WorldWideScience

Sample records for ph cycling results

  1. Cytoplasmic pH and the regulation of the dictyostelium cell cycle

    NARCIS (Netherlands)

    Aerts, R.J.; Durston, A.J.; Moolenaar, W.H.

    1985-01-01

    Cytoplasmic pH (pHl) was monitored during the cell cycle of synchronous populations of Dictyostelium discoideum by means of a pH “null point” method. There is a cycle of pHl that closely corresponds to the DNA replication cycle, with a minimum of pH 7.20 in interphase and a peak of pH 7.45 during S

  2. Primary water chemistry optimization for extended fuel cycle operation. Results of the 'Duo experimentation' after three cycles

    International Nuclear Information System (INIS)

    Viricel, L.; Andrieu, C.; Segura, J.C.; Rocher, A.; Thomazet, J.; Clinard, M.H.; Dacquait, F.

    2002-01-01

    The primary coolant conditioning in French nuclear power plants is essentially based on the boron-lithium coordinated chemistry, with a target pH of 7.2 at 300 C and a maximum lithium concentration of 2.2 mg/kg. In 1996, EDF 1300 MWe units began operating 18-month fuel cycles, increasing boron concentrations at the beginning of the cycles. Since today the maximum lithium concentration in normal operation is 2.2 mg/kg, extended cycle operation results in a decrease in the pH at the beginning of the cycles, which may possibly lead to deposits in RCS, and particularly on the fuel cladding, and increased dose rates. It has to be noted that today, the fuel assemblies maximum burnup is set at 52 GWd/tU. One solution is to adjust the pH by increasing the lithium content at the beginning of the cycles, which is easy to implement and does not require any modification on the units. Hence, EDF is testing a ''modified'' chemistry regime in the > during 4 fuel cycles, with a maximum authorized lithium content of 3.5 mg/kg at the beginning of the cycles in the Cattenom 2 pilot unit. The Golfech 1 reference unit implements a standard boron-lithium coordination pH 300 7.2. The major goal of the experimentation is to assess the impact of elevated lithium concentrations at the beginning of the cycles on fuel cladding oxide behavior, mass transport and dose rates. This paper presents the results of the first three cycles of the Duo experimentation. (author)

  3. Effects of pH on the life cycle of the midge Tanytansus dissimilis

    Energy Technology Data Exchange (ETDEWEB)

    Bell, H L

    1970-01-01

    All stages of the life cycle of the midge Tanytarsus (paratanytarsus) dissimilis joh. were subjected to low pH and the exremes of tolerance were determined. The life cycle could not be completed below a pH of 5.5.

  4. Fluorine uptake into human enamel around fluoride-containing dental materials during cariogenic pH cycling

    Energy Technology Data Exchange (ETDEWEB)

    Komatsu, H. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan)], E-mail: kom@den.hokudai.ac.jp; Yamamoto, H. [Graduate School of Dentistry, Osaka University, 1-8 Yamada-Oka, Suita 565-0871 (Japan); Nomachi, M. [Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka 560-0043 (Japan); Yasuda, K. [The Wakasa wan Energy Research Center, 64-52-1 Hase, Tsuruga 914-0192 (Japan); Matsuda, Y.; Kinugawa, M.; Kijimura, T.; Sano, H. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan); Satou, T.; Oikawa, S.; Kamiya, T. [Advanced Radiation Technology, TARRI, JAEA, 1233 Watanuki-machi, Takasaki 370-1292 (Japan)

    2009-06-15

    Using PIGE (Proton Induced Gamma Emission) technique at TARRI (Takasaki Advanced Radiation Research Institute), Japan, we measured fluorine (F) uptake into the tooth enamel around two fluoride-containing materials during caries progression using pH cycling. Class V cavities in extracted human teeth were drilled and filled with fluoride-containing materials (i.e. 'Fuji IX' (FN) and 'UniFil flow with MEGA bond' (UF)) and a non-fluoride-containing material (i.e. 'SOLARE with MEGA bond' (SO)). Three 120 {mu}m longitudinal sections including the filling material were obtained from each tooth. In order to simulate daily acid attack occurring in the oral cavity, the pH cycling (pH 6.8-4.5) was carried out for 1, 3 and 5 weeks, separately. After pH cycling, the caries progression in all specimens was observed using transverse microradiography (TMR). The F and calcium distributions of the specimens were evaluated using PIGE and PIXE techniques. The F distribution of the specimens clearly showed the F uptake from FN into enamel adjacent to the filling material, while the F uptakes from UF and SO were not detected. For UF, the MEGA bond (non-fluoride-containing) between the tooth and UniFil flow interfered with the F absorption into the tooth. For FN, the amount of F uptake into the subsurface enamel increased during pH cycling. The amount of F uptake in 5-week pH cycling had significantly higher value compared to those in 1- and 3-week pH cycling. For UF and SO, there were no significant differences between the different durations of pH cycling. Among fluoride-containing materials, there were some differences in the F uptake with increased pH cycling, which could possibly lead to obtaining difference in clinical performance. The data obtained using PIGE and PIXE techniques were useful in understanding the benefit of fluorine by means of fluoride-containing material for preventing caries.

  5. Fluorine uptake into human enamel around fluoride-containing dental materials during cariogenic pH cycling

    International Nuclear Information System (INIS)

    Komatsu, H.; Yamamoto, H.; Nomachi, M.; Yasuda, K.; Matsuda, Y.; Kinugawa, M.; Kijimura, T.; Sano, H.; Satou, T.; Oikawa, S.; Kamiya, T.

    2009-01-01

    Using PIGE (Proton Induced Gamma Emission) technique at TARRI (Takasaki Advanced Radiation Research Institute), Japan, we measured fluorine (F) uptake into the tooth enamel around two fluoride-containing materials during caries progression using pH cycling. Class V cavities in extracted human teeth were drilled and filled with fluoride-containing materials (i.e. 'Fuji IX' (FN) and 'UniFil flow with MEGA bond' (UF)) and a non-fluoride-containing material (i.e. 'SOLARE with MEGA bond' (SO)). Three 120 μm longitudinal sections including the filling material were obtained from each tooth. In order to simulate daily acid attack occurring in the oral cavity, the pH cycling (pH 6.8-4.5) was carried out for 1, 3 and 5 weeks, separately. After pH cycling, the caries progression in all specimens was observed using transverse microradiography (TMR). The F and calcium distributions of the specimens were evaluated using PIGE and PIXE techniques. The F distribution of the specimens clearly showed the F uptake from FN into enamel adjacent to the filling material, while the F uptakes from UF and SO were not detected. For UF, the MEGA bond (non-fluoride-containing) between the tooth and UniFil flow interfered with the F absorption into the tooth. For FN, the amount of F uptake into the subsurface enamel increased during pH cycling. The amount of F uptake in 5-week pH cycling had significantly higher value compared to those in 1- and 3-week pH cycling. For UF and SO, there were no significant differences between the different durations of pH cycling. Among fluoride-containing materials, there were some differences in the F uptake with increased pH cycling, which could possibly lead to obtaining difference in clinical performance. The data obtained using PIGE and PIXE techniques were useful in understanding the benefit of fluorine by means of fluoride-containing material for preventing caries.

  6. Fluorine uptake into human enamel around a fluoride-containing dental material during cariogenic pH cycling

    International Nuclear Information System (INIS)

    Komatsu, H.; Yamamoto, H.; Nomachi, M.; Yasuda, K.; Matsuda, Y.; Murata, Y.; Kijimura, T.; Sano, H.; Sakai, T.; Kamiya, T.

    2007-01-01

    Using PIGE (TIARA, JAPAN) technique, we measured fluorine (F) uptake into the tooth enamel around a fluoride-containing material during caries progression using pH cycling. Class I cavities in the buccal surfaces of 6 extracted human teeth were drilled and filled with fluoride-containing material; a glass ionomer cement (Fuji IX(GC)). Three 300 μm sections through the material were obtained from each tooth. Two of these specimens were utilized to measure the F distribution in enamel adjacent to the material. A 1.7 MeV proton beam accelerated by the TIARA single-ended accelerator was delivered to a micro-beam apparatus. The beam spot size was about 1 μm with a beam current of about 100 pA. A nuclear reaction, 19 F(p, αγ) 16 0, was used to measure the F concentration and the gamma-rays from this reaction were detected with a 4' NaI detector. X-rays induced by proton were detected with a Si(Li) detector to measure calcium concentration and the beam intensity was monitored with the X-ray yield from a copper foil for quantitative analysis. After measurement of F uptake, all specimens were polished to a thickness of 120 μm. In order to simulate daily acid challenges occurring in the oral cavity, the pH cycling (pH6.8-pH4.5) was carried out for 1, 3 and 5 weeks, separately. The duration that the solution remained below pH 5.5 was 37 min per cycle. The cycles were repeated 6 times per day with 2 h interval between cycles, and the specimens were kept in remineralizing solution for the rest of pH cycle. After pH cycling, F and calcium distribution of each specimen was evaluated using PIGE technique. The F distribution of the specimens before pH cycling clearly showed the F uptake from fluoride-containing material into enamel adjacent to the material. After pH cycling, the caries progression in all specimens was observed by the image of transverse microradiography (TMR). The depth of caries and mineral loss progressed with increasing the duration of pH cycling, although

  7. Fluorine uptake into human enamel around a fluoride-containing dental material during cariogenic pH cycling

    Energy Technology Data Exchange (ETDEWEB)

    Komatsu, H. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan)]. E-mail: kom@den.hokudai.ac.jp; Yamamoto, H. [Graduate School of Dentistry, Osaka University, 1-8 Yamada-Oka, Suita 565-0871 (Japan); Nomachi, M. [Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka 560-0043 (Japan); Yasuda, K. [Wakasa wan Energy Research Center, 64-52-1 Hase, Tsuruga 914-0192 (Japan); Matsuda, Y. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan); Murata, Y. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan); Kijimura, T. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan); Sano, H. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan); Sakai, T. [Takasaki Advanced Radiation Research Institute, JAEA, 1233 Watanuki-machi, Takasaki 370-1292 (Japan); Kamiya, T. [Takasaki Advanced Radiation Research Institute, JAEA, 1233 Watanuki-machi, Takasaki 370-1292 (Japan)

    2007-07-15

    Using PIGE (TIARA, JAPAN) technique, we measured fluorine (F) uptake into the tooth enamel around a fluoride-containing material during caries progression using pH cycling. Class I cavities in the buccal surfaces of 6 extracted human teeth were drilled and filled with fluoride-containing material; a glass ionomer cement (Fuji IX(GC)). Three 300 {mu}m sections through the material were obtained from each tooth. Two of these specimens were utilized to measure the F distribution in enamel adjacent to the material. A 1.7 MeV proton beam accelerated by the TIARA single-ended accelerator was delivered to a micro-beam apparatus. The beam spot size was about 1 {mu}m with a beam current of about 100 pA. A nuclear reaction, {sup 19}F(p, {alpha}{gamma}){sup 16}0, was used to measure the F concentration and the gamma-rays from this reaction were detected with a 4' NaI detector. X-rays induced by proton were detected with a Si(Li) detector to measure calcium concentration and the beam intensity was monitored with the X-ray yield from a copper foil for quantitative analysis. After measurement of F uptake, all specimens were polished to a thickness of 120 {mu}m. In order to simulate daily acid challenges occurring in the oral cavity, the pH cycling (pH6.8-pH4.5) was carried out for 1, 3 and 5 weeks, separately. The duration that the solution remained below pH 5.5 was 37 min per cycle. The cycles were repeated 6 times per day with 2 h interval between cycles, and the specimens were kept in remineralizing solution for the rest of pH cycle. After pH cycling, F and calcium distribution of each specimen was evaluated using PIGE technique. The F distribution of the specimens before pH cycling clearly showed the F uptake from fluoride-containing material into enamel adjacent to the material. After pH cycling, the caries progression in all specimens was observed by the image of transverse microradiography (TMR). The depth of caries and mineral loss progressed with increasing the

  8. Primary water chemistry optimization for extended fuel cycle operation. Results of the 'Duo experimentation' after three cycles

    Energy Technology Data Exchange (ETDEWEB)

    Viricel, L.; Andrieu, C.; Segura, J.C.; Rocher, A. [Electricite de France (France); Thomazet, J.; Clinard, M.H. [Framatome ANP (France); Dacquait, F. [Commissariat a l' Energie Atomique (France)

    2002-07-01

    The primary coolant conditioning in French nuclear power plants is essentially based on the boron-lithium coordinated chemistry, with a target pH of 7.2 at 300 C and a maximum lithium concentration of 2.2 mg/kg. In 1996, EDF 1300 MWe units began operating 18-month fuel cycles, increasing boron concentrations at the beginning of the cycles. Since today the maximum lithium concentration in normal operation is 2.2 mg/kg, extended cycle operation results in a decrease in the pH at the beginning of the cycles, which may possibly lead to deposits in RCS, and particularly on the fuel cladding, and increased dose rates. It has to be noted that today, the fuel assemblies maximum burnup is set at 52 GWd/tU. One solution is to adjust the pH by increasing the lithium content at the beginning of the cycles, which is easy to implement and does not require any modification on the units. Hence, EDF is testing a ''modified'' chemistry regime in the << Duo experimentation >> during 4 fuel cycles, with a maximum authorized lithium content of 3.5 mg/kg at the beginning of the cycles in the Cattenom 2 pilot unit. The Golfech 1 reference unit implements a standard boron-lithium coordination pH{sub 300} 7.2. The major goal of the experimentation is to assess the impact of elevated lithium concentrations at the beginning of the cycles on fuel cladding oxide behavior, mass transport and dose rates. This paper presents the results of the first three cycles of the Duo experimentation. (author)

  9. Integration and validation testing for PhEDEx, DBS and DAS with the PhEDEx LifeCycle agent

    CERN Document Server

    Wildish, Anthony

    2013-01-01

    The ever-increasing amount of data handled by the CMS dataflow and workflow management tools poses new challenges for cross-validation among different systems within CMS experiment at LHC. To approach this problem we developed an integration test suite based on the LifeCycle agent, a tool originally conceived for stress-testing new releases of PhEDEx, the CMS data-placement tool. The LifeCycle agent provides a framework for customising the test workflow in arbitrary ways, and can scale to levels of activity well beyond those seen in normal running. This means we can run realistic performance tests at scales not likely to be seen by the experiment for some years, or with custom topologies to examine particular situations that may cause concern some time in the future.The LifeCycle agent has recently been enhanced to become a general purpose integration and validation testing tool for major CMS services (PhEDEx, DBS, DAS). It allows cross-system integration tests of all three components to be performed in contr...

  10. Oxidation of tartrazine with ultraviolet light emitting diodes: pH and duty cycles effects.

    Science.gov (United States)

    Stewart, Brandon M; Miller, Michael E; Kempisty, David M; Stubbs, John; Harper, Willie F

    2018-03-01

    The presence of tartrazine (TAR) in the water cycle poses serious threats to human health. This study investigated the used of light emitting diodes (LEDs) in the advanced oxidation of TAR under different pH and duty cycle (DC) conditions. The first order reaction rate constant for TAR oxidation was positively correlated with DC, negatively correlated with pH, and typically greatest at pH 6. Chemical byproduct analysis indicated that OH addition, H abstraction, and electron transfer without molecule transfer were among the relevant reaction mechanisms for TAR degradation. Six byproducts were identified, four were reported for the first time, and two demonstrated that TAR rings were cleaved. This research is the first to determine the optimal pH for UVLED-driven oxidation of TAR and the first to identify new TAR-related byproducts from UVLED-based water treatment.

  11. Fluorine uptake into the human enamel surface from fluoride-containing sealing materials during cariogenic pH cycling

    Science.gov (United States)

    Yasuhiro, Matsuda; Katsushi, Okuyama; Hiroko, Yamamoto; Hisanori, Komatsu; Masashi, Koka; Takahiro, Sato; Naoki, Hashimoto; Saiko, Oki; Chiharu, Kawamoto; Hidehiko, Sano

    2015-04-01

    To prevent the formation of caries and reduce dentin hypersensitivity, sealing materials, either with or without fluoride, are generally applied on the tooth in clinical practice. Application of fluoride-free sealing materials results in the formation of an acid-resistant layer on the tooth surface. On the other hand, fluoride-containing sealing materials might not only form an acid-resistant layer but could possibly further provide fluoride to enhance remineralization and reduce demineralization. In this study, the demineralization prevention ability and fluorine uptake rate in human enamel of fluoride-containing sealing materials ["MS coats F" (MSF)] and fluoride-free sealing materials ("hybrid coats 2" [HI]) were evaluated using an automatic pH cycling system. Each material was applied to the original tooth surface, the cut surfaces were covered with sticky wax, and the automatic pH-cycling system simulated daily acid changes (pH 6.8-4.5) occurring in the oral cavity for 4 weeks. Caries progression was analyzed using transverse microradiography (TMR) taken pre and post the 4 weeks of pH cycling. The fluorine and calcium distributions in the carious lesion in each specimen were evaluated using the proton-induced gamma emission (PIGE) and proton-induced X-ray (PIXE) techniques, respectively. TMR analysis showed that both MSF and HI had a caries-preventing effect after 4 weeks of pH cycling. PIGE/PIXE analysis demonstrated that only MSF resulted in fluoride uptake in the enamel surface. Therefore, MSF can help to form an acid-resistant layer and provide fluoride to the enamel surface. The presence of fluoride on the enamel surface suggested that MSF could prevent demineralization, even if the acid-resistant layer was removed, in clinical settings. The data obtained using the PIGE and PIXE techniques are useful for understanding the benefits of the use of a fluoride-containing sealing material for preventing caries.

  12. Influence of pH, light cycle, and temperature on ecotoxicity of four sulfonylurea herbicides towards Lemna gibba

    DEFF Research Database (Denmark)

    Rosenkrantz, Rikke Tjørnhøj; Cedergreen, Nina; Baun, Anders

    2013-01-01

    test conditions on the toxicity of four sulfonylurea herbicides (SUs). The toxicity of the four SUs towards Lemna gibba was investigated at three pH levels (6, 7.5 and 9), at two temperatures (15 and 24 °C) and two light regimes (continuous and 12:12 h light:dark cycle) The EC50 increased twofold...... conditions e.g. specific temperature, pH, light intensity etc. However, environmental conditions under which the organisms live are rarely identical to the standard conditions. Thus, the ecotoxicity of compounds found in standard test is not only a function of the compounds inherent physico...... to tenfold for the four SUs when pH was increased from 6 to 9. Decreasing the temperature from 24 to 15 °C or introducing a dark:light cycle did not cause any trends in changes in toxicity. The results show that test conditions can have an effect on the toxicity and this should be considered when...

  13. Fluorine uptake into the human enamel surface from fluoride-containing sealing materials during cariogenic pH cycling

    Energy Technology Data Exchange (ETDEWEB)

    Yasuhiro, Matsuda, E-mail: matsuda@den.hokudai.ac.jp [Department of Restorative Dentistry, Graduate School of Dental Medicine Hokkaido University (Japan); Katsushi, Okuyama [Department of Restorative Dentistry, Graduate School of Dental Medicine Hokkaido University (Japan); Hiroko, Yamamoto [Graduate School of Dentistry, Osaka University (Japan); Hisanori, Komatsu [Department of Restorative Dentistry, Graduate School of Dental Medicine Hokkaido University (Japan); Masashi, Koka; Takahiro, Sato [Takasaki Advanced Radiation Research Institute, JAEA (Japan); Naoki, Hashimoto; Saiko, Oki; Chiharu, Kawamoto; Hidehiko, Sano [Department of Restorative Dentistry, Graduate School of Dental Medicine Hokkaido University (Japan)

    2015-04-01

    To prevent the formation of caries and reduce dentin hypersensitivity, sealing materials, either with or without fluoride, are generally applied on the tooth in clinical practice. Application of fluoride-free sealing materials results in the formation of an acid-resistant layer on the tooth surface. On the other hand, fluoride-containing sealing materials might not only form an acid-resistant layer but could possibly further provide fluoride to enhance remineralization and reduce demineralization. In this study, the demineralization prevention ability and fluorine uptake rate in human enamel of fluoride-containing sealing materials [“MS coats F” (MSF)] and fluoride-free sealing materials (“hybrid coats 2” [HI]) were evaluated using an automatic pH cycling system. Each material was applied to the original tooth surface, the cut surfaces were covered with sticky wax, and the automatic pH-cycling system simulated daily acid changes (pH 6.8–4.5) occurring in the oral cavity for 4 weeks. Caries progression was analyzed using transverse microradiography (TMR) taken pre and post the 4 weeks of pH cycling. The fluorine and calcium distributions in the carious lesion in each specimen were evaluated using the proton-induced gamma emission (PIGE) and proton-induced X-ray (PIXE) techniques, respectively. TMR analysis showed that both MSF and HI had a caries-preventing effect after 4 weeks of pH cycling. PIGE/PIXE analysis demonstrated that only MSF resulted in fluoride uptake in the enamel surface. Therefore, MSF can help to form an acid-resistant layer and provide fluoride to the enamel surface. The presence of fluoride on the enamel surface suggested that MSF could prevent demineralization, even if the acid-resistant layer was removed, in clinical settings. The data obtained using the PIGE and PIXE techniques are useful for understanding the benefits of the use of a fluoride-containing sealing material for preventing caries.

  14. Fluorine uptake into the human enamel surface from fluoride-containing sealing materials during cariogenic pH cycling

    International Nuclear Information System (INIS)

    Yasuhiro, Matsuda; Katsushi, Okuyama; Hiroko, Yamamoto; Hisanori, Komatsu; Masashi, Koka; Takahiro, Sato; Naoki, Hashimoto; Saiko, Oki; Chiharu, Kawamoto; Hidehiko, Sano

    2015-01-01

    To prevent the formation of caries and reduce dentin hypersensitivity, sealing materials, either with or without fluoride, are generally applied on the tooth in clinical practice. Application of fluoride-free sealing materials results in the formation of an acid-resistant layer on the tooth surface. On the other hand, fluoride-containing sealing materials might not only form an acid-resistant layer but could possibly further provide fluoride to enhance remineralization and reduce demineralization. In this study, the demineralization prevention ability and fluorine uptake rate in human enamel of fluoride-containing sealing materials [“MS coats F” (MSF)] and fluoride-free sealing materials (“hybrid coats 2” [HI]) were evaluated using an automatic pH cycling system. Each material was applied to the original tooth surface, the cut surfaces were covered with sticky wax, and the automatic pH-cycling system simulated daily acid changes (pH 6.8–4.5) occurring in the oral cavity for 4 weeks. Caries progression was analyzed using transverse microradiography (TMR) taken pre and post the 4 weeks of pH cycling. The fluorine and calcium distributions in the carious lesion in each specimen were evaluated using the proton-induced gamma emission (PIGE) and proton-induced X-ray (PIXE) techniques, respectively. TMR analysis showed that both MSF and HI had a caries-preventing effect after 4 weeks of pH cycling. PIGE/PIXE analysis demonstrated that only MSF resulted in fluoride uptake in the enamel surface. Therefore, MSF can help to form an acid-resistant layer and provide fluoride to the enamel surface. The presence of fluoride on the enamel surface suggested that MSF could prevent demineralization, even if the acid-resistant layer was removed, in clinical settings. The data obtained using the PIGE and PIXE techniques are useful for understanding the benefits of the use of a fluoride-containing sealing material for preventing caries

  15. Update to Millstone 3 elevated pH tests

    Energy Technology Data Exchange (ETDEWEB)

    Bergmann, C.A.; Perock, J.D. [Westinghouse Electric Corp., Pittsburgh, PA (United States); Hudson, M.J.B.; King, R.W.; Macklin, S. [Northeast Utilities, Hartford, CT (United States)

    1995-03-01

    In view of the potential radiological benefits of elevated coolant pH operation, Northwest Utilities (NU), in support of an EPRI-Westinghouse program, agreed to operate the Millstone 3 plant at the start of its second fuel cycle as a demonstration of the effect of elevated coolant pH on out-of-core radiation fields. Operating with an elevated pH is defined as operating with an average lithium concentration of 3.35 ppm, until reaching an end of cycle pH of 7.2 or 7.4. The plant operated during its second and third cycles with an elevated coolant pH. The end of cycle pH during the second cycle was 7.4, and 7.2 during the third cycle. (During the first cycle, operation was with a coordinated pH of 7.0). Evaluation of the dose rate trends in Millstone 3 after two cycles of elevated coolant pH operation concluded that an elevated coolant pH resulted in a 15 percent lower component dose rate compared to other plants that operated with coordinated pH 6.9. However, due to a possible increase in fuel clad corrosion, operation during cycle 4 was restricted to pH 6.9 coordinated chemistry, with the exception of the last two months during which the pH increased to 7.35. At the end of cycle 4 (EOC4), there was a greater increase in component and crud trap dose rates than expected. This paper reviews the radiological trends in the plant and discusses the potential causes for the increase in the dose rates at EOC4.

  16. Integration and validation testing for PhEDEx, DBS and DAS with the PhEDEx LifeCycle agent

    International Nuclear Information System (INIS)

    Boeser, C; Chwalek, T; Giffels, M; Kuznetsov, V; Wildish, T

    2014-01-01

    The ever-increasing amount of data handled by the CMS dataflow and workflow management tools poses new challenges for cross-validation among different systems within CMS experiment at LHC. To approach this problem we developed an integration test suite based on the LifeCycle agent, a tool originally conceived for stress-testing new releases of PhEDEx, the CMS data-placement tool. The LifeCycle agent provides a framework for customising the test workflow in arbitrary ways, and can scale to levels of activity well beyond those seen in normal running. This means we can run realistic performance tests at scales not likely to be seen by the experiment for some years, or with custom topologies to examine particular situations that may cause concern some time in the future. The LifeCycle agent has recently been enhanced to become a general purpose integration and validation testing tool for major CMS services. It allows cross-system integration tests of all three components to be performed in controlled environments, without interfering with production services. In this paper we discuss the design and implementation of the LifeCycle agent. We describe how it is used for small-scale debugging and validation tests, and how we extend that to large-scale tests of whole groups of sub-systems. We show how the LifeCycle agent can emulate the action of operators, physicists, or software agents external to the system under test, and how it can be scaled to large and complex systems.

  17. Integration and validation testing for PhEDEx, DBS and DAS with the PhEDEx LifeCycle agent

    Science.gov (United States)

    Boeser, C.; Chwalek, T.; Giffels, M.; Kuznetsov, V.; Wildish, T.

    2014-06-01

    The ever-increasing amount of data handled by the CMS dataflow and workflow management tools poses new challenges for cross-validation among different systems within CMS experiment at LHC. To approach this problem we developed an integration test suite based on the LifeCycle agent, a tool originally conceived for stress-testing new releases of PhEDEx, the CMS data-placement tool. The LifeCycle agent provides a framework for customising the test workflow in arbitrary ways, and can scale to levels of activity well beyond those seen in normal running. This means we can run realistic performance tests at scales not likely to be seen by the experiment for some years, or with custom topologies to examine particular situations that may cause concern some time in the future. The LifeCycle agent has recently been enhanced to become a general purpose integration and validation testing tool for major CMS services. It allows cross-system integration tests of all three components to be performed in controlled environments, without interfering with production services. In this paper we discuss the design and implementation of the LifeCycle agent. We describe how it is used for small-scale debugging and validation tests, and how we extend that to large-scale tests of whole groups of sub-systems. We show how the LifeCycle agent can emulate the action of operators, physicists, or software agents external to the system under test, and how it can be scaled to large and complex systems.

  18. Results from the first cycle of the PWR crud deposition test (IFA-665.1)

    International Nuclear Information System (INIS)

    Bennett, Peter

    2004-03-01

    The main objective of IFA-665.1 is to deposit crud on fuel rods operating under PWR thermal-hydraulic and water chemistry conditions, and to measure the resulting power reduction due to incorporation of boron into the crud. The test has operated for 160 days at power. Water chemistry conditions were 3.15 ppm LiOH and 1400 ppm boron (pH 300 =7.0). The coolant inlet temperature was 290/294 C, with sub-cooled nucleate boiling along the upper half of the fuel bundle. This report presents the results from the first cycle of operation. Three methods have been used to attempt to accelerate crud formation: (i) injection of simulated crud particles (NiFe 2 O 4 ); (ii) pH transients (reduction of pH 300 from 7.0 to 6.0 for periods of 48 hours); and (iii) oxygen addition transients. While the pH transients resulted in movement of large amounts of corrosion products around the loop, no significant deposition onto the fuel surfaces was measured. Comparison of the heat fluxes in IFA-665 with those in previous tests in which crud deposition has occurred does not clearly identify reasons for the lack of crud formation, although it is noted that higher heat fluxes may be required. In addition, the relatively benign boiling conditions in the current test (small void fraction with no detached voidage) may partly explain the absence of crud formation. For the second cycle of the test, changes will be made to the water chemistry to attempt to increase the concentrations of dissolved and colloidal Fe and Ni in the test rig, such that a continuous (Fe + Ni) level of 100 ppb will be targeted, with short-term concentrations of colloids of up to 500 ppb. (Author)

  19. Constraining the climate and ocean pH of the early Earth with a geological carbon cycle model.

    Science.gov (United States)

    Krissansen-Totton, Joshua; Arney, Giada N; Catling, David C

    2018-04-17

    The early Earth's environment is controversial. Climatic estimates range from hot to glacial, and inferred marine pH spans strongly alkaline to acidic. Better understanding of early climate and ocean chemistry would improve our knowledge of the origin of life and its coevolution with the environment. Here, we use a geological carbon cycle model with ocean chemistry to calculate self-consistent histories of climate and ocean pH. Our carbon cycle model includes an empirically justified temperature and pH dependence of seafloor weathering, allowing the relative importance of continental and seafloor weathering to be evaluated. We find that the Archean climate was likely temperate (0-50 °C) due to the combined negative feedbacks of continental and seafloor weathering. Ocean pH evolves monotonically from [Formula: see text] (2σ) at 4.0 Ga to [Formula: see text] (2σ) at the Archean-Proterozoic boundary, and to [Formula: see text] (2σ) at the Proterozoic-Phanerozoic boundary. This evolution is driven by the secular decline of pCO 2 , which in turn is a consequence of increasing solar luminosity, but is moderated by carbonate alkalinity delivered from continental and seafloor weathering. Archean seafloor weathering may have been a comparable carbon sink to continental weathering, but is less dominant than previously assumed, and would not have induced global glaciation. We show how these conclusions are robust to a wide range of scenarios for continental growth, internal heat flow evolution and outgassing history, greenhouse gas abundances, and changes in the biotic enhancement of weathering. Copyright © 2018 the Author(s). Published by PNAS.

  20. Constraining the climate and ocean pH of the early Earth with a geological carbon cycle model

    Science.gov (United States)

    Krissansen-Totton, Joshua; Arney, Giada N.; Catling, David C.

    2018-04-01

    The early Earth’s environment is controversial. Climatic estimates range from hot to glacial, and inferred marine pH spans strongly alkaline to acidic. Better understanding of early climate and ocean chemistry would improve our knowledge of the origin of life and its coevolution with the environment. Here, we use a geological carbon cycle model with ocean chemistry to calculate self-consistent histories of climate and ocean pH. Our carbon cycle model includes an empirically justified temperature and pH dependence of seafloor weathering, allowing the relative importance of continental and seafloor weathering to be evaluated. We find that the Archean climate was likely temperate (0–50 °C) due to the combined negative feedbacks of continental and seafloor weathering. Ocean pH evolves monotonically from 6.6‑0.4+0.6 (2σ) at 4.0 Ga to 7.0‑0.5+0.7 (2σ) at the Archean–Proterozoic boundary, and to 7.9‑0.2+0.1 (2σ) at the Proterozoic–Phanerozoic boundary. This evolution is driven by the secular decline of pCO2, which in turn is a consequence of increasing solar luminosity, but is moderated by carbonate alkalinity delivered from continental and seafloor weathering. Archean seafloor weathering may have been a comparable carbon sink to continental weathering, but is less dominant than previously assumed, and would not have induced global glaciation. We show how these conclusions are robust to a wide range of scenarios for continental growth, internal heat flow evolution and outgassing history, greenhouse gas abundances, and changes in the biotic enhancement of weathering.

  1. Implications for metal and volatile cycles from the pH of subduction zone fluids

    Science.gov (United States)

    Galvez, Matthieu E.; Connolly, James A. D.; Manning, Craig E.

    2016-11-01

    The chemistry of aqueous fluids controls the transport and exchange—the cycles—of metals and volatile elements on Earth. Subduction zones, where oceanic plates sink into the Earth’s interior, are the most important geodynamic setting for this fluid-mediated chemical exchange. Characterizing the ionic speciation and pH of fluids equilibrated with rocks at subduction zone conditions has long been a major challenge in Earth science. Here we report thermodynamic predictions of fluid-rock equilibria that tie together models of the thermal structure, mineralogy and fluid speciation of subduction zones. We find that the pH of fluids in subducted crustal lithologies is confined to a mildly alkaline range, modulated by rock volatile and chlorine contents. Cold subduction typical of the Phanerozoic eon favours the preservation of oxidized carbon in subducting slabs. In contrast, the pH of mantle wedge fluids is very sensitive to minor variations in rock composition. These variations may be caused by intramantle differentiation, or by infiltration of fluids enriched in alkali components extracted from the subducted crust. The sensitivity of pH to soluble elements in low abundance in the host rocks, such as carbon, alkali metals and halogens, illustrates a feedback between the chemistry of the Earth’s atmosphere-ocean system and the speciation of subduction zone fluids via the composition of the seawater-altered oceanic lithosphere. Our findings provide a perspective on the controlling reactions that have coupled metal and volatile cycles in subduction zones for more than 3 billion years7.

  2. Cytological Characteristics of Mucose Cell and Vaginal Temperature and pH During Estrous Cycle in Local Sheep

    Directory of Open Access Journals (Sweden)

    Siti Darodjah Rasad

    2017-09-01

    Full Text Available Aim of this study was to examine the characteristics cytology of mucous cell-,temperature- and pH vagina during estrous cycle in local sheep.  31local sheep were synchronized with vaginal sponge consist of 20  mg  progesterone hormone before carried out observations of cytology of cells from the vaginal mucose through vaginal swabs, temperature and pH of the vagina.  Vaginal swabs were collected daily at 7 am for a weeks.Vaginal temperature and pH measurement is carried out twice a day, at 07.00 am and 15.00 pm for a weeks after vaginal swabs. Smears of the swab were then prepared on glass slide and they were stained with Giemsa.  Vaginal epithelial cells; Parabasal, intermediate and superficial cells were counted and their percentages during pro-estrous, estrous and di-estrous were determined. Di-estrous was characterized by the absent of superficial cells in the epithelial vagina. Pro-estrous was characterized by the increasing progressively of intermediate/superficial cells in epithelial vagina, whereas estrous was characterized by the presence of superficial/cornification cells in most epithelial vagina. Based on the dominance of superficial cell, the number of sheep identified as estrous is highest on third day, with 52%.  Observation on vaginal temperature also resulting that the highest temperature values obtained on the third day of 39,08±0.28°C.  It could be effected of the vaginal pH during the observation. Underthe influence ofestrogen, the epithelial vaginalcellssynthesizeand accumulateglycogenin large quantitiesdepositedin the lumen ofvagina. Vaginal bacteriametabolizethe glycogenformlactic acid, which causesvaginal pHis low.The pH conditions prevent from pathogenic microorganisms and fungi. Increased estrogenal so cause cell proliferation through the thickening of the epithelium lining of the vagina so that the cells differentiate.Increasing of glycogenin the superficial cells, and  ceratin cells found in the cytoplasm of

  3. Axial offset anomalies and local pH

    International Nuclear Information System (INIS)

    Tarin, F.; Montes, M.; Izquierdo, J.; Garcia-Sanchez, J.

    2001-01-01

    Small radial and axial offset anomalies (AOA) in some Spanish PWR-type NPP's, in addition to the knowledge of the existence of similar anomalies in U.S. PWR's, led us in 1993 to study this problem. Important parameters were correlated for a database of plant operating data consisting of six cycles of five different PWR plants (all of them of the Westinghouse 3-loop, 12 ft., 17 x 17 fuel design). One of these cycles (the oldest one) followed the standard constant pH 308 = 7.0, and the remaining ones followed a modified elevated pH control strategy (the pH at EOC is typically 7.4). Only for the oldest cycle that used the standard pH control was the in-core and ex-core axial offset values found to be in good agreement with the predictions, and an anomalous soluble boron curve behavior not observed. (author)

  4. Low-cycle fatigue behaviors of pre-hardening Hadfield steel

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chen [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Lv, Bo [College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004 (China); Wang, Fei [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Zhang, Fucheng, E-mail: zfc@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); National Engineering Research Center for Equipment and Technology of Cold Strip Rolling, Yanshan University, Qinhuangdao 066004 (China)

    2017-05-17

    Low-cycle fatigue behaviors of the pre-hardening (PH) and the water-quenching (WQ) Hadfield steel were studied using optical microscopy, transmission electron microscopy, and electron backscatter diffraction technique. The effect of the PH treatment on low-cycle fatigue behavior of the Hadfield steel was analyzed through comparing the cyclic hardening/softening behaviors and the changing regulations of stress amplitude, internal stress, and effective stress at different total strain amplitudes. Results showed obvious differences in fatigue behaviors between the PH (with a cold rolling deformation degree of 40%) and the WQ Hadfield steels. Transient hardening followed by cyclic stability behavior occurred in the PH Hadfield steel under cyclic loading, whereas cyclic softening behavior was barely observed. The fatigue life of the PH Hadfield steel was higher than that of the WQ Hadfield steel at relatively low strain amplitudes, while a contrary result was obtained at relatively high strain amplitudes. At low strain amplitudes, the deformation twins induced in the PH Hadfield steel could enhance the multiplication and slip process of dislocations, which actually improved the deformation uniformity. The long-range motion of dislocations was intensified at high strain amplitudes. However, the dislocation motion was also blocked by twin boundaries. As a result, the interactions between dislocations and deformation twins enhanced, finally causing severe dislocation accumulation. These two effects of deformation twins on dislocation motion eventually resulted in different low-cycle fatigue behaviors of the PH Hadfield steel.

  5. PWR primary system chemistry: Experience with elevated pH at Millstone Point Unit 3

    International Nuclear Information System (INIS)

    Bergmann, C.A.; McAtee, K.R.; Roesmer, J.

    1990-08-01

    The maintenance of an elevated pH of the hot reactor coolant in several plants for a fraction of their respective fuel cycles confirmed earlier laboratory findings that an elevated pH (>6.9 at temperature) resulted in reduced component radiation fields. In view of the potential radiological benefits of elevated coolant pH operation, Northeast Utilities (NU) in support of an EPRI- Westinghouse program, agreed to operate the Millstone 3 plants as a demonstration of elevated coolant pH during operation with extended fuel cycles. This report represents the data and describes the effects of operation of the Millstone 3 cycle 2 core at an elevated hot coolant pH of 7.0--7.5 on Zircaloy cladding corrosion, and on the buildup of core crud and excore radiation fields. The following preliminary conclusion were made based on an evaluation of the data obtained after one cycle of Millstone 3 elevated coolant pH operation. Although some of the measured zirconium dioxide thicknesses are greater than expected, the data does not indicate a significant lithium effect on the corrosion rate of the fuel cladding because of the relatively high variability of thickness measurements on rods of similar duty. There was no observable effect of the higher pH operation on any of the other fuel assembly components. Changes in core crude deposit thickness, chemical and radiochemical composition and apparent residence time were noted. These changes are consistent with the expected effects of a more dissolving coolant on activity and crud transport in a primary circuit. The overall radiation exposure rate trends from cycle 1 to cycle 2 indicated a favorable effect of the higher pH operation. 17 figs., 11 tabs

  6. Streptococcus oligofermentans Inhibits Streptococcus mutans in Biofilms at Both Neutral pH and Cariogenic Conditions.

    Science.gov (United States)

    Bao, Xudong; de Soet, Johannes Jacob; Tong, Huichun; Gao, Xuejun; He, Libang; van Loveren, Cor; Deng, Dong Mei

    2015-01-01

    Homeostasis of oral microbiota can be maintained through microbial interactions. Previous studies showed that Streptococcus oligofermentans, a non-mutans streptococci frequently isolated from caries-free subjects, inhibited the cariogenic Streptococcus mutans by the production of hydrogen peroxide (HP). Since pH is a critical factor in caries formation, we aimed to study the influence of pH on the competition between S. oligofermentans and S. mutans in biofilms. To this end, S. mutans and S. oligofermentans were inoculated alone or mixed at 1:1 ratio in buffered biofilm medium in a 96-well active attachment model. The single- and dual-species biofilms were grown under either constantly neutral pH or pH-cycling conditions. The latter includes two cycles of 8 h neutral pH and 16 h pH 5.5, used to mimic cariogenic condition. The 48 h biofilms were analysed for the viable cell counts, lactate and HP production. The last two measurements were carried out after incubating the 48 h biofilms in buffers supplemented with 1% glucose (pH 7.0) for 4 h. The results showed that S. oligofermentans inhibited the growth of S. mutans in dual-species biofilms under both tested pH conditions. The lactic acid production of dual-species biofilms was significantly lower than that of single-species S. mutans biofilms. Moreover, dual-species and single-species S. oligofermentans biofilms grown under pH-cycling conditions (with a 16 h low pH period) produced a significantly higher amount of HP than those grown under constantly neutral pH. In conclusion, S. oligofermentans inhibited S. mutans in biofilms not only under neutral pH, but also under pH-cycling conditions, likely through HP production. S. oligofermentans may be a compelling probiotic candidate against caries.

  7. Redox Cycling, pH Dependence, and Ligand Effects of Mn(III) in Oxalate Decarboxylase from Bacillus subtilis.

    Science.gov (United States)

    Twahir, Umar T; Ozarowski, Andrew; Angerhofer, Alexander

    2016-11-29

    This contribution describes electron paramagnetic resonance (EPR) experiments on Mn(III) in oxalate decarboxylase of Bacillus subtilis, an interesting enzyme that catalyzes the redox-neutral dissociation of oxalate into formate and carbon dioxide. Chemical redox cycling provides strong evidence that both Mn centers can be oxidized, although the N-terminal Mn(II) appears to have the lower reduction potential and is most likely the carrier of the +3 oxidation state under moderate oxidative conditions, in agreement with the general view that it represents the active site. Significantly, Mn(III) was observed in untreated OxDC in succinate and acetate buffers, while it could not be directly observed in citrate buffer. Quantitative analysis showed that up to 16% of the EPR-visible Mn is in the +3 oxidation state at low pH in the presence of succinate buffer. The fine structure and hyperfine structure parameters of Mn(III) are affected by small carboxylate ligands that can enter the active site and have been recorded for formate, acetate, and succinate. The results from a previous report [Zhu, W., et al. (2016) Biochemistry 55, 429-434] could therefore be reinterpreted as evidence of formate-bound Mn(III) after the enzyme is allowed to turn over oxalate. The pH dependence of the Mn(III) EPR signal compares very well with that of enzymatic activity, providing strong evidence that the catalytic reaction of oxalate decarboxylase is driven by Mn(III), which is generated in the presence of dioxygen.

  8. Influence of storage solution on enamel demineralization submitted to pH cycling Influência da solução de armazenagem na desmineralização do esmalte submetido à ciclagem de pH

    Directory of Open Access Journals (Sweden)

    Juliana Silva Moura

    2004-09-01

    Full Text Available Extracted human teeth are frequently used for research or educational purposes. Therefore, it is necessary to store them in disinfectant solutions that do not alter dental structures. Thus, this study evaluated the influence of storage solution on enamel demineralization. For that purpose, sixty samples were divided into the following groups: enamel stored in formaldehyde (F1, stored in thymol (T1, stored in formaldehyde and submitted to pH cycling (F2, stored in thymol and submitted to pH cycling (T2. All samples were evaluated by cross-sectional microhardness analysis and had their percentage of mineral volume versus micrometer (integrated area determined. Differences between groups were found up to 30-µm depth from the enamel surface (p Dentes humanos extraídos são freqüentemente utilizados para propósitos educacionais ou de pesquisa. Desta forma, é necessário o armazenamento dos mesmos em soluções desinfetantes que não alterem a estrutura dental. Para tanto, sessenta espécimes foram divididos nos seguintes grupos: esmalte armazenado em formol (F1, armazenado em timol (T1, armazenado em formol e submetido à ciclagem de pH (F2 e armazenado em timol e submetido à ciclagem de pH (T2, sendo avaliados por meio de análise de microdureza longitudinal e tiveram a porcentagem de volume mineral pro micrômetro determinada. Diferenças entre os grupos foram encontradas até a profundidade de 30µm da superfície do esmalte (p<0,05, onde o grupo mais desmineralizado era T2. Foi concluído que a solução de armazenagem influenciou na reação do substrato dental a um desafio cariogênico, sugerindo que o formaldeído pode aumentar a resistência do esmalte à desmineralização promovida pelo modelo de ciclagem de pH, quando comparado à desmineralização ocorrida no esmalte armazenado em timol.

  9. Secondary side water chemistry pH control strategy improvements

    International Nuclear Information System (INIS)

    Roumiguiere, Fernando-Mario; Fandrich, Joerg; Ramminger, Ute; Hoffmann-Wankerl, Stephan; Drexler, Andreas

    2012-09-01

    Over the years the PWR plant operators were aware of the need of optimizing the pH control strategy in the water-steam cycle with the focus on improvement of steam generator performance with the main goal of reducing the corrosion product ingress into the steam generators and their consequences: SG fouling, SG tube corrosion beneath deposits. To achieve this goal, it becomes necessary to harmonize three requirements: a. High overall pH along the circuit for suppression of general corrosion, requiring a volatile amine to ensure a suitable distribution in steam areas and condenser, and b. High local pH at the water phase of two-phase flow areas, requiring an either rather low volatile amine to ensure high pH in the wet steam water film, or larger amounts of a volatile amine. c. Sufficient amount of hydrazine to ensure reducing conditions in the steam generators. The basic strategy of AREVA NP GmbH (formerly KWU), successfully applied in German nuclear power plants since the late seventies consisted on the achievement of the necessary pH by means of ammonia, as generated by thermal decomposition of hydrazine. By dosing of hydrazine at the necessary amounts to ensure reducing conditions, also sufficient ammonia is generated to achieve a high overall pH along the cycle, being the target pH (25 deg. C) ≥ 9.8 resulting in < 1 ppb Fe in final feed water. This treatment is known as H-AVT (High pH - All Volatile Treatment). Main prerequisite for its application is to have a copper-free system. Eventually, H-AVT started to be applied later at some other western nuclear power plants. In some units, the high condenser exhaust flow rate applied caused a considerable amount of ammonia being removed from the cycle, resulting in too low ammonia concentrations to maintain a sufficiently high pH, making the addition of ammonia necessary. AREVA NP GmbH together with plant operators investigated the possibility of complementing the applied classical H-AVT by addition of an advanced

  10. The relationship between mantle pH and the deep nitrogen cycle

    Science.gov (United States)

    Mikhail, Sami; Barry, Peter H.; Sverjensky, Dimitri A.

    2017-07-01

    Nitrogen is distributed throughout all terrestrial geological reservoirs (i.e., the crust, mantle, and core), which are in a constant state of disequilibrium due to metabolic factors at Earth's surface, chemical weathering, diffusion, and deep N fluxes imposed by plate tectonics. However, the behavior of nitrogen during subduction is the subject of ongoing debate. There is a general consensus that during the crystallization of minerals from melts, monatomic nitrogen behaves like argon (highly incompatible) and ammonium behaves like potassium and rubidium (which are relatively less incompatible). Therefore, the behavior of nitrogen is fundamentally underpinned by its chemical speciation. In aqueous fluids, the controlling factor which determines if nitrogen is molecular (N2) or ammonic (inclusive of both NH4+ and NH30) is oxygen fugacity, whereas pH designates if ammonic nitrogen is NH4+ or NH30. Therefore, to address the speciation of nitrogen at high pressures and temperatures, one must also consider pH at the respective pressure-temperature conditions. To accomplish this goal we have used the Deep Earth Water Model (DEW) to calculate the activities of aqueous nitrogen from 1-5 GPa and 600-1000 °C in equilibrium with a model eclogite-facies mineral assemblage of jadeite + kyanite + quartz/coesite (metasediment), jadeite + pyrope + talc + quartz/coesite (metamorphosed mafic rocks), and carbonaceous eclogite (metamorphosed mafic rocks + elemental carbon). We then compare these data with previously published data for the speciation of aqueous nitrogen across these respective P-T conditions in equilibrium with a model peridotite mineral assemblage (Mikhail and Sverjensky, 2014). In addition, we have carried out full aqueous speciation and solubility calculations for the more complex fluids in equilibrium with jadeite + pyrope + kyanite + diamond, and for fluids in equilibrium with forsterite + enstatite + pyrope + diamond. Our results show that the pH of the fluid is

  11. Diel cycling of zinc in a stream impacted by acid rock drainage: Initial results from a new in situ Zn analyzer

    Science.gov (United States)

    Chapin, T.P.; Nimick, D.A.; Gammons, C.H.; Wanty, R.B.

    2007-01-01

    Recent work has demonstrated that many trace metals undergo dramatic diel (24-h) cycles in near neutral pH streams with metal concentrations reproducibly changing up to 500% during the diel period (Nimick et al., 2003). To examine diel zinc cycles in streams affected by acid rock drainage, we have developed a novel instrument, the Zn-DigiScan, to continuously monitor in situ zinc concentrations in near real-time. Initial results from a 3-day deployment at Fisher Creek, Montana have demonstrated the ability of the Zn-DigiScan to record diel Zn cycling at levels below 100 ??g/l. Longer deployments of this instrument could be used to examine the effects of episodic events such as rainstorms and snowmelt pulses on zinc loading in streams affected by acid rock drainage. ?? Springer Science+Business Media B.V. 2006.

  12. Variation in pH optima of hydrolytic enzyme activities in tropical rain forest soils.

    Science.gov (United States)

    Turner, Benjamin L

    2010-10-01

    Extracellular enzymes synthesized by soil microbes play a central role in the biogeochemical cycling of nutrients in the environment. The pH optima of eight hydrolytic enzymes involved in the cycles of carbon, nitrogen, phosphorus, and sulfur, were assessed in a series of tropical forest soils of contrasting pH values from the Republic of Panama. Assays were conducted using 4-methylumbelliferone-linked fluorogenic substrates in modified universal buffer. Optimum pH values differed markedly among enzymes and soils. Enzymes were grouped into three classes based on their pH optima: (i) enzymes with acidic pH optima that were consistent among soils (cellobiohydrolase, β-xylanase, and arylsulfatase), (ii) enzymes with acidic pH optima that varied systematically with soil pH, with the most acidic pH optima in the most acidic soils (α-glucosidase, β-glucosidase, and N-acetyl-β-glucosaminidase), and (iii) enzymes with an optimum pH in either the acid range or the alkaline range depending on soil pH (phosphomonoesterase and phosphodiesterase). The optimum pH values of phosphomonoesterase were consistent among soils, being 4 to 5 for acid phosphomonoesterase and 10 to 11 for alkaline phosphomonoesterase. In contrast, the optimum pH for phosphodiesterase activity varied systematically with soil pH, with the most acidic pH optima (3.0) in the most acidic soils and the most alkaline pH optima (pH 10) in near-neutral soils. Arylsulfatase activity had a very acidic optimum pH in all soils (pH ≤3.0) irrespective of soil pH. The differences in pH optima may be linked to the origins of the enzymes and/or the degree of stabilization on solid surfaces. The results have important implications for the interpretation of hydrolytic enzyme assays using fluorogenic substrates.

  13. Carbon steel corrosion under anaerobic-aerobic cycling conditions in near-neutral pH saline solutions - Part 1: Long term corrosion behaviour

    International Nuclear Information System (INIS)

    Sherar, B.W.A.; Keech, P.G.; Shoesmith, D.W.

    2011-01-01

    Highlights: → Anaerobic-aerobic cycling on pipeline steel forms two distinct surface morphologies. → Seventy-five percentage of the surface was covered by a black, compact layer ∼4.5 μm thick. → A tubercle, ∼3 to 4 mm in cross section, covered the remaining 25% of surface. → The tubercle cross section showed a single large pit ∼275 μm deep. - Abstract: The influence of anaerobic-aerobic cycling on pipeline steel corrosion was investigated in near-neutral carbonate/sulphate/chloride solution (pH 9) over 238 days. The corrosion rate increased and decreased as exposure conditions were switched between redox conditions. Two distinct corrosion morphologies were observed. The majority of the surface corroded uniformly to produce a black magnetite/maghemite layer approximately 4.5 μm thick. The remaining surface was covered with an orange tubercle, approximately 3-4 mm in cross section. Analysis of the tubercle cross section revealed a single large pit approximately 275 μm deep. Repeated anaerobic-aerobic cycling localized the corrosion process within this tubercle-covered pit.

  14. Foliar pH as a new plant trait: can it explain variation in foliar chemistry and carbon cycling processes among subarctic plant species and types?

    Science.gov (United States)

    Cornelissen, J H C; Quested, H M; van Logtestijn, R S P; Pérez-Harguindeguy, N; Gwynn-Jones, D; Díaz, S; Callaghan, T V; Press, M C; Aerts, R

    2006-03-01

    Plant traits have become popular as predictors of interspecific variation in important ecosystem properties and processes. Here we introduce foliar pH as a possible new plant trait, and tested whether (1) green leaf pH or leaf litter pH correlates with biochemical and structural foliar traits that are linked to biogeochemical cycling; (2) there is consistent variation in green leaf pH or leaf litter pH among plant types as defined by nutrient uptake mode and higher taxonomy; (3) green leaf pH can predict a significant proportion of variation in leaf digestibility among plant species and types; (4) leaf litter pH can predict a significant proportion of variation in leaf litter decomposability among plant species and types. We found some evidence in support of all four hypotheses for a wide range of species in a subarctic flora, although cryptogams (fern allies and a moss) tended to weaken the patterns by showing relatively poor leaf digestibility or litter decomposability at a given pH. Among seed plant species, green leaf pH itself explained only up to a third of the interspecific variation in leaf digestibility and leaf litter up to a quarter of the interspecific variation in leaf litter decomposability. However, foliar pH substantially improved the power of foliar lignin and/or cellulose concentrations as predictors of these processes when added to regression models as a second variable. When species were aggregated into plant types as defined by higher taxonomy and nutrient uptake mode, green-specific leaf area was a more powerful predictor of digestibility or decomposability than any of the biochemical traits including pH. The usefulness of foliar pH as a new predictive trait, whether or not in combination with other traits, remains to be tested across more plant species, types and biomes, and also in relation to other plant or ecosystem traits and processes.

  15. Request for All - Generalized Request Framework for PhEDEx

    CERN Document Server

    Huang, C-H; Ratnikova, N.; Sanchez-Hernandez, A.; Zhang, X.; Magini, N.

    2014-01-01

    PhEDEx has been serving CMS community since 2004 as the data broker. Every PhEDEx operation is initiated by a request, such as request to move data, request to delete data, and so on. A request has it own life cycle, including creation, approval, notification, and book keeping and the details depend on its type. Currently, only two kinds of requests, transfer and deletion, are fully integrated in PhEDEx. They are tailored specifically to the operations workflows. To be able to serve a new type of request it generally means a fair amount of development work.After several years of operation, we have gathered enough experience to rethink the request handling in PhEDEx. Generalized Request Project is set to abstract such experience and come up with a request system which is not tied into current workflow yet it is general enough to accommodate current and future requests.The challenges are dealing with different stages in a requests life cycle, complexity of approval process and complexity of the ability and auth...

  16. Ph3CCOOSnPh3.Ph3PO AND Ph3CCOOSnPh3.Ph3AsO: SYNTHESIS AND INFRARED STUDY

    Directory of Open Access Journals (Sweden)

    ABDOU MBAYE

    2014-08-01

    Full Text Available The mixture of ethanolic solutions of Ph3CCOOSnPh3 and Ph3PO or Ph3AsO gives Ph3CCOOSnPh3.Ph3PO and Ph3CCOOSnPh3.Ph3AsO adducts which have been characterized by infrared spectroscopy. A discrete structure is suggested for both, the environment around the tin centre being trigonal bipyramidal, the triphenylacetate anion behaving as a mondentate ligand.

  17. Variation in pH Optima of Hydrolytic Enzyme Activities in Tropical Rain Forest Soils ▿

    OpenAIRE

    Turner, Benjamin L.

    2010-01-01

    Extracellular enzymes synthesized by soil microbes play a central role in the biogeochemical cycling of nutrients in the environment. The pH optima of eight hydrolytic enzymes involved in the cycles of carbon, nitrogen, phosphorus, and sulfur, were assessed in a series of tropical forest soils of contrasting pH values from the Republic of Panama. Assays were conducted using 4-methylumbelliferone-linked fluorogenic substrates in modified universal buffer. Optimum pH values differed markedly am...

  18. Future changes in the Baltic Sea acid–base (pH and oxygen balances

    Directory of Open Access Journals (Sweden)

    Anders Omstedt

    2012-12-01

    Full Text Available Possible future changes in Baltic Sea acid–base (pH and oxygen balances were studied using a catchment–sea coupled model system and numerical experiments based on meteorological and hydrological forcing datasets and scenarios. By using objective statistical methods, climate runs for present climate conditions were examined and evaluated using Baltic Sea modelling. The results indicate that increased nutrient loads will not inhibit future Baltic Sea acidification; instead, the seasonal pH cycle will be amplified by increased biological production and mineralization. All examined scenarios indicate future acidification of the whole Baltic Sea that is insensitive to the chosen global climate model. The main factor controlling the direction and magnitude of future pH changes is atmospheric CO2 concentration (i.e. emissions. Climate change and land-derived changes (e.g. nutrient loads affect acidification mainly by altering the seasonal cycle and deep-water conditions. Apart from decreasing pH, we also project a decreased saturation state of calcium carbonate, decreased respiration index and increasing hypoxic area – all factors that will threaten the marine ecosystem. We demonstrate that substantial reductions in fossil-fuel burning are needed to minimise the coming pH decrease and that substantial reductions in nutrient loads are needed to reduce the coming increase in hypoxic and anoxic waters.

  19. Iridium Oxide pH Sensor Based on Stainless Steel Wire for pH Mapping on Metal Surface

    Science.gov (United States)

    Shahrestani, S.; Ismail, M. C.; Kakooei, S.; Beheshti, M.; Zabihiazadboni, M.; Zavareh, M. A.

    2018-03-01

    A simple technique to fabricate the iridium oxide pH sensor is useful in several applications such as medical, food processing and engineering material where it is able to detect the changes of pH. Generally, the fabrication technique can be classified into three types: electro-deposition iridium oxide film (EIrOF), activated iridium oxide film (AIROF) and sputtering iridium oxide film (SIROF). This study focuses on fabricating electrode, calibration and test. Electro-deposition iridium oxide film is a simple and effective method of fabricating this kind of sensor via cyclic voltammetry process. The iridium oxide thick film was successfully electrodeposited on the surface of stainless steel wire with 500 cycles of sweep potential. A further analysis under FESEM shows detailed image of iridium oxide film which has cauliflower-liked microstructure. EDX analysis shows the highest element present are iridium and oxygen which concluded that the process is successful. The iridium oxide based pH sensor has shown a good performance in comparison to conventional glass pH sensor when it is being calibrated in buffer solutions with 2, 4, 7 and 9 pH values. The iridium oxide pH sensor is specifically designed to measure the pH on the surface of metal plate.

  20. Increase of carbon cycle feedback with climate sensitivity: results from a coupled climate and carbon cycle model

    International Nuclear Information System (INIS)

    Govindasamy, B.; Thompson, S.; Mirin, A.; Wickett, M.; Caldeira, K.; Delire, C.

    2005-01-01

    Coupled climate and carbon cycle modelling studies have shown that the feedback between global warming and the carbon cycle, in particular the terrestrial carbon cycle, could accelerate climate change and result in greater warming. In this paper we investigate the sensitivity of this feedback for year 2100 global warming in the range of 0 to 8 K. Differing climate sensitivities to increased CO 2 content are imposed on the carbon cycle models for the same emissions. Emissions from the SRES A2 scenario are used. We use a fully coupled climate and carbon cycle model, the INtegrated Climate and CArbon model (INCCA), the NCAR/DOE Parallel Climate Model coupled to the IBIS terrestrial biosphere model and a modified OCMIP ocean biogeochemistry model. In our integrated model, for scenarios with year 2100 global warming increasing from 0 to 8 K, land uptake decreases from 47% to 29% of total CO 2 emissions. Due to competing effects, ocean uptake (16%) shows almost no change at all. Atmospheric CO 2 concentration increases are 48% higher in the run with 8 K global climate warming than in the case with no warming. Our results indicate that carbon cycle amplification of climate warming will be greater if there is higher climate sensitivity to increased atmospheric CO 2 content; the carbon cycle feedback factor increases from 1.13 to 1.48 when global warming increases from 3.2 to 8 K

  1. Ramsey Results for Cycle Spectra

    DEFF Research Database (Denmark)

    Brandt, S.; Joos, F.; Muttel, J.

    2013-01-01

    Let C(G) denote the set of lengths of cycles of a graph G of order n and let (G) over bar denote the complement of G. We show that if n >= 6, then C(G) boolean OR C((G) over bar) contains all odd l with 3......Let C(G) denote the set of lengths of cycles of a graph G of order n and let (G) over bar denote the complement of G. We show that if n >= 6, then C(G) boolean OR C((G) over bar) contains all odd l with 3...

  2. pH Regulatory Transporters in Pancreatic Ductal Adenocarcinoma

    DEFF Research Database (Denmark)

    Kong, Su Chii

    The abnormal features of hypoxia and altered metabolisms in solid tumours lead to an increased glycolysis that is uncoupled from oxidative phosphorylation in the TCA cycle. Tumoural cells often exhibit dysregulated expressions and activities of various membrane pH regulatory transporters to cope...... with the elevated acid production from this glycolysis, as well as from cellular ATP hydrolysis, sequentially creating a favourable intracellular pH and hostile acidic tumour microenvironment, fortify the tumour cells with highly invasive, metastatic and drug resistant phenotype. In current work, we study...... proliferation was found to be decreased while apoptosis was increased with concanamycin A treatment, indicative of V-ATPases being involved in PDAC cell survival mechanisms as well. Comprehending pH regulation in tumour cells might provide insights in preventing tumourigenesis by pH disruptions. Data presented...

  3. Synthesis of low cycle fatigue test results

    International Nuclear Information System (INIS)

    Andrews, R.M.

    1990-01-01

    Axial strain controlled cycle fatigue tests were carried out on type 316 stainless steel parent metal, vacuum and non-vacuum electron beams welds, submerged arc welds and gas shielded metal arc welds. Testing covered total strains in the range 0.6% to 2%, and was at room temperature and 550 0 C. Parent metal and the electron beam welds showed rapid cyclic hardening, while arc welds showed little hardening. The weld metal cyclic stress-strain response was above that obtained for the parent metal, although below data obtained by other workers for similar parent materials. Weld metal endurances were above the ASME N47 continuous cycling design line at both temperatures, and comparable with parent metal data. However, the weld metal data approached the design line at low strain ranges (around 0.5%). Endurances were predicted from crack growth rates estimated from striation spacings, giving acceptable results except for the gas shielded metal arc weldments. (author)

  4. Radiation-induced apoptosis in different pH environments in vitro

    International Nuclear Information System (INIS)

    Lee, Hyung-Sik; Park, Heon J.; Lyons, John C.; Griffin, Robert J.; Auger, Elizabeth A.; Song, Chang W.

    1997-01-01

    Purpose: The effect of environmental pH on the radiation-induced apoptosis in tumor cells in vitro was investigated. Methods and Materials: Mammary adenocarcinoma cells of A/J mice (SCK cells) were irradiated with γ-rays using a 137 Cs irradiator and incubated in media of different pHs. After incubation at 37 deg. C for 24-120 h the extent of apoptosis was determined using agarose gel electrophoresis, TdT-mediated dUTP-biotin nick end labeling (TUNEL) staining, flow cytometry, and release of 3 H from 3 H-thymidine labeled cells. The clonogenicity of the cells irradiated in different pH medium was determined, and the progression of cells through the cell cycle after irradiation in different pHs was also determined with flow cytometry. Results: Irradiation with 2-12 Gy of γ-rays induced apoptosis in SCK cells in pH 7.5 medium within 48 h as judged from the results of four different assays mentioned. Radiation-induced apoptosis declined as the medium pH was lowered from 7.5 to 6.4. Specifically, the radiation-induced degradation of DNA including the early DNA breaks, as determined with the TUNEL method, progressively declined as the medium pH was lowered so that little DNA fragmentation occurred 48 h after irradiation with 12 Gy in pH 6.6 medium. When the cells were irradiated and incubated for 48 h in pH 6.6 medium and the medium was replaced with pH 7.5 medium, DNA fragmentation promptly occurred. DNA fragmentation also occurred even in pH 6.6 medium when the cells were irradiated and maintained in pH 7.5 medium for 8 h or longer post-irradiation before incubation in pH 6.6 medium. The radiation-induced G 2 arrest in pH 6.6 medium lasted markedly longer than that in pH 7.5 medium. Conclusion: Radiation-induced apoptosis in SCK cells in vitro is reversibly suppressed in an acidic environment. Taking the results of four different assays together, it was concluded that early step(s) in the apoptotic pathway, probably the DNA break or upstream of DNA break, is

  5. Effect of drying-wetting cycles on leaching behavior of cement solidified lead-contaminated soil.

    Science.gov (United States)

    Li, Jiang-Shan; Xue, Qiang; Wang, Ping; Li, Zhen-Ze; Liu, Lei

    2014-12-01

    Lead contaminated soil was treated by different concentration of ordinary Portland cement (OPC). Solidified cylindrical samples were dried at 40°C in oven for 48 h subsequent to 24h of immersing in different solution for one drying-wetting. 10 cycles were conducted on specimens. The changes in mass loss of specimens, as well as leaching concentration and pH of filtered leachates were studied after each cycle. Results indicated that drying-wetting cycles could accelerate the leaching and deterioration of solidified specimens. The cumulative leached lead with acetic acid (pH=2.88) in this study was 109, 83 and 71 mg respectively for solidified specimens of cement-to-dry soil (C/Sd) ratios 0.2, 0.3 and 0.4, compared to 37, 30, and 25mg for a semi-dynamic leaching test. With the increase of cycle times, the cumulative mass loss of specimens increased linearly, but pH of filtered leachates decreased. The leachability and deterioration of solidified specimens increased with acidity of solution. Increases of C/Sd clearly reduced the leachability and deterioration behavior. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Strong shift from HCO3 (-) to CO 2 uptake in Emiliania huxleyi with acidification: new approach unravels acclimation versus short-term pH effects.

    Science.gov (United States)

    Kottmeier, Dorothee M; Rokitta, Sebastian D; Tortell, Philippe D; Rost, Björn

    2014-09-01

    Effects of ocean acidification on Emiliania huxleyi strain RCC 1216 (calcifying, diploid life-cycle stage) and RCC 1217 (non-calcifying, haploid life-cycle stage) were investigated by measuring growth, elemental composition, and production rates under different pCO2 levels (380 and 950 μatm). In these differently acclimated cells, the photosynthetic carbon source was assessed by a (14)C disequilibrium assay, conducted over a range of ecologically relevant pH values (7.9-8.7). In agreement with previous studies, we observed decreased calcification and stimulated biomass production in diploid cells under high pCO2, but no CO2-dependent changes in biomass production for haploid cells. In both life-cycle stages, the relative contributions of CO2 and HCO3 (-) uptake depended strongly on the assay pH. At pH values ≤ 8.1, cells preferentially used CO2 (≥ 90 % CO2), whereas at pH values ≥ 8.3, cells progressively increased the fraction of HCO3 (-) uptake (~45 % CO2 at pH 8.7 in diploid cells; ~55 % CO2 at pH 8.5 in haploid cells). In contrast to the short-term effect of the assay pH, the pCO2 acclimation history had no significant effect on the carbon uptake behavior. A numerical sensitivity study confirmed that the pH-modification in the (14)C disequilibrium method yields reliable results, provided that model parameters (e.g., pH, temperature) are kept within typical measurement uncertainties. Our results demonstrate a high plasticity of E. huxleyi to rapidly adjust carbon acquisition to the external carbon supply and/or pH, and provide an explanation for the paradoxical observation of high CO2 sensitivity despite the apparently high HCO3 (-) usage seen in previous studies.

  7. Low pH induces co-ordinate regulation of gene expression in oesophageal cells.

    Science.gov (United States)

    Duggan, Shane P; Gallagher, William M; Fox, Edward J P; Abdel-Latif, Mohammed M; Reynolds, John V; Kelleher, Dermot

    2006-02-01

    The development of gastro-oesophageal reflux disease (GORD) is known to be a causative risk factor in the evolution of adenocarcinoma of the oesophagus. The major component of this reflux is gastric acid. However, the impact of low pH on gene expression has not been extensively studied in oesophageal cells. This study utilizes a transcriptomic and bioinformatic approach to assess regulation of gene expression in response to low pH. In more detail, oesophageal adenocarcinoma cell lines were exposed to a range of pH environments. Affymetrix microarrays were used for gene-expression analysis and results were validated using cycle limitation and real-time RT-PCR analysis, as well as northern and western blotting. Comparative promoter transcription factor binding site (TFBS) analysis (MatInspector) of hierarchically clustered gene-expression data was employed to identify the elements which may co-ordinately regulate individual gene clusters. Initial experiments demonstrated maximal induction of EGR1 gene expression at pH 6.5. Subsequent array experimentation revealed significant induction of gene expression from such functional categories as DNA damage response (EGR1-4, ATF3) and cell-cycle control (GADD34, GADD45, p57). Changes in expression of EGR1, EGR3, ATF3, MKP-1, FOSB, CTGF and CYR61 were verified in separate experiments and in a variety of oesophageal cell lines. TFBS analysis of promoters identified transcription factors that may co-ordinately regulate gene-expression clusters, Cluster 1: Oct-1, AP4R; Cluster 2: NF-kB, EGRF; Cluster 3: IKRS, AP-1F. Low pH has the ability to induce genes and pathways which can provide an environment suitable for the progression of malignancy. Further functional analysis of the genes and clusters identified in this low pH study is likely to lead to new insights into the pathogenesis and therapeutics of GORD and oesophageal cancer.

  8. Effect of cytosolic pH on inward currents reveals structural characteristics of the proton transport cycle in the influenza A protein M2 in cell-free membrane patches of Xenopus oocytes.

    Directory of Open Access Journals (Sweden)

    Mattia L DiFrancesco

    Full Text Available Transport activity through the mutant D44A of the M2 proton channel from influenza virus A was measured in excised inside-out macro-patches of Xenopus laevis oocytes at cytosolic pH values of 5.5, 7.5 and 8.2. The current-voltage relationships reveal some peculiarities: 1. "Transinhibition", i.e., instead of an increase of unidirectional outward current with increasing cytosolic H(+ concentration, a decrease of unidirectional inward current was found. 2. Strong inward rectification. 3. Exponential rise of current with negative potentials. In order to interpret these findings in molecular terms, different kinetic models have been tested. The transinhibition basically results from a strong binding of H(+ to a site in the pore, presumably His37. This assumption alone already provides inward rectification and exponential rise of the IV curves. However, it results in poor global fits of the IV curves, i.e., good fits were only obtained for cytosolic pH of 8.2, but not for 7.5. Assuming an additional transport step as e.g. caused by a constriction zone at Val27 resulted in a negligible improvement. In contrast, good global fits for cytosolic pH of 7.5 and 8.2 were immediately obtained with a cyclic model. A "recycling step" implies that the protein undergoes conformational changes (assigned to Trp41 and Val27 during transport which have to be reset before the next proton can be transported. The global fit failed at the low currents at pHcyt = 5.5, as expected from the interference of putative transport of other ions besides H(+. Alternatively, a regulatory effect of acidic cytosolic pH may be assumed which strongly modifies the rate constants of the transport cycle.

  9. ISFET sensor evaluation and modification for seawater pH measurement

    Science.gov (United States)

    Martz, T. R.; Johnson, K. S.; Jannasch, H.; Coletti, L.; Barry, J.; Lovera, C.

    2008-12-01

    In the future, short-term cycles (daily to subannual) and long-term trends (annual and greater) in the carbonate system will be observed by autonomous sensors operating from a variety of platforms (e.g., moorings, profiling floats, AUVs, etc.). Of the four carbonate parameters, pH measurement has the longest history of development - yet robust autonomous sensing techniques remain elusive due to a catalog of technical challenges. Existing commercial sensor technologies generally do not meet the stringent demands of accuracy, long-term stability, low power, pressure tolerance, resistance to biofouling, and ease of use required by the oceanographic community. We report here on some recent advances in Ion Sensitive Field Effect Transistor (ISFET) technology that may open the door for more widespread autonomous seawater pH measurements. Much of our work has focused on applications of the Honeywell Durafet pH sensor, a product designed for industrial process control. Initial results from laboratory testing and deployments in the MBARI test tank and near shore moorings will be presented. Sensor calibration techniques will be addressed. Applications of now-available off-the-shelf sensors including shipboard underway measurement, shallow water mooring deployment, and a gas controlled seawater aquarium for pH perturbation experiments will be discussed. We hope that an ongoing collaboration between MBARI and Honeywell will result in a commercially available product, designed specifically for oceanographic applications, within the next several years.

  10. Aeroelastic Limit-Cycle Oscillations resulting from Aerodynamic Non-Linearities

    NARCIS (Netherlands)

    van Rooij, A.C.L.M.

