Stretchable wireless system for sweat pH monitoring.

PubMed

Dang, Wenting; Manjakkal, Libu; Navaraj, William Taube; Lorenzelli, Leandro; Vinciguerra, Vincenzo; Dahiya, Ravinder

2018-06-01

Sensor-laden wearable systems that are capable of providing continuous measurement of key physiological parameters coupled with data storage, drug delivery and feedback therapy have attracted huge interest. Here we report a stretchable wireless system for sweat pH monitoring, which is able to withstand up to 53% uniaxial strain and more than 500 cycles to 30% strain. The stretchability of the pH sensor patch is provided by a pair of serpentine-shaped stretchable interconnects. The pH sensing electrode is made of graphite-polyurethane composite, which is suitable for biosensor application. The sensing patch validated through in-depth electrochemical studies, exhibits a pH sensitivity of 11.13 ± 5.8 mV/pH with a maximum response time of 8 s. Interference study of ions and analyte (Na + , K + and glucose) in test solutions shows negligible influence on the pH sensor performance. The pH data can be wirelessly and continuously transmitted to smartphone through a stretchable radio-frequency-identification antenna, of which the radiating performance is stable under 20% strain, as proved by vector network analyzer measurement. To evaluate the full system, the pH value of a human sweat equivalent solution has been measured and wirelessly transmitted to a custom-developed smart phone App. Copyright © 2018 Elsevier B.V. All rights reserved.

Design of aquaponics water monitoring system using Arduino microcontroller

NASA Astrophysics Data System (ADS)

Murad, S. A. Z.; Harun, A.; Mohyar, S. N.; Sapawi, R.; Ten, S. Y.

2017-09-01

This paper describes the design of aquaponics water monitoring system using Arduino microcontroller. Arduino Development Environment (IDE) software is used to develop a program for the microcontroller to communicate with multiple sensors and other hardware. The circuit of pH sensor, temperature sensor, water sensor, servo, liquid crystal displays (LCD), peristaltic pump, solar and Global System for Mobile communication (GSM) are constructed and connected to the system. The system powered by a rechargeable battery using solar energy. When the results of pH, temperature and water sensor are out of range, a notification message will be sent to a mobile phone through GSM. If the pH of water is out of range, peristaltic pump is automatic on to maintain back the pH value of water. The water sensor is fixed in the siphon outlet water flow to detect water flow from grow bed to the fish tank. In addition, servo is used to auto feeding the fish for every 12 hours. Meanwhile, the LCD is indicated the pH, temperature, siphon outlet water flow and remaining time for the next feeding cycle. The pH and temperature of water are set in the ranges of 6 to 7 and 25 °C to 30 °C, respectively.

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

PubMed

Azzam, Rimon Sobhi; Sallum, Rubens A A; Brandão, Jeovana Ferreira; Navarro-Rodriguez, Tomás; Nasi, Ary

2012-01-01

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. 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. 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. 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). 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.

Hydrogel-coated fiber Bragg grating sensor for pH monitoring

NASA Astrophysics Data System (ADS)

Pabbisetti, Vayu Nandana Kishore; Madhuvarasu, Sai Shankar

2016-06-01

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

Design and validation of a new ratiometric intracellular pH imaging probe using lanthanide-doped upconverting nanoparticles.

PubMed

Du, Shuoren; Hernández-Gil, Javier; Dong, Hao; Zheng, Xiaoyu; Lyu, Guangming; Bañobre-López, Manuel; Gallo, Juan; Sun, Ling-Dong; Yan, Chun-Hua; Long, Nicholas J

2017-10-17

pH homeostasis is strictly controlled at a subcellular level. A deregulation of the intra/extra/subcellular pH environment is associated with a number of diseases and as such, the monitoring of the pH state of cells and tissues is a valuable diagnostic tool. To date, only a few tools have been developed to measure the pH in living cells with the spatial resolution needed for intracellular imaging. Among the techniques available, only optical imaging offers enough resolution and biocompatibility to be proposed for subcellular pH monitoring. We present herein a ratiometric probe based on upconversion nanoparticles modified with a pH sensitive moiety for the quantitative imaging of pH at the subcellular level in living cells. This system provides the properties required for live cell quantitative imaging i.e. positive cellular uptake, biocompatibility, long wavelength excitation, sensitive response to pH within a biologically relevant range, and self-referenced signal.

Water quality monitor. [spacecraft potable water

NASA Technical Reports Server (NTRS)

West, S.; Crisos, J.; Baxter, W.

1979-01-01

The preprototype water quality monitor (WQM) subsystem was designed based on a breadboard monitor for pH, specific conductance, and total organic carbon (TOC). The breadboard equipment demonstrated the feasibility of continuous on-line analysis of potable water for a spacecraft. The WQM subsystem incorporated these breadboard features and, in addition, measures ammonia and includes a failure detection system. The sample, reagent, and standard solutions are delivered to the WQM sensing manifold where chemical operations and measurements are performed using flow through sensors for conductance, pH, TOC, and NH3. Fault monitoring flow detection is also accomplished in this manifold assembly. The WQM is designed to operate automatically using a hardwired electronic controller. In addition, automatic shutdown is incorporated which is keyed to four flow sensors strategically located within the fluid system.

Advanced Biotelemetry Systems for Space Life Sciences: PH Telemetry

NASA Technical Reports Server (NTRS)

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.

Monitoring the Collapse of pH-Sensitive Liposomal Nanocarriers and Environmental pH Simultaneously: A Fluorescence-Based Approach.

PubMed

Draffehn, Sören; Kumke, Michael U

2016-05-02

Nowadays, the encapsulation of therapeutic compounds in so-called carrier systems is a very smart method to achieve protection as well as an improvement of their temporal and spatial distribution. After the successful transport to the point of care, the delivery has to be released under controlled conditions. To monitor the triggered release from the carrier, we investigated different fluorescent probes regarding their response to the pH-induced collapse of pH-sensitive liposomes (pHSLip), which occurs when the environmental pH falls below a critical value. Depending on the probe, the fluorescence decay time as well as fluorescence anisotropy can be used equally as key parameters for monitoring the collapse. Especially the application of a fluorescein labeled fatty acid (fPA) enabled the monitoring of the pHSLips collapse and the pH of its microenvironment simultaneously without interference. Varying the pH in the range of 3 < pH < 9, anisotropy data revealed the critical pH value at which the collapse of the pHSLips occurs. Complementary methods, e.g., fluorescence correlation spectroscopy and dynamic light scattering, supported the analysis based on the decay time and anisotropy. Additional experiments with varying incubation times yielded information on the kinetics of the liposomal collapse.

Technical note: development and testing of a radio transmission pH measurement system for continuous monitoring of ruminal pH in cows.

PubMed

Sato, Shigeru; Mizuguchi, Hitoshi; Ito, Kazunori; Ikuta, Kentaro; Kimura, Atushi; Okada, Keiji

2012-03-01

An indwelling ruminal pH system has been used for the continuous recording of ruminal pH to evaluate subacute ruminal acidosis (SARA) in dairy cows. However this system does not allow the field application. The objective of this study was to develop a new radio transmission pH measurement system, and to assess its performance and usefulness in a continuous evaluation of ruminal pH for use on commercial dairy farms. The radio transmission pH measurement system consists of a wireless pH sensor, a data measurement receiver, a relay unit, and a personal computer installed special software. The pH sensor is housed in a bullet shaped bolus, which also encloses a pH amplifier circuit, a central processing unit (CPU) circuit, a radio frequency (RF) circuit, and a battery. The mean variations of the measurements by the glass pH electrode were +0.20 (n=10) after 2 months of continuous recording, compared to the values confirmed by standard pH solutions for pH 4 and pH 7 at the start of the recording. The mean lifetime of the internal battery was 2.5 months (n=10) when measurements were continuously transmitted every 10 min. Ruminal pH recorded by our new system was compared to that of the spot sampling of ruminal fluid. The mean pH for spot sampling was 6.36 ± 0.55 (n=96), and the mean pH of continuous recording was 6.22 ± 0.54 (n=96). There was a good correlation between continuous recording and spot sampling (r=0.986, P<0.01). We also examined whether our new pH system was able to detect experimentally induced ruminal acidosis in cows and to record long-term changes in ruminal pH. In the cows fed acidosis-inducing diets, the ruminal pH dropped markedly during the first 2h following the morning feeding, and decreased moreover following the evening feeding, with many pulse-like pH changes. The pH of the cows showed the lowest values of 5.3-5.2 in the midnight time period and it recovered to the normal value by the next morning feeding. In one healthy periparturient cow, the circadian changes in ruminal pH were observed as a constant pattern in the pre-parturient period, however that pattern became variable in the post-partum period. The frequency of the ruminal pH lower than 5.5 increased markedly 3 and 4 days after parturition. We demonstrated the possible application of a radio transmission pH measurement system for the assessment and monitoring of the ruminal pH of cows. Our new system might contribute to accurate assessment and prevention of SARA. Copyright © 2011 Elsevier B.V. All rights reserved.

40 CFR Table 41 to Subpart Uuu of... - Requirements for Installation, Operation, and Maintenance of Continuous Parameter Monitoring Systems

Code of Federal Regulations, 2010 CFR

2010-07-01

...), you shall meet each requirement in the following table that applies to you. If you use . . . You shall . . . 1. pH strips Use pH strips with an accuracy of ±10 percent. 2. Colormetric tube sampling system Use a colormetric tube sampling system with a printed numerical scale in ppmv, a standard measurement...

Recent developments in water quality monitoring for Space Station reclaimed wastewaters

NASA Technical Reports Server (NTRS)

Small, John W.; Verostko, Charles E.; Linton, Arthur T.; Burchett, Ray

1987-01-01

This paper discusses the recent developments in water quality monitoring for Space Station reclaimed wastewaters. A preprototype unit that contains an ultraviolet absorbance organic carbon monitor integrated with pH and conductivity sensors is presented. The preprototype has provisions for automated operation and is a reagentless flow-through system without any gas/liquid interfaces. The organic carbon monitor detects by utraviolet absorbance the organic impurities in reclaimed wastewater which may be correlated to the organic carbon content of the water. A comparison of the preprototype organic carbon detection values with actual total organic carbon measurements is presented. The electrolyte double junction concept for the pH sensor and fixed electrodes for both the pH and conductivity sensors are discussed. In addition, the development of a reagentless organic carbon analyzer that incorporates ultraviolet oxidation and infrared detection is presented. Detection sensitivities, hardware development, and operation are included.

Development of a laboratory prototype water quality monitoring system suitable for use in zero gravity

NASA Technical Reports Server (NTRS)

Misselhorn, J. E.; Witz, S.; Hartung, W. H.

1973-01-01

The development of a laboratory prototype water quality monitoring system for use in the evaluation of candidate water recovery systems and for study of techniques for measuring potability parameters is reported. Sensing techniques for monitoring of the most desirable parameters are reviewed in terms of their sensitivities and complexities, and their recommendations for sensing techniques are presented. Rationale for selection of those parameters to be monitored (pH, specific conductivity, Cr(+6), I2, total carbon, and bacteria) in a next generation water monitor is presented along with an estimate of flight system specifications. A master water monitor development schedule is included.

Evaluation of mitochondrial activity by two-photon absorption with near-field multioptical fiber probes

NASA Astrophysics Data System (ADS)

Kanazashi, Yasuaki; Takara, Naoshi; Iwami, Kentaro; Ohta, Yoshihiro; Umeda, Norihiro

2018-04-01

pH measurements enable the direct monitoring and evaluation of mitochondrial activity. We constructed a scanning near-field optical microscopy system with multioptical fiber probes using the two-photon absorption of a pH-sensitive fluorescent dye, SNARF-4F, to measure the activity difference of mitochondrial aggregates. pH can be monitored through the fluorescence intensity ratio (FIR) of SNARF-4F. We derived a calibration curve of the FIR as a function of pH. The FIR dynamic responses were measured by adding hydrochloric acid to the buffer solution. Using the developed system, we simultaneously measured the pH changes at two different locations in the SNARF-4F solution. Mitochondrial samples were prepared using optical tweezers to control the number and position of mitochondria. Mitochondrial pH changes (ΔpH) between 0.05 and 0.57 were observed after adding a nutritional supplement (malate and glutamate). In addition, in the comparative experiment on the activities of two mitochondrial populations, the obtained result suggested that the activity differs depending on the difference in the number of mitochondria.

An electrochemical approach to monitor pH change in agar media during plant tissue culture.

PubMed

Wang, Min; Ha, Yang

2007-05-15

In this work, metal oxide microelectrodes were developed to monitor pH change in agar media during plant tissue culture. An antimony wire was produced by a new approach "capillary melt method". The surface of the obtained antimony wire was oxidized in a potassium nitrate melt to fabricate an antimony oxide film for pH sensing. Characterization results show that the oxide layer grown on the wire surface consists of Sb(2)O(3) crystal phase. The sensing response, open-circuit potential, of the electrode has a good linear relationship (R(2)=1.00) with pH value of the test solution. Adding organic compounds into the test media would not affect the linear relationship, although the slope of the lines varied with different ingredients added. The antimony oxide electrodes were employed to continuously monitor pH change of agar culture media during a 2-week plant tissue culture of Dendrobium candidum. The antimony oxide electrode fabricated this way has the advantages of low cost, easy fabrication, fast response, and almost no contamination introduced into the system. It would be suitable for in situ and continuous pH measurement in many bio applications.

Development of Online Spectroscopic pH Monitoring for Nuclear Fuel Reprocessing Plants: Weak Acid Schemes.

PubMed

Casella, Amanda J; Ahlers, Laura R H; Campbell, Emily L; Levitskaia, Tatiana G; Peterson, James M; Smith, Frances N; Bryan, Samuel A

2015-05-19

In nuclear fuel reprocessing, separating trivalent minor actinides and lanthanide fission products is extremely challenging and often necessitates tight pH control in TALSPEAK (Trivalent Actinide-Lanthanide Separation by Phosphorus reagent Extraction from Aqueous Komplexes) separations. In TALSPEAK and similar advanced processes, aqueous pH is one of the most important factors governing the partitioning of lanthanides and actinides between an aqueous phase containing a polyaminopolycarboxylate complexing agent and a weak carboxylic acid buffer and an organic phase containing an acidic organophosphorus extractant. Real-time pH monitoring would significantly increase confidence in the separation performance. Our research is focused on developing a general method for online determination of the pH of aqueous solutions through chemometric analysis of Raman spectra. Spectroscopic process-monitoring capabilities, incorporated in a counter-current centrifugal contactor bank, provide a pathway for online, real-time measurement of solution pH. The spectroscopic techniques are process-friendly and can be easily configured for online applications, whereas classic potentiometric pH measurements require frequent calibration/maintenance and have poor long-term stability in aggressive chemical and radiation environments. Raman spectroscopy discriminates between the protonated and deprotonated forms of the carboxylic acid buffer, and the chemometric processing of the Raman spectral data with PLS (partial least-squares) regression provides a means to quantify their respective abundances and therefore determine the solution pH. Interpretive quantitative models have been developed and validated under a range of chemical composition and pH conditions using a lactic acid/lactate buffer system. The developed model was applied to new spectra obtained from online spectral measurements during a solvent extraction experiment using a counter-current centrifugal contactor bank. The model predicted the pH of this validation data set within 11% for pH > 2, thus demonstrating that this technique could provide the capability of monitoring pH online in applications such as nuclear fuel reprocessing.

Development of an On-Demand, Generic, Drug-Delivery System

DTIC Science & Technology

1985-08-06

systems Two systems were evaluated for CO2 evolution. The first of these was an enzymatic system based on urea and urease . The second system was based...PHM 84 Research pH Meter was used te monitor pH. Solutions of various buffer concen- trations and pHs were prepared for each buffer system. One urease ...Measurement of carbon dio~ide production was accomplished using the apparatus shown in Figure 2. Carbon dioxide was generated by putting a urease tablet in the

Flexible pH-Sensing Hydrogel Fibers for Epidermal Applications.

PubMed

Tamayol, Ali; Akbari, Mohsen; Zilberman, Yael; Comotto, Mattia; Lesha, Emal; Serex, Ludovic; Bagherifard, Sara; Chen, Yu; Fu, Guoqing; Ameri, Shideh Kabiri; Ruan, Weitong; Miller, Eric L; Dokmeci, Mehmet R; Sonkusale, Sameer; Khademhosseini, Ali

2016-03-01

Epidermal pH is an indication of the skin's physiological condition. For example, pH of wound can be correlated to angiogenesis, protease activity, bacterial infection, etc. Chronic nonhealing wounds are known to have an elevated alkaline environment, while healing process occurs more readily in an acidic environment. Thus, dermal patches capable of continuous pH measurement can be used as point-of-care systems for monitoring skin disorder and the wound healing process. Here, pH-responsive hydrogel fibers are presented that can be used for long-term monitoring of epidermal wound condition. pH-responsive dyes are loaded into mesoporous microparticles and incorporated into hydrogel fibers using a microfluidic spinning system. The fabricated pH-responsive microfibers are flexible and can create conformal contact with skin. The response of pH-sensitive fibers with different compositions and thicknesses are characterized. The suggested technique is scalable and can be used to fabricate hydrogel-based wound dressings with clinically relevant dimensions. Images of the pH-sensing fibers during real-time pH measurement can be captured with a smart phone camera for convenient readout on-site. Through image processing, a quantitative pH map of the hydrogel fibers and the underlying tissue can be extracted. The developed skin dressing can act as a point-of-care device for monitoring the wound healing process. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

On-line detection of Escherichia coli intrusion in a pilot-scale drinking water distribution system.

PubMed

Ikonen, Jenni; Pitkänen, Tarja; Kosse, Pascal; Ciszek, Robert; Kolehmainen, Mikko; Miettinen, Ilkka T

2017-08-01

Improvements in microbial drinking water quality monitoring are needed for the better control of drinking water distribution systems and for public health protection. Conventional water quality monitoring programmes are not always able to detect a microbial contamination of drinking water. In the drinking water production chain, in addition to the vulnerability of source waters, the distribution networks are prone to contamination. In this study, a pilot-scale drinking-water distribution network with an on-line monitoring system was utilized for detecting bacterial intrusion. During the experimental Escherichia coli intrusions, the contaminant was measured by applying a set of on-line sensors for electric conductivity (EC), pH, temperature (T), turbidity, UV-absorbance at 254 nm (UVAS SC) and with a device for particle counting. Monitored parameters were compared with the measured E. coli counts using the integral calculations of the detected peaks. EC measurement gave the strongest signal compared with the measured baseline during the E. coli intrusion. Integral calculations showed that the peaks in the EC, pH, T, turbidity and UVAS SC data were detected corresponding to the time predicted. However, the pH and temperature peaks detected were barely above the measured baseline and could easily be mixed with the background noise. The results indicate that on-line monitoring can be utilized for the rapid detection of microbial contaminants in the drinking water distribution system although the peak interpretation has to be performed carefully to avoid being mixed up with normal variations in the measurement data. Copyright © 2017 Elsevier Ltd. All rights reserved.

A synthetic multifunctional mammalian pH sensor and CO2 transgene-control device.

PubMed

Ausländer, David; Ausländer, Simon; Charpin-El Hamri, Ghislaine; Sedlmayer, Ferdinand; Müller, Marius; Frey, Olivier; Hierlemann, Andreas; Stelling, Jörg; Fussenegger, Martin

2014-08-07

All metabolic activities operate within a narrow pH range that is controlled by the CO2-bicarbonate buffering system. We hypothesized that pH could serve as surrogate signal to monitor and respond to the physiological state. By functionally rewiring the human proton-activated cell-surface receptor TDAG8 to chimeric promoters, we created a synthetic signaling cascade that precisely monitors extracellular pH within the physiological range. The synthetic pH sensor could be adjusted by organic acids as well as gaseous CO2 that shifts the CO2-bicarbonate balance toward hydrogen ions. This enabled the design of gas-programmable logic gates, provided remote control of cellular behavior inside microfluidic devices, and allowed for CO2-triggered production of biopharmaceuticals in standard bioreactors. When implanting cells containing the synthetic pH sensor linked to production of insulin into type 1 diabetic mice developing diabetic ketoacidosis, the prosthetic network automatically scored acidic pH and coordinated an insulin expression response that corrected ketoacidosis. Copyright © 2014 Elsevier Inc. All rights reserved.

40 CFR Table 24 to Subpart Uuu of... - Continuous Monitoring Systems for Inorganic HAP Emissions From Catalytic Reforming Units

Code of Federal Regulations, 2012 CFR

2012-07-01

... scrubbing liquid) flow rate entering the scrubber during coke burn-off and catalyst rejuvenation; and... during coke burn-off and catalyst rejuvenation 1; and continuous parameter monitoring system to measure and record the pH or alkalinity of the water (or scrubbing liquid) exiting the scrubber during coke...

40 CFR Table 24 to Subpart Uuu of... - Continuous Monitoring Systems for Inorganic HAP Emissions From Catalytic Reforming Units

Code of Federal Regulations, 2014 CFR

2014-07-01

... scrubbing liquid) flow rate entering the scrubber during coke burn-off and catalyst rejuvenation; and... during coke burn-off and catalyst rejuvenation 1; and continuous parameter monitoring system to measure and record the pH or alkalinity of the water (or scrubbing liquid) exiting the scrubber during coke...

40 CFR Table 24 to Subpart Uuu of... - Continuous Monitoring Systems for Inorganic HAP Emissions From Catalytic Reforming Units

Code of Federal Regulations, 2013 CFR

2013-07-01

... scrubbing liquid) flow rate entering the scrubber during coke burn-off and catalyst rejuvenation; and... during coke burn-off and catalyst rejuvenation 1; and continuous parameter monitoring system to measure and record the pH or alkalinity of the water (or scrubbing liquid) exiting the scrubber during coke...

Kinetic buffers.

PubMed

Alibrandi, Giuseppe; Fabbrizzi, Luigi; Licchelli, Maurizio; Puglisi, Antonio

2015-01-12

This paper proposes a new type of molecular device that is able to act as an inverse proton sponge to slowly decrease the pH inside a reaction vessel. This makes the automatic monitoring of the concentration of pH-sensitive systems possible. The device is a composite formed of an alkyl chloride, which kinetically produces acidity, and a buffer that thermodynamically modulates the variation in pH value. Profiles of pH versus time (pH-t plots) have been generated under various experimental conditions by computer simulation, and the device has been tested by carrying out automatic spectrophotometric titrations, without using an autoburette. To underline the wide variety of possible applications, this new system has been used to realize and monitor HCl uptake by a di-copper(II) bistren complex in a single run, in a completely automatic experiment. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ubiquinone modified printed carbon electrodes for cell culture pH monitoring.

PubMed

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.

ITCS Test Strip Development and Certification

NASA Technical Reports Server (NTRS)

Carrigan, Caitlin; Adam, Niklas; Pickering, Karen; Gazda, Daniel; Piowaty, Hailey

2011-01-01

Internal coolant loops used for International Space Station thermal control must be periodically monitored for system health, including pH, biocide levels and any indication of ammonia. The presence of ammonia, possible via a microleak in the interface between the internal and external thermal control systems, could be a danger to the crew. The Internal Thermal Control System (ITCS) Sampling Kit uses test strips as a colorimetric indicator of pH and concentrations of biocide and free ammonia. This paper describes the challenges in designing an ammonia colorimetric indicator in a variable pH environment, as well as lessons learned, ultimately resulting in a robust test strip to indicate a hazardous ammonia leak.

Replaceable Sensor System for Bioreactor Monitoring

NASA Technical Reports Server (NTRS)

Mayo, Mike; Savoy, Steve; Bruno, John

2006-01-01

A sensor system was proposed that would monitor spaceflight bioreactor parameters. Not only will this technology be invaluable in the space program for which it was developed, it will find applications in medical science and industrial laboratories as well. Using frequency-domain-based fluorescence lifetime technology, the sensor system will be able to detect changes in fluorescence lifetime quenching that results from displacement of fluorophorelabeled receptors bound to target ligands. This device will be used to monitor and regulate bioreactor parameters including glucose, pH, oxygen pressure (pO2), and carbon dioxide pressure (pCO2). Moreover, these biosensor fluorophore receptor-quenching complexes can be designed to further detect and monitor for potential biohazards, bioproducts, or bioimpurities. Biosensors used to detect biological fluid constituents have already been developed that employ a number of strategies, including invasive microelectrodes (e.g., dark electrodes), optical techniques including fluorescence, and membrane permeable systems based on osmotic pressure. Yet the longevity of any of these sensors does not meet the demands of extended use in spacecraft habitat or bioreactor monitoring. It was therefore necessary to develop a sensor platform that could determine not only fluid variables such as glucose concentration, pO2, pCO2, and pH but can also regulate these fluid variables with controlled feedback loop.

Capsule Design for Blue Light Therapy against Helicobacter pylori.

PubMed

Li, Zhangyong; Ren, Binbin; Tan, Haiyan; Liu, Shengrong; Wang, Wei; Pang, Yu; Lin, Jinzhao; Zeng, Chen

2016-01-01

A photo-medical capsule that emits blue light for Helicobacter pylori treatment was described in this paper. The system consists of modules for pH sensing and measuring, light-emitting diode driver circuit, radio communication and microcontroller, and power management. The system can differentiate locations by monitoring the pH values of the gastrointestinal tract, and turn on and off the blue light according to the preset range of pH values. Our experimental tests show that the capsule can operate in the effective light therapy mode for more than 32 minutes and the wireless communication module can reliably transmit the measured pH value to a receiver located outside the body.

Technical note: A comparison of reticular and ruminal pH monitored continuously with 2 measurement systems at different weeks of early lactation.

PubMed

Falk, M; Münger, A; Dohme-Meier, F

2016-03-01

Subacute ruminal acidosis is one of the most important digestive disorders in high-yielding dairy cows fed highly fermentable diets. Monitoring of forestomach pH has been suggested as a potentially valuable tool for diagnosing subacute ruminal acidosis. The objective of the present study was to compare continuously recorded measurements of an indwelling telemetric pH sensor inserted orally in the reticulum with those obtained from a measurement system placed in the ventral sac of the rumen through a cannula. The experiment was conducted with 6 ruminally cannulated Holstein cows kept in a freestall barn. Equal numbers of cows were assigned to 2 treatment groups based on their previous lactation milk yield. Cows in treatment CON- were offered a diet consisting of only fresh herbage cut once daily, and cows in treatment CON+ got fresh herbage plus a concentrate supplement according to the individual milk yield of each cow to meet their predicted nutrient requirements. The experiment lasted from 2 wk before the predicted calving date until wk 8 of lactation. During the whole experiment, a pH value was recorded every 10 min in the reticulum using a wireless telemetry bolus including a pH sensor (eBolus, eCow Ltd., Exeter, Devon, UK), which had been applied orally using a balling gun. Simultaneously, in wk 2, before the estimated calving date and in wk 2, 4, 6, and 8 of lactation, the ruminal pH was measured every 30 s for 48 h with the LRCpH measurement system (Dascor Inc., Escondido, CA) placed in the ventral sac of the rumen through the cannula. The readings of the LRCpH measurement system were summarized as an average over 10 min for statistical analysis. The recorded pH values were on average 0.24 pH units higher in the reticulum than in the rumen. The reticular pH also showed less fluctuation (overall SD 0.19 pH units) than pH profiles recorded in the rumen (overall SD 0.51 pH units). Regardless of measurement system, pH was not influenced by treatment, but varied across week of lactation and decreased with advancing lactation. The difference between ruminal and reticular pH varied across week of lactation. Due to this variation, no fixed conversion factor can be provided to make pH measurements in the reticulum comparable with those in the rumen. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Implementation of PLUTO Buoy for Monitoring Water Quality in Indonesia, Reflection and Future Plans

NASA Astrophysics Data System (ADS)

Chandra, H.; Krismono, K.; Kusumaningrum, P. D.; Sianturi, D.; Firdaus, Y.; Taukhid, I.; Borneo, B. B.

2016-02-01

Research and development of PLUTO (Perairan Selalu Termonitor/Waters Always Monitored) buoy has reached its fourth year in 2015. Try out has been done in coastal waters, fishponds, fishing port ponds, and reservoirs. In the first year (2010) try out has been performed on coastal waters with off line measurement system. The buoy used temperature, salinity, DO and pH sensors. In the second year (2013) try out was carried out on fishponds and fishing port ponds using telemetry measurement system. In the third year (2014) try out was carried out on water reservoir with telemetry measurement system. In the fourth year (2015) android application is developed to monitor 4 water reservoirs and 1 lake. Beside that, observation point is added to 3 point depth for one buoy. Parameters used are temperature, DO, and turbidity. Three PLUTO buoys are placed in each reservoir, at inlet, outlet, and at center of fish cultivation. Through Ocean Science Meeting in New Orleans it is hoped that there will be input and suggestion from the experts for future development of the monitoring system for public inland waters (especially reservoir and lake) in Indonesia. Keywords: buoy PLUTO, salinity, temperature, Dissolved Oxygen (DO), pH, turbidity, telemetry

Lack of correlation between extended pH monitoring and scintigraphy in the evaluation of infants with gastroesophageal reflux

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tolia, V.; Calhoun, J.A.; Kuhns, L.R.

1990-05-01

Sixty-nine infants younger than 1 year of age, with symptoms of persistent vomiting, recurrent choking, apnea, persistent cough, or stridor, were evaluated for gastroesophageal reflux. All infants underwent extended intraesophageal pH monitoring for 16 to 24 hours as well as gastroesophageal scintigraphy with technetium 99m sulfur colloid to study the correlation between the two tests. Forty-eight infants exhibited reflux with extended pH monitoring whereas 46 infants showed reflux with scintigraphy. However, the diagnosis of reflux in individual patients by extended pH monitoring corresponded poorly with the diagnosis of reflux in the same patients by scintigraphy. Similarly, no correlation was observedmore » between extended pH monitoring and scintigraphy results, whether expressed as percent gastric emptying or as gastroesophageal reflux ratio. We conclude that extended pH monitoring and scintigraphy measure different pathophysiologic phenomena and detect reflux under different conditions. The ability of these tests to detect reflux may be complementary and they may be of greatest value when used together to enhance the sensitivity and specificity of the diagnostic evaluation. Extended pH monitoring and scintigraphy should not be used interchangeably to monitor gastroesophageal reflux.« less

Computer model of hydroponics nutrient solution pH control using ammonium.

PubMed

Pitts, M; Stutte, G

1999-01-01

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

In Vivo Model to Test Implanted Biosensors for Blood pH

NASA Technical Reports Server (NTRS)

Arnaud, Sara B.; Somps, Chris J.; Madou, Marc; Hines, John; Wade, Charles E. (Technical Monitor)

1997-01-01

Biosensors for monitoring physiologic data continuously through telemetry are available for heart rate, respiration, and temperature but not for blood pH or ions affected by hydrogen ion concentration. A telemetric biosensor for monitoring blood pH on-line could be used to identify and manage problems in fluid and electrolyte metabolism, cardiac and respiratory function during space flight and the acid-base status of patients without the need for venipuncture in patients on Earth. Critical to the development of biosensors is a method for evaluating their performance after implantation. Mature rats, prepared with jugular, cannulas for repeated blood samples, were exposed to a gas mixture containing high levels of carbon dioxide (7%) in a closed environment to induce mild respiratory acidosis. Serial blood gas and pH measurements in venous blood were compared with electrical responses from sensors implanted in the subcutaneous tissue. Animals became slightly tachypneic after exposure to excess CO2, but remained alert and active. After 5 minutes, basal blood pH decreased from 7.404 +/- 0.013 to 7.289 +/- 0.010 (p less than 0.001)and PC02 increased from 45 +/- 6 to 65 +/- 4 mm. Hg (p les than 0.001). Thereafter pH and blood gas parameters remained stable. Implanted sensors showed a decrease in millivolts (mV) which paralleled the change in pH and averaged 5-6 mV per 0.1 unit pH. Implanted sensors remained sensitive to modest changes in tissue pH for one week. A system for inducing acidosis in rats was developed to test the in vivo performance of pH biosensors. The system provides a method which is sensitive, rapid and reproducible in the same and different animals with full recovery, for testing the performance of sensors implanted in subcutaneous tissues.

Monitoring the Productivity of Coastal Systems Using PH ...

EPA Pesticide Factsheets

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.

Timely confirmation of gastro-esophageal reflux disease via pH monitoring: estimating budget impact on managed care organizations.

PubMed

Lee, W C; Yeh, Y C; Lacy, B E; Pandolfino, J E; Brill, J V; Weinstein, M L; Carlson, A M; Williams, M J; Wittek, M R; Pashos, C L

2008-05-01

Current guidelines recommend the use of pH monitoring to confirm the diagnosis of acid reflux in patients with a normal endoscopy. This analysis evaluated the financial impact of pH monitoring with the wireless pH capsule on a managed care organization (MCO) in the United States. A decision model was constructed to project total 1-year costs to manage GERD symptoms with and without the adoption of wireless pH capsules in a hypothetical MCO with 10 000 eligible adult enrollees, of whom 600 presented with GERD-like symptoms. Costs of GERD diagnosis, treatment, and symptom management for those in whom a GERD diagnosis was ruled out by pH monitoring were assessed. The incremental per-member-per-month (PMPM) and per-treated-member-per-month (PTMPM) costs were the primary outcomes. Data sources included literature, expert input, and standardized fee schedules. An increase of 10 percentage points in the use of pH monitoring with wireless pH capsules yielded incremental PMPM and PTMPM costs of $0.029 and $0.481, respectively. The costs of proton pump inhibitor (PPI) therapy to the plan dropped to $236,363 from $238,086, while increases were observed in pH monitoring (from $16 739 to $21 973) and non-GERD therapy costs (from $1392 to $1740). The results were sensitive to the percentage of patients requiring repeat endoscopy before wireless pH monitoring and the cost of PPIs. Timely and increased use of pH monitoring as recommended in published guidelines leads to less unnecessary use of PPIs with a modest budgetary impact on health plans.

Real-time pH monitoring of industrially relevant enzymatic reactions in a microfluidic side-entry reactor (μSER) shows potential for pH control.

PubMed

Gruber, Pia; Marques, Marco P C; Sulzer, Philipp; Wohlgemuth, Roland; Mayr, Torsten; Baganz, Frank; Szita, Nicolas

2017-06-01

Monitoring and control of pH is essential for the control of reaction conditions and reaction progress for any biocatalytic or biotechnological process. Microfluidic enzymatic reactors are increasingly proposed for process development, however typically lack instrumentation, such as pH monitoring. We present a microfluidic side-entry reactor (μSER) and demonstrate for the first time real-time pH monitoring of the progression of an enzymatic reaction in a microfluidic reactor as a first step towards achieving pH control. Two different types of optical pH sensors were integrated at several positions in the reactor channel which enabled pH monitoring between pH 3.5 and pH 8.5, thus a broader range than typically reported. The sensors withstood the thermal bonding temperatures typical of microfluidic device fabrication. Additionally, fluidic inputs along the reaction channel were implemented to adjust the pH of the reaction. Time-course profiles of pH were recorded for a transketolase and a penicillin G acylase catalyzed reaction. Without pH adjustment, the former showed a pH increase of 1 pH unit and the latter a pH decrease of about 2.5 pH units. With pH adjustment, the pH drop of the penicillin G acylase catalyzed reaction was significantly attenuated, the reaction condition kept at a pH suitable for the operation of the enzyme, and the product yield increased. This contribution represents a further step towards fully instrumented and controlled microfluidic reactors for biocatalytic process development. © 2017 The Authors. Biotechnology Journal published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

RTEMIS: Real-time Tumoroid and Environment Monitoring Using Impedance Spectroscopy and pH Sensing

NASA Astrophysics Data System (ADS)

Alexander, Frank A., Jr.

This research utilizes Electrical Impedance Spectroscopy, a technique classically used for electrochemical analysis and material characterization, as the basis for a non-destructive, label-free assay platform for three dimensional (3D) cellular spheroids. In this work, a linear array of microelectrodes is optimized to rapidly respond to changes located within a 3D multicellular model. In addition, this technique is coupled with an on chip micro-pH sensor for monitoring the environment around the cells. Finally, the responses of both impedance and pH are correlated with physical changes within the cellular model. The impedance analysis system realized through this work provides a foundation for the development of high-throughput drug screening systems that utilize multiple parallel sensing modalities including pH and impedance sensing in order to quickly assess the efficacy of specific drug candidates. The slow development of new drugs is mainly attributed to poor predictability of current chemosensitivity and resistivity assays, as well as genetic differences between the animal models used for tests and humans. In addition, monolayer cultures used in early experimentation are fundamentally different from the complex structure of organs in vivo. This requires the study of smaller 3D models (spheroids) that more efficiently replicate the conditions within the body. The main objective of this research was to develop a microfluidic system on a chip that is capable of deducing viability and morphology of 3D tumor spheroids by monitoring both the impedance of the cellular model and the pH of their local environment. This would provide a fast and reliable method for screening pharmaceutical compounds in a high-throughput system.

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?

PubMed

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 predominantly normal in patients with non-acid reflux, ineffective esophageal motility is often monitored in patients with acid reflux. In the literature, there are contradictory and an insufficient number of studies regarding radiological methods for the diagnosis of GERD. There are inconsistent values for sensitivity and specificity among the barium studies. There are inadequate studies in the literature involving scintigraphic examinations in the diagnosis of GERD, and a majority of existing studies have been conducted in the pediatric group. The results of a few studies do not provide sufficient contribution toward the implementation in clinical practice.

Influence of microbial growth in the redox potential of fermented cucumbers

USDA-ARS?s Scientific Manuscript database

Commonly, pH measurements are used during the production of fermented cucumbers to indirectly monitor growth of lactic acid bacteria (LAB) and acid production. Redox potential (Eh) measurements, which are determined by the flux of electrons in a system, could serve as a more accurate tool to monitor...

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

NASA Astrophysics Data System (ADS)

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.

Magnetic resonance imaging (MRI) and relaxation spectrum analysis as methods to investigate swelling in whey protein gels.

PubMed

Oztop, Mecit H; Rosenberg, Moshe; Rosenberg, Yael; McCarthy, Kathryn L; McCarthy, Michael J

2010-10-01

Effective means for controlled delivery of nutrients and nutraceuticals are needed. Whey protein-based gels, as a model system and as a potential delivery system, exhibit pH-dependent swelling when placed in aqueous solutions. Understanding the physics that govern gel swelling is thus important when designing gel-based delivery platforms. The extent of swelling over time was monitored gravimetrically. In addition to gravimetric measurements, magnetic resonance imaging (MRI) a real-time noninvasive imaging technique that quantified changes in geometry and water content of these gels was utilized. Heat-set whey protein gels were prepared at pH 7 and swelling was monitored in aqueous solutions with pH values of 2.5, 7, and 10. Changes in dimension over time, as characterized by the number of voxels in an image, were correlated to gravimetric measurements. Excellent correlations between mass uptake and volume change (R(2)= 0.99) were obtained for the gels in aqueous solutions at pH 7 and 10, but not for gels in the aqueous solution at pH 2.5. To provide insight into the mechanisms for water uptake, nuclear magnetic resonance (NMR) relaxation times were measured in independent experiments. The relaxation spectrum for the spin-spin relaxation time (T(2)) showed the presence of 3 proton pools for pH 7 and 10 trials and 4 proton pools for pH 2.5 trials. Results demonstrate that MRI and NMR relaxation measurements provided information about swelling in whey protein gels that can constitute a new means for investigating and developing effective delivery systems for foods.

The combination of pH monitoring in the most distal esophagus and symptom association analysis markedly improves the clinical value of esophageal pH tests.

PubMed

Hall, Mats Guerrero Garcia; Wenner, Jörgen; Öberg, Stefan

2016-01-01

The poor sensitivity of esophageal pH monitoring substantially limits the clinical value of the test. The aim of this study was to compare the diagnostic accuracy of esophageal pH monitoring and symptom association analysis performed at the conventional level with that obtained in the most distal esophagus. Eighty-two patients with typical reflux symptoms and 49 asymptomatic subjects underwent dual 48-h pH monitoring with the electrodes positioned immediately above, and 6 cm above the squamo-columnar junction (SCJ). The degree of esophageal acid exposure and the temporal relationship between reflux events and symptoms were evaluated. The sensitivity of pH recording and the diagnostic yield of Symptom Association Probability (SAP) were significantly higher for pH monitoring performed at the distal compared with the conventional level (82% versus 65%, p<0.001 and 74% versus 62%, p<0.001, respectively). The greatest improvement was observed in patients with non-erosive disease. In this group, the sensitivity increased from 46% at the standard level to 66% immediately above the SCJ, and with the combination of a positive SAP as a marker for a positive pH test, the diagnostic yield further increased to 94%. The diagnostic accuracy of esophageal pH monitoring in the most distal esophagus is superior to that performed at the conventional level and it is further improved with the combination of symptom association analysis. PH monitoring with the pH electrode positioned immediately above the SCJ should be introduced in clinical practice and always combined with symptom association analysis.

pH Optrode Instrumentation

NASA Technical Reports Server (NTRS)

Tabacco, Mary Beth; Zhou, Quan

1995-01-01

pH-sensitive chromophoric reagents immobilized in porous optical fibers. Optoelectronic instrumentation system measures acidity or alkalinity of aqueous nutrient solution. Includes one or more optrodes, which are optical-fiber chemical sensors, in sense, analogous to electrodes but not subject to some of spurious effects distorting readings taken by pH electrodes. Concept of optrodes also described in "Ethylene-Vapor Optrodes" (KSC-11579). pH optrode sensor head, with lead-in and lead-out optical fibers, convenient for monitoring solutions located away from supporting electronic equipment.

pH dynamics in sewers and its modeling.

PubMed

Sharma, Keshab; Ganigue, Ramon; Yuan, Zhiguo

2013-10-15

pH variation in sewers has a significant effect on hydrogen sulfide production and emissions, and hence its accurate prediction is critical for the optimization of mitigation strategies. In this study, the nature and dynamics of pH variation in a sewer system is examined. Three sewer systems collecting domestic wastewater were monitored, with pH in all cases showing large diurnal variations. pH in fresh sewage in all three cases had a very similar trend with maximum pH in the range of 8.5-8.7. pH variation in fresh sewage followed the same pattern as the sewage flow rate, suggesting that sewage pH is influenced by household water use. Nitrogen content of the wastewater was found to be the most influential factor causing pH variation in fresh sewage, with the total ammonium concentration variation well correlated with the pH variation. A methodology for predicting pH variation in sewers is developed and calibration protocols proposed. The methodology, which is based on the concept of charge balance, was validated using titration curves and field pH data. Measurement of the total ammonium concentration in fresh sewage was found necessary and adequate for the calibration of the charge balance-based pH model. Copyright © 2013 Elsevier Ltd. All rights reserved.

24-h multichannel intraluminal impedance-pH monitoring may be an inadequate test for detecting gastroesophageal reflux in patients with mixed typical and atypical symptoms.

PubMed

Han, Michelle S; Lada, Michal J; Nieman, Dylan R; Tschoner, Andreas; Peyre, Christian G; Jones, Carolyn E; Watson, Thomas J; Peters, Jeffrey H

2015-07-01

The detection of gastroesophageal reflux (GERD) via pH testing is the key component of the evaluation of patients considered for antireflux surgery. Two common pH testing systems exist, a multichannel, intraluminal impedance-pH monitoring (MII-pH) catheter, and wireless (Bravo(®)) capsule; however, discrepancies between the two systems exist. In patients with atypical symptoms, MII-pH catheter is often used preferentially. We aimed to elucidate the magnitude of this discrepancy and to assess the diagnostic value of MII-pH and the Bravo wireless capsule in a population of patients with mixed respiratory and typical symptoms. The study population consisted of 66 patients tested with MII-pH and Bravo pH testing within 90 days between July 2009 and 2013. All patients presented with laryngo-pharyngo-respiratory (LPR) symptoms. Patient demographics, symptomatology, manometric and endoscopic findings, and pH monitoring parameters were analyzed. Patients were divided into four comparison groups: both pH tests positive, MII-pH negative/Bravo positive, MII-pH positive/Bravo negative, and both pH tests negative. Nearly half of the patients (44%) had discordant pH test results. Of these, 90% (26/29) had a negative MII-pH but positive Bravo study. In this group, the difference in the DeMeester score was large, a median of 29.3. These patients had a higher BMI (28.5 vs. 26.1, p = 0.0357), were more likely to complain of heartburn (50 vs. 23%, p = 0.0110), to have a hiatal hernia, (85 vs. 53%, p = 0.0075) and a structurally defective lower esophageal sphincter (LES, 85 vs. 58%, p = 0.0208). In patients with LPR symptoms, we found a high prevalence of discordant esophageal pH results, most commonly a negative MII-pH catheter and positive Bravo. As these patients exhibited characteristics consistent with GERD (heartburn, defective LES, hiatal hernia), the Bravo results are likely true. A 24-h MII-pH catheter study may be inadequate to diagnose GERD in this patient population.

Portable system for temperature monitoring in all phases of wine production.

PubMed

Boquete, Luciano; Cambralla, Rafael; Rodríguez-Ascariz, J M; Miguel-Jiménez, J M; Cantos-Frontela, J J; Dongil, J

2010-07-01

This paper presents a low-cost and highly versatile temperature-monitoring system applicable to all phases of wine production, from grape cultivation through to delivery of bottled wine to the end customer. Monitoring is performed by a purpose-built electronic system comprising a digital memory that stores temperature data and a ZigBee communication system that transmits it to a Control Centre for processing and display. The system has been tested under laboratory conditions and in real-world operational applications. One of the system's advantages is that it can be applied to every phase of wine production. Moreover, with minimum modification, other variables of interest (pH, humidity, etc.) could also be monitored and the system could be applied to other similar sectors, such as olive-oil production. 2010 ISA. Published by Elsevier Ltd. All rights reserved.

21 CFR 862.1550 - Urinary pH (nonquantitative) test system.

Code of Federal Regulations, 2010 CFR

2010-04-01

... (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test... the monitoring of patients with certain diets. (b) Classification. Class I (general controls). The...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Casella, Amanda J.; Hylden, Laura R.; Campbell, Emily L.

Knowledge of real-time solution properties and composition is a necessity for any spent nuclear fuel reprocessing method. Metal-ligand speciation in aqueous solutions derived from the dissolved commercial spent fuel is highly dependent upon the acid concentration/pH, which influences extraction efficiency and the resulting speciation in the organic phase. Spectroscopic process monitoring capabilities, incorporated in a counter current centrifugal contactor bank, provide a pathway for on-line real-time measurement of solution pH. The spectroscopic techniques are process-friendly and can be easily configured for on-line applications, while classic potentiometric pH measurements require frequent calibration/maintenance and have poor long-term stability in aggressive chemical andmore » radiation environments. Our research is focused on developing a general method for on-line determination of pH of aqueous solutions through chemometric analysis of Raman spectra. Interpretive quantitative models have been developed and validated under the range of chemical composition and pH using a lactic acid/lactate buffer system. The developed model was applied to spectra obtained on-line during solvent extractions performed in a centrifugal contactor bank. The model predicted the pH within 11% for pH > 2, thus demonstrating that this technique could provide the capability of monitoring pH on-line in applications such as nuclear fuel reprocessing.« less

Fluorescent ratiometric pH indicator SypHer2: applications in neuroscience and regenerative biology

PubMed Central

Matlashov, Mikhail E.; Bogdanova, Yulia A.; Ermakova, Galina V.; Mishina, Natalia M.; Ermakova, Yulia G.; Nikitin, Evgeny S.; Balaban, Pavel M.; Okabe, Shigeo; Lukyanov, Sergey; Enikolopov, Grigori; Zaraisky, Andrey G.; Belousov, Vsevolod V.

2015-01-01

Background SypHer is a genetically encoded fluorescent pH-indicator with a ratiometric readout, suitable for measuring fast intracellular pH shifts. However, a relatively low brightness of the indicator limits its use. Methods Here we designed a new version of pH-sensor - SypHer-2, that has up to three times brighter fluorescence signal in cultured mammalian cells compared to the SypHer. Results Using the new indicator we registered activity-associated pH oscillations in neuronal cell culture. We observed prominent temporal neuronal cytoplasm acidification that occurs in parallel with calcium entry. Furthermore, we monitored pH in presynaptic and postsynaptic termini by targeting SypHer-2 directly to these compartments and revealed marked differences in pH dynamics between synaptic boutons and dendritic spines. Finally, we were able to reveal for the first time the intracellular pH drop which occurs within an extended region of the amputated tail of the Xenopus laevis tadpole before it begins to regenerate. Conclusions SypHer2 is suitable for quantitative monitoring of pH in biological systems of different scales, from small cellular subcompartments to animal tissues in vivo. General significance The new pH-sensor will help to investigate pH-dependent processes in both in vitro and in vivo studies. PMID:26259819

Fluorescent ratiometric pH indicator SypHer2: Applications in neuroscience and regenerative biology.

PubMed

Matlashov, Mikhail E; Bogdanova, Yulia A; Ermakova, Galina V; Mishina, Natalia M; Ermakova, Yulia G; Nikitin, Evgeny S; Balaban, Pavel M; Okabe, Shigeo; Lukyanov, Sergey; Enikolopov, Grigori; Zaraisky, Andrey G; Belousov, Vsevolod V

2015-11-01

SypHer is a genetically encoded fluorescent pH-indicator with a ratiometric readout, suitable for measuring fast intracellular pH shifts. However, the relatively low brightness of the indicator limits its use. Here we designed a new version of pH-sensor called SypHer-2, which has up to three times brighter fluorescence in cultured mammalian cells compared to the SypHer. Using the new indicator we registered activity-associated pH oscillations in neuronal cell culture. We observed prominent transient neuronal cytoplasm acidification that occurs in parallel with calcium entry. Furthermore, we monitored pH in presynaptic and postsynaptic termini by targeting SypHer-2 directly to these compartments and revealed marked differences in pH dynamics between synaptic boutons and dendritic spines. Finally, we were able to reveal for the first time the intracellular pH drop that occurs within an extended region of the amputated tail of the Xenopus laevis tadpole before it begins to regenerate. SypHer2 is suitable for quantitative monitoring of pH in biological systems of different scales, from small cellular subcompartments to animal tissues in vivo. The new pH-sensor will help to investigate pH-dependent processes in both in vitro and in vivo studies. Copyright © 2015 Elsevier B.V. All rights reserved.

An implantable, batteryless, and wireless capsule with integrated impedance and pH sensors for gastroesophageal reflux monitoring.

PubMed

Cao, Hung; Landge, Vaibhav; Tata, Uday; Seo, Young-Sik; Rao, Smitha; Tang, Shou-Jiang; Tibbals, H F; Spechler, Stuart; Chiao, J-C

2012-11-01

In this study, a device for gastroesophageal reflux disease (GERD) monitoring has been prototyped. The system consists of an implantable, batteryless and wireless transponder with integrated impedance and pH sensors; and a wearable, external reader that wirelessly powers up the transponder and interprets the transponded radio-frequency signals. The transponder implant with the total size of 0.4 cm × 0.8 cm × 3.8 cm harvests radio frequency energy to operate dual-sensor and load-modulation circuitry. The external reader can store the data in a memory card and/or send it to a base station wirelessly, which is optional in the case of multiple-patient monitoring in a hospital or conducting large-scale freely behaving animal experiments. Tests were carried out to verify the signal transduction reliability in different situations for antenna locations and orientation. In vitro, experiments were conducted in a mannequin model by positioning the sensor capsule inside the wall of a tube mimicking the esophagus. Different liquids with known pH values were flushed through the tube creating reflux episodes and wireless signals were recorded. Live pigs under anesthesia were used for the animal models with the transponder implant attached on the esophageal wall. The reflux episodes were created while the sensor data were recorded wirelessly. The data were compared with those recorded independently by a clinically used wireless pH sensor capsule placed next to our implant transponder. The results showed that our transponder detected every episode in both acid and nonacid nature, while the commercial pH sensor missed events that had similar, repeated pH values, and failed to detect pH values higher than 10. Our batteryless transponder does not require a battery thus allowing longer diagnosis and prognosis periods to monitor drug efficacy, as well as providing accurate assessment of GERD symptoms.

Evaluation of the 5 and 8 pH point titration methods for monitoring anaerobic digesters treating solid waste.

PubMed

Vannecke, T P W; Lampens, D R A; Ekama, G A; Volcke, E I P

2015-01-01

Simple titration methods certainly deserve consideration for on-site routine monitoring of volatile fatty acid (VFA) concentration and alkalinity during anaerobic digestion (AD), because of their simplicity, speed and cost-effectiveness. In this study, the 5 and 8 pH point titration methods for measuring the VFA concentration and carbonate system alkalinity (H2CO3*-alkalinity) were assessed and compared. For this purpose, synthetic solutions with known H2CO3*-alkalinity and VFA concentration as well as samples from anaerobic digesters treating three different kind of solid wastes were analysed. The results of these two related titration methods were verified with photometric and high-pressure liquid chromatography measurements. It was shown that photometric measurements lead to overestimations of the VFA concentration in the case of coloured samples. In contrast, the 5 pH point titration method provides an accurate estimation of the VFA concentration, clearly corresponding with the true value. Concerning the H2CO3*-alkalinity, the most accurate and precise estimations, showing very similar results for repeated measurements, were obtained using the 8 pH point titration. Overall, it was concluded that the 5 pH point titration method is the preferred method for the practical monitoring of AD of solid wastes due to its robustness, cost efficiency and user-friendliness.

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

PubMed

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 < 10 mm Hg; PCO2 > 60 mm Hg, and pH < 6.8. We have had no complications with this device; the risks are similar to those of placing a parenchymal intracranial pressure monitor. We believe that assessment of interstitial cerebral oxygen saturation can be of great value both intraoperatively and postoperatively. In our experience, the Paratrend 7 system is an effective method of measuring tissue cerebral oxygen tension, along with carbon dioxide levels, pH, and temperature.

Modified Organosilica Core-Shell Nanoparticles for Stable pH Sensing in Biological Solutions.

PubMed

Robinson, Kye J; Huynh, Gabriel T; Kouskousis, Betty P; Fletcher, Nicholas L; Houston, Zachary H; Thurecht, Kristofer J; Corrie, Simon R

2018-04-19

Continuous monitoring using nanoparticle-based sensors has been successfully employed in complex biological systems, yet the sensors still suffer from poor long-term stability partially because of the scaffold materials chosen to date. Organosilica core-shell nanoparticles containing a mixture of covalently incorporated pH-sensitive (shell) and pH-insensitive (core) fluorophores is presented as a continuous pH sensor for application in biological media. In contrast to previous studies focusing on similar materials, we sought to investigate the sensor characteristics (dynamic range, sensitivity, response time, stability) as a function of material properties. The ratio of the fluorescence intensities at specific wavelengths was found to be highly sensitive to pH over a physiologically relevant range (4.5-8) with a response time of <100 ms, significantly faster than that of previously reported response times using silica-based particles. Particles produced stable, pH-specific signals when stored at room temperature for more than 80 days. Finally, we demonstrated that the nanosensors successfully monitored the pH of a bacterial culture over 15 h and that pH changes in the skin of mouse cadavers could also be observed via in vivo fluorescence imaging following subcutaneous injection. The understanding gained from linking sensor characteristics and material properties will inform the next generation of optical nanosensors for continuous-monitoring applications.

Diurnal and seasonal variations of pH for a year in the western subarctic North Pacific observed by using a hybrid pH sensor

NASA Astrophysics Data System (ADS)

Nakano, Yoshiyuki; Fujiki, Tetsuichi; Kimoto, Katsunori; Miwa, Tetsuya

2017-04-01

Ocean acidification has many far reaching impacts on plankton community in the ocean. There is great need of quality instrumentation to assess and monitor the changing seawater pH. To meet the need, we have developed the in situ high accurate pH sensor (Hybrid pH sensor: HpHS) for the long-term seawater pH monitoring to participate the Wendy Schmidt Ocean health XPRIZE. 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. 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 is correcting the value of the potentiometric pH (measuring frequently) by the value of the spectrophotometric pH (measuring less frequently). It is possible to calibrate in situ with Tris buffer or CRM on the spectrophotometric pH sensor. Therefore, the drifts in the value of potentiometric pH measurements can be compensated using the pH value obtained from the spectrophotometric pH measurements. Thereby, the HpHS can measure accurately the value of pH over a long period of time with low power consumption. In order to understand the seasonal and inter-annual variabilities of biogeochemical cycles and ecosystems, ship-based studies have been carried out since 1997 at time-series station K2 (47oN, 160oE) in the subarctic western North Pacific, which is a region with progression of ocean acidification. However, the ship-based studies of the open ocean have been limited in their ability to conduct high-frequency observations for understanding the biogeochemical cycles and ecosystems. To overcome the problem, we developed a hybrid profiling buoy system. The HpHS was attached to a remote automatic water sampler (200m) in the buoy system in July 2015. We recovered the buoy system in June 2016 and succeeded in observing seawater pH every four hours for a year. Here, we show an overview of the diurnal and seasonal variations of pH for a year at station K2. In addition, we examine a relationship between the pH variations and marine calcifiers recovered by the sediment trap during the same period.

40 CFR 401.17 - pH Effluent limitations under continuous monitoring.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 30 2012-07-01 2012-07-01 false pH Effluent limitations under... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS GENERAL PROVISIONS § 401.17 pH Effluent limitations under continuous monitoring. (a) Where a permittee continuously measures the pH of wastewater pursuant to a...

40 CFR 401.17 - pH Effluent limitations under continuous monitoring.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 30 2013-07-01 2012-07-01 true pH Effluent limitations under... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS GENERAL PROVISIONS § 401.17 pH Effluent limitations under continuous monitoring. (a) Where a permittee continuously measures the pH of wastewater pursuant to a...

40 CFR 401.17 - pH Effluent limitations under continuous monitoring.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 29 2014-07-01 2012-07-01 true pH Effluent limitations under... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS GENERAL PROVISIONS § 401.17 pH Effluent limitations under continuous monitoring. (a) Where a permittee continuously measures the pH of wastewater pursuant to a...

40 CFR 401.17 - pH Effluent limitations under continuous monitoring.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 29 2011-07-01 2009-07-01 true pH Effluent limitations under... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS GENERAL PROVISIONS § 401.17 pH Effluent limitations under continuous monitoring. (a) Where a permittee continuously measures the pH of wastewater pursuant to a...

40 CFR 401.17 - pH Effluent limitations under continuous monitoring.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 28 2010-07-01 2010-07-01 true pH Effluent limitations under... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS GENERAL PROVISIONS § 401.17 pH Effluent limitations under continuous monitoring. (a) Where a permittee continuously measures the pH of wastewater pursuant to a...

Real-time monitoring of process parameters in rice wine fermentation by a portable spectral analytical system combined with multivariate analysis.

PubMed

Ouyang, Qin; Zhao, Jiewen; Pan, Wenxiu; Chen, Quansheng

2016-01-01

A portable and low-cost spectral analytical system was developed and used to monitor real-time process parameters, i.e. total sugar content (TSC), alcohol content (AC) and pH during rice wine fermentation. Various partial least square (PLS) algorithms were implemented to construct models. The performance of a model was evaluated by the correlation coefficient (Rp) and the root mean square error (RMSEP) in the prediction set. Among the models used, the synergy interval PLS (Si-PLS) was found to be superior. The optimal performance by the Si-PLS model for the TSC was Rp = 0.8694, RMSEP = 0.438; the AC was Rp = 0.8097, RMSEP = 0.617; and the pH was Rp = 0.9039, RMSEP = 0.0805. The stability and reliability of the system, as well as the optimal models, were verified using coefficients of variation, most of which were found to be less than 5%. The results suggest this portable system is a promising tool that could be used as an alternative method for rapid monitoring of process parameters during rice wine fermentation. Copyright © 2015 Elsevier Ltd. All rights reserved.

QSAR-like models: a potential tool for the selection of PhACs and EDCs for monitoring purposes in drinking water treatment systems--a review.

PubMed

Delgado, Luis F; Charles, Philippe; Glucina, Karl; Morlay, Catherine

2012-12-01

Recent studies have demonstrated the presence of trace-level pharmaceutically active compounds (PhACs) and endocrine disrupting compounds (EDCs) in a number of finished drinking waters (DWs). Since there is sparse knowledge currently available on the potential effects on human health associated with the chronic exposure to trace levels of these Emerging Contaminants (ECs) through routes such as DW, it is suggested that the most appropriate criterion is a treatment criterion in order to prioritize ECs to be monitored during DW preparation. Hence, only the few ECs showing the lowest removals towards a given DW Treatment (DWT) process would serve as indicators of the overall efficiency of this process and would be relevant for DW quality monitoring. In addition, models should be developed for estimating the removal of ECs in DWT processes, thereby overcoming the practical difficulties of experimentally assessing each compound. Therefore, the present review has two objectives: (1) to provide an overview of the recent scientific surveys on the occurrence of PhACs and EDCs in finished DWs; and (2) to propose the potential of Quantitative-Structure-Activity-Relationship-(QSAR)-like models to rank ECs found in environmental waters, including parent compounds, metabolites and transformation products, in order to select the most relevant compounds to be considered as indicators for monitoring purposes in DWT systems. Copyright © 2012 Elsevier Ltd. All rights reserved.

Final Report: Enabling Exascale Hardware and Software Design through Scalable System Virtualization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bridges, Patrick G.

2015-02-01

In this grant, we enhanced the Palacios virtual machine monitor to increase its scalability and suitability for addressing exascale system software design issues. This included a wide range of research on core Palacios features, large-scale system emulation, fault injection, perfomrance monitoring, and VMM extensibility. This research resulted in large number of high-impact publications in well-known venues, the support of a number of students, and the graduation of two Ph.D. students and one M.S. student. In addition, our enhanced version of the Palacios virtual machine monitor has been adopted as a core element of the Hobbes operating system under active DOE-fundedmore » research and development.« less

A real-time measurement system for parameters of live biology metabolism process with fiber optics

NASA Astrophysics Data System (ADS)

Tao, Wei; Zhao, Hui; Liu, Zemin; Cheng, Jinke; Cai, Rong

2010-08-01

Energy metabolism is one of the basic life activities of cellular in which lactate, O2 and CO2 will be released into the extracellular environment. By monitoring the quantity of these parameters, the mitochondrial performance will be got. A continuous measurement system for the concentration of O2, CO2 and PH value is introduced in this paper. The system is made up of several small-sized fiber optics biosensors corresponding to the container. The setup of the system and the principle of measurement of several parameters are explained. The setup of the fiber PH sensor based on principle of light absorption is also introduced in detail and some experimental results are given. From the results we can see that the system can measure the PH value precisely suitable for cell cultivation. The linear and repeatable accuracies are 3.6% and 6.7% respectively, which can fulfill the measurement task.

Bedside arterial blood gas monitoring system using fluorescent optical sensors

NASA Astrophysics Data System (ADS)

Bartnik, Daniel J.; Rymut, Russell A.

1995-05-01

We describe a bedside arterial blood gas (ABG) monitoring system which uses fluorescent optical sensors in the measurement of blood pH, PCO2 and PO2. The Point-of-Care Arterial Blood Gas Monitoring System consists of the SensiCathTM optical sensor unit manufactured by Optical Sensors Incorporated and the TramTM Critical Care Monitoring System with ABG Module manufactured by Marquette Electronics Incorporated. Current blood gas measurement techniques require a blood sample to be removed from the patient and transported to an electrochemical analyzer for analysis. The ABG system does not require removal of blood from the patient or transport of the sample. The sensor is added to the patient's existing arterial line. ABG measurements are made by drawing a small blood sample from the arterial line in sufficient quantity to ensure an undiluted sample at the sensor. Measurements of pH, PCO2 and PO2 are made within 60 seconds. The blood is then returned to the patient, the line flushed and results appear on the bedside monitor. The ABG system offers several advantages over traditional electrochemical analyzers. Since the arterial line remains closed during the blood sampling procedure the patient's risk of infection is reduced and the caregiver's exposure to blood is eliminated. The single-use, disposable sensor can be measure 100 blood samples over 72 hours after a single two-point calibration. Quality Assurance checks are also available and provide the caregiver the ability to assess system performance even after the sensor is patient attached. The ABG module integrates with an existing bedside monitoring system. This allows ABG results to appear on the same display as ECG, respiration, blood pressure, cardiac output, SpO2, and other clinical information. The small module takes up little space in the crowded intensive care unit. Performance studies compare the ABG system with an electrochemical blood gas analyzer. Study results demonstrated accurate and precise blood gas measurement of 100 samples and 72 hour performance without need for re-calibration.

A pH-based biosensor for detection of arsenic in drinking water.

PubMed

de Mora, K; Joshi, N; Balint, B L; Ward, F B; Elfick, A; French, C E

2011-05-01

Arsenic contaminated groundwater is estimated to affect over 100 million people worldwide, with Bangladesh and West Bengal being among the worst affected regions. A simple, cheap, accurate and disposable device is required for arsenic field testing. We have previously described a novel biosensor for arsenic in which the output is a change in pH, which can be detected visually as a colour change by the use of a pH indicator. Here, we present an improved formulation allowing sensitive and accurate detection of less than 10 ppb arsenate with static overnight incubation. Furthermore, we describe a cheap and simple high-throughput system for simultaneous monitoring of pH in multiple assays over time. Up to 50 samples can be monitored continuously over the desired time period. Cells can be stored and distributed in either air-dried or freeze-dried form. This system was successfully tested on arsenic-contaminated groundwater samples from the South East region of Hungary. We hope to continue to develop this sensor to produce a device suitable for field trials.

An iridium oxide microelectrode for monitoring acute local pH changes of endothelial cells.

PubMed

Ng, Shu Rui; O'Hare, Danny

2015-06-21

pH sensors were fabricated by anodically electrodepositing iridium oxide films (AEIROFs) onto microelectrodes on chips and coated with poly(ethyleneimine) (PEI) for mechanical stability. These demonstrate super-Nernstian response to pH from pH 4.0 to 7.7 in chloride-free phosphate buffer. The surface of the chip was coated with fibronectin for the attachment of porcine aortic endothelial cells (PAECs). The working capability of the pH sensor for monitoring acute local pH changes was investigated by stimulating the PAECs with thrombin. Our results show that thrombin induced acute extracellular acidification of PAECs and dissolution of fibronectin, causing the local pH to decrease. The use of PD98059, a mitogen-activated protein kinase (MAPK) inhibitor, reduced extracellular acidification and an increase in local pH was observed. This study shows that our pH sensors can facilitate the investigation of acute cellular responses to stimulation by monitoring the real-time, local pH changes of cells attached to the sensors.

Application of Aquaculture Monitoring System Based on CC2530

NASA Astrophysics Data System (ADS)

Chen, H. L.; Liu, X. Q.

In order to improve the intelligent level of aquaculture technology, this paper puts forward a remote wireless monitoring system based on ZigBee technology, GPRS technology and Android mobile phone platform. The system is composed of wireless sensor network (WSN), GPRS module, PC server, and Android client. The WSN was set up by CC2530 chips based on ZigBee protocol, to realize the collection of water quality parameters such as the water level, temperature, PH and dissolved oxygen. The GPRS module realizes remote communication between WSN and PC server. Android client communicates with server to monitor the level of water quality. The PID (proportion, integration, differentiation) control is adopted in the control part, the control commands from the android mobile phone is sent to the server, the server again send it to the lower machine to control the water level regulating valve and increasing oxygen pump. After practical testing to the system in Liyang, Jiangsu province, China, temperature measurement accuracy reaches 0.5°C, PH measurement accuracy reaches 0.3, water level control precision can be controlled within ± 3cm, dissolved oxygen control precision can be controlled within ±0.3 mg/L, all the indexes can meet the requirements, this system is very suitable for aquaculture.

DFT Study of PH3 Physisorption and Chemisorptions on Boron Nitride Nanotubes

NASA Astrophysics Data System (ADS)

Rakhshi, Mahdi; Mohsennia, Mohsen; Rasa, Hossein

2018-03-01

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

Monitoring of internal pH gradients within multi-layer tablets by optical methods and EPR imaging.

PubMed

Eisenächer, Friederike; Schädlich, Andreas; Mäder, Karsten

2011-09-30

The high variability of gastrointestinal pH is a general challenge regarding constant release from oral drug delivery systems, especially for ionisable drugs. These drugs often show a pH-dependent solubility and therewith associated intra- and inter-individual variability of emerging drug plasma levels. Several strategies have been investigated with the intention to influence the microenvironmental pH (pH(M)) within solid formulations and therefore achieve pH-independent release profiles. Because of the heterogeneity of solid systems, a precise prediction of the occurring pH(M) is rather difficult. It is therefore important to monitor the pH(M) within the formulations to achieve requested release as well as to minimise pH-dependent degradation processes of the active compound. The purpose of the current study was the analysis of pH(M) gradients within 2- and 3-layer tablets during hydration using 3 different techniques for comparison intensions, in particular a pH indicator dye, fluorescence imaging and EPR imaging. The influence of the presence or absence of pH modifying substances and of an additional lipophilic inter layer on the pH(M) was investigated as well as the variation of matrix forming excipient and buffer pH. The influence of the pH(M) on drug release was analysed as well. In addition, benchtop MRI was accomplished to gain a deeper insight on the hydration and erosion behaviour of 2- and 3-layer tablets. Copyright © 2010 Elsevier B.V. All rights reserved.

Water Sensors

NASA Technical Reports Server (NTRS)

1992-01-01

Mike Morris, former Associate Director of STAC, formed pHish Doctor, Inc. to develop and sell a pH monitor for home aquariums. The monitor, or pHish Doctor, consists of a sensor strip and color chart that continually measures pH levels in an aquarium. This is important because when the level gets too high, ammonia excreted by fish is highly toxic; at low pH, bacteria that normally break down waste products stop functioning. Sales have run into the tens of thousands of dollars. A NASA Tech Brief Technical Support Package later led to a salt water version of the system and a DoE Small Business Innovation Research (SBIR) grant for development of a sensor for sea buoys. The company, now known as Ocean Optics, Inc., is currently studying the effects of carbon dioxide buildup as well as exploring other commercial applications for the fiber optic sensor.

Carbon nanotube sensors integrated inside a microfluidic channel for water quality monitoring

NASA Astrophysics Data System (ADS)

Liu, Yu; Li, Xinghui; Dokmeci, Mehmet R.; Wang, Ming L.

2011-04-01

Single-walled carbon nanotubes (SWNTs) with their unique electrical properties and large surface area are remarkable materials for detecting low concentration of toxic and hazardous chemicals (both from the gaseous and liquid phases). Ionic adsorbates in water will attach on to SWNTs and drastically alter their electrical properties. Several SWNTs based pH and chemical sensors have been demonstrated. However, most of them require external components to test and analyze the response of SWNTs to ions inside the liquid samples. Here, we report a water quality monitoring sensor composed of SWNTs integrated inside microfluidic channels and on-chip testing components with a wireless transmission board. To detect multiple analytes in water requires the functionalization of SWNTs with different chemistries. In addition, microfluidic channels are used to guide liquid samples to individual nanotube sensors in an efficient manner. Furthermore, the microfluidic system enables sample mixing and separation before testing. To realize the nanosensors, first microelectrodes were fabricated on an oxidized silicon substrate. Next, PDMS micro channels were fabricated and bonded on the substrate. These channels can be incorporated with a microfluidic system which can be designed to manipulate different analytes for specific molecule detection. Low temperature, solution based Dielectrophoretic (DEP) assembly was conducted inside this microfluidic system which successfully bridged SWNTs between the microelectrodes. The SWNTs sensors were next characterized with different pH buffer solutions. The resistance of SWNTs had a linearly increase as the pH values ranged from 5 to 8. The nanosensor incorporated within the microfluidic system is a versatile platform and can be utilized to detect numerous water pollutants, including toxic organics and microorganisms down to low concentrations. On-chip processing and wireless transmission enables the realization of a full autonomous system for real time monitoring of water quality.

Magnetic-graphitic-nanocapsule templated diacetylene assembly and photopolymerization for sensing and multicoded anti-counterfeiting

NASA Astrophysics Data System (ADS)

Nie, Xiang-Kun; Xu, Yi-Ting; Song, Zhi-Ling; Ding, Ding; Gao, Feng; Liang, Hao; Chen, Long; Bian, Xia; Chen, Zhuo; Tan, Weihong

2014-10-01

Molecular self-assembly, a process to design molecular entities to aggregate into desired structures, represents a promising bottom-up route towards precise construction of functional systems. Here we report a multifunctional, self-assembled system based on magnetic-graphitic-nanocapsule (MGN) templated diacetylene assembly and photopolymerization. The as-prepared assembly system maintains the unique color and fluorescence change properties of the polydiacetylene (PDA) polymers, while also pursues the superior Raman, NIR, magnetic and superconducting properties from the MGN template. Based on both fluorescence and magnetic resonance imaging (MRI) T2 relaxivity, the MGN@PDA system could efficiently monitor the pH variations which could be used as a pH sensor. The MGN@PDA system further demonstrates potential as unique ink for anti-counterfeiting applications. Reversible color change, strong and unique Raman scattering and fluorescence emission, sensitive NIR thermal response, and distinctive magnetic properties afford this assembly system with multicoded anti-counterfeiting capabilities.Molecular self-assembly, a process to design molecular entities to aggregate into desired structures, represents a promising bottom-up route towards precise construction of functional systems. Here we report a multifunctional, self-assembled system based on magnetic-graphitic-nanocapsule (MGN) templated diacetylene assembly and photopolymerization. The as-prepared assembly system maintains the unique color and fluorescence change properties of the polydiacetylene (PDA) polymers, while also pursues the superior Raman, NIR, magnetic and superconducting properties from the MGN template. Based on both fluorescence and magnetic resonance imaging (MRI) T2 relaxivity, the MGN@PDA system could efficiently monitor the pH variations which could be used as a pH sensor. The MGN@PDA system further demonstrates potential as unique ink for anti-counterfeiting applications. Reversible color change, strong and unique Raman scattering and fluorescence emission, sensitive NIR thermal response, and distinctive magnetic properties afford this assembly system with multicoded anti-counterfeiting capabilities. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03837a

Monitoring of the interconversion of gamma-butyrolactone (GBL) to gamma hydroxybutyric acid (GHB) by Raman spectroscopy.

PubMed

Munshi, Tasnim; Brewster, Victoria L; Edwards, Howell G M; Hargreaves, Michael D; Jilani, Shelina K; Scowen, Ian J

2013-08-01

Gamma-hydroxybutyric acid (GHB) is a drug-of-abuse that has recently become associated with drug-facilitated sexual assault, known as date rape. For this reason the drug is commonly found 'spiked' in alcoholic beverages. When GHB is in solution it may undergo conversion into the corresponding lactone, Gamma-butyrolactone (GBL). Studies have been carried out to determine the detection limits of GHB and GBL in various solutions by Raman spectroscopy and to monitor the interconversion of GHB and GBL in solution with different pH conditions and temperature. In this study, a portable Raman spectrometer was used to study the interconversion of GHB and GBL in water and ethanol solutions as a function of pH, time, and temperature. The aim of this was to determine the optimum pH range for conversion in order to relate this to the pH ranges that the drug is likely to be subjected to, first in spiked beverages and secondly after ingestion in the digestive system. The aim was also to identify a timescale for this conversion in relation to possible scenarios, for example if GHB takes a number of hours to convert to GBL, it is likely for the beverage to be ingested before esterification can take place. GHB and GBL were then spiked into a selection of beverages of known pH in order to study the stability of GHB and GBL in real systems. Copyright © 2012 John Wiley & Sons, Ltd.

Wearable sweat detector device design for health monitoring and clinical diagnosis

NASA Astrophysics Data System (ADS)

Wu, Qiuchen; Zhang, Xiaodong; Tian, Bihao; Zhang, Hongyan; Yu, Yang; Wang, Ming

2017-06-01

Miniaturized sensor is necessary part for wearable detector for biomedical applications. Wearable detector device is indispensable for online health care. This paper presents a concept of an wearable digital health monitoring device design for sweat analysis. The flexible sensor is developed to quantify the amount of hydrogen ions in sweat and skin temperature in real time. The detection system includes pH sensor, temperature sensor, signal processing module, power source, microprocessor, display module and so on. The sweat monitoring device is designed for sport monitoring or clinical diagnosis.

Method for monitoring environmental and corrosion

DOEpatents

Glass, Robert S.; Clarke, Jr., Willis L.; Ciarlo, Dino R.

1995-01-01

A corrosion sensor array incorporating individual elements for measuring various elements and ions, such as chloride, sulfide, copper, hydrogen (pH), etc. and elements for evaluating the instantaneous corrosion properties of structural materials. The exact combination and number of elements measured or monitored would depend upon the environmental conditions and materials used which are subject to corrosive effects. Such a corrosion monitoring system embedded in or mounted on a structure exposed to the environment would serve as an early warning system for the onset of severe corrosion problems for the structure, thus providing a safety factor as well as economic factors. The sensor array is accessed to an electronics/computational system, which provides a means for data collection and analysis.

Continuous monitoring of myocardial acid-base status during intermittent warm blood cardioplegia.

