the lowest ΔE values, with a statistical difference from the other groups. For the groups without opacifier, the group pigmented with oil paint exhibited the lowest ΔE values in the different aging periods, with a statistical difference. Accelerated aging generated significant chromatic alterations in all groups after 252 hours, except for the colorless and oil groups, both with opacifier (G2 and G6). The opacifier protects facial silicones against color degradation, and oil paint is a stable pigment even without addition of opacifier. © 2010 by The American College of Prosthodontists.

  18. Accelerating progress in Artificial General Intelligence: Choosing a benchmark for natural world interaction

    Science.gov (United States)

    Rohrer, Brandon

    2010-12-01

    Measuring progress in the field of Artificial General Intelligence (AGI) can be difficult without commonly accepted methods of evaluation. An AGI benchmark would allow evaluation and comparison of the many computational intelligence algorithms that have been developed. In this paper I propose that a benchmark for natural world interaction would possess seven key characteristics: fitness, breadth, specificity, low cost, simplicity, range, and task focus. I also outline two benchmark examples that meet most of these criteria. In the first, the direction task, a human coach directs a machine to perform a novel task in an unfamiliar environment. The direction task is extremely broad, but may be idealistic. In the second, the AGI battery, AGI candidates are evaluated based on their performance on a collection of more specific tasks. The AGI battery is designed to be appropriate to the capabilities of currently existing systems. Both the direction task and the AGI battery would require further definition before implementing. The paper concludes with a description of a task that might be included in the AGI battery: the search and retrieve task.

  19. Some applications of AI [Artificial Intelligence] to the problems of accelerator physics

    International Nuclear Information System (INIS)

    Higo, T.; Shoaee, H.; Spencer, J.E.

    1986-09-01

    Failure of orbit correction schemes to recognize betatron oscillation patterns obvious to any machine operator is a good problem with which to analyze the uses of Artificial Intelligence and the roles and relationships of operators, control systems and machines. Because such error modes are very common, their generalization could provide an efficient machine optimization and control strategy. A set of first-order, unitary transformations connecting canonical variables through measured results are defined which can either be compared to design for commissioning or to past results for 'golden orbit' operation. Because these relate directly to hardware variables, the method is simple, fast and direct. It has implications for machine design, controls, monitoring and feedback. Chronological analysis of such machine signatures can predict or provide a variety of information such as mean time to failure, failure modes and fast feedback or feedforward for optimizing figures of merit such as luminosity or current transmission. The use of theoretical and empirical scaling relations for such problems is discussed in terms of various figures of merit, the variables on which they depend as well as their functional dependences

  20. Effect of accelerated aging on translucency of monolithic zirconia

    Directory of Open Access Journals (Sweden)

    O. Abdelbary

    2016-12-01

    Conclusion: Thickness of zirconia has significant effect on translucency. Aging has significant effect on thinner sections of zirconia. More research is required on zirconia towards making the material more translucent for its potential use as esthetic monolithic restoration.

  1. Forming characteristics of artificial aging Al-Mg-Si-Cu sheet alloys

    Science.gov (United States)

    Klos, Artur; Kellner, Sven; Wortberg, Daniel; Walter, Philipp; Bassi, Corrado; Merklein, Marion

    2017-10-01

    AA6111 is a commonly used aluminum alloy for body-in-white (BIW) components with good bake-hardening response, high strength and excellent formability. For industrial applications various process strategies are considered to reach strength of about 250 MPa in the final body part with that type of alloy. The purpose of this paper is to discuss recent process strategies of high-strength AA6111 sheets to evaluate the forming characteristics, precipitation kinetics dissolution and mechanical properties in the final condition. The forming behavior is investigated by four potential process chains after single-stage or multi-stage heat treatment including T4 (pre-aged at > 80 °C after quenching), T61 (T4 + artificial aged at 120-150 °C for 10-18 h), T6 (T4 + artificial aged at 180-220°C up to 12 h) and PFHT (T4 + post form heat treatment at 205°C for 30 min). The experimental input for characterization of the formability consists of tensile tests, bending tests and drawing tests. Differential Scanning Calorimetry (DSC) is used, to correlate the forming behavior with the precipitation distribution in the advanced stages of aging. The study shows that the forming behavior is strongly dependent on the condition the alloy.

  2. Accelerated optimizations of an electromagnetic acoustic transducer with artificial neural networks as metamodels

    Directory of Open Access Journals (Sweden)

    S. Wang

    2017-08-01

    Full Text Available Electromagnetic acoustic transducers (EMATs are noncontact transducers generating ultrasonic waves directly in the conductive sample. Despite the advantages, their transduction efficiencies are relatively low, so it is imperative to build accurate multiphysics models of EMATs and optimize the structural parameters accordingly, using a suitable optimization algorithm. The optimizing process often involves a large number of runs of the computationally expensive numerical models, so metamodels as substitutes for the real numerical models are helpful for the optimizations. In this work the focus is on the artificial neural networks as the metamodels of an omnidirectional EMAT, including the multilayer feedforward networks trained with the basic and improved back propagation algorithms and the radial basis function networks with exact and nonexact interpolations. The developed neural-network programs are tested on an example problem. Then the model of an omnidirectional EMAT generating Lamb waves in a linearized steel plate is introduced, and various approaches to calculate the amplitudes of the displacement component waveforms are discussed. The neural-network metamodels are then built for the EMAT model and compared to the displacement component amplitude (or ratio of amplitudes surface data on a discrete grid of the design variables as the reference, applying a multifrequency model with FFT (fast Fourier transform/IFFT (inverse FFT processing. Finally the two-objective optimization problem is formulated with one objective function minimizing the ratio of the amplitude of the S0-mode Lamb wave to that of the A0 mode, and the other objective function minimizing as the negative amplitude of the A0 mode. Pareto fronts in the criterion space are solved with the neural-network models and the total time consumption is greatly decreased. From the study it could be observed that the radial basis function network with exact interpolation has the best

  3. Comportamento de fungos e de sementes de feijoeiro durante o teste de envelhecimento artificial Behavior of fungi and of bean seeds during the artificial aging test

    Directory of Open Access Journals (Sweden)

    MONALISA ALVES DINIZ DA SILVA

    2000-03-01

    Full Text Available O teste de envelhecimento artificial, recomendado para avaliar o vigor de lotes de sementes, apresenta variabilidade em seus resultados; a ação dos fungos é considerada uma das causas dessa variabilidade. Este trabalho objetivou verificar os efeitos de diferentes períodos de envelhecimento artificial, no comportamento fisiológico de sementes do feijoeiro e dos fungos Aspergillus spp., Penicillium spp., Fusarium oxysporum e Colletotrichum lindemuthianum, inoculados artificialmente. Foram conduzidos testes de sanidade, germinação, tetrazólio, emergência, condutividade elétrica e lixiviação de potássio. As respostas obtidas, dependentes da duração do período de envelhecimento, indicaram efeitos da espécie fúngica presente. Concluiu-se que o teste de envelhecimento artificial associa a expressão de causas fisiológicas e sanitárias, o que prejudica a interpretação dos dados obtidos; a presença de fungos, principalmente de Aspergillus spp., pode ser considerada como capaz de interferir de modo negativo no desempenho das sementes envelhecidas artificialmente.Although recommended for evaluation of seed lot vigor, artificial aging test shows results variability for reasons yet to be elucidated. Seed-fungi association is considered one of the causes responsible for such variation. The goal of this work was to verify the effects of periods of artificial aging on bean seed behavior and on Aspergillus spp., Penicillium spp., Fusarium oxysporum and Colletotrichum lindemuthianum fungi artificially inoculated by contact method. Health, germination, tetrazolium, emergence, electrical conductivity and potassium leaching tests were performed for seed behavior evaluation. The answers achieved, besides dependable on the aging time period, indicated the effect of fungi species associated to the seed. The artificial aging test was found to be associated with the expression of physiological and sanitary causes that interfere with data

  4. Accelerated aging, natural aging, and small punch testing of gamma-air sterilized polycarbonate urethane acetabular components.

    Science.gov (United States)

    Kurtz, S M; Siskey, R; Reitman, M

    2010-05-01

    The objectives of this study were three-fold: (1) to determine the applicability of the small punch test to characterize Bionate 80A polycarbonate urethane (PCU) acetabular implants; (2) to evaluate the susceptibility of PCU acetabular implants to exhibit degradation of mechanical behavior following gamma irradiation in air and accelerated aging; and (3) to compare the oxidation of gamma-air sterilized PCU following accelerated aging and 5 years of natural shelf aging. In addition to attenuated total reflectance-Fourier transform infrared spectroscopy, we also adapted a miniature specimen mechanical test, the small punch test, for the deformable PCU cups. Accelerated aging was performed using ASTM F2003, a standard test that represents a severe oxidative challenge. The results of this study suggest that the small punch test is sufficiently sensitive and reproducible to discriminate slight differences in the large-deformation mechanical behavior of Bionate 80A following accelerated aging. The gamma-air sterilized PCU had a reduction of 9% in ultimate load after aging. Five years of shelf aging had little effect on the mechanical properties of the PCU. Overall, our findings suggest that the Bionate 80A material has greater oxidative stability than ultra-high molecular weight polyethylene following gamma irradiation in air and exposure to a severe oxidative challenge. (c) 2010 Wiley Periodicals, Inc.

  5. Improving artificial forest biomass estimates using afforestation age information from time series Landsat stacks.

    Science.gov (United States)

    Liu, Liangyun; Peng, Dailiang; Wang, Zhihui; Hu, Yong

    2014-11-01

    China maintains the largest artificial forest area in the world. Studying the dynamic variation of forest biomass and carbon stock is important to the sustainable use of forest resources and understanding of the artificial forest carbon budget in China. In this study, we investigated the potential of Landsat time series stacks for aboveground biomass (AGB) estimation in Yulin District, a key region of the Three-North Shelter region of China. Firstly, the afforestation age was successfully retrieved from the Landsat time series stacks in the last 40 years (from 1974 to 2013) and shown to be consistent with the surveyed tree ages, with a root-mean-square error (RMSE) value of 4.32 years and a determination coefficient (R (2)) of 0.824. Then, the AGB regression models were successfully developed by integrating vegetation indices and tree age. The simple ratio vegetation index (SR) is the best candidate of the commonly used vegetation indices for estimating forest AGB, and the forest AGB model was significantly improved using the combination of SR and tree age, with R (2) values from 0.50 to 0.727. Finally, the forest AGB images were mapped at eight epochs from 1985 to 2013 using SR and afforestation age. The total forest AGB in seven counties of Yulin District increased by 20.8 G kg, from 5.8 G kg in 1986 to 26.6 G kg in 2013, a total increase of 360 %. For the persistent forest area since 1974, the forest AGB density increased from 15.72 t/ha in 1986 to 44.53 t/ha in 2013, with an annual rate of about 0.98 t/ha. For the artificial forest planted after 1974, the AGB density increased about 1.03 t/ha a year from 1974 to 2013. The results present a noticeable carbon increment for the planted artificial forest in Yulin District over the last four decades.

  6. Tidal acceleration of the moon deduced from observations of artificial satellites

    International Nuclear Information System (INIS)

    Goad, C.C.; Douglas, B.C.

    1977-01-01

    It is stated that the existence of an apparent latitude dependence of tidal friction has been demonstrated from perturbations of the inclinations of GEOS-1 and GEOS-2 satellites. This has been correctly explained as being due to neglect of ocean tide perturbations. Parameter values for some ocean tide components have been obtained from several satellites, but values for the M 2 tide, which gives rise to the dominant effect of the oceans on tidal acceleration of the moon, have not been published. It is stated that, using an improved method for computing mean parameters, the authors obtained an observation equation for the M 2 tide from the satellite 1967-92A, and applying this technique to the GEOS-3 satellite they obtained an additional observation equation for the M 2 tide. Solid and fluid tide effects on satellites cannot be separated, requiring the assumption of the solid tide amplitude and phase parameters for a fluid tide solution. Results are compared with earlier values. (U.K.)

  7. Huntington's disease accelerates epigenetic aging of human brain and disrupts DNA methylation levels.

    Science.gov (United States)

    Horvath, Steve; Langfelder, Peter; Kwak, Seung; Aaronson, Jeff; Rosinski, Jim; Vogt, Thomas F; Eszes, Marika; Faull, Richard L M; Curtis, Maurice A; Waldvogel, Henry J; Choi, Oi-Wa; Tung, Spencer; Vinters, Harry V; Coppola, Giovanni; Yang, X William

    2016-07-01

    Age of Huntington's disease (HD) motoric onset is strongly related to the number of CAG trinucleotide repeats in the huntingtin gene, suggesting that biological tissue age plays an important role in disease etiology. Recently, a DNA methylation based biomarker of tissue age has been advanced as an epigenetic aging clock. We sought to inquire if HD is associated with an accelerated epigenetic age. DNA methylation data was generated for 475 brain samples from various brain regions of 26 HD cases and 39 controls. Overall, brain regions from HD cases exhibit a significant epigenetic age acceleration effect (p=0.0012). A multivariate model analysis suggests that HD status increases biological age by 3.2 years. Accelerated epigenetic age can be observed in specific brain regions (frontal lobe, parietal lobe, and cingulate gyrus). After excluding controls, we observe a negative correlation (r=-0.41, p=5.5×10-8) between HD gene CAG repeat length and the epigenetic age of HD brain samples. Using correlation network analysis, we identify 11 co-methylation modules with a significant association with HD status across 3 broad cortical regions. In conclusion, HD is associated with an accelerated epigenetic age of specific brain regions and more broadly with substantial changes in brain methylation levels.

  8. Enzyme activity and seedling growth of soybean seeds under accelerated aging

    Directory of Open Access Journals (Sweden)

    Yadollhhi Nooshabadi S.J.

    2013-11-01

    Full Text Available Seed aging is the main problem of seed storage. Changes of bio-chemical and reduction of seedling growth are consequence of seed deterioration. An experiment was conducted to evaluate the effects of accelerated aging on soybean seed germination indexes and enzyme activity. Seeds were incubated in closed plastic boxes for the accelerated aging treatments. Three accelerate aging regimes were performed by placing seeds at 41°C and relative humidity (RH of 90-100 % for 0, 2, 4, 6 and 8 days periods. Our results showed that increasing aging duration resulted higher reduction in germination characteristics, catalase and ascorbate peroxidase. Germination percentage, means time to germination, germination index, normal seedling percentage and enzyme activity decrease significantly.

  9. Rapamycin suppresses brain aging in senescence-accelerated OXYS rats.

    Science.gov (United States)

    Kolosova, Nataliya G; Vitovtov, Anton O; Muraleva, Natalia A; Akulov, Andrey E; Stefanova, Natalia A; Blagosklonny, Mikhail V

    2013-06-01

    Cellular and organismal aging are driven in part by the MTOR (mechanistic target of rapamycin) pathway and rapamycin extends life span inC elegans, Drosophila and mice. Herein, we investigated effects of rapamycin on brain aging in OXYS rats. Previously we found, in OXYS rats, an early development of age-associated pathological phenotypes similar to several geriatric disorders in humans, including cerebral dysfunctions. Behavioral alterations as well as learning and memory deficits develop by 3 months. Here we show that rapamycin treatment (0.1 or 0.5 mg/kg as a food mixture daily from the age of 1.5 to 3.5 months) decreased anxiety and improved locomotor and exploratory behavior in OXYS rats. In untreated OXYS rats, MRI revealed an increase of the area of hippocampus, substantial hydrocephalus and 2-fold increased area of the lateral ventricles. Rapamycin treatment prevented these abnormalities, erasing the difference between OXYS and Wister rats (used as control). All untreated OXYS rats showed signs of neurodegeneration, manifested by loci of demyelination. Rapamycin decreased the percentage of animals with demyelination and the number of loci. Levels of Tau and phospho-Tau (T181) were increased in OXYS rats (compared with Wistar). Rapamycin significantly decreased Tau and inhibited its phosphorylation in the hippocampus of OXYS and Wistar rats. Importantly, rapamycin treatment caused a compensatory increase in levels of S6 and correspondingly levels of phospo-S6 in the frontal cortex, indicating that some downstream events were compensatory preserved, explaining the lack of toxicity. We conclude that rapamycin in low chronic doses can suppress brain aging.

  10. Pullout bond strength of fiber posts luted to different depths and submitted to artificial aging.

    Science.gov (United States)

    Macedo, V C; Souza, N A Y; Faria e Silva, A L; Cotes, C; da Silva, C; Martinelli, M; Kimpara, E T

    2013-01-01

    The extension of fiber post cementation often does not seem to influence the fracture resistance of restorations. This study evaluated the effects of cementation depths on the retention of fiber posts submitted to artificial aging. One hundred and sixty bovine incisors were selected to assess post retention. Following endodontic treatment, the canals were flared with diamonds burs. Postholes were prepared in lengths of 5 or 10 mm, after which fiber posts were relined with composite resin and luted with RelyX ARC or RelyX Unicem. The samples were then submitted to thermal and/or mechanical cycling before testing their pullout bond strengths. Absence of cycling was used as a control. The results of each cement were submitted to two-way and post hoc Tukey tests (α=0.05). Independent of the aging protocol, a depth of 10 mm showed higher pullout bond strength than did 5 mm, except for RelyX Unicem without cycling. For RelyX ARC, thermomechanical cycling resulted in lower values than in the absence of cycling. Mechanical cycling alone promoted the highest bond strength when the posts were luted with RelyX Unicem. The effect of artificial aging on the pullout bond strength is dependent on the type of material and the depth.

  11. Influence of the preparation design and artificial aging on the fracture resistance of monolithic zirconia crowns.

    Science.gov (United States)

    Mitov, Gergo; Anastassova-Yoshida, Yana; Nothdurft, Frank Phillip; von See, Constantin; Pospiech, Peter

    2016-02-01

    The aim of this study was to evaluate the fracture resistance and fracture behavior of monolithic zirconia crowns in accordance with the preparation design and aging simulation method. An upper first molar was prepared sequentially with three different preparation designs: shoulderless preparation, 0.4 mm chamfer and 0.8 mm chamfer preparation. For each preparation design, 30 monolithic zirconia crowns were fabricated. After cementation on Cr-Co alloy dies, the following artificial aging procedures were performed: (1) thermal cycling and mechanical loading (TCML): 5000 cycles of thermal cycling 5℃-55℃ and chewing simulation (1,200,000 cycles, 50 N); (2) Low Temperature Degradation simulation (LTD): autoclave treatment at 137℃, 2 bar for 3 hours and chewing simulation; and (3) no pre-treatment (control group). After artificial aging, the crowns were loaded until fracture. The mean values of fracture resistance varied between 3414 N (LTD; 0.8 mm chamfer preparation) and 5712 N (control group; shoulderless preparation). Two-way ANOVA analysis showed a significantly higher fracture loads for the shoulderless preparation, whereas no difference was found between the chamfer preparations. In contrast to TCML, after LTD simulation the fracture strength of monolithic zirconia crowns decreased significantly. The monolithic crowns tested in this study showed generally high fracture load values. Preparation design and LTD simulation had a significant influence on the fracture strength of monolithic zirconia crowns.

  12. Artificial Neural Network-Based Early-Age Concrete Strength Monitoring Using Dynamic Response Signals.

    Science.gov (United States)

    Kim, Junkyeong; Lee, Chaggil; Park, Seunghee

    2017-06-07

    Concrete is one of the most common materials used to construct a variety of civil infrastructures. However, since concrete might be susceptible to brittle fracture, it is essential to confirm the strength of concrete at the early-age stage of the curing process to prevent unexpected collapse. To address this issue, this study proposes a novel method to estimate the early-age strength of concrete, by integrating an artificial neural network algorithm with a dynamic response measurement of the concrete material. The dynamic response signals of the concrete, including both electromechanical impedances and guided ultrasonic waves, are obtained from an embedded piezoelectric sensor module. The cross-correlation coefficient of the electromechanical impedance signals and the amplitude of the guided ultrasonic wave signals are selected to quantify the variation in dynamic responses according to the strength of the concrete. Furthermore, an artificial neural network algorithm is used to verify a relationship between the variation in dynamic response signals and concrete strength. The results of an experimental study confirm that the proposed approach can be effectively applied to estimate the strength of concrete material from the early-age stage of the curing process.

  13. Effect of opacifiers and UV absorbers on pigmented maxillofacial silicone elastomer, part 2: mechanical properties after artificial aging.

    Science.gov (United States)

    Nguyen, Caroline Tram; Chambers, Mark S; Powers, John M; Kiat-Amnuay, Sudarat

    2013-06-01

    There are reports of dissatisfaction with color instability and reduced lifetime of extraoral maxillofacial prostheses. Previous studies showed that UV mineral-based light-protecting agent (LP) improved color stability of MDX4-4210/Type A silicone elastomer. However, effects of this agent and opacifiers on mechanical properties of the elastomer are unknown. The purpose of this study was to evaluate the effect of 2 commonly used opacifiers and LP, a new opacifier, when combined with pigments on the mechanical properties of MDX4-4210/Type A silicone elastomer before and after artificial aging. Two commonly used opacifiers, titanium white dry pigment (TW) and silicone intrinsic white (SW) and LP were each combined with MDX4-4210/type A. Artists' oil pigment was then combined with the LP and TW groups, and silicone intrinsic pigments were combined with the SW group with 5 colors (no pigment=control, red, yellow, blue, or a combination of the 3 pigments). Ten dumbbell-shaped and 10 trouser-shaped specimens of each opacifier + pigment mixture, plus a control group with no opacifier and no pigment, were made for a total of 320 specimens. Half of the specimens (n=5) were aged in a chamber at 450 kJ/m(2). Specimens were tested for hardness (ASTM D2240), tensile strength (ASTM D412), tear strength (ASTM D624), and percentage elongation in a universal testing machine. A 3-way ANOVA and the Fisher PLSD test were performed (α=.05) for each mechanical property. After accelerated aging, values of Shore A hardness were the lowest for LP with all 5 pigments and the control, followed by SW and TW (Paging, tear strength, tensile strength, and elongation decreased significantly (Partificial aging. SW and TW preserved the mechanical properties of silicone in this study. Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  14. The effect of artificial accelerated weathering on the mechanical properties of maxillofacial polymers PDMS and CPE.

    Science.gov (United States)

    Eleni, P N; Krokida, M K; Polyzois, G L

    2009-06-01

    The effect of UVA-UVB irradiation on the mechanical properties of three different industrial types of polydimethylsiloxane and chlorinated polyethylene samples, used in maxillofacial prostheses, was investigated in this study. Mechanical properties and thermal analysis are commonly used to determine the structural changes and mechanical strength. An aging chamber was used in order to simulate the solar radiation and assess natural aging. Compression and tensile tests were conducted on a Zwick testing machine. Durometer Shore A hardness measurements were carried out in a CV digital Shore A durometer according to ASTM D 2240. Glass transition temperature was evaluated with a differential scanning calorimeter. Simple mathematical models were developed to correlate the measured properties with irradiation time. The effect of UVA-UVB irradiation on compressive behavior affected model parameters. Significant deterioration seems to occur due to irradiation in samples.

  15. Accelerated thermal aging of rubber modified epoxy encapsulants

    International Nuclear Information System (INIS)

    Sayre, J.A.

    1979-01-01

    A program is outlined to enable prediction of physical properties of rubber modified epoxy encapsulants over the life time of the extended life neutron generators. Preliminary results show that the chief aging phenomenon occurring is increased crosslink density of the epoxy matrix. No changes in the rubber phase have been detected. The effect of increased epoxy crosslink density has been higher volume resistivity at 66 0 C, increased tensile strength, and decreased ultimate elongation

  16. Accelerators

    CERN Multimedia

    CERN. Geneva

    2001-01-01

    The talk summarizes the principles of particle acceleration and addresses problems related to storage rings like LEP and LHC. Special emphasis will be given to orbit stability, long term stability of the particle motion, collective effects and synchrotron radiation.

  17. Accelerated aging in ultrathin films of a molecular glass former.

    Science.gov (United States)

    Sepúlveda, A; Leon-Gutierrez, E; Gonzalez-Silveira, M; Rodríguez-Tinoco, C; Clavaguera-Mora, M T; Rodríguez-Viejo, J

    2011-07-08

    We report the thermodynamic measurement of the enthalpy released during the aging of supported films of a molecular glass former, toluene, at temperatures well below the glass transition temperature. By using microfabricated devices with very short equilibration times (below 1 s), we evidence a remarkable variation of the relaxation rate on decreasing film thickness from 100 nm down to a 7 nm thick film. Our results demonstrate that surface atoms are more efficient than bulk atoms in attaining low energy configurations within the potential energy landscape.

  18. Artificial Neural Networks and Gene Expression Programing based age estimation using facial features

    Directory of Open Access Journals (Sweden)

    Baddrud Z. Laskar

    2015-10-01

    Full Text Available This work is about estimating human age automatically through analysis of facial images. It has got a lot of real-world applications. Due to prompt advances in the fields of machine vision, facial image processing, and computer graphics, automatic age estimation via faces in computer is one of the dominant topics these days. This is due to widespread real-world applications, in areas of biometrics, security, surveillance, control, forensic art, entertainment, online customer management and support, along with cosmetology. As it is difficult to estimate the exact age, this system is to estimate a certain range of ages. Four sets of classifications have been used to differentiate a person’s data into one of the different age groups. The uniqueness about this study is the usage of two technologies i.e., Artificial Neural Networks (ANN and Gene Expression Programing (GEP to estimate the age and then compare the results. New methodologies like Gene Expression Programing (GEP have been explored here and significant results were found. The dataset has been developed to provide more efficient results by superior preprocessing methods. This proposed approach has been developed, tested and trained using both the methods. A public data set was used to test the system, FG-NET. The quality of the proposed system for age estimation using facial features is shown by broad experiments on the available database of FG-NET.

  19. Protective role of female gender in programmed accelerated renal aging in the rat

    NARCIS (Netherlands)

    Pijacka, Wioletta; Clifford, Bethan; Tilburgs, Chantal; Joles, Jaap A.; Langley-Evans, Simon; McMullen, Sarah

    The aging kidney exhibits a progressive decline in glomerular filtration rate, accompanied by inflammatory and oxidative damage. We hypothesized that accelerated, age-related progression of renal injury is ovarian hormones-dependant. To address this we used an established model of developmentally

  20. Assessing degradation of composite resin cements during artificial aging by Martens hardness.

    Science.gov (United States)

    Bürgin, Stefan; Rohr, Nadja; Fischer, Jens

    2017-05-19

    Aim of the study was to verify the efficiency of Martens hardness measurements in detecting the degradation of composite resin cements during artificial aging. Four cements were used: Variolink II (VL2), RelyX Unicem 2 Automix (RUN), PermaFlo DC (PDC), and DuoCem (DCM). Specimens for Martens hardness measurements were light-cured and stored in water at 37 °C for 1 day to allow complete polymerization (baseline). Subsequently the specimens were artificially aged by water storage at 37 °C or thermal cycling (n = 6). Hardness was measured at baseline as well as after 1, 4, 9 and 16 days of aging. Specimens for indirect tensile strength measurements were produced in a similar manner. Indirect tensile strength was measured at baseline and after 16 days of aging (n = 10). The results were statistically analyzed using one-way ANOVA (α = 0.05). After water storage for 16 days hardness was significantly reduced for VL2, RUN and DCM while hardness of PDC as well as indirect tensile strength of all cements were not significantly affected. Thermal cycling significantly reduced both, hardness and indirect tensile strength for all cements. No general correlation was found between Martens hardness and indirect tensile strength. However, when each material was analyzed separately, relative change of hardness and of indirect tensile strength revealed a strong linear correlation. Martens hardness is a sensible test method to assess aging of resin composite cements during thermal cycling that is easy to perform.

  1. Acceleration of the ageing process by ionizing radiation. 2

    International Nuclear Information System (INIS)

    Rose, H.

    1976-01-01

    Transplants of spleen and kidney show changes in cell morphology with increasing age of the donor animals. In the group of juvenile donors the cell population emigrating from the spleen culture mainly consists of polymorphonuclear leukocytes. In the group of adult animals there are a few polymorphonuclear and many mononuclear cells. From spleen transplants of old donor animals large mononuclear cells with vacuolated cytoplasm and pyknotic and excentrically located nucleus are emigrating. Following whole-body X-irradiation of juvenile donor animals cells emigrate from tissue cultures depending on irradiation dose and time after irradiation. They show a morphology similar to that of non-irradiated old donors. Also in cultures of explants of adrenal cortex it was observed that X-irradiation of juvenile donor animals causes the migration of cells from the explants with a morphology which is typical of non-irradiated old donor animals. (author)

  2. Acceleration of ageing processes by ionizing radiation. 3

    International Nuclear Information System (INIS)

    Rose, H.

    1976-01-01

    The behaviour of renal cells of young, old and irradiated young rats has been studied in cell cultures. There are differences between young and old donors in the cell counts obtained after trypsinization of equal amounts of renal tissue as well as in the behaviour of the cells in cell cultures. The intercellular substance in the kidney increases with increasing age and cellular output becomes smaller. Whereas cells of young donors grew in the culture and formed a monolayer cellular lawn after 14 days, cell cultures of old donors grew very sparsely and degenerated early. After irradiation of young donors with 600 R we found the following results depending on the time following irradiation: If the animals were killed immediately after irradiation neither the cellular output after trypsinization nor the behaviour of the cells in culture differed from those of non-irradiated young controls. With regard to the criteria studied cells obtained 7 days after irradiation resembled those of old donors. (author)

  3. The Influence of Irradiation and Accelerated Aging on the Mechanical and Tribological Properties of the Graphene Oxide/Ultra-High-Molecular-Weight Polyethylene Nanocomposites

    Directory of Open Access Journals (Sweden)

    Guodong Huang

    2016-01-01

    Full Text Available Graphene oxide/ultra-high-molecular-weight polyethylene (GO/UHMWPE nanocomposite is a potential and promising candidate for artificial joint applications. However, after irradiation and accelerated aging, the mechanical and tribological behaviors of the nanocomposites are still unclear and require further investigation. GO/UHMWPE nanocomposites were successfully fabricated using ultrasonication dispersion, ball-milling, and hot-pressing process. Then, the nanocomposites were irradiated by gamma ray at doses of 100 kGy. Finally, GO/UHMWPE nanocomposites underwent accelerated aging at 80°C for 21 days in air. The mechanical and tribological properties of GO/UHMWPE nanocomposites have been evaluated after irradiation and accelerated aging. The results indicated that the incorporation of GO could enhance the mechanical, wear, and antiscratch properties of UHMWPE. After irradiation, these properties could be further enhanced, compared to unirradiated ones. After accelerated aging, however, these properties have been significantly reduced when compared to unirradiated ones. Moreover, GO and irradiation can synergistically enhance these properties.

  4. Accelerated aging effects on surface hardness and roughness of lingual retainer adhesives.

    Science.gov (United States)

    Ramoglu, Sabri Ilhan; Usumez, Serdar; Buyukyilmaz, Tamer

    2008-01-01

    To test the null hypothesis that accelerated aging has no effect on the surface microhardness and roughness of two light-cured lingual retainer adhesives. Ten samples of light-cured materials, Transbond Lingual Retainer (3M Unitek) and Light Cure Retainer (Reliance) were cured with a halogen light for 40 seconds. Vickers hardness and surface roughness were measured before and after accelerated aging of 300 hours in a weathering tester. Differences between mean values were analyzed for statistical significance using a t-test. The level of statistical significance was set at P statistically significant (P statistically significant (P .05). Accelerated aging significantly increased the surface microhardness of both light-cured retainer adhesives tested. It also significantly increased the surface roughness of the Transbond Lingual Retainer.

  5. Mechanical stiffness of TMJ condylar cartilage increases after artificial aging by ribose.

    Science.gov (United States)

    Mirahmadi, Fereshteh; Koolstra, Jan Harm; Lobbezoo, Frank; van Lenthe, G Harry; Ghazanfari, Samaneh; Snabel, Jessica; Stoop, Reinout; Everts, Vincent

    2018-03-01

    Aging is accompanied by a series of changes in mature tissues that influence their properties and functions. Collagen, as one of the main extracellular components of cartilage, becomes highly crosslinked during aging. In this study, the aim was to examine whether a correlation exists between collagen crosslinking induced by artificial aging and mechanical properties of the temporomandibular joint (TMJ) condyle. To evaluate this hypothesis, collagen crosslinks were induced using ribose incubation. Porcine TMJ condyles were incubated for 7 days with different concentrations of ribose. The compressive modulus and stiffness ratio (incubated versus control) was determined after loading. Glycosaminoglycan and collagen content, and the number of crosslinks were analyzed. Tissue structure was visualized by microscopy using different staining methods. Concomitant with an increasing concentration of ribose, an increase of collagen crosslinks was found. The number of crosslinks increased almost 50 fold after incubation with the highest concentration of ribose. Simultaneously, the stiffness ratio of the samples showed a significant increase after incubation with the ribose. Pearson correlation analyses showed a significant positive correlation between the overall stiffness ratio and the crosslink level; the higher the number of crosslinks the higher the stiffness. The present model, in which ribose was used to mimic certain aspects of age-related changes, can be employed as an in vitro model to study age-related mechanical changes in the TMJ condyle. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Consideration on A.C. electric motor subjected to thermal and radiation accelerated ageing

    International Nuclear Information System (INIS)

    Doina, Segarceanu; Geambau, C.

    2001-01-01

    In the containment building of a nuclear reactor there are many types of equipment, such as motors, valve and transducers. Electric motors used in nuclear power stations operate under specific environmental conditions. These conditions are determinate by temperature, humidity, pressure, radiation and they may be normal conditions in service, or may be accident conditions occur during the postulated LOCA event. The testing of electric motors capability to meet and exceed the required performances under specific operating environmental conditions all along its operating life implies the performing of a sequence of tests in which the environmental conditions are simulated in a accelerated manner followed by accident simulation tests. Simulating the ageing position of the test sequence is more difficult because of the problem of extrapolating the results of short term accelerated laboratory experiments to the long term exposure (up to 30 years) that actually occur in a nuclear plant. Thermally induced ageing is the most frequently used ageing stress and also the most easily. The insulated system of a motor ageing under the influence of temperature and high - energy radiation can suffer important changes in its electro-insulating properties. Thus, by way of accelerated ageing motors are brought under conditions equivalent to those at the end of their service life, in a relatively short time. Accelerated ageing enables a shorting of electric motor performance evaluation time. (author)

  7. Subjective and objective perceptions of specular gloss and surface roughness of esthetic resin composites before and after artificial aging.

    Science.gov (United States)

    Barucci-Pfister, Nadine; Göhring, Till N

    2009-04-01

    To correlate measurements of specular gloss and surface roughness of resin composite materials with subjective perception of luster before and after artificial aging. Polished specimens of eight composites were compared with human enamel (HE): microfilled SR Adoro (SR); microhybrid Artemis (AR), Enamel HFO (EHFO), Miris (MI), Tetric Ceram (TC), Venus (VE); and nanohybrid CeramX (CX) and nanofilled Filtek Supreme (FS). Before, during and after artificial aging (6000 thermal changes between 5 degrees C and 50 degrees C in an artificial oral environment, 240 hours storage in a container with ethanol, 300 minutes of toothbrushing), specular gloss and surface roughness were measured. Initial and endpoint gloss results were correlated with subjective luster rankings of 10 individuals. Artificial aging resulted in minor (EHFO, CX, FS), moderate (SR, MI, TC, VE) to high (AR) increases in surface roughness. Specular gloss decreased linearly for SR and FS, but decreased after an initial increase for all other materials. Subjectively, AR and FS were rated more and TC, VE and CX less lustrous than HE at baseline. After aging, luster of EHFO and FS was ranked higher and AR, TC, and VE lower than HE. Surface roughness was consistent with subjective perceptions (correlation coefficient: initial r = 0.913; endpoint r = 0.944, P artificial aging (initial r = 0.616, P = 0.1084; endpoint r = 0.834, P = 0.0072).

  8. Identification of Age, Temperature and Radiation Effect on Ferritic Steel Microstructure Based on Artificial Intelligence

    International Nuclear Information System (INIS)

    Mike Susmikanti; Entin Hartini; Antonius Sitompul

    2008-01-01

    In the construction of nuclear installation, it is important to know the material condition used on it. Considering mechanical properties of these materials, there are some material change affected by ageing, temperature and radiation. For some years, austenitic stainless steel are used as a fuel cladding in fast breeder reactor. However this material will not sufficiently competitive from economic point of view for the next year. Experiment result on ferritic steel gave information of stronger structural properties compared to austenitic stainless steel. Modeling and simulation will support further identification of this material changing caused by such effects. Pattern recognition of these changes base on artificial intelligence is expected to support the research and development activities on nuclear structure materials. Material structure pattern of these materials, observed by SEM, are converted using image processing system. Its characteristic is then analyzed with principal component using perception method, which usually used on identifying and learning neural network system based on artificial intelligence. Specific design and input are needed to identify the change of material structure pattern before and after any applied effect. In this paper, simulation of changing identification on three types ferritic steel F17(17 Cr), EM 12 (9 CR-2 MoNbV), and EMI 0 (9 Cr-I Mo) were done. The microstructure data before and after effect are taken from some references. The whole pattern recognition process are done using MATLAB software package. (author)

  9. [PSYCHO PHYSIOLOGICAL MARKERS OF ACCELERATED AGING AMONG THOSE WORKING WITH OCCUPATIONAL HAZARDS].

    Science.gov (United States)

    Bashkireva, A S; Kachan, Ye Yu; Kulapina, M E

    2015-01-01

    We assessed the significance of psycho physiological markers of accelerated aging of the function of attention using comparative analysis of two occupational groups in order to reveal how the working process affects mental work capacity. We revealed peculiarities of systemic structure of functions which determine mental work capacity depending on the age and length of service in lorry drivers. It was proved that decrease in the mnestic functions of lorry-drivers takes place 10-15 years earlier compared to the control group. Psycho physiological indices, reflecting the functioning of attention, decreased not only with aging but also with longer driving experience. Our results show that it is necessary to conduct further studies of psycho physiological markers of age-related decrease in short-term memory depending on the activities at work in order to prevent accelerated aging and achieve professional longevity.

  10. Brain-Derived Neurotrophic Factor Expression in Individuals With Schizophrenia and Healthy Aging: Testing the Accelerated Aging Hypothesis of Schizophrenia.

    Science.gov (United States)

    Islam, Farhana; Mulsant, Benoit H; Voineskos, Aristotle N; Rajji, Tarek K

    2017-07-01

    Schizophrenia has been hypothesized to be a syndrome of accelerated aging. Brain plasticity is vulnerable to the normal aging process and affected in schizophrenia: brain-derived neurotrophic factor (BDNF) is an important neuroplasticity molecule. The present review explores the accelerated aging hypothesis of schizophrenia by comparing changes in BDNF expression in schizophrenia with aging-associated changes. Individuals with schizophrenia show patterns of increased overall mortality, metabolic abnormalities, and cognitive decline normally observed later in life in the healthy population. An overall decrease is observed in BDNF expression in schizophrenia compared to healthy controls and in older individuals compared to a younger cohort. There is a marked decrease in BDNF levels in the frontal regions and in the periphery among older individuals and those with schizophrenia; however, data for BDNF expression in the occipital, parietal, and temporal cortices and the hippocampus is inconclusive. Accelerated aging hypothesis is supported based on frontal regions and peripheral studies; however, further studies are needed in other brain regions.

  11. Accelerated ageing and renal dysfunction links lower socioeconomic status and dietary phosphate intake.

    Science.gov (United States)

    McClelland, Ruth; Christensen, Kelly; Mohammed, Suhaib; McGuinness, Dagmara; Cooney, Josephine; Bakshi, Andisheh; Demou, Evangelia; MacDonald, Ewan; Caslake, Muriel; Stenvinkel, Peter; Shiels, Paul G

    2016-05-01

    We have sought to explore the impact of dietary Pi intake on human age related health in the pSoBid cohort (n=666) to explain the disparity between health and deprivation status in this cohort. As hyperphosphataemia is a driver of accelerated ageing in rodent models of progeria we tested whether variation in Pi levels in man associate with measures of biological ageing and health. We observed significant relationships between serum Pi levels and markers of biological age (telomere length (p=0.040) and DNA methylation content (p=0.028), gender and chronological age (p=0.032). When analyses were adjusted for socio-economic status and nutritional factors, associations were observed between accelerated biological ageing (telomere length, genomic methylation content) and dietary derived Pi levels among the most deprived males, directly related to the frequency of red meat consumption. Accelerated ageing is associated with high serum Pi levels and frequency of red meat consumption. Our data provide evidence for a mechanistic link between high intake of Pi and age-related morbidities tied to socio-economic status.

  12. Protective role of female gender in programmed accelerated renal aging in the rat.

    Science.gov (United States)

    Pijacka, Wioletta; Clifford, Bethan; Tilburgs, Chantal; Joles, Jaap A; Langley-Evans, Simon; McMullen, Sarah

    2015-04-01

    The aging kidney exhibits a progressive decline in glomerular filtration rate, accompanied by inflammatory and oxidative damage. We hypothesized that accelerated, age-related progression of renal injury is ovarian hormones-dependant. To address this we used an established model of developmentally programmed accelerated renal aging in the rat, superimposed by ovariectomy to assess interactions between ovarian hormones and the aging process. Under our experimental conditions, we found that kidney function worsens with age, that is GFR reduces over 18 month analyzed time-course and this was worsened by fetal exposure to maternal low-protein diet and absence of estrogen. Reduction in GFR was followed by increases in albuminuria, proteinuria, inflammatory markers, and tissue carbonyls, all suggesting inflammatory response and oxidative stress. This was associated with changes in AGTR2 expression which was greater at 18 months of age compared to earlier time points, but in MLP offspring only. Our studies show an influence of ovarian hormones on programmed accelerated renal aging and the AGTR2 across the lifespan. The main findings are that ovariectomy is a risk factor for increased aging-related renal injury and that this and oxidative damage might be related to changes in AGTR2 expression. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

  13. Influence of prior natural aging on the subsequent artificial aging response of aluminium alloy A356 with respective globular and dendritic microstructures

    CSIR Research Space (South Africa)

    Moller, H

    2011-01-01

    Full Text Available on the subsequent artificial aging response of SSM-HPDC A356 [9, 10]. An artificial aging treatment at 180◦C for 4 h can, however, negate the effects of any prior natural aging [10]. A recent review paper [15] on the heat treatment of Al- Si-Cu-Mg alloys (which..., 8]. The assumption is that these heat treatments are not necessarily the optimum treatments, as the difference in solidification history and microstructure of SSM processed components should be considered [7–11]. However, a recent paper...

  14. A systematic approach to standardize artificial aging of resin composite cements.

    Science.gov (United States)

    Blumer, Lukas; Schmidli, Fredy; Weiger, Roland; Fischer, Jens

    2015-07-01

    The aim of the investigation was to contribute to the ongoing discussion at the international standardization committee on how to artificially age dental resin composite cements. Indirect tensile strength (n=30) of a dual-cured resin composite cement (Panavia F2.0) was measured to evaluate the effect of water storage at 37°C or thermal cycling (5°C/55°C/1min) for up to 64 days. The influence of water temperature (5-65°C) after 16 days and the effect of 1 day water storage at 37°C prior to aging were assessed. Storage in air at 37°C served as control. Thermal cycling affected the indirect tensile strength most, followed by water storage at 55°C, whereas water storage at 37°C had only little influence. Major deterioration occurred before day 4 (≈6000 cycles). A 1-day pre-treatment by water storage at 37°C prior to thermal cycling attenuated the effect of aging. For the material investigated, thermal cycling for 4 days is the most efficient aging procedure. A 1-day water storage at 37°C prior to thermal cycling is recommended to allow complete polymerization. A 4-day water storage at 55°C may be considered as a viable alternative to thermal cycling. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  15. Comparative study of modified polypropylene nanocomposites under environment and accelerated ageing conditions

    International Nuclear Information System (INIS)

    Komatsu, Luiz Gustavo Hiroki

    2016-01-01

    The understanding of degradation mechanism action on the polymer nanocomposites in face of weathering (UV light, heat, acid rain, among others), is the key for development of new additives and new applications. In this work the nanocomposite synthesis was carried in molten state, using twin-screw extruder. The polymer matrix was the HMS-PP (high melt polypropylene) synthesized by gamma irradiation and the nanometric inorganic component was the montmorillonite clay. For better compatibilization between the matrix and clay, it were used maleic anhydride as coupling agent. For environment and in oven accelerated aging assays, the dumbbell samples were prepared under hot pressing. The characterization of clay addition effects and aging effects on the nanocomposites, required the use of techniques of Differential Scanning Calorimetry (DSC), Thermogravimetry (TGA), Fourier Transformed Infrared Spectroscopy (FT-IR), Xray Fluorescence (WDXRF), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and mechanical properties. Samples with 0.1; 1; 3; 5; 10 % of clay were tested. The sample with 5% of clay showed better stability on the environmental assay and accelerated aging in oven assay. On the other hand, the sample with higher percent of clay (10%), was more degraded under on environmental aging than under accelerated aging in stove. In this case, became more resistant until 56 days of assay. On the studied concentrations (less than ≤ 3%) of clay, it can be seen an equilibrium between barrier effect and metallic ions action accelerating the degradative process. (author)

  16. Long-Term Flexural Behaviors of GFRP Reinforced Concrete Beams Exposed to Accelerated Aging Exposure Conditions

    Directory of Open Access Journals (Sweden)

    Yeonho Park

    2014-06-01

    Full Text Available This study investigates the impact of accelerated aging conditions on the long-term flexural behavior and ductility of reinforced concrete (RC members with glass fiber-reinforced polymer (GFRP bars (RC-GFRP specimen and steel bars (RC-steel specimen. A total of thirty six specimens were designed with different amounts of reinforcement with three types of reinforcing bars (i.e., helically wrapped GFRP, sand-coated surface GFRP and steel. Eighteen specimens were subjected to sustained loads and accelerated aging conditions (i.e., 47 °C and 80% relative humidity in a chamber. The flexural behavior of specimens under 300-day exposure was compared to that of the companion specimens without experiencing accelerated aging conditions. Results indicate that the accelerated aging conditions reduced flexural capacity in not only RC-steel, but also RC-GFRP specimens, with different rates of reduction. Different types of GFRP reinforcement exhibited different rates of degradation of the flexural capacity when embedded in concrete under the same exposure conditions. Several existing models were compared with experimental results for predicting the deflection and deformability index for specimens. Bischoff and Gross’s model exhibited an excellent prediction of the time-dependent deflections. Except for the deformability index proposed by Jaeger, there was no general trend related to the aging duration. This study recommends the need for further investigation on the prediction of the deformability index.

  17. Effect of artificial aging on the bond durability of fissure sealants.

    Science.gov (United States)

    Yun, Xiaofei; Li, Wei; Ling, Chen; Fok, Alex

    2013-06-01

    To evaluate the effect of artificial aging on the bond durability of fissure sealants in vitro. Twenty bovine incisors received 4 different sealant treatments and were divided into four groups: 1. Ultraseal XT plus (UX); 2. Enamel Loc (EL); 3. 35% phosphoric acid plus Enamel Loc (PEL); 4. Adper Prompt L-Pop plus Clinpro (PPC). Beam-shaped specimens were prepared and randomly divided into three subgroups. One subgroup underwent the microtensile bond strength (µTBS) test after 24-h storage in 37°C water. The other two subgroups were also subjected to the microtensile bond strength test after 5000 and 10,000 thermal cycles, respectively. Another twelve intact human third molars were sealed using 1 of 3 methods and were divided into 3 groups of 4 each: 1. Ultraseal XT plus; 2. Adper Prompt L-Pop plus Clinpro; and 3. Enamel Loc. Two specimens from each group were immersed in a 50% silver nitrate solution for 24 h, followed by exposure to fluorescent light for 8 h, before being scanned in a micro-CT (microcomputer tomography) machine. The other two were handled in the same way after undergoing 10,000 thermal cycles. The CT images obtained were evaluated. All samples from the EL group were broken during preparation, so no µTBS results were available. After 5000 thermal cycles, the bond strengths of the three other groups (UX, PEL, PPC) decreased significantly (p artificial aging. Micro-CT, a nondestructive analytical tool, may be used to evaluate the sealant/enamel interface effectively.

  18. Seismic-fragility tests of new and accelerated-aged Class 1E battery cells

    International Nuclear Information System (INIS)

    Bonzon, L.L.; Janis, W.J.; Black, D.A.; Paulsen, G.A.

    1987-01-01

    The seismic-fragility response of naturally-aged nuclear station safety-related batteries is of interest for two reasons: (1) to determine actual failure modes and thresholds and (2) to determine the validity of using the electrical capacity of individual cells as an indicator of the potential survivability of a battery given a seismic event. Prior reports in this series discussed the seismic-fragility tests and results for three specific naturally-aged cell types: 12-year old NCX-2250, 10-year old LCU-13, and 10-year old FHC-19. This report focuses on the complementary approach, namely, the seismic-fragility response of accelerated-aged batteries. Of particular interest is the degree to which such approaches accurately reproduce the actual failure modes and thresholds. In these tests the significant aging effects observed, in terms of seismic survivability, were: embrittlement of cell cases, positive bus material and positive plate grids; and excessive sulphation of positive plate active material causing hardening and expansion of positive plates. The IEEE Standard 535 accelerated aging method successfully reproduced seismically significant aging effects in new cells but accelerated grid embrittlement an estimated five years beyond the conditional age of other components

  19. Formation and reversion of clusters during natural aging and subsequent artificial aging in an Al–Mg–Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Aruga, Yasuhiro, E-mail: aruga.yasuhiro@kobelco.com [Materials Research Laboratory, Kobe Steel, Ltd., 1-5-5 Takatsukadai, Nishi-ku, Kobe 651-2271 (Japan); Kozuka, Masaya, E-mail: kozuka.masaya@kobelco.com [Materials Research Laboratory, Kobe Steel, Ltd., 1-5-5 Takatsukadai, Nishi-ku, Kobe 651-2271 (Japan); Takaki, Yasuo, E-mail: takaki.yasuo@kobelco.com [Aluminum Sheets and Coils Research Department, Aluminum & Copper Business, Kobe Steel, Ltd., 15 Kinugaoka, Moka, Tochigi 321-4367 (Japan); Sato, Tatsuo, E-mail: sato.t.ap@m.titech.ac.jp [Precision and Intelligence Laboratory, Tokyo Institute of Technology, Nagatsuta 4259-R2-18, Midori-ku, Yokohama 226-8503 (Japan)

    2015-04-17

    The continuous changes in number density, size distribution and chemical composition of clusters during natural aging (NA), and subsequent artificial aging (AA) at 443 K, in an Al–0.62Mg–0.93Si (mass%) alloy have been evaluated using atom probe tomography. The data show almost no change in the average size and Mg/Si ratio (at% ratio) of clusters during NA. The highest hardness and most-dense clusters, following NA, and the largest drop in hardness, during AA for 1.2 ks, are observed in the material with the longest NA period. In contrast with the published literature, which suggests that only small clusters revert into solution, the number density of clusters decreased, with no dependence on the cluster size, during AA for 1.2 ks, resulting in a slight decrease in the average radius of clusters. Things to be emphasized are that the number density of clusters with the Mg/Si ratio below 0.4 stays pretty much the same during AA, whereas other clusters decrease during the first 1.2 ks and then increase again during the prolonged AA for up to 3.6 ks. This work is the first to reveal that the typical Si-rich clusters can neither be dissolved nor grow further, although the size is small. In other words, it is believed that the typical Si-rich clusters can lead to the retardation of the hardness increase during AA called as negative effect of NA.

  20. Formation and reversion of clusters during natural aging and subsequent artificial aging in an Al–Mg–Si alloy

    International Nuclear Information System (INIS)

    Aruga, Yasuhiro; Kozuka, Masaya; Takaki, Yasuo; Sato, Tatsuo

    2015-01-01

    The continuous changes in number density, size distribution and chemical composition of clusters during natural aging (NA), and subsequent artificial aging (AA) at 443 K, in an Al–0.62Mg–0.93Si (mass%) alloy have been evaluated using atom probe tomography. The data show almost no change in the average size and Mg/Si ratio (at% ratio) of clusters during NA. The highest hardness and most-dense clusters, following NA, and the largest drop in hardness, during AA for 1.2 ks, are observed in the material with the longest NA period. In contrast with the published literature, which suggests that only small clusters revert into solution, the number density of clusters decreased, with no dependence on the cluster size, during AA for 1.2 ks, resulting in a slight decrease in the average radius of clusters. Things to be emphasized are that the number density of clusters with the Mg/Si ratio below 0.4 stays pretty much the same during AA, whereas other clusters decrease during the first 1.2 ks and then increase again during the prolonged AA for up to 3.6 ks. This work is the first to reveal that the typical Si-rich clusters can neither be dissolved nor grow further, although the size is small. In other words, it is believed that the typical Si-rich clusters can lead to the retardation of the hardness increase during AA called as negative effect of NA

  1. Influence of Photoinitiator on Accelerated Artificial Aging and Bond Strength of Experimental Resin Cements.

    Science.gov (United States)

    Righi, Helouise; Costa, Ana Rosa; Oliveira, Dayane Carvalho Ramos Salles de; Abuna, Gabriel Flores; Sinhoreti, Mario Alexandre Coelho; Naufel, Fabiana Scarparo

    2018-01-01

    The goal of this study was to evaluate in vitro the effect of the photoinitiator phenylpropanedione (PPD), alone or combined with camphorquinone (CQ), on color stability of photoactivated resin cements and their bond strength to ceramics using a micro-shear test. Four resin cements were used: a commercial brand cement (RelyX Veneer®) and 3 experimental cements with different types and concentration of photoinitiators. For color analysis, ceramic discs were cemented on bovine dentin specimens to simulate indirect restorations (n=8) and were exposed to UV for 120 h and tested for color alteration using a reflectance spectrophotometer and the CIEL*a*b* system. Data were analyzed by Anova and Tukey's test at 5% significance level. The color test results did not present statistically significant difference for the ∆E for all the studied cements, neither for ∆L, ∆a and ∆b. For the bond strength, all the studied cements showed statistically significant differences to each other, with the highest result for the RelyX Veneer® (29.07 MPa) cement, followed by the cement with CQ (21.74 MPa) and CQ+PPD (19.09 MPa) cement; the lowest result was obtained by the cement using only PPD as a photoinitiator (13.99 MPa). So, based on the studied parameters, PPD was not advantageous as photoinitiator of resin cements, because it showed a low value of bond strength to the ceramics and no superior color stability.

  2. Accelerator mass spectrometry radiocarbon ages of amino acid extracts from Californian palaeoindian skeletons

    International Nuclear Information System (INIS)

    Bada, J.L.; Gillespie, R.; Gowlett, J.A.J.; Hedges, R.E.M.

