Search

In this paper, we propose a tilted fiber Bragg grating (TFBG) pH sensor based on polyaniline (PANI) reactive deposition film. The micron-scale thickness polyaniline film provides the sensor with good sensitivity, and it achieves measurement of pH values ranging from 2 to 12 by utilizing the pH-responsive mechanism of PANI and the refractive index characteristics of TFBG. Experimental results show that within the 2–12 pH range, the sensitivity of the TFBG surface plasmon resonance pH sensor based on PANI coating is − 0.03815, and results demonstrate, a linear correlation coefficient between wavelength and pH value reaching 0.98719. This indicates significant potential for future engineering applications in real-world pH measurement using this sensor. [ABSTRACT FROM AUTHOR]

Background: Preterm infants require the use of nasogastric and orogastric enteral access devices (EADs) to provide nutrition and medications. Confirmation of the location of the tip of the EAD is essential to minimize complications. At the study site, EAD location was limited to verifying the centimeter marking at the lip/nares and nonevidence-based methods of visual observation of aspirate and auscultation. Purpose: Implement an evidenced-based EAD placement confirmation protocol, and by 90 days post-education and implementation, achieve adherence of 90%. Methods: This quality improvement project implemented a nurse-driven evidence-based protocol for EAD verification. The intervention was based on the New Opportunities for Verification of Enteral Tube Location best practice recommendations. Prior to implementation, education sessions focused on insertion measurement technique and gastric pH measurement. Radiographs, insertion measurement technique, centimeter marking, and gastric pH measurement were used for EAD location confirmation. To determine compliance with the protocol, audits were conducted and questionnaires assessing current practice regarding EAD confirmation were administered pre- and postimplementation. Results: The protocol increased nursing knowledge regarding evidence-based EAD insertion and verification procedures, incorporated pH measurement into practice, and reduced use of auscultation for confirmation. Nursing adherence to the protocol was 92%. Implications for Practice and Research: This provides a model for how to successfully implement and achieve adherence to an evidence-based EAD placement confirmation nurse-driven protocol. Further research is needed to verify the effectiveness of the protocol and establish consensus on approaches specifically for the neonatal population. [ABSTRACT FROM AUTHOR]

A new construction of a potentiometric sensor was introduced for the first time. It relies on the use of two membranes instead of one, as in the well-known coated-disc electrode. For this purpose, a new electrode body was constructed, including not one, but two glassy carbon discs covered with an ion-selective membrane. This solution allows for the sensor properties to be enhanced without using additional materials (layers or additives) on the membrane. The new construction is particularly useful for in situ measurements in environmental samples. Two ion-selective polymeric membranes were used, namely H+ and K+-selective membranes, to confirm the universality of the idea. The tests conducted included chronopotentiometric tests, electrochemical impedance spectroscopy, and potentiometric measurements. The electrical and analytical parameters of the sensors were evaluated and compared for all tested electrodes to evaluate the properties of the planar electrode versus previously known constructions. Research has shown that the application of two membranes instead of one allows for the resistance of an electrode to be lowered and for the electrical capacitance to be elevated. Improving the electrical properties of an electrode resulted in the enhancement of its analytical properties. The pH measurement range of the planar electrode is 2–11, which is much wider in contrast to that of the single-membrane electrode. The linear range of the K+-selective planar electrode is wider than that of the coated-disc electrode and equals 10−6 to 10−1 M. The response time turned out to be a few seconds shorter, and the potential drift was smaller due to the application of an additional membrane in the electrode construction. This research creates a new opportunity to design robust potentiometric sensors, as the presented construction is universal and can be used to obtain electrodes selective to various ions. [ABSTRACT FROM AUTHOR]

Nitrogen-doped carbon quantum dots (N-doped CQDs) were prepared using a one-step sintering technique, with ammonium citrate as the precursor. These were compared to carbon quantum dots (CQDs) synthesized from citric acid. A range of characterization techniques, including x-ray diffraction analysis (XRD), raman spectroscopy, transmission electron microscopes (TEM), x-ray photoelectron spectroscopy (XPS), ultraviolet–visible absorption spectroscopy (UV–Vis absorption spectra), and fourier transform infrared spectroscopy (FT-IR spectra), were utilized to analyze the structures of two types of CQDs. The results revealed that nitrogen doping profoundly alters the carbon structure, promoting a shift from diamond-like carbon (sp3 C) to graphite carbon (sp2 C). This alteration greatly hastens the graphitization process of the CQDs, thereby broadening fluorescence emission specturm. Moreover, the fluorescenet properties of N-doped CQDs showed a pronounced sensitivity to pH variations. Specifically, the fluorescent properties of N-doped CQDs demonstrated notable sensitivity to pH variations. It was quantitatively represented by two distinct linear relationships: in acidic conditions, it follows y = 0.28 + 1.08 ∗ x , and in alkaline conditions, y = 15.06 - x . (where y is the normalized fluorescence intensity and x is the pH value). For original CQDs, the change is less pronounced, with a linear relationship of y = 6.62 - 0.022 ∗ x . Therefore, the N-doped CQDs exhibit a strong correlation between the fluorescence intensity and pH value in both acidic and alkaline environments, while also demonstrating the ability to change fluorescence color, indicating its potential applications in rapid response and convenient pH detection. [ABSTRACT FROM AUTHOR]

Seven increasing levels of water salinity from 0.029 to 0.600 M (as NaCl) were used to investigate the dependence of pH measurement, performed using colorimetric sensor arrays (CSAs), on ionic strength. The CSAs were arrays of sensing spots prepared in the form of sol–gel-embedding Bromothymol Blue (BB) and Bromocresol Green (BCG) in a porous nitrocellulose support. The support was impregnated over the entire thickness (≈100 µm), allowing for the signal (Hue) acquisition on the opposite side to the contact with the sample solution. Three CSAs were prepared, M1, M2, and M3. M1 contained a free cationic surfactant, hexadecyltrimethylammonium p-toluenesulfonate (CTApTs), for modulating the p K a of the indicators. In M2, the surfactant dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DTSACl) was covalently bonded to the sol–gel. M3 was prepared like M2 but using a larger amount of ethanol as the solvent for the synthesis. The modulation of the CTApTs or the DTSACl concentration enabled the tuning of the p K a . In general, the p K a modulation ability decreased with the increase in salinity. The presence of a surfactant covalently linked to the backbone partially reduced the competitiveness of the anionic species, improving the results. Nevertheless, the salt effect was still present, and a correction algorithm was required. Between pH 5.00 and 12.00, this correction could be made automatically by using spots taken as references to produce sensors independent of salinity. As the salt effect is virtually absent above 0.160 M, M2 and M3 can be used for future applications in seawater. [ABSTRACT FROM AUTHOR]

