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.

Extraction of indirectly captured information for use in a comparison of offline pH measurement technologies.

Science.gov (United States)

Ritchie, Elspeth K; Martin, Elaine B; Racher, Andy; Jaques, Colin

2017-06-10

Understanding the causes of discrepancies in pH readings of a sample can allow more robust pH control strategies to be implemented. It was found that 59.4% of differences between two offline pH measurement technologies for an historical dataset lay outside an expected instrument error range of ±0.02pH. A new variable, Osmo Res , was created using multiple linear regression (MLR) to extract information indirectly captured in the recorded measurements for osmolality. Principal component analysis and time series analysis were used to validate the expansion of the historical dataset with the new variable Osmo Res . MLR was used to identify variables strongly correlated (p<0.05) with differences in pH readings by the two offline pH measurement technologies. These included concentrations of specific chemicals (e.g. glucose) and Osmo Res, indicating culture medium and bolus feed additions as possible causes of discrepancies between the offline pH measurement technologies. Temperature was also identified as statistically significant. It is suggested that this was a result of differences in pH-temperature compensations employed by the pH measurement technologies. In summary, a method for extracting indirectly captured information has been demonstrated, and it has been shown that competing pH measurement technologies were not necessarily interchangeable at the desired level of control (±0.02pH). Copyright © 2017 Elsevier B.V. All rights reserved.

In vivo measurement of cytosolic and mitochondrial pH using a pH-sensitive GFP derivative in Saccharomyces cerevisiae reveals a relation between intracellular pH and growth

NARCIS (Netherlands)

Orij, R.; Postmus, J.; ter Beek, A.; Brul, S.; Smits, G.J.

2009-01-01

The specific pH values of cellular compartments affect virtually all biochemical processes, including enzyme activity, protein folding and redox state. Accurate, sensitive and compartment-specific measurements of intracellular pH (pHi) dynamics in living cells are therefore crucial to the

Meta-Cresol Purple Reference Material® (RM) for Seawater pH Measurements

Science.gov (United States)

Easley, R. A.; Waters, J. F.; Place, B. J.; Pratt, K. W.

2016-02-01

The pH of seawater is a fundamental quantity that governs the carbon dioxide - carbonate system in the world's oceans. High quality pH measurements for long-term monitoring, shipboard studies, and shorter-term biological studies (mesocosm and field experiments) can be ensured through a reference material (RM) that is compatible with existing procedures and which is traceable to primary pH measurement metrology. High-precision spectrophotometric measurements of seawater pH using an indicator dye such as meta-cresol purple (mCP) are well established. However, traceability of these measurements to the International System of Units (SI) additionally requires characterizing the spectrophotometric pH response of the dye in multiple artificial seawater buffers that themselves are benchmarked via primary pH (Harned cell) measurements at a range of pH, salinity, and temperature. NIST is currently developing such a mCP pH RM using this approach. This material will also incorporate new procedures developed at NIST for assessing the purity and homogeneity of the mCP reagent itself. The resulting mCP will provide long-term (years) stability and ease of shipment compared to artificial seawater pH buffers. These efforts will provide the oceanographic user community with a NIST issued mCP (RM), characterized as to its molar absorptivity values and acid dissociation constants (pKa), with uncertainties that comply with the Guide to the Expression of Uncertainty in Measurement (GUM).

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.)

Measurement of pH, exudate composition and temperature in wound healing: a systematic review.

Science.gov (United States)

Power, G; Moore, Z; O'Connor, T

2017-07-02

To assess the potential of measurements of pH, exudate composition and temperature in wounds to predict healing outcomes and to identify the methods that are employed to measure them. A systematic review based on the outcomes of a search strategy of quantitative primary research published in the English language was conducted. Inclusion criteria limited studies to those involving in vivo and human participants with an existing or intentionally provoked wound, defined as 'a break in the epithelial integrity of the skin', and excluded in vitro and animal studies. Data synthesis and analysis was performed using structured narrative summaries of each included study arranged by concept, pH, exudate composition and temperature. The Evidence Based Literature (EBL) Critical Appraisal Checklist was implemented to appraise the quality of the included studies. A total of 23 studies, three for pH (mean quality score 54.48%), 12 for exudate composition (mean quality score 46.54%) and eight for temperature (mean quality score 36.66%), were assessed as eligible for inclusion in this review. Findings suggest that reduced pH levels in wounds, from alkaline towards acidic, are associated with improvements in wound condition. Metalloproteinase-9 (MMP-9), matrix metalloproteinase-2 (MMP-2), tissue inhibitor of metalloproteinase (TIMP), neutrophil elastase (NE) and albumin, in descending order, were the most frequently measured analytes in wounds. MMP-9 emerged as the analyte which offers the most potential as a biomarker of wound healing, with elevated levels observed in acute or non-healing wounds and decreasing levels in wounds progressing in healing. Combined measures of different exudate components, such as MMP/TIMP ratios, also appeared to offer substantial potential to indicate wound healing. Finally, temperature measurements are highest in non-healing, worsening or acute wounds and decrease as wounds progress towards healing. Methods used to measure pH, exudate composition and

pH measurement of tubular vacuoles of an arbuscular mycorrhizal fungus, Gigaspora margarita.

Science.gov (United States)

Funamoto, Rintaro; Saito, Katsuharu; Oyaizu, Hiroshi; Aono, Toshihiro; Saito, Masanori

2015-01-01

Arbuscular mycorrhizal fungi play an important role in phosphate supply to the host plants. The fungal hyphae contain tubular vacuoles where phosphate compounds such as polyphosphate are accumulated. Despite their importance for the phosphate storage, little is known about the physiological properties of the tubular vacuoles in arbuscular mycorrhizal fungi. As an indicator of the physiological state in vacuoles, we measured pH of tubular vacuoles in living hyphae of arbuscular mycorrhizal fungus Gigaspora margarita using ratio image analysis with pH-dependent fluorescent probe, 6-carboxyfluorescein. Fluorescent images of the fine tubular vacuoles were obtained using a laser scanning confocal microscope, which enabled calculation of vacuolar pH with high spatial resolution. The tubular vacuoles showed mean pH of 5.6 and a pH range of 5.1-6.3. These results suggest that the tubular vacuoles of arbuscular mycorrhizal fungi have a mildly acidic pH just like vacuoles of other fungal species including yeast and ectomycorrhizal fungi.

Measuring interstitial pH and pO2 in mouse tumors.

Science.gov (United States)

Jain, Rakesh K; Munn, Lance L; Fukumura, Dai

2013-07-01

This protocol outlines methods to measure two extravascular parameters, interstitial pH and partial pressure of oxygen (pO2), in mouse tumors. The method for measuring interstitial pH uses fluorescence ratio imaging microscopy (FRIM) of the pH-sensitive fluorescent dye 2',7'-bis-(2-carboxyethyl)-5,6-carboxyfluorescein (BCECF). The method for measuring interstitial pO2 is based on the oxygen-dependent quenching of the phosphorescence of albumin-bound palladium meso-tetra(4-carboxyphenyl)porphyrin, and can be used to measure microvascular as well as interstitial pO2. In addition, the two methods can be used sequentially to measure both pH and pO2 in the same tissues.

A method for measuring pH at high temperatures is presented

International Nuclear Information System (INIS)

Chaudon, Luc.

1979-01-01

Two hydrogen electrodes are used and set up in a PTFE cell comprising two chambers connected through a saturated potassium chloride solution bridge. This cell is put in an autoclave containing hydrogen. The potential difference of the following cell is measured: H 2 , Pt, R solution - KCl saturated solution at 25 0 C - X solution, Pt, H 2 - The pH of the reference solution R is known up to 300 0 C and the X solution must have its pH to be determined. The precision of the measures at 300 0 C is estimated about +-0,1 pH unit. The dissociation constant of water is calculated from pH variations of alcaline solutions up to 300 0 C. The method has helped to measure the pH at 300 0 C of some boric acid solutions, with or without lithium hydroxide additions, in the following concentration range: B: 250 to 1500 ppm and Li: 0 to 3 ppm. Some concentrations are in fact those chosen for the primary circuits of pressurized water reactors. The pH of ammoniacal solutions is measured too and helped to determine the variations of the dissociation constant of ammonia with temperature [fr

Live-cell Microscopy and Fluorescence-based Measurement of Luminal pH in Intracellular Organelles

Directory of Open Access Journals (Sweden)

Li Ma

2017-08-01

Full Text Available Luminal pH is an important functional feature of intracellular organelles. Acidification of the lumen of organelles such as endosomes, lysosomes, and the Golgi apparatus plays a critical role in fundamental cellular processes. As such, measurement of the luminal pH of these organelles has relevance to both basic research and translational research. At the same time, accurate measurement of intraorganellar pH in living cells can be challenging and may be a limiting hurdle for research in some areas. Here, we describe three powerful methods to measure rigorously the luminal pH of different intracellular organelles, focusing on endosomes, lysosomes, and the Golgi apparatus. The described methods are based on live imaging of pH-sensitive fluorescent probes and include: (1 A protocol based on quantitative, ratiometric measurement of endocytosis of pH-sensitive and pH-insensitive fluorescent conjugates of transferrin; (2 A protocol for the use of proteins tagged with a ratiometric variant of the pH-sensitive intrinsically fluorescent protein pHluorin; and (3 A protocol using the fluorescent dye LysoSensor™. We describe necessary reagents, key procedures, and methods and equipment for data acquisition and analysis. Examples of implementation of the protocols are provided for cultured cells derived from a cancer cell line and for primary cultures of mouse hippocampal neurons. In addition, we present strengths and weaknesses of the different described intraorganellar pH measurement methods. These protocols are likely to be of benefit to many researchers, from basic scientists to those conducting translational research with a focus on diseases in patient-derived cells.

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.

Apoplastic pH in corn root gravitropism: a laser scanning confocal microscopy measurement

International Nuclear Information System (INIS)

Taylor, D.P.; Slattery, J.; Leopold, A.C.

1996-01-01

The ability to measure the pH of the apoplast in situ is of special interest as a test of the cell wall acidification theory. Optical sectioning of living seedlings of corn roots using the laser scanning confocal microscope (LSCM) permits us to make pH measurements in living tissue. The pH of the apoplast of corn roots was measured by this method after infiltration with CI-NERF, a pH-sensitive dye, along with Texas Red Dextran 3000, a pH-insensitive dye, as an internal standard. In the elongation zone of corn roots, the mean apoplastic pH was 4.9. Upon gravitropic stimulation, the pH on the convex side of actively bending roots was 4.5. The lowering of the apoplastic pH by 0.4 units appears to be sufficient to account for the increased growth on that side. This technique provides site-specific evidence for the acid growth theory of cell elongation. The LSCM permits measurements of the pH of living tissues, and has a sensitivity of approximately 0.2 pH units. (author)

Development of a colorimetric microfluidic pH sensor for autonomous seawater measurements.

Science.gov (United States)

Rérolle, Victoire M C; Floquet, Cedric F A; Harris, Andy J K; Mowlem, Matt C; Bellerby, Richard R G J; Achterberg, Eric P

2013-07-05

High quality carbonate chemistry measurements are required in order to fully understand the dynamics of the oceanic carbonate system. Seawater pH data with good spatial and temporal coverage are particularly critical to apprehend ocean acidification phenomena and their consequences. There is a growing need for autonomous in situ instruments that measure pH on remote platforms. Our aim is to develop an accurate and precise autonomous in situ pH sensor for long term deployment on remote platforms. The widely used spectrophotometric pH technique is capable of the required high-quality measurements. We report a key step towards the miniaturization of a colorimetric pH sensor with the successful implementation of a simple microfluidic design with low reagent consumption. The system is particularly adapted to shipboard deployment: high quality data was obtained over a period of more than a month during a shipboard deployment in northwest European shelf waters, and less than 30 mL of indicator was consumed. The system featured a short term precision of 0.001 pH (n=20) and an accuracy within the range of a certified Tris buffer (0.004 pH). The quality of the pH system measurements have been checked using various approaches: measurements of certified Tris buffer, measurement of certified seawater for DIC and TA, comparison of measured pH against calculated pH from pCO2, DIC and TA during the cruise in northwest European shelf waters. All showed that our measurements were of high quality. The measurements were made close to in situ temperature (+0.2°C) in a sampling chamber which had a continuous flow of the ship's underway seawater supply. The optical set up was robust and relatively small due to the use of an USB mini-spectrometer, a custom made polymeric flow cell and an LED light source. The use of a three wavelength LED with detection that integrated power across the whole of each LED output spectrum indicated that low wavelength resolution detectors can be used

CMOS COLOUR SENSOR BASED pH MEASUREMENT FOR WATER QUALITY ANALYSIS

OpenAIRE

Sanjay Kumar; Arvind Singh

2016-01-01

A Real-Time pH measurement system using a novel design Programmable CMOS optical Colour light to frequency converter TCS230 is presented. The system uses Bogen’s universal indicator solution combined with a white light source and the Programmable CMOS colour sensor TCS230 to measure pH as a function of colour change in a sample. Bogen’s universal indicator solution causes a colour change in a sample according to the pH of the sample. The output frequency from the colour-sensitive CM...

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

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.

Dual mode antimony electrode for simultaneous measurements of PO2 and pH.

Science.gov (United States)

Sjöberg, F; Nilsson, G

2000-01-01

In biomedical research and clinical medicine there is a demand for potent sensors to measure the components that make up blood gas analyses. Today, as when the electrochemical PO2, PCO2 and pH electrodes were first introduced, these measurements are usually made with the same type of sensor technology. The aims of the present study were, firstly, to find out whether the platinum cathode in the Clark electrode can be replaced by antimony for oxygen measurements (amperometry (A)); secondly, whether, during oxygen measurements, the inherent corrosion potential of the antimony metal can be used for measurement of pH in the same measurement area (potentiometry (P)). An electrode of purified, crystallographically orientated monocrystalline antimony (COMA) connected to a reference electrode (silver-silver chloride) was used for the P measurements. Measurements of A (at -900 mV) and P were made in an aqueous environment regulated for oxygen, pH, and temperature. Reproducible oxygen sensitivities of 0.925 nA/% oxygen (2% CV (coefficient of variation)) (A), 10.7 mV/% (P), and 0.7 mV/% (P) were found in the oxygen range: 0-21%, <5%, and above 5%, respectively. The pH sensitivity was 57 mV/pH unit (P). Oxygen and pH measurements were less accurate at oxygen concentrations close to 0%. Both the oxygen and pH part of the composite electrode signal can be identified by this dual mode technique (A and P). The sensor seems to be promising as it provides measurements of two separate variables (oxygen and pH) and also has the desirable characteristics of a solid state sensor.

Soil pH Errors Propagation from Measurements to Spatial Predictions - Cost Benefit Analysis and Risk Assessment Implications for Practitioners and Modelers

Science.gov (United States)

Owens, P. R.; Libohova, Z.; Seybold, C. A.; Wills, S. A.; Peaslee, S.; Beaudette, D.; Lindbo, D. L.

2017-12-01

The measurement errors and spatial prediction uncertainties of soil properties in the modeling community are usually assessed against measured values when available. However, of equal importance is the assessment of errors and uncertainty impacts on cost benefit analysis and risk assessments. Soil pH was selected as one of the most commonly measured soil properties used for liming recommendations. The objective of this study was to assess the error size from different sources and their implications with respect to management decisions. Error sources include measurement methods, laboratory sources, pedotransfer functions, database transections, spatial aggregations, etc. Several databases of measured and predicted soil pH were used for this study including the United States National Cooperative Soil Survey Characterization Database (NCSS-SCDB), the US Soil Survey Geographic (SSURGO) Database. The distribution of errors among different sources from measurement methods to spatial aggregation showed a wide range of values. The greatest RMSE of 0.79 pH units was from spatial aggregation (SSURGO vs Kriging), while the measurement methods had the lowest RMSE of 0.06 pH units. Assuming the order of data acquisition based on the transaction distance i.e. from measurement method to spatial aggregation the RMSE increased from 0.06 to 0.8 pH units suggesting an "error propagation". This has major implications for practitioners and modeling community. Most soil liming rate recommendations are based on 0.1 pH unit increments, while the desired soil pH level increments are based on 0.4 to 0.5 pH units. Thus, even when the measured and desired target soil pH are the same most guidelines recommend 1 ton ha-1 lime, which translates in 111 ha-1 that the farmer has to factor in the cost-benefit analysis. However, this analysis need to be based on uncertainty predictions (0.5-1.0 pH units) rather than measurement errors (0.1 pH units) which would translate in 555-1,111 investment that

Polymeric pH nanosensor with extended measurement range bearing octaarginine as cell penetrating peptide

DEFF Research Database (Denmark)

Ke, Peng; Sun, Honghao; Liu, Mingxing

2016-01-01

A synthetic peptide octaarginine which mimics human immunodeficiency virus-1, Tat protein is used as cell penetrating moiety for new pH nanosensors which demonstrate enhanced cellular uptake and expanded measurement range from pH 3.9 to pH 7.3 by simultaneously incorporating two complemental pH-s......H-sensitive fluorophores in a same nanoparticle. The authors believe that this triple fluorescent pH sensor provides a new tool to pH measurements that can have application in cellular uptake mechanism study and new nanomedicine design.......A synthetic peptide octaarginine which mimics human immunodeficiency virus-1, Tat protein is used as cell penetrating moiety for new pH nanosensors which demonstrate enhanced cellular uptake and expanded measurement range from pH 3.9 to pH 7.3 by simultaneously incorporating two complemental p...

FLEXIBLE PH SENSOR WITH POLYANILINE LAYER BASED ON IMPEDANCE MEASUREMENT

OpenAIRE

Chuang, Cheng-Hsin; Wu, Hsun-Pei; Chen, Cheng-Ho; Wu, Peng-Rong

2012-01-01

A flexible sensor with conducting polyaniline layer for detecting pH value based on the impedance measurement is fabricated and demonstrated in this study. The pH sensor consists of an interdigital electrode array on a flexible printed circuit and a thin-film polyaniline as the sensing layer. As the conductivity of polyaniline depends on the redox state, the impedance change of the polyaniline after it has reacted with different pH value solutions works as the sensing mechanism. In order to o...

Measuring pH variability using an experimental sensor on an underwater glider

Science.gov (United States)

Hemming, Michael P.; Kaiser, Jan; Heywood, Karen J.; Bakker, Dorothee C. E.; Boutin, Jacqueline; Shitashima, Kiminori; Lee, Gareth; Legge, Oliver; Onken, Reiner

2017-05-01

Autonomous underwater gliders offer the capability of measuring oceanic parameters continuously at high resolution in both vertical and horizontal planes, with timescales that can extend to many months. An experimental ion-sensitive field-effect transistor (ISFET) sensor measuring pH on the total scale was attached to a glider during the REP14-MED experiment in June 2014 in the Sardinian Sea in the northwestern Mediterranean. During the deployment, pH was sampled at depths of up to 1000 m along an 80 km transect over a period of 12 days. Water samples were collected from a nearby ship and analysed for dissolved inorganic carbon concentration and total alkalinity to derive the pH for validating the ISFET sensor measurements. The vertical resolution of the pH sensor was good (1 to 2 m), but stability was poor and the sensor drifted in a non-monotonous fashion. In order to remove the sensor drift, a depth-constant time-varying offset was applied throughout the water column for each dive, reducing the spread of the data by approximately two-thirds. Furthermore, the ISFET sensor required temperature- and pressure-based corrections, which were achieved using linear regression. Correcting for this decreased the apparent sensor pH variability by a further 13 to 31 %. Sunlight caused an apparent sensor pH decrease of up to 0.1 in surface waters around local noon, highlighting the importance of shielding the sensor from light in future deployments. The corrected pH from the ISFET sensor is presented along with potential temperature, salinity, potential density anomalies (σθ), and dissolved oxygen concentrations (c(O2)) measured by the glider, providing insights into the physical and biogeochemical variability in the Sardinian Sea. The pH maxima were identified close to the depth of the summer chlorophyll maximum, where high c(O2) values were also found. Longitudinal pH variations at depth (σθ > 28. 8 kg m-3) highlighted the variability of water masses in the Sardinian

Measuring pH variability using an experimental sensor on an underwater glider

Directory of Open Access Journals (Sweden)

M. P. Hemming

2017-05-01

Full Text Available Autonomous underwater gliders offer the capability of measuring oceanic parameters continuously at high resolution in both vertical and horizontal planes, with timescales that can extend to many months. An experimental ion-sensitive field-effect transistor (ISFET sensor measuring pH on the total scale was attached to a glider during the REP14-MED experiment in June 2014 in the Sardinian Sea in the northwestern Mediterranean. During the deployment, pH was sampled at depths of up to 1000 m along an 80 km transect over a period of 12 days. Water samples were collected from a nearby ship and analysed for dissolved inorganic carbon concentration and total alkalinity to derive the pH for validating the ISFET sensor measurements. The vertical resolution of the pH sensor was good (1 to 2 m, but stability was poor and the sensor drifted in a non-monotonous fashion. In order to remove the sensor drift, a depth-constant time-varying offset was applied throughout the water column for each dive, reducing the spread of the data by approximately two-thirds. Furthermore, the ISFET sensor required temperature- and pressure-based corrections, which were achieved using linear regression. Correcting for this decreased the apparent sensor pH variability by a further 13 to 31 %. Sunlight caused an apparent sensor pH decrease of up to 0.1 in surface waters around local noon, highlighting the importance of shielding the sensor from light in future deployments. The corrected pH from the ISFET sensor is presented along with potential temperature, salinity, potential density anomalies (σθ, and dissolved oxygen concentrations (c(O2 measured by the glider, providing insights into the physical and biogeochemical variability in the Sardinian Sea. The pH maxima were identified close to the depth of the summer chlorophyll maximum, where high c(O2 values were also found. Longitudinal pH variations at depth (σθ > 28. 8 kg m−3 highlighted the variability of

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

Optimization of the automated colorimetric measurement system for pH of liquid

Directory of Open Access Journals (Sweden)

Katin Oleg

2017-01-01

Full Text Available This article considers the issue of automatic control of the acidity of the aquatic environment, which is relevant in such branches of agriculture as hydroponics and aeroponics. A method for measuring the pH of a liquid using a potentiometric method is considered. This method allows to obtain the most accurate pH values, but has some drawbacks. In particular, the article analyzes the advantages of this method over the use of a universal indicator paper and a color sensor for pH determination, describes the components, the conditions of their operation and storage, describes the basic principles of the measuring system operation. A method for converting a signal received at a pH electrode into a microcontroller suitable for processing is also contemplated. The main goal of the development and application of the measuring system described in the article is to achieve a high degree of autonomy and automation of aeroponic and hydroponic greenhouse complexes.

Cross-linked self-assembled micelle based nanosensor for intracellular pH measurements

DEFF Research Database (Denmark)

Ek, Pramod Kumar; Søndergaard, Rikke Vicki; Windschiegl, Barbara

2014-01-01

A micelle based nanosensor was synthesized and investigated as a ratiometric pH sensor for use in measurements in living cells by fluorescent microscopy. The nanosensor synthesis was based on self-assembly of an amphiphilic triblock copolymer, which was chemically cross-linked after micelle......-linked by an amidation reaction using 3,6,9-trioxaundecandioic acid cross-linker. The cross-linked micelle was functionalized with two pH sensitive fluorophores and one reference fluorophore, which resulted in a highly uniform ratiometric pH nanosensor with a diameter of 29 nm. The use of two sensor fluorophores...... provided a sensor with a very broad measurement range that seems to be influenced by the chemical design of the sensor. Cell experiments show that the sensor is capable of monitoring the pH distributions in HeLa cells....

Fetal short time variation during labor: a non-invasive alternative to fetal scalp pH measurements?

Science.gov (United States)

Schiermeier, Sven; Reinhard, Joscha; Hatzmann, Hendrike; Zimmermann, Ralf C; Westhof, Gregor

2009-01-01

To determine whether short time variation (STV) of fetal heart beat correlates with scalp pH measurements during labor. From 1279 deliveries, 197 women had at least one fetal scalp pH measurement. Using the CTG-Player, STVs were calculated from the electronically saved cardiotocography (CTG) traces and related to the fetal scalp pH measurements. There was no correlation between STV and fetal scalp pH measurements (r=-0.0592). Fetal STV is an important parameter with high sensitivity for antenatal fetal acidosis. This study shows that STV calculations do not correlate with fetal scalp pH measurements during labor, hence are not helpful in identifying fetal acidosis.

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

Measurements of spectral responses for developing fiber-optic pH sensor

Science.gov (United States)

Yoo, Wook Jae; Heo, Ji Yeon; Jang, Kyoung Won; Seo, Jeong Ki; Moon, Jin Soo; Park, Jang-Yeon; Park, Byung Gi; Cho, Seunghyun; Lee, Bongsoo

2011-01-01

In this study, we have fabricated a fiber-optic pH sensor, which is composed of a light source, a pH-sensing probe, plastic optical fibers and a spectrometer, for determining the degree of infection by Helicobacter pylori in the stomach. As pH indicators, phenol red and m-cresol purple are used, and pH liquid solutions are prepared by mixing phenol red or m-cresol purple solutions and various kinds of pH buffer solutions. The light emitted by a light source is guided by plastic optical fibers to the pH liquid solution, and the optical characteristic of a reflected light is changed according to the color variations of the pH indicator in the pH-sensing probe. Therefore, we have measured the intensities and wavelength shifts of the reflected lights, which change according to the color variations of indicators at different pH values, by using a spectrometer for spectral analysis. Also, the relationships between the pH values of liquid solutions and the optical properties of the modulated lights are obtained on the basis of the changes of the colors of indicators.

Fetal short time variation during labor: a non-invasive alternative to fetal scalp pH measurements?

OpenAIRE

Schiermeier, Sven; Reinhard, Joscha; Hatzmann, Hendrike; Zimmermann, Ralf C.; Westhof, Gregor

2009-01-01

Objective: To determine whether short time variation (STV) of fetal heart beat correlates with scalp pH measurements during labor. Patients and methods: From 1279 deliveries, 197 women had at least one fetal scalp pH measurement. Using the CTG-Player®, STVs were calculated from the electronically saved cardiotocography (CTG) traces and related to the fetal scalp pH measurements. Results: There was no correlation between STV and fetal scalp pH measurements (r=−0.0592). Conclusions: Fetal ST...

Laser-induced breakdown spectroscopy: Extending its application to soil pH measurements

Energy Technology Data Exchange (ETDEWEB)

Ferreira, Edilene Cristina, E-mail: edilene@iq.unesp.br [São Paulo State University – UNESP, Analytical Chemistry Department, Rua Prof. Francisco Degni 55, CEP 14800-060, Araraquara, SP (Brazil); Gomes Neto, José A. [São Paulo State University – UNESP, Analytical Chemistry Department, Rua Prof. Francisco Degni 55, CEP 14800-060, Araraquara, SP (Brazil); Milori, Débora M.B.P.; Ferreira, Ednaldo José [Embrapa Agricultural Instrumentation, Rua XV de Novembro 1452, CEP 13560-970, São Carlos, SP (Brazil); Anzano, Jesús Manuel [Laser Laboratory & Environment, Faculty of Sciences, University of Zaragoza, C/. Pedro Cerbuna 12, 50009, Zaragoza (Spain)

2015-08-01

Acid–base equilibria are involved in almost all the processes that occur in soil. The bioavailability of nutrients for plants, for instance, depends on the solubilization of mineral nutrients in the soil solution, which is a pH-dependent process. The determination of pH in soil solutions is usually carried out by potentiometry using a glass membrane electrode, after extracting some of the soil components with water or CaCl{sub 2} solution. The present work describes a simple method for determining the pH of soil, using laser-induced breakdown spectroscopy (LIBS). Sixty samples presenting different textural composition and pH (previously determined by potentiometry) were employed. The samples were divided into a calibration set with fifty samples and a validation set with ten samples. LIBS spectra were recorded for each pelleted sample using laser pulse energy of 115 mJ. The intensities of thirty-two emission lines for Al, Ca, H, and O were used to fit a partial least squares (PLS) model. The model was validated by prediction of the pH of the validation set samples, which showed good agreement with the reference values. The prediction mean absolute error was 0.3 pH units and the root mean square error of the prediction was 0.4. These results highlight the potential of LIBS for use in other applications beyond elemental composition determinations. For soil analysis, the proposed method offers the possibility of determining pH, in addition to nutrients and contaminants, using a single LIBS measurement. - Highlights: • Physical, chemical, and biological properties of soil are influenced by pH. • The pH of mineral soils is normally determined in slurries of water and soil sample by potentiometric measurements. • The association of LIBS elemental emissions with multivariate strategies of analysis has become LIBS a powerful technique. • LIBS was unprecedentedly applied for direct pH determination in different kinds of soil sample. • The clean and fast proposed

Measurement of pH micro-heterogeneity in natural cheese matrices by fluorescence lifetime imaging

Directory of Open Access Journals (Sweden)

Zuzana eBurdikova

2015-03-01

Full Text Available Cheese, a product of microbial fermentation may be defined as a protein matrix entrapping fat, moisture, minerals and solutes as well as dispersed bacterial colonies. The growth and physiology of bacterial cells in these colonies may be influenced by the microenvironment around the colony, or alternatively the cells within the colony may modify the microenvironment (e.g. pH, redox potential due to their metabolic activity. While cheese pH may be measured at macro level there remains a significant knowledge gap relating to the degree of micro-heterogeneity of pH within the cheese matrix and its relationship with microbial, enzymatic and physiochemical parameters and ultimately with cheese quality, consistency and ripening patterns. The pH of cheese samples was monitored both at macroscopic scale and at microscopic scale, using a non-destructive microscopic technique employing C-SNARF-4 and Oregon Green 488 fluorescent probes. The objectives of this work were to evaluate the suitability of these dyes for microscale pH measurements in natural cheese matrices and to enhance the sensitivity and extend the useful pH range of these probes using fluorescence lifetime imaging (FLIM. In particular, fluorescence lifetime of Oregon Green 488 proved to be sensitive probe to map pH micro heterogeneity within cheese matrices. Good agreement was observed between macroscopic scale pH measurement by FLIM and by traditional pH methods, but in addition considerable localized microheterogeneity in pH was evident within the curd matrix with pH range between 4.0 and 5.5. This technique provides significant potential to further investigate the relationship between cheese matrix physico-chemistry and bacterial metabolism during cheese manufacture and ripening.

Measurement of pH micro-heterogeneity in natural cheese matrices by fluorescence lifetime imaging.

Science.gov (United States)

Burdikova, Zuzana; Svindrych, Zdenek; Pala, Jan; Hickey, Cian D; Wilkinson, Martin G; Panek, Jiri; Auty, Mark A E; Periasamy, Ammasi; Sheehan, Jeremiah J

2015-01-01

Cheese, a product of microbial fermentation may be defined as a protein matrix entrapping fat, moisture, minerals and solutes as well as dispersed bacterial colonies. The growth and physiology of bacterial cells in these colonies may be influenced by the microenvironment around the colony, or alternatively the cells within the colony may modify the microenvironment (e.g., pH, redox potential) due to their metabolic activity. While cheese pH may be measured at macro level there remains a significant knowledge gap relating to the degree of micro-heterogeneity of pH within the cheese matrix and its relationship with microbial, enzymatic and physiochemical parameters and ultimately with cheese quality, consistency and ripening patterns. The pH of cheese samples was monitored both at macroscopic scale and at microscopic scale, using a non-destructive microscopic technique employing C-SNARF-4 and Oregon Green 488 fluorescent probes. The objectives of this work were to evaluate the suitability of these dyes for microscale pH measurements in natural cheese matrices and to enhance the sensitivity and extend the useful pH range of these probes using fluorescence lifetime imaging (FLIM). In particular, fluorescence lifetime of Oregon Green 488 proved to be sensitive probe to map pH micro heterogeneity within cheese matrices. Good agreement was observed between macroscopic scale pH measurement by FLIM and by traditional pH methods, but in addition considerable localized microheterogeneity in pH was evident within the curd matrix with pH range between 4.0 and 5.5. This technique provides significant potential to further investigate the relationship between cheese matrix physico-chemistry and bacterial metabolism during cheese manufacture and ripening.

A tunable ratiometric pH sensor based on carbon nanodots for the quantitative measurement of the intracellular pH of whole cells.

Science.gov (United States)

Shi, Wen; Li, Xiaohua; Ma, Huimin

2012-06-25

The whole picture: Carbon nanodots labeled with two fluorescent dyes have been developed as a tunable ratiometric pH sensor to measure intracellular pH. The nanosensor shows good biocompatibility and cellular dispersibility. Quantitative determinations on intact HeLa cells and pH fluctuations associated with oxidative stress were performed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A hydrogel based nanosensor with an unprecedented broad sensitivity range for pH measurements in cellular compartments

DEFF Research Database (Denmark)

Zhang, M.; Søndergaard, Rikke Vicki; Ek, Pramod Kumar

2015-01-01

Optical pH nanosensors have been applied for monitoring intracellular pH in real-time for about two decades. However, the pH sensitivity range of most nanosensors is too narrow, and measurements that are on the borderline of this range may not be correct. Furthermore, ratiometric measurements...... of acidic intracellular pH (pH sensor, a fluorophore based nanosensor, with an unprecedented broad measurement range from pH 1.4 to 7.0. In this nanosensor, three p......H-sensitive fluorophores (difluoro-Oregon Green, Oregon Green 488, and fluorescein) and one pH-insensitive fluorophore (Alexa 568) were covalently incorporated into a nanoparticle hydrogel matrix. With this broad range quadruple-labelled nanosensor all physiological relevant pH levels in living cells can be measured...

Assessment of the suitability of Durafet-based sensors for pH measurement in dynamic estuarine environments

Science.gov (United States)

Gonski, Stephen F.; Cai, Wei-Jun; Ullman, William J.; Joesoef, Andrew; Main, Christopher R.; Pettay, D. Tye; Martz, Todd R.

2018-01-01

The suitability of the Honeywell Durafet to the measurement of pH in productive, high-fouling, and highly-turbid estuarine environments was investigated at the confluence of the Murderkill Estuary and Delaware Bay (Delaware, USA). Three different flow configurations of the SeapHOx sensor equipped with a Honeywell Durafet and its integrated internal (Ag/AgCl reference electrode containing a 4.5 M KCl gel liquid junction) and external (solid-state chloride ion selective electrode, Cl-ISE) reference electrodes were deployed for four periods between April 2015 and September 2016. In this environment, the Honeywell Durafet proved capable of making high-resolution and high-frequency pH measurements on the total scale between pH 6.8 and 8.4. Natural pH fluctuations of >1 pH unit were routinely captured over a range of timescales. The sensor pH collected between May and August 2016 using the most refined SeapHOx configuration exhibited good agreement with multiple sets of independently measured reference pH values. When deployed in conjunction with rigorous discrete sampling and calibration schemes, the sensor pH had a root-mean squared error ranging between 0.011 and 0.036 pH units across a wide range of salinity relative to both pHT calculated from measured dissolved inorganic carbon and total alkalinity and pHNBS measured with a glass electrode corrected to pHT at in situ conditions. The present work demonstrates the viability of the Honeywell Durafet to the measurement of pH to within the weather-level precision defined by the Global Ocean Acidification Observing Network (GOA-ON, ≤ 0.02 pH units) as a part of future estuarine CO2 chemistry studies undertaken in dynamic environments.

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.

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.

Titration and Spectroscopic Measurements of Poultry Litter pH Buffering Capacity.

Science.gov (United States)

Cassity-Duffey, Kate; Cabrera, Miguel; Mowrer, Jake; Kissel, David

2015-07-01

The pH value of poultry litter is affected by nitrification, mineralization, and the addition of acidifying chemicals, all acting on the poultry litter pH buffering capacity (pHBC). Increased understanding of poultry litter pHBC will aid in modeling NH volatilization from surface-applied poultry litter as well as estimating rates of alum applications. Our objectives were to (i) determine the pHBC of a wide range of poultry litters; (ii) assess the accuracy of near-infrared reflectance spectroscopy (NIRS) for determining poultry litter pHBC; and (iii) demonstrate the use of poultry litter pHBC to increase the accuracy of alum additions. Litter pHBC was determined by titration and calculated from linear and sigmoidal curves. For the 37 litters measured, linear pHBC ranged from 187 to 537 mmol (pH unit) kg dry litter. The linear and sigmoidal curves provided accurate predictions of pHBC, with most > 0.90. Results from NIRS analysis showed that the linear pHBC expressed on an "as is" water content basis had a NIRS coefficient of calibration (developed using a modified partial least squares procedure) of 0.90 for the 37 poultry litters measured. Using the litter pHBC, an empirical model was derived to determine the amount of alum needed to create a target pH. The model performed well in the range of pH 6.5 to 7.5 (RMSE = 0.07) but underpredicted the amount of alum needed to reach pH litter, which prevented its hydrolysis. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

A wireless pH sensor using magnetoelasticity for measurement of body fluid acidity.

Science.gov (United States)

Pang, Pengfei; Gao, Xianjuan; Xiao, Xilin; Yang, Wenyue; Cai, Qingyun; Yao, Shouzhuo

2007-04-01

The determination of body fluid acidity using a wireless magnetoelastic pH-sensitive sensor is described. The sensor was fabricated by casting a layer of pH-sensitive polymer on a magnetoelastic ribbon. In response to an externally applied time-varying magnetic field, the magnetoelastic sensor mechanically vibrates at a characteristic frequency that is inversely dependent upon the mass of the pH polymer film, which varies as the film swells and shrinks in response to pH. As the magnetoelastic sensor is magnetostrictive, the mechanical vibrations of the sensor launch magnetic flux that can be detected remotely using a pickup coil. The sensor can be used for direct measurements of body fluid acidity without a pretreatment of the sample by using a filtration membrane. A reversible and linear response was obtained between pH 5.0 and 8.0 with a measurement resolution of pH 0.1 and a slope of 0.2 kHz pH(-1). Since there are no physical connections between the sensor and the instrument, the sensor can be applied to in vivo and in situ monitoring of the physiological pH and its fluctuations.

Sol gel based fiber optic sensor for blook pH measurement

International Nuclear Information System (INIS)

Grant, S. A.; Glass, R. S.

1996-01-01

This paper describes a fiber-optic pH sensor based upon sol-gel encapsulation of a self-referencing dye, seminaphthorhodamine-1 carboxylate (SNARF-1C). The simple sol-gel fabrication procedure and low coating leachability are ideal for encapsulation and immobilization of dye molecules onto the end of an optical fiber. A miniature bench-top fluorimeter system was developed for use with the optical fiber to obtain pH measurements. Linear and reproducible responses were obtained in human blood in the pH range 6.8 to 8.0, which encompasses the clinically-relevant range. Therefore, this sensor can be considered for in vivo use

Expanding the dynamic measurement range for polymeric nanoparticle pH sensors

DEFF Research Database (Denmark)

Sun, Honghao; Almdal, Kristoffer; Andresen, Thomas Lars

2011-01-01

Conventional optical nanoparticle pH sensors that are designed for ratiometric measurements in cells have been based on utilizing one sensor fluorophore and one reference fluorophore in each nanoparticle, which results in a relatively narrow dynamic measurement range. This results in substantial...

Measurement of peritoneal fluid pH in patients with non-serosal invasive gastric cancer.

Science.gov (United States)

Noh, Seung Moo

2003-02-01

The accurate pH range of peritoneal fluid is clinically valuable for the evaluation of some pathological conditions of the body, however, it is not easy to measure in healthy individuals. The aim of this study was to measure; pH, pCO2, pO2, Na+, K++, Ca++, HCO3-, and O2 saturation of the peritoneal fluid in patients with non-serosal invasive gastric cancer. One hundred and thirty four patients (86 men and 48 women), ranging in age from 24 to 91 years were enrolled in this study. After opening the abdominal wall, the probe of a portable pH meter was placed in the peritoneal fluid in the subhepatic space. In addition, I collected the peritoneal fluid from the subhepatic space to measure, pH, pCO2, pO2, Na+, K++, Ca++, HCO3-, and O2 saturation using an autoanalyzer. The pHs of the peritoneal fluids tested has a mean of 7.73 (range 7.46 - 8.10), and the other parameters were pCO2, 22.81 mmHg; pO2, 136.49 mmHg; Na+, 146.57 mmol/L; K++, 4.80 mmol/L; Ca++, 0.89 mmol/L; HCO3-, 30.54 mmol/L, and O2 saturation, 99.74%. This study describes a practical method of measuring the pH of peritoneal fluid. The result obtained reflects the normal adult peritoneal pH value, which I propose as a reference value.

Microenvironmental pH measurement during sodium naproxenate dissolution in acidic medium by UV/vis imaging

DEFF Research Database (Denmark)

Ostergaard, Jesper; Jensen, Henrik; Larsen, Susan W

2014-01-01

Variable dissolution from sodium salts of drugs containing a carboxylic acid group after passing the acidic environment of the stomach may affect oral bioavailability. The aim of the present proof of concept study was to investigate pH effects in relation to the dissolution of sodium naproxenate...... in 0.01M hydrochloric acid. For this purpose a UV/vis imaging-based approach capable of measuring microenvironmental pH in the vicinity of the solid drug compact as well as monitoring drug dissolution was developed. Using a pH indicating dye real-time spatially resolved measurement of pH was achieved....... Sodium naproxenate, can significantly alter the local pH of the dissolution medium, is eventually neutralized and precipitates as the acidic species naproxen. The developed approach is considered useful for detailed studies of pH dependent dissolution phenomena in dissolution testing....

A miniature integrated multimodal sensor for measuring pH, EC and temperature for precision agriculture.

Science.gov (United States)

Futagawa, Masato; Iwasaki, Taichi; Murata, Hiroaki; Ishida, Makoto; Sawada, Kazuaki

2012-01-01

Making several simultaneous measurements with different kinds of sensors at the same location in a solution is difficult because of crosstalk between the sensors. In addition, because the conditions at different locations in plant beds differ, in situ measurements in agriculture need to be done in small localized areas. We have fabricated a multimodal sensor on a small Si chip in which a pH sensor was integrated with electrical conductivity (EC) and temperature sensors. An ISFET with a Si(3)N(4) membrane was used for the pH sensor. For the EC sensor, the electrical conductivity between platinum electrodes was measured, and the temperature sensor was a p-n junction diode. These are some of the most important measurements required for controlling the conditions in plant beds. The multimodal sensor can be inserted into a plant bed for in situ monitoring. To confirm the absence of crosstalk between the sensors, we made simultaneous measurements of pH, EC, and temperature of a pH buffer solution in a plant bed. When the solution was diluted with hot or cold water, the real time measurements showed changes to the EC and temperature, but no change in pH. We also demonstrated that our sensor was capable of simultaneous in situ measurements in rock wool without being affected by crosstalk.

pH measurements of FET-based (bio)chemical sensors using portable measurement system.