    2017-01-01

    Aerodynamic non-linearities, such as shock waves, boundary layer separation or boundary layer transition, may cause an amplitude limitation of the oscillations induced by the fluid flow around a structure. These aeroelastic limit-cycle oscillations (LCOs) resulting from aerodynamic non-linearities

  11. Plant-Sediment Interactions in Salt Marshes - An Optode Imaging Study of O2, pH, and CO 2 Gradients in the Rhizosphere.

    Science.gov (United States)

    Koop-Jakobsen, Ketil; Mueller, Peter; Meier, Robert J; Liebsch, Gregor; Jensen, Kai

    2018-01-01

    In many wetland plants, belowground transport of O 2 via aerenchyma tissue and subsequent O 2 loss across root surfaces generates small oxic root zones at depth in the rhizosphere with important consequences for carbon and nutrient cycling. This study demonstrates how roots of the intertidal salt-marsh plant Spartina anglica affect not only O 2 , but also pH and CO 2 dynamics, resulting in distinct gradients of O 2 , pH, and CO 2 in the rhizosphere. A novel planar optode system (VisiSens TD ® , PreSens GmbH) was used for taking high-resolution 2D-images of the O 2 , pH, and CO 2 distribution around roots during alternating light-dark cycles. Belowground sediment oxygenation was detected in the immediate vicinity of the roots, resulting in oxic root zones with a 1.7 mm radius from the root surface. CO 2 accumulated around the roots, reaching a concentration up to threefold higher than the background concentration, and generally affected a larger area within a radius of 12.6 mm from the root surface. This contributed to a lowering of pH by 0.6 units around the roots. The O 2 , pH, and CO 2 distribution was recorded on the same individual roots over diurnal light cycles in order to investigate the interlinkage between sediment oxygenation and CO 2 and pH patterns. In the rhizosphere, oxic root zones showed higher oxygen concentrations during illumination of the aboveground biomass. In darkness, intraspecific differences were observed, where some plants maintained oxic root zones in darkness, while others did not. However, the temporal variation in sediment oxygenation was not reflected in the temporal variations of pH and CO 2 around the roots, which were unaffected by changing light conditions at all times. This demonstrates that plant-mediated sediment oxygenation fueling microbial decomposition and chemical oxidation has limited impact on the dynamics of pH and CO 2 in S. anglica rhizospheres, which may in turn be controlled by other processes such as root

  12. In Vitro Effects of Bromoalkyl Phenytoin Derivatives on Regulated Death, Cell Cycle and Ultrastructure of Leukemia Cells.

    Science.gov (United States)

    Śladowska, Katarzyna; Opydo-Chanek, Małgorzata; Król, Teodora; Trybus, Wojciech; Trybus, Ewa; Kopacz-Bednarska, Anna; Handzlik, Jadwiga; Kieć-Kononowicz, Katarzyna; Mazur, Lidia

    2017-11-01

    To search for new antileukemic agents, the chemical structure of phenytoin was modified. A possible cytotoxic activity of three bromoalkyl phenytoin analogs, methyl 2-(1-(3-bromopropyl)-2,4-dioxo-5,5-diphenylimidazolidin-3-yl) propanoate (PH2), 1-(3-bromopropyl)-3-methyl-5,5-diphenylimidazolidine-2,4-dione (PH3) and 1-(4-bromobutyl)-3-methyl-5,5-diphenylimidazolidine-2,4-dione (PH4) on regulated cell death, the cell cycle and cell ultrastructure was assessed. The experiments were performed in vitro on HL-60 and U937 cells, using flow cytometry and electron microscopy methods. Application of PH2, PH3, and PH4 resulted in cell surface exposure of phosphatidylserine and plasma membrane impairment, caspase-8, -9, and -3/7 activation, dissipation of mitochondrial membrane potential, DNA breakage, cell-cycle disturbance and cell ultrastructural changes. In general, PH3 appeared to be the most active against the leukemia cells, and all bromoalkyl hydantoins, PH2-PH4, were more active in HL-60 cells than in U937 cells. The antileukemic activity of the bromoalkyl phenytoin analogs depended on the combination of N-hydantoin substituents and the human cell line used. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

  13. Empirical algorithms to estimate water column pH in the Southern Ocean

    Science.gov (United States)

    Williams, N. L.; Juranek, L. W.; Johnson, K. S.; Feely, R. A.; Riser, S. C.; Talley, L. D.; Russell, J. L.; Sarmiento, J. L.; Wanninkhof, R.

    2016-04-01

    Empirical algorithms are developed using high-quality GO-SHIP hydrographic measurements of commonly measured parameters (temperature, salinity, pressure, nitrate, and oxygen) that estimate pH in the Pacific sector of the Southern Ocean. The coefficients of determination, R2, are 0.98 for pH from nitrate (pHN) and 0.97 for pH from oxygen (pHOx) with RMS errors of 0.010 and 0.008, respectively. These algorithms are applied to Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) biogeochemical profiling floats, which include novel sensors (pH, nitrate, oxygen, fluorescence, and backscatter). These algorithms are used to estimate pH on floats with no pH sensors and to validate and adjust pH sensor data from floats with pH sensors. The adjusted float data provide, for the first time, seasonal cycles in surface pH on weekly resolution that range from 0.05 to 0.08 on weekly resolution for the Pacific sector of the Southern Ocean.

  14. Injection moulded microneedle sensor for real-time wireless pH monitoring.

    Science.gov (United States)

    Mirza, Khalid B; Zuliani, Claudio; Hou, Benjamin; Ng, Fu Siong; Peters, Nicholas S; Toumazou, Christofer

    2017-07-01

    This paper describes the development of an array of individually addressable pH sensitive microneedles using injection moulding and their integration within a portable device for real-time wireless recording of pH distributions in biological samples. The fabricated microneedles are subjected to gold patterning followed by electrodeposition of iridium oxide to sensitize them to 0.07 units of pH change. Miniaturised electronics suitable for the sensors readout, analog-to-digital conversion and wireless transmission of the potentiometric data are embodied within the device, enabling it to measure real-time pH of soft biological samples such as muscles. In this paper, real-time recording of the cardiac pH distribution, during ischemia followed by reperfusion cycles in cardiac muscles of male Wistar rats has been demonstrated by using the microneedle array.

  15. Effects of high medium pH on growth, metabolism and transport in Saccharomyces cerevisiae.

    Science.gov (United States)

    Peña, Antonio; Sánchez, Norma Silvia; Álvarez, Helber; Calahorra, Martha; Ramírez, Jorge

    2015-03-01

    Growth of Saccharomyces cerevisiae stopped by maintaining the pH of the medium in a pH-stat at pH 8.0 or 9.0. Studying its main physiological capacities and comparing cells after incubation at pH 6.0 vs. 8.0 or 9.0, we found that (a) fermentation was moderately decreased by high pH and respiration was similar and sensitive to the addition of an uncoupler, (b) ATP and glucose-6-phosphate levels upon glucose addition increased to similar levels and (c) proton pumping and K(+) transport were also not affected; all this indicating that energy mechanisms were preserved. Growth inhibition at high pH was also not due to a significant lower amino acid transport by the cells or incorporation into proteins. The cell cycle stopped at pH 9.0, probably due to an arrest as a result of adjustments needed by the cells to contend with the changes under these conditions, and microarray experiments showed some relevant changes to this response. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permission@oup.com.

  16. Business cycles and mortality: results from Swedish microdata.

    Science.gov (United States)

    Gerdtham, Ulf-G; Johannesson, Magnus

    2005-01-01

    We assess the relationship between business cycles and mortality risk using a large individual level data set on over 40,000 individuals in Sweden who were followed for 10-16 years (leading to over 500,000 person-year observations). We test the effect of six alternative business cycle indicators on the mortality risk: the unemployment rate, the notification rate, the deviation from the GDP trend, the GDP change, the industry capacity utilization, and the industry confidence indicator. For men we find a significant countercyclical relationship between the business cycle and the mortality risk for four of the indicators and a non-significant effect for the other two indicators. For women we cannot reject the null hypothesis of no effect for any of the business cycle indicators.

  17. Proton cycling, buffering, and reaction stoichiometry in natural waters

    NARCIS (Netherlands)

    Hofmann, A.F.; Middelburg, J.J.; Soetaert, K.; Wolf-Gladrow, D.A.; Meysman, F.J.R.

    2010-01-01

    Ongoing acidification of the global ocean necessitates a solid understanding of how biogeochemical processes are driving proton cycling and observed pH changes in natural waters. The standard way of calculating the pH evolution of an aquatic system is to specify first how biogeochemical processes

  18. White poplar (Populus alba L. - Litter impact on chemical and biochemical parameters related to nitrogen cycle in contaminated soils

    Directory of Open Access Journals (Sweden)

    Paula Madejon

    2014-04-01

    Full Text Available Aim of study: The aim of this study was to determine the effect of litter from Populus alba on chemical and biochemical properties related to the N cycle in soils with different pH values and trace element contents. We hypothesized that this litter would influence several parameters related to the N cycle and consequently to soil health.Area of study: we collected two reforested contaminated soils of different pH values (AZ pH 7.23 and DO pH = 2.66 and a non-contaminated soil (RHU pH 7.19.Materials and methods: Soil samples were placed in 2,000 cm3 microcosms and were incubated for 40 weeks in controlled conditions. Each soil was mixed with its corresponding litter, and soils without litter were also tested for comparison. Ammonium (NH4+-N and nitrate (NO3–-N content, potential nitrification rate (PNR, microbial biomass nitrogen (MBN, protease activity, and several chemical properties such as pH, available trace element concentrations (extracted with 0.01 M CaCl2 were determined at different times of incubation.Main results: Values of available trace elements did not vary during the incubation and were always higher in acid soil. In neutral soils litter presence increased values of Kjeldahl-N, NO3–-N content, potential nitrification rate (PNR, microbial biomass nitrogen (MBN and protease activity. Presence of trace elements in neutral soils did not alter the parameters studied. However, acidic pH and high content of available trace elements strongly affected NH4+-N andNO3–-N, microbial biomass N and protease activity.Research highlights: Our results showed the negative effect of the acidity and trace element availability in parameters related with the N-cycle.Key words: microbial biomass N; protease activity; soil pH; N mineralization; nitrification; phytoremediation.

  19. Robustness of life cycle assessment results : influence of data variation and modelling choices on results for beverage packaging materials

    NARCIS (Netherlands)

    Harst-Wintraecken, van der E.J.M.

    2015-01-01

    Life cycle assessment (LCA) is a well-established method to evaluate the potential environmental impacts of product and service systems throughout their life cycles. However, it can happen that LCAs for the same product have different and even conflicting outcomes. LCA results need to be robust

  20. Significance of Phébus-FP results for plant safety in Switzerland

    International Nuclear Information System (INIS)

    Birchley, J.; Güntay, S.

    2013-01-01

    Highlights: • Prototypicality of Phebus is unique for severe accident integral code assessment. • MELCOR and SCDAP show good simulation capability. • Phebus revealed knowledge gaps concerning organic iodine source. • Complementary studies seek to reduce uncertainties. • New engineering technology is developed to resolve organic iodine issue. - Abstract: Switzerland, in common with other countries, uses source term estimates to formulate emergency plans in the unlikely event of an accident with release of activity to the environment. In the past estimates have typically been based on conservative treatments of the accident sequence, necessitated by the limited validation status of models used for the phenomena that control the reactor accident evolution. Although analyses using best-estimate tools frequently indicated substantially smaller releases – knowledge and data were insufficient to place reliance on the methods or the calculated results. The Phébus programme is unique in providing a source of integral transient data on fission product release, transport and chemical behaviour under prototypic conditions, capturing the entire portfolio of processes – transport, material and chemical – and their causal interaction. To this day, no other source of such data is available. These data provide a means to assess, improve and validate methods for source term evaluation and establish the needs for establishing new processes to mitigate the source term. There are strong synergies and complementarities between the Phébus project, the International Source Term Project, the iodine-related studies at PSI and the aerosol retention projects at PSI, and current moves toward improved management/mitigation of severe accidents. The Federal Nuclear Safety Inspectorate (ENSI), Paul Scherrer Institute (PSI) and the Swiss utilities running five nuclear power plants share in the findings. The need to strengthen the foundation on which we perform best

  1. Ionization of Rydberg atoms by the kicks of half-cycle pulses

    Indian Academy of Sciences (India)

    Rydberg atom; half-cycle pulses; ionization; quantum mechanical model. ... packet which represents a non-stationary quantum state formed by coherent ...... Wetzels, Impulsive interactions of half cycle pulse radiation with Rydberg atoms, Ph.D.

  2. Coral calcifying fluid pH is modulated by seawater carbonate chemistry not solely seawater pH.

    Science.gov (United States)

    Comeau, S; Tambutté, E; Carpenter, R C; Edmunds, P J; Evensen, N R; Allemand, D; Ferrier-Pagès, C; Tambutté, S; Venn, A A

    2017-01-25

    Reef coral calcification depends on regulation of pH in the internal calcifying fluid (CF) in which the coral skeleton forms. However, little is known about calcifying fluid pH (pH CF ) regulation, despite its importance in determining the response of corals to ocean acidification. Here, we investigate pH CF in the coral Stylophora pistillata in seawater maintained at constant pH with manipulated carbonate chemistry to alter dissolved inorganic carbon (DIC) concentration, and therefore total alkalinity (A T ). We also investigate the intracellular pH of calcifying cells, photosynthesis, respiration and calcification rates under the same conditions. Our results show that despite constant pH in the surrounding seawater, pH CF is sensitive to shifts in carbonate chemistry associated with changes in [DIC] and [A T ], revealing that seawater pH is not the sole driver of pH CF Notably, when we synthesize our results with published data, we identify linear relationships of pH CF with the seawater [DIC]/[H + ] ratio, [A T ]/ [H + ] ratio and [[Formula: see text

  3. The chemistry, physiology and pathology of pH in cancer.

    Science.gov (United States)

    Swietach, Pawel; Vaughan-Jones, Richard D; Harris, Adrian L; Hulikova, Alzbeta

    2014-03-19

    Cell survival is conditional on the maintenance of a favourable acid-base balance (pH). Owing to intensive respiratory CO2 and lactic acid production, cancer cells are exposed continuously to large acid-base fluxes, which would disturb pH if uncorrected. The large cellular reservoir of H(+)-binding sites can buffer pH changes but, on its own, is inadequate to regulate intracellular pH. To stabilize intracellular pH at a favourable level, cells control trans-membrane traffic of H(+)-ions (or their chemical equivalents, e.g. ) using specialized transporter proteins sensitive to pH. In poorly perfused tumours, additional diffusion-reaction mechanisms, involving carbonic anhydrase (CA) enzymes, fine-tune control extracellular pH. The ability of H(+)-ions to change the ionization state of proteins underlies the exquisite pH sensitivity of cellular behaviour, including key processes in cancer formation and metastasis (proliferation, cell cycle, transformation, migration). Elevated metabolism, weakened cell-to-capillary diffusive coupling, and adaptations involving H(+)/H(+)-equivalent transporters and extracellular-facing CAs give cancer cells the means to manipulate micro-environmental acidity, a cancer hallmark. Through genetic instability, the cellular apparatus for regulating and sensing pH is able to adapt to extracellular acidity, driving disease progression. The therapeutic potential of disturbing this sequence by targeting H(+)/H(+)-equivalent transporters, buffering or CAs is being investigated, using monoclonal antibodies and small-molecule inhibitors.

  4. White popular (Populus alba L.) - Litter impact on chemical and biochemical parameters related to nitrogen cycle in contaminated soils

    Energy Technology Data Exchange (ETDEWEB)

    Ciadamidaro, L.; Madejon, P.; Cabrera, F.; Madejon, E.

    2014-06-01

    Aim of study: The aim of this study was to determine the effect of litter from Populus alba on chemical and biochemical properties related to the N cycle in soils with different pH values and trace element contents. We hypothesized that this litter would influence several parameters related to the N cycle and consequently to soil health. Area of study: we collected two reforested contaminated soils of different pH values (AZ pH 7.23 and DO pH 2.66) and a non-contaminated soil (RHU pH 7.19). Materials and methods: Soil samples were placed in 2,000 cm{sup 3} microcosms and were incubated for 40 weeks in controlled conditions. Each soil was mixed with its corresponding litter, and soils without litter were also tested for comparison. Ammonium (NH{sub 4}{sup 4}+-N) and nitrate (NO{sub 3}{sup -} -N) content, potential nitrification rate (PNR), microbial biomass nitrogen (MBN), protease activity, and several chemical properties such as pH, available trace element concentrations (extracted with 0.01 M CaCl{sub 2}) were determined at different times of incubation. Main results: Values of available trace elements did not vary during the incubation and were always higher in acid soil. In neutral soils litter presence increased values of Kjeldahl-N, NO{sub 3} –-N content, potential nitrification rate (PNR), microbial biomass nitrogen (MBN) and protease activity. Presence of trace elements in neutral soils did not alter the parameters studied. However, acidic pH and high content of available trace elements strongly affected NH{sub 4}{sup +}-N and NO{sub 3}{sup -} -N, microbial biomass N and protease activity. Research highlights: Our results showed the negative effect of the acidity and trace element availability in parameters related with the N-cycle. (Author)

  5. Correlation between TCA cycle flux and glucose uptake rate during respiro-fermentative growth of Saccharomyces cerevisiae.

    Science.gov (United States)

    Heyland, Jan; Fu, Jianan; Blank, Lars M

    2009-12-01

    Glucose repression of the tricarboxylic acid (TCA) cycle in Saccharomyces cerevisiae was investigated under different environmental conditions using (13)C-tracer experiments. Real-time quantification of the volatile metabolites ethanol and CO(2) allowed accurate carbon balancing. In all experiments with the wild-type, a strong correlation between the rates of growth and glucose uptake was observed, indicating a constant yield of biomass. In contrast, glycerol and acetate production rates were less dependent on the rate of glucose uptake, but were affected by environmental conditions. The glycerol production rate was highest during growth in high-osmolarity medium (2.9 mmol g(-1) h(-1)), while the highest acetate production rate of 2.1 mmol g(-1) h(-1) was observed in alkaline medium of pH 6.9. Under standard growth conditions (25 g glucose l(-1) , pH 5.0, 30 degrees C) S. cerevisiae had low fluxes through the pentose phosphate pathway and the TCA cycle. A significant increase in TCA cycle activity from 0.03 mmol g(-1) h(-1) to about 1.7 mmol g(-1) h(-1) was observed when S. cerevisiae grew more slowly as a result of environmental perturbations, including unfavourable pH values and sodium chloride stress. Compared to experiments with high glucose uptake rates, the ratio of CO(2) to ethanol increased more than 50 %, indicating an increase in flux through the TCA cycle. Although glycolysis and the ethanol production pathway still exhibited the highest fluxes, the net flux through the TCA cycle increased significantly with decreasing glucose uptake rates. Results from experiments with single gene deletion mutants partially impaired in glucose repression (hxk2, grr1) indicated that the rate of glucose uptake correlates with this increase in TCA cycle flux. These findings are discussed in the context of regulation of glucose repression.

  6. Abstract of results of safety study. Nuclear fuel cycle field in fiscal 2003

    International Nuclear Information System (INIS)

    2004-11-01

    This report descried the results of studies of nuclear fuel cycle field (nuclear fuel facilities, seismic design, all subjects of environmental radiation and waste disposal, and subjects on nuclear fuel cycle in probabilistic safety assessment) in fiscal 2003 on the basis of the principle project of safety study (from fiscal 2001 to 2005). It consists of four chapters; the first chapter is outline of the principle of project, the second is objects and subjects of safety study in the nuclear fuel cycle field, the third list of questionnaire of results of safety study and the forth investigation of results of safety study in fiscal 2003. There are 49 lists, which include 22 reports on the nuclear fuel facility, one on the seismic design, 4 on the probabilistic safety assessment, 7 on the environmental radiation and 15 on the waste disposal. (S.Y.)

  7. Plant-Sediment Interactions in Salt Marshes – An Optode Imaging Study of O2, pH, and CO2 Gradients in the Rhizosphere

    Directory of Open Access Journals (Sweden)

    Ketil Koop-Jakobsen

    2018-05-01

    Full Text Available In many wetland plants, belowground transport of O2 via aerenchyma tissue and subsequent O2 loss across root surfaces generates small oxic root zones at depth in the rhizosphere with important consequences for carbon and nutrient cycling. This study demonstrates how roots of the intertidal salt-marsh plant Spartina anglica affect not only O2, but also pH and CO2 dynamics, resulting in distinct gradients of O2, pH, and CO2 in the rhizosphere. A novel planar optode system (VisiSens TD®, PreSens GmbH was used for taking high-resolution 2D-images of the O2, pH, and CO2 distribution around roots during alternating light–dark cycles. Belowground sediment oxygenation was detected in the immediate vicinity of the roots, resulting in oxic root zones with a 1.7 mm radius from the root surface. CO2 accumulated around the roots, reaching a concentration up to threefold higher than the background concentration, and generally affected a larger area within a radius of 12.6 mm from the root surface. This contributed to a lowering of pH by 0.6 units around the roots. The O2, pH, and CO2 distribution was recorded on the same individual roots over diurnal light cycles in order to investigate the interlinkage between sediment oxygenation and CO2 and pH patterns. In the rhizosphere, oxic root zones showed higher oxygen concentrations during illumination of the aboveground biomass. In darkness, intraspecific differences were observed, where some plants maintained oxic root zones in darkness, while others did not. However, the temporal variation in sediment oxygenation was not reflected in the temporal variations of pH and CO2 around the roots, which were unaffected by changing light conditions at all times. This demonstrates that plant-mediated sediment oxygenation fueling microbial decomposition and chemical oxidation has limited impact on the dynamics of pH and CO2 in S. anglica rhizospheres, which may in turn be controlled by other processes such as root

  8. Determination of cell cycle phases in live B16 melanoma cells using IRMS.

    Science.gov (United States)

    Bedolla, Diana E; Kenig, Saša; Mitri, Elisa; Ferraris, Paolo; Marcello, Alessandro; Grenci, Gianluca; Vaccari, Lisa

    2013-07-21

    The knowledge of cell cycle phase distribution is of paramount importance for understanding cellular behaviour under normal and stressed growth conditions. This task is usually assessed using Flow Cytometry (FC) or immunohistochemistry. Here we report on the use of FTIR microspectroscopy in Microfluidic Devices (MD-IRMS) as an alternative technique for studying cell cycle distribution in live cells. Asynchronous, S- and G0-synchronized B16 mouse melanoma cells were studied by running parallel experiments based on MD-IRMS and FC using Propidium Iodide (PI) staining. MD-IRMS experiments have been done using silicon-modified BaF2 devices, where the thin silicon layer prevents BaF2 dissolution without affecting the transparency of the material and therefore enabling a better assessment of the Phosphate I (PhI) and II (PhII) bands. Hierarchical Cluster Analysis (HCA) of cellular microspectra in the 1300-1000 cm(-1) region pointed out a distribution of cells among clusters, which is in good agreement with FC results among G0/G1, S and G2/M phases. The differentiation is mostly driven by the intensity of PhI and PhII bands. In particular, PhI almost doubles from the G0/G1 to G2/M phase, in agreement with the trend followed by nucleic acids during cellular progression. MD-IRMS is then proposed as a powerful method for the in situ determination of the cell cycle stage of an individual cell, without any labelling or staining, which gives the advantage of possibly monitoring specific cellular responses to several types of stimuli by clearly separating the spectral signatures related to the cellular response from those of cells that are normally progressing.

  9. A PhD is a PhD is a PhD

    OpenAIRE

    Ostrow, Deborah Anne

    2017-01-01

    A PhD is a PhD is a PhD is a practice-based project that interrogates the process of an artist undertaking PhD research under established criteria. It consists of an exegesis, an original screenplay, and a digital film made for online viewing, with images drawn from a range of documentaries and films found on YouTube. They have been dissected, re-assembled and then re-embedded to YouTube. The source material covers topics such as medicalization of madness, the conspicuous appropriation of uni...

  10. Differential gene expression in tomato fruit and Colletotrichum gloeosporioides during colonization of the RNAi-SlPH tomato line with reduced fruit acidity and higher pH.

    Science.gov (United States)

    Barad, Shiri; Sela, Noa; Dubey, Amit K; Kumar, Dilip; Luria, Neta; Ment, Dana; Cohen, Shahar; Schaffer, Arthur A; Prusky, Dov

    2017-08-04

    The destructive phytopathogen Colletotrichum gloeosporioides causes anthracnose disease in fruit. During host colonization, it secretes ammonia, which modulates environmental pH and regulates gene expression, contributing to pathogenicity. However, the effect of host pH environment on pathogen colonization has never been evaluated. Development of an isogenic tomato line with reduced expression of the gene for acidity, SlPH (Solyc10g074790.1.1), enabled this analysis. Total RNA from C. gloeosporioides colonizing wild-type (WT) and RNAi-SlPH tomato lines was sequenced and gene-expression patterns were compared. C. gloeosporioides inoculation of the RNAi-SlPH line with pH 5.96 compared to the WT line with pH 4.2 showed 30% higher colonization and reduced ammonia accumulation. Large-scale comparative transcriptome analysis of the colonized RNAi-SlPH and WT lines revealed their different mechanisms of colonization-pattern activation: whereas the WT tomato upregulated 13-LOX (lipoxygenase), jasmonic acid and glutamate biosynthesis pathways, it downregulated processes related to chlorogenic acid biosynthesis II, phenylpropanoid biosynthesis and hydroxycinnamic acid tyramine amide biosynthesis; the RNAi-SlPH line upregulated UDP-D-galacturonate biosynthesis I and free phenylpropanoid acid biosynthesis, but mainly downregulated pathways related to sugar metabolism, such as the glyoxylate cycle and L-arabinose degradation II. Comparison of C. gloeosporioides gene expression during colonization of the WT and RNAi-SlPH lines showed that the fungus upregulates ammonia and nitrogen transport and the gamma-aminobutyric acid metabolic process during colonization of the WT, while on the RNAi-SlPH tomato, it mainly upregulates the nitrate metabolic process. Modulation of tomato acidity and pH had significant phenotypic effects on C. gloeosporioides development. The fungus showed increased colonization on the neutral RNAi-SlPH fruit, and limited colonization on the WT acidic fruit

  11. PhD on Track – designing learning for PhD students

    Directory of Open Access Journals (Sweden)

    Gunhild Austrheim

    2013-12-01

    Full Text Available Three years ago we started the project "Information Management for Knowledge Creation". The project was initiated to create online information literacy modules for PhD students. The result of our endeavours, PhD on Track, will be launched in May 2013. The initial stage of the project was mapping out the information behaviour of PhD students, as well as what services they require from the library through a literature review and a focus group study. The findings of these inquiries formed the knowledge base from which we developed our information literacy modules. Our paper will focus on the interaction between content production and user testing when creating PhD on Track. Methods: User testing has been employed throughout the production stage. We have tested navigation and organisation of the web site, content and usability. The project team have conducted expert testing. Analysis: The results from our user testing have played an important part in decisions concerning content production. Our working hypothesis was that the PhD students would want an encyclopaedic website, a place to quickly find answers. However, the user tests revealed that PhD students understood and expected the website to be learning modules. Conclusions: The PhD students in the tests agreed that a site such as this would be useful, especially to new PhD students. They also liked the design, but had some qualms with the level of information. They preferred shorter text, but with more depth. The students would likewise have preferred more practical examples, more illustrations and more discipline specific information. The current content of PhD on Track reflects the feedback from the user testing. We have retained initial ideas such as one section for reviewing and discovering research literature and one section for publishing PhD research work. In addition, we have included more practical examples to indicate efficient workflows or relevant actions in context. Illustrations

  12. Effects of the menstrual cycle phases on the tilt testing results in vasovagal patients.

    Science.gov (United States)

    Zyśko, Dorota; Gajek, Jacek; Terpiłowski, Lukasz; Agrawal, Anil Kumar; Wróblewski, Paweł; Rudnicki, Jerzy

    2012-08-01

    The aim of the study was to assess the distribution of positive tilt testing (TT) throughout the menstrual cycle and to determine if the phase of menstrual cycle contributes to the duration of the loss of consciousness. TT results of 183 premenopausal women, aged 29.5 ± 9.8 years, were studied. The menstrual cycle was divided into four phases based on the first day of the last menstrual bleeding: perimenstrual (M), preovulatory (F), periovulatory (O) and postovulatory (L). Positive TT results were equally distributed. In patients with TT in O phase, the highest percentage of NTG provocation was needed. Patients in L phase had significantly lower incidence of cardioinhibitory reaction. The longest duration of loss of consciousness was in the M phase. Multiple regression analysis revealed that the duration of loss of consciousness during positive TT was significantly associated with higher number of syncopal events, TT performed in M phase and lower heart rate at TT termination. Cardiodepressive type of neurocardiogenic reaction was more frequent during M and O phase than during L phase. The distribution of positive TT results as well as syncope and presyncope does not differ throughout the menstrual cycle. Diagnostic TT in premenopausal women with unexplained syncope could be performed irrespective of the phase of menstrual cycle. TT has similar sensitivity throughout the menstrual cycle. During the postovulatory phase, cardioinhibitory reaction is less frequent than in M and O phases. The duration of loss of consciousness is longer during the M phase of the menstrual cycle independently of the higher syncope number and lower heart rate at TT termination.

  13. Elevated-constant pH control assessment at TXU's Comanche peak steam electric station

    International Nuclear Information System (INIS)

    Fellers, B.; Perkins, D.; Bosma, J.; Deshon, J.

    2002-01-01

    Industry experience with axial offset anomaly (AOA) has raised the importance of crud management strategies. Elevated-constant pH control is recognized as one potential solution. Additionally, minimizing radiation fields remains a high industry goal which is supported by this strategy. An investigation of industry experience and experimental data has supported a strategy of constant at-temperature pH of 7.4, requiring as much as 6-ppm lithium at the beginning-of-cycle (BOC). This approach, in a modern high temperature plant with high boron requirements, necessitated a careful assessment of potential risk for increased susceptibility to corrosion for both fuel cladding and RCS structural materials. This paper presents results of the assessment for Comanche peak steam electric station (CPSES) and plans for a demonstration of this practice. (author)

  14. PCR cycles above routine numbers do not compromise high-throughput DNA barcoding results.

    Science.gov (United States)

    Vierna, J; Doña, J; Vizcaíno, A; Serrano, D; Jovani, R

    2017-10-01

    High-throughput DNA barcoding has become essential in ecology and evolution, but some technical questions still remain. Increasing the number of PCR cycles above the routine 20-30 cycles is a common practice when working with old-type specimens, which provide little amounts of DNA, or when facing annealing issues with the primers. However, increasing the number of cycles can raise the number of artificial mutations due to polymerase errors. In this work, we sequenced 20 COI libraries in the Illumina MiSeq platform. Libraries were prepared with 40, 45, 50, 55, and 60 PCR cycles from four individuals belonging to four species of four genera of cephalopods. We found no relationship between the number of PCR cycles and the number of mutations despite using a nonproofreading polymerase. Moreover, even when using a high number of PCR cycles, the resulting number of mutations was low enough not to be an issue in the context of high-throughput DNA barcoding (but may still remain an issue in DNA metabarcoding due to chimera formation). We conclude that the common practice of increasing the number of PCR cycles should not negatively impact the outcome of a high-throughput DNA barcoding study in terms of the occurrence of point mutations.

  15. Increasing PhD students’ employability by focusing on the academic entrepreneurship. The analysis of the entrepreneurial competences

    Directory of Open Access Journals (Sweden)

    Sabina Hodzic

    2016-05-01

    Full Text Available The aim of the present study was to explore the perspective for entrepreneurship among PhD students coming from variety of disciplines. More precisely, to identify the most important entrepreneurial competences for succeeding in the entrepreneurial venture, to explore whether these competences are being developed during the 3rd cycle studies, and to explore the entrepreneurial intentions of the future doctors. In order to choose the most important entrepreneurial competences, individual semi-structured interviews with ten entrepreneurs from different fields were conducted. In addition, the importance of each competence was evaluated in form of the questionnaire, by seventeen entrepreneurs. After the qualitative and quantitative analysis of the interviews and the questionnaire, 20 competences were selected as the most important entrepreneurial competences. These 20 competences were then evaluated by 50 PhD students from different fields of study. They evaluated the importance of each entrepreneurial competence, the level of its development during their PhD studies, and indicated their entrepreneurial intentions after finishing the PhD. The most important and the most developed competences are presented in the results. In addition, the results showed relatively high entrepreneurial intentions in case of not finding a job after the PhD and in general. These results imply the need for incorporating some sort of entrepreneurial training and the development of entrepreneurial competences adapted to each subject area during the PhD studies.

  16. Responses of genes involved in cell cycle control to diverse DNA damaging chemicals in human lung adenocarcinoma A549 cells

    Directory of Open Access Journals (Sweden)

    Gooderham Nigel J

    2005-08-01

    Full Text Available Abstract Background Many anticancer agents and carcinogens are DNA damaging chemicals and exposure to such chemicals results in the deregulation of cell cycle progression. The molecular mechanisms of DNA damage-induced cell cycle alteration are not well understood. We have studied the effects of etoposide (an anticancer agent, cryptolepine (CLP, a cytotoxic alkaloid, benzo [a]pyrene (BaP, a carcinogenic polycyclic aromatic hydrocarbon and 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP, a cooked-meat derived carcinogen on the expression of cell cycle regulatory genes to understand the molecular mechanisms of the cell cycle disturbance. Results A549 cells were treated with DMSO or chemicals for up to 72 h and periodically sampled for cell cycle analysis, mRNA and protein expression. DMSO treated cells showed a dominant G1 peak in cell cycle at all times examined. Etoposide and CLP both induced G2/M phase arrest yet the former altered the expression of genes functioning at multiple phases, whilst the latter was more effective in inhibiting the expression of genes in G2-M transition. Both etoposide and CLP induced an accumulation of p53 protein and upregulation of p53 transcriptional target genes. Neither BaP nor PhIP had substantial phase-specific cell cycle effect, however, they induced distinctive changes in gene expression. BaP upregulated the expression of CYP1B1 at 6–24 h and downregulated many cell cycle regulatory genes at 48–72 h. By contrast, PhIP increased the expression of many cell cycle regulatory genes. Changes in the expression of key mRNAs were confirmed at protein level. Conclusion Our experiments show that DNA damaging agents with different mechanisms of action induced distinctive changes in the expression pattern of a panel of cell cycle regulatory genes. We suggest that examining the genomic response to chemical exposure provides an exceptional opportunity to understand the molecular mechanism involved in cellular

  17. The mTOR inhibitor, everolimus (RAD001), overcomes resistance to imatinib in quiescent Ph-positive acute lymphoblastic leukemia cells

    International Nuclear Information System (INIS)

    Kuwatsuka, Y; Minami, M; Minami, Y; Sugimoto, K; Hayakawa, F; Miyata, Y; Abe, A; Goff, D J; Kiyoi, H; Naoe, T

    2011-01-01

    In Ph-positive (Ph + ) leukemia, the quiescent cell state is one of the reasons for resistance to the BCR-ABL-kinase inhibitor, imatinib. In order to examine the mechanisms of resistance due to quiescence and the effect of the mammalian target of rapamycin inhibitor, everolimus, for such a resistant population, we used Ph + acute lymphoblastic leukemia patient cells serially xenotransplanted into NOD/SCID/IL2rγ null (NOG) mice. Spleen cells from leukemic mice showed a higher percentage of slow-cycling G 0 cells in the CD34 + CD38 − population compared with the CD34 + CD38 + and CD34 − populations. After ex vivo imatinib treatment, more residual cells were observed in the CD34 + CD38 − population than in the other populations. Although slow-cycling G 0 cells were insensitive to imatinib in spite of BCR-ABL and CrkL dephosphorylation, combination treatment with everolimus induced substantial cell death, including that of the CD34 + CD38 − population, with p70-S6 K dephosphorylation and decrease of MCL-1 expression. The leukemic non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mouse system with the in vivo combination treatment with imatinib and everolimus showed a decrease of tumor burden including CD34 + cells. These results imply that treatment with everolimus can overcome resistance to imatinib in Ph + leukemia due to quiescence

  18. The influence of storage time and pH variation on water sorption by different composite resins.

    Science.gov (United States)

    Gusmão, George Mário de Araújo Silva; De Queiroz, Thiago Vinicius Veras; Pompeu, Guilherme Ferrer; Menezes Filho, Paulo Fonseca; da Silva, Cláudio Heliomar Vicente

    2013-01-01

    The objective of this work was to assess the influence of storage time and pH cycling on water sorption by different composite resins. Nine resin brands were selected and divided into groups: G1-ROK (SDI), G2-ICE (SDI), G3-GLACIER (SDI), G4-Z350 (3M/ESPE), G5-Z250 (3M/ESPE), G6-TPH 3 (DENTSPLY), G7-ESTHET X (DENTSPLY), G8-SUPRAFILL (SSWHITE), and G9-MASTERFILL (BIODINΒMICS). Ninety specimens, ten per group, were obtained using an aluminum matrix. Specimens measured 10 mm diameter × 2 mm width. The groups were divided into subgroups according to the immersion solution: A - control (n = 05) stored in artificial saliva pH = 7.0 and B-test (n = 05) submitted to seven consecutive days of pH cycling (cariogenic challenger) that consisted of immersion in a pH° = 4.3 solution for 6 h followed by immersion in a pH¹ =7.0 solution for 18 h and stored in artificial saliva pH = 7.0 until the end of the experiment. The specimens were weighed on six occasions: T 0 (after fabrication), T 1 (24 h), T 2 (7 days), T 3 (15 days), T 4 (30 days), T 5 (60 days), and then analyzed. The water sorption was determined by the weight difference between the specimens at the time intervals. The mean weight gain was exactly the same for both the subgroups within group G4. The highest means for the control subgroup were found in groups: G1, G5, G7, G8, and G9. For the pH cycling subgroup, the highest means were found in G2, G3, and G6; however, significant differences between the subgroups compared to the mean-weight gain were found for G1, G5, and G7. The water sorption of composite resins is dependent upon their storage time. The pH cycling created a significant impact on resins G1, G5, and G7. The sorption and solubility of composite resins vary according to their chemical composition.

  19. Diel cycle of iron, aluminum and other heavy metals in a volcano watershed in northern Taiwan

    Science.gov (United States)

    Kao, S.

    2013-12-01

    It is well known that heavy metals in surface water show diel (24-hr) changes in concentrations due to diel biogeochemical cycle. Accordingly, it is important to have a better sampling policy for monitoring the environmental impact of heavy metals of surface water, especially volcanic and mining areas. This study investigated Tatun Volcano watershed in northern Taiwan with a 24-h sampling operation to explore the diel cycle of arsenic concentrations and discuss on the corresponding biogeochemical processes. According to the previous studies, solar energy is the main factor of diel cycles, which could have strong effects on temperature, pH, dissolved oxygen, and many other water qualities. These changes produce a series of chain reactions and finally result in the change of heavy metal concentrations. In general, diel cycle of dissolved oxygen is dominated by metabolism of aquatic plants and sunlight photoreduction in acidic stream water; therefore, the Fe and Al contents would be accordingly changed. In addition, the concentrations of heavy metals will be simultaneously modified due to the high adsorption capacity of Fe and Al hydroxides. In this study, the results of hydro chemical analysis show that creek water is characterized by higher temperature, low pH value (3.0-4.5) and high SO4content(60-400 ppm) due to the mixing of hot spring. That the pH dramatically drops in the noon demonstrates that pH is highly dependent on photoreduction. This can be confirmed by the opposite trend of Fe concentration. The high Fe content in the noon also demonstrates that the precipitation of Fe hydroxides is not dominant in the day time and Fe is mainly in dissolved and/or colloid forms. Under the situation, heavy metals are supposed to have a similar trend with Fe. However, arsenic, aluminum and rare earth elements show a quite different diel cycle from Fe and other heavy metals. It concludes that arsenic and rare earth elements may be adsorbed by Al hydroxides instead of Fe

  20. Pyrite oxidation at circumneutral pH

    Science.gov (United States)

    Moses, Carl O.; Herman, Janet S.

    1991-02-01

    Previous studies of pyrite oxidation kinetics have concentrated primarily on the reaction at low pH, where Fe(III) has been assumed to be the dominant oxidant. Studies at circumneutral pH, necessitated by effective pH buffering in some pyrite oxidation systems, have often implicitly assumed that the dominant oxidant must be dissolved oxygen (DO), owing to the diminished solubility of Fe(III). In fact, Fe(III)(aq) is an effective pyrite oxidant at circumneutral pH, but the reaction cannot be sustained in the absence of DO. The purpose of this experimental study was to ascertain the relative roles of Fe(III) and DO in pyrite oxidation at circumneutral pH. The rate of pyrite oxidation was first-order with respect to the ratio of surface area to solution volume. Direct determinations of both Fe(II) (aq)> and Fe(III) (aq) demonstrated a dramatic loss of Fe(II) from the solution phase in excess of the loss for which oxidation alone could account. Based on rate data, we have concluded that Fe(II) is adsorbed onto the pyrite surface. Furthermore, Fe(II) is preferred as an adsorbate to Fe(III), which we attribute to both electrostatic and acid-base selectivity. We also found that the rate of pyrite oxidation by either Fe(III) (aq) or DO is reduced in the presence of aqueous Fe(II), which leads us to conclude that, under most natural conditions, neither Fe(III) (aq) nor DO directly attacks the pyrite surface. The present evidence suggests a mechanism for pyrite oxidation that involves adsorbed Fe( II ) giving up electrons to DO and the resulting Fe(III) rapidly accepting electrons from the pyrite. The adsorbed Fe is, thus, cyclically oxidized and reduced, while it acts as a conduit for electrons traveling from pyrite to DO. Oxygen is transferred from the hydration sphere of the adsorbed Fe to pyrite S. The cycle of adsorbed Fe oxidation and reduction and the successive addition of oxygen to pyrite S continues until a stable sulfoxy species dissociates from the surface. Prior

  1. Advanced fuel cycle cost estimation model and its cost estimation results for three nuclear fuel cycles using a dynamic model in Korea

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sungki, E-mail: sgkim1@kaeri.re.kr [Korea Atomic Energy Research Institute, 1045 Daedeokdaero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Ko, Wonil [Korea Atomic Energy Research Institute, 1045 Daedeokdaero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Youn, Saerom; Gao, Ruxing [University of Science and Technology, 217 Gajungro, Yuseong-gu, Daejeon 305-350 (Korea, Republic of); Bang, Sungsig, E-mail: ssbang@kaist.ac.kr [Korea Advanced Institute of Science and Technology, Department of Business and Technology Management, 291 Deahak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

    2015-11-15

    Highlights: • The nuclear fuel cycle cost using a new cost estimation model was analyzed. • The material flows of three nuclear fuel cycle options were calculated. • The generation cost of once-through was estimated to be 66.88 mills/kW h. • The generation cost of pyro-SFR recycling was estimated to be 78.06 mills/kW h. • The reactor cost was identified as the main cost driver of pyro-SFR recycling. - Abstract: The present study analyzes advanced nuclear fuel cycle cost estimation models such as the different discount rate model and its cost estimation results. To do so, an analysis of the nuclear fuel cycle cost of three options (direct disposal (once through), PWR–MOX (Mixed OXide fuel), and Pyro-SFR (Sodium-cooled Fast Reactor)) from the viewpoint of economic sense, focusing on the cost estimation model, was conducted using a dynamic model. From an analysis of the fuel cycle cost estimation results, it was found that some cost gap exists between the traditional same discount rate model and the advanced different discount rate model. However, this gap does not change the priority of the nuclear fuel cycle option from the viewpoint of economics. In addition, the fuel cycle costs of OT (Once-Through) and Pyro-SFR recycling based on the most likely value using a probabilistic cost estimation except for reactor costs were calculated to be 8.75 mills/kW h and 8.30 mills/kW h, respectively. Namely, the Pyro-SFR recycling option was more economical than the direct disposal option. However, if the reactor cost is considered, the economic sense in the generation cost between the two options (direct disposal vs. Pyro-SFR recycling) can be changed because of the high reactor cost of an SFR.

  2. [An application of the strategy results cycle to HIV/AIDS strategic planning in Latin America].

    Science.gov (United States)

    Rodríguez-García, Rosalía; Rosenberg, Hernán

    2013-07-01

    To describe the Strategy Results Cycle (SRC), a model that approaches planning as an ongoing cycle of seven phases that continually responds and adapts to existing evidence. Reliable sources were used for the preparation of databases and expenditure-costing data for resources needs analysis. The planning process 6-9 months to complete a national strategic plan that was informed by evidence, focused on results and costed. Knowledge transfer facilitated national leadership and stakeholders' participation. Between 2007 and 2011, 13 of 16 countries adopted the Strategy Results Cycle model. The evidence supported the identification of results and the expenditure-costing analysis improved budget allocation efficiency. The SRC facilitated purposeful participation and added value to previous planning approaches by connecting "thinking" and "doing" which resulted in national strategic plans that are designed by stakeholders, relevant to local conditions, and can guide implementation and resource mobilization.

  3. Redox transformations of iron at extremely low pH: fundamental and applied aspects

    OpenAIRE

    Johnson, D. Barrie; Kanao, Tadayoshi; Hedrich, Sabrina

    2012-01-01

    Many different species of acidophilic prokaryotes, widely distributed within the domains Bacteria and Archaea, can catalyze the dissimilatory oxidation of ferrous iron or reduction of ferric iron, or can do both. Microbially-mediated cycling of iron in extremely acidic environments (pH <3) is strongly influenced by the enhanced chemical stability of ferrous iron and far greater solubility of ferric iron under such conditions. Cycling of iron has been demonstrated in vitro using both pure a...

  4. Environmental responsiveness of polygalacturonic acid-based multilayers to variation of pH.

    Science.gov (United States)

    Westwood, Marta; Noel, Timothy R; Parker, Roger

    2011-02-14

    The effect of pH on the stability of layer-by-layer deposited polygalacturonic acid (PGalA)-based multilayer films prepared with the polycations poly-L-lysine, chitosan, and lysozyme is studied. The response was characterized using a quartz crystal microbalance, dual polarization interferometry, and Fourier transform infrared spectroscopy which probe multilayer thickness, density, polymer mass (composition and speciation), and hydration. All multilayers showed irreversible changes in response to pH change becoming thinner due to the partial disassembly. Preferential loss of the polycation (50-80% w/w) and relative small losses of PGaLA (10-35% w/w) occurred. The charge density on the polycation has a strong influence on the response to the acid cycle. Most of the disassembly takes place at the pH lower that pK(a) of PGaLA, indicating that this factor was crucial in determining the stability of the films. The pH challenge also revealed a polycation-dependent shift to acid pH in the PGaLA pK(a).

  5. The mTOR inhibitor, everolimus (RAD001), overcomes resistance to imatinib in quiescent Ph-positive acute lymphoblastic leukemia cells

    Energy Technology Data Exchange (ETDEWEB)

    Kuwatsuka, Y; Minami, M; Minami, Y; Sugimoto, K; Hayakawa, F; Miyata, Y; Abe, A [Department of Hematology and Oncology, Nagoya University Graduate School of Medicine, Nagoya (Japan); Goff, D J [Moores Cancer Center, University of California San Diego School of Medicine, La Jolla, CA (United States); Kiyoi, H [Department of Infectious Diseases, Nagoya University Hospital, Nagoya (Japan); Naoe, T [Department of Hematology and Oncology, Nagoya University Graduate School of Medicine, Nagoya (Japan)

    2011-05-01

    In Ph-positive (Ph{sup +}) leukemia, the quiescent cell state is one of the reasons for resistance to the BCR-ABL-kinase inhibitor, imatinib. In order to examine the mechanisms of resistance due to quiescence and the effect of the mammalian target of rapamycin inhibitor, everolimus, for such a resistant population, we used Ph{sup +} acute lymphoblastic leukemia patient cells serially xenotransplanted into NOD/SCID/IL2rγ{sup null} (NOG) mice. Spleen cells from leukemic mice showed a higher percentage of slow-cycling G{sub 0} cells in the CD34{sup +}CD38{sup −} population compared with the CD34{sup +}CD38{sup +} and CD34{sup −} populations. After ex vivo imatinib treatment, more residual cells were observed in the CD34{sup +}CD38{sup −} population than in the other populations. Although slow-cycling G{sub 0} cells were insensitive to imatinib in spite of BCR-ABL and CrkL dephosphorylation, combination treatment with everolimus induced substantial cell death, including that of the CD34{sup +}CD38{sup −} population, with p70-S6 K dephosphorylation and decrease of MCL-1 expression. The leukemic non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mouse system with the in vivo combination treatment with imatinib and everolimus showed a decrease of tumor burden including CD34{sup +} cells. These results imply that treatment with everolimus can overcome resistance to imatinib in Ph{sup +} leukemia due to quiescence.

  6. G-Quadruplex conformational change driven by pH variation with potential application as a nanoswitch.

    Science.gov (United States)

    Yan, Yi-Yong; Tan, Jia-Heng; Lu, Yu-Jing; Yan, Siu-Cheong; Wong, Kwok-Yin; Li, Ding; Gu, Lian-Quan; Huang, Zhi-Shu

    2013-10-01

    G-Quadruplex is a highly polymorphic structure, and its behavior in acidic condition has not been well studied. Circular dichroism (CD) spectra were used to study the conformational change of G-quadruplex. The thermal stabilities of the G-quadruplex were measured with CD melting. Interconversion kinetics profiles were investigated by using CD kinetics. The fluorescence of the inserted 2-Aminopurine (Ap) was monitored during pH change and acrylamide quenching, indicating the status of the loop. Proton NMR was adopted to help illustrate the change of the conformation. G-Quadruplex of specific loop was found to be able to transform upon pH variation. The transformation was resulted from the loop rearrangement. After screening of a library of diverse G-quadruplex, a sequence exhibiting the best transformation property was found. A pH-driven nanoswitch with three gears was obtained based on this transition cycle. Certain G-quadruplex was found to go through conformational change at low pH. Loop was the decisive factor controlling the interconversion upon pH variation. G-Quadruplex with TT central loop could be converted in a much milder condition than the one with TTA loop. It can be used to design pH-driven nanodevices such as a nanoswitch. These results provide more insights into G-quadruplex polymorphism, and also contribute to the design of DNA-based nanomachines and logic gates. © 2013.

  7. pH gradients in the diffusive boundary layer of subarctic macrophytes

    KAUST Repository

    Hendriks, Iris E.; Duarte, Carlos M.; Marbà , Nú ria; Krause-Jensen, Dorte

    2017-01-01

    Highly productive macrophytes produce diurnal and seasonal cycles in CO concentrations modulated by metabolic activity, which cause discrepancies between pH in the bulk water and near seaweed blades, especially when entering the diffusion boundary layer (DBL). Calcifying epiphytic organisms living in this environment are therefore exposed to a different pH environment than that of the water column. To evaluate the actual pH environment on blade surfaces, we measured the thickness of the DBL and pH gradients within it for six subarctic macrophytes: Fucus vesiculosus, Ascophyllum nodosum, Ulva lactuca, Zostera marina, Saccharina longicruris, and Agarum clathratum. We measured pH under laboratory conditions at ambient temperatures (2–3 °C) and slow, stable flow over the blade surface at five light intensities (dark, 30, 50, 100 and 200 µmol photons m s). Boundary layer thickness ranged between 511 and 1632 µm, while the maximum difference in pH (∆pH) between the blade surface and the water column ranged between 0.4 ± 0.14 (average ± SE; Zostera) and 1.2 ± 0.13 (average ± SE; Ulva) pH units. These differences in pH are larger than predictions for pH changes in the bulk water by the end of the century. A simple quadratic model best described the relationship between light intensity and maximum ∆pH, pointing at relatively low optimum PAR of between 28 and 139 µmol photons m s to reach maximum ∆pH. Elevated pH at the blade surface may provide chemical “refugia” for calcifying epiphytic organisms, especially during summer at higher latitudes where photoperiods are long.

  8. pH gradients in the diffusive boundary layer of subarctic macrophytes

    KAUST Repository

    Hendriks, Iris E.

    2017-06-20

    Highly productive macrophytes produce diurnal and seasonal cycles in CO concentrations modulated by metabolic activity, which cause discrepancies between pH in the bulk water and near seaweed blades, especially when entering the diffusion boundary layer (DBL). Calcifying epiphytic organisms living in this environment are therefore exposed to a different pH environment than that of the water column. To evaluate the actual pH environment on blade surfaces, we measured the thickness of the DBL and pH gradients within it for six subarctic macrophytes: Fucus vesiculosus, Ascophyllum nodosum, Ulva lactuca, Zostera marina, Saccharina longicruris, and Agarum clathratum. We measured pH under laboratory conditions at ambient temperatures (2–3 °C) and slow, stable flow over the blade surface at five light intensities (dark, 30, 50, 100 and 200 µmol photons m s). Boundary layer thickness ranged between 511 and 1632 µm, while the maximum difference in pH (∆pH) between the blade surface and the water column ranged between 0.4 ± 0.14 (average ± SE; Zostera) and 1.2 ± 0.13 (average ± SE; Ulva) pH units. These differences in pH are larger than predictions for pH changes in the bulk water by the end of the century. A simple quadratic model best described the relationship between light intensity and maximum ∆pH, pointing at relatively low optimum PAR of between 28 and 139 µmol photons m s to reach maximum ∆pH. Elevated pH at the blade surface may provide chemical “refugia” for calcifying epiphytic organisms, especially during summer at higher latitudes where photoperiods are long.

  9. Determining pH of strip-mine spoils

    Science.gov (United States)

    W. A. Berg

    1969-01-01

    Results with the LaMotte-Morgan method for determining soil pH-or the solution modification of this method-usually agreed fairly well with the results from using a pH meter, the recognized standard. Results obtained with the Soiltex and Hellige-Truog methods often deviated somewhat from the pH meter readings; and the Hydrion papers and the Kelway pH tester often gave...

  10. Shaping the esp curriculum of an english for PhD students program: a colombian case study of questionnaire research

    Directory of Open Access Journals (Sweden)

    Gerriet Janssen

    2012-12-01

    Full Text Available This report presents the findings from an EAP curriculum development project directed towards PhD students at Colombian university.An analysis of this stakeholder group’s learning needs was conducted through questionnaire research, focusing on (a describing students’situated contexts and interests and (b obtaining data contributing towards future program development. Measures of central tendency,dispersion, and internal consistency for each section of the questionnaire are reported. Key results include these students’ strong interest inEAP programming, their language needs and experience regarding their intellectual production, and their perceived importance of differentlanguage sub-skills in both the local and international contexts. The results highlight the importance of continued evaluation cycles and theimportant role EAP coursework has for PhD students today.

  11. Effects of pH, Chloride, and Bicarbonate on Cu(I) Oxidation Kinetics at Circumneutral pH

    Science.gov (United States)

    Yuan, X.; Pham, A.; Waite, T.; Xing, G.; Rose, A.

    2012-12-01

    The redox chemistry of copper species in the upper water column plays a significant role in its speciation, transport and bioavailability. Most previous studies have focused primarily on Cu(II), principally because Cu(I) is easily oxidized to Cu(II) by oxygen or other oxidants. However, a growing body of evidence indicates that a number of potentially important reactions may lead to Cu(I) formation and result in a significant steady-state concentration of Cu(I) in natural waters. Redox reactions of Cu(I) could result in the production of reactive oxygen species (ROS), such as superoxide and hydroxyl radical, that may subsequently induce a cascade of radical-promoted reactions with other constituents in natural waters. As such, a better understanding of copper-catalysed processes that produce and consume O2- is important in furthering our insight into factors contributing to global biogeochemical cycles. In this study, the oxidation kinetics of nanomolar concentrations of Cu(I) in NaCl solutions have been investigated over the pH range 6.5-8.0.The overall apparent oxidation rate constant was strongly affected by chloride, moderately by bicarbonate and, and to a lesser extent, by pH. In the absence of bicarbonate, an equilibrium-based speciation model indicated that Cu+ and CuClOH- were the most kinetically reactive species, while the contribution of other Cu(I) species to the overall oxidation rate was minor. A kinetic model based on recognized key redox reactions for these two species further indicated that oxidation of Cu(I) by oxygen and superoxide were important reactions at all pH values and [Cl-] considered, but back reduction of Cu(II) by superoxide only became important at relatively low chloride concentrations. Bicarbonate concentrations from 2-5 mM substantially accelerated Cu(I) oxidation. Kinetic analysis over a range of bicarbonate concentrations revealed that this was due to the formation of CuCO3-, which reacts relatively rapidly with oxygen, and not

  12. Electrolyte engineering toward efficient water splitting at mild pH

    KAUST Repository

    Shinagawa, Tatsuya; Ng, Marcus Tze-Kiat; Takanabe, Kazuhiro

    2017-01-01

    The development of processes for the conversion of H2O/CO2 driven by electricity generated in renewable manners is essential to achieve sustainable energy and chemical cycles, in which the electrocatalytic oxygen evolution reaction (OER) is one of the bottlenecks. In this contribution, the influences of the electrolyte molarity and identity on OER at alkaline to neutral pH were investigated at an appreciable current density of ~10 mA cm-2, revealing (1) the clear boundary of reactant switching between H2O/OH- due to the diffusion limitation of OH- and (2) the substantial contribution of the mass transport of the buffered species in buffered mild pH conditions. These findings propose a strategy of electrolyte engineering: tuning the electrolyte properties to maximize the mass-transport flux. The concept was successfully demonstrated for OER as well as overall water electrolysis in buffered mild pH conditions, shedding light on the development of practical solar fuel production systems.

  13. Electrolyte engineering toward efficient water splitting at mild pH

    KAUST Repository

    Shinagawa, Tatsuya

    2017-08-28

    The development of processes for the conversion of H2O/CO2 driven by electricity generated in renewable manners is essential to achieve sustainable energy and chemical cycles, in which the electrocatalytic oxygen evolution reaction (OER) is one of the bottlenecks. In this contribution, the influences of the electrolyte molarity and identity on OER at alkaline to neutral pH were investigated at an appreciable current density of ~10 mA cm-2, revealing (1) the clear boundary of reactant switching between H2O/OH- due to the diffusion limitation of OH- and (2) the substantial contribution of the mass transport of the buffered species in buffered mild pH conditions. These findings propose a strategy of electrolyte engineering: tuning the electrolyte properties to maximize the mass-transport flux. The concept was successfully demonstrated for OER as well as overall water electrolysis in buffered mild pH conditions, shedding light on the development of practical solar fuel production systems.

  14. Additive influence of extracellular pH, oxygen tension, and pressure on invasiveness and survival of human osteosarcoma cells

    Directory of Open Access Journals (Sweden)

    Takao eMatsubara

    2013-07-01

    Full Text Available BACKGROUND/PURPOSE:The effects of chemical and physical interactions in the microenvironment of solid tumors have not been fully elucidated. We hypothesized that acidosis, hypoxia, and elevated interstitial fluid pressure (eIFP have additive effects on tumor cell biology and lead to more aggressive behavior during tumor progression. We investigated this phenomenon using 3 human osteosarcoma cell lines and a novel in vitro cell culture apparatus. MATERIALS AND METHODS:U2OS, SaOS, and MG63 cell lines were cultured in media adjusted to various pH levels, oxygen tension (hypoxia 2% O2, normoxia 20% O2, and hydrostatic gauge pressure (0 or 50 mm Hg. Growth rate, apoptosis, cell cycle parameters, and expression of mRNA for proteins associated with invasiveness and tumor microenvironment (CA IX, VEGF-A, HIF-1A, MMP-9, and TIMP-2 were analyzed. Levels of CA IX, HIF-1α, and MMP-9 were measured using immunofluorescence. The effect of pH on invasiveness was evaluated in a Matrigel chamber assay.RESULTS: Within the acidic–hypoxic–pressurized conditions that simulate the microenvironment at a tumor’s center, invasive genes were upregulated, but the cell cycle was downregulated. The combined influence of acidosis, hypoxia, and IFP promoted invasiveness and angiogenesis to a greater extent than did pH, pO2, or eIFP individually. Significant cell death after brief exposure to acidic conditions occurred in each cell line during acclimation to acidic media, while prolonged exposure to acidic media resulted in reduced cell death. Furthermore, 48-hour exposure to acidic conditions promoted tumor invasiveness in the Matrigel assay. CONCLUSION: Our findings demonstrate that tumor microenvironmental parameters—particularly pH, pO2, and eIFP—additively influence tumor proliferation, invasion, metabolism, and viability to enhance cell survival.

  15. KOH concentration effect on the cycle life of nickel-hydrogen cells. 4: Results of failure analyse

    Science.gov (United States)

    Lim, H. S.; Verzwyvelt, S. A.

    1989-01-01

    Effects of KOH concentrations on failure modes and mechanisms of nickel-hydrogen cells were studied using long cycled boiler plate cells containing electrolytes of various KOH concentrations ranging 21 to 36 percent. Life of these cells were up to 40,000 cycles in an accelerated low earth orbit (LEO) cycle regime at 80 percent depth of discharge. An interim life test results were reported earlier in J. Power Sources, 22, 213-220, 1988. The results of final life test, end-of-life cell performance, and teardown analyses are discussed. These teardown analyses included visual observations, measurements of nickel electrode capacity in an electrolyte-flooded cell, dimensional changes of cell components, SEM studies on cell cross section, BET surface area and pore volume distribution in cycled nickel electrodes, and chemical analyses. Cycle life of a nickel-hydrogen cell was improved tremendously as KOH concentration was decreased from 36 to 31 percent and from 31 to 26 percent while effect of further concentration decrease was complicated as described in our earlier report. Failure mode of high concentration (31 to 36 percent) cells was gradual capacity decrease, while that of low concentration (21 to 26 percent) cells was mainly formation of a soft short. Long cycled (25,000 to 40,000 cycles) nickel electrodes were expanded more than 50 percent of the initial value, but no correlation was found between this expansion and measured capacity. All electrodes cycled in low concentration (21 to 26 percent) cells had higher capacity than those cycled in high concentration (31 to 36 percent) cells.

  16. Functional photoacoustic microscopy of pH.

    Science.gov (United States)

    Chatni, Muhammad Rameez; Yao, Junjie; Danielli, Amos; Favazza, Christopher P; Maslov, Konstantin I; Wang, Lihong V

    2011-10-01

    pH is a tightly regulated indicator of metabolic activity. In mammalian systems, an imbalance of pH regulation may result from or result in serious illness. In this paper, we report photoacoustic microscopy (PAM) of a commercially available pH-sensitive fluorescent dye (SNARF-5F carboxylic acid) in tissue phantoms. We demonstrated that PAM is capable of pH imaging in absolute values at tissue depths of up to 2.0 mm, greater than possible with other forms of optical microscopy.

  17. Ubiquinone modified printed carbon electrodes for cell culture pH monitoring.

    Science.gov (United States)

    McBeth, Craig; Dughaishi, Rajaa Al; Paterson, Andrew; Sharp, Duncan

    2018-08-15

    The measurement of pH is important throughout many biological systems, but there are limited available technologies to enable its periodical monitoring in the complex, small volume, media often used in cell culture experiments across a range of disciplines. Herein, pad printed electrodes are developed and characterised through modification with: a commercially available fullerene multiwall carbon nanotube composite applied in Nafion, casting of hydrophobic ubiquinone as a pH probe to provide the electrochemical signal, and coated in Polyethylene glycol to reduce fouling and potentially enhance biocompatibility, which together are proven to enable the determination of pH in cell culture media containing serum. The ubiquinone oxidation peak position (E pa ) provided an indirect marker of pH across the applicable range of pH 6-9 (R 2 = 0.9985, n = 15) in complete DMEM. The electrochemical behaviour of these sensors was also proven to be robust; retaining their ability to measure pH in cell culture media supplemented with serum up to 20% (v/v) [encompassing the range commonly employed in cell culture], cycled > 100 times in 10% serum containing media and maintain > 60% functionality after 5 day incubation in a 10% serum containing medium. Overall, this proof of concept research highlights the potential applicability of this, or similar, electrochemical approaches to enable to detection or monitoring of pH in complex cell culture media. Copyright © 2018 Elsevier B.V. All rights reserved.

  18. Study on the reactive transient α-λ3-iodanyl-acetophenone complex in the iodine(III)/PhI(I) catalytic cycle of iodobenzene-catalyzed α-acetoxylation reaction of acetophenone by electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Wang, Hao-Yang; Zhou, Juan; Guo, Yin-Long

    2012-03-30

    Hypervalent iodine compounds are important and widely used oxidants in organic chemistry. In 2005, Ochiai reported the PhI-catalyzed α-acetoxylation reaction of acetophenone by the oxidation of PhI with m-chloroperbenzoic acid (m-CPBA) in acetic acid. However, until now, the most critical reactive α-λ(3)-iodine alkyl acetophenone intermediate (3) had not been isolated or directly detected. Electrospray ionization tandem mass spectrometry (ESI-MS/MS) was used to intercept and characterize the transient reactive α-λ(3)-iodine alkyl acetophenone intermediate in the reaction solution. The trivalent iodine species was detected when PhI and m-CPBA in acetic acid were mixed, which indicated the facile oxidation of a catalytic amount of PhI(I) to the iodine(III) species by m-CPBA. Most importantly, 3·H(+) was observed at m/z 383 from the reaction solution and this ion gave the protonated α-acetoxylation product 4·H(+) at m/z 179 in MS/MS by an intramolecular reductive elimination of PhI. These ESI-MS/MS studies showed the existence of the reactive α-λ(3)-iodine alkyl acetophenone intermediate 3 in the catalytic cycle. Moreover, the gas-phase reactivity of 3·H(+) was consistent with the proposed solution-phase reactivity of the α-λ(3)-iodine alkyl acetophenone intermediate 3, thus confirming the reaction mechanism proposed by Ochiai. Copyright © 2012 John Wiley & Sons, Ltd.

  19. Effect of Low ph on Carbohydrate Production by a Marine Planktonic Diatom (Chaetoceros muelleri)

    International Nuclear Information System (INIS)

    Thornton, D.C.O.

    2009-01-01

    Rising carbon dioxide (CO 2 ) concentrations in the atmosphere due to human activity are causing the surface ocean to become more acidic. Diatoms play a pivotal role in biogeochemical cycling and ecosystem function in the ocean. ph affected the quantum efficiency of photosystem II and carbohydrate metabolism in a planktonic diatom (Chaetoceros muelleri), representative of a widely distributed genus. In batch cultures grown at low ph, the proportion of total carbohydrate stored within the cells decreased and more dissolved carbohydrates were exuded from the cells into the surrounding medium. Changes in productivity and the way in which diatoms allocate carbon into carbohydrates may affect ecosystem function and the efficiency of the biological carbon pump in a low ph ocean.

  20. Comparison of pH Data Measured with a pH Sensor Array Using Different Data Fusion Methods

    OpenAIRE

    Yi-Hung Liao; Jung-Chuan Chou

    2012-01-01

    This paper introduces different data fusion methods which are used for an electrochemical measurement using a sensor array. In this study, we used ruthenium dioxide sensing membrane pH electrodes to form a sensor array. The sensor array was used for detecting the pH values of grape wine, generic cola drink and bottled base water. The measured pH data were used for data fusion methods to increase the reliability of the measured results, and we also compared the fusion results with other differ...

  1. Automated pH Control of Nutrient Solution in a Hydroponic Plant Growth System

    Science.gov (United States)

    Smith, B.; Dogan, N.; Aglan, H.; Mortley, D.; Loretan, P.

    1998-01-01

    Over, the years, NASA has played an important role in providing to and the development of automated nutrient delivery and monitoring, systems for growing crops hydroponically for long term space missions. One example are the systems used in the Biomass Production Chamber (BPC) at Kennedy Space Center (KSC). The current KSC monitoring system is based on an engineering workstation using standard analog/digital input/output hardware and custom written software. The monitoring system uses completely separate sensors to provide a check of control sensor accuracy and has the ability to graphically display and store data form past experiment so that they are available for data analysis [Fortson, 1992]. In many cases, growing systems have not been fitted with the kind of automated control systems as used at KSC. The Center for Food and Environmental Systems for Human Exploration of Space (CFESH) located on the campus of Tuskegee University, has effectively grown sweetpotatoes and peanuts hydroponically for the past five years. However they have adjusted the pH electrical conductivity and volume of the hydroponic nutrient solution only manually at times when the solution was to be replenished or changed out according to its protocol (e.g. one-week, two-week, or two-day cycle). But the pH of the nutrient solution flowing through the channel is neither known nor controlled between the update, change out, or replenishment period. Thus, the pH of the nutrient solution is not held at an optimum level over the span of the plant's growth cycle. To solve this dilemma, an automated system for the control and data logging of pH data relative to sweetpotato production using the nutrient film technique (NFT) has been developed, This paper discusses a microprocessor-based system, which was designed to monitor, control, and record the pH of a nutrient solution used for growing sweetpotatoes using NFT.

  2. Salivary pH: A diagnostic biomarker

    Directory of Open Access Journals (Sweden)

    Sharmila Baliga

    2013-01-01

    Full Text Available Objectives: Saliva contains a variety of host defense factors. It influences calculus formation and periodontal disease. Different studies have been done to find exact correlation of salivary biomarkers with periodontal disease. With a multitude of biomarkers and complexities in their determination, the salivary pH may be tried to be used as a quick chairside test. The aim of this study was to analyze the pH of saliva and determine its relevance to the severity of periodontal disease. Study Design: The study population consisted of 300 patients. They were divided into three groups of 100 patients each: Group A had clinically healthy gingiva, Group B who had generalized chronic gingivitis and Group C who had generalized chronic periodontitis. The randomized unstimulated saliva from each patient was collected and pH was tested. Data was analyzed statistically using analysis of variance technique. Results: The salivary pH was more alkaline for patients with generalized chronic gingivitis as compared with the control group (P = 0.001 whereas patients with generalized chronic periodontitis had more acidic pH as compared with the control group (P = 0.001. Conclusion: These results indicate a significant change in the pH depending on the severity of the periodontal condition. The salivary pH shows significant changes and thus relevance to the severity of periodontal disease. Salivary pH may thus be used as a quick chairside diagnostic biomarker.

  3. Reducing life cycle greenhouse gas emissions of corn ethanol by integrating biomass to produce heat and power at ethanol plants

    International Nuclear Information System (INIS)

    Kaliyan, Nalladurai; Morey, R. Vance; Tiffany, Douglas G.

    2011-01-01

    A life-cycle assessment (LCA) of corn ethanol was conducted to determine the reduction in the life-cycle greenhouse gas (GHG) emissions for corn ethanol compared to gasoline by integrating biomass fuels to replace fossil fuels (natural gas and grid electricity) in a U.S. Midwest dry-grind corn ethanol plant producing 0.19 hm 3 y -1 of denatured ethanol. The biomass fuels studied are corn stover and ethanol co-products [dried distillers grains with solubles (DDGS), and syrup (solubles portion of DDGS)]. The biomass conversion technologies/systems considered are process heat (PH) only systems, combined heat and power (CHP) systems, and biomass integrated gasification combined cycle (BIGCC) systems. The life-cycle GHG emission reduction for corn ethanol compared to gasoline is 38.9% for PH with natural gas, 57.7% for PH with corn stover, 79.1% for CHP with corn stover, 78.2% for IGCC with natural gas, 119.0% for BIGCC with corn stover, and 111.4% for BIGCC with syrup and stover. These GHG emission estimates do not include indirect land use change effects. GHG emission reductions for CHP, IGCC, and BIGCC include power sent to the grid which replaces electricity from coal. BIGCC results in greater reductions in GHG emissions than IGCC with natural gas because biomass is substituted for fossil fuels. In addition, underground sequestration of CO 2 gas from the ethanol plant's fermentation tank could further reduce the life-cycle GHG emission for corn ethanol by 32% compared to gasoline.

  4. Dynamic regulation of gastric surface pH by luminal pH

    OpenAIRE

    Chu, Shaoyou; Tanaka, Shin; Kaunitz, Jonathan D.; Montrose, Marshall H.

    1999-01-01

    In vivo confocal imaging of the mucosal surface of rat stomach was used to measure pH noninvasively under the mucus gel layer while simultaneously imaging mucus gel thickness and tissue architecture. When tissue was superfused at pH 3, the 25 μm adjacent to the epithelial surface was relatively alkaline (pH 4.1 ± 0.1), and surface alkalinity was enhanced by topical dimethyl prostaglandin E2 (pH 4.8 ± 0.2). Luminal pH was changed from pH 3 to pH 5 to mimic the fasted-to-fed transition in intra...

  5. In vitro synthesis and purification of PhIP-deoxyguanosine and PhIP-DNA oligomer covalent complexes

    Energy Technology Data Exchange (ETDEWEB)

    Freeman, J.

    1994-12-01

    2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a heterocyclic amine compound formed when meats are cooked at high temperatures. PhIP damages DNA by forming covalent complexes with DNA carcinogen. In an effort to understand how the binding of PhIP to DNA may cause cancer, it is important to characterize the structures of PhIP-damaged DNA molecules. Our HPLC data support fluorescence and {sup 32}P Post-labeling studies which indicate the formation of several species of 2{prime}deoxyguanosine-(dG) or oligodeoxynucleotide-PhIP adducts. The reaction of PhIP with dG resulted in a reddish precipitate that was likely the major adduct, N-(deoxyguanosin-8-yl)-PhIP (dG-C8-PhIP) adduct, with a more polar adduct fraction remaining in the supernatant. Reversed-phase HPLC analysis of the adducts in the supernatant revealed the existence of species of much shorter retention times than the dG-C8-PhIP adduct, confirming that these species are more polar than dG-C8-PhIP. At least four adducts were formed in the reaction of PhIP with DNA oligomer. HPLC analysis of the PhIP-DNA oligomer supernatant after butanol extractions revealed four unresolved peaks which spectra had maximum wavelengths between 340 and 360 nm. Though adduct peaks were not completely resolved, there was {approximately}3 minutes interval between the DNA oligomer peak and the adduct peaks. Furthermore, fluorescence emission data of the DNA oligomer-PhIP adduct solution show heterogeneous binding. The more polar PhIP adducts were fraction-collected and their structures will be solved by nuclear magnetic resonance or x-ray crystallography.

