pH Meter Research Articles

Integrative liquid chromatography-tandem mass spectrometry metabolomics and high-throughput sequencing technology reveal physicochemical characteristics and bacterial diversity of traditionally pickled mustard tuber from different regions of China

Abstract Objectives This work aimed to investigate and compare the physicochemical properties and bacterial diversity of traditionally pickled mustard tuber from different regions in China. Materials and Methods The pickles were obtained from Ningbo (NB), Nei Monggol (NMG), and Harbin (HEB). The pH was monitored by a pH meter. The titratable acidity and salinity were determined via titrimetric analysis. The nitrite content was measured using N-(1-naphthyl)-ethylenediamine dihydrochloride spectrophotometric method. The organic acids were detected by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The bacterial diversity was conducted through Illumina high-throughput sequencing platform. Results There were significant differences in the physicochemical properties of pickled mustard tuber from various locations, with the NB pickles having the highest pH, salinity, and nitrite content and the lowest titratable acidity. Importantly, pickles with higher titratable acidity levels had relatively lower nitrite and salinity contents. A total of 63 organic acids were detected, with lactic acid and succinic acid being the most prevalent. Moreover, the organic acid compositions of the NMG and HEB samples were more similar than those of the NB pickles. Additionally, bioinformatic analysis revealed that Firmicutes and Proteobacteria appeared as the predominant bacterial phyla in all samples. Among these, Lactobacillus was the major genera. The most abundant bacteria were found in the HEB pickles. Further correlation analysis showed that there was a strong correlation between bacterial community and 11 internal physicochemical parameters. Conclusions This study could contribute to a better understanding of the physicochemical characteristics and bacterial diversity of pickled mustard tuber from different locations.

Design expert based optimization of the pyrolysis process for the production of cattle dung bio-oil and properties characterization

This study aimed to optimize pyrolysis conditions to maximize bio-oil yield from cattle dung, a waste product of livestock practices. Pyrolysis of cattle dung was carried out in batch type reactor. The pyrolysis process was optimized using a central composite design in response surface methodology, with conversion parameters such as pyrolysis temperature, vapor cooling temperature, residence time, and gas flow rate taken into account. The cattle dung bio-oil was analyzed using gas chromatography/mass spectroscopy (GC/MS), an elemental analyzer, a pH probe, and a bomb calorimeter. Furthermore, the ASTM standard procedures were used to determine the bio-fuel characteristics. The optimized conditions were found to be a pyrolysis temperature of 402 °C, a vapor cooling temperature of 2.25 °C, a residence time of 30.72 min, and a gas flow rate of 1.81 l min−1, resulting in a maximum bio-oil yield of 18.9%. According to the findings, the yield of bio-oil was predominantly affected by pyrolysis temperature and vapor cooling temperature. Moreover, the bio-oil that was retrieved was discovered to be similar to conventional liquid fuels in numerous ways.

A tale of two pumps: Blue light and abscisic acid alter Arabidopsis leaf hydraulics via bundle sheath cell H+-ATPases.

The bundle sheath cell (BSC) layer tightly enveloping the xylem throughout the leaf is recognized as a major signal-perceiving "valve" in series with stomata, regulating leaf hydraulic conductance (Kleaf) and thereby radial water flow via the transpiring leaf. The BSC blue light (BL) signaling pathway increases Kleaf and the underlying BSC water permeability. Here, we explored the hypothesis that BSCs also harbor a Kleaf-downregulating signaling pathway related to the stress phytohormone abscisic acid (ABA). We employed fluorescence imaging of xylem sap in detached leaves and BSC protoplasts from different genotypes of Arabidopsis (Arabidopsis thaliana) plants, using pH and membrane potential probes to monitor physiological responses to ABA and BL in combination with pharmacological agents. We found that BL-enhanced Kleaf required elevated BSC cytosolic Ca2+. ABA inhibited BL-activated xylem-sap-acidifying BSC H+-ATPase AHA2 (Arabidopsis H+-ATPase 2), resulting in depolarized BSCs and alkalinized xylem sap. ABA also stimulated BSC vacuolar H+-ATPase (VHA), which alkalinized the BSC cytosol. Each pump stimulation, AHA2 by BL and VHA by ABA (under BL), also required Ca2+. ABA stimulated VHA in the dark depending on Ca2+, but only in an alkaline external medium. Taken together with earlier findings on the pH sensitivity of BSC osmotic water permeability (i.e. aquaporin activity), our results suggest a Ca2+-dependent and pH-mediated causative link between the BL- and ABA-regulated activities of two BSC H+-ATPases and Kleaf.