Science.gov (United States)

Voitsekhivska, T; Zorgiebel, F; Suthau, E; Wolter, K-J; Bock, K; Cuniberti, G

2015-01-01

In this study we demonstrate the sensing capabilities of a portable multiplex measurement system for FET-based (bio)chemical sensors with an integrated microfluidic interface. We therefore conducted pH measurements with Silicon Nanoribbon FET-based Sensors using different measurement procedures that are suitable for various applications. We have shown multiplexed measurements in aqueous medium for three different modes that are mutually specialized in fast data acquisition (constant drain current), calibration-less sensing (constant gate voltage) and in providing full information content (sweeping mode). Our system therefore allows surface charge sensing for a wide range of applications and is easily adaptable for multiplexed sensing with novel FET-based (bio)chemical sensors.

Distributed plastic optical fibre measurement of pH using a photon counting OTDR

International Nuclear Information System (INIS)

Saunders, C; Scully, P J

2005-01-01

Distributed measurement of pH was demonstrated at a sensitised region 4m from the distal end of a 20m length of plastic optical fibre. The cladding was removed from the fibre over 150mm and the bare core was exposed to an aqueous solution of methyl red at three values of pH, between 2.89 and 9.70. The optical fibre was interrogated at 648nm using a Luciol photon counting optical time domain reflectometer, and demonstrated that the sensing region was attenuated as a function of pH. The attenuation varied from 16.3 dB at pH 2.89 to 8.6 dB at pH 9.70; this range equated to -1.13 ± 0.04 dB/pH. It is thus possible to determine both the position to ± 12mm and pH to an estimated ± 0.5pH at the sensing region

A Miniature Integrated Multimodal Sensor for Measuring pH, EC and Temperature for Precision Agriculture

Directory of Open Access Journals (Sweden)

Hiroaki Murata

2012-06-01

Full Text Available Making several simultaneous measurements with different kinds of sensors at the same location in a solution is difficult because of crosstalk between the sensors. In addition, because the conditions at different locations in plant beds differ, in situ measurements in agriculture need to be done in small localized areas. We have fabricated a multimodal sensor on a small Si chip in which a pH sensor was integrated with electrical conductivity (EC and temperature sensors. An ISFET with a Si₃N₄ membrane was used for the pH sensor. For the EC sensor, the electrical conductivity between platinum electrodes was measured, and the temperature sensor was a p-n junction diode. These are some of the most important measurements required for controlling the conditions in plant beds. The multimodal sensor can be inserted into a plant bed for in situ monitoring. To confirm the absence of crosstalk between the sensors, we made simultaneous measurements of pH, EC, and temperature of a pH buffer solution in a plant bed. When the solution was diluted with hot or cold water, the real time measurements showed changes to the EC and temperature, but no change in pH. We also demonstrated that our sensor was capable of simultaneous in situ measurements in rock wool without being affected by crosstalk.

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

Ex vivo Porcine Model to Measure pH Dependence of gagCEST in the Inter-Vertebral Disc

Science.gov (United States)

Melkus, Gerd; Grabau, Michelle; Karampinos, Dimitrios C.; Majumdar, Sharmila

2013-01-01

Purpose Studies have linked low pH and loss of glycosaminoglycan (GAG) in the intervertebral discs (IVDs) of patients with discogenic back pain. The purpose of the present study is to determine whether the chemical exchange saturation transfer (CEST) effect of GAG (gagCEST) is pH-dependent and whether it can be used to detect pH changes in IVD specimens. Iopromide, a FDA approved agent for CT/X-Ray, was also evaluated as a pH-sensitive CEST probe to explore the agents’ potential to measure IVD pH. Methods The pH dependency of the CEST effect of chondroitin sulfate (containing GAG) and Iopromide phantoms was investigated at 7 T. Z-spectra from porcine IVD specimens were acquired before and after manipulating the pH with sodium lactate. Iopromide was injected into the specimens and the calibration curve was used to determine the pH status. Results Chondroitin sulfate showed a non-linear dependence of gagCEST effect with pH and gagCEST signal differences were detected in the specimens. The CEST effect of Iopromide resulted in a sigmoidal relation with pH and was used to measure pH. Conclusion gagCEST is sensitive to pH and enables investigation of the IVD pH status. Iopromide CEST is independent of the local GAG concentration and has the potential for measuring pH in the IVD. PMID:23818244

Spectrophotometric high-precision seawater pH determination for use in underway measuring systems

Directory of Open Access Journals (Sweden)

S. Aßmann

2011-10-01

Full Text Available Autonomous sensors are required for a comprehensive documentation of the changes in the marine carbon system and thus to differentiate between its natural variability and anthropogenic impacts. Spectrophotometric determination of pH – a key variable of the seawater carbon system – is particularly suited to achieve precise and drift-free measurements. However, available spectrophotometric instruments are not suitable for integration into automated measurement systems (e.g. FerryBox since they do not meet the major requirements of reliability, stability, robustness and moderate cost. Here we report on the development and testing of a~new indicator-based pH sensor that meets all of these requirements. This sensor can withstand the rough conditions during long-term deployments on ships of opportunity and is applicable to the open ocean as well as to coastal waters with a complex matrix and highly variable conditions. The sensor uses a high resolution CCD spectrometer as detector connected via optical fibers to a custom-made cuvette designed to reduce the impact of air bubbles. The sample temperature can be precisely adjusted (25 °C ± 0.006 °C using computer-controlled power supplies and Peltier elements thus avoiding the widely used water bath. The overall setup achieves a measurement frequency of 1 min⁻¹ with a precision of ±0.0007 pH units, an average offset of +0.0005 pH units to a reference system, and an offset of +0.0081 pH units to a certified standard buffer. Application of this sensor allows monitoring of seawater pH in autonomous underway systems, providing a key variable for characterization and understanding of the marine carbon system.

Label-free silicon nanodots featured ratiometric fluorescent aptasensor for lysosomal imaging and pH measurement.

Science.gov (United States)

Zhang, Yanan; Guo, Shan; Cheng, Shibo; Ji, Xinghu; He, Zhike

2017-08-15

The homeostasis of lysosomal pH is crucial in cell physiology. Developing small fluorescent nanosensors for lysosome imaging and ratiometric measurement of pH is highly demanded yet challenging. Herein, a pH-sensitive fluorescein tagged aptamer AS1411 has been utilized to covalently modify the label-free fluorescent silicon nanodots via a crosslinker for construction of a ratiometric pH biosensor. The established aptasensor exhibits the advantages of ultrasmall size, hypotoxicity, excellent pH reversibility and good photostability, which favors its application in an intracellular environment. Using human breast MCF-7 cancer cells and MCF-10A normal cells as the model, this aptasensor shows cell specificity for cancer cells and displays a wide pH response range of 4.5-8.0 in living cells. The results demonstrate that the pH of MCF-7 cells is 5.1, which is the expected value for acidic organelles. Lysosome imaging and accurate measurement of pH in MCF-7 cells have been successfully conducted based on this nanosensor via fluorescent microscopy and flow cytometry. Copyright © 2017 Elsevier B.V. All rights reserved.

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

Detection of irradiated peppers by viscosity measurement at extremely high pH

International Nuclear Information System (INIS)

Hayashi, Toru; Todoriki, Setsuko

1996-01-01

The viscosities of aqueous suspensions of irradiated peppers determined after heat gelatinization were influenced by the pH of the suspension to a greater degree than those of unirradiated ones. Viscosity measurement under an extremely alkaline condition (pH 13.8) resulted in a significant different between irradiated peppers and unirradiated ones, irrespective of the planting locality and storage period. All of the pepper samples irradiated at 5 kGy showed viscosity values significantly lower than unirradiated ones. (Author)

pH Tolerance in Freshwater Bacterioplankton: Trait Variation of the Community as Measured by Leucine Incorporation

OpenAIRE

Bååth, Erland; Kritzberg, Emma

2015-01-01

pH is an important factor determining bacterial community composition in soil and water. We have directly determined the community tolerance (trait variation) to pH in communities from 22 lakes and streams ranging in pH from 4 to 9 using a growth-based method not relying on distinguishing between individual populations. The pH in the water samples was altered to up to 16 pH values, covering in situ pH ± 2.5 U, and the tolerance was assessed by measuring bacterial growth (Leu incorporation) in...

Characterization of PEBBLEs as a Tool for Real-Time Measurement of Dictyostelium discoideum Endosomal pH

Directory of Open Access Journals (Sweden)

Everett Moding

2009-01-01

Full Text Available The measurement of intracellular ion concentration change is important for understanding the cellular mechanisms for communication. Recently developed nanosensors, (Photonic Explorers for Biomedical use with Biologically Localized Embedding PEBBLEs, have a number of advantages for measuring ions in cells over established methods using microelectrodes, unbound fluorescent dyes, or NMR. PEBBLE sensors have been shown to work in principle for measuring dynamic ion changes, but few in vivo applications have been demonstrated. We modified the protocol for the fabrication of pH sensing PEBBLEs and developed a protocol for the utilization of these sensors for the monitoring of dynamic pH changes in the endosomes of slime mold Dictyostelium discoideum (D. discoideum. Oregon Green 514-CdSe Quantum Dot PEBBLEs were used to measure real-time pH inside D. discoideum endosomes during cAMP stimulation. Endosomal pH was shown to decrease during cAMP signaling, demonstrating a movement of protons into the endosomes of D. discoideum amoebae.

Skin physiology in men and women: in vivo evaluation of 300 people including TEWL, SC hydration, sebum content and skin surface pH.

Science.gov (United States)

Luebberding, S; Krueger, N; Kerscher, M

2013-10-01

Evidence is given that differences in skin physiological properties exist between men and women. However, despite an assessable number of available publications, the results are still inconsistent. Therefore, the aim of this clinical study is the first systematic assessment of gender-related differences in skin physiology in men and women, with a special focus on changes over lifetime. A total of 300 healthy male and female subjects (20-74 years) were selected following strict criteria including age, sun behaviour or smoking habits. TEWL, hydration level, sebum production and pH value were measured with worldwide-acknowledged biophysical measuring methods at forehead, cheek, neck, volar forearm and dorsum of hand. Until the age of 50 men's TEWL is significantly lower than the water loss of women of the same age, regardless of the location. With ageing gender-related differences in TEWL assimilate. Young men show higher SC hydration in comparison with women. But, whereas SC hydration is stable or even increasing in women over lifetime, the skin hydration in men is progressively decreasing, beginning at the age of 40. Sebum production in male skin is always higher and stays stable with increasing age, whereas sebum production in women progressively decreases over lifetime. Across all localizations and age groups, the pH value in men is below 5, the pH value of female subjects is, aside from limited expectations, higher than 5. Skin physiological distinctions between the sexes exist and are particularly remarkable with regard to sebum production and pH value. © 2013 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Drilling and associated drillhole measurements of the pilot hole ONK-PH12

International Nuclear Information System (INIS)

Toropainen, V.; Tarvainen, A.-M.; Poellaenen, J.; Pekkanen, J.; Pere, T.; Kaepyaho, E.; Lahti, M.

2011-01-01

The construction of the ONKALO access tunnel started in September 2004 at Olkiluoto. Most of the investigations related to the construction of the access tunnel aim to ensure successful excavations, reinforcement and sealing. Pilot holes are drillholes, which are core drilled along the tunnel profile. The length of the pilot holes typically varies from several tens of metres to a couple of hundred metres. The pilot holes are aimed to confirm the quality of the rock mass for tunnel construction, and in particular to identify water conductive fractured zones and to provide information that could result in modifications of the existing construction plans. The pilot hole ONK-PH12 was drilled from ONKALO chainage 4092 to chainage 4215 in January 2010. The length of the hole is 123.96 metres. The drilling method was orientated core drilling. The deviation of the drillhole was measured during and after the drilling phase. Electric conductivity was measured from the collected returning water samples. Logging of the core samples included the following parameters: lithology, foliation, fracturing, fracture frequency, RQD, fractured zones, core loss, and weathering. The rock mechanical logging was based on Q-classification. The test to determine rock strength and deformation were made with Rock Tester -equipment. Water conductivity of the fractures or fractured zones was measured by Posiva Flow Log equipment. The measurements were done in two phases. During flow measurements also grounding resistance electric conductivity and temperature were measured. In flow logging test, sections of 0.5 m with increments of 0.1 m were used. Water loss measurements were conducted in the drillhole section 5.0-123.85 m dhd. Geophysical logging as well as optical and acoustic imaging of the pilot hole included the fieldwork of all surveys, the integration of the data as well as interpretation of the acoustic and drillhole radar data. Groundwater sampling was not applicable because no

Biocompatible click chemistry enabled compartment-specific pH measurement inside E. coli.

Science.gov (United States)

Yang, Maiyun; Jalloh, Abubakar S; Wei, Wei; Zhao, Jing; Wu, Peng; Chen, Peng R

2014-09-19

Bioorthogonal reactions, especially the Cu(I)-catalysed azide-alkyne cycloaddition, have revolutionized our ability to label and manipulate biomolecules under living conditions. The cytotoxicity of Cu(I) ions, however, has hindered the application of this reaction in the internal space of living cells. By systematically surveying a panel of Cu(I)-stabilizing ligands in promoting protein labelling within the cytoplasm of Escherichia coli, we identify a highly efficient and biocompatible catalyst for intracellular modification of proteins by azide-alkyne cycloaddition. This reaction permits us to conjugate an environment-sensitive fluorophore site specifically onto HdeA, an acid-stress chaperone that adopts pH-dependent conformational changes, in both the periplasm and cytoplasm of E. coli. The resulting protein-fluorophore hybrid pH indicators enable compartment-specific pH measurement to determine the pH gradient across the E. coli cytoplasmic membrane. This construct also allows the measurement of E. coli transmembrane potential, and the determination of the proton motive force across its inner membrane under normal and acid-stress conditions.

Measurement of brain pH using 11CO2 and positron emission tomography

International Nuclear Information System (INIS)

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

1984-01-01

We have examined the feasibility of measuring local brain pH in vivo with 11 CO 2 and positron emission tomography. In particular, we have addressed two objections that have been raised against this method: the assumed need to estimate local tissue PCO 2 and the rapid fixation of 11 C in tissue. From a reexamination of the basic theory, we argue that after administration of 11 CO 2 the time-dependent distribution of 11 C between tissue and blood is independent of the distribution of CO 2 already in the body, making it unnecessary to estimate local tissue PCO 2 . Assuming that the blood--brain barrier is impermeable to bicarbonate ions, there will be equal partial pressures of 11 CO 2 in blood and tissue at equilibrium. To overcome the problem of fixation in the tissue we have developed a kinetic model of the time-dependent distribution of 11 C that accounts for regional variations in blood flow, CO 2 extraction, pH, and rate of fixation. The values of the model parameters can be estimated from sequential measurements of tissue activity concentration during administration of 11 CO 2 . Tissue pH can then be calculated from one of the parameter values, a measurement of arterial pH, and known constants. Numerical calculations based on the kinetic model with assumed values of the parameters were used to optimize the experimental design. The calculations show that problems with fixation are much less severe with continuous infusion of activity than with bolus administration. During infusion the tissue curve depends strongly on tissue pH but only weakly on the rate of fixation

Peptide-targeted delivery of a pH sensor for quantitative measurements of intraglycosomal pH in live Trypanosoma brucei.

Science.gov (United States)

Lin, Sheng; Morris, Meredith T; Ackroyd, P Christine; Morris, James C; Christensen, Kenneth A

2013-05-28

Studies of dynamic changes in organelles of protozoan parasite Trypanosoma brucei have been limited, in part because of the difficulty of targeting analytical probes to specific subcellular compartments. Here we demonstrate application of a ratiometric probe for pH quantification in T. brucei glycosomes. The probe consists of a peptide encoding the peroxisomal targeting sequence (F-PTS1, acetyl-CKGGAKL) coupled to fluorescein, which responds to pH. When incubated with living parasites, the probe is internalized within vesicular structures that colocalize with a glycosomal marker. Inhibition of uptake of F-PTS1 at 4 °C and pulse-chase colocalization with fluorescent dextran suggested that the probe is initially taken up by non-receptor-mediated endocytosis but is subsequently transported separately from dextran and localized within glycosomes, prior to the final fusion of labeled glycosomes and lysosomes as part of glycosomal turnover. Intraorganellar measurements and pH calibration with F-PTS1 in T. brucei glycosomes indicate that the resting glycosomal pH under physiological conditions is 7.4 ± 0.2. However, incubation in glucose-depleted buffer triggered mild acidification of the glycosome over a period of 20 min, with a final observed pH of 6.8 ± 0.3. This glycosomal acidification was reversed by reintroduction of glucose. Coupling of ratiometric fluorescent sensors and reporters to PTS peptides offers an invaluable tool for monitoring in situ glycosomal response(s) to changing environmental conditions and could be applied to additional kinetoplastid parasites.

Determination of very small contents of boron by pH difference measurement

International Nuclear Information System (INIS)

Boehm, H.; Kirmse, E.M.; Schilbach, U.

1983-01-01

For the determination of boron as a trace element for food of plants in a very complicated salt matrix an analytical proceeding was developed, which allows to determine the content of boron without separation. The principle of analysis is based on the esterification of boric acid with a multivalent alcohol, which leeds to a monovalent strong complex acid. The change of the pH value of the analysing solution is measured. From the initial pH number, the end pH number, the volume of the analysing solution and the ionic product of water corresponding with the operating temperature the quantity of boric acid of boron that is equivalent the produced quantity of H + -ions is calculated by means of a linear program. The standard deviation of analytical proceeding amounts to 13.9 ng B. For the determination of the contents of boron of an unknown sample, five to ten separate measurements are carried out. For solutions, which are about 1x10 -6 M of boric acid, there are necessary 10 ml of sample for each separate measurement. The confidence interval of analytical results is found to be between +- 0.5 and +- 15.5% (P=0.99). For the determination of the content of boron in plant materials about 50-100 mg of dry weight are necessary. (Author)

Polymeric gel nanoparticle pH sensors for intracellular measurements

DEFF Research Database (Denmark)

Almdal, Kristoffer; Andresen, Thomas Lars; Benjaminsen, Rikke Vicki

pH range is approximately 4 pH units and thus a nanoparticle sensor with two pH sensitive fluorophores is appropriate. With one pH sensitive fluorophore the output from the sensor follows R=R0+R1/10(pKa-pH), where R is the ratio of fluorescence for the two fluorophores, R0 is the minimum value of R...

Continuous measurement of intra-oral pH and temperature: development, validation of an appliance and a pilot study.

Science.gov (United States)

Choi, J E; Loke, C; Waddell, J N; Lyons, K M; Kieser, J A; Farella, M

2015-08-01

To describe a novel approach for continuous measurement of intra-oral pH and temperature in individuals carrying out normal daily activities over 24 h. We designed, validated and constructed a custom-made appliance fitted with a pH probe and a thermocouple. Six subjects wore the appliance over a 24-h period for two non-consecutive days, while the intra-oral pH and temperature were measured continuously and recorded. Intra-oral pH and temperature were very similar across different recording days, the difference being not statistically significant (P ≥ 0.14). There was a noticeable difference in the pattern of variation of pH between day and night. During the day, the mean pH was 7.3 (±0.4) and dropped markedly only after consumption of acidic food and drinks. The intra-oral pH decreased slowly during sleep with an average pH of 6.6 (±0.4) being recorded. The difference between day and night was statistically significant (P = 0.002). The mean intra-oral temperature was 33.9 °C (±0.9) during daytime and 35·9 °C (±0·5) during sleep (P = 0.013) with minor fluctuations occurring over 24 h. The continuous and simultaneous intra-oral pH and temperature measurement system described in this report is reliable, easy to construct, able to measure variables over a sustained period and may serve as a future diagnostic tool in a number of applications. © 2015 John Wiley & Sons Ltd.

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.

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

Metal/Metal Oxide Differential Electrode pH Sensors

Science.gov (United States)

West, William; Buehler, Martin; Keymeulen, Didier

2007-01-01

Solid-state electrochemical sensors for measuring the degrees of acidity or alkalinity (in terms of pH values) of liquid solutions are being developed. These sensors are intended to supplant older electrochemical pH sensors that include glass electrode structures and reference solutions. The older sensors are fragile and subject to drift. The present developmental solid-state sensors are more rugged and are expected to be usable in harsh environments. The present sensors are based on a differential-electrode measurement principle. Each sensor includes two electrodes, made of different materials, in equilibrium with the solution of interest.

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.

Cellular pH measurements in Emiliania huxleyi reveal pronounced membrane proton permeability.

Science.gov (United States)

Suffrian, K; Schulz, K G; Gutowska, M A; Riebesell, U; Bleich, M

2011-05-01

• To understand the influence of changing surface ocean pH and carbonate chemistry on the coccolithophore Emiliania huxleyi, it is necessary to characterize mechanisms involved in pH homeostasis and ion transport. • Here, we measured effects of changes in seawater carbonate chemistry on the fluorescence emission ratio of BCECF (2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein) as a measure of intracellular pH (pH(i)). Out of equilibrium solutions were used to differentiate between membrane permeation pathways for H(+), CO(2) and HCO(3)(-). • Changes in fluorescence ratio were calibrated in single cells, resulting in a ratio change of 0.78 per pH(i) unit. pH(i) acutely followed the pH of seawater (pH(e)) in a linear fashion between pH(e) values of 6.5 and 9 with a slope of 0.44 per pH(e) unit. pH(i) was nearly insensitive to changes in seawater CO(2) at constant pH(e) and HCO(3)(-). An increase in extracellular HCO(3)(-) resulted in a slight intracellular acidification. In the presence of DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid), a broad-spectrum inhibitor of anion exchangers, E. huxleyi acidified irreversibly. DIDS slightly reduced the effect of pH(e) on pH(i). • The data for the first time show the occurrence of a proton permeation pathway in E. huxleyi plasma membrane. pH(i) homeostasis involves a DIDS-sensitive mechanism. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

Drilling and associated Drillhole measurements of the Pilot Hole ONK-PH14

International Nuclear Information System (INIS)

Aalto, P.; Toropainen, V.; Tarvainen, A.-M.; Pekkanen, J.; Poellaenen, J.; Lamminmaeki, T.

2011-09-01

The construction of ONKALO access tunnel started in September 2004 at Olkiluoto. During the construction, investigations serving both research and construction purposes need to be done. Investigations can be done for example in so called pilot holes. Pilot holes are cored drillholes to be drilled to the tunnel profile. The length of the holes varies from some tens of metres to some hundreds of metres. The purpose of the holes is to confirm the quality of the rock mass for tunnel construction, especially to identify water conductive fractures/fractured zones and to provide information that could result in modifications of the existing construction plans. The pilot hole ONK-PH14 was drilled in June 2010. Drilling was started in chainage 4313.6. The length of the hole was 150.80 metres. The deviation of the drillhole was measured during and after the drilling. Additionally, oriented core samples were collected from the drill core and the electric conductivity of returning water was measured. Logging of the core samples included following parameters: lithology, foliation, fracturing, fracture frequency, RQD, fractured zones, core loss and weathering. The rock mechanical logging was based on Q-classification. The strength and deformation properties of the rock were defined by using Rock-Tester equipment. Hydraulic measurements were made by using the PFL DIFF (Posiva Flow log, Difference Flow Method). PFL DIFF measurements were performed with a 0.5 m section length and with 0.1 m length increments. With PFL DIFF tool the locations of transmissive fractures were detected. Simultaneously, the electric conductivity (EC) of the drillhole water and fracture specific water, temperature of the drillhole water, single point resistance (SPR) of the drillhole wall and the prevailing water pressure were measured. Water loss measurements were done after the drilling by the tool developed by Posiva. The tool was in test use during the measurements. The groundwater sample was

Drilling and associated Drillhole measurements of the Pilot Hole ONK-PH14

Energy Technology Data Exchange (ETDEWEB)

Aalto, P. (ed.); Lahti, M.; Kosunen, P.; Pere, T. [Posiva Oy, Helsinki (Finland); Toropainen, V.; Tarvainen, A.-M. [Suomen Malmi Oy, Espoo (Finland); Pekkanen, J.; Poellaenen, J. [Poeyry Finland Oy, Espoo (Finland); Lamminmaeki, T. [Teollisuuden Voima Oyj, Helsinki (Finland)

2011-08-15

The construction of ONKALO access tunnel started in September 2004 at Olkiluoto. During the construction, investigations serving both research and construction purposes need to be done. Investigations can be done for example in so called pilot holes. Pilot holes are cored drillholes to be drilled to the tunnel profile. The length of the holes varies from some tens of metres to some hundreds of metres. The purpose of the holes is to confirm the quality of the rock mass for tunnel construction, especially to identify water conductive fractures/fractured zones and to provide information that could result in modifications of the existing construction plans. The pilot hole ONK-PH14 was drilled in June 2010. Drilling was started in chainage 4313.6. The length of the hole was 150.80 metres. The deviation of the drillhole was measured during and after the drilling. Additionally, oriented core samples were collected from the drill core and the electric conductivity of returning water was measured. Logging of the core samples included following parameters: lithology, foliation, fracturing, fracture frequency, RQD, fractured zones, core loss and weathering. The rock mechanical logging was based on Q-classification. The strength and deformation properties of the rock were defined by using Rock-Tester equipment. Hydraulic measurements were made by using the PFL DIFF (Posiva Flow log, Difference Flow Method). PFL DIFF measurements were performed with a 0.5 m section length and with 0.1 m length increments. With PFL DIFF tool the locations of transmissive fractures were detected. Simultaneously, the electric conductivity (EC) of the drillhole water and fracture specific water, temperature of the drillhole water, single point resistance (SPR) of the drillhole wall and the prevailing water pressure were measured. Water loss measurements were done after the drilling by the tool developed by Posiva. The tool was in test use during the measurements. The groundwater sample was

Measurement of the internal pH of mast cell granules using microvolumetric fluorescence and isotopic techniques

International Nuclear Information System (INIS)

De Young, M.B.; Nemeth, E.F.; Scarpa, A.

1987-01-01

The intragranular pH of isolated mast cell granules was measured. Because of the minute amounts of isolated granules available, two techniques were developed by modifying aminoacridine fluorescence and [ 14 C]methylamine accumulation techniques to permit measurements with microliter sample volumes. Granule purity was demonstrated by electron microscopy, ruthenium red exclusion, and biochemical (histamine, mast cell granule protease) analysis. The internal pH was determined to be 5.55 +/- 0.06, indicating that the pH environment within mast cell granules is not significantly different from that of previously studied granule types (i.e., chromaffin, platelet, pancreatic islet, and pituitary granules). Collapse of the pH gradient by NH+4 was demonstrated with both techniques. No evidence of Cl-/OH- or specific cation/H+ transport was found, and major chloride permeability could not be unequivocably demonstrated. Ca 2+ and Cl- at concentrations normally present extracellularly destabilized granules in the presence of NH+4, but this phenomenon does not necessarily indicate a role for these ions in the exocytotic release of granule contents from intact cells. The pH measurement techniques developed for investigating the properties of granules in mast cells may be useful for studying other granules that can be obtained only in limited quantities

Assessment of Tandem Measurements of pH and Total Gut Transit Time in Healthy Volunteers

OpenAIRE

Mikolajczyk, Adam E; Watson, Sydeaka; Surma, Bonnie L; Rubin, David T

2015-01-01

Objectives: The variation of luminal pH and transit time in an individual is unknown, yet is necessary to interpret single measurements. This study aimed to assess the intrasubject variability of gut pH and transit time in healthy volunteers using SmartPill devices (Covidien, Minneapolis, MN). Methods: Each subject (n=10) ingested two SmartPill devices separated by 24?h. Mean pH values were calculated for 30?min after gastric emptying (AGE), before the ileocecal (BIC) valve, after the ileocec...

Solid State Sensor for Simultaneous Measurement of Total Alkalinity and pH of Seawater.

Science.gov (United States)

Briggs, Ellen M; Sandoval, Sergio; Erten, Ahmet; Takeshita, Yuichiro; Kummel, Andrew C; Martz, Todd R

2017-09-22

A novel design is demonstrated for a solid state, reagent-less sensor capable of rapid and simultaneous measurement of pH and Total Alkalinity (A T ) using ion sensitive field effect transistor (ISFET) technology to provide a simplified means of characterization of the aqueous carbon dioxide system through measurement of two "master variables": pH and A T . ISFET-based pH sensors that achieve 0.001 precision are widely used in various oceanographic applications. A modified ISFET is demonstrated to perform a nanoliter-scale acid-base titration of A T in under 40 s. This method of measuring A T , a Coulometric Diffusion Titration, involves electrolytic generation of titrant, H + , through the electrolysis of water on the surface of the chip via a microfabricated electrode eliminating the requirement of external reagents. Characterization has been performed in seawater as well as titrating individual components (i.e., OH - , HCO 3 - , CO 3 2- , B(OH) 4 - , PO 4 3- ) of seawater A T . The seawater measurements are consistent with the design in reaching the benchmark goal of 0.5% precision in A T over the range of seawater A T of ∼2200-2500 μmol kg -1 which demonstrates great potential for autonomous sensing.

Validation of the measurement of pH in water of the secondary circuit in the range 9 to 10 at 25 deg. C

International Nuclear Information System (INIS)

Gorgoschidse, Marina; Zilli, Mariano; Echeverria, Paola; Schonbord, Betina

2012-09-01

pH measurement is a control parameter used for water conditioning in the secondary circuit at Atucha Nuclear Plant. As such it is an important indicator of the protection of structural components against corrosion. Its magnitude and importance determines the dosing and selection appropriate chemical agents for using in the CNAI's, therefore the need, for a measurement methodology validation. A pH measurement made in the wrong way can lead the deterioration due the alkaline environment in which we are working. In this paper we review the methods to study various experimental parameters involved in the measurements: characteristics of the state of the electrochemical cell, including measurement time, liquid junction and agitation error. Lastly, results are described in terms of precision parameters (repeatability and reproducibility) and accuracy (authors)

Self-Assembled Fluorescent Bovine Serum Albumin Nanoprobes for Ratiometric pH Measurement inside Living Cells.

Science.gov (United States)

Yang, Qiaoyu; Ye, Zhongju; Zhong, Meile; Chen, Bo; Chen, Jian; Zeng, Rongjin; Wei, Lin; Li, Hung-wing; Xiao, Lehui

2016-04-20

In this work, we demonstrated a new ratiometric method for the quantitative analysis of pH inside living cells. The structure of the nanosensor comprises a biofriendly fluorescent bovine serum albumin (BSA) matrix, acting as a pH probe, and pH-insensitive reference dye Alexa 594 enabling ratiometric quantitative pH measurement. The fluorescent BSA matrix was synthesized by cross-linking of the denatured BSA proteins in ethanol with glutaraldehyde. The size of the as-synthesized BSA nanoparticles can be readily manipulated from 30 to 90 nm, which exhibit decent fluorescence at the peak wavelength of 535 nm with a pH response range of 6-8. The potential of this pH sensor for intracellular pH monitoring was demonstrated inside living HeLa cells, whereby a significant change in fluorescence ratio was observed when the pH of the cell was switched from normal to acidic with anticancer drug treatment. The fast response of the nanosensor makes it a very powerful tool in monitoring the processes occurring within the cytosol.

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.

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...

pH homeostasis in Escherichia coli: measurement by 31P nuclear magnetic resonance of methylphosphonate and phosphate

International Nuclear Information System (INIS)

Slonczewski, J.L.; Rosen, B.P.; Alger, J.R.; Macnab, R.M.

1981-01-01

The intracellular pH of Escherichia coli cells, respiring on endogenous energy sources, was monitored continuously by 31 P NMR over an extracellular pH range between 5.5 and 9. pH homeostasis was found to be good over the entire range, with the data conforming to the simple relationship intracellular pH = 7.6 + 0.1(external pH - 7.6) so that the extreme values observed for intracellular pH were 7.4 and 7.8 external pH 5.5 and 9, respectively. As well as inorganic phosphate, we employed the pH-sensitive NMR probe methylphosphonate, which was taken up by glycerol-grown cells and was nontoxic; its pK/sub a/ of 7.65 made it an ideal probe for measurement of cytoplasmic pH and alkaline external pH

pH tolerance in freshwater bacterioplankton: trait variation of the community as measured by leucine incorporation.

Science.gov (United States)

Bååth, Erland; Kritzberg, Emma

2015-11-01

pH is an important factor determining bacterial community composition in soil and water. We have directly determined the community tolerance (trait variation) to pH in communities from 22 lakes and streams ranging in pH from 4 to 9 using a growth-based method not relying on distinguishing between individual populations. The pH in the water samples was altered to up to 16 pH values, covering in situ pH ± 2.5 U, and the tolerance was assessed by measuring bacterial growth (Leu incorporation) instantaneously after pH adjustment. The resulting unimodal response curves, reflecting community tolerance to pH, were well modeled with a double logistic equation (mean R(2) = 0.97). The optimal pH for growth (pHopt) among the bacterial communities was closely correlated with in situ pH, with a slope (0.89 ± 0.099) close to unity. The pH interval, in which growth was ≥90% of that at pHopt, was 1.1 to 3 pH units wide (mean 2.0 pH units). Tolerance response curves of communities originating from circum-neutral pH were symmetrical, whereas in high-pH (8.9) and especially in low-pH (pH waters, decreasing pH was more detrimental for bacterial growth than increasing pH, with a tendency for the opposite for high-pH waters. A pH tolerance index, using the ratio of growth at only two pH values (pH 4 and 8), was closely related to pHopt (R(2) = 0.83), allowing for easy determination of pH tolerance during rapid changes in pH. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Gravity-driven pH adjustment for site-specific protein pKa measurement by solution-state NMR

Science.gov (United States)

Li, Wei

2017-12-01

To automate pH adjustment in site-specific protein pKa measurement by solution-state NMR, I present a funnel with two caps for the standard 5 mm NMR tube. The novelty of this simple-to-build and inexpensive apparatus is that it allows automatic gravity-driven pH adjustment within the magnet, and consequently results in a fully automated NMR-monitored pH titration without any hardware modification on the NMR spectrometer.

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...

A new approach to pH of point of zero charge measurement: crystal-face specificity by scanning force microscopy (SFM)

Science.gov (United States)

Eggleston, Carrick M.; Jordan, Guntram

1998-06-01

The pH of point of zero charge (pH pzc) is a fundamentally important property used in modeling the interaction of solid surfaces with aqueous solutions and solutes. The pH pzc is normally measured by acid-base titration of solid suspensions. Here, a scanning force microscope (SFM) is used to measure forces of repulsion or attraction between chemically tailored tips and quartz (101) and hematite (001) surfaces, as a function of tip-surface separation and pH. The force at contact (FAC) is at a minimum near the expected point of pH pzc for a chemically similar tip and sample. The results are compared to predicted interaction forces from a simple DLVO model, which shows that the SFM technique for pH pzc measurement is most promising for surfaces (such as iron oxides) that have not-too-widely spaced pK a1 and pK a2 values for surface site deprotonation. However, improvements in precision will be necessary to fully utilize the technique. The SFM approach to pH pzc measurement may in future allow the measurement of crystal-face-specific pH pzc, rather than a weighted average of all exposed surface sites, and thus allow us to ask better-defined structure-reactivity questions for mineral surfaces. The approach can in theory be extended to the single-site scale in order to probe the properties (e.g., potential and charge) of individual terrace, step, or kink sites.

Measurement of pH micro-heterogeneity in natural cheese matrices by flourescence lifetime imaging

OpenAIRE

Burdikova, Suzana; Svindrych, Zdenek; Pala, Jan; Hickey, Cian D; Wilkinson, Martin G.; Panek, Jiri; Auty, Mark A.E.; Periasamy, Ammasi; Sheehan, Jeremiah J.

2015-01-01

peer-reviewed Cheese, a product of microbial fermentation may be defined as a protein matrix entrapping fat, moisture, minerals and solutes as well as dispersed bacterial colonies. The growth and physiology of bacterial cells in these colonies may be influenced by the microenvironment around the colony, or alternatively the cells within the colony may modify the microenvironment (e.g., pH, redox potential) due to their metabolic activity. While cheese pH may be measured at macro level ther...

Noninvasive, near infrared spectroscopic-measured muscle pH and PO2 indicate tissue perfusion for cardiac surgical patients undergoing cardiopulmonary bypass

Science.gov (United States)

Soller, Babs R.; Idwasi, Patrick O.; Balaguer, Jorge; Levin, Steven; Simsir, Sinan A.; Vander Salm, Thomas J.; Collette, Helen; Heard, Stephen O.

2003-01-01

OBJECTIVE: To determine whether near infrared spectroscopic measurement of tissue pH and Po2 has sufficient accuracy to assess variation in tissue perfusion resulting from changes in blood pressure and metabolic demand during cardiopulmonary bypass. DESIGN: Prospective clinical study. SETTING: Academic medical center. SUBJECTS: Eighteen elective cardiac surgical patients. INTERVENTION: Cardiac surgery under cardiopulmonary bypass. MEASUREMENTS AND MAIN RESULTS: A near infrared spectroscopic fiber optic probe was placed over the hypothenar eminence. Reference Po2 and pH sensors were inserted in the abductor digiti minimi (V). Data were collected every 30 secs during surgery and for 6 hrs following cardiopulmonary bypass. Calibration equations developed from one third of the data were used with the remaining data to investigate sensitivity of the near infrared spectroscopic measurement to physiologic changes resulting from cardiopulmonary bypass. Near infrared spectroscopic and reference pH and Po2 measurements were compared for each subject using standard error of prediction. Near infrared spectroscopic pH and Po2 at baseline were compared with values during cardiopulmonary bypass just before rewarming commenced (hypotensive, hypothermic), after rewarming (hypotensive, normothermic) just before discontinuation of cardiopulmonary bypass, and at 6 hrs following cardiopulmonary bypass (normotensive, normothermic) using mixed-model analysis of variance. Near infrared spectroscopic pH and Po2 were well correlated with the invasive measurement of pH (R2 =.84) and Po2 (R 2 =.66) with an average standard error of prediction of 0.022 +/- 0.008 pH units and 6 +/- 3 mm Hg, respectively. The average difference between the invasive and near infrared spectroscopic measurement was near zero for both the pH and Po2 measurements. Near infrared spectroscopic Po2 significantly decreased 50% on initiation of cardiopulmonary bypass and remained depressed throughout the bypass and

Polymeric nanosensors for measuring the full dynamic pH range of endosomes and lysosomes in mammalian cells

DEFF Research Database (Denmark)

Sun, Honghao; Andresen, Thomas Lars; Benjaminsen, Rikke Vicki

2009-01-01

Polymer nanoparticle sensors have been constructed for studying pH in the endocytic pathway in mammalian cells. The pH sensors for fluorescence ratiometric measurements were prepared using inverse microemulsion polymerization with rhodamine as reference fluorophor and fluorescein and oregon green...... was used to introduce a net positive charge in the cationic particles. It was found that the positively charged particle sensors were internalized spontaneously by HepG2 cancer cells. These new pH nanosensors are potential tools in time resolved quantification of pH in the endocytic pathway of living cells....

Measurement of pH micro-heterogeneity in natural cheese matrices by fluorescence lifetime imaging

OpenAIRE

Zuzana eBurdikova; Zdenek eSvindrych; Jan ePala; Cian eHickey; Martin G. Wilkinson; Jiri ePanek; Mark A. E. Auty; Ammasi ePeriasamy; Jeremiah J. Sheehan

2015-01-01

Cheese, a product of microbial fermentation may be defined as a protein matrix entrapping fat, moisture, minerals and solutes as well as dispersed bacterial colonies. The growth and physiology of bacterial cells in these colonies may be influenced by the microenvironment around the colony, or alternatively the cells within the colony may modify the microenvironment (e.g., pH, redox potential) due to their metabolic activity. While cheese pH may be measured at macro level there remains a signi...

Time-to-Fatigue and Intramuscular pH Measured via NIRS During Handgrip Exercise in Trained and Sedentary Individuals

Science.gov (United States)

Everett, M. E.; Lee, S. M. C.; Stroud, L.; Scott, P.; Hagan, R. D.; Soller, B. R.

2009-01-01

In exercising muscles force production and muscular endurance are impaired by a decrease in intramuscular pH. The effects of aerobic training (AT) on preventing acidosis and prolonging exercise time in muscles not specifically targeted by the training are unknown. Purpose: To compare interstitial pH, measured non-invasively with near infrared spectroscopy (NIRS), in the flexor digitorum profundus (FDP) during rhythmic handgrip exercise in sedentary subjects and those who participate in AT activities that target the lower body. Methods: Maximal isometric force (MIF) was measured on three separate days in AT (n=5) and sedentary (n=8) subjects using a handgrip dynamometer (HGD). Isometric muscular endurance (IME) was measured during five trials, each separated by at least 48 hrs. For each IME trial subjects rhythmically squeezed (4 sec at 40% of MVC) and relaxed (2 sec) to fatigue or failure to reach the target force in three consecutive contractions or four non-consecutive contractions. Interstitial pH was derived from spectra collected using a NIRS sensor adhered to the skin over the FDP. The first four IME trials served to familiarize subjects with the protocol; the fifth trial was used for analysis. NIRS-derived pH was averaged in 30 sec increments. Between group differences in MIF and exercise time were tested using paired t-tests. A repeated measures ANOVA was used to analyze effects of AT and exercise time on pH. Results: MIF was not different between groups (mean SD; aerobic=415.6 95.4 N vs. sedentary =505.1 107.4 N). Time to fatigue was greater in the AT than in the sedentary group (mean SD: 611 173 sec vs. 377 162 sec, p<0.05). pH was not different between groups at any time point. Average pH decreased (p<0.05) in both groups from rest (pH=7.4) through 90 sec of exercise (pH=6.9), but did not decrease further throughout the remainder of exercise. Conclusion: Although between group differences in pH were not detected, differences during the onset of exercise

Development of novel Sol-Gel Indicators (SGI's) for in-situ environmental measurements: Part 1, Program and a new pH Sol-Gel Indicator

International Nuclear Information System (INIS)

Livingston, R.R.; Baylor, L.; Wicks, G.G.

1992-01-01

The feasibility of incorporating analytical indicators into a sol-gel glassy matrix and then coating substrates with this composite material has bee demonstrated. Substrates coated include paper, wood, glass, and the lens of an analytical probe. The first SRTC sol-gel indicator, comprising bromophenol blue dispersed in a silica matrix, was fabricated and successfully used to measure solution pH in the range of pH 3.0 to 7.5. material exhibited a quick response time, as measured by color changes both qualitatively and quantitatively, and the measuring device was reversible or reusable. Additional indicators with responses over other ranges as well as indicators sensitive to the presence of elements of interest, are also under development. The new SGI composites possess promising properties and an excellent potential for performing a variety important in-situ environmental measurements and area discussed in this report

pH-Free Measurement of Relative Acidities, Including Isotope Effects.

Science.gov (United States)

Perrin, Charles L

2017-01-01

A powerful pH-free multicomponent NMR titration method can measure relative acidities, even of closely related compounds, with excellent accuracy. The history of the method is presented, along with details of its implementation and a comparison with earlier NMR titrations using a pH electrode. Many of its areas of applicability are described, especially equilibrium isotope effects. The advantages of the method, some practical considerations, and potential pitfalls are considered. © 2017 Elsevier Inc. All rights reserved.

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.

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.

Microfabricated Collector-Generator Electrode Sensor for Measuring Absolute pH and Oxygen Concentrations.