  6. Results of VVER fuel rods tests in the MIR.M1 reactor under power cycling conditions

    International Nuclear Information System (INIS)

    Burukin, A.; Izhutov, A.; Ovchinnikov, V.; Kalygin, V.; Markov, D.; Pimenov, Y.; Novikov, V.; Medvedev, A.; Nesterov, B.

    2011-01-01

    The paper presents the main results of the 50 ... 60 MWd/kgU burnup VVER fuel rods tests performed in the MIR.M1 reactor loop facilities under power cycling. The non-destructive PIE results are presented as well. A series of experiments was performed, including overall measurement of fuel rod parameters test, in one of which 300 cycles were done. Irradiation under power cycling conditions and PIE of high-burnup VVER fuel rods showed the following: 1) all fuel rods claddings preserved their integrity under irradiation at linear heat rate (LHR) higher than the NPP operating one; 2) experimental data were obtained on the axial and radial cladding strain and fission gas release (FGR) from 50 ... 60 MWd/kgU burnup VVER-440 and VVER-1000 fuel rods as well as on the kinetics of the change in these parameters and fuel temperature under the power cycling; 3) non-destructive PIE results are in a satisfactory correlation with the data obtained by means of in-pile measurement gages during irradiation. (authors)

  7. Comparison of pH Data Measured with a pH Sensor Array Using Different Data Fusion Methods

    Directory of Open Access Journals (Sweden)

    Yi-Hung Liao

    2012-09-01

    Full Text Available This paper introduces different data fusion methods which are used for an electrochemical measurement using a sensor array. In this study, we used ruthenium dioxide sensing membrane pH electrodes to form a sensor array. The sensor array was used for detecting the pH values of grape wine, generic cola drink and bottled base water. The measured pH data were used for data fusion methods to increase the reliability of the measured results, and we also compared the fusion results with other different data fusion methods.

  8. The potential of curcumin reagent as a natural pH indicator for the development of an optical pH sensor

    International Nuclear Information System (INIS)

    Rosmawani Mohammad; Musa Ahmad; Jamaluddin Mohd Daud

    2007-01-01

    The potential of curcumin reagent as a natural pH indicator for the development of an optical pH sensor was discussed in this study. Curcumin has been chosen because it has never been reported before for use in the development of an optical pH sensor. Curcumin is a coloring constituent of turmeric that giving yellow pigmentation. Curcumin showed clear color changes, for example yellow in acidic and reddish-brown in basic solutions. The color change is fast for example within 5 seconds. Results from the study showed that a linear pH range for this reagent was observed at pH 8-12 (R 2 =0.9854). Curcumin has a good photo stability with RSD value of 1.42 % for a study period of 6 months. The RSD values of the reproducibility study were found to be 1.43 % and 0.37 % for pH 9 and pH 12, respectively. Characterisation of the immobilised curcumin reagent also showed promising results, hence a good potential for use as a sensing reagent for an optical pH sensor. (author)

  9. Biological phosphorus cycling in dryland regions

    Science.gov (United States)

    Belnap, Jayne; Bunemann, Else; Oberson, Astrid; Frossard, Emmanuel

    2011-01-01

    The relatively few studies done on phosphorus (P) cycling in arid and semiarid lands (drylands) show many factors that distinguish P cycling in drylands from that in more mesic regions. In drylands, most biologically relevant P inputs and losses are from the deposition and loss of dust. Horizontal and vertical redistribution of P is an important process. P is concentrated at the soil surface and thus vulnerable to loss via erosion. High pH and CaCO3 limit P bioavailability, and low rainfall limits microbe and plant ability to free abiotically bound P via exudates, thus making it available for uptake. Many invasive plants are able to access recalcitrant P more effectively than are native plants. As P availability depends on soil moisture and temperature, climate change is expected to have large impacts on P cycling

  10. Trans-life cycle acclimation to experimental ocean acidification affects gastric pH homeostasis and larval recruitment in the sea star Asterias rubens.

    Science.gov (United States)

    Hu, Marian Y; Lein, Etienne; Bleich, Markus; Melzner, Frank; Stumpp, Meike

    2018-04-16

    Experimental simulation of near-future ocean acidification (OA) has been demonstrated to affect growth and development of echinoderm larval stages through energy allocation towards ion and pH compensatory processes. To date, it remains largely unknown how major pH regulatory systems and their energetics are affected by trans-generational exposure to near-future acidification levels. Here we used the common sea star Asterias rubens in a reciprocal transplant experiment comprising different combinations of OA scenarios, in order to study trans-generational plasticity using morphological and physiological endpoints. Acclimation of adults to pH T 7.2 (pCO 2 3500μatm) led to reductions in feeding rates, gonad weight, and fecundity. No effects were evident at moderate acidification levels (pH T 7.4; pCO 2 2000μatm). Parental pre-acclimation to pH T 7.2 for 85 days reduced developmental rates even when larvae were raised under moderate and high pH conditions, whereas pre-acclimation to pH T 7.4 did not alter offspring performance. Microelectrode measurements and pharmacological inhibitor studies carried out on larval stages demonstrated that maintenance of alkaline gastric pH represents a substantial energy sink under acidified conditions that may contribute up to 30% to the total energy budget. Parental pre-acclimation to acidification levels that are beyond the pH that is encountered by this population in its natural habitat (e.g. pH T 7.2) negatively affected larval size and development, potentially through reduced energy transfer. Maintenance of alkaline gastric pH and reductions in maternal energy reserves probably constitute the main factors for a reduced juvenile recruitment of this marine keystone species under simulated OA. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  11. Creative Cycling of News Professionals

    Directory of Open Access Journals (Sweden)

    Astrid Gynnild, PhD.

    2007-03-01

    Full Text Available The theory of creative cycling emerged from my PhD study of news professionals in Norway. The study was carried out according to classic grounded theory principles (Glaser and Strauss 1967, Glaser 1978, 1998, 2001, 2005, and the area of interest was the performance of news journalism in the multimedia age. The theory runs counter to widespread tendencies of industrial age thinking in news media. It emphasizes news professionals’ search for meaning in their daily work, and suggests that their main concern is self-fulfillment through original contribution. The dilemma and resolution, creative cycling, is a basic social process continuously going within inner and outer framings. It consists of three interrelated dimensions: productive processing, breaks and shifts and inspirational looping.

  12. Terrestrial soil pH and MAAT records based on the MBT/CBT in the southern South China Sea: implications for the atmospheric CO2 evolution in Southeast Asia

    Science.gov (United States)

    Dong, L.; Li, L.; Li, Q.; Zhang, C.

    2013-12-01

    Liang Dong1, Li Li1, Qianyu Li1,2, Chuanlun L. Zhang1,3 1State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China 2School of Earth and Environment Sciences, University of Adelaide, SA 5005, Australia 3Department of Marine Sciences, University of Georgia, Athens, GA 30602, USA The methylation index of branched tetraethers (MBT) and/or the cyclization ratio of branched tetraethers (CBT) are derived from the branched glycerol dialkyl Glycerol tetraethers (GDGTs) of bacterial origin and are widely used to reconstruct the terrestrial soil pH and mean annual air temperature (MAAT); however, these proxies are less frequently used in the oceanic settings. Here we provide the first high resolution records of soil pH and MAAT since the last glacial maximum based on the sedimentary core of MD05-2896 in the southern South China Sea. The MAAT record exhibited typical glacial and interglacial cycles and was consistent with the winter insolation variation. The pH values were lower (6.4-7) in the glacial time and higher (7-8.4) in the interglacial time. Changes in soil pH allowed the evaluation of changes in soil CO2 based on the atmosphere-soil CO2 balance. The results imply that the lower winter MAAT variation with a lower winter atmospheric CO2 concentration might have resulted in a higher pH in the interglacial period. Our records provide a new insight into the evolution of atmospheric CO2 between glacial and interglacial cycles in East Asia. Key words: South China Sea, MBT/CBT, b-GDGTs, MAAT, pH

  13. Effect of Repeated Freeze-Thaw Cycles on Beef Quality and Safety

    Science.gov (United States)

    Rahman, Mohammad Hafizur; Hossain, Mohammad Mujaffar; Rahman, Syed Mohammad Ehsanur; Hashem, Mohammad Abul

    2014-01-01

    The objectives of this study were to know the effect of repeated freeze-thaw cycles of beef on the sensory, physicochemical quality and microbiological assessment. The effects of three successive freeze-thaw cycles on beef forelimb were investigated comparing with unfrozen fresh beef for 75 d by keeping at −20±1℃. The freeze-thaw cycles were subjected to three thawing methods and carried out to know the best one. As the number of freeze-thaw cycles increased color and odor declined significantly before cook within the cycles and tenderness, overall acceptability also declined among the cycles after cook by thawing methods. The thawing loss increased and dripping loss decreased significantly (pcycles and then decreased. Cooking loss increased in cycle 1 and 3, but decreased in cycle 2. pH decreased significantly (pcycles. Moreover, drip loss, cooking loss and WHC were affected (pcycles. 2-Thiobarbituric acid (TBARS) value increased (pcycles and among the cycles by thawing methods. Total viable bacteria, total coliform and total yeast-mould count decreased significantly (pcycles in comparison to the initial count in repeated freeze-thaw cycles. As a result, repeated freeze-thaw cycles affected the sensory, physicochemical and microbiological qua- lity of beef, causing the deterioration of beef quality, but improved the microbiological quality. Although repeated freeze-thaw cycles did not affect much on beef quality and safety but it may be concluded that repeated freeze and thaw should be minimized in terms of beef color for commercial value and WHC and tenderness/juiciness for eating quality. PMID:26761286

  14. Optimization of urinary dipstick pH: Are multiple dipstick pH readings reliably comparable to commercial 24-hour urinary pH?

    Science.gov (United States)

    Abbott, Joel E; Miller, Daniel L; Shi, William; Wenzler, David; Elkhoury, Fuad F; Patel, Nishant D; Sur, Roger L

    2017-09-01

    Accurate measurement of pH is necessary to guide medical management of nephrolithiasis. Urinary dipsticks offer a convenient method to measure pH, but prior studies have only assessed the accuracy of a single, spot dipstick. Given the known diurnal variation in pH, a single dipstick pH is unlikely to reflect the average daily urinary pH. Our goal was to determine whether multiple dipstick pH readings would be reliably comparable to pH from a 24-hour urine analysis. Kidney stone patients undergoing a 24-hour urine collection were enrolled and took images of dipsticks from their first 3 voids concurrently with the 24-hour collection. Images were sent to and read by a study investigator. The individual and mean pH from the dipsticks were compared to the 24-hour urine pH and considered to be accurate if the dipstick readings were within 0.5 of the 24-hour urine pH. The Bland-Altman test of agreement was used to further compare dipstick pH relative to 24-hour urine pH. Fifty-nine percent of patients had mean urinary pH values within 0.5 pH units of their 24-hour urine pH. Bland-Altman analysis showed a mean difference between dipstick pH and 24-hour urine pH of -0.22, with an upper limit of agreement of 1.02 (95% confidence interval [CI], 0.45-1.59) and a lower limit of agreement of -1.47 (95% CI, -2.04 to -0.90). We concluded that urinary dipstick based pH measurement lacks the precision required to guide medical management of nephrolithiasis and physicians should use 24-hour urine analysis to base their metabolic therapy.

  15. pH Triggered Recovery and Reuse of Thiolated Poly(acrylic acid) Functionalized Gold Nanoparticles with Applications in Colloidal Catalysis.

    Science.gov (United States)

    Ansar, Siyam M; Fellows, Benjamin; Mispireta, Patrick; Mefford, O Thompson; Kitchens, Christopher L

    2017-08-08

    Thiolated poly(acrylic acid) (PAA-SH) functionalized gold nanoparticles were explored as a colloidal catalyst with potential application as a recoverable catalyst where the PAA provides pH-responsive dispersibility and phase transfer capability between aqueous and organic media. This system demonstrates complete nanoparticle recovery and redispersion over multiple reaction cycles without changes in nanoparticle morphology or reduction in conversion. The catalytic activity (rate constant) was reduced in subsequent reactions when recovery by aggregation was employed, despite unobservable changes in morphology or dispersibility. When colloidal catalyst recovery employed a pH induced phase transfer between two immiscible solvents, the catalytic activity of the recovered nanoparticles was unchanged over four cycles, maintaining the original rate constant and 100% conversion. The ability to recover and reuse colloidal catalysts by aggregation/redispersion and phase transfer methods that occur at low and high pH, respectively, could be used for different gold nanoparticle catalyzed reactions that occur at different pH conditions.

  16. PhMYB4 fine-tunes the floral volatile signature of Petunia x hybrida through PhC4H.

    Science.gov (United States)

    Colquhoun, Thomas A; Kim, Joo Young; Wedde, Ashlyn E; Levin, Laura A; Schmitt, Kyle C; Schuurink, Robert C; Clark, David G

    2011-01-01

    In Petunia × hybrida cv 'Mitchell Diploid' (MD), floral volatile benzenoid/phenylpropanoid (FVBP) biosynthesis is controlled spatially, developmentally, and daily at molecular, metabolic, and biochemical levels. Multiple genes have been shown to encode proteins that either directly catalyse a biochemical reaction yielding FVBP compounds or are involved in metabolite flux prior to the formation of FVBP compounds. It was hypothesized that multiple transcription factors are involved in the precise regulation of all necessary genes, resulting in the specific volatile signature of MD flowers. After acquiring all available petunia transcript sequences with homology to Arabidopsis thaliana R2R3-MYB transcription factors, PhMYB4 (named for its close identity to AtMYB4) was identified, cloned, and characterized. PhMYB4 transcripts accumulate to relatively high levels in floral tissues at anthesis and throughout open flower stages, which coincides with the spatial and developmental distribution of FVBP production and emission. Upon RNAi suppression of PhMYB4 (ir-PhMYB4) both petunia cinnamate-4-hydroxylase (PhC4H1 and PhC4H2) gene transcript levels were significantly increased. In addition, ir-PhMYB4 plants emit higher levels of FVBP compounds derived from p-coumaric acid (isoeugenol and eugenol) compared with MD. Together, these results indicate that PhMYB4 functions in the repression of C4H transcription, indirectly controlling the balance of FVBP production in petunia floral tissue (i.e. fine-tunes).

  17. Financial Instability - a Result of Excess Liquidity or Credit Cycles?

    DEFF Research Database (Denmark)

    Heebøll-Christensen, Christian

    This paper compares the financial destabilizing effects of excess liquidity versus credit growth, in relation to house price bubbles and real economic booms. The analysis uses a cointegrated VAR model based on US data from 1987 to 2010, with a particulary focus on the period preceding the global...... financial crisis. Consistent with monetarist theory, the results suggest a stable money supply-demand relation in the period in question. However, the implied excess liquidity only resulted in financial destabilizing effect after year 2000. Meanwhile, the results also point to persistent cycles of real...... house prices and leverage, which appear to have been driven by real credit shocks, in accordance with post-Keynesian theories on financial instability. Importantly, however, these mechanisms of credit growth and excess liquidity are found to be closely related. In regards to the global financial crisis...

  18. Corrosion Effects on the Fatigue Crack Propagation of Giga-Grade Steel and its Heat Affected Zone in pH Buffer Solutions for Automotive Application

    Science.gov (United States)

    Lee, H. S.

    2018-03-01

    Corrosion fatigue crack propagation test was conducted of giga-grade steel and its heat affected zone in pH buffer solutions, and the results were compared with model predictions. Pure corrosion effect on fatigue crack propagation, particularly, in corrosive environment was evaluated by means of the modified Forman equation. As shown in results, the average corrosion rate determined from the ratio of pure corrosion induced crack length to entire crack length under a cycle load were 0.11 and 0.37 for base metal and heat affected zone, respectively, with load ratio of 0.5, frequency of 0.5 and pH 10.0 environment. These results demonstrate new interpretation methodology for corrosion fatigue crack propagation enabling the pure corrosion effects on the behavior to be determined.

  19. Comparative Evaluation of the Effect of Menstruation, Pregnancy and Menopause on Salivary Flow Rate, pH and Gustatory Function

    Science.gov (United States)

    Shetty, Vishwaprakash; Dave, Aparna; Arora, Manpreet; Hans, Vibha; Madan, Ajay

    2014-01-01

    Objective: There are five situations in a women’s life during which hormone fluctuations make them more susceptible to oral health problems – during puberty, at certain points in the monthly menstrual cycle, when using birth control pills, during pregnancy, and at menopause. The present study aimed at evaluating the effect of menstruation, pregnancy and menopause on salivary flow rate, pH and gustatory function. Materials and Methods: The study was carried out on 120 patients including 30 controls (with normal menstrual cycle of 28 to 30 d) and 90 cases (30 patients within three days of menstruation, 30 pregnant and 30 postmenopausal). Paraffin-stimulated saliva samples were obtained by expectoration to calculate salivary flow rate, pH was measured electrometically and patients were prospectively evaluated for gustatory function. Then, whole mouth taste test was performed in which the quality identification and intensity ratings of taste solutions were measured. Results: No statistically significant difference was found between the groups with respect to salivary flow rate but pH values were significantly lower in post menopausal women (pwomen than intensity of taste perception for other tastes (pwomen reported change in their dietary habits as all of them expressed liking for sweeter food. Conclusion: Reduced salivary flow rate and pH in postmen­opausal women may make them more prone to the occurrence of oral health problems. Also, pregnant and postmenopausal women appeared to have a reduced perception of sucrose, which can alter eating habits, such as intake of more sweet foods whereas no significant difference is observed in taste perception of NaCl, citric acid and quinine hydrochloride between the subjects. PMID:25478455

  20. Iridium Oxide-reduced Graphene Oxide Nanohybrid Thin Film Modified Screen-printed Electrodes as Disposable Electrochemical Paper Microfluidic pH Sensors.

    Science.gov (United States)

    Yang, Jiang; Kwak, Tae-Joon; Zhang, Xiaodong; McClain, Robert; Chang, Woo-Jin; Gunasekaran, Sundaram

    2016-11-22

    A facile, controllable, inexpensive and green electrochemical synthesis of IrO2-graphene nanohybrid thin films is developed to fabricate an easy-to-use integrated paper microfluidic electrochemical pH sensor for resource-limited settings. Taking advantages from both pH meters and strips, the pH sensing platform is composed of hydrophobic barrier-patterned paper micropad (µPAD) using polydimethylsiloxane (PDMS), screen-printed electrode (SPE) modified with IrO2-graphene films and molded acrylonitrile butadiene styrene (ABS) plastic holder. Repetitive cathodic potential cycling was employed for graphene oxide (GO) reduction which can completely remove electrochemically unstable oxygenated groups and generate a 2D defect-free homogeneous graphene thin film with excellent stability and electronic properties. A uniform and smooth IrO2 film in nanoscale grain size is anodically electrodeposited onto the graphene film, without any observable cracks. The resulting IrO2-RGO electrode showed slightly super-Nernstian responses from pH 2-12 in Britton-Robinson (B-R) buffers with good linearity, small hysteresis, low response time and reproducibility in different buffers, as well as low sensitivities to different interfering ionic species and dissolved oxygen. A simple portable digital pH meter is fabricated, whose signal is measured with a multimeter, using high input-impedance operational amplifier and consumer batteries. The pH values measured with the portable electrochemical paper-microfluidic pH sensors were consistent with those measured using a commercial laboratory pH meter with a glass electrode.

  1. The role of pCO2 in astronomically-paced climate and carbon cycle variations in the Middle Miocene

    Science.gov (United States)

    Penman, D. E.; Hull, P. M.; Scher, H.; Kirtland Turner, S.; Ridgwell, A.

    2017-12-01

    The pace of Earth's background climate variability is known to be driven by the Milankovitch cycles, variations in Earth's orbital parameters and axial tilt. While the Milankovitch (orbital) theory of climate change is very nearly universally accepted, the climate system mechanisms and feedbacks responsible for amplifying orbital cycles preserved in the geologic record remain uncertain. For the late Pleistocene, the ice core-derived record of atmospheric carbon dioxide (pCO2) is strongly coupled with global temperature on orbital time scales, indicating that internal feedbacks involving the carbon cycle amplify or even cause the large changes in global temperature during orbitally driven glacial-interglacial cycles. However, for earlier time periods beyond the range of ice cores (the last 800 kyr), it is not possible to directly compare records of pCO2 to orbital climate cycles because there are no high-resolution (orbitally resolved) records of pCO2 before the Pliocene. We address this deficiency with a high-resolution ( 5-10 kyr spacing) record of planktonic foraminiferal d11B-derived surface seawater pH (as well as d13C and trace metal analyses) over a 500 kyr time window in a sedimentary record with known Milankovitch-scale climate and carbon cycle oscillations: the Middle Miocene (14.0 - 14.5 Ma) at ODP Site 926 (subtropical North Atlantic). The resulting pH record can be used to constrain atmospheric pCO2, allowing comparison of the timescale and magnitude of carbon cycle changes during a period of eccentricity-dominated variability in the response of the global climate system (the Late Pleistocene) with a period of obliquity-dominance (the middle Miocene). These new records of planktic d11B and d13C will then be used to guide simulations of astronomical climate forcing in Earth System models, resulting in refined estimates of pCO2 changes over orbital cycles and providing quantitative constraints on the mechanisms and feedbacks responsible for the

  2. Correlation of transmissive fractures in holes OL-PH1, ONK-PH2 .. ONK-PH7 and ONKALO tunnel fractures

    International Nuclear Information System (INIS)

    Palmen, J; Nummela, J.; Ahokas, H.

    2011-02-01

    In a preceding study Posiva flow logging (PFL) with a 0.5 m test interval and 10 cm steps has been used together with optical drillhole images and core logging fracture data for the exact determination of the depth of hydraulically conductive fractures in pilot holes. The fracture traces has been mapped from the ONKALO tunnel walls as a part of the systematic mapping. The mapping results has been digitized to a 3D tunnel layout in Surpac Vision programme. The data integrity and fracture trace uniqueness has been verified by Datactica Oy and further collected to a database (Rakokanta D atactica P osiva20091119.mdb). Water leakage of the mapped fractures exists as an attribute field for each fracture, but the value of the attribute has not been assessed conclusively. Those fractures mapped with leakage attribute have been defined as flowing, dripping, wet, or damp where the attribute is recorded. The fractures with no leakage attribute value appear to be dry (not leaking) or the information is not available (assessment was not performed). The water leaking surfaces on ONKALO tunnel wall have been mapped sequentially and conclusively (twice a year) as a part of the Olkiluoto monitoring program (OMO) using an equal five step measure as used with fracture traces in systematic mapping. The PFL results correlated with core logging fracture data from pilot holes OL-PH1 and ONK-PH2 .. ONK-PH7 were in this work further correlated with the fractures mapped from the ONKALO tunnel walls. Each hydraulically conductive fracture of OL-PH1 and ONK-PH2 - ONK-PH7 was investigated and linked to ONKALO fracture of a coherent orientation and matching location, where such fracture trace was available. The main objective of the work was to identify the ONKALO fractures which correspond to the flow from fracture(s) identified with the PFL method in pilot holes and to collect basic information about the occurrence, frequency and orientation of water bearing fractures along ONKALO tunnel

  3. Influence of metallurgical phase transformation on crack propagation of 15-5PH stainless steel and 16MND5 low carbon steel

    International Nuclear Information System (INIS)

    Liu, J.

    2012-01-01

    This study focuses on the effects of phase transformations on crack propagation. We want to understand the changes of fracture toughness during welding. In this work, fracture toughness is expressed by J-integral. There are many experimental methods to obtain the critical toughness JIC but they are impractical for our investigation during phase transformation. That is the reason why we have proposed a method coupling mechanical tests, digital image correlation and finite element simulation. The fracture tests are implemented on pre-cracked single edge notched plate sample which is easy for machining and heat conduct during phase transformation. The tests are conducted at different temperatures until rupture. Digital image correlation gives us the displacement information on every sample. Each test is then simulated by finite element where the fracture toughness is evaluated by the method G-Theta at the crack propagation starting moment found by potential drop method and digital image correlation technical. Two materials have been studied, 15Cr-5Ni martensitic precipitation hardening stainless steel and 16MND5 ferritic low carbon steel. For these two materials, different test temperatures were chosen before, during and after phase transformation for testing and failure characterization of the mechanical behavior. Investigation result shows that metallurgical phase transformation has an influence on fracture toughness and further crack propagation. For 15-5PH, the result of J1C shows that the as received 15-5PH has higher fracture toughness than the one at 200 C. The toughness is also higher than the original material after one cycle heat treatment probably due to some residual austenite. Meanwhile, pure austenite 15-5PH at 200 C has higher fracture toughness than pure martensitic 15-5PH at 200 C. For 16MND5, the result also proves that the phase transformation affects fracture toughness. The as received material has bigger J1C than the situation where it was heated

  4. Development tendencies in cycle chemistry of fossil fired power plants

    Energy Technology Data Exchange (ETDEWEB)

    Daucik, K [Skaerbaekvaerket, Faelleskemikerne, Fredericia (Denmark)

    1996-12-01

    The development of cycle chemistry during the past 50 years is described and the main tendencies are pointed out. Improvement of cycle purity is the most dominant evolution, which introduces more freedom with respect to pH and redox potential control. Units with once-through boilers have profited most from this development. The development of boiler water chemistry in drum boilers also tends towards higher purity and less chemicals, which raises possibilities for oxygenated treatment. (au)

  5. Induction of Oxidative Stress and Antioxidative Mechanisms in Arabidopsis thaliana after Uranium Exposure at pH 7.5

    Directory of Open Access Journals (Sweden)

    Eline Saenen

    2015-06-01

    Full Text Available To evaluate the environmental impact of uranium (U contamination, it is important to investigate the effects of U at ecologically relevant conditions. Since U speciation, and hence its toxicity, strongly depends on environmental pH, the present study aimed to investigate dose-dependent effects of U at pH 7.5. Arabidopsis thaliana plants (Mouse-ear Cress were exposed for three days to different U concentrations at pH 7.5. In the roots, the increased capacities of ascorbate peroxidase and glutathione reductase indicate an important role for the ascorbate-glutathione cycle during U-induced stress. However, a significant decrease in the ascorbate redox state was observed after exposure to 75 and 100 µM U, indicating that those roots are severely stressed. In accordance with the roots, the ascorbate-glutathione cycle plays an important role in the antioxidative defence systems in A. thaliana leaves exposed to U at pH 7.5 as the ascorbate and glutathione biosynthesis were upregulated. In addition, small inductions of enzymes of the antioxidative defence system were observed at lower U concentrations to counteract the U-induced stress. However, at higher U concentrations it seems that the antioxidative defence system of the leaves collapses as reductions in enzyme activities and gene expression levels were observed.

  6. Attenuation and diel cycling of coal-mine drainage constituents in a passive treatment wetland: A case study from Lambert Run, West Virginia, USA

    International Nuclear Information System (INIS)

    Vesper, Dorothy J.; Smilley, Michael J.

    2010-01-01

    This study reports changes in coal-mine drainage constituent concentrations through a passive treatment wetland and over diel cycles. The purpose of the study was to determine what physiochemical mechanisms control attenuation of metals and if they varied by location and through time. The source water was slightly acidic (average pH 5.43); downstream degassing of CO 2 contributed to an increase in pH prior to discharge from the site (average pH 7.05). Aluminum, Fe, rare earth elements (REE) and Y were removed to a greater extent than were Mn, Co and Ni. At acidic pH, the REE and Y were generally complexed by SO 4 . At higher pH, carbonate complexes became more important. The REE and Y concentrations were normalized to the North American Shale Composite standard; the normalized patterns were coherent near the source but anomalies of Ce and Y were present further downstream indicating oxidation and sorption processes. Four sets of diel-based samples were collected, one from a shallow, surface-flow wetland and three from a deeper, newly constructed wetland. Well-defined diel cycles were observed for concentrations of Si, Mn, Fe, Co, Ni, As, REE and Y in the shallow wetland. In all cases, the concentrations increased (up to 863%) during night and decreased during the day. These cycles had an inverse relationship with the temperature cycle (pH had no discernable cycle). The consistency of concentration cycles suggests a common mechanism, most likely associated with the formation of Fe oxyhydroxides. The increased rate of Fe 2+ oxidation in warm water can account for the cycles in Fe; scavenging of the other elements by the Fe precipitate can account for the consistency of the cycles even though the elements include cations, anions (H 2 AsO 4 - or HAsO 4 -2 ), and neutral species (H 4 SiO 4 0 ). While REE and Y had clear cycles in the constructed wetland, the other elements did not. This is partially due to the lower elemental concentrations (including Fe) but the cycles

  7. Flocculation of Chlamydomonas reinhardtii with Different Phenotypic Traits by Metal Cations and High pH

    Directory of Open Access Journals (Sweden)

    Jianhua Fan

    2017-11-01

    Full Text Available Concentrating algal cells by flocculation as a prelude to centrifugation could significantly reduce the energy and cost of harvesting the algae. However, how variation in phenotypic traits such as cell surface features, cell size and motility alter the efficiency of metal cation and pH-induced flocculation is not well understood. Our results demonstrate that both wild-type and cell wall-deficient strains of the green unicellular alga Chlamydomonas reinhardtii efficiently flocculate (>90% at an elevated pH of the medium (pH 11 upon the addition of divalent cations such as calcium and magnesium (>5 mM. The trivalent ferric cation (at 10 mM proved to be essential for promoting flocculation under weak alkaline conditions (pH ∼8.5, with a maximum efficiency that exceeded 95 and 85% for wild-type CC1690 and the cell wall-deficient sta6 mutant, respectively. Near complete flocculation could be achieved using a combination of 5 mM calcium and a pH >11, while the medium recovered following cell removal could be re-cycled without affecting algal growth rates. Moreover, the absence of starch in the cell had little overall impact on flocculation efficiency. These findings contribute to our understanding of flocculation in different Chlamydomonas strains and have implications with respect to inexpensive methods for harvesting algae with different phenotypic traits. Additional research on the conditions (e.g., pH and metal ions used for efficient flocculation of diverse algal groups with diverse characteristics, at both small and large scale, will help establish inexpensive procedures for harvesting cell biomass.

  8. Development of Hybrid pH sensor for long-term seawater pH monitoring.

    Science.gov (United States)

    Nakano, Y.; Egashira, T.; Miwa, T.; Kimoto, H.

    2016-02-01

    We have been developing the in situ pH sensor (Hybrid pH sensor: HpHS) for the long-term seawater pH monitoring. We are planning to provide the HpHS for researchers and environmental consultants for observation of the CCS (Carbon dioxide Capture and Storage) monitoring system, the coastal environment monitoring system (e.g. Blue Carbon) and ocean acidification. The HpHS has two types of pH sensors (i.e. potentiometric pH sensor and spectrophotometric pH sensor). The spectrophotometric pH sensor can measure pH correctly and stably, however it needs large power consumption and a lot of reagents in a long period of observation. The pH sensor used m-cresol purple (mCP) as an indicator of pH (Clayton and Byrne, 1993 and Liu et al., 2011). We can choose both coefficients before deployment. On the other hand, although the potentiometric pH sensor is low power consumption and high-speed response (within 10 seconds), drifts in the pH of the potentiometric measurements may possibly occur for a long-term observation. The HpHS can measure in situ pH correctly and stably combining advantage of both pH sensors. The HpHS consists of an aluminum pressure housing with optical cell (main unit) and an aluminum silicon-oil filled, pressure-compensated vessel containing pumps and valves (diaphragm pump and valve unit) and pressure-compensated reagents bags (pH indicator, pure water and Tris buffer or certified reference material: CRM) with an ability to resist water pressure to 3000m depth. The main unit holds system control boards, pump drivers, data storage (micro SD card), LED right source, photodiode, optical cell and pressure proof windows. The HpHS also has an aluminum pressure housing that holds a rechargeable lithium-ion battery or a lithium battery for the power supply (DC 24 V). The HpHS is correcting the value of the potentiometric pH sensor (measuring frequently) by the value of the spectrophotometric pH sensor (measuring less frequently). It is possible to calibrate in

  9. Radiocaesium uptake and cycling in willow short rotation coppice

    International Nuclear Information System (INIS)

    Gommers, A.

    2002-01-01

    The document is an abstract of a PhD thesis. The study investigates the uptake and cycling of radiocaesium in willow short rotation coppice. Different factors influencing the soil-to-wood transfer of radiocaesium were investigated, among others the type of minerals, supply of potassium and soil composition

  10. Development of oxygen and pH sensors for aqueous systems

    International Nuclear Information System (INIS)

    Stvartak, C.; Alcock, C.B.; Li, B.; Wang, L.; Fergus, J.W.; Bakshi, N.

    1994-04-01

    Corrosion science has long recognized that two of the most important parameters in characterizing the corrosivity of an aqueous environment are oxygen chemical potential and pH. These parameters not only determine the thermodynamic driving forces for various corrosion reactions, but also characterize the rates of these reactions and hence the lifetime of a particular component. The primary goal of this project is to develop an electrochemical oxygen and pH sensor for continuous use in the cycle chemistry control of power plants. In the past year, electrochemical sensors with a metal/metal oxide or metal/metal hydride internal reference electrode and a fluoride-based electrolyte tube have been developed and tested in this laboratory. The corrosion tests showed that the LaF 3 -based solid electrolyte was very stable both chemically and physically in water. Furthermore, its electrical conductivity is 4 to 5 orders of magnitude higher than that of stabilized zirconia below 573 K (300 degree C), which is the main advantage of a fluoride-based electrolyte at low temperatures. With this electrolyte and the selected internal oxygen reference electrode (Ag/Ag 2 O), the electrochemical probe demonstrated Nernstian responses to the oxygen chemical potential and pH of the aqueous solution with good reproducibility. A similar cell with Zr/ZrH 1+x as the internal hydrogen reference electrode showed promising pH sensing characteristics. It is proposed that these two cells be combined to form a double-headed electrochemical probe to determine oxygen chemical potential and pH in the solution simultaneously

  11. Chemical Engineering Education in a Bologna Three Cycle Degree System

    DEFF Research Database (Denmark)

    Gani, Rafiqul

    For the purpose of harmonization of European higher education, Europe’s education system has been going through major changes under what is commonly known as the ”Bologna Process”. The Bologna declaration in 1999 was the start of the introduction of a three cycle degree system in higher education...... in Europe. To date, many European universities have adopted this degree structure. The Working Party on Education (WPE) of the European Federation of Chemical Engineering (EFCE) carried out research to determine the contents of higher education in chemical engineering (ChE) and related disciplines...... such as applied chemistry and process engineering throughout Europe. The result has been a set of recommendations for the first (BS), second (MS) and third (PhD) cycle chemical engineering education aligned to the Bologna Process. They recommend that students studying towards bachelor and masters qualifications...

  12. Modelling the Krebs cycle and oxidative phosphorylation.

    Science.gov (United States)

    Korla, Kalyani; Mitra, Chanchal K

    2014-01-01

    The Krebs cycle and oxidative phosphorylation are the two most important sets of reactions in a eukaryotic cell that meet the major part of the total energy demands of a cell. In this paper, we present a computer simulation of the coupled reactions using open source tools for simulation. We also show that it is possible to model the Krebs cycle with a simple black box with a few inputs and outputs. However, the kinetics of the internal processes has been modelled using numerical tools. We also show that the Krebs cycle and oxidative phosphorylation together can be combined in a similar fashion - a black box with a few inputs and outputs. The Octave script is flexible and customisable for any chosen set-up for this model. In several cases, we had no explicit idea of the underlying reaction mechanism and the rate determining steps involved, and we have used the stoichiometric equations that can be easily changed as and when more detailed information is obtained. The script includes the feedback regulation of the various enzymes of the Krebs cycle. For the electron transport chain, the pH gradient across the membrane is an essential regulator of the kinetics and this has been modelled empirically but fully consistent with experimental results. The initial conditions can be very easily changed and the simulation is potentially very useful in a number of cases of clinical importance.

  13. Micro Electrochemical pH Sensor Applicable for Real-Time Ratiometric Monitoring of pH Values in Rat Brains.

    Science.gov (United States)

    Zhou, Jie; Zhang, Limin; Tian, Yang

    2016-02-16

    To develop in vivo monitoring meter for pH measurements is still the bottleneck for understanding the role of pH plays in the brain diseases. In this work, a selective and sensitive electrochemical pH meter was developed for real-time ratiometric monitoring of pH in different regions of rat brains upon ischemia. First, 1,2-naphthoquinone (1,2-NQ) was employed and optimized as a selective pH recognition element to establish a 2H(+)/2e(-) approach over a wide range of pH from 5.8 to 8.0. The pH meter demonstrated remarkable selectivity toward pH detection against metal ions, amino acids, reactive oxygen species, and other biological species in the brain. Meanwhile, an inner reference, 6-(ferrocenyl)hexanethiol (FcHT), was selected as a built-in correction to avoid the environmental effect through coimmobilization with 1,2-NQ. In addition, three-dimensional gold nanoleaves were electrodeposited onto the electrode surface to amplify the signal by ∼4.0-fold and the measurement was achieved down to 0.07 pH. Finally, combined with the microelectrode technique, the microelectrochemical pH meter was directly implanted into brain regions including the striatum, hippocampus, and cortex and successfully applied in real-time monitoring of pH values in these regions of brain followed by global cerebral ischemia. The results demonstrated that pH values were estimated to 7.21 ± 0.05, 7.13 ± 0.09, and 7.27 ± 0.06 in the striatum, hippocampus, and cortex in the rat brains, respectively, in normal conditions. However, pH decreased to 6.75 ± 0.07 and 6.52 ± 0.03 in the striatum and hippocampus, upon global cerebral ischemia, while a negligible pH change was obtained in the cortex.

  14. Post-irradiation characterization of PH13-8Mo martensitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Jong, M.; Schmalz, F.; Rensman, J.W. [Nuclear Research and consultancy Group, Westerduinweg 3, 1755 ZG Petten (Netherlands); Luzginova, N.V., E-mail: luzginova@nrg.eu [Nuclear Research and consultancy Group, Westerduinweg 3, 1755 ZG Petten (Netherlands); Wouters, O.; Hegeman, J.B.J.; Laan, J.G. van der [Nuclear Research and consultancy Group, Westerduinweg 3, 1755 ZG Petten (Netherlands)

    2011-10-01

    The irradiation response of PH13-8Mo stainless steel was measured up to 2.5 dpa at 200 and 300 deg. C irradiation temperatures. The PH13-8Mo, a martensitic precipitation-hardened steel, was produced by Hot Isostatic Pressing at 1030 deg. C. The fatigue tests (high cycle fatigue and fatigue crack propagation) showed a test temperature dependency but no irradiation effects. Tensile tests showed irradiation hardening (yield stress increase) of approximately 37% for 200 deg. C irradiated material tested at 60 deg. C and approximately 32% for 300 deg. C irradiated material tested at 60 deg. C. This contradicts the shift in reference temperature (T{sub 0}) measured in toughness tests (Master Curve approach), where the {Delta}T{sub 0} for 300 deg. C irradiated is approximately 170 deg. C and the {Delta}T{sub 0} for the 200 deg. C irradiated is approximately 160 deg. C. This means that the irradiation hardening of PH13-8Mo steel is not suitable to predict the shift in the reference temperature for the Master Curve approach.

  15. Effect of pH value on particle morphology and electrochemical properties of LiFePO4 by hydrothermal method

    International Nuclear Information System (INIS)

    Song, Qingzhu; Ou, Xiuqin; Wang, Li; Liang, Guangchuan; Wang, Zuorui

    2011-01-01

    Graphical abstract: The pH value of system is adjusted in the range of 2.5-8.8 by using dilute sulfuric acid and ammonia water. The results indicated that the particle exhibits acute angle diamond flake-like morphology at pH = 2.5. With increase of pH value, the particle gradually becomes to round flake-like and irregular flake-like morphology. The optimal sample synthesized at pH = 6.4 exhibits discharge capacities of 151.8 mAh g -1 at 0.2 C rate and 129.3 mAh g -1 at 3 C rate. Highlights: → The pH value of solution affects greatly on particle morphology. → The solubility product determined the transition of interphases. → The disorder of atoms in crystal is affected by pH value. → LiFePO 4 with high capacity could be synthesized at slight acid or neutral conditions. -- Abstract: Lithium iron phosphate was prepared by hydrothermal synthesis using LiOH.H 2 O, FeSO 4 .7H 2 O and H 3 PO 4 as raw materials. The effects of pH value of reaction solution on particle morphology and electrochemical property were investigated. The pH value of the reaction solution was adjusted in the range of 2.5-8.8 by dilute sulfuric acid and ammonia water. The samples were characterized by field-emission scanning electronic microscope (FE-SEM), X-ray powder diffraction (XRD), constant-current charge/discharge cycling tests and chemical analysis. The results indicated that the particles exhibited acute angle diamond flake-like morphology at pH = 2.5, and as the pH value increased, the particle became hexagon flake-like, round flake-like and irregular flake-like morphology gradually. The optimal sample synthesized at pH = 6.4 exhibited discharge capacities of 151.8 mAh g -1 at 0.2 C rate and 129.3 mAh g -1 at 3 C rate. It was found that pH value affected the morphologies and properties of the product by means of different crystal growth rates.

  16. Amperometric micro pH measurements in oxygenated saliva.

    Science.gov (United States)

    Chaisiwamongkhol, Korbua; Batchelor-McAuley, Christopher; Compton, Richard G

    2017-07-24

    An amperometric micro pH sensor has been developed based on the chemical oxidation of carbon fibre surfaces (diameter of 9 μm and length of ca. 1 mm) to enhance the population of surface quinone groups for the measurement of salivary pH. The pH analysis utilises the electrochemically reversible two-electron, two-proton behaviour of surface quinone groups on the micro-wire electrodes. A Nernstian response is observed across the pH range 2-8 which is the pH range of many biological fluids. We highlight the measurement of pH in small volumes of biological fluids without the need for oxygen removal and specifically the micro pH electrode is examined by measuring the pH of commercial synthetic saliva and authentic human saliva samples. The results correspond well with those obtained by using commercial glass pH electrodes on large volume samples.

  17. pH Mapping on Tooth Surfaces for Quantitative Caries Diagnosis Using Micro Ir/IrOx pH Sensor.

    Science.gov (United States)

    Ratanaporncharoen, Chindanai; Tabata, Miyuki; Kitasako, Yuichi; Ikeda, Masaomi; Goda, Tatsuro; Matsumoto, Akira; Tagami, Junji; Miyahara, Yuji

    2018-04-03

    A quantitative diagnostic method for dental caries would improve oral health, which directly affects the quality of life. Here we describe the preparation and application of Ir/IrOx pH sensors, which are used to measure the surface pH of dental caries. The pH level is used as an indicator to distinguish between active and arrested caries. After a dentist visually inspected and defined 18 extracted dentinal caries at various positions as active or arrested caries, the surface pH values of sound and caries areas were directly measured with an Ir/IrOx pH sensor with a diameter of 300 μm as a dental explorer. The average pH values of the sound root, the arrested caries, and active caries were 6.85, 6.07, and 5.30, respectively. The pH obtained with an Ir/IrOx sensor was highly correlated with the inspection results by the dentist, indicating that the types of caries were successfully categorized. This caries testing technique using a micro Ir/IrOx pH sensor provides an accurate quantitative caries evaluation and has potential in clinical diagnosis.

  18. Deep-Sea DuraFET: A Pressure Tolerant pH Sensor Designed for Global Sensor Networks.

    Science.gov (United States)

    Johnson, Kenneth S; Jannasch, Hans W; Coletti, Luke J; Elrod, Virginia A; Martz, Todd R; Takeshita, Yuichiro; Carlson, Robert J; Connery, James G

    2016-03-15

    Increasing atmospheric carbon dioxide is driving a long-term decrease in ocean pH which is superimposed on daily to seasonal variability. These changes impact ecosystem processes, and they serve as a record of ecosystem metabolism. However, the temporal variability in pH is observed at only a few locations in the ocean because a ship is required to support pH observations of sufficient precision and accuracy. This paper describes a pressure tolerant Ion Sensitive Field Effect Transistor pH sensor that is based on the Honeywell Durafet ISFET die. When combined with a AgCl pseudoreference sensor that is immersed directly in seawater, the system is capable of operating for years at a time on platforms that cycle from depths of several km to the surface. The paper also describes the calibration scheme developed to allow calibrated pH measurements to be derived from the activity of HCl reported by the sensor system over the range of ocean pressure and temperature. Deployments on vertical profiling platforms enable self-calibration in deep waters where pH values are stable. Measurements with the sensor indicate that it is capable of reporting pH with an accuracy of 0.01 or better on the total proton scale and a precision over multiyear periods of 0.005. This system enables a global ocean observing system for ocean pH.

  19. Characterization of pH dependent Mn(II) oxidation strategies and formation of a bixbyite-like phase by Mesorhizobium australicum T-G1

    Science.gov (United States)

    Bohu, Tsing; Santelli, Cara M; Akob, Denise M.; Neu, Thomas R; Ciobota, Valerian; Rösch, Petra; Popp, Jürgen; Nietzsche, Sándor; Küsel, Kirsten

    2015-01-01

    Despite the ubiquity of Mn oxides in natural environments, there are only a few observations of biological Mn(II) oxidation at pH MOB) isolates limits our understanding of how pH influences biological Mn(II) oxidation in extreme environments. Here, we report that a novel MOB isolate, Mesorhizobium australicum strain T-G1, isolated from an acidic and metalliferous uranium mining area, can oxidize Mn(II) at both acidic and neutral pH using different enzymatic pathways. X-ray diffraction, Raman spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy revealed that T-G1 initiated bixbyite-like Mn oxide formation at pH 5.5 which coincided with multi-copper oxidase expression from early exponential phase to late stationary phase. In contrast, reactive oxygen species (ROS), particularly superoxide, appeared to be more important for T-G1 mediated Mn(II) oxidation at neutral pH. ROS was produced in parallel with the occurrence of Mn(II) oxidation at pH 7.2 from early stationary phase. Solid phase Mn oxides did not precipitate, which is consistent with the presence of a high amount of H2O2 and lower activity of catalase in the liquid culture at pH 7.2. Our results show that M. australicum T-G1, an acid tolerant MOB, can initiate Mn(II) oxidation by varying its oxidation mechanisms depending on the pH and may play an important role in low pH manganese biogeochemical cycling.

  20. Redox cycles of vitamin E: Hydrolysis and ascorbic acid dependent reduction of 8a-(alkyldioxy)tocopherones

    International Nuclear Information System (INIS)

    Liebler, D.C.; Kaysen, K.L.; Kennedy, T.A.

    1989-01-01

    Oxidation of the biological antioxidant α-tocopherol (vitamin E; TH) by peroxyl radicals yields 8a-(alkyldioxy)tocopherones, which either may hydrolyze to α-tocopheryl quinone (TQ) or may be reduced by ascorbic acid to regenerate TH. To define the chemistry of this putative two-electron TH redox cycle, we studied the hydrolysis and reduction of 8a-[(2,4-dimethyl-1-nitrilopent-2-yl)dioxyl]tocopherone (1) in acetonitrile/buffer mixtures and in phospholipid liposomes. TQ formation in acetonitrile/buffer mixtures, which was monitored spectrophotometrically, declined with increasing pH and could not be detected above pH 4. The rate of TQ formation from 1 first increased with time and then decreased in a first-order terminal phase. Rearrangement of 8a-hydroxy-α-tocopherone (2) to TQ displayed first-order kinetics identical with the terminal phase for TQ formation from 1. Both rate constants increased with decreasing pH. Hydrolysis of 1 in acetonitrile/H 2 18 O yielded [ 18 O]TQ. These observations suggest that 1 loses the 8a-(alkyldioxy) moiety to produce the tocopherone cation (T + ), which hydrolyzes to 2, the TQ-forming intermediate. Incubation of either 1 or 2 with ascorbic acid in acetonitrile/buffer yielded TH. Reduction of both 1 and 2 decreased with increasing pH. In phosphatidylcholine liposomes at pH 7, approximately 10% of the T + generated from 1 was reduced to TH by 5 mM ascorbic acid. The results collectively demonstrate that T + is the ascorbic acid reducible intermediate in a two-electron TH redox cycle, a process that probably would require biocatalysis to proceed in biological membranes

  1. Real-time control of oxic phase using pH (mV)-time profile in swine wastewater treatment

    International Nuclear Information System (INIS)

    Ga, C.H.; Ra, C.S.

    2009-01-01

    The feasibility of real-time control of the oxic phase using the pH (mV)-time profile in a sequencing batch reactor for swine wastewater treatment was evaluated, and the characteristics of the novel real-time control strategies were analyzed in two different concentrated wastewaters. The nitrogen break point (NBP) on the moving slope change (MSC) of the pH (mV) was designated as a real-time control point, and a pilot-scale sequencing batch reactor (18 m 3 ) was designed to fulfill the objectives of the study. Successful real-time control using the developed control strategy was achieved despite the large variations in the influent strength and the loading rate per cycle. Indeed, complete and consistent removal of NH 4 -N (100% removal) was achieved. There was a strong positive correlation (r 2 = 0.9789) between the loading rate and soluble total organic carbon (TOCs) removal, and a loading rate of 100 g/m 3 /cycle was found to be optimum for TOCs removal. Experimental data showed that the real-time control strategy using the MSC of the pH (mV)-time profile could be utilized successfully for the removal of nitrogen from swine wastewater. Furthermore, the pH (mV) was a more reliable real-time control parameter than the oxidation-reduction potential (ORP) for the control of the oxic phase. However, the nitrate knee point (NKP) appeared more consistently upon the completion of denitrification on the ORP-time profile than on the pH (mV)-time profile.

  2. A pH-Regulated Quality Control Cycle for Surveillance of Secretory Protein Assembly

    Science.gov (United States)

    Vavassori, Stefano; Cortini, Margherita; Masui, Shoji; Sannino, Sara; Anelli, Tiziana; Caserta, Imma R.; Fagioli, Claudio; Mossuto, Maria F.; Fornili, Arianna; van Anken, Eelco; Degano, Massimo; Inaba, Kenji; Sitia, Roberto

    2013-01-01

    Summary To warrant the quality of the secretory proteome, stringent control systems operate at the endoplasmic reticulum (ER)-Golgi interface, preventing the release of nonnative products. Incompletely assembled oligomeric proteins that are deemed correctly folded must rely on additional quality control mechanisms dedicated to proper assembly. Here we unveil how ERp44 cycles between cisGolgi and ER in a pH-regulated manner, patrolling assembly of disulfide-linked oligomers such as IgM and adiponectin. At neutral, ER-equivalent pH, the ERp44 carboxy-terminal tail occludes the substrate-binding site. At the lower pH of the cisGolgi, conformational rearrangements of this peptide, likely involving protonation of ERp44’s active cysteine, simultaneously unmask the substrate binding site and −RDEL motif, allowing capture of orphan secretory protein subunits and ER retrieval via KDEL receptors. The ERp44 assembly control cycle couples secretion fidelity and efficiency downstream of the calnexin/calreticulin and BiP-dependent quality control cycles. PMID:23685074

  3. The effect of pH on chronic aquatic nickel toxicity is dependent on the pH itself: Extending the chronic nickel bioavailability models.

    Science.gov (United States)

    Nys, Charlotte; Janssen, Colin R; Van Sprang, Patrick; De Schamphelaere, Karel A C

    2016-05-01

    The environmental quality standard for Ni in the European Commission's Water Framework Directive is bioavailability based. Although some of the available chronic Ni bioavailability models are validated only for pH ≤ 8.2, a considerable fraction of European surface waters has a pH > 8.2. Therefore, the authors investigated the effect of a change in pH from 8.2 to 8.7 on chronic Ni toxicity in 3 invertebrate (Daphnia magna, Lymnaea stagnalis, and Brachionus calyciflorus) and 2 plant species (Pseudokirchneriella subcapitata and Lemna minor). Nickel toxicity was almost always significantly higher at pH 8.7 than at pH 8.2. To test whether the existing chronic Ni bioavailability models developed for pH ≤ 8.2 can be used at higher pH levels, Ni toxicity at pH 8.7 was predicted based on Ni toxicity observed at pH 8.2. This resulted in a consistent underestimation of toxicity. The results suggest that the effect of pH on Ni(2+) toxicity is dependent on the pH itself: the slope of the pH effect is steeper above than below pH 8.2 for species for which a species-specific bioavailability model exists. Therefore, the existing chronic Ni bioavailability models were modified to allow predictions of chronic Ni toxicity to invertebrates and plants in the pH range of 8.2 to 8.7 by applying a pH slope (SpH ) dependent on the pH of the target water. These modified Ni bioavailability models resulted in more accurate predictions of Ni toxicity to all 5 species (within 2-fold error), without the bias observed using the bioavailability models developed for pH ≤ 8.2. The results of the present study can decrease the uncertainty in implementing the bioavailability-based environmental quality standard under the Water Framework Directive for high-pH regions in Europe. © 2015 SETAC.

  4. Salivary pH: A diagnostic biomarker.

    Science.gov (United States)

    Baliga, Sharmila; Muglikar, Sangeeta; Kale, Rahul

    2013-07-01

    Saliva contains a variety of host defense factors. It influences calculus formation and periodontal disease. Different studies have been done to find exact correlation of salivary biomarkers with periodontal disease. With a multitude of biomarkers and complexities in their determination, the salivary pH may be tried to be used as a quick chairside test. The aim of this study was to analyze the pH of saliva and determine its relevance to the severity of periodontal disease. The study population consisted of 300 patients. They were divided into three groups of 100 patients each: Group A had clinically healthy gingiva, Group B who had generalized chronic gingivitis and Group C who had generalized chronic periodontitis. The randomized unstimulated saliva from each patient was collected and pH was tested. Data was analyzed statistically using analysis of variance technique. The salivary pH was more alkaline for patients with generalized chronic gingivitis as compared with the control group (P = 0.001) whereas patients with generalized chronic periodontitis had more acidic pH as compared with the control group (P = 0.001). These results indicate a significant change in the pH depending on the severity of the periodontal condition. The salivary pH shows significant changes and thus relevance to the severity of periodontal disease. Salivary pH may thus be used as a quick chairside diagnostic biomarker.

  5. Glacial--interglacial stability of ocean pH inferred from foraminifer dissolution rates.

    Science.gov (United States)

    Anderson, David M; Archer, David

    2002-03-07

    The pH of the ocean is controlled by the chemistry of calcium carbonate. This system in turn plays a large role in regulating the CO2 concentration of the atmosphere on timescales of thousands of years and longer. Reconstructions of ocean pH and carbonate-ion concentration are therefore needed to understand the ocean's role in the global carbon cycle. During the Last Glacial Maximum (LGM), the pH of the whole ocean is thought to have been significantly more basic, as inferred from the isotopic composition of boron incorporated into calcium carbonate shells, which would partially explain the lower atmospheric CO2 concentration at that time. Here we reconstruct carbonate-ion concentration--and hence pH--of the glacial oceans, using the extent of calcium carbonate dissolution observed in foraminifer faunal assemblages as compiled in the extensive global CLIMAP data set. We observe decreased carbonate-ion concentrations in the glacial Atlantic Ocean, by roughly 20 micromolkg-1, while little change occurred in the Indian and Pacific oceans relative to today. In the Pacific Ocean, a small (5 micromolkg-1) increase occurred below 3,000m. This rearrangement of ocean pH may be due to changing ocean circulation from glacial to present times, but overall we see no evidence for a shift in the whole-ocean pH as previously inferred from boron isotopes.

  6. Improving ethanol productivity through self-cycling fermentation of yeast: a proof of concept.

    Science.gov (United States)

    Wang, Jie; Chae, Michael; Sauvageau, Dominic; Bressler, David C

    2017-01-01

    The cellulosic ethanol industry has developed efficient strategies for converting sugars obtained from various cellulosic feedstocks to bioethanol. However, any further major improvements in ethanol productivity will require development of novel and innovative fermentation strategies that enhance incumbent technologies in a cost-effective manner. The present study investigates the feasibility of applying self-cycling fermentation (SCF) to cellulosic ethanol production to elevate productivity. SCF is a semi-continuous cycling process that employs the following strategy: once the onset of stationary phase is detected, half of the broth volume is automatically harvested and replaced with fresh medium to initiate the next cycle. SCF has been shown to increase product yield and/or productivity in many types of microbial cultivation. To test whether this cycling process could increase productivity during ethanol fermentations, we mimicked the process by manually cycling the fermentation for five cycles in shake flasks, and then compared the results to batch operation. Mimicking SCF for five cycles resulted in regular patterns with regards to glucose consumption, ethanol titer, pH, and biomass production. Compared to batch fermentation, our cycling strategy displayed improved ethanol volumetric productivity (the titer of ethanol produced in a given cycle per corresponding cycle time) and specific productivity (the amount of ethanol produced per cellular biomass) by 43.1 ± 11.6 and 42.7 ± 9.8%, respectively. Five successive cycles contributed to an improvement of overall productivity (the aggregate amount of ethanol produced at the end of a given cycle per total processing time) and the estimated annual ethanol productivity (the amount of ethanol produced per year) by 64.4 ± 3.3 and 33.1 ± 7.2%, respectively. This study provides proof of concept that applying SCF to ethanol production could significantly increase productivities, which will help strengthen the

  7. Compartment-specific pH monitoring in Bacillus subtilis using fluorescent sensor proteins: a tool to analyze the antibacterial effect of weak organic acids.

    NARCIS (Netherlands)

    van Beilen, J.W.A.; Brul, S.

    2013-01-01

    The internal pH (pHi) of a living cell is one of its most important physiological parameters. To monitor the pH inside Bacillus subtilis during various stages of its life cycle, we constructed an improved version (IpHluorin) of the ratiometric, pH-sensitive fluorescent protein pHluorin by extending

  8. Characterization of pH dependent Mn(II) oxidation strategies and formation of a bixbyite-like phase by Mesorhizobium australicum T-G1

    Science.gov (United States)

    Bohu, Tsing; Santelli, Cara M; Akob, Denise M.; Neu, Thomas R; Ciobota, Valerian; Rösch, Petra; Popp, Jürgen; Nietzsche, Sándor; Küsel, Kirsten

    2015-01-01

    Despite the ubiquity of Mn oxides in natural environments, there are only a few observations of biological Mn(II) oxidation at pH < 6. The lack of low pH Mn-oxidizing bacteria (MOB) isolates limits our understanding of how pH influences biological Mn(II) oxidation in extreme environments. Here, we report that a novel MOB isolate, Mesorhizobium australicum strain T-G1, isolated from an acidic and metalliferous uranium mining area, can oxidize Mn(II) at both acidic and neutral pH using different enzymatic pathways. X-ray diffraction, Raman spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy revealed that T-G1 initiated bixbyite-like Mn oxide formation at pH 5.5 which coincided with multi-copper oxidase expression from early exponential phase to late stationary phase. In contrast, reactive oxygen species (ROS), particularly superoxide, appeared to be more important for T-G1 mediated Mn(II) oxidation at neutral pH. ROS was produced in parallel with the occurrence of Mn(II) oxidation at pH 7.2 from early stationary phase. Solid phase Mn oxides did not precipitate, which is consistent with the presence of a high amount of H2O2 and lower activity of catalase in the liquid culture at pH 7.2. Our results show that M. australicum T-G1, an acid tolerant MOB, can initiate Mn(II) oxidation by varying its oxidation mechanisms depending on the pH and may play an important role in low pH manganese biogeochemical cycling.

  9. Mechanisms of intragastric pH sensing.

    Science.gov (United States)

    Goo, Tyralee; Akiba, Yasutada; Kaunitz, Jonathan D

    2010-12-01

    Luminal amino acids and lack of luminal acidity as a result of acid neutralization by intragastric foodstuffs are powerful signals for acid secretion. Although the hormonal and neural pathways underlying this regulatory mechanism are well understood, the nature of the gastric luminal pH sensor has been enigmatic. In clinical studies, high pH, tryptic peptides, and luminal divalent metals (Ca(2+) and Mg(2+)) increase gastrin release and acid production. The calcium-sensing receptor (CaSR), first described in the parathyroid gland but expressed on gastric G cells, is a logical candidate for the gastric acid sensor. Because CaSR ligands include amino acids and divalent metals, and because extracellular pH affects ligand binding in the pH range of the gastric content, its pH, metal, and nutrient-sensing functions are consistent with physiologic observations. The CaSR is thus an attractive candidate for the gastric luminal sensor that is part of the neuroendocrine negative regulatory loop for acid secretion.

  10. The Semen pH Affects Sperm Motility and Capacitation.

    Science.gov (United States)

    Zhou, Ji; Chen, Li; Li, Jie; Li, Hongjun; Hong, Zhiwei; Xie, Min; Chen, Shengrong; Yao, Bing

    2015-01-01

    As the chemical environment of semen can have a profound effect on sperm quality, we examined the effect of pH on the motility, viability and capacitation of human sperm. The sperm in this study was collected from healthy males to avoid interference from other factors. The spermatozoa cultured in sperm nutrition solution at pH 5.2, 6.2, 7.2 and 8.2 were analyzed for sperm total motility, progressive motility (PR), hypo-osmotic swelling (HOS) rate, and sperm penetration. Our results showed that these parameters were similar in pH 7.2 and 8.2 sperm nutrition solutions, but decreased in pH 5.2 and 6.2 solutions. The HOS rate exhibited positive correlation with the sperm total motility and PR. In addition, the sperm Na(+)/K(+)-ATPase activity at different pHs was measured, and the enzyme activity was significantly lower in pH 5.2 and 6.2 media, comparing with that in pH 8.2 and pH 7.2 solutions. Using flow cytometry (FCM) and laser confocal scanning microscopy (LCSM) analysis, the intracellular Ca2(+ )concentrations of sperm cultured in sperm capacitation solution at pH 5.2, 6.2, 7.2 and 8.2 were determined. Compared with that at pH 7.2, the mean fluorescence intensity of sperm in pH 5.2 and 6.2 media decreased significantly, while that of pH 8.2 group showed no difference. Our results suggested that the declined Na(+)/K(+)-ATPase activity at acidic pHs result in decreased sperm movement and capacitation, which could be one of the mechanisms of male infertility.

  11. Standalone BISON Fuel Performance Results for Watts Bar Unit 1, Cycles 1-3

    Energy Technology Data Exchange (ETDEWEB)

    Clarno, Kevin T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pawlowski, Roger [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Stimpson, Shane [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Powers, Jeffrey [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-03-07

    The Consortium for Advanced Simulation of Light Water Reactors (CASL) is moving forward with more complex multiphysics simulations and increased focus on incorporating fuel performance analysis methods. The coupled neutronics/thermal-hydraulics capabilities within the Virtual Environment for Reactor Applications Core Simulator (VERA-CS) have become relatively stable, and major advances have been made in analysis efforts, including the simulation of twelve cycles of Watts Bar Nuclear Unit 1 (WBN1) operation. While this is a major achievement, the VERA-CS approaches for treating fuel pin heat transfer have well-known limitations that could be eliminated through better integration with the BISON fuel performance code. Several approaches are being implemented to consider fuel performance, including a more direct multiway coupling with Tiamat, as well as a more loosely coupled one-way approach with standalone BISON cases. Fuel performance typically undergoes an independent analysis using a standalone fuel performance code with manually specified input defined from an independent core simulator solution or set of assumptions. This report summarizes the improvements made since the initial milestone to execute BISON from VERA-CS output. Many of these improvements were prompted through tighter collaboration with the BISON development team at Idaho National Laboratory (INL). A brief description of WBN1 and some of the VERA-CS data used to simulate it are presented. Data from a small mesh sensitivity study are shown, which helps justify the mesh parameters used in this work. The multi-cycle results are presented, followed by the results for the first three cycles of WBN1 operation, particularly the parameters of interest to pellet-clad interaction (PCI) screening (fuel-clad gap closure, maximum centerline fuel temperature, maximum/minimum clad hoop stress, and cumulative damage index). Once the mechanics of this capability are functioning, future work will target cycles with

  12. Preference and avoidance pH of brook trout Salvelinus fontinalis and brown trout Salmo trutta exposed to different holding pH.

    Science.gov (United States)

    Fost, B A; Ferreri, C P

    2015-08-01

    The goal of this study was to determine if short-term exposure of brook trout Salvelinus fontinalis and brown trout Salmo trutta to a lower pH than found in their source stream results in a shift in preference or avoidance pH. The lack of a shift in preference or avoidance pH of adult S. fontinalis and S. trutta suggests that these species can be held at a pH different from the source waterbody for a short period of time without altering preference or avoidance pH behaviour. © 2015 The Fisheries Society of the British Isles.

  13. Computer simulation of the effect of temperature on pH.

    Science.gov (United States)

    Kipp, J E; Schuck, D F

    1995-11-01

    The effect of temperature on solution pH was simulated by computer (program PHTEMP). We have determined that the change in pH due to shifts in acid-base equilibria [delta pH = pH(60 degrees C) - pH(25 degrees C)] can be substantial for compounds such as aliphatic amines that have high enthalpies for acid dissociation. This is of particular significance during elevated temperature experiments in which changes in the pKa values of formulation components, and hence the solution pH, can accelerate decomposition as compared to those formulations where sensitive functionality is absent. PHTEMP afforded the following results at initial pH = 7 (25 degrees C): (a) 0.1 M triethylamine (delta H zero = 10.4 kcal/mol) delta pH approximately -0.8; (b) 0.1 M acetic acid (delta H zero = -0.1 kcal/mol) delta pH approximately 0; (c) 0.1 M sulfuric acid (delta H zero 1 = -12 kcal/mol; delta H zero 2 = -5.4 kcal/mol) delta pH approximately -0.4. Solutions of general pharmaceutical interest were also studied and included a 12-component amino acid mixture, 0.1 M glycine, and 0.1 M triethylamine in either 0.02 M citric acid or 0.05 M TRIS buffer. In each case the pH change with temperature was dependent on the concentrations of components, the enthalpies for each acid dissociation, and the starting pH. At lower pH ( 9). These results are interpreted as the effect of a relative change in hydronium ion activity, delta H+/H+(initial), due to temperature-induced shifts in equilibria (acid dissociation, water autoprotolysis). This relative change must become larger as H+ decreases (pH increases). The output of PHTEMP was experimentally verified with 0.1 M glycine and with a multiple component amino acid solution. In both cases, agreement with prediction was excellent. The results of this investigation underscore the need to critically review formulation choices for both thermodynamic and traditional kinetic effects on the resulting product stability.

  14. PH sensor

    OpenAIRE

    Artero, C.; Nogueras Cervera, Marc; Manuel Lázaro, Antonio

    2012-01-01

    This paper presents a design of a marine instrument for the measurement of pH in seawater. The measurement system consists of a pH electrode connected to the underwater observatory OBSEA. The extracted data are useful for scientists researching ocean acidification. Peer Reviewed

  15. Dual-Ratiometric Fluorescent Nanoprobe for Visualizing the Dynamic Process of pH and Superoxide Anion Changes in Autophagy and Apoptosis.

    Science.gov (United States)

    Yang, Limin; Chen, Yuanyuan; Yu, Zhengze; Pan, Wei; Wang, Hongyu; Li, Na; Tang, Bo

    2017-08-23

    Autophagy and apoptosis are closely associated with various pathological and physiological processes in cell cycles. Investigating the dynamic changes of intracellular active molecules in autophagy and apoptosis is of great significance for clarifying their inter-relationship and regulating mechanism in many diseases. In this study, we develop a dual-ratiometric fluorescent nanoprobe for quantitatively differentiating the dynamic process of superoxide anion (O 2 •- ) and pH changes in autophagy and apoptosis in HeLa cells. A rhodamine B-loaded mesoporous silica core was used as the reference, and fluorescence probes for pH and O 2 •- measurement were doped in the outer layer shell of SiO 2 . Then, chitosan and triphenylphosphonium were modified on the surface of SiO 2 . The experimental results showed that the nanoprobe is able to simultaneously and precisely visualize the changes of mitochondrial O 2 •- and pH in HeLa cells. The kinetics data revealed that the changes of pH and O 2 •- during autophagy and apoptosis in HeLa cells were significantly different. The pH value was decreased at the early stage of apoptosis and autophagy, whereas the O 2 •- level was enhanced at the early stage of apoptosis and almost unchanged at the initial stage of autophagy. At the late stage of apoptosis and autophagy, the concentration of O 2 •- was increased, whereas the pH was decreased at the late stage of autophagy and almost unchanged at the late stage of apoptosis. We hope that the present results provide useful information for studying the effects of O 2 •- and pH in autophagy and apoptosis in various pathological conditions and diseases.

  16. Seasonal Belowground Ecosystem and Eco-enzymatic Responses to Soil pH and Phosphorus Availability in Temperate Hardwood Forests

    Science.gov (United States)

    Smemo, K. A.; Deforest, J. L.; Petersen, S. L.; Burke, D.; Hewins, C.; Kluber, L. A.; Kyker, S. R.

    2013-12-01

    Atmospheric acid deposition can increase phosphorus (P) limitation in temperate hardwood forests by increasing N availability, and therefore P demand, and/or by decreasing pH and occluding inorganic P. However, only recently have studies demonstrated that P limitation can occur in temperate forests and very little is known about the temporal aspects of P dynamics in acidic forest soils and how seasonal shifts in nutrient availability and demand influence microbial investment in extracellular enzymes. The objectives of this study were to investigate how P availability and soil pH influence seasonal patterns of nutrient cycling and soil microbial activity in hardwood forests that experience chronic acid deposition. We experimentally manipulated soil pH, P, or both for three years and examined soil treatment responses in fall, winter, spring, early summer, and late summer. We found that site (glaciated versus unglaciated) and treatment had the most significant influence on nutrient pools and cycling. In general, nutrient pools were higher in glaciated soils than unglaciated for measured nutrients, including total C and N (2-3 times higher), extractable inorganic nitrogen, and readily available P. Treatment had no impact on total C and N pools in either region, but did affect other measured nutrients such as ammonium, which was greatest in the elevated pH treatment for both sites. As expected, readily available P pools were highest in the elevated P treatments (3 fold increase in both sites), but raising pH decreased available P pools in the glaciated site. Raising soil pH increased both net N mineralization rates and net P mineralization rates, regardless of site. Nitrification responses were complex, but we observed an overall significant nitrification increase under elevated pH, particularly in the growing season. Extracellular enzyme activity showed more seasonal patterns than site and treatment effects, exhibiting significant growing season activity reductions for

  17. Pb and Cd binding to natural freshwater biofilms developed at different pH: the important role of culture pH.

    Science.gov (United States)

    Hua, Xiuyi; Dong, Deming; Ding, Xiaoou; Yang, Fan; Jiang, Xu; Guo, Zhiyong

    2013-01-01

    The effects of solution pH on adsorption of trace metals to different types of natural aquatic solid materials have been studied extensively, but few studies have been carried out to investigate the effect of pH at which the solid materials were formed on the adsorption. The purpose of present study is to examine this effect of culture pH on metal adsorption to natural freshwater biofilms. The adsorption of Pb and Cd to biofilms which were developed at different culture pH values (ranging from 6.5 to 9.0) was measured at the same adsorption pH value (6.5). The culture pH had considerable effects on both composition and metal adsorption ability of the biofilms. Higher culture pH usually promoted the accumulation of organic material and Fe oxides in the biofilms. The culture pH also affected the quantity and species of algae in the biofilms. The adsorption of Pb and Cd to the biofilms generally increased with the increase of culture pH. This increase was minor at lower pH range and significant at higher pH range and was more remarkable for Cd adsorption than for Pb adsorption. The notable contribution of organic material to the adsorption at higher culture pH values was also observed. The profound impacts of culture pH on adsorption behavior of biofilms mainly resulted from the variation of total contents of the biofilm components and were also affected by the alteration of composition and properties of the components.

  18. Comparative study of two modes of gastroesophageal reflux measuring: conventional esophageal pH monitoring and wireless pH monitoring

    Directory of Open Access Journals (Sweden)

    Rimon Sobhi Azzam

    2012-06-01

    Full Text Available CONTEXT: Esophageal pH monitoring is considered to be the gold standard for the diagnosis of gastroesophageal acid reflux. However, this method is very troublesome and considerably limits the patient's routine activities. Wireless pH monitoring was developed to avoid these restrictions. OBJECTIVE: To compare the first 24 hours of the conventional and wireless pH monitoring, positioned 3 cm above the lower esophageal sphincter, in relation to: the occurrence of relevant technical failures, the ability to detect reflux and the ability to correlate the clinical symptoms to reflux. METHODS: Twenty-five patients referred for esophageal pH monitoring and with typical symptoms of gastroesophageal reflux disease were studied prospectively, underwent clinical interview, endoscopy, esophageal manometry and were submitted, with a simultaneous initial period, to 24-hour catheter pH monitoring and 48-hour wireless pH monitoring. RESULTS: Early capsule detachment occurred in one (4% case and there were no technical failures with the catheter pH monitoring (P = 0.463. Percentages of reflux time (total, upright and supine were higher with the wireless pH monitoring (P < 0.05. Pathological gastroesophageal reflux occurred in 16 (64% patients submitted to catheter and in 19 (76% to the capsule (P = 0.355. The symptom index was positive in 12 (48% patients with catheter pH monitoring and in 13 (52% with wireless pH monitoring (P = 0.777. CONCLUSIONS: 1 No significant differences were reported between the two methods of pH monitoring (capsule vs catheter, in regard to relevant technical failures; 2 Wireless pH monitoring detected higher percentages of reflux time than the conventional pH-metry; 3 The two methods of pH monitoring were comparable in diagnosis of pathological gastroesophageal reflux and comparable in correlating the clinical symptoms with the gastroesophageal reflux.

