Abstract: The P(r) to P(fr) transition of recombinant Synechocystis PCC 6803 phytochrome Cph1 and its N-terminal sensor domain Cph1Delta2 is accompanied by net acidification in unbuffered solution. The extent of this net photoreversible proton release was measured with a conventional pH electrode and increased from less than 0.1 proton released per P(fr) formed at pH 9 to between 0.6 (Cph1) and 1.1 (Cph1Delta2) H(+)/P(fr) at pH 6. The kinetics of the proton release were monitored at pH 7 and pH 8 using flash-induced transient absorption measurements with the pH indicator dye fluorescein. Proton release occurs with time constants of approximately 4 and approximately 20 ms that were also observed in parallel measurements of the photocycle (tau(3) and tau(4)). The number of transiently released protons per P(fr) formed is about one. This H(+) release phase is followed by a proton uptake phase of a smaller amplitude that has a time constant of approximately 270 ms (tau(5)) and is synchronous with the formation of P(fr). The acidification observed in the P(r) to P(fr) transition with pH electrodes is the net effect of these two sequential protonation changes. Flash-induced transient absorption measurements were carried out with Cph1 and Cph1Delta2 at pH 7 and pH 8. Global analysis indicated the presence of five kinetic components (tau(1)-tau(5): 5 and 300 micros and 3, 30, and 300 ms). Whereas the time constants were approximately pH independent, the corresponding amplitude spectra (B(1), B(3), and B(5)) showed significant pH dependence. Measurements of the P(r)/P(fr) photoequilibrium indicated that it is pH independent in the range of 6.5-9.0. Analysis of the pH dependence of the absorption spectra from 6.5 to 9.0 suggested that the phycocyanobilin chromophore deprotonates at alkaline pH in both P(r) and P(fr) with an approximate pK(a) of 9.5. The protonation state of the chromophore at neutral pH is therefore the same in both P(r) and P(fr). The light-induced deprotonation and reprotonation of Cph1 at neutral pH are thus due to pK(a) changes in the protein moiety, which are linked to conformational transitions occurring around 4 and 270 ms after photoexcitation. These transient structural changes may be relevant for signal transduction by this cyanobacterial phytochrome.

Abstract: Soil pH often is measured in samples from the bottoms of aquaculture ponds. Several different techniques for soil pH are used. This study considered the differences in pH obtained by the different methods and determined which methods appeared most useful. Dual electrodes (indicating and reference) and a single-probe combination electrode gave similar pH values when inserted into 1:1 mixtures of dry soil and distilled water. There were slight differences in pH between readings with dual and combination electrodes when the dual electrodes were arranged with the indicating electrode in the sediment phase and the reference electrode in the supernatant phase of the mixture. The two-phase method with the dual electrode does not appear warranted because of greater difficulty in making measurements. Dry soil: distilled water ratios of 1:2.5, 1:5, and 1:10 had progressively greater pH readings than obtained at a 1:1 ratio. Measurements made in 0.01 M CaCl2 and 1.0 M KCl had much different values than those made in distilled water. Higher pH resulted when pH was measured without stirring or in filtrates of soil-water mixtures. A 20-min period of intermittent stirring before making measurements was necessary for a stable pH value. Particle size did not influence pH in aliquots passing 0.053 to 2.36-mm sieves. Drying temperature had a strong influence on pH, and measurements made on samples dried at 40 to 60 C are probably most reliable. Measurements of in situ pH in wet soil with standard pH electrode or a portable acidity tester differed greatly from those made in 1:1 dry soil to distilled water mixtures. Pond bottom soil pH measurement should be standardized. Based on findings of this study, the following method is suggested: dry soil at 60 C in a forced-draft oven; pulverize soil to pass a 2-mm sieve; mix soil and distilled water in a 1:1 ratio (weight: volume); stir intermittently with glass rod for 30 min; insert dual electrodes or a combination electrode into the mixture; measure pH while stirring.