Science.gov (United States)

Dengler, Adam K; Wightman, R Mark; McCarty, Gregory S

2015-10-20

Fast-scan cyclic voltammetry (FSCV) has attracted attention for studying in vivo neurotransmission due to its subsecond temporal resolution, selectivity, and sensitivity. Traditional FSCV measurements use background subtraction to isolate changes in the local electrochemical environment, providing detailed information on fluctuations in the concentration of electroactive species. This background subtraction removes information about constant or slowly changing concentrations. However, determination of background concentrations is still important for understanding functioning brain tissue. For example, neural activity is known to consume oxygen and produce carbon dioxide which affects local levels of oxygen and pH. Here, we present a microfabricated microelectrode array which uses FSCV to detect the absolute levels of oxygen and pH in vitro. The sensor is a collector-generator electrode array with carbon microelectrodes spaced 5 μm apart. In this work, a periodic potential step is applied at the generator producing transient local changes in the electrochemical environment. The collector electrode continuously performs FSCV enabling these induced changes in concentration to be recorded with the sensitivity and selectivity of FSCV. A negative potential step applied at the generator produces a transient local pH shift at the collector. The generator-induced pH signal is detected using FSCV at the collector and correlated to absolute solution pH by postcalibration of the anodic peak position. In addition, in oxygenated solutions a negative potential step at the generator produces hydrogen peroxide by reducing oxygen. Hydrogen peroxide is detected with FSCV at the collector electrode, and the magnitude of the oxidative peak is proportional to absolute oxygen concentrations. Oxygen interference on the pH signal is minimal and can be accounted for with a postcalibration.

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.

Synthesis and Characterization of a Micelle-Based pH Nanosensor with an Unprecedented Broad Measurement Range

DEFF Research Database (Denmark)

Ek, Pramod Kumar; Feldborg, Lise N.; Almdal, Kristoffer

2013-01-01

A new cross-linked micelle pH nanosensor design was investigated. The nanosensor synthesis was based on self-assembly of an amphiphilic triblock copolymer, poly(ethylene glycol)-b-poly(2-amino ethyl methacrylate)-b-poly(coumarin methacrylate) (PEG-b-PAEMA-b-PCMA), which was synthesized by isolated...... irradiation (320 nm pH nanosensors by binding the pH-sensitive fluorophores oregon green 488 and 2′,7′-bis-(2-carboxyethyl)-5-(and-6......) carboxyfluorescein and a reference fluorophore Alexa 633 to the PAEMA shell region of the micelles. Fluorescence measurements show that these pH nanosensors are sensitive in a surprisingly broad pH range of 3.4–8.0, which is hypothesized to be due to small differences in the individual fluorophores’ local...

Potential of on-line visible and near infrared spectroscopy for measurement of pH for deriving variable rate lime recommendations.

Science.gov (United States)

Tekin, Yücel; Kuang, Boyan; Mouazen, Abdul M

2013-08-08

This paper aims at exploring the potential of visible and near infrared (vis-NIR) spectroscopy for on-line measurement of soil pH, with the intention to produce variable rate lime recommendation maps. An on-line vis-NIR soil sensor set up to a frame was used in this study. Lime application maps, based on pH predicted by vis-NIR techniques, were compared with maps based on traditional lab-measured pH. The validation of the calibration model using off-line spectra provided excellent prediction accuracy of pH (R2 = 0.85, RMSEP = 0.18 and RPD = 2.52), as compared to very good accuracy obtained with the on-line measured spectra (R2 = 0.81, RMSEP = 0.20 and RPD = 2.14). On-line predicted pH of all points (e.g., 2,160) resulted in the largest overall field virtual lime requirement (1.404 t), as compared to those obtained with 16 validation points off-line prediction (0.28 t), on-line prediction (0.14 t) and laboratory reference measurement (0.48 t). The conclusion is that the vis-NIR spectroscopy can be successfully used for the prediction of soil pH and for deriving lime recommendations. The advantage of the on-line sensor over sampling with limited number of samples is that more detailed information about pH can be obtained, which is the reason for a higher but precise calculated lime recommendation rate.

Potential of On-Line Visible and Near Infrared Spectroscopy for Measurement of pH for Deriving Variable Rate Lime Recommendations

Directory of Open Access Journals (Sweden)

Yücel Tekin

2013-08-01

Full Text Available This paper aims at exploring the potential of visible and near infrared (vis-NIR spectroscopy for on-line measurement of soil pH, with the intention to produce variable rate lime recommendation maps. An on-line vis-NIR soil sensor set up to a frame was used in this study. Lime application maps, based on pH predicted by vis-NIR techniques, were compared with maps based on traditional lab-measured pH. The validation of the calibration model using off-line spectra provided excellent prediction accuracy of pH (R2 = 0.85, RMSEP = 0.18 and RPD = 2.52, as compared to very good accuracy obtained with the on-line measured spectra (R2 = 0.81, RMSEP = 0.20 and RPD = 2.14. On-line predicted pH of all points (e.g., 2,160 resulted in the largest overall field virtual lime requirement (1.404 t, as compared to those obtained with 16 validation points off-line prediction (0.28 t, on-line prediction (0.14 t and laboratory reference measurement (0.48 t. The conclusion is that the vis-NIR spectroscopy can be successfully used for the prediction of soil pH and for deriving lime recommendations. The advantage of the on-line sensor over sampling with limited number of samples is that more detailed information about pH can be obtained, which is the reason for a higher but precise calculated lime recommendation rate.

Measuring efficiency of university-industry Ph.D. projects using best worst method.

Science.gov (United States)

Salimi, Negin; Rezaei, Jafar

A collaborative Ph.D. project, carried out by a doctoral candidate, is a type of collaboration between university and industry. Due to the importance of such projects, researchers have considered different ways to evaluate the success, with a focus on the outputs of these projects. However, what has been neglected is the other side of the coin-the inputs. The main aim of this study is to incorporate both the inputs and outputs of these projects into a more meaningful measure called efficiency. A ratio of the weighted sum of outputs over the weighted sum of inputs identifies the efficiency of a Ph.D. The weights of the inputs and outputs can be identified using a multi-criteria decision-making (MCDM) method. Data on inputs and outputs are collected from 51 Ph.D. candidates who graduated from Eindhoven University of Technology. The weights are identified using a new MCDM method called Best Worst Method (BWM). Because there may be differences in the opinion of Ph.D. candidates and supervisors on weighing the inputs and outputs, data for BWM are collected from both groups. It is interesting to see that there are differences in the level of efficiency from the two perspectives, because of the weight differences. Moreover, a comparison between the efficiency scores of these projects and their success scores reveals differences that may have significant implications. A sensitivity analysis divulges the most contributing inputs and outputs.

Drilling and associated drillhole measurements of the pilot hole ONK-PH11

International Nuclear Information System (INIS)

Karttunen, P.; Mancini, P.; Pekkanen, J.; Poellaenen, J.; Tarvainen, A.-M.; Toropainen, V.; Pere, T.

2011-01-01

The construction of the ONKALO access tunnel started in September 2004 at Olkiluoto. Most of the investigations related to the construction of the access tunnel aim to ensure successful excavations, reinforcement and sealing. Pilot holes are drillholes, which are core drilled along the tunnel profile. The length of the pilot holes typically varies from several tens of metres to a couple of hundred metres. The pilot holes are aimed to confirm the quality of the rock mass for tunnel construction, and in particular to identify water conductive fractured zones and to provide information that could result in modifications of the existing construction plans. The pilot hole ONK-PH11 was drilled from chainage 3922 to chainage 4053 in October 2009. The length of the hole is 131.21 metres. The aim during the drilling work was to orient core samples as much as possible. The deviation of the drillhole was measured during and after the drilling phase. Electric conductivity was measured from the collected returning water samples. Hydraulic conductivity of the fractures or fractured zones was measured by Posiva Flow Log equipment. During flow measurements also electric conductivity and temperature were measured. In flow logging test sections of 0.5 m and increments of 0.1 m were used. The water loss measurements were performed after drilling was completed by the drilling company. Logging of the core samples included the following parameters: lithology, foliation, fracturing, RQD, fractured zones, weathering and possible intersections. The rock mechanical logging was based on Q-classification. The rock strength and deformation were determined with Rock Tester -equipment. Geophysical logging and optical imaging of the pilot hole included the fieldwork of all surveys, the integration of the data as well as interpretation of the acoustic and drillhole radar data. The groundwater samples were collected from the open hole without any packers. The collected groundwater samples were

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.

Scintigraphy, pH measurement and radiography in the evaluation of gastroesophageal reflux

International Nuclear Information System (INIS)

Kaul, B.; Petersen, H.; Grette, K.; Erichsen, H.; Myrvold, H.E.

1985-01-01

Scintigraphy as a diagnostic tool has been explored in 69 patients with gastroesophageal reflux (GER) symptoms and endoscopic esophagitis. In all subjects the presence of reflux was also evaluated by radiography and intraesophageal pH measurements (standard acid reflux test). The overall sensitivity of scintigraphy (85.5%) was significantly higher than those of radiography (27.5%) and pH measurements (69.5%). Scintigraphy was performed with normal saline and with acidified orange juice as the transport medium for the isotope 99mTc. The yield of positive scintigrams was higher (22.3 to 61.1%, depending on the grade of endoscopic esophagitis) with the latter variant. Moreover, demonstration of spontaneous reflux was greatly facilitated by the acid scintigraphy. This was particularly obvious in the grade I esophagitis, in which the freqency of spontaneous reflux with saline method was 3.4% and with acid medium 34/3%. Reflux (induced or spontaneous) was seen in 22 normal control subjects with the saline method, and in 1 subject only with the acid method. On the basis of these findings it is concluded that scintigraphy, especially the acid variant of the technique, is a valuable diagnostic procedure in GER disease

Scintigraphy, pH measurement and radiography in the evaluation of gastroesophageal reflux

Energy Technology Data Exchange (ETDEWEB)

Kaul, B.; Petersen, H.; Grette, K.; Erichsen, H.; Myrvold, H.E.

1985-01-01

Scintigraphy as a diagnostic tool has been explored in 69 patients with gastroesophageal reflux (GER) symptoms and endoscopic esophagitis. In all subjects the presence of reflux was also evaluated by radiography and intraesophageal pH measurements (standard acid reflux test). The overall sensitivity of scintigraphy (85.5%) was significantly higher than those of radiography (27.5%) and pH measurements (69.5%). Scintigraphy was performed with normal saline and with acidified orange juice as the transport medium for the isotope 99mTc. The yield of positive scintigrams was higher (22.3 to 61.1%, depending on the grade of endoscopic esophagitis) with the latter variant. Moreover, demonstration of spontaneous reflux was greatly facilitated by the acid scintigraphy. This was particularly obvious in the grade I esophagitis, in which the freqency of spontaneous reflux with saline method was 3.4% and with acid medium 34/3%. Reflux (induced or spontaneous) was seen in 22 normal control subjects with the saline method, and in 1 subject only with the acid method. On the basis of these findings it is concluded that scintigraphy, especially the acid variant of the technique, is a valuable diagnostic procedure in GER disease.

Recent Developments in R.F. Magnetron Sputtered Thin Films for pH Sensing Applications—An Overview

OpenAIRE

D. K. Maurya; A. Sardarinejad; K. Alameh

2014-01-01

pH sensors are widely used in chemical and biological applications. Metal oxides-based pH sensors have many attractive features including insolubility, stability, mechanical strength, electrocatalyst and manufacturing technology. Various metal oxide thin films prepared by radio frequency (R.F.) magnetron sputtering have attractive features, including high pH sensitivity, fast response, high resolution, good stability and reversibility as well as potential for measuring pH under conditions th...

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)

Drilling and associated drillhole measurements of the pilot hole ONK-PH9

International Nuclear Information System (INIS)

Karttunen, P.; Pekkanen, J.; Poellaenen, J.; Tarvainen, A.-M.; Toropainen, V.; Lamminmaeki, T.; Kosunen, P.

2010-01-01

The construction of the ONKALO access tunnel started in September 2004 at Olkiluoto. Most of the investigations related to the construction of the access tunnel aim to ensure successful excavations, reinforcement and sealing. Pilot holes are drillholes, which are core drilled along the tunnel profile. The length of the pilot holes typically varies from several tens of metres to a couple of hundred metres. The pilot holes are aimed to confirm the quality of the rock mass for tunnel construction, and in particular to identify water conductive fractured zones and to provide information that could result in modifications of the existing construction plans. The pilot hole ONK-PH9 was drilled from chainage 3263 to chainage 3413.27 in November 2008. The length of the hole is 150.3 metres. The aim during the drilling work was to orient core samples as much as possible. The deviation of the drillhole was measured during and after the drilling phase. Electric conductivity was measured from the collected returning water samples. Hydraulic conductivity of the fractures or fractured zones was measured by Posiva Flow Log equipment. The measurements were done in two phases. During flow measurements also electric conductivity, grounding resistance and temperature were measured. In flow logging test sections of 0.5 m and increments of 0.1 m were used. The water loss measurements were performed after drilling was completed by the drilling company. Logging of the core samples included the following parameters: lithology, foliation, fracturing, fracture frequency, RQD, fractured zones, core loss, and weathering. The rock mechanical logging was based on Q-classification. The rock strength and deformation were determined with Rock Tester equipment. Geophysical logging and optical imaging of the pilot hole included the fieldwork of all surveys, the integration of the data as well as interpretation of the acoustic and drillhole radar data. One of the objectives of the geochemical study

Drilling and associated drillhole measurements of the pilot hole ONK-PH10

International Nuclear Information System (INIS)

Mancini, P.; Karttunen, P.; Lokkila, M.; Pekkanen, J.; Poellaenen, J.; Tarvainen, A.-M.; Toropainen, V.; Kosunen, P.; Pere, T.

2010-08-01

The construction of the ONKALO access tunnel started in September 2004 at Olkiluoto. Most of the investigations related to the construction of the access tunnel aim to ensure successful excavations, reinforcement and sealing. Pilot holes are drillholes, which are core drilled along the tunnel profile. The length of the pilot holes typically varies from several tens of metres to a couple of hundred metres. The pilot holes are aimed to confirm the quality of the rock mass for tunnel construction, and in particular to identify water conductive fractured zones and to provide information that could result in modifications of the existing construction plans. The pilot hole ONK-PH10 was drilled from chainage 3459 to chainage 3639 in March 2009. The length of the hole is 180.00 metres. The drilling was done as orientated core drilling. The deviation of the drillhole was measured during and after the drilling phase. Electric conductivity was measured from the collected returning water samples. Logging of the core samples included the following parameters: lithology, foliation, fracturing, fracture frequency, RQD, fractured zones, core loss, and weathering. The rock mechanical logging was based on Q-classification. The test to determine rock strength and deformation were made with Rock Tester -equipment. Water conductivity of the fractures or fractured zones was measured by Posiva Flow Log equipment. The measurements were done in two phases. During flow measurements also grounding resistance electric conductivity and temperature were measured. In flow logging test, sections of 0.5 m with increments of 0.1 m were used. Water loss measurements were conducted in the hole section 3.70-180.00 m dhd. Geophysical logging and optical imaging of the pilot hole included the fieldwork of all surveys, the integration of the data as well as interpretation of the acoustic and drillhole radar data. One of the objectives of the geochemical study was to get information of the composition of

Advanced Biotelemetry Systems for Space Life Sciences: PH Telemetry

Science.gov (United States)

Hines, John W.; Somps, Chris; Ricks, Robert; Kim, Lynn; Connolly, John P. (Technical Monitor)

1995-01-01

The SENSORS 2000! (S2K!) program at NASA's Ames Research Center is currently developing a biotelemetry system for monitoring pH and temperature in unrestrained subjects. This activity is part of a broader scope effort to provide an Advanced Biotelemetry System (ABTS) for use in future space life sciences research. Many anticipated research endeavors will require biomedical and biochemical sensors and related instrumentation to make continuous inflight measurements in a variable-gravity environment. Since crew time is limited, automated data acquisition, data processing, data storage, and subject health monitoring are required. An automated biochemical and physiological data acquisition system based on non invasive or implantable biotelemetry technology will meet these requirements. The ABTS will ultimately acquire a variety of physiological measurands including temperature, biopotentials (e.g. ECG, EEG, EMG, EOG), blood pressure, flow and dimensions, as well as chemical and biological parameters including pH. Development activities are planned in evolutionary, leveraged steps. Near-term activities include 1) development of a dual channel pH/temperature telemetry system, and 2) development of a low bandwidth, 4-channel telemetry system, that measures temperature, heart rate, pressure, and pH. This abstract describes the pH/temperature telemeter.

Drilling and the associated borehole measurements of the pilot hole ONK-PH2

International Nuclear Information System (INIS)

Oehberg, A.; Aaltonen, I.; Kemppainen, K.; Mattila, J.; Heikkinen, E.; Lahti, M.; Pussinen, V.; Niemonen, J.; Paaso, N.; Rouhiainen, P.

2005-11-01

The construction of the ONKALO access tunnel started in September 2004 at Olkiluoto. Most of the investigations related to the construction of the access tunnel aim to ensure successful excavations, reinforcement and sealing. Pilot holes are boreholes, which are core drilled along the tunnel profile. The length of the pilot holes typically varies from several tens of metres to a couple of hundred metres. The pilot holes will mostly aim to confirm the quality of the rock mass for tunnel construction, and in particular at identifying water conductive fractured zones and at providing information that could result in modifications of the existing construction plans. The pilot hole ONK-PH2 was drilled in December 2004. The length of the borehole is about 122 metres. The aim during the drilling work was to orientate core samples as much as possible. The deviation of the borehole was measured during and after the drilling phase. Electric conductivity was measured from the collected returning water samples. Logging of the core samples included the following parameters: lithology, foliation, fracturing, fracture frequency, RQD, fractured zones, core loss and weathering. The rock mechanical logging was based on Q-classification. The tests to determine rock strength and deformation properties were made with a Rock Tester-equipment. Difference Flow method was used for the determination of hydraulic conductivity and hydraulic head in fractures and fractured zones in the borehole. The overlapping i.e. the detailed flow logging mode was used. The flow logging was performed with 0.5 m section length and with 0.1 m depth increments. Geophysical borehole logging and optical imaging surveys of the pilot hole PH2 included the field work of all the surveys, the integration of the data as well as interpretation of the acoustic and borehole radar data. One of the objectives of the geochemical study was to get information of composition of ONKALO's groundwater before the construction will

Drilling and the associated drillhole measurements of the pilot hole ONK-PH4

International Nuclear Information System (INIS)

Oehberg, A.; Heikkinen, E.; Hirvonen, H.; Kemppainen, K.; Majapuro, J.; Niemonen, J.; Poellaenen, J.; Rouhiainen, P.; Rautio, T.

2006-09-01

The construction of the ONKALO access tunnel started in September 2004 at Olkiluoto. Most of the investigations related to the construction of the access tunnel aim to ensure successful excavations, reinforcement and sealing. Pilot holes are drillholes, which are core drilled along the tunnel profile. The length of the pilot holes typically varies from several tens of metres to a couple of hundred metres. The pilot holes are mostly aimed to confirm the quality of the rock mass for tunnel construction, and in particular to identify water conductive fractured zones and to provide information that could result in modifications of the existing construction plans. The pilot hole ONK-PH4 was drilled in October 2005. The length of the hole is 96.01 metres. During the drilling work core samples were oriented as much as possible. The deviation of the hole was measured during and after the drilling phase. Electric conductivity was measured from the collected returning water samples. Geological logging of the core samples included the following parameters: lithology, foliation, fracturing, fracture frequency, RQD, fractured zones, core loss and weathering. The rock mechanical logging was based on Q-classification. The tests to determine rock strength and deformation properties were made with a Rock Tester-equipment. Difference Flow method was used for the determination of hydraulic conductivity in fractures and fractured zones in the hole. The overlapping i.e. the detailed flow logging mode was used. The flow logging was performed with 0.5 m section length and with 0.1 m depth increment. Water loss tests (Lugeon tests) were used to give background information for the grouting design. Geophysical logging and optical imaging of the pilot hole PH4 included the field work of all surveys, the integration of the data as well as interpretation of the acoustic and drillhole radar data. One of the objectives of the geochemical study was to get information of composition of ONKALO

Drilling and the associated borehole measurements of the pilot hole ONK-PH3

International Nuclear Information System (INIS)

Oehberg, A.; Heikkinen, E.; Hirvonen, H.; Kemppainen, K.; Majapuro, J.; Niemonen, J.; Poellaenen, J.; Rouhiainen, P.

2006-03-01

The construction of the ONKALO access tunnel started in September 2004 at Olkiluoto. Most of the investigations related to the construction of the access tunnel aim to ensure successful excavations, reinforcement and sealing. Pilot holes are boreholes, which are core drilled along the tunnel profile. The length of the pilot holes typically varies from several tens of metres to a couple of hundred metres. The pilot holes will mostly aim to confirm the quality of the rock mass for tunnel construction, and in particular at identifying water conductive fractured zones and at providing information that could result in modifications of the existing construction plans. The pilot hole ONK-PH3 was drilled in September 2005. The length of the borehole is 145.04 metres. The aim during the drilling work was to orientate core samples as much as possible. The deviation of the borehole was measured during and after the drilling phase. Electric conductivity was measured from the collected returning water samples. Logging of the core samples included the following parameters: lithology, foliation, fracturing, fracture frequency, RQD, fractured zones, core loss and weathering. The rock mechanical logging was based on Q-classification. The tests to determine rock strength and deformation properties were made with a Rock Tester-equipment. Difference Flow method was used for the determination of hydraulic conductivity in fractures and fractured zones in the borehole. The overlapping i.e. the detailed flow logging mode was used. The flow logging was performed with 0.5 m section length and with 0.1 m depth increments. Water loss tests (Lugeon tests) and a pressure build-up test were used to give background information for the grouting design. Geophysical borehole logging and optical imaging surveys of the pilot hole PH3 included the field work of all the surveys, the integration of the data as well as interpretation of the acoustic and borehole radar data. One of the objectives of the

Preparation of acridine orange-doped silica nanoparticles for pH measurement

International Nuclear Information System (INIS)

Liu, Jinshui; Zang, Lingjie; Wang, Yiru; Liu, Guoning

2014-01-01

Acridine orange was first encapsulated into silica shell via a facile reverse microemusion method to built core–shell fluorescent nanoparticles. The nanoparticles are all in spherical shape and have a narrow size distribution, and its application as a optical pH sensor has been demonstrated. This novel sensor is based on the pH-dependent fluorescence intensities of acridine orange in different pH value. The fluorescence intensity of acridine orange-doped silica nanoparticles was decreased by increasing pH value. Under optimum conditions, the changes of fluorescence intensity were proportional to the pH value in the range of 8.00–10.90. In addition, the sensor can be easily separated by centrifugation and adds no pollution to the environment compared to the free dyes. Furthermore, the effects of ionic strength and co-existing substances were proved to have little influence on the determination of pH. The sensor has been successfully applied to determine the pH of two artificial samples. Hence, the core–shell fluorescent nanoparticles show potential for practical application. -- Highlights: • Acridine orange was encapsulated into silica shell via a facile reverse microemusion method to built core–shell fluorescent nanoparticles. • The fluorescence intensity of acridine orange-doped silica nanoparticles was decreased by increasing pH value. • Its can be used as an optical pH sensor. • The sensor can be easily separated by centrifugation and adds no pollution to the environment compared to the free dyes. • The sensor has been successfully applied to determine the pH of artificial samples

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.

Umbilical Cord Blood pH in Intrapartum Hypoxia.

Science.gov (United States)

Perveen, Fouzia; Khan, Ayesha; Ali, Tahmina; Rabia, Syeda

2015-09-01

To determine the association of cord arterial blood pH with neonatal outcome in cases of intrapartum fetal hypoxia. Descriptive analytical study. Gynaecology Unit-II, Civil Hospital, Karachi, from September 2011 to November 2012. All singleton cephalic fetuses at term gestation were included in the study. Those with any anomaly, malpresentation, medical disorders, maternal age 7.25, neonatal outcome measures (healthy, NICU admission or neonatal death), color of liquor and mode of delivery recorded on predesigned proforma. Statistical analysis performed by SPSS 16 by using independent-t test or chi-square test and ANOVA test as needed. A total of 204 newborns were evaluated. The mean pH level was found to be significantly different (p=0.007) in two groups. The pH value 7.25 had significant association (p 7.25. Majority (63.6%) cases needed caesarean section as compared to 31.4% controls. There is a significant association of cord arterial blood pH at birth with neonatal outcome at pH 7.25; but below the level of pH 7.25 it is still inconclusive.

Critical assessment of the pH of children's soap.

Science.gov (United States)

Mendes, Bruna Rafaela; Shimabukuro, Danielle Midori; Uber, Marjorie; Abagge, Kerstin Taniguchi

2016-01-01

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

Final report on CCQM-K9.2 : subsequent key comparison on pH determination of phosphate buffer by Harned cell measurements

OpenAIRE

Spitzer, Petra; Giera, Janine; Fraga, Isabel Cristina Serta; Jakobsen, Pia Tonnes; Jensen, Hans D.; Hyllested, Peter; Karpov, Oleg; Kutovoy, Viatcheslav; Nakamura, Susumu; Vospelova, Alena; Zvezdina, Valentina

2008-01-01

CCQM-K9.2 was performed supplementary to the key comparison CCQM-K9 [1] on the pH determination of a phosphate buffer with nominal pH ~ 6.9 (at 25 °C). The sample composition was very similar in both comparisons. Only the source of the starting material used for sample preparation was different. The comparison was restricted to the use of the primary method for pH (Harned cell measurement) as defined in the IUPAC Recommendations [2]. The measurement temperatures were15 °C, 25 °C , 37...

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.

Reliability of measured data for pH sensor arrays with fault diagnosis and data fusion based on LabVIEW.

Science.gov (United States)

Liao, Yi-Hung; Chou, Jung-Chuan; Lin, Chin-Yi

2013-12-13

Fault diagnosis (FD) and data fusion (DF) technologies implemented in the LabVIEW program were used for a ruthenium dioxide pH sensor array. The purpose of the fault diagnosis and data fusion technologies is to increase the reliability of measured data. Data fusion is a very useful statistical method used for sensor arrays in many fields. Fault diagnosis is used to avoid sensor faults and to measure errors in the electrochemical measurement system, therefore, in this study, we use fault diagnosis to remove any faulty sensors in advance, and then proceed with data fusion in the sensor array. The average, self-adaptive and coefficient of variance data fusion methods are used in this study. The pH electrode is fabricated with ruthenium dioxide (RuO2) sensing membrane using a sputtering system to deposit it onto a silicon substrate, and eight RuO2 pH electrodes are fabricated to form a sensor array for this study.

Reliability of Measured Data for pH Sensor Arrays with Fault Diagnosis and Data Fusion Based on LabVIEW

Directory of Open Access Journals (Sweden)

Yi-Hung Liao

2013-12-01

Full Text Available Fault diagnosis (FD and data fusion (DF technologies implemented in the LabVIEW program were used for a ruthenium dioxide pH sensor array. The purpose of the fault diagnosis and data fusion technologies is to increase the reliability of measured data. Data fusion is a very useful statistical method used for sensor arrays in many fields. Fault diagnosis is used to avoid sensor faults and to measure errors in the electrochemical measurement system, therefore, in this study, we use fault diagnosis to remove any faulty sensors in advance, and then proceed with data fusion in the sensor array. The average, self-adaptive and coefficient of variance data fusion methods are used in this study. The pH electrode is fabricated with ruthenium dioxide (RuO2 sensing membrane using a sputtering system to deposit it onto a silicon substrate, and eight RuO2 pH electrodes are fabricated to form a sensor array for this study.

Drilling and the associated drillhole measurements of the pilot hole ONK-PH8

International Nuclear Information System (INIS)

Karttunen, P.; Poellaenen, J.; Rautio, T.; Tarvainen, A.-M.; Lamminmaeki, T.; Kemppainen, K.; Kosunen, P.; Lampinen, H.

2009-02-01

The construction of the ONKALO access tunnel started in September 2004 at Olkiluoto. Most of the investigations related to the construction of the access tunnel aim to ensure successful excavations, reinforcement and sealing. Pilot holes are drillholes, which are core drilled along the tunnel profile. The length of the pilot holes typically varies from several tens of metres to a couple of hundred metres. The pilot holes are aimed to confirm the quality of the rock mass for tunnel construction, and in particular to identify water conductive fractured zones and to provide information that could result in modifications of the existing construction plans. The pilot hole ONK-PH8 was drilled from chainage 3116 to chainage 3266.29 in June- July 2008. The length of the hole is 150.29 metres. The aim during the drilling work was to orient core samples as much as possible. The deviation of the drillhole was measured during and after the drilling phase. Electric conductivity was measured from the collected returning water samples. Water conductivity of the fractures or fractured zones was measured by Posiva Flow Log equipment. The measurements were done in two phases. During flow measurements also grounding resistance, electric conductivity and temperature were measured. In flow logging test sections of 0.5 m and increments of 0.1 m were used. The water loss measurements failed. Logging of the core samples included the following parameters: lithology, foliation, fracturing, fracture frequency, RQD, fractured zones, core loss, and weathering. The rock mechanical logging was based on Q-classification. The test to determine rock strength and deformation were made with Rock Tester-equipment. Geophysical logging and optical imaging of the pilot hole included the fieldwork of all surveys, the integration of the data as well as interpretation of the acoustic and drillhole radar data. One of the objectives of the geochemical study was to get information of the composition of ONKALO

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)

Detection of Micrococcus Luteus Biofilm Formation in Microfluidic Environments by pH Measurement Using an Ion-Sensitive Field-Effect Transistor

Directory of Open Access Journals (Sweden)

Keiji Naruse

2013-02-01

Full Text Available Biofilm formation in microfluidic channels is difficult to detect because sampling volumes are too small for conventional turbidity measurements. To detect biofilm formation, we used an ion-sensitive field-effect transistor (ISFET measurement system to measure pH changes in small volumes of bacterial suspension. Cells of Micrococcus luteus (M. luteus were cultured in polystyrene (PS microtubes and polymethylmethacrylate (PMMA-based microfluidic channels laminated with polyvinylidene chloride. In microtubes, concentrations of bacteria and pH in the suspension were analyzed by measuring turbidity and using an ISFET sensor, respectively. In microfluidic channels containing 20 μL of bacterial suspension, we measured pH changes using the ISFET sensor and monitored biofilm formation using a microscope. We detected acidification and alkalinization phases of M. luteus from the ISFET sensor signals in both microtubes and microfluidic channels. In the alkalinization phase, after 2 day culture, dense biofilm formation was observed at the bottom of the microfluidic channels. In this study, we used an ISFET sensor to detect biofilm formation in clinical and industrial microfluidic environments by detecting alkalinization of the culture medium.

Detection of Micrococcus luteus biofilm formation in microfluidic environments by pH measurement using an ion-sensitive field-effect transistor.

Science.gov (United States)

Matsuura, Koji; Asano, Yuka; Yamada, Akira; Naruse, Keiji

2013-02-18

Biofilm formation in microfluidic channels is difficult to detect because sampling volumes are too small for conventional turbidity measurements. To detect biofilm formation, we used an ion-sensitive field-effect transistor (ISFET) measurement system to measure pH changes in small volumes of bacterial suspension. Cells of Micrococcus luteus (M. luteus) were cultured in polystyrene (PS) microtubes and polymethylmethacrylate (PMMA)-based microfluidic channels laminated with polyvinylidene chloride. In microtubes, concentrations of bacteria and pH in the suspension were analyzed by measuring turbidity and using an ISFET sensor, respectively. In microfluidic channels containing 20 μL of bacterial suspension, we measured pH changes using the ISFET sensor and monitored biofilm formation using a microscope. We detected acidification and alkalinization phases of M. luteus from the ISFET sensor signals in both microtubes and microfluidic channels. In the alkalinization phase, after 2 day culture, dense biofilm formation was observed at the bottom of the microfluidic channels. In this study, we used an ISFET sensor to detect biofilm formation in clinical and industrial microfluidic environments by detecting alkalinization of the culture medium. 

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 ...

DİŞ PLAĞINDA pH ÖLÇÜM YÖNTEMLERİ-DENTAL PLAQUE pH MEASUREMENTS

OpenAIRE

Koparal, Ece; Eronat, Cemal

2013-01-01

ÖzetBir substraün yenmesinden sonra diş üzerindeki plakta meydana gelen pH değişikliklerinin saptanmasına dayanan plak pH'ı ölçüm çalışmaları üç yöntemle yapılabilmektedir. İn vitro plak pH ölçümünde, diş üzerinden plak örnekleri alınarak ağız boşluğunun dışında ölçüm gerçekleştirilmektedir. İn vivo plak pH'ı ölçümünde ise telemetri ve yüzey duyarlı elektrot ile plağa dokundurularak ağız içinde ölçümler yapılmaktadır.Anahtar sözcükler: Dental plak, pH, plak örnekleme yöntemi, yüzey ...

Drilling and the associated drillhole measurements of the pilot hole ONK-PH7

International Nuclear Information System (INIS)

Oehberg, A.; Kemppainen, K.; Lampinen, H.; Niemonen, J.; Poelloenen, J.; Rouhiainen, P.; Rautio, T.; Tarvainen, A.-M.

2007-12-01

The construction of the ONKALO access tunnel started in September 2004 at Olkiluoto. Most of the investigations related to the construction of the access tunnel aim to ensure successful excavations, reinforcement and sealing. Pilot holes are drillholes, which are core drilled along the tunnel profile. The length of the pilot holes typically varies from several tens of metres to a couple of hundred metres. The pilot holes are aimed to confirm the quality of the rock mass for tunnel construction, and in particular to identify water conductive fractured zones and to provide information that could result in modifications of the existing construction plans. The pilot hole ONK-PH7 was drilled from chainage 1880 to chainage 1980.31 in February 2007. The length of the hole is 100.31 m. The aim during the drilling work was to orient core samples as much as possible. The deviation of the drillhole was measured during and after the drilling phase. Electric conductivity was measured from the collected returning water samples. Logging of the core samples included the following parameters: lithology, foliation, fracturing, fracture frequency, RQD, fractured zones, core loss and weathering. The rock mechanical logging was based on Q-classification. The tests to determine rock strength and deformation properties were made with a Rock Tester-equipment. Difference Flow method was used for the determination of hydraulic conductivity in fractures and fractured zones in the drillhole. The overlapping i.e. the detailed flow logging mode was used. Besides flow logging Single Point Resistance (SPR), Electric Conductivity (EC) and temperature of the drillhole water were also measured. The flow logging was performed with 0.5 m section length and with 0.1 m depth increment. Water loss measurements were conducted between the hole depth of 1.18 m and the hole bottom. Geophysical logging and optical imaging of the pilot hole included the fieldwork of all surveys, the integration of the data as

Sensitivities of Key Parameters in the Preparation of Silver/Silver Chloride Electrodes Used in Harned Cell Measurements of pH

Directory of Open Access Journals (Sweden)

Richard J. C. Brown

2011-08-01

Full Text Available A questionnaire was completed by fourteen world leading national metrology institutes to study the influence of several variables in the preparation of Ag/AgCl electrodes on the accuracy of Harned cell measurements of pH. The performance of each institute in the last decade has been assessed based on their results in eight key comparisons, organized by the Bureau International des Poids et Measures Consultative Committee for Amount of Substance, involving the measurement of pH of phosphate, phthalate, carbonate, borate and tetroxalate buffer solutions. The performance of each laboratory has been correlated to the results of the questionnaire to determine the critical parameters in the preparation of Ag/AgCl electrodes and their sensitivities with respect to the accuracy of pH measurement. This study reveals that the parameters most closely correlated to performance in comparisons are area of electrode wire exposed to the electrolyte, diameter and porosity of the Ag sphere prior to anodisation, amount of Ag converted to AgCl during anodisation, stability times employed for electrodes to reach equilibrium in solution prior to measurement, electrode rejection criteria employed and purity of reagents.

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.

Use of stream water pH and specific conductance measurements to identify ground water discharges of fly ash leachate

International Nuclear Information System (INIS)

Price, R.M.

1992-01-01

Low pH and high specific conductance are typical chemical characteristics of coal fly ash leachate. Measurements of these parameters in streams adjacent to a fly ash facility were used to identify areas of ground water discharge into the streams. In-situ specific conductance and pH were determined at approximately 50 surface water stations from on-site and off-site streams. The results of the in-situ determinations were used to select twelve surface water stations for more detailed chemical analyses. The chemical character of the stream water affected by ground water discharges was similar to the water quality of sedimentation ponds which received drainage from the fly ash embankment. The results indicated that in-situ measurements of indicator parameters such as pH and specific conductance can be used as a screening method for identifying surface water quality impacts at fly ash facilities

Residual stress measurements via neutron diffraction of additive manufactured stainless steel 17-4 PH.

Science.gov (United States)

Masoomi, Mohammad; Shamsaei, Nima; Winholtz, Robert A; Milner, Justin L; Gnäupel-Herold, Thomas; Elwany, Alaa; Mahmoudi, Mohamad; Thompson, Scott M

2017-08-01

Neutron diffraction was employed to measure internal residual stresses at various locations along stainless steel (SS) 17-4 PH specimens additively manufactured via laser-powder bed fusion (L-PBF). Of these specimens, two were rods (diameter=8 mm, length=80 mm) built vertically upward and one a parallelepiped (8×80×9 mm 3 ) built with its longest edge parallel to ground. One rod and the parallelepiped were left in their as-built condition, while the other rod was heat treated. Data presented provide insight into the microstructural characteristics of typical L-PBF SS 17-4 PH specimens and their dependence on build orientation and post-processing procedures such as heat treatment. Data have been deposited in the Data in Brief Dataverse repository (doi:10.7910/DVN/T41S3V).

Residual stress measurements via neutron diffraction of additive manufactured stainless steel 17-4 PH

Directory of Open Access Journals (Sweden)

Mohammad Masoomi

2017-08-01

Full Text Available Neutron diffraction was employed to measure internal residual stresses at various locations along stainless steel (SS 17-4 PH specimens additively manufactured via laser-powder bed fusion (L-PBF. Of these specimens, two were rods (diameter=8 mm, length=80 mm built vertically upward and one a parallelepiped (8×80×9 mm3 built with its longest edge parallel to ground. One rod and the parallelepiped were left in their as-built condition, while the other rod was heat treated. Data presented provide insight into the microstructural characteristics of typical L-PBF SS 17-4 PH specimens and their dependence on build orientation and post-processing procedures such as heat treatment. Data have been deposited in the Data in Brief Dataverse repository (doi:10.7910/DVN/T41S3V.

Chapter A6. Section 6.4. pH

Science.gov (United States)

Wilde, Franceska D.; Busenberg, Eurybiades; Radtke, Dean B.

2006-01-01

Measurement of pH is critical to the understanding of the viability and vulnerability of environmental waters and is considered a master variable in determining the aqueous geochemistry of an aqueous system. pH is a measure that represents the hydrogen-ion concentration (activity) of a solution. This section of the National Field Manual (NFM) describes U.S. Geological Survey (USGS) guidance and protocols for measurement of pH in ground and surface waters.

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.

KEY COMPARISON: Final report on CCQM-K9.2: Subsequent key comparison on pH determination of phosphate buffer by Harned cell measurements

Science.gov (United States)

Spitzer, Petra; Giera, Janine; Fraga, Isabel C.; Tønnes Jakobsen, Pia; Jensen, Hans D.; Hyllested, Peter; Karpov, Oleg; Kutovoy, Viatcheslav; Nakamura, Susumu; Vospelova, Alena; Zvezdina, Valentina

2008-01-01

CCQM-K9.2 was performed supplementary to the key comparison CCQM-K9 on the pH determination of a phosphate buffer with nominal pH ~ 6.9 (at 25 °C). The sample composition was very similar in both comparisons. Only the source of the starting material used for sample preparation was different. The comparison was restricted to the use of the primary method for pH (Harned cell measurement) as defined in the IUPAC Recommendations [2]. The measurement temperatures were 15 °C, 25 °C, 37 °C. CCQM-K9.2, CCQM-K.9 and the first supplementary comparison CCQM-K9.1 [5] are activities of the Electrochemical Working Group (EAWG) of the CCQM. All three comparisons were coordinated by the PTB, Germany. The Danish Primary Laboratory (DPL) successfully took part in the CCQM-K9. Meanwhile the primary set-up for pH in Denmark moved from DPL affiliated to Radiometer Medical to DFM, Denmark. The subsequent comparison allows assessing the degree of equivalence for the measurement of pH at DFM after the move. Due to the interest of other laboratories in demonstrating their progress in pH measurements on the primary level the CCQM-K9.2 supplementary comparison was extended to other participants than DFM, namely NMIJ, VNIIFTRI, INMETRO and CMI. The reported quantity for CCQM-K9.2 was not the pH of the sample but the acidity function at zero chloride molality (see chapter 12). To calculate the pH value from the acidity function it is necessary to know the ionic strength of the sample buffer solution, which was undisclosed by the coordinator. With the exception of the Czech Metrology Institute, CMI, good agreement in the determined acidity function is found between the participants. The results reported by DFM and by PTB agree within their measurement uncertainty at all measurement temperatures. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report

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.

How to measure PhD. students' conceptions of academic writing - and are they related to well-being?

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Kirsti Lonka

2014-02-01

Full Text Available This study investigated PhD students’ conceptions of writing and how they saw themselves as writers. The Writing Process Questionnaire was created to analyse PhD students’ ideas of academic writing. In addition, it was of interest, what the relation between conceptions of writing and the PhD students’ well-being was. The participants were 669 PhD students from a major Finnish university who volunteered to fill in a questionnaire. The present study covered scales for measuring six distinct theoretical constructs that were created by forming sum variables of 26 questions: Blocks, Procrastination, Perfectionism, Innate ability, Knowledge transforming, and Productivity. Confirmatory factor analysis (CFA was used to verify the six-dimension construct. Exhaustion, stress, anxiety and lack of interest all correlated positively with Blocks, Procrastination, and Perfectionism, and negatively with Productivity. Confirmatory factor analysis conducted by LISREL confirmed the six-factor structure of the writing scale. In conclusion, there is good evidence that the questionnaire is a reliable and valid tool, and it captures some essential aspectsof academic writing process and its emotional dimensions.

Noninvasive model including right ventricular speckle tracking for the evaluation of pulmonary hypertension.