  19. pH- and thermo-responsive microcontainers as potential drug delivery systems: Morphological characteristic, release and cytotoxicity studies.

    Science.gov (United States)

    Efthimiadou, Eleni K; Tapeinos, Christos; Tziveleka, Leto-Aikaterini; Boukos, Nikos; Kordas, George

    2014-04-01

    Polymeric pH- and thermo-sensitive microcontainers (MCs) were developed as a potential drug delivery system for cancer therapy. It is well known that cancer cells exhibit notable characteristics such as acidic pH due to glycolytic cycle and higher temperature due to their higher proliferation rate. Based on these characteristics, we constructed a dual pH- and thermo-sensitive material for specific drug release on the pathological tissue. The MC's fabrication is based on a two-step procedure, in which, the first step involves the core synthesis and the second one is related to the shell formation. The core consists of poly(methyl methacrylate (PMMA), while the shell consists of PMMA, poly(isopropylacrylamide), poly(acrylic acid) and poly(divinylbenzene). Three different types of MCs were synthesized based on the seed polymerization method. The synthesized MCs were characterized structurally by Fourier transform infrared and morphologically by scanning electron microscopy. Dynamic light scattering was also used to study their behavior in aqueous solution under different pH and temperature conditions. For the loading and release study, the anthracycline drug daunorubicin (DNR) was used as a model drug, and its release properties were evaluated under different pH and thermo-conditions. Cytotoxicity studies were also carried out against MCF-7 breast cancer and 3T3 mouse embryonic fibroblast cells. According to our results, the synthesized microcontainers present desired pH and thermo behavior and can be applied in drug delivery systems. It is worth mentioning that the synthesized microcontainers which incorporated the drug DNR exhibit higher toxicity than the free drug. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Skin pH, Atopic Dermatitis, and Filaggrin Mutations

    DEFF Research Database (Denmark)

    Bandier, Josefine; Johansen, Jeanne Duus; Petersen, Lars Jelstrup

    2014-01-01

    mutations may influence skin pH. OBJECTIVE: We aimed to determine the epidermal pH in different groups stratified by filaggrin mutations and atopic dermatitis. Further, we investigated the changes in pH according to severity of mutational status among patients with dermatitis, irrespective of skin condition....... METHODS: pH was measured with a multiprobe system pH probe (PH 905), and the study population was composed of 67 individuals, who had all been genotyped for 3 filaggrin mutations (R501X, 2282del4, R2447X). RESULTS: We found no clear pattern in relation to filaggrin mutation carrier status. Individuals...... with wild-type filaggrin displayed both the most acidic and most alkaline values independent of concomitant skin disease; however, no statistical differences between the groups were found. CONCLUSIONS: The lack of significant diversity in skin pH in relation to filaggrin mutation carrier status suggests...

  1. Regulation of pH During Amelogenesis.

    Science.gov (United States)

    Lacruz, Rodrigo S; Nanci, Antonio; Kurtz, Ira; Wright, J Timothy; Paine, Michael L

    2010-02-01

    During amelogenesis, extracellular matrix proteins interact with growing hydroxyapatite crystals to create one of the most architecturally complex biological tissues. The process of enamel formation is a unique biomineralizing system characterized first by an increase in crystallite length during the secretory phase of amelogenesis, followed by a vast increase in crystallite width and thickness in the later maturation phase when organic complexes are enzymatically removed. Crystal growth is modulated by changes in the pH of the enamel microenvironment that is critical for proper enamel biomineralization. Whereas the genetic bases for most abnormal enamel phenotypes (amelogenesis imperfecta) are generally associated with mutations to enamel matrix specific genes, mutations to genes involved in pH regulation may result in severely affected enamel structure, highlighting the importance of pH regulation for normal enamel development. This review summarizes the intra- and extracellular mechanisms employed by the enamel-forming cells, ameloblasts, to maintain pH homeostasis and, also, discusses the enamel phenotypes associated with disruptions to genes involved in pH regulation.

  2. PhD students: making research and publishing

    Directory of Open Access Journals (Sweden)

    Ioan Sporea, MD, PhD

    2016-12-01

    Full Text Available PhD student time is very interesting in the life of researchers. Many of them are young graduates, without or with very few experience in the field of scientific research. During four years, they must become experts in a narrow field (virtually, the subject of their PhD thesis, but at the same time they have to be trained for research and for publishing. Is it possible? It is mandatory! PhD students start with a one year training in the basic field of research during which they attend different courses regarding how to search the literature, how to perform research, how to perform statistical analysis, how to prepare a paper, where and how to publish and so on. Following this training year, together with their mentor (the coordinator of the PhD thesis, the PhD student starts working on the thesis. And this means reading as much as possible significant published data regarding his/her subject, proper research (basic, experimental, or clinical, and finally preparing papers for publication (in the beginning as abstracts for different meetings and later as original articles in dedicated journals.Participation of PhD students to different meetings is important to improve the quality of their research as an exercise for oral presentations. On the other hand, oral presentation is useful because the paper is open for discussion and corrections can be made during and after the oral presentation. During last ten years, there were organized conferences for PhD students and young doctors, particularly in Târgu Mureș and Timișoara. It was a good opportunity to show results, to discuss and to cooperate.This is why in December 2016, the Doctoral School of Victor Babes University of Medicine and Pharmacy decided to organize a scientific competition between PhD students, in an interesting scientific session. The top 10 PhD students (according to the cumulative Impact Factor of their first author publications were invited to present their scientific research

  3. Effects of 42 deg. C hyperthermia on intracellular pH in ovarian carcinoma cells during acute or chronic exposure to low extracellular pH

    International Nuclear Information System (INIS)

    Wahl, Miriam L.; Bobyock, Suzanne B.; Leeper, Dennis B.; Owen, Charles S.

    1997-01-01

    Purpose: To determine whether intracellular pH (pH i ) is affected during hyperthermia in substrate-attached cells and whether acute extracellular acidification potentiates the cytotoxicity of hyperthermia via an effect on pH i . Methods and Materials: The pH i was determined in cells attached to extracellular matrix proteins loaded with the fluorescent indicator dye BCECF at 37 deg. C and during 42 deg. C hyperthermia at an extracellular pH (pH e ) of 6.7 or 7.3 in cells. Effects on pH i during hyperthermia are compared to effects on clonogenic survival after hyperthermia at pH e 7.3 and 6.7 of cells grown at pH e 7.3, or of cells grown and monitored at pH e 6.7. Results: The results show that pH i values are affected by substrate attachments. Cells attached to extracellular matrix proteins had better signal stability, low dye leakage and evidence of homeostatic regulation of pH i during heating. The net decrease in pH i in cells grown and assayed at pH e = 7.3 during 42 deg. C hyperthermia was 0.28 units and the decrease in low pH adapted cells heated at pH e = 6.7 was 0.14 units. Acute acidification from pH e = 7.3 to pH e = 6.7 at 37 deg. C caused an initial reduction of 0.5-0.8 unit in pH i , but a partial recovery followed during the next 60-90 min. Concurrent 42 deg. C hyperthermia caused the same initial reduction in pH i in acutely acidified cells, but inhibited the partial recovery that occurred during the next 60-90 min at 37 deg. C. After 4 h at 37 deg. C, the net change in pH i in acutely acidified cells was 0.30 pH unit, but at 42 deg. C is 0.63 pH units. The net change in pH i correlated inversely with clonogenic survival. Conclusions: Hyperthermia causes a pH i reduction in cells which was smaller in magnitude by 50% in low pH adapted cells. Hyperthermia inhibited the partial recovery from acute acidification that was observed at 37 deg. C in substrate attached cells, in parallel with a lower subsequent clonogenic survival

  4. Maid (GCIP) is involved in cell cycle control of hepatocytes

    DEFF Research Database (Denmark)

    Sonnenberg-Riethmacher, Eva; Wüstefeld, Torsten; Miehe, Michaela

    2007-01-01

    . Therefore, we studied the role of Maid during cell cycle progression after partial hepatectomy (PH). Lack of Maid expression after PH was associated with a delay in G1/S-phase progression as evidenced by delayed cyclinA expression and DNA replication in Maid-deficient mice. However, at later time points......The function of Maid (GCIP), a cyclinD-binding helix-loop-helix protein, was analyzed by targeted disruption in mice. We show that Maid function is not required for normal embryonic development. However, older Maid-deficient mice-in contrast to wild-type controls--develop hepatocellular carcinomas...

  5. Feasible metabolisms in high pH springs of the Philippines.

    Science.gov (United States)

    Cardace, Dawn; Meyer-Dombard, D'Arcy R; Woycheese, Kristin M; Arcilla, Carlo A

    2015-01-01

    A field campaign targeting high pH, H2-, and CH4-emitting serpentinite-associated springs in the Zambales and Palawan Ophiolites of the Philippines was conducted in 2012-2013, and enabled description of several springs sourced in altered pillow basalts, gabbros, and peridotites. We combine field observations of pH, temperature, conductivity, dissolved oxygen, and oxidation-reduction potential with analyses of major ions, dissolved inorganic carbon, dissolved organic carbon, and dissolved gas phases in order to model the activities of selected phases important to microbial metabolism, and to rank feasible metabolic reactions based on energy yield. We document changing geochemical inventories in these springs between sampling years, and examine how the environment supports or prevents the function of certain microbial metabolisms. In all, this geochemistry-based assessment of feasible metabolisms indicates methane cycling, hydrogen oxidation, some iron and sulfur metabolisms, and ammonia oxidation are feasible reactions in this continental site of serpentinization.

  6. Characterization of pH dependent Mn(II oxidation strategies and formation of a bixbyite-like phase by Mesorhizobium australicum T-G1

    Directory of Open Access Journals (Sweden)

    Tsing eBohu

    2015-07-01

    Full Text Available Despite the ubiquity of Mn oxides in natural environments, there are only a few observations of biological Mn(II oxidation at pH < 6. The lack of low pH Mn-oxidizing bacteria (MOB isolates limits our understanding of how pH influences biological Mn(II oxidation in extreme environments. Here, we report that a novel MOB isolate, Mesorhizobium australicum strain T-G1, isolated from an acidic and metalliferous uranium mining area, can oxidize Mn(II at both acidic and neutral pH using different enzymatic pathways. X-ray diffraction (XRD, Raman spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS revealed that T-G1 initiated bixbyite-like Mn oxide formation at pH 5.5 which coincided with multi-copper oxidase (MCO expression from early exponential phase to late stationary phase. In contrast, reactive oxygen species (ROS, particularly superoxide, appeared to be more important for T-G1 mediated Mn(II oxidation at neutral pH. ROS was produced in parallel with the occurrence of Mn(II oxidation at pH 7.2 from early stationary phase. Solid phase Mn oxides did not precipitate, which is consistent with the presence of a high amount of H2O2 and lower activity of catalase in the liquid culture at pH 7.2. Our results show that M. australicum T-G1, an acid tolerant MOB, can initiate Mn(II oxidation by varying its oxidation mechanisms depending on the pH and may play an important role in low pH manganese biogeochemical cycling.

  7. Optimum gas turbine cycle for combined cycle power plant

    International Nuclear Information System (INIS)

    Polyzakis, A.L.; Koroneos, C.; Xydis, G.

    2008-01-01

    The gas turbine based power plant is characterized by its relatively low capital cost compared with the steam power plant. It has environmental advantages and short construction lead time. However, conventional industrial engines have lower efficiencies, especially at part load. One of the technologies adopted nowadays for efficiency improvement is the 'combined cycle'. The combined cycle technology is now well established and offers superior efficiency to any of the competing gas turbine based systems that are likely to be available in the medium term for large scale power generation applications. This paper has as objective the optimization of a combined cycle power plant describing and comparing four different gas turbine cycles: simple cycle, intercooled cycle, reheated cycle and intercooled and reheated cycle. The proposed combined cycle plant would produce 300 MW of power (200 MW from the gas turbine and 100 MW from the steam turbine). The results showed that the reheated gas turbine is the most desirable overall, mainly because of its high turbine exhaust gas temperature and resulting high thermal efficiency of the bottoming steam cycle. The optimal gas turbine (GT) cycle will lead to a more efficient combined cycle power plant (CCPP), and this will result in great savings. The initial approach adopted is to investigate independently the four theoretically possible configurations of the gas plant. On the basis of combining these with a single pressure Rankine cycle, the optimum gas scheme is found. Once the gas turbine is selected, the next step is to investigate the impact of the steam cycle design and parameters on the overall performance of the plant, in order to choose the combined cycle offering the best fit with the objectives of the work as depicted above. Each alterative cycle was studied, aiming to find the best option from the standpoint of overall efficiency, installation and operational costs, maintainability and reliability for a combined power

  8. Scales and sources of pH and dissolved oxygen variability in a shallow, upwelling-driven ecosystem

    Science.gov (United States)

    Tanner, C. A.; Martz, T.; Levin, L. A.

    2011-12-01

    In the coastal zone extreme variability in carbonate chemistry and oxygen is driven by fluctuations in temperature, salinity, air-sea gas exchange, mixing processes, and biology. This variability appears to be magnified in upwelling-driven ecosystems where low oxygen and low pH waters intrude into shallow depths. The oxygen and carbon chemistry signal can be further confounded by highly productive ecosystems such as kelp beds where photosynthesis and respiration consume and release significant amounts of dissolved inorganic carbon and oxygen. This variability poses a challenge for scientists assessing the impacts of climate change on nearshore ecosystems. We deployed physical & biogeochemical sensors in order to observe these processes in situ. The "SeapHOx" instruments used in this study consist of a modified Honeywell Durafet° ISFET pH sensor, an Aanderra Optode Oxygen sensor, and a SBE-37 conductivity, temperature, pressure sensor. The instruments were deployed on and around the La Jolla Kelp Forest at a variety of depths. Our goals were to (a) characterize the link between pH and oxygen and identify the magnitude of pH and oxygen variability over a range of intra-annual time scales and (b) investigate spatial patterns of pH and oxygen variability associated with depth, proximity to shore, and presence of kelp. Results thus far reveal a strong relationship between oxygen and pH. Temporal variability is greatest at the semidiurnal frequency where pH (at 7 m) can range up to 0.3 units and oxygen can change 50% over 6 h. Diurnal variability is a combination of the diurnal tidal component and diel cycles of production and respiration. Event-scale dynamics associated with upwelling can maintain pH and oxygen below 7.8 units and 200 μmol kg-1, respectively, for multiple days. Frequent current reversals drive changes in the observed oxygen and pH variability. When alongshore currents are flowing southward, driven by upwelling-favorable winds, the magnitude of

  9. Results of Spectral Corona Observations in Solar Activity Cycles 17-24

    Science.gov (United States)

    Aliev, A. Kh.; Guseva, S. A.; Tlatov, A. G.

    2017-12-01

    The results of the work of the global observation network are considered, and a comparative analysis of the data of various coronal observatories is performed. The coronal activity index has been reconstructed for the period 1939-2016 based on the data of various observatories in Kislovodsk system. For this purpose, the corona daily intensity maps from the Sacramento Peak and Lomnický Štít observatories according to the Solar-Geophysical Data journal have been digitized; they supplement the data of other observatories. The homogeneity and continuity of the corona observations at the Kislovodsk station, including activity cycle 24, is confirmed. Unfortunately, the only observatory at present that continues observation of the spectral corona in Fe XIV 5303 Å and Fe XIV 6374 Å lines is the Kislovodsk astronomical station Mountain Astronomical Station (MAS) of the Central Astronomical Observatory, Russian Academy of Sciences (Pulkovo). The data on the combined corona in 5303 Å line are analyzed. It is shown that there is a high correlation of the intensity index of green corona with solar radiation measurements in the vacuum UV region. Data on the beginning of the new 25th activity cycle in the corona at high latitudes are presented.

  10. Stable Fe isotope fractionation during anaerobic microbial dissimilatory iron reduction at low pH

    Science.gov (United States)

    Chanda, P.; Amenabar, M. J.; Boyd, E. S.; Beard, B. L.; Johnson, C.

    2017-12-01

    In low-temperature anaerobic environments microbial dissimilatory iron reduction (DIR) plays an important role in Fe cycling. At neutral pH, sorption of aqueous Fe(II) (Fe(II)aq, produced by DIR) catalyzes isotopic exchange between Fe(II) and solid Fe(III), producing 56Fe/54Fe fractionations on the order of 3‰ during DIR[1,2,3]. At low pH, however, the absence of sorbed Fe(II) produces only limited abiologic isotopic exchange[4]. Here we investigated the scope of isotopic exchange between Fe(II)aq and ferric (hydr)oxides (ferrihydrite and goethite) and the associated stable Fe isotope fractionation during DIR by Acidianus strain DS80 at pH 3.0 and 80°C[5]. Over 19 days, 13% reduction of both minerals via microbial DIR was observed. The δ56Fe values of the fluid varied from -2.31 to -1.63‰ (ferrihydrite) and -0.45 to 0.02‰ (goethite). Partial leaching of bulk solid from each reactor with dilute HCl showed no sorption of Fe(II), and the surface layers of the solids were composed of Fe(III) with high δ56Fe values (ferrihydrite: 0.20 to 0.48‰ and goethite: 1.20 to 1.30‰). These results contrast with the lack of Fe isotope exchange in abiologic low-pH systems and indicate a key role for biology in catalyzing Fe isotope exchange between Fe(II)aq and Fe(III) solids, despite the absence of sorbed Fe(II). The estimated fractionation factor (ΔFeFe(III) -Fe(II)aq 2.6‰) from leaching of ferrihydrite is similar to the abiologic equilibrium fractionation factor ( 3.0‰)[3]. The fractionation factor (ΔFeFe(III) -Fe(II)aq 2.0‰) for goethite is higher than the abiologic fractionation factor ( 1.05‰)[2], but is consistent with the previously proposed "distorted surface layer" of goethite produced during the exchange with Fe(II)aq at neutral pH[1]. This study indicates that significant variations in Fe isotope compositions may be produced in low-pH environments where biological cycling of Fe occurs, in contrast to the expected lack of isotopic fractionation in

  11. Highly Stretchable Potentiometric pH Sensor Fabricated via Laser Carbonization and Machining of Carbon-Polyaniline Composite.

    Science.gov (United States)

    Rahimi, Rahim; Ochoa, Manuel; Tamayol, Ali; Khalili, Shahla; Khademhosseini, Ali; Ziaie, Babak

    2017-03-15

    The development of stretchable sensors has recently attracted considerable attention. These sensors have been used in wearable and robotics applications, such as personalized health-monitoring, motion detection, and human-machine interfaces. Herein, we report on a highly stretchable electrochemical pH sensor for wearable point-of-care applications that consists of a pH-sensitive working electrode and a liquid-junction-free reference electrode, in which the stretchable conductive interconnections are fabricated by laser carbonizing and micromachining of a polyimide sheet bonded to an Ecoflex substrate. This method produces highly porous carbonized 2D serpentine traces that are subsequently permeated with polyaniline (PANI) as the conductive filler, binding material, and pH-sensitive membrane. The experimental and simulation results demonstrate that the stretchable serpentine PANI/C-PI interconnections with an optimal trace width of 0.3 mm can withstand elongations of up to 135% and are robust to more than 12 000 stretch-and-release cycles at 20% strain without noticeable change in the resistance. The pH sensor displays a linear sensitivity of -53 mV/pH (r 2 = 0.976) with stable performance in the physiological range of pH 4-10. The sensor shows excellent stability to applied longitudinal and transverse strains up to 100% in different pH buffer solutions with a minimal deviation of less than ±4 mV. The material biocompatibility is confirmed with NIH 3T3 fibroblast cells via PrestoBlue assays.

  12. Structural match of heterogeneously nucleated Mn(OH)_2(s) nanoparticles on quartz under various pH conditions

    International Nuclear Information System (INIS)

    Jung, Haesung; Lee, Byeongdu; Jun, Young-Shin

    2016-01-01

    The early nucleation stage of Mn (hydr)oxide on mineral surfaces is crucial to understand its occurrence and the cycling of nutrients in environmental systems. However, there are only limited studies on the heterogeneous nucleation of Mn(OH)_2(s) as the initial stage of Mn (hydr)oxide precipitation. Here, we investigated the effect of pH on the initial nucleation of Mn(OH)_2(s) on quartz. Under various pH conditions of 9.8, 9.9, and 10.1, we analyzed the structural matches between quartz and heterogeneously nucleated Mn(OH)_2(s). The structural matches were calculated by measuring lateral and vertical dimensions using grazing incidence small angle X-ray scattering (GISAXS) and atomic force microscopy (AFM), respectively. We found that a poorer structural match occurred at a higher pH than at a lower pH. The faster nucleation at a higher pH condition accounted for the observed poorer structural match. By fitting the structural match using classical nucleation theory, we also calculated the interfacial energy between Mn(OH)_2(s) and water (γ_n_f = 71 ± 7 mJ/m"2). The calculated m values and γ_n_f provided the variance of interfacial energy between quartz and Mn(OH)_2(s): γ_s_n = 262–272 mJ/m"2. As a result, this study provides new qualitative and quantitative information about heterogeneous nucleation on environmentally an abundant mineral surface, quartz, and it offers important underpinnings for understanding the fate and transport of trace ions in environmental systems.

  13. An efficient and sensitive fluorescent pH sensor based on amino functional metal-organic frameworks in aqueous environment.

    Science.gov (United States)

    Xu, Xiao-Yu; Yan, Bing

    2016-04-28

    A pH sensor is fabricated via a reaction between an Al(III) salt and 2-aminoterephthalic acid in DMF which leads to a MOF (Al-MIL-101-NH2) with free amino groups. The Al-MIL-101-NH2 samples show good luminescence and an intact structure in aqueous solutions with pH ranging from 4.0 to 7.7. Given its exceptional stability and pH-dependent fluorescence intensity, Al-MIL-101-NH2 has been applied to fluorescent pH sensing. Significantly, in the whole experimental pH range (4.0-7.7), the fluorescence intensity almost increases with increasing pH (R(2) = 0.99688) which can be rationalized using a linear equation: I = 2.33 pH + 26.04. In addition, error analysis and cycling experiments have demonstrated the accuracy and utilizability of the sensor. In practical applications (PBS and lake water), Al-MIL-101-NH2 also manifests its analytical efficiency in pH sensing. And the samples can be easily isolated from an aqueous solution by incorporating Fe3O4 nanoparticles. Moreover, the possible sensing mechanism based on amino protonation is discussed in detail. This work is on of the few cases for integrated pH sensing systems in aqueous solution based on luminescent MOFs.

  14. Carbon dots with strong excitation-dependent fluorescence changes towards pH. Application as nanosensors for a broad range of pH

    Energy Technology Data Exchange (ETDEWEB)

    Barati, Ali [Faculty of Chemistry, Institute for Advanced Studies in Basic Sciences, Zanjan (Iran, Islamic Republic of); Department of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Shamsipur, Mojtaba, E-mail: mshamsipur@yahoo.com [Department of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Abdollahi, Hamid, E-mail: abd@iasbs.ac.ir [Faculty of Chemistry, Institute for Advanced Studies in Basic Sciences, Zanjan (Iran, Islamic Republic of)

    2016-08-10

    In this study, preparation of novel pH-sensitive N-doped carbon dots (NCDs) using glucose and urea is reported. The prepared NCDs present strong excitation-dependent fluorescence changes towards the pH that is a new behavior from these nanomaterials. By taking advantage of this unique behavior, two separated ratiometric pH sensors using emission spectra of the NCDs for both acidic (pH 2.0 to 8.0) and basic (pH 7.0 to 14.0) ranges of pH are constructed. Additionally, by considering the entire Excitation–Emission Matrix (EEM) of NCDs as analytical signal and using a suitable multivariate calibration method, a broad range of pH from 2.0 to 14.0 was well calibrated. The multivariate calibration method was independent from the concentration of NCDs and resulted in a very low average prediction error of 0.067 pH units. No changes in the predicted pH under UV irradiation (for 3 h) and at high ionic strength (up to 2 M NaCl) indicated the high stability of this pH nanosensor. The practicality of this pH nanosensor for pH determination in real water samples was validated with good accuracy and repeatability. - Highlights: • Novel pH-sensitive carbon dots with strong FL changes towards pH are reported. • Ratiometric FL pH-sensors for both acidic and basic ranges of pH are constructed. • Multivariate calibration methods were used to calibrate a broad range of pH. • Using EEM of carbon dots and ANN, pH from 2.0 to 14.0 was well calibrated. • The pH prediction is stable even at high ionic strength up to 2 M NaCl.

  15. Carbon dots with strong excitation-dependent fluorescence changes towards pH. Application as nanosensors for a broad range of pH

    International Nuclear Information System (INIS)

    Barati, Ali; Shamsipur, Mojtaba; Abdollahi, Hamid

    2016-01-01

    In this study, preparation of novel pH-sensitive N-doped carbon dots (NCDs) using glucose and urea is reported. The prepared NCDs present strong excitation-dependent fluorescence changes towards the pH that is a new behavior from these nanomaterials. By taking advantage of this unique behavior, two separated ratiometric pH sensors using emission spectra of the NCDs for both acidic (pH 2.0 to 8.0) and basic (pH 7.0 to 14.0) ranges of pH are constructed. Additionally, by considering the entire Excitation–Emission Matrix (EEM) of NCDs as analytical signal and using a suitable multivariate calibration method, a broad range of pH from 2.0 to 14.0 was well calibrated. The multivariate calibration method was independent from the concentration of NCDs and resulted in a very low average prediction error of 0.067 pH units. No changes in the predicted pH under UV irradiation (for 3 h) and at high ionic strength (up to 2 M NaCl) indicated the high stability of this pH nanosensor. The practicality of this pH nanosensor for pH determination in real water samples was validated with good accuracy and repeatability. - Highlights: • Novel pH-sensitive carbon dots with strong FL changes towards pH are reported. • Ratiometric FL pH-sensors for both acidic and basic ranges of pH are constructed. • Multivariate calibration methods were used to calibrate a broad range of pH. • Using EEM of carbon dots and ANN, pH from 2.0 to 14.0 was well calibrated. • The pH prediction is stable even at high ionic strength up to 2 M NaCl.

  16. Optimizing the continuum of cycle chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Mathews, James A. [Electric Power Research Institute, Charlotte, NC (United States). Generation Sector, Steam and Cycle Chemistry

    2012-07-15

    In 2011 EPRI issued the fourth (4th) major revision to the cycle chemistry guidelines for fossil plants, re-combining the previously segregated ''treatment'' guidelines into a comprehensive document. As with each of the series of previous revisions, the 2011 updated guidelines focus on the optimization of chemistry practices for maintaining the availability, reliability, and economic performance of fossil power plants. A key element in the development and revision of the guidelines is extensive research conducted over the past fifty (50) plus years. Providing an understanding the elements of the power plant cycle and the interrelationships of the best chemistry practices are a basic tenet of the introductory chapters of the guidelines. The target values for each treatment practice and location in the cycle are discussed with specific emphasis on optimization and customization to achieve excellent corrosion protection and elimination of deposition and component damage and failure. The rationale for proper chemistry is presented; for example properly maintaining oxidizing potentials, impact of temperature on pH control, assuring alkaline (sodium) neutralization for controlling boiler corrosion, and other considerations. (orig.)

  17. Development of an accurate pH measurement methodology for the pore fluids of low pH cementitious materials

    International Nuclear Information System (INIS)

    Alonso, M. C.; Garcia Calvo, J. L.; Walker, C.

    2012-08-01

    The main objective of this project has been the development of an agreed set of protocols for the pH measurement of the pore fluid of a low pH cementitious material. Three protocols have been developed (Chapter 2), a reference method, based on pore fluid expression (PFE), and two routine methods with and without filtering, based on Ex Situ Leaching (ESL) procedures. Templates have been designed on which to record details of the pH measurement for the reference (PFE) method (Appendix C) and the routine (ESL) methods without and with filtering (Appendix D). Preliminary protocols were based on a broad review of the literature (Appendix A) and refined through a series of test experiments of the more critical parameters (Appendix B). After definition of the preliminary protocols, two phases of interlaboratory tests were performed. The first phase (Chapter 3) used the same low pH cement paste and enabled the nine participating laboratories to use, become familiar with and to identify any problems/uncertainties in the preliminary protocols. The reported pH values were subjected to a statistical analysis of the (within laboratory) repeatability and (between-laboratory) reproducibility and so provided a reliability test of the preliminary protocols. The second phase (Chapter 4) of interlaboratory tests used four different candidate low pH cementitious materials in the same nine laboratories, which allowed testing, validation and comparison of the reported pH values, which were obtained using the final protocols for the reference (PFE) and routine (ESL) methods by statistical analysis. The proposed final protocols (Chapter 2) have resulted in the reported pH values having low deviation and high reproducibility and repeatability. This will allow confidence in the pH value when selecting a candidate low pH cementitious material to be used in the engineered component of a high-level nuclear waste repository

  18. Development of an accurate pH measurement methodology for the pore fluids of low pH cementitious materials

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, M. C.; Garcia Calvo, J. L. [The Spanish National Research Council (CSIC), Madrid (Spain); Walker, C. [Japan Atomic Energy Agency (JAEA), Ibaraki (Japan)] [and others

    2012-08-15

    The main objective of this project has been the development of an agreed set of protocols for the pH measurement of the pore fluid of a low pH cementitious material. Three protocols have been developed (Chapter 2), a reference method, based on pore fluid expression (PFE), and two routine methods with and without filtering, based on Ex Situ Leaching (ESL) procedures. Templates have been designed on which to record details of the pH measurement for the reference (PFE) method (Appendix C) and the routine (ESL) methods without and with filtering (Appendix D). Preliminary protocols were based on a broad review of the literature (Appendix A) and refined through a series of test experiments of the more critical parameters (Appendix B). After definition of the preliminary protocols, two phases of interlaboratory tests were performed. The first phase (Chapter 3) used the same low pH cement paste and enabled the nine participating laboratories to use, become familiar with and to identify any problems/uncertainties in the preliminary protocols. The reported pH values were subjected to a statistical analysis of the (within laboratory) repeatability and (between-laboratory) reproducibility and so provided a reliability test of the preliminary protocols. The second phase (Chapter 4) of interlaboratory tests used four different candidate low pH cementitious materials in the same nine laboratories, which allowed testing, validation and comparison of the reported pH values, which were obtained using the final protocols for the reference (PFE) and routine (ESL) methods by statistical analysis. The proposed final protocols (Chapter 2) have resulted in the reported pH values having low deviation and high reproducibility and repeatability. This will allow confidence in the pH value when selecting a candidate low pH cementitious material to be used in the engineered component of a high-level nuclear waste repository.

  19. Measurement of the Extracellular pH of Adherently Growing Mammalian Cells with High Spatial Resolution Using a Voltammetric pH Microsensor.

    Science.gov (United States)

    Munteanu, Raluca-Elena; Stǎnicǎ, Luciana; Gheorghiu, Mihaela; Gáspár, Szilveszter

    2018-05-15

    There are only a few tools suitable for measuring the extracellular pH of adherently growing mammalian cells with high spatial resolution, and none of them is widely used in laboratories around the world. Cell biologists very often limit themselves to measuring the intracellular pH with commercially available fluorescent probes. Therefore, we built a voltammetric pH microsensor and investigated its suitability for monitoring the extracellular pH of adherently growing mammalian cells. The voltammetric pH microsensor consisted of a 37 μm diameter carbon fiber microelectrode modified with reduced graphene oxide and syringaldazine. While graphene oxide was used to increase the electrochemically active surface area of our sensor, syringaldazine facilitated pH sensing through its pH-dependent electrochemical oxidation and reduction. The good sensitivity (60 ± 2.5 mV/pH unit), reproducibility (coefficient of variation ≤3% for the same pH measured with 5 different microsensors), and stability (pH drift around 0.05 units in 3 h) of the built voltammetric pH sensors were successfully used to investigate the acidification of the extracellular space of both cancer cells and normal cells. The results indicate that the developed pH microsensor and the perfected experimental protocol based on scanning electrochemical microscopy can reveal details of the pH regulation of cells not attainable with pH sensors lacking spatial resolution or which cannot be reproducibly positioned in the extracellular space.

  20. GREET 1.5 - transportation fuel-cycle model - Vol. 1 : methodology, development, use, and results

    International Nuclear Information System (INIS)

    Wang, M. Q.

    1999-01-01

    This report documents the development and use of the most recent version (Version 1.5) of the Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) model. The model, developed in a spreadsheet format, estimates the full fuel-cycle emissions and energy associated with various transportation fuels and advanced vehicle technologies for light-duty vehicles. The model calculates fuel-cycle emissions of five criteria pollutants (volatile organic compounds, carbon monoxide, nitrogen oxides, particulate matter with diameters of 10 micrometers or less, and sulfur oxides) and three greenhouse gases (carbon dioxide, methane, and nitrous oxide). The model also calculates total energy consumption, fossil fuel consumption, and petroleum consumption when various transportation fuels are used. The GREET model includes the following cycles: petroleum to conventional gasoline, reformulated gasoline, conventional diesel, reformulated diesel, liquefied petroleum gas, and electricity via residual oil; natural gas to compressed natural gas, liquefied natural gas, liquefied petroleum gas, methanol, Fischer-Tropsch diesel, dimethyl ether, hydrogen, and electricity; coal to electricity; uranium to electricity; renewable energy (hydropower, solar energy, and wind) to electricity; corn, woody biomass, and herbaceous biomass to ethanol; soybeans to biodiesel; flared gas to methanol, dimethyl ether, and Fischer-Tropsch diesel; and landfill gases to methanol. This report also presents the results of the analysis of fuel-cycle energy use and emissions associated with alternative transportation fuels and advanced vehicle technologies to be applied to passenger cars and light-duty trucks

  1. Local pH at the surface of hen egg white lysozyme

    Science.gov (United States)

    Otosu, Takuhiro; Kobayashi, Kaito; Yamaguchi, Shoichi

    2018-02-01

    The microenvironment at the surface of hen-egg-white lysozyme (HEWL) was examined by analyzing the change in pKa of fluorescein isothiocyanate (FITC) upon binding to the N-terminus of HEWL. The result showed that the local pH at the HEWL surface is higher than the bulk pH. Furthermore, the data showed that the difference between the local and bulk pH becomes larger with decreasing pH, suggesting HEWL repels more protons at lower pH. Because the local pH affects the protonation states of functional amino-acids at the protein surface, the results provide the fundamental insight into the microenvironment at the protein surface.

  2. Results of cycling with battery charging management; Resultats de cyclage avec gestion de charge au niveau batterie

    Energy Technology Data Exchange (ETDEWEB)

    Verniolle, J.; Fernandez, C. [European Space Research and Technology Centre, Noordwijk (Netherlands)

    1996-12-31

    In order to investigate the charging mode of an in-series assembly of lithium-carbon battery cells, a test has been performed on 5 commercial cells (18650) of 0.95 Ah nominal capacity. Results show that it is possible to cycle the cells at 80% of their output capacities during more than 2000 cycles. The management of the battery consists in maintaining a constant battery voltage as soon as a cell reaches its limit voltage during constant current charging. The initial dispersion of cells has been maintained practically constant during the cycling and the charge state of all cells has decreased progressively. (J.S.)

  3. Results of cycling with battery charging management; Resultats de cyclage avec gestion de charge au niveau batterie

    Energy Technology Data Exchange (ETDEWEB)

    Verniolle, J; Fernandez, C [European Space Research and Technology Centre, Noordwijk (Netherlands)

    1997-12-31

    In order to investigate the charging mode of an in-series assembly of lithium-carbon battery cells, a test has been performed on 5 commercial cells (18650) of 0.95 Ah nominal capacity. Results show that it is possible to cycle the cells at 80% of their output capacities during more than 2000 cycles. The management of the battery consists in maintaining a constant battery voltage as soon as a cell reaches its limit voltage during constant current charging. The initial dispersion of cells has been maintained practically constant during the cycling and the charge state of all cells has decreased progressively. (J.S.)

  4. Genipin Cross-Linked Chitosan-Polyvinylpyrrolidone Hydrogels: Influence of Composition and Postsynthesis Treatment on pH Responsive Behaviour

    Directory of Open Access Journals (Sweden)

    Chinyelumndu Jennifer Nwosu

    2015-01-01

    Full Text Available Understanding the factors that influence the pH responsive behaviour of biocompatible cross-linked hydrogel networks is essential when aiming to synthesise a mechanically stable and yet stimuli responsive material suitable for various applications including drug delivery and tissue engineering. In this study the behaviour of intelligent chitosan-polyvinylpyrrolidone-genipin cross-linked hydrogels is examined as a function of their composition and postsynthesis treatment. Hydrogels are synthesised with varying amounts of each component (chitosan, polyvinylpyrrolidone, and genipin and their response in a pH 2 buffer is measured optically. The influence of postsynthesis treatment on stability and smart characteristics is assessed using selected hydrogel samples synthesised at 30, 40, and 50°C. After synthesis, samples are exposed to either continuous freezing or three freeze-thaw cycles resulting in increased mechanical stability for all samples. Further morphological and mechanical characterisations have aided the understanding of how postsynthesis continual freezing or freeze-thaw manipulation affects network attributes.

  5. Alkaline pH sensor molecules.

    Science.gov (United States)

    Murayama, Takashi; Maruyama, Ichiro N

    2015-11-01

    Animals can survive only within a narrow pH range. This requires continual monitoring of environmental and body-fluid pH. Although a variety of acidic pH sensor molecules have been reported, alkaline pH sensor function is not well understood. This Review describes neuronal alkaline pH sensors, grouped according to whether they monitor extracellular or intracellular alkaline pH. Extracellular sensors include the receptor-type guanylyl cyclase, the insulin receptor-related receptor, ligand-gated Cl- channels, connexin hemichannels, two-pore-domain K+ channels, and transient receptor potential (TRP) channels. Intracellular sensors include TRP channels and gap junction channels. Identification of molecular mechanisms underlying alkaline pH sensing is crucial for understanding how animals respond to environmental alkaline pH and how body-fluid pH is maintained within a narrow range. © 2015 Wiley Periodicals, Inc.

  6. Life cycle test results of a bipolar nickel hydrogen battery

    Science.gov (United States)

    Cataldo, R. L.

    1985-01-01

    A history is given of low Earth orbit (LEO) laboratory test data on a 6.5 ampere-hour bipolar nickel hydrogen battery designed and built at the NASA Lewis Research Center. The bipolar concept is a means of achieving the goal of producing an acceptable battery, of higher energy density, able to withstand the demands of low-Earth-orbit regimes. Over 4100 LEO cycles were established on a ten cell battery. It seems that any perturbation on normal cycling effects the cells performance. Explanations and theories of the battery's behavior are varied and widespread among those closely associated with it. Deep discharging does provide a reconditioning effect and further experimentation is planned in this area. The battery watt-hour efficiency is about 75 percent and the time averaged, discharge voltage is about 1.26 volts for all cells at both the C/4 and LEO rate. Since a significant portion of the electrode capacity has degraded, the LEO cycle discharges are approaching depths of 90 to 100 percent of the high rate capacity. Therefore, the low end-of-discharge voltages occur precipitously after the knee of the discharge curve and is more an indication of electrode capacity and is a lesser indicator of overall cell performance.

  7. Outline of results of safety research (in nuclear fuel cycle field in fiscal year 1996)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-01

    The safety research in Power Reactor and Nuclear Fuel Development Corporation in fiscal year 1996 has been carried out based on the basic plan of safety research (from fiscal year 1996 to 2000) which was decided in March, 1996. In this report, on nuclear fuel cycle field, namely all the subjects in the fields of nuclear fuel facilities, environmental radioactivity and waste disposal, and the subjects related to nuclear fuel facilities among the fields of aseismatic and probabilistic safety assessments, the results of research in fiscal year 1996, the first year of the 5-year project, are summarized together with the outline of the basic plan of safety research. The basic policy, objective and system for promotion of the safety research are described. The objectives of the safety research are the advancement of safety technology, the safety of facilities, stable operation techniques, the safety design and the evaluation techniques of next generation facilities, and the support of transferring nuclear fuel cycle to private businesses. The objects of the research are uranium enrichment, fuel fabrication and reprocessing, and waste treatment and storage. 52 investigation papers of the results of the safety research in nuclear fuel cycle field in fiscal year 1996 are collected in this report. (K.I.)

  8. Method for producing rapid pH changes

    Science.gov (United States)

    Clark, J.H.; Campillo, A.J.; Shapiro, S.L.; Winn, K.R.

    A method of initiating a rapid pH change in a solution comprises irradiating the solution with an intense flux of electromagnetic radiation of a frequency which produces a substantial pK change to a compound in solution. To optimize the resulting pH change, the compound being irradiated in solution should have an excited state lifetime substantially longer than the time required to establish an excited state acid-base equilibrium in the solution. Desired pH changes can be accomplished in nanoseconds or less by means of picosecond pulses of laser radiation.

  9. Dysregulated pH in Tumor Microenvironment Checkmates Cancer Therapy

    Directory of Open Access Journals (Sweden)

    Jaleh Barar

    2013-12-01

    Full Text Available Introduction: The dysregulation of pH by cancerous cells of solid tumors is able to create a unique milieu that is in favor of progression, invasion and metastasis as well as chemo-/immuno-resistance traits of solid tumors. Bioelements involved in pH dysregulation provide new set of oncotargets, inhibition of which may result in better clinical outcome. Methods: To study the impacts of pH dysregulation, we investigated the tumor development and progression in relation with Warburg effect, glycolysis and formation of aberrant tumor microenvironment. Results: The upregulation of glucose transporter GLUT-1 and several enzymes involve in glycolysis exacerbates this phenomenon. The accumulation of lactic acids in cancer cells provokes upregulation of several transport machineries (MCT-1, NHE-1, CA IX and H+ pump V-ATPase resulting in reinforced efflux of proton into extracellular fluid. This deviant event makes pH to be settled at 7.4 and 6.6 respectively in cancer cells cytoplasm and extracellular fluid within the tumor microenvironment, which in return triggers secretion of lysosomal components (various enzymes in acidic milieu with pH 5 into cytoplasm. All these anomalous phenomena make tumor microenvironment (TME to be exposed to cocktail of various enzymes with acidic pH, upon which extracellular matrix (ECM can be remodeled and even deformed, resulting in emergence of a complex viscose TME with high interstitial fluid pressure. Conclusion: It seems that pH dysregulation is able to remodel various physiologic functions and make solid tumors to become much more invasive and metastatic. It also can cause undesired resistance to chemotherapy and immunotherapy. Hence, cancer therapy needs to be reinforced using specific inhibitors of bioelements involved in pH dysregulation of TME in solid tumors.

  10. The effects of extracellular pH and hydroxycinnamic acids influence the intracellular pH of Brettanomyces bruxellensis DSM 7001

    DEFF Research Database (Denmark)

    Campolongo, Simona; Siegumfeldt, Henrik; Aabo, Thomas Ask

    2014-01-01

    and intracellular pH changes in B. bruxellensis DSM 7001, in response to extracellular pH, as well as to the presence of an energy source and hydroxycinnamic acids, have been investigated in this paper by means of Fluorescent Ratio Imaging Microscopy (FRIM). The results show that B. bruxellensis DSM 7001 is able...

  11. Microneedle pH Sensor: Direct, Label-Free, Real-Time Detection of Cerebrospinal Fluid and Bladder pH.

    Science.gov (United States)

    Mani, Ganesh Kumar; Miyakoda, Kousei; Saito, Asuka; Yasoda, Yutaka; Kajiwara, Kagemasa; Kimura, Minoru; Tsuchiya, Kazuyoshi

    2017-07-05

    Acid-base homeostasis (body pH) inside the body is precisely controlled by the kidneys and lungs and buffer systems, such that even a minor pH change could severely affect many organs. Blood and urine pH tests are common in day-to-day clinical trials and require little effort for diagnosis. There is always a great demand for in vivo testing to understand more about body metabolism and to provide effective diagnosis and therapy. In this article, we report the simple fabrication of microneedle-based direct, label-free, and real-time pH sensors. The reference and working electrodes were Ag/AgCl thick films and ZnO thin films on tungsten (W) microneedles, respectively. The morphological and structural characteristics of microneedles were carefully investigated through various analytical methods. The developed sensor exhibited a Nernstian response of -46 mV/pH. Different conditions were used to test the sensor to confirm their accuracy and stability, such as various buffer solutions, with respect to time, and we compared the reading with commercial pH electrodes. Besides that, the fabricated microneedle sensor ability is proven by in vivo testing in mouse cerebrospinal fluid (CSF) and bladders. The pH sensor procedure reported here is totally reversible, and results were reproducible after several rounds of testing.

  12. Corrosion of zirconium alloys in alternating pH environment

    International Nuclear Information System (INIS)

    Mayer, P.; Manolescu, A.V.

    1985-01-01

    Behaviour of two commercial alloys, Zircaloy-2 and zirconium-2.5 wt% niobium were investigated in an environment of alternating pH. Corrosion advancement and scale morphology of coupons exposed to aqueous solution of LiOH (pH 10.2 and 14) were followed as a function of temperature (300-360 degreesC) and time (up to 165 days). The test sequence consisted of short term exposure to high pH and re-exposure to low pH solutions for extended period of time followed by a short term test in high pH. The results of these tests and detailed post-corrosion analysis indicate a fundamental difference between the corrosion behaviour of these two materials. Both alloys corrode fast in high pH environments, but only zirconium-2.5 wt% niobium continues to form detectable new oxide in low pH solution

  13. Compartment-specific pH monitoring in Bacillus subtilis using fluorescent sensor proteins; a tool to analyse the antibacterial effect of weak organic acids.

    Directory of Open Access Journals (Sweden)

    Johan W.A. van Beilen

    2013-06-01

    Full Text Available The internal pH (pHi of a living cell is one of its most important physiological parameters. To monitor the pH inside B. subtilis during various stages of its life cycle, we constructed an improved version (IpHluorin of the ratiometric, pH-sensitive fluorescent protein pHluorin by extending it at the 5’ end with the first 24 bp of comGA. The new version, which showed an approximate 40% increase in fluorescence intensity, was expressed from developmental phase-specific, native promoters of B. subtilis that are specifically active during vegetative growth on glucose (PptsG or during sporulation (PspoIIA, PspoIIID and PsspE. Our results show strong, compartment-specific expression of IpHluorin that allowed accurate pHi measurements of live cultures during exponential growth, early and late sporulation, spore germination, and during subsequent spore outgrowth. Dormant spores were characterised by an internal pH of 6.0 ± 0.3. Upon full germination the internal pH rose dependent on the medium to 7.0-7.4. The presence of sorbic acid in the germination medium inhibited a rise in the intracellular pH of germinating spores and inhibited germination. Such effects were absent when acetic was added at identical concentrations.

  14. Effect of pH on radiation-induced apoptosis

    International Nuclear Information System (INIS)

    Chang, W. Song; Park, Heon J.; Lyons, John C.; Auger, Elizabeth A.; Lee, Hyung-Sik

    1996-01-01

    Purpose/Objective: The effect of environmental pH on the radiation-induced apoptosis in tumor cells in vitro was investigated. Materials and Methods: SCK mammary adenocarcinoma cells of A/J mice were irradiated with γ-rays using a 137 Cs irradiator and incubated in media of different pHs. After incubation at 37 degree sign C for 24-120 hrs., the extent of apoptosis was determined using agarose gel electrophoresis of DNA, in situ TUNEL staining, flow cytometry, and release of 3 H from 3 H-thymidine labeled cells. The membrane integrity, using the trypan blue exclusion method, and the clonogenicity of the cells were also determined. Results: Irradiation with 2-12 Gy of γ-rays induced apoptosis in pH 7.5 medium within 48 hrs. The radiation-induced apoptosis progressively declined as the medium pH was lowered so that little apoptosis occurred in 48 hrs. after irradiation with 12 Gy in pH 6.6 medium. However, when the cells were irradiated and incubated for 48 hrs. in pH 6.6 medium and then medium was replaced with pH 7.5 medium, apoptosis promptly occurred. Apoptosis also occurred even in pH 6.6 medium when the cells were irradiated and maintained in pH 7.5 medium for 8 hrs. or longer post-irradiation before incubation in pH 6.6 medium. Conclusion: An acidic environment markedly suppresses radiation-induced apoptosis probably by suppressing the expression of initial signals responsible for irradiation-induced apoptosis. Indications are that the signals persist in an acidic environment and trigger apoptosis when the environmental acidity is eased. Our results suggest that the acidic environment in human tumors may inhibit the apoptosis after irradiation. However, apoptosis may be triggered when reoxygenation occurs after irradiation, and thus, the intratumor environment becomes less acidic after irradiation. Not only the change in pO 2 but the change in pH during the course of fractionated radiotherapy may greatly influence the outcome of the treatment

  15. A graphene oxide pH sensor for wound monitoring.

    Science.gov (United States)

    Melai, B; Salvo, P; Calisi, N; Moni, L; Bonini, A; Paoletti, C; Lomonaco, T; Mollica, V; Fuoco, R; Di Francesco, F

    2016-08-01

    This article describes the fabrication and characterization of a pH sensor for monitoring the wound status. The pH sensitive layer consists of a graphene oxide (GO) layer obtained by drop-casting 5 μΐ of GO dispersion onto the working electrode of a screen-printed substrate. Sensitivity was 31.8 mV/pH with an accuracy of 0.3 unit of pH. Open-circuit potentiometry was carried out to measure pH in an exudate sample. The GO pH sensor proved to be reliable as the comparison with results obtained from a standard glass electrode pH-meter showed negligible differences (pH units in the worst case) for measurements performed over a period of 4 days.

  16. Several perspectives on water-chemical cycles for nuclear power stations equipped with type VVER and RBMK reactors

    International Nuclear Information System (INIS)

    Mamet, A.P.; Mamet, V.A.; Pashevich, V.I.; Nazarenko, P.N.

    1982-01-01

    Water-chemical cycles for loops I and II of VVER reactors are discussed. These cycles are mixed ammonia-sodium with a variable concentration of boric acid and ammonia hydrazine with a pH factor of 9.1 +/- 0.1. New water-chemical cycles are considered for use in both existing and new nuclear power plants. Application of these new water-chemical cycles showed produce a significant improvement in operating conditions of nuclear power plants. Upon accumulation of sufficient operating experience with these cycles, it should be possible to raise the issue of revising applicable standard documentation

  17. pH sensitive quantum dot-anthraquinone nanoconjugates

    Science.gov (United States)

    Ruedas-Rama, Maria Jose; Hall, Elizabeth A. H.

    2014-05-01

    Semiconductor quantum dots (QDs) have been shown to be highly sensitive to electron or charge transfer processes, which may alter their optical properties. This feature can be exploited for different sensing applications. Here, we demonstrate that QD-anthraquinone conjugates can function as electron transfer-based pH nanosensors. The attachment of the anthraquinones on the surface of QDs results in the reduction of electron hole recombination, and therefore a quenching of the photoluminescence intensity. For some anthraquinone derivatives tested, the quenching mechanism is simply caused by an electron transfer process from QDs to the anthraquinone, functioning as an electron acceptor. For others, electron transfer and energy transfer (FRET) processes were found. A detailed analysis of the quenching processes for CdSe/ZnS QD of two different sizes is presented. The photoluminescence quenching phenomenon of QDs is consistent with the pH sensitive anthraquinone redox chemistry. The resultant family of pH nanosensors shows pKa ranging ˜5-8, being ideal for applications of pH determination in physiological samples like blood or serum, for intracellular pH determination, and for more acidic cellular compartments such as endosomes and lysosomes. The nanosensors showed high selectivity towards many metal cations, including the most physiologically important cations which exist at high concentration in living cells. The reversibility of the proposed systems was also demonstrated. The nanosensors were applied in the determination of pH in samples mimicking the intracellular environment. Finally, the possibility of incorporating a reference QD to achieve quantitative ratiometric measurements was investigated.

  18. pH sensitive quantum dot–anthraquinone nanoconjugates

    International Nuclear Information System (INIS)

    Ruedas-Rama, Maria Jose; Hall, Elizabeth A H

    2014-01-01

    Semiconductor quantum dots (QDs) have been shown to be highly sensitive to electron or charge transfer processes, which may alter their optical properties. This feature can be exploited for different sensing applications. Here, we demonstrate that QD-anthraquinone conjugates can function as electron transfer-based pH nanosensors. The attachment of the anthraquinones on the surface of QDs results in the reduction of electron hole recombination, and therefore a quenching of the photoluminescence intensity. For some anthraquinone derivatives tested, the quenching mechanism is simply caused by an electron transfer process from QDs to the anthraquinone, functioning as an electron acceptor. For others, electron transfer and energy transfer (FRET) processes were found. A detailed analysis of the quenching processes for CdSe/ZnS QD of two different sizes is presented. The photoluminescence quenching phenomenon of QDs is consistent with the pH sensitive anthraquinone redox chemistry. The resultant family of pH nanosensors shows pK a ranging ∼5–8, being ideal for applications of pH determination in physiological samples like blood or serum, for intracellular pH determination, and for more acidic cellular compartments such as endosomes and lysosomes. The nanosensors showed high selectivity towards many metal cations, including the most physiologically important cations which exist at high concentration in living cells. The reversibility of the proposed systems was also demonstrated. The nanosensors were applied in the determination of pH in samples mimicking the intracellular environment. Finally, the possibility of incorporating a reference QD to achieve quantitative ratiometric measurements was investigated

  19. Functional characterization of PhGR and PhGRL1 during flower senescence in the petunia.

    Science.gov (United States)

    Yang, Weiyuan; Liu, Juanxu; Tan, Yinyan; Zhong, Shan; Tang, Na; Chen, Guoju; Yu, Yixun

    2015-09-01

    Petunia PhGRL1 suppression accelerated flower senescence and increased the expression of the genes downstream of ethylene signaling, whereas PhGR suppression did not. Ethylene plays an important role in flowers senescence. Homologous proteins Green-Ripe and Reversion to Ethylene sensitivity1 are positive regulators of ethylene responses in tomato and Arabidopsis, respectively. The petunia flower has served as a model for the study of ethylene response during senescence. In this study, petunia PhGR and PhGRL1 expression was analyzed in different organs, throughout floral senescence, and after exogenous ethylene treatment; and the roles of PhGR and PhGRL1 during petunia flower senescence were investigated. PhGRL1 suppression mediated by virus-induced gene silencing accelerated flower senescence and increased ethylene production; however, the suppression of PhGR did not. Taken together, these data suggest that PhGRL1 is involved in negative regulation of flower senescence, possibly via ethylene production inhibition and consequently reduced ethylene signaling activation.

  20. Plant based dietary supplement increases urinary pH

    Directory of Open Access Journals (Sweden)

    Rao A Venket

    2008-11-01

    Full Text Available Abstract Background Research has demonstrated that the net acid load of the typical Western diet has the potential to influence many aspects of human health, including osteoporosis risk/progression; obesity; cardiovascular disease risk/progression; and overall well-being. As urinary pH provides a reliable surrogate measure for dietary acid load, this study examined whether a plant-based dietary supplement, one marketed to increase alkalinity, impacts urinary pH as advertised. Methods Using pH test strips, the urinary pH of 34 healthy men and women (33.9 +/- 1.57 y, 79.3 +/- 3.1 kg was measured for seven days to establish a baseline urinary pH without supplementation. After this initial baseline period, urinary pH was measured for an additional 14 days while participants ingested the plant-based nutritional supplement. At the end of the investigation, pH values at baseline and during the treatment period were compared to determine the efficacy of the supplement. Results Mean urinary pH statistically increased (p = 0.03 with the plant-based dietary supplement. Mean urinary pH was 6.07 +/- 0.04 during the baseline period and increased to 6.21 +/- 0.03 during the first week of treatment and to 6.27 +/- 0.06 during the second week of treatment. Conclusion Supplementation with a plant-based dietary product for at least seven days increases urinary pH, potentially increasing the alkalinity of the body.

  1. Differential Sensor for PH Monitoring of Environmental Objects

    Directory of Open Access Journals (Sweden)

    Romanenko Sergey

    2016-01-01

    Full Text Available Differential pH sensor is proposed. Reference electrode and measuring electrode are the same type. Reference electrode is immersed in standard buffer solution with known pH value. The differential pH sensor has longer service life as compared with the traditionally used sensors with silver chloride reference electrode. Ultrasonic cleaning system is proposed to clean the primary measuring transducer from pollution that form as result of silting during long-term operation with the sensor.

  2. Alternative ORC bottoming cycles FOR combined cycle power plants

    International Nuclear Information System (INIS)

    Chacartegui, R.; Sanchez, D.; Munoz, J.M.; Sanchez, T.

    2009-01-01

    In this work, low temperature Organic Rankine Cycles are studied as bottoming cycle in medium and large scale combined cycle power plants. The analysis aims to show the interest of using these alternative cycles with high efficiency heavy duty gas turbines, for example recuperative gas turbines with lower gas turbine exhaust temperatures than in conventional combined cycle gas turbines. The following organic fluids have been considered: R113, R245, isobutene, toluene, cyclohexane and isopentane. Competitive results have been obtained for toluene and cyclohexane ORC combined cycles, with reasonably high global efficiencies. The paper is structured in four main parts. A review of combined cycle and ORC cycle technologies is presented, followed by a thermodynamic analysis of combined cycles with commercial gas turbines and ORC low temperature bottoming cycles. Then, a parametric optimization of an ORC combined cycle plant is performed in order to achieve a better integration between these two technologies. Finally, some economic considerations related to the use of ORC in combined cycles are discussed.

  3. Vehicle lightweighting vs. electrification: Life cycle energy and GHG emissions results for diverse powertrain vehicles

    International Nuclear Information System (INIS)

    Lewis, Anne Marie; Kelly, Jarod C.; Keoleian, Gregory A.

    2014-01-01

    Highlights: • We modeled life cycle energy and greenhouse gas (GHG) emissions from diverse powertrain vehicles. • Lightweight versions of the vehicle models were compared against baseline models. • Maximum energy and GHG emissions occur with aluminum vs. advanced high strength steel. • Design harmonization method shows 0.2–0.3 kg of support required per 1 kg powertrain mass increase. - Abstract: This work assesses the potential of electrified vehicles and mass reduction to reduce life cycle energy and greenhouse gas (GHG) emissions. Life cycle assessment (LCA) is used to account for processes upstream and downstream of the vehicle operation, thereby incorporating regional variation of energy and GHG emissions due to electricity production and distinct energy and GHG emissions due to conventional and lightweight materials. Design harmonization methods developed in previous work are applied to create baseline and lightweight vehicle models of an internal combustion vehicle (ICV), hybrid electric vehicle (HEV) and plug-in hybrid electric vehicle (PHEV). Thus, each vehicle is designed to be functionally equivalent and incorporate the structural support required for heavier powertrains. Lightweight vehicles are designed using body-in-white (BIW) mass reduction scenarios with aluminum and advanced/high strength steel (A/HSS). For the mass reduction scenarios considered in this work, results indicate that the greatest life cycle energy and GHG emissions reductions occur when steel is replaced by aluminum. However, since A/HSS requires less energy to produce as compared to aluminum, the energy and GHG reductions per unit mass removed is greatest for A/HSS. Results of the design harmonization modeling method show that 0.2–0.3 kg of structural support is required per unit increase in powertrain mass, thus extending previous methods

  4. Zirconium oxide crystal phase: The role of the pH and time to attain the final pH for precipitation of the hydrous oxide

    International Nuclear Information System (INIS)

    Srinivasan, R.; Harris, M.B.; Simpson, S.F.; De Angelis, R.J.; Davis, B.H.

    1988-01-01

    Precipitated hydrous zirconium oxide can be calcined to produce either a monoclinic or tetragonal product. It has been observed that the time taken to attain the final pH of the solution in contact with the precipitate plays a dominant role in determining the crystal structure of the zirconium oxide after calcination at 500 0 C. The dependence of crystal structure on the rate of precipitation is observed only in the pH range 7--11. Rapid precipitation in this pH range yields predominately monoclinic zirconia, whereas slow (8 h) precipitation produces the tetragonal phase. At pH of approximately 13.0, only the tetragonal phase is formed from both slowly and rapidly precipitated hydrous oxide. The present results, together with earlier results, show that both the pH of the supernatant liquid and the time taken to attain this pH play dominant roles in determining the crystal structure of zirconia that is formed after calcination of the hydrous oxide. The factors that determine the crystal phase are therefore imparted in a mechanism of precipitation that depends upon the pH, and it is inferred that it is the hydroxyl concentration that is the dominant factor

  5. Results on safety research for five years (from fiscal year 1996 to 2000). A field of nuclear fuel cycle

    International Nuclear Information System (INIS)

    2001-10-01

    This safety research carried out by the Japan Nuclear Cycle Development Institute (JNC) for five years ranged from fiscal year 1996 to 2000, was performed according to the safety research basic plan (from fiscal year 1996 to 2000) established on March, 1996 (revised again on May, 2000). This report was arranged on a field on nuclear fuel cycle (all subjects on fields of nuclear fuel facility, environmental radioactivity and radioactive wastes and a subject on nuclear fuel cycle in a field of seismic resistant and probabilistic safety assessment) by combining its research results for five years ranged from 1996 to 2000 fiscal year with general outlines on the safety research basic plan. Here were shown outlines on the safety research basic plan, aims and subjects on safety research at a field of nuclear fuel cycle, a list of survey sheets on safety research result, and survey sheets on safety research results. The survey sheets containing research field, title, organization, researcher name, researching period, names of cooperative organization, using facilities, research outline, research results, established contents, application, and research trends, are ranged to 21 items on nuclear fuel facility, 1 item on seismic resistance, 2 items on probabilistic safety assessment, 8 items on environmental radioactivity, and 20 items on radioactive wastes. (G.K.)

  6. Data on soil PH of Barddhaman district, India

    Directory of Open Access Journals (Sweden)

    Sumanta Bid

    2017-06-01

    Full Text Available PH (Puissance de Hydrogen is an essential ingredient of soil that effects on fertility and productivity of dirt. Barddhaman district is a part of Lower Gangetic Plain fully covered by alluvial soil and popularly known as ‘rice bowl of West Bengal’ owing to its lofty production. This data article provides a block level data on soil PH that is essential for further investigation of the relationship among soil ph, plant growth, plant health and productivity. This data is valuable in the field of soil geography and soil science. Soil PH data is more relevant in the ground of plant biology, agricultural geography and agricultural science. It helps to explain the acidic and alkaline nature of alluvial soil. The data consist of 195 samples (n=195 taken from the entire district. Samples have been collected from March, 2014 to March, 2015 and experimented in the laboratory. Theoretically PH value is limited within 0–14. Experiment result exemplifies the highest value 8.5 found in Khandaghosh block whereas lowest value is 4.5 and the samples which result in lowest value are gathered from 4 different blocks like Manteswar, Burdwan - II, Barabani and Salanpur.

  7. Is high-intensity interval cycling feasible and more beneficial than continuous cycling for knee osteoarthritic patients? Results of a randomised control feasibility trial

    Directory of Open Access Journals (Sweden)

    Justin W. Keogh

    2018-05-01

    Full Text Available Background Knee osteoarthritis (OA patients often suffer joint pain and stiffness, which contributes to negative changes in body composition, strength, physical performance (function, physical activity and health-related quality of life. To reduce these symptoms and side effects of knee OA, moderate-intensity continuous training (MICT cycling is often recommended. While resistance training is considered the optimal form of training to improve sarcopenic outcomes, it imposes higher joint loads and requires supervision, either initially or continuously by trained exercise professionals. Therefore, this pilot study sought to gain some insight into the feasibility and potential benefits of high-intensity interval training (HIIT cycling as an alternative exercise option to MICT cycling for individuals with knee OA. Methods Twenty-seven middle-aged and older adults with knee OA were randomly allocated to either MICT or HIIT, with both programs involving four unsupervised home-based cycling sessions (∼25 min per session each week for eight weeks. Feasibility was assessed by enrolment rate, withdrawal rate, exercise adherence and number of adverse effects. Efficacy was assessed by health-related quality of life (Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC and Lequesne index, physical function (Timed Up and Go (TUG, Sit to Stand (STS and preferred gait speed and body composition (body mass, BMI, body fat percentage and muscle mass. Results Twenty-seven of the interested 50 potential participants (54% enrolled in the study, with 17 of the 27 participants completing the trial (withdrawal rate of 37%; with the primary withdrawal reasons being unrelated injuries or illness or family related issues. Of the 17 participants who completed the trial, exercise adherence was very high (HIIT 94%; MICT 88%. While only three individuals (one in the MICT and two in the HIIT group reported adverse events, a total of 28 adverse events were

  8. Development of a common priority list of pharmaceuticals relevant for the water cycle

    NARCIS (Netherlands)

    de Voogt, P.; Janex-Habibi, M.-L.; Sacher, F.; Puijker, L.; Mons, M.

    2009-01-01

    Pharmaceutically active compounds (PhACs), including prescription drugs, over-the-counter medications, drugs used in hospitals and veterinary drugs, have been found throughout the water cycle. A desk study was initiated by the Global Water Research Coalition to consolidate a uniform selection of

  9. Effect of two mouthwashes on salivary ph.

    Science.gov (United States)

    Belardinelli, Paola A; Morelatto, Rosana A; Benavidez, Tomás E; Baruzzi, Ana M; López de Blanc, Silvia A

    2014-01-01

    To analyze the effect of two mouthwashes on salivary pH and correlate it with age, buffer capacity and saliva flow rate in healthy volunteers, a crossover phase IV clinical study involving three age-based groups was designed. Two commercial mouthwashes (MW), Cool Mint ListerineR (MWa) and Periobacter R (MWb) were used. The unstimulated saliva of each individual was first characterized by measuring flow rate, pH, and buffer capacity. Salivary pH was evaluated before rinsing with a given MW, immediately after rinsing, 5 minutes later, and then every 10 min (at 15, 25, 35 min) until the baseline pH was recovered. Paired t-test, ANOVA with a randomized block design, and Pearson correlation tests were used. Averages were 0.63 mL/min, 7.06, and 0.87 for flow rate, pH, and buffer capacity, respectively. An immediate significant increase in salivary pH was observed after rinsing, reaching average values of 7.24 (MWb) and 7.30 (MWa), which declined to an almost stable value 15 minutes. The great increase in salivary pH, after MW use shows that saliva is a dynamic system, and that the organism is capable of responding to a stimulus with changes in its composition. It is thus evident that pH of the external agent alone is not a good indicator for its erosive potential because biological systems tend to neutralize it. The results of this study enhance the importance of in vivo measurements and reinforce the concept of the protective action of saliva.

  10. Acidic digestion in a teleost: postprandial and circadian pattern of gastric pH, pepsin activity, and pepsinogen and proton pump mRNAs expression.

    Science.gov (United States)

    Yúfera, Manuel; Moyano, Francisco J; Astola, Antonio; Pousão-Ferreira, Pedro; Martínez-Rodríguez, Gonzalo

    2012-01-01

    Two different modes for regulation of stomach acid secretion have been described in vertebrates. Some species exhibit a continuous acid secretion maintaining a low gastric pH during fasting. Others, as some teleosts, maintain a neutral gastric pH during fasting while the hydrochloric acid is released only after the ingestion of a meal. Those different patterns seem to be closely related to specific feeding habits. However, our recent observations suggest that this acidification pattern could be modified by changes in daily feeding frequency and time schedule. The aim of this study was to advance in understanding the regulation mechanisms of stomach digestion and pattern of acid secretion in teleost fish. We have examined the postprandial pattern of gastric pH, pepsin activity, and mRNA expression for pepsinogen and proton pump in white seabream juveniles maintained under a light/dark 12/12 hours cycle and receiving only one morning meal. The pepsin activity was analyzed according to the standard protocol buffering at pH 2 and using the actual pH measured in the stomach. The results show how the enzyme precursor is permanently available while the hydrochloric acid, which activates the zymogen fraction, is secreted just after the ingestion of food. Results also reveal that analytical protocol at pH 2 notably overestimates true pepsin activity in fish stomach. The expression of the mRNA encoding pepsinogen and proton pump exhibited almost parallel patterns, with notable increases during the darkness period and sharp decreases just before the morning meal. These results indicate that white seabream uses the resting hours for recovering the mRNA stock that will be quickly used during the feeding process. Our data clearly shows that both daily illumination pattern and feeding time are involved at different level in the regulation of the secretion of digestive juices.

  11. Acidic digestion in a teleost: postprandial and circadian pattern of gastric pH, pepsin activity, and pepsinogen and proton pump mRNAs expression.

    Directory of Open Access Journals (Sweden)

    Manuel Yúfera

    Full Text Available Two different modes for regulation of stomach acid secretion have been described in vertebrates. Some species exhibit a continuous acid secretion maintaining a low gastric pH during fasting. Others, as some teleosts, maintain a neutral gastric pH during fasting while the hydrochloric acid is released only after the ingestion of a meal. Those different patterns seem to be closely related to specific feeding habits. However, our recent observations suggest that this acidification pattern could be modified by changes in daily feeding frequency and time schedule. The aim of this study was to advance in understanding the regulation mechanisms of stomach digestion and pattern of acid secretion in teleost fish. We have examined the postprandial pattern of gastric pH, pepsin activity, and mRNA expression for pepsinogen and proton pump in white seabream juveniles maintained under a light/dark 12/12 hours cycle and receiving only one morning meal. The pepsin activity was analyzed according to the standard protocol buffering at pH 2 and using the actual pH measured in the stomach. The results show how the enzyme precursor is permanently available while the hydrochloric acid, which activates the zymogen fraction, is secreted just after the ingestion of food. Results also reveal that analytical protocol at pH 2 notably overestimates true pepsin activity in fish stomach. The expression of the mRNA encoding pepsinogen and proton pump exhibited almost parallel patterns, with notable increases during the darkness period and sharp decreases just before the morning meal. These results indicate that white seabream uses the resting hours for recovering the mRNA stock that will be quickly used during the feeding process. Our data clearly shows that both daily illumination pattern and feeding time are involved at different level in the regulation of the secretion of digestive juices.

  12. Observing Physical and Biological Drivers of pH and O2 in a Seasonal Ice Zone in the Ross Sea Using Profiling Float Data

    Science.gov (United States)

    Briggs, E.; Martz, T. R.; Talley, L. D.; Mazloff, M. R.

    2015-12-01

    Ice cover has strong influence over gas exchange, vertical stability, and biological production which are critical to understanding the Southern Ocean's central role in oceanic biogeochemical cycling and heat and carbon uptake under a changing climate. However the relative influence of physical versus biological processes in this hard-to-study region is poorly understood due to limited observations. Here we present new findings from a profiling float equipped with biogeochemical sensors in the seasonal ice zone of the Ross Sea capturing, for the first time, under-ice pH profile data over a two year timespan from 2014 to the present. The relative influence of physical (e.g. vertical mixing and air-sea gas exchange) and biological (e.g. production and respiration) drivers of pH and O2 within the mixed layer are explored during the phases of ice formation, ice cover, and ice melt over the two seasonal cycles. During the austral fall just prior to and during ice formation, O2 increases as expected due to surface-layer undersaturation and enhanced gas exchange. A small increase in pH is also observed during this phase, but without a biological signal in accompanying profiling float chlorophyll data, which goes against common reasoning from both a biological and physical standpoint. During the phase of ice cover, gas exchange is inhibited and a clear respiration signal is observed in pH and O2 data from which respiration rates are calculated. In the austral spring, ice melt gives rise to substantial ice edge phytoplankton blooms indicated by O2 supersaturation and corresponding increase in pH and large chlorophyll signal. The influence of the duration of ice cover and mixed layer depth on the magnitude of the ice edge blooms is explored between the two seasonal cycles.

  13. KOH concentration effect on the cycle life of nickel-hydrogen cells. IV - Results of failure analysis

    Science.gov (United States)

    Lim, H. S.; Verzwyvelt, S. A.

    1990-01-01

    Potassium hydroxide concentration effects on the cycle life of a Ni/H2 cell have been studied by carrying out a cycle life test on ten Ni/H2 boiler plate cells which contain electrolytes of various KOH concentrations. Failure analyses of these cells were carried out after completion of the life test, which accumulated up to 40,000 cycles at an 80-percent depth of discharge over a period of 3.7 years. These failure analyses included studies on changes of electrical characteristics of test cells, and component analyses after disassembly of the cell. The component analyses included visual inspections, dimensional changes, capacity measurements of nickel electrodes, scanning electron microscopy, surface area measurements, and chemical analyses. Results have indicated that failure mode and change in the nickel electrode varied as the concentration was varied, especially when the concentration was changed from 31 percent or higher to 26 percent or lower.

  14. Spontaneous formation of small unilamellar vesicles by pH jump: A pH gradient across the bilayer membrane as the driving force

    International Nuclear Information System (INIS)

    Hauser, H.; Mantsch, H.H.; Casal, H.L.

