pH Range Research Articles

Bacterial Cellulose Incorporating Multicolor Fluorescent Probes for Visual Acidity Detection in Paper-Based Cultural Relics.

Paper-based cultural relics often undergo acidification and deterioration during long-term preservation. Accurate detection of paper acidity is of great significance to assess aging status and extend the preservation lifetime of paper-based cultural relics. Rapid identification of the acidification degree and acid distribution across multiple regions of paper is essential. Inspired by fluorescent sensing technology, pH-sensitive cadmium telluride (CdTe) quantum dots (QDs) and rhodamine B (RB) fluorescent probes are synthesized and incorporated onto the nanofibers of a bacterial cellulose (BC) membrane to enable visual acidity detection of paper. Due to the complementary pH detection range of CdTe QDs and RB probes, the composite BC membrane exhibits a clear pH response across an acidic to neutral range (pH 3.0-7.5). Notably, the contrasting fluorescent colors of the two probes within the BC membrane allow for easy visualization of paper pH and acidity distribution with the naked eyes. A distinct color transition from red to green was observed on the fluorescent BC membrane when it is applied to a model paper with a gradient pH distribution. The feasibility of this method was verified by using the flat-headed pH electrode method. Additionally, common metal ions in most paper fillers, inks, pigments, as well as some sugars and amino acids showed minimal interference with the pH response of the composite BC membrane, highlighting its potential and broad applicability for visual acidity detection in paper-based cultural relics.

Development of an osmosis-assisted hollow microneedle array integrated with dual-functional electrochemical sensor for urea and pH monitoring in interstitial fluid

In healthcare, accurate detection of biomarkers is paramount for disease diagnosis, prevention, and personal health surveillance. This study focused on developing and validating a MgCl2 deposited hollow microneedle array integrated with a dual-functional sensor system, which was used for osmosis-assisted boosted interstitial fluid extraction, the simultaneous and continuous monitoring of urea and pH in interstitial fluid. The urea sensor component was fabricated by electro-depositing prussian blue onto a carbon electrode, followed by applying a molecularly imprinted polymer layer, ensuring high specificity and sensitivity. The pH sensor was constructed through electropolymerization of polyaniline, exhibiting a linear response across a wide pH range. When tested in artificial skin matrix, the system demonstrated excellent in vitro electrochemical sensing performance with high linearity and repeatability. At the same time, the practical in vivo sensing performance of the system was verified in Sprague-Dawley (SD) rats. The development of the system underscores its potential as a valuable tool for continuous health monitoring.

Stable Magnetite@La-Fe Oxide Core-Shell Nanostructures Prepared via Lattice Lock for Reusable Extraction of Phosphate Anions.

Stable magnetic core-shell nanostructures are developed by lattice locking lanthanide-iron (La-Fe) oxide shells with magnetite cores to prevent the release of La from the surfaces of the magnetite nanostructures. The resulting core-shell nanostructures demonstrate excellent outstanding regeneration performance and high adsorption capacity for phosphate (115 mg P·g-1). These nanostructures release minimal La from the magnetite core surfaces after adsorbent regeneration, with a La loss of only 20% compared to the control sample, Mag@La(OH)3. La3+ ions were released at concentrations ranging from 1 to 2.3 μg·L-1 at pH levels of 4 to 8, which is within the metal content range found in natural aquatic environments. These results demonstrate the high stability of the nanostructures after regeneration. Furthermore, the adsorbent exhibits high extraction capacity across a wide pH range of 4 to 10 and performs well even in the presence of interfering anions at phosphate-to-anion molar ratios of 1:5, 1:25, and 1:100. Microscopic and spectroscopic analyses reveal that the primary extraction mechanism of phosphate in the La-containing shells is surface precipitation. This approach not only improves the use of magnetic core-shell nanostructures as adsorbents but also demonstrates the creation of a broad range of stable magnetic functional materials for diverse applications.

Novel Insights in the Application of Probiotic Yeast Saccharomyces boulardii in Dairy Products and Health Promotion.