Science.gov (United States)

Mahran, Yossra; Schueler, Robert; Weber, Marcel; Pizarro, Carmen; Nickenig, Georg; Skowasch, Dirk; Hammerstingl, Christoph

2016-08-26

To find parameters from transthorathic echocardiography (TTE) including speckle-tracking (ST) analysis of the right ventricle (RV) to identify precapillary pulmonary hypertension (PH). Forty-four patients with suspected PH undergoing right heart catheterization (RHC) were consecutively included (mean age 63.1 ± 14 years, 61% male gender). All patients underwent standardized TTE including ST analysis of the RV. Based on the subsequent TTE-derived measurements, the presence of PH was assessed: Left ventricular ejection fraction (LVEF) was calculated by Simpsons rule from 4Ch. Systolic pulmonary artery pressure (sPAP) was assessed with continuous wave Doppler of systolic tricuspid regurgitant velocity and regarded raised with values ≥ 30 mmHg as a surrogate parameter for RA pressure. A concomitantly elevated PCWP was considered a means to discriminate between the precapillary and postcapillary form of PH. PCWP was considered elevated when the E/e' ratio was > 12 as a surrogate for LV diastolic pressure. E/e' ratio was measured by gauging systolic and diastolic velocities of the lateral and septal mitral valve annulus using TDI mode. The results were then averaged with conventional measurement of mitral valve inflow. Furthermore, functional testing with six minutes walking distance (6MWD), ECG-RV stress signs, NT pro-BNP and other laboratory values were assessed. PH was confirmed in 34 patients (precapillary PH, n = 15, postcapillary PH, n = 19). TTE showed significant differences in E/e' ratio (precapillary PH: 12.3 ± 4.4, postcapillary PH: 17.3 ± 10.3, no PH: 12.1 ± 4.5, P = 0.02), LV volumes (ESV: 25.0 ± 15.0 mL, 49.9 ± 29.5 mL, 32.2 ± 13.6 mL, P = 0.027; EDV: 73.6 ± 24.0 mL, 110.6 ± 31.8 mL, 87.8 ± 33.0 mL, P = 0.021) and systolic pulmonary arterial pressure (sPAP: 61.2 ± 22.3 mmHg, 53.6 ± 20.1 mmHg, 31.2 ± 24.6 mmHg, P = 0.001). STRV analysis showed significant differences for apical RV longitudinal strain (RVAS: -7.5% ± 5.6%, -13.3% ± 4.3%, -14

Dual-lifetime referencing (DLR: a powerful method for on-line measurement of internal pH in carrier-bound immobilized biocatalysts

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Boniello Caterina

2012-03-01

conditions of continuous measurement. During hydrolysis of cephalosporin C by the immobilizate in a stirred reactor with bulk pH maintained at 8.0, the intraparticle pH dropped initially by about 1 pH unit and gradually returned to the bulk pH, reflecting the depletion of substrate from solution. These results support measurement of intraparticle pH as a potential analytical processing tool for proton-forming/consuming biotransformations catalyzed by carrier-bound immobilized enzymes. Conclusions Fluorescein and Ru(dpp constitute a useful pair of luminophores in by DLR-based intraparticle pH monitoring. The pH range accessible by the chosen DLR system overlaps favorably with the pH ranges at which enzymes are optimally active and stable. DLR removes the restriction of working with static immobilized enzyme particles, enabling suspensions of particles to be characterized also. The pH gradient developed between particle and bulk liquid during reaction steady state is an important carrier selection parameter for enzyme immobilization and optimization of biocatalytic conversion processes. Determination of this parameter was rendered possible by the presented DLR method.

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

Drilling and associated drillhole measurements of the pilot hole ONK-PH13

International Nuclear Information System (INIS)

Tarvainen, A.-M.; Toropainen, V.; Pekkanen, J.; Poellaenen, J.; Kosunen, P.; Lahti, M.; Pere, T.; Aalto, P.

2011-04-01

. Groundwater samples were not collected due to too low inflow to the drillhole. Geophysical surveys included natural gamma radiation, gamma-gamma density, magnetic susceptibility, Wenner resistivity, short and long normal resistivity, single point resistance, drillhole radar and full waveform sonic measurements as well as optical and acoustic imaging. The results were joined with the available geological data received from Posiva. A group of geoscientists produced an integrated interpretation based on the investigation results of ONK-PH13. In single-hole interpretation the objective is to identify and describe the general characteristics of major rock units and possible deformation zones within a drillhole. A single-hole interpretation involves integrated interpretation of the data from the geological mapping, geophysical logging as well as hydrogeological investigations. The method is regarded useful for integrated and detailed modelling for the use of the RSC (Rock Suitability Criteria) program. (orig.)

Measurement of pH, alkalinity and acidity in ultra-soft waters

African Journals Online (AJOL)

drinie

2001-10-04

Oct 4, 2001 ... A blend composed of the raw water, sodium chloride (to increase conductivity), and standard bicarbonate (to increase buffering capacity) was titrated with standard strong acid in two pH regions: 6.3 pH < 4.0. In both methods, total alkalinity was determined using the latter set of points, ...

Combination of On-line pH and Oxygen Transfer Rate Measurement in Shake Flasks by Fiber Optical Technique and Respiration Activity MOnitoring System (RAMOS

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Jochen Büchs

2007-12-01

Full Text Available Shake flasks are commonly used for process development in biotechnologyindustry. For this purpose a lot of information is required from the growth conditions duringthe fermentation experiments. Therefore, Anderlei et al. developed the RAMOS technology[1, 2], which proviedes on-line oxygen and carbondioxide transfer rates in shake flasks.Besides oxygen consumption, the pH in the medium also plays an important role for thesuccessful cultivation of micro-organisms and for process development. For online pHmeasurement fiber optical methods based on fluorophores are available. Here a combinationof the on-line Oxygen Transfer Rate (OTR measurements in the RAMOS device with anon-line, fiber optical pH measurement is presented. To demonstrate the application of thecombined measurement techniques, Escherichia coli cultivations were performed and on-line pH measurements were compared with off-line samples. The combination of on-lineOTR and pH measurements gives a lot of information about the cultivation and, therefore, itis a powerful technique for monitoring shake flask experiments as well as for processdevelopment.

Electrochemiluminescent pH sensor measured by the emission potential of TiO2 nanocrystals and its biosensing application.

Science.gov (United States)

Liu, Xuan; Wang, Nianyue; Zhao, Wei; Jiang, Hui

2015-02-01

This work reports for the first time a potential-based nano-electrochemiluminescent (ECL) pH sensor, using anatase TiO2 nanocrystals (NCs) as the ECL probe. The first ECL peak potential of the TiO2 NCs shifted negatively with increasing pH, showing a linear range from -0.47 V (vs Ag/AgCl) at pH 3 to -1.06 V at pH 10. This phenomenon was attributed to the absorption of 'potential-determining ions' of OH(-) on the surface of TiO2 NCs, leading to larger impedance of the electron injection. Other common 'potential-determining ions', such as phosphate, induced a slight potential shift of 0.03 V at a concentration of 0.1 M. Using urease as an enzyme model, a urea biosensor was developed by the simultaneous modification of urease and TiO2 NCs on indium-tin oxide (ITO) electrodes. The biosensor, measured on the basis of the pH increase caused by the enzyme catalysis reaction, had a linear range of 0.01-2.0 mM, with a potential shift of 0.175 V. The as-prepared pH sensor, which has simple construction procedures and acceptable sensitivity and selectivity, may provide new avenues for the construction of ECL bioanalytical methodologies. Copyright © 2014 John Wiley & Sons, Ltd.

Prevalence of oral lesions and measurement of salivary pH in the different trimesters of pregnancy.

Science.gov (United States)

Jain, Kanu; Kaur, Harshaminder

2015-01-01

Oral changes observed during pregnancy have been studied for many years, but their magnitude and frequency have not been stressed upon. This study was undertaken to assess the prevalence of oral lesions during different trimesters of pregnancy and their correlation with salivary pH change. The gingival, simplified oral hygiene, community periodontal and decayed-missing-filled teeth indices were used to assess a total of 120 pregnant women (40 in each trimester group) and 40 nonpregnant women (control group). Salivary pH was measured using a digital pH meter. Presence of any oral lesions was determined via oral examination. Scores for all indices increased while salivary pH decreased from the control group to the first trimester group, through to the third. Oral lesions were seen in 44.2% of pregnant women. Lesions were seen in 27.5%, 52.5% and 52.5% of women in the first, second and third trimesters, respectively. The percentage of pregnant women with one oral lesion was highest in the second trimester (47.5%), whereas the third trimester had the highest prevalence (17.5%) of two concurrent oral lesions. The incidence of fissured tongue was highest in the first trimester group, and that of gingival enlargement was highest in the third trimester group. In the second trimester group, there was an almost equal incidence of fissured tongue and gingival/mucosal enlargement. Most changes in oral tissues during pregnancy can be avoided with good oral hygiene. Salivary pH could be used to assess the prevalence of oral lesions in the different trimesters of pregnancy.

Optoelectronic pH Meter: Further Details

Science.gov (United States)

Jeevarajan, Antony S.; Anderson, Mejody M.; Macatangay, Ariel V.

2009-01-01

A collection of documents provides further detailed information about an optoelectronic instrument that measures the pH of an aqueous cell-culture medium to within 0.1 unit in the range from 6.5 to 7.5. The instrument at an earlier stage of development was reported in Optoelectronic Instrument Monitors pH in a Culture Medium (MSC-23107), NASA Tech Briefs, Vol. 28, No. 9 (September 2004), page 4a. To recapitulate: The instrument includes a quartz cuvette through which the medium flows as it is circulated through a bioreactor. The medium contains some phenol red, which is an organic pH-indicator dye. The cuvette sits between a light source and a photodetector. [The light source in the earlier version comprised red (625 nm) and green (558 nm) light-emitting diodes (LEDs); the light source in the present version comprises a single green- (560 nm)-or-red (623 nm) LED.] The red and green are repeatedly flashed in alternation. The responses of the photodiode to the green and red are processed electronically to obtain the ratio between the amounts of green and red light transmitted through the medium. The optical absorbance of the phenol red in the green light varies as a known function of pH. Hence, the pH of the medium can be calculated from the aforesaid ratio.

Initial steps in defining the environment of the prepuce of the bull by measuring pH and temperature.

Science.gov (United States)

Koziol, J H; Fraser, N S; Passler, T; Wolfe, D F

2017-12-01

To determine the baseline pH and temperature of the preputial cavity of bulls. We enrolled 55 bulls ranging in age from 15 to 84 months. The preputial temperature and pH were measured by insertion of temperature and pH probes, respectively, into the preputial orifice prior to routine breeding soundness examinations. Information was obtained from owners regarding the diet of each bull and categorised as one of three categories: forage only, grain supplemented or silage supplemented. The average temperature of the prepuce was 37.81°C ± 1.76 and the median pH of the prepuce was 8.45 (6.35-9.46). Preputial temperatures of the bull weakly correlated with ambient temperatures (r s  = -0.29, P = 0.028). The preputial pH of silage-fed bulls was significantly lower than that of bulls fed forage only (P = 0.025) or grain-supplemented diets (P = 0.002). The median preputial pH of bulls fed a silage-based diet was 7.6 (6.3-8.9) compared with a median pH 8.7 (7.8-9.1) for bulls fed forage-based diets or a median of 8.5 (7.7-9.4) for those given grain-supplemented diets. Diet and ambient temperature can, respectively, affect pH and the temperature in the prepuce. Further studies to describe and understand the microbiota of the prepuce and penis may assist in developing treatments for diseases of the genital tract in bulls. © 2017 Australian Veterinary Association.

Salivary pH changes in children after industrialized fruit juice consumption

OpenAIRE

Juliana Yassue Barbosa da SILVA; João Armando BRANCHER; João Gilberto DUDA; Estela Maris LOSSO

2008-01-01

Introduction: The children presented dental erosion and caries in early infancy that were associated to a rich diet in sugars, including the frequent ingestion of industrialized fruit juice (conditioned in boxes).The drink ingestion with pH lower than 5.5 can cause teeth erosion mainly if it is associated with frequent and prolonged teeth contact.The natural protection of teeth is the saliva through its buffering capacity.Objective: Measure the children salivary pH before and after the grape ...

Effect of pH grade on polymer-gel dosimeter and its brachytherapy application

International Nuclear Information System (INIS)

Spevacek, V.; Hrbacek, J.; Dvorak, P.; Cechak, T.; Novotny, J.

2003-01-01

To evaluate impact of pH grade on characteristics of polymer-gel dosimeter and its application in dose distribution verification in brachytherapy. A polymer-gel dosimeter based on radiation induced polymerization and crosslinking of acrylic monomers (acrylic acid, N,N' methylen-bis-acrylamide) was investigated with respect to its pH grade. pH grade of a dosimeter was varied by concentration of natrium hydroxide. Afterwards, dosimeter was split into several samples which were uniformly irradiated with Co-60 gamma rays. The range of doses applied was usually from 0 to 50 Gy with the main interest in region up to 20 Gy. Evaluation of dosimeter dose response was performed using MRI (T2). Dose response curves obtained were evaluated with respect to pH grade as a parameter. In parallel, there was studied temperature resistance (melting temperature) of gels with various pH grade. pH grade modified polymer-gel dosimeter was then used to compare dose distribution calculated with brachytherapy treatment planning system for simple irradiation geometry with Ir-192 HDR source. Additionaly, Monte Carlo calculated data were also included in the brachytherapy study. There was observed effect of pH grade on dose-response curve parameters (slope of linear fit, background response, linear range and maximum measurable dose). In general, the lower pH grade the higher sensitivity. Another positive effect of decreased pH grade is significantly higher maximum measurable dose. Maximum melting temperature of a gel was observed with pH grade between 3.5 and 4. For both higher and lower pH grades the melting temperature was lower. Using pH modified polymer-gel dosimeter simple brachytherapy dose distribution was measured and compared with calculated and Monte Carlo simulated data. There was observed strong dependence of dose-response relationship on pH grade of polymer-gel dosimeter resulting in significant improvement of dosimeter characteristics, namely sensitivity, applicable range of

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.

Continuous measurement of electrical characteristics in plants. 3. Shokubutsu seitai no denki tokusei sokuteiho. 3. ; Suikoeki pH chosei heno tekiyo

Energy Technology Data Exchange (ETDEWEB)

Sekiyama, T; Haniyu, H; Saiki, H

1989-09-01

Controlling pH of nutrient solution and keeping the other conditions unchanged, measurements of variation in electric potential difference between leaf and hypocotyl of a bush bean plant was performed for about seven days. Silver electrodes 0.3mm in diameter were glued on the surface of the plant using conductive paste prepared by dissolving gelatine in Ringel {prime} s solution. The results obtained are summarized as follws: first, when pH of the solution is suddenly increased or decreased, the potential of leave becomes high or low with respect to that of hypocotyl respectively; second, the variation in potential difference between them is affected by the rate at which pH of the solution is adjusted, although the total variation of pH is controlled to be the same, and in particular by mild adjustment (0.02 - 0.05pH/min) it is reduced to 1/2 - 1/4 of that produced by sudden change; third, abrupt change in pH of the solution cause to the plant the temporary suppression of its water absorption having a duration of 7 - 15 minutes. A short account is given of a non-contact type measurement of bioelectric potential performanced by making use of a Faraday {prime} s cage. 11 refs., 12 figs.

pH control and rapid mixing in spinning NMR samples

Science.gov (United States)

Yesinowski, James P.; Sunberg, Richard J.; Benedict, James J.

An apparatus is described which permits the acquisition of NMR spectra from spinning 20-mm sample tubes while: (1) constantly monitoring the pH; (2) adding reagents to maintain constant pH (pH-statting); (3) efficiently mixing the added reagent. The apparatus was built to study the spontaneous precipitation of calcium phosphates from supersaturated solutions using 31P NMR. Other applications include the rapid determination of NMR titration curves, and the minimization of temperature gradients in large sample tubes. The apparatus was used to measure the 31P chemical shift titration of dilute phosphoric acid, which yielded accurate shifts for the three species of protonated orthophosphate ion. The bulk magnetic susceptibility of 85% H 3PO 4 relative to a dilute aqueous sample was also measured, and is shown to contribute significantly to chemical shift measurements.

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.

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

A genetically encoded ratiometric sensor to measure extracellular pH in microdomains bounded by basolateral membranes of epithelial cells.

Science.gov (United States)

Urra, Javier; Sandoval, Moisés; Cornejo, Isabel; Barros, L Felipe; Sepúlveda, Francisco V; Cid, L Pablo

2008-10-01

Extracellular pH, especially in relatively inaccessible microdomains between cells, affects transport membrane protein activity and might have an intercellular signaling role. We have developed a genetically encoded extracellular pH sensor capable of detecting pH changes in basolateral spaces of epithelial cells. It consists of a chimerical membrane protein displaying concatenated enhanced variants of cyan fluorescence protein (ECFP) and yellow fluorescence protein (EYFP) at the external aspect of the cell surface. The construct, termed pHCECSensor01, was targeted to basolateral membranes of Madin-Darby canine kidney (MDCK) cells by means of a sequence derived from the aquaporin AQP4. The fusion of pH-sensitive EYFP with pH-insensitive ECFP allows ratiometric pH measurements. The titration curve of pHCECSensor01 in vivo had a pK (a) value of 6.5 +/- 0.04. Only minor effects of extracellular chloride on pHCECSensor01 were observed around the physiological concentrations of this anion. In MDCK cells, the sensor was able to detect changes in pH secondary to H(+) efflux into the basolateral spaces elicited by an ammonium prepulse or lactate load. This genetically encoded sensor has the potential to serve as a noninvasive tool for monitoring changes in extracellular pH microdomains in epithelial and other tissues in vivo.

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...

Influence of pH on the localized corrosion of iron

International Nuclear Information System (INIS)

Webley, R.; Henry, R.

1986-06-01

The influence of pH on the pitting corrosion of iron in chloride and sulfate solutions was determined using two artificial pit apparatuses to obtain the pH near the surface of the pit bottom. A glass membrane electrode and an antimony electrode were used to measure pH in the two apparatuses. Using solutions of NaCl and Na 2 SO 4 at current densities of 0.5, 5.0, and 10 mA/cm 2 pH's in the range 5 to 6 were obtained with the first apparatus. The antimony probe did not measure pH accurately in solutions of 1 N NaCl and 1 N Na 2 SO 4 and had an error of approximately 2 pH units. A one-dimensional transport model was developed to predict pH variations around the pit mouth and inside the pit. The validity of this model was not verified due to the relative lack of precision with pH measurement techniques

Measures for Ph.D. Evaluation: The Recruitment Process

Science.gov (United States)

D'Agostino, Antonella; Fruzzetti, Stefania; Ghellini, Giulio; Neri, Laura

2011-01-01

In the last years the quality of Higher Education (HE) system and its evaluation have been key issues of the political and scientific debate on education policies all over Europe. In the wide landscape that involves the entire HE system we draw attention on the third level of its organization, i.e. the Ph.D. In particular, this paper discusses the…

Sorption of Sr, Co and Zn on illite: Batch experiments and modelling including Co in-diffusion measurements on compacted samples

Science.gov (United States)

Montoya, V.; Baeyens, B.; Glaus, M. A.; Kupcik, T.; Marques Fernandes, M.; Van Laer, L.; Bruggeman, C.; Maes, N.; Schäfer, T.

2018-02-01

Experimental investigations on the uptake of divalent cations (Sr, Co and Zn) onto illite (Illite du Puy, Le-Puy-en-Velay, France) were carried out by three different international research groups (Institute for Nuclear Waste Disposal, KIT (Germany), Group Waste & Disposal, SCK-CEN, (Belgium) and Laboratory for Waste Management, PSI (Switzerland)) in the framework of the European FP7 CatClay project. The dependence of solid-liquid distribution ratios (Rd values) on pH at trace metal conditions (sorption edges) and on the metal ion concentration (sorption isotherms) was determined in dilute suspensions of homo-ionic Na-illite (Na-IdP) under controlled N2 atmosphere. The experimental results were modelled using the 2 Site Protolysis Non Electrostatic Surface Complexation and Cation Exchange (2SPNE SC/CE) sorption model. The sorption of Sr depends strongly on ionic strength, while a rather weak pH dependence is observed in a pH range between 3 and 11. The data were modelled with cation exchange reactions, taking into account competition with H, K, Ca, Mg and Al, and surface complexation on weak amphotheric edge sites at higher pH values. The sorption of Co on Na-IdP, however, is strongly pH dependent. Cation exchange on the planar sites and surface complexation on strong and weak amphoteric edge sites were used to describe the Co sorption data. Rd values for Co derived from in-diffusion measurements on compacted Na-IdP samples (bulk-dry density of 1700 kg m-3) between pH 5.0 and 9.0 are in good agreement with the batch sorption data. The equivalence of both approaches to measure sorption was thus confirmed for the present test system. In addition, the results highlight the importance of both major and minor surface species for the diffusive transport behaviour of strongly sorbing metal cations. While surface complexes at the edge sites determine largely the Rd value, the diffusive flux may be governed by those species bound to the planar sites, even at low fractional

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.

Round robin test for define an accurate protocol to measure the pore fluid pH of low-pH cementitious materials

International Nuclear Information System (INIS)

Alonso, M.C.; Garcia Calvo, J.L.; Pettersson, S.; Puigdomenech, I.; Cunado, M.A.; Vuorio, M.; Weber, H.; Ueda, H.; Naito, M.; Walker, C.; Takeshi, Y.; Cau Dit Coumes, C.

2012-01-01

The present research belongs to an international project where several of the main nuclear waste management agencies have been involved. The main objective is the development of agreed procedures or protocols for measuring the pH value using low-pH cementitious products (LopHC). The Pore Fluid Expression (PFE) has been identified as reference method and Ex-situ Leaching methods (ELS) with two variants (filtering and without filtering the obtained suspension) have been identified as routine methods. Both methodologies are based on the extraction of the pore solution of the concrete before pH determination. The protocols employed were based on a broad literature review and in fitting the more critical parameters, such as the sample size, the carbonation affection, the leaching of cement hydrates during the measurement, etc. Moreover, the routine methods were validated with respect to the pore fluid expression results. It appears that the repeatability of the 3 pH measurement protocols is very good and that the results obtained with both ESL procedures agree well with the results given by the PFE technique in the case of low-pH cementitious materials and are acceptable in the case of cementitious materials with high pore fluid pH values, in that case some corrections considering the Ca content of the solution may be needed

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.

A genetically-encoded chloride and pH sensor for dissociating ion dynamics in the nervous system

OpenAIRE

Raimondo, Joseph V.; Joyce, Bradley; Kay, Louise; Schlagheck, Theresa; Newey, Sarah E.; Srinivas, Shankar; Akerman, Colin J.

2013-01-01

Within the nervous system, intracellular Cl− and pH regulate fundamental processes including cell proliferation, metabolism, synaptic transmission, and network excitability. Cl− and pH are often co-regulated, and network activity results in the movement of both Cl− and H+. Tools to accurately measure these ions are crucial for understanding their role under physiological and pathological conditions. Although genetically-encoded Cl− and pH sensors have been described previously, these either l...

Monitoring the Productivity of Coastal Systems Using PH ...

Science.gov (United States)

The impact of nutrient inputs to the eutrophication of coastal ecosystems has been one of the great themes of coastal ecology. There have been countless studies devoted to quantifying how human sources of nutrients, in particular nitrogen (N), effect coastal water bodies. These studies, which often measure in situ concentrations of nutrients, chlorophyll, and dissolved oxygen, are often spatially and/or temporally intensive and expensive. We provide evidence from experimental mesocosms, coupled with data from the water column of a well-mixed estuary, that pH can be a quick, inexpensive, and integrative measure of net ecosystem metabolism. In some cases, this approach is a more sensitive tracer of production than direct measurements of chlorophyll and carbon-14. Taken together, our data suggest that pH is a sensitive, but often overlooked, tool for monitoring estuarine production. This presentation will explore the potential utility of pH as an indicator of ecosystem productivity. Our data suggest that pH is a sensitive and potentially integrator of net ecosystem production. It should not be overlooked, that measuring pH is quick, easy, and inexpensive, further increasing its value as an analytical tool.

Determination of water pH using absorption-based optical sensors: evaluation of different calculation methods

Science.gov (United States)

Wang, Hongliang; Liu, Baohua; Ding, Zhongjun; Wang, Xiangxin

2017-02-01

Absorption-based optical sensors have been developed for the determination of water pH. In this paper, based on the preparation of a transparent sol-gel thin film with a phenol red (PR) indicator, several calculation methods, including simple linear regression analysis, quadratic regression analysis and dual-wavelength absorbance ratio analysis, were used to calculate water pH. Results of MSSRR show that dual-wavelength absorbance ratio analysis can improve the calculation accuracy of water pH in long-term measurement.

ORP and pH measurements to detect redox and acid-base anomalies from hydrothermal activity

Science.gov (United States)

Santana-Casiano, J. M.; González-Dávila, M.; Fraile-Nuez, E.

2017-12-01

The Tagoro submarine volcano is located 1.8 km south of the Island of El Hierro at 350 m depth and rises up to 88 m below sea level. It was erupting melting material for five months, from October 2011 to March 2012, changing drastically the physical-chemical properties of the water column in the area. After this eruption, the system evolved to a hydrothermal system. The character of both reduced and acid of the hydrothermal emissions in the Tagoro submarine volcano allowed us to detect anomalies related with changes in the chemical potential and the proton concentration using ORP and pH sensors, respectively. Tow-yos using a CTD-rosette with these two sensors provided the locations of the emissions plotting δ(ORP)/δt and ΔpH versus the latitude or longitude. The ORP sensor responds very quickly to the presence of reduced chemicals in the water column. Changes in potential are proportional to the amount of reduced chemical species present in the water. The magnitude of these changes are examined by the time derivative of ORP, δ(ORP)/δt. To detect changes in the pH, the mean pH for each depth at a reference station in an area not affected by the vent emission is subtracted from each point measured near the volcanic edifice, defining in this way ΔpH. Detailed surveys of the volcanic edifice were carried out between 2014 and 2016 using several CTD-pH-ORP tow-yo studies, localizing the ORP and pH changes, which were used to obtain surface maps of anomalies. Moreover, meridional tow-yos were used to calculate the amount of volcanic CO2 added to the water column. The inputs of CO2 along multiple sections combined with measurements of oceanic currents produced an estimated volcanic CO2 flux = 6.0 105 ± 1.1 105 kg d-1 which increases the acidity above the volcano by 20%. Sites like the Tagoro submarine volcano, in its degasification stage, provide an excellent opportunity to study the carbonate system in a high CO2 world, the volcanic contribution to the global

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...

Optical fiber pH sensors for high temperature water. Final report

International Nuclear Information System (INIS)

McCrae, D.; Saaski, E.

1994-11-01

The goal of this program was the development of an optical pH measurement system capable of operating in a high-temperature aqueous environment. This project built upon a dual-wavelength fiber optic sensing system previously developed by Research International which utilizes light-emitting diodes as light sources and provides remote absorption spectroscopy via a single bidirectional optical fiber. Suitable materials for constructing an optical pH sensing element were identified during the program. These included a sapphire/Ti/Pt/Au thin-film reflector, quartz and sapphire waveguides, a poly(benzimidazole) matrix, and an azo chromophore indicator. By a suitable combination of these design elements, it appears possible to optically measure pH in aqueous systems up to a temperature of about 150 degrees C. A pH sensing system capable of operating in high-purity, low-conductivity water was built using quasi-evanescent wave sensing techniques. The sensing element incorporated a novel, mixed cellulose/cellulose acetate waveguide to which an azo indicator was bound. Testing revealed that the system could reproducibly respond to pH changes arising from 1 ppm differences in the morpholine content of low-conductivity water without influencing the measurement. The sensing system was stable for 150 hrs at room temperature, and no loss or degradation of the pH-responsive optical indicator was seen in 160 hrs at 50 degrees C. However, the prototype polymer waveguide lost transparency at 1.7% per day during this same 50 degrees C test. Additional effort is warranted in the areas of water-compatible waveguides and evanescent-wave detection methods

Synergic effect of salivary pH baselines and low pH intakes on the force relaxation of orthodontic latex elastics.

Science.gov (United States)

Ajami, Shabnam; Farjood, Amin; Zare, Mahbubeh

2017-01-01

Latex elastics are still in common use due to their low cost and high flexibility to improve sagittal discrepancies or interdigitation of teeth. Mechanical properties of elastics are influenced by several environmental factors such as pH changes. This study evaluated similar latex elastics to define the influence of synergic effect of intermittent low pH and various baselines pH of saliva. Four groups of latex elastics (3-M Unitek, 3/16 inch) were tested ( n = 15 in each group). Two groups of elastics were immersed in two tanks of artificial saliva with different pH levels of 7 and 5, and two groups were immersed in two tanks of artificial saliva with intermittent drop of pH to 4. The force was measured when the elastics were stretched to 25 mm. These measurements were taken in 0, 4, 8, 12, 24, 36, and 48 h for each group. Repeated measures analysis of variance (RMANOVA) and post-hoc Tukey's test were used to assess the findings. The level of significance was 0.05%. The interaction between pH and time analyzed with RMANOVA showed no significant differences ( P > 0.05) except in 36 h ( P = 0.014). The Tukey's analysis showed that each comparison between any two groups did not indicate significant differences ( P > 0.05) except between Groups 1 and 3 and between Groups 2 and 3 ( P pH and force degradation in latex elastic band except in 36 h.

Effects of Iodide and Hydrogen Peroxide on Measuring High Temperature pH in Various Lithium Borate Buffer Solutions

Energy Technology Data Exchange (ETDEWEB)

Hwang, Jae Sik; Yun, Myung Hee; Yeon, Jei Won; Song, Kyu Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2008-10-15

In a reactor coolant system of nuclear power plants, the need for reliable high temperature pH electrodes has resulted from interests in the corrosion and corrosion product behaviors of the structural materials in a high temperature coolant system. In developing the electrodes for measuring the high temperature pH of aqueous solutions, it is necessary to note two major problems: the chemical stability of an electrode against other chemical impurities, and an electrode's integrity as the temperature and pressure are varied between operational extremes. Over the past decade Macdonald et al. and Danielson et al. have developed many ceramic membrane pH electrodes based on a yttrium stabilized zirconium oxide. However, there are still many experimental difficulties associated with the problems in obtaining electrochemical information across different pressure boundaries and against many kinds of chemical impurities caused by the radiolysis of water and the leakage of a fuel clad. In the present work, we investigated the effects of the environmental factors on a high temperature pH. The selected environmental factors are as follows: system pressure, and chemical species such as iodide and hydrogen peroxide ions.

Direct Measurement of pH in Individual Particles via Raman Microspectroscopy and Variation in Acidity with Relative Humidity.

Science.gov (United States)

Rindelaub, Joel D; Craig, Rebecca L; Nandy, Lucy; Bondy, Amy L; Dutcher, Cari S; Shepson, Paul B; Ault, Andrew P

2016-02-18

Atmospheric aerosol acidity is an important characteristic of aqueous particles, which has been linked to the formation of secondary organic aerosol by catalyzing reactions of oxidized organic compounds that have partitioned to the particle phase. However, aerosol acidity is difficult to measure and traditionally estimated using indirect methods or assumptions based on composition. Ongoing disagreements between experiments and thermodynamic models of particle acidity necessitate improved fundamental understanding of pH and ion behavior in high ionic strength atmospheric particles. Herein, Raman microspectroscopy was used to determine the pH of individual particles (H2SO4+MgSO4) based on sulfate and bisulfate concentrations determined from νs(SO4(2-)) and νs(HSO4(-)), the acid dissociation constant, and activity coefficients from extended Debye-Hückel calculations. Shifts in pH and peak positions of νs(SO4(2-)) and νs(HSO4(-)) were observed as a function of relative humidity. These results indicate the potential for direct spectroscopic determination of pH in individual particles and the need to improve fundamental understanding of ion behavior in atmospheric particles.

[Intraesophageal pH in children with suspected reflux].

Science.gov (United States)

Calva-Rodríguez, R; García-Aranda, J A; Bendimez-Cano, A; Estrada-Saavedra, R

1989-05-01

We study 22 children with clinical symptoms of gastroesophageal reflux. The main manifestations were: frequent vomiting, failure to thrive and repetitive pneumonia. In all of them we perform barium esophagogram (SEGD) with fluoroscopy, esophageal manometry (EM) and a four hours intraesophageal pH measurement. Thirteen of the twenty two children present a pathologic reflux (ERGE); in 16 we found SEGD that show reflux; three of them had an abnormal EM, the other 13 were normal. Seven patients showed alteration of the intraesophageal pH measurement. In conclusion the intraesophageal pH measurement in short period of time (4 hours) is a good method in the diagnosis of patients with ERGE.

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

CARINA data synthesis project: pH data scale unification and cruise adjustments

Science.gov (United States)

Velo, A.; Pérez, F. F.; Lin, X.; Key, R. M.; Tanhua, T.; de La Paz, M.; Olsen, A.; van Heuven, S.; Jutterström, S.; Ríos, A. F.

2010-05-01

Data on carbon and carbon-relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruise data sets in the Artic Mediterranean Seas (AMS), Atlantic Ocean and Southern Ocean have been retrieved and merged to a new database: CARINA (CARbon IN the Atlantic Ocean). These data have gone through rigorous quality control (QC) procedures to assure the highest possible quality and consistency. The data for most of the measured parameters in the CARINA database were objectively examined in order to quantify systematic differences in the reported values. Systematic biases found in the data have been corrected in the data products, three merged data files with measured, calculated and interpolated data for each of the three CARINA regions; AMS, Atlantic Ocean and Southern Ocean. Out of a total of 188 cruise entries in the CARINA database, 59 reported pH measured values. All reported pH data have been unified to the Sea-Water Scale (SWS) at 25 °C. Here we present details of the secondary QC of pH in the CARINA database and the scale unification to SWS at 25 °C. The pH scale has been converted for 36 cruises. Procedures of quality control, including crossover analysis between cruises and inversion analysis are described. Adjustments were applied to the pH values for 21 of the cruises in the CARINA dataset. With these adjustments the CARINA database is consistent both internally as well as with the GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s. Based on our analysis we estimate the internal consistency of the CARINA pH data to be 0.005 pH units. The CARINA data are now suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates, for ocean acidification assessment and for model validation.

Acid Rain, pH & Acidity: A Common Misinterpretation.

Science.gov (United States)

Clark, David B.; Thompson, Ronald E.

1989-01-01

Illustrates the basis for misleading statements about the relationship between pH and acid content in acid rain. Explains why pH cannot be used as a measure of acidity for rain or any other solution. Suggests that teachers present acidity and pH as two separate and distinct concepts. (RT)

Development of a fluorescence endoscopic system for pH mapping of gastric tissue

Science.gov (United States)

Rochon, Philippe; Mordon, Serge; Buys, Bruno; Dhelin, Guy; Lesage, Jean C.; Chopin, Claude

2003-10-01

Measurement of gastro intestinal intramucosal pH (pHim) has been recognized as an important factor in the detection of hypoxia induced dysfonctions. However, current pH measurements techniques are limited in terms of time and spatial resolutions. A major advance in accurate pH measurement was the development of the ratiometric fluorescent indicator dye, 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF). BCECF which pKa is in the physiological pH range is suitable for pH tissue measurements in vivo. This study aimed to develop and evaluate an endoscopic imaging system for real time pH measurements in the stomach in order to provide to ICU a new tool for gastro intestinal intramucosal pH (pHim) measurements. This fluorescence imaging technique should allow the temporal exploration of sequential events, particularly in ICU where the pHim provides a predictive information of the patient' status. The experimental evaluations of this new and innovative endoscopic fluorescence system confirms the accuracy of pH measurement using BCECF.

Stratum corneum hydration and skin surface pH in patients with atopic dermatitis.

Science.gov (United States)

Knor, Tanja; Meholjić-Fetahović, Ajša; Mehmedagić, Aida

2011-01-01

Atopic dermatitis (AD) is a chronically relapsing skin disease with genetic predisposition, which occurs most frequently in preschool children. It is considered that dryness and pruritus, which are always present in AD, are in correlation with degradation of the skin barrier function. Measurement of hydration and pH value of the stratum corneum is one of the noninvasive methods for evaluation of skin barrier function. The aim of the study was to assess skin barrier function by measuring stratum corneum hydration and skin surface pH of the skin with lesions, perilesional skin and uninvolved skin in AD patients, and skin in a healthy control group. Forty-two patients were included in the study: 21 young and adult AD patients and 21 age-matched healthy controls. Capacitance, which is correlated with hydration of stratum corneum and skin surface pH were measured on the forearm in the above areas by SM810/CM820/pH900 combined units (Courage AND Khazaka, Germany). The mean value of water capacitance measured in AD patients was 44.1 ± 11.6 AU (arbitrary units) on the lesions, 60.2 ± 12.4 AU on perilesional skin and 67.2 ± 8.8 AU on uninvolved skin. In healthy controls, the mean value was 74.1 ± 9.2 AU. The mean pH value measured in AD patients was 6.13 ± 0.52 on the lesions, 5.80 ± 0.41 on perilesional skin, and 5.54 ± 0.49 on uninvolved skin. In control group, the mean pH of the skin surface was 5.24 ± 0.40. The values of both parameters measured on lesional skin were significantly different (capacitance decreased and pH increased) from the values recorded on perilesional skin and uninvolved skin. The same held for the relation between perilesional and uninvolved skin. According to study results, the uninvolved skin of AD patients had significantly worse values of the measured parameters as compared with control group. The results of this study suggested the skin barrier function to be degraded in AD patients, which is specifically expressed in lesional skin.

Use of Pourbaix diagrams and the eH and pH measurements in hydrometallurgy. Part 2-Applications

International Nuclear Information System (INIS)

Teixeira, L.A.C.

1987-01-01

The interpretation of Pourbaix diagrams, presenting as examples; acid lixiviation of uranium ore, iron ion removal from process solutions, lixiviation of copper ores and cyaniding of Au ores containing Cu and Fe is presented. Practical aspects on eH and pH measurement in solutions of hydrometallurgical process. (M.C.K.) [pt

Quantified pH imaging with hyperpolarized (13) C-bicarbonate.

Science.gov (United States)

Scholz, David Johannes; Janich, Martin A; Köllisch, Ulrich; Schulte, Rolf F; Ardenkjaer-Larsen, Jan H; Frank, Annette; Haase, Axel; Schwaiger, Markus; Menzel, Marion I

2015-06-01

Because pH plays a crucial role in several diseases, it is desirable to measure pH in vivo noninvasively and in a spatially localized manner. Spatial maps of pH were quantified in vitro, with a focus on method-based errors, and applied in vivo. In vitro and in vivo (13) C mapping were performed for various flip angles for bicarbonate (BiC) and CO2 with spectral-spatial excitation and spiral readout in healthy Lewis rats in five slices. Acute subcutaneous sterile inflammation was induced with Concanavalin A in the right leg of Buffalo rats. pH and proton images were measured 2 h after induction. After optimizing the signal to noise ratio of the hyperpolarized (13) C-bicarbonate, error estimation of the spectral-spatial excited spectrum reveals that the method covers the biologically relevant pH range of 6 to 8 with low pH error (< 0.2). Quantification of pH maps shows negligible impact of the residual bicarbonate signal. pH maps reflect the induction of acute metabolic alkalosis. Inflamed, infected regions exhibit lower pH. Hyperpolarized (13) C-bicarbonate pH mapping was shown to be sensitive in the biologically relevant pH range. The mapping of pH was applied to healthy in vivo organs and interpreted within inflammation and acute metabolic alkalosis models. © 2014 Wiley Periodicals, Inc.

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

Genetically encoded proton sensors reveal activity-dependent pH changes in neurons

Directory of Open Access Journals (Sweden)

Joseph Valentino Raimondo

2012-05-01

Full Text Available The regulation of hydrogen ion concentration (pH is fundamental to cell viability, metabolism and enzymatic function. Within the nervous system, the control of pH is also involved in diverse and dynamic processes including development, synaptic transmission and the control of network excitability. As pH affects neuronal activity, and can also itself be altered by neuronal activity, the existence of tools to accurately measure hydrogen ion fluctuations is important for understanding the role pH plays under physiological and pathological conditions. Outside of their use as a marker of synaptic release, genetically encoded pH sensors have not been utilised to study hydrogen ion fluxes associated with network activity. By combining whole-cell patch clamp with simultaneous two-photon or confocal imaging, we quantified the amplitude and time course of neuronal, intracellular, acidic transients evoked by epileptiform activity in two separate in vitro models of temporal lobe epilepsy. In doing so, we demonstrate the suitability of three genetically encoded pH sensors: deGFP4, E2GFP and Cl-sensor for investigating activity-dependent pH changes at the level of single neurons.

Genetically encoded proton sensors reveal activity-dependent pH changes in neurons.

Science.gov (United States)

Raimondo, Joseph V; Irkle, Agnese; Wefelmeyer, Winnie; Newey, Sarah E; Akerman, Colin J

2012-01-01

The regulation of hydrogen ion concentration (pH) is fundamental to cell viability, metabolism, and enzymatic function. Within the nervous system, the control of pH is also involved in diverse and dynamic processes including development, synaptic transmission, and the control of network excitability. As pH affects neuronal activity, and can also itself be altered by neuronal activity, the existence of tools to accurately measure hydrogen ion fluctuations is important for understanding the role pH plays under physiological and pathological conditions. Outside of their use as a marker of synaptic release, genetically encoded pH sensors have not been utilized to study hydrogen ion fluxes associated with network activity. By combining whole-cell patch clamp with simultaneous two-photon or confocal imaging, we quantified the amplitude and time course of neuronal, intracellular, acidic transients evoked by epileptiform activity in two separate in vitro models of temporal lobe epilepsy. In doing so, we demonstrate the suitability of three genetically encoded pH sensors: deGFP4, E(2)GFP, and Cl-sensor for investigating activity-dependent pH changes at the level of single neurons.

Design of an optically stable pH sensor based on immobilization of Giemsa on triacetylcellulose membrane.

Science.gov (United States)

Khodadoust, Saeid; Kouri, Narges Cham; Talebiyanpoor, Mohammad Sharif; Deris, Jamile; Pebdani, Arezou Amiri

2015-12-01

In this work a simple, inexpensive, and sensitive optical sensor based on triacetylcellulose membrane as solid support was developed by using immobilization of Giemsa indicator for pH measurement. In this method, the influence variables on the membrane performance including pH concentration of indicator, response time, ionic strength, and reversibility were investigated. At optimum values of all variables the response of optical pH sensor is linear in the pH range of 3.0-12.0. This optical sensor was produced through simultaneous binding of the Giemsa on the activated triacetylcellulose membrane which responded to the pH changes in a broader linear range within less than 2.0 min and suitable reproducibility (RSDsensor was stable after 6 months of storage in the water/ethanol (50:50, v/v) solution without any measurable divergence in response properties (less than 5% RSD). Copyright © 2015 Elsevier B.V. All rights reserved.

Non-invasive technique to measure biogeochemical parameters (pH and O2) in a microenvironment: Design and applications

Science.gov (United States)

Li, Biting; Seliman, Ayman; Pales, Ashley; Liang, Weizhen; Sams, Allison; Darnault, Christophe; Devol, Timothy

2017-04-01

The primary objectives of this research are to do the pH and O2 sensor foils calibration and then to test them in applications. Potentially, this project can be utilized to monitor the fate and transport of radionuclides in porous media. The information for physical and chemical parameters (e.g. pH and O2) is crucial to know when determining contaminants' behavior and transport in the environment. As a non-invasive method, optical imaging technique using a DSLR camera could capture data on the foil when it fluoresces, and gives a high temporal and spatial resolution during the experimental period. The calibration procedures were done in cuvettes in a row. The preliminary experiments could measure pH value in the range from 4.5 to 7.5, and O2 concentration from 0 mg/L to 20.74 mg/L. Applications of sensor foils have involved nano zero valent and acid rain experiments in order to obtain a gradient of parameter changes.