    1990-01-01

    31 P NMR and infrared spectroscopic methods have been used to study the formation of small unilamellar vesicles by the pH-jump method. It is shown that increasing the pH of different lamellar phospholipid dispersions (phosphatidic acids and phosphatidylserines) induces a pH gradient. This pH gradient is estimated to be 4 ± 1 pH units, and its direction is such that the inner monolayer of the vesicles is at lower pH. There is spectroscopic evidence for tighter packing of the lipid hydrocarbon chains in the inner monolayer, probably due to the constraints imposed by the high curvature of the small vesicles formed. These results are discussed in terms of the driving force of the spontaneous vesiculation

  15. Life-cycle studies of biodiesel in Europe: A review addressing the variability of results and modeling issues

    International Nuclear Information System (INIS)

    Malca, Joao; Freire, Fausto

    2011-01-01

    Renewable energy sources, and particularly biofuels, are being promoted as possible solutions to address global warming and the depletion of petroleum resources. Nevertheless, significant disagreement and controversies exist regarding the actual benefits of biofuels displacing fossil fuels, as shown by a large number of life-cycle studies that have varying and sometimes contradictory conclusions. This article presents a comprehensive review of life-cycle studies of biodiesel in Europe. Studies have been compared in terms of nonrenewable primary energy requirement and GHG intensity of biodiesel. Recently published studies negate the definite and deterministic advantages for biodiesel presented in former studies. A high variability of results, particularly for biodiesel GHG intensity, with emissions ranging from 15 to 170 gCO 2 eq MJ f -1 has been observed. A detailed assessment of relevant aspects, including major assumptions, modeling choices and results, has been performed. The main causes for this high variability have been investigated, with emphasis on modeling choices. Key issues found are treatment of co-product and land use modeling, including high uncertainty associated with N 2 O and carbon emissions from cultivated soil. Furthermore, a direct correlation between how soil emissions were modeled and increasing values for calculated GHG emission has been found. A robust biodiesel life-cycle modeling has been implemented and the main sources of uncertainty have been investigated to show how uncertainty can be addressed to improve the transparency and reliability of results. Recommendations for further research work concerning the improvement of biofuel life cycle modeling are also presented. (author)

  16. The impact of pH inhomogeneities on CHO cell physiology and fed-batch process performance - two-compartment scale-down modelling and intracellular pH excursion.

    Science.gov (United States)

    Brunner, Matthias; Braun, Philipp; Doppler, Philipp; Posch, Christoph; Behrens, Dirk; Herwig, Christoph; Fricke, Jens

    2017-07-01

    Due to high mixing times and base addition from top of the vessel, pH inhomogeneities are most likely to occur during large-scale mammalian processes. The goal of this study was to set-up a scale-down model of a 10-12 m 3 stirred tank bioreactor and to investigate the effect of pH perturbations on CHO cell physiology and process performance. Short-term changes in extracellular pH are hypothesized to affect intracellular pH and thus cell physiology. Therefore, batch fermentations, including pH shifts to 9.0 and 7.8, in regular one-compartment systems are conducted. The short-term adaption of the cells intracellular pH are showed an immediate increase due to elevated extracellular pH. With this basis of fundamental knowledge, a two-compartment system is established which is capable of simulating defined pH inhomogeneities. In contrast to state-of-the-art literature, the scale-down model is included parameters (e.g. volume of the inhomogeneous zone) as they might occur during large-scale processes. pH inhomogeneity studies in the two-compartment system are performed with simulation of temporary pH zones of pH 9.0. The specific growth rate especially during the exponential growth phase is strongly affected resulting in a decreased maximum viable cell density and final product titer. The gathered results indicate that even short-term exposure of cells to elevated pH values during large-scale processes can affect cell physiology and overall process performance. In particular, it could be shown for the first time that pH perturbations, which might occur during the early process phase, have to be considered in scale-down models of mammalian processes. Copyright © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Variation in the carbon cycle of the Sevastopol Bay (Black Sea)

    Science.gov (United States)

    Orekhova, N. A.; Konovalov, S. K.

    2018-01-01

    Continuous increase in CO2 inventory in the ocean results in dramatic changes in marine biogeochemistry, e.g. acidification. That is why temporal and spatial variabilities in atmospheric pCO2 and dissolved inorganic carbon, including CO2, pH and alkalinity in water, as well as organic and inorganic carbon in bottom sediments have to be studied together making possible to resolve the key features of the carbon cycle transformation. A 30% increase of pCO2 in the Sevastopol Bay for 2008 - 2016 evidences changes in the DIC components ratios and a significant decrease in the ability to absorb atmospheric CO2 by surface waters. High organic carbon content in the bottom sediments and predominance of organic carbon production in the biological pump at inner parts of the bay reveal ongoing transformation of the carbon cycle. This has negative consequences for recreation, social and economic potentials of the Sevastopol region.

  18. Correlação entre Testes para Avaliação da Vitalidade Fetal, pH da Artéria Umbilical e os Resultados Neonatais em Gestações de Alto Risco Correlation between the Assessment of Fetal Well-being, Umbilical Artery pH at Birth and the Neonatal Results in High-risk Pregnancies

    Directory of Open Access Journals (Sweden)

    Rossana Pulcineli Vieira Francisco

    2000-09-01

    Full Text Available Objetivos: analisar a relação entre valores de pH no nascimento, testes de vitalidade fetal e resultados neonatais. Métodos: foram incluídas 1346 pacientes com gestação de alto risco atendidas no Setor de Vitalidade Fetal do HCFMUSP. Para estudo do bem-estar fetal foram realizados exames de cardiotocografia, perfil biofísico fetal e índice de líquido amniótico. Após o parto foram obtidos os seguintes parâmetros dos recém-nascidos: idade gestacional no parto, sexo e peso dos recém-nascidos, índices de Apgar de 1º e 5º minutos, pH da artéria umbilical no nascimento e a ocorrência de óbito neonatal. Para estudo destes resultados neonatais, os casos foram divididos em quatro grupos: G1 (pH ou = 7,20. Resultados: a cardiotocografia anormal relacionou-se com valores de pH inferiores a 7,20 (p = 0,001. Resultados anormais do perfil biofísico fetal (Purpose: to analyze the relationship between the values of pH at birth, fetal surveillance examinatios and neonatal results. Methods: one thousand, three hundred and forty-six high-risk pregnancies were evaluated at the Fetal Surveillance Unit. The assessment of fetal well-being included cardiotocography, fetal biophysical profile and amniotic fluid index. After birth, the perinatal results (gestational age at birth, birth weight, Apgar scores at 1st and 5th minutes, umbilical cord pH at birth were collected. To study the results, the patients were divided into four groups: G1 (pH or = 7.20. Results: the abnormal patterns of cardiotocography were associated with pH at birth inferior to 7.20 (p = 0.001. Abnormal results of the fetal biophysical profile (<=4 were related to decrease in pH values at birth (p<0.001. The adverse neonatal outcomes were associated with acidosis at birth, and they were selected to be analyzed by the logistic regression model, showing that the odds ratio of each adverse neonatal outcome increases significantly when the values of pH at birth decrease. Conclusions

  19. Measurement of brain pH with positron emission tomography

    International Nuclear Information System (INIS)

    Buxton, R.B.; Alpert, N.M.; Ackerman, R.H.; Wechsler, L.R.; Elmaleh, D.R.; Correia, J.A.

    1985-01-01

    With positron emission tomography (PET) it is now possible to measure local brain pH noninvasively in humans. The application of PET to the determination of pH is relatively new, so only a handful of papers on the subject have appeared in print. This chapter reviews the current strategies for measuring brain pH with PET, discuss methodological problems, and present initial results

  20. Foliar pH as a new plant trati: van it explain variation in foliar chemistry and carbon cycling processes among subarctiv plant species and types?

    NARCIS (Netherlands)

    Cornelissen, J.H.C.; Quested, H.M.; van Logtestijn, R.S.P; Perez-Harguindeguy, N.; Gwynn-Jones, D.; Diaz, S.; Callaghan, T.V.; Press, M.C.; Aerts, R.

    2006-01-01

    Plant traits have become popular as predictors of interspecific variation in important ecosystem properties and processes. Here we introduce foliar pH as a possible new plant trait, and tested whether (1) green leaf pH or leaf litter pH correlates with biochemical and structural foliar traits that

  1. Synthesis of Cross-Linked Polymeric Micelle pH Nanosensors

    DEFF Research Database (Denmark)

    Ek, Pramod Kumar; Jølck, Rasmus Irming; Andresen, Thomas Lars

    2015-01-01

    The design flexibility that polymeric micelles offer in the fabrication of optical nanosensors for ratiometric pH measurements is investigated. pH nanosensors based on polymeric micelles are synthesized either by a mixed-micellization approach or by a postmicelle modification strategy. In the mixed......-micellization approach, self-assembly of functionalized unimers followed by shell cross-linking by copper-catalyzed azide-alkyne cycloaddition (CuAAC) results in stabilized cRGD-functionalized micelle pH nanosensors. In the postmicelle modification strategy, simultaneous cross-linking and fluorophore conjugation...... at the micelle shell using CuAAC results in a stabilized micelle pH nanosensor. Compared to the postmicelle modification strategy, the mixed-micellization approach increases the control of the overall composition of the nanosensors.Both approaches provide stable nanosensors with similar pKa profiles and thereby...

  2. PhEDEx Data Service

    International Nuclear Information System (INIS)

    Egeland, Ricky; Wildish, Tony; Huang, Chih-Hao

    2010-01-01

    The PhEDEx Data Service provides access to information from the central PhEDEx database, as well as certificate-authenticated managerial operations such as requesting the transfer or deletion of data. The Data Service is integrated with the 'SiteDB' service for fine-grained access control, providing a safe and secure environment for operations. A plug-in architecture allows server-side modules to be developed rapidly and easily by anyone familiar with the schema, and can automatically return the data in a variety of formats for use by different client technologies. Using HTTP access via the Data Service instead of direct database connections makes it possible to build monitoring web-pages with complex drill-down operations, suitable for debugging or presentation from many aspects. This will form the basis of the new PhEDEx website in the near future, as well as providing access to PhEDEx information and certificate-authenticated services for other CMS dataflow and workflow management tools such as CRAB, WMCore, DBS and the dashboard. A PhEDEx command-line client tool provides one-stop access to all the functions of the PhEDEx Data Service interactively, for use in simple scripts that do not access the service directly. The client tool provides certificate-authenticated access to managerial functions, so all the functions of the PhEDEx Data Service are available to it. The tool can be expanded by plug-ins which can combine or extend the client-side manipulation of data from the Data Service, providing a powerful environment for manipulating data within PhEDEx.

  3. Orbit transfer vehicle advanced expander cycle engine point design study. Volume 2: Study results

    Science.gov (United States)

    Diem, H. G.

    1980-01-01

    The design characteristics of the baseline engine configuration of the advanced expander cycle engine are described. Several aspects of engine optimization are considered which directly impact the design of the baseline thrust chamber. Four major areas of the power cycle optimization are emphasized: main turbine arrangement; cycle engine source; high pressure pump design; and boost pump drive.

  4. Yogurt made from milk heated at different pH values.

    Science.gov (United States)

    Ozcan, Tulay; Horne, David S; Lucey, John A

    2015-10-01

    Milk for yogurt manufacture is subjected to high heat treatment to denature whey proteins. Low milk pH values (≤ 6.5) at heating result in most denatured whey proteins becoming associated with casein micelles, whereas high milk pH values (≥ 7.0) at heating result in the formation of mostly soluble (nonmicellar) denatured whey protein complexes. There are conflicting reports on the relative importance of soluble and casein-bound whey protein aggregates on the properties of acid gels. Prior studies investigating the effect of pH of milk at heating used model gels in which milk was acidified by glucono-δ-lactone; in this study, we prepared yogurt gels using commercial starter cultures. Model acid gels can have very different texture and physical properties from those made by fermentation with starter cultures. In this study, we investigated the effects of different pH values of milk at heating on the rheological, light backscatter, and microstructural properties of yogurt gels. Reconstituted skim milk was adjusted to pH values 6.2, 6.7, and 7.2 and heated at 85°C for 30 min. A portion of the heated milk samples was readjusted back to pH 6.7 after heating. Milks were inoculated with 3% (wt/wt) yogurt starter culture and incubated at 40°C until pH 4.6. Gel formation was monitored using dynamic oscillatory rheology, and parameters measured included the storage modulus (G') and loss tangent (LT) values. Light-backscattering properties, such as the backscatter ratio (R) and the first derivative of light backscatter ratio (R'), were also monitored during fermentation. Fluorescence microscopy was used to observe gel microstructure. The G' values at pH 4.6 were highest in gels made from milk heated at pH 6.7 and lowest in milk heated at pH 6.2, with or without pH adjustment after heating. The G' values at pH 4.6 were lower in samples after adjustment back to pH 6.7 after heating. No maximum in the LT parameter was observed during gelation for yogurts made from milk

  5. pH dependent polymeric micelle adsorption

    Energy Technology Data Exchange (ETDEWEB)

    McLean, S C; Gee, M L [The University of Melbourne, VIC (Australia). School of Chemistry

    2003-07-01

    Full text: Poly(2-vinylpyridine)-poly(ethylene oxide) (P2VP-PEO) shows potential as a possible drug delivery system for anti-tumour drugs since it forms pH dependent polymeric micelles. Hence to better understand the adsorption behaviour of this polymer we have studied the interaction forces between layers of P2VP-PEO adsorbed onto silica as a function of solution pH using an Atomic Force Microscope (AFM). When P2VP-PEO is initially adsorbed above the pKa of the P2VP block, P2VP-PEO adsorbs from solution as micelles that exist as either partially collapsed- or a hemi-micelles at the silica surface. Below the pKa of P2VP, the P2VP-PEO adsorbs as unimers, forming a compact layer with little looping and tailing into solution. When initial adsorption of P2VP-PEO is in the form of unimers, any driving force to self-assembly of the now charge neutral polymer is kinetically hindered. Hence, after initial adsorption at pH 3.6, a subsequent increase in pH to 6.6 results in a slow surface restructuring towards self-assembly and equilibrium. When the pH is increased from pH 6.6 to 9.7 there is a continuation of the evolution of the system to its equilibrium position during which the adsorbed P2VP-PEO unimers continue to 'unravel' from the surface, extending away from it, towards eventual complete surface self-assembly.

  6. Glacial cycles

    DEFF Research Database (Denmark)

    Kaufmann, R. K.; Juselius, Katarina

    We use a statistical model, the cointegrated vector autoregressive model, to assess the degree to which variations in Earth's orbit and endogenous climate dynamics can be used to simulate glacial cycles during the late Quaternary (390 kyr-present). To do so, we estimate models of varying complexity...... and compare the accuracy of their in-sample simulations. Results indicate that strong statistical associations between endogenous climate variables are not enough for statistical models to reproduce glacial cycles. Rather, changes in solar insolation associated with changes in Earth's orbit are needed...... to simulate glacial cycles accurately. Also, results suggest that non-linear 10 dynamics, threshold effects, and/or free oscillations may not play an overriding role in glacial cycles....

  7. The Final Frontier of pH and the Undiscovered Country Beyond

    Science.gov (United States)

    Bal, Wojciech; Kurowska, Ewa; Maret, Wolfgang

    2012-01-01

    The comparison of volumes of cells and subcellular structures with the pH values reported for them leads to a conflict with the definition of the pH scale. The pH scale is based on the ionic product of water, K w = [H+]×[OH−].We used K w [in a reversed way] to calculate the number of undissociated H2O molecules required by this equilibrium constant to yield at least one of its daughter ions, H+ or OH− at a given pH. In this way we obtained a formula that relates pH to the minimal volume VpH required to provide a physical meaning to K w, (where N A is Avogadro’s number). For example, at pH 7 (neutral at 25°C) VpH = 16.6 aL. Any deviation from neutral pH results in a larger VpH value. Our results indicate that many subcellular structures, including coated vesicles and lysosomes, are too small to contain free H+ ions at equilibrium, thus the definition of pH based on K w is no longer valid. Larger subcellular structures, such as mitochondria, apparently contain only a few free H+ ions. These results indicate that pH fails to describe intracellular conditions, and that water appears to be dissociated too weakly to provide free H+ ions as a general source for biochemical reactions. Consequences of this finding are discussed. PMID:23049874

  8. Objective determination of pH thresholds in the analysis of 24 h ambulatory oesophageal pH monitoring

    NARCIS (Netherlands)

    Weusten, B. L.; Roelofs, J. M.; Akkermans, L. M.; vanBerge-Henegouwen, G. P.; Smout, A. J.

    1996-01-01

    In 24 h oesophageal pH monitoring, pH 4 is widely but arbitrarily used as the threshold between reflux and non-reflux pH values. The aim of the study was to define pH thresholds objectively, based on Gaussian curve fitting of pH frequency distributions. Single-channel 24 h oesophageal pH monitoring

  9. Indications of 24-h esophageal pH monitoring, capsule pH monitoring, combined pH monitoring with multichannel impedance, esophageal manometry, radiology and scintigraphy in gastroesophageal reflux disease?

    Science.gov (United States)

    Vardar, Rukiye; Keskin, Muharrem

    2017-12-01

    Ambulatory esophageal pH monitoring is an essential method in patients exhibiting signs of non-erosive reflux disease (NERD) to make an objective diagnosis. Intra-esophageal pH monitoring is important in patients who are non-responsive to medications and in those with extraesophageal symptoms, particularly in NERD, before surgical interventions. With the help of the wireless capsule pH monitoring, measurements can be made under more physiological conditions as well as longer recordings can be performed because the investigation can be better tolerated by patients. Ambulatory esophageal pH monitoring can be detected within normal limits in 17%-31.4% of the patients with endoscopic esophagitis; therefore, normal pH monitoring cannot exclude the diagnosis of gastroesophageal reflux disease (GERD). Multi-channel intraluminal impedance pH (MII-pH) technology have been developed and currently the most sensitive tool to evaluate patients with both typical and atypical reflux symptoms. The sensitivity of a pH catheter test is 58% for the detection of acid reflux compared with MII-pH monitoring; further, its sensitivity is 28% for the detection of weak acid reflux compared with MII-pH monitoring. By adding impedance to pH catheter in patients with reflux symptoms, particularly in those receiving PPIs, it has been demonstrated that higher rates of diagnoses and symptom analyses can be obtained than those using only pH catheter. Esophageal manometry is used in the evaluation of patients with functional dysphagia and unexplained noncardiac chest pain and prior to antireflux surgery. The use of esophageal manometry is suitable for the detection of esophageal motor patterns and extreme motor abnormalities (e.g., achalasia and extreme hypomotility). Esophageal manometry and ambulatory pH monitoring are often used in assessments prior to laparoscopic antireflux surgery and in patients with reflux symptoms refractory to medical treatment. Although the esophageal motility is

  10. 31P NMR studies of pH homeostasis in intact adult Fasciola hepatica

    NARCIS (Netherlands)

    Tielens, A.G.M.; Nicolaij, K.; Bergh, van S.G.

    1982-01-01

    31P NMR was used to measure the intracellular pH in live adult Fasciola hepatica. The results demonstrate that at external pH values above 7.0, pH homeostasis keeps the intracellular pH at 7.0. At external pH values below 7.0 the intracellular pH is less strictly regulated.

  11. Evaluating Nanoparticle Sensor Design for Intracellular pH Measurements

    DEFF Research Database (Denmark)

    Benjaminsen, Rikke Vicki; Sun, Honghao; Henriksen, Jonas Rosager

    2011-01-01

    Particle-based nanosensors have over the last decade been designed for optical fluorescent-based ratiometric measurements of pH in living cells. However, quantitative and time-resolved intracellular measurements of pH in endosomes and lysosomes using particle nanosensors is challenging...... and there is a need to improve measurement methodology. In the present paper, we have successfully carried out time resolved pH measurements in endosomes and lyosomes in living cells using nanoparticle sensors and show the importance of sensor choice for successful quantification. We have studied two nanoparticle...... quantification of pH is an unfortunate result when measuring pH too close to the limit of the sensitive range of the sensors. Triple-labeled nanosensors with a pH measurement range of 3.2-7.0, which was synthesized by adding two pH-sensitive fluorophores with different pKa to each sensor, seem to be a solution...

  12. A comprehensive assessment of the life cycle energy demand of passive houses

    International Nuclear Information System (INIS)

    Stephan, André; Crawford, Robert H.; Myttenaere, Kristel de

    2013-01-01

    Highlights: • The life cycle energy demand of a passive house (PH) is measured over 100 years. • Embodied, operational and user transport energy demand are considered. • Embodied energy represents the highest energy consumption in all variations. • A PH might not save energy compared to a standard house. • A poorly insulated city apartment can use less energy than a best case suburban PH. - Abstract: Certifications such as the Passive House aim to reduce the final space heating energy demand of residential buildings. The latter are responsible for a significant share of final energy consumption in Europe of which nearly 70% is associated with space conditioning, notably heating. The improvement of the energy efficiency of residential buildings, in terms of space heating, can therefore reduce their total energy demand. However, most certifications totally overlook other energy requirements associated with residential buildings. Studies on passive houses do not take into consideration the embodied energy required to manufacture the building materials, especially the large amount of insulation required to achieve high operational efficiencies. At an urban scale, most passive houses are single family detached houses located in low density suburbs with a high car usage, resulting in considerable transport related energy demand. This paper analyses the total life cycle energy demand of a typical Belgian passive house, comprising embodied, operational and transport energy. It relies on a comprehensive technique developed by Stephan et al. [1] and conducts a parametric analysis as well as a comparison to alternative building types. Results show that current building energy efficiency certifications might not ensure a lower energy demand and can, paradoxically result in an increased energy consumption because of their limited scope. More comprehensive system boundaries should be used to make sure that net energy savings do occur. The embodied energy of passive

  13. Resistance of Streptococcus bovis to acetic acid at low pH: Relationship between intracellular pH and anion accumulation

    Energy Technology Data Exchange (ETDEWEB)

    Russell, J.B. (Cornell Univ., Ithaca, NY (USA))

    1991-01-01

    Streptococcus bovis JB1, an acid-tolerant ruminal bacterium, was able to grown at pHs from 6.7 to 4.5, and 100 mM acetate had little effect on growth rate or proton motive force across the cell membrane. When S. bovis was grown in glucose-limited chemostats at pH 5.2, the addition of sodium acetate (as much as 100 mM) had little effect on the production of bacterial protein. At higher concentrations of sodium acetate (100 to 360 mM), production of bacterial protein declined, but this decrease could largely be explained by a shift in fermentation products (acetate, formate, and ethanol production to lactate production) and a decline in ATP production (3 ATP per glucose versus 2 ATP per glucose). Y{sub ATP} (grams of cells per mole at ATP) was not decreased significantly even by high concentrations of acetate. Cultures supplemented with 100 mM sodium acetate took up ({sup 14}C)acetate and ({sup 14}C)benzoate in accordance with the Henderson-Hasselbalch equation and gave similar estimates of intracellular pH. As the extracellular pH declined, S. bovis allowed its intracellular pH to decrease and maintained a relatively constant pH gradient across the cell membrane (0.9 unit). The decrease in intracellular pH prevented S. bovis from accumulating large amounts of acetate anion. On the basis of these results it did not appear that acetate was acting as an uncoupler. The sensitivity of other bacteria to volatile fatty acids at low pH is explained most easily by a high transmembrane pH gradient and anion accumulation.

  14. Resistance of Streptococcus bovis to acetic acid at low pH: Relationship between intracellular pH and anion accumulation

    International Nuclear Information System (INIS)

    Russell, J.B.

    1991-01-01

    Streptococcus bovis JB1, an acid-tolerant ruminal bacterium, was able to grown at pHs from 6.7 to 4.5, and 100 mM acetate had little effect on growth rate or proton motive force across the cell membrane. When S. bovis was grown in glucose-limited chemostats at pH 5.2, the addition of sodium acetate (as much as 100 mM) had little effect on the production of bacterial protein. At higher concentrations of sodium acetate (100 to 360 mM), production of bacterial protein declined, but this decrease could largely be explained by a shift in fermentation products (acetate, formate, and ethanol production to lactate production) and a decline in ATP production (3 ATP per glucose versus 2 ATP per glucose). Y ATP (grams of cells per mole at ATP) was not decreased significantly even by high concentrations of acetate. Cultures supplemented with 100 mM sodium acetate took up [ 14 C]acetate and [ 14 C]benzoate in accordance with the Henderson-Hasselbalch equation and gave similar estimates of intracellular pH. As the extracellular pH declined, S. bovis allowed its intracellular pH to decrease and maintained a relatively constant pH gradient across the cell membrane (0.9 unit). The decrease in intracellular pH prevented S. bovis from accumulating large amounts of acetate anion. On the basis of these results it did not appear that acetate was acting as an uncoupler. The sensitivity of other bacteria to volatile fatty acids at low pH is explained most easily by a high transmembrane pH gradient and anion accumulation

  15. Low pH Springs - A Natural Laboratory for Ocean Acidification

    Science.gov (United States)

    Derse, E.; Rebolledo-Vieyra, M.; Potts, D. C.; Paytan, A.

    2009-12-01

    Recent increases in atmospheric carbon dioxide of 40% above pre-industrial levels has resulted in rising aqueous CO2 concentrations that lower the pH of the oceans. Currently, the surface ocean has an average pH between 8.1 and 8.2: it is estimated that over the next 100 years this value will decrease by ~0.4 pH units. Previous studies have highlighted the negative impacts that changes in pH (and the resulting CaCO3 saturation state) have on marine organisms; however, to date, very little is known about the long-term impacts of ocean acidification on ecosystems as a whole. The Yucatán Peninsula of Quintana Roo, Mexico, represents an ecosystem where naturally low pH groundwater (7.25-8.07) has been discharging offshore at highly localized points (called ojos) since the last deglaciation. We present preliminary chemical and biological data on a selection of ojos from lagoon sites in Puerto Morelos, Mexico. We address the potential long-term implications of low pH waters on marine ecosystems.

  16. Water pH and temperature in Lake Biwa from MBT'/CBT indices during the last 282 000 years

    Science.gov (United States)

    Ajioka, T.; Yamamoto, M.; Takemura, K.; Hayashida, A.

    2014-03-01

    We generated a 282 000-year record of water pH and temperature in Lake Biwa, central Japan, by analysing the methylation index (MBT') and cyclisation ratio (CBT) of branched tetraethers in sediments from piston and borehole cores to understand the responses of precipitation and air temperature in central Japan to the East Asian monsoon variability on the orbital timescale. Because water pH in Lake Biwa is determined by phosphorus input driven by precipitation, the record of water pH should indicate changes in summer precipitation in central Japan. The estimated pH showed significant periodicity at 19 and 23 ka (precession) and at 41 ka (obliquity). The variation in the estimated pH agrees with variation in the pollen temperature index. This indicates synchronous variation in summer air temperature and precipitation in central Japan, which contradicts the conclusions of previous studies. The variation in estimated pH was also synchronous with the variation of oxygen isotopes in stalagmites in China, suggesting that East Asian summer monsoon precipitation was governed by Northern Hemisphere summer insolation on orbital timescales. However, the estimated winter temperatures were higher during interglacials and lower during glacials, showing an eccentricity cycle. This suggests that the temperature variation reflected winter monsoon variability.

  17. Diurnal variation of intraoral pH and temperature.

    Science.gov (United States)

    Choi, Jung Eun; Lyons, Karl M; Kieser, Jules A; Waddell, Neil J

    2017-01-01

    The aim of this study was to measure continuously the intraoral pH and temperature of healthy individuals to investigate their diurnal variations. Seventeen participants (mean age, 31±9 years) wore a custom-made intraoral appliance fitted with a pH probe and thermocouple for two sets of 24 h, while carrying out normal daily activities including sleep. The continuous changes in intraoral pH and temperature were captured using a sensor placed on the palatal aspect of the upper central incisors. The collected data were categorised into different status (awake and sleep) and periods (morning, afternoon, evening and night). Both quantitative and qualitative analyses were conducted. The intraoral pH change was found to show a distinctive daily rhythm, showing a 12-h interval between maximum (7.73) and minimum (6.6) pH values. The maximum and minimum values were found to repeat after 24 h. The mean pH over 48 h (two sets of 24 h) was found to be 7.27 (±0.74). There was significant difference found in pH when subjects were awake and asleep and different periods during the day ( P pH. There was a significant difference found in temperature depending on the time of the day, except between morning and afternoon ( P =0.78). Our results showed that there is a distinctive daily, circadian-like pattern in intraoral pH variation over a 24-h period, which has been considered as one of the risk factors in sleep-related dental diseases.

  18. The pH dependency of N-converting enzymatic processes, pathways and microbes: effect on net N2O production

    DEFF Research Database (Denmark)

    Blum, Jan-Michael; Su, Qingxian; Ma, Yunjie

    2018-01-01

    causing steric changes in catalytic sites or proton/electron transfer routes that alter the enzymes' overall activity. Augmenting molecular information with, e.g., nitritation or denitrification rates yields explanations of changes in net N2 O production with pH. Ammonia oxidizing bacteria are of highest...... relevance for N2 O production, while heterotrophic denitrifiers are relevant for N2 O consumption at pH > 7.5. Net N2 O production in N-cycling water engineering systems is predicted to display a 'bell-shaped' curve in the range of pH 6.0-9.0 with a maximum at pH 7.0-7.5. Net N2 O production at acidic p...

  19. The pH changes of artificial saliva after interaction with oral of artificial saliva after interaction with oral micropathogen

    Directory of Open Access Journals (Sweden)

    Basri A. Gani

    2012-12-01

    Full Text Available Backgorund: Saliva contains several protein elements, exocrine proteins and antibodies, such as lactoferrin, sIgA, peroxidase, albumin, polypeptides, and oligopeptides that contribute to the defense of oral mucosa and dental pellicle to prevent infection caused by oral micropathogen, such as Candida albicans, Streptococcus mutans and Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans. Those micropathogens have a role to change salivary pH as an indicator of oral disease activities. Purpose: This study was aimed to analyze the changes of artificial saliva pH after interaction with S. mutans, C. albicans, and A. Actinomycetemcpmitans. Methods: The materials used in this study consist of S. mutans (ATCC 31987, C. albicans (ATCC 10231, A. actinomycetemcomitans (ATTC 702 358, and artificial saliva. To examine the pH changes of artificial saliva, those three microbiotas were cultured and incubated for 24 hours. Results: The results showed that the interactions of S. mutans, C. albicans, and A. actinomycetemcomitans in the artificial saliva can change the salivary on neutral. There were no significant difference with the control treatment salivary pH 4, 5, 6, 8, and 9 (p>0.05. Similarly, there was also no significant difference when those three microorganism interacted each other in the artificial saliva (p<0.05. Conclusion: It can be concluded that the biological activity of S. mutans, C. albicans, and A. actinomycetemcomitans in artificial saliva can change the salivary pH into neutral. It indicates that those microbiotas mutually supported and cooperated in influencing the biological cycle of the oral cavity with salivary pH as an indicator.Latar belakang: Saliva merupakan cairan eksokrin yang mengandung unsur protein dan antibodi seperti sIgA laktoferin peroksidase, albumin, polipeptida dan oligopeptida yang berperan pada pertahanan mukosa rongga mulut dan gigi guna mencegah infeksi oral mikropatogen seperti C. albicans, S. mutans, dan

  20. Effects of Seawater Acidification on the Life Cycle and fitness of Opossum Shrimp Populations

    Science.gov (United States)

    Much of the current concern about ecological effects of ocean acidification focuses on molluscs and coccolithophores because of their importance in the global calcium cycle. However, many other marine organisms are likely to be affected by acidification because of their known ph...

  1. The majority of irregular menstrual cycles in adolescence are ovulatory: results of a prospective study.

    Science.gov (United States)

    Peña, Alexia S; Doherty, Dorota A; Atkinson, Helen C; Hickey, Martha; Norman, Robert J; Hart, Roger

    2018-03-01

    While ovulation is most likely to occur in adolescent girls with regular menstrual cycles, there are limited data on the incidence of ovulation in girls with irregular menstrual cycles in early postmenarcheal years. The aim of the study was to evaluate the presence of ovulation in healthy postmenarcheal girls with irregular menstrual cycles. Prospective cohort study over 12 weeks including 40 healthy postmenarcheal girls recruited from the population-based cohort of adolescents from Western Australian Pregnancy Cohort (Raine) Study with irregular menstrual cycles defined by either menstrual cycles 35 days in duration or cycle length that varied from month to month by >4 days according to menstrual diaries. Ovulation defined by urinary pregnanediol-3α-glucuronide/creatinine measurements higher than three times above minimum value obtained from 12 samples (1 per week). Forty girls (37 Caucasians) with irregular menstrual cycles aged 15.1 (median (IQR) 14.9-15.4) years who were 2.3 (1.9-3.3) years postmenarche were assessed. Urinary pregnanediol-3α-glucuronide/creatinine values identified that 33 girls (82.5%) ovulated during the 3 months of observation and 7 girls had anovulatory cycles. Menstrual diaries collected for a median (IQR) of 159 (137.5-188.2) days showed median minimal and maximum menstrual cycle duration of 24 (11.5-29) and 38.5 (35-48) days, respectively. A large proportion of healthy adolescent girls with irregular menstrual cycles are still ovulating despite irregular and infrequent menses. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  2. Results from low cycle fatigue testing of 316L plate and weld material

    International Nuclear Information System (INIS)

    Kaellstroem, R.; Josefsson, B.; Haag, Y.

    1993-01-01

    Specimens for low cycle fatigue testing from the second heat of the CEC reference 316L plate and from Tungsten Inert Gas (TIG) weld material have been neutron irradiated near room temperature to a displacement dose of approximately 0.3 dpa. The low cycle fatigue testing of both irradiated and unirradiated specimens was performed at 75, 250 and 450 degrees C, and with strain ranges of 0.75, 1.0 and 1.5%. There is no clear effect of the irradiation on low cycle fatigue properties. For the weld material the endurance is shorter than for plate, and the dependences on temperature and strain range are not clear

  3. The PhD by Publication

    Directory of Open Access Journals (Sweden)

    Susi Peacock

    2017-07-01

    Full Text Available Aim/Purpose: The purpose of this work is to develop more nuanced understandings of the PhD by publication, particularly raising awareness of the retrospective PhD by publication. The article aims to contribute to contemporary debates about the differing pathways to the attainment of doctoral study completion and the artifacts submitted for that purpose. It also seeks to support prospective graduate students and supervisors who are embarking upon alternative routes to doctoral accreditation. Background: The PhD is considered the pinnacle of academic study – highly cherished, and replete with deeply held beliefs. In response to changes in job markets, developments in the disciplines, and more varied student cohorts, diverse pathways to completion of this award have emerged, such as the PhD by publication (PhDP. A PhDP may either be prospective or retrospective. For the former, publications are planned and created with their contributions to the PhDP in mind. The retrospective PhD is assembled after some, or most, of the publications have been completed. The artifact submitted for examination in this case consists of a series of peer-reviewed academic papers, books, chapters, or equivalents that have been published or accepted for publication, accompanied by an over-arching narrative. The retrospective route is particularly attractive for professionals who are research-active but lack formal academic accreditation at the highest level. Methodology: This article calls upon a literature review pertaining to the award of PhDP combined with the work of authors who offer their personal experiences of the award. The author also refers to her candidature as a Scottish doctoral student whilst studying for the award of PhD by publication. Contribution: This work raises awareness of the PhDP as a credible and comparable pathway for graduate students. The article focuses upon the retrospective PhDP which, as with all routes to doctoral accreditation, has

  4. Comparative Evaluation of the Effect of Menstruation, Pregnancy and Menopause on Salivary Flow Rate, pH and Gustatory Function.

    Science.gov (United States)

    Saluja, Pulin; Shetty, Vishwaprakash; Dave, Aparna; Arora, Manpreet; Hans, Vibha; Madan, Ajay

    2014-10-01

    There are five situations in a women's life during which hormone fluctuations make them more susceptible to oral health problems - during puberty, at certain points in the monthly menstrual cycle, when using birth control pills, during pregnancy, and at menopause. The present study aimed at evaluating the effect of menstruation, pregnancy and menopause on salivary flow rate, pH and gustatory function. The study was carried out on 120 patients including 30 controls (with normal menstrual cycle of 28 to 30 d) and 90 cases (30 patients within three days of menstruation, 30 pregnant and 30 postmenopausal). Paraffin-stimulated saliva samples were obtained by expectoration to calculate salivary flow rate, pH was measured electrometically and patients were prospectively evaluated for gustatory function. Then, whole mouth taste test was performed in which the quality identification and intensity ratings of taste solutions were measured. No statistically significant difference was found between the groups with respect to salivary flow rate but pH values were significantly lower in post menopausal women (pwomen than intensity of taste perception for other tastes (pwomen reported change in their dietary habits as all of them expressed liking for sweeter food. Reduced salivary flow rate and pH in postmen-opausal women may make them more prone to the occurrence of oral health problems. Also, pregnant and postmenopausal women appeared to have a reduced perception of sucrose, which can alter eating habits, such as intake of more sweet foods whereas no significant difference is observed in taste perception of NaCl, citric acid and quinine hydrochloride between the subjects.

  5. Predicting and measurement of pH of seawater reverse osmosis concentrates

    KAUST Repository

    Waly, Tarek

    2011-10-01

    The pH of seawater reverse osmosis plants (SWRO) is the most influential parameter in determining the degree of supersaturation of CaCO3 in the concentrate stream. For this, the results of pH measurements of the concentrate of a seawater reverse osmosis pilot plant were compared with pH calculations based on the CO2-HCO3 --CO3 2- system equilibrium equations. Results were compared with two commercial software programs from membrane suppliers and also the software package Phreeqc. Results suggest that the real concentrate pH is lower than that of the feed and that none of the used programs was able to predict correctly real pH values. In addition, the effect of incorporating the acidity constant calculated for NaCl medium or seawater medium showed a great influence on the concentrate pH determination. The HCO3 - and CO3 2- equilibrium equation using acidity constants developed for seawater medium was the only method able to predict correctly the concentrate pH. The outcome of this study indicated that the saturation level of the concentrate was lower than previously anticipated. This was confirmed by shutting down the acid and the antiscalants dosing without any signs of scaling over a period of 12 months. © 2011 Elsevier B.V.

  6. Influence of pH on extracellular matrix preservation during lung decellularization.

    Science.gov (United States)

    Tsuchiya, Tomoshi; Balestrini, Jenna L; Mendez, Julio; Calle, Elizabeth A; Zhao, Liping; Niklason, Laura E

    2014-12-01

    The creation of decellularized organs for use in regenerative medicine requires the preservation of the organ extracellular matrix (ECM) as a means to provide critical cues for differentiation and migration of cells that are seeded onto the organ scaffold. The purpose of this study was to assess the influence of varying pH levels on the preservation of key ECM components during the decellularization of rat lungs. Herein, we show that the pH of the 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS)-based decellularization solution influences ECM retention, cell removal, and also the potential for host response upon implantation of acellular lung tissue. The preservation of ECM components, including elastin, fibronectin, and laminin, were better retained in the lower pH conditions that were tested (pH ranges tested: 8, 10, 12); glycosaminoglycans were preserved to a higher extent in the lower pH groups as well. The DNA content following decellularization of the rat lung was inversely correlated with the pH of the decellularization solution. Despite detectible levels of cyotoskeletal proteins and significant residual DNA, tissues decellularized at pH 8 demonstrated the greatest tissue architecture maintenance and the least induction of host response of all acellular conditions. These results highlight the effect of pH on the results obtained by organ decellularization and suggest that altering the pH of the solutions used for decellularization may influence the ability of cells to properly differentiate and home to appropriate locations within the scaffold, based on the preservation of key ECM components and implantation results.

  7. The final frontier of pH and the undiscovered country beyond.

    Directory of Open Access Journals (Sweden)

    Wojciech Bal

    Full Text Available The comparison of volumes of cells and subcellular structures with the pH values reported for them leads to a conflict with the definition of the pH scale. The pH scale is based on the ionic product of water, K(w = [H(+]×[OH(-].We used K(w [in a reversed way] to calculate the number of undissociated H(2O molecules required by this equilibrium constant to yield at least one of its daughter ions, H(+ or OH(- at a given pH. In this way we obtained a formula that relates pH to the minimal volume V(pH required to provide a physical meaning to K(w, V(pH=10(pH-pK(w/2 x 10(pK(w/2/N(A (where N(A is Avogadro's number. For example, at pH 7 (neutral at 25°C V(pH =16.6 aL. Any deviation from neutral pH results in a larger V(pH value. Our results indicate that many subcellular structures, including coated vesicles and lysosomes, are too small to contain free H(+ ions at equilibrium, thus the definition of pH based on K(w is no longer valid. Larger subcellular structures, such as mitochondria, apparently contain only a few free H(+ ions. These results indicate that pH fails to describe intracellular conditions, and that water appears to be dissociated too weakly to provide free H(+ ions as a general source for biochemical reactions. Consequences of this finding are discussed.

  8. Continuous pH monitoring in a perfused bioreactor system using an optical pH sensor

    Science.gov (United States)

    Jeevarajan, Antony S.; Vani, Sundeep; Taylor, Thomas D.; Anderson, Melody M.

    2002-01-01

    Monitoring and regulating the pH of the solution in a bioprocess is one of the key steps in the success of bioreactor operation. An in-line optical pH sensor, based on the optical absorption properties of phenol red present in the medium, was developed and tested in this work for use in NASA space bioreactors based on a rotating wall-perfused vessel system supporting a baby hamster kidney (BHK-21) cell culture. The sensor was tested over three 30-day and one 124-day cell runs. The pH sensor initially was calibrated and then used during the entire cell culture interval. The pH reported by the sensor was compared to that measured by a fiber optically coupled Shimadzu spectrophotometer and a blood gas analyzer. The maximum standard error of prediction for all the four cell runs for development pH sensor against BGA was +/-0.06 pH unit and for the fiber optically coupled Shimadzu spectrophotometer against the blood gas analyzer was +/-0.05 pH unit. The pH sensor system performed well without need of recalibration for 124 days. Copyright 2002 Wiley Periodicals, Inc.

  9. Effects of elevated summer temperatures and reduced pH on metabolism and growth of juvenile trout (Oncorhynchus mykiss) on unlimited ration

    International Nuclear Information System (INIS)

    Dockray, J.J.; Reid, S.D.; Wood, C.M.

    1996-01-01

    Juvenile trout (Oncorhynchus mykiss) were exposed to a simulated global warming - acidic water scenario over a 90-day summer period (control temperature range 13-24 o C). The addition of 2 o C to the fluctuating summer cycle of inshore Lake Ontario and H 2 SO 4 to synthetic soft water resulted in four treatments: control, acidification of control, simulated global warming alone, and global warming plus acidification. The twice-daily feeding regime raised metabolic rates to ∼75% of MO 2 (max). Large increases (from 4.5 to 11.5%) in whole-body lipid, smaller increases (from 12.0 to 15.5%) in protein, and compensating decreases in water content (from 77 to 71%) occurred in all treatments over time. The addition of 2 o C resulted in depressed appetites and growth, particularly after the period of peak temperature (days 60-90; 26 o C). Metabolic rate and nitrogenous waste excretion were also depressed. Overall, exposure to low pH resulted in increased appetites and growth, the increase of 2 o C reduced gross energy intake and increased fecal energy losses, and exposure to low pH resulted in increased energy intake and gain and better conversion efficiency. The lack of ionregulatory disturbance in trout chronically exposed to pH 5.2 suggested that dietary NaCl may have compensated for branchial ion losses. (author). 63 refs., 5 tabs., 4 figs

  10. Development and application of an excitation ratiometric optical pH sensor for bioprocess monitoring.

    Science.gov (United States)

    Badugu, Ramachandram; Kostov, Yordan; Rao, Govind; Tolosa, Leah

    2008-01-01

    The development of a fluorescent excitation ratiometric pH sensor (AHQ-PEG) using a novel allylhydroxyquinolinium (AHQ) derivative copolymerized with polyethylene glycol dimethacrylate (PEG) is described. The AHQ-PEG sensor film is shown to be suitable for real-time, noninvasive, continuous, online pH monitoring of bioprocesses. Optical ratiometric measurements are generally more reliable, robust, inexpensive, and insensitive to experimental errors such as fluctuations in the source intensity and fluorophore photobleaching. The sensor AHQ-PEG in deionized water was shown to exhibit two excitation maxima at 375 and 425 nm with a single emission peak at 520 nm. Excitation spectra of AHQ-PEG show a decrease in emission at the 360 nm excitation and an increase at the 420 nm excitation with increasing pH. Accordingly, the ratio of emission at 420:360 nm excitation showed a maximum change between pH 5 and 8 with an apparent pK(a) of 6.40. The low pK(a) value is suitable for monitoring the fermentation of most industrially important microorganisms. Additionally, the AHQ-PEG sensor was shown to have minimal sensitivity to ionic strength and temperature. Because AHQ is covalently attached to PEG, the film shows no probe leaching and is sterilizable by steam and alcohol. It shows rapid (approximately 2 min) and reversible response to pH over many cycles without any photobleaching. Subsequently, the AHQ-PEG sensor film was tested for its suitability in monitoring the pH of S. cereviseae (yeast) fermentation. The observed pH using AHQ-PEG film is in agreement with a conventional glass pH electrode. However, unlike the glass electrode, the present sensor is easily adaptable to noninvasive monitoring of sterilized, closed bioprocess environments without the awkward wire connections that electrodes require. In addition, the AHQ-PEG sensor is easily miniaturized to fit in microwell plates and microbioreactors for high-throughput cell culture applications.

  11. pH sensor calibration procedure

    OpenAIRE

    Artero Delgado, Carola; Nogueras Cervera, Marc; Manuel Lázaro, Antonio; Prat Tasias, Jordi; Prat Farran, Joana d'Arc

    2013-01-01

    This paper describes the calibration of pH sensor located at the OBSEA marine Observatory. This instrument is based on an industrial pH electrode that is connected to a CTD instrument (Conductivity, Temperature, and Depth ). The calibration of the pH sensor has been done using a high precision spectrophotometer pH meter from Institute of Marine Sciences (ICM), and in this way it has been obtained a numerical function for the p H sensor propor...

  12. Identification of a molecular pH sensor in coral.

    Science.gov (United States)

    Barott, Katie L; Barron, Megan E; Tresguerres, Martin

    2017-11-15

    Maintaining stable intracellular pH (pHi) is essential for homeostasis, and requires the ability to both sense pH changes that may result from internal and external sources, and to regulate downstream compensatory pH pathways. Here we identified the cAMP-producing enzyme soluble adenylyl cyclase (sAC) as the first molecular pH sensor in corals. sAC protein was detected throughout coral tissues, including those involved in symbiosis and calcification. Application of a sAC-specific inhibitor caused significant and reversible pHi acidosis in isolated coral cells under both dark and light conditions, indicating sAC is essential for sensing and regulating pHi perturbations caused by respiration and photosynthesis. Furthermore, pHi regulation during external acidification was also dependent on sAC activity. Thus, sAC is a sensor and regulator of pH disturbances from both metabolic and external origin in corals. Since sAC is present in all coral cell types, and the cAMP pathway can regulate virtually every aspect of cell physiology through post-translational modifications of proteins, sAC is likely to trigger multiple homeostatic mechanisms in response to pH disturbances. This is also the first evidence that sAC modulates pHi in any non-mammalian animal. Since corals are basal metazoans, our results indicate this function is evolutionarily conserved across animals. © 2017 The Author(s).

  13. Influence of pH, bleaching agents, and acid etching on surface wear of bovine enamel

    Science.gov (United States)

    Soares, Ana Flávia; Bombonatti, Juliana Fraga Soares; Alencar, Marina Studart; Consolmagno, Elaine Cristina; Honório, Heitor Marques; Mondelli, Rafael Francisco Lia

    2016-01-01

    ABSTRACT Development of new materials for tooth bleaching justifies the need for studies to evaluate the changes in the enamel surface caused by different bleaching protocols. Objective The aim of this study was to evaluate the bovine dental enamel wear in function of different bleaching gel protocols, acid etching and pH variation. Material and Methods Sixty fragments of bovine teeth were cut, obtaining a control and test areas. In the test area, one half received etching followed by a bleaching gel application, and the other half, only the bleaching gel. The fragments were randomly divided into six groups (n=10), each one received one bleaching session with five hydrogen peroxide gel applications of 8 min, activated with hybrid light, diode laser/blue LED (HL) or diode laser/violet LED (VHL) (experimental): Control (C); 35% Total Blanc Office (TBO35HL); 35% Lase Peroxide Sensy (LPS35HL); 25% Lase Peroxide Sensy II (LPS25HL); 15% Lase Peroxide Lite (LPL15HL); and 10% hydrogen peroxide (experimental) (EXP10VHL). pH values were determined by a pHmeter at the initial and final time periods. Specimens were stored, subjected to simulated brushing cycles, and the superficial wear was determined (μm). ANOVA and Tukey´s tests were applied (α=0.05). Results The pH showed a slight decrease, except for Group LPL15HL. Group LPS25HL showed the highest degree of wear, with and without etching. Conclusion There was a decrease from the initial to the final pH. Different bleaching gels were able to increase the surface wear values after simulated brushing. Acid etching before bleaching increased surface wear values in all groups. PMID:27008254

  14. A model perception on the independence of PhD students in ...

    African Journals Online (AJOL)

    Rwandan Journal of Education ... As results, we suggest that a well-trained independent PhD student from UR should be able to think critically, to initiate, to innovate and to enhance the research capabilities. Therefore ... Keywords: PhD supervision, independent researcher, PhD student, research capability, critical thinking ...

  15. [Characteristics of precipitation pH and conductivity at Mt. Huang].

    Science.gov (United States)

    Shi, Chun-e; Deng, Xue-liang; Wu, Bi-wen; Hong, Jie; Zhang, Su; Yang, Yuan-jian

    2013-05-01

    To understand the general characteristics of pH distribution and pollution in precipitation at Mt. Huang, statistical analyses were conducted for the routine measurements of pH and conductivity (K) at Mt. Huang during 2006-2011. The results showed that: (1) Over the period of study, the annual volume weighted mean (VWM) precipitation pH varied from 4.81 to 5.57, with precipitation acidity strengthening before 2009 and weakening thereafter. The precipitation acidity showed evident seasonal variations, with the VWM pH lowest in winter (4.78), and highest in summer (5.33). The occurrence frequency of acid rain was 46% , accounting for 45% of total rainfalls and with the most frequent pH falling into weak acid to neutral rain. (2) The annual VWM K varied from 16.91 to 27.84 microS x cm(-1), with no evident trend. As for ions pollution, the precipitation was relatively clean at Mt. Huang, with the most frequent K range being below 15 microS x cm(-1), followed by 15-25 microS x cm(-1). From February 2010 to December 2011, precipitation samples were collected on daily basis for ions analysis, as well as pH and K measurement in lab. Detailed comparisons were conducted between the two sets of pH and K, one set from field measurement and the other from lab measurement. The results indicated: (1) The lab measured pH (K) was highly correlated with the field pH (K); however, the lab pH tended to move towards neutral comparing with the corresponding field pH, and the shift range was closely correlated with the field pH and rainfall. The shift range of K from field to lab was highly correlated with the total ion concentration of precipitation. The field K showed evident negative correlation with the field pH with a correlation coefficient of -0.51. (2) When sampling with nylon-polyethylene bags, the statistics showed smaller bias between two sets of pH, with higher correlation coefficient between two sets of K. Furthermore, the lab K also showed evident negative correlation with

  16. CYCLES AND CRISES: HISTORY AND MODERNITY (THE RESULTS OF THE INTERNATIONAL NOBEL ECONOMIC FORUM)

    OpenAIRE

    Borys I.KHOLOD; Anatoly O.ZADOYA

    2009-01-01

    The paper analysis the main features of crisis phenomena in the early 21st century taking into consideration the overlapping stages of different types of business cycle (short and medium terms). The authors evaluate different kinds of economic cycles from the viewpoint of both history and modernity on the basis of opinions formulated during the International Nobel Economic Forum ôWord Economy in the 21th Century: Cycles and Crisesö (held in September 2008 at Dnipropetrovsk, University of Econ...

  17. Role of the bicarbonate-responsive soluble adenylyl cyclase in pH sensing and metabolic regulation

    Directory of Open Access Journals (Sweden)

    Jung-Chin eChang

    2014-02-01

    Full Text Available The evolutionarily conserved soluble adenylyl cyclase (sAC, adcy10 was recently identified as a unique source of cAMP in the cytoplasm and the nucleus. Its activity is regulated by bicarbonate and fine-tuned by calcium. As such, and in conjunction with carbonic anhydrase (CA, sAC constitutes an HCO3-/CO¬2/pH sensor. In both alpha-intercalated cells of the collecting duct and the clear cells of the epididymis, sAC is expressed at significant level and involved in pH homeostasis via apical recruitment of vacuolar H+-ATPase (VHA in a PKA-dependent manner. In addition to maintenance of pH homeostasis, sAC is also involved in metabolic regulation such as coupling of Krebs cycle to oxidative phosphorylation via bicarbonate/CO2 sensing. Additionally, sAC also regulates CFTR channel and plays an important role in regulation of barrier function and apoptosis. These observations suggest that sAC, via bicarbonate-sensing, plays an important role in maintaining homeostatic status of cells against fluctuations in their microenvironment.

  18. KOH concentration effect on the cycle life of nickel-hydrogen cells. Part 4: Results of failure analyses

    Science.gov (United States)

    Lim, H. S.; Verzwyvelt, S. A.

    1989-01-01

    KOH concentration effects on cycle life of a Ni/H2 cell have been studied by carrying out a cycle life test of ten Ni/H2 boiler plate cells which contain electrolytes of various KOH concentrations. Failure analyses of these cells were carried out after completion of the life test which accumulated up to 40,000 cycles at an 80 percent depth of discharge over a period of 3.7 years. These failure analyses included studies on changes of electrical characteristics of test cells and component analyses after disassembly of the cell. The component analyses included visual inspections, dimensional changes, capacity measurements of nickel electrodes, scanning electron microscopy, BET surface area measurements, and chemical analyses. Results have indicated that failure mode and change in the nickel electrode varied as the concentration was varied, especially, when the concentration was changed from 31 percent or higher to 26 percent or lower.

  19. Proliferation in cycle

    Energy Technology Data Exchange (ETDEWEB)

    Piao Yunsong [College of Physical Sciences, Graduate School of Chinese Academy of Sciences, Beijing 100049 (China)], E-mail: yspiao@gucas.ac.cn

    2009-06-15

    In the contracting phase with w{approx_equal}0, the scale invariant spectrum of curvature perturbation is given by the increasing mode of metric perturbation. In this Letter, it is found that if the contracting phase with w{approx_equal}0 is included in each cycle of a cycle universe, since the metric perturbation is amplified on super horizon scale cycle by cycle, after each cycle the universe will be inevitably separated into many parts independent of one another, each of which corresponds to a new universe and evolves up to next cycle, and then is separated again. In this sense, a cyclic multiverse scenario is actually presented, in which the universe proliferates cycle by cycle. We estimate the number of new universes proliferated in each cycle, and discuss the implications of this result.

  20. Proliferation in cycle

    International Nuclear Information System (INIS)

    Piao Yunsong

    2009-01-01

    In the contracting phase with w≅0, the scale invariant spectrum of curvature perturbation is given by the increasing mode of metric perturbation. In this Letter, it is found that if the contracting phase with w≅0 is included in each cycle of a cycle universe, since the metric perturbation is amplified on super horizon scale cycle by cycle, after each cycle the universe will be inevitably separated into many parts independent of one another, each of which corresponds to a new universe and evolves up to next cycle, and then is separated again. In this sense, a cyclic multiverse scenario is actually presented, in which the universe proliferates cycle by cycle. We estimate the number of new universes proliferated in each cycle, and discuss the implications of this result.

  1. Stopping Onabotulinum Treatment after the First Two Cycles Might Not Be Justified: Results of a Real-life Monocentric Prospective Study in Chronic Migraine

    Directory of Open Access Journals (Sweden)

    Paola Sarchielli

    2017-12-01

    Full Text Available IntroductionOnabotulinum toxin A (OnabotA cyclic treatment is approved for the prophylactic treatment of chronic migraine (CM, a highly disabling disorder. Although treatment response varies among patients, current guidelines suggest to stop treatment after cycle 2 if no response is achieved. This prospective study aimed to define, in real-life setting, the evolution of the response to OnabotA over five cycles of treatment among patients non-responding to cycle 1. The results of this study might help in decision-making, in particular whether prosecuting OnabotA further or not, when facing a patient not responding to cycle 1.MethodsPatients failing to respond at cycle 1 were recruited to complete five cycles. Key outcomes were: (i a ≥50% reduction in headache days, (ii a ≥50% reduction in total cumulative hours of headache on headache days and (iii a ≥5-point improvement in Headache Impact Test-6 (HIT-6 scores.ResultsOverall, 56 patients were included. Mean age was 45.7 years (female 83.9%. Severe (≥60 HIT-6 score was reported at baseline by 95.8% of patients. Responders (headache days reduction of more than 50% progressively increased cycle after cycle, doubling from cycle 2 to cycle 5 (from 27 to 48%. In addition, patients regressed from CM to episodic migraine moving on with each cycle, with 78% of them reaching less than nine migraine days/month after cycle 5. The headache days per month decreased significantly from cycle 1 to cycle 5 (overall from 23.3 ± 5.7 to 9.2 ± 3.6; p < 0.001. During 12 months (5 cycles, migraine days per month progressively abated (from 18.5 to 8.7; p < 0.001, days with symptomatic medications intake/month consistently decreased (from 17.4 to 8.1; p < 0.001, and mean HIT-6 score lowered (from 72.4 ± 5.7 to 50.2 ± 4.3; p < 0.001.ConclusionThe positive effect of OnabotA treatment spreads over the course of the treatment and might also manifest late in treatment course

  2. Review of Life Cycle Sustainability Assessment and Potential for Its Adoption at an Automotive Company

    Directory of Open Access Journals (Sweden)

    Peter Tarne

    2017-04-01

    Full Text Available The aim of this paper is to guide the next steps of a PhD thesis through a structured review of the state of the art and implementation of Life Cycle Sustainability Assessment (LCSA, and to identify challenges and potentials for its adoption at an automotive company. First, the structured literature review was conducted on LCSA to screen the current methodological and practical implementations and to identify the main research needs in the field. Second, a research on the current status of LCSA within the automotive industry was carried out by means of investigation of published sources of 15 Original Equipment Manufacturers (OEM. By combining the results of both steps and consulting with decision makers, the challenges and potential for adopting LCSA at an automotive company were identified. The main challenges for adoption of LCSA were found to be: (1 the consistent execution of the three life cycle based assessment methods; (2 the comparatively low maturity of Social Life Cycle Assessment (S-LCA; and (3 the adequate presentation and interpretation of results. Next steps towards implementation would be a case study to gather experience on the combined execution of the three life cycle based assessments at an automotive company. Furthermore, it should be determined what the needs of decision makers at an automotive company are regarding the aggregation and interpretation of environmental, social, and economic impacts.

  3. Esophageal pH monitoring

    Science.gov (United States)

    pH monitoring - esophageal; Esophageal acidity test ... Esophageal pH monitoring is used to check how much stomach acid is entering the esophagus. It also checks how well the acid is cleared downward into the ...

  4. Critical assessment of the pH of children's soap

    Directory of Open Access Journals (Sweden)

    Bruna Rafaela Mendes

    2016-06-01

    Full Text Available Abstract Objective: To evaluate the pH value of children's antibacterial soaps and syndets used in children's baths and verify whether there is information regarding pH on the product label. Methods: Quantitative, cross-sectional, analytical observational study that included ninety soap samples, both in bar and liquid presentations, as follows: 67 children's soap (group 1, 17 antibacterial soaps (group 2, and 6 syndets (group 3. Each sample had its pH measured after 1% dilution. In addition to descriptive statistics, the Pearson-Yates chi-squared test and Student's t-tests were applied, considering the minimal significance level of 5%. The Wilcoxon-Mann-Whitney test, Fisher's exact test, and the Kruskal-Wallis test were used for inferential statistics. Results: The pH levels varied considerably between liquid and bar presentations, with lower levels (4.4-7.9 found for the liquids (p < 0.05. Syndets showed pH levels close to the ideal (slightly acid and the antibacterial soaps showed the highest pH levels (up to 11.34 (p < 0.05. Only two of the soaps included in the study had information about their pH levels on the product packaging. Conclusions: Knowledge of the pH of children's soap by doctors and users is important, considering the great pH variability found in this study. Moreover, liquid soaps, and especially syndets, are the most recommended for the sensitive skin of neonates and infants, in order to guarantee skin barrier efficacy.

  5. Development of a vision-based pH reading system

    Science.gov (United States)

    Hur, Min Goo; Kong, Young Bae; Lee, Eun Je; Park, Jeong Hoon; Yang, Seung Dae; Moon, Ha Jung; Lee, Dong Hoon

    2015-10-01

    pH paper is generally used for pH interpretation in the QC (quality control) process of radiopharmaceuticals. pH paper is easy to handle and useful for small samples such as radio-isotopes and radioisotope (RI)-labeled compounds for positron emission tomography (PET). However, pHpaper-based detecting methods may have some errors due limitations of eye sight and inaccurate readings. In this paper, we report a new device for pH reading and related software. The proposed pH reading system is developed with a vision algorithm based on the RGB library. The pH reading system is divided into two parts. First is the reading device that consists of a light source, a CCD camera and a data acquisition (DAQ) board. To improve the accuracy of the sensitivity, we utilize the three primary colors of the LED (light emission diode) in the reading device. The use of three colors is better than the use of a single color for a white LED because of wavelength. The other is a graph user interface (GUI) program for a vision interface and report generation. The GUI program inserts the color codes of the pH paper into the database; then, the CCD camera captures the pH paper and compares its color with the RGB database image in the reading mode. The software captures and reports information on the samples, such as pH results, capture images, and library images, and saves them as excel files.

  6. Spectroscopic determination of pH

    International Nuclear Information System (INIS)

    Faanu, A.; Glover, E.T.; Bailey, E.; Rochelle, C.

    2009-01-01

    A technique of measuring pH at temperature range of 20 - 70 0 C and high pressure conditions of 1 - 200 atmospheres has been developed by relating the ratio of absorbance peaks of indicator solutions (basic and acidic) as a function of pH, using ultraviolet-visible spectrophotometer. The pH values of the buffer solutions measured at 20 0 C and 70 0 C indicated slight temperature dependence, while the pressure had no effect. The pH of the buffer solutions increased with temperature with relative standard deviations in the range 0.4 - 0.5 % at 95 % confidence interval. The possible causes of the temperature dependence were attributed to changes in pH values as the temperature changed. (au)

  7. Diel cycles in dissolved barium, lead, iron, vanadium, and nitrite in a stream draining a former zinc smelter site near Hegeler, Illinois

    Science.gov (United States)

    Kay, R.T.; Groschen, G.E.; Cygan, G.; Dupre, David H.

    2011-01-01

    Diel variations in the concentrations of a number of constituents have the potential to substantially affect the appropriate sampling regimen in acidic streams. Samples taken once during the course of the day cannot adequately reflect diel variations in water quality and may result in an inaccurate understanding of biogeochemical processes, ecological conditions, and of the threat posed by the water to human health and the associated wildlife. Surface water and groundwater affected by acid drainage were sampled every 60 to 90. min over a 48-hour period at a former zinc smelter known as the Hegeler Zinc Superfund Site, near Hegeler, Illinois. Diel variations related to water quality in the aquifer were not observed in groundwater. Diel variations were observed in the temperature, pH, and concentration of dissolved oxygen, nitrite, barium, iron, lead, vanadium, and possibly uranium in surface water. Temperature, dissolved oxygen, nitrite, barium, lead, and uranium generally attained maximum values during the afternoon and minimum values during the night. Iron, vanadium, and pH generally attained minimum values during the afternoon and maximum values during the night. Concentrations of dissolved oxygen were affected by the intensity of photosynthetic activity and respiration, which are dependent upon insolation. Nitrite, an intermediary in many nitrogen reactions, may have been formed by the oxidation of ammonium by dissolved oxygen and converted to other nitrogen species as part of the decomposition of organic matter. The timing of the pH cycles was distinctly different from the cycles found in Midwestern alkaline streams and likely was the result of the photoreduction of Fe3+ to Fe 2+ and variations in the intensity of precipitation of hydrous ferric oxide minerals. Diel cycles of iron and vanadium also were primarily the result of variations in the intensity of precipitation of hydrous ferric oxide minerals. The diel variation in the concentrations of lead, uranium

  8. Industrial PhD report: Sustainable Innovation

    DEFF Research Database (Denmark)

    Olesen, Gitte Gylling Hammershøj

    2011-01-01

    Erhvervs PhD rapport udarbejdet i tilknytning til Erhvervs PhD kurset der er obligatorisk for Erhvervs PhD studerende. Rapporten omhandler relationer melllem den akademiske verden og industrien i sammenhæng med PhD projektet, betragtet og analyseret gennem teori om bæredygtig innovation....

  9. On Calibration of pH Meters

    Directory of Open Access Journals (Sweden)

    Da-Ming Zhu

    2005-04-01

    Full Text Available The calibration of pH meters including the pH glass electrode, ISE electrodes,buffers, and the general background for calibration are reviewed. Understanding of basicconcepts of pH, pOH, and electrode mechanism is emphasized. New concepts of pH, pOH,as well as critical examination of activity, and activity coefficients are given. Theemergence of new solid state pH electrodes and replacement of the salt bridge with aconducting wire have opened up a new horizon for pH measurements. A pH buffer solutionwith a conducting wire may be used as a stable reference electrode. The misleadingunlimited linear Nernstian slope should be discarded. Calibration curves with 3 nonlinearportions for the entire 0—14 pH range due to the isoelectric point change effect areexplained. The potential measurement with stirring or unstirring and effects by double layer(DL and triple layer (TL will be discussed.

  10. A ph sensor based on a flexible substrate

    Science.gov (United States)

    Huang, Wen-Ding

    implanted inside the esophagus. Our pH electrode can monitor the pH changes of gastric juice in real time when the reflux happening in the esophagus. Our micro flexible pH sensor performed clear responses in each distinct pH reflux episode quickly and accurately comparing with the other commercial pH monitoring system. For the food freshness monitoring applications, we used the flexible pH sensor as a freshness indicator to monitor the pH changing profile during the food spoilage procedure. The sensor was then embedded with radio frequency identification (RFID) based passive telemetry enabling remote monitoring of food freshness. In the result, our pH-wireless RFID system presented 633Hz/pH of the sensitivity in the frequency calibration. The calibration of stability and dynamical response of the RFID system were also demonstrated before the test on food freshness monitoring. Finally, a white fish meat for long term spoilage procedure monitoring was applied and tested by using our wireless IrOx pH sensing system. Our RFID pH sensing module is able to monitor, collect and transmit the pH information continuously for 18 hours during the food spoilage procedure. In this dissertation, a micro size of IrOx/AgCl pH sensor was fabricated on a flexible substrate. The physical properties of the IrO x thin film was verified in the work. The different sensing capability such as the sensitivity, stability, reversibility, response time, repeatability, selectivity, and temperature dependence was then demonstrated in this work. After the different in-vitro tests, the pH sensor were embedded with our passive RFID circuitry for the in-vivo GERD diagnosis and food freshness monitoring application. Our wireless pH sensing system was able to deliver the accurate and quick pH sensing data wirelessly. In conclusion, our deformable IrOx pH electrodes have been demonstrated with the advantages of accommodating and conforming sensors in small spaces or curved surfaces. This miniature IrOx pH sensor

  11. A study on the generation of radioactive corrosion product at PWR for extended fuel cycle

    International Nuclear Information System (INIS)

    Min Chul Song; Kun Jai Lee

    2001-01-01

    Current nuclear power plant operating practice is to extend the time between refueling from a 12 month operating cycle to an 18-24 month period. This current to longer fuel cycles has complicated the dilemma of finding optimum pH range for the primary coolant chemistry. The International Commission on Radiological Protection (ICRP) in ICRP publication No. 60 recommends optimization of operator radiation exposure (ORE) in nuclear power plants. CRUD formed in the plants is the major source of ORE and its transport mechanism is not understood. To analyze the generation of CRUD at the extended fuel cycle, the COTRAN code, which was developed at the Korea Advanced Institute of Science and Technology (KAIST), was used. It predicts that the activity of CRUD decreases as the pH of the coolant increases. For the same period of different fuel cycles, as the operating fuel cycle duration is increased, the generation of the CRUD increases. In this paper, enriched boric acid (40% enriched 10 B concentration) for reactivity control is adopted as the required chemical shim rather than natural boric acid. The effect of the enriched boric acid (EBA) is that the neutron absorption capability of the chemical shim is maintained while decreasing the required boron and lithium concentration in the reactor coolant system. By employing enriched boric acid, the amounts of CRUD generated are reduced, because the high pH-operating period is extended. From the waste generation point of view, more filters or ion exchangers to remove CRUD are required and the amounts of waste are increased at the extended fuel cycle. (author)

  12. Impacts of beaver ponds on dissolved organic matter cycling in small temperate streams.

    Science.gov (United States)

    Larsen, J.; Lambert, T.; Larsen, A.; Lane, S.

    2017-12-01

    Beavers are engineers that modify the structure of river reaches and their hydrological functioning. By building dams, they modify the travel time of running waters and can lead to the flooding of surrounding soils and terrestrial vegetation, with potentially significant impact on biogeochemical cycles. Contradictory effects of beaver ponds on dissolved organic matter (DOM) concentration and composition have however been reported, and the underlying reasons are still unclear. In this study, we aimed to investigate the role of the landscape morphology as an important driver determining how a beaver population can affect stream DOM cycling. Four streams localized in Switzerland and Germany were visited during different seasons (spring, summer, winter) and monitored at upstream and downstream locations of beaver ponds across a hydrological cycle. The sites differed in terms of river channel morphology, presence or absence of floodplain, and vegetation cover. DOM composition was investigated through absorbance and fluorescence measurements coupled with parallel factor analysis (PARAFAC) along with stream water quality (nutrients, pH, dissolved oxygen and water temperature). The results show that the effects of beaver dams were variable, and emphasizes the importance of the geomorphological context.

  13. Effect of combined β-alanine and sodium bicarbonate supplementation on cycling performance.

    Science.gov (United States)

    Bellinger, Phillip M; Howe, Samuel T; Shing, Cecilia M; Fell, James W

    2012-08-01

    The purpose of this study was to investigate the effects of 28 d of β-alanine supplementation on 4-min cycling time trial performance and to determine whether there was an additive effect of combined β-alanine and sodium bicarbonate (NaHCO3) supplementation on high-intensity cycling performance. Fourteen highly trained cyclists (mean ± SD: age = 25.4 ± 7.2 yr, mass = 71.1 ± 7.1 kg, V˙O(2max) = 66.6 ± 5.7 mL·kg·min) supplemented for 28 d with β-alanine (65 mg·kg body mass each day) or placebo. A maximal 4-min bout of cycling was performed before supplementation (baseline) and twice after supplementation: after ingestion of NaHCO3 (300 mg·kg body mass) and ingestion of a placebo using a randomized crossover design with 2 d between trials. Blood pH and HCO3 concentration were determined before loading (postsupplementation trials) and at pretest and posttest. In the acute NaHCO3 loading trials, blood pH and HCO3 were elevated from before loading to pretest, and the magnitude of the change in HCO3 from pretest to posttest was significantly greater compared with the acute placebo loading trial (P < 0.001). Average power output in the 4-min cycling performance trial was increased in placebo + NaHCO3 (+3.1% ± 1.8%) and β-alanine + NaHCO3 (+3.3% ± 3.0%) compared with baseline (P < 0.05). β-alanine + placebo did not significantly improve average power output compared with baseline (+1.6% ± 1.7%, P = 0.20); however, magnitude-based inferences demonstrated that β-alanine + placebo was associated with a 37% likelihood of producing average power improvements. In trained cyclists, β-alanine supplementation did not significantly improve 4-min cycling performance; however, there may be a small meaningful improvement in performance. Acute NaHCO3 supplementation significantly improved 4-min cycling performance. There seemed to be a minimal additive effect of combined β-alanine and NaHCO3 supplementation.

  14. L'écriture du cycle

    OpenAIRE

    Ackerman, Ada; Conrad, Thomas; Corbellari, Alain; Genesis, La rédaction de; Grenaud-Tostain, Céline; Guermès, Sophie; Leblond, Aude; Leriche, Françoise; Lüdeke, Roger; Lumbroso, Olivier; Macke, Jean-Sébastien; Montémont, Véronique; Neefs, Jacques; Pagès, Alain; Pottier, Jean-Michel

    2016-01-01

    Textes réunis et présentés par Alain Pagès (Paris III) et Olivier Lumbroso (Paris III) Ce numéro de la revue Genesis coordonné par Alain Pagès et Olivier Lumbroso souhaite ouvrir un nouveau chantier en posant la question de l’écriture des cycles romanesques. Au-delà d’une génétique des œuvres individuelles – étudiées à travers leurs ébauches, leurs scénarios ou leurs variantes scripturales –, il propose de changer d’échelle, et d’ouvrir un nouvel espace à la perception des phénomènes de gen...

  15. Spore germination and gametophyte development of Cyathea atrovirens (Langsd. & Fisch. Domin (Cyatheaceae under different pH conditions

    Directory of Open Access Journals (Sweden)

    C. Rechenmacher

    Full Text Available Cyathea atrovirens (Langsd. & Fisch. Domin, an intensely exploited tree fern, is found inside forests in several succession stages, as well as in swamps, roadsides and unused fields in the Rio dos Sinos basin, in the state of Rio Grande do Sul, southern Brazil. This study evaluated the in vitro germination and gametophyte development of C.atrovirens under different pH conditions, as well as spore viability after different storage times at 7 ºC. The lowest germination rate of spores was obtained at pH 7.0. At pH 5.0 to 6.5, laminar gametophyte development started at 20 to 30 days of culture. Antheridia and archegonia were first observed at 35 and 128 days, respectively. Storage at 7 ºC did not affect germination rates. The capability of germination at different pH levels may explain the occurrence of the species in a wide range of habitats. The present study contributes to the understanding of the full life-cycle of C. atrovirens and to the analysis of the influence of abiotic components, providing information for the cultivation, management and conservation of the species.