Probiotic organisms are increasingly being incorporated into foods in order to develop products to prevent and reduce many diseases. Saccharomyces boulardii, a probiotic yeast with unique properties, such as viability over a wide pH range, antibiotic resistance, and the ability to reach a steady state, has an advantage over bacterial probiotics. The present review highlights the potential application of S. boulardii in functional fermented dairy products and the genetic engineering of this probiotic microorganism as a therapeutic agent for the treatment of various infectious diseases. It was found that probiotic yeast stimulates the growth of lactic acid bacteria in dairy products, creating favorable conditions and positively affecting the product's sensory characteristics. Moreover, its viability of more than 106 cfu/mL at the end of the yogurt shelf life confirms its probiotic effect. On the other hand, there is a growing interest in the design of probiotic strains to improve their characteristics and fill existing gaps in their spectrum of action such as the inhibition of some bacterial toxins, as well as anti-inflammatory and immunomodulatory effects. The strengthening of immune functions and effective therapies against various diseases by S. boulardii was confirmed. However, considering this yeast species' potential, further research is necessary to accurately determine the functional properties in terms of incorporation into food matrices and from the aspect of health and well-being claims.

Genome Analysis of a Potential Novel Vibrio Species Secreting pH- and Thermo-Stable Alginate Lyase and Its Application in Producing Alginate Oligosaccharides.

Alginate lyase is an attractive biocatalyst that can specifically degrade alginate to produce oligosaccharides, showing great potential for industrial and medicinal applications. Herein, an alginate-degrading strain HB236076 was isolated from Sargassum sp. in Qionghai, Hainan, China. The low 16S rRNA gene sequence identity (<98.4%), ANI value (<71.9%), and dDDH value (<23.9%) clearly indicated that the isolate represented a potential novel species of the genus Vibrio. The genome contained two chromosomes with lengths of 3,007,948 bp and 874,895 bp, respectively, totaling 3,882,843 bp with a G+C content of 46.5%. Among 3482 genes, 3332 protein-coding genes, 116 tRNA, and 34 rRNA sequences were predicted. Analysis of the amino acid sequences showed that the strain encoded 73 carbohydrate-active enzymes (CAZymes), predicting seven PL7 (Alg1-7) and two PL17 family (Alg8, 9) alginate lyases. The extracellular alginate lyase from strain HB236076 showed the maximum activity at 50 °C and pH 7.0, with over 90% activity measured in the range of 30-60 °C and pH 6.0-10.0, exhibiting a wide range of temperature and pH activities. The enzyme also remained at more than 90% of the original activity at a wide pH range (3.0-9.0) and temperature below 50 °C for more than 2 h, demonstrating significant thermal and pH stabilities. Fe2+ had a good promoting effect on the alginate lyase activity at 10 mM, increasing by 3.5 times. Thin layer chromatography (TLC) and electrospray ionization mass spectrometry (ESI-MS) analyses suggested that alginate lyase in fermentation broth could catalyze sodium alginate to produce disaccharides and trisaccharides, which showed antimicrobial activity against Shigella dysenteriae, Aeromonas hydrophila, Staphylococcus aureus, Streptococcus agalactiae, and Escherichia coli. This research provided extended insights into the production mechanism of alginate lyase from Vibrio sp. HB236076, which was beneficial for further application in the preparation of pH-stable and thermo-stable alginate lyase and alginate oligosaccharides.