Li+ doped SrAl2O4:Eu2+, Dy3+ long‐persistent luminescence aluminoborosilicate glass‐ceramics: Preparation and properties

AbstractIn the SrO‐Al2O3‐B2O3‐SiO2 glass system, a SrAl2O4:Eu2+, Dy3+ long‐persistent luminescence glass‐ceramic (SAGC) with Li2O was successfully synthesized for the first time using the recrystallization‐melting method. The composition, micromorphology, long‐persistent luminescence (LPL) properties, photoluminescence (PL) properties, and water resistance were measured by X‐ray diffractometer, scanning electron microscope, brightness meter, fluorescence spectrophotometer, and pH meter, respectively. The method involves the formation of grains below the glass transition temperature, followed by the formation of the glass phase at a higher temperature, and finally the formation of products through cooling. The samples exhibited green PL and LPL emissions and demonstrated excellent color purity, homogeneity, and LPL luminescence. After doping Li2O, the purity and crystallinity of the SrAl2O4 were improved, and scalene hexagonal or monoclinic prismatic SrAl2O4 crystals with high regularity were synthesized in the glass matrix. This research indicates that excellent LPL benefits from the complete crystal structure, abundant crystals, and large crystal size. When the Li2O content reached 5 mol%, the crystal size was ∼30 µm, the PL and LPL properties performed best, and greater water resistance was exhibited. The SAGC in this new glass system has potential in optical storage.

DIFFERENCES IN FLOW RATE AND SALIVA PH IN USERS AND NON-USERS OF FIXED ORTHODONTIC APPLIANCES

Introduction: Fixed orthodontic treatment is a type of dental treatment that is very popular throughout the world, not only to improve function but also lifestyle. However, it has an impact on the condition of the oral cavity, namely the flow rate and pH of salivary, which can affect dental and oral health. This study aims to determine the differences in flow rate and saliva pH between users and non-users of fixed orthodontic devices. Materials and Methods: This type of research is analytical observational, with a cross sectional approach. The population in this study were students class 2020, 2021, and 2022, the sample in this study was 116 students. Data collection by observation, interviews and examination. The method for measuring saliva flow rate with drainase and saliva pH using the Hanna HI98107 pH meter. Univariate and bivariate data analysis (independent sample t test). Results and Discussions: The results of the study showed that the there was a difference in saliva flow rate in users and non-users of fixed orthodontic appliances (p-value 0.001), there is a difference in saliva pH between users and non-users (p-value 0.000). Conclusion: The use of fixed orthodontic can affect saliva flow rate and salivary pH.

Physical Compatibility Between Intravenous Magnesium Sulfate and Potassium or Sodium Phosphate in a Pediatric Intensive Care Unit.

Objective:To evaluate the physical compatibility between intravenous magnesium sulfate and potassium and sodium phosphate, a common electrolyte intravenous supplementation in pediatric intensive care units. Study design: Magnesium sulfate was mixed separately with potassium phosphate and sodium phosphate at ratios of 1:1, 1:4, and 4:1. Binary mixtures were prepared, in triplicate and under sterile conditions, by permuting the order of addition. The undiluted pure drugs were used as controls for possible sequence effects. Visual changes, turbidity, and pH were assessed immediately after mixing (baseline) and at 4 and 24 hours. Two observers performed visual changes by naked-eye visual inspection in order to search visible haze, particulate matter, gas formation, or color change. Turbidity was measured by nephelometry and incompatibility was defined as an increase of ≥0.5 nephelometric turbidity units (NTU) from baseline. pH was measured using a portable pH meter and incompatibility was defined as a variation of >1 pH unit during the observation period. Results: None of the admixtures exhibited visual changes or significant variations in turbidity (increases of ≥0.5 in nephelometric turbidity units) or pH (changes of >1 unit) during the observation period and neither compared with baseline. Conclusion: In this study, no visual changes were observed, and turbidity and pH evaluated by instrumental methods remained within acceptable limits and showed no significant variations from baseline, therefore no physical incompatibility between magnesium sulfate and potassium or sodium phosphate was found.