  16. pH dependence of MHC class I-restricted peptide presentation

    DEFF Research Database (Denmark)

    Stryhn, A; Pedersen, L O; Romme, T

    1996-01-01

    The function of MHC class I molecules is to bind and present antigenic peptides to cytotoxic T cells. Here, we report that class I-restricted peptide presentation is strongly pH dependent. The presentation of some peptides was enhanced at acidic pH, whereas the presentation of others was inhibited....... Biochemical peptide-MHC class I binding assays demonstrated that peptide-MHC class I complexes are more stable at neutral pH than at acidic pH. We suggest that acid-dependent peptide dissociation can generate empty class I molecules and that the resulting binding potential can be exploited by a subset...

  17. A modified pH-cycling model to evaluate fluoride effect on enamel demineralization Modelo de ciclagens de pH para avaliar o efeito do fluoreto na desmineralização do esmalte

    Directory of Open Access Journals (Sweden)

    Rosane Maria Orth Argenta

    2003-09-01

    Full Text Available Since in vitro pH-cycling models are widely used to study dental caries, they should allow evaluations of fluoride effect on early stages of caries development. Therefore, acid etching on enamel surface must be avoided, enabling surface microhardness (SMH analysis. In the present study, the pH-cycling model originally described by Featherstone et al.9 (1986 was modified to preserve the enamel surface and to produce early carious lesions that could be evaluated using SMH and cross-sectional microhardness (CSMH measurements. In order to validate this modified model, a dose-response evaluation with fluoride was made. Human enamel blocks with known SMH were submitted to such regimen with the following treatments: distilled deionized water (DDW; control and solutions containing 70, 140 and 280 ppm F. Data from %SMH change and deltaZ (mineral loss showed a statistically significant negative correlation between F concentration in treatment solutions and mineral loss. In conclusion, the modified pH-cycling model allowed the evaluation of changes on the outermost enamel layer during caries development, and a dose-response effect of fluoride reducing enamel demineralization was observed.Considerando que os modelos de ciclagens de pH são amplamente usados para estudar a cárie dental, eles deveriam possibilitar a avaliação do efeito do fluoreto nos estágios iniciais do desenvolvimento da cárie. Desse modo, o ataque ácido erosivo na superfície do esmalte deve ser evitado, possibilitando a análise da microdureza de superfície (MDS. No presente estudo, o modelo de ciclagens de pH descrito por Featherstone et al.9 (1986 foi modificado para preservar a superfície do esmalte e para produzir lesões iniciais que pudessem ser avaliadas usando MDS e microdureza do esmalte seccionado longitudinalmente. Para validar esse modelo modificado, uma avaliação dose-resposta a fluoreto foi feita. Blocos de esmalte dental humano de MDS conhecida foram submetidos a

  18. Intracellular pH and 42.00 C heat response of CHO cells cultured at pH 6.6

    International Nuclear Information System (INIS)

    Cook, J.A.; Fox, M.H.

    1987-01-01

    The authors previously reported that cells under chronic low pH (6.6) conditions have altered thermotolerance. They further characterized both the doubling time (t/sub d/) and the internal pH (pH/sub 1/) of CHO cells continuously cultured at pH 6.6 for times greater than one year. The following differences were noted: 1) A t/sub d/ of 16 hr compared to a t/sub d/ of 12 hr for cells at normal pH (7.3) and a t/sub d/ of 25 hr for the acute low pH cells (pH = 6.6; incubation time = 4 hr). 2) A pH/sub i/ 0.1-0.15 pH units > normal cells and 0.3 pH units > acute low pH cells. 3) Survival at 42.0 0 C which differed from both normal and acute low pH cells. The chronic culture was still quite sensitive to 42.0 0 C treatments during the first 5 hr, but developed tolerance at a higher level than cells under acute low pH conditions. The pH/sub i/ of the chronic culture responded to 42.0 0 C heating in a manner similar to that for acute low pH cells. Whether this culture represents a normal response to long term low pH exposure, or was the response of a mutant population is at the present unknown

  19. Long-term effect of tobacco on unstimulated salivary pH.

    Science.gov (United States)

    Grover, Neeraj; Sharma, Jyoti; Sengupta, Shamindra; Singh, Sanjeet; Singh, Nishant; Kaur, Harjeet

    2016-01-01

    The aim of this study was to analyze and compare the effects of tobacco on salivary pH between tobacco chewers, smokers and controls. A total of 60 subjects (males and females) aged 25-40 years, were divided equally into three groups: Tobacco smokers (Group A), chewers (Group B) and controls (Group C). Saliva of each subject was collected under resting condition. Salivary pH was determined using the specific salivary pH meter. The mean (±standard deviation) pH for Group A was 6.75 (±0.11), Group B was 6.5 (±0.29) and Group C was 7.00 (±0.28) after comparison. The significant results showed lower salivary pH in Groups A and B as compared to controls. Salivary pH was lowest in Group B compared to Group A and Group C. This study indicates that a lower (acidic) salivary pH was observed in tobacco users as compared with control. These alterations in pH due to the long-term effect of tobacco use can render oral mucosa vulnerable to various oral and dental diseases.

  20. Evaluating nanoparticle sensor design for intracellular pH measurements.

    Science.gov (United States)

    Benjaminsen, Rikke V; Sun, Honghao; Henriksen, Jonas R; Christensen, Nynne M; Almdal, Kristoffer; Andresen, Thomas L

    2011-07-26

    Particle-based nanosensors have over the past decade been designed for optical fluorescent-based ratiometric measurements of pH in living cells. However, quantitative and time-resolved intracellular measurements of pH in endosomes and lysosomes using particle nanosensors are challenging, and there is a need to improve measurement methodology. In the present paper, we have successfully carried out time-resolved pH measurements in endosomes and lyosomes in living cells using nanoparticle sensors and show the importance of sensor choice for successful quantification. We have studied two nanoparticle-based sensor systems that are internalized by endocytosis and elucidated important factors in nanosensor design that should be considered in future development of new sensors. From our experiments it is clear that it is highly important to use sensors that have a broad measurement range, as erroneous quantification of pH is an unfortunate result when measuring pH too close to the limit of the sensitive range of the sensors. Triple-labeled nanosensors with a pH measurement range of 3.2-7.0, which was synthesized by adding two pH-sensitive fluorophores with different pK(a) to each sensor, seem to be a solution to some of the earlier problems found when measuring pH in the endosome-lysosome pathway.

  1. Integrate life-cycle assessment and risk analysis results, not methods.

    Science.gov (United States)

    Linkov, Igor; Trump, Benjamin D; Wender, Ben A; Seager, Thomas P; Kennedy, Alan J; Keisler, Jeffrey M

    2017-08-04

    Two analytic perspectives on environmental assessment dominate environmental policy and decision-making: risk analysis (RA) and life-cycle assessment (LCA). RA focuses on management of a toxicological hazard in a specific exposure scenario, while LCA seeks a holistic estimation of impacts of thousands of substances across multiple media, including non-toxicological and non-chemically deleterious effects. While recommendations to integrate the two approaches have remained a consistent feature of environmental scholarship for at least 15 years, the current perception is that progress is slow largely because of practical obstacles, such as a lack of data, rather than insurmountable theoretical difficulties. Nonetheless, the emergence of nanotechnology presents a serious challenge to both perspectives. Because the pace of nanomaterial innovation far outstrips acquisition of environmentally relevant data, it is now clear that a further integration of RA and LCA based on dataset completion will remain futile. In fact, the two approaches are suited for different purposes and answer different questions. A more pragmatic approach to providing better guidance to decision-makers is to apply the two methods in parallel, integrating only after obtaining separate results.

  2. Is high-intensity interval cycling feasible and more beneficial than continuous cycling for knee osteoarthritic patients? Results of a randomised control feasibility trial.

    Science.gov (United States)

    Keogh, Justin W; Grigg, Josephine; Vertullo, Christopher J

    2018-01-01

    attributed to one HIIT participant. Pre-post-test analyses indicated both groups significantly improved their WOMAC scores, with the HIIT group also significantly improving in the TUG and STS. The only significant between-group difference was observed in the TUG, whereby the HIIT group improved significantly more than the MICT group. No significant changes were observed in the Lequesne index, gait speed or body composition for either group. An unsupervised home-based HIIT cycle program appears somewhat feasible for middle-aged and older adults with knee OA and may produce similar improvements in health-related quality of life but greater improvements in physical function than MICT. These results need to be confirmed in larger randomised controlled trials to better elucidate the potential for HIIT to improve outcomes for those with knee OA. Additional research needs to identify and modify the potential barriers affecting the initiation and adherence to home-based HIIT cycling exercise programs by individuals with knee OA.

  3. The Halden corrosion cycling experiment IFA-560.2. Experimental results and their interpretation

    International Nuclear Information System (INIS)

    Beck, W.; Boehner, G.; Eberle, R.

    1992-01-01

    The Halden experiment IFA-560.2 was an experiment in which the corrosion behaviour of PWR fuel rodlets was investigated simultaneously under different load and cooling conditions: Permanent convective cooling at 50% power, permanent nucleate boiling at 100% power and periodic cycling between these two states. The objective was to study possible influences on the corrosion mechanism which might generically be related to the cycling operation. The oxide layer increments after 90 operations days and 60 day/night cycles were evaluated using the Siemens/KWU corrosion model regarding the special thermal hydraulic conditions of the experimental loop. The analysis proves that the layer thickness increases could be described purely following the changes in temperature caused by the power changes. No extra effect due to the frequent changes between the different cooling conditions could be observed. (orig.)

  4. A comparison of simulation results from two terrestrial carbon cycle models using three climate data sets

    International Nuclear Information System (INIS)

    Ito, Akihiko; Sasai, Takahiro

    2006-01-01

    This study addressed how different climate data sets influence simulations of the global terrestrial carbon cycle. For the period 1982-2001, we compared the results of simulations based on three climate data sets (NCEP/NCAR, NCEP/DOE AMIP-II and ERA40) employed in meteorological, ecological and biogeochemical studies and two different models (BEAMS and Sim-CYCLE). The models differed in their parameterizations of photosynthetic and phenological processes but used the same surface climate (e.g. shortwave radiation, temperature and precipitation), vegetation, soil and topography data. The three data sets give different climatic conditions, especially for shortwave radiation, in terms of long-term means, linear trends and interannual variability. Consequently, the simulation results for global net primary productivity varied by 16%-43% only from differences in the climate data sets, especially in these regions where the shortwave radiation data differed markedly: differences in the climate data set can strongly influence simulation results. The differences among the climate data set and between the two models resulted in slightly different spatial distribution and interannual variability in the net ecosystem carbon budget. To minimize uncertainty, we should pay attention to the specific climate data used. We recommend developing an accurate standard climate data set for simulation studies

  5. Constant pH Accelerated Molecular Dynamics Investigation of the pH Regulation Mechanism of Dinoflagellate Luciferase.

    Science.gov (United States)

    Donnan, Patrick H; Ngo, Phong D; Mansoorabadi, Steven O

    2018-01-23

    The bioluminescence reaction in dinoflagellates involves the oxidation of an open-chain tetrapyrrole by the enzyme dinoflagellate luciferase (LCF). The activity of LCF is tightly regulated by pH, where the enzyme is essentially inactive at pH ∼8 and optimally active at pH ∼6. Little is known about the mechanism of LCF or the structure of the active form of the enzyme, although it has been proposed that several intramolecularly conserved histidine residues in the N-terminal region are important for the pH regulation mechanism. Here, constant pH accelerated molecular dynamics was employed to gain insight into the conformational activation of LCF induced by acidification.

  6. PH og modernismen

    DEFF Research Database (Denmark)

    Ahnfeldt-Mollerup, Merete

    2012-01-01

    Artiklen kaster et kritisk blik på Poul Henningsens samfundsanalyse og dennes sammenhæng med hans design. PH ses i en bredere national og international sammenhæng. Diskussion af designmetoder, æstetik og Bauhaus.......Artiklen kaster et kritisk blik på Poul Henningsens samfundsanalyse og dennes sammenhæng med hans design. PH ses i en bredere national og international sammenhæng. Diskussion af designmetoder, æstetik og Bauhaus....

  7. A nanoporous ruthenium oxide framework for amperometric sensing of glucose and potentiometric sensing of pH

    International Nuclear Information System (INIS)

    Shim, J.H.; Kang, M.; Lee, Y.; Lee, C.

    2012-01-01

    Nanoporous ruthenium oxide frameworks (L 2 -eRuO) were electrodeposited on gold substrates by repetitive potential cycling in solutions of ruthenium(III) ions in the presence of reverse neutral micelles. The L 2 -eRuO was characterized in terms of direct oxidation of glucose and potentiometric response to pH values. The surface structures and morphologies of the L 2 -eRuO were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy, and high-resolution transmission electron microscopy. Their surface area was estimated via underpotential deposition of copper. L 2-eRuO-modified electrodes showed a 17-fold higher sensitivity (40 μA mM -1 cm -2 towards glucose in 0-4 mM concentration in solution of pH 7.4) than a RuO electrode prepared in the absence of reverse micelles. Potential interferents such as ascorbic acid, 4-acetamidophenol, uric acid and dopamine displayed no effect. The new electrode also revealed improved potentiometric response to pH changes compared to a platinum electrode of the same type. (author)

  8. Cell cycle arrest induced by inhibitors of epigenetic modifications in maize (Zea mays) seedling leaves: characterization of the process and possible mechanisms involved.

    Science.gov (United States)

    Wang, Pu; Zhang, Hao; Hou, Haoli; Wang, Qing; Li, Yingnan; Huang, Yan; Xie, Liangfu; Gao, Fei; He, Shibin; Li, Lijia

    2016-07-01

    Epigenetic modifications play crucial roles in the regulation of chromatin architecture and are involved in cell cycle progression, including mitosis and meiosis. To explore the relationship between epigenetic modifications and the cell cycle, we treated maize (Zea mays) seedlings with six different epigenetic modification-related inhibitors and identified the postsynthetic phase (G2 ) arrest via flow cytometry analysis. Total H4K5ac levels were significantly increased and the distribution of H3S10ph signalling was obviously changed in mitosis under various treatments. Further statistics of the cells in different periods of mitosis confirmed that the cell cycle was arrested at preprophase. Concentrations of hydrogen peroxide were relatively higher in the treated plants and the antioxidant thiourea could negate the influence of the inhibitors. Moreover, all of the treated plants displayed negative results in the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling (TUNEL) and γ-H2AX immunostaining assays after exposure for 3 d. Additionally, the expression level of topoisomerase genes in the treated plants was relatively lower than that in the untreated plants. These results suggest that these inhibitors of epigenetic modifications could cause preprophase arrest via reactive oxygen species formation inhibiting the expression of DNA topoisomerase genes, accompanied by changes in the H4K5ac and H3S10ph histone modifications. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  9. Effects of lowered pH on marine phytoplankton growth rates

    DEFF Research Database (Denmark)

    Berge, Terje; Daugbjerg, Niels; Andersen, Betinna Balling

    2010-01-01

    concentration of seawater. Ocean acidification may potentially both stimulate and reduce primary production by marine phytoplankton. Data are scarce on the response of marine phytoplankton growth rates to lowered pH/increased CO2. Using the acid addition method to lower the seawater pH and manipulate...... the carbonate system, we determined in detail the lower pH limit for growth rates of 2 model species of common marine phytoplankton. We also tested whether growth and production rates of 6 other common species of phytoplankton were affected by ocean acidification (lowered to pH 7.0). The lower pH limits...... statistically similar in the pH range of ~7.0 to 8.5. Our results and literature reports on growth at lowered pH indicate that marine phytoplankton in general are resistant to climate change in terms of ocean acidification, and do not increase or decrease their growth rates according to ecological relevant...

  10. Argonne Fuel Cycle Facility ventilation system -- modeling and results

    International Nuclear Information System (INIS)

    Mohr, D.; Feldman, E.E.; Danielson, W.F.

    1995-01-01

    This paper describes an integrated study of the Argonne-West Fuel Cycle Facility (FCF) interconnected ventilation systems during various operations. Analyses and test results include first a nominal condition reflecting balanced pressures and flows followed by several infrequent and off-normal scenarios. This effort is the first study of the FCF ventilation systems as an integrated network wherein the hydraulic effects of all major air systems have been analyzed and tested. The FCF building consists of many interconnected regions in which nuclear fuel is handled, transported and reprocessed. The ventilation systems comprise a large number of ducts, fans, dampers, and filters which together must provide clean, properly conditioned air to the worker occupied spaces of the facility while preventing the spread of airborne radioactive materials to clean am-as or the atmosphere. This objective is achieved by keeping the FCF building at a partial vacuum in which the contaminated areas are kept at lower pressures than the other worker occupied spaces. The ventilation systems of FCF and the EBR-II reactor are analyzed as an integrated totality, as demonstrated. We then developed the network model shown in Fig. 2 for the TORAC code. The scope of this study was to assess the measured results from the acceptance/flow balancing testing and to predict the effects of power failures, hatch and door openings, single-failure faulted conditions, EBR-II isolation, and other infrequent operations. The studies show that the FCF ventilation systems am very controllable and remain stable following off-normal events. In addition, the FCF ventilation system complex is essentially immune to reverse flows and spread of contamination to clean areas during normal and off-normal operation

  11. Development of pH sensitive polymeric nanoparticles of erythromycin stearate

    Directory of Open Access Journals (Sweden)

    Sulekha Bhadra

    2016-01-01

    Full Text Available Context: Bioavailability of conventional tablet of erythromycin stearate is low as it is unstable at acidic pH and also shows a low dissolution rate. Objective: It was proposed to protect it from the acidic condition of the stomach along with an increase in dissolution rate by formulating pH sensitive nanoparticles. Materials and Methods: The nanoparticles were prepared by the solvent evaporation technique using different quantities of Eudragit L100-55 and polyvinyl alcohol (PVA. Size reduction was achieved by high speed homogenization technique using Digital Ultra Turrax homogenizer. The formulation was optimized using 32 factorial design, keeping drug polymer ratio and surfactant concentration as independent variables. Particle size, entrapment efficiency, and drug-release (DR were studied as dependent variables. Results: Optimized batch containing 1:0.3 erythromycin stearate: Eudragit L100-55 ratio and 1.0% PVA showed 8.24 ± 0.71% DR in pH 1.2 in 1-h and 90.38 ± 5.97% in pH 5.5 and pH 6.8 within 2-h, respectively. Discussion: The optimized batch exhibited lower release in acidic pH and faster release in higher pH compared to the marketed preparation. Conclusion: Thus the present study concludes that pH sensitive nanoparticles of erythromycin stearate increases the dissolution of the drug in intestinal pH and also protect it from acidic pH, which may help in improving the bioavailability of erythromycin.

  12. ISFET pH Sensitivity: Counter-Ions Play a Key Role.

    Science.gov (United States)

    Parizi, Kokab B; Xu, Xiaoqing; Pal, Ashish; Hu, Xiaolin; Wong, H S Philip

    2017-02-02

    The Field Effect sensors are broadly used for detecting various target analytes in chemical and biological solutions. We report the conditions under which the pH sensitivity of an Ion Sensitive Field Effect transistor (ISFET) sensor can be significantly enhanced. Our theory and simulations show that by using pH buffer solutions containing counter-ions that are beyond a specific size, the sensor shows significantly higher sensitivity which can exceed the Nernst limit. We validate the theory by measuring the pH response of an extended gate ISFET pH sensor. The consistency and reproducibility of the measurement results have been recorded in hysteresis free and stable operations. Different conditions have been tested to confirm the accuracy and validity of our experiment results such as using different solutions, various oxide dielectrics as the sensing layer and off-the-shelf versus IC fabricated transistors as the basis of the ISFET sensor.

  13. The kinetics of the photochemical reaction cycle of deuterated bacteriorhodopsin and pharaonis halorhodopsin

    International Nuclear Information System (INIS)

    Szakacs, Julianna; Lakatos, Melinda; Varo, Gy.; Ganea, Constanta

    2005-01-01

    Kinetic isotope effects in the photochemical reaction cycle of bacteriorhodopsin and pharaonis halorhodopsin were determined in H 2 O and D 2 O at normal pH, to get insight in the proton dependent steps of the transport process. All the steps of the bacteriorhodopsin photocycle at normal pH exhibited a strong isotope effect. In the case of halorhodopsin in both the chloride and nitrate transporting conditions the photocycle was not strongly affected by the deuterium exchange. In the case of chloride, a slight slow down of the photocycle could be observed. On the opposite, in the nitrate transport conditions a reverse effect is present. (author)

  14. H3S10ph broadly marks early-replicating domains in interphase ESCs and shows reciprocal antagonism with H3K9me2.

    Science.gov (United States)

    Chen, Carol C L; Goyal, Preeti; Karimi, Mohammad M; Abildgaard, Marie H; Kimura, Hiroshi; Lorincz, Matthew C

    2018-01-01

    Phosphorylation of histone H3 at serine 10 (H3S10ph) by Aurora kinases plays an important role in mitosis; however, H3S10ph also marks regulatory regions of inducible genes in interphase mammalian cells, implicating mitosis-independent functions. Using the fluorescent ubiquitin-mediated cell cycle indicator (FUCCI), we found that 30% of the genome in interphase mouse embryonic stem cells (ESCs) is marked with H3S10ph. H3S10ph broadly demarcates gene-rich regions in G1 and is positively correlated with domains of early DNA replication timing (RT) but negatively correlated with H3K9me2 and lamin-associated domains (LADs). Consistent with mitosis-independent kinase activity, this pattern was preserved in ESCs treated with Hesperadin, a potent inhibitor of Aurora B/C kinases. Disruption of H3S10ph by expression of nonphosphorylatable H3.3S10A results in ectopic spreading of H3K9me2 into adjacent euchromatic regions, mimicking the phenotype observed in Drosophila JIL-1 kinase mutants . Conversely, interphase H3S10ph domains expand in Ehmt1 (also known as Glp ) null ESCs, revealing that H3S10ph deposition is restricted by H3K9me2. Strikingly, spreading of H3S10ph at RT transition regions (TTRs) is accompanied by aberrant transcription initiation of genes co-oriented with the replication fork in Ehmt1 -/- and Ehmt2 -/- ESCs, indicating that establishment of repressive chromatin on the leading strand following DNA synthesis may depend upon these lysine methyltransferases. H3S10ph is also anti-correlated with H3K9me2 in interphase murine embryonic fibroblasts (MEFs) and is restricted to intragenic regions of actively transcribing genes by EHMT2. Taken together, these observations reveal that H3S10ph may play a general role in restricting the spreading of repressive chromatin in interphase mammalian cells. © 2018 Chen et al.; Published by Cold Spring Harbor Laboratory Press.

  15. Optimum pH and pH Stability of Crude Polyphenol Oxidase (PPO ...

    African Journals Online (AJOL)

    The effect of pH on the activity and stability of crude polyphenol oxidase (PPO) extracted from garden egg (Solanum aethiopicum), pawpaw (Carica papaya), pumpkin ... Optimum pH values were found to be 6.0,6.5,6.0, 4.5 and 4.0/or 8.0 for the enzyme extracted from Solanum aethiopicum, Carica papaya, Cucurbita pepo, ...

  16. The Hamburg oceanic carbon cycle circulation model. Cycle 1

    International Nuclear Information System (INIS)

    Maier-Reimer, E.; Heinze, C.

    1992-02-01

    The carbon cycle model calculates the prognostic fields of oceanic geochemical carbon cycle tracers making use of a 'frozen' velocity field provided by a run of the LSG oceanic circulation model (see the corresponding manual, LSG=Large Scale Geostrophic). The carbon cycle model includes a crude approximation of interactions between sediment and bottom layer water. A simple (meridionally diffusive) one layer atmosphere model allows to calculate the CO 2 airborne fraction resulting from the oceanic biogeochemical interactions. (orig.)

  17. Label-Free Carbon-Dots-Based Ratiometric Fluorescence pH Nanoprobes for Intracellular pH Sensing.

    Science.gov (United States)

    Shangguan, Jingfang; He, Dinggeng; He, Xiaoxiao; Wang, Kemin; Xu, Fengzhou; Liu, Jinquan; Tang, Jinlu; Yang, Xue; Huang, Jin

    2016-08-02

    Measuring pH in living cells is of great importance for better understanding cellular functions as well as providing pivotal assistance for early diagnosis of diseases. In this work, we report the first use of a novel kind of label-free carbon dots for intracellular ratiometric fluorescence pH sensing. By simple one-pot hydrothermal treatment of citric acid and basic fuchsin, the carbon dots showing dual emission bands at 475 and 545 nm under single-wavelength excitation were synthesized. It is demonstrated that the fluorescence intensities of the as-synthesized carbon dots at the two emissions are pH-sensitive simultaneously. The intensity ratio (I475 nm/I545 nm) is linear against pH values from 5.2 to 8.8 in buffer solution, affording the capability as ratiometric probes for intracellular pH sensing. It also displays that the carbon dots show excellent reversibility and photostability in pH measurements. With this nanoprobe, quantitative fluorescence imaging using the ratio of two emissions (I475 nm/I545 nm) for the detection of intracellular pH were successfully applied in HeLa cells. In contrast to most of the reported nanomaterials-based ratiometric pH sensors which rely on the attachment of additional dyes, these carbon-dots-based ratiometric probes are low in toxicity, easy to synthesize, and free from labels.

  18. Life cycle inventory and external costs of the gas fuel cycle. An overview of the main results and a brief comparison with other fuels

    International Nuclear Information System (INIS)

    Torfs, R.; De Nocker, L.; Wouters, G.

    1999-01-01

    In the context of a research project funded by the Belgian electricity utilities Electrabel/SPE, VITO made a life cycle inventory of the primary energy use and airborne emissions (including greenhouse gases, SO2 and NOx) of different fuels. Consequently, the impacts of these pollutants on human health, manmade and the natural environment are quantified and these impacts are valued in monetary terms. This analysis is based on the European ExternE methodology to estimate the external costs of energy. The LCI and external cost analysis confirm clearly that natural gas is a relative clean fossil fuel cycle. External cost are in the range of 1.2 to 2.6 EUROcent /kWh, which roughly corresponds from 30 % to 80 % of the private production costs. These results are introduced into a software module, which allows the utilities to compare economic costs and environmental benefits of different measures to reduce CO2 emissions. (author)

  19. Resilience and recovery of Dehalococcoides mccartyi following low pH exposure.

    Science.gov (United States)

    Yang, Yi; Cápiro, Natalie L; Yan, Jun; Marcet, Tyler F; Pennell, Kurt D; Löffler, Frank E

    2017-12-01

    Bioremediation treatment (e.g. biostimulation) can decrease groundwater pH with consequences for Dehalococcoides mccartyi (Dhc) reductive dechlorination activity. To explore the pH resilience of Dhc, the Dhc-containing consortium BDI was exposed to pH 5.5 for up to 40 days. Following 8- and 16-day exposure periods to pH 5.5, dechlorination activity and growth recovered when returned to pH 7.2; however, the ability of the culture to dechlorinate vinyl chloride (VC) to ethene was impaired (i.e. decreased rate of VC transformation). Dhc cells exposed to pH 5.5 for 40 days did not recover the ethene-producing phenotype upon transfer to pH 7.2 even after 200 days of incubation. When returned to pH 7.2 conditions after an 8-, a 16- and a 40-day low pH exposure, tceA and vcrA genes showed distinct fold increases, suggesting Dhc strain-specific responses to low pH exposure. Furthermore, a survey of Dhc biomarker genes in groundwater samples revealed the average abundances of Dhc 16S rRNA, tceA and vcrA genes in pH 4.5-6 groundwater were significantly lower (P-value pH 6-8.3 groundwater. Overall, the results of the laboratory study and the assessment of field data demonstrate that sustained Dhc activity should not be expected in low pH groundwater, and the duration of low pH exposure affects the ability of Dhc to recover activity at circumneutral pH. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  20. Design of Artificial Neural Network-Based pH Estimator

    Directory of Open Access Journals (Sweden)

    Shebel A. Alsabbah

    2010-10-01

    Full Text Available Taking into consideration the cost, size and drawbacks might be found with real hardware instrument for measuring pH values such that the complications of the wiring, installing, calibrating and troubleshooting the system, would make a person look for a cheaper, accurate, and alternative choice to perform the measuring operation, Where’s hereby, a feedforward artificial neural network-based pH estimator has to be proposed. The proposed estimator has been designed with multi- layer perceptrons. One input which is a measured base stream and two outputs represent pH values at strong base and strong/weak acids for a titration process. The created data base has been obtained with consideration of temperature variation. The final numerical results ensure the effectiveness and robustness of the design neural network-based pH estimator.

  1. pH sensitivity of emeraldine salt polyaniline and poly(vinyl butyral) blend

    International Nuclear Information System (INIS)

    Nguyen, Hoa Duyen; Hoang, Ngoc Vu; Le, Nguyen Ngan; Nguyen, Thi Ngoc Nhien; Doan, Duc Chanh Tin; Dang, Mau Chien; Nguyen, Thi Ha

    2014-01-01

    pH sensitivity of emeraldine salt polyaniline (ES-PANI) and poly(vinyl butyral) (PVB) blend film was investigated. This blend film can be used as a pH sensing element in new-type pH sensors to replace traditional instruments based on fragile glass electrodes for pH measurement of water in aquaculture farming. Structural and optical characteristic of PANI were studied by Fourier transform infrared spectroscopy (FTIR) and ultraviolet visible spectroscopy (UV–vis). Electrical characterization of ES-PANI:PVB blend films versus pH was performed with chemiresistors fabricated by micro-lithography. A ES-PANI:PVB layer was drop-coated on comb-shaped platinum electrodes patterned on SiO 2 /Si substrates. Scanning electron microscope (SEM) and optical microscope were used to investigate morphology of the fabricated platinum electrodes and the coated polymer blend films. I–V measurements of the polymer-coated chemiresistors were performed at very low relative humidity after the polymer films were exposed to pH 1–8. The results showed that logarithm of electrical resistance of the ES-PANI:PVB films increased almost linearly as pH increased from 1 to 8. The initial results showed that the PANI blend-coated chemiresistors can be used as pH sensors for water quality monitoring. (paper)

  2. Enhanced bioelectricity generation of air-cathode buffer-free microbial fuel cells through short-term anolyte pH adjustment.

    Science.gov (United States)

    Ren, Yueping; Chen, Jinli; Li, Xiufen; Yang, Na; Wang, Xinhua

    2018-04-01

    Short-term initial anolyte pH adjustment can relieve the performance deterioration of the single-chamber air-cathode buffer-free microbial fuel cell (BFMFC) caused by anolyte acidification. Adjusting the initial anolyte pH to 9 in 5 running cycles is the optimum strategy. The relative abundance of the electrochemically active Geobacter in the KCl-pH9-MFC anode biofilm increased from 59.01% to 75.13% after the short-term adjustment. The maximum power density (P max ) of the KCl-pH9-MFC was elevated from 316.4mW·m -2 to 511.6mW·m -2 , which was comparable with that of the PBS-MFC. And, after the short-term adjusting, new equilibrium between the anolyte pH and the anode biofilm electrochemical activity has been established in the BFMFC, which ensured the sustainability of the improved bioelectricity generation performance. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Proteomics analysis of Fusarium proliferatum under various initial pH during fumonisin production.

    Science.gov (United States)

    Li, Taotao; Gong, Liang; Wang, Yong; Chen, Feng; Gupta, Vijai Kumar; Jian, Qijie; Duan, Xuewu; Jiang, Yueming

    2017-07-05

    Fusarium proliferatum as a fungal pathogen can produce fumonisin which causes a great threat to animal and human health. Proteomic approach was a useful tool for investigation into mycotoxin biosynthesis in fungal pathogens. In this study, we analyzed the fumonisin content and mycelium proteins of Fusarium proliferatum cultivated under the initial pH5 and 10. Fumonisin production after 10days was significantly induced in culture condition at pH10 than pH5. Ninety nine significantly differently accumulated protein spots under the two pH conditions were detected using two dimensional polyacrylamide gel electrophoresis and 89 of these proteins were successfully identified by MALDI-TOF/TOF and LC-ESI-MS/MS analysis. Among these 89 proteins, 45 were up-regulated at pH10 while 44 were up-accumulated at pH5. At pH10, these proteins were found to involve in the modification of fumonisin backbone including up-regulated polyketide synthase, cytochrome P450, S-adenosylmethionine synthase and O-methyltransferase, which might contribute to the induction of fumonisin production. At pH5, these up-regulated proteins such as l-amino-acid oxidase, isocitrate dehydrogenase and citrate lyase might inhibit the condensation of fumonisin backbone, resulting in reduced production of fumonisins. These results may help us to understand the molecular mechanism of the fumonisin synthesis in F. proliferatum. To extend our understanding of the mechanism of the fumonisin biosynthesis of F. proliferatum, we reported the fumonisin production in relation to the differential proteins of F. proliferatum mycelium under two pH culture conditions. Among these 89 identified spots, 45 were up-accumulated at pH10 while 44 were up-accumulated at pH5. Our results revealed that increased fumonisin production at pH10 might be related to the induction of fumonisin biosynthesis caused by up-regulation of polyketide synthase, cytochrome P450, S-adenosylmethionine synthase and O-methyltransferase. Meanwhile, the

  4. Cycling infrastructure for reducing cycling injuries in cyclists.

    Science.gov (United States)

    Mulvaney, Caroline A; Smith, Sherie; Watson, Michael C; Parkin, John; Coupland, Carol; Miller, Philip; Kendrick, Denise; McClintock, Hugh

    2015-12-10

    Cycling is an attractive form of transport. It is beneficial to the individual as a form of physical activity that may fit more readily into an individual's daily routine, such as for cycling to work and to the shops, than other physical activities such as visiting a gym. Cycling is also beneficial to the wider community and the environment as a result of fewer motorised journeys. Cyclists are seen as vulnerable road users who are frequently in close proximity to larger and faster motorised vehicles. Cycling infrastructure aims to make cycling both more convenient and safer for cyclists. This review is needed to guide transport planning. To:1. evaluate the effects of different types of cycling infrastructure on reducing cycling injuries in cyclists, by type of infrastructure;2. evaluate the effects of cycling infrastructure on reducing the severity of cycling injuries in cyclists;3. evaluate the effects of cycling infrastructure on reducing cycling injuries in cyclists with respect to age, sex and social group. We ran the most recent search on 2nd March 2015. We searched the Cochrane Injuries Group Specialised Register, CENTRAL (The Cochrane Library), MEDLINE (OvidSP), Embase Classic + Embase(OvidSP), PubMed and 10 other databases. We searched websites, handsearched conference proceedings, screened reference lists of included studies and previously published reviews and contacted relevant organisations. We included randomised controlled trials, cluster randomised controlled trials, controlled before-after studies, and interrupted time series studies which evaluated the effect of cycling infrastructure (such as cycle lanes, tracks or paths, speed management, roundabout design) on cyclist injury or collision rates. Studies had to include a comparator, that is, either no infrastructure or a different type of infrastructure. We excluded studies that assessed collisions that occurred as a result of competitive cycling. Two review authors examined the titles and

  5. 3 Steps to Great Coaching: A Simple but Powerful Instructional Coaching Cycle Nets Results

    Science.gov (United States)

    Knight, Jim; Elford, Marti; Hock, Michael; Dunekack, Devona; Bradley, Barbara; Deshler, Donald D.; Knight, David

    2015-01-01

    In this article the authors describe a three-step instructional coaching cycle that can helps coaches become more effective. The article provides the steps and related components to: (1) Identify; (2) Learn; and (3) Improve. While the instructional coaching cycle is only one effective coaching program, coaches also need professional learning that…

  6. Proceedings of the First PhD Symposium on Sustainable Ultrascale Computing Systems (NESUS PhD 2016)

    OpenAIRE

    Carretero Pérez, Jesús; García Blas, Javier; Petcu, Dana

    2016-01-01

    Proceedings of the First PhD Symposium on Sustainable Ultrascale Computing Systems (NESUS PhD 2016) Timisoara, Romania. February 8-11, 2016. The PhD Symposium was a very good opportunity for the young researchers to share information and knowledge, to present their current research, and to discuss topics with other students in order to look for synergies and common research topics. The idea was very successful and the assessment made by the PhD Student was very good. It also helped t...

  7. Effects of pH on nitrogen transformations in media-based aquaponics.

    Science.gov (United States)

    Zou, Yina; Hu, Zhen; Zhang, Jian; Xie, Huijun; Guimbaud, Christophe; Fang, Yingke

    2016-06-01

    To investigate the effects of pH on performance and nitrogen transformations in aquaponics, media-based aquaponics operated at pH 6.0, 7.5 and 9.0 were systematically examined and compared in this study. Results showed that nitrogen utilization efficiency (NUE) reached its maximum of 50.9% at pH 6.0, followed by 47.3% at pH 7.5 and 44.7% at pH 9.0. Concentrations of nitrogen compounds (i.e., TAN, NO2(-)-N and NO3(-)-N) in three pH systems were all under tolerable levels. pH had significant effect on N2O emission and N2O conversion ratio decreased from 2.0% to 0.6% when pH increased from 6.0 to 9.0, mainly because acid environment would inhibit denitrifiers and lead to higher N2O emission. 75.2-78.5% of N2O emission from aquaponics was attributed to denitrification. In general, aquaponics was suggested to maintain pH at 6.0 for high NUE, and further investigations on N2O mitigation strategy are needed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. BWROPT: A multi-cycle BWR fuel cycle optimization code

    Energy Technology Data Exchange (ETDEWEB)

    Ottinger, Keith E.; Maldonado, G. Ivan, E-mail: Ivan.Maldonado@utk.edu

    2015-09-15

    Highlights: • A multi-cycle BWR fuel cycle optimization algorithm is presented. • New fuel inventory and core loading pattern determination. • The parallel simulated annealing algorithm was used for the optimization. • Variable sampling probabilities were compared to constant sampling probabilities. - Abstract: A new computer code for performing BWR in-core and out-of-core fuel cycle optimization for multiple cycles simultaneously has been developed. Parallel simulated annealing (PSA) is used to optimize the new fuel inventory and placement of new and reload fuel for each cycle considered. Several algorithm improvements were implemented and evaluated. The most significant of these are variable sampling probabilities and sampling new fuel types from an ordered array. A heuristic control rod pattern (CRP) search algorithm was also implemented, which is useful for single CRP determinations, however, this feature requires significant computational resources and is currently not practical for use in a full multi-cycle optimization. The PSA algorithm was demonstrated to be capable of significant objective function reduction and finding candidate loading patterns without constraint violations. The use of variable sampling probabilities was shown to reduce runtime while producing better results compared to using constant sampling probabilities. Sampling new fuel types from an ordered array was shown to have a mixed effect compared to random new fuel type sampling, whereby using both random and ordered sampling produced better results but required longer runtimes.

  9. Computer model of hydroponics nutrient solution pH control using ammonium.

    Science.gov (United States)

    Pitts, M; Stutte, G

    1999-01-01

    A computer simulation of a hydroponics-based plant growth chamber using ammonium to control pH was constructed to determine the feasibility of such a system. In nitrate-based recirculating hydroponics systems, the pH will increase as plants release hydroxide ions into the nutrient solution to maintain plant charge balance. Ammonium is an attractive alternative to traditional pH controls in an ALSS, but requires careful monitoring and control to avoid overdosing the plants with ammonium. The primary advantage of using NH4+ for pH control is that it exploits the existing plant nutrient uptake charge balance mechanisms to maintain solution pH. The simulation models growth, nitrogen uptake, and pH of a l-m2 stand of wheat. Simulation results indicated that ammonium-based control of nutrient solution pH is feasible using a proportional integral controller. Use of a 1 mmol/L buffer (Ka = 1.6 x 10(-6)) in the nutrient solution is required.

  10. The acid test of fluoride: how pH modulates toxicity.

    Directory of Open Access Journals (Sweden)

    Ramaswamy Sharma

    2010-05-01

    Full Text Available It is not known why the ameloblasts responsible for dental enamel formation are uniquely sensitive to fluoride (F(-. Herein, we present a novel theory with supporting data to show that the low pH environment of maturating stage ameloblasts enhances their sensitivity to a given dose of F(-. Enamel formation is initiated in a neutral pH environment (secretory stage; however, the pH can fall to below 6.0 as most of the mineral precipitates (maturation stage. Low pH can facilitate entry of F(- into cells. Here, we asked if F(- was more toxic at low pH, as measured by increased cell stress and decreased cell function.Treatment of ameloblast-derived LS8 cells with F(- at low pH reduced the threshold dose of F(- required to phosphorylate stress-related proteins, PERK, eIF2alpha, JNK and c-jun. To assess protein secretion, LS8 cells were stably transduced with a secreted reporter, Gaussia luciferase, and secretion was quantified as a function of F(- dose and pH. Luciferase secretion significantly decreased within 2 hr of F(- treatment at low pH versus neutral pH, indicating increased functional toxicity. Rats given 100 ppm F(- in their drinking water exhibited increased stress-mediated phosphorylation of eIF2alpha in maturation stage ameloblasts (pH<6.0 as compared to secretory stage ameloblasts (pH approximately 7.2. Intriguingly, F(--treated rats demonstrated a striking decrease in transcripts expressed during the maturation stage of enamel development (Klk4 and Amtn. In contrast, the expression of secretory stage genes, AmelX, Ambn, Enam and Mmp20, was unaffected.The low pH environment of maturation stage ameloblasts facilitates the uptake of F(-, causing increased cell stress that compromises ameloblast function, resulting in dental fluorosis.

  11. Latitude and pH driven trends in the molecular composition of DOM across a north south transect along the Yenisei River

    Science.gov (United States)

    Roth, Vanessa-Nina; Dittmar, Thorsten; Gaupp, Reinhard; Gleixner, Gerd

    2013-12-01

    We used electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) to identify the molecular composition of dissolved organic matter (DOM) collected from different ecosystems along a transect crossing Siberia’s northern and middle Taiga. This information is urgently needed to help elucidate global carbon cycling and export through Russian rivers. In total, we analyzed DOM samples from eleven Yenisei tributaries and seven bogs. Freeze-dried and re-dissolved DOM was desalted via solid phase extraction (SPE) and eluted in methanol for ESI-FT-ICR-MS measurements. We recorded 15209 different masses and identified 7382 molecular formulae in the mass range between m/z = 150 and 800. We utilized the relative FT-ICR-MS signal intensities of 3384 molecular formulae above a conservatively set limit of detection and summarized the molecular characteristics for each measurement using ten magnitude-weighted parameters ((O/C)w, (H/C)w, (N/C)w, (DBE)w, (DBE/C)w, (DBE/O)w, (DBE-O)w, (C#)w, (MW)w and (AI)w) for redundancy analysis. Consequently, we revealed that the molecular composition of DOM depends mainly on pH and geographical latitude. After applying variation partitioning to the peak data, we isolated molecular formulae that were strongly positive or negatively correlated with latitude and pH. We used the chemical information from 13 parameters (C#, H#, N#, O#, O/C, H/C, DBE, DBE/C, DBE/O, AI, N/C, DBE-O and MW) to characterize the extracted molecular formulae. Using latitude along the gradient representing climatic variation, we found a higher abundance of smaller molecules, nitrogen-containing compounds and unsaturated Cdbnd C functionalities at higher latitudes. As possible reasons for the different molecular characteristics occurring along this gradient, we suggested that the decomposition was temperature dependent resulting to a higher abundance of non-degraded lignin-derived phenolic substances. We demonstrated that bog samples

  12. DFT Study of PH3 Physisorption and Chemisorptions on Boron Nitride Nanotubes

    Science.gov (United States)

    Rakhshi, Mahdi; Mohsennia, Mohsen; Rasa, Hossein

    2018-03-01

    The adsorption of PH3 molecules on the NiB,N-doped(4,4) and (5,5) BNNTS surfaces has been investigated using density functional theory (DFT). The adsorption energies, geometric and electronic structures of the adsorbed systems were studied to judge the possible application of NiB,N-doped BNNTS in PH3 monitoring systems. Our calculated results showed that NiB,N-doped BNNTS had much higher adsorption energy and shorter binding distances than pure BNNTS owning to chemisorptions of the PH3 molecule. The obtained density of states (DOS) and frontier orbitals demonstrated that the orbital hybridization was obvious between the PH3 molecule and NiB,N-doped BNNTS. However, due to weak physisorption according to the total electron density maps, there was no evidence for hybridization between PH3 molecule and pure BNNTS. It was shown that after doping of Ni atom, the primary symmetry of BNNTS decreased which enhanced the chemical activity of BNNTS towards PH3 molecules. According to the obtained results, we highlight the high potential application of NiB,N-doped BNNTS in the design and fabrication of PH3 sensing devices.

  13. Novel robust cellulose-based foam with pH and light dual-response for oil recovery

    Science.gov (United States)

    Wang, Qian; Meng, Guihua; Wu, Jianning; Wang, Yixi; Liu, Zhiyong; Guo, Xuhong

    2018-05-01

    We fabricated pH and light dual-responsive adsorption materials which could induce the transition of surface wettability between hydrophobicity and hydrophilicity by using ATRP. The structure and morphology of adsorption materials were confirmed by ATR-FTIR, XPS, TGA and SEM. It showed that the modified cellulose (CE)-based foam was hydrophobic, which can adsorb a range of oils and organic solvents in water under pH = 7.0 or visible light irradiation (λ > 500 nm). Meanwhile, the wettability of robust CE-based foam can convert hydrophobicity into hydrophilicity and underwater oleophobicity under pH = 3.0 or UV irradiation (λ = 365 nm), giving rise to release oils and organic solvents. Most important of all, the adsorption and desorption processes of the modified CE-based foam could be switched by external stimuli. Furthermore, the modified CE-based foam was not damaged and still retained original performance after reversible cycle repeated for many times with variation of surface wettability. In short, it indicates that CE-based foam materials with switchable surface wettability are new responsive absorbent materials and have owned potential application in the treatment of oil recovery.

  14. The pH Game.

    Science.gov (United States)

    Chemecology, 1996

    1996-01-01

    Describes a game that can be used to teach students about the acidity of liquids and substances around their school and enable them to understand what pH levels tell us about the environment. Students collect samples and measure the pH of water, soil, plants, and other natural material. (DDR)

  15. Difference flow measurements and hydraulic interference test in ONKALO at Olkiluoto drillholes ONK-PH16 and ONK-PH17

    Energy Technology Data Exchange (ETDEWEB)

    Komulainen, J.; Pekkanen, J. [Poyry Finland Oy, Espoo (Finland)

    2012-08-15

    The Posiva Flow Log, Difference Flow Method (PFL DIFF) uses a flowmeter that incorporates a flow guide and can be used for relatively quick determinations of hydraulic conductivity and hydraulic head in fractures/fractured zones in cored drillholes. This report presents the principles of the method as well as the results of the measurements carried out in the underground facilities of ONKALO. The measurements were conducted in pilot holes ONK-PH16 and ONK-PH17 between October 12 and December 29, 2010. The aim of the measurements was to detect water conducting fractures and hydraulic interference between pilot holes ONK-PH16 and ONK-PH17. The flow rate into a 0.5 m long test section was measured using 0.1 m point intervals. The flowing fractures in both pilot holes were obtained between 50 m - 80 m. For hydraulic interference test one drillhole was closed with packers to increase its pressure. Flow response to the increased pressure was measured in the other drillhole. The flow guide of the PFL DIFF probe encloses an electrode for single point resistance measurement, which was carried out with 0.01 m point intervals during the automatic flow measurements. The flow measurement and the single point resistance measurement were used to locate flowing fractures and evaluate their transmissivity. Electrical conductivity (EC) and temperature of water were registered during automatic flow logging. The conductivity values are temperature corrected to 25 deg C. The distance between the drillholes is about 14 m. Flow response in fractures of open ONK-PH16 could be detected when pressure was changed in ONK-PH17. (orig.)

  16. pH distribution in human tumors

    International Nuclear Information System (INIS)

    Thistlethwaite, A.J.; Leeper, D.B.; Moylan, D.J.; Nerlinger, R.E.

    1984-01-01

    pH distribution in human tumors is being determined to evaluate this parameter as a prognostic indicator of hyperthermia response. pH is measured by a modified glass pH electrode (21g, model MI 408, Microelectrodes, Inc., Londonderry, NH) inserted through an 18g open-ended Angiocath. Eight tumors have been evaluated to date; and of those, 3 were also assayed after the first heat treatment coincident with determination of blood flow. Tumors were between 2-5 cm, of various histologies, and of primary, recurrent, or metastatic origin. 2-4 measurements were made per tumor. Pretreatment readings were between 6.4 and 7.2 pH units. As tumor blood flow increased after 1 hr heating (41.5 - 43 0 ) pH rose 0.1 - 0.3 units. Normal rat muscle yields pH readings of 7.35 - 7.45. Although there was considerable heterogeneity of pH within tumors, accuracy and drift were not a problem. 5-15 min were required for pH stabilization after catheter insertion and <5 min after electrode insertion. A saline wheal was used for anesthesia to preclude modification of pH by anesthetics. Patient tolerance has not been a problems. This study suggests that human tumor tissue has a preponderance of areas more acidic than normal tissue. This may serve to sensitize tumor cells to hyperthermia and provide a prognostic indicator of tumor response

  17. pH adjustment of human blood plasma prior to bioanalytical sample preparation

    NARCIS (Netherlands)

    Hendriks, G.; Uges, D. R. A.; Franke, J. P.

    2008-01-01

    pH adjustment in bioanalytical sample preparation concerning ionisable compounds is one of the most common sample treatments. This is often done by mixing an aliquot of the sample with a proper buffer adjusted to the proposed pH. The pH of the resulting mixture however, does not necessarily have to

  18. Acid skim milk gels: The gelation process as affected by preheated pH

    NARCIS (Netherlands)

    Lakemond, C.M.M.; Vliet, van T.

    2008-01-01

    The effect of preheating milk (10 min 80 [degree sign]C) at pH values from 6.20 to 6.90 on formation of acid skim milk gels was studied by dynamic oscillation measurements. Up to pH 6.65 a higher pH of heating (pHheating) resulted in a higher G'. Since below pH 4.9 the development of

  19. Hydrogel-coated fiber Bragg grating sensor for pH monitoring

    Science.gov (United States)

    Pabbisetti, Vayu Nandana Kishore; Madhuvarasu, Sai Shankar

    2016-06-01

    We present a fiber-optic wavelength-modulated sensor for pH applications. Fiber Bragg grating (FBG) is functionalized with a stimulus-responsive hydrogel that induces a strain on FBG due to mechanical expansion of the gel in response to ambient pH changes. The gel is synthesized from the blends of poly (vinyl alcohol)/poly (acrylic acid). The induced strain results in a shift of FBG reflected peak that is monitored by an interrogator. The sensor system shows good linearity in the acidic pH range of 3 to 7 with a sensitivity of 12.16 pm/pH. In addition, it shows good repeatability and oscillator behavior, which proves it to be fit for pH sensing applications.

  20. The Seasonal Cycle of Carbon in the Southern Pacific Ocean Observed from Biogeochemical Profiling Floats

    Science.gov (United States)

    Sarmiento, J. L.; Gray, A. R.; Johnson, K. S.; Carter, B.; Riser, S.; Talley, L. D.; Williams, N. L.

    2016-02-01

    The Southern Ocean is thought to play an important role in the ocean-atmosphere exchange of carbon dioxide and the uptake of anthropogenic carbon dioxide. However, the total number of observations of the carbonate system in this region is small and heavily biased towards the summer. Here we present 1.5 years of biogeochemical measurements, including pH, oxygen, and nitrate, collected by 11 autonomous profiling floats deployed in the Pacific sector of the Southern Ocean in April 2014. These floats sampled a variety of oceanographic regimes ranging from the seasonally ice-covered zone to the subtropical gyre. Using an algorithm trained with bottle measurements, alkalinity is estimated from salinity, temperature, and oxygen and then used together with the measured pH to calculate total carbon dioxide and pCO2 in the upper 1500 dbar. The seasonal cycle in the biogeochemical quantities is examined, and the factors governing pCO2 in the surface waters are analyzed. The mechanisms driving the seasonal cycle of carbon are further investigated by computing budgets of heat, carbon, and nitrogen in the mixed layer. Comparing the different regimes sampled by the floats demonstrates the complex and variable nature of the carbon cycle in the Southern Ocean.

  1. Data collection and analysis strategies for phMRI.

    Science.gov (United States)

    Mandeville, Joseph B; Liu, Christina H; Vanduffel, Wim; Marota, John J A; Jenkins, Bruce G

    2014-09-01

    Although functional MRI traditionally has been applied mainly to study changes in task-induced brain function, evolving acquisition methodologies and improved knowledge of signal mechanisms have increased the utility of this method for studying responses to pharmacological stimuli, a technique often dubbed "phMRI". The proliferation of higher magnetic field strengths and the use of exogenous contrast agent have boosted detection power, a critical factor for successful phMRI due to the restricted ability to average multiple stimuli within subjects. Receptor-based models of neurovascular coupling, including explicit pharmacological models incorporating receptor densities and affinities and data-driven models that incorporate weak biophysical constraints, have demonstrated compelling descriptions of phMRI signal induced by dopaminergic stimuli. This report describes phMRI acquisition and analysis methodologies, with an emphasis on data-driven analyses. As an example application, statistically efficient data-driven regressors were used to describe the biphasic response to the mu-opioid agonist remifentanil, and antagonism using dopaminergic and GABAergic ligands revealed modulation of the mesolimbic pathway. Results illustrate the power of phMRI as well as our incomplete understanding of mechanisms underlying the signal. Future directions are discussed for phMRI acquisitions in human studies, for evolving analysis methodologies, and for interpretative studies using the new generation of simultaneous PET/MRI scanners. This article is part of the Special Issue Section entitled 'Neuroimaging in Neuropharmacology'. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Forum for Almen Medicinske ph.d.-studerende

    DEFF Research Database (Denmark)

    Vedsted, Peter; Waldorff, Frans Boch; Eriksson, Tina

    Rapport fra første fællesmøde mellem nuværende og kommende almenmedicinske ph.d.-studerende. Rapporten anbefaler dannelse af et egentligt almenmedicinsk ph.d.-forum, der søges optaget i DSAM som en interessegruppe. Ph.d.-forum betragter sig som en ressource ved forskellige initiativer og ønsker...... blandt andet at arbejde for en værdig ansættelse af yngre forskere. Blandt de konkrete forslag, Ph.d.-forum har stillet, er almenmedicinske ph.d.-kurser og ph.d.-stipendium med henblik på udarbejdelse af protokol....

  3. Biochar contribution to soil pH buffer capacity

    Science.gov (United States)

    Tonutare, Tonu; Krebstein, Kadri; Utso, Maarius; Rodima, Ako; Kolli, Raimo; Shanskiy, Merrit

    2014-05-01

    Biochar as ecologically clean and stable form of carbon has complex of physical and chemical properties which make it a potentially powerful soil amendment (Mutezo, 2013). Therefore during the last decade the biochar application as soil amendment has been a matter for a great number of investigations. For the ecological viewpoint the trend of decreasing of soil organic matter in European agricultural land is a major problem. Society is faced with the task to find possibilities to stabilize or increase soil organic matter content in soil and quality. The availability of different functional groups (e.g. carboxylic, phenolic, acidic, alcoholic, amine, amide) allows soil organic matter to buffer over a wide range of soil pH values (Krull et al. 2004). Therefore the loss of soil organic matter also reduces cation exchange capacity resulting in lower nutrient retention (Kimetu et al. 2008). Biochar can retain elements in soil directly through the negative charge that develops on its surfaces, and this negative charge can buffer acidity in the soil. There are lack of investigations about the effect of biochar to soil pH buffering properties, The aim of our investigation was to investigate the changes in soil pH buffer capacity in a result of addition of carbonizated material to temperate region soils. In the experiment different kind of softwood biochars, activated carbon and different soil types with various organic matter and pH were used. The study soils were Albeluvisols, Leptosols, Cambisols, Regosols and Histosols . In the experiment the series of the soil: biochar mixtures with the biochar content 0 to 100% were used. The times of equiliberation between solid and liquid phase were from 1 to 168 hours. The suspension of soil: biochar mixtures was titrated with HCl solution. The titration curves were established and pH buffer capacities were calculated for the pH interval from 3.0 to 10.0. The results demonstrate the dependence of pH buffer capacity from soil type

  4. Results Of Analytical Sample Crosschecks For Next Generation Solvent Extraction Samples Isopar L Concentration And pH

    International Nuclear Information System (INIS)

    Peters, T.; Fink, S.

    2011-01-01

    As part of the implementation process for the Next Generation Cesium Extraction Solvent (NGCS), SRNL and F/H Lab performed a series of analytical cross-checks to ensure that the components in the NGCS solvent system do not constitute an undue analytical challenge. For measurement of entrained Isopar(reg s ign) L in aqueous solutions, both labs performed similarly with results more reliable at higher concentrations (near 50 mg/L). Low bias occurred in both labs, as seen previously for comparable blind studies for the baseline solvent system. SRNL recommends consideration to use of Teflon(trademark) caps on all sample containers used for this purpose. For pH measurements, the labs showed reasonable agreement but considerable positive bias for dilute boric acid solutions. SRNL recommends consideration of using an alternate analytical method for qualification of boric acid concentrations.

  5. Fuel cycle cost uncertainty from nuclear fuel cycle comparison

    International Nuclear Information System (INIS)

    Li, J.; McNelis, D.; Yim, M.S.

    2013-01-01

    This paper examined the uncertainty in fuel cycle cost (FCC) calculation by considering both model and parameter uncertainty. Four different fuel cycle options were compared in the analysis including the once-through cycle (OT), the DUPIC cycle, the MOX cycle and a closed fuel cycle with fast reactors (FR). The model uncertainty was addressed by using three different FCC modeling approaches with and without the time value of money consideration. The relative ratios of FCC in comparison to OT did not change much by using different modeling approaches. This observation was consistent with the results of the sensitivity study for the discount rate. Two different sets of data with uncertainty range of unit costs were used to address the parameter uncertainty of the FCC calculation. The sensitivity study showed that the dominating contributor to the total variance of FCC is the uranium price. In general, the FCC of OT was found to be the lowest followed by FR, MOX, and DUPIC. But depending on the uranium price, the FR cycle was found to have lower FCC over OT. The reprocessing cost was also found to have a major impact on FCC

  6. Ageing of rice husk biochar along a freeze-thaw cycles

    OpenAIRE

    Miao Wei; Cheng Xiao Ying; Meng Jun; Tang Liang

    2016-01-01

    In order to elucidate the aging possess of biochar, the experiment with treatment biochar with soil were performed. For accelerating aging process, freeing-thawing cycle were conducted to simulate the changing process of the physical and chemical properties of biochar and explore the roles of biochar in the changes of the soil nutrition. Aging treatment has a significant impact on the physical and chemical properties of biochar. The pH values, element composition, oxidation of the surface, ab...

  7. Survey on the Labour Market Position of PhD Graduates: Competence comparison and relation between PhD and current employment

    Energy Technology Data Exchange (ETDEWEB)

    Heuritsch, J.; Waaijer, C.J.F.; Van der Weijden, I.C.M.

    2016-07-01

    We compared the skills PhD graduates acquired during their PhDs to the ones they need in their current job. We also studied the relation between PhD topic and content of the current job of recent PhD graduates. Data was collected in a survey of 1,133 respondents with a PhD from five Dutch universities between early 2008 and mid-2012. We show that scientific skills and independence are developed sufficiently during the PhD education, whereas PhDs are lacking in management and communication skills. These competence discrepancies were compared to the educational level required for the PhD holder’s current job and the relatedness of the current job to the PhD topic. (Author)

  8. Long-term effect of tobacco on unstimulated salivary pH

    OpenAIRE

    Neeraj Grover; Jyoti Sharma; Shamindra Sengupta; Sanjeet Singh; Nishant Singh; Harjeet Kaur

    2016-01-01

    Aims and Objectives: The aim of this study was to analyze and compare the effects of tobacco on salivary pH between tobacco chewers, smokers and controls. Materials and Methods: A total of 60 subjects (males and females) aged 25-40 years, were divided equally into three groups: Tobacco smokers (Group A), chewers (Group B) and controls (Group C). Saliva of each subject was collected under resting condition. Salivary pH was determined using the specific salivary pH meter. Results: The mean (±st...

  9. PhD supervisor-student relationship

    Directory of Open Access Journals (Sweden)

    FILIPE PRAZERES

    2017-10-01

    Full Text Available The relationship between the PhD supervisor and the PhD student is a complex one. When this relationship is neither effective nor efficient, it may yield negative consequences, such as academic failure (1. The intricacy of the supervisor-student relationship may be in part comparable to the one between the physician and his/her patient [see, for example (2]. Both interactions develop over several years and the players involved in each relationship – PhD supervisor-student on the one side and physician-patient on the other side – may at some point of the journey develop different expectations of one another [see, for example (3, 4] and experience emotional distress (5. In both relationships, the perceived satisfaction with the interaction will contribute to the success or failure of the treatment in one case, and in the other, the writing of a thesis. To improve the mentioned satisfaction, not only there is a need to invest time (6, as does the physician to his/ her patients, but also both the supervisor and the PhD student must be willing to negotiate a research path to follow that would be practical and achievable. The communication between the physician and patient is of paramount importance for the provision of health care (7, and so is the communication between the supervisor and PhD student which encourages the progression of both the research and the doctoral study (8. As to a smooth transition to the postgraduate life, supervisors should start thinking about providing the same kind of positive reinforcement that every student is used to experience in the undergraduate course. The recognition for a job well done will mean a lot for a PhD student, as it does for a patient. One good example is the increase in medication compliance by patients with high blood pressure who receive positive reinforcement from their physicians (9. Supervisors can organize regular meetings for (and with PhD students in order to not only discuss their projects

  10. Obsessive-compulsive disorder and female reproductive cycle events: results from the OCD and reproduction collaborative study.

    Science.gov (United States)

    Guglielmi, Valeria; Vulink, Nienke C C; Denys, Damiaan; Wang, Ying; Samuels, Jack F; Nestadt, Gerald

    2014-12-01

    Women with obsessive-compulsive disorder (OCD) often report that symptoms first appear or exacerbate during reproductive cycle events; however, little is known about these relationships. The goals of this study were to examine, in a US and a European female OCD sample, onset and exacerbation of OCD in reproductive cycle events, and to investigate the likelihood of repeat exacerbation in subsequent pregnancies and postpartum periods. Five hundred forty-two women (United States, n = 352; Dutch, n = 190) who met DSM-IV criteria for OCD, completed self-report questionnaires designed to assess OCD onset and symptom exacerbation associated with reproductive events. OCD onset occurred within 12 months after menarche in 13.0%, during pregnancy in 5.1%, at postpartum in 4.7%, and at menopause in 3.7%. Worsening of pre-existing OCD was reported by 37.6% of women at premenstruum, 33.0% during pregnancy, 46.6% postpartum, and 32.7% at menopause. Exacerbation in first pregnancy was significantly associated with exacerbation in second pregnancy (OR = 10.82, 95% CI 4.48-26.16), as was exacerbation in first postpartum with exacerbation in second postpartum (OR = 6.86, 95% CI 3.27-14.36). Results were replicated in both samples. Reproductive cycle events are periods of increased risk for onset and exacerbation of OCD in women. The present study is the first to provide significant evidence that exacerbation in or after first pregnancy is a substantial risk factor for exacerbation in or after a subsequent pregnancy. Further research is needed to identify factors related to exacerbation, so that physicians may provide appropriate recommendations to women regarding clinical issues involving OCD and reproductive cycle events. © 2014 Wiley Periodicals, Inc.

  11. Correlation of transmissive fractures in pilot holes ONK-PH8 - PH12 and fracture traces mapped in ONKALO

    International Nuclear Information System (INIS)

    Palmen, J.; Nummela, J.; Ahokas, H.

    2014-05-01

    In a preceding study Posiva flow logging (PFL) with a 0.5 m test interval and 0.1 m steps has been used together with optical drillhole images and core logging fracture data for the exact determination of the depth of hydraulically conductive fractures in pilot holes. The fracture traces have been mapped from the ONKALO tunnel walls as a part of the systematic mapping. The mapping results has been digitized to a 3D tunnel layout in Surpac programme. The data integrity and fracture trace uniqueness has been verified by Datactica Oy and further collected to a database (RakokantaDatacticaPosiva20100607.mdb). Fractures mapped with leakage attribute have been defined as flowing, dripping, wet, or damp where the attribute is recorded. The fractures with no leakage attribute value appear to be non leaking. The water leaking surfaces on the ONKALO tunnel walls have been mapped sequentially and conclusively (once or twice a year) as a part of the Olkiluoto monitoring program (OMO) using an equal five step measure as used with fracture traces in systematic mapping. The PFL results correlated with core logging fracture data from the pilot holes ONK-PH8 - ONK-PH12 were in this work further correlated with the fractures mapped from the ONKALO tunnel walls. Each hydraulically conductive fracture of ONK-PH8 - ONK-PH12 was investigated and linked to ONKALO fracture of a coherent orientation and matching location, where such fracture trace was available. Also tunnel crosscutting fracture (TCF) data was used in combining, since the systematic mapping data was not yet available for the pilot holes ONK-PH11 and ONK-PH12 at the time of the evaluation. The main objective of the work was to identify the ONKALO fractures which correspond to the flow from fracture(s) identified with the PFL method in pilot holes and to collect basic information about the occurrence, frequency and orientation of water bearing fractures along the ONKALO tunnel. The correlated hydraulically conductive

  12. Correlation of transmissive fractures in pilot holes ONK-PH8 - PH12 and fracture traces mapped in ONKALO

    Energy Technology Data Exchange (ETDEWEB)

    Palmen, J.; Nummela, J.; Ahokas, H. [Poeyry Finland Oy, Vantaa (Finland)

    2014-05-15

    In a preceding study Posiva flow logging (PFL) with a 0.5 m test interval and 0.1 m steps has been used together with optical drillhole images and core logging fracture data for the exact determination of the depth of hydraulically conductive fractures in pilot holes. The fracture traces have been mapped from the ONKALO tunnel walls as a part of the systematic mapping. The mapping results has been digitized to a 3D tunnel layout in Surpac programme. The data integrity and fracture trace uniqueness has been verified by Datactica Oy and further collected to a database (RakokantaDatacticaPosiva20100607.mdb). Fractures mapped with leakage attribute have been defined as flowing, dripping, wet, or damp where the attribute is recorded. The fractures with no leakage attribute value appear to be non leaking. The water leaking surfaces on the ONKALO tunnel walls have been mapped sequentially and conclusively (once or twice a year) as a part of the Olkiluoto monitoring program (OMO) using an equal five step measure as used with fracture traces in systematic mapping. The PFL results correlated with core logging fracture data from the pilot holes ONK-PH8 - ONK-PH12 were in this work further correlated with the fractures mapped from the ONKALO tunnel walls. Each hydraulically conductive fracture of ONK-PH8 - ONK-PH12 was investigated and linked to ONKALO fracture of a coherent orientation and matching location, where such fracture trace was available. Also tunnel crosscutting fracture (TCF) data was used in combining, since the systematic mapping data was not yet available for the pilot holes ONK-PH11 and ONK-PH12 at the time of the evaluation. The main objective of the work was to identify the ONKALO fractures which correspond to the flow from fracture(s) identified with the PFL method in pilot holes and to collect basic information about the occurrence, frequency and orientation of water bearing fractures along the ONKALO tunnel. The correlated hydraulically conductive

  13. Biomedical PhD education - an international perspective

    DEFF Research Database (Denmark)

    Mulvany, Michael J.

    2013-01-01

    The PhD, otherwise known as the doctor of philosophy or Dr. Phil., is an internationally recognized degree, indicating that the PhD graduate has received training in research under supervision. Traditionally, the PhD was the route to an academic career, with most successful PhD graduates receiving...... tenured university positions. However, over the past 20–30 years, and particularly the past 10 years, the situation has changed dramatically. Governments in many countries have invested massively in PhD education, believing that trained researchers will contribute to the ‘knowledge society’, and thus...... increase the competitiveness of their countries in the future economies of the world. Thus, only a small fraction of PhD graduates now end up in academic research. Yet, the PhD remains a research degree, and indeed, institutions have become heavily dependent on PhD students for their research output...

  14. Solid phase synthesis and biological evaluation of enantiomerically pure wasp toxin analogues PhTX-343 and PhTX-12

    DEFF Research Database (Denmark)

    Strømgaard, K; Bjørnsdottir, I; Andersen, K

    2000-01-01

    ) of the enantiomers of PhTX-343 and PhTX-12. The methods were optimised with respect to chiral selector, buffer pH, and temperature around the capillary. Thus, rac-PhTX-343 was resolved using a separation buffer containing 30 mM heptakis-(2, 6-di-O-methyl)-beta-cyclodextrin in 50 mM 6-aminocarproic acid (pH 4. 0......) at 15 degrees C. rac-PhTX-12 was not resolvable in this system, but could be resolved using a separation buffer containing 10% w/v of dextrin 10, a linear maltodextrin, in 50 mM 6-aminocaproic acid (pH 4.0) at 15 degrees C. Using these methods, the optical purity of the synthetic enantiomers...

  15. Systemic analysis of the response of Aspergillus niger to ambient pH

    DEFF Research Database (Denmark)

    Andersen, Mikael Rørdam; Lehmann, Linda Olkjær; Nielsen, Jens

    2009-01-01

    Background: The filamentous fungus Aspergillus niger is an exceptionally efficient producer of organic acids, which is one of the reasons for its relevance to industrial processes and commercial importance. While it is known that the mechanisms regulating this production are tied to the levels...... of ambient pH, the reasons and mechanisms for this are poorly understood. Methods: To cast light on the connection between extracellular pH and acid production, we integrate results from two genome-based strategies: A novel method of genome-scale modeling of the response, and transcriptome analysis across...... three levels of pH. Results: With genome scale modeling with an optimization for extracellular proton-production, it was possible to reproduce the preferred pH levels for citrate and oxalate. Transcriptome analysis and clustering expanded upon these results and allowed the identification of 162 clusters...

  16. Corrosion of glass-bonded sodalite as a function of pH and temperature

    International Nuclear Information System (INIS)

    Morss, L. R.; Stanley, M.; Tatko, C.; Ebert, W. L.

    1999-01-01

    This paper reports the results of corrosion tests with monoliths of sodalite, binder glass, and glass-bonded sodalite, a ceramic waste form (CWF) that is being developed to immobilize radioactive electrorefiner salt used to condition spent sodium-bonded nuclear fuel. These tests were performed with dilute pH-buffered solutions in the pH range of 5-10 at temperatures of 70 and 90 C. The pH dependence of the forward dissolution rates of the CWF and its components have been determined. The pH dependence of the dissolution rates of sodalite, binder glass, and glass-bonded sodalite are similar to the pH dependence of dissolution rate of borosilicate nuclear waste glasses, with a negative pH dependence in the acidic region and a positive pH dependence in the basic region. Our results on the forward dissolution rates and their temperature and pH dependence will be used as components of a waste form degradation model to predict the long-term behavior of the CWF in a nuclear waste repository

  17. A proteorhodopsin-based biohybrid light-powering pH sensor.

    Science.gov (United States)

    Rao, Siyuan; Guo, Zhibin; Liang, Dawei; Chen, Deliang; Wei, Yen; Xiang, Yan

    2013-10-14

    The biohybrid sensor is an emerging technique for multi-functional detection that utilizes the instinctive responses or interactions of biomolecules. We develop a biohybrid pH sensor by taking advantage of the pH-dependent photoelectric characteristics of proteorhodopsin (pR). The transient absorption kinetics study indicates that the photoelectric behavior of pR is attributed to the varying lifetime of the M intermediate at different environmental pH values. This pR-based biohybrid light-powering sensor with microfluidic design can achieve real-time pH detection with quick response and high sensitivity. The results of this work would shed light on pR and its potential applications.

  18. Life-cycle cost analysis of adsorption cycles for desalination

    KAUST Repository

    Thu, Kyaw

    2010-08-01

    This paper presents the thermo-economic analysis of the adsorption desalination (AD) cycle that is driven by low-temperature waste heat from exhaust of industrial processes or renewable sources. The AD cycle uses an adsorbent such as the silica gel to desalt the sea or brackish water. Based on an experimental prototype AD plant, the life-cycle cost analysis of AD plants of assorted water production capacities has been simulated and these predictions are translated into unit cost of water production. Our results show that the specific energy consumption of the AD cycle is 1.38 kWh/m3 which is the lowest ever reported. For a plant capacity of 1000 m3/d, the AD cycle offers a unit cost of $0.457/m3 as compared to more than $0.9 for the average RO plants. Besides being cost-effective, the AD cycle is also environment-friendly as it emits less CO2 emission per m3 generated, typically 85% less, by comparison to an RO process. © 2010 Desalination Publications.