    1984-01-01

    The authors have used accelerator mass spectrometry to determine the radiocarbon ages of the amino acid extracts used in the original racemization studies of skeletal remains found in California. The studies indicate that some of the controversial Californian skeletons, which had been assigned to the Upper Pleistocene, are in fact Holocene. (author)

  3. Accelerated aging and discharge of lithium/thionyl-chloride D cells

    Science.gov (United States)

    Cieslak, W. R.

    Lithium/Thionyl-Chloride spiral wound 'D' cells from a variety of suppliers have been evaluated. Abuse testing has been used to verify safety of the cells, and accelerated aging has been used to estimate their performance for long life projects.

  4. Accelerated aging and discharge of lithium/thionyl-chloride D'' cells

    Energy Technology Data Exchange (ETDEWEB)

    Cieslak, W.R.

    1991-01-01

    Lithium/Thionyl-Chloride spiral wound D'' cells from a variety of suppliers have been evaluated. Abuse testing has been used to verify safety of the cells, and accelerated aging has been used to estimate their performance for long life projects. 2 tabs.

  5. Accelerated aging and controlled deterioration for the determination of the physiological potential of onion seeds

    Directory of Open Access Journals (Sweden)

    Rodo Angelica Brod

    2003-01-01

    Full Text Available International research on vegetable seed vigor is not at the same level attained for grain crops species. This study was conducted to identify reliable procedures for the accelerated aging and controlled deterioration tests to rank onion (Allium cepa L. seed lots according to their physiological potential. Six seed lots of the cultivars Aurora and Petroline were evaluated in the laboratory for germination, first count, seedling vigor classification, traditional and saturated salt accelerated aging (41masculineC / 48 and 72 h, controlled deterioration (24% of water / 45masculineC / 24 h and seedling emergence tests. Seed moisture content after the saturated salt accelerated aging test was lower and uniform, which is considered an important advantage in comparison to the traditional procedure. The saturated salt accelerated aging (41masculineC / 48 and 72 h and controlled deterioration (moisture content adjusted to 24% / 45masculineC / 24 h tests were the best procedures to assess the physiological potential of onion seeds, and are indicated for use in quality control programs.

  6. Effects of artificial aging conditions on yttria-stabilized zirconia implant abutments.

    Science.gov (United States)

    Basílio, Mariana de Almeida; Cardoso, Kátia Vieira; Antonio, Selma Gutierrez; Rizkalla, Amin Sami; Santos Junior, Gildo Coelho; Arioli Filho, João Neudenir

    2016-08-01

    Most ceramic abutments are fabricated from yttria-stabilized tetragonal zirconia (Y-TZP). However, Y-TZP undergoes hydrothermal degradation, a process that is not well understood. The purpose of this in vitro study was to assess the effects of artificial aging conditions on the fracture load, phase stability, and surface microstructure of a Y-TZP abutment. Thirty-two prefabricated Y-TZP abutments were screwed and tightened down to external hexagon implants and divided into 4 groups (n = 8): C, control; MC, mechanical cycling (1×10(6) cycles; 10 Hz); AUT, autoclaving (134°C; 5 hours; 0.2 MPa); and TC, thermal cycling (10(4) cycles; 5°/55°C). A single-load-to-fracture test was performed at a crosshead speed of 0.5 mm/min to assess the assembly's resistance to fracture (ISO Norm 14801). X-ray diffraction (XRD) analysis was applied to observe and quantify the tetragonal-monoclinic (t-m) phase transformation. Representative abutments were examined with high-resolution scanning electron microscopy (SEM) to observe the surface characteristics of the abutments. Load-to-fracture test results (N) were compared by ANOVA and Tukey test (α=.05). XRD measurements revealed the monoclinic phase in some abutments after each aging condition. All the aging conditions reduced the fracture load significantly (Paging conditions. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  7. Effect of artificial aging and surface treatment on bond strengths to dental zirconia.

    Science.gov (United States)

    Perdigão, J; Fernandes, S D; Pinto, A M; Oliveira, F A

    2013-01-01

    The objective of this project was to study the influence of artificial aging and surface treatment on the microtensile bond strengths (μTBS) between zirconia and a phosphate monomer-based self-adhesive cement. Thirty zirconia disks (IPS e.max ZirCAD, Ivoclar Vivadent) were randomly assigned to two aging regimens: AR, used as received, which served as a control, and AG, artificial aging to simulate low-temperature degradation. Subsequently, the disks of each aging regimen were assigned to three surface treatments: NT, no surface treatment; CO, surface silicatization with CoJet sand (3M ESPE); and ZP, zirconia surface treated with Z-Prime Plus (Bisco Inc). Thirty discs were made of Filtek Z250 (3M ESPE) composite resin and luted to the zirconia discs using RelyX Unicem (3M ESPE). The specimens were sectioned with a diamond blade in X and Y directions to obtain bonded beams with a cross-section of 1.0 ± 0.2 mm. The beams were tested in tensile mode in a universal testing machine at a speed of 0.5 mm/min to measure μTBS. Selected beams were selected for fractographic analysis under the SEM. Statistical analysis was carried out with two-way analysis of variance and Dunnett T3 post hoc test at a significance level of 95%. The mean μTBS for the three AR subgroups (AR-NT, AR-CO, and AR-ZP) were significantly higher than those of the corresponding AG groups (p<0.0001). Both AR-CO and AR-ZP resulted in statistically significant higher mean bond strengths than the group AR-NT (p<0.006 and p<0.0001, respectively). Both AG-CO and AG-ZP resulted in statistically significant higher mean bond strengths than the group AG-NT (both at p<0.0001). Overall, AG decreased mean μTBS. Under the SEM, mixed failures showed residual cement attached to the zirconia side of the beams. CO resulted in a characteristic roughness of the zirconia surface. AR-ZP was the only group for which the amount of residual cement occupied at least 50% of the interface in mixed failures.

  8. Does artificial aging affect mechanical properties of CAD/CAM composite materials.

    Science.gov (United States)

    Egilmez, Ferhan; Ergun, Gulfem; Cekic-Nagas, Isil; Vallittu, Pekka K; Lassila, Lippo V J

    2018-01-01

    The purpose of this study was to determine the flexural strength and Weibull characteristics of different CAD/CAM materials after different in vitro aging conditions. The specimens were randomly assigned to one of the six in vitro aging conditions: (1) water storage (37°C, 3 weeks), (2) boiling water (24h), (3) hydrochloric acid exposure (pH: 1.2, 24h), (4) autoclave treatment (134°C, 200kPa, 12h), (5) thermal cycling (5000 times, 5-55°C), (6) cyclic loading (100N, 50,000 cycles). No treatment was applied to the specimens in control group. Three-point bending test was used for the calculation of flexural strength. The reliability of the strength was assessed by Weibull distribution. Surface roughness and topography was examined by coherence scanning interferometry. Evaluated parameters were compared using the Kruskall-Wallis or Mann-Whitney U test. Water storage, autoclave treatment and thermal cycling significantly decreased the flexural strength of all materials (p0.05). Weibull moduli of Cerasmart™ and Lava™ Ultimate were similar with control. Vita Enamic ® exhibited similar Weibull moduli in all aging groups except the HCl treated group (p>0.05). R a values of Cerasmart™ and Lava™ Ultimate were in the range of 0.053-0.088μm in the aged groups. However R a results of Vita Enamic ® were larger than 0.2μm. Flexural strength of newly developed restorative CAD/CAM materials was significantly decreased by artificial aging. Cyclic loading or HCl exposure does not affect to the flexural strength and structural reliability of Cerasmart™ and Lava™ Ultimate. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  9. Deficiency in DNA damage response of enterocytes accelerates intestinal stem cell aging in Drosophila.

    Science.gov (United States)

    Park, Joung-Sun; Jeon, Ho-Jun; Pyo, Jung-Hoon; Kim, Young-Shin; Yoo, Mi-Ae

    2018-03-07

    Stem cell dysfunction is closely linked to tissue and organismal aging and age-related diseases, and heavily influenced by the niche cells' environment. The DNA damage response (DDR) is a key pathway for tissue degeneration and organismal aging; however, the precise protective role of DDR in stem cell/niche aging is unclear. The Drosophila midgut is an excellent model to study the biology of stem cell/niche aging because of its easy genetic manipulation and its short lifespan. Here, we showed that deficiency of DDR in Drosophila enterocytes (ECs) accelerates intestinal stem cell (ISC) aging. We generated flies with knockdown of Mre11 , Rad50 , Nbs1 , ATM , ATR , Chk1 , and Chk2 , which decrease the DDR system in ECs. EC-specific DDR depletion induced EC death, accelerated the aging of ISCs, as evidenced by ISC hyperproliferation, DNA damage accumulation, and increased centrosome amplification, and affected the adult fly's survival. Our data indicated a distinct effect of DDR depletion in stem or niche cells on tissue-resident stem cell proliferation. Our findings provide evidence of the essential role of DDR in protecting EC against ISC aging, thus providing a better understanding of the molecular mechanisms of stem cell/niche aging.

  10. Body Acceleration as Indicator for Walking Economy in an Ageing Population.

    Science.gov (United States)

    Valenti, Giulio; Bonomi, Alberto G; Westerterp, Klaas R

    2015-01-01

    In adults, walking economy declines with increasing age and negatively influences walking speed. This study aims at detecting determinants of walking economy from body acceleration during walking in an ageing population. 35 healthy elderly (18 males, age 51 to 83 y, BMI 25.5±2.4 kg/m2) walked on a treadmill. Energy expenditure was measured with indirect calorimetry while body acceleration was sampled at 60Hz with a tri-axial accelerometer (GT3X+, ActiGraph), positioned on the lower back. Walking economy was measured as lowest energy needed to displace one kilogram of body mass for one meter while walking (WCostmin, J/m/kg). Gait features were extracted from the acceleration signal and included in a model to predict WCostmin. On average WCostmin was 2.43±0.42 J/m/kg and correlated significantly with gait rate (r2 = 0.21, peconomy is induced by the adoption of an increased gait rate and by irregular body acceleration in the horizontal plane.

  11. Effect of accelerated aging on the microhardness and color stability of flexible resins for dentures

    Directory of Open Access Journals (Sweden)

    Marcelo Coelho Goiato

    2010-03-01

    Full Text Available Acrylic resins have been widely used due to their acceptable esthetics and desirable characteristics such as easy handling, good thermal conductivity, low permeability to oral fluids and color stability. Flexible resins were introduced on the market as an alternative to the use of conventional acrylic resins in the construction of complete and partial removable dentures. Although these resins present advantages in terms of esthetics and comfort, studies assessing chromatic and microhardness alterations of these materials are still scarce in the related literature. The aim of this study was to evaluate the chromatic and microhardness alterations of two commercial brands of flexible resins in comparison to the conventional resin Triplex when submitted to accelerated aging. The resins were manipulated according to manufacturers' instructions and inserted into a silicone matrix to obtain 21 specimens divided into 3 groups: Triplex, Ppflex and Valplast. Triplex presented the highest microhardness value (p < 0.05 for all the aging periods, which was significantly different from that of the other resins, followed by the values of Valplast and Ppflex. Comparison between the flexible resins (Ppflex and Valplast revealed a statistically significant difference (p < 0.05 as regards color. The flexible resin Ppflex and the conventional resin Triplex presented no statistically significant difference (p < 0.05 as regards aging. The accelerated aging significantly increased the microhardness values of the resins, with the highest values being observed for Triplex. Valplast presented the greatest chromatic alteration after accelerated aging.

  12. ACCELERATED AGING TEST IN DETERMINING THE VIGOUR OF SUNFLOWER SEEDS WITH AND WITHOUT PERICARP

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    K. R. Ducatti

    2014-09-01

    Full Text Available The standard germination test alone is insufficient to attest the quality of seeds, making necessary correlation’s with vigour tests, to determine more accurately the physiological potential of a seeds lot. The accelerated aging test is an option for determine the vigour and consists in submits seeds to high temperatures and humidity, for different periods of time, has not yet standardized. The objective of this work was to analyze the efficiency of the accelerated aging test in the assessment of the effect of a lot of sunflower seed, by three periods of aging (48, 56 and 72 hours in 42 °C temperature, in seeds with and without pericarp (manually removed and relate the results with electrical conductivity test and germination first count. The experimental design was a completely randomized design and the comparison of averages made using Tukey's test at 5% probability. The results showed that standard germination, electrical conductivity and germination first count, the seeds without pericarp showed better performance. In relation to the accelerated aging, only in the period of 72 hours of aging there was no significant difference between the treatments. In this way, the appropriate period to identify differences in force between the treatments was 72 hours, which showed a positive correlation with the germination first count and electrical conductivity.

  13. In vitro cytotoxicity of maxillofacial silicone elastomers: effect of accelerated aging.

    Science.gov (United States)

    Bal, Bilge Turhan; Yilmaz, Handan; Aydin, Cemal; Karakoca, Seçil; Yilmaz, Sükran

    2009-04-01

    The purpose of this in vitro study was to evaluate the cytotoxicity of three maxillofacial silicone elastomers at 24, 48, and 72 h on L-929 cells and to determine the effect of accelerated aging on the cytotoxicity of these silicone elastomers. Disc-shaped test samples of maxillofacial silicone elastomers (Cosmesil, Episil, Multisil) were fabricated according to manufacturers' instructions under aseptic conditions. Samples were then divided into three groups: (1) not aged; (2) aged for 150 h with an accelerated weathering tester; and (3) aged for 300 h. Then the samples were placed in Dulbecco's Modified Eagle Medium/Ham's F12 (DMEM/F12) for 24, 48, and 72 h. After the incubation periods, cytotoxicity of the extracts to cultured fibroblasts (L-929) was measured by MTT assay. The degree of cytotoxicity of each sample was determined according to the reference value represented by the cells with a control (culture without sample). Statistical significance was determined by repeated measurement ANOVA (p test (p test materials in each group demonstrated high survival rates in MTT assay (Episil; 93.84%, Multisil; 88.30%, Cosmesil; 87.50%, respectively); however, in all groups, Episil material demonstrated significantly higher cell survival rate after each of the experimental incubation periods (p Accelerated aging for 150 and 300 h had no significant effect on the biocompatibility of maxillofacial silicone elastomers tested (p > 0.05).

  14. Degradation of impact fracture during accelerated aging of weld metal on microalloyed steel

    International Nuclear Information System (INIS)

    Vargas-Arista, B.; Hallen, J. M.; Albiter, A.; Angeles-Chavez, C.

    2008-01-01

    The effect of accelerated aging on the toughness and fracture of the longitudinal weld metal on an API5L-X52 line pipe steel was evaluated by Charpy V-notch impact test, fracture analysis and transmission electron microscopy. Aging was performed at 250 degree centigrade for 100 to 1000 h. The impact results indicated a significant reduction in the fracture energy and impact toughness as a function of aging time, which were achieved by the scanning electron microscope fractography that showed a decrease in the vol fraction of microvoids by Charpy ductile failure with the aging time, which favored the brittle fracture by transgranular cleavage. The minimum vol fraction of microvoids was reached at 500 h due to the peak aged. The microstructural analysis indicated the precipitation of transgranular iron nano carbides in the aged specimens, which was related to the deterioration of toughness and change in the ductile to brittle behavior. (Author) 15 refs

  15. The role of oxidative and nitrosative stress in accelerated aging and major depressive disorder.

    Science.gov (United States)

    Maurya, Pawan Kumar; Noto, Cristiano; Rizzo, Lucas B; Rios, Adiel C; Nunes, Sandra O V; Barbosa, Décio Sabbatini; Sethi, Sumit; Zeni, Maiara; Mansur, Rodrigo B; Maes, Michael; Brietzke, Elisa

    2016-02-04

    Major depressive disorder (MDD) affects millions of individuals and is highly comorbid with many age associated diseases such as diabetes mellitus, immune-inflammatory dysregulation and cardiovascular diseases. Oxidative/nitrosative stress plays a fundamental role in aging, as well as in the pathogenesis of neurodegenerative/neuropsychiatric disorders including MDD. In this review, we critically review the evidence for an involvement of oxidative/nitrosative stress in acceleration of aging process in MDD. There are evidence of the association between MDD and changes in molecular mechanisms involved in aging. There is a significant association between telomere length, enzymatic antioxidant activities (SOD, CAT, GPx), glutathione (GSH), lipid peroxidation (MDA), nuclear factor κB, inflammatory cytokines with MDD. Major depression also is characterized by significantly lower concentration of antioxidants (zinc, coenzyme Q10, PON1). Since, aging and MDD share a common biological base in their pathophysiology, the potential therapeutic use of antioxidants and anti-aging molecules in MDD could be promising.

  16. Investigation of Ageing Behaviour of Nitrile-Butadiene Rubber with Added Graphene in an Accelerated Thermal Ageing Environment

    Directory of Open Access Journals (Sweden)

    Fei-Zhou Li

    2018-01-01

    Full Text Available In this paper, the thermal ageing of nitrile-butadiene rubber (NBR reinforced with different graphene (GE concentrations has been investigated. NBR and NBR-GE composites were exposed to an accelerated thermal ageing environment produced by an air-circulating oven for seven days. The mechanical properties, chemical changes, and thermal stability of ageing samples and neat samples were evaluated. The results showed that the surface damage of NBR was severe and inhomogeneous, and the degree of ageing was most serious on the edge region of the voids, but NBR-GE composites were changed slightly before and after ageing. The tensile strength increased with the increase of GE concentration, up to a maximum value, and decreased with further increases in GE concentration. The GE embedded crosslinked network limited the segment movement of chains in the stretch direction and played a role in the composites properties, and the GE sheets (contained the functional groups of −OH, −C=O and C=C after ageing. This behaviour may indicate greater interface adhesion between the GE and NBR. In addition, results obtained by thermogravimetric analysis (TGA indicated that the thermal stability of NBR significantly changed with accelerated thermal ageing environment, but with addition of a certain amount of GE to NBR, the thermal stability of NBR could be improved. The NBR/GE composites exhibited good comprehensive performance with a mass fraction of GE of 10 %. Before and after the thermal ageing, the failure mechanism of NBR-GE composites appeared intergranular and ductile fracture, respectively.

  17. Fracture resistance of zirconia-based implant abutments after artificial long-term aging.

    Science.gov (United States)

    Alsahhaf, Abdulaziz; Spies, Benedikt Christopher; Vach, Kirstin; Kohal, Ralf-Joachim

    2017-02-01

    To investigate the survival rate, fracture strength, bending moments, loading to fracture and fracture modes of different designs of zirconia abutments after dynamic loading with thermocycling, and compare these values to titanium abutments. A total of 80 abutment samples were divided into 5 test groups of 16 samples in each group. The study included the following groups, "Group 1" CAD/CAM produced all-zirconia abutments, "Group 2" titanium abutments, "Group 3" zirconia-abutments adhesively luted to a titanium base, "Group 4" prefabricated all-zirconia abutments and "Group 5" zirconia-abutments glass soldered to a titanium base. Half the number of samples in each group was exposed to 1.2 million loading cycles (5-years simulation) in the chewing simulator. The samples that survived the artificial aging were later tested for fracture strength in a universal testing machine. The remaining 8 samples of the group were directly tested for fracture strength. All samples exposed to the 5-years artificial aging survived except of six samples in one group (Group 1). The surviving samples were later fracture tested in the universal testing machine. The bending moments (Ncm) values were as follow: Exposed groups: "Group 1" 94.5Ncm; "Group 2" 599.2Ncm; "Group 3" 477.5Ncm; "Group 4" 314.4Ncm; "Group 5" 509.4Ncm. Non-exposed groups: "Group 1" 269.3Ncm; "Group 2" 474.2Ncm; "Group 3" 377.6Ncm; "Group 4" 265.4Ncm; "Group 5" 372.4Ncm. Except in Group 1, the values were higher in the exposed groups, although, statistically there was no difference (p>0.05). The one-piece ZrO2-abutment group (Group 1 and Group 4) exhibited lower values, while the two-piece ZrO2-abutment groups (Group 3 and Group 5) showed similar values and fracture modes like the titanium abutment group. The titanium abutment group showed the highest values of bending moments among all groups. The implant-abutment connection area appeared to influence the bending moment value and the fracture mode of the tested

  18. Obesity-induced oxidative stress, accelerated functional decline with age and increased mortality in mice.

    Science.gov (United States)

    Zhang, Yiqiang; Fischer, Kathleen E; Soto, Vanessa; Liu, Yuhong; Sosnowska, Danuta; Richardson, Arlan; Salmon, Adam B

    2015-06-15

    Obesity is a serious chronic disease that increases the risk of numerous co-morbidities including metabolic syndrome, cardiovascular disease and cancer as well as increases risk of mortality, leading some to suggest this condition represents accelerated aging. Obesity is associated with significant increases in oxidative stress in vivo and, despite the well-explored relationship between oxidative stress and aging, the role this plays in the increased mortality of obese subjects remains an unanswered question. Here, we addressed this by undertaking a comprehensive, longitudinal study of a group of high fat-fed obese mice and assessed both their changes in oxidative stress and in their performance in physiological assays known to decline with aging. In female C57BL/6J mice fed a high-fat diet starting in adulthood, mortality was significantly increased as was oxidative damage in vivo. High fat-feeding significantly accelerated the decline in performance in several assays, including activity, gait, and rotarod. However, we also found that obesity had little effect on other markers of function and actually improved performance in grip strength, a marker of muscular function. Together, this first comprehensive assessment of longitudinal, functional changes in high fat-fed mice suggests that obesity may induce segmental acceleration of some of the aging process. Published by Elsevier Inc.

  19. Evaluation of hardness and colour change of soft liners after accelerated ageing.

    Science.gov (United States)

    Mancuso, Daniela Nardi; Goiato, Marcelo Coelho; Zuccolotti, Bruna Carolina Rossatti; Moreno, Amália; dos Santos, Daniela Micheline

    2009-07-01

    Soft liners have been developed to offer comfort to denture wearers. However, this comfort is compromised when there is a change in the properties of the material, causing colour change, solubility, absorption and hardening. These characteristics can compromise the longevity of soft liners. The aim of this in vitro study was to investigate the effect of ageing on both the hardness and colour change of two soft liners following accelerated ageing. Two denture liners, one resin based (Trusoft, Bosworth, Illinois, USA) and one silicone based (Ufi Gel P, Voco GMBH, Cuxhaven, Germany), were tested in this study for both hardness (using the Shore A scale) and colour change (using the CIE L*a*b* colour scale), initially and after 1008 hours (6 weeks) of accelerated ageing. Statistical analysis was performed using the unpaired t-test with the Welch correction. These indicated that both materials increased in hardness and underwent colour change after accelerated ageing. The initial hardness of Trusoft was far lower than that of Ufi Gel P (18.2 Shore A units vs 34.8 Shore A units). However, for Trusoft the changes for both hardness (from 18.2 to 52.1 Shore A units) and colour change (16.85 on the CIE L*a*b* colour scale) were greater than those for Ufi Gel P, for which hardness changed from 34.8 to 36.5 Shore A units and the colour change was 5.19 on the CIE L*a*b* colour scale. Ufi Gel P underwent less hardness and colour change after accelerated ageing than Trusoft. On the other hand, the use of Trusoft may be preferable in cases where initial softness is a major consideration, such as when relining an immediate denture after implant surgery.

  20. Accelerated aging in schizophrenia patients: the potential role of oxidative stress.

    Science.gov (United States)

    Okusaga, Olaoluwa O

    2014-08-01

    Several lines of evidence suggest that schizophrenia, a severe mental illness characterized by delusions, hallucinations and thought disorder is associated with accelerated aging. The free radical (oxidative stress) theory of aging assumes that aging occurs as a result of damage to cell constituents and connective tissues by free radicals arising from oxygen-associated reactions. Schizophrenia has been associated with oxidative stress and chronic inflammation, both of which also appear to reciprocally induce each other in a positive feedback manner. The buildup of damaged macromolecules due to increased oxidative stress and failure of protein repair and maintenance systems is an indicator of aging both at the cellular and organismal level. When compared with age-matched healthy controls, schizophrenia patients have higher levels of markers of oxidative cellular damage such as protein carbonyls, products of lipid peroxidation and DNA hydroxylation. Potential confounders such as antipsychotic medication, smoking, socio-economic status and unhealthy lifestyle make it impossible to solely attribute the earlier onset of aging-related changes or oxidative stress to having a diagnosis of schizophrenia. Regardless of whether oxidative stress can be attributed solely to a diagnosis of schizophrenia or whether it is due to other factors associated with schizophrenia, the available evidence is in support of increased oxidative stress-induced cellular damage of macromolecules which may play a role in the phenomenon of accelerated aging presumed to be associated with schizophrenia.

  1. Acceleration of Age-Associated Methylation Patterns in HIV-1-Infected Adults

    Science.gov (United States)

    Sehl, Mary; Sinsheimer, Janet S.; Hultin, Patricia M.; Hultin, Lance E.; Quach, Austin; Martínez-Maza, Otoniel; Horvath, Steve; Vilain, Eric; Jamieson, Beth D.

    2015-01-01

    Patients with treated HIV-1-infection experience earlier occurrence of aging-associated diseases, raising speculation that HIV-1-infection, or antiretroviral treatment, may accelerate aging. We recently described an age-related co-methylation module comprised of hundreds of CpGs; however, it is unknown whether aging and HIV-1-infection exert negative health effects through similar, or disparate, mechanisms. We investigated whether HIV-1-infection would induce age-associated methylation changes. We evaluated DNA methylation levels at >450,000 CpG sites in peripheral blood mononuclear cells (PBMC) of young (20-35) and older (36-56) adults in two separate groups of participants. Each age group for each data set consisted of 12 HIV-1-infected and 12 age-matched HIV-1-uninfected samples for a total of 96 samples. The effects of age and HIV-1 infection on methylation at each CpG revealed a strong correlation of 0.49, pmodules; module 3 (ME3) was significantly correlated with age (cor=0.70) and HIV-1 status (cor=0.31). Older HIV-1+ individuals had a greater number of hypermethylated CpGs across ME3 (p=0.015). In a multivariate model, ME3 was significantly associated with age and HIV status (Data set 1: βage= 0.007088, p=2.08 x 10-9; βHIV= 0.099574, p=0.0011; Data set 2: βage= 0.008762, p=1.27x 10-5; βHIV= 0.128649, p= 0.0001). Using this model, we estimate that HIV-1 infection accelerates age-related methylation by approximately 13.7 years in data set 1 and 14.7 years in data set 2. The genes related to CpGs in ME3 are enriched for polycomb group target genes known to be involved in cell renewal and aging. The overlap between ME3 and an aging methylation module found in solid tissues is also highly significant (Fisher-exact p=5.6 x 10-6, odds ratio=1.91). These data demonstrate that HIV-1 infection is associated with methylation patterns that are similar to age-associated patterns and suggest that general aging and HIV-1 related aging work through some common cellular

  2. Gamma radiation and magnetic field mediated delay in effect of accelerated ageing of soybean

    International Nuclear Information System (INIS)

    Mahesh Kumar; Anand, Anjali; Singh, Bhupinder; Ahuja, Sumedha; Dahuja, Anil

    2015-01-01

    Soybean seeds were exposed to gamma radiation (0.5, 1, 3 and 5 kGy), static magnetic field (50, 100 and 200 mT) and a combination of gamma radiation and magnetic energy (0.5 kGy+200 mT and 5 kGy+50 mT) and stored at room temperature for six months. These seeds were later subjected to accelerated ageing treatment at 42°C temperature and 95-100 % relative humidity and were compared for various physical and biochemical characteristics between the untreated and the energized treatments. Energy treatment protected the quality of stored seeds in terms of its protein and oil content. Accelerated aging conditions, however, affected the oil and protein quantity and quality of seed negatively. Antioxidant enzymes exhibited a decline in their activity during aging while the LOX activity, which reflects the rate of lipid peroxidation, in general, increased during the aging. Gamma irradiated (3 and 5 kGy) and magnetic field treated seeds (100 and 200 mT) maintained a higher catalase and ascorbate peroxidase activity which may help in efficient scavenging of deleterious free radical produced during the aging. Aging caused peroxidative changes to lipids, which could be contributed to the loss of oil quality. Among the electromagnetic energy treatments, a dose of 1-5 kGy of gamma and 100 mT, 200 mT magnetic field effectively slowed the rate of biochemical degradation and loss of cellular integrity in seeds stored under conditions of accelerated aging and thus, protected the deterioration of seed quality. Energy combination treatments did not yield any additional protection advantage. (author)

  3. Reproducing ten years of road ageing - Accelerated carbonation and leaching of EAF steel slag

    International Nuclear Information System (INIS)

    Suer, Pascal; Lindqvist, Jan-Erik; Arm, Maria; Frogner-Kockum, Paul

    2009-01-01

    Reuse of industrial aggregates is still hindered by concern for their long-term properties. This paper proposes a laboratory method for accelerated ageing of steel slag, to predict environmental and technical properties, starting from fresh slag. Ageing processes in a 10-year old asphalt road with steel slag of electric arc furnace (EAF) type in the subbase were identified by scanning electron microscopy (SEM) and leaching tests. Samples from the road centre and the pavement edge were compared with each other and with samples of fresh slag. It was found that slag from the pavement edge showed traces of carbonation and leaching processes, whereas the road centre material was nearly identical to fresh slag, in spite of an accessible particle structure. Batches of moisturized road centre material exposed to oxygen, nitrogen or carbon dioxide (CO 2 ) were used for accelerated ageing. Time (7-14 days), temperature (20-40 o C) and initial slag moisture content (8-20%) were varied to achieve the carbonation (decrease in pH) and leaching that was observed in the pavement edge material. After ageing, water was added to assess leaching of metals and macroelements. 12% moisture, CO 2 and seven days at 40 o C gave the lowest pH value. This also reproduced the observed ageing effect for Ca, Cu, Ba, Fe, Mn, Pb, Ca (decreased leaching) and for V, Si, and Al (increased leaching). However, ageing effects on SO 4 , DOC and Cr were not reproduced.

  4. Effects of Fibers on Color and Translucency Changes of Bulk-Fill and Anterior Composites after Accelerated Aging

    Directory of Open Access Journals (Sweden)

    Ali Riza Tuncdemir

    2018-01-01

    Full Text Available The aim of this study was to determine the effects of glass and polyethylene fibers on the color and translucency change of bulk-fill and anterior composites before and after artificial accelerated aging (AAA. Two types of teflon molds were used to fabricate samples which were 13 mm in diameter and, respectively, 2 mm and 4 mm in height. Polyethylene fiber (PF and glass fiber (GF were incorporated in the middle of the composite samples. Color and translucency changes of each composite were evaluated before and after AAA with spectrophotometer. ANOVA and Tukey’s HSD post hoc statistical analysis were used at a significance level of 0.05. Before AAA (for anterior composites, there were no significant differences in L* and b* parameters among the three groups (p>0.05; there were no significant differences in L* parameter between PF and GF groups or in TP between GF and control groups (p>0.05 (for bulk-fill composites. After AAA, there were no significant differences in L* parameter between GF and control groups, in a* parameter between PF and control groups, in b* parameter among all groups, or in TP parameter between GF and control groups (p>0.05. Fiber reinforcement led to color and TP change in both anterior and bulk-fill resin composites.

  5. Effect of chemical disinfectants and accelerated aging on maxillofacial silicone elastomers: An In vitro Study

    Directory of Open Access Journals (Sweden)

    Anna Serene Babu

    2018-01-01

    Full Text Available Context: Maxillofacial prostheses need frequent refabrication due to degradation of color and deterioration of physical properties of the elastomer. Aims: This study attempted to evaluate the change in color stability, Shore A hardness, and surface roughness of two maxillofacial silicones, A-2186 and Cosmesil M511, when submitted to chemical disinfection and accelerated aging. Settings and Design: This was a comparative in vitro study. Subjects and Methods: The materials included two silicone elastomers – A-2186 and Cosmesil M511 (Factor II Incorporated – functional intrinsic red pigment and three disinfectants – Fittydent tablet, chlorhexidine gluconate 4%, and neutral soap. The specimens in each group of elastomer were evaluated initially for color, hardness, and surface roughness, which were further divided into subgroups and subjected to disinfection and accelerated aging. The evaluation of color was performed with the help of an ultraviolet reflectance spectrophotometer. Shore A hardness was evaluated using a durometer and surface roughness, with a digital roughness tester followed by scanning electron microscopy analysis. Statistical Analysis Used: Analysis of variance and Tukey's multiple comparison test were used for statistical analysis. Results: Accelerated aging caused a significant decrease in color, increase in Shore A hardness, and variation in surface roughness in both silicone elastomer groups. Chemical disinfection presented significant changes in color and surface roughness whereas no significant effect on Shore hardness, irrespective of the disinfectant used. Conclusions: The maxillofacial silicone elastomers presented deterioration in color, hardening, and significant variations in surface roughness when subjected to chemical disinfection and accelerated aging, which provides a valid baseline for future research.

  6. A comparison of POPs bioaccumulation in Eisenia fetida in natural and artificial soils and the effects of aging.

    Science.gov (United States)

    Vlčková, Klára; Hofman, Jakub

    2012-01-01

    The close relationship between soil organic matter and the bioavailability of POPs in soils suggests the possibility of using it for the extrapolation between different soils. The aim of this study was to prove that TOC content is not a single factor affecting the bioavailability of POPs and that TOC based extrapolation might be incorrect, especially when comparing natural and artificial soils. Three natural soils with increasing TOC and three artificial soils with TOC comparable to these natural soils were spiked with phenanthrene, pyrene, lindane, p,p'-DDT, and PCB 153 and studied after 0, 14, 28, and 56 days. At each sampling point, total soil concentration and bioaccumulation in earthworms Eisenia fetida were measured. The results showed different behavior and bioavailability of POPs in natural and artificial soils and apparent effects of aging on these differences. Hence, direct TOC based extrapolation between various soils seems to be limited. Copyright © 2011 Elsevier Ltd. All rights reserved.

  7. Accelerated aging embrittlement of cast duplex stainless steel: Activation energy for extrapolation

    International Nuclear Information System (INIS)

    Chung, H.M.; Chopra, O.K.

    1989-05-01

    Cast duplex stainless steels, used extensively in LWR systems for primary pressure boundary components such as primary coolant pipes, valves, and pumps, are susceptible to thermal aging embrittlement at reactor operating or higher temperatures. Since a realistic aging embrittlement for end-of-life or life-extension conditions (i.e., 32--50 yr of aging at 280--320 degree C) cannot be produced, it is customary to simulate the metallurgical structure by accelerated aging at ∼400 degree C. Over the past several years, extensive data on accelerated aging have been reported from a number of laboratories. The most important information from these studies is the activation energy, namely, the temperature dependence of the aging kinetics between 280 and 400 degree C, which is used to extrapolate the aging characteristics to reactor operating conditions. The activation energies (in the range of 18--50 kcal/mole) are, in general, sensitive to material grade, chemical composition, and fabrication process, and a few empirical correlations, obtained as a function of bulk chemical composition, have been reported. In this paper, a mechanistic understanding of the activation energy is described on the basis of the results of microstructural characterization of various heats of CF-3, -8, and -8M grades that were used in aging studies at different laboratories. The primary mechanism of aging embrittlement at temperatures between 280 and 400 degree C is the spinodal decomposition of the ferrite phase, and M 23 C 6 carbide precipitation on the ferrite/austenite boundaries is the secondary mechanism for high-carbon CF-8 grade. 20 refs., 10 figs., 3 tabs

  8. Accelerated Aging during Chronic Oxidative Stress: A Role for PARP-1

    Directory of Open Access Journals (Sweden)

    Daniëlle M. P. H. J. Boesten

    2013-01-01

    Full Text Available Oxidative stress plays a major role in the pathophysiology of chronic inflammatory disease and it has also been linked to accelerated telomere shortening. Telomeres are specialized structures at the ends of linear chromosomes that protect these ends from degradation and fusion. Telomeres shorten with each cell division eventually leading to cellular senescence. Research has shown that poly(ADP-ribose polymerase-1 (PARP-1 and subtelomeric methylation play a role in telomere stability. We hypothesized that PARP-1 plays a role in accelerated aging in chronic inflammatory diseases due to its role as coactivator of NF-κb and AP-1. Therefore we evaluated the effect of chronic PARP-1 inhibition (by fisetin and minocycline in human fibroblasts (HF cultured under normal conditions and under conditions of chronic oxidative stress, induced by tert-butyl hydroperoxide (t-BHP. Results showed that PARP-1 inhibition under normal culturing conditions accelerated the rate of telomere shortening. However, under conditions of chronic oxidative stress, PARP-1 inhibition did not show accelerated telomere shortening. We also observed a strong correlation between telomere length and subtelomeric methylation status of HF cells. We conclude that chronic PARP-1 inhibition appears to be beneficial in conditions of chronic oxidative stress but may be detrimental under relatively normal conditions.

  9. Accelerated Aging Effect on Epoxy-polysiloxane Polymeric Insulator Material with Rice Husk Ash Filler

    Directory of Open Access Journals (Sweden)

    Rochmadi .

    2012-12-01

    Full Text Available The performances of outdoor polymeric insulators are influenced by environmental conditions. This paper presents the effect of artificial tropical climate on the hydrophobicity, equivalent salt deposit density (ESDD, surface leakage current, flashover voltage, and surface degradation on epoxy-polysiloxane polymeric insulator materials with rice husk ash (RHA. Test samples are made at room temperature vulcanized (RTV of various composition of epoxy-polysiloxane with rice husk ash as filler. The aging was carried out in test chamber at temperature from 50oC to 62oC, relative humidity of 60% to 80%, and ultraviolet (UV  radiation 21.28 w/cm2 in daylight conditions for 96 hours. The experiment results showed that the flashover voltage fluctuates from 34.13 kV up to 40.92 kV and tends to decrease on each variation of material composition. The surface leakage current fluctuates and tends to increase. Test samples with higher filler content result greater hydrophobicity, smaller equivalent salt deposit density, and smaller critical leakage current, which caused the increase of the flashover voltage. Insulator material (RTVEP3 showed the best performance in tropical climate environment. Artificial tropical aging for short duration gives less effect to the surface degradation of epoxy-polysiloxane insulator material.

  10. "1"4C ages and calendar years of Japanese swords measured with accelerator mass spectrometry

    International Nuclear Information System (INIS)

    Nagata, Kazuhiro; Matsubara, Akihiro; Kokubu, Yoko; Nakamura, Toshio

    2016-01-01

    Steel of Japanese swords has been produced with Tatara process from iron sand and charcoal. Carbon dissolved in steel was absorbed from wooden charcoal fuel during the production of the steel. From the decay of "1"4C activity in the steel, the "1"4C age of Japanese sword can be determined. The "1"4C ages of 4 Japanese swords were measured with accelerator mass spectrometry and calibrated to calendar years. Each "1"4C age provided plural calendar year periods with definite probabilities, and one of the periods agreed with the production year of each sword that was determined from the sword master's name cut in the grip of his sword after taking the age range of charcoal used for steel production and usage for several generations of the same names of sword masters into account. (author)

  11. Monitoring migration and transformation of nanomaterials in polymeric composites during accelerated aging

    International Nuclear Information System (INIS)

    Vilar, G; Fernández-Rosas, E; Aubouy, L; Vázquez-Campos, S; Puntes, V; Jamier, V

    2013-01-01

    The incorporation of small amounts of nanoadditives in polymeric compounds can introduce new mechanical, physical, electrical, magnetic, thermal and/or optical properties. The properties of these advanced materials have enabled new applications in several industrial sectors (electronics, automotive, textile...). In particular, for the nanomaterials (NM) described in this work, multi-walled carbon nanotubes (MWCNT) and silicon dioxide nanoparticles (SiO 2 NP), the following properties have been described: MWCNT act as nucleating agents in thermoplastics, and change viscosity, affecting dispersion, orientation, and therefore mechanical, thermal, and electrical properties; and SiO 2 NP act as flame retardant and display improved electrical and mechanical properties. The work described here is focused on the evaluation of the migration and transformation of NM included in polymer nanocomposites (NC) during accelerated climatic ageing. To this aim, we generated polyamide 6 (PA6) NC with different degree of compatibility between the NM and the polymeric matrix. These NC were submitted to accelerated aging conditions to simulate outdoor conditions (simulation of the use phase of the polymeric NC). The NC contain as nanofillers MWCNT and SiO 2 NP with different surface properties to influence the compatibility with the polymeric matrix. The generated NC were evaluated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) with Energy-dispersive X-ray spectroscopy (EDX), thermogravimetry (TGA) and differential scanning calorimetry (DSC) before and after the aging process, to monitor the compatibility of the NM with the matrix: dispersion within the matrix, migration during aging, and modification of the polymer properties. The dispersion of SiO 2 NP in the NC depended on their compatibility with the matrix. However, independently of their compatibility with the matrix, SiO 2 NP were aggregated at the end of the accelerated aging process. In addition

  12. Monitoring migration and transformation of nanomaterials in polymeric composites during accelerated aging

    Science.gov (United States)

    Vilar, G.; Fernández-Rosas, E.; Puntes, V.; Jamier, V.; Aubouy, L.; Vázquez-Campos, S.

    2013-04-01

    The incorporation of small amounts of nanoadditives in polymeric compounds can introduce new mechanical, physical, electrical, magnetic, thermal and/or optical properties. The properties of these advanced materials have enabled new applications in several industrial sectors (electronics, automotive, textile...). In particular, for the nanomaterials (NM) described in this work, multi-walled carbon nanotubes (MWCNT) and silicon dioxide nanoparticles (SiO2 NP), the following properties have been described: MWCNT act as nucleating agents in thermoplastics, and change viscosity, affecting dispersion, orientation, and therefore mechanical, thermal, and electrical properties; and SiO2 NP act as flame retardant and display improved electrical and mechanical properties. The work described here is focused on the evaluation of the migration and transformation of NM included in polymer nanocomposites (NC) during accelerated climatic ageing. To this aim, we generated polyamide 6 (PA6) NC with different degree of compatibility between the NM and the polymeric matrix. These NC were submitted to accelerated aging conditions to simulate outdoor conditions (simulation of the use phase of the polymeric NC). The NC contain as nanofillers MWCNT and SiO2 NP with different surface properties to influence the compatibility with the polymeric matrix. The generated NC were evaluated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) with Energy-dispersive X-ray spectroscopy (EDX), thermogravimetry (TGA) and differential scanning calorimetry (DSC) before and after the aging process, to monitor the compatibility of the NM with the matrix: dispersion within the matrix, migration during aging, and modification of the polymer properties. The dispersion of SiO2 NP in the NC depended on their compatibility with the matrix. However, independently of their compatibility with the matrix, SiO2 NP were aggregated at the end of the accelerated aging process. In addition

  13. Evaluation of accelerated aging procedures of painted galvanised steels by EIS

    Energy Technology Data Exchange (ETDEWEB)

    Fedrizzi, L. [Department of Chemical Science and Technology, University of Udine, Via Cotonificio 108, 33100 Udine (Italy)]. E-mail: lorenzo.fedrizzi@uniud.it; Bergo, A. [Department of ICMMPM, University of Rome ' La Sapienza' , Via Eudossiana 18, 00184 Rome (Italy); Fanicchia, M. [Department of ICMMPM, University of Rome ' La Sapienza' , Via Eudossiana 18, 00184 Rome (Italy)

    2006-01-20

    Coil-coated sheets are usually cut and shaped or deep drawn to obtain the final profile of the manufacture. Mechanical deformation can affect the barrier properties of an organic coating and the adhesion to the substrate, thus accelerating degradation by natural weathering. UV radiations too can deeply affect the barrier properties of organic coatings and contribute along with rain, snow, thermal and hygrometric cycles and other factors to a fast decaying of the anticorrosive properties of painted systems. In this work some coil coating products for outdoor exposure, were subjected to the combined action of UV irradiation and mechanical deformation in order to simulate some of the stress occurring in their actual use. After mechanical deformation and UV irradiation, samples were exposed to a proper thermal cycle in order to accelerate water uptake and to discriminate in very short time among different formulations. Electrochemical impedance spectroscopy (EIS) was used to monitor the evolution of the systems during the accelerated aging. Qc and Rp (i.e. the constant phase element describing the dielectric properties and the ionic resistance of the coating) were selected to describe the protective system evolution. Adhesive and barrier properties were monitored and discussed during the combined thermal-mechanical and photo-oxidative aging.

  14. Characterization and Accelerated Ageing of UHMWPE Used in Orthopedic Prosthesis by Peroxide

    Science.gov (United States)

    Rocha, Magda; Mansur, Alexandra; Mansur, Herman

    2009-01-01

    Ultra-high molecular weight polyethylene (UHMWPE) has been the most commonly used bearing material in total joint arthroplasty. Wear and oxidation fatigue resistance of UHMWPE are regarded as two important mechanical properties to extend the longevity of knee prostheses. Though accelerated in vitro protocols have been developed to test the relative oxidation resistance of various types of UHMWPE, its mechanism is not accurately understood yet. Thus, in the present study an accelerated ageing of UHMWPE in hydrogen peroxide solution was performed and relative oxidation was extensively characterized by Fourier Transformed Infrared Spectroscopy (FTIR) spectroscopy and the morphological changes were analyzed by Scanning Electron Microscopy (SEM). Different chemical groups of UHMWPE associated with the degradation reaction were monitored for over 120 days in order to evaluate the possible oxidation mechanism(s) which may have occurred. The results have provided strong evidence that the oxidation mechanism is rather complex, and two stages with their own particular first-order kinetics reaction patterns have been clearly identified. Furthermore, hydrogen peroxide has proven to be an efficient oxidative medium to accelerate ageing of UHMWPE.

  15. Evaluation of accelerated aging procedures of painted galvanised steels by EIS

    International Nuclear Information System (INIS)

    Fedrizzi, L.; Bergo, A.; Fanicchia, M.

    2006-01-01

    Coil-coated sheets are usually cut and shaped or deep drawn to obtain the final profile of the manufacture. Mechanical deformation can affect the barrier properties of an organic coating and the adhesion to the substrate, thus accelerating degradation by natural weathering. UV radiations too can deeply affect the barrier properties of organic coatings and contribute along with rain, snow, thermal and hygrometric cycles and other factors to a fast decaying of the anticorrosive properties of painted systems. In this work some coil coating products for outdoor exposure, were subjected to the combined action of UV irradiation and mechanical deformation in order to simulate some of the stress occurring in their actual use. After mechanical deformation and UV irradiation, samples were exposed to a proper thermal cycle in order to accelerate water uptake and to discriminate in very short time among different formulations. Electrochemical impedance spectroscopy (EIS) was used to monitor the evolution of the systems during the accelerated aging. Qc and Rp (i.e. the constant phase element describing the dielectric properties and the ionic resistance of the coating) were selected to describe the protective system evolution. Adhesive and barrier properties were monitored and discussed during the combined thermal-mechanical and photo-oxidative aging

  16. Intrauterine growth restriction programs an accelerated age-related increase in cardiovascular risk in male offspring

    Science.gov (United States)

    Dasinger, John Henry; Intapad, Suttira; Backstrom, Miles A.; Carter, Anthony J.

    2016-01-01

    Placental insufficiency programs an increase in blood pressure associated with a twofold increase in serum testosterone in male growth-restricted offspring at 4 mo of age. Population studies indicate that the inverse relationship between birth weight and blood pressure is amplified with age. Thus, we tested the hypothesis that intrauterine growth restriction programs an age-related increase in blood pressure in male offspring. Growth-restricted offspring retained a significantly higher blood pressure at 12 but not at 18 mo of age compared with age-matched controls. Blood pressure was significantly increased in control offspring at 18 mo of age relative to control counterparts at 12 mo; however, blood pressure was not increased in growth-restricted at 18 mo relative to growth-restricted counterparts at 12 mo. Serum testosterone levels were not elevated in growth-restricted offspring relative to control at 12 mo of age. Thus, male growth-restricted offspring no longer exhibited a positive association between blood pressure and testosterone at 12 mo of age. Unlike hypertension in male growth-restricted offspring at 4 mo of age, inhibition of the renin-angiotensin system with enalapril (250 mg/l for 2 wk) did not abolish the difference in blood pressure in growth-restricted offspring relative to control counterparts at 12 mo of age. Therefore, these data suggest that intrauterine growth restriction programs an accelerated age-related increase in blood pressure in growth-restricted offspring. Furthermore, this study suggests that the etiology of increased blood pressure in male growth-restricted offspring at 12 mo of age differs from that at 4 mo of age. PMID:27147668

  17. Accelerated Vascular Aging as a Paradigm for Hypertensive Vascular Disease: Prevention and Therapy.

    Science.gov (United States)

    Barton, Matthias; Husmann, Marc; Meyer, Matthias R

    2016-05-01

    Aging is considered the most important nonmodifiable risk factor for cardiovascular disease and death after age 28 years. Because of demographic changes the world population is expected to increase to 9 billion by the year 2050 and up to 12 billion by 2100, with several-fold increases among those 65 years of age and older. Healthy aging and prevention of aging-related diseases and associated health costs have become part of political agendas of governments around the world. Atherosclerotic vascular burden increases with age; accordingly, patients with progeria (premature aging) syndromes die from myocardial infarctions or stroke as teenagers or young adults. The incidence and prevalence of arterial hypertension also increases with age. Arterial hypertension-like diabetes and chronic renal failure-shares numerous pathologies and underlying mechanisms with the vascular aging process. In this article, we review how arterial hypertension resembles premature vascular aging, including the mechanisms by which arterial hypertension (as well as other risk factors such as diabetes mellitus, dyslipidemia, or chronic renal failure) accelerates the vascular aging process. We will also address the importance of cardiovascular risk factor control-including antihypertensive therapy-as a powerful intervention to interfere with premature vascular aging to reduce the age-associated prevalence of diseases such as myocardial infarction, heart failure, hypertensive nephropathy, and vascular dementia due to cerebrovascular disease. Finally, we will discuss the implementation of endothelial therapy, which aims at active patient participation to improve primary and secondary prevention of cardiovascular disease. Copyright © 2016 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

  18. [Artificial intelligence meeting neuropsychology. Semantic memory in normal and pathological aging].

    Science.gov (United States)

    Aimé, Xavier; Charlet, Jean; Maillet, Didier; Belin, Catherine

    2015-03-01

    Artificial intelligence (IA) is the subject of much research, but also many fantasies. It aims to reproduce human intelligence in its learning capacity, knowledge storage and computation. In 2014, the Defense Advanced Research Projects Agency (DARPA) started the restoring active memory (RAM) program that attempt to develop implantable technology to bridge gaps in the injured brain and restore normal memory function to people with memory loss caused by injury or disease. In another IA's field, computational ontologies (a formal and shared conceptualization) try to model knowledge in order to represent a structured and unambiguous meaning of the concepts of a target domain. The aim of these structures is to ensure a consensual understanding of their meaning and a univariant use (the same concept is used by all to categorize the same individuals). The first representations of knowledge in the AI's domain are largely based on model tests of semantic memory. This one, as a component of long-term memory is the memory of words, ideas, concepts. It is the only declarative memory system that resists so remarkably to the effects of age. In contrast, non-specific cognitive changes may decrease the performance of elderly in various events and instead report difficulties of access to semantic representations that affect the semantics stock itself. Some dementias, like semantic dementia and Alzheimer's disease, are linked to alteration of semantic memory. We propose in this paper, using the computational ontologies model, a formal and relatively thin modeling, in the service of neuropsychology: 1) for the practitioner with decision support systems, 2) for the patient as cognitive prosthesis outsourced, and 3) for the researcher to study semantic memory.

  19. Accelerated long-term forgetting in aging and intra-sleep awakenings

    Directory of Open Access Journals (Sweden)

    Alison eMary

    2013-10-01

    Full Text Available The architecture of sleep and the functional neuroanatomical networks subtending memory consolidation processes are both modified with aging, possibly leading to accelerated forgetting in long-term memory. We investigated associative learning and declarative memory consolidation processes in 16 young (18–30 years and 16 older (65–75 years healthy adults. Performance was tested using a cued recall procedure at the end of learning (immediate recall, and 30 minutes and 7 days later. A delayed recognition test was also administered on day 7. Daily sleep diaries were completed during the entire experiment. Results revealed a similar percentage of correct responses at immediate and 30-minute recall in young and older participants. However, recall was significantly decreased 7 days later, with an increased forgetting in older participants. Additionally, intra-sleep awakenings were more frequent in older participants than young adults during the 7 nights, and were negatively correlated with delayed recall performance on day 7 in the older group. Altogether, our results suggest a decline in verbal declarative memory consolidation processes with aging, eventually leading to accelerated long-term forgetting indicating that increased sleep fragmentation due to more frequent intra-sleep awakenings in older participants contribute to the reported age-related decline in long-term memory retrieval. Our results highlight the sensitivity of long-term forgetting measures to evidence consolidation deficits in healthy aging.

  20. The influence of the accelerated ageing on the black screen element of the Electroink prints

    Energy Technology Data Exchange (ETDEWEB)

    Majnaric, I; Bolanca, Z; Mirkovic, I Bolanca, E-mail: majnaric@grf.h, E-mail: zbolanca@grf.h, E-mail: ibolanca@grf.h [University of Zagreb Faculty of Graphic Arts, Getaldiceva 2, 10 000 Zagreb (Croatia)

    2010-06-01

    Printing material and prints undergo changes during ageing which can be recognized in deterioration in the physical, chemical and optical properties. The aim of this work is to determine the optical changes of the prints caused by ageing of the printing material and of the prints obtained by the application of the indirect electrophotography. The change of the screen elements in lighter halftone areas, which was obtained by the usage of the microscopic image analysis, has been discussed in the article. For the preparation of samples the following papers were used: fine art paper, recycled paper and offset paper as well as black Electroink. Three sample series were observed: prints on nonaged paper and ElectroInk, prints on aged paper and ElectroInk and prints on aged paper and nonaged ElectroInk. The investigation results show that by ageing of the uncoated printing substrates the decrease of the dots on prints can be expected, while the printing on the aged paper results in the increased reproduction of the halftone dots. The obtained results are the contribution to the explanation of the influence of the accelerated ageing process of papers which are used for printing and the aged prints on the halftone dot changes. Except the mentioned determined scientific contribution the results are applicable in the area of the printing product quality as well as in the forensic science.