Estimation of Hydrazine Decomposition on Measuring the High-Temperature pH in Hydrazine/ETA Solutions at 553 K

International Nuclear Information System (INIS)

Hwang, Jae Sik; Yeon, Jei Won; Yun, Myung Hee; Song, Kyu Seok; Lee, Sang Ill

2010-01-01

Hydrazine is one of the most excellent oxygen scavengers used in the secondary circuit of nuclear power plants. Furthermore, in some pants, the hydrazine is used as a source of hydrogen required to suppress radiolysis of the coolant water in the primary loop. When hydrazine was exposed in the high temperature and high pressure water, it can be decomposed into the various products such as NH 3 , N 2 , H 2 , and NO 3 ions. As the result, the pH of solution containing hydrazine in the condition of the high temperature and high pressure can be changed by those decomposed products. In the present work, we investigated the decomposition behavior of hydrazine in ETA (ethanol amine) solution. In addition, we measured the high temperature pH at 553 K on the various hydrazine/ETA solutions for confirming the applicability of the yttria stabilized zirconia (YSZ)- based pH electrode in secondary circuit of the nuclear power plants

Conformational changes in human serum albumin around the neutral pH from circular dichroic measurements

NARCIS (Netherlands)

Wilting, J.; Weideman, M.M.; Roomer, A.C.J.; Perrin, J.H.

1979-01-01

The molar ellipticity of the warfarin-albumin complex at 310 nm increases with pH from 6 to 9. This pH dependence runs parallel with that of the molar ellipticity of the albumin alone at 292 nm. The change in molar ellipticity with pH occurs in a smaller pH interval after addition of the

[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

Incidence of spontaneous bacterial peritonitis in patients with ascites. Diagnostic value of white blood cell count and pH measurement in ascitic fluid

DEFF Research Database (Denmark)

Storgaard, J S; Svendsen, Jesper Hastrup; Hegnhøj, J

1991-01-01

During a 21-month period, 65 consecutive patients admitted with ascites were included in a prospective study of the incidence of spontaneous bacterial peritonitis, and paracentesis was performed on admission. The ascitic fluid was cultured, ascitic leucocytes were counted and pH was measured....... Bacterial growth was found in five patients with chronic liver disease, who were diagnosed as having spontaneous bacterial peritonitis (SBP), since no intra-abdominal focus could be demonstrated. Thus, the incidence of SBP in this material was 7.7% (95% confidence limits: 2.5-17%). SBP was caused...

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.

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.

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.

Traceability of pH to the Mole

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Maria Filomena Camões

2015-08-01

Full Text Available Free acidity of aqueous solutions was initially defined in 1909 by Søren Peter Lauritz Sørensen as pH = −lgcH+ (c/mol·dm−3 or m/mol·kg−1 of the free hydrogen ions in solution, H+ soon (1910 was changed to pH = paH+ = −lgaH+, integrating the new concepts of activity, ai and activity coefficient γi, for the ionic species i under concern, H+ in this case; it is ai = −lg(miγi. Since individual ions do not exist alone in solution, primary pH values cannot be assigned solely by experimental measurements, requiring extra thermodynamic model assumptions for the activity coefficient, γH+, which has put pH in a unique situation of not being fully traceable to the International System of Units (SI. Also the concept of activity is often not felt to be as perceptible as that of concentration which may present difficulties, namely with the interpretation of data. pH measurements on unknown samples rely on calibration of the measuring setup with adequate reference pH buffers. In this work, the assignment of pH values to buffers closely matching the samples, e.g., seawater, is revisited. An approach is presented to assess the quantity pmH+ = −lgmH+ profiting from the fact that, contrary to single ion activity coefficients, mean activity coefficients,   can be assessed based on experimentally assessed quantities alone, γExp ±, thus ensuring traceability to the mole, the SI base unit for amount of substance. Compatibility between γExp ± and mean activity coefficient calculated by means of Pitzer model equations, γPtz ±, validates the model for its intended use.

PH measurement under pressure and at high temperatures; Mesure du pH sous pression et a temperature elevee

Energy Technology Data Exchange (ETDEWEB)

Fournie, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Le Peintre, M; Mahieu, C [Centre National de la Recherche Scientifique (CNRS), 91 - Gif-sur-Yvette (France)

1961-07-01

In the first part the development and operation of a glass electrode under pressure at room temperature is described. The pressure equilibrium between the inside and outside of the glass membrane several centimetres thick is obtained instantaneously by means of a siphon. The use of a silicone oil as electrical insulator makes possible the working of the glass electrode with the siphon at high pressures (100 kg/cm{sup 2}). In the second part, we determined the pH of various buffer solutions up to 250 deg. C using a cell of our design having two hydrogen electrodes. The values thus obtained for the buffer solutions make it possible to verify and calibrate the pH electrodes independently of the oxido-reduction potential of the medium. In the third part we give the results obtained up to 200 deg. C with the glass electrodes developed in conjunction with the Societe St Gobain. (author) [French] Dans une premiere partie, nous exposons la mise au point et le fonctionnement d'une electrode en verre sous pression a la temperature ordinaire. L'equilibrage instantane de la pression a l'interieur et a l'exterieur de la membrane en verre de quelques diziemes de millimetres d'epaisseur s'effectue par l'intermediaire d'un siphon. L'emploi d'une huile de silicone comme isolant electrique a permis le fonctionnement de l'electrode en verre a siphon sous haute pression (1000 kg/cm{sup 2}). Dans une deuxieme partie, nous avons determine jusqu'a 250 deg. C les valeurs du pH des diverses solutions tampons avec une cellule de notre conception a deux electrodes d'hydrogene. Les valeurs des solutions tampons ainsi obtenues permettent de verifier et d'etalonner les electrodes a pH independantes du potentiel d'oxydo-reduction du milieu. Dans une troisieme partie, nous relatons les resultats obtenus jusqu'a 200 deg. C avec les electrodes en verre mis au point en collaboration avec la Societe Saint-Gobain. (auteur)

Modelling lamb carcase pH and temperature decline parameters: relationship to shear force and abattoir variation.

Science.gov (United States)

Hopkins, David L; Holman, Benjamin W B; van de Ven, Remy J

2015-02-01

Carcase pH and temperature decline rates influence lamb tenderness; therefore pH decline parameters are beneficial when modelling tenderness. These include pH at temperature 18 °C (pH@Temp18), temperature when pH is 6 (Temp@pH6), and pH at 24 h post-mortem (pH24). This study aimed to establish a relationship between shear force (SF) as a proxy for tenderness and carcase pH decline parameters estimated using both linear and spline estimation models for the m. longissimus lumborum (LL). The study also compared abattoirs regarding their achievement of ideal pH decline, indicative of optimal tenderness. Based on SF measurements of LL and m. semimembranosus collected as part of the Information Nucleus slaughter programme (CRC for Sheep Industry Innovation) this study found significant relationships between tenderness and pH24LL, consistent across the meat cuts and ageing periods examined. Achievement of ideal pH decline was shown not to have significantly differed across abattoirs, although rates of pH decline varied significantly across years within abattoirs.

Evaluation of a portable urinary pH meter and reagent strips.

Science.gov (United States)

De Coninck, Vincent; Keller, Etienne Xavier; Rodríguez-Monsalve, María; Haymann, Jean-Philippe; Doizi, Steeve; Traxer, Olivier

2018-04-27

To evaluate a portable electronic pH meter and to put its accuracy in perspective with reagent strips read by a layperson, a healthcare professional and an electronic reading device. Based on a pre-analysis on 20 patients, a sample size of 77 urine aliquots from healthy volunteers was necessary to obtain sufficient study power. Measurements of urinary pH were obtained by use of reagent strips, a portable pH meter and a laboratory pH meter (gold standard). Reagents strips were read by a professional experienced in interpreting strips, a layperson, and an electronic strip reader. The mean matched pair difference between measurement methods was analyzed by the paired t-test. The degree of correlation and agreement were evaluated by the Pearson's correlation coefficient and Bland-Altman plots, respectively. The mean matched pair difference between the gold standard and all other pH measurement methods was the smallest with the portable electronic pH meter (bias 0.01, 95% CI -0.07 to 0.08; p=0.89), followed by strips read by a professional (bias -0.09, 95% CI -0.21 to 0.02; p=0.10), layperson (bias -0.17, 95% CI -0.31 to -0.04; p=0.015) and electronic strip reader (bias -0.29, 95% CI -0.41 to -0.16; pmeter achieved the highest Pearson's correlation coefficient and narrowest 95% limits of agreement, followed by strip interpretation by a professional, the electronic strip reader and the layperson. In order to quantify the ability of pH measurement methods to correctly classify values within a predefined urinary pH target range, we performed classification tests for several stones. The portable electronic pH meter outperformed all other measurement methods for negative predictive values. Findings of the current study support that the portable electronic pH meter is a reliable pH measuring device. It seems to be more accurate compared to reagent strips readings.

The measurement of the temperature, pH and the electric properties of the liquid of the borehole

International Nuclear Information System (INIS)

Duran, O.; Magnusson, K.Aa.

1980-05-01

Some new measurement methods to log variations of properties in a borehole have been described. The measurements have been made 'in situ' at resp Kraakemaala, Finnsjoen and Studsvik, all in Sweden. The investigation is assumed to give evidence of the fissures in the bedrock. The work is part of a programme concerning waste management. The following properties in boreholes are presented in a number of graphs: temperature, liquid resistivity, pH, self potentials and redox potentials. The experimental results are reproducible and systematic. (G.B.)

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.

A quantum dot-spore nanocomposite pH sensor.

Science.gov (United States)

Zhang, Xingya; Li, Zheng; Zhou, Tao; Zhou, Qian; Zeng, Zhiming; Xu, Xiangdong; Hu, Yonggang

2016-04-01

A new quantum dot (QD)-based pH sensor design is investigated. The sensor is synthesized based on the self-assembly of green QDs onto treated spores to form QD@spore nanocomposites. The nanocomposites are characterized using laser scanning confocal microscopy, transmission electron microscope, and fluorescence spectroscopy, among others. Fluorescence measurements showed that these nanocomposites are sensitive to pH in a broad pH range of 5.0-10.0. The developed pH sensors have been satisfactorily applied for pH estimation of real samples and are comparable with those of the commercial assay method, indicating the potential practical application of the pH sensors. Copyright © 2015 Elsevier B.V. All rights reserved.

Empirical Algorithms to Predict pH and Aragonite Saturation State on SOCCOM Biogeochemical Argo Floats in the Pacific Sector of the Southern Ocean

Science.gov (United States)

Williams, N. L.; Juranek, L. W.; Feely, R. A.; Johnson, K. S.; Russell, J. L.

2016-02-01

The Southern Ocean plays a major role in the global uptake, transport, and storage of both heat and carbon, yet it remains one of the least-sampled regions of the ocean. The Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) project aims to fill the observational gaps by deploying over 200 autonomous profiling floats in the Southern Ocean over the next several years. Initial float deployments have greatly expanded our observational capability to include wintertime measurements as well as under-ice measurements, and many of these floats include novel biogeochemical sensors (pH, nitrate, oxygen). Here we present empirical algorithms that can be used to predict pH and ΩAragonite from other float-measured parameters (temperature, salinity, pressure, nitrate, oxygen). These algorithms were trained using bottle measurements from high-quality repeat hydrographic GO-SHIP cruises. We obtained R2 values of 0.98 (pH) and 0.99 (ΩAragonite) and RMS errors of 0.007 (pH) and 0.052 (ΩAragonite) for data between 100-1500 m. These algorithms will allow us to both validate pH data from these sensors, as well as predict ΩAragonite and pH on floats that do not have pH sensors. Here we present estimated pH and ΩAragonite over 20 months of deployment for several SOCCOM floats in the Pacific Sector of the Southern Ocean. The results show seasonal ranges in surface pH and ΩAragonite of 0.05 and 0.1, respectively.

An analysis of dietary fiber and fecal fiber components including pH in rural Africans with colorectal cancer

Directory of Open Access Journals (Sweden)

Mohammed Faruk

2018-01-01

Full Text Available Background/Aims: Colorectal cancer (CRC is now a major public health problem with heavy morbidity and mortality in rural Africans despite the lingering dietary fiber-rich foodstuffs consumption. Studies have shown that increased intake of dietary fiber which contribute to low fecal pH and also influences the activity of intestinal microbiota, is associated with a lowered risk for CRC. However, whether or not the apparent high dietary fiber consumption by Africans do not longer protects against CRC risk is unknown. This study evaluated dietary fiber intake, fecal fiber components and pH levels in CRC patients. Methods: Thirty-five subjects (CRC=21, control=14, mean age 45 years were recruited for the study. A truncated food frequency questionnaire and modified Goering and Van Soest procedures were used. Results: We found that all subjects consumed variety of dietary fiber-rich foodstuffs. There is slight preponderance in consumption of dietary fiber by the control group than the CRC patients. We also found a significant difference in the mean fecal neutral detergent fiber, acid detergent fiber, hemicellulose, cellulose and lignin contents from the CRC patients compared to the controls (P<0.05. The CRC patients had significantly more fecal pH level than the matched apparently healthy controls (P=0.017. Conclusions: The identified differences in the fecal fiber components and stool pH levels between the 2 groups may relate to CRC incidence and mortality in rural Africans. There is crucial need for more hypothesis-driven research with adequate funding on the cumulative preventive role of dietary fiber-rich foodstuffs against colorectal cancer in rural Africans “today.”

Standard test method for measuring pH of soil for use in corrosion testing

CERN Document Server

American Society for Testing and Materials. Philadelphia

1995-01-01

1.1 This test method covers a procedure for determining the pH of a soil in corrosion testing. The principle use of the test is to supplement soil resistivity measurements and thereby identify conditions under which the corrosion of metals in soil may be accentuated (see G 57 - 78 (1984)). 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Effect of single oral dose of tramadol on gastric secretions pH

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Khan Mueen Ullah

2015-01-01

Full Text Available Background: Tramadol is an atypical analgesic agent. It has been shown that intramuscular or intravenous injection tramadol is able to inhibit M3 muscarinic receptors. Tramadol is able to mediate smooth muscles contraction and glandular secretions. We have evaluated the effects of single oral dose of tramadol given preoperatively on gastric juices pH in patients electively scheduled for laparoscopic cholecystectomy. Materials and Methods: Sixty adult, American Society of Anesthesiologist I and II patients scheduled for laparoscopic cholecystectomy were included in the study. Patients were randomly assigned to receive either placebo (n = 30 or oral tramadol 50 mg (n = 30. General anesthesia was induced using propofol, fentanyl and cisatracurium. After induction of anesthesia 5 ml of gastric fluid was aspirated through orogastric tube. The gastric fluid pH was measured using pH meter. Result: There was no significant difference in the pH between the groups. Gastric pH of the placebo and tramadol groups was 1.97 versus 1.98 (P = 0.092 respectively. Conclusion: Preoperatively single oral dose of tramadol was unable to elevate the desired level of gastric acid secretions pH (>2.5. This may be due to pharmacokinetic disparity between the analgesic and pH elevating properties of tramadol.

Monitoring Intracellular pH Change with a Genetically Encoded and Ratiometric Luminescence Sensor in Yeast and Mammalian Cells.

Science.gov (United States)

Zhang, Yunfei; Robertson, J Brian; Xie, Qiguang; Johnson, Carl Hirschie

2016-01-01

"pHlash" is a novel bioluminescence-based pH sensor for measuring intracellular pH, which is developed based on Bioluminescence Resonance Energy Transfer (BRET). pHlash is a fusion protein between a mutant of Renilla luciferase (RLuc) and a Venus fluorophore. The spectral emission of purified pHlash protein exhibits pH dependence in vitro. When expressed in either yeast or mammalian cells, pHlash reports basal pH and cytosolic acidification. In this chapter, we describe an in vitro characterization of pHlash, and also in vivo assays including in yeast cells and in HeLa cells using pHlash as a cytoplasmic pH indicator.

A microbent fiber optic pH sensor

NARCIS (Netherlands)

Thomas Lee, S.; Aneeshkumar, B.N.; Radhakrishnan, P.; Vallabhan, C.P.G.; Nampoori, V.P.N.

2002-01-01

Optical fiber sensors developed for measuring pH values usually employ an unclad and unstrained section of the fiber. In this paper, we describe the design and fabrication of a microbent fiber optic sensor that can be used for pH sensing. In order to obtain the desired performance, a permanently

De Svante Arrhenius ao peagâmetro digital: 100 anos de medida de acidez From Svante Arrhenius to the digital ph meter: a century of acidity measurement

Directory of Open Access Journals (Sweden)

Michelle da Silva Gama

2007-02-01

Full Text Available This work describes the establishment of the concept of pH and the evolution of its measurement. The origin of the pH definition can be found in the development of the chemistry of aqueous solutions during the XIXth century. The electrolytic dissociation theory by Svante Arrhenius played a central role. After the proposal of the pH scale by Sörensen, many years were necessary for the acceptance of this new parameter among chemists in general. Its importance was first recognized in biochemistry and related areas. Twenty years after, its importance had been recognized in many industrial and laboratorial practices. The previous methods were based on colorimetric and electrometric methods, but both suffered from many problems. Acceptance of pH in Chemistry was only possible after the development of experimental trustable measurements. The invention of the pH meter was the primordial step.

CARINA data synthesis project: pH data scale unification and cruise adjustments

Directory of Open Access Journals (Sweden)

A. Velo

2010-05-01

Full Text Available Data on carbon and carbon-relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruise data sets in the Artic Mediterranean Seas (AMS, Atlantic Ocean and Southern Ocean have been retrieved and merged to a new database: CARINA (CARbon IN the Atlantic Ocean.

These data have gone through rigorous quality control (QC procedures to assure the highest possible quality and consistency. The data for most of the measured parameters in the CARINA database were objectively examined in order to quantify systematic differences in the reported values. Systematic biases found in the data have been corrected in the data products, three merged data files with measured, calculated and interpolated data for each of the three CARINA regions; AMS, Atlantic Ocean and Southern Ocean. Out of a total of 188 cruise entries in the CARINA database, 59 reported pH measured values. All reported pH data have been unified to the Sea-Water Scale (SWS at 25 °C.

Here we present details of the secondary QC of pH in the CARINA database and the scale unification to SWS at 25 °C. The pH scale has been converted for 36 cruises. Procedures of quality control, including crossover analysis between cruises and inversion analysis are described. Adjustments were applied to the pH values for 21 of the cruises in the CARINA dataset. With these adjustments the CARINA database is consistent both internally as well as with the GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s. Based on our analysis we estimate the internal consistency of the CARINA pH data to be 0.005 pH units. The CARINA data are now suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates, for ocean acidification assessment and for model validation.

Reliability of Measured Data for pH Sensor Arrays with Fault Diagnosis and Data Fusion Based on LabVIEW

OpenAIRE

Liao, Yi-Hung; Chou, Jung-Chuan; Lin, Chin-Yi

2013-01-01

Fault diagnosis (FD) and data fusion (DF) technologies implemented in the LabVIEW program were used for a ruthenium dioxide pH sensor array. The purpose of the fault diagnosis and data fusion technologies is to increase the reliability of measured data. Data fusion is a very useful statistical method used for sensor arrays in many fields. Fault diagnosis is used to avoid sensor faults and to measure errors in the electrochemical measurement system, therefore, in this study, we use fault diagn...

Electrocatalytic hydrogen evolution under densely buffered neutral pH conditions

KAUST Repository

Shinagawa, Tatsuya

2015-08-18

Under buffered neutral pH conditions, solute concentrations drastically influence the hydrogen evolution reaction (HER). The iR-free HER performance as a function of solute concentration was found to exhibit a volcano-shaped trend in sodium phosphate solution at pH 5, with the maximum occurring at 2 M. A detailed microkinetic model that includes calculated activity coefficients, solution resistance, and mass-transport parameters accurately describes the measured values, clarifying that the overall HER performance is predominantly governed by mass-transport of slow phosphate ions (weak acid). In the HER at the optimum concentration of approximately 2 M sodium phosphate at pH 5, our theoretical model predicts that the concentration overpotential accounts for more than half of the required overpotential. The substantial concentration overpotential would originate from the electrolyte property, suggesting that the proper electrolyte engineering will result in an improved apparent HER performances. The significance of concentration overpotential shown in the study is critical in the advancement of electrocatalysis, biocatalysis, and photocatalysis.

Electrocatalytic hydrogen evolution under densely buffered neutral pH conditions

KAUST Repository

Shinagawa, Tatsuya; Takanabe, Kazuhiro

2015-01-01

Under buffered neutral pH conditions, solute concentrations drastically influence the hydrogen evolution reaction (HER). The iR-free HER performance as a function of solute concentration was found to exhibit a volcano-shaped trend in sodium phosphate solution at pH 5, with the maximum occurring at 2 M. A detailed microkinetic model that includes calculated activity coefficients, solution resistance, and mass-transport parameters accurately describes the measured values, clarifying that the overall HER performance is predominantly governed by mass-transport of slow phosphate ions (weak acid). In the HER at the optimum concentration of approximately 2 M sodium phosphate at pH 5, our theoretical model predicts that the concentration overpotential accounts for more than half of the required overpotential. The substantial concentration overpotential would originate from the electrolyte property, suggesting that the proper electrolyte engineering will result in an improved apparent HER performances. The significance of concentration overpotential shown in the study is critical in the advancement of electrocatalysis, biocatalysis, and photocatalysis.

Effect of pH on structure, function, and stability of mitochondrial carbonic anhydrase VA.

Science.gov (United States)

Idrees, Danish; Shahbaaz, Mohd; Bisetty, Krishna; Islam, Asimul; Ahmad, Faizan; Hassan, Md Imtaiyaz

2017-02-01

Mitochondrial carbonic anhydrase VA (CAVA) catalyzes the hydration of carbon dioxide to produce proton and bicarbonate which is primarily expressed in the mitochondrial matrix of liver, and involved in numerous physiological processes including lipogenesis, insulin secretion from pancreatic cells, ureagenesis, gluconeogenesis, and neuronal transmission. To understand the effect of pH on the structure, function, and stability of CAVA, we employed spectroscopic techniques such as circular dichroism, fluorescence, and absorbance measurements in wide range of pH (from pH 2.0 to pH 11.5). CAVA showed an aggregation at acidic pH range from pH 2.0 to pH 5.0. However, it remains stable and maintains its secondary structure in the pH range, pH 7.0-pH 11.5. Furthermore, this enzyme has an appreciable activity at more than pH 7.0 (7.0 < pH ≤ 11.5) with maximum activity at pH 9.0. The maximal values of k cat and k cat /K m at pH 9.0 are 3.7 × 10 6  s -1 and 5.5 × 10 7  M -1  s -1 , respectively. However, this enzyme loses its activity in the acidic pH range. We further performed 20-ns molecular dynamics simulation of CAVA to see the dynamics at different pH values. An excellent agreement was observed between in silico and in vitro studies. This study provides an insight into the activity of CAVA in the pH range of subcellular environment.

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.

A Reliable and Non-destructive Method for Monitoring the Stromal pH in Isolated Chloroplasts Using a Fluorescent pH Probe

Directory of Open Access Journals (Sweden)

Pai-Hsiang Su

2017-12-01

Full Text Available The proton gradient established by the pH difference across a biological membrane is essential for many physiological processes, including ATP synthesis and ion and metabolite transport. Currently, ionophores are used to study proton gradients, and determine their importance to biological functions of interest. Because of the lack of an easy method for monitoring the proton gradient across the inner envelope membrane of chloroplasts (ΔpHenv, whether the concentration of ionophores used can effectively abolish the ΔpHenv is not proven for most experiments. To overcome this hindrance, we tried to setup an easy method for real-time monitoring of the stromal pH in buffered, isolated chloroplasts by using fluorescent pH probes; using this method the ΔpHenv can be calculated by subtracting the buffer pH from the measured stromal pH. When three fluorescent dyes, BCECF-AM [2′,7′-bis-(2-carboxyethyl-5-(and-6-carboxyfluorescein acetoxymethyl ester], CFDA-SE [5(6-Carboxyfluorescein diacetate succinimidyl ester] and SNARF-1 carboxylic acid acetate succinimidyl ester were incubated with isolated chloroplasts, BCECF-AM and CFDA-SE, but not the ester-formed SNARF-1 were taken up by chloroplasts and digested with esterase to release high levels of fluorescence. According to its relatively higher pKa value (6.98, near the physiological pH of the stroma, BCECF was chosen for further development. Due to shielding of the excitation and emission lights by chloroplast pigments, the ratiometric fluorescence of BCECF was highly dependent on the concentration of chloroplasts. By using a fixed concentration of chloroplasts, a highly correlated standard curve of pH to the BCECF ratiometric fluorescence with an r-square value of 0.98 was obtained, indicating the reliability of this method. Consistent with previous reports, the light-dependent formation of ΔpHenv can be detected ranging from 0.15 to 0.33 pH units upon illumination. The concentration of the ionophore

Impact of pH on Urine Chemistry Assayed on Roche Analyzers.

Science.gov (United States)

Cohen, R; Alkouri, R; Tostivint, I; Djiavoudine, S; Mestari, F; Dever, S; Atlan, G; Devilliers, C; Imbert-Bismut, F; Bonnefont-Rousselot, D; Monneret, D

2017-10-01

The pH may impact the concentration of certain urinary parameters, making urine pre-treatment questionable. 1) Determining the impact of pH in vitro on the urinary concentration of chemistry parameters assayed on Roche Modular analyzers. 2) Evaluating whether concentrations depended on pH in non-pretreated urines from patients. 1) The optimal urinary pH values for each measurement were: 6.3 ± 0.8 (amylase), 6.5 (uric acid). Urinary creatinine, sodium and urea concentrations were not pH-dependent. 2) In urines from patients, the pH was negatively associated with the concentration of some urinary parameters. However, concentrations of all the parameters were strongly and positively correlated with urinary creatinine, and relationships with pH were no longer evidenced after creatinine-normalization. The need for urine pH adjustment does not seem necessary when considering renal function. However, from an analytical and accreditation standpoint, the relationship between urine pH and several parameters justifies its measurement.

Experimental measurements of the solubilities of selected long-lived fission products, activation products and actinide daughters under high pH conditions

International Nuclear Information System (INIS)

Pilkington, N.J.; Shadbolt, P.J.; Wilkins, J.D.

1988-05-01

Solubility measurements of several elements have been attempted under high pH and oxic conditions in a range of concrete leachates. The elements investigated were niobium, tin, selenium, lead and thorium. (author)

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...

In-situ pH measurements and sample analyses in glass-iron-clay systems at 90 deg. C and 150 deg. C

International Nuclear Information System (INIS)

Rozsypal, Christophe; Mosser-Ruck, Regine; Truche, Laurent; Pignatelli, Isabella; Randi, Aurelien; Bartier, Daniele; Cathelineau, Michel; Michau, Nicolas

2012-01-01

Document available in extended abstract form only. The long term repository of long life and high activity radioactive waste consists in the burial of steel overpacks of vitrified waste in a clay-stone. As the natural interstitial fluid of the clay-stone is a potential corrosion enhancer for the containers, the viability of the repository requires previous data acquisition on the interactions between clays, water, metallic iron, and glass. A set of experiments have been performed in autoclaves at 90 deg. C (thermal peak of the site) in order to follow the pH evolution and to characterize fluids with time and solids at the end of the experiments. Another set of experiments at 150 deg. C have also been carried out in order to increase the rates of the involved chemical reactions and mineralogical transformations. The objectives of those two sets of experiments were to measure the in-situ pH, to study how it was influenced by various parameters, such as the presence of glass and/or iron, to estimate the increase of the CO 2 and H 2 pressures, and to analyze gas and liquids taken in the course or at the end of experiments and solids recovered at the end of the experiments. The initial aqueous solution simulating the natural interstitial fluid was made of 22 mM of sodium, 4 mM of calcium, 29.75 mM of chloride, and 0.25 mM of bromide as a tracer. The initial solution/clay mass ratio was 10 for all the experiments, the metallic iron/clay or glass/clay mass ratios were 0.1 or 0. The list of the experiments and their characteristics is given in Table (1). The first results concern the evolution of the in-situ pH during the A90pH experiment and are reported on Figure (1). The measurements started after a 48 hours stabilization time of the pH probe. The pH seemed to tend reaching a plateau after several weeks. (authors)

pH Sensing and Regulation in Cancer

Directory of Open Access Journals (Sweden)

Mehdi eDamaghi

2013-12-01

Full Text Available 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. In this review, we will discuss some of the major players in proton sensing at the plasma membrane and their downstream consequences in cancer cells and how these pH-mediated changes affect processes such as migration and metastasis. The complex mechanisms by which they transduce acid pH signals to the cytoplasm and nucleus are not well understood. However, there is evidence that expression of proton-sensing GPCRs such as GPR4, TDAG8, and OGR1 can regulate aspects of tumorigenesis and invasion, including colfilin and talin regulated actin (de-polymerization. Major mechanisms for maintenance of pHi homeostasis include monocarboxylate, bicarbonate and proton transporters. Notably, there is little evidence suggesting a link between their activities and those of the extracellular H+-sensors, suggesting a mechanistic disconnect between intra- and extra-cellular pH. Understanding the mechanisms of pH sensing and regulation may lead to novel and informed therapeutic strategies that can target acidosis, a common physical hallmark of solid tumors.

Continuous measurement of reticuloruminal pH values in dairy cows during the transition period from barn to pasture feeding using an indwelling wireless data transmitting unit.

Science.gov (United States)

Gasteiner, J; Horn, M; Steinwidder, A

2015-04-01

This study was performed to investigate the effect of the transition from barn feeding to pasture on the pattern of reticuloruminal pH values in 8 multiparous dairy cows. A indwelling wireless data transmitting system for pH measurement was given to 8 multiparous cows orally. Reticuloruminal pH values were measured every 600 s over a period of 42 days. After 7 days of barn feeding (period 1), all of the animals were pastured with increasing grazing times from 2 to 7 h/day over 7 days (period 2). From day 15 to day 21 (period 3), the cows spent 7 h/day on pasture. Beginning on day 22, the animals had 20 h/day access to pasture (day and night grazing). To study reticuloruminal adaptation to pasture feeding, the phase of day and night grazing was subdivided into another 3 weekly periods (periods 4-6). Despite a mild transition period from barn feeding to pasture, significant effects on reticuloruminal pH values were observed. During barn feeding, the mean reticuloruminal pH value for all of the cows was 6.44 ± 0.14, and the pH values decreased significantly (p pH values increased again (pH 6.25 ± 0.22; pH 6.31 ± 0.17; pH 6.37 ± 0.16). Our results showed that the animals had significantly lowered reticuloruminal pH during the periods of feed transition from barn to pasture feeding. Despite these significant changes, the decrease was not harmful, as indicated by data of feed intake and milk production. Journal of Animal Physiology and Animal Nutrition © 2014 Blackwell Verlag GmbH.

Relieving Dry Mouth: Varying Levels of pH Found in Bottled Water.

Science.gov (United States)

Fisher, Bailey Jean; Spencer, Angela; Haywood, Van; Konchady, Gayathri

2017-07-01

It is estimated that 30% of people older than 60 years suffer from hyposalivation or dry mouth. Drinking water frequently has been recommended as a safe, non-pharmacologic way to combat hyposalivation. The saliva in patients with dry mouth is acidic. Beverages consumed daily may have an erosive potential on teeth. The pH and the mineral content of the beverage determine its erosive potential. An acidic beverage, therefore, may have harmful effects on mineralized tooth structures, causing erosion of enamel, dentin, and cementum. Because bottled water is both convenient and easily available, the authors tested the pH of eight common brands of bottled water. (One brand included two different bottle types, for a total of nine bottled waters tested.) To standardize the pH electrode, pH buffers of 4.7 and 10 were used. The pH was measured using the Denver Instruments basic pH meter. Six recordings were used for each brand and then averaged to report the pH. Two of the bottled water samples tested were below the critical level of 5.2 pH to 5.5 pH, the level at which erosion of enamel occurs. Six of the samples tested were below the critical pH of 6.8, at which erosion of root dentin occurs. The authors conclude that both patients and clinicians incorrectly presume bottled water to be innocuous. Clinicians should be cognizant of the erosive potential of different brands of bottled water to both educate patients and to recommend water with neutral or alkaline pH for patients with symptoms of dry mouth to prevent further deterioration and demineralization of tooth structure.

Usefulness of saliva for measurement of 3,4-methylenedioxymethamphetamine and its metabolites: correlation with plasma drug concentrations and effect of salivary pH.

Science.gov (United States)

Navarro, M; Pichini, S; Farré, M; Ortuño, J; Roset, P N; Segura, J; de la Torre, R

2001-10-01

Saliva is an alternative biologic matrix for drugs-of-abuse testing that offers the advantages of noninvasive, rapid, and easy sampling. We studied the excretion profile of 3,4-methylenedioxymethamphetamine (MDMA) and its metabolites in both saliva and plasma, as well the effect of the drug on salivary pH. Saliva and plasma samples were obtained from eight healthy MDMA consumers after ingestion of a single 100-mg dose of the drug. Concentrations of MDMA and its main metabolites, 3,4-methylenedioxyamphetamine (MDA) and 4-hydroxy-3-methoxymethamphetamine (HMMA), in saliva and plasma were measured by gas chromatography-mass spectrometry. Apparent pharmacokinetic parameters for MDMA in saliva were estimated, and the saliva-to-plasma ratio at each time interval was calculated and correlated with salivary pH. MDMA, MDA, and HMMA were detected in saliva. Salivary concentrations of MDMA were 1728.9-6510.6 microg/L and peaked at 1.5 h after drug intake. This was followed by a progressive decrease, with a mean concentration of 126.2 microg/L at 24 h. The saliva-to-plasma ratio was 32.3-1.2, with a peak of 18.1 at 1.5 h after drug administration. Salivary pH seemed to be affected by MDMA administration; pH values decreased by 0.6 units (mean pH values of 6.9 and 6.8 at 1.5 and 4 h after drug administration vs predose pH of 7.4). Measurement of MDMA in saliva is a valuable alternative to determination of plasma drug concentrations in both clinical and toxicologic studies. On-site testing is also facilitated by noninvasive and rapid collection of salivary specimens.

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.

High Ph, Ammonia Toxicity, and the Search for Life on the Jovian Planets

Science.gov (United States)

Deal, P. H.; Souza, K. A.; Mack, H. M.

1975-01-01

The effects of pH and ammonia concentration were studied separately, where possible, on a variety of organisms, including some isolated from natural environments of high pH and/or ammonia concentration. Escherichia coli and Bacillus subtilis are both extremely sensitive to ammonia. An aerobic organism (growth up to pH 11.4) from an alkaline spring is more resistant, but exhibits a toxic response to ammonia at a pH much lower than its maximum for growth. The greatest ammonia resistance has been found in an unidentified organism growing at near neutral pH. Even in this case, however, urvival at ammonia concentrations reasonably expected on the Jovian planets is measured in hours. This is two to three orders of magnitude longer than for E. coli. Results support the tentative conclusion that contamination of the Jovian planets with terrestrial organisms that can grow is unlikely. However, the range of toxic response noted, coupled with the observation that terrestrial life has not been exposed to high ammonia concentrations for millions of years, suggests that adaptation to greater ammonia tolerance may be possible.

Qualitative methods in PhD theses from general practice in Scandinavia

DEFF Research Database (Denmark)

Malterud, Kirsti; Hamberg, Katarina; Reventlow, Susanne

2017-01-01

. Qualitative studies are often included in Ph.D. theses from general practice in Scandinavia. Still, the Ph.D. programs across nations and institutions offer only limited training in qualitative methods. In this opinion article, we draw upon our observations and experiences, unpacking and reflecting upon...... values and challenges at stake when qualitative studies are included in Ph.D. theses. Hypotheses to explain these observations are presented, followed by suggestions for standards of evaluation and improvement of Ph.D. programs. The authors conclude that multimethod Ph.D. theses should be encouraged...

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.

Explaining the variation in the shear force of lamb meat using sarcomere length, the rate of rigor onset and pH.

Science.gov (United States)

Hopkins, D L; Toohey, E S; Lamb, T A; Kerr, M J; van de Ven, R; Refshauge, G

2011-08-01

The temperature when the pH=6.0 (temp@pH6) impacts on the tenderness and eating quality of sheep meat. Due to the expense, sarcomere length is not routinely measured as a variable to explain variation in shear force, but whether measures such as temp@pH6 are as useful a parameter needs to be established. Measures of rigor onset in 261 carcases, including the temp@pH6, were evaluated in this study for their ability to explain some of the variation in shear force. The results show that for 1 day aged product combinations of the temp@pH6, the pH at 18 °C and the pH at 24 h provided a larger reduction (almost double) in total shear force variation than sarcomere length alone, with pH at 24 h being the single best measure. For 5 day aged product, pH at 18 °C was the single best measure. Inclusion of sarcomere length did represent some improvement, but the marginal increase would not be cost effective. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

SALIVARY PH CHANGES AFTER GIC RESTORATION ON DECIDUOUS TEETH

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Chandra Nila Sukma

2015-06-01

Full Text Available Glass Ionomer Cement (GIC is the most widely used material in pediatric dentistry. The purpose of this study was to analyze pH changes of saliva after GIC restoration on primary teeth. For this purpose, 20 primary canines which were restored with GIC 24 hours previously were plunged into 20 tubes containing each 1,5 ml pH 6,8 Fusayama artificial saliva and then stored in incubator at the temperature of 37°C. The pH changes were measured at 30, 60, and 90 minutes later with digital pH meter PH-201. It was revealed that the highest pH acceleration was at 30 minutes exposure an decrease thereafter and the lowest pH acceleration was at 90 minutes exposure. Statistical analysis was performed by Anova and Tukey HSD.

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.

An analysis of dietary fiber and fecal fiber components including pH in rural Africans with colorectal cancer.

Science.gov (United States)

Faruk, Mohammed; Ibrahim, Sani; Adamu, Ahmed; Rafindadi, Abdulmumini Hassan; Ukwenya, Yahaya; Iliyasu, Yawale; Adamu, Abdullahi; Aminu, Surajo Mohammed; Shehu, Mohammed Sani; Ameh, Danladi Amodu; Mohammed, Abdullahi; Ahmed, Saad Aliyu; Idoko, John; Ntekim, Atara; Suleiman, Aishatu Maude; Shah, Khalid Zahir; Adoke, Kasimu Umar

2018-01-01

Colorectal cancer (CRC) is now a major public health problem with heavy morbidity and mortality in rural Africans despite the lingering dietary fiber-rich foodstuffs consumption. Studies have shown that increased intake of dietary fiber which contribute to low fecal pH and also influences the activity of intestinal microbiota, is associated with a lowered risk for CRC. However, whether or not the apparent high dietary fiber consumption by Africans do not longer protects against CRC risk is unknown. This study evaluated dietary fiber intake, fecal fiber components and pH levels in CRC patients. Thirty-five subjects (CRC=21, control=14), mean age 45 years were recruited for the study. A truncated food frequency questionnaire and modified Goering and Van Soest procedures were used. We found that all subjects consumed variety of dietary fiber-rich foodstuffs. There is slight preponderance in consumption of dietary fiber by the control group than the CRC patients. We also found a significant difference in the mean fecal neutral detergent fiber, acid detergent fiber, hemicellulose, cellulose and lignin contents from the CRC patients compared to the controls ( P fiber components and stool pH levels between the 2 groups may relate to CRC incidence and mortality in rural Africans. There is crucial need for more hypothesis-driven research with adequate funding on the cumulative preventive role of dietary fiber-rich foodstuffs against colorectal cancer in rural Africans "today."

Paulette Gray, Ph.D.

Science.gov (United States)

Paulette S. Gray, Ph.D. is the Director for the Division of Extramural Activities (DEA). As the director of the division, she is responsible for the overall scientific, fiscal, and administrative management of the division, including broad strategic planning, development, implementation, and evaluation.

Drilling and the associated drillhole measurements of the pilot hole ONK-PH6

International Nuclear Information System (INIS)

Oehberg, A.; Hirvonen, H.; Kemppainen, K.; Niemonen, J.; Nordbaeck, N.; Poellaenen, J.; Rouhiainen, P.; Rautio, T.; Tarvainen, A.-M.

2007-08-01

The construction of the ONKALO access tunnel started in September 2004 at Olkiluoto. Most of the investigations related to the construction of the access tunnel aim to ensure successful excavations, reinforcement and sealing. Pilot holes are drillholes, which are core drilled along the tunnel profile. The length of the pilot holes typically varies from several tens of metres to a couple of hundred metres. The pilot holes are aimed to confirm the quality of the rock mass for tunnel construction, and in particular to identify water conductive fractured zones and to provide information that could result in modifications of the existing construction plans. The pilot hole ONK-PH6 was drilled from chainage 1404 to chainage 1559 in September 2006. The length of the hole is 155.04 m. The aim during the drilling work was to orient core samples as much as possible. The deviation of the drillhole was measured during and after the drilling phase. One steering operation by wedging was made at the hole depth of 94.05 metres (top of the wedge). Electric conductivity was measured from the collected returning water samples. Logging of the core samples included the following parameters: lithology, foliation, fracturing, fracture frequency, RQD, fractured zones, core loss and weathering. The rock mechanical logging was based on Q-classification. The tests to determine rock strength and deformation properties were made with a Rock Tester-equipment. Difference Flow method was used for the determination of hydraulic conductivity in fractures and fractured zones in the drillhole. The overlapping i.e. the detailed flow logging mode was used. Besides flow logging Single Point Resistance (SPR), Electric Conductivity (EC) and temperature of the drillhole water were also measured. The flow logging was performed with 0.5 m section length and with 0.1 m depth increment. Water loss tests were conducted in the hole excluding the section 89.04 - 101.04 metres due to the wedge. Geophysical logging

The effect of a hay grid feeder on feed consumption and measurement of the gastric pH using an intragastric electrode device in horses: a preliminary report.

Science.gov (United States)

Aristizabal, F; Nieto, J; Yamout, S; Snyder, J

2014-07-01

Obesity and gastric ulceration are highly prevalent in horses. Management modifications for preventing squamous gastric ulceration include frequent feeding and free access to pasture; however, these practices may predispose horses to obesity. To compare the percentage of hay consumed, intragastric pH and horse activity between feeding from the ground and a hay grid feeder. Crossover experimental study. A pH electrode was inserted into the stomach to record the intragastric pH for 48 h. Horses received 1% of their body weight in grass hay twice a day. Horses were assigned to be fed from the ground or a commercial hay grid feeder for 24 h and then switched to the opposite protocol for an additional 24 h. Horses were continuously video-recorded and the percentage of time spent eating or drinking, walking or standing, and lying down were calculated. Two point data were compared by paired t test and pH over time was compared by repeated measures ANOVA. Horses consumed significantly greater amounts of grass hay when fed on the ground compared with a hay grid feeder (n = 9; PpH values (n = 6; P = 0.97), mean intragastric pH over time (n = 6; P = 0.45) the length of time the pH was below 4.0 (n = 6; P = 0.54), and the percentage of time horses spent eating or drinking (n = 9; P = 0.52), walking or standing (n = 9; P = 0.3), or lying down (n = 9; P = 0.4). Within each group horses spent more time eating during the day compared with the night (n = 9; hay grid feeder P = 0.003; ground feeding P = 0.007). The hay grid feeder studied may be used to reduce the amount of hay ingested by horses without reducing the time horses spend eating. © 2013 EVJ Ltd.