The high alkaline condition of concrete naturally protects embedded steel bars from corrosion by forming a passive protective film. The pH of concrete is generally high, but concrete with different mix compositions may have various pH values. The pH of concrete may decrease over time due to long-term mechanical, chemical, biological and physical factors. Therefore, monitoring the pH value of concrete is crucial to checking if its alkalinity is within an acceptable range and ensuring that the concrete structure is in good health condition. However, the pH measurement for cement-based materials is not standardised. Ex-situ leaching, one of the recommended methods for pH measurement, is simple and practical. In this method, the sample will be crushed, leached and tested using a pH electrode probe. The lifespan of the pH electrode probe may decrease due to the existing suspended particles in the solution. Therefore, one recommendation is to filter the solution before using the probe. In this study, the effect of different filtering setups on the pH value of a cement mortar with a cement-to-sand ratio of 1:3 was evaluated. pH test results showed that filtering can produce similar outcomes to those without filtering, regardless of the type of filter paper and its pore size. However, filtering is strongly recommended for electrode protection of the pH meter. As an innovative filtering setup for cement-based materials, syringe filtering was introduced in this study because it is more economical and its operation is simpler compared to the other methods.

The article provides stability and parenteral compatibility study guidelines for authors applying manuscript submissions to the journal. It describes the stability study design which covers assay validation and sample preparation. It discusses requirements in stability study including physical assays, storage and sampling, statistical considerations, stability and beyond-use-date definition, reporting results and stability of biologic drugs. An overview of compatibility study design is given.

A new construction of a potentiometric sensor was introduced for the first time. It relies on the use of two membranes instead of one, as in the well-known coated-disc electrode. For this purpose, a new electrode body was constructed, including not one, but two glassy carbon discs covered with an ion-selective membrane. This solution allows for the sensor properties to be enhanced without using additional materials (layers or additives) on the membrane. The new construction is particularly useful for in situ measurements in environmental samples. Two ion-selective polymeric membranes were used, namely H+ and K+-selective membranes, to confirm the universality of the idea. The tests conducted included chronopotentiometric tests, electrochemical impedance spectroscopy, and potentiometric measurements. The electrical and analytical parameters of the sensors were evaluated and compared for all tested electrodes to evaluate the properties of the planar electrode versus previously known constructions. Research has shown that the application of two membranes instead of one allows for the resistance of an electrode to be lowered and for the electrical capacitance to be elevated. Improving the electrical properties of an electrode resulted in the enhancement of its analytical properties. The pH measurement range of the planar electrode is 2–11, which is much wider in contrast to that of the single-membrane electrode. The linear range of the K+-selective planar electrode is wider than that of the coated-disc electrode and equals 10−6 to 10−1 M. The response time turned out to be a few seconds shorter, and the potential drift was smaller due to the application of an additional membrane in the electrode construction. This research creates a new opportunity to design robust potentiometric sensors, as the presented construction is universal and can be used to obtain electrodes selective to various ions.

Background: The measurement of pH values within chronic wounds is essential for effective wound management. However, fabricating fiber optic sensors for wound monitoring presents challenges due to materials characteristics. This study focuses on the fabrication and characterization of a viscosity-modified polymeric optical fiber-based biosensor system for pH measurement. Methods: A PEO/PEG/ PVA blended polymer with varying ratios (PEO 1-10, PEG 1-4, and PVA 1-0.1) and molecular weights at 50% concentration was used to fabricate the fiber optic preforms using the cast-in-mould method, and a direct drawing was performed at 37°C to create the fiber. The optimal PEO/PEG/PVA ratio for the fabricated fiber was found to be 5:4:1, 5:3:1, which displayed a tensile strength of 7.41 MPa and good morphological features. Results: The fabricated fiber showed improved optical characteristics, including transparency, by varying the polymeric ratio and adding PVA. When compared to a standard PMMA fiber, the fabricated fiber exhibited a pH-sensitive pattern in light intensity response to different pH media, demonstrating a direct correlation between pH value and optical intensity output. The biosensor system successfully measured pH values within a media, with PMMA and fabricated fiber output at pH 1 and 10 being 0.172 and 0.15, 3.71 and 0.75, respectively. Conclusion: The fabricated fiber optic biosensor system shows potential for pH measurement in chronic wounds with further study. [ABSTRACT FROM AUTHOR]

Ionic liquids have attracted immense attention due to their unique properties and potential industrial applications. Green ionic liquids such as amino acid‐based ionic liquids (AAILs) are promising solvents due to their proven low toxicity. The properties of newly known substances are unavailable, especially when they are in aqueous solutions. This information is essential, and they must be understood before employing these materials in any application for technical, safety, and economical reasons. In this study, three types of AAILs were examined, namely; 1‐octyl‐3‐methylimidazolium glycine [OMIM][Gly], 1‐octyl‐3‐methylimidazolium alanine [OMIM][Ala], and 1‐octyl‐3‐methylimidazolium proline [OMIM][Pro]. The aqueous solutions were prepared at concentrations of 1, 10, 20, and 30 wt.%. The pH and electrical conductivity were measured at room temperature and atmospheric pressure. Moreover, volumetric properties such as density, molar volume, excess molar volume, and thermal expansion were also determined at atmospheric pressure over a temperature range of 298.15–338.15 K. An empirical correlation was also developed to correlate the volumetric parameters with temperature and concentration. The results showed that AAILs solutions are alkaline in nature. Moreover, they increase the electrical conductivity of water. Additionally, molar volume, excess molar volume, and isobaric thermal expansion increased as the temperature increased, whereas the density decreased with an increase in temperature. A discussion on the effect of anions was presented. The developed empirical correlation exhibited an accurate prediction of the volumetric properties with R2 > 0.9762. [ABSTRACT FROM AUTHOR]

Seven increasing levels of water salinity from 0.029 to 0.600 M (as NaCl) were used to investigate the dependence of pH measurement, performed using colorimetric sensor arrays (CSAs), on ionic strength. The CSAs were arrays of sensing spots prepared in the form of sol–gel-embedding Bromothymol Blue (BB) and Bromocresol Green (BCG) in a porous nitrocellulose support. The support was impregnated over the entire thickness (≈100 µm), allowing for the signal (Hue) acquisition on the opposite side to the contact with the sample solution. Three CSAs were prepared, M1, M2, and M3. M1 contained a free cationic surfactant, hexadecyltrimethylammonium p-toluenesulfonate (CTApTs), for modulating the pKa of the indicators. In M2, the surfactant dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DTSACl) was covalently bonded to the sol–gel. M3 was prepared like M2 but using a larger amount of ethanol as the solvent for the synthesis. The modulation of the CTApTs or the DTSACl concentration enabled the tuning of the pKa. In general, the pKa modulation ability decreased with the increase in salinity. The presence of a surfactant covalently linked to the backbone partially reduced the competitiveness of the anionic species, improving the results. Nevertheless, the salt effect was still present, and a correction algorithm was required. Between pH 5.00 and 12.00, this correction could be made automatically by using spots taken as references to produce sensors independent of salinity. As the salt effect is virtually absent above 0.160 M, M2 and M3 can be used for future applications in seawater.