Abstract: Background/aims: Measurement of skin surface pH is used in clinical research to evaluate hazardous shifts in pH following external exposures and to evaluate the state of diseased skin with acute or chronic changes. It is therefore important to measure skin surface pH as precisely as possible. The aim of this study was to compare two commercially available pH meters used for skin surface pH measurement, to reveal differences between them in measured skin pH on the forearm. Methods: The first pH meter (pH900) had a pointed electrode and a stabilisation period of 3 s. The second pH meter (pH meter 1140) had a circular electrode and no fixed stabilisation period. Twelve healthy subjects (6 male and 6 female Caucasians) entered the study. The pH measurements were performed once an hour from 8 a.m. to 3 p.m. on both forearms in five areas from the elbow to the “wristwatch” zone. In each area, three measurements were performed next to each other with both pH meters (15 measurements per arm per hour per pH meter). Results: The pH900 has a higher measuring level and a higher variation than the pH meter 1140. Conclusion: A skin surface pH meter with a circular electrode and with no fixed stabilisation period is preferable. It is recommended that the pH meter be allowed to stabilise for at least 7 s before the result is read.

Abstract: The conduit tube 3 and the conduit tube 4 to flow the carrier solution to the gas exchanger 7 are provided, and in the conduit tube 3 , the reference pH electrode 14 is provided, and in the conduit tube 4 , the measuring pH electrode 16 is provided, both pH electrodes preferably being chosen of the ISFET type (Ion-Sensitive Field-Effect-Transistor). The gas exchanger 7 is partitioned from the outside by the gas permeable membrane 6 . Initially, the gas exchange section 1 is inserted into the test substance, and next, the carrier solution is flowed at the speed of a degree in which the gas exchange is not conducted in the gas exchanger 7 . The output potential difference ΔV(0) between the reference pH electrode 14 and the measuring pH electrode 16 at this time, is found. Next, the carrier solution is slowly flowed at a predetermined speed, so that the gas exchange is fully conducted in the gas exchanger 7 , the output potential difference ΔV(t) between the reference pH electrode 14 and the measuring pH electrode 16 at time t is found, and the difference ΔΔV(t) between the ΔV(t) measured at this time and the ΔV(0)obtained at the last time, is obtained. This value corresponds to the correct gas partial pressure change.

Abstract: The aim of this study was to compare the pH changes in the dental plaque after rinsing with sugared- (sucrose) or sugar-free (saccharine, cyclamate and sorbitol) versions of the same pediatric acetaminophen solution (ekosetol) up to one hour Twenty-nine undergraduate dental students (17 girls and 12 boys) collected plaque for 48 hours by abstaining from oral hygiene, during which period they maintained normal dietary habits Plaque sampling was done in two subsequent days before and 2, 5, 10, 15, 20, 25, 30, 40, 50 and 60 minutes after rinsing with both solutions Measurements of pH were done within one hour using a micro pH electrode and a pH meter All experiments were finished in 6 days by dividing the group to three Results showed a significant difference between groups in respect to pH values and pH drops after rinsing Mean pH values were below 570 for one hour in sugared solution, whereas no mean pH value was detected below 580 for one hour with the sugar-free solution Minimum pH values (sugar-free: 562+/-036; sugared: 500+/-033, p<0001) and maximum pH drops (sugar-free: -057+/-026; sugared: -116+/-044, p<0001) were also significantly different No difference was found between genders We concluded that changing of sucrose to non-acidogenic sweeteners was essential to prevent the cariogenic potential of the pediatric medicines

Abstract: The performance of a sensing module for pO2, pCO2, and pH was tested from a practical point of view and its design was modified for the pO2 electrode and the pH combination electrode. Owing to the elongated lifetime of the on-chip liquid-junction reference electrode, pH measurement could be conducted repeatedly. The outputs from these electrodes taken in a 4.6 μl flow channel on the chip and in a 100 ml beaker were compared. Although a substantial difference was observed between the measured currents of the pO2 electrode with a 0.2 mm ×1.2 mm cathode, the difference was reduced markedly by using a 25 μm ×25 μm cathode. A good coincidence was observed between the values of potential obtained with the pH electrode, while the data with the pCO2 electrode suggested that it needed a substantial modification of design depending upon its applications. The sensing module was actually used to measure blood gas levels in whole human blood and the values were compared with those obtained by a commercial blood gas analyzer. The deviation of pH values was within 0.06 pH units and pO2 values were within an acceptable level. However, substantial deviations of pCO2 values were observed.