Soil pH Mapping with an On-The-Go Sensor

OpenAIRE

Schirrmann, Michael; Gebbers, Robin; Kramer, Eckart; Seidel, Jan

2011-01-01

Soil pH is a key parameter for crop productivity, therefore, its spatial variation should be adequately addressed to improve precision management decisions. Recently, the Veris pH ManagerTM, a sensor for high-resolution mapping of soil pH at the field scale, has been made commercially available in the US. While driving over the field, soil pH is measured on-the-go directly within the soil by ion selective antimony electrodes. The aim of this study was to evaluate the Veris pH ManagerTM under ...

Intracellular pH in rat pancreatic ducts

DEFF Research Database (Denmark)

Novak, I; Hug, M; Greger, R

1997-01-01

In order to study the mechanism of H+ and HCO3- transport in a HCO3- secreting epithelium, pancreatic ducts, we have measured the intracellular pH (pHi) in this tissue using the pH sensitive probe BCECF. We found that exposures of ducts to solutions containing acetate/acetic acid or NH4+/NH3...... buffers (20 mmol/l) led to pHi changes in accordance with entry of lipid-soluble forms of the buffers, followed by back-regulation of pHi by duct cells. In another type of experiment, changes in extracellular pH of solutions containing HEPES or HCO3-/CO2 buffers led to significant changes in pHi that did....... Under some conditions, these exchangers can be invoked to regulate cell pH....

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.

Reference value standards and primary standards for pH measurements in D2O and aqueous-organic solvent mixtures: new accessions and assessments

International Nuclear Information System (INIS)

Mussini, P.R.; Mussini, T.; Rondinini, S.

1997-01-01

Recommended Reference Value Standards based on the potassium hydro-genphthalate buffer at various temperatures are reported for pH measurements in various binary solvent mixtures of water with eight organic solvents: methanol, ethanol, 2-propanol, 1,2-ethanediol, 2-methoxyethanol (''methylcellosolve''), acetonitrile, 1,4-dioxane, and dimethyl sulfoxide, together with Reference Value Standard based on the potassium deuterium phthalate buffer for pD measurements in D 2 O. In addition are reported Primary Standards for pH based on numerous buffers in various binary solvent mixtures of water with methanol, ethanol, and dimethyl sulfoxide, together with Primary Standards for pD in D 2 O based on the citrate, phosphate and carbonate buffers. (author)

Birth asphyxia measured by the pH value of the umbilical cord blood may predict an increased risk of attention deficit hyperactivity disorder.

Science.gov (United States)

Mikkelsen, Susanne Hvolgaard; Olsen, Jørn; Bech, Bodil Hammer; Wu, Chunsen; Liew, Zeyan; Gissler, Mika; Obel, Carsten; Arah, Onyebuchi

2017-06-01

Although birth asphyxia is a major risk factor for neonatal and childhood morbidity and mortality, it has not been investigated much in relation to attention deficit hyperactivity disorder (ADHD). We examined whether birth asphyxia measured by the pH of the blood in the umbilical artery cord was associated with childhood ADHD. A population-based cohort of 295 687 children born in Finland between 1991 and 2002 was followed until December 31, 2007. ADHD was identified by the International Classification of Diseases, 10th edition, as a diagnosis of hyperkinetic disorder. We examined the risk of ADHD with varying pH values using Cox regression, taking time trends into consideration. When compared to the reference group, a pH value below 7.10 was significantly associated with an increased risk of ADHD. The strongest risks were observed among children with a pH value value did not contribute much to the risk among children with an Apgar score of 0-3. Birth asphyxia, defined by low pH value, may predict an increased risk of ADHD in childhood. The association between the pH value and ADHD was homogenous when stratified by gestational age and the Apgar score. ©2017 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

pH sensing and regulation in cancer.

Science.gov (United States)

Damaghi, Mehdi; Wojtkowiak, Jonathan W; Gillies, Robert J

2013-12-17

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 pHi, 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). In this review, we will discuss some of the major players in proton sensing at the plasma membrane and their downstream consequences in cancer cells and how these pH-mediated changes affect processes such as migration and metastasis. The complex mechanisms by which they transduce acid pH signals to the cytoplasm and nucleus are not well understood. However, there is evidence that expression of proton-sensing GPCRs such as GPR4, TDAG8, and OGR1 can regulate aspects of tumorigenesis and invasion, including cofilin and talin regulated actin (de-)polymerization. Major mechanisms for maintenance of pHi homeostasis include monocarboxylate, bicarbonate, and proton transporters. Notably, there is little evidence suggesting a link between their activities and those of the extracellular H(+)-sensors, suggesting a mechanistic disconnect between intra- and extracellular pH. Understanding the mechanisms of pH sensing and regulation may lead to novel and informed therapeutic strategies that can target acidosis, a common physical hallmark of solid tumors.

PH Measurements of the Brain Using Phosphorus Magnetic Resonance Spectroscopy (31PMRS) in Healthy Men – Comparison of Two Analysis Methods

International Nuclear Information System (INIS)

Cichocka, Monika; Kozub, Justyna; Urbanik, Andrzej

2015-01-01

Intracellular pH provides information on homeostatic mechanisms in neurons and glial cells. The aim of this study was to define pH of the brain of male volunteers using phosphorus magnetic resonance spectroscopy ( 31 PMRS) and to compare two methods of calculating this value. In this study, 35 healthy, young, male volunteers (mean age: 25 years) were examined by 31 PMRS in 1.5 T MR system (Signa Excite, GE). The FID CSI (Free Induction Decay Chemical Shift Imaging) sequence was used with the following parameters: TR=4000 ms, FA=90°, NEX=2. Volume of interest (VOI) was selected depending on the size of the volunteers’ brain (11–14 cm 3 , mean 11.53 cm 3 ). Raw data were analyzed using SAGE (GE) software. Based on the chemical shift of peaks in the 31 PMRS spectrum, intracellular pH was calculated using two equations. In both methods the mean pH was slightly alkaline (7.07 and 7.08). Results were compared with a t-test. Significant difference (p<0.05) was found between these two methods. The 31 PMRS method enables non-invasive in vivo measurements of pH. The choice of the calculation method is crucial for computing this value. Comparing the results obtained by different teams can be done in a fully credible way only if the calculations were performed using the same formula

PH- Mapping Of Prepubertal Skin Of Indian Subjects

Directory of Open Access Journals (Sweden)

Gupta A B

1995-01-01

Full Text Available PH- mapping of skin was made by measuring the skin surface pH in 61 normal Indian subjects (35M, 26F in the prepubertal age group at 21 different sites from scalp to sole at an ambient temperature 25-32C and a relative humidity 60-65%. The pH values at axilla, umbilicus, palm, fingerfolds, foot, sole, and cheek were found to be consistently higher than those at scalp, forehead, retroauricular folds, antecubital and popliteal fossae, anterior arm, anterior the mean pH of male skin appeared to be lower than that of female. The highest pH recorded was in axilla (5.98 for male, 6.00 for female, irrespective of sex. The lowest value however was in anterior neck (4.59 for male and in antecubital fossa (4.83 for female. While the origin of the skin pH is yet to be definitely known, it was observed that a high density of both sweat gland and bacteria flora leads to a high pH, and high concentration of sebaceous gland and of bacterial flora to a lower pH.

Optic nerve pH and PO2

DEFF Research Database (Denmark)

Pedersen, Daniella B; Stefánsson, Einar; Kiilgaard, Jens Folke

2006-01-01

Earlier studies have demonstrated that carbonic anhydrase inhibitors (CAIs) increase optic nerve oxygen tension (ONPO(2)) in pigs. We hypothesized that the mechanism of this effect was either a CO(2) increase or a pH decrease in tissue and blood. To test this hypothesis we investigated and compared...... how optic nerve pH (ONpH) and ONPO(2) are affected by: (1) carbonic anhydrase inhibition; (2) respiratory acidosis, and (3) metabolic acidosis. We measured ONpH with a glass pH electrode and ONPO(2) with a polarographic oxygen electrode. One of the electrodes was placed in the vitreous cavity 0.5 mm...

The pH of beverages in the United States.

Science.gov (United States)

Reddy, Avanija; Norris, Don F; Momeni, Stephanie S; Waldo, Belinda; Ruby, John D

2016-04-01

Dental erosion is the chemical dissolution of tooth structure in the absence of bacteria when the environment is acidic (pH beverage's erosive potential. In addition, citrate chelation of calcium ions may contribute to erosion at higher pH. The authors of this study determined the erosive potential measured by the pH of commercially available beverages in the United States. The authors purchased 379 beverages from stores in Birmingham, Alabama, and categorized them (for example, juices, sodas, flavored waters, teas, and energy drinks) and assessed their pH. They used a pH meter to measure the pH of each beverage in triplicate immediately after it was opened at a temperature of 25°C. The authors recorded the pH data as mean (standard deviation). Most (93%, 354 of 379) beverages had a pH of less than 4.0, and 7% (25 of 379) had a pH of 4.0 or more. Relative beverage erosivity zones based on studies of apatite solubility in acid indicated that 39% (149 of 379) of the beverages tested in this study were considered extremely erosive (pH beverages in the United States found that most are potentially erosive to the dentition. This study's findings provide dental clinicians and auxiliaries with information regarding the erosive potential of commercially available beverages. Specific dietary recommendations for the prevention of dental erosion may now be developed based on the patient's history of beverage consumption. Copyright © 2016 American Dental Association. Published by Elsevier Inc. All rights reserved.

Force measuring valve assemblies, systems including such valve assemblies and related methods

Science.gov (United States)

DeWall, Kevin George [Pocatello, ID; Garcia, Humberto Enrique [Idaho Falls, ID; McKellar, Michael George [Idaho Falls, ID

2012-04-17

Methods of evaluating a fluid condition may include stroking a valve member and measuring a force acting on the valve member during the stroke. Methods of evaluating a fluid condition may include measuring a force acting on a valve member in the presence of fluid flow over a period of time and evaluating at least one of the frequency of changes in the measured force over the period of time and the magnitude of the changes in the measured force over the period of time to identify the presence of an anomaly in a fluid flow and, optionally, its estimated location. Methods of evaluating a valve condition may include directing a fluid flow through a valve while stroking a valve member, measuring a force acting on the valve member during the stroke, and comparing the measured force to a reference force. Valve assemblies and related systems are also disclosed.

Uso de membranas de Nafion para a construção de sensores ópticos para medidas de pH Use of Nafion® membranes for the construction of optical sensors for pH measurements

Directory of Open Access Journals (Sweden)

Silvia Cristina Lopes Pinheiro

2005-10-01

Full Text Available The behaviour of Nafion® polymeric membranes containing acid-base dyes, bromothymol blue (BB and methyl violet (MV, were studied aiming at constructing an optical sensor for pH measurement. BB revealed to be inadequate for developing sensing phases due to the electrostatic repulsion between negative groups of their molecules and the negative charge of the sulfonate group of the Nafion®, which causes leaching of the dye from the membrane. On the other hand, MV showed to be suitable due to the presence of positive groups in its structure. The membrane prepared from a methanolic solution whose Nafion®/dye molar ratio was 20 presented the best analytical properties, changing its color from green to violet in the pH range from 0.6 to 3.0. The membrane can be prepared with good reproducibility, presenting durability of ca. 6 months and response time of 22 s, making possible its use for pH determination in flow analysis systems.

PH5 for integrating and archiving different data types

Science.gov (United States)

Azevedo, Steve; Hess, Derick; Beaudoin, Bruce

2016-04-01

PH5 is IRIS PASSCAL's file organization of HDF5 used for seismic data. The extensibility and portability of HDF5 allows the PH5 format to evolve and operate on a variety of platforms and interfaces. To make PH5 even more flexible, the seismic metadata is separated from the time series data in order to achieve gains in performance as well as ease of use and to simplify user interaction. This separation affords easy updates to metadata after the data are archived without having to access waveform data. To date, PH5 is currently used for integrating and archiving active source, passive source, and onshore-offshore seismic data sets with the IRIS Data Management Center (DMC). Active development to make PH5 fully compatible with FDSN web services and deliver StationXML is near completion. We are also exploring the feasibility of utilizing QuakeML for active seismic source representation. The PH5 software suite, PIC KITCHEN, comprises in-field tools that include data ingestion (e.g. RefTek format, SEG-Y, and SEG-D), meta-data management tools including QC, and a waveform review tool. These tools enable building archive ready data in-field during active source experiments greatly decreasing the time to produce research ready data sets. Once archived, our online request page generates a unique web form and pre-populates much of it based on the metadata provided to it from the PH5 file. The data requester then can intuitively select the extraction parameters as well as data subsets they wish to receive (current output formats include SEG-Y, SAC, mseed). The web interface then passes this on to the PH5 processing tools to generate the requested seismic data, and e-mail the requester a link to the data set automatically as soon as the data are ready. PH5 file organization was originally designed to hold seismic time series data and meta-data from controlled source experiments using RefTek data loggers. The flexibility of HDF5 has enabled us to extend the use of PH5 in several

Critical review of pH sensing with optical fibers

Science.gov (United States)

Baldini, Francesco

1999-02-01

The chemical parameter most investigated with optical fibers is doubtless pH. The first pH optical fiber sensor was described in 1980. Since then, more than one hundred and twenty original papers describing different pH sensors have been published, based on absorption-based indicators on fluorophores. Such interest is perfectly justified, since pH detection is essential in many fields of application, ranging from the environment and medicine to industry and process control. Moreover, pH transduction can be used for measuring different chemical species, such as carbon dioxide, ammonia and pesticides. Notwithstanding the great number of prototypes realized in different laboratories all over the world, only a few products are available on the market. A critical analysis of the state of art in pH sensing using optical fibers is described, outlining the advantages and disadvantages of an optical approach.

Soil pH mapping with an on-the-go sensor.

Science.gov (United States)

Schirrmann, Michael; Gebbers, Robin; Kramer, Eckart; Seidel, Jan

2011-01-01

Soil pH is a key parameter for crop productivity, therefore, its spatial variation should be adequately addressed to improve precision management decisions. Recently, the Veris pH Manager™, a sensor for high-resolution mapping of soil pH at the field scale, has been made commercially available in the US. While driving over the field, soil pH is measured on-the-go directly within the soil by ion selective antimony electrodes. The aim of this study was to evaluate the Veris pH Manager™ under farming conditions in Germany. Sensor readings were compared with data obtained by standard protocols of soil pH assessment. Experiments took place under different scenarios: (a) controlled tests in the lab, (b) semicontrolled test on transects in a stop-and-go mode, and (c) tests under practical conditions in the field with the sensor working in its typical on-the-go mode. Accuracy issues, problems, options, and potential benefits of the Veris pH Manager™ were addressed. The tests demonstrated a high degree of linearity between standard laboratory values and sensor readings. Under practical conditions in the field (scenario c), the measure of fit (r(2)) for the regression between the on-the-go measurements and the reference data was 0.71, 0.63, and 0.84, respectively. Field-specific calibration was necessary to reduce systematic errors. Accuracy of the on-the-go maps was considerably higher compared with the pH maps obtained by following the standard protocols, and the error in calculating lime requirements was reduced by about one half. However, the system showed some weaknesses due to blockage by residual straw and weed roots. If these problems were solved, the on-the-go sensor investigated here could be an efficient alternative to standard sampling protocols as a basis for liming in Germany.

Next Generation Qualification: Nanometrics T120PH Seismometer Evaluation

Energy Technology Data Exchange (ETDEWEB)

Merchant, Bion J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Slad, George William [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-10-01

Sandia National Laboratories has tested and evaluated three seismometers, the Trillium 120PH, manufactured by Nanometrics. These seismometers measure broadband ground velocity using a UVW configuration with feedback control in a mechanically levelled borehole package. The purpose of the seismometer evaluation was to determine a measured sensitivity, response, self- noise, dynamic range, and self-calibration ability. The Nanometrics Trillium 120PH seismometers are being evaluated for the U.S. Air Force as part of their Next Generation Qualification effort.

Nanowire-templated microelectrodes for high-sensitivity pH detection

DEFF Research Database (Denmark)

Antohe, V.A.; Radu, Adrian; Mátéfi-Tempfli, Mária

2009-01-01

A highly sensitive pH capacitive sensor has been designed by confined growth of vertically aligned nanowire arrays on interdigited microelectrodes. The active surface of the device has been functionalized with an electrochemical pH transducer (polyaniline). We easily tune the device features...... by combining lithographic techniques with electrochemical synthesis. The reported electrical LC resonance measurements show considerable sensitivity enhancement compared to conventional capacitive pH sensors realized with microfabricated interdigited electrodes. The sensitivity can be easily improved...

Chemical Composition and Evaluation of Nicotine, Tobacco Alkaloids, pH and Selected Flavors in e-Cigarette Cartridges and Refill Solutions

Science.gov (United States)

Lisko, Joseph G.; Tran, Hang; Stanfill, Stephen B.; Blount, Benjamin C.; Watson, Clifford H.

2015-01-01

Introduction Electronic cigarette (e-cigarette) use is increasing dramatically in developed countries, but little is known about these rapidly evolving products. This study analyzed and evaluated the chemical composition including nicotine, tobacco alkaloids, pH and flavors in 36 e-liquids brands from four manufacturers. Methods We determined the concentrations of nicotine, alkaloids, and select flavors and measured pH in solutions used in e-cigarettes. E-cigarette products were chosen based upon favorable consumer approval ratings from online review websites. Quantitative analyses were performed using strict quality assurance/quality control (QC) validated methods previously established by our lab for the measurement of nicotine, alkaloids, pH and flavors. Results Three-quarters of the products contained lower measured nicotine levels than the stated label values (6% - 42% by concentration). The pH for e-liquids ranged from 5.1 – 9.1. Minor tobacco alkaloids were found in all samples containing nicotine, and their relative concentrations varied widely among manufacturers. A number of common flavor compounds were analyzed in all e-liquids. Conclusions Free nicotine levels calculated from the measurement of pH correlated with total nicotine content. The direct correlation between the total nicotine concentration and pH suggests that the alkalinity of nicotine drives the pH of e-cigarette solutions. A higher percentage of nicotine exists in the more absorbable free form as total nicotine concentration increases. A number of products contained tobacco alkaloids at concentrations that exceed U.S. Pharmacopeia limits for impurities in nicotine used in pharmaceutical and food products. PMID:25636907

Optic nerve pH and PO2

DEFF Research Database (Denmark)

Pedersen, Daniella B; Stefánsson, Einar; Kiilgaard, Jens Folke

2006-01-01

Earlier studies have demonstrated that carbonic anhydrase inhibitors (CAIs) increase optic nerve oxygen tension (ONPO(2)) in pigs. We hypothesized that the mechanism of this effect was either a CO(2) increase or a pH decrease in tissue and blood. To test this hypothesis we investigated and compared...... how optic nerve pH (ONpH) and ONPO(2) are affected by: (1) carbonic anhydrase inhibition; (2) respiratory acidosis, and (3) metabolic acidosis. We measured ONpH with a glass pH electrode and ONPO(2) with a polarographic oxygen electrode. One of the electrodes was placed in the vitreous cavity 0.5 mm...... over the optic nerve in the eyes of domestic pigs....

Evaluation of the relation between lipid coat, transepidermal water loss, and skin pH.

Science.gov (United States)

Algiert-Zielińska, Barbara; Batory, Mirella; Skubalski, Janusz; Rotsztejn, Helena

2017-11-01

The epidermis is an epidermal barrier which accumulates lipid substances and participates in skin moisturizing. An evaluation of the epidermal barrier efficiency can be made, among others, by the measurement of the following values: the lipid coat, the transepidermal water loss (TEWL) index, and pH. The study involved 50 Caucasian, healthy women aged 19-35 years (mean 20.56). Measurements were made using Courage & Khazaka Multi Probe Adapter MPA 580: Tewameter TM 300, pH-Meter PH 905, Sebumeter SM 815. The areas of measurements included forehead, nose, left cheek, right cheek, chin, and thigh. In the T-zone, the lipid coat was in the range between 0 and 270 μg/cm 2 (mean 128 μg/cm 2 ), TEWL between 1 and 55 g/m 2 /h (mean 11.1 g/m 2 /h), and pH 4.0-5.6 (mean 5.39). Lower values of the lipid coat up to 100 μg/cm 2 were accompanied by TEWL greater than 30 g/m 2 /h and less acidic pH of 5.6-9.0. In the U-zone the range of lipid coat was up to 200 μg/cm 2 (mean 65.2 μg/cm 2 ), the skin pH remained 4.0-5.6 (mean 5.47), and TEWL was in the range between 1 and 20 g/m 2 /h (mean 8.7 g/m 2 /h). Lower values of the lipid coat up to 100 μg/cm 2 were accompanied by TEWL between 1 and 20 g/m 2 /h and less acidic pH of 5.6-9.0. High values of the lipid coat between 180 and 200 μg/cm 2 were connected with TEWL of 1-15 g/m 2 /h. On the skin of the thigh, we observed a very thin lipid coat - 35 μg/cm 2 (mean 5.6 μg/cm 2 ), pH (mean 5.37), and TEWL (mean 8.5 g/m 2 /h) were considered by us to be within regular limits. In the T-zone, a thinner lipid coat resulted in relatively high TEWL and pH levels changing toward alkaline. In the U-zone, thinner lipid coat was accompanied by lower TEWL and pH changing toward alkaline. We also observed that lower values of lipid coat up to 100 μg/cm 2 were associated with higher pH values ranging toward the basic character pH 5.6-9.0). © 2017 The International Society of Dermatology.

A genetically-encoded chloride and pH sensor for dissociating ion dynamics in the nervous system.

Science.gov (United States)

Raimondo, Joseph V; Joyce, Bradley; Kay, Louise; Schlagheck, Theresa; Newey, Sarah E; Srinivas, Shankar; Akerman, Colin J

2013-01-01

Within the nervous system, intracellular Cl(-) and pH regulate fundamental processes including cell proliferation, metabolism, synaptic transmission, and network excitability. Cl(-) and pH are often co-regulated, and network activity results in the movement of both Cl(-) and H(+). Tools to accurately measure these ions are crucial for understanding their role under physiological and pathological conditions. Although genetically-encoded Cl(-) and pH sensors have been described previously, these either lack ion specificity or are unsuitable for neuronal use. Here we present ClopHensorN-a new genetically-encoded ratiometric Cl(-) and pH sensor that is optimized for the nervous system. We demonstrate the ability of ClopHensorN to dissociate and simultaneously quantify Cl(-) and H(+) concentrations under a variety of conditions. In addition, we establish the sensor's utility by characterizing activity-dependent ion dynamics in hippocampal neurons.

Field Performance of ISFET based Deep Ocean pH Sensors

Science.gov (United States)

Branham, C. W.; Murphy, D. J.

2017-12-01

Historically, ocean pH time series data was acquired from infrequent shipboard grab samples and measured using labor intensive spectrophotometry methods. However, with the introduction of robust and stable ISFET pH sensors for use in ocean applications a paradigm shift in the methods used to acquire long-term pH time series data has occurred. Sea-Bird Scientific played a critical role in the adoption this new technology by commercializing the SeaFET pH sensor and float pH Sensor developed by the MBARI chemical sensor group. Sea-Bird Scientific continues to advance this technology through a concerted effort to improve pH sensor accuracy and reliability by characterizing their performance in the laboratory and field. This presentation will focus on calibration of the ISFET pH sensor, evaluate its analytical performance, and validate performance using recent field data.

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

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

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

Inhibitors of acid secretion can benefit gastric wound repair independent of luminal pH effects on the site of damage

Science.gov (United States)

Demitrack, Elise S; Aihara, Eitaro; Kenny, Susan; Varro, Andrea; Montrose, Marshall H

2012-01-01

Background and aims The authors’ goal was to measure pH at the gastric surface (pHo) to understand how acid secretion affects the repair of microscopic injury to the gastric epithelium. Methods Microscopic gastric damage was induced by laser light, during confocal/two-photon imaging of pH-sensitive dyes (Cl-NERF, BCECF) that were superfused over the mucosal surface of the exposed gastric corpus of anaesthetised mice. The progression of repair was measured in parallel with pHo. Experimental conditions included varying pH of luminal superfusates, and using omeprazole (60 mg/kg ip) or famotidine (30 mg/kg ip) to inhibit acid secretion. Results Similar rates of epithelial repair and resting pHo values (~pH 4) were reported in the presence of luminal pH 3 or pH 5. Epithelial repair was unreliable at luminal pH 2 and pHo was lower (2.5±0.2, P pH 3). Epithelial repair was slower at luminal pH 7 and pHo was higher (6.4±0.1, PpH 3 or pH 7, omeprazole reduced maximal damage size and accelerated epithelial repair, although only at pH 3 did omeprazole further increase surface pH above the level caused by imposed damage. At luminal pH 7, famotidine also reduced maximal damage size and accelerated epithelial repair. Neither famotidine nor omeprazole raised plasma gastrin levels during the time course of the experiments. Conclusions Epithelial repair in vivo is affected by luminal pH variation, but the beneficial effects of acutely blocking acid secretion extend beyond simply raising luminal and/or surface pH. PMID:21997560

Portable instrumentation for quantitatively measuring radioactive surface contaminations, including 90Sr

International Nuclear Information System (INIS)

Brodzinski, R.L.

1983-10-01

In order to measure the effectiveness of decontamination efforts, a quantitative analysis of the radiocontamination is necessary, both before and after decontamination. Since it is desirable to release the decontaminated material for unrestricted use or disposal, the assay equipment must provide adequate sensitivity to measure the radioactivity at or below the release limit. In addition, the instrumentation must be capable of measuring all kinds of radiocontaminants including fission products, activation products, and transuranic materials. Finally, the survey instrumentation must be extremely versatile in order to assay the wide variety of contaminated surfaces in many environments, some of which may be extremely hostile or remote. This communication describes the development and application of portable instrumentation capable of quantitatively measuring most transuranics, activation products, and fission products, including 90 Sr, on almost any contaminated surface in nearly any location

Evaluation of Macerating Pectinase Enzyme Activity under Various Temperature, pH and Ethanol Regimes

Directory of Open Access Journals (Sweden)

Andrew G. Reynolds

2018-02-01

Full Text Available The polygalacturonase (PGU, hemicellulase (mannanase and protease enzyme activities in commercial macerating, pectinase-enzyme preparations commonly used by wineries in Ontario (Scottzyme Color X and Color Pro were measured under various simulated process conditions (temperature, pH, and ethanol concentration. Treatments included three temperatures (15, 20 and 30 °C; pH = 3.0, 3.5, 4.0 and 5.0; ethanol = 0%, four pH levels (3.0, 3.5, 4.0 and 5.0; temperature = 15, 20, 30 and 50 °C; ethanol = 0%, and four ethanol concentrations ((2.5, 5, 7.5 and 10%; temperature = 20 °C and pH = 3.5. Polygalacturonase enzyme activity in Color X increased linearly with temperature at all pH levels, and increased with pH at all temperature regimes. Polygalacturonase activity decreased with increasing ethanol. Color X mannanase activity increased with temperatures between 15 and 40 °C, and decreased with increased pH between 3.0 and 5.0. Response of mannanase to ethanol was cubic with a sharp decrease between 8 and 10% ethanol. Protease activity increased linearly with temperatures between 20 and 40 °C. These data suggest that the PGU, mannanase and protease components in these enzyme products provide sufficient activities within the ranges of pH, temperature, and ethanol common during the initial stages of red wine fermentations, although low must temperatures (<20 °C and presence of ethanol would likely lead to sub-optimal enzyme activities.

LED-CT Scan for pH Distribution on a Cross-Section of Cell Culture Medium.

Science.gov (United States)

Higashino, Nobuya; Takayama, Toshio; Ito, Hiroaki; Horade, Mitsuhiro; Yamaguchi, Yasutaka; Dylan Tsai, Chia-Hung; Kaneko, Makoto

2018-01-11

In cell culture, the pH of the culture medium is one of the most important conditions. However, the culture medium may have non-uniform pH distribution due to activities of cells and changes in the environment. Although it is possible to measure the pH distribution with an existing pH meter using distributed electrodes, the method involves direct contact with the medium and would greatly increase the risk of contamination. Here in this paper, we propose a computed tomography (CT) scan for measuring pH distribution using the color change of phenol red with a light-emitting diode (LED) light source. Using the principle of CT scan, we can measure pH distribution without contacting culture medium, and thus, decrease the risk of contamination. We have developed the device with a LED, an array of photo receivers and a rotation mechanism. The system is firstly calibrated with different shapes of wooden objects that do not pass light, we succeeded in obtaining their 3D topographies. The system was also used for measuring a culture medium with two different pH values, it was possible to obtain a pH distribution that clearly shows the boundary.

The enhanced cyan fluorescent protein: a sensitive pH sensor for fluorescence lifetime imaging.

Science.gov (United States)

Poëa-Guyon, Sandrine; Pasquier, Hélène; Mérola, Fabienne; Morel, Nicolas; Erard, Marie

2013-05-01

pH is an important parameter that affects many functions of live cells, from protein structure or function to several crucial steps of their metabolism. Genetically encoded pH sensors based on pH-sensitive fluorescent proteins have been developed and used to monitor the pH of intracellular compartments. The quantitative analysis of pH variations can be performed either by ratiometric or fluorescence lifetime detection. However, most available genetically encoded pH sensors are based on green and yellow fluorescent proteins and are not compatible with multicolor approaches. Taking advantage of the strong pH sensitivity of enhanced cyan fluorescent protein (ECFP), we demonstrate here its suitability as a sensitive pH sensor using fluorescence lifetime imaging. The intracellular ECFP lifetime undergoes large changes (32 %) in the pH 5 to pH 7 range, which allows accurate pH measurements to better than 0.2 pH units. By fusion of ECFP with the granular chromogranin A, we successfully measured the pH in secretory granules of PC12 cells, and we performed a kinetic analysis of intragranular pH variations in living cells exposed to ammonium chloride.

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.

Layer configurations comparison of bilayer-films for EGFET pH sensor application

Science.gov (United States)

Rahman, R. A.; Zulkefle, M. A.; Yusof, K. A.; Abdullah, W. F. H.; Rusop, M.; Herman, S. H.

2018-05-01

The comparison between bilayer configurations were presented in this paper. TiO2 and ZnO layer configurations were manipulated in order to investigate which configuration produce highest sensing performance to be applied as EGFET pH sensor. Both of the materials were deposited together as the bilayer film. The configurations were manipulated between TiO2/ZnO and ZnO/TiO2. ITO was used as the substrate in this study and both of the materials were deposited by using sol-gel spin coating technique. After deposition process, these bilayer film then undergone for EGFET pH sensor measurement and physical characterization. The EGFET pH sensor measurement was done by dipping the fabricated bilayer film into three different pH values, which is pH4, pH7 and pH10. Bilayer film act as the pH-sensitive membrane, which connected to the commercial metal-oxide semiconductor FET (MOSFET). This MOSFET was connected to the interfacing circuit. Voltage output obtained were recorded and the graph was plotted by using the data recorded. Based on the EGFET pH sensor measurement, TiO2/ZnO bilayer film exhibit higher sensing performance, compared with ZnO/TiO2. TiO2/ZnO bilayer film produced 53.10 mV/pH with the linearity value of 0.9913. Afterwards, fabricated bilayer films then were characterized with AFM to explore their surface roughness and surface topography behavior.

The potential effects of pH and buffering capacity on dental erosion.

Science.gov (United States)

Owens, Barry M

2007-01-01

Soft drink pH (initial pH) has been shown to be a causative factor--but not necessarily the primary initiating factor--of dental erosion. The titratable acidity or buffering capacity has been acknowledged as playing a significant role in the etiology of these lesions. This in vitro study sought to evaluate five different soft drinks (Coca-Cola Classic, Diet Coke, Gatorade sports drink, Red Bull high-energy drink, Starbucks Frappucino coffee drink) and tap water (control) in terms of initial pH and buffering capacity. Initial pH was measured in triplicate for the six beverages. The buffering capacity of each beverage was assessed by measuring the weight (in grams) of 0.10 M sodium hydroxide necessary for titration to pH levels of 5.0, 6.0, 7.0, and 8.3. Coca-Cola Classic produced the lowest mean pH, while Starbucks Frappucino produced the highest pH of any of the drinks except for tap water. Based on statistical analysis using ANOVA and Fisher's post hoc tests at a P Starbucks Frappucino.

Measurement of Rapid Amiloride-Dependent pH Changes at the Cell Surface Using a Proton-Sensitive Field-Effect Transistor.

Science.gov (United States)

Schaffhauser, Daniel; Fine, Michael; Tabata, Miyuki; Goda, Tatsuro; Miyahara, Yuji

2016-03-30

We present a novel method for the rapid measurement of pH fluxes at close proximity to the surface of the plasma membrane in mammalian cells using an ion-sensitive field-effect transistor (ISFET). In conjuction with an efficient continuous superfusion system, the ISFET sensor was capable of recording rapid changes in pH at the cells' surface induced by intervals of ammonia loading and unloading, even when using highly buffered solutions. Furthermore, the system was able to isolate physiologically relevant signals by not only detecting the transients caused by ammonia loading and unloading, but display steady-state signals as would be expected by a proton transport-mediated influence on the extracellular proton-gradient. Proof of concept was demonstrated through the use of 5-(N-ethyl-N-isopropyl)amiloride (EIPA), a small molecule inhibitor of sodium/hydrogen exchangers (NHE). As the primary transporter responsible for proton balance during cellular regulation of pH, non-electrogenic NHE transport is notoriously difficult to detect with traditional methods. Using the NHE positive cell lines, Chinese hamster ovary (CHO) cells and NHE3-reconstituted mouse skin fibroblasts (MSF), the sensor exhibited a significant response to EIPA inhibition, whereas NHE-deficient MSF cells were unaffected by application of the inhibitor.

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.

Microelectrode characterization of coral daytime interior pH and carbonate chemistry.

Science.gov (United States)

Cai, Wei-Jun; Ma, Yuening; Hopkinson, Brian M; Grottoli, Andréa G; Warner, Mark E; Ding, Qian; Hu, Xinping; Yuan, Xiangchen; Schoepf, Verena; Xu, Hui; Han, Chenhua; Melman, Todd F; Hoadley, Kenneth D; Pettay, D Tye; Matsui, Yohei; Baumann, Justin H; Levas, Stephen; Ying, Ye; Wang, Yongchen

2016-04-04

Reliably predicting how coral calcification may respond to ocean acidification and warming depends on our understanding of coral calcification mechanisms. However, the concentration and speciation of dissolved inorganic carbon (DIC) inside corals remain unclear, as only pH has been measured while a necessary second parameter to constrain carbonate chemistry has been missing. Here we report the first carbonate ion concentration ([CO3(2-)]) measurements together with pH inside corals during the light period. We observe sharp increases in [CO3(2-)] and pH from the gastric cavity to the calcifying fluid, confirming the existence of a proton (H(+)) pumping mechanism. We also show that corals can achieve a high aragonite saturation state (Ωarag) in the calcifying fluid by elevating pH while at the same time keeping [DIC] low. Such a mechanism may require less H(+)-pumping and energy for upregulating pH compared with the high [DIC] scenario and thus may allow corals to be more resistant to climate change related stressors.

Drilling and the associated drillhole measurements of the pilot hole ONK-PH5

International Nuclear Information System (INIS)

Oehberg, A.; Hirvonen, H.; Jurvanen, T.; Kemppainen, K.; Mustonen, A.; Niemonen, J.; Poellaenen, J.; Rouhiainen, P.; Rautio, T.

2006-09-01

The construction of the ONKALO access tunnel started in September 2004 at Olkiluoto. Most of the investigations related to the construction of the access tunnel aim to ensure successful excavations, reinforcement and sealing. Pilot holes are drillholes, which are core drilled along the tunnel profile. The length of the pilot holes typically varies from several tens of metres to a couple of hundred metres. The pilot holes are aimed to confirm the quality of the rock mass for tunnel construction, and in particular to identify water conductive fractured zones and to provide information that could result in modifications of the existing construction plans. The pilot hole ONK-PH5 was drilled from chainage 991.4 to chainage 1194 in January 2006. The length of the hole is 202.64 m and the vertical depth of the hole from zero level is about 88.2-107.5 m. The aim during the drilling work was to orient core samples as much as possible. The deviation of the drillhole was measured during and after the drilling phase. One steering operation by wedging was made at the hole depth of 128.58 metres. Electric conductivity was measured from the collected returning water samples. Logging of the core samples included the following parameters: lithology, foliation, fracturing, fracture frequency, RQD, fractured zones, core loss and weathering. The rock mechanical logging was based on Q-classification. The tests to determine rock strength and deformation properties were made with a Rock Tester-equipment. Due to high inflow (c. 200 L/min) mainly from the depth section 56-58 metres no geophysical surveys were carried out in the hole. Flow logging was carried out only from 58 metres to the bottom of the hole. Difference Flow method was used for the determination of hydraulic conductivity in fractures and fractured zones in the drillhole. The overlapping i.e. the detailed flow logging mode was used. The flow logging was performed with 0.5 m section length and with 0.1 m depth increment. Flow

Effect of pH on sludge composting

International Nuclear Information System (INIS)

Hashimoto, Shoji; Watanabe, Hiromasa; Nishimura, Koichi; Kawakami, Waichiro

1984-01-01

The effect of pH on composting of irradiated sewage sludge was discussed. Inorganic materials, such as activated alumina, Kanuma-soil, and Akadama-soil, were used as bulking agents. Na 2 CO 3 was used as a pH adjuster. The fermentations were done isothermally at the optimum temperature, 50 0 C. The rate of CO 2 evolution increased initially with time, and then, decreased. The peak value of CO 2 evolution and the time to attain the peak varied by the addition of Na 2 CO 3 . When Kanuma-soil was used as the bulking agent, for example, the peak value became larger as the amount of Na 2 CO 3 was increased to 1.0 % and became smaller over this value. From pH measurements, it was found that the optimum pH for fermentation was ranged from 6 to 8 when activated alumina was used. When other bulking agents were used, the maximum value of CO 2 evolution rate was obtained at pH 7 to 8.5. The peak value and the peak time also varied by the addition of NH 3 in the aeration gas. (author)

A Simple Technique for Determining the pH of Whole Cigarette Smoke

Directory of Open Access Journals (Sweden)

Dong J

2014-12-01

Full Text Available A new technique has been developed to determine the pH of whole cigarette smoke. In this technique, whole smoke from ten cigarettes was trapped in 300 mL water containing 1% (w/v sodium chloride and the pH was determined on the resulting aqueous suspension of cigarette smoke. Two impingers with an extra coarse porosity fritted disc were used to dispense the smoke in the aqueous trapping medium. Cigarettes were smoked on a 20-port Borgwaldt RM 20/CS smoking machine using modified FTC (Federal Trade Commission conditions. The puff volume was adjusted to take a 35 mL puff as measured through the cigarette and the collection traps. This new technique accounts for the contributions to smoke pH from both the vapor phase and the particulate phase of smoke. The repeatability of this new technique was determined on eighteen replicates of a commercially available non-menthol, filter cigarette. Each measurement was done on a different day to check for a possible drift in pH with time. The mean pH value for the chosen sample was found to be 4.97 with a standard deviation of 0.07 pH units. The smoke pH values for over 150 commercially available cigarette brands with a variety of “tar” levels were determined. The smoke pH values had a range from 4.6 to 5.5, with an average of 4.79 and a maximum standard deviation of 0.10 pH units. An experimental flue cured cigarette had a smoke pH of around 5.0, while an experimental Burley cigarette had a smoke pH of 5.4. No correlation between smoke pH and “tar” or total particulate matter (TPM and between pH and nicotine levels was found. The purpose of the present study was to develop a practical, relatively simple laboratory method to measure the pH of a water solution of whole smoke, and was not intended to reflect, or have direct relevance for any biochemical or biological phenomena such as inhalability of smoke, flavor perception, nicotine ab-sorption, etc.”

Some effects of pH on iodine volatility in containment

International Nuclear Information System (INIS)

Ashmore, C.B.; Gwyther, J.R.; Sims, H.E.

1994-01-01

The behaviour of iodine in containment in the event of an accident involving fission product release would be strongly dependent on pH. High pH leads to a lower rate of radiolytic oxidation and in alkaline conditions the thermally stable form is IO 3 - . Much of the work on effects of pH on radiolytic oxidation reported in the literature may be erroneous or misleading because of postirradiation reaction and in this report some new experiments are described which were designed to overcome these problems involving sparged irradiated solutions of CsI spiked with 131 I. The rate of radiolytic oxidation has been measured as a function of pH between pH 4.6 and pH 9 and iodide concentrations between 10 -4 and 10 -6 mol dm -3 . Also discussed in the paper are factors which can affect the pH of the sump water and the effects of high pH in sprays. It is concluded that high pH is beneficial and it is important not only to achieve high pH but to maintain it. (author). 10 refs., 1 tab., 6 figs

Tumor blood flow and pH changes after glucose administration

International Nuclear Information System (INIS)

Thistlethwaite, A.J.; Tupchong, L.; Leeper, D.B.

1987-01-01

The authors used a laser doppler technique to correlate blood flow changes with pH changes in human tumors after glucose ingestion. Three PTs with large superficial tumors ingested 100 gm glucose. A 21g needle pH electrode (Micro-electrodes, Inc.) and a 21g ''Laserflo'' fiberoptic laser doppler blood flow probe (TSI, Minneapolis, MN) were used at the same location. Blood glucose was measured by finger stick every 7.5 min. One PT with a squamous cell CA with extensive necrosis had only a small increase in blood glucose and an increase in tumor pH. Blood flow readings were within 6.4-18.4ml/100g/min. Another PT with a squamous CA had a drop in tumor pH (7.46 to 7.05) as blood glucose increased from 85 to 137 mg/dl by 55 min. Blood flow remained in a range of 7.7-13.8 ml/100g/min with a mean of 11.4. The third PT with a sarcoma had tumor pH and blood glucose measurements on two occasions, with similar results. Blood glucose rose from approx. 100 to 150 mg/dl by 52.5 min with a drop in tumor pH from approx. 7.4 to 7.25. On the second trial, tumor blood flow was measured and, while erratic (6.4-24.9ml/100g/min), decreased by approx. 50%. These preliminary data show that the laser doppler blood flow technique is quite sensitive to movement artifact and interference by free hemoglobin. Currently, it is inconclusive whether blood flow is altered with blood glucose and tumor pH changes. Further studies may prove this to be a valuable tool in predicting tumor response to hyperthermia

Roughness and pH changes of enamel surface induced by soft drinks in vitro-applications of stylus profilometry, focus variation 3D scanning microscopy and micro pH sensor.