The real-time monitoring of the pH values of alcoholic beverages was performed with a compact wireless device based on a colorimetric detection method with the Hue (H) as the analytical signal working in a pH range of 2.50–6.50. This device represents the first colorimetric pH meter reported in the literature monitoring in real-time the pH value of colored solutions. This pH meter consists of I) a nitrocellulose membrane impregnated with a pH-sensitive gel; II) a CCD camera for color acquisition; III) an electronic board with the calibration profiles of H vs. pH, and IV) a display to read the measured pH. It was applied to the pH determination of a white wine, a prosecco white wine, and a double malt beer leading to the values of pH wine = 3.30, pH prosecco = 3.33, pH beer = 4.29. The analytical performance is comparable to the glass electrode with an accuracy error ≤ 0.05 pH units. [Display omitted] • First colorimetric pH meter with real-time monitoring of wine and beer pH. • The nitrocellulose support enables the in-line detection of pH. • Sensor reusable, robust, and stable over one month. • pH errors comparable to the ones of the glass electrode. [ABSTRACT FROM AUTHOR]

Because of the COVID 19 pandemic, we now utilise hand sanitizer in our daily lives. Hand hygiene has become a legal requirement. Infection control is becoming a requirement. Hand hygiene is widely regarded as the most practical and effective way of infection prevention. Hand sanitizer is thought to have played a significant role in reducing illness transmission to patients. Because it is more cost-effective and efficient. The efficiency of hand sanitizer is totally determined by how it is used. There are two sorts of hand sanitizers on the market. 1) Hand sanitizer with alcohol 2) Hand sanitizer that isn't alcohol-based. Most effective hand sanitizers contain 70 percent to 95 percent alcohol, which has the potential to denature microbial protein and inactivate viruses. The impact of hand sanitizer on human health care is significant, and this review article will provide you with information on several elements of hand sanitizer

Today, the development of nanomaterials with sensing properties attracts much scientific interest because of the demand for low-cost nontoxic colloidal nanoprobes with high sensitivity and selectivity for various biomedical and environment-related applications. Carbon dots (CDs) are promising candidates for these applications as they demonstrate unique optical properties with intense emissions, biocompatibility, and ease of fabrication. Herein, we developed synthesis protocols to obtain CDs based on o-phenylenediamine with a variety of optical responses depending on additional precursors and changes in the reaction media. The obtained CDs are N-doped (N,S-doped in case of thiourea addition) less than 10 nm spherical particles with emissions observed in the 300–600 nm spectral region depending on their chemical composition. These CDs may act simultaneously as absorptive/fluorescent sensing probes for solvent polarity with ∆ S / ∆ E N T   up to 85, for ∆ E N T from 0.099 to 1.0 and for pH values in the range of 3.0–8.0, thus opening an opportunity to check the pH in non-pure water or a mixture of solvents. Moreover, CDs preserve their optical properties when embedded in cellulose strips that can be used as sensing probes for fast and easy pH checks. We believe that the resulting dual-purpose sensing nano probes based on CDs will have high demand in various sensing applications. [ABSTRACT FROM AUTHOR]

As a fundamental and essential property, gastrointestinal (GI) tract pH reflects its condition and changes in several GI diseases such as inflammatory bowel disease (IBD), gastritis, etc. As a result, accurately measuring the GI pH is crucial for treatment, diagnosis, and prevention of GI diseases and contributes to developing GI disease models for basic studies. However, among pH measuring studies with animal models, there is no reliable method that can reflect the value and changing trends of GI pH in actual patients. In the current study, we developed a fast, simple method with pH indicator paper to measure the GI pH changes with GI content in normal mice and mice with colitis or hepatitis. Results demonstrated that normal mice's mean GI pH values were between 6.0 and 8.0, which was consistent with previous reports. Furthermore, the GI pH of colitis and hepatitis model mice showed the same pattern of lower values in the intestine and higher values in the stomach compared with normal mice. Our simple and timesaving method can accurately measure the dramatic changes in the GI pH of mice with GI diseases and is suitable for measuring the pH of sticky liquids with limited volume. Given all the merits listed above, this method is helpful for further research. • A simple and timesaving method to measure gastrointestinal (GI) tract pH in mice. • GI pH changes in animal models reflect pH changes in actual patients. • First time to report GI pH changes in the hepatitis model mice. [ABSTRACT FROM AUTHOR]

The advent of implanted medical devices has greatly improved the quality of life and increased longevity. However, infection remains a significant risk because bacteria can colonize device surfaces and form biofilms that are resistant to antibiotics and the host’s immune system. Several factors contribute to this resistance, including heterogeneous biochemical and pH microenvironments that can affect bacterial growth and interfere with antibiotic biochemistry; dormant regions in the biofilm with low oxygen, pH, and metabolites; slow bacterial growth and division; and poor antibody penetration through the biofilm, which may also be regions with poor acid product clearance. Measuring pH in biofilms is thus key to understanding their biochemistry and offers potential routes to detect and treat latent infections. This review covers the causes of biofilm pH changes and simulations, general findings of metabolite-dependent pH gradients, methods for measuring pH in biofilms, effects of pH on biofilms, and pH-targeted antimicrobial-based approaches.

pH is a measure of the hydrogen ion activity in a solution, which is a function of temperature. Under normal seawater conditions, it is well constrained. Nowadays, with an increasing interest in complex environments (e.g., sea ice), a better understanding of the temperature change on pH under extreme conditions is needed. The objective of this paper was to investigate the temperature coefficient of the seawater pH (ΔpH/ΔT) over a wide range of temperature, pH, dissolved inorganic carbon (DIC) and salinity by a method of continuous pH measurement with the temperature change, and to verify the application of CO2SYS for pH conversion under extreme conditions (on the National Bureau of Standards (NBS) scale and the total proton scale). Both experimental results and CO2SYS calculations showed that ΔpH/ΔT was slightly affected by temperature over the range of 0°C to 40°C and by pH (at 25°C) from 7.8 to 8.5. However, when pH was out of this range, ΔpH/ΔT varied greatly with pH value. According to the experimental results, changes in DIC from 1 mmol/kg to 5 mmol/kg and salinity from 20 to 105 had no significant effect on ΔpH/ΔT. CO2SYS calculations showed a slight increase in ΔpH/ΔT with DIC on both the NBS scale and the total proton scale; and underestimated ΔpH/ΔT at high salinity (i.e., beyond the oceanographic range) on the NBS scale. Nevertheless, CO2SYS is still suitable for pH conversion even under extreme conditions by simply setting the input values of DIC and salinity in CO2SYS within the oceanographic range (e.g., DIC=2 mmol/kg and S=35). [ABSTRACT FROM AUTHOR]