Abstract: This work confirms that the activities of individual ions measured with ion-selective electrodes are physically meaningful. The individual activities of the Cl - , Na + and K + ions in single-electrolyte aqueous solutions of HCl, NaOH and KOH were measured at 298.2 K in the range from 0 to 2 molal. In the pH range from 1 to 13, the pH values calculated from the measured activities of the ions are in good agreement with the values obtained with a pH probe. In agreement with previous results for potassium ions, and opposite to the behavior of other cations in 1:1 electrolyte solutions, the K + and the H + ions were found to have smaller activities than their conjugate anions. The experimental activity coefficients of the ions were correlated with the Khoshkbarchi-Vera equation and with the New Hydration Theory, and compared with the predictions given by the Pitzer theory.

Abstract: The accuracy of a portable pH meter in measuring blood pH in neonatal calves, urine pH, and ruminal fluid pH in cows has been assessed Thirty-five diarrheic and 15 healthy beef calves were used for blood gas analysis; 57 healthy dairy cows provided voided urine samples; and ruminal fluid samples were obtained from 10 dairy cows with ruminal fistulas on 4 separate days Measurements of blood pH were obtained from an automated blood gas analyzer and the portable pH meter Measurements of urine and ruminal fluid pH were determined with the benchtop pH meter, urinalysis strips, narrow range pH paper, and the portable pH meter The portable pH meter was more accurate in measuring urine pH and ruminal fluid pH in cows than blood pH in neonatal calves The urinalysis strips and the narrow range pH paper were found adequate to evaluate urine and ruminal pH

Abstract: The present invention presents a particle-size distribution measuring apparatus which allows measuring simultaneously the dispersion state of particles in suspension medium and the particle-size distribution of the particles. The present invention is a particle-size distribution measuring apparatus which measures the particle-size distribution of particles included in a sample. The particle-size distribution measuring apparatus comprises a pH meter for measuring the pH value of the sample and an information processing portion which determines the relation between the pH value and the particle-size distribution on the basis that the pH value measured by the pH meter and the measured particle-size distribution are in the same state.

Abstract: To obtain glass membrane electrodes selective for anions and metal ions, pH electrode glass membranes were modified by a sol−gel method using a quaternary ammonium salt and a bis(crown ether). A chloride ion-sensing glass membrane was designed, in which a pH electrode glass membrane was modified chemically by an alkoxysilyl quaternary ammonium chloride. X-ray photoelectron spectroscopy confirmed the chemical bonding of the quaternary ammonium moiety to the starting glass surface, which afforded the first example of glass-based “anion”-sensing membranes. A neutral carrier-type sodium ion-selective glass membrane was also fabricated which encapsulates a bis(12−crown−4) derivative in its sol−gel-derived surface. Both sol−gel-modified anion and metal ion-selective glass electrodes exhibited high sensitivity to their ion activity changes. The present sol−gel modification paves the way for designing glass-based ion sensors with tailor-made ion selectivities toward anions as well as cations.

Abstract: PROBLEM TO BE SOLVED: To provide a water treatment apparatus and a water treatment method which enables easy and proper control of supply quantity of chlorine for disinfection with respect to water to be treated SOLUTION: Electrodes 11, 12, electrodes 13, 14 and electrodes 15, 16 in a treated water tank 10 respectively constitute a pair of electrodes and electric power is supplied from an electric source 51 thereto A controller 50 controls the operation of the electric source 51 and, thereby, electric power supplied to the respective pairs of electrodes and a quantity of current flowing between the electrodes are controlled The controller 50 calculates the difference between oxidation-reduction potentials measured by a second ORP (oxidation-reduction potential) meter 31 and a first ORP meter 21 Then, the value of the difference is compared with the reference value which differs in accordance with PH value of water to be treated measured by a PH meter 60 and, based on the comparison result, the value of current flowing between the respective pairs of electrodes is controlled COPYRIGHT: (C)2003,JPO