Fibras solúvel e insolúvel em dietas de leitões na creche

This study evaluated the effect of diets containing low levels of soluble and insoluble fiber sources on performance, diarrhea score, chemical and physical characteristics of feces, and behavior in weaning piglets. Thirty-six weaned piglets of 30 days of age with an initial body weight of 8.8 kg were distributed in 36 pens using a completely randomized design in an experimental period of 21 days. The experimental treatments were the Control diet (CONT), the Control diet + 1% beet pulp inclusion (SBP), and the Control diet + 1% lignocellulose inclusion (LCE, Arbocel®). Feed and water were available ad libitum. Body weight and feed intake were measured weekly to calculate the average daily intake, weight gain, and feed conversion ratio. The fecal consistency was determined visually twice daily, classifying feces according to three scores. To determine fecal pH and concentration of fecal short-chain fatty acids (SCFA), samples of fresh feces were collected two weeks after weaning and measured by a digital pH meter and gas chromatography, respectively. The behavior of piglets was observed once a week, using four animals per treatment, from 14:00 to 16:00, every 12 min. Fibre sources had no effect (P>0.05) on performance, except in the period 15 to 21 days after weaning, which was a tendency (P=0.061) of feed intake decrease in SBP and LCE diets. Fiber sources did not affect the fecal consistency score (P>0.05). However, piglets fed SBP and LCE showed a tendency (P<0.10) to have less diarrhea incidence 15 to 21 days post-weaning and in the entire experimental period. Fecal pH and SCFA concentration were not influenced by fiber source (P>0.05), with acetic, propionic, and butyric acids representing around 71%, 19%, and 10% of the total, respectively. Fiber sources did not influence the social and feeding behavior of weaning piglets (P>0.05). Diets containing 1% fiber sources did not alter performance, diarrhea score, fecal pH, fecal SCFA concentration, or feeding and social behavior of weaned piglets.

A digital bar pH indicator based on a microfluidic paper-based analytical device

A pH value of an aqueous medium is an essential parameter in the environment and biology. Nowadays, it is possible to measure using a colorimetric pH paper or an electrochemical pH meter. However, since the two methods have drawbacks of the limited precision in pH determination and the careful management of a glass membrane electrode, respectively, it still remains as a challenge to discover a user-friendly, reliable pH-measuring device. Herein, a novel digital bar pH indicator was developed using a microfluidic paper-based analytical device (μPAD) to determine with the naked eye the pH value of an aqueous sample. The fabricated digital indicator consists of seven independent pH sensors displaying a color change from yellow to greenish blue above specific pH values. These sensing elements were vertically aligned to form a bar shape, and their color-changing pH points were regulated to increase upward from 4.5 to 7.5 with an interval of 0.5 units. For fast and simultaneous detection of the colorimetric sensors, sample addition to an inlet of the μPAD was quickly transported vertically along a hollow paper channel, horizontally divided, and arrived at the detection zones at similar times via delay channels. Through independent experiments, control of the color-changing pH point and flow rate were confirmed by addition of a surfactant additive into the pH indicator and inserting empty spaces in a flow channel, respectively. Reliable operation of the fabricated μPAD was verified using standard pH buffer samples. Finally, the feasibility of our digital bar pH indicator was successfully demonstrated for determining the pH value of a urine sample under the resolution of 0.5 units.

PH-Responsive Aminobenzocoumarins as Fluorescent Probes for Biological Acidity.

Regulation of pH plays an essential role in orchestrating the delicate cellular machinery responsible for life as we know it. Its abnormal values are indicative of aberrant cellular behavior and associated with pathologies including cancer progression or solid tumors. Here, we report a series of bent and linear aminobenzocoumarins decorated with different substituents. We investigate their photophysical properties and demonstrate that the probes display strong pH-responsive fluorescence "turn on" behavior in highly acidic environments, with enhancement up to 300-fold. In combination with their low cytotoxicity, this behavior enabled their application in bioimaging of acidic lysosomes in live human cells. We believe that these molecules serve as attractive lead structures for future rational design of novel biocompatible fluorescent pH probes.

Unlicensed antiviral products used for the at-home treatment of feline infectious peritonitis contain GS-441524 at significantly different amounts than advertised.