Science.gov (United States)

Fujii, Mie; Kitasako, Yuichi; Sadr, Alireza; Tagami, Junji

2011-01-01

This study aimed to evaluate enamel surface roughness (Ra) and pH before and after erosion by soft drinks. Enamel was exposed to a soft drink (cola, orange juice or green tea) for 1, 5 or 60 min; Ra was measured using contact-stylus surface profilometry (SSP) and non-contact focus variation 3D microscope (FVM). Surface pH was measured using a micro pH sensor. Data were analyzed at significance level of alpha=0.05. There was a significant correlation in Ra between SSP and FVM. FVM images showed no changes in the surface morphology after various periods of exposure to green tea. Unlike cola and orange juice, exposure to green tea did not significantly affect Ra or pH. A significant correlation was observed between surface pH and Ra change after exposure to the drinks. Optical surface analysis and micro pH sensor may be useful tools for non-damaging, quantitative assessment of soft drinks erosion on enamel.

A genetically-encoded chloride and pH sensor for dissociating ion dynamics in the nervous system

Science.gov (United States)

Raimondo, Joseph V.; Joyce, Bradley; Kay, Louise; Schlagheck, Theresa; Newey, Sarah E.; Srinivas, Shankar; Akerman, Colin J.

2013-01-01

Within the nervous system, intracellular Cl− and pH regulate fundamental processes including cell proliferation, metabolism, synaptic transmission, and network excitability. Cl− and pH are often co-regulated, and network activity results in the movement of both Cl− and H+. Tools to accurately measure these ions are crucial for understanding their role under physiological and pathological conditions. Although genetically-encoded Cl− and pH sensors have been described previously, these either lack ion specificity or are unsuitable for neuronal use. Here we present ClopHensorN—a new genetically-encoded ratiometric Cl− and pH sensor that is optimized for the nervous system. We demonstrate the ability of ClopHensorN to dissociate and simultaneously quantify Cl− and H+ concentrations under a variety of conditions. In addition, we establish the sensor's utility by characterizing activity-dependent ion dynamics in hippocampal neurons. PMID:24312004

A genetically-encoded chloride and pH sensor for dissociating ion dynamics in the nervous system

Directory of Open Access Journals (Sweden)

Joseph Valentino Raimondo

2013-11-01

Full Text Available Within the nervous system, intracellular Cl- and pH regulate fundamental processes including cell proliferation, metabolism, synaptic transmission and network excitability. Cl- and pH are often co-regulated, and network activity results in the movement of both Cl- and H+. Tools to accurately measure these ions are crucial for understanding their role under physiological and pathological conditions. Although genetically-encoded Cl- and pH sensors have been described previously, these either lack ion specificity or are unsuitable for neuronal use. Here we present ClopHensorN - a new genetically-encoded ratiometric Cl- and pH sensor that is optimized for the nervous system. We demonstrate the ability of ClopHensorN to dissociate and simultaneously quantify Cl- and H+ concentrations under a variety of conditions. In addition, we establish the sensor’s utility by characterizing activity-dependent ion dynamics in hippocampal neurons.

Voltammetric pH sensing using carbon electrodes: glassy carbon behaves similarly to EPPG.

Science.gov (United States)

Lu, Min; Compton, Richard G

2014-09-21

Developing and building on recent work based on a simple sensor for pH determination using unmodified edge plane pyrolytic graphite (EPPG) electrodes, we present a voltammetric method for pH determination using a bare unmodified glassy carbon (GC) electrode. By exploiting the pH sensitive nature of quinones present on carbon edge-plane like sites within the GC, we show how GC electrodes can be used to measure pH. The electro-reduction of surface quinone groups on the glassy carbon electrode was characterised using cyclic voltammetry (CV) and optimised with square-wave voltammetry (SWV) at 298 K and 310 K. At both temperatures, a linear correlation was observed, corresponding to a 2 electron, 2 proton Nernstian response over the aqueous pH range 1.0 to 13.1. As such, unmodified glassy carbon electrodes are seen to be pH dependent, and the Nernstian response suggests its facile use for pH sensing. Given the widespread use of glassy carbon electrodes in electroanalysis, the approach offers a method for the near-simultaneous measurement and monitoring of pH during such analyses.

Comprehensive analysis of proteins of pH fractionated samples using monolithic LC/MS/MS, intact MW measurement and MALDI-QIT-TOF MS

Science.gov (United States)

Yoo, Chul; Patwa, Tasneem H.; Kreunin, Paweena; Miller, Fred R.; Huber, Christian G.; Nesvizhskii, Alexey I.; Lubman, David M.

2012-01-01

A comprehensive platform that integrates information from the protein and peptide levels by combining various MS techniques has been employed for the analysis of proteins in fully malignant human breast cancer cells. The cell lysates were subjected to chromatofocusing fractionation, followed by tryptic digestion of pH fractions for on-line monolithic RP-HPLC interfaced with linear ion trap MS analysis for rapid protein identification. This unique approach of direct analysis of pH fractions resulted in the identification of large numbers of proteins from several selected pH fractions, in which approximately 1.5 μg of each of the pH fraction digests was consumed for an analysis time of ca 50 min. In order to combine valuable information retained at the protein level with the protein identifications obtained from the peptide level information, the same pH fraction was analyzed using nonporous (NPS)-RP-HPLC/ESI-TOF MS to obtain intact protein MW measurements. In order to further validate the protein identification procedures from the fraction digest analysis, NPS-RP-HPLC separation was performed for off-line protein collection to closely examine each protein using MALDI-TOF MS and MALDI-quadrupole ion trap (QIT)-TOF MS, and excellent agreement of protein identifications was consistently observed. It was also observed that the comparison to intact MW and other MS information was particularly useful for analyzing proteins whose identifications were suggested by one sequenced peptide from fraction digest analysis. PMID:17206599

PhD supervisor-student relationship

Directory of Open Access Journals (Sweden)

FILIPE PRAZERES

2017-10-01

but also improve their coping skills, including critical thinking and problem-solving methods (5. The act of sharing knowledge and experiences can motivate the PhD students to persevere in their studies (10. When needed, supervisors should use their power of influence to increase the time that the student has available to devote to research while maintaining a part of their employment activities (health care‑related or not, since many PhD students are also full-time workers. Last but not least, supervisors and faculty members must encourage PhD students to pursue the available funding opportunities. Socioeconomic problems are known to be an issue for PhD students (5. Without the supervisor’s support – by dealing with PhD student’s emotions and personality –, research time, funding, and the student’s proactiviness, the doctoral journey may not attain success.

A ph sensor based on a flexible substrate

Science.gov (United States)

Huang, Wen-Ding

pH sensor is an essential component used in many chemical, food, and bio-material industries. Conventional glass electrodes have been used to construct pH sensors, however, have some disadvantages. Glass electrodes are easily affected by alkaline or HF solution, they require a high input impedance pH meter, they often exhibit a sluggish response. In some specific applications, it is also difficult to use glass electrodes for in vivo biomedical or food monitoring applications due to the difficulty of size miniaturization, planarization and polymerization based on current manufacturing technologies. In this work, we have demonstrated a novel flexible pH sensor based on low-cost sol-gel fabrication process of iridium oxide (IrOx) sensing film (IROF). A pair of flexible miniature IrOx/AgCl electrode generated the action potential from the solution by electrochemical mechanism to obtain the pH level of the reagent. The fabrication process including sol-gel, thermal oxidation, and the electro-plating process of the silver chloride (AgCl) reference electrode were reported in the work. The IrOx film was verified and characterized using electron dispersive analysis (EDAX), scanning electron microscope (SEM), and x-ray diffraction (XRD). The flexible pH sensor's performance and characterization have been investigated with different testing parameters such as sensitivity, response time, stability, reversibility, repeatability, selectivity and temperature dependence. The flexible IrOx pH sensors exhibited promising sensing performance with a near-Nernstian response of sensitivity which is between --51.1mV/pH and --51.7mV/pH in different pH levels ranging from 1.5 to 12 at 25°C. Two applications including gastroesophageal reflux disease (GERD) diagnosis and food freshness wireless monitoring using our micro-flexible IrOx pH sensors were demonstrated. For the GERD diagnosing system, we embedded the micro flexible pH sensor on a 1.2cmx3.8cm of the capsule size of wireless sensor

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.

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)

Development of a pH sensor using nanoporous nanostructures of NiO.

Science.gov (United States)

Ibupoto, Z H; Khun, K; Willander, M

2014-09-01

Glass is the conventional material used in pH electrodes to monitor pH in various applications. However, the glass-based pH electrode has some limitations for particular applications. The glass sensor is limited in the use of in vivo biomedical, clinical or food applications because of the brittleness of glass, its large size, the difficulty in measuring small volumes and the absence of deformation (inflexibility). Nanostructure-based pH sensors are very sensitive, reliable, fast and applicable towards in vivo measurements. In this study, nanoporous NiO nanostructures are synthesized on a gold-coated glass substrate by a hydrothermal route using poly(vinyl alcohol) (PVA) as a stabilizer. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were used for the morphological and crystalline studies. The grown NiO nanostructures are uniform and dense, and they possess good crystallinity. A pH sensor based on these NiO nanostructures was developed by testing the different pH values from 2-12 of phosphate buffered saline solution. The proposed pH sensor showed robust sensitivity of -43.74 ± 0.80 mV/pH and a quick response time of less than 10 s. Moreover, the repeatability, reproducibility and stability of the presented pH sensor were also studied.

Open-Source Low-Cost Wireless Potentiometric Instrument for pH Determination Experiments

Science.gov (United States)

Jin, Hao; Qin, Yiheng; Pan, Si; Alam, Arif U.; Dong, Shurong; Ghosh, Raja; Deen, M. Jamal

2018-01-01

pH determination is an essential experiment in many chemistry laboratories. It requires a potentiometric instrument with extremely low input bias current to accurately measure the voltage between a pH sensing electrode and a reference electrode. In this technology report, we propose an open-source potentiometric instrument for pH determination…

Intracellular pH distribution as a cell health indicator in Saccharomyces cerevisiae

DEFF Research Database (Denmark)

Aabo, Thomas; Glückstad, Jesper; Siegumfeldt, Henrik

2011-01-01

.d.(pHint)) to describe the internal pH distributions. The cellular pH distributional response to external stress such as heat has not previously been determined. In this study, the intracellular pH (pHi) and the s.d.(pHint) of Saccharomyces cerevisiae cells exposed to supralethal temperatures were measured using...

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.

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.

Homogeneous plate based antibody internalization assay using pH sensor fluorescent dye.

Science.gov (United States)

Nath, Nidhi; Godat, Becky; Zimprich, Chad; Dwight, Stephen J; Corona, Cesear; McDougall, Mark; Urh, Marjeta

2016-04-01

Receptor-mediated antibody internalization is a key mechanism underlying several anti-cancer antibody therapeutics. Delivering highly toxic drugs to cancer cells, as in the case of antibody drug conjugates (ADCs), efficient removal of surface receptors from cancer cells and changing the pharmacokinetics profile of the antibody drugs are some of key ways that internalization impacts the therapeutic efficacy of the antibodies. Over the years, several techniques have been used to study antibody internalization including radiolabels, fluorescent microscopy, flow cytometry and cellular toxicity assays. While these methods allow analysis of internalization, they have limitations including a multistep process and limited throughput and are generally endpoint assays. Here, we present a new homogeneous method that enables time and concentration dependent measurements of antibody internalization. The method uses a new hydrophilic and bright pH sensor dye (pHAb dye), which is not fluorescent at neutral pH but becomes highly fluorescent at acidic pH. For receptor mediated antibody internalization studies, antibodies against receptors are conjugated with the pHAb dye and incubated with the cells expressing the receptors. Upon binding to the receptor, the dyes conjugated to the antibody are not fluorescent because of the neutral pH of the media, but upon internalization and trafficking into endosomal and lysosomal vesicles the pH drops and dyes become fluorescent. The enabling attributes of the pHAb dyes are the hydrophilic nature to minimize antibody aggregation and bright fluorescence at acidic pH which allows development of simple plate based assays using a fluorescent reader. Using two different therapeutic antibodies--Trastuzumab (anti-HER2) and Cetuximab (anti-EGFR)--we show labeling with pHAb dye using amine and thiol chemistries and impact of chemistry and dye to antibody ration on internalization. We finally present two new approaches using the pHAb dye, which will be

Pathways to the PhD in Nursing: An Analysis of Similarities and Differences.

Science.gov (United States)

Nehls, Nadine; Barber, Gale; Rice, Elizabeth

2016-01-01

New educational pathways are needed to increase the number of doctor of philosophy (PhD)-prepared nurses. To address this need, an early-entry PhD option designed to engage students in PhD coursework and research during the undergraduate nursing major was developed at the University of Wisconsin-Madison. An evaluation comparing the early-entry option with two more conventional entry points was conducted. Three groups (N = 84) comprised the sample: (a) early-entry students admitted as undergraduates or immediately upon graduation (N = 29), (b) mid-entry students with baccalaureate degrees and at least 1 year of work experience (N = 27), and (c) delayed-entry students with master's degrees and 1 or more years of work experience (N = 28). Qualitative and quantitative data were collected from the 3 groups of students who were admitted from 2002 to 2011. The sources of data were transcriptions of individual interviews and reviews of existing data. Seventy-seven percent of the sample participated in the individual interviews. The database review included all students who matriculated into the PhD program. Common themes among the 3 groups included a need for educational funding, the importance of a faculty mentor, and concern about preparation for the teaching role and the academic work environment. The groups were also comparable in terms of research productivity during doctoral study and postgraduation employment. Differences were found on measures of diversity, program progression, and perceptions of clinical competence. The findings provide needed data for the development and expansion of educational pathways to the PhD in nursing. Copyright © 2016 Elsevier Inc. All rights reserved.

Versatile common instrumentation for optical detection of pH and dissolved oxygen

Energy Technology Data Exchange (ETDEWEB)

Sardesai, Neha [Department of Computer Science and Electrical Engineering, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250 (United States); Rao, Govind [Center for Advanced Sensor Technology and Department of Chemical, Biochemical, and Environmental Engineering, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250 (United States); Kostov, Yordan, E-mail: kostov@umbc.edu [Department of Computer Science and Electrical Engineering, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250 (United States); Center for Advanced Sensor Technology and Department of Chemical, Biochemical, and Environmental Engineering, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250 (United States)

2015-07-15

The recent trend toward use of disposable and miniature bioreactors requires the use of appropriate sensors. pH and dissolved oxygen (DO) are often measured using optical chemical sensors due to their small form factor and convenience in use. These sensors are often interrogated using a specialized opto-electronic transducer that is designed around the optical sensor. In this contribution, we are presenting a new class of opto-electronic transducers that are usable with several different chemical sensors without the need to switch the optics or hardware when changing the type of the chemical sensor. This allows flexibility closer to the lab-grade devices while the size is closer to a dedicated sensor. This versatile instrumentation is capable of seamlessly switching between the pH and DO measurement modes and is capable of auto recognition of the sensor type. The principle of ratiometric fluorescence is used for pH measurements, and that of fluorescence lifetime for DO measurements. An approach to obtain identical calibrations between several devices is also presented. The described hardware constitutes common instrumentation for measuring either pH or DO and has been tested in actual bioprocesses. It has been found adequate for continuous bioprocess monitoring.

Versatile common instrumentation for optical detection of pH and dissolved oxygen

International Nuclear Information System (INIS)

Sardesai, Neha; Rao, Govind; Kostov, Yordan

2015-01-01

The recent trend toward use of disposable and miniature bioreactors requires the use of appropriate sensors. pH and dissolved oxygen (DO) are often measured using optical chemical sensors due to their small form factor and convenience in use. These sensors are often interrogated using a specialized opto-electronic transducer that is designed around the optical sensor. In this contribution, we are presenting a new class of opto-electronic transducers that are usable with several different chemical sensors without the need to switch the optics or hardware when changing the type of the chemical sensor. This allows flexibility closer to the lab-grade devices while the size is closer to a dedicated sensor. This versatile instrumentation is capable of seamlessly switching between the pH and DO measurement modes and is capable of auto recognition of the sensor type. The principle of ratiometric fluorescence is used for pH measurements, and that of fluorescence lifetime for DO measurements. An approach to obtain identical calibrations between several devices is also presented. The described hardware constitutes common instrumentation for measuring either pH or DO and has been tested in actual bioprocesses. It has been found adequate for continuous bioprocess monitoring

Cerebral interstitial tissue oxygen tension, pH, HCO3, CO2.

Science.gov (United States)

Charbel, F T; Hoffman, W E; Misra, M; Hannigan, K; Ausman, J I

1997-10-01

There are many techniques for monitoring the injured brain following trauma, subarachnoid hemorrhage, or surgery. It is thought that the major determinants for recovery of injured cerebral tissue are oxygen, glucose delivery, and the clearance of metabolites. These factors, at optimal levels, are probably responsible for the regaining of neuronal functions. These parameters are in turn dependent on the tissue's blood flow and metabolism. We have been using a single, compact, polyethylene sensor, the Paratrend 7 for the measurement of cerebral oxygen tension, CO2, pH, and temperature. This sensor is designed for continuous blood gas analysis to aid in monitoring neurosurgical patients, both during surgery and in the intensive care unit. Using the Paratrend 7 sensor, we found the normal range of values to be: PO2 33 +/- 11 mm Hg; PCO2 48 +/- 7 mm Hg; pH 7.19 +/- 0.11. Critical measurements are considered to be tissue PO2 60 mm Hg, and pH effective method of measuring tissue cerebral oxygen tension, along with carbon dioxide levels, pH, and temperature.

High pH ammonia toxicity, and the search for life on the Jovian planets.

Science.gov (United States)

Deal, P H; Souza, K A; Mack, H M

1975-10-01

Jovian plants have enviroments apparently suitable for the evolution of life, but nevertheless, present severe challenges to organisms. One such challenge arises from the presence of ammonia. Ammonia is an efficient biocide, its effect being dependent on pH as well as on concentration. The effects of pH and ammonia concentration were studied separately, where possible, on a variety of organisms, including some isolated from natural enviornments of high pH and/or ammonia concentration. Escherichia coli and Bacillus subtilis are both extremely sensitive to ammonia. An aerobic organism (growth up to pH 11.4) from an alkaline spring is more resistant, but exhibits a toxic response to ammonia at a pH much lower than its maximum for growth. The greatest ammonia resistance has been found in an unidentified organism growing at near neutral pH. Even in this case, however, survival at ammonia concentrations reasonably expected on the Jovian planets is measured in hours. This is, nevertheless, two to three orders of magnitude longer than for E. coli. Our data support the tentative conclusion that contamination of the Jovian planets with terrestrial organisms that can grow is unlikely. However, the range of toxic response noted, coupled with the observation that terrestrial life has not been exposed to high ammonia concentrations for millions of years, suggests that adaptation to greater ammonia tolerance may be possible.

Nanoparticle/Polymer assembled microcapsules with pH sensing property.

Science.gov (United States)

Zhang, Pan; Song, Xiaoxue; Tong, Weijun; Gao, Changyou

2014-10-01

The dual-labeled microcapsules via nanoparticle/polymer assembly based on polyamine-salt aggregates can be fabricated for the ratiometric intracellular pH sensing. After deposition of SiO2 nanoparticles on the poly(allylamine hydrochloride)/multivalent anionic salt aggregates followed by silicic acid treatment, the generated microcapsules are stable in a wide pH range (3.0 ∼ 8.0). pH sensitive dye and pH insensitive dye are simultaneously labeled on the capsules, which enable the ratiometric pH sensing. Due to the rough and positively charged surface, the microcapsules can be internalized by several kinds of cells naturally. Real-time measurement of intracellular pH in several living cells shows that the capsules are all located in acidic organelles after being taken up. Furthermore, the negatively charged DNA and dyes can be easily encapsulated into the capsules via charge interaction. The microcapsules with combination of localized pH sensing and drug loading abilities have many advantages, such as following the real-time transportation and processing of the carriers in cells. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

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

pH tolerance of Daphnia pulex (leydig, emend. , richard)

Energy Technology Data Exchange (ETDEWEB)

Davis, P; Ozburn, G W

1969-01-01

The survival time and reproduction of female Daphnia pulex in solutions varying in pH have been observed. Dilute sodium hydroxide or sulfuric acid solutions were added to four different diluent waters: distilled water, aerated tap water, aerated and filtered tap water from an aquarium containing Dace minnows, and Mcintyre River water. D. Pulex (initially up to 72 hours old) survived for the duration of the experiment (32 hours) in river water within a pH range of 6.1 to 10.3; in aquarium water within a pH range of 4.3 to 10.4; only at pH 6.4 and pH 7.6 in distilled water; and in none of the solutions using aerated tap water. The dissolved oxygen content was measured at the beginning and end of every experiment and was found never to fall below 6.2 p.p.M. Those individuals which survived were cultured in the laboratory and parthenogenesis was observed at pH values between 7.0 and 8.7.

Methods of pH determination in Calcareous soils of Oman: The effect of Electrolyte and soil solution ratio

International Nuclear Information System (INIS)

Al-Busaidi, A.; Cookson, P.

2002-01-01

Determination of pH assists in understanding many reactions that occur in soil. Soil pH values are highly sensitive to the procedure used for determination. In this study, pH was measured in different electrolytes [distilled water (pHw), 0.01MCaCl2 (pHCa), 1MKCl (pHk), and 0.01MBaCl2 (pHba)] with different soil: electrolyte ratios (i.e. 1:1, 1:2.5 and 1:5). The objective was to determine the effect of each electrolyte and dilution ratio on pH of saline and non-saline soils from Oman. It was found that ph values varied significantly between electrolytes and with different dilution ratios. Linear regression equations were generated between electrolytes, dilution ratios and were mostly significant. Soil pH values determined in different electrolytes were significantly interrelated. Water appeared as a highly suitable solvent for soil pH measurements because it is simple and values familiar to soil users. However, alkaline errors and electrode instabilities due to liquid junction and soluble salt effects, affected soil pH measurements, especially in water, and resulted in alkaline errors during pH measurements. Errors were minimized when pH was measured in electrolytes rather than in water. (author)

δ11B as monitor of calcification site pH in divergent marine calcifying organisms

Science.gov (United States)

Sutton, Jill N.; Liu, Yi-Wei; Ries, Justin B.; Guillermic, Maxence; Ponzevera, Emmanuel; Eagle, Robert A.

2018-03-01

The boron isotope composition (δ11B) of marine biogenic carbonates has been predominantly studied as a proxy for monitoring past changes in seawater pH and carbonate chemistry. However, a number of assumptions regarding chemical kinetics and thermodynamic isotope exchange reactions are required to derive seawater pH from δ11B biogenic carbonates. It is also probable that δ11B of biogenic carbonate reflects seawater pH at the organism's site of calcification, which may or may not reflect seawater pH. Here, we report the development of methodology for measuring the δ11B of biogenic carbonate samples at the multi-collector inductively coupled mass spectrometry facility at Ifremer (Plouzané, France) and the evaluation of δ11BCaCO3 in a diverse range of marine calcifying organisms reared for 60 days in isothermal seawater (25 °C) equilibrated with an atmospheric pCO2 of ca. 409 µatm. Average δ11BCaCO3 composition for all species evaluated in this study range from 16.27 to 35.09 ‰, including, in decreasing order, coralline red alga Neogoniolithion sp. (35.89 ± 3.71 ‰), temperate coral Oculina arbuscula (24.12 ± 0.19 ‰), serpulid worm Hydroides crucigera (19.26 ± 0.16 ‰), tropical urchin Eucidaris tribuloides (18.71 ± 0.26 ‰), temperate urchin Arbacia punctulata (16.28 ± 0.86 ‰), and temperate oyster Crassostrea virginica (16.03 ‰). These results are discussed in the context of each species' proposed mechanism of biocalcification and other factors that could influence skeletal and shell δ11B, including calcifying site pH, the proposed direct incorporation of isotopically enriched boric acid (instead of borate) into biogenic calcium carbonate, and differences in shell/skeleton polymorph mineralogy. We conclude that the large inter-species variability in δ11BCaCO3 (ca. 20 ‰) and significant discrepancies between measured δ11BCaCO3 and δ11BCaCO3 expected from established relationships between abiogenic δ11BCaCO3 and seawater pH arise

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

Chemical Composition and Evaluation of Nicotine, Tobacco Alkaloids, pH, and Selected Flavors in E-Cigarette Cartridges and Refill Solutions.

Science.gov (United States)

Lisko, Joseph G; Tran, Hang; Stanfill, Stephen B; Blount, Benjamin C; Watson, Clifford H

2015-10-01

Electronic cigarette (e-cigarette) use is increasing dramatically in developed countries, but little is known about these rapidly evolving products. This study analyzed and evaluated the chemical composition including nicotine, tobacco alkaloids, pH, and flavors in 36 e-liquids brands from 4 manufacturers. We determined the concentrations of nicotine, alkaloids, and select flavors and measured pH in solutions used in e-cigarettes. E-cigarette products were chosen based upon favorable consumer approval ratings from online review websites. Quantitative analyses were performed using strict quality assurance/quality control validated methods previously established by our lab for the measurement of nicotine, alkaloids, pH, and flavors. Three-quarters of the products contained lower measured nicotine levels than the stated label values (6%-42% by concentration). The pH for e-liquids ranged from 5.1-9.1. Minor tobacco alkaloids were found in all samples containing nicotine, and their relative concentrations varied widely among manufacturers. A number of common flavor compounds were analyzed in all e-liquids. Free nicotine levels calculated from the measurement of pH correlated with total nicotine content. The direct correlation between the total nicotine concentration and pH suggests that the alkalinity of nicotine drives the pH of e-cigarette solutions. A higher percentage of nicotine exists in the more absorbable free form as total nicotine concentration increases. A number of products contained tobacco alkaloids at concentrations that exceed U.S. pharmacopeia limits for impurities in nicotine used in pharmaceutical and food products. © Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Qualitative methods in PhD theses from general practice in Scandinavia.

Science.gov (United States)

Malterud, Kirsti; Hamberg, Katarina; Reventlow, Susanne

2017-12-01

Qualitative methodology is gaining increasing attention and esteem in medical research, with general practice research taking a lead. With these methods, human and social interaction and meaning can be explored and shared by systematic interpretation of text from talk, observation or video. Qualitative studies are often included in Ph.D. theses from general practice in Scandinavia. Still, the Ph.D. programs across nations and institutions offer only limited training in qualitative methods. In this opinion article, we draw upon our observations and experiences, unpacking and reflecting upon values and challenges at stake when qualitative studies are included in Ph.D. theses. Hypotheses to explain these observations are presented, followed by suggestions for standards of evaluation and improvement of Ph.D. programs. The authors conclude that multimethod Ph.D. theses should be encouraged in general practice research, in order to offer future researchers an appropriate toolbox.

Some observations of the pH of precipitation elements

Energy Technology Data Exchange (ETDEWEB)

Landsberg, H

1954-01-01

A year of observations of pH values of individual rain drops and snowflakes near Boston, Mass., showed acidic values ranging from 3 to 5.5 with a mean value of 4. There was no systematic relation between pH and the duration of rainfall. Drizzle and light rain had the lowest values, heavy rain and solid precipitation had the highest. There is a tendency for smaller drops to have lower values of pH than the larger ones. Measurements of dew and frost showed also a range from 3 to 5.5 with a mean value of 4.3.

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

PH in Rockwool Propagation Blocks: a Method to Measure the pH Buffer Capacity of Rockwool and Other Mineral Wool Media

NARCIS (Netherlands)

Blok, C.; Kaarsemaker, R.C.

2013-01-01

Within the framework of the international KIWA quality label for rooting media representatives of plant propagators and the rockwool industry agreed to develop a method to characterize the influence of the rooting medium materials on the pH in cultivation. A method for the characterization of

Design and application of optical nanosensors for pH imaging in cell compartments

DEFF Research Database (Denmark)

Benjaminsen, Rikke Vicki; Almdal, Kristoffer

the last two decades. However, even though these sensor systems have proven themselves as superior to conventional methods, there are still questions about the use of these sensors that need to be addressed, especially regarding sensor design and calibration. We have developed a new triple-labelled p......Measurements of pH in acidic cellular compartments of mammalian cells is important for our understanding of cell metabolism, and organelle acidification is an essential event in living cells especially in the endosomal-lysosomal pathway where pH is critical for cellular sorting of internalized...... material. Intracellular pH can be measured by the use of fluorescence ratio imaging microscopy (FRIM), however, available methods for pH measurements in living cells are not optimal. Nanoparticle based optical sensor technology for quantification of metabolites in living cells has been developed over...

Development and characterization of a voltammetric carbon-fiber microelectrode pH sensor.

Science.gov (United States)

Makos, Monique A; Omiatek, Donna M; Ewing, Andrew G; Heien, Michael L

2010-06-15

This work describes the development and characterization of a modified carbon-fiber microelectrode sensor capable of measuring real-time physiological pH changes in biological microenvironments. The reagentless sensor was fabricated under ambient conditions from voltammetric reduction of the diazonium salt Fast Blue RR onto a carbon-fiber surface in aprotic media. Fast-scan cyclic voltammetry was used to probe redox activity of the p-quinone moiety of the surface-bound molecule as a function of pH. In vitro calibration of the sensor in solutions ranging from pH 6.5 to 8.0 resulted in a pH-dependent anodic peak potential response. Flow-injection analysis was used to characterize the modified microelectrode, revealing sensitivity to acidic and basic changes discernible to 0.005 pH units. Furthermore, the modified electrode was used to measure dynamic in vivo pH changes evoked during neurotransmitter release in the central nervous system of the microanalytical model organism Drosophila melanogaster.

Development of a downhole tool measuring real-time concentration of ionic tracers and pH in geothermal reservoirs

Science.gov (United States)

Hess, Ryan F.; Boyle, Timothy J.; Limmer, Steven; Yelton, William G.; Bingham, Samuel; Stillman, Greg; Lindblom, Scott; Cieslewski, Grzegorz

2014-06-01

For enhanced or Engineered Geothermal Systems (EGS) geothermal brine is pumped to the surface via the production wells, the heat extracted to turn a turbine to generate electricity, and the spent brine re-injected via injection wells back underground. If designed properly, the subsurface rock formations will lead this water back to the extraction well as heated brine. Proper monitoring of these geothermal reservoirs is essential for developing and maintaining the necessary level of productivity of the field. Chemical tracers are commonly used to characterize the fracture network and determine the connectivity between the injection and production wells. Currently, most tracer experiments involve injecting the tracer at the injection well, manually collecting liquid samples at the wellhead of the production well, and sending the samples off for laboratory analysis. While this method provides accurate tracer concentration data at very low levels of detection, it does not provide information regarding the location of the fractures which were conducting the tracer between wellbores. Sandia is developing a high-temperature electrochemical sensor capable of measuring tracer concentrations and pH downhole on a wireline tool. The goal of this effort is to collect real-time pH and ionic tracer concentration data at temperatures up to 225 °C and pressures up to 3000 psi. In this paper, a prototype electrochemical sensor and the initial data obtained will be presented detailing the measurement of iodide tracer concentrations at high temperature and pressure in a newly developed laboratory scale autoclave.

A ratiometric approach for pH optosensing with a single fluorophore indicator

Energy Technology Data Exchange (ETDEWEB)

Sanchez-Barragan, I. [Department of Physical and Analytical Chemistry, University of Oviedo, c/ Julian Claveria 8, 33006 Oviedo (Spain); Costa-Fernandez, J.M. [Department of Physical and Analytical Chemistry, University of Oviedo, c/ Julian Claveria 8, 33006 Oviedo (Spain); Sanz-Medel, A. [Department of Physical and Analytical Chemistry, University of Oviedo, c/ Julian Claveria 8, 33006 Oviedo (Spain); Valledor, Marta [Department of Electric, Electronic, Computers and Systems Engineering, University of Oviedo, Edificio Departamental no. 3, Campus de Viesques, 33204 Gijon (Spain); Ferrero, Francisco J. [Department of Electric, Electronic, Computers and Systems Engineering, University of Oviedo, Edificio Departamental no. 3, Campus de Viesques, 33204 Gijon (Spain)]. E-mail: ferrero@ate.uniovi.es; Campo, Juan Carlos [Department of Electric, Electronic, Computers and Systems Engineering, University of Oviedo, Edificio Departamental no. 3, Campus de Viesques, 33204 Gijon (Spain)

2006-03-15

A new fiber-optic prototype of luminometer has been designed in order to perform ratiometric-based measurements for optical sensing purposes. The coupling of a pH-selective sensing phase to the fiber-optic prototype has been evaluated for robust pH optosensing in drinking water. The pH-sensitive material has been synthesized by entrapping a pH-sensitive luminescent indicator (mercurochrome) in a sol-gel inorganic matrix. The pH optosensing is based on the detection of pH-induced reversible changes in the mercurochrome fluorescent emission and in the light reflected by the sensing phase. The instrument has been constructed using low-cost and simple optoelectronic components. The active phase was excited by means of a visible 470 nm high intensity light emitting diode (LED). The radiant power of the LED was modulated using a sinusoidal function so that scattered light due to light sources of different frequency than the modulating signal (e.g. sunlight) can be easily removed by adequate electronic filtering of the emission signal. Both the fluorescence emission from the dye and the sensing phase reflected light were collected in a bifurcated fiber-optic to allow the ratiometric measurement. Two different ratiometric approaches have been evaluated. The analytical performance of the pH optrode using both measurement methods have been compared, between them and with simple fluorescence intensity measurements, in terms of sensitivity, measurement range, response time, repeatability and insensitivity to changes in excitation light intensity. The applicability of the developed pH optrode and methods has been tested for pH analysis in tap and bottled still mineral water samples. The results obtained showed good agreement with the corresponding pH values provided by a commercial glass electrode. In this work, pH was selected as a model analyte to evaluate the performance of the proposed methodology, although other optical sensors for different applications/analytes could

A ratiometric approach for pH optosensing with a single fluorophore indicator

International Nuclear Information System (INIS)

Sanchez-Barragan, I.; Costa-Fernandez, J.M.; Sanz-Medel, A.; Valledor, Marta; Ferrero, Francisco J.; Campo, Juan Carlos

2006-01-01

A new fiber-optic prototype of luminometer has been designed in order to perform ratiometric-based measurements for optical sensing purposes. The coupling of a pH-selective sensing phase to the fiber-optic prototype has been evaluated for robust pH optosensing in drinking water. The pH-sensitive material has been synthesized by entrapping a pH-sensitive luminescent indicator (mercurochrome) in a sol-gel inorganic matrix. The pH optosensing is based on the detection of pH-induced reversible changes in the mercurochrome fluorescent emission and in the light reflected by the sensing phase. The instrument has been constructed using low-cost and simple optoelectronic components. The active phase was excited by means of a visible 470 nm high intensity light emitting diode (LED). The radiant power of the LED was modulated using a sinusoidal function so that scattered light due to light sources of different frequency than the modulating signal (e.g. sunlight) can be easily removed by adequate electronic filtering of the emission signal. Both the fluorescence emission from the dye and the sensing phase reflected light were collected in a bifurcated fiber-optic to allow the ratiometric measurement. Two different ratiometric approaches have been evaluated. The analytical performance of the pH optrode using both measurement methods have been compared, between them and with simple fluorescence intensity measurements, in terms of sensitivity, measurement range, response time, repeatability and insensitivity to changes in excitation light intensity. The applicability of the developed pH optrode and methods has been tested for pH analysis in tap and bottled still mineral water samples. The results obtained showed good agreement with the corresponding pH values provided by a commercial glass electrode. In this work, pH was selected as a model analyte to evaluate the performance of the proposed methodology, although other optical sensors for different applications/analytes could

Zonal NePhRO scoring system: a superior renal tumor complexity classification model.

Science.gov (United States)

Hakky, Tariq S; Baumgarten, Adam S; Allen, Bryan; Lin, Hui-Yi; Ercole, Cesar E; Sexton, Wade J; Spiess, Philippe E

2014-02-01

Since the advent of the first standardized renal tumor complexity system, many subsequent scoring systems have been introduced, many of which are complicated and can make it difficult to accurately measure data end points. In light of these limitations, we introduce the new zonal NePhRO scoring system. The zonal NePhRO score is based on 4 anatomical components that are assigned a score of 1, 2, or 3, and their sum is used to classify renal tumors. The zonal NePhRO scoring system is made up of the (Ne)arness to collecting system, (Ph)ysical location of the tumor in the kidney, (R)adius of the tumor, and (O)rganization of the tumor. In this retrospective study, we evaluated patients exhibiting clinical stage T1a or T1b who underwent open partial nephrectomy performed by 2 genitourinary surgeons. Each renal unit was assigned both a zonal NePhRO score and a RENAL (radius, exophytic/endophytic properties, nearness of tumor to the collecting system or sinus in millimeters, anterior/posterior, location relative to polar lines) score, and a blinded reviewer used the same preoperative imaging study to obtain both scores. Additional data points gathered included age, clamp time, complication rate, urine leak rate, intraoperative blood loss, and pathologic tumor size. One hundred sixty-six patients underwent open partial nephrectomy. There were 37 perioperative complications quantitated using the validated Clavien-Dindo system; their occurrence was predicted by the NePhRO score on both univariate and multivariate analyses (P = .0008). Clinical stage, intraoperative blood loss, and tumor diameter were all correlated with the zonal NePhRO score on univariate analysis only. The zonal NePhRO scoring system is a simpler tool that accurately predicts the surgical complexity of a renal lesion. Copyright © 2014 Elsevier Inc. All rights reserved.

Post-deposition annealing temperature dependence TiO_2-based EGFET pH sensor sensitivity

International Nuclear Information System (INIS)

Zulkefle, M. A.; Rahman, R. A.; Yusoff, K. A.; Abdullah, W. F. H.; Rusop, M.; Herman, S. H.

2016-01-01

EGFET pH sensor is one type of pH sensor that is used to measure and determine pH of a solution. The sensing membrane of EGFET pH sensor plays vital role in the overall performance of the sensor. This paper studies the effects of different annealing temperature of the TiO_2 sensing membranes towards sensitivity of EGFET pH sensor. Sol-gel spin coating was chosen as TiO_2 deposition techniques since it is cost-effective and produces thin film with uniform thickness. Deposited TiO_2 thin films were then annealed at different annealing temperatures and then were connected to the gate of MOSFET as a part of the EGFET pH sensor structure. The thin films now act as sensing membranes of the EGFET pH sensor and sensitivity of each sensing membrane towards pH was measured. From the results it was determined that sensing membrane annealed at 300 °C gave the highest sensitivity followed by sample annealed at 400 °C and 500 °C.

Measuring efficiency of university-industry Ph.D. projects using best worst method

NARCIS (Netherlands)

Salimi, N.; Rezaei, J.

2016-01-01

A collaborative Ph.D. project, carried out by a doctoral candidate, is a type of collaboration between university and industry. Due to the importance of such projects, researchers have considered different ways to evaluate the success, with a focus on the outputs of these projects. However, what

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...

Assessment of uncertainties in measurement of pH in hostile environments characteristic of nuclear repositories

International Nuclear Information System (INIS)

Kreider, K.G.; Tarlov, M.J.; Huang, P.H.

1991-10-01

This report focuses on evaluation and characteristics of sputtered thin film pH electrodes which can be used to assess the corrosivity of hot (100 degree C) aqueous solutions present in nuclear repositories. Sputtered thin films have the advantages of high temperature capability, ruggedness, and low cost. The iridium oxide films were found to have a linear, 58 mV/pH, response to changes in pH. They had little hysteresis but drifted approximately 0.2 V over a period of two days exposure to pH 2--12 solutions. The films were found to be insensitive to interference from most ions such as alkali ions but had redox sensitivity to ferri-/ferrocyanide ions. Although special surface treatments were needed for the films for good adherence at 200 degree C the films were not degraded after 20 hours exposure at pH 4, 7, and 10 at 200 degree C. Ruthenium oxide sputtered films performed equally well to the iridium oxide films in parallel tests. The report also contains information on electrochemistry and testing of thin film electrodes and the characterization of the thin films by x-ray photoemission spectroscopy, ultraviolet photoemission spectroscopy, and ion scattering spectroscopy. 123 refs., 29 figs., 7 tabs

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.

Establishment of a gaseous pH control concept in microbioreactors

DEFF Research Database (Denmark)

Zainal Alam, Muhd Nazrul Hisham Bin; Schäpper, Daniel; Gernaey, Krist

2012-01-01

Existing methods for pH control in bench-scale bioreactor systems often cannot be directly adapted for microbioreactors. This is because microbioreactors are commonly designed to work with constant volumes, operate bubble-free and have no headspace, which technically rules out any possibility...... of adding acid/base solution for pH control in microbioreactors. This work reports on the establishment of a gaseous pH control concept in microbioreactors where pH control was achieved by dosing of ammonia (NH3, 20 000 ppm) and pure carbon dioxide (CO2) gases to respectively; increase and lower the pH...... of the reactor content. It encompasses the establishment of an optical pH measurement by means of a fluorescent sensor spot, realization of the necessary gas connections, mixing of gases, and gas-exchange via a thin semi-permeable poly(dimethylsiloxane) (PDMS) membrane. It was shown that addition of NH3 and CO2...

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.

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.

Application of zirconia membranes as high-temperature PH sensors

International Nuclear Information System (INIS)

Neidrach, L.W.

1983-01-01

The zirconia pH sensor behaves much like the classical glass electrode, but it extends the range of measurement to much higher temperatures - about 300 0 vs 120 0 C. It also has virtues over the glass electrode at lower temperatures because of the absence of an ''alkaline error.'' Like the glass electrode, it is insensitive to changes in the redox potential of the environment and, in turn, it exerts no influence on the environment. Such sensors have been finding application in the direct measurement of the pH of geothermal brines, of water in nuclear reactors, and in high-temperature corrosion studies. The sensors can also be used as ''pseudoreference'' electrodes for the measurement of redox and corrosion potentials in high-temperature media

Plasmodium falciparum chloroquine resistance transporter (PfCRT) isoforms PH1 and PH2 perturb vacuolar physiology.

Science.gov (United States)

Callaghan, Paul S; Siriwardana, Amila; Hassett, Matthew R; Roepe, Paul D

2016-03-31

Recent work has perfected yeast-based methods for measuring drug transport by the Plasmodium falciparum chloroquine (CQ) resistance transporter (PfCRT). The approach relies on inducible heterologous expression of PfCRT in Saccharomyces cerevisiae yeast. In these experiments selecting drug concentrations are not toxic to the yeast, nor is expression of PfCRT alone toxic. Only when PfCRT is expressed in the presence of CQ is the growth of yeast impaired, due to inward transport of chloroquine (CQ) via the transporter. During analysis of all 53 known naturally occurring PfCRT isoforms, two isoforms (PH1 and PH2 PfCRT) were found to be intrinsically toxic to yeast, even in the absence of CQ. Additional analysis of six very recently identified PfCRT isoforms from Malaysia also showed some toxicity. In this paper the nature of this yeast toxicity is examined. Data also show that PH1 and PH2 isoforms of PfCRT transport CQ with an efficiency intermediate to that catalyzed by previously studied CQR conferring isoforms. Mutation of PfCRT at position 160 is found to perturb vacuolar physiology, suggesting a fitness cost to position 160 amino acid substitutions. These data further define the wide range of activities that exist for PfCRT isoforms found in P. falciparum isolates from around the globe.

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.