PubMed

Graffigna, A C L; Nollo, G; Pederzolli, C; Ferrari, P; Widesott, L; Antolini, R

2002-06-01

Intermittent warm blood cardioplegia (IWBC) is a well-established technique for myocardial protection during cardiac operations. According to standardized protocols, IWBC administration is currently performed every 15-20 min regardless of any individual variable and in the absence of any instrumental monitoring. We devised a new system for continuous measurement of the acid-base status of coronary sinus blood for on-line evaluation of myocardial oxygenation during IWBC. In 19 patients undergoing cardiac surgery for coronary artery bypass graft and/or valve surgery and receiving IWBC (34-37 degrees C) by antegrade induction (3 min) and retrograde or antegrade maintenance (2 min) every 15 min, continuous monitoring of myocardial oxygenation and acid/base status was performed by means of a multiparameter PO(2), PCO(2), pH, and temperature sensor (Paratrend7 (R), Philips Medical System) inserted into the coronary sinus. Mean cross-clamping time was 76+/-26 min; ischemic time was 13+/-0.2 min. pH decline was not linear, showing an initial fast decline, a point of flexus, and a progressive slow decline. After every ischemic period, the pH adaptation curve showed a complex pattern reaching step-by-step lower minimum levels (7.28+/-0.14 during the first ischemic period, to 7.16+/-0.19 during the third ischemic period - P=0.003). PO(2) decreased rapidly at 90% in 5.0+/-1.2 min after every reperfusion. During ischemia, PCO(2) increased steadily at 1.6+/-0.1 mmHg per minute, with progressively incomplete removal after successive reperfusion, and progressive increase of maximal level (42+/-12 mmHg during the first ischemic period, to 53+/-23 mmHg during the third ischemic period - P=0.05). Myocardial oxygen, carbon dioxide, and pH show marked changes after repeated IWBC. Myocardial ischemia is not completely reversed by standardized reperfusions, as reflected by steady deterioration of PCO(2) and pH after each reperfusion. Progressive increase of reperfusion durations or direct monitoring of myocardial oxygenation could be advisable in cases of prolonged cross-clamping time.

40 CFR 63.8450 - What are my monitoring installation, operation, and maintenance requirements?

Code of Federal Regulations, 2010 CFR

2010-07-01

... electrical connections for continuity, and all mechanical connections for leakage. (d) For each pH... bag leak detection system, you must meet the requirements in paragraphs (e)(1) through (11) of this section. (1) Each triboelectric bag leak detection system must be installed, calibrated, operated, and...

Real time fish pond monitoring and automation using Arduino

NASA Astrophysics Data System (ADS)

Harun, Z.; Reda, E.; Hashim, H.

2018-03-01

Investment and operating costs are the biggest obstacles in modernizing fish ponds in an otherwise very lucrative industry i.e. food production, in this region. Small-scale farmers running on small ponds could not afford to hire workers to man daily operations which usually consists of monitoring water levels, temperature and feeding fish. Bigger scale enterprises usually have some kinds of automation for water monitoring and replacement. These entities have to consider employing pH and dissolved oxygen (DO) sensors to ensure the health and growth of fish, sooner or later as their farms grow. This project identifies one of the sites, located in Malacca. In this project, water, temperature, pH and DO levels are measured and integrated with aerating and water supply pumps using Arduino. User could receive information at predetermined intervals on preferred communication or display gadgets as long as they have internet. Since integrating devices are comparatively not expensive; it usually consists of Arduino board, internet and relay frames and display system, farmer could source these components easily. A sample of two days measurements of temperature, pH and DO levels show that this farm has a high-quality water. Oxygen levels increases in the day as sunshine supports photosynthesis in the pond. With this integration system, farmer need not hire worker at their site, consequently drive down operating costs and improve efficiency.

Aquatic passive sampling of perfluorinated chemicals with polar organic chemical integrative sampler and environmental factors affecting sampling rate.

PubMed

Li, Ying; Yang, Cunman; Bao, Yijun; Ma, Xueru; Lu, Guanghua; Li, Yi

2016-08-01

A modified polar organic chemical integrative sampler (POCIS) could provide a convenient way of monitoring perfluorinated chemicals (PFCs) in water. In the present study, the modified POCIS was calibrated to monitor PFCs. The effects of water temperature, pH, and dissolved organic matter (DOM) on the sampling rate (R s) of PFCs were evaluated with a static renewal system. During laboratory validation over a 14-day period, the uptake kinetics of PFCs was linear with the POCIS. DOM and water temperature slightly influenced POCIS uptake rates, which is in consistent with the theory for uptake into POCIS. Therefore, within a narrow span of DOM and water temperatures, it was unnecessary to adjust the R s value for POCIS. Laboratory experiments were conducted with water over pH ranges of 3, 7, and 9. The R s values declined significantly with pH increase for PFCs. Although pH affected the uptake of PFCs, the effect was less than twofold. Application of the R s value to analyze PFCs with POCIS deployed in the field provided similar concentrations obtained from grab samples.

Fabrication and Evaluation of a Micro(Bio)Sensor Array Chip for Multiple Parallel Measurements of Important Cell Biomarkers

PubMed Central

Pemberton, Roy M.; Cox, Timothy; Tuffin, Rachel; Drago, Guido A.; Griffiths, John; Pittson, Robin; Johnson, Graham; Xu, Jinsheng; Sage, Ian C.; Davies, Rhodri; Jackson, Simon K.; Kenna, Gerry; Luxton, Richard; Hart, John P.

2014-01-01

This report describes the design and development of an integrated electrochemical cell culture monitoring system, based on enzyme-biosensors and chemical sensors, for monitoring indicators of mammalian cell metabolic status. MEMS technology was used to fabricate a microwell-format silicon platform including a thermometer, onto which chemical sensors (pH, O2) and screen-printed biosensors (glucose, lactate), were grafted/deposited. Microwells were formed over the fabricated sensors to give 5-well sensor strips which were interfaced with a multipotentiostat via a bespoke connector box interface. The operation of each sensor/biosensor type was examined individually, and examples of operating devices in five microwells in parallel, in either potentiometric (pH sensing) or amperometric (glucose biosensing) mode are shown. The performance characteristics of the sensors/biosensors indicate that the system could readily be applied to cell culture/toxicity studies. PMID:25360580

STS-77 Flight Day 6

NASA Technical Reports Server (NTRS)

1996-01-01

On this sixth day of the STS-77 mission, the flight crew, Cmdr. John H. Casper, Pilot Curtis L. Brown, Jr., and Mission Specialists Andrew S.W. Thomas, Ph.D., Daniel W. Bursch, Mario Runco, Jr., and Marc Garneau, Ph.D., spend some time relaxing, then go back to working in the Spacehab module and preparing to revisit a small cylindrical satellite that they deployed on the mission's third day. Commander John Casper and Pilot Curt Brown monitor Endeavour's systems. Mission Specialist Mario Runco tests an attitude determination system using the GPS attitude and navigation experiment called GANE. The remaining crew members, Mission Specialists Andy Thomas, Dan Bursch and Marc Garneau monitor the health of experiments ongoing in the Spacehab and on the middeck of the orbiter. The crew also conduct a health check of the Aquatic Research Facility (ARF) which contains starfish, mussels and sea urchins.

A new wireless system for decentralised measurement of physiological parameters from shake flasks

PubMed Central

Vasala, Antti; Panula, Johanna; Bollók, Monika; Illmann, Lutz; Hälsig, Christian; Neubauer, Peter

2006-01-01

Background Shake flasks are widely used because of their low price and simple handling. Many researcher are, however, not aware of the physiological consequences of oxygen limitation and substrate overflow metabolism that occur in shake flasks. Availability of a wireless measuring system brings the possibilities for quality control and design of cultivation conditions. Results Here we present a new wireless solution for the measurement of pH and oxygen from shake flasks with standard sensors, which allows data transmission over a distance of more than 100 metres in laboratory environments. This new system was applied to monitoring of cultivation conditions in shake flasks. The at-time monitoring of the growth conditions became possible by simple means. Here we demonstrate that with typical protocols E. coli shake flask cultures run into severe oxygen limitation and the medium is strongly acidified. Additionally the strength of the new system is demonstrated by continuous monitoring of the oxygen level in methanol-fed Pichia pastoris shake flask cultures, which allows the optimisation of substrate feeding for preventing starvation or methanol overfeed. 40 % higher cell density was obtained by preventing starvation phases which occur in standard shake flask protocols by adding methanol when the respiration activity decreased in the cultures. Conclusion The here introduced wireless system can read parallel sensor data over long distances from shake flasks that are under vigorous shaking in cultivation rooms or closed incubators. The presented technology allows centralised monitoring of decentralised targets. It is useful for the monitoring of pH and dissolved oxygen in shake flask cultures. It is not limited to standard sensors, but can be easily adopted to new types of sensors and measurement places (e.g., new sensor points in large-scale bioreactors). PMID:16504107

The effect of antacid on salivary pH in patients with and without dental erosion after multiple acid challenges.

PubMed

Dhuhair, Sarah; Dennison, Joseph B; Yaman, Peter; Neiva, Gisele F

2015-04-01

To evaluate the effect of antacid swish in the salivary pH values and to monitor the pH changes in subjects with and without dental erosion after multiple acid challenge tests. 20 subjects with tooth erosion were matched in age and gender with 20 healthy controls according to specific inclusion/exclusion criteria. Baseline measures were taken of salivary pH, buffering capacity and salivary flow rate using the Saliva Check System. Subjects swished with Diet Pepsi three times at 10-minute intervals. Changes in pH were monitored using a digital pH meter at 0-, 5-, and 10- minute intervals and at every 5 minutes after the third swish until pH resumed baseline value or 45 minutes relapse. Swishing regimen was repeated on a second visit, followed by swishing with sugar-free liquid antacid (Mylanta Supreme). Recovery times were also recorded. Data was analyzed using independent t-tests, repeated measures ANOVA, and Fisher's exact test (α= 0.05). Baseline buffering capacity and flow rate were not significantly different between groups (P= 0.542; P= 0.2831, respectively). Baseline salivary pH values were similar between groups (P= 0.721). No significant differences in salivary pH values were found between erosion and non-erosion groups in response to multiple acid challenges (P= 0.695) or antacid neutralization (P= 0.861). Analysis of salivary pH recovery time revealed no significant differences between groups after acid challenges (P= 0.091) or after the use of antacid (P= 0.118). There was a highly significant difference in the survival curves of the two groups on Day 2, with the non-erosion group resolving significantly faster than the erosion group (P= 0.0086).

The utility of oesophageal pH monitoring in diagnosing gastroesophageal reflux disease-related chronic cough.

PubMed

Rybka, Aleksandra; Malesa, Kamila; Radlińska, Olga; Krakowiak, Karolina; Grabczak, Elżbieta M; Dąbrowska, Marta; Chazan, Ryszarda

2014-01-01

Chronic cough is a common medical complaint, which may deteriorate patients' quality of life and cause many complications. Gastroesophageal reflux disease (GERD) is one of the frequent reasons for chronic cough. Oesophageal pH monitoring is one of the diagnostic methods performed to confirm diagnosis of GERD-related cough. The aim of the study was to analyse the utility of oesophageal pH monitoring in diagnosing GERD-related cough and to identify the most sensitive pH monitoring parameters for diagnosing GERD-related cough. 24-hour oesophageal pH monitoring was performed in 204 patients suffering from chronic cough. The group consisted of 65% females and the median age was 59 years. An acid reflux episode was defined as a rapid drop in pH to a value below 4 for at least 12 seconds. The diagnosis of GERD was based on total fraction time of pH < 4, upright or supine fraction time of pH < 4, or DeMeester score. The diagnosis of GERD-related cough was made if cough episodes, marked by the patients, appeared within 2 minutes after the reflux. The association between reflux episode and appearance of cough was analysed using two parameters: symptom index (SI ≥ 50%) and/or symptom association probability (SAP ≥ 95%). Based on results of pH monitoring, 135 patients (135/204, 66%) were diagnosed with GERD. Among them, 117 patients (117/135, 87%) were diagnosed based on DeMeester score. Among patients with GERD, 61 patients met the criteria of GERD-related cough (61/135, 45%), i.e. 30% of the group as a whole. Thirty-six patients (36/61, 59%) were diagnosed based on SAP, 12 patients (20%) based on SI, and 13 (21%) based on both parameters. Spearman rank correlation coefficient for SAP ≥ 95% and SI ≥ 50% was 0.46 (p < 0.05). Based on pH monitoring results, GERD was diagnosed twice as often as GERD-related cough. SAP index is more sensitive than SI for the diagnosis of GERD-related cough.

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

NASA Astrophysics Data System (ADS)

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).

Role of intragastric and intraoesophageal alkalinisation in the genesis of complications in Barrett's columnar lined lower oesophagus.

PubMed Central

Attwood, S E; Ball, C S; Barlow, A P; Jenkinson, L; Norris, T L; Watson, A

1993-01-01

Patients with Barrett's columnar lined lower oesophagus have severe acid gastrooesophageal reflux and may develop complications, including ulceration, stricture, and carcinoma. The aim of this study was to establish if a relationship exists between the pH profile in the oesophagus and stomach and the development of complications in patients with Barrett's columnar lined lower oesophagus. Twenty four hour ambulatory oesophageal pH monitoring was performed in 26 patients with Barrett's columnar lined lower oesophagus and combined with 24 hour ambulatory gastric pH monitoring in 16. Ten of the 26 with Barrett's columnar lined lower oesophagus had complications including stricture (eight), deep ulceration (one), and carcinoma (one). Oesophageal acid exposure (% time < pH 4) was similar in patients with or without complications (19.2% v 19.3% p > 0.05). Oesophageal alkaline exposure (% time > pH 7) was greater in patients with complications (24.2% v 8.4% p > 0.05). Of the 16 patients who underwent gastric pH monitoring there was a clear relationship between gastric and oesophageal alkalinisation in 13. These results support the hypothesis that complications in Barrett's columnar lined lower oesophagus develop in association with increased exposure of the oesophagus to an alkaline environment which appears to be secondary to duodenogastric reflux. The routine use of 24 hour ambulatory gastric pH monitoring in conjunction with oesophageal pH monitoring can help identify those patients at risk. PMID:8432439

40 CFR 63.8600 - What are my monitoring installation, operation, and maintenance requirements?

Code of Federal Regulations, 2010 CFR

2010-07-01

... continuity, and all mechanical connections for leakage. (d) For each pH measurement device, you must meet the... integrity and all electrical connections for continuity. (e) For each bag leak detection system, you must... leak detection system must be installed, calibrated, operated, and maintained according to the “Fabric...

Real Time Monitoring System of Pollution Waste on Musi River Using Support Vector Machine (SVM) Method

NASA Astrophysics Data System (ADS)

Fachrurrozi, Muhammad; Saparudin; Erwin

2017-04-01

Real-time Monitoring and early detection system which measures the quality standard of waste in Musi River, Palembang, Indonesia is a system for determining air and water pollution level. This system was designed in order to create an integrated monitoring system and provide real time information that can be read. It is designed to measure acidity and water turbidity polluted by industrial waste, as well as to show and provide conditional data integrated in one system. This system consists of inputting and processing the data, and giving output based on processed data. Turbidity, substances, and pH sensor is used as a detector that produce analog electrical direct current voltage (DC). Early detection system works by determining the value of the ammonia threshold, acidity, and turbidity level of water in Musi River. The results is then presented based on the level group pollution by the Support Vector Machine classification method.

Application of a microcomputer-based system to control and monitor bacterial growth.

PubMed

Titus, J A; Luli, G W; Dekleva, M L; Strohl, W R

1984-02-01

A modular microcomputer-based system was developed to control and monitor various modes of bacterial growth. The control system was composed of an Apple II Plus microcomputer with 64-kilobyte random-access memory; a Cyborg ISAAC model 91A multichannel analog-to-digital and digital-to-analog converter; paired MRR-1 pH, pO(2), and foam control units; and in-house-designed relay, servo control, and turbidimetry systems. To demonstrate the flexibility of the system, we grew bacteria under various computer-controlled and monitored modes of growth, including batch, turbidostat, and chemostat systems. The Apple-ISAAC system was programmed in Labsoft BASIC (extended Applesoft) with an average control program using ca. 6 to 8 kilobytes of memory and up to 30 kilobytes for datum arrays. This modular microcomputer-based control system was easily coupled to laboratory scale fermentors for a variety of fermentations.

Application of a Microcomputer-Based System to Control and Monitor Bacterial Growth

PubMed Central

Titus, Jeffrey A.; Luli, Gregory W.; Dekleva, Michael L.; Strohl, William R.

1984-01-01

A modular microcomputer-based system was developed to control and monitor various modes of bacterial growth. The control system was composed of an Apple II Plus microcomputer with 64-kilobyte random-access memory; a Cyborg ISAAC model 91A multichannel analog-to-digital and digital-to-analog converter; paired MRR-1 pH, pO2, and foam control units; and in-house-designed relay, servo control, and turbidimetry systems. To demonstrate the flexibility of the system, we grew bacteria under various computer-controlled and monitored modes of growth, including batch, turbidostat, and chemostat systems. The Apple-ISAAC system was programmed in Labsoft BASIC (extended Applesoft) with an average control program using ca. 6 to 8 kilobytes of memory and up to 30 kilobytes for datum arrays. This modular microcomputer-based control system was easily coupled to laboratory scale fermentors for a variety of fermentations. PMID:16346462

Integration of Low-Power ASIC and MEMS Sensors for Monitoring Gastrointestinal Tract Using a Wireless Capsule System.

PubMed

Arefin, Md Shamsul; Redoute, Jean-Michel; Yuce, Mehmet Rasit

2018-01-01

This paper presents a wireless capsule microsystem to detect and monitor the pH, pressure, and temperature of the gastrointestinal tract in real time. This research contributes to the integration of sensors (microfabricated capacitive pH, capacitive pressure, and resistive temperature sensors), frequency modulation and pulse width modulation based interface IC circuits, microcontroller, and transceiver with meandered conformal antenna for the development of a capsule system. The challenges associated with the system miniaturization, higher sensitivity and resolution of sensors, and lower power consumption of interface circuits are addressed. The layout, PCB design, and packaging of a miniaturized wireless capsule, having diameter of 13 mm and length of 28 mm, have successfully been implemented. A data receiver and recorder system is also designed to receive physiological data from the wireless capsule and to send it to a computer for real-time display and recording. Experiments are performed in vitro using a stomach model and minced pork as tissue simulating material. The real-time measurements also validate the suitability of sensors, interface circuits, and meandered antenna for wireless capsule applications.

pH-responsive hydrogel coated fiber Bragg grating-based chemo mechanical sensor bioreactor applications

NASA Astrophysics Data System (ADS)

Kishore, P. V. N.; Sai Shankar, M.

2017-04-01

This paper describes a fiber optics based pH sensor by using wavelength modulated techniques. Fiber Bragg grating (FBG) is functionalized with a stimulus responsive hydrogel which induces a strain on FBG due to mechanical expansion of the gel in response to ambient pH changes. The gel is synthesized from the blends of Poly (vinyl alcohol)/Poly (acrylic acid). The induced strain results in a shift of FBG reflected peak which is monitored by an interrogator. The sensor system shows a good linearity in acidic pH range of 3 to 7 with a sensitivity of 12.16pm/pH. Besides that it shows good repeatability which proves it to be fit for pH sensing applications.

A short-term in situ CO2 enrichment experiment on Heron Island (GBR)

PubMed Central

Kline, David I.; Teneva, Lida; Schneider, Kenneth; Miard, Thomas; Chai, Aaron; Marker, Malcolm; Headley, Kent; Opdyke, Brad; Nash, Merinda; Valetich, Matthew; Caves, Jeremy K.; Russell, Bayden D.; Connell, Sean D.; Kirkwood, Bill J.; Brewer, Peter; Peltzer, Edward; Silverman, Jack; Caldeira, Ken; Dunbar, Robert B.; Koseff, Jeffrey R.; Monismith, Stephen G.; Mitchell, B. Greg; Dove, Sophie; Hoegh-Guldberg, Ove

2012-01-01

Ocean acidification poses multiple challenges for coral reefs on molecular to ecological scales, yet previous experimental studies of the impact of projected CO2 concentrations have mostly been done in aquarium systems with corals removed from their natural ecosystem and placed under artificial light and seawater conditions. The Coral–Proto Free Ocean Carbon Enrichment System (CP-FOCE) uses a network of sensors to monitor conditions within each flume and maintain experimental pH as an offset from environmental pH using feedback control on the injection of low pH seawater. Carbonate chemistry conditions maintained in the −0.06 and −0.22 pH offset treatments were significantly different than environmental conditions. The results from this short-term experiment suggest that the CP-FOCE is an important new experimental system to study in situ impacts of ocean acidification on coral reef ecosystems. PMID:22639723

Imaging of dynamic ion signaling during root gravitropism.

PubMed

Monshausen, Gabriele B

2015-01-01

Gravitropic signaling is a complex process that requires the coordinated action of multiple cell types and tissues. Ca(2+) and pH signaling are key components of gravitropic signaling cascades and can serve as useful markers to dissect the molecular machinery mediating plant gravitropism. To monitor dynamic ion signaling, imaging approaches combining fluorescent ion sensors and confocal fluorescence microscopy are employed, which allow the visualization of pH and Ca(2+) changes at the level of entire tissues, while also providing high spatiotemporal resolution. Here, I describe procedures to prepare Arabidopsis seedlings for live cell imaging and to convert a microscope for vertical stage fluorescence microscopy. With this imaging system, ion signaling can be monitored during all phases of the root gravitropic response.

Development of a novel colorimetric sensor based on alginate beads for monitoring rainbow trout spoilage.

PubMed

Majdinasab, Marjan; Hosseini, Seyed Mohammad Hashem; Sepidname, Marziyeh; Negahdarifar, Manizheh; Li, Peiwu

2018-05-01

Alginate is a non-toxic, renewable, and linear copolymer obtained from the brown algae Laminaria digitata that can be easily shaped into beads. Its good gel forming properties have made it useful for entrapping food and pharmaceutical ingredients. In this study, alginate beads were used in a novel application as a colorimetric sensor in food intelligent packaging. Colorimetric sensor was developed through entrapping red cabbage extract as a pH indicator in alginate beads. The pH indicator beads were used in rainbow trout packaging for monitoring fillets spoilage. Color change of beads during fish storage was measured using the CIELab method. The alginate bead colorimetric sensor is validated by measuring total volatile basic nitrogen (TVB-N) levels and microbial populations in fish samples. Moreover, peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) were evaluated during storage. Results indicated that increasing the bacterial population during storage and production of proteolytic enzymes resulted in protein degradation, accumulation of volatile amine compounds, increase in the pH and finally color change of alginate beads. The values of TVB-N, pH, PV and TBARS increased with time of storage. The results of TVB-N and microbial growth were in accordance with color change of beads and CIELab data. Therefore, the proposed system enjoys a high sensitivity to pH variations and is capable of monitoring the spoilage of fish or other protein-rich products through its wide range of color changes. The alginate beads containing the red cabbage extract can, thus, be used as a low-cost colorimetric sensor for intelligent packaging applications.

Method for monitoring environmental and corrosion

DOEpatents

Glass, R.S.; Clarke, W.L. Jr.; Ciarlo, D.R.

1995-08-01

A corrosion sensor array is described incorporating individual elements for measuring various elements and ions, such as chloride, sulfide, copper, hydrogen (pH), etc. and elements for evaluating the instantaneous corrosion properties of structural materials. The exact combination and number of elements measured or monitored would depend upon the environmental conditions and materials used which are subject to corrosive effects. Such a corrosion monitoring system embedded in or mounted on a structure exposed to the environment would serve as an early warning system for the onset of severe corrosion problems for the structure, thus providing a safety factor as well as economic factors. The sensor array is accessed to an electronics/computational system, which provides a means for data collection and analysis. 7 figs.

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

PubMed

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.

Experimental Microfluidic System

NASA Technical Reports Server (NTRS)

Culbertson, Christopher; Gonda, Steve; Ramsey, John Michael

2005-01-01

The ultimate goal of this project is to integrate microfluidic devices with NASA's space bioreactor systems. In such a system, the microfluidic device would provide realtime feedback control of the bioreactor by monitoring pH, glucose, and lactate levels in the cell media; and would provide an analytical capability to the bioreactor in exterrestrial environments for monitoring bioengineered cell products and health changes in cells due to environmental stressors. Such integrated systems could be used as biosentinels both in space and on planet surfaces. The objective is to demonstrate the ability of microfabricated devices to repeatedly and reproducibly perform bead cytometry experiments in micro, lunar, martian, and hypergravity (1.8g).

Software for marine ecological environment comprehensive monitoring system based on MCGS

NASA Astrophysics Data System (ADS)

Wang, X. H.; Ma, R.; Cao, X.; Cao, L.; Chu, D. Z.; Zhang, L.; Zhang, T. P.

2017-08-01

The automatic integrated monitoring software for marine ecological environment based on MCGS configuration software is designed and developed to realize real-time automatic monitoring of many marine ecological parameters. The DTU data transmission terminal performs network communication and transmits the data to the user data center in a timely manner. The software adopts the modular design and has the advantages of stable and flexible data structure, strong portability and scalability, clear interface, simple user operation and convenient maintenance. Continuous site comparison test of 6 months showed that, the relative error of the parameters monitored by the system such as temperature, salinity, turbidity, pH, dissolved oxygen was controlled within 5% with the standard method and the relative error of the nutrient parameters was within 15%. Meanwhile, the system had few maintenance times, low failure rate, stable and efficient continuous monitoring capabilities. The field application shows that the software is stable and the data communication is reliable, and it has a good application prospect in the field of marine ecological environment comprehensive monitoring.

Damage Detection Using Lamb Waves for Structural Health Monitoring

DTIC Science & Technology

2007-03-01

experiments have been reported by Seth Kessler [8]. 2.2 Large Aluminum Plate The second experiment included a 2024-0 aluminum plate with dimensions of...Mechanical Engineering Congress , (IMECE2002- 39017) (17-22 November 2002). 6. Kessler , Seth S. Piezoelectric-Based In-Situ Damage Detection of...Composite Materials for Structural Health Monitoring Systems. Ph.D. thesis, Massachusetts Institute of Technology, January 2002. 7. Kessler , Seth S. “Metis

Rhodamine-based fluorescent probe for direct bio-imaging of lysosomal pH changes.

PubMed

Shi, Xue-Lin; Mao, Guo-Jiang; Zhang, Xiao-Bing; Liu, Hong-Wen; Gong, Yi-Jun; Wu, Yong-Xiang; Zhou, Li-Yi; Zhang, Jing; Tan, Weihong

2014-12-01

Intracellular pH plays a pivotal role in various biological processes. In eukaryotic cells, lysosomes contain numerous enzymes and proteins exhibiting a variety of activities and functions at acidic pH (4.5-5.5), and abnormal variation in the lysosomal pH causes defects in lysosomal function. Thus, it is important to investigate lysosomal pH in living cells to understand its physiological and pathological processes. In this work, we designed a one-step synthesized rhodamine derivative (RM) with morpholine as a lysosomes tracker, to detect lysosomal pH changes with high sensitivity, high selectivity, high photostability and low cytotoxicity. The probe RM shows a 140-fold fluorescence enhancement over a pH range from 7.4 to 4.5 with a pKa value of 5.23. Importantly, RM can detect the chloroquine-induced lysosomal pH increase and monitor the dexamethasone-induced lysosomal pH changes during apoptosis in live cells. All these features demonstrate its value of practical application in biological systems. Copyright © 2014 Elsevier B.V. All rights reserved.

Non-invasive pH determination adjacent to degradable biomaterials in vivo.

PubMed

Bartsch, Ivonne; Willbold, Elmar; Rosenhahn, Bodo; Witte, Frank

2014-01-01

An appropriate pH level is an important prerequisite for the physiologal functioning of cells and tissues. Changes in the extracellular pH often lead to specific cellular reactions and an altered metabolism of cells and tissues influences the extracellular pH range. Thus a method to monitor the extracellular pH is a valuable tool to track specific tissue reactions. In this article we describe a method for the determination of the pH range adjacent to degradable biomaterials using wireless in vivo imaging. Using hairless but immunocompetent mice the fluorophor 5-(6)-carboxy SNARF-1 and the in vivo fluorescence and multispectral acquisition and analysis system Maestro it is possible to track shifts in pH in small living animals over a longer period of time. This method is especially suitable for studies which focus on the interaction of degrading biomaterials with their adjacent tissues. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

System metabolism in the Kanawha River basin: comparing two models

EPA Science Inventory

Resource managers and regulatory agencies typically monitor aquatic ecosystem condition using a combination of measures that describe stream structure (e.g. physical habitat variables, species richness metrics) and physiochemical properties (e.g., pH, DO, turbidity). Recently, me...

African-Americans, Hispanic Americans, and non-Hispanic whites without GERD or reflux symptoms have equivalent 24-h pH esophageal acid exposure.

PubMed

Vega, Kenneth J; Langford, Tracy; Palacio, Carlos; Watts, Janet; Jamal, M Mazen

2013-12-01

Ambulatory esophageal pH monitoring is, currently, the recommended diagnostic exam for gastroesophageal reflux disease. Data are currently available for African-American (AA) and non-Hispanic white (nHw) volunteers among United States ethnic groups. The purpose of this study was to obtain normal values of 24-h esophageal pH by monitoring healthy adult Hispanic American (HA) volunteers and to compare these with values obtained from healthy AA and nHw volunteers to determine if ethnic variation exists in 24-h esophageal pH. 24-h Dual esophageal pH monitoring was performed for healthy AA, HA, and nHw. Values for total number of reflux episodes, episodes longer than 5 min, total reflux time, and longest reflux episode in the proximal and/or distal esophagus were obtained for all groups. Differences between groups were considered significant if p<0.05. One-hundred and thirty-six subjects volunteered and completed 24-h pH testing. Fifty-three were AA, 25 HA, and 58 nHw, with males accounting for 52, 47, and 47%, respectively, of each group. AA were older than nHw only and nHw had a lower body mass index than both AA and HA. Shorter study duration was observed for HA than for AA and nHw. No difference was observed between ethnic groups for any measured pH data in the proximal or distal esophagus. No difference exists in values obtained during esophageal pH monitoring among healthy AA, HA, and nHw. This indicates that currently accepted normal values of ambulatory esophageal pH monitoring can be used for all major United States ethnic groups without compromising diagnostic accuracy.

Describing temporal variation in reticuloruminal pH using continuous monitoring data.

PubMed

Denwood, M J; Kleen, J L; Jensen, D B; Jonsson, N N

2018-01-01

Reticuloruminal pH has been linked to subclinical disease in dairy cattle, leading to considerable interest in identifying pH observations below a given threshold. The relatively recent availability of continuously monitored data from pH boluses gives new opportunities for characterizing the normal patterns of pH over time and distinguishing these from abnormal patterns using more sensitive and specific methods than simple thresholds. We fitted a series of statistical models to continuously monitored data from 93 animals on 13 farms to characterize normal variation within and between animals. We used a subset of the data to relate deviations from the normal pattern to the productivity of 24 dairy cows from a single herd. Our findings show substantial variation in pH characteristics between animals, although animals within the same farm tended to show more consistent patterns. There was strong evidence for a predictable diurnal variation in all animals, and up to 70% of the observed variation in pH could be explained using a simple statistical model. For the 24 animals with available production information, there was also a strong association between productivity (as measured by both milk yield and dry matter intake) and deviations from the expected diurnal pattern of pH 2 d before the productivity observation. In contrast, there was no association between productivity and the occurrence of observations below a threshold pH. We conclude that statistical models can be used to account for a substantial proportion of the observed variability in pH and that future work with continuously monitored pH data should focus on deviations from a predictable pattern rather than the frequency of observations below an arbitrary pH threshold. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Online PH measurement technique in seawater desalination

NASA Astrophysics Data System (ADS)

Wang, Haibo; Wu, Kaihua; Hu, Shaopeng

2009-11-01

The measurement technology of pH is essential in seawater desalination. Glass electrode is the main pH sensor in seawater desalination. Because the internal impedance of glass electrode is high and the signal of pH sensor is easy to be disturbed, a signal processing circuit with high input impedance was designed. Because of high salinity of seawater and the characteristic of glass electrode, ultrasonic cleaning technology was used to online clean pH sensor. Temperature compensation was also designed to reduce the measurement error caused by variety of environment temperature. Additionally, the potential drift of pH sensor was analyzed and an automatic calibration method was proposed. In order to online monitor the variety of pH in seawater desalination, three operating modes were designed. The three modes are online monitoring mode, ultrasonic cleaning mode and auto-calibration mode. The current pH in seawater desalination was measured and displayed in online monitoring mode. The cleaning process of pH sensor was done in ultrasonic cleaning mode. The calibration of pH sensor was finished in auto-calibration mode. The result of experiments showed that the measurement technology of pH could meet the technical requirements for desalination. The glass electrode could be promptly and online cleaned and its service life was lengthened greatly.

Alkaline pH sensor molecules.

PubMed

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.

Net community calcification and production rates from Palmyra Atoll using a boundary layer gradient flux approach

NASA Astrophysics Data System (ADS)

Takeshita, Y.; McGillis, W. R.; Martz, T. R.; Price, N.; Smith, J.; Donham, E. M.

2016-02-01

Coral reefs are a highly dynamic system, where large variability in environmental conditions (e.g. pH) occurs on timescales of minutes to hours. Yet, techniques that are capable of monitoring reef calcification rates without artificial confinement on the same frequency are scarce. Here, we present a 2 week time series of sub-hourly, in situ benthic net community production (Pnet) and net community calcification (Gnet) rates from a reef terrace at Palmyra Atoll using the Benthic Ecosystem and Acidification Monitoring System (BEAMS). The net metabolism rates reported here are measured under natural conditions, without any alterations to the environment (e.g. light, flow, pH). The BEAMS measures the chemical gradient and the current velocity profile in the benthic boundary layer using autonomous sensors to calculate the chemical flux from the benthos. The O2 and total alkalinity (TA) fluxes were used to calculate Pnet and Gnet, respectively; TA gradients were calculated from pH and O2 measurements. Gnet can be constrained to better than 3 mmol CaCO3 m-2 hr-1 using this approach, based on three simultaneous BEAMS deployments. A clear diel cycle of Gnet was observed, where the peak day time Gnet and average nighttime Gnet were 14 and 1 mmol CaCO3 m-2 hr-1, respectively. Integrated daily Gnet ranged from 76 to 219 mmol CaCO3 m-2 d-1, with an average of 107 ± 14 mmol CaCO3 m-2 d-1. Light had the strongest control over Gnet, with current velocity having a smaller yet noticeable effect. During the deployment, pH varied by 0.16 (ranged between 7.92 and 8.08), and a significant positive relationship was observed between pH and Gnet. However, pH was also positively correlated with current velocity and Pnet, making it difficult to determine if natural variability in pH was significantly affecting Gnet on the timescale of days to weeks.

Yield of prolonged wireless pH monitoring in achalasia patients successfully treated with pneumatic dilation

PubMed Central

Franchina, Marianna; Elvevi, Alessandra; Pugliese, Delia; Tenca, Andrea; Conte, Dario; Penagini, Roberto

2016-01-01

Background Gastro-oesophageal reflux disease (GORD) is a long-term complication of achalasia treatments. The aim of our study was to evaluate the yield of prolonged wireless pH monitoring in patients with successfully treated achalasia and its influence on proton pump inhibitor (PPI) use. Methods Twenty-five patients with achalasia who underwent prolonged wireless pH monitoring after a successful treatment with pneumatic dilation were enrolled. pH variables were analysed in the first 24 hours of monitoring to determine if tracings were indicative of GORD; the same variables were analysed in the following 24-hour period in order to obtain a worst-day diagnosis of GORD. PPI therapy before and after the test was recorded. Results Five out of 25 patients had GORD diagnosis during the first day of monitoring and four of them had oesophagitis at endoscopy. During the following days of monitoring four more patients had a diagnosis of GORD. Out of the 25 patients, PPIs were started after the test in six asymptomatic GORD-positive ones, whereas prescription of PPIs was stopped without detrimental effect on symptoms in three GORD-negative patients. Conclusions Prolonged wireless pH monitoring is a useful test to be added to endoscopy in order to evaluate GORD and to optimise antisecretory treatment in successfully treated achalasia patients. PMID:29026592

A confocal microscopy based method to monitor extracellular pH in fungal biofilms.

PubMed

Schlafer, Sebastian; Kamp, Anja; Garcia, Javier E

2018-04-19

pH in fungal biofilms is important for a variety of fungal infections and industrial applications involving fungal biofilms, but to date, it has never been measured directly inside the biofilm matrix. In the present study, a new methodology was developed allowing for confocal microscopy based monitoring of extracellular pH inside fungal biofilms. Monospecies biofilms of Aspergillus fumigatus, Candida albicans, Candida dubliniensis and Cryptococcus neoformans were stained with the pH dependent ratiometric probe C-SNARF-4, imaged with a confocal microscope, and a digital image analysis procedure was developed to determine pH in the extracellular matrix. As a proof of concept, pH developments at the biofilm-substratum interface were monitored for one h after exposure to glucose. Observed pH drops differed considerably between the different species and also between replicate biofilms of the same species. C. albicans biofilms showed the highest acidogenicity, with pH drops occurring much faster than in planktonic culture. pH ratiometry with C-SNARF-4 is a valuable tool to get insight into fungal biofilm metabolism and may shed new light on both disease-related and industrially relevant processes in fungal biofilms.

PP-16 WEAK ACID REFLUX A TRIGGER FOR RECURRENT RESPIRATORY DISEASES IN CHILDREN.

PubMed

Kostovski, Aco; Zdraveska, Nikolina

2015-10-01

The main advantage of multichannel intraluminar impedance (MII) compared with pH monitoring is its ability to detect both acid and non-acid gastroesophageal reflux (GER) and to determine the characteristics of reflux (liquid or gas). To compare the value of pH monitoring and MII for diagnosis of GER in children who present with refractory respiratory symptoms. A prospective study that included 37 patients, aged 4.25 ± 3.15 years, using combined MII-pH monitoring was performed. Patients were referred for investigation because of suspected GER as the etiology of recurrent respiratory diseases, including recurrent obstructive bronchitis, recurrent pneumonia, laryngitis, and chronic cough. We analyzed the percentage of time during which the pH was less than 4, the numeric and percentile values of acid, weak acid, and non-acid reflux episodes, and the values of liquid and mixed reflux. Diagnostic values were determined separately for pH monitoring and MII using Fisher's exact test. Reflux was detected in 31 patients. pH monitoring was positive in 20 patients (% time during which pH <4 was 17.72 ± 12.06) and negative in 17 patients (2.93% ± 1.67). Both pH and MII were positive in 19 patients: in 11 patients, MII was positive and pH was negative, and in 6 patients, both were negative. Fisher's exact test showed significant statistical difference and superiority of MII in diagnosing GER (p = 0.033). Out of 30 patients with MII-positive results, 15 had both acid and weak acid reflux episodes, 3 had only acid reflux, 8 had weak acid reflux, and 3 had non-acid reflux. Sixteen patients had mixed (liquid and gas) reflux, and 14 had both liquid and mixed reflux. This study suggests that significant numbers of GER include weak acid reflux that cannot be detected by pH probes alone. The weak acid reflux could be a trigger for recurrent respiratory symptoms. Combining pH with MII monitoring is a valuable diagnostic method for diagnosing GER in children.

An in vivo quantitative Raman-pH sensor of arterial blood based on laser trapping of erythrocytes.

PubMed

Lin, Manman; Xu, Bin; Yao, Huilu; Shen, Aiguo; Hu, Jiming

2016-05-10

We report on a continuous and non-invasive approach in vivo to monitor arterial blood pH based on the laser trapping and Raman detection of single live erythrocytes. A home-built confocal laser tweezers Raman system (LTRS) is applied to trace the live erythrocytes at different pH values of the extracellular environment to record their corresponding Raman changes in vitro and in vivo. The analysis results in vitro show that when the extracellular environment pH changes from 6.5 to 9.0, the Raman intensity ratio (R1603, 1616 = I1603/I1616) of single erythrocytes decrease regularly; what is more, there is a good linear relationship between these two variables, and the linearity is 0.985, which is also verified successfully via in vivo Raman measurements. These results demonstrate that the Raman signal of single live erythrocytes is possible as a marker of the extracellular pH value. This in vivo and quantitative Raman-pH sensor of arterial blood will be an important candidate for monitoring the acid-base status during the treatment of ill patients and in some major surgeries because of its continuous and non-invasive characters.

Detecting change in water quality from implementation of limestone treatment systems in a coal-minded watershed

USGS Publications Warehouse

Cravotta,, Charles A.; Weitzel, Jeffrey B.

2000-01-01

During 1996-97, a variety of limestone-based treatment systems were implemented to neutralize acidic mine drainage and reduce the transport of dissolved metals in the northern part of the Swatara Creek watershed, which drains a 43-mi2 (112-km2) area in the Southern Anthracite Field upstream from Ravine, Pa. Since 1996, the current project has monitored water quality upstream and downstream of each treatment and at integrator sites on lower reaches of Swatara Creek. Continuous measurements of pH and specific conductance and periodic sampling for alkalinity, acidity, sulfate, and metals upstream and downstream of each treatment system show that (1) open limestone channels and limestone-sand dosing generally had negligible effects on water quality and (2) limestone diversion wells and limestone drains generally were effective at producing near-neutral pH and attenuating dissolved metals during baseflow but were less effective during stormflow conditions. Storm runoff in this area commonly is acidic, and, as streamflow volume increases during stormflow conditions, a smaller fraction of total flow is treated and (or) residence time in the treatment system is reduced. Monitoring on the mainstem of Swatara Creek indicates watershed-scale effects owing primarily to changes in mining practices and secondarily to watershed-wide implementation of treatment systems. Most underground mines in the Swatara Creek Basin were abandoned before 1960 and are presently flooded. Drainage from these mines contributes substantially to baseflow in Swatara Creek. For Swatara Creek at Ravine, Pa., which is immediately downstream of the mined area, long-term data collected since 1959 indicate sulfate concentration declined from about 150 mg/L in 1959 to 75 mg/L in 1999; pH increased sharply from 3.5-4.4 (median ~4) to 4.6-7.0 (median ~6) after 1975. These trends resulted from a decline in pyrite oxidation and the onset of carbonate buffering. Because these long-term attenuation processes have had such a pronounced effect on water quality in Swatara Creek, the effects of recent implementation of limestone treatments are difficult to detect at a watershed scale. Nevertheless, during ecological surveys prior to 1991, no fish were found in Swatara Creek at Ravine. Only six species of fish were found in 1994 and 1996. However, increasing numbers of fish have been found annually since 1996. In 1999, 21 species of fish were documented. The recent monitoring on the mainstem of Swatara Creek indicates the limestone treatments mitigate extreme fluctuations in pH during storm events; however, additional buffering capacity is needed to maintain near-neutral pH of Swatara Creek during large storm events. Concentration 2 of sulfate, specific conductance, and pH are inversely related to streamflow at Ravine, indicating dilution and acidification during stormflow. Declines in stream-water pH to values approaching 5.0 could result in the remobilization of adsorbed or precipitated metals associated with sediments; declines in pH below 5.0 could cause injury to aquatic organisms. Generally, to maintain stream pH during storms, additional or larger limestone diversion wells could be constructed to begin or increase alkalinity production as the stream stage rises and/or additional or larger limestone drains could be constructed to produce greater amounts of alkalinity and enhance the buffering capacity of baseflow.

Long-term, High Frequency, High Precision pH Measurements on the MBARI deep-water FOCE Experiment at the MARS Cabled Observatory in Monterey Bay, CA

NASA Astrophysics Data System (ADS)

Peltzer, E. T.; Maughan, T.; Barry, J. P.; Brewer, P. G.; Headley, K. L.; Herlien, R.; Kirkwood, W. J.; Matsumoto, G. I.; O'Reilly, T. C.; Salamy, K. A.; Scholfield, J.; Shane, F. F.; Walz, P. M.

2012-12-01

The MBARI deep-water FOCE experiment was deployed on the MARS cabled observatory in Monterey Bay on May 4th, 2011. It has been in continuous operation (excluding a few minor shore based power outages) ever since. During the fifteen months of deployment, we have been able to observe both the daily variation in pH in response to water mass movements associated with the semi-diurnal tides, internal waves and longer-term trends as a function of the seasonal variations in the water masses within the Monterey Bay Canyon. Our experimental site is located at 890 meters, just below the oxygen minimum for Monterey Bay, and we clearly see the anticipated inverse correlation between seawater temperature and pH. Daily variation in pH is on the order of 0.020-0.030 pH units with longer term trends adding an additional variation of similar magnitude. Instrumentation on this experiment included two CTDs with oxygen sensors (Sea-Bird 52). One CTD is mounted on the external FOCE framework to measure the background conditions, and one CTD is installed within the FOCE pH control area to monitor the experimentally manipulated conditions. In addition, 6 MBARI modified Sea-Bird 18 pH sensors were mounted on the FOCE apparatus. Four of these pH sensors monitored pH inside the experimental chamber and two monitored the external background seawater conditions. Although we originally intended to conduct several in situ CO2 enrichment experiments to study the impact of ocean acidification on the benthic biology and then recover the apparatus after one year, unanticipated changes in the ship schedule have left the FOCE experiment in place for nearly fifteen months at the time of this writing. Throughout this time period, all sensor data has been logged by the MBARI Shore-Side Data System (SSDS) resulting in the longest continuous record of high precision pH measurements in the intermediate water column. We present an analysis of the data obtained from this unique data set, and discuss our in-situ calibration techniques used to compensate for long term sensor drift associated with the reference electrode.

A monitor for continuous measurement of temperature, pH, and conductance of wet precipitation: Preliminary results from the Adirondack Mountains, New York

USGS Publications Warehouse

Johnsson, P.A.; Reddy, M.M.

1990-01-01

This report describes a continuous wet-only precipitation monitor designed by the U.S. Geological Survey to record variations in rainfall temperature, pH, and specific conductance at 1-min intervals over the course of storms. Initial sampling in the Adirondack Mountains showed that rainfall acidity varied over the course of summer storms, with low initial pH values increasing as storm intensity increased.This report describes a continuous wet-only precipitation monitor designed by the U.S. Geological Survey to record variations in rainfall temperature, pH, and specific conductance at 1-min intervals over the course of storms. Initial sampling in the Adirondack Mountains showed that rainfall acidity varied over the course of summer storms, with low initial pH values increasing as storm intensity increased.

Monitoring the Rate Solvolytic Decomposition of Benzenediazonium Tetrafluoroborate in Aqueous Media Using a pH Electrode

ERIC Educational Resources Information Center

Wiseman, Floyd L.

2005-01-01

A lab rotary experiment using the pH measurements of an aqueous solution to monitor the course of a solvolytic reaction was conducted. This experiment allowed the students to gain experience in taking precise pH measurement, to use nonlinear analysis techniques for analyzing kinetic data and to use the Arrhenius equation for determination of…

A graphene oxide pH sensor for wound monitoring.

PubMed

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 (<; 0.09 pH units in the worst case) for measurements performed over a period of 4 days.

Feasibility analysis of marine ecological on-line integrated monitoring system

NASA Astrophysics Data System (ADS)

Chu, D. Z.; Cao, X.; Zhang, S. W.; Wu, N.; Ma, R.; Zhang, L.; Cao, L.

2017-08-01

The in-situ water quality sensors were susceptible to biological attachment. Moreover, sea water corrosion and wave impact damage, and many sensors scattered distribution would cause maintenance inconvenience. The paper proposed a highly integrated marine ecological on-line integrated monitoring system, which can be used inside monitoring station. All sensors were reasonably classified, the similar in series, the overall in parallel. The system composition and workflow were described. In addition, the paper proposed attention issues of the system design and corresponding solutions. Water quality multi-parameters and 5 nutrient salts as the verification index, in-situ and systematic data comparison experiment were carried out. The results showed that the data consistency of nutrient salt, PH and salinity was better. Temperature and dissolved oxygen data trend was consistent, but the data had deviation. Turbidity fluctuated greatly; the chlorophyll trend was similar with it. Aiming at the above phenomena, three points system optimization direction were proposed.

Fabrication of a Miniature Multi-Parameter Sensor Chip for Water Quality Assessment.

PubMed

Zhou, Bo; Bian, Chao; Tong, Jianhua; Xia, Shanhong

2017-01-14

Water contamination is a main inducement of human diseases. It is an important step to monitor the water quality in the water distribution system. Due to the features of large size, high cost, and complicated structure of traditional water determination sensors and devices, it is difficult to realize real-time water monitoring on a large scale. In this paper, we present a multi-parameter sensor chip, which is miniature, low-cost, and robust, to detect the pH, conductivity, and temperature of water simultaneously. The sensor chip was fabricated using micro-electro-mechanical system (MEMS) techniques. Iridium oxide film was electrodeposited as the pH-sensing material. The atomic ratio of Ir(III) to Ir(IV) is about 1.38 according to the X-ray photoelectron spectroscopy (XPS) analysis. The pH sensing electrode showed super-Nernstian response (-67.60 mV/pH) and good linearity (R² = 0.9997), in the range of pH 2.22 to pH 11.81. KCl-agar and epoxy were used as the electrolyte layer and liquid junction for the solid-state reference electrode, respectively, and its potential stability in deionized water was 56 h. The conductivity cell exhibited a linear determination range from 21.43 μ S / cm to 1.99 mS / cm , and the electrode constant was 1.566 cm -1 . Sensitivity of the temperature sensor was 5.46 Ω / ° C . The results indicate that the developed sensor chip has potential application in water quality measurements.

Monitoring of interstitial buffer systems using micro-dialysis and infrared spectrometry

NASA Astrophysics Data System (ADS)

Heise, H. M.; Cocchieri, L.; Vahlsing, T.; Ihrig, D.; Elm, J.

2017-02-01

Nowadays, continuous sensing systems are important point-of-care devices for the hospital and personalized patient technology. FTIR-spectrometers have been successfully employed for the development of bed-side systems. In-vivo applications for critically ill patients can be envisaged for analytes and parameters, which are of interest for intensive care such as lactate, urea, pCO2 and pH. The human body maintains the blood pH around 7.4, but for severe pH level changes acidosis or alkalosis can lead to serious health problems. Three different buffer systems exist based on bicarbonate, phosphate and proteins; for the most important bicarbonate and phosphate systems infrared transmission spectra were recorded. By using the CO2 and HCO3 - bands of the bicarbonate spectra, the pH of the harvested biofluid can be predicted using the Henderson-Hasselbalch equation. Furthermore, we studied the solubility of CO2 in aqueous solutions using gas mixtures of N2 and CO2 with known composition within partial pressures of CO2 as relevant for invivo conditions. Thus, values of pCO2 up to 150 mm Hg (200 hPa) with distilled water and a Ringer solution, which is an isotonic electrolyte solution used for medical infusion, were measured at 25 °C and 37 °C (normal body temperature).

Multi-decadal Records of Ocean Acidification and Toxic Heavy Metal Pollution in Coral Cores from Oahu, Hawaii

NASA Astrophysics Data System (ADS)

Stewart, J.; Tolliver, R.; Field, D. B.; Young, C.; Stafford, G.; Day, R. D.

2016-12-01

Monitoring of the physiological/ecological response of marine calcifying organisms to the combination of lower pH and toxic metal pollutants (e.g. Cu and Sn from boat anti-fouling paints) into the oceans requires detailed knowledge of the rates and spatial distribution of ocean acidification (OA) and trace metal composition over time. Yet, measurement of metal concentrations and carbonate system parameters in the modern ocean from seawater bottle data is patchy (e.g. CDIAC/WOCE Carbon Data; http://cdiac.ornl.gov) and there remain few long-term surface water pH monitoring stations; the two longest continuous records of ocean pH extend back less than 30 years (Bermuda - BATS, 31°40'N, 64°10'W; Hawaii - HOTs, 22°45'N, 158°00'W). Much attention has therefore been focused on trace metal and ocean carbonate system proxy development to allow reconstruction of seawater metal content and pH in the past. Of particular promise is the boron isotope (δ11B) pH-proxy measured in marine calcifying organisms such as coral that can be cored enabling multi-decadal, annual-resolution, records of trace element incorporation and seawater pH to be generated. Here we present continuous Cu/Ca and Sn/Ca records in addition to δ11B data from three coral cores of Porites lutea. collected from waters proximal to Oahu, Hawaii. The diagenetic integrity of samples is verified using X-ray diffraction to assess the degree of calcite replacement. These cores reach a maximum depth of 80 cm and represent approximately 80 years of coral growth and seawater chemistry.

An intramolecular charge transfer process based fluorescent probe for monitoring subtle pH fluctuation in living cells.

PubMed

Sun, Mingtai; Du, Libo; Yu, Huan; Zhang, Kui; Liu, Yang; Wang, Suhua

2017-01-01

It is crucial to monitor intracellular pH values and their fluctuation since the organelles of cells have different pH distribution. Herein we construct a new small molecule fluorescent probe HBT-O for monitoring the subtle pH values within the scope of neutral to acid in living cells. The probe exhibited good water solubility, a marked turquoise to olivine emission color change in response to pH, and tremendous fluorescence hypochromatic shift of ∼50nm (1718cm -1 ) as well as the increased fluorescence intensity when the pH value changed from neutral to acid. Thus, the probe HBT-O can distinguish the subtle changes in the range of normal pH values from neutral to acid with significant fluorescence changes. These properties can be attributed to the intramolecular charge transfer (ICT) process of the probe upon protonation in buffer solutions at varied pH values. Moreover, the probe was reversible and nearly non-toxic for living cells. Then the probe was successfully used to detect pH fluctuation in living cells by exhibiting different fluorescence colors and intensity. These findings demonstrate that the probe will find useful applications in biology and biomedical research. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaluation of the pH- and Thermal Stability of the Recombinant Green Fluorescent Protein (GFP) in the Presence of Sodium Chloride

NASA Astrophysics Data System (ADS)

Ishii, Marina; Kunimura, Juliana Sayuri; Jeng, Hélio Tallon; Vessoni Penna, Thereza Christina; Cholewa, Olivia

The thermal stability of recombinant green fluorescent protein (GFP) in sodium chloride (NaCl) solutions at different concentrations, pH, and temperatures was evaluated by assaying the loss of fluorescence intensity as a measure of denaturation. GFP, extracted from Escherichia coli cells by the three-phase partitioning method and purified through a butyl hydrophobic interaction chromatography (HIC) column, was diluted in water for injection (WFI) (pH 6.0-7.0) and in 10 mM buffer solutions (acetate, pH 5.0; phosphate, pH 7.0; and Tris-EDTA, pH 8.0) with 0.9-30% NaCl or without and incubated at 80-95°C. The extent of protein denaturation was expressed as a percentage of the calculated decimal reduction time (D-value). In acetate buffer (pH 4.84 ±0.12), the mean D-values for 90% reduction in GFP fluorescence ranged from 2.3 to 3.6 min, independent of NaCl concentration and temperature. GFP thermal stability diluted in WFI (pH 5.94±0.60) was half that observed in phosphate buffer (pH 6.08±0.60); but in both systems, D-values decreased linearly with increasing NaCl concentration, with D-values (at 80°C) ranging from 3.44, min (WFI) to 6.1 min (phosphate buffer), both with 30% NaCl. However, D-values in Tris-EDTA (pH 7.65±0.17) were directly dependent on the NaCl concentration and 5-10 times higher than D-values for GFP in WFI at 80°C. GFP pH-and thermal stability can be easily monitored by the convenient measure of fluorescence intensity and potentially be used as an indicator to monitor that processing times and temperatures were attained.

Evaluation of pH monitoring as a method of processor control.

PubMed

Stears, J G; Gray, J E; Winkler, N T

1979-01-01

Sensitometry and pH values of the developer solution were compared in controlled over-replenishment, developer depletion, fixer contamination experiments, and on a daily quality control basis. The purpose of these comparisons was to evaluate the potential of pH monitoring as a method of processor control, or a supplement to sensitometry as a method of quality control. Reasonable correlation was found between pH values and film density in two of the three experiments but little or no correlation was found in the third experiment and on a day-to-day basis. The conclusion drawn from these comparisons is that pH monitoring has several limitations which render it unsuitable as a method of daily processor quality control as either a primary or supplementary technique. Sensitometry takes into account all the variables encountered in film processing and is the clear method of choice for processor quality control.

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

PubMed

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

2008-01-01

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

Noninvasive pH monitoring of platelet concentrates: a large field test.

PubMed

Gkoumassi, Effimia; Klein-Bosgoed, Christa; Dijkstra-Tiekstra, Margriet J; de Korte, Dirk; de Wildt-Eggen, Janny

2013-10-01

Developing new quality control methods for platelet concentrates (PCs) can contribute to increasing transfusion safety and efficiency. The aim of this study was to investigate in a large field test the quality of expired PCs and whether 100% noninvasive pH monitoring can be used to predict PC quality. The pH of 13,693 PCs produced for transfusion was monitored daily using Blood Storage, Inc.'s pH sterile, automated fluoroscopic evaluation technology. Upon indication of compromised quality or expiration, PCs were returned and in vitro tests were performed. A total of 998 PCs were returned, of which 962 outdated, 26 had a positive BacT/ALERT reaction, seven had aggregates, one was without swirl, one had low pH, and one had high pH. BacT/ALERT was faster in identifying bacterial contamination than pH measurements. The pH at the end of the storage period was significantly lower than at the beginning. In vitro tests indicated that while the PC quality was acceptable upon expiration, it rapidly declined after expiration. In this setting where the vast majority of PCs were of good quality and within acceptable pH limits, daily, noninvasive routine pH measurement has limited added value in identifying quality-compromised PCs. © 2013 Sanquin Research. Transfusion © 2013 American Association of Blood Banks.

Hydroponic system design with real time OS based on ARM Cortex-M microcontroller

NASA Astrophysics Data System (ADS)

Atmadja, Wiedjaja; Liawatimena, Suryadiputra; Lukas, Jonathan; Nata, Eka Putra Leo; Alexander, Ivan

2017-12-01

Hydroponic is the process of growing plants without soil, plant root flooded or moist with nutrient-rich solutions in inert material. Hydroponics has become a reality for greenhouse growers in virtually all climates. Large hydroponic installations exist throughout the world for growing flowers, vegetables and some short period fruit like tomato and cucumber. In soilless culture, we must maintain stable pH and conductivity level of nutrient solution to make plant grow well, large variation of pH of certain time will poisoned plant. This paper describes development complete automation hydroponic system, from maintaining stable nutrient composition (conductivity and pH), grow light, and monitor plant environment such as CO2, temperature and humidity. The heart of our automation is ARM Cortex-M4 from ST Microelectronic running ARM mbed OS, the official Real Time Operating System (RTOS) for ARM Cortex-M microcontroller. Using RTOS gives us flexibility to have multithreaded process. Results show that system capable to control desired concentration level with variation of less than 3%, pH sensor show good accuracy 5.83% from pH value 3.23-10. Growing light intensity measurement show result 105 μmol/m2/s therefore we need turn on the light at least 17 hours/day to fulfil plant light requirement. RTOS give good performance with latency and jitter less than 15 us, system overall show good performance and accuracy for automating hydroponic plant in vegetative phase of growth.

Raman spectroscopic approach to monitor the in vitro cyclization of creatine → creatinine

NASA Astrophysics Data System (ADS)

Gangopadhyay, Debraj; Sharma, Poornima; Singh, Sachin Kumar; Singh, Pushkar; Tarcea, Nicolae; Deckert, Volker; Popp, Jürgen; Singh, Ranjan K.

2015-01-01

The creatine → creatinine cyclization, an important metabolic phenomenon has been initiated in vitro at acidic pH and studied through Raman spectroscopic and DFT approach. The equilibrium composition of neutral, zwitterionic and protonated microspecies of creatine has been monitored with time as the reaction proceeds. Time series Raman spectra show clear signature of creatinine formation at pH 3 after ∼240 min at room temperature and reaction is faster at higher temperature. The spectra at pH 1 and pH 5 do not show such signature up to 270 min implying faster reaction rate at pH 3.

Monitoring data transfer latency in CMS computing operations

DOE PAGES

Bonacorsi, Daniele; Diotalevi, Tommaso; Magini, Nicolo; ...

2015-12-23

During the first LHC run, the CMS experiment collected tens of Petabytes of collision and simulated data, which need to be distributed among dozens of computing centres with low latency in order to make efficient use of the resources. While the desired level of throughput has been successfully achieved, it is still common to observe transfer workflows that cannot reach full completion in a timely manner due to a small fraction of stuck files which require operator intervention.For this reason, in 2012 the CMS transfer management system, PhEDEx, was instrumented with a monitoring system to measure file transfer latencies, andmore » to predict the completion time for the transfer of a data set. The operators can detect abnormal patterns in transfer latencies while the transfer is still in progress, and monitor the long-term performance of the transfer infrastructure to plan the data placement strategy.Based on the data collected for one year with the latency monitoring system, we present a study on the different factors that contribute to transfer completion time. As case studies, we analyze several typical CMS transfer workflows, such as distribution of collision event data from CERN or upload of simulated event data from the Tier-2 centres to the archival Tier-1 centres. For each workflow, we present the typical patterns of transfer latencies that have been identified with the latency monitor.We identify the areas in PhEDEx where a development effort can reduce the latency, and we show how we are able to detect stuck transfers which need operator intervention. Lastly, we propose a set of metrics to alert about stuck subscriptions and prompt for manual intervention, with the aim of improving transfer completion times.« less

Monitoring data transfer latency in CMS computing operations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonacorsi, Daniele; Diotalevi, Tommaso; Magini, Nicolo

During the first LHC run, the CMS experiment collected tens of Petabytes of collision and simulated data, which need to be distributed among dozens of computing centres with low latency in order to make efficient use of the resources. While the desired level of throughput has been successfully achieved, it is still common to observe transfer workflows that cannot reach full completion in a timely manner due to a small fraction of stuck files which require operator intervention.For this reason, in 2012 the CMS transfer management system, PhEDEx, was instrumented with a monitoring system to measure file transfer latencies, andmore » to predict the completion time for the transfer of a data set. The operators can detect abnormal patterns in transfer latencies while the transfer is still in progress, and monitor the long-term performance of the transfer infrastructure to plan the data placement strategy.Based on the data collected for one year with the latency monitoring system, we present a study on the different factors that contribute to transfer completion time. As case studies, we analyze several typical CMS transfer workflows, such as distribution of collision event data from CERN or upload of simulated event data from the Tier-2 centres to the archival Tier-1 centres. For each workflow, we present the typical patterns of transfer latencies that have been identified with the latency monitor.We identify the areas in PhEDEx where a development effort can reduce the latency, and we show how we are able to detect stuck transfers which need operator intervention. Lastly, we propose a set of metrics to alert about stuck subscriptions and prompt for manual intervention, with the aim of improving transfer completion times.« less

Reassociation of dissociated caseins upon acidification of heated pH-adjusted skim milk.

PubMed

Anema, Skelte G; Li, Yuming

2015-05-01

Milk was heated at different pH (pH 6.5-7.1) and temperatures (20-120 °C/10 min). This resulted in different levels of casein and denatured whey proteins to be distributed between the colloidal and serum phases. The milks were subsequently acidified and the distribution of protein between colloidal and serum was monitored at different pH. On acidification to pH 5.4, the serum phase caseins and denatured whey proteins partially reassociated with the caseins, although a complex behaviour was observed at ∼ pH 5.4 where additional casein dissociation occurred in some samples. At pH below 5.4 the caseins and denatured whey proteins rapidly aggregated. No separate aggregation of κ-casein/denatured whey protein complexes or κ-casein depleted micelles was observed. The earlier gelation of milks heated at higher pH was likely to be due to the destabilisation of the entire milk protein system rather than a preferential aggregation of the serum phase proteins. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biological treatment of habitation waste streams using full scale MABRs

NASA Astrophysics Data System (ADS)

Jackson, William; Barta, Daniel J.; Morse, Audra; Christenson, Dylan; Sevanthi, Ritesh

Recycling waste water is a critical step to support sustainable long term habitation in space. Water is one of the largest contributors to life support requirements. In closed loop life support systems, membrane aerated biological reactors (MABRs) can reduce the dissolved organic carbon (DOC) and ammonia (NH3) concentration as well as decrease the pH, leading to a more stable solution with less potential to support biological growth or promote carryover of unionized ammonia as well as producing a higher quality brine. Over the last three years we have operated 3 full size MABRs ( 120L) treating a habitation type waste stream composed of urine, hygiene, and laundry water. The reactors varied in the specific surface area (260, 200, and 150 m2/m3) available for biofilm growth and gas transfer. The liquid side system was continually monitored for pH, TDS, and DO, and the influent and effluent monitored daily for DOC, TN, NOx, and NH4. The gas side system was continuously monitored for O2, CO2, and N2O in the effluent gas as well as pressure and flow rates. These systems have all demonstrated greater than 90% DOC reductions and ammonium conversion rates of 50-70% over a range of loading rates with effluent pH from 5-7.5. We have evaluated. In addition, to evaluating the impact of loading rates (10-70 l/d) we have also evaluated the impact of forced hibernation, the use of pure O2 on performance, the impact of pressurize operation to prevent de-gassing of N2 and to promote higher O2 transfer and a discontinuous feeding cycle to allow integration with desalination. Our analysis includes quantification of consumables (power and O2), waste products such as CO2 and N2O as well as solids production. Our results support the use of biological reactors to treat habitation waste streams as an alternative to the use of pretreatment and desalination alone.

Combined effects of sea water acidification and copper exposure on the symbiont-bearing foraminifer Amphistegina gibbosa

NASA Astrophysics Data System (ADS)

Marques, Joseane Aparecida; de Barros Marangoni, Laura Fernandes; Bianchini, Adalto

2017-06-01

Coral reefs are threatened by global and local stressors such as ocean acidification and trace metal contamination. Reliable early warning monitoring tools are needed to assess and monitor coral reef health. Symbiont-bearing foraminifers ( Amphistegina gibbosa) were kept under ambient conditions (no sea water acidification and no copper addition) or exposed to combinations of different levels of sea water pH (8.1, 7.8, 7.5 and 7.2) and environmentally relevant concentrations of dissolved copper (measured: 1.0, 1.6, 2.3 and 3.2 µg L-1) in a mesocosm system. After 10- and 25-d exposure, foraminifers were analyzed for holobiont Ca2+-ATPase activity, bleaching, growth and mortality. Enzyme activity was inhibited in foraminifers exposed to pH 7.2 and 3.2 µg L-1 Cu for 25 d. Bleaching frequency was also higher at pH 7.2 combined with copper addition. There was no significant effect of sea water acidification and copper addition on mortality. However, test size was smaller in foraminifers exposed to copper, with a positive interactive effect of sea water acidification. These findings can be explained by the higher availability of free copper ions at lower water pH. This condition would increase Cu competition with Ca2+ for the binding sites on the organism, thus inhibiting Ca2+-ATPase activity and affecting the organism's overall fitness. Findings reported here suggest that key processes in A. gibbosa, such as calcification and photosynthesis, are affected by the combined effect of global (sea water acidification) and local (copper contamination) stressors. Considering the experimental conditions employed (mesocosm system, possible ocean acidification scenarios, low copper concentrations, biomarkers of ecological relevance and chronic exposure), our findings support the use of foraminifera and biomarkers analyzed in the present study as reliable tools to detect and monitor the ecological impacts of multiple stressors in coral reef environments.

Monitoring the Productivity of Coastal Systems Using PH: When Simpler is Better

EPA Science Inventory

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 s...

Monitoring the Productivity of Coastal Systems Using PH: When Simpler is Better (NEERS)

EPA Science Inventory

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 s...

Monitoring the Productivity of Coastal Systems Using PH: When Simpler is Better.

EPA Science Inventory

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 s...

Microbioreactors with microfluidic control and a user-friendly connection to the actuator hardware

NASA Astrophysics Data System (ADS)

Buchenauer, A.; Funke, M.; Büchs, J.; Mokwa, W.; Schnakenberg, U.

2009-07-01

In this study, an array of microbioreactors based on the format of 48-well microtiter plates (MTPs) is presented. The process parameters pH and biomass are monitored online using commercially available optical sensor technology. A microfluidic device dispenses acid or base individually into each well for controlling the pH of fermentations. Fluid volumes from 72 nL to 940 nL can be supplied with valve opening times between 10 ms and 200 ms. One microfluidic device is capable of supplying four wells from two reservoirs. Up to four microfluidic devices can be integrated on the area of a prototype MTP. The devices are fabricated in polydimethylsiloxane (PDMS) using soft lithographic techniques and utilize pneumatically actuated microvalves. During fermentations, the microbioreactor is clamped to an orbital shaker and a temporary pneumatic connection guides the externally controlled pressurized air to the microfluidic device. Finally, fermentations of Escherichia coli in the presence and absence of pH control are carried out in the microbioreactor system over 18 h. During the fermentation the pH of the cultures is continuously monitored by means of optodes. An ammonia solution or phosphoric acid is dispensed to adjust the pH if it differs from the set point of 7.2. In a controlled culture, the pH can be sustained within 7.0 to 7.3 while the pH in an uncontrolled culture ranges between 6.5 and 9.0. This microbioreactor demonstrates the possibility of pH-controlled fermentations in micro-scale. The process control and the user friendly connection to the actuation hardware provide an easy handling comparable to standard MTPs.

Minimized Bolus-Type Wireless Sensor Node with a Built-In Three-Axis Acceleration Meter for Monitoring a Cow’s Rumen Conditions

PubMed Central

Nogami, Hirofumi; Arai, Shozo; Okada, Hironao; Zhan, Lan; Itoh, Toshihiro

2017-01-01

Monitoring rumen conditions in cows is important because a dysfunctional rumen system may cause death. Sub-acute ruminal acidosis (SARA) is a typical disease in cows, and is characterized by repeated periods of low ruminal pH. SARA is regarded as a trigger for rumen atony, rumenitis, and abomasal displacement, which may cause death. In previous studies, rumen conditions were evaluated by wireless sensor nodes with pH measurement capability. The primary advantage of the pH sensor is its ability to continuously measure ruminal pH. However, these sensor nodes have short lifetimes since they are limited by the finite volume of the internal liquid of the reference electrode. Mimicking rumen atony, we attempt to evaluate the rumen condition using wireless sensor nodes with three-axis accelerometers. The theoretical life span of such sensor nodes depends mainly on the transmission frequency of acceleration data and the size of the battery, and the proposed sensor nodes are 30.0 mm in diameter and 70.0 mm in length and have a life span of over 600 days. Using the sensor nodes, we compare the rumen motility of the force transducer measurement with the three-axis accelerometer data. As a result, we can detect discriminative movement of rumen atony. PMID:28346374

Minimized Bolus-Type Wireless Sensor Node with a Built-In Three-Axis Acceleration Meter for Monitoring a Cow's Rumen Conditions.

PubMed

Nogami, Hirofumi; Arai, Shozo; Okada, Hironao; Zhan, Lan; Itoh, Toshihiro

2017-03-27

Monitoring rumen conditions in cows is important because a dysfunctional rumen system may cause death. Sub-acute ruminal acidosis (SARA) is a typical disease in cows, and is characterized by repeated periods of low ruminal pH. SARA is regarded as a trigger for rumen atony, rumenitis, and abomasal displacement, which may cause death. In previous studies, rumen conditions were evaluated by wireless sensor nodes with pH measurement capability. The primary advantage of the pH sensor is its ability to continuously measure ruminal pH. However, these sensor nodes have short lifetimes since they are limited by the finite volume of the internal liquid of the reference electrode. Mimicking rumen atony, we attempt to evaluate the rumen condition using wireless sensor nodes with three-axis accelerometers. The theoretical life span of such sensor nodes depends mainly on the transmission frequency of acceleration data and the size of the battery, and the proposed sensor nodes are 30.0 mm in diameter and 70.0 mm in length and have a life span of over 600 days. Using the sensor nodes, we compare the rumen motility of the force transducer measurement with the three-axis accelerometer data. As a result, we can detect discriminative movement of rumen atony.

Economic comparison of two types of automatic water-quality monitors

USGS Publications Warehouse

Katzenbach, Max

1988-01-01

A comparison of the U.S. Geological Survey's minimonitor system with a self-contained, 'package-sensor' system indicates that the package-sensor system requires less servicing time. The U.S. Geological Survey minimonitor is powered by an external battery and is housed in a weatherproof shelter. This instrument measures temperature, specific conductance, dissolved oxygen, and pH by means of sensors with extension cables having underewater connectors; data are recorder in binary coded decimal form on a 16-channel punched-paper-tape recorder that is housed in a shelter. The packaged-sensor system also measures temperature, specific conductanoe,dissolved oxygen, and pH by means of sensors housed in a package that is submerged in the stream. It has an internal power supply, no moving parts, anf does not require a weatherproof shelter; data are stored in solid-state memory. Minimonitors were installed at four sites in Ohio where U.S. Geological Survey flowthrough monitors already were in opertion. Two package-sensor systems also assigned to each site and alternated every 2 weeks. Detailed records were kept of (1) time involved in operation and maintenace of the systems, and (2) equipment problems during the test period, which lasted from October 1985 through September 1986. Equipment costs were not considered in the economic evaluation. Results of the comparisons show that the packaged-sensor system required less time to install, operate, and maintain than the minimonitor system.

Nano-engineered flexible pH sensor for point-of-care urease detection

NASA Astrophysics Data System (ADS)

Sardarinejad, A.; Maurya, D. K.; Tay, C. Y.; Marshall, B. J.; Alameh, K.

2015-12-01

Accurate pH monitoring is crucial for many applications, such as, water quality monitoring, blood monitoring, chemical and biological analyses, environmental monitoring and clinical diagnostic. The most common technique for pH measurement is based on the use of conventional glass pH electrodes. Glass electrodes have several limitations, such as mechanical fragility, large size, limited shapes and high cost, making them impractical for implementation as Lab-onchips and pH sensor capsules. Various metal oxides, such as RuO2, IrO2, TiO2, SnO2, Ta2O5 and PdO have recently been proposed for the realization of pH sensing electrodes. Specifically, ruthenium oxide exhibits unique properties including thermal stability, excellent corrosion resistance, low hysteresis high sensitivity, and low resistivity. In this paper, we demonstrate the concept of a miniaturized ion selective electrode (ISE) based pH sensor for point-of-care urease monitoring. The sensor comprises a thin film RuO2 on platinum sensing electrode, deposited using E-beam and R.F. magnetron sputtering, in conjunction with an integrated Ag/AgCl reference electrode. The performance and characterization of the developed pH/urea sensors in terms of sensitivity, resolution, reversibility and hysteresis are investigated. Experimental results show a linear potential-versus-urea-concentration response for urea concentrations in the range 0 - 180 mg/ml. Experimental results demonstrate super-Nernstian slopes in the range of 64.33 mV/pH - 73.83 mV/pH for RF sputtered RuO2 on platinum sensing electrode using a 80%:20% Ar:O2 gas ratio. The RuO2 sensor exhibits stable operation and fast dynamic response, making it attractive for in vivo use, wearable and flexible biomedical sensing applications.

Corrosion sensor

DOEpatents

Glass, Robert S.; Clarke, Jr., Willis L.; Ciarlo, Dino R.

1994-01-01

A corrosion sensor array incorporating individual elements for measuring various elements and ions, such as chloride, sulfide, copper, hydrogen (pH), etc. and elements for evaluating the instantaneous corrosion properties of structural materials. The exact combination and number of elements measured or monitored would depend upon the environmental conditions and materials used which are subject to corrosive effects. Such a corrosion monitoring system embedded in or mounted on a structure exposed to the environment would serve as an early warning system for the onset of severe corrosion problems for the structure, thus providing a safety factor as well as economic factors. The sensor array is accessed to an electronics/computational system, which provides a means for data collection and analysis.

Corrosion sensor

DOEpatents

Glass, R.S.; Clarke, W.L. Jr.; Ciarlo, D.R.

1994-04-26

A corrosion sensor array is described incorporating individual elements for measuring various elements and ions, such as chloride, sulfide, copper, hydrogen (pH), etc. and elements for evaluating the instantaneous corrosion properties of structural materials. The exact combination and number of elements measured or monitored would depend upon the environmental conditions and materials used which are subject to corrosive effects. Such a corrosion monitoring system embedded in or mounted on a structure exposed to the environment would serve as an early warning system for the onset of severe corrosion problems for the structure, thus providing a safety factor as well as economic factors. The sensor array is accessed to an electronics/computational system, which provides a means for data collection and analysis. 7 figures.

Inconsistency in the Diagnosis of Functional Heartburn: Usefulness of Prolonged Wireless pH Monitoring in Patients With Proton Pump Inhibitor Refractory Gastroesophageal Reflux Disease

PubMed Central

Penagini, Roberto; Sweis, Rami; Mauro, Aurelio; Domingues, Gerson; Vales, Andres; Sifrim, Daniel

2015-01-01

Background/Aims The diagnosis of functional heartburn is important for management, however it stands on fragile pH monitoring variables, ie, acid exposure time varies from day to day and symptoms are often few or absent. Aim of this study was to investigate consistency of the diagnosis of functional heartburn in subsequent days using prolonged wireless pH monitoring and its impact on patients’ outcome. Methods Fifty proton pump inhibitotor refractory patients (11 male, 48 years [range, 38–57 years]) with a diagnosis of functional heart-burn according to Rome III in the first 24 hours of wireless pH monitoring were reviewed. pH variables were analysed in the following 24-hour periods to determine if tracings were indicative of diagnosis of non-erosive reflux disease (either acid exposure time > 5% or normal acid exposure time and symptom index ≥ 50%). Outcome was assessed by review of hospital files and/or telephone interview. Results Fifteen out of 50 patients had a pathological acid exposure time after the first day of monitoring (10 in the second day and 5 in subsequent days), which changed their diagnosis from functional heartburn to non-erosive reflux disease. Fifty-four percent of non-erosive reflux disease vs 11% of functional heartburn patients (P < 0.003) increased the dose of proton pump inhibitors or underwent fundoplication after the pH test. Outcome was positive in 77% of non-erosive reflux disease vs 43% of functional heartburn patients (P < 0.05). Conclusions One-third of patients classified as functional heartburn at 24-hour pH-monitoring can be re-classified as non-erosive reflux disease after a more prolonged pH recording period. This observation has a positive impact on patients’ management. PMID:25843078

Secondary elements of blood pH variation can influence the effort effectiveness based on adaptive changes within a group of elite athletes.