  19. Results of FY 2002 of feasibility study on commercialized fast reactor cycle systems. Phase 2

    International Nuclear Information System (INIS)

    2003-06-01

    Japan Nuclear Cycle Development Institute (JNC) and Japan Atomic Power Company (JAPC, that is the representative of the electric utilities in Japan) established a new organization to develop a commercialized fast reactor (FR) cycle system on July 1, 1999 and feasibility study (F/S) was undertaken in order to determine the promising concepts and to define the necessary R and D tasks. During Phase 1 (JFY 1999 and 2000), a number of candidate concepts were screened from various options, featuring innovative technologies. In the F/S, the options were evaluated and conceptual designs were examined considering the attainable perspectives for following: 1) ensuring safety, 2) economic competitiveness to future LWRs, 3) efficient utilization of resources, 4) reduction of environmental burden and 5) enhancement of nuclear non-proliferation. The F/S should also guide the necessary R and D to commercialize FR cycle system. To begin with the study of feasible candidate concepts screened in Phase I, Phase 2 started in the plan for five years in 2001. This aims at clarifying several feasible candidate concepts and deciding the research plan after Phase 3 as taking into consideration the innovative technology. As for this plan, an interim report will be carried out in 2003 as one pause and the prospect to clarify the feasible candidates will be expected. Furthermore, after the completion of this research and investigation program, research and development activities will be carried out under a rolling plan in which reviews will be carried out approximately every five years. The objective of these R and D activities is to make a proposal regarding highly attractive and competitive FR cycle system technology that assures safety by 2015. This report summarizes the results of F/S of Phase 2 in 2002. In 2002, the second year of Phase 2, the study was advanced along with the plan which was evaluated by the committee for the Evaluation. Then, in the study of FR system and fuel cycle

  20. Campylobacter, Salmonella, and Escherichia coli on broiler carcasses subjected to a high pH scald and low pH postpick chlorine dip.

    Science.gov (United States)

    Berrang, M E; Windham, W R; Meinersmann, R J

    2011-04-01

    The objective of this study was to determine the individual and combined effects of a high pH scald and a postpick chlorine dip on bacteria present on broiler carcasses. In each of 3 replications, a flock was sampled at several sites within a commercial broiler processing plant. Carcasses were sampled by whole carcass rinse before and after treated scalding at mean pH 9.89 or control scalding at mean pH 6.88. Other carcasses from the same flock run on both the treated and control scald lines were collected and sampled before and after a chlorine dip tank operated at mean total chlorine level of 83.3 mg/kg and pH 6.04. Rinses were cultured for numbers of Campylobacter and Escherichia coli and presence or absence of Salmonella. High pH scald was more effective than standard scald to lessen the prevalence and numbers of Campylobacter on broiler carcasses; a lower prevalence was maintained through the postpick chlorine dip tank. The pH of the scald tank made no difference in numbers of E. coli recovered from broiler carcasses at any tested point on the processing line. High pH scald was not more effective than standard scald to lessen Salmonella prevalence. Furthermore, it is unclear why the postpick chlorine dip effectively lessened Salmonella prevalence on only the control scald line. Although no evidence exists that these treatments have an additive effect when used in series, each treatment shows some promise individually. Further optimization may result in more effective decontamination of broiler carcasses.

  1. Simulation of Cycle-to-Cycle Variation in Dual-Fuel Engines

    KAUST Repository

    Jaasim, Mohammed

    2017-03-13

    Standard practices of internal combustion (IC) engine experiments are to conduct the measurements of quantities averaged over a large number of cycles. Depending on the operating conditions, the cycle-to-cycle variation (CCV) of quantities, such as the indicated mean effective pressure (IMEP) are observed at different levels. Accurate prediction of CCV in IC engines is an important but challenging task. Computational fluid dynamics (CFD) simulations using high performance computing (HPC) can be used effectively to visualize such 3D spatial distributions. In the present study, a dual fuel large engine is considered, with natural gas injected into the manifold accompanied with direct injection of diesel pilot fuel to trigger ignition. Multiple engine cycles in 3D are simulated in series as in the experiments to investigate the potential of HPC based high fidelity simulations to accurately capture the cycle to cycle variation in dual fuel engines. Open cycle simulations are conducted to predict the combined effect of the stratification of fuel-air mixture, temperature and turbulence on the CCV of pressure. The predicted coefficient of variation (COV) of pressure compared to the results from closed cycle simulations and the experiments.

  2. Studies on luteinizing hormone receptors of human corpora lutea during menstrual cycle and pregnancy

    International Nuclear Information System (INIS)

    Izumi, Yasushi

    1982-01-01

    With the purpose of explicating the lifespan of human corpora lutea, using human corpora lutea of the menstrual cycle and pregnancy, binding of 125 I-LH to the 20,000g cell membrane fraction was examined. 1) Specific bindings of 125 I-LH, 125 I-HCG were demonstrated in the 20,000g cell membrane fraction. Although LH and HCG were parallel in inhibiting 125 I-LH binding, HCG was found to be more effective. FSH did not inhibit binding. 2) Binding of 125 I-LH was dependent on time, temperature, 125 I-LH concentration, amount of the cell membrane fraction protein and pH. The highest binding was seen at pH 6.0 while incubating for 60 min at 37 0 C. 3) The number of LH receptors in human corpora lutea of the menstrual cycle increased towards midluteal phase, especiallt on 5th day from ovulation, and decreased towards late luteal phase. LH receptor was not found in corpus albicans. The apparent dissociation constant of each corpus luteum did not change throughout the menstrual cycle. 4) Corpora lutea of pregnancy contained a few or no receptors which bound 125 I-LH specifically. These data suggest that LH receptor is an important factor regulating the lifespan of corpus luteum and exogenous HCG has effect on luteal insufficiency, but the effect of HCG on threatened abortion is uncertain. (author)

  3. Influence of extracellular pH on growth, viability, cell size, acidification activity, and intracellular pH of Lactococcus lactis in batch fermentations.

    Science.gov (United States)

    Hansen, Gunda; Johansen, Claus Lindvald; Marten, Gunvor; Wilmes, Jacqueline; Jespersen, Lene; Arneborg, Nils

    2016-07-01

    In this study, we investigated the influence of three extracellular pH (pHex) values (i.e., 5.5, 6.5, and 7.5) on the growth, viability, cell size, acidification activity in milk, and intracellular pH (pHi) of Lactococcus lactis subsp. lactis DGCC1212 during pH-controlled batch fermentations. A universal parameter (e.g., linked to pHi) for the description or prediction of viability, specific acidification activity, or growth behavior at a given pHex was not identified. We found viability as determined by flow cytometry to remain high during all growth phases and irrespectively of the pH set point. Furthermore, regardless of the pHex, the acidification activity per cell decreased over time which seemed to be linked to cell shrinkage. Flow cytometric pHi determination demonstrated an increase of the averaged pHi level for higher pH set points, while the pH gradient (pHi-pHex) and the extent of pHi heterogeneity decreased. Cells maintained positive pH gradients at a low pHex of 5.5 and even during substrate limitation at the more widely used pHex 6.5. Moreover, the strain proved able to grow despite small negative or even absent pH gradients at a high pHex of 7.5. The larger pHi heterogeneity at pHex 5.5 and 6.5 was associated with more stressful conditions resulting, e.g., from higher concentrations of non-dissociated lactic acid, while the low pHi heterogeneity at pHex 7.5 most probably corresponded to lower concentrations of non-dissociated lactic acid which facilitated the cells to reach the highest maximum active cell counts of the three pH set points.

  4. In-vitro investigations of a pH- and ionic-strength-responsive polyelectrolytic hydrogel using a piezoresistive microsensor

    Science.gov (United States)

    Schulz, Volker; Guenther, Margarita; Gerlach, Gerald; Magda, Jules J.; Tathireddy, Prashant; Rieth, Loren; Solzbacher, Florian

    2010-01-01

    Environmental responsive or smart hydrogels show a volume phase transition due to changes of external stimuli such as pH or ionic strength of an ambient solution. Thus, they are able to convert reversibly chemical energy into mechanical energy and therefore they are suitable as sensitive material for integration in biochemical microsensors and MEMS devices. In this work, micro-fabricated silicon pressure sensor chips with integrated piezoresistors were used as transducers for the conversion of mechanical work into an appropriate electrical output signal due to the deflection of a thin silicon bending plate. Within this work two different sensor designs have been studied. The biocompatible poly(hydroxypropyl methacrylate-N,N-dimethylaminoethyl methacrylate-tetra-ethyleneglycol dimethacrylate) (HPMA-DMA-TEGDMA) was used as an environmental sensitive element in piezoresistive biochemical sensors. This polyelectrolytic hydrogel shows a very sharp volume phase transition at pH values below about 7.4 which is in the range of the physiological pH. The sensor's characteristic response was measured in-vitro for changes in pH of PBS buffer solution at fixed ionic strength. The experimental data was applied to the Hill equation and the sensor sensitivity as a function of pH was calculated out of it. The time-dependent sensor response was measured for small changes in pH, whereas different time constants have been observed. The same sensor principal was used for sensing of ionic strength. The time-dependent electrical sensor signal of both sensors was measured for variations in ionic strength at fixed pH value using PBS buffer solution. Both sensor types showed an asymmetric swelling behavior between the swelling and the deswelling cycle as well as different time constants, which was attributed to the different nature of mechanical hydrogel-confinement inside the sensor. PMID:21152365

  5. Excess glycogen does not resolve high ultimate pH of oxidative muscle.

    Science.gov (United States)

    England, Eric M; Matarneh, Sulaiman K; Oliver, Emily M; Apaoblaza, Ariel; Scheffler, Tracy L; Shi, Hao; Gerrard, David E

    2016-04-01

    Skeletal muscle glycogen content can impact the extent of postmortem pH decline. Compared to glycolytic muscles, oxidative muscles contain lower glycogen levels antemortem which may contribute to the higher ultimate pH. In an effort to explore further the participation of glycogen in postmortem metabolism, we postulated that increasing the availability of glycogen would drive additional pH decline in oxidative muscles to equivalent pH values similar to the ultimate pH of glycolytic muscles. Glycolysis and pH declines were compared in porcine longissimus lumborum (glycolytic) and masseter (oxidative) muscles using an in vitro system in the presence of excess glycogen. The ultimate pH of the system containing longissimus lumborum reached a value similar to that observed in intact muscle. The pH decline of the system containing masseter samples stopped prematurely resulting in a higher ultimate pH which was similar to that of intact masseter muscle. To investigate further, we titrated powdered longissimus lumborum and masseter samples in the reaction buffer. As the percentage of glycolytic sample increased, the ultimate pH decreased. These data show that oxidative muscle produces meat with a high ultimate pH regardless of glycogen content and suggest that inherent muscle factors associated with glycolytic muscle control the extent of pH decline in pig muscles. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Endoscopic sensing of alveolar pH.

    Science.gov (United States)

    Choudhury, D; Tanner, M G; McAughtrie, S; Yu, F; Mills, B; Choudhary, T R; Seth, S; Craven, T H; Stone, J M; Mati, I K; Campbell, C J; Bradley, M; Williams, C K I; Dhaliwal, K; Birks, T A; Thomson, R R

    2017-01-01

    Previously unobtainable measurements of alveolar pH were obtained using an endoscope-deployable optrode. The pH sensing was achieved using functionalized gold nanoshell sensors and surface enhanced Raman spectroscopy (SERS). The optrode consisted of an asymmetric dual-core optical fiber designed for spatially separating the optical pump delivery and signal collection, in order to circumvent the unwanted Raman signal generated within the fiber. Using this approach, we demonstrate a ~100-fold increase in SERS signal-to-fiber background ratio, and demonstrate multiple site pH sensing with a measurement accuracy of ± 0.07 pH units in the respiratory acini of an ex vivo ovine lung model. We also demonstrate that alveolar pH changes in response to ventilation.

  7. Characterisation and deployment of an immobilised pH sensor spot towards surface ocean pH measurements.

    Science.gov (United States)

    Clarke, Jennifer S; Achterberg, Eric P; Rérolle, Victoire M C; Abi Kaed Bey, Samer; Floquet, Cedric F A; Mowlem, Matthew C

    2015-10-15

    The oceans are a major sink for anthropogenic atmospheric carbon dioxide, and the uptake causes changes to the marine carbonate system and has wide ranging effects on flora and fauna. It is crucial to develop analytical systems that allow us to follow the increase in oceanic pCO2 and corresponding reduction in pH. Miniaturised sensor systems using immobilised fluorescence indicator spots are attractive for this purpose because of their simple design and low power requirements. The technology is increasingly used for oceanic dissolved oxygen measurements. We present a detailed method on the use of immobilised fluorescence indicator spots to determine pH in ocean waters across the pH range 7.6-8.2. We characterised temperature (-0.046 pH/°C from 5 to 25 °C) and salinity dependences (-0.01 pH/psu over 5-35), and performed a preliminary investigation into the influence of chlorophyll on the pH measurement. The apparent pKa of the sensor spots was 6.93 at 20 °C. A drift of 0.00014 R (ca. 0.0004 pH, at 25 °C, salinity 35) was observed over a 3 day period in a laboratory based drift experiment. We achieved a precision of 0.0074 pH units, and observed a drift of 0.06 pH units during a test deployment of 5 week duration in the Southern Ocean as an underway surface ocean sensor, which was corrected for using certified reference materials. The temperature and salinity dependences were accounted for with the algorithm, R=0.00034-0.17·pH+0.15·S(2)+0.0067·T-0.0084·S·1.075. This study provides a first step towards a pH optode system suitable for autonomous deployment. The use of a short duration low power illumination (LED current 0.2 mA, 5 μs illumination time) improved the lifetime and precision of the spot. Further improvements to the pH indicator spot operations include regular application of certified reference materials for drift correction and cross-calibration against a spectrophotometric pH system. Desirable future developments should involve novel

  8. Transepithelial SCFA fluxes link intracellular and extracellular pH regulation of mouse colonocytes.

    Science.gov (United States)

    Chu, S; Montrose, M H

    1997-10-01

    We have studied pH regulation in both intracellular and extracellular compartments of mouse colonic crypts, using distal colonic mucosa with intact epithelial architecture. In this work, we question how transepithelial SCFA gradients affect intracellular pH (pHi) and examine interactions between extracellular pH (pHo) and pHi regulation in crypts of distal colonic epithelium from mouse. We studied pH regulation in three adjacent compartments of distal colonic epithelium (crypt lumen, crypt epithelial cell cytosol, and lamina propria) with SNARF-1 (a pH sensitive fluorescent dye), digital imaging microscopy (for pHi), and confocal microscopy (for pHo). Combining results from the three compartments allows us to find how pHi and pHo are regulated and related under the influence of physiological transepithelial SCFA gradients, and develop a better understanding of pH regulation mechanisms in colonic crypts. Results suggest a complex interdependency between SCFA fluxes and pHo values, which can directly affect how strongly SCFAs acidify colonocytes.

  9. A Busy period analysis of the level dependent PH/PH/1/K queue

    NARCIS (Netherlands)

    Al Hanbali, Ahmad

    2011-01-01

    In this paper, we study the transient behavior of a level dependent single server queuing system with a waiting room of finite size during the busy period. The focus is on the level dependent PH/PH/1/K queue. We derive in closed form the joint transform of the length of the busy period, the number

  10. Disturbances in closed water cycle papermaking; Vaehaevetisen paperinvalmistuksen haeirioetekijaet - MPKY 01

    Energy Technology Data Exchange (ETDEWEB)

    Nyblom, I.; Asikainen, J.; Salerma, M.; Schlupp, K. [Finnish Pulp and Paper Research Institute, Espoo (Finland)

    1998-12-31

    There are fears that reducing water consumption at paper mills will make the papermaking process more susceptible to disturbances. Substances accumulating in the circulating water will give rise to fouling and precipitates as well as flaws in the paper web. A wet end simulator, to be built at KCL (The Finnish Pulp and Paper Research Institute) this year, will be used to test water cycle closure equivalent to a specific water consumption of 3-4 m{sup 3}/t of pulp. The first part of the investigation will examine fouling and precipitate formation due to temperature and pH disturbances. In the second part, tests will be made on the use of on-line measuring instruments in contaminated water cycles. (orig.)

  11. Disturbances in closed water cycle papermaking; Vaehaevetisen paperinvalmistuksen haeirioetekijaet - MPKY 01

    Energy Technology Data Exchange (ETDEWEB)

    Nyblom, I; Asikainen, J; Salerma, M; Schlupp, K [Finnish Pulp and Paper Research Institute, Espoo (Finland)

    1999-12-31

    There are fears that reducing water consumption at paper mills will make the papermaking process more susceptible to disturbances. Substances accumulating in the circulating water will give rise to fouling and precipitates as well as flaws in the paper web. A wet end simulator, to be built at KCL (The Finnish Pulp and Paper Research Institute) this year, will be used to test water cycle closure equivalent to a specific water consumption of 3-4 m{sup 3}/t of pulp. The first part of the investigation will examine fouling and precipitate formation due to temperature and pH disturbances. In the second part, tests will be made on the use of on-line measuring instruments in contaminated water cycles. (orig.)

  12. Conformational changes in Sindbis virions resulting from exposure to low pH and interactions with cells suggest that cell penetration may occur at the cell surface in the absence of membrane fusion

    International Nuclear Information System (INIS)

    Paredes, Angel M.; Ferreira, Davis; Horton, Michelle; Saad, Ali; Tsuruta, Hiro; Johnston, Robert; Klimstra, William; Ryman, Kate; Hernandez, Raquel; Chiu Wah; Brown, Dennis T.

    2004-01-01

    Alphaviruses have the ability to induce cell-cell fusion after exposure to acid pH. This observation has served as an article of proof that these membrane-containing viruses infect cells by fusion of the virus membrane with a host cell membrane upon exposure to acid pH after incorporation into a cell endosome. We have investigated the requirements for the induction of virus-mediated, low pH-induced cell-cell fusion and cell-virus fusion. We have correlated the pH requirements for this process to structural changes they produce in the virus by electron cryo-microscopy. We found that exposure to acid pH was required to establish conditions for membrane fusion but that membrane fusion did not occur until return to neutral pH. Electron cryo-microscopy revealed dramatic changes in the structure of the virion as it was moved to acid pH and then returned to neutral pH. None of these treatments resulted in the disassembly of the virus protein icosahedral shell that is a requisite for the process of virus membrane-cell membrane fusion. The appearance of a prominent protruding structure upon exposure to acid pH and its disappearance upon return to neutral pH suggested that the production of a 'pore'-like structure at the fivefold axis may facilitate cell penetration as has been proposed for polio (J. Virol. 74 (2000) 1342) and human rhino virus (Mol. Cell 10 (2002) 317). This transient structural change also provided an explanation for how membrane fusion occurs after return to neutral pH. Examination of virus-cell complexes at neutral pH supported the contention that infection occurs at the cell surface at neutral pH by the production of a virus structure that breaches the plasma membrane bilayer. These data suggest an alternative route of infection for Sindbis virus that occurs by a process that does not involve membrane fusion and does not require disassembly of the virus protein shell

  13. Atividade alelopática de substâncias químicas isoladas da Acacia mangium e suas variações em função do PH Allelopathic activity of chemical substances isolated from Acacia mangium and its variations in function of PH

    Directory of Open Access Journals (Sweden)

    S.M. Luz

    2010-01-01

    bioassays (at 25 oC and under 12-12 h light-dark cycle and radicle and hypocotyl development (at 25 oC and under 24-24 h light-dark cycle of the weed species malicia (Mimosa pudica and mata-pasto (Senna obtusifolia. The influence of the pH (3.0 and 9.0 of the solution in the allelopathic activity of the substances on seed germination of the same species was evaluated. The triterpenoids Lupenone (3 oxolup-20(29-ene and Lupeol (3β-hydroxylup-20(29-ene, obtained from fallen leaves of the donor plant, separately and in pair, showed low allelopathic effects on seed germination and hypocotyl growth, especially on the former, with effects showing values lower than 2%. The effects on radicle growth were higher than the other two, reaching values above 40%, especially inhibition promoted by the substance Lupenone. Separately, each substance showed higher effects than those observed when tested in pair, indicating the existence of antagonism. The pH of the solution influenced the allelopathic activity of the substances; for Lupenone, the effects were more intense at acidic pH, while for Lupeol, best results were observed under alkaline conditions, showing that this is an important factor to be considered in field works.

  14. Life-cycle assessment of photovoltaic systems: results of Swiss studies on energy chains

    Energy Technology Data Exchange (ETDEWEB)

    Dones, Roberto [Paul Scherrer Inst., Villigen (Switzerland); Frischknecht, Rolf [Federal Institute of Technology, Zurich (Switzerland)

    1998-04-01

    The methodology used and results obtained for grid-connected photovoltaic (PV) plants in recent Swiss life-cycle assessment (LCA) studies on current and future energy systems are discussed. Mono- and polycrystalline silicon cell technologies utilised in current panels as well as monocrystalline and amorphous cells for future applications were analysed from Swiss conditions. The environmental inventories of slanted-roof solar panels and large plants are presented. Greenhouse gas emissions from present and future electricity systems are compared. The high electricity requirements for manufacturing determine most of the environmental burdens associated with current photovoltaics. However, due to increasing efficiency of production processes and cells, the environmental performance of PV systems is likely to improve substantially in the future. (Author)

  15. Life-cycle assessment of photovoltaic systems: results of Swiss studies on energy chains

    International Nuclear Information System (INIS)

    Dones, Roberto; Frischknecht, Rolf

    1998-01-01

    The methodology used and results obtained for grid-connected photovoltaic (PV) plants in recent Swiss life-cycle assessment (LCA) studies on current and future energy systems are discussed. Mono- and polycrystalline silicon cell technologies utilised in current panels as well as monocrystalline and amorphous cells for future applications were analysed from Swiss conditions. The environmental inventories of slanted-roof solar panels and large plants are presented. Greenhouse gas emissions from present and future electricity systems are compared. The high electricity requirements for manufacturing determine most of the environmental burdens associated with current photovoltaics. However, due to increasing efficiency of production processes and cells, the environmental performance of PV systems is likely to improve substantially in the future. (Author)

  16. Predicting and measurement of pH of seawater reverse osmosis concentrates

    KAUST Repository

    Waly, Tarek; Kennedy, Maria Dolores; Witkamp, Geert-Jan; Amy, Gary L.; Schippers, Jan Cornelis

    2011-01-01

    The pH of seawater reverse osmosis plants (SWRO) is the most influential parameter in determining the degree of supersaturation of CaCO3 in the concentrate stream. For this, the results of pH measurements of the concentrate of a seawater reverse

  17. Acid loading test (pH)

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003615.htm Acid loading test (pH) To use the sharing features on this page, please enable JavaScript. The acid loading test (pH) measures the ability of the ...

  18. Benefits of cycle stretchout in pressurized water reactor extended-burnup fuel cycles

    International Nuclear Information System (INIS)

    Matzie, R.A.; Leung, D.C.; Liu, Y.; Beekmann, R.W.

    1981-01-01

    Nuclear reactors are inherently capable of operating for a substantial period beyond their nominal end of cycle (EOC) as a result of negative moderator and fuel temperature coefficients and the decrease in xenon poisoning with lower core power levels. This inherent capability can be used to advantage to reduce annual uranium makeup requirements and cycle energy costs by the use of planned EOC stretchout. This paper discusses the fuel utilization efficiency and economics of both the five-batch, extended-burnup cycle and the three-batch, standard-burnup cycle, which can be improved by employing planned EOC (end of cycle) stretchout. 11 refs

  19. PhD students and integrative research

    NARCIS (Netherlands)

    Fry, G.; Tress, B.; Tress, G.

    2006-01-01

    The training of PhD students is currently very dynamic and varies widely from place to place. We present some examples of this variation and comment on how it may affect the way PhD students cope with integrative studies. Our focus is on the training needs of PhD students studying integrative

  20. Effect of pH on saturated hydraulic conductivity and soil dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Suarez, D.L.; Roades, J.D.; Lavado, R.; Grieve, C.M.

    The adverse effects of exchangeable sodium on soil hydraulic conductivity (K) are well known, but at present only sodicity and total electrolyte concentration are used in evaluating irrigation water suitability. In arid areas, high sodicity is often associatd with high dissolved carbonate and thus high pH, but in humid areas high sodicity may be associated with low pH. To evaluate the effect of pH (as an independent variable) on K, solutions with the same SAR and electrolyte level were prepared at pH 6, 7, 8, and 9. Saturated K values were determined at constant flux in columns packed at a bulk density of 1.5 Mg m/sup -3/. At pH 9, saturated K values were lower than at pH 6 for a montmorillonitic and kaolinitic soil. For a vermiculitic soil with lower organic carbon and higher silt content, pH changes did not cause large K differences. Decreases in K were not reversible on application of waters with higher electrolyte levels. The results from the K experiments were generally consistent with optical transmission measurements of dispersion. Although anion adsorption was at or below detection limits and cation exchange capacity (CEC) was only slightly dependent on pH, differences in pH effects on K among soils are likely due to differences in quantities of variable-charge minerals and organic matter.

  1. Control of pH of retained water in the coastal waste disposal site

    Directory of Open Access Journals (Sweden)

    Hem Ramrav

    2018-01-01

    Full Text Available After landfilling of wastes is completed, the stabilization of landfilled ground requires much time and cost. Therefore, this study aimed to control the pH of retained water in the coastal waste disposal sites during landfilling process, by conducting field surveys and laboratory experiments. In field surveys, we investigated the changes of retained water quality such as pH, salinity, and dissolved oxygen. The results show the pH of retained water has risen to about 10 when the volume of landfilled wastes reached about 25% of landfill capacity. In lowing the pH, we considered a low-cost method by pumping seawater from the adjacent sea into the landfill. The mechanism in this method is that, H+ dissociated from HCO3- in the fresh seawater react with OH- eluted from wastes would result in pH decrease. The laboratory experiments were conducted to verify the effect on pH change by adding fresh seawater to alkalized seawater. As a result, the effect of injecting fresh seawater into alkalized seawater with pH higher than 9 was confirmed. Therefore, this treatment method is suggested to enable the disposal sites to be used promptly after landfilling is completed, by adding fresh seawater to purify the retained water and waste at low cost during landfilling process.

  2. Fetal scalp pH testing

    Science.gov (United States)

    Fetal scalp blood; Scalp pH testing; Fetal blood testing - scalp; Fetal distress - fetal scalp testing; Labor - fetal scalp testing ... a baby. In these cases, testing the scalp pH can help the doctor decide whether the fetus ...

  3. Cycling in Sydney, Australia

    Directory of Open Access Journals (Sweden)

    Alexis Zander

    2013-01-01

    Full Text Available Introduction. Cycling can be an enjoyable way to meet physical activity recommendations and is suitable for older people; however cycling participation by older Australians is low. This qualitative study explored motivators, enablers, and barriers to cycling among older people through an age-targeted cycling promotion program. Methods. Seventeen adults who aged 50–75 years participated in a 12-week cycling promotion program which included a cycling skills course, mentor, and resource pack. Semistructured interviews at the beginning and end of the program explored motivators, enablers, and barriers to cycling. Results. Fitness and recreation were the primary motivators for cycling. The biggest barrier was fear of cars and traffic, and the cycling skills course was the most important enabler for improving participants’ confidence. Reported outcomes from cycling included improved quality of life (better mental health, social benefit, and empowerment and improved physical health. Conclusions. A simple cycling program increased cycling participation among older people. This work confirms the importance of improving confidence in this age group through a skills course, mentors, and maps and highlights additional strategies for promoting cycling, such as ongoing improvement to infrastructure and advertising.

  4. Variability of O2, H2S, and pH in intertidal sediments measured on a highly resolved spatial and temporal scale

    Science.gov (United States)

    Walpersdorf, E.; Werner, U.; Bird, P.; de Beer, D.

    2003-04-01

    We investigated the variability of O_2, pH, and H_2S in intertidal sediments to assess the time- and spatial scales of changes in environmental conditions and their effects on bacterial activities. Measurements were performed over the tidal cycle and at different seasons by the use of microsensors attached to an autonomous in-situ measuring device. This study was carried out at a sand- and a mixed flat in the backbarrier area of Spiekeroog (Germany) within the frame of the DFG research group "Biogeochemistry of the Wadden Sea". Results showed that O_2 variability was not pronounced in the coastal mixed flat, where only extreme weather conditions could increase O_2 penetration. In contrast, strong dynamics in O_2 availability, pH and maximum penetration depths of several cm were found at the sandflat. In these highly permeable sediments, we directly observed tidal pumping: at high tide O_2-rich water was forced into the plate and at low tide anoxic porewater drained off the sediment. From the lower part of the plate where organic rich clayey layers were embedded in the sediment anoxic water containing H_2S leaked out during low tide. Thus advective processes, driven by the tidal pump, waves and currents, control O_2 penetration and depth distribution of H_2S and pH. The effects of the resulting porewater exchange on mineralization rates and microbial activities will be discussed.

  5. KOH concentration effect on cycle life of nickel-hydrogen cells. III - Cycle life test

    Science.gov (United States)

    Lim, H. S.; Verzwyvelt, S. A.

    1988-01-01

    A cycle life test of Ni/H2 cells containing electrolytes of various KOH concentrations and a sintered type nickel electrode was carried out at 23 C using a 45 min accelerated low earth orbit (LEO) cycle regime at 80 percent depth of discharge. One of three cells containing 26 percent KOH has achieved over 28,000 cycles, and the other two 19,000 cycles, without a sign of failure. Two other cells containing 31 percent KOH electrolyte, which is the concentration presently used in aerospace cells, failed after 2,979 and 3,620 cycles. This result indicates that the cycle life of the present type of Ni/H2 cells may be extended by a factor of 5 to 10 simply by lowering the KOH concentration. Long cycle life of a Ni/H2 battery at high depth-of-discharge operation is desired, particularly for an LEO spacecraft application. Typically, battery life of about 30,000 cycles is required for a five year mission in an LEO. Such a cycle life with presently available cells can be assured only at a very low depth-of-discharge operation. Results of testing already show that the cycle life of an Ni/H2 cell is tremendously improved by simply using an electrolyte of low KOH concentration.

  6. Unexpected results from direct measurement, with a torsion microbalance in a closed system, of calcification rates of the coral Agaricia agaricites (Scleractinia:Agariicidae and concomitant changes in seawater pH

    Directory of Open Access Journals (Sweden)

    Ian M. Sandeman

    2014-09-01

    Full Text Available Ocean acidification is impacting the calcification of corals, but the mechanisms of calcification are still unclear. To explore the relationship between calcification and pH, small pieces of coral were suspended from a torsion microbalance in gently stirred, temperature controlled, seawater in a closed chamber. Net calcification rate and pH were continuously monitored while light, temperature or pH could be manipulated. The coral pieces were from the edges of thin plates of Agaricia agaricites and were studied alive and freshly collected. Unexpectedly, when calcification was taking place (n=9, 0.082 mg.hr-1.cm-2, as determined by weight increase, the pH of the surrounding seawater medium changed little (n=10, -0.0047 pH units.hr-1.cm-2. When calcification was not taking place the decrease of seawater pH was an order of magnitude higher, -0.013 pH units.hr-1.cm-2. This is the opposite of what is expected when calcium carbonate (CaCO3 forms. Similarly, fresh skeleton initially showed no change of pH in the seawater medium although the rates of weight gain were high (upto 1.0 mg hr-1.cm-2. After 10 hours, as the rate of deposition decreased following a generalized Michaelis-Menten growth curve, the pH began to decrease dramatically indicating an increase of CO2 in the seawater. These unexpected results can be explained if unstable calcium bicarbonate (Ca(HCO³2 is formed in the organic matrix/carbonic anhydrase surface and slowly transforms later to CaCO3. Pieces of living coral monitored in the chamber for 30 hours gained weight during the day and loss it at night. The loss would be consistent with the transformation of Ca(HCO³2 to CaCO3 with the release of CO2. The mean calcification rate of live coral was greater (n=8, p=0.0027 in high light (120 μmol.s-1.m-2 at 0.098 mg.hr-1.cm-2, compared to 0.063 mg.hr-1.cm-2 in low light (12 μmol.s-1.m-2. However, at the same time the mean rate of pH change was -0.0076 under low light compared to -0

  7. CONTINUOUS MEASUREMENT OF THE CYTOPLASMIC PH IN LACTOCOCCUS-LACTIS WITH A FLUORESCENT PH INDICATOR

    NARCIS (Netherlands)

    MOLENAAR, D; ABEE, T; KONINGS, WN

    1991-01-01

    The cytoplasmic pH of Lactococcus lactis was studied with the fluorescent pH indicator 2',7'-bis-(2-carboxyethyl)-5 (and-6)-carboxyfluorescein (BCECF). A novel method was applied for loading bacterial cells with BCECF, which consists of briefly treating a dense cell suspension with acid in the

  8. Determination of Peroxisomal pH in Living Mammalian Cells Using pHRed.

    Science.gov (United States)

    Godinho, Luis F; Schrader, Michael

    2017-01-01

    Organelle pH homeostasis is crucial for maintaining proper cellular function. The nature of the peroxisomal pH remains somewhat controversial, with several studies reporting conflicting results. Here, we describe in detail a rapid and accurate method for the measurement of peroxisomal pH, using the pHRed sensor protein and confocal microscopy of living mammalian cells. pHRed, a ratiometric sensor of pH, is targeted to the peroxisomes by virtue of a C-terminal targeting sequence. The probe has a maximum fluorescence emission at 610 nm while exhibiting dual excitation peaks at 440 and 585 nm, allowing for ratiometric imaging and determination of intracellular pH in live cell microscopy.

  9. Stability of a fiber optic pH sensor at 100 degree F

    International Nuclear Information System (INIS)

    Angel, S.M.; Northrup, M.A.

    1993-02-01

    A simple ratiometric fiber-optic pH sensor was developed and accelerated aging studies were performed in 100 degree F distilled water. A ph-sensitive fluorescent indicator dye, HPTS (hydroxypyrenetrisulfonic acid) was convalently attached, using a procedure that was developed during this work, to a polyacrylamide polymer that was subsequently immobilized at the end of an optical fiber. Different immobilization techniques were compared and it was found that physically attaching the indicator gels to the fibers gave the most reproducible long-term results. These fiber-optic sensors were found to give linear pH responses, between pH 6 and 8, and resolution greater than 0.25 pH unit with useful lifetimes exceeding one year

  10. Influence of early pH decline on calpain activity in porcine muscle

    DEFF Research Database (Denmark)

    Pomponio, Luigi; Ertbjerg, Per; Karlsson, Anders H

    2010-01-01

    myofibril fragmentation at 24 h post-mortem was observed, which was no longer evident in the later phase of the tenderization process. In conclusion, the rate of early pH decline influenced l-calpain activity and the rate but not the extent of myofibrillar degradation, suggesting an early effect......This study investigated the influence of post-mortem pH decline on calpain activity and myofibrillar degradation.From 80 pigs, 30 Longissimus dorsi (LD) muscles were selected on the basis of pH values at 3 h post-mortem and classified into groups of 10 as fast, intermediate and slow pH decline...... measured. A faster decrease in pH resulted in reduced level of l-calpain activity and increased autolysis of the enzyme, and hence an earlier loss of activity due to activation of l-calpain in muscles with a fast pH decline. Paralleling the l-calpain activation in muscles with a fast pH decline a higher...

  11. Systematic generation of buffer systems for pH gradient ion exchange chromatography and their application.

    Science.gov (United States)

    Kröner, Frieder; Hubbuch, Jürgen

    2013-04-12

    pH gradient protein separations are widely used techniques in the field of protein analytics, of which isoelectric focusing is the most well known application. The chromatographic variant, based on the formation of pH gradients in ion exchange columns is only rarely applied due to the difficulties to form controllable, linear pH gradients over a broad pH range. This work describes a method for the systematic generation of buffer compositions with linear titration curves, resulting in well controllable pH gradients. To generate buffer compositions with linear titration curves an in silico method was successfully developed. With this tool, buffer compositions for pH gradient ion exchange chromatography with pH ranges spanning up to 7.5 pH units were established and successfully validated. Subsequently, the buffer systems were used to characterize the elution behavior of 22 different model proteins in cation and anion exchange pH gradient chromatography. The results of both chromatographic modes as well as isoelectric focusing were compared to describe differences in between the methods. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. The Training and Work of Ph.D. Physical Scientists

    Science.gov (United States)

    Smith, S. J.; Schweitzer, A. E.

    2003-05-01

    Doctoral education has often been viewed as the pinnacle of the formal education system. How useful is doctoral training in one's later career? In an NSF-funded project, we set out to perform a study of the training, careers, and work activities of Ph.D. physical scientists. The study included both in-depth interviews and a survey sent out to a sample of Ph.D. holders 4-8 years after graduation. Come and find out the results of this study: What skills are most Ph.D. physical scientists using? What should graduate programs be teaching? Are Ph.D.'s who are working in their specific field of training happier than their counterparts working different jobs? What skills and preparation lead to future job satisfaction, perhaps the most important indicator of the "success" of graduate education? A preprint and further details can be found at the project web site at: spot.colorado.edu/ phdcarer.

  13. pH Sensitivity of Novel PANI/PVB/PS3 Composite Films

    Directory of Open Access Journals (Sweden)

    Olga Korostynska

    2007-12-01

    Full Text Available This paper reports on the results from the investigation into the pH sensitivity ofnovel PANI/PVB/PS3 composite films. The conductimetric sensing mode was chosen as itis one of the most promising alternatives to the mainstream pH-sensing methods and it is theleast investigated due to the popularity of other approaches. The films were deposited usingboth screen-printing and a drop-coating method. It was found that the best response to pHwas obtained from the screen-printed thick films, which demonstrated a change inconductance by as much as three orders of magnitude over the pH range pH2-pH11. Thedevices exhibited a stable response over 96 hours of operation. Several films were immersedin buffer solutions of different pH values for 96 hours and these were then investigated usingXPS. The resulting N 1s spectra for the various films confirmed that the change inconductance was due to deprotonation of the PANI polymer backbone. SEM andProfilometry were also undertaken and showed that no considerable changes in themorphology of the films took place and that the films did not swell or contract due toexposure to test solutions.

  14. Ratiometric Imaging of Extracellular pH in Dental Biofilms Using C-SNARF-4

    DEFF Research Database (Denmark)

    Dige, Irene

    pH in dental biofilms plays a central role for the development of caries lesions. For decades, pH measurements in biofilms have been limited to recording pH with electrodes/microelectrodes that do not permit monitoring horizontal pH gradients in biofilms in real-time. Quantitative fluorescent...... microscopy can overcome these problems. Objective: The aim of this demonstration study was to monitor extracellular biofilm pH microscopically with the ratiometric pH-sensitive dye C-SNARF-4 in in-situ-grown dental biofilms. Methods: Using confocal microscopy, the dye C-SNARF-4 was employed both as p...... the microscopic images in order to exclusively determine extracellular pH. We monitored the pH drop at the biofilm-substratum interface in six microscopic fields of view per biofilm for 1h after exposure to 0.4% glucose. Results: Extracellular pH dropped rapidly in all specimens. In both individuals, analysis...

  15. Iodine evolution and pH control

    International Nuclear Information System (INIS)

    Beahm, E.C.; Lorenz, R.A.; Weber, C.F.

    1993-01-01

    The pH is the major factor in determining the extent of I 2 in solution. In containment where no pH-control chemicals are present, the acidity or basicity of the water pool will be determined by materials that are introduced into containment as a result of the accident itself. These materials may be fission products (i.e., cesium compounds), thermally produced products (i.e., core-concrete aerosols), or compounds produced by radiation (i.e., nitric acid). In situations where pH levels fall below ∼7, the formation of I 2 will occur in irradiated iodide solutions. A correlation between pH and iodine formation is needed so that the amounts I 2 in water pools can be assessed. This, in turn, determines the amount of I 2 in the atmosphere available for escape by containment leakage. A number of calculational routines based on more than 100 differential equations representing individual reactions can be found in the literature. In this work, it is shown that a simpler approach based on the steady-state decomposition of hydrogen peroxide should correctly describe iodine formation in severe accidents. Comparisons with test data show this approach to be valid. The most important acids in containment will be nitric acid (HNO 3 ), produced by irradiation of water and air, and hydrochloric acid (HCl), produced by irradiation or heating of electrical cable insulation. The most important bases in containment will be cesium hydroxide, cesium borate (or cesium carbonate), and in some plants pH additives, such as sodium hydroxide or sodium phosphate

  16. (p-ClPhSe)2 stimulates carbohydrate metabolism and reverses the metabolic alterations induced by high fructose load in rats.

    Science.gov (United States)

    Quines, Caroline B; Rosa, Suzan G; Chagas, Pietro M; Velasquez, Daniela; Prado, Vinicius C; Nogueira, Cristina W

    2017-09-01

    The modern life leads to excess consumption of food rich in fructose; however, the long-term changes in carbohydrate and lipid metabolism could lead to metabolic dysfunction in humans. The present study evaluated the in vitro insulin-mimetic action of p-chloro-diphenyl diselenide (p-ClPhSe) 2 . The second aim of this study was to investigate if (p-ClPhSe) 2 reverses metabolic dysfunction induced by fructose load in Wistar rats. The insulin-mimetic action of (p-ClPhSe) 2  at concentrations of 50 and 100 μM was determined in slices of rat skeletal muscle. (p-ClPhSe) 2  at a concentration of 50 μM stimulated the glucose uptake by 40% in skeletal muscle. A dose-response curve revealed that (p-ClPhSe) 2  at a dose of 25 mg/kg reduced (∼20%) glycemia in rats treated with fructose (5 g/kg, i.g.). The administration of fructose impaired the liver homeostasis and (p-ClPhSe) 2 (25 mg/kg) protected against the increase (∼25%) in the G-6-Pase and isocitrate dehydrogenase activities and reduced the triglyceride content (∼25%) in the liver. (p-ClPhSe) 2 regulated the liver homeostasis by stimulating hexokinase activity (∼27%), regulating the TCA cycle activity (increased the ATP and citrate synthase activity (∼15%)) and increasing the glycogen levels (∼67%). In conclusion, (p-ClPhSe) 2 stimulated carbohydrate metabolism and reversed metabolic dysfunction in rats fed with fructose. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Towards control of aggregational behaviour of alpha-lactalbumin at acidic pH.

    Science.gov (United States)

    Pedersen, Jane B; Fojan, Peter; Sorensen, John; Petersen, Steffen B

    2006-07-01

    alpha-Lactalbumin (alpha-La) undergoes considerable structural changes upon loss of bound Ca2+ at acidic pH, leaving alpha-La in a molten globule structure. Using fluorescence the present work provides more insight into the structural transition of alpha-La at acidic pH leading to protein aggregation, most likely caused by a combination of hydrophobic and electrostatic interactions. The rate of aggregation is determined by the protein concentration and temperature applied. Availability of Ca2+ stabilises the protein, and thus prevent aggregation at pH values as low as pH 2.9. In contrast, presence of Cu2+ induces a destabilisation of the protein, which can be explained by a binding to the Zn2+ binding site in alpha-La, possibly resulting in structural alterations of the protein. In general, presence of anions destabilize alpha-La at pH values below pI, with SO4(2-) exhibiting the strongest effect on the protein stability, thus correlating well with the Hofmeister series. At more acidic pH values far from pI, alpha-La becomes more stable towards ion induced aggregation, since higher ion activity is required to efficiently screen the charges on the protein surface. The results presented in this paper provide detailed knowledge on the external parameters leading to aggregation of alpha-La at acidic pH, thus permitting rational design of the aggregation process.

  18. Biodiesel transesterification kinetics monitored by pH measurement.

    Science.gov (United States)

    Clark, William M; Medeiros, Nicholas J; Boyd, Donal J; Snell, Jared R

    2013-05-01

    Quantification of a pH change that was observed over the course of the transesterification reaction that converts vegetable oil to biodiesel may provide a simple method to monitor the reaction. Transesterification of canola oil at 6:1 methanol to oil ratio with 0.5 wt.% KOH as catalyst was studied at 25, 35, and 45 °C. Reaction conversion was correlated to pH measurements and the results were shown to be in agreement with an independent measure of conversion using an enzymatic assay for glycerol. Rate constants obtained from these measurements are consistent with those in the literature. The measured pH change appears to be related to dilution of OH(-) ions as the oil is converted to products rather than to depletion of OH(-) due to reaction. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Dimensional behavior of Ni-YSZ composites during redox cycling

    DEFF Research Database (Denmark)

    Pihlatie, Mikko; Kaiser, Andreas; Larsen, Peter Halvor

    2009-01-01

    The dimensional behavior of Ni-yttria-stabilized zirconia (YSZ) cermets during redox cycling was tested in dilatometry within the temperature range 600-1000 degrees C. The effect Of humidity oil redox stability was investigated at intermediate and low temperatures. We show that both the sintering...... of nickel depending on temperature of the initial reduction and the operating conditions, and the temperature of reoxidation are very important for the size of the dimensional change. Cumulative redox strain (CRS) is shown to be correlated with temperature. Measured maximum CRS after three redox cycles...... varies within 0.25-3.2% dL/L in dry gas and respective temperature range of 600-1000 degrees C. A high degree of redox reversibility was reached at low temperature. however. reversibility is lost at elevated temperatures. We found that at 850 degrees C, 6% steam and a very high p(H2O)/p(H2) ratio...

  20. Modeling pH variation in reverse osmosis.

    Science.gov (United States)

    Nir, Oded; Bishop, Noga Fridman; Lahav, Ori; Freger, Viatcheslav

    2015-12-15

    The transport of hydronium and hydroxide ions through reverse osmosis membranes constitutes a unique case of ionic species characterized by uncommonly high permeabilities. Combined with electromigration, this leads to complex behavior of permeate pH, e.g., negative rejection, as often observed for monovalent ions in nanofiltration of salt mixtures. In this work we employed a rigorous phenomenological approach combined with chemical equilibrium to describe the trans-membrane transport of hydronium and hydroxide ions along with salt transport and calculate the resulting permeate pH. Starting from the Nernst-Planck equation, a full non-linear transport equation was derived, for which an approximate solution was proposed based on the analytical solution previously developed for trace ions in a dominant salt. Using the developed approximate equation, transport coefficients were deduced from experimental results obtained using a spiral wound reverse osmosis module operated under varying permeate flux (2-11 μm/s), NaCl feed concentrations (0.04-0.18 M) and feed pH values (5.5-9.0). The approximate equation agreed well with the experimental results, corroborating the finding that diffusion and electromigration, rather than a priori neglected convection, were the major contributors to the transport of hydronium and hydroxide. The approach presented here has the potential to improve the predictive capacity of reverse osmosis transport models for acid-base species, thereby improving process design/control. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Fiber Optic pH Sensor with Self-Assembled Polymer Multilayer Nanocoatings

    OpenAIRE

    Shao, Li-Yang; Yin, Ming-Jie; Tam, Hwa-Yaw; Albert, Jacques

    2013-01-01

    A fiber-optic pH sensor based on a tilted fiber Bragg grating (TFBG) with electrostatic self-assembly multilayer sensing film is presented. The pH sensitive polymeric film, poly(diallyldimethylammonium chloride) (PDDA) and poly(acrylic acid) (PAA) was deposited on the circumference of the TFBG with the layer-by-layer (LbL) electrostatic self-assembly technique. The PDDA/PAA film exhibits a reduction in refractive index by swelling in different pH solutions. This effect results in wavelength s...

  2. Management of Stress and Anxiety Among PhD Students During Thesis Writing: A Qualitative Study.

    Science.gov (United States)

    Bazrafkan, Leila; Shokrpour, Nasrin; Yousefi, Alireza; Yamani, Nikoo

    2016-01-01

    Today, postgraduate students experience a variety of stresses and anxiety in different situations of academic cycle. Stress and anxiety have been defined as a syndrome shown by emotional exhaustion and reduced personal goal achievement. This article addresses the causes and different strategies of coping with this phenomena by PhD students at Iranian Universities of Medical Sciences. The study was conducted by a qualitative method using conventional content analysis approach. Through purposive sampling, 16 postgraduate medical sciences PhD students were selected on the basis of theoretical sampling. Data were gathered through semistructured interviews and field observations. Six hundred fifty-four initial codes were summarized and classified into 4 main categories and 11 subcategories on the thematic coding stage dependent on conceptual similarities and differences. The obtained codes were categorized under 4 themes including "thesis as a major source of stress," "supervisor relationship," "socioeconomic problem," and "coping with stress and anxiety." It was concluded that PhD students experience stress and anxiety from a variety of sources and apply different methods of coping in effective and ineffective ways. Purposeful supervision and guidance can reduce the cause of stress and anxiety; in addition, coping strategy must be in a thoughtful approach, as recommended in this study.

  3. Canonical correlation of waste glass compositions and durability, including pH

    International Nuclear Information System (INIS)

    Oeksoy, D.; Pye, L.D.; Bickford, D.F.; Ramsey, W.G.

    1993-01-01

    Control of waste glass durability is a major concern in the immobilization of radioactive and mixed wastes. Leaching rate in standardized laboratory tests is being used as a demonstration of consistency of the response of waste glasses in the final disposal environment. The leaching of silicate and borosilicate glasses containing alkali or alkaline earth elements is known to be autocatalytic, in that the initial ion exchange of alkali in the glass for hydrogen ions in water results in the formation of OH and increases the pH of the leachate. The increased pH then increases the rate of silicate network attack, accelerating the leaching effect. In well formulated glasses this effect reaches a thermodynamic equilibrium when leachate saturation of a critical species, such as silica, or a dynamic equilibrium is reached when the pH shift caused by incremental leaching has negligible effect on pH. This report analyzes results of a seven leach test on waste glasses

  4. Compartment-specific pH monitoring in Bacillus subtilis using fluorescent sensor proteins: a tool to analyze the antibacterial effect of weak organic acids.

    Science.gov (United States)

    van Beilen, Johan W A; Brul, Stanley

    2013-01-01

    The internal pH (pHi) of a living cell is one of its most important physiological parameters. To monitor the pH inside Bacillus subtilis during various stages of its life cycle, we constructed an improved version (IpHluorin) of the ratiometric, pH-sensitive fluorescent protein pHluorin by extending it at the 5' end with the first 24 bp of comGA. The new version, which showed an approximate 40% increase in fluorescence intensity, was expressed from developmental phase-specific, native promoters of B. subtilis that are specifically active during vegetative growth on glucose (PptsG) or during sporulation (PspoIIA, PspoIIID, and PsspE). Our results show strong, compartment-specific expression of IpHluorin that allowed accurate pHi measurements of live cultures during exponential growth, early and late sporulation, spore germination, and during subsequent spore outgrowth. Dormant spores were characterized by an pHi of 6.0 ± 0.3. Upon full germination the pHi rose dependent on the medium to 7.0-7.4. The presence of sorbic acid in the germination medium inhibited a rise in the intracellular pH of germinating spores and inhibited germination. Such effects were absent when acetic was added at identical concentrations.

  5. A microfabricated fringing field capacitive pH sensor with an integrated readout circuit

    International Nuclear Information System (INIS)

    Arefin, Md Shamsul; Redoute, Jean-Michel; Rasit Yuce, Mehmet; Bulut Coskun, M.; Alan, Tuncay; Neild, Adrian

    2014-01-01

    This work presents a microfabricated fringe-field capacitive pH sensor using interdigitated electrodes and an integrated modulation-based readout circuit. The changes in capacitance of the sensor result from the permittivity changes due to pH variations and are converted to frequency shifts using a crossed-coupled voltage controlled oscillator readout circuit. The shift in resonant frequency of the readout circuit is 30.96 MHz for a change in pH of 1.0–5.0. The sensor can be used for the measurement of low pH levels, such as gastric acid, and can be integrated with electronic pills. The measurement results show high repeatability, low noise, and a stable output.

  6. A microfabricated fringing field capacitive pH sensor with an integrated readout circuit

    Energy Technology Data Exchange (ETDEWEB)

    Arefin, Md Shamsul, E-mail: md.arefin@monash.edu; Redoute, Jean-Michel; Rasit Yuce, Mehmet [Electrical and Computer Systems Engineering, Monash University, Melbourne (Australia); Bulut Coskun, M.; Alan, Tuncay; Neild, Adrian [Mechanical and Aerospace Engineering, Monash University, Melbourne (Australia)

    2014-06-02

    This work presents a microfabricated fringe-field capacitive pH sensor using interdigitated electrodes and an integrated modulation-based readout circuit. The changes in capacitance of the sensor result from the permittivity changes due to pH variations and are converted to frequency shifts using a crossed-coupled voltage controlled oscillator readout circuit. The shift in resonant frequency of the readout circuit is 30.96 MHz for a change in pH of 1.0–5.0. The sensor can be used for the measurement of low pH levels, such as gastric acid, and can be integrated with electronic pills. The measurement results show high repeatability, low noise, and a stable output.

  7. Mutant p53 transfection of astrocytic cells results in altered cell cycle control, radiation sensitivity, and tumorigenicity

    International Nuclear Information System (INIS)

    Kanady, Kirk E.; Mei Su; Proulx, Gary; Malkin, David M.; Pardo, Francisco S.

    1995-01-01

    Introduction: Alterations in the p53 tumor suppressor gene are one of the most frequent genetic alterations in malignant gliomas. An understanding of the molecular genetic events leading to glial tumor progression would aid in designing therapeutic vectors for controlling these challenging tumor types. We investigated whether mutations in coding exons of the p53 gene result in functional changes altering cell cycle 'checkpoint' control and the intrinsic radiation sensitivity of glial cells. Methods: An astrocytic cell line was derived from a low grade astrocytoma and characterized to be of human karyotype and GFAP positivity. Additionally, the cellular population has never formed tumors in immune-deficient mice. At early passage ( 2 as parameters. Cell kinetic analyses after 2, 5, and 10 Gy of ionizing radiation were conducted using propidium iodide FACS analyses. Results: Overall levels of p53 expression were increased 5-10 fold in the transfected cellular populations. Astrocytic cellular populations transfected with mutant p53 revealed a statistically significant increase in levels of resistance to ionizing radiation in vitro (2-tailed test, SF2, MID). Astrocytic cellular populations transfected with mutant p53, unlike the parental cells, were tumorigenic in SCID mice. Cell kinetic analyses indicated that the untransfected cell line demonstrated dose dependent G1 and G2 arrests. Following transfection, however, the resultant cellular population demonstrated a predominant G2 arrest. Conclusions: Astrocytic cellular populations derived from low grade astrocytomas, are relatively radiation sensitive, non-tumorigenic, and have intact cell cycle ''checkpoints.'' Cellular populations resulting upon transfection of parental cells with a dominant negative p53 mutation, are relatively radiation resistant, when compared to both parental and mock-transfected cells. Transfected cells demonstrate abnormalities of cell cycle control at the G1/S checkpoint, increases in levels

  8. Exergoeconomic comparison of TLC (trilateral Rankine cycle), ORC (organic Rankine cycle) and Kalina cycle using a low grade heat source

    International Nuclear Information System (INIS)

    Yari, M.; Mehr, A.S.; Zare, V.; Mahmoudi, S.M.S.; Rosen, M.A.

    2015-01-01

    Recently, the TLC (trilateral power cycle) has attracted significant interest as it provides better matching between the temperature profiles in the evaporator compared to conventional power cycles. This article investigates the performance of this cycle and compares it with those for the ORC (organic Rankine cycle) and the Kalina cycle, from the viewpoints of thermodynamics and thermoeconomics. A low-grade heat source with a temperature of 120 °C is considered for all the three systems. Parametric studies are performed for the systems for several working fluids in the ORC and TLC. The systems are then optimized for either maximum net output power or minimum product cost, using the EES (engineering equation solver) software. The results for the TLC indicate that an increase in the expander inlet temperature leads to an increase in net output power and a decrease in product cost for this power plant, whereas this is not the case for the ORC system. It is found that, although the TLC can achieve a higher net output power compared with the ORC and Kalina (KCS11 (Kalina cycle system 11)) systems, its product cost is greatly affected by the expander isentropic efficiency. It is also revealed that using n-butane as the working fluid can result in the lowest product cost in the ORC and the TLC. In addition, it is observed that, for both the ORC and Kalina systems, the optimum operating condition for maximum net output power differs from that for minimum product cost. - Highlights: • Exergoeconomic analysis of trilateral Rankine cycle is performed. • The system performance is compared with Organic Rankine and Kalina cycles. • Net power from trilateral Rankine cycle is higher than the other power systems. • Superiority of trilateral cycle depends on its expander isentropic efficiency

  9. Evaluation of the 11CO2 positron emission tomographic method for measuring brain pH. I. pH changes measured in states of altered PCO2

    International Nuclear Information System (INIS)

    Buxton, R.B.; Alpert, N.M.; Babikian, V.; Weise, S.; Correia, J.A.; Ackerman, R.H.

    1987-01-01

    The 11 CO 2 method for measuring local brain pH with positron emission tomography (PET) has been experimentally evaluated, testing the adequacy of the kinetic model and the ability of the method to measure changes in brain pH. Plasma and tissue time/activity curves measured during and following continuous inhalation of 11 CO 2 were fit with a kinetic model that includes effects of tissue pH, blood flow, and fixation of CO 2 into compounds other than dissolved gas and bicarbonate ions. For each of ten dogs, brain pH was measured with PET at two values of PaCO 2 (range 21-67 mm Hg). The kinetic model fit the data well during both inhalation and washout of the label, with residual root mean square (RMS) deviations of the model from the measurements consistent with the statistical quality of the PET data. Brain pH calculated from the PET data shows a linear variation with log(PaCO 2 ). These results were in good agreement with previously reported measurements of brain pH, both in absolute value and in variation with PCO 2 . The interpretation of these pH values in normal and pathological states is discussed

  10. Microbial ecology of soda lakes: investigating sulfur and nitrogen cycling at Mono Lake, CA, USA

    Science.gov (United States)

    Fairbanks, D.; Phillips, A. A.; Wells, M.; Bao, R.; Fullerton, K. M.; Stamps, B. W.; Speth, D. R.; Johnson, H.; Sessions, A. L.

    2017-12-01

    Soda lakes represent unique ecosystems characterized by extremes of pH, salinity and distinct geochemical cycling. Despite these extreme conditions, soda lakes are important repositories of biological adaptation and have a highly functional microbial system. We investigated the biogeochemical cycling of sulfur and nitrogen compounds in Mono Lake, California, located east of the Sierra Nevada mountains. Mono lake is characterized by hyperalkaline, hypersaline and high sulfate concentrations and can enter prolonged periods of meromixis due to freshwater inflow. Typically, the microbial sulfur cycle is highly active in soda lakes with both oxidation and reduction of sulfur compounds. However, the biological sulfur cycle is connected to many other main elemental cycles such as carbon, nitrogen and metals. Here we investigated the interaction between sulfur and nitrogen cycling in Mono lake using a combination of molecular, isotopic, and geochemical observations to explore the links between microbial phylogenetic composition and functionality. Metagenomic and 16S rRNA gene amplicon sequencing were determined at two locations and five depths in May 2017. 16S rRNA gene amplicon sequencing analysis revealed organisms capable of both sulfur and nitrogen cycling. The relative abundance and distribution of functional genes (dsrA, soxAB, nifH, etc) were also determined. These genetic markers indicate the potential in situ relevance of specific carbon, nitrogen, and sulfur pathways in the water column prior to the transition to meromictic stratification. However, genes for sulfide oxidation, denitrification, and ammonification were present. Genome binning guided by the most abundant dsrA sequences, GC content, and abundance with depth identified a Thioalkalivibrio paradoxus bin containing genes capable of sulfur oxidation, denitrification, and nitrate reduction. The presence of a large number of sulfur and nitrogen cycling genes associated with Thioalkalivibrio paradoxus

  11. Analysis list: ph-d [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ph-d Cell line,Embryo + dm3 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/target/p...h-d.1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/target/ph-d.5.tsv http://dbarchive.biosciencedbc.jp.../kyushu-u/dm3/target/ph-d.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/colo/ph-d.Cell_line.tsv,http://dbarchive.bioscience...dbc.jp/kyushu-u/dm3/colo/ph-d.Embryo.tsv http://dbarchive.bioscience...dbc.jp/kyushu-u/dm3/colo/Cell_line.gml,http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/colo/Embryo.gml ...

  12. Life Cycle Sustainability Dashboard

    DEFF Research Database (Denmark)

    Traverso, Marzia; Finkbeiner, Matthias; Jørgensen, Andreas

    2012-01-01

    One method to assess the sustainability performance of products is life cycle sustainability assessment (LCSA), which assesses product performance considering the environmental,economic, and social dimensions of the life cycle. The results of LCSA can be used to compare different products...... of sustainability is the communicability of the results by means of a graphical representation (a cartogram), characterized by a suitable chromatic scale and ranking score. The integration of LCSA and the dashboard of sustainability into a so-called Life Cycle Sustainability Dashboard (LCSD) is described here...

  13. Manipulation of the Xanthophyll Cycle Increases Plant Susceptibility to Sclerotinia sclerotiorum.

    Directory of Open Access Journals (Sweden)

    Jun Zhou

    2015-05-01

    Full Text Available The xanthophyll cycle is involved in dissipating excess light energy to protect the photosynthetic apparatus in a process commonly assessed from non-photochemical quenching (NPQ of chlorophyll fluorescence. Here, it is shown that the xanthophyll cycle is modulated by the necrotrophic pathogen Sclerotinia sclerotiorum at the early stage of infection. Incubation of Sclerotinia led to a localized increase in NPQ even at low light intensity. Further studies showed that this abnormal change in NPQ was closely correlated with a decreased pH caused by Sclerotinia-secreted oxalate, which might decrease the ATP synthase activity and lead to a deepening of thylakoid lumen acidification under continuous illumination. Furthermore, suppression (with dithiothreitol or a defect (in the npq1-2 mutant of violaxanthin de-epoxidase (VDE abolished the Sclerotinia-induced NPQ increase. HPLC analysis showed that the Sclerotinia-inoculated tissue accumulated substantial quantities of zeaxanthin at the expense of violaxanthin, with a corresponding decrease in neoxanthin content. Immunoassays revealed that the decrease in these xanthophyll precursors reduced de novo abscisic acid (ABA biosynthesis and apparently weakened tissue defense responses, including ROS induction and callose deposition, resulting in enhanced plant susceptibility to Sclerotinia. We thus propose that Sclerotinia antagonizes ABA biosynthesis to suppress host defense by manipulating the xanthophyll cycle in early pathogenesis. These findings provide a model of how photoprotective metabolites integrate into the defense responses, and expand the current knowledge of early plant-Sclerotinia interactions at infection sites.

  14. Preparing MD-PhD students for clinical rotations: navigating the interface between PhD and MD training.

    Science.gov (United States)

    Goldberg, Charles; Insel, Paul A

    2013-06-01

    Many aspects of MD-PhD training are not optimally designed to prepare students for their future roles as translational clinician-scientists. The transition between PhD research efforts and clinical rotations is one hurdle that must be overcome. MD-PhD students have deficits in clinical skills compared with those of their MD-only colleagues at the time of this transition. Reimmersion programs (RPs) targeted to MD-PhD students have the potential to help them navigate this transition.The authors draw on their experience creating and implementing an RP that incorporates multiple types of activities (clinical exam review, objective structured clinical examination, and supervised practice in patient care settings) designed to enhance the participants' skills and readiness for clinical efforts. On the basis of this experience, they note that MD-PhD students' time away from the clinical environment negatively affects their clinical skills, causing them to feel underprepared for clinical rotations. The authors argue that participation in an RP can help students feel more comfortable speaking with and examining patients and decrease their anxiety regarding clinical encounters. The authors propose that RPs can have positive outcomes for improving the transition from PhD to clinical MD training in dual-degree programs. Identifying and addressing this and other transitions need to be considered to improve the educational experience of MD-PhD students.

  15. Impact of biogeochemical processes on pH dynamics in marine systems

    NARCIS (Netherlands)

    Hagens, Mathilde

    2015-01-01

    Uptake of anthropogenic carbon dioxide (CO2) from the atmosphere has resulted in a range of changes in ocean chemistry, including the lowering of pH, collectively referred to as ocean acidification. Rates of coastal-zone acidification exceed those of the open ocean since coastal-ocean pH is

  16. Ammonia-water Rankine cycle

    International Nuclear Information System (INIS)

    Bo Hanliang; Ma Changwen; Wu Shaorong

    1997-01-01

    On characteristics of heating source and cooling source in nuclear heating reactor cooperation, the authors advance a new kind of power cycle in which a multicomponent mixture as the work fluid, ammonia-water Rankine cycle, describe its running principle, and compare it with steam Rankine cycle in the same situation. The result is that: the new kind of power cycle, ammonia-water Rankine cycle has higher electricity efficiency; it suits for the situation of heating source and cooling source which offered by nuclear heating reactor cooperation. For low temperature heating source, it maybe has a widely application

  17. Determination of pH by flow-injection analysis and by fiber-optrode analysis

    International Nuclear Information System (INIS)

    Pia, S.H.; Waltman, D.P.; Hillman, D.C.

    1988-07-01

    Two new procedures for measuring pH were developed. The first measures pH colorimetrically using a proprietary indicator-dye mixture in a flow injection analysis (FIA) procedure. The second measures pH using a fiber-optic chemical sensor (FOCS) specifically developed for pH determinations. The FOCS method measures pH by monitoring the fluorescence of a fluorescein derivative bonded to the distal end of a fiber-optic cable called an optrade. The FIA method currently has a precision and accuracy of about + or - 0.2 pH units and can measure 100 samples/hour. The FOCS method has a precision of + or - 0.05-0.20 pH units and an accuracy of + or - 0.1 to 0.6 pH units. About 10 to 60 samples can be analyzed. The characteristics of the FOCS Method will vary significantly with individual optrodes. The experimental results indicate that either flow-injection analysis or fiber optic chemical sensor analysis could form the basis for an alternative to electrometric measurement of pH in certain circumstances

  18. Miniaturized pH Sensors Based on Zinc Oxide Nanotubes/Nanorods

    Directory of Open Access Journals (Sweden)

    Magnus Willander

    2009-11-01

    Full Text Available ZnO nanotubes and nanorods grown on gold thin film were used to create pH sensor devices. The developed ZnO nanotube and nanorod pH sensors display good reproducibility, repeatability and long-term stability and exhibit a pH-dependent electrochemical potential difference versus an Ag/AgCl reference electrode over a large dynamic pH range. We found the ZnO nanotubes provide sensitivity as high as twice that of the ZnO nanorods, which can be ascribed to the fact that small dimensional ZnO nanotubes have a higher level of surface and subsurface oxygen vacancies and provide a larger effective surface area with higher surface-to-volume ratio as compared to ZnO nanorods, thus affording the ZnO nanotube pH sensor a higher sensitivity. Experimental results indicate ZnO nanotubes can be used in pH sensor applications with improved performance. Moreover, the ZnO nanotube arrays may find potential application as a novel material for measurements of intracellular biochemical species within single living cells.

  19. Infectious pancreatic necrosis virus in fish by-products is inactivated with inorganic acid (pH 1) and base (pH 12).

    Science.gov (United States)

    Myrmel, M; Modahl, I; Nygaard, H; Lie, K M

    2014-04-01

    The aquaculture industry needs a simple, inexpensive and safe method for the treatment of fish waste without heat. Microbial inactivation by inorganic acid (HCl) or base (KOH) was determined using infectious pancreatic necrosis virus (IPNV) as a model organism for fish pathogens. Salmonella and spores of Clostridium perfringens were general hygiene indicators in supplementary examinations. IPNV, which is considered to be among the most chemical- and heat-resistant fish pathogens, was reduced by more than 3 log in 4 h at pH 1.0 and pH 12.0. Salmonella was rapidly inactivated by the same treatment, whereas spores of C. perfringens were hardly affected. The results indicate that low and high pH treatment could be particularly suitable for fish waste destined for biogas production. pH treatment at aquaculture production sites could reduce the spread of fish pathogens during storage and transportation without disturbing the anaerobic digestion process. The treatment could also be an alternative to the current energy-intensive steam pressure sterilization of fish waste to be used by the bioenergy, fertilizer and soil improver industries. © 2013 John Wiley & Sons Ltd.

  20. Plant Habitat (PH)

    Science.gov (United States)

    Onate, Bryan

    2016-01-01

    The International Space Station (ISS) will soon have a platform for conducting fundamental research of Large Plants. Plant Habitat (PH) is designed to be a fully controllable environment for high-quality plant physiological research. PH will control light quality, level, and timing, temperature, CO2, relative humidity, and irrigation, while scrubbing ethylene. Additional capabilities include leaf temperature and root zone moisture and oxygen sensing. The light cap will have red (630 nm), blue (450 nm), green (525 nm), far red (730 nm) and broad spectrum white LEDs. There will be several internal cameras (visible and IR) to monitor and record plant growth and operations.

  1. Programmable pH buffers

    Science.gov (United States)

    Gough, Dara Van; Huber, Dale L.; Bunker, Bruce C.; Roberts, Mark E.

    2017-01-24

    A programmable pH buffer comprises a copolymer that changes pK.sub.a at a lower critical solution temperature (LCST) in water. The copolymer comprises a thermally programmable polymer that undergoes a hydrophobic-to-hydrophilic phase change at the LCST and an electrolytic polymer that exhibits acid-base properties that are responsive to the phase change. The programmable pH buffer can be used to sequester CO.sub.2 into water.

  2. The PhD Conundrum in South African Academia

    Science.gov (United States)

    Breier, Mignonne; Herman, Chaya

    2017-01-01

    South African universities need more academics with PhDs, from historically disadvantaged population groups in particular, but they face a conundrum. In order to have more staff with PhDs, they need to produce more PhD graduates. But in order to produce more PhD graduates, they need more staff with PhDs to supervise. This article explores this…

  3. Synthesis and characterization of pH sensitive carboxySNARF-1 nanoreactors

    International Nuclear Information System (INIS)

    Chen Yenchi; Ostafin, Agnes; Mizukami, Hiroshi

    2010-01-01

    A rapid response dual wavelength emission pH sensor consisting of carboxySNARF-1 nanoreactors has been synthesized and shown to provide accurate pH measurements even in complex biological media, where the unprotected pH responsive dyes have failed. The carboxySNARF-1 nanoreactor is made of a calcium phosphate shell covering phosphatidylcholine liposomes filled with the dye. Its mean diameter is 150 nm with dynamic light scattering, the shell thickness is 5-7 nm with TEM, and it contains about 10 dyes/particle. The nanoreactor's response time to pH change nearly equals that of the dye in solution. Its pH titration curves at two different wavelengths are equivalent to those of the dye in solution and fluorescence intensity ratio dependent pH analysis is possible using the modified Henderson-Hasselbalch equation. However, the pH dependent fluorescence ratios of the dye in solution in the presence of plasma and albumin are distorted, and application of the Henderson-Hasselbalch equation is not possible. We have found that the distortions may be restored using cSNARF-1 nanoreactors and the pK a of the dye in the nanoreactor then equals that in solution. These results suggest that the interference to the dye for the pH analyses with the environmental molecules may be reduced or prohibited by usage of cSNARF-1 nanoreactors.

  4. Synthesis and characterization of pH sensitive carboxySNARF-1 nanoreactors

    Energy Technology Data Exchange (ETDEWEB)

    Chen Yenchi; Ostafin, Agnes [Department of Materials Science, University of Utah, Salt Lake City, UT (United States); Mizukami, Hiroshi, E-mail: a.ostafin@utah.edu [Department of Biological Science, Wayne State University, Detroit, MI (United States)

    2010-05-28

    A rapid response dual wavelength emission pH sensor consisting of carboxySNARF-1 nanoreactors has been synthesized and shown to provide accurate pH measurements even in complex biological media, where the unprotected pH responsive dyes have failed. The carboxySNARF-1 nanoreactor is made of a calcium phosphate shell covering phosphatidylcholine liposomes filled with the dye. Its mean diameter is 150 nm with dynamic light scattering, the shell thickness is 5-7 nm with TEM, and it contains about 10 dyes/particle. The nanoreactor's response time to pH change nearly equals that of the dye in solution. Its pH titration curves at two different wavelengths are equivalent to those of the dye in solution and fluorescence intensity ratio dependent pH analysis is possible using the modified Henderson-Hasselbalch equation. However, the pH dependent fluorescence ratios of the dye in solution in the presence of plasma and albumin are distorted, and application of the Henderson-Hasselbalch equation is not possible. We have found that the distortions may be restored using cSNARF-1 nanoreactors and the pK{sub a} of the dye in the nanoreactor then equals that in solution. These results suggest that the interference to the dye for the pH analyses with the environmental molecules may be reduced or prohibited by usage of cSNARF-1 nanoreactors.

  5. Salivary pH as a marker of plasma adiponectin concentrations in Women

    Directory of Open Access Journals (Sweden)

    Tremblay Monique

    2012-02-01

    Full Text Available Abstract Background Plasma adiponectin is a significant correlate of the pro-inflammatory cardiometabolic risk profile associated with obesity and type 2 diabetes. Salivary pH is influenced by several cardiometabolic risk components such as inflammation, oxidation and numerous oral and systemic health modulators, including the menopausal status. This study aimed to assess the association between plasma adiponectin concentrations and salivary pH in women according to the menopausal status. Method Unstimulated saliva collection was performed in 151 Caucasian women of French-Canadian origin (53 premenopausal women (PMW and 98 menopausal women (MW. Student's t test, ANOVA and linear regression models were used to assess the association between plasma adiponectin concentrations and salivary pH. Results Plasma adiponectin levels increased as a function of salivary pH in the whole sample and among MW (r = 0.29 and r = 0.36, p 2 was 10.8% (p Conclusions These results suggest that salivary pH is a significant correlate of plasma adiponectin levels in women. With the increasing prevalence of type 2 diabetes and obesity, new technologies should be developed to more easily monitor health status, disease onset and progression. Salivary pH, a simple, inexpensive and non-invasive measure, could be a very promising avenue.