Abstract: PROBLEM TO BE SOLVED: To provide a control method capable of stabilizing denitration efficiency at a high efficiency by precisely keeping the thiosulfate concentration of an absorption solution in a first and a second stage absorption units at a specified concentration and capable of reducing chemicals cost by using an appropriate amount of chemicals. SOLUTION: In a thiosulfate denitration method employing two stage series absorption units, a method of controlling concentration of an absorption solution in the thiosulfate denitration method is characterized in that an oxidation reduction potentiometer and a pH meter are provided in a first stage absorption unit, a pH meter is provided in a second stage absorption unit, the supply amount of a second stage absorption solution to be supplied to the first stage absorption unit is controlled on the basis of potential value measured by the oxidation reduction potential meter of the first stage absorption unit, the supply amount of an alkali solution to be supplied to the first stage absorption unit is controlled on the basis of pH value measured by the pH meter of the first stage absorption unit, and the supply amount of the alkali solution and the supply amount of the thiosulfate solution to be supplied to the second stage absorption unit are controlled on the basis of pH value measured by the pH meter of the second stage absorption unit.

Abstract: PROBLEM TO BE SOLVED: To provide an inexpensive decoloring technique for colored wastewater by utilizing a simple method using sulfur SOLUTION: Inflow water is introduced into a reaction tank 1, which houses a filter medium 2 filled with sulfur or a mixed particulate material of sulfur and calcium carbonate, after the pH thereof is adjusted to 8-9 or as it is Air is passed through a filler comprising the mixed particulate material of sulfur and calcium carbonate in an ascending flow state at least under a condition of 10 m /m min so as to directly come into contact with the filler to bring about aerobic sulfur oxidizing condition due to sulfur oxidizing bacteria under an aerobic condition and a color component is oxidized and decomposed to be decolored A pH meter 8 and a stirrer 9 are provided in order to adjust the pH of inflow water in this apparatus and a pH adjusting tank 7 is further provided through a storage tank 10 and a supply pipe 11 so as to automatically supply an acid or alkali to adjust the inflow water to predetermined pH Decolored discharge water 5 is discharged after adjusted in pH if necessary

Abstract: An electrochemical sensor for detecting the presence and amount of acetate in cell culture and fermentation media. The electrochemical sensor has a pH electrode, an internal reference electrode, a special high-tensile strength gas permeable membrane, and internal reference electrolyte such that acetate concentration can be measured using a pre-treatment buffer having a pH of about 5.5.

Abstract: PROBLEM TO BE SOLVED: To achieve reliable measurement with a simple configuration and at the same time eliminate the need for maintaining a reference electrode by using an ion-selective electrode that selectively responds to ion species existing in reaction liquid by a fixed amount as the reference electrode. SOLUTION: An electrochemical detector 1 used, for example, for liquid chromatography is provided with, for example, a reference pH electrode 32. The electrode 32 is composed by forming a pH-sensitive film that is made of iridium oxide where the ratio of oxygen to iridium is within a specific range on a sensitive film support being fixed, for example, on the end face of a holder 31. While a liquid-contacting part with the reaction liquid of the pH-sensitive film is left, the sensitive film support is covered with an insulation film, and a porous insulation film preferably with a specific hole diameter is deposited on the liquid-contacting part of the pH-sensitive film. As the reference electrode, a sodium ion electrode, a lithium ion electrode, a potassium ion electrode, a nitrogen ion electrode, a nitric acid ion electrode, or the like can be used and is composed by each specific sensitive film.

Abstract: PROBLEM TO BE SOLVED: To control the injection of carbonate in a water treatment installation with high accuracy at a low running cost SOLUTION: A pH meter 5 for measuring the pH of water to be treated in a reaction tank l and a sodium carbonate injection pump 7 for injecting sodium carbonate in the reaction tank 1 from a sodium carbonate storage tank 8 are arranged to the reaction tank 1 The measured value of the pH meter 5 is inputted to an injection control device 6 to be converted to an electric signal which is, in turn, outputted to the sodium carbonate injection pump 7 to control the injection amount of sodium carbonate The optimum value of the pH in the reaction tank 1 is preset to the injection amount control device 6 and the sodium carbonate injection pump 7 is controlled so that the pH in the reaction tank 1 approaches the optimum value

Abstract: A pH electrode having a pH-sensitive region on an electrically conductive support, said pH-sensitive region comprising a mixture of between 50% and 85% of the total mixture by weight of particles of a Group VA or Group VIII metal incorporated in, or applied to, a polymer substrate of a non-shrinking plastic selected from polyimides, the polymer substrate having a resistivity of 10 to 100 Kohms/square the metal particles including antimony particles and, when said particles are incorporated into said resistive polymer substrate, having said pH-sensitive region abraded to expose said particles.