PubMed

Martin, Ştefan Adrian; Tomescu, Valeriu; Voidăzan, Septimiu

2016-01-01

pH is the direct indicator of the body reaction following the activities performed. Establishing precise correlations between pH and blood biochemical parameters might support the balancing of values during periods of marked physical activity. We conducted a case study in a group of elite rowers. Twelve athletes were included in the study. Monitoring was carried out by collecting biological samples several times a day: in the morning, 80 minutes pre-workout, 12 hours after the last physical effort performed, at two different times, 10 days apart. Determinations were aimed at adapting the reported biochemical parameters depending on the effort performed. The following parameters were monitored: pH, HCO3, pCO2, pO2, BE, SBE, SBC, Ca++, Mg++, LDH, GPT, T-Pro, and Alb. The mean value of pH found in athletes was 7.41±0.024. The value obtained was significantly correlated to biochemical parameters such as BE (2.32±1.79), SBC (1.67±1.45), SBE (2.70±1.75). However, bicarbonate (HCO3) was statistically significantly related with SBE, SBC, SBE, and pO2, but did not present a strong association with the pH value (p=0.094). However, values such as Alb, Ca++, LDH, BE, SBC are related to pH value as a result of variations in the data submitted. The processed data evidence the fact that blood pH, in this case, is significantly influenced by a number of indices that correlate energy system activity, individual adaptation to effort, and the recovery process. The parameters under investigation (SBE, SBC, SBE, CPK, LDH) are associated with pH changes that could confirm the recovery efficiency of the athlete, along with a possible metabolic acidosis/alkalosis.

Noncontact tomography and a pH-sensitive nanocomposite for monitoring osseointegrated prosthesis interfaces

NASA Astrophysics Data System (ADS)

Gupta, Sumit; Loh, Kenneth J.

2017-04-01

The main objective of this research is to develop a noncontact and noninvasive method for monitoring infections at the interface of human tissue and osseointegrated prostheses. The technique used here is centered on the theory of a noncontact permittivity imaging technique known as electrical capacitance tomography (ECT). This work is divided into two main parts. First, an ECT electrical permittivity reconstruction software and hardware system was developed. Second, a carbon nanotube-polyaniline nanocomposite thin film was designed and fabricated such that its electrical permittivity is sensitive to pH stimuli. The dielectric properties of this thin film were characterized as it was exposed to different pH buffer solutions. It is envisioned that osseointegrated implants can be pre-coated with the pH-sensitive nanocomposite prior to implant. When infection occurs and alters the local pH of tissue at the human-prosthesis interface, the dielectric property of the film would change accordingly. Then, ECT can interrogate the cross-section of the human limb and reconstruct its permittivity distribution, revealing localized changes in permittivity due to infection. To validate this concept, a prosthesis phantom was coated with the nanocomposite pH sensor and then immersed in different pH buffer solutions. ECT was conducted, and the results showed that the magnitude and location of subsurface, localized, pH changes could be detected. In general, noncontact tomography coupled with stimuliresponsive thin films could pave way for new modalities of noninvasive human body imaging, in particular, for patients with osseointegrated implants and prostheses.

Regional Monitoring of Acidic Lakes and Streams

EPA Pesticide Factsheets

This asset provides data on the acid-base status of lakes and streams. Key chemical indicators measured include: sulfate, nitrate, ammonium, chloride, Acid Neutralizing Capacity (ANC), pH, base cations, dissolved organic carbon (DOC), total aluminum. TIME and LTM are part of EPA's Environmental Monitoring and Assessment Program (EMAP). Long-term monitoring of the acid-base status (pH, ANC, SO4, NO3, NH4, DOC, base cations, Al) in lakes and streams. Monitoring is conducted in acid sensitive regions of the Eastern U.S.

Supraesophageal Reflux: Correlation of Position and Occurrence of Acid Reflux-Effect of Head-of-Bed Elevation on Supine Reflux.

PubMed

Scott, David R; Simon, Ronald A

2015-01-01

Supraesophageal reflux of gastric contents can contribute to perennial nasopharyngitis, cough, and asthma. However, effective treatment strategies for supraesophageal reflux disease (SERD) remain inadequately defined. The purpose of this study is to assess the prevalence and timing of SERD and to investigate the efficacy of head-of-bed elevation in its treatment. A retrospective chart review of patients seen at Scripps Clinic Division of Allergy, Asthma and Immunology was performed who had undergone overnight nasopharyngeal pH monitoring with a commercially available nasopharyngeal pH-monitoring device, Dx-pH Measurement System from Restech, San Diego, Calif. Subjects with reflux were classified based on the position of reflux as either supine only, upright only, or both supine and upright. In a subset of subjects with supine-only reflux, pH monitoring was compared before and after elevating the head of bed 6 inches. Adequate nasopharyngeal pH-monitoring data were obtained for 235 patients. Reflux was detected in 113 (48%) patients. The pattern of reflux observed was 62 (55%) supine only, 4 (4%) upright only, and 47 (42%) upright and supine. Sequential overnight nasopharyngeal pH monitoring before and after head-of-bed elevation was obtained in 13 individuals with supine-only reflux. Ten subjects demonstrated significant improvement, 8 of whom demonstrated complete resolution of supine reflux with 6 inches of head-of-bed elevation. This study provides new evidence that SERD frequently occurs in the supine position and that 6 inches of head-of-bed elevation is effective in reducing supine SERD. Copyright © 2015 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Fabrication of a Miniature Multi-Parameter Sensor Chip for Water Quality Assessment

PubMed Central

Zhou, Bo; Bian, Chao; Tong, Jianhua; Xia, Shanhong

2017-01-01

Water contamination is a main inducement of human diseases. It is an important step to monitor the water quality in the water distribution system. Due to the features of large size, high cost, and complicated structure of traditional water determination sensors and devices, it is difficult to realize real-time water monitoring on a large scale. In this paper, we present a multi-parameter sensor chip, which is miniature, low-cost, and robust, to detect the pH, conductivity, and temperature of water simultaneously. The sensor chip was fabricated using micro-electro-mechanical system (MEMS) techniques. Iridium oxide film was electrodeposited as the pH-sensing material. The atomic ratio of Ir(III) to Ir(IV) is about 1.38 according to the X-ray photoelectron spectroscopy (XPS) analysis. The pH sensing electrode showed super-Nernstian response (−67.60 mV/pH) and good linearity (R2 = 0.9997), in the range of pH 2.22 to pH 11.81. KCl-agar and epoxy were used as the electrolyte layer and liquid junction for the solid-state reference electrode, respectively, and its potential stability in deionized water was 56 h. The conductivity cell exhibited a linear determination range from 21.43 μS/cm to 1.99 mS/cm, and the electrode constant was 1.566 cm−1. Sensitivity of the temperature sensor was 5.46 Ω/°C. The results indicate that the developed sensor chip has potential application in water quality measurements. PMID:28098824

Understanding the impact of water distribution system conditions on the biodegradation of haloacetic acids and expression of bacterial dehalogenase genes.

PubMed

Behbahani, Mohsen; Lin, Boren; Phares, Tamara L; Seo, Youngwoo

2018-06-05

The objective of this study is to evaluate the influence of water distribution system conditions (pH, total organic carbon, residual chlorine, and phosphate) on haloacetic acids (HAAs) biodegradation. A series of batch microcosm tests were conducted to determine biodegradation kinetics and collected biomass was used for real time quantitative reverse transcription polymerase chain reaction analyses to monitor how these drinking water distribution system conditions affect the relative expression of bacterial dehalogenase genes. It was observed that tested water distribution system conditions affected HAA biodegradation with different removal efficiencies (0-100%). HAA biodegradation was improved in tested samples with TOC (3 mg/L) and pH 8.5 compared to those of TOC (0 mg/L) and pH 7, respectively. However, slight improvement was observed with the increased PO 4 concentration (3.5 mg/L), and the presence of residual chlorine even at low concentration prohibited biodegradation of HAAs. The observed trend in the relative expression of dehII genes was compatible with the HAA biodegradation trend. Overall relative expression ratio of dehII genes was lower at pH 7, phosphate (0.5 mg/L), and TOC (0 mg/L) in comparison with pH 8.5, phosphate (3.5 mg/L), and TOC (3 mg/L) in the same experimental conditions. Copyright © 2018 Elsevier B.V. All rights reserved.

Fluorescence-based biosensor for monitoring of environmental pollutants: From concept to field application.

PubMed

Bidmanova, Sarka; Kotlanova, Marketa; Rataj, Tomas; Damborsky, Jiri; Trtilek, Martin; Prokop, Zbynek

2016-10-15

An advanced optical biosensor was developed based on the enzymatic reaction with halogenated aliphatic hydrocarbons that is accompanied by the fluorescence change of pH indicator. The device is applicable for the detection of halogenated contaminants in water samples with pH ranging from 4 to 10 and temperature ranging from 5 to 60°C. Main advantages of the developed biosensor are small size (60×30×190mm(3)) and portability, which together with short measurement time of 1min belong to crucial attributes of analytical technique useful for routine environmental monitoring. The biosensor was successfully applied for the detection of several important halogenated pollutants under laboratory conditions, e.g., 1,2-dichloroethane, 1,2,3-trichloropropane and γ-hexachlorocyclohexane, with the limits of detection of 2.7, 1.4 and 12.1mgL(-1), respectively. The continuous monitoring was demonstrated by repetitive injection of halogenated compound into measurement solution. Consequently, field trials under environmental settings were performed. The presence of 1,2-dichloroethane (10mgL(-1)) was proved unambiguously on one of three potentially contaminated sites in Czech Republic, and the same contaminant was monitored on contaminated locality in Serbia. Equipped by Global Positioning System, the biosensor was used for creation of a precise map of contamination. Concentrations determined by biosensor and by gas chromatograph coupled with mass spectrometer exhibited the correlation coefficient of 0.92, providing a good confidence for the routine use of the biosensor system in both field screening and monitoring. Copyright © 2015 Elsevier B.V. All rights reserved.

Thermodynamics and kinetics of cyanidin 3-glucoside and caffeine copigments.

PubMed

Limón, Piedad M; Gavara, Raquel; Pina, Fernando

2013-06-05

The multiequilibrium system of reactions of cyanidin 3-glucoside at acidic and mildly acidic pH values was studied in the presence of caffeine as a copigment. The thermodynamic and kinetic constants were determined using the so-called direct and reverse pH jump experiments that were followed by conventional UV-vis spectroscopy or stopped flow coupled to a UV-vis detector, depending on the rate of the monitored process. Compared with that of free anthocyanin, the copigmentation with caffeine extends the domain of the flavylium cation up to less acidic pH values, while in a moderately acidic medium, the quinoidal base becomes more stabilized. As a consequence, the hydration to give the colorless hemiketal is difficult over the entire range of pH values. At pH 1, two adducts were found for the flavylium cation-caffeine interaction, with stoichiometries of 1:1 and 1:2 and association constants of 161 M⁻¹ (K₁) and 21 M⁻¹ (K₂), respectively.

Noninvasive pulmonary artery pressure monitoring by EIT: a model-based feasibility study.

PubMed

Proença, Martin; Braun, Fabian; Solà, Josep; Thiran, Jean-Philippe; Lemay, Mathieu

2017-06-01

Current monitoring modalities for patients with pulmonary hypertension (PH) are limited to invasive solutions. A novel approach for the noninvasive and unsupervised monitoring of pulmonary artery pressure (PAP) in patients with PH was proposed and investigated. The approach was based on the use of electrical impedance tomography (EIT), a noninvasive and safe monitoring technique, and was tested through simulations on a realistic 4D bio-impedance model of the human thorax. Changes in PAP were induced in the model by simulating multiple types of hypertensive conditions. A timing parameter physiologically linked to the PAP via the so-called pulse wave velocity principle was automatically estimated from the EIT data. It was found that changes in PAP could indeed be reliably monitored by EIT, irrespective of the pathophysiological condition that caused them. If confirmed clinically, these findings could open the way for a new generation of noninvasive PAP monitoring solutions for the follow-up of patients with PH.

Guidelines and standard procedures for continuous water-quality monitors: Station operation, record computation, and data reporting

USGS Publications Warehouse

Wagner, Richard J.; Boulger, Robert W.; Oblinger, Carolyn J.; Smith, Brett A.

2006-01-01

The U.S. Geological Survey uses continuous water-quality monitors to assess the quality of the Nation's surface water. A common monitoring-system configuration for water-quality data collection is the four-parameter monitoring system, which collects temperature, specific conductance, dissolved oxygen, and pH data. Such systems also can be configured to measure other properties, such as turbidity or fluorescence. Data from sensors can be used in conjunction with chemical analyses of samples to estimate chemical loads. The sensors that are used to measure water-quality field parameters require careful field observation, cleaning, and calibration procedures, as well as thorough procedures for the computation and publication of final records. This report provides guidelines for site- and monitor-selection considerations; sensor inspection and calibration methods; field procedures; data evaluation, correction, and computation; and record-review and data-reporting processes, which supersede the guidelines presented previously in U.S. Geological Survey Water-Resources Investigations Report WRIR 00-4252. These procedures have evolved over the past three decades, and the process continues to evolve with newer technologies.

An ultrasensitive method of real time pH monitoring with complementary metal oxide semiconductor image sensor.

PubMed

Devadhasan, Jasmine Pramila; Kim, Sanghyo

2015-02-09

CMOS sensors are becoming a powerful tool in the biological and chemical field. In this work, we introduce a new approach on quantifying various pH solutions with a CMOS image sensor. The CMOS image sensor based pH measurement produces high-accuracy analysis, making it a truly portable and user friendly system. pH indicator blended hydrogel matrix was fabricated as a thin film to the accurate color development. A distinct color change of red, green and blue (RGB) develops in the hydrogel film by applying various pH solutions (pH 1-14). The semi-quantitative pH evolution was acquired by visual read out. Further, CMOS image sensor absorbs the RGB color intensity of the film and hue value converted into digital numbers with the aid of an analog-to-digital converter (ADC) to determine the pH ranges of solutions. Chromaticity diagram and Euclidean distance represent the RGB color space and differentiation of pH ranges, respectively. This technique is applicable to sense the various toxic chemicals and chemical vapors by situ sensing. Ultimately, the entire approach can be integrated into smartphone and operable with the user friendly manner. Copyright © 2014 Elsevier B.V. All rights reserved.

Hybrid hard- and soft-modeling of spectrophotometric data for monitoring of ciprofloxacin and its main photodegradation products at different pH values

NASA Astrophysics Data System (ADS)

Razuc, Mariela; Garrido, Mariano; Caro, Yamile S.; Teglia, Carla M.; Goicoechea, Héctor C.; Fernández Band, Beatriz S.

2013-04-01

A simple and fast on line spectrophotometric method combined with a hybrid hard-soft modeling multivariate curve resolution (HS-MCR) was proposed for the monitoring of photodegradation reaction of ciprofloxacin under UV radiation. The studied conditions attempt to emulate the effect of sunlight on these antibiotics that could be eventually present in the environment. The continuous flow system made it possible to study the ciprofloxacin degradation at different pH values almost at real time, avoiding errors that could arise from typical batch monitoring of the reaction. On the base of a concentration profiles obtained by previous pure soft-modeling approach, reaction pathways have been proposed for the parent compound and its photoproducts at different pH values. These kinetic models were used as a constraint in the HS-MCR analysis. The kinetic profiles and the corresponding pure response profile (UV-Vis spectra) of ciprofloxacin and its main degradation products were recovered after the application of HS-MCR analysis to the spectra recorded throughout the reaction. The observed behavior showed a good agreement with the photodegradation studies reported in the bibliography. Accordingly, the photodegradation reaction was studied by high performance liquid chromatography coupled with UV-Vis diode array detector (HPLC-DAD). The spectra recorded during the chromatographic analysis present a good correlation with the ones recovered by UV-Vis/HS-MCR method.

Sensor Access to the Cellular Microenvironment Using the Sensing Cell Culture Flask.

PubMed

Kieninger, Jochen; Tamari, Yaara; Enderle, Barbara; Jobst, Gerhard; Sandvik, Joe A; Pettersen, Erik O; Urban, Gerald A

2018-04-26

The Sensing Cell Culture Flask (SCCF) is a cell culture monitoring system accessing the cellular microenvironment in 2D cell culture using electrochemical microsensors. The system is based on microfabricated sensor chips embedded in standard cell culture flasks. Ideally, the sensor chips could be equipped with any electrochemical sensor. Its transparency allows optical inspection of the cells during measurement. The surface of the sensor chip is in-plane with the flask surface allowing undisturbed cell growth on the sensor chip. A custom developed rack system allows easy usage of multiple flasks in parallel within an incubator. The presented data demonstrates the application of the SCCF with brain tumor (T98G) and breast cancer (T-47D) cells. Amperometric oxygen sensors were used to monitor cellular respiration with different incubation conditions. Cellular acidification was accessed with potentiometric pH sensors using electrodeposited iridium oxide films. The system itself provides the foundation for electrochemical monitoring systems in 3D cell culture.

Automatic aeroponic irrigation system based on Arduino’s platform

NASA Astrophysics Data System (ADS)

Montoya, A. P.; Obando, F. A.; Morales, J. G.; Vargas, G.

2017-06-01

The recirculating hydroponic culture techniques, as aeroponics, has several advantages over traditional agriculture, aimed to improve the efficiently and environmental impact of agriculture. These techniques require continuous monitoring and automation for proper operation. In this work was developed an automatic monitored aeroponic-irrigation system based on the Arduino’s free software platform. Analog and digital sensors for measuring the temperature, flow and level of a nutrient solution in a real greenhouse were implemented. In addition, the pH and electric conductivity of nutritive solutions are monitored using the Arduino’s differential configuration. The sensor network, the acquisition and automation system are managed by two Arduinos modules in master-slave configuration, which communicate one each other wireless by Wi-Fi. Further, data are stored in micro SD memories and the information is loaded on a web page in real time. The developed device brings important agronomic information when is tested with an arugula culture (Eruca sativa Mill). The system also could be employ as an early warning system to prevent irrigation malfunctions.

40 CFR 98.324 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Procedures and Inspection Tracking System Handbook Number: PH-08-V-1, January 1, 2008 (incorporated by... paragraphs (d)(1) through (d)(2) of this section. (1) ASTM D1945-03, Standard Test Method for Analysis of... Reformed Gas by Gas Chromatography; ASTM D4891-89 (Reapproved 2006), Standard Test Method for Heating Value...

40 CFR 98.324 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Procedures and Inspection Tracking System Handbook Number: PH-08-V-1, January 1, 2008 (incorporated by... paragraphs (d)(1) through (d)(2) of this section. (1) ASTM D1945-03, Standard Test Method for Analysis of... Reformed Gas by Gas Chromatography; ASTM D4891-89 (Reapproved 2006), Standard Test Method for Heating Value...

40 CFR 98.324 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Procedures and Inspection Tracking System Handbook Number: PH-08-V-1, January 1, 2008 (incorporated by... ASTM D1945-03, Standard Test Method for Analysis of Natural Gas by Gas Chromatography; ASTM D1946-90... (Reapproved 2006), Standard Test Method for Heating Value of Gases in Natural Gas Range by Stoichiometric...

40 CFR 63.9804 - What are my monitoring system installation, operation, and maintenance requirements?

Code of Federal Regulations, 2014 CFR

2014-07-01

... accuracy that is traceable to National Institute of Standards and Technology (NIST) standards. (ii) The... section. (i) Perform a single-point calibration using an NIST-certified buffer solution that is accurate... include a redundant pH sensor, perform a single point calibration using an NIST-certified buffer solution...

40 CFR 63.9804 - What are my monitoring system installation, operation, and maintenance requirements?

Code of Federal Regulations, 2013 CFR

2013-07-01

... accuracy that is traceable to National Institute of Standards and Technology (NIST) standards. (ii) The... section. (i) Perform a single-point calibration using an NIST-certified buffer solution that is accurate... include a redundant pH sensor, perform a single point calibration using an NIST-certified buffer solution...

Imaging intracellular pH in live cells with a genetically encoded red fluorescent protein sensor.

PubMed

Tantama, Mathew; Hung, Yin Pun; Yellen, Gary

2011-07-06

Intracellular pH affects protein structure and function, and proton gradients underlie the function of organelles such as lysosomes and mitochondria. We engineered a genetically encoded pH sensor by mutagenesis of the red fluorescent protein mKeima, providing a new tool to image intracellular pH in live cells. This sensor, named pHRed, is the first ratiometric, single-protein red fluorescent sensor of pH. Fluorescence emission of pHRed peaks at 610 nm while exhibiting dual excitation peaks at 440 and 585 nm that can be used for ratiometric imaging. The intensity ratio responds with an apparent pK(a) of 6.6 and a >10-fold dynamic range. Furthermore, pHRed has a pH-responsive fluorescence lifetime that changes by ~0.4 ns over physiological pH values and can be monitored with single-wavelength two-photon excitation. After characterizing the sensor, we tested pHRed's ability to monitor intracellular pH by imaging energy-dependent changes in cytosolic and mitochondrial pH.

Photoactive and self-sensing P3HT-based thin films for strain and corrosion monitoring

NASA Astrophysics Data System (ADS)

Ryu, Donghyeon; Loh, Kenneth J.

2014-03-01

Structural systems deteriorate due to excessive deformation and corrosive environments. If damage is left undetected, they can propagate to cause sudden collapse. However, one of the main difficulties of monitoring damage progression is that, for example, excessive/plastic deformation and corrosion are drastically different physical processes. Strain is a mechanical phenomenon, whereas corrosion is a complex electrochemical process. The current strategy for structural health monitoring (SHM) is to use either different types of sensors or to employ system identification for quantifying overall changes to the structure. In this study, an alternative SHM paradigm is proposed in that a single, multifunctional material would be able to selectively sense different but simultaneously occurring structural damage. In particular, a photoactive and self-sensing thin film was developed for monitoring strain and corrosion. Another unique aspect was that the films were self-sensing and did not depend on external electrical energy for operations. First, the thin films were fabricated using photoactive poly(3-hexylthiophene) (P3HT) and other functional polymers using spin-coating and layerby- layer assembly. Second, the fabricated thin films were interrogated using an ultraviolet-visible (UV-Vis) spectrophotometer for quantifying their optical response to applied external stimuli, such as strain and exposure to pH buffer solutions. Lastly, the multifunctional thin films were tested and validated for strain and pH sensing. Interrogation of these separate responses was achieved by illuminating the thin films different wavelengths of light and then measuring the corresponding electrical current generated.

Neural-fuzzy control system application for monitoring process response and control of anaerobic hybrid reactor in wastewater treatment and biogas production.

PubMed

Waewsak, Chaiwat; Nopharatana, Annop; Chaiprasert, Pawinee

2010-01-01

Based on the developed neural-fuzzy control system for anaerobic hybrid reactor (AHR) in wastewater treatment and biogas production, the neural network with backpropagation algorithm for prediction of the variables pH, alkalinity (Alk) and total volatile acids (TVA) at present day time t was used as input data for the fuzzy logic to calculate the influent feed flow rate that was applied to control and monitor the process response at different operations in the initial, overload influent feeding and the recovery phases. In all three phases, this neural-fuzzy control system showed great potential to control AHR in high stability and performance and quick response. Although in the overloading operation phase II with two fold calculating influent flow rate together with a two fold organic loading rate (OLR), this control system had rapid response and was sensitive to the intended overload. When the influent feeding rate was followed by the calculation of control system in the initial operation phase I and the recovery operation phase III, it was found that the neural-fuzzy control system application was capable of controlling the AHR in a good manner with the pH close to 7, TVA/Alk < 0.4 and COD removal > 80% with biogas and methane yields at 0.45 and 0.30 m3/kg COD removed.

Construction and Setup of a Bench-scale Algal Photosynthetic Bioreactor with Temperature, Light, and pH Monitoring for Kinetic Growth Tests.

PubMed

Karam, Amanda L; McMillan, Catherine C; Lai, Yi-Chun; de Los Reyes, Francis L; Sederoff, Heike W; Grunden, Amy M; Ranjithan, Ranji S; Levis, James W; Ducoste, Joel J

2017-06-14

The optimal design and operation of photosynthetic bioreactors (PBRs) for microalgal cultivation is essential for improving the environmental and economic performance of microalgae-based biofuel production. Models that estimate microalgal growth under different conditions can help to optimize PBR design and operation. To be effective, the growth parameters used in these models must be accurately determined. Algal growth experiments are often constrained by the dynamic nature of the culture environment, and control systems are needed to accurately determine the kinetic parameters. The first step in setting up a controlled batch experiment is live data acquisition and monitoring. This protocol outlines a process for the assembly and operation of a bench-scale photosynthetic bioreactor that can be used to conduct microalgal growth experiments. This protocol describes how to size and assemble a flat-plate, bench-scale PBR from acrylic. It also details how to configure a PBR with continuous pH, light, and temperature monitoring using a data acquisition and control unit, analog sensors, and open-source data acquisition software.

Construction and Setup of a Bench-scale Algal Photosynthetic Bioreactor with Temperature, Light, and pH Monitoring for Kinetic Growth Tests

PubMed Central

Karam, Amanda L.; McMillan, Catherine C.; Lai, Yi-Chun; de los Reyes, Francis L.; Sederoff, Heike W.; Grunden, Amy M.; Ranjithan, Ranji S.; Levis, James W.; Ducoste, Joel J.

2017-01-01

The optimal design and operation of photosynthetic bioreactors (PBRs) for microalgal cultivation is essential for improving the environmental and economic performance of microalgae-based biofuel production. Models that estimate microalgal growth under different conditions can help to optimize PBR design and operation. To be effective, the growth parameters used in these models must be accurately determined. Algal growth experiments are often constrained by the dynamic nature of the culture environment, and control systems are needed to accurately determine the kinetic parameters. The first step in setting up a controlled batch experiment is live data acquisition and monitoring. This protocol outlines a process for the assembly and operation of a bench-scale photosynthetic bioreactor that can be used to conduct microalgal growth experiments. This protocol describes how to size and assemble a flat-plate, bench-scale PBR from acrylic. It also details how to configure a PBR with continuous pH, light, and temperature monitoring using a data acquisition and control unit, analog sensors, and open-source data acquisition software. PMID:28654054

[Application of continuous intra-arterial blood gas monitoring system "Paratrend 7" for pulmonary lavage of a patient with alveolar proteinosis].

PubMed

Harigae, M; Hirose, Y; Gamo, M; Hirose, M; Fujiwara, C; Matsuo, K

1999-03-01

We applied a continuous intra-arterial blood gas monitoring system (Paratrend 7) to a patient with pulmonary alveolar proteinosis during pulmonary lavage. Lavage was performed under general anesthesia with one lung ventilation. We inserted the sensor of Patatrend 7 through a 20 G catheter into the radial artery, and monitored pH, PaCO2 and PaO2 continuously throughout the procedure. SpO2 and EtCO2 were also monitored. Saline 1000-1500 ml was instilled and drained repeatedly by volume limited methods. PaO2 values by Paratrend 7 increased during instillation and decreased during drainage of the irrigating fluid. In contrast, PaCO2 value by Paratrend 7 decreased slightly during instillation and increased during drainage. The change of SpO2 was almost the same as that by Paratrend 7, but the response time of pulse oxymetry was a little quicker than Paratrend 7. During the lavage procedure, respiratory and circulatory condition changed very rapidly, and it is necessary to monitor blood gas change intensively. Paratrend 7 is useful as a perioperative monitoring system, but pulse oxymetry might be sufficient during pulmonary lavage considering its cost.

Space Biosensor Systems: Implications for Technology Transfer

NASA Technical Reports Server (NTRS)

Hines, J. W.; Somps, C. J.; Madou, M.; Imprescia, Clifford C. (Technical Monitor)

1997-01-01

To meet the need for continuous, automated monitoring of animal subjects, including; humans, during space flight, NASA is developing advanced physiologic sensor and biotelemetry system technologies. The ability to continuously track basic physiological parameters, such as heart rate, blood pH, and body temperature, in untethered subjects in space is a challenging task. At NASA's Ames Research Center, where a key focus is gravitational biology research, engineers have teamed with life scientists to develop wireless sensor systems for automated physiologic monitoring of animal models as small as the rat. This technology is also being adapted, in collaboration with medical professionals, to meet human clinical monitoring needs both in space and on the ground. Thus, these advanced monitoring technologies have important dual-use functions; they meet space flight data collection requirements and constraints, while concurrently addressing a number of monitoring and data acquisition challenges on the ground in areas of clinical monitoring and biomedical research. Additional applications for these and related technologies are being sought and additional partnerships established that enhance development efforts, reduce costs and facilitate technology infusion between the public and private sectors. This paper describes technology transfer and co-development projects that have evolved out of NASA's miniaturized, implantable chemical sensor development efforts.

[Pulmonary hemorrhage in patients with systemic lupus erythematosus. Clinical manifestations and prognosis].

PubMed

Finucci Curi, Pablo; Pierrestegui, Matilde; Ortiz, Alberto; Ceccato, Federico; Paira, Sergio

2015-11-06

Pulmonary hemorrhage (PH) in systemic lupus erythematosus (SLE) is a rare but potentially fatal complication that occurs most frequently in the context of active lupus with involvement of other organs. The objective of this study is to report the clinical features and prognosis of patients with SLE who had PH. Patients with SLE (1982 American College of Rheumatology criteria) and PH under monitoring between June 1999 and November 2011 were studied. Demographic, clinical, laboratory, treatment and prognosis data related to PH were analyzed. Eleven patients with SLE developed 14 episodes of PH. PH was the first manifestation of SLE in 2 patients. The most frequent symptoms and clinical signs were dyspnea, fever and cough, which occurred in 12 (85%), 11 (77%) and 7 (50%) patients, respectively. Hemoptysis was also observed in 5 (35%) episodes, tachycardia in 2 (14%), pallor in one (7%) and chest pain in one (7%). All patients had other concomitant organ involvement, and were treated with glucocorticoids. In addition, intravenous cyclophosphamide was indicated in 12 episodes and plasma exchange in 4. Overall mortality was 64%. Factors associated with mortality were infection, mechanical ventilation and dialysis. PH continues to be a rare and severe complication of SLE. Its suspected presence forces us to quickly study these patients, since early diagnosis and aggressive treatment have been shown to improve survival in them. Copyright © 2014 Elsevier España, S.L.U. All rights reserved.

Synthesis and characterization of a multifunctional gold-doxorubicin nanoparticle system for pH triggered intracellular anticancer drug release.

PubMed

Khutale, Ganesh V; Casey, Alan

2017-10-01

A nanoparticle drug carrier system has been developed to alter the cellular uptake and chemotherapeutic performance of an available chemotherapeutic drug. The system comprises of a multifunctional gold nanoparticle based drug delivery system (Au-PEG-PAMAM-DOX) as a novel platform for intracellular delivery of doxorubicin (DOX). Spherical gold nanoparticles were synthesized by a gold chloride reduction, stabilized with thiolated polyethylene glycol (PEG) and then covalently coupled with a polyamidoamine (PAMAM) G4 dendrimer. Further, conjugation of an anti-cancer drug doxorubicin to the dendrimer via amide bond resulted in Au-PEG-PAMAM-DOX drug delivery system. Acellular drug release studies proved that DOX released from Au-PEG-PAMAM-DOX at physiological pH was negligible but it was significantly increased at a weak acidic milieu. The intracellular drug release was monitored with confocal laser scanning microscopy analysis. In vitro viability studies showed an increase in the associated doxorubicin cytotoxicity not attributed to carrier components indicating the efficiency of the doxorubicin was improved, upon conjugation to the nano system. As such it is postulated that the developed pH triggered multifunctional doxorubicin-gold nanoparticle system, could lead to a promising platform for intracellular delivery of variety of anticancer drugs. Copyright © 2017 Elsevier B.V. All rights reserved.

Tattoo-based potentiometric ion-selective sensors for epidermal pH monitoring.

PubMed

Bandodkar, Amay J; Hung, Vinci W S; Jia, Wenzhao; Valdés-Ramírez, Gabriela; Windmiller, Joshua R; Martinez, Alexandra G; Ramírez, Julian; Chan, Garrett; Kerman, Kagan; Wang, Joseph

2013-01-07

This article presents the fabrication and characterization of novel tattoo-based solid-contact ion-selective electrodes (ISEs) for non-invasive potentiometric monitoring of epidermal pH levels. The new fabrication approach combines commercially available temporary transfer tattoo paper with conventional screen printing and solid-contact polymer ISE methodologies. The resulting tattoo-based potentiometric sensors exhibit rapid and sensitive response to a wide range of pH changes with no carry-over effects. Furthermore, the tattoo ISE sensors endure repetitive mechanical deformation, which is a key requirement of wearable and epidermal sensors. The flexible and conformal nature of the tattoo sensors enable them to be mounted on nearly any exposed skin surface for real-time pH monitoring of the human perspiration, as illustrated from the response during a strenuous physical activity. The resulting tattoo-based ISE sensors offer considerable promise as wearable potentiometric sensors suitable for diverse applications.

Monitoring pH and electric conductivity in an EBPR sequencing batch reactor.

PubMed

Serralta, J; Borrás, L; Blanco, C; Barat, R; Seco, A

2004-01-01

This paper presents laboratory-scale experimentation carried out to study enhanced biological phosphorus removal. Two anaerobic aerobic (A/O) sequencing batch reactors (SBR) have been operated during more than one year to investigate the information provided by monitoring pH and electric conductivity under stationary and transient conditions. Continuous measurements of these parameters allow detecting the end of anaerobic phosphorus release, of aerobic phosphorus uptake and of initial denitrification, as well as incomplete acetic acid uptake. These results suggest the possibility of using pH and electric conductivity as control parameters to determine the length of both anaerobic and aerobic phases in an A/O SBR. More valuable information provided by monitoring pH and electric conductivity is the relation between the amount of phosphorus released and the conductivity increase observed during the anaerobic stages and which group of bacteria (heterotrophic or polyphosphate accumulating) is carrying out the denitrification process.

Optical sensing system based on wireless paired emitter detector diode device and ionogels for lab-on-a-disc water quality analysis.

PubMed

Czugala, Monika; Gorkin, Robert; Phelan, Thomas; Gaughran, Jennifer; Curto, Vincenzo Fabio; Ducrée, Jens; Diamond, Dermot; Benito-Lopez, Fernando

2012-12-07

This work describes the first use of a wireless paired emitter detector diode device (PEDD) as an optical sensor for water quality monitoring in a lab-on-a-disc device. The microfluidic platform, based on an ionogel sensing area combined with a low-cost optical sensor, is applied for quantitative pH and qualitative turbidity monitoring of water samples at point-of-need. The autonomous capabilities of the PEDD system, combined with the portability and wireless communication of the full device, provide the flexibility needed for on-site water testing. Water samples from local fresh and brackish sources were successfully analysed using the device, showing very good correlation with standard bench-top systems.

Sensing and adaptation to low pH mediated by inducible amino acid decarboxylases in Salmonella.

PubMed

Viala, Julie P M; Méresse, Stéphane; Pocachard, Bérengère; Guilhon, Aude-Agnès; Aussel, Laurent; Barras, Frédéric

2011-01-01

During the course of infection, Salmonella enterica serovar Typhimurium must successively survive the harsh acid stress of the stomach and multiply into a mild acidic compartment within macrophages. Inducible amino acid decarboxylases are known to promote adaptation to acidic environments. Three low pH inducible amino acid decarboxylases were annotated in the genome of S. Typhimurium, AdiA, CadA and SpeF, which are specific for arginine, lysine and ornithine, respectively. In this study, we characterized and compared the contributions of those enzymes in response to acidic challenges. Individual mutants as well as a strain deleted for the three genes were tested for their ability (i) to survive an extreme acid shock, (ii) to grow at mild acidic pH and (iii) to infect the mouse animal model. We showed that the lysine decarboxylase CadA had the broadest range of activity since it both had the capacity to promote survival at pH 2.3 and growth at pH 4.5. The arginine decarboxylase AdiA was the most performant in protecting S. Typhimurium from a shock at pH 2.3 and the ornithine decarboxylase SpeF conferred the best growth advantage under anaerobiosis conditions at pH 4.5. We developed a GFP-based gene reporter to monitor the pH of the environment as perceived by S. Typhimurium. Results showed that activities of the lysine and ornithine decarboxylases at mild acidic pH did modify the local surrounding of S. Typhimurium both in culture medium and in macrophages. Finally, we tested the contribution of decarboxylases to virulence and found that these enzymes were dispensable for S. Typhimurium virulence during systemic infection. In the light of this result, we examined the genomes of Salmonella spp. normally responsible of systemic infection and observed that the genes encoding these enzymes were not well conserved, supporting the idea that these enzymes may be not required during systemic infection.

Continuous haematic pH monitoring in extracorporeal circulation using a disposable florescence sensing element

NASA Astrophysics Data System (ADS)

Ferrari, Luca; Rovati, Luigi; Fabbri, Paola; Pilati, Francesco

2013-02-01

During extracorporeal circulation (ECC), blood is periodically sampled and analyzed to maintain the blood-gas status of the patient within acceptable limits. This protocol has well-known drawbacks that may be overcome by continuous monitoring. We present the characterization of a new pH sensor for continuous monitoring in ECC. This monitoring device includes a disposable fluorescence-sensing element directly in contact with the blood, whose fluorescence intensity is strictly related to the pH of the blood. In vitro experiments show no significant difference between the blood gas analyzer values and the sensor readings; after proper calibration, it gives a correlation of R>0.9887, and measuring errors were lower than the 3% of the pH range of interest (RoI) with respect to a commercial blood gas analyzer. This performance has been confirmed also by simulating a moderate ipothermia condition, i.e., blood temperature 32°C, frequently used in cardiac surgery. In ex vivo experiments, performed with animal models, the sensor is continuously operated in an extracorporeal undiluted blood stream for a maximum of 11 h. It gives a correlation of R>0.9431, and a measuring error lower than the 3% of the pH RoI with respect to laboratory techniques.

Continuous haematic pH monitoring in extracorporeal circulation using a disposable florescence sensing element.

PubMed

Ferrari, Luca; Rovati, Luigi; Fabbri, Paola; Pilati, Francesco

2013-02-01

During extracorporeal circulation (ECC), blood is periodically sampled and analyzed to maintain the blood-gas status of the patient within acceptable limits. This protocol has well-known drawbacks that may be overcome by continuous monitoring. We present the characterization of a new pH sensor for continuous monitoring in ECC. This monitoring device includes a disposable fluorescence-sensing element directly in contact with the blood, whose fluorescence intensity is strictly related to the pH of the blood. In vitro experiments show no significant difference between the blood gas analyzer values and the sensor readings; after proper calibration, it gives a correlation of R>0.9887, and measuring errors were lower than the 3% of the pH range of interest (RoI) with respect to a commercial blood gas analyzer. This performance has been confirmed also by simulating a moderate ipothermia condition, i.e., blood temperature 32°C, frequently used in cardiac surgery. In ex vivo experiments, performed with animal models, the sensor is continuously operated in an extracorporeal undiluted blood stream for a maximum of 11 h. It gives a correlation of R>0.9431, and a measuring error lower than the 3% of the pH RoI with respect to laboratory techniques.

Temporal Dynamics of In-Field Bioreactor Populations Reflect the Groundwater System and Respond Predictably to Perturbation.

PubMed

King, Andrew J; Preheim, Sarah P; Bailey, Kathryn L; Robeson, Michael S; Roy Chowdhury, Taniya; Crable, Bryan R; Hurt, Richard A; Mehlhorn, Tonia; Lowe, Kenneth A; Phelps, Tommy J; Palumbo, Anthony V; Brandt, Craig C; Brown, Steven D; Podar, Mircea; Zhang, Ping; Lancaster, W Andrew; Poole, Farris; Watson, David B; W Fields, Matthew; Chandonia, John-Marc; Alm, Eric J; Zhou, Jizhong; Adams, Michael W W; Hazen, Terry C; Arkin, Adam P; Elias, Dwayne A

2017-03-07

Temporal variability complicates testing the influences of environmental variability on microbial community structure and thus function. An in-field bioreactor system was developed to assess oxic versus anoxic manipulations on in situ groundwater communities. Each sample was sequenced (16S SSU rRNA genes, average 10,000 reads), and biogeochemical parameters are monitored by quantifying 53 metals, 12 organic acids, 14 anions, and 3 sugars. Changes in dissolved oxygen (DO), pH, and other variables were similar across bioreactors. Sequencing revealed a complex community that fluctuated in-step with the groundwater community and responded to DO. This also directly influenced the pH, and so the biotic impacts of DO and pH shifts are correlated. A null model demonstrated that bioreactor communities were driven in part not only by experimental conditions but also by stochastic variability and did not accurately capture alterations in diversity during perturbations. We identified two groups of abundant OTUs important to this system; one was abundant in high DO and pH and contained heterotrophs and oxidizers of iron, nitrite, and ammonium, whereas the other was abundant in low DO with the capability to reduce nitrate. In-field bioreactors are a powerful tool for capturing natural microbial community responses to alterations in geochemical factors beyond the bulk phase.

Temporal Dynamics of In-Field Bioreactor Populations Reflect the Groundwater System and Respond Predictably to Perturbation

DOE PAGES

King, Andrew J.; Preheim, Sarah P.; Bailey, Kathryn L.; ...

2017-01-23

Temporal variability complicates testing the influences of environmental variability on microbial community structure and thus function. An in-field bioreactor system was developed to assess oxic versus anoxic manipulations on in-situ groundwater communities. Each sample was sequenced (16S SSU rRNA genes, average 10,000 reads) and biogeochemical parameters monitored by quantifying 53 metals, 12 organic acids, 14 anions and 3 sugars. Changes in dissolved oxygen (DO), pH, and other variables were similar across bioreactors. Sequencing revealed a complex community that fluctuated in-step with the groundwater community, and responded to DO. This also directly influenced the pH and so the biotic impacts ofmore » DO and pH shifts are correlated. A null model demonstrated that bioreactor communities were driven in part by experimental conditions but also by stochastic variability and did not accurately capture alterations in diversity during perturbations. We identified two groups of abundant OTUs important to this system; one was abundant in high DO and pH and contained heterotrophs and oxidizers of iron, nitrite, and ammonium, whereas the other was abundant in low DO with the capability to reduce nitrate. In-field bioreactors are a powerful tool for capturing natural microbial community responses to alterations in geochemical factors beyond the bulk phase.« less

Temporal Dynamics of In-Field Bioreactor Populations Reflect the Groundwater System and Respond Predictably to Perturbation

DOE Office of Scientific and Technical Information (OSTI.GOV)

King, Andrew J.; Preheim, Sarah P.; Bailey, Kathryn L.

Temporal variability complicates testing the influences of environmental variability on microbial community structure and thus function. An in-field bioreactor system was developed to assess oxic versus anoxic manipulations on in-situ groundwater communities. Each sample was sequenced (16S SSU rRNA genes, average 10,000 reads) and biogeochemical parameters monitored by quantifying 53 metals, 12 organic acids, 14 anions and 3 sugars. Changes in dissolved oxygen (DO), pH, and other variables were similar across bioreactors. Sequencing revealed a complex community that fluctuated in-step with the groundwater community, and responded to DO. This also directly influenced the pH and so the biotic impacts ofmore » DO and pH shifts are correlated. A null model demonstrated that bioreactor communities were driven in part by experimental conditions but also by stochastic variability and did not accurately capture alterations in diversity during perturbations. We identified two groups of abundant OTUs important to this system; one was abundant in high DO and pH and contained heterotrophs and oxidizers of iron, nitrite, and ammonium, whereas the other was abundant in low DO with the capability to reduce nitrate. In-field bioreactors are a powerful tool for capturing natural microbial community responses to alterations in geochemical factors beyond the bulk phase.« less

Evaluation of gastro-oesophageal reflux disease in wheezy infants using 24-h oesophageal combined impedance and pH monitoring.

PubMed

Abdallah, Ahmed; El-Desoky, Tarek; Fathi, Khalid; Fawzi Elkashef, Wagdi; Zaki, Ahmed

2017-06-01

Gastro-oesophageal reflux disease (GERD) is incriminated as a cause of non-asthmatic infantile wheeze. To date, no diagnostic test is considered standard for GERD-related airway reflux diagnosis. Oesophageal combined multiple channel intraluminal impedance and pH (MII-pH) monitoring is proposed to be a sensitive tool for evaluation of all GERD including infantile wheeze. We aimed to determine the GERD prevalence amongst wheezy infants in the first year of life using combined MII-pH versus pH monitoring alone and evaluate the sensitivity and specificity of objective MII-pH monitoring parameters in GERD-associated infantile wheeze diagnosis compared to those of lipid-laden macrophage index (LLMI). Thirty-eight wheezy infants below 1year of age were evaluated for GERD using oesophageal combined MII-pH monitoring and LLMI. Totally, 60.5% of cases had abnormal MII-pH; only 7.9% of them had abnormal pH monitoring. LLMI was significantly higher in wheezy infants with abnormal MII-pH than infants with normal MII-pH monitoring (112±88 versus 70±48; P=0.036). The current definitions of abnormal MII-pH study, reflux index≥10% and distal reflux episodes≥100, had low sensitivity (23%) but high specificity (100% and 96%, respectively) in GERD-related aspiration diagnosis defined by LLMI≥100. Using ROC curves, bolus contact time≥2.4% and proximal reflux episodes≥46 had 61% and 54% sensitivity and 64% and 76% specificity, respectively, in GERD-related aspiration diagnosis. Combined MII-pH is superior to pH monitoring in reflux-associated infantile wheeze diagnosis. Objective data including proximal reflux episodes and bolus contact time should be combined with the current parameters used in reflux-associated infantile wheeze diagnosis. Copyright © 2017 Pan-Arab Association of Gastroenterology. Published by Elsevier B.V. All rights reserved.

Sub-micron opto-chemical probes for studying living neurons

NASA Astrophysics Data System (ADS)

Hossein-Zadeh, M.; Delgado, J.; Schweizer, F.; Lieberman, R.

2017-02-01

We have fabricated sub-micron opto-chemical probes for pH, oxygen and calcium monitoring and demonstrated their application in intracellular and extracellular monitoring of neurons (cortical neuronal cultures and acute hippocampal slices). Using these probes, we have measured extracellular pH in the stratum radiatum of the CA1 region of mouse hippocampus upon stimulation of presynaptic Schaffer collateral axons. Synaptic transmission was monitored using standard electrophysiological techniques. We find that the local pH transiently changes in response to synaptic stimulation. In addition, the geometry of the functionalized region on the probe combined with high sensitivity imaging enables simultaneous monitoring of spatially adjacent but distinct compartments. As proof of concept we impaled cultured neurons with the probe measured calcium and pH inside as well as directly outside of neurons as we changed the pH and calcium concentration in the physiological solution in the perfusion chamber. As such these probes can be used to study the impact of the environment on both cellular and extra-cellular space. Additionally as the chemical properties of the surrounding medium can be controlled and monitored with high precision, these probes enable differential measurement of the target parameter referenced to a stable bath. This approach eliminates the uncertainties associated with non-chemical fluctuations in the fluorescent emission and result in a self-calibrated opto-chemical probe. We have also demonstrated multifunctional probes that are capable of measuring up to three parameters in the extracellular space in brain slices.

Immobilization of pH-sensitive CdTe Quantum Dots in a Poly(acrylate) Hydrogel for Microfluidic Applications

NASA Astrophysics Data System (ADS)

Franke, M.; Leubner, S.; Dubavik, A.; George, A.; Savchenko, T.; Pini, C.; Frank, P.; Melnikau, D.; Rakovich, Y.; Gaponik, N.; Eychmüller, A.; Richter, A.

2017-04-01

Microfluidic devices present the basis of modern life sciences and chemical information processing. To control the flow and to allow optical readout, a reliable sensor material that can be easily utilized for microfluidic systems is in demand. Here, we present a new optical readout system for pH sensing based on pH sensitive, photoluminescent glutathione capped cadmium telluride quantum dots that are covalently immobilized in a poly(acrylate) hydrogel. For an applicable pH sensing the generated hybrid material is integrated in a microfluidic sensor chip setup. The hybrid material not only allows in situ readout, but also possesses valve properties due to the swelling behavior of the poly(acrylate) hydrogel. In this work, the swelling property of the hybrid material is utilized in a microfluidic valve seat, where a valve opening process is demonstrated by a fluid flow change and in situ monitored by photoluminescence quenching. This discrete photoluminescence detection (ON/OFF) of the fluid flow change (OFF/ON) enables upcoming chemical information processing.

Patients with established gastro-esophageal reflux disease might benefit from Helicobacter pylori eradication

PubMed Central

Moschos, John M.; Kouklakis, George; Vradelis, Stergios; Zezos, Petros; Pitiakoudis, Michael; Chatzopoulos, Dimitrios; Zavos, Christos; Kountouras, Jannis

2014-01-01

Background The aim of this study was to investigate the effect of Helicobacter pylori (H. pylori) eradication in selected H. pylori-positive patients with a primary diagnosis of gastro-esophageal reflux disease (GERD) by using the 3-h postprandial esophageal pH monitoring. Methods We recruited patients with erosive esophagitis at endoscopy and H. pylori infection at histology, successfully cured following eradication therapy; the selected H. pylori-positive patients had weekly reflux symptoms for at least six months and endoscopically established Grade A or B esophagitis. Twenty-nine eligible patients were initially subjected to esophageal manometry and ambulatory 3-h postprandial esophageal pH monitoring. All patients received H. pylori triple eradication therapy accompanied by successful H. pylori eradication. After successful eradication of H. pylori (confirmed by 13C urea breath test), a second manometry and 3-h postprandial esophageal pH monitoring were introduced to assess the results of eradication therapy, after a 3-month post-treatment period. Results All 29 selected H. pylori-positive patients became negative due to successful H. pylori eradication, evaluated by 13C urea breath test after a 4-week post-treatment period. Post-eradication, 62.1% patients showed similar manometric pattern at baseline; 17.2% showed improvement; 17.2% normalization; and 3.4% deterioration of the manometric patterns. The DeMeester symptom scoring in the 3-h postprandial ambulatory esophageal pH monitoring was improved after eradication of H. pylori (median 47.47 vs. 22.00, Wilcoxon’s singed rank; P=0.016). On comparing the pH monitoring studies for each patient at baseline and post-eradication period, 82.8% patients showed improvement and 17.2% deterioration of the DeMeester score. Conclusion By using 3-h postprandial esophageal pH monitoring, this study showed, for the first time, that H. pylori eradication may positively influence GERD symptoms. Large-scale controlled relative studies are warranted to confirm these findings. PMID:25330805

Patients with established gastro-esophageal reflux disease might benefit from Helicobacter pylori eradication.

PubMed

Moschos, John M; Kouklakis, George; Vradelis, Stergios; Zezos, Petros; Pitiakoudis, Michael; Chatzopoulos, Dimitrios; Zavos, Christos; Kountouras, Jannis

2014-01-01

The aim of this study was to investigate the effect of Helicobacter pylori ( H. pylori ) eradication in selected H. pylori -positive patients with a primary diagnosis of gastro-esophageal reflux disease (GERD) by using the 3-h postprandial esophageal pH monitoring. We recruited patients with erosive esophagitis at endoscopy and H. pylori infection at histology, successfully cured following eradication therapy; the selected H. pylori -positive patients had weekly reflux symptoms for at least six months and endoscopically established Grade A or B esophagitis. Twenty-nine eligible patients were initially subjected to esophageal manometry and ambulatory 3-h postprandial esophageal pH monitoring. All patients received H. pylori triple eradication therapy accompanied by successful H. pylori eradication. After successful eradication of H. pylori (confirmed by 13 C urea breath test), a second manometry and 3-h postprandial esophageal pH monitoring were introduced to assess the results of eradication therapy, after a 3-month post-treatment period. All 29 selected H. pylori -positive patients became negative due to successful H. pylori eradication, evaluated by 13 C urea breath test after a 4-week post-treatment period. Post-eradication, 62.1% patients showed similar manometric pattern at baseline; 17.2% showed improvement; 17.2% normalization; and 3.4% deterioration of the manometric patterns. The DeMeester symptom scoring in the 3-h postprandial ambulatory esophageal pH monitoring was improved after eradication of H. pylori (median 47.47 vs. 22.00, Wilcoxon's singed rank; P=0.016). On comparing the pH monitoring studies for each patient at baseline and post-eradication period, 82.8% patients showed improvement and 17.2% deterioration of the DeMeester score. By using 3-h postprandial esophageal pH monitoring, this study showed, for the first time, that H. pylori eradication may positively influence GERD symptoms. Large-scale controlled relative studies are warranted to confirm these findings.

pH monitoring of gastro-oesophageal reflux before and after laparoscopic sleeve gastrectomy.

PubMed

Thereaux, J; Barsamian, C; Bretault, M; Dusaussoy, H; Lamarque, D; Bouillot, J-L; Czernichow, S; Carette, C

2016-03-01

Gastro-oesophageal reflux disease (GORD) is a common obesity-related co-morbidity that is assessed objectively by 24-h pH monitoring. Some concerns have been raised regarding the risk of de novo GORD or exacerbation of pre-existing GORD after laparoscopic sleeve gastrectomy. Here, 24-h pH monitoring was used to assess the influence of laparoscopic sleeve gastrectomy on postoperative GORD in obese patients with or without preoperative GORD. From July 2012 to September 2014, all patients scheduled for laparoscopic sleeve gastrectomy were invited to participate in a prospective follow-up. Patients who underwent preoperative 24-h pH monitoring were asked to repeat the examination 6 months after operation. GORD was defined as an oesophageal pH < 4 for at least 4·2 per cent of the total time recorded. Of 89 patients, 76 had preoperative pH monitoring for GORD evaluation and 50 had postoperative reassessment. Patients without (group 1, 29 patients) or with (group 2, 21 patients) preoperative GORD were similar regarding age, sex ratio and body mass index. In group 1, the median (i.q.r.) total time at pH < 4 was significantly higher after surgery than before: 5·6 (2·5-9·5) versus 1·6 (0·7-2·9) per cent (P < 0·001). Twenty of the 29 patients experienced de novo GORD as determined by 24-h pH monitoring (P < 0·001). In group 2, total time at pH < 4 after surgery was no different from the preoperative value: 5·9 (3·9-10·7) versus 7·7 (5·2-10·3) per cent (P = 0·296). Laparoscopic sleeve gastrectomy was associated with de novo GORD in over two-thirds of patients, but did not seem to exacerbate existing GORD. © 2016 BJS Society Ltd Published by John Wiley & Sons Ltd.

Water system virus detection

NASA Technical Reports Server (NTRS)

Fraser, A. S.; Wells, A. F.; Tenoso, H. J. (Inventor)

1978-01-01

The performance of a waste water reclamation system is monitored by introducing a non-pathogenic marker virus, bacteriophage F2, into the waste-water prior to treatment and, thereafter, testing the reclaimed water for the presence of the marker virus. A test sample is first concentrated by absorbing any marker virus onto a cellulose acetate filter in the presence of a trivalent cation at low pH and then flushing the filter with a limited quantity of a glycine buffer solution to desorb any marker virus present on the filter. Photo-optical detection of indirect passive immune agglutination by polystyrene beads indicates the performance of the water reclamation system in removing the marker virus. A closed system provides for concentrating any marker virus, initiating and monitoring the passive immune agglutination reaction, and then flushing the system to prepare for another sample.

Postoperative Gastroesophageal Reflux After Laparoscopic Heller-Dor for Achalasia: True Incidence with an Objective Evaluation.

PubMed

Salvador, Renato; Pesenti, Elisa; Gobbi, Laura; Capovilla, Giovanni; Spadotto, Lorenzo; Voltarel, Guerrino; Cavallin, Francesco; Nicoletti, Loredana; Valmasoni, Michele; Ruol, Alberto; Merigliano, Stefano; Costantini, Mario

2017-01-01

The most common complication after laparoscopic Heller-Dor (LHD) is gastroesophageal reflux disease (GERD). The present study aimed (a) to analyze the true incidence of postoperative reflux by objectively assessing a large group of LHD patients and (b) to see whether the presence of typical GERD symptoms correlates with the real incidence of postoperative reflux. After LHD, patients were assessed by means of a symptom score, endoscopy, esophageal manometry, and 24-h pH monitoring. Patients were assigned to three groups: those did not accept to perform 24-h pH monitoring (group NP); those with normal postoperative pH findings (group A); and those with pathological postoperative acid exposure (group B). Four hundred sixty-three of the 806 LHD patients agreed to undergo follow-up 24-h pH monitoring. Normal pH findings were seen in 423 patients (group A, 91.4 %), while 40 (8.6 %) had a pathological acid exposure (group B). The median symptom scores were similar: 3.0 (IQR 0-8) in group A and 6.0 (IQR 0-10) in group B (p = 0.29). At endoscopy, the percentage of esophagitis was also similar (11 % in group A, 19 % in group B; p = 0.28). This study demonstrated that, after LHD was performed by experienced surgeons, the true incidence of postoperative GERD is very low. The incidence of this possible complication should be assessed by pH monitoring because endoscopic findings and symptoms may be misleading.

Long-term wireless pH monitoring of the distal esophagus: prolonging the test beyond 48 hours is unnecessary and may be misleading.

PubMed

Capovilla, G; Salvador, R; Spadotto, L; Voltarel, G; Pesenti, E; Perazzolo, A; Nicoletti, L; Merigliano, S; Costantini, M

2017-10-01

Wireless pH monitoring of the esophagus has been widely used to detect GERD for more than a decade. It is generally well tolerated and accepted by patients, but it is still unclear whether prolonging a recording beyond the usual 48 hours can improve the test's diagnostic value. The aim of this study is to examine the diagnostic yield of 96-hour pH monitoring vis-à-vis 24- and 48-hour tests, and to ascertain whether any gain in diagnostic terms was of genuine clinical utility. Patients with suspected GERD underwent 4-day PPI-off wireless pH monitoring of the distal esophagus. The capsule was inserted under endoscopic control, 6 cm above the squamocolumnar junction. Average acid exposure time was calculated after 24, 48, and 96 hours of recording. Ninety-nine patients completed the 96 hour test, and formed the study sample. The wireless test method was used in 42 patients (42.4%) unable to tolerate the traditional pH-monitoring catheter, and in 57 (57.6%) with a previous negative pH study despite symptoms suggestive of GERD. On complete analysis, 47 patients (47.5%) had a pathological test result: 19 patients within the first 24 hours (19.2%, 24 hour group); another 16 after 48 hours (+16.2%, 48 hour group), and a further 12 (+12.1%, 96 hour group) only after 96 hours of monitoring. All 47 patients with an abnormal acid exposure were offered and accepted surgery (10 patients) or medical therapy (37 patients). Clinical follow-up was obtained in all patients with a positive Bravo test result after a median 67 months (IQR: 38-98) using a validated symptom questionnaire. A good outcome after fundoplication or medical therapy was achieved in 73.7% of patients in the 24 hour group, in 62.5% of those in the 48 hour group, and in only 25% of those in the 96 hour group, P = 0.02. Long-term wireless pH monitoring enables an increase in the diagnostic yield over traditional 24- and 48-hour pH studies, but prolonging the test may constitute an unwanted bias and prompt the recruitment of more complex patients, in whom the outcome of surgical or medical therapy may prove less than satisfactory. These findings should be taken into account when establishing the guidelines for assessing GERD with such long-term pH monitoring methods. © The Authors 2017. Published by Oxford University Press on behalf of International Society for Diseases of the Esophagus. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

[Comparative study on 24-hour multichannel intraluminal impedance-pH monitoring and Dx-pH monitoring in the diagnosis of laryngopharyngeal reflux].

PubMed

Wang, J S; Li, J R

2018-04-07

Objective: The consistency and characteristics of 24-hour multichannel intraluminal impedance(MII)-pH monitoring and Dx-pH monitoring in the diagnosis of laryngopharyngeal reflux were investigated. Methods: Fifty-two patients with laryngopharyngeal reflux related symptoms or disease between March and October 2017 were included in this study.All patients were evaluated with 24-hour MII-pH monitoring and Dx-pH monitoring at the same time, recording each patient's number of positive laryngopharyngeal reflux events, time of acid clearance and Ryan index.The data was analysed with Mann-Whitney U test and consistency check. Results: Among all 52 patients, 16 patients(30.7%) had a positive MII-pH monitoring result and 14 patients(26.9%) had a positive Dx-pH monitoring results.The consistency of both technique for measurement of laryngopharyngeal reflux was general(κ=0.626). With MII-pH monitoring for reference, the sensitivity and specificity of 24-hour pH monitoring were 68.8% and 91.7%.A total of 62 positive reflux events(pH<4) were measured with MII-pH monitoring, and 50 positive reflux events(upright pH<5.5 or supine pH<5.0)were detected by Dx-pH monitoring.There were 44 positive reflux events detected by both techniques, the mean time of acid clearance was 22.8[13.5; 42.6] s. Correspondingly, 18 reflux events were measured by MII-pH monitoring without positive results of Dx-pH monitoring, the mean time of acid clearance was 5.2[3.5; 6.5] s. There was significant difference in the time of acid clearance between two groups( U =858.5, P <0.05). Conclusions: Dx-pH monitoring can accurately measure the change of pH value in airway, but exists the possibility of misdiagnosis especially when the time of acid clearance in laryngopharynx is short. MII-pH and Dx-pH monitoring can be complementary technique in the diagnosis of laryngopharyngeal reflux.

Pharmacological MRI (phMRI) of the Human Central Nervous System.

PubMed

Lanfermann, H; Schindler, C; Jordan, J; Krug, N; Raab, P

2015-10-01

Pharmacological magnetic resonance imaging (phMRI) of the central nervous system (CNS) addresses the increasing demands in the biopharma industry for new methods that can accurately predict, as early as possible, whether novel CNS agents will be effective and safe. Imaging of physiological and molecular-level function can provide a more direct measure of a drug mechanism of action, enabling more predictive measures of drug activity. The availability of phMRI of the nervous system within the professional infrastructure of the Clinical Research Center (CRC) Hannover as proof of concept center ensures that advances in basic science progress swiftly into benefits for patients. Advanced standardized MRI techniques including quantitative MRI, kurtosis determination, functional MRI, and spectroscopic imaging of the entire brain are necessary for phMRI. As a result, MR scanners will evolve into high-precision measuring instruments for assessment of desirable and undesirable effects of drugs as the basic precondition for individually tailored therapy. The CRC's Imaging Unit with high-end large-scale equipment will allow the following unique opportunities: for example, identification of MR-based biomarkers to assess the effect of drugs (surrogate parameters), establishment of normal levels and reference ranges for MRI-based biomarkers, evaluation of the most relevant MRI sequences for drug monitoring in outpatient care. Another very important prerequisite for phMRI is the MHH Core Facility as the scientific and operational study unit of the CRC partner Hannover Medical School. This unit is responsible for the study coordination, conduction, complete study logistics, administration, and application of the quality assurance system based on required industry standards.

Effects of gastric pH on oral drug absorption: In vitro assessment using a dissolution/permeation system reflecting the gastric dissolution process.

PubMed

Kataoka, Makoto; Fukahori, Miho; Ikemura, Atsumi; Kubota, Ayaka; Higashino, Haruki; Sakuma, Shinji; Yamashita, Shinji

2016-04-01

The aim of the present study was to evaluate the effects of gastric pH on the oral absorption of poorly water-soluble drugs using an in vitro system. A dissolution/permeation system (D/P system) equipped with a Caco-2 cell monolayer was used as the in vitro system to evaluate oral drug absorption, while a small vessel filled with simulated gastric fluid (SGF) was used to reflect the gastric dissolution phase. After applying drugs in their solid forms to SGF, SGF solution containing a 1/100 clinical dose of each drug was mixed with the apical solution of the D/P system, which was changed to fasted state-simulated intestinal fluid. Dissolved and permeated amounts on applied amount of drugs were then monitored for 2h. Similar experiments were performed using the same drugs, but without the gastric phase. Oral absorption with or without the gastric phase was predicted in humans based on the amount of the drug that permeated in the D/P system, assuming that the system without the gastric phase reflected human absorption with an elevated gastric pH. The dissolved amounts of basic drugs with poor water solubility, namely albendazole, dipyridamole, and ketoconazole, in the apical solution and their permeation across a Caco-2 cell monolayer were significantly enhanced when the gastric dissolution process was reflected due to the physicochemical properties of basic drugs. These amounts resulted in the prediction of higher oral absorption with normal gastric pH than with high gastric pH. On the other hand, when diclofenac sodium, the salt form of an acidic drug, was applied to the D/P system with the gastric phase, its dissolved and permeated amounts were significantly lower than those without the gastric phase. However, the oral absorption of diclofenac was predicted to be complete (96-98%) irrespective of gastric pH because the permeated amounts of diclofenac under both conditions were sufficiently high to achieve complete absorption. These estimations of the effects of gastric pH on the oral absorption of poorly water-soluble drugs were consistent with observations in humans. In conclusion, the D/P system with the gastric phase may be a useful tool for better predicting the oral absorption of poorly water-soluble basic drugs. In addition, the effects of gastric pH on the oral absorption of poorly water-soluble drugs may be evaluated by the D/P system with and without the gastric phase. Copyright © 2016 Elsevier B.V. All rights reserved.

Ratiometric photoluminescence sensing based on Ti3C2 MXene quantum dots as an intracellular pH sensor.

PubMed

Chen, Xu; Sun, Xueke; Xu, Wen; Pan, Gencai; Zhou, Donglei; Zhu, Jinyang; Wang, He; Bai, Xue; Dong, Biao; Song, Hongwei

2018-01-18

Intracellular pH sensing is of importance and can be used as an indicator for monitoring the evolution of various diseases and the health of cells. Here, we developed a new class of surface-functionalized MXene quantum dots (QDs), Ti 3 C 2 , by the sonication cutting and hydrothermal approach and further explored their intracellular pH sensing. The functionalized Ti 3 C 2 QDs exhibit bright excitation-dependent blue photoluminescence (PL) originating from the size effect and surface defects. Meanwhile, Ti 3 C 2 QDs demonstrate a high PL response induced by the deprotonation of the surface defects. Furthermore, combining the highly pH sensitive Ti 3 C 2 QDs with the pH insensitive [Ru(dpp) 3 ]Cl 2 , we developed a ratiometric pH sensor to quantitatively monitor the intracellular pH values. These novel MXene quantum dots can serve as a promising platform for developing practical fluorescent nanosensors.

Long period grating-based fiber-optic PH sensor for ocean monitoring

NASA Astrophysics Data System (ADS)

Wang, Ke; Klimov, Denis; Kolber, Zbigniew

2007-09-01

A fiber-optic PH sensor is developed based-on the long period grating (LPG). The LPG is fabricated by using CO II laser with a point-by-point technique. Then the grating portion is coated with PH sensitive hydrogel. The hydrogel, made of PVA/PAA, swells its volume in response to the PH change in the surrounding environment and results in a change in the refractive index. As a result, the LPG can response to the refractive index change in the coating by shifting its wavelength. Therefore, change in refractive index can be measured by tracking the wavelength shift using an optical spectrum analyzer (OSA). In this research, the LPG is dip-coated by the hydrogel. A chemostat is designed to simulate the marine environment. The PH in the chemostat is varied by controlling the CO II concentration in the sea water. A PH resolution 0.046/nm using the OSA has been obtained. This sensor is designed to monitor the sea water PH change in a long term basis.

40 CFR 98.324 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Tracking System Handbook Number: PH-08-V-1, January 1, 2008 (incorporated by reference, see § 98.7). You... paragraphs (d)(1) through (d)(2) of this section. (1) ASTM D1945-03, Standard Test Method for Analysis of... Reformed Gas by Gas Chromatography; ASTM D4891-89 (Reapproved 2006), Standard Test Method for Heating Value...

Precise detection of pH inside large unilamellar vesicles using membrane-impermeable dendritic porphyrin-based nanoprobes.

PubMed

Leiding, Thom; Górecki, Kamil; Kjellman, Tomas; Vinogradov, Sergei A; Hägerhäll, Cecilia; Arsköld, Sindra Peterson

2009-05-15

Accurate real-time measurements of proton concentration gradients are pivotal to mechanistic studies of proton translocation by membrane-bound enzymes. Here we report a detailed characterization of the pH-sensitive fluorescent nanoprobe Glu(3), which is well suited for pH measurements in microcompartmentalized biological systems. The probe is a polyglutamic porphyrin dendrimer in which multiple carboxylate termini ensure its high water solubility and prevent its diffusion across phospholipid membranes. The probe's pK is in the physiological pH range, and its protonation can be followed ratiometrically by absorbance or fluorescence in the ultraviolet-visible spectral region. The usefulness of the probe was enhanced by using a semiautomatic titration system coupled to a charge-coupled device (CCD) spectrometer, enabling fast and accurate titrations and full spectral coverage of the system at millisecond time resolution. The probe's pK was measured in bulk solutions as well as inside large unilamellar vesicles in the presence of physiologically relevant ions. Glu(3) was found to be completely membrane impermeable, and its distinct spectroscopic features permit pH measurements inside closed membrane vesicles, enabling quantitative mechanistic studies of membrane-spanning proteins. Performance of the probe was demonstrated by monitoring the rate of proton leakage through the phospholipid bilayer in large vesicles with and without the uncoupler gramicidin present. Overall, as a probe for biological proton translocation measurements, Glu(3) was found to be superior to the commercially available pH indicators.

Graphite Screen-Printed Electrodes Applied for the Accurate and Reagentless Sensing of pH.

PubMed

Galdino, Flávia E; Smith, Jamie P; Kwamou, Sophie I; Kampouris, Dimitrios K; Iniesta, Jesus; Smith, Graham C; Bonacin, Juliano A; Banks, Craig E

2015-12-01

A reagentless pH sensor based upon disposable and economical graphite screen-printed electrodes (GSPEs) is demonstrated for the first time. The voltammetric pH sensor utilizes GSPEs which are chemically pretreated to form surface immobilized oxygenated species that, when their redox behavior is monitored, give a Nernstian response over a large pH range (1-13). An excellent experimental correlation is observed between the voltammetric potential and pH over the entire pH range of 1-13 providing a simple approach with which to monitor solution pH. Such a linear response over this dynamic pH range is not usually expected but rather deviation from linearity is encountered at alkaline pH values; absence of this has previously been attributed to a change in the pKa value of surface immobilized groups from that of solution phase species. This non-deviation, which is observed here in the case of our facile produced reagentless pH sensor and also reported in the literature for pH sensitive compounds immobilized upon carbon electrodes/surfaces, where a linear response is observed over the entire pH range, is explained alternatively for the first time. The performance of the GSPE pH sensor is also directly compared with a glass pH probe and applied to the measurement of pH in "real" unbuffered samples where an excellent correlation between the two protocols is observed validating the proposed GSPE pH sensor.

Use of the fluorescence of rhodamine B for the pH sensing of a glycine solution

NASA Astrophysics Data System (ADS)

Zhang, Weiwei; Shi, Kaixing; Shi, Jiulin; He, Xingdao

2016-10-01

The fluorescence of rhodamine B can be strongly affected by its environmental pH value. By directly introducing the dye into various glycine solution, the fluorescence was used to monitor the pH value in the range of 5.9 6.7. Two newly developed techniques for broadband analysis, the barycenter technique and the self-referenced intensity ratio technique, were employed to retrieve the pH sensing functions. While compared with traditional techniques, e.g. the peak shift monitoring, both the two new techniques presented finer precision. The obtained sensing functions may find their applications in the test of biochemical samples, body tissue fluid, water quality, etc.

Salivary pH as a marker of plasma adiponectin concentrations in Women.

PubMed

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 < 0.001). The proportion of the variance of plasma adiponectin levels explained by the salivary pH (R2) was 10.8% (p < 0.001). Plasma adiponectin levels progressively increased across 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.

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

PubMed

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.

3D Printing-Based Integrated Water Quality Sensing System

PubMed Central

Banna, Muinul; Bera, Kaustav; Sochol, Ryan; Lin, Liwei; Najjaran, Homayoun; Sadiq, Rehan; Hoorfar, Mina

2017-01-01

The online and accurate monitoring of drinking water supply networks is critically in demand to rapidly detect the accidental or deliberate contamination of drinking water. At present, miniaturized water quality monitoring sensors developed in the laboratories are usually tested under ambient pressure and steady-state flow conditions; however, in Water Distribution Systems (WDS), both the pressure and the flowrate fluctuate. In this paper, an interface is designed and fabricated using additive manufacturing or 3D printing technology—material extrusion (Trade Name: fused deposition modeling, FDM) and material jetting—to provide a conduit for miniaturized sensors for continuous online water quality monitoring. The interface is designed to meet two main criteria: low pressure at the inlet of the sensors and a low flowrate to minimize the water bled (i.e., leakage), despite varying pressure from WDS. To meet the above criteria, a two-dimensional computational fluid dynamics model was used to optimize the geometry of the channel. The 3D printed interface, with the embedded miniaturized pH and conductivity sensors, was then tested at different temperatures and flowrates. The results show that the response of the pH sensor is independent of the flowrate and temperature. As for the conductivity sensor, the flowrate and temperature affect only the readings at a very low conductivity (4 µS/cm) and high flowrates (30 mL/min), and a very high conductivity (460 µS/cm), respectively. PMID:28594387

Open Source Platform Application to Groundwater Characterization and Monitoring

NASA Astrophysics Data System (ADS)

Ntarlagiannis, D.; Day-Lewis, F. D.; Falzone, S.; Lane, J. W., Jr.; Slater, L. D.; Robinson, J.; Hammett, S.

2017-12-01

Groundwater characterization and monitoring commonly rely on the use of multiple point sensors and human labor. Due to the number of sensors, labor, and other resources needed, establishing and maintaining an adequate groundwater monitoring network can be both labor intensive and expensive. To improve and optimize the monitoring network design, open source software and hardware components could potentially provide the platform to control robust and efficient sensors thereby reducing costs and labor. This work presents early attempts to create a groundwater monitoring system incorporating open-source software and hardware that will control the remote operation of multiple sensors along with data management and file transfer functions. The system is built around a Raspberry PI 3, that controls multiple sensors in order to perform on-demand, continuous or `smart decision' measurements while providing flexibility to incorporate additional sensors to meet the demands of different projects. The current objective of our technology is to monitor exchange of ionic tracers between mobile and immobile porosity using a combination of fluid and bulk electrical-conductivity measurements. To meet this objective, our configuration uses four sensors (pH, specific conductance, pressure, temperature) that can monitor the fluid electrical properties of interest and guide the bulk electrical measurement. This system highlights the potential of using open source software and hardware components for earth sciences applications. The versatility of the system makes it ideal for use in a large number of applications, and the low cost allows for high resolution (spatially and temporally) monitoring.

Ferrocene functionalized graphene based electrode for the electro-Fenton oxidation of ciprofloxacin.

PubMed

Divyapriya, Govindaraj; Nambi, Indumathi; Senthilnathan, Jaganathan

2018-05-26

Ferrocene functionalized graphene based graphite felt electrode was firstly investigated for heterogeneous electro-Fenton oxidation of ciprofloxacin in neutral pH condition. Electrochemical reduction of Ferrocene functionalized graphene oxide (Fc-ErGO) was performed by cyclic voltammetry technique. At neutral pH condition, Fc-ErGO electrode (0.035 min ─1 ) exhibited ∼3 times and ∼9 times higher removal rates in comparison with plane ErGO (0.010 min ─1 ) and plane graphite felt (0.004 min ─1 ) electrodes respectively. The effect of pH and applied potential were studied for the degradation of ciprofloxacin in Fc-ErGO based electrode. Higher removal rate was observed at acidic pH (0.222 min ─1 ), whereas alkaline pH showed lower removal efficiency (0.014 min ─1 ). > 99% removal of ciprofloxacin was achieved with in 15 min and 120 min of reactions period at pH 3.0 and pH 7.0, respectively. H 2 O 2 generation was found to be high in plane ErGO electrode system in all of the pH conditions. Owing to the high redox ability of ferrocene, Fc-ErGO electrode generated high concentration of OH radicals (426 μM pH 3.0; 247 μM pH 7.0; 210 μM pH 9.0) than ErGO and plane graphite felt electrodes; The electrode reusability study was performed to understand the electrode stability. There was no significant change in removal efficiency even after the 5th cycle of reusability study at both acidic and neutral conditions. The possible mechanism of oxidation in Fc-ErGO based electro-Fenton process was also proposed based on the continuous monitoring of H 2 O 2 and OH radicals generated in the system. Copyright © 2018. Published by Elsevier Ltd.

Self-adaption of methane-producing communities to pH disturbance at different acetate concentrations by shifting pathways and population interaction.

PubMed

Hao, Liping; Lü, Fan; Li, Lei; Wu, Qing; Shao, Liming; He, Pinjing

2013-07-01

To investigate the competition among acetate-utilizing microorganisms at different acetate levels, bioconversion processes of 50, 100, 150 and 200 mM acetate in the presence and absence of methanogenic inhibitor CH3F were monitored in thermophilic methanogenic system. The successive response of methane-producing community during the deteriorative and recovery phases caused by pH disturbance was analyzed. High acetate concentration (>50mM) inhibited the activity of acetoclastic methanogenesis (AM). The increasing pH (>7.5) enhanced this inhibition. The syntrophic acetate oxidizing (SAO) bacteria and hydrogenotrophic methanogens including Methanomicrobiales and Methanobacteirales were more tolerant to the stress from high acetate concentration and high pH. Resumption from alkali condition to normal pH stimulated the growth of acetate oxidizing syntrophs. The reaction rate of SAO-HM was lower than that of AM. These results point to the possibility to regenerate the deteriorated anaerobic digesters by addition of acclimatized inocula rich in acetate-oxidizing syntrophs. Copyright © 2013 Elsevier Ltd. All rights reserved.