All-solid-stated pH sensors based on metal/ metal oxide were widely used in mixed heterogeneous environment, such as soil or soilless cultivation. In this study, an all-solid-stated pH sensor prepared by magnetron sputtering was presented, of which the working electrode was antimony, and reference electrode was Ag/AgCl electrode, and heat treated process was conducted to improving the performance of all-solid-stated planar pH sensor. The electrodes heat treated at the temperature of 100°C, 200°C, 300°C, and 400°C were tested through surface morphology analysis, energy spectrum analysis and electrochemical experiments. The results showed that the heat-treated temperature had a remarkable effect on the performance of the pH sensor. Specifically, the pH sensor heat-treated at 200°C had excellent performance, with the sensitivity 74.0 mV/pH, the response time less than 3 s, the standard deviation less than 2 mV in 700 s period. The developed sensor can be applied in pH detection in soilless culture and is promising to popularize in industrial production. [ABSTRACT FROM AUTHOR]

Macronutrients (carbohydrates, fat and protein) are the cornerstones of daily diet, among which carbohydrates provide energy for the muscles and central nervous system during movement and exercise. The breakdown of carbohydrates starts in the oral cavity, where they are primarily hydrolyzed to glucose and then metabolized to organic acids. The end products may have an impact on the oral microenvironment, so it is necessary to monitor the process of microbial metabolism and to measure the pH change. Although a pH meter has been widely used, it is limited by its sensitivity. We then introduce a light addressable potentiometric sensor (LAPS), which has been used in extracellular acidification detection of living cells with the advantages of being objective, quantitative and highly sensitive. However, it is difficult to use in monitoring bacterial metabolism because bacteria cannot be immobilization on the LAPS chip as easily as living cells. Therefore, a microphysiometric system integrated with Transwell insert and microfluidic LAPS chip was designed and constructed to solve this problem. The decrease in pH caused by glucose fermentation in Lactobacillus rhamnosus was successfully measured by this device. This proves the feasibility of the system for metabolism detection of non-adhere targets such as microorganisms and even 3D cells and organoids. [ABSTRACT FROM AUTHOR]

An optical pH sensor that enables the non-destructive measurement of acetic acid and its distribution in a photovoltaic module during damp heat (DH) testing is reported. The sensor was fabricated by impregnating a solution of a pH-sensitive fluorescent dye into a fluororesin membrane filter, which was then dried. While conducting the DH test, fluorescence spectra from 20 pH sensors were periodically recorded and converted into pH values using a predetermined calibration curve. As a result, we succeeded in measuring changes in pH with a DH test time of up to 2000 h, and it was possible to obtain information on the pH distribution in the module. We also confirmed no change in pH in a module with a silicone encapsulant free from acetic acid, and revealed that the sensor that we developed does not respond to moisture and heat, but only to acetic acid. [ABSTRACT FROM AUTHOR]

In this study, a prototype based on fuzzy logic (FL) controller and internet of things (IoT) was developed to monitor rumen health parameters in cattle. In the system build as a prototype, the monitoring process related to the parameters is followed through three different applications developed on the Android operating system, the Thingspeak service and the WEB environment. The first application, which is an Android-based program, warns the user in case of any abnormality related to the rumen health. The other two applications allow monitoring and analyzing rumen health parameters in real time. The system implements a process that measures at varying time intervals to display the values of rumen health parameters, pH and temperature. The management of this process is carried out by the FL controller depending on the pH and temperature changes. This measurement, which is made at varying time intervals, is the most important feature that distinguishes our study from studies in the literature. Because in the studies reported in the literature, measurements are made at fixed time intervals. The relevant feature brings with it two important contributions for the system we propose. The first is to accelerate the precautions to be taken regarding animal health by enabling the system to measure at more frequent intervals in cases of deterioration in the pH level of rumen. The second is to reduce the energy consumed by the parameter measuring device from the battery by allowing the system to measure at longer intervals when the pH level of rumen is in balance. [ABSTRACT FROM AUTHOR]

This work presents multiplexable fiber optical sensors to perform multiple-point pH measurements. Using a femtosecond laser direct writing approach, array of intrinsic Fabry-Peìrot interferometer (IFPI) sensors were inscribed in standard single-mode fibers. A sol-gel dip coating process was used to deposit Palladium-doped Titanium Dioxide (Pd-TiO2) sensory film on IFPI sensors to perform pH measurement, while an uncoated sensor was used to measure temperature of aquatic solutions to remove influence of temperature fluctuation on pH measurements. Pd nanoparticles in sensory films acts as catalyst to convert hydrogen ion in aquatic solutions Pd hydride, which produce strains to IFPI sensors. White light interferometry demodulation algorithm was applied to resolve strain exerted to IFPI sensors induced by pH value changes in aquatic solution. The sensor exhibits reversible and reproducible response in aquatic solution with pH value from 1.0 to 7.0 at the room temperature. The response time of the pH sensors was approximately 7 s for all measurements performed. The sensor technology demonstrated in this paper has a potential to perform multi-point pH and temperature measurements using a single fiber. [ABSTRACT FROM AUTHOR]

pH of soilless culture substrate is an important and frequently measured property in facility agriculture. Compared with laboratory analysis, pH direct measurement (pH-DM) involving the direct insertion of a pH sensor into soil or substrates, is rapid, efficient, and inexpensive. This method requires a reliable pH sensor and exhibits a significant measuring error of 0.8 to 1.1. In this study, all-solid-stated pH sensors were fabricated on alumina substrate through magnetron sputtering. Substrates containing mixed peat and vermiculite were prepared to examine the effects of mass water content (MWC) and mixture ratio on the pH-DM method. Statistical analysis of the measured pH values demonstrated that MWC and mass ratio of peat ($\boldsymbol {\eta }_{{peat}}$) evidently influenced pH-DM. Specifically, in the unsaturated substrate, the errors of pH-DM were highly and negatively correlated with MWC but positively correlated with $\boldsymbol {\eta }_{{peat}}$. The measured pH values also exhibited wide dispersion in the substrates with high $\boldsymbol {\eta }_{{peat}}$ or extremely low MWC. Furthermore, a two-factor compensation model was established and evaluated. The compensation results indicated that the maximum error with pH-DM method decreased from −1.63 to −0.66 pH unit, and the fluctuation coefficient of pH-DM decreased from 0.796 to 0.264. The influence rules of MWC and $\boldsymbol {\eta }_{{peat}}$ on errors in the pH-DM method, as well as the proposed compensation model, are useful in improving the accuracy and robustness of pH-DM and can contribute to rapid and efficient pH measurements in soilless culture substrate. [ABSTRACT FROM AUTHOR]