Iron nanoparticles enhance the efficiency of single-atom Fenton-like catalyst by boosting Fe-NX activity

Single-atom catalysts (SACs) have been widely employed for the removal of organic contaminants via advanced oxidation processes (AOPs). The underlying principle involves central metal atoms that interact synergistically with surrounding atoms in specific ensembles to adsorb reactants and facilitate catalytic reactions. However, comprehensive studies exploring the ensemble effect of SACs in combination with metal nanoparticles relatively rare. In this study, we have synthesized a highly active iron single-atom catalyst (Fe@BC), which features both Fe-Nx coordination sites and iron nanoparticles. Fe@BC exhibits remarkable adsorption and degradation capabilities for bisphenol A across a wide pH range from 3.0 to 11.0. Scavenging experiments coupled with electron paramagnetic resonance analysis have revealed that •OH and O2•− are the key reactive oxygen species within the Fe@BC/PAA system, with •OH playing a crucial role in the removal of bisphenol A (BPA). Our comprehensive characterization analysis has validated the simultaneous presence of Fe nanoparticles and Fe-Nx sites, which are crucial for the catalyst's high activity. Furthermore, our experimental data highlight the importance of the synergistic effect between these two components. Density Functional Theory calculations have provided additional insights, showing that the presence of iron nanoparticles significantly boosts the Fe-Nx sites' activity. This enhancement is achieved by increasing adsorption energy, promoting electron transfer to peracetic acid (PAA), and decreasing the energy barrier for the formation of active species. These findings are vital for the strategic refinement of Fe single-atom catalysts for PAA-based advanced oxidation processes.

Novel copper-drugs bearing dipodal bis-mercaptobenzimidazoles: Synthesis, crystal structures, in vitro biological activities, DNA binding, DFT calculations and molecular docking

Three novel copper(II) complexes, 1–3, bearing dipodal bis-mercaptobenzimidazole derivatives based on ortho-, meta- or para-xylene (L1, L2, and L3) were successfully prepared and characterized by using various spectral techniques, including elemental analysis, FT-IR, 1H NMR, and UV–Vis spectroscopy, LC-MS spectrometry and TGA. The analysis revealed that the ligand/metal molar ratio in all copper(II) complexes is 1:1 and the ligand coordinates as a neutral N-donor onto metal center. Additionally, the crystal structures of L1, L2, L3, and copper(II) complex 2 were determined using single crystal X-ray diffraction (SC-XRD) analysis. Copper(II) complexes 1–3 displayed significant stability at pH range of 4–10. The antibacterial effect of ligands and complexes was tested against both gram-negative (Escherichia coli, E. coli ATCC 25922 PTCC 1399) and gram-positive (Staphylococcus aureus, S. aureus ATCC 6538 PTCC 1112) bacterial strains. It should be noted that the complexes showed enhanced antibacterial activity (up to 99 %) when compared to their free ligands. The in vitro studies of all synthesized compounds consisted of testing them against the human colorectal carcinoma cancer cell line (HCT-116) using the MTT assay. The findings revealed that the copper(II) complexes exhibited lower CC50 values (CC50 ranging from 0.045 mM to 0.135 mM) compared to their corresponding ligands (CC50 ranging from 0.150 mM to 0.240 mM) and carboplatin (CC50 = 0.165 mM), indicating higher anticancer activity of the complexes. Additionally, DAPI staining and fluorescence spectroscopy (at three different temperatures) were performed to further examine the impact of complexes 1–3 on inducing apoptosis and to explore their interaction with DNA, respectively. The results revealed a dynamic quenching mechanism, with hydrophobic forces playing a dominant role in the binding process. The viscosity measurements indicated that all complexes could interact in a groove binding manner with DNA. Density functional theory (DFT) calculations were employed to support the structural and vibrational studies and to predict the chemical reactivity. Docking simulations were conducted to evaluate their behavior of the synthesized compounds towards DNA (PDB: 1BNA). These results suggested that various elements, including NH groups, imidazole rings, thioetheric sulfur atom and sulfate moieties of ligands and complexes, are involved in groove binding with DNA.