Synchronous Bioimaging of Intracellular pH and Chloride Based on LSS Fluorescent Protein.

PubMed

Paredes, Jose M; Idilli, Aurora I; Mariotti, Letizia; Losi, Gabriele; Arslanbaeva, Lyaysan R; Sato, Sebastian Sulis; Artoni, Pietro; Szczurkowska, Joanna; Cancedda, Laura; Ratto, Gian Michele; Carmignoto, Giorgio; Arosio, Daniele

2016-06-17

Ion homeostasis regulates critical physiological processes in the living cell. Intracellular chloride concentration not only contributes in setting the membrane potential of quiescent cells but it also plays a role in modulating the dynamic voltage changes during network activity. Dynamic chloride imaging demands new tools, allowing faster acquisition rates and correct accounting of concomitant pH changes. Joining a long-Stokes-shift red-fluorescent protein to a GFP variant with high sensitivity to pH and chloride, we obtained LSSmClopHensor, a genetically encoded fluorescent biosensor optimized for the simultaneous chloride and pH imaging and requiring only two excitation wavelengths (458 and 488 nm). LSSmClopHensor allowed us to monitor the dynamic changes of intracellular pH and chloride concentration during seizure like discharges in neocortical brain slices. Only cells with tightly controlled resting potential revealed a narrow distribution of chloride concentration peaking at about 5 and 8 mM, in neocortical neurons and SK-N-SH cells, respectively. We thus showed that LSSmClopHensor represents a new versatile tool for studying the dynamics of chloride and proton concentration in living systems.

PH-sensitive fluorescence detection by diffuse fluorescence tomography

NASA Astrophysics Data System (ADS)

Li, Jiao; Gao, Feng; Duan, Linjing; Wang, Xin; Zhang, Limin; Zhao, Huijuan

2012-03-01

The importance of cellular pH has been shown clearly in the study of cell activity, pathological feature, drug metabolism, etc. Monitoring pH changes of living cells and imaging the regions with abnormal pH values in vivo could provide the physiologic and pathologic information for the research of the cell biology, pharmacokinetics, diagnostics and therapeutics of certain diseases such as cancer. Thus, pH-sensitive fluorescence imaging of bulk tissues has been attracting great attention in the regime of near-infrared diffuse fluorescence tomography (DFT), an efficient small-animal imaging tool. In this paper, the feasibility of quantifying pH-sensitive fluorescence targets in turbid medium is investigated using both time-domain and steady-state DFT methods. By use of the specifically designed time-domain and continuous-wave systems and the previously proposed image reconstruction scheme, we validate the method through 2-dimensional imaging experiments on a small-animal-sized phantom with multiply targets of distinct pH values. The results show that the approach can localize the targets with reasonable accuracy and achieve quantitative reconstruction of the pH-sensitive fluorescent yield.

A lipid-accumulating alga maintains growth in outdoor, alkaliphilic raceway pond with mixed microbial communities

DOE PAGES

Bell, Tisza A.S.; Prithiviraj, Bharath; Wahlen, Brad D.; ...

2016-01-07

Algal biofuels and valuable co-products are being produced in both open and closed cultivation systems. Growing algae in open pond systems may be a more economical alternative, but this approach allows environmental microorganisms to colonize the pond and potentially infect or outcompete the algal “crop.” In this study, we monitored the microbial community of an outdoor, open raceway pond inoculated with a high lipid-producing alkaliphilic alga, Chlorella vulgaris BA050. The strain C. vulgaris BA050 was previously isolated from Soap Lake, Washington, a system characterized by a high pH (~9.8). An outdoor raceway pond (200 L) was inoculated with C. vulgarismore » and monitored for 10 days and then the culture was transferred to a 2,000 L raceway pond and cultivated for an additional 6 days. Community DNA samples were collected over the 16-day period in conjunction with water chemistry analyses and cell counts. Universal primers for the SSU rRNA gene sequences for Eukarya, Bacteria, and Archaea were used for barcoded pyrosequence determination. The environmental parameters that most closely correlated with C. vulgaris abundance were pH and phosphate. Community analyses indicated that the pond system remained dominated by the Chlorella population (93% of eukaryotic sequences), but was also colonized by other microorganisms. Bacterial sequence diversity increased over time while archaeal sequence diversity declined over the same time period. Using SparCC co-occurrence network analysis, a positive correlation was observed between C. vulgaris and Pseudomonas sp. throughout the experiment, which may suggest a symbiotic relationship between the two organisms. The putative relationship coupled with high pH may have contributed to the success of C. vulgaris. As a result, the characterization of the microbial community dynamics of an alkaliphilic open pond system provides significant insight into open pond systems that could be used to control photoautotrophic biomass productivity in an open, non-sterile environment.« less

A Lipid-Accumulating Alga Maintains Growth in Outdoor, Alkaliphilic Raceway Pond with Mixed Microbial Communities

PubMed Central

Bell, Tisza A. S.; Prithiviraj, Bharath; Wahlen, Brad D.; Fields, Matthew W.; Peyton, Brent M.

2016-01-01

Algal biofuels and valuable co-products are being produced in both open and closed cultivation systems. Growing algae in open pond systems may be a more economical alternative, but this approach allows environmental microorganisms to colonize the pond and potentially infect or outcompete the algal “crop.” In this study, we monitored the microbial community of an outdoor, open raceway pond inoculated with a high lipid-producing alkaliphilic alga, Chlorella vulgaris BA050. The strain C. vulgaris BA050 was previously isolated from Soap Lake, Washington, a system characterized by a high pH (∼9.8). An outdoor raceway pond (200 L) was inoculated with C. vulgaris and monitored for 10 days and then the culture was transferred to a 2,000 L raceway pond and cultivated for an additional 6 days. Community DNA samples were collected over the 16-day period in conjunction with water chemistry analyses and cell counts. Universal primers for the SSU rRNA gene sequences for Eukarya, Bacteria, and Archaea were used for barcoded pyrosequence determination. The environmental parameters that most closely correlated with C. vulgaris abundance were pH and phosphate. Community analyses indicated that the pond system remained dominated by the Chlorella population (93% of eukaryotic sequences), but was also colonized by other microorganisms. Bacterial sequence diversity increased over time while archaeal sequence diversity declined over the same time period. Using SparCC co-occurrence network analysis, a positive correlation was observed between C. vulgaris and Pseudomonas sp. throughout the experiment, which may suggest a symbiotic relationship between the two organisms. The putative relationship coupled with high pH may have contributed to the success of C. vulgaris. The characterization of the microbial community dynamics of an alkaliphilic open pond system provides significant insight into open pond systems that could be used to control photoautotrophic biomass productivity in an open, non-sterile environment. PMID:26779138

A Lipid-Accumulating Alga Maintains Growth in Outdoor, Alkaliphilic Raceway Pond with Mixed Microbial Communities.

PubMed

Bell, Tisza A S; Prithiviraj, Bharath; Wahlen, Brad D; Fields, Matthew W; Peyton, Brent M

2015-01-01

Algal biofuels and valuable co-products are being produced in both open and closed cultivation systems. Growing algae in open pond systems may be a more economical alternative, but this approach allows environmental microorganisms to colonize the pond and potentially infect or outcompete the algal "crop." In this study, we monitored the microbial community of an outdoor, open raceway pond inoculated with a high lipid-producing alkaliphilic alga, Chlorella vulgaris BA050. The strain C. vulgaris BA050 was previously isolated from Soap Lake, Washington, a system characterized by a high pH (∼9.8). An outdoor raceway pond (200 L) was inoculated with C. vulgaris and monitored for 10 days and then the culture was transferred to a 2,000 L raceway pond and cultivated for an additional 6 days. Community DNA samples were collected over the 16-day period in conjunction with water chemistry analyses and cell counts. Universal primers for the SSU rRNA gene sequences for Eukarya, Bacteria, and Archaea were used for barcoded pyrosequence determination. The environmental parameters that most closely correlated with C. vulgaris abundance were pH and phosphate. Community analyses indicated that the pond system remained dominated by the Chlorella population (93% of eukaryotic sequences), but was also colonized by other microorganisms. Bacterial sequence diversity increased over time while archaeal sequence diversity declined over the same time period. Using SparCC co-occurrence network analysis, a positive correlation was observed between C. vulgaris and Pseudomonas sp. throughout the experiment, which may suggest a symbiotic relationship between the two organisms. The putative relationship coupled with high pH may have contributed to the success of C. vulgaris. The characterization of the microbial community dynamics of an alkaliphilic open pond system provides significant insight into open pond systems that could be used to control photoautotrophic biomass productivity in an open, non-sterile environment.

Pharmacological imaging as a tool to visualise dopaminergic neurotoxicity.

PubMed

Schrantee, A; Reneman, L

2014-09-01

Dopamine abnormalities underlie a wide variety of psychopathologies, including ADHD and schizophrenia. A new imaging technique, pharmacological magnetic resonance imaging (phMRI), is a promising non-invasive technique to visualize the dopaminergic system in the brain. In this review we explore the clinical potential of phMRI in detecting dopamine dysfunction or neurotoxicity, assess its strengths and weaknesses and identify directions for future research. Preclinically, phMRI is able to detect severe dopaminergic abnormalities quite similar to conventional techniques such as PET and SPECT. phMRI benefits from its high spatial resolution and the possibility to visualize both local and downstream effects of dopaminergic neurotransmission. In addition, it allows for repeated measurements and assessments in vulnerable populations. The major challenge is the complex interpretation of phMRI results. Future studies in patients with dopaminergic abnormalities need to confirm the currently reviewed preclinical findings to validate the technique in a clinical setting. Eventually, based on the current review we expect that phMRI can be of use in a clinical setting involving vulnerable populations (such as children and adolescents) for diagnosis and monitoring treatment efficacy. This article is part of the Special Issue Section entitled 'Neuroimaging in Neuropharmacology'. Copyright © 2013 Elsevier Ltd. All rights reserved.

Using eddy currents for noninvasive in vivo pH monitoring for bone tissue engineering.

PubMed

Beck-Broichsitter, Benedicta E; Daschner, Frank; Christofzik, David W; Knöchel, Reinhard; Wiltfang, Jörg; Becker, Stephan T

2015-03-01

The metabolic processes that regulate bone healing and bone induction in tissue engineering models are not fully understood. Eddy current excitation is widely used in technical approaches and in the food industry. The aim of this study was to establish eddy current excitation for monitoring metabolic processes during heterotopic osteoinduction in vivo. Hydroxyapatite scaffolds were implanted into the musculus latissimus dorsi of six rats. Bone morphogenetic protein 2 (BMP-2) was applied 1 and 2 weeks after implantation. Weekly eddy current excitation measurements were performed. Additionally, invasive pH measurements were obtained from the scaffolds using fiber optic detection devices. Correlations between the eddy current measurements and the metabolic values were calculated. The eddy current measurements and pH values decreased significantly in the first 2 weeks of the study, followed by a steady increase and stabilization at higher levels towards the end of the study. The measurement curves and statistical evaluations indicated a significant correlation between the resonance frequency values of the eddy current excitation measurements and the observed pH levels (p = 0.0041). This innovative technique was capable of noninvasively monitoring metabolic processes in living tissues according to pH values, showing a direct correlation between eddy current excitation and pH in an in vivo tissue engineering model.

Noninvasive fetal electrocardiography following intermittent umbilical cord occlusion in the preterm ovine fetus.

PubMed

Cleal, J K; Thomas, M; Hanson, M A; Paterson-Brown, S; Gardiner, H M; Green, L R

2010-03-01

To investigate whether a noninvasive fetal electrocardiography (fECG) system can identify cardiovascular responses to fetal hypoxaemia and validate the results using standard invasive fECG monitoring techniques. Prospective cohort study. Biological research facilities at The University of Southampton. Late gestation ovine fetuses; n = 5. Five fetal lambs underwent implantation of vascular catheters, umbilical cord occluder and invasive ECG chest electrodes under general anaesthesia (3% halothane/O(2)) at 119 days of gestation (term approximately 147 days of gestation). After 5 days of recovery blood pressure, blood gases, glucose and pH were monitored. At 124 and 125 days of gestation following a 10-minute baseline period a 90-second cord occlusion was applied. Noninvasive fetal ECG was recorded from maternal transabdominal electrodes using advanced signal-processing techniques, concurrently with invasive fECG recordings. Comparison of T:QRS ratios of the ECG waveform from noninvasive and invasive fECG monitoring systems. Our fECG monitoring system is able to demonstrate changes in waveforms during periods of hypoxaemia similar to those obtained invasively, which could indicate fetal distress. These findings may indicate a future use for noninvasive electrocardiography during human fetal monitoring both before and during labour in term and preterm pregnancies.

Nitrogen-rich functional groups carbon nanoparticles based fluorescent pH sensor with broad-range responding for environmental and live cells applications.

PubMed

Shi, Bingfang; Su, Yubin; Zhang, Liangliang; Liu, Rongjun; Huang, Mengjiao; Zhao, Shulin

2016-08-15

A nitrogen-rich functional groups carbon nanoparticles (N-CNs) based fluorescent pH sensor with a broad-range responding was prepared by one-pot hydrothermal treatment of melamine and triethanolamine. The as-prepared N-CNs exhibited excellent photoluminesence properties with an absolute quantum yield (QY) of 11.0%. Furthermore, the N-CNs possessed a broad-range pH response. The linear pH response range was 3.0 to 12.0, which is much wider than that of previously reported fluorescent pH sensors. The possible mechanism for the pH-sensitive response of the N-CNs was ascribed to photoinduced electron transfer (PET). Cell toxicity experiment showed that the as-prepared N-CNs exhibited low cytotoxicity and excellent biocompatibility with the cell viabilities of more than 87%. The proposed N-CNs-based pH sensor was used for pH monitoring of environmental water samples, and pH fluorescence imaging of live T24 cells. The N-CNs is promising as a convenient and general fluorescent pH sensor for environmental monitoring and bioimaging applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Matching phosphate and maleate buffer systems for dissolution of weak acids: Equivalence in terms of buffer capacity of bulk solution or surface pH?

PubMed

Cristofoletti, Rodrigo; Dressman, Jennifer B

2016-06-01

The development of in vitro dissolution tests able to anticipate the in vivo fate of drug products has challenged pharmaceutical scientists over time, especially in the case of ionizable compounds. In the seminal model proposed by Mooney et al. thirty-five years ago, the pH at the solid-liquid interface (pH0) was identified as a key parameter in predicting dissolution rate. In the current work it is demonstrated that the in vitro dissolution of the weak acid ibuprofen in maleate and phosphate buffer systems is a function of the pH0, which in turn is affected by properties of the drug and the medium. The reported pH0 for ibuprofen dissolution in bicarbonate buffer, the predominant buffer species in the human small intestine under fasting conditions, can be achieved by reducing the phosphate buffer concentration to 5.0mM or the maleate buffer concentration to 2.2mM. Using this approach to identify the appropriate buffer/buffer capacity combination for in vitro experiments in FaSSIF-type media, it would be possible to increase the physiological relevance of this important biopharmaceutics tool. However, the necessity of monitoring and adjusting the bulk pH during the experiments carried out in 5.0mM phosphate or 2.2mM maleate buffers must also be taken into consideration. Copyright © 2016 Elsevier B.V. All rights reserved.

Smartphone-Based pH Sensor for Home Monitoring of Pulmonary Exacerbations in Cystic Fibrosis

PubMed Central

Sun, Alexander; Phelps, Tom; Yao, Chengyang; Venkatesh, A. G.; Conrad, Douglas; Hall, Drew A.

2017-01-01

Currently, Cystic Fibrosis (CF) patients lack the ability to track their lung health at home, relying instead on doctor checkups leading to delayed treatment and lung damage. By leveraging the ubiquity of the smartphone to lower costs and increase portability, a smartphone-based peripheral pH measurement device was designed to attach directly to the headphone port to harvest power and communicate with a smartphone application. This platform was tested using prepared pH buffers and sputum samples from CF patients. The system matches within ~0.03 pH of a benchtop pH meter while fully powering itself and communicating with a Samsung Galaxy S3 smartphone paired with either a glass or Iridium Oxide (IrOx) electrode. The IrOx electrodes were found to have 25% higher sensitivity than the glass probes at the expense of larger drift and matrix sensitivity that can be addressed with proper calibration. The smartphone-based platform has been demonstrated as a portable replacement for laboratory pH meters, and supports both highly robust glass probes and the sensitive and miniature IrOx electrodes with calibration. This tool can enable more frequent pH sputum tracking for CF patients to help detect the onset of pulmonary exacerbation to provide timely and appropriate treatment before serious damage occurs. PMID:28556804

Smartphone-Based pH Sensor for Home Monitoring of Pulmonary Exacerbations in Cystic Fibrosis.

PubMed

Sun, Alexander; Phelps, Tom; Yao, Chengyang; Venkatesh, A G; Conrad, Douglas; Hall, Drew A

2017-05-30

Currently, Cystic Fibrosis (CF) patients lack the ability to track their lung health at home, relying instead on doctor checkups leading to delayed treatment and lung damage. By leveraging the ubiquity of the smartphone to lower costs and increase portability, a smartphone-based peripheral pH measurement device was designed to attach directly to the headphone port to harvest power and communicate with a smartphone application. This platform was tested using prepared pH buffers and sputum samples from CF patients. The system matches within ~0.03 pH of a benchtop pH meter while fully powering itself and communicating with a Samsung Galaxy S3 smartphone paired with either a glass or Iridium Oxide (IrOx) electrode. The IrOx electrodes were found to have 25% higher sensitivity than the glass probes at the expense of larger drift and matrix sensitivity that can be addressed with proper calibration. The smartphone-based platform has been demonstrated as a portable replacement for laboratory pH meters, and supports both highly robust glass probes and the sensitive and miniature IrOx electrodes with calibration. This tool can enable more frequent pH sputum tracking for CF patients to help detect the onset of pulmonary exacerbation to provide timely and appropriate treatment before serious damage occurs.

Environmental exposure modeling and monitoring of human pharmaceutical concentrations in the environment

USGS Publications Warehouse

Versteeg, D.J.; Alder, A. C.; Cunningham, V. L.; Kolpin, D.W.; Murray-Smith, R.; Ternes, T.

2005-01-01

Human pharmaceuticals are receiving increased attention as environmental contaminants. This is due to their biological activity and the number of monitoring programs focusing on analysis of these compounds in various environmental media and compartments. Risk assessments are needed to understand the implications of reported concentrations; a fundamental part of the risk assessment is an assessment of environmental exposures. The purpose of this chapter is to provide guidance on the use of predictive tools (e.g., models) and monitoring data in exposure assessments for pharmaceuticals in the environment. Methods to predict environmental concentrations from equations based on first principles are presented. These equations form the basis of existing GIS (geographic information systems)-based systems for understanding the spatial distribution of pharmaceuticals in the environment. The pharmaceutical assessment and transport (PhATE), georeferenced regional exposure assessment tool for European rivers (GREAT-ER), and geographical information system (GIS)-ROUT models are reviewed and recommendations are provided concerning the design and execution of monitoring studies. Model predictions and monitoring data are compared to evaluate the relative utility of each approach in environmental exposure assessments. In summary, both models and monitoring data can be used to define representative exposure concentrations of pharmaceuticals in the environment in support of environmental risk assessments.

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

PubMed

Su, Pai-Hsiang; Lai, Yen-Hsun

2017-01-01

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 (ΔpH env ), whether the concentration of ionophores used can effectively abolish the ΔpH env 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 ΔpH env 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 ΔpH env can be detected ranging from 0.15 to 0.33 pH units upon illumination. The concentration of the ionophore nigericin required to collapse the ΔpH env was then studied. The establishment of a non-destructive method of monitoring the stromal pH will be valuable for studying the roles of the ΔpH env in chloroplast physiology.

Monitoring of rapid blood pH variations by CO detection in breath with tunable diode laser

NASA Astrophysics Data System (ADS)

Kouznetsov, Andrian I.; Stepanov, Eugene V.; Zyrianov, Pavel V.; Shulagin, Yurii A.; Diachenko, Alexander I.; Gurfinkel, Youri I.

1997-06-01

Detection of endogenous carbon monoxide content in breath with tunable diode lasers (TDL) was proposed for noninvasive monitoring of rapid blood pH variation. Applied approach is based on high sensitivity of the haemoglobin and myoglobin affinity for CO to blood pH value and an ability to detect rapidly small variations of CO content in expired air. Breath CO absorption in 4.7 micrometers spectral region was carefully measured using PbSSe tunable diode laser that can provide 1 ppb CO concentration sensitivity and 10 s time constant. Applied TDL gas analyzer was used to monitor expired air of studied persons in physiological tests including hyperventilation and physical load. Simultaneous blood tests were conducted to demonstrate correlation between blood and breath chemical parameters.

Direct Estimation of Local pH Change at Infection Sites of Fungi in Potato Tubers.

PubMed

Tardi-Ovadia, R; Linker, R; Tsror Lahkim, L

2017-01-01

Fungi can modify the pH in or around the infected site via alkalization or acidification, and pH monitoring may provide valuable information on host-fungus interactions. The objective of the present study was to examine the ability of two fungi, Colletotrichum coccodes and Helminthosporium solani, to modify the pH of potato tubers during artificial inoculation in situ. Both fungi cause blemishes on potato tubers, which downgrades tuber quality and yield. Direct visualization and estimation of pH changes near the inoculation area were achieved using pH indicators and image analysis. The results showed that the pH of the area infected by either fungus increased from potato native pH of approximately 6.0 to 7.4 to 8.0. By performing simple analysis of the images, it was also possible to derive the growth curve of each fungus and estimate the lag phase of the radial growth: 10 days for C. coccodes and 17 days H. solani. In addition, a distinctive halo (an edge area with increased pH) was observed only during the lag phase of H. solani infection. pH modulation is a major factor in pathogen-host interaction and the proposed method offers a simple and rapid way to monitor these changes.

Proton mediated control of biochemical reactions with bioelectronic pH modulation

NASA Astrophysics Data System (ADS)

Deng, Yingxin; Miyake, Takeo; Keene, Scott; Josberger, Erik E.; Rolandi, Marco

2016-04-01

In Nature, protons (H+) can mediate metabolic process through enzymatic reactions. Examples include glucose oxidation with glucose dehydrogenase to regulate blood glucose level, alcohol dissolution into carboxylic acid through alcohol dehydrogenase, and voltage-regulated H+ channels activating bioluminescence in firefly and jellyfish. Artificial devices that control H+ currents and H+ concentration (pH) are able to actively influence biochemical processes. Here, we demonstrate a biotransducer that monitors and actively regulates pH-responsive enzymatic reactions by monitoring and controlling the flow of H+ between PdHx contacts and solution. The present transducer records bistable pH modulation from an “enzymatic flip-flop” circuit that comprises glucose dehydrogenase and alcohol dehydrogenase. The transducer also controls bioluminescence from firefly luciferase by affecting solution pH.

Molecular Wiring in Smart Dressings: Opening a New Route to Monitoring Wound pH

PubMed Central

McLister, Anna; Davis, James

2015-01-01

It has been proposed that fluctuations in wound pH can give valuable insights into the healing processes in chronic wounds, but acquiring such data can be a technological challenge especially where there is little sample available. Developments in voltammetric pH sensing have opened up new avenues for the design of probes that can function in ultra-small volumes and can be inherently disposable but, as yet few can meet the demands of wound monitoring. A preliminary investigation of the pH response of a new redox wire prepared from a peptide homopolymer of tryptophan is presented and its potential applicability as a sensing material for use in smart dressings is critically discussed. PMID:27417774

Water system virus detection

NASA Technical Reports Server (NTRS)

Fraser, A. S.; Wells, A. F.; Tenoso, H. J.

1975-01-01

A monitoring system developed to test the capability of a water recovery system to reject the passage of viruses into the recovered water is described. A nonpathogenic marker virus, bacteriophage F2, is fed into the process stream before the recovery unit and the reclaimed water is assayed for its presence. Detection of the marker virus consists of two major components, concentration and isolation of the marker virus, and detection of the marker virus. The concentration system involves adsorption of virus to cellulose acetate filters in the presence of trivalent cations and low pH with subsequent desorption of the virus using volumes of high pH buffer. The detection of the virus is performed by a passive immune agglutination test utilizing specially prepared polystyrene particles. An engineering preliminary design was performed as a parallel effort to the laboratory development of the marker virus test system. Engineering schematics and drawings of a fully functional laboratory prototype capable of zero-G operation are presented. The instrument consists of reagent pump/metering system, reagent storage containers, a filter concentrator, an incubation/detector system, and an electronic readout and control system.

Zr/ZrO2 sensors for in situ measurement of pH in high-temperature and -pressure aqueous solutions.

PubMed

Zhang, R H; Zhang, X T; Hu, S M

2008-04-15

The aim of this study is to develop new pH sensors that can be used to test and monitor hydrogen ion activity in hydrothermal conditions. A Zr/ZrO2 oxidation electrode is fabricated for in situ pH measurement of high-temperature aqueous solutions. This sensor responds rapidly and precisely to pH over a wide range of temperature and pressure. The Zr/ZrO2 electrode was made by oxidizing zirconium metal wire with Na2CO3 melt, which produced a thin film of ZrO2 on its surface. Thus, an oxidation-reduction electrode was produced. The Zr/ZrO2 electrode has a good electrochemical stability over a wide range of pH in high-temperature aqueous solutions when used with a Ag/AgCl reference electrode. Measurements of the Zr/ZrO2 sensor potential against a Ag/AgCl reference electrode is shown to vary linearly with pH between temperatures 20 and 200 degrees C. The slope of the potential versus pH at high temperature is slightly below the theoretical value indicated by the Nernst equation; such deviation is attributed to the fact that the sensor is not strictly at equilibrium with the solution to be tested in a short period of time. The Zr/ZrO2 sensor can be calibrated over the conditions that exist in the natural deep-seawater. Our studies showed that the Zr/ZrO2 electrode is a suitable pH sensor for the hydrothermal systems at midocean ridge or other geothermal systems with the high-temperature environment. Yttria-stabilized zirconia sensors have also been used to investigate the pH of hydrothermal fluids in hot springs vents at midocean ridge. These sensors, however, are not sensitive below 200 degrees C. Zr/ZrO2 sensors have wider temperature range and can be severed as good alternative sensors for measuring the pH of hydrothermal fluids.

Application of excitation and emission matrix fluorescence (EEM) and UV-vis absorption to monitor the characteristics of Alizarin Red S (ARS) during electro-Fenton degradation process.

PubMed

Lai, Bo; Zhou, Yuexi; Wang, Juling; Yang, Zhishan; Chen, Zhiqiang

2013-11-01

Oxidative degradation of Alizarin Red S (ARS) in aqueous solutions by using electro-Fenton was studied. At first, effect of operating parameters such as current density, aeration rate and initial pH on the degradation of ARS were studied by using UV-vis spectrum, respectively. Then, under the optimal operating conditions (current density: 10.0mAcm(-2), aeration rate: 1000mLmin(-1), initial pH: 2.8), the identification of degradation products of ARS was carried out by using GC-MS and HPLC, meanwhile its degradation pathway was proposed according to the intermediates. Considering the location, intensity and intensity ratio of fluorescence center peak of the ARS in aqueous solution, a convenient and quick monitoring method by using excitation-emission matrix fluorescence spectrum technology was developed to monitor the degradation degree of ARS through electro-Fenton process. Furthermore, it is suggested that the developed method would be promising for the quick analysis and evaluation of the degradation degree of the pollutants with π-conjugated system. Copyright © 2013 Elsevier Ltd. All rights reserved.

New insights into biogeochemical processing gained from sub-daily river monitoring

NASA Astrophysics Data System (ADS)

Halliday, S. J.; Wade, A. J.; Skeffington, R. A.; Bowes, M.; Palmer-Felgate, E.; Loewenthal, M.; Jarvie, H.; Neal, C.; Reynolds, B.; Gozzard, E.; Newman, J.

2012-12-01

This talk will focus on the insights obtained from sub-daily hydrochemical monitoring for a sustained time periods (> 1 year), at multiple sites within a catchment and across different catchment types. Sub-daily instream hydrochemical dynamics were investigated, using non-stationary time-series analysis techniques, for two catchments representative of upland and lowland UK. The River Hafren at Plynlimon, mid-Wales drains an upland catchment where half the land cover is unmanaged moorland and the other half is first generation plantation forestry. The Hafren was monitored at two sites on a 7-hourly basis, between March 2007 and January 2009, using a Xian automatic sampler. The River Enborne, Berkshire, southeast England, is a rural lowland catchment, impacted by agricultural runoff, and septic tank and sewage treatment works discharges. The Enborne was monitored on an hourly basis between November 2009 and February 2012, using in situ field deployable analytical equipment to measure: Total Reactive Phosphorus (TRP: Systea Micromac C), Nitrate (Hach-Lange Nitratax), pH, dissolved oxygen, conductivity and water temperature (YSI 6600 Multi-parameter sonde). The results reveal complex diurnal patterns which exhibit seasonal changes in phase and amplitude, and are influenced by both flow conditions and nutrient sources. The comparison of the upland and lowland nitrate time series highlights how the different nitrogen sources within each system results in marked differences in the seasonal and diurnal dynamics, with a seasonal maximum in winter and a single peak diurnal cycle in the upland system, compared to a summer maximum and a two peak diurnal cycle in the lowland system. The analysis of TRP and nitrate concentrations in the Enborne catchment, in combination with flow, pH, dissolved oxygen, conductivity and water temperature, allowed the main processes controlling the observed sub-daily nutrient dynamics to be investigated. The different monitoring approaches adopted revealed the complexities involved in the accurate extraction of diurnal dynamics under lower frequency sampling, and the inherent issues of aliasing. Monitoring for 2 years also allowed an initial assessment of the inter-annual variability in the observed dynamics.

Guidelines and standard procedures for continuous water-quality monitors: Site selection, field operation, calibration, record computation, and reporting

USGS Publications Warehouse

Wagner, Richard J.; Mattraw, Harold C.; Ritz, George F.; Smith, Brett A.

2000-01-01

The U.S. Geological Survey uses continuous water-quality monitors to assess variations in the quality of the Nation's surface water. A common system configuration for data collection is the four-parameter water-quality monitoring system, which collects temperature, specific conductance, dissolved oxygen, and pH data, although systems can be configured to measure other properties such as turbidity or chlorophyll. The sensors that are used to measure these water properties require careful field observation, cleaning, and calibration procedures, as well as thorough procedures for the computation and publication of final records. Data from sensors can be used in conjunction with collected samples and chemical analyses to estimate chemical loads. This report provides guidelines for site-selection considerations, sensor test methods, field procedures, error correction, data computation, and review and publication processes. These procedures have evolved over the past three decades, and the process continues to evolve with newer technologies.

Reaction between peroxynitrite and triphenylphosphonium-substituted arylboronic acid isomers–Identification of diagnostic marker products and biological implications

PubMed Central

Sikora, Adam; Zielonka, Jacek; Adamus, Jan; Debski, Dawid; Dybala-Defratyka, Agnieszka; Michalowski, Bartosz; Joseph, Joy; Hartley, Richard C.; Murphy, Michael P.; Kalyanaraman, Balaraman

2013-01-01

Aromatic boronic acids react rapidly with peroxynitrite (ONOO−) to yield phenols as major products. This reaction was used to monitor ONOO− formation in cellular systems. Previously, we proposed that the reaction between ONOO− and arylboronates (PhB(OH)2) yields a phenolic product (major pathway) and a radical pair PhB(OH)2O•−…•NO2 (minor pathway). [Sikora A. et al., Chem Res Toxicol 24, 687-97, 2011]. In this study, we investigated the influence of a bulky triphenylphosphonium (TPP) group on the reaction between ONOO− and mitochondria-targeted arylboronate isomers (o-, m-, and p-MitoPhB(OH)2). Results from the electron paramagnetic resonance (EPR) spin-trapping experiments unequivocally showed the presence of a phenyl radical intermediate from meta and para isomers, and not from the ortho isomer. The yield of o-MitoPhNO2 formed from the reaction between o-MitoPhB(OH)2 and ONOO− was not diminished by phenyl radical scavengers, suggesting a rapid fragmentation of the o-MitoPhB(OH)2O•− radical anion with subsequent reaction of the resulting phenyl radical with •NO2 in the solvent cage. The DFT quantum mechanical calculations showed that the energy barrier for the dissociation of o-MitoPhB(OH)2O•− radical anion is significantly lower than that of m-MitoPhB(OH)2O•− and p-MitoPhB(OH)2O•− radical anions. The nitrated product, o-MitoPhNO2, is not formed by nitrogen dioxide radical generated by myeloperoxidase in the presence of nitrite anion and hydrogen peroxide, indicating that this specific nitrated product may be used as a diagnostic marker product for ONOO−. Incubation of o-MitoPhB(OH)2 with RAW 264.7 macrophages activated to produce ONOO− yielded the corresponding phenol o-MitoPhOH as well as the diagnostic nitrated product, o-MitoPhNO2. We conclude that the ortho isomer probe reported here is most suitable for specific detection of ONOO− in biological systems. PMID:23611338

Evaluating Carbonate System Algorithms in a Nearshore System: Does Total Alkalinity Matter?

PubMed Central

Sweet, Julia; Brzezinski, Mark A.; McNair, Heather M.; Passow, Uta

2016-01-01

Ocean acidification is a threat to many marine organisms, especially those that use calcium carbonate to form their shells and skeletons. The ability to accurately measure the carbonate system is the first step in characterizing the drivers behind this threat. Due to logistical realities, regular carbonate system sampling is not possible in many nearshore ocean habitats, particularly in remote, difficult-to-access locations. The ability to autonomously measure the carbonate system in situ relieves many of the logistical challenges; however, it is not always possible to measure the two required carbonate parameters autonomously. Observed relationships between sea surface salinity and total alkalinity can frequently provide a second carbonate parameter thus allowing for the calculation of the entire carbonate system. Here, we assessed the rigor of estimating total alkalinity from salinity at a depth <15 m by routinely sampling water from a pier in southern California for several carbonate system parameters. Carbonate system parameters based on measured values were compared with those based on estimated TA values. Total alkalinity was not predictable from salinity or from a combination of salinity and temperature at this site. However, dissolved inorganic carbon and the calcium carbonate saturation state of these nearshore surface waters could both be estimated within on average 5% of measured values using measured pH and salinity-derived or regionally averaged total alkalinity. Thus we find that the autonomous measurement of pH and salinity can be used to monitor trends in coastal changes in DIC and saturation state and be a useful method for high-frequency, long-term monitoring of ocean acidification. PMID:27893739

Evaluating Carbonate System Algorithms in a Nearshore System: Does Total Alkalinity Matter?

PubMed

Jones, Jonathan M; Sweet, Julia; Brzezinski, Mark A; McNair, Heather M; Passow, Uta

2016-01-01

Ocean acidification is a threat to many marine organisms, especially those that use calcium carbonate to form their shells and skeletons. The ability to accurately measure the carbonate system is the first step in characterizing the drivers behind this threat. Due to logistical realities, regular carbonate system sampling is not possible in many nearshore ocean habitats, particularly in remote, difficult-to-access locations. The ability to autonomously measure the carbonate system in situ relieves many of the logistical challenges; however, it is not always possible to measure the two required carbonate parameters autonomously. Observed relationships between sea surface salinity and total alkalinity can frequently provide a second carbonate parameter thus allowing for the calculation of the entire carbonate system. Here, we assessed the rigor of estimating total alkalinity from salinity at a depth <15 m by routinely sampling water from a pier in southern California for several carbonate system parameters. Carbonate system parameters based on measured values were compared with those based on estimated TA values. Total alkalinity was not predictable from salinity or from a combination of salinity and temperature at this site. However, dissolved inorganic carbon and the calcium carbonate saturation state of these nearshore surface waters could both be estimated within on average 5% of measured values using measured pH and salinity-derived or regionally averaged total alkalinity. Thus we find that the autonomous measurement of pH and salinity can be used to monitor trends in coastal changes in DIC and saturation state and be a useful method for high-frequency, long-term monitoring of ocean acidification.

Quantifying Laryngopharyngeal Reflux in Singers: Perceptual and Objective Findings

PubMed Central

Lewis, Vicki M.

2017-01-01

This study examines the relationship between laryngopharyngeal reflux (LPR) symptoms and oropharyngeal pH levels in singers. We hypothesized that reported symptoms would correlate with objective measures of pH levels from the oropharynx, including the number and total duration of reflux episodes. Twenty professional/semiprofessional singers completed the Reflux Symptom Index (RSI) and underwent oropharyngeal pH monitoring. Mild, moderate, or severe pH exposure was recorded during oropharyngeal pH monitoring. Correlations were performed to examine potential relationships between reflux symptoms and duration of LPR episodes. Symptom severity did not correlate with pH levels; however, we found a number of covariances of interest. Large sample sizes are necessary to determine if true correlations exist. Our results suggest that singers may exhibit enhanced sensitivity to LPR and may therefore manifest symptoms, even in response to subtle changes in pH. This study emphasizes the importance of sensitive and objective measures of reflux severity as well as consideration of the cumulative time of reflux exposure in addition to the number of reflux episodes. PMID:29098155

Microbial plant litter decomposition in aquatic and terrestrial boreal systems along a natural fertility gradient

NASA Astrophysics Data System (ADS)

Soares, A. Margarida P. M.; Kritzberg, Emma S.; Rousk, Johannes

2017-04-01

Plant litter decomposition is a global ecosystem process, with a crucial role in carbon and nutrient cycling. The majority of litter processing occurs in terrestrial systems, but an important fraction also takes place in inland waters. Among environmental factors, pH impacts the litter decomposition through its selective influence on microbial decomposers. Fungal communities are less affected by pH than bacteria, possibly owing to a wider pH tolerance by this group. On the other hand, bacterial pH optima are constrained to a narrower range of pH values. The microbial decomposition of litter is universally nutrient limited; but few comparisons exist between terrestrial and aquatic systems. We investigated the microbial colonisation and decomposition of plant litter along a fertility gradient, which varied in both pH and N availability in both soil and adjacent water. To do this we installed litterbags with birch (Betula pendula) in streams and corresponding soils in adjacent riparian areas in a boreal system, in Krycklan, Sweden. During the four months covering the ice-free growth season we monitored the successional dynamics of fungal (acetate incorporation into ergosterol) and bacterial growth (thymidine incorporation), microbial respiration in leaf litter, and quantitative and qualitative changes in litter over time. We observed that bacterial growth rates were initially higher in litter decomposing in streams than those in soils, but differences between terrestrial and aquatic bacterial production converged towards the end of the experiment. In litter bags installed in soils, bacterial growth was lower at sites with more acidic pH and lower N availability, while aquatic bacteria were relatively unaffected by the fertility level. Fungal growth rates were two-fold higher for litter decomposing in streams than in soils. In aquatic systems, fungal growth was initially lower in low fertility sites, but differences gradually disappeared over the time course. Fungal growth rates measured on litter-bags in soils were relatively stable over time, with unclear links to fertility. Microbial respiration rates were highest in litterbags buried in soils, and only initially negatively affected by pH. There was a large decrease in litter mass loss initially in aquatic systems. Subsequently the rates of loss stabilized to similar values to those in terrestrial systems, to finally be exceeded by the rates of loss in terrestrial systems. In conclusion, initial decomposition of litter appeared to be N-limited in aquatic systems, which was associated with a fungal dominance. In contrast, litter decomposition in terrestrial systems appeared to be lower in acidic sites, which coincided with lower growth rates of bacteria. Litter degradation was initially faster in aquatic systems, but overall mass-loss over the full time course was higher in terrestrial systems.

Design and Characterization of a Sensorized Microfluidic Cell-Culture System with Electro-Thermal Micro-Pumps and Sensors for Cell Adhesion, Oxygen, and pH on a Glass Chip.

PubMed

Bonk, Sebastian M; Stubbe, Marco; Buehler, Sebastian M; Tautorat, Carsten; Baumann, Werner; Klinkenberg, Ernst-Dieter; Gimsa, Jan

2015-07-30

We combined a multi-sensor glass-chip with a microfluidic channel grid for the characterization of cellular behavior. The grid was imprinted in poly-dimethyl-siloxane. Mouse-embryonal/fetal calvaria fibroblasts (MC3T3-E1) were used as a model system. Thin-film platinum (Pt) sensors for respiration (amperometric oxygen electrode), acidification (potentiometric pH electrodes) and cell adhesion (interdigitated-electrodes structures, IDES) allowed us to monitor cell-physiological parameters as well as the cell-spreading behavior. Two on-chip electro-thermal micro-pumps (ETμPs) permitted the induction of medium flow in the system, e.g., for medium mixing and drug delivery. The glass-wafer technology ensured the microscopic observability of the on-chip cell culture. Connecting Pt structures were passivated by a 1.2 μm layer of silicon nitride (Si3N4). Thin Si3N4 layers (20 nm or 60 nm) were used as the sensitive material of the pH electrodes. These electrodes showed a linear behavior in the pH range from 4 to 9, with a sensitivity of up to 39 mV per pH step. The oxygen sensors were circular Pt electrodes with a sensor area of 78.5 μm(2). Their sensitivity was 100 pA per 1% oxygen increase in the range from 0% to 21% oxygen (air saturated). Two different IDES geometries with 30- and 50-μm finger spacings showed comparable sensitivities in detecting the proliferation rate of MC3T3 cells. These cells were cultured for 11 days in vitro to test the biocompatibility, microfluidics and electric sensors of our system under standard laboratory conditions.

Developing A National Groundwater-Monitoring Network In Korea

NASA Astrophysics Data System (ADS)

Kim, N. J.; Cho, M. J.; Woo, N. C.

1995-04-01

Since the 1960's, the groundwater resources of Korea have been developed without a proper regulatory system for monitoring and preservation, resulting in significant source depletion, land subsidence, water contamination, and sea-water intrusion. With the activation of the "Groundwater Law" in June 1994, the government initiated a project to develop a groundwater-monitoring network to describe general groundwater quality, to define its long-term changes, and to identify major factors affecting changes in groundwater quality and yield. In selecting monitoring locations nationwide, criteria considered are 1) spatial distribution, 2) aquifer characteristics of hydrogeologic units, 3) local groundwater flow regime, 4) linkage with surface hydrology observations, 5) site accessibility, and 6) financial situations. A total of 310 sites in 78 small hydrologic basins were selected to compose the monitoring network. Installation of monitoring wells is scheduled to start in 1995 for 15 sites; the remainder are scheduled to be completed by 2001. At each site, a nest of monitoring wells was designed; shallow and deep groundwater will be monitored for water temperature, pH, EC, DO and TDS every month. Water-level fluctuations will also be measured by automatic recorders equipped with pressure transducers. As a next step, the government plans to develop a groundwater-database management system, which could be linked with surface hydrologic data.

Manipulation and measurement of pH sensitive metal-ligand binding using electrochemical proton generation and metal detection.

PubMed

Read, Tania L; Joseph, Maxim B; Macpherson, Julie V

2016-01-31

Generator-detector electrodes can be used to both perturb and monitor pH dependant metal-ligand binding equilibria, in situ. In particular, protons generated at the generator locally influence the speciation of metal (Cu(2+)) in the presence of ligand (triethylenetetraamine), with the detector employed to monitor, in real time, free metal (Cu(2+)) concentrations.

Bladder mucosa pH and Pco2 as a minimally invasive monitor of hemorrhagic shock and resuscitation.

PubMed

Clavijo-Alvarez, Julio A; Sims, Carrie A; Menconi, Michael; Shim, Inbo; Ochoa, Christian; Puyana, Juan Carlos

2004-12-01

Continuous monitoring of pH, Pco2, and Po2 using fiberoptic sensor technology has been proposed recently as a clinical monitor of the severity of shock and impaired tissue perfusion. Surrogates of gut tissue perfusion such as gastric tonometry, although cumbersome, have been used to indirectly quantify the degree of gut ischemia. The purpose of this study was to demonstrate the feasibility of monitoring bladder mucosa (BM) and to compare urinary bladder mucosa and proximal jejunum mucosa interstitial pH and Pco2 during hemorrhagic shock and resuscitation. Eleven male miniature swine (25-35 kg) (control, n = 4; shock, n = 7) underwent jejunal tonometry and cystostomy. A multisensor probe was placed adjacent to the BM. Urine was diverted. Normocarbia was maintained. Animals were hemorrhaged and kept at a mean arterial pressure of 40 mm Hg. When a constant infusion was required to maintain the mean arterial pressure at 40 mm Hg (decompensation), animals were resuscitated with shed blood plus two times the shed volume in lactated Ringer's solution (20 minutes) and observed for 2 hours. During decompensation, BM pH values decreased significantly from 7.33 +/- 0.08 to 7.01 +/- 0.2 (p < 0.01) and recovered to 7.11 +/- 0.19 at 120 minutes after completion of resuscitation. During decompensation, BM Pco2 values increased significantly compared with baseline (from 49 +/- 6 mm Hg to 71 +/- 19 mm Hg, p < 0.05) and returned to baseline with resuscitation. Jejunum mucosa and BM interstitial Pco2 correlated throughout shock and resuscitation (r = 0.49). Bland-Altman analysis demonstrated significant differences between jejunum mucosa (intramucosal pH) and BM interstitial pH. Shock-induced changes in the Pco2 of the BM are comparable to tonometric changes in the gut. These data suggest that continuous fiberoptic multisensor probe monitoring of the BM could potentially provide a minimally invasive method for the assessment of impaired tissue perfusion of the splanchnic circulation during shock and resuscitation.

Review on State-of-the-art in Polymer Based pH Sensors

PubMed Central

Korostynska, Olga; Arshak, Khalil; Gill, Edric; Arshak, Arousian

2007-01-01

This paper reviews current state-of-the-art methods of measuring pH levels that are based on polymer materials. These include polymer-coated fibre optic sensors, devices with electrodes modified with pH-sensitive polymers, fluorescent pH indicators, potentiometric pH sensors as well as sensors that use combinatory approach for ion concentration monitoring. PMID:28903277

[Space-time water monitoring system at the Iriklinsk hydroelectric power station].

PubMed

Deriabin, D G; Poliakov, E G; Priakhina, A A; Karimov, I F

2002-01-01

The Microbiosensor B 17677 F test system was applied to make a space-time monitoring of the biotoxicity of water used for production and everyday purposes at the Iriklinsk hydroelectric power station (IHEPS) and to identify the leading causes determining the biotoxicity of tested samples. There were seasonal variations in the biotoxicity with the maximum in spring and with minimum in winter and spring and a relationship of the spring rise in the biotoxicity to water pH changes. There was also an association of the certain values of the biotoxicity of industrial water with the concentration of petroleum products that are major pollutants at the IHEPS. The datum points that characterize the maximum level of technogenic exposure were identified.

Hapten-derivatized nanoparticle targeting and imaging of gene expression by multimodality imaging systems.

PubMed

Cheng, C-M; Chu, P-Y; Chuang, K-H; Roffler, S R; Kao, C-H; Tseng, W-L; Shiea, J; Chang, W-D; Su, Y-C; Chen, B-M; Wang, Y-M; Cheng, T-L

2009-01-01

Non-invasive gene monitoring is important for most gene therapy applications to ensure selective gene transfer to specific cells or tissues. We developed a non-invasive imaging system to assess the location and persistence of gene expression by anchoring an anti-dansyl (DNS) single-chain antibody (DNS receptor) on the cell surface to trap DNS-derivatized imaging probes. DNS hapten was covalently attached to cross-linked iron oxide (CLIO) to form a 39+/-0.5 nm DNS-CLIO nanoparticle imaging probe. DNS-CLIO specifically bound to DNS receptors but not to a control single-chain antibody receptor. DNS-CLIO (100 microM Fe) was non-toxic to both B16/DNS (DNS receptor positive) and B16/phOx (control receptor positive) cells. Magnetic resonance (MR) imaging could detect as few as 10% B16/DNS cells in a mixture in vitro. Importantly, DNS-CLIO specifically bound to a B16/DNS tumor, which markedly reduced signal intensity. Similar results were also shown with DNS quantum dots, which specifically targeted CT26/DNS cells but not control CT26/phOx cells both in vitro and in vivo. These results demonstrate that DNS nanoparticles can systemically monitor the expression of DNS receptor in vivo by feasible imaging systems. This targeting strategy may provide a valuable tool to estimate the efficacy and specificity of different gene delivery systems and optimize gene therapy protocols in the clinic.

Sensors and Biosensors for C-Reactive Protein, Temperature and pH, and Their Applications for Monitoring Wound Healing: A Review

PubMed Central

Dini, Valentina; Kirchhain, Arno; Janowska, Agata; Oranges, Teresa; Di Francesco, Fabio

2017-01-01

Wound assessment is usually performed in hospitals or specialized labs. However, since patients spend most of their time at home, a remote real time wound monitoring would help providing a better care and improving the healing rate. This review describes the advances in sensors and biosensors for monitoring the concentration of C-reactive protein (CRP), temperature and pH in wounds. These three parameters can be used as qualitative biomarkers to assess the wound status and the effectiveness of therapy. CRP biosensors can be classified in: (a) field effect transistors, (b) optical immunosensors based on surface plasmon resonance, total internal reflection, fluorescence and chemiluminescence, (c) electrochemical sensors based on potentiometry, amperometry, and electrochemical impedance, and (d) piezoresistive sensors, such as quartz crystal microbalances and microcantilevers. The last section reports the most recent developments for wearable non-invasive temperature and pH sensors suitable for wound monitoring. PMID:29257113

Accuracy of diagnosing gastroesophageal reflux disease by GerdQ, esophageal impedance monitoring and histology.

PubMed

Zhou, Li Ya; Wang, Ye; Lu, Jing Jing; Lin, Lin; Cui, Rong Li; Zhang, He Jun; Xue, Yan; Ding, Shi Gang; Lin, San Ren

2014-05-01

To assess the performance of self-assessment gastroesophageal reflux disease questionnaire (GerdQ), 24-h impedance monitoring, proton pump inhibitor (PPI) test and intercellular space of esophageal mucosal epithelial cells in the diagnosis of gastroesophageal reflux disease (GERD). Patients with symptoms suspected of GERD were administered the GerdQ and underwent endoscopy (measurement of intercellular space in the biopsy specimen sampling at 2 cm above the Z-line) and 24-h impedance pH monitoring, together with a 2-week experimental treatment with esomeprazole. A total of 636 patients were included for the final analysis, including 352 with GERD. The sensitivity and specificity of GerdQ and 24-h impedance monitoring for diagnosing GERD were 57.7% and 48.9%, and 66.4% and 43.3%, respectively. The sensitivity of 24-h impedance pH monitoring increased to 93.7%. The sensitivity and specificity of dilated intercellular spaces (DIS) (≥0.9 μm) for diagnosing GERD were 61.2% and 56.1%, respectively, whereas those for PPI test were 70.5% and 44.4%. GerdQ score or PPI test alone cannot accurately diagnose GERD in a Chinese population suspected of GERD. A definitive diagnosis of GERD still depends on endoscopy or 24-h pH monitoring. 24-h impedance pH monitoring may increase the sensitivity for diagnosing GERD by 20%; however, when used alone, it results in poor specificity in patients without acid suppressive therapy. © 2014 Chinese Medical Association Shanghai Branch, Chinese Society of Gastroenterology, Renji Hospital Affiliated to Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd.

Monitoring fetal electrocortical activity during labour for predicting worsening acidemia: a prospective study in the ovine fetus near term.

PubMed

Frasch, Martin G; Keen, Ashley E; Gagnon, Robert; Ross, Michael G; Richardson, Bryan S

2011-01-01

Severe fetal acidemia during labour with arterial pH below 7.00 is associated with increased risk of hypoxic-ischemic brain injury. Electronic fetal heart rate (FHR) monitoring, the mainstay of intrapartum surveillance, has poor specificity for detecting fetal acidemia. We studied brain electrical activity measured with electrocorticogram (ECOG) in the near term ovine fetus subjected to repetitive umbilical cord occlusions (UCO) inducing FHR decelerations, as might be seen in human labour, to delineate the time-course for ECOG changes with worsening acidemia and thereby assess the potential clinical utility of fetal ECOG. Ten chronically catheterized fetal sheep were studied through a series of mild, moderate and severe UCO until the arterial pH was below 7.00. At a pH of 7.24 ± 0.04, 52 ± 13 min prior to the pH dropping <7.00, spectral edge frequency (SEF) increased to 23 ± 2 Hz from 3 ± 1 Hz during each FHR deceleration (p<0.001) and was correlated to decreases in FHR and in fetal arterial blood pressure during each FHR deceleration (p<0.001). The UCO-related changes in ECOG occurred in advance of the pH decreasing below 7.00. These ECOG changes may be a protective mechanism suppressing non-essential energy needs when oxygen supply to the fetal brain is decreased acutely. By detecting such "adaptive brain shutdown," the need for delivery in high risk pregnant patients may be more accurately predicted than with FHR monitoring alone. Therefore, monitoring fetal electroencephalogram (EEG, the human equivalent of ECOG) during human labour may be a useful adjunct to FHR monitoring.

Monitoring Fetal Electrocortical Activity during Labour for Predicting Worsening Acidemia: A Prospective Study in the Ovine Fetus Near Term

PubMed Central

Frasch, Martin G.; Keen, Ashley E.; Gagnon, Robert; Ross, Michael G.; Richardson, Bryan S.

2011-01-01

Background Severe fetal acidemia during labour with arterial pH below 7.00 is associated with increased risk of hypoxic-ischemic brain injury. Electronic fetal heart rate (FHR) monitoring, the mainstay of intrapartum surveillance, has poor specificity for detecting fetal acidemia. We studied brain electrical activity measured with electrocorticogram (ECOG) in the near term ovine fetus subjected to repetitive umbilical cord occlusions (UCO) inducing FHR decelerations, as might be seen in human labour, to delineate the time-course for ECOG changes with worsening acidemia and thereby assess the potential clinical utility of fetal ECOG. Methodology/Principal Findings Ten chronically catheterized fetal sheep were studied through a series of mild, moderate and severe UCO until the arterial pH was below 7.00. At a pH of 7.24±0.04, 52±13 min prior to the pH dropping <7.00, spectral edge frequency (SEF) increased to 23±2 Hz from 3±1 Hz during each FHR deceleration (p<0.001) and was correlated to decreases in FHR and in fetal arterial blood pressure during each FHR deceleration (p<0.001). Conclusions/Significance The UCO-related changes in ECOG occurred in advance of the pH decreasing below 7.00. These ECOG changes may be a protective mechanism suppressing non-essential energy needs when oxygen supply to the fetal brain is decreased acutely. By detecting such “adaptive brain shutdown,” the need for delivery in high risk pregnant patients may be more accurately predicted than with FHR monitoring alone. Therefore, monitoring fetal electroencephalogram (EEG, the human equivalent of ECOG) during human labour may be a useful adjunct to FHR monitoring. PMID:21789218

Active Control of pH in the Bioculture System Through Carbon Dioxide Control

NASA Technical Reports Server (NTRS)

Monhollon, Luke; Pletcher, David; Hauss, Jessica

2016-01-01

For successful cell research, the growth culture environment must be tightly controlled. Deviance from the optimal conditions will mask the desired variable being analyzed or lead to inconstancies in the results. In standard laboratories, technology and procedures are readily available for the reliable control of variables such as temperature, pH, nutrient loading, and dissolved gases. Due to the nature of spaceflight, and the inherent constraints to engineering designs, these same elements become a challenge to maintain at stable values by both automated and manual approaches. Launch mass, volume, and power usage create significant constraints to cell culture systems; nonetheless, innovative solutions for active environmental controls are available. The acidity of the growth media cannot be measured through standard probes due to the degradation of electrodes and reliance on indicators for chromatography. Alternatively, carbon dioxide sensors are capable of monitoring the pH by leveraging the relationship between the partial pressure of carbon dioxide and carbonic acid in solution across a membrane. In microgravity cell growth systems, the gas delivery system can be used to actively maintain the media at the proper acidity by maintaining a suitable gas mixture around permeable tubing. Through this method, launch mass and volume are significantly reduced through the efficient use of the limited gas supply in orbit.

2D ratiometric fluorescent pH sensor for tracking of cells proliferation and metabolism.

PubMed

Ma, Jun; Ding, Changqin; Zhou, Jie; Tian, Yang

2015-08-15

Extracellular pH plays a vital role no matter in physiological or pathological studies. In this work, a hydrogel, CD@Nile-FITC@Gel (Gel sensor), entrapping the ratiometric fluorescent probe CD@Nile-FITC was developed. The Gel sensor was successfully used for real-time extracellular pH monitoring. In the case of CD@Nile-FITC, pH-sensitive fluorescent dye fluorescein isothiocyanate (FITC) was chosen as the response signal for H(+) and Nile blue chloride (Nile) as the reference signal. The developed fluorescent probe exhibited high selectivity for pH over other metal ions and amino acids. Meanwhile, the carbon-dots-based inorganic-organic probe demonstrated excellent photostability against long-term light illumination. In order to study the extracellular pH change in processes of cell proliferation and metabolism, CD@Nile-FITC probe was entrapped in sodium alginate gel and consequently formed CD@Nile-FITC@Gel. The MTT assay showed low cytotoxicity of the Gel and the pH titration indicated that it could monitor the pH fluctuations linearly and rapidly within the pH range of 6.0-9.0, which is valuable for physiological pH determination. As expected, the real-time bioimaging of the probe was successfully achieved. Copyright © 2015 Elsevier B.V. All rights reserved.

Quantitative imaging of rhizosphere pH and CO2 dynamics with planar optodes.

PubMed

Blossfeld, Stephan; Schreiber, Christina Maria; Liebsch, Gregor; Kuhn, Arnd Jürgen; Hinsinger, Philippe

2013-07-01

Live imaging methods have become extremely important for the exploration of biological processes. In particular, non-invasive measurement techniques are key to unravelling organism-environment interactions in close-to-natural set-ups, e.g. in the highly heterogeneous and difficult-to-probe environment of plant roots: the rhizosphere. pH and CO2 concentration are the main drivers of rhizosphere processes. Being able to monitor these parameters at high spatio-temporal resolution is of utmost importance for relevant interpretation of the underlying processes, especially in the complex environment of non-sterile plant-soil systems. This study introduces the application of easy-to-use planar optode systems in different set-ups to quantify plant root-soil interactions. pH- and recently developed CO2-sensors were applied to rhizobox systems to investigate roots with different functional traits, highlighting the potential of these tools. Continuous and highly resolved real-time measurements were made of the pH dynamics around Triticum turgidum durum (durum wheat) roots, Cicer arietinum (chickpea) roots and nodules, and CO2 dynamics in the rhizosphere of Viminaria juncea. Wheat root tips acidified slightly, while their root hair zone alkalized their rhizosphere by more than 1 pH unit and the effect of irrigation on soil pH could be visualized as well. Chickpea roots and nodules acidified the surrounding soil during N2 fixation and showed diurnal changes in acidification activity. A growing root of V. juncea exhibited a large zone of influence (mm) on soil CO2 content and therefore on its biogeochemical surrounding, all contributing to the extreme complexity of the root-soil interactions. This technique provides a unique tool for future root research applications and overcomes limitations of previous systems by creating quantitative maps without, for example, interpolation and time delays between single data points.

Monitoring the nitrification and identifying the endpoint of ammonium oxidation by using a novel system of titrimetry.

PubMed

Zhang, Xin; Zhang, Daijun; Lu, Peili; Bai, Cui; Xiao, Pengying

2011-01-01

Based on the structure of the hybrid respirometer previously developed in our group, a novel implementation for titrimetry was developed, in which two pH electrodes were installed at the inlet and outlet of the measuring cell. The software capable of digital filtering and titration time delay correction was developed in LabVIEW. The hardware and software of the titrimeter and the respirometer were integrated to construct a novel system of respirometry-titrimetry. The system was applied to monitor a batch nitrification process. The obtained profiles of oxygen uptake rate (OUR) and hydrogen ion production rate (HPR) are consistent with each other and agree with the principle of the biological nitrification reaction. According to the OUR and HPR measurements, the oxidized ammonium concentrations were estimated accurately. Furthermore, the endpoint of ammonium oxidation was identified with much higher sensitivity by the HPR measurement. The system could be potentially used for on-line monitoring of biochemical reactions occurring in any kind of bioreactors because its measuring cell is completely independent of the bioreactor.

Gastro-oesophageal reflux monitoring: review and consensus report on detection and definitions of acid, non-acid, and gas reflux

PubMed Central

Sifrim, D; Castell, D; Dent, J; Kahrilas, P J

2004-01-01

To date, most concepts on the frequency of gastro-oesophageal reflux episodes and the efficiency of the antireflux barrier have been based on inferences derived from measurement of oesophageal pH. The development of intraluminal impedance monitoring has highlighted the fact that pH monitoring does not detect all gastro-oesophageal reflux events when little or no acid is present in the refluxate, even if special pH tracing analysis criteria are used. In November 2002, a workshop took place at which 11 specialists in the field of gastro-oesophageal reflux disease discussed and criticised all currently available techniques for measurement of reflux. Here, a summary of their conclusions and recommendations of how to achieve the best results from the various techniques now available for reflux measurement is presented. PMID:15194656

Multifunctional Water Sensors for pH, ORP, and Conductivity Using Only Microfabricated Platinum Electrodes

PubMed Central

Lin, Wen-Chi; Brondum, Klaus; Monroe, Charles W.; Burns, Mark A.

2017-01-01

Monitoring of the pH, oxidation-reduction-potential (ORP), and conductivity of aqueous samples is typically performed using multiple sensors. To minimize the size and cost of these sensors for practical applications, we have investigated the use of a single sensor constructed with only bare platinum electrodes deposited on a glass substrate. The sensor can measure pH from 4 to 10 while simultaneously measuring ORP from 150 to 800 mV. The device can also measure conductivity up to 8000 μS/cm in the range of 10 °C to 50 °C, and all these measurements can be made even if the water samples contain common ions found in residential water. The sensor is inexpensive (i.e., ~$0.10/unit) and has a sensing area below 1 mm2, suggesting that the unit is cost-efficient, robust, and widely applicable, including in microfluidic systems. PMID:28753913

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

PubMed

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.

In Situ Monitoring of Pb2+ Leaching from the Galvanic Joint Surface in a Prepared Chlorinated Drinking Water.

PubMed

Ma, Xiangmeng; Armas, Stephanie M; Soliman, Mikhael; Lytle, Darren A; Chumbimuni-Torres, Karin; Tetard, Laurene; Lee, Woo Hyoung

2018-02-20

A novel method using a micro-ion-selective electrode (micro-ISE) technique was developed for in situ lead monitoring at the water-metal interface of a brass-leaded solder galvanic joint in a prepared chlorinated drinking water environment. The developed lead micro-ISE (100 μm tip diameter) showed excellent performance toward soluble lead (Pb 2+ ) with sensitivity of 22.2 ± 0.5 mV decade -1 and limit of detection (LOD) of 1.22 × 10 -6 M (0.25 mg L -1 ). The response time was less than 10 s with a working pH range of 2.0-7.0. Using the lead micro-ISE, lead concentration microprofiles were measured from the bulk to the metal surface (within 50 μm) over time. Combined with two-dimensional (2D) pH mapping, this work clearly demonstrated that Pb 2+ ions build-up across the lead anode surface was substantial, nonuniform, and dependent on local surface pH. A large pH gradient (ΔpH = 6.0) developed across the brass and leaded-tin solder joint coupon. Local pH decreases were observed above the leaded solder to a pH as low as 4.0, indicating it was anodic relative to the brass. The low pH above the leaded solder supported elevated lead levels where even small local pH differences of 0.6 units (ΔpH = 0.6) resulted in about four times higher surface lead concentrations (42.9 vs 11.6 mg L -1 ) and 5 times higher fluxes (18.5 × 10 -6 vs 3.5 × 10 -6 mg cm -2 s -1 ). Continuous surface lead leaching monitoring was also conducted for 16 h.

An Optical Sensor with Polyaniline-Gold Hybrid Nanostructures for Monitoring pH in Saliva.

PubMed

Luo, Chongdai; Wang, Yangyang; Li, Xuemeng; Jiang, Xueqin; Gao, Panpan; Sun, Kang; Zhou, Jianhua; Zhang, Zhiguang; Jiang, Qing

2017-03-17

Saliva contains important personal physiological information that is related to some diseases, and it is a valuable source of biochemical information that can be collected rapidly, frequently, and without stress. In this article, we reported a new and simple localized surface plasmon resonance (LSPR) substrate composed of polyaniline (PANI)-gold hybrid nanostructures as an optical sensor for monitoring the pH of saliva samples. The overall appearance and topography of the substrates, the composition, and the wettability of the LSPR surfaces were characterized by optical and scanning electron microscope (SEM) images, infrared spectra, and contact angles measurement, respectively. The PANI-gold hybrid substrate readily responded to the pH. The response time was very short, which was 3.5 s when the pH switched from 2 to 7, and 4.5 s from 7 to 2. The changes of visible-near-infrared (NIR) spectra of this sensor upon varying pH in solution showed that-for the absorption at given wavelengths of 665 nm and 785 nm-the sensitivities were 0.0299 a.u./pH (a.u. = arbitrary unit) with a linear range of pH = 5-8 and 0.0234 a.u./pH with linear range of pH = 2-8, respectively. By using this new sensor, the pH of a real saliva sample was monitored and was consistent with the parallel measurements with a standard laboratory method. The results suggest that this novel LSPR sensor shows great potential in the field of mobile healthcare and home medical devices, and could also be modified by different sensitive materials to detect various molecules or ions in the future.

The clinical value of pharyngeal pH monitoring using a double-probe, triple-sensor catheter in patients with laryngopharyngeal reflux.

PubMed

Muderris, Togay; Gokcan, M Kursat; Yorulmaz, Irfan

2009-02-01

To determine the clinical value of pharyngeal pH monitoring for the diagnosis of laryngopharyngeal reflux (LPR) by using a double-probe, triple-sensor catheter in patients with symptoms of LPR. Prospective review of pH values recorded at the pharyngeal sensor, with the sensor placed in the proximal esophagus in patients with suspected LPR. Tertiary care university hospital. Thirty-three consecutive patients with symptoms of LPR. A pH test result was considered abnormal if a single reflux episode was detected in the hypopharynx and if, in the proximal esophagus, the total percentage of time the pH value was below 4 was 1.0% or higher. Data obtained from sensors were compared to determine the validity of pharyngeal sensor. Correlation between patients' reflux finding scores, reflux finding indexes, and reflux episodes were analyzed. Of 33 patients, 17 had more than 1 reflux episode detected by the pharyngeal sensor and 19 had pathological reflux detected by the proximal esophageal sensor. Four patients who had pharyngeal reflux had a normal esophageal acid exposure time, and 6 patients who had pathological reflux detected by the proximal esophageal sensor did not experienced any pharyngeal reflux episode. Four patients would have had a false-negative test result and 6 subjects would have had a false-positive test result if a hypopharyngeal pH sensor was not implemented. The adjustable, bifurcated, triple-sensor pH probe allows identifying true hypopharyngeal reflux episodes. If single-probe, double-sensor pH monitoring is to be performed, the proximal probe should be placed in the pharynx, not in the upper esophagus.

From municipal sewage to drinking water: fate and removal of pharmaceutical residues in the aquatic environment in urban areas.

PubMed

Heberer, Th; Reddersen, K; Mechlinski, A

2002-01-01

Recently, the occurrence and fate of pharmaceutically active compounds (PhACs) in the aquatic environment was recognized as one of the emerging issues in environmental chemistry and as a matter of public concern. Residues of PhACs have been found as contaminants in sewage, surface, and ground- and drinking water samples. Since June 2000, a new long-term monitoring program of sewage, surface, ground- and drinking water has been carried out in Berlin, Germany. Samples, collected periodically from selected sites in the Berlin area, are investigated for residues of PhACs and related contaminants. The purpose of this monitoring is to investigate these compounds over a long time period to get more reliable data on their occurrence and fate in the different aquatic compartments. Moreover, the surface water investigations allow the calculation of season-dependent contaminant loads in the Berlin waters. In the course of the monitoring program, PhACs and some other polar compounds were detected at concentrations up to the microg/L-level in all compartments of the Berlin water cycle. The monitoring is accompanied and supported by several other investigations such as laboratory column experiments and studies on bank filtration and drinking water treatment using conventional or membrane filtration techniques.

Insights into accelerated liposomal release of topotecan in plasma monitored by a non-invasive fluorescence spectroscopic method

PubMed Central

Fugit, Kyle D.; Jyoti, Amar; Upreti, Meenakshi; Anderson, Bradley D.

2014-01-01

A non-invasive fluorescence method was developed to monitor liposomal release kinetics of the anticancer agent topotecan (TPT) in physiological fluids and subsequently used to explore the cause of accelerated release in plasma. Analyses of fluorescence excitation spectra confirmed that unencapsulated TPT exhibits a red shift in its spectrum as pH is increased. This property was used to monitor TPT release from actively loaded liposomal formulations having a low intravesicular pH. Mathematical release models were developed to extract reliable rate constants for TPT release in aqueous solutions monitored by fluorescence and release kinetics obtained by HPLC. Using the fluorescence method, accelerated TPT release was observed in plasma as previously reported in the literature. Simulations to estimate the intravesicular pH were conducted to demonstrate that accelerated release correlated with alterations in the low intravesicular pH. This was attributed to the presence of ammonia in plasma samples rather than proteins and other plasma components generally believed to alter release kinetics in physiological samples. These findings shed light on the critical role that ammonia may play in contributing to the preclinical/clinical variability and performance seen with actively-loaded liposomal formulations of TPT and other weakly-basic anticancer agents. PMID:25456833

Application of Iron Oxide as a pH-dependent Indicator for Improving the Nutritional Quality

PubMed Central

2016-01-01

Acid food indicators can be used as pH indicators for evaluating the quality and freshness of fermented products during the full course of distribution. Iron oxide particles are hardly suspended in water, but partially or completely agglomerated. The agglomeration degree of the iron oxide particles depends on the pH. The pH-dependent particle agglomeration or dispersion can be useful for monitoring the acidity of food. The zeta potential of iron oxide showed a decreasing trend as the pH increased from 2 to 8, while the point of zero charge (PZC) was observed around at pH 6.0-7.0. These results suggested that the size of the iron oxide particles was affected by the change in pH levels. As a result, the particle sizes of iron oxide were smaller at lower pH than at neutral pH. In addition, agglomeration of the iron oxide particles increased as the pH increased from 2 to 7. In the time-dependent aggregation test, the average particle size was 730.4 nm and 1,340.3 nm at pH 2 and 7, respectively. These properties of iron oxide particles can be used to develop an ideal acid indicator for food pH and to monitor food quality, besides a colorant or nutrient for nutrition enhancement and sensory promotion in food industry. PMID:27482521

Embedded micro-sensor for monitoring pH in concrete structures

NASA Astrophysics Data System (ADS)

Srinivasan, Rengaswamy; Phillips, Terry E.; Bargeron, C. Brent; Carlson, Micah A.; Schemm, Elizabeth R.; Saffarian, Hassan M.

2000-04-01

Three major causes of corrosion of steel in concrete are chloride ions (Cl-), temperature (T) and acidity (pH). Under normal operating temperatures and with pH above 13, steel does not undergo pitting corrosion. In presence of Cl-, if the pH decreases below 12, the probability of pitting increases. Acid rain and atmospheric carbon dioxide cause the pH to drop in concrete, often leading to corrosion of the structure with the concomitant cost of repair or replacement. Currently, the pH level in concrete is estimated through destructive testing of the structures. Glass ISFET, and other pH sensors that need maintenance and calibration cannot be embedded in concrete. In this paper, we describe an inexpensive solid state pH sensor that can be embedded in concrete, to detect pH changes at the early stages. It employs a chemical reagent, trinitrobenzenesulfonic acid (TNBS) that exhibits changes in optical properties in the 12 - 14 pH range, and is held in a film of a sol-gel/TNBS composite on an optically transparent surface. A simple LED/filter/photodiode transducer monitors pH-induced changes in TNBS. Such a device needs no periodic calibration or maintenance. The optical window, the light-source and sensor can be easily housed and encapsulated in a chemically inert structure, and embedded in concrete.

The Contribution of Command and Control to Unity of Effort

DTIC Science & Technology

2002-09-01

Engineering and Evaluation Centre University of South Australia Mawson Lakes, South Australia Author contact: 6 Frank Street St Morris SA 5068... Mawson Lakes, South Australia, , 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S...Noel Sproles PhD Systems Engineering and Evaluation Centre University of South Australia Mawson Lakes, South Australia While joint and multi-national

A Gold Nanoparticle Bio-Optical Transponder to Dynamically Monitor Intracellular pH.

PubMed

Carnevale, Kate J F; Riskowski, Ryan A; Strouse, Geoffrey F

2018-06-13

A pH-sensitive bio-optical transponder (pH-BOT) capable of simultaneously reporting the timing of intracellular DNA cargo release from a gold nanoparticle (AuNP) and the evolving intracellular pH (pH i) during endosomal maturation is demonstrated. The pH-BOT is designed with a triple-dye-labeled duplex DNA appended to a 6.6 nm AuNP, utilizing pH-responsive fluorescein paired with DyLight405 as a surface energy transfer (SET) coupled dye pair to ratiometrically report the pH at and after cargo release. A non-SET-coupled dye, DyLight 700, is used to provide dynamic tracking throughout the experiment. The pH-BOT beacon of the cargo uptake, release, and processing was visualized using live-cell confocal fluorescent microscopy in Chinese hamster ovary cells, and it was observed that while maturation of endosomes carrying pH-BOT is slowed significantly, the pH-BOT is distributed throughout the endolysosomal system while remaining at pH ∼6. This observed decoupling of endosomal maturation from acidification lends support to those models that propose that pH alone is not sufficient to explain endosomal maturation and may enable greater insight into our understanding of the fundamental processes of biology.

The potential of high intensity focused ultrasound (HIFU) combine phase-sensitive optical coherence tomography (PhS-OCT) for diseases diagnosis, treatment and monitoring

NASA Astrophysics Data System (ADS)

Zhou, Kanheng; Wang, Yan; Feng, Kairui; Li, Chunhui; Huang, Zhihong

2018-02-01

HIFU is a truly noninvasive, acoustic therapeutic technique that utilizes high intensity acoustic field in the focus to kill the targeted tissue for disease treatment purpose. The mechanical properties of targeted tissue changes before and after treatment, and this change can be accurately detected by shear wave elastography. Hence, shear wave elastography is usually used for monitoring HIFU treatment asynchronously. To improve the low spatial resolution in ultrasound shear wave elastography, and to perform diseases diagnosis, treatment and monitoring in the same system, a new setup that combines HIFU and PhS-OCT system was proposed in this study. This proposed setup could do 1) HIFU treatment when the transducer works at high energy level, 2) ultrasound induced shear wave optical coherence elastography for HIFU treatment asynchronous monitoring when the transducer works at low energy level. Ex-vivo bovine liver tissue was treated at the same energy level for different time (0s, 1s, 5s, 9s) in this research. Elastography was performed on the lesion area of the sample after HIFU treatment, and the elastogram was reconstructed by the time of flight time method. The elastogram results clearly show the boundary of HIFU lesion area and surrounding normal tissue, even for 1s treatment time. And the average elasticity of the lesion grows linearly as the treatment time increases. Combined with OCT needle probe, the proposed method has a large potential not only to be used for superficial diseases treatment, but also to be used for high-precision-demanded diseases treatment, e.g. nervous disease treatment.

Expert Water Quality Panel Review of Responses to the NASA Request for Information for the International Space Station On-Board Environmental Monitoring System

NASA Technical Reports Server (NTRS)

Fishman, Julianna L.; Mudgett, Paul D.; Packham, Nigel J.; Schultz, John R.; Straub, John E., II

2005-01-01

On August 9, 2003, NASA, with the cooperative support of the Vehicle Office of the International Space Station Program, the Advanced Human Support Technology Program, and the Johnson Space Center Habitability and Environmental Factors Office released a Request for Information, or RFI, to identify next-generation environmental monitoring systems that have demonstrated ability or the potential to meet defined requirements for monitoring air and water quality onboard the International Space Station. This report summarizes the review and analysis of the proposed solutions submitted to meet the water quality monitoring requirements. Proposals were to improve upon the functionality of the existing Space Station Total Organic Carbon Analyzer (TOCA) and monitor additional contaminants in water samples. The TOCA is responsible for in-flight measurement of total organic carbon, total inorganic carbon, total carbon, pH, and conductivity in the Space Station potable water supplies. The current TOCA requires hazardous reagents to accomplish the carbon analyses. NASA is using the request for information process to investigate new technologies that may improve upon existing capabilities, as well as reduce or eliminate the need for hazardous reagents. Ideally, a replacement for the TOCA would be deployed in conjunction with the delivery of the Node 3 water recovery system currently scheduled for November 2007.

Modified spectrophotometer for multi-dimensional circular dichroism/fluorescence data acquisition in titration experiments: application to the pH and guanidine-HCI induced unfolding of apomyoglobin.