  6. Novel combined cycle configurations for propane pre-cooled mixed refrigerant (APCI) natural gas liquefaction cycle

    International Nuclear Information System (INIS)

    Mortazavi, Amir; Alabdulkarem, Abdullah; Hwang, Yunho; Radermacher, Reinhard

    2014-01-01

    Highlights: • 10 New LNG plants driver cycle enhancement configurations were developed. • All the 14 enhancement options design variables were optimized to demonstrate their energy saving potentials. • The best driver cycle enhancement option improved the driver cycle energy efficiency by 38%. • The effects of technological advancements on the performances of the enhancement options were studied. - Abstract: A significant amount of energy is required for natural gas liquefaction. Due to the production scale of LNG plants, they consume an intensive amount of energy. Consequently, any enhancement to the energy efficiency of LNG plants will result in a considerable reduction in natural gas consumption and CO 2 emission. Compressor drivers are the main energy consumer in the LNG plants. In this paper, 14 different driver cycle enhancement options were considered. A number of these options have not been proposed for the LNG plants. The new driver cycle development was performed by analyzing and optimizing the design variables of four conventional driver cycle enhancement options. The optimization results were used to develop more efficient cycles through mitigating the active constrains and driver cycle innovations. Based on the current available technologies five of our newly developed driver cycle configurations have higher efficiency than the most efficient existing conventional driver cycle. The best developed driver cycle enhancement option improved the base driver cycle energy efficiency by 38%. The effects of technological advancement on the performances of the all driver cycle enhancement options were also considered

  7. Microscopic monitoring of extracellular pH in dental biofilms

    DEFF Research Database (Denmark)

    Schlafer, Sebastian; Garcia, Javier; Greve, Matilde

    pH in dental biofilm is a key virulence factor for the development of caries lesions. The complex three-dimensional architecture of dental biofilms leads to steep gradients of nutrients and metabolites, including organic acids, across the biofilm. For decades, measuring pH in dental biofilm has...... been limited to monitoring bulk pH with electrodes. Although pH microelectrodes with a better spatial resolution have been developed, they do not permit to monitor horizontal pH gradients in real-time. Quantitative fluorescent microscopic techniques, such as fluorescence lifetime imaging or pH...... ratiometry, can be employed to map the pH landscape in dental biofilm with more detail. However, when pH sensitive fluorescent probes are used to visualize pH in biofilms, it is crucial to differentiate between extracellular and intracellular pH. Intracellular microbial pH and pH in the extracellular matrix...

  8. A protein-dye hybrid system as a narrow range tunable intracellular pH sensor.

    Science.gov (United States)

    Anees, Palapuravan; Sudheesh, Karivachery V; Jayamurthy, Purushothaman; Chandrika, Arunkumar R; Omkumar, Ramakrishnapillai V; Ajayaghosh, Ayyappanpillai

    2016-11-18

    Accurate monitoring of pH variations inside cells is important for the early diagnosis of diseases such as cancer. Even though a variety of different pH sensors are available, construction of a custom-made sensor array for measuring minute variations in a narrow biological pH window, using easily available constituents, is a challenge. Here we report two-component hybrid sensors derived from a protein and organic dye nanoparticles whose sensitivity range can be tuned by choosing different ratios of the components, to monitor the minute pH variations in a given system. The dye interacts noncovalently with the protein at lower pH and covalently at higher pH, triggering two distinguishable fluorescent signals at 700 and 480 nm, respectively. The pH sensitivity region of the probe can be tuned for every unit of the pH window resulting in custom-made pH sensors. These narrow range tunable pH sensors have been used to monitor pH variations in HeLa cells using the fluorescence imaging technique.

  9. IMPACT OF WATER PH ON ZEBRA MUSSEL MORTALITY

    International Nuclear Information System (INIS)

    Molloy, Daniel P.

    2002-01-01

    The experiments conducted this past quarter have suggested that the bacterium Pseudomonas fluorescens strain CL0145A is effective at killing zebra mussels throughout the entire range of pH values tested (7.2 to 8.6). Highest mortality was achieved at pH values characteristic of preferred zebra mussel waterbodies, i.e., hard waters with a range of 7.8 to 8.6. In all water types tested, however, ranging from very soft to very hard, considerable mussel kill was achieved (83 to 99% mean mortality), suggesting that regardless of the pH or hardness of the treated water, significant mussel kill can be achieved upon treatment with P. fluorescens strain CL0145A. These results further support the concept that this bacterium has significant potential for use as a zebra mussel control agent in power plant pipes receiving waters with a wide range of physical and chemical characteristics

  10. IMPACT OF WATER PH ON ZEBRA MUSSEL MORTALITY

    Energy Technology Data Exchange (ETDEWEB)

    Daniel P. Molloy

    2002-10-15

    The experiments conducted this past quarter have suggested that the bacterium Pseudomonas fluorescens strain CL0145A is effective at killing zebra mussels throughout the entire range of pH values tested (7.2 to 8.6). Highest mortality was achieved at pH values characteristic of preferred zebra mussel waterbodies, i.e., hard waters with a range of 7.8 to 8.6. In all water types tested, however, ranging from very soft to very hard, considerable mussel kill was achieved (83 to 99% mean mortality), suggesting that regardless of the pH or hardness of the treated water, significant mussel kill can be achieved upon treatment with P. fluorescens strain CL0145A. These results further support the concept that this bacterium has significant potential for use as a zebra mussel control agent in power plant pipes receiving waters with a wide range of physical and chemical characteristics.

  11. Changes of Soil Aggregate Stability as a Result of the Effect of Freeze-thaw Cycles

    Directory of Open Access Journals (Sweden)

    Aneta Žabenská

    2015-01-01

    Full Text Available The objective of the present research was to assess the changes in soil erodibility during the non-vegetation period as one of the factors affecting the snowmelt erosion. The temperature fluctuation was simulated with the use of a climatic chamber ex situ. The soil surface was for simplicity reasons considered without any plant or snow cover. The paper deals with the rate of soil erodibility determination – the soil erodibility should increase due to the decrease of soil aggregate stability depending on the number of freeze-thaw cycles and initial soil moisture. Soil samples (taken from three sites were subjected to freeze-thaw cycles under laboratory conditions. Changes in soil agreggate stability were monitored as one of the main soil characteristics which determine the soil erodibility. Two methods were used to determine the soil macroaggregate stability (soil aggregate fraction 1–2 mm: standard single-sieve method of wet sieving (Kemper and Rosenau, 1986, and dry aggregate analysis using a set of flat sieves with a diameter of 1 mm and 0.5 mm. The results of each method are controversial. Intended hypothesis has not been clearly confirmed.

  12. [Diagnosis of human brucellosis. Role of pH in the seroagglutination test and influence of pH on the agglutinating activity of IgM, IgG and IgA antibodies].

    Science.gov (United States)

    Rubio Vallejo, Manuel; del Pozo, José L; Del Pozo León, José Luis; Hernández-Molina, Juan Manuel; Dorronsoro Ibero, Inés; Marrodán Ciordia, Teresa; Díaz García, Ramón

    2002-04-01

    To evaluate the role of pH in the seroagglutination test (SAT)and Rose Bengal (RB) test, and to determine the influence of pH on the agglutinating activity of IgM, IgG and IgA antibodies. The SAT was performed at pH 7.2 or pH 5.0 in standard microtiter-type polystyrene plates using Ring Test antigen or the Brucella suspension (BRUCAPT) provided in the Brucellacapt kits. Specific antibodies against native hapten were determined by radial immunodiffusion. Additionally, IgG, IgA and IgM fractions were separated from 8 sera by absorption chromatography and their agglutinating capacity was studied at pH 7.2 and 5.0. We studied 72 sera from patients with clinical brucellosis taken at the time of hospitalization, 16 from persons in contact with infected animals, and 16 from healthy donors. SAT results at pH 5.0 correlated with those obtained with the Rose Bengal test. Four Rose Bengal-positive sera were found to be SAT-negative at pH 7.2 and SAT-positive at pH 5.0. SAT performed at pH 5.0 with BRUCAPT antigen yielded higher titers than tests performed at pH 7.2 or 5.0 with Ring Test antigen (p IgA fractions were SAT-negative at pH 7.2 and SAT-positive at pH 5.0; the other 5 agglutinated at both pH conditions and were DTT-sensitive. All IgA fractions but one were positive by Rose Bengal. Agglutinating activity of the IgM fraction was not affected by pH. The SAT performed with the buffer and antigen suspension included in the Brucellacapt kit (pH 5.0) is highly useful for detecting agglutinating and non-agglutinating antibodies at pH 7.2.

  13. Studies on luteinizing hormone receptors of human corpora lutea during menstrual cycle and pregnancy

    Energy Technology Data Exchange (ETDEWEB)

    Izumi, Yasushi (Keio Univ., Tokyo (Japan). School of Medicine)

    1982-10-01

    With the purpose of explicating the lifespan of human corpora lutea, using human corpora lutea of the menstrual cycle and pregnancy, binding of /sup 125/I-LH to the 20,000g cell membrane fraction was examined. 1) Specific bindings of /sup 125/I-LH, /sup 125/I-HCG were demonstrated in the 20,000g cell membrane fraction. Although LH and HCG were parallel in inhibiting /sup 125/I-LH binding, HCG was found to be more effective. FSH did not inhibit binding. 2) Binding of /sup 125/I-LH was dependent on time, temperature, /sup 125/I-LH concentration, amount of the cell membrane fraction protein and pH. The highest binding was seen at pH 6.0 while incubating for 60 min at 37/sup 0/C. 3) The number of LH receptors in human corpora lutea of the menstrual cycle increased towards midluteal phase, especially on 5th day from ovulation, and decreased towards late luteal phase. LH receptor was not found in corpus albicans. The apparent dissociation constant of each corpus luteum did not change throughout the menstrual cycle. 4) Corpora lutea of pregnancy contained a few or no receptors which bound /sup 125/I-LH specifically. These data suggest that LH receptor is an important factor regulating the lifespan of corpus luteum and exogenous HCG has effect on luteal insufficiency, but the effect of HCG on threatened abortion is uncertain.

  14. Determination Of Ph Including Hemoglobin Correction

    Science.gov (United States)

    Maynard, John D.; Hendee, Shonn P.; Rohrscheib, Mark R.; Nunez, David; Alam, M. Kathleen; Franke, James E.; Kemeny, Gabor J.

    2005-09-13

    Methods and apparatuses of determining the pH of a sample. A method can comprise determining an infrared spectrum of the sample, and determining the hemoglobin concentration of the sample. The hemoglobin concentration and the infrared spectrum can then be used to determine the pH of the sample. In some embodiments, the hemoglobin concentration can be used to select an model relating infrared spectra to pH that is applicable at the determined hemoglobin concentration. In other embodiments, a model relating hemoglobin concentration and infrared spectra to pH can be used. An apparatus according to the present invention can comprise an illumination system, adapted to supply radiation to a sample; a collection system, adapted to collect radiation expressed from the sample responsive to the incident radiation; and an analysis system, adapted to relate information about the incident radiation, the expressed radiation, and the hemoglobin concentration of the sample to pH.

  15. Early Evolution of Earth's Geochemical Cycle and Biosphere: Implications for Mars Exobiology

    Science.gov (United States)

    DesMarais, David J.; Chang, Sherwood (Technical Monitor)

    1997-01-01

    Carbon (C) has played multiple key roles for life and its environment. C has formed organics, greenhouse gases, aquatic pH buffers, redox buffers, and magmatic constituents affecting plutonism and volcanism. These roles interacted across a network of reservoirs and processes known as the biogeochemical C cycle. Changes in the cycle over geologic time were driven by increasing solar luminosity, declining planetary heat flow, and continental and biological evolution. The early Archean C cycle was dominated by hydrothermal alteration of crustal rocks and by thermal emanations of CO2 and reduced species (eg., H2, Fe(2+) and sulfides). Bioorganic synthesis was achieved by nonphotosynthetic CO2-fixing bacteria (chemoautotrophs) and, possibly, bacteria (organotrophs) utilizing any available nonbiological organic C. Responding both to abundant solar energy and to a longterm decline in thermal sources of chemical energy and reducing power, the blaspheme first developed anoxygenic photosynthesis, then, ultimately, oxygenic photosynthesis. O2-photosynthesis played a central role in transforming the ancient environment and blaspheme to the modem world. The geochemical C cycles of early Earth and Mars were quite similar. The principal differences between the modem C cycles of these planets arose during the later evolution of their heat flows, crusts, atmospheres and, perhaps, their blasphemes.

  16. Characterizing cycle-to-cycle variations of the shedding cycle in the turbulent wake of a normal flat plate using generalized phase averages

    Science.gov (United States)

    Martinuzzi, Robert

    2016-11-01

    Quasi-periodic vortex shedding in the turbulent wake of a thin-flat plate placed normal to a uniform stream at Reynolds number of 6700 is investigated based on Particle Image Velocimetry experiments. The wake structure and vortex formation are characterized using a generalized phase average (GPA), a refinement of the triple decomposition of Reynolds and Hussain (1970) incorporating elements of mean-field theory (Stuart, 1958). The resulting analysis highlights the importance of cycle-to-cycle variations in characterizing vortex formation, wake topology and the residual turbulent Reynolds Stresses. For example, it is shown that during high-amplitude cycles vorticity is strongly concentrated within the well-organized shed vortices, whereas during low-amplitude cycles the shed vortices are highly distorted resulting in significant modulation of the shedding frequency. It is found that high-amplitude cycles contribute more to the coherent Reynolds stress field while the low-amplitude cycles contribute to the residual stress field. It is further shown that traditional phase-averaging techniques lead to an over-estimation of the residual stress field. Natural Sciences and Engineering Research Council of Canada.

  17. Menstrual cycle pattern and fertility

    DEFF Research Database (Denmark)

    Kolstad, Henrik A.; Bonde, Jens Peter; Hjøllund, Niels Henrik

    1999-01-01

    OBJECTIVE: To characterize how the menstrual cycle pattern relates to fertility regardless of potential biases caused by inappropriate coital timing during the menstrual cycle or early embryonal loss. DESIGN: Prospective follow-up study. SETTING: Healthy couples recruited throughout Denmark....... PATIENT(S): Two hundred ninety-five couples who were planning their first pregnancy were followed up from the discontinuation of birth control until a pregnancy was recognized within six menstrual cycles. Early embryonal losses were detected by changes in urinary hCG levels. INTERVENTION(S): None. MAIN...... OUTCOME MEASURE(S): The probability of pregnancy occurring within one menstrual cycle (fecundity). RESULT(S): In women who had a cycle length that differed by >10 days from the usual cycle length, fecundity was approximately 25% that of women who had no variation (odds ratio 0.25, 95% confidence interval...

  18. The mechanism of electron gating in proton pumping cytochrome c oxidase: the effect of pH and temperature on internal electron transfer.

    Science.gov (United States)

    Brzezinski, P; Malmström, B G

    1987-10-29

    Electron-transfer reactions following flash photolysis of the mixed-valence cytochrome oxidase-CO complex have been measured at 445, 598 and 830 nm between pH 5.2 and 9.0 in the temperature range of 0-25 degrees C. There is a rapid electron transfer from the cytochrome a3-CuB pair to CuA (time constant: 14200 s-1), which is followed by a slower electron transfer to cytochrome a. Both the rate and the amplitude of the rapid phase are independent of pH, and the rate in the direction from CuA to cytochrome a3-CuB is practically independent of temperature. The second phase depends strongly on pH due to the titration of an acid-base group with pKa = 7.6. The equilibrium at pH 7.4 corresponds to reduction potentials of 225 and 345 mV for cytochrome a and a3, respectively, from which it is concluded that the enzyme is in a different conformation compared to the fully oxidized form. The results have been used to suggest a series of reaction steps in a cycle of the oxidase as a proton pump. Application of the electron-transfer theory to the temperature-dependence data suggests a mechanism for electron gating in the pump. Reduction of both cytochrome a and CuA leads to a conformational change, which changes the structure of cytochrome a3-CuB in such a way that the reorganizational barrier for electron transfer is removed and the driving force is increased.

  19. The influence of calcium and pH on growth in primary roots of Zea mays

    Science.gov (United States)

    Hasenstein, K. H.; Evans, M. L.

    1988-01-01

    We investigated the interaction of Ca2+ and pH on root elongation in Zea mays L. cv. B73 x Missouri 17 and cv. Merit. Seedlings were raised to contain high levels of Ca2+ (HC, imbibed and raised in 10 mM CaCl2) or low levels of Ca2+ (LC, imbibed and raised in distilled water). In HC roots, lowering the pH (5 mM MES/Tris) from 6.5 to 4.5 resulted in strong, long-lasting growth promotion. Surprisingly, increasing the pH from 6.5 to 8.5 also resulted in strong growth promotion. In LC roots acidification of the medium (pH 6.5 to 4.5) resulted in transient growth stimulation followed by a gradual decline in the growth rate toward zero. Exposure of LC roots to high pH (pH shift from 6.5 to 8.5) also promoted growth. Addition of EGTA resulted in strong growth promotion in both LC and HC roots. The ability of EGTA to stimulate growth appeared not to be related to H+ release from EGTA upon Ca2+ chelation since, 1) LC roots showed a strong and prolonged response to EGTA, but only a transient response to acid pH, and 2) promotion of growth by EGTA was observed in strongly buffered solutions. We also examined the pH dependence of the release of 45Ca2+ from roots of 3-day-old seedlings grown from grains imbibed in 45Ca2+. Release of 45Ca2+ from the root into agar blocks placed on the root surface was greater the more acidic the pH of the blocks. The results indicate that Ca2+ may be necessary for the acid growth response in roots.

  20. Improvement of the respiration efficiency of Lactococcus lactis by decreasing the culture pH.

    Science.gov (United States)

    Shi, Weijia; Li, Yu; Gao, Xueling; Fu, Ruiyan

    2016-03-01

    The growth characteristics and intracellular hemin concentrations of Lactococcus lactis grown under different culture pH and aeration conditions were examined to investigate the effect of culture pH on the respiration efficiency of L. lactis NZ9000 (pZN8148). Cell biomass and biomass yield of L. lactis grown with 4 μg hemin/ml and O2 were higher than those without aeration when the culture pH was controlled at 5-6.5. The culture pH affected the respiratory efficiency in the following order of pH: 5 > 5.5 > 6 > 6.5; the lag phase increased as the culture pH decreased. Hemin accumulation was sensitive to culture pH. Among the four pH conditions, pH 5.5 was optimal for hemin accumulation in the cells. The highest intracellular hemin level in L. lactis resting cells incubated at different pH saline levels (5-6.5) was at pH 5.5. The respiration efficiency of L. lactis under respiration-permissive conditions increases markedly as the culture pH decreases. These results may help develop high cell-density L. lactis cultures. Thus, this microorganism may be used for industrial applications.

  1. Ambulatory oesophageal pH monitoring: a comparison between antimony, ISFET, and glass pH electrodes

    NARCIS (Netherlands)

    Hemmink, Gerrit J. M.; Weusten, Bas L. A. M.; Oors, Jac; Bredenoord, Albert J.; Timmer, Robin; Smout, André J. P. M.

    2010-01-01

    BACKGROUND AND AIM: Ambulatory oesophageal pH-impedance monitoring is a widely used test to evaluate patients with reflux symptoms. Several types of pH electrodes are available: antimony, ion sensitive field effect transistor (ISFET), and glass electrodes. These pH electrodes have not been compared

  2. Diurnal cycles control the fate of contaminants at an Andean river confluence impacted by legacy mining

    Science.gov (United States)

    Pasten, P.; Guerra, P. A.; Simonson, K.; Bonilla, C.; Pizarro, G. E.; Escauriaza, C. R.; González, C.

    2014-12-01

    The importance of hydrologic-geochemical interactions in arid environments is a controlling factor in quality and quantity of water available for human consumption and agriculture. When acid drainage affects these watersheds, water quality is gravely degraded. Despite its effect on watersheds, the relationship between time changes in hydrological variables and water quality in arid regions has not been studied thoroughly. Temporal variations in acid drainage can control when the transport of toxic elements is increased. We performed field work at the Azufre River (pH 2, E.C~10.9 mS/cm) and Caracarani River (pH 8.7, E.C~1.2 mS/cm) confluence, located in the Northern Chilean Altiplano (at 4000 m asl). We registered stream flowrates (total flowrate~430 L/s), temperature and electric conductivity (E.C) hourly using in-stream data loggers during one year. We also measured turbidity and pH during one field survey at different distances from the junction, as a proxy of the formation of iron-aluminum particles that cycle trace elements in these environments. We found turbidity-pH diurnal cycles were caused by upstream hourly changes in upstream flowrate: when the Caracarani River flowrate reached its daily peak, particle formation occurred, while the dissolution of particles occurred when the Azufre River reached its maximum value. This last process occurred due to upstream freeze-thaw cycles. This study shows how the dynamics of natural confluences determines chemical transport. The formation of particles enriched in toxic elements can promote settling as a natural attenuation process, while their dissolution will produce their release and transport long distances downstream. It is important to consider time as an important variable in water quality monitoring and in water management infrastructure where pulses of contamination can have potentially negative effects in its use. Acknowledgements: Funding was provided by "Proyecto Fondecyt 1130936" and "CONICYT

  3. Acidic Food pH Increases Palatability and Consumption and Extends Drosophila Lifespan.

    Science.gov (United States)

    Deshpande, Sonali A; Yamada, Ryuichi; Mak, Christine M; Hunter, Brooke; Soto Obando, Alina; Hoxha, Sany; Ja, William W

    2015-12-01

    Despite the prevalent use of Drosophila as a model in studies of nutrition, the effects of fundamental food properties, such as pH, on animal health and behavior are not well known. We examined the effect of food pH on adult Drosophila lifespan, feeding behavior, and microbiota composition and tested the hypothesis that pH-mediated changes in palatability and total consumption are required for modulating longevity. We measured the effect of buffered food (pH 5, 7, or 9) on male gustatory responses (proboscis extension), total food intake, and male and female lifespan. The effect of food pH on germfree male lifespan was also assessed. Changes in fly-associated microbial composition as a result of food pH were determined by 16S ribosomal RNA gene sequencing. Male gustatory responses, total consumption, and male and female longevity were additionally measured in the taste-defective Pox neuro (Poxn) mutant and its transgenic rescue control. An acidic diet increased Drosophila gustatory responses (40-230%) and food intake (5-50%) and extended survival (10-160% longer median lifespan) compared with flies on either neutral or alkaline pH food. Alkaline food pH shifted the composition of fly-associated bacteria and resulted in greater lifespan extension (260% longer median survival) after microbes were eliminated compared with flies on an acidic (50%) or neutral (130%) diet. However, germfree flies lived longer on an acidic diet (5-20% longer median lifespan) compared with those on either neutral or alkaline pH food. Gustatory responses, total consumption, and longevity were unaffected by food pH in Poxn mutant flies. Food pH can directly influence palatability and feeding behavior and affect parameters such as microbial growth to ultimately affect Drosophila lifespan. Fundamental food properties altered by dietary or drug interventions may therefore contribute to changes in animal physiology, metabolism, and survival. © 2015 American Society for Nutrition.

  4. Articulating Expectations for PhD Candidature upon Commencement: Ensuring Supervisor/Student "Best Fit"

    Science.gov (United States)

    Moxham, Lorna; Dwyer, Trudy; Reid-Searl, Kerry

    2013-01-01

    The journey towards completion of a PhD is a bumpy one for many. One of the major factors that influence successful and on-time thesis completion is the relationship that the PhD candidate has with her or his supervisor. This paper presents results from research undertaken using a 12-item survey to collect data from a purposive sample: PhD…

  5. Histone deacetylase-mediated regulation of endolysosomal pH.

    Science.gov (United States)

    Prasad, Hari; Rao, Rajini

    2018-05-04

    The pH of the endolysosomal system is tightly regulated by a balance of proton pump and leak mechanisms that are critical for storage, recycling, turnover, and signaling functions in the cell. Dysregulation of endolysosomal pH has been linked to aging, amyloidogenesis, synaptic dysfunction, and various neurodegenerative disorders, including Alzheimer's disease. Therefore, understanding the mechanisms that regulate luminal pH may be key to identifying new targets for managing these disorders. Meta-analysis of yeast microarray databases revealed that nutrient-limiting conditions inhibited the histone deacetylase (HDAC) Rpd3 and thereby up-regulated transcription of the endosomal Na + /H + exchanger Nhx1, resulting in vacuolar alkalinization. Consistent with these findings, Rpd3 inhibition by the HDAC inhibitor and antifungal drug trichostatin A induced Nhx1 expression and vacuolar alkalinization. Bioinformatics analysis of Drosophila and mouse databases revealed that caloric control of the Nhx1 orthologs DmNHE3 and NHE6, respectively, is also mediated by HDACs. We show that NHE6 is a target of the transcription factor cAMP-response element-binding protein (CREB), a known regulator of cellular responses to low-nutrient conditions, providing a molecular mechanism for nutrient- and HDAC-dependent regulation of endosomal pH. Of note, pharmacological targeting of the CREB pathway to increase NHE6 expression helped regulate endosomal pH and correct defective clearance of amyloid Aβ in an apoE4 astrocyte model of Alzheimer's disease. These observations from yeast, fly, mouse, and cell culture models point to an evolutionarily conserved mechanism for HDAC-mediated regulation of endosomal NHE expression. Our insights offer new therapeutic strategies for modulation of endolysosomal pH in fungal infection and human disease. © 2018 Prasad and Rao.

  6. Coaching af ph.d.-studerende

    DEFF Research Database (Denmark)

    Godskesen, Mirjam Irene

    Rapporten danner grundlag for at etablere et koncept for ph.d.-coaching. Erfaringerne fra et 2-årigt projekt om ph.d.-coaching i SCKK regi beskrives. De centrale temaer er tilrettelæggelse af den individuelle coaching, typiske temaer i coachingen og arbejdsdeling mellem coach og vejleder. Der er...

  7. Glutathione maintenance mitigates age-related susceptibility to redox cycling agents

    Directory of Open Access Journals (Sweden)

    Nicholas O. Thomas

    2016-12-01

    Full Text Available Isolated hepatocytes from young (4–6 mo and old (24–26 mo F344 rats were exposed to increasing concentrations of menadione, a vitamin K derivative and redox cycling agent, to determine whether the age-related decline in Nrf2-mediated detoxification defenses resulted in heightened susceptibility to xenobiotic insult. An LC50 for each age group was established, which showed that aging resulted in a nearly 2-fold increase in susceptibility to menadione (LC50 for young: 405 μM; LC50 for old: 275 μM. Examination of the known Nrf2-regulated pathways associated with menadione detoxification revealed, surprisingly, that NAD(PH: quinone oxido-reductase 1 (NQO1 protein levels and activity were induced 9-fold and 4-fold with age, respectively (p=0.0019 and p=0.018; N=3, but glutathione peroxidase 4 (GPX4 declined by 70% (p=0.0043; N=3. These results indicate toxicity may stem from vulnerability to lipid peroxidation instead of inadequate reduction of menadione semi-quinone. Lipid peroxidation was 2-fold higher, and GSH declined by a 3-fold greater margin in old versus young rat cells given 300 µM menadione (p2-fold reduction in cell death, suggesting that the age-related increase in menadione susceptibility likely stems from attenuated GSH-dependent defenses. This data identifies cellular targets for intervention in order to limit age-related toxicological insults to menadione and potentially other redox cycling compounds.

  8. Millimeter/submillimeter Spectroscopy of PH2CN ({\\tilde{X}} 1A') and CH3PH2 ({\\tilde{X}} 1A'): Probing the Complexity of Interstellar Phosphorus Chemistry

    Science.gov (United States)

    Halfen, D. T.; Clouthier, D. J.; Ziurys, L. M.

    2014-11-01

    Millimeter/submillimeter spectra of PH2CN ({\\tilde{X}} 1A') and CH3PH2 ({\\tilde{X}} 1A') have been recorded for the first time using direct absorption techniques. This work extends previous measurements of both molecules beyond the 10-50 GHz range. Both species were created in the presence of an AC discharge by the reaction of phosphorus vapor and either cyanogen and hydrogen (PH2CN) or methane (CH3PH2). Twelve rotational transitions of PH2CN were recorded over the region 305-422 GHz for asymmetry components Ka = 0 through 8. For CH3PH2, eight rotational transitions were measured from 210-470 GHz with Ka = 0 through 16; these spectra exhibited greater complexity due to the presence of internal rotation, which splits the Ka = 1, 2, and 3 asymmetry components into A and E states. Combined analyses of the millimeter/submillimeter and previous microwave data were performed for both molecules. For PH2CN, the spectra were fit with a Watson S-reduced asymmetric top Hamiltonian, resulting in more accurate rotational and centrifugal distortion constants. In the case of CH3PH2, an asymmetric top internal-rotation Hamiltonian was employed in the analysis, significantly improving the rotational and torsional parameters over previous microwave estimates. Searches for both molecules were subsequently conducted toward Sgr B2(N), using the 12 m telescope of the Arizona Radio Observatory (ARO). Neither species was identified, with abundance upper limits, relative to H2, of f (PH2CN/H2) PH2/H2) 2 and >200, respectively.

  9. An iridium oxide microelectrode for monitoring acute local pH changes of endothelial cells.

    Science.gov (United States)

    Ng, Shu Rui; O'Hare, Danny

    2015-06-21

    pH sensors were fabricated by anodically electrodepositing iridium oxide films (AEIROFs) onto microelectrodes on chips and coated with poly(ethyleneimine) (PEI) for mechanical stability. These demonstrate super-Nernstian response to pH from pH 4.0 to 7.7 in chloride-free phosphate buffer. The surface of the chip was coated with fibronectin for the attachment of porcine aortic endothelial cells (PAECs). The working capability of the pH sensor for monitoring acute local pH changes was investigated by stimulating the PAECs with thrombin. Our results show that thrombin induced acute extracellular acidification of PAECs and dissolution of fibronectin, causing the local pH to decrease. The use of PD98059, a mitogen-activated protein kinase (MAPK) inhibitor, reduced extracellular acidification and an increase in local pH was observed. This study shows that our pH sensors can facilitate the investigation of acute cellular responses to stimulation by monitoring the real-time, local pH changes of cells attached to the sensors.

  10. In vivo intracellular pH measurements in tobacco and Arabidopsis reveal an unexpected pH gradient in the endomembrane system.

    Science.gov (United States)

    Martinière, Alexandre; Bassil, Elias; Jublanc, Elodie; Alcon, Carine; Reguera, Maria; Sentenac, Hervé; Blumwald, Eduardo; Paris, Nadine

    2013-10-01

    The pH homeostasis of endomembranes is essential for cellular functions. In order to provide direct pH measurements in the endomembrane system lumen, we targeted genetically encoded ratiometric pH sensors to the cytosol, the endoplasmic reticulum, and the trans-Golgi, or the compartments labeled by the vacuolar sorting receptor (VSR), which includes the trans-Golgi network and prevacuoles. Using noninvasive live-cell imaging to measure pH, we show that a gradual acidification from the endoplasmic reticulum to the lytic vacuole exists, in both tobacco (Nicotiana tabacum) epidermal (ΔpH -1.5) and Arabidopsis thaliana root cells (ΔpH -2.1). The average pH in VSR compartments was intermediate between that of the trans-Golgi and the vacuole. Combining pH measurements with in vivo colocalization experiments, we found that the trans-Golgi network had an acidic pH of 6.1, while the prevacuole and late prevacuole were both more alkaline, with pH of 6.6 and 7.1, respectively. We also showed that endosomal pH, and subsequently vacuolar trafficking of soluble proteins, requires both vacuolar-type H(+) ATPase-dependent acidification as well as proton efflux mediated at least by the activity of endosomal sodium/proton NHX-type antiporters.

  11. Dissolution study of tremolite and anthophyllite: pH effect on the reaction kinetics

    International Nuclear Information System (INIS)

    Rozalen, M.; Ramos, M.E.; Gervilla, F.; Kerestedjian, T.; Fiore, S.; Huertas, F.J.

    2014-01-01

    Highlights: • Dissolution rates strongly depend on pH and it is different for each mineral. • Anthophyllite dissolves up to 8 times faster than tremolite in similar conditions. • SEM images show different particle breakage and carbonation effects at basic pHs. • Our results are a good background to develop remediation processes of contaminated sites. - Abstract: The effect of pH on the kinetics of tremolite and anthophyllite dissolution was investigated at 25 °C in batch reactors over the pH range of 1–13.5, in inorganic buffered solutions. Dissolution rates were obtained based on the release of Si and Mg. Results obtained in this study show different behaviors for both minerals. For tremolite, dissolution rates show a noticeable dependence on pH between 1 and 8, decreasing as pH increases and reaching a minimum around neutral conditions. At basic pH this dependence becomes even stronger, but dissolution takes place together with collateral effects of saturation and carbonation. A preferential release of Ca and Mg is observed in acid media, lowering the Mg/Si ratio to the extent that Mg solubility decreases with pH. For anthophyllite, dissolution rates also show a strong dependence on pH, between 1 and 9.5. At the same pH, anthophyllite dissolves up to 8 times faster than tremolite. For pH > 9.5 this dependence is smooth, and it is probably associated with effects of saturation and carbonation. Dissolution is also non-stoichiometric with a faster release of Mg with respect to Si in acid media. SEM observations show differences in the breakage mechanism of the fibers. The anthophyllite particle breakage during dissolution consists of the splitting of bundle fibers parallel to the fiber longitudinal direction. However, for tremolite, other than fiber splitting, particles shorten induced by coalescence of etch pits developed perpendicular to c axe

  12. Can cycling safety be improved by opening all unidirectional cycle paths for cycle traffic in both directions? A theoretical examination of available literature and data.

    Science.gov (United States)

    Methorst, Rob; Schepers, Paul; Kamminga, Jaap; Zeegers, Theo; Fishman, Elliot

    2017-08-01

    Many studies have found bicycle-motor vehicle crashes to be more likely on bidirectional cycle paths than on unidirectional cycle paths because drivers do not expect cyclists riding at the right side of the road. In this paper we discuss the hypothesis that opening all unidirectional cycle paths for cycle traffic in both directions prevent this lack of expectancy and accordingly improves cycling safety. A new national standard requires careful consideration because a reversal is difficult once cyclists are used to their new freedom of route choice. We therefore explored the hypothesis using available data, research, and theories. The results show that of the length of cycle paths along distributor roads in the Netherlands, 72% is bidirectional. If drivers would become used to cyclists riding at the left side of the road, this result raises the question of why bidirectional cycle paths in the Netherlands still have a poor safety record compared to unidirectional cycle paths. Moreover, our exploration suggested that bidirectional cycle paths have additional safety problems. It increases the complexity of unsignalized intersections because drivers have to scan more directions in a short period of time. Moreover, there are some indications that the likelihood of frontal crashes between cyclists increases. We reject the hypothesis that opening all unidirectional cycle paths for cycle traffic in both directions will improve cycle safety. We recommend more attention for mitigating measures given the widespread application of bidirectional cycle paths in the Netherlands. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. pH Sensing and Regulation in Cancer

    OpenAIRE

    Mehdi eDamaghi; Jonathan W. Wojtkowiak; Robert J. Gillies

    2013-01-01

    Cells maintain intracellular pH (pHi) within a narrow range (7.1-7.2) by controlling membrane proton pumps and transporters whose activity is set by intra-cytoplasmic pH sensors. These sensors have the ability to recognize and induce cellular responses to maintain the intracellular pH, often at the expense of acidifying the extracellular pH. In turn, extracellular acidification impacts cells via specific acid-sensing ion channels (ASICs) and proton-sensing G-protein coupled receptors (GPCRs...

  14. Methodologically controlled variations in laboratory and field pH measurements in waterlogged soils

    DEFF Research Database (Denmark)

    Elberling, Bo; Matthiesen, Henning

    2007-01-01

    artefacts is critical. But the study includes agricultural and forest soils for comparison. At a waterlogged site, Laboratory results were compared with three different field methods: calomel pH probes inserted in the soil from pits, pH measurements of soil solution extracted from the soil, and pH profiles...... using a solid-state pH electrode pushed into the soil from the surface. Comparisons between in situ and laboratory methods revealed differences of more than 1 pH unit. The content of dissolved ions in soil solution and field observations of O2 and CO2 concentrations were used in the speciation model...... PHREEQE in order to predict gas exchange processes. Changes in pH in soil solution following equilibrium in the laboratory could be explained mainly by CO2 degassing. Only soil pH measured in situ using either calomel or solid-state probes inserted directly into the soil was not affected by gas exchange...

  15. Assessment of the Effect of Fruit (Apple and Plain Yoghurt Consumption on Plaque pH

    Directory of Open Access Journals (Sweden)

    Peyvand Moeiny

    2017-09-01

    Full Text Available Introduction: Nowadays, thanks to improvements in fruit yoghurt tastes, more tendencies are seen in their consumption especially among children. Therefore, their cariogenicity evaluation as healthy snacks is important. The goal of this study was the assessment of the consumption effect of two kinds of Iranian fruit (apple and plain yoghurts on dental plaque PH. Methods: In this experimental study, 10 healthy dentistry students were selected upon inclusion criteria. Plaque pH in the certain areas of the mouth was measured by microelectrode and digital pH meter. PH was measured at the baseline and intervals of 2, 5, 7, 10, 15, 20, 30, 40, 50 and 60 minutes after eating test products: fruit yoghurt (apple and plain Yoghurt. For positive control group, just the baseline PH and at intervals of 2 and 5 min after swishing with 10% sucrose solutions were recorded. The results were analyzed using repeated measures ANOVA. Results: Lowest pH was obtained after fruit yoghurt consumption followed by plain yoghurt and %10 sucrose solution and the plaque PH difference was significant (P=0.05. Furthermore, time duration which remained below the critical pH was longer after consuming fruit yoghurt. Conclusion: Both kinds of yoghurts were considered cariogenic since plaque pH drop below critical points. Average of plaque pH after consuming fruit yoghurt was significantly lower in almost all the time intervals

  16. Salivary pH as a marker of plasma adiponectin concentrations in Women.

    Science.gov (United States)

    Tremblay, Monique; Loucif, Yacine; Methot, Julie; Brisson, Diane; Gaudet, Daniel

    2012-02-03

    Plasma adiponectin is a significant correlate of the pro-inflammatory cardiometabolic risk profile associated with obesity and type 2 diabetes. Salivary pH is influenced by several cardiometabolic risk components such as inflammation, oxidation and numerous oral and systemic health modulators, including the menopausal status. This study aimed to assess the association between plasma adiponectin concentrations and salivary pH in women according to the menopausal status. Unstimulated saliva collection was performed in 151 Caucasian women of French-Canadian origin (53 premenopausal women (PMW) and 98 menopausal women (MW)). Student's t test, ANOVA and linear regression models were used to assess the association between plasma adiponectin concentrations and salivary pH. Plasma adiponectin levels increased as a function of salivary pH in the whole sample and among MW (r = 0.29 and r = 0.36, p salivary pH (R2) was 10.8% (p salivary pH quartiles (p = 0.005). These results suggest that salivary pH is a significant correlate of plasma adiponectin levels in women. With the increasing prevalence of type 2 diabetes and obesity, new technologies should be developed to more easily monitor health status, disease onset and progression. Salivary pH, a simple, inexpensive and non-invasive measure, could be a very promising avenue.

  17. The Influence of pH on the Scleroglucan and Scleroglucan/Borax Systems.

    Science.gov (United States)

    Mazzuca, Claudia; Bocchinfuso, Gianfranco; Palleschi, Antonio; Conflitti, Paolo; Grassi, Mario; Di Meo, Chiara; Alhaique, Franco; Coviello, Tommasina

    2017-03-09

    The effects that an increase of environmental pH has on the triple helix of scleroglucan (Sclg) and on the Sclg/borax hydrogel are reported. Rheological experiments show that the hydrogel is less sensitive to pH increase than Sclg alone, while at pH = 14 a dramatic viscosity decrease takes place for both systems. This effect is evidenced also by the reduced water uptake and anisotropic elongation detected, at pH = 14, by the swelling behaviour of tablets prepared with the Sclg/borax system. On the opposite, a different behaviour was observed with guar gum and locust bean gum tablets, tested as reference polysaccharides. The effect of pH on the structure of Sclg and Sclg/borax was investigated also by means of spectroscopic approaches based on the interaction between Congo red (CR) and the Sclg triple helix. Obtained results indicated that the CR absorbance maximum is shifted as a function of pH and by the presence of borax. Principal component analysis allowed very precise identification of the pH value at which the Sclg helix collapses. Molecular dynamics simulations of the Sclg/borax-CR complex indicated that, at physiological pH, only a few ordered configurations are populated, according to the induced circular dichroism (CD) spectrum evidence.

  18. The Influence of pH on the Scleroglucan and Scleroglucan/Borax Systems

    Directory of Open Access Journals (Sweden)

    Claudia Mazzuca

    2017-03-01

    Full Text Available The effects that an increase of environmental pH has on the triple helix of scleroglucan (Sclg and on the Sclg/borax hydrogel are reported. Rheological experiments show that the hydrogel is less sensitive to pH increase than Sclg alone, while at pH = 14 a dramatic viscosity decrease takes place for both systems. This effect is evidenced also by the reduced water uptake and anisotropic elongation detected, at pH = 14, by the swelling behaviour of tablets prepared with the Sclg/borax system. On the opposite, a different behaviour was observed with guar gum and locust bean gum tablets, tested as reference polysaccharides. The effect of pH on the structure of Sclg and Sclg/borax was investigated also by means of spectroscopic approaches based on the interaction between Congo red (CR and the Sclg triple helix. Obtained results indicated that the CR absorbance maximum is shifted as a function of pH and by the presence of borax. Principal component analysis allowed very precise identification of the pH value at which the Sclg helix collapses. Molecular dynamics simulations of the Sclg/borax–CR complex indicated that, at physiological pH, only a few ordered configurations are populated, according to the induced circular dichroism (CD spectrum evidence.

  19. Fiber optic pH sensor with self-assembled polymer multilayer nanocoatings.

    Science.gov (United States)

    Shao, Li-Yang; Yin, Ming-Jie; Tam, Hwa-Yaw; Albert, Jacques

    2013-01-24

    A fiber-optic pH sensor based on a tilted fiber Bragg grating (TFBG) with electrostatic self-assembly multilayer sensing film is presented. The pH sensitive polymeric film, poly(diallyldimethylammonium chloride) (PDDA) and poly(acrylic acid) (PAA) was deposited on the circumference of the TFBG with the layer-by-layer (LbL) electrostatic self-assembly technique. The PDDA/PAA film exhibits a reduction in refractive index by swelling in different pH solutions. This effect results in wavelength shifts and transmission changes in the spectrum of the TFBG. The peak amplitude of the dominant spectral fringes over a certain window of the transmission spectrum, obtained by FFT analysis, has a near-linear pH sensitivity of 117 arbitrary unit (a.u.)/pH unit and an accuracy of ±1 a.u. (in the range of pH 4.66 to pH 6.02). The thickness and surface morphology of the sensing multilayer film were characterized to investigate their effects on the sensor's performance. The dynamic response of the sensor also has been studied (10 s rise time and 18 s fall time for a sensor with six bilayers of PDDA/PAA).

  20. Cycle for innovative nuclear Gen 4. systems=; Cycle des systemes du futur

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    In the framework of the development of nuclear systems of the 4. generation, the preliminary and schematic reprocessing goals are a cleaning of fission products without a priori separation of the different actinides. The objective of the workshop is to exchange information about the potential efficiency of innovative fuel processing treatments in order to evaluate the impact of impurities on the design of the fuel during its re-fabrication and re-introduction inside the reactor, and on the materials and systems. This document gathers the slides of the 18 presentations given at this workshop: 1 - from the PWR fuel to the closed cycle fast spectrum concepts of generation 4 systems (P. Anzieu, F. Carre, Ph. Brossard, M. Delpech); 2 - the double strata scenarios: objectives and characteristics (S. David and F. Varaine); 3 - why a molten salts thorium file (D. Heuer); 4 - the common 'molten salts' research program of the CNRS (D. Heuer, S. Sanchez); 5 - the hydro-metallurgical reprocessing, the knowledge gained and the statuses of the 5. PCRD, synthesis of the OECD works (C. Madic); 6 - pyro-chemistry: Pyropep status (H. Boussier); 7 - technological bolts identified during the Most project of the 5. PCRD (C. Renault, Ch. Le Brun, M. Delpech and C. Garzenne); 8 - the molten salt reactor concept and its reprocessing options, expected efficiencies (L. Mathieu); 9 - methodology of evaluation of pyro-chemical fuel reprocessing schemes (H. Boussier); 10 - molten salt reactor, design-aided tools for the reactor and the reprocessing plant (O. Gastaldi, E. Walle, O. Koberl, D. Lecarpentier); 11 - status of CEA's prospective studies for the front-end of the fuel reprocessing process/dry ways (S. Bourg); 12 - results of activity coefficient measurements in liquid metals (J. Finne, E. Walle, G. Picard, S. Sanchez and O. Conocar); 13 - potentialities of electrolytic separation and liquid-liquid extraction processes (molten salts/molten metal) for the multi

  1. The panacea toolbox of a PhD biomedical student.

    Science.gov (United States)

    Skaik, Younis

    2014-01-01

    Doing a PhD (doctor of philosophy) for the sake of contribution to knowledge should give the student an immense enthusiasm through the PhD period. It is the time in one's life that one spends to "hit the nail on the head" in a specific area and topic of interest. A PhD consists mostly of hard work and tenacity; however, luck and genius might also play a little role. You can pass all PhD phases without having both luck and genius. The PhD student should have pre-PhD and PhD toolboxes, which are "sine quibus non" for getting successfully a PhD degree. In this manuscript, the toolboxes of the PhD student are discussed.

  2. pH dominates variation in tropical soil archaeal diversity and community structure.

    Science.gov (United States)

    Tripathi, Binu M; Kim, Mincheol; Lai-Hoe, Ang; Shukor, Nor A A; Rahim, Raha A; Go, Rusea; Adams, Jonathan M

    2013-11-01

    Little is known of the factors influencing soil archaeal community diversity and composition in the tropics. We sampled soils across a range of forest and nonforest environments in the equatorial tropics of Malaysia, covering a wide range of pH values. DNA was PCR-amplified for the V1-V3 region of the 16S rRNA gene, and 454-pyrosequenced. Soil pH was the best predictor of diversity and community composition of Archaea, being a stronger predictor than land use. Archaeal OTU richness was highest in the most acidic soils. Overall archaeal abundance in tropical soils (determined by qPCR) also decreased at higher pH. This contrasts with the opposite trend previously found in temperate soils. Thaumarcheota group 1.1b was more abundant in alkaline soils, whereas group 1.1c was only detected in acidic soils. These results parallel those found in previous studies in cooler climates, emphasizing niche conservatism among broad archaeal groups. Among the most abundant operational taxonomic units (OTUs), there was clear evidence of niche partitioning by pH. No individual OTU occurred across the entire range of pH values. Overall, the results of this study show that pH plays a major role in structuring tropical soil archaeal communities. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  3. Water balance creates a threshold in soil pH at the global scale

    Science.gov (United States)

    Slessarev, E. W.; Lin, Y.; Bingham, N. L.; Johnson, J. E.; Dai, Y.; Schimel, J. P.; Chadwick, O. A.

    2016-12-01

    Soil pH regulates the capacity of soils to store and supply nutrients, and thus contributes substantially to controlling productivity in terrestrial ecosystems. However, soil pH is not an independent regulator of soil fertility—rather, it is ultimately controlled by environmental forcing. In particular, small changes in water balance cause a steep transition from alkaline to acid soils across natural climate gradients. Although the processes governing this threshold in soil pH are well understood, the threshold has not been quantified at the global scale, where the influence of climate may be confounded by the effects of topography and mineralogy. Here we evaluate the global relationship between water balance and soil pH by extracting a spatially random sample (n = 20,000) from an extensive compilation of 60,291 soil pH measurements. We show that there is an abrupt transition from alkaline to acid soil pH that occurs at the point where mean annual precipitation begins to exceed mean annual potential evapotranspiration. We evaluate deviations from this global pattern, showing that they may result from seasonality, climate history, erosion and mineralogy. These results demonstrate that climate creates a nonlinear pattern in soil solution chemistry at the global scale; they also reveal conditions under which soils maintain pH out of equilibrium with modern climate.

  4. Bipolar mood cycles and lunar tidal cycles.

    Science.gov (United States)

    Wehr, T A

    2018-04-01

    In 17 patients with rapid cycling bipolar disorder, time-series analyses detected synchronies between mood cycles and three lunar cycles that modulate the amplitude of the moon's semi-diurnal gravimetric tides: the 14.8-day spring-neap cycle, the 13.7-day declination cycle and the 206-day cycle of perigee-syzygies ('supermoons'). The analyses also revealed shifts among 1:2, 1:3, 2:3 and other modes of coupling of mood cycles to the two bi-weekly lunar cycles. These shifts appear to be responses to the conflicting demands of the mood cycles' being entrained simultaneously to two different bi-weekly lunar cycles with slightly different periods. Measurements of circadian rhythms in body temperature suggest a biological mechanism through which transits of one of the moon's semi-diurnal gravimetric tides might have driven the patients' bipolar cycles, by periodically entraining the circadian pacemaker to its 24.84-h rhythm and altering the pacemaker's phase-relationship to sleep in a manner that is known to cause switches from depression to mania.

  5. pH controls over methanogenesis and iron reduction along soil depth profile in Arctic tundra

    Science.gov (United States)

    Zheng, J.; Gu, B.; Wullschleger, S. D.; Graham, D. E.

    2017-12-01

    Increasing soil temperature in the Arctic is expected to accelerate rates of soil organic matter decomposition. However, the magnitude of this impact is uncertain due to the many physical, chemical, and biological processes that control the decomposition pathways. Varying soil redox conditions present a key control over pathways of organic matter decomposition by diverting the flow of reductants among different electron accepting processes and further driving acid-base reactions that alter soil pH. In this study we investigated the pH controls over anaerobic carbon mineralization, methanogenesis, Fe(III) reduction and the interplay between these processes across a range of pH and redox conditions. pH manipulation experiments were conducted by incubating soils representing organic, mineral, cryoturbated transitional layers and permafrost. In the experiments we sought to understand (1) if methanogenesis or Fe(III) reduction had similar pH optima; (2) if this pH response also occurs at `upstream' fermentation process; and (3) if pH alters organo-mineral association or organic matter sorption and desorption and its availability for microbial degradation. Our preliminary results suggest that the common bell-shaped pH response curve provides a good fit for both Fe(III) reduction and methanogenesis, with optimum pH at 6.0-7.0. Exceptions to this were found in transitional layer where methanogenesis rates positively correlated with increasing pH, with maximum rates measured at pH 8.5. It is likely that the transitional layer harbors distinct groups of methanogens that prefer a high pH. Variations in the optimum pH of Fe(III) reduction and methanogenesis may play a significant role in regulating organic matter decomposition pathways and thus greenhouse gas production in thawing soils. These results support biogeochemical modeling efforts to accurately simulate organic matter decomposition under changing redox and pH conditions.

  6. Evaluating high pH for control of dreissenid mussels

    Directory of Open Access Journals (Sweden)

    Dave Evans

    2013-04-01

    Full Text Available Two field experiments were carried out using a custom built flow-through laboratory to test the effect of elevated pH on dreissenid musselsas a potential control method. Both experiments tested the ability of dreissenid pediveligers to settle under conditions of elevated pH and thelong-term survival of adult dreissenids under the same conditions. The two experimental sites had different water quality and differentspecies of dreissenids present. The settlement of quagga mussel pediveligers at the lower Colorado River was inhibited with increasing pH.At the maximum achieved pH of 9.1, there was approximately 90% reduction compared to the maximum settlement observed in the controls.Since the settlement was almost as low in pH 8.9 as at pH 9.1, the inhibition in settlement may have been due to the presence of a precipitateformed under high pH conditions rather than the increase in background pH. No mortality of quagga mussel adults was observed in theexperimental pH levels at the lower Colorado River. At San Justo Reservoir, zebra mussel settlement decreased with increasing pH. Newsettlement was almost entirely absent at the highest pH tested (pH 9.6. The observed mortality of adult zebra mussels was low, but did tendto increase with increasing pH. We also tested the response of adult zebra mussels to short-term exposure to very high pH levels (i.e. pH 10,11, and 12. Adult mussels in poor physical condition experienced 90% mortality after 12 hours at pH 12. For unstressed adult zebra mussels,90% mortality was reached after 120 hours at pH 12. Significant mortalities were also observed both at pH 10 and pH 11. From this study,we conclude that pH elevation could be used both as a preventative treatment to eliminate settlement by dreissenid mussels and as an end ofseason treatment to eliminate adults. The high pH treatment would have to be tailored to the site water quality to prevent formation ofprecipitate during treatment and to minimize corrosive

  7. Graphene Channel Liquid Container Field Effect Transistor as ph Sensor

    International Nuclear Information System (INIS)

    Li, X.; Shi, J.; Pang, J.; Liu, W.; Wang, X.; Liu, H.

    2014-01-01

    Graphene channel liquid container field effect transistor ph sensor with interdigital micro trench for liquid ion testing is presented. Growth morphology and ph sensing property of continuous few-layer graphene (FLG) and quasi-continuous monolayer graphene (MG) channels are compared. The experiment results show that the source-to-drain current of the graphene channel FET has a significant and fast response after adsorption of the measured molecule and ion at the room temperature; at the same time, the FLG response time is less than 4 s. The resolution of MG (0.01) on ph value is one order of magnitude higher than that of FLG (0.1). The reason is that with fewer defects, the MG is more likely to adsorb measured molecule and ion, and the molecules and ions can make the transport property change. The output sensitivities of MG are from 34.5% to 57.4% when the ph value is between 7 and 8, while sensitivity of FLG is 4.75% when the Ph=6. The sensor fabrication combines traditional silicon technique and flexible electronic technology and provides an easy way to develop graphene-based electrolyte gas sensor or even biological sensors.

  8. pH Control Enables Simultaneous Enhancement of Nitrogen Retention and N2O Reduction in Shewanella loihica Strain PV-4

    Directory of Open Access Journals (Sweden)

    Hayeon Kim

    2017-09-01

    Full Text Available pH has been recognized as one of the key environmental parameters with significant impacts on the nitrogen cycle in the environment. In this study, the effects of pH on NO3–/NO2– fate and N2O emission were examined with Shewanella loihica strain PV-4, an organism with complete denitrification and respiratory ammonification pathways. Strain PV-4 was incubated at varying pH with lactate as the electron donor and NO3–/NO2– and N2O as the electron acceptors. When incubated with NO3– and N2O at pH 6.0, transient accumulation of N2O was observed and no significant NH4+ production was observed. At pH 7.0 and 8.0, strain PV-4 served as a N2O sink, as N2O concentration decreased consistently without accumulation. Respiratory ammonification was upregulated in the experiments performed at these higher pH values. When NO2– was used in place of NO3–, neither growth nor NO2– reduction was observed at pH 6.0. NH4+ was the exclusive product from NO2– reduction at both pH 7.0 and 8.0 and neither production nor consumption of N2O was observed, suggesting that NO2– regulation superseded pH effects on the nitrogen-oxide dissimilation reactions. When NO3– was the electron acceptor, nirK transcription was significantly upregulated upon cultivation at pH 6.0, while nrfA transcription was significantly upregulated at pH 8.0. The highest level of nosZ transcription was observed at pH 6.0 and the lowest at pH 8.0. With NO2– as the electron acceptor, transcription profiles of nirK, nrfA, and nosZ were statistically indistinguishable between pH 7.0 and 8.0. The transcriptions of nirK and nosZ were severely downregulated regardless of pH. These observations suggested that the kinetic imbalance between N2O production and consumption, but neither decrease in expression nor activity of NosZ, was the major cause of N2O accumulation at pH 6.0. The findings also suggest that simultaneous enhancement of nitrogen retention and N2O emission reduction may be

  9. Antimicrobial activity and pH of a endodontic sealer containing MTA

    DEFF Research Database (Denmark)

    Maliza, Amanda GA; de Andrade, Flaviana Bombarda; Arias, Marcela C

    Objective: To investigate the antimicrobial activity, calcium release, and pH of a new mineral trioxide aggregate endodontic sealer when compared to endodontic sealers containing calcium hydroxide and/or epoxy resin. Method: Specimens were fabricated from MTA Fillapex, Sealer 26, Sealapex, and AH...... Plus immediately, 24 or 48 hours prior to the tests. The antimicrobial activity against Enterococcus faecalis and Candida albicans was evaluated by the direct contact and the agar diffusion methods. Calcium release was determined by atomic absorption spectrometry. The pH from solutions containing...... in solution with an alkaline pH. Conclusion: The new mineral trioxide aggregate endodontic sealer presented higher antimicrobial activity when compared to the sealers containing calcium hydroxide and/or epoxy resin. As for pH and calcium release, the sealers containing calcium hydroxide resulted in presented...

  10. PER PhDs & Bachelor's Degrees

    Science.gov (United States)

    White, Susan C.

    2017-01-01

    Recently, the editor remarked to me that physics departments that offered a PhD with a specialization in Physics Education Research (PER) seemed to graduate more bachelor's degree recipients than those physics PhD departments that did not have the specialization. I was not convinced. That led to quite a bit of discussion between us. He compiled a…

  11. Early Development of the Threespine Stickleback in Relation to Water pH

    Directory of Open Access Journals (Sweden)

    Olivier Glippa

    2017-12-01

    Full Text Available Ocean acidification is a growing environmental problem, and there is a need to investigate how the decreasing pH will affect marine organisms. Here we studied the effects of lowered pH on the growth and development of the threespine stickleback (Gasterosteus aculeatus eggs. Adult fish, collected from the natural environment, were allowed to mate in aquaria and the newly produced eggs were incubated in an experiment. Eggs and larvae from ambient conditions (produced in the laboratory were reared at three different pH concentrations (control: pH 7.8; and reduced pH treatments: pH 7.5 and 7.0 for 21 days in the laboratory. Dissolved oxygen concentration (8.1 ± 0.1 mg l−1 and temperature (18.6 ± 0.02°C were monitored regularly. Then, egg diameter, larval length, weight and survival were measured. There was no relationship between egg diameter and pH or oxygen, but a negative relationship was found with temperature. Survival of larvae was not affected by pH or temperature, whereas dissolved oxygen concentration had a positive effect on number of survivors. The pH did not have a significant effect on the final larval length on day 21, but interacted significantly with dissolved oxygen. Higher temperatures were found to have a positive effect on the final larval length and weight. Larval weight, on the other hand, was not related to pH nor oxygen. Coastal zones are characterized by pH levels that fluctuate due to natural processes, such as upwelling and river runoff. Our results suggest that the threespine stickleback larvae are well adapted to the different pHs tested, and egg development will likely not be affected by decreasing pH, but even slight temperature and oxygen changes can have a great impact on the threespine stickleback development.

  12. Direct reduction of N-acetoxy-PhIP by tea polyphenols: a possible mechanism for chemoprevention against PhIP-DNA adduct formation

    International Nuclear Information System (INIS)

    Lin Dongxin; Thompson, Patricia A.; Teitel, Candee; Chen Junshi; Kadlubar, Fred F.

    2003-01-01

    The chemopreventive effect of tea against 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-DNA adduct formation and its mechanism were studied. Rats were exposed to freshly prepared aqueous extracts of green tea (3% (w/v)) as the sole source of drinking water for 10 days prior to administration with a single dose of PhIP (10 mg/kg body weight) by oral gavage. PhIP-DNA adducts in the liver, colon, heart, and lung were measured using the 32 P-postlabelling technique. Rats pre-treated with tea and given PhIP 20 h before sacrifice had significantly reduced levels of PhIP-DNA adducts as compared with controls given PhIP alone. The possible mechanism of protective effect of tea on PhIP-DNA adduct formation was then examined in vitro. It was found that an aqueous extract of green and black tea, mixtures of green and black tea polyphenols, as well as purified polyphenols could strongly inhibit the DNA binding of N-acetoxy-PhIP, a putative ultimate carcinogen of PhIP formed in vivo via metabolic activation. Among these, epigallocatechin gallate was exceptionally potent. HPLC analyses of these incubation mixtures containing N-acetoxy-PhIP and the tea polyphenols each revealed the production of the parent amine, PhIP, indicating the involvement of a redox mechanism. In view of the presence of relatively high levels of tea polyphenols in rat and human plasma after ingestion of tea, this study suggests that direct reduction of the ultimate carcinogen N-acetoxy-PhIP by tea polyphenols is likely to be involved in the mechanism of chemoprotection of tea against this carcinogen

  13. pH preference and avoidance responses of adult brook trout Salvelinus fontinalis and brown trout Salmo trutta.

    Science.gov (United States)

    Fost, B A; Ferreri, C P

    2015-03-01

    The pH preferred and avoided by wild, adult brook trout Salvelinus fontinalis and brown trout Salmo trutta was examined in a series a laboratory tests using gradual and steep-gradient flow-through aquaria. The results were compared with those published for the observed segregation patterns of juvenile S. fontinalis and S. trutta in Pennsylvania streams. The adult S. trutta tested showed a preference for pH 4·0 while adult S. fontinalis did not prefer any pH within the range tested. Salmo trutta are not found in Pennsylvania streams with a base-flow pH < 5·8 which suggests that S. trutta prefer pH well above 4·0. Adult S. trutta displayed a lack of avoidance at pH below 5·0, as also reported earlier for juveniles. The avoidance pH of wild, adult S. fontinalis (between pH 5·5 and 6·0) and S. trutta (between pH 6·5 and 7·0) did not differ appreciably from earlier study results for the avoidance pH of juvenile S. fontinalis and S. trutta. A comparison of c.i. around these avoidance estimates indicates that avoidance pH is similar among adult S. fontinalis and S. trutta in this study. The limited overlap of c.i. for avoidance pH values for the two species, however, suggests that some S. trutta will display avoidance at a higher pH when S. fontinalis will not. The results of this study indicate that segregation patterns of adult S. fontinalis and S. trutta in Pennsylvania streams could be related to pH and that competition with S. trutta could be mediating the occurrence of S. fontinalis at some pH levels. © 2015 The Fisheries Society of the British Isles.

  14. pH variations during diafiltration due to buffer nonidealities.

    Science.gov (United States)

    Baek, Youngbin; Yang, Deyu; Singh, Nripen; Arunkumar, Abhiram; Ghose, Sanchayita; Li, Zheng Jian; Zydney, Andrew L

    2017-11-01

    Diafiltration is used for final formulation of essentially all biotherapeutics. Several studies have demonstrated that buffer/excipient concentrations in the final diafiltered product can be different than that in the diafiltration buffer due to interactions between buffer species and the protein product. However, recent work in our lab has shown variations in solution pH that are largely independent of the protein concentration during the first few diavolumes. Our hypothesis is that these pH variations are due to nonidealities in the acid-base equilibrium coefficient. A model was developed for the diafiltration process accounting for the ionic strength dependence of the pK a . Experimental results obtained using phosphate and histidine buffers were in excellent agreement with model predictions. A decrease in ionic strength leads to an increase in the pK a for the phosphate buffer, causing a shift in the solution pH, even under conditions where the initial feed and the diafiltration buffer are at the same pH. This effect could be eliminated by matching the ionic strength of the feed and diafiltration buffer. The experimental data and model provide new insights into the factors controlling the pH profile during diafiltration processes. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1555-1560, 2017. © 2017 American Institute of Chemical Engineers.

  15. Contribution of the tricarboxylic acid (TCA) cycle and the glyoxylate shunt in Saccharomyces cerevisiae to succinic acid production during dough fermentation.

    Science.gov (United States)

    Rezaei, Mohammad N; Aslankoohi, Elham; Verstrepen, Kevin J; Courtin, Christophe M

    2015-07-02

    Succinic acid produced by yeast during bread dough fermentation can significantly affect the rheological properties of the dough. By introducing mutations in the model S288C yeast strain, we show that the oxidative pathway of the TCA cycle and the glyoxylate shunt contribute significantly to succinic acid production during dough fermentation. More specifically, deletion of ACO1 and double deletion of ACO1 and ICL1 resulted in a 36 and 77% decrease in succinic acid levels in fermented dough, respectively. Similarly, double deletion of IDH1 and IDP1 decreased succinic acid production by 85%, while also affecting the fermentation rate. By contrast, double deletion of SDH1 and SDH2 resulted in a two-fold higher succinic acid accumulation compared to the wild-type. Deletion of fumarate reductase activity (FRD1 and OSM1) in the reductive pathway of the TCA cycle did not affect the fermentation rate and succinic acid production. The changes in the levels of succinic acid produced by mutants Δidh1Δidp1 (low level) and Δsdh1Δsdh2 (high level) in fermented dough only resulted in small pH differences, reflecting the buffering capacity of dough at a pH of around 5.1. Moreover, Rheofermentometer analysis using these mutants revealed no difference in maximum dough height and gas retention capacity with the dough prepared with S288C. The impact of the changed succinic acid profile on the organoleptic or antimicrobial properties of bread remains to be demonstrated. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Effects of metals on life cycle parameters of the earthworm Eisenia fetida exposed to field-contaminated, metal-polluted soils

    International Nuclear Information System (INIS)

    Nahmani, Johanne; Hodson, Mark E.; Black, Stuart

    2007-01-01

    Two control and eight field-contaminated, metal-polluted soils were inoculated with Eisenia fetida (Savigny, 1826). Three, 7, 14, 21, 28 and 42 days after inoculation, earthworm survival, body weight, cocoon production and hatching rate were measured. Seventeen metals were analysed in E. fetida tissue, bulk soil and soil solution. Soil organic carbon content, texture, pH and cation exchange capacity were also measured. Cocoon production and hatching rate were more sensitive to adverse conditions than survival or weight change. Soil properties other than metal concentration impacted toxicity. The most toxic soils were organic-poor (1-10 g C kg -1 ), sandy soils (c. 74% sand), with intermediate metal concentrations (e.g. 7150-13,100 mg Pb kg -1 , 2970-53,400 mg Zn kg -1 ). Significant relationships between soil properties and the life cycle parameters were determined. The best coefficients of correlation were generally found for texture, pH, Ag, Cd, Mg, Pb, Tl, and Zn both singularly and in multivariate regressions. Studies that use metal-amended artificial soils are not useful to predict toxicity of field multi-contaminated soils. - Soil pH, organic carbon content and texture can exert a greater influence on earthworm life cycle parameters than soil metal concentrations at metal-contaminated sites

  17. Effects of metals on life cycle parameters of the earthworm Eisenia fetida exposed to field-contaminated, metal-polluted soils

    Energy Technology Data Exchange (ETDEWEB)

    Nahmani, Johanne [Department of Soil Science, School of Human and Environmental Sciences, University of Reading, Whiteknights, Reading, Berkshire RG6 6DW (United Kingdom)]. E-mail: nahmani@univ-metz.fr; Hodson, Mark E. [Department of Soil Science, School of Human and Environmental Sciences, University of Reading, Whiteknights, Reading, Berkshire RG6 6DW (United Kingdom)]. E-mail: m.e.hodson@reading.ac.uk; Black, Stuart [Department of Archaeology, School of Human and Environmental Sciences, Whiteknights, University of Reading, Reading RG6 6DW (United Kingdom)

    2007-09-15

    Two control and eight field-contaminated, metal-polluted soils were inoculated with Eisenia fetida (Savigny, 1826). Three, 7, 14, 21, 28 and 42 days after inoculation, earthworm survival, body weight, cocoon production and hatching rate were measured. Seventeen metals were analysed in E. fetida tissue, bulk soil and soil solution. Soil organic carbon content, texture, pH and cation exchange capacity were also measured. Cocoon production and hatching rate were more sensitive to adverse conditions than survival or weight change. Soil properties other than metal concentration impacted toxicity. The most toxic soils were organic-poor (1-10 g C kg{sup -1}), sandy soils (c. 74% sand), with intermediate metal concentrations (e.g. 7150-13,100 mg Pb kg{sup -1}, 2970-53,400 mg Zn kg{sup -1}). Significant relationships between soil properties and the life cycle parameters were determined. The best coefficients of correlation were generally found for texture, pH, Ag, Cd, Mg, Pb, Tl, and Zn both singularly and in multivariate regressions. Studies that use metal-amended artificial soils are not useful to predict toxicity of field multi-contaminated soils. - Soil pH, organic carbon content and texture can exert a greater influence on earthworm life cycle parameters than soil metal concentrations at metal-contaminated sites.

  18. Diagnostic significance of pleural fluid pH and pCO2

    Directory of Open Access Journals (Sweden)

    K.E. Sobhey

    2015-10-01

    Results: We conducted this study on 50 patients with pleural effusions of different causes. The patients were classified into 5 groups according to the cause. For all the patients, measurement of pleural pH, pCO2, pO2, HCO3, protein, LDH, glucose and WBC was done. We observed lowest pH in complicated parapneumonic effusion (empyema 6.80 ± 0.15 and highest pH was observed in transudative effusion 7.47 ± 0.07. Tuberculous effusion has pH lower than pH of malignant effusion 7.17 ± 0.017 and 7.39 ± 0.08, respectively. Post pleurodesis malignant effusion has pH lower than pH of malignant effusion 7.28 ± 0.17 and 7.39 ± 0.08, respectively. There is a strong inverse correlation between pH and pCO2, WBC, LDH and protein (r = −0.813 and p < 0.001, (r = −0.796 and p, 0.001, (r = −0.829 and p, 0.001 and (r = −.837 and p, 0.001, respectively. While there is a weak correlation between pH and glucose of pleural fluid (r = 0.249 and p = 0.066. The highest increase of PNL numbers was in empyema (20169 ± 8094.8 cells/cc.The highest increase of lymphocytes was in malignant effusions (4285.00 ± 2948.20 cells/cc and tuberculous effusion (3977.7 ± 3169 cells/cc.

  19. 21 CFR 876.1400 - Stomach pH electrode.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Stomach pH electrode. 876.1400 Section 876.1400...) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Diagnostic Devices § 876.1400 Stomach pH electrode. (a) Identification. A stomach pH electrode is a device used to measure intragastric and intraesophageal pH (hydrogen...

  20. Transcriptomic Resilience of the Montipora digitata Holobiont to Low pH

    Directory of Open Access Journals (Sweden)

    Raúl A. González-Pech

    2017-12-01

    Full Text Available Ocean acidification is considered as one of the major threats for coral reefs at a global scale. Marine calcifying organisms, including stony corals, are expected to be the most affected by the predicted decrease of the surface water pH at the end of the century. The severity of the impacts on coral reefs remains as a matter of controversy. Although previous studies have explored the physiological response of stony corals to changes in pH, the response of the holobiont (i.e., the coral itself plus its symbionts remains largely unexplored. In the present study, we assessed the changes in overall gene expression of the coral Montipora digitata and its microalgal symbionts after a short (3 days and a longer (42 days exposure to low pH (7.6. The short-term exposure to low pH caused small differences in the expression level of the host, impacting mostly genes associated with stress response in other scleractinians. Longer exposure to low pH resulted in no significant changes in gene expression of treated vs. control coral hosts. Gene expression in the eukaryotic symbionts remained unaltered at both exposure times. Our findings suggest resilience, in terms of gene expression, of the M. digitata holobiont to pH decrease, as well as capability to acclimatize to extended periods of exposure to low pH.

  1. Low pH Cements

    International Nuclear Information System (INIS)

    Savage, David; Benbow, Steven

    2007-05-01

    The development of low-pH cements for use in geological repositories for radioactive waste stems from concerns over the potential for deleterious effects upon the host rock and other EBS materials (notably bentonite) under the hyperalkaline conditions (pH > 12) of cement pore fluids. Low pH cement (also known as low heat cement) was developed by the cement industry for use where large masses of cement (e.g. dams) could cause problems regarding heat generated during curing. In low pH cements, the amount of cement is reduced by substitution of materials such as fly ash, blast furnace slag, silica fume, and/or non-pozzolanic silica flour. SKB and Posiva have ruled out the use of blast furnace slag and fly-ash and are focusing on silica fume as a blending agent. Currently, no preferred composition has been identified by these agencies. SKB and Posiva have defined a pH limit ≤ 11 for cement grout leachates. To attain this pH, blending agents must comprise at least 50 wt % of dry materials. Because low pH cement has little, or no free portlandite, the cement consists predominantly of calcium silicate hydrate (CSH) gel with a Ca/Si ratio ≤ 0.8. Although there are potential implications for the performance of the spent fuel and cladding due to the presence of hyperalkaline fluids from cement, the principal focus for safety assessment lies with the behaviour of bentonite. There are a number of potential constraints on the interaction of hyperalkaline cement pore fluids with bentonite, including mass balance, thermodynamic issues, mass transport, and kinetics, but none of these is likely to be limiting if conventional OPC cements are employed in repository construction. Nevertheless: Low-pH cements may supply approximately 50 % less hydroxyl ions than conventional OPC for a given volume of cement, but mass balance constraints are complicated by the uncertainty concerning the type of secondary minerals produced during cement-bentonite interaction. The change of aqueous

  2. Low pH Cements

    Energy Technology Data Exchange (ETDEWEB)

    Savage, David; Benbow, Steven [Quintessa Ltd., Henley-on-Thames (United Kingdom)

    2007-05-15

    The development of low-pH cements for use in geological repositories for radioactive waste stems from concerns over the potential for deleterious effects upon the host rock and other EBS materials (notably bentonite) under the hyperalkaline conditions (pH > 12) of cement pore fluids. Low pH cement (also known as low heat cement) was developed by the cement industry for use where large masses of cement (e.g. dams) could cause problems regarding heat generated during curing. In low pH cements, the amount of cement is reduced by substitution of materials such as fly ash, blast furnace slag, silica fume, and/or non-pozzolanic silica flour. SKB and Posiva have ruled out the use of blast furnace slag and fly-ash and are focusing on silica fume as a blending agent. Currently, no preferred composition has been identified by these agencies. SKB and Posiva have defined a pH limit {<=} 11 for cement grout leachates. To attain this pH, blending agents must comprise at least 50 wt % of dry materials. Because low pH cement has little, or no free portlandite, the cement consists predominantly of calcium silicate hydrate (CSH) gel with a Ca/Si ratio {<=} 0.8. Although there are potential implications for the performance of the spent fuel and cladding due to the pres