Double cross-linked chitosan sponge encapsulated with ZrO2/soy protein isolate amyloid fibrils nanoparticles for the fluoride ion removal from water

Fluoride ion pollution in water has become a serious threat to the water environment and human health. Adsorption is a promising means of fluoride removal, but it also faces challenges such as the difficult separation and recovery of powdered particles, the leaching of modified coatings from adsorbents, and the structural disintegration of macroscopic adsorbents. For addressing the above challenges, glutaraldehyde/polyvinyl alcohol co-crosslinked ZrSAF/chitosan spongy composites (ZrS/GPCS) were prepared by utilizing encapsulation strategies and cross-linking. ZrS/GPCS-1, ZrS/GPCS-3 and ZrS/GPCS-4 were prepared due to the different amounts of cross-linking agents. The results showed that their fluoride ion adsorption capacities were 42.02, 44.44 and 39.84 mg/g, respectively. The removal of fluoride ions by ZrS/GPCS was maintained at >80 % in the pH range of 4–10. The addition of glutaraldehyde and polyvinyl alcohol affected the contact efficiency of fluoride ions with chitosan and ZrSAF, influencing the adsorption rate and adsorption effect. Glutaraldehyde, polyvinyl alcohol and ZrSAF improved the thermal stability, mechanical properties and structural integrity of chitosan matrix. Both the chitosan matrix and the internal ZrSAF played an important role in fluoride removal, and the removal mechanisms included electrostatic interaction, hydrogen bonding, and complexation.

Cyano-functionalized porous hyper-crosslinked cationic polymers for efficient preconcentration and detection of phenolic endocrine disruptors in fresh water and fish

Sensitively analyzing phenolic endocrine-disrupting chemicals (EDCs) in environmental substrates and aquatic organisms provides a significant challenge. Here, we developed a novel porous hyper-crosslinked ionic polymer bearing cyano groups (CN-HIP) as adsorbent for the highly efficient solid phase extraction (SPE) of phenolic EDCs in water and fish. The CN-HIP gave an excellent adsorption capability for targeted EDCs over a wide pH range, and the adsorption capacity was superior to that of several common commercial SPE adsorbents. The coexistence of electrostatic forces, hydrogen bond, and π-π interactions was confirmed as the main adsorption mechanism. A sensitive quantitative method was established by coupling CN-HIP based SPE method with high-performance liquid chromatography for the simultaneously determining trace bisphenol A, bisphenol F, bisphenol B and 4-tert-butylphenol in fresh water and fish. The method afforded lower detection limits (S/N = 3) (at 0.03–0.10 ng mL−1 for water and 0.8–4.0 ng g−1 for fish), high accuracy (the recovery of spiked sample at 88.0%–112 %) and high precision (the relative standard deviation < 8.5 %). This work provides a feasible method for detecting phenolic EDCs, and also opens a new perspective in developing functionalized cationic adsorbent.

New insights into the singlet oxygen-independent formation of TEMPO signals in electron paramagnetic resonance analysis

Electron paramagnetic resonance (EPR) is currently the most commonly used technique for measurement of singlet oxygen (1O2) in advanced oxidation processes. However, the characteristic EPR signal associated with 1O2 (2,2,6,6-tetramethylpiperidine-N-oxide radical, TEMPO) can be generated via alternative pathways not involving 1O2, leading to misinterpreted results. In this study, in-situ EPR analysis was used to re-examine the interaction between peroxymonosulfate (PMS), a common oxidant, and 2,2,6,6-tetramethyl-4-piperidinol (TEMP), the spin-trapping agent of 1O2. It was found that TEMPO could be generated in TEMP/PMS system over a broad pH range (3.0–11.0). The pathway for TEMPO formation was the direct oxidation of TEMP by PMS, and 1O2 was not involved. Furthermore, the intensity of TEMPO (ITEMPO) followed a reverse parabolic pattern as the [TEMP]/[PMS] ratios changed across all pH values. Kinetic analysis unveiled three distinct patterns (continuous linear increase; linear increase followed by a lower rate of increase; increase followed by reaching a plateau) in ITEMPO. Finally, an electron transfer mechanism was proposed for the conversion of TEMP to TEMPO by PMS. The results from this study are expected to advance the understanding of 1O2-independent formation of TEMPO in TEMP/PMS and to mitigate the interference during the detection of 1O2 by EPR.