PubMed

Ramsay, G; Ionescu, R; Eftink, M R

1995-08-01

In a previous paper (Ramsay and Eftink, Biophys. J. 66:516-523) we reported the development of a modified spectrophotometer that can make nearly simultaneous circular dichroism (CD) and fluorescence measurements. This arrangement allows multiple data sets to be collected during a single experiment, resulting in a saving of time and material, and improved correlation between the different types of measurements. The usefulness of the instrument was shown by thermal melting experiments on several different protein systems. This CD/fluorometer spectrophotometer has been further modified by interfacing with a syringe pump and a pH meter. This arrangement allows ligand, pH, and chemical denaturation titration experiments to be performed while monitoring changes in the sample's CD, absorbance, fluorescence, and light scattering properties. Our data acquisition program also has an ability to check whether the signals have approached equilibrium before the data is recorded. For performing pH titrations we have developed a procedure which uses the signal from a pH meter in a feedback circuit in order to collect data at evenly spaced pH intervals. We demonstrate the use of this instrument with studies of the unfolding of sperm whale apomyoglobin, as induced by acid pH and by the addition of guanidine-HCI.

Modified spectrophotometer for multi-dimensional circular dichroism/fluorescence data acquisition in titration experiments: application to the pH and guanidine-HCI induced unfolding of apomyoglobin.

PubMed Central

Ramsay, G; Ionescu, R; Eftink, M R

1995-01-01

In a previous paper (Ramsay and Eftink, Biophys. J. 66:516-523) we reported the development of a modified spectrophotometer that can make nearly simultaneous circular dichroism (CD) and fluorescence measurements. This arrangement allows multiple data sets to be collected during a single experiment, resulting in a saving of time and material, and improved correlation between the different types of measurements. The usefulness of the instrument was shown by thermal melting experiments on several different protein systems. This CD/fluorometer spectrophotometer has been further modified by interfacing with a syringe pump and a pH meter. This arrangement allows ligand, pH, and chemical denaturation titration experiments to be performed while monitoring changes in the sample's CD, absorbance, fluorescence, and light scattering properties. Our data acquisition program also has an ability to check whether the signals have approached equilibrium before the data is recorded. For performing pH titrations we have developed a procedure which uses the signal from a pH meter in a feedback circuit in order to collect data at evenly spaced pH intervals. We demonstrate the use of this instrument with studies of the unfolding of sperm whale apomyoglobin, as induced by acid pH and by the addition of guanidine-HCI. Images FIGURE 2 PMID:8527683

An application of second-order UV-derivative spectrophotometry for study of solvolysis of a novel fluocinolone acetonide ester

NASA Astrophysics Data System (ADS)

Markovic, Bojan; Vladimirov, Sote; Cudina, Olivera; Savic, Vladimir; Karljikovic-Rajic, Katarina

2010-02-01

A novel topical corticosteroid FA-21-PhP, 2-phenoxypropionate ester of fluocinolone acetonide, has been synthesized in order to investigate the possibility of decreasing systemic side effects. In this study model system for in vitro solvolytic reaction of FA-21-PhP has been analyzed in ethanol/water (90:10, v/v) with excess of sodium hydrogen carbonate. The selected conditions have been used as in vitro model for activation of corticosteroid C-21 ester prodrug. The second-order derivative spectrophotometric method (DS) using zero-crossing technique was developed for monitoring ternary mixture of solvolysis. Fluocinolone acetonide (FA) as a solvolyte was determined in the mixture in the concentration range 0.062-0.312 mM using amplitude 2D 274.96. Experimentally determined LOD value was 0.0295 mM. The accuracy of proposed DS method was confirmed with HPLC referent method. Peak area of parent ester FA-21-PhP was used for solvolysis monitoring to ensure the initial stage of changes. Linear relationship in HPLC assay for parent ester was obtained in the concentration range 0.054-0.54 mM, with experimentally determined LOD value of 0.0041 mM. Investigated solvolytic reaction in the presence of excess of NaHCO 3 proceeded via a pseudo-first-order kinetic with significant correlation coefficients 0.9891 and 0.9997 for DS and HPLC, respectively. The values of solvolysis rate constant calculated according to DS and HPLC methods are in good accordance 0.038 and 0.043 h -1, respectively.

Model-based pH monitor for sensor assessment.

PubMed

van Schagen, Kim; Rietveld, Luuk; Veersma, Alex; Babuska, Robert

2009-01-01

Owing to the nature of the treatment processes, monitoring the processes based on individual online measurements is difficult or even impossible. However, the measurements (online and laboratory) can be combined with a priori process knowledge, using mathematical models, to objectively monitor the treatment processes and measurement devices. The pH measurement is a commonly used measurement at different stages in the drinking water treatment plant, although it is a unreliable instrument, requiring significant maintenance. It is shown that, using a grey-box model, it is possible to assess the measurement devices effectively, even if detailed information of the specific processes is unknown.

Development of an On-animal Separation-based Sensor for Monitoring Drug Metabolism in Freely Roaming Sheep

PubMed Central

Scott, David E.; Willis, Sean D.; Gabbert, Seth; Johnson, Dave A.; Naylor, Erik; Janle, Elsa M.; Krichevsky, Janice E.; Lunte, Craig E.; Lunte, Susan M.

2015-01-01

The development of an on-animal separation-based sensor that can be employed for monitoring drug metabolism in a freely roaming sheep is described. The system consists of microdialysis sampling coupled directly to microchip electrophoresis with electrochemical detection (MD-ME-EC). Separations were accomplished using an all-glass chip with integrated platinum working and reference electrodes. Discrete samples from the microdialysis flow were introduced into the electrophoresis chip using a flow-gated injection approach. Electrochemical detection was accomplished in-channel using a two-electrode isolated potentiostat. Nitrite was separated by microchip electrophoresis using reverse polarity and a run buffer consisting of 50 mM phosphate at pH 7.4. The entire system was under telemetry control. The system was first tested with rats to monitor the production of nitrite following introduction of nitroglycerin into the subdermal tissue using a linear probe. The data acquired using the on-line MD-ME-EC system was compared to that obtained off-line analysis by liquid chromatography with electrochemical detection (LC-EC), using a second microdialysis probe implanted parallel to the first probe in the same animal. The MD-ME-EC device was then used on-animal to monitor the subdermal metabolism of nitroglycerin in sheep. The ultimate goal is to use this device to simultaneously monitor drug metabolism and behavior in a freely roaming animal. PMID:25697221

Physiological effects of pH gradients on Escherichia coli during plasmid DNA production.

PubMed

Cortés, José T; Flores, Noemí; Bolívar, Francisco; Lara, Alvaro R; Ramírez, Octavio T

2016-03-01

A two-compartment scale-down system was used to mimic pH heterogeneities that can occur in large-scale bioreactors. The system consisted of two interconnected stirred tank reactors (STRs) where one of them represented the conditions of the bulk of the fluid and the second one the zone of alkali addition for pH control. The working volumes ratio of the STRs was set to 20:1 in order to simulate the relative sizes of the bulk and alkali addition zones, respectively, in large-scale bioreactors. Residence times (tR ) in the alkali addition STR of 60, 120, 180, and 240 s were simulated during batch cultures of an engineered Escherichia coli strain that produced plasmid DNA (pDNA). pH gradients of up to 0.9 units, between the two compartments, were attained. The kinetic, stoichiometric, and pDNA topological changes due to the pH gradients were studied and compared to cultures at constant pH of 7.2 and 8.0. As the tR increased, the pDNA and biomass yields, as well as pDNA final titer decreased, whereas the accumulation of organic acids increased. Furthermore, the transcriptional response of 10 selected genes to alkaline stress (pH 8.0) and pH gradients was monitored at different stages of the cultures. The selected genes coded for ion transporters, amino acids catabolism enzymes, and transcriptional regulators. The transcriptional response of genes coding for amino acids catabolism, in terms of relative transcription level and stage of maximal expression, was different when the alkaline stress was constant or transient. This suggests the activation of different mechanisms by E. coli to cope with pH fluctuations compared to constant alkaline pH. Moreover, the transcriptional response of genes related to negative control of DNA synthesis did not correlate with the lower pDNA yields. This is the first study that reports the effects of pH gradients on pDNA production by E. coli cultures. The information presented can be useful for the design of better bioreactor scale-up strategies. © 2015 Wiley Periodicals, Inc.

Fluorescent Probes for Sensitive and Selective Detection of pH Changes in Live Cells in Visible and Near-infrared Channels.

PubMed

Fang, Mingxi; Adhikari, Rashmi; Bi, Jianheng; Mazi, Wafa; Dorh, Nethaniah; Wang, Jianbo; Conner, Nathan; Ainsley, Jon; Karabencheva-Christova, Tatyana G; Luo, Fen-Tair; Tiwari, Ashutosh; Liu, Haiying

2017-12-28

We report five fluorescent probes based on coumarin-hybridized fluorescent dyes with spirolactam ring structures (A-E) to detect pH changes in live cell by monitoring visible and near-infrared fluorescence changes. Under physiological or basic conditions, the fluorescent probes A, B, C, D and E preserve their spirolactam ring-closed forms and only display fluorescent peaks in the visible region corresponding to coumarin moieties at 497, 483, 498, 497 and 482 nm, respectively. However, at acidic pH, the rings of the spirolactam forms of the fluorescent probes A, B, C, D and E open up, generating new near-infrared fluorescence peaks at 711, 696, 707, 715, and 697 nm, respectively, through significantly extended π-conjugation to coumarin moieties of the fluorophores. The fluorescent probes B and E can be applied to visualize pH changes by monitoring visible as well as near-infrared fluorescence changes. This helps avoid fluorescence imaging blind spots at neutral or basic pH, which typical pH fluorescent probes encounter. The probes exhibit high sensitivity to pH changes, excellent photostability, low auto-fluorescence background and good cell membrane permeability.

Research notes : the pH of water in contact with fresh concrete.

DOT National Transportation Integrated Search

2003-02-01

Fresh concrete can significantly change the pH of water. To study the impacts, the pH of a few drilled shaft pours on Bear Creek near Zigzag (US Highway 26, MP 42.6) were monitored in order to aid discussion on future similar work. The concrete was p...

A study of pH-dependence of shrink and stretch of tetrahedral DNA nanostructures.

PubMed

Wang, Ping; Xia, Zhiwei; Yan, Juan; Liu, Xunwei; Yao, Guangbao; Pei, Hao; Zuo, Xiaolei; Sun, Gang; He, Dannong

2015-04-21

We monitored the shrink and stretch of the tetrahedral DNA nanostructure (TDN) and the i-motif connected TDN structure at pH 8.5 and pH 4.5, and we found that not only the i-motif can change its structure when the pH changes, but also the TDN and the DNA double helix change their structures when the pH changes.

Microchamber arrays with an integrated long luminescence lifetime pH sensor.

PubMed

Poehler, Elisabeth; Pfeiffer, Simon A; Herm, Marc; Gaebler, Michael; Busse, Benedikt; Nagl, Stefan

2016-04-01

A pH probe with a microsecond luminescence lifetime was obtained via covalent coupling of 6-carboxynaphthofluorescein (CNF) moieties to ruthenium-tris-(1,10-phenanthroline)(2+). The probe was covalently attached to amino-modified poly-(2-hydroxyethyl)methacrylate (pHEMA) and showed a pH-dependent FRET with luminescence lifetimes of 681 to 1260 ns and a working range from ca. pH 6.5 to 9.0 with a pKa of 7.79 ± 0.14. The pH sensor matrix was integrated via spin coating as ca. 1- to 2-μm-thick layer into "CytoCapture" cell culture dishes of 6 mm in diameter. These contained a microcavity array of square-shaped regions of 40 μm length and width and 15 μm depth that was homogeneously coated with the pH sensor matrix. The sensor layer showed fast response times in both directions. A microscopic setup was developed that enabled imaging of the pH inside the microchamber arrays over many hours. As a proof of principle, we monitored the pH of Escherichia coli cell cultures grown in the microchamber arrays. The integrated sensor matrix allowed pH monitoring spatially resolved in every microchamber, and the differences in cell growth between individual chambers could be resolved and quantified.

pH-responsiveness of multilayered films and membranes made of polysaccharides

PubMed Central

Silva, Joana M.; Caridade, Sofia G.; Costa, Rui R.; Alves, Natália M.; Groth, Thomas; Picart, Catherine; Reis, Rui L.; Mano, João F.

2016-01-01

We investigated the pH-dependent properties of multilayered films made of chitosan (CHI) and alginate (ALG) and focused on their post-assembly response to different pH environments using quartz crystal microbalance with dissipation monitoring (QCM-D), swelling studies, zeta potential measurements and dynamic mechanical analysis (DMA). In an acidic environment, the multilayers presented lower dissipation values and, consequently, higher moduli when compared with the values obtained for the pH used during the assembly (5.5). When the multilayers were exposed to alkaline environments the opposite behavior occurred. These results were further corroborated with the ability of this multilayered system to exhibit a reversible swelling-deswelling behavior within the pH range from 3 to 9. The changes of the physicochemical properties of the multilayer system were gradual and different from the ones of individual solubilized polyelectrolytes. This behavior is related to electrostatic interactions between the ionizable groups combined with hydrogen-bonding and hydrophobic interactions. Beyond the pH range of 3-9 the multilayers were stabilized by genipin cross-linking. The multilayered films also became more rigid while preserving the pH-responsiveness conferred by the ionizable moieties of the polyelectrolytes. This work demonstrates the versatility and feasibility of LbL methodology to generate inherently pH stimuli-responsive nanostructured films. Surface functionalization using pH-repsonsiveness endows abilities for several biomedical applications such as drug delivery, diagnostics, microfluidics, biosensing or biomimetic implantable membranes. PMID:26421873

Transcriptomic responses to ocean acidification in larval sea urchins from a naturally variable pH environment.

PubMed

Evans, Tyler G; Chan, Francis; Menge, Bruce A; Hofmann, Gretchen E

2013-03-01

Some marine ecosystems already experience natural declines in pH approximating those predicted with future anthropogenic ocean acidification (OA), the decline in seawater pH caused by the absorption of atmospheric CO2 . The molecular mechanisms that allow organisms to inhabit these low pH environments, particularly those building calcium carbonate skeletons, are unknown. Also uncertain is whether an enhanced capacity to cope with present day pH variation will confer resistance to future OA. To address these issues, we monitored natural pH dynamics within an intertidal habitat in the Northeast Pacific, demonstrating that upwelling exposes resident species to pH regimes not predicted to occur elsewhere until 2100. Next, we cultured the progeny of adult purple sea urchins (Strongylocentrotus purpuratus) collected from this region in CO2 -acidified seawater representing present day and near future ocean scenarios and monitored gene expression using transcriptomics. We hypothesized that persistent exposure to upwelling during evolutionary history will have selected for increased pH tolerance in this population and that their transcriptomic response to low pH seawater would provide insight into mechanisms underlying pH tolerance in a calcifying species. Resulting expression patterns revealed two important trends. Firstly, S. purpuratus larvae may alter the bioavailability of calcium and adjust skeletogenic pathways to sustain calcification in a low pH ocean. Secondly, larvae use different strategies for coping with different magnitudes of pH stress: initiating a robust transcriptional response to present day pH regimes but a muted response to near future conditions. Thus, an enhanced capacity to cope with present day pH variation may not translate into success in future oceans. © 2013 Blackwell Publishing Ltd.

In-Situ pH Measurements in Mid-Ocean Ridge Hydrothermal Vent Fluids: Constraints on Subseafloor Alteration Processes at Crustal Depths

NASA Astrophysics Data System (ADS)

Schaen, A. T.; Ding, K.; Seyfried, W. E.

2013-12-01

Developments in electrochemistry and material science have facilitated the construction of ceramic (YSZ) based chemical sensor systems that can be used to measure and monitor pH and redox in aqueous fluids at elevated temperatures and pressures. In recent years, these sensor systems have been deployed to acquire real-time and time series in-situ data for high-temperature hydrothermal vent fluids at the Main Endeavour Field (Juan de Fuca Ridge), 9oN (East Pacific Rise), and at the ultramafic-hosted Rainbow field (36oN, Mid-Atlantic Ridge). Here we review in-situ pH data measured at these sites and apply these data to estimate the pH of fluids ascending to the seafloor from hydrothermal alteration zones deeper in the crust. In general, in-situ pH measured at virtually all vent sites is well in excess of that measured shipboard owing to the effects of temperature on the distribution of aqueous species and the solubility of metal sulfides, especially Cu and Zn, originally dissolved in the vent fluids. In situ pH measurements determined at MEF (Sully vent) and EPR 9oN (P-vent) in 2005 and 2008 were 4.4 ×0.02 and 5.05×0.05, respectively. The temperature and pressure (seafloor) of the vent fluids at each of the respective sites were 356oC and 220 bar, and 380oC and 250 bar. Plotting these data with respect to fluid density reveals that the in-situ pH of each vent fluid is approximately 1.5 pH units below neutrality. The density-pH (in-situ) correlation, however, is important because it provides a means from which the vent fluids were derived. Using dissolved silica and chloride from fluid samples at the MEF (Sully) suggest T/P conditions of approximately 435oC, 380 bar, based on quartz-fluid and NaCl-H2O systems. At the fluid density calculated for these conditions, pH (in-situ) is predicted to be ~6.2. Attempts are presently underway to assess the effect of the calculated pH on metal sulfide and silicate (e.g., plagioclase, chlorite) solubility in comparison with constraints imposed by the full range of chemical components in the vent fluids sampled and analyzed in association with pH (in-situ) measurements. Since pH is a master variable in all geochemical systems, the novel approach proposed here may provide new insight on hydrothermal alteration processes at conditions difficult or impossible to assess by more traditional means, ultimately influencing hydrothermal fluid fluxes.

Hand-held monitor of sympathetic nervous system using salivary amylase activity and its validation by driver fatigue assessment.

PubMed

Yamaguchi, Masaki; Deguchi, Mitsuo; Wakasugi, Junichi; Ono, Shin; Takai, Noriyasu; Higashi, Tomoyuki; Mizuno, Yasufumi

2006-01-15

In order to realize a hand-held monitor of the sympathetic nervous system, we fabricated a completely automated analytical system for salivary amylase activity using a dry-chemistry system. This was made possible by the fabrication of a disposable test-strip equipped with built-in collecting and reagent papers and an automatic saliva transfer device. In order to cancel out the effects of variations in environmental temperature and pH of saliva, temperature- and pH-adjusted equations were experimentally determined, and each theoretical value was input into the memory of the hand-held monitor. Within a range of salivary amylase activity between 10 and 140 kU/l, the calibration curve for the hand-held monitor showed a coefficient with R(2)=0.97. Accordingly, it was demonstrated that the hand-held monitor enabled a user to automatically measure the salivary amylase activity with high accuracy with only 30 microl sample of saliva within a minute from collection to completion of the measurement. In order to make individual variations of salivary amylase activity negligible during driver fatigue assessment, a normalized equation was proposed. The normalized salivary amylase activity correlated with the mental and physical fatigue states. Thus, this study demonstrated that an excellent hand-held monitor with an algorithm for normalization of individuals' differences in salivary amylase activity, which could be easily and quickly used for evaluating the activity of the sympathetic nervous system at any time. Furthermore, it is suggested that the salivary amylase activity might be used as a better index for psychological research.

[Association between acid reflux and esophageal dysmotility in patients with gastroesophageal reflux disease].

PubMed

Yi, Zhi-hui; Feng, Li; Wen, Mao-yao; Liu, Jian-rong; Yang, Li

2014-05-01

To investigate the association between esophageal motility and acid reflux in patients with gastroesophageal reflux disease (GERD). A total of 94 patients with typical reflux symptoms such as heartburn, regurgitation and chest pain, whose score (Sc) of reflux diagnostic questionnaire (RDQ) was greater than or equal to 12 were enrolled in the study. Each participant was evaluated by upper gastrointestinal endoscopy, high resolution manometry (HRM) of esophagus and 24 h esophageal pH monitoring. The participants were divided into groups of reflux esophagitis (RE) and non-erosive reflux disease (NERD) on the basis of endoscopy findings. The 24 h esophageal pH monitoring categorized participants into physiologic reflux (pH) and pathologic reflux (pH+). The characteristics of esophageal motility and acid reflux were compared between the two groups of participants. Lower but non-significant differences (P > 0.05) were found in pressure of lower esophageal sphincter (LESP), length of lower esophageal sphincter (LESL), esophageal contraction amplitude (CA), distal contractile integral (DCI) and effective peristalsis proportion (EPP) in the participants in the RE group compared with those in the NERD group. Participants in the RE group had significantly higher prevalence of reduced LESP (63.0% vs. 31.7%, P < 0.01) and hiatus hernia (HH) (37.0% vs. 14.3%, P < 0.05) than those in the NERD group, pH+ was more prevalent in the RE group than in the NERD group (63.0% vs. 17.5%, P < 0.01). Indicators of 24 h esophageal pH monitoring were significantly higher in participants in the RE group compared with those in the NERD group (P < 0.05). Participants with pH+ had significantly lower LESP, CA and higher HH and prevalence of reduced LESP compared with those with pH (P < 0.05). LESL, DCI and EPP were lower in those with pH+ compared with those with pH-, but without statistical significance (P > 0.05). RE is closely associated with acid reflux and hiatus hernia. Esophageal dysmotility is more likely to appear in patients with pH+. The interaction of acid reflux and esophageal dysmotility may play a role in GERD.

Fast and Accurate Exhaled Breath Ammonia Measurement

PubMed Central

Solga, Steven F.; Mudalel, Matthew L.; Spacek, Lisa A.; Risby, Terence H.

2014-01-01

This exhaled breath ammonia method uses a fast and highly sensitive spectroscopic method known as quartz enhanced photoacoustic spectroscopy (QEPAS) that uses a quantum cascade based laser. The monitor is coupled to a sampler that measures mouth pressure and carbon dioxide. The system is temperature controlled and specifically designed to address the reactivity of this compound. The sampler provides immediate feedback to the subject and the technician on the quality of the breath effort. Together with the quick response time of the monitor, this system is capable of accurately measuring exhaled breath ammonia representative of deep lung systemic levels. Because the system is easy to use and produces real time results, it has enabled experiments to identify factors that influence measurements. For example, mouth rinse and oral pH reproducibly and significantly affect results and therefore must be controlled. Temperature and mode of breathing are other examples. As our understanding of these factors evolves, error is reduced, and clinical studies become more meaningful. This system is very reliable and individual measurements are inexpensive. The sampler is relatively inexpensive and quite portable, but the monitor is neither. This limits options for some clinical studies and provides rational for future innovations. PMID:24962141

Biodiesel transesterification kinetics monitored by pH measurement.

PubMed

Clark, William M; Medeiros, Nicholas J; Boyd, Donal J; Snell, Jared R

2013-05-01

Quantification of a pH change that was observed over the course of the transesterification reaction that converts vegetable oil to biodiesel may provide a simple method to monitor the reaction. Transesterification of canola oil at 6:1 methanol to oil ratio with 0.5 wt.% KOH as catalyst was studied at 25, 35, and 45 °C. Reaction conversion was correlated to pH measurements and the results were shown to be in agreement with an independent measure of conversion using an enzymatic assay for glycerol. Rate constants obtained from these measurements are consistent with those in the literature. The measured pH change appears to be related to dilution of OH(-) ions as the oil is converted to products rather than to depletion of OH(-) due to reaction. Copyright © 2013 Elsevier Ltd. All rights reserved.

Detecting Sulfuric and Nitric Acid Rain Stresses on Quercus glauca through Hyperspectral Responses

PubMed Central

Wang, Shanqian; Zhang, Xiuying; Ma, Yuandan; Li, Xinhui; Zhang, Xiaomin; Liu, Lei

2018-01-01

Acid rain, which has become one of the most severe global environmental issues, is detrimental to plant growth. However, effective methods for monitoring plant responses to acid rain stress are currently lacking. The hyperspectral technique provides a cost-effective and nondestructive way to diagnose acid rain stresses. Taking a widely distributed species (Quercus glauca) in Southern China as an example, this study aims to monitor the hyperspectral responses of Q. glauca to simulated sulfuric acid rain (SAR) and nitric acid rain (NAR). A total of 15 periods of leaf hyperspectral data under four pH levels of SAR and NAR were obtained during the experiment. The results showed that hyperspectral information could be used to distinguish plant responses under acid rain stress. An index (green peak area index, GPAI) was proposed to indicate acid rain stresses, based on the significantly variations in the region of 500–660 nm. Light acid rain (pH 4.5 SAR and NAR) promoted Q. glauca growth relative to the control groups (pH 5.6 SAR and NAR); moderate acid rain (pH 3.0 SAR) firstly promoted and then inhibited plant growth, while pH 3.0 NAR showed mild inhibitory effects during the experiment; and heavy acid rain (pH 2.0) significantly inhibited plant growth. Compared with NAR, SAR induced more serious damages to Q. glauca. These results could help monitor acid rain stress on plants on a regional scale using remote sensing techniques. PMID:29522488

Detecting Sulfuric and Nitric Acid Rain Stresses on Quercus glauca through Hyperspectral Responses.

PubMed

Wang, Shanqian; Zhang, Xiuying; Ma, Yuandan; Li, Xinhui; Cheng, Min; Zhang, Xiaomin; Liu, Lei

2018-03-09

Acid rain, which has become one of the most severe global environmental issues, is detrimental to plant growth. However, effective methods for monitoring plant responses to acid rain stress are currently lacking. The hyperspectral technique provides a cost-effective and nondestructive way to diagnose acid rain stresses. Taking a widely distributed species ( Quercus glauca ) in Southern China as an example, this study aims to monitor the hyperspectral responses of Q. glauca to simulated sulfuric acid rain (SAR) and nitric acid rain (NAR). A total of 15 periods of leaf hyperspectral data under four pH levels of SAR and NAR were obtained during the experiment. The results showed that hyperspectral information could be used to distinguish plant responses under acid rain stress. An index (green peak area index, GPAI) was proposed to indicate acid rain stresses, based on the significantly variations in the region of 500-660 nm. Light acid rain (pH 4.5 SAR and NAR) promoted Q. glauca growth relative to the control groups (pH 5.6 SAR and NAR); moderate acid rain (pH 3.0 SAR) firstly promoted and then inhibited plant growth, while pH 3.0 NAR showed mild inhibitory effects during the experiment; and heavy acid rain (pH 2.0) significantly inhibited plant growth. Compared with NAR, SAR induced more serious damages to Q. glauca . These results could help monitor acid rain stress on plants on a regional scale using remote sensing techniques.

[Ryan index for detection of laryngopharyngeal reflux diseases].

PubMed

Wu, W; Wang, G; Wang, L; Liu, H D; Wang, Q; Xu, X H; Ding, R Y; Xu, B X; Han, H L; Zhou, Y; Gong, J; Wang, H N; Li, B W; Sun, Z Z

2017-12-07

Objective: To explore the utility of pharyngeal pH monitoring which positive standard is Ryan index in diagnosis of laryngopharyngeal reflux disease. Methods: In a retrospective study, clinical data of 590 patients who had symptoms laryngopharyngeal reflux disease from February 2016 to March 2017 were analyzed. All patients were received electronic laryngoscopy, assessment of reflux symptom index(RSI) and reflux finding score(RFS), and pharyngeal pH monitoring. SPSS 19.0 software was used to analyze the date. Results: There were 94 patients whose Ryan index were positive(15.93%). Among the 94 patients, 70 were positive during upright, 12 during supine and 12 during both upright and supine. There were 40 patients(6.78%)with pH decline events related to symptoms, while those Ryan index were normal. There were 536(90.85%), 417(70.68%), 233(39.49%) and 117(19.83%) patients with pH<6.5, pH<6.0, pH<5.5 and pH<5.0 events respectively. The positive rate of RSI, RFS, RSI and RFS, RSI or RFS were 44.24%, 16.78%, 7.12%, 53.90% respectively. The RFS score in Ryan index positive group was higher than that in Ryan index negative group[(8.2±2.4) vs (4.0±2.9), u =5.424, P <0.05], while the RSI score in Ryan index positive group was not statistically different from that in Ryan index negative group[(11.3±6.2) vs (12.7±5.8), t =1.247, P =0.167]. Conclusions: Pharyngeal pH monitoring is an objective and non-invasive method which can reflect laryngopharyngeal reflux directly. However, with the Ryan index as a criterion for the diagnosis of laryngopharyngeal reflux disease, partial patients may be missed. Further studies are needed to obtain more accurate and objective laryngopharyngeal pH statistical index for diagnosis of laryngopharyngeal reflux disease.

The use of baseline measurements and geophysical models for the estimation of crustal deformations and the terrestrial reference system. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Bock, Y.

1982-01-01

Four possible estimators are investigated for the monitoring of crustal deformations from a combination of repeated baseline length measurements and adopted geophysical models, particularly an absolute motion plate model. The first estimator is an extension of the familiar free adjustment. The next two are Bayesian type estimators, one weak and one strong. Finally, a weighted constraint estimator is presented. The properties of these four estimators are outlined and their physical interpretations discussed. A series of simulations are performed to test the four estimators and to determine whether or not to incorporate a plate model for the monitoring of deformations. The application of these estimations to the maintenance of a new conventional terrestrial reference system is discussed.

Fully-Polymeric pH Sensor Realized by Means of a Single-Step Soft Embossing Technique

PubMed Central

Fanzio, Paola; Chang, Chi-Tung; Skolimowski, Maciej; Tanzi, Simone; Sasso, Luigi

2017-01-01

We present here an electrochemical sensor microsystem for the monitoring of pH. The all-polymeric device is comprised of a cyclic olefin copolymer substrate, a 200 nm-thin patterned layer of conductive polymer (PEDOT), and a 70 nm electropolymerized layer of a pH sensitive conductive polymer (polyaniline). The patterning of the fluidic (microfluidic channels) and conductive (wiring and electrodes) functional elements was achieved with a single soft PDMS mold via a single embossing step process. A post-processing treatment with ethylene glycol assured the functional enhancement of the electrodes, as demonstrated via an electrical and electrochemical characterization. A surface modification of the electrodes was carried out, based on voltammetric electropolymerization, to obtain a thin layer of polyaniline. The mechanism for pH sensing is based on the redox reactions of the polyaniline layer caused by protonation. The sensing performance of the microsystem was finally validated by monitoring its potentiometric response upon exposure to a relevant range of pH. PMID:28531106

A luminescent ratiometric pH sensor based on a nanoscale and biocompatible Eu/Tb-mixed MOF.

PubMed

Xia, Tifeng; Zhu, Fengliang; Jiang, Ke; Cui, Yuanjing; Yang, Yu; Qian, Guodong

2017-06-13

The precise and real-time monitoring of localized pH changes is of great importance in many engineering and environmental fields, especially for monitoring small pH changes in biological environments and living cells. Metal-organic frameworks (MOFs) with their nanoscale processability show very promising applications in bioimaging and biomonitoring, but the fabrication of nanoscale MOFs is still a challenge. In this study, we synthesized a nanoscale mixed-lanthanide metal-organic framework by a microemulsion method. The morphology and size of the NMOF can be simply adjusted by the addition of different amounts of the CTAB surfactant. This NMOF exhibits significant pH-dependent luminescence emission, which can act as a self-referenced pH sensor based on two emissions of Tb 3+ at 545 nm and Eu 3+ at 618 nm in the pH range from 3.00 to 7.00. The MTT assay and optical microscopy assay demonstrate the low cytotoxicity and good biocompatibility of the nanosensor.

Fully-Polymeric pH Sensor Realized by Means of a Single-Step Soft Embossing Technique.

PubMed

Fanzio, Paola; Chang, Chi-Tung; Skolimowski, Maciej; Tanzi, Simone; Sasso, Luigi

2017-05-20

We present here an electrochemical sensor microsystem for the monitoring of pH. The all-polymeric device is comprised of a cyclic olefin copolymer substrate, a 200 nm-thin patterned layer of conductive polymer (PEDOT), and a 70 nm electropolymerized layer of a pH sensitive conductive polymer (polyaniline). The patterning of the fluidic (microfluidic channels) and conductive (wiring and electrodes) functional elements was achieved with a single soft PDMS mold via a single embossing step process. A post-processing treatment with ethylene glycol assured the functional enhancement of the electrodes, as demonstrated via an electrical and electrochemical characterization. A surface modification of the electrodes was carried out, based on voltammetric electropolymerization, to obtain a thin layer of polyaniline. The mechanism for pH sensing is based on the redox reactions of the polyaniline layer caused by protonation. The sensing performance of the microsystem was finally validated by monitoring its potentiometric response upon exposure to a relevant range of pH.

The utility of ambulatory pH monitoring in patients presenting with chronic cough and asthma

PubMed Central

AlHabib, KF; Vedal, S; Champion, P; FitzGerald, JM

2007-01-01

OBJECTIVE: To evaluate the prevalence of gastroesophageal reflux disease (GERD) in patients presenting with asthma and chronic cough. PATIENTS AND METHODS: The charts of 358 consecutive patients who were referred for ambulatory gastroesophageal pH monitoring to the Lung Centre in Vancouver, British Columbia, were reviewed, and the data of 108 (30%) patients with asthma and 134 (37%) patients with chronic cough were analyzed. The maintenance treatment for GERD was discontinued before patients underwent the pH monitoring study. One hundred eighteen (33%) patients were excluded. RESULTS: Reflux episodes identified reflux events as the percentage of time where the pH was less than four. For asthma patients, 70 (64.8%) had distal total reflux, 50 (46.3%) had distal upright reflux, 41 (38.3%) had distal supine reflux and 73 (67.6%) had other distal refluxes. Proximal total reflux in asthmatic patients was present in 56 (52%), proximal upright reflux in 55 (51%) and proximal supine reflux in 56 (52%) patients. For chronic cough patients, 70 (52.6%) had distal total reflux, 59 (44.4%) had distal upright reflux, 45 (34.4%) had distal supine reflux and 75 (56%) patients had other distal refluxes. In chronic cough patients, proximal total reflux was present in 70 (52%), proximal upright reflux in 80 (60%) and proximal supine reflux in 59 (44%). Presenting respiratory and/or reflux symptoms were absent in approximately 25% of patients with asthma and reflux, and in approximately 50% of patients with chronic cough and reflux. During pH monitoring, symptoms did not differ significantly between those with and without distal reflux in both study groups, except for more significant heartburn in patients with chronic cough and reflux (RR 2.0). CONCLUSIONS: The data of the present study support the observation that there is a high prevalence of GERD in patients with asthma or chronic cough. The use of different pH parameters for detecting acid reflux during 24 h ambulatory pH monitoring, such as proximal esophageal acid measurement, should be considered as part of the routine interpretation of such testing. A low threshold for diagnosing GERD in patients with asthma or chronic cough is essential, because respiratory and/or reflux symptoms can be absent or atypical in some of these patients. PMID:17377644

COMBINED 24-HOURS ESOPHAGEAL PH MONITORING AND MULTICHANNEL INTRALUMINAL IMPEDANCE FOR COMPARISON OF GASTROESOPHAGEAL REFLUX IN CHILDREN WITH TYPICAL VERSUS ATYPICAL SYMPTOMS OF GASTROESOPHAGEAL REFLUX DISEASE.

PubMed

Dehghani, Seyed Mohsen; Taghavi, Seyed Alireza; Javaherizadeh, Hazhir; Nasri, Maryam

2016-01-01

- Gastroesophageal reflux disease is the most common esophageal disorder in pediatrics. - The aim of this study was to compare reflux parameters of typical and atypical symptoms of gastroesophageal reflux disease using 24-hour esophageal pH monitoring and multichannel intraluminal impedance in pediatric population. - In this prospective study, 43 patients aged less than 18 year with suspected gastroesophageal reflux disease were enrolled. The patients were divided into two groups based on the main presenting symptoms (typical versus atypical). Twenty four-hour pH monitoring and multichannel intraluminal impedance were performed in all the patients for comparing these two group regarding association of symptoms and reflux. Number of refluxes, pH related reflux, total reflux time, reflux more than 5 minutes, longest time of the reflux, lowest pH at reflux, reflux index were recorded and compared. Data comparison was done using SPSS. - The mean age of the patients was 5.7±3.4 years and 65.1% were male. Out of 43 patients 24 cases had typical symptoms and 19 had atypical symptoms. The mean reflux events detected by multichannel intraluminal impedance was more than mean reflux events detected by pH monitoring (308.4±115.8 vs 69.7±66.6) with P value of 0.037, which is statistically significant. The mean symptom index and symptom association probability were 35.01% ± 20.78% and 86.42% ± 25.79%, respectively in multichannel intraluminal impedance versus 12.73% ± 12.48% and 45.16% ± 42.29% in pH monitoring (P value <0.001). Number of acid reflux was 46.26±47.16 and 30.9±22.09 for atypical and typical symptoms respectively. The mean symptom index was 18.12% ± 13.101% and 8.30% ± 10.301% in atypical and typical symptoms respectively (P=0.034). Bolus clearance was longer in atypical symptoms compared typical symptoms(P<0.05). - Symptom index was significantly higher in atypical symptoms compared to typical symptoms. Higher number of acid reflux was found in children with atypical symptoms of reflux. Longer duration of bolus clearance was found in group with atypical symptoms of reflux.

Robotic platform for parallelized cultivation and monitoring of microbial growth parameters in microwell plates.

PubMed

Knepper, Andreas; Heiser, Michael; Glauche, Florian; Neubauer, Peter

2014-12-01

The enormous variation possibilities of bioprocesses challenge process development to fix a commercial process with respect to costs and time. Although some cultivation systems and some devices for unit operations combine the latest technology on miniaturization, parallelization, and sensing, the degree of automation in upstream and downstream bioprocess development is still limited to single steps. We aim to face this challenge by an interdisciplinary approach to significantly shorten development times and costs. As a first step, we scaled down analytical assays to the microliter scale and created automated procedures for starting the cultivation and monitoring the optical density (OD), pH, concentrations of glucose and acetate in the culture medium, and product formation in fed-batch cultures in the 96-well format. Then, the separate measurements of pH, OD, and concentrations of acetate and glucose were combined to one method. This method enables automated process monitoring at dedicated intervals (e.g., also during the night). By this approach, we managed to increase the information content of cultivations in 96-microwell plates, thus turning them into a suitable tool for high-throughput bioprocess development. Here, we present the flowcharts as well as cultivation data of our automation approach. © 2014 Society for Laboratory Automation and Screening.

Ratiometric Imaging of Extracellular pH in Dental Biofilms.

PubMed

Schlafer, Sebastian; Dige, Irene

2016-03-09

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. pH ratiometry exploits a pH-dependent shift in the fluorescent emission of pH-sensitive dyes. Calculation of the emission ratio at two different wavelengths allows determining local pH in microscopic images, irrespective of the concentration of the dye. Contrary to microelectrodes the technique 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) carboxylic acid (C-SNARF-4) is employed to monitor extracellular pH in in vivo grown dental biofilms of unknown species composition. Upon exposure to glucose the dye is up-concentrated inside all bacterial cells in the biofilms; it is thus used both as a universal bacterial stain and as a marker of extracellular pH. After confocal microscopic image acquisition, the bacterial biomass is removed from all pictures using digital image analysis software, which permits to exclusively calculate extracellular pH. pH ratiometry with the ratiometric dye is well-suited to study extracellular pH in thin biofilms of up to 75 µm thickness, but is limited to the pH range between 4.5 and 7.0.

Meet EPA Scientist Blake Schaeffer, Ph.D.

EPA Pesticide Factsheets

EPA research ecologist Blake Schaeffer, Ph.D. focuses on ways to use satellite remote sensing technology to monitor water quality. His research interests broadly include deriving water quality parameters in coasts, estuaries, and lakes using satellites

FRAM telescope - monitoring of atmospheric extinction and variable star photometry

NASA Astrophysics Data System (ADS)

Jurysek, J.; Honkova, K.; Masek, M.

2015-02-01

The FRAM (F/(Ph)otometric Robotic Atmospheric Monitor) telescope is a part of the Pierre Auger Observatory (PAO) located near town Malargüe in Argentina. The main task of the FRAM telescope is the continuous night - time monitoring of the atmospheric extinction and its wavelength dependence. The current methodology of the measurement of a atmospheric extinction and for instrumentation properties also allows simultaneous observation of other interesting astronomical targets. The current observations of the FRAM telescope are focused on the photometry of eclipsing binaries, positional refinement of minor bodies of the Solar system and observations of optical counterparts of gamma ray bursts. In this contribution, we briefly describe the main purpose of the FRAM telescope for the PAO and we also present its current astrono mical observing program.

MONITORING THE SPECIATION OF AQUEOUS FREE CHLORINE FROM PH 1-12 WITH RAMAN SPECTROSCOPY TO DETERMINE THE IDENTITY OF THE POTENT LOW-PH OXIDANT

EPA Science Inventory

The speciation of aqueous free chlorine above pH 5 is a well-understood equilibrium of H2O + HOCl (equilibrium) OCl- + H3O+ with a pKa of 7.5. However, the identity of another very potent oxidant present at low pH (below 5) has been attributed by some researchers to Cl2 (aq), a...

pH-based fiber optic biosensors for use in clinical and biotechnological applications

NASA Astrophysics Data System (ADS)

Mueller, Cord; Hitzmann, Bernd; Schubert, Florian; Scheper, Thomas

1995-05-01

The development of pH-based fiber optic biosensors and their uses in clinical and biotechnological applications are described. Based on a pH-sensitive optode, different biosensors for urea, penicillin, glucose and creatinine were developed. A multichannel modular fluorimeter was used to measure signals from up to three optodes simultaneously. The pH value and the buffer capacity are critical factors for biosensors based on pH probes and influence the biosensor signal. A flow injection analysis (FIA) system is used to eliminate the latter influences. With this integrated system, samples can be analyzed sequentially by the injection of a defined volume of each sample into a continuously flowing buffer stream that transports the samples to the sensors. The complex signal is transformed and analyzed by a computer system. Characteristic features of the FIA peak give information about the buffer capacity in the solution. With the help of intelligent computing (neural networks) it is possible to recognize these features and relate them to the respective buffer capacity to obtain more accurate values. Various applications of these biosensors are discussed. The pH optode is also used to monitor enzymatic reactions in non aqueous solvents. In this case the production of acetic acid can be detected on line.

Development of supported liquid membrane techniques for the monitoring of trace levels of organic pollutants in wastewaters and water purification systems

NASA Astrophysics Data System (ADS)

Msagati, Titus A. M.; Mamba, Bhekie B.

The supported liquid membrane (SLM) extraction technique has been developed and successfully used for the monitoring of trace quantities of ionisable organic contaminants, including 17β-estradiol and its metabolites, testosterones and their methyl ester derivatives, benzimidazole anthelmintic antibiotics and sulphonamides in aquatic systems. A number of parameters which control the mass transfer in the supported liquid membrane extraction process such as donor and acceptor pH, extraction time and the type of organic liquid membrane were optimised to enhance the efficiency of the liquid membrane in the removal of these compounds. The method developed gave very low detection limits (0.3 ng/l to 2.4 ng/l for 17β-estradiol and its metabolites; between 1 μg/l and 20 μg/l for sulphonamides; and between 0.1 ng/l and 10 ng/l for benzimidazole anthelmintic compounds). The SLM method showed good linearity, reproducibility and repeatability values and is therefore suitable for routine monitoring of such compounds in water and wastewater systems.

Gastroesophageal reflux evaluation in patients affected by chronic cough: Restech versus multichannel intraluminal impedance/pH metry.

PubMed

Ummarino, Dario; Vandermeulen, Liv; Roosens, Bart; Urbain, Daniel; Hauser, Bruno; Vandenplas, Yvan

2013-04-01

Oropharyngeal (OP) pH monitoring has been developed to detect supra-esophageal gastric reflux (SEGR). The results obtained with OP pH-metry and multichannel intraluminal impedance/pH monitoring (MII/pH) were compared. Diagnostic study. Ten patients (age 46.33 ± 9.86 years) presenting with chronic coughing underwent simultaneous OP and MII/pH recording. A 2-minute interval was allowed between events detected with both techniques to be considered simultaneous. A total of 515 reflux episodes were recorded with MII/pH (acid: 181; weakly acid: 310; weakly alkaline: 24); 180 (35%) reached the highest impedance channel (hypo-pharynx); 74/180 (41%) were not related to a change in pH, according to the antimony electrode of the MII/pH catheter located at the upper esophageal sphincter. The OP monitoring measured 39 acid events; 17 (43.6%) were swallows according to MII, and 15 (38.5%) were not associated with MII or pH change. Only seven episodes were detected simultaneously with both techniques (1.3% for MII vs. 18% for OP; P = 0.0002). We found 49 pH-only refluxes at the pH sensor in the hypo-pharynx with MII/pH; only three (6.1%) correlated with OP reflux. Correlation in time between cough and reflux events was positive in 5/10 patients for MII (symptom index 5/10, symptom association probability 4/10), but in 0/10 patients according to OP pH metry. OP pH metry detected less reflux episodes than MII/pH; 35% of the OP events were swallows according to impedance. Time correlation between cough and reflux could not be demonstrated with OP pH metry. Copyright © 2012 The American Laryngological, Rhinological, and Otological Society, Inc.

Noninvasive NIR measurement of tissue pH to assess hemorrhagic shock in swine

NASA Astrophysics Data System (ADS)

Soller, Babs R.; Zhang, Songbiao; Micheels, Ronald H.; Puyana, Juan C.

1999-07-01

Body-worn noninvasive physilogical sensors are needed to continuously monitor soldiers for hemorrhage and to provide real-time information for minimally skilled medics to treat the injured. In the hospital intramucosal pHi of the gut is used to monitor shock and its treatment. We hypothesize that abdominal wall muscle (AWM) pH can be measured noninvasively using near infrared (NIR) spectroscopy and partial least squares analysis (PLS) and will correlate with pHi. METHODS: AWM pH was measured with microelectrodes and gastric pHi was measured with a tonometric catheter simultaneously while NIR spectra were collected using prototype LED spectrometers placed on the pig's flanks. Animals were subject to hemorrhagic shock at 45 mm Hg for 45 minutes, then resuscitated with blood and lactated ringers. Relationships between electrode pH, pHi and NIR spectra were developed using PLS with cross validation. RESULTS: NIR spectral changes noninvasively acquired through the skin were shown to be from the muscle, not from changes in skin blood flow. Trending ability (R2) model accuracy (RMSD), and relative error were calculated for individual pigs. Using electrode pH as the reference, average R2 was 0.88 with a predicted accuracy of 0.17 pH units, a 9.3% relative error. Slightly degraded results were observed when pHi was used as a reference. CONCLUSIONS: NIR measurement of tissue pH can be used to noninvasively monitor for shock and guide its treatment in a swine model. These measurements correlate with gastric pHi, a clinically accepted measure of shock, providing an approach to develop similar methodology for humans.

Comparison of multichannel intraluminal impedance-pH monitoring and reflux scintigraphy in pediatric patients with suspected gastroesophageal reflux.

PubMed

Uslu Kızılkan, Nuray; Bozkurt, Murat Fani; Saltık Temizel, Inci Nur; Demir, Hülya; Yüce, Aysel; Caner, Biray; Özen, Hasan

2016-11-21

To evaluate the agreement of multichannel intraluminal impedance-pH monitoring (MII-pHM) and gastroesophageal reflux scintigraphy (GES) for the diagnosis of gastroesophageal reflux disease. Seventy-five consecutive patients with suspected gastroesophageal reflux disease (GERD) underwent 24-h combined MII-pHM recording and one hour radionuclide scintigraphy during the course of the MII-pHM study. Catheters with 6 impedance channels and 1 pH sensor were placed transnasally. Impedance and pH data analysis were performed automatically and manually. For impedance monitoring, reflux was defined as a retrograde 50% drop in impedance, starting distally and propagating retrogradely to at least the next two more proximal measuring channels. Reflux index (RI, percentage of the entire record that esophageal pH is < 4.0) greater than 4.2% for pHM and number of refluxes more than 50 for 24 h for MII were accepted as positive test results. At scintigraphy, 240 frames of 15 seconds duration were acquired in the supine position. Gastroesophageal reflux was defined as at least one reflux episode in the esophagus. After scintigraphic evaluation, impedance-pH recordings and scintigraphic images were evaluated together and agreement between tests were evaluated with Cohen's kappa. Sufficient data was obtained from 60 (80%) patients (34 male, 56.7%) with a mean age of 8.7 ± 3.7 years (range: 2.5-17.3 years; median: 8.5 years). Chronic cough, nausea, regurgitation and vomiting were the most frequent symptoms. The mean time for recording of MII-pHM was 22.8 ± 2.4 h (range: 16-30 h; median: 22.7 h). At least one test was positive in 57 (95%) patients. According to diagnostic criteria, GERD was diagnosed in 34 (57.7%), 44 (73.3%), 47 (78.3%) and 51 (85%) patients by means of pHM, MII, GES and MII-pHM, respectively. The observed percentage agreements/κ values for GES and pHM, GES and MII, GES and MII-pHM, and MII and pHM are 48.3%/-0.118; 61.7%/-0.042; 73.3%/0.116 and 60%/0.147, respectively. There was no or slight agreement between GES and pHM alone, MII alone or MII-pHM. pH monitoring alone missed 17 patients compared to combined MII-pHM. The addition of MII to pH monitoring increased the diagnosis rate by 50%. No or slight agreement was found among pH monitoring, MII monitoring, MII-pH monitoring and GES for the diagnosis of gastroesophageal reflux disease.

Comparison of multichannel intraluminal impedance-pH monitoring and reflux scintigraphy in pediatric patients with suspected gastroesophageal reflux

PubMed Central

Uslu Kızılkan, Nuray; Bozkurt, Murat Fani; Saltık Temizel, Inci Nur; Demir, Hülya; Yüce, Aysel; Caner, Biray; Özen, Hasan

2016-01-01

AIM To evaluate the agreement of multichannel intraluminal impedance-pH monitoring (MII-pHM) and gastroesophageal reflux scintigraphy (GES) for the diagnosis of gastroesophageal reflux disease. METHODS Seventy-five consecutive patients with suspected gastroesophageal reflux disease (GERD) underwent 24-h combined MII-pHM recording and one hour radionuclide scintigraphy during the course of the MII-pHM study. Catheters with 6 impedance channels and 1 pH sensor were placed transnasally. Impedance and pH data analysis were performed automatically and manually. For impedance monitoring, reflux was defined as a retrograde 50% drop in impedance, starting distally and propagating retrogradely to at least the next two more proximal measuring channels. Reflux index (RI, percentage of the entire record that esophageal pH is < 4.0) greater than 4.2% for pHM and number of refluxes more than 50 for 24 h for MII were accepted as positive test results. At scintigraphy, 240 frames of 15 seconds duration were acquired in the supine position. Gastroesophageal reflux was defined as at least one reflux episode in the esophagus. After scintigraphic evaluation, impedance-pH recordings and scintigraphic images were evaluated together and agreement between tests were evaluated with Cohen’s kappa. RESULTS Sufficient data was obtained from 60 (80%) patients (34 male, 56.7%) with a mean age of 8.7 ± 3.7 years (range: 2.5-17.3 years; median: 8.5 years). Chronic cough, nausea, regurgitation and vomiting were the most frequent symptoms. The mean time for recording of MII-pHM was 22.8 ± 2.4 h (range: 16-30 h; median: 22.7 h). At least one test was positive in 57 (95%) patients. According to diagnostic criteria, GERD was diagnosed in 34 (57.7%), 44 (73.3%), 47 (78.3%) and 51 (85%) patients by means of pHM, MII, GES and MII-pHM, respectively. The observed percentage agreements/κ values for GES and pHM, GES and MII, GES and MII-pHM, and MII and pHM are 48.3%/-0.118; 61.7%/-0.042; 73.3%/0.116 and 60%/0.147, respectively. There was no or slight agreement between GES and pHM alone, MII alone or MII-pHM. pH monitoring alone missed 17 patients compared to combined MII-pHM. The addition of MII to pH monitoring increased the diagnosis rate by 50%. CONCLUSION No or slight agreement was found among pH monitoring, MII monitoring, MII-pH monitoring and GES for the diagnosis of gastroesophageal reflux disease. PMID:27920480

Manipulating and Monitoring On-Surface Biological Reactions by Light-Triggered Local pH Alterations.

PubMed

Peretz-Soroka, Hagit; Pevzner, Alexander; Davidi, Guy; Naddaka, Vladimir; Kwiat, Moria; Huppert, Dan; Patolsky, Fernando

2015-07-08

Significant research efforts have been dedicated to the integration of biological species with electronic elements to yield smart bioelectronic devices. The integration of DNA, proteins, and whole living cells and tissues with electronic devices has been developed into numerous intriguing applications. In particular, the quantitative detection of biological species and monitoring of biological processes are both critical to numerous areas of medical and life sciences. Nevertheless, most current approaches merely focus on the "monitoring" of chemical processes taking place on the sensing surfaces, and little efforts have been invested in the conception of sensitive devices that can simultaneously "control" and "monitor" chemical and biological reactions by the application of on-surface reversible stimuli. Here, we demonstrate the light-controlled fine modulation of surface pH by the use of photoactive molecularly modified nanomaterials. Through the use of nanowire-based FET devices, we showed the capability of modulating the on-surface pH, by intensity-controlled light stimulus. This allowed us simultaneously and locally to control and monitor pH-sensitive biological reactions on the nanodevices surfaces, such as the local activation and inhibition of proteolytic enzymatic processes, as well as dissociation of antigen-antibody binding interactions. The demonstrated capability of locally modulating the on-surface effective pH, by a light stimuli, may be further applied in the local control of on-surface DNA hybridization/dehybridization processes, activation or inhibition of living cells processes, local switching of cellular function, local photoactivation of neuronal networks with single cell resolution and so forth.

Bioelectrochemical sulphate reduction on batch reactors: Effect of inoculum-type and applied potential on sulphate consumption and pH.

PubMed

Gacitúa, Manuel A; Muñoz, Enyelbert; González, Bernardo

2018-02-01

Microbial electrolysis batch reactor systems were studied employing different conditions, paying attention on the effect that biocathode potential has on pH and system performance, with the overall aim to distinguish sulphate reduction from H 2 evolution. Inocula from pure strains (Desulfovibrio paquesii and Desulfobacter halotolerans) were compared to a natural source conditioned inoculum. The natural inoculum possess the potential for sulphate reduction on serum bottles experiments due to the activity of mutualistic bacteria (Sedimentibacter sp. and Bacteroides sp.) that assist sulphate-reducing bacterial cells (Desulfovibrio sp.) present in the consortium. Electrochemical batch reactors were monitored at two different potentials (graphite-bar cathodes poised at -900 and -400mV versus standard hydrogen electrode) in an attempt to isolate bioelectrochemical sulphate reduction from hydrogen evolution. At -900mV all inocula were able to reduce sulphate with the consortium demonstrating superior performance (SO 4 2- consumption: 25.71gm -2 day -1 ), despite the high alkalinisation of the media. At -400mV only the pure Desulfobacter halotolerans inoculated system was able to reduce sulphate (SO 4 2- consumption: 17.47gm -2 day -1 ) and, in this potential condition, pH elevation was less for all systems, confirming direct (or at least preferential) bioelectrochemical reduction of sulphate over H 2 production. Copyright © 2017 Elsevier B.V. All rights reserved.

Computerized intrapartum electronic fetal monitoring: analysis of the decision to deliver for fetal distress.

PubMed

Georgieva, Antoniya; Payne, Stephen J; Moulden, Mary; Redman, Christopher W G

2011-01-01

We applied computerized methods to assess the Electronic Fetal Monitoring (EFM) in labor. We analyzed retrospectively the last hour of EFM for 1,370 babies, delivered by emergency Cesarean sections before the onset of pushing (data collected at the John Radcliffe Hospital, Oxford, UK). There were two cohorts according to the reason for intervention: (a) fetal distress, n(1) = 524 and (b) failure to progress and/or malpresentation, n(2) = 846. The cohorts were compared in terms of classical EFM features (baseline, decelerations, variability and accelerations), computed by a dedicated Oxford system for automated analysis--OxSys. In addition, OxSys was employed to simulate current clinical guidelines for the classification of fetal monitoring, i.e. providing in real time a three-tier grading system of the EFM (normal, indeterminate, or abnormal). The computerized features and the simulated guidelines corresponded well to the clinical management and to the actual labor outcome (measured by umbilical arterial pH).

Meet EPA Biologist Laura Jackson, Ph.D.

EPA Pesticide Factsheets

Research Biologist Laura Jackson, Ph.D., has worked for the EPA for 22 years, leading research initiatives in a diversity of disciplines, including environmental monitoring, land use planning, and the impacts that urbanization has on an area's ecology

Performance of ANFIS versus MLP-NN dissolved oxygen prediction models in water quality monitoring.

PubMed

Najah, A; El-Shafie, A; Karim, O A; El-Shafie, Amr H

2014-02-01

We discuss the accuracy and performance of the adaptive neuro-fuzzy inference system (ANFIS) in training and prediction of dissolved oxygen (DO) concentrations. The model was used to analyze historical data generated through continuous monitoring of water quality parameters at several stations on the Johor River to predict DO concentrations. Four water quality parameters were selected for ANFIS modeling, including temperature, pH, nitrate (NO3) concentration, and ammoniacal nitrogen concentration (NH3-NL). Sensitivity analysis was performed to evaluate the effects of the input parameters. The inputs with the greatest effect were those related to oxygen content (NO3) or oxygen demand (NH3-NL). Temperature was the parameter with the least effect, whereas pH provided the lowest contribution to the proposed model. To evaluate the performance of the model, three statistical indices were used: the coefficient of determination (R (2)), the mean absolute prediction error, and the correlation coefficient. The performance of the ANFIS model was compared with an artificial neural network model. The ANFIS model was capable of providing greater accuracy, particularly in the case of extreme events.

Layer-by-layer carbon nanotube bio-templates for in situ monitoring of the metabolic activity of nitrifying bacteria

NASA Astrophysics Data System (ADS)

Loh, Kenneth J.; Guest, Jeremy S.; Ho, Genevieve; Lynch, Jerome P.; Love, Nancy G.

2009-03-01

Despite the wide variety of effective disinfection and wastewater treatment techniques for removing organic and inorganic wastes, pollutants such as nitrogen remain in wastewater effluents. If left untreated, these nitrogenous wastes can adversely impact the environment by promoting the overgrowth of aquatic plants, depleting dissolved oxygen, and causing eutrophication. Although nitrification/denitrification processes are employed during advanced wastewater treatment, effective and efficient operation of these facilities require information of the pH, dissolved oxygen content, among many other parameters, of the wastewater effluent. In this preliminary study, a biocompatible CNT-based nanocomposite is proposed and validated for monitoring the biological metabolic activity of nitrifying bacteria in wastewater effluent environments (i.e., to monitor the nitrification process). Using carbon nanotubes and a pH-sensitive conductive polymer (i.e., poly(aniline) emeraldine base), a layer-by-layer fabrication technique is employed to fabricate a novel thin film pH sensor that changes its electrical properties in response to variations in ambient pH environments. Laboratory studies are conducted to evaluate the proposed nanocomposite's biocompatibility with wastewater effluent environments and its pH sensing performance.

Developing monitoring plans to detect spills related to natural gas production.

PubMed

Harris, Aubrey E; Hopkinson, Leslie; Soeder, Daniel J

2016-11-01

Surface water is at risk from Marcellus Shale operations because of chemical storage on drill pads during hydraulic fracturing operations, and the return of water high in total dissolved solids (up to 345 g/L) from shale gas production. This research evaluated how two commercial, off-the-shelf water quality sensors responded to simulated surface water pollution events associated with Marcellus Shale development. First, peak concentrations of contaminants from typical spill events in monitored watersheds were estimated using regression techniques. Laboratory measurements were then conducted to determine how standard in-stream instrumentation that monitor conductivity, pH, temperature, and dissolved oxygen responded to three potential spill materials: ethylene glycol (corrosion inhibitor), drilling mud, and produced water. Solutions ranging from 0 to 50 ppm of each spill material were assessed. Over this range, the specific conductivity increased on average by 19.9, 27.9, and 70 μS/cm for drilling mud, ethylene glycol, and produced water, respectively. On average, minor changes in pH (0.5-0.8) and dissolved oxygen (0.13-0.23 ppm) were observed. While continuous monitoring may be part of the strategy for detecting spills to surface water, these minor impacts to water quality highlight the difficulty in detecting spill events. When practical, sensors should be placed at the mouths of small watersheds where drilling activities or spill risks are present, as contaminant travel distance strongly affects concentrations in surface water systems.

Liquid-containing Refluxes and Acid Refluxes May Be Less Frequent in the Japanese Population Than in Other Populations: Normal Values of 24-hour Esophageal Impedance and pH Monitoring

PubMed Central

Kawamura, Osamu; Kohata, Yukie; Kawami, Noriyuki; Iida, Hiroshi; Kawada, Akiyo; Hosaka, Hiroko; Shimoyama, Yasuyuki; Kuribayashi, Shiko; Fujiwara, Yasuhiro; Iwakiri, Katsuhiko; Inamori, Masahiko; Kusano, Motoyasu; Hongo, Micho

2016-01-01

Background/Aims Twenty-four-hour esophageal impedance and pH monitoring allows detection of all types of reflux episodes and is considered the best technique for identifying gastroesophageal refluxes. However, normative data for the Japanese population are lacking. This multicenter study aimed to establish the normal range of 24-hour esophageal impedance and pH data both in the distal and the proximal esophagus in Japanese subjects. Methods Forty-two healthy volunteers (25 men and 17 women) with a mean ± standard deviation age of 33.3 ± 12.4 years (range: 22–72 years) underwent a combined 24-hour esophageal impedance and pH monitoring. According to the physical and pH properties, distal or proximal esophageal reflux events were categorized. Results Median 45 reflux events occurred in 24 hours, and the 95th percentile was 85 events. Unlike previous reports, liquid-containing reflux events are median 25/24 hours with the 95th percentile of 62/24 hours. Acidic reflux events were median 11/24 hours with the 95th percentile of 39/24 hours. Non-acidic gas reflux events were median 15/24 hours with the 95th percentile of 39/24 hours. Proximal reflux events accounted for 80% of the total reflux events and were mainly non-acidic gas refluxes. About 19% of liquid and mixed refluxes reached the proximal esophagus. Conclusions Unlike previous studies, liquid-containing and acidic reflux events may be less frequent in the Japanese population. Non-acidic gas reflux events may be frequent and a cause of frequent proximal reflux events. This study provides important normative data for 24-hour impedance and pH monitoring in both the distal and the proximal esophagus in the Japanese population. PMID:27247103

The corrosion mechanisms for primer coated 2219-T87 aluminum

NASA Technical Reports Server (NTRS)

Danford, Merlin D.; Knockemus, Ward W.

1987-01-01

To investigate metal surface corrosion and the breakdown of metal protective coatings, the ac Impedance Method was applied to zinc chromate primer coated 2219-T87 aluminum. The EG&GPARC Model 368 ac Impedance Measurement System, along with dc measurements with the same system using the Polarization Resistance Method, was used to monitor changing properties of coated aluminum disks immersed in 3.5 percent NaCl solutions buffered at pH 5.5 and pH 8.2 over periods of 40 days each. The corrosion system can be represented by an electronic analog called an equivalent circuit consisting of resistors and capacitors in specific arrangements. This equivalent circuit parallels the impedance behavior of the corrosion system during a frequency scan. Values for resistances and capacitances, that can be assigned in the equivalent circuit following a least squares analysis of the data, describe changes occurring on the corroding metal surface and in the protective coatings. A suitable equivalent circuit has been determined which predicts the correct Bode phase and magnitude for the experimental sample. The dc corrosion current density data are related to equivalent circuit element parameters.

Organelle-targeting surface-enhanced Raman scattering (SERS) nanosensors for subcellular pH sensing.

PubMed

Shen, Yanting; Liang, Lijia; Zhang, Shuqin; Huang, Dianshuai; Zhang, Jing; Xu, Shuping; Liang, Chongyang; Xu, Weiqing

2018-01-25

The pH value of subcellular organelles in living cells is a significant parameter in the physiological activities of cells. Its abnormal fluctuations are commonly believed to be associated with cancers and other diseases. Herein, a series of surface-enhanced Raman scattering (SERS) nanosensors with high sensitivity and targeting function was prepared for the quantification and monitoring of pH values in mitochondria, nucleus, and lysosome. The nanosensors were composed of gold nanorods (AuNRs) functionalized with a pH-responsive molecule (4-mercaptopyridine, MPy) and peptides that could specifically deliver the AuNRs to the targeting subcellular organelles. The localization of our prepared nanoprobes in specific organelles was confirmed by super-high resolution fluorescence imaging and bio-transmission electron microscopy (TEM) methods. By the targeting ability, the pH values of the specific organelles can be determined by monitoring the vibrational spectral changes of MPy with different pH values. Compared to the cases of reported lysosome and cytoplasm SERS pH sensors, more accurate pH values of mitochondria and nucleus, which could be two additional intracellular tracers for subcellular microenvironments, were disclosed by this SERS approach, further improving the accuracy of discrimination of related diseases. Our sensitive SERS strategy can also be employed to explore crucial physiological and biological processes that are related to subcellular pH fluctuations.

Ammonia Monitor

NASA Technical Reports Server (NTRS)

Sauer, Richard L. (Inventor); Akse, James R. (Inventor); Thompson, John O. (Inventor); Atwater, James E. (Inventor)

1999-01-01

Ammonia monitor and method of use are disclosed. A continuous, real-time determination of the concentration of ammonia in an aqueous process stream is possible over a wide dynamic range of concentrations. No reagents are required because pH is controlled by an in-line solid-phase base. Ammonia is selectively transported across a membrane from the process stream to an analytical stream to an analytical stream under pH control. The specific electrical conductance of the analytical stream is measured and used to determine the concentration of ammonia.

PhKv a toxin isolated from the spider venom induces antinociception by inhibition of cholinesterase activating cholinergic system.

PubMed

Rigo, Flavia Karine; Rossato, Mateus Fortes; Trevisan, Gabriela; De Prá, Samira Dal-Toé; Ineu, Rafael Porto; Duarte, Mariane Bernardo; de Castro Junior, Célio José; Ferreira, Juliano; Gomez, Marcus Vinicius

2017-10-01

Cholinergic agents cause antinociception by mimicking the release of acetylcholine (ACh) from spinal cholinergic nerves. PhKv is a peptide isolated from the venom of the armed spider Phoneutria nigriventer. It has an antiarrythmogenic activity that involves the enhanced release of acetylcholine. The aim of this study was to investigate whether PhKv had an antinociceptive action in mice. Male albino Swiss mice (25-35g) were used in this study. The PhKv toxin was purified from a PhTx3 fraction of the Phoneutria nigriventer spider's venom. Because of its peptide nature, PhKv is not orally available and it was delivered directly into the central nervous system by an intrathecal (i.t.) route. PhKV on the thermal and mechanical sensitivity was evaluated using plantar test apparatus and the up-and-down method. The analgesic effects of PhKv were studied in neuropathic pain (CCI) and in the peripheral capsicin test. In order to test whether PhKv interfered with the cholinergic system, the mice were pre-treated with atropine (5mg/kg, i.p.) or mecamylamine (0.001mg/kg, i.p.) and the PhKv toxin (30pmol/site i.t.) or neostigmine (100pmol/site) were applied 15min before the intraplantar capsaicin (1nmol/paw) administrations. To investigate PhKv action on the AChE activities, was performed in vitro and ex vivo assay for AChE. For the in vitro experiments, mice spinal cord supernatants of tissue homogenates (1mg/ml) were used as source of AChE activity. The AChE assay was monitored at 37°C for 10min in a FlexStation 3 Multi-Mode Microplate Reader (Molecular Devices) at 405nm. PhKv (30 and 100pmol/site, i.t.) had no effect on the thermal or mechanical sensitivity thresholds. However, in a chronic constriction injury model of pain, PhKv (10pmol/site, i.t.) caused a robust reduction in mechanical withdrawal with an antinociceptive effect that lasted 4h. A pretreatment in mice with PhKv (30pmol/site, i.t.) or neostigmine (100pmol/site, i.t.) 15min before an intraplantar injection of capsaicin (1nmol/paw) caused a maximal antinociceptive effect of 69.5±4.9% and 85±2.5%, respectively. A pretreatment in mice with atropine; 5mg/kg, i.p. or mecamylamine 0.001mg/kg, i.p. inhibited a neostigimine and PhKv-induced antinociception, suggesting a cholinergic mechanism. Spinal acetylcholinesterase was inhibited by PhKv with ED 50 of 7.6 (4.6-12.6pmol/site, i.t.). PhKv also inhibited the in vitro AChE activity of spinal cord homogenates with an EC 50 of 20.8 (11.6-37.3nM), shifting the Km value from 0.06mM to 18.5mM, characterizing a competitive inhibition of AChE activity by PhKv. Our findings provide, to our knowledge, the first evidence that PhKv caused inhibition of AChE, it increased the ACh content at the neuronal synapses, leading to an activation of the cholinergic system and an antinociceptive response. Studies regarding the nociceptive mechanisms and the identification of potential targets for the treatment of pain have become top priorities. PhKv, by its action of stimulating the cholinergic receptors muscarinic and nicotinic system, reduces pain it may be an alternative for controlling the pain processes. Copyright © 2017 Scandinavian Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

In Vivo Monitoring of pH, Redox Status, and Glutathione Using L-Band EPR for Assessment of Therapeutic Effectiveness in Solid Tumors

PubMed Central

Bobko, Andrey A.; Eubank, Timothy D.; Voorhees, Jeffrey L.; Efimova, Olga V.; Kirilyuk, Igor A.; Petryakov, Sergey; Trofimiov, Dmitrii G.; Marsh, Clay B.; Zweier, Jay L.; Grigor’ev, Igor A.; Samouilov, Alexandre; Khramtsov, Valery V.

2011-01-01

Approach for in vivo real-time assessment of tumor tissue extracellular pH (pHe), redox, and intracellular glutathione based on L-band EPR spectroscopy using dual function pH and redox nitroxide probe and disulfide nitroxide biradical, is described. These parameters were monitored in PyMT mice bearing breast cancer tumors during treatment with granulocyte macrophage colony-stimulating factor. It was observed that tumor pHe is about 0.4 pH units lower than that in normal mammary gland tissue. Treatment with granulocyte macrophage colony-stimulating factor decreased the value of pHe by 0.3 units compared with PBS control treatment. Tumor tissue reducing capacity and intracellular glutathione were elevated compared with normal mammary gland tissue. Granulocyte macrophage colony-stimulating factor treatment resulted in a decrease of the tumor tissue reducing capacity and intracellular glutathione content. In addition to spectroscopic studies, pHe mapping was performed using recently proposed variable frequency proton–electron double-resonance imaging. The pH mapping superimposed with MRI image supports probe localization in mammary gland/tumor tissue, shows high heterogeneity of tumor tissue pHe and a difference of about 0.4 pH units between average pHe values in tumor and normal mammary gland. In summary, the developed multifunctional approach allows for in vivo, noninvasive pHe, extracellular redox, and intracellular glutathione content monitoring during investigation of various therapeutic strategies for solid tumors. Magn Reson Med 000:000–000, 2011. PMID:22113626

Comparative Study of Poly (ε-Caprolactone) and Poly(Lactic-co-Glycolic Acid) -Based Nanofiber Scaffolds for pH-Sensing.

PubMed

Di, Wenjun; Czarny, Ryan S; Fletcher, Nathan A; Krebs, Melissa D; Clark, Heather A

2016-10-01

This study aims to develop biodegradable and biocompatible polymer-based nanofibers that continuously monitor pH within microenvironments of cultured cells in real-time. In the future, these fibers will provide a scaffold for tissue growth while simultaneously monitoring the extracellular environment. Sensors to monitor pH were created by directly electrospinning the sensor components within a polymeric matrix. Specifically, the entire fiber structure is composed of the optical equivalent of an electrode, a pH-sensitive fluorophore, an ionic additive, a plasticizer, and a polymer to impart mechanical stability. The resulting poly(ε-caprolactone) (PCL) and poly(lactic-co-glycolic acid) (PLGA) based sensors were characterized by morphology, dynamic range, reversibility and stability. Since PCL-based nanofibers delivered the most desirable analytical response, this matrix was used for cellular studies. Electrospun nanofiber scaffolds (NFSs) were created directly out of optode material. The resulting NFS sensors respond to pH changes with a dynamic range centered at 7.8 ± 0.1 and 9.6 ± 0.2, for PCL and PLGA respectively. NFSs exhibited multiple cycles of reversibility with a lifetime of at least 15 days with preservation of response characteristics. By comparing the two NFSs, we found PCL-NFSs are more suitable for pH sensing due to their dynamic range and superior reversibility. The proposed sensing platform successfully exhibits a response to pH and compatibility with cultured cells. NSFs will be a useful tool for creating 3D cellular scaffolds that can monitor the cellular environment with applications in fields such as drug discovery and tissue engineering.

Dual-Modal Colorimetric/Fluorescence Molecular Probe for Ratiometric Sensing of pH and Its Application.

PubMed

Wu, Luling; Li, Xiaolin; Huang, Chusen; Jia, Nengqin

2016-08-16

As traditional pH meters cannot work well for minute regions (such as subcellular organelles) and in harsh media, molecular pH-sensitive devices for monitoring pH changes in diverse local heterogeneous environments are urgently needed. Here, we report a new dual-modal colorimetric/fluorescence merocyanine-based molecular probe (CPH) for ratiometric sensing of pH. Compared with previously reported pH probes, CPH bearing the benzyl group at the nitrogen position of the indolium group and the phenol, which is used as the acceptor for proton, could respond to pH changes immediately through both the ratiometric fluorescence signal readout and naked-eye colorimetric observation. The sensing process was highly stable and reversible. Most importantly, the suitable pKa value (6.44) allows CPH to presumably accumulate in lysosomes and become a lysosome-target fluorescent probe. By using CPH, the intralysosomal pH fluctuation stimulated by antimalaria drug chloroquine was successfully tracked in live cells through the ratiometric fluorescence images. Additionally, CPH could be immobilized on test papers, which exhibited a rapid and reversible colorimetric response to acid/base vapor through the naked-eye colorimetric analysis. This proof-of-concept study presents the potential application of CPH as a molecular tool for monitoring intralysosomal pH fluctuation in live cells, as well as paves the way for developing the economic, reusable, and fast-response optical pH meters for colorimetric sensing acid/base vapor with direct naked-eye observation.

40 CFR 63.7741 - What are the installation, operation, and maintenance requirements for my monitors?

Code of Federal Regulations, 2013 CFR

2013-07-01

...; and (2) Install and maintain CPMS to measure and record the pH of the scrubber blowdown according to the requirements in paragraph (e)(2)(i) through (iv) of this section. (i) Locate the pH sensor in a position that provides a representative measurement of the pH and that minimizes or eliminates internal and...

Two 1,8- Naphthalimides as Proton-Receptor Fluorescent Sensors for Detecting PH

NASA Astrophysics Data System (ADS)

Wu, H.-L.; Peng, H.-P.; Wang, F.; Zhang, H.; Chen, C.-G.; Zhang, J.-W.; Yang, Z.-H.

2017-01-01

Two proton-receptor sensors for detecting pH change based on 1,8-naphthalimide, N-allyl-4-(4'-N,N-dioctylpropionamide-acetamido-piperazinyl)-1,8-naphthalimide ( 1), and N-(N,N-dioctylpropionamide-acetamido)-4-allyl-1-piperazinyl-1,8-naphthalimide ( 2), were designed, synthesized, and characterized. Photophysical characteristics of the sensors were investigated in different organic solvents and Britton-Robinson buffer/EtOH (1:1, v/v) solution. Sensor 2 displayed a good sensor activity towards protons within the pH range from 3.29 to 6.59, while sensor 1 demonstrated sensitivity to lower pH values from 2.21 to 4.35. The selectivity of the pH sensors toward protons in commonly used buffer solutions and in the presence of metal cations (Na+, K+, Ca2+, Mg2+, Al3+, Pb2+, Fe3+, Ni2+, Zn2+, Cu2+, Hg2+, Ag+, Co2+, Cr3+, Mn2+, and Cd2+) was studied by monitoring the changes in their fluorescence intensity. The results obtained indicate that the synthesized derivatives hold potential for monitoring pH variations between 2.21 and 6.59 in strong acid environments and bio-samples.

Intra-gastric pH following single oral administrations of rabeprazole and esomeprazole: double-blind cross-over comparison.

PubMed

Furuta, Kenji; Kohata, Yukie; Fujiwara, Yasuhiro; Sugimoto, Mitsushige; Uotani, Takahiro; Yamade, Mihoko; Sahara, Shu; Ichikawa, Hitomi; Furuta, Takahisa; Nio, Kenta; Iwakiri, Ryuichi; Inamori, Masahiko; Kawamura, Osamu; Kusano, Motoyasu; Kato, Mototsugu; Kawami, Noriyuki; Iwakiri, Katsuhiko; Takeuchi, Toshihisa; Higuchi, Kazuhide; Aimi, Masahito; Naora, Kohji; Fujimoto, Kazuma; Arakawa, Tetsuo; Kinoshita, Yoshikazu

2014-11-01

Comparisons between the acid inhibitory effects of rabeprazole and esomeprazole after single oral administration with standard doses have not been previously presented. We examined intra-gastric pH after oral administrations of these two proton pump inhibitors using 24-h pH monitoring. Fifty-four normal volunteers not infected by Helicobacter pylori were investigated. Using a cross-over design, we administered 10 mg of rabeprazole or 20 mg of esomeprazole in 27 at 30 min after supper and in the remaining 27 subjects at 15 min before supper, and performed 24-h pH monitoring. Intra-gastric pH data were nearly identical when the proton pump inhibitors were taken after meals. Even if the data were compared in different CYP2C19 genotypes, rabeprazole and esomeprazole did not show the difference. In poor metabolizer, both of the drugs showed stronger acid inhibition. When taken before meals, intra-gastric pH after esomeprazole administration was slightly but not significantly higher than that observed after rabeprazole administration not only in daytime but also in nighttime period. In conclusion, rabeprazole and esomeprazole were similarly effective when administered after a meal.