Abstract: The utility model relates to an anode bed sodium ion concentration detector, comprising a flow regulator, a water sample alkalization box, a detecting cup, a PNa electrode, a composite pH electrode, and a display. The utility model not only overcomes the deficiency of alkalization, but also avoids the excess of the alkalization. No matter how the pH value of water samples to change, the ph can be regulated within the optimum range. The utility model can automatically feed amine and do quantitative alkalization for the water samples. In addition, by a connecting pipeline arranged on an inner wall of the detecting cup, the anode bed sodium ion concentration detector makes the product structure be simple, compact, and delicate.

Abstract: The pH electrode is an very precise detection element,and its sensitivity and stability will decrease after being contaminated.Some methods to clean pH electrode are introduced,such as ultrasonic cleaning,mechanical cleaning,water jet cleaning,chemical solution jet cleaning,compressed air jet cleaning,composite cleaning,manual cleaning,and so on.Methods to clean the ceramic core inside the electrode are also introduced.This paper can give some references to pratical production.

Abstract: A method for separating a hydroxide ion, characterized in that a hydroxide ion (OH-) in an aqueous solution is separated by a chromatograph. The method allows the separation and the measurement with high precision of a hydroxide ion which has not been achieved by a conventional pH titration method and pH meter method, and further allows the selective extraction and concentration thereof.

Abstract: Planar PVC film plasticized with pH sensitizing carrier N, N'-dicapryl octadecanoylamide is adhered to one end of PVC electrode casing and one inner reference Ag/AgCl electrode is soaked in solution of buffering phosphate containing 0.01 M NaCl. When used, one outer reference electrode is connected through a salt bridge. The present invention is superior in that the plastic PVC electrode film is less likely to be damaged, is low in resistance and non-corrosive by hydrofluoric acid.

Abstract: The on line pH measurement of liquor has been applied abroad in the department of the electric power and the chemistry.It is an important parameter to scale the acidity and basicity of liquor.Through the on-line continual pH measurement,the acidity and basicity of water can be controlled within a preconcerted range and the erodation and the fabrication of the instrument are depreciated.But the temperature is the major factor to affect the measurement accuracy.To deduce the error,in this article,according to the character of the double function and small volume of semiconductor refrigeration and we put a pH pole in the small constant temperature system.By this means the fluctuation of temperature will be faint,so the measurement accuracy of the instrument is improved.

Abstract: The article contains sections titled: 1. Introduction 1.1. Historical Background 1.2. Buffer Solutions 1.3. Activities 1.4. Self-Dissociation 1.5. Importance of pH Measurements 2. pH Scales 2.1. Indicators 2.2. Electrochemical Methods 2.3. Primary pH Standards 2.4. Secondary pH Standard Solutions 3. Electrode Cells 3.1. Glass Electrodes 3.2. Reference Electrodes 3.3. Liquid Junctions 3.4. Combined Electrodes 3.5. Testing Glass Electrode Cells 3.6. Alternative pH Electrodes 4. pH Meters or Transformers 4.1. Input Amplifier 4.2. Correction Functions 4.3. Output 4.4. Microprocessor-Controlled pH Meters 4.5. Testing pH Meters 4.6. Self Monitoring 4.7. Self Calibration 5. Analytical Applications 5.1. Calibration of Glass Electrode Cells 5.2. pH Measurement in Water Analysis 5.3. pH Measurement in Concentrated Solutions 5.4. Suspension Effects 5.5. pH Measurement in Nonaqueous Solvents 6. Technical pH Measurements 6.1. Extreme Conditions 6.2. Installation 6.3. Electrode Assemblies 6.4. Pressure Control 6.5. Retractable Assemblies 7. pH Control