Development of a Rapid Fluorescence Probe for the Determination of Aqueous Hypochlorite

Chlorine interacts with aqueous environments, including the mucosa and alveolar fluid in the lungs, causing its the immediate transformation to hypochlorous acid (HClO) and hydrochloric acid (HCl) which induces cellular damage and may produce systemic toxicity. There are multiple techniques to monitor hypochlorite (HClO/ClO−) from various matrices, however, they each have significant disadvantages, including limited sensitivity, complexity, and slow response. In this study, we developed a water-soluble fluorescein-based probe, called fluorescein thioacid (FSH), for the rapid and sensitive detection of HClO/ClO− in aqueous solutions via oxidation of FSH to produce fluorescein. FSH was synthesized via a simple, one-step procedure and exhibited excellent selectivity for ClO−, maintaining 82% signal stability for 24 h. FSH performed well over a wide pH range (4–10; optimum pH of 4), produced a linear range from 1 to 100 µM, and had a detection limit of 100 nM. The probe was able to accurately quantify HClO/ClO− concentrations in tap water (13.8 μM) and swimming pool water (56.9 μM) samples. Overall, FSH is simple to synthesize, highly selective, highly sensitive, has excellent water solubility, and produces a fast response for monitoring of aqueous ClO− levels.

Assessment of microbial quality of some industrially packed food seasoning obtained from different retail outlets in Ota, Ogun State, Nigeria

Qualities of curry, thyme and pepper commonly marketed in Nigeria were investigated. The total bacterial and fungal counts, types of microorganisms present and the physico-chemical qualities were also determined. These spices had a pH range from 5.92 to 6.44, with a moisture content of 6.08% to 36.32%. The bacterial load was within the range of 13.0 × 103 to 43.8 × 103 cfu/g with a lower fungal count of 6.5 × 103 to 35.2×103 cfu/g. Five bacterial and six fungal species namely Aeromonas, Staphylococcus, Pseudomonas, Streptococcus and Bacillus;as well as Mucor, Aspergillus flavus, Penicillum, Candida, Aspergillus and Rhodotorula, respectively, were isolated. The implication of these findings on the health of the populace was discussed from a microbiological viewpoint. The presence of these microbes in the spices may pose a serious threat which is of significance in public health.

Magnesium-modified starch cryogels for the recovery of nitrogen and phosphorus from wastewater and its potential as a fertilizer substitute: A novel nutrient recovery approach

Nitrogen (N) and phosphorus (P) are primary pollutants contributing to water quality degradation and eutrophication but are also indispensable resources for agricultural production. In this study, we synthesized porous MgO/Mg(OH)2-modified starch gels (SC-M/SC-OM) to facilitate the simultaneous removal of N and P from wastewater and address the challenges associated with separating and recycling powdered materials. By immobilizing magnesium powder within the matrix of starch gel, with the addition of 1.7 % w/w of MgO and 2.4 % w/w of Mg(OH)₂, the adsorbent can be efficiently recovered from the liquid phase, minimizing material loss. Due to their inherent pH-regulating capabilities, the modified starch gels exhibited excellent removal performance over a wide pH range. At the appropriate adsorbent dose, the maximum recovery of SC-M was 70.072 mg/g P and 25.517 mg/g N, whereas SC-OM was marginally inferior to SC-M. The pseudo-first kinetic model more accurately represented the adsorption of the two materials, showing that N and P concentrations mainly affected the adsorption efficiency, which benefits nutrient recovery at higher concentrations. Starch gels function as carriers for powdered magnesium and contribute to the synergistic removal of N and P, particularly enhancing P removal. SC-OM primarily facilitates the recovery of N and P by forming struvite. At the same time, the adsorption during the hydration process of MgO also plays a crucial role in the recovery with SC-M. Finally, the pot experiment confirmed the feasibility of using the recovered SC as a sustained release fertilizer. This study reveals the significant potential of SC-M/SC-OM for environmentally friendly nutrient removal and recovery, providing a promising approach for wastewater treatment and nutrient recycling.