Double-pass Mach-Zehnder fiber interferometer pH sensor.

PubMed

Tou, Zhi Qiang; Chan, Chi Chiu; Hong, Jesmond; Png, Shermaine; Eddie, Khay Ming Tan; Tan, Terence Aik Huang

2014-04-01

A biocompatible fiber-optic pH sensor based on a unique double-pass Mach-Zehnder interferometer is proposed. pH responsive poly(2-hydroxyethyl methacrylate-co-2-(dimethylamino)ethyl methacrylate) hydrogel coating on the fiber swells/deswells in response to local pH, leading to refractive index changes that manifest as shifting of interference dips in the optical spectrum. The pH sensor is tested in spiked phosphate buffer saline and demonstrates high sensitivity of 1.71  nm/pH, pH 0.004 limit of detection with good responsiveness, repeatability, and stability. The proposed sensor has been successfully applied in monitoring the media pH in cell culture experiments to investigate the relationship between pH and cancer cell growth.

Equivalence of litmus paper and intragastric pH probes for intragastric pH monitoring in the intensive care unit.

PubMed

Levine, R L; Fromm, R E; Mojtahedzadeh, M; Baghaie, A A; Opekun, A R

1994-06-01

To compare the accuracy of litmus paper-determined gastric pH to a nasogastric graphite antimony pH probe. A prospective clinical trial of gastric pH determination in patients enrolled in a study of histamine-2-receptor (H2) antagonists. The medical intensive care unit (ICU) of a 450-bed county hospital. Critically ill ICU patients requiring stress ulcer prophylaxis. Using a crossover design, the patients were randomized to initially receive an H2 antagonist by continuous infusion or intravenous bolus, and subsequently were crossed over to the other limb of the study. Gastric pH was determined using pH-sensitive litmus paper at the initiation of each limb of the study and at 1, 2, 4, and 8 hrs after the initiation of H2 receptor antagonist therapy. In addition, gastric pH was continuously determined over the same time period utilizing a graphite antimony pH probe. Gastric pH measurements determined with litmus paper and intragastric pH probes demonstrated an excellent correlation (r2 = .93, p < .001). McNemar's test of correlated proportions could not demonstrate a significant difference between the two monitoring methods (chi-square = 0.5, p > .47), and the kappa statistic (0.95, p < .001) demonstrated excellent concordance. Bias measurement was 0.01 (95% confidence interval = -0.155 to 0.176). Measurement of intragastric pH, using pH-sensitive litmus paper, is both sensitive and specific when utilizing a graphite antimony nasogastric pH probe as a reference standard. Litmus paper-determined gastric pH testing is both easy to perform and inexpensive. Therefore, based on the current data, we believe this technique (i.e., litmus paper determined gastric pH testing) to be the method of choice for determination of intragastric pH in patients at risk for stress gastric ulcers in the medical ICU.

Optical measurement of acidification of human dental plaque in vitro

NASA Astrophysics Data System (ADS)

Graham, Jasmine Y.; Nelson, Leonard Y.; Seibel, Eric J.

2018-02-01

A pH measurement of oral biofilms is helpful for monitoring the impact of acidogenic bacteria in the caries process. Demineralization of dental enamel is closely related to the time dependent pH of human plaque. Therefore, providing a means to easily measure the local pH of biofilms is a useful clinical diagnostic in the arsenal of caries prevention tools. Optical measurement methods of plaque metabolism can use intrinsic fluorescence or extrinsic fluorescence from added dyes. Autofluorescence spectral features of human oral biofilms at green (500 nm) and red (634 nm) fluorescence wavelengths using 405 nm excitation did not demonstrate a spectral or intensity shift between neutral and acidic conditions. Chlorin e6, an ingredient in chlorophyllin food supplement, exhibited a spectral and intensity shift of fluorescence emission in buffered solutions, but this quantitative pH-dependence was not transferable to a human plaque environment. Finally, a ratiometric quantitative pH measure was achieved by exciting (405 nm laser) a mixture of two dyes, fluorescein and rhodamine B. This two-dye mixture produced two strong fluorescent bands centered at 515 nm (fluorescein) and 580 nm (rhodamine B), where the 515 nm band was pH sensitive and the 580 nm band served as a pH insensitive reference. This dual-dye fluorescence ratio exhibited a linear response over pH 7 to 5 in human oral biofilms during a sugar challenge. We have explored methods to use non-contact, optical measures of local acidity levels in difficult to access dental locations such as occlusal fissures using various pH sensitive fluorescent dye systems.

Development of a microbial time/temperature indicator prototype for monitoring the microbiological quality of chilled foods.

PubMed

Vaikousi, Hariklia; Biliaderis, Costas G; Koutsoumanis, Konstantinos P

2008-05-01

A time/temperature indicator (TTI) system based on the growth and metabolic activity of a Lactobacillus sakei strain was developed for monitoring food quality throughout the chilled-food chain. In the designed system, an irreversible color change of a chemical chromatic indicator (from red to yellow) progressively occurs due to the pH decline that results from microbial growth and metabolism in a selected medium. The relation of the TTI response (color change) to the growth and metabolic activity (glucose consumption, lactic acid production, pH decrease) of L. sakei was studied. In addition, the temperature dependence of the TTI kinetics was investigated isothermally in the range of 0 to 16 degrees C and modeled with a system of differential equations. At all temperatures tested, the pH and color changes of the TTI system followed closely the growth of L. sakei, with the endpoint (the time at which a distinct visual color change to the final yellow was observed) of the TTI coinciding with a population level of 10(7) to 10(8) CFU/ml. The endpoint decreased from 27 days at 0 degrees C to 2.5 days at 16 degrees C, yielding an activation energy of 97.7 kJ/mol, which was very close to the activation energy of the L. sakei growth rate in the TTI substrate (103.2 kJ/mol). Furthermore, experiments conducted on the effect of the inoculum level showed a negative linear relationship between the level of L. sakei inoculated in the system medium and the endpoint of the TTI. For example, the endpoint at 8 degrees C ranged from 6 to 2 days for inoculum levels of 10(1) and 10(6) CFU/ml, respectively. This relationship allows the easy adjustment of the TTI endpoint at a certain temperature according to the shelf life of the food product of concern by using an appropriate inoculum level of L. sakei. The microbial TTI prototype developed in the present study could be used as an effective tool for monitoring shelf life during the distribution and storage of food products that are spoiled primarily by lactic acid bacteria or other bacteria exhibiting similar kinetic responses and spoilage potentials. Apart from the low cost, the main advantage of the proposed TTI is that its response closely matches the loss of the quality of a food product by simulating the microbial spoilage process in particular environments.

Development of a Microbial Time/Temperature Indicator Prototype for Monitoring the Microbiological Quality of Chilled Foods▿

PubMed Central

Vaikousi, Hariklia; Biliaderis, Costas G.; Koutsoumanis, Konstantinos P.

2008-01-01

A time/temperature indicator (TTI) system based on the growth and metabolic activity of a Lactobacillus sakei strain was developed for monitoring food quality throughout the chilled-food chain. In the designed system, an irreversible color change of a chemical chromatic indicator (from red to yellow) progressively occurs due to the pH decline that results from microbial growth and metabolism in a selected medium. The relation of the TTI response (color change) to the growth and metabolic activity (glucose consumption, lactic acid production, pH decrease) of L. sakei was studied. In addition, the temperature dependence of the TTI kinetics was investigated isothermally in the range of 0 to 16°C and modeled with a system of differential equations. At all temperatures tested, the pH and color changes of the TTI system followed closely the growth of L. sakei, with the endpoint (the time at which a distinct visual color change to the final yellow was observed) of the TTI coinciding with a population level of 107 to 108 CFU/ml. The endpoint decreased from 27 days at 0°C to 2.5 days at 16°C, yielding an activation energy of 97.7 kJ/mol, which was very close to the activation energy of the L. sakei growth rate in the TTI substrate (103.2 kJ/mol). Furthermore, experiments conducted on the effect of the inoculum level showed a negative linear relationship between the level of L. sakei inoculated in the system medium and the endpoint of the TTI. For example, the endpoint at 8°C ranged from 6 to 2 days for inoculum levels of 101 and 106 CFU/ml, respectively. This relationship allows the easy adjustment of the TTI endpoint at a certain temperature according to the shelf life of the food product of concern by using an appropriate inoculum level of L. sakei. The microbial TTI prototype developed in the present study could be used as an effective tool for monitoring shelf life during the distribution and storage of food products that are spoiled primarily by lactic acid bacteria or other bacteria exhibiting similar kinetic responses and spoilage potentials. Apart from the low cost, the main advantage of the proposed TTI is that its response closely matches the loss of the quality of a food product by simulating the microbial spoilage process in particular environments. PMID:18326676

Combining Multi-Agent Systems and Wireless Sensor Networks for Monitoring Crop Irrigation.

PubMed

Villarrubia, Gabriel; Paz, Juan F De; Iglesia, Daniel H De La; Bajo, Javier

2017-08-02

Monitoring mechanisms that ensure efficient crop growth are essential on many farms, especially in certain areas of the planet where water is scarce. Most farmers must assume the high cost of the required equipment in order to be able to streamline natural resources on their farms. Considering that many farmers cannot afford to install this equipment, it is necessary to look for more effective solutions that would be cheaper to implement. The objective of this study is to build virtual organizations of agents that can communicate between each other while monitoring crops. A low cost sensor architecture allows farmers to monitor and optimize the growth of their crops by streamlining the amount of resources the crops need at every moment. Since the hardware has limited processing and communication capabilities, our approach uses the PANGEA architecture to overcome this limitation. Specifically, we will design a system that is capable of collecting heterogeneous information from its environment, using sensors for temperature, solar radiation, humidity, pH, moisture and wind. A major outcome of our approach is that our solution is able to merge heterogeneous data from sensors and produce a response adapted to the context. In order to validate the proposed system, we present a case study in which farmers are provided with a tool that allows us to monitor the condition of crops on a TV screen using a low cost device.

Combining Multi-Agent Systems and Wireless Sensor Networks for Monitoring Crop Irrigation

PubMed Central

Villarrubia, Gabriel; De Paz, Juan F.; De La Iglesia, Daniel H.; Bajo, Javier

2017-01-01

Monitoring mechanisms that ensure efficient crop growth are essential on many farms, especially in certain areas of the planet where water is scarce. Most farmers must assume the high cost of the required equipment in order to be able to streamline natural resources on their farms. Considering that many farmers cannot afford to install this equipment, it is necessary to look for more effective solutions that would be cheaper to implement. The objective of this study is to build virtual organizations of agents that can communicate between each other while monitoring crops. A low cost sensor architecture allows farmers to monitor and optimize the growth of their crops by streamlining the amount of resources the crops need at every moment. Since the hardware has limited processing and communication capabilities, our approach uses the PANGEA architecture to overcome this limitation. Specifically, we will design a system that is capable of collecting heterogeneous information from its environment, using sensors for temperature, solar radiation, humidity, pH, moisture and wind. A major outcome of our approach is that our solution is able to merge heterogeneous data from sensors and produce a response adapted to the context. In order to validate the proposed system, we present a case study in which farmers are provided with a tool that allows us to monitor the condition of crops on a TV screen using a low cost device. PMID:28767089

A Fiber Optic System For The Detection Of Entero-Gastric Reflux

NASA Astrophysics Data System (ADS)

Falciai, R.; Baldini, F.; Conforti, G.; Cosi, F.; Scheggi, A. M...; Bechi, P.

1989-01-01

The study and the development of an optical fiber sensor for entero-gastric and non-acid gastro-esophageal reflux is described. The working principle, based on the spectrophotometric properties of the bile, which constitutes the main part of the reflux, differs from the traditional measurement method, based on pH monitoring. The measuring apparatus is described as well as experimental "in vitro" and preliminary "in vivo" tests are reported.

Operation of remote mobile sensors for security of drinking water distribution systems.

PubMed

Perelman, By Lina; Ostfeld, Avi

2013-09-01

The deployment of fixed online water quality sensors in water distribution systems has been recognized as one of the key components of contamination warning systems for securing public health. This study proposes to explore how the inclusion of mobile sensors for inline monitoring of various water quality parameters (e.g., residual chlorine, pH) can enhance water distribution system security. Mobile sensors equipped with sampling, sensing, data acquisition, wireless transmission and power generation systems are being designed, fabricated, and tested, and prototypes are expected to be released in the very near future. This study initiates the development of a theoretical framework for modeling mobile sensor movement in water distribution systems and integrating the sensory data collected from stationary and non-stationary sensor nodes to increase system security. The methodology is applied and demonstrated on two benchmark networks. Performance of different sensor network designs are compared for fixed and combined fixed and mobile sensor networks. Results indicate that complementing online sensor networks with inline monitoring can increase detection likelihood and decrease mean time to detection. Copyright © 2013 Elsevier Ltd. All rights reserved.

Evaluating sensitivity of complex electrical methods for monitoring CO2 intrusion into a shallow groundwater system and associated geochemical transformations

NASA Astrophysics Data System (ADS)

Dafflon, B.; Wu, Y.; Hubbard, S. S.; Birkholzer, J. T.; Daley, T. M.; Pugh, J. D.; Peterson, J.; Trautz, R. C.

2011-12-01

A risk factor of CO2 storage in deep geological formations includes its potential to leak into shallow formations and impact groundwater geochemistry and quality. In particular, CO2 decreases groundwater pH, which can potentially mobilize naturally occurring trace metals and ions commonly absorbed to or contained in sediments. Here, geophysical studies (primarily complex electrical method) are being carried out at both laboratory and field scales to evaluate the sensitivity of geophysical methods for monitoring dissolved CO2 distribution and geochemical transformations that may impact water quality. Our research is performed in association with a field test that is exploring the effects of dissolved CO2 intrusion on groundwater geochemistry. Laboratory experiments using site sediments (silica sand and some fraction of clay minerals) and groundwater were initially conducted under field relevant CO2 partial pressures (pCO2). A significant pH drop was observed with inline sensors with concurrent changes in fluid conductivity caused by CO2 dissolution. Electrical resistivity and electrical phase responses correlated well with the CO2 dissolution process at various pCO2. Specifically, resistivity decreased initially at low pCO2 condition resulting from CO2 dissolution followed by a slight rebound because of the transition of bicarbonate into non-dissociated carbonic acid at lower pH slightly reducing the total concentration of dissociated species. Continuous electrical phase decreases were also observed, which are interpreted to be driven by the decrease of surface charge density (due to the decrease of pH, which approaches the PZC of the sediments). In general, laboratory experiments revealed the sensitivity of electrical signals to CO2 intrusion into groundwater formations and can be used to guide field data interpretation. Cross well complex electrical data are currently being collected periodically throughout a field experiment involving the controlled release of dissolved CO2 into groundwater. The objective of the geophysical cross well monitoring effort is to evaluate the sensitivity of complex electrical methods to dissolved CO2 at the field scale. Here, we report on the ability to translate laboratory-based petrophysical information from lab to field scales, and on the potential of field complex electrical methods for remotely monitoring CO2-induced geochemical transformations.

Bacterially produced Pt-GFP as ratiometric dual-excitation sensor for in planta mapping of leaf apoplastic pH in intact Avena sativa and Vicia faba.

PubMed

Geilfus, Christoph-Martin; Mühling, Karl H; Kaiser, Hartmut; Plieth, Christoph

2014-01-01

Ratiometric analysis with H(+)-sensitive fluorescent sensors is a suitable approach for monitoring apoplastic pH dynamics. For the acidic range, the acidotropic dual-excitation dye Oregon Green 488 is an excellent pH sensor. Long lasting (hours) recordings of apoplastic pH in the near neutral range, however, are more problematic because suitable pH indicators that combine a good pH responsiveness at a near neutral pH with a high photostability are lacking. The fluorescent pH reporter protein from Ptilosarcus gurneyi (Pt-GFP) comprises both properties. But, as a genetically encoded indicator and expressed by the plant itself, it can be used almost exclusively in readily transformed plants. In this study we present a novel approach and use purified recombinant indicators for measuring ion concentrations in the apoplast of crop plants such as Vicia faba L. and Avena sativa L. Pt-GFP was purified using a bacterial expression system and subsequently loaded through stomata into the leaf apoplast of intact plants. Imaging verified the apoplastic localization of Pt-GFP and excluded its presence in the symplast. The pH-dependent emission signal stood out clearly from the background. PtGFP is highly photostable, allowing ratiometric measurements over hours. By using this approach, a chloride-induced alkalinizations of the apoplast was demonstrated for the first in oat. Pt-GFP appears to be an excellent sensor for the quantification of leaf apoplastic pH in the neutral range. The presented approach encourages to also use other genetically encoded biosensors for spatiotemporal mapping of apoplastic ion dynamics.

Comparing the acidities of aqueous, frozen, and freeze-dried phosphate buffers: Is there a "pH memory" effect?

PubMed

Vetráková, Ľubica; Vykoukal, Vít; Heger, Dominik

2017-09-15

The concept of "pH memory" has been established in the literature for the correlation between the pH of a pre-lyophilization solution and the ionization state of freeze-dried powder (lyophile). In this paper, the concept of "pH memory" is explored for the system of an aqueous solution, a frozen solution, and a lyophile. Sodium and potassium phosphate buffers in the pH range of 5-9 were frozen and lyophilized with sulfonephthalein indicators as acidity probes, and their Hammett acidity functions were compared to the initial pH of the aqueous solution. The results show that the acidities of the lyophiles are somewhat changed compared to the initial pHs, but the acidities in the frozen state differ more substantially. The Hammett acidity functions of the frozen buffers were found to be markedly dissimilar from the initial pH, especially in the sodium phosphate frozen at 233K, where an increase in the initial pH led to a decrease in the Hammett acidity function of the frozen state at a certain pH range. The large acidification observed after freezing the sodium phosphate buffer was not detected in the lyophiles after the sample had been dried; the phenomenon is explained considering the formed crystals analyzed by X-ray powder diffraction. The results suggest that monitoring the final acidity of a lyophile is not sufficient to predict all the acidity changes throughout the whole lyophilization process. The importance of well-controlled freezing and lyophilization conditions follows from the results of the research. Copyright © 2017 Elsevier B.V. All rights reserved.

Changes in wintertime pH and hydrography of the Gulf of Finland (Baltic Sea) with focus on depth layers.

PubMed

Almén, Anna-Karin; Glippa, Olivier; Pettersson, Heidi; Alenius, Pekka; Engström-Öst, Jonna

2017-04-01

We studied changes in sea water pH, temperature and salinity with focus on two depth layers, along the Gulf of Finland (the Baltic Sea) using long-term monitoring data from 1979 to 2015. Data from the most frequently sampled monitoring stations between western and eastern Gulf of Finland were used. The main result of the study reveals that pH has decreased both in surface and deep-water in the western Gulf of Finland with values ranging between -0.005 and -0.008 units year -1 . We also demonstrate a rise in temperature (~2 °C) and decrease in salinity (~-0.7 g kg -1 ) at several stations over the last 36 years. In general, the changes are shown to be more pronounced in the western part of the gulf. This paper also stresses the importance of improving the sampling frequency and quality of monitoring measurements.

Sonoelasticity to monitor mechanical changes during rigor and ageing.

PubMed

Ayadi, A; Culioli, J; Abouelkaram, S

2007-06-01

We propose the use of sonoelasticity as a non-destructive method to monitor changes in the resistance of muscle fibres, unaffected by connective tissue. Vibrations were applied at low frequency to induce oscillations in soft tissues and an ultrasound transducer was used to detect the motions. The experiments were carried out on the M. biceps femoris muscles of three beef cattle. In addition to the sonoelasticity measurements, the changes in meat during rigor and ageing were followed by measurements of both the mechanical resistance of myofibres and pH. The variations of mechanical resistance and pH were compared to those of the sonoelastic variables (velocity and attenuation) at two frequencies. The relationships between pH and velocity or attenuation and between the velocity or attenuation and the stress at 20% deformation were highly correlated. We concluded that sonoelasticity is a non-destructive method that can be used to monitor mechanical changes in muscle fibers during rigor-mortis and ageing.

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

NASA Astrophysics Data System (ADS)

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.

Development of an Integrated ISFET pH Sensor for High Pressure Applications in the Deep-Sea

DTIC Science & Technology

2012-09-30

Measurements in the upper ocean suggest that sensor precision is comparable to the annual pH change due to ocean acidification (Fig. 2). An array of...profiling floats equipped with pH sensors would be capable of directly monitoring the process of ocean acidification . Further refinement of the sensor...Quality of Life The high pressure pH sensor will have direct applications to our understanding of ocean acidification and the impacts on ecosystem

Studying the influence of stem composition in pH-sensitive molecular beacons onto their sensing properties.

PubMed

Dembska, Anna; Kierzek, Elzbieta; Juskowiak, Bernard

2017-10-16

Intracellular sensing using fluorescent molecular beacons is a potentially useful strategy for real-time, in vivo monitoring of important cellular events. This work is focused on evaluation of pyrene excimer signaling molecular beacons (MBs) for the monitoring of pH changes in vitro as well as inside living cells. The recognition element in our MB called pHSO (pH-sensitive oligonucleotide) is the loop enclosing cytosine-rich fragment that is able to form i-motif structure in a specific pH range. However, alteration of a sequence of the 6 base pairs containing stem of MB allowed the design of pHSO probes that exhibited different dynamic pH range and possessed slightly different transition midpoint between i-motif and open loop configuration. Moreover, this conformational transition was accompanied by spectral changes showing developed probes different pyrene excimer-monomer emission ratio triggered by pH changes. The potential of these MBs for intracellular pH sensing is demonstrated on the example of HeLa cells line. Copyright © 2017 Elsevier B.V. All rights reserved.

Monitoring protein hydrolysis by pepsin using pH-stat: In vitro gastric digestions in static and dynamic pH conditions.

PubMed

Mat, Damien J L; Cattenoz, Thomas; Souchon, Isabelle; Michon, Camille; Le Feunteun, Steven

2018-01-15

This study intends to demonstrate that acid titration at low pH is very well adapted to the monitoring of pepsin activity. After a description of the underlying principles, this approach was used during in vitro gastric digestions of a model of complex food containing 15wt% of whey proteins, according to both static (2h at pH = 3, Infogest protocol) and dynamic pH conditions (from pH 6.3 down to 2 in 1h). Pepsin activity was quantitatively assessed in all experiments through the calculation of degrees of hydrolysis (DH). Final values of 3.7 and 3.0% were obtained in static and dynamic pH conditions, respectively, and validated using an independent method. Results also show that about 92% of the peptides were detected at pH = 3, and 100% for pH≤2.5. Overall, the proposed approach proved to be very worthy to study protein hydrolysis during in vitro gastric digestions. Copyright © 2017 Elsevier Ltd. All rights reserved.

In situ chemical sensing for hydrothermal plume mapping and modeling

NASA Astrophysics Data System (ADS)

Fukuba, T.; Kusunoki, T.; Maeda, Y.; Shitashima, K.; Kyo, M.; Fujii, T.; Noguchi, T.; Sunamura, M.

2012-12-01

Detection, monitoring, and mapping of biogeochemical anomalies in seawater such as temperature, salinity, turbidity, oxidation-reduction potential, and pH are essential missions to explore undiscovered hydrothermal sites and to understand distribution and behavior of hydrothermal plumes. Utilization of reliable and useful in situ sensors has been widely accepted as a promised approach to realize a spatiotemporally resolved mapping of anomalies without water sampling operations. Due to remarkable progresses of sensor technologies and its relatives, a number of highly miniaturized and robust chemical sensors have been proposed and developed. We have been developed, evaluated, and operated a compact ISFET (Ion-Sensitive Field-Effect Transistor)-based chemical sensors for ocean environmental sensing purposes. An ISFET has advantages against conventional glass-based electrodes on its faster response, robustness, and potential on miniaturization, and thus variety of chemical sensors has been already on the market. In this study, ISFET-based standalone pH sensors with a solid-state Cl-ISE as a reference electrode were mounted on various platforms and operated to monitor the pH anomalies in deep-sea environment at the Kairei, Edmond, and surrounding hydrothermal sites in the southern Central Indian Ridge area during KH10-06 scientific cruise (Nov. 2010), supported by project TAIGA (Trans-crustal Advection and In situ biogeochemical processes of Global sub-seafloor Aquifer). Up to three pH sensors were mounted on a wire-lined CTD/RMS (Rosette Multiple Sampler), dredge sampler, a series of MTD plankton nets, and VMPS (Vertical Multiple-operating Plankton Sampler). A standalone temperature sensor was bundled and operated with the pH sensor when they were mounted on the dredge sampler, MTD plankton nets, and VMPS. An AUV equipped with the pH sensor was also operated for hydrothermal activity survey operations. As a result of Tow-Yo intersect operations of the CTD/RMS, distribution of pH anomalies were successfully visualized at the Kairei site. During the operations with the dredge sampler, MTD nets, and VMPS, the pH sensors successfully worked except for a few failures of measurements due to a problem on a sensor cable. The pH sensor mounted on the AUV "R2D4" recoded a weak low-pH anomaly during a dive at the Yokoniwa site. Representative of the pH data obtained at southern Central Indian Ride will be shown visually on the poster. The spatiotemporally resolved data can be also utilized to develop reliable numerical models to estimate fluxes of energy and matters from geologically active sites. An example of optimization of a numerical model for hydrothermal plume study using 4D pH data obtained at a back-arc hydrothermal system (the Hatoma-knoll, the Okinawa Trough, Japan) will be also presented.

NeuronRead, an open source semi-automated tool for morphometric analysis of phase contrast and fluorescence neuronal images.

PubMed

Dias, Roberto A; Gonçalves, Bruno P; da Rocha, Joana F; da Cruz E Silva, Odete A B; da Silva, Augusto M F; Vieira, Sandra I

2017-12-01

Neurons are specialized cells of the Central Nervous System whose function is intricately related to the neuritic network they develop to transmit information. Morphological evaluation of this network and other neuronal structures is required to establish relationships between neuronal morphology and function, and may allow monitoring physiological and pathophysiologic alterations. Fluorescence-based microphotographs are the most widely used in cellular bioimaging, but phase contrast (PhC) microphotographs are easier to obtain, more affordable, and do not require invasive, complicated and disruptive techniques. Despite the various freeware tools available for fluorescence-based images analysis, few exist that can tackle the more elusive and harder-to-analyze PhC images. To surpass this, an interactive semi-automated image processing workflow was developed to easily extract relevant information (e.g. total neuritic length, average cell body area) from both PhC and fluorescence neuronal images. This workflow, named 'NeuronRead', was developed in the form of an ImageJ macro. Its robustness and adaptability were tested and validated on rat cortical primary neurons under control and differentiation inhibitory conditions. Validation included a comparison to manual determinations and to a golden standard freeware tool for fluorescence image analysis. NeuronRead was subsequently applied to PhC images of neurons at distinct differentiation days and exposed or not to DAPT, a pharmacological inhibitor of the γ-secretase enzyme, which cleaves the well-known Alzheimer's amyloid precursor protein (APP) and the Notch receptor. Data obtained confirms a neuritogenic regulatory role for γ-secretase products and validates NeuronRead as a time- and cost-effective useful monitoring tool. Copyright © 2017. Published by Elsevier Inc.

Controlled ecological life support systems: Development of a plant growth module

NASA Technical Reports Server (NTRS)

Averner, Mel M.; Macelroy, Robert D.; Smernoff, David T.

1987-01-01

An effort was made to begin defining the scientific and technical requirements for the design and construction of a ground-based plant growth facility. In particular, science design criteria for the Plant Growth Module (PGM) of the Controlled Ecological Life Support System (CELSS) were determined in the following areas: (1) irradiation parameters and associated equipment affecting plant growth; (2) air flow; (3) planting, culture, and harvest techniques; (4) carbon dioxide; (5) temperature and relative humidity; (6) oxygen; (7) construction materials and access; (8) volatile compounds; (9) bacteria, sterilization, and filtration; (10) nutrient application systems; (11) nutrient monitoring; and (12) nutrient pH and conductivity.

Combining inkjet printing and sol-gel chemistry for making pH-sensitive surfaces.

PubMed

Orsi, Gianni; De Maria, Carmelo; Montemurro, Francesca; Chauhan, Veeren M; Aylott, Jonathan W; Vozzi, Giovanni

2015-01-01

Today biomedical sciences are experiencing the importance of imaging biological parameters with luminescence methods. Studying 2D pH distribution with those methods allows building knowledge about complex cellular processes. Immobilizing pH sensitive nanoparticles inside hydrogel matrixes, in order to guarantee a proper SNR, could easily make stable and biocompatible 2D sensors. Inkjet printing is also well known as tool for printing images onto porous surfaces. Recently it has been used as a free-form fabrication method for building three-dimensional parts, and now is being explored as a way of printing electrical and optical devices. Inkjet printing was used either as a rapid prototyping method for custom biosensors. Sol-gel method is naturally bound with inkjet, because the picoliter-sized ink droplets evaporate quickly, thus allowing quick sol-gel transitions on the printed surface. In this work will be shown how to merge those technologies, in order to make a nanoparticles doped printable hydrogel, which could be used for making 2D/3D smart scaffolds able to monitor cell activities. An automated image analysis system was developed in order to quickly have the pH measurements from pH nanosensors fluorescence images.

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

PubMed

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. 

ORGANOPHOSPHORUS HYDROLASE-BASED ASSAY FOR ORGANOPHOSPHATE PESTICIDES

EPA Science Inventory

We report a rapid and versatile Organophosphorus hydrolase (OPH)-based method for measurement of organophosphates. This assay is based on a substrate-dependent change in pH at the local vicinity of the enzyme. The pH change is monitored using fluorescein isothiocyanate (FITC), ...

In Vivo Proton–Electron Double-Resonance Imaging of Extracellular Tumor pH Using an Advanced Nitroxide Probe

PubMed Central

Samouilov, Alexandre; Efimova, Olga V.; Bobko, Andrey A.; Sun, Ziqi; Petryakov, Sergey; Eubank, Timothy D.; Trofimov, Dmitrii G.; Kirilyuk, Igor A.; Grigor’ev, Igor A.; Takahashi, Wataru; Zweier, Jay L.; Khramtsov, Valery V.

2014-01-01

A variable radio frequency proton–electron double-resonance imaging (VRF PEDRI) approach for pH mapping of aqueous samples has been recently developed (Efimova et al. J. Magn. Reson. 2011, 209, 227–232). A pH map is extracted from two PEDRI acquisitions performed at electron paramagnetic resonance (EPR) frequencies of protonated and unprotonated forms of a pH-sensitive probe. To translate VRF PEDRI to an in vivo setting, an advanced pH probe was synthesized. Probe deuteration resulted in a narrow spectral line of 1.2 G compared to a nondeuterated analogue line width of 2.1 G allowing for an increase of Overhauser enhancements and reduction in rf power deposition. Binding of the probe to the cell-impermeable tripeptide, glutathione (GSH), allows for targeting to extracellular tissue space for monitoring extracellular tumor acidosis, a prognostic factor in tumor pathophysiology. The probe demonstrated pH sensitivity in the 5.8–7.8 range, optimum for measurement of acidic extracellular tumor pH (pHe). In vivo VRF PEDRI was performed on Met-1 tumor-bearing mice. Compared to normal mammary glands with a neutral mean pHe (7.1 ± 0.1), we observed broader pH distribution with acidic mean pHe (6.8 ± 0.1) in tumor tissue. In summary, VRF PEDRI in combination with a newly developed pH probe provides an analytical approach for spatially resolved noninvasive pHe monitoring, in vivo. PMID:24372284

Optical pen-size reflectometer for monitoring of early dental erosion in native and polished enamels.

PubMed

Rakhmatullina, Ekaterina; Bossen, Anke; Bachofner, Kai K; Meier, Christoph; Lussi, Adrian

2013-11-01

Application of the specular reflection intensity was previously reported for the quantification of early dental erosion. Further development of the technique and assembly of the miniaturized pen-size instrument are described. The optical system was adjusted to fit into a handy device which could potentially access different positions in the oral cavity. The assembled instrument could successfully detect early erosion progression in both polished (n=70) and native (n=20) human enamels. Different severities of enamel erosion were induced by varying incubation time of polished enamel in 1% citric acid (pH=3.60, 0.5 to 10 min), while the native incisors were treated in the commercial orange juice (Tropicana Pure Premium®, pH=3.85, 10 to 60 min). The instrument provided a good differentiation between various severities of the erosion in vitro. The size of the measurement spot affected the erosion monitoring in native enamel (human incisors). The erosion measurement in the 0.7-mm (diameter) cervical spots showed systematically lower reflection intensities compared with the analysis of central and incisal small spots. The application of larger spot areas (2.3 mm) for the erosion monitoring revealed no effect (p>0.05) of the spot position on the reflection signal. High variation of the teeth susceptibility toward in vitro erosion was detected in native enamel.

Aluminum Gallium Nitride (GaN)/GaN High Electron Mobility Transistor-Based Sensors for Glucose Detection in Exhaled Breath Condensate

PubMed Central

Chu, Byung Hwan; Kang, Byoung Sam; Hung, Sheng Chun; Chen, Ke Hung; Ren, Fan; Sciullo, Andrew; Gila, Brent P.; Pearton, Stephen J.

2010-01-01

Background Immobilized aluminum gallium nitride (AlGaN)/GaN high electron mobility transistors (HEMTs) have shown great potential in the areas of pH, chloride ion, and glucose detection in exhaled breath condensate (EBC). HEMT sensors can be integrated into a wireless data transmission system that allows for remote monitoring. This technology offers the possibility of using AlGaN/GaN HEMTs for extended investigations of airway pathology of detecting glucose in EBC without the need for clinical visits. Methods HEMT structures, consisting of a 3-μm-thick undoped GaN buffer, 30-Å-thick Al0.3Ga0.7N spacer, and 220-Å-thick silicon-doped Al0.3Ga0.7N cap layer, were used for fabricating the HEMT sensors. The gate area of the pH, chloride ion, and glucose detection was immobilized with scandium oxide (Sc2O3), silver chloride (AgCl) thin film, and zinc oxide (ZnO) nanorods, respectively. Results The Sc2O3-gated sensor could detect the pH of solutions ranging from 3 to 10 with a resolution of ∼0.1 pH. A chloride ion detection limit of 10-8 M was achievedt with a HEMT sensor immobilized with the AgCl thin film. The drain–source current of the ZnO nanorod-gated AlGaN/GaN HEMT sensor immobilized with glucose oxidase showed a rapid response of less than 5 seconds when the sensor was exposed to the target glucose in a buffer with a pH value of 7.4. The sensor could detect a wide range of concentrations from 0.5 nM to 125 μM. Conclusion There is great promise for using HEMT-based sensors to enhance the detection sensitivity for glucose detection in EBC. Depending on the immobilized material, HEMT-based sensors can be used for sensingt different materials. These electronic detection approaches with rapid response and good repeatability show potential for the investigation of airway pathology. The devices can also be integrated into a wireless data transmission system for remote monitoring applications. This sensor technology could use the exhaled breath condensate to measure the glucose concentration for diabetic applications. PMID:20167182

Aluminum gallium nitride (GaN)/GaN high electron mobility transistor-based sensors for glucose detection in exhaled breath condensate.

PubMed

Chu, Byung Hwan; Kang, Byoung Sam; Hung, Sheng Chun; Chen, Ke Hung; Ren, Fan; Sciullo, Andrew; Gila, Brent P; Pearton, Stephen J

2010-01-01

Immobilized aluminum gallium nitride (AlGaN)/GaN high electron mobility transistors (HEMTs) have shown great potential in the areas of pH, chloride ion, and glucose detection in exhaled breath condensate (EBC). HEMT sensors can be integrated into a wireless data transmission system that allows for remote monitoring. This technology offers the possibility of using AlGaN/GaN HEMTs for extended investigations of airway pathology of detecting glucose in EBC without the need for clinical visits. HEMT structures, consisting of a 3-microm-thick undoped GaN buffer, 30-A-thick Al(0.3)Ga(0.7)N spacer, and 220-A-thick silicon-doped Al(0.3)Ga(0.7)N cap layer, were used for fabricating the HEMT sensors. The gate area of the pH, chloride ion, and glucose detection was immobilized with scandium oxide (Sc(2)O(3)), silver chloride (AgCl) thin film, and zinc oxide (ZnO) nanorods, respectively. The Sc(2)O(3)-gated sensor could detect the pH of solutions ranging from 3 to 10 with a resolution of approximately 0.1 pH. A chloride ion detection limit of 10(-8) M was achieved with a HEMT sensor immobilized with the AgCl thin film. The drain-source current of the ZnO nanorod-gated AlGaN/GaN HEMT sensor immobilized with glucose oxidase showed a rapid response of less than 5 seconds when the sensor was exposed to the target glucose in a buffer with a pH value of 7.4. The sensor could detect a wide range of concentrations from 0.5 nM to 125 microM. There is great promise for using HEMT-based sensors to enhance the detection sensitivity for glucose detection in EBC. Depending on the immobilized material, HEMT-based sensors can be used for sensing different materials. These electronic detection approaches with rapid response and good repeatability show potential for the investigation of airway pathology. The devices can also be integrated into a wireless data transmission system for remote monitoring applications. This sensor technology could use the exhaled breath condensate to measure the glucose concentration for diabetic applications. 2010 Diabetes Technology Society.

Blood perfusion and pH monitoring in organs by laser-induced fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Vari, Sandor G.; Papazoglou, Theodore G.; Pergadia, Vani R.; Stavridi, Marigo; Snyder, Wendy J.; Papaioannou, Thanassis; Duffy, J. T.; Weiss, Andrew B.; Thomas, Reem; Grundfest, Warren S.

1994-01-01

Sensitivity of laser-induced fluorescence spectroscopy (LIFS) in detecting a change in tissue pH, and blood perfusion was determined. Rabbits were anesthetized, paralyzed, and mechanically ventilated. The arterial and venous blood supplies of the kidney were isolated and ligated to alter the perfusion. The femoral artery was cannulated to extract samples for blood gas analysis. A 308-nm XeCl was used as an excitation source. A 600 micrometers core diameter fiber was used for fluorescence acquisition, and the spectra analyzed by an optical multichannel analyzer (EG & G, OMA III). the corresponding intensity ratio R equals INADH / ICOLL was used as an index for respiratory acidosis. Blood perfusion was assessed using the following algorithm: (IELAS minus ICOLL) divided by (INADH minus ICOLL). The intensity ratio linearly decreased with the reduction of blood perfusion. When we totally occluded the artery the ratio decreased tenfold when compared to the ratio of a fully perfused kidney. Results of monitoring blood acidosis by laser-induced fluorescence spectroscopy shows a significant trend between pH and intensity ratio. Since all the slopes were negative, there is an obvious significant correlation between the pH and NADH.COLLAGEN RATIO. Blue-light-induced fluorescence measurements and ratio fluorometry is a sensitive method for monitoring blood perfusion and acidity or alkalinity of an organ.

Subsurface Treatment of Domestic Wastewater Using Single Domicile Constructed Wetlands

NASA Astrophysics Data System (ADS)

Aseltyne, T.; Steer, D.; Fraser, L.

2001-05-01

Analysis of one year of input versus output water quality monitoring data from nine household wastewater treatment wetlands in western Ohio indicates that these systems substantially reduce effluent loads delivered to the local watershed. Overall performance as measured by output water quality improvement varies widely between the nine systems despite their close proximity and identical design. These three-cell systems (septic tank with 2 subsurface wetland cells) are found to reduce biological oxygen demand (BOD) 70-98%, fecal coliform 60-99.9%, NH3 29-97%, Phosphorus 21-99.9% and total suspended solids (TSS) up to 97%. NO3/NO2 readings were only taken at the second wetland cell, but show that NO3/NO2 levels are at 0.005-5.01 mg/l and well below the USEPA standards for discharge from a wetland. On average, the pH of the wastewater increases from 6.6 at the septic tank to 8.7 at the wetland output. Nearly all the monitoring data indicate clear decreases in nutrient loads and bacteria though individual systems are found to non-systematically fail to meet EPA discharge guidelines for one or more of the monitored loads. Preliminary analysis of the data indicates a decrease in overall efficiency of the wetlands in April that may be related to seasonal factors. These systems will be monitored for the next three years in order to relate changing performance trends to seasonal variability.

A System Approach to Adaptive Multi-Modal Sensor Designs

DTIC Science & Technology

2010-02-01

afosr.af.mil> Prepared for Air Force Office of Scientific Research under Award FA9550-08-1-0199 February 2010 The City College of New York...York, NY 10031 9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM(S) Dr. Douglas Cochran AFOSR Air ...RIT. We would also like to thank Dr. Erik Blasch at the Air Force Research Laboratory (AFRL/RYAA) for his collaboration when our PhD student Mr

Evaluation of an Interdigitated Gate Electrode Field-Effect Transistor (IGEFET) for In Situ Resin Cure Monitoring

DTIC Science & Technology

1991-12-01

School of Engineering, Air Force Institute of Technology, Wright-Patterson AFB OH, October 1988. 8. Billmeyer, Fred W., Jr. Textbook of Polymer Science...448-453 (April 1989). 10. Sheppard, Norman Fred , Jr. Dielectric Analysis of the Cure of Thermosetting Epoxy/Amine Systems. PhD Dissertation...Viscosity and Chemical Changes During Polymerization," American Chemical Society Symposium Series on Photophysics of Polymers, edited by C. E. Hoyle and J. M

Use of the Photo-Electromyogram to Objectively Diagnose and Monitor Treatment of Post-TBI Light Sensitivity

DTIC Science & Technology

2013-10-01

Eye Clinic are being seen by the PI (Randy Kardon MD PhD) in his VA and University of Iowa neuro -ophthalmology clinics. These patients are being...using the DSI wireless data transmission system. We have implanted a functional transmitter into a subcutaneous pocket beyond the scapulae on the...implant more so than smaller mice. Figure 7. Recovery of mouse chronically implanted with subcutaneous EMG electrodes and transmitter . There was

Spatially monitoring oxygen level in 3D microfabricated cell culture systems using optical oxygen sensing beads

PubMed Central

Wang, Lin; Acosta, Miguel A.; Leach, Jennie B.; Carrier, Rebecca L.

2013-01-01

Capability of measuring and monitoring local oxygen concentration at the single cell level (tens of microns scale) is often desirable but difficult to achieve in cell culture. In this study, biocompatible oxygen sensing beads were prepared and tested for their potential for real-time monitoring and mapping of local oxygen concentration in 3D micro-patterned cell culture systems. Each oxygen sensing bead is composed of a silica core loaded with both an oxygen sensitive Ru(Ph2phen3)Cl2 dye and oxygen insensitive Nile blue reference dye, and a poly-dimethylsiloxane (PDMS) shell rendering biocompatibility. Human intestinal epithelial Caco-2 cells were cultivated on a series of PDMS and type I collagen based substrates patterned with micro-well arrays for 3 or 7 days, and then brought into contact with oxygen sensing beads. Using an image analysis algorithm to convert florescence intensity of beads to partial oxygen pressure in the culture system, tens of microns-size oxygen sensing beads enabled the spatial measurement of local oxygen concentration in the microfabricated system. Results generally indicated lower oxygen level inside wells than on top of wells, and local oxygen level dependence on structural features of cell culture surfaces. Interestingly, chemical composition of cell culture substrates also appeared to affect oxygen level, with type-I collagen based cell culture systems having lower oxygen concentration compared to PDMS based cell culture systems. In general, results suggest that oxygen sensing beads can be utilized to achieve real-time and local monitoring of micro-environment oxygen level in 3D microfabricated cell culture systems. PMID:23443975

Spatially monitoring oxygen level in 3D microfabricated cell culture systems using optical oxygen sensing beads.

PubMed

Wang, Lin; Acosta, Miguel A; Leach, Jennie B; Carrier, Rebecca L

2013-04-21

Capability of measuring and monitoring local oxygen concentration at the single cell level (tens of microns scale) is often desirable but difficult to achieve in cell culture. In this study, biocompatible oxygen sensing beads were prepared and tested for their potential for real-time monitoring and mapping of local oxygen concentration in 3D micro-patterned cell culture systems. Each oxygen sensing bead is composed of a silica core loaded with both an oxygen sensitive Ru(Ph2phen3)Cl2 dye and oxygen insensitive Nile blue reference dye, and a poly-dimethylsiloxane (PDMS) shell rendering biocompatibility. Human intestinal epithelial Caco-2 cells were cultivated on a series of PDMS and type I collagen based substrates patterned with micro-well arrays for 3 or 7 days, and then brought into contact with oxygen sensing beads. Using an image analysis algorithm to convert florescence intensity of beads to partial oxygen pressure in the culture system, tens of microns-size oxygen sensing beads enabled the spatial measurement of local oxygen concentration in the microfabricated system. Results generally indicated lower oxygen level inside wells than on top of wells, and local oxygen level dependence on structural features of cell culture surfaces. Interestingly, chemical composition of cell culture substrates also appeared to affect oxygen level, with type-I collagen based cell culture systems having lower oxygen concentration compared to PDMS based cell culture systems. In general, results suggest that oxygen sensing beads can be utilized to achieve real-time and local monitoring of micro-environment oxygen level in 3D microfabricated cell culture systems.

Low Cost Real Time Autonomous Remote Monitoring Platform

NASA Astrophysics Data System (ADS)

Rodríguez, J. R.; Maldonado, P. M.; Pierson, J. J.; Harris, L.

2016-02-01

Environmental scientists have a need for gathering multiple parameters during specific time periods to answer their research questions. Most available monitoring systems are very expensive and closed systems, which limits the potential to scale up research projects. We developed a low cost, autonomous, real-time monitoring platform that is both open hardware/software and easy to build, deploy, manage and maintain. The hardware is built with off-the-shelf components and a credit card sized computer called Raspberry Pi, running an open source operating (Raspbian). The system runs off a set of batteries and a solar panel, which makes it ideal for remote locations. The software is divided into three parts: 1) a framework for abstracting the sensors (initializing, pooling and communications) designed in python and using a fully object-oriented design, making it easy for new sensor to be added with minimal code changes, 2) a web front end for managing the entire system, 3) a data store (database) framework for local and remote data retrieval and reporting services. Connectivity to the system can be accomplished through a Wi-Fi or cellular Internet connection. Scientists are being forced to do more with less, in response our platform will provide them with a flexible system that can improve the process of data gathering with an accessible, modular, low-cost, and efficient monitoring system. Currently, we have the required permits from the Department of Natural Resources in Puerto Rico to deploy the platform at the Laguna Grande Bioluminescence Lagoon in Fajardo, PR. This station will include probes for pH, DO, Conductivity and water temperature.

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

PubMed

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 water-soluble rhodamine B-derived fluorescent probe for pH monitoring and imaging in acidic regions

NASA Astrophysics Data System (ADS)

Cui, Peng; Jiang, Xuekai; Sun, Junyong; Zhang, Qiang; Gao, Feng

2017-06-01

A structurally simple, water-soluble rhodamine-derivatived fluorescent probe, which is responsive to acidic pH, was conveniently synthesized via a one-step condensation reaction of rhodamine B hydrazide and 4-formybenzene-1,3-disulfonate. As a stable and highly sensitive pH sensor, the probe displays an approximately 50-fold fluorescence enhancement over the pH range of 7.16-4.89 as the structure of probe changes from spirocyclic (weak fluorescent) to ring-open (strong fluorescent) with decreasing pH. The synthesized fluorescent probe is applied to the detection of pH changes in vitro and in vivo bioimaging of immortalized gastric cancer cells, with satisfactory results.

Local pH Monitoring of Small Cluster of Cells using a Fiber-Optic Dual-Core Micro-Probe.

PubMed

Chen, Sisi; Yang, Qingbo; Xiao, Hai; Shi, Honglan; Ma, Yinfa

2017-03-31

Biological studies of tissues and cells have enabled numerous discoveries, but these studies still bear potential risks of invalidation because of cell heterogeneity. Through high-accuracy techniques, recent studies have demonstrated that discrepancies do exist between the results from low-number-cell studies and cell-population-based results. Thus the urgent need to re-evaluate key principles on limited number of cells has been provoked. In this study, a novel designed dual-core fiber-optic pH micro-probe was fabricated and demonstrated for niche environment pH sensing with high spatial resolution. An organic-modified silicate (OrMoSils) sol-gel thin layer was functionalized by entrapping a pH indicator, 2', 7'-Bis (2-carbonylethyl)-5(6)-carboxyfluorescein (BCECF), on a ~70 μm sized probe tip. Good linear correlation between fluorescence ratio of I 560 nm /I 640 nm and intercellular pH values was obtained within a biological-relevant pH range from 6.20 to 7.92 (R 2 = 0.9834), and with a pH resolution of 0.035 ± 0.005 pH units. The probe's horizontal spatial resolution was demonstrated to be less than 2mm. Moreover, the probe was evaluated by measuring the localized extracellular pH changes of cultured human lung cancer cells (A549) when exposed to titanium dioxide nanoparticles (TiO 2 NPs). Results showed that the probe has superior capability for fast, local, and continual monitoring of a small cluster of cells, which provides researchers a fast and accurate technique to conduct local pH measurements for cell heterogeneity-related studies.

Mediator-assisted decolorization and detoxification of textile dyes/dye mixture by Cyathus bulleri laccase.

PubMed

Chhabra, Meenu; Mishra, Saroj; Sreekrishnan, T R

2008-12-01

Laccase from basidiomycete fungus Cyathus bulleri was evaluated for its ability to decolorize a number of reactive and acidic dyes in the presence of natural and synthetic mediators. The extent of decolorization was monitored at different mediator/dye concentrations and incubation time. Among the synthetic mediators, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) was effective at low mediator/dye ratios and resulted in 80-95% decolorization at rates that varied from 226 +/- 4 nmol min(-1) mg(-1) for Reactive Orange 1 to 1,333 +/- 15 nmol min(-1) mg(-1) for Reactive Red 198. Other synthetic mediators like 1-hydroxybenzotriazole and violuric acid showed both concentration- and time-dependent increases in percent decolorization. Natural mediators like vanillin, on the other hand, were found to be less effective on all the dyes except Reactive Orange 1. Computed rates of decolorization were about twofold lower than that with ABTS. The laccase-ABTS system also led to nearly 80% decolorization for the simulated dye mixture. No clear correlation between laccase activity on the mediator and its ability to decolorize dyes was found, but pH had a significant effect: Optimum pH for decolorization coincided with the optimum pH for mediator oxidation. The treated samples were also evaluated for toxicity in model microbial systems. The laccase-mediator system appears promising for treatment of textile wastewaters.

Proton mediated control of biochemical reactions with bioelectronic pH modulation

DOE PAGES

Deng, Yingxin; Miyake, Takeo; Keene, Scott; ...

2016-04-07

In Nature, protons (H +) can mediate metabolic process through enzymatic reactions. Examples include glucose oxidation with glucose dehydrogenase to regulate blood glucose level, alcohol dissolution into carboxylic acid through alcohol dehydrogenase, and voltage-regulated H + channels activating bioluminescence in firefly and jellyfish. Artificial devices that control H + currents and H + concentration (pH) are able to actively influence biochemical processes. Here, we demonstrate a biotransducer that monitors and actively regulates pH-responsive enzymatic reactions by monitoring and controlling the flow of H + between PdH x contacts and solution. The present transducer records bistable pH modulation from an “enzymaticmore » flip-flop” circuit that comprises glucose dehydrogenase and alcohol dehydrogenase. Furthermore, the transducer also controls bioluminescence from firefly luciferase by affecting solution pH.« less

Proton mediated control of biochemical reactions with bioelectronic pH modulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deng, Yingxin; Miyake, Takeo; Keene, Scott

In Nature, protons (H +) can mediate metabolic process through enzymatic reactions. Examples include glucose oxidation with glucose dehydrogenase to regulate blood glucose level, alcohol dissolution into carboxylic acid through alcohol dehydrogenase, and voltage-regulated H + channels activating bioluminescence in firefly and jellyfish. Artificial devices that control H + currents and H + concentration (pH) are able to actively influence biochemical processes. Here, we demonstrate a biotransducer that monitors and actively regulates pH-responsive enzymatic reactions by monitoring and controlling the flow of H + between PdH x contacts and solution. The present transducer records bistable pH modulation from an “enzymaticmore » flip-flop” circuit that comprises glucose dehydrogenase and alcohol dehydrogenase. Furthermore, the transducer also controls bioluminescence from firefly luciferase by affecting solution pH.« less

Imaging pH and oxygen at the soil-root interface by planar optodes: a challenging technology to study dynamic rhizosphere processes.

NASA Astrophysics Data System (ADS)

Daudin, Gabrielle; Oburger, Eva; Schmidt, Hannes; Borisov, Sergey; Pradier, Céline; Jourdan, Christophe; Marsden, Claire; Obermaier, Daniela; Woebken, Dagmar; Richter, Andreas; Wenzel, Walter; Hinsinger, Philippe

2017-04-01

Roots do not only take up water and nutrients from surrounding soil but they also release a wide range of exudates, such as low molecular weight organic compounds, CO2 or protons. Root-soil interactions trigger heterogeneous rhizosphere processes based on differences in root activity along the root axis and with distance from the root surface. Elucidating their temporal and spatial dynamics is of crucial importance for a better understanding of these interrelated biogeochemical processes in the rhizosphere. Therefore, monitoring key parameters at a fine scale and in a non-invasive way at the root-soil interface is essential. Planar optodes are an emerging technology that allows in situ and non-destructive imaging of mainly pH, CO2 and O2. Originated in limnology, planar optodes have recently been applied to soil-root systems in laboratory conditions. This presentation will highlight advantages and challenges of using planar optodes to image pH and O2 dynamics in the rhizosphere, focusing on two RGB (red-green-blue) approaches: a commercially available system (PreSens) and a custom-made one. Important insights into robustness, accuracy, potentials and limitations of the two systems applied to different laboratory/greenhouse-based experimental conditions (flooded and aerobic rhizobox systems, plant species) will be addressed. Furthermore, challenges of optode measurements in the field, including a first case study with Eucalyptus grandis in Brazil, will be discussed.

Experimental investigations of the effect the electrical conductivity of medium has on the performance of pH meters

NASA Astrophysics Data System (ADS)

Rodionov, A. K.; Karashchuk, S. A.

2013-07-01

Results from tests of pH meters carried out in ammonia media having low electric conductivity (less than 5.0 μS/cm) are presented. The check media for the tests were prepared in a special manner the use of which makes it possible to reproduce the pH value of solution with an error not exceeding ˜0.04pH in the range of electrical conductivities above 0.1 μS/cm. The instrument measurement error was determined at different electrical conductivities of medium. Different electrodes were tested, the majority of which were domestically produced ones intended for general industrial applications. Some results were also obtained for one dedicated electrode from a foreign manufacturer. The test results show that the instrument gives a biased pH value for such media. The bias has a random value, which nonetheless is stable in the majority of cases, depends on the electrical conductivity of medium being monitored, and may be quite essential for small electrical conductivities (0.5pH or more). A conclusion is drawn about the need to calibrate the instruments with respect to standard media having electrical conductivity close to that of the medium being monitored. Analytic relations characterizing the check media used fort tests (check solutions) are presented.

Laboratory investigations of stable carbon and oxygen isotope ratio data enhance monitoring of CO2 underground

NASA Astrophysics Data System (ADS)

Barth, Johannes A. C.; Myrttinen, Anssi; Becker, Veith; Nowak, Martin; Mayer, Bernhard

2014-05-01

Stable carbon and oxygen isotope data play an important role in monitoring CO2 in the subsurface, for instance during carbon capture and storage (CCS). This includes monitoring of supercritical and gaseous CO2 movement and reactions under reservoir conditions and detection of potential CO2 leakage scenarios. However, in many cases isotope data from field campaigns are either limited due to complex sample retrieval or require verification under controlled boundary conditions. Moreover, experimentally verified isotope fractionation factors are also accurately known only for temperatures and pressures lower than commonly found in CO2 reservoirs (Myrttinen et al., 2012). For this reason, several experimental series were conducted in order to investigate effects of elevated pressures, temperatures and salinities on stable carbon and oxygen isotope changes of CO2 and water. These tests were conducted with a heateable pressure device and with glass or metal gas containers in which CO2 reacted with fluids for time periods of hours to several weeks. The obtained results revealed systematic differences in 13C/12C-distributions between CO2 and the most important dissolved inorganic carbon (DIC) species under reservoir conditions (CO2(aq), H2CO3 and HCO3-). Since direct measurements of the pH, even immediately after sampling, were unreliable due to rapid CO2 de-gassing, one of the key results of this work is that carbon isotope fractionation data between DIC and CO2 may serve to reconstruct in situ pH values. pH values reconstructed with this approach ranged between 5.5 and 7.4 for experiments with 60 bars and up to 120 °C and were on average 1.4 pH units lower than those measured with standard pH electrodes directly after sampling. In addition, pressure and temperature experiments with H2O and CO2 revealed that differences between the oxygen isotope ratios of both phases depended on temperature, water-gas ratios as well as salt contents of the solutions involved. Such systematic knowledge of the extent of oxygen isotope fractionation between H2O and CO2 can help to reconstruct equilibration times, fluid-CO2 ratios as well as temperature and salinity conditions. Isotope results from systematic laboratory studies and the information they provide for assessing in situ reservoir conditions can be transferred to field applications concerning integrity of CO2 reservoirs. They can also apply to natural systems and other industrial uses that involve monitoring of gases in the subsurface under similar pressure and temperature conditions. Reference: Myrttinen, A., Becker, V., Barth, J.A.C., 2012. A review of methods used for equilibrium isotope fractionation investigations between dissolved inorganic carbon and CO2. Earth-Science Reviews, 115(3): 192-199.

Ocean acidification buffering effects of seagrass in Tampa Bay

USGS Publications Warehouse

Yates, Kimberly K.; Moyer, Ryan P.; Moore, Christopher; Tomasko, David A.; Smiley, Nathan A.; Torres-Garcia, Legna; Powell, Christina E.; Chappel, Amanda R.; Bociu, Ioana; Smiley, Nathan; Torres-Garcia, Legna M.; Powell, Christina E.; Chappel, Amanda R.; Bociu, Ioana

2016-01-01

The Intergovernmental Panel on Climate Change has identified ocean acidification as a critical threat to marine and estuarine species in ocean and coastal ecosystems around the world. However, seagrasses are projected to benefit from elevated atmospheric pCO2, are capable of increasing seawater pH and carbonate mineral saturation states through photosynthesis, and may help buffer against the chemical impacts of ocean acidification. Additionally, dissolution of carbonate sediments may also provide a mechanism for buffering seawater pH. Long-term water quality monitoring data from the Environmental Protection Commission of Hillsborough County indicates that seawater pH has risen since the 1980‘s as seagrass beds have continued to recover since that time. We examined the role of seagrass beds in maintaining and elevating pH and carbonate mineral saturation state in northern and southern Tampa Bay where the percent of carbonate sediments is low (<3%) and high (>40%), respectively. Basic water quality and carbonate system parameters (including pH, total alkalinity, dissolved inorganic carbon, partial pressure of CO2, and carbonate mineral saturation state) were measured over diurnal time periods along transects (50-100 m) including dense and sparse Thalassia testudinum. seagrass beds, deep edge seagrass, and adjacent bare sand bottom. Seagrass density and productivity, sediment composition and hydrodynamic parameters were also measured, concurrently. Results indicate that seagrass beds locally elevate pH by up to 0.5 pH unit and double carbonate mineral saturation states relative to bare sand habitats. Thus, seagrass beds in Tampa Bay may provide refuge for marine organisms from the impacts of ocean acidification.

X ray attenuation measurements for high-temperature materials characterization and in-situ monitoring of damage accumulation. Ph.D. Thesis - Cleveland State Univ., 1991

NASA Technical Reports Server (NTRS)

Baaklini, George Y.

1992-01-01

The scope of this dissertation is to develop and apply x ray attenuation measurement systems that are capable of: (1) characterizing density variations in high-temperature materials, e.g., monolithic ceramics, ceramic and intermetallic matrix composites, and (2) noninvasively monitoring damage accumulation and failure sequences in ceramic matrix composites under room temperature tensile testing. This dissertation results in the development of: (1) a point scan digital radiography system, and (2) an in-situ x ray material testing system. Radiographic evaluation before, during, and after loading shows the effect of preexisting volume flaws on the fracture behavior of composites. Results show that x ray film radiography can monitor damage accumulation during tensile loading. Matrix cracking, fiber matrix debonding, fiber bridging, and fiber pullout are imaged throughout the tensile loading of the specimens. Further in-situ radiography is found to be a practical technique for estimating interfacial shear strength between the silicon carbide fibers and the reaction bonded silicon nitride matrix. It is concluded that pretest, in-situ, and post test x ray imaging can provide for greater understanding of ceramic matrix composite mechanical behavior.

A composite reactor with wetted-wall column for mineral carbonation study in three-phase systems.

PubMed

Zhu, Chen; Yao, Xizhi; Zhao, Liang; Teng, H Henry

2016-11-01

Despite the availability of various reactors designed to study gas-liquid reactions, no appropriate devices are available to accurately investigate triple-phased mineral carbonation reactions involving CO 2 gas, aqueous solutions (containing divalent cations), and carbonate minerals. This report presents a composite reactor that combines a modified conventional wetted-wall column, a pH control module, and an attachment to monitor precipitation reactions. Our test and calibration experiments show that the absorption column behaved largely in agreement with theoretical predictions and previous observations. Experimental confirmation of CO 2 absorption in NaOH and ethanolamine supported the effectiveness of the column for gas-liquid interaction. A test run in the CO 2 -NH 3 -MgCl 2 system carried out for real time investigation of the relevant carbonation reactions shows that the reactor's performance closely followed the expected reaction path reflected in pH change, the occurrence of precipitation, and the rate of NH 3 addition, indicating the appropriateness of the composite device in studying triple-phase carbonation process.

Clinical features and prevalence of gastroesophageal reflux disease in infants attending a pediatric gastroenterology reference service.

PubMed

Koda, Yu Kar Ling; Ozaki, Marcos J; Murasca, Kelly; Vidolin, Eliana

2010-01-01

In infants, it is not always easy to distinguish between pathological and physiological gastroesophageal reflux based only on clinical criteria. In Brazil, studies about gastroesophageal reflux disease in infants are few and are even rare those that used prolonged esophageal pH monitoring for its evaluation. To describe the clinical features of gastroesophageal reflux disease and to determine its prevalence in infants with gastroesophageal reflux attending a tertiary Pediatric Gastroenterology Service and submitted to esophageal pH monitoring for investigation. Descriptive study in 307 infants in whom esophageal pH monitoring (Mark III Digitrapper, Synectics Medical AB, Sweden) was performed during the period December, 1998-December, 2008. The clinical features studied were age group (1-12 months and 13-24 months), and clinical manifestations that motivated the indication of pH monitoring. One hundred twenty-four (40.4%) were female and 183 (59.6%) male with mean age 12.2 +/- 6.2 months (1-23 months). The prevalence of gastroesophageal reflux disease was 18.2% (56/307). One hundred forty-eight (48.2%) were 1-12 months old and 159 (51.8%), 13-24 months. No significant difference was found between the prevalence of these two age groups (P = 0.3006). Gastroesophageal reflux disease was more frequent in those with digestive manifestations (24.2%), crisis of cyanosis/apnea (23.8%) and mixed manifestations (21.5%). Respiratory manifestations were the most frequent indication (39.1%) of pH monitoring. However, the prevalence of gastroesophageal reflux disease was lower (12.5%) in this group compared with in those with digestive manifestations (P = 0.0574), crisis of cyanosis/apnea (P = 0.0882) and mixed manifestations (P = 0.1377). All infants that presented clinical manifestations as crisis of cyanosis/apnea and abnormal pH-metry were < 3 months of age. In our Service, the prevalence of gastroesophageal reflux disease associated with acid reflux in infants revealed elevated. Infants with crisis of cyanosis/apnea constitute risk population for gastroesophageal reflux disease in which diagnostic investigation needs to be considered.

In-situ Eh sensor measurement and calibration: application to seafloor observatories

NASA Astrophysics Data System (ADS)

Ding, K.; Seyfried, W. E.; Tan, C.

2013-12-01

Eh measurement is often used with manned submersible and AUV assets as an effective way to detect and locate seafloor hydrothermal activity. Eh can be fundamentally and sensitively linked to dissolved H 2 , which, in turn, serves as a key constraint on subseafloor redox reactions. Moreover, Eh is now being increasingly relied on for event detection and process monitoring efforts intrinsic to cabled seafloor observatories. Due to seawater interaction with electrochemical components fundamental to the operation of the Eh sensor, however, the quality and reliability of the measurements are often compromised by signal drift, especially when the sensor is used for long term deployment. To solve this problem, a calibration protocol was developed and added to our previously constructed pH 'calibrator'. Thus, the integrated electrochemical system now permits the combined in-situ measurement and calibration of pH and Eh of seafloor hydrothermal fluids. Key aspects of the design for this calibration system are: (1) the sensing electrodes can be kept preserved in fluid of known pH, Eh and NaCl concentration prior to use, thereby preventing deterioration of electrode response characteristics by chemical and biological activity; (2) the system consists of valves and pumps for flow control, and therefore can be operated remotely with power from the seafloor cabled observatory, or as a stand-alone device, using battery power for shorter-term deployments. In both cases, standardization with on-board fluids of known redox, pH, and NaCl activity can be activated at any time, providing enhanced reliability (3) the current development is aimed at deep sea environments, cold seeps, and hydrothermal diffuse flow fluids at the temperatures up to 100°C and depths up to 4500 m. The in-situ operation is especially well-suited for use with cabled observatory for real time intervention and event response owing to enabled power supply and two way communications. Field tests have been conducted extensively during one Alvin cruise at EPR 9°N, and one Jason-II cruise at MAR (Lost city, 30°N). In addition to these submersible deployments, profile measurements using ship wench system were made from the sea-surface to depths to more than 3000 m. The remote operation tests were carried out with a direct connection though MARS seafloor cabled observatory at the depth of 880 m for a period of more than two months. During these deployments, the standard solutions with O2 concentration of room saturation matched with seawater salinity and know pH values were used. The results indicate the effectiveness of these concepts and design for conducting in-situ calibration enhanced Eh measurement and monitoring covering the operational conditions from normal seawater with relatively oxidizing environment to reducing condition in low temperature hydrothermal diffuse systems. The results and detailed discussion will be presented in this presentation.

Chemical hazards from acid crater lakes

NASA Astrophysics Data System (ADS)

van Bergen, M. J.; Sumarti, S.; Heikens, A.; Bogaard, T. A.; Hartiyatun, S.

2003-04-01

Acid crater lakes, which are hosted by a considerable number of active volcanoes, form a potential threat for local ecosystems and human health, as they commonly contain large amounts of dissolved chemicals. Subsurface seepage or overflow can lead to severe deterioration of the water quality of rivers and wells, as observations around several of these volcanoes have shown. The Ijen crater lake in East Java (Indonesia) is a striking example, as this reservoir of hyperacid (pH<0.5) sulphate, chloride and fluoride-rich water is the source of a ca. 50 km long acid river that transports substantial quantities of potentially toxic elements. A downstream trend of increasing pH from <1 to 2.5-4 is largely due to dilution with moderately acid springs (pH= ca. 4) and neutral tributaries (pH= ca. 7) inside the Ijen caldera. Geochemical controls that regulate element transport are subject to seasonal fluctuations in rainfall. Long-term monitoring has shown that fluoride levels pose some of the most severe environmental threats. Its concentration decreases from ca. 1300 mg/kg in the lake to ca. 10 mg/kg in a coastal area downstream, where virtually all of the river water is used for irrigating rice fields and other cropland. Apart from serious problems for agriculture, our survey of 55 drinking water wells in the irrigation area shows that 50% contain fluoride above the 1.5 ppm WHO limit, in line with the observation that dental fluorosis is widespread among the ca. 100,000 residents of the area. A conspicuous spatial correlation between fluoride concentrations and the irrigation system suggest that long-term (century) infiltration of irrigation water may have affected the quality of groundwater. Fluorosis is also a problem in some villages within the caldera, where well water sources may have a more direct subsurface connection with the lake system. From our observations we conclude that water-quality monitoring is especially needed for health reasons in volcanic areas where volatile elements, derived from passively degassing magma, are intercepted by (sub) surface water bodies.

BIOTEX--biosensing textiles for personalised healthcare management.

PubMed

Coyle, Shirley; Lau, King-Tong; Moyna, Niall; O'Gorman, Donal; Diamond, Dermot; Di Francesco, Fabio; Costanzo, Daniele; Salvo, Pietro; Trivella, Maria Giovanna; De Rossi, Danilo Emilio; Taccini, Nicola; Paradiso, Rita; Porchet, Jacque-André; Ridolfi, Andrea; Luprano, Jean; Chuzel, Cyril; Lanier, Thierry; Revol-Cavalier, Frdéric; Schoumacker, Sébastien; Mourier, Véronique; Chartier, Isabelle; Convert, Reynald; De-Moncuit, Henri; Bini, Christina

2010-03-01

Textile-based sensors offer an unobtrusive method of continually monitoring physiological parameters during daily activities. Chemical analysis of body fluids, noninvasively, is a novel and exciting area of personalized wearable healthcare systems. BIOTEX was an EU-funded project that aimed to develop textile sensors to measure physiological parameters and the chemical composition of body fluids, with a particular interest in sweat. A wearable sensing system has been developed that integrates a textile-based fluid handling system for sample collection and transport with a number of sensors including sodium, conductivity, and pH sensors. Sensors for sweat rate, ECG, respiration, and blood oxygenation were also developed. For the first time, it has been possible to monitor a number of physiological parameters together with sweat composition in real time. This has been carried out via a network of wearable sensors distributed around the body of a subject user. This has huge implications for the field of sports and human performance and opens a whole new field of research in the clinical setting.

Host-pathogen redox dynamics modulate Mycobacterium tuberculosis pathogenesis.

PubMed

Pacl, Hayden T; Reddy, Vineel P; Saini, Vikram; Chinta, Krishna C; Steyn, Adrie J C

2018-07-01

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, encounters variable and hostile environments within the host. A major component of these hostile conditions is reductive and oxidative stresses induced by factors modified by the host immune response, such as oxygen tension, NO or CO gases, reactive oxygen and nitrogen intermediates, the availability of different carbon sources and changes in pH. It is therefore essential for Mtb to continuously monitor and appropriately respond to the microenvironment. To this end, Mtb has developed various redox-sensitive systems capable of monitoring its intracellular redox environment and coordinating a response essential for virulence. Various aspects of Mtb physiology are regulated by these systems, including drug susceptibility, secretion systems, energy metabolism and dormancy. While great progress has been made in understanding the mechanisms and pathways that govern the response of Mtb to the host's redox environment, many questions in this area remain unanswered. The answers to these questions are promising avenues for addressing the tuberculosis crisis.

Monitoring of crustal movements in the San Andreas fault zone by a satellite-borne ranging system. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Kumar, M.

1976-01-01

The Close Grid Geodynamic Measurement System is conceived as an orbiting ranging device with a ground base grid of reflectors or transponders (spacing 1.0 to 30 km), which are projected to be of low cost (maintenance free and unattended), and which will permit the saturation of a local area to obtain data useful to monitor crustal movements in the San Andreas fault zone. The system includes a station network of 75 stations covering an area between 36 deg N and 38 deg N latitudes, and 237 deg E and 239 deg E longitudes, with roughly half of the stations on either side of the faults. In addition, the simulation of crustal movements through the introduction of changes in the relative positions between grid stations, weather effect for intervisibility between satellite and station and loss of observations thereof, and comparative evaluation of various observational scheme-patterns have been critically studied.

Monitoring fetal pH by telemetry

NASA Technical Reports Server (NTRS)

Blum, A.; Donahoe, T.; Jhabvala, M. D.; Ryan, W.

1980-01-01

Telemetry unit has been developed for possible use in measuring scalp-tissue pH and heart rate of unborn infant. Unit radius data to receiver as much as 50 ft. away. Application exists during hours just prior to childbirth to give warning of problems that might require cesarean delivery.

Sensor capsule for diagnosis of gastric disorders

NASA Technical Reports Server (NTRS)

Holen, J. T.

1972-01-01

Motility and pH sensor capsule is developed to monitor gastric acidity, pressure, and temperature. Capsule does not interfere with digestion. Sensor is capsule which includes pH electrode, Pitran pressure transducer, and thermistor temperature sensor all potted in epoxy and enclosed in high density polyethylene sheath.

Sensitivity and specificity of the Gastrointestinal Short Form Questionnaire in diagnosis of gastroesophageal reflux disease.

PubMed

Teruel Sánchez-Vegazo, Carlos; Faro Leal, Vicenta; Muriel García, Alfonso; Mañas Gallardo, Norberto

2016-04-01

Gastrointestinal Short Form Questionnaire (GSFQ) is a questionnaire for gastroesophageal reflux disease (GERD) diagnosis, with a version in Spanish language, not yet compared to an objective test. To establish GSFQ diagnostic performance against 24-hour pH monitoring carried out in two tertiary care hospitals. Consecutive adult patients with typical GERD symptoms (heartburn, regurgitation) referred for pH monitoring fulfilled the GSFQ (score range 0-30, proportional to probability of GERD). Diagnosis of GERD was established when acid exposure time in distal esophagus was superior to 4.5% or symptom association probability was greater than 95%. Receiver-operator characteristic (ROC) curves were calculated and best cut-off score determined, with corresponding sensitivity, specificity and likelihood ratios (LR) (95% confidence interval for each). One hundred and fifty-two patients were included (59.9% women, age 47.9 ± 13.9; 97.4% heartburn; 71.3% regurgitation). pH monitoring was abnormal in 65.8%. Mean GSFQ score was 11.2 ± 6. Area under ROC was 56.5% (47.0-65.9%). Optimal cut-off score was 13 or greater: sensitivity 40% (30.3-50.3%), specificity 71.2% (56.9-82.9%), positive LR 1.39 (0.85-2.26) and negative LR 0.84 (0.67-1.07). Exclusion of questions 1 and 3 of the original GSFQ, easily interpreted as referred to dyspepsia and not GERD, improved only marginally the diagnostic performance: AUROC 59.1%. The GSFQ does not predict results of pH monitoring in patients with typical symptoms in a tertiary care setting.

Magnetic Resonance Characterization of Cardiac Adaptation and Myocardial Fibrosis in Pulmonary Hypertension Secondary to Systemic-To-Pulmonary Shunt.

PubMed

Pereda, Daniel; García-Lunar, Inés; Sierra, Federico; Sánchez-Quintana, Damián; Santiago, Evelyn; Ballesteros, Constanza; Encalada, Juan F; Sánchez-González, Javier; Fuster, Valentín; Ibáñez, Borja; García-Álvarez, Ana

2016-09-01

Pulmonary hypertension (PH) and right ventricular (RV) dysfunction are strong predictors of morbidity and mortality among patients with congenital heart disease. Early detection of RV involvement may be useful in the management of these patients. We aimed to assess progressive cardiac adaptation and quantify myocardial extracellular volume in an experimental porcine model of PH because of aorto-pulmonary shunt using cardiac magnetic resonance (CMR). To characterize serial cardiac adaptation, 12 pigs (aorto-pulmonary shunt [n=6] or sham operation [n=6]) were evaluated monthly with right heart catheterization, CMR, and computed tomography during 4 months, followed by pathology analysis. Extracellular volume by CMR in different myocardial regions was studied in 20 animals (aorto-pulmonary shunt [n=10] or sham operation [n=10]) 3 months after the intervention. All shunted animals developed PH. CMR evidenced progressive RV hypertrophy and dysfunction secondary to increased afterload and left ventricular dilatation secondary to volume overload. Shunt flow by CMR strongly correlated with PH severity, left ventricular end-diastolic pressure, and left ventricular dilatation. T1-mapping sequences demonstrated increased extracellular volume at the RV insertion points, the interventricular septum, and the left ventricular lateral wall, reproducing the pattern of fibrosis found on pathology. Extracellular volume at the RV insertion points strongly correlated with pulmonary hemodynamics and RV dysfunction. Prolonged systemic-to-pulmonary shunting in growing piglets induces PH with biventricular remodeling and myocardial fibrosis that can be detected and monitored using CMR. These results may be useful for the diagnosis and management of congenital heart disease patients with pulmonary overcirculation. © 2016 American Heart Association, Inc.

Evaluation of the effects of various culture condition on Cr (VI)reduction by Shewanella oneidensis MR-1 in a novel high-throughputmini-bioreactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Yinjie J.; Laidlaw, David; Gani, Kishen

2006-03-16

The growth and Cr(VI) reduction by Shewanella oneidensisMR-1 was examined using a mini-bioreactor system that independentlymonitors and controls pH, dissolved oxygen, and temperature for each ofits 24, 10-mL reactors. Independent monitoring and control of eachreactor in the cassette allows the exploration of a matrix ofenvironmental conditions known to influence S. oneidensis chromiumreduction. S. oneidensis MR-1 grew in minimal medium without amino acidor vitamin supplementation under aerobic conditions but required serineand glycine supplementation under anaerobic conditions. Growth wasinhibited by dissolved oxygen concentrations>80 percent. Lactatetransformation to acetate was enhanced by low concentration of dissolvedoxygen during the logarithmic growth phase. Between 11 andmore » 35oC, thegrowth rate obeyed the Arrhenius reaction rate-temperature relationship,with a maximum growth rate occurring at 35oC. S. oneidensis MR-1 was ableto grow over a wide range of pH (6-9). At neutral pH and temperaturesranging from 30-35oC, S. oneidensis MR-1 reduced 100 mu M Cr(VI) toCr(III) within 20 minutes in the exponential growth phase, and the growthrate was not affected by the addition of chromate; it reduced chromateeven faster at temperatures between 35 and 39oC. At low temperatures(<25oC), acidic (pH<6.5), or alkaline (pH>8.5) conditions, 100mu M Cr(VI) strongly inhibited growth and chromate reduction. Themini-bioreactor system enabled the rapid determination of theseparameters reproducibly and easily by performing very few experiments.Besides its use for examining parameters of interest to environmentalremediation, the device will also allow one to quickly assess parametersfor optimal production of recombinant proteins or secondarymetabolites« less

Sources of Nutrients to Nearshore Areas of a Eutrophic Estuary: Implications for Nutrient-Enhanced Acidification in Puget Sound

NASA Astrophysics Data System (ADS)

Pacella, S. R.