  1. The influence of the accelerated ageing on the black screen element of the Electroink prints

    International Nuclear Information System (INIS)

    Majnaric, I; Bolanca, Z; Mirkovic, I Bolanca

    2010-01-01

    Printing material and prints undergo changes during ageing which can be recognized in deterioration in the physical, chemical and optical properties. The aim of this work is to determine the optical changes of the prints caused by ageing of the printing material and of the prints obtained by the application of the indirect electrophotography. The change of the screen elements in lighter halftone areas, which was obtained by the usage of the microscopic image analysis, has been discussed in the article. For the preparation of samples the following papers were used: fine art paper, recycled paper and offset paper as well as black Electroink. Three sample series were observed: prints on nonaged paper and ElectroInk, prints on aged paper and ElectroInk and prints on aged paper and nonaged ElectroInk. The investigation results show that by ageing of the uncoated printing substrates the decrease of the dots on prints can be expected, while the printing on the aged paper results in the increased reproduction of the halftone dots. The obtained results are the contribution to the explanation of the influence of the accelerated ageing process of papers which are used for printing and the aged prints on the halftone dot changes. Except the mentioned determined scientific contribution the results are applicable in the area of the printing product quality as well as in the forensic science.

  2. Changes in opalescence and fluorescence properties of resin composites after accelerated aging.

    Science.gov (United States)

    Lee, Yong-Keun; Lu, Huan; Powers, John M

    2006-07-01

    Opalescence and fluorescence properties and the correlated translucency and masking effect of resin composites may change after aging. The objective of this study was to determine the changes in opalescence and fluorescence properties of resin composites after accelerated aging for 150 kJ/m2. Changes in translucency and masking effect were also determined. Color and spectral distribution of seven resin composites (A2 shade, 1-mm thick) were measured in the reflectance and transmittance modes under ultraviolet light (UV)-included and excluded conditions. Opalescence parameter (OP) was calculated as the difference in yellow-blue (Deltab*) and red-green (Deltaa*) coordinates between the reflected and transmitted colors under UV-included and excluded conditions. For the fluorescence evaluation, color differences (FL-Ref and FL-Trans) by the inclusion or exclusion of the UV-component of the standard illuminant D65 in the reflectance and transmittance modes were calculated. Under UV-included and excluded conditions, the translucency parameter (TP) was calculated, and the masking effect (ME) was calculated as the color difference between a specimen over a black tile and black tile itself. Repeated-measures 2-way analysis of variance at the significance level of 0.05 was performed for the values before and after aging. OP values in UV-included and excluded conditions did not change significantly after aging. FL-Ref and FL-Trans, TP values and ME values in UV-included and excluded conditions changed significantly after aging (pOpalescence of resin composites did not change but fluorescence was not detected after accelerated aging for 150 kJ/m2. Translucency and masking effect changed significantly after aging.

  3. Evaluation of color and radon exhalation rate in granite rocks between accelerated aging cycles

    International Nuclear Information System (INIS)

    Silva, Francisco Diones Oliveira

    2016-01-01

    Data used for the assessment of the analyzes performed on three types of dimension stone (Juparana Bordeaux, Branco Nevasca and Golden Artico), in natural state and after several cycles of accelerated aging are presented, correlating them with the gas exhalation rate radon issued by the analyzed lithologies. In the samples were conducted permeability, porosity, colorimetry, image analysis, petrographic and exhalation rate of radon, accompanied by aging tests on climate simulation chamber which simulates change situations of materials by weathering agents, accelerating wear and tear samples. The measurements were performed on samples in natural state, with 50 and 100 cycles of aging acceleration, where each cycle corresponds to variations in temperature and humidity in climatic simulation chamber, with the addition of an internal atmosphere of SO_2 with 25 concentration ppm. The results obtained during the tests were related to better analysis of the changes observed on the samples and the variation rate of exhalation radon emitted. The rocks have radon concentration values above the limits suggested by relevant international agencies (200-400 Bq/m³), with average values in the natural state, in 6149, 1619 and 866 Bq/m³ for Juparana Bordeaux, Branco Nevasca and Golden Arctic, respectively. The other aging cycles (50 and 100 cycles) showed an average increase of 0.8% for Juparana Bordeaux, 6.9% for White Blizzard and -23.87% for the Golden Arctic, with 50 cycles. From 50 to 100 cycles, there was reduction of 3.43% for Juparana Bordeaux and 22.15% for Branco Nevasca and an increase of 13.82% in the Golden Artico. The porosity results in the natural state obtained values an average of 0.696% for Juparana Bordeaux, 0.919% for Branco Nevasca and 0.830% for Golden Artico, and after 50 cycles of accelerated aging, obtained 0.621% to Juparana Bordeaux, 0.910% for Branco Nevasca and 0.840% for Golden Artico. The permeability of the samples showed values in the natural

  4. Stability of prototype two-piece zirconia and titanium implants after artificial aging: an in vitro pilot study.

    Science.gov (United States)

    Kohal, Ralf-Joachim; Finke, Hans Christian; Klaus, Gerold

    2009-12-01

    Zirconia oral implants are a new topic in implant dentistry. So far, no data are available on the biomechanical behavior of two-piece zirconia implants. Therefore, the purpose of this pilot investigation was to test in vitro the fracture strength of two-piece cylindrical zirconia implants after aging in a chewing simulator. This laboratory in vitro investigation comprised three different treatment groups. Each group consisted of 16 specimens. In group 1, two-piece zirconia implants were restored with zirconia crowns (zirconia copings veneered with Triceram; Esprident, Ispringen, Germany), and in group 2 zirconia implants received Empress 2 single crowns (Ivoclar Vivadent AG, Schaan, Liechtenstein). The implants, including the abutments, in the two zirconia groups were identical. In group 3, similar titanium implants were reconstructed with porcelain-fused-to-metal crowns. Eight samples of each group were submitted to artificial aging with a long-term load test in the artificial mouth (chewing simulator). Subsequently, all not artificially aged samples and all artificially aged samples that survived the long-term loading of each group were submitted to a fracture strength test in a universal testing machine. For the pairwise comparisons in the different test groups with or without artificial loading and between the different groups at a given artificial loading condition, the Wilcoxon rank-sum test for independent samples was used. The significance level was set at 5%. One sample of group 1 (veneer fracture), none of group 2, and six samples of group 3 (implant abutment screw fractures) failed while exposed to the artificial mouth. The values for the fracture strength after artificial loading with 1.2 million cycles for group 1 were between 45 and 377 N (mean: 275.7 N), in group 2 between 240 and 314 N (mean: 280.7 N), and in the titanium group between 45 and 582 N (mean: 165.7 N). The fracture strength results without artificial load for group 1 amounted to between

  5. Early age sealing of buffer-rock gap by artificial wetting to induce bentonite swelling

    International Nuclear Information System (INIS)

    Holt, Erika; Marjavaara, Pieti

    2012-01-01

    Document available in extended abstract form only. The aim of this work is to study the homogeneous and rapid swelling of bentonite in the gap between the buffer blocks and the rock wall of the Olkiluoto disposal facility by artificial wetting. The focus was on the construction period of the deposition hole and buffer, and thus only the very early ages of the first weeks. In practice it is desirable that the bentonite material has a volume increase sufficient enough to prevent rock scaling while lowering the risks of bentonite piping and erosion due to potential water flow. This initial study was done in a small-scale mock-up in laboratory conditions. The small-scale steel mock-up had dimensions of 39 cm in height by 36 cm in diameter and included 12 pressure sensors, two displacement transducers, thermal couples, and pore water pressure measurements. The radial and axial pressure development was typically measured over a two week period to assess the rate and magnitude of sealing. A steel confining lid was used for simulating overpressure, though in some cases a plexiglass lid was used to take video images of the gap sealing. The buffer blocks were produced by isostatic compression of 100 MPa. The material was MX-80 Wyoming bentonite having a water content of approximately 13% and a dry density of 1890 kg/m 3 . The testing samples were dry sawn and core drilled from the large block and machined to their final dimensions. These were typically 30 x 30 cm, either as a solid block or three disks of 10 cm height each. The diameter was sometimes varied to allow for a change of gap width between 25 to 50 mm The study included various scenarios, such as: eccentric aligned blocks with gap sizes of 5 and 45 mm, free upward swelling or confinement, different types of pellet and granular gap filling, addition of water at varying rates, and longer term test duration. The samples were typically disassembled after two weeks. At this ending point, material assessments were done

  6. Aging Depth Test of Rubber Blocks by Accelerated Thermal Oxidation Test

    International Nuclear Information System (INIS)

    Park, Junhee; Choun, Young-Sun; Kim, Min Kyu

    2015-01-01

    In this study, the accelerated thermal oxidation tests of rubber block were performed to investigate the aging depth of rubber bearing. From the tests, it was found the critical aging depth in rubber block. Also the property variation of rubber was investigated along the depth. The deterioration pattern from the aging depth tests was found from surface to inside and the critical aging depth was to be about 10 mm. The analytical model for rubber bearing with aging can be developed based on the relationship between the property variation and aging depth investigated from this study. The mechanical properties of rubber bearings were changed with time. Because the aging effect of rubber material was generally higher than that of other structure materials it is needed that the aging properties of seismically isolators should be evaluated to ensure the safety of seismically isolated nuclear power plants (NPPs) over the lifetime. NRC and ASCE required the tests of seismically isolators for investigating the aging properties. JNES also required the seismic response analysis for the seismically isolated NPPs when the properties of seismically isolators were extremely changed. If the aging properties of seismically isolators such as rubber bearings are evaluated by analysis the analytical model of seismically isolators should be developed considering aging effect of rubber material. From the previous research, it was reported that the behavior of aged rubber material mainly affected by temperature and oxidation. The material properties between surface and inside can be different by the oxidation of rubber. Therefore, the aging depth should be investigated for exactly evaluating the seismic behavior of aged rubber bearing. The aging depth of rubber baring was not influenced by the size of seismically isolators but environment condition. Therefore, the detail analysis considering aging depth was not required for NPPs with large seismically isolators. But the seismic response

  7. Enhanced experimental tumor metastasis with age in senescence-accelerated mouse

    International Nuclear Information System (INIS)

    Shimizu, Kosuke; Kinouchi Shimizu, Naomi; Asai, Tomohiro; Oku, Naoto; Tsukada, Hideo

    2008-01-01

    Tumor metastasis is affected by the host immune surveillance system. Since aging may attenuate the host immune potential, the experimental tumor metastasis may be enhanced with age. In the present study, we investigated this alteration of experimental tumor metastasis with age. We used senescence-accelerated mice prone 10 (SAMP10) as a model of aged animals. Natural killer cell (NK) activity, as an indicator of immune surveillance potential, in 8-month-old (aged) SAMP10 mice was observed to be much lower than that in 2-month-old (young) mice. When we examined the in vivo trafficking of lung-metastatic K1735M2 melanoma cells in SAMP10 with positron emission tomography (PET), K1735M2 cells labeled with [2- 18 F]2-deoxy-2-fluoro-D-glucose ([ 18 F]FDG) were observed in both young and aged SAMP10 just after injection of the cells, whereas the clearance of 18 F from the lungs was retarded in aged animals. The accumulation of 5-[ 125 I]iodo-2'-deoxyuridine ([ 125 I]IUdR)-labeled K1735M2 cells in the lungs of SAMP10 at 24 h after injection was significantly higher in aged mice. Corresponding to these results, the number of metastatic colonies in the lung was larger in the aged SAMP10 of the experimental tumor metastasis model. The present study demonstrated that the aging process produced a susceptible environment allowing the tumor cells to metastasize due to decrease in the host immune surveillance potential with age. (author)

  8. Reproducing ten years of road ageing - Accelerated carbonation and leaching of EAF steel slag

    Energy Technology Data Exchange (ETDEWEB)

    Suer, Pascal, E-mail: pascal.suer@swedgeo.se [Swedish Geotechnical Institute, Linkoeping (Sweden); Lindqvist, Jan-Erik [Swedish Cement and Concrete Research Institute, Boras (Sweden); Arm, Maria; Frogner-Kockum, Paul [Swedish Geotechnical Institute, Linkoeping (Sweden)

    2009-09-01

    Reuse of industrial aggregates is still hindered by concern for their long-term properties. This paper proposes a laboratory method for accelerated ageing of steel slag, to predict environmental and technical properties, starting from fresh slag. Ageing processes in a 10-year old asphalt road with steel slag of electric arc furnace (EAF) type in the subbase were identified by scanning electron microscopy (SEM) and leaching tests. Samples from the road centre and the pavement edge were compared with each other and with samples of fresh slag. It was found that slag from the pavement edge showed traces of carbonation and leaching processes, whereas the road centre material was nearly identical to fresh slag, in spite of an accessible particle structure. Batches of moisturized road centre material exposed to oxygen, nitrogen or carbon dioxide (CO{sub 2}) were used for accelerated ageing. Time (7-14 days), temperature (20-40 {sup o}C) and initial slag moisture content (8-20%) were varied to achieve the carbonation (decrease in pH) and leaching that was observed in the pavement edge material. After ageing, water was added to assess leaching of metals and macroelements. 12% moisture, CO{sub 2} and seven days at 40 {sup o}C gave the lowest pH value. This also reproduced the observed ageing effect for Ca, Cu, Ba, Fe, Mn, Pb, Ca (decreased leaching) and for V, Si, and Al (increased leaching). However, ageing effects on SO{sub 4}, DOC and Cr were not reproduced.

  9. Accelerated aging of adhesive-mediated fiber post-resin composite bonds: A modeling approach.

    Science.gov (United States)

    Radovic, Ivana; Monticelli, Francesca; Papacchini, Federica; Magni, Elisa; Cury, Alvaro Hafiz; Vulicevic, Zoran R; Ferrari, Marco

    2007-08-01

    Although fiber posts luted in root canals are not directly exposed to oral fluids, water storage is considered as in vitro accelerated aging test for bonded interfaces. The aim of the study was to evaluate the influence of accelerated water aging on fiber post-resin composite adhesion. Forty fiber posts (DT Light Post, RTD) were randomly divided into two main groups, according to the surface treatment performed. Group I: XPBond adhesive (Dentsply Caulk); Group II: sandblasting (Rocatec-Pre, 3M ESPE) and XPBond. Dual-cured resin cement (Calibra, Dentsply Caulk) and flowable composite (X-Flow, Dentsply Caulk) were applied on the posts to produce cylindrical specimens. The bond strength at the interface between post and cement/composite was measured with the microtensile test according to the non-trimming technique. Half of the sticks were tested immediately for bond strength, while in the other half testing was performed after 1 month of water storage at 37 degrees C. Post-cement/composite interfaces were evaluated under SEM prior and after water aging. Statistical analysis was performed using the Kruskal-Wallis ANOVA followed by Dunn's multiple range test (p<0.05). Immediate bond strength was higher on sandblasted posts. After water aging the two post surface treatments resulted comparable in bond strength. Resin cement achieved higher bond strength to fiber posts than flowable composite. Water aging significantly reduced bond strength. Sandblasting followed by adhesive coating may improve immediate post-resin bond strength in comparison to adhesive alone. However, fiber post-resin bond strength mediated by hydrophilic adhesive tends to decrease after water aging.

  10. The hypothesis of radiation-accelerated aging and the mortality of Japanese A-bomb victims

    International Nuclear Information System (INIS)

    Beebe, G.W.; Land, C.E.; Kato, H.

    1978-01-01

    The hypothesis that ionizing radiation accelerates aging is extremely difficult to investigate in man except at the level of mortality. Among the 82000 Japanese A-bomb survivors being followed for mortality, there were 14400 deaths from non-neoplastic diseases from October 1950 to September 1974, and this experience has been analysed for evidence of a non-specific mortality differential associated with radiation dose (kerma). Cause of death has been classified as follows: neoplastic diseases individually and in various groupings, tuberculosis, cerebrovascular diseases, cardiovascular diseases other than cerebrovascular, diseases of blood and blood-forming organs, diseases of the digestive system, all other non-neoplastic diseases, and all non-neoplastic diseases. Although there is clear evidence of a radiation effect for many forms of cancer, mortality from other diseases contains little suggestion of a relationship to radiation dose. A superficial association between mortality from diseases of blood and blood-forming organs and radiation rests entirely on the carcinogenic effect of radiation, especially the leukaemogenic effect. Deaths from digestive diseases seem related to radiation dose but only in the 1971-74 period and among the Hiroshima survivors; the excess is small but occurred in all age groups. Thus far the mortality experience of the Japanese A-bomb survivors suggests that the life-shortening effect of whole-body human exposure to ionizing radiation derives from its carcinogenic effect, not from any acceleration of the aging process

  11. How accelerated biological aging can affect solar reflective polymeric based building materials

    Science.gov (United States)

    Ferrari, C.; Santunione, G.; Libbra, A.; Muscio, A.; Sgarbi, E.

    2017-11-01

    Among the main issues concerning building materials, in particular outdoor ones, one can identify the colonization by microorganisms referred to as biological aggression. This can affect not only the aesthetical aspect but also the thermal performance of solar reflective materials. In order to improve the reliability of tests aimed to assess the resistance to biological aggression and contextually reduce the test duration, an accelerated test method has been developed. It is based on a lab reproducible setup where specific and controlled environmental and boundary conditions are imposed to accelerate as much as possible biological growth on building materials. Due to their widespread use, polymeric materials have been selected for the present analysis, in the aim of reaching an advanced bio-aged level in a relatively short time (8 weeks or less) and at the same time comparatively evaluate different materials under a given set of ageing conditions. Surface properties before, during and after ageing have been investigated by surface, microstructural and chemical analyses, as well as by examination of time progressive images to assess bacterial and algal growth rate.

  12. Loss of circadian clock accelerates aging in neurodegeneration-prone mutants.

    Science.gov (United States)

    Krishnan, Natraj; Rakshit, Kuntol; Chow, Eileen S; Wentzell, Jill S; Kretzschmar, Doris; Giebultowicz, Jadwiga M

    2012-03-01

    Circadian clocks generate rhythms in molecular, cellular, physiological, and behavioral processes. Recent studies suggest that disruption of the clock mechanism accelerates organismal senescence and age-related pathologies in mammals. Impaired circadian rhythms are observed in many neurological diseases; however, it is not clear whether loss of rhythms is the cause or result of neurodegeneration, or both. To address this important question, we examined the effects of circadian disruption in Drosophila melanogaster mutants that display clock-unrelated neurodegenerative phenotypes. We combined a null mutation in the clock gene period (per(01)) that abolishes circadian rhythms, with a hypomorphic mutation in the carbonyl reductase gene sniffer (sni(1)), which displays oxidative stress induced neurodegeneration. We report that disruption of circadian rhythms in sni(1) mutants significantly reduces their lifespan compared to single mutants. Shortened lifespan in double mutants was coupled with accelerated neuronal degeneration evidenced by vacuolization in the adult brain. In addition, per(01)sni(1) flies showed drastically impaired vertical mobility and increased accumulation of carbonylated proteins compared to age-matched single mutant flies. Loss of per function does not affect sni mRNA expression, suggesting that these genes act via independent pathways producing additive effects. Finally, we show that per(01) mutation accelerates the onset of brain pathologies when combined with neurodegeneration-prone mutation in another gene, swiss cheese (sws(1)), which does not operate through the oxidative stress pathway. Taken together, our data suggest that the period gene may be causally involved in neuroprotective pathways in aging Drosophila. Copyright © 2011 Elsevier Inc. All rights reserved.

  13. Converging blockchain and next-generation artificial intelligence technologies to decentralize and accelerate biomedical research and healthcare

    OpenAIRE

    Mamoshina, Polina; Ojomoko, Lucy; Yanovich, Yury; Ostrovski, Alex; Botezatu, Alex; Prikhodko, Pavel; Izumchenko, Eugene; Aliper, Alexander; Romantsov, Konstantin; Zhebrak, Alexander; Ogu, Iraneus Obioma; Zhavoronkov, Alex

    2017-01-01

    The increased availability of data and recent advancements in artificial intelligence present the unprecedented opportunities in healthcare and major challenges for the patients, developers, providers and regulators. The novel deep learning and transfer learning techniques are turning any data about the person into medical data transforming simple facial pictures and videos into powerful sources of data for predictive analytics. Presently, the patients do not have control over the access priv...

  14. A comparison of POPs bioaccumulation in Eisenia fetida in natural and artificial soils and the effects of aging

    International Nuclear Information System (INIS)

    Vlčková, Klára; Hofman, Jakub

    2012-01-01

    The close relationship between soil organic matter and the bioavailability of POPs in soils suggests the possibility of using it for the extrapolation between different soils. The aim of this study was to prove that TOC content is not a single factor affecting the bioavailability of POPs and that TOC based extrapolation might be incorrect, especially when comparing natural and artificial soils. Three natural soils with increasing TOC and three artificial soils with TOC comparable to these natural soils were spiked with phenanthrene, pyrene, lindane, p,p′-DDT, and PCB 153 and studied after 0, 14, 28, and 56 days. At each sampling point, total soil concentration and bioaccumulation in earthworms Eisenia fetida were measured. The results showed different behavior and bioavailability of POPs in natural and artificial soils and apparent effects of aging on these differences. Hence, direct TOC based extrapolation between various soils seems to be limited. - Highlights: ► Artificial and natural soils with the same TOC content were used in this study. ► BAF and total concentration of five POPs were measured during 56 days after spiking. ► Bioaccumulation was significantly lower in NS than in AS with the same TOC. ► Direct extrapolation according to TOC was possible for soils with levels >10%. ► Microbial degradation probably influences PAHs bioavailability. - Organic matter is an important factor in the bioavailability of POPs in soils, but direct extrapolation based on TOC content might lead to incorrect results in risk assessment.

  15. Envelhecimento acelerado em sementes de trigo Accelerated aging in wheat seeds

    Directory of Open Access Journals (Sweden)

    Daniele Cardoso Pedroso

    2010-11-01

    Full Text Available O presente trabalho teve o objetivo de estudar procedimentos de condução do teste de envelhecimento acelerado para determinar o potencial fisiológico de sementes de trigo. Utilizaram-se quatro cultivares: 'Pampeano', 'Safira', 'Ônix' e 'Jaspe'. Foram realizadas determinações de teor de água e avaliações de germinação, emergência, índice de velocidade de emergência e teste de envelhecimento acelerado. O teste de envelhecimento acelerado foi conduzido de três formas: teste tradicional (água, teste com solução saturada de NaCl (11g de NaCl por 100mL de água e teste com solução supersaturada de NaCl (40g de NaCl por 100mL de água, nos períodos de 48, 72 e 96h de permanência na câmara de envelhecimento a 42°C. O teste de envelhecimento acelerado com solução saturada de NaCl, no período de 96h, foi o mais adequado para avaliar o potencial fisiológico das sementes de trigo, em alto, médio e baixo vigor.This research aimed to study procedures for conducting the accelerated aging test to determine the physiological potential of wheat seeds. The experiment was conducted with four varieties: 'Pampeano', 'Sapphire', Onyx' and 'Jasper'. Tests were performed with water content, germination, seedling emergence, speed of emergence and accelerated aging. The accelerated aging test was conducted in three stages: traditional (water, test using saturated NaCl solution (11g of NaCl per 100mL of water and with the use of supersaturated solution of NaCl (40g of NaCl per 100mL of water, each for 48, 72 and 96h at 42°C. The accelerated aging test with saturated solution of NaCl, within 96h was suitable to evaluate the physiological potential of seeds of wheat in high, medium and low vigor.

  16. Acceleration of age-associated methylation patterns in HIV-1-infected adults.

    Directory of Open Access Journals (Sweden)

    Tammy M Rickabaugh

    Full Text Available Patients with treated HIV-1-infection experience earlier occurrence of aging-associated diseases, raising speculation that HIV-1-infection, or antiretroviral treatment, may accelerate aging. We recently described an age-related co-methylation module comprised of hundreds of CpGs; however, it is unknown whether aging and HIV-1-infection exert negative health effects through similar, or disparate, mechanisms. We investigated whether HIV-1-infection would induce age-associated methylation changes. We evaluated DNA methylation levels at >450,000 CpG sites in peripheral blood mononuclear cells (PBMC of young (20-35 and older (36-56 adults in two separate groups of participants. Each age group for each data set consisted of 12 HIV-1-infected and 12 age-matched HIV-1-uninfected samples for a total of 96 samples. The effects of age and HIV-1 infection on methylation at each CpG revealed a strong correlation of 0.49, p<1 x 10(-200 and 0.47, p<1 x 10(-200. Weighted gene correlation network analysis (WGCNA identified 17 co-methylation modules; module 3 (ME3 was significantly correlated with age (cor=0.70 and HIV-1 status (cor=0.31. Older HIV-1+ individuals had a greater number of hypermethylated CpGs across ME3 (p=0.015. In a multivariate model, ME3 was significantly associated with age and HIV status (Data set 1: βage=0.007088, p=2.08 x 10(-9; βHIV=0.099574, p=0.0011; Data set 2: βage=0.008762, p=1.27 x 10(-5; βHIV=0.128649, p=0.0001. Using this model, we estimate that HIV-1 infection accelerates age-related methylation by approximately 13.7 years in data set 1 and 14.7 years in data set 2. The genes related to CpGs in ME3 are enriched for polycomb group target genes known to be involved in cell renewal and aging. The overlap between ME3 and an aging methylation module found in solid tissues is also highly significant (Fisher-exact p=5.6 x 10(-6, odds ratio=1.91. These data demonstrate that HIV-1 infection is associated with methylation patterns that

  17. Priming of microglia in a DNA-repair deficient model of accelerated aging.

    Science.gov (United States)

    Raj, Divya D A; Jaarsma, Dick; Holtman, Inge R; Olah, Marta; Ferreira, Filipa M; Schaafsma, Wandert; Brouwer, Nieske; Meijer, Michel M; de Waard, Monique C; van der Pluijm, Ingrid; Brandt, Renata; Kreft, Karim L; Laman, Jon D; de Haan, Gerald; Biber, Knut P H; Hoeijmakers, Jan H J; Eggen, Bart J L; Boddeke, Hendrikus W G M

    2014-09-01

    Aging is associated with reduced function, degenerative changes, and increased neuroinflammation of the central nervous system (CNS). Increasing evidence suggests that changes in microglia cells contribute to the age-related deterioration of the CNS. The most prominent age-related change of microglia is enhanced sensitivity to inflammatory stimuli, referred to as priming. It is unclear if priming is due to intrinsic microglia ageing or induced by the ageing neural environment. We have studied this in Ercc1 mutant mice, a DNA repair-deficient mouse model that displays features of accelerated aging in multiple tissues including the CNS. In Ercc1 mutant mice, microglia showed hallmark features of priming such as an exaggerated response to peripheral lipopolysaccharide exposure in terms of cytokine expression and phagocytosis. Specific targeting of the Ercc1 deletion to forebrain neurons resulted in a progressive priming response in microglia exemplified by phenotypic alterations. Summarizing, these data show that neuronal genotoxic stress is sufficient to switch microglia from a resting to a primed state. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. Marginal Gap Formation in Approximal "Bulk Fill" Resin Composite Restorations After Artificial Ageing.

    Science.gov (United States)

    Peutzfeldt, A; Mühlebach, S; Lussi, A; Flury, S

    The aim of this in vitro study was to investigate the marginal gap formation of a packable "regular" resin composite (Filtek Supreme XTE [3M ESPE]) and two flowable "bulk fill" resin composites (Filtek Bulk Fill [3M ESPE] and SDR [DENTSPLY DeTrey]) along the approximal margins of Class II restorations. In each of 39 extracted human molars (n=13 per resin composite), mesial and distal Class II cavities were prepared, placing the gingival margins below the cemento-enamel junction. The cavities were restored with the adhesive system OptiBond FL (Kerr) and one of the three resin composites. After restoration, each molar was cut in half in the oro-vestibular direction between the two restorations, resulting in two specimens per molar. Polyvinylsiloxane impressions were taken and "baseline" replicas were produced. The specimens were then divided into two groups: At the beginning of each month over the course of six months' tap water storage (37°C), one specimen per molar was subjected to mechanical toothbrushing, whereas the other was subjected to thermocycling. After artificial ageing, "final" replicas were produced. Baseline and final replicas were examined under the scanning electron microscope (SEM), and the SEM micrographs were used to determine the percentage of marginal gap formation in enamel or dentin. Paramarginal gaps were registered. The percentages of marginal gap formation were statistically analyzed with a nonparametric analysis of variance followed by Wilcoxon-Mann-Whitney tests and Wilcoxon signed rank tests, and all p-values were corrected with the Bonferroni-Holm adjustment for multiple testing (significance level: α=0.05). Paramarginal gaps were analyzed descriptively. In enamel, significantly lower marginal gap formation was found for Filtek Supreme XTE compared to Filtek Bulk Fill ( p=0.0052) and SDR ( p=0.0289), with no significant difference between Filtek Bulk Fill and SDR ( p=0.4072). In dentin, significantly lower marginal gap formation was

  19. Influence of artificial cavity age on red-cockaded woodpecker translocation success

    Science.gov (United States)

    Daniel Saenz; Richard R. Schaefer; Richard N. Conner; D. Craig Rudolph; Dawn K. Carrie; M. Stephen Best

    2004-01-01

    Red-cockaded woodpecker (Picoides borealis) translocations have been used to bolster woodpecker populations and to fill breeding vacancies. Artificial, insert cavities have been used to offset cavity shortages in woodpecker clusters and are the primary cavity type used in recruitment clusters in Texas and Arkansas, but inserts may lose their...

  20. Analysis of Samples Treated by Resistance Test Method Exposed to Accelerated Aging

    Directory of Open Access Journals (Sweden)

    Irena Bates

    2015-09-01

    Full Text Available Global awareness that packaging has to be fully adequate and of high quality, is gradually increasing. That is why printing inks and substrates, which have no detrimental effect on packed products, should be considered a compulsory precondition for food and tobacco packaging. Printing inks that have been developed in the recent years, especially for food and tobacco packaging, have low-odour and low migration into the printing substrate during the drying process. Their migration into the printing substrate is within the acceptable limits and has no detrimental effect in terms of food safety. Another extremely important element of prints in high quality food and tobacco packaging is their stability, as they have to be resistant to liquids and chemicals, which are a part of packed product. The selection of an appropriate printing substrate is also extremely relevant, since the interaction of substrate with printing inks should have zero effect on the packed product and should not change the physical appearance of packaging. This paper presents the results of analysing the stability of laboratory samples printed with low-migration inks, observed immediately after the printing (unaged and two treatments of accelerated aging. The accelerated aging of prints was conducted in order to simulate conditions in which food and tobacco packaging can be found due to the prolonged indoors storage. The stability of prints was analysed based on optical characteristics by observing the prints’ relative reflectance curves.

  1. Validation of accelerated ageing of Thales rotary Stirling cryocoolers for the estimation of MTTF

    Science.gov (United States)

    Seguineau, C.,; Cauquil, J.-M.; Martin, J.-Y.; Benschop, T.

    2016-05-01

    The cooled IR detectors are used in a wide range of applications. Most of the time, the cryocoolers are one of the components dimensioning the lifetime of the system. The current market needs tend to reliability figures higher than 15,000hrs in "standard conditions". Field returns are hardly useable mostly because of the uncertain environmental conditions of use, or the differences in user profiles. A previous paper explains how Thales Cryogenics has developed an approach based on accelerated ageing and statistical analysis [1]. The aim of the current paper is to compare results obtained on accelerated ageing on one side, and on the other side, specific field returns where the conditions of use are well known. The comparison between prediction and effective failure rate is discussed. Moreover, a specific focus is done on how some new applications of cryocoolers (continuous operation at a specific temperature) can increase the MTTF. Some assumptions are also exposed on how the failure modes, effects and criticality analysis evolves for continuous operation at a specific temperature and compared to experimental data.

  2. Major depressive disorder mediates accelerated aging in rats subjected to chronic mild stress.

    Science.gov (United States)

    Xie, Xiaoxian; Chen, Yangyang; Ma, Lingyan; Shen, Qichen; Huang, Liangfeng; Zhao, Binggong; Wu, Tao; Fu, Zhengwei

    2017-06-30

    Major depressive disorder (MDD) has a complex etiology and is characterized by a change in mood and psychophysiological state. MDD has been shown to mediate accelerated biological aging in patients, although the underlying mechanism is not well understood. In the present study, we used a chronic mild stress (CMS) paradigm to induce anhedonia, one of the main symptoms of MDD. CMS induced depression-like symptoms in rats, including reduced sucrose preference and increased immobility time in the forced swim test. Moreover, stressed rats travelled a shorter total distance, had fewer grid line crossings, and spent less time in the outer zone in the open field test than controls. CMS altered the levels of 5-hydroxytryptophan, dopamine, and corticosterone in the serum and hippocampus (P<0.05); these rats also exhibited impaired liver function, decreased telomerase activity, and telomere shortening, which was associated with increased oxidative damage along with decreased superoxide dismutase and glutathione reductase activities. Mitochondria in CMS-treated rats showed ultrastructural damage as well as reduced DNA content and integrity. These findings provide physiological and cellular evidence that the MDD can mediate accelerated aging in rats. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Thermal aging and accelerated weathering of HMSPP: structural and morphological studies

    International Nuclear Information System (INIS)

    Oliani, Washington L.; Komatsu, Luiz G.H.; Parra, Duclerc F.

    2015-01-01

    This work focuses of the influence of weathering factors - UV radiation, humidity, and temperature on the structure and morphology polypropylene with high melt strength (HMSPP), also called polypropylene modified by irradiation. The HMSPP was prepared from iPP (isotactic polypropylene) in presence of acetylene at 110 kPa pressure and irradiated with γ of "6"0Co at doses of 5, 12.5 and 20 kGy. It has been observed that HMSPP deteriorates the weathering resistance, the thermal behavior and the long-term stability of HMSPP, beyond substantial color changes. The samples aged were characterized by infrared spectroscopy (FTIR), optical microscopy (OM) and differential scanning calorimetry (DSC). The optical microscopy images on the surface show that thermal aging and artificial weathering proceed by different mechanisms. The effects of elevated temperature aging were evaluated in HMSPPs exposed surface according to the order: HMSPP 20 >12.5 > kGy >iPP, showing intense crack formation in surface exposed due to thermo oxidative degradation. (author)

  4. The Influences of Artificial Aging Temperature and Time on Pitting Susceptibility of SiCp/ AA2024 MMCs

    International Nuclear Information System (INIS)

    Kim, S. K.; Jo, C. J.; Kwon, B. H.; Hwang, W. S.

    2000-01-01

    The effects of artificial aging temperature and time were investigated on the pitting behaviors of SiCp/ AA2024 composites through measuring the changes of open circuit potential, pitting potential, and repassivation potential in a 3.5 wt% NaCl solution. And, the influence of microstructure on the pitting susceptibility was studied by measurement of TEM images. AA2024 Al alloy and 15vol%SiCp/ AA2024 composites were fabricated by vacuum hot pressing and hot extrusion with an extrusion ratio of 25 : 1. They were solutionized at 495 .deg. C for 4 hours, and aged at 130, 150, 170, and 190 .deg. C for 1, 2, 4, 8, and 16 hours. In aerated 3.5% NaCl solutions, the open circuit potential and pitting potential of both AA2024 alloy and composites were similar each other, and pitting occurred immediately at immersed condition. The pitting potential was decreased with increasing aging temperature and time. Also, the repassivation potential of SiCp/ AA2024 composites was decreased as increasing aging temperature and time. It was concluded that formation and growth of S' and S phase by artificial aging promoted the pitting susceptibility of SiCp/ AA2024 composites because these phases, easily soluble by forming galvanic couples with substrate Al alloy, served as preferential sites for nucleation of pits

  5. The signaling pathways by which the Fas/FasL system accelerates oocyte aging.

    Science.gov (United States)

    Zhu, Jiang; Lin, Fei-Hu; Zhang, Jie; Lin, Juan; Li, Hong; Li, You-Wei; Tan, Xiu-Wen; Tan, Jing-He

    2016-02-01

    In spite of great efforts, the mechanisms for postovulatory oocyte aging are not fully understood. Although our previous work showed that the FasL/Fas signaling facilitated oocyte aging, the intra-oocyte signaling pathways are unknown. Furthermore, the mechanisms by which oxidative stress facilitates oocyte aging and the causal relationship between Ca2+ rises and caspase-3 activation and between the cell cycle and apoptosis during oocyte aging need detailed investigations. Our aim was to address these issues by studying the intra-oocyte signaling pathways for Fas/FasL to accelerate oocyte aging. The results indicated that sFasL released by cumulus cells activated Fas on the oocyte by increasing reactive oxygen species via activating NADPH oxidase. The activated Fas triggered Ca2+ release from the endoplasmic reticulum by activating phospholipase C-γ pathway and cytochrome c pathway. The cytoplasmic Ca2+ rises activated calcium/calmodulin-dependent protein kinase II (CaMKII) and caspase-3. While activated CaMKII increased oocyte susceptibility to activation by inactivating maturation-promoting factor (MPF) through cyclin B degradation, the activated caspase-3 facilitated further Ca2+releasing that activates more caspase-3 leading to oocyte fragmentation. Furthermore, caspase-3 activation and fragmentation were prevented in oocytes with a high MPF activity, suggesting that an oocyte must be in interphase to undergo apoptosis.

  6. Anticipating and Training the Physician of the Future: The Importance of Caring in an Age of Artificial Intelligence.

    Science.gov (United States)

    Johnston, S Claiborne

    2018-02-13

    Artificial intelligence and other forms of information technology are only just beginning to change the practice of medicine. The pace of change is expected to accelerate as tools improve and as demands for analyzing a rapidly growing body of knowledge and array of data increase. The medical students of today will practice in a world where information technology is sophisticated and omnipresent. In this world, the tasks of memorization and analysis will be less important to them as practicing physicians. On the other hand, the non-analytical, humanistic aspects of medicine-most importantly, the art of caring-will remain a critical function of the physician, and facility with improving systems of care will be required. Communication, empathy, shared decision making, leadership, team building, and creativity are all skills that will continue to gain importance for physicians. These skills should be further prioritized in medical school curricula to produce an even more effective physician for the future.

  7. Effect of varying core thicknesses and artificial aging on the color difference of different all-ceramic materials.

    Science.gov (United States)

    Dikicier, Sibel; Ayyildiz, Simel; Ozen, Julide; Sipahi, Cumhur

    2014-11-01

    Clinicians should reserve all-ceramics with high translucency for clinical applications in which high-level esthetics are required. Furthermore, it is unclear whether a correlation exists between core thickness and color change. The aim of this study was to examine the effects of different core thicknesses and artificial aging on the color stability of three all-ceramic systems. Ninety disc-shaped cores with different thicknesses (0.5 mm, 0.8 mm and 1.0 mm) were prepared from three all-ceramic systems, In-Ceram Alumina (IC), IPS e.max Press (EM) and Katana (K). The colors of the samples were measured with a spectrophotometer and the color parameters (L*, a*, b*, ΔE) were calculated according to the CIE L*a*b* (Commission Internationale de L'Eclairage) color system before and after aging. The effects of aging on color parameters were statistically significant (p artificial aging affected color stability of the all-ceramic materials tested.

  8. Present status of TANDETRON accelerator age measurement facility in Nagoya University

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Toshio; Ikeda, Akiko; Ota, Tomoko; Okuno, Mitsuru; Oda, Hirotaka; Aoki, Hiroshi; Ito, Seisuke; Adachi, Mamoru [Nagoya Univ. (Japan)

    1996-12-01

    Already 14 years have elapsed since a TANDETRON accelerator mass analyzer was introduced in Nagoya University. During this period, the research on environmental C-14 concentration distribution and the C-14 age measurement of environmental samples have been carried out by using C-14 as the tracer. The number of measurement as of the end of 1995 exceeded 5800. The TANDETRON analyzer has been utilized for research and education as the joint utilization facility within the university. As to the performance of the TANDETRON analyzer, C-14 measurement is feasible with 0.2-1 mg of the CO{sub 2} for forming graphite. The measurable limit of old age is 40-50 thousand years age, and the error of measurement is {+-}0.8-{+-}1.0% for relatively young samples when graphite targets are used, which can be attained by the measurement of 2-3 hours. In the old samples exceeding 20,000 years ago, as the age value becomes larger, the error increases. The state of operation and utilization is reported. In Nagoya University, the carbon dating system of Model 4130 AMS made in Netherlands was introduced in fiscal year 1995. (K.I.)

  9. Aging and failure mode of electrochemical double layer capacitors during accelerated constant load tests

    Energy Technology Data Exchange (ETDEWEB)

    Koetz, R.; Ruch, P.W.; Cericola, D. [General Energy Research Department, Electrochemistry Laboratory, Paul Scherrer Institut, CH-5232 Villigen (Switzerland)

    2010-02-01

    Electrochemical double layer capacitors of the BCAP0350 type (Maxwell Technologies) were tested under constant load conditions at different voltages and temperatures. The aging of the capacitors was monitored during the test in terms of capacitance, internal resistance and leakage current. Aging was significantly accelerated by elevated temperature or increased voltage. Only for extreme conditions at voltages of 3.5 V or temperatures above 70 C the capacitors failed due to internal pressure build-up. No other failure events such as open circuit or short circuit were detected. Impedance measurements after the tests showed increased high frequency resistance, an increased distributed resistance and most likely an increase in contact resistance between electrode and current collector together with a loss of capacitance. Capacitors aged at elevated voltages (3.3 V) exhibited a tilting of the low frequency component, which implies an increase in the heterogeneity of the electrode surface. This feature was not observed upon aging at elevated temperatures (70 C). (author)

  10. Accelerated Age-Dependent Hippocampal Volume Loss in Parkinson Disease With Mild Cognitive Impairment.

    Science.gov (United States)

    Schneider, Christine B; Donix, Markus; Linse, Katharina; Werner, Annett; Fauser, Mareike; Klingelhoefer, Lisa; Löhle, Matthias; von Kummer, Rüdiger; Reichmann, Heinz; Storch, Alexander

    2017-09-01

    Patients with Parkinson disease are at high risk of developing dementia. During the course of the disease, a substantial number of patients will experience a cognitive decline, indicating the dynamics of the underlying neuropathology. Magnetic resonance imaging (MRI) has become increasingly useful for identifying structural characteristics in radiological brain anatomy existing prior to clinical symptoms. Whether these changes reflect pathology, whether they are aging related, or both often remains unclear. We hypothesized that aging-associated brain structural changes would be more pronounced in the hippocampal region among patients with Parkinson disease having mild cognitive deficits relative to cognitively unimpaired patients. Using MRI, we investigated 30 cognitively healthy patients with Parkinson disease and 33 patients with nondemented Parkinson disease having mild cognitive impairment. All participants underwent structural MRI scanning and extensive clinical and neuropsychological assessments. Irrespective of the study participants' cognitive status, older age was associated with reduced cortical thickness in various neocortical regions. Having mild cognitive impairment was not associated with an increased rate of cortical thinning or volume loss in these regions, except in the hippocampus bilaterally. Patients with Parkinson disease having mild cognitive impairment show an accelerated age-dependent hippocampal volume loss when compared with cognitively healthy patients with Parkinson disease. This may indicate pathological processes in a key region for memory functioning in patients with Parkinson disease at risk of developing dementia. Structural MRI of the hippocampal region could potentially contribute to identifying patients who should receive early treatment aimed at delaying the clinical onset of dementia.

  11. Time to regenerate: the doctor in the age of artificial intelligence

    OpenAIRE

    Liu, X.; Keane, P. A.; Denniston, A. K.

    2018-01-01

    Introduction We are experiencing a rapid expansion of new technologies which are fusing the digital and biological worlds. New digital technologies—such as artificial intelligence, electronic health records and Big Data, telemedicine, ‘wearables’ for home monitoring and virtual/augmented realities—are shaping the future of medicine to become more efficient, more accurate and more sustainable.1 Digital systems from industry leaders such as DeepMind and IBM Watson are already being tested fo...

  12. Responding to the will of the machine: Leadership in the age of artificial intelligence

    OpenAIRE

    NAQVI, Al

    2017-01-01

    Abstract. The advent of artificial intelligence in the modern economy will revolutionize the workplace of tomorrow. It will alsocreate never-seen-before challenges for leadership. The current leadership theory is extensive but it does not address on how to lead in a workplace composed of intelligent machines. However, it can be observed that leadership theory tends to develop in tandem with the developments in technology - metaphorically termed as will of the machine in this article. Specific...

  13. Investigation of the thermal decomposition of magnesium–sodium nitrate pyrotechnic composition (SR-524 and the effect of accelerated aging

    Directory of Open Access Journals (Sweden)

    Zaheer-ud-din Babar

    2017-03-01

    Full Text Available The aging behavior of the pyrotechnics is influenced by the storage atmosphere and more specifically on the temperature and humidity levels. The investigated composition SR 524 is a military pyrotechnic composition that is used as a tracer. The accelerated aging of the SR 524 composition has been carried out at a temperature of 70 °C and relative humidity of 70 percent. The results indicate that there is significant change in the thermal behavior, kinetic parameters and the morphology of the aged composition. The decomposition temperature and the activation energy were found to be lowered in the aged composition. The activation energy of the aged composition decreased nearly 57 percent. SEM micrographs of the aged composition revealed the development of micro cracks as a result of accelerated aging. XRD spectra of the aged composition showed the presence of magnesium hydroxide indicating the reaction between magnesium and water vapors present in the highly humid atmosphere.

  14. Effects evaluation of artificial aging by temperature and gamma radiation on cables for Laguna Verde nuclear power plant (LVNPP)

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez C, R. M.; Bonifacio M, J.; Garcia H, E. E.; Loperena Z, J. A. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Garcia M, C., E-mail: raulmario.vazquez@inin.gob.m [CFE, Central Nuclear Laguna Verde, Km. 42.5 Carretera Cardel-Nautla, Veracruz (Mexico)

    2010-10-15

    A set of tests has been carried out at the Equipment Qualification Laboratory at National Institute of Nuclear Research to perform accelerated aging up to 60 years under temperature and gamma radiation environment for electrical cables. The results obtained from such tests are the base line data for comparison to with the current cable conditions at the plant. This work is intended for establishing the cable aging management program for the Laguna Verde nuclear power plant (LVNPP). For such purpose, the Institute has prepared methodologies and procedures to apply condition monitoring techniques in accelerated aging tests on samples of new cables drawn from the LVNPP warehouse. The condition indicators of the material selected for condition monitoring and the aging management process of cables were: Elongation at Break (EAB) and Oxidation Induction Time (OIT). A cable aging management program includes activities for cable selection, determination of condition indicators of the cable materials (EAB, OIT, Ind enter), accelerated aging of cable samples at the laboratory, analysis of maintenance history, operational experience of the plant and analysis of the environmental and service conditions (temperature and gamma radiation), as well as the establishment of a condition monitoring plan for cables in the plant. Two cable model samples were thermally aged and gamma irradiated with doses corresponding to differential operational periods. EAB and OIT values of cable insulating material (ethylene propylene and cross linked polyethylene) were obtained. It was found that the EAB and OIT data correlation is very closed, and it could be applied to infer values that are not possible to measure directly at the plant and be used for cable aging evaluation and remaining life time determination. (Author)

  15. Soluble carbohydrates in cereal (wheat, rye, triticale seed after storage under accelerated ageing conditions

    Directory of Open Access Journals (Sweden)

    Agnieszka I. Piotrowicz-Cieślak

    2011-01-01

    Full Text Available Germinability and the content of soluble carbohydrates were analysed in cereal seed (winter rye, cv. Warko; spring wheat, cv. Santa; hexaploid winter triticale, cv. Fidelio and cv. Woltario. Seed moisture content (mc was equilibrated over silica gel to 0.08 g H2O/g dry mass and stored in a desiccator at 20oC for up to 205 weeks or were equilibrated to mc 0.06, 0.08 or 0.10 g H2O/g dm and subjected to artificial aging at 35oC in air-tight laminated aluminium foil packages for 205 weeks. It was shown that the rate of seed aging depended on the species and seed moisture content. The fastest decrease of germinability upon storage was observed in seed with the highest moisture level. Complete germinability loss for winter rye, winter triticale cv. Fidelio, winter triticale cv. Woltario and spring wheat seed with mc 0.10 g H2O/g dm3 occurred after 81, 81, 101 and 133 weeks, respectively. Fructose, glucose, galactose, myo-inositol, sucrose, galactinol, raffinose, stachyose and verbascose were the main soluble carbohydrates found in the seed. The obtained data on the contents of specific sugars and the composition of soluble sugars fraction in seed of rye, wheat and triticale did not corroborate any profound effect of reducing sugars, sucrose and oligosaccharides on seed longevity.

  16. Evaluation of Experimental Parameters in the Accelerated Aging of Closed-Cell Foam Insulation

    Energy Technology Data Exchange (ETDEWEB)

    Stovall, Therese K [ORNL; Vanderlan, Michael [ORNL; Atchley, Jerald Allen [ORNL

    2012-12-01

    The thermal conductivity of many closed-cell foam insulation products changes over time as production gases diffuse out of the cell matrix and atmospheric gases diffuse into the cells. Thin slicing has been shown to be an effective means of accelerating this process in such a way as to produce meaningful results. Efforts to produce a more prescriptive version of the ASTM C1303 standard test method led to the ruggedness test described here. This test program included the aging of full size insulation specimens for time periods of five years for direct comparison to the predicted results. Experimental parameters under investigation include: slice thickness, slice origin (at the surface or from the core of the slab), thin slice stack composition, product facings, original product thickness, product density, and product type. The test protocol has been completed and this report provides a detailed evaluation of the impact of the test parameters on the accuracy of the 5-year thermal conductivity prediction.

  17. Study on radiation sickness and aging using the senescense accelerated mouse

    International Nuclear Information System (INIS)

    Kondo, Hisayoshi; Kishikawa, Masao; Iseki, Masachika

    1989-01-01

    We compared several statistical methods for dealing with the results from the step-down passive avoidance test using the senescense accelerated mouse, which is recently used to investigate aging. Testing the difference of step-down latency between the irradiated group and control group, we often obtained conflicting results from different statistical methods. Step-down latency does not obey a normal distribution, and includes censoring observations. Therefore, the log rank test, which is usually regarded as one of the statistical methods for life time analysis, seems more suitable than t-test or Wilcoxon's rank-sum test for comparing step-down latency. Namely, the log rank test treats cases which step down within 180 seconds as failures and cases which do not step down within 180 seconds as censored cases. (author)

  18. Application of accelerator mass spectrometry on Environmental studies concerning ages of holocene fires in Central amazon forest

    International Nuclear Information System (INIS)

    Santos, G.M.; Gomes, P. R. S.; Anjos, R. M.; Lubian, J.; Cordeiro, R.C.; Turcq, B.; Sifeddine, A.; Di Tada, M.; Cresswell, R. G.; Fifield, L. K.

    1999-01-01

    The Accelerator Mass Spectrometry (AMS) technique was used to determine the radiocarbon age of Holocene fires in forests of the Amazon Region. Most of the ages were found to be within the 1000-1500 years range. These disturbances were probably caused by climatic anomalies, and they have modified the structure and dynamics of the region vegetation

  19. Colour-stability and gloss-retention of silorane and dimethacrylate composites with accelerated aging.

    Science.gov (United States)

    Furuse, Adilson Y; Gordon, Kathryn; Rodrigues, Flávia P; Silikas, Nick; Watts, David C

    2008-11-01

    To evaluate the colour-stability and gloss-retention of silorane versus dimethacrylate composites exposed to accelerated aging from daylight radiation. Five disc-shaped specimens of photo-cured resin-composites were prepared and manually polished for each material (Filtek Silorane, Herculite XRV, Tetric Evoceram and QuiXfil). Colour and gloss were evaluated before and after periods (baseline, 24, 72, 120 and 192 h) of accelerated photo-aging in xenon light following ISO 7491:2000. Colour measurements were performed with a colourimeter according to the CIE-Lab colour-space. The colour change (DeltaE) for each time was calculated. The surface gloss was measured using a glossmeter. Results were evaluated using one-way ANOVA and Tukey tests (alpha=0.05). Correlations between logtime, DeltaE and gloss were evaluated using Pearson's correlation (alpha=0.05). Materials generally decreased in L and a and increased in b. The strong exception was Filtek Silorane which maintained a and b. DeltaE was found to be a positive linear function of logtime for all materials. Materials varied in the magnitude and rate of increase of DeltaE with logtime: QuiXfil>Tetric EvoCeram>(Filtek Silorane>or=Herculite XRV). DeltaE remainedGloss was found to be a negative linear function of logtime. Gloss was maximal in the sequence: Filtek Silorane approximately Tetric EvoCeram>Herculite XRV>QuiXfil. Silorane gave the best overall performance in stability over time, compared to a set of representative dimethacrylate composites.

  20. Effect of Li level, artificial aging, and TiB2 reinforcement on the modulus of Weldalite (tm) 049

    Science.gov (United States)

    1991-01-01

    The dynamic Young's Modulus (E) was determined for (1) alloys 049(1.3)(heat 072), (2) 049(1.9), and (3) 049(1.3) TiB2 in the T3 temper and after aging at 160 C were made on a single 0.953 cm (0.375 in) cube to reduce scatter from microstructural inhomogeneities. Both shear and transverse wave velocities were measured for the L, LT, and ST directions by a pulse echo technique. These velocities were then used to calculate modulus. The change is shown in E with aging time at 160 C (320 F) for the three alloys. It is clear from the plots that aging has a minor, but measurable, influence on the E of alloys 049(1.3) and 049(1.9): E decreases by -2.5 pct. for 2 and 3 during the initial stages of artificial aging. This decrease in E generally follows the strength reversion. On further aging beyond the reversion well, E increases and then decreases again as the alloy overage. The slightly higher modulus in the T8 than in the T3 temper is consistent with the presence of the high modulus T sub 1 phase in the T8 temper. A similar change in E was observed on aging for the TiB2 reinforced variant that also follows the aging curve.

  1. Prokaryotic diversity and biochemical properties in aging artificial pit mud used for the production of Chinese strong flavor liquor.

    Science.gov (United States)

    Sun, Zhongke; Chen, Can; Hou, Xiaoge; Zhang, Jie; Tian, Fengshou; Li, Chengwei

    2017-10-01

    At present, artificial pit mud (APM) is widely used in Chinese liquor-making industry and plays a particular role in the production of Chinese strong flavor liquor (CSFL). However, APM frequently ages during fermentation, thus becoming unsuitable for sustainable use due to its low-quality. The reasons behind, and results of, APM aging during the production of CSFL are not yet understood. Sequencing the V4 region of the 16S rRNA gene shows that prokaryotic diversity is significantly decreased (Shannon's diversity index, P  aging APM. On the phylum level, the increase of Firmicutes and decrease of Proteobacteria are the main consequences of APM aging during the production of CSFL. The counting of cultivatable bacteria confirmed that there was a large increase in Lactobacilli and aerobic spore-forming bacteria in aging low-quality APM (more than twofold). Unexpectedly, the total number of caproic acid-producing bacteria, mainly Clostridia , did not change significantly between the two kinds of APM. Furthermore, biochemical analysis indicates that the pH and the levels of NH 4 + and K + are decreased in aging low-quality APM ( P  aging can be controlled potentially by adjustment of environmental factors and/or supplementation of diminished or missed microorganisms.