To analyze the content of unlicensed GS-441524-like products being used as a largely successful at-home treatment for cats suspected to have FIP. The remdesivir content and pH were also measured. 127 injectable and oral samples from 30 of the most popular brands of black market producers. Unlicensed GS-441524-like products were procured through donations and tested for GS-441524 and remdesivir content by liquid chromatography with tandem mass spectrometry. A pH meter measured the pH of injectable samples. Of the 87 injectable formulations, 95% contained more (on average 39% more) GS-441524 than expected based on the producer's marketed concentrations. The average pH (1.30 pH) was well below the physiologic pH conditions recommended for SC injections. The oral formulations were more variable, with 43% containing more GS-441524 (on average 75% more) than expected and 58% containing less (on average 39% less) than the expected content. There was minimal variability in GS-441524 content between replicate samples in the injectables formulations (measured by coefficient of variation). One injectable and 2 oral samples additionally contained remdesivir. All unlicensed products used for the at-home treatment of FIP that we tested contain GS-441524. The injectables generally contain significantly more drug than advertised at a below-physiologic pH. Unlicensed oral products vary more widely in drug content and suffer from unconventional dosing and labeling. These data should highlight the need for regulation of these products and the development of legal pathways to procure GS-441524.

Determination of Fluoride Levels and pH in Community Drinking Water Supply across Pune City, Maharashtra

Context: The knowledge of fluoride levels and pH in potable water is important for health-care personnel and policymakers in general and dentists in particular, but the data regarding fluoride levels and pH of community drinking water in Pune City are deficient. Aims: The aim of this study was to determine the fluoride levels and pH in community drinking water supply across Pune City, Maharashtra. Subjects and Methods: In an in vitro, experimental study, a total of 30 water samples were collected from one water treatment plant, one water storage reservoir, and three adjoining residential areas of the Pune Municipal Corporation (PMC) and Pimpri Chinchwad Municipal Corporation (PCMC) region. They were analyzed for fluoride content using (2-(parasulfophenylazo)-1,8-dihydroxy-3,6-naphthalene disulfonate) based-spectrophotometric method, and for pH using a digital pH meter. Statistical Analysis Used: Fluoride and pH values were subjected to Mann–Whitney U-test and intragroup comparison of fluoride and pH levels at various levels of water distribution was performed using Kruskal–Wallis test. Results: The mean concentration of fluoride and the pH in water samples from different locations across Pune City were 0.262 and 7.02 mg/L, respectively. Although levels across various sources were different, there was no statistical difference between the fluoride content or the pH of the water from sources across PMC and PCMC regions. Conclusions: The fluoride content of the community water supply of Pune City was below the recommended standards yet within the permissible limits in considering the temperature range in Pune City across different seasons. The pH of the drinking water of Pune City was optimal.

25份市售金银花代用茶的质量调查及活性成分分析数据集

To further improve the quality standard of honeysuckle (Lonicera japonica Thunb.) tea, we investigated and analyzed the quality-related characteristics of the 25 brands of commercial honeysuckle tea in this study. Following the general label rules of prepackaged food, this study assessed the label compliance of different brands of honeysuckle tea. Furthermore, we conducted an investigation and assigned grades to the characters of honeysuckle tea in accordance with the agricultural industry standard. The pH value of the sample was measured using a pH meter. The total flavonoid content was determined through ultraviolet spectrophotometry. The content of chlorogenic acid was determined using HPLC. The correlation and distribution characteristics of the data were analyzed by means of SPSS, Microsoft Excel and other statistical tools. Based on a survey of 25 commercially available honeysuckle samples, a total of 361 test results were obtained. This dataset is expected to offer valuable references for the development of national standards for honeysuckle substitute tea.

The Effect of Fermented Jicama Extract with Lactobacillus plantarum B1765 as the Culture Starter on the Product Quality and Flavonoid Contents