Pressure pressure-balanced pH sensing system for high temperature and high pressure water

International Nuclear Information System (INIS)

Tachibana, Koji

1995-01-01

As for the pH measurement system for high temperature, high pressure water, there have been the circumstances that first the reference electrodes for monitoring corrosion potential were developed, and subsequently, it was developed for the purpose of maintaining the soundness of metallic materials in high temperature, high pressure water in nuclear power generation. In the process of developing the reference electrodes for high temperature water, it was clarified that the occurrence of stress corrosion cracking in BWRs is closely related to the corrosion potential determined by dissolved oxygen concentration. As the types of pH electrodes, there are metal-hydrogen electrodes, glass electrodes, ZrO 2 diaphragm electrodes and TiO 2 semiconductor electrodes. The principle of pH measurement using ZrO 2 diaphragms is explained. The pH measuring system is composed of YSZ element, pressure-balanced type external reference electrode, pressure balancer and compressed air vessel. The stability and pH response of YSZ elements are reported. (K.I.)

Ionized calcium analyzer with a built-in pH correction.

Science.gov (United States)

Fogh-Andersen, N

1981-07-01

We describe a new semi-automated apparatus for simultaneously measuring the concentration of free calcium ion and of hydrogen ion (pH) at 37 degrees C. The sample volume is 110 microL. In addition to the actual values for these concentrations in the sample, the apparatus calculates the concentration of free calcium ion at pH 7.40. Mean values for serum from 51 fasting bedridden patients without calcium metabolic disorders and 64 fasting hospital employees were 1.192 and 1.232 mmol/L, respectively, with SD of 0.042 and 0.040 mmol/L, respectively. The within-series analytical SD was 12 mumol/L and the day-to-day SD of the pH-corrected concentration of free calcium ion was 21 mumol/L, as calculated from measurements made on a serum pool after equilibration with a CO2--air mixture. The mean dependency on pH as determined in 120 consecutive patients' sera equalled the built-in pH correction. The accuracy was evaluated by comparison with other calcium ion-selective electrodes.

In Vivo EPR Assessment of pH, pO2, Redox Status, and Concentrations of Phosphate and Glutathione in the Tumor Microenvironment.

Science.gov (United States)

Bobko, Andrey A; Eubank, Timothy D; Driesschaert, Benoit; Khramtsov, Valery V

2018-03-16

This protocol demonstrates the capability of low-field electron paramagnetic resonance (EPR)-based techniques in combination with functional paramagnetic probes to provide quantitative information on the chemical tumor microenvironment (TME), including pO2, pH, redox status, concentrations of interstitial inorganic phosphate (Pi), and intracellular glutathione (GSH). In particular, an application of a recently developed soluble multifunctional trityl probe provides unsurpassed opportunity for in vivo concurrent measurements of pH, pO2 and Pi in Extracellular space (HOPE probe). The measurements of three parameters using a single probe allow for their correlation analyses independent of probe distribution and time of the measurements.

Partnership for development: A peer mentorship model for PhD students.

Science.gov (United States)

Lewinski, Allison A; Mann, Tara; Flores, Dalmacio; Vance, Ashlee; Bettger, Janet Prvu; Hirschey, Rachel

Formal mentoring relationships socialize Doctor of Philosophy (PhD) students to their current and future roles as nursing scholars. Despite formal mentoring, some students may desire or benefit from additional mentoring in an informal setting. Informal mentoring complements the one-to-one relationship students develop with a primary faculty mentor or dissertation chair. This manuscript describes the development, implementation, and evaluation of a student-driven, peer mentorship model, titled Partnership for Development. This small group, peer mentorship model was implemented in a PhD program at a School of Nursing during an academic year. Five student peer facilitators organized a total of 32 PhD students, 2 post-doctoral associates, and invited 5 faculty to participate. Data includes pre- and post-implementation surveys completed by the students and peer facilitator field notes. Student reported post-participation benefits included: getting to know faculty in an informal setting (n=6), socializing with students from other cohorts (n=6), and obtaining a sense of camaraderie with other PhD students (n=5). We recommend peer mentorship for other PhD programs as a way to socialize PhD students into the role of nurse scientist and assist students during their tenure as a PhD student. Copyright © 2017 Elsevier Inc. All rights reserved.

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.

Measurement of pH, alkalinity and acidity in ultra-soft waters | Lahav ...

African Journals Online (AJOL)

In the "blend" method, equilibrium chemistry data were used to calculate total acidity for each point based on the known total alkalinity, pH reading, temperature and ionic strength. The two methods gave excellent results (in terms of both repetition and accuracy) as compared to characterisation based on total alkalinity and ...

Gastrointestinal pH profile in subjects with irritable bowel syndrome.

Science.gov (United States)

Lalezari, David

2012-01-01

To investigate the small bowel pH profile and small intestine transit time (SITT) in healthy controls and patients with irritable bowel syndrome (IBS). Nine IBS patients (3 males, mean age 35 yr) and 10 healthy subjects (6 males, mean age 33 yr) were studied. Intestinal pH profile and SITT were assessed by a wireless motility pH and pressure capsule (Smart Pill). Mean pH values were measured in the small intestine (SI) and compared both within and between groups. Data presented as mean or median, ANOVA, P <0.05 for significance. We found the pH for the first (Q1), second (Q2), third (Q3), and fourth quartile (Q4) of the SI in healthy versus IBS patients was 5.608 ± 0.491 vs. 5.667 ± 0.297, 6.200 ± 0.328 vs. 6.168 ± 0.288, 6.679 ± 0.316 vs. 6.741 ± 0.322, and 6.884 ± 0.200 vs. 6.899 ± 0.303, respectively. We found no significant group difference in pH per quartile (P=0.7979). The proximal SI was significantly more acidic, compared to distal segments, in both healthy subjects and IBS patients (P<0.0001). We found no significant difference in the measured SITT between IBS and control groups with a mean SITT of 218.56 ± 59.60 min and 199.20 ± 82.31 min, respectively (P=0.55). This study shows the presence of a gradient of pH along the SI, in both IBS and healthy subjects, the distal being less acidic. These finding may be of importance in small bowel homeostasis.

Application of hydrogel-coated microcantilevers as sensing elements for pH

International Nuclear Information System (INIS)

Gonska, Julian; Schelling, Christoph; Urban, Gerald

2009-01-01

This note reports on cantilever-based sensor elements coated with a hydrogel. The hydrogel responds with a volume change on varying the pH value of surrounding liquids. The change in volume leads to a static deflection of the cantilevers, which is detected using integrated piezoresistors. To increase deflection sensitivity of the sensor elements, sub-micron, multilayered cantilevers consisting of polycrystalline silicon and silicon oxide are used. A new cantilever design is developed, which decreases the cantilever sensitivity to in situ stresses and thermal bimorph effects. A theoretical model for the sensor elements is introduced providing the output signal of multiple cantilevers connected in a full Wheatstone bridge. Measurements of deflection sensitivity prove the theoretical model. Finally, the cantilevers are coated with a 2-hydroxyethyl methacrylate and 2-(dimethylamino) ethyl methacrylate copolymer-based hydrogel, and changes in the pH value from pH 4 to pH 10 are measured. (technical note)

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.

PH5: HDF5 Based Format for Integrating and Archiving Seismic Data

Science.gov (United States)

Hess, D.; Azevedo, S.; Falco, N.; Beaudoin, B. C.

2017-12-01

PH5 is a seismic data format created by IRIS PASSCAL using HDF5. Building PH5 on HDF5 allows for portability and extensibility on a scale that is unavailable in older seismic data formats. PH5 is designed to evolve to accept new data types as they become available in the future and to operate on a variety of platforms (i.e. Mac, Linux, Windows). Exemplifying PH5's flexibility is the evolution from just handling active source seismic data to now including passive source, onshore-offshore, OBS and mixed source seismic data sets. In PH5, metadata is separated from the time series data and stored in a size and performance efficient manner that also allows for easy user interaction and output of the metadata in a format appropriate for the data set. PH5's full-fledged "Kitchen Software Suite" comprises tools for data ingestion (e.g. RefTek, SEG-Y, SEG-D, SEG-2, MSEED), meta-data management, QC, waveform viewing, and data output. This software suite not only includes command line and GUI tools for interacting with PH5, it is also a comprehensive Python package to support the creation of software tools by the community to further enhance PH5. The PH5 software suite is currently being used in multiple capacities, including in-field for creating archive ready data sets as well as by the IRIS Data Management Center (DMC) to offer an FDSN compliant set of web services for serving PH5 data to the community in a variety of standard data and meta-data formats (i.e. StationXML, QuakeML, EventXML, SAC + Poles and Zeroes, MiniSEED, and SEG-Y) as well as StationTXT and ShotText formats. These web services can be accessed via standard FDSN clients such as ObsPy, irisFetch.m, FetchData, and FetchMetadata. This presentation will highlight and demonstrate the benefits of PH5 as a next generation adaptable and extensible data format for use in both archiving and working with seismic data.

The acid test of fluoride: how pH modulates toxicity.

Science.gov (United States)

Sharma, Ramaswamy; Tsuchiya, Masahiro; Skobe, Ziedonis; Tannous, Bakhos A; Bartlett, John D

2010-05-28

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 (pHdental fluorosis.

Neutralizing salivary pH by mouthwashes after an acidic challenge.

Science.gov (United States)

Dehghan, Mojdeh; Tantbirojn, Daranee; Kymer-Davis, Emily; Stewart, Colette W; Zhang, Yanhui H; Versluis, Antheunis; Garcia-Godoy, Franklin

2017-05-01

The aim of the present study was to test the neutralizing effect of mouthwashes on salivary pH after an acidic challenge. Twelve participants were recruited for three visits, one morning per week. Resting saliva was collected at baseline and after 2-min swishing with 20 mL orange juice as an acidic challenge. Participants then rinsed their mouth for 30 s with 20 mL water (control), an over-the-counter mouthwash (Listerine), or a two-step mouthwash, randomly assigned for each visit. Saliva was collected immediately, 15, and 45 min after rinsing. The pH values of the collected saliva were measured and analyzed with anova, followed by Student-Newman-Keuls post-hoc test (significance level: 0.05). Orange juice significantly lowered salivary pH. Immediately after rinsing, Listerine and water brought pH back to baseline values, with the pH significantly higher in the Listerine group. The two-step mouthwash raised pH significantly higher than Listerine and water, and higher than the baseline value. Salivary pH returned to baseline and was not significantly different among groups at 15 and 45 min post-rinsing. Mouth rinsing after an acidic challenge increased salivary pH. The tested mouthwashes raised pH higher than water. Mouthwashes with a neutralizing effect can potentially reduce tooth erosion from acid exposure. © 2015 Wiley Publishing Asia Pty Ltd.

pH dependent green synthesis of gold nanoparticles by completely C6-carboxylated curdlan under high temperature and various pH conditions.

Science.gov (United States)

Qiu, Wen-Yi; Wang, Kai; Wang, Yao-Yao; Ding, Zhi-Chao; Wu, Li-Xia; Cai, Wu-Dan; Yan, Jing-Kun

2018-01-01

A C6-carboxylated curdlan (C6-Cc) obtained from 4-acetamido-TEMPO-mediated oxidation of curdlan was used both as a reducing and stabilizing agent for green synthesis of pH-responsive AuNPs, which was carried out by controlling the pH of the C6-Cc solution at a high temperature (100°C). C6-Cc presented a semi-flexible random coil chain in the aqueous medium at pH 5.5 and became more expanded and rigid in alkaline conditions (pH 7.1-12.0), though the primary chemical structure of C6-Cc was virtually unchanged with the pH variation. The AuNPs prepared with C6-Cc at various pHs were characterized by various instrumental measurements. The shapes and sizes of AuNPs were found to be strongly dependent on the pH of the C6-Cc solution. The C6-Cc-decorated AuNPs exhibited a more well-dispersed spherical morphology with smaller particle sizes under alkaline conditions (pH 7.1-12.0). Through this study, a facile, simple, and green method has been demonstrated for preparation of stimuli-sensitive AuNPs using biocompatible polyanionic polysaccharides. Copyright © 2017 Elsevier B.V. All rights reserved.

Fabrication of triple-labeled polyelectrolyte microcapsules for localized ratiometric pH sensing.

Science.gov (United States)

Song, Xiaoxue; Li, Huanbin; Tong, Weijun; Gao, Changyou

2014-02-15

Encapsulation of pH sensitive fluorophores as reporting molecules provides a powerful approach to visualize the transportation of multilayer capsules. In this study, two pH sensitive dyes (fluorescein and oregon green) and one pH insensitive dye (rhodamine B) were simultaneously labeled on the microcapsules to fabricate ratiometric pH sensors. The fluorescence of the triple-labeled microcapsule sensors was robust and nearly independent of other intracellular species. With a dynamic pH measurement range of 3.3-6.5, the microcapsules can report their localized pH at a real time. Cell culture experiments showed that the microcapsules could be internalized by RAW 246.7 cells naturally and finally accumulated in acidic organelles with a pH value of 5.08 ± 0.59 (mean ± s.d.; n=162). Copyright © 2013 Elsevier Inc. All rights reserved.

Biobased, Internally pH-Sensitive Materials: Immobilized Yellow Fluorescent Protein as an Optical Sensor for Spatiotemporal Mapping of pH Inside Porous Matrices.

Science.gov (United States)

Consolati, Tanja; Bolivar, Juan M; Petrasek, Zdenek; Berenguer, Jose; Hidalgo, Aurelio; Guisán, Jose M; Nidetzky, Bernd

2018-02-28

The pH is fundamental to biological function and its measurement therefore crucial across all biosciences. Unlike homogenous bulk solution, solids often feature internal pH gradients due to partition effects and confined biochemical reactions. Thus, a full spatiotemporal mapping for pH characterization in solid materials with biological systems embedded in them is essential. In here, therefore, a fully biocompatible methodology for real-time optical sensing of pH within porous materials is presented. A genetically encoded ratiometric pH sensor, the enhanced superfolder yellow fluorescent protein (sYFP), is used to functionalize the internal surface of different materials, including natural and synthetic organic polymers as well as silica frameworks. By using controlled, tailor-made immobilization, sYFP is homogenously distributed within these materials and so enables, via self-referenced imaging analysis, pH measurements in high accuracy and with useful spatiotemporal resolution. Evolution of internal pH is monitored in consequence of a proton-releasing enzymatic reaction, the hydrolysis of penicillin by a penicillin acylase, taking place in solution or confined to the solid surface of the porous matrix. Unlike optochemical pH sensors, which often interfere with biological function, labeling with sYFP enables pH sensing without altering the immobilized enzyme's properties in any of the materials used. Fast response of sYFP to pH change permits evaluation of biochemical kinetics within the solid materials. Thus, pH sensing based on immobilized sYFP represents a broadly applicable technique to the study of biology confined to the internally heterogeneous environment of solid matrices.

Factors that facilitate or inhibit interest of domestic students in the engineering PhD: A mixed methods study

Science.gov (United States)

Howell Smith, Michelle C.

Given the increasing complexity of technology in our society, the United States has a growing demand for a more highly educated technical workforce. Unfortunately, the proportion of United States citizens earning a PhD in engineering has been declining and there is concern about meeting the economic, national security and quality of life needs of our country. This mixed methods sequential exploratory instrument design study identified factors that facilitate or inhibit interest in engineering PhD programs among domestic engineering undergraduate students in the United States. This study developed a testable theory for how domestic students become interested in engineering PhD programs and a measure of that process, the Exploring Engineering Interest Inventory (EEII). The study was conducted in four phases. The first phase of the study was a qualitative grounded theory exploration of interest in the engineering PhD. Qualitative data were collected from domestic engineering students, engineering faculty and industry professional who had earned a PhD in engineering. The second phase, instrument development, developed the Exploring Engineering Interest Inventory (EEII), a measurement instrument designed with good psychometric properties to test a series of preliminary hypotheses related to the theory generated in the qualitative phase. In the third phase of the study, the EEII was used to collect data from a larger sample of junior and senior engineering majors. The fourth phase integrated the findings from the qualitative and quantitative phases. Four factors were identified as being significant influences of interest in the engineering PhD: Personal characteristics, educational environment, misperceptions of the economic and personal costs, and misperceptions of engineering work. Recommendations include increasing faculty encouragement of students to pursue an engineering PhD and programming to correct the misperceptions of the costs of the engineering PhD and the

On-line monitoring of CO2 production in Lactococcus lactis during physiological pH decrease using membrane inlet mass spectrometry with dynamic pH calibration.

Science.gov (United States)

Andersen, Ann Zahle; Lauritsen, Frants Roager; Olsen, Lars Folke

2005-12-20

Monitoring CO2 production in systems, where pH is changing with time is hampered by the chemical behavior and pH-dependent volatility of this compound. In this article, we present the first method where the concentration and production rate of dissolved CO2 can be monitored directly, continuously, and quantitatively under conditions where pH changes rapidly ( approximately 2 units in 15 min). The method corrects membrane inlet mass spectrometry (MIMS) measurements of CO2 for pH dependency using on-line pH analysis and an experimentally established calibration model. It is valid within the pH range of 3.5 to 7, despite pH-dependent calibration constants that vary in a non-linear fashion with more than a factor of 3 in this interval. The method made it possible to determine the carbon dioxide production during Lactococcus lactis fermentations, where pH drops up to 3 units during the fermentation. The accuracy was approximately 5%. We used the method to investigate the effect of initial extracellular pH on carbon dioxide production during anarobic glucose fermentation by non-growing Lactocoocus lactis and demonstrated that the carbon dioxide production rate increases considerably, when the initial pH was increased from 6 to 6.8. (c) 2005 Wiley Periodicals, Inc.

pH buffers for sea water media based on the total hydrogen ion concentration scale

Science.gov (United States)

Dickson, Andrew G.

1993-01-01

Published e.m.f. values measured using the cell ? where p° = 101.325 kPa, and BH + and B are the conjugate acid-base pairs of 2-aminopyridine, 2-amino-2-hydroxymethyl-1,3-propanediol (tris), tetrahydro-1,4-isoxazine (morpholine), and 2-amino-2-methyl-1, 3-propanediol (bis), have been re-evaluated to assign pH values based on the "total" hydrogen ion concentration scale to equimolal ( m =0.04 mol kg -1) buffer solutions based on these compounds. These pH values are consistent with the best available equilibrium constants for acid-base processes in sea water and such pH buffers can be used as pH calibration standards to measure accurate values for oceanic pH on the "total" hydrogen ion pH scale. In addition, the published e.m.f. results for these various amine bases have been used to calculate their respective acidity constants on this pH scale.

Regulation of intracellular pH in cnidarians: response to acidosis in Anemonia viridis.

Science.gov (United States)

Laurent, Julien; Venn, Alexander; Tambutté, Éric; Ganot, Philippe; Allemand, Denis; Tambutté, Sylvie

2014-02-01

The regulation of intracellular pH (pHi) is a fundamental aspect of cell physiology that has received little attention in studies of the phylum Cnidaria, which includes ecologically important sea anemones and reef-building corals. Like all organisms, cnidarians must maintain pH homeostasis to counterbalance reductions in pHi, which can arise because of changes in either intrinsic or extrinsic parameters. Corals and sea anemones face natural daily changes in internal fluids, where the extracellular pH can range from 8.9 during the day to 7.4 at night. Furthermore, cnidarians are likely to experience future CO₂-driven declines in seawater pH, a process known as ocean acidification. Here, we carried out the first mechanistic investigation to determine how cnidarian pHi regulation responds to decreases in extracellular and intracellular pH. Using the anemone Anemonia viridis, we employed confocal live cell imaging and a pH-sensitive dye to track the dynamics of pHi after intracellular acidosis induced by acute exposure to decreases in seawater pH and NH₄Cl prepulses. The investigation was conducted on cells that contained intracellular symbiotic algae (Symbiodinium sp.) and on symbiont-free endoderm cells. Experiments using inhibitors and Na⁺-free seawater indicate a potential role of Na⁺/H⁺ plasma membrane exchangers (NHEs) in mediating pHi recovery following intracellular acidosis in both cell types. We also measured the buffering capacity of cells, and obtained values between 20.8 and 43.8 mM per pH unit, which are comparable to those in other invertebrates. Our findings provide the first steps towards a better understanding of acid-base regulation in these basal metazoans, for which information on cell physiology is extremely limited. © 2013 FEBS.

Post-deposition annealing temperature dependence TiO{sub 2}-based EGFET pH sensor sensitivity

Energy Technology Data Exchange (ETDEWEB)

Zulkefle, M. A., E-mail: alhadizulkefle@gmail.com; Rahman, R. A., E-mail: rohanieza.abdrahman@gmail.com; Yusoff, K. A., E-mail: khairul.aimi.yusof@gmail.com [NANO-ElecTronic Centre (NET), Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Abdullah, W. F. H., E-mail: wanfaz@salam.uitm.edu.my [Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Rusop, M., E-mail: rusop@salam.uitm.edu.my [NANO-Science Technology (NST), Institute of Science (IOS), Faculty of Applied Sciences, Universiti Teknologi MARA - UiTM, 40450 Shah Alam, Selangor (Malaysia); Herman, S. H., E-mail: hana1617@salam.uitm.edu.my [Core of Frontier Materials & Industry Applications, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia)

2016-07-06

EGFET pH sensor is one type of pH sensor that is used to measure and determine pH of a solution. The sensing membrane of EGFET pH sensor plays vital role in the overall performance of the sensor. This paper studies the effects of different annealing temperature of the TiO{sub 2} sensing membranes towards sensitivity of EGFET pH sensor. Sol-gel spin coating was chosen as TiO{sub 2} deposition techniques since it is cost-effective and produces thin film with uniform thickness. Deposited TiO{sub 2} thin films were then annealed at different annealing temperatures and then were connected to the gate of MOSFET as a part of the EGFET pH sensor structure. The thin films now act as sensing membranes of the EGFET pH sensor and sensitivity of each sensing membrane towards pH was measured. From the results it was determined that sensing membrane annealed at 300 °C gave the highest sensitivity followed by sample annealed at 400 °C and 500 °C.

OZONE BLEACHING AT NEUTRAL PH – A NEW CONCEPT

Directory of Open Access Journals (Sweden)

Fernando de Carvalho

2010-08-01

Full Text Available The effect of medium consistency ozone stage pH was evaluated for brown and oxygen delignified eucalyptus kraft pulp samples obtained from VCP - Luiz Antônio pulp mill. These samples were used as such or previously treated with the hot acid stage (A. The main objective of this study was to determine the viability of increasing the ozone stage pH aiming at decreasing bleaching variable costs. The ozone stage was studied in the pH range of 2.5-9.0, taking into account some important variables which affect ozone bleaching: (1 pulp kappa number entering the ozone stage, (2 reactivity of ozone towards lignin versus hexenuronic acids (HexA´s, (3 pulp treatments prior to ozone stage (acid hydrolysis, and (4 pulp treatments after the ozone stage (extraction or a chlorine dioxide stage.  Therefore, the impact of ozone stage pH was investigated in bleaching process such as Z/DEop vs AZ/DEop, Z/DEopD vs AZ/DEopD, Z/E vs AZ/E. The results were interpreted based on ozone stage efficiency and selectivity, and overall bleaching performance measured by the total bleaching chemical consumption required to achieve full brightness, pulp quality and environmental impact. It was concluded that the increase of ozone stage pH from 2.5 to 7.0 has a slightly negative impact on the efficiency and selectivity, measured after Z/DEop sequence, but this effect is not expressive in the end of Z/DEopD bleaching sequence. The increase of ozone stage pH from 2.5 to 7.0 in the sequence Z/DEopD is cost-effective at industrial level because it represents expressive reduction of sulphuric acid and caustic soda demand for pH control in the bleaching plant. These gain areas achieved without any significant changes in pulp quality and effluent load discharge. Nevertheless, the increase of ozone stage pH from 2.5 to 7.0 has a very high negative impact on the efficiency and selectivity for the Z/E and AZ/E processes and it is not recommended in such cases.

Fine-particle pH for Beijing winter haze as inferred from different thermodynamic equilibrium models

Directory of Open Access Journals (Sweden)

S. Song

2018-05-01

Full Text Available pH is an important property of aerosol particles but is difficult to measure directly. Several studies have estimated the pH values for fine particles in northern China winter haze using thermodynamic models (i.e., E-AIM and ISORROPIA and ambient measurements. The reported pH values differ widely, ranging from close to 0 (highly acidic to as high as 7 (neutral. In order to understand the reason for this discrepancy, we calculated pH values using these models with different assumptions with regard to model inputs and particle phase states. We find that the large discrepancy is due primarily to differences in the model assumptions adopted in previous studies. Calculations using only aerosol-phase composition as inputs (i.e., reverse mode are sensitive to the measurement errors of ionic species, and inferred pH values exhibit a bimodal distribution, with peaks between −2 and 2 and between 7 and 10, depending on whether anions or cations are in excess. Calculations using total (gas plus aerosol phase measurements as inputs (i.e., forward mode are affected much less by these measurement errors. In future studies, the reverse mode should be avoided whereas the forward mode should be used. Forward-mode calculations in this and previous studies collectively indicate a moderately acidic condition (pH from about 4 to about 5 for fine particles in northern China winter haze, indicating further that ammonia plays an important role in determining this property. The assumed particle phase state, either stable (solid plus liquid or metastable (only liquid, does not significantly impact pH predictions. The unrealistic pH values of about 7 in a few previous studies (using the standard ISORROPIA model and stable state assumption resulted from coding errors in the model, which have been identified and fixed in this study.

A Fiber Optic Ammonia Sensor Using a Universal pH Indicator

Directory of Open Access Journals (Sweden)

Adolfo J. Rodríguez

2014-02-01

Full Text Available A universal pH indicator is used to fabricate a fiber optic ammonia sensor. The advantage of this pH indicator is that it exhibits sensitivity to ammonia over a broad wavelength range. This provides a differential response, with a valley around 500 nm and a peak around 650 nm, which allows us to perform ratiometric measurements. The ratiometric measurements provide not only an enhanced signal, but can also eliminate any external disturbance due to humidity or temperature fluctuations. In addition, the indicator is embedded in a hydrophobic and gas permeable polyurethane film named Tecoflex®. The film provides additional advantages to the sensor, such as operation in dry environments, efficient transport of the element to be measured to the sensitive area of the sensor, and prevent leakage or detachment of the indicator. The combination of the universal pH indicator and Tecoflex® film provides a reliable and robust fiber optic ammonia sensor.

A Fiber Optic Ammonia Sensor Using a Universal pH Indicator

Science.gov (United States)

Rodríguez, Adolfo J.; Zamarreño, Carlos R.; Matías, Ignacio R.; Arregui, Francisco. J.; Domínguez Cruz, Rene F.; May-Arrioja, Daniel. A.

2014-01-01

A universal pH indicator is used to fabricate a fiber optic ammonia sensor. The advantage of this pH indicator is that it exhibits sensitivity to ammonia over a broad wavelength range. This provides a differential response, with a valley around 500 nm and a peak around 650 nm, which allows us to perform ratiometric measurements. The ratiometric measurements provide not only an enhanced signal, but can also eliminate any external disturbance due to humidity or temperature fluctuations. In addition, the indicator is embedded in a hydrophobic and gas permeable polyurethane film named Tecoflex®. The film provides additional advantages to the sensor, such as operation in dry environments, efficient transport of the element to be measured to the sensitive area of the sensor, and prevent leakage or detachment of the indicator. The combination of the universal pH indicator and Tecoflex® film provides a reliable and robust fiber optic ammonia sensor. PMID:24583969

Meet EPA Scientist Jordan West, Ph.D.

Science.gov (United States)

Jordan West, Ph.D. is an aquatic ecologist at EPA. Her areas of expertise include freshwater & marine ecology, climate change impacts and adaptation, resilience and threshold theory, environmental risk assessment, expert elicitation & stakeholder processes

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.

BSA-coated nanoparticles for improved SERS-based intracellular pH sensing.

Science.gov (United States)

Zheng, Xiao-Shan; Hu, Pei; Cui, Yan; Zong, Cheng; Feng, Jia-Min; Wang, Xin; Ren, Bin

2014-12-16

Local microenvironment pH sensing is one of the key parameters for the understanding of many biological processes. As a noninvasive and high sensitive technique, surface-enhanced Raman spectroscopy (SERS) has attracted considerable interest in the detection of the local pH of live cells. We herein develop a facile way to prepare Au-(4-MPy)-BSA (AMB) pH nanosensor. The 4-MPy (4-mercaptopyridine) was used as the pH sensing molecule. The modification of the nanoparticles with BSA not only provides a high sensitive response to pH changes ranging from pH 4.0 to 9.0 but also exhibits a high sensitivity and good biocompatibility, stability, and reliability in various solutions (including the solutions of high ionic strength or with complex composition such as the cell culture medium), both in the aggregation state or after long-term storage. The AMB pH nanosensor shows great advantages for reliable intracellular pH analysis and has been successfully used to monitor the pH distribution of live cells and can address the grand challenges in SERS-based pH sensing for practical biological applications.

Long photoperiods sustain high pH in Arctic kelp forests

DEFF Research Database (Denmark)

Krause-Jensen, Dorte; Marbà, Núria; Sanz-Martin, M.

2016-01-01

Concern on the impacts of ocean acidification on calcifiers, such as bivalves, sea urchins, and foraminifers, has led to efforts to understand the controls on pH in their habitats, which include kelp forests and seagrass meadows. The metabolism of these habitats can lead to diel fluctuation in pH...... with increases during the day and declines at night, suggesting no net effect on pH at time scales longer than daily. We examined the capacity of subarctic and Arctic kelps to up-regulate pH in situ and experimentally tested the role of photoperiod in determining the capacity of Arctic macrophytes to up......-regulate pH. Field observations at photoperiods of 15 and 24 hours in Greenland com- bined with experimental manipulations of photoperiod show that photoperiods longer than 21 hours, characteristic of Arctic summers, are conducive to sustained up-regulation of pH by kelp photosynthesis. We report a gradual...

Ratiometric Imaging of Extracellular pH in Dental Biofilms

DEFF Research Database (Denmark)

Schlafer, Sebastian; Dige, Irene

2016-01-01

The pH in bacterial biofilms on teeth is of central importance for dental caries, a disease with a high worldwide prevalence. Nutrients and metabolites are not distributed evenly in dental biofilms. A complex interplay of sorption to and reaction with organic matter in the biofilm reduces...... the diffusion paths of solutes and creates steep gradients of reactive molecules, including organic acids, across the biofilm. Quantitative fluorescent microscopic methods, such as fluorescence life time imaging or pH ratiometry, can be employed to visualize pH in different microenvironments of dental biofilms...... allows monitoring both vertical and horizontal pH gradients in real-time without mechanically disturbing the biofilm. However, care must be taken to differentiate accurately between extra- and intracellular compartments of the biofilm. Here, the ratiometric dye, seminaphthorhodafluor-4F 5-(and-6...

Effect of nitrogen form and pH of nutrient solution on the changes in pH and EC of spinach rhizosphere in hydroponic culture

OpenAIRE

M. Parsazadeh; N. Najafi

2011-01-01

In this study, the effect of nitrate to ammonium ratio and pH of nutrient solution on the changes in pH and EC of rhizosphere during spinach growth period in perlite culture, under greenhouse conditions, was investigated. A split factorial experiment in a completely randomized design with four replications was conducted with three factors including nutrient solution’s pH in three levels (4.5, 6.5 and 8), nitrate to ammonium ratio of nutrient solution in five levels (100:0, 75:25, 50:50, 25:75...

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.

[pH values in the pharynx of the patients presenting with compromised nasal breathing of inflammatory and non-inflammatory genesis concomitant with gastroesophageal reflux disease].

Science.gov (United States)

Subbotina, M V; Temnikova, I V; Onuchina, E V

2015-01-01

The objective of the present study was to estimate the influence of gastroesophageal reflux disease (GERD) on the pH values in the pharynx and nose. It included 87 patients at the age varying from 18 to 81 years admitted to the Irkutsk-based Railway Clinical Hospital and allocated to four groups. Group 1 was comprised of 25 patients presenting with gastroesophageal reflux disease and chronic rhinosinusitis (CRS), group 2 consisted of 29 patients with CRS in the absence of GERD, group 3 included 22 patients with nasal septum deformations (NSD) and GERD, group 4 included 11 patients with NSD and motor rhinitis without GERD. The control group was formed from 10 volunteers. pH was measured by the contact method with the use ofEkokhim indicator paper. Gastroesophageal reflux disease was diagnosed following the recommendations of the Montreal consensus. It was shown that pH values in the pharynx of the patients with compromised nasal breathing of any origin in combination with GERD were lower than in the absence of GERD and in the healthy volunteers. The study groups did not differ in terms of pH values in the nasal cavity. It is concluded that pH values 4 or lower may serve as the criterion for pharyngo-laryngeal reflux (PLR) concomitant with HERD while pH 5 occurs more frequently in the patients with compromised nasal breathing of any etiology, regardless of the presence or absence of GERD.Disordered nasal breathing of any genesis in the patients presenting with gastroesophageal reflux disease was associated with the feeling of the lump in the throat, congestion of the respiratory tract and the nose, pain in the ears, cardialgia, and irregular heartbeat. It isrecommended to use pH measurements as a criterion for diagnostics of pharyngo-laryngeal reflux in the patients presenting with gastroesophageal reflux disease.

Hubungan antara pH Susu dengan Jumlah Sel Somatik Sebagai Parameter Mastitis Subklinik

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M. Sudarwanto

2008-08-01

Full Text Available The aim of this research was to measure the relationship of the pH value to the somatic cell count as a parameter of sub clinical mastitis detection. Two hundreds quarter milk samples were used in this research and the test (the pH value, IPB-1 mastitis test and Breed method was done in parallel way. The results showed that 152 samples from 200 samples (76% tested with Breed method came from the herds which suffered from sub-clinical mastitis and with IPB-1 test showed that 145 (72.5% of the samples had positive reaction. Using pH meter, it showed that 44 samples (22 % had pH > 6.75, presumed suffered from sub-clinical mastitis and 2 samples (1% showed pH < 6.30 (6.25 and 6.28. At the same time, these two samples showed a negative reaction with IPB-1 test and had somatic cell count of 360,000/ml and 280,000/ml, each. It also showed that there was a close relationship between pH value and IPB-1 test. The conclusion of this research was that the measurement of pH value was not a sensitive method for detecting sub-clinical mastitis.

In situ 2D maps of pH shifts across brass–lead galvanic joints using microelectrodes

International Nuclear Information System (INIS)

Ma, Xiangmeng; Lee, Woo Hyoung; Lytle, Darren A

2017-01-01

Galvanic corrosion in drinking water distribution systems, such as conditions following partial lead service line replacement, can be a significant source of lead in tap water. The objective of this work was to measure the pH directly near metal surfaces using a novel experimental tool in order to understand the water chemistry at a lead-containing galvanic couple in drinking water. Specifically, pH microprofiles in the proximity of corroding metal surfaces were measured using a microelectrode to construct detailed in situ 2D spatial maps of the pH across a galvanic couple at 100 µ m above the metal’s surface under flowing and stagnation conditions. The opposite pH trend was directly observed across the galvanic couple under flow and stagnation conditions. Water stagnation resulted in a pH at the anode (leaded solder) of 1.5 pH units lower than the bulk water pH (9.0) and as much as 2.5 pH units lower than the cathode (brass). These conditions can enhance lead release at the anode, which reflects different anodic–cathodic relationships of coupled metals primarily controlled by water flow. Most importantly, this work has demonstrated the ability to make real pH measurement at the surface of corroding metals using a novel microelectrode approach. (paper)

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.

Three dimensional graphene transistor for ultra-sensitive pH sensing directly in biological media

International Nuclear Information System (INIS)

Ameri, Shideh Kabiri; Singh, Pramod K.; Sonkusale, Sameer R.

2016-01-01

In this work, pH sensing directly in biological media using three dimensional liquid gated graphene transistors is presented. The sensor is made of suspended network of graphene coated all around with thin layer of hafnium oxide (HfO_2), showing high sensitivity and sensing beyond the Debye-screening limit. The performance of the pH sensor is validated by measuring the pH of isotonic buffered, Dulbecco's phosphate buffered saline (DPBS) solution, and of blood serum derived from Sprague-Dawley rat. The pH sensor shows high sensitivity of 71 ± 7 mV/pH even in high ionic strength media with molarities as high as 289 ± 1 mM. High sensitivity of this device is owing to suspension of three dimensional graphene in electrolyte which provides all around liquid gating of graphene, leading to higher electrostatic coupling efficiency of electrolyte to the channel and higher gating control of transistor channel by ions in the electrolyte. Coating graphene with hafnium oxide film (HfO_2) provides binding sites for hydrogen ions, which results in higher sensitivity and sensing beyond the Debye-screening limit. The 3D graphene transistor offers the possibility of real-time pH measurement in biological media without the need for desaltation or sample preparation. - Graphical abstract: (a) Test setup – Direct rat blood serum pH measurements (b) Measured transfer characteristics of the transistor for blood serum at different pH values, and (c) Zoomed in version around direct point. - Highlights: • A three-dimensional graphene transistor for pH sensing is presented. • It shows sensitivity of 71 ± 7 mV/pH even in high ionic strength media. • High sensitivity attributed to 3D foam structure and all-around liquid gating. • Enables real-time pH sensing in biological media without need of desaltation.

Three dimensional graphene transistor for ultra-sensitive pH sensing directly in biological media

Energy Technology Data Exchange (ETDEWEB)

Ameri, Shideh Kabiri; Singh, Pramod K.; Sonkusale, Sameer R., E-mail: sameer@ece.tufts.edu

2016-08-31

In this work, pH sensing directly in biological media using three dimensional liquid gated graphene transistors is presented. The sensor is made of suspended network of graphene coated all around with thin layer of hafnium oxide (HfO{sub 2}), showing high sensitivity and sensing beyond the Debye-screening limit. The performance of the pH sensor is validated by measuring the pH of isotonic buffered, Dulbecco's phosphate buffered saline (DPBS) solution, and of blood serum derived from Sprague-Dawley rat. The pH sensor shows high sensitivity of 71 ± 7 mV/pH even in high ionic strength media with molarities as high as 289 ± 1 mM. High sensitivity of this device is owing to suspension of three dimensional graphene in electrolyte which provides all around liquid gating of graphene, leading to higher electrostatic coupling efficiency of electrolyte to the channel and higher gating control of transistor channel by ions in the electrolyte. Coating graphene with hafnium oxide film (HfO{sub 2}) provides binding sites for hydrogen ions, which results in higher sensitivity and sensing beyond the Debye-screening limit. The 3D graphene transistor offers the possibility of real-time pH measurement in biological media without the need for desaltation or sample preparation. - Graphical abstract: (a) Test setup – Direct rat blood serum pH measurements (b) Measured transfer characteristics of the transistor for blood serum at different pH values, and (c) Zoomed in version around direct point. - Highlights: • A three-dimensional graphene transistor for pH sensing is presented. • It shows sensitivity of 71 ± 7 mV/pH even in high ionic strength media. • High sensitivity attributed to 3D foam structure and all-around liquid gating. • Enables real-time pH sensing in biological media without need of desaltation.

Direct measurement of CO2 solubility and pH in NaCl hydrothermal solutions by combining in-situ potentiometry and Raman spectroscopy up to 280 °C and 150 bar

Science.gov (United States)

Truche, Laurent; Bazarkina, Elena F.; Berger, Gilles; Caumon, Marie-Camille; Bessaque, Gilles; Dubessy, Jean

2016-03-01

The in-situ monitoring of aqueous solution chemistry at elevated temperatures and pressures is a major challenge in geochemistry. Here, we combined for the first time in-situ Raman spectroscopy for concentration measurements and potentiometry for pH measurement in a single hydrothermal cell equipped with sampling systems and operating under controlled conditions of temperature and pressure. Dissolved CO2 concentration and pH were measured at temperatures up to 280 °C and pressures up to 150 bar in the H2O-CO2 and H2O-CO2-NaCl systems. A Pitzer specific-ion-interaction aqueous model was developed and confirmed the accuracy and consistency of the measurements, at least up to 250 °C. The revised Pitzer parameters for the H2O-CO2-NaCl system were formatted for the Phreeqc geochemical software. Significant changes with respect to the Pitzer.dat database currently associated with Phreeqc were observed. The new model parameters are now available for further applications. The Raman and pH probes tested here may also be applied to field monitoring of hydrothermal springs, geothermal wells, and oil and gas boreholes.

A geometric process model for M/PH(M/PH)/1/K queue with new service machine procurement lead time

Science.gov (United States)

Yu, Miaomiao; Tang, Yinghui; Fu, Yonghong

2013-06-01

In this article, we consider a geometric process model for M/PH(M/PH)/1/K queue with new service machine procurement lead time. A maintenance policy (N - 1, N) based on the number of failures of the service machine is introduced into the system. Assuming that a failed service machine after repair will not be 'as good as new', and the spare service machine for replacement is only available by an order. More specifically, we suppose that the procurement lead time for delivering the spare service machine follows a phase-type (PH) distribution. Under such assumptions, we apply the matrix-analytic method to develop the steady state probabilities of the system, and then we obtain some system performance measures. Finally, employing an important Lemma, the explicit expression of the long-run average cost rate for the service machine is derived, and the direct search method is also implemented to determine the optimal value of N for minimising the average cost rate.

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.

The Influence of Polymerization Condition to Optical Properties of Poly-o-toludine Films for PH Sensor Application

Directory of Open Access Journals (Sweden)

Yanti Sabarinah

2006-04-01

Full Text Available Properties of poly-o-toludine film strongly bonded to non polar substrate was studied for application as optical pH sensor. Characterization of film in various pH value is carried out by recording absorbance curve using uv-visible spectrophotometer. All poly-o-toluidine film was then found to be applicable as optical pH sensor in the pH range of 2.0- 6.0. Further computational processing by means of curve fitting into logaritmic trend will allow expansion of measurement to the pH range of 2.0-8.0. Sensitivity of pH response was highest in poly-o-toluidine film fabricate at HCl 1.0 M and at 12 hours of dipping time. This paper also studied hysteresis effect in pH response. It was concluded that poly-o-toluidine salt exposed to basic pH will not be easily regenerated. For this reason, poly-o-toluidine film will only be suitable for single usage of pH measurement.

Salivary pH levels and caries among siblings and parents within families.

Science.gov (United States)

Basch, Yaffa; Peretz, Benjamin

2013-01-01

High level of caries activity is related to organisms in the dental plaque with high acidogenesis capacity. To test salivary pH in children of the same family and compare it with their caries status. To compare pH levels between children and their parents. To examine the relationship between pH and caries status among children of the same family and their parents. We examined 123 children and adolescents aged 3-18, (73 boys and 50 girls) and 33 adults, (12 men and 21 women), parents of these children. Caries status was examined clinically, using DMF index. Salivary pH measurements were made by a digital pH meter. Among adults, increase in patient age led to increased DMF (p = 0.005). The higher the pH, the lower the DMF (p = 0.037). Among men, DMF was lower by 3 compared to women (p = 0.049). Children's pH correlated with the parents' (p = 0.004). Children's DMF correlated to their pH (p = 0.001). Children's pH was the best predictor of their DMF (R2 = 0.309, p = 0.001). Among children, the higher the pH, the lower the DMFT. Children's pH was the best predictor of their DMF.