  2. The effect of copper, MDA, and accelerated aging on jet fuel thermal stability as measured by the gravimetric JFTOT

    Energy Technology Data Exchange (ETDEWEB)

    Pande, S.G. [Geo-Centers, Inc., Ft. Washington, MD (United States); Hardy, D.R. [Navy Technology Center for Safety and Survivability, Washington, DC (United States)

    1995-05-01

    Thermally unstable jet fuels pose operational problems. In order to adequately identify such fuels, factors that realistically impact on thermal stability were examined. Evaluation was based on a quantitative method of measuring thermal stability, viz., NRL`s recently developed gravimetric JFTOT. This method gives a quantitative measurement of both the strip deposit and filterables formed. The pertinent factors examined, included the individual and interactive effects of: soluble copper, MDA (metal deactivator), and aging. The latter was accelerated to simulate field conditions of approximately six months aging at ambient temperature and pressure. The results indicate that the individual and interactive effects of copper, MDA, and accelerated aging appear to be fuel dependent. Based on the results, the three test fuels examined (one JP-8 and two JP-5s) were categorized as exhibiting very good, typical, and poor thermal stabilities, respectively. For both the very good and poor thermal stability fuels, the effect of copper in conjunction with accelerated aging did not significantly increase the total thermal deposits of the neat fuels. In contrast, for the typical thermal stability fuel, the combined effects of copper and accelerated aging, did. Furthermore, the addition of MDA prior to aging of the copper-doped, typical stability fuel significantly counteracted the adverse effect of copper and aging. A similar beneficial effect of MDA was not observed for the poor stability fuel. These results focus on the compositional differences among fuels and the need to elucidate these differences (physical and chemical) for a better understanding and prediction of their performance.

  3. [Characteristics of the sympathoadrenal system response to psychoemotional stress under hypoxic conditions in aged people with physiological and accelerated aging of the respiratory system].

    Science.gov (United States)

    Asanov, E O; Os'mak, Ie D; Kuz'mins'ka, L A

    2013-01-01

    The peculiarities of the response of the sympathoadrenal system to psychoemotional and hypoxic stress in healthy young people and in aged people with physiological and accelerated aging of respiratory system were studied. It was shown that in aging a more pronounced response of the sympathoadrenal system to psychoemotional stress. At the same time, elderly people with different types of aging of the respiratory system did not demonstrate a difference in the response of the sympathoadrenal system to psychoemotional stress. Unlike in young people, in aged people, combination of psychoemotional and hypoxic stresses resulted in further activation of the sympathoadrenal system. The reaction of the sympathoadrenal system was more expressed in elderly people with accelerated ageing of the respiratory system.

  4. Cerebrospinal fluid metabolomics reveals altered waste clearance and accelerated aging in HIV patients with neurocognitive impairment

    Science.gov (United States)

    Cassol, Edana; Misra, Vikas; Dutta, Anupriya; Morgello, Susan; Gabuzda, Dana

    2014-01-01

    Objective(s): HIV-associated neurocognitive disorders (HAND) remain prevalent in HIV-infected patients on antiretroviral therapy (ART), but the underlying mechanisms are unclear. Some features of HAND resemble those of age-associated cognitive decline in the absence of HIV, suggesting that overlapping mechanisms may contribute to neurocognitive impairment. Design: Cross-sectional analysis of cerebrospinal fluid (CSF) from 100 individuals (46 HIV-positive patients and 54 HIV-negative controls). Methods: Untargeted CSF metabolite profiling was performed using liquid/gas chromatography followed by mass spectrometry. Cytokine profiling was performed by Bioplex. Bioinformatic analyses were performed in Metaboanalyst and R. Results: Alterations in the CSF metabolome of HIV patients on ART mapped to pathways associated with neurotransmitter production, mitochondrial function, oxidative stress, and metabolic waste. Many CSF metabolites altered in HIV overlapped with those altered with advanced age in HIV-negative controls, suggesting a pattern indicative of accelerated aging. Machine learning models identified neurotransmitters (glutamate, N-acetylaspartate), markers of glial activation (myo-inositol), and ketone bodies (beta-hydroxybutyric acid, 1,2-propanediol) as top-ranked classifiers of HAND. These CSF metabolites correlated with worse neurocognitive test scores, plasma inflammatory biomarkers [interferon (IFN)-α, IFN-γ, interleukin (IL)-8, IL-1β, IL-6, IL-2Ra], and intrathecal IFN responses (IFN-γ and kynurenine : tryptophan ratio), suggesting inter-relationships between systemic and intrathecal inflammation and metabolic alterations in CSF. Conclusions: Alterations in the CSF metabolome of HIV patients on ART suggest that persistent inflammation, glial responses, glutamate neurotoxicity, and altered brain waste disposal systems contribute to mechanisms involved in HAND that may be augmented with aging. PMID:24752083

  5. New accelerator mass spectrometry radiocarbon ages for the Mazama tephra layer from Kootenay National Park, British Columbia, Canada

    International Nuclear Information System (INIS)

    Hallett, D.J.; Hills, L.V.; Clague, J.J.

    1997-01-01

    Charcoal fragments recovered from the Mazama air-fall tephra layer in cores from Dog and Cobb lakes, Kootenay National Park, British Columbia, yielded accelerator mass spectrometry ages of 6720 ± 70 and 6760 ± 70 14 C years BP, respectively. These two new ages, together with other previously published radiocarbon ages on charcoal and twig fragments from Mazama air-fall deposits, indicate that the climatic eruption of Mount Mazama occurred 6730 ± 40 14 C years BP. (author)

  6. Accelerating Neuronal Aging in In Vitro Model Brain Disorders: a Focus on Reactive Oxygen Species

    Directory of Open Access Journals (Sweden)

    Priscila Britto Campos

    2014-10-01

    Full Text Available In this review, we discuss insights gained through the use of stem cell preparations regarding the modeling of neurological diseases, the need for aging neurons derived from pluripotent stem cells to further advance the study of late-onset adult neurological diseases, and the extent to which mechanisms linked to the mismanagement of ROS. The context of these issues can be revealed using the three disease states of Parkinson’s (PD, Alzheimer’s (AD, and schizophrenia, as considerable insights have been gained into these conditions through the use of stem cells in terms of disease etiologies and the role of oxidative stress. The latter subject is a primary area of interest of our group. After discussing the molecular models of accelerated aging, we highlight the role of ROS for the three diseases explored here. Importantly, we do not seek to provide an extensive account of all genetic mutations for each of the three disorders discussed in this review, but we aim instead to provide a conceptual framework that could maximize the gains from merging the approaches of stem cell microsystems and the study of oxidative stress in disease in order to optimize therapeutics and determine new molecular targets against oxidative stress that spare stem cell proliferation and development.

  7. Immune responses accelerate ageing: proof-of-principle in an insect model.

    Directory of Open Access Journals (Sweden)

    E Rhiannon Pursall

    Full Text Available The pathology of many of the world's most important infectious diseases is caused by the immune response. Additionally age-related disease is often attributed to inflammatory responses. Consequently a reduction in infections and hence inflammation early in life has been hypothesized to explain the rise in lifespan in industrialized societies. Here we demonstrate experimentally for the first time that eliciting an immune response early in life accelerates ageing. We use the beetle Tenebrio molitor as an inflammation model. We provide a proof of principle for the effects of early infection on morbidity late in life and demonstrate a long-lasting cost of immunopathology. Along with presenting a proof-of-principle study, we discuss a mechanism for the apparently counter-adaptive persistence of immunopathology in natural populations. If immunopathology from early immune response only becomes costly later in life, natural selection on reducing self-harm would be relaxed, which could explain the presence of immune self-harm in nature.

  8. A Study on Accelerated Thermal Aging of High Modulus Carbon/Epoxy Composite Material

    Directory of Open Access Journals (Sweden)

    Ju Min Kyung

    2015-01-01

    Full Text Available Composite materials have been used increasingly for various space applications due to the favorable characteristic of high modulus to density ratio and potential for near-zero coefficient of thermal expansion. In composite system, depending on the orientation of fibers, strength and stiffness can be changed so that the optimum structure can be accomplished. This is because the coefficient of thermal expansion (CTE of carbon fibers is negative. For spacecraft and orbiting space structure, which are thermally cycled by moving through the earth' shadow for at least 5 years, it is necessary to investigate the change of properties of the material over time. In this study, thermal aging of epoxy matrix/high modulus carbon fiber composite materials are accelerated to predict the long term creep property. Specimens are tested at various temperatures of 100~140°C with dynamic mechanical analysis to obtain creep compliances that are functions of time and temperature. Using Time Temperature Superposition method, creep compliance curves at each temperature are shifted to the reference temperature by shift factor and a master curve is generated at the reference temperature. This information is useful to predict the long term thermal aging of high modulus composite material for spacecraft application.

  9. Repeated superovulation increases the risk of osteoporosis and cardiovascular diseases by accelerating ovarian aging in mice.

    Science.gov (United States)

    Zhang, Jinjin; Lai, Zhiwen; Shi, Liangyan; Tian, Yong; Luo, Aiyue; Xu, Zheyuan; Ma, Xiangyi; Wang, Shixuan

    2018-05-22

    Superovulation procedures and assisted reproductive technologies have been widely used to treat couples who have infertility problems. Although generally safe, the superovulation procedures are associated with a series of complications, such as ovarian hyper-stimulation syndrome, thromboembolism, and adnexal torsion. The role of long-term repeated superovulation in ovarian aging and especially in associated disorders such as osteoporosis and cardiovascular diseases is still unclear. In this study, we sought to determine if repeated superovulation by ten cycles of treatment with pregnant mare serum gonadotropin/human chorionic gonadotropin could affect ovarian reserve, ovarian function, bone density and heart function. Ovarian reserve and function were reflected by the size of the primordial follicle pool, anti-Mullerian hormone expressions, hormone levels and fertility status. Furthermore, we examined bone density and heart function by microCT and cardiovascular ultrasonography, respectively. After repeated superovulation, the size of the primordial follicle pool and the expression of anti-mullerian hormone decreased, along with the concentrations of estrogen and progesterone. Mice exposed to repeated superovulation showed an obvious decrease in fertility and fecundity. Furthermore, both bone density and heart ejection fraction significantly decreased. These results suggest that repeated superovulation may increase the risk of osteoporosis and cardiovascular diseases by accelerating ovarian aging.

  10. Accelerated aging tests of radiation damaged lasers and photodiodes for the CMS tracker optical links

    CERN Document Server

    Gill, K; Batten, J; Cervelli, G; Grabit, R; Jensen, F; Troska, Jan K; Vasey, F

    1999-01-01

    The combined effects of radiation damage and accelerated ageing in COTS lasers and p-i-n photodiodes are presented. Large numbers of these devices are employed in future High Energy Physics experiments and it is vital that these devices are confirmed to be sufficiently robust in terms of both radiation resistance and reliability. Forty 1310 nm InGaAsP edge-emitting lasers (20 irradiated) and 30 InGaAs p- i-n photodiodes (19 irradiated) were aged for 4000 hours at 80 degrees C with periodic measurements made of laser threshold and efficiency, in addition to p-i-n leakage current and photocurrent. There were no sudden failures and there was very little wearout- related degradation in either unirradiated or irradiated sample groups. The results suggest that the tested devices have a sufficiently long lifetime to operate for at least 10 years inside the Compact Muon Solenoid experiment despite being exposed to a harsh radiation environment. (13 refs).

  11. Effect of artificial aging on the microstructure of weldment on API 5L X-52 steel pipe

    International Nuclear Information System (INIS)

    Vargas-Arista, B.; Hallen, J.M.; Albiter, A.

    2007-01-01

    The effects of artificial aging on the microstructure in the weldment of an API 5L X-52 steel pipe were studied. Aging was performed at 250 deg. C over a period of 1000 h and values were recorded at every 100 h intervals. Transmission electron microscopy observations showed precipitation strengthening from nearly circular Nb-C containing nanoparticles for the base metal and heat affected zone, and cementite for the weld metal. The largest amount of precipitation in the weldment zone was obtained at 500 h, due to peak-aging, which showed the highest particle density. The weld metal was more susceptible to aging, exhibiting the highest increase in precipitation at 500 h, followed by the heat affected zone. After 500 h, the deterioration in the microstructure was caused by the coarsening of particles due to over-aging. The base metal showed the larger increment in particle size after 900 h of aging accompanied by a bigger decrease in fine particles than in the weld metal

  12. Proposed research on class I components to test a general approach to accelerated aging under combined stress environments

    International Nuclear Information System (INIS)

    Gillen, K.T.; Salazar, E.A.; Frank, C.W.

    1977-04-01

    This report summarizes research on the aging of Class I components in environments representative of nuclear power plants. It discusses Class IE equipment used in nuclear power plants, typical environments encountered by Class IE components, and aging techniques used to qualify this equipment. General discussions of radiation chemistry of polymers and accelerated aging techniques are also included. Based on the inadequacies of present aging techniques for Class IE equipment, a proposal for an experimental program on electrical cables is presented. One of the main purposes of the proposed work is to obtain relevant data in two areas of particular concern--the effect of radiation dose rate on polymer degradation, and the importance of synergism for combined thermal and radiation environments. A new model that allows combined environment accelerated aging to be carried out is introduced, and it is shown how the experimental data to be generated can be used to test this model

  13. Non-invasive prediction of bloodstain age using the principal component and a back propagation artificial neural network

    Science.gov (United States)

    Sun, Huimin; Meng, Yaoyong; Zhang, Pingli; Li, Yajing; Li, Nan; Li, Caiyun; Guo, Zhiyou

    2017-09-01

    The age determination of bloodstains is an important and immediate challenge for forensic science. No reliable methods are currently available for estimating the age of bloodstains. Here we report a method for determining the age of bloodstains at different storage temperatures. Bloodstains were stored at 37 °C, 25 °C, 4 °C, and  -20 °C for 80 d. Bloodstains were measured using Raman spectroscopy at various time points. The principal component and a back propagation artificial neural network model were then established for estimating the age of the bloodstains. The results were ideal; the square of correlation coefficient was up to 0.99 (R 2  >  0.99) and the root mean square error of the prediction at lowest reached 55.9829 h. This method is real-time, non-invasive, non-destructive and highly efficiency. It may well prove that Raman spectroscopy is a promising tool for the estimation of the age of bloodstains.

  14. Cannabis exposure as an interactive cardiovascular risk factor and accelerant of organismal ageing: a longitudinal study.

    Science.gov (United States)

    Reece, Albert Stuart; Norman, Amanda; Hulse, Gary Kenneth

    2016-11-07

    Many reports exist of the cardiovascular toxicity of smoked cannabis but none of arterial stiffness measures or vascular age (VA). In view of its diverse toxicology, the possibility that cannabis-exposed patients may be ageing more quickly requires investigation. Cross-sectional and longitudinal, observational. Prospective. Single primary care addiction clinic in Brisbane, Australia. 11 cannabis-only smokers, 504 tobacco-only smokers, 114 tobacco and cannabis smokers and 534 non-smokers. known cardiovascular disease or therapy or acute exposure to alcohol, amphetamine, heroin or methadone. Radial arterial pulse wave tonometry (AtCor, SphygmoCor, Sydney) performed opportunistically and sequentially on patients between 2006 and 2011. Algorithmically calculated VA. other central haemodynamic variables. Differences between group chronological ages (CA, 30.47±0.48 to 40.36±2.44, mean±SEM) were controlled with linear regression. Between-group sex differences were controlled by single-sex analysis. Mean cannabis exposure among patients was 37.67±7.16 g-years. In regression models controlling for CA, Body Mass Index (BMI), time and inhalant group, the effect of cannabis use on VA was significant in males (p=0.0156) and females (p=0.0084). The effect size in males was 11.84%. A dose-response relationship was demonstrated with lifetime exposure (pcannabis was robust to adjustment and was unrelated to its acute effects. Significant power interactions between cannabis exposure and the square and cube of CA were demonstrated (from pCannabis is an interactive cardiovascular risk factor (additional to tobacco and opioids), shows a prominent dose-response effect and is robust to adjustment. Cannabis use is associated with an acceleration of the cardiovascular age, which is a powerful surrogate for the organismal-biological age. This likely underlies and bi-directionally interacts with its diverse toxicological profile and is of considerable public health and regulatory

  15. Effect of Artificial Aging Protocols on Surface Gloss of Resin Composites.

    Science.gov (United States)

    Rocha, Rafael Santos; Oliveira, Amanda Carvalho; Caneppele, Taciana Marco Ferraz; Bresciani, Eduardo

    2017-01-01

    The purpose of this study was to evaluate the effect of aging protocols on surface gloss of composites. Cylindrical resin composite specimens (6 mm in diameter, 1 mm thick) were fabricated and divided into three groups ( N = 60): microfilled (MiFi), nanohybrid (NaHy), and nanofilled (NaFi). Specimens were distributed into four aging subgroups: thermocycling (5° to 55°C, 15,000 cycles); ethanol immersion (15 days); brushing (10,750 cycles); and light aging (216 h). Surface gloss readings (Novo-Curve, Rhopoint TM, England) were performed at baseline (R0) and after every one-third of aging protocols (R1 to R3). Data were submitted to one-way repeated measures ANOVA and Tukey's test (5%). Overall, surface gloss alterations were detected over time ( p aging, gloss was reduced after R1 and R2 for MiFi and NaFi, while a reduction only after R1 was detected for NaHy. The studied aging protocols affect surface gloss differently, being material and aging therapy dependent. In general, the surface gloss is reduced with aging.

  16. Mechanical stiffness of TMJ condylar cartilage increases after artificial aging by ribose

    NARCIS (Netherlands)

    Mirahmadi, F.; Koolstra, J.H.; Lobbezoo, F.; van Lenthe, G.H.; Ghazanfari, S.; Snabel, J.; Stoop, R.; Everts, V.

    2018-01-01

    Objective: Aging is accompanied by a series of changes in mature tissues that influence their properties and functions. Collagen, as one of the main extracellular components of cartilage, becomes highly crosslinked during aging. In this study, the aim was to examine whether a correlation exists

  17. Vascular aging processes accelerate following a cubic kinetic: pulse wave velocity as an objective counterpart that time, as we age, goes by faster

    Directory of Open Access Journals (Sweden)

    Gabutti L

    2018-02-01

    Full Text Available Luca Gabutti, Rosaria Del Giorno Department of Internal Medicine and Nephrology, Bellinzona Regional Hospital, Bellinzona, SwitzerlandArterial stiffness is a marker of vascular aging and is considered to be the most reliable parameter expressing, like an integral in mathematics, the cumulative consequences, on the vascular wall, of degenerative and adaptive changes occurring throughout life.1 The efficiency of the reparative processes, the cardiovascular risk factors (CVRF, and early life and genetic determinants, all play a relevant role.1 Among CVRF, the acceleration in arterial stiffness progression related to age is mainly influenced by hypertension.1 A pathological acceleration translates into the concept of early vascular aging, a concept that can be quantified calculating the gap between the subject’s chronological (estimated on the basis of the epidemiological data obtained in the normal population and effective vascular age.2 Data of subpopulations without active risk factors for accelerated vascular aging can be found mainly in three large epidemiological studies, performed respectively in Portugal,3 Argentina,4 and seven different European countries (Belgium, Czech Republic, France, Greece, Italy, the Netherlands, and UK gathered in a collaborative investigation.5 Those doing this secondary analysis were aware of the limitation related to the use of cross-sectional data to extrapolate longitudinal changes, and their aims were combining the abovementioned epidemiological data concerning the normal population to calculate with the highest possible accuracy 1 the age-related increase in acceleration of the pulse wave velocity (PWV and to estimate both 2 the age-specific relative amount of time equivalent to that necessary to progress 1 year in vascular age at 20, and 3 the cumulative relative age calculated in year equivalents. 

  18. Quantitative Proteomic Analysis of Wheat Seeds during Artificial Ageing and Priming Using the Isobaric Tandem Mass Tag Labeling.

    Directory of Open Access Journals (Sweden)

    Yangyong Lv

    Full Text Available Wheat (Triticum aestivum L. is an important crop worldwide. The physiological deterioration of seeds during storage and seed priming is closely associated with germination, and thus contributes to plant growth and subsequent grain yields. In this study, wheat seeds during different stages of artificial ageing (45°C; 50% relative humidity; 98%, 50%, 20%, and 1% Germination rates and priming (hydro-priming treatment were subjected to proteomics analysis through a proteomic approach based on the isobaric tandem mass tag labeling. A total of 162 differentially expressed proteins (DEPs mainly involved in metabolism, energy supply, and defense/stress responses, were identified during artificial ageing and thus validated previous physiological and biochemical studies. These DEPs indicated that the inability to protect against ageing leads to the incremental decomposition of the stored substance, impairment of metabolism and energy supply, and ultimately resulted in seed deterioration. Kyoto Encyclopedia of Genes and Genomes (KEGG analysis revealed that the up-regulated proteins involved in seed ageing were mainly enriched in ribosome, whereas the down-regulated proteins were mainly accumulated in energy supply (starch and sucrose metabolism and stress defense (ascorbate and aldarate metabolism. Proteins, including hemoglobin 1, oleosin, agglutinin, and non-specific lipid-transfer proteins, were first identified in aged seeds and might be regarded as new markers of seed deterioration. Of the identified proteins, 531 DEPs were recognized during seed priming compared with unprimed seeds. In contrast to the up-regulated DEPs in seed ageing, several up-regulated DEPs in priming were involved in energy supply (tricarboxylic acid cycle, glycolysis, and fatty acid oxidation, anabolism (amino acids, and fatty acid synthesis, and cell growth/division. KEGG and protein-protein interaction analysis indicated that the up-regulated proteins in seed priming were

  19. Application of rapid artificial cardiac pacing in thoracic endovascular aortic repair in aged patients

    Directory of Open Access Journals (Sweden)

    Chen J

    2013-12-01

    Full Text Available Jun Chen,1,* Wenhui Huang,2,* Songyuan Luo,2,* Dahao Yang,1 Zhengrong Xu,1 Jianfang Luo21Department of Angiocardiopathy, Affiliated Baoan Hospital of Southern Medical University, Shenzhen City, People's Republic of China; 2Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, People's Republic of China*These authors contributed equally to this workObjective: To compare the safety, efficacy, and impact on stent graft positioning between rapid artificial cardiac pacing (RACP, induced hypotension and sodium nitroprusside (SNP induced hypotension during thoracic endovascular aortic repair (TEVAR for Stanford B aortic dissection.Methods: One hundred and sixty-eight patients, who were diagnosed with Stanford B aortic dissection and who underwent selective TEVAR in Guangdong General Hospital and the People's Hospital of Baoan District, Shenzhen, People's Republic of China, were enrolled in this study. Patients were randomly divided into a RACP group (n=77 and a SNP group (n=91. During localization and deployment of the stent graft, hypotension was induced by RACP or intravenous SNP, according to randomization. Hemodynamics, landing precision (deviation from planned placement site, duration of procedure, renal function, neurocognitive function, and incidence of endoleaks and paraplegia/hemiplegia were compared. Except for methods of inducing hypotension, TEVAR was performed according to the same protocol in each group.Results: RACP was successfully performed in all patients assigned to the RACP group. Compared with the SNP group, blood pressure was significantly lower (43±5 versus 81±6 mmHg, P=0.003 and the restoration time of blood pressure and the operation duration were significantly shorter (7±2 versus 451±87 seconds, P<0.001; 87±15 versus 106±18 minutes, P<0.001, respectively in the RACP group. Stent graft localization/deployment was more precise in the RACP

  20. Bio-Spectroscopic Imaging Provides Evidence of Hippocampal Zn Deficiency and Decreased Lipid Unsaturation in an Accelerated Ageing Mouse Model.

    Science.gov (United States)

    Fimognari, Nicholas; Hollings, Ashley; Lam, Virginie; Tidy, Rebecca J; Kewish, Cameron M; Albrecht, Matthew A; Takechi, Ryu; Mamo, John C L; Hackett, Mark J

    2018-06-14

    Western society is facing a health epidemic due to the increasing incidence of dementia in ageing populations, and there are still few effective diagnostic methods, minimal treatment options, and no cure. Ageing is the greatest risk factor for memory loss that occurs during the natural ageing process, as well as being the greatest risk factor for neurodegenerative disease such as Alzheimer's disease. Therefore, greater understanding of the biochemical pathways that drive a healthy ageing brain towards dementia (pathological ageing or Alzheimer's disease), is required to accelerate the development of improved diagnostics and therapies. Unfortunately, many animal models of dementia model chronic amyloid precursor protein over-expression, which although highly relevant to mechanisms of amyloidosis and familial Alzheimer's disease, does not model well dementia during the natural ageing process. A promising animal model reported to model mechanisms of accelerated natural ageing and memory impairments, is the senescence accelerated murine prone strain 8 (SAMP8), which has been adopted by many research group to study the biochemical transitions that occur during brain ageing. A limitation to traditional methods of biochemical characterisation is that many important biochemical and elemental markers (lipid saturation, lactate, transition metals) cannot be imaged at meso- or micro-spatial resolution. Therefore, in this investigation we report the first multi-modal biospectroscopic characterisation of the SAMP8 model, and have identified important biochemical and elemental alterations, and co-localisations, between 4 month old SAMP8 mice and the relevant control (SAMR1) mice. Specifically, we demonstrate direct evidence of altered metabolism and disturbed lipid homeostasis within corpus callosum white matter, in addition to localised hippocampal metal deficiencies, in the accelerated ageing phenotype. Such findings have important implication for future research aimed at

  1. The effect of the accelerated aging on the mechanical properties of the PMMA denture base materials modified with itaconates

    Directory of Open Access Journals (Sweden)

    Spasojević Pavle M.

    2011-01-01

    Full Text Available This study evaluated the effect of accelerated ageing on the tensile strength, elongation at break, hardness and Charpy impact strength in commercial PMMA denture base material modified with di-methyl itaconate (DMI and di-n-butyl itaconate (DBI. The samples were prepared by modifying commercial formulation by addition of itaconates in the amounts of 2.5, 5, 7.5 and 10% by weight. After polymerization samples were characterized by FT-IR and DSC analysis while residual monomer content was determined by HPLC-UV. Accelerated ageing was performed at 70°C in water for periods of 7, 15 and 30 days. Tensile measurements were performed using Instron testing machine while the hardness of the polymerized samples was measured by Shore D method. The addition of itaconate significantly reduces the residual MMA. Even at the small amounts of added itaconates (2.5% the residual MMA content was reduced by 50%. The increase of itaconate content in the system leads to the decrease of residual MMA. It has been found that the addition of di-n-alkyl itaconates decreases the tensile strength, hardness and Charpy impact strength and increases elongation at break. Samples modified with DMI had higher values of tensile strength, hardness and Charpy impact strength compared to the ones modified with DBI. This is explained by the fact that DBI has longer side chain compared to DMI. After accelerated ageing during a 30 days period the tensile strength decreased for all the investigated samples. The addition of DMI had no effect on the material ageing and the values for the tensile strength of all of the investigated samples decreased around 20%, while for the samples modified with DBI, the increase of the amount of DBI in the polymerized material leads to the higher decrease of the tensile strength after the complete accelerated ageing period od 30 days, aulthough after the first seven days of the accelerated ageing the values of hardness have increased for all of the

  2. Effect of Artificial Aging Protocols on Surface Gloss of Resin Composites

    OpenAIRE

    Rocha, Rafael Santos; Oliveira, Amanda Carvalho; Caneppele, Taciana Marco Ferraz; Bresciani, Eduardo

    2017-01-01

    The purpose of this study was to evaluate the effect of aging protocols on surface gloss of composites. Cylindrical resin composite specimens (6?mm in diameter, 1?mm thick) were fabricated and divided into three groups (N = 60): microfilled (MiFi), nanohybrid (NaHy), and nanofilled (NaFi). Specimens were distributed into four aging subgroups: thermocycling (5? to 55?C, 15,000 cycles); ethanol immersion (15 days); brushing (10,750 cycles); and light aging (216?h). Surface gloss readings (Novo-...

  3. Accelerated Aging Experiments for Prognostics of Damage Growth in Composite Materials

    Science.gov (United States)

    Saxena, Abhinav; Goebel, Kai Frank; Larrosa, Cecilia C.; Janapati, Vishnuvardhan; Roy, Surajit; Chang, Fu-Kuo

    2011-01-01

    Composite structures are gaining importance for use in the aerospace industry. Compared to metallic structures their behavior is less well understood. This lack of understanding may pose constraints on their use. One possible way to deal with some of the risks associated with potential failure is to perform in-situ monitoring to detect precursors of failures. Prognostic algorithms can be used to predict impending failures. They require large amounts of training data to build and tune damage model for making useful predictions. One of the key aspects is to get confirmatory feedback from data as damage progresses. These kinds of data are rarely available from actual systems. The next possible resource to collect such data is an accelerated aging platform. To that end this paper describes a fatigue cycling experiment with the goal to stress carbon-carbon composite coupons with various layups. Piezoelectric disc sensors were used to periodically interrogate the system. Analysis showed distinct differences in the signatures of growing failures between data collected at conditions. Periodic X-radiographs were taken to assess the damage ground truth. Results after signal processing showed clear trends of damage growth that were correlated to damage assessed from the X-ray images.

  4. Evaluation of stone durability using a combination of ultrasound, mechanical and accelerated aging tests

    International Nuclear Information System (INIS)

    Molina, E; Cultrone, G; Sebastián, E; Alonso, F J

    2013-01-01

    The durability of a rock when exposed to decay agents is an important criterion when assessing its quality as a building material. Our study focuses on six varieties of natural stone (two limestones, one dolostone, one travertine and two sandstones) that are widely used in both new and historical buildings. In order to assess their quality, we measured and characterized their dynamic elastic properties using ultrasounds, we measured their compressive strength using the uniaxial compression test and we evaluated their durability by means of accelerated aging tests (freeze-thaw and salt crystallization). In order to get a full picture of the decay suffered by the different stones, we determined the composition and amount of the clay fraction of the six stones. We also observed small fragments subjected to the salt crystallization test under an environmental scanning electron microscope to study any textural change and measured the changes of colour on the surface with a spectrophotometer. Finally, we analysed the pore system of the stones before and after their deterioration using mercury injection porosimetry. We then compared the results for the different stones and found that dolostone obtained the best results, while the two limestones proved to be the least durable and had the lowest compressive strength. (paper)

  5. Coffee Silverskin Extract Protects against Accelerated Aging Caused by Oxidative Agents

    Directory of Open Access Journals (Sweden)

    Amaia Iriondo-DeHond

    2016-06-01

    Full Text Available Nowadays, coffee beans are almost exclusively used for the preparation of the beverage. The sustainability of coffee production can be achieved introducing new applications for the valorization of coffee by-products. Coffee silverskin is the by-product generated during roasting, and because of its powerful antioxidant capacity, coffee silverskin aqueous extract (CSE may be used for other applications, such as antiaging cosmetics and dermaceutics. This study aims to contribute to the coffee sector’s sustainability through the application of CSE to preserve skin health. Preclinical data regarding the antiaging properties of CSE employing human keratinocytes and Caenorhabditis elegans are collected during the present study. Accelerated aging was induced by tert-butyl hydroperoxide (t-BOOH in HaCaT cells and by ultraviolet radiation C (UVC in C. elegans. Results suggest that the tested concentrations of coffee extracts were not cytotoxic, and CSE 1 mg/mL gave resistance to skin cells when oxidative damage was induced by t-BOOH. On the other hand, nematodes treated with CSE (1 mg/mL showed a significant increased longevity compared to those cultured on a standard diet. In conclusion, our results support the antiaging properties of the CSE and its great potential for improving skin health due to its antioxidant character associated with phenols among other bioactive compounds present in the botanical material.

  6. Sox4 Links Tumor Suppression to Accelerated Aging in Mice by Modulating Stem Cell Activation

    Directory of Open Access Journals (Sweden)

    Miguel Foronda

    2014-07-01

    Full Text Available Sox4 expression is restricted in mammals to embryonic structures and some adult tissues, such as lymphoid organs, pancreas, intestine, and skin. During embryogenesis, Sox4 regulates mesenchymal and neural progenitor survival, as well as lymphocyte and myeloid differentiation, and contributes to pancreas, bone, and heart development. Aberrant Sox4 expression is linked to malignant transformation and metastasis in several types of cancer. To understand the role of Sox4 in the adult organism, we first generated mice with reduced whole-body Sox4 expression. These mice display accelerated aging and reduced cancer incidence. To specifically address a role for Sox4 in adult stem cells, we conditionally deleted Sox4 (Sox4cKO in stratified epithelia. Sox4cKO mice show increased skin stem cell quiescence and resistance to chemical carcinogenesis concomitantly with downregulation of cell cycle, DNA repair, and activated hair follicle stem cell pathways. Altogether, these findings highlight the importance of Sox4 in regulating adult tissue homeostasis and cancer.

  7. Characterization of constrained aged Ni Ti strips for using in artificial muscle actuators

    International Nuclear Information System (INIS)

    Hassanzadeh Nemati, N.; Sadrnezhaad, S. K.

    2011-01-01

    Marvelous bending/straightening effects of two-way shape memory alloy help their employment in design and manufacturing of new medical appliances. Constrained ageing with bending load scheme can induce two-way shape memory effect. Scanning electron microscopic analysis, electrical resistivity measurement and differential scanning calorimetry are employed to determine the property change due to flat strip constrained aging. Results show that flat-annealing prior to the aging shifts Ni Ti transformations temperatures to higher values. Super elastic behavior of the as-received/flat-annealed/aged samples with more adequate transition temperatures due to biological tissue replacement is studied by three-point flexural tests. Results show that curing changes the transition points of the Ni Ti strips. These changes affect the shape memory behavior of the Ni Ti strips embedded within the biocompatible flexible composite segments.

  8. Effect of Artificial Aging Protocols on Surface Gloss of Resin Composites

    Directory of Open Access Journals (Sweden)

    Rafael Santos Rocha

    2017-01-01

    Full Text Available The purpose of this study was to evaluate the effect of aging protocols on surface gloss of composites. Cylindrical resin composite specimens (6 mm in diameter, 1 mm thick were fabricated and divided into three groups (N=60: microfilled (MiFi, nanohybrid (NaHy, and nanofilled (NaFi. Specimens were distributed into four aging subgroups: thermocycling (5° to 55°C, 15,000 cycles; ethanol immersion (15 days; brushing (10,750 cycles; and light aging (216 h. Surface gloss readings (Novo-Curve, Rhopoint TM, England were performed at baseline (R0 and after every one-third of aging protocols (R1 to R3. Data were submitted to one-way repeated measures ANOVA and Tukey’s test (5%. Overall, surface gloss alterations were detected over time (p<0.001. Thermocycling reduced surface gloss, except for NaHy. Ethanol immersion resulted in surface gloss reduction after R1 for MiFi and NaFi, while reduction after R1 and R2 was detected for NaHy. For brushing, gloss reduction was detected after R1 and R3 for all composites. For light aging, gloss was reduced after R1 and R2 for MiFi and NaFi, while a reduction only after R1 was detected for NaHy. The studied aging protocols affect surface gloss differently, being material and aging therapy dependent. In general, the surface gloss is reduced with aging.

  9. DNA methylation-based forensic age prediction using artificial neural networks and next generation sequencing.

    Science.gov (United States)

    Vidaki, Athina; Ballard, David; Aliferi, Anastasia; Miller, Thomas H; Barron, Leon P; Syndercombe Court, Denise

    2017-05-01

    The ability to estimate the age of the donor from recovered biological material at a crime scene can be of substantial value in forensic investigations. Aging can be complex and is associated with various molecular modifications in cells that accumulate over a person's lifetime including epigenetic patterns. The aim of this study was to use age-specific DNA methylation patterns to generate an accurate model for the prediction of chronological age using data from whole blood. In total, 45 age-associated CpG sites were selected based on their reported age coefficients in a previous extensive study and investigated using publicly available methylation data obtained from 1156 whole blood samples (aged 2-90 years) analysed with Illumina's genome-wide methylation platforms (27K/450K). Applying stepwise regression for variable selection, 23 of these CpG sites were identified that could significantly contribute to age prediction modelling and multiple regression analysis carried out with these markers provided an accurate prediction of age (R 2 =0.92, mean absolute error (MAE)=4.6 years). However, applying machine learning, and more specifically a generalised regression neural network model, the age prediction significantly improved (R 2 =0.96) with a MAE=3.3 years for the training set and 4.4 years for a blind test set of 231 cases. The machine learning approach used 16 CpG sites, located in 16 different genomic regions, with the top 3 predictors of age belonged to the genes NHLRC1, SCGN and CSNK1D. The proposed model was further tested using independent cohorts of 53 monozygotic twins (MAE=7.1 years) and a cohort of 1011 disease state individuals (MAE=7.2 years). Furthermore, we highlighted the age markers' potential applicability in samples other than blood by predicting age with similar accuracy in 265 saliva samples (R 2 =0.96) with a MAE=3.2 years (training set) and 4.0 years (blind test). In an attempt to create a sensitive and accurate age prediction test, a next

  10. [Autonomic regulation at emotional stress under hypoxic conditions in the elderly with physiological and accelerated aging: effect of hypoxic training].

    Science.gov (United States)

    Os'mak, E D; Asanov, É O

    2014-01-01

    The effect of hypoxic training on autonomic regulation in psycho-emotional stress conditions in hypoxic conditions in older people with physiological (25 people) and accelerated (28 people) aging respiratory system. It is shown that hypoxic training leads to an increase in vagal activity indicators (HF) and reduced simpatovagal index (LF/HF), have a normalizing effect on the autonomic balance during stress loads in older people with different types of aging respiratory system.

  11. Analysis of Strengthening Mechanisms in an Artificially Aged Ultrafine Grain 6061 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Rezaei

    2017-12-01

    Full Text Available The current study adopted a quantitative approach to investigating the mechanical properties, and their relationship to the microstructural features, of precipitation-strengthened 6061 aluminum alloy processed through accumulative roll bonding (ARB and aging heat treatment.  To serve this purpose, the contributions of different strengthening mechanisms including grain refinement, precipitation, dislocation and solid-solution strengthening to the yield strength of five-cycle ARB samples processed under pre-aged (ARBed and aged (ARBed+Aged conditions were examined and compared. Microstructural characterizations were performed on the samples through the transmission electron microscope (TEM and X-ray diffraction (XRD. Also, the mechanical properties of the samples were investigated through the tensile test. The obtained results showed that an equiaxed ultrafine grain structure with nano-sized precipitates was created in the both ARBed and ARBed+Aged samples. The grain refinement was the predominant strengthening mechanism which was estimated to contribute 151 and 226 MPa to the ARBed and ARBed+Aged samples, respectively, while the dislocation and Orowan strengthening mechanisms were ranked second with regard to their contributions to the ARBed and ARBed+Aged samples, respectively. The overall yield strength, calculated through the root mean square summation method, was found to be in good agreement with the experimentally determined yield strength. It was also found that the presence of non-shearable precipitates, which interfered with the movement of the dislocations, would be effective for the simultaneous improvement of the strength and ductility of the ARBed+Agedsample .

  12. Buyid Silk and the Tale of Bibi Shahrbanu: Identification of Biomarkers of Artificial Aging (Forgery) of Silk.

    Science.gov (United States)

    Moini, Mehdi; Rollman, Christopher M

    2017-10-03

    Buyid silk forgery is one of the most famous silk forgeries in the world. In 1924-1925, excavation of the Bibi Shahrbanu site in Iran unearthed several silk textiles. The silks were thought to be of the Buyid period (934-1062 BCE) of the Persian Empire and have since been known as the "Buyid silks". In the 1930s, more silk appeared and was reported as being from the Buyid period as well. Controversy over the authenticity of these silks escalated after the purchase of the silks by museums throughout the world. Extensive investigations of several of these silks have been conducted over the years with respect to iconography, weaving patterns, dyes/mordant, style, and even radiocarbon dating. It was found that most of the silks are not from Buyid period. To test the authenticity of these silk fabrics, the recently developed silk dating technique using amino acid racemization (AAR) in conjunction with capillary electrophoresis mass spectrometry was applied to 13 Buyid silk specimens from the Textile Museum collections. Among these silk specimens, the AAR ratios of only one specimen were consistent with authentic silk fabrics collected from various museums. In addition, the aspartic acid racemization ratio of this specimen was also consistent with its 14 C dating. The other "Buyid silks" showed excessive levels of amino acid racemization not only for aspartic acid, but also for phenylalanine and tyrosine, inconsistent with racemization rates of these amino acids in authentic historical silk fabrics. Treatment of modern silk with a base at different pH and temperature reproduced the AAR pattern of the Buyid silks, implying that chemical treatment with a base at relatively high temperatures was perhaps the method used to artificially age these fabrics. The results imply that the racemization ratios of aspartic acid, phenylalanine, and tyrosine can be used as biomarkers for identification of naturally versus artificially aged silk.

  13. Effects of accelerated aging upon the lipid composition of seeds from two soft wheat varieties from Morocco

    Energy Technology Data Exchange (ETDEWEB)

    Ouzouline, M.; Tahani, N.; Demandre, C.; El Amrani, A.; Benhassaine-Kesri, G.; Serghini Caid, H.

    2009-07-01

    The lipid composition of the seeds from two soft wheat varieties (Triticum aestivum, cv. Marchouche and Mahdia) were analyzed before and after accelerated aging. Eight days of accelerated aging resulted in a total inhibition of seed germ inability as well as a decrease in their total and especially unsaturated fatty acid contents. Oleic and linoleic acid contents decreased particularly in the phosphatidylcholine of the seeds from both varieties. The proportion of polar lipids also decreased after aging as compared to neutral lipids: a 5.8% and 7.2% decrease in polar lipids was e observed in Mahdia and Marchouche cultivars, respectively. In the neutral lipids of the seeds from the Marchouche variety, the percentage of free fatty acids increased whereas the triacylglycerols decreased. After aging, the fatty acid compositions of all lipid classes were modified in the same manner as total fatty acid compositions. Among polar lipids, phospholipid proportions were particularly small, especially the phosphatidylcholine percentages with an 18.1% and 19.1% decrease in Mahdia and Marchouche varieties, respectively. In contrast, MGDG percentages increased, especially in the seeds from the Marchouche variety. A 15.5% increase was noticed when compared with seeds which were not aged. At the same time, the DGDG percentage showed a 16.6% decrease after accelerated aging of the seeds from the Marchouche variety. From these results we concluded that the lipid content decrease observed in seeds after accelerated aging could be linked to a loss in the germination and vigor of wheat seeds. (Author) 38 refs.

  14. Effect of artificial aging on the surface roughness and microhardness of resin-based materials.

    Science.gov (United States)

    Santos, M Jacinta M C; Rêgo, Heleine Maria Chagas; Mukhopadhyay, Anuradha; El Najjar, Mai; Santos, Gildo C

    2016-01-01

    This study sought to verify the effects of aging on the surface roughness (Ra) and microhardness (Knoop hardness number [KHN]) of resin-based restorative materials protected with a surface sealer. Disc specimens of 2 resin-modified glass ionomers (RMGIs) and 1 composite resin (CR) were fabricated in a metal mold. Specimens of each material were divided into 1 group that was covered with surface sealer and 1 group that was not. Both groups of each material were then subdivided according to whether they were stored (aged) in cola or distilled water. Surface roughness and KHN values were obtained from each specimen before and after storage. After aging of the specimens, significantly higher Ra values were observed in the 2 RMGIs when they were not covered with a surface sealer, while the CR was not affected. The KHN values varied by materials and storage conditions (with and without a surface sealer). All the groups with a surface sealer exhibited increased Ra values after aging.

  15. Effect of artificial aging on polymeric surge arresters and polymer insulators for electricity distribution networks

    Directory of Open Access Journals (Sweden)

    Carlos A. Ferreira

    2011-01-01

    Full Text Available A study was conducted to evaluate new and laboratory-aged samples of surge arresters and anchorage polymeric insulators, for 12 and 24 kV networks, which are used by the Rio Grande Energia (RGE. Power Utility Polymeric compounds were analyzed by Differential Scanning Calorimetry (DSC, Thermogravimetric Analysis (TG, Dynamic-Mechanic Analysis (DMA, Fourier Transformed Infrared Spectroscopy (FTIR and Scanning Electronic Microscopy (SEM to verify changes in the insulator properties due to degradation occurred during the experiments. The analyses were carried out before and after 6 months of aging in laboratory devices (weatherometer, 120 °C, salt spray, immersion in water. After the aging experiments, high-voltage electrical tests were also conducted: a radio interference voltage test and, simultaneously, the total and the internal leakage currents were measured to verify the surface degradation of the polymeric material used in the housing. The impulse current test was applied with current values close to 5, 10 and 30 kA, in order to force an internal degradation. Results showed that only surface degradation is detected at the polymer. The main properties of the parts were not affected by the aging. It confirms that polymer insulator and surge arrestor are appropriate for use in electricity distribution networks.

  16. Effect of artificial aging on polymeric surge arresters and polymer insulators for electricity distribution networks

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Carlos A.; Coser, E. [Laboratorio de Materiais Polimericos, Departamento de Engenharia de Materiais, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil)], e-mail: ferreira.carlos@ufrgs.br; Angelini, Joceli M.G. [Departamento de Materiais Eletricos, CPqD, Campinas, SP (Brazil); Rossi, Jose A.D. [Materiais Alta Tensao, CPqD, Campinas, SP (Brazil); Martinez, Manuel L.B. [Departamento de Engenharia Eletrica, UNIFEI, Itajuba, MG (Brazil)

    2011-07-01

    A study was conducted to evaluate new and laboratory-aged samples of surge arresters and anchorage polymeric insulators, for 12 and 24 kV networks, which are used by the Rio Grande Energia (RGE). Power utility polymeric compounds were analyzed by Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TG), Dynamic-Mechanic Analysis (DMA), Fourier Transformed Infrared Spectroscopy (FTIR) and Scanning Electronic Microscopy (SEM) to verify changes in the insulator properties due to degradation occurred during the experiments. The analyses were carried out before and after 6 months of aging in laboratory devices (weather meter, 120 deg C, salt spray, immersion in water). After the aging experiments, high-voltage electrical tests were also conducted: a radio interference voltage test and, simultaneously, the total and the internal leakage currents were measured to verify the surface degradation of the polymeric material used in the housing. The impulse current test was applied with current values close to 5, 10 and 30 k A, in order to force an internal degradation. Results showed that only surface degradation is detected at the polymer. The main properties of the parts were not affected by the aging. It confirms that polymer insulator and surge arrester are appropriate for use in electricity distribution networks. (author)

  17. Effect of heat treatment and artificial ageing on Al-5Mg-2Zn

    CSIR Research Space (South Africa)

    Chauke, Levy

    2017-10-01

    Full Text Available ageing of Al-5Mg-2Zn. The study showed intermetallic phases at the grain boundaries and a melting peak at about 476 °C for the F condition. Solution heat treatment at 440°C for 4 hours dissolved the intermetallic phase thus increasing the melting point...

  18. Effect of dietary, social, and lifestyle determinants of accelerated aging and its common clinical presentation: A survey study.

    Science.gov (United States)

    Samarakoon, S M S; Chandola, H M; Ravishankar, B

    2011-07-01

    Aging is unavoidable and natural phenomenon of life. Modern gerontologists are realizing the fact that aging is a disease, which Ayurveda had accepted as natural disease since long. Rate of aging is determined by one's biological, social, lifestyle, and psychological conditions and adversity of which leads to accelerated form of aging (Akalaja jara or premature aging). The aim of this study is to identify potential factors that may accelerate aging in the context of dietry factors, lifestyle and mental makeup. The 120 diagnosed subjects of premature-ageing of 30-60 years were randomly selected in the survey study. Premature ageing was common among females (75.83%), in 30-40 age group (70%), 86.67% were married, had secondary level of education (36.66%), house-views (61.67%), belongs top middle class (58.33%) and engaged in occupations that dominating physical labour (88.33%). The maximum patients are constipated (60%), had mandagni (80%), vata-kapha prakriti (48.33%), rajasika prakriti (58.33%), madhyama vyayama shakti (73.33%), and madhyama jarana shakti (85.83%). Collectively, 43.33% patients were above normal BMI. The more patients had anushna (38.33%) and vishamasana dietary pattern (25.83%), consumed Lavana (88.33%) and Amla rasa (78.33%) in excess on regular basis. Some patients had addicted to tobacco (11.67%) and beetle chewing (5.83%). The maximum patients had no any exercise (79.17%) and specific hobby (79.17%) in their leisure times. Analyzing Hamilton Anxiety and Depression Rating Scales revealed that 39.80%, 37.86%, 33.98%, 24.27% and 18.44% patients had insomnia, depression, tension, GIT symptoms and anxious mood respectively. These data suggest that certain social, dietary and lifestyle factors contribute towards accelerated ageing among young individuals.

  19. The effect of trace additions of Zn on the precipitation behavior of alloy 8090 during artificial aging

    Science.gov (United States)

    Kilmer, R. J.; Stoner, G. E.

    1991-01-01

    The effect(s) of trace additions of Zn to the artificial aging behavior of alloy 8090 (Al-Li-Cu-Mg-Zr) was investigated in the approximate composition range 0-1 wt-pct Zn. Trace Zn additions were found to delay aging and under equivalent aging treatments (100 hrs at 160 C) the alloy without Zn and the 1.07 wt-pct Zn alloy developed delta-prime-free zones along subgrain boundaries, while the alloys of 0.21 and 0.58 wt-pct Zn did not. DSC analysis indicated that Zn was being incorporated into the delta-prime, shifting it's exotherm to higher temperatures, while having little if any effect on its associated endotherm making it unlikely that it is an artifact of a solvus shift. In the 8090 + 1.07 wt-pct Zn alloy, coarse precipitates were found to reside on subgrain boundaries and EDS indicated that they were rich in Cu and Zn. It was also noted that in the Zn containing 8090 varients, the S prime precipitates were more coarse in size than the baseline 8090.

  20. Poor maternal nutrition and accelerated postnatal growth induces an accelerated aging phenotype and oxidative stress in skeletal muscle of male rats

    Directory of Open Access Journals (Sweden)

    Jane L. Tarry-Adkins

    2016-10-01

    Full Text Available ‘Developmental programming’, which occurs as a consequence of suboptimal in utero and early environments, can be associated with metabolic dysfunction in later life, including an increased incidence of cardiovascular disease and type 2 diabetes, and predisposition of older men to sarcopenia. However, the molecular mechanisms underpinning these associations are poorly understood. Many conditions associated with developmental programming are also known to be associated with the aging process. We therefore utilized our well-established rat model of low birth weight and accelerated postnatal catch-up growth (termed ‘recuperated’ in this study to establish the effects of suboptimal maternal nutrition on age-associated factors in skeletal muscle. We demonstrated accelerated telomere shortening (a robust marker of cellular aging as evidenced by a reduced frequency of long telomeres (48.5-8.6 kb and an increased frequency of short telomeres (4.2-1.3 kb in vastus lateralis muscle from aged recuperated offspring compared to controls. This was associated with increased protein expression of the DNA-damage-repair marker 8-oxoguanine-glycosylase (OGG1 in recuperated offspring. Recuperated animals also demonstrated an oxidative stress phenotype, with decreased citrate synthase activity, increased electron-transport-complex activities of complex I, complex II-III and complex IV (all markers of functional mitochondria, and increased xanthine oxidase (XO, p67phox and nuclear-factor kappa-light-chain-enhancer of activated B-cells (NF-κB. Recuperated offspring also demonstrated increased antioxidant defense capacity, with increased protein expression of manganese superoxide dismutase (MnSOD, copper-zinc superoxide dismutase (CuZnSOD, catalase and heme oxygenase-1 (HO1, all of which are known targets of NF-κB and can be upregulated as a consequence of oxidative stress. Recuperated offspring also had a pro-inflammatory phenotype, as evidenced by

  1. Age estimation of Calliphora (Diptera: Calliphoridae) larvae using cuticular hydrocarbon analysis and Artificial Neural Networks

    OpenAIRE

    Moore, H E; Butcher, J B; Adam, C D; Day, C R; Falko, P D

    2016-01-01

    Cuticular hydrocarbons were extracted daily from the larvae of two closely related blowflies Calliphora vicina and Calliphora vomitoria (Diptera: Calliphoridae). The hydrocarbons were then analysed using Gas Chromatography–Mass Spectrometry (GC–MS), with the aim of observing changes within their chemical profiles in order to determine the larval age. The hydrocarbons were examined daily for each species from 1 day old larvae until pupariation. The results show significant chemical changes occ...

  2. Radiation pre-treatment of seed imparts metabolic stability and quality protection during storage under accelerated aging

    International Nuclear Information System (INIS)

    Sumedha; Singh, Bhupinder; Singhal, R.K.