Jicama (Pachyrhizus erosus) is a functional food containing phenolic compounds, with the main compounds being flavonoids. However, the presence of polyphenol oxidase and the structure of flavonoid compounds are still bound in the form of glycosides, so the bioactivity of jicama is not maximized. This study aims to determine the effects of jicama extract fermentation on product quality and increased flavonoid content in jicama. Fermentation was performed for 0, 12, 24, and 36 hours with 5% (v/v) of the starter culture, Lactobacillus plantarum B1765, at 37ºC. The result showed that fermentation times could increase Total Lactic Acid Bacteria (LAB), Total Tertitrable Acid (TTA), Total Phenolic Content (TPC), and Total Flavonoid Content (TFC). It also influenced a decrease in pH. The total LAB count was determined using the Total Plate Count method, the Total Tertitrable Acid was determined using acid-base titration, and the pH was determined using a pH meter. Total Phenolic Content was measured using the Folin-Ciocalteu method, and Total Flavonoid Content was measured using AlCl3 and potassium acetate. The analysis of the data revealed that jicama extract fermented optimum after 24 hours, with a total LAB count of 9.7x107±0.31 CFU/mL, a pH value of 4.21±0.22, a TTA of 0.376±0.025%, but TPC and TFC still increasing until 24 hours of fermentation to 16.22±0.312 mg GAE/g, and of 29.01±0.641 mg QE/g respectively. Fermentation of jicama extract with Lactobacillus plantarum B1765 increased total phenolic and total flavonoid contents and could be used as a functional food product.

Advantages of a novel in situ pH measurement for soilless media.

Rhizosphere pH determines nutrient bioavailability, but this pH is difficult to measure. Standard pH tests require adding water to growth media. This dilutes hydrogen ion activity and increases pH. We used a novel, in situ, pointed-tip electrode to estimate rhizosphere pH without dilution. Measurements from this electrode matched a research-grade pH meter in hydroponic nutrient solutions. We then compared measurements from this electrode to saturated paste and pour-through methods in peat moss, coconut coir, and pine bark. The pointed-tip electrode was unable to accurately measure pH in the highly-porous pine bark media. Adding deionized water to the other media at container capacity using the saturated paste method resulted in a pH that was 0.59 ± 0.30 units higher than the initial in situ measurement at the top of the container. This increase aligns with established solution chemistry principles. Measurements of pH using the pour-through method were 0.38 ± 0.24 pH units higher than in situ measurements at the bottom of the container. We conclude that in situ pH measurements are not subject to dilution and are thus more representative of the rhizosphere pH than the saturated paste and pour-through techniques.

Total Flavonoid Content and In Vitro Anti-Inflammatory Potentials of Kombucha with Enrichment of Butterfly Pea (Clitoria ternatea) Flower Extract

Kombucha is a fermented beverage from tea (Camellia sinensis) that is claimed to be beneficial for several medical ailments. Several studies have conducted nutritional enrichment of kombucha to optimize its nutritional benefits. One of the native Indonesian plants that can be utilized as nutritional enrichment material is the butterfly pea (Clitoria ternatea) flower. Its nutrition is expected to increase the health benefits of kombucha Camellia sinensis. Kombucha has beneficial compounds such as flavonoids that have potential applications in medical chemistry due to its anti-inflammatory properties. This study aims to enrich the valuable nutrition and test the in vitro anti-inflammatory potentials of kombucha, conducted by formulating kombuchaCamellia sinensis with Clitoria ternatea flower extract addition (0; 0.5; 1; 1.5; 2)% (m/v), the chemical characterization including pH value test using digital pH meter and total flavonoid content (TFC) using colorimetric (AlCl3) assay) with quercetin as its standard, and in vitro anti-inflammatory activity test using the red blood cell (RBC) membrane stabilization method. The result showed that the pH value of kombucha had met the consumption quality standard (3-4), starting from 3,30 + 0,00 (0%) to 3,66 + 0,01 (2%). The flavonoid content increased from 38,89 + 0,05 mgQE/g (0%) to 126,73 + 0,13 mgQE/g (2%). Kombucha samples showed anti-inflammatory activity potentials with the best IC50 value of 140,22 ppm (2% addition). The data from this study were analyzed using a one-way ANOVA statistical test. It shows there is an influence from the addition of Clitoria ternatea to the TFC result (p<0,05), and it continued to Duncan's Multiple Range test (DMRT) that showed sample F0 to F4 were significantly different from each other (p<0,05). In conclusion, the enrichment of kombucha (Camellia sinensis) using Clitoria ternatea flower extract has been proven to increase the health-beneficial compound (flavonoids) and have potential anti-inflammatory activity.