Vertically-stacked W/W2C heterojunctions with high electrocatalytic capability for the hydrogen evolution reaction in a wide pH range

The hydrogen evolution reaction (HER) in water splitting is among the foremost methods to produce clean and green hydrogen from renewable sources. The practical use of the HER technology is however hindered by the high price and/or the relatively low efficiency of the currently used catalysts. Herein, we report a heterostructured W/W2C electrocatalyst featuring vertically stacked interfaces and embedded in N-doped porous graphitic carbon (denoted as W/W2C@N-PGC) as a high-performance electrocatalyst for the HER in a wide pH range. The catalyst synthesis, accomplished through a straightforward one-pot method, is both facile and highly efficient, involving freeze-drying a suspension of the starting materials followed by pyrolyzing the obtained dry gel. Density functional theory calculations revealed the crucial role of the W/W2C heterojunction in promoting the two key steps of the HER, viz. HOH bond scission and H2 emission. Electrochemical data confirmed the excellent electrocatalytic capability of W/W2C@N-PGC toward the HER process in a wide pH range including alkaline, acidic, and neutral electrolytes. In 1.0 M KOH, we measured a low overpotential of 102 mV to drive a current density of 10 mA cm−2; a long-term stability (up to 24 h) was also realized. The data presented in this work highlight the importance of electrocatalysts with heterojunctions for the HER and the methodology presented in this work may be extended to other contemporary energy-related technologies such as CO2 reduction, oxygen evolution, and oxygen reduction reactions.

Photocatalytic degradation of the remazol red ultra RGB dye using SrFe12O19-Fe3O4 magnetic oxides dispersed in silica: Effect of reduction temperature

Dyes are the most frequently discarded industrial wastes in aquatic ecosystems, among which Remazol Red ultra RGB stands out. In this context, magnetic iron-based catalyst dispersed in silica were prepared by Pechini route as an alternative for the photodegradation of Remazol Red Ultra RGB. The XRD and Mössbauer spectroscopy results indicated the formation of a magnetic material that, after reduction treatment with H2, forms a magnetite phase combined with Sr hexaferrite dispersed in amorphous silica. The TPR-H2 profiles indicated the reduction of Fe3+ to Fe2+ within the considered temperature range, the amount of Fe2+ increased with rising temperature. The SEM images showed sponge-like morphology for the samples. The EDS spectra and mapping confirmed a high uniformity in the distribution of active iron species in the silica. The magnetic measurements showed a lower magnetic signal for the sample reduced at 600 °C, due to the lower magnetic moment of Fe2+ formed after the reduction. The diffuse reflectance spectra showed a main absorption region between 500 and 200 nm and the estimated band-gap values were of 1.4 and 1.9 eV for the reduced sample and the fresh oxide, respectively. The surface charge was obtained via zeta potential, demonstrating good stability under pH changes and reaching a negative potential in the pH range from 2 to 6. The photocatalytic tests showed that the samples with higher content of Fe2+ demonstrated a greater photocatalytic degradation of the Remazol Red Ultra RGB dye, reaching 100 % degradation in 1 h for the solid reduced at 600 °C. A plausible mechanism for the photodegradation of Remazol Red Ultra RGB was proposed, considering the different elementary steps involving the participation of iron sites and the formation of oxidant radicals.

Introducing macrocyclic glycopeptide columns as unique achiral stationary phases: Insights from hydrophobic subtraction model and in-silico modeling