2016-02-01

Ocean acidification has recently been highlighted as a major stressor for coastal organisms. Further work is needed to assess the role of anthropogenic nutrient additions in eutrophied systems on local biological processes, and how this interacts with CO2 emission-driven acidification. This study sought to distinguish changes in pH caused by natural versus anthropogenically affected processes. We quantified the variability in water column pH attributable to primary production and respiration fueled by anthropogenically derived nitrogen in a shallow nearshore area. Two study sites were located in shallow subtidal areas of the Snohomish River estuary, a eutrophic system located in central Puget Sound, Washington. These sites were chosen due to the presence of heavy agricultural activity, urbanized areas with associated waste water treatment, as well as influence from deep, high CO2 marine waters transported through the Strait of Juan de Fuca and upwelled into the area during spring and summer. Data was collected from July-December 2015 utilizing continuous moorings and discrete water column sampling. Analysis of stable isotopes, δ15N, δ18O-NO3, δ15N-NH4, was used to estimate the relative contributions of anthropogenic versus upwelled marine nitrogen sources. Continuous monitoring of pH, dissolved oxygen, temperature, and salinity was conducted at both study sites to link changes in nutrient source and availability with changes in pH. We predicted that isotope data would indicate greater contributions of nitrogen from agriculture and wastewater rather than upwelling in the shallow, nearshore study sites. This study seeks to distinguish the relative magnitude of pH change stimulated by anthropogenic versus natural sources of nitrogen to inform public policy decisions in critically important nearshore ecosystems.

Real-Time monitoring of the eutrophication and hypoxia off the Changjiang Estuary

NASA Astrophysics Data System (ADS)

Chen, J. F.

2016-02-01

Inputs of anthropogenic nutrients and carbon dioxide-rich waters to the coastal waters can not only lead to eutrophication in the surface water and hypoxia in the bottom water, but also will enhance acidification of coastal water. In order to understand the details mechanism of concurrence of eutrophication and hypoxia in the Changjiang Estuary, a real time monitoring system has been established since 2010 under the support of Chinese National Key Technologies R&D Program and Chinese Marine Research Special Funds for Public Welfare Projects. The platforms of the monitoring system includes a 3-meter buoy with water column chain unit and a seabed mounted unit, the sensors includes those can detect wind speed and direction, air and water temperature, salinity, currents, PAR, DO, pH, nutrients, Chl a, turbidity and pCO2 etc.. Two highlights of our scientific findings will introduced in this presentation, one is how typhoon affected the coastal hypoxia (positive and negative), and the other is how fresh water input induced a algal bloom in the Changjiang Estuary in summer.

Development of a takeoff performance monitoring system. Ph.D. Thesis. Contractor Report, Jan. 1984 - Jun. 1985

NASA Technical Reports Server (NTRS)

Srivatsan, Raghavachari; Downing, David R.

1987-01-01

Discussed are the development and testing of a real-time takeoff performance monitoring algorithm. The algorithm is made up of two segments: a pretakeoff segment and a real-time segment. One-time imputs of ambient conditions and airplane configuration information are used in the pretakeoff segment to generate scheduled performance data for that takeoff. The real-time segment uses the scheduled performance data generated in the pretakeoff segment, runway length data, and measured parameters to monitor the performance of the airplane throughout the takeoff roll. Airplane and engine performance deficiencies are detected and annunciated. An important feature of this algorithm is the one-time estimation of the runway rolling friction coefficient. The algorithm was tested using a six-degree-of-freedom airplane model in a computer simulation. Results from a series of sensitivity analyses are also included.

Removal of phosphate from greenhouse wastewater using hydrated lime.

PubMed

Dunets, C Siobhan; Zheng, Youbin

2014-01-01

Phosphate (P) contamination in nutrient-laden wastewater is currently a major topic of discussion in the North American greenhouse industry. Precipitation of P as calcium phosphate minerals using hydrated lime could provide a simple, inexpensive method for retrieval. A combination of batch experiments and chemical equilibrium modelling was used to confirm the viability of this P removal method and determine lime addition rates and pH requirements for greenhouse wastewater of varying nutrient compositions. Lime: P ratio (molar ratio of CaMg(OH)₄: PO₄‒P) provided a consistent parameter for estimating lime addition requirements regardless of initial P concentration, with a ratio of 1.5 providing around 99% removal of dissolved P. Optimal P removal occurred when lime addition increased the pH from 8.6 to 9.0, suggesting that pH monitoring during the P removal process could provide a simple method for ensuring consistent adherence to P removal standards. A Visual MINTEQ model, validated using experimental data, provided a means of predicting lime addition and pH requirements as influenced by changes in other parameters of the lime-wastewater system (e.g. calcium concentration, temperature, and initial wastewater pH). Hydrated lime addition did not contribute to the removal of macronutrient elements such as nitrate and ammonium, but did decrease the concentration of some micronutrients. This study provides basic guidance for greenhouse operators to use hydrated lime for phosphate removal from greenhouse wastewater.

The Production Rate and Employment of Ph.D. Astronomers

NASA Astrophysics Data System (ADS)

Metcalfe, Travis S.

2007-05-01

As in many sciences, the production rate of new Ph.D. astronomers is decoupled from the global demand for trained scientists. As noted by Thronson (1991, PASP, 103, 90), overproduction appears to be built into the system, making the mathematical formulation of surplus astronomer production similar to that for industrial pollution models -- an unintended side effect of the process. Following Harris (1994, ASP Conf., 57, 12), I document the production of Ph.D. astronomers from 1990 to 2005 using the online Dissertation Abstracts database. To monitor the changing patterns of employment, I examine the number of postdoctoral, tenure-track, and other jobs advertised in the AAS Job Register during this same period. Although the current situation is clearly unsustainable, it was much worse a decade ago with nearly 7 new Ph.D. astronomers in 1995 for every new tenure-track job. While the number of new permanent positions steadily increased throughout the late 1990's, the number of new Ph.D. recipients gradually declined. After the turn of the century, the production of new astronomers leveled off, but new postdoctoral positions grew dramatically. There has also been recent growth in the number of non-tenure-track lecturer, research, and support positions. This is just one example of a larger cultural shift to temporary employment that is happening throughout society -- it is not unique to astronomy.

Comparative analysis of the outflow water quality of two sustainable linear drainage systems.

PubMed

Andrés-Valeri, V C; Castro-Fresno, D; Sañudo-Fontaneda, L A; Rodriguez-Hernandez, J

2014-01-01

Three different drainage systems were built in a roadside car park located on the outskirts of Oviedo (Spain): two sustainable urban drainage systems (SUDS), a swale and a filter drain; and one conventional drainage system, a concrete ditch, which is representative of the most frequently used roadside drainage system in Spain. The concentrations of pollutants were analyzed in the outflow of all three systems in order to compare their capacity to improve water quality. Physicochemical water quality parameters such as dissolved oxygen, total suspended solids, pH, electrical conductivity, turbidity and total petroleum hydrocarbons were monitored and analyzed for 25 months. Results are presented in detail showing significantly smaller amounts of outflow pollutants in SUDS than in conventional drainage systems, especially in the filter drain which provided the best performance.

Assessment of CO2-Induced Geochemical Changes in Soil/Mineral-Water Systems

NASA Astrophysics Data System (ADS)

Jeong, H. Y.; Choi, H. J.

2016-12-01

Although the storage of CO2 in deep geological formations is considered the most promising sequestration path, there is still a risk that it may leak into the atmosphere. To ensure the secure operation of CO2 storage sites, thus, it is necessary to implement CO2 leakage monitoring systems. Furthermore, the leakage may alter geochemical properties of overlying geological units to have adverse environmental consequences. By elucidating geochemical changes due to CO2 leakage, it is possible to develop effective CO2 monitoring techniques and predict the influence of CO2 leakage. A series of batch experiments were conducted to simulate CO2-induced geochemical changes in soil/mineral-water systems. Soil samples, obtained from Eumseong basin in Eumseong-gun, Chungcheongbuk-do, were dried for 6 hours at 60° and then divided into two size fractions: < 106 and 106-212 mm. Minerals including mica/illite, vermiculite, and feldspar were purchased and purified if necessary. Prior to batch experiments, soils and minerals were characterized for surface area, mineralogy, elemental composition, carbon and nitrogen contents, pH buffering capacity, and metal extractability. Batch experiments were initiated by reacting 100% CO2 atmosphere with aqueous suspensions of 120 g soils or 50 g minerals in 3,000 mL of 10 mM CsClO4 at room temperature. In parallel, the batches having the same soil/mineral compositions were run under the ambient air as controls. To prevent microbial activities, all batches were sterilized with 0.03% HCHO. To track geochemical changes, pH and electrical conductivity were monitored. Also, while solutions were regularly sampled and analyzed for trace metals as well as main cations and anions, solid phases were sampled to observe changes in mineralogical compositions. Geochemical changes in both solution and solid phases during the initial 6 month reaction will be presented. Acknowledgement: The "R&D Project on Environmental Management of Geologic CO2 Storage" from the KEITI (Project Number: 2014001810003).

Disproportionation of a crystalline citrate salt of a developmental pharmaceutical compound: characterization of the kinetics using pH monitoring and online Raman spectroscopy plus quantitation of the crystalline free base form in binary physical mixtures using FT-Raman, XRPD and DSC.

PubMed

Skrdla, Peter J; Zhang, Dan

2014-03-01

The crystalline citrate salt (CS) of a developmental pharmaceutical compound, MK-Q, was investigated in this work from two different, but related, perspectives. In the first part of the paper, the apparent disproportionation kinetics were surveyed using two different slurry systems, one containing water and the other a pH 6.9 phosphate buffer, using time-dependent measurements of the solution pH or by acquiring online Raman spectra of the solids. While the CS is generally stable when stored as a solid under ambient conditions of temperature and humidity, its low pHmax (<3) facilitates rapid disproportionation in aqueous solution, particularly at higher pH values. The rate of disappearance of the CS was found to obey first-order (Noyes-Whitney/dissolution rate-limited) kinetics, however, the formation of the crystalline product form in the slurry system was observed to exhibit kinetics consistent with a heterogeneous nucleation-and-growth mechanism. In the second part of this paper, more sensitive offline measurements made using XRPD, DSC and FT-Raman spectroscopy were applied to the characterization of binary physical mixtures of the CS and free base (FB) crystalline forms of MK-Q to obtain a calibration curve for each technique. It was found that all calibration plots exhibited good linearity of response, with the limit of detection (LOD) for each technique estimated to be ≤7 wt% FB. While additional calibration curves would need to be constructed to allow for accurate quantitation in various slurry systems, the general feasibility of these techniques is demonstrated for detecting low levels of CS disproportionation. Copyright © 2013 Elsevier B.V. All rights reserved.

Novel silica surface charge density mediated control of the optical properties of embedded optically active materials and its application for fiber optic pH sensing at elevated temperatures.

PubMed

Wang, Congjun; Ohodnicki, Paul R; Su, Xin; Keller, Murphy; Brown, Thomas D; Baltrus, John P

2015-02-14

Silica and silica incorporated nanocomposite materials have been extensively studied for a wide range of applications. Here we demonstrate an intriguing optical effect of silica that, depending on the solution pH, amplifies or attenuates the optical absorption of a variety of embedded optically active materials with very distinct properties, such as plasmonic Au nanoparticles, non-plasmonic Pt nanoparticles, and the organic dye rhodamine B (not a pH indicator), coated on an optical fiber. Interestingly, the observed optical response to varying pH appears to follow the surface charge density of the silica matrix for all the three different optically active materials. To the best of our knowledge, this optical effect has not been previously reported and it appears universal in that it is likely that any optically active material can be incorporated into the silica matrix to respond to solution pH or surface charge density variations. A direct application of this effect is for optical pH sensing which has very attractive features that can enable minimally invasive, remote, real time and continuous distributed pH monitoring. Particularly, as demonstrated here, using highly stable metal nanoparticles embedded in an inorganic silica matrix can significantly improve the capability of pH sensing in extremely harsh environments which is of increasing importance for applications in unconventional oil and gas resource recovery, carbon sequestration, water quality monitoring, etc. Our approach opens a pathway towards possible future development of robust optical pH sensors for the most demanding environmental conditions. The newly discovered optical effect of silica also offers the potential for control of the optical properties of optically active materials for a range of other potential applications such as electrochromic devices.

Titration of Alanine Monitored by NMR Spectroscopy: A Biochemistry Laboratory Experiment

ERIC Educational Resources Information Center

Waller, Francis J.; And Others

1977-01-01

The experiment described here involves simultaneous monitoring of pH and NMR chemical shifts during an aqueous titration of alpha- and beta-alanine. This experiment is designed for use in an undergraduate biochemistry course. (MR)

Dissipation of the Proton Electrochemical Potential in Intact Chloroplasts (II. The pH Gradient Monitored by Cytochrome f Reduction Kinetics).

PubMed Central

Nishio, J. N.; Whitmarsh, J.

1993-01-01

The potency of various uncouplers for collapsing the light-induced pH gradient across thylakoid membranes in intact chloroplasts was investigated by time-resolved optical spectroscopy. The thylakoid transmembrane pH gradient ([delta]pH) was monitored indirectly by measuring the rate of cytochrome (Cyt) f reduction following a light flash of sufficient duration to create a sizable [delta]pH. The results show that the rate of Cyt f reduction is controlled in part by the internal pH of the thylakoid inner aqueous space. At pH values from 6.5 to 8.0, the Cyt f reduction rate was maximal, whereas at lower pH values from 6.5 to 5.5 the reduction rate decreased to 25% of the maximal rate. The ability of three uncouplers, nigericin, carbonylcyanide m-chlorophenylhydrazone, and gramicidin, to accelerate the rate of Cyt f reduction was determined for intact chloroplasts isolated from spinach (Spinacia oleracea). The efficacy of the uncouplers for collapsing the [delta]pH was determined using the empirical relationship between the [delta]pH and the Cyt f reduction rate. For intact chloroplasts, nigericin was the most effective uncoupler, followed by carbonylcyanide m-chlorophenylhydrazone, which interacted strongly with bovine serum albumin. Gramicidin D, even at high gramicidin:chlorophyll ratios, did not completely collapse the pH gradient, probably because it partitions in the envelope membranes and does not enter the intact chloroplast. PMID:12231669

Plasmonic gold nanostar for biomedical sensing

NASA Astrophysics Data System (ADS)

Liu, Yang; Yuan, Hsiangkuo; Fales, Andrew M.; Vo-Dinh, Tuan

2014-03-01

Cancer has become one of most significant death reasons and causes approximately 7.9 million human deaths worldwide each year. The challenge to detect cancer at an early stage makes cancer-related biomarkers sensing attract more and more research interest and efforts. Surface-enhanced Raman scattering (SERS) provides a promising method for various biomarkers (DNA, RNA, protein, et al.) detection due to its high sensitivity, specificity and capability for multiple analytes detection. Raman spectroscopy is a non-destructive photon-scattering technique, which provides molecule-specific information on molecular vibrational energy levels. SERS takes advantage of plasmonic effects and can enhance Raman signal up to 1015 at "hot spots". Due to its excellent sensitivity, SERS has been capable of achieving single-molecule detection limit. Local pH environment has been identified to be a potential biomarker for cancer diagnosis since solid cancer contains highly acidic environments. A near-infrared (NIR) SERS nanoprobe based on gold nanostars for pH sensing is developed for future cancer detection. Near-infrared (NIR) light is more suitable for in vivo applications because of its low attenuation rate and tissue auto fluorescence. SERS spectrum of pH reporter under various pH environments is monitored and used for pH sensing. Furthermore, density functional theory (DFT) calculation is performed to investigate Raman spectra changes with pH at the molecular level. The study demonstrates that SERS is a sensitive tool to monitor minor molecular structural changes due to local pH environment for cancer detection.

Evaluation of Gastric pH and Serum Gastrin Concentrations in Cats with Chronic Kidney Disease.

PubMed

Tolbert, M K; Olin, S; MacLane, S; Gould, E; Steiner, J M; Vaden, S; Price, J

2017-09-01

Chronic kidney disease (CKD) is a highly prevalent condition in cats. Advanced CKD is associated with hyporexia and vomiting, which typically are attributed to uremic toxins and gastric hyperacidity. However, gastric pH studies have not been performed in cats with CKD. To determine if cats with CKD have decreased gastric pH compared to age-matched, healthy cats. Based on previous work demonstrating an association of hypergastrinemia and CKD, we hypothesized that cats with CKD would have decreased gastric pH compared to healthy, age-matched control cats. 10 CKD cats; 9 healthy control cats. All cats with concurrent disease were excluded on the basis of history, physical examination, CBC, plasma biochemistry profile, urinalysis, urine culture, serum total thyroxine concentration, and serum symmetric dimethylarginine concentration (controls only) obtained within 24 hours of pH monitoring and assessment of serum gastrin concentrations. Serum for gastrin determination was collected, and 12-hour continuous gastric pH monitoring was performed in all cats. Serum gastrin concentration, mean pH, and percentage time that gastric pH was strongly acidic (pH <1 and <2) were compared between groups. No significant differences in serum gastrin concentrations were observed between groups (medians [range]: CKD, 18.7 ng/dL [<10-659.0]; healthy, 54.6 ng/dL [<10-98.0]; P-value = 0.713) or of any pH parameters including mean ± SD gastric pH (CKD, 1.8 ± 0.5; healthy, 1.6 ± 0.3; P-value = 0.23). These findings suggest that cats with CKD may not have gastric hyperacidity compared to healthy cats and, therefore, may not need acid suppression. Thus, further studies to determine if there is a benefit to acid suppression in cats with CKD are warranted. Copyright © 2017 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

Gastric reacidification with betaine HCl in healthy volunteers with rabeprazole-induced hypochlorhydria.

PubMed

Yago, Marc R; Frymoyer, Adam R; Smelick, Gillian S; Frassetto, Lynda A; Budha, Nageshwar R; Dresser, Mark J; Ware, Joseph A; Benet, Leslie Z

2013-11-04

Previous studies have demonstrated that increased gastric pH from the use of acid-reducing agents, such as proton-pump inhibitors or H2-receptor antagonists, can significantly impact the absorption of weakly basic drugs that exhibit pH-dependent solubility. Clinically practical strategies to mitigate this interaction have not been developed. This pilot study evaluated the extent and time course of gastric reacidification after a solid oral dosage form of anhydrous betaine HCl in healthy volunteers with pharmacologically induced hypochlorhydria. Six healthy volunteers with baseline normochlorhydria (fasting gastric pH < 4) were enrolled in this single period study. Hypochlorhydria was induced via 20 mg oral rabeprazole twice daily for four days. On the fifth day, an additional 20 mg dose of oral rabeprazole was given and gastric pH was monitored continuously using the Heidelberg pH capsule. After gastric pH > 4 was confirmed for 15 min, 1500 mg of betaine HCl was given orally with 90 mL of water and gastric pH was continuously monitored for 2 h. Betaine HCl significantly lowered gastric pH by 4.5 (± 0.5) units from 5.2 (± 0.5) to 0.6 (± 0.2) (P < 0.001) during the 30 min interval after administration. The onset of effect of betaine HCl was rapid, with a mean time to pH < 3 of 6.3 (± 4.3) min. The reacidification period was temporary with a gastric pH < 3 and < 4 lasting 73 (± 33) and 77 (± 30) min, respectively. Betaine HCl was well tolerated by all subjects. In healthy volunteers with pharmacologically induced hypochlorhydria, betaine HCl was effective at temporarily lowering gastric pH. The rapid onset and relatively short duration of gastric pH reduction gives betaine HCl the potential to aid the absorption of orally administered weakly basic drugs that exhibit pH-dependent solubility when administered under hypochlorhydric conditions.

Gastric Re-acidification with Betaine HCl in Healthy Volunteers with Rabeprazole-Induced Hypochlorhydria

PubMed Central

Yago, Marc Anthony R.; Frymoyer, Adam R.; Smelick, Gillian S.; Frassetto, Lynda A.; Budha, Nageshwar R.; Dresser, Mark J.; Ware, Joseph A.; Benet, Leslie Z.

2013-01-01

Previous studies have demonstrated that increased gastric pH from the use of acid-reducing agents, such as proton-pump inhibitors or H2-receptor antagonists, can significantly impact the absorption of weakly basic drugs that exhibit pH-dependent solubility. Clinically practical strategies to mitigate this interaction have not been developed. This pilot study evaluated the extent and time course of gastric re-acidification after a solid oral dosage form of anhydrous betaine HCl in healthy volunteers with pharmacologically-induced hypochlorhydria. Six healthy volunteers with baseline normochlorhydria (fasting gastric pH < 4) were enrolled in this single period study. Hypochlorhydria was induced via 20 mg oral rabeprazole twice daily for four days. On the fifth day, an additional 20 mg dose of oral rabeprazole was given and gastric pH was monitored continuously using the Heidelberg pH capsule. After gastric pH > 4 was confirmed for 15 minutes, 1500 mg of betaine HCl was given orally with 90 mL of water and gastric pH was continuously monitored for 2 hours. Betaine HCl significantly lowered gastric pH by 4.5 (±0.5) units from 5.2 (±0.5) to 0.6 (±0.2) (P <0.001) during the 30 minute interval after administration. The onset of effect of betaine HCl was rapid, with a mean time to pH < 3 of 6.3 (±4.3) minutes. The re-acidification period was temporary with a gastric pH < 3 and < 4 lasting 73 (±33) and 77 (±30) minutes, respectively. Betaine HCl was well tolerated by all subjects. In healthy volunteers with pharmacologically-induced hypochlorhydria, betaine HCl was effective at temporarily lowering gastric pH. The rapid onset and relatively short duration of gastric pH reduction gives betaine HCl the potential to aid the absorption of orally administered weakly basic drugs that exhibit pH-dependent solubility when administered under hypochlorhydric conditions. PMID:23980906

Can terraced pond wetland systems improve urban watershed water quality?

NASA Astrophysics Data System (ADS)

Li, S.; Ho, M.; Flanagan, N. E.; Richardson, C. J.

2017-12-01

Properly built constructed wetlands are a more economic and efficient way of wastewater treatment compared with traditional methods, although their mechanisms are far from completely understood. As part of the Stream and Wetland Assessment Management Park (SWAMP), which is aimed to improve the water quality of downstream and thereby enhance watershed ecosystem services, a terraced three-pond wetland system was created near Duke University in 2014. This project is expected to promote the retention and settling of pollutants and sediment before runoffs enter downstream flow. The goal of this study is to examine: (1) whether a terraced pond wetland system improves water quality, during both baseline (low flow) and storm events (high flow), which increases pollutant inputs; and (2) how this system functions to remove pollutants, namely what components of this system (plant, soil or water) increase or decrease the level of pollutants. By analyzing a dataset consisting of more than four-year monthly samplings from Pond 1 (first pond in the system) and Pond 3 (last pond in the system), we found that the pond system has reduced total suspended solids (TSS) but only when elevated inputs occur. Dissolved oxygen (DO) is closely related to temperature and macrophytes growth; whereas acidity (pH), total nitrogen (TN), and total phosphorus (TP) did not show retention in the early stages of the system development. This system reaches its optimum for reducing TSS at the second pond, but the third pond has important effects on DO, pH, TN and TP. A monitoring in 2017 shows this pond system significantly reduces TSS while increasing dissolved oxygen and neutralizing pH after a storm event; although greater variations incurred within the system as time progresses after storm, overall retention function remained valid. Retention of the pollutants is primarily accomplished by the settling process, which occurs in stilled waterbody of the ponds and by the filtration of macrophytes. We expect more quantitative soil/plant uptake relations to be explored as the system ages.

Fluorescent probes and bioimaging: alkali metals, alkaline earth metals and pH.

PubMed

Yin, Jun; Hu, Ying; Yoon, Juyoung

2015-07-21

All living species and life forms have an absolute requirement for bio-functional metals and acid-base equilibrium chemistry owing to the critical roles they play in biological processes. Hence, a great need exists for efficient methods to detect and monitor biometals and acids. In the last few years, great attention has been paid to the development of organic molecule based fluorescent chemosensors. The availability of new synthetic fluorescent probes has made fluorescence microscopy an indispensable tool for tracing biologically important molecules and in the area of clinical diagnostics. This review highlights the recent advances that have been made in the design and bioimaging applications of fluorescent probes for alkali metals and alkaline earth metal cations, including lithium, sodium and potassium, magnesium and calcium, and for pH determination within biological systems.

Polyaniline deposition on tilted fiber Bragg grating for pH sensing

NASA Astrophysics Data System (ADS)

Lopez Aldaba, A.; González-Vila, Á.; Debliquy, M.; Lopez-Amo, M.; Caucheteur, C.; Lahem, D.

2017-04-01

In this paper, we present the results of a new pH sensor based on a polyaniline (PAni) coating on the surface of a tilted fiber Bragg grating. The pH-sensitive PAni was deposited by in situ chemical oxidative polymerization. The performance of the fabricated pH sensor was tested and the obtained pH values were compared with the results obtained using a pH meter device. It was found that the sensor exhibits response to pH changes in the range of 2-12, achieving a sensitivity of 46 pm/pH with a maximum error due to the hysteresis effect of +/-1.14 pH. The main advantages of this PAni-TFBG pH sensor are biochemical compatibility, temperature independence, long-term stability and remote realtime multipoint sensing features. This type of sensor could be used for biochemical applications, pipeline corrosion monitoring or remote-multipoint measurements.

Intra-domain phage display (ID-PhD) of peptides and protein mini-domains censored from canonical pIII phage display.

PubMed

Tjhung, Katrina F; Deiss, Frédérique; Tran, Jessica; Chou, Ying; Derda, Ratmir

2015-01-01

In this paper, we describe multivalent display of peptide and protein sequences typically censored from traditional N-terminal display on protein pIII of filamentous bacteriophage M13. Using site-directed mutagenesis of commercially available M13KE phage cloning vector, we introduced sites that permit efficient cloning using restriction enzymes between domains N1 and N2 of the pIII protein. As infectivity of phage is directly linked to the integrity of the connection between N1 and N2 domains, intra-domain phage display (ID-PhD) allows for simple quality control of the display and the natural variations in the displayed sequences. Additionally, direct linkage to phage propagation allows efficient monitoring of sequence cleavage, providing a convenient system for selection and evolution of protease-susceptible or protease-resistant sequences. As an example of the benefits of such an ID-PhD system, we displayed a negatively charged FLAG sequence, which is known to be post-translationally excised from pIII when displayed on the N-terminus, as well as positively charged sequences which suppress production of phage when displayed on the N-terminus. ID-PhD of FLAG exhibited sub-nanomolar apparent Kd suggesting multivalent nature of the display. A TEV-protease recognition sequence (TEVrs) co-expressed in tandem with FLAG, allowed us to demonstrate that 99.9997% of the phage displayed the FLAG-TEVrs tandem and can be recognized and cleaved by TEV-protease. The residual 0.0003% consisted of phage clones that have excised the insert from their genome. ID-PhD is also amenable to display of protein mini-domains, such as the 33-residue minimized Z-domain of protein A. We show that it is thus possible to use ID-PhD for multivalent display and selection of mini-domain proteins (Affibodies, scFv, etc.).

Effects of perilymphatic pressure, sodium nitroprusside, and bupivacaine on cochlear fluid pH of guinea pigs.

PubMed

Suzuki, Masaaki; Kotani, Ryosuke

2015-01-01

Hydrostatic positive pressure and vasoconstrictor acidified the cochlear fluids, whereas the vasodilator made the fluids alkaline. CBF might play a role in regulating cochlea fluid pH. Cochlea fluid pH is highly dependent on the HCO3(-)/CO2 buffer system. Cochlear blood flow (CBF) supplies O2 and removes CO2. It is speculated that cochlear blood flow changes might affect the balance of the HCO3(-)/CO2 buffer system in the cochlea. It is known that the elevation of inner ear pressure decreases the CBF, and local application of vasodilating or vasoconstricting agents directly to the cochlea changes the CBF. The purpose of this study was to elucidate the effect of positive hydrostatic inner ear pressure and application of a vasodilator and vasoconstrictor of cochlear vessels on the pH of the endolymph and perilymph. The authors performed animal physiological experiments on 30 guinea pigs. Hydrostatic positive pressure was infused through a glass capillary tube inserted into the scala tympani of the basal turn. The vasodilator, nitric oxide donor (sodium nitroprusside; SNP), and the vasoconstrictor, bupivacaine, were placed topically onto the round window of the guinea pig cochlea. Endolymph pH (pHe) and endocochlear potential (EP) were monitored by double-barreled ion-selective microelectrodes in the second turn of the guinea pig cochlea. During the topical application study, scala vestibuli perilymph pH (pHv) was also measured simultaneously in the second turn. The application of hydrostatic positive pressure caused a decrease in pHe and EP. Positive perilymphatic pressure caused the endolymph to become acidic pressure-dependently. Application of 3.0% SNP evoked an increase in both the pHe and pHv, following by a gradual recovery to baseline levels. On the other hand, 0.5% bupivacaine caused a decrease in both the pHe and pHv. The EP during topical application showed slight, non-significant changes.

Field demonstration of CO2 leakage detection in potable aquifers with a pulselike CO2-release test.

PubMed

Yang, Changbing; Hovorka, Susan D; Delgado-Alonso, Jesus; Mickler, Patrick J; Treviño, Ramón H; Phillips, Straun

2014-12-02

This study presents two field pulselike CO2-release tests to demonstrate CO2 leakage detection in a shallow aquifer by monitoring groundwater pH, alkalinity, and dissolved inorganic carbon (DIC) using the periodic groundwater sampling method and a fiber-optic CO2 sensor for real-time in situ monitoring of dissolved CO2 in groundwater. Measurements of groundwater pH, alkalinity, DIC, and dissolved CO2 clearly deviated from their background values, showing responses to CO2 leakage. Dissolved CO2 observed in the tests was highly sensitive in comparison to groundwater pH, DIC, and alkalinity. Comparison of the pulselike CO2-release tests to other field tests suggests that pulselike CO2-release tests can provide reliable assessment of geochemical parameters indicative of CO2 leakage. Measurements by the fiber-optic CO2 sensor, showing obvious leakage signals, demonstrated the potential of real-time in situ monitoring of dissolved CO2 for leakage detection at a geologic carbon sequestration (GCS) site. Results of a two-dimensional reactive transport model reproduced the geochemical measurements and confirmed that the decrease in groundwater pH and the increases in DIC and dissolved CO2 observed in the pulselike CO2-release tests were caused by dissolution of CO2 whereas alkalinity was likely affected by carbonate dissolution.

Assessment of Water-Quality Monitoring and a Proposed Water-Quality Monitoring Network for the Mosquito Lagoon Basin, East-Central Florida

USGS Publications Warehouse

Kroening, Sharon E.

2008-01-01

Surface- and ground-water quality data from the Mosquito Lagoon Basin were compiled and analyzed to: (1) describe historical and current monitoring in the basin, (2) summarize surface- and ground-water quality conditions with an emphasis on identifying areas that require additional monitoring, and (3) develop a water-quality monitoring network to meet the goals of Canaveral National Seashore (a National Park) and to fill gaps in current monitoring. Water-quality data were compiled from the U.S. Environmental Protection Agency's STORET system, the U.S. Geological Survey's National Water Information System, or from the agency which collected the data. Most water-quality monitoring focused on assessing conditions in Mosquito Lagoon. Significant spatial and/or seasonal variations in water-quality constituents in the lagoon were quantified for pH values, fecal coliform bacteria counts, and concentrations of dissolved oxygen, total nitrogen, total phosphorus, chlorophyll-a, and total suspended solids. Trace element, pesticide, and ground-water-quality data were more limited. Organochlorine insecticides were the major class of pesticides analyzed. A surface- and ground-water-quality monitoring network was designed for the Mosquito Lagoon Basin which emphasizes: (1) analysis of compounds indicative of human activities, including pesticides and other trace organic compounds present in domestic and industrial waste; (2) greater data collection in the southern part of Mosquito Lagoon where spatial variations in water-quality constituents were quantified; and (3) additional ground-water-quality data collection in the surficial aquifer system and Upper Floridan aquifer. Surface-water-quality data collected as part of this network would include a fixed-station monitoring network of eight sites in the southern part of the basin, including a canal draining Oak Hill. Ground-water quality monitoring should be done routinely at about 20 wells in the surficial aquifer system and Upper Floridan aquifer, distributed between developed and undeveloped parts of the basin. Water samples collected should be analyzed for a wide range of constituents, including physical properties, nutrients, suspended sediment, and constituents associated with increased urban development such as pesticides, other trace organic compounds associated with domestic and industrial waste, and trace elements.

Matrix metalloproteinase triggered size-shrinkable gelatin-gold fabricated nanoparticles for tumor microenvironment sensitive penetration and diagnosis of glioma

NASA Astrophysics Data System (ADS)

Ruan, Shaobo; He, Qin; Gao, Huile

2015-05-01

To improve glioma targeting delivery efficiency and to monitor drug delivery and treatment outcome, a novel tumor microenvironment sensitive size-shrinkable theranostic system was constructed and evaluated. The G-AuNPs-DC-RRGD system was constructed by fabricating small sized gold nanoparticles (AuNPs) onto matrix metalloproteinase-2 (MMP-2) degradable gelatin nanoparticles (GNPs), doxorubicin (DOX) and Cy5.5 were decorated onto AuNPs through a hydrazone bond to enable the system with pH triggered cargoes release, and RRGD, a tandem peptide of RGD and octarginine was surface-modified onto the system to enable it with glioma active targeting ability. In vitro, the size of G-AuNPs-DC-RRGD could effectively shrink from 188.2 nm to 55.9 nm after incubation with MMP-2, while DOX and Cy5.5 were released in a pH dependent manner. Cellular uptake demonstrated that G-AuNPs-DC-RRGD could be effectively taken up by cells with higher intensity than G-AuNPs-DC-PEG. A study of tumor spheroids further demonstrated that the particles with smaller size showed better penetration ability, while RRGD modification could further improve permeability. In vivo, G-AuNPs-DC-RRGD displayed the best glioma targeting and accumulation efficiency, with good colocalization with neovessels. Cy5.5 also was colocalized well with DOX, indicating that Cy5.5 could be used for imaging of DOX delivery.To improve glioma targeting delivery efficiency and to monitor drug delivery and treatment outcome, a novel tumor microenvironment sensitive size-shrinkable theranostic system was constructed and evaluated. The G-AuNPs-DC-RRGD system was constructed by fabricating small sized gold nanoparticles (AuNPs) onto matrix metalloproteinase-2 (MMP-2) degradable gelatin nanoparticles (GNPs), doxorubicin (DOX) and Cy5.5 were decorated onto AuNPs through a hydrazone bond to enable the system with pH triggered cargoes release, and RRGD, a tandem peptide of RGD and octarginine was surface-modified onto the system to enable it with glioma active targeting ability. In vitro, the size of G-AuNPs-DC-RRGD could effectively shrink from 188.2 nm to 55.9 nm after incubation with MMP-2, while DOX and Cy5.5 were released in a pH dependent manner. Cellular uptake demonstrated that G-AuNPs-DC-RRGD could be effectively taken up by cells with higher intensity than G-AuNPs-DC-PEG. A study of tumor spheroids further demonstrated that the particles with smaller size showed better penetration ability, while RRGD modification could further improve permeability. In vivo, G-AuNPs-DC-RRGD displayed the best glioma targeting and accumulation efficiency, with good colocalization with neovessels. Cy5.5 also was colocalized well with DOX, indicating that Cy5.5 could be used for imaging of DOX delivery. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01408e

[Evaluation of an automated pH-monitor and its logic of calculation].

PubMed

Ducrotté, P; Hubin, M; Xin, H; Roussignol, C; Denis, P

1990-01-01

The aim of this study was to compare the results of 3-hour postprandial esophageal pH recordings obtained simultaneously from a standard Beckmann pH recorder and a commercially available fully automated pH recording device, "pH 60" in 30 subjects. Both apparatuses were connected to the same pH probe and to a unique chart recorder to obtain simultaneous pH graphic tracings. The percentage of time between each pH level below pH 5, the percentage of time with pH less than 4 and Kaye's score were determined hourly and for the overall recording time. The pH graphic traces in both apparatuses were strictly identical demonstrating the accuracy of the analog-to-digital converter and the memory module to record pH changes. Moreover, we found a significant correlation (p less than 0.01) and a good overall agreement for all compared parameters between manual and computerized analysis. This study documents that the commercially available ambulatory esophageal pH instrument studied produces accurate data for the diagnosis of gastroesophageal reflux.

m-Cresol purple functionalized surface enhanced Raman scattering paper chips for highly sensitive detection of pH in the neutral pH range.

PubMed

Zou, Xinxin; Wang, Yunqing; Liu, Wanhui; Chen, Lingxin

2017-06-26

Herein, a pH sensitive paper SERS chip was prepared by selecting m-cresol purple, a molecule with halochromic properties in the neutral pH range as a Raman reporter. The adsorbed m-cresol purple underwent a reversible change in its electronic configuration from a non-resonant species to a resonant species, which resulted in a significant Raman signal intensity variation due to the transformation of the sensing mode from SERS to surface-enhanced resonance Raman scattering (SERRS). The chips have a sensitive pH range of 6.0 to 8.0 and exhibited good performance for the detection of natural water samples with detection precision of approximately 0.03 pH units, suggesting great potential for environmental pH monitoring applications.

Second-harmonic generation and theoretical studies of protonation at the water/α-TiO 2 (1 1 0) interface

NASA Astrophysics Data System (ADS)

Fitts, Jeffrey P.; Machesky, Michael L.; Wesolowski, David J.; Shang, Xiaoming; Kubicki, James D.; Flynn, George W.; Heinz, Tony F.; Eisenthal, Kenneth B.

2005-08-01

The pH of zero net surface charge (pH pzc) of the α-TiO 2 (1 1 0) surface was characterized using second-harmonic generation (SHG) spectroscopy. The SHG response was monitored during a series of pH titrations conducted at three NaNO 3 concentrations. The measured pH pzc is compared with a pH pzc value calculated using the revised MUltiSIte Complexation (MUSIC) model of surface oxygen protonation. MUSIC model input parameters were independently derived from ab initio calculations of relaxed surface bond lengths for a hydrated surface. Model (pH pzc 4.76) and experiment (pH pzc 4.8 ± 0.3) agreement establishes the incorporation of independently derived structural parameters into predictive models of oxide surface reactivity.

Photo-Fenton and modified photo-Fenton at neutral pH for the treatment of emerging contaminants in wastewater treatment plant effluents: a comparison.

PubMed

Klamerth, N; Malato, S; Agüera, A; Fernández-Alba, A

2013-02-01

This study compares two different solar photo-Fenton processes, conventional photo-Fenton at pH3 and modified photo-Fenton at neutral pH with minimal Fe (5 mg L⁻¹) and minimal initial H₂O₂ (50 mg L⁻¹) concentrations for the degradation of emerging contaminants in Municipal Wastewater Treatment Plants effluents in solar pilot plant. As Fe precipitates at neutral pH, complexing agents which are able to form photoactive species, do not pollute the environment or increase toxicity have to be used to keep the iron in solution. This study was done using real effluents containing over 60 different contaminants, which were monitored during treatment by liquid chromatography coupled to a hybrid quadrupole/linear ion trap mass analyzer (LC-QTRAP-MS/MS) operating in selected reaction monitoring (SRM) mode. Concentrations of the selected contaminants ranged from a few ng L⁻¹ to tens of μg L⁻¹. It was demonstrated in all cases the removal of over 95% of the contaminants. Photo-Fenton at pH3 provided the best treatment time, but has the disadvantage that the water must be previously acidified. The most promising process was photo-Fenton modified with Ethylenediamine-N,N'-disuccinic acid (EDDS), as the pH remained in the neutral range. Copyright © 2012 Elsevier Ltd. All rights reserved.

Development of Low-Toxicity Wastewater Stabilization for Spacecraft Water Recovery Systems

NASA Technical Reports Server (NTRS)

Mitchell, Julie L.; Adam, Niklas; Pickering, Karen D.; Alvarez, Giraldo N.

2015-01-01

Wastewater stabilization was an essential component of the spacecraft water cycle. The purpose of stabilizing wastewater was two-fold. First, stabilization prevents the breakdown of urea into ammonia, a toxic gas at high concentrations. Second, it prevents the growth of microorganisms, thereby mitigating hardware and water quality issues due to due biofilm and planktonic growth. Current stabilization techniques involve oxidizers and strong acids (pH=2) such as chromic and sulfuric acid, which are highly toxic and pose a risk to crew health. The purpose of this effort was to explore less toxic stabilization techniques, such as food-grade and commercial care preservatives. Additionally, certain preservatives were tested in the presence of a low-toxicity organic acid. Triplicate 300-milliliter volumes of urine were dosed with a predetermined quantity of stabilizer and stored for two weeks. During that time, pH, total organic carbon (TOC), ammonia, and turbidity were monitored. Those preservatives that showed the lowest visible microbial growth and stable pH were further tested in a six-month stability study. The results of the six-month study are also included in this paper.

Development of Low-Toxicity Urine Stabilization for Spacecraft Water Recovery Systems

NASA Technical Reports Server (NTRS)

Adam, Niklas; Mitchell, Julie L.; Pickering, Karen D.

2012-01-01

Wastewater stabilization is an essential component of the spacecraft water cycle. The purpose of stabilizing wastewater is two-fold. First, stabilization prevents the breakdown of urea into ammonia, a toxic gas at high concentrations. Second, it prevents the growth of microorganisms, thereby mitigating hardware and water quality issues due to due biofilm and planktonic growth. Current stabilization techniques involve oxidizers and strong acids (pH=2) such as chromic and sulfuric acid, which are highly toxic and pose a risk to crew health. The purpose of this effort is to explore less toxic stabilization techniques, such as food-grade and commercial care preservatives. Additionally, certain preservatives were tested in the presence of a low-toxicity organic acid. Triplicate 300-mL volumes of urine were dosed with a predetermined quantity of stabilizer and stored for two weeks. During that time, pH, total organic carbon (TOC), ammonia, and turbidity were monitored. Those preservatives that showed the lowest visible microbial growth and stable pH were further tested in a six-month stability study. The results of the six-month study are also included in this paper.

Development of Low-Toxicity Wastewater Stabilization for Spacecraft Water Recovery Systems

NASA Technical Reports Server (NTRS)

Adam, Niklas; Mitchell, Julie; Pickering, Karen; Carrier, Chris; Vega, Letty; Muirhead, Dean

2014-01-01

Wastewater stabilization was an essential component of the spacecraft water cycle. The purpose of stabilizing wastewater was two-fold. First, stabilization prevents the breakdown of urea into ammonia, a toxic gas at high concentrations. Second, it prevents the growth of microorganisms, thereby mitigating hardware and water quality issues due to due biofilm and planktonic growth. Current stabilization techniques involve oxidizers and strong acids (pH=2) such as chromic and sulfuric acid, which are highly toxic and pose a risk to crew health. The purpose of this effort was to explore less toxic stabilization techniques, such as food-grade and commercial care preservatives. Additionally, certain preservatives were tested in the presence of a low-toxicity organic acid. Triplicate 300-mL volumes of urine were dosed with a predetermined quantity of stabilizer and stored for two weeks. During that time, pH, total organic carbon (TOC), ammonia, and turbidity were monitored. Those preservatives that showed the lowest visible microbial growth and stable pH were further tested in a six-month stability study. The results of the six-month study are also included in this paper.

Micro CSI: A Microbial Citizen Science Initiative in Urban Watersheds

EPA Science Inventory

Across the Nation, a number of citizen science efforts have been conducted to monitor water quality. Efforts have included monitoring of bacteriological parameters (E. coli, enterococci, and fecal coliforms) and/or physicochemical parameters (temperature, turbidity, pH, conducti...

USE OF SONOCHEMISTRY IN MONITORING CHLORINATED HYDROCARBONS IN WATER

EPA Science Inventory

The U.S. Environmental Protection Agency (EPA) has been examining the potential of combining sonication with available measurement technologies for monitoring chlorinated hydrocarbons in water. The chloride ion (C1-) concentration, conductivity, and pH were measured before and af...

Ab initio determination of effective electron-phonon coupling factor in copper

NASA Astrophysics Data System (ADS)

Ji, Pengfei; Zhang, Yuwen

2016-04-01

The electron temperature Te dependent electron density of states g (ε), Fermi-Dirac distribution f (ε), and electron-phonon spectral function α2 F (Ω) are computed as prerequisites before achieving effective electron-phonon coupling factor Ge-ph. The obtained Ge-ph is implemented into a molecular dynamics (MD) and two-temperature model (TTM) coupled simulation of femtosecond laser heating. By monitoring temperature evolutions of electron and lattice subsystems, the result utilizing Ge-ph from ab initio calculation shows a faster decrease of Te and increase of Tl than those using Ge-ph from phenomenological treatment. The approach of calculating Ge-ph and its implementation into MD-TTM simulation is applicable to other metals.

Recent Advances in Point-of-Access Water Quality Monitoring

NASA Astrophysics Data System (ADS)

Korostynska, O.; Arshak, K.; Velusamy, V.; Arshak, A.; Vaseashta, Ashok

Clean water is one of our most valuable natural resources. In addition to providing safe drinking water it assures functional ecosystems that support fisheries and recreation. Human population growth and its associated increased demands on water pose risks to maintaining acceptable water quality. It is vital to assess source waters and the aquatic systems that receive inputs from industrial waste and sewage treatment plants, storm water systems, and runoff from urban and agricultural lands. Rapid and confident assessments of aquatic resources form the basis for sound environmental management. Current methods engaged in tracing the presence of various bacteria in water employ bulky laboratory equipment and are time consuming. Thus, real-time water quality monitoring is essential for National and International Health and Safety. Environmental water monitoring includes measurements of physical characteristics (e.g. pH, temperature, conductivity), chemical parameters (e.g. oxygen, alkalinity, nitrogen and phosphorus compounds), and abundance of certain biological taxa. Monitoring could also include assays of biological activity such as alkaline phosphatase, tests for toxins such as microcystins and direct measurements of pollutants such as heavy metals or hydrocarbons. Real time detection can significantly reduce the level of damage and also the cost to remedy the problem. This paper presents overview of state-of-the-art methods and devices used for point-of-access water quality monitoring and suggest further developments in this area.

Effects of in situ CO2 enrichment on structural characteristics, photosynthesis, and growth of the Mediterranean seagrass Posidonia oceanica

NASA Astrophysics Data System (ADS)

Cox, T. Erin; Gazeau, Frédéric; Alliouane, Samir; Hendriks, Iris E.; Mahacek, Paul; Le Fur, Arnaud; Gattuso, Jean-Pierre

2016-04-01

Seagrass is expected to benefit from increased carbon availability under future ocean acidification. This hypothesis has been little tested by in situ manipulation. To test for ocean acidification effects on seagrass meadows under controlled CO2/pH conditions, we used a Free Ocean Carbon Dioxide Enrichment (FOCE) system which allows for the manipulation of pH as continuous offset from ambient. It was deployed in a Posidonia oceanica meadow at 11 m depth in the Northwestern Mediterranean Sea. It consisted of two benthic enclosures, an experimental and a control unit both 1.7 m3, and an additional reference plot in the ambient environment (2 m2) to account for structural artifacts. The meadow was monitored from April to November 2014. The pH of the experimental enclosure was lowered by 0.26 pH units for the second half of the 8-month study. The greatest magnitude of change in P. oceanica leaf biometrics, photosynthesis, and leaf growth accompanied seasonal changes recorded in the environment and values were similar between the two enclosures. Leaf thickness may change in response to lower pH but this requires further testing. Results are congruent with other short-term and natural studies that have investigated the response of P. oceanica over a wide range of pH. They suggest any benefit from ocean acidification, over the next century (at a pH of ˜ 7.7 on the total scale), on Posidonia physiology and growth may be minimal and difficult to detect without increased replication or longer experimental duration. The limited stimulation, which did not surpass any enclosure or seasonal effect, casts doubts on speculations that elevated CO2 would confer resistance to thermal stress and increase the buffering capacity of meadows.

Transfer of Oleic Acid between Albumin and Phospholipid Vesicles

NASA Astrophysics Data System (ADS)

Hamilton, James A.; Cistola, David P.

1986-01-01

The net transfer of oleic acid between egg phosphatidylcholine unilamellar vesicles and bovine serum albumin has been monitored by 13C NMR spectroscopy and 90% isotopically substituted [1-13C]oleic acid. The carboxyl chemical shifts of oleic acid bound to albumin were different from those for oleic acid in phospholipid vesicles. Therefore, in mixtures of donor particles (vesicles or albumin with oleic acid) and acceptor particles (fatty acid-free albumin or vesicles), the equilibrium distribution of oleic acid was determined from chemical shift and peak intensity data without separation of donor and acceptor particles. In a system containing equal masses of albumin and phospholipid and a stoichiometry of 4-5 mol of oleic acid per mol of albumin, the oleic acid distribution was pH dependent, with >= 80% of the oleic acid associated with albumin at pH 7.4; association was >= 90% at pH 8.0. Decreasing the pH below 7.4 markedly decreased the proportion of fatty acid bound to albumin; at pH 5.4, <= 10% of the oleic acid was bound to albumin and >90% was associated with vesicles. The distribution was reversible with pH and was independent of whether vesicles or albumin acted as a donor. These data suggest that pH may strongly influence the partitioning of fatty acid between cellular membranes and albumin. The 13C NMR method is also advantageous because it provides information about the structural environments of oleic acid bound to albumin or phospholipid, the ionization state of oleic acid in each environment, and the structural integrity of the vesicles. In addition, minimum and maximum limits for the exchange rates of oleic acid among different environments were obtained from the NMR data.

Low-temperature solution processing of palladium/palladium oxide films and their pH sensing performance.

PubMed

Qin, Yiheng; Alam, Arif U; Pan, Si; Howlader, Matiar M R; Ghosh, Raja; Selvaganapathy, P Ravi; Wu, Yiliang; Deen, M Jamal

2016-01-01

Highly sensitive, easy-to-fabricate, and low-cost pH sensors with small dimensions are required to monitor human bodily fluids, drinking water quality and chemical/biological processes. In this study, a low-temperature, solution-based process is developed to prepare palladium/palladium oxide (Pd/PdO) thin films for pH sensing. A precursor solution for Pd is spin coated onto pre-cleaned glass substrates and annealed at low temperature to generate Pd and PdO. The percentages of PdO at the surface and in the bulk of the electrodes are correlated to their sensing performance, which was studied by using the X-ray photoelectron spectroscope. Large amounts of PdO introduced by prolonged annealing improve the electrode's sensitivity and long-term stability. Atomic force microscopy study showed that the low-temperature annealing results in a smooth electrode surface, which contributes to a fast response. Nano-voids at the electrode surfaces were observed by scanning electron microscope, indicating a reason for the long-term degradation of the pH sensitivity. Using the optimized annealing parameters of 200°C for 48 h, a linear pH response with sensitivity of 64.71±0.56 mV/pH is obtained for pH between 2 and 12. These electrodes show a response time shorter than 18 s, hysteresis less than 8 mV and stability over 60 days. High reproducibility in the sensing performance is achieved. This low-temperature solution-processed sensing electrode shows the potential for the development of pH sensing systems on flexible substrates over a large area at low cost without using vacuum equipment. Copyright © 2015 Elsevier B.V. All rights reserved.

Rapid monitoring of intermediate states and mass balance of nitrogen during denitrification by means of cavity enhanced Raman multi-gas sensing.

PubMed

Keiner, Robert; Herrmann, Martina; Küsel, Kirsten; Popp, Jürgen; Frosch, Torsten

2015-03-15

The comprehensive investigation of changes in N cycling has been challenging so far due to difficulties with measuring gases such as N2 and N2O simultaneously. In this study we introduce cavity enhanced Raman gas spectroscopy as a new analytical methodology for tracing the stepwise reduction of (15)N-labelled nitrate by the denitrifying bacteria Pseudomonas stutzeri. The unique capabilities of Raman multi-gas analysis enabled real-time, continuous, and non-consumptive quantification of the relevant gases ((14)N2, (14)N2O, O2, and CO2) and to trace the fate of (15)N-labeled nitrate substrate ((15)N2, (15)N2O) added to a P. stutzeri culture with one single measurement. Using this new methodology, we could quantify the kinetics of the formation and degradation for all gaseous compounds (educts and products) and thus study the reaction orders. The gas quantification was complemented with the analysis of nitrate and nitrite concentrations for the online monitoring of the total nitrogen element budget. The simultaneous quantification of all gases also enabled the contactless and sterile online acquisition of the pH changes in the P. stutzeri culture by the stoichiometry of the redox reactions during denitrification and the CO2-bicarbonate equilibrium. Continuous pH monitoring - without the need to insert an electrode into solution - elucidated e.g. an increase in the slope of the pH value coinciding with an accumulation of nitrite, which in turn led to a temporary accumulation of N2O, due to an inhibition of nitrous oxide reductase. Cavity enhanced Raman gas spectroscopy has a high potential for the assessment of denitrification processes and can contribute substantially to our understanding of nitrogen cycling in both natural and agricultural systems. Copyright © 2015 Elsevier B.V. All rights reserved.

Physiological validation of photochemical reflectance index (PRI) as a photosynthetic parameter using Arabidopsis thaliana mutants.

PubMed

Kohzuma, Kaori; Hikosaka, Kouki

2018-03-25

Non-photochemical quenching (NPQ) is the most important photoprotective system in higher plants. NPQ can be divided into several steps according to the timescale of relaxation of chlorophyll fluorescence after reaching a steady state (i.e., the fast phase, qE; middle phase, qZ or qT; and slow phase, qI). The dissipation of excess energy as heat during the xanthophyll cycle, a large component of NPQ, is detectable during the fast to middle phase (sec to min). Although thermal dissipation is primarily investigated using indirect methods such as chlorophyll a fluorescence measurements, such analyses require dark adaptation or the application of a saturating pulse during measurement, making it difficult to continuously monitor this process. Here, we designed an unconventional technique for real-time monitoring of changes in thylakoid lumen pH (as reflected by changes in xanthophyll pigment content) based on the photochemical reflectance index (PRI), which we estimated by measuring light-driven leaf reflectance at 531 nm. We analyzed two Arabidopsis thaliana mutants, npq1 (unable to convert violaxanthin to zeaxanthin due to inhibited violaxanthin de-epoxidase [VDE] activity) and npq4 (lacking PsbS protein), to uncover the regulator of the PRI. The PRI was variable in wild-type and npq4 plants, but not in npq1, indicating that the PRI is related to xanthophyll cycle-dependent thermal energy quenching (qZ) rather than the linear electron transport rate or NPQ. In situ lumen pH substitution using a pH-controlled buffer solution caused a shift in PRI. These results suggest that the PRI reflects only xanthophyll cycle conversion and is therefore a useful parameter for monitoring thylakoid lumen pH (reflecting VDE activity) in vivo. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Is the Routine Use of Impedance Analysis for the Diagnosis of Gastro-Esophageal Reflux Disease More Expensive than Conventional pH Monitoring? Cost Analysis of Two Procedures.

PubMed

Törer, Nurkan; Aytaç, Özgür

2017-06-01

Conventional 24-h pH monitoring is the gold standard for the diagnosis of non-erosive, non-acidic gastro-esophageal reflux disease. Multichannel Intraluminal Impedance (MII) analysis markedly improves diagnostic accuracy of non-erosive, non-acidic gastro-esophageal reflux disease. However, MII catheters are more expensive than standard catheters. This study aimed to determine the rates of acid or non-acid reflux and by making a retrospective projection, to predict the costs of two algorithms. We retrospectively reviewed the medical data of 102 patients who presented to our hospital with suspected non-erosive GERD and underwent 24 h impedance/pH-monitoring. Demographic characteristics, Demeester scores, number of reflux episodes, and results of impedance analysis were recorded. According to these data, cost was calculated either for the scenario in which impedance measurement was performed solely or following a negative conventional pH monitoring. Thirty-seven of all 102 patients (36.3 %) had a Demeester score greater than 14.7. These patients were assigned as group 1 (acid reflux). The impedance analysis of the remaining 65 patients detected 34 patients (33.3 %) to have more than 50 reflux episodes over a period of 24 h and assigned as Group 2, and 31 patients (30.4 %) had no reflux (group 3). The cost of the single- step algorithm using MII catheter was calculated as $15,300, while the total cost of two-step scenario would have been predicted as $16,890. Our study showed that an initial conventional pH monitoring can make the diagnosis of GERD in only one third of the patients with suspected non-erosive GERD. In nearly two-thirds of patients, however, repeated procedures and use of impedance catheters are needed. It is clear that this algorithm has certain drawbacks with regard to cost, patient comfort, and workforce loss.

Simultaneous Determination of Oxygen and pH Inside Microfluidic Devices Using Core-Shell Nanosensors.

PubMed

Ehgartner, Josef; Strobl, Martin; Bolivar, Juan M; Rabl, Dominik; Rothbauer, Mario; Ertl, Peter; Borisov, Sergey M; Mayr, Torsten

2016-10-04

A powerful online analysis setup for the simultaneous detection of oxygen and pH is presented. It features core-shell nanosensors, which enable contactless and inexpensive read-out using adapted oxygen meters via modified dual lifetime referencing in the frequency domain (phase shift measurements). Lipophilic indicator dyes were incorporated into core-shell structured poly(styrene-block-vinylpyrrolidone) nanoparticles (average diameter = 180 nm) yielding oxygen nanosensors and pH nanosensors by applying different preparation protocols. The oxygen indicator platinum(II) meso-tetra(4-fluorophenyl) tetrabenzoporphyrin (PtTPTBPF) was entrapped into the polystyrene core (oxygen nanosensors) and a pH sensitive BF 2 -chelated tetraarylazadipyrromethene dye (aza-BODIPY) was incorporated into the polyvinylpyrrolidone shell (pH nanosensors). The brightness of the pH nanoparticles was increased by more than 3 times using a light harvesting system. The nanosensors have several advantages such as being excitable with red light, emitting in the near-infrared spectral region, showing a high stability in aqueous media even at high particle concentrations, high ionic strength, or high protein concentrations and are spectrally compatible with the used read-out device. The resolution for oxygen of the setup is 0.5-2.0 hPa (approximately 0.02-0.08 mg/L of dissolved oxygen) at low oxygen concentrations (<50 hPa) and 4-8 hPa (approximately 0.16-0.32 mg/L of dissolved oxygen) at ambient air oxygen concentrations (approximately 200 hPa at 980 mbar air pressure) at room temperature. The pH resolution is 0.03-0.1 pH units within the dynamic range (apparent pK a 7.23 ± 1.0) of the nanosensors. The sensors were used for online monitoring of pH changes during the enzymatic transformation of Penicillin G to 6-aminopenicillanic acid catalyzed by Penicillin G acylase in miniaturized stirred batch reactors or continuous flow microreactors.

A pH-responsive interface derived from resilin-mimetic protein Rec1-resilin.

PubMed

Truong, My Y; Dutta, Naba K; Choudhury, Namita R; Kim, Misook; Elvin, Christopher M; Hill, Anita J; Thierry, Benjamin; Vasilev, Krasimir

2010-05-01

In this investigation, for the first time we report the effects of pH on the molecular orientation, packing density, structural properties, adsorption characteristics and viscoelastic behaviour of resilin-mimetic protein rec1-resilin at the solid-liquid interface using quartz crystal microbalance with dissipation monitoring (QCM-D) and surface plasmon resonance (SPR) spectroscopy. QCM-D and SPR data confirm that the binding ability of rec1-resilin on a substrate is strongly pH-dependent the protein packing density on a gold surface is calculated to be 4.45 x 10(13) per cm(2) at the isoelectric point (IEP approximately 4.9), 8.79 x 10(11) per cm(2) at pH 2 and 9.90 x 10(11) per cm(2) at pH 12, respectively. Our findings based on the thickness, dissipation and viscoelasticity of the rec1-resilin adlayer also indicate that it is adsorbed onto the gold substrate with different orientation depending on pH, such as back-on adsorption at acidic pH of 2, compact end-on bilayer adsorption at the IEP and side-on at high alkaline pH of 12. When rec1-resilin is 'pinned' to the substrate at IEP and subsequently exposed to an electrolyte solution adjusted to different pH, it switches from a compact globular conformation of the bio-macromolecule at the IEP to a coil conformation at pH between IEP to IED (IED = pKa value of tyrosine amino acid residue) and an extended coil conformation at pH > IED. This transformation from globule to coil to extended coil conformation is kinetically fast, robust and completely reversible. Such responsive surfaces created using 'smart' biomimetic rec1-resilin have the potential to find applications in many areas including biotechnology, medicine, sensors, controlled drug delivery systems and engineering. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

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

PubMed

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.

Novel LC-ESI/MS/MSn Method for the Characterization and Quantification of 2′-Deoxyguanosine Adducts of the Dietary Carcinogen 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine by 2-D Linear Quadrupole Ion Trap Mass Spectrometry

PubMed Central

Goodenough, Angela K.; Schut, Herman A. J.; Turesky, Robert J.

2008-01-01

An accurate and sensitive liquid chromatography-electrospray ionization/multi-stage mass spectrometry (LC-ESI/MS/MSn) technique has been developed for the characterization and quantification of 2′-deoxyguanosine (dG) adducts of the dietary mutagen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). PhIP is an animal and potential human carcinogen that occurs in grilled meats. Following enzymatic digestion and adduct enrichment by solid-phase extraction (SPE), PhIP—DNA adducts were analyzed by MS/MS and MSn scan modes on a 2-D linear quadrupole ion trap mass spectrometer (QIT/MS). The major DNA adduct, N-(deoxyguanosin-8-yl)-2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (dG-C8-PhIP), was detected in calf thymus (CT) DNA modified in vitro with a bioactivated form of PhIP and in the colon and liver of rats given PhIP as part of the diet. The lower limit of detection (LOD) was 1 adduct per 108 DNA bases, and the limit of quantification (LOQ) was 3 adducts per 108 DNA bases in both MS/MS and MS3 scan modes, using 27 μg of DNA for analysis. Measurements were based on isotope dilution with the internal standard, N-(deoxyguanosin-8-yl)-2-amino-1-(trideutero)methyl-6-phenylimidazo[4,5-b]pyridine (dG-C8-[2H3C]-PhIP). The selected reaction monitoring (SRM) scan mode in MS/MS was employed to monitor the loss of deoxyribose (dR) from the protonated molecules of the adducts ([M + H - 116]+). The consecutive reaction monitoring (CRM) scan modes in MS3 and MS4 were used to measure and further characterize product ions of the aglycone ion (BH2+) (Guanyl-PhIP). The MS3 scan mode was effective in eliminating isobaric interferences observed in the MS/MS scan mode and resulted in an improved signal-to-noise (S/N) ratio. Moreover, the product ion spectra obtained by the MSn scan modes provided rich structural information about the adduct and were used to corroborate the identity of dG-C8-PhIP. In addition, an isomeric dG-PhIP adduct was detected in vivo. This LCESI/MS/MSn method is the first reported application on the use of the MS3 scan mode for the analysis of DNA adducts in vivo. PMID:17305409

Carboxylate-Containing Two-Photon Probe for the Simultaneous Detection of Extra- and Intracellular pH Values in Colon Cancer Tissue.

PubMed

Si, Ho Young; Cho, Myoung Ki; Kang, Ji Su; Noh, Choong-Kyun; Shin, Sung Jae; Lim, Chang Su; Kim, Hwan Myung

2018-06-11

Acidified extracellular pH (pHe) is directly related to various disorders such as tumor invasion and the resistance to drugs. In this study, we developed two-photon-excitable emission ratiometric probes (XBH1-3) for the in situ measurement of pHe. These probes, based on benzimidazole and polar solubilizing groups, exhibited a strong two-photon-induced fluorescence and sensitive blue-to-green emission color changes with p K a values of 5.1-5.7. XBH1, containing a carboxylic acid, stained the extracellular region in neutral media; it entered the cell under acidic media, thereby allowing a precise measurement of the extra- and intra-cellular pH values in the acidified tissue. XBH2, containing the sulfonate peripheral unit, facilitated the monitoring of the pHe value only. Ratiometric two-photon microscopy imaging revealed that XBH1 can directly monitor the pH values both inside and outside the cells in colon cancer tissue; there is also the morphological aspect. This could be useful for cancer analyses and drug development.

Ion leaching and soil solution acidification in a vadose zone under soil treated with sewage sludge for agriculture.

PubMed

Borba, Ricardo Perobelli; Ribeirinho, Victor Sanches; de Camargo, Otávio Antonio; de Andrade, Cristiano Alberto; Kira, Carmen Silvia; Coscione, Aline Reneé

2018-02-01

In this study, we performed monitoring of the soil solution (SS) over 10 years on a loamy/clayey-textured Dark Red Dystroferric Oxisol that received sewage sludge for agricultural purposes. The SS was obtained by lysimeters installed along the walls of a well at 1 m, 2 m, 3 m, 4 m and 5 m in depth. The major ions found in the SS were NO 3 - , SO 4 2- , Cl - , Ca 2+ , Mg 2+ , Al 3+ , Pb 2+ , Cd 2+ and Zn 2+ , and the pH level ranged from 4 to 6.5 along the profile. Throughout the first three years of monitoring, the pH to a 3-m depth became more acidic, and in the last year, this trend reached 5 m. At the 5-m depth, the pH decreased from 6.5 to 4.5 from the first to the last monitoring. The SS acidification was provoked by both nitrite oxidation and ion leaching. The leaching of H + or the possible ion exchange/desorption of H + due to the leached cations (Ca 2+ and Mg 2+ ) at the 4-m and 5-m depth caused the pH decrease. The ionic strength (IS) of the solution controlled the ion leaching. The sludge application increased the IS to 3 m, increasing the density of the soil charges and its ability to absorb ions. After the sludge application was completed, there was a decrease in IS of the SS as well as a decrease in ion absorption and retention abilities, which promoted leaching to greater depths. During the entire monitoring process, NO 3 - , Cd and Pb remained above the potability limit. Copyright © 2017 Elsevier Ltd. All rights reserved.

The value of early wireless esophageal pH monitoring in diagnosing functional heartburn in refractory gastroesophageal reflux disease.

PubMed

Park, Eun-Young; Choi, Myung-Gyu; Baeg, Meonggi; Lim, Chul-Hyun; Kim, Jinsu; Cho, Yukyung; Park, Jaemyung; Lee, Inseok; Kim, Sangwoo; Choi, Kyuyong

2013-10-01

It is difficult to differentiate functional heartburn from proton pump inhibitor (PPI) failure. The aims of this study were to assess the role of early wireless esophageal pH monitoring in patients referred with gastroesophageal reflux disease (GERD) and to identify differences in the clinical spectrum among GERD subtypes. We enrolled consecutive referred patients with suspected GERD. After endoscopy on the first visit, all underwent wireless esophageal pH monitoring when off the PPI. Two hundred thirty patients were enrolled. These patients were classified into a reflux esophagitis group (20, 8.7 %) and a normal endoscopic findings group (210, 91.3 %). Among the 210 patients in the normal endoscopic findings group, 63 (27.4 %) were diagnosed with pathological reflux, 35 (15.2 %) with hypersensitive esophagus, 87 (37.8 %) with normal acid exposure with negative symptom association, and 25 (10.9 %) with test failure. These groups did not differ in age, body mass index, smoking habit, alcohol consumption, symptom severity, quality of life, presence of atypical symptoms, overlap with irritable bowel syndrome, and the frequency of somatization, depression, and anxiety. PPI responses were evaluated in 135 patients. Fifty patients (37.0 %) were not responsive to the 4-week treatment; 26 (19.3 %) were diagnosed with refractory non-erosive gastroesophageal disease, and 24 (17.8 %) with functional heartburn. The demographics and clinical and psychological characteristics did not differ between the two groups. Demographic characteristics and symptom patterns alone cannot differentiate functional heartburn from various subtypes of GERD. Wireless esophageal pH monitoring should be considered for the initial evaluation of GERD in the tertiary referral setting.

Colour and stability assessment of blue ferric anthocyanin chelates in liquid pectin-stabilised model systems.

PubMed

Buchweitz, M; Brauch, J; Carle, R; Kammerer, D R

2013-06-01

The formation of blue coloured ferric anthocyanin chelates and their colour stability during storage and thermal treatment were monitored in a pH range relevant to food (3.6-5.0). Liquid model systems were composed of different types of Citrus pectins, juices (J) and the respective phenolic extracts (E) from elderberry (EB), black currant (BC), red cabbage (RC) and purple carrot (PC) in the presence of ferric ions. For EB, BC and PC, pure blue colours devoid of a violet tint were exclusively observed for the phenolic extracts and at pH values ≥ 4.5 in model systems containing high methoxylated and amidated pectins, respectively. Colour and its stability strongly depended on the amount of ferric ions and the plant source; however, colour decay could generally be described as a pseudo-first-order kinetics. Despite optimal colour hues for RC-E and RC-J, storage and heat stabilities were poor. Highest colour intensities and best stabilities were observed for model systems containing PC-E at a molar anthocyanin:ferric ion ratio of 1:2. Ascorbic and lactic acids interfered with ferric ions, thus significantly affecting blue colour evolution and stability. Colour loss strongly depended on heat exposure with activation energies ranging between 60.5 and 78.4 kJ/mol. The comprehensive evaluation of the interrelationship of pigment source, pH conditions and pectin type on chelate formation and stability demonstrated that ferric anthocyanin chelates are promising natural blue food colourants. Copyright © 2012 Elsevier Ltd. All rights reserved.

Sensor Systems for Space Life Sciences

NASA Technical Reports Server (NTRS)

Somps, Chris J.; Hines, John W.; Connolly, John P. (Technical Monitor)

1995-01-01

Sensors 2000! (S2K!) is a NASA Ames Research Center engineering initiative designed to provide biosensor and bio-instrumentation systems technology expertise to NASA's life sciences spaceflight programs. S2K! covers the full spectrum of sensor technology applications, ranging from spaceflight hardware design and fabrication to advanced technology development, transfer and commercialization. S2K! is currently developing sensor systems for space biomedical applications on BION (a Russian biosatellite focused on Rhesus Monkey physiology) and NEUROLAB (a Space Shuttle flight devoted to neuroscience). It's Advanced Technology Development-Biosensors (ATD-B) project focuses efforts in five principle areas: biotelemetry Systems, chemical and biological sensors, physiological sensors, advanced instrumentation architectures, and data and information management. Technologies already developed and tested included, application-specific sensors, preamplifier hybrids, modular programmable signal conditioners, power conditioning and distribution systems, and a fully implantable dual channel biotelemeter. Systems currently under development include a portable receiver system compatible with an off-the-shelf analog biotelemeter, a 4 channel digital biotelemetry system which monitors pH, a multichannel, g-processor based PCM biotelemetry system, and hand-held personal monitoring systems. S2K! technology easily lends itself to telescience and telemedicine applications as a front-end measurement and data acquisition device, suitable for obtaining and configuring physiological information, and processing that information under control from a remote location.

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

PubMed

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.

Adsorption of Fe(II) and U(VI) to carboxyl-functionalized microspheres: The influence of speciation on uranyl reduction studied by titration and XAFS

NASA Astrophysics Data System (ADS)

Boyanov, Maxim I.; O'Loughlin, Edward J.; Roden, Eric E.; Fein, Jeremy B.; Kemner, Kenneth M.

2007-04-01

The chemical reduction of U(VI) by Fe(II) is a potentially important pathway for immobilization of uranium in subsurface environments. Although the presence of surfaces has been shown to catalyze the reaction between Fe(II) and U(VI) aqueous species, the mechanism(s) responsible for the enhanced reactivity remain ambiguous. To gain further insight into the U-Fe redox process at a complexing, non-conducting surface that is relevant to common organic phases in the environment, we studied suspensions containing combinations of 0.1 mM U(VI), 1.0 mM Fe(II), and 4.2 g/L carboxyl-functionalized polystyrene microspheres. Acid-base titrations were used to monitor protolytic reactions, and Fe K-edge and U L-edge X-ray absorption fine structure spectroscopy was used to determine the valence and atomic environment of the adsorbed Fe and U species. In the Fe + surface carboxyl system, a transition from monomeric to oligomeric Fe(II) surface species was observed between pH 7.5 and pH 8.4. In the U + surface carboxyl system, the U(VI) cation was adsorbed as a mononuclear uranyl-carboxyl complex at both pH 7.5 and 8.4. In the ternary U + Fe + surface carboxyl system, U(VI) was not reduced by the solvated or adsorbed Fe(II) at pH 7.5 over a 4-month period, whereas complete and rapid reduction to U(IV) nanoparticles occurred at pH 8.4. The U(IV) product reoxidized rapidly upon exposure to air, but it was stable over a 4-month period under anoxic conditions. Fe atoms were found in the local environment of the reduced U(IV) atoms at a distance of 3.56 Å. The U(IV)-Fe coordination is consistent with an inner-sphere electron transfer mechanism between the redox centers and involvement of Fe(II) atoms in both steps of the reduction from U(VI) to U(IV). The inability of Fe(II) to reduce U(VI) in solution and at pH 7.5 in the U + Fe + carboxyl system is explained by the formation of a transient, "dead-end" U(V)-Fe(III) complex that blocks the U(V) disproportionation pathway after the first electron transfer. The increased reactivity at pH 8.4 relative to pH 7.5 is explained by the reaction of U(VI) with an Fe(II) oligomer, whereby the bonds between Fe atoms facilitate the transfer of a second electron to the hypothetical U(V)-Fe(III) intermediate. We discuss how this mechanism may explain the commonly observed higher efficiency of uranyl reduction by adsorbed or structural Fe(II) relative to aqueous Fe(II).

Environmental Monitoring Instrumentation and Monitoring Techniques for Space Shuttle Launches.

DTIC Science & Technology

1983-07-01

Monitoring Instrumentation 32 1. Chemiluminescence HCl 32 2. Passive Dosimeter 34 3. Piezoelectric Quartz Crystal Microbalance 34 iJ ,- r, T , .{ , , : , Z...Sensing for STS Launohes 44 IV. SUISIAiR AND CONCLUSIONS 45 V. IBCOIMXIONS 47 References 49 Appendix A - Dosimeter Tube Monitoring Results 52 B - TenaxR...Monitoring Results 6 3 Summary of GBOMET HCI Data for the Launches of STS-i through 8 STS-5 at KSC 4 Dosimeter Tube Inlet Configuration Comparison 14 5 pH

Early development and molecular plasticity in the Mediterranean sea urchin Paracentrotus lividus exposed to CO2-driven acidification.

PubMed

Martin, Sophie; Richier, Sophie; Pedrotti, Maria-Luiza; Dupont, Sam; Castejon, Charlotte; Gerakis, Yannis; Kerros, Marie-Emmanuelle; Oberhänsli, François; Teyssié, Jean-Louis; Jeffree, Ross; Gattuso, Jean-Pierre

2011-04-15

Ocean acidification is predicted to have significant effects on benthic calcifying invertebrates, in particular on their early developmental stages. Echinoderm larvae could be particularly vulnerable to decreased pH, with major consequences for adult populations. The objective of this study was to understand how ocean acidification would affect the initial life stages of the sea urchin Paracentrotus lividus, a common species that is widely distributed in the Mediterranean Sea and the NE Atlantic. The effects of decreased pH (elevated P(CO(2))) were investigated through physiological and molecular analyses on both embryonic and larval stages. Eggs and larvae were reared in Mediterranean seawater at six pH levels, i.e. pH(T) 8.1, 7.9, 7.7, 7.5, 7.25 and 7.0. Fertilization success, survival, growth and calcification rates were monitored over a 3 day period. The expression of genes coding for key proteins involved in development and biomineralization was also monitored. Paracentrotus lividus appears to be extremely resistant to low pH, with no effect on fertilization success or larval survival. Larval growth was slowed when exposed to low pH but with no direct impact on relative larval morphology or calcification down to pH(T) 7.25. Consequently, at a given time, larvae exposed to low pH were present at a normal but delayed larval stage. More surprisingly, candidate genes involved in development and biomineralization were upregulated by factors of up to 26 at low pH. Our results revealed plasticity at the gene expression level that allows a normal, but delayed, development under low pH conditions.

Lower pH values of weakly acidic refluxes as determinants of heartburn perception in gastroesophageal reflux disease patients with normal esophageal acid exposure.