Abstract 4158: Non-invasive mapping of acidosis and extracellular lactosis for assessing tumor invasion in vivo

Abstract Tumor cells typically display a hyperglycolytic metabolic phenotype characterized by increased lactate production, known as the Warburg effect. This drift in oxidative metabolism often results in a more acidic microenvironment. This adverse microenvironment represents a unique metabolic signature in cancer cells with more invasive phenotypes. However, to date, there are no effective methods available to evaluate cancer progression and metastatic potential in vivo. To bridge this gap, we have developed a molecular imaging technique (CEST-MRI) that can track extracellular pH (pHe; acidoCEST) and extracellular lactate levels (shiftCEST) simultaneously to discern different cancer phenotypes. In this study we have generated and selected in vivo two PyMT derived murine breast cancer cell lines, a parental and a G6 metastatic. We first characterized the cell’s metabolism by analyzing key biomarkers with qPCR, Western Blot and microscopy, and confirmed their distinct metabolic profiles with Seahorse and RNA Sequencing. Notably, the metastatic PyMT exhibited a more active metabolism, aligning with the invasive phenotype observed by spheroid invasion assay. Herein, we combined the injection of iopamidol and shift reagent (SR) to perform quasi-simultaneous acidoCEST and shiftCEST. First, we assessed the approach in vitro by introducing iopamidol and SR into phantoms containing the individual contrast agents, and the combination in pure water and cells supernatants at different pHe and lactate levels. We performed LDH assays to cross-validate the extracellular concentrations and monitored the pH with a micro pH meter (Mettler-Toledo). In vivo, the cells were injected orthotopically in the 4th mammary fat pad of C57BL/6N mice. Hybrid shift/acidoCEST sequences were optimized and acquired following the injection of the iopamidol+SR solution. Preclinical shift/acidoCEST enabled the simultaneous and accurate determination of extracellular acidosis and lactosis, revealing increased acidification in the metastatic models despite lower lactate secretion. Metastatic tumors exhibited a negative correlation between tumor volume and pHe, indicating the significance of acidity in mutagenesis and invasion. In contrast, no correlation was observed for the parental non-metastatic tumor. Additionally, the metastatic tumors had lower levels of lactate than the parental tumors, which could be attributed to their higher mitochondrial activity, reflecting a diverted metabolic fitness. In summary, our study highlights the efficacy of shift/acidoCEST as a reliable method for non-invasive metabolic imaging, enabling the simultaneous detection of extracellular acidity and lactate production by MRI. This research introduces a unique platform for assessing the metabolic aggressiveness of cancer, emphasizing the significance of acidity and lactate production as crucial biomarkers in cancer invasion. Citation Format: Anais Choffart, Remy Chiaffarelli, Max Zimmermann, Laura Kuebler, André Martins. Non-invasive mapping of acidosis and extracellular lactosis for assessing tumor invasion in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4158.

A capillary-aided microfiber Bragg grating pH sensor for hydrovoltaic technology

Hydrovoltaic is an emerging technology that aims to harvest energy from water flow and evaporation, in which the plasmonic hydrogen ions are generated by the interaction between water and hydrovoltaic device. However, the volume of the water sample for the interaction is usually ultra-small due to the compact size of hydrovoltaic device, making the quantification and characterization of the hydrogen ions in such water sample an elusive goal. To address this issue, a miniature fiber-optic pH probe is proposed using a unilaterally tapered-microfiber Bragg grating. The microfiber Bragg grating has an intrinsic Bragg reflection signal with a narrow linewidth. The fiber probe is functionalized by coating the sodium alginate, which can respond to the variation of pH mediated by the alteration of the hydrophilicity. The rigidity and robustness of microfiber Bragg grating facilitates the encapsulation of the sensor into a sampling capillary, allowing for the detection of trace aqueous sample less than 2 μL. The pH sensitivity of the tapered-μFBG-based sensor is 62.8 p.m./pH (R2 = 0.995) with a limit resolution of 0.096 pH. The sensor performed a practical application in the monitoring and characterization of the hydrovoltaic microdevice, which can generate microcurrent as soaked in the water. This work demonstrates a promising technology in the fields of materials, energy, biology and medicine, in which the detection of the microsamples is inevitable.