    2014-01-01

    Quality of seed is known to deteriorate due to unfavoured temperature and relative humidity during accelerated aging. Protecting the seed quality during storage is thus a priority challenge for the seed industry till the seeds end up with the end user. Gamma radiation treatment has been shown to improve source to sink transport of photosynthates during terminal heat stress in cereals. An experiment was conducted to measure seed irradiation induced biochemical changes in groundnut cultivar TG-37A stored under accelerated aging at 45±2 ℃ and 95-100 % humidity for 0, 5, 10, 15, 20 and 40 days to aging. The gamma irradiation doses were control (0), 0.005, 0.025, 0.1, 0.5 and 1.0 kGy. Seed samples were periodically evaluated for oil and fatty acid profile by the soxhlet extraction method and gas chromatography mass spectroscopy respectively. Here alike earlier studies variation in fatty acid profile of seed was used as an indicator of seed health under harsh storage conditions of accelerated aging. In the majority of plant species having oil rich seeds, the lipids that are at risk of auto-oxidation contain oleic (18:1), linoleic (18:2) and linolenic (18:3) fatty acid chain. Degree of unsaturation has a significant influence on degree of degradation. Decreased total lipid content in aged sunflower seeds have been reported. Auto-oxidation of unsaturated fatty acids was noticed, especially for linoleic acid in seed of oil crop after seven years of storage. Our results showed radiation treatment did not cause any significant change in oleic (C18:1), linoleic acids (C18:2) and linolenic (C18:3) acid content of seeds. This shows that gamma radiation essentially slows down the lipid peroxidation which essentially protects membrane permeability and reduces the rate of seed deterioration at high temperature and RH. Radiation treatment imparts metabolic stability in seeds during storage under accelerated aging conditions. (author)

  3. Bond strength of primer/cement systems to zirconia subjected to artificial aging.

    Science.gov (United States)

    Zhao, Li; Jian, Yu-Tao; Wang, Xiao-Dong; Zhao, Ke

    2016-11-01

    Creating reliable and durable adhesion to the nonactive zirconia surface is difficult and has limited zirconia use. The introduction of functional monomers such as 10-methacryloyloxydecyl dihydrogen phosphate (MDP) appears to have enhanced bond strength to zirconia. The purpose of this in vitro study was to evaluate the long-term bond strength of several MDP-containing primer/cement systems to zirconia. Zirconia blocks were divided into 6 groups (n=24) according to the 3 primers/cements to be bonded, as follows: Scotchbond Universal/RelyX Ultimate (SU/RU; consisting of MDP-containing primer/MDP-free cement); Clearfil ceramic primer/Panavia F (CCP/PAN; consisting ofMDP-containing/MDP-containing); and Z-Prime Plus/Duo-Link (ZP/DUO; consisting ofMDP-containing/MDP-free), which were compared with 3 nonprimed groups, RU, PAN, and DUO. After bonding, each group was further divided into 3 subgroups (n=8) according to the level of aging: 24-hour storage in water at 37°C (24H); 30-day storage at 37°C (30D); and 30-day storage at 37°C followed by 3000 thermal cycles (30D/TC). After aging, a shear bond strength test and failure mode analysis were performed. The data were analyzed using 2-way ANOVA (α=.05). After aging, nearly all primer/cement groups presented significantly higher bond strength than the related nonprimed groups for each level of aging (P<.05), except for CCP/PAN versus PAN with 24H (P=.741). SU/RU had the highest bond strength among the groups for all treatments (P<.05), except for CCP/PAN versus SU/RU with 30D/TC (P=.171). Among the nonprimed groups, only RU went through 30D/TC without premature debonding. With 24H and 30D, the failure modes in SU/RU and CCP/PAN were purely mixed, whereas those in the other groups were mainly adhesive, except for RU. The superiority of the initial bond strength in SU/RU may result from some functional components other than MDP. The presence of MDP in the cement did not appear to have a positive effect on long-term bond

  4. Effect of saliva contamination and artificial aging on different primer/cement systems bonded to zirconia.

    Science.gov (United States)

    Pitta, João; Branco, Teresa C; Portugal, Jaime

    2018-05-01

    Saliva contamination has been shown to decrease bonding to zirconia. Adopting a less contamination-sensitive cement system may be an alternative to decontamination. The purpose of this in vitro study was to assess the ability of different primer/cement systems to promote a durable bond to zirconia after saliva contamination. Zirconia blocks (Lava Plus) (N=320) were airborne-particle abraded (50 μm Al 2 O 3 ) and divided into 32 experimental groups (n=10) according to the variables in the study: saliva contamination; primer/cement system (Panavia SA [PSA]; RelyX Unicem 2 [RU2]; Bifix SE [BSE]; Panavia F2.0 [PF2]; Scotchbond Universal + RelyX Ultimate [SBU+RXU]; Futurabond M+ + Bifix QM [FBM+BQM]; All-Bond Universal + Duo-link [ABU+DL]; Z-Prime Plus + Duo-link [ZPP+DL]; and aging period (72 hours; 30 days with 10 000 thermocycles at 5°C to 55°C). After half of the blocks had been contaminated with fresh human saliva for 10 minutes, rinsed with water, and air-dried, each primer/cement was applied. Polymerized composite resin disks were then placed over the cement, and the resin cement was light-polymerized for 20 seconds each at 2 opposite margins. After the aging time, the specimens were tested in shear (1 mm/min). The failure mode was classified as adhesive, cohesive, or mixed. Statistical analysis of the shear bond strength (SBS) data was performed with ANOVA followed by Tukey honest significant difference post hoc tests. Chi-square tests were used to analyze the failure mode data (α=.05). The mean SBS ranged between 4.2 and 34.5 MPa. Shear bond strength was influenced (Pcontamination, aging time). SBU+RXU and FBM+BQM showed a higher mean SBS than those of the other experimental groups (Pcontamination (P>.05). Failure was predominantly classified as adhesive. In general, saliva contamination and aging decreased bonding efficacy. Two systems, combining an application of a universal adhesive and a resin cement (SBU+RXU and FBM+BQM) were not affected by

  5. An artificial intelligence-based structural health monitoring system for aging aircraft

    Science.gov (United States)

    Grady, Joseph E.; Tang, Stanley S.; Chen, K. L.

    1993-01-01

    To reduce operating expenses, airlines are now using the existing fleets of commercial aircraft well beyond their originally anticipated service lives. The repair and maintenance of these 'aging aircraft' has therefore become a critical safety issue, both to the airlines and the Federal Aviation Administration. This paper presents the results of an innovative research program to develop a structural monitoring system that will be used to evaluate the integrity of in-service aerospace structural components. Currently in the final phase of its development, this monitoring system will indicate when repair or maintenance of a damaged structural component is necessary.

  6. Natural and artificial aging response of semisolid metal processed Al–Si–Mg alloy A356

    CSIR Research Space (South Africa)

    Moller, H

    2007-12-01

    Full Text Available aging at 180uC (Table 2). It can be seen from Table 2 that it takes approximately six times longer to reach peak hardness at 160uC compared to at 180uC. The diffusivity of silicon in aluminium is about double that of magnesium in aluminium... in the content of alloying elements. In Al–Mg–Si alloys containing an excess of silicon, the decomposition of the super- saturated solid solution (SSS) is believed to occur as follows7 SSS?(MgzSi)clusters=GP(I)spherical ?b=GP(II)needles?b0rodsz...

  7. Comparative study of the fluorescence intensity of dental composites and human teeth submitted to artificial aging.

    Science.gov (United States)

    Jablonski, Tatiana; Takahashi, Marcos Kenzo; Brum, Rafeal Torres; Rached, Rodrigo Nunes; Souza, Evelise M

    2014-01-01

    The aim of this study was to evaluate quantitatively the fluorescence of resin composites and human teeth, and to determine the stability of fluorescence after aging. Ten specimens were built using a 1 mm thick increment of dentin composite overlapped by a 0.5 mm thick increment of enamel composite. Ten sound human molars were sectioned and silicon carbide-polished to obtain enamel and dentin slabs 1.5 mm in thickness. Fluorescence measurements were carried out by a fluorescence spectrophotometer before and after thermocycling (2000 cycles, 5°C and 55°C). One-way analysis of variance (ANOVA) with repeated measures and Tukey's test were performed at a significance level of 5%. Most of the tested composites showed significant differences in fluorescence both before and after aging (P 0.05), and was the only composite that showed comparable results of fluorescence to the tooth structure before and after thermocycling. With the exception of Filtek Supreme, there were significant reductions in fluorescence intensity for all the tested composites (P < 0.05).

  8. Exercise does not enhance aged bone's impaired response to artificial loading in C57Bl/6 mice.

    Science.gov (United States)

    Meakin, Lee B; Udeh, Chinedu; Galea, Gabriel L; Lanyon, Lance E; Price, Joanna S

    2015-12-01

    Bones adapt their structure to their loading environment and so ensure that they become, and are maintained, sufficiently strong to withstand the loads to which they are habituated. The effectiveness of this process declines with age and bones become fragile fracturing with less force. This effect in humans also occurs in mice which experience age-related bone loss and reduced adaptation to loading. Exercise engenders many systemic and local muscular physiological responses as well as engendering local bone strain. To investigate whether these physiological responses influence bones' adaptive responses to mechanical strain we examined whether a period of treadmill exercise influenced the adaptive response to an associated period of artificial loading in young adult (17-week) and old (19-month) mice. After treadmill acclimatization, mice were exercised for 30 min three times per week for two weeks. Three hours after each exercise period, right tibiae were subjected to 40 cycles of non-invasive axial loading engendering peak strain of 2250 με. In both young and aged mice exercise increased cross-sectional muscle area and serum sclerostin concentration. In young mice it also increased serum IGF1. Exercise did not affect bone's adaptation to loading in any measured parameter in young or aged bone. These data demonstrate that a level of exercise sufficient to cause systemic changes in serum, and adaptive changes in local musculature, has no effect on bone's response to loading 3h later. This study provides no support for the beneficial effects of exercise on bone in the elderly being mediated by systemic or local muscle-derived effects rather than local adaptation to altered mechanical strain. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  9. Acceleration of leukocytes' epigenetic age as an early tumor and sex-specific marker of breast and colorectal cancer.

    Science.gov (United States)

    Durso, Danielle Fernandes; Bacalini, Maria Giulia; Sala, Claudia; Pirazzini, Chiara; Marasco, Elena; Bonafé, Massimiliano; do Valle, Ítalo Faria; Gentilini, Davide; Castellani, Gastone; Faria, Ana Maria Caetano; Franceschi, Claudio; Garagnani, Paolo; Nardini, Christine

    2017-04-04

    Changes in blood epigenetic age have been associated with several pathological conditions and have recently been described to anticipate cancer development. In this work, we analyze a publicly available leukocytes methylation dataset to evaluate the relation between DNA methylation age and the prospective development of specific types of cancer. We calculated DNA methylation age acceleration using five state-of-the-art estimators (three multi-site: Horvath, Hannum, Weidner; and two CpG specific: ELOV2 and FHL2) in a cohort including 845 subjects from the EPIC-Italy project and we compared 424 samples that remained cancer-free over the approximately ten years of follow-up with 235 and 166 subjects who developed breast and colorectal cancer, respectively. We show that the epigenetic age estimated from blood DNA methylation data is statistically significantly associated to future breast and male colorectal cancer development. These results are corroborated by survival analysis that shows significant association between age acceleration and cancer incidence suggesting that the chance of developing age-related diseases may be predicted by circulating epigenetic markers, with a dependence upon tumor type, sex and age estimator. These are encouraging results towards the non-invasive and perspective usage of epigenetic biomarkers.

  10. Effect of accelerated ageing and surface sealing on the permanent deformation of auto-polymerising soft linings.

    Science.gov (United States)

    da Silva, Joaquim; Takahashi, Jessica; Nuňez, Juliana; Consani, Rafael; Mesquita, Marcelo

    2012-09-01

    To compare the effects of different ageing methods on the permanent deformation of two permanent soft liners. The materials selected were auto-polymerising acrylic resin and silicone-based reliners. Sealer coating was also evaluated. Sixty specimens of each reliner were manufactured (12.7 mm diameter and 19 mm length). Specimens were randomly distributed into 12 groups (n = 10) and submitted to one of the accelerated ageing processes. Permanent deformation tests were conducted with a mechanical device described within the American Dental Association specification number 18 with a compressive load of 750 gf applied for 30 s. All data were submitted for statistical analysis. Mann-Whitney test compared the effect of the surface sealer on each material and the permanent deformation of the materials in the same ageing group (p = 0.05). Kruskal-Wallis and Dunn tests compared all ageing groups of each material (p = 0.05). The silicone-based reliner presented a lower permanent deformation than the acrylic resin-based reliner, regardless of the ageing procedure. The surface sealer coating was effective only for the thermocycled silicone group and the accelerated ageing processes affected only the permanent deformation of the acrylic resin-based material. The silicone-based reliner presented superior elastic properties and the thermocycling was more effective in ageing the materials. © 2010 The Gerodontology Society and John Wiley & Sons A/S.

  11. Artificial intelligence and accelerator control

    International Nuclear Information System (INIS)

    Weygand, D.P.

    1987-01-01

    In this paper we review a knowledge-based, domain specific expert system which is under development at Brookhaven National Laboratory to aid in the control of the Heavy Ion Transfer Line (HITL). The expert system is being developed in order to minimize down time after a change of running conditions or at the start of a new run. While the control of HITL is relatively simple compared to a synchrotron, conceptually, many of the problems that are encountered may be extrapolated to more complex machines

  12. Lifestyle-induced metabolic inflexibility and accelerated ageing syndrome: insulin resistance, friend or foe?

    Directory of Open Access Journals (Sweden)

    Bell Jimmy D

    2009-04-01

    that as oxidative stress determines functional longevity, a rather more descriptive term for the metabolic syndrome is the 'lifestyle-induced metabolic inflexibility and accelerated ageing syndrome'. Ultimately, thriftiness is good for us as long as we have hormetic stimuli; unfortunately, mankind is attempting to remove all hormetic (stressful stimuli from his environment.

  13. Human Age Recognition by Electrocardiogram Signal Based on Artificial Neural Network

    Science.gov (United States)

    Dasgupta, Hirak

    2016-12-01

    The objective of this work is to make a neural network function approximation model to detect human age from the electrocardiogram (ECG) signal. The input vectors of the neural network are the Katz fractal dimension of the ECG signal, frequencies in the QRS complex, male or female (represented by numeric constant) and the average of successive R-R peak distance of a particular ECG signal. The QRS complex has been detected by short time Fourier transform algorithm. The successive R peak has been detected by, first cutting the signal into periods by auto-correlation method and then finding the absolute of the highest point in each period. The neural network used in this problem consists of two layers, with Sigmoid neuron in the input and linear neuron in the output layer. The result shows the mean of errors as -0.49, 1.03, 0.79 years and the standard deviation of errors as 1.81, 1.77, 2.70 years during training, cross validation and testing with unknown data sets, respectively.

  14. Influence of surface treatment of yttrium-stabilized tetragonal zirconium oxides and cement type on crown retention after artificial aging.

    Science.gov (United States)

    Karimipour-Saryazdi, Mehdi; Sadid-Zadeh, Ramtin; Givan, Daniel; Burgess, John O; Ramp, Lance C; Liu, Perng-Ru

    2014-05-01

    Information about the influence of zirconia crown surface treatment and cement type on the retention of zirconia crowns is limited. It is unclear whether zirconia crowns require surface treatment to enhance their retention. The purpose of this in vitro study was to evaluate the effect of surface treatment on the retention of zirconia crowns cemented with 3 different adhesive resin cements after artificial aging. Ninety extracted human molars were prepared for ceramic crowns (approximately 20-degree taper, approximately 4-mm axial length) and were divided into 3 groups (n=30). Computer-aided design and computer-aided manufacturing zirconia copings were fabricated. Three surface treatments were applied to the intaglio surface of the copings. The control group received no treatment, the second group was airborne-particle abraded with 50 μm Al2O3, and the third group was treated with 30 μm silica-modified Al2O3, The copings were luted with a self-etch (RelyX Unicem 2), a total-etch (Duo-Link), or a self-etch primer (Panavia F 2.0) adhesive cement. They were stored for 24 hours at 37°C before being artificially aged with 5000 (5°C-55°C) thermal cycles and 100,000 cycles of 70 N dynamic loading. Retention was measured on a universal testing machine under tension, with a crosshead speed of 0.5 mm/min. Statistical analysis was performed with 1-way and 2-way ANOVA. Mean retention values ranged from 0.72 to 3.7 MPa. Surface treatment increased crown retention, but the difference was not statistically significant (P>.05), except for the Duo-Link cement group (P<.05). Analysis of the adhesives revealed that the Duo-Link cement resulted in significantly lower crown retention (P<.05) than the other 2 cements. For zirconia crowns, retention seems to be dependent on cement type rather than surface treatment. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  15. WebAL Comes of Age: A review of the first 21 years of Artificial Life on the Web

    DEFF Research Database (Denmark)

    Taylor, Tim; Auerbach, Joshua E; Bongard, Josh

    2016-01-01

    We present a survey of the first 21 years of web-based artificial life (WebAL) research and applications, broadly construed to include the many different ways in which artificial life and web technologies might intersect. Our survey covers the period from 1994—when the first WebAL work appeared...

  16. A preliminary study of the composition of commercial oil, acrylic and vinyl paints and their behaviour after accelerated ageing conditions

    Directory of Open Access Journals (Sweden)

    Francesca Caterina Izzo

    2014-12-01

    Full Text Available This study is part of a research project dealing with the establishment of monitoring and damage prevention plans for contemporary artworks. For this purpose, some commercial paints, among the most currently used by young artists, were selected: Winton oil paint (Winsor & Newton, UK, Heavy Body acrylic paint (Liquitex, USA and Flashe vinyl paint (Lefranc & Bourgeois, France. The paints were subjected to different treatments of accelerated ageing, the results indicating different behaviour in relation both to the type of binders and pigments present in the different formulations. In particular, it was observed that ageing produced by ozone plays an important role in the stability of the oil paints, above all in those containing organic azo pigments. Thermal ageing, as expected, influences the stability of all the commercial paints examined, with the formation of alteration products and visible changes in the paint films. Ageing produced by moisture clearly affects the synthetic polymer-based paints, particularly evident in the changes in mass. In all cases, the accelerated ageing treatments produced chromatic variations, more evidently for the oil paints containing organic pigment.

  17. Effect of opacifiers and UV absorbers on pigmented maxillofacial silicone elastomer, part 1: color stability after artificial aging.

    Science.gov (United States)

    Han, Ying; Powers, John M; Kiat-Amnuay, Sudarat

    2013-06-01

    Much dissatisfaction with the color instability and reduced lifetime of extraoral maxillofacial prostheses due to degradation has been reported. The purpose of this study was to compare the effect of a UV mineral-based light protecting agent (LP) on the color stability of pigmented maxillofacial silicone elastomer MDX-4210/Type A after artificial aging to 2 widely used opacifiers. Forty-five groups were established (n=225 total). Three different types of opacifiers (LP, titanium white dry pigment [TW], or silicone intrinsic white [SW]) were added to silicone MDX-4210/type A at 3 concentrations (5%, 10%, or 15%) and subsequently combined with each of 5 colors (no pigments [control], red, blue, yellow, or mixed pigments). Artists' oil pigment was used with LP and TW, while intrinsic silicone pigment was used to color SW. Before and after an energy exposure of 450 kJ/m(2), CIE L*a*b* values were measured with a spectrophotometer. The CIELAB 50:50% perceptibility (ΔE*=1.1) and acceptability threshold (ΔE*=3.0) were used to interpret color changes (ΔE*). Color differences after aging were subjected to 3-way ANOVA. Means were compared by the Fisher PLSD intervals at α=.05. The ΔE* values of all groups were below the acceptability threshold of ΔE*=3.0, except for the control group of SW at 10%, which showed the greatest color change (ΔE*=3.1). When mixed pigment groups were considered, at 5% concentration, LP showed the smallest color change, followed by SW and TW (P.05); at 15%, LP showed the smallest color change, followed by TW and SW (P<.05). All 3 opacifiers at all concentrations protected pigmented silicone MDX4-4210/Type A from color degradation. The LP group showed the smallest color changes. Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  18. Deficiency in Poly(ADP-ribose Polymerase-1 (PARP-1 Accelerates Aging and Spontaneous Carcinogenesis in Mice

    Directory of Open Access Journals (Sweden)

    Tatiana S. Piskunova

    2008-01-01

    Full Text Available Genetic and biochemical studies have shown that PARP-1 and poly(ADP-ribosylation play an important role in DNA repair, genomic stability, cell death, inflammation, telomere maintenance, and suppressing tumorigenesis, suggesting that the homeostasis of poly(ADP-ribosylation and PARP-1 may also play an important role in aging. Here we show that PARP-1−/− mice exhibit a reduction of life span and a significant increase of population aging rate. Analysis of noninvasive parameters, including body weight gain, body temperature, estrous function, behavior, and a number of biochemical indices suggests the acceleration of biological aging in PARP-1−/− mice. The incidence of spontaneous tumors in both PARP-1−/− and PARP-1+/+ groups is similar; however, malignant tumors including uterine tumors, lung adenocarcinomas and hepatocellular carcinomas, develop at a significantly higher frequency in PARP-1−/− mice than PARP-1+/+ mice (72% and 49%, resp.; < .05. In addition, spontaneous tumors appear earlier in PARP-1−/− mice compared to the wild type group. Histopathological studies revealed a wide spectrum of tumors in uterus, ovaries, liver, lungs, mammary gland, soft tissues, and lymphoid organs in both groups of the mice. These results demonstrate that inactivation of DNA repair gene PARP-1 in mice leads to acceleration of aging, shortened life span, and increased spontaneous carcinogenesis.

  19. Allowance for insulation aging in the new concept of accelerated life tests of high-voltage power transformers

    International Nuclear Information System (INIS)

    Levit, A.G.; Grechko, O.N.; Shchipunova, N.P.

    1992-01-01

    This paper reports that the existing system of type and acceptance tests of high-voltage transformer insulation does not take into account insulation ageing, which is particularly objectionable with respect to equip-met with reduced insulation levels. Suggested in the paper is a new concept of accelerated life tests based on integrated simulation of basic operating loads, both periodic (surge) and long-term ones; by making a long-term accelerated test simulating the working conditions, with exposure of test object and/or its insulation to periodic operating surges (overvoltages and overcurrents). This test replaces a group of conventional individual acceptance tests and provides more ample and more precise information on performance and dependability of the equipment. The test procedure was checked in test of a small lot of 1600 kVA 35 kV power transformers

  20. Priming of microglia in a DNA-repair deficient model of accelerated aging

    NARCIS (Netherlands)

    Raj, Divya D. A.; Jaarsma, Dick; Holtman, Inge R.; Olah, Marta; Ferreira, Filipa M.; Schaafsma, Wandert; Brouwer, Nieske; Meijer, Michel M.; de Waard, Monique C.; van der Pluijm, Ingrid; Brandt, Renata; Kreft, Karim L.; Laman, Jon D.; de Haan, Gerald; Biber, Knut P. H.; Hoeijmakers, Jan H. J.; Eggen, Bart J. L.; Boddeke, Hendrikus W. G. M.

    Aging is associated with reduced function, degenerative changes, and increased neuroinflammation of the central nervous system (CNS). Increasing evidence suggests that changes in microglia cells contribute to the age-related deterioration of the CNS. The most prominent age-related change of

  1. Immune priming of microglia in a DNA repair deficient model of accelerated aging

    NARCIS (Netherlands)

    Raj, D. A.; Jaarsma, D.; Brouwer, N.; Hoeijmakers, J. H. J.; Eggen, B. J. L.; Biber, K. P. H.; Boddeke, H. W. G. M.

    2012-01-01

    Ageing of brain tissue has been associated with enhanced activity and immune priming of microglia in mice, rats and primates. It is, however, not clear yet whether this age-related microglia activation is due to the intrinsic process of microglia aging or is an adapted response of microglia to the

  2. Aging is associated with decreased maximal life span and accelerated senescence of bone marrow stromal cells

    DEFF Research Database (Denmark)

    Dokkedahl, Karin Stenderup; Justesen, Jeannette; Clausen, Christian

    2003-01-01

    Age-related decrease in bone formation is well described. However, the cellular causes are not known. Thus, we have established cultures of bone marrow stromal cells (MSC) from young (aged 18-29 years, n = 6) and old (aged 68-81 years, n = 5) donors. MSC were serially passaged until reaching maxi...

  3. Effects of endodontic post surface treatment, dentin conditioning, and artificial aging on the retention of glass fiber-reinforced composite resin posts.

    Science.gov (United States)

    Albashaireh, Zakereyya S; Ghazal, Muhamad; Kern, Matthias

    2010-01-01

    Several post surface treatments with or without the application of a bonding agent have been recommended to improve the bond strength of resin cements to posts. A regimen that produces the maximum bond strength of glass fiber-reinforced composite resin posts has not been verified. The purpose of this study was to evaluate the influence of post surface conditioning methods and artificial aging on the retention and microleakage of adhesively luted glass fiber-reinforced composite resin posts. Seventy-two endodontically treated single-rooted teeth were prepared for glass fiber-reinforced composite resin posts. The posts were submitted to 3 different surface treatments (n=24), including no treatment, etching with phosphoric acid, and airborne-particle abrasion. Subgroups of the posts (n=8) were then allocated for 3 different experimental conditions: no artificial aging, no bonding agent; no artificial aging, bonding agent; or artificial aging, bonding agent. The posts were luted with resin cement (Calibra). Post retention was measured in tension at a crosshead speed of 2 mm/min. The posts assigned for microleakage investigation were placed in fuchsin dye for 72 hours. The dislodged posts and the post spaces were examined microscopically to evaluate the mode of failure and explore the microleakage. Data were analyzed by 2-way ANOVA followed by Tukey HSD test (alpha=.05). The mean (SD) retention values for test groups ranged from 269 (63.8) to 349 (52.2) N. The retention values of the airborne-particle-abrasion group were significantly higher than those of the acidic-treatment and no-treatment groups. The application of bonding agent on the post surface produced no significant influence on retention. The mean retention values after artificial aging were significantly higher than without artificial aging. Microscopic evaluation demonstrated that the failure mode was primarily mixed. Treating the surface of the posts with phosphoric acid for 15 seconds before cementation

  4. Development of a lifetime prediction model for lithium-ion batteries based on extended accelerated aging test data

    Science.gov (United States)

    Ecker, Madeleine; Gerschler, Jochen B.; Vogel, Jan; Käbitz, Stefan; Hust, Friedrich; Dechent, Philipp; Sauer, Dirk Uwe

    2012-10-01

    Battery lifetime prognosis is a key requirement for successful market introduction of electric and hybrid vehicles. This work aims at the development of a lifetime prediction approach based on an aging model for lithium-ion batteries. A multivariable analysis of a detailed series of accelerated lifetime experiments representing typical operating conditions in hybrid electric vehicle is presented. The impact of temperature and state of charge on impedance rise and capacity loss is quantified. The investigations are based on a high-power NMC/graphite lithium-ion battery with good cycle lifetime. The resulting mathematical functions are physically motivated by the occurring aging effects and are used for the parameterization of a semi-empirical aging model. An impedance-based electric-thermal model is coupled to the aging model to simulate the dynamic interaction between aging of the battery and the thermal as well as electric behavior. Based on these models different drive cycles and management strategies can be analyzed with regard to their impact on lifetime. It is an important tool for vehicle designers and for the implementation of business models. A key contribution of the paper is the parameterization of the aging model by experimental data, while aging simulation in the literature usually lacks a robust empirical foundation.

  5. Differences in sorption behavior of the herbicide 4-chloro-2-methylphenoxyacetic acid on artificial soils as a function of soil pre-aging.

    Science.gov (United States)

    Waldner, Georg; Friesl-Hanl, Wolfgang; Haberhauer, Georg; Gerzabek, Martin H

    The sorption behavior of the herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA) to three different artificial soil mixtures was investigated. Artificial soils serve as model systems for improving understanding of sorption phenomena. The soils consisted of quartz, ferrihydrite, illite, montmorillonite, and charcoal. In a previous study, several selected mixtures had been inoculated with organic matter, and microbial aging (incubation) had been performed for different periods of time (3, 12, and 18 months) before conducting the sorption experiments. The effect of this pre-incubation time on the sorption behavior was determined. Interaction of MCPA with soil surfaces was monitored by aqueous phase sorption experiments, using high-performance liquid chromatography/ultraviolet and in selected cases Fourier-transformed infrared spectroscopy. The sorption behavior showed large differences between differently aged soils; Freundlich and linear sorption model fits (with sorption constants K f , 1/ n exponents, and K d values, respectively) were given for pH = 3 and the unbuffered pH of ∼7. The largest extent of sorption from diluted solutions was found on the surfaces with a pre-incubation time of 3 months. Sorption increased at acidic pH values. Regarding the influence of aging of artificial soils, the following conclusions were drawn: young artificial soils exhibit stronger sorption at lower concentrations, with a larger K f value than aged soils. A correlation with organic carbon content was not confirmed. Thus, the sorption characteristics of the soils are more influenced by the aging of the organic carbon than by the organic carbon content itself.

  6. Influence of artificial aging on the shear bond strength of zirconia-composite interfaces after pretreatment with new 10-MDP adhesive systems

    Directory of Open Access Journals (Sweden)

    p.c pott

    2016-03-01

    Full Text Available Introduction: This in-vitro study investigates the bond strength of different zirconia composites  with three different modern adhesive systems after artificial aging using thermocycling and water storage. Methods: A total of 90 specimens of zirconia (InCoris, Sirona, Germany, Bernsheim were ground using a 165 µm grit rotating diamond disc. Thirty specimens were additionally treated with either Futurabond U “FBU” (VOCO GmbH, or Futurabond M+ “FBM” (VOCO GmbH or Futurabond M+ in combination with the DCA activator “FBMD” (VOCO GmbH. One of the three different types of composites – BifixSE “BS”, BifixQM “BQ” or GrandioSO “G” (VOCO GmbH – was bonded to the ten specimens of each group. All of the specimens underwent artificial aging using thermocycling between 5°C and 55°C for 5000 cycles followed by water storage for 100 days. Shear bond strength (SBS was determined in a universal testing machine. The type of failure was evaluated using fluorescence microscopy. The data were compared to existing data without artificial aging. Statistical analysis was performed with ANOVA and the Tukey test. Results: FBM and FBMD had higher SBS than FBU in combination with all tested composites, except BifixSE. In nearly all groups, artificial aging had no effect, with the exception of the combination of FBMD with BifixSE, in which there was a significant decrease in SBS after the aging process (p

  7. Is There a Correlation Between Tensile Strength and Retrievability of Cemented Implant-Retained Crowns Using Artificial Aging?

    Science.gov (United States)

    Mehl, Christian; Ali, Shurouk; El Bahra, Shadi; Harder, Sönke; Vollrath, Oliver; Kern, Matthias

    2016-01-01

    The main goal of this in-vitro study was to evaluate whether tensile strength and retrievability of cemented implant-retained crowns correlate when using artificial aging. A total of 128 crowns were fabricated from a cobalt-chromium alloy for 128 tapered titanium abutments (6 degrees taper, 4.3 mm diameter, 4 mm length, Camlog). The crowns were cemented with glass-ionomer (Ketac Cem, 3M) or resin cements (Multilink Implant, Telio CS Cem [Ivoclar Vivadent], Retrieve [Parkell]). Multilink Implant was used without priming. The experimental groups were subjected to either 37,500 thermal cycles between 5°C and 55°C, 1,200,000 chewing cycles, or a combination of both. Control groups were stored for 10 days in deionized water. The crowns were removed with a universal testing machine or a clinically used removal device (Coronaflex, KaVo). Data were statistically analyzed using nonparametrical tests. Retention values were recorded between 31 N and 362 N. Telio CS Cem showed the lowest retention values, followed by Retrieve, Ketac Cem, and Multilink Implant (P≤.0001). The number of removal attempts with the Coronaflex were not significantly different between the cements (P>.05). Thermal cycling and chewing simulation significantly influenced the retrieval of Retrieve Telio CS Cem, and Ketac Cem specimens (P≤.05). Only for Multilink Implant and Telio CS Cem correlations between removal with the universal testing machine and the Coronaflex could be revealed (P≤.0001). Ketac Cem and Multilink Implant (without silane) can be used for a semipermanent cementation. Retrieve and Telio CS Cem are recommendable for a temporary cementation.

  8. Overexpression of eIF-5A2 in mice causes accelerated organismal aging by increasing chromosome instability

    Directory of Open Access Journals (Sweden)

    Chen Leilei

    2011-05-01

    Full Text Available Abstract Background Amplification of 3q26 is one of the most frequent genetic alterations in many human malignancies. Recently, we isolated a novel oncogene eIF-5A2 within the 3q26 region. Functional study has demonstrated the oncogenic role of eIF-5A2 in the initiation and progression of human cancers. In the present study, we aim to investigate the physiological and pathological effect of eIF-5A2 in an eIF-5A2 transgenic mouse model. Methods An eIF-5A2 transgenic mouse model was generated using human eIF-5A2 cDNA. The eIF-5A2 transgenic mice were characterized by histological and immunohistochemistry analyses. The aging phenotypes were further characterized by wound healing, bone X-ray imaging and calcification analysis. Mouse embryo fibroblasts (MEF were isolated to further investigate molecular mechanism of eIF-5A2 in aging. Results Instead of resulting in spontaneous tumor formation, overexpression of eIF-5A2 accelerated the aging process in adult transgenic mice. This included decreased growth rate and body weight, shortened life span, kyphosis, osteoporosis, delay of wound healing and ossification. Investigation of the correlation between cellular senescence and aging showed that cellular senescence is not required for the aging phenotypes in eIF-5A2 mice. Interestingly, we found that activation of eIF-5A2 repressed p19 level and therefore destabilized p53 in transgenic mouse embryo fibroblast (MEF cells. This subsequently allowed for the accumulation of chromosomal instability, such as errors in cell dividing during metaphase and anaphase. Additionally, a significantly increase in number of aneuploidy cells (p Conclusion These observations suggest that eIF-5A2 mouse models could accelerate organismal aging by increasing chromosome instability.

  9. Chronic vitamin C deficiency does not accelerate oxidative stress in ageing brains of guinea pigs

    DEFF Research Database (Denmark)

    Tveden-Nyborg, Pernille; Andersen, Stine Hasselholt; Miyashita, Namiyo

    2012-01-01

      Increased oxidative stress in the brain has consistently been implied in ageing and in several degenerative brain disorders. Acting as a pivotal antioxidant in the brain, vitamin C is preferentially retained during deficiency and may play an essential role in neuroprotection during ageing. Thus......, a lack of vitamin C could be associated with an increase in redox imbalance in the ageing brain. The present study compared oxidative stress of ageing to that of a long-term non-scorbutic vitamin C deficiency in guinea pigs. Adults (3-9 months old) were compared to old (36-42 months old) animals during...... a six-month dietary intervention by assessing vitamin C transport and redox homeostasis in the brain. In contrast to our hypothesis, chronic vitamin C deficiency did not affect the measured markers of oxidative stress in the brains of adult and aged animals. However, aged animals generally showed...

  10. Effects of Accelerated Aging on Soybean Seed Germination Indexes at Laboratory Conditions

    OpenAIRE

    Zahra RASTEGAR; Mohammad SEDGHI; Saeid KHOMARI

    2011-01-01

    Reduction of seedling growth is a consequence of seed deterioration. An experiment was conducted to evaluate the effects of duration of seed aging on soybean seed germination characteristics. Experiment conducted as completely randomized design with 4 replications. The seeds of �DPX� line of soybean with 15-16% moisture were incubated for 3, 7, 10, 14, 17 day at 40�C in sealed containers for ageing treatment and non aged seeds were considered as control. Results showed that rapid aging treatm...

  11. EPR studies of a red wine bottle deposit, and the precipitates from a 'model' wine , and a white wine, both artificially aged

    International Nuclear Information System (INIS)

    Mitri, M.

    2003-01-01

    Full text: A red wine waxy bottle deposit is known to be an anthocyanin-protein compound. The EPR signal shows the presence of a free radical signal, and a Cu(2+) signal with N superhyperfme structure. Subsequently, EPR study of a model wine, catechin being the only phenol, showed a Cu(2+) signal and a free radical signal. The precipitate thrown by the model wine after artificial aging for 3 months at 45C showed a Cu(2+) signal of different bonding, and a free radical signal. All the previously mentioned Cu(2+) signals showed (differing) hyperfine structures. The precipitate thrown by a similarly artificially aged Chardonnay showed a free radical signal, and a Cu(2+) signal without hyperfine structure: no Cu(2+) signal was detected in the mother liquor. The Cu(2+) bonding in each case will be discussed

  12. Further evidence of accelerated aging in bipolar disorder: Focus on GDF-15

    Directory of Open Access Journals (Sweden)

    Yang Fang

    2018-03-01

    Full Text Available Bipolar disorder (BD is a mood disorder associated with cardiovascular and metabolic diseases and premature aging. Growth differentiation factor 15 (GDF-15 has emerged as a biomarker for cardiovascular risk and aging. Our aim was to compare plasma levels of GDF-15 between BD patients and controls, and to evaluate whether they were associated with clinical parameters.

  13. The Effect of Seed Priming and Accelerated Aging on Germination and Physiochemical Changes in Milk Thistle (Silybum marianum

    Directory of Open Access Journals (Sweden)

    Ghasem PARMOON

    2013-05-01

    Full Text Available Effects of seed priming and aging on some physiological characteristics of Milk thistle was studied in a factoral experiment based on Complete Randomized Design (CRD. Tratments were included hydro priming (using distilled water, halo priming (0, 1.5, 3, 4.5 and 6% KNO3 and accelerated aging (0, 2, 4 and 6 days under 45°C and 95% humidity in three replications. Determined parameters were germination charactristics including germination percentage, daily germination speed, mean time of germination, seed vigor index, hypocutile length and hypocutile dry weight. Activity of catalase, peroxidase and polyphenol oxidase were determined at 12 hours after imbibition and seedling stage. According to results of this experiment, germination percentage, seed vigor and seedling growth of seeds were increased under all priming treatments. Improving the catalase and peroxidase activity led to decrease the aging damages. Germination characteristics were improved under both priming treatments at the beginning of germination as well as seedling growth. Polyphenol oxidase activity was increased in the pre-treated seeds but decreased in seedling growth stage. Aging treatments led to reduce the germination percentage, daily germination speed, seed vigor and seedling growth while the germination time was increased. Accelerated aging caused to reduce the germination rate and seedling growth of milk thistle that is probably due to increasing the lipid peroxidation, free radical increment and decreasing the antioxidants activity. The greatest and lowest antioxidants activity, the germination percentage, germination speed and seed vigor were respectively observed under priming using 3% KNO3 concentration and control seeds.

  14. Ethylene propylene cable degradation during LOCA research tests: tensile properties at the completion of accelerated aging

    International Nuclear Information System (INIS)

    Bustard, L.D.

    1982-05-01

    Six ethylene-propylene rubber (EPR) insulation materials were aged at elevated temperature and radiation stress exposures common in cable LOCA qualification tests. Material samples were subjected to various simultaneous and sequential aging simulations in preparation for accident environmental exposures. Tensile properties subsequent to the aging exposure sequences are reported. The tensile properties of some, but not all, specimens were sensitive to the order of radiation and elevated temperature stress exposure. Other specimens showed more severe degradation when simultaneously exposed to radiation and elevated temperature as opposed to the sequential exposure to the same stresses. Results illustrate the difficulty in defining a single test procedure for nuclear safety-related qualification of EPR elastomers. A common worst-case sequential aging sequence could not be identified

  15. Modelling of degradation processes in creep resistant steels through accelerated creep tests after long-term isothermal ageing

    Energy Technology Data Exchange (ETDEWEB)

    Sklenicka, V.; Kucharova, K.; Svoboda, M.; Kroupa, A.; Kloc, L. [Academy of Sciences of the Czech Republic, Brno (Czech Republic). Inst. of Physics of Materials; Cmakal, J. [UJP PRAHA a.s., Praha-Zbraslav (Czech Republic)

    2010-07-01

    Creep behaviour and degradation of creep properties of creep resistant materials are phenomena of major practical relevance, often limiting the lives of components and structures designed to operate for long periods under stress at elevated and/or high temperatures. Since life expectancy is, in reality, based on the ability of the material to retain its high-temperature creep strength for the projected designed life, methods of creep properties assessment based on microstructural evolution in the material during creep rather than simple parametric extrapolation of short-term creep tests are necessary. In this paper we will try to further clarify the creep-strength degradation of selected advanced creep resistant steels. In order to accelerate some microstructural changes and thus to simulate degradation processes in long-term service, isothermal ageing at 650 C for 10 000 h was applied to P91 and P23 steels in their as-received states. The accelerated tensile creep tests were performed at temperature 600 C in argon atmosphere on all steels both in the as-received state and after long-term isothermal ageing, in an effort to obtain a more complete description of the role of microstructural stability in high temperature creep of these steels. Creep tests were followed by microstructural investigations by means of both transmission and scanning electron microscopy and by the thermodynamic calculations. The applicability of the accelerated creep tests was verified by the theoretical modelling of the phase equilibria at different temperatures. It is suggested that under restructed oxidation due to argon atmosphere microstructural instability is the main detrimental process in the long-term degradation of the creep rupture strength of these steels. (orig.)

  16. Oxidative stress and age-related changes in T cells: is thalassemia a model of accelerated immune system aging?

    Science.gov (United States)

    Ghatreh-Samani, Mahdi; Esmaeili, Nafiseh; Soleimani, Masoud; Asadi-Samani, Majid; Ghatreh-Samani, Keihan; Shirzad, Hedayatolah

    2016-01-01

    Iron overload in β-thalassemia major occurs mainly due to blood transfusion, an essential treatment for β-thalassemia major patients, which results in oxidative stress. It has been thought that oxidative stress causes elevation of immune system senescent cells. Under this condition, cells normally enhance in aging, which is referred to as premature immunosenescence. Because there is no animal model for immunosenescence, most knowledge on the immunosenescence pattern is based on induction of immunosenescence. In this review, we describe iron overload and oxidative stress in β-thalassemia major patients and how they make these patients a suitable human model for immunosenescence. We also consider oxidative stress in some kinds of chronic virus infections, which induce changes in the immune system similar to β-thalassemia major. In conclusion, a therapeutic approach used to improve the immune system in such chronic virus diseases, may change the immunosenescence state and make life conditions better for β-thalassemia major patients.

  17. Reduction in podocyte SIRT1 accelerates kidney injury in aging mice.

    Science.gov (United States)

    Chuang, Peter Y; Cai, Weijing; Li, Xuezhu; Fang, Lu; Xu, Jin; Yacoub, Rabi; He, John Cijiang; Lee, Kyung

    2017-09-01

    Both the incidence and prevalence of chronic kidney disease are increasing in the elderly population. Although aging is known to induce kidney injury, the underlying molecular mechanisms remain unclear. Sirtuin 1 (Sirt1), a longevity gene, is known to protect kidney cell injury from various cellular stresses. In previous studies, we showed that the podocyte-specific loss of Sirt1 aggravates diabetic kidney injury. However, the role of Sirt1 in aging-induced podocyte injury is not known. Therefore, in this study we sought to determine the effects of podocyte-specific reduction of Sirt1 in age-induced kidney injury. We employed the inducible podocyte-specific Sirt1 knockdown mice that express shRNA against Sirt1 (Pod-Sirt1 RNAi ) and control mice that express shRNA for luciferase (Pod-Luci RNAi ). We found that reduction of podocyte Sirt1 led to aggravated aging-induced glomerulosclerosis and albuminuria. In addition, urinary level of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker of oxidative stress, was markedly increased in aged Pod-Sirt1 RNAi mice compared with aged Pod-Luci RNAi mice. Although podocyte-specific markers decreased in aged mice compared with the young controls, the decrease was further exacerbated in aged Pod-Sirt1 RNAi compared with Pod-Luci RNAi mice. Interestingly, expression of cellular senescence markers was significantly higher in the glomeruli of Pod-Sirt1 RNAi mice than Pod-Luci RNAi mice, suggesting that cellular senescence may contribute to podocyte loss in aging kidneys. Finally, we confirmed that Pod-Sirt1 RNAi glomeruli were associated with reduced activation of the transcription factors peroxisome proliferator-activated receptor (PPAR)-α coactivador-1 (PGC1α)/PPARγ, forkhead box O (FOXO)3, FOXO4, and p65 NF-κB, through SIRT1-mediated deacetylation. Together, our data suggest that SIRT1 may be a potential therapeutic target to treat patients with aging-related kidney disease.

  18. The Effect of Accelerated Aging on Germination Characteristics, Seed Reserve Utilization and Malondialdehyde Content of Two Wheat Cultivars

    Directory of Open Access Journals (Sweden)

    Maryam Goodarzian Ghahfarokhi

    2014-05-01

    Full Text Available In this study experiment was conducted to evaluated the effect of accelerated aging on germination characteristics, seed reserve utilization and malondialdehyde of two wheat cultivars. The experiment was conducted in factorial with a randomized complete block design with 3 replications. Results of variance analysis showed that, seed aging had significant effects on germination percentage, germination index, normal seedling percentage, mean time to germination, malondialdehyde content, seedling dry weight, weight of utilized (mobilized seed reserve and electrical conductivity. The highest germination percentage, germination index, normal seedling percentage, seedling dry weight and weight of utilized (mobilized seed reserve and the minimum mean time to germination, electrical conductivity and malondialdehyde content were attained from Verinak cultivar under control conditions (0 day aging. Results indicates that germination percentage, germination index, normal seedling percentage, seedling dry weight, and weight of utilized (mobilized seed reserve decreased significantly as seed aging progressed. But, mean time to germination, electrical conductivity and malondialdehyde content increased significantly as seed aging progressed. Also, the decrease in seed reserve mobilization rate was the cause of decreased other traits.

  19. Accelerated aging versus rejuvenation of the immune system in heterochronic parabiosis.

    Science.gov (United States)

    Pishel, Iryna; Shytikov, Dmytro; Orlova, Tatiana; Peregudov, Alex; Artyuhov, Igor; Butenko, Gennadij

    2012-04-01

    The emergence of immune disorders in aging is explained by many factors, including thymus dysfunction, decrease in the proportion and function of naïve T cells, and so forth. There are several approaches to preventing these changes, such as thymus rejuvenation, stem cells recovery, modulation of hormone production, and others. Our investigations of heterochronic parabiosis have shown that benefits of a young immune system, e.g., actively working thymus and regular migration of young hematopoietic stem cells between parabiotic partners, appeared unable to restore the immune system of the old partner. At the same time, we have established a progressive immune impairment in the young heterochronic partners. The mechanism of age changes in the immune system in this model, which may lead to reduced life expectancy, has not been fully understood. The first age-related manifestation in the young partners observed 3 weeks after the surgery was a dramatic increase of CD8(+)44(+) cells population in the spleen. A detailed analysis of further changes revealed a progressive decline of most immunological functions observable for up to 3 months after the surgery. This article reviews possible mechanisms of induction of age-related changes in the immune system of young heterochronic partners. The data obtained suggest the existence of certain factors in the old organisms that trigger aging, thus preventing the rejuvenation process.

  20. The effect of thermal and radiation accelerated ageing on the A. C. electric motor parameters

    International Nuclear Information System (INIS)

    Pica, I.; Segarceanu, D.

    2000-01-01

    The paper presents the main aspects concerning the electric parameters variation of triphase asynchronous motors operating under specific environmental conditions determined by temperature, humidity, radiation. The testing of electric motor capability to meet and exceed the required performances all along its operating life implies the performing of thermal and radiation ageing while the motor is brought, in a relatively short time, under conditions equivalent to those at the end of its service life. The paper describes ageing and measurement techniques and the analyses of electric parameter behavior in these environmental simulated conditions. (author)

  1. Accelerating regional atrophy rates in the progression from normal aging to Alzheimer's disease

    Energy Technology Data Exchange (ETDEWEB)

    Sluimer, Jasper D. [VU University Medical Centre, Department of Diagnostic Radiology, Amsterdam (Netherlands); VU University Medical Centre, Alzheimer Centre, Amsterdam (Netherlands); VU University Medical Centre, Image Analysis Centre, Amsterdam (Netherlands); VU University Medical Centre, Department of Diagnostic Radiology and Alzheimer Centre, PO Box 7057, Amsterdam (Netherlands); Flier, Wiesje M. van der; Scheltens, Philip [VU University Medical Centre, Alzheimer Centre, Amsterdam (Netherlands); VU University Medical Centre, Department of Neurology, Amsterdam (Netherlands); Karas, Giorgos B.; Barkhof, Frederik [VU University Medical Centre, Department of Diagnostic Radiology, Amsterdam (Netherlands); VU University Medical Centre, Alzheimer Centre, Amsterdam (Netherlands); VU University Medical Centre, Image Analysis Centre, Amsterdam (Netherlands); Schijndel, Ronald van [VU University Medical Centre, Image Analysis Centre, Amsterdam (Netherlands); VU University Medical Centre, Department of Informatics, Amsterdam (Netherlands); Barnes, Josephine; Boyes, Richard G. [UCL, Institute of Neurology, Dementia Research Centre, London (United Kingdom); Cover, Keith S. [VU University Medical Centre, Department of Physics and Medical Technology, Amsterdam (Netherlands); Olabarriaga, Silvia D. [University of Amsterdam, Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Academic Medical Centre, Amsterdam (Netherlands); Fox, Nick C. [VU University Medical Centre, Department of Neurology, Amsterdam (Netherlands); UCL, Institute of Neurology, Dementia Research Centre, London (United Kingdom); Vrenken, Hugo [VU University Medical Centre, Alzheimer Centre, Amsterdam (Netherlands); VU University Medical Centre, Image Analysis Centre, Amsterdam (Netherlands); VU University Medical Centre, Department of Physics and Medical Technology, Amsterdam (Netherlands)

    2009-12-15

    We investigated progression of atrophy in vivo, in Alzheimer's disease (AD), and mild cognitive impairment (MCI). We included 64 patients with AD, 44 with MCI and 34 controls with serial MRI examinations (interval 1.8 {+-} 0.7 years). A nonlinear registration algorithm (fluid) was used to calculate atrophy rates in six regions: frontal, medial temporal, temporal (extramedial), parietal, occipital lobes and insular cortex. In MCI, the highest atrophy rate was observed in the medial temporal lobe, comparable with AD. AD patients showed even higher atrophy rates in the extramedial temporal lobe. Additionally, atrophy rates in frontal, parietal and occipital lobes were increased. Cox proportional hazard models showed that all regional atrophy rates predicted conversion to AD. Hazard ratios varied between 2.6 (95% confidence interval (CI) = 1.1-6.2) for occipital atrophy and 15.8 (95% CI = 3.5-71.8) for medial temporal lobe atrophy. In conclusion, atrophy spreads through the brain with development of AD. MCI is marked by temporal lobe atrophy. In AD, atrophy rate in the extramedial temporal lobe was even higher. Moreover, atrophy rates also accelerated in parietal, frontal, insular and occipital lobes. Finally, in nondemented elderly, medial temporal lobe atrophy was most predictive of progression to AD, demonstrating the involvement of this region in the development of AD. (orig.)

  2. Accelerated ageing of blended cements for use in radioactive waste disposal

    International Nuclear Information System (INIS)

    Quillin, K.; Duerden, S.L.; Majumdar, A.J.

    1993-01-01

    An accelerated experimental technique has been developed to study the long term hydration of blended cements that may be used in radioactive waste disposal. This technique has been used to investigate the hydration reactions of Ordinary Portland Cement (OPC) blended with blast furnace slag (ggbs) or pulverised fuel ash (pfa). The effects of high sulphate-bearing and high carbonate-bearing ground waters on the compounds formed on hydration was also investigated. Solid/solution compositional data has been collected during the course of the hydration process and this can be used in the validation of models for the properties of cements. Thomsonite, afwillite, a tobermorite-like phase and thaumasite have been found in addition to the expected cement hydration products and need to be considered in modelling studies of cement hydration. The pH of ground waters reacted with OPC/pfa blends on hydration at 90 o C fell below 8. This is lower than the value required to inhibit the corrosion of steel canisters in a repository. The pH in ground waters reacted with OPC and OPC/ggbs mixes remained above 11, although if the ground waters reacted with OPC/ggbs blends were periodically replaced the pH eventually fell below 10. The experimental procedure could be adapted to test the specific cement and ground water compositions relevant to the design of an underground repository over a range of experimental conditions. (author)

  3. Accelerating regional atrophy rates in the progression from normal aging to Alzheimer's disease

    International Nuclear Information System (INIS)

    Sluimer, Jasper D.; Flier, Wiesje M. van der; Scheltens, Philip; Karas, Giorgos B.; Barkhof, Frederik; Schijndel, Ronald van; Barnes, Josephine; Boyes, Richard G.; Cover, Keith S.; Olabarriaga, Silvia D.; Fox, Nick C.; Vrenken, Hugo

    2009-01-01

    We investigated progression of atrophy in vivo, in Alzheimer's disease (AD), and mild cognitive impairment (MCI). We included 64 patients with AD, 44 with MCI and 34 controls with serial MRI examinations (interval 1.8 ± 0.7 years). A nonlinear registration algorithm (fluid) was used to calculate atrophy rates in six regions: frontal, medial temporal, temporal (extramedial), parietal, occipital lobes and insular cortex. In MCI, the highest atrophy rate was observed in the medial temporal lobe, comparable with AD. AD patients showed even higher atrophy rates in the extramedial temporal lobe. Additionally, atrophy rates in frontal, parietal and occipital lobes were increased. Cox proportional hazard models showed that all regional atrophy rates predicted conversion to AD. Hazard ratios varied between 2.6 (95% confidence interval (CI) = 1.1-6.2) for occipital atrophy and 15.8 (95% CI = 3.5-71.8) for medial temporal lobe atrophy. In conclusion, atrophy spreads through the brain with development of AD. MCI is marked by temporal lobe atrophy. In AD, atrophy rate in the extramedial temporal lobe was even higher. Moreover, atrophy rates also accelerated in parietal, frontal, insular and occipital lobes. Finally, in nondemented elderly, medial temporal lobe atrophy was most predictive of progression to AD, demonstrating the involvement of this region in the development of AD. (orig.)

  4. X-ray screening of the artificially deformed skulls from the Middle Bronze Age of the Low Volga region (paleopathology aspect

    Directory of Open Access Journals (Sweden)

    Pererva Evgenii Vladimirovich

    2013-11-01

    Full Text Available The impact of the deforming structure on the human skull is one of the most challenging and debated questions in modern archeology and anthropology related to artificial deformation of the skull. This is precisely why the present study attempts to study the pathological artificially deformed skulls of representatives of the Catacomb culture originating from burial mound in the Lower Volga region. The analysis of the bone material was carried out with the use of X-ray method of the frontal and lateral views. Thirteen radiographs of skulls with traces of deliberate artificial deformation were examined. The skull shapes, structure of the skull calvarial bones, state of the cranial sutures, signs of intracranial hypertension, and symptoms of vascular and endocrine pathologies were explored and evaluated. The study discovered that Catacomb culture bearers used a variety of methods of skull deformation. Front occipital, occipital ring strain and conventional acrocephaly deformation modes were revealed. The viability and compatibility with normal human activity of artificial skull deformation was observed. In the childhood and newborn periods, individuals have applied constrictive and restrictive devices, trusses andother appliancesfor a few years, their impact couldresultin the intracranial hypertension syndrome, as well as in problems with cranial sutures obliteration. It is very much likely that the use of strain could stimulate the development of the internal frontal hyperostosis (Morgagni's disease which contributed to the emergence of endocrine abnormities in humans. The increased trauma rate of skeleton bones was observed in population of the Middle Bronze Age, as well as ear diseases which makes us once again address the issue of social and cultural phenomenon of intentional artificial deformation of the head tradition.

  5. Fate and bioavailability of 14C-pyrene and 14C-lindane in sterile natural and artificial soils and the influence of aging

    International Nuclear Information System (INIS)

    Šmídová, Klára; Hofman, Jakub; Ite, Aniefiok E.; Semple, Kirk T.