This paper presents ISFET array based pH-sensing system-on-ultra-thin-chip (SoUTC) designed and fabricated in 350 nm CMOS technology. The SoUTC with the proposed current-mode active-pixel ISFET circuit array is desined to operate at 2 V and consumes 6.28 μW per-pixel. The presented SoUTC exhibits low sensitivity to process, voltage, temperature and strain-induced (PVTS) variations. The silicon area occupancy of each active-pixel is 44.9 × 33.5 µm2 with an ion-sensing area of 576 µm2. The design of presented ISFET device is analysed with finite element modeling in COMSOL Multiphysics using compact model parameters of MOSFET in 350 nm CMOS technology. Owing to thin (∼30 µm) Si-substrate the presented SoUTC can conform to curvilinear surfaces, allowing intimate contact necessary for reliable data for monitoring of analytes in body fluids such as sweat. Further, it can operate either in a rolling shutter fashion or in a pseudo-random pixel selection mode allowing the simultaneous detection of pH from different skin regions. Finally, the circuits have been tested in aqueous Dulbecco's Modified Eagle Medium (DMEM) culture media with 5–9 pH values, which mimics cellular environments, to demonstrate their potential use for continuous monitoring of body-fluids pH. [ABSTRACT FROM AUTHOR]

Healthy reinforced concrete should be highly alkaline to safeguard the passive protective film for reinforcement of steel bars against corrosion. pH measurement is gaining importance in research of cement-based materials (CBMs), such as paste, mortar and concrete, as well as in structural health monitoring and forensic engineering applications. However, insufficient information is available regarding the most practical, economical and applicable quantitative pH measurement method for CBMs from the sampling to measurement stage. Existing recommended methods for measuring pH have many variables that need to be investigated to determine how they influence the pH value. Samples were recommended to be ground into very fine particles for pH measurement. Preparing very fine particles of CBMs is costly and time consuming, while larger particles, with sizes similar to sand particles, are easier to obtain, without needing special equipment. This study aims to investigate the effect of different particle sizes on the pH of cement mortar. Mortar specimens were crushed and sieved to obtain different ranges of particle sizes to measure the pH values. Results showed that specimens with large particle sizes (between 600 µm and 4.75 mm) can produce similar results to specimens with very fine particle sizes (<600 µm) by increasing the solid-to-solvent ratio or the leaching time. [ABSTRACT FROM AUTHOR]

Today, the development of nanomaterials with sensing properties attracts much scientific interest because of the demand for low-cost nontoxic colloidal nanoprobes with high sensitivity and selectivity for various biomedical and environment-related applications. Carbon dots (CDs) are promising candidates for these applications as they demonstrate unique optical properties with intense emissions, biocompatibility, and ease of fabrication. Herein, we developed synthesis protocols to obtain CDs based on o-phenylenediamine with a variety of optical responses depending on additional precursors and changes in the reaction media. The obtained CDs are N-doped (N,S-doped in case of thiourea addition) less than 10 nm spherical particles with emissions observed in the 300–600 nm spectral region depending on their chemical composition. These CDs may act simultaneously as absorptive/fluorescent sensing probes for solvent polarity with ∆S/∆ENT up to 85, for ∆ENT from 0.099 to 1.0 and for pH values in the range of 3.0–8.0, thus opening an opportunity to check the pH in non-pure water or a mixture of solvents. Moreover, CDs preserve their optical properties when embedded in cellulose strips that can be used as sensing probes for fast and easy pH checks. We believe that the resulting dual-purpose sensing nano probes based on CDs will have high demand in various sensing applications.

In the preservation of cultural heritage, the measurement of pH has implications both as a parameter for assessing the state of conservation and as a reference for the preparation and use of aqueous treatment solutions. Few studies in the relevant literature, however, deal with evaluating the reliability of measurements. The purpose of this study was to identify the best method and the confidence limits for measurements of surface pH on linen canvas. The results obtained with the two main methods currently used, water drop and rigid gel, were evaluated and compared with warm extraction. Agarose at different concentrations was used for preparing rigid gels, and the influence of the volume of the gel was also evaluated in the latter measurements. Five canvas samples with different degree of acidity were tested: highly acidic, acidic, weakly acidic, a new linen canvas, and the lining canvas recovered from a painting dating around the middle of nineteenth century. The theoretical surface pH values (pHst), derived from the measurements obtained by the aqueous extraction method, were used as standards against which to assess the reliability of the measurements. [ABSTRACT FROM AUTHOR]

Submicron metakaolin (SMK) is an ultrafine aluminosilicate material, which was used for improving properties of cement slurry in this paper. SMK was added to the slurry mix as a partial substitute for Portland cement in proportions of 1%, 3%, 5% and 7%. To explore the influence of SMK on hydration of cement slurry, the heat flow and pH measurement was used to indicate that SMK significantly increased the rate of heat release and total heat release, increase the rate of calcium hydroxide (CH) generation in the pore solution at initial stage of hydration. The hardened specimens at different ages (3 – 28 days) were measured by X-ray diffraction, Differential Thermal Analysis and Compressive strength. The results showed that: SMK displayed pozzolanic effect which reduced CH content and increased the generation of Calcium Silicate Hydrate (C-S-H) gel at later stages of hydration. The compressive strength tests showed that SMK highest increased compressive strength of the slurry by 67% and 19% at 3d and 28d over plain cement slurry. It was concluded that SMK could improve many properties of cement slurry and has the use potential on actual projects. [ABSTRACT FROM AUTHOR]

• Optical fiber sensor for pH measurement as low-cost solution. • pH sensitive material as polyaniline using synthetic oxidative polymerization on optical fiber surface. • Transition between protonated and deprotonated polyaniline increasing RI of the layer as the pH increases. • FBGs inscribed by UV laser in tapering fiber and D-shaped fiber as optical solution. • Sensors with good reproducibility and repeatability with excelent sensitivities for tapers and D-shape fibers. Optical fiber sensors show potential for monitoring multiple parameters essential to the growth and health of fish, particularly the pH value of the aquaculture medium. Two types of optical fiber sensors, using tapered silica single mode fibers with a Bragg grating inscribed and D-shaped plastic optical fibers (home-made and reused) were produced. A pH-sensitive layer made of polyaniline (PANI) was deposited on the optical fibers' surface. The sensors demonstrated reproducibility and repeatability with a sensitivity of −0.22 ± 0.02 dB/pH, −472 ± 9 Counts/pH, and −(26 ± 2) × 102 Counts/pH for tapers, D-shape home-made, and reused, respectively, but only for increasing pH. Stabilization time tests indicated that a minimum of 60 s is required for a stable response, with no significant cross-sensitivities regarding temperature and ionic strength. [ABSTRACT FROM AUTHOR]