Mineralogical and geochemical characteristics of the Nkoteng-Mbandjock alluvial clays from Sanaga valley deposits (Cameroon, Central Africa): Implications for source weathering and provenance

This research investigates the physico-chemical, mineralogical and geochemical attributes of alluvial clayey sediments in the Nkoteng-Mbandjock regions of the Sanaga valley, Cameroon. The primary objective is to elucidate the source area-weathering and provenance of these sediments. Grain size distribution analyses were conducted using the Robinson-Kӧln's pipetting method. The physico-chemical parameters were evaluated by an HACH-HQ11d brand electric pH meter, while the mineralogical compositions were determined by X-ray Diffraction. Major and trace element concentrations were measured employing X-ray Fluorescence and Inductively Coupled Plasmas-Mass Spectrometry. Textural classification identified the Sanaga valley alluvial clay deposits as predominantly silty clayey and clayey muddy. Geochemical classification diagram positioned them in the shale and Fe-shale fields. Weathering indices of alteration exhibited a consistent trend indicating a high degree of weathering in the source rock. A low Na2O/K2O ratio (average 0.18) and a high Index of Compositional Variability (ICV; average 2.29) suggested immature sediments. Additionally, low SiO2/Al2O3 ratio (average 3.93) implied an origin from stable settings with recycled inputs. These characteristics were further supported by elemental ratios such as Zr/Sc (average 47.12), U/Th (average 0.24) and Th/Sc (average 1.48). Furthermore, indicators like V/Cr (average 1.17), U/Th (average 0.24) and authigenic U (average −1.67) values suggested the deposition of the Sanaga valley alluvial clay under oxic conditions. The collective analysis of major and trace element distribution revealed felsic sources with minimal contributions from mafic rocks. These findings contribute to a comprehensive understanding of the geological processes and conditions influencing the composition and characteristics of the studied alluvial clay deposits in the Sanaga valley.

Peeling the onion: additional layers of regulation in the acid stress response.

Bacteria are capable of withstanding large changes in osmolality and cytoplasmic pH, unlike eukaryotes that tightly regulate their pH and cellular composition. Previous studies on the bacterial acid stress response described a rapid, brief acidification, followed by immediate recovery. More recent experiments with better pH probes have imaged single living cells, and we now appreciate that following acid stress, bacteria maintain an acidic cytoplasm for as long as the stress remains. This acidification enables pathogens to sense a host environment and turn on their virulence programs, for example, enabling survival and replication within acidic vacuoles. Single-cell analysis identified an intracellular pH threshold of ~6.5. Acid stress reduces the internal pH below this threshold, triggering the assembly of a type III secretion system in Salmonella and the secretion of virulence factors in the host. These pathways are significant because preventing intracellular acidification of Salmonella renders it avirulent, suggesting that acid stress pathways represent a potential therapeutic target. Although we refer to the acid stress response as singular, it is actually a complex response that involves numerous two-component signaling systems, several amino acid decarboxylation systems, as well as cellular buffering systems and electron transport chain components, among others. In a recent paper in the Journal of Bacteriology, M. G. Gorelik, H. Yakhnin, A. Pannuri, A. C. Walker, C. Pourciau, D. Czyz, T. Romeo, and P. Babitzke (J Bacteriol 206:e00354-23, 2024, https://doi.org/10.1128/jb.00354-23) describe a new connection linking the carbon storage regulator CsrA to the acid stress response, highlighting new additional layers of complexity.

Use of Preoperative Endoscopic Capsule-Based pH Testing Before Bariatric Surgery.

Vertical sleeve gastrectomy is the most performed bariatric operation in the US; however, a significant number of patients suffer from persistent or new-onset reflux. No consensus for objective preoperative evaluation in these patients exists. We compared capsule-based pH testing vs GERD symptom scoring to determine extent of preoperative GERD to aid in procedure selection for bariatric surgery. An IRB-approved retrospective review of consecutive patients at a single institution was performed from April 2021 to December 2022. During initial consultation for bariatric surgery, a validated GERD symptom subjective survey was administered. All patients demonstrating interest in sleeve gastrectomy or had a history of reflux underwent upper endoscopy with capsule-based pH testing. Sixty-two patients underwent preoperative endoscopy with capsule-based pH testing and completed GERD symptom assessment survey(s). Median BMI was 43.4 kg/m 2 and 66.1% of patients were not taking a proton-pump inhibitor before performance of pH testing. There was negligible linear association between the objective DeMeester score obtained by capsule-based pH probe and GERD symptom survey scores. Median GERD symptom survey scores did not differ between patients with and without a diagnosis of GERD based on pH testing (all p values >0.11). An objective method for identifying severe GERD in the preoperative assessment may aid in the decision tree for procedure selection and informed consent process. Patients with significant preoperative GERD may be at higher risk for future GERD-related sleeve complications. Capsule-based pH testing may prove to be superior to subjective symptom scoring systems in this patient population.