BackgroundThe need for stationary phases with unique selectivity in reversed-phase liquid chromatography has been of utmost importance to chromatographers for advancing the analysis of complex samples. Macrocyclic glycopeptide based stationary phases have been widely used for chiral separations with different chromatographic modes such as normal phase, reversed phase, and supercritical fluid chromatography. Given the multimodal retention mechanisms namely π-π complex interaction, hydrogen bonding, dipole-dipole interaction, and strong Coulombic interactions by which analytes are separated using the macrocyclic glycopeptides, these stationary phases are expected to provide novel selectivity when used under the reversed phase for achiral separations. ResultsHerein, for the first time we have conducted a systematic study using the improved hydrophobic subtraction model (HSM) which incoporates dipole-dipole interactions to demonstrate the novel selectivity offered by four different macrocyclic glycopeptide based stationary phases, namely NicoShell, TeicoShell, TagShell, and VancoShell. A comparison of the HSM parameters for these columns has been made with 551 commercially available reversed phase stationary phases and the differences in the values point to the importance of adding these columns to the already existing arsenal. These stationary phases offer separations over a wide range of pH and show variability in selectivity depending on the pH of the mobile phase which make them versatile for method development in the reversed phase mode. Additionally, we have provided an actual example of a separation from an Amgen discovery project using the VancoShell column aided by computer-assisted modelling. SignificanceThis is the first report characterizing macrocyclic glycopeptides for achiral RPLC applications. The selectivity of these stationary phases were found to be unique when compared to other commercially available stationary phases thereby acting as their own class of columns. The unusual selectivity of the columns enabled separation of complex pharmaceutical samples.

Mechanistic insights into selenite and selenate immobilization using brucite-rich magnesium precipitate derived from seawater electrochlorination facility

This study explored the application of magnesium precipitate (MP) obtained from seawater electrochlorination storage tanks as an innovative and sustainable adsorbent for Se(IV) and Se(VI) in water. Initially, the collected pristine MP mainly consisted of the low crystalline Mg(OH)2 (brucite) phase. Subsequently, the MP underwent calcination (CMP), and analyses via scanning electron microscopy (SEM) and X-ray diffraction (XRD) confirmed an improved crystallinity, displaying a typical hexagonal plate structure in the aqueous phase. Notably, the CMP exhibited a significant adsorption capacity (qm: 85.0 mg/g) for Se(IV), while the adsorption capacity for Se(VI) was lower, determined as 3.0 mg/g using the Langmuir adsorption model. Se(IV) adsorption remained relatively consistent across a wide pH range and ionic strength in the presence of competing anions. In contrast, Se(VI) adsorption varied under the same conditions. This differing adsorption behavior of Se(IV) and Se(VI) on CMP could be ascribed to different mechanisms: inner-sphere predominant surface complexation for Se(IV) and outer-sphere complexation for Se(VI). These mechanisms were confirmed via X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), XRD, and SEM analyses, and surface complexation modeling (PHREEQC–PEST) of the batch experimental results. In conclusion, these findings underscored the potential utility of MP as an effective adsorbent for selenium, positioning it as an environmentally sustainable and significant novel material. Furthermore, the study offered mechanistic insights into the interaction between CMP, Se (IV), and Se(VI) in the aqueous phase.

The Effect of Different Storage Temperatures over Time on the pH of Mammary Gland Secretions in Periparturient Mares.

The objectives of this study were (i) to determine pH and electrolyte concentrations in MGS collected prepartum and at parturition, (ii) to characterize mare milk pH during the first week postpartum, and (iii) to evaluate pre-foaling MGS pH at three storage temperatures. This study outlined two hypotheses: (i) all mares exhibit acidic pH, increased calcium, magnesium, and potassium, and reduced sodium concentrations regardless of prepartum pH and electrolytes; (ii) pre-foaling MGS pH varies with storage temperature and time in an initial value-dependent manner. Twenty-three multiparous mares were monitored daily from 320 days of gestation until parturition. Pre-foaling MGS was collected, and pH was immediately measured using a hand-held pH meter. Aliquots were preserved for further electrolyte analysis. Postpartum, samples from day -7 to 0 (day of foaling) were thawed, and electrolyte concentrations (calcium, magnesium, sodium, potassium) were determined. For the three storage temperatures, pH was measured at 0, 15, 30, 45, and 60 min after storage, and hourly for 10 h post-collection. A range of pH 8 to 6.5 was included to avoid bias towards a specific pH value. The chosen pH groups were 8 (range 7.8-8.2), 7.5 (range 7.3-7.7), 7 (6.7-7.2), and 6.5 (6.2-6.6). Overall, storage temperature affects pH (p < 0.05). In conclusion, this study demonstrated that the majority of the mares had sodium-potassium inversion and acidic pH at foaling. Milk pH is neutral up to four days after foaling, becoming slightly alkaline afterwards, with undetermined clinical significance. The pH of MGS showed minimal variation across storage temperatures, except for pH ~7.5, which increased to ~8 post-storage. This study is the first to address these physiological and practical questions about MGS pH in periparturient mares.