    2012-01-01

    Soil organic matter is used to extrapolate the toxicity and bioavailability of organic pollutants between different soils. However, it has been shown that other factors such as microbial activity are crucial. The aim of this study was to investigate if sterilization can reduce differences in the fate and bioavailability of organic pollutants between different soils. Three natural soils with increasing total organic carbon (TOC) content were collected and three artificial soils were prepared to obtain similar TOCs. Soils were sterilized and spiked with 14 C-pyrene and 14 C-lindane. Total 14 C radioactivity, HPCD extractability, and bioaccumulation in Eisenia fetida were measured over 56 days. When compared to non-sterile soils, differences between the natural and artificial soils and the influence of soil-contaminant contact time were generally reduced in the sterile soils (especially with middle TOC). The results indicate the possibility of using sterile soils as “the worst case scenario” in soil ecotoxicity studies. - Highlights: ► Sterile artificial and natural soils with the same TOC content were used. ► The fate and behavior of two 14 C-POPs were studied over 56 days after spiking. ► Sterilization reduced differences between artificial and natural soils. ► There was no effect of time (aging) in POPs bioaccumulation. ► Sterile soils may be used as “the worst case scenario” in POPs availability studies. - Sterilization reduced the differences in POPs fate and bioavailability between artificial and natural soils with the same TOC content and eliminated the influence of soil contact time.

  6. Relation between motility, accelerated aging and gene expression in selected Drosophila strains under hypergravity conditions

    NARCIS (Netherlands)

    Serrano, P.; van Loon, J.J.W.A.; Javier Medina, F.; Herranz, R.

    2013-01-01

    Motility and aging in Drosophila have proven to be highly modified under altered gravity conditions (both in space and ground simulation facilities). In order to find out how closely connected they are, five strains with altered geotactic response or survival rates were selected and exposed to an

  7. Influence of artificially aged gas diffusion layers on the water management of polymer electrolyte membrane fuel cells analyzed with in-operando synchrotron imaging

    International Nuclear Information System (INIS)

    Arlt, Tobias; Klages, Merle; Messerschmidt, Matthias; Scholta, Joachim; Manke, Ingo

    2017-01-01

    The influence of artificial ageing of gas diffusion layers (GDLs) on the cell performance was investigated using high resolution synchrotron radiography. State-of-the-art GDLs of the type SIGRACET ® SGL 25BC were aged for 0 h, 16 h and 24 h in a hydrogen peroxide solution before they were assembled in the fuel cells. In-operando radiographic measurements were combined with voltage and contact angle measurements. Correlations between applied ageing conditions, GDL water saturation and cell performance were revealed. Hereby, all cell operating conditions were tested several times to estimate the reproducibility of in-operando radiographic fuel cell measurements. Water films at the GDL-membrane and at the GDL-flow field interfaces were found and attributed to MPL cracks and large pores in the GDL structure. The combination of these cracks and pores are assumed to play a crucial role for blocked gas paths, leading to an undersupply with reactants and an increased humidification of the membrane. It is shown that water agglomerations directly impact the membrane resistance. We assume that the hydrophobicity of the fibers inside the GDL is more important for the cell performance than water agglomerations at the membrane-GDL interface. - Highlights: • Influence of ageing of gas diffusion layers on cell performance was investigated. • Cell performance decreased using artificially aged GDLs. • Performance decrease correlated to altered water distribution. • Reproducibility of water thickness measurements with synchrotron imaging.

  8. Reliability of solid-state lighting electrical drivers subjected to WHTOL accelerated aging

    Energy Technology Data Exchange (ETDEWEB)

    Lall, Pradeep; Sakalauku, Peter; Davis, Lynn

    2014-05-27

    An investigation of a solid-state lighting (SSL) luminaire with the focus on the electronic driver which has been exposed to a standard wet hot temperature operating life (WHTOL) of 85% RH and 85°C in order to assess reliability of prolonged exposer to a harsh environment has been conducted. SSL luminaires are beginning introduced as head lamps in some of today's luxury automobiles and may also be fulfilling a variety of important outdoor applications such as overhead street lamps, traffic signals and landscape lighting. SSL luminaires in these environments are almost certain to encounter excessive moisture from humidity and high temperatures for a persistent period of time. The lack of accelerated test methods for LEDs to assess long-term reliability prior to introduction into the marketplace, a need for SSL physics based PHM modeling indicators for assessment and prediction of LED life, as well as the U.S. Department of Energy's R&D roadmap to replace todays lighting with SSL luminaires makes it important to increase the understanding of the reliability of SSL devices, specifically, in harsh environment applications. In this work, a set of SSL electrical drivers were investigated to determine failure mechanisms that occur during prolonged harsh environment applications. Each driver consists of four aluminum electrolytic capacitors (AECs) of three different types and was considered the weakest component inside the SSL electrical driver. The reliability of the electrical driver was assessed by monitoring the change in capacitance and the change in equivalent series resistance for each AEC, as well as monitoring the luminous flux of the SSL luminaire or the output of the electrical driver. The luminous flux of a pristine SSL electrical driver was also monitored in order to detect minute changes in the electrical drivers output and to aid in the investigation of the SSL luminaires reliability. The failure mechanisms of the electrical drivers have been

  9. Development and evaluation of an emulsion containing lycopene for combating acceleration of skin aging

    Directory of Open Access Journals (Sweden)

    Letícia Caramori Cefali

    2015-09-01

    Full Text Available Lycopene, a carotenoid and potent antioxidant is found in large quantities in tomatoes. Lycopene combats diseases, such as cardiovascular disease and different types of cancer, including prostate cancer. However, its topical use in emulsion form for the combat of skin aging is under-explored. The aim of the present study was to develop an emulsion containing lycopene extracted from salad tomatoes and evaluate its cytotoxicity, stability, rheological behavior, antioxidant activity and phytocosmetic permeation. The developed cosmetic comprised an oil phase made up of shea derivatives and was evaluated in terms of its physiochemical stability, spreadability, thermal analysis, rheological behavior, microbiological quality, cytotoxicity, antioxidant activity, cutaneous permeation and retention. The results demonstrate that this phytocosmetic is stable, exhibits satisfactory rheological behavior for a topical formula and is a promising product for combating skin aging.

  10. Aging

    International Nuclear Information System (INIS)

    Finch, S.C.; Beebe, G.W.

    1975-01-01

    The hypothesis that ionizing radiation accelerates natural aging has been under investigation at the Atomic Bomb Casualty Commission since 1959. Postmortem observations of morphologic and chemical changes, tests of functional capacity, physical tests and measurements, clinical laboratory tests, tissue changes, morbidity, and mortality have all been examined by ABCC investigators interested in this hypothesis. These studies have been beset with conceptual difficulties centered on the definition and measurement of aging. An empirical approach early led to the calculation of an index of physiologic age as a linear combination of age-related tests of various organ systems. Most studies have been negative but have not involved the large numbers that might be required to provide strong evidence for or against the hypothesis. Mortality, however, has been examined on the basis of a large sample and over the period 1950-1972 had provided no support for the hypothesis of radiation-accelerated aging. Ionizing radiation dose, of course shorten human life, but its life-shortening effect appears to be the result of specific radiation-induced disease, especially neoplasms. The hypothesis is now much less attractive than it was 10-20 years ago but still has some value in stimulating research on aging. The experience of the A-bomb survivors provides an unusual opportunity for a definitive test of the hypothesis. (auth.)

  11. Can social instability, food deprivation and food inequality accelerate neuronal aging?

    Directory of Open Access Journals (Sweden)

    Fatemeh Moradi

    2012-07-01

    Full Text Available Based on both animal and human studies, inequality in food intake and social instability has adverse effects on the health of individuals and the community. However, it is not known whether social instability, food deprivation and food inequality affect neuronal death and premature aging in young animals. To address this question, the effects of these adverse situations, histopathological changes in hippocampal pyramidal cells and aging process were investigated. and instability and caused significant changes in lipofuscin accumulation in hippocampal pyramidal cells in comparison to the control group (p<0.005. The results also showed a significant increase in the ratio of apoptotic to normal cells in all of the stressed groups compared to the control group (p<0.05. Moreover, application of the social inequality and stresses alone or together modulated levels of cortisol in the experimental group. These findings suggest that food deprivation, inequality and social instability enhance the susceptibility of hippocampal pyramidal cells to apoptosis and premature aging induced by lipofuscin accumulation. Forty eight New Zeeland white male rabbits were divided into six groups and all of them were housed in similar conditions, with 2 animals per cage in a temperature-controlled colony room under light–dark cycle. All experimental animals were fed on standard rabbit commercial pellets and different social situations such as food deprivation, inequality in food intake, and unstable social status were applied to experimental groups during eight weeks. Afterward, lipofuscin accumulation and apoptosis, as main markers of aging, were compared to the control group by Long Ziehl Nelseen staining and the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL reaction assay to reveal the rate of lipofuscin pigment accumulation and TUNEL-reactive apoptotic bodies in the hippocampal pyramidal cells. Serum cortisol level was also measured. Inequality

  12. Acceleration of ageing on lees in red wines by application of ultrasounds

    OpenAIRE

    Fresno, Juan Manuel del; Morata Barrado, Antonio Dionisio; Loira, Iris; Escott, Carlos; Cuerda, Rafael; Calderon Fernandez, Fernando; Suarez Lepe, Jose Antonio

    2017-01-01

    A transfer of parietal polysaccharides and mannoproteins is produced during aging on lees [1]. This transfer of compounds to wine is carried out after cell death. It comes to breakdown of polysaccharides from cell wall (yeast autolysis). This technique increases the density in wines [2] and gives more body and structure. Interactions between yeast polysaccharides and wine tannins will result in decrease of tannic perception (decrease of astringency). Increase of varietal characteristics is pr...

  13. Color stability and degree of cure of direct composite restoratives after accelerated aging.

    Science.gov (United States)

    Sarafianou, Aspasia; Iosifidou, Soultana; Papadopoulos, Triantafillos; Eliades, George

    2007-01-01

    This study evaluated the color changes and amount of remaining C = C bonds (%RDB) in three dental composites after hydrothermal- and photoaging. The materials tested were Estelite sigma, Filtek Supreme and Tetric Ceram. Specimens were fabricated from each material and subjected to L* a* b* colorimetry and FTIR spectroscopy before and after aging. Statistical evaluation of the deltaL,* deltaa,* deltab,* deltaE and %deltaRDB data was performed by one-way ANOVA and Tukey's test. The %RDB data before and after aging were statistically analyzed using two-way ANOVA and Student-Newman-Keuls test. In all cases an alpha = 0.05 significance level was used. No statistically significant differences were found in deltaL*, deltaa*, deltaE and %deltaRDB among the materials tested. Tetric Ceram demonstrated a significant difference in deltab*. All the materials showed visually perceptible (deltaE >1) but clinically acceptable values (deltaE statistically significant differences in %RDB were noticed before and after aging (p statistically significantly different among all the groups tested. No correlation was found between deltaE and %deltaRDB.

  14. The Effect of Artificial Aging on the Tensile Properties of Alclad 24S-T and 24S-T Aluminum Alloy

    Science.gov (United States)

    Kotanchik, Joseph N.; Woods, Walter; Zender, George W.

    1943-01-01

    An experimental study was made to determine the effect of artificial aging on the tensile properties of alclad 24S-T and 24S-T aluminum-alloy sheet material. The results of the tests show that certain combinations of aging time and temperature cause a marked increase in the yield strength and a small increase in the ultimate strength; these increases are accompanied by a very large decrease in elongation. A curve is presented that shows the maximum yield strengths that can be obtained by aging this material at various combinations of time and temperature. The higher values of yield stress are obtained in material aged at relatively longer times and lower temperatures.

  15. Catalyst Stability Benchmarking for the Oxygen Evolution Reaction: The Importance of Backing Electrode Material and Dissolution in Accelerated Aging Studies.

    Science.gov (United States)

    Geiger, Simon; Kasian, Olga; Mingers, Andrea M; Nicley, Shannon S; Haenen, Ken; Mayrhofer, Karl J J; Cherevko, Serhiy

    2017-09-18

    In searching for alternative oxygen evolution reaction (OER) catalysts for acidic water splitting, fast screening of the material intrinsic activity and stability in half-cell tests is of vital importance. The screening process significantly accelerates the discovery of new promising materials without the need of time-consuming real-cell analysis. In commonly employed tests, a conclusion on the catalyst stability is drawn solely on the basis of electrochemical data, for example, by evaluating potential-versus-time profiles. Herein important limitations of such approaches, which are related to the degradation of the backing electrode material, are demonstrated. State-of-the-art Ir-black powder is investigated for OER activity and for dissolution as a function of the backing electrode material. Even at very short time intervals materials like glassy carbon passivate, increasing the contact resistance and concealing the degradation phenomena of the electrocatalyst itself. Alternative backing electrodes like gold and boron-doped diamond show better stability and are thus recommended for short accelerated aging investigations. Moreover, parallel quantification of dissolution products in the electrolyte is shown to be of great importance for comparing OER catalyst feasibility. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Effect of chlorhexidine pretreatment on bond strength durability of caries-affected dentin over 2-year aging in artificial saliva and under simulated intrapulpal pressure.

    Science.gov (United States)

    Mobarak, E H

    2011-01-01

    To evaluate the influence of 2% and 5% chlorhexidine (CHX) pretreatment on bond durability of a self-etching adhesive to normal (ND) and caries-affected (AD) dentin after 2-years of aging in artificial saliva and under simulated intrapulpal pressure (IPP). One hundred twenty freshly extracted carious teeth were ground to expose ND and AD. Specimens were distributed into three equal groups (n=40) according to whether the dentin substrates were pretreated with 2% or 5% CHX or with water (control). Clearfil SE Bond (Kuraray) was applied to both substrates and composite cylinders (0.9 mm diameter and 0.7 mm height) were formed. Pretreatment and bonding were done while the specimens were subjected to 15 mm Hg IPP. After curing, specimens were aged in artificial saliva at 37°C and under IPP at 20 mm Hg until being tested after 24 hours or 2 years (n=20/group). Microshear bond strength was evaluated. Failure modes were determined using a scanning electron microscope (SEM) at 400× magnification. Data were statistically analyzed using three-way analysis of variance (ANOVA); one-way ANOVA tests, and t-test (paged specimens, the 5% CHX group had the highest value followed by the 2% CHX and control groups, although the difference was statistically insignificant. For AD aged specimens, the 5% CHX group revealed statistically higher bond values compared to the 2% CHX and control groups. Fracture modes were predominately adhesive and mixed. Different interfacial silver depositions were recorded. Two percent or 5% CHX pretreatment has no adverse effect on the 24-hour bonding to ND and AD. Five percent CHX was able to diminish the loss in bonding to AD after 2years of aging in artificial saliva and under simulated IPP.

  17. Acceleration of aging processes of cognac alcohol under the action of gamma radiation

    International Nuclear Information System (INIS)

    Lichev, V.; Goranov, N.; Dimov, S.

    1974-01-01

    The paper reports results of studies aimed at speeding up the aging of brandy alcohol by means of gamma radiation. In the course of the studies, the optimal doses for irradiating brandy alcohols obtained from oak extracts and wood were established, and their effects on the composition and taste of alcohols in different experimental treatments were examined. Also, schemes for separate and combined irradiation of brandy alcohols and other materials were developed, and the effects of irradiated wood and oak extracts on the composition and taste of separately irradiated young brandy alcohols were studied. (E.T.)

  18. WebAL Comes of Age: A Review of the First 21 Years of Artificial Life on the Web.

    Science.gov (United States)

    Taylor, Tim; Auerbach, Joshua E; Bongard, Josh; Clune, Jeff; Hickinbotham, Simon; Ofria, Charles; Oka, Mizuki; Risi, Sebastian; Stanley, Kenneth O; Yosinski, Jason

    2016-01-01

    We present a survey of the first 21 years of web-based artificial life (WebAL) research and applications, broadly construed to include the many different ways in which artificial life and web technologies might intersect. Our survey covers the period from 1994-when the first WebAL work appeared-up to the present day, together with a brief discussion of relevant precursors. We examine recent projects, from 2010-2015, in greater detail in order to highlight the current state of the art. We follow the survey with a discussion of common themes and methodologies that can be observed in recent work and identify a number of likely directions for future work in this exciting area.

  19. Artificial intelligence

    CERN Document Server

    Hunt, Earl B

    1975-01-01

    Artificial Intelligence provides information pertinent to the fundamental aspects of artificial intelligence. This book presents the basic mathematical and computational approaches to problems in the artificial intelligence field.Organized into four parts encompassing 16 chapters, this book begins with an overview of the various fields of artificial intelligence. This text then attempts to connect artificial intelligence problems to some of the notions of computability and abstract computing devices. Other chapters consider the general notion of computability, with focus on the interaction bet

  20. Accelerated age-related olfactory decline among type 1 Usher patients.

    Science.gov (United States)

    Ribeiro, João Carlos; Oliveiros, Bárbara; Pereira, Paulo; António, Natália; Hummel, Thomas; Paiva, António; Silva, Eduardo D

    2016-06-22

    Usher Syndrome (USH) is a rare disease with hearing loss, retinitis pigmentosa and, sometimes, vestibular dysfunction. A phenotype heterogeneity is reported. Recent evidence indicates that USH is likely to belong to an emerging class of sensory ciliopathies. Olfaction has recently been implicated in ciliopathies, but the scarce literature about olfaction in USH show conflicting results. We aim to evaluate olfactory impairment as a possible clinical manifestation of USH. Prospective clinical study that included 65 patients with USH and 65 normal age-gender-smoking-habits pair matched subjects. A cross culturally validated version of the Sniffin' Sticks olfaction test was used. Young patients with USH have significantly better olfactory scores than healthy controls. We observe that USH type 1 have a faster ageing olfactory decrease than what happens in healthy subjects, leading to significantly lower olfactory scores in older USH1 patients. Moreover, USH type 1 patients showed significantly higher olfactory scores than USH type 2, what can help distinguishing them. Olfaction represents an attractive tool for USH type classification and pre diagnostic screening due to the low cost and non-invasive nature of the testing. Olfactory dysfunction should be considered among the spectrum of clinical manifestations of Usher syndrome.

  1. Relation Between Motility, Accelerated Aging and Gene Expression in Selected Drosophila Strains under Hypergravity Conditions

    Science.gov (United States)

    Serrano, Paloma; van Loon, Jack J. W. A.; Medina, F. Javier; Herranz, Raúl

    2013-02-01

    Motility and aging in Drosophila have proven to be highly modified under altered gravity conditions (both in space and ground simulation facilities). In order to find out how closely connected they are, five strains with altered geotactic response or survival rates were selected and exposed to an altered gravity environment of 2 g. By analysing the different motile and behavioural patterns and the median survival rates, we show that altered gravity leads to changes in motility, which will have a negative impact on the flies' survival. Previous results show a differential gene expression between sessile samples and adults and confirm that environmentally-conditioned behavioural patterns constrain flies' gene expression and life span. Therefore, hypergravity is considered an environmental stress factor and strains that do not respond to this new environment experience an increment in motility, which is the major cause for the observed increased mortality also under microgravity conditions. The neutral-geotaxis selected strain (strain M) showed the most severe phenotype, unable to respond to variations in the gravitational field. Alternatively, the opposite phenotype was observed in positive-geotaxis and long-life selected flies (strains B and L, respectively), suggesting that these populations are less sensitive to alterations in the gravitational load. We conclude that the behavioural response has a greater contribution to aging than the modified energy consumption in altered gravity environments.

  2. Accelerated age-related olfactory decline among type 1 Usher patients

    Science.gov (United States)

    Ribeiro, João Carlos; Oliveiros, Bárbara; Pereira, Paulo; António, Natália; Hummel, Thomas; Paiva, António; Silva, Eduardo D.

    2016-01-01

    Usher Syndrome (USH) is a rare disease with hearing loss, retinitis pigmentosa and, sometimes, vestibular dysfunction. A phenotype heterogeneity is reported. Recent evidence indicates that USH is likely to belong to an emerging class of sensory ciliopathies. Olfaction has recently been implicated in ciliopathies, but the scarce literature about olfaction in USH show conflicting results. We aim to evaluate olfactory impairment as a possible clinical manifestation of USH. Prospective clinical study that included 65 patients with USH and 65 normal age-gender-smoking-habits pair matched subjects. A cross culturally validated version of the Sniffin’ Sticks olfaction test was used. Young patients with USH have significantly better olfactory scores than healthy controls. We observe that USH type 1 have a faster ageing olfactory decrease than what happens in healthy subjects, leading to significantly lower olfactory scores in older USH1 patients. Moreover, USH type 1 patients showed significantly higher olfactory scores than USH type 2, what can help distinguishing them. Olfaction represents an attractive tool for USH type classification and pre diagnostic screening due to the low cost and non-invasive nature of the testing. Olfactory dysfunction should be considered among the spectrum of clinical manifestations of Usher syndrome. PMID:27329700

  3. Exploring the link between depression and accelerated cellular aging: telomeres hold the key

    Directory of Open Access Journals (Sweden)

    Yu R

    2015-12-01

    Full Text Available Ruby Yu, Jean Woo Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, SAR, China Abstract: Accumulating evidence suggests that telomeres may be a marker for biological aging and telomere length may be affected by multifactorial influences, including cumulative exposure to depression. Associations with telomere length have been reported for major depressive disorder, lifetime duration of depression, higher depression severity, and history of depression. The exact underling mechanisms for these associations have yet to be fully elucidated; however, oxidative stress, chronic inflammation, dysregulated hypothalamus-pituitary-adrenal axis, and altered cortisol levels may be important biochemical mediators. These mediators could also be influenced by psychological stress, unhealthy lifestyle behaviors, or other potential factors, such as childhood abuse, post-traumatic stress disorder, and anxiety that are commonly associated with depression. As such, stress reduction and lifestyle interventions that may affect the telomere maintenance system should be considered for individuals with depression.Keywords: depression, telomere length, biomarkers, cellular ageing

  4. Cardiac remodelling in a baboon model of intrauterine growth restriction mimics accelerated ageing.

    Science.gov (United States)

    Kuo, Anderson H; Li, Cun; Li, Jinqi; Huber, Hillary F; Nathanielsz, Peter W; Clarke, Geoffrey D

    2017-02-15

    Rodent models of intrauterine growth restriction (IUGR) successfully identify mechanisms that can lead to short-term and long-term detrimental cardiomyopathies but differences between rodent and human cardiac physiology and placental-fetal development indicate a need for models in precocial species for translation to human development. We developed a baboon model for IUGR studies using a moderate 30% global calorie restriction of pregnant mothers and used cardiac magnetic resonance imaging to evaluate offspring heart function in early adulthood. Impaired diastolic and systolic cardiac function was observed in IUGR offspring with differences between male and female subjects, compared to their respective controls. Aspects of cardiac impairment found in the IUGR offspring were similar to those found in normal controls in a geriatric cohort. Understanding early cardiac biomarkers of IUGR using non-invasive imaging in this susceptible population, especially taking into account sexual dimorphisms, will aid recognition of the clinical presentation, development of biomarkers suitable for use in humans and management of treatment strategies. Extensive rodent studies have shown that reduced perinatal nutrition programmes chronic cardiovascular disease. To enable translation to humans, we developed baboon offspring cohorts from mothers fed ad libitum (control) or 70% of the control ad libitum diet in pregnancy and lactation, which were growth restricted at birth. We hypothesized that intrauterine growth restriction (IUGR) offspring hearts would show impaired function and a premature ageing phenotype. We studied IUGR baboons (8 male, 8 female, 5.7 years), control offspring (8 male, 8 female, 5.6 years - human equivalent approximately 25 years), and normal elderly (OLD) baboons (6 male, 6 female, mean 15.9 years). Left ventricular (LV) morphology and systolic and diastolic function were evaluated with cardiac MRI and normalized to body surface area. Two-way ANOVA by group

  5. Aging

    International Nuclear Information System (INIS)

    Sasaki, Hideo; Kodama, Kazunori; Yamada, Michiko

    1991-01-01

    The hypothesis that exposure to ionizing radiation accelerates the aging process has been actively investigated at ABCC-RERF since 1958, when longitudinal cohort studies of the Adult Health Study (AHS) and the Life Span Study (LSS) were initiated. In their 1975 overall review of aging studies related to the atomic bomb (A-bomb) survivors, Finch and Beebe concluded that while most studies had shown no correlation between aging and radiation exposure, they had not involved the large numbers of subjects required to provide strong evidence for or against the hypothesis. Extending LSS mortality data up to 1978 did not alter the earlier conclusion that any observed life-shortening was associated primarily with cancer induction rather than with any nonspecific cause. The results of aging studies conducted during the intervening 15 years using data from the same populations are reviewed in the present paper. Using clinical, epidemiological, and laboratory techniques, a broad spectrum of aging parameters have been studied, such as postmortem morphological changes, tests of functional capacity, physical tests and measurements, laboratory tests, tissue changes, and morbidity. With respect to the aging process, the overall results have not been consistent and are generally thought to show no relation to radiation exposure. Although some preliminary results suggest a possible radiation-induced increase in atherosclerotic diseases and acceleration of aging in the T-cell-related immune system, further study is necessary to confirm these findings. In the future, applying the latest gerontological study techniques to data collected from subjects exposed 45 years ago to A-bomb radiation at relatively young ages will present a new body of data relevant to the study of late radiation effects. (author) 103 refs

  6. Influence of artificial aging on the load-bearing capability of straight or angulated zirconia abutments in implant/tooth-supported fixed partial dentures.

    Science.gov (United States)

    Nothdurft, Frank P; Doppler, Klaus E; Erdelt, Kurt J; Knauber, Andreas W; Pospiech, Peter R

    2010-01-01

    The aim of the study was to evaluate the influence of artificial aging on the fracture behavior of straight and angulated zirconia implant abutments used in ZirDesign (Astra Tech) implant/tooth-supported fixed partial dentures (FPDs) in the maxilla. Four different test groups (n = 8) representing anterior implant/tooth-supported FPDs were prepared. Groups 1 and 2 simulated a clinical situation with an ideal implant position (maxillary left central incisor) from a prosthetic point of view, which allowed for the use of a straight, prefabricated zirconia abutment. Groups 3 and 4 simulated a situation with a compromised implant position that required an angulated (20-degree) abutment. OsseoSpeed implants (4.5 3 13 mm, Astra Tech) as well as metal tooth analogs (maxillary right lateral incisor) with simulated periodontal mobility were mounted in polymethyl methacrylate. The FPDs (chromium-cobalt alloy) were cemented with glass ionomer. Groups 2 and 4 were thermomechanically loaded and subjected to static loading until failure. Statistical analysis of force data at the fracture site was performed using nonparametric tests. All samples survived thermomechanical loading. Artificial aging did not lead to a significant decrease in load-bearing capacity in either the straight abutments or the angulated abutments. The restorations that used angulated abutments exhibited higher fracture loads than the restorations with straight abutments (group 1: 209.13 ± 39.11 N; group 2: 233.63 ± 30.68 N; group 3: 324.62 ± 108.07 N; group 4: 361.75 ± 73.82 N). This difference in load-bearing performance was statistically significant, both with and without artificial aging. All abutment fractures occurred below the implant shoulder. Compensation for angulated implant positions with an angulated zirconia abutment is possible without reducing the load-bearing capacity of implant/tooth-supported anterior FPDs.

  7. Artificial ageing of tri-layer polyethylene film used as greenhouse cover under the effect of the temperature and the UV-A simultaneously

    International Nuclear Information System (INIS)

    Dehbi, Abdelkader; Bouaza, Amar; Hamou, Ahmed; Youssef, Boulos; Saiter, Jean Marc

    2010-01-01

    This study helps to understand the mechanism of artificial ageing of a tri-layer film made of low-density polyethylene (LDPE) 'Agrofilm' with additives (color dye, UV and IR stabilizers) used as greenhouse cover under the variations of the temperature with or without UV-A radiations. Ageing was monitored by observing the change of physical properties (free surface energy, color) mechanical and structural effects (Tensile tests, DSC, FTIR) during 5486 h (almost 8 months). The study shows that increase in the free surface energy is proportional to the temperature and that the increase is more pronounced when the film is subjected to the combined action of the temperature and the UV-A radiations. The mechanical tests reveal that both elongation at break and yield stress decrease with the ageing. The calorific curves exhibit two endothermic peaks of melting close together (100 o C and 110 o C) which means the presence in the film of at least two types of crystalline structures. From free surface energy results, the life time of these films under artificial conditions is estimated to 12 months when exposed to 40 o C but drops to 3 months and 18 days when exposed simultaneously to 50 o C and UV-A.

  8. Cigarette smoking accelerated brain aging and induced pre-Alzheimer-like neuropathology in rats.

    Directory of Open Access Journals (Sweden)

    Yuen-Shan Ho

    Full Text Available Cigarette smoking has been proposed as a major risk factor for aging-related pathological changes and Alzheimer's disease (AD. To date, little is known for how smoking can predispose our brains to dementia or cognitive impairment. This study aimed to investigate the cigarette smoke-induced pathological changes in brains. Male Sprague-Dawley (SD rats were exposed to either sham air or 4% cigarette smoke 1 hour per day for 8 weeks in a ventilated smoking chamber to mimic the situation of chronic passive smoking. We found that the levels of oxidative stress were significantly increased in the hippocampus of the smoking group. Smoking also affected the synapse through reducing the expression of pre-synaptic proteins including synaptophysin and synapsin-1, while there were no changes in the expression of postsynaptic protein PSD95. Decreased levels of acetylated-tubulin and increased levels of phosphorylated-tau at 231, 205 and 404 epitopes were also observed in the hippocampus of the smoking rats. These results suggested that axonal transport machinery might be impaired, and the stability of cytoskeleton might be affected by smoking. Moreover, smoking affected amyloid precursor protein (APP processing by increasing the production of sAPPβ and accumulation of β-amyloid peptide in the CA3 and dentate gyrus region. In summary, our data suggested that chronic cigarette smoking could induce synaptic changes and other neuropathological alterations. These changes might serve as evidence of early phases of neurodegeneration and may explain why smoking can predispose brains to AD and dementia.

  9. Prognostics of damage accural in SSL luminaires and drivers subjected to HTSL accelerated aging

    Energy Technology Data Exchange (ETDEWEB)

    Lall, Pradeep [Auburn Univ., AL (United States); Sakalaukus, Peter [Auburn Univ., AL (United States); Davis, Lynn [RTI International, Research Triangle Park, NC (United States)

    2013-07-16

    This paper will show an investigation of off-the-shelf luminaires with the focus on the LED electronic drivers, specifically the aluminum electrolytic capacitors (AECs), that have been aged using high temperature shelf life (HTSL) testing of 135°C in order to prognosticate the remaining useful life of the luminaires. Luminaires have the potential of seeing excessive temperatures when being transported across country or being stored in non-climate controlled warehouses. They are also being used in outdoor applications in desert environments that see little or no humidity but will experience extremely high temperatures during the day. This makes it important to increase our understanding of what effects being stored at high temperatures for a prolonged period of time will have on the usability and survivability of these devices. The U.S. Department of Energy has made a long term commitment to advance the efficiency, understanding and development of solid-state lighting (SSL) and is making a strong push for the acceptance and use of SSL products. In this work, the four AECs of three different types inside each LED electronic driver were studied. The change in capacitance and the change in equivalent series resistance (ESR) of the AECs were measured and considered to be a leading indication of failure of the LED system. These indicators were used to make remaining useful life predictions to develop an algorithm to predict the end of life of the AECs. The luminous flux of a pristine downlight module was also monitored using each LED electronic driver that was subjected to HTSL through the progression of the testing to determine a correlation between the light output of the lamp and the failing components of the LED electronic driver. Prognostic and Health Management (PHM) is a useful tool for assessment of the remaining life of electrical components and is demonstrated for AECs in this work.

  10. Cigarette Smoking Accelerated Brain Aging and Induced Pre-Alzheimer-Like Neuropathology in Rats

    Science.gov (United States)

    Ho, Yuen-Shan; Yang, Xifei; Yeung, Sze-Chun; Chiu, Kin; Lau, Chi-Fai; Tsang, Andrea Wing-Ting; Mak, Judith Choi-Wo; Chang, Raymond Chuen-Chung

    2012-01-01

    Cigarette smoking has been proposed as a major risk factor for aging-related pathological changes and Alzheimer's disease (AD). To date, little is known for how smoking can predispose our brains to dementia or cognitive impairment. This study aimed to investigate the cigarette smoke-induced pathological changes in brains. Male Sprague-Dawley (SD) rats were exposed to either sham air or 4% cigarette smoke 1 hour per day for 8 weeks in a ventilated smoking chamber to mimic the situation of chronic passive smoking. We found that the levels of oxidative stress were significantly increased in the hippocampus of the smoking group. Smoking also affected the synapse through reducing the expression of pre-synaptic proteins including synaptophysin and synapsin-1, while there were no changes in the expression of postsynaptic protein PSD95. Decreased levels of acetylated-tubulin and increased levels of phosphorylated-tau at 231, 205 and 404 epitopes were also observed in the hippocampus of the smoking rats. These results suggested that axonal transport machinery might be impaired, and the stability of cytoskeleton might be affected by smoking. Moreover, smoking affected amyloid precursor protein (APP) processing by increasing the production of sAPPβ and accumulation of β–amyloid peptide in the CA3 and dentate gyrus region. In summary, our data suggested that chronic cigarette smoking could induce synaptic changes and other neuropathological alterations. These changes might serve as evidence of early phases of neurodegeneration and may explain why smoking can predispose brains to AD and dementia. PMID:22606286

  11. Quick Preparation of Moisture-Saturated Carbon Fiber-Reinforced Plastics and Their Accelerated Ageing Tests Using Heat and Moisture

    Directory of Open Access Journals (Sweden)

    Masao Kunioka

    2016-06-01

    Full Text Available A quick method involving the control of heat and water vapor pressure for preparing moisture-saturated carbon fiber-reinforced plastics (CFRP, 8 unidirectional prepreg layers, 1.5 mm thickness, epoxy resin has been developed. The moisture-saturated CFRP sample was obtained at 120 °C and 0.2 MPa water vapor in 72 h by this method using a sterilizer (autoclave. The bending strength and viscoelastic properties measured by a dynamic mechanical analysis (DMA remained unchanged during repetitive saturation and drying steps. No degradation and molecular structural change occurred. Furthermore an accelerated ageing test with two ageing factors, i.e., heat and moisture was developed and performed at 140–160 °C and 0.36–0.62 MPa water vapor pressure by using a sealed pressure-proof stainless steel vessel (autoclave. The bending strength of the sample decreased from 1107 to 319 MPa at 160 °C and 0.63 MPa water vapor pressure in 9 days. Degraded samples were analyzed by DMA. The degree of degradation for samples was analyzed by DMA. CFRP and degraded CFRP samples were analyzed by using a surface and interfacial cutting analysis system (SAICAS and an electron probe micro-analyzer (EPMA equipped in a scanning electron microscope.

  12. Improving motor reliability in nuclear power plants: Volume 2, Functional indicator tests on a small electric motor subjected to accelerated aging

    International Nuclear Information System (INIS)

    Subudhi, M.; Taylor, J.H.; Lofaro, R.; Sugarman, A.C.; Sheets, M.W.; Skreiner, K.M.

    1987-11-01

    A ten horsepower electric motor was artificially aged by plug reverse cycling for test purposes. The motor was manufactured in 1967 and was in service at a commercial nuclear power plant for twelve years. Various tests were performed on the motor throughout the aging process. The motor failed after 3.79 million reversals (3 seconds per reversal) over seven months of testing. Each test parameter was trended to assess its suitability in monitoring aging and service wear degradation in motors. Results and conclusions are discussed relative to the applicability of the tests performed to nuclear power plant motor maintenance programs. 15 refs., 28 figs., 1 tab

  13. In vitro comparison of fracture load of implant-supported, zirconia-based, porcelain- and composite-layered restorations after artificial aging.

    Science.gov (United States)

    Komine, Futoshi; Taguchi, Kohei; Fushiki, Ryosuke; Kamio, Shingo; Iwasaki, Taro; Matsumura, Hideo

    2014-01-01

    This study evaluated fracture load of single-tooth, implant-supported, zirconia-based, porcelain- and indirect composite-layered restorations after artificial aging. Forty-four zirconia-based molar restorations were fabricated on implant abutments and divided into four groups, namely, zirconia-based all-ceramic restorations (ZAC group) and three types of zirconia-based composite-layered restorations (ZIC-P, ZIC-E, and ZIC groups). Before layering an indirect composite material, the zirconia copings in the ZIC-P and ZIC-E groups were primed with Clearfil Photo Bond and Estenia Opaque Primer, respectively. All restorations were cemented on the abutments with glass-ionomer cement and then subjected to thermal cycling and cyclic loading. All specimens survived thermal cycling and cyclic loading. The fracture load of the ZIC-P group (2.72 kN) was not significantly different from that of the ZAC group (3.05 kN). The fracture load of the zirconia-based composite-layered restoration primed with Clearfil Photo Bond (ZIC-P) was comparable to that of the zirconia-based all-ceramic restoration (ZAC) after artificial aging.

  14. Artificial Intelligence.

    Science.gov (United States)

    Information Technology Quarterly, 1985

    1985-01-01

    This issue of "Information Technology Quarterly" is devoted to the theme of "Artificial Intelligence." It contains two major articles: (1) Artificial Intelligence and Law" (D. Peter O'Neill and George D. Wood); (2) "Artificial Intelligence: A Long and Winding Road" (John J. Simon, Jr.). In addition, it contains two sidebars: (1) "Calculating and…

  15. Effect of acid catalysts and accelerated aging on the reaction of methanol with hydroxy-acetaldehyde in bio-oil

    Directory of Open Access Journals (Sweden)

    Bhattacharya, P.

    2010-05-01

    Full Text Available Bio-oil is a promising alternative source of energy produced from fast pyrolysis of biomass. Increasing the viscosity of bio-oil during storage is a major problem that can be controlled by the addition of methanol or other alcohols. This paper reports the results of our investigation of the reactions of short chain alcohols with aldehydes and acids in bio-oil. The reaction of methanol with hydroxyacetaldehyde (HA to form the acetal was catalyzed by the addition of 7 x 10-4 M strong acids such as sulfuric, hydrochloric, p-toluene sulfonic acid, and methanesulfonic acid. HA formed 2,2-dimethoxyethanol (DME, and at 60 oC the equilibrium was reached in less than one hour. Smaller amounts of DME were formed in the absence of strong acid. HA, acetaldehyde, and propanal formed their corresponding acetals when reacted with methanol, ethanol, 1-propanol or 1-butanol. Esters of acetic acid and hydroxyacetic acid were observed from reactions with these same four alcohols. Other acetals and esters were observed by GC/MS analysis of the reaction products. The results from accelerated aging experiments at 90 oC suggest that the presence of methanol slows polymerization by formation of acetals and esters from low molecular weight aldehydes and organic acids.

  16. Towards A Model-based Prognostics Methodology for Electrolytic Capacitors: A Case Study Based on Electrical Overstress Accelerated Aging

    Directory of Open Access Journals (Sweden)

    Gautam Biswas

    2012-12-01

    Full Text Available This paper presents a model-driven methodology for predict- ing the remaining useful life of electrolytic capacitors. This methodology adopts a Kalman filter approach in conjunction with an empirical state-based degradation model to predict the degradation of capacitor parameters through the life of the capacitor. Electrolytic capacitors are important components of systems that range from power supplies on critical avion- ics equipment to power drivers for electro-mechanical actuators. These devices are known for their comparatively low reliability and given their critical role in the system, they are good candidates for component level prognostics and health management. Prognostics provides a way to assess remain- ing useful life of a capacitor based on its current state of health and its anticipated future usage and operational conditions. This paper proposes and empirical degradation model and discusses experimental results for an accelerated aging test performed on a set of identical capacitors subjected to electrical stress. The data forms the basis for developing the Kalman-filter based remaining life prediction algorithm.

  17. Effect of air-abrasion on the retention of zirconia ceramic crowns luted with different cements before and after artificial aging.

    Science.gov (United States)

    Shahin, Ramez; Kern, Matthias

    2010-09-01

    The purpose of this in vitro study was to evaluate the effect of intaglio surface air-abrasion on the retention of CAD/CAM produced zirconia ceramic crowns cemented with three different types of cement. In addition the influence of artificial aging in masticatory simulator and thermocycling was tested. Extracted human premolars were prepared for all-ceramic crowns (12 degrees taper, 3 mm axial length). CAD/CAM zirconia crowns were manufactured. Half of the crowns were air-abraded with 50 microm alumina particles at 0.25 MPa, the rest was left as machined. The crowns were luted with zinc phosphate cement (Hoffmann), glass ionomer cement (Ketac Cem), or composite resin (Panavia 21), subgroups were either stored for 3 days in 37 degrees water bath or stored for 150 days in 37 degrees water bath, with additional 37,500 thermal cycles (5-55 degrees) and 300,000 cycles dynamic loading with 5 kg in a masticatory simulator. Then crown retention was measured in tension at a crosshead speed of 2 mm/min using a universal testing machine. Statistical analysis was performed with three-way ANOVA. Mean retention values were ranged from 2.8 to 7.1 MPa after 3 days and from 1.6 to 6.1 MPa after artificial aging. Air-abrasion significantly increased crown retention (partificial aging decreased retention (p=0.017). In addition, the luting material had a significant influence on retention (p<0.001) with the adhesive luting resin providing the highest retention. The use of phosphate monomer containing composite resin on air-abraded zirconia ceramic can be recommended as most retentive luting method. Copyright 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  18. Effects of Cement, Abutment Surface Pretreatment, and Artificial Aging on the Force Required to Detach Cantilever Fixed Dental Prostheses from Dental Implants.

    Science.gov (United States)

    Kappel, Stefanie; Chepura, Taras; Schmitter, Marc; Rammelsberg, Peter; Rues, Stefan

    To examine the in vitro effects of different cements, abutment surface preconditioning, and artificial aging on the maximum tensile force needed to detach cantilever fixed dental prostheses (FDPs) from dental implants with titanium abutments. A total of 32 tissue-level implants were combined with standardized titanium abutments. For each test group, eight cantilever FDPs were fabricated using selective laser melting (cobalt-chromium [CoCr] alloy). The inner surfaces of the cantilever FDPs and half of the abutments were sandblasted and then joined by use of four different cements (two permanent and two semi-permanent) in two different amounts per cement. Subgroups were tested after either artificial aging (thermocycling and chewing simulation) or 3 days of water storage. Finally, axial pull off-tests were performed for each abutment separately. Cement type and surface pretreatment significantly affected decementation behavior. The highest retention forces (approximately 1,200 N) were associated with sandblasted abutments and permanent cements. With unconditioned abutments, temporary cements (Fu cement (Fu ≈ 100 N), resulted in rather low retention forces. Zinc phosphate cement guaranteed high retention forces. After aging, retention was sufficient only for cementation with zinc phosphate cement and for the combination of sandblasted abutments and glass-ionomer cement. When glass-ionomer cement is used to fix cantilever FDPs on implants, sandblasting of standard titanium abutments may help prevent loss of retention. Retention forces were still high for FDPs fixed with zinc phosphate cement, even when the abutments were not pretreated. Use of permanent cements only, however, is recommended to prevent unwanted loosening of cantilever FDPs.

  19. ACCELERATED AGING OF OLERACEOUS SPECIES SEEDS ENVELHECIMENTO ACELERADO DE SEMENTES DE ESPÉCIES OLERÁCEAS

    Directory of Open Access Journals (Sweden)

    Denis Santiago da Costa

    2011-07-01

    Full Text Available

    The quality of seeds used in the agricultural production process is one of the main factors considered for the development of a crop. This study investigated the effect of vigor level in the performance of six oleraceous species seeds. Commercial seeds of lettuce, eggplant, broccoli, cauliflower, rocket, and tomato were subjected to accelerated aging, for 48 and 72 hours, to obtain lots with three vigor levels, resulting in one regular lot and two lots aged for different periods. After that, the seeds were submitted to germination tests, electrical conductivity, seedling emergence in trays, seedling length and dry weight. The effect of accelerated aging becomes stronger when the exposure time of seeds to high air relative humidity and temperature increases. This exposure reduces more emphatically the seed quality for some species, such as lettuce, cauliflower, and rocket, than for others, such as broccoli, tomato and eggplant. Less vigorous seeds, in addition to lower germination and emergence, show delays in

  20. WetDATA Hub: Democratizing Access to Water Data to Accelerate Innovation through Data Visualization, Predictive Analytics and Artificial Intelligence Applications

    Science.gov (United States)

    Sarni, W.

    2017-12-01

    Water scarcity and poor quality impacts economic development, business growth, and social well-being. Water has become, in our generation, the foremost critical local, regional, and global issue of our time. Despite these needs, there is no water hub or water technology accelerator solely dedicated to water data and tools. There is a need by the public and private sectors for vastly improved data management and visualization tools. This is the WetDATA opportunity - to develop a water data tech hub dedicated to water data acquisition, analytics, and visualization tools for informed policy and business decisions. WetDATA's tools will help incubate disruptive water data technologies and accelerate adoption of current water data solutions. WetDATA is a Colorado-based (501c3), global hub for water data analytics and technology innovation. WetDATA's vision is to be a global leader in water information, data technology innovation and collaborate with other US and global water technology hubs. ROADMAP * Portal (www.wetdata.org) to provide stakeholders with tools/resources to understand related water risks. * The initial activities will provide education, awareness and tools to stakeholders to support the implementation of the Colorado State Water Plan. * Leverage the Western States Water Council Water Data Exchange database. * Development of visualization, predictive analytics and AI tools to engage with stakeholders and provide actionable data and information. TOOLS Education: Provide information on water issues and risks at the local, state, national and global scale. Visualizations: Development of data analytics and visualization tools based upon the 2030 Water Resources Group methodology to support the implementation of the Colorado State Water Plan. Predictive Analytics: Accessing publically available water databases and using machine learning to develop water availability forecasting tools, and time lapse images to support city / urban planning.

  1. Artificial Aging Effects on Cryogenic Fracture Toughness of the Main Structural Alloy for the Super Lightweight Tank

    Science.gov (United States)

    Chen, P. S.; Stanton, W. P.

    2002-01-01

    In 1996, Marshall Space Flight Center developed a multistep heating rate-controlled (MSRC) aging technique that significantly enhanced cryogenic fracture toughness (CFT) and reduced the statistical spread of fracture toughness values in alloy 2195 by controlling the location and size of strengthening precipitate T1. However, it could not be readily applied to flight-related hardware production, primarily because large-scale production furnaces are unable to maintain a heating rate of 0.6 C (1 F)/hr. In August 1996, a new program was initiated to determine whether the MSRC aging treatment could be further modified to facilitate its implementation to flight hardware production. It was successfully redesigned into a simplified two-step aging treatment consisting of 132 C (270 F)/20 hr + 138 C (280 F)/40 hr. Results indicated that two-step aging can achieve the same yield strength levels as those produced by conventional aging while providing greatly improved ductility. Two-step aging proved to be very effective at enhancing CFT, enabling previously rejected materials to meet simulated service requirements. Cryogenic properties are improved by controlling T1 nucleation and growth so that they are promoted in the matrix and suppressed in the subgrain boundaries.

  2. Tip Deflection Determination of a Barrel for the Effect of an Accelerating Projectile Before Firing Using Finite Element and Artificial Neural Network Combined Algorithm

    Directory of Open Access Journals (Sweden)

    Mehmet Akif Koç

    Full Text Available Abstract For realistic applications, design and control engineers have limited modelling options in dealing with some vibration problems that hold many nonlinearity such as non-uniform geometry, variable velocity loadings, indefinite damping cases, etc. For these reasons numerous time consuming experimental studies at high costs must be done for determining the actual behaviour such nonlinear systems. However, using advantages of multiple computational methods like Finite Element Method (FEM together with an Artificial Intelligence (ANN, many complicated engineering problems can be handled and solved to some extent. This study, proposes a new collective method to deal with the nonlinear vibrations of the barrels in order to fulfil accurate shooting expectancy. Using known analytical methods, in practical, to determine dynamic behaviour of the barrel beam is not possible for all conditions of firing that include numerous varieties of ammunition for different purposes, and each projectile of different ammunition has different mass and exit velocity. In order to cover all cases this study proposes a new method that combines a precise FEM with ANN, and can be used for determining the exact dynamic behaviour of a barrel for some cases and then for precisely predicting the behaviour for all other possible cases of firing. In this study, the whole nonlinear behaviour of an antiaircraft barrel were obtained with 3.5% accuracy errors by ANN trained by FEM using calculated analysis results of ammunitions for a particular range. The proposed FEM-ANN combined method can be very useful for design and control engineers in design and control of barrels in order to compensate the effect of nonlinear vibrations of a barrel for achieving a higher shooting accuracy; and can reduce high-cost experimental works.

  3. Acceleration of aged-landfill stabilization by combining partial nitrification and leachate recirculation: A field-scale study

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Jinwook [R& D Center, Samsung Engineering Co., Ltd., 415-10 Woncheon-dong, Youngtong-gu, Suwon, Gyeonggi-do 443-823 (Korea, Republic of); Kim, Seungjin; Baek, Seungcheon [Department of Civil and Environmental Engineering, Hanyang University, Sa 3-dong, Sangnok-gu, Ansan, Gyeonggi-do 426-791 (Korea, Republic of); Lee, Nam-Hoon [Department of Environmental & Energy Engineering, Anyang University, 22 Samdeok-ro, 37 Beon-gil, Manan-gu, Anyang, Gyeonggi-do 430-714 (Korea, Republic of); Park, Seongjun; Lee, Junghun; Lee, Heechang [Department of Civil and Environmental Engineering, Hanyang University, Sa 3-dong, Sangnok-gu, Ansan, Gyeonggi-do 426-791 (Korea, Republic of); Bae, Wookeun, E-mail: wkbae@hanyang.ac.kr [Department of Civil and Environmental Engineering, Hanyang University, Sa 3-dong, Sangnok-gu, Ansan, Gyeonggi-do 426-791 (Korea, Republic of)

    2015-03-21

    Highlights: • To solve the drawbacks (NH{sub 4}{sup +} accumulation) of leachate recirculation, ex-situ SBR was applied. • Produced NO{sub 2}{sup −} was recirculated and denitrified to N{sub 2} in landfill with insufficient carbon source. • Despite the inhibition of methanogenesis by DO and nitrate, CH{sub 4} fraction eventually increased. - Abstract: Leachate recirculation for rapid landfill stabilization can result in the accumulation of high-strength ammonium. An on-site sequencing batch reactor (SBR) was therefore, applied to oxidize the ammonium to nitrite, which was then recirculated to the landfill for denitrification to nitrogen gas. At relatively higher ammonium levels, nitrite accumulated well in the SBR; the nitrite was denitrified stably in the landfill, despite an insufficient biodegradable carbon source in the leachate. As the leachate was recirculated, the methane and carbon dioxide contents produced from the landfill fluctuated, implying that the organic acids and hydrogen produced in the acid production phase acted as the carbon source for denitrification in the landfill. Leachate recirculation combined with ex-situ partial nitrification of the leachate may enhance the biodegradation process by: (a) removing the nitrogen that is contained with the leachate, and (b) accelerating landfill stabilization, because the biodegradation efficiency of landfill waste is increased by supplying sufficient moisture and its byproducts are used as the carbon source for denitrification. In addition, partial nitrification using an SBR has advantages for complete denitrification in the landfill, since the available carbon source is in short supply in aged landfills.

  4. Metodologia para o teste de envelhecimento acelerado em sementes de ervilha Accelerated aging test on pea seeds

    Directory of Open Access Journals (Sweden)

    Warley Marcos Nascimento

    2007-06-01

    ível identificar os lotes de melhor qualidade.Pea production in Brazil uses seeds produced in the country. The objective of this study was to examine the efficiency of the accelerated aging test for vigor evaluation of pea seeds. Five seed lots of cultivar Axé (wrinkled seeds and five seed lots of cultivar Mikado (smooth seeds were used. The initial quality of each seed lot was evaluated by germination test, first counting, and seedling emergence in the field. Seed moisture content was also assessed. The accelerated aging test was set at 41ºC for periods of 24; 48; and 72 hours, with and without saturated NaCl solution. The experiment was carried out in a completely randomized design. The accelerated aging test was efficient for vigor evaluation of pea seeds, and the period of 48 hours at 41ºC, using saturated NaCl solution was the most adequate procedure to indicate vigor levels of pea seeds. However, the seed germination after this period was very low when compared to 24 hour-period (80% for both cultivars, even in higher vigor seed lots (35% for Axé and 38% for Mikado. In the saturated NaCl solution, the period of 48 hours at 41ºC was the most adequate for separate seeds through vigor levels. In these conditions, seed lots of highest vigor showed germination of 68% and 79% for Axé and Mikado, respectively. Results of the germination test, first counting, and seedling emergence were not effective in discriminating physiological seed quality when used individually. Nevertheless, when results from these tests were used all together, it was possible to identify the best seed lots.

  5. Comparison of conventional and plant-extract disinfectant solutions on the hardness and color stability of a maxillofacial elastomer after artificial aging.

    Science.gov (United States)

    Guiotti, Aimée Maria; Goiato, Marcelo Coelho; Dos Santos, Daniela Micheline; Vechiato-Filho, Aljomar José; Cunha, Bruno Guandalini; Paulini, Marcela Borghi; Moreno, Amália; de Almeida, Margarete Teresa Gottardo

    2016-04-01

    Silicone elastomers undergo physical and chemical degradation with disinfecting solutions. Phytotherapy may be a suitable solution for disinfection. However, its effect on the properties of the silicone material is unknown. The purpose of this in vitro study was to evaluate the effect of disinfection with conventional and plant-extract solutions and of artificial aging on the hardness and color stability of a facial silicone associated with pigments and an opacifier. Four hundred specimens of silicone (MDX4-4210) were fabricated (5×6 mm). Two pigment shades and 1 dry opacifier were combined in the tested material, and 4 groups (n=10) were obtained: colorless (GI), colorless with opacifier (GII), medium pigment with opacifier (GIII), and black pigment with opacifier (GIV). Specimens were subjected to disinfection (30 days) using saline solution, water, and neutral soap (digital friction, 30 seconds), chlorhexidine 4%, Hydrastis canadensis, and Cymbopogon nardus extracts (immersion, 10 minutes). Shore A hardness (ASTM D2240) and color analyses were performed before and after disinfection. Specimens were then exposed to 1008 hours of artificial aging (ASTM 53) and subjected to final hardness and color readings. The results were analyzed with ANOVA and the Tukey significant difference test (α=.05). The opacifier increased the hardness (GII). For GII, the H. canadensis solution and the friction with water and soap promoted significantly reduced hardness; the friction also promoted a reduction in this property for GIV. The GIII was not affected after disinfection. A significant difference was found between the ΔE values of the specimens disinfected with H. canadensis, C. nardus, and chlorhexidine, and specimens subjected to saline solution and neutral soap. The hardness of MDX4-4210 after the experimental procedure was considered clinically acceptable for facial prostheses. All groups showed clinically unacceptable color alterations regardless of the disinfecting

  6. An investigation into UV light exposure as an experimental model for artificial aging on tensile strength and force delivery of elastomeric chain.