Positive pulsed discharge plasma is generated above a test liquid containing NaCl in Ar atmosphere, and H+ distribution and a temperature variation in the liquid are, respectively, visualized by colorimetric methods using methyl red (MR) and microencapsulated thermotropic liquid crystals (MTLCs). The discharges generated above the liquid containing MR and MTLCs have almost the same characteristics in the waveforms of discharge voltage and current, and the appearance of discharges. The generation of H+ and the temperature increase in the liquid are induced below the discharge area, and H+ distribution and temperature-increased area expand similarly, by the plasma exposure. The spatiotemporal measurement of temperature distribution in the liquid is also observed with MTLCs using a sheet laser. It is found that temperature increase is measured just below the extremity of the discharge and distributes in a torus form and that no temperature increase occurs below the middle of the discharge area. Since good similarity is observed between the H+ distribution and the temperature increase in the test liquid, H+ distribution probably expands in a concentric configuration from the generation area with the plasma exposure time. [ABSTRACT FROM AUTHOR]

The measurement of arterial oxygen saturations, end-tidal carbon dioxide and pH are all key to modern anaesthetic practice. They can all be measured in a variety of ways, but the most common are discussed in this article. The understanding of the underlying physical principles and how the anaesthetist monitors function to measure these variables is discussed in this article, including limitations and inaccuracies of each technique. [ABSTRACT FROM AUTHOR]

Macronutrients (carbohydrates, fat and protein) are the cornerstones of daily diet, among which carbohydrates provide energy for the muscles and central nervous system during movement and exercise. The breakdown of carbohydrates starts in the oral cavity, where they are primarily hydrolyzed to glucose and then metabolized to organic acids. The end products may have an impact on the oral microenvironment, so it is necessary to monitor the process of microbial metabolism and to measure the pH change. Although a pH meter has been widely used, it is limited by its sensitivity. We then introduce a light addressable potentiometric sensor (LAPS), which has been used in extracellular acidification detection of living cells with the advantages of being objective, quantitative and highly sensitive. However, it is difficult to use in monitoring bacterial metabolism because bacteria cannot be immobilization on the LAPS chip as easily as living cells. Therefore, a microphysiometric system integrated with Transwell insert and microfluidic LAPS chip was designed and constructed to solve this problem. The decrease in pH caused by glucose fermentation in Lactobacillus rhamnosus was successfully measured by this device. This proves the feasibility of the system for metabolism detection of non-adhere targets such as microorganisms and even 3D cells and organoids.

An optical pH sensor that enables the non-destructive measurement of acetic acid and its distribution in a photovoltaic module during damp heat (DH) testing is reported. The sensor was fabricated by impregnating a solution of a pH-sensitive fluorescent dye into a fluororesin membrane filter, which was then dried. While conducting the DH test, fluorescence spectra from 20 pH sensors were periodically recorded and converted into pH values using a predetermined calibration curve. As a result, we succeeded in measuring changes in pH with a DH test time of up to 2000 h, and it was possible to obtain information on the pH distribution in the module. We also confirmed no change in pH in a module with a silicone encapsulant free from acetic acid, and revealed that the sensor that we developed does not respond to moisture and heat, but only to acetic acid.

We present a novel all‐fiber probe with 710‐μm outside diameter for combined optical coherence tomography and pH detection. In cancer surgery, a significant challenge is how to completely remove the malignant tumor without cutting too much normal tissue. The difference between cancer tissue and normal tissue not only lies in morphology and structure but also in tissue pH, where malignant tissue has a lower pH. This dual‐modality probe combined optical coherence tomography and pH detection of biological tissue, is expected to determine whether the tissue is cancerous quickly and accurately. The probe utilizes a typical three‐segment structure (double‐clad fiber ‐ no‐core fiber ‐ graded‐index fiber). We obtained a lateral resolution of ~10.6 μm, a working distance of ~506 μm and a pH measurement accuracy of 0.01 pH unit for the probe. The performance of the all‐fiber probe was verified through an ex vivo experiment using the porcine brain specimen. [ABSTRACT FROM AUTHOR]

A pH colorimetric sensor array (CSA) was prepared on a nitrocellulose membrane and used for accurate pH measurement in highly concentrated saline solutions. The CSAs consisted of sensing spots made of a suitable OrMoSil polymer prepared from organo-fluorinated-silane precursors and/or organosilane with tetraethyl orthosilicate hosting an acid-base indicator. Four CSAs were prepared: D, 1F, 2F, and 3F. In D, a nonfluorinated organosilane was present. From 1F to 3F, the concentration of the fluorinated organosilane increased and improved the pH measurement accuracy in highly saline concentrations. No recalibrations were required, and the analytical signal was stable in time. D, 1F, 2F, and 3F were deposited in triplicate, and they were prepared to work in the seawater pH interval (7.50-8.50). The use of fluorinated precursors led to a lower pH prediction error and tailored the interval of the CSA at more basic pH values so that the inflection points of the sigmoidal calibrations of D, 1F, 2F, and 3F moved from 6.97 to 7.98. The overall pH prediction error was 0.10 pH (1F), 0.02 pH (2F), and 0.04 pH units (3F). The CSAs were stable, reversible, reusable, and independent of salinity ( S ) between 20 and 40. The performances of the CSA were compared with those of a glass electrode, whose pH NIST values were converted in the pH SWS scale through a conversion equation. Being unaffected by the typical drawback of the glass electrode, the CSAs can be used directly in seawater real samples, and it validated the proposed conversion equation.

Background: The biofield is a controversial concept among the scientific community. Some aspects of this phenomenon relate to measurable factors of mainstream science such as electromagnetics, while others, involving nonlocal interventions, intention, and consciousness, seem to produce physical changes through mechanisms that are still unknown, making the outcomes of many studies not fully explained by our current state of scientific understanding. This study explored the hypothetical effects of intention on the conditioning of a pH system with continuous data acquisition for real-time measurements. As a follow-up study, those effects were related to changes in the physicochemical properties of water samples chosen as a target in a previous large-scale intervention of focused intention. Methods: The intention experiments were conducted under controlled conditions from the 8th to September 11, 2015. During this period, 286 qualified biofield therapy practitioners meditated at a distance with the intention of changing the vibrational state of the water molecules contained in specific flasks. Several variables were evaluated, including the magnetic field and ultraviolet-visible (UV-VIS) radiation from 175 to 954 nm near the experimental spot, as well as Raman spectra, pH, and electrical conductivity of all the water samples. After this period, real-time pH measurements of water samples were taken with the same equipment and under the same experimental conditions, except for the practitioners' awareness of those experiments, and without their focused intention. Real-time pH, electrical conductivity and the concentration of cations and anions measured by ion chromatography in the water samples were used to test the proposed hypothesis. Results: Real-time pH was responsive during the intention experiments and after this period. Further continuous measurements performed after the 11th September showed that the pH variations overtime kept a systematic and consistent tendency similar to the one observed during the experimental activities involving focused intention. After the replacement of the electrode internal electrolyte, this behavior was no longer verified, and the pH was stable as the initial tests to evaluate the equipment sensitivity. Conclusions: After the experimental period involving focused intention, the pH system maintained a systematic and consistent behavior while measuring the pH of new water samples. An eventual intention-mediated conditioning of the pH measurement system occurred because of changes in the properties of the electrode internal electrolyte. [ABSTRACT FROM AUTHOR]