ATM kinase phosphorylates Ser15 of p53 in a pH-dependent manner

The phosphorylation of Ser15 in the transactivation domain (TAD) of the tumor suppressor protein 53 (p53) by ataxia-telangiectasia mutated (ATM) kinase is a crucial step in the tumor suppressor function of p53. An understanding of the factors that affect the rate of Ser15 phosphorylation may provide new strategies for the manipulation of the ATM-p53 pathway in cancer therapy. In this study, the effect of electrostatic interactions between ATM and p53 was investigated by measuring the phosphorylation of Ser15 at varying pH ranges from 5 to 9. To achieve this, two different kinase assay methods were utilized: the ELISA technique, which directly quantifies the phosphorylated Ser15, and the Universal Kinase Assay, which assesses the formation of ADP. The results revealed that Ser15 phosphorylation was pH-dependent, with higher phosphorylation rates observed in the alkaline range. To ascertain whether the lower phosphorylation rates observed at acidic pH were due to protein denaturation, a pH-dependent solubility profile was generated using the CamSol server. The obtained results demonstrated comparable solubility rates within the pH range of the kinase assays performed. Furthermore, the significance of negatively charged residues in TAD1-39 was evaluated by substituting Asp and Glu residues with hydrophobic and uncharged hydrophilic residues in TAD1-39 using ChimeraX and subsequently comparing their interactions with the ATM using the protein-protein docking server HADDOCK2.4. The results of the docking simulations indicated that the alteration of negatively charged residues with uncharged ones resulted in a reduction in the efficiency of the interaction between the ATM and TAD1-39. In conclusion, it can be stated that electrostatic interactions between the ATM and TAD are important for optimal Ser15 phosphorylation.

Isolation and Characterization of Novel Escherichia coli O157:H7 Phage SPEC13 as a Therapeutic Agent for E. coli Infections In Vitro and In Vivo.

Escherichia coli O157:H7 is a recognized food-borne pathogen causing severe food poisoning at low doses. Bacteriophages (phages) are FDA-approved for use in food and are suggested as natural preservatives against specific pathogens. A novel phage must be identified and studied to develop a new natural preservative or antimicrobial agent against E. coli O157:H7. The phage SPEC13 displayed broad host range and was classified within the Ackermannviridae family based on its observed characteristics by a TEM and genome analysis. In 10 min, this phage achieves a remarkable 93% adsorption rate with the host. Its latency period then lasts about 20 min, after which it bursts, releasing an average of 139 ± 3 PFU/cell. It exhibited robustness within a pH range of 4 to 12, indicating resilience under diverse environmental circumstances. Furthermore, SPEC13 demonstrated stability at an ambient temperature up to 60 °C. A whole genome and phylogenetics analysis revealed that SPEC13 is a novel identified phage, lacking a lysogenic life cycle, antibiotic resistance genes, or genes associated with virulence, thereby presenting a promising biological agent for therapeutic application. Animal studies showed that SPEC13 effectively controlled the growth of harmful bacteria, resulting in a significant improvement in colon health, marked by reduced swelling (edema) and tissue damage (mucosal injury). The introduction of SPEC13 resulted in a substantial decrease in quantities of E. coli O157:H7, reducing the bacterial load to approximately 5 log CFU/g of feces. In conclusion, SPEC13 emerges as a promising inclusion in the array of phage therapy, offering a targeted and efficient approach for addressing bacterial infections.