    Science.gov (United States)

    Wahab, Siti Waznah; Bister, Dirk; Sherriff, Martyn

    2014-02-01

    This study investigated the effect of ultraviolet type A light (UVA) exposure on the tensile properties of elastomeric chain. UVA light exposure was used as model for artificial aging, simulating prolonged storage of elastomeric chain. Tensile strength (n = 60) was measured after exposing Ormco, Forestadent and 3M chains to UVA light for 0, 2, 3, and 4 weeks. Force decay was measured (n = 60) using chain exposed for 5, 10, and 14 days. The chains were subsequently stretched at a constant distance and the resulting forces measured at 0, 1, 24 hours and 7, 14, 21, and 28 days. This test simulated a clinical scenario of pre-stretching and subsequent shortening of elastomeric chain. Tensile strength had statistically significant difference and was directly related to the duration of ultraviolet (UV) light exposure. Forestadent chain, which had the second highest value for the 'as received' product, showed the most consistent values over time with the lowest degradation. Ormco showed the lowest values for 'as received' as well as after UV exposure; 3M chain had the highest loss of tensile strength. Force decay was also significantly different. UV light exposure of 10 days or more appears to mark a 'watershed' between products: 3M had most survivors, Forestadent chain had some survivors, depending on the time the chain was stretched for. None of the Ormco product survived UV light exposure for more than 5 days. UVA light exposure may be used as a model for artificial aging as it reduces force delivery and tensile strength of exposed chains.

  7. The effects of various surface treatments on the shear bond strengths of stainless steel brackets to artificially-aged composite restorations.

    Science.gov (United States)

    Eslamian, Ladan; Borzabadi-Farahani, Ali; Mousavi, Nasim; Ghasemi, Amir

    2011-05-01

    To compare the shear bond strengths (SBS) of stainless steel brackets bonded to artificially-aged composite restorations after different surface treatments. Forty-five premolar teeth were restored with a nano-hybrid composite (Tetric EvoCeram), stored in deionised water for one week and randomly divided into three equal groups: Group I, he restorations were exposed to 5 per cent hydrofluoric acid for 60 seconds; Group II, the restorations were abraded with a micro-etcher (50 Iim alumina particles); Group III, the restorations were roughened with a coarse diamond bur. Similar premolar brackets were bonded to each restoration using the same resin adhesive and the specimens were then cycled in deionised water between 5 degrees C and 55 degrees C (500 cycles). The shear bond strengths were determined with a universal testing machine at a crosshead speed of 1 mm/min. The teeth and brackets were examined under a stereomicroscope and the adhesive remnants on the teeth scored with the adhesive remnant index (ARI). Specimens treated with the diamond bur had a significantly higher SBS (Mean: 18.45 +/- 3.82 MPa) than the group treated with hydrofluoric acid (Mean: 12.85 +/- 5.20 MPa). The mean SBS difference between the air-abrasion (Mean: 15.36 +/- 4.92 MPa) and hydrofluoric acid groups was not significant. High ARI scores occurred following abrasion with a diamond bur (100 per cent) and micro-etcher (80 per cent). In approximately two thirds of the teeth no adhesive was left on the restoration after surface treatment with hydofluoric acid. Surface treatment with a diamond bur resulted in a high bond strength between stainless steel brackets and artificially-aged composite restorations and was considered to be a safe and effective method of surface treatment. Most of the adhesive remained on the tooth following surface treatment with either the micro-etcher or the diamond bur.

  8. Altered expression of the Cdk5 activator-like protein, Cdk5α, causes neurodegeneration, in part by accelerating the rate of aging

    Directory of Open Access Journals (Sweden)

    Joshua Spurrier

    2018-03-01

    Full Text Available Aging is the greatest risk factor for neurodegeneration, but the connection between the two processes remains opaque. This is in part for want of a rigorous way to define physiological age, as opposed to chronological age. Here, we develop a comprehensive metric for physiological age in Drosophila, based on genome-wide expression profiling. We applied this metric to a model of adult-onset neurodegeneration, increased or decreased expression of the activating subunit of the Cdk5 protein kinase, encoded by the gene Cdk5α, the ortholog of mammalian p35. Cdk5α-mediated degeneration was associated with a 27-150% acceleration of the intrinsic rate of aging, depending on the tissue and genetic manipulation. Gene ontology analysis and direct experimental tests revealed that affected age-associated processes included numerous core phenotypes of neurodegeneration, including enhanced oxidative stress and impaired proteostasis. Taken together, our results suggest that Cdk5α-mediated neurodegeneration results from accelerated aging, in combination with cell-autonomous neuronal insults. These data fundamentally recast our picture of the relationship between neurodegeneration and its most prominent risk factor, natural aging.

  9. Accelerated increase and decrease in subjective age as a function of changes in loneliness and objective social indicators over a four-year period: results from the health and retirement study.

    Science.gov (United States)

    Ayalon, Liat; Palgi, Yuval; Avidor, Sharon; Bodner, Ehud

    2016-07-01

    The study examined the role of changes in loneliness and objective social indicators in the formation of changes in subjective age over a four-year period. The Health and Retirement Study is a US nationally representative study of older adults over 50 and their spouse of any age. We restricted the sample to individuals, 65 years of age and older (n = 2591). An accelerated increase in subjective age was defined as an increase in subjective age over the two waves greater than five years. An accelerated decrease in subjective age was defined as a difference that was lower than three years. These were examined against a change in subjective age in the range of three to five years (i.e., change consistent with the passage of time). For 23.4% of the sample, changes in subjective age were consistent with the passage of time. A total of 38.3% had an accelerated decrease in subjective age, whereas 38.3% had an accelerated increase. A decrease in loneliness over the two waves resulted in an accelerated decrease in subjective age, whereas an increase in depressive symptoms resulted in an accelerated increase in subjective age. Changes in objective social indicators, physical difficulties or medical comorbidity did not predict changes in subjective age. This is one of very few studies that examined changes in subjective age over time. Changes in subjective age represent an important construct that corresponding to other changes in subjective experiences.

  10. Degradation of impact fracture during accelerated aging of weld metal on microalloyed steel; Degradacion de la tenacidad al impacto durante el envejecimiento acelerado de soldadura en acero microaleado

    Energy Technology Data Exchange (ETDEWEB)

    Vargas-Arista, B.; Hallen, J. M.; Albiter, A.; Angeles-Chavez, C.

    2008-07-01

    The effect of accelerated aging on the toughness and fracture of the longitudinal weld metal on an API5L-X52 line pipe steel was evaluated by Charpy V-notch impact test, fracture analysis and transmission electron microscopy. Aging was performed at 250 degree centigrade for 100 to 1000 h. The impact results indicated a significant reduction in the fracture energy and impact toughness as a function of aging time, which were achieved by the scanning electron microscope fractography that showed a decrease in the vol fraction of microvoids by Charpy ductile failure with the aging time, which favored the brittle fracture by transgranular cleavage. The minimum vol fraction of microvoids was reached at 500 h due to the peak aged. The microstructural analysis indicated the precipitation of transgranular iron nano carbides in the aged specimens, which was related to the deterioration of toughness and change in the ductile to brittle behavior. (Author) 15 refs.

  11. The effect of heat treatment on microstructure evolution in artificially aged carbon nanotube/Al2024 composites synthesized by mechanical alloying

    International Nuclear Information System (INIS)

    Pérez-Bustamante, R.; Pérez-Bustamante, F.; Maldonado-Orozco, M.C.; Martínez-Sánchez, R.

    2017-01-01

    Although carbon nanotubes/aluminum (CNT/Al) composites are promising materials in the production of structural components, their mechanical behavior under overaging conditions has not been considered. In this paper the effect of CNTs on the microstructural and mechanical behavior of a 2024 aluminum alloy (Al2024) synthesized by mechanical alloying (MA) and powder metallurgy routes is discussed, as well as the effect of aging heat treatments at different temperatures and aging times. The mechanical behavior of composites was screened by hardness measurements as function of aging time. After 96 h of aging time, composites showed mechanical stability in their hardness performance. Images from transmission electron microscopy showed that the mechanical stability of composites was due to a homogeneous dispersion of CNTs in the aluminum matrix and a subsequent alteration in the kinetics of precipitation is due to their presence in the aluminum matrix. Even though strengthening precipitation took place during aging, this was not the main strengthening mechanism observed in composites. - Highlights: • Dispersion of carbon nanotubes during mechanical alloying • Microstructural evolution observed by HRTEM. • Mechanical performance evaluated through micro-hardness test. • Increased mechanical performance at high working temperatures • Acceleration of kinetics of precipitation due to CNTs, and milling conditions

  12. The effect of heat treatment on microstructure evolution in artificially aged carbon nanotube/Al2024 composites synthesized by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Pérez-Bustamante, R. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes No.120, C.P. 31109 Chihuahua, Chih. (Mexico); Pérez-Bustamante, F. [Universidad Autónoma de Chihuahua (UACH), Facultad de Ciencias Químicas, Circuito No. 1 Nuevo Campus Universitario, C.P. 31125 Chihuahua, Chih. (Mexico); Maldonado-Orozco, M.C. [Universidad Autónoma de Chihuahua (UACH), Facultad de Ingeniería, Circuito No. 1 Nuevo Campus Universitario, C.P. 31125 Chihuahua, Chih. (Mexico); Martínez-Sánchez, R., E-mail: roberto.martinez@cimav.edu.mx [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes No.120, C.P. 31109 Chihuahua, Chih. (Mexico)

    2017-04-15

    Although carbon nanotubes/aluminum (CNT/Al) composites are promising materials in the production of structural components, their mechanical behavior under overaging conditions has not been considered. In this paper the effect of CNTs on the microstructural and mechanical behavior of a 2024 aluminum alloy (Al2024) synthesized by mechanical alloying (MA) and powder metallurgy routes is discussed, as well as the effect of aging heat treatments at different temperatures and aging times. The mechanical behavior of composites was screened by hardness measurements as function of aging time. After 96 h of aging time, composites showed mechanical stability in their hardness performance. Images from transmission electron microscopy showed that the mechanical stability of composites was due to a homogeneous dispersion of CNTs in the aluminum matrix and a subsequent alteration in the kinetics of precipitation is due to their presence in the aluminum matrix. Even though strengthening precipitation took place during aging, this was not the main strengthening mechanism observed in composites. - Highlights: • Dispersion of carbon nanotubes during mechanical alloying • Microstructural evolution observed by HRTEM. • Mechanical performance evaluated through micro-hardness test. • Increased mechanical performance at high working temperatures • Acceleration of kinetics of precipitation due to CNTs, and milling conditions.

  13. Artificial Consciousness or Artificial Intelligence

    OpenAIRE

    Spanache Florin

    2017-01-01

    Artificial intelligence is a tool designed by people for the gratification of their own creative ego, so we can not confuse conscience with intelligence and not even intelligence in its human representation with conscience. They are all different concepts and they have different uses. Philosophically, there are differences between autonomous people and automatic artificial intelligence. This is the difference between intelligence and artificial intelligence, autonomous versus a...

  14. [Artificial organs].

    Science.gov (United States)

    Raguin, Thibaut; Dupret-Bories, Agnès; Debry, Christian

    2017-01-01

    Research has been fighting against organ failure and shortage of donations by supplying artificial organs for many years. With the raise of new technologies, tissue engineering and regenerative medicine, many organs can benefit of an artificial equivalent: thanks to retinal implants some blind people can visualize stimuli, an artificial heart can be proposed in case of cardiac failure while awaiting for a heart transplant, artificial larynx enables laryngectomy patients to an almost normal life, while the diabetic can get a glycemic self-regulation controlled by smartphones with an artificial device. Dialysis devices become portable, as well as the oxygenation systems for terminal respiratory failure. Bright prospects are being explored or might emerge in a near future. However, the retrospective assessment of putative side effects is not yet sufficient. Finally, the cost of these new devices is significant even if the advent of three dimensional printers may reduce it. © 2017 médecine/sciences – Inserm.

  15. CR TKA UHMWPE Wear Tested after Artificial Aging of the Vitamin E Treated Gliding Component by Simulating Daily Patient Activities

    Directory of Open Access Journals (Sweden)

    Jens Schwiesau

    2014-01-01

    Full Text Available The wear behaviour of total knee arthroplasty (TKA is dominated by two wear mechanisms: the abrasive wear and the delamination of the gliding components, where the second is strongly linked to aging processes and stress concentration in the material. The addition of vitamin E to the bulk material is a potential way to reduce the aging processes. This study evaluates the wear behaviour and delamination susceptibility of the gliding components of a vitamin E blended, ultra-high molecular weight polyethylene (UHMWPE cruciate retaining (CR total knee arthroplasty. Daily activities such as level walking, ascending and descending stairs, bending of the knee, and sitting and rising from a chair were simulated with a data set received from an instrumented knee prosthesis. After 5 million test cycles no structural failure of the gliding components was observed. The wear rate was with 5.62±0.53 mg/million cycles falling within the limit of previous reports for established wear test methods.

  16. CR TKA UHMWPE wear tested after artificial aging of the vitamin E treated gliding component by simulating daily patient activities.

    Science.gov (United States)

    Schwiesau, Jens; Fritz, Bernhard; Kutzner, Ines; Bergmann, Georg; Grupp, Thomas M

    2014-01-01

    The wear behaviour of total knee arthroplasty (TKA) is dominated by two wear mechanisms: the abrasive wear and the delamination of the gliding components, where the second is strongly linked to aging processes and stress concentration in the material. The addition of vitamin E to the bulk material is a potential way to reduce the aging processes. This study evaluates the wear behaviour and delamination susceptibility of the gliding components of a vitamin E blended, ultra-high molecular weight polyethylene (UHMWPE) cruciate retaining (CR) total knee arthroplasty. Daily activities such as level walking, ascending and descending stairs, bending of the knee, and sitting and rising from a chair were simulated with a data set received from an instrumented knee prosthesis. After 5 million test cycles no structural failure of the gliding components was observed. The wear rate was with 5.62 ± 0.53 mg/million cycles falling within the limit of previous reports for established wear test methods.

  17. Evaluation of in vitro push-out bond strengths of different post-luting systems after artificial aging.

    Science.gov (United States)

    Marigo, Luca; D' Arcangelo, Camillo; DE Angelis, Francesco; Cordaro, Massimo; Vadini, Mirco; Lajolo, Carlo

    2017-02-01

    The purpose of this study was to evaluate the push-out bond strengths of four commercially available adhesive luting systems (two self-adhesive and two etch-and-rinse systems) after mechanical aging. Forty single-rooted anterior teeth were divided into four groups according to the luting cement system used: Cement-One (Group 1); One-Q-adhesive Bond + Axia Core Dual (Group 2); SmartCem® 2 (Group 3); and XP Bond® + Core-X™ Flow (Group 4). Anatomical Post was cemented in groups 1 and 2, and D.T. Light-Post Illusion was cemented in groups 3 and 4. All samples were subjected to masticatory stress simulation consisting of 300,000 cycles applied with a computer-controlled chewing simulator. Push-out bond strength values (MPa) were calculated at cervical, middle, and apical each level, and the total bond strengths were calculated as the averages of the three levels. Statistical analysis was performed with data analysis software and significance was set at Partificial aging, etch-and-rinse luting systems exhibited more homogeneous bond strengths; nevertheless, Cement-One exhibited a total bond strength second only to Core-X Flow.

  18. Transmission electron microscopy study of precipitates in an artificially aged Al–12.7Si–0.7Mg alloy

    International Nuclear Information System (INIS)

    Liu, Fang; Yu, Fuxiao; Zhao, Dazhi; Zuo, Liang

    2015-01-01

    An investigation of Al–12.7Si–0.7Mg alloy aged at 160 °C, 180 °C and 200 °C for 3 h was carried out in order to identify the precipitating phases. Regular transmission and high resolution electron microscopy (TEM and HREM) were employed for this purpose. The studies were focused on the dark spots and needle-shaped precipitates lying in (001) Al plane. Based on the HREM observations, dark spots and needle-shaped precipitates have different characteristics. The results revealed that the ellipsoidal and needle-shaped precipitates along <100> direction of the matrix coexist in the alloy by tilting experiments at given aging condition. The ellipsoidal dark spot precipitates viewing along [001] Al is not cross-sectional image of needle-shaped precipitates along <001> Al . Needle-shaped precipitate is coherent with the matrix. The diffraction pattern associated with the ellipsoidal precipitates is consistent with β″ reported in literature. - Highlights: • Wrought Al–Si–Mg alloy has been investigated to identify the precipitating phases. • The ellipsoidal and needle-shaped precipitates coexist in wrought Al–Si–Mg alloy. • The needle-shaped and ellipsoidal precipitates exhibit different characteristics

  19. Accelerated ageing tests on repair coatings for offshore wind power structures: Presentation held at European Coatings Show Conference 2017, Nuremberg, Germany, 04th April 2017

    OpenAIRE

    Buchbach, Sascha; Momber, A.; Plagemann, P.; Winkels, I.; Marquardt, T.; Viertel, J.

    2017-01-01

    The paper reports on a statistical investigation into effects of surface preparation method, coating type and coating thickness on the performance of OWEA repair coatings under accelerated testing conditions. DoE (Design of Experiments) is used in order to design the tests and to evaluate the effects of the influencing parameters statistically. The ISO 20340 offshore testing scenario is utilized for the acceretaed ageing of the repair c oatings. The pre-existing coating on the test panel was ...

  20. Artificial intelligence

    CERN Document Server

    Ennals, J R

    1987-01-01

    Artificial Intelligence: State of the Art Report is a two-part report consisting of the invited papers and the analysis. The editor first gives an introduction to the invited papers before presenting each paper and the analysis, and then concludes with the list of references related to the study. The invited papers explore the various aspects of artificial intelligence. The analysis part assesses the major advances in artificial intelligence and provides a balanced analysis of the state of the art in this field. The Bibliography compiles the most important published material on the subject of

  1. Die degradation effect on aging rate in accelerated cycling tests of SiC power MOSFET modules

    DEFF Research Database (Denmark)

    Luo, Haoze; Baker, Nick; Iannuzzo, Francesco

    2017-01-01

    In order to distinguish the die and bond wire degradations, in this paper both the die and bond wire resistances of SiC MOSFET modules are measured and tested during the accelerated cycling tests. It is proved that, since the die degradation under specific conditions increases the temperature swing...

  2. Artificial Reefs

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — An artificial reef is a human-made underwater structure, typically built to promote marine life in areas with a generally featureless bottom, control erosion, block...

  3. Natural - synthetic - artificial!

    DEFF Research Database (Denmark)

    Nielsen, Peter E

    2010-01-01

    The terms "natural," "synthetic" and "artificial" are discussed in relation to synthetic and artificial chromosomes and genomes, synthetic and artificial cells and artificial life.......The terms "natural," "synthetic" and "artificial" are discussed in relation to synthetic and artificial chromosomes and genomes, synthetic and artificial cells and artificial life....

  4. The Artificial Intelligence Applications to Learning Programme.

    Science.gov (United States)

    Williams, Noel

    1992-01-01

    Explains the Artificial Intelligence Applications to Learning Programme, which was developed in the United Kingdom to explore and accelerate the use of artificial intelligence (AI) technologies in learning in both the educational and industrial sectors. Highlights include program evaluation, marketing, ownership of information, consortia, and cost…

  5. Metabolic syndrome but not obesity measures are risk factors for accelerated age-related glomerular filtration rate decline in the general population.

    Science.gov (United States)

    Stefansson, Vidar T N; Schei, Jørgen; Solbu, Marit D; Jenssen, Trond G; Melsom, Toralf; Eriksen, Bjørn O

    2018-05-01

    Rapid age-related glomerular filtration rate (GFR) decline increases the risk of end-stage renal disease, and a low GFR increases the risk of mortality and cardiovascular disease. High body mass index and the metabolic syndrome are well-known risk factors for patients with advanced chronic kidney disease, but their role in accelerating age-related GFR decline independent of cardiovascular disease, hypertension and diabetes is not adequately understood. We studied body mass index, waist circumference, waist-hip ratio and metabolic syndrome as risk factors for accelerated GFR decline in 1261 middle-aged people representative of the general population without diabetes, cardiovascular disease or kidney disease. GFR was measured as iohexol clearance at baseline and repeated after a median of 5.6 years. Metabolic syndrome was defined as fulfilling three out of five criteria, based on waist circumference, blood pressure, glucose, high-density lipoprotein cholesterol and triglycerides. The mean GFR decline rate was 0.95 ml/min/year. Neither the body mass index, waist circumference nor waist-hip ratio predicted statistically significant changes in age-related GFR decline, but individuals with baseline metabolic syndrome had a significant mean of 0.30 ml/min/year faster decline than individuals without metabolic syndrome in a multivariable adjusted linear regression model. This association was mainly driven by the triglyceride criterion of metabolic syndrome, which was associated with a significant 0.36 ml/min/year faster decline when analyzed separately. Results differed significantly when GFR was estimated using creatinine and/or cystatin C. Thus, metabolic syndrome, but not the body mass index, waist circumference or waist-hip ratio, is an independent risk factor for accelerated age-related GFR decline in the general population. Copyright © 2017 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

  6. In vitro analysis of different properties of acrylic resins for ocular prosthesis submitted to accelerated aging with or without photopolymerized glaze

    International Nuclear Information System (INIS)

    Santos, Daniela Micheline dos; Nagay, Bruna Egumi; Freitas da Silva, Emily Vivianne; Bonatto, Liliane da Rocha; Sonego, Mariana Vilela; Moreno, Amália; Rangel, Elidiane Cipriano; Cruz, Nilson Cristino da; Goiato, Marcelo Coelho

    2016-01-01

    The effect of a photopolymerized glaze on different properties of acrylic resin (AR) for ocular prostheses submitted to accelerated aging was investigated. Forty discs were divided into 4 groups: N1 AR without glaze (G1); colorless AR without glaze (G2); N1 AR with glaze (G3); and colorless AR with glaze (G4). All samples were polished with sandpaper (240, 600 and 800-grit). In G1 and G2, a 1200-grit sandpaper was also used. In G3 and G4, samples were coated with MegaSeal glaze. Property analysis of color stability, microhardness, roughness, and surface energy, and assays of atomic force microscopy, scanning electron microscopy, and energy-dispersive spectroscopy were performed before and after the accelerated aging (1008 h). Data were submitted to the ANOVA and Tukey Test (p < 0.05). Groups with glaze exhibited statistically higher color change and roughness after aging. The surface microhardness significantly decreased in groups with glaze and increased in groups without glaze. The surface energy increased after the aging, independent of the polishing procedure. All groups showed an increase of surface irregularities. Photopolymerized glaze is an inadequate surface treatment for AR for ocular prostheses and it affected the color stability, roughness, and microhardness. The accelerated aging interfered negatively with the properties of resins. - Highlights: • We analyzed the influence of polishing on two acrylic resins for ocular prosthesis. • We performed different analyzes of esthetic, mechanical and physical properties. • The glaze is an inadequate surface treatment to ocular prosthesis acrylic resin.

  7. In vitro analysis of different properties of acrylic resins for ocular prosthesis submitted to accelerated aging with or without photopolymerized glaze

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Daniela Micheline dos, E-mail: danielamicheline@foa.unesp.br [Department of Dental Materials and Prosthodontics, Aracatuba Dental School, Sao Paulo State University (UNESP), Aracatuba, Sao Paulo (Brazil); Nagay, Bruna Egumi; Freitas da Silva, Emily Vivianne; Bonatto, Liliane da Rocha; Sonego, Mariana Vilela [Department of Dental Materials and Prosthodontics, Aracatuba Dental School, Sao Paulo State University (UNESP), Aracatuba, Sao Paulo (Brazil); Moreno, Amália [Department of Oral Surgery and Pathology, School of Dentistry, Federal University of Minas Gerais (UFMG), Belo Horizonte, Minas Gerais (Brazil); Rangel, Elidiane Cipriano; Cruz, Nilson Cristino da [Technological Plasma Laboratory (LaPTec), Experimental Campus of Sorocaba, UNESP, Sorocaba, Sao Paulo (Brazil); Goiato, Marcelo Coelho [Department of Dental Materials and Prosthodontics, Aracatuba Dental School, Sao Paulo State University (UNESP), Aracatuba, Sao Paulo (Brazil)

    2016-12-01

    The effect of a photopolymerized glaze on different properties of acrylic resin (AR) for ocular prostheses submitted to accelerated aging was investigated. Forty discs were divided into 4 groups: N1 AR without glaze (G1); colorless AR without glaze (G2); N1 AR with glaze (G3); and colorless AR with glaze (G4). All samples were polished with sandpaper (240, 600 and 800-grit). In G1 and G2, a 1200-grit sandpaper was also used. In G3 and G4, samples were coated with MegaSeal glaze. Property analysis of color stability, microhardness, roughness, and surface energy, and assays of atomic force microscopy, scanning electron microscopy, and energy-dispersive spectroscopy were performed before and after the accelerated aging (1008 h). Data were submitted to the ANOVA and Tukey Test (p < 0.05). Groups with glaze exhibited statistically higher color change and roughness after aging. The surface microhardness significantly decreased in groups with glaze and increased in groups without glaze. The surface energy increased after the aging, independent of the polishing procedure. All groups showed an increase of surface irregularities. Photopolymerized glaze is an inadequate surface treatment for AR for ocular prostheses and it affected the color stability, roughness, and microhardness. The accelerated aging interfered negatively with the properties of resins. - Highlights: • We analyzed the influence of polishing on two acrylic resins for ocular prosthesis. • We performed different analyzes of esthetic, mechanical and physical properties. • The glaze is an inadequate surface treatment to ocular prosthesis acrylic resin.

  8. Comparative study of ageing, heat treatment and accelerated carbonation for stabilization of municipal solid waste incineration bottom ash in view of reducing regulated heavy metal/metalloid leaching.

    Science.gov (United States)

    Santos, Rafael M; Mertens, Gilles; Salman, Muhammad; Cizer, Özlem; Van Gerven, Tom

    2013-10-15

    This study compared the performance of four different approaches for stabilization of regulated heavy metal and metalloid leaching from municipal solid waste incineration bottom ash (MSWI-BA): (i) short term (three months) heap ageing, (ii) heat treatment, (iii) accelerated moist carbonation, and (iv) accelerated pressurized slurry carbonation. Two distinct types of MSWI-BA were tested in this study: one originating from a moving-grate furnace incineration operation treating exclusively household refuse (sample B), and another originating from a fluid-bed furnace incineration operation that treats a mixture of household and light industrial wastes (sample F). The most abundant elements in the ashes were Si (20-27 wt.%) and Ca (16-19 wt.%), followed by significant quantities of Fe, Al, Na, S, K, Mg, Ti, and Cl. The main crystalline substances present in the fresh ashes were Quartz, Calcite, Apatite, Anhydrite and Gehlenite, while the amorphous fraction ranged from 56 to 73 wt.%. The leaching values of all samples were compared to the Flemish (NEN 7343) and the Walloon (DIN 38414) regulations from Belgium. Batch leaching of the fresh ashes at natural pH showed that seven elements exceeded at least one regulatory limit (Ba, Cr, Cu, Mo, Pb, Se and Zn), and that both ashes had excess basicity (pH > 12). Accelerated carbonation achieved significant reduction in ash basicity (9.3-9.9); lower than ageing (10.5-12.2) and heat treatment (11.1-12.1). For sample B, there was little distinction between the leaching results of ageing and accelerated carbonation with respect to regulatory limits; however carbonation achieved comparatively lower leaching levels. Heat treatment was especially detrimental to the leaching of Cr. For sample F, ageing was ineffective and heat treatment had marginally better results, while accelerated carbonation delivered the most effective performance, with slurry carbonation meeting all DIN limits. Slurry carbonation was deemed the most

  9. Release and transport of artificial radionuclides from nuclear weapons related activities in the Ob River, Siberia over the course of the nuclear age

    International Nuclear Information System (INIS)

    Sayles, F.L.; Kenna, T.C.; Livingston, H.D.

    1999-01-01

    Studies of sediment cores from lakes on the flood plain of the Ob River, Siberia have been used to develop a history of the release, transport, and deposition of artificial radionuclides related to the development and testing of nuclear weapons over the duration of the nuclear age (∼1950 to the present) in this major Arctic river system. The Ob is of particular importance in this regard as two of the former Soviet Union's major weapons production plants, Mayak and Tomsk-7, and the Semipalatinsk test site are located within the Ob drainage basin. Accidents and intentional releases of radionuclides at both plants have been substantial, raising the issue of transport throughout this extensive river system as well as delivery to the Arctic Ocean. Our studies have included determining sediment profiles of 239,240 Pu, 137 Cs, and the natural nuclide 210 Pb and its parent 226 Ra in a number of cores from the Ob delta, as well as analysis of 239 Pu, 240 Pu, and 237 Np. The latter provide sensitive measures of the presence of non-fallout materials derived from weapons production activities

  10. Fanconi Anemia: A DNA repair disorder characterized by accelerated decline of the hematopoietic stem cell compartment and other features of aging.

    Science.gov (United States)

    Brosh, Robert M; Bellani, Marina; Liu, Yie; Seidman, Michael M

    2017-01-01

    Fanconi Anemia (FA) is a rare autosomal genetic disorder characterized by progressive bone marrow failure (BMF), endocrine dysfunction, cancer, and other clinical features commonly associated with normal aging. The anemia stems directly from an accelerated decline of the hematopoietic stem cell compartment. Although FA is a complex heterogeneous disease linked to mutations in 19 currently identified genes, there has been much progress in understanding the molecular pathology involved. FA is broadly considered a DNA repair disorder and the FA gene products, together with other DNA repair factors, have been implicated in interstrand cross-link (ICL) repair. However, in addition to the defective DNA damage response, altered epigenetic regulation, and telomere defects, FA is also marked by elevated levels of inflammatory mediators in circulation, a hallmark of faster decline in not only other hereditary aging disorders but also normal aging. In this review, we offer a perspective of FA as a monogenic accelerated aging disorder, citing the latest evidence for its multi-factorial deficiencies underlying its unique clinical and cellular features. Published by Elsevier B.V.

  11. Soiling of building envelope surfaces and its effect on solar reflectance – Part II: Development of an accelerated aging method for roofing materials

    Energy Technology Data Exchange (ETDEWEB)

    Sleiman, Mohamad [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kirchstetter, Thomas W. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States); Berdahl, Paul [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Gilbert, Haley E. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Quelen, Sarah [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Marlot, Lea [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Preble, Chelsea V. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States); Chen, Sharon [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Montalbano, Amandine [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Rosseler, Olivier [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Akbari, Hashem [Concordia Univ., Montreal (Canada); Levinson, Ronnen [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Destaillats, Hugo [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2014-01-09

    Highly reflective roofs can decrease the energy required for building air conditioning, help mitigate the urban heat island effect, and slow global warming. However, these benefits are diminished by soiling and weathering processes that reduce the solar reflectance of most roofing materials. Soiling results from the deposition of atmospheric particulate matter and the growth of microorganisms, each of which absorb sunlight. Weathering of materials occurs with exposure to water, sunlight, and high temperatures. This study developed an accelerated aging method that incorporates features of soiling and weathering. The method sprays a calibrated aqueous soiling mixture of dust minerals, black carbon, humic acid, and salts onto preconditioned coupons of roofing materials, then subjects the soiled coupons to cycles of ultraviolet radiation, heat and water in a commercial weatherometer. Three soiling mixtures were optimized to reproduce the site-specific solar spectral reflectance features of roofing products exposed for 3 years in a hot and humid climate (Miami, Florida); a hot and dry climate (Phoenix, Arizona); and a polluted atmosphere in a temperate climate (Cleveland, Ohio). A fourth mixture was designed to reproduce the three-site average values of solar reflectance and thermal emittance attained after 3 years of natural exposure, which the Cool Roof Rating Council (CRRC) uses to rate roofing products sold in the US. This accelerated aging method was applied to 25 products₋single ply membranes, factory and field applied coatings, tiles, modified bitumen cap sheets, and asphalt shingles₋and reproduced in 3 days the CRRC's 3-year aged values of solar reflectance. In conclusion, this accelerated aging method can be used to speed the evaluation and rating of new cool roofing materials.

  12. Hip fracture risk assessment: artificial neural network outperforms conditional logistic regression in an age- and sex-matched case control study.

    Science.gov (United States)

    Tseng, Wo-Jan; Hung, Li-Wei; Shieh, Jiann-Shing; Abbod, Maysam F; Lin, Jinn

    2013-07-15

    Osteoporotic hip fractures with a significant morbidity and excess mortality among the elderly have imposed huge health and economic burdens on societies worldwide. In this age- and sex-matched case control study, we examined the risk factors of hip fractures and assessed the fracture risk by conditional logistic regression (CLR) and ensemble artificial neural network (ANN). The performances of these two classifiers were compared. The study population consisted of 217 pairs (149 women and 68 men) of fractures and controls with an age older than 60 years. All the participants were interviewed with the same standardized questionnaire including questions on 66 risk factors in 12 categories. Univariate CLR analysis was initially conducted to examine the unadjusted odds ratio of all potential risk factors. The significant risk factors were then tested by multivariate analyses. For fracture risk assessment, the participants were randomly divided into modeling and testing datasets for 10-fold cross validation analyses. The predicting models built by CLR and ANN in modeling datasets were applied to testing datasets for generalization study. The performances, including discrimination and calibration, were compared with non-parametric Wilcoxon tests. In univariate CLR analyses, 16 variables achieved significant level, and six of them remained significant in multivariate analyses, including low T score, low BMI, low MMSE score, milk intake, walking difficulty, and significant fall at home. For discrimination, ANN outperformed CLR in both 16- and 6-variable analyses in modeling and testing datasets (p?hip fracture are more personal than environmental. With adequate model construction, ANN may outperform CLR in both discrimination and calibration. ANN seems to have not been developed to its full potential and efforts should be made to improve its performance.

  13. Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of synchrotron X-ray spectromicroscopy and related methods. 1. Artificially aged model samples.

    Science.gov (United States)

    Monico, Letizia; Van der Snickt, Geert; Janssens, Koen; De Nolf, Wout; Miliani, Costanza; Verbeeck, Johan; Tian, He; Tan, Haiyan; Dik, Joris; Radepont, Marie; Cotte, Marine

    2011-02-15

    On several paintings by artists of the end of the 19th century and the beginning of the 20th Century a darkening of the original yellow areas, painted with the chrome yellow pigment (PbCrO(4), PbCrO(4)·xPbSO(4), or PbCrO(4)·xPbO) is observed. The most famous of these are the various Sunflowers paintings Vincent van Gogh made during his career. In the first part of this work, we attempt to elucidate the degradation process of chrome yellow by studying artificially aged model samples. In view of the very thin (1-3 μm) alteration layers that are formed, high lateral resolution spectroscopic methods such as microscopic X-ray absorption near edge (μ-XANES), X-ray fluorescence spectrometry (μ-XRF), and electron energy loss spectrometry (EELS) were employed. Some of these use synchrotron radiation (SR). Additionally, microscopic SR X-ray diffraction (SR μ-XRD), μ-Raman, and mid-FTIR spectroscopy were employed to completely characterize the samples. The formation of Cr(III) compounds at the surface of the chrome yellow paint layers is particularly observed in one aged model sample taken from a historic paint tube (ca. 1914). About two-thirds of the chromium that is present at the surface has reduced from the hexavalent to the trivalent state. The EELS and μ-XANES spectra are consistent with the presence of Cr(2)O(3)·2H(2)O (viridian). Moreover, as demonstrated by μ-XANES, the presence of another Cr(III) compound, such as either Cr(2)(SO(4))(3)·H(2)O or (CH(3)CO(2))(7)Cr(3)(OH)(2) [chromium(III) acetate hydroxide], is likely.

  14. Bond durability of adhesives containing modified-monomer with/without-fluoride after aging in artificial saliva and under intrapulpal pressure simulation.

    Science.gov (United States)

    El-Deeb, H A; Al Sherbiney, H H; Mobarak, E H

    2013-01-01

    To evaluate the dentin bond strength durability of adhesives containing modified-monomer with/without-fluoride after storage in artificial saliva and under intrapulpal pressure simulation (IPPS). The occlusal enamel of 48 freshly extracted teeth was trimmed to expose midcoronal dentin. Roots were sectioned to expose the pulp chamber and to connect the specimens to the pulpal-pressure assembly. Specimens were assigned into four groups (n=12) according to adhesive system utilized: a two-step etch-and-rinse adhesive system (SB, Adper Single Bond 2, 3M ESPE), a two-step self-etch adhesive system (CSE, Clearfil SE Bond, Kuraray Medical Inc), and two single-step self-etch adhesives with the same modified monomer (bis-acrylamide)-one with fluoride (AOF, AdheSE One F, Ivoclar-Vivadent) and the other without (AO, AdheSE One, Ivoclar-Vivadent). Bonding was carried out while the specimens were subjected to 15-mm Hg IPPS. Resin composite (Valux Plus, 3M ESPE) buildups were made. After curing, specimens were aged in artificial saliva and under 20-mm Hg IPPS at 37°C in a specially constructed incubator either for 24 hours or six months prior to testing. Bonded specimens (n=6/group) were sectioned into sticks (n=24/group) with a cross section of 0.9 ± 0.01 mm(2) and subjected to microtensile bond strength (μTBS) testing using a universal testing machine. Data were statistically analyzed using two-way analysis of variance (ANOVA) with repeated measures, one-way ANOVA tests, and a t-test (partificial saliva and under IPPS, yet these values remained significantly higher than those for the other two adhesives with modified monomers. There was no significant difference in the bond strength values between fluoride-containing and fluoride-free self-etch adhesive systems (AOF and AO) after 24 hours or six months. Modes of failure were mainly adhesive and mixed. Based on the results of this study, 1) Fluoride addition did not affect dentin bond durability; and 2) despite the fact that

  15. Physiological response of Erythrina velutina Willd. seeds to accelerated aging / Resposta fsiológica de sementes de Erythrina velutina Willd. ao envelhecimento acelerado

    Directory of Open Access Journals (Sweden)

    Pedro Nóbrega Quintas Colares

    2009-07-01

    Full Text Available Seed vigor testing is an important component of quality control programs, and accelerated aging is a possible option in this process. This study was conducted to investigate procedures to assess seed vigor by the accelerated aging test in forest seeds of Erythrina velutina. The experiment was realized at laboratory conditions at Universidade Federal da Paraíba, in Areia – PB, Brazil Northeast. The seeds were stored in plastic bags and kept at 10°C and 50% relative humidity. Accelerated aging was performed at 41°C during 24, 48, 72, and 96 hours; Accelerated aging test identifed differences among seed lots of high and low physiological quality. Seeds were kept in plastic boxes with 40mL of distilled water in a BOD chamber. Seeds were tested for germination and moisture content before and after aging. The results revealed that the combinations 41°C/72 hours and 45°C/24 hours are appropriate for evaluation of the vigor of Erythrina velutina seeds.A avaliação do vigor de sementes tem sido fundamental dentro de programas de controle de qualidade. O teste de envelhecimento acelerado (EA é uma das opções disponíveis, mas não há informações sufcientes sobre sua efciência para sementes forestais, como as de Erythrina velutina. Para tanto, foi conduzido um experimento em laboratório na Universidade Federal da Paraíba, com o objetivo de estudar procedimentos para condução do teste de EA para avaliar o potencial fsiológico das sementes dessa espécie. O envelhecimento acelerado foi conduzido a 41 e 45°C durante 24, 48, 72 e 96 horas, além da testemunha (sementes não envelhecidas. Realizou-se o teste de emergência das plântulas em campo, a fm de averiguar a qualidade fsiológica das sementes. As sementes foram distribuídas em camada única sobre tela, em caixas plásticas com 40mL de água destilada, no interior de câmara BOD. O teor de água e a germinação das sementes foram determinados antes e após o EA. Os resultados

  16. Artificial sweeteners

    DEFF Research Database (Denmark)

    Raben, Anne Birgitte; Richelsen, Bjørn

    2012-01-01

    Artificial sweeteners can be a helpful tool to reduce energy intake and body weight and thereby risk for diabetes and cardiovascular diseases (CVD). Considering the prevailing diabesity (obesity and diabetes) epidemic, this can, therefore, be an important alternative to natural, calorie-containin......Artificial sweeteners can be a helpful tool to reduce energy intake and body weight and thereby risk for diabetes and cardiovascular diseases (CVD). Considering the prevailing diabesity (obesity and diabetes) epidemic, this can, therefore, be an important alternative to natural, calorie......-containing sweeteners. The purpose of this review is to summarize the current evidence on the effect of artificial sweeteners on body weight, appetite, and risk markers for diabetes and CVD in humans....

  17. Aging precursors and degradation effects of SiC-MOSFET modules under highly accelerated power cycling conditions

    DEFF Research Database (Denmark)

    Luo, Haoze; Iannuzzo, Francesco; Blaabjerg, Frede

    2017-01-01

    A highly accelerated power cycling test platform using current source converter for SiC-MOSFET power modules is proposed. The control principles of delta and average junction temperatures are introduced. By using isolated thermal fibers, the junction temperature (Tj) variations can be monitored...... and compared. As a result, the effects of degradation on the static and dynamic characteristics during conventional operation are discussed. Finally, the research results can help examine the failure precursors and then estimate the remaining useful lifetime of SiC MOSFET modules....

  18. Artificial Intelligence

    CERN Document Server

    Warwick, Kevin

    2011-01-01

    if AI is outside your field, or you know something of the subject and would like to know more then Artificial Intelligence: The Basics is a brilliant primer.' - Nick Smith, Engineering and Technology Magazine November 2011 Artificial Intelligence: The Basics is a concise and cutting-edge introduction to the fast moving world of AI. The author Kevin Warwick, a pioneer in the field, examines issues of what it means to be man or machine and looks at advances in robotics which have blurred the boundaries. Topics covered include: how intelligence can be defined whether machines can 'think' sensory

  19. Artificial intelligence

    International Nuclear Information System (INIS)

    Perret-Galix, D.

    1992-01-01

    A vivid example of the growing need for frontier physics experiments to make use of frontier technology is in the field of artificial intelligence and related themes. This was reflected in the second international workshop on 'Software Engineering, Artificial Intelligence and Expert Systems in High Energy and Nuclear Physics' which took place from 13-18 January at France Telecom's Agelonde site at La Londe des Maures, Provence. It was the second in a series, the first having been held at Lyon in 1990

  20. Artificial organs and transplantation.

    Science.gov (United States)

    Splendiani, G; Cipriani, S; Vega, A; Casciani, C U

    2003-05-01

    Nowadays artificial devices are not able to totally and undefinitely replace the loss of function of all vital organs and artificial organs can be used only to bridge the time to transplantation, which must be considered the first choice in the therapeutical approach for many chronic diseases. Since general population aging process is leading to an increase of organ demand, the gap between performed and requested transplantation is hard to fill. Xenotransplantation is nowadays only an experimental alternative solution and we have to do our best using available artificial organs to increase and improve the survival of patients waiting for transplantation. In this meeting we particularly dealt about organ function replacing therapy, especially regarding the kidney, heart, liver, pancreas and ear.

  1. Microwave-assisted synthesis of N-pyrazole ureas and the p38alpha inhibitor BIRB 796 for study into accelerated cell ageing.

    Science.gov (United States)

    Bagley, Mark C; Davis, Terence; Dix, Matthew C; Widdowson, Caroline S; Kipling, David

    2006-11-21

    Microwave irradiation of substituted hydrazines and beta-ketoesters gives 5-aminopyrazoles in excellent yield, which can be transformed to the corresponding N-carbonyl derivatives by treatment with an isocyanate or chloroformate. Derivatization of 4-nitronaphth-1-ol using predominantly microwave heating methods and reaction with an N-pyrazole carbamate provides a rapid route to the N-pyrazole urea BIRB 796 in high purity, as a potent and selective inhibitor of p38alpha mitogen-activated protein kinase for the study of accelerated ageing in Werner syndrome cells.

  2. Study of accelerated aging of polymeric surge arresters and insulators used in high voltage lines; Estudo sobre o envelhecimento acelerado de para-raios e isoladores polimericos usados em linhas de alta tensao

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira Junior, Joao B. de; Castro Junior, Joao B. de; Silva, Maria Elisa S.R. e; Freitas, Roberto F.S.; Sousa, Ricardo G. de [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Engenharia Quimica. Lab. Ciencia e Tecnologia de Polimeros; Souza, Breno P.G. de [CEMIG Distribuicao S.A., Belo Horizonte, MG (Brazil)], e-mail: sousarg@ufmg.br

    2011-07-01

    The use of polymeric materials in the electrical system has dramatically increased in recent years, in quantity as well as in quality. However, the use of these materials has been very empirical, being necessary a more directed and well based study towards their application in energy sector, especially concerning their early deterioration. In this study, the behavior of some surge arresters and insulators, used in power lines, after suffering aging artificial weathering chamber, was investigated. The absorption spectra in the infrared (FTIR) was used as analytical technique for study of aging. Of the five samples tested, only one showed an oxidation process after 1500 hours of artificial weathering. (author)

  3. Artificial Intelligence.

    Science.gov (United States)

    Wash, Darrel Patrick

    1989-01-01

    Making a machine seem intelligent is not easy. As a consequence, demand has been rising for computer professionals skilled in artificial intelligence and is likely to continue to go up. These workers develop expert systems and solve the mysteries of machine vision, natural language processing, and neural networks. (Editor)

  4. Effects of surface treatment and artificial aging on the shear bond strength of orthodontic brackets bonded to four different provisional restorations.

    Science.gov (United States)

    Al Jabbari, Youssef S; Al Taweel, Sara M; Al Rifaiy, Mohammed; Alqahtani, Mohammed Q; Koutsoukis, Theodoros; Zinelis, Spiros

    2014-07-01

    To evaluate the combined effects of material type, surface treatment, and thermocycling on the bond strength of orthodontic brackets to materials used for the fabrication of provisional crowns. Four materials were included in this study (ProTemp, Trim Plus, Trim II, and Superpont C+B). Sixty cylindrical specimens (1 × 3 cm) were prepared from each material and equally divided into three groups. The first group was ground with silica carbide paper, the second was polished with pumice, and the last group was sandblasted with 50-µm aluminum oxide particles. Stainless-steel maxillary central incisor brackets (Victory Series, 3M) were bonded to the provisional material specimens with Transbond XT light-cured composite resin, and half of the specimens from each group were thermocycled 500 times in 5°C and 55°C water baths. Then the brackets were debonded with shear testing, and the results were statistically analyzed by three-way analysis of variance and Tukey's multiple-comparison tests at α  =  0.05. Adhesive Remnant Index (ARI) was also identified. Before and after thermocycling, ProTemp materials showed the highest shear bond strength with orthodontic brackets (10.3 and 13.1 MPa, respectively). The statistical analysis indicated an interaction among the three independent variables (P < .05) and statistically significant differences in bond strength among provisional materials (P < .001), surface treatments (P < .001), and thermocycling (P < .05). According to the ARI, most groups demonstrated adhesive failure. The provisional material type, surface treatment, and artificial aging have a significant effect on bond strength. Sandblasting treatment exerts a beneficial effect on shear bond strength.

  5. Study of a laboratory-scaled new method for the accelerated continuous ageing of wine spirits by applying ultrasound energy.

    Science.gov (United States)

    Delgado-González, M J; Sánchez-Guillén, M M; García-Moreno, M V; Rodríguez-Dodero, M C; García-Barroso, C; Guillén-Sánchez, D A

    2017-05-01

    During the ageing of brandies, many physicochemical processes take place involving the distilled spirit and the wood of the casks. Because of these reactions, the polyphenolic content of brandies and their content of organic acids increase with the ageing. These reactions are slow, and the ageing of high-quality brandies takes several years. In this paper, the development of a system that uses the circulation of the wine distillate through encapsulated American oak chips and the application of ultrasound energy with the aim of producing aged wine spirits has been carried out, and the influences of the operation variables over the characteristics of the produced drink have been measured. With that proposal, the influence of different powers of ultrasound, and also the influence of the movement of the liquor through oak chips, was determined first. This way, the results show that higher powers of ultrasound, of nearly 40W/L, in addition with the movement of the spirit, improve the extraction of phenolic compounds in a 33.94%, after seven days of ageing. Then, applying Youden and Steiner's experimental design, eight experiments of ageing were performed, and the samples obtained by this new method were analysed to obtain information related to their physicochemical and oenological characterisation in order to determine the experimental conditions that produce the best ageing results. This way, the best spirit produced by this new method of ageing is obtained with a high alcoholic strength of the distilled wine and a high quantity of oak chips, and with room temperature and high flow rate. In addition, the presence of oxygen in the sample and the absence of light increase the quality of the produced spirit. Finally, the application of ultrasound energy in large pulses is related with the improvement of two important ageing markers: the intensity of the colour and the TPI. As a last experiment, we applied this ageing method to five varietal spirits. The sensorial

  6. AGE and their receptor RAGE in systemic autoimmune diseases : An inflammation propagating factor contributing to accelerated atherosclerosis

    NARCIS (Netherlands)

    Nienhuis, Hans L. A.; Westra, Johanna; Smit, Andries J.; Limburg, Pieter C.; Kallenberg, Cees G. M.; Bijl, Marc

    2009-01-01

    Systemic autoimmune diseases are associated with inflammation, and oxidative stress favouring the formation of advanced glycation endproducts (AGE), able to modulate cellular functions by activation of receptor for advanced glycation endproducts (RAGE). As RAGE expression is increased in an

  7. A Novel Approach to Detect Accelerated Aged and Surface-Mediated Degradation in Explosives by UPLC-ESI-MS.

    Energy Technology Data Exchange (ETDEWEB)

    Beppler, Christina L [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-12-01

    A new approach was created for studying energetic material degradation. This approach involved detecting and tentatively identifying non-volatile chemical species by liquid chromatography-mass spectrometry (LC-MS) with multivariate statistical data analysis that form as the CL-20 energetic material thermally degraded. Multivariate data analysis showed clear separation and clustering of samples based on sample group: either pristine or aged material. Further analysis showed counter-clockwise trends in the principal components analysis (PCA), a type of multivariate data analysis, Scores plots. These trends may indicate that there was a discrete shift in the chemical markers as the went from pristine to aged material, and then again when the aged CL-20 mixed with a potentially incompatible material was thermally aged for 4, 6, or 9 months. This new approach to studying energetic material degradation should provide greater knowledge of potential degradation markers in these materials.

  8. Accelerated aging tests on ENEA-ASE solar coating for receiver tube suitable to operate up to 550 °C

    Science.gov (United States)

    Antonaia, A.; D'Angelo, A.; Esposito, S.; Addonizio, M. L.; Castaldo, A.; Ferrara, M.; Guglielmo, A.; Maccari, A.

    2016-05-01

    A patented solar coating for evacuated receiver, based on innovative graded WN-AlN cermet layer, has been optically designed and optimized to operate at high temperature with high performance and high thermal stability. This solar coating, being designed to operate in solar field with molten salt as heat transfer fluid, has to be thermally stable up to the maximum temperature of 550 °C. With the aim of determining degradation behaviour and lifetime prediction of the solar coating, we chose to monitor the variation of the solar absorptance αs after each thermal annealing cycle carried out at accelerated temperatures under vacuum. This prediction method was coupled with a preliminary Differential Thermal Analysis (DTA) in order to give evidence for any chemical-physical coating modification in the temperature range of interest before performing accelerated aging tests. In the accelerated aging tests we assumed that the temperature dependence of the degradation processes could be described by Arrhenius behaviour and we hypothesized that a linear correlation occurs between optical parameter variation rate (specifically, Δαs/Δt) and degradation process rate. Starting from Δαs/Δt values evaluated at 650 and 690 °C, Arrhenius plot gave an activation energy of 325 kJ mol-1 for the degradation phenomenon, where the prediction on the coating degradation gave a solar absorptance decrease of only 1.65 % after 25 years at 550 °C. This very low αs decrease gave evidence for an excellent stability of our solar coating, also when employed at the maximum temperature (550 °C) of a solar field operating with molten salt as heat transfer fluid.

  9. Accelerated Aging of the Traditional Greek Distillate Tsipouro Using Wooden Chips. Part I: Effect of Static Maceration vs. Ultrasonication on the Polyphenol Extraction and Antioxidant Activity

    Directory of Open Access Journals (Sweden)

    Theodora Taloumi

    2017-01-01

    Full Text Available The Greek traditional grape marc distillate Tsipouro was subjected to accelerated aging, using wooden chips from acacia, cherry, chestnut and oak wood. The processes included treatments under static maceration and ultrasonication and the evolution of the total polyphenol concentration was monitored over a period of 30 days. During this period, leaching of polyphenols from the chips into the distillate was found to obey first-order kinetics, but no statistical differences were shown between the two treatments regarding the enrichment of the liquid in polyphenolic substances. The determination of the antioxidant activity demonstrated that aging with chestnut chips may provide Tsipouro with particularly strong radical scavenging and reducing effects, highlighting its importance as a material that could be used to turn distillates into foods with functional properties.

  10. The effect of elevated temperature on the accelerated aging of LiCoO2/mesocarbon microbeads batteries

    International Nuclear Information System (INIS)

    Guan, Ting; Sun, Shun; Gao, Yunzhi; Du, Chunyu; Zuo, Pengjian; Cui, Yingzhi; Zhang, Lingling; Yin, Geping

    2016-01-01

    Highlights: • The effect of elevated temperature on aging of lithium-ion battery is investigated. • The active lithium loss, polarization and cathode decay lead to a capacity fade. • The decay rate of the cathode is faster at elevated temperature. • The performance of the cathode is mainly affected by SEI film. • The proper temperature range ensuring no changes in aging mechanism is proposed. - Abstract: This work studies the aging processes of commercial LiCoO 2 /mesocarbon microbeads (MCMB) cells which are cycled at 25 °C, 35 °C, 45 °C respectively at the 0.6 C charge/discharge rate and 30% depth of discharge. The capacity degradation of the cells is fast at elevated temperature, and the cycle life tested at 45 °C is about a quarter of the cycling time at 25 °C. The fresh and the aged cells are disassembled to characterize the morphology and the composition of electrode surface, as well as the bulk structure and the electrochemical performance of single electrode. It is found that the formation of SEI film and the polarization of the full cell lead to state of charge (SOC) shift in the cathode. The cathode SOC shift and the decay in the reversible capacity of LiCoO 2 cathode dominate the aging of the full cell. The former is the prevailing aging factor at 25 °C, while the latter factor becomes the leading cause of cell aging at 45 °C. The unstable and thick SEI film on the cathode under elevated temperature influences the lithium ion diffusion, resulting in the increased polarization and the decreased intrinsic performance of LiCoO 2 cathode. The proper range of test temperature ensuring no changes in aging mechanism and the decay rate of capacity caused by each aging factor are proposed by analyzing the performance of the full cells and the electrodes. After comparing the test results, it is concluded that the aging process at 45 °C is not the same as that at room temperature.