The dichromatism of Bromophenol blue (BPB) was investigated by varying its concentration in the absence and presence of surfactant. A model of the indicator behavior was carried out, justifying the experimental shapes of the sigmoidal profiles of the hue (H) coordinate. The model applied to the solution was compared with the performance of colorimetric sensor arrays (CSAs) with increasing BPB concentrations. The H shape and the prediction errors of the CSAs were very similar to those predicted. The experimental results enable the changing of the slope of the calibration profiles, at will, by varying only the BPB concentration.

Objetivo: Evaluar la eficacia de una matriz autóloga en el tratamiento de úlceras de pie diabético (UPD) de difícil cicatrización, y analizar la respuesta inmune a la aplicación de la matriz con un escáner de infrarrojo cercano (NIRS, por sus siglas en inglés) y un medidor de pH dérmico. Método: Tres pacientes fueron tratados con una matriz de coágulo de sangre completa (WBC, por sus siglas en inglés) autóloga. La matriz se realizó en el punto de atención, mezclando la sangre del paciente con una suspensión coloidal de gluconato de calcio/caolín, e inyectándola en una bandeja de coagulación. Se formó un gel de WBC y se aplicó a las heridas. El gel de WBC se mantuvo en su lugar con apósitos primarios y secundarios. Resultados: Hubo una reducción del tamaño de las UPD de 70% tras dos aplicaciones, 97,6% después de tres aplicaciones, y 90,9% tras cuatro aplicaciones. El NIRS midió un aumento en la saturación de oxígeno tisular. No hubo reacciones adversas. Conclusión: La matriz autóloga fue eficaz en el tratamiento de las UPD. La superficie de las UPD se redujo después de cada aplicación y se logró el cierre completo de las heridas. Se necesitan más ensayos clínicos para comprender mejor los beneficios de la matriz de WBC en UPD. Conflicto de interés: RedDress Ltd. (Pardes-Hanna, Israel) proporcionó los suministros y materiales del estudio. Bennett Health Inc. ayudó con el desarrollo del protocolo y capacitó al personal sobre la aplicación del producto para coágulos sanguíneos. JA es accionista de Bennett Health Inc. No hubo interés financiero para ninguno de los investigadores o participantes. [ABSTRACT FROM AUTHOR]

The capability to measure pH is fundamental in many fields ranging from healthcare and agrifood, to chemistry and industrial applications. In medicine, the possibility of in-line and real-time monitoring critical care analytes, such as pH, is recognized to provide relevant information for the diagnosis and treatment of a variety of disorders and would be of considerable support for the management of extracorporeal (blood) circulation (ECC). In this article, we theoretically and experimentally investigate the performances and the robustness of a fluorescent sensor that we recently proposed for the in-line and real-time monitoring of blood pH in ECC. Indeed, being low-cost and biocompatible, the proposed sensor can be advantageously exploited for the in-line and real-time monitoring of the pH of fluids, particularly in applications such as healthcare where safe and low-cost disposables are usually required for all parts which come into contact with the patient. The reported results demonstrate that the proposed sensor allows achieving significant robustness to unevennesses in the production process of the sensing element. [ABSTRACT FROM AUTHOR]

The possibility of real-time monitor critical care analytes, such as pH, is recognized to provide relevant information for the diagnosis and treatment of a variety of disorders and would be of considerable support for the management of extracorporeal circulation (ECC). However, despite that blood pH can be measured from a long time by using electrodes or point-of-care instruments, such as blood-gas analyzers, costs, and complications associated with such measurement methods limit their use, thus, blood pH is generally not monitored during routinary ECC. In this article, we propose to exploit the tubing composing the ECC line to realize a low-cost and disposable pH-sensor and to interrogate such fluorescent sensors by using optical radiations. The proposed measuring system avoids complications related to blood sampling and may allow achieving single-patient cost requirements. Preliminary tests performed on a real ECC bloodline demonstrate that the system can operate with blood in ECC. Indeed, a 6-h ECC treatment simulated using bovine blood revealed a deviation with respect to the reference pH-meter typically of about a few thousandths pH and with a maximum of about 0.01 pH. [ABSTRACT FROM AUTHOR]

[Display omitted] • The stability domain of Be(OH) 2 was detremined by thermodynamic calculations and pH measurements. • The degree of passivation of Be(OH) 2 was evaluated by open circuit potential measurements and electrochemical impedance spectroscopy as a function of the pH solution. • Be is protected against the corrosion from neutral to basic pH. The corrosion is the lowest around pH 12. Beryllium wastes produced by nuclear industry could be managed by encapsulation in cements. The main risk is the aqueous corrosion, which leads to the hydrogen production and cracks causing a loss of radioactivity confinement. However, the corrosion can be limited by the formation of the hydroxide solid phase Be(OH) 2(s). A study on the influence of the pH on the reactivity of beryllium was carried out in aqueous solution. The solubility diagram was drawn and showed that the hydroxide solid phase is stable until very high basic pH of 14. The pH variation of solution at different initial pH was measured after immersion of metallic beryllium. The results are in good agreement with the calculated solubility diagram. The open circuit potential (OPC) and the electrochemical impedance spectra (EIS) were recorded at a beryllium electrode from pH 2 to 15. The simulation of the EIS by using an electric equivalent circuit allowed to evaluate the Be reactivity by measuring the charge transfer resistance as a function of the pH. The experimental results confirm that the corrosion of beryllium is limited at neutral to basic pH and this low reactivity was attributed to the formation of the hydroxide solid phase Be(OH) 2. The OCP and EIS measurements put also in evidence that the corrosion of beryllium is the lowest in solution having pH around 12. In this pH range, the Be metal would be protected against the corrosion both by the formation of the hydroxide solid Be(OH) 2 and by the adsorption of hydroxide ions (OH−) at the metal surface. [ABSTRACT FROM AUTHOR]

Tea is the most popular hot beverageworldwide. In 2020, the value of the global tea market was almost USD 200 billion, and is estimated to reach up to USD 318 billion by the year 2025. Tea has been included as part ofa regular diet for centuries because of its various health benefits. However, tea is acidic, and over-consumption causes heat problems, disturbance of the sleep cycle, tooth erosion, and low calcium absorption in the body. Strong tea concentration is very harmful and toxic. The safe consumption of tea should be guaranteed. The treatment applied in this research work is on sensory mechanisms and Arduino UNO. The objective of this paper is to find out community interest in a particular tea species and inform them about tea overdose.The acidity is mapped with tea taste in terms of strong, medium, and low flavors. Based on the data analysis, the results differentiatethe acidity level of black tea (pH: 3.89–4.08) as very high, green tea (pH: 4.68–4.70) is in the 2nd position, and the energy drink Herbalife Nutrition (pH: 5.59–5.64) is the least acidic comparatively, with a proportion ratio 1:10 of tea to water. Experimental analysis reveals that in the additives, lemon is most acidic, followed byginger, lemongrass, and Tulasi.