PubMed

de Bortoli, N; Martinucci, I; Savarino, E; Franchi, R; Bertani, L; Russo, S; Ceccarelli, L; Costa, F; Bellini, M; Blandizzi, C; Savarino, V; Marchi, S

2016-01-01

Multichannel impedance pH monitoring has shown that weakly acidic refluxes are able to generate heartburn. However, data on the role of different pH values, ranging between 4 and 7, in the generation of them are lacking. The aim of this study was to evaluate whether different pH values of weakly acidic refluxes play a differential role in provoking reflux symptoms in endoscopy-negative patients with physiological esophageal acid exposure time and positive symptom index and symptom association probability for weakly acidic refluxes. One hundred and forty-three consecutive patients with gastroesophageal reflux disease, nonresponders to proton pump inhibitors (PPIs), were allowed a washout from PPIs before undergoing: upper endoscopy, esophageal manometry, and multichannel impedance pH monitoring. In patients with both symptom index and symptom association probability positive for weakly acidic reflux, each weakly acidic reflux was evaluated considering exact pH value, extension, physical characteristics, and correlation with heartburn. Forty-five patients with normal acid exposure time and positive symptom association probability for weakly acidic reflux were identified. The number of refluxes not heartburn related was higher than those heartburn related. In all distal and proximal liquid refluxes, as well as in distal mixed refluxes, the mean pH value of reflux events associated with heartburn was significantly lower than that not associated. This condition was not confirmed for proximal mixed refluxes. Overall, a low pH of weakly acidic reflux represents a determinant factor in provoking heartburn. This observation contributes to better understand the pathophysiology of symptoms generated by weakly acidic refluxes, paving the way toward the search for different therapeutic approaches to this peculiar condition of esophageal hypersensitivity. © 2014 International Society for Diseases of the Esophagus.

Naked-eye point-of-care testing platform based on a pH-responsive superwetting surface: toward the non-invasive detection of glucose

NASA Astrophysics Data System (ADS)

Gao, Zhong Feng; Sann, Ei Ei; Lou, Xiaoding; Liu, Renyi; Dai, Jun; Zuo, Xiaolei; Xia, Fan; Jiang, Lei

2018-04-01

Herein, we demonstrate a contact angle (CA)-based naked-eye point-of-care testing platform with rapid pH-responsive superwettability that can switch between superhydrophilic and superhydrophobic properties for quantitative biosensing. The CA of the droplet on the pH-responsive surface approached 0° at pH 1 and conversely reached 161.4° ± 6.2° at pH 13. We realized the sensitive detection of the pH, urea, and glucose by monitoring the changes in the CA. The traditional invasive diagnosis of diabetes causes pain and brings the risk of infections, such as acquired immune deficiency syndrome (AIDS), hepatitis B, hepatitis C, and syphilis, to the user. To address this issue, we implemented a method for the non-invasive diagnosis of diabetes in human saliva and urine, which avoided the significant drawbacks mentioned above. The accuracy of this method was demonstrated by comparing the results with those from commercial glucometers and theoretical calculations. Interestingly, we successfully monitored glucose levels in sweat before, during, and after cycling. The sensing performance was barely influenced by the temperature, elevation, and droplet color, illustrating promise for expansion to hundreds of millions of potential customers, especially those with color blindness or color weakness. Given its low cost, lack of instruments, and rapid response (within 1 s), this strategy might overcome the limitations of the mechanical stability and durability of superwettable materials and thus might extend the industrial-scale application of bioinspired superwettable systems.

Patients with symptoms of delayed gastric emptying have a high prevalence of oesophageal dysmotility, irrespective of scintigraphic evidence of gastroparesis.

PubMed

Triadafilopoulos, George; Nguyen, Linda; Clarke, John O

2017-01-01

Patients with symptoms suggestive of gastroparesis exhibit several symptoms, such as epigastric pain, postprandial fullness, bloating and regurgitation. It is uncertain if such symptoms reflect underlying oesophageal motor disorder. To examine whether patients with epigastric pain and postprandial distress syndrome suggestive of functional dyspepsia and/or gastroparesis also have concomitant oesophageal motility abnormalities and, if so, whether there are any associations between these disturbances. In this retrospective cohort study, consecutive patients with functional gastrointestinal symptoms suggestive of gastric neuromuscular dysfunction (gastroparesis or functional dyspepsia) underwent clinical assessment, gastric scintigraphy, oesophageal high-resolution manometry and ambulatory pH monitoring using standard protocols. We studied 61 patients with various functional upper gastrointestinal symptoms who underwent gastric scintigraphy, oesophageal high-resolution manometry and ambulatory pH monitoring. Forty-four patients exhibited gastroparesis by gastric scintigraphy. Oesophageal motility disorders were found in 68% and 42% of patients with or without scintigraphic evidence of gastroparesis respectively, suggesting of overlapping gastric and oesophageal neuromuscular disorder. Forty-three per cent of patients with gastroparesis had abnormal oesophageal acid exposure with mean % pH <4.0 of 7.5 in contrast to 38% of those symptomatic controls with normal gastric emptying, with mean %pH <4.0 of 5.4 (NS). Symptoms of epigastric pain, heartburn/regurgitation, bloating, nausea, vomiting, dysphagia, belching and weight loss could not distinguish patients with or without gastroparesis, although weight loss was significantly more prevalent and severe (p<0.002) in patients with gastroparesis. There was no relationship between oesophageal symptoms and motor or pH abnormalities in either groups. Irrespective of gastric emptying delay by scintigraphy, patients with symptoms suggestive of gastric neuromuscular dysfunction have a high prevalence of oesophageal motor disorder and pathological oesophageal acid exposure that may contribute to their symptoms and may require therapy. High-resolution oesophageal manometry and pH monitoring are non-invasive and potentially useful in the assessment and management of these patients.

An Experimental Comparison of the Effects of Zostera marina and Zostera japonica on the Diurnal Variability of the Carbonate System in the Context of a Pacific Northwest Estuary

NASA Astrophysics Data System (ADS)

Miller, C.; Love, B. A.; Yang, S.

2016-02-01

Atmospheric CO2 emissions are being absorbed at an unprecedented rate by the global and coastal oceans, shifting the baseline pCO2, and inducing anthropogenic ocean acidification (OA). Recent studies have highlighted the potential benefits of near-shore vegetated habitats, such as seagrass beds as carbon sinks, potentially mitigating the effects of OA for vulnerable calcifying organisms. Seagrasses are capable of raising seawater pH and CaCO3 saturation state during times of high photosynthetic activity; however, the converse occurs during periods of dark respiration, resulting in a cyclical pattern of high and low pH and saturation state. A better understanding of diurnal seagrass induced carbonate system variability is needed to determine whether seagrass beds act as refugia from OA, and if individual species differentially affect the carbonate system. We conducted experiments to compare the effects of the native Zostera marina and non-native Zostera japonica on the carbonate system. Leaf clippings were incubated at five different light intensities (including dark) and pCO2 levels, representing the range of light and pCO2 in a given day. Induced changes in dissolved inorganic carbon (DIC) via photosynthesis and respiration were measured as well as pH and alkalinity. As irradiance and concentration of bio-available inorganic carbon are the two main drivers of photosynthetic activity, our measurements of the short-term response of photosynthesis to a spectrum of pCO2 and irradiance intensity can predict the diurnal fluctuation of pH and DIC for both species. This lab study provides a mechanistic background for building complex models based on field monitoring of carbonate chemistry in seagrass communities by comparing and integrating our results with in situ measurements. Interpretation of our findings will be placed in the context of short-term seagrass response to the spatiotemporal variability of pCO2 with respect to the progression of ocean acidification.

Membrane-aerated microbioreactor for high-throughput bioprocessing.

PubMed

Zanzotto, Andrea; Szita, Nicolas; Boccazzi, Paolo; Lessard, Philip; Sinskey, Anthony J; Jensen, Klavs F

2004-07-20

A microbioreactor with a volume of microliters is fabricated out of poly(dimethylsiloxane) (PDMS) and glass. Aeration of microbial cultures is through a gas-permeable PDMS membrane. Sensors are integrated for on-line measurement of optical density (OD), dissolved oxygen (DO), and pH. All three parameter measurements are based on optical methods. Optical density is monitored via transmittance measurements through the well of the microbioreactor while dissolved oxygen and pH are measured using fluorescence lifetime-based sensors incorporated into the body of the microbioreactor. Bacterial fermentations carried out in the microbioreactor under well-defined conditions are compared to results obtained in a 500-mL bench-scale bioreactor. It is shown that the behavior of the bacteria in the microbioreactor is similar to that in the larger bioreactor. This similarity includes growth kinetics, dissolved oxygen profile within the vessel over time, pH profile over time, final number of cells, and cell morphology. Results from off-line analysis of the medium to examine organic acid production and substrate utilization are presented. By changing the gaseous environmental conditions, it is demonstrated that oxygen levels within the microbioreactor can be manipulated. Furthermore, it is demonstrated that the sensitivity and reproducibility of the microbioreactor system are such that statistically significant differences in the time evolution of the OD, DO, and pH can be used to distinguish between different physiological states. Finally, modeling of the transient oxygen transfer within the microbioreactor based on observed and predicted growth kinetics is used to quantitatively characterize oxygen depletion in the system. Copyright 2004 Wiley Periodicals, Inc.

Can Sequential Coagulation Monitoring Predict Major Haemorrhage in Extremely Low Birth Weight Infants?

PubMed

Thanhaeuser, Margarita; Binder, Christoph; Derhaschnig, Ulla; Jilma, Bernd; Kornsteiner-Krenn, Margit; Huber-Dangl, Mercedes; Repa, Andreas; Kreissl, Alexandra; Berger, Angelika; Haiden, Nadja

2018-06-04

 Bleeds such as intra-ventricular (IVH) and pulmonary haemorrhage (PH) are life-threatening events in extremely low birth weight (ELBW) infants. Serial coagulation monitoring by measuring the international normalized ratio (INR) with small volume samples might facilitate early diagnosis and possibly prevent major bleeds.  This was a prospective longitudinal study performed in ELBW infants, who received serial INR monitoring by point of care testing during their first 30 days of life. The primary objective was to explore whether INR monitoring could predict major bleeding events (IVH, PH). Secondary objectives were mortality and feasibility in this patient population.  A total of 127 ELBW infants were stratified into a bleeding and a non-bleeding group. Bleeding events occurred in 31% (39/127) of the infants, whereupon 24% developed IVH and 9% PH. Infants in the bleeding group were 4 days younger at birth ( p  = 0.05) and had a substantially higher mortality rate of 26% versus 5% in controls ( p  = 0.005). Median INR during the first 3 days before a bleeding event was 1.55 (95% confidence interval [CI]: 1.39-1.74) compared with the control group with 1.45 (95% CI: 1.44-1.58; p  = 0.81). Platelet counts were significantly lower in the bleeding group on the 3rd day and during the 2nd to 4th week of life.  Serial coagulation monitoring by an INR point of care testing is feasible in ELBW infants but could not predict bleeding events. Further studies with daily monitoring of INR and platelet counts during the first days of life might be able to more precisely detect a risk of major haemorrhage in ELBW infants. Schattauer GmbH Stuttgart.

Metabolic Potential and Activity in Fluids of the Coast Range Ophiolite Microbial Observatory, California, USA

NASA Technical Reports Server (NTRS)

Hoehler, T.; Som, S.; Schrenk, M.; McCollom, T.; Cardace, D.

2016-01-01

Metabolic potential and activity associated with hydrogen and carbon monoxide were characterized in fluids sampled from the the Coast Range Ophiolite Microbial Observatory (CROMO). CROMO consists of two clusters of science-dedicated wells drilled to varying depths up to 35m in the actively serpentinizing, Jurassic-age Coast Range Ophiolite of Northern California, along with a suite of pre-existing monitoring wells at the same site. Consistent with the fluid chemistry observed in other serpentinizing systems, CROMO fluids are highly alkaline, with pH up to 12.5, high in methane, with concentrations up 1600 micromolar, and low in dissolved inorganic carbon (DIC), with concentrations of 10's to 100's of micromolar. CROMO is conspicuous for fluid H2 concentrations that are consistently sub-micromolar, orders of magnitude lower than is typical of other systems. However, higher H2 concentrations (10's -100's of micromolar) at an earlier stage of fluid chemical evolution are predicted by, or consistent with: thermodynamic models for fluid chemistry based on parent rock composition equivalent to local peridotite and with water:rock ratio constrained by observed pH; the presence of magnetite at several wt% in CROMO drill cores; and concentrations of formate and carbon monoxide that would require elevated H2 if formed in equilibrium with H2 and DIC. Calculated Gibbs energy changes for reaction of H2 and CO in each of several metabolisms, across the range of fluid composition encompassed by the CROMO wells, range from bioenergetically feasible (capable of driving ATP synthesis) to thermodynamically unfavorable. Active consumption relative to killed controls was observed for both CO and H2 during incubation of fluids from the pre-existing monitoring wells; in incubations of freshly cored solids, consumption was only observed in one sample set (corresponding to the lowest pH) out of three. The specific metabolisms by which H2 and CO are consumed remain to be determined.

Assessing the efficacy of immunotherapy with a glutaraldehyde-modified house dust mite extract in children by monitoring changes in clinical parameters and inflammatory markers in exhaled breath.

PubMed

Lozano, Jaime; Cruz, María-Jesús; Piquer, Mónica; Giner, Maria-Teresa; Plaza, Ana María

2014-01-01

The aim of this study was to evaluate the effectiveness of specific immunotherapy (SIT) management with allergoids in children with allergic asthma by monitoring changes in clinical parameters and inflammatory markers in exhaled breath. The study population included 43 patients (24 males) of 6-14 years of age, who had allergic asthma and were sensitized to mites. Twenty-three individuals were treated with subcutaneous SIT (PURETHAL® Mites, HAL Allergy) for 8 months, i.e. the SIT group, and 20 were given medication to treat symptoms only, i.e. the control group. Before treatment and after 4 and 8 months, several clinical parameters, the levels of exhaled nitric oxide and the pH of exhaled breath condensate (EBC) were determined. The SIT group presented with an improvement in asthma classification, a reduction in maintenance drug therapy and improved scores on the quality-of-life questionnaire. These changes were not observed in the control group. Both groups presented significant decreases in EBC pH values at 4 and 8 months after treatment compared to at baseline. However, analysis of the variable 'ratio' showed an increase in the EBC pH values after 8 months of treatment in the SIT group compared with the values at 4 months. SIT with standardized mite extract reduces asthma symptoms in children. A decrease in EBC pH values was observed in both groups, although the SIT group presented a tendency of recovered values after 8 months. Future studies of EBC pH monitoring in the longer term are needed to determine the effectiveness of this marker. © 2014 S. Karger AG, Basel.

Influence of environmental, structural, and behavioral factors on the presence of phosphine in worker areas during fumigations in grain elevators.

PubMed

Reed, C

2001-02-01

Data-logging gas monitors with electrochemical cells sensitive to phosphine (PH3) were used to characterize concentrations of this common grain fumigant in and around grain elevators during fumigations. Twenty-four grain fumigations were observed, and each was monitored over a 5- to 8-day period. Phosphine gas, generated from aluminum phosphide fumigant applied to the grain, generally moved upward toward the grain surface and exited the bin at bin-top openings to the outside air or to enclosed worker areas. The upward air currents appeared to be the result of chimney effects, e.g., pressure differences resulting from buoyant air inside the warm grain and cooler, denser, ambient air. Significant wind effects on the PH3 concentration were also observed in the air between the grain surface and the bin roof. In enclosed areas located at the bin-top level, monitors located near the fill port or the fumigant dispenser recorded PH3 concentrations in excess of the exposure limit of 0.3 parts per million (ppm) about 35% of the time during grain fumigations. Phosphine concentrations between 0.31 and 1.0 ppm were observed 17.3% of the time, and concentrations in the ranges of 1.01-3.0, 3.01-10.0, and >10 ppm constituted 11.8%, 5.5%, and 0.3% of all readings, respectively, in bin-top worker areas. The likelihood of recording PH3 concentrations >0.3 ppm depended on ventilation practices. Fans in tunnels and open windows at aboveground locations appeared to greatly reduce the likelihood of high PH3 concentrations in enclosed areas.

In vivo measurements of changes in pH triggered by oxalic acid in leaf tissue of transgenic oilseed rape.

PubMed

Zou, Qiu-Ju; Liu, Sheng-Yi; Dong, Xu-Yan; Bi, Yan-Hua; Cao, Yuan-Cheng; Xu, Qiao; Zhao, Yuan-Di; Chen, Hong

2007-01-01

Oxalic acid (OA), a non-host-specific toxin secreted by Sclerotinia sclerotiorum during pathogenesis, has been demonstrated to be a major phytotoxic and pathogenic factor. Oxalate oxidase (OXO) is an enzyme associated with the detoxification of OA, and hence the introduction of an OXO gene into oilseed rape (Brassica napus L.) to break down OA may be an alternative way of increasing the resistance of the plant to Sclerotinia sclerotiorum. In order to investigate the activation of OXO in transgenic oilseed rape, a convenient and accessible method was used to monitor changes in pH in response to stress induced by OA. The pH sensor, a platinum microcylinder electrode modified using polyaniline film, exhibited a linear response within the pH range from 3 to 7, with a Nernst response slope of 70 mV/pH at room temperature. The linear correlation coefficient was 0.9979. Changes induced by OA in the pH values of leaf tissue of different oilseed rape species from Brassica napus L. were monitored in real time in vivo using this electrode. The results clearly showed that the transgenic oilseed rape was more resistant to OA than non-transgenic oilseed rape. Copyright (c) 2007 John Wiley & Sons, Ltd.

Guidance for Habitat Restoration Monitoring: Framework for Monitoring Plan Development and Implementation (User’s Guide)

DTIC Science & Technology

2004-08-01

release; distribution is unlimited. ENGINEERING SERVICE CENTER Port Hueneme, California 93043-4370 (This page intentionally blank.) REPORT DOCUMENTATION...responses. For example, an extended period of drought may greatly retard, set back, or even prevent establishment of a desired plant species or...Categories of Potential Chemical Monitoring Dataa Monitoring Variable Habitat Type Water Quality pH REDOX DO Salinity Freshwater wetlands S−M S–M M S–M

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

PubMed

Østergaard, Jesper; Jensen, Henrik; Larsen, Susan W; Larsen, Claus; Lenke, Jim

2014-11-01

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. Copyright © 2014 Elsevier B.V. All rights reserved.

A novel pH optical sensor using methyl orange based on triacetylcellulose membranes as support.

PubMed

Hosseini, Mohammad; Heydari, Rouhollah; Alimoradi, Mohammad

2014-07-15

A novel pH optical sensor based on triacetylcellulose membrane as solid support was developed by using immobilization of methyl orange indicator. The prepared optical sensor was fixed into a flow cell for on-line pH monitoring. Variables affecting sensor performance, such as pH of dye bonding to triacetylcellulose membrane and dye concentration have been fully evaluated and optimized. The calibration curve showed good behavior and precision (RSD<0.4%) in the pH range of 4.0-12.0. No significant variation was observed on sensor response with increasing the ionic strength in the range of 0.0-0.5M of sodium chloride. Determination of pH by using the proposed optical sensor is on-line, quick, inexpensive, selective and sensitive in the pH range of 4.0-12.0. Copyright © 2014 Elsevier B.V. All rights reserved.

Extra-esophageal gastroesophageal reflux disease and asthma: understanding this interplay.

PubMed

Naik, Rishi D; Vaezi, Michael F

2015-07-01

Gastroesophageal reflux disease (GERD) is a condition that develops when there is reflux of stomach contents, which typically manifests as heartburn and regurgitation. These esophageal symptoms are well recognized; however, there are extra-esophageal manifestations of GERD, which include asthma, chronic cough, laryngitis and sinusitis. With the rising incidence of asthma, there is increasing interest in identifying how GERD impacts asthma development and therapy. Due to the poor sensitivity of endoscopy and pH monitoring, empiric therapy with proton pump inhibitors (PPIs) is now considered the initial diagnostic step in patients suspected of having GERD-related symptoms. If unresponsive, diagnostic testing with pH monitoring off therapy and/or impedance/pH monitoring on therapy, may be reasonable in order to assess for baseline presence of reflux with the former and exclude continued acid or weakly acid reflux with the latter tests. PPI-unresponsive asthmatics, without overt regurgitation, usually have either no reflux or causes other than GERD. In this group, PPI therapy should be discontinued. In those with GERD as a contributing factor acid suppressive therapy should be continued as well as optimally treating other etiologies requiring concomitant treatment. Surgical fundoplication is rarely needed but in those with a large hiatal hernia, moderate-to-severe reflux by pH monitoring surgery might be helpful in eliminating the need for high-dose acid suppressive therapy.

Analyses of the Post-reflux Swallow-induced Peristaltic Wave Index and Nocturnal Baseline Impedance Parameters Increase the Diagnostic Yield of Impedance-pH Monitoring of Patients With Reflux Disease.

PubMed

Frazzoni, Marzio; Savarino, Edoardo; de Bortoli, Nicola; Martinucci, Irene; Furnari, Manuele; Frazzoni, Leonardo; Mirante, Vincenzo Giorgio; Bertani, Helga; Marchi, Santino; Conigliaro, Rita; Savarino, Vincenzo

2016-01-01

Analyses of impedance parameters such as the post-reflux swallow-induced peristaltic wave (PSPW) index and the mean nocturnal baseline impedance (MNBI) have been proposed to increase the accuracy of diagnosis of reflux disease. We assessed whether these improve the diagnostic yield of impedance pH monitoring of reflux disease. We performed a prospective study of consecutive patients with proton pump inhibitor-responsive heartburn who underwent 24-hour impedance pH monitoring at hospitals in Italy from January 2011 through December 2013. Reviewers blindly analyzed off-therapy impedance pH tracings from 289 patients with proton pump inhibitor-responsive heartburn, 68 with erosive reflux disease and 221 with non-erosive reflux disease (NERD), along with 50 healthy individuals (controls). The PSPW index, the MNBI, the esophageal acid exposure time, the number of total refluxes, and the bolus exposure were calculated, as well as the symptom association probability (SAP) and the symptom index (SI). In receiver operating characteristic analysis, the area under curve of the PSPW index (0.977; 95% confidence interval, 0.961-0.993) was significantly greater than that of the other impedance pH parameters in identifying patients with reflux disease (P < .001). The PSPW index and the MNBI identified patients with erosive reflux disease with the highest level of sensitivity (100% and 91%, respectively), as well as the 118 pH-positive (99% and 86%) and 103 pH-negative (77% and 56%) cases of NERD. The PSPW index and the MNBI identified pH-negative NERD with the highest level of sensitivity; values were 82% and 52% for the 65 SAP-positive and/or SI-positive cases and 68% and 63% for the 38 SAP-negative and SI-negative cases. Diagnoses of NERD were confirmed by pH-only criteria, including those that were positive on the basis of the SAP or SI, for 165 of 221 cases (75%) and by impedance pH criteria for 216 of 221 cases (98%) (P = .001). The PSPW index and the MNBI increase the diagnostic yield of impedance pH monitoring of patients with reflux disease. Analysis of impedance pH data by calculating the PSPW index and the MNBI can increase the accuracy of diagnosis of patients with reflux disease, compared with pH-only data. Copyright © 2016 AGA Institute. Published by Elsevier Inc. All rights reserved.

Proton-sensing transistor systems for detecting ion leakage from plasma membranes under chemical stimuli.

PubMed

Imaizumi, Yuki; Goda, Tatsuro; Schaffhauser, Daniel F; Okada, Jun-Ichi; Matsumoto, Akira; Miyahara, Yuji

2017-03-01

The membrane integrity of live cells is routinely evaluated for cytotoxicity induced by chemical or physical stimuli. Recent progress in bioengineering means that high-quality toxicity validation is required. Here, we report a pH-sensitive transistor system developed for the continuous monitoring of ion leakage from cell membranes upon challenge by toxic compounds. Temporal changes in pH were generated with high reproducibility via periodic flushing of HepG2 cells on a gate insulator of a proton-sensitive field-effect transistor with isotonic buffer solutions with/without NH 4 Cl. The pH transients at the point of NH 4 Cl addition/withdrawal originated from the free permeation of NH 3 across the semi-permeable plasma membranes, and the proton sponge effect produced by the ammonia equilibrium. Irreversible attenuation of the pH transient was observed when the cells were subjected to a membrane-toxic reagent. Experiments and simulations proved that the decrease in the pH transient was proportional to the area of the ion-permeable pores on the damaged plasma membranes. The pH signal was correlated with the degree of hemolysis produced by the model reagents. The pH assay was sensitive to the formation of molecularly sized pores that were otherwise not measurable via detection of the leakage of hemoglobin, because the hydrodynamic radius of hemoglobin was greater than 3.1nm in the hemolysis assay. The pH transient was not disturbed by inherent ion-transporter activity. The ISFET assay was applied to a wide variety of cell types. The system presented here is fast, sensitive, practical and scalable, and will be useful for validating cytotoxins and nanomaterials. The plasma membrane toxicity and hemolysis are widely and routinely evaluated in biomaterials science and biomedical engineering. Despite the recent development of a variety of methods/materials for efficient gene/drug delivery systems to the cytosol, the methodologies for safety validation remain unchanged in many years while leaving some major issues such as sensitivity, accuracy, and fast response. The paper describes a new way of measuring the plasma membrane leakage in real time upon challenge by toxic reagents using a solid-state transistor that is sensitive to proton as the smallest indicator. Our system was reliable and was correlated to the results from hemolysis assay with advanced features in sensitivity, fast response, and wide applicability to chemical species. The downsizing and integration features of semiconductor fabrication technologies may realize cytotoxicity assays at the single-cell level in multi-parallel. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Randomized prospective evaluation of cimetidine and antacid control of gastric pH in the critically ill.

PubMed Central

Stothert, J C; Simonowitz, D A; Dellinger, E P; Farley, M; Edwards, W A; Blair, A D; Cutler, R; Carrico, C J

1980-01-01

One hundred forty-four critically ill patients admitted to an intensive care setting were randomly assigned to cimetidine or antacid treatament groups. Gastric pH was monitored hourly. One hundred twenty-three (85%) patients demonstrated a fall in pH to less than 4 and were considered to require prophylaxis. Prophylaxis was considered adequate if the measured pH could then be maintained at greater than or equal to 4. Fifty-eight patients received antacids alone, the average requirement being 41 cc/hour. Sixty-five patients received cimetidine. Seventeen (26%) of the cimetidine prophylaxis patients failed to raise their pH and were than placed on hourly administration of antacid with successful elevations of pH to greater than or equal to 4 in all cases on an average supplementary dose of 53 cc/hour. Risk factors, including sepsis, hypotension, head injury, respiratory failure, degree of trauma, and age, were not statistically different in the two treated groups. Using these same criteria, responders to cimetidine could not be differentiated from nonresponders. All patients were protected from significant stress bleeding while on this study. Significant complications of either treatment were minimal. Antacids offered consistent protection against gastric acidity and were 100% effective. A routine schedule of 300 mg every six hours of cimetidine was effective in only 47% of patients, and the maximum dose of cimetidine was effective in only 74% of patients. Hourly measurement of intragastric pH is required for monitoring the response to prophylaxis of stress bleeding in severely ill patients. PMID:7406571

Non-Contact Conductivity Measurement for Automated Sample Processing Systems

NASA Technical Reports Server (NTRS)

Beegle, Luther W.; Kirby, James P.

2012-01-01

A new method has been developed for monitoring and control of automated sample processing and preparation especially focusing on desalting of samples before analytical analysis (described in more detail in Automated Desalting Apparatus, (NPO-45428), NASA Tech Briefs, Vol. 34, No. 8 (August 2010), page 44). The use of non-contact conductivity probes, one at the inlet and one at the outlet of the solid phase sample preparation media, allows monitoring of the process, and acts as a trigger for the start of the next step in the sequence (see figure). At each step of the muti-step process, the system is flushed with low-conductivity water, which sets the system back to an overall low-conductivity state. This measurement then triggers the next stage of sample processing protocols, and greatly minimizes use of consumables. In the case of amino acid sample preparation for desalting, the conductivity measurement will define three key conditions for the sample preparation process. First, when the system is neutralized (low conductivity, by washing with excess de-ionized water); second, when the system is acidified, by washing with a strong acid (high conductivity); and third, when the system is at a basic condition of high pH (high conductivity). Taken together, this non-contact conductivity measurement for monitoring sample preparation will not only facilitate automation of the sample preparation and processing, but will also act as a way to optimize the operational time and use of consumables

Wearable, Flexible, and Multifunctional Healthcare Device with an ISFET Chemical Sensor for Simultaneous Sweat pH and Skin Temperature Monitoring.

PubMed

Nakata, Shogo; Arie, Takayuki; Akita, Seiji; Takei, Kuniharu

2017-03-24

Real-time daily healthcare monitoring may increase the chances of predicting and diagnosing diseases in their early stages which, currently, occurs most frequently during medical check-ups. Next-generation noninvasive healthcare devices, such as flexible multifunctional sensor sheets designed to be worn on skin, are considered to be highly suitable candidates for continuous real-time health monitoring. For healthcare applications, acquiring data on the chemical state of the body, alongside physical characteristics such as body temperature and activity, are extremely important for predicting and identifying potential health conditions. To record these data, in this study, we developed a wearable, flexible sweat chemical sensor sheet for pH measurement, consisting of an ion-sensitive field-effect transistor (ISFET) integrated with a flexible temperature sensor: we intend to use this device as the foundation of a fully integrated, wearable healthcare patch in the future. After characterizing the performance, mechanical flexibility, and stability of the sensor, real-time measurements of sweat pH and skin temperature are successfully conducted through skin contact. This flexible integrated device has the potential to be developed into a chemical sensor for sweat for applications in healthcare and sports.

Measuring Synaptic Vesicle Endocytosis in Cultured Hippocampal Neurons.

PubMed

Villarreal, Seth; Lee, Sung Hoon; Wu, Ling-Gang

2017-09-04

During endocytosis, fused synaptic vesicles are retrieved at nerve terminals, allowing for vesicle recycling and thus the maintenance of synaptic transmission during repetitive nerve firing. Impaired endocytosis in pathological conditions leads to decreases in synaptic strength and brain functions. Here, we describe methods used to measure synaptic vesicle endocytosis at the mammalian hippocampal synapse in neuronal culture. We monitored synaptic vesicle protein endocytosis by fusing a synaptic vesicular membrane protein, including synaptophysin and VAMP2/synaptobrevin, at the vesicular lumenal side, with pHluorin, a pH-sensitive green fluorescent protein that increases its fluorescence intensity as the pH increases. During exocytosis, vesicular lumen pH increases, whereas during endocytosis vesicular lumen pH is re-acidified. Thus, an increase of pHluorin fluorescence intensity indicates fusion, whereas a decrease indicates endocytosis of the labelled synaptic vesicle protein. In addition to using the pHluorin imaging method to record endocytosis, we monitored vesicular membrane endocytosis by electron microscopy (EM) measurements of Horseradish peroxidase (HRP) uptake by vesicles. Finally, we monitored the formation of nerve terminal membrane pits at various times after high potassium-induced depolarization. The time course of HRP uptake and membrane pit formation indicates the time course of endocytosis.

[Changes in PCO2 and pH gradients in a canine model of experimental acute hemorrhage].

PubMed

Rabanal, J M; Mons, R; Galindo, M; Solares, G; Seco, I; García-Castrillo, L

1999-01-01

To study changes in arterial-venous PCO2 pressures (Da-vPCO2) and in pH (Da-vpH) in an experimental dog model of acute bleeding. To emphasize the utility of monitoring these variables in situations of acute bleeding. ANIMALS AND METHOD: Eighteen dogs were anesthesized and monitored while being subjected to gradual bleeding. Gasometric and hemodynamic variables were recorded at the following moments: baseline, stage I (15% of volemic loss), stage Ib (20%), stage II (25%), stage IIb (30%) and stage III (35%). No significant differences in pH or PCO2 in either arterial or mixed venous blood were found. Bleeding induced a constant and progressive increase in Da-vPCO2 that correlated with changes in volume (r = -0.56, p < 0.001), SvO2 (r = 0.71; p < 0.001), Da-vO2 gradient (r = 0.62; p < 0.001) and cardiac output (r = 0.63; p < 0.001). Gradual bleeding caused a constant and significant increase of Da-vPCO2. Monitoring such changes in states of circulatory insufficiency may be useful for evaluating tissue ischemia.

Development of a CO 2 Chemical Sensor for Downhole CO 2 Monitoring in Carbon Sequestration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Ning

Geologic storage of carbon dioxide (CO 2) has been proposed as a viable means for reducing anthropogenic CO 2 emissions. The means for geological sequestration of CO 2 is injection of supercritical CO 2 underground, which requires the CO 2 to remain either supercritical, or in solution in the water/brine present in the underground formation. However, there are aspects of geologic sequestration that need further study, particularly in regards to safety. To date, none of the geologic sequestration locations have been tested for storage integrity under the changing stress conditions that apply to the sequestration of very large amounts ofmore » CO 2. Establishing environmental safety and addressing public concerns require widespread monitoring of the process in the deep subsurface. In addition, studies of subsurface carbon sequestration such as flow simulations, models of underground reactions and transports require a comprehensive monitoring process to accurately characterize and understand the storage process. Real-time information about underground CO 2 movement and concentration change is highly helpful for: (1) better understanding the uncertainties present in CO 2 geologic storage; (2) improvement of simulation models; and (3) evaluation of the feasibility of geologic CO 2 storage. Current methods to monitor underground CO 2 storage include seismic, geoelectric, isotope and tracer methods, and fluid sampling analysis. However, these methods commonly resulted low resolution, high cost, and the inability to monitor continuously over the long time scales of the CO 2 storage process. A preferred way of monitoring in-situ underground CO 2 migration is to continuous measure CO 2 concentration change in brine during the carbon storage process. An approach to obtain the real time information on CO 2 concentration change in formation solution is highly demanded in carbon storage to understand the CO 2 migration subsurface and to answer the public safety problem. The objective of the study is to develop a downhole CO 2 sensor that can in-situ, continuously monitor CO 2 concentration change in deep saline. The sensor is a Severinghaus-type CO 2 sensor with small size, which renders it can be embedded in monitoring well casing or integrated with pressure/temperature transducers, enabling the development of “smart” wells. The studies included: (1) prepare and characterize metal-oxide electrodes. Test the electrodes response to pH change. Investigate different ions and brine concentration effects on the electrode’s performance. Study the stability of the electrode in brine solution; (2) fabricate a downhole CO 2 sensor with the metal-oxide electrodes prepared in the laboratory. Test the performance of the CO 2 sensor in brine solutions. Study high pressure effects on the performance of the sensor; (3) design and conduct CO 2/brine coreflooding experiments with the CO2 sensor. Monitor CO 2 movement along the core and test the performance of the sensor in coreflooding tests. Develop a data acquisition system that can digitize the sensor’s output voltage. Our completed research has resulted in deep understanding of downhole CO 2 sensor development and CO 2 monitoring in CO 2 storage process. The developed downhole CO 2 sensor included a metal-oxide electrode, a gas-permeable membrane, a porous steel cup, and a bicarbonate-based internal electrolyte solution. Iridium oxide-based electrode was prepared and used for preparation the CO 2 sensor. The prepared iridium oxide-based electrode displayed a linearly response to pH change. Different factors such as different ions and ions concentration, temperature, and pressure effects on the electrode performance on pH response were investigated. The results indicated that the electrode exhibited a good performance even in high salt concentration of produced water. To improve the electrode performance under high pressure, IrO 2 nanoparticles with the particle size in the range of 1-2 nm were prepared and electrodeposited on stainless steel substrate by cyclic voltammetry. It was observed that the thin film of iridium oxide was formed on the substrate surface and such iridium oxide-based electrode displayed excellent performance under high pressure for longer term. A downhole CO 2 sensor with the iridium oxide-based electrode was prepared. The working principle of the CO 2 sensor is based on the measurement of the pH change of the internal electrolyte solution caused by the hydrolysis of CO 2 and then determination of the CO 2 concentration in water. The prepared downhole CO 2 sensor had the size of diameter of 0.7 in. and length of 1.5 in. The sensor was tested under the pressures of 500 psi, 2,000 psi, and 3,000 psi. A linear correlation was observed between the sensor potential change and dissolved CO 2 concentration in water. The response time of the CO 2 sensor was in the range of 60-100 minutes. Further tests indicated that the CO 2 sensor exhibited good reproducibility under high pressure. A CO 2/brine coreflooding system was constructed to simulate the real-world CO 2 storage process. The prepared downhole CO 2 sensor was loaded in the system to monitor CO 2 movement during CO 2/brine coreflooding test. The results indicated that the sensor could detect CO 2 movement in the tests. Further studies showed that the sensor could be recovered by brine flooding after CO 2/brine flushed the core. The results of the coreflooding tests demonstrated that the sensor had potential application for CO 2 monitoring in carbon sequestration. A data acquisition system for the downhoe CO 2 sensor was developed and coded. The system converted the sensor output signal into digital data and transported the data from downhole to wellhead surface. The data acquisition system was tested and evaluated in the laboratory with the prepared sensor for data collection.« less

PhOTO Zebrafish: A Transgenic Resource for In Vivo Lineage Tracing during Development and Regeneration

PubMed Central

Dempsey, William P.; Fraser, Scott E.; Pantazis, Periklis

2012-01-01

Background Elucidating the complex cell dynamics (divisions, movement, morphological changes, etc.) underlying embryonic development and adult tissue regeneration requires an efficient means to track cells with high fidelity in space and time. To satisfy this criterion, we developed a transgenic zebrafish line, called PhOTO, that allows photoconvertible optical tracking of nuclear and membrane dynamics in vivo. Methodology PhOTO zebrafish ubiquitously express targeted blue fluorescent protein (FP) Cerulean and photoconvertible FP Dendra2 fusions, allowing for instantaneous, precise targeting and tracking of any number of cells using Dendra2 photoconversion while simultaneously monitoring global cell behavior and morphology. Expression persists through adulthood, making the PhOTO zebrafish an excellent tool for studying tissue regeneration: after tail fin amputation and photoconversion of a ∼100µm stripe along the cut area, marked differences seen in how cells contribute to the new tissue give detailed insight into the dynamic process of regeneration. Photoconverted cells that contributed to the regenerate were separated into three distinct populations corresponding to the extent of cell division 7 days after amputation, and a subset of cells that divided the least were organized into an evenly spaced, linear orientation along the length of the newly regenerating fin. Conclusions/Significance PhOTO zebrafish have wide applicability for lineage tracing at the systems-level in the early embryo as well as in the adult, making them ideal candidate tools for future research in development, traumatic injury and regeneration, cancer progression, and stem cell behavior. PMID:22431986

Urea biosensor for hemodialysis monitoring

DOEpatents

Glass, Robert S.

1999-01-01

An electrochemical sensor capable of detecting and quantifying urea in fluids resulting from hemodialysis procedures. The sensor is based upon measurement of the pH change produced in an aqueous environment by the products of the enzyme-catalyzed hydrolysis of urea. The sensor may be fabricated using methods amenable to mass fabrication, resulting in low-cost sensors and thus providing the potential for disposable use. In a typical application, the sensor could be used in treatment centers, in conjunction with an appropriate electronics/computer system, in order to determine the hemodialysis endpoint. The sensor can also be utilized to allow at-home testing to determine if dialysis was necessary. Such a home monitor is similar, in principle, to devices used for blood glucose testing by diabetics, and would require a blood droplet sample by using a finger prick.

Characterization of Industrial Coolant Fluids and Continuous Ageing Monitoring by Wireless Node-Enabled Fiber Optic Sensors.

PubMed

Sachat, Alexandros El; Meristoudi, Anastasia; Markos, Christos; Sakellariou, Andreas; Papadopoulos, Aggelos; Katsikas, Serafim; Riziotis, Christos

2017-03-11

Environmentally robust chemical sensors for monitoring industrial processes or infrastructures are lately becoming important devices in industry. Low complexity and wireless enabled characteristics can offer the required flexibility for sensor deployment in adaptable sensing networks for continuous monitoring and management of industrial assets. Here are presented the design, development and operation of a class of low cost photonic sensors for monitoring the ageing process and the operational characteristics of coolant fluids used in an industrial heavy machinery infrastructure. The chemical, physical and spectroscopic characteristics of specific industrial-grade coolant fluids were analyzed along their entire life cycle range, and proper parameters for their efficient monitoring were identified. Based on multimode polymer or silica optical fibers, wide range (3-11) pH sensors were developed by employing sol-gel derived pH sensitive coatings. The performances of the developed sensors were characterized and compared, towards their coolants' ageing monitoring capability, proving their efficiency in such a demanding application scenario and harsh industrial environment. The operating characteristics of this type of sensors allowed their integration in an autonomous wireless sensing node, thus enabling the future use of the demonstrated platform in wireless sensor networks for a variety of industrial and environmental monitoring applications.

Characterization of Industrial Coolant Fluids and Continuous Ageing Monitoring by Wireless Node—Enabled Fiber Optic Sensors

PubMed Central

El Sachat, Alexandros; Meristoudi, Anastasia; Markos, Christos; Sakellariou, Andreas; Papadopoulos, Aggelos; Katsikas, Serafim; Riziotis, Christos

2017-01-01

Environmentally robust chemical sensors for monitoring industrial processes or infrastructures are lately becoming important devices in industry. Low complexity and wireless enabled characteristics can offer the required flexibility for sensor deployment in adaptable sensing networks for continuous monitoring and management of industrial assets. Here are presented the design, development and operation of a class of low cost photonic sensors for monitoring the ageing process and the operational characteristics of coolant fluids used in an industrial heavy machinery infrastructure. The chemical, physical and spectroscopic characteristics of specific industrial-grade coolant fluids were analyzed along their entire life cycle range, and proper parameters for their efficient monitoring were identified. Based on multimode polymer or silica optical fibers, wide range (3–11) pH sensors were developed by employing sol-gel derived pH sensitive coatings. The performances of the developed sensors were characterized and compared, towards their coolants’ ageing monitoring capability, proving their efficiency in such a demanding application scenario and harsh industrial environment. The operating characteristics of this type of sensors allowed their integration in an autonomous wireless sensing node, thus enabling the future use of the demonstrated platform in wireless sensor networks for a variety of industrial and environmental monitoring applications. PMID:28287488

Temperature Effects on Biomass and Regeneration of Vegetation in a Geothermal Area

PubMed Central

Nishar, Abdul; Bader, Martin K.-F.; O’Gorman, Eoin J.; Deng, Jieyu; Breen, Barbara; Leuzinger, Sebastian

2017-01-01

Understanding the effects of increasing temperature is central in explaining the effects of climate change on vegetation. Here, we investigate how warming affects vegetation regeneration and root biomass and if there is an interactive effect of warming with other environmental variables. We also examine if geothermal warming effects on vegetation regeneration and root biomass can be used in climate change experiments. Monitoring plots were arranged in a grid across the study area to cover a range of soil temperatures. The plots were cleared of vegetation and root-free ingrowth cores were installed to assess above and below-ground regeneration rates. Temperature sensors were buried in the plots for continued soil temperature monitoring. Soil moisture, pH, and soil chemistry of the plots were also recorded. Data were analyzed using least absolute shrinkage and selection operator and linear regression to identify the environmental variable with the greatest influence on vegetation regeneration and root biomass. There was lower root biomass and slower vegetation regeneration in high temperature plots. Soil temperature was positively correlated with soil moisture and negatively correlated with soil pH. Iron and sulfate were present in the soil in the highest quantities compared to other measured soil chemicals and had a strong positive relationship with soil temperature. Our findings suggest that soil temperature had a major impact on root biomass and vegetation regeneration. In geothermal fields, vegetation establishment and growth can be restricted by low soil moisture, low soil pH, and an imbalance in soil chemistry. The correlation between soil moisture, pH, chemistry, and plant regeneration was chiefly driven by soil temperature. Soil temperature was negatively correlated to the distance from the geothermal features. Apart from characterizing plant regeneration on geothermal soils, this study further demonstrates a novel approach to global warming experiments, which could be particularly useful in low heat flow geothermal systems that more realistically mimic soil warming. PMID:28326088

Temperature Effects on Biomass and Regeneration of Vegetation in a Geothermal Area.

PubMed

Nishar, Abdul; Bader, Martin K-F; O'Gorman, Eoin J; Deng, Jieyu; Breen, Barbara; Leuzinger, Sebastian

2017-01-01

Understanding the effects of increasing temperature is central in explaining the effects of climate change on vegetation. Here, we investigate how warming affects vegetation regeneration and root biomass and if there is an interactive effect of warming with other environmental variables. We also examine if geothermal warming effects on vegetation regeneration and root biomass can be used in climate change experiments. Monitoring plots were arranged in a grid across the study area to cover a range of soil temperatures. The plots were cleared of vegetation and root-free ingrowth cores were installed to assess above and below-ground regeneration rates. Temperature sensors were buried in the plots for continued soil temperature monitoring. Soil moisture, pH, and soil chemistry of the plots were also recorded. Data were analyzed using least absolute shrinkage and selection operator and linear regression to identify the environmental variable with the greatest influence on vegetation regeneration and root biomass. There was lower root biomass and slower vegetation regeneration in high temperature plots. Soil temperature was positively correlated with soil moisture and negatively correlated with soil pH. Iron and sulfate were present in the soil in the highest quantities compared to other measured soil chemicals and had a strong positive relationship with soil temperature. Our findings suggest that soil temperature had a major impact on root biomass and vegetation regeneration. In geothermal fields, vegetation establishment and growth can be restricted by low soil moisture, low soil pH, and an imbalance in soil chemistry. The correlation between soil moisture, pH, chemistry, and plant regeneration was chiefly driven by soil temperature. Soil temperature was negatively correlated to the distance from the geothermal features. Apart from characterizing plant regeneration on geothermal soils, this study further demonstrates a novel approach to global warming experiments, which could be particularly useful in low heat flow geothermal systems that more realistically mimic soil warming.

Electrocatalyzed O2 response of myoglobin immobilized on multi-walled carbon nanotube forest electrodes.

PubMed

Pacios, M; del Valle, M; Bartroli, J; Esplandiu, M J

2009-10-01

Direct electrochemistry and activity of myoglobin (Mb) immobilized on carbon nanotube (CNT) forest electrodes were investigated by probing mainly its electrocatalytical response towards oxygen. The protein was anchored on the CNT electrodes through carbodiimide coupling, which was shown to provide long term stability. The electrochemical response was monitored as a function of oxygen concentration and pH. Conformational changes together with the consequent loss of oxygen affinity were recorded at low pH, which delimits the operative range of the Mb/CNT electrodes for sensing purposes. In general, it can be concluded that CNT forests constitute suitable platforms for Mb attachment without compromising the protein bioactivity and by keeping at the same time the direct electron exchange with the heme core. All these characteristics confer to the protein modified CNT system promising properties for the implementation of (bio)sensor devices with impact in the clinical and environmental field.

DNA-barcode directed capture and electrochemical metabolic analysis of single mammalian cells on a microelectrode array.

PubMed

Douglas, Erik S; Hsiao, Sonny C; Onoe, Hiroaki; Bertozzi, Carolyn R; Francis, Matthew B; Mathies, Richard A

2009-07-21

A microdevice is developed for DNA-barcode directed capture of single cells on an array of pH-sensitive microelectrodes for metabolic analysis. Cells are modified with membrane-bound single-stranded DNA, and specific single-cell capture is directed by the complementary strand bound in the sensor area of the iridium oxide pH microelectrodes within a microfluidic channel. This bifunctional microelectrode array is demonstrated for the pH monitoring and differentiation of primary T cells and Jurkat T lymphoma cells. Single Jurkat cells exhibited an extracellular acidification rate of 11 milli-pH min(-1), while primary T cells exhibited only 2 milli-pH min(-1). This system can be used to capture non-adherent cells specifically and to discriminate between visually similar healthy and cancerous cells in a heterogeneous ensemble based on their altered metabolic properties.

DNA-barcode directed capture and electrochemical metabolic analysis of single mammalian cells on a microelectrode array

PubMed Central

Douglas, Erik S.; Hsiao, Sonny C.; Onoe, Hiroaki; Bertozzi, Carolyn R.; Francis, Matthew B.; Mathies, Richard A.

2010-01-01

A microdevice is developed for DNA-barcode directed capture of single cells on an array of pH-sensitive microelectrodes for metabolic analysis. Cells are modified with membrane-bound single-stranded DNA, and specific single-cell capture is directed by the complementary strand bound in the sensor area of the iridium oxide pH microelectrodes within a microfluidic channel. This bifunctional microelectrode array is demonstrated for the pH monitoring and differentiation of primary T cells and Jurkat T lymphoma cells. Single Jurkat cells exhibited an extracellular acidification rate of 11 milli-pH min−1, while primary T cells exhibited only 2 milli-pH min−1. This system can be used to capture non-adherent cells specifically and to discriminate between visually similar healthy and cancerous cells in a heterogeneous ensemble based on their altered metabolic properties. PMID:19568668

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

PubMed

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.

Manufacture and application of RuO2 solid-state metal-oxide pH sensor to common beverages.

PubMed

Lonsdale, W; Wajrak, M; Alameh, K

2018-04-01

A new reproducible solid-state metal-oxide pH sensor for beverage quality monitoring is developed and characterised. The working electrode of the developed pH sensor is based on the use of laser-etched sputter-deposited RuO 2 on Al 2 O 3 substrate, modified with thin layers of sputter-deposited Ta 2 O 5 and drop-cast Nafion for minimisation of redox interference. The reference electrode is manufactured by further modifying a working electrode with a porous polyvinyl butyral layer loaded with fumed SiO 2 . The developed pH sensor shows excellent performance when applied to a selection of beverage samples, with a measured accuracy within 0.08 pH of a commercial glass pH sensor. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparison of accuracy and completeness of data obtained from three types of automatic water-quality monitors

USGS Publications Warehouse

Katzenbach, Max

1990-01-01

A comparison of data (specific conductance, dissolved-oxygen concentration, temperature, and pH) collected by the U.S. Geological Survey flowthrough monitor, the U.S. Geological Survey minimonitor, and a self-contained commercial 'packaged-sensor' system indicates that the data obtained by means of the most complete of the three systems. The U.S. Geological Survey flowthrough monitor is powered by 120-volt alternating current and in a heated weather-proof shelter. A pumping system brings water from the stream to sensors clustered in a sample clustered in a sample chamber located in the shelter. This instrument measures output from the senors; data are recorded in binary-coded decimal form on a 16-channel punched-paper tape recorder tape recorder housed in the shelter. The U.S. Geological Survey's minimonitor is powered by an external battery and is housed in a weatherproof shelter. This instrument measures output of instream sensors with extension cables having underwater connectors; data are recorded in binary-coded decimal form on a 16-channel punched-paper tape recorder housed in the shelter. The packaged-sensor system also measures output of senors housed in a packages that is submerged in the stream. It has internal power supply, no moving parts, and does not requires a weatherproof shelter; data are stored are stored in solid-state memory. Minimonitors were installed at four sites in Ohio where U.S. Geological survey flowthrough were in operation. Two package-sensor systems also were assigned to each site and were alternated every two weeks. Detailed records were kept of (1) field measurements, for comparison with monitor-system data from each instrument, and (2) equipment problems that resulted in loss of data. Results of the comparisons shows that the flow-through monitor gave the most accurate and the most complete data.

Expression of Na(+)/H(+) exchanger isoforms 1, 2, 3, and 4 in bovine endometrium and the influence of uterine pH at time of fixed-time AI of pregnancy success.

PubMed

Bolzenius, Jennifer K; Cushman, Robert A; Perry, George A

2016-08-01

Cows that exhibit estrus prior to fixed-time AI had increased sperm transport to the site of fertilization, and improved embryo quality on d 6 after insemination. Sperm transport is influenced by uterine pH, and research has reported that uterine pH decreased at onset of estrus, but must return to normal prior to ovulation. Therefore, the objectives of these studies were to investigate a possible mechanism for the regulation of uterine pH around the onset of estrus, and to determine if uterine pH at time of fixed-time AI influenced pregnancy success. In experiment 1, Angus-cross beef cows (n=40 and 28 in rep. 1 and 2, respectively) were synchronized with the PG 6-day CIDR protocol (PGF2α on d -9, GnRH and insertion of a CIDR on d -6, and PGF2α and CIDR removal on d 0). Cows were blocked by follicle size at time of CIDR removal, and uterine biopsies were collected at 0, 12, 24, 36, 48, 60 (Rep. 1), 72, 84, or 96h (Rep2) after CIDR removal, and total cellular RNA was extracted from all biopsies. Estrus was monitored by the HeatWatch Estrous Detection System. In experiment 2, 223 postpartum beef cows in 2 herds were synchronized with a fixed-time AI protocol (herd 1: n=97; CO-Synch plus CIDR protocol; herd 2: n=126; Co-synch protocol). Uterine pH was determined at time of AI (n=80 and 63 for herd 1 and 2, respectively), and estrus was monitored by visual estrus detection with the aid of an ESTROTECT estrous detection patches, and pregnancy was determined by transrectal ultrasonography. In experiment 1, there was a significant (P<0.01), quadratic relationship in expression of Na(+)/H(+) exchanger isoforms 1, 2, and 3 among animals that exhibited estrus, with expression greatest at time of CIDR removal, decreasing to the onset of estrus, and then increasing again following the onset of estrus. Among cows that did not exhibit estrus, the preceding relationship did not exist (P>0.46). In experiment 2, cows that had initiated estrus prior to fixed-time AI had decreased (P=0.01) uterine pH compared to cows that did not initiate estrus (6.78±0.03 and 6.89±0.03, respectively), and uterine pH at AI had an approximately linear effect on pregnancy success within the observed pH range. Furthermore, cows that initiated estrus prior to AI had increased (P=0.05) pregnancy success (52% vs. 38%) compared to cows that had not initiated estrus. In summary, expression of Na(+)/H(+) exchanger isoforms 1, 2, and 3 decreased after CIDR removal among cows that exhibited estrus, but did not change among cows that did not exhibit estrus. Additionally, as uterine pH decreased pregnancy success tended to increase (P=0.076, logistics regression). Thus, Na(+)/H(+) exchanger isoforms 1, 2, and 3 appear to be key regulators of uterine pH around the onset of estrus, and this change in uterine pH is critical for pregnancy success. Expression of Na(+)/H(+) exchanger isoforms 1, 2, and 3 decreased after CIDR removal among cows that exhibited estrus, but did not change among cows that did not exhibit estrus, and as uterine pH decreased, pregnancy success tended to increase. Copyright © 2016 Elsevier B.V. All rights reserved.

Tracking bacterial infection of macrophages using a novel red-emission pH sensor.

PubMed

Jin, Yuguang; Tian, Yanqing; Zhang, Weiwen; Jang, Sei-Hum; Jen, Alex K-Y; Meldrum, Deirdre R

2010-10-01

The relationship between bacteria and host phagocytic cells is key to the induction of immunity. To visualize and monitor bacterial infection, we developed a novel bacterial membrane permeable pH sensor for the noninvasive monitoring of bacterial entry into murine macrophages. The pH sensor was constructed using 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF) as an electron-withdrawing group and aniline as an electron-donating group. A piperazine moiety was used as the pH-sensitive group. Because of the strong electron-donating and -withdrawing units conjugated in the sensing moiety M, the fluorophore emitted in the red spectral window, away from the autofluorescence regions of the bacteria. Following the engulfment of sensor-labeled bacteria by macrophages and their subsequent merger with host lysosomes, the resulting low-pH environment enhances the fluorescence intensity of the pH sensors inside the bacteria. Time-lapse analysis of the fluorescent intensity suggested significant heterogeneity of bacterial uptake among macrophages. In addition, qRT-PCR analysis of the bacterial 16 S rRNA gene expression within single macrophage cells suggested that the 16 S rRNA of the bacteria was still intact 120 min after they had been engulfed by macrophages. A toxicity assay showed that the pH sensor has no cytotoxicity towards either E. coli or murine macrophages. The sensor shows good repeatability, a long lifetime, and a fast response to pH changes, and can be used for a variety of bacteria.

Field site leaching from recycled concrete aggregates applied as sub-base material in road construction.

PubMed

Engelsen, Christian J; Wibetoe, Grethe; van der Sloot, Hans A; Lund, Walter; Petkovic, Gordana

2012-06-15

The release of major and trace elements from recycled concrete aggregates used in an asphalt covered road sub-base has been monitored for more than 4 years. A similar test field without an asphalt cover, directly exposed to air and rain, and an asphalt covered reference field with natural aggregates in the sub-base were also included in the study. It was found that the pH of the infiltration water from the road sub-base with asphalt covered concrete aggregates decreased from 12.6 to below pH 10 after 2.5 years of exposure, whereas this pH was reached within only one year for the uncovered field. Vertical temperature profiles established for the sub-base, could explain the measured infiltration during parts of the winter season. When the release of major and trace elements as function of field pH was compared with pH dependent release data measured in the laboratory, some similar pH trends were found. The field concentrations of Cd, Ni, Pb and Zn were found to be low throughout the monitoring period. During two of the winter seasons, a concentration increase of Cr and Mo was observed, possibly due to the use of de-icing salt. The concentrations of the trace constituents did not exceed Norwegian acceptance criteria for ground water and surface water Class II. Copyright © 2012 Elsevier B.V. All rights reserved.

Super-Sensitive and Robust Biosensors from Supported Polymer Bilayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paxton, Walter F.

2015-09-01

Biological organisms are potentially the most sensitive and selective biological detection systems known, yet we are currently severely limited in our ability to exploit biological interactions in sensory devices, due in part to the limited stability of biological systems and derived materials. This proposal addresses an important aspect of integrating biological sensory materials in a solid state device. If successful, such technology could enable entirely new classes of robust biosensors that could be miniaturized and deployed in the field. The critical aims of the proposed work were 1) the calibration of a more versatile approach to measuring pH, 2) themore » use of this method to monitor pH changes caused by the light-induced pumping of protons across vesicles with bacteriorhodopsin integrated into the membranes (either polymer or lipid); 3) the preparation of bilayer assemblies on platinum surfaces; 4) the enhanced detection of lightinduced pH changes driven by bR-loaded supported bilayers. I have developed a methodology that may enable that at interfaces and developed a methodology to characterize the functionality of bilayer membranes with reconstituted membrane proteins. The integrity of the supported bilayer films however must be optimized prior to the full realization of the work originally envisioned in the original proposal. Nevertheless, the work performed on this project and the encouraging results it has produced has demonstrated that these goals are challenging yet within reach.« less

A more acceptable endoluminal implantation for remotely monitoring ingestible sensors anchored to the stomach wall.

PubMed

Ohta, Hidetoshi; Izumi, Shintaro; Yoshimoto, Masahiko

2015-01-01

Several types of implant devices have been proposed and introduced into healthcare and telemedicine systems for monitoring physiological parameters, sometimes for very long periods of time. To our disappointment, most of the devices are implanted invasively and by surgery. We often have to surgically remove such devices after they have finished their mission or before the battery becomes worn out. Wearable devices have the possibility to become new modalities for monitoring vital parameters less-invasively. However, for round-the-clock monitoring of data from sensors over long periods of time, it would be better to put them inside the body to avoid causing inconvenience to patients in their daily lives. This study tested a less invasive endoluminal approach and innovative tools (developed during our research into therapeutic capsule endoscopy) for remotely anchoring ingestible sensors to the stomach wall. Preliminary investigations are also described about wireless communication (NFC, ZigBee, and Bluetooth) for low power consumption and inductive extracorporeal power feeding wirelessly to the circuits in a phantom lined with swine gastric mucosa. Electrocardiogram and pH were monitored and those parameters were successfully transmitted by wireless communication ICs to the Internet via a portable device.

Improvement of the Performance of an Electrocoagulation Process System Using Fuzzy Control of pH.

PubMed

Demirci, Yavuz; Pekel, Lutfiye Canan; Altinten, Ayla; Alpbaz, Mustafa

2015-12-01

The removal efficiencies of electrocoagulation (EC) systems are highly dependent on the initial value of pH. If an EC system has an acidic influent, the pH of the effluent increases during the treatment process; conversely, if such a system has an alkaline influent, the pH of the effluent decreases during the treatment process. Thus, changes in the pH of the wastewater affect the efficiency of the EC process. In this study, we investigated the dynamic effects of pH. To evaluate approaches for preventing increases in the pH of the system, the MATLAB/Simulink program was used to develop and evaluate an on-line computer-based system for pH control. The aim of this work was to study Proportional-Integral-Derivative (PID) control and fuzzy control of the pH of a real textile wastewater purification process using EC. The performances and dynamic behaviors of these two control systems were evaluated based on determinations of COD, colour, and turbidity removal efficiencies.

Investigation of pH and temperature on optical rotatory dispersion for noninvasive glucose monitoring

NASA Astrophysics Data System (ADS)

Baba, Justin S.; Meledeo, Adam; Cameron, B. D.; Cote, Gerard L.

2001-06-01

The widespread occurrence of diabetes mellitus and the severity of its associated complications necessitate the development of non-invasive blood glucose measurement devices in an attempt to improve treatment regimens and curb the complications associated with this disease. One method showing promise in this endeavor utilizes optical polarimetry to monitor blood glucose levels indirectly by measuring glucose rotation of polarized light, which is a direct indication of glucose concentration, in the aqueous humor of the eye. The presence of other optically active (chiral) components in the aqueous humor of the eye have the potential to confound the glucose measurement of optical rotation when using a single wavelength polarimeter. Thus, this has led to the recent investigation of multispectral polarimetric systems which have the potential to enable the removal of confounder contributions to the net observed optical rotation, therefore, increasing glucose specificity and reducing glucose prediction errors. Such polarimetric systems take advantage of the uniqueness in the rotation of polarized light, as a function of wavelength, by the chiral molecule of interest. This is commonly referred to as the optical rotatory dispersion (ORD) spectra of the chiral molecule. ORD characterization of the chiral molecules within the aqueous humor is necessary for determining the optimum number of wavelengths needed to reduce glucose prediction errors; however, this information is often only given at the sodium-D line (589 nm) in the literature. This report describes the system we designed and built to measure ORD spectra for glucose and for albumin, the main optical confounder within the aqueous humor, as well as our investigation of the effects of temperature and pH on these ORD spectra.

Stimulation of gastric bicarbonate secretion by an analog of thyrotropin-releasing hormone, YM-14673, in the rat.

PubMed

Takeuchi, K; Ueshima, K; Okabe, S

1991-03-01

The effects of YM-14673, a thyrotropin-releasing hormone analog, on gastric alkaline secretion were investigated in the anesthetized rat pretreated with omeprazole (60 mg/kg, intraperitoneally) by measuring the luminal pH, transmucosal PD and HCO3- output. The whole stomach was perfused at a flow rate of 0.7 ml/min with saline (pH 4.5) in the absence of acid secretion, the pH of the perfusate and PD were continuously monitored and the HCO3- output was measured as acid-neutralizing capacity by back-titration of the perfusate to pH 4.5. YM-14673, given intravenously at the doses (0.1-1 mg/kg) that stimulated acid secretion, increased the pH and HCO3- output in a dose-dependent fashion, but did not significantly affect the PD. Prostaglandin E2 (1 mg/kg) elevated the pH and HCO3- output with concomitant decrease in the PD, whereas carbachol (4 micrograms/kg), similar to YM-14673, produced an increase of the pH and HCO3- output with no change in the PD. The net HCO3- output (4.3 +/- 0.3 muEq) induced by 0.3 mg/kg of YM-14673 was about 60 and 150% of that induced by prostaglandin E2 and carbachol, respectively. The increased pH and HCO3- responses caused by YM-14673 were almost completely abolished by vagotomy, significantly inhibited by atropine (0.3 mg/kg, intravenously) and indomethacin (5 mg/kg, subcutaneously) but not affected by pirenzepine (1 mg/kg, intravenously). These results suggest that YM-14673, a thyrotropin-releasing hormone analog, produced vagally mediated HCO3- secretion in the rat stomach, and the mechanism may involve the cholinergic system, which is mediated with muscarinic M2 receptors and interacts with endogenous prostaglandins.

The effect of orally administered ranitidine and once-daily or twice-daily orally administered omeprazole on intragastric pH in cats.

PubMed

Šutalo, S; Ruetten, M; Hartnack, S; Reusch, C E; Kook, P H

2015-01-01

Gastric acid suppressants frequently are used in cats with acid-related gastric disorders. However, it is not known if these drugs effectively increase intragastric pH in cats. To examine the effects of PO administered ranitidine and omeprazole on intragastric pH in cats and to compare the efficacy of once-daily versus twice-daily dosage regimens for omeprazole. Eight domestic shorthair cats. Using a randomized 4-way cross-over design, cats were given enteric-coated omeprazole granules (1.1-1.3 mg/kg q24h and q12h), ranitidine (1.5-2.3 mg/kg q12h), and placebo. Intragastric pH was monitored continuously for 96 hours using the Bravo(™) system, starting on day 4 of treatment, followed by a median washout period of 12 days. Mean percentage of time pH was ≥3 and ≥4 was compared among groups using repeated measures ANOVA. Mean ± SD percentage of time intragastric pH was ≥3 and ≥4 was 67.0 ± 24.0% and 54.6 ± 26.4% for twice-daily omeprazole, 24.4 ± 22.8% and 16.8 ± 19.3% for once-daily omeprazole, 16.5 ± 9.0% and 9.6 ± 5.9% for ranitidine, and 9.4 ± 8.0% and 7.0 ± 6.6% for placebo administration. Twice-daily omeprazole treatment significantly increased intragastric pH, whereas pH after once-daily omeprazole and ranitidine treatments did not differ from that of placebo-treated cats. Only twice-daily PO administered omeprazole significantly suppressed gastric acidity in healthy cats, whereas once-daily omeprazole and standard dosages of ranitidine were not effective acid suppressants in cats. Copyright © 2015 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of American College of Veterinary Internal Medicine.

Integration and application of optical chemical sensors in microbioreactors.

PubMed

Gruber, Pia; Marques, Marco P C; Szita, Nicolas; Mayr, Torsten

2017-08-08

The quantification of key variables such as oxygen, pH, carbon dioxide, glucose, and temperature provides essential information for biological and biotechnological applications and their development. Microfluidic devices offer an opportunity to accelerate research and development in these areas due to their small scale, and the fine control over the microenvironment, provided that these key variables can be measured. Optical sensors are well-suited for this task. They offer non-invasive and non-destructive monitoring of the mentioned variables, and the establishment of time-course profiles without the need for sampling from the microfluidic devices. They can also be implemented in larger systems, facilitating cross-scale comparison of analytical data. This tutorial review presents an overview of the optical sensors and their technology, with a view to support current and potential new users in microfluidics and biotechnology in the implementation of such sensors. It introduces the benefits and challenges of sensor integration, including, their application for microbioreactors. Sensor formats, integration methods, device bonding options, and monitoring options are explained. Luminescent sensors for oxygen, pH, carbon dioxide, glucose and temperature are showcased. Areas where further development is needed are highlighted with the intent to guide future development efforts towards analytes for which reliable, stable, or easily integrated detection methods are not yet available.

High spatiotemporal resolution monitoring of hydrological function across degraded peatlands in the south west UK.

NASA Astrophysics Data System (ADS)

Ashe, Josie; Luscombe, David; Grand-Clement, Emilie; Gatis, Naomi; Anderson, Karen; Brazier, Richard

2014-05-01

The Exmoor/Dartmoor Mires Project is a peatland restoration programme focused on the geoclimatically marginal blanket bogs of South West England. In order to better understand the hydrological functioning of degraded/restored peatlands and support land management decisions across these uplands, this study is providing robust spatially distributed, hydrological monitoring at a high temporal resolution and in near real time. This paper presents the conceptual framework and experimental design for three hydrological monitoring arrays situated in headwater catchments dominated by eroding and drained blanket peatland. Over 250 individual measurements are collected at a high temporal resolution (15 minute time-step) via sensors integrated within a remote telemetry system. These are sent directly to a dedicated server over VHF and GPRS mobile networks. Sensors arrays are distributed at varying spatial scales throughout the studied catchments and record multiple parameters including: water table depth, channel flow, temperature, conductivity and pH measurements. A full suite of meteorological sensors and ten spatially distributed automatic flow based water samplers are also connected to the telemetry system and controlled remotely. This paper will highlight the challenges and solutions to obtaining these data in exceptionally remote and harsh field conditions over long (multi annual) temporal scales.

Efficiency of temporary storage of geothermal waters in a lake system: Monitoring the changes of water quality and bacterial community structures.

PubMed

Szirányi, Barbara; Krett, Gergely; Kosáros, Tünde; Janurik, Endre; Pekár, Ferenc; Márialigeti, Károly; Borsodi, Andrea K

2017-12-01

Disposal of used geothermal waters in Hungary often means temporary storage in reservoir lakes to reduce temperature and improve water quality. In this study, the physical and chemical properties and changes in the bacterial community structure of a reservoir lake system in southeast region of Hungary were monitored and compared through 2 years, respectively. The values of biological oxygen demand, concentrations of ammonium ion, total inorganic nitrogen, total phosphorous, and total phenol decreased, whereas oxygen saturation, total organic nitrogen, pH, and conductivity increased during the storage period. Bacterial community structure of water and sediment samples was compared by denaturing gradient gel electrophoresis (DGGE) following the amplification of the 16S rRNA gene. According to the DGGE patterns, greater seasonal than spatial differences of bacterial communities were revealed in both water and sediment of the lakes. Representatives of the genera Arthrospira and Anabaenopsis (cyanobacteria) were identified as permanent and dominant members of the bacterial communities.

Monitoring of Water Spectral Pattern Reveals Differences in Probiotics Growth When Used for Rapid Bacteria Selection.

PubMed

Slavchev, Aleksandar; Kovacs, Zoltan; Koshiba, Haruki; Nagai, Airi; Bázár, György; Krastanov, Albert; Kubota, Yousuke; Tsenkova, Roumiana

2015-01-01

Development of efficient screening method coupled with cell functionality evaluation is highly needed in contemporary microbiology. The presented novel concept and fast non-destructive method brings in to play the water spectral pattern of the solution as a molecular fingerprint of the cell culture system. To elucidate the concept, NIR spectroscopy with Aquaphotomics were applied to monitor the growth of sixteen Lactobacillus bulgaricus one Lactobacillus pentosus and one Lactobacillus gasseri bacteria strains. Their growth rate, maximal optical density, low pH and bile tolerances were measured and further used as a reference data for analysis of the simultaneously acquired spectral data. The acquired spectral data in the region of 1100-1850nm was subjected to various multivariate data analyses - PCA, OPLS-DA, PLSR. The results showed high accuracy of bacteria strains classification according to their probiotic strength. Most informative spectral fingerprints covered the first overtone of water, emphasizing the relation of water molecular system to cell functionality.

PRELIMINARY DATA REPORT: HUMATE INJECTION AS AN ENHANCED ATTENUATION METHOD AT THE F-AREA SEEPAGE BASINS, SAVANNAH RIVER SITE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Millings, M.

2013-09-16

A field test of a humate technology for uranium and I-129 remediation was conducted at the F-Area Field Research Site as part of the Attenuation-Based Remedies for the Subsurface Applied Field Research Initiative (ABRS AFRI) funded by the DOE Office of Soil and Groundwater Remediation. Previous studies have shown that humic acid sorbed to sediments strongly binds uranium at mildly acidic pH and potentially binds iodine-129 (I-129). Use of humate could be applicable for contaminant stabilization at a wide variety of DOE sites however pilot field-scale tests and optimization of this technology are required to move this technical approach frommore » basic science to actual field deployment and regulatory acceptance. The groundwater plume at the F-Area Field Research Site contains a large number of contaminants, the most important from a risk perspective being strontium-90 (Sr-90), uranium isotopes, I-129, tritium, and nitrate. Groundwater remains acidic, with pH as low as 3.2 near the basins and increasing to the background pH of approximately 5at the plume fringes. The field test was conducted in monitoring well FOB 16D, which historically has shown low pH and elevated concentrations of Sr-90, uranium, I-129 and tritium. The field test included three months of baseline monitoring followed by injection of a potassium humate solution and approximately four and half months of post monitoring. Samples were collected and analyzed for numerous constituents but the focus was on attenuation of uranium, Sr-90, and I-129. This report provides background information, methodology, and preliminary field results for a humate field test. Results from the field monitoring show that most of the excess humate (i.e., humate that did not sorb to the sediments) has flushed through the surrounding formation. Furthermore, the data indicate that the test was successful in loading a band of sediment surrounding the injection point to a point where pH could return to near normal during the study timeframe. Future work will involve a final report, which will include data trends, correlations and interpretations of laboratory data.« less

Non-erosive and uncomplicated erosive reflux diseases: Difference in physiopathological and symptom pattern

PubMed Central

Bresadola, Vittorio; Adani, Gian Luigi; Londero, Francesco; Leo, Cosimo Alex; Cherchi, Vittorio; Lorenzin, Dario; Rossetto, Anna; Vit, Gianmatteo; Baccarani, Umberto; Terrosu, Giovanni; Anna, Dino De

2011-01-01

AIM: To investigate differences in the physiopathological findings (manometry and pH monitoring) and symptoms between cases of non-erosive reflux disease (NERD) and erosive reflux disease (ERD) found positive at 24 h pH monitoring. METHODS: For a total of 670 patients who underwent 24 h pH monitoring, esophageal manometry and upper endoscopy were retrospectively evaluated, assessing the reflux symptoms, manometric characteristics of the lower esophageal sphincter (LES) and esophageal body and the presence or absence of esophagitis and hiatal hernia. Typical and atypical symptoms were also evaluated. For inclusion in the study, patients had to have NERD or ERD and be found positive on pH monitoring (NERD+). Patients with Gastroesophageal reflux disease (GERD) complicated by stenosis, ulcers or Barrett's esophagus were ruled out. RESULTS: 214 patients were involved in the study, i.e. 107 cases of NERD+ and 107 of ERD. There were no significant gender- or age-related differences between the two groups. The ERD group had more cases of hiatal hernia (P = 0.02) and more acid reflux, both in terms of number of reflux episodes (P = 0.01) and as a percentage of the total time with a pH < 4 (P = 0.00), when upright (P = 0.007) and supine (P = 0.00). The NERD+ cases had more reflux episodes while upright (P = 0.02) and the ERD cases while supine (P = 0.01). The LES pressure was higher in cases of NERD+ (P = 0.03) while the amplitude and duration of their esophageal peristaltic waves tended to be better than in the ERD group (P >0.05). The NERD+ patients presented more often with atypical symptoms (P = 0.01). CONCLUSION: The NERD+ patients’ fewer reflux episodes and the fact that they occurred mainly while in the upright position (unlike the cases of ERD) may be two factors that do not favor the onset of esophagitis. The frequently atypical symptoms seen in patients with NERD+ need to be accurately evaluated for therapeutic purposes because patients with GERD and atypical symptoms generally respond only partially to medical and surgical treatments. PMID:21860835

Experiences and recommendations in deploying a real-time, water quality monitoring system

NASA Astrophysics Data System (ADS)

O'Flynn, B.; Regan, F.; Lawlor, A.; Wallace, J.; Torres, J.; O'Mathuna, C.

2010-12-01

Monitoring of water quality at a river basin level to meet the requirements of the Water Framework Directive (WFD) using conventional sampling and laboratory-based techniques poses a significant financial burden. Wireless sensing systems offer the potential to reduce these costs considerably, as well as provide more useful, continuous monitoring capabilities by giving an accurate idea of the changing environmental and water quality in real time. It is unlikely that the traditional spot/grab sampling will provide a reasonable estimate of the true maximum and/or mean concentration for a particular physicochemical variable in a water body with marked temporal variability. When persistent fluctuations occur, it is likely only to be detected through continuous measurements, which have the capability of detecting sporadic peaks of concentration. Thus, in situ sensors capable of continuous sampling of parameters required under the WFD would therefore provide more up-to-date information, cut monitoring costs and provide better coverage representing long-term trends in fluctuations of pollutant concentrations. DEPLOY is a technology demonstration project, which began planning and station selection and design in August 2008 aiming to show how state-of-the-art technology could be implemented for cost-effective, continuous and real-time monitoring of a river catchment. The DEPLOY project is seen as an important building block in the realization of a wide area autonomous network of sensors capable of monitoring the spatial and temporal distribution of important water quality and environmental target parameters. The demonstration sites chosen are based in the River Lee, which flows through Ireland's second largest city, Cork, and were designed to include monitoring stations in five zones considered typical of significant river systems--these monitor water quality parameters such as pH, temperature, depth, conductivity, turbidity and dissolved oxygen. Over one million data points have been collected since the multi-sensor system was deployed in May 2009. Extreme meteorological events have occurred during the period of deployment and the collection of real-time water quality data as well as the knowledge, experience and recommendations for future deployments are discussed.

Development of an extended-range fiber optic pH sensor using evanescent wave absorption of sol-gel-entrapped pH indicators

NASA Astrophysics Data System (ADS)

Butler, Thomas M.; MacCraith, Brian D.; McDonagh, Colette M.

1995-09-01

The sol-gel process has been used to entrap pH indicators in porous glass coatings for sensor applications. This sensor is based on evanescent wave absorption using an unclad optical fiber dipcoated with the pH sensitive coating. The entrapped pH indicators show a broadening of the pH range with respect to the behavior in solution giving accurate measurement over three pH units when one indicator is used (bromophenol blue) and over six pH units (pH 3-9) when two indicators are used (bromophenol blue and bromocresol purple). The response of the pH sensor was monitored by measuring absorption at 590 nm referenced against a nonabsorbing region of the spectrum. This enabled the use of LED sources together with low cost photodiodes. The sensor displayed short response time and good repeatability. The thickness and stability of the pH sensitive coatings can be influenced by modifying the composition of the starting sol mixture. The evanescent absorption, and hence the sensitivity of the sensor, can be increased by selectively launching higher order modes in the fiber. These issues together with a full sensor characterization will be reported.