  11. Can Accelerators Accelerate Learning?

    International Nuclear Information System (INIS)

    Santos, A. C. F.; Fonseca, P.; Coelho, L. F. S.

    2009-01-01

    The 'Young Talented' education program developed by the Brazilian State Funding Agency (FAPERJ)[1] makes it possible for high-schools students from public high schools to perform activities in scientific laboratories. In the Atomic and Molecular Physics Laboratory at Federal University of Rio de Janeiro (UFRJ), the students are confronted with modern research tools like the 1.7 MV ion accelerator. Being a user-friendly machine, the accelerator is easily manageable by the students, who can perform simple hands-on activities, stimulating interest in physics, and getting the students close to modern laboratory techniques.

  12. Can Accelerators Accelerate Learning?

    Science.gov (United States)

    Santos, A. C. F.; Fonseca, P.; Coelho, L. F. S.

    2009-03-01

    The 'Young Talented' education program developed by the Brazilian State Funding Agency (FAPERJ) [1] makes it possible for high-schools students from public high schools to perform activities in scientific laboratories. In the Atomic and Molecular Physics Laboratory at Federal University of Rio de Janeiro (UFRJ), the students are confronted with modern research tools like the 1.7 MV ion accelerator. Being a user-friendly machine, the accelerator is easily manageable by the students, who can perform simple hands-on activities, stimulating interest in physics, and getting the students close to modern laboratory techniques.

  13. Artificial Consciousness or Artificial Intelligence

    Directory of Open Access Journals (Sweden)

    Spanache Florin

    2017-05-01

    Full Text Available Artificial intelligence is a tool designed by people for the gratification of their own creative ego, so we can not confuse conscience with intelligence and not even intelligence in its human representation with conscience. They are all different concepts and they have different uses. Philosophically, there are differences between autonomous people and automatic artificial intelligence. This is the difference between intelligence and artificial intelligence, autonomous versus automatic. But conscience is above these differences because it is neither conditioned by the self-preservation of autonomy, because a conscience is something that you use to help your neighbor, nor automatic, because one’s conscience is tested by situations which are not similar or subject to routine. So, artificial intelligence is only in science-fiction literature similar to an autonomous conscience-endowed being. In real life, religion with its notions of redemption, sin, expiation, confession and communion will not have any meaning for a machine which cannot make a mistake on its own.

  14. USE OF ARTIFICIAL INTELLIGENCE TECHNIQUES IN QUALITY IMPROVING PROCESS

    OpenAIRE

    KALİTE İYİLEŞTİRME SÜRECİNDE YAPAY ZEKÃ KAYA; Orhan ENGİN

    2005-01-01

    Today, changing of competition conditions and customer preferences caused to happen many differences in the viewpoint of firms' quality studies. At the same time, improvements in computer technologies accelerated use of artificial intelligence. Artificial intelligence technologies are being used to solve many industry problems. In this paper, we investigated the use of artificial intelligence techniques to solve quality problems. The artificial intelligence techniques, which are used in quali...

  15. Action of exogenous ascorbic acid on physiological quality of cowpea seeds artificially agedAção do ácido ascórbico exógeno na qualidade fisiológica de sementes de feijão de corda envelhecidas artificialmente

    Directory of Open Access Journals (Sweden)

    Jean Carlos de Araújo Brilhante

    2013-06-01

    Full Text Available The aim of this study was to evaluate the effects of pre-treatment and post-treatment with ascorbic acid in reducing the damage caused by aging in cowpea seeds, which were aged in artificial accelerated aging chamber (45°C, 99% relative humidity in the dark for 72 h and it were subjected to four treatments: T1 – non-aged seeds were not treated with ascorbic acid (AsA; T2 – non-aged seeds treated with AsA; T3 – seeds before aging were subjected to a treatment with AsA to 0.85 mM; T4 – seeds after aging were subjected to a treatment with a 0.85 mM AsA. The aging of seeds for 72 h (T2 caused significant damage in the cell membranes of cowpea seeds, as evidenced by a increase in electrolyte leakage, higher level of lipid peroxidation and a lower germination percentage, when compared with the control (T1. T4 results were like the control treatment, with a lower electrolyte leakage and lipid peroxidation, well as a higher germination percentage, when compared with T2. The exogenous application of 0.85 mM ascorbic acid in cowpea seeds after artificial aging can mitigate its detrimental effects on the membranes integrity and seed physiological quality.O objetivo desse estudo foi avaliar os efeitos do pré e pós-tratamento com ácido ascórbico na redução dos danos ocasionados pelo envelhecimento em sementes de feijão de corda, as quais foram envelhecidas em câmara de envelhecimento artificial (45 ºC, 99% U.R., no escuro por 72 h, sendo submetidas a quatro tratamentos: T1 – sementes não envelhecidas e não tratadas com ácido ascórbico (AsA; T2 – sementes envelhecidas e não tratadas com AsA; T3 – sementes que antes do envelhecimento foram submetidas a um tratamento com AsA a 0,85 mM; T4 – sementes que após o envelhecimento foram submetidas a um tratamento com AsA a 0,85 mM. O envelhecimento das sementes por 72 h (T2 provocou danos significativos nas membranas celulares das sementes de feijão de corda, como foi evidenciado pelo

  16. Calculation of apparent age by linear combination of facial skin parameters: a predictive tool to evaluate the efficacy of cosmetic treatments and to assess the predisposition to accelerated aging.

    Science.gov (United States)

    Dicanio, Denise; Sparacio, Rose; Declercq, Lieve; Corstjens, Hugo; Muizzuddin, Neelam; Hidalgo, Julie; Giacomoni, Paolo U; Jorgensen, Lise; Maes, Daniel

    2009-12-01

    The estimated apparent age (EAA) was estimated by a panel of trained experts, for the individuals in a cohort. Twelve independent clinical, biophysical and biochemical parameters measured on facial skin, have been identified by multiple regression analysis, which influence the EAA of a person of chronological age (CA) (under eye lines, clinically assessed crow's feet, age spots, clinically evaluated firmness, forehead lines, pores, lip lines, instrumentally evaluated firmness, instrumentally evaluated crow feet, skin texture, in vivo fluorescence related to proliferation and glycation). An algorithm has been devised to obtain the calculated age score (CAS) in a cohort of 452 female volunteers, as CAS(n) = ∑RCiPi(n) (i = 1-13, n = 1-452 and P13 = 1) where the coefficients Ci are obtained by minimizing the difference EAA - CAS, and Pi(n) are the experimental values of the i-th parameter for the n-th volunteer. The determination of CAS before and after a specific cosmetic or pharmacological anti-aging treatment can be used to objectively assess the efficacy of the treatment. The comparison of EAA(n) and of CAS(n) with CA(n) allows one to predict the susceptibility of an individual's face to undergo aging. It has been observed that the biophysical and biochemical parameters play a relevant role in the assessment of the predisposition of skin to undergo accelerated aging.

  17. Senescence-accelerated mouse prone 8 (SAMP8) as a model of age-related hearing loss.

    Science.gov (United States)

    Marie, Aurore; Larroze-Chicot, Philippe; Cosnier-Pucheu, Sylvie; Gonzalez-Gonzalez, Sergio

    2017-08-24

    Hearing loss is the most common form of sensory impairment in humans, affecting 5.3% worldwide population. In industrial countries, age-related hearing loss is a major health problem affecting one-third of individuals over 65years old. However, the physiological and molecular changes involved in this senescence process remain unclear. In this study, we determined the influence of age on auditory brainstem response (ABR) and the distortion product otoacoustic emissions (DPOAE) in the premature senescence mouse model SAMP8 for five months. We showed a progressive increase of ABR thresholds and a decrease of distortion product amplitude from 37days old in SAMP8 compared to CBA mice. The data we show here provide new knowledge in functional auditory changes during the senescence process and open up new opportunities for the development of new drugs involved in age-related hearing loss treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Artificial Intelligence.

    Science.gov (United States)

    Lawrence, David R; Palacios-González, César; Harris, John

    2016-04-01

    It seems natural to think that the same prudential and ethical reasons for mutual respect and tolerance that one has vis-à-vis other human persons would hold toward newly encountered paradigmatic but nonhuman biological persons. One also tends to think that they would have similar reasons for treating we humans as creatures that count morally in our own right. This line of thought transcends biological boundaries-namely, with regard to artificially (super)intelligent persons-but is this a safe assumption? The issue concerns ultimate moral significance: the significance possessed by human persons, persons from other planets, and hypothetical nonorganic persons in the form of artificial intelligence (AI). This article investigates why our possible relations to AI persons could be more complicated than they first might appear, given that they might possess a radically different nature to us, to the point that civilized or peaceful coexistence in a determinate geographical space could be impossible to achieve.

  19. Artificial intelligence

    OpenAIRE

    Duda, Antonín

    2009-01-01

    Abstract : Issue of this work is to acquaint the reader with the history of artificial inteligence, esspecialy branch of chess computing. Main attention is given to progress from fifties to the present. The work also deals with fighting chess programs against each other, and against human opponents. The greatest attention is focused on 1997 and duel Garry Kasparov against chess program Deep Blue. The work is divided into chapters according to chronological order.

  20. Artificial heart

    Energy Technology Data Exchange (ETDEWEB)

    1984-10-18

    Super-pure plutonium-238 could use heat produced during fission to power an implanted artificial heart. Three model hearts have worked for some time. Concern that excess heat would make the procedure unsafe for humans has broadened the search for another energy source, such as electrohydraulic drive or an external power battery. A back pack approach may provide an interim solution until materials are developed which can withstand heart activity and be small enough for implantation.

  1. Exposure to 56Fe irradiation accelerates normal brain aging and produces deficits in spatial learning and memory

    Science.gov (United States)

    Shukitt-Hale, Barbara; Casadesus, Gemma; Carey, Amanda N.; Rabin, Bernard M.; Joseph, James A.

    Previous studies have shown that radiation exposure, particularly to particles of high energy and charge (HZE particles) such as 56Fe, produces deficits in spatial learning and memory. These adverse behavioral effects are similar to those seen in aged animals. It is possible that these shared effects may be produced by the same mechanism. For example, an increased release of reactive oxygen species, and the subsequent oxidative stress and inflammatory damage caused to the central nervous system, is likely responsible for the deficits seen in aging and following irradiation. Therefore, dietary antioxidants, such as those found in fruits and vegetables, could be used as countermeasures to prevent the behavioral changes seen in these conditions. Both aged and irradiated rats display cognitive impairment in tests of spatial learning and memory such as the Morris water maze and the radial arm maze. These rats have decrements in the ability to build spatial representations of the environment, and they utilize non-spatial strategies to solve tasks. Furthermore, they show a lack of spatial preference, due to a decline in the ability to process or retain place (position of a goal with reference to a “map” provided by the configuration of numerous cues in the environment) information. These declines in spatial memory occur in measures dependent on both reference and working memory, and in the flexibility to reset mental images. These results show that irradiation with 56Fe high-energy particles produces age-like decrements in cognitive behavior that may impair the ability of astronauts, particularly middle-aged ones, to perform critical tasks during long-term space travel beyond the magnetosphere.

  2. Plasma accelerators

    International Nuclear Information System (INIS)

    Bingham, R.; Angelis, U. de; Johnston, T.W.

    1991-01-01

    Recently attention has focused on charged particle acceleration in a plasma by a fast, large amplitude, longitudinal electron plasma wave. The plasma beat wave and plasma wakefield accelerators are two efficient ways of producing ultra-high accelerating gradients. Starting with the plasma beat wave accelerator (PBWA) and laser wakefield accelerator (LWFA) schemes and the plasma wakefield accelerator (PWFA) steady progress has been made in theory, simulations and experiments. Computations are presented for the study of LWFA. (author)

  3. Accelerated fetal growth in early pregnancy and risk of severe large-for-gestational-age and macrosomic infant: a cohort study in a low-risk population.

    Science.gov (United States)

    Simic, Marija; Wikström, Anna-Karin; Stephansson, Olof

    2017-10-01

    Our objective was to examine the association between fetal growth in early pregnancy and risk of severe large-for-gestational-age (LGA) and macrosomia at birth in a low-risk population. Cohort study that included 68 771 women with non-anomalous singleton pregnancies, without history of diabetes or hypertension, based on an electronic database on pregnancies and deliveries in Stockholm-Gotland Region, Sweden, 2008-2014. We performed multivariable logistic regression to estimate the association between accelerated fetal growth occurring in the first through early second trimester as measured by ultrasound and LGA and macrosomia at birth. Restricted analyses were performed in the groups without gestational diabetes and with normal body mass index (18.5-24.9 kg/m 2 ). When adjusting for confounders, the odds of having a severely LGA or macrosomic infant were elevated in mothers with fetuses that were at least 7 days larger than expected as compared with mothers without age discrepancy at the second-trimester scan (adjusted odds ratio 1.80; 95% CI 1.23-2.64 and adjusted odds ratio 2.15; 95% CI 1.55-2.98, respectively). Additionally, mothers without gestational diabetes and mothers with normal weight had an elevated risk of having a severely LGA or macrosomic infant when the age discrepancy by second-trimester ultrasound was at least 7 days. In a low-risk population, ultrasound-estimated accelerated fetal growth in early pregnancy was associated with an increased risk of having a severely LGA or macrosomic infant. © 2017 Nordic Federation of Societies of Obstetrics and Gynecology.

  4. Linear Accelerators

    International Nuclear Information System (INIS)

    Vretenar, M

    2014-01-01

    The main features of radio-frequency linear accelerators are introduced, reviewing the different types of accelerating structures and presenting the main characteristics aspects of linac beam dynamics

  5. Thermo-physical stability of fatty acid eutectic mixtures subjected to accelerated aging for thermal energy storage (TES) application

    International Nuclear Information System (INIS)

    Fauzi, Hadi; Metselaar, Hendrik S.C.; Mahlia, T.M.I.; Silakhori, Mahyar

    2014-01-01

    The thermo-physical stability of fatty acids eutectic mixtures subjected to accelerated number of melting/solidification processes has been identified using thermal cycling test in this study. Myristic acid/palmitic acid (MA/PA) (70/30, wt.%) and myristic acid/palmitic acid/sodium stearate (MA/PA/SS) (70/30/5, wt.%) were selected as eutectic phase change materials (PCMs) to evaluate their stability of phase transition temperature, latent heat of fusion, chemical structure, and volume changes after 200, 500, 1000, and 1500 thermal cycles. The thermal properties of each eutectic PCMs measured by differential scanning calorimetric (DSC) indicated the phase transition temperature and latent heat of fusion values of MA/PA/SS has a smallest changes after 1500 thermal cycles than MA/PA eutectic mixture. MA/PA/SS also has a better chemical structure stability and smaller volume change which is 1.2%, compared to MA/PA with a volume change of 1.6% after 1500 cycles. Therefore, it is concluded that the MA/PA/SS eutectic mixture is suitable for use as a phase change material in thermal energy storage (TES) such as solar water heating and solar space heating applications. - Highlights: •The prepared MA/PA and MA/PA/SS were used as eutectic phase change materials (PCM). •Thermo-physical reliability of eutectic PCMs evaluated using a thermal cycling test. •MA/PA/SS has a great thermo-physical stability than MA/PA after 1500 thermal cycles

  6. Dendroclimatic transfer functions revisited: Little Ice Age and Medieval Warm Period summer temperatures reconstructed using artificial neural networks and linear algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Helama, S.; Holopainen, J.; Eronen, M. [Department of Geology, University of Helsinki, (Finland); Makarenko, N.G. [Russian Academy of Sciences, St. Petersburg (Russian Federation). Pulkovo Astronomical Observatory; Karimova, L.M.; Kruglun, O.A. [Institute of Mathematics, Almaty (Kazakhstan); Timonen, M. [Finnish Forest Research Institute, Rovaniemi Research Unit (Finland); Merilaeinen, J. [SAIMA Unit of the Savonlinna Department of Teacher Education, University of Joensuu (Finland)

    2009-07-01

    Tree-rings tell of past climates. To do so, tree-ring chronologies comprising numerous climate-sensitive living-tree and subfossil time-series need to be 'transferred' into palaeoclimate estimates using transfer functions. The purpose of this study is to compare different types of transfer functions, especially linear and nonlinear algorithms. Accordingly, multiple linear regression (MLR), linear scaling (LSC) and artificial neural networks (ANN, nonlinear algorithm) were compared. Transfer functions were built using a regional tree-ring chronology and instrumental temperature observations from Lapland (northern Finland and Sweden). In addition, conventional MLR was compared with a hybrid model whereby climate was reconstructed separately for short- and long-period timescales prior to combining the bands of timescales into a single hybrid model. The fidelity of the different reconstructions was validated against instrumental climate data. The reconstructions by MLR and ANN showed reliable reconstruction capabilities over the instrumental period (AD 1802-1998). LCS failed to reach reasonable verification statistics and did not qualify as a reliable reconstruction: this was due mainly to exaggeration of the low-frequency climatic variance. Over this instrumental period, the reconstructed low-frequency amplitudes of climate variability were rather similar by MLR and ANN. Notably greater differences between the models were found over the actual reconstruction period (AD 802-1801). A marked temperature decline, as reconstructed by MLR, from the Medieval Warm Period (AD 931-1180) to the Little Ice Age (AD 1601-1850), was evident in all the models. This decline was approx. 0.5 C as reconstructed by MLR. Different ANN based palaeotemperatures showed simultaneous cooling of 0.2 to 0.5 C, depending on algorithm. The hybrid MLR did not seem to provide further benefit above conventional MLR in our sample. The robustness of the conventional MLR over the calibration

  7. Investigation of the effects of a seismic event on accelerated aged components and benefits in equipment life extension

    International Nuclear Information System (INIS)

    Rygg, D.E.; Epstein, J.L.

    1985-01-01

    Westinghouse has performed extensive testing to determine the effects of aging on a wide range of components. Additionally, Westinghouse has an extensive data base of nuclear plant equipment and components. This paper presents how the data base of information on plant parts can be analyzed, modified, and managed or tracked to reflect in-plant parts life extension based on actual tests on aging. Such an approach can benefit utility programs for parts inventory, plant operations and plant availability, and can also reduce the costs of parts reordering. Rather than weigh the merits of the positions in this debate, this paper presents the results of a component aging program which simulates from five to twenty years of operation followed by a seismic event and identifies the possible incorporation of this data into a plant data base which offers quick reference and provides other relevant information on the component and equipment. The use of this data as part of a well structured maintenance and surveillance program offers an avenue to resolve this debate in a cost effective manner

  8. Tai Ji Quan for the aging cancer survivor: Mitigating the accelerated development of disability, falls, and cardiovascular disease from cancer treatment

    Directory of Open Access Journals (Sweden)

    Kerri M. Winters-Stone

    2014-03-01

    Full Text Available Currently there are more than 13.7 million cancer survivors living in the U.S., and that figure is projected to increase by 31% in the next decade, adding another 4 million cancer survivors into the healthcare system. Cancer is largely a disease of aging, and the aging of the population will sharply raise the proportion of older cancer survivors, many of whom will be long-term survivors (5+ years post diagnosis. This review will address the potential utility of exercise to address three health problems that are of particular concern for the aging cancer survivor and the healthcare system, i.e., disability, falls, and cardiovascular disease, because the development of these age-related problems may be accelerated by cancer treatment. While there are many different modes of exercise that each produce specific adaptations, Tai Ji Quan may be a particularly suitable strategy to mitigate the development of age- and cancer-treatment-related problems. Based on studies in older adults without cancer, Tai Ji Quan produces musculoskeletal and cardiometabolic adaptations and is more easily performed by older adults due to its low energy cost and slower movement patterns. Since cancer survivors are mostly older, inactive, and often physically limited by the lingering side effects of treatment, they need to engage in safe, practical, and effective modes of exercise. The dearth of published controlled trials examining the efficacy of Tai Ji Quan to mitigate cancer-treatment-related musculoskeletal and cardiovascular side effects points to ample research opportunities to explore the application of this non-Western exercise modality to improve long-term outcomes for aging cancer survivors.

  9. Efeitos do envelhecimento precoce no vigor de sementes de Chorisia speciosa St. Hil. - Bombacaceae Effects of accelerating aging on the seed vigor of Chorisia speciosa St. Hil. - Bombacaceae

    Directory of Open Access Journals (Sweden)

    Silmara Cristina Fanti

    2005-06-01

    Full Text Available O objetivo deste trabalho foi avaliar a influência do envelhecimento precoce no vigor de sementes de paineira (Chorisia speciosa St. Hil. - Bombacaceae. Adotou-se o método da câmara de envelhecimento (45ºC e 100% de umidade relativa, sendo utilizadas para cada período de envelhecimento (0, 24, 48, 72, 96, 120 e 144 horas quatro subamostras de 50 sementes, distribuídas em caixas tipo ";gerbox";. Decorridos os períodos de envelhecimento, as sementes foram submetidas às seguintes avaliações: teste de germinação (27 ºC, teste de condutividade elétrica e avaliação de plântulas. Os resultados foram submetidos à análise de variância e ao teste de Tukey. Nos períodos de 48, 72, 96 e 120 horas de envelhecimento, foram obtidos valores estatisticamente inferiores de porcentagem de germinação em relação ao experimento-controle. A permanência das sementes por 144 horas em câmara de envelhecimento levou à perda total da viabilidade. O decréscimo na germinação foi diretamente proporcional ao aumento na lixiviação eletrolítica dos solutos celulares das sementes. A partir de 72 horas de envelhecimento precoce, detectou-se redução significativa na porcentagem de plântulas emergidas. O período de 72 horas de envelhecimento mostrou-se adequado para ser utilizado em trabalhos futuros de avaliação de vigor de sementes de paineira, pois é possível detectar diferenças significativas, em relação ao experimento-controle (sementes não envelhecidas, dos parâmetros porcentagem de germinação, porcentagem de plântulas emergidas e condutividade elétrica.The aim of this work was to evaluate the effects of accelerated aging on the seed vigor of paineira (Chorisia speciosa St. Hil.- Bombacaceae. The aging chamber technique was used (45ºC and 100% R.U. and four replications of 50 seeds were distributed on gerbox for each aging time (0, 24, 48, 72, 96, 120 and 144h. After the aging periods, the seeds were submitted to germination

  10. Deterioration of the Medial Olivocochlear Efferent System Accelerates Age-Related Hearing Loss in Pax2-Isl1 Transgenic Mice

    Czech Academy of Sciences Publication Activity Database

    Chumak, Tetyana; Bohuslavová, Romana; Mácová, Iva; Dodd, Nicole; Buckiová, Daniela; Fritzsch, B.; Syka, Josef; Pavlínková, Gabriela

    2016-01-01

    Roč. 53, č. 4 (2016), s. 2368-2383 ISSN 0893-7648 R&D Projects: GA ČR(CZ) GA13-07996S; GA MŠk(CZ) ED1.1.00/02.0109; GA MŠk(CZ) EE2.3.30.0020 Institutional support: RVO:68378041 ; RVO:86652036 Keywords : medial olivocochlear efferent system * islet1 transcription factor * age-related hearing loss * outer hair cells Subject RIV: FH - Neurology; EB - Genetics ; Molecular Biology (BTO-N) Impact factor: 6.190, year: 2016

  11. Effective mechanical means of uterine cervix accelerating maturity in pregnant women of first mature age period of different somatotypes

    Directory of Open Access Journals (Sweden)

    Yakovleva О.V.

    2013-03-01

    Full Text Available The purpose is to evaluate the effectiveness of stimulation of delivery in first mature age period of pregnant women mechanically in different somatotypes. Materials and Methods: 658 patients at 38-41 weeks of gestation of the first period of mature age (22-35 years have been considered. Differentiation by somatotypes has been performed by the method of HT Kaarma (1991. All patients of each somatotype have been divided into primiparous (n = 402 and multiparous (n = 256. Preparation for delivery by mechanical means: on the 1 st day it was introduced into the cervical canal for 16 hours, on the 2nd day — Foley catheter for 8-16 hours (before the birth. Results: In multiparous women the application of mechanical preparation of the birth canal has been effective regardless of somatotype. The percentage of operative delivery in mechanical induction has been lower in multiparous women and also not related to somatotype. In nulliparous women of asthenic and normosthenic type greater efficiency of mechanical induction in preparation for delivery has been revealed. In asthenic and pyknictype mechanical induction has been inefficient and therefore has not been recommended for the use. Conclusion: Application of mechanical means of stimulation of delivery in nulliparous pregnant women should be performed according to their somatotype.

  12. Artificial graphites

    International Nuclear Information System (INIS)

    Maire, J.

    1984-01-01

    Artificial graphites are obtained by agglomeration of carbon powders with an organic binder, then by carbonisation at 1000 0 C and graphitization at 2800 0 C. After description of the processes and products, we show how the properties of the various materials lead to the various uses. Using graphite enables us to solve some problems, but it is not sufficient to satisfy all the need of the application. New carbonaceous material open application range. Finally, if some products are becoming obsolete, other ones are being developed in new applications [fr

  13. Accelerator Service

    International Nuclear Information System (INIS)

    Champelovier, Y.; Ferrari, M.; Gardon, A.; Hadinger, G.; Martin, J.; Plantier, A.

    1998-01-01

    Since the cessation of the operation of hydrogen cluster accelerator in July 1996, four electrostatic accelerators were in operation and used by the peri-nuclear teams working in multidisciplinary collaborations. These are the 4 MV Van de Graaff accelerator, 2,5 MV Van de Graaff accelerator, 400 kV ion implanter as well as the 120 kV isotope separator

  14. Particle accelerators and scientific culture

    International Nuclear Information System (INIS)

    Amaldi, U.

    1979-01-01

    A historical review of fifty years of physics around particle accelerators, from the first nuclear reactions produced by beams of artificially accelerated particles to the large multinational projects now under discussion. The aim is to show how the description of natural phenomena has been shaped by advances in theoretical understanding, the development of new techniques, and the characters of men. Large use has been made of quotations from many of the scientists involved. (Auth.)

  15. Particle accelerators and scientific culture

    International Nuclear Information System (INIS)

    Amaldi, U.

    1979-01-01

    A historical review of fifty years of physics around particle accelerators, from the first nuclear reactions produced by beams of artificially accelerated particles to the large multinational projects now under discussion. The aim is to show how our description of natural phenomena has been shaped by advances in theoretical understanding, the development of new techniques, and the characters of men. Large use has been made of quotations from many of the scientists involved. (Auth.)

  16. mTOR signaling plays a critical role in the defects observed in muscle-derived stem/progenitor cells isolated from a murine model of accelerated aging.

    Science.gov (United States)

    Takayama, Koji; Kawakami, Yohei; Lavasani, Mitra; Mu, Xiaodong; Cummins, James H; Yurube, Takashi; Kuroda, Ryosuke; Kurosaka, Masahiro; Fu, Freddie H; Robbins, Paul D; Niedernhofer, Laura J; Huard, Johnny

    2017-07-01

    Mice expressing reduced levels of ERCC1-XPF (Ercc1 -/Δ mice) demonstrate premature onset of age-related changes due to decreased repair of DNA damage. Muscle-derived stem/progenitor cells (MDSPCs) isolated from Ercc1 -/Δ mice have an impaired capacity for cell differentiation. The mammalian target of rapamycin (mTOR) is a critical regulator of cell growth in response to nutrient, hormone, and oxygen levels. Inhibition of the mTOR pathway extends the lifespan of several species. Here, we examined the role of mTOR in regulating the MDSPC dysfunction that occurs with accelerated aging. We show that mTOR signaling pathways are activated in Ercc1 -/Δ MDSPCs compared with wild-type (WT) MDSPCs. Additionally, inhibiting mTOR with rapamycin promoted autophagy and improved the myogenic differentiation capacity of the Ercc1 -/Δ MDSPCs. The percent of apoptotic and senescent cells in Ercc1 -/Δ MDSPC cultures was decreased upon mTOR inhibition. These results establish that mTOR signaling contributes to stem cell dysfunction and cell fate decisions in response to endogenous DNA damage. Therefore, mTOR represents a potential therapeutic target for improving defective, aged stem cells. © 2016 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 35:1375-1382, 2017. © 2016 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society.

  17. Environmental aging in polycrystalline-Si photovoltaic modules: comparison of chamber-based accelerated degradation studies with field-test data

    Science.gov (United States)

    Lai, T.; Biggie, R.; Brooks, A.; Potter, B. G.; Simmons-Potter, K.

    2015-09-01

    Lifecycle degradation testing of photovoltaic (PV) modules in accelerated-degradation chambers can enable the prediction both of PV performance lifetimes and of return-on-investment for installations of PV systems. With degradation results strongly dependent on chamber test parameters, the validity of such studies relative to fielded, installed PV systems must be determined. In the present work, accelerated aging of a 250 W polycrystalline silicon module is compared to real-time performance degradation in a similar polycrystalline-silicon, fielded, PV technology that has been operating since October 2013. Investigation of environmental aging effects are performed in a full-scale, industrial-standard environmental chamber equipped with single-sun irradiance capability providing illumination uniformity of 98% over a 2 x 1.6 m area. Time-dependent, photovoltaic performance (J-V) is evaluated over a recurring, compressed night-day cycle providing representative local daily solar insolation for the southwestern United States, followed by dark (night) cycling. This cycle is synchronized with thermal and humidity environmental variations that are designed to mimic, as closely as possible, test-yard conditions specific to a 12 month weather profile for a fielded system in Tucson, AZ. Results confirm the impact of environmental conditions on the module long-term performance. While the effects of temperature de-rating can be clearly seen in the data, removal of these effects enables the clear interpretation of module efficiency degradation with time and environmental exposure. With the temperature-dependent effect removed, the normalized efficiency is computed and compared to performance results from another panel of similar technology that has previously experienced identical climate changes in the test yard. Analysis of relative PV module efficiency degradation for the chamber-tested system shows good comparison to the field-tested system with ~2.5% degradation following

  18. Artificial Enzymes, "Chemzymes"

    DEFF Research Database (Denmark)

    Bjerre, Jeannette; Rousseau, Cyril Andre Raphaël; Pedersen, Lavinia Georgeta M

    2008-01-01

    Enzymes have fascinated scientists since their discovery and, over some decades, one aim in organic chemistry has been the creation of molecules that mimic the active sites of enzymes and promote catalysis. Nevertheless, even today, there are relatively few examples of enzyme models that successf......Enzymes have fascinated scientists since their discovery and, over some decades, one aim in organic chemistry has been the creation of molecules that mimic the active sites of enzymes and promote catalysis. Nevertheless, even today, there are relatively few examples of enzyme models...... that successfully perform Michaelis-Menten catalysis under enzymatic conditions (i.e., aqueous medium, neutral pH, ambient temperature) and for those that do, very high rate accelerations are seldomly seen. This review will provide a brief summary of the recent developments in artificial enzymes, so called...... "Chemzymes", based on cyclodextrins and other molecules. Only the chemzymes that have shown enzyme-like activity that has been quantified by different methods will be mentioned. This review will summarize the work done in the field of artificial glycosidases, oxidases, epoxidases, and esterases, as well...

  19. Effect of gamma radiation and accelerated aging on the mechanical and thermal behavior of HDPE/HA nano-composites for bone tissue regeneration.

    Science.gov (United States)

    Alothman, Othman Y; Almajhdi, Fahad N; Fouad, H

    2013-09-24

    The replacement of hard tissues demands biocompatible and sometimes bioactive materials with properties similar to those of bone. Nano-composites made of biocompatible polymers and bioactive inorganic nano particles such as HDPE/HA have attracted attention as permanent bone substitutes due to their excellent mechanical properties and biocompatibility. The HDPE/HA nano-composite is prepared using melt blending at different HA loading ratios. For evaluation of the degradation by radiation, gamma rays of 35 kGy, and 70 kGy were used to irradiate the samples at room temperature in vacuum. The effects of accelerated ageing after gamma irradiation on morphological, mechanical and thermal properties of HDPE/HA nano-composites were measured. In Vitro test results showed that the HDPE and all HDPE/HA nano-composites do not exhibit any cytotoxicity to WISH cell line. The results also indicated that the tensile properties of HDPE/HA nano-composite increased with increasing the HA content except fracture strain decreased. The dynamic mechanical analysis (DMA) results showed that the storage and loss moduli increased with increasing the HA ratio and the testing frequency. Finally, it is remarked that all properties of HDPE/HA is dependent on the irradiation dose and accelerated aging. Based on the experimental results, it is found that the addition of 10%, 20% and 30% HA increases the HDPE stiffness by 23%, 44 and 59% respectively. At the same time, the G' increased from 2.25E11 MPa for neat HDPE to 4.7E11 MPa when 30% HA was added to the polymer matrix. Also, significant improvements in these properties have been observed due to irradiation. Finally, the overall properties of HDPE and its nano-composite properties significantly decreased due to aging and should be taken into consideration in the design of bone substitutes. It is attributed that the developed HDPE/HA nano-composites could be a good alternative material for bone tissue regeneration due to their acceptable

  20. Dynamic mechanical and molecular weight measurements on polymer bonded explosives from thermally accelerated aging tests. III. Kraton block copolymer binder and plasticizers

    International Nuclear Information System (INIS)

    Caley, L.E.; Hoffman, D.M.

    1981-01-01

    The dynamic mechanical properties and molecular weight distribution of two experimental polymer bonded explosives, X-0287 and X-0298, maintained at 23, 60, and 74 0 C for 3 years were examined. X-0287 is 97% 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane explosive, 1.8% Kraton G-1650, and 1.2% B 2 was 170. X-0298 is 97.4% explosive, 1.4% Kraton G-1650, and 1.2% Cenco Hi-vac oil. The relaxation associated with the Kraton rubber block glass transition is observed in both X-0287 and X-0298. In the unaged X-0298 it occurs at -59 0 C and in the aged explosive at 50 0 C. This is caused by migration of the oil plasticizer out of the explosive. In X-0287 the Kraton rubber block T/sub g/ is weak and broad due to the presence of the wax plasticizer. X-0287 has a second broad relaxation associated with the melting of the wax from 10 to 65 0 C. The molecular weight of the Kraton binder decreased with increasing accelerated aging temperature. The oil plasticizer had no stabilizing effect, but below its melting point the wax reduced Kraton chain scission considerably. The simple random chain scission model predicted a 20.5 year use-life for X-0298, but X-0287 was stabilized against degradation below the wax melting point

  1. Future accelerators (?)

    Energy Technology Data Exchange (ETDEWEB)

    John Womersley

    2003-08-21

    I describe the future accelerator facilities that are currently foreseen for electroweak scale physics, neutrino physics, and nuclear structure. I will explore the physics justification for these machines, and suggest how the case for future accelerators can be made.

  2. Supplementation with Lactobacillus plantarum WCFS1 prevents Decline of Mucus Barrier in Colon of Accelerated Aging Ercc1-/Δ7 Mice

    Directory of Open Access Journals (Sweden)

    Adriaan A Van Beek

    2016-10-01

    Full Text Available Although it is clear that probiotics improve intestinal barrier function, little is known about the effects of probiotics on the aging intestine. We investigated effects of 10-wk bacterial supplementation of Lactobacillus plantarum WCFS1, Lactobacillus casei BL23, or Bifidobacterium breve DSM20213 on gut barrier and immunity in 16-week-old accelerated aging Ercc1-/Δ7 mice, which have a median lifespan of ~20wk, and their wild-type littermates. The colonic barrier in Ercc1-/Δ7 mice was characterized by a thin (<10µm mucus layer. L. plantarum prevented this decline in mucus integrity in Ercc1-/Δ7 mice, whereas B. breve exacerbated it. Bacterial supplementations affected the expression of immune-related genes, including Toll-like receptor 4. Regulatory T cell frequencies were increased in the mesenteric lymph nodes of L. plantarum- and L. casei-treated Ercc1-/Δ7 mice. L. plantarum- and L. casei-treated Ercc1-/Δ7 mice showed increased specific antibody production in a T cell-dependent immune response in vivo. By contrast, the effects of bacterial supplementation on wild-type control mice were negligible. Thus, supplementation with L. plantarum – but not with L. casei and B. breve – prevented the decline in the mucus barrier in Ercc1-/Δ7 mice. Our data indicate that age is an important factor influencing beneficial or detrimental effects of candidate probiotics. These findings also highlight the need for caution in translating beneficial effects of probiotics observed in young animals or humans to the elderly.

  3. Envelhecimento acelerado e deterioração controlada em sementes de amendoim Accelerated aging and controlled deterioration of peanut seeds

    Directory of Open Access Journals (Sweden)

    Claudia Antonia Vieira Rossetto

    2004-08-01

    Full Text Available Pesquisas têm sido desenvolvidas visando determinar os procedimentos para a avaliação de diferenças no potencial fisiológico de lotes de sementes, com destaque aos testes de vigor. O objetivo deste trabalho foi estudar o envelhecimento acelerado e a deterioração controlada para avaliação do vigor de sementes de amendoim (Arachis hypogaea. Quatro lotes de sementes de amendoim da cultivar Tatu foram submetidos ao teste de envelhecimento acelerado, em caixas tipo gerbox, com temperatura de 42ºC ou 43ºC, por 48 horas e 72 horas, com e sem o emprego de solução saturada de NaCl, e ao teste de deterioração controlada, com teor de água de 15% e 20%, a 40ºC ou 45ºC, por 48 horas. O teor de água, a germinação e sanidade das sementes foram determinados. Pelos testes de germinação e de emergência, não houve diferença significativa de desempenho entre os quatro lotes. No teste de envelhecimento acelerado com solução salina, o período de 72 horas a 42ºC é suficiente para avaliar o potencial fisiológico das sementes. No teste de deterioração controlada, a combinação de 15% de teor de água nas sementes e 48 horas em banho maria a 45ºC é eficiente para detectar diferenças de vigor entre os lotes.Researches have been developed aiming to determine the procedures for physiological potential seeds evaluation with emphasis to vigour tests. The objective was to study the controlled deterioration and the accelerated aging in peanut (Arachis hypogaea seeds vigour. Four lots of peanut seeds were submitted to the ageing accelerated test, at 42ºC or 43ºC, for 48 hours and 72 hours, with or without the use of saturated solution of NaCl, and controlled deterioration test, with 15% and 20% water content, at 40ºC or 45ºC, for 48 hours. The evaluation of water content, germination and health test was accomplished. There was no different performance among the four lots by the germination and emergency tests. In the ageing accelerated

  4. Influence of aging and growth hormone on different members of the NFkB family and IkB expression in the heart from a murine model of senescence-accelerated aging.

    Science.gov (United States)

    Forman, K; Vara, E; García, C; Kireev, R; Cuesta, S; Acuña-Castroviejo, D; Tresguerres, J A F

    2016-01-01

    Inflammation is related to several pathological processes. The aim of this study was to investigate the protein expression of the different subunits of the nuclear factor Kappa b (NFkBp65, p50, p105, p52, p100) and the protein expressions of IkB beta and alpha in the hearts from a murine model of accelerated aging (SAM model) by Western blot. In addition, the translocation of some isoforms of NFkB from cytosol to nuclei (NFkBp65, p50, p52) and ATP level content was studied. In addition we investigated the effect of the chronic administration of growth hormone (GH) on these age-related parameters. SAMP8 and SAMR1 mice of 2 and 10 months of age were used (n = 30). Animals were divided into five experimental groups: 2 old untreated (SAMP8/SAMR1), 2 young control (SAMP8/SAMR1) and one GH treated-old groups (SAMP8). Age-related changes were found in the studied parameters. We were able to see decreases of ATP level contents and the translocation of the nuclear factor kappa B p50, p52 and p65 from cytosol to nuclei in old SAMP8 mice together with a decrease of IKB proteins. However p100 and p105 did not show differences with aging. No significant changes were recorded in SAMR1 animals. GH treatment showed beneficial effects in old SAMP8 mice inducing an increase in ATP levels and inhibiting the translocation of some NFkB subunits such as p52. Our results supported the relation of NFkB activation with enhanced apoptosis and pro-inflammatory status in old SAMP8 mice and suggested a selective beneficial effect of the GH treatment, which was able to partially reduce the incidence of some deleterious changes in the heart of those mice.

  5. Accelerated aging and seedling field emergence in soybean Envelhecimento acelerado e emergência de plântulas de soja em campo

    Directory of Open Access Journals (Sweden)

    Reynaldo Melo Torres

    2004-10-01

    Full Text Available Information regarding the relationship between laboratory seed vigor testing and seedling field emergence is very important to estimate seed performance after sowing and help producers adopt the best procedures to improve stand establishment. The objective of the present study was to relate accelerated aging (AA test results to soybean [Glycine max (L. Merrill] seedling field emergence results based on data obtained over three agricultural years. The following evaluations were made: seed water content, standard germination, accelerated aging, electrical conductivity, and seedling field emergence. There was a close association between planting environmental conditions, seed physiological quality and seedling field emergence. The most accurate predictions were obtained for AA values > 90%, when field emergence was higher than 80% (r² = 0.90. Based on the results it was concluded that the AA test provided an accurate estimate of field emergence of soybean seedlings. However, as seedbed environmental conditions became less favorable, the ability of the AA test to estimate field performance significantly decreased.Informações sobre a relação entre resultados de testes de vigor conduzidos em laboratório e da emergência de plântulas em campo são fundamentais para a tomada de decisões pelos produtores de sementes. O presente trabalho teve por objetivo verificar a associação entre os resultados do teste de envelhecimento acelerado e a emergência de plântulas de soja [Glycine max (L. Merrill] em campo, em diferentes safras agrícolas e épocas de semeadura. Assim, foram efetuadas as seguintes avaliações: determinação do grau de umidade das sementes; testes de germinação, de envelhecimento acelerado e de condutividade elétrica, bem como emergência de plântulas em campo. A estimativa mais precisa do desempenho das plântulas em campo foi verificada numa faixa de valores de envelhecimento acelerado > 90%, estimando emergência em campo

  6. Age

    Science.gov (United States)

    ... adults? How can you reduce anesthesia risks in older patients? Age Age may bring wisdom but it also brings ... Ask your physician to conduct a pre-surgery cognitive test — an assessment of your mental function. The physician can use the results as a ...

  7. Fate and bioavailability of ¹⁴C-pyrene and ¹⁴C-lindane in sterile natural and artificial soils and the influence of aging.

    Science.gov (United States)

    Smídová, Klára; Hofman, Jakub; Ite, Aniefiok E; Semple, Kirk T

    2012-12-01

    Soil organic matter is used to extrapolate the toxicity and bioavailability of organic pollutants between different soils. However, it has been shown that other factors such as microbial activity are crucial. The aim of this study was to investigate if sterilization can reduce differences in the fate and bioavailability of organic pollutants between different soils. Three natural soils with increasing total organic carbon (TOC) content were collected and three artificial soils were prepared to obtain similar TOCs. Soils were sterilized and spiked with (14)C-pyrene and (14)C-lindane. Total (14)C radioactivity, HPCD extractability, and bioaccumulation in Eisenia fetida were measured over 56 days. When compared to non-sterile soils, differences between the natural and artificial soils and the influence of soil-contaminant contact time were generally reduced in the sterile soils (especially with middle TOC). The results indicate the possibility of using sterile soils as "the worst case scenario" in soil ecotoxicity studies. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Envelhecimento acelerado como teste de vigor para sementes de milho e soja Accelerated aging as test of vigor for corn and soybean seeds

    Directory of Open Access Journals (Sweden)

    Alek Sandro Dutra

    2004-06-01

    control program and the accelerated aging test an important procedure for that. This work was carried out in order to search for specific methodologies of evaluation of seed vigor, in laboratory, based on the accelerated aging test. The research was conducted using six seed lots of corn and soybean species, with commercially accepted quality patterns (germination. The prior established conditions for aging were 42ºC/96h and 45ºC/72h for corn and 41ºC/48 and 72h and 42ºC/48 and 72h for soybean. For each combination of temperature and aging periods, the seeds were placed into plastic boxes (gerbox, with 40mL of distilled water, distributed on the screen, using single layer and based on the seed weight. For the aging, two chamber types, BOD and water jacketed were used. The moisture content and germination of seed lots, after aging, were determined. The water uptake considering the combinations of temperature/exposure period, the two chamber types and the two procedures of determining seed moisture content was higher when the seeds were conditioned in a single layer compared to weight (constant mass. For the corn, the combination of 45ºC/72h with the conditioning of the seeds in only layer was the most efficient method for the separation of the lots with relationship to the vigor. For soybean, the combination 42ºC/48h was more efficient in the separation of the lots, not having interference of the method of conditioning of the seeds, in the screen. Considering the results it can be concluded that the single layer distribution should be used for corn and soybean and the BOD chambers should also be used for accelerated aging test for both species.

  9. Predicting the durability of mineral external plaster using accelerated ageing tests; Prognose der Dauerhaftigkeit mineralischer Aussenputze mit Hilfe von beschleunigten Alterungstests

    Energy Technology Data Exchange (ETDEWEB)

    Bochen, Jerzy; Nowak, Henryk A. [Schlesische Technische Universitaet, Lehrstuhl Bauprozesse, Gliwice (Poland)

    2004-08-01

    This article presents a technique for accelerated ageing tests for different plasters. Two models were developed for describing the durability. The models describe changes in selected characteristics due to frost damage and leaching. The first model is based on changes in mass, the second on changes in strength. The models consider the main characteristics that influence durability, such as strength, porosity, permeability, adhesive tensil strength and aggressive environmental influences. Both models enable the durability of external plaster to be predicted. (Abstract Copyright [2004], Wiley Periodicals, Inc.) [German] Der Beitrag stellt eine Methode fuer beschleunigte Alterungstests von verschiedenen Putzen vor. Fuer die Beschreibung der Dauerhaftigkeit wurden zwei Modelle entwickelt. Die Modelle beschreiben Veraenderungen ausgewaehlter Eigenschaften, die infolge von Frostschaeden und Auslaugung auftreten. Das erste Modell basiert auf der Veraenderung der Masse und das zweite auf der Veraenderung der Festigkeit. In den Modellen werden die wesentlichen Eigenschaften beruecksichtigt, die die Dauerhaftigkeit beeinflussen, wie z. B. Festigkeit, Porositaet, Dichtigkeit, Haftzugfestigkeit und agressive Umwelteinwirkungen. Beide Modelle ermoeglichen die Prognose der Dauerhaftigkeit von Aussenputzen. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

  10. Light-induced alterations of pineapple (Ananas comosus [L.] Merr.) juice volatiles during accelerated ageing and mass spectrometric studies into their precursors.

    Science.gov (United States)

    Steingass, Christof Björn; Glock, Mona Pia; Lieb, Veronika Maria; Carle, Reinhold

    2017-10-01

    Alterations of volatiles during accelerated light-induced ageing of pineapple juice were assessed by HS-SPME-GC-MS in a non-targeted profiling analysis over a 16-week period. Multivariate statistics permitted to reveal substantial chemical markers generally describing the effect of light storage. Volatiles generated comprised phenylpropenes, carbonyls, 2-methylthiophene, toluene, and furfural, while concentrations of methyl and ethyl esters, terpenes, and furanones decreased. In addition, the qualitative composition of phenolic compounds and glycoside-bound volatiles in selected samples was characterized by HPLC-DAD-ESI-MS n as well as HR-ESI-MS. The fresh juice contained unique pineapple metabolites such as S-p-coumaryl, S-coniferyl, S-sinapylglutathione, and structurally related derivatives. Among others, the presence of p-coumaroyl, feruloyl, and caffeoylisocitrate as well as three 4-hydroxy-2,5-dimethyl-3(2H)-furanone glycosides in pineapples could be substantiated by the HR-ESI-MS experiment. Mass spectrometric assignments of selected metabolites are presented, and putative linkages between volatiles and their precursors are established. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. The effect of different acid-treatments on the age spectrum of organic matter in sediments determined by Ramped PyrOx/accelerator mass spectrometry

    Science.gov (United States)

    McNichol, A. P.; Bao, R.

    2016-02-01

    Studies of the radiocarbon and stable carbon isotopes of organic matter (OM) in sediments have become common and are an effective way to understand the fate of sedimentary OM burial in the aquatic environment. In practice, obtaining the radiocarbon and stable carbon isotopic composition in sediments requires first removing inorganic carbon by acid treatment. Two common treatments are acid rinsing and fumigation. The radiocarbon ages and stable carbon isotopic values obtained using the different acid-treatments can differ significantly, but the details of the change of organic components have received much less attention. A new approach was recently developed for radiocarbon dating of carbonate -poor and/or rich sediments using a so-called ramped pyrolysis/oxidation ("Ramped PyrOx") method in combination with accelerator mass spectrometry. Radiocarbon and stable carbon isotopic analysis of the CO2 that evolves under a linear temperature program allows separation of OC components in sediments based on their thermochemical stability (Rosenheim et al., 2008). In this preliminary study, we explore the utility of the Ramped PyrOx method for determining the effect of different acid-treatments on radiocarbon ages and carbon isotopic compositions of OM in sediments. The observations indicate that the HCl rinsing method alters OM more than fumigation in lower carbonate samples while the opposite occurs in the high carbonate samples. This result has implications for studies of the transfer of carbon from the terrestrial to the marine environment because these are samples that contain low amounts of carbonate material. Recommendations for the most appropriate way to treat these samples will be made. The loss of organic matter during the HCl rinsing in the marine carbonate poor sediments could be one of the reasons that radiocarbon ages in the labile thermal fractions were older than that processed by fumigation, whereas younger in the resistant thermal fractions. The distinct

  12. Metodologia alternativa para condução do teste de envelhecimento acelerado em sementes de milho Alternative methodology for the accelerated aging test for corn seeds

    Directory of Open Access Journals (Sweden)

    Sonia Regina Mudrovitsch de Bittencourt

    2012-08-01

    Full Text Available Os testes de vigor são rotineiramente empregados em programas internos de controle de qualidade por empresas sementeiras. Para tanto, é necessária a escolha de métodos eficientes que possibilitem a obtenção de respostas rápidas para a tomada de decisões relacionadas ao manuseio, descarte e comercialização dos lotes de sementes. A pesquisa objetivou verificar a redução do período de execução do teste de envelhecimento acelerado (EA em sementes de milho, empregando-se, para a avaliação do desempenho das sementes após o envelhecimento, o teste de tetrazólio - TZ (viabilidade e vigor em substituição ao de germinação (TG em 10 lotes de sementes de sete genótipos de milho, com e sem tratamento fungicida. Os dados obtidos com a metodologia proposta (EA+TZ foram comparados com os valores determinados pelo teste de envelhecimento acelerado realizado com a metodologia tradicional (EA+TG. O uso do teste de tetrazólio (vigor, associado ao teste de envelhecimento acelerado, possibilitou a obtenção de informações semelhantes às fornecidas pelo teste de germinação empregado para o mesmo fim, reduzindo de oito para três dias o tempo necessário para a obtenção dos resultados em sementes de milho.Some vigor tests are routinely used by seed industry for internal programs of seed quality control. Then, it is requested the use of efficient methods to obtain quick answers to take right decisions related to the management, discard and trade of seed lots. This research was carried out in order to study the possibility to short the period to get the accelerated aging test (AA results, using the tetrazolium test (TZ instead of germination test (GT to evaluate the seed performance after the seed aging. Tem corn seed lots were used, with and without fungicide treatment. The data obtained using the alternative method (AA+TZ were compared with those determined by the traditional one (AA+GT. There was discrimination among seed lots using

  13. Application of a new model for groundwater age distributions: Modeling and isotopic analysis of artificial recharge in the Rialto-Colton basin, California

    Science.gov (United States)

    Ginn, T.R.; Woolfenden, L.

    2002-01-01

    A project for modeling and isotopic analysis of artificial recharge in the Rialto-Colton basin aquifer in California, is discussed. The Rialto-Colton aquifer has been divided into four primary and significant flowpaths following the general direction of groundwater flow from NW to SE. The introductory investigation include sophisticated chemical reaction modeling, with highly simplified flow path simulation. A comprehensive reactive transport model with the established set of geochemical reactions over the whole aquifer will also be developed for treating both reactions and transport realistically. This will be completed by making use of HBGC123D implemented with isotopic calculation step to compute Carbon-14 (C14) and stable Carbon-13 (C13) contents of the water. Computed carbon contents will also be calibrated with the measured carbon contents for assessment of the amount of imported recharge into the Linden pond.

  14. GABA(A receptor-mediated acceleration of aging-associated memory decline in APP/PS1 mice and its pharmacological treatment by picrotoxin.

    Directory of Open Access Journals (Sweden)

    Yuji Yoshiike

    Full Text Available Advanced age and mutations in the genes encoding amyloid precursor protein (APP and presenilin (PS1 are two serious risk factors for Alzheimer's disease (AD. Finding common pathogenic changes originating from these risks may lead to a new therapeutic strategy. We observed a decline in memory performance and reduction in hippocampal long-term potentiation (LTP in both mature adult (9-15 months transgenic APP/PS1 mice and old (19-25 months non-transgenic (nonTg mice. By contrast, in the presence of bicuculline, a GABA(A receptor antagonist, LTP in adult APP/PS1 mice and old nonTg mice was larger than that in adult nonTg mice. The increased LTP levels in bicuculline-treated slices suggested that GABA(A receptor-mediated inhibition in adult APP/PS1 and old nonTg mice was upregulated. Assuming that enhanced inhibition of LTP mediates memory decline in APP/PS1 mice, we rescued memory deficits in adult APP/PS1 mice by treating them with another GABA(A receptor antagonist, picrotoxin (PTX, at a non-epileptic dose for 10 days. Among the saline vehicle-treated groups, substantially higher levels of synaptic proteins such as GABA(A receptor alpha1 subunit, PSD95, and NR2B were observed in APP/PS1 mice than in nonTg control mice. This difference was insignificant among PTX-treated groups, suggesting that memory decline in APP/PS1 mice may result from changes in synaptic protein levels through homeostatic mechanisms. Several independent studies reported previously in aged rodents both an increased level of GABA(A receptor alpha1 subunit and improvement of cognitive functions by long term GABA(A receptor antagonist treatment. Therefore, reduced LTP linked to enhanced GABA(A receptor-mediated inhibition may be triggered by aging and may be accelerated by familial AD-linked gene products like Abeta and mutant PS1, leading to cognitive decline that is pharmacologically treatable at least at this stage of disease progression in mice.