Healthy reinforced concrete should be highly alkaline to safeguard the passive protective film for reinforcement of steel bars against corrosion. pH measurement is gaining importance in research of cement-based materials (CBMs), such as paste, mortar and concrete, as well as in structural health monitoring and forensic engineering applications. However, insufficient information is available regarding the most practical, economical and applicable quantitative pH measurement method for CBMs from the sampling to measurement stage. Existing recommended methods for measuring pH have many variables that need to be investigated to determine how they influence the pH value. Samples were recommended to be ground into very fine particles for pH measurement. Preparing very fine particles of CBMs is costly and time consuming, while larger particles, with sizes similar to sand particles, are easier to obtain, without needing special equipment. This study aims to investigate the effect of different particle sizes on the pH of cement mortar. Mortar specimens were crushed and sieved to obtain different ranges of particle sizes to measure the pH values. Results showed that specimens with large particle sizes (between 600 µm and 4.75 mm) can produce similar results to specimens with very fine particle sizes (

The surface pH is a critical factor in the quality and longevity of materials and products. Traditional fast colorimetric pH detection-based tests such as water quality control or pregnancy tests, when results are determined by the naked eye, cannot provide quantitative values. Using standard pH papers, paper-printed comparison charts, or colorimetric microfluidic paper-based analytical devices is not suitable for such technological applications and quality management systems (QMSs) where the particular tested material should contain a suitable indicator in situ, in its structure, either before or after the process, the technology or the apparatus that are being tested. This paper describes a method based on the combination of impregnation of a tested material with a pH indicator in situ, its exposure to a process of technology whose impact on pH value is to be tested, colorimetric pH measurement, and approximation of pH value using derived pH characteristic parameters (pH-CPs) based on CIE orthogonal and cylindrical color variables. The hypotheses were experimentally verified using the methyl red pH indicator, impregnating the acid lignin-containing paper, and preparing a calibration sample set with pH in the range 4 to 12 using controlled alkalization. Based on the performed measurements and statistical evaluation, it can be concluded that the best pH-CPs with the highest regression parameters for pH are √∆E, ln (a),√∆H (ab), a/L, h/b and ln (b/a). The experimental results show that the presented method allows a good estimation of pH detection of the material surfaces.

Deoxyribonucleic acid (DNA) sequencing technology provides important data for the disclosure of genetic information and plays an important role in gene diagnosis and gene therapy. Conventional sequencing devices are expensive and require large and bulky optical structures and additional fluorescent labeling steps. Sequencing equipment based on a semiconductor chip has the advantages of fast sequencing speed, low cost and small size. The detection of DNA base pairing is the most important step in gene sequencing. In this study, a large-scale ion-sensitive field-effect transistor (ISFET) array chip with more than 13 million sensitive units is successfully designed for detecting the DNA base pairing. DNA base pairing is successfully detected by the sensor system, which includes the ISFET microarray chip, microfluidic system, and test platform. The chip achieves a high resolution of at least 0.5 mV, thus enabling the recognition of the change of 0.01 pH value. This complementary metal-oxide semiconductor (CMOS) compatible and cost-efficient sensor array chip, together with other specially designed components, can form a complete DNA sequencing system with potential application in the molecular biology fields.

Diabetes is a metabolic disorder that affects more than 400 million people worldwide. Most existing approaches for measuring fasting blood glucose levels (FBGLs) are invasive. This work presents a proof-of-concept study in which saliva is used as a proxy biofluid to estimate FBGL. Saliva collected from 175 volunteers was analysed using portable, handheld sensors to measure its electrochemical properties such as conductivity, redox potential, pH and K^+, Na^+ and Ca^2+ ionic concentrations. These data, along with the person's gender and age, were trained and tested after casewise annotation with their true FBGL values using a set of mathematical algorithms. An accuracy of 87.4 ± 1.7% and a mean relative deviation of 14.1% (R^2 = 0.76) was achieved using a mathematical algorithm. All parameters except the gender were found to play a key role in the FBGL determination process. Finally, the individual electrochemical sensors were integrated into a single platform and interfaced with the authors’ algorithm through a simple graphical user interface. The system was revalidated on 60 new saliva samples and gave an accuracy of 81.67 ± 2.53% (R^2 = 0.71). This study paves the way for rapid, efficient and painless FBGL estimation from saliva.

The high alkaline condition of concrete naturally protects embedded steel bars from corrosion by forming a passive protective film. The pH of concrete is generally high, but concrete with different mix compositions may have various pH values. The pH of concrete may decrease over time due to long-term mechanical, chemical, biological and physical factors. Therefore, monitoring the pH value of concrete is crucial to checking if its alkalinity is within an acceptable range and ensuring that the concrete structure is in good health condition. However, the pH measurement for cement-based materials is not standardised. Ex-situ leaching, one of the recommended methods for pH measurement, is simple and practical. In this method, the sample will be crushed, leached and tested using a pH electrode probe. The lifespan of the pH electrode probe may decrease due to the existing suspended particles in the solution. Therefore, one recommendation is to filter the solution before using the probe. In this study, the effect of different filtering setups on the pH value of a cement mortar with a cement-to-sand ratio of 1:3 was evaluated. pH test results showed that filtering can produce similar outcomes to those without filtering, regardless of the type of filter paper and its pore size. However, filtering is strongly recommended for electrode protection of the pH meter. As an innovative filtering setup for cement-based materials, syringe filtering was introduced in this study because it is more economical and its operation is simpler compared to the other methods., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

According to the Spanish National Research Council (CSIC) report, the ex-situ leaching method (ESL) is more appropriate and accurate than other methods for measuring pH value in terms of repeatability and reproducibility. In this study, the ESL method was used to measure the pH value of cement matrix materials. The design test process aimed to avoid underestimating the variation in pH during the process of solution stirring and pH measurement without using both argon and nitrogen to block the specimen contact with air, with good repeatability and reproducibility. This study also considered the influence of the dryness of the specimen before crushing, the size of the powder, the air-exposed specimen, the air-exposed solution, the temperature of the solution, etc. After testing and analysis, a standard procedure for detecting the pH value of cement matrix materials was established which is known as the